CA1146047A - Means and method for controlling the operation of a loom - Google Patents

Abstract

MEANS AND METHOD FOR CONTROLLING THE
OPERATION OF A LOOM
ABSTRACT OF THE DISCLOSURE
A weaving loom is equipped with conventional filling and wa??
sensors which operate in normal modes to stop the weaving operation when a fault is detected in either the filling or the warp. The present disclosure is directed to improvements in such a loom wherein loom stop signals are monitored in relation to amounts of fabric produced on the loom, or time of operation of the loom. When the loom is operating within predetermined limits of performance a filling defect is allowed to pass into the fabric without stopping the loom, thereby improving loom output efficiency.

Description

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 ... , ..... ., ., ~ , . . .. . .

~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 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.

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.

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 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 ~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 ~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.

Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. The method of operating a loom normally responsive to a loom stop signal to stop the loom including the steps of, monitoring the number of loom stop signals per unit length of fabric woven on the loom, providing a prescribed performance level value indicative of acceptable loom per-formance, comparing said number of loom stop signals to said prescribed performance level, and precluding stopping of the loom when said number of loom stop signals is less than said prescribed performance level.

2. The method according to claim 1 wherein the step of monitor-ing the number of loom stop signals is derived from sensing a defective filling yarn condition.

3. The method according to claim 1 wherein said loom is normal-ly responsive to either a defect in a warp yarn or a defect in a filling yarn to stop the loom, and including the step of stopping the loom on any signal resulting from a defect in warp yarn while stopping the loom only when the number of signals from defects in the filling yarn exceeds said pre-scribed performance level.

4. The method of operating a loom normally responsive to a loom stop signal to stop the loom including the steps of, monitoring the number of loom stop signals per unit length of loom operating time, providing a prescribed performance level value indicative of acceptable loom per-formance, comparing said number of loom stop signals to said pre-scribed performance level, and precluding stopping of the loom when said number of loom stop signals is less than said prescribed performance level,

5. The method according to claim 4 wherein the step of monitor-ing the number of loom stop-signals is derived from sensing a defective filling yarn condition.

6. The method according to claim 4 wherein said loom is normal-ly responsive to either a defect in a warp yarn or a defect in a filling yarn to stop the loom, and including the step of stopping the loom on any signal resulting from a defect in warp yarn while stopping the loom only when the number of signals from defects in the filling yarn exceeds said prescribed performance level.

7. Apparatus for operating a loom normally responsive to a loom stop signal to stop the loom including monitoring means for monitoring the number of loom stop signals per unit length of loom operating time, means providing a prescribed performance level value indicative of acceptable loom performance, comparator means for comparing said number of loom stops to said prescribed performance level, and means for precluding stopping of the loom when said number of loom stop signals is less than said prescribed performance level.

8. Apparatus as set forth in claim 7 wherein said means for monitoring the number of stop signals is operative to monitor defective filling yarn conditions.

9. Apparatus as set forth in claim 7 wherein said stop signals for halting the operation of the loom are derived either from a defect in a warp yarn or a defect in a filling yarn, and including means for stopping the loom on any signal resulting from a defect in the warp yarn while stopping the loom only when the number of signals from defects in the filling yarn exceeds said prescribed performance level.