Weft pullback control method

Abstract

 A weft pullback control method controls a weft pullback device (4) included in a fluid-jet loom (1) having a weft storage device (2) for storing a length of a weft (5) unwound from a yarn package (6), and a picking nozzle (3), and disposed between the weft storage device(2) and the picking nozzle (3) to pull back a leading end part of the weft (5) extending between the weft storage device (2) and the picking nozzle (3) after the completion of a picking operation. The weft pullback control method makes the weft pullback device (4) pull back the weft (5) by a length greater than that by which the weft (5) is pulled back while the fluid-jet loom (1) is in operation, at least in a particular period in a period between the stoppage of the fluid-jet loom (1) and the start of the first picking operation after the restart of the fluid-jet loom (1).

Description

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] The present invention relates to a weft pullback control method of controlling a weft pullback device disposed between a weft storage device for storing a weft unwound from a yarn package and a picking nozzle to pull back the weft delivered from the picking nozzle.

Description of the Related Art

[0002] A fluid-jet loom disclosed in JP-U No. 79778/1994 is provided with a weft pullback device disposed between a weft storage device and a picking nozzle. The weft pullback device is provided with fixed yarn guides and a movable yarn guide that operate cooperatively to pull back a weft by bending a part, extending between the weft storage device and the picking nozzle, of the weft after the completion of a picking operation so that the weft may not extend excessively from the tip of the picking nozzle toward a fabric on the fluid-jet loom and the next picking operation may be stabilized.

[0003] A weft pullback operation is continued not only while the fluid-jet loom is in operation, but also while the fluid-jet loom is stopped. When a weft having a large unit weight, such as a glass yarn, is picked, the weft forms a large balloon between the weft storage device and the picking nozzle as shown in Fig. 1, and the next picking operation is started before the balloon of the weft disappears completely even if the weft is pulled back after the preceding picking operation because a high centrifugal force acts on the balloon. The balloon disappears completely when the fluid-jet loom is stopped. In this state, a part of the weft extending between the weft storage device and the picking nozzle slackens and hence the weft is pulled in a picking direction by a slight force exerted thereon by a fluid being jetted through the picking nozzle. Consequently, a long leading end part of the weft droops from the tip of the picking nozzle as shown in Fig. 2. The drooping long leading end part of the weft is liable to enter a shed during a setting operation before restarting the fluid-jet loom and to be woven into the fabric or to be entwined with warps to form a defect in the fabric.

SUMMARY OF THE INVENTION

[0004] Accordingly, it is an object of the present invention to provide a weft pullback control method capable of controlling a weft pullback device included in a fluid-jet loom so that an excessively long leading end part of a weft may not extend from the tip of a picking nozzle while the fluid-jet loom is stopped and in a period between successive picking operations.

[0005] According to one aspect of the present invention, a weft pullback control method of controlling a weft pullback device included in a fluid-jet loom having a weft storage device for storing a length of a weft unwound from a yarn package, and a picking nozzle, disposed between the weft storage device and the picking nozzle to pull back a leading end part of the weft extending between the weft storage device and the picking nozzle after the completion of a picking operation includes making the weft pullback device pull back the weft by a length greater than that by which the weft is pulled back while the fluid-jet loom is in operation, at least in a particular period in a period between the stoppage of the fluid-jet loom and the start of the first picking operation after the restart of the fluid-jet loom.

[0006] The "particular period" is (1) the entire period between the stoppage of the fluid-jet loom and the start of the first picking operation after the restart of the fluid-jet loom, (2) the entire period of stoppage of the fluid-jet loom, (3) at least a period of a shedding motion during the inching operation of the fluid-jet loom, (4) a period immediately before the start of the picking operation, (5) a desired period or (6) a period including some of the periods (1) to (5).

[0007] The fluid-jet loom may include a weft storage device, a picking nozzle, and a plurality of weft pullback devices disposed between the weft storage device and the picking nozzle. At least one of the plurality of weft pullback devices is operated both while the fluid-jet loom is in operation and while the fluid-jet loom is stopped, and at least one of the plurality of weft pullback devices is operated only while the fluid-jet loom is stopped.

