METHOD AND MECHANISM FOR REPAIRING THE WEFT SUPPLY ON WEAVING MACHINES IN CASE OF AN INTERRUPTION BETWEEN THE SUPPLY PACKAGE AND THE WEFT ACCUMULATOR

Abstract: Method for repairing the yarn supply on weaving machines in case of an interruption between the yarn package and the weft accumulator, with the characteristic that it consists essentially of: seizing the present yarn part (19) at a particular point on the yarn supply (40) in the weft accumulator (3); removing the portion of thread (20) between this point and the point of the interruption (16); taking a new yarn end (2, 12) from the same supply package (1, 10) or another and leading it to the present end (19); and joining the new end (2, 12) to the old end (19).

Description: This invention concerns a method for repairing the weft supply on weaving machines in case of an interruption of the yarn somewhere between the supply package and the weft accumulator, together with a mechanism based on this method. Such an interruption can occur as a result of a yarn break or a supply package running out when a new package has not been Connected. With systems known to date, when such an interruption occurs the weaving machine has to be stopped and the weft accumulator and main nozzle switched off, or, in the case of a rapier machine, the yarn presentation gripper has to be rethreaded and/or another weft accumulator has to be activated. The present invention then concerns a method for repairing the weft supply which makes this complicated rethreaded process unnecessary. This is achieved by repairing the weft supply before the broken yarn leaves the accumulator. In order to achieve this, the method of the invention consists essentially of: seizing the yarn at a particular point in the weft supply on the weft accumulator; removing the piece of yarn between that point and the break; taking a new yarn end from the same supply package or another and bringing it up to the end which has been seized; and joining the two ends together. This invention also concerns mechanisms for carrying out this procedure. In order to explain the characteristics of the invention, for the sake of example only and without being limitative in any way, the method and some mechanisms based on the invention are described below with reference to the accompanying drawings, where: - figs. 1 to 9 are schematic representations of the method of the invention, implemented on a weaving machine which uses a weft accumulator of the tube that consists of a prewinder drum and a winding tube; - figs. 10 and 11 show two embodiments for mounting bobbins as used in the invention; - figs. 12 and 13 show another two embodiments of the mechanism of the invention. Fig. 1 shows a mechanism based on the invention in normal operation. Here, the yarn 2 is taken from the supply package 1 and led to a weft accumulator 3 where a yarn supply 4 is formed in order to enable the weft insertion device 5 to be supplied intermittently with yarn for picking in the shed. In the embodiment shown in the diagram, the weft accumulator 3 consists essentially of a fixed prewinder drum 6 and a rotating winding tube 7. In the case of airjet weaving machines, the weft insertion device 5 consists of an injector nozzle. The mechanism also includes an auxiliary nozzle 8 which is used to thread the winding tube 7, and a yarn break detector 9. The mechanism also consists of one or more reserve packages 10, together with a mechanism 11 for presenting the reserve package to the weft accumulator 3 at the required moment. Two suction nozzles 13 and 14 and a tying-in device 15 are mounted close to the weft accumulator 3. When an interruption 16 (fig. 2) occurs, it is detected by the yarn break detector 9, resulting in eg. the yarn 12 from the reserve package 10 being presented to the winding tube 7, as shown in fig. 3. At the same time, the yarn supply 4 is cut at a particular point by means of a cutting device 17; all the coils to the left of line 18 on the underneath of the prewinding drum 6 are cut through, as shown in fig. 4. Since the yarn supply 4 is cut at a particular point on the accumulator, the remaining part 19 of the yarn supply 4 is almost certainly of good quality. Where a break occurs in the yarn 2, there is nearly always a bad length of thread; by removing the part 19 of the yarn, there is a good chance that the faulty length will be removed completely. As shown in figs. 5 and 6 the resulting yarn pieces 20 are sucked up by the suction nozzle 14. If there should happen to be a loose piece of thread on the winding tube 7, this is also sucked up by suction nozzle 14; to this end, the rotation of the winding tube 7 can be halted so that its end is positioned just before or close to suction opening 13. However, there is no reason why the winding tube 7 should not continue to rotate. As shown in fig. 7, the yarn 12 is led to suction nozzle 13, while the shortened yarn length 19 is drawn into suction nozzle 14, where it is held fast. The suction nozzles 13 and 14 can be raised over a short distance as shown in fig. 8, so that the tying-in device 15 can join the yarn 12 and the yarn end 19. Once this join has been made, winding of the yarn 12 onto the prewinder drum 6 can continue. In a variant (not shown in the figures), instead of cutting the yarn part 19 on the prewinder drum 6, the drum is turned back a few turns so that the yarn part 19 is sucked up over a short distance, thus ensuring that the yarn part 19 is joined at a point where the yarn is good. The extra length of thread formed when the join is made can be cut off automatically. If the reaction speed is fast enough, the yarn section 19 can be held fast or sucked up immediately on leaving the winding tube 7. Clearly, if the remaining yarn supply 21 is made sufficiently great, the weaving process can continue without being hindered by the repair operations. In the variant shown in fig. 9, winding of the yarn 12 on the prewinding drum 6 begins while the tying-in device 15 is still operating. In order to make it easier to change supply packages, changing can be done using systems such as shown in figs. 10 or 11. In the first system, the packages 1, 10, 22 and 23 are placed on a conveyor belt 24. In the second system, packages 1 and 10 for example can be mounted on a swivel frame so that the yarn on either package can be easily presented to the winding tube 7. Fig. 12 shows another variant of the mechanism of the invention, in which the suction nozzles 13 and 14 are replaced by one common suction nozzle 25 with two suction openings 26 and 27 connected by a slit 28. The tying-in device 15 can be mounted inside the suction nozzle 15. Fig. 13 shows yet another variant of the mechanism of the invention, in which in addition to the yarn break detector 9 there is also a yarn motion detector 29. This makes it possible to detect yarn breaks which occur after the detector 9, for instance in the winding tube 7. The winding tube 7 can also be fitted with a brake 30 in order to stop the winding tube at the correct point. Markings 32 can be placed on the brake disk 31 to enable the motion and/or position of the winding tube 7 to be monitored by means of a detector 33. Yarn detectors may also be mounted in the winding tube 7 and in the suction nozzles 13 and 14. Clearly, the coils remaining on the prewinding drum 6 can be moved along the drum so that they lie close to the new coils. Although the preceding desciption relates to a weft accumulator of the type that consists of a prewinder drum and a winding tube, the method of the invention can obviously be used for any other type of weft accumulator, eg. the free loop type. The cutting device 17 may consist of either a knife or a a pair of shears. Mechanical clamps may also be used instead of the suction nozzles 13 and 14 in order to bring the two yarn ends together in the tying-in device 15. The present invention is not limited to the embodiments described herein by way of example and shown in the accompanying figures; on the contrary, such a method and the mechanism for applying it can be implemented in many variants while still remaining within the scope of the invention.

