METHOD FOR INSERTING AND RETRIEVING A WEDGE THREAD ON A WEBING MACHINE, PRE-RINSE DEVICE FOR A WEBING MACHINE AND WEBING MACHINE

Description

[0001] The present invention relates to a method for inserting and retrieving a weft thread on a weaving machine, in particular an air-jet weaving machine, in which method a weft thread to be inserted is temporarily stored on a drum, wherein during the temporary storage the weft thread is fixed on the drum by a fixing element located in a fixing position, the weft thread is released for weft insertion, wherein the fixing element is moved from the fixing position to a release position, and the weft thread is unwound and inserted from the drum in an unwinding direction to form a thread balloon, and in which the weft thread is retracted by means of a retrieving device after the weft insertion has taken place. Furthermore, the invention relates to a pre-winding device for a weaving machine and to a weaving machine.

[0002] Methods and devices for inserting and retrieving a weft thread have become known in various designs on weaving machines. For example, weft thread retrieval devices have become known for tensioning the weft thread after weft insertion.

[0003] Furthermore, it has become known on rapier weaving machines to retract the weft thread end presented to the rapier a short distance using a retraction device before it is grasped by the rapier. To do this, a finger is pivoted into the path of the weft thread using an actuating lever, and the now shortened weft thread end is presented to the rapier. Such a thread retraction unit is shown, for example, in DE 35 24 727 A1.

[0004] With air-jet weaving machines, however, the problem often arises that the weft thread end is damaged over a greater length by the pressure pulse at the thread start in the main nozzle. This damage is then also visible in the finished fabric as fabric defects. To avoid this, the weft thread length is often increased on air-jet weaving machines until the defects caused by the compressed air exit the shed on the right side of the fabric and end up in the right-hand waste.

[0005] US Pat. No. 3,370,618 A proposes a dispensing and measuring device for precisely measuring the length of the weft thread to be inserted. Furthermore, the device is also intended to be able to retract the weft thread end into the nozzle. This is done by means of a linearly movable tube, where the thread is then clamped by a clamping element.

[0006] DE 102 10 911 A1 proposes retracting the weft thread from the blowing area of ​​the main blowing nozzle after weft insertion is complete. For this purpose, a retraction device is arranged between the prewinding device and the main blowing nozzle. The retraction device comprises a pivoting arm with a deflection element for the weft thread. After retraction, the weft thread remains taut thanks to the suction effect of the main blowing nozzle, without exposing the weft thread end to an excessively strong, damaging air stream. Fabric defects can also be reduced this way. The retraction unit can also serve as a thread brake, slowing the weft thread toward the end of weft insertion.

[0007] Similar to DE 35 24 727 A1, SE 154 756 C1 also pivots a finger with a needle into the path of the weft thread to retract it. To then release the weft thread, the needle is actively retracted. This retractor is also located between the nozzle and the prewinding device.

[0008] Similarly, WO 2005 / 064059 A1 also shows a retraction device arranged immediately after a funnel-shaped balloon limiter. This device can also serve both as a thread brake and a retraction device. However, accelerating the thread in the main nozzle can still cause damage to the weft thread, which impairs the quality of the fabric.

[0009] The object of the present invention is to propose a method for inserting and retrieving a weft thread that avoids fabric defects and enables improved weft insertion. Furthermore, a corresponding prewinding device and a weaving machine with such a prewinding device are to be proposed.

[0010] The problem is solved by a method, a prewinding device and a weaving machine having the features of the independent patent claims.

[0011] In a method for inserting and retrieving a weft thread on a weaving machine, in particular an air-jet weaving machine, a weft thread to be inserted is temporarily stored on a drum. During the temporary storage, the weft thread is fixed to the drum by a fixing element located in a fixing position. The weft thread is released for weft insertion, wherein the fixing element is moved from the fixing position to a release position, and the weft thread is unwound and inserted from the drum in an unwinding direction, forming a thread balloon. After weft insertion, the weft thread is retracted by means of a retrieval device.

[0012] It is proposed that the weft thread is grasped and retracted in a pick-up position after the fixing element and in the area of ​​the thread balloon.

[0013] Likewise, in a pre-winding device for a weaving machine, in particular an air-jet weaving machine, with a drum for temporarily storing a weft thread to be inserted, with a fixing element for the weft thread which is assigned to the drum and can be moved from a fixing position into a release position, and with a retrieval device for retracting the weft thread after the weft insertion has taken place, it is proposed that the retrieval device is arranged in the pre-winding device in the thread path after the fixing element and that the retrieval device has a driver for the weft thread which grips the weft thread in a pick-up position after the fixing element and in the region of a thread balloon which forms during the weft insertion.

