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(11) | EP 1 460 158 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Filling bar preventing method and apparatus |
| (57) A filling bar preventing method starts a loom (10) after completing a preparatory
starting procedure including a cloth fell position correcting operation that corrects
the position of the cloth fell (22) by turning a surface roller (28) included in the
loom (10), and a warp tension adjusting operation that adjusts warp tension to a predetermined
warp tension by turning a warp beam (14) included in the loom (10). The preparatory
starting procedure is completed by completing the warp tension adjusting operation
after the completion of the cloth fell position correcting operation. |
Background of the Invention
Field of the Invention
[0001] The present invention relates to a filling bar preventing method and apparatus that perform a cloth fell position correcting operation for correcting the position of the cloth fell of a fabric on a loom, and a tension adjusting operation for adjusting warp tension.
Description of the Related Art
[0002] A filling bar preventing method disclosed in Patent Document 1 executes a filling bar preventing procedure before starting a loom for a normal weaving operation. The filling bar preventing procedure includes reversing the surface roller through a predetermined angle to shift the cloth fell backward, i.e., in the reverse direction opposite a direction in which warp yarns advance, turning a warp beam through a predetermined angle in the normal direction to adjust the tension of the warp yarns, and restarting the loom.
[Patent Document 1]
[0004] When trouble occurs in the loom in weaving operation, the loom is stopped, the cause of the trouble is eliminated, and then the loom is restarted. During repairing work for eliminating the causes of the trouble, the opposite ends of the warp yarns are cramped. If the trouble is caused by many causes, repairing work takes long time and hence the loom is stopped for a long stopping time. If the operator starts repair work a long time after the loom has been stopped or the cause of the trouble is difficult to repair, the loom is stopped for a long time. Thus, the stopping time for which the loom is kept stopped after the occurrence of trouble before restarting is dependent on various conditions.
[0005] For example, since the warp yarns are stretched by tension or their own weight, the warp tension decreases with stopping time. Therefore, the length of time necessary for a loom that carries out a warp tension adjusting operation for adjusting warp tension before restarting the loom to adjust warp tension is dependent on the change of warp tension during the stop of the loom.
[0006] A preparatory starting procedure to be performed before restarting the loom includes a cloth fell positioning operation that turns the warp beam and the associated guide rollers to move all the warp yarns to correct the position of the cloth fell relative to the beating-up position. The correction of the position of the cloth fell by the cloth fell positioning operation changes the warp tension.
[0007] Time necessary to complete the warp tension adjusting operation is dependent on the positional correction distance of the cloth fell, the change (reduction) of the warp tension which may occur while the loom is stopped.
[0008] The inventors of the present invention have found through studies that the effect of stop of the loom on the position of the cloth fell and the warp tension is dependent on a member driven for cloth fell adjustment, such as the surface roller or the warp beam. If the warp tension adjusting operation is completed before completing the cloth fell position correcting operation, values of the warp tension set by the warp tension adjusting operation are changed by the cloth fell position correcting operation.
[0009] Whereas the cloth fell position correcting operation can be achieved in a substantially fixed time, time necessary to complete the warp tension adjusting operation changes according to the change of the warp tension while the loom is stopped. Consequently, the time when the warp tension adjusting operation is completed is not definite with respect to the time when the cloth fell position correcting operation is completed. Thus, it is possible that actual warp tensions at the restart of the loom and at the first beating-up motion after the restart of the loom deviate greatly from desired warp tensions and, consequently, filling bars are formed.
[0010] Thus, the filling bars cannot necessarily be prevented simply by carrying out the cloth fell position correcting operation and the warp tension adjusting operation, and there have been problems in the reliability of the cloth fell position correcting operation and the warp tension adjusting operation in preventing filling bars.
[0011] Few members are disposed between the surface roller and the cloth fell, and the distance between the surface roller and the cloth fell is relatively short. Change in length of the fabric extending between the cloth fell and the surface roller is small as compared with that of the warp yarns extending between the cloth fell and the warp beam. Since the rotation of the surface roller is transmitted to the fabric directly, the effect of turning the surface roller on the positional adjustment of the cloth fell is significant, and the cloth fell can be accurately moved forward and backward by turning the surface roller.
[0012] Since the warp yarns are in sliding contact with mechanical parts including heddles, the reed and droppers, friction between the warp yarns and those mechanical parts obstructs the accurate transmission of the torque of the surface roller to the warp yarns. Consequently, the effect of the surface roller on warp tension adjustment is inferior to that of the warp beam for the same purpose.
[0013] The torque of the warp beam on which the warp yarns are wound can be surely transmitted to the warp yarns. Therefore, the relation between the torque of the warp beam and the tension of the warp yarns is definite and hence it is suitable to use the warp beam for warp tension adjustment.
[0014] However, mechanical parts including the heddle, the reed and droppers are arranged between the warp beam, and the cloth fell and those mechanical parts exert frictional resistance against the movement of the warp yarns. Consequently, the accurate transmission of a change in the warp tension caused by turning the warp beam to move the warp yarns to parts of the warp yarns in the vicinity of the cloth fell cannot be achieved due to the frictional resistance of those mechanical parts on the warp yarns, and the position of the cloth fell is changed by the warp tension adjustment using the warp beam. Thus, the warp beam is less suitable for the positional adjustment of the cloth fell than the surface roller.