Claims: 1. Method for repairing the yarn supply on weaving machines in case of an interruption between the yarn package and the weft accumulator, with the characteristic that it consists essentially of: seizing the present yarn part (19) at a particular point on the yarn supply (4) in the weft accumulator (3); removing the portion of thread (20) between this point and the point of the interruption (16); taking a new yarn end (2, 12) from the same supply package (1, 10) or another and leading it to the present end (19); and joining the new end (2, 12) to the old end (19). 2. Method for repairing the yarn supply on weaving machines as in claim 1, with the characteristic that joining the new yarn end (2, 12) to the present end (19) is done by sucking both ends up into a tying-in device (15). 3. Method for repairing the yarn supply on weaving machines as in claim 1 or 2, in which the weft accumulator (3) is of the type that consists of a fixed prewinder drum (6) and a winding tube, with the characteristic that the winding tube (7) continues to operate over at least a part of the repair period. 4. Mechanism for repairing the yarn supply on weaving machines according to the method in any of claims 1 to 3, with the characteristic that it consists essentially of a weft accumulator device (3) consisting of: a prewinding drum (6) with a winding tube (7); a suction device (25) with two suction openings (26, 27) joined by a slit (28), where the first opening acts on the end of the winding tube (7) and the opening acts on the surface of the prewinding drum (6); and a tying-in device (15) that operates in conjunction with the suction nozzle (25). 5. Mechanism for repairing the yarn supply on weaving machines according to the method in any of claims 1 to 3, with the characteristic that it consists essentially of: a weft accumulator device (3) with a fixed prewinding drum (6) and a rotating winding tube (7); a first suction nozzle (14) which can act on the yarn end (19) remaining in the yarn supply (4); a second suction nozzle (13) mounted next to the first, which can act on the end of the winding tube (7); and a tying-in device (15) which can operate at the openings of both suction nozzles (13, 14). 6. Mechanism for repairing the yarn supply on weaving machines according to conclusion 4 or 5, with the characteristic that a cutting device (17) is mounted on the opposite side of the prewinder drum (6) from the tying-in device (15), and that this cutting device can act on a portion of the yarn accumul­ ation (4). 7. Mechanism as in any of claims 4 to 6, with the characteristic that the rotating winding tube (7) is fitted with a brake (30). 8. Mechanism as in any of claims 4 to 7, with the characteristic that the rotating winding tube (7) is fitted with a disk (31) with markings (32) which operate in conjunction with a detector (33). 9. Mechanism as in any of claims 4 to 8, with the characteristic that a yarn motion detector (29) and a yarn break detector (3) are mounted in the path of the yarn (3), in order to detect yarn breaks.

Inventors: SHAW, HENRY
Applicants: PICANOL N.V.
Application year: 1987
Main classification: D03D47
IPC codes: D03D47