METHOD OF WEAVING, AND A WEAVING MACHINE WHICH USES THIS METHOD

Abstract: Method of weaving, with the characteristic that it consists essentially of drawing the weft thread (2) from at least one yarn supply (1) with non-cleaned thread, in particular yarn such as obtained directly from spinning, followed by cleaning the weft thread (2) between the yarn supply (1) and the pick insertion device (8) and then inserting the cleaned weft thread into the shed (20) by means of the pick insertion device (8).

Description: This invention concerns a method of weaving, and a weaving machine which uses this method. It is known that spinning of yarn yields yarn with irregularities such as thinnings, thickenings, knots, entanglements and wads. Such yarns are usually cleaned. This is done using a device, itself common technology, which automatically removes those sections of the spun thread which show irregularities, and which then joins the yarn together again by splicing or suchlike. The non-cleaned yarn is wound onto yarn packages, which can be used on weaving machines. Clearly, the process of cleaning the spun yarn on a separate device is a cost factor in the overall weaving process. The aim of the present invention is to provide a method of weaving whereby this factor is excluded, and which also prevents the abovementioned irregularities from being woven into the cloth. To this end, the invention concerns a method of weaving in which a textile is formed by means of warp and weft threads, and in which the weft threads are introduced into a shed formed in the warp threads by a suitable weft mechanism, with the characteristic that the method consists essentially of: drawing the weft thread directly from a supply consisting of yarn packages, known as "cops", made up of a non-cleaned yarn, in particular yarn as obtained straight after spinning; then cleaning said yarn (weft thread) between the yarn supply and the pick insertion device; and finally inserting the cleaned thread into the shed, by means of the pick insertion device, as outlined above. In a preferred embodiment of the invention, the method consists essentially of drawing the weft thread from a yarn supply made up of non-cleaned yarn, leading it through a detection device to the accumulator of a thread accumulation mechanism, and then inserting it into the shed by means of a pick insertion device; whereby, if an undesired irregularity is detected by said detection device, then successively ensuring that: the accumulator in operation at the moment the irregularity passes the detection device is stopped; the section of thread present in the accumulator is removed so that the irregularity is removed with it; and the accumulator mechanism made ready to start again. The invention also concerns a weaving machine which uses this method, with the special characteristic that the weft mechanism on the machine consists of a combination of successively: a yarn supply consisting of non-cleaned thread; a detection device to detect irregularities in the weft thread; a thread accumulation mechanism made up of at least one accumulator; a thread-removing device, which can operate in conjunction with the thread accumulation mechanism; a pick insertion device; and a control unit which controls the operation of all the abovementioned components according to a signal from the detection device. In a preferred embodiment, the invention also provides a method in which the weaving machine does not have to be stopped while the section of thread containing the irregularity is being removed. This is done using a multiple accumulation mechanism with at least two accumulators, so that while a section of thread containing an irregularity is being removed from one of the accumulators, the system switches over to the other accumulator, so enabling the weaving process to operate continuously. In order to explain the characteristics of the invention, the method of operation and a number of weft mechanisms for weaving machines according to the invention are described below, by way of example only and without being limitative in any way, with reference to the accompanying drawings, where: figs. 1 to 6 show the steps of the method, for said preferred embodiment, on a weaving machine using a weft mechanism according to the invention; figs. 7 to 10 show variants. As shown in fig. 1, in such an embodiment the weft mechanism on the weaving machine according to the invention consists essentially of a yarn supply 1 from which a weft thread 2 can be drawn, a detector device 3 in order to detect irregularities 4 in the weft thread 2, and a multiple accumulation mechanism 5 with at least two accumulators 6 and 7 which operate alternately, and a pick insertion device 8. Also shown in fig. 1 are a thread-joining device 9 and a cutting device 10. The yarn supply 1 consists essentially of an active yarn package 11 with non-cleaned thread, also known as a "cop", and a package supply mechanism 12, which usually consists of a carrousel bearing several such yarn packages 11. Presentation of the new yarn package 11 and tying its leading end to the trailing end of the active package 11 can of course also be carried out