Note: Descriptions are shown in the official language in which they were submitted.
~2~
A. Field of the ~nvention
_
This invention relates to a loom weaving syætem in which the weft
is inserted through the shed of the loom by means of a pulse-like jet of
air or other pressuri~ed gaseous medium (hereinafter referred to
5 generally as an air weft insertion system) and is concerned more parti-
cularly with an efficiently operating air waft insertion system capable of
~ubEtantially increasing the in ertion velocity of the air jet through the
loom shed compared to existing systems wi~h a corresponding reduction
i~ actual weft insertion times to adapt the system for high speed weaving.
B. B c~nd of the Invention and Pr or Practice .
In all weaving, arl initially flat array of longitudinally extending
warp threads is divided into at least two interspersed groups which are
~eparated in opposite directions from the starting plane to define between
the separated warp groups an elongated diamond shaped 6pace, known as
15 a "shed", through which the weft or filling is in~erted, the direction of
separation of the warp groups being reversed in a gi~en order after each
~;uch wet by means of a harnef~R motion with the result that the warp
threads are entwi;led in sinuo-.ls fashion around succe6sive filling threads
to form the woven fabric. Traditionally, the weft is carried in coiled
20 ~orm upon a bobbin held within a shuttle, and as the weaving progresses,
the shuttle is propelled alternatively back and forth through the shed on
the upper surface of a beam-like la~ which carries a colnb-like reed pro-
jecting upwardly therefrom and rocks bac1-~ and forth to press or "beat up"
each new weft by means of the reed against the working end or "fell" of
25 the fabric being woven. I~ the traclitional loom, bobbin propulsion was
accomplished by means of so-called picker sticks mounted on the loom
adjacent opposite side edges of the warp for pivotal movement about their
28 lower ends and driven to all:ernately iII-lpaCt tlleir upper ends against the
3~ 65
chuttle. Obviously, this conventional design was aubject to inherent
limitations as to achievable shuttle speed and was, ~noreover, accompa-
nied by substantial disadvantages; namely, deafening operating noise as
well as risk of breakage of picker sticks or other damage to equipment
5 and of danger to operating personnel when, aa occasionally happened,
the shuttle escaped its containment and beca~ne an uncontrolled projectile.
In order to overcome these inherent problems in bobbin type weaving, the
prior art has explored various alternatives, and in the past decade or so,
increasing attention has been directed to the possibility of impelling the
10 weft thread through the shed by means of a jet of fluid. Jets of water
have been found to be a relatively manageable projection medium, but
water is a possible cause of corrosion and limits the choice of yarn
material; thus there are significant advantages in the use of a gaseous
fluid. While gases other than air can in theory serve equally well, cost
15 considerations dictate the choice of air as the only practical gaseous pro-
pelling medium; consequently, this mode oE weaving will hereinafter be
referred to for convenience as "air weft insertion", although the use in-
stead of other gases is, in principle, intended to be included.
In general, air projection techniques that have been used in
20 past air weft insertion systems fall into two basic categories. In one
type, the weft end is initially projected by means of a pressurized air
from a nozz1e situated outside and adjacent one side of the warp shed
; which serves to initially acceler~e the weft end and startj its tra~rel
through the shed, The propulsion forces of existing nozzles is severely
25 limited in terms of the attainable length o~ projection of the weft end and
- hence, in this type, a plurality of "booster" or supplemental jet nozzles
is proYided at spaced intervals through the shed, such nozzles being
2~ inserted wi~ and removed in various ways fronn the shed interior ~ria
365
the clearance bstween the warp yarns. The aggrs8ate of the propulsion
forces of this multi-stage sequence of nozzles can be sufficient to convey
the weft thread across the full width of the loom.
While this approach has proved generally feasible in practice, it
too i8 faced with definite disadvantages, ~i7, the requirement for care-
fully controlled timing of the sequence of nozzle action plu8 excessive
co~sumption o~ compressed air and thus poor economic eficiency.
In order t~ a~roid the ~eed for booster nozzlçs disposed at in-
tervals through the shed, an alternative approach has been developed in
a second type which utilizes a single exterior insertion nozzle in con-
junction with a weft guidarlce "tube" situated within the shed. Since
during weaving, the groups of warp threads must shift up and down
past one another, the presence of any continuou~ body within the shed
turmg shedding is out of the question. Thereore5 an "interrupted"
weft guitance tube is used, taking the forrn~ of a plurality of generally
annular segments, each shaped to sufficieI!Ltly narrow thickness in its
axlal dimension as to pass between adjacent warp hreads arranged in an
axially aliglled positicn so as to constitute together a lengthwise in-
terrupted tubular member extending ~ubstantially the entirety of the ~hed
width. Each annular segrnent has a slot-like exit opening at a point on
its periphery to allow lateral egress of the inserted weft thread when the
guidance tube is withdrawn below the shed. When the weft thread is pro-
jected by the exterior nozzle into one end of this interrupted guidance
- tube, the projection force in~parted to the thread by the no=zle appears to
be substantially enhanced so that the distance the weft thread i~ pro-
pelled by this force can be significantly increased compared to the nozzle
alone.
28 The reasons why the interrupted guidance tube extends the
projection force of ths nozzle are not totally under6tood at present. The
adjacent segments of this tube are separated by clearance spaces which
are sufficient to permit pressurized air delivered into one end of the
tube to disperse to the outside atmosphere while the interior edges of the
5 bore of the segments ~hould present considerable frictional resistance to
mosrement of an air je$ therethrough; from this standpoint the effect of
6uch a tube might be expected to be negative. On the other hand, ambient
air could be entrained from the ambient atmosphere into the interior of
the tube through the same inter-3egment spaces with the possible effect
10 of augmenting the propelling forces. In any event, it is established that
the addition of a weft guidance tube generally as described above sub-
~tantially increases the distance a weft thread can be projected with a
jet of compressed air emitted from a nozzle.
Numerous improvements ha~e been suggested in ~is second type
15 of air weft insertion system which in general have focused UpOTl refine-
ments in various aspects of the system, incl~ding enhancing the effect of
the guidance tube by means, for instance, of arrangernents capable of
temporarily reducing the clearance space l:etween the segments thereof
during the weft insertion phase of the cycle or by developing superior
20 aerodynamic characteri~tics for such elements> optimizing the delivery
- of a measured weft length to the insertion nozzle through a variety of
weft measuring and storage devices intended to minimi~e the resistance
of the weft length to propulsion and hence utilize to maxinlum advantage
the thrust capability of a given no~zle, and the lil~e. With rare ex-
25 ceptions, the prior art efforts ~ this type of sy~tem have given little
attention to the fundamental behavior of the air delivery stream it~elf.
It is known according to aerodynamic theory tbat the thrusting
28 force ( dF applied by a moving gaseous stream to an element disposed
-4-
therein with a given unit length (dx) and a circurnference ~D) is deter-
m,ined by the equationo
dF = Cf . 1/2~ (Vg ~Ve) .~D . dx
whe~e p ;~ the density of the gaseous medium, Cf i9 a factox Yarying with
5 the condition of the elernent and is roughly constant for a given thread,
V is the velocity of the medium, Ye iB the velocity of the elernent and D
g
is the diameter of the element. ~ a given syste m the dian~eter and
factor Cf ~irill ordinarily be fixed; hence, thrusting force is essentially a
function of the des~sity of the mediurn and the square of the difference in
10 velocity between the moving gaseous medium and the element. ln inserting
weft in the shed of a loom, the weft will norrnally be stationary prior to
the insertion so that Ve become6 zero and the ~tarting thrusting force,
therefore, is essentially proportional to p~Jg2
The practicai application of this result is sornewhat complicated
lS by the generally opposing behavior of ~elocity and density in the system
in question. At velocities below sonic speed (sonic speed being referred
to as a ~ach No. of 1 or "Mach 1"), ~elocitq ~aries with the square root
of l;he head pressure so that in order, or example, to double the velo-
city the pressure must be quadrupled. At a given head pressure, as
20 the air accelerates along the noz~le9 the pressure drops and is
accompanied by a decrease in density according to the relationship re-
quired for adiabatic processes. When Vg reaches sonic velocity in the
throat ~f the nozzle, the rate of change in p has become exactly equal to
the rate of change of Vg and pvg thus has its maxLmum value at the
25 throat for a given supply pressure. At all velocities above sonic ~relocity,
p decreases more rapidly than Vg increase6. From Mach 1 to M~ch
1.414, the relative rates of change are ~uch that pvg2 continues to in-
Z8 crea;e, while above Mach 1.414 p decreases at ;~ficien;ly hi~her rate;
than Vg increases that pvg2 becomes isimaller so that for exa~nple pvg2
is approximately- the same at Mach 2 as at Mach 1.
As the head pressure is made greater, Vg increases, as
mentioned, until sonic velocity IS achieved, but further increases in head
presisure produce increases only in the ultimate le~el o p in the throat
and not in ~g. That i8, the highest throat velocity possible is Mach 1
irrespective of increases in pressure which only serve to make the gas
more denise. Acceleration of the gas to ~uperRonic speed i6 possible only
by increasing the volume of the space downs.ream of the throat to allow
the densified gas to expand and decrease p, and hence make it possible
for Vg to increa~e. If the nozzle throat opens directly into the ambient
atmosphere, the gas can expand randomly for a short di~tance while iE
the nozzle has a convergently contoured section below the throat ~as thus
forms a so-called super-sonic nozzle) the gas can expand in a controlled
1 5 fashion.
For gas velocities above Mach 1 downstrean~ of the throat, the
,
pressure increase required for a gi~ren change in Mach No. is a geo-
metrical rather than a lineal funchon. For example, the theoretical
ratio of head pressure to ambient pressure for Mach 1 is approximately
`- 20 1.9, for Mach 1.414 approximately 3.25/1, for Mach 2 about 7.9/1 and
in practice should be somewhat higher.
Clearly from these technical considerations, increasing Vg by
increasing head pressure definitely appears to be an unpromising way in
terms of cost effectiveness of increasing the thrusting force dF in the
2S above equation since at below sonic speeds a given theoretical increase
in Vg requires the head pressure to be increased by the square of the
~ifference and this disproportionality between velocity change and h~d
28 pressu,e change comes even worse at above sonic velocities.
-6-
Eurther, the gas velocity in the throat can in any case never exceed sonic
~peed and-the essential thrusting orce pvg itself is subject to limiting
value at the low level of Mach 1.414 and can the~eafter only decline.
To the apparent technical cost disad~rantage of high nozzle
5 pressures must be added the practical necessity for pressurized air used
for weft insertion to be free of contaminants such as oil and dust particles.
The production of such clean air requires special centrifugal compressols
and/or special filtration devices which substantially inerease the mach-
inery investment for a given installation.
10 ~ For these and other rea~ons, prior art workers in weft insertion
ystems have without known exception accepted the priDciple of a low
pre6sure air supply and low air jet velocity as unavoidable conditions and
ha~e striven to use these given conditions with maxiIrlum effectiveness,
placing their concentration on other techniques, as stated.
In any weaving operation, each we~ing cycle di~ides into two
main phases, the weft insertion phase, which OCCUl s generally at the
rearward end of the lay rocking motion, and the beat up phase, which
occurs when the lay is rocked forwardly to the other limit of its arcuate
path to pack, or beat up, the newly inserted weft end (or pickj against the
20 fell of the already woven fabric, with the fabric beiTlg stepwise advanced
as needed to maintain the fell at a fixed location. Various attempts have
been made to shorten the beat up phase, so as to thereby increase over-
all weav~ng speed, by employing, for example, special mechanical
drives designed to accelerate lay movement during beat up, and speciaily
~5 constructed lays with shortened pivot supports and reduced mass to
shorten the arc ol lay traveï and lessen inertial orces in~rolved in driving
the lay, all of which can be advantageous. There are, howe~er, inherent
28 limitations on how far beat up tirrle can be reduced in this way;
-7
consequently, the achievement of truly high speed loom operation, i. e.
in the order of 1, 000 weft inæertions or picks per minute, i8 ultimately
possible only by taking less time to insert the weft itself. ~;pecifically,
at 1, 000 picks per minul:e, only a total o 60 milliseconds i8 available for
5 an entire weft insertion or picking cycle, i. e. the lapsed time one beat
up to the next. Prior art air weft in6ertion systems normally require at
least 50-60 ~nillisec onds for weft insertion alone, apart from the beat up
phase, and have, therefore, been inherently limited in operating speeds.
There are presently in use or available for use in the teæiile
10 industry several millions of existing shuttle-type looms which were de-
~igned for operation at speeds of up to about 150-200 picks per minute
znd cannot be adapted for high ~peed op ration without a virtual complete
rebuilding. However, with a fairly modest amount of n~echanical ~nodifi-
cation, such looms can be dri~en at speed~ of about 400 cycles per minute.
15 At this speed, the period requiled for one complete cycle i9 150 ms, and
in theory, weft insertion times in the order of 5D-60 ms as eharacter~
istic o~ the prior art ~night be tolerable in a cy~le of this duration.
HoweYer, at insertion times of this order, loo~n operation would become
somewhat critical due to the large proportion of total cycle time con-
20 sumed by the insertion time, and might require special "dwell motions"or this purpose. Conjequently, it would be of a definite benefit in the
conversion of existing shuttle looms to air weft insertion for the weft in-
sertion time to be reduced sub6tantially below the prior art level and
thereby impart greater flexibility to and reduce critica]ity in the opera-
Z5 tion of BUCh converted looms.C. Discovery of the Invention
As stated above, if a compressible gas is supplied to a nozzle
2~ converging at some point to an opening or throat of minimum cro~s-
s
ectional area, and the pressure acting on the gaseous }nedium i8 gradually
increased, the velocity of the gas at the throat can at most only equal
conic speed, and any further increase ln the pressure on the gas only in-
creases the denæity of the gas stream without any increase in gas ~relocity
above sonic velocity. At this condition, the nozzle is said to be "choked"
and the minimum ratio of head pressure to ambient pressure at which
this choking condition occurs i9 equal to approximately two.
According to the invention, it has been discovered contrary to
all reasonable ex~?ectations that if in a weft insertion system including an
inter~upted 8~idance tube, a convergent weft insertion noz~;le is supplied
with air at a pressure exceeding the pressure required to choke the nozzle
throat for a controlled sustained time, the nozzle in fact has the capacity
for effective utilization of the pressure energy of the air for transporting
- the weft, per~nitting projection of the weft through the loom ~hed in periods
of time ~ubstantially less than with prior art systems of this type and that
it becomes possibl~ to avoid excessive energy consumption by n~odul~tion
of the pressure output from the no~zle withc>ut significant reduction in
weft transporting perfo mance.
D. Statement of Ob;~s
The ultimate object of the present invention is, therefore, the
- provision of an improved air weft insertion system which iB adapted for
utilization equally in the conversion of existing shuttle looms as in a
specially redesigned new loom and is characterized by improved perform-
ance and reliability with reduced consumption of compressed air energy.
A further object of the invention is tha provision of a weft in-
- sertion air nozzle des;gned with the capacity for maximum transmission
of thrust to the wet.
-~ 28 A still Iurther object o the invention is an actuation control
. . . . ..
. . .
~mit for the improved weft insertion no~zle which can either be electric-
ally or mechanically activated and makes possible accelerated and pre
cisely reproducible response times in the firing of the noz~le.
Another object of the invention is an improved weft metering and
S ~torage unit capable of automatically supplying a l~ngth of weft precisely
matched to the width of the loom to the insertion nozzle without complex
control instrumentation.
Another object of the invention is an improved Tnounting for an
interrupted in-shed weft guidance tube which iB effective to positively with-
10 draw the guidance tube outside of the shed automatically during the beat-
up motion c>f the lay.
A~other object of the invention is a weft lift-out device serving
to positively re~notre the inserted weft from the guidance tube in l~esponse
to the beat up of the lay.
A further object of the invention is the creation of an improved
fabric selvage utilizing a cvmbination of a leno selvage weave with an ad-
jacent pair of twisted binder threads which maintains the integrity of the
sel rage.
A still fur!her object is an impro~ed ~upport for the weft recep-
20 tion tube which automatically adjusts the position of that tube to maintainthe same in registration with the path of the weft throughout the weaving
cycle.
These and other objects and advantages will be explained in
greater detail by the following detailed description when ~ead in con-
Z5 junction with the accompanying drawings in which:E. Brief Descri~tion of Drawi~
These and other objects and ad~antage6 will be more fully ex-
28 plained by the following complete description when read in conjunction
5with the accompanying drawings in which:
Fig. 1 is a highly schematic view in perspective of the es~ential
cornponents of a loom incorporating the present invention;
Fig~. 2A and 2B are enlarged detail views looking at the left end
5 ~f the lay of the loom of Fig. I in rearward weft inserting po~ition and
forward beat up position, respectively, showing the compound motion o
the weft guidance tube;
Fig. 3 is an enlarged detailed ~riew of the upper portion of the lay
in beat up position as in Fig. 2B showing the weft lift-out device in pro-
lO Jected position in solid lines and in retractsd position for weft insertion indotted lines;
Fig. 4 is an enlarged detailed view of one en~bodiment of weft in-
sertion no~zle zccording to the invention taken in cross-~ection through
the nozzle axis;
Fig. 5 is a cro s-sectional view similar to Fig. 4 of a modified
embodiment of weft insertion nozzle;
Fig. 6 is a schematic diagram i11ustrating an electronically
act~ated air control unit for the insertion nozzle of the in~rention;
Fig. 7 is a wave form diagram illustrating the operation of the
20 control unit of Fig. 6;
Fig. 8 is a front perspective view on a mechanically operating air
control unit for the weft inseTtion nozzle with the housing in outline and
the air passage shown schematically as conduits;
Fig. 9 is a sectional view looking down on $he mechanical nozzle
25 control unit of Fig. 8 with the housing shown in cross section and the
rotary spools in pla~;
Fig. 10 is a vertical section somewhat diagrammatic taken
28 through the control unit of Figs 8 and 9~ showing details of the rotary
" , . ,.. , : - ''" ' '''.' '"" , ~ ., ' ,
136~
spools thereof;
Fig. 11 is a side perspecti~e ~iew of a modified mechanically
operating air control unit for the insertion nozzle o~ the invention with the
housing ~hown only in outline and the air conduit~ appearing ~chematically
5 a~ conduits;
Fig. 12 is a vertical section somewhat diagrammatic through the
modified mechanical control unit of Fig. 11 and including the housing;
Fig. 13 iB a wave form diagram illustrating the operation of the
mechanical contrcl unit of Figs. 11 and 12;
Fig~ 14 i~ a side elevational view, partly in cross section, of
,
one embodiment of weft metering and delwering unit utilizing a rotating
drum,
Fig. 15 is an end qlew of the weft metering and delwering unit of
Fig. 14, partly cut away to show the interior of the associated air ring,
:15 Fig. 16 is a 6ide elevational view partially in cross-eection of
a modified weft metering and delivering unit utilizing a stationary winding
: drum;
: Fig. 17 is an end view partially in section of the modified
~: metering and delirering unit of Fig. 16; ~ :
~0 Fig. 18 is a detail view of one form of weft reception tube with
an associated weft engaging clamp;
Fig. 19 is a detail view of a modified weft reception tube in-
corporatir,g photoelectric detection devices for signalling the arri~ral of
`- the weft end;
~5 Fig. 20 is a schematic air circuit diagram for a preferred em-
bodimcnt of the invention;
Fig. 21 is a 6chematic electrical circuit diagram for a preferred
- 28 embodiment of the imrention;
-12-
' ' ' ' ' , ,.",,~
i5
E`ig. 22 is a graph plotting air and weft arrival times against
supply pressure over a range of 40-1~0 p5ig for an 11 rnm2 supersonically
contoured no~zle with and withc~ut extension barrels of lengths equal to 5,
10 and 20 times the diameter of the no~zle outlet;
Fig. 23 is a graph similar to Fig. 22 for three uncontoured
nozzle6 having throat areas of ll, 16, and 32 rnm2, rçspectively, without
e~tension barrels;
Fig. 24 is a 6çhematic view indicating diagrammatically an
arrangement for simulating a prior art air weft insertion ~y~tem;
Fig. 25 i6 a comparative graph similar to Fig. 23 but xepre6ent-
ing the performance of a simulation of a prior art air weft insertion
sy~tem using uncontoured nozzles of ~arying throat areas;
Fig. 26 is a comparati~re graph plotting air and weft arrival times
versus actual nozæle stagnation or head pressure achieved by the prior art
~5 simulation of Fig. 24 with the same nozzles as in the graph of Fig. ~5;
Fig. 27 is a plot similar to Figs. Z2 and 23 of the sy~tem of the
invention comparing the weft arri~ral times over a range of supply pressure-
of 30- IZ0 psig for ~uper~onically contoured nozzles ranging from Mach l. 5
to Mach 2. 079 with and without an extension barrel equal in length to flve
times the nozzle outlet diameter, supplied with air from a large capacity
accumulator, with the Mach 1. S nozzle being also operated with a low
capacity accumulator fc~r comparati~re purposes;
Fig~. Z8A-I represent reproductions of actual 06cillo-
graphically derived pressure traces showing the changes in head pres~ure
2S versus time in air pulses generated by the 11 rnm2 throat area un-
contoured nozzle of Fig. 23 when operated at 10 psi intervaiæ over the
range of supply pressures of 40-lZ0 psig;
28 Figs~ 29A-I are reproductions of pressure trace~ sirnilar to
~ 1 3 -
- - , .
~ 2~3~5
Figs. 28A-I but for a 16 ~n2 throat area uncontoured nozzle and on a
different scale;
Figs. 30A~I are recreations of pressure traces similar to Figs.
28A- I and 29A-I but for the 32 mm2 throat area uncontoured nozzle and
5 on the sarne scale as Fig. 29A;
Figs. 31A-I are comparati~e recreations of pressure traces
si~nilar to Figs. 2~A-I but on a different scale for the prior art simulation
of Figs. 24 and 25 utilizing an 11 mm2 throat area uncontoured nozzle;
Figs. 32A-I are comparative recreations of pressure traces
10 simîlar to Figso 29A-I but on a different Acale for the prior simulation
with a 16 mm2 throat area uncontoured nozzle;
Figs. 33A-I are comparat*e recreations of pressure traces
6imilar to Figs. 30A-I but on a different cale for the prior art simulation
with a 32 mrn2 t~roat area uncs~ntoured nozzle;
lS Fig. 34A is a recreation in terms of head pressure versus time
on a 6till different sc:ale of a pressure trac~e generated by the preferred
.
nozzle~in the system of the invention equipped with an added supply
capacity or accumulator; while F-g. 34B is a recreation of a pressure
trace for the identical system absent any added supply capacity or
~0 accumulator and illustratîng the change in time in peak pulse pressure at
the lower supply capacity cornpared with the pulse of Fig. 34~;
Fig. 35 i8 a reproduction of an ac$ual "strip chart" produced by
a multi-channel o~cillo~cope monitoring one operative cycle of a loom
according to the in~ention following the preferred balanced mode of opera-
tion, and Ahowing wave forms corresponding to nozzle throat pressure,
delivery clamping actuation, weft delivery tension, and weft arriv~l at the
reception tube;
28 Fig. 36 is an enlarged detail plan view o a fragment of l;he
- 14-
. , " . ... .
s
~elvage of the fabric produced by the invention, revealing the combination
of twisted binder strands with a leno selvage wea~re; and
Fig. 37 i~ a detail view of a mechanical arrangement for actuating
the elamp open a-nd close switches permitting precise adjustment of the
5 actuation times thereof.
F. ~=
The loom of the present in~rention i~ basically conventional in
much of it~ con~truction and operation (with one adaptation to better suit
the requirements here), and the loom structure is illustrated schematic-
10 ally in an overall view in Fig. 1 and descsibed generally with alphabeticaldesignation only in enough detail to e~tablish the context of the present
improvements~ As usual, the warp threads on end~ W are carried on a
rotatably supported warp beam (not seen) and pass therefrom through the
eyei~i of parallel arrays of heddIe wires I arranged in two or more separate
15 groups held in adjacent parallel planes by c:orresponding heddle frames~ H.
The heddle frames H are mounted for alternating up and down recipro-
cation whereby the groups of warp threads are separated to form an eIon-
gated diamond-shaped shed S having its front cOrneT defined by the fell E
of the fabric being woven. Forwardly of the heddle frames H, a lay beam
20 B extends withwise acros6 and beneath the lower plane of the warp, the
lay beam B being mounted at its ends on generally upstanding supports or
~words L which are pivoted on a shaft A at their lower ends and are rocked
to and fro by driving rneans, such as a crankshaft, not shown. A reed R
in the form of a sheet-like array of wires on the nat plates with the warp
25 threads pa~sing in the clearance space therebetween projects upwardly
from the rear side of the lay to impress each new weft against the fell as
the lay rocks forwaldly. The wo~en fabric is collected in a conventional
28 way upon a take-up beam, not 6hown.
-15-
. - , - ' ~' ~ ' '' i
The abric has a rough or fringe selvage Q becau~e the weft is
inserted in the warp shed continuou~ly from the same side of the warp
shed rather than alternately from opposite sides a~ in con~rentional
shuttle weaving. This rough selvage may be trimmed by means of trimm-
5 ing shears or knives K in operati~e position at the fell line and actuatedin the usual way.
In accordance with the invention, the lay B of the loom is equIp-
ped with an interrupted segmental weft guidance tube to facilitate in a
manner known in itself the delivery of weft or filling strands F through
10 the shed, the guidance tube obtruding in interdigitating fashion with the
warp ends into the interior of the shed when the lay is in its rear~nost
position and withdrawing from the shed while the lay moves forward.
The lay preferably carries a weft lift-out device generally designated O
to positively displace the inserted weft F from the guidance tube. The
15 weft i9 projected into the interrupted guidance tube by means of a burst
or pulse of air emitted by a weft i~sert;on nozzle N mounted on the lay
adlacent one side of the shed, while the free end of the inserted weft is
received beyond the far side of the shed within a vacuum recept-on tube
carried on ths opposite end of the lay and if desired is engaged by a clamp
~0 5 associated with that tube. Preferably, the tube is displaceably
~upported to follow the path of khe weft during beat up. The reception
tube can include photoelectric detection means (not seen) to deect the
arrival of the weft thereat and initiate a control signal in t~e absence of
the weft. The generation of the pulse or burst of air through the nozzle
25 i8 precisely controlled by means of a nozzle activation control unit which
iB actuated in timed relation to the cyclical operation of the loom. A
proper length of weft is withdrawn from a weft package or other source
Z~ P and made available to the insertion nozzle N by mcans of a strand
~ 1 6 -
Z~6~
metering and deli~erirlg unit M disposed at a ixed position outboard of
the insertion nozzle N, and a clamping -means C iB interposed between the
metering unit M and no~zle N for positively gripping the weft F in timed
relation to the inserting action.
