Note: Descriptions are shown in the official language in which they were submitted.
1146~:?47
Back~round of the In~,er-t;on
. .
This in~ention relates to the operation o a loom and relates more
particularly to the method and means for monitoring and controlling the
quality of fabric produced on a loom.
In order that fabric of acceptable quality rnay be made t-here are
certain conditions in the wea~ring equipment that need be controlled. For
example, defective feed of weft OT warp yarns, broken yarns, or missing
or improper filling yarns (picks) may result in defects in the fabric. It
has been conventional in the art to have sensors and control mechanisYns
on the looms to stop the looms for manual correction of some defects.
However, stopping the loom for fabric repair does not assure that the
fabric ultimately woven will be of perfect quality. For example, since an
improper pick is removed and replaced under operator control and since
it i8 necessary to manipulate the fabric advancing mechanisms to insert a
replacement pick, considerable opportunity for improper repair exists.
Hence, it has been customary to inspect the fabric after it has been wo-~en
and removed from the loom and, if too many defects appear in the fabric,
then it is graded to a lower quality.
It i9 an objective of the present inYention to predict the fabric
quality as it is woven and to operate the looms in a fashion such that
fabric quality can be automatically and continuously predicted. There-
fore, a problem resolved by this invention is the prediction of the quantity
of potential fabric defects a~ the fabric is being woven with concomitant
provision within the loom of means for processing predicted quality so
that most fabric need not be furthe~ inspected.
Furthermore, the output efficiency of looms is significantly
deteriorated by the requirement that the looms be stopped for cor~cction
2~ and restarting under all conditions. Thus, in a mill with perhap~; f~rty
~146~47
looms under surveillance of a single operator, several looms may be
taken off line sirnu~taneousl5r while the fabric on only one can be repaired
at a time. Accordingly, it is a further objective of this invention that
defects be sensed and processed in such a way that the output quantity of
the loom is increased and that stopping for repair can be avoided when-
ever looms are running at a low error rate.
To achie~e these general objectives it is necessary to detect appro-
priate sources of potential fabric defects in the looms and set into motion
corresponding contol operations. Although it has been customary in the
art to detect, for example, certain types of defects for the purpose of
stopping the loom, these in general have been limited to detecting broken
filling, broken warp, or missing filling. The system of U. S. Patent
3j410, 316 issued to J. Giuttari on November 12, 1968 senses the
presence of a weft yarn mechanically in a shuttleless loom by means of a
mo~rable feeler arm. Many other filling or yarn processing sensors are
mechanical in nature and are not generally feasible for use in modern
high speed shuttleless looms. Accordingly, electronic weft or filling
~ensors have been developed which operate to determine in the course of
each pick period the presence of a pick.
Within the environment of air jet looms it has been convenient to
sense the condition (presence or absence) of each filling yarn as it
- egresses from the air containment tube. Typically the following patents
provide photo-electric sensors that may be located in the confusor
element exit slot to determine the passing of a filling yarn out of the con-
fusor; U. S. 4, 085, 777 issued to Z. Dadak et al, on April 24, 1978,
U.S. 4, 150, 699 issued to J. Suekane on April 24, 1979; U. S. 4, 1~3, 901
issued to J. Su~kane on February 19, 1980; and British Specification
28 1,236,346 oI E. Sick published Z3 June 1971.
6~7
Although these prior art sensors may be applicable for their in-
tended purpose, there are ce~tain types of critical yarn defect conditi~ns
in the wea~ring process that may not be discr;minated without improvement
in the ~ensing and control mechanisms.
Beyond the foregoing there are prior art system~ for weaving
machines to identify output quality and to decrease machine down time for
mechanical repairs as, for example, ~et forth in the ollowing documents:
U. S. Patent No. 3, 613, 743 issued to T. Sakamota on Octoberj 19,
1971 which applies an automatic fabric inspection apparatus to a loorll to
inspect and record the quality of fabric produced. This patent relates
~trictly a post-fabric formation inspection device.
U. S. Patent No. 4, 178, 969 issued to M. Gotoh et al. on December
18, 1979 which provides a system mode of operation which keeps weaving
machines with lower machine repair~ in operation awaiting off-line main-
tenance lmtil higher priority repairs are corrected.