[0014] By retracting the weft thread using the retractor, the weft thread can now be retracted so far that only a relatively short piece remains in the main nozzle. If this very short piece of thread is damaged by the compressed air during acceleration of the weft thread in the main nozzle, this is not a problem because this short piece ends up in the unavoidable right-hand waste.

[0015] By arranging the retraction device in the prewinding device in the thread path downstream of the fixing element, a very compact unit can be created that requires very little installation space. In addition, this arrangement allows the weft thread, which is stretched between the drum and a thread guide element next to the drum after weft insertion, such as a balloon limiter, to be securely gripped between the fixing element on the drum and the thread guide element. It is therefore not necessary to guide the weft thread permanently, even during weft insertion, in the retraction device. This prevents weft insertion disruptions. The weft thread can be retracted particularly effectively because it is gripped in the thread path directly downstream of the fixing element. For this purpose, a retraction device with a rotating driver is used.

[0016] The advantages of the invention also apply to a corresponding weaving machine, in particular an air-jet weaving machine, with a weft thread insertion system and such a prewinding device, so that protection is also claimed for this.

[0017] Furthermore, it is advantageous if the weft thread is retracted by the retraction device into a main nozzle of a pneumatic weft thread insertion system of the weaving machine. In the weaving machine, it is correspondingly advantageous if the weft thread insertion system is designed as a pneumatic weft thread insertion system with at least one main nozzle. The weft thread is retracted in such a way that, after retraction, it is still just within the blowing area of ​​the main nozzle. This not only securely holds the weft thread by the holding air of the main nozzle, but also prevents the weft thread end from being significantly damaged by the holding air before weft insertion.By pulling back only far enough that the end of the weft thread is still in the blowing area of ​​the main nozzle, damage to the weft thread due to acceleration in the main nozzle is limited to the very short section located in the thread path in front of the injector of the main nozzle. The main nozzle usually contains a mixing tube and an injector by means of which compressed air is introduced into the mixing tube, as shown, for example, in document DE 102 24 078 B3. This very short section of the weft thread is found in the right-hand waste or in the catcher bar after weft insertion and therefore does not impair the fabric quality. It is therefore no longer necessary to increase the weft thread length and thereby produce unnecessary amounts of waste.

[0018] According to the invention, the weft thread is gripped by a carrier of the retrieval device that can rotate on a circular path around the drum and is retracted by the further movement of the carrier on the circular path. In the retrieval device, the carrier can rotate on a circular path around the drum. For this purpose, the retrieval device advantageously has a drive for driving the carrier. The retrieval device can therefore be designed very simply. The yarn can always be gripped by the carrier in the same pick-up position close to the drum in a process-reliable manner, without the need for complex adjustment work. Due to its comparatively simple technical design, the retrieval device is also suitable as a retrofit solution for a wide variety of weaving machines.

[0019] According to an advantageous embodiment of the retrieval device, it is also advantageous if the driver is designed as an open hook. By means of an open hook, the weft thread stretched between the fixing element and the next thread guide element, for example, a balloon limiter, can be gripped in a particularly reliable manner.

[0020] It is also advantageous if the carrier is driven discontinuously on the circular path. The carrier is periodically moved between the pick-up position and a delivery position, where the weft thread is released again. In each weaving cycle, the carrier grasps the weft thread in the pick-up position and releases it again in the delivery position, then returns to the pick-up position to grasp and retract the weft thread of the following weaving cycle.

[0021] According to an advantageous embodiment, the driver is moved in a circular path, wherein the driver is moved from the pick-up position via a retraction area back into the pick-up position and wherein, after retracting the weft thread, the driver is moved at a reduced speed in the retraction area and / or is temporarily stopped. In the retraction device, it is correspondingly advantageous if the driver can be moved discontinuously on the circular path from the pick-up position via a retraction area back into the pick-up position. For this purpose, the retraction device advantageously has a stepper motor or a servo motor as a drive. The retraction area can serve, for example, to keep the driver outside the sphere of influence of the forming thread balloon during weft insertion, for which purpose the driver is driven at a reduced speed.The driver can also be temporarily stopped in a rest position located within the retraction range. Even temporarily stopping the driver can serve to keep the driver outside the influence of the forming thread balloon during weft insertion. According to another design, however, the rest position can also serve to securely hold the weft thread still connected to the driver and position the weft thread end in the desired position in the main blowing nozzle. It is also conceivable to provide two different rest positions for the driver.

[0022] However, according to another embodiment, a continuous drive of the driver is also possible without reducing the speed in the retraction range or without stopping in the rest position.