5 G. Detailed Description of In~ention
The various component units of the present system which embody
novel features will now be described individually.
I.
a, ~terrupted Guidance Tube Withdrawa~
In a con~entional loom, the lay consists of a large massive
beam extending entirely across the width of the loom, the upper surface
of the beam lying when in rearward weft insertion position virtually co-
planar with the threads forming the lower side or floor of the shed where-
by the shuttle can slide on the beam when moving through the shed.
~ lS In the loom of the present in~rention, the lay beam's massive-
; ness is e~pendable, a~d only enough of a skeleton beam is retainedj e. g.
in the form of an upwardly opening channel 39 fixed to the ends of lay
swords 1" as required for the mechanical support of various component~
including the segmented or interrupted weft guidance tube T of the in
20 ~ention. As mentioned, thia tube T consists of an axially aligned array
of thin annular segments 41 (better seen in Figs. ~A and 2B) which
preferably have an axia1 thicknes~ not greater than about 1/8" to allow
their introduction upwardly into the interior of the shed S through the
clearance spaces between warp threads W without abrading or other-
25 wise damaging the warp and an annular thickne~s appropriate formechanical strangth, Ray 1/4 - 3/8". Each tube segment 41 has a
radial foot like extension 43 projecting from a lower peripheral point to
i!8 enable the elements to be mounted in spaced axially aligned relation upon
;
-17 ~
6S
a transverse~y extending common base 45 in which the extension
ends 43 are fastened or embedded. Each weft tbread F during
insertion is pro~ected through the interior bore 47 of pre~
determined diameter of the axial array of the annular segments
41 and provision is made for the escape of the weft thread
laterally from the segment array as it is withdrawn from the
shed, by way of a narrow gap ~9 formed in each segment at a
common peripheral point on the rear upper quadrant thereof.
In prior art constructions, the interrupted guidance
tube is fixed relative to the lay. Obviously3 the guidance
tube elements must, in any case, be completely withdrawn from
the interior of the shed S before the reed R reaches beat
up position to permit the weft F to float free within the
shed before being pressed against the fell E of the fabric
by the forward motion of the reed R. In general, prior art
arrangements have usually required some change in the normal
arcuate path of the lay so as to achieve a timely withdrawal of
the guidance tube, for example, by tilting the lay and reed
bodily forwardly toward the fell of the fabric. This results,
however, in the reed having a considerable inclination at
its beat up position whlch means that the force driving the
thread against the fabric fell E is applied at an angle to
the place of the fell, displacing the thread downwardly at
~ the same time as it is pressed forwardly against the fell,
which can lead to distortions in the fabric, whereas in
conventional loom design, the arcuate path of the upper lay
end is more or less symmetrical about a vertical plane so as
to give the best compromise between the preferably horizontal
position of the lay during weft insertion and the preferably
vertical position of the reed at beat up position.
In the present invention, the lay construction is
modified to incorporate a mounting permitting relative
vertical displacement of the
-18-
~J2~365
,.
wet insertion tube. The design of the mounting i~ not critical and can
take ~arious forms. For example, ea~h lay sword can b~ provided with a
vertieally spaced pair of collars 53 in a~ial alignment for sliding recep-
tion of a ~lide rod 55 passing through openings in the botton of channel 39
~Fig. l~ and attached at its upper end to the suppQrting base 45 of insertion
tu~e T. The ends of the base 45 are connected to the upper ends of
generally upstanding driving lir~cs 51 which are pi~,-oted at their lower ends
to the frame of the loom on a picot axi~ 54 di6placed rearwardly from the
pwot axis A of the lay swords L. Con~equently, when the lay pivots, the
upper ends of drive links 51 swing through a more inclined arc indicated
by dashed arrows than the upper ends of the lay swords L creating a ~erti-
cal displacement of the guidance tube base 45, and thus of the guidance tube
: T itself, rela,'ive to the lay channel 39. In this way, during *eat up the
guidance tube T has a con~pound motion, s~vinging arcuately with the lay
while moving vertically by itself, and the point of its full withdrawal from
the ~h~d can, therefore, be varied as desired independently of the position
.. of the lay B by adjusting the position of the lower pi~ot axis 54 o the
dri~e links 51 relatiYe to the pivot axis A of the lay swords L.
Early withdrawal of guidance tube T during beat up is
~; 20 advantageous in giving greater opportunity for the warp threads to recover
from any distortion in their normal position as a con.sequence of the
removal of the guidance tube segments 41 from theTebetween. It has been
found that if the tube i6 fixed Telative to the lay and its withdrawal is thus
delayed, the warp threads (which must shift lat.erally ~omewhat to allow ~ :
pa~sage of the guidance tube segments) may be held in such displaced
position at the time the weft is pressed against the fabric fell and become
, ,
"locked" in this aberrant position when the shed collapse~ during re~7ersal
28 of the warp thread groups of the shed. This results in ob~ervable de~ects
- 19^-
m the uni~orm ~pacing of the warp thread~ within the resultant fabric,
producing what i6 knOWIl a~ a "reedy" fabric, because ~uch defects are
normally characteri~tic of excessively thick reed element60
l~n celecting the position of the exit 61Dt csr gap *9 ~igs. 2A
and 2B) in the guidance tube ~egments 41 along the upper peripheral
portion thereof, consideration should preferably be gi~ren to the compound
motion of guidance tube T"ncluding both the vertical component as well
a~ the usual arcuate component. Thus, the less the vertical displacement
of the guidance tube, the clo~er the position of exit slot 49 to the lower -
end of the upper ~egment quadrant adjacent reed ~ and vice ~ersa.
The guidance tube segments 41 themselve3 can be molded of
a~y 6$rong durable pla~tic material, &uçh a~ that sold under the name
I~elr~, preferably filled or remforced with chopped glas~ fibers for in-
creased 6trength. Segments confitructed in thi~ manner have the 61ight
disadvantage of nonconductivity and ca~ be ~u~ceptible to the build up of
fitatic electrical charges drring weaving. This can be avoided by apply-
ing a metallic coating, ~or ~xample, by vacuum deposition, to the ~egment~
and grounding them electrically to the frame of the loom. Alternatively,
the ~egments can be formed of cast metal. Irl a6sembling the guidar~ce
tubes of the invention, a plurality of such 6egments of &ufficient number
(dependent upon the width of the loom and the desired separation) are
arral~ged in axially aligned position on a jig, giving what has been found
a reasonably accurate alignment with a de~riation of ~ 1 - 2/1000".
Deviation~ of this magnitude can be tolerated without substantial
deleterious effect; however, ~ignificantly better performance can be
achieved when the interior Wall8 of the arrayed ~eg~nents 41 are ~ub-
jected to a honing operation. For this purpose, an elongated rod having
28 a slightly tapered a~ially ~lc>tted cutting head with a maximum diametcr
-20-
8~5
slightly exceeding 1;he starting undersize bore diameter of the ~egments as
molded is passed through the ~egment array while being rotated at a
moderate 6peed of a few hundred rpm, by means for instance of a hand
drill, the head of the rod being coated with any commercial honing com-
pound consisting of a ~ine abrasion suspended in a lubricating carrier.
Honing produce6 highly uniform 3.1ignment of the bore apertures of the
segnlents in the guidance tube array and remo~red a~y interior irregulari-
ties. Sufficienty of the honing operation can be checked visually by sight-
ing with the eye along the bore of the array and noting when the bore
surfaces appear bright or shiny.
By way cf illustration of an effective tube assembly for
weaving with warp threads o~ 40's cotton at a density of about 72 threads
per inch of loom width, one might use one tube segment per 20 wa~p
threads.
The cize of the bore diameter o1E guidance tube T can signifi-
cantly afect the operation of the system if selected inappropriately. For
in6tance, with nozzles of various contours and throat cross-sectional
areas ranging between 8 and 32 mm2, a bore diameter of 3/4" works
well. If the diameter is reduced to 5/8'1, only the largest (32 mm2)
nozzle can project the weft the ~ull width of a normal loom, and the weft
tra~rel time is prohibitively increased. Apparently, the bore diameter
needs to be relati~ely large for relati~re easy entry and passage of the air
jet deli rered by the nozzle. First, the diameter of the tube bore in
relation to the outlet diameter of the nozzle, its spacing from the tube
ZS entrance, and the cone angle of the jet nlust be sufficient that the jet. substantially fully enters the tube entrance. Second, the bore should not
be too "tight" in relation to the air column moving therethrough, as other-
28 wise the column encounters excessive resistance in proceeding through
~21-
6~
the bore and "leaks" from the slot 49 and spacing between the tube
elernents. If the nozzle opening is sufficiently large to emit a massive
blast of air, the impedance of a "tight" tube can be overco~ne9 but the re-
Bi~3tanCe i5 still manifested in ~eriously retarding th¢ ad~rance of even
such a massive bla~t. It is not presently known how far the bore dia-
meter might be increased without approximating an unconfined environ-
ment for the weft and losing the advantage of the guidance tube; some ex-
perimentation may hence be indicated to establish the effective limits of
bore diameter ~riation in questio~able cases.
In the embodiment of the loom of the invention illustrated in
the drawings, the wet inserti~ nozzle N is mounted on the lay skeleton
39 in a fixed or stationary position and does not move in synchronism with
the compound motion of the weft guidance tubeO Thls permits a simplified
construction and the effectiveness of the tube or weft insertion is not
thereby significantly reduced. During the actual weft insertion phase, the
~rertical movement of the tube is virtually nil, and the axis o~ the inser-
tion nozzle is aligned, well enough within the axis o the guidance tube
over this pha6e. If desired, however, insertion no~zle N could likewise
be mounted on the movable supporting base 45 for the weft g.lidance tube
so that the axis of the nozzle would actually "track" the center line of the
guidance tube o~rer the com~lete operating cycle of the loom. Con-
ceiYably, this arrangement might afford some slight additional increase
in overall operating speed in permitting the weft insertion phase to be
initiated at a slightly earlier point in the cycle.
b. ~t~e~
- Where t'ne weft guidance tube is fixed on the lay as in
known air ~Jet insertion systems, the egress slot thereof has been so
28 located at a point on the upper peripheral portion o the annular lube
Z~65
segments that the path of the tube during withdrawal beneath the bottom of
the shed effected passive displacement c~f the inserted wet thread out of
the egress slot. That i8 to say, as the guidance tube with the inserted
weft thread therein passe~ from the shed, its thin individual annular
segment~ are able to slide betweenthe spaces between warp threads,
whereas the weft thread.itself cannot, being restrained by the array of
shed threads~ and must, therefore, remain within the shed as the guidance
tube segments swing c>utside the shed. Hence, the position of the egress
slot wa~ selected to facilitate passage vf the weft thread therethrough~
Pa~sive displacement of the weft can be used in the invention, i desired,
and while the optimunl location of the egress slot 49 for this purpose may
vary according to a specific design, it has been generally ound that a ~ ;
location at about 130-140 produces good results, starting with the plane
passlng through the axis of the supporting extensions 43 and counting in a
lS clockwise direction.
It ifi preferred in the inYention, howe~rer, that, instead of
acco~plishing displacement of the inserted weft threads passi~ely in the
above n~anner, a mechanism be provided to lift out each inserted weft :
thread positively through egress slot 49 in the tube segn~ent array. I~
this way, Inore direct control can be exercised ov-er the position of the
weft thread during beat up and displacement of the weft can be effected at
an earlier point in the beat up motion of the lay than would otherwise be
pos~ible. To this end, as shown in Figs. 1 and 3, a rock shaft 61 extends
across the width of the loom on the forward side of the lay channel 39 at
a location presenting a minimum of interference to access to the guidance
tube from the front of the loom. The ends of rock shaft 61 are journalled
for rotation in supports 63 projecting from the e~ls o lay char.~nel 39,
28 and beYeral thi.n weft lift fingers 65 are affixed to shafl: 61 at apprc.priate
-23 -
;5
intervals across the 6hed ~vidth including points adjacent the side edge3 o
the shed. Since the relative mass cf the weft i~ in any case e3ctremely
6mall, only that number of lift fingers 65 sufficient to keep the weft in a
reasonably straight condition during the lifting action is needed (four being
suIficient for a 40 inch lno~n, although more than four can, of course, be
used)r and lift fingers 65 can be ~uite thin so as to pass easily through
~he clearance spaces between the warp yarn6 of the shed. A bell crank
lever 67 is fixed to one outside end of the rock Ghaft and at the end of
that lever acts as a cam follower which cooperates with a cam track 69
constructed in a stationary part 71 of the loom frame. The cam track 69
is appropriately curved to impart the desired motion to the lift fingers
and includes in the schematically illustrated arran8ement in Fig. 1~ a
rearward inverted flat U-shaped arcuate portion 69a connecting with a
generally horizontal forward section 69bJ and thus, during weEt insertion
at back dead center, fingers 65 are retracted below the bore 47 of tube T
a6 ~hown in dotted lines in E'ig. 3; and as the lay starts to move forwardly
.
towaTd beat-up pcsition, the ca~n follower immediately rides up in the
car~ track portion 69a to rock the fingers 65 quickly upward to the pro-
jected solid line portion in Fig. 37 which lifts the weft vertically through
the egress slot 49 in the tube segment 41, ater which the follower drops
to retract the fingers 6S and enters the horizontal tlack section 69b to
hold the finger~ 65 stably in their retracted position durmg beat up.
When the lay returns to the weft insertion position, the fingers swing up
- and then down again to a retracted position below the bore of the guidance
tube ready for the next weft tc~ be inserted.
~he shape of the fingers can vary, bearing in mind that the
fingers must ultimately leave the shed between the warp threads in the
28 same manner as the guid~nce tube segments and ~lUSt be clear of the fell
_~4-
~52~65
at beat up position. At the same time, the ends of the ingers rnaking en-
gagement with the thread should be contoured to po~itively catch and hold
the thread during their lifting action to maintain good control over the
thread. Preferably, therefore, the rearward end of each lift finger
terminates in a generally V-shaped notch 71 to define a crotch into which
the thread will naturally fall aa the finger~ are lifted. The remainder of
the f~ger~ are arcuately curved to insure clearance with the shed threads
as the lay pivots forwardly to beat up position. It i8 also preferred that
the notch shaped rearward ends of the lift ~ingers lie in their retracted
position somewhat past in the rearward direction of the center plane of
the guidance tube; this locates the weft thread toward the rearward side
o the guidance tube bore rather than the forward ~ide and promotes
srnooth egress through e~it s~ot 49.
Under the impetus o the lifting mechanism, the weft thread
is displaced essentially ~rertically relative to the moYernent o the guidance
tube during beat up, and consequently, the port;on of the e~it slot snould
coincide substantially with the top point of the tube segment periphery.
In this way, the removal of the weft is determined by the positi~re lifting
- action of the lifting mechanism independently of the motion of the guidance
tube relati~e to the bottom of the shed.
c. Weft Insertion Nozzle Assembly
In order to achieve more precise and instantaneous
control over the flow of air from nozzle N for propelling the weft strand
- across the warp shed of the loom, a special nozzle and servo controlassembly has been devised. ~s shown in Fig. 4, this nozzle assembly
has an exterior casing 73 enclosing an interiol space, the casing being
preferably circular in shape, although its configuration iB not critical.
~8 One end of the c3.sing, at the let in Fig. 4, i9 sealed by a cover plate 77
secured via bolts or other iecuring mean6 79, a flexible diaphragm 81
being tightly clanlped around its margin~ betweerl the abutting surfacçs of
the casing and the plate and spanning the casing end. Within the interior
of t~e cas;ng is a two-part core generally designated 83 having the dual
functior. of delineating with t~ie interior wall of the casing an axially
elongated annular storage chamber 75 for containing a determined amount
of compressed air and forming between its two parts an annular divergent
passageway ending in a throat and exit opening.
The two parts of the core including an outer hollow sleeve 85
haYing a generally cylindrical ou$er wall 86 and a conical inner bore 87
and an internal generally naring trumpet-shaped plug 89 fittin~ in spaced
relation within the conical bore of the sleeve. The hollow sleeve 85 can
by means of an integral peripheral flange 91 at its outer (right) end 88 be
affixed with screws or the like 93 to the other end of the casing, to
complete the enclosure of the storage chamher space, although the sleeve
and flange could be formed separately and connected together. l~n any
e~ent, sleeve 85 i8 ~upported in cantilevel like fashion within casing 73
by a connection of Its outer end to the right end of the casing which also
seals that casing and (except for the no~zle orifice~, the in~er end of the
~leeve projecting free within the casing to adjacent its head end.
The free end edge of the hollow sleeve 8S is roua~ded as at 95
60 a6 to give a 3mooth nearly re-entrant curvature between the adjacent
margins of the conical wall 87 and the outer wall 86 of sleeve 85.
Preferably9 the section of outer wall 86 adjacent free end edge 95 is
de~eloped with a convex or somewhat bulbous cur~rature a6 at 97 to merge
more smoothly with the rounded free end edge 9S, while the correspond-
ing section of the interior wall of casin~ 73 projects radially inwardly
2~ along a concave curvature as at 99 to form therebetween a gradually
-26-
6S
tapering inwardly cur~ing annular mouth 101 at the end of ~torage
chamber 75.
The rounded free end edge 9S of sleeve 8~ makes abuttin~
contact ~ith an inner annular region of the diaphragm 81 and functions as
the seat of a "valve" which acts, as will be explained, to control the flow
of pressurized air from 6torage chamber 75. The interior wall 87 of tke
core slee re, after a slight initial convex curvature at its end merging
with the rounded free end edge 9$, has a gene;Lally uniform cvnical in-
c~ination and within this conical space the trumpet-shaped plug 89 is held
in fixed depending relation from the inner side of ca~ing head 77 by means
of fastening bolts 103 or the like, the center region of the diaphragm being
pinched between the flat end face of the plug and the casing head. I`he
outer wall 90 of the plug is spaced from thle conical inner wall 87 of
sleeve 85 and together define a convergmg annular supply passageway 105
1~ which gradually decreases in radius toward the supported slee~re end 91
.~ ~
and undergoes a slight narrowing in annular thiclcness adjacent the
rounded end edge 95 of the slee~re.
The apex end of tru~npet-~hapeci plug 89 terminates ~omewhat
sht)rt of the outer end of conical bore 87 of sleeve 85 and the remainder
;
of bore 87 constitutes a throat region 107 of the nozzle connecting with
the tapering annular passageway lOS. Throat region 107 extends tc an
orifice opening 108 in the supported end of ~lee~e 85 either in straight
..
~ylindrical fashion as 6hown in dotted lines in Fig. 4, or in flaring di~rer-
gent fashion, as indicated in solid lines, depending upon the type of nozæle
orifice opening that is desired, as will be explained.
- Passing through the interior of trumpet-shaped plug 89, and
- preferably in coaxial relation thereto, i~ a small axial pas~age 109 which
28 is occupied by a weft feed tube 111 extending the entire length of plu~ 89
27 -
8~i5
and projecting therebeyond at least to the plane of the outer end ace 88
of sleeve 85 and thus the outer limit of the bore 107 therein~ Preferably,
the strand eed tube 111 is constructed integrally with a T-shaped carrier
spindle 113 embedded in the plug and fastened thereto, for in~tance with
the same bolts 103 securing plug 89 itself to casing head 77. The feed
tube and carrier ~pindle make a sliding telescoping fit with the axial
passage 109 in the plug to facilitate ready removal of the tube for clean-
ing or replace~ent.
The interior face of casing head 77 facing diaphragm 81
opposite chamber 75 is relieved to define a shallow annular recess or
ma~ifold 115 opening toward and, in effect, closed by the dlaphragm and
this annular recess is connected by a line 116, shown in dotted lines in
Fig. 4, through a suitable port 117 in the casing head to a source of a
gaseous control medium, e. g., air tnot shown) for the purpose of con-
trolling the movement of the diaphragm. It will be understood that dia-
phragm 81 is exposed on its interior face to an annular area of predeter-
mined dimension formed by the shallow maniold 1 lS in the casing head.
Because the diaphragm will flex as required to balance the forces acting
on its two faces, its movement will be determined by the ra~tio of each of
Z0 these areas multiplied by the corresponding pressure of the media actingthereon. The asmular areas of mouth 101 and manifold 115 can be the
same; in that event, so long as the pressure of the control air in mani-
fold 115 is lcss than the effective pressure of the air in storage charnber
75, the diaphragm 81 will be displaced upwardly away from the rounded
end edge 95 of the core sleeve, establishing communication between
mouth 101 of chamber 75 and the beginning end of the annular passage-
way 105 to the noz~le orifice opening 108.
2% Since annu!ar passageway 105 begins on the radially inward
.,,, ~j
side of the rounded end edge 95 of eleeve 85 proximate the chamber mouth
101, it will be seen that the instant diaphragm 81 starts to leave its seat
on the rounded end edge and pressuri~ed air begins to escape from the
~torage chamber mouth 101, the effective annular surface area of the
diaphragm exposed to chamber pressure increases or "grows", which
acts to urther unbalance the forces acting to flex the diaphragn~ away
from its seat in a kind of avalanching effect. Consequently, the diaphragm
mo~es ~nrtually instantaneously from its seated closed position to the
limits of its unseated or open position, as allowed by its operating
characteristics, i~e. its flexibility, tension clearance, etc. Thus, the
opening action of the diaphragm "valve" of the nozzle of the invention is
extremely rapid a~d, indeed, it has been found possible to achieve an
operating response for the design in the order of one ms, in terms o the
time required for the pressure in the annular passageway 105 to reach
essentially the full pressure existing initially in storage chamber 75.
When it is desired to terlninate the now o air from storage
chamber 75, a control air pressure of sufficient magnitude is reimposed
on the exterior side of the diaphragm within the annular control manifold
115 and, it will be realized that if the effecti~e inner and outer annular
diaphragm surface areas are the same, a control pressure is excess of
the storage chamber pressure will be ~equired to restore the diaphragm
to its seated position in contact w.th the rc~unded end edge 95 of the core
sleeve. For this reason, the ratio of the annular or radial dimension of
the mouth 101 of the storage chamber is preferably substantially ~reater
than 1, e. g. in the order of 2 or more to 1, to reduce the difference be-
tween closing and opening control pressure. The selection of such
- bigher ratios of effective surface areas has the further advantage of
28 allowing a control pressure to be derived from the sarne source as the
-29-
~2~i!6S
~upply to the 6torage chamber 75, recalling that the control pressure it-
self need not be greater than sts:~rage chamber pressure, due to the
^'multiplier effect" of the unequal rat~o o the effective annular areas on
3pposite sides of the diaphragm.
Since the air in escaping frsm storage chamber 75 must under-
go a substantial cornplete reversal of direction in moving from chamber
mouth 101 into annular passageway 1û5 when the diaphragm val~e opens,
it iB desirable for mouth 101 and the entrance to the passageway 105 to be
contoured as already described to promote smooth transition in air flow
and clean communication between mouth 101 and passageway 105 without
sharp edges or angles in the walls and thereby reduce turbulence and
friction looses in air flow and minimize abrasive wear upon the diaphragm,
which must in operation undergo rapid oscillation between its closed and
open positions. For the same reasons, the surface of the casing wall and
head contiguous to the unsupported annular region of the diaphragm should
be Telieved slightly as at 119 and 12l 60 as to provide clearance space for
the free oscillation of the diaphragm. Otherwise, the life of the diaphragm
will be se~erely reduced. A suitable diaphragm material lS buna or neo-
prene rubber preferably reinforced with fabrLc.
The total volume o passage 105 and throat 107 i6 made as
small as possible consistent with other needs since the space do~,~nstream
of diaphragm 81 contains residual air after the diaphragm closes and if
too large prolongs the decay characteristics of the nozzle.
Undel some circumstances, an extenæion of the nozzle orifice
~5 opening 108 in the outer face 88 of sleeve 85 by means of a straight
cylindrically-shapcd barrel 121 (seen in dotted lines in Fig. 4) may be
useul. A central region of sleeve end face 88 can be recessed as at 123
2B for reception ~f one end of such a barrel 124 which can be ~ecurecl ;n place
by mean6 o bolts or other fasteners 125 and construction of the core
61eeve a.nd 6upporting flange in two pieces may sirnplify the design of this
as sernbly.
For versatility in use9 it is advantageous for the size and
contour of the throat area of a given nozzle assemWy to be variable and
~o~ this purpose the throat region of the nozzle sleeve is constituted by an
interchangeable insert lZ7 fitting with close tolerances into a socket 129
in the ~leeve end. Each insert can be bored to a gi~en size and contour to
allow the nozzle characteristics to be easily changed. No special sealing
or gasketing is needed at tolerances of + 1/1000".
The weft inserhon nozzle a6sembly N is mounted upon the lay
of the loom so that the nozzle can be "fired" at the proper point in the
operating cycle of the lay. As mentioned, the weft in~ertion no~zle could ~ -
be mounted or a compolnd movement similar to that of the gu~dance tube.
Howe~rer, this "tracking" relationship is not required, and very sati~-
factory reault~ have been achieved by mounting the nozzle in fixed relation
upc~n the lay with its axis approximately in alignment with the axis of the
interrupted guidance tubé when thç latter is -in dwell position at the extreme
rearward point of the lay motion.
Utilization of the diaphragm control "valve" just described,
eliminates the need for additional control valves in the supply of the
pressurized air to the storage chamber and the ca~ing wall can ha~e a
supply port 131 connected to an end of a supply conduit 133 (in dotted lines)
running to the main supply source not shown. A preferred embodiment of
2S a complete circuit of $he pres~urized medium will be described later.
