METHOD FOR CARRYING ON WEAVING FROM A SEPARATE THREAD SUPPLY AFTER A WARP BREAK, AND A WEAVING MACHINE WHICH USES THIS METHOD

Abstract: Method for carrying on weaving from a separate thread supply after a warp break, characterized in that it consists essentially of: joining the end (17) of the broken warp thread (18), which is still attached to the cloth (8), to a thread (11) from a separate thread supply (12), thus forming a new warp thread; and restarting the machine while the corresponding warp thread continues to be supplied from the separate thread supply (12), such that the new thread (11) used for this purpose remains tensioned.

Description: This invention concerns a method for carrying on weaving after a warp break, from a separate thread supply. The invention also concerns a weaving machine which uses this method. The invention has as its object a method by means of which the weaving process can be resumed in a very short space of time after it has been interrupted as a result of a break in a warp thread. In order to achieve this, the above-mentioned method consists of joining the end of the broken thread, which is still attached to the cloth, to a thread from a separate thread supply, thus forming a new warp thread; and restarting the machine, while the new warp thread continues to be supplied from the separate thread supply, such that this new warp thread remains taut. There should preferably be a supply package for the separate thread supply, while the thread should be kept taut with a tension mainly corresponding to the tension in the other warp threads. Clearly, according to the method of the invention it is possible to carry on weaving as soon as the above-mentioned thread has been joined, without waiting for the break to be fully repaired, thus saving a great amount of time. While weaving continues from the separate thread supply, the second thread end, which is still attached to the warp beam, may or may not be located and if required joined to the thread from the separate thread supply. In order to explain the characteristics of the invention, the following preferred embodiments are described, by way of example only and without being limitative in any way, with reference to the accompanying drawings, where: figs. 1 to 3 illustrate the different steps of the method according to the invention; figs. 4 to 10 show mechanisms for regulating the tension in the thread from the separate thread supply. Figs. 1 to 3 are schematic representations of a weaving machine, showing the conventional components such as the warp beam 1, the warp 2, the warp stop motion 3 with several rows of drop wires 4, the shed 5, the harnesses 6, the reed 7, the woven cloth 8, the cloth beam 9, and, also shown schematically, the main drive 10 of the weaving machine. According to the present invention, use is made of: a thread 11 taken from a separate thread supply 12, which consists of e.g. a supply package mounted on the frame of the weaving machine; a thread tensioning mechanism 13 in order to maintain a certain tension in the thread 11; a thread-joining device 14; a mechanism 15 for locating and/or gripping the first thread end 17 of the broken warp thread 18 formed as a result of a thread break 16, i.e. the end still attached to the cloth 8; one or more clips 19 which can operate on the thread 11 from the separate thread supply 12; and finally a control unit 20 to control the operation of the above-mentioned components in a suitable manner. The thread-joining device 14 can be of any type, and may for example consist of a device for forming a welded splice or an automatically-positioned tying-in device of the type described in German patent No. 599.681. The above-mentioned mechanism 15 consists for example of a series of nozzles 21 with which the first thread end 17 can be picked out of the warp 2 back from the fallen drop wire 4A, more particularly as described in Belgian patent application No. 8700254 of the present applicant. Since the device 14 and the mechanism 15 may be of any type and are already sufficiently well known they are not described in further detail. The operation of the device and of the weaving machine, and or in other words the method according to the invention, can be simply deduced from figs. 1 to 3. In fig. 1, a broken warp thread 18 is shown, as a result of which the corresponding drop wire 4A has fallen, so making an electrical contact, for example with electrode 4B, in a known way. As a result of the signal generated in this way the machine is stopped and the control unit 20 initiates the cycle described below. As also shown in fig. 1 the thread 11 can for example be kept in readiness in the thread-joining device 14, ready for the join to be made, thus saving time. As shown in fig. 2, the first thread end 17 is gripped by a mechanism 15, such that by appropriate positioning of said mechanism 15, clip 19 and thread-joining device 14, the two threads can be joined together. The first thread end 17 and the