Note: Descriptions are shown in the official language in which they were submitted.
1146~46
Field of the Invention
This invention relates to the field of loom stop moSions and is con-
cerned more particularly with a combined warp and weft loom stop motion
which can be selectively timed 80 as to ha~t the loom in the event of yarn
breakage at different point~ in its operating cycle dependent upon whether
the breakage is of a weft or warp yarn, the stopping points being selected
to facilitate repair of the particular breakage.
Background of the Invention
Looms for weaving cloth have for many years been conventionally
equipped with stop motions for detecting breakage or other loss of tension
in any of the warp threads as well as the breakage or failure for other
reasons to in~ert a filling thread into the ~hed of the loom defined between
opposed groups of warp threads. While the~e stop motions can take
variou~ forms, they are usually designed to close electrical contacts
when any warp or filling thread breaks and thereby emit a control signal
which is utilized to stop or "knock-off" the mechanical drive of the loor.
Ideally, warp and filling breakages have different requirements as
regards the point in the operative cycle of the loom at which the breakage
or other defect causing the stoppage can be repaired. The warp threads,
of course, pass through the eyeY of the heddles, which are shifted up and
down to separate the groups of warp threads and form the weaving shed,
and since any broken warp thread must be rethreaded through its corres-
ponding heddle eye, it obviously will be easier to accomplish such re-
threading whcn the heddles are in or near their closed position, and their
2S eyes are ~ubstantially aligned with the median plane o the warp, rather
than when the heddles are open or separated and the warp threads are
stretched apart. Thus, the optimum stopping position for repairing a
28 warp thread breakage is with the lay of the loom approaching front dead
- 2~
11~6~46
center but not so close to be front dead center that the weft thread would be
beaten up into the fabric, say at about 320 of the loom cycle starting from
front dead center. ~
Contrariwise, the filling thread is inserted into the shed while the
warp groups defining the shed are well separated apart and removal of a
broken weft thread can most easily be carried out when the shed is reason-
ably open. Once the shed begins to close, as the heddles move together,
the warp threads begin to grip the incomplete weft thread which makes its
removal much morè difficult. ~hus, the optimum position of the loom for
purposes of repair of a filling defect iswhen the lay of the loom is adjacent
to back dead center.
The stopping position of the loom, particularly in case of warp break-
age, mu~t also take into account the avoidance of so-called "8et-marks"
in the woven fabric. If the lay of the loom is allowed to stop too near front
lS dead center and the loom is again started at that point, the portion of the
cycle remaining until front dead center is too short for the lay to build up
to its normal operating speed and momentum and thus as the lay reaches
front dead center, the reed carried thereby will impact against the last in-
serted weft thread with a force less than normal. This difference in beat-
up force will appear in the fabric and cause what is referred to as a "set-
mark". Traditionally, the practice in the art has been for the loom attend-
ant to rotate the crankshaft of the loom backwards by hand, using a large
wheel provided at one end of the crankshaft for this purpose, so as to re-
locate the lay and other operative components at a starting position
effective to avoid the set-mark problem.
In addition, there exist certain circumstances under which it bccomes
desirable to have the loom insert a single pick and then be brought to a
28 halt. Single-pick operation i8 useful, for example, in facilitating the
~1~6~6
repair of a defective pick in automatically positioning the loom on signal
in position to enable the repair to be corrected with a minimum of
difficulty. In the past, "single-pick" operation has been carried out under-
the control of the operator, who if need be rolls back the loom crankshaft
to the appropriate starting position and then operates the loom to insert a
single pick or weft by direct manipulation of the loom operating handle.
Objects of the Invention
A principal object of the present invention is the provision of a
simplified combined loom stop motion which is responsive to both warp and
filling breakages and is capable in the event of either such breakage of auto-
matically bringing the loom to a halt in a condition optimally suited to the
correction of the particular breakage.