Because of the dcsirability for the nozzle to be mounted
bodily upon the lay, the o~rerall size of the nozzle is preferably kept within
28 fairly modest proportio~s to avoid interference with other parts of the
_ J _
s
loon~, and this in turn imposes a limita.tion upon the permissible capacity
of the storage chamber 75 within the m~zzle. In the design shown, an
acceptable capacity for the storage space has been found to be 6 in ~ With
this limited capacity, the pressure that develops within passageway 105
5 upon opening oE the diaphragm valve may undergo early decay from a
maximum or peak value equal to the storage pressure within storage
chamber 75, and this decay in driving pressure can result in a reduction
in the effective thrusting force actually exerted upon the weft strand. In
the present preferred practice of the invention, the driving pressure is
sustained during the duration of the air pulse emitted from the nozzle
oriice as closely as possible to its maximum level, and this obj~ctive
can ~e accomplished by augmenting the storage chamber capacity with a
6upplemental reser~roir or accumulator 136 of substantially greater
capacity and connected to the 9upply pressure source as at 136. In this
way, the effective head pressure delivered lthe nozzle orifice through
passageway 105j which would otherwise decay as more and more of the
air escapes from storage chamber 75, is continuously replenished by
mean6 of fresh air supplied from reservoir 137. The reservoir should
be mounted as close as convenient to nozæle N, for example, below the
same end of 1:he lay as at 137 in Fig. 1, and connected to the nozæle by a
line 138 .
If the diaphragm were allowed to remain open a sufficiently
long time, obviously, the decaying effect would occur even with the
addition of the reservoir capacity but, with the limited operating times of
the nozzle of the invention, it has been ound that maximum operating
head pressure caff be sustained through the pulse with the addition of a
reservoir capacity of about 80 in3.
28 Mention has already been ~r,ade of the "~ultiplier effect"
,, ,~,.......... .
6~
achie~red by ~election of a ratio greater than 1:1 between the effective
working ~urface areas on opposite sides of diaphragm 81. This "multi-
plier effect" can be enhanced by means of an alternative noz~le construc
tiorl, a shown in Fig. 5, which for the most part is identic~l to the noz~le
of Fig. 4 and is given the same reference numerals. According to this
alternative construction, a casing spacer ring 139 is interposed between
the head end o the casing wall and the corresponding margins of casing
head 77 with the diaphragm 81 held therebetween, and an additional pilot
diaphragm 81' is clamped in place on the other side of ring 139 so that a
- 10 diaphragm is situated on either side of spacer ring 139 with a separation
~pace 141 therebetween. The central region~ of the two diaphragms 81
and 81' are secured in the desired spaced rela.tionship by means of a
companion spacer disc 143 clamped ~etween the nat face of conical plug
89 and tlie corresponding area of casing head 77 and in turn clamping the
ce-ntral regions of the diaphragms. Within the amlular hollow space 141
between the two diaphragms and the mutually facing side edges of the ring
and disc, there is disposed a free floating ring 14S which by virtue of a
laterally projecting flange 127 has a greater annular radius, and thus a
g~eater effective surface area, on its outer side 149 than on its inner
side 151, the annular dlmension of the inner and smaller side 151 of
floating ring 145 being enough to completely cover ~ia intervening dia
phragm 81, the mouth 101 of storage chamber 75. Thus, a smaller
control pressure applied against the outer pilot diaphragm 81' will serve
to control movement of the ilmer operati~e "valve" diaphragm 81 against
a given storage chaml~er pressure, and the ratio of the differential
annular areas 149, 151 of the floating ring thereto increases the "multi-
plier effect" exerted upon the operating diaphragm 81 as it will be seen
28 from the following rnathematical analysis.
,. ~
i
From the aforegoind general description, it will be appreciated
that an equilibrium condition will exlst on the two opposite sides of the
operating diaphragm 81 when the product of the pressure Pl times the
are3 Al on one ~u~face equals the product of the pressure P~ times the
area A2 on the other ~urface, and if the ~urface areas are fixed, this
equilibrium condition will become u~balanced when the pres~ure on either
3ide rises above or falls below its equilibrium value. This relationship
can be illustrated quantitatively by assuming a gi~ren set of dimensions
for the ef~ective wo~king areas of the opposite sides of the diaphrag~n
lO which set is in fact employed in a preferred embodim~nt of the invention.
Thus, it is assumed that the inner diameter of the floating ring 145 is
1. 5", the outer diameter of the inrler face 151 of rht ring is 2. 363", the
outer diameter on the pilot face of the rillg including the lateral nange
2. 523", the diameter of the circular point of contact of the rounded sleeve
15 end edge 95 with the operating diaphragm 81 (i. e. at the "seat" of the
val~e) l. 625", and the pressure (P3) wlthin the storage chamber 75 is 80
p.s.i The annular area on the pilot side 14~ of the ring can be calculated
by subtracting the area of the interior opening from the overall area of
t~e ring on the pilot side. Since the area is equal to~T :12, the overall area
20 of the pilot side of the ring is equ21 to 0.785 x (2.5Z3) in.2 or 4.999
sq. in., ~ile the area of the rmg interior equals 0.785 x ~1.5) Ln.2 or
1.767 sq. in., the difference between the bwo being 3.2 sq. m. which is
the annul æ area (Ap) of the pilot face of the rlng.
The total area of the operating face of the ring equals 0.785 x
25 (Z.363) m. or 4.385 sq. in., while the area delimlted within the end
edge 95 of the core sleeve equals 0.785 x (1.625) in.2 or 2.074 ~q. in. for
a difference of 2.311 sq. m. for the annular area (As) of the operating
diaphragm face which receives the force of the storate pressure.
In equilibrium condition, the
-34-
follawir,g equatiorl applies ~5;~5
P x A = P x A
p p s s
where Pp is the unknown pilot pressure in i~am ~old 115. Substituting the known
values for As, Ap, and p , p = 80 poS~i X 2 311 S~
pounds/sq. in. Therefore, as long as the pilot pressure is 57.2 pounds/sq. in.
or above, diaphragm 81 will be maintained in closed position.
On the other hand, as soon as the pilot pressure is permitted
to drop below the equilibrium pressure of 57. 2 pounds /sq. ~rl~,, diaphragm 81
will be displaced by the storage pressure Ps~ Instantaneous with the
moment such displacement occurs, the ~terior margin of the operating
diaphragm face, previously sheltered by the rounded end edge 95 of the
sleeve (i. e. the reg~ on of the face of diaphragm 81 inside the valve "se.at"),.
~ecomes.exposed to the force of the storage pressure Ps~ thereby en-
largillg the effecti~e area receiving P9 on the operating side of diaphragm
81. Specifically, the operating surface area as enlarged is equal to
~ 2. 619 sq. in. (the complete area of the inner side 151 of the ring 4. 385
. inO in less ~he-area of the interior opening~2.074 sq~. in.) amounting bo mor~than a ~25% iDcrease (i. e. 26. 3%) iD the effecti~e wc~rking area of the
operating side of the dlaphragm. Ob~riously, the product of the storage
2û pressure and this increased operati~g area overwhelmingly overbalances
the re3i3tance of the pilot pressure on the opposing diaphragm area,
causing the opening action of the diaphragm to become virtually instan-
taneous O
In order to restore the diaphragm to closed condition9 one
must impose a so~newhat greater pilot pre~sure which can be similarLy
calculated. Assuming that the storage pressure remains at 80 lbs./sqO in.,
the new pilot pressure Pp times the pilot area must exceed the storage pres-
sure (80 p.s.i.) times the enlarged operating area (2.619) sq. in. Therefore
-35-
' 2 69 in ~ g~5 '
P = 3 11 5~ in x ~0 lbs./sq. in. and Pp = 65.4 lbs~/sq. in. which
i~ the munlmun pilot pressure needed to restore diaphragm 81 to closed position
over ~he mouth 101 of supply chamber 75. Floating ring 145 is formed of
plastic or like low mass mQterial and is preferably held loosely m its oFerat-
ing position in spaoe 141 between the diaphragms by mY~ns of a st~bilizing
lip 153 projecting i~teriorly fram the inner end of casing spacer rm g 139,
the size of spacè 141 keing sufficient to allow limited free mcvemen~ of floatinc
~ing 145 axially of the nozzle, while restraining r~ng 145 against possible
lateral or rocking movement that might be an aberrant influe~ce on the
operation of diaphragm 81.
It will be ~ecalled that the weft strand feed tube 111 extends
thruugh casing head 77 and conically shaped core plug 89, projects beyond
the apex of the plug through the outer end portion of the bore 107 in core
slee~re 85 to a point at least o~en with the outer face 88 of that sleeve.
This means that the nozzle orifice opening 108 is necessarily in the shape
of an annulus bounde~l between the exterior wall of the exposed end of
feed tube 111 and the interior wall of the sleeve bore 107. It is an impor-
tant feature of the present in~rention co~x~non to all embodirnents OI the
weft insertion nozzle thereof that the area of the annulus at the point of
least diameter of bore 107 constitutes the minimum area in the entire
air flow path through the nozzle. The poin~ of the m;nimum area of the
air flow path defines the throat of the nozzle and a critical req~lirement of
the invention is the occurrence of a choking effect in that throat. Given
the re-entrant bend in the air flow path in the present nozzle, with the
stora~e, chamber 75 developed as an annulus around the bore 107 and i~s
delivery passageway 105 and the converging nature of passageway 105, it
follows that the poi;~t of ~ninimum flow area Occul s at the point at least
diameter in l)ore 107 in the illustrated embodiments (the total effective
-36-
6~
flow area of annular passageway 105 being a function sf its overall dia-
n~eter a.s well as its annular radius). Vl~here other design conigurations
are employed, the same result rnay not inherently follow but design of the
~ozzle in any case will have to comply with this requirement.
S In addition, where the supplemental reservoir 137 is employed
to augment the flow capacity of storage chamber 75 and thus maintain the
ull head pressure being delivered to the no~zle orifice, the conduit 138
connecting between the outlet of the supplemental reservoir and the port in
the casing wall, together with these ports themselves, must have an
effective nOw area larger than the effective nOw area of the nozzle throat.
Since the duration of the air flow during weft insertion will ordinarily con-
sume only a minor fraction of the total working cycle of the loom of the
invention, the flow late capacity of 6upply conduit connecting between the
.
pressure source and the storage chamber, or the supple~nental reservoir,
1~ when present, need not fill this ~ame requirement, provided, of course,
that in the~ available replenishment time (between nozzle firings), the
amount of air delivered from the supply ~nain to the reservoir andlor the
storaee chamber is adequate to restore their initial filled condition.
d. Self-Threadin~Nozzle Feeder
The weft feed tube of ~he weft insertion no~zle could, of
course9 be threaded initially by hand using a threading leader of sufficient
rigidity as to be insertable into the bore of the feeder tube for drawing the
leading end of the weft throughout. However, to facilitate noz~le thread,
preferably the no7zle is provided with a weft threading attachment seen
to the left of the nozzle itself in Figs. 4 and 5. This attachrnent consists
of a small cylindrical casing 161 penetrated by an axial Ieed bore 163 of
cufficiellt diameter to reely pass the weft to be threaded into the noz71e
28 and having a trumpet-shaped inlet opening 165 in one of its end aces.
The other end face of the casing fits in abutting contact
against the exterior face of the head 77 of the nozzle casing
with its feed bore 163 registering with the bore 112 of the
nozzle feed tube 111. Surrounding an intermediate section of
feed bore 163 is an annular aspirating chamber 167 having
forwardly flaring end walls 169, 171 and communicating with
the interior of feed bore 163 by way of a small forwardly
directed annular opening 173 in its end wall remote from
inlet opening 165. By connectin:g the aspirating chamber
167 to a source of pressurized air a confined high velocity
annular stream of air is projected forwardly~into feed bore
163, creating a negative pressure and resulting in an aspirating
effect in its inlet opening 165. Thus, when the free end of
the weft is brought into the vicinity of inlet opening 165,
it is sucked ~nto that opening and projected forwardly
: through the feed tube 111 of the injection nozzle.
~: ~ To simplify construction of the self-threading attach-
ment, a cylindrical socket 175 having a convexly flared end
face is drilled into the casing and a cylindrical plug 177
.
of reduced axial dimension and having a concavely flared
end face is press-fltted into the socket leaving an axial
~ clearance to form chamber 167. An axial aperture 179 passea
: through plug 177 and its:outer end is flared outwardly to
form the trumpet-shaped inlet opening 165. A tubular insert
180 fits tightly into axial aperture 179 and extends about
the depth of the socket, the insert having an exterior diameter
of the flared socket wall to define with the open space of
the socket the annular chamber 167 having the small annular
:~- clearance 173 at its inner end. A supply port 181 connected
by a conduit 183 to a source of pressurized air tnot seen)
is passed radially through casing 161 int~ annular chamber
167, and as pressurized air flows from the annular chamber
-38-
!365
into the bore 163, a ne~ative pressure is created in the
interior of the tubular insert 180 to positively aspirate
the strand into its
:: ' :
:
.:
:
'~
.
,
. "
-38a-
' ,
trumpet-shaped inlet opening.
Alignment of the self-threading attachment with the nozzle in-
let can be facilitated forming bore 163 by means of a tubular insert 185
projecting outside the casing 161 for a tele6coping fit with an outer
portion of the feed tube lll if the nozzle itself.
In operation, the air pres6ure supplied to aspirating chamber
167 may be maintained continuously at a level substantially below the
operating pressure level of the nozzle, 6ay in the order of 10 to 20 psig.
e. Pilot Pressure Control System for Insertion Nozzle
As previously indicated, the present invention imposes
very stringent requirements upon the operating characteristics of the
diaphragm val~e in that the valve must have the capacity of responding in
precisely reproducible fashion at a minimum frequency of 900 cycles per
Tninute combined with an extremely short actuation time, in the order of
oné ms, and a special control system is provided for actuating the dia-
phragm ralve in accordance with these requirements. The use of a
directly operating Golenoid valve for controlling pilot pressures acting to
actuate the diaphragm valve of the invention, for example, is out of the
question at the present state of the valve art. There are available sole-
noid driven control valves which are capable of a response time in the
order of one ms, but these valv-es can pass only an extremely small
amowlt of fluid in a given time, and this low transmission capacity would
introduce such excessive impedance that the required rapid reaction of
the diaphragm valve itself is impossible. Moreover, such fast acting
solenoid valves are effective in only one direction and are characterized
by a much slower response time, in the order of 5-6 ms, OJl their return
stroke. Presently available solenoid valves with an air transmissiol1
Z8 capacity sufficient for purpose3 of the present invention have a response
-39-
~Z~365
t;me in the order of 10 ms in each of their operating directions which
would irnpose a minimum of 20 ms "delay" for each operating cycle and
consequently inherently preclude the achievement of shorter response
time s .
1) Electricai Embodiment
One e~nbodiment of the nozzle control unit in accordance
with the present invention, based on electrical principles is illustrated
schematically in Fig. 6 and utilizes two separate solenoid Yalves 185a,
: ~ 185b (re~resented diagrammatically) of suitable air transmission capacity
connected to the opposite sides of a co~slrnon shuttle valve 187 which in
turn is connected at its output 1~9 to the pilot port 117 o the casing head
77 of the weft insertion nozzle. Upon electrical energization, each sole-
noid valve moves between a supply position connecting a suitable source
` ~ of pressurized alT to its outlet and an e~haust or "dump" positlon
:15 connecting its outlet to the ambient atmosphere, both valves 185a, 185b
being biased to exhau-st position and s'o shown in Fig. 6. The outlets ~'
~: :
: ~- 186a, 186b of the respecti~re solenoid valves communicate w~th opposite ~ .
ends of shuttle valve 187. Each side of the shuttle or piston 188 of ~7alve
:
87 is effective by means not sl~own to close the correspondîng end of the
valve when unbalanced to that 'end. The outlet port 189 from shuttle val.ve
.' 187 is located at its midpoint so that the shuttle or piston clears the out-
let port in either o~ its extreme end positions. Hence, :when the shuttle
is in each extreme position9 the outlet of one solenoid valve is in ull -:
communication with the ~huttle valve outlet while the outlet from the ot~er
solenoid is closed ~y the shuttle. In this wa~, the shuttle valve isolates
each solenoid valve from the other.
Thc function of this arrangement is illustrated schernatically
Z8 by l:he wave oras in Fig. 7. ~s indicated, each solenoid valve A, B
_40 -
:
6~
moves between a supply position in which its wave form a, b i~ high and
an exhaust pc>s;tion in which its wave form i8 low~ the transition from
these two positions being shown as a line sloping at an angle determined
by tke response time or lag of the solenoid. Wa-re form c represents the
~huttle va1ve~ side b of th~ shuttle being closed when the wave form is low
and side a being closed when the wave form i6 high. The response of the
diaphragm val~e appears in wave form d, being clo~ed when low and open
when high. The actual nozzle output pulse is sho~vn in wave form e, the
nozzle being "off" (no air output) when orm e is low and "on" (air pulse
delivered) when form e is hlgh. It is assumed that at the starting point,
the diaphragm valve of the nozzle itself i3 iI-l closed or seated position
(and wave form d is low), while ~olenoid control valve A is in its supply
po~ition ~and wa~e form a i5 high~ connecting the supply pressure source
to the "a" side of the shuttle Yalve, thus biasing the shuttle to its "b" side
lS (and wave form c is low), closing off the outlet from the "B" solenoid
valve, and establishing conne~tion between the outlet of solenoid valve "A"
and the shuttle ~alve outlet which applies control or pilot pressure to the
control side of the nozzle ~perating diaphragm valve to maintain that
valve closed (and wave form d i6 low). Solenoid control valve B is at this
time situated in its exhaust or dump position (and wave form b ia low).
~Ln operating cycle is initiated at a time tl, indicated by a dash-dot line,
to open the diaphragm valve o the nozzle by releasing the control pressure
thereon, and solenoid control valve A is shifted electrically to its e~haust
po~ition, while solenoid valve B rem~ins in its exhaust position. As a
consequence, the shuttle valve remains at its "b" side position, but the
control pre 5 sure actin g on the diaphragm valv e now be gins to be cxhausted
to the atmosphere through the c~haust of solenoid A at some rate deter-
28 mined by the response rate of the solenoid valve as well as the inherent
~ ,; . ..
- ' ' - .' ~
~ ~;Z865
impedance, i. e. line resistance, etc., in the various connecting lines.
There~ore, wave form a begins to fall at a sloping rate. When the control
pressure acting on the diaphragrn falls below a certain calculated lelrel at
a t;me t2, the supply pres~ure in the storage chamber of the nozzle will
then exceed the control pressure, forcing the diaphragm immediately into
open position and wave form d goes high. The opening of the diaphragm
~ralve admits pressurized air from the air storage chamber to the nozzle
(and wave form e starts high at time t2).
The diaphragm valve rema;ns open, with the weft-projecting
air pulse enlitting from the nozzle, ~o long a~ bs~th solenoid valves A. and
B are in their exhaust (i. e. low) position; and in order to return the dia-
phragm vaive to its closed position and end the nozzle pulse, solenoid
control valve B is actuated electrically at a time t3 to shift from its ex-
haust to its supply position. Th~s, ~solenoid valve B, as seen in wave
form b, makes its transition from exhaust to supply position~, shown by
the sloping line, the slope or rate of which is again determined by the
response time of the valve and the impedance of the system as before.
Since the opposite of "b" side of the shuttle valve iB at this point in
communication with the atmosphere, becau9e of the exhaust position of
solenoid valve A, there i8 no resistance to the shifting of the shuttle to
thc "a" side position (and wave form c abruptly goes high), and pressure -
begins to build up within the control side of the operating diaphragm of
the insertion nozzle.
At a certain time t4, the control presstlre will exceed the
;- 2S pressure in the storage chamber 75; and when this occurs, the diaphragm
moves from its open to its closed position (and wave Iorm d goe6 low).
- Since there i5 no "avalanching" effect in the closing of the diaphragm
Z~3 valve, as occurred in its opening, the closing response of the diaphragm
-42-
,.
~2~65
~alve is inherently somewhat ~lower than its snap action opening response
(as seen in wave form d~3 but thi~ has no significant effect on operating
efficiency ~ince some decay iB unavoidable in exhausting residual air from
within the no~zle passageways. It i3, howe~rer, de~irable that the cls)sing
response not be excessively long in order to minimize unnecessary con-
sumption of air during each operating cycle, and the alternative nozzle
embodiment of Fig. 5 i~ preferred becau~e it allows the diaphragm to
clo6e at a lower level of control pressure and consequently with a higher
rate of response. As the diaphragm valve closes, the nozzle pulse is
shut off (and wave form e starts low at time t4).
The æignals used for controlling the actuation of the solenoid
control or servo ~alves ~ and B of the embodiment of Fig. 6 are derived
electrically as also shown in Fig. 6. Each operating cycle o the control
system must occur in timed relation to the operating cycle of the loom
it~elf. The control impulse for initiating each control cycle is preferably
derived from the driving crankshaft o the loom itself. To this end, a so-
called Hall efect switch 189 is associated with the crankshaft ~not shown),
this switch consisting of a magnetic~lly operated switch arranged at a
point adjacent the crank3haft and a small magnetic element carried OD the
periphery of the cranksha~t itself so that upon each rotation of the crank-
shaft, the magnetic element passes the switch and activates it to trans-
mit a control signal.
From the preceding discussion of the actuation of solenoids
A and B, it will be realized that means must be present to actuate each
solenoid control valve 3eparately at preselected times which desirably
are adjustable relative to one another. Also, the timing of the generation
of the control signal during the loom operating cycle needs to be adjust-
28 able to regulate the timing of the firing of the weft insertion gUII and
-43 ~
. .
2865
achieve insertion of the weft at the optimum point in the loom operating
cycle. This adjustability could be achieved mechanically by changing the
location o either the switch or magnetic actuator of the Hall effect switch
relative to the erankshaft psriphery, but to do this conveniently would re-
quire a rather complicated mechanical arrangement, particularly since
the loom crankshaft is ordinarily in a relati~rely inaccessible position.
Moreover, a high degree of precision, i. e. within 1/3 of a degree of
rotation would be difficult to achie~re in this way; hence, an electronic
arrangement system for regulating the control signal is much preferred.
To this end, a master d~lay timer 191 i6 eo~nected to the Hall effect
~witch and consists of a plurality of, preferably tnree, decade counters
(not shown 6eparately), each adapted to count fro~n 0 to 9 in interval~ of
1 ms, ar~d including an associated control dial for setting purposes, the
counters being ganged together so as to count continuously from 0 to 999
ms to give an accuracy of 1 ms. Upon receiving the initi~l control
signal from the Hall efiect switch 189, the master delay timer 191 begins
its counting operation and count~ for a gi~ren number of ~nicroseconds as
set on the control dial of its decade counters and after concluding such
count, emits a control signal. In this fashion, the master timer, in
effect can delay the transmissioIl of the initial control signal in ncrements
of 1 ms up to 999 ms for each loom operating cycle.
The control signal from master delay tirner 191 is trallsmitted
~eparately to each of the solenoid valves by means of separate solenoid
control timers 193a, 193b, which are sirnilar in arrangem~nt and in
function to master delay timer 191, making possible the regulated delay
of the timer control signal in increment~q of 1 ms up to 999 ms (or a
srnaller or greater total if a coarser or finer degree of control is desired~
2~ 2nd deper.ding upon the delay interval set on the dials of the solenoid
-44-
.
~;2~36S
timers, each such tin~er will transmit a control pulse at a pre-selected
given interval after receiving the common control pulse from the master
delay timer.
The initial control signal generated by the Hall effect switch
i8 of very brief duration and is not sufficient to maintain the actuation of
each of the solenoids for the period of time that the valves of these sole-
noids n~ust remain in open and closed po~ition. Consequently, the con-
trol signal from each of the solenoid delay timers 193a, 193b is delivered
to a pulse duration timer 195a, 195b which functionq to prolong or
"stretch" the pulse for a given period of time. The pulse duration counter
iB composed of a gang of two oi the decade counters mentioned above to
giv~e a ~apacity of 0 to 99 ms delay in;mtervals of 1 ms (although a hiaher
precision i6 obviously po sible with add1t1onal decade counters if desired).
A180, the power of the control signal is ord;narily of a low magnitude, as
;: :
is true for most i'logic" circuits, ~nd is ins~ufficient to electrically drive
the~solenoid. Each signal must, therefore, be amplified by a driver
:
amplii r 197a, 197b which swStches between high and low, i.e. on and ~off,
conditions in respon6e to the high or low state of the control signal,
::
supplyiDg sufficient power to the solenoid valve for effective electrical
actuation thereof.
It will have been understood from the aforegoing description
that a highly flexible and precise control 6ysten~ for the weft insertion
ozzle is obtained by the just described arrangement. First, the opera-
tion of the diaphragm valve i9 independent of the response times of the
individual solenoid servo valves either upon actuation or de-actuation.
Since separate solenoids determine the application and release of the
control pressure, the lag of the solenoid in returning to starting position
28 is immaterial fro~n the standpoint of any control function, provided, of
,. . . . . . . . .
~ ~;2~3~5
course, that the lag of the solenoid is not so great that it cannot be return-
ed to ~tarting position in ti~ne for the next cycle Secondly, while the
actuations of the solenoid valves are caused fundamentally by crankshaft
rotation of the loom, and are hence directly related to the loom operating
cycle, the actual timing of such actuation is adjustable with respect to such
rotation, giYing complete flexibility in regulating the timing of weft in-
~ertion relative to the looln cycle. Finally, the timing of the actuation of
each solenoid relative to the other i9 precisely variable and the duration of
energization of each solenoid is independently adjustable w;th a good degree
~0 of accuracy.
2) First Mechanical Embodiment
The control system s~f the invention should h ve the capa-
,
bility of operating many millions of cycles without a failure; and while the
electronic ystem described above i5 as durable as is possible with elec-
~i5 tronic components, it may be preferable to utilize instead a mechanical
control system which tends to be more reliable over long periods of opera-
tion. One alternatiYe embodlment of the noz~Le control system based on
~; ~ mechanical principles is illustrated ir. Figs. 8 and 9. In general, the
mechanical control embodiment includes a pair of valve spools which are
mechanically coupled together and to the drive systenl of the loom, one
6pool being capable of adjustrnent in its peripheral relation relative to the
other. Each of the spool~ rotates within a housing and includes on its
periphery supply and exhaust apertures located at circumLerentially and
axially spaced points thereon which during spool rotation are brou~ht into
communication with a supply and exhau~t port, respectively, in the housing.