U. S. Patent No. 4, 146, 061 i~sued to M. Gotoh on March 27, 1979
where index yarn or yarns are inserted to make fabric for identifying an
event such as an improperly inserted pick as an aid in inspection an~l
post-processing of the fabric.
None of the foregoing nor other known prior art predicts the quality
of the fabric at the point of fabric formation. Neither does the prior art
provide for operation of a loom in a greater output mode in response to a
favorable high quality operating condition. These objectives are achieved
by the present invention.
Z5 Summary of the Invention
In accordance with the present invention, novel sensors and in-
dicators are provided together with control systems and methods for prc-
28 diction and control of fabric output quality from a loom. With the
11~6~347
improved sensors, looms may be operated in response to predicted
qua]ity indicia or statistical~y calculated indices derived from a multiple
of signals sensed in the various portions of the loom. Additionally, an
increased output mode producing more fabric from a loom than heretofore
feasible can be employed while maintaining acceptable output quality.
More specifically, selvage edge defects not heretofore sensed in
loom control systems are discriminated by means of improved filling or
weft yarn detection means for sensing at critical positions of the filling
passing through the confusor tube. Such defects as a blown pick, short
pick, or selvage defects such as a jerk-in or folded over selvage end
filling yarn may be electronically detected at high speeds with considerable
accuracy and used for loom control as well as prediction of fabric quality.
Al~o, certain other loom conditions can lead to probable fabric quality
changes and thus are desirably processed to derive a fabric quality index.
Ln accordance with the present invention novel sensing means are
provided in a confusor element. A retroreflective photoelectrically in-
duced signal is processed by a randomly oriented bundle of optical fibers
to produce a reinforced signal distinguishaUe from noise. This retro-
reflecti~e technique provides a more advantageous signal than heretofore
available because a signal of longer duration i8 generated. Other more
conventional signals indicating defective warp or filling yarn conditions
are also employed to determine a fabric quality control index from a
variety of loom conditions that might cause a defect in the fabric output.
The detected signals are displayed, counted or statistically analyzed to
produce a quality control index. Typically the index predicts potential
defects in the fabric per unit length measure. A quality control index
prediction Or fabric quality is thus calculated as the fabric is formecl on
28 the loom, without examination of the produced fabric. The index, in
6~347
addition to precluding the need for manual post-inspecti~n of the fabric,
i8 also used as a control tri~ger for bypassing loom stopping when the
index i~ favorable.
Thus, with looms having a quality control index available schedllled
priorities of shutdown may be determined to keep looms in a mill running
with more output efficiency. With the provided information an operator
n~ay run more looms in a mill with higher running time eficiencies as a
result of this invention. For example, loom output efficiency is atta;ned
by manual or automatic control to eliminate machine shutdowns for rninor
defects which can be tolerated in the output fabric whenever the quality
control index is above predetermined acceptable quality threshholds.
Other features, advantages and objectives of the invention will be
fount throughout the following drawings, claims and more detailed des-
cription.
Brief Description of the Drawin~
Figure 1 i9 a perspective view of pertinent loom features illus-
trating the operational features of the present invention;
Figures 2A, 2B and 2C are respectively side, end and gap views
of an improved photoelectrlc sensing means afforded by this invention;
Figure 3 is a diagrammatic segmental view of the sensing means
illustrating detection of light reflection from a yarn passing the sensor
head;
Figure 4 is a timing waveform chart;
Figure 5 is a schematic block circuit diagram of a sensing circuit
arrangement embodying the invention;
Figure 6 is a block circuit diagram of a quality control syslem
embodying the invention; and
28 Figure 7 is a block circuit diagram of a simplified embc,{'in-~- lt
~ 6~347
illustrating pri~ciples of operation of this invention to monitor stop per-
formance of the loom in rela~ion to yards of fabric produced and allo-~ing
the filling defects to pa~s into fabric under preset condition~.