A further object of the invention is a combined warp and weft stop
motion which is selectively adjustable to cause stoppage of the loom in
different positions according to the type of defect which occurs.
Another object of the invention is a provision of a loom stop motion
which can be utilized for achieving automatic single pick operation.
Brief DPscription of the Drawings
These and other objects of the invention will be more fully revealed
by the following description of the accompanying drawing~ in which:
Fig. 1 is a side elevation in somewhat diagrammatic form of one em-
bodiment of the combined stop motion of the present invention in operative
position, and
Fig 2 is a plan view looking down substantially along line 2-2 of
Fig. 1,
Detailed Descriptlon of the Invention
In Fi.g. 1, the combined stop motion of the present invention is seen
28 in side elevation in o?erative position mounted on the loom, with, however,
_ ~ _
1146~3~6
only those components of the loom which are directly associated with the
invention; namely, the crankshaft and operating handle, being shown as is
nece3sary for following thi~ description. In Fig. 1, a pair of control
solenoid housings 10, 10' are mounted on a bracket 12 which iB fixed to a
convenient stationary part of the loom (not shown). One of these solenoids
10 is wired to receive the control si~nals fro;n a weft or filling breakage
detecting means while the other 10' is wired to receive the control signals
fron~ a warp breakage detector means, neither detecting means being
shown. The construction and operation of these detecting means have no
significant bearing on either the structure or operation of the present in-
vention and they can, accordingly, be of any of the conventional detection
systems used for this purpose, the only requirement being that théy initiaie
and deliver separate control pulses when a weft or a warp breakage,
respectively, occurs. Each of the stop solenoids 10, 10' has its armature
(not seen) connected to an exteriorly projecting operating lever 14, 14' so
that upon energization of either solenoid 10, 10', the corresponding opera-
ting lever i6 rocked upwardly and remains so until the solenoid is de-
energized to return the lever to its starting position.
At its free end, each of operating levers 14, 14' has a connecting
wire 16, 16' pivoted thereto which extend generally vertically downwardly
in more or less parallel relation to a common '~nock-off" head 18. Since
the distance between the points of connections of the lower ends of wires
16, 16' may vary in practice, preferably each connecting wire includes a
serpentine section, as at 20, 20' which can be easily bent to make the rods
2S longer or shorter as circumstances may dictate.
Mounted at the left-hand end of the common "knock-off" head 18 for
limited pivotal movement relative thereto between a generally horizontal
28 position and an upwardly tilted position (shown in dotted lines) are a p~ir
114~6~6
of knock-off ingers 22, 22' which are dispc>sed in spaced parallel relation
to one another in the dimension perpendieular to the plane o Fig. 1, as is
evident in the plan view of Fig. 2 . The shape of fingers 22, 22' is not of
particular importance, the only requirements being that they have adequate
strength to withstand substantial mechanical impact applied against their
extreme outward ends. To this end, the fingers, as seen in the drawings,
can be given a roughly dish-shape, with one side edge extending nange-
like vertically as at 23, 23' for improved resistance to bending in bo,h
planes. The flange edges 23, 23' can serve as a convenient p~int for en-
gagement with the lower ends of wires 16, 16', each such edge being per-
forated for engagement with hooks bent for that purpose in the lower wire
ents,
A supporting stub shaft Z6 i8 affixed to a pair of the loosn frame (not
shown) and on shaft 26 are pivoted a pair of identical rocker arms 28, 28'
extending generally vertically upwardly from the axis of shaft 26 in
axially spaced apart relation, again best seen in Fig. 2. At their upper
ends, each rocker arm 28, 28' carries a follower roller 30, 30' thereon
and intermediate their ends, each arm carries a rightwardly projecting
hammer 30, 30'. The axes of the hammers and knock-off fingers are so
related that they lie in pairs, one hammer and one finger, in generally
common planes in one direction (the vertical direction, as appears in Fig.
