Method of discharging a weft yarn wound around a drum

Abstract: When a weft yarn (1) is broken between a fixed drum type weft yarn measuring and storing device (3) and a picking nozzle (10), the weft yarn (1) extending to the winding yarn guide (4) is delivered to a yarn sucking device (14) with certainty by generating an air current inside the winding yarn guide (4) in the picking direction and by generating an air current inside the yarn sucking device (14) in the drawing direction as the winding yarn guide (4) is confronted with the yarn sucking device (14) disposed in front of the weft yarn measuring and storing device (3) and a retaining pin (7) is kept to be advanced toward the drum (6). Thereafter the broken weft yarn (1) on the drum (6) is discharged by retracting the retaining pin (7).

Description: The present invention relates to a method of discharging a weft yarn on a drum of a drum type weft measuring and storing device. The Japanese Patent Laid-Open Publication No. 2-210043 or No. 3-180544 discloses a method of discharging a yarn. That is, if a weft yarn is broken between a picking nozzle and a drum type weft yarn measuring and storing device, an air current is generated in a yarn guide for winding a yarn guided thereby round a drum (referred to a winding yarn guide hereinafter) in the picking direction after or when a retaining pin is retracted and the sucking operation of a suction pipe confronting with the winding yarn guide is started for delivering the yarn wound around a drum to the suction pipe, which discharges the yarn out of the loom. The prior arts, however, are unreliable in delivering the weft yarn from the winding yarn guide to the yarn suction pipe, and have the following problems. That is, when the winding yarn guide jets air, the weft yarn which has been wound around a drum is unwound therefrom entailing the circular motion (revolution) of itself. As a result, the looped tip end of the unwound weft yarn not only revolves in accordance with the position of the drum from which it is unwound, but also vibrates as it is fanned by the air current, so that it is uncertain that the weft yarn reaches the suction pipe. Furthermore, when the winding yarn guide jets air, there is the possibility of unwinding of the wound yarn all at once, which prevents the weft yarn from reaching the yarn suction pipe. Accordingly, it is an object of the present invention to solve the technical problems of the prior arts set forth above and perform the delivery of the weft yarn from the winding yarn guide to the yarn suction pipe and the succeeding discharge of the weft yarn with certainty. It is performed according to the method disclosed in the unique claim. That is, when the weft yarn is broken between a fixed drum type weft yarn measuring and storing device and the picking nozzle, an air current is generated in the winding yarn guide in the picking direction while the winding yarn guide is put to be confronted with a yarn sucking device positioned in front of the weft yarn measuring and storing device and a retaining pin is kept to be advanced toward the drum, so that the weft yarn is unwound a little from the drum by the air current, but after the weft yarn is prevented by the retaining pin from being unwound therefrom, the weft yarn is drawn out only from a weft yarn package and a looped weft yarn formed between the winding yarn guide and the retaining pin is delivered to the yarn sucking device in action, thereafter the broken weft yarn on the drum is discharged by retracting the retaining pin. Thus, since the looped weft yarn extending between the winding yarn guide and the retaining pin is kept on a plane, the tip end of the loop is certainly delivered to the yarn sucking device without revolution of itself, and moreover the looped weft yarn can be delivered to the yarn sucking device with certainty since the weft yarn wound around the drum is prevented from being unwound therefrom accidentally. Fig. 1 is a view for explaining the state of the broken weft yarn between a weft yarn measuring and storing device and a picking nozzle. Fig. 2 is a view for explaining the process of delivery of the looped weft yarn from the winding weft yarn to a yarn sucking device. Fig. 3 is a view for explaining the process of discharging the weft yarn on the drum as it is unwound therefrom. Fig. 4 is view for explaining the process of the delivery of the weft yarn between the winding yarn guide and the yarn sucking device to the picking nozzle by a yarn guide. Figs. 1 to 4 show the operations of the main components of the device in performing the method of discharging a weft yarn wound around a drum according to the present invention. This embodiment assumes the employment of the device disclosed in the