automatically. The detection device 3, which is mounted in the path of the weft thread 2, can of course consist of any type of detector capable of detecting the irregularities 4, for example an optical detector, or a detection element which makes contact with the weft thread 2, etc. In the embodiment shown, the weft accumulators 6 and 7 each consist essentially of a prewinder 13 with a winding tube 15 which rotates round the prewinder drum 14. They also incorporate a number of thread clips 16 to 19. The pick insertion device 8 will depend on the type of weaving machine, and is only shown schematically. On an airjet weaving machine, it will consist of one or more main nozzles and perhaps also an automatic threading device for the main nozzle. On a rapier machine, this pick insertion device 8 will consist of a thread presentation device and/or color selector in order to insert the required thread into the shed 20 by means of a feed gripper; and thread can then be beaten up by the reed 21. The abovementioned thread-joining device 9 is situated, or can be positioned, between the yarn supply 1 and the accumulation mechanism 5, and may consist of either a tying or a splicing device. The preferred embodiment also incorporates a number of components which for the sake of clarity are only shown in a limited number of figures and which therefore will only be mentioned later in the course of this description. The method according to the invention is explained below on the basis of the operation of the preferred embodiment, the steps of which are illustrated in figs. 1 and 6. In the state shown in fig. 1, the weft thread 2 is led to the pick insertion device 8 via the first accumulator 6. When an irregularity 4 occurs, it is detected by the detector 3. When this happens, the weft thread 2 continues to be led through the first accumulator 6 until the state shown in fig. 2 is reached, i.e. until the irregularity 4 is located in the first accumulator 6, at the same time making sure that a significant reserve R of good thread remains available between the irregularity 4 and the pick insertion device 8. At this point the first accumulator 6 is deactivated. In the meantime the weft thread in use 2 is cut after the irregularity 4 by a cutting device 10, thus producing a separated section of thread 2A, for example as shown in fig. 2. In order to ensure continuous operation of the weaving process, the second accumulator 7 is activated. Here it should be noted that in this accumulator 7 there is already a second section of thread 2B, whose leading end 22 is being held in readiness for the pick insertion device 8. As shown in fig. 2, the other end 23, together with the trailing end 24 of the original weft thread 2, is presented to the thread-joining device 9, for example by the motion of thread clip 18, and these two ends are then joined together. Thread can then be supplied via the second accumulator 7 by opening thread clip 19. The irregularity 4 can be removed in the way shown in figs. 3 and 4. The good section of thread 25 remaining in the thread reserve R is first separated, for example by using a hooking device 26 to draw it off the corresponding prewinder 13. While doing so the clip 17 is closed so that the end 27 remains in the proximity of the pick insertion device 8. The thread section 28 containing the irregularity 4 is cut away by means of the cutting device 29, and then removed completely by means of an evacuation device 30, as shown in fig. 4. The first accumulator 6 is then be made ready for operation once more by rethreading it with the good section of thread 25, as shown in figs. 5 and 6. In the variant shown, this is done by means of an automatic threading device 31, as known from Belgian patent application No. 87 00223 made by the present applicant. The thread section 25 is thus brought into the thread clip 16. The first accumulator 6 is then once ready to start operating once more when the next irregularity 4 occurs; when it does, the irregularity 4 will be removed via the second accumulator 7. Clearly, the complete weft mechanism also incorporates a control unit in order to control the cycle just described, according to a signal from the detector 3. Separating the good and bad sections of thread, 25 and 28 respectively, does not necessarily have to be done by means of a hook 26 and a evacuation device 30. In the embodiment shown in figs. 7 and 8 - which only show a part of the device - the whole length of the thread section 2A is drawn up into a tube 32 specially provided for the purpose, and the good and bad sections, 25 and 28 respectively, are separated by means of a cutting device 33. The good thread section 25 is then led through the accumulator 6 to the thread clip 16 by means of a threading device 31. Here it should be noted that drawing the thread section 2A into the tube 32 should preferably be done by sucking the thread into the tube 32. However, it could just as easily be blown in. In a variant, as shown in fig. 9, the whole length of the section 2A can be drawn out of the tube 32 and through the accumulator 6 by means of the threading device 31, so that the irregularity is drawn back to the thread-joining device 