[0015] It is understood from the foregoing facts that it is desirable to allot the cloth fell position correcting operation to the surface roller and to allot the warp tension adjusting operation to the warp beam, when both accurate cloth fell adjustment and accurate warp tension adjustment are necessary for preventing the formation of filling bars in a fabric. Moreover, it is inferred that it is effective to complete the warp tension adjusting operation after the completion of the cloth fell position correcting operation.
Summary of the Invention
[0016] Accordingly, it is an object of the present invention to prevent the formation of filling bars with reliability through the accurate adjustment of the position of the cloth fell and the warp tension on a loom that requires a cloth fell position correcting operation and a warp tension adjusting operation prior to starting.
[0017] According to one aspect of the present invention, a filling bar preventing method comprises the steps of executing a preparatory starting procedure including a cloth fell position correcting operation that corrects the position of the cloth fell to a predetermined position by turning a surface roller included in the loom, and a warp tension adjusting operation that adjusts warp tension to a predetermined warp tension by turning a warp beam included in the loom; and starting the loom after the completion of the preparatory starting procedure. In such a method, the preparatory starting procedure is completed by completing the warp tension adjusting operation after the completion of the cloth fell position correcting operation.
[0018] According to another aspect of the present invention, a filling bar preventing apparatus comprises: a cloth fell position correcting device that carries out a cloth fell position correcting operation for correcting position of a cloth fell in a fabric on a loom by rotating a surface roller included in the loom; a warp tension adjusting device that carries out a warp tension adjusting operation for adjusting warp tension to a predetermined warp tension by rotating a warp beam mounted on the loom; and a main controller that starts the loom after the completion of a preparatory starting procedure including the cloth fell position correcting operation and the warp tension adjusting operation. In such an apparatus, the main controller completes the preparatory starting procedure by completing the warp tension adjusting operation after the completion of the cloth fell position correcting operation.
[0019] It should be noted that interruption of the cloth fell position correcting operation and that of the warp tension adjusting operation due to trouble arisen during the cloth fell position correcting operation and the warp tension adjusting operation are not the completion of the cloth fell position correcting operation and that of the warp tension adjusting operation.
[0020] According to the present invention, the preparatory starting procedure is completed by completing the warp tension adjusting operation that operates the warp beam to adjust the warp tension to the predetermined warp tension after accurately correcting the position of the cloth fell so that the cloth fell is at a predetermined position by the cloth fell position correcting operation that operates the surface roller to correct the position of the cloth fell, and then the loom is started for the normal weaving operation. Thus, both the position of the cloth fell and the warp tension having the most significant influence on the formation of filling bars can be accurately adjusted to the desired position and the desired warp tension, respectively.
[0021] Thus, it is possible to prevent the great deviation of the adjusted warp tension from the desired warp tension immediately before the start of the loom and to prevent the resultant formation of filling bars resulting from the delay of ending the turning of the surface roller behind ending the turning of the warp beam due to the indefinite change of the warp tension during the stop of the loom, and from the inevitable execution of the cloth fell position correcting operation after the completion of the warp tension adjusting operation.
[0022] In the filling bar preventing method according to the present invention, the warp tension adjusting operation may be started after starting the cloth fell position correcting operation.
[0023] In the filling bar preventing method according to the present invention, the warp tension adjusting operation after the completion may be started of the cloth fell position correcting operation.
[0024] The filling bar preventing method according to the present invention may further comprise the steps of estimating operating times necessary for completing the cloth fell position correcting operation and the warp tension adjusting operation, determining a time difference between a time point where the cloth fell position correcting operation is started and that where the warp tension adjusting operation is started on the basis of the estimated operating times, and determining time points at which the warp tension adjusting operation are to be started, on the basis of the time difference.
[0025] In the filling bar preventing method according to the present invention, the time difference between the time points where the cloth fell position correcting operation and the warp tension adjusting operation are to be started, respectively, may be a fixed time difference or a time difference selected from predetermined time differences determined taking into consideration changes in the warp tension.
Brief Description of the Drawings
[0026] The above and other objects, features and advantages of the present invention will become more apparent form the following description made in connection with the accompanying drawings, in which:
Fig. 1 is a block diagram of a loom equipped with a filling bar preventing apparatus in a preferred embodiment according to the present invention;
Fig. 2 is a block diagram of a take-up controller included in the filling bar preventing apparatus shown in Fig. 1;
Fig. 3 is a block diagram of a let-off controller included in the filling bar preventing apparatus shown in Fig. 1;
Fig. 4 is a time chart of assistance in explaining the operation of the filling bar preventing apparatus shown in Fig. 1;
Fig. 5 is a block diagram of a filling bar preventing apparatus in a first modification of the filling bar preventing apparatus shown in Fig. 1;
Figs. 6(A) and 6(B) are graphs of assistance in explaining the operation of a speed correcting device included in the filling bar preventing apparatus shown in Fig. 5; and
Fig. 7 is a block diagram of a filling bar preventing apparatus in a second modification of the filling bar preventing apparatus shown in Fig. 1.