These ports are in communication via a connecting conduit wiih a corr~non
shuttle valve, similar to the electrical embodiment, so that upon rotation
28 o the spools, the application and release of pilot pressure to the pilot or
-46 -
..
~"~6S
control side of the operating diaphragm valve of the weft insertion nozzle
i5 regulated.
More specifically, the mechanical sy~tem of Figs. 8 and 9 in-
cludes a housing block 198 represented by dotted lines in Fig. 8 and pene-
trated by two large spaced parallel cylindrical apertures 199a, 199b
~Fig. 9). In each such aperture is fitted a hollow air regulating spool 201a,
201b with a clearance of about . 0003" which is sufficiently tight to sustain
a moderate air pressure. To minimize wear and avoid the necessity for
bearings, each spool 2~1a, b, i9 connected in itB hollow interior 202a,
202b to a coaxial drive shaft 203a, 203b by mean~ of a floating connection
which caD take the form of an elongaged V-shaped "hair pin" 20Sa, 205b
having the apex 206a, 206b of the `V secured to the free end of the drive
shaft and lateral extensions 207a, Z07b at the ends of the ~T engaged in
recesses 209a, 204b formed in the interior of the bore of the spool about
midway of its length. With this flexible coupling, the spools will rotate ;~
bodily with shafts 203a, b, while being free to assume a natural centered
position within their respective enclosures, due to the flexibility of the
: :
air spring as well as their pivoted connection thereto. Other types of
~: :
;~ floating eOUpliDgæ could, of course, be substituted.
~ Each drive shaft 203a, b~ is journaled in bearings 211a, 211b,
in an end wall of the housing 198 and includes an exterior e~tension 213a,
213b, carrying a pinion 215a, 215b, and both pinions are interengaged to
rotate in sync~ronism. The driving force for the two pinions can be
supplied by a gear carried directly on the crankshaft of the loorn or, if
preferred, the output gear of a mechanical transmission driven from a
gear on the loom crankshaft and engaged by one pinion, the driving gear in
any case being designated 216 and rotated with a shaft 217. To permit the
28 rclative peripheral position of the two spools to be adjusted, one pinion
-47 -
, ., . ~ . . , . ~ . .
5! ~ ~6 5
215a i6 connected to it~ drive ~haft extension 213a through an adjustable
coupling which ~nay take the form of a pair of abutting discs 219, 220
cerrated on their adjacent cc~ntacting faces for mating engagement, the
disc ?19 being integrally united to pinion ZlSa which rotates freely on its
5 shaft exterl~ion 213a and the disc 2Z0 being slidingly keyed to the project-
ing end of the shat extension and biased against the pinion disc 219 by
means of a cornpression spring 221 held at its free end with a split ring -
fastener and washer 223. By disengaging the key0d disc 220 from the
pi~ion disc Z19 against the forc~ of compression spring 2Zl7 shaft 213a
can be tuTned independently of its drive pinion 21Sa and thus the rotary
position of the other fixed spool 201b. The ends of the apertures i 99a, b,
in the spool housing are open to vent the hollow bore of each spool 201a,
b, to the atmosphere.
The housing 198 is constructed with a series of air passage-
ways for cooperation with spool valves 201a, 201b, and in Fig. ~, for sake
of clarity and conveIlience, these passageways are developed and ahown as
external conduits (the housing itself being indicated orsly in dotted lines),
although in reality these passageways would be formed internally of the
housing). The beginning of the passageway i6 an inlet openirlg indicated at
225 which is connected to a source of pressurized air (not shown), and in
turn connect~ with a supply conduit 227 from which branrhes eupply port~
229a, 229b (see Fig. 8), one for each of the two spools. At a point along
ats length in axial registration with th~ associated supply ports 229a, b,
each of the spools 201a, b, carries a peripheral supply recess 231a, 231b
which extends around the periphcry of each spool for a given arcuate ex-
tent less than 360, say 270, the remaining arc of the spool periphery
at this point being solid or unrelieved, as at 233a, 233b (only the latter
28 of v~hich can be seen in the drav~ings). When one of the supply recesses
-48 -
31a, b, coincidesi with its corresponding supply port7 air under pressure
is admitted rom supply line 227 to fill the ~upply recess, while, contrari-
wise, when an unrelieved wall portion 233a, b, coincides with a supply
port9 the supply port is blocked as to air flow by reason of the tight fit of
5 the spool iD 'che housing aperture. At the same axial or lengthwiise point
along each spool but spaced peripherally frorn the supply ports 229a, b,
is a delivery port 235a, 235b (see Fig. 9) which connects by a delivery
line 236a, 236b to the corresponding side of a shuttle valve similar to the
sihuttle valve 187 of the electrical embodiment and designated 187', the
shuttle val~e here as in the other embodirnent having its outlet 189'
connected to the pilot or control port 117 of the insertion nozzle. Thus,
when a spool supply recess 231a, bj filled withpressurized air, coincides
with a delivery port 235aj b, air flows into the delivery port and through
the delivery line to the shuttle valve 187~ while when an unrelieved peri-
pheral portion 233a, b, coincides with the delivery port, that port is
blocked.
Between its delivery port 23Sa, b, and connection with the
~huttle val~e, each delivery line 236a, b, branches as at 237a, 237b
(Fig. 8) to form an es~haust line terminating in an exhaust port 241a, 241b
(not seen in Fig. 9) in peripheral alignment with but displaced axially
along the spool length from the corresponding delivery port Z35a, b. At
a point along each spool length axially aligned with the exhaust port 241a,
b, an exhaust recess 243a, and 243b is formed on each spool periphery
and each such exhaust recess has a peripheral extent co~nplementary with
the peripheral extent of the del*ery recess 231a, b, with the remaining
periphery solid or unrelieved as at 245a, b. That is to say, the arcuate
extent of each exhausit recess 243a, b, equals the arcuate extent of the un-
28 relieved surface portion 233a, b, interruptin~ the ends of each delivery
-49 -
365
recess 231a, b, whereas the remaining unrelieved portion 245a, 24Sb of
the spool periphery at each exhaust recess matches the peripheral dimen-
sion of the delivery recess 243a, b, and the interior bore 202a, b, of the
associated spool so as to vent the recesa space to the atmosphere. Thus,
when one of the exhaust ports 241a, b9 s:oincide6 with its exhaust recess
243a, b, communication is established between the shuttle valve 187' via
deli~rery port 23Sa, b, exhau6t branch line 237a, b, exhaust port 241a,b,
exhaust recess 243a, b, and exhaust vent 247a, b, and the ambient atmos-
~ phere. On the other hand, when the unrelie~red peripheral portion 245a, b,
of the spool coincides with an exhaust port, that port is blocked.
As described before, the relative starting positions of the two
rotary spool valve6 will be different, being shown as 180 out of phase in
Figs. 8 and 9, and can be adjusted as desired. It follows that as each
spoo1 valve rotates, supply and delivery ps~rts for a given spool will be in
communication with one another via the comm~n delivery recess 231a, b,
for a period of each revolution determined both by their peripheral
; ~ separation and by the peripheral length of the deli rery recess, and while
such communicatit>n exi ts, pressure is delivered to the corresponding
~ide of the shuttle valve 187'~ whereas the exhaust port 241a, b, during
this period will be blocked. The eæhaust port 241a, b, on the other hand,
will be in communication with the atmosphere ~thro~agh the exhaust recess
243a7 b, vent and ~pool bore) for a period according to the peripheral
length of exhaust recess 243a, b, during which period the corresponding
side of the shuttle valve will be exhausted. During the latter period, the
corresponding delivery port is blocked by the solid peripheral surface
233a, b, complementary to the exhaust recess extent at their co~mon
axial position. While either of the delivery port 235a, b, or supI)ly port
28 229a, b, of a given spool is blocked, delivery of pressure to the
:, .
_50-
corre9ponding side of the shuttle valve is precluded, even though the other
port is in communication with the supply recess. When the supply and
delivery ports are both open to the delivery recess, the exhaust port for
that 6pool must be blocked. The peripheral positions of the respective
spools are independently adjustable so the abo~e actions can be arranged
to occur in a desired sequence.
In thè aforegoing construction, each spool receives the radial
thrust from the se~Teral flows of pre~surized air and, in time) the radial
biasing force of the pressurized air would cause unacceptable wear of the
spool unless compensatory measures were adopted. For this purpose,
counterbalancing supply groo~es 249a, 249b are provided on each spool on
the opposite axial sides of the supply recess, the aggregate axial thickness
o~ these grooves and their peripheral dimen6ions being each equal to that
~; of the 6upply groove but 180 out of phase. That is, the unrelieved portions
251a, b, between the ends of each p~ir of counterbalancing supply grooves
249a, b, is exactly diametrically opposite to the unrelieved portion 233a,
b, between the ends of the corresponding supply recess situated between
them. The ~upply line 227 from the pres6ure source includes extensions
253a, b, which are branched at their end as at 255a, 25~b for communi-
cation ~ith the respective counterbalancing grooves 249a, b, to supply air
those grooves in balancing opposition to the air impinging upon the supply
recess 231a, b, rom its supp1y port.
Similarly, counterbalancing exhaust grooves 257a, 257b are
provided on each spool periphery equal in arcuate extent and aggregate
axial thickness but opposite in peripheral location on the opposite sides of
exhaust recesse6, and e~haust line extensions 256a, 259b open onto these
grooves to apply counterbalancing pressure.
28 In addition to independent adjustmeDt o the spool relative to
,2B65
~o one another, the starting position of the entire ~pool assembly should
also be adjustable relative to the crankshaft of the loom to vary the over-
all starting point in the loom operating cycle (analogous to the master
delay ti~er 191 of Fig. 6). To this end7 the housing for the two rotary
valve spools 201a, 201b (which could, of course, be made separate instead
of common) is carried by a supporting plate 260 mounted for pivotal move-
ment around the shaft 217 of driving gear 216 (i. e., the loom crankshaft
or an output gear of a transInission coupled thereto making one revolution
per lLoom cycle) and plate 260 can be adjusted on the fixed support 261
arcuately relative to the driving gear within the limits provided by an
arcuate adjusting groo~re 261 and butterfly nut 263 therein. By properly
locating spool support plate 263 at the start of an operation, the starting
position of the fixed spool relative to the crankshaft position can be ad-
justed so as to give a measure of flexibility in setting the timing of the
firing of the gun in relation to the loom operating cycle. In the embodin~ent
hown? the range of adjustment is less than 100%, but since the interval in
the loom cycle during which weft insertion is possible is only a fraction of
the overall cycle, 100% adjustment is not n~eded as a practical matter,
and a degree of adjustment equ~lling about 20 of rotation is ~uite adequate
;~o in practice. If more latitude is needed, the driving gear can be readjusted
in rotary po6ition.
As in the electronic control embodiment of Fig. 6, the control
functions of opening and closing the diaphragm valve are effected in the
mechanical ernbodiment by indi~idual instrumentalities which operate
separately but in determined adjustable time~related fashion, one of t~e
spools functioning to release the control pressure from (and open) the
- diaphragm valve while the other spool functions to apply control pressure
28 to (and close) that valve~ Specifically, it is the rotation of the first or
~ r
865~
ieading spool into supply position with ~oth it~ supply and delivery ports
opening into itæ ~upply recess that initiates application of the: control
pressure to close the diaphragm valve - the subsequent rotation into supply
pOSitiDn by the second or trailing spool is immaterial (except $o position
She sec~nd spool for eventual movement to exhau~t position) as is the
rotation of the first spool into exhaust position. Conversely, it is the
rotation of the second or trailing spool into exhaust position while the
first spool is already in exhaust position that initiates release of the con-
trol pressure to open the diaphragm ~alve - the prior location of the first
~10 spool in its exhaust position is imrnaterial except to position it for even-
tual movement to its supply position.
The shuttle valve shifts in position in passive response to an
unbalance in pressure applied to its sides by the delivery conditions of the
two spools and functions to permit only one spool at a time to deliver
oontrol pressure to the diaphragm valve. When the effect of a change in
the rotary po6ltion of a spool i5 merely to bring the pressures on the
oppoæite sides of the shuttle valve into eq~lilibrium, whether such
pressures be high during deli~rer~ or low during exhaust, the shuttle
valve holds its existing position.
The maximum period possible between release and re-
application of control pressure to the diaphragrn ~ralve, and hence the
period the diaphragm valve remains open ~disregard;~g lag due to im-
pedance losses), OCCUTS where the two spools e~actly coincide in peri-
pheral position and equals the time equivalent of the arcuate length
Oi.e. in degrees of rotation) of the exhaust recess at a given speed of
- spool rotation. However, exact coincidence of the two spools would be
the fiame as a single spool and would normally not be used. The arcuate
28 length of the exhaust recess does obviously fix the maximum time of
-53-
, . , , . ~
i5
pulse duration and should be selected with this in mind. By shif~ g the
starting rotational position oI one spool relative to the other, the relation
in time of the two control functions can be changed and the duration of the
exhaustion period and thus of the nozzle pulse can be varied up to the
available maximum. The diaphragm valve does not open exactuly sirnul-
taneously with the rotation of the second spool into exhaust position but
lags somewhat therebehind since the control pres~ure must drop to some
critical level and the rate of pressure drop in practice i9 deter~nined by
the impedance of a particular system and must be established experi-
mentally for that system. Once established, it remains constant in re~
lationship to spool rotation and thus, the actual timing in practice of the
actuation and de-actuation of the nozzle Yal~re is fixed by the spool
rotation. After a preliminary adju~tment, both spools rotate continuous-
ly in synchronized relation to the operation of the loom and ts each other.
The response of the mechanical embodiment of Figs. S and
9 i~ identical in principle to that of the electronic embodiment of Figso 6
and 7, except that the mechanical embodiment includes an intermediate
~dwelll' or hold condition represented in dotted lines in Fig. 7, not
present in the electrical embodi~nent, in which the spool valsre is neither
actually applying nor exhausting pressure but simply nlaintains whatever
condition existed previously~ SpeciMcally, assume that for each spool
he exhaust recess 243a, 243b extends through an arc of 90 of rotation
and the supply recess 231a9 Z31b is complementary thereto and exlends
over 270 of rotation. Assume also that spool A is rotating clockwise,
while spool B is rotating counterclockwise as indicated by the arrows in
Fig. 8 and that the ~upply port lor each spool is situated 90 in advance
of the delivery port relative to the direction of rotation. Finally, a~sume
28 that spool B is initially rotated a~5 in it~; directic~n of rotation ahead o
_5~-
- . ;
365
spool A and that the ~tarting point corre~ponds to tirrle tl in Fig. 7.
As a poînt of reference, Fig. 10 is a diagrammatic cross-
sectional Yiew taken through the control spools of Fig. 8 in their starting
position, the sectional line being such aa to show both the supply recess-
es 231a, b, and the e~huast reces6es 243a, b, in relief notwithstanding
their actual axial displacement from one another, the transition between
the supply and exhaust recesses being indicated diagrammatically by a
thln solid wall designated x, with each exhaust recess being shown open-
ing to the epool bore while each supply recess iB closed by the spool wall.
The line connecti~g between each spool in Flg~ 10 with its side of the
shuttle ~alvç 187i is designated both as a delivery line 236a, b, and an
exhaust line 241a, b, since the deIivery a~d exhaust lines are in the same
peripheral location and are in open communication with one another. As
appears iZl Fig. 10, the starting position of spcol A i9 rotated 135
counterclockwise from ihe position of the leit spool in Fig. 8J while the
~tarting position for spool B is rotated 90 counterclockw~6e from the
right hand spool itn Fig. 8. In these positions, 6pool B is already in ex-
haust condition~ the B eæhaust port 241b being midway of the B exhaust
recess 243b (and wave Iorm b in Fig. 7 is low); whereas the exhaust
recess 243a for spool A has just been brought into coincidence with the
exhaust port 241a so that the A spool is just beginning to exhaust (and
waYe form a has jus$ gone low). The shuttle valve is in its "b" side
position (and wave form c is low); control pressure is being released
from the nozzle, and at a certain time t2, the control pressure falls
sufficiently low that the diaphragm ~alve snaps open (wave forrrl d going
high at time t2) and the nozzle pulse begins (wave form e going high3.
These conditions hole for the next 45 of rotation to time t3, at which
28 time spool ~; has rotated exhaust reces s 243b just past exhaust port 2Z9b,
~55-
~ZB65
236b in communication with the B supply recess Z31b. Hence, at tirne
t3 pre~sure is applied to the "b" side o the 6huttle val~re 187' ~hifting
the same to its l'a" side position. Thus, wave form b goes high as does
wa~e form c. This same ~5 rotation for spool A effects no change in
the e~hausting condition of spool A (and wa~e form a stays low). The
application of pressure by spool B to the ~huttle valve 187' i5 transmitted
to the control port of the nozzle and pressure begins to build up against
the noz~le diaphragm valve. At a certain time t4 the control pressure
overwhelms the no~zle pre6sure, and the diaphragm valve clcsee (wave
form d going low~. Closure of the diaphragm ~ral~re ceases the flow of
air into the nozzleS and the no&zle pulse begins to decay ~and wave form
e starts to go low).
After 90 of rotation, spool B remains in supply condition
(and wave fornl b continues high), and the shuttle valve and diaphragm
.
~ral~re are held as before (and wave form c remains high, while wave form
d rernains low); whereas spool A has ad~anced from exhaust to supply
cond~tlon (and wa-re form a goes nigh), which, however, has no effect on
the ~y~tem since spool B is already in supply condition. ~t 135 of
rotation, the system remains stable in all re~pects which continues for
another 90 of rotatio~ or until a total of 225 of rotation at which point
the supply port for spool B becomes blocked by the unrelieved portion
233b of the B supply recess which holds the existing pressure condition
on the shuttle ~al~re and diaphragm valve. Wa~e form b drops to its
interrnediate hold condition indicated in dotted lines in Fig. 7. Spool A
2$ r~main~ in supply condition during thi~ time and for an additional 4S
of rotation to a total of 270 of rotation, at which point spool A mo~res
- into hold condition (and wave form 2 drops tc) its intermediate dotted2g line position) while spool B remains in hold T)osi-lion. When the 315
-5~-
S
point is reached, spool B ha~ its exhaust port coinciding with its exhaust
recess and begins to exhaust (wave form b moving low). The pressure
being held in spool A (due to its hold condition) urges the shuttle valve
to its "b" side position (and wave form c goes low) which continues to
hold the control pressure against the diaphragm valve (and wave for~ d
remains low). The final 45 of rotation brings the system to the start-
ing point at ti~ne tl at which point spool A goes into exhaust condition and
a new cycle commences.
In practice, the extent the two spools would be adjusted out
of phase may differ from the 45 assumed above according to whatever
pulæe length may be desired and the frequency of the loorn cycle per unit
time. The pulse duration depends upon the length of time both spools are
in exhaust and can be varied by changing the relati~re times at which the
last 6pool goes low and the first spool goes high.
3~ Mechanical Embodiment Alternative Desi~n -~In the mechanically operating embodiment of Figs. 8 -
10, a shuttle valve must be interposed between the deli~ery ports of
the two spools in order to prevent a cro~s-connection between these
deli~rery ports which would allow a pressure condition applied by the
supply recess of one spool to vent directly to the atmosphere through the
e~haust recess of the other spool and ~esult in loss of control over the
working of the diaphragm valve. It is possible by modification of the
- design of the spool array to eliminate the presence of the shuttle val-~e
- and one design functioning in this way is illustrated in Figs. 11-13.
Except for the elimination of the shuttle valve 187', the housing and
driving means of the alternative embodiment are the same as in the
initial unit and for sake of clarity, in the diagrammatic perspecl ive view
28 of Fig. 11, the driving gears~ shafts and the like are omitted, and the
-57-
2~S
housing is shown only in outline by dotted lines as at 198', the various
air passageways which would in reality be formed aæ bores within the
housing being developed as independent conduits for sake of clarity.
Housing 198' encloses apertures 199'a, 199'b, in which the spools ZOl'a,
201'b fit. The spools thernse~res are identical, except that they have
opposite directions of rotation and have an opposite "hand". At the
opposite ends of each spool there are solid collar like sections 204a,
204b, and 206a, 206b which form a presæure holding fit when the spools
are mounted in the housing 198' and apart from several unrelie~red regions
or "islands", to be described, the spool periphery between these end
collars 204a, b, and 206a, b, 18 relieved or of reduced diarneter, as at
231'a, 231'b, to form a continuous annular chamber. A supply line 227'
~see Fig. 11) connected to a supply source of pressurized air (not shown)
branches to form ~upply ports 229'a, 22~'b so that the respectîve supply
chambers are continuously supplied with presaurized air.
At an intermediate point along the length of each spool the
annular upply recess is interrupted by an unrelieved full diameter
arcuate reglon of the spool periphery or island 242a, 242b, and an end
section of each such island has its mterior cut away as at 243'a, 243'b9
~o form an exhau6t recess which commuDicates through an axial vent
247'a, 247~b (see Fig. 12) with the interior bore 202'a, ZOZ'b, and thus
with the surrounding atrnosphere. A delivery port 235'a, 235'b i9
arranged at corr~sponding points on the periphery of the spool apertures
199'a, 199'b, and at an axial locatinn within the axial limit of island Z42a,
242b so that as each spool rotates, the assoclated delivery port can be
placed selectively into con~nunication with a supply recess, or with an
cxhaust recess ~in which case communlcatlon also with the supply recess
28 is prevented by the marginal edgcs c>f the island aro~md the exhaust
-58-
. , , , -: ,
,2~3~5
rece~s s~rving as a seal between the exhaust recess and supply recess3
or be blocked by an island itself. The two deli~rery ports 235'a, b,
connect to a co~non delivery conduit 236 which connects to the control
port of the no~zle ~ia conduit 189".
The rotary spools of the alternative design will likewise be
~ubjected to radial forces which would in time result in exce6siva wear,
and it is preferred in this embodiment also that s:ounterbalancing means
for ~uch radial forces be provided similar to thnse already described in
the initial embodiment. To this end, each island 242a, b, and exhaust
:
I0 recess 243a, b, is duplicated 180 out of phase by a pair of counter-
balancing islands 249'z9 249'b, and recesses 251'a, Z51'b, one pair
located to either side in the axial sense of the main island, and together
equalling the peripheral and axial dimensions of each main island and ex~
haust recessJ re~pecti~eiy. The recesses 2511a, 251'b are vented to the
atmosphere as at 252a, 252b. Each set of counterbalancing islands 249'aJ
b, and recesses 251'a, b, has an assoclated counterbalancing port 255'a,
255'b, which are connected to the same delivery conduit 189" a~ the
delivery ports 235'a, Z35'b. Thus, whatever pressure is applied to each
island or 0xhaust recess of each 8pool iS exactly counterbalanced ~y an
equal but opposite pressure applied to the counterbalancing islands and
reces6es .
The operation of the alternativ~e mechanical embodiment
closely resembles that of the main embodiment7 and a wave form diagram
illustrating the cyclic operation of the alternative form appears in Fig.
2S 13 (wave forms c and e being absent since the shuttle ~ral~e is omitted and
the nozzle pulse is unchanged). If both spools~ are in exhausting
condition (i> e. both wave forms a and b are low) or one spool is in ex-
28 hausting condition and the other suooi in hold or blocking conditio1-
-59-
.. . ..
86~
( i. e. either of wave forms a and b is low and the other is intermediate),
then the noæzle operating diaphragm ~alve will be open (wave form d
being high) and the nozzle will be meitting a pulse, Conversely, if both
spools are in supplying cond~tion (i. e. both wave forms a and b are high)
with their delivery ports communicating with a corresponding supply
recess, or if one spool is in supplying condition and the other in hold or
blodcing condition (i. e. either of wave forms a and b is high and the
other is intermediate), control pressure will be delivered through cont~ol
conduit 189" and applied against the diaphragm ~alve to close that valve
(wa~re form d being low) and terminates the nozzle diring pulse. Since
the relati~e positions of the exhaust recess and blocking islands are re-
versed in the two spools, the island leading in one spool, while the ex-
haust recess leads in the other spool9 one spool will be in blocking or
- hold condition while the other spool is in e~hausting condition and by
varying the angular relationship of the two spools, i. e., the arcuate dis-
tance represented by y in Fig. 13, the length of time that the diaphragm
i~ free of control pressure and thus the length of the no~zle pulse can be
adjusted. Ma~imum pulse duration occurs when spool A moves to hsld
position 6imultaneously as spool B mo~7es to exhaust pssition; wnile
minimum pulse duration occurs when both spools move simultaneously to
exhaust position. In Fig. 13 wave forms a and b have been drawn in
- positions representing the ma~imum relative separation of the two spools,
i, e, maximum pcs~ible length for y, the nozzle remainin~ open for a total
- of 90, for sake of clarity. In practice, the interval betweer. opening and
closing of the diap~iragm ~alve would normally be considerably sma]ler
and in any case, the arcuate extent of the islands and recesses can be
modiied to suit the circumstances.
28 f. Weft Meterin~ and Stor~e
- -60 -
~2~ 5
1) Preerred Rotating Drum E~nbodiment
An important aim of the invention i5, as already indicated, a
reduction in the amount of waste ir~volved in producing fabric in the system
of the invention. It it were attempted to control the length of the we~
~trand inserted into the warp directly through timed actuation of the weft
delivery clamp located upstream of the insertion nozzle, con~iderable
practical difficulties would be entailed. First, even electrically, i. e.,
~olenoid, actuated clamps designed for precision operation are not re-
producibly accurate within + 1 ms and given the high velocity of the strand
~10 under the impetus of the firing of the insertion nozzle, ~ariations in the
order of a few ms can easily result in significant differerlces in the length
of the delivered weft. For inst~nce, with weft arrival times in the order
of 30 ms, the weft is moving at an a rerage velocity of about 2"/ms so
that variation in clamp actuation time in the order of 3 ms would cause a
difference of 5-6" in the length of delivered weft.
