METHOD FOR REMOVING AN INCORRECT PIECE OF WEFT THREAD FROM THE SHED ON WEAVING MACHINES

Abstract: Method for removing from the shed an incorrect piece of weft thread in weaving machines, in particular an incorrect piece of weft thread (63) which extends to one end (38) of the shed (1), characterized in that the method consists of the insertion in the shed (1) from aforementioned end (38) in the form of a loop (65) of a quantity of thread which is connected to the piece of weft thread (63), where this thread is guided round a thread guide element (55,55A,69) installed at the other end of the shed; followed by the drawing from the shed (1) from the end (38) of the shed (1) from which the thread was inserted aforementioned thread in such a way that the incorrect piece of weft thread (63) is removed with it, with this being guided along the thread guide element (55,55A, 69).

Description: This invention concerns a method for removing an incorrect piece of weft thread which is not bound in by the warp threads from the shed, which may or may not have been beaten up against the fell line. A weaving machine is known from British patent no. 1.430.520 which is equipped with means for removing from the shed pieces of weft thread, in particular pieces of weft thread which have arisen as a result of weft break in the shed. In said patent in the event of a thread break both pieces of weft thread are simply pulled out of the shed by their ends which lie outside the shed. Such a method has the disadvantage that the pieces of weft thread, particularly when they have already been beaten up, are difficult to remove as they come only with difficulty free from the fell line. A solution for the faultless release of an incorrect piece of weft thread has been described in Dutch patent application no. 8602191 of applicant whereby the piece of weft thread which has already been beaten up is first released from the fell line and then removed from the shed. This method consists of the incorrect piece of weft thread closest to the weft insertion side of the shed remaining connected to, or fastened to, the weft thread supply, that if the piece of weft thread has already been bound in by the warp threads the binding is undone and that subsequently a new weft thread is inserted in the shed. The newly inserted weft thread carries, during its transport through the shed, the incorrect piece of weft thread with it, so that the latter is released in the form of a loop and subsequently removed from the opposite side of the shed. The fact that the incorrect piece of weft thread is released in the form of a loop means that only a limited force need be exercised for this purpose. In the case of a gripper weaving machine aforementioned method has the disadvantage that because of the limited motion of the grippers, the incorrect piece of weft thread cannot be pulled entirely free. Because of the fact that in the method according to NL 8602191 the newly inserted weft thread and the incorrect piece of weft thread connected to it is removed via the opposite side of the shed, this method is not easily adaptable to removing loose incorrect pieces of weft thread from the shed in combination with same. Another method has been described in EP-A-0.207.407. Hereby the newly inserted weft thread is inserted at one side of the shed and, is removed together with the incorrect piece of weft thread at the opposite side. Consequently said method shows the same disadvantages as the method described in NL-A-8602191. The object of the present invention is thus a method in which aforementioned disadvantages are systematically eliminated. To this end the invention concerns a method for removing from the shed an incorrect piece of weft thread which is not bound in by the warp threads and which extends to one end of the shed, whereby this method comprises primarily the insertion in the shed from aforementioned end in the form of a loop of a quantity of thread which is connected to aforementioned incorrect piece of weft thread, such that a pulling thread is formed, this method being characterised in that it further comprises the steps of providing a thread guide element at the end of the shed situated opposite the end from which aforementioned quantity of thread was inserted, where this thread is guided round this thread guide element; and drawing from the shed from the end of the shed from which the thread was inserted the aforementioned pulling thread in such a way that the incorrect piece of weft thread is released from the fell line in the form of a loop, is guided behind the aforementioned thread guide element, is transported back through the shed and is finally removed from the shed at the end of the shed from which aforementioned quantity of thread was inserted. In the event that one end of aforementioned incorrect piece of weft thread extends to the weft insertion side of the shed, this piece of weft thread is left by preference connected to its thread supply, after which the