Description of the Preferred Embodiments
[0027] Referring to Fig. 1, warp yarns 12 unwound from a warp beam 14 mounted on a loom 10 extend via a back roller 16, plurality of heddle frames 18 and a reed 20 to a cloth fell 22. A fabric 24 woven by the loom 10 and extending from the cloth fell 22 is guided to a surface roller 28 by a guide roller 26, and is taken up by a cloth beam 32. A pair of press rollers 30 press the fabric 24 against the surface roller 28 to deliver the fabric 24 at a predetermined rate to the cloth beam 32.
[0028] The warp beam 14 is driven for rotation by a let-off motor 34 through a gear mechanism 36 including a reduction gear to release the warp yarns 12 to form a warp sheet. The amount of the warp yarns 12 wound on the warp beam 14 decreases gradually as the warp yarns 12 are released from the warp beam 14. A sensor 38 measures the diameter of the warp beam 14 and sends a diameter signal S1 representing a measured diameter of the warp beam 14 to a let-off controller 40. The rotating speed of the output shaft of the let-off motor 34 is measured by a tachometer generator 42. The tachometer generator 42 sends a let-off rotating speed signal S2 representing a measured let-off speed to the let-off controller 40.
[0029] An actual warp tension acting on the warp yarns 12 is measured by a warp tension sensor 44. The warp tension sensor 44 measures load on the back roller 16. The warp tension sensor 44 sends a warp tension signal S3 representing a warp tension actually acting on the warp yarns 12 to the let-off controller 40.
[0030] The heddle frames 18 are moved alternately upward and downward by a heddle frame operating mechanism 48 that converts the rotating motion of a main shaft 46 into the vertical motion of the heddle frames 18 to control the warp yarns 12 for shedding.
[0031] The reed 20 is moved back and forth by a slay drive mechanism 50 driven by the main shaft 46 to beat up a picked filling yarn 52 into the cloth fell 22.
[0032] The surface roller 28 is rotated by a gear mechanism 56 including a reduction gear driven by a take-up motor 54 to deliver the fabric 24 in cooperation with the press rollers 30 to the cloth beam 32.
[0033] The respective rotating angles representing the rotated angle of the main shaft 46 and the take-up motor 54 are measured by encoders 58 and 60, respectively. A main shaft rotating angle signal S4 and a take-up motor rotating angle signal S5 are given to a take-up controller 62. The main shaft rotating angle signal S4 is given also to the let-off controller 40.
[0034] The cloth beam 32 is connected to a take-up torque regulating mechanism 64 driven by the main shaft 46 by a friction coupling, not shown. The cloth beam 32 is driven for rotation such that the surface speed of the cloth beam 32 is slightly higher than the moving speed of the fabric 24 to exert a fixed take-up tension on the fabric 24.
[0035] The let-off controller 40 and the take-up controller 62 as components of a filling bar preventing apparatus incorporated into the loom 10 will be described with reference to Figs. 2 and 3, and the operation of the filling bar preventing apparatus will be described with reference to Fig. 4.
[0036] Referring to Fig. 2, the take-up controller 62 includes a synchronization control unit 66 for controlling the driving amount (i.e. rotation amount) of the output shaft of the take-up motor 54 while the loom 10 is in a normal weaving operation, and a cloth fell position control unit 68 for controlling the rotation amount of the output shaft of the take-up motor 54 to correct the position of the cloth fell 22 with respect to the moving direction of the warp yarns 12 during a preparatory starting procedure.
[0037] When an operator depresses a start button 72 on the loom 10, a start signal S0 is given to a main controller 70. Upon the reception of the start signal S0, the main controller 70 gives a start preparation signal S7 to a drive signal generator 76 and a command signal generator 78 to make the let-off controller 40 and the take-up controller 62 ready for the preparatory starting procedure. The main controller 70 gives an operation signal S6 to a signal selector 74 included in the let-off controller 40 shown in Fig. 3 after the completion of the preparatory starting procedure.
[0038] Data including weft density of fabric 24 to be used for calculating a basic speed for the take-up motor 54, and correction amounts for correcting the position of the cloth fell 22 to be used during the preparatory starting operation are stored beforehand in a cloth fell position correction data storage device 82.
[0039] Upon the reception of the start preparation signal S7, the drive signal generator 76 performs a cloth fell position correcting operation for a time t2 (Fig. 4(D)). The drive signal generator 76 converts a drive amount (rotation amount) for the take-up motor 54 into a pulse-like cloth fell position control signal S11 on the basis of the correction data stored in the cloth fell position correction data storage device 82 during the cloth fell position correcting operation, and applies the cloth fell position control signal S11 to one of the input terminals of an adder 86 included in the synchronization control unit 66.
[0040] The synchronization control unit 66 includes a basic rotation amount signal generator 84 that calculates a basic speed for the take-up motor 54 on the basis of the weft density stored in the cloth fell position correction data storage device 82 and the main shaft rotating angle signal S4, and drives the take-up motor 54.
[0041] The basic rotation amount signal generator 84 generates a pulse-like basic rotation amount signal S10 for driving the take-up motor 54 for operation at a rotating speed corresponding to the basic rotating speed of the main shaft 46 while the loom 10 is in the normal weaving operation. Consequently, the take-up motor 54 is rotated into at a rotation amount corresponding to the rotation amount of the main shaft 46 of the loom 10.