[0023] It is particularly advantageous if the driver grips the weft thread immediately after the fixing element in relation to the thread path. It is also advantageous for the retrieval device if the retrieval device is arranged in the prewinding device such that the pick-up position is located immediately after the fixing element in the thread path. The driver preferably grips the weft thread at a distance of between 1 mm and 50 mm from the fixing element. The weft thread can be gripped particularly well by the driver in this position. In addition, by gripping the weft thread early in the thread path close to the fixing element by means of a rotating retrieval device, it can be retracted a particularly large distance and thus particularly effectively.

[0024] Additionally or alternatively, it is advantageous if the driver grips the weft thread in front of a thread guide element closest to the drum in relation to the thread path. As already described, this allows the weft thread to be gripped particularly well. Furthermore, with this arrangement, no thread guide elements are required within the retraction device, which could disrupt weft insertion due to their frictional effect. The weft thread is adequately guided between the drum or the fixing element and the next thread guide element, for example, the main nozzle.

[0025] According to a further advantageous embodiment, the weft thread remains connected to the driver located in the retraction area until the next weft insertion. In this case, as already described above, the weft thread connected to the driver is securely held in the desired position and the weft thread end is securely positioned in the desired position in the main blow nozzle. As long as the driver is moving in the retraction area and has not been stopped, it only moves slowly in any case. In addition, during the movement on the circular path, the distance of the driver from the fixing element in the retraction area only increases very slightly, so that the weft thread hardly changes its position even with a further moving driver.

[0026] In this process, it is also extremely advantageous if the driver is driven in the unwinding direction of the weft thread. This can facilitate the release of the weft thread from the driver for the subsequent weft insertion.

[0027] It is therefore particularly advantageous if, after the weft thread has been released for weft insertion by the fixing element, the weft thread automatically detaches from the driver due to the thread tension and centrifugal force acting on it during weft insertion. The release can therefore occur solely through the balloon-like unwinding movement of the weft thread. However, the release of the weft thread from the driver can also be assisted by the driver being brought to a standstill in a rest position, as described above. However, no active elements need to be controlled for release. Because the weft thread detaches itself from the driver during weft insertion without active control, the retrieval device does not cause any delays or incorrectly timed releases during weft insertion.

[0028] It is advantageous if, after the weft thread has been released for weft insertion, the driver is accelerated and moved further into the pick-up position. The driver can then continue its circular movement during weft insertion and quickly return to the pick-up position in order to grasp and retract the next weft thread in the pick-up position. It is particularly advantageous if the driver is only accelerated after the weft thread has been released from the driver or, if it was stationary, is set in motion again and moved further into the pick-up position. This can assist in the release of the weft thread from the driver. In addition, the driver can be kept well outside the sphere of influence of the forming thread balloon and does not hinder the weft insertion.

[0029] It is advantageous if the weft thread runs unguided through the retrieval device during weft insertion. This allows the weft thread to run freely between the drum and the next thread guide element during weft insertion and is therefore not subject to any frictional influences that could impair weft insertion. This allows for safer and faster weft insertion.

[0030] According to a particularly advantageous development of the method, the weft insertion is also started before a weft thread insertion channel of the weaving machine is exposed by the opening shed. For example, the weft insertion is started at a weaving machine angle of less than 50°, preferably less than 40°, particularly preferably less than 35°. Because the weft thread is retracted very far into the main nozzle by means of the retractor, it can now be started earlier than is usual in the prior art. The weft insertion can be accelerated as a result, allowing either higher speeds or economical weft insertion with less pressure. In addition, due to the earlier thread start, the weft thread tip already has a high speed when it leaves the main nozzle, so that the thread tip flies stably and thus reliable weft insertion is possible.

[0031] In the retrieval device, it is further advantageous if the diameter of the carrier's circular path is larger than the diameter of the drum. This can assist in securely gripping the weft thread in the pick-up position. For this purpose, the carrier preferably has a somewhat longer catching contour, which is oriented from the diameter of the carrier's circular path toward the center of the carrier's circular path. This enables the retrieval device to accommodate various drum diameters.

[0032] It is also advantageous if the driver's rotational axis is offset from the drum's axis. This allows the driver to easily pick up the weft thread in the pickup position without getting in the way of the subsequent weft insertion.

[0033] The axial offset is therefore particularly advantageous in combination with the previously described larger diameter of the carrier's circular path. This allows the carrier to be brought particularly close to the circumference of the drum in the pick-up position to grasp the weft thread. However, after the weft thread is released from the carrier, the carrier moves away from the circumference of the drum and therefore does not interfere with the unwinding of the weft thread turns.