[0008] Thus, the length of the weft pulled back at least in the particular period in the period between the stoppage of the fluid-jet loom and the start of the first picking operation after the restart of the fluid-jet loom is greater than the length by which the weft is pulled back after the picking operation while the fluid-jet loom is in operation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and other objects, features and advantages of the present invention will become more apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is a schematic view of a fluid-jet loom that practices a weft pullback control method in a preferred embodiment according to the present invention, in which a balloon of a weft survives immediately before a picking operation;

Fig. 2 is a schematic view of the fluid-jet loom shown in Fig. 1 in a stopped state, in which a balloon of a weft has disappeared;

Fig. 3 is a diagram of assistance in explaining a particular period in a period between the stoppage of the fluid-jet loom and the start of the first picking operation after the restart of the fluid-jet loom;

Fig. 5 is a block diagram of a pullback operation controller; and

Fig. 6 is a schematic view of a fluid-jet loom provided with two weft pullback devices, that practices a weft pullback control method in a preferred embodiment according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Figs. 1 and 2 show a principal part of a picking system included in a fluid-jet loom 1. The picking system includes a weft storage device 2 including a rotary yarn guide 7, a holding pin 8 and a storage drum 9, a picking nozzle 3 and a weft pullback device 4. A weft 5 pulled out from a yarn package 6 is passed through the rotary yarn guide 7. A part of the weft 5 is held on the storage drum 9 by the holding pin 8, and the rotary yarn guide 7 rotates to wind the weft 5 around the storage drum 9. The weft 5 thus stored on the storage drum 9 is picked by a picking operation of the picking nozzle 3. The holding pin 8 is advanced toward and retracted away from the storage drum 9 by an actuator 10.

[0011] The weft 5 is extended via the weft pullback device 4 into the picking nozzle 3. The weft pullback device 4 is disposed between the weft storage device 2 and the picking nozzle 3 to pull back the weft 5 extending through the picking nozzle 3. The weft pullback device 4 includes two fixed yarn guides 11 and 12, a movable yarn guide 13 supported on an arm so as to be movable in a space between the fixed yarn guides 11 and 12, a rotary actuator 14 for turning the arm supporting the movable yarn guide 13 to move the movable yarn guide 13, and a pullback controller 15. The fixed yarn guides 11 and 12 are fixedly supported on a frame, not shown. The arm has one end supporting the movable yarn guide 13 and the other end connected to the shaft of the rotary actuator 14. The actuator 14 turns the arm supporting the movable yarn guide 13 counterclockwise, as viewed in Figs. 1 and 2, to increase the length of a part, extending between the fixed yarn guides 11 and 12, of the weft 5 so that a part, extending through the picking nozzle 3, of the weft 5 is pulled back.

[0012] The pullback controller 15 controls the actuator 14. The pullback controller 15 receives an operation signal S1 and a timing signal S3 from a loom controller 16. While the fluid-jet loom 1 is in operation, the actuator 14 turns the arm counterclockwise, as viewed in Fig. 1, in a period between the cutting of the picked weft 5 by a yarn cutter 22 after a picking operation and time immediately before the next picking operation to move the movable yarn guide 13 away from the two fixed yarn guides 11 and 12, so that a predetermined length of a leading end part of the weft 5 extending through the picking nozzle 3 is pulled back. While the fluid-jet loom 1 is stopped the loom controller 16 gives a stop signal S2 and the timing signal S3 to the pullback controller 15 to operate the actuator 14 for a pullback operation to pull back the leading end part of the weft 5 by a predetermined length to prevent the leading end part of the weft 5 from being woven into a fabric 24 on the fluid-jet loom 1.

[0013] The loom controller 16 measures the angular position of a main shaft 18 included in the fluid-jet loom 1, gives the timing signal S3 to the pullback controller 16, and executes control operations necessary for the operation of the fluid-jet loom 1. Configuration of the pullback controller 15 is shown in Fig. 4.

[0014] While the fluid-jet loom 1 is in operation, a balloon of the weft is formed between the weft storage device 2 and the fixed yarn guide 11 and continues to exist. Consequently, the leading end part of the weft 5 extends scarcely toward the fabric 24. However, since the ballooning of the weft 5 stops and the centrifugal force acting on the weft 5 disappears when the fluid-jet loom 1 is stopped, the leading end part of the weft 5 extending between the weft storage device 2 and the picking nozzle 3 slackens and hence the weft 5 is pulled by a length corresponding to a slack in the leading end part of the weft 5 in a picking direction by a slight force exerted thereon by a fluid being jetted through the picking nozzle 3, and a length of the weft yarn 5 extends from the tip of the picking nozzle 3. Consequently, the leading end part, extending from the tip of the picking nozzle 3, of the weft 5 is liable to be accidentally woven into the fabric 24 during a repairing operation while the fluid-jet loom 1 is stopped or to be entwined with the yarn cutter 22 or warps 23 to form defects in the fabric 24.