[0042] More concretely, the basic rotation amount signal generator 84 generates the pulse-like basic rotation amount signal S10 representing the basic rotating speed of the take-up motor 54 on the basis of the received main shaft rotating angle signal S4 and the data on the weft density and such, and applies the pulse-like basic rotation amount signal S10 to the other input of the adder 86 while the loom 10 is in the normal weaving operation.
[0043] The adder 86 produces a pulse-like take-up target value signal S12 on the basis of the cloth fell position control signal S11 and the pulse-like basic rotation amount signal S10 applied to the two input terminals thereof, and gives the desired pulse-like take-up target value signal S12 to the addition terminal of an up-down counter 88.
[0044] The loom 10 is not in the normal weaving operation and the main shaft 46 is stopped in a start preparation period. In the start preparation period, the basic rotation amount signal generator 84 does not give the basic rotation amount signal S10 to the adder 86. Therefore, the adder 86 gives only the cloth fell position control signal S11 as the desired pulse-like take-up target value signal S12 to the up-down counter 88.
[0045] The up-down counter 88 counts the pulses of the cloth fell position control signal S11 input from the adder 86, and subtracts the take-up motor rotating angle signal S5, i.e., a pulse signal, provided by the encoder 60 combined with the output shaft of the take-up motor 54 from the counted number of pulses of the pulse-like cloth fell position control signal S11. The up-down counter 88 gives a take-up roller drive signal S13 to a take-up motor driver 90.
[0046] The take-up motor driver 90 is an amplifier that produces a drive signal by amplifying the input signal. The take-up motor driver 90 drives the output shaft of the take-up motor 54 for normal rotation when a take-up motor drive signal S13 received from the up-down counter 88 is positive or for reverse rotation when the take-up motor drive signal S13 is negative. Thus, the position of the cloth fell 22 of the fabric 24 is adjusted to a predetermined position.
[0047] The up-down counter 88 gives the take-up motor drive signal S13 proportional to the difference between the pulse-like take-up target value signal S12 and the take-up motor rotating angle signal S5 through the take-up motor driver 90 to the take-up motor 54. Thus, the up-down counter 88, the take-up motor driver 90 and the encoder 60 constitute a direct-coupled feedback circuit I including only proportional elements for controlling the take-up motor 54. Consequently, when the take-up target value signal S12 is different from the take-up motor rotating angle signal S5, the take-up motor 54 is driven so as to reduce the difference between the take-up target value signal S12 and the take-up motor rotating angle signal S5 to zero.
[0048] For example, the take-up motor 54 is a servomotor, and the direct-coupled feedback circuit I is a generally known circuit capable of controlling the servomotor.
[0049] Upon the reception of the start preparation signal S7, the command signal generator 78 gives a starting warp tension control start signal S9 on the basis of a start delay time signal S8 set by a setting device 80 to the signal selector 74 shown in Fig. 3 after a predetermined time t1 as shown in Fig. 4(E).
[0050] Referring to Fig. 3, the let-off controller 40 includes an operation control unit 94 provided with a control device 96, and a starting operation control unit 98 provided with a control device 100. A warp tension signal S3 provided by the warp tension sensor 44 is given to both the respective control devices 96 and 100 of the operation control unit 94 and the starting operation control unit 98. The operation control unit 94 includes a basic speed signal generator 102 that receives the weft density signal and the main shaft rotating angle signal S4 representing the rotating speed of the main shaft 46.
[0051] The basic speed signal generator 102 is similar in configuration and actions to the basic rotation amount signal generator 84 of the take-up controller 62. The basic speed signal generator 102 applies a speed signal S14 corresponding to the basic speed to one of the input terminals of an adder 104. The control devices 96 and 100 receive desired warp tensions T1 and T2 from warp tension setting devices 106 and 108, respectively.
[0052] The control device 96 calculates the warp tension difference between an actual warp tension measured by the warp tension sensor 44 and a desired warp tension (tension target value) T1 set by the warp tension setting device 106, converts the calculated warp tension difference into a speed correction signal S15 representing a rotating speed correction value by PID controller or the like, and supplies the speed correction signal S15 to the other input terminal of the adder 104.
[0053] The adder 104 adds up the speed signal S14 and the speed correction signal S15 to produce a normal operation speed signal S16, and supplies the same to one of the input terminals of the signal selector 74.
[0054] The control device 100 calculates the warp tension difference between the actual warp tension measured by the warp tension sensor 44 and the desired warp tension T1 set by the warp tension setting device 108, converts the calculated warp tension difference into a starting speed signal S17 corresponding to the warp tension difference by a gain controller or the like, and supplies the starting speed signal S17 to the other input terminal of the signal selector 74.
[0055] The signal selector 74 selects either the normal operation speed signal S16 or the starting speed signal S17 on the basis of the operation signal S6 or the starting warp tension control start command signal S9, and gives a speed signal S18, i.e., either the signal S16 or the signal S17, to a diameter correcting device 110.