9. The bad section of thread 28 can then be cut away by means of the cutting device 34. For this purpose, the threading device 31 can be mounted before the thread-joining device 9, so that the latter is rethreaded when the thread section 2A is drawn through. The present invention of course also concerns a weft mechanism and a method which uses only one accumulator. In this case, while the irregularity is being removed the thread supply to the weft mechanism is interrupted, so that the weaving machine has to be stopped temporarily. As shown in fig. 10, it is also possible to use two separate yarn supplies 1, each with its own thread 2 running through a separate thread-joining device 9, detection device 3, cutting device 10 and accumulator, 6 or 7, and possibly also through a separate thread-removal device, for example the abovementioned hooking device 26 and an evacuation device. Both weft threads 2 are then led to the same pick insertion device 8. The method used here is essentially that when an irregularity 4 is detected, the system switches over to the second weft thread while the irregularity is removed from the first, and vice versa. Clearly, it is also possible to work with more than two weft accumulators. Fig. 11 shows yet another variant of the weft mechanism shown in fig. 10, in which a common package supply mechanism and thread-joining device 9 is used for both weft threads 2. The thread-joining device 9 can be presented alternately to each weft thread. When an irregularity 4 is removed from the weft thread 2, the thread ends 24 thus formed can be kept stretched out by means of other thread clips 35; these are necessary in particular during the absence of the thread-joining device 9. Clearly, the invention is not limited to a thread accumulation mechanism 5 of the type which uses prewinders 13; given suitable means, e.g. the tube 32, the method of the invention can also be applied to other types of thread accumulator devices. Clearly also, the yarn supply 1 consisting of non-cleaned thread can be of any type.

Claims: 1. Method of weaving in which a textile is formed by means of warp and weft threads, and in which the weft threads are introduced into a shed formed in the warp threads by a pick insertion device, with the characteristic that the method consists essentially of: drawing the weft thread (2) directly from a yarn supply (1) consisting of yarn packages (11) of non-cleaned thread, in particular yarn as obtained straight after spinning; followed by cleaning said weft thread (2) between the yarn supply (1) and the pick insertion device (8); and finally inserting the cleaned thread into the shed (20) by means of the pick insertion device (9). 2. Method of weaving as in claim 1, with the characteristic that it consists essentially of drawing the weft thread (2) from at least one yarn supply (1) consisting of non-cleaned thread, leading the weft thread (2) past a detection device (3) to the accumulator (6) of a thread accumulation mechanism (5), and then inserting the weft thread (2) into the shed (2) by means of the pick insertion device (8); such that when an undesired irregularity (4) is detected by the detection device (3), then successively: the accumulator (6) in use is stopped as soon as the irregularity (4) has passed the detection device (3); the section of thread containing the irregularity (4) is removed; and said accumulator (6) is made ready to operate once more. 3. Method of weaving as in claim 2, with the characteristic that it uses at least one multiple accumulation mechanism (5), i.e. one having at least two accumulators (6, 7), such that when the irregularity (4) has passed the detector (3), the system switches over to the other accumulator (7), and in the meantime the section of thread containing the irregularity (4) is removed from in or near the accumulator (6) previously in operation, which is then made ready to operate once more. 4. Method of weaving as in claim 3, with the characteristic that thread is supplied from just one yarn supply (1). 5. Method of weaving as in claim 4, with the characteristic that before the thread accumulation mechanism (5), the weft thread (2) is led past a detection device (3) and a cutting device (10), such that switching over to the other accumulator (7) as described above is done as soon as the irregularity (4) is detected by the detection mechanism (3), where said switching over is done by: cutting the weft thread (2) in use between the thread accumulation mechanism (5) and the point where the detection device (3) is in operation; presenting the end (23) of a section of thread (2B) present in a second accumulator (7) to a thread-joining device (9); joining this end (23) to the leading end (24) of the weft thread (2) taken from the yarn supply (1); and switching over the pick insertion device (8) to the thread (2, 2B) from the accumulator (7) which has just been activated. 6. Method as in claim 3, with the characteristic that thread is taken from more than one yarn supply (1), and that each weft thread (2) is led to the pick insertion device (8) via a separate accumulator (6, 7). 