[0015] The pullback controller 15 carries out a weft pullback control method in a preferred embodiment according to the present invention. The weft pullback control method operates the weft pullback device 4 at least in a particular period in a period between the stoppage of the fluid-jet loom 1 and the start of the first picking operation after the restart of the fluid-jet loom 1 to pull back the weft 5 by a length greater than that by which the weft 5 is pulled back while the fluid-jet loom 1 is in operation. Thus, the leading end part of the weft 5 extending between the weft storage device 2 and the picking nozzle 3 is prevented from being drawn out of the picking nozzle 3 by a length corresponding to a slack in the leading end part of the weft 5 produced when the balloon disappears toward the fabric 24 by a slight force exerted thereon by the fluid being continuously jetted through the picking nozzle 3. Therefore, the leading end part of the weft 5 does not project excessively from the tip of the picking nozzle 3 in the particular period in the period between the stoppage of the fluid-jet loom 1 and the start of the first picking operation after the restart of the fluid-jet loom 1, and hence the leading end part of the weft 5 is not woven accidentally into the fabric 24 and is not entwined with the yarn cutter 22 and the warps 23.

[0016] As shown in Fig. 3, the particular period is (1) the entire period between the stoppage of the fluid-jet loom 1 and the start of the first picking operation after the restart of the fluid-jet loom 1, (2) the entire period of stoppage of the fluid-jet loom 1, (3) at least a period of a shedding motion during the inching operation of the fluid-jet loom 1, (4) a period immediately before the start of the picking operation, (5) a desired period or (6) a period including some of the periods (1) to (5).

[0017] Referring to Fig. 4, the weft pullback controller 15 includes a control condition setting unit 19, a pullback control unit 20 and a drive unit 21. The control condition setting unit 19 is operated to specify pullback control conditions including a length of the weft to be pulled back while the fluid-jet loom 1 is in operation for the type of the weft, a length of the weft to be pulled back while the fluid-jet loom 1 is stopped for the type of the weft, angular positions of the main shaft 18 respectively for the start and end of pullback, and angular positions of the main shaft 18 respectively for start and end of the particular period in a state where the fluid-jet loom 1 is stopped. The specified pullback control conditions are stored in a storage device included in the pullback control unit 20.

[0018] While the fluid-jet loom 1 is in operation, the pullback control unit 20 detects the angular position of the main shaft 18 from the timing signal S3, controls the driving unit 21 for a specified pullback period so that the arm supporting the movable yarn guide 13 is turned counterclockwise, as viewed in Fig. 4, to pull back the leading end part of the weft 5 from the picking nozzle 3. When the operation signal S1 is stopped and the stop signal S2 is given to the pullback control unit 20, the pullback control unit 20 controls the driving unit 21 to make the weft pullback device 4 pull back the leading end part of the weft by a length greater than that by which the weft is pulled back while the fluid-jet loom is in operation, in the predetermined particular period. Thus, when the fluid-jet loom 1 is stopped and the balloon formed by a part of the weft 5 extending between the weft storage device 2 and the fixed yarn guide 11 disappears, the weft pullback device 4 pulls back a length of the leading end part of the weft 5 greater by a length corresponding to a slack in the leading end part of the weft 5 resulting from the disappearance of the balloon than that of the weft to be pulled back while the fluid-jet loom is in operation. Consequently, the leading end part of the weft 5 extending between the weft storage device 2 and the picking nozzle 3 is prevented from being drawn out of the picking nozzle 3 by a slight force exerted thereon by the fluid being continuously jetted through the picking nozzle 3. Therefore, the leading end part of the weft 5 does not project excessively from the tip of the picking nozzle 3 and hence the leading end part of the weft 5 is not woven accidentally into the fabric 24 and is not entwined with the yarn cutter 22 and the warps 23.