De~cri tion of Preferred ~nbodiment
,. P
With reference initially to Fig. 1 there is illustrated a loom L for
producing fabric 10 by inserting filling yarn lengths 11 or, simply "filling",
into the shed where warp yarns 12 are manipulated by the warp framework
or harnesses 14, 15. Thus, each Alling 11 i8 in~erted under proper
tension and forced again~t the preceding such filling yarn length in place
at the boundary or fell 13 of the wo~en fabric 10. The loom L illustrated
i~ a ~huttleles~ loom of the type more particularly ~hown and tescribed in
detail in commonly assigned Patent application
Serial No. 375,g92 of C.W. Brouwer, et al filed April 22, 1981.
In this loom an air ~ource is pulsed through a gun 16
at a time controlled by appropriate ignals from a timing means 18. Yarn
Zl, which is the source of each pick 11, is supplied from package 19
through fiiling yarn feed mechanism 17. A warp yarn feed mechanism
(t shown) supplies a continuous feed of warp yarns 12 at a speed con-
~iotent with the production of fabric 10. As each filling 11 is inserted is~
a timed relationship by gun 16 the filling is propelled through a confusor
tube 22 compri6ing a set of confusor elements 30. Each filling 11 is then
recei~red and held at the ~elvage end in a vacuum receptor 24, assuming
the pick i~ a normal pick moving in a normai path.
The propensity for error in a weaving operation as just described
is significant in the filling operation. For example, a filling 11 may not
reach the receptor 24, or the filling may be broken, folded, or otherwise
un6atisfactory. Also, other types of faults may occur which will distllrb
the quality of the output fabric 10. As previously stated, looms are
6 -
... , ..... ., ., ~ , . . .. . .
~1~6~47
con~entionally provided with sensors which stop the loo~ns for repairs
whe~n the weft or filling yarn is broken or when the pick is missing. Even
though the repairs are made the stopping and starting of the loom clisturbs
its rhyth~ and may cause the next inserted filling to be visibly diffcrent
from the rest of the woven fabric 10. Such defects result from improper
weft repair and loom starting techniques employed by operators of varied
~kill. Thus, each loom stop may affect the quality of the fabric.
Fabric is normally rated as first or second quality on the basis of
inspection of the fabric to determine how many faults per unit length are
present. These faults may be weighted in establishing a quality control
index such a~, for example, allocating ten points for a major fault and
one or two points for a minor fault. Statistically, specific reasons for
loom stoppage~ and subsequent fabric repair yield widely divergent
quantities of major faults. For instance, repairs of broken or missing
filling are far more frequently incorrectly repaired in comparison to
repair of broken warp ends. In large measure this i8 due to the necessity
of matching the proper shea sequence and pitch of filling yarns. Con-
sequently, a highes percentage of filling faults yield major fabric defects
than do warp repairs.
The present in~ention directly analyzes the loom performance to
provide its running quality control index by sensing various loom or yarn
feed conditions and counting them. The sensed conditions may be statis-
tically analyzed to predict or indicate a running rate of fau~t occurrences
per unit length of fabric in a probable quality control index. Such index
provides a criterion for either a monitor of fabric gra~e to identify first
or second grade fabric, or a control of the loom in order to achicvc
acceptable output quality with higher production efficiency.
28 This analysis requireq improvements in sensing loom concliticns,
~146~
particularly filling yarn conditions. In the present invention these in~prove-
ments include sensors 23 and 2 . Sensor 23 consists of an optical fiber
bundle 31 integrated within a confusor element 30 for the purpose of
detecting filling yarn as it egresses the confusor tube. Traditionally, in
the art of weft insertion, confusor element sensors have heretofore pro-
vided signals which are of extremely short duration due to the fact that
f;lling yarn egresses from the confusor tube at a very high speed and
prior art sensor geometry has been limited to very small sensor sizes.
In the present invention improvements in the signal system are achieved
by constructing the improved sensor 23 as shown in Figs. 2A-2C. Thus,
~ensor 23 includes the optical fiber bundle 31 which has a viewing face 32
bound by a steel band 33. Fiber bundle 31 joins at a suitable remote
location with a lamp 41A and a photoelectric cell 41B as seen in Fig. 2A,
The fiber optical bundle actually consists of two sets of fibers, identified
as fibers 36 and 37, respectively, in Fig. 2A. Fiber set 36 constitutes a
light transmitting set while fiber set 37 is a signal receiving set. As best
seen in Fig. 2A fiber sets 36 and 37 are joined to form the common fiber
bundle 31 which terminates in a sensor face 3Z. Viewing sensor face 32
in Fig. 2B it will be seen that fiber sets 36 and 37, actually consist of a
plurality of individual optical fibers 38 and 39, respectively. The plural-
ity of fibers 38 and 39 are interspersed with each other in random fashion,
that is to say, the fibers 3~ and 39 are uniformly distributed throughout
the 9ensor face 32, to thereby maximize the time of retroreflection of
light from the yarn as the yarn transverses the entire sensor face 32.