[0056] The command signal generator 78 gives a starting warp tension control start signal S9 to the signal selector 74 after the time t1 has elapsed since the depression of the start button 72 (Fig. 4(C)). Upon the reception of the starting warp tension control start signal S9, the signal selector 74 selects the starting operation control unit 98 to give the speed signal S18 as the starting speed signal S17 to the diameter correction device 110.
[0057] The speed signal S18 provided by the signal selector 74 corresponds to a let-off speed at which the warp yarns 12 are released from the warp beam 14 in either of a starting operation state and a normal operation state. The diameter of the warp beam 14 decreases gradually as the warp yarns 12 are released from the warp beam 14. Therefore, the rotating speed of the warp beam 14 must be corrected according to the diameter of the warp beam 14 to release the warp yarn 12 at a fixed warp yarn feed rate. The speed signal S18 provided by the speed selector 74 is corrected on the basis of a diameter signal S1 representing the current diameter of the warp beam 14 measured by the sensor 38.
[0058] The diameter correcting device 110 corrects the speed signal S18 provided by the signal selector 74 on the basis of the diameter signal S1 provided by the sensor 38 to produce a corrected signal S19, and gives the corrected signal S19 to one of the input terminals of a subtractor 112.
[0059] In the let-off controller 40, signal selector 74 keeps selecting the control device 100 only for a time t3 (Fig. 4(E)) to operate the let-off motor 34 for warp tension adjustment. The time t3 is dependent on the deviation of the warp tension and the gains of the control devices. Different times t3 for different warp tensions are determined empirically beforehand.
[0060] The warp tension adjusting operation adjusts the actual warp tension of the warp yarns 12 to a desired warp tension T2 set by the warp tension setting devise 108 even if the cloth fell position correcting operation is in progress.
[0061] The rotating speed of the output shaft of the let-off motor 34 is measured by the tachometer generator 42 combined with the output shaft. The tachometer generator 42 applies the let-off rotating speed signal S2 representing the rotating speed of the output shaft of the let-off motor 34 to the other input terminal of the subtractor 112.
[0062] The subtractor 112 subtracts the let-off rotating speed signal S2 from the selected speed signal S18, giving a signal representing the result of subtraction to a let-off motor driver 114 to drive the let-off motor 34. Thus, the let-off controller 40 acts as a one component of a feedback circuit II that controls the let-off motor 34 so that the moving speed of the warp yarns 12 released from the warp beam 14 coincides with that represented by the corrected signal S19.
[0063] Referring to Fig. 4, the times t1, t2 and t3 are stored beforehand respectively in the main controller 70, the cloth fell position correction data storage device 82 and a setting device 80 so that the warp tension adjusting operation is completed after the completion of the cloth fell position correcting operation. The times t1, t2 and t3 are decide to meet an inequality: t2 < t1 + t3. Therefore, the times t2 and t3 overlap each other for a time t4. The time t4 is equal to a time between a time point where the time t1 from the depression of the start button 72 terminates, and a time point where the time t2 from the depression of the start button 72 terminates. Consequently, the loom 10 is able to achieve both the correction of the position of the cloth fell 22 and the adjustment of the warp tension.
[0064] Preferably, the relation between the times t3 and t1 corresponding to warp tension deviation is stored in a database, a time t1 corresponding to a measured warp tension deviation is read from the setting device 80 immediately before starting the preparatory starting procedure of the loom 10, and then operations are started.
[0065] Correction of the position of the cloth fell 22 is hardly affected by the warp tension adjusting operation and can be achieved by the cloth fell position correcting operation even if the cloth fell position correcting operation and the warp tension adjusting operation are performed simultaneously.
[0066] More specifically, components of the loom 10 including the heddle frames 18, the reed 20, droppers, the droppers the heddles and such are arranged between the warp beam 14 and the cloth fell 22 as mentioned above, and those components exert frictional resistance on the warp yarns 12. When the warp beam 14 is turned to let off the warp yarns 12, the warp yarns 12 are restrained from advancement by the frictional resistance of those component members and, consequently, the cloth fell 22 moves scarcely in directions parallel to the warp yarns 12.
[0067] Since any members are not interposed between the cloth fell 22 and the surface roller 28, and the cloth fell 22 and the surface roller 28 are spaced a short distance apart, the fabric 24 can be surely moved lengthwise according to the rotation of the surface roller 28. Thus, the position of the cloth fell 22 can be surely changed lengthwise by turning the surface roller 28 for the cloth fell position correcting operation, and thereby formation of filling bars can be prevented with reliability.
[0068] Whereas the cloth fell position adjusting operation is terminated upon the elapse of the time t2 after the depression of the start button 72, the warp tension adjusting operation is still continued. However, the position of the cloth fell 22 is changed scarcely by the warp tension adjusting operation.
[0069] More specifically, components of the loom 10 including the heddles the heddle frames 18, the reed 20, the heddles, droppers and such are arranged between the warp beam 14 and the cloth fell 21 as mentioned above, and those components exert frictional resistance on the warp yarns 12. Therefore, even if the warp beam 14 turned to move the warp yarns 12 lengthwise, the warp yarn moving motion of the warp beam 14 can be hardly accurately move the warp yarns 12 due to the frictional resistance exerted on the warp yarns 12 by the heddle frames 18, the reed 20 and such. Consequently, the cloth fell 22 is moved scarcely by the warp tension adjusting operation, and thereby formation of filling bars can be prevented with reliability.