thread 11 should preferably be joined to each other while being kept taut. In the state shown in fig. 3 the join 22 has been made, while the second end 23 of the broken warp thread 18 is still caught up in the warp 2. According to the invention, the weaving machine is started up already at this moment, without waiting for the broken thread 18 to be fully repaired. As a result of the thread tensioning mechanism 13, which ensures that the tension in the thread 11 is essentially the same as the tension in the other warp threads, weaving can then be started and continued without problem. While weaving continues with the thread 11 from the separate thread supply 12, the second thread end 23 can be located, or a check can be carried out to see whether there is still a thread end 23, after which, depending on the case, the weaving machine may or may not be stopped once more and the second thread end 23 presented and joined to the thread 11, so that the separate thread supply 12 can be freed once more. However, the last-mentioned step is outwith the scope of the present invention and so is not described in further detail. Clearly, the thread tensioning mechanism 13 can be of various types. A few examples are described below with reference to figs. 4 to 10. In fig. 4, the thread tensioning mechanism 13 consists of a thread clip 24 which exerts a clamping force on the thread 11, where the amount of the force can be set on an adjustment mechanism 25 by means of an adjusting screw 26. In order to keep the thread 11 constantly under tension, use can also be made of a thread compensator 27 in which a thread guide 28 exerts a slight crossways pressure on the thread 11 by means of an elastic device 29. Fig. 5 shows another variant in which the adjustment mechanism 25 consists for example of a compression spring 30 which operates on the thread clip 24, where the spring tension can be adjusted by means of adjusting screw 26. In fig. 6, while the thread 11 is being drawn from the thread supply 12 it is guided around the circumference of a roller 31, so that said roller 31 rotates as a result of the movement of the thread 11. The rotation of the roller 31 can be braked by a brake 32, thus exerting a braking effect on the thread 11. Clearly, the brake 32 can be adjusted so that the the tension in the thread 11 is essentially equal to the tension of the other warp threads in the warp sheet 2. If the separate thread supply 12 consists of a supply package 33, then as shown in figs. 7 and 8 the above-mentioned thread tensioning mechanism 13 can work in conjunction with the package frame 34. For this purpose, use is made of a brake disk 35, which turns with the supply package 33, and a brake shoe 36 which can operate on the brake disk 35, where the braking force exerted by the brake shoe 36 can be set by means of an adjusting mechanism 37. In order to achieve uniform unspooling of the supply package 33, the thread 11 is guided through a thread eye 38 mounted on the end of an elastic arm 39, which in turn is mounted on the hinged brake shoe 36. The operation of this thread tensioning mechanism 13 can be simply deduced from figs. 7 and 8. In a variant of the invention, the tension in the thread 11 can be continuously measured and automatically regulated at a set value by means of a feedback loop. In the embodiment shown in fig. 9, in order to achieve this the thread tensioning mechanism 13 consists essentially of a thread draw-off roller 40 which co-operates with said thread 11 taken from the separate thread supply 12, an electric motor 41 to drive the draw-off roller 40, a sensor 42 to measure the tension in the thread 11 after the draw-off roller 40, and a control unit 43 which provides a feedback loop in order to regulate the tension in the thread 11 at a constant predetermined value by regulating the motor 41. This embodiment has the advantage that, if there is not enough tension in the thread 11, after the knot or join 22 has been formed and before the weaving machine is started again the draw-off roller 40 can be turned back until the correct tension is reached. In another variant, the tension in the thread 11 taken from the separate thread supply 12 is regulated so as to keep it equal or more or less equal to the tension in the other warp threads. As shown in fig. 10, for this purpose the tension in the warp threads 2 is also measured by a second sensor 44. The motor 41, the sensor 42 for measuring the tension in the thread 11 and the above-mentioned sensor 44 are coupled with each other by means of a suitable control unit 45, such that the speed of the draw-off roller 40 is regulated according to the difference in tension measured by the sensors 42 and 44. When weaving from the separate thread supply 12 the weaving machine can be started automatically, in particular by having an automatic device with two conditional functions, namely that the join 22 has been made and that the fallen drop wire 4A no longer makes contact with its electrode 4B.