Thus, fiber set 37 transmits a light signal modulated by reflection 25
(Fig. 3) off the filling 11 and carried back by the fiber set 37 to th~ photo-
cell 41B. As best seen from Fig. 3, the gap 34 between opposin~ faces
28 of the confusor element 30 permits filling 11 to pas~ transversely arlcl
~146~47
depart alon~ gap pa1:hway 20. While filling 11 i9 in the ield of view of
the fiber optic bundle 31 light rays 40 are transmitted from fibers 38 in
set 36, and are received primarily within the face 35 of the confusor
element 30, which desirably is recessed and pro-~ided with a non-reflective
surface, preferably black, to increase the signal to noise ratio. Thus, a
significant part of the light rays 25 renected back into the fiber set 37 for
detection are those reflected off the filling 11 passing through the gap 34.
The individual fibers are preferably of a diameter approximating that of
the filling 11. Thus, as the filling 11 transverses the sensor face 32,
pickup sensor fibers 39 transport light reflected from the yarn to the
photoelectric cell 41 by means of the fiber set 37 containing the randomly
interspersed fibers 39 which collect light as the filling progresses across
the sensor face 32 producing a maximized signal change and duration.
Because of the multiplicity of randomly placed fibers, therefore, the
signal received will be sustained with a definite expected increase of re-
ceived light level over the time it takes for the filling li to travel aeross
the entire sensiDg face 32. In this manner flutter of the fiber is elimin-
ated as a significant actor in shape or duration of the signal. Typical
dimensions in the sensor include a fiber diameter in the order of . 001
inch (. 25 mm) and a diameter of the sensing face 32 in the order of .040
inch (10 mm). Sensor 23 is most conveniently used when fiber bundle 31
need only meet the confusor gap 34 on one face 32.
Distinct advantages of this detector 23 is its insensitivity to any
mis-positioning or flutter of the yarn, and production of a signal of
definite characteristics and duration distinguishable from random noise
impulses. Clearly, therefore, the improved sensor 23 provides a more
definite and improved signal. Sen~or 23 may be positioned in any of
28 several locations, or a plurality of sensors 23 may be disposed a~ a
47
variety of locations along the len~th of cDnfusor tube 22 It has b~cn
found ad~rantageous to place one sensor 23 near to but slightly inboard on
the right hand end of the fabric being woven (viewing Fig. 1) say, inboard
of the right hand selvage of the fabric about 2 inches. Sensor 23 and its
placement permits analysi~ of the status of a pick at the ~elvage end of
the filling.
Turning now to consideration of sensor 24, as best seen in Fig. 1
this sensor i6 located with vacuum receptor 25, This sensor 24 an '. its
mode of operation are more particularly set forth in the aforementioned
patent application Serial No. 375,992 of Charles W. Brouwer, et al.
Briefly, ~ensor 24 consi~t~ of an array of three light emitting diodes
oppooed by three photo-detector~ and serve~ to detect filling 11 as the
filling enters vacuussl receptor 25 when light is interrupted by the reception
of filling 11 therein.
The combination of ~ensor~ 23 and 24 are employed advantageo~sly
in the pre~ent invention in detecting filling failure modes heretofore un-
detectable. These ~ensors al~o 6erve the objective of improving lc~om
output and yarn quality as will be hereafter more ~pecifically described.
Normally, in routine operation of loom such as that shown in Fig.
2~) 1, filling 11 is con~reyed through the shed and depo~ited in vacuum receptor
25. Sensor 24 detects that latter event. However, condition~ occur where
filling 11 is not properly inserted and does not reach vacuurn receptor 25
nd, thus ~ensor 24. Thi~ can result when the pick is wrinkled, folded,
~hort, missing, or blown off. If these insertion error6 were allowed to
pass into the complcted fabric the location of these defects would have
tremendous variation in impact on fabric quality. For example, a pick
in~erted to within two inches of the right hand selvage is classified as a
28 minor fabric fault. This region is identified as a selvage border rl !:ion.