[0070] Since the torque of the warp beam 14 is transmitted surely to the warp yarns 12 extending from the warp beam 14, the relation between the torque of the warp beam 14 and the tension of the warp yarns 12 is definite, which is convenient for warp tension adjustment.
[0071] The warp tension adjusting operation is terminated upon the elapse of the time t3. Thus, both the cloth fell position correcting operation and the warp tension adjusting operation are completed for the present.
[0072] Then, the main controller 70 gives the operation signal S6 to the signal selector 74 to start the loom 10 for the normal weaving operation.
[0073] Referring to Fig. 3, upon the reception of the operation signal S6, the signal selector 74 selects the operation control unit 94 to send the normal operation speed signal S16 as the speed signal S18 to the diameter correcting device 110.
[0074] As mentioned above, the control device 96 calculates the warp tension difference between an actual warp tension measured by the warp tension sensor 44, and the desired warp tension T1 set by the warp tension setting device 106, converts the calculated warp tension difference T1 into a speed correction signal S15, and applies the speed correction signal S15 to one of the input terminals of the adder 104.
[0075] While the loom 10 is in the normal weaving operation, the basic rotation amount signal generator 84 and the basic speed signal generator 102 calculate the basic rotation amount signal S10 corresponding to the advancing speed of the fabric 24 and the speed signal S14 corresponding to the basic speed, respectively, on the basis of the received main shaft rotating angle signal S4 and the data on the weft density and such, and supply the basic rotation amount signal S10 to one of the input terminals of the adder 86, and the speed signal S14 to one of the input terminals of the adder 104, respectively.
[0076] Since the cloth fell position correcting operation has been completed, the drive signal generator 76 does not give the cloth fell position control signal S11 to the adder 86.
[0077] Although the cloth fell position correcting operation has been described on an assumption that the cloth fell position correcting operation is started before starting the warp tension adjusting operation and ended after the warp tension adjusting operation has been started, the warp tension adjusting operation may be started after the completion of the cloth fell position correcting operation. In such a case, the take-up controller 62 may give a cloth fell position correction completion signal to the let-off controller 40 to start the warp tension adjusting operation.
[0078] Although the filling bar preventing method in this embodiment starts the warp tension adjusting operation after the elapse of the time t1 since the start of the cloth fell position correcting operation, the time t1 may be shortened or the time t1 may be reduced to zero to start the cloth fell position correcting operation and the warp tension adjusting operation simultaneously if the time t3 for the warp tension adjusting operation is far longer than the time t2 for the cloth fell position correcting operation.
[0079] The following modifications of the filling bar preventing apparatus are possible. It is possible that time necessary for completing the warp tension adjusting operation changes according to the reduction of the warp tension with time while the loom is stopped. Any problem will hardly arise if the loom is stopped for a long time. The warp tension adjusting operation needs a short time if the cause that stopped the loom is eliminated quickly before the warp tension decreases significantly; that is, if the cause is eliminated quickly, the completion of the cloth fell position correcting operation delays behind the completion of the warp tension adjusting operation, and problems encountered by prior art arise. Therefore, it is desirable to extend the time t1 to complete the warp tension adjusting operation after the completion of the cloth fell position correcting operation, when the deviation of the warp tension immediately before the start of the preparatory starting operation is small. Preferably, a warp tension deviation signal is given to the setting device 80 shown in Fig. 2, a plurality of times t1 are set for different warp tension deviations, and a time t1 corresponding to a measured warp tension deviation is selected when the start preparation signal S7 is generated.
[0080] Referring to Fig. 5 showing a filling bar preventing apparatus in a first modification, a let-off controller 40 and a take-up controller 62 change a cloth fell position control signal S11 for the cloth fell correcting operation according to a measured warp tension to adjust time necessary for completing the cloth fell position correcting operation.
[0081] More specifically, a starting operation control unit 98 included in the let-off controller 40 gives a signal representing the tension difference ΔT between a tension T2 set by a warp tension setting device 108, and a measured tension represented by a warp tension signal S3 provided by a warp tension sensor 44 to a control device 100 and a speed correcting device 116.
[0082] The speed correcting device 116 gives a speed command signal S20 representing a value of a coefficient K corresponding to the tension difference ΔT and greater than 1 to quicken the cloth fell position correcting operation to the drive signal generator 76. A table showing the relation between the values of the tension difference ΔT and the values of K may be empirically prepared beforehand, or the relation between the tension difference ΔT and the coefficient K may be formulated. In such a case, the time t3 for the warp tension adjusting operation is fixed.
[0083] A drive signal generator 76 receives a speed command signal S20, multiplies a value read from a cloth fell position correction data storage device 82 by K to produce a cloth fell position control signal S11, and gives the cloth fell position control signal S11 to an adder 86. This cloth fell position control signal S11 is greater than the cloth fell position control signal S11 generated by the drive signal generator 76 shown in Fig. 2. Thus, the surface roller 28 is rotated for the cloth fell position correcting operation at a rotating speed higher than that at which the surface roller 28 is rotated for the ordinary cloth fell position correcting operation to reduce the time necessary for completing the cloth fell position correcting operation. Thus, the cloth fell position correcting operation can be completed before the completion of the warp tension adjusting operation.