- 2). In the other direction ~i. e., as shown) axes of the respective pairs
of hammers and fingers are offset or separated so as to be out of regis-
tration when the knock-off fingers are actuated in the solid line position
seen in Fig. 1 but are in registration when the fingers are situated in the
dotted line upwardly displaced position. The front ends of the hammers
are preferably notched or otherwise contoured for non-slipping engage-
28 ment with the ends of fingers 22 22'.
1146~346
Each of the follower rollers 32, 32' rides on the peripheral ~urface
of a corresponding cam 34, 34' mounted in axially spaced relation on the
crankshaft of the loom 36 for rotation therewith. The cams 34, 34' are
identically contoured so as to each provide a high region or lobe 38, 38'
at one point thereon which is preceded by a ramp 40, 40' and followed by
a gradually tapering transition 42, 42' which merges into a low region 44,
44' equal to about 180 of the cam periphery. While the cam contours are
preferably the same, they are arranged in out of phase relationship on the
loom crankshaft so that the respective lobes thereof move into contact with
the corresponding follower rollers at different points on the loom cycle.
The rocker arms are biased into contact with the cam peripheries, as by
springæ 45, 45' and the starting positions of the cams on the crankshaft
can be adju6ted individually by means of set screws or the like (not shown).
In general, the geometry of the cams in relation to the followers,
rocker arms and knock-off hammers is such as to cause each rocker arm
and associated hammer to pivot between a retracted position spaced away
from, i. e. leftwardly in Fig. 1, the extreme tip of its associated knock-
off finger when the follower roller rides on the low section 44, 44' of the
cam, and a projected operative position in which the knock-off harr~ner
overlies its corresponding knock-off finger, as the latter is in full line
position, when the follower roller makes contact with the high portion or
lobe 38, 38' of the cam.
The knock-off head 18 is supported for horizontal reciprocating
movement on a guide bracket 46 which is fixed on stub shaft which termi-
nates at its upper end at a more or less frusto-conical shaped guide tongue
48 of reduced thickness so as to project through a vertical slot passing
through at least the mid-section of thc knock-off head 18. The knock-off
28 head can, for example, be constructed of two matching side sections 47,
~46~46
47! united in 3paced apart relation so as to define a vertical slot 49 ~Fig.
Z) for penetration by tongue 48, each such qide qection carrying its own
rigid knock-off finger. Below tongue 48, bracket 46 has increased thick-
n¢~s, thereby forming opposed shoulders 52 (only one of which is visible in
the drawing) and knock-off head 18 is thus supported for horizontal recipro-
cating movement on bracket 46 generally horizontally along a path fixed by
tongue 48. A tension spring 54 stretches between tongue 48 and head 18 to
bias the latter toward the let in Fig. 1.
The end of knock-off head 18 opposite to fingers 22, 22' is affixed to
the end of a rigid knock-off rod 56 which at its opposite end is pivoted to
thè control handle 59, usually referred to as the "shipper" handle 59, of
the loom, the connective arrangement being such that the solid line
pc!sition of the knock-off head corresponds to the "on" or operating position
of the operating handle. In this particular case shown, the shipper handle
59 occupies "on" position when pivoted clockwise and "off" position when
swung counterclockwise, and the pivot axis of the handle itself, therefore,
lies above the point of pivotal connection of the knocX-off rod 56 thereto.