- 10 -
1146~
However, a pick inserted short by three inches or more is classified as a
major fabric fault. Typicall~, for a fabric grading syste~n allowing up to
40 quality points per 100 yards of fabric for first quality fabric, a minor
fault is assigned 1 point and a major fault 10 points. The locations o folds
or wrir~les along the inserted pick have similar impact on quality ratings.
Two additional improper insertions require further explanation.
False stops are picks properly inserted within the fabric body but which
did not get sucked into the vacuum receptor 25. In the mode where a single
sensor 24 i8 employed, the sensor 24 indicated a filling fault shutting down
the loom despite the fabric being without fault. This error wauld have no
impact on fabric quality. When such faults are detected in the manner
hereinafter shown improved loom output efficiency may occur by avoiding
shutdown for false stops.
Another improper insertion is unique to air jet looms and designated
as a blown off pick. In this instance, a variety of different machine or yarn
conditions may result in- the pick being severed during the process of in-
sertion and carried in its entirety into the receptor sensor 25. Despite the
positive signal from the receptor sensor 25 that the pick is in place, the
fact i8 that the pick is not present in its proper position in the shed. Con-
sequently, a major rabric fault results.
The critical placement of fiber optic sensor 23 in combination with
sensor 24 enables analysis of these potential errors and their location.
Thus, these detectors discriminate between errors of minor and major
fabric quality impact. TbLe following table tabulates insertion error con-
~itions, sensor 23 and 24 signals responsive to these insertion conditions
and .he impact of these errors on quality.
28
6~7
Dctectable Quality
Insertion Errors Sensor 23 Sensor 24 Irnpact
Faise Stop Yarn No YarnNone - (But imp~ct3
on output)
Wrinkled, Folded, or
Short Reaching Sensor
23 Yarn No YarnMinor
Wrinkled, Folded, No Yarn No YarnMajor
Missing, Short Not
Reaching Sensor Z3
Blown Off Pick No Yarn Yarn Major
From the foregoing table it is seen that not only can the preseni
invention sense loom conditions heretofore unachievable but also it is seen
that fabric quality impact between major and minor defects can readily be
discriminated and output loom efficiency can be improved. Sensor 23
always sees no yarn for an error of major magnitude.
In Fig. 4 To is a reference signal that i9 timed by the loom crank-
shaft rotation at a point in the cycle indicating timing synchronism with the
time when the yarn pick should ha~re been inserted and has been rernoved
from confusor tube 22. The relative timing of the signals at sensors 23,
24 is shown in Fig. 4. These signals are processed in the circuit of :~ig.
5 in a mode of operation afforded by this invention.
As seen in Fig. 4 flip flops 43, 44, 4S respectively, receive and
latch signal To and the signals from sensor 23 and sensor 24. Each flip
flop has two output positions, A and B, where A is normally low and B
normally high. On receipt of an input signal, outputs A and B reverse so
A is high aild B is low. Since a major fault has occurred when sensor 23
does not see yarn~ (i. e., pick 11 ha~ not reached sensor 23 the output B
of flip flop 44 remains high and is fed to AND gate 42. Also output A of
flip flop 43 is fed to AND gate 42 so that both inputs to AND gate 42 are
satisfied and produces an output signal to stop the loom. S;nce a rnillor
28 fault potentially has occurred when sensor 23 sees yarn but sensor 24
- 12 _
~46~147
does not see yarn (i. e., th~ pick does not reach vacuum receptor 25) out-
put A of nip flop 44, output B.of flip flop 45 and output A of flip flop 43 are
fed to AND gate 47 80 that all three inputs of AND gate 47 are high and a
signal i8 outputted from AND gate 47. This output signal i9 fed to AND
gate 46 as well as to counter 48. Counter 48 can be set to produce a con-
tinuous output after an adjustable preset count has been achieved. The
counter output is also fed to AND gate 46. Therefore, for any minor fault
signal emitting from AND gate 47 after the counter preset value has been
reached v,till satisfy both inputs to AND gate 46 so that a signal is outputted
from AND gate 46 to stop the loom and set an alarm to indicate excessive
minor faults. Until the preset count of counter 48 has been achieved,
minor faults do not act to shut down the loom. Flip flops 43, 44, 45 are
reset by feeding the output A of flip flop 43 through time delay 46 which, in
turn, output5 a signal upon completion of time delay to all resets R. This
delay, which is controlled by time delay 46, i8 determined to permit com-
pletion of all control functions prior to resetting. Counter 48 may be
periodically or otherwise reset.