aforementioned quantity of thread for insertion needed for the pulling thread is then created by weft thread from the same thread supply. In a special embodiment of the invention in the event of a thread break resulting in the creation of two pieces of weft thread in the shed, both pieces of weft thread are removed in the form of a loop from the shed. With a view to illustrating the characteristic according to the invention more clearly, a number of preferred embodiments are described below but without being in any way exhaustive and with reference to the attached drawings where: figure 1 shows part of a gripper weaving machine, in particular the equipment situated next to the shed, in which a break in the weft bread has occurred in the shed; figures 2 and 3 show the clips of the feeder gripper and the carrier gripper of a gripper weaving machine; figure 4 shows a schematic view along arrow F4 in figure 1; figures 5 to 11 inclusive show step by step the method according to the invention, where figure 8 shows an enlarged view of the section indicated in figure 7 by F8; figures 12 to 16 inclusive show a special embodiment of the invention; figure 17 shows a particular special possibility for fastening aforementioned pulling thread to the loose piece of weft thread to be removed; figure 18 shows a view along arrow F18 in figure 17 during the fastening to one another of two threads; figure 19 to 25 inclusive refer to an embodiment of the invention, where use is made of a special thread carrying device. In figure 1 the shed 1 of a gripper weaving machine and the apparatus situated around it is shown. Here are shown in the known way the feeder gripper 2, the carrier gripper 3, their respective lances 4 and 5, the lance drives 6 and 7, a number of thread supplies 8 to 11 inclusive, the thread presentation mechanism 12 with the respective thread guiding elements 13 to 16 inclusive, the batten 17 with the reed 18, and the heald frames 19. Also in figure 1 the respective weft threads 20 to 23 inclusive, the most recently inserted weft thread 24, the upper warp 25, the lower warp 26, the fabric 27, the fell line 28, a first weft detector 29 for the detection of the arrival of a weft thread 24 at the end 30 of shed 1, a second weft detector or thread detector 31 for the detection of broken weft threads or excesssively long weft threads and possibly a suction nozzle or some other means 32 for keeping the end 33 of a weft thread 24 stretched are indicated. The first weft detector consists of detectors 34 to 37 inclusive which supply signals in relation to the movement of the weft threads 20 to 23 inclusive. When a weft thread breaks during insertion into the shed, the relevant weft detector detects that there is no more motion. At the end 38 of the shed next to the feeder gripper 2 a cutter 39 is located in the known way, with preferably an electrical drive 40. In a gripper weaving machine on which the weft threads 20 to 23 inclusive are left hanging in the rest state at the fabric edge 41, the weft cutter 39 is mounted in such a way that a weft thread presented to the feeder gripper is pulled into the open cutter and cut free at the beginning of the weft insertion. As further indicated in figure 1 a number of accessories are provided which can be operated in a suitable way by means of a control unit 42, such as the fastening apparatus 43 for fastening threads, and means 44 for drawing the weft threads from the shed. The fastening apparatus 43 consists for example of a conventional knotting apparatus and is consequently only schematically illustrated in the figure. Of course it contains the necessary driving means for the operation of the apparatus, as well as for presenting it to the threads to be fastened. Here the motion can for example occur by means of a pneumatic cylinder 45. The illustrated means 44 consist primarily of a combination of a mechanical thread removal apparatus 46 and a suction nozzle 47. The apparatus 46 consists primarily of two rollers 48 provided with at least one driving motor 49, which in the rest condition are located apart from one another next to the front end 38 of the shed and which can be placed against one another by a driving means 50 such as a pneumatic cylinder, this being arranged such that by their rotation a thread held between them can be removed from the shed 1. It is obvious that other thread removal devices can be used as well. Aforementioned suction nozzle 47 can be moved together with the movable roller and is situated with its front end next to the relevant roller. In a particular application a movable thread guiding element 51 is mounted at end 30 of shed 1 consisting of a hook which can by means of drive means 52 and 53 execute a translational and a rotational movement respectively. It will be obvious that the feeder gripper 2 and the carrier gripper 3 are provided at their ends with thread clips 54 and 55 known independently, which for example as illustrated in figures 2 and 3, consist primarily