The arrangement just described operates in the following manner:
While the loom is operating normally, the actuating levers 14, 14' of the
respective stop solenoids 10, 10' remain in depressed position so that
knock-off head 18 likewise occupies a depressed normal operating position
- ~hown in solid lines in Fig. 1. As the crankshaft 36 rotates, each of the
cams 34, 34' turns 360 during each weaving cycle and cause3 each of the
rocker arms 28, 28' to oscillate back and forth in timed relation to such
rotation. The hammers 30, 30' thus are consequently displaced to and
fro in relation to the corresponding knock-off fingers, but as long as the
knock-off head remain~ depressed or disabled, hammers 30, 30' pass
28 freely above the upper limits of iingers 22, 22' without contactina the
1146~46
same, and ;he weaving continues without interruption. When, however,
either a wet or warp yarn breaks, the control signal generated by the
corresponding conventional breakage detecting means i8 applied to the
corresponding stop solenoid which actuates its armature to pivot the corres-
ponding actuating lever upwardly. This lifts the corresponding lift rod 16,
16', thereby pivoting the knock-off fingers 22, 22' connected thereto up-
wardly into the oscillating path of the associated hammer 30, 30'. Then,
as the cam shaft continues to turn, the rocker arms will be rocked in their
turn toward the corresponding knock-off finger so as to impact against
such finger in its upwardly displaced position, creating a mechanical im-
pul~e which is transmitted to knock-off head 18 and through rod 56 to the
loom shipper handle driving it to its "off" position, causing the loom to
~top.
Since each of cam9 34, 34' corresponds in function to a particular
type of defect, either warp breakage or weft breakage, and since the
relative positions of the cams on the cranlcshaft can be adjusted, it becomes
possible to control the timing of the knock-off action selectively to match
the needs of the particular kind of defect. Such adjustment will naturally
have to be made on a loom by loom basis; the driving mechanism of each
different type of commercial loom has its own peculiar braking time con-
stant and the effect of inertia will to some extent be different for each
given loom but by observing the inertia and the braking time constant of a
specific loom, the respective cams 34, 34' can, by trial and error, be
arranged on crankshaft 36 so that they result in the loom coming to a halt
at the proper points in its operating cycle for the defects in guestion. In
the course of repairing a defect, the defect sensing means will be returned
to its normal operating position, and the respective stop solenoids are re-
28 set to their operating position, thereby returning the knock-off head to its
_ 9 _
- ~1461346
depressed or disabled normal operating position before the shipper handle
i8 pivoted to restart the loom. lt should be stated that the peripheral dis-
placement of cams 34, 34' seen in Fig. 1 is selected primarily to distin-
gui~h between the two cams and is not intended to represent actual illus-
trative operating positions thereof which would in any case have to be
tailored to the particular loom, as already stated.
It can be added, howe~er, that in general~ the optimum stopping
point for purposes of repair of a filling defect is at approximately 200-210
of the cycle, while for a warp defect, the best stopping position is around
320 of rotation, keeping in mind in the latter case the need for the lay to
be sufficiently remo~red from front dead center as to minimize the chance
of a set-mark.
The combined stop motion of the present invention is also ideally
adapted for utilization in fùrnishing the loom with the capability for single-
pick operation, i. e. the insertion of a single weft and then coming auto-
~natically to a halt. To this end, one of the stop solenoids 10, 10', prefer-
ably the weft solenoid 10 for reasons to be explained shortly, is connected
through a flip-flop 60 and a manual pushbutton switch 62 to a source o
control current 64. When pushbutton 62 is closed either just before or
simultaneously with mo~rement of the shipper handle 59 to "on~ position,
flip-flop 60 is activated so as to actuate the stop solenoid 10 which causes
the knock-off head 18 to be lifted to an enabling position with one of its
knock-of fingers in position to be engaged by a knock-off hammer during
the immediately following cycle of the loom. The flip-flop 60 can be re-
set in any convenient way and, for sake of illustration, the extreme lower
end of the shipper handle is provided with a magnetic tip 66 which is
adapted to cooperate with a magnetically attractable switch 68, such as a
28 Hall effect switch, situated adjacent the path of the shipper handle end when
- 10-
~l146~6
the latter is in its full "off" position. Thus, when the stop motion
functions to knoclc off the loom due to actuation of ~he stop solenoid, the
moven~ent of the shipper handle to its off position automatically resets
flip-flop 60 in readiness for the next cycle.