[0084] In Fig. 6, time is measured on the horizontal axis, and take-up speed corresponding to the cloth fell position control signal S11 provided by the drive signal generator 76 is measured on the vertical axis. The area of a shaded area is equal to a moved distance by which the cloth fell 22 is moved, i.e., a correction value by which the position of the cloth fell 22 is changed.
[0085] It is known from Figs. 6(A) and 6(B) that the time t2 required by the cloth fell position correcting operation decreases when the take-up speed is increased. Thus, the time point where the warp tension adjusting operation is completed can be apparently delayed owing to the reduction of the time necessary for the cloth fell position correcting operation.
[0086] Referring to Fig. 7 showing a filling bar preventing apparatus in a second modification, a let-off controller 40 and a take-up controller 62 change a starting speed signal S17 for the warp tension adjusting operation on the basis of cloth fell position correction value set by the cloth fell position correction data storage device 82 to adjust the time necessary for completing the warp tension adjusting operation.
[0087] When the cloth fell position correction value is large, the value of the starting speed signal S17 for the warp tension adjusting operation is decreased to increase the time necessary for the warp tension adjusting operation apparently. Consequently, the time point where the warp tension adjusting operation is completed is delayed.
[0088] More concretely, if the time t2 for the cloth fell correcting operation is unrelated with the set correction value for correcting the position of the cloth fell, i.e., if the time t2 is fixed, the value of a gain signal S21 provided by a gain correcting device 118 included in a controller 100 that operates at the start is decreased.
[0089] The filling bar preventing apparatus shown in Fig. 7 may determine the time t3 for the warp tension adjusting operation, and may change the gain signal S21 for the warp tension adjusting operation or the speed command signal S20 for the cloth fell position correcting operation on the basis of the relation between the times t2 and t3 to end the warp tension adjusting operation after the completion of the cloth fell position correcting operation.
[0090] More specifically, the take-up controller 62 sends a value stored in the cloth fell position correction data storage device 82 to the gain correcting device 118. The gain correcting device 118 sends a gain signal S21 representing a coefficient K2 of a positive value not greater than 1 and corresponding to the value stored in the cloth fell position correction data storage device 82 to a control device 100.
[0091] Upon the reception of the gain signal S21, the control device 100 calculates the warp tension difference between a warp tension set by the warp tension setting device 108 and a warp tension represented by a warp tension signal S3, multiplies the calculated warp tension difference by the coefficient K2 to provide a starting speed signal S17. A starting speed represented by this starting speed signal S17 is lower than that represented by the starting speed signal S17 provided by the control device 100 shown in Fig. 3. Consequently, the warp beam 14 is rotated at a rotating speed lower than that at which the warp beam 14 is rotated for the ordinary warp tension adjusting operation to extend the time required by the warp tension adjusting operation so that the cloth fell position correcting operation is completed apparently at an earlier time point.
[0092] In the cases shown in Figs. 6 and 7, the speed correction value and the gain are changed when the cloth fell position correction value is large. However, the present invention permits the following modifications.
[0093] For example, it is possible that time necessary for completing the warp tension adjusting operation changes according to the reduction of the warp tension with time while the loom is stopped. Any problem will hardly arise if the loom is stopped for a long time. The warp tension adjusting operation needs a short time if the cause that stopped the loom is eliminated quickly before the warp tension decreases significantly; that is, if the cause is eliminated quickly, the completion of the cloth fell position correcting operation delays behind the completion of the warp tension adjusting operation, and problems encountered by prior art arise.
[0094] Therefore, it is desirable to execute speed correction so that the speed of cloth fell position correcting operation decreases or to decrease the gain of the gain correcting device so that the rotating speed of the warp beam 14 decreases in order that the warp tension adjusting operation is completed after the completion of the cloth fell position correcting operation, when the deviation of the warp tension immediately before the start of the preparatory starting operation is small. Preferably, a warp tension deviation signal is given to the speed correcting device and the gain correcting device shown in Figs. 6 and 7, a plurality of values of the correction coefficient and a plurality of values of the gain are set for warp tension deviations and values of the correction coefficient and the gains corresponding to a measured warp tension deviation are selected when the start preparation signal S7 is generated.
[0095] It is also possible to estimate the respective operating times of the cloth fell position correcting operation and the warp tension adjusting operation to determine a time interval between the start of the cloth fell position correcting operation and the warp tension adjusting operation, and the cloth fell position correcting operation and the warp tension adjusting operation are started on the basis of the time interval.
[0096] The time interval between the start of the cloth fell position correcting operation and that of the warp tension adjusting operation may be a fixed value or a value selected taking into considerations factors that affect the warp tension from values set beforehand. For example the factors that affect the warp tension include time for which the loom 10 is stopped, set warp tension, distances by which the heddles are raised and lowered for shedding, and such. The crank angle of the main shaft 46 relates with distances by which the heddles are raised and lowered.
[0097] The time necessary for completing the cloth fell position correcting operation may be shortened by rotating the surface roller 28 at a rotating speed higher than that at which the surface roller 28 is rotated while the case of usual filling bar preventing method.