of lever sections 56 and 57, which at one end work in conjunction with fixed clamping surfaces 58 and 59, with the assistance of elastic means 60 and 61. Such mechanisms are for example known from Belgian patent no. 904.862 of applicant, and Belgian patent application no. 8700341 of applicant. In figures 1 and 4 a thread break 62 has occurred as a result of which on the one hand an incorrect piece of weft thread 63 has been created which is via the end 38 of the shed 1 connected to the weft thread supply 8 from which the broken weft thread 24 is delivered, and on the other hand, a loose, incorrect, broken-off piece of weft thread 64 which because of the thread break 62 is by means of the suction nozzle 32 carried further than normal and consequently extends to the second thread detector 31. The purpose of the invention consists in the first place of ensuring that the piece of weft thread 63 is fully and easily removed in the form of a loop from the shed regardless of its length. As a result of the signal from the second thread detector 31 the thread presentation mechanism 12 is controlled in such a way by means of the control unit 42 that in the first place non whatsoever of the weft threads 20 to 23 inclusive are brought in the course of the feeder gripper 2. The normal weaving process is interrupted by this and the beaten-up incorrect weft thread 24 is released by undoing the binding of the warp threads, at least if this binding already exists, by means of the known method of pick finding. Subsequently a quantity of the relevant weft thread 20 is inserted in the form of a loop 65 in the shed 1 by, as illustrated in figure 5, causing the feeder and carrier grippers 2 and 3 to execute one cycle of motion, such that one thread, hereinafter referred to as pulling thread 66, is formed. Upon the insertion of the new quantity of weft thread 20 the piece of weft thread 63 is left connected to the thread supply 8. This is achieved by not operating the weft cutter 39 and ensuring that the weft thread 63 passes freely over the cutter. During this cycle the piece of weft thread 63 is pulled free in the form of a loop 67. Figure 6 again shows a situation where the pulling thread 66 is gripped by the carrier gripper 3. Here the relevant weft thread 20 is gripped as shown in figure 3. As shown in figure 7 in its most extreme position the carrier gripper 3 comes into contact with a striker 68 which presses the clip 55 open, so that the relevant weft thread 20 is caused to be located freely behind a thread guide element, which in this case is formed by the hook-shaped part 69 of the carrier gripper. The pressing open of the clip 55 is illustrated in figure 8. It is clear that the lever part 57 exerts no pressure on the thread, so that the piece of weft thread 63 can be pulled freely along the hook-shaped part 69. Subsequently, as shown in figure 9, the rollers 48 of the thread removal apparatus 46 next to the foremost end 38 of shed 1 are presented to the pulling thread 66. By causing these rollers 48 to rotate the pulling thread 66 is pulled from the shed 1 and the piece of weft thread 63 is further released and removed from the shed 1, with it being forced to move along the hook-shaped part 69, in such a way that the piece of thread 70 which is still beaten up, if any, is further released in the form of a loop 67. As shown in figure 10 the pulling thread 66 and the piece of weft thread 63 connected to it is sucked up entirely in the suction nozzle 47. Afterwards the aforementioned means 44 are returned to the rest condition as shown in figure 11. Here the weft thread 20 is held stretched by means of the suction nozzle 47. The thread waste 71 is only cut off by means of the cutter 39 when the following length of weft thread 20 is inserted. According to a special variant of of the invention both incorrect pieces of weft thread 63 and 64 are pulled simultaneously out of the shed 1, details of this being shown in figures 12 to 16 inclusive. First of all a pulling thread 66 is inserted in the shed 1 in a similar way as shown in figures 5 and 6. What nevertheless is important is that as shown in figure 12 the grippers 2 and 3 are in the first instance not fully returned to their extreme positions, so that as shown in figure 3 the weft thread 20 remains clamped in the carrier gripper 3. As further shown in figure 12 that part of the incorrect piece of weft thread 63 which has already been pulled free by means of the separate thread guide element 51 can be taken and pulled to one side, so that the fastening apparatus 43 can be presented to the pulling thread 66 and the end 72 of the piece of weft thread 64 lying beyond the shed 1. Aforementioned thread guide element 51 may consist of any randomly chosen hook-shaped element which is capable of taking exactly one thread, namely the piece of weft thread 63 close to the carrier gripper 3. A similar hook-shaped element and its drive is for example described in Dutch patent application no 8602826 of