Given the fact that the loom stops fairly late in its cycle in the
event of the occurrence of a defective pick or warp breakage, stoppage of
the loom within the same cycle wherein the defect occurs would impose
enormous stress on the loom components and, consequently, it is in-
tended in the practice of the present invention for the inertia of the loom
10 ' to carry its operating components, especially the lay, well into the sub-
- sequent cycle, stopping at one of the predetermined points therealong as
~pecified above. This means, of course, that when a filling defect has
occurred, the defective pick has already been beat up into the fabric and
the heddlés have shifted position for the insertion of the following pick
which has already been inserted across the open shed. In order to repair
the defect pursuant to this invention, the inserted weft for the next cycle
i8 removed by hand, the loom having been brought to a stop in po~ition
appropriate for such removal. Next, the heddles must be returned to the
position occupied by them when the defective pick was inserted and the
single pick operation feature of the present invention enables this to be
done by mere actuation of the single pick control by the loom attendant.
The heddles are thereby reversed, open~ng the shed to enable the defect-
ive pick to be removed without interference. In the meantime~ a fresh
pick has been inserted into the shed opened by reversal of the heddles and
the lay has been positioned ready to resume the normal weaving operation.
In order to minimize the opportunity for set-marks to be created when the
loom is restarted, it is preferred that the weft stop solenoid be integrated
28 into the single pick operation, receiving the control signal from the
. _ _ . . _.. _ . _ . ___ , . . , ... , .. . . .. _ . . " .. " .........
~146(346
flip-Ilop 60 and thereby stopping the loom in the vicinity of 200-220 of its
cycle, which i8 ideal for eliminating set-marks.
.A further consideration involved in the selection of the stopping
point of the loom ollowing single-pick operation as well as or a wet de-
fect, i8 the effect of the stopping point on the manipulation o the weft it-
~el. While the system o the present invention can be employed quite
successfully with conventional comn~ercial looms of all types, it is also
especially useful in association with a loom of the fluid insertion type, and
while various different looms operating in this way have been or are being
designed, and all can in principle utilize the system of the invention with
good results, a particular preferred fluid weft insertion loom is disclosed
and claimed in application Serial No. 356,160 filed in the name of Charles
W. Brouwer et al on July 15~ 1980 and commonly assigned herewith, to
the tescription of which reference may be had for a fuller understanding of
its operation. In the loom of application Serial No. 356,160, air or other
inert compressible medium is delivered under predetermined pressure to
the throat of an insertion noz~le and an important feature of that loom is
tbe manner in which the flow of air to the nozzle is controlled to limit the
duration of the air flow in the manner of a pul~e, the pressure of the air
in this pulse being sufficiently high that this pulse contains all of the energynecessary to transport a typical yarn across the width of a typical commer-
cial loom, say at least about 48". Because of this high air pressure, the
weft yarn passing through the nozzle throat for insertion thereby into the
warp i8 subjected to very substantial stress, particularly since the pre-
ferred nozzle of the above-identified application is designed to impart
supersonic ~relocities to the air flow downstream of it~ throat and the yarn
i8 exposed to such high velocities.
28 It has been found that if the yarn i~ exposed to such intense air flow
~ 12 -
~146~46
when it i8 being re~trained against movement, either before or after its
insertioD into the loom shed, the stress upon the stationary yarn will be
deleterious to that yarn. For this reason, th0 stopping point of the loom
must be coordinated with the timing of the pulse or other ilow of the wet
insertion medium 60 as to avoid stopping the loom, while the pulse control
device remains substantially operative. Damage to the yarn is minimized,
however, if the earliest stopping point of the loom is subsequent to termi-
nation of the pulse of weft inserting medium; although in practice, some
overlap is permissible provided the pulse is in its terminal phase at that
point and is already undergoing a loss in pressure on the way towards
imminent shutdown.