Claims: Method for carrying on weaving from a separate thread supply after a warp break, characterized in that it consists of: joining the end (17) of the broken warp thread (18), which is still attached to the cloth (8), to a thread (11) from a separate thread supply (12), thus forming a new warp thread; and restarting the weaving machine, while the new warp thread continues to be supplied from the separate thread supply (12), such that the new thread (11) remains tensioned. Method as in claim 1, characterized in that the thread (11) remains tensioned such that the magnitude of the tension mainly corresponds with the magnitude of the tension in the other warp threads of the warp (2). Method as in claim 2, characterized in that the tension is regulated by exerting a constant braking force on the thread (11). Method as in claim 2, characterized in that the tension in the thread (11) from the separate thread supply (12) is measured, and that the tension in the thread (11) is regulated by means of a feedback loop. Method as in claim 4, characterized in that the tension in the other threads in the warp sheet (2) is measured, as is the tension in the thread (11) taken from the separate thread supply (12), and that the tension in said thread (11) is regulated according to the difference between the two measured values and adjusted until it is equal to the tension in the warp threads in the warp sheet (2). Method as in any of the above claims, characterized in that the weaving machine is started again automatically if two conditions are met, namely that the join (22) between the thread end (17) attached to the cloth (8) and the thread (11) from the separate thread supply (12) has been made, and that the drop wire (4A) fallen as a result of the break (16) which has been repaired no longer makes contact with the electrode (4B) with which it operates. Weaving machine which uses the method according to claim 1, characterized in that it is provided with a device consisting of: a separate thread supply (12); a thread-tensioning mechanism (13) which can operate on the thread (11) from said thread supply (12); a thread-joining device (14); a mechanism (15) for locating and/or gripping the first thread end (17) formed as a result of the warp break (16) and still attached to the cloth (8); and a control unit (20) to control the operation of the various components in a suitable manner. Weaving machine as in claim 7, characterized in that the thread-tensioning device (13) consists of an adjustable thread brake (24). Weaving machine as in claim 7, characterized in that the thread-tensioning mechanism (13) consists of a roller (31), where the thread (11) from the separate thread supply (12) is guided round the circumference of said roller (31), and an adjustable brake (32) in order to brake the rotation of the roller (31). Weaving machine as in claim 8 or 9, characterized in that the thread-tensioning device (13) also has a thread compensator (27). Weaving machine as in claim 7, characterized in that the separate thread supply (12) consists of a supply package (33), while the thread-tensioning mechanism (13) consists of a brake disk (35) which operates on said supply package (33) and which is provided with a brake shoe (36) and an adjusting mechanism (37) for regulating the braking force. Weaving machine as in claim 11, characterized in that the brake shoe (36) is swivel-mounted and bears at its end an arm (39) which can be inflected elastically and which in turn bears at its end a thread eye (38) through which the thread (11) from the separate thread supply (12) is guided. Weaving machine as in claim 7, characterized in that the thread-tensioning mechanism (13) consists essentially of: a thread draw-off roller (40) which operates on the thread (11) from the separate thread supply (12); an electric motor (41) to drive the draw-off roller (40); a sensor (42) to measure the tension in said thread (11), in particular between the draw-off roller (40) and the warp-stop motion (3); and a control unit (43) which controls the motor (41) according to the value measured at said sensor (42), such that the tension in the thread (11) supplied is regulated at a preset value. Weaving machine as in claim 7, characterized in that the tensioning device (13) consists of: a thread draw-off roller (40) which can operate on the thread (11) from the separate thread supply (12); an electric motor (41) to drive the draw-off roller (40); a sensor (42) which measures the tension in the thread (11), in particular between the draw-off roller (40) and the warp stop motion (3); a second sensor (44) which measures the tension in the other warp threads in the warp (2); and a control unit (45) which controls the motor (41) according to the values measured at the sensors (42, 44), such that the tension in the thread (11) from the separate supply is kept essentially equal to the tension in the other warp threads in the warp (2).

Inventors: SHAW, HENRY
Applicants: PICANOL N.V.
Application year: 1988
Main classification: D03J1
IPC codes: D03D49, D03J1