Moreover, there is an inherent randomness in weft delivery at
the~elocities in question where the delivery is rom stored coils. For
example, as strand coils are whipped free from storage at high velocities,
they develop substantial inertial forces and consequently upon reaching a
limit~are subject to substantial overruning, i. e., backlàsh, the effect of
which is inherently variable, malcing it impossible to precisely fix the
length of strand advancing rom a coiled supply past a given point within
a fixed period of time. A180, the uncoiling strand develops a balloon in
its path from the supply and the drag resistance offered by the ambiert air
against this balloon is likewise variable and affects the instantaneous rate
of travel of the strand.
To avoid these practical difficulties, a different approach has
28 been ta~cen in the invention in the cc>ntrol o weft delivery, based upon two
-61-
8~5
~imple fundamental principles. First, since the duration of each operating
cycle of the loom i5 constant for a given operating speed, for instance 150
ms at 400 picks per minute loom operating speed, the exact length of weft
required per loom cycle is fixed, and the weft feeding de~rîce c~an be ad-
justed to exactly meter out from a supply package that exact amount of
weft during each operating cycle and deli~rer the saIne to a storage device.
With, for i~tance, a cylindrlcal feeder, its diameter is, of course,
lcnown, and sin~ple mathe~natics permits the calculation of the amount of
rotation per cycle required to deliver a length of weft equal to the loom
width. As the first principle, therefore, during each operating cycle of
the loom, there is delivered to a storage de~rice having a delivery point a
length of weft equal to that consurned during the cycle, i. e., equal to the
width of the loom.
Second, ;t is postulated that the collected weft strand be with-
drawn entirely from the storage device durmg each operating cycle and be
ætretched out as straig~t as pos~ible from the fixed delivery point
through the insertion nozzle into the shed, free of coils, loops, slack and
the like. If the examt amount of weft needed for each cycle is made avail-
able during each cycle, and i this amount of weft i8 actually withdrawn in
entirety from the storage device during each cycle, then obviously the
amount of withdrawn weft must be correct.
~n compliance with these principles, the systeTn of the in-
vention includes a weft ~netering and storage unit shown in detail at Figs.
14 and 15. This UIlit includes agenerally cylindTical drum 300 ha~ing a
polished peripheral surface and mounted upon the free end of a cantilever-
ed shaft 302 having a driven gear 304 that is positively coupled, as in-
dicated by broken line 306, to the dri~ing crankshaft C of the Ioorn to be
28 rotatably dr;ven continuously in synchr~ snth the loom crankshaft.
-62-
s
The coupling c~n take the form of driving and driven pulleys connected by
a timing belt, or alternatively of a variable speed transmission, ~o that
the extent of rotation of the drum per lc:om cycle can be adjusted and
thereby the linear distance of travel of a given point on the drurn peri-
phery per crankshaft revolution. The drum i9 disposed adjacent one side
of the loom with its axis of rotation extending generally parallel to the
axes of the lay and weft guidance tube (not shown in Figs. ~4 and 15). At
its inboard end facing toward the shed, the drum preferably has a conical
nose 308 to permit the strand to be withdrawn therefrom along its axis
without engaging a sharp edge.
The outboard section 310 of the drum aerves as a weft meter-
ing 1neans which functions to withdraw at a determined rate a correctly
metered length of weft from the weft supply package P, supported at a
convenient location on the loom frame, and to maintain positive frictional
engagement with the weft to thereby achie~te such controlled advance and
at the same time frictionally restrain the weft being deli~rered against
~lippage. The metering section oI the unit can take several forms but
preferably comprises a pinch roller 312 in pinchmg engagement with a
locus on the periphery of the outboard section of the drum. The quantity
of we~t that is allowed to be present on the outboard ~netering section of
the drum is not critical and can be varied ~ridely. Good results are
ac~i~ed in practice by applying two or more warps or coils of the weft
on this outboard section 310 in spaced apart, i. e, helical, relation, the
number of wraps and e~tent of the spacing, i~ e. ~ the pitch of the helix,-
2S being determined by se~reral spaced guide eyes or notches 314, the inner-most of which is ~ closed guide eye 316 positively engaging the strand
against axial withdrawal and con~tituting a fixed weft delivery point de-
28 limiting the metering section. Preferably, the pinch roller contacts
-63 _
... . .... . . .. ...... .
~2~65
sevelal wraps of the weft, assuring good control o~rer the weft during its
delivery to the storage section and avoiding possible snarl3, but other
ways of maintaining the weft under control in this region are available
and could be substituted.
Alternati<rely, if the weft is wound around the outboard section
310 of the drum in a number of wraps large enough to create sufficient
Erictional contact required for positive engagement of the weft by the drum,
pinch roller 312 could be eleiminated. However, the presence of the
pinch roller is preferred since it guarantees that the weft ad-~rances linear-
lQ ly with the drurn periphery and is not free to slip thereon. A~ a furtheralternative, a pair of eed rolls (not shown) engaging the weft in their nip
could be employed for controlled delivery of the weft to the closed guide
eye 316, but this would involve extra compl;cations in synchronizing the
rotational advance of such feed rollers with the drum rotation. ~ -
The inboard free end section 320 of drum 300 functions as a
weft 6torage means, serving to collect upon its surface the length of weft
wllich is delivered thereto by the metering section 310 by way of closed
weft guide 31b which i~ the transition between the two sections and estab-
lishes the outboard limit of storage section 320 of the drum as well as the
inboard limit of metering section 310
To insure that the coils formed by Inetering section 310 are
delivered by the closed weft guide 316 in proper sequence cn the storage
section 320, a sli~htly downwardly and inwardly inclined shoulder or ramp
3%2 is formed on the drum periphery in approximate axial aligrment with
the closed guide 316. As a coils is delivered to the storage section, it
contacts the ramp 322 and will be cammed inwardly thereby, leaving the
ramp clear to receive the next collected coil. Otherwise, a subsequent
28 coil might fall over or even inwardly of a previou~ coil and cause snarling.
-h~ _
~3Z~65
A preliminary guide 315 and tension 313 (see Fig. 15~ precedes the pinch
roller 312 to keep the wet from meandering laterally while advancing
from the supply package P.
Upon lea~ring the inboard end of the storage seetion 320 of
drum 300, the weft passes through a guide 324 arranged coaxially with
the drum axis, the guide preferably being in the for~n of a closed eye dis-
posed in the center of a vertically disposed plate 3Z6. During the with-
drawal of the weft coils from the storage section 320 during weft in-
~ertion9 a balloon develops as at 328 in the weft path upstream of this
guide eye, which defines the downstream li~it of the ballooIl, and the
plate 326 aids in preventing the balloon from overruning the rest of the
weft and creating tangles. Inboard of this balloon guide is a positively
actuated weft deli~rery clamp 330 which can in practice be located on the
lay just upstream of the insertion nozzle (not seen in Figs. 14 and 15)
At the operating 6peeds contemplated here, a fast response ciamp is a
requirement and, preferably, takes the form of a shoe 332 reciprocated
by means of a solenoid 334 into contact with a fixed anvil 336. The sol~-
noid 334 i8 actuated from the loom crankshaft as by :means of a Hall
effect switch~ cam operated microswitch or th~. like (not shown) adjuste~
to actuate a relay and close the clamp at the desired time, any lag in the
action of the solenoid being allowed fc>r in setting the timing of the opening
of the clamp which i6 not critical.
When the weft passes through the closed weft guide 316 into
proximity with the rotating surface of the storage drum section 320, an
air flow is created by the so-called Coanda effect which causes the weft
to follow the mo~ing drum surface. Howe~rer, the strength of the Coanda
effect is not sufficient to insure that aftcr the stored length of weft ha~
28 been withdrawn from storage section 3?0, an incoming fresh length of
-65-
, ~ . .... .. .... ... ..
weft will again wrap around the drum, and in order to apply an additional
wrapping force sllpplementing the Coanda effect, an additional circular air
flow i6 Ero~rided.
To generate this added flow, an annular ring 340 encircle
irl closely spaced relation the storage section of the drum, the ring being
hollow and generally toroidal in structure with itB hollow core 342 acting
as a manifold and connected to a SOUl ce of pressuIi~ed medium, not
~ho~7vn. This medium is for all practical purpo~es air, and hence the ring
will, for convenience be referred to as an air ring. The inner wall of
the air ring i~ perforated by a series of uniformly circumferentially
spaced slots 344 communicating ~vith the hollow core 342 and deli~ering
compressed medium therefrom into the annular gap 34b between the in- -
terior of the ring and exterior of drum storage ~ection 320. The slots
344 are inclined from ~he radial from their manifold end inwardly in the
lS direction of drum rotation, and a circular or vortical flow of air in-
dicated by dot-dash arrows 348 i6 thus generated around the storage
~ection of the drum urging the weft against the periphery of that section
to be collected in a coil and maintaining such coil tight to pre~rent slough-
ing. Moreover9 any slack that may develop in the weft due to relati~e
2G motion between the insertion nozzle and the fixed drum i6 automaticallr
taken up by the air ring flow and rewound upon the drum.
~n operation, the strand from the 9upply package is prelimin-
arily threaded manually through the preliminary guide, ~eneath the pinch
roller, around the metering ~ection the appropriate number of turns,
through the fixed wet guide (and any intervening additional guides), the
interior of the air ring, th balloon guide, the tens ion device, the deli~ery
clamp and finally through the injection nozzle. Then the loom can be
28 - operated in the usual way. Once the loom is in operation, the drum
-66-
J~ 5165
rotates conhnuously with air being supplied to the ring continuously and
after each length on the storage section i3 withdrawn therefrom during
weft in~:ertion, a new weft length is generated by the metering section and
delivered to the storage section.
The combined force of the air ring flow and the Coanda effect
can be varied and is sufficient to cause the weft to wrap upon the drunl
6urface whenever its tension falls below a certain level in the range of
about 1-5 gra~s, and this force is applied equally to the downstream as
well as the upstream side of the strand. That is, the biasing effect wîll
not only cause any freshly metered out strand tt~ wind on the drum surface,
it will equally cause any excess weft downstream of the- storage drum
section 320 to be wound on the drum surface which is useful in preventin(J
strand kinking. However, this effect can also pull the strand backward
and an important function of the weft delivery clamp 330 is to prevent the
weft from being pulled back out of She shed after its insertion and coin-
cidentally storage of weft for the next insertion is initiated. Obviously,
the tension developed in the weft by the firing of the insertion nozzle
greatly exceeds the biasing force of the air ring, but towards the end of
the insertion phase, there naturally comçs a time at which this tension
has been dissipated and the inertia of the inserted ~weft falls below the
biasing force of the air ring. I~ the weft ren~ained free when this time is
reached, it would be pulled c>ut of the shed as the biasing force of the air
ring takes over; hence the timing of the reacti~ation of the clamp rllust be
set to occur beore this point is reached.
Z5 Recalling that the pressure trace of the insertion nozzle firingpulse has a generally trapezoidal configuration~ one will understanc~ it is
necessary for the claInp to be activated to close not later than a few ms,
28 i. e., 2-5 rns, following the end of the firing pulse and preferably just
-67 -
~Z~5
slightly before the pulse ha~ completely dissipated. On the other hand,
actuation of the clarnp while the nozzle pressure remains at significant
levels is definitely to be avoided. If the weft i6 forceably restrained, by
the clamp or otherwise, while being highly stressed by the blast of the
insertion nozzle, then the weft tends to disintegrate because of the in-
tense vortical forces it receives.
The release of the weft by the clamp for the next insertion
step should likewise precede the activation of the insertion noz~le. As
regards the timing of the reactivation of the clamp relative to the end of
the insertion stage, when the stored weft coils are whipped free of the
~torage drum surface by the no~zle, the final coils tend to override the
drurn due to inertia as has already been mentioned, and it has been ob-
served that an initial rise occurs in the tension in the moving weft, as
detected by the tension detector 338, which is traceable to this backlash
effect. Therefore, the actuation of the clarnp should preferably be
delayed for a few, e. g., 2-5 ms, af ter the earliest tension increase to
allow this backlash efect to subside and the weft to assume its desired
6traightened out condition before being clamped. When the weft is drawn
straight back to the fixed weft guide, a decided peak appears in the weft
tension at the detector, and this indication can be used to establish the
correct timed relationship for clamp operation.
In determining the length of weft pro~rided by the storage drum
section, one must keep in mind that the drum is operating continuously
during the entire loom cycle so that an additional weft is being added to
the storage drum section during the very period that the already collected
weft lcngth is being withdrawn by the insertion nozzle. However, by
ollowing the two simple principles explained above, the delivery system
28 becomes fielf-regulating, in that with the correct amount of weft being
-6~-
,
$~ 36~
withdrawn in entirety back to the closed weft guide, it becc>mes im-
material how much of the weft length iB collected during the storage
phase and how much is added during the weft insertion stage. This
approach has the virtue of allowi~g a tolerance o a few ms ~vithout
difficulty due to the relatively 810w speed of travel of the weft during
metering and storage versus its high rate during insertion. For instance,
with a 48" loom and a 150 ms operating cycle time, the linear speed of the
weft while being metered and stored is only about 0. 3"/ms 60 that a
variation of + 4 ms creates a difference of only about 1" in weft length.
Because of the extremely fast advance of the weft upon with-
drawal from the storage section during no7zle firing, it may be desirable
to apply a retarding force beyond the light tension of the detector 338 to
the weft in the region between the balloon guide 324 and the delivery
clamp 330 and a conventional tensioning device can be employed to aug-
ment the detector tension for this purpose, However~ conventional
tensioning device6 are notoriously dif~icult~ to control precisely and are
better av~ided if possible. As an alternative, the advance of the weft
from the storage section 320 can be retarded by increaSiDg the separation
between the inboard end of drum 300 and the ballcon guide 324. This
correspondingly increases the size of the balloon 328 and thus the
resistance applied to the ballooning length of weft by the air and inertial
orces.
2) Alternative F xed Drum Embodiment
As an alternative to the rotating drum unit described above,
.
weft metering and storage can be carried out with a stationary drum unit
similar in principle to the strand feeder disclosed in ~TSP 3, 776, 480 to
which reference could be rnade for a more coInplete understanding. 1
2~ general, the alternative embodiTnent, as appears in Figs. 16 and 17,
-69-
~5'~65
includes a fixed support 360, which can be a bracket extending from the
loom frame, and in this support is double-journaled one end of a rotatable
shaft 362. A timing pulley 364 is affixed to the jhaft between its journals
for engagement by a timing belt 366 driven from the loom crar.kshaft (not
Reen) so as to create a positive mechanical drive between the crankshaft
and the rotatable shaft. The free end of the shaft projects toward the
loom in cantilevered fashion as at 368 inboard of support 360 to carry on
its projecting end a generally cylindrical hollo~ drum 370 via intervening
bearings 372 to per~it independent relative rotation therebetween. The
drum i8 formed of a plurality of segments 374 clamped between end walls
3769 377 in peripherally spaced apart relation to define a plurality, say
~ix or eight, of axial slots 380 (see Fig. 17) uniformly around the drum
~; periphery and a correspondlng plurality of a~ially extending bars 38Z fit
.
freely in these slots. The axial bars are each integrally connected at
about the~midpoint of their inner sides to a common supporting spider
384 fltting within the interior hollow drum but ree oi connection with the
drum segment6. The spider is journaled via a bearing 385 on a bushing
; 386 keyed as at 388 to the shaft end 368, the~periphery of the busning
~; ~ being both eccentric, as indicated at 390, and slightly skew6d or tilted
2 0 relative to the shaft axis, as indicated at 392, 60 as ts~ skew the axial bars
in their slots. The drum is held against rotation by one or more fixed
magnets 39~ each supported adjacent the drum periphery fr~m the end of
an arm 396 projecting from the fixed support and attracting an associated -
magent 398 recessed in one of the drum segments. Thus, when the
shaft rotates while the drum/bar composite remains statlonary9 the
spider 384 wobbles about shaft 368 imparting what is referred to as a
"nuta'cing" or "walking beam" motion to the array of axial bars 382
28 relal;ive to the drum periphery which serves to gradually advance coils
-70-
of a stland wra~pped a.ound the drum.
The outboard end of shaft 362 is hollow as at 397 to define an
axial weft pas~ageway for the weft ad~rancing from its fiupply package
(not seen in Figs. 10 and 17) and.communicates with the bore 399 of a
~5 radially and axially projecting hollow winding tube 400 having a free end
402 opening ~erminating adjacent the outboard end of the bar array 382.
For purposes of the present invention, an arm 404 extends frcm the end
of winding tube 400 to carry a closed weft guide eye 406 at a point along
the length of the clrum coinciding roughly with the midpoint of the axial
bars.
The inboard end wall 376 of the drum is surrounded by an air
ring 407 sirnilar in deslgn and operation to the air ring of the rotating
drum embodiment, and beyond the air ring, the end wall has a tapered
axial extension 408 to facilitate smooth passage of the weft thereby. A
balloon guide eye 410 similar to the balloon guide eye of the previous ern-
bodiment i6 arranged in spaced coaxial relation to the inboard end of the
drum to guide the weft to the nozzleO
The ~utboard ~xial section of the drum-bar composite between
the winding tube end 402 and the closed guide eye 406 funcetions in opera-
tion as the Ynetering section of the unit, receiving the weft delivered there-
to from the weft supply package via the winding tube 400, the winding tube
being rotated the correct number of turns per loom cycle in relation to
the diameter of the drum-bar coInposite ts~ wind UpOD the dru~n the desired
length of wet for that cycle. The inboard axial section of the drum be-
tween the closed wet guide eye 406 and the air ring 407 functions as the
~torage section for holding the length of weft which is withdrawn by the
insertion nozzle, the closed guide eye 406 forming the transition between
28 the metering and storage sections and limiti.ng axial unwinding of 1:he
-71-
.. . . . . .
6tored coils during ;nsertion. The weft guide eye 406 rotates bodily with
the windi~g tube and, in effect, progressi~ely transfers wraps or coils
of the weft previously applied to themetering séction onto the storage
~ection, while the winding tube lays down fresh wraps of weft upon the
metering section. The "nutating" motion of the bar array relative to the
drum periphery serves to space the coils about 1/16 - 3/3Z" apart de-
pendent upon the skew and to gradually advance the coils axially along
both the metering and ~torage section~ and maintain these coils in heli-
cally fieparated condition. The aggregate number o wraps of weft upon
the two sections is sufficient to exert enough frictional force upon the
weft in such coils as to hold the coils against 61ipping around the drum
following the rotating winding tube, and consequently, fresh weft is drawn
from the supply lnto and through the bore 399 of the winding~tube as the
latter ro,ates about the dru~n in t;med relatlon with the rotation oI the
crankshaft of the loom. Inasmuch as shaft 362 rotates at a considerable
rate, ~ e. g. several thousand rpm, in operation, careful balancing is
:: :
critical to vibration-free operation and weights 412, 414 can be provided
for counterbalancing purposes at approprlate pomts.
Air ring 407 functions in the same manner as before to re-
:
tain the weft coils on the storage séction of the drum and remove any
slack that may form between the injection nozzle and the closed weft
guide eye 406.
g. Weft Reception and Arri~al De_ection
.
In order to in~ure that the leading end of the weft after in
- 25 ~ertion through the shéd ifi engaged and contained during beat up of the
- weft, a hollow we~t reception vacuum tube generally designated V is
mounted on the end of the lay opposite the insertion nozzle, the tube being
28 open at one end located adjacent to and facing that side of the shed and
-72-
865
connected at its other end to z source of vacuum tnot shown) maintaining
a negative pressure in the tube of about 20" watcr. One preerred em-
bodiment of vacuum tube is 6hown in Fig. 18 and in this embodiment the
end of the tube adjacent the shed iB elongated or nattened as at 440 (see
also Figs. 2A and B) in a generally vertical direction parallel to the
plane of t~he reed R to concentrate the suction force. To reduce the possi-
bility of the leading weft end missing tnis slot~like opening having a width
of about 3/8", a laterally projecting flange 443, 444 extends from either
sid~ of thç opening to increase the "target area" of the opening. The
effect of these flanges is to momentarily half the movement of the weft
end if it should mis s the tube opening, which is enough for the suction in
the tube end to attract the weft end thexein.
It is advantageous for the arrival of the weft at the reception
tube to be positively detected. In the event~the weft end does not com-
pletely traverse the shed, which can occur when the weft end becomes en-
tangled upon itself, the result is a defect in the woven fabric which can
become permanent if weaving is continued. To this end, a photoelectric
detection unit can be provided at the reception side of the shed and is pre-
ferably associated with a modif~ed form of reception tube seen in Fig. 19.
I~ this embodiment, the tube itself is circular as at 440' and telescoped
over its open end is an enlarged collar 446 of generally oval or rectangulzr
~hape having a vertically elongated aperture 448 in its center communi-
cating with the suction tube and defining the weft entry 610t. The sides
442', 444' of the end face of the collar serve as the weft intercepting
flanges, and the edge around the inlet opening can usefully be beveled
or rounded as at 45(~ to further assjst entry of the t~eft end. Integrated
into the collar is a vertically spaced array of n~inute photoelectric beam
28 generators 452 and associated transducers 454 disposed along opposite
-73-
~;2~5
sides of the elongated entry slot at a plurality, say three, of vertically
spaced points. The response of such a multi-cell array i8 more reliable
than a single large cell, the minute cells being more sensiti~e to inter-
ception by a small thread while the multiplication of the cells increases
the lilcelihood of the weft being detected. As will be described more
fully in connection with the electrical circuit diagram of Fig. 21, the out-
puts of the photoelectric detection transducer are amplified and trans-
mitted through an appropriate circuit to a solenoid-operated clutch (not
shown) controlling the power transmis6ion from the loom motor to the
loom crankshaft to being the loom auto}natically to a halt in the event a
signal pulse from one or more cells indicating the arrival of the weft
fails to be recei~red within a set interval of the loom operating cycle.
That interval can vary but preferably begins when the shed opens to the
extent permitting weft insertion, i. e., at about 140 of the cycle, and
terminates at the front dead center position of the loom with the lay in its
full bbat up pusition, i. e., at 360. ~his interval can be established by
means of 6witches and activated from the loom crankshaft at the appro-
priate points c~f its rotation.
As is evident from the end ~riew of the reception vacuum tube
440, 440' seen in Fig. 21~, the axis of the rro, 440' during weft insertion
must be generally in registration with the axis of the interrupted weft
guidance tube T within the open shed S, which axis is necessarily spaced
forwardly of the plane of the ~eed R. Hence, if the reception tube remain-
ed Iixed in this position during beat up, its axis would lie forwardly of
the fell of the fabric (which coincides with the plane of the reed at front
- dead center) and since the free length of weft projecting outside the shed
i6 made as short as possible, say I to 1-1/2" so as to minimize the waste
28 resulting when such projecting lengths are eventually sheared from the
~74- ~
, , : .
fabric, and the fed weft ends could consequently be pulled out of the recep-
tion tube inlet as the lay approaches front dead center, this would result
in loss of engagement with the free weft end at the very moment such
end needs to be positively restrained for purpo~en of selvage formation.
Preferably, therefore, the reception tube is mounted for
linlited independent relative displacement upon the lay as appears in
Figs. 2A and 2B. To this end, a bracket 460 is affixed to the end of the
lay and upon this bracket ;s pi~roted a generally vertically arranged bell
crank leYer 462 carrying the suction tube 440 at its upper end. The lower
end 464 of the bell crank lever i5 linked to a collar 466 fixed to one of the
guide rods 55 forming part of the ~ertically displaceable support for the
interrupted weft guidance tube T. Thus, as the lay rocks rearwardly
and guide rods slide upwardly to introduce the wet guidance tube into
the opening shed preparatory to the weft in~;ertion, collar 466 also moves
upwardly to rock bell crank 462 forwardly and being the suction tube 440
into alignment with the guidance tube axis, Contrariwise, as the lay
~wings forward to beat up position and the weft guidance tube is withdrawn
downwardly below the shed, the bell crank 462 i8 rocked rearwardly to
displace the suction tube 2XiS rearwardly of the guidance tube axis and
into coincidence with the plane of the reed which l8 possible 6ince the
Buction tube is located outside the end of the reed. Any lateral offset
- betwe~an the location of the collar 466 and the bell crank 462 can be
bridged by extending one or more pvot shafts.
For some purposes, the engagement of the weft free end by-
2S the suction in the weft reception tube i6 desirably augmented by mean
o a positi~7ely acti~ating weft end clamp 470 (see Figs. 18, 2~ and 2B).
Such a clamp can be built into the rece~tion tube by cutting a slot in one
28 - side of the tube 440, as at 472, for the projection therein of a weft
. , .
-75-
86~
clamping pad 474 carried at the upper end of an upstanding finger 476.
Finger 476 iB pivotally nlounted at its lower end 478 to the bell crank 462
80 as to be Inov~ble bodily with the bell crank and the reception tube 440
carried thereby while also capable of limited independent pivotal move- -
5 ment. Below the pivot point the finger includes an angularly forward ex-
tension 480 whIch is adapted to engage an adjustable fixed stop 482 on the
lay when the bell crank 462 i5 in forward position (and the lay is in rear-
wa.rd pos~tion) during weft insertion, thereby swinging the clamping pad
474 out of the tube slot 472 and allowing the weft end to freely enter the
reception tube opening. Then, when the bell crank 462 pivots rearwardly
during beat up, finger 476 rocks with it which lifts extension 480 away
from the stop 482, allowing finger 476 to be biased forwardly by a spring
484 toward the reception tube eeat 472 to bring pad 474 into engagement
with the inside wall of the tube with the weft end gripped therebetween.
h. -Shed Weft Tensioning
After the weft has been insertecl entirely through the shed S
and its leading end engaged by the suction of reception tube ~T provided on
- the reception side of the shed, it may be desirable in some cases to apply
tension to the in-shed length of weft before it is beat up against the fell E
20 of the fabric. Unless the inserted weft is taut before its entwinement by
- the warp during shedding, any slack therein will be locked into the fabric
producing visible defects. If the insertion phase is carried out correctly,
the weft can usually be made to extend through the shed with adequatc
tightness, but if this problern does arise, it can be solved without the
25 necessity for physically engaging and stretching the projecting outside end
of the weft, vhich would undesirably increase the exteriorly projecting
- length of the weft thread and consequently increase the amount of waste
28 formed during producti~n.