Japanese Patent Laid-Open Publication No. 3-104965 (U.S. Patent No. 5, 080, 144). A weft yarn 1 fed from a weft yarn package 2 is drawn into a winding yarn guide 4 in the fixed drum weft yarn measuring and storing device 3. The winding yarn guide 4 driven by a driving motor 5 measures the weft yarn 1 by winding the same round a fixed drum 6 at a given speed and stores the same thereon. A retaining pin 7 driven by an operating device 8 at the end of the picking cycle is advanced to the outer circumference of the drum 6 so as to complete the picking by retaining the weft yarn 1 unwound from the drum 6. The weft yarn 1 understream the drum 6 reaches the inside of a picking nozzle 10. When the operating device 8 retracts the retaining pin 7 in picking cycle, the retaining pin 7 comes off the weft yarn 1 so that it is ready to be picked. At that time, a compressed fluid source 11 and a control valve 12 feed a picking fluid into the picking nozzle 10, which jets the picking fluid into a shed for picking the weft yarn 1. When the weft yarn 1 is broken between the weft yarn measuring and storing device and the picking nozzle 10 during the picking operation as illustrated in Fig. 1, a yarn breakage sensor 13 detects the breakage of the weft yarn 1, for example, by detecting the absence of the weft yarn 1 on the inlet side of the picking nozzle 10. At that time, a loom control system, not shown, drives the operating device 8 upon reception of the yarn breakage signal from the yarn breakage sensor 13 to advance the retaining pin 7 to the outer circumference of the drum 6 for retaining the weft yarn 1 thereon and at the same time stops the loom instantly. Thereafter, the control system put the outlet of the winding yarn guide 4 to be confronted with the inlet side of the yarn sucking device 14 by rotating the driving motor 5. The control of rotating position of the winding yarn guide 4 can be carried out by providing a shaft encoder at a portion of the shaft of the winding yarn guide 4 or regulating the rotating amount (rotating angle) of the driving motor 5. Then, a compressed air source 15 and control valves 16a and 16b generate an air current inside the winding yarn guide 4 in the picking direction and an air current inside the yarn sucking device 14 in the drawing direction by supplying compressed air to a guide nozzle 17 fixed to the winding yarn guide 4 at the center of revolution thereof keeping the retaining pin 7 to be advanced. Whereupon, the weft yarn 1 is fed from the side of the weft yarn package 2 by the air current inside the winding yarn guide 4, is discharged from the output portion of the winding yarn guide 4 in a loop shape and enters the yarn sucking device 14 led by the looped portion thereof and further reaches the inside of the sucking inlet 19 of a yarn disposing device 18. At that time, a yarn sensor 20 confirms the arrival of the weft yarn 1 by photoelectrically detecting the presence of the weft yarn 1 adjacent to the sucking inlet 19 of the yarn disposing device 18. After confirming the arrival of the weft yarn 1, the control valve 16a stops supplying compressed air to the guide nozzle 17. As described above, since an air current is generated inside the winding yarn guide 4 in the picking direction as the retaining pin 7 is kept to be advanced to the outer circumferential surface of the drum 6 in the process of delivering the weft yarn 1 from the winding yarn guide 4 to the yarn sucking device 14, the weft yarn 1 is accurately delivered to the yarn sucking device 14. That is, since one of the end portions of the weft yarn 1 fed in a loop shape is linked with the outlet of the winding yarn guide 4 while the other is retained by the retaining pin 7, the weft yarn 1 is stably positioned at the leading tip end portion thereof, and moreover since the weft yarn 1 wound around the drum 6 is retained by the retaining pin 7, the weft yarn 1 is prevented from being fed accidentally. It is preferable to set the rotational stopping position of the winding yarn guide 4 in the delivery process to be slightly downstream the retaining pin 7 in the rotating direction of the winding yarn guide 4, because the weft yarn 1 fed in a loop shape is retained by the retaining pin 7 earlier under such situation. Thereafter, the operating device 8 retracts the retaining pin 7 and the yarn sucking device 14 sucks the weft yarn 1 which has been wound around the outer circumference of the drum 6 together with an air current and feeds the weft yarn 1 into the yarn disposing device 18 as illustrated in Fig. 3 and stops its sucking operation after a given time elapses. As a result, the weft yarn 1 on the outer circumference of the drum 6 is removed therefrom and is fed into the yarn disposing device 18 by way of