The foregoing description iY a representative means for effecting
control of loom L whereby output efficiency of the loom is increased by
precluding loom stops whiie maintaining acceptable fabric quality output.
However, this invention advantageously provides for predicting fabric
quality with or without intervention into the loom to control its operation.
The circuit of Fig. 6 represents a simpliied quality control prediction
embodiment of the invention.
As previously stated, although the loom L i8 or can be stopp~d Eor
any type of fault, the manual repairs may not result in perfect fabric.
Common failures on fabric repair are defects, normally called "sct t-nark~"
Z8 where the Eilling pitch, thread to thread, displays a variation eithcr too
~1~6q:~7
close or too far apart. Statistically, all filling repairs necessitat~ Ih~
removal of a poorly inserte~ pick and the attendant adjustment to the
fabric advancing mechanism. This procedure results in a significantly
hig~ier percentage of major faults than does the repair of warp. This in-
vention monitors vasious stops and sensor data, predicts on the basis of
statistical impact, and decides on the basis of probable quality whether to
effect stopping of the loom for manual repair or to pass the defect into the
fabric while stil 1 maintaining acceptable fabric quality. The invention
also eliminates the need for complete manual inspection of the fabric by
identifying and displaying probable quality so that at the time of finished
fabric doffing the quality level can be recorded on the doffed fabric.
Referring to Fig. 6, pick counter 50 operates to produce an out-
put 8ignal when one yarn of fabric has been woven on loom L. An ad-
justable set count 49 is set into pick counter 50 which equals the number
of picks per yard of fabric woven. Upon achieving the preset count
counter 50 outputs a signal to yardage counter 51 and a simultaneous
signal through line 49A to reset pick counter 50 to zero. Yardage counter
51 accumulates and displays via panel S2 the total number of yards of
fabric woven since inception of the current weaving cycle.
ZO To determine the probable or predicted fabric quality, stop signals
of both the filling and warp type are detected for processing at input leads
54 and 55, respectively. Any conventional stop signal mechanism can be
employed to produce such signals. As described herein, a filling stop
signal is derived via AND gate 42 and fed to lead 54. The signal to input
lead 55 may be produced by the operation of a conventional warp drop
wire detector (not shown). Further, minor faults as indicated by a signal
output from AND gate 47 may be detected at lead 56. Additionally, other
28 loom system conditions that might affect fabric quality may be sens~ d at
- 14 -
1~46~47
lead 57. These might include yarn slubs, for example. Such a sll-b
condition could be detected by A conventional electronic slub detector 57A
-
(Fig, 1) connected into lead 57.
The weight of each condition in determining a quality index is
assigned by means such as switches 58 in this embodiment, which selec~
inputs to a counter-accumulator 59 for typically registering one, one-half
and two-tenths output points. The weight can be ~aried to justify a count
to any appropriate quality control index standard~ and, if desired) supple-
mental counters or dividers may be used. Thus, the register display 59A
will show accumulated quality points for all detected conditions. This in-
formation by itself i8 valuable in showing whether the quality is good or
bad, 80 that in accordance with this invention goods may be marked,
corrective actisn taken or production quantity improved.
For a running index rate conventionally used as a quality measure,
namely weighted faults or quality points per unit fabric length such as 100
yards, the accurnulated points on counter 59 are divided by the number of
hundreds of yards produced via lead 53 to division circuit 71 froIn which
the quality point (QP) index points per 100 yards is derived and displayed
on panel 72. A typical weighting for accumulating points in a system is
developed on the following table summarizing operation at the end of a
first 100 yards of fabric processed.