_7~,_
~36~;
Effective in^3hed weft tension can be accompl;shed qllite
simply by employing the modified form of reception tube of Fig. 18 in-
cluding a positi~ely-active weft end clalnp 470, adding an adjustable
strand tensioning unit, which can be incorporated into the tension detector
338 in Fig. 14, in a position on the loom frame intermediate the balloon
guide and weft delivery clamp and altering the delivery clamp actuation
cycle to release the clamp prcsmptly after the free end of the weft strand
has arri~ed at the reception tube. The force applied by the adjustable
te~sioning device is adjusted to the level of the tension desired in the
weft length within the ~hed and i6 in any case greater than the force
applied to the stored weft coils in the wef~ storage section by the air ring
and the Coanda effect. Thus, the free end of the weft will be held by the
reception clamp 470 whick moves with the lay, while a part of the wet
upstream of the insertion nozzle N iB held by the teI~sion unit which is
stationary on the loom.
After weft insertion when the lay rocks a few degrees forward
from back dead center, the reception clamp 470 functions to engage the
weft leading end and thereafter continues to grip the Lree weft end after
the delivery clamp has been released. .As the lay moves towards front
dead center during the beat up phase, the di~tance between the insertion
nozzle and the stationary adjustable tension unit must increase (since the
hy~otenuse of a right triangle is always longer than its base side), and
this change in the intervening strand length is used to impart a straighten-
ing ten~ioniDg force to the inserted weft. The adjustable tensioning unit,
situated between the delivery drum and this length of strand i9, as
mentioned, adjusted to a level consistent with the tensioning force dcsired
to be applied to the inserted weft, Consequently, as the lay moves forward
28 with the rec cnd of the weft held ixed by the reception clamp, the
-77-
,. . .. ... . .. . . . .
adjustable tension unit grips and holds an opposite end sectio~ of the weft
until the tension along the entire length o the inserted weft exceeds the
Qet tensioning force. Thereafter, as corltinued movement of the lay
demands more weft, the adjustable tension unit yeilds to pass from the
storage section that arnount needed for the inserted weft length to move
bodily with the lay. In this manner9 the natural beat up motion of the
lay fierves to impart to the inserted weft the desired degree of tension so
that the weft is in proper taut configuration for beating up into the fell,
without resort to special slack-removing arrangements.
i. Fabric Selvage Formation
The fabr c produced by the weaving system of the inYention
must, like any other fabric, be adapted for further processing, such as
dyeing, printing, ~entering and the like, and must be able to withstand
the manipulation involyed in carrying out such operations. Thus, the
fabric must 'nave the capacity to be gripped along its edges and stretched
taut without unde~oing substantial unraveling. In normal weaving, where
the weft is looped back and orth across the shed without in$erruption,
there is formed a fabric edge of selvage which has the necessary re-
sistance "o v.~ithstand lateral tensioning since the end loops bend arvund
each ultimate warp end and effectively b;nd the same into the bo~ly of the
fabric. In the fabric of the present invention, however, the weft is in-
serted a1ways from the same side of the shed as discrete individual
lengths oî thread, the delivered weft being cut adjacent the sides of theshed, leaving its ree ends dangling loose along the edges of the warp. -
Obviously, since these loose weft ends can move freely in all dires:tic~ns,
~hey cannot withstand the tension inherellt in the sinuously-bent warp ends;
therefore, the outermost warp thread will be released and ree to un-
28 ra~el which releases the ne~t warp thread to unravcl and so on.
-7~-
. , . . : ,
~5Z1~65
This problem is particularly acute on the reception side of t!he fabric
because, in contrast to the delivery side where the projected length of
the ~illing strand is positively gripped within the delivery clamp pre-
ferably until sheared at the iEell line of the fabric, the free filling end on
the reception side of the warp has only light tension imposed thereon by
the vacu-~m reception tube which is not adequate to hold the warp threads
in place,
Several techniques ha~re been employed in the art to produce
a fabric selvage having the necessary integrity for subsequent mani-
pulation. In one case, tuckers have been utilized to engage each ex-
teriorly projecting ~eft end and to tucl~ the same bodily into the ne~t
created shed so as to form artificially a loop securing the outermost warp
threads in place. l~n another case, a group of two or more warp threads
are secured by means of a leno ehain stitch and an additional group of
æome 20-30 warp threads are provided to the outcide of the locus of the
}eno stitch to produce a so-called fal0e sel~rage. The weft is long enough
to weave with this additional group of warp threads, and the result is a
marginal strip suit~ble for engagement during handling. The weft endc
are loose on the outside of the false selvage which makes unrav~eling
2û possible, but this is inconsequential since after weft beat up is completed,
the false ~elvage strip is ~ev-ered froln the remainder of $he fabric and
di0 carded.
In either case, the result is the formation of a significant
amount of wasted thread. In the first instance, the tucking in of the pro-
Z5 jecting filling ends produces dense margins along the fabric edge which
are readily distinguishable from the body of the fabric and must be
severed and di0carded before the fabric is used; whik~ in the latter case,
28 it ifi the false selvage strip itself that constitutes ~vaste.
:
.,,:
-79
6S
Since the present weaving ~ystem emphasizes the reduction
to a virtual minimurn of the amount of waste resulting from its operation,
an irIlproved selvage forming technique has been devised as shown in
Fig. 36, and i~ preferably utilized. ln this technique, a leno chain stitch
is first formed in association with the outside three or four of the warp
threads, wh;ch are stippled in Fig. 36 on at least the reception ~ide of
the warp and for this purpose a conventional leno attachment of a
co~nercially available type is mounted on the front heddle of the loom as
indicated diagrammatically in Fig. 1 of the drawings. As i8 well known
in the art, a leno attachment takes the form of the two needle-like
members 490 arranged adjacent one corner of the front heddle H gener-
ally parallel to the plane of the heddle, each needle having an eye not
seen at its lower end through which a leno thread, shaded in Figo 36,
passes from a package (not shown) supported on the rear of the loom
frame ~Tia one of the guides 492 mounted on the heddle. The two leno
needles are mechanically coupled by means enclosed within a housing 494
in wuch a way as to undergo 180 bodily displacement in their relative
positions each time the front heddle moves to its raised position so as to
oscillate to and fro relative to the outermo~t three or four warp ends to
criss-cross the leno threads over those warp ends. When the front
heddle is in its upper position, the leno threads generally follow the
angle of the upper sid e of the shed forwardly of the heddle and then lie
above the ne~t weft. While when the front heddle is in lowered position,
the leno threads generally follow the lower side of the shed and then lie
beneath the next weft. In this way a kind of criss-crossing chain stitch
i~s formed around an outermost group of three or four of the regular
warp ends to bind them to the body of the fabric, as indicated by the
28 6haded leno threads in Fig. 36.
-80-
, . ,. :
~.t.~ 365
In operation, and as6urning, for instance, the use of two
heddle frames in the loom, the leno threads will wind beneath every other
weft thread and then criss-cross, i. e., switch their location, over the
top of each intervening alternatirg weft thread. If the number of heddle
S frames exceeds three or more, then the leno threads may criss-cross
QVer the top of one weft and pass beneath the remaining two or more wefts
before repeating.
The resultant leno chain stitch alone is not sufficient to bind
effectively the outermost warp threads to the body of the fabric. The
free weft end being, as already explained, completely free to move about
without restraint, the bight of each leno thread winding beneath a JUSt-
inserted weft will immediately pull free as ~soon as it is tensioned during
the next oscillation of the leno needles, destroying the chàin stitch effect.
To avoid th~s problem according to the invention, the;e is
associated with the leno stitch, a rotaTy binder stitch. To create the
rotary binder stitch, a carrier plate 496 for two binder threads G (cross-
hatched for identi~ication in Fig. 36) is mounted on the reception side of
She shed, and dupllcated on the delivery side as well if desired, at a
location on the loom frame on the warp beam or back side of the heddles
with the plane of the plate arranged ~rertically and it6 axis of rotation
ç-xtending generally parallel to the axis A of the lay. On the outboard
face of this plate is a pari of binder thread supply spools 498 and
threads G from these supplies are threaded through flexible strand
tension wires 500 projecting at diametrically opposite points on the plate.
An adjustable friction device (not shown) engages each spool to tension
the strand withdrawn therefrom. The flexible tension wires 500 extend
radially from the plate periphery to define bctween the guide eyes al
28 their respective ends a separation roughly equal to the stroke Or
' .
8 1 -
reciprocation of the heddles H and the binder threads G extend from the
terminal guide eyes to the fell F of the fabric.
The carrier plate 496 rotates continuously at a rate syn-
chroni3ed with the rate of operation of the loom so that the plate turns
~80 with each loom cycle and 5-10 in advance of or out of phase with
that cycle. Thus, the binder threads G move alternately up and down
similar to the shed forming movement of the warp threads but slightly out
of phase therewith, while being also simultaneously twisted about one
another at the rate of one-half turn of twist per loom operating cycle.
This twisting effect is in princlple the same as if the carrier plate axis
were parallel to the thread direction instead of perpendiculax thereto,
the only difference being that the rotation of the plate causes the binder
supply package 498 to shift bodily towards and away rom the fell E which
would introduce slack in the binde. threads G were it not fox the carrier
guide wires 500. These tension wires 500 are designed with sufficient
Ilex~bility to maintain the binder threads G under ten6ion during the
rotation of car~ier plate 496 so that the binder threads G remain taut at
all times throughout their length up to the fell of the fabric. The slightly
advanced timing of the carrier rotation results in the binder threads
crossing a freshly inserted weft as early as possible; and hence, the free
end of each weft is imrrlediately upon its insertion pinched between the
binder threads. In this way, each free weft end i9 caught iD the grip of
the twisted together binder threads G and held in place until the leno
chain stitch can be completed arDund that weft end~
Z5 it has been found that the combination of the leno chain stitch
and the twisted binder stitch imparts a ~high degree of integrity to the
fabric selvage and enables the same to readily withstand whatever stress-
Z8 es need to be imposed thereon during conventional fabric finishing
-BZ~
.. , . . - . -- : .
~5~6~
operations. While the projecting end~ of the weft are still nece6sarily
loose or free as a fringe, this does not result in the collapse of the
binder stitch because the twisted nature of that stitch acts to pinch the
free weft end between the opposed binder threads and hold it in place un-
til the wea~ing has progressed to the point that a sufficient number of new
weft ends ha~e been added as to pack all of the threads with ~ufficient
tightness or density as to hold them in place after releass of weaving
tension. For some purposes, the binder stitch alone may exert adequate
restraint upon the we ft ends 60 that the leno chain stitch can be dispensed
~vith, but it is preferred to employ the combination of these two stitcheæ
to achieve optimum results. In either case, it is unnecessary to remove
any pc~rtion of the margins of the fabric, as is required with a false
selvage or with a tucl~ed selvage, since the density of the fabric remains
uniform virtually to its e~ctreme edges and waste is, therefore, reduced
lS to a minimum.
j. Air Circuit
To aid in an understanding of the rnanner of ~peration of the
in~Tention, an "air" Cil cuit diagram or the pneumatic components is
6hown in schematlc fashion at Fig. 20. In this diagra~nJ air frorn a suit-
able originai pressure source (not shown) iB passed through a coarse
filter 51û to remove oil contamination and solid particles such as dust
and the like, above say 20~t in size, and then is delivered to a high
pres~ure line 512 and a low pressure line 512, the pressures in which are
determined by high pressure and low pressure regulators 516, 518,
I espect*ely.
High pressure line 512 has several branches, the first of
which 520 communicates directly with t}-e storage chamber 7S oI the in-
28 Bertion no~sle N or, more preferably as shown, with the air accumulator
-~3-
s
13? ~nd through that accumulator with the nozzle ~torat e chamber. A
second branch 522 pasæes through a solenoid operated ~ralve 524, movable
between a delivery and an exhaust position to a clutch (not shown) in the
dri~re of the weft metering and storage unit 90 as to disengage that clutch
and 3top further accumulation of weft on that unit when the solenoid valve
is activated during, for example, backing up of the loom to repair a
broken o- incomplete weft.
Another branch 526 passes through a fine filter 528 capable
of removing particles down to about 3 micron and then connects with the
inlet of the weft insertion nozzle control unit U (shown as the embodiment
of Figs. 8-10) for delivery under the control of that unit to the pilot con-
- trol inlet 117 of the insertion nozzle N itself. A fourth branch 530 passes
through a manually energized solenoid valve 538 having delivery and ex-
haust positions, and on to a feed port (which can be the same as pressure
tap port 181) in the supply passageway of the nozzle 50 as to allow bur~ts
of air to be emitted from the nozzle opening by direct operator actuation
of valve 538 independently of the nc zzle control unit U itself. The low
pressure line feeds continuously to the air ring 340 of the weft metering
and storage unit.
k. Electrical Circuit Diag_am
An elect~ical circuit diagram for the electrical components
of the air circuit diagra~n and other related components ~exclusive of the
electrical embodiment of control unit U) iB seen in Fig. 21.
As already mentioned, it is possible to operate the weft
delivery clamp by a spring-return solenoid energized by a microswitch
contacted by a rotary carn rotating with the loom crankshaft and con-
toured to open and close the seitch and thus the clamp at the proper times.
28 Obviously, however, it would be complicated to adjust these times with
such an arrangeInent. It is preferred, therefore, to operate the weft
delivery clamp with two separate oppositely driving solenoids which are
coupled together and to the clamp head and are energized alternately in
correctly timed relation. To this end, as shown at the bottom of Fig. ~1,
separate clamp opening and clamp closing switches 550 and 551 are each
connected on one s;de to a 12 volt D. C. line 549 and on the other side to
a different side of an integrated circuit flip-flop 552. Each of the out-
puts of the flip-nOp iB connected to the base of an associated power tran-
~istor 555, 556 is connected in series to one side of a corresponding
solenoid 557, 558 having its other side connected to the D. D. line 549 to
complete the circuit. When the clamp open switch 550 is closed, tran-
sistor 555 is activated to permit current to flow through solenoid 557 to
open the weft delivery clamp; while, conversely, when clamp closing
switch 551 is closed, transistor 556 i6 activated to allow current to flow
to the solenoid 558 to close the weft delivery clamp.
A preferred arrangement for operating switches 550, 551
appears in Fi gure 37 wherein switche~ 550, 551 take the form of Hall
effect switches mounted at radially 8eparated points on corresponding
arms 559, 560 pivoted on a shaft 561 rotating with the loom crankshaft.
Magnetic achlators 565, 565 are carried on ~eparate discs S62, 563,
~ixed to the shaft 561 for rotation therewith, at corresponding radially
separated points so that each of the actuators rotates in a circular path
coinciding with only one Hall effect switch.
As stated, close control, within 1 - 2 ms, of the actuation of
the weft delively clamp can be important, and the open interval of the
weft delivery- clamp must be adjustable. Gross adju~:tment of the relative
positions of magnetic actuators 564, 565 is possible by means of a
clampable pin and slot connection 566. In addition, fine adjustment is
-~5-
... ... .. .. . . . . ... . . . .. . . . . .
i5
achieved hy forming the ends of the arms 559, 560 as gear segments as
at 567, 568, for engagement with pinions 569, 570 fixed on the frame of
the loom and secured by spring-biased detents (not shown) in any rotation
position. The arms pivot independently on shaft 561 and by turning the
pinions 569, 570, the relative peripheral positions of the arms and thus
of the Hall effect switches themselves can be precisely adjusted.
A loom normally incorporates a so-called loom B'SOp ms)tion
connected between a 12 volt A. C. source and ground and including a
mercury switch 540 associated with the operating position tbeing shown
normally closed in :I?ig. 21). A drop wire switch 542 responsive to the
warp drop wires (not shown) to be closed when a warp thread breaks is
connected in parallel to a manual loom stop switch 5439 and bDth are in
series through switch 540 with the loom "stop" 601eno~d 544 controlling a
clutch (not shown~ tran~mitting power from the loom lnotor to the loom
crankshaft so as to autom~tically stop the loom when any warp strand
breaks during operation or manual stop swilch 543 is closed. This
circuit is conveniently used in the present invention for stopping the loom
ill the e~ent the photoelectric weft detector array in the reception tube
fails to detect ihe arrival of the leading weft end at the proper time. To
this end, the output of a triac of bi-directional thyristor 546 i6 also
connected in series with the stop solenoid 544 through the mercury switch
S40, be;ng in parallel with the drop wire switch 542 and the manual stop
~witch 543. The output of photodetector, emitter-transducer array 4S2,
454 (Fig. 1~) is amplified for practical reasons by an operatiorlal
amplifier 5~5 and applied to the S input of an E~S nlp-flop 537 having its
Q output open and its Qoutput connected to one side of an AND gate 534.
- A resetting pulse is derived from the clamp open switch 550 and aIter
28 being stretched in a pulse stretcher 531 is applied to the R input of
-~6^
flip_flop 547, the duration of the stretching extending until a few nls after
front dead center of the loom. A timing pulse derived from the clamp
close switch 551 is delivered to the other side of l~ND gate 534 after
being delayed as at 532 so that its arrival coincides exactly with front
dead center of the loom. The output of AND gate 534 is applied to the
trigger of triac 546.
Unless interrupted by the arrival of the weft, the photoelectric
array is continuou61y conducting and the S input of the flip-flop remains
at logic 1 which holds the Q output at lc>gic 1 and the Q output at logic 0.
Thus, If nc> weft has arrived by the time the loom reaches front dead
center, both inputs of the AND gate are at logic 1 and a pulse iæ passed
by that gate to trigger the triac aDd actuate the stop motion solenoid. If
a weft does arrive, a momentary logic 0 is received at input S which
acti~rates the flip-nop to make ~ go to logic 0 and Q go to logic l. Since
the pulse stretcher 531 holds input R at logic 1 until after front dead
center, the flip-flop holds Q at logic 0 irrespective of subsequent fluctua-
.. .:
tons of the R input between logic 1 and logic 0. Upon the termination of
-: t~e stretched reset pulse, input S returns to logic 0 which reaets the
lip-nop to make Q go to logic 1 and Q go to logic 0.
If the weff arri~al detection array should become disabled,
the loom is automatically stopped since aDy interruption in the photo-
electric output activates flip-flop 547. When the loom is operated to
`. correct the defect due to weft nonarr*al or other problen~s, mercury
- ~witch 540 will be opened to disconnect the stop solenoid and simultan-
eously reset triac 546.
A loom back-up switch 548 on the operating handle supplies
A. C. current to the weft eeder clutch solenoid ~alve 524 so as to dis
28 engage the weft feeder clutch and avoid entanglement or further
;'
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,, . . . , , . -- , . ... . . . . . . . . . .
365
accumulation of weft on the feeder while loom crankshaft is moved manu-
ally to make necessary repairs to fabric or loonn. Similarly, solenoid
538 which controls a valve for admitting feeding air directly into the in-
sertion no zle independently of the nozzle control unit U is connected to
the same power line on one side and on the other to a manually operated
s vitch 547 and thence to gound. The operator by closing switch 547 can
admit a pulse of air directly to the nozzle to project a weft during
initial threading up.
Conversion of Shuttle Looms
While the air weft insertion system of the invention can ad-
vantageously be embodied into a ~oom of new design, any entirely new
loom would require substantial, if not complete, redesign in order to
make ophmum use of the features of the invention and would entail a
large capital in~estment forthe in~ention to become available to the
texti~e industry. It has been found that the principles of the in~ention
are equally suited for the conversion of e~cisting shuttle looms with only
~elatively modest modifications which would permit the invention to be
used at far less c06t, and the details of what i~ invol~red in converting an
existing shuttle loom for the practice of the inYention will now be
described,
Since the pre~ent invention dispenses with the 3huttle, the con-
~entional picker motion and shuttle boxing motion can be completely eliln-
inated. While the lay is retained, the massive lay bealn ordinarily re-
quired in shuttle looms is unnecessary and ~mdesirable and can, accord:
ingly, be replaced by a skeleton lay consisting essentially of a light-
weight .hannel to support the ~veft guidance tube, insertion nozzle and
other related components. Since the diameter of the guidance tube is
28 significantly srnaller than the shed "en~elope" required for the shuttle~
.
-88-
.. . . . . . . . .
6~
he maximum separation of the shed can be reduced by at least about 30%,
e. g., from about 2. 4" of vertical separation for the shuttle loom to about
1. 7" in the loom of the invention) which makes possible several other
desirable alterations. First, the reduced shed opening means that the
arcuate path of the lay can be correspondingly shortened, i. e., by about
30%, specifically from bout 6" for a shuttle loom to 4. 5" or less for the
invention, which in itself allows the lay driving rate to be incrcased.
Secondly, the reduction in the maximum shed opening makes possible a
corresponding reduction in the vertical travel of the harness motion. In-
asmuch as the harness motion on existing shuttle loorns is an important
factor in limiting maximum operating speed, this change is especially ad-
vantageous. The fell line as well as the shed angle (i. e., the included
angle between the separated warps of the ~hed) remain unchanged here.
Howe~rer, the harness motion must be shifted forwardly from its usual
location relati~e to the lay, but this can be done with little difficulty parti-cularly as most existing loomB already provide for adjustment of the
harness position.
With these modifications, and ubtracting the added weight of
the special inventive components, the overall weight of the loom, and
particularly its reciprocating parts, can be reduced by several hundred
pounds; consequently, about 16-Z0% less power is required to dri~re the
loom of the in~ention, e. g., about 3/4 - 1 HP versus 1. 2 HP for a shuttle
loom. The ultimate result of all of these savings is a converted loom
capable of operation at 2-3 times the maximum speed of conventional
2~ slluttle looms at a cost of 10-20% of the cost of a completely redesigned new loom.
II. Operation of the System of the Invention
Z8 a. Introduction
_~9
6S
In the course of the preceding detailed description of the
apparatus of the system of the present invention, considerable informa-
tion has already been conveyed, either directly or indirectly, as to the
mode of operation that is followed in the practical utilization of this
apparatus. However, ce~tain process conditions are o peculiar import-
ance in the invention and need more detailed description aug~nented with
actual test results.
Some preliminary general comments might be helpful to an
understanding of the results of these tests which, basically, involve the
projection through the warp of a standard 48" loom of a proper length of
yarn drawn rom the weft metering and storage device described above
through a ~standard~ weft guidance tube utilizing a given combination of
~ozzle configuration and test conditions. For this purpose, a "standard"
guidance tube iB 48" in length, composed of 3'0 equally spaced annular
elements, one for roughly every 12 warp strands, each 1/8" in thickness
(i. e. axial dimension) and havi:ng a 3/4" diameter honed internal bore.
For each test, the supply chamber of the nozzle, and the accumulation
~eser~oir where present, are pressurized with air to a given "supply
pre6sure" by an uninterrupted connection to a pressure main of the same
pressure, and the actual values of the "supply pressure" are measured by
means of a pressure gauge (not shown) communicating with the interior of
the nozzle supply chamber~ A feed tube having an outside diameter of
0, 095" is arranged within each nozzle with its free end projecting approxi-
- mately 1/8'1 beyol~d l:he plane of the exit of the contoured section exclusive
of the extension barrel where present, and the weft to be projected is intro-
duced into the feed tube with its leading free end projecting a short distance,
e. g., approximately 1", exteriorly of 1;he feed tube end, and simulating
28 a practical weaving condition where the weft is cut between the no~zle and
-90-
.. . . .. . . . . .
~ ~5~2~6S
Abric edge.
AfSer the noz~le has been activated or "fired" with a sufficient
level of supply pressure, the weft length will be projected through the
nozzle and into the guidance tube. For a given noz~le arrangement and
~et of test conditions, the time required for the free end of the weft
length to traverse the entire length of the guidance tube and emerge from ~ ;
the far end thereof has been found So be reproducible with a reasonable
level of accuracy, and this time, referred to herein as the "weft arrival
time" i~ a useful characteristic in evaluating the effectiveness of the
particular test conditions. For consistent evaluation, a distance of 52"
has been fixed as a practical test distance the weft must travel for
measuring these weft arrival times, this distance including the guidance
`~ tube itself and sufficient clearance space at either end to approximate
what would be needed in actual practice on a 48" loom.
The technique used for measuring the "weft arrival times" is
as follows: A stroboscope is located at the fixed test distance from the
nozzle (outside the egress end of the guidance tube), the stroboscope being
activated by means of an ad~ustable interval timer, calibrated in micro-
seconds, which i6 started by the firing of the noz~le itself so that the
Z0 strobe fiashes after passage of whatever interval o time is set on ~thetimer following the instant of nozzle fising. The egress end of the tube is
then visually obser~ed by a human observer to see the locaffon of the
leading end of the weft when the stroboscope flashes. The test is repeated
with appropriate adjustments of the timer by trial and error until the
leading end of the weft can be seen just reaching the 52" test point at the
mornent of the flash. This technique is simple with a good degree of
reproducibility virtually free of human error and can easily be recorded
- 28 for subscquent confirmation with a camera viewing the test point. Once
.,, ., ... ~, .. ., .. , .. ".. , ., ,,.. ,.. ,, .. ,. ,~,, ,., .," .. ., ~, .. ................. . .. .
~2~6~
the timer reading matching the instant of arrival of the weft i8 formed, the
test i8 repeated once or more times to insure accuracy. When measured
in this fashion, weft arrival tinles accurate to 1 millisecond (ms) have
been obtained with reasonable consistency.
The firing of the nozzle ~fill deliver a burst of air into the
guidance tube and the emergence of this flow of air can be detected (and
actually felt by hand), and, here again, the time required for the air
current to tra~rerse the given fixed distance, namely 52" is generally re-
producible for a given set of conditions and has been found to pro ride an
ind;cation of the maximum theoretical efficiency that a given arrangement
is capable of achieving under a given set of conditions. The period of time
~or the air burst to pass tkrough the tube and reach the fixed end point is
referred to herein as "air arri~al time" and is preferably measured by
,
means of a hot wire anemometer situated at the fixed point and connected
to the recording oscilloscope measuring the lapse in time in milliseconds
between firing of the nozzle and TeSpOnSe of the anemometer, As is knou~
in the art, a hot wire anemometer changes in electrical resistance in re-
6ponse to fluctuations in it8 ambient temperature~ which resistance changes ~ -
can be detected by a recording oscilloscope. Since a change in the ~ elocity
.
ZO of air ambient to the hot wire produces a temperature fluctuation at the
wire, this device effçctively detects the instantaneous arrival of the air
flow at the fixed point.