applicant. Subsequently a fastening 73 is made as shown diagrammatically in figure 13. Afterwards the grippers 2 and 3 are removed further from one another, whereby as schematically indicated in figure 14 the clip 55 of the carrier gripper 3 comes into contact with aforementioned striker 68, so that the thread is positioned free to move behind the hook-shaped part 69. In a similar way to the previous embodiments the means 44 next to the end 38 of the shed 1 are presented to the weft thread 20, so that by actuating these the pulling thread 66 is pulled from the shed 1. What is important is that as shown in figure 15 the piece of weft thread 64 is also pulled free from the fell line 28 in the form of a loop 74 and in this way can be easily removed from the shed. It will be clear that the pulling thread 66 in the meantime may or may not be released from the thread guide element 51. From figure 16 it will be clear that both the pulling thread 66 and both pieces of the weft thread 63 and 64 connected to them are sucked into the suction nozzle 47, after which a rest condition similar to that shown in figure 11 will be reached. The thread guide elements 13 to 16 inclusive consist in the embodiment shown of eyes. As known and as can be seen in figure 1 the weft threads 20 to 23 inclusive remain connected to the edge 41 of the fabric when they are not being inserted in the shed. They are cut free only at the beginning of their insertion by means of a cutter 39. Nevertheless thread presentation systems are known such as for example described in Dutch patent application no 8600857 of applicant, where the weft threads are cut from the inserted weft thread after every insertion and where the free ends created in consequence are held in movable thread clips and are in this way presented to the feeder gripper 2 in relation to the insertion pattern. It will be obvious that the thread waste 71 is in this case cut off by a cutter specially provided to this end. The thread end created in this way is restored to the relevant thread clip. The fastening 73 may be realized in any suitable way whatsoever. The fastening may for example by made by means of knotting, by a splice, by using a special fastening agent, etc. The aforementioned special fastening agent may for example consist of a staple, a thread wound round the piece of weft thread 64 and the pulling thread 66, or a drop of wax or fast-setting adhesive applied to the threads being fastened to one another. By way of clarification figures 17 and 18 show how the pulling thread 66 and the piece of weft thread 64 can be fastened to one another by means of a fast-setting adhesive or similar. To this end use is made of an fastening apparatus 43 consisting of two elements 75 and 76 which are installed on both sides next to the end 30 of the shed 1 and which have V-shaped profiles 77 and 78 which face one another. The driving means can consist for example of the aforementioned pneumatic cylinder 45 permitting the first element 75 to be brought next to the second element 76. The second element 76, is like all the parts already mentioned, mounted in a suitable way on the frame 79 of the weaving machine and contains a channel 80 which comes out exactly in the deepest edges 81 of the V shaped profile 78 and through which, as shown in figure 18, fast-setting adhesive 82 can be supplied. According to figure 18 the fastening 73 is achieved by first applying a small quantity 83 via channel 80 of the aforementioned adhesive 82 in the edge 81 and subsequently moving the pneumatic cylinder 45 so that the first element 75 is moved next to the second element 76. By its movement the first element 75 carries the pulling thread 66 and the piece of weft thread 64 with it and pushes these together in the V shaped profile 78 in which the quantity of adhesive 83 has been applied. After this quantity of adhesive 83 has set, elements 75 and 76 can be withdrawn from one another, so that the fastened threads remain behind. In this way the threads can be fastened to one another in a quick way without having to have a precise knowledge of their whereabouts in advance. It is obvious that instead of grippers 2 and 3 use could also be made of a separate thread carrying element, for example of the type described in Belgian patent application 8700223 of applicant. The invention is consequently not just limited to gripper weaving machines but can be adopted for any type of weaving machine whatsoever. In the following the use of a thread carrying device in an airjet weaving machine is described with reference to figures 19 to 25 inclusive. In figure 19 the parts which have already been shown in figure 1 are referred to by the same reference numbers. Apart from these a number of independently known parts are shown, such as a prewinder 84 consisting of a fixed winding drum 85, a rotating winding arm 86 and thread blocking apparatus 87 which can stop or release turns respectively; a main nozzle 88, auxiliary nozzles 89; a first weft