[0019] Fig. 5 shows a fluid-jet loom 1 similar to that shown in Fig. 1, except that the fluid-jet loom shown in Fig. 5 is provided with two weft pullback devices 4a and 4b interposed between a weft storage device 2 and a picking nozzle 3. At least one of the weft pullback devices 4a and 4b, for example, the weft pullback device 4a disposed near the picking nozzle 3, operates to pull back a fixed length of a weft 5 both while the fluid-jet loom 1 is in operation and while the fluid-jet loom 1 is stopped, and at least the other weft pullback device, for example, the weft pullback device 4b disposed near the weft storage device 2, operates to pull back a fixed length of the weft 5 only while the fluid-jet loom 1 is stopped. The positions of the weft pullback devices 4a and 4b may be interchanged.

[0020] Although the fluid-jet loom 1 described above by way of example is provided with a rotary actuator 14, the fluid-jet loom 1 may be provided with a linear actuator instead of the rotary actuator 14. The fluid-jet loom does not need to be provided with one or two weft pullback devices, but may be provided with three or more weft pullback devices. The number of the weft pullback devices is determined taking into consideration the length of the weft to be pulled back. When the fluid-jet loom is a multiple-color loom provided with a plurality of picking nozzles and a plurality of weft storage devices respectively for storing and picking different wefts, a plurality of weft pullback devices are used in combination with the picking nozzles respectively for picking the different wefts, respectively.

[0021] As apparent from the foregoing description, according to the present invention, the weft pullback control method of controlling the weft pullback device included in the fluid-jet loom makes the weft pullback device pull back the weft by a length greater than that by which the weft is pulled back while the fluid-jet loom is in operation, at least in a particular period in a period between the stoppage of the fluid-jet loom and the start of the first picking operation after the restart of the fluid-jet loom. Therefore, when the fluid-jet loom is stopped and the balloon formed by a part of the weft extending between the weft storage device and the fixed yarn guide disappears, the weft pullback device pulls back a length of the leading end part of the weft greater by a length corresponding to a slack in the leading end part of the weft resulting from the disappearance of the balloon than that of the weft to be pulled back while the fluid-jet loom is in operation. Consequently, the leading end part of the weft extending between the weft storage device and the picking nozzle is prevented from being drawn out of the picking nozzle. Therefore, the leading end part of the weft does not project excessively from the tip of the picking nozzle and hence the leading end part of the weft is not woven accidentally into the fabric and is not entwined with matters around the weft during a setting operation before restarting the fluid-jet loom, so that formation of defects in the fabric can be avoided.

[0022] When the fluid-jet loom is provided with a plurality of weft pullback devices, at least one of the weft pullback devices operates to pull back a fixed length of a weft both while the fluid-jet loom is in operation and while the fluid-jet loom 1 is stopped, and at least the other weft pullback device operates to pull back a fixed length of the weft only while the fluid-jet loom is stopped. Thus, the leading end part of the weft can be pulled back properly both while the fluid-jet loom is in operation and while the same is stopped.

[0023] Although the invention has been described in its preferred embodiments with a certain degree of particularity, obviously many changes and variations are possible therein. It is therefore to be understood that the present invention may be practiced otherwise than as specifically described herein without departing from the scope and spirit thereof. The features disclosed in the foregoing description, in the claims and/or the accompanying drawings may, both separately and in any combination thereof, be material for realising the invention in diverse forms thereof.

Claims

1. A weft pullback control method of controlling a weft pullback device (4) included in a fluid-jet loom (1) having a weft storage device (2) for storing a length of a weft (5) unwound from a yarn package (6), and a picking nozzle (3), disposed between the weft storage device(2) and the picking nozzle (3) to pull back a leading end part of the weft (5) extending between the weft storage device (2) and the picking nozzle (3) after the completion of a picking operation, said weft pullback control method comprising making the weft pullback device (4) pull back the weft (5) by a length greater than that by which the weft (5) is pulled back while the fluid-jet loom (1) is in operation, at least in a particular period in a period between the stoppage of the fluid-jet loom (1) and the start of the first picking operation after the restart of the fluid-jet loom (1).

2. The weft pullback control method according to claim 1, wherein the fluid-jet loom (1) includes a plurality of weft pullback devices (4a, 4b) disposed between the weft storage device (2) and the picking nozzle (3), at least one of the plurality of weft pullback devices (4a, 4b) operated both while the fluid-jet loom (1) is in operation and while the fluid-jet loom (1) is stopped, and at least one of the plurality of weft pullback devices (4a, 4b) is operated only while the fluid-jet loom is stopped.

Drawing