As is well known from the principles of fluid flOw, the pressure
which is actually delivered to the throat of a nozzle is virtually never the
2~ aa~ne as the supply or line pressure since the pressure le~el which can
be "seen", i. e., recehred, by the nozzle throat will necessarily be
affected by the inherent resistance of impedance in the connections exist-
28 ing between the supply lines and the nozzle itself. The term "head
.
-92-
- ,. - , ,
~2~5
`pre6sure" or "stagn~tion pressure" is used in the art to di~erentiate
actual nozzle pressure from supply or line pressure, and this distinction
i8 followed her~. Specifically, the term "head pres6ure" or the equiva-
lent "Stagnation pressure" as employed in describing the ~arious tests
carried out here isS intended to mean the pressure measured by a strain
gauge pres~ure transducer mounted about the midpoint of the deli~rery
passage of the nozzle upstream of the throat, as indicated rousahly by the
dotted lines designated 114 in Figure 4, the signal from this transducer
being delivered to a recording oscllloscope. On the other hand, the terrn
~;10 "æupply pressure" is that pressure measured by a gauge connected to the
supply chamber which will be in equilibrium with the line pressure before
nozzle activation.
With these prelinlinary explanatory observations, the dis-
cussiosl will now address particular opesating conditions.
15~ b. Nozzle Pressure
It is of critical impo~rtance to the present invention that the
"head pressure" of the nozzle be sufficiently large to achie~re a "choking"
:~ :
~ ~ ~ c ondition at the throat of the nozzle itself and not upstream or downstream
~, :
of the nozzle throat. The term "choking" has been derived irom the fleld
of aeronautical testing, e. g., wind tunnel testing, and iB accepted to
m~an the deli~rery to the nozzle of air under sufficient pressure that the
velocity profile across or transversely of the air ~low passing through
the throat area uniformly equals sonic velocity, i. e., has a velocity of
Mach No. 1. O. Generally, it is known that a nozzle throat will be "choked"
in this senSe when the ratio of the head or stagnation pressure actually
available to the throat itself to ambient pressure i8 at least 1. 894/1.
Contrary to the experience of aerodynamic testing where choking is an
28 undesirable phenomenon, it is essential in the practice of the present
s~3_
,~ . . . .
~n~ention that a choking condition be produced directly in the nozzle throat
and not before or after that throat in order to maximize the thrusting
capability of the nozzle upon the strand disposed therein.
Thus, the throat of the nozzle of the present invention must
constitute the point at which maximum inpedance occurs within the delivery
connections between the pressure source and the nozzle throat, including
impedance due to turbulence of ~low as well as boundary layer pheno-lnena.
By the term "boundary layer phenomenon'i is meant the tendency of a
layer of fluid adjacent a stationary sllrface or bc~undary to be substantially
stationary and exert resistance to the flow of fluid along that surface, the
extent of such resistance increasing as the surface length increases. To
this end, the air supply components of the present invention al~e especially
designed to allow air to flow therethrough wlth minimum impedance losses
of all kinds, the distances between the pressure supply source, i. e., the
,
cupply chamber and accumulator and the no~,31e being as short as reason-
ably possible, and all connecting lines being o ufficientl~,r large size as
to eliminate significant impedance. Further, the delivery passagewaSrs
e~tending from the supply chamber to the throat are carefully contoured
for turbulent-free flow together with suificient circurn~erential dimension
as to substantially exceed, e. ~., by a factor of about S, the actual throat
cross-sectional area, notwithstanding roughly equal radial or annular
dimensions, bearing in mind that the annular throat area of the present
nozzle is reduced by the presence of the feed tube therein.
A.s already stated, the basic determinant of nozzle choking is
the existence of a pressure relationship between the nozzle head pressure
and the ambient atmosphere in the order of appro~imately 2:], and the
achievement of this ratio is the prime indicator of the occurrence of a
28 choking condition. However, additional indications of this condition are
-94-
.. . . . . .
S
provided by the quantitative relationship o~ the head pressure to the
fiupply pressure9 in that the head pressure for a choked nozzle will tend
to more closely approach the supply pressure and by the pressure
"history" for the nozzle obtained ~uring a cycle of operation. If the
pressure tran6ducer comxnunicatir1g with the nozzle delivery passage just
upstream of the nozzle throat is used to continuously record on an
oscilloscope the pres6ure at that point during an operating cycle, the
pattern of this recording gi~res a pressure trace of "pressure history"
which re~eals significant information about the nozzle, as will be explain-
ed.
Where the nozzle length is extended to project, e. g., by means
of a barrel, downstream of the throat region which can be advantageous for
certain purposes, care must be taken to insure that the length of such ex-
tension is not such as to superimpose upon the sy~tem a subsequent or
downstream "choking ~oint" that would defeat the critical requirement of
the inve~tion of choking directly at the throat. The boundary layer effect
in an extended cylindrical tube introduces an increasing resistance or
impedance according to the tube length, which is comparable in effect to
a physical restriction analogous to a thrvat, and this effect cannot be per-
mitted in this in~ention to develop to the extent of creating a "virtual
throat" smaller than and downstream of the actual throat.
In order to give a comparison between a variety of different
- nozzles for the purpose of tbe ~resent in~ention, extensive testing has
been carried out ~vith nozzles of different contours ar.d dimensions, and
the resultfi thereof appear hereinafter.
c. The Nozzle Contour
For purposes of this invention, the contour of the nozzle does
2R not appear to be critical and is subject to considerable ~7ariation. ~ arly
-9S-
,, , .. ~, .. , , ., , .~ .. . .. .. .. . ...... ....... .. . ... .. .
ln the research underlying this invention, the hypothesis was drawn that a
no7 ~le designed to produce supersonic air flow would be distinctly ad-
vantageous, if not crucial, to optimum high speed projection of weft strands
in a loom. Subsequent working data have disproved this hypothesis in that
while a noz~le designed for supersonic nOw i6 certainly ~uitable for the
practice of the invention, virtually the same operating efficiency can
surprisingly be attained by nozzles which are not designed for supersonic
nOw.
1) "Su ersonicall Contoured" Nozzle
p ~r .
The design of the noz~le contoured for supersonic flow has been
thoroughly explored in the aerodynamic field and requires no detailed e~-
planation here. Briefly, a so-called supersonic nozzle requires an outlet
opening located downstream of a converging throat, the ratio of cross-
sectlonal areas of the outlet opening re1ative to the throat being greater
than 1, with the interior nozzle wall in the region between the thro~t and
outlet being smoothly diverging in contour. With such a noz71e, the air
flow at the throat reaches sonic velocity and, if pressurized sufficiently,
upon entering the downstream divergent area will undergo an expansion
with consequential acceleration to above sonic speeds. The degree of ex-
pansion and consequential flow acceleration determines the maxi~num
~elocity capability of the nozzle, i. e., its e~ective Mach number, and
each nozzle must have its design parameters carefully selected in accord-
ance with its intended design Mach number capability when operated at a
given design pressure level. It is preferred that the divergent contouring
be ~uch as to produce flow expansion under carefully controlled conditions
to thereby preclude the possibility of so-called shock wave formation
caused by undesirable over expansion and subsequent collapse or re-
28 compression of the flow current to restore equilibrium. Also, the exit
~ .
-96-
., . , . , ., . . . . ~
pressure at the outlet opening should ideally speaking, exactly equal atnlos-
p~eric pressure for the same reason of avoiding shock wave formation.
Calculations e~tablishing the precise contours required for 6upersonic
nozzles over a range of Mach number capabilities have been e-rolved in
the aerodynamic art and additional practical information on this subject
can be found in the paper "The Design of Supersonic Nozzles" by A.
McCabe, the British Aeronautical Research Committee (BARC) Reports
and Memoranda, No. 3340, 1967, while a theoretical treatment appears in
the text ~erod namics of a Co ressible Fluid by Leipmann and Puckett,
Y m~ _
lQ John Wiley & Sons, New York, 1947, especially pages 30-37 and 218-232.
For present purposes, precise application of these calculations has not
been found essential and an approximation acceptable for the in~rention
can be obtained by simply establishing (e. g., with so-called "French
curve6"~ a smoothly curvPd divergent contour between the throat area and
the exit opening of the nozzle.
To demonstrate the behavior of ~upersonically contoured
nozzles, which for convenience are referred to here as "contoured
no~zles", a series of tests was carried out with a given contoured nozzle
alone and modified by the addition of extension barrels of varying length,
such barrels being uniformly cylindrical in ~hape ~,vith a diameter match-
ing the exit diameter of the nozzle and a length related to the nozzle exit
diameter by factors of 5, 10, and 20 respectively. The nozzle in this casa
was designed with a throat cross-sectional area of 11 m~n2, a throat
diameter of 0,175"~ and an exit diam~ter of 0.18b" to give a ~ach nu~nber
of approximately 1. 5 for a "design" stagnation pressure of 39. 3 psig. The
a~ial distance between the plane of the throat area and the plane of the
exit opcnin,, is 0.120", and the nozzle surface is smoothly contoured in
2R divergcnt fashion from the throat to the exit opening. The test results
- 9 1 -
,
~3'~65
for thcse nozzles operated at supply pressures ranging from 40 to 120
psig, in 10 psig increments, in terms of air arrival times, weft arrival
times as wcll as the effective head pressures attained appear in Table I
below, while the date from this table for weft and air arrival times versus
supply pre~ sure for all four nozzles is plotted in Figure 22, the respect-
ive nozzles belng designated according ~o the legend appearing on that
figure. The indication "NA" means "no arrival", i. e., the weft length
could not proiected across the 52" test length at the corresponding con-
dition
From the data of Table I several conclusion~ can be drawn.
The effect OD the air arrival tirres across this broad supply pressure
range of the addition of extension barrels to a contoured nozzle is nlinimal
- the curves representing air arrival times fc>r the four nozzles cluster
- closely together and are very likely within the range of e~perimentalerror. However, the addition of an extension barrel significantly improves
- weft arrival times for the particular contoured nozzle of this test when
,
operated at low supply pressures, this nozzle having poor efficiency at
such low pressures, the difference in barrel lengths having relatively
small significance. At higher operating pressureF~, on the other hand, the
unmodified contoured nozzle, i. e., without an extension barrel, operates
nearly as efficiently as the extended contoured nozzles. It will be seen
that the head pressure~ achieved by this group of nozzles come close to
the corresponding supply pressures; thus, essentially all of the energy of
the supply pressure was effectiYely delivered clirectly to the nozzle ~rvith
little measurable impedance indicating the occurrence of choking at the
nozzle throats irrespective of the absence or presence of an extension
barrel.
Z8 2) "Straight" Nozzle
-98 -
- :
865i
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h L~ o ~ `I ~1 0 ~
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. . .___ _ _ _ ___
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. _ . . . ___ ____ _ _
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_99_
'
8~
In addition to supersonically contoured nozzles, there have also
been tested for purposes of this invention nozzles which instead of being
contoured divergently downstream of the cc~vergent throat area, extend
cylindrically, i. e., with uniform diameter, to the plane of the exit open-
ing to the ambient at~nosphere. Such nozzles are referred to here as
"straight" to distinguish them from 6upersonically contoured nozzles and
when choked have only a maximum flow ~relocity at the nozzle throat of
Mach No. 1. 0, although upon leaving the exit opening, the air flow is
~ufficiently pressurized may expand into the atmosphere and hence may
reach supersonic velocity in a region adjacent the nozzle exit. The air
deliv~ery path for the straight nozzle is identical to that of the contoured
nozzles, (i. e., as shown in Figure 4j, the only change being the replace-
ment of an end insert section of the nozzle to give the different shape
and/or ~ize. Since a straight nozzle already incorporates a short ex-
tension barrel equal to about 5xD, extending~ downstrea~l of the throat,
comparative tests with additional extension barrels were not carried out
for straight nozzles, but instead tests were performed with straight
nozzles of varying throat area to illustrate the effect of increasing throat
area on nozzle performance, which effect would be expected to be sub-
stantially the same for both contoured and straight nozzles. The stPaight
nozzle6 tested included one of 11 mm2 cross-sectional throat area w}th a
throat exit diameter of 0.17S" (for direct colnparison with the unmodified
contoured nozzle of Table I) plus two others with throat cross-sectional
areas of 16 and 32 mm2 respectively, corresponding to throat exit dia-
meter~ o 0. 2015" and 0. 268". The same feed tube associated with the
contoured nozzle tcst was used here with its free end projecting just p~st
the exit plane o the nozzle and with the weft introduced with a 1" pro-
28 jecting length beyond the feed tu~e end as before.
., . ; . ,
s
:- ---~
r~ ~ ~ O~ O O ~ n oo
~ . ~ ~ .
QJ ~ _._. .
~ ~ ~ o~ 0 CO
uc~) ~1 ~
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0 ~ E~ Z ~ ~n t~ ~ oo es~ ~ ~
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S~ . ~ . ,
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h G ~ ~ ~ I r-~ ~
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~ I w ~ u~ ~r ~ o o o ~ ul
'~: ~ f~ ~ u~
Y~ S-l O_ ____ _ __ . _
H O . ~ S ~ ~ o ~ oo u~
. k u E~ ~1 Z cr~ ;1
k . ~ _ _ ._ _ . _
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0 .
~ ~ o C~ C: o o ~ o
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- I 0 1 -
.. . , ........ _, ., .,.,.. , .. .. .... -j-..... .
The results of the tests of these straight nozzles appear in
Table II aItd have been plotted in Figure 23, the several sized no~zles
being identified by captions. From these results, one concludes that air
arrival times as well as weft arrival times are generally improved, i. e~,
S lower, by ir~creasing the cross-sectional area of the nozzle throat. Here
again, the efficiency of the 11 mm2 nozzle, similar to the contoured
nozzle of Table I, is substantially better at higher than lower operating
pressures, and such behavior is seen to some extent for the 16 mm2
nozzle. That is, while all of the tested nozzles exhibit a potential or
1~ capacity for highly accelerated weft delivery times, as shown by their air
delivery times, that potential may in fact be realized only when their
driving pressure has been adjusted to a sufficiently high level since it is
at these higher pressures that the wet deliYeTy times exhibit a pattern
which begins to track or parallel the pattern o the air arrival times. For
this reason, it is preferred in actual practic~a that the Rupply pressure for
a given weft and no~zle be adjusted as nece~sary to produce weft arrival
times which change as a function of pressure at the same rate as the air
arrival times, i. e,, that the supply pre6sure be within the region where
the weft and air arriqal times are substantially parallel and optimum per-
~ormance is actually realized.
d. Nozzle Supply Capacity Variat ns
In all o~ the tests of Tables I and II above, the pressure source
for all nozzles tested included a supplemental supply reservoir or accumul-
ator designated 137 in Figure 1 ha~Ting a ~rolume of 80 in3 in addition to
the 6 in3 capacity of the nozzle supply chamber itself, this accumulator
being comtected to the nozzle s-tpply chamber inlet opening through a 3/8"
I. D. line of not more than 12" length and in turn connected to a line
28 pre~sure main having the indicated supply pressure. To illustrate the
- i~i2_
;~
, .
Aifference this added supply capacity makes on noz71e performance,
oscilloscopically deri~red heaf pressure traces were recorded using the
contoured nozzle of Table I having the 5xD barrel at a supply pressure of
100 p~ig with the aupplemental re~ervoir connected and disconnected,
respectively, and these head pressure traces are shown side by side in
Figures 3-~A and 34 B wherein each hori~ontal unit represents a time in-
teriral of S or lO ~ecs. and each vertical unit pressure change of 30 psig.
Both traces confirm the almost instantanec~us response tinle of the pre-
ferred noz;zle design of the in~ention, that is, the pressure rises from
zero to a maximurn near in both cases to the lO0 psig supply pressure in
less than 2 ms, and actually exceeds that pressure very briefly before the
pressure wave oscillations stabilize or dampen out after a few more milli-
seconds. It can be seen, however, that with only the nozzle supply
chamber cap~city itsel available, the head pres~ure after reaching maxi-
mum gradually decreases until at the end of the approximately 15 ~ns
nozzle activation period, the head pressure in the nozzle of the small
capacity (6 in3~ has dropped to approximately 70-75 psig. In contrast,
with the supply capacity augmented to a full B6 in3, as preferred, the
pressure trace e~hibits a virtual flat plateau maintaining full head pressure
over the entire activation interval of the nozzle and drops only after flow
of air to the nozzle has been positively terminated.
Data sh~3wing the effect of the difference in air supply capacity
on air and weft delivery capabilities of the nozzle is su~nmarized in Table
Ill below from ~,vhich one learns that the high capacity gi~es significantly
improved efficiency at lower pressures and slight improvement at higher
pressures. The data of Table III appears graph;cally in Figure 27 ~con-
solidated with curves illustrating the effect of another variable, i. e.,
28 the Mach number in contoured no~zles which will be discussed later).
. ~n.~;
,. . . . . .- . ~ . ;
~5~
Tab le I I I
. Ef~ect on ~eft ~rrival q~i~es ~ms)
o~ VAriation in SUPD1Y C~paci tv
A. Larv,e Car~acity (~6 in.3)
' Pressure 30 40 l 50 l 60 r70 1 80 ~ 90 100 110 l ]20 ¦
l _ _ . _,
i ~oz~1~ TY?C Mach Mo. __ _ l _ l _ _
, Con No Bb1 1.5 68 63 59 50 39 ¦ 35 35 33 28 25
~: ! B. Sma11 Ca ?aci~v_6_in.3~ l .
Con SxD Bbl ¦ 1.5 ~ 75 75 52 38 l 32 28 28 28 Z6
~10 ln the pressure traces for both the small and large capacity
nozzles, after completion of the "rise time", the supply pressure remains
well above ambient pressure over the entire pulse interval, and a distinct
inflexion or break appears in each trace on]Ly when the control valve is
~ ~ positively moved to closed position to cut o!Ef the air flow, the he d
pres~ure then decreasmg fairly rapidly to ambient. This behavior in-
dicates ~that the supply capacity volume, even when only 6 in3, is very sub-
stantially in excess of the rate of flow that can pass through the no zle
throat at the given pressure over the pulse interval and that the supply
capability of the supply chamber is in fact delivered to the nozzle throat
at a rate greater than the nozzle flow rate.
The "fall time: of each pre6sure trace tends to be somewhat
- longer than the "rise time" due to the need of residual air in the delivery
passages between the nozzle diaphragm valve and throat to dissipate but
the bullc o the pressure drop occurs almost instantaneously and the re-
mainder has no perceived effect on nozzle performance. As previously
stated, any clamping of the weft must occur only after substantial decay of
the trace to avoid disintegration of the weft.
28 e. ~ir Pulsc Width ~ariation
- .: O ~'
The results comparing high and low air supply capacities were,
a~ stated, obtained with an approximate 15 ms nozzle activation intervalr
as were the results of Tables I and II, and the option exists of altering
this interval to change the duration of the air pulse em;tted by the nozzle.
The effect of such alteration for both large and small capacity nozzles is
set forth in Table IV for the 11 mnl2 area contoured nozzle of Table I
supplied with a pressure of 80 psig.
T:~bl ~ IV
E~fect of VaxiatiGtl in Ai; Pulse.';~ ,h
. ~
. Pulse ~ dth (ms~ ¦ :
. 5 8 1 10 ! 15 ! 20 1 25 ! 30 1 35 1 ~~
A. Large CaT~acit v . .
:~ Air Arri~al (ms) NA 2~ 25 23 23 23 23 23 2~ ¦
Weft Arrival (ms) NA NA 55 33 ~28) ~8 26 26 25 2~ 1 :
Integrated
lS Pressu~e Units _ ~ .. 1179 _ _ ~ ~ -
B. Sr~1all Ca~aci ,~ .
~Weft Arrival (ms) I - _ 39 31 29. 30 _
Inteqrated j . I J
Pressure Units j - _ _ 9~ 1102 14~3 1560 ¦ -
.
2~; Below the lO ms level, the nozzle~ was incapable of pro~ecting the yarn
acro s the full 52" distance at all, as indicated by the letters "~" (no
arrival, but significant improvement was obtained with this nozzle at
higher operating pressures, as was true in Table I and Fig. 2Z. ~ the
test utilizing only a small capacity t6 in3) unit, only weft arrival times
were recorded at several pulse width inter~als.
Based on this data, for the nozzles in questionr the air p~llse
width or duration should be at least about 10 ms and preferably within the
28 range of about 15 - 35 ms at the preferred pressure range of about 60~80
- 105-
p6ig, dependent upon air supply capacity and other considerations~
To provide an alternative basis of evaluation, the areas under
the pressure traces for the pulse obtained with the small capacity (6 in )
air ~upply plus one large capacity pulse for comparison were integrated
to give a value representing the total q-aantity of "pressure units" ex
pended during the entire air pulse, and these values are stated in Table
IV as "integrated pressure units". The weft arrival time for the large
capacity nozzle varied somewhat from an earlier value, the latter being
indicated in parentheses. It will be seen from these values that the large
~upply capacity (86 in3) nozzle can achieve roughly equal arrival times as
a small capacity nozzle consuming about 30-40% more pressure energy,
as measured in integrated pressure units.
f. Comparati~e Prior Art Simulation
To afford a basis for evaluating performance of the system of
the invention against the periormance typically achieved by prior art air
weft insertion systems, a simulation of a typical prior art system was
-~ devised as shown schematically in Figure 24. To eliminate the influence
. on performance of no~le design, the nozzle of the ~imulation was actually
a version of the noz~le of the invention, as depicted in ~igure 4, with the
actuating diaphragnl removed and the 6 in3 supply capacity volu~ne
blocked out with an impermeable filler, e. g., wax, so that air admitted
to the end opening of the nozzle fed directly into the annular pa~sage 115
in the nozzle head aIId thence to the delivery passageway of the no~:~le.
The nozzle inlet was connected by three feet of an air condui$ of 3/8" O. D.
and about 1/4" I. D. to the outlet of a 1/4" cam operated poppet diaphragm
valve. The inlet side of this valve was in turn connected by l~" oI the
same tubing to a pressure regulated capacitor. The poppet valve was
28 actuated by means of an air motor rotated at approximately 400 rpm7 the
- 1 06 -
, ., . ., , .. ,, ., ., . ", .. , , .. , .. ., .. , .. .. ,,, . ~, .. . . . , . " , . .. . . .
865
configuration of the cam being ~uch that the poppet valve was displaced to
open position for an interval of 55-60 msO
In order to allow the air motor driven poppet control valve to
be brought up to operating speed before delivery of the air thereto, the
5 air supply capacitor actually took the form of ~ne of the nozzles of the in-
~e~tion including the supplemental reservoir (total capacity 86"3), the
outlet of the nozzle being connected to the inlet of the poppet ~alve as
stated. ~n this way, instantaneous delivery of the air to the already work-
ing poppet val~e could be readily accomplished, the supply nozzle valve
10 being maintained in open position throughout the full operating interval of
the poppet valve. The pressure deli~ered by this supply nozzle was ad-
justed to provide lhe desired effective supply pressure to the poppet valve.
All other conditions were the same as in the tests of Tables I and II, and
air arrival times, weft arrival times~ as well as pressure traces, were
derived and recorded as before.
The nozzles employed in the prior art simulal:ion were the
straight nozzles of Table II, ha~ing the same vary~g areas of 11, 16, and
32 mm2, respecti~ely, without any additional extension barrel. The
duration of the air pulse was 55-60 ms. The results of these tests are
summarized in Table V below and are ~lotted graphically in Figures 25
and 26 which plot air and weft arrival times versus supply pressure and
nozzle head or stagnation pressure, respectively. _~
/
~.
28 ~
2l~6S
_ _ ~ ..
,1 ~ r~l o ~ D o In o ~ r~J
a)u~ ~ ~
~ _ _ __ _
fS 5-~ rJ o t~ r o o
O ul ~,~ ~ ~ ~ ~ ~ ~r m ~ r~
,~: 11 rJ
E~ P( ~ --~
b~ ~ .c~ ~. ~ <~ o . ~ ~ o ~ ~ o
r~ rJ E~ ~ r~ r . Ln ~
~ _ _~. ___ ~ _ , .
~ _~ . .
In ~ ~ C~ Ll~ O IS') ~1 0 CO
6) ~ _ ~ Ln 11~ ~
t~ ~ r~ ~ _ _ ..
s.~ u~ ~ o ~ o o co' ~ Ln ~r
r~ Ln n ~ 7
~1S-J ~ 5C J-- _
l~ ..~ .~J r~ ~_1 ~ J t~ ~ O CO ~ ~n
,_ ~_J Ln ~n ~ ~r ~r ~ ~ r~
~ ~ _ _ . . . _ .
C~ _~ ;~ ~ r~ r~ o ~ Ln ~ c
rl ~ ~ r~l ~ ~:r ~ ~ ~ ~ ~ ~ N
~ r~ 0~ ~D O t~ r~ O ~cn CO .
~J~ ~--I ~ r~
~¢h rJ _ .
,_ ,~ t~ ~ o ~ ~ ~ N ~ O
O_ _ 1~ . ~ r~
O _ ~, . ~':
-~1UJ~ .
~ h
C~ o C~ ~ o o o C~
~ ~r Ln ~ o r;l ~
~ _ .
- 1 08 -
.... .. .. .. ..... ..... ..
From this data, one learns that the air arrival values for the
prior art simulation are substantially independent of variations in the
throat area (apart from the 32 mm2 area no~zle at pressures below about
50 psig, which gave even worse values) but in all cases are substantially
slower than the air arrival times achieved by the invention. ~asmuch as
the air arrival times constitutes a limiting factor on performance, in the
6ense that the weft arrival times can never exceed the air arrival times
so that the most one can hope for i8 to achieve weft arrival times as close
as possible but always somewhat less than the air arrival times, it follows
that the weft arrival times achieved in the prior art simulation are in-
herently inferior to those possible with the system of the invention and
are never in fact as short as the desired goal of 30 ms, even with a large
area nozzle and very high supply pressures. At low supply pressures, the
weft arrival times achieved with the small area nozzles in the prior art
Rystem may sometimes be shorter than those achieved with cornparable
nozzles in the system of the invention, but this apparent advantage is more
than offset by the greater duration of the pulse intervai in the prior art
. ~irnulation exceeding by four times the pulse interval o the invention
system, with a consequential greatly multiplied consurnption of air. Thus,
compared on the basis of actual energy consumed, the system of the in-
vention exhibits significantly greater overail efficiency. In addilion, the
sy~tem of the invention has the potential for greatly improved efIiciency
by increasing supply pressure which is inherently lacking in the systerns
operated in the malmer of the prior art.