sensor 90 for the detection of the arrival a weft thread 24 at the end 30 of the shed 1; a second weft sensor or thread detector 91 located in aforementioned suction nozzle 32 for detecting broken weft threads or excessively long weft threads after these have been beaten up by the reed 18 against the fell line 28 and possibly a thread detector 92 which checks for the presence of thread in the thread canal of the main nozzle 88. The reed 18 is in this case U shaped and is provided with a thread transport channel 93. The aforementioned weft cutter 39 stands in this case directly in the extension of the fell line 28 and is by preference driven by an electrical drive 40, driven as described in Belgian patent application no. 87 00224 of applicant. Aforementioned means 44 for removing the thread from the shed consist in this case exclusively of a suction nozzle 95 connected to a suction line 94 and which moves with the batten 17. A thread detector 96 is installed between the end 38 of the shed 1 and the inlet of the suction nozzle 95. Finally in figure 19 a counter nozzle 97 and the thread carrying device 98 are shown. The thread carrying device 98 allows a motor 99 to unroll a spirally rolled thread carrying element 100, consisting for example of a relatively stiff tape of synthetic material, and pushes it from end 30 through the suction nozzle 32 into the shed 1. The thread carrying element 100 is provided on its front end with a thread clip 55A, which is illustrated only schematically in figure 19, but which is basically the same in construction as the clip which is shown in figure 3. The thread clip 55A works in the retracted state of the thread carrying element 100 in conjunction with the striker 68 mentioned above. In figure 19 a thread break 62 has occurred in the middle of the shed 1. The broken-off piece of weft thread 64 is detected by means of a second weft detector 91, which is mounted a distance D before the fell line 28 just before beating up, or at the very latest at the moment of beating up itself. As a result of the signal from the second weft detector 91 the drive 40 of the weft cutter 39 is temporarily halted in order to avoid the cutting free of the piece of weft thread 63. The drive of the weaving machine is also stopped preferably with the batten 17 in its rearmost position. When the batten 17 is moved backwards the main nozzle 88 will also move backwards, so that the distance between the latter and the start 101 of the fell line 28 is enlarged. During this action in order to prevent the piece of weft thread 102 breaking between the prewinder 84 and the shed 1 a number of turns 103 are released. The counter nozzle 97 is activated in order to prevent the released turns 103 from being prematurely inserted into the shed. The method by which only the piece of weft thread 63 is removed from the shed is illustrated step by step in figures 19 to 22 inclusive. In figure 19 the thread carrying element 100 is pushed into the shed 1 until the thread clip 55A takes the piece of weft thread 102 held taut by means of the counter nozzle 97. The weft thread 20 is pulled through the shed 1 in the form of a loop 65 by rolling up the thread carrying element 100. The piece of weft thread 63 is pulled free in the form of a loop 67. In a similar way as has already been described for the gripper weaving machine, the thread clip 55A comes into contact with the striker 68, causing it to open. In this case too the hook-shaped part 69 continues to form a thread guide element for the piece of weft thread 63. In figure 21 the suction nozzle 95 is made to operate and the carrying thread 66 and the piece of weft thread 63 attached to it are removed from the shed 1, so that the latter is pulled free over its entire length in the form of a loop 67 so that it is compelled to move behind aforementioned hook-shaped part 69. When the detector 96 no longer detects any thread the reed 18 is moved forward so that as is clearly shown in figure 22, the weft thread 20 is pushed into the weft cutter 39, so that the thread waste 71 can be cut off. Figures 23 to 25 inclusive show a variant where the piece of thread 64 is connected to the carrying thread 66 in such a way that both pieces of weft thread 63 and 64 are removed simultaneously. The action is analogous to that of a gripper weaving machine. The cutting off of the thread waste 71 takes place in the same way as in figure 22. Although the quantity of thread in the foregoing detailed description required for forming the carrying thread 66 is always inserted into the shed 1 from the weft insertion side, it will be obvious that this can also be done from the other end 30 of the shed 1, where - instead of a weft thread from one of the thread supplies 8 to 11 inclusive - use will, however, be made of a thread from a specially provided thread supply mounted next to the end 30. In this special case the invention will be intended in the first instance for releasing the piece of weft thread 64 instead of 63.