the yarn sucking device 14. At this state, the weft yarn 1 extending to the winding yarn guide 4 is linearly stretched between the outlet of the winding yarn guide 4 and the inlet side of the yarn sucking device 14. Then a rotary actuator 23 turns a furcate tipped yarn guide 21 by turning the shaft 22 thereof as illustrated in Fig. 4. During the turning, the yarn guide 21 slidably clamps the weft yarn 1 in its furcate portion, thereby displacing the weft yarn 1 toward the inlet side of the picking nozzle 10, when the picking nozzle 10 jets an air current and a cutter 9 cuts the weft yarn 1 between the inlet side of the picking nozzle 10 and the yarn sucking device 14. The weft yarn 1 guided by the yarn guide 21 enters the picking nozzle 10, which is threaded with the weft yarn 1. When the yarn breakage sensor 13 confirms the threaded state of the picking nozzle 10, the yarn guide 21 returns to its standby position. Hence the picking nozzle 10 is threaded with a new weft yarn 1. Thereafter, the retaining pin 7 is advanced to the outer circumference of the drum 6 by the operating device 8 so as to be ready to retain the weft yarn on the drum. Then the driving motor 5 rotates the winding yarn guide 4 by a given amount of rotation so as to have the drum preliminarily wound with the weft yarn 1 by necessary turns for next picking. In this way, when the weft yarn 1 is broken, the broken weft yarn 1 is discharged from the outer circumference of the drum 6 and the succeeding weft yarn 1 is passed through the picking nozzle 10 and is preliminarily wound around the drum in the weft yarn measuring and storing device 3 so as to be ready for next picking. Although the yarn sucking device 14 is arranged off the axis of the drum 6 in the embodiment set forth above, it may be thereon as disclosed in the Japanese Patent Laid-Open Publication No. 3-180544, or it can be so constructed as to be displaced to a given position from a standby position. In any way, the inlet portion of the yarn sucking device 14 should be confronted with the outlet portion of the winding yarn guide 4 so as to be able to receive the weft yarn 1 by way of an air current. Moreover, although the weft yarn is fed from the weft yarn package by the air current jetted from the winding yarn guide alone according to the above embodiment, a pair of feed rollers may be provided between the weft yarn package and the weft yarn measuring and storing device for feeding the weft yarn nipped thereby as they rotate when the drawing resistance of the weft yarn is large. Furthermore, the operation of the retaining pin is not limited to the above embodiment, but for example, the retaining pin may be advanced onto the surface of the drum after the weft yarn is fed so far as not to reach the sucking device 14 at the looped tip end thereof. Since an air current is generated inside the winding yarn guide in the picking direction as the retaining pin is kept to be advanced to the outer circumference of the drum, the looped weft yarn formed between the retaining pin and the winding yarn guide is increased in its extension toward the inlet of the sucking device since it is fed only from the winding yarn guide. Accordingly, the tip end of the weft yarn in a loop shape is stably positioned, and moreover, since the weft yarn wound around the drum is prevented from being unwound accidentally, the weft yarn can be delivered to the yarn sucking device with certainty.

Claims: A method of discharging a weft yarn (1) in a jet loom when said weft yarn (1) is broken between a picking nozzle (10) and a fixed drum type weft yarn measuring and storing device (3), wherein a looped weft yarn (1) extending between a winding yarn guide (4) and a drum (6) in said weft yarn measuring and storing device (3) is delivered to a yarn sucking device (14) confronting the outlet of said winding yarn guide (4) by generating an air current in said winding yarn guide (4) of said weft yarn measuring and storing device (3) in the picking direction, thereafter the delivered weft yarn (1) is drawn so as to discharge the weft yarn (1) on the drum (6), characterized in that said looped weft yarn (1) is delivered in a loop shape from said winding yarn guide (4) to said yarn sucking device (14) while a retaining pin (7) is kept to be advanced to said drum (6) for preventing the weft yarn (1) wound around the drum (6) from being unwound, and in that said retaining pin (7) is retracted from the surface of said drum (6) to discharge the weft yarn (1) from the drum after said sucking device (14) receives said looped weft yarn (1).

Inventors: TAKEGAWA YUJIRO, TAKEGAWA, YUJIRO
Applicants: TSUDAKOMA IND CO LTD, TSUDAKOMA KOGYO KABUSHIKI KAISHA
Application year: 1993
Main classification: D03D47
IPC codes: D03D47