INPUT COUNT WEIGHT PROBABLE QP QP/100 YD.
.
Filling stops 12 1 12. 0
Warp stops 10 . 22. 0
Minors 6 . 53.0
Filling 4 1 4. 0
21.0 21.0
28 Thus, display 72 will show 21. 0 per hundred yards.
- 15 _
~146~1~7
Assuming that an acceptablc quality pOint index ~vere 40, tl~ any
count on display 72 greater than 40 could generate an alarm at lead 73.
Conversely, a low count such as 20 or below could provide on lead 7~L a
signal which would inhibit a minor fault stop of the loom at AND gate 46,
since the likelihood of obtaining second grade quality fabric would be slight.
Under these circumstances the circuit diagram in Fig. 5 would be alte~ed
80 that counter 48 would be replaced by input lead 74. Thus, the feature
provides more efficient output from the loom whenever quality conditions
are high. Other magnitudes could be used for making these control
decisions.
This invention therefore senses the loom operation, not the pro-
duced fabric, and may therefore predict the quality of the fabric being pro-
duced and provide a running index of fabric quality as it is being produced.
An alternative concept for increasing loom productivity is shown in
Fig. 7. This simplified, less expensive approach does not require
presence of sensor 23 foregoing the necessity of qualifying whether the
potential fabric defect is of major or minor impact.
Referring to Fig. 7, counter 90 counts the number of To signals
and, hence, the number of filling picks inserted. Further counter 90 can
be preset to an adjustable value at 91 and when this value is achieved will
output a signal at lead 92. This output signal is routed to the step up in-
put of a step up/step down counter 94. The output 92 of counter 90 is also
fed via lead 96 to a reset R on counter 90. Hence, counter 90 produces a
momentary output each time it reache~ its preset value. A typical value
for counter 90 is the picks produced in one hour of operation at 100"1"
efficiency. Such setting in counter 90 is a convenient reference for either
elapsed weaving time or, in the alternative, length of fabric woven.
28 Filling or warp stop commands 93 are fed to the step down input Or
- 16 -
~1~6~:347
step up/step down countcr 94. Step up/step do~vn counter 94 i5 arrangc:d
so that it will output a continuous signal whenever the counter value i5
zero or less than zero. Thus, this counter 94 is performing the f~mction
of monitoring loom performance. Whe~ using a set point value of one hour
of picks produced on the loom on counter 90 and when counter 94 has a
value above zero, the loom is operating at less than one stop per hour.
If counter 94 is zero or less, the loom is operating at a stop rate in e xcess
of one stop per hour. Both the outputs from counter 94 and the filli~g
stop command are fed to AND gate lO0. Hence, when the loom is running
at an acceptable level, counter 94 has no output and the filling stop
command, der*ed from sensor 24, is inhibited from stopping the loom.
If the loom is running at an unacceptable level, and consequently likely to
produce excessive fabric defects, there is an output from counter 94 which
allows stop commands derived from sensor 24 to stop the loom. Since
warp stop commands will continue to occur until the warp brea~ is
repaired, only the filling stop commànds are qualified at AND gate 100.
A time delay 102 is inserted in the path of stop commands and is in the
order of one loom cycle to allow proper operation of AND gate 102 before
stepping down counter 94. Obv~ously, the preset values of set point 91
and step up/step down counter 94 can be adjusted as desired.
From the foregoing it will be seen that the present invention ad-
vantageously provides means and method for sensing loom conditions
during the weaving cycle, analyzing the sensed conditions and controlling
loom operation in response thereto so as to allow a controlled number of
defects to be woven into the finished fabric but to stop the loom wllcll the
defects or faults e.~cceed a predetermined value. The is-vention furthcr
providet improved sensing meanq for weft yarn leaving an air con~aill-
28 ment tube, such sensing means providing a device for providing a si nal
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~146~347
indicative of certain of the faults which may occur during the weavln(~
cycle. By virtue of the features offered by the present invention loom out-
put efficiency is impro~ed by allowing a controlled number of faults to
enter the fabric being woven without stopping the loom.
It will be apparent that the present invention may be embodied in
other specific forms without departing from the spirit or es~ential attri-
butes thereof, all of which are intended to be encompassed by the
appended claims.
28
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