Claims: 1. Method for removing from the shed an incorrect piece of weft thread in weaving machines, in particular an incorrect piece of weft thread (63; 64) which is not bound in by the warp threads (25, 26 and which extends to one end (38; 30) of the shed (1), whereby this method comprises primarily the insertion in the shed (1) from aforementioned end (38; 30) in the form of a loop (65) of a quantity of thread which is connected to aforementioned incorrect piece of weft thread (63; 64), such that a pulling thread (66) is formed ; this method being characterized in that it further comprises the steps of providing a thread guide element (55, 55A, 69) at the end (30; 38) of the shed (1) situated opposite the end (38; 30) from which aforementioned quantity of thread was inserted, where this thread is guided round this thread guide element (55, 55A, 69); and drawing from the shed (1) from the end (38; 30) of the shed (1) form which the thread was inserted the aforementioned pulling thread (66) in such a way that the incorrect piece of weft thread (63; 64) is releases from the fell line (28) in the form of a loop (67), is guided behind the aforementioned thread guide element (55, 55A, 69), is transported back through the shed (1) and finally is removed from the shed (1) at the end (38; 30) of the shed (1) from which aforementioned quantity of thread was inserted. 2. Method according to claim 1, characterized in that in case the incorrect piece of weft thread (63) extends to the end (38) of the shed (1) located on the weft insertion side, this piece of weft thread (63) is left connected to its thread supply (8), where the aforementioned quantity of inserted thread is then formed by weft thread (20) from the same thread supply (8). 3. Metod according to claim 2, characterized in that in the case of a gripper weaving machine the weft thread (20) for forming the pulling thread (66) is carried through the shed by means of the grippers (2,3). 4. Method according to claim 3, characterized in that the thread guide element is formed by the hook-shaped part (69) of the carrier gripper (3), where for this purpose the latter is held open in its most withdrawn position by means of a striker (68). 5. Method according to claim 1 or 2, characterized in that the thread for forming aforementioned pulling thread (66) is carried through the shed (1) by means of a thread carrying device (98), where a thread carrying element (100) is pulled back and forth through the shed (1) which is provided at its free end with a thread clip (55A) which takes the relevant thread with it. 6. Method according to one of foregoing claims, characterized in that in case of a thread break (62) having occurred in the shed (1) so as to cause the formation of a piece of weft thread (63) which is connected to the quantity of thread to be inserted and a loose piece of weft thread (64) one end of which extends outside the shed (1); before the pulling thread (66) is drawn out of the shed (1), the loose incorrect piece of weft thread (64) is fastened outside the shed (1) to the pulling thread (66), so that both pieces of weft thread (63, 64) are each released in the form of a loop (67,74) from the fell line (28) and removed from the shed (1). 7. Method according tone of foregoing claims, characterized in that removal from the shed (1) of aforementioned pulling thread (66) together with one or both of the pieces of weft thread (63, 64) takes place by means of a mechanical thread removal apparatus (46) where the threads are removed between driven rollers (48). 8. Method in accordance with claim 7, characterized in that the thread waste (71) created by the removal of the pulling thread (66) and one or both of the pieces of weft thread (63, 64), are sucked into a section nozzle (47), which is mounted with its front end directly next to one of aforementioned rollers (48). 9. Method in accordance with claim 8, characterized in that in the case of a gripper weaving machine and in the case of the pulling thread (66) consisting of one of the weft threads (20,21, 22,23) the relevant weft thread (20) is held in the suction nozzle (47) until it is next inserted into the shed. 10. Method in accordance with one of claims 1 to 6 inclusive, characterized in that the withdrawal from the shed (1) of aforementioned pulling thread (66) together with one or both of the pieces of weft thread (63,64) takes place by means of a suction nozzle (95). 11. Method in accordance with claim 6, characterized in that the fastening (73) between the pulling thread (66) and the loose incorrect piece of weft thread (64) is created by knotting aforementioned threads together. 12. Method in accordance with claim 6, characterized in that the fastening (73) between the pulling thread (66) and the loose incorrect piece of weft thread (64) to be removed is created by fastening aforementioned threads together by means of a splice. 13. Method in accordance with claim 6, characterized in that the fastening (73) between the pulling thread (66) and the loose incorrect piece of weft thread (64) to be removed is created by fastening aforementioned threads by means of a fastening agent (82). 14. Method in accordance with claim 13, characterized in that the fastening agent consists of a fast-setting adhesive.

Inventors: SHAW, HENRY
Applicants: PICANOL N.V.
Application year: 1989
Main classification: D03D51
IPC codes: D03D47, D03D51