There i8 another advantage of the system of the invention which is
of significant merit in actual commercial practice. The stopping positions
of the heddles of the loom, which typically project in their open or spread
position vertically well above the body of the loom and thus are readily
visible at some distance, are different with the two kinds of defects in
question, the heddles stopping in closed or together position for a warp de-
fect and in well separated or open condition for a weft defect. Hence,
simply by observing the position of the heddles, the operator is immedi-
ately informed as to the kind of defect which requires attention and may,
therefore, organize the approach to be taken for repair to minimize wasted
time and effort.
The location of the present stop motion on the loom frame is ob-
viously subject to some variation. As mentioned above, the driving cams
are preferably mounted directly on the loom crankshaft, which might in-
fluence its location, but this is not essential because the cam~ could be
mounted elsewhere and driven in synchronism with the crankshaft by ~neans
28 of intermediate gearing, a timing belt coupling or the like. One useful
1~6~6
location i~ adjacent the inside of the side frame member neare6t the
6hipper handle ~which i8 UBUally actuated at front corner but well clear of
the path~ of movement of operating components, such as the heddles and
lay) to avoid interference therewith. The in~tant sg~tem ob~riously takeR
up relatively little space ~ince the axial thickness of its individual elements,and therefore the overall axial thicknes6, need only be such as to achieve
the required mechanical strength and durability for long term ~peration.
From the foregoing it will be seen that the pre~ent invention pro-
-~naes unique and ad~rantageous method and apparatus for stopping a loom
upon detection of a warp or filling defect with the variou~ mechanisms of
the loom, particularly the lay and harnesses, in the optimum position for
correction of a warp or filling defect. In practice with the prior art the
repair of filling defect~ i8 a laborious and time-consuming task. For ex-
mple, in effecting such repairfi on conventional ny shuttle looms it has
been nece~ary, once the loom is ~topped, for the loom attendant to rotate
the loom crardc~haft baclcward~ manually to relocate the lay and other
operative loom component~ at a desired starting position to avoid the ~et-
~rk problem. Next, the operator is required to remove the faulty pick.
Thereafter, the operator grasps and holds the filling end from the bobbin
in the ~huttle with one hand while manually propelling the shuttle through
the ~hed to insert a "good" pick in the shed for beat-up.
- In clear contradistinction to the foregoing, the present invention
operates upon the detection of a faulty pick to ~top the loom automatically
on the next cycle after the faulty pick has been beat into the fabric. This
~topping, ae previou~ly mentioned, occur~ when the loom is approximately
270 into the next cycle. When the loom is thus stopped the operator
manually removes the pick then resident in the shed as fully explained in
28 prior cited patent application Serial No. 3~6,160. At this point,
~; \ ~ ~ 14 -
~6~6
since the heddles mu$lt be reurned to the pOSitiOI-S they were in when the
faulty pic~c was inserted into the fabric, that i6, the heddles must be re-
versed to permit ready removal of the faulty pick. This is achieved by
actuating pushbutton 62 which automatically operates the loom through one
cycle with the loom stopping at approximately the 200-220 position. In
the course of this single pick operation of ihe loom the shed is reversed to
permit easy manual removal of the faulty pick from the fabric while, at the
same time, causing a fresh pick to be inserted into position in the shed.
Additionally, the loom mechanisms are optimally positioned to beat up the
further pick once the loom is restarted with the lay impacting against the
further pick under its full operating force to thereby preclude a set-mark
in the fabric at the locus where the filling repair has been made. There-
fore, filling repairs as just described can be effected some three or more
time~ faster in practice with the present invention than is possible with
prior art techniques while, at the same time, aYoiding undesirable set-
mark6 in the woven fabric.
While a preferred embodiment of the invention has been described,
with various preferred aspects being identified, it will be understood and
appreciated that the invention is not intended to be limited in its scope to
these preferences as other alternatives and options will be readily avail-
able within the skill of the art and will be obviously suggested by what has
been specifically described and illustrated. Therefore, the invention is
not intended to be confined in its scope to any specific characteristics ex-
cept where expressly required by the accompanying claims.
;~8
~ 15 -