2S The "pressure signatures" recorded for the various tests in
the prior art simulatioll are duplicated in Figs. 31A-I, 32A-I, and 33A-I
for 11 mrn2, 16 rnm, and 32 mrn throat areas respectively, covering at
28 10 psi intervals thc entire supply pressure range of 40-120 psig and
- 109-
. , . , . ,. .. . . ~ . ........... .. ... .. .
6~i
comparable "pressure signatures" for the ~ame 11 mmZ, 16 mm2, and
32 mm area noz;zles operated according to the invention in the tests of
Table II appear (with scale changes fo~ canvience as indicated) in Figs.
28A~I, 29A-I, and 30~-I, respectively, at the same pressures. Analysis
of these pressure signatur~s shows that for the invention, the instantane-
OU8 achievement of maximum nozzle pressure occurs essentially in-
dependently of supply pressure, i. e., is virtually identical throughout the
entire pressure range, and i6 only moderately affected by increase6 in
nozzle throat area. Even for a large throat area nozzle, i. e., 32 mm2,
the time for the head pressure to rise from zero to maximum9 i. e.,
"rise time", rarely exceeds ~ me, in a majority of instances is not more
than about 3 ms, and frequently is only 1 ms. Similarly, the "plateau
effect" discussed previously, wherein the maximum head pressure per-
siets substantially at full maximum level throughout the entire interval of
the pulse, is characteristic of all of the pressure traces representing the
invenhve system. Even for the maximum throat area nozzle, the loss in
pressure from begi~ning to end of the pulse is in the order of approximate-
ly 5% and never goes as high as 10%. The maximum pressure trace levels
representing operating head pressures f~r the invention closely approxi-
mate the supply pre~sure levels. From these relationships, one con-
cludes that the nozzles of the invention are thus delivering pressure energy
to the yarn at the highest possible eIficiency and are in choked condition.
Furthermore, the portion of the pulse in the invention during
which the mas~imum pressure is at least substantially maintained always
2S substantially exceeds, i. e., by a factor of at least two, the rise time.This means that the pulse is predominantly devoted to useful work with
m;nimum loss in "starting up".
28 - In contrast, the head pressure trac0s obtained during thc prior
110-
art simulation exhibit radically different characteristics. In the first
place, the "rise time" even for the very small throat area nozzles is in
all instances at least, and u8ually greater than, 20-25 ms and does not
becorne substantially shorter with increasing or decreasing n~z ~le throat
area. That is to say, the slow rise time of the prior art simulation is in-
herent i~ the air ~upply thereof and is not improved by varying the nozzle
area. Collaterally with the prolonged rise time, the pressure wave form
of the prior art system does not, after its initial pea~, show a temporary
o~cillation or "hunting" which tends to denote a fully loaded choked con-
1 dition.
In the second place, e~ren though each no~le in the prior art
~imulation maintains maximum head pressure for a significant proportion
of the pulse interval and until the poppet valve begins to close upon release
of its operating cam, thereby indicating an ample supply capacity of air
duri~g the si~nulation, the actual head or stagnation pres~ure level occurr-
ing within each of the nozzles during the prior art simulation is at rnost in
the order of about 60-70% of the supply pressure levels and is significant-
ly less than the percentages achieved in the invention. Moreover, the
difference between head and supply pressures increases dramatically wit
increasing throat area 90 that for nozzles with the largest throat area,
na~imum head pressure is in the order of only 25-30flo of supply pressure.
From these characteristics, one must conclude that the no7zles hl the
prior art silnulation are in no case choked in the sense of the invention,
notwithstanding their operation at supply pressures over the same range.
In the simulation pulses, almost as much, and sometimes
more, time is consumed in reaching working pressures, i. e,, "~tarting
up~l, as in maintaining working pressure which imposes a definite obstacle
28 to high opcrating speeds and efficiency.
g Other Variable Conditions in th~3 Invention
I) Air Velocit~L
Since the practically equivalent performance of super-
sonically contoured and straight nozzles in the system of the in-rention was
une~pected, tests were carried out to check this performance by measur-
ing the actual ~relocities of air pulses at the ~moment of entry into the inlet
opening of the guidance tube at speeds above and below sonic velocity
(i. e., M~ch l and observing the effect of such variation on air ar~ival
times o~er the 52" fixed test distance, as well as ~n the v~3locities of the
lû air flow measured at the tube exit. This was done by adjusting the dis-
tance between the noz~le exit plane and the tube entrance plane to achieve
supersonic and eubsonic air velocities at the guidance tube inlet, as
measured by a not wire anemometer located in the inlet and calibrated as
precisely as possible to accurately indicate air velocity, the~exit velo-
cities al80 being measu~ed by hot wire anemometer. The lesults of th~se ~ ;~
tests are shown in Table VI below a~d establish that the air arrival times
are virtually identical Irrespective of whether the init al air velocity was
cupersonic or subsollic, although the air exit velocities did reflect (but
not proportionatelyl the difference in ~t~rting velocities. This performanc~
~0 held true at head pres6ures of 60, 80, and 104 p8ig.
rrclble VI
. I
Ef~ect o Vt~ryi.ng Ai.r Velo~ ~.~l Contoure(l Nozzle
D1stalicc A1r.r Veloci1:y 1 .~.ir Velocity, I
Head sc3tween No~zle (ft~sec) t~t./sec) I ~ir .7~r.r-val;
Pressure _and Tllbe Tuhe ~ t. anceTub~ ~.Y;.t _ T~c (~
Z5 60 1.125 1200 1225 2~ !
2 . 500 900 ~ 28
1 . 125 1300 300 26
2 . 500 90~ 250 26
10'', 2.000 1300 375 22
28 4.250 900 ' 300 23
, ., i ~, _
.. , , . , . ~ . .... .. . .. . . .
~5~il65
2) Spacing Between Nozzle and Guidance Tube
As the preceding discussioII suggest6, an available option is
the adjustment of the clear nce space or separation betwen the exit plane
of the nozzle and the entrance plane of the guidance tube and a ~eries o
tests to establish the effect of nozzle spacing was carried out using a
supersonically contoured nozzle haYing a thrsat area of 11 rr~n2 and a
Mach number of 1. 5 with and without extension barrels of 5 times and 10
times the nozzle exit diameter, respecti~rely, ~t a supply pre6sure of 80
psig~ a pulse width of 15 ms and a large capacity (86"3) air æupply. The
air arrival times achieved when thiæ spacing waR gradually varied from
zero to 6" are summarized in Table VII. ~7
1 5 : /
~ ':
Z5
~/, ' ' ' ~
2 ~
.. . . . .. ... . . . . . . .. . . . .. .
~2136~i
¦ T~blo VII ' ¦
E~fect of Varyin~ Sp~ci.ny of Nozzlc
Exit from Guidance Tube ~n~r~ncl~ Wi~h and Without
Ext~nsi~n ~arrel
~,ir ~riv~l Timc (~s) ~
_ _ . __
Spacing in In:ch~s _ No B~rrel _ 5~p Barr~l lO~D P,2rr~1
0 .~ '~A.~ NA 27
'~ .250 : NA 25 26
.500 ~A 25 : 26
: .750 ~ NA 25 26
1.00~0 'I ~ N~ 24 . ~ 2;6:
; .250 : ~25~ 24 2~
: : ~ .S00 25 ~4 27
.750 27~ ~23 24
: ~: 2.:000 : 27 : 24 : 25
: .250~ ~ 28;~ ~ ; 23 24
.500 ~ I 28 ~ 2~ ~
- ~750; ! ~29~ : ~ 24 25
3.000 1 30 ~~23 ~ !~ 24
: ~ ! 32 ~ 2~ : I 25
: :~,500 ~ i 32 25 i 27
750~ 35 25 ~ 27
`: ~.~00 ', : 37 ~ 26~ 27
.~ : .250 ~ 1 37 : ~ 27. I28
: .500 I 39 :: 28 127
.750 40 28 12~
~",000 , 45 ~9 130
,2~0 46 30 I31
. .500 5~ 31 i32
.750. 58 32 j34
. 6.000 ~5 1' 3~ 135
,;' ' .
,,
114-
From these results, it follows that no real optimum location for the nozzle
appears to exi~t and variation in nozzle position within reasonable limit
has no significant effect on the air arrival times. Thus, between appro~
mately an inch or less up to approximately 3-4", ~atisfactory air arrival
times are produced and can be impro~red even further by the addition of a
~hort extension barrel to the nozzle. Beyond about 4" separation, the ai-r
arrival times begin to suffer even with the addition of the extension barrels.
3) Nozzle Mach No~
Another factor ~usceptible to change in the practice of this in-
lû ~rention is the Mach number of the super60nically contoured nozzle and to
explore the influence of this variable on weft delivery efficiency, a series
of tests was performed using supersonically eontoured noz:zles having an
identical throat area of 11 mm with increasing exit opening diameters
(i. e., 0. 186", 0. 207" and 0. 220") as necessary to provide design Mach
numbers of 1. 5, 1. 91, and 2. 07, respectively. These nozzle were tested
for weft arriv~al times only both with and without a 5xD barrel at supply
pressures in the range of 30-120 psig, and the data produced in the tests
are ~ummarized in Table VIII and are plotted in Figure 27. From this
data one sees that change in Mach number has little or no practical in-
fluence on the effectiveness of the nozzle in propelling the weft, although
the addition of a barrel does afford some improvement at lower supply
pressures. ~
.
2 8
s
Table VIlI
Effect on Weft Arrival Times (ms) :~
of Variation in Contoured : :
_Nozzle Mach Number
. .
: Weft Arrival Time (ms) . -:~
~ __ . __ __
Pressure 30 40 50 60 70 80 90 100 llO 120
. . ._ . .. _ _ _ _ _. _
Nozzle Type Mach N : ~ :
. ~ _ . . _ ~ _ _ .. ...
~: Con No Bbl 1.5 68 63 59 50 39 35 35 33 28 25
~; Con No Bbl 1.91 NA 70 62 54 36 35 33 31 31 27
:~ Con No Bbl 2.09 NA NA 72 45 40 34 33 31 29 29
Con 5xD Bbl 1.5 68 58 39 33 30 30 30 28 26 24 . :
Con 5xD Bbl 1.91 NA NA 53 41 30 25 26 26 24 21
Con 5xD Bbl 2.09 NA 64 43 35 33 33 29 24 23 21 ;
~15 All of the tests in Table VIII included the large (86" )
supply capacity for the various nozzles, and it will be recalled . -~
.
that Figure 27 includes a curve representing a test of a Mach
1.5 nozzle with a SxD barrel identical to the corresponding
nozzle of Table VIII, but having a small capacity (6"3) air
supply. Comparing these results, one sees the considerable
: ~ extent of improvement afforded by the addition of the large
capacity supply which is particularly prominent at lower
pressures, i.e., below about 90 psig.
4) Proiected Energy Consumption
The importance of a capability for effective operation
at the lower range of supply pressures which characterizes
the invention is illustrated by the following Table IX which
shows a pro;ected consumption of energy, expressed in kilowatts
per minute, for a loom equipped with the system of the invention
and operating at 1000 picks per minute for nozzles having
throat areas of 11 mm and 16 mm2, either supersonically
-116-
. ,, . ~ . . .. .. . . . . .. . . . . .
~ r
contoured or straight, with a pulse duration of 15 ms and
a large C86~'3~ capaclty supply.
Table ~X
Pro~ected Energy Consumptlon
(:~llowatts)
_ Supply Pressure (psi~) _
50 60 70 80 90 100 110 120
11 mm _
2 .323 .447 .579 .721 .873 1.03 1.203 1.378 1.56
16 mm --
Nozzle Area 473 .649 .839 1.04 1.26 1.50 1.73 1.99 2.28
Thus, the increase in power consumption is not a linear
;~ function of elther increasing head pressure or noz~le throat
area but an exponential function, the energy consumption at
90 psi supply pressure, for example, being more than three ~ `
times the consumption at 40 psi.
h. "Balanced ~ode" of Operation ~ -
.
Tn the preceding discussion of the operation of
the system of the invention, it is suggested that the seIection
of a2 a relatively high level of head pressure is advantageous
in achieving particularly fast air arrival times, which
gave the capability of minimum wef~ arrival times and
offered ma~imum potential for high operation speeds with
b) a minimum effective duration fDr the air pulse, i.e,,
about 15-20 ms, in order to reduce ener~y consumption as
much as possible. When operating in this manner, observation
has shown that during flight, the leading end section of the
we~t tends to become bunched upon itself as it encounters
the resistance of the stationary column of air within the
guidance tube, and it was reasoned that this problem was
aggravated by the fact that the metered and stored length -
of weft had been withdrawn from the weft storage drum section
within a period of time signifi~antly less than the time
required for that weft end to actually traverse the width of
33 the loom.
~117
~7~65
U~ually, as the projected weft length completes its traverse,
the bunched-up leading section will e~rentually straighten out and arriYe at
the reception side of the warp ~hed but, occasionally, say one to two times
per 1000 or so picks of operation, the bunched- up leading æection apparent-
S ly becomes sufficiently tangled as to resist straighterlhlg out under thefairly light inertial forces working upon it. When this condition develops,
the leading end of the weft does not actuall,y reach the fa~ side of the shed
for engagement by the reception tube there, and if the weaving is continued,
the result is the introduction of a defect in the fabric being woven. As
described, the system of the in~ention preferably includes a weft arrival
detection unit which serves to detect the failure of the weft end to arrive
at the reception nozzle and halt the weaving operation automatically to
allow for the intervention of a human operator to correct the fabric defect,
but this results in loss of production due to the "down ti~ne" needed to
correct the defect.
Furthermore, the air pulse injected by the nozzle into the
guidance tube actually moves through the guidance tube as a kind of
column corresponding in length to the duration of the pulse. Thus, the
"air arrival" times emphasized in preceding description represent arrival
~20 c-f only the leading end of the column and air continues to advance through
~he tube until the trailing end of this column passes out the tube. If the
weft tra~reling through the guidance tube slows down or stops while the
trailing e~d of the air column is still advancing rapidly, it has been found
that the free weft end can be blown "off course!' and out of the guidance
tube egress slot 49 instead of continuing through the tube bore. lndeed if
the air column is still at full speed after the weft has been entirely with-
drawn ar.d its free end held in the reception tube, a "backlash" can occur,
28 pulling the free weft end out of the reception tube and blowing it out of
-118-
, . , . , " , ., ,,,, ,,, , , .. , ~, . ., . ... , . , . , , ~
6~i
~ube egress 610t 49. Once the weft free end has escaped through slot 49,
a weaving defect, i. e., "mispick" ia inevitable.
The bunching and tnagling phenomenon has been found upon in-
Rpection to always occur on the leading end section, i. e., the last 2-3",
S of the weft length and one possible ~olution to this occasional problem
would be the addition of enough extra length to the weft that it will reach
the reception side of the warp e~ren when the bunching phenomenon occurs.
Obviously, however, with the addltion of $his added length during e~e~y
cycle (it bemg impossible to predict in advance a paTticular cycle during
which the phenomenon might occur) the amount of waste produced during
weaving is correspondingly increased. Consequently, this solution violates
an important ob~ective of the inveDtion maximizing efficiency and mini-
mizing waste.
It~has been discovered that the bunching pheno~nenon can be
better avoided by ad~usting the weft insertion thrust and/or resistance so
as to arrive at a mode of operation which is more "balanced" in the sense
. .
of matching the time required to completely withdraw the stored weft
length from the storage ~ection with the time required to completely pro-
ject the end of that wet length across the full width o~ the shed~ Re-
duction of the n~ zle head pressure, of courae, results in a reduction in ~-~
the thrust imparted to the weft, other conditions being equal, and there
can be definite practical advantage~ in selecting a nozzle head pressure of
about 60-70 psig. Most textile mills currently in operation already ha~e
available for normal mill functions compressed air at a pres6ure of about
75-80 psig, which is fully adequ ate to achieve head pressures of the
desired 60 psig or so level, and there are obvious practical advantages in
being able o utilize the existing mill cornpressed air supply. Otherwisc,
28 expensive special -ompressing equipment would have to be purchased and
- l 1 9 -
, . ~ ., . .... , .. ~ . ., . ~.. ..
136~
installed to produce the requ;red higher pressure level which would greatly
add to the cost of putting the present invention into actual practice.
When operating at a head pressure of about 60 p~ig as just
indicated, the thrust imparted to the yarn is ~till ~omewhat excess from
the ~tandpoint of achieving the balanced ~node of operation described above
and additional measures need to be applied.
Several wayæ are available for balancing weft withdrawal time
with weft projection time. On the one hand, the efficiency of the nozzle
in tran mitting its pressure force~ to the weft end can be reduced a~, for
example, by extending tbe distance between the end of the yarn feed tube
and the exit plane of the nozzle, say increasing the projecting length of
feed tube to about 3/8" instead of about l/g" as before, and this is present-
ly the preferred technique. Alternatively, the resistance or "drag" of the
weft lePgth during its withdrawal from the weft storage unit can be in-
crea ed either by increaæing the distance between the balloon guide and
the end of the delivery drum so as to lengthen the unwinding balloon and
increa~e its diameter or by adding tension to the weft upstream of the
inlet of the nozzle.
The effect of the balanced mode of operation is to "stretch"
the energy forces applied tc> the weft over a longer period of time with the
re6ult that the withdrawal of the stored weft length does not take place as
rapidly as before but instead occurs at a rate substantially matching the
rate at which the weft is advancing through the warp shed. Therefore,
overruning of the leading end by the on-coming we~ length i4 virtually
eliminated with consequential disappearance of the bunching phenomenon.
Optimum performance is obtained where the free weft end
exits from the end of the guidance tube before the stored coil~ of wet have
2g been cornpletely withdrawn from the drun~ storage section; that is, the
~ 1 20 -
1365
weft end leaves the guidance tube before an initial tenBion rise is detected
by the tension detector 338. Ideally, the arrival of the weft end within the
reception tube, as signaled by the photoelectric detection means, occurs
virtually simultaneously with the departure of the last of the stored weft
from the drum storage unit; that i~, the detected tension rise and wefS
arrival signal are virtually coincldent.
Operation with head pressures consistent with available mill
line prebsures has a further practical advantage, namely, a considerable
reduction in the tirne required for the pulse to decay from its plateau level
back to zero. In the "balanced mode" operation, the pulse decay can be
reduced to about 7 ms from about 12 ms as tgpically characterized the
"high impulæe" mode. This mades possible the prolongation of the
plateau phase of the pressure pulse without concomitant risk of continu-
ation of the pulse after the weft has in fact arrived at the reception side
of the shed~ Mention has already;been made of the fact that if the pulse
persists after the weft iB in fully straightened static condition, the weft
vvill be buffeted about severely leading to its degradation if not complete
disintegration. In the balanced mode the pressure pulse can be "stopped"
60 to speak, in roughly ~half the time required for the hiaher pre 6 sures;
it thus is easier to insure that the pulse has ended before the weft has
:
achieved a stationary condltion within the shed. In general, it is preferred
that the pulse be completely decayed about 2-3 ms prior to the arriv~l of
the leading weft end at the reception side of the loo~n.
It has been discovered that the sacrifice in weft arrival times
obtained in accordance with the balanced mode of operation is at most
small. For instance, with a head pressure of 60 psig, a pulse duration
extended to about 30 ms, and the preferred weft feed tube projection of
Z8 3/8'J, air arrival times equal to about 23 ms and weft arrival times of
- 121-
.. . . .... ... .. .... .. . .. .... . .. ...... . .
. .. .. .. .. .. ..... ... . . . . .
about 32 rns can be consistently attained with ease.
i. Other Conventional Factors
There exists in the operation of the system invention factors
other than those described above which are not peculiar to the invention
but are shared with prior art systems, 60 that full description of the role
th0y play is not necessary here. One such factor is the nature of the
strand itself and in common with prior art air weft insertion systems,
the system of the invention works effectively principally only with relati~e-
ly rough surfaced wefts. Such wets are represented by conventional
twisted spun staple yarns, either natural or synthetic, and presumably by
textured surface synthetic filaments as well. Smooth suTfaced mono-
fila~nents have not been examined so farO
,
The influence of the siæe of the weit has not been examined
thoroughly but the capacity of the various nozzles described abo~re is
; ~ ~;15 suffic1ent to readily accommodate considerable range of conventional
deniers and no difficulty i5 anticipated in the utilization of the in~entive
.
ystem with such yarns, given the potential for supply pressuTe variation
inherent in the present system. Wets tested to date range from 12~s-50's
- ~
cotton staple yarns, and all have been satisfactorily woven without change
in operating conditions.
A further factor is the diameter of the weft guidance tube.
Rough bench tests have established that a certain minimum tube diameter
is s~eeded for the weft to be effectively transported through the entire tube
length. For example, with the various noz~les mentioned above, an inner
bore for the tube of 1/2" is not adequate; only the large throat area
- nozzles (32 mm2) are capable of delivering the strand entirely through a
1/2" I. D. guidance tube and even with these no7.æles, the weft arrival
Z8 times are quite long, e. g., in the order of 6G ms. On the other hand,
- 122..
tube bore diameters of 3/4" are entirely satisfactory and all of the
numerous tests appearing above were carried out with a tube of this
dimension, as stated. The bore diameter could likely be increased
hlrther without drastic consequences on operational effectiveness, but no
particular ad~rantage is seen in doing 50. A reasonable theory is that if
thè tube bore diameter iY too small in relation to the nozzle outlet dia-
meter, the tube tends to unduly confine the air pulse colurn~ emitted by
the insertion nozzle, in the 6ense of frictionally resisting its passage
and/or interfering with its freedom to undergo some e~?ansion upon emer-
gence from the nozzle opening. Howe~er, so long as the nozzle diameter
is ~ufficiently large to afford the air pulse a minimum dynamic freedom,
satisfactory operation is possible and larger diameter tubes would, of
course, afford greater freedom. On the other hand, the guidance tube is
a critically important part of the system and if omitted, the weft pro-
~,
jection capability ~f the nozzle is extremely limited and far less than the
width of any normal sized loom. The applicants suspect that a similar
relationship exists between prior art no~les and tube diameter, although
.
no express recognition of this fact has a~ yet appeared in the published
art to applicants' knowledge.
It follows from the preceding com~neIlt that the present system
i~ de~igned for as30ciation with ~normal-slzed~' looms, i. e., about 48" in
width or greater. Special narrow width looms are known, e. g,, ribbon
looms, eword loo~ns and the like, but high speed operation of such looms
i~ poss;ble in other ways, i. e., by means of mechanical transports, e. g.
swords, because of their much less demanding technological require-
ment~, and little reason exists for lesorting in such narrow looms to the
more sophisticated approach of the present system~
28 Further with regard to the guidance tube, mention has already
- 1 23 _
~ '
been made of the practice in thc invention of mechanically abrading the
interior surface of the guidance tube bore to impart a reaæonable degree
of polish or smoothness thereto, as by ~neans of honing. Air and weft
arrival times may be reduced significantly more with internally polished
tubes as compared to tubes w~th surfaces obtained by conventional casting
or molding. HoweYer, for the balanced mode of operation honing has not
been necessary and careful as~embly of the elernents by means of a jig
produces satisfactory registration.
The axial thickness and frequency of the segments making up
the guidance tube is generally determined by the requirement that the
elements making up the tube be sufficiently close together as to effectively
confine the air flow, which can limit the ~i7e and number of the warp
threads, but this limitation applies to any system utilizing a guidance tubeA
Segmer.ts having an axial dimension of about 1/8" and spaced apart about
20/1000 - 35/1000 have performed well.
j. Specific Exam~le
A shuttle loom of 48" width converted according to the present
invention is used to weave print cloth from 40's warp threads spun from a
35/65 lnixture of cotton and polyester st2ple fibers and 35~s weft threads
spun frorn the ~ame 35/65 mixture of cotton and polyester staple.~ The
total number of warp threads is 3750 and the reeded width of tbe warp is
51. 5~A The loom is equipped ~ith the nozzle of Fig. 5 including the large
capacity accumulator and the control unit is the modified mechanical em-
bodiment of P'igsA 11-13. The nozzle is a supersonically contoured
nozzle having a throat area of 11 mm2, a Mach number of 1. 5 and 5xD ex
tension barrel giving a head pressure of 70 psig. The end of the weft
feed tube projccts 3/8" beyond the end plane of the barrel in contrast to
28 the feed tube arrangement in the various tests in the preceding description
- 1 2~
~"5~
~rhere the feed tube terminated in all cases at the exit plane of the nozzle
orifice exclusive of any extension, io e~ 9 the plane designated 88 in Fig. 4.
The loom is operated at 318 picks per n~inute.
A representative cycle o~ operation of the above loom is de-
S picted in the strip chart of Fig. 35 which shows in timed relationship the
~ollowing wave forms: a the activation, i. e., opening and closing of the
weft delivery clamp C, 330" b the head or stagnation pressure of the in-
6ertion nozzle; c the wet delivery tension as detected by the tension de-
tector 338; and d the arrival of the weft at the reception tube, as detected
by the photoelectric array. The clamp opens at 140, remains open for
a period of 40 ms and closes at 217. The insertion no~zle is activated at
145 for a period of 34 ms, the head pressure subsiding to starting level
at about 220.
With the activation of the nozzle, the tension in the weft in-
creases from its "previou~ noise level" almost coincidentally with the
nozzle activation and perceptible peak in weft tension occurs at 208 in-
dicatirg the complete withdrawal of the ~eft from the arum storage
~ection, the weft tension indicator thereafter ~ubsiding to its inherent
"background" level. The arri~al of the weft end at the photodetector
occurs at 208, the subsequent peaks e in wave form d being caused-by
"fluttering~ of the weft end in the reception tube and of no signiicance
The weft arrival time is 36 ms and the air arrival time tderived by other
means) was obser~ed to be 28 ms. In this description, the abbreviations
ms represents milliseconds and psig sepresents pounds per square inch
gauge.
28
-125~