7. Method of weaving as in any of claims 2 to 6, in which use is made of a thread accumulation device (5) whose accumulator or accumulators (6, 7) consist essentially of prewinders (13), with the characteristic that the section of thread (28) containing the irregularity (4) is removed by, respectively: when the corresponding accumulator (6) ceases to operate, situating the detected irregularity (4) so as to leave a reserve length of thread (R), consisting of a good section of thread (25), on the corresponding prewinder (13), between the pick insertion device (8) and the irregularity (4); drawing the good section of thread (25) farther off the corresponding prewinder (13) concerned, and cutting the good and bad sections (25, 28) apart; and finally removing the bad section of thread (28) by drawing it off the prewinder drum (14). 8. Method of weaving as in any of claims 2 to 7, with the characteristic that resetting the accumulator (6) is done using a threading device (31) to draw the good section of thread (25) back through the corresponding accumulator (6) and bring it up to a thread clip (16). 9. Method of weaving as in any of claims 2 to 7, with the characteristic that resetting the accumulator (6) is done using a threading device (31) to draw the good section of thread (25) back through the corresponding accumulator (6) and bring it up to the thread-joining device (9). 10. Method of weaving as in any of claims 2 to 6, with the characteristic that when an irregularity (4) is detected, the section of thread (28) containing the irregularity (4) is removed by successively: stopping the accumulator (6) in use, in such a way that between the irregularity (4) and the pick insertion device (8) there remains a reserve of thread (R) consisting of a good section of thread (25); drawing the section of thread (2A), which is left on the corresponding accumulator (6), up into a tube (32) provided for the purpose; and cutting off the bad section of thread (28) containing the irregularity (4) inside the tube and evacuating it through the tube (32), and drawing the good section of thread (25) completely through the corresponding accumulator (6). 11. Method of weaving as in any of claims 2 to 6, with the characteristic that the section of thread (28) is removed by successively: stopping the accumulator (6) in use, in such a way that between the irregularity (4) and the pick insertion mechanism (8) a reserve of thread (R) consisting of a good section of thread remains accessible; drawing the section of thread (2A) up into a tube (32) provided for the purpose; drawing the section (2A) in a stretched out condition back through the corresponding accumulator (6) and also through the thread-joining device (9), and cutting off the bad section of thread (28) before the thread-joining device (9). 12. Weaving machine which uses the method according to any of the above claims 1 to 11, with the characteristic that it uses a weft mechanism that it essentially combines, successively: one yarn supply (1) with non-cleaned thread, essentially as obtained directly from a spinning process; a detection device (3) in order to detect irregularities (4) in the weft thread (2) drawn from the yarn supply (1); a thread accumulation mechanism (5) with at least one accumulator (6, 7) and incorporating a thread removal mechanism in order to remove bad sections of thread (28); a pick insertion device (8); and a control unit which operates at least the mechanism for removing the bad section of thread (28) according to a signal from the detection device (3). 13. Weaving machine which uses the method according to claim 4, with the characteristic that it uses a weft mechanism that essentially combines, successively: one yarn supply (1) with non-cleaned thread, essentially as obtained directly from a spinning process; a detection device (3) in order to detect irregularities (4) in the weft thread (2) drawn from the yarn supply (1); at least one multiple thread accumulation mechanism (5) whose accumulators (6, 7) incorporate a thread removal mechanism in order to remove bad sections of thread (28); a pick insertion device (8) which can be switched over so that it can be supplied with weft thread (2) from the appropriate accumulator (6, 7) of the thread accumulation device (5); and a control unit which switches over to the appropriate accumulator (6, 7) according to a signal from the detection device (3) and which operates the appropriate device for removing the bad section of thread (28). 14. Weaving machine as in claim 12 or 13, with the characteristic that between the yarn supply or supplies (1) and the thread accumulation mechanism (5) there is a thread-joining device (9) which can operate on the weft thread (2) taken from the yarn supply or supplies (1) and on the thread sections (2A, 2B) from the accumulators (6, 7) of the thread accumulation mechanism (5). 15. Weaving machine as in claims 12, 13 or 14, with the characteristic that between the yarn supply or supplies (1) and the thread accumulation mechanism (5) there is a cutting device (10) which can operate on the weft thread (2) being supplied at that moment.

Inventors: SHAW, HENRY
Applicants: PICANOL N.V.
Application year: 1988
Main classification: D03D47
IPC codes: D03D47