[0098] The time necessary for completing the warp tension adjusting operation may be prolonged by rotating the warp beam 14 at a rotating speed lower than that at which the warp beam 14 is rotated while the case of usual filling bar preventing method.
[0099] The difference between the rotating speed of the surface roller 28 during the cloth fell position correcting operation and that of the same while the case of usual filling bar preventing method may be a fixed value or may be a value selected according to the value of the factor that affect the warp tension from values set beforehand.
[0100] The surface roller 28 may be turned in the normal direction or the reverse direction during the preparatory starting operation. More concretely, the cloth fell position correcting operation does not need to be performed only once during the preparatory starting operation and may be performed twice during the preparatory starting operation. When the cloth fell position correcting operation is performed twice, the surface roller 28 may be turned in the same direction for the first and the second cycle of the cloth fell position correcting operation or may be tuned in opposite directions respectively for the first and the second cycle of the cloth fell position correcting operation.
[0101] The warp tension adjusting operation may be performed every time the cloth fell position correcting operation is performed or may be performed in combination with the last cycle of the cloth fell position correcting operation. The cloth fell position correcting operation may be performed three or more times.
[0102] Although the filling bar preventing apparatus estimates the warp tension from the measured load on the back roller 16 measured by the warp tension sensor 44, the warp tension may be estimated from the measured tensions of some of the warp yarns 12.
[0103] The warp tension sensor 44 that measures the load on the back roller 16 may be such as capable of measuring the strain or displacement of the back roller 16.
[0104] Although the warp tension sensor 44 is combined with the back roller 16 to measure the load on the back roller 16 in the foregoing embodiment, the warp tension sensor 44 may be combined with any member that is in contact with the warp yarns 12 or the fabric 24.
[0105] Although the loom shown in Figs. 1 to 4 controls the surface roller 28 and the warp beam 14 individually by the separate control circuits, the surface roller 28 and the warp beam 14 may be controlled by a single control circuit.
[0106] The signal generators 76,78 and 84, the control devices 96 and 100, the diameter correcting device 110, the feedback circuits I and II may be either pieces of hardware or software usable on a microcomputer.
[0107] The present invention is applicable to a loom that weaves fancy fabrics. For example, when the filling bar preventing apparatus is applied to a loom capable of selectively changing weft density by changing the number of picks per unit length of a fabric, the amount of the cloth fell position correcting operation at the start of the loom is selectively determined according to a weft density at the start of the loom. When the filling bar preventing apparatus is applied to a loom that changes a desired warp tension according to a change in weft density, a desired warp tension corresponding to a weft density at the start of the loom is determined at the start of the loom.
[0108] Although the control device 96 is supposed to perform the PID controller in the foregoing description, the control device 96 may be a generally known simple controller that performs a control action simpler than the PID controller. The simple controller may comprise a comparator that compares a measured warp tension with a set warp tension, and a speed command signal generating circuit that generates a speed command signal on the basis of the result of comparison made by the comparator. The simple controller may provide a speed command signal specifying a low speed to reduce the tension deviation and may stop the speed command signal upon the coincidence of the measured warp tension with the set warp tension.
1. A filling bar preventing method comprising the steps of:
executing a preparatory starting procedure including a cloth fell position correcting operation that corrects the position of the cloth fell (22) to a predetermined position by turning a surface roller (28) included in the loom (10), and a warp tension adjusting operation that adjusts warp tension to a predetermined warp tension by turning a warp beam (14) included in the loom (10); and
starting the loom (10) after the completion of the preparatory starting procedure;
wherein the preparatory starting procedure is completed by completing the warp tension adjusting operation after the completion of the cloth fell position correcting operation.2. The filling bar preventing method according to claim 1, wherein the warp tension adjusting
operation is started after starting the cloth fell position correcting operation.
3. The filling bar preventing method according to claim 2, wherein the warp tension adjusting
operation is started after the completion of the cloth fell position correcting operation.
4. The filling bar preventing method according to claim 2, further comprising the steps
of estimating operating times necessary for completing the cloth fell position correcting
operation and the warp tension adjusting operation, determining a time difference
between a time point where the cloth fell position correcting operation is started
and that where the warp tension adjusting operation is started on the basis of the
estimated operating times, and determining time points at which the warp tension adjusting
operation are to be started, on the basis of the time difference.
5. The filling bar preventing method according to claim 4, wherein the time difference
between the time points where the cloth fell position correcting operation and the
warp tension adjusting operation are to be started, respectively, is a fixed time
difference or a time difference selected from predetermined time differences determined
taking into consideration changes in the warp tension.
6. A filling bar preventing apparatus comprising:
a cloth fell position correcting device (68) that carries out a cloth fell position correcting operation for correcting position of a cloth fell (22) in a fabric on a loom (10) by rotating a surface roller (28) included in the loom (10);
a warp tension adjusting device (64) that carries out a warp tension adjusting operation for adjusting warp tension to a predetermined warp tension by rotating a warp beam (14) mounted on the loom (10); and
a main controller (70) that starts the loom (10) after the completion of a preparatory starting procedure including the cloth fell position correcting operation and the warp tension adjusting operation;
wherein the main controller (70) completes the preparatory starting procedure by completing the warp tension adjusting operation after the completion of the cloth fell (22) position correcting operation.