[0034] Furthermore, it is advantageous if the retraction device has an externally toothed ring on which the driver is arranged and which can be driven by the drive. This makes it possible to arrange the retraction device directly on the prewinding device, for example, directly on a balloon limiter of the prewinding device. The thread path can pass through the interior of the ring in a particularly advantageous manner. The weft thread is thus only engaged with the retraction device during retraction, but runs through the interior of the ring without engagement during weft insertion. Active release elements, which would have to be controlled by the weaving machine control, are thus unnecessary, which also helps to avoid weft insertion malfunctions.

[0035] Further advantages of the invention are described in the following exemplary embodiments. They show, schematically: Figure 1 a weaving machine with a prewinding device with a retrieval device in a first situation shortly after weft insertion, Figure 2 the weaving machine of Figure 1 in a second situation after weft insertion and after cutting the weft thread, Figure 3 the weaving machine of Figure 1 in a third situation after retracting the weft thread, Figure 4 a view of a drum of the prewinding device with the retrieval device seen from the shed in a first situation when gripping the weft thread, Figures 5 & 6 a view of the drum of the Figure 4 in a second and third situation when pulling back the weft thread, Figure 7 a view of the drum of the Figure 4 in a further situation after retracting the weft thread, Figure 8 a view of the drum of the Figure 4 in another situation when releasing the weft thread, Figure 9 a view of the drum of the Figure 4in another situation during the shot entry, Figure 10 a view of the retrieval device and a balloon limiter seen from the weft thread supply, as well as Figure 11 an alternative embodiment of a weaving machine with a prewinding device with a retrieval device during weft insertion.

[0036] In the following description of the exemplary embodiments, identical or at least comparable features in their design and / or mode of operation are provided with the same reference numerals. Furthermore, these are only explained in detail when they are first mentioned, while the following exemplary embodiments only address the differences from the previously described exemplary embodiments. Furthermore, for reasons of clarity, often only one or a few of several identical components or features are labeled.

[0037] Figure 1shows a schematic representation of a weaving machine 1 with a pre-winding device 7 with a retrieval device 9 in a first situation shortly after the weft insertion. The weaving machine 1 has, in the usual way, a weft thread supply 6 on an insertion side ES, from which a weft thread 5 is unwound and fed to the pre-winding device 7. The pre-winding device 7 has a drum 8 on which the weft thread 5 is laid down in several turns by means of a winding disk (not shown). From the drum 8, the weft thread 5 runs through a balloon limiter 12 to a weft insertion system 4 of the weaving machine 1. The weft insertion direction SR is marked with an arrow. To separate the weft thread 5 after the weft insertion has taken place, a separating device 25 is also arranged on the insertion side ES.

[0038] The windings of the weft thread 5 deposited on the drum 8 are held there by means of a fixing element 11. The fixing element 11 is located in a fixing position I for holding the weft thread 5 (see Figures 4 - 9 ) and can be moved to a release position II (see Figures 4 - 9 ). The fixing element 11 is designed, for example, as an extendable pin which can be advanced towards the drum 8. For weft insertion, the fixing element 11 is then moved into the release position II and a predetermined number of turns of the weft thread 5 is drawn off the drum 8 during the weft insertion. The number of drawn-off turns can be detected by a sensor so that the predetermined number of turns is always drawn off during a weft insertion. After the weft insertion has been completed, the fixing element 11 is then moved back into the fixing position I.

[0039] The weft thread insertion system 4 is pneumatically designed in the present case and comprises, in a conventional manner, a main nozzle 20 arranged on the insertion side ES of the weaving machine 1. In this case, only one main nozzle 20 is shown. However, it is also possible and usual for two main nozzles 20 to be arranged one behind the other on the insertion side ES. The main nozzle 20 can be pressurized with compressed air. To hold the weft thread 5 until the next weft insertion, the main nozzle 20 can be pressurized with a lower air flow, the so-called holding air. For the weft insertion, however, the main nozzle 20 can be pressurized with a stronger air flow, the so-called main air. The end of the weft thread 5 is thereby accelerated and inserted into the open shed 2. The shed 2 is formed in the usual way by alternately raising and lowering adjacent warp threads 3.After the weft insertion has been completed, the weft thread 5 is beaten up by means of a reed 10 in a likewise known manner. In the case of an air-jet loom as shown here, the reed 10 has a weft thread insertion channel 24, into which the weft thread 5 is inserted by means of the main nozzle 20 and in which the weft thread 5 is transported through the shed 2. For this purpose, the weft thread insertion system 4 comprises a plurality of relay nozzles (not shown here) distributed over the reed 10, which assist the transport of the weft thread 5 through the shed 2. On the side of the loom 1 facing away from the insertion side ES, the weft thread insertion system 4 also has a suction nozzle 22, which catches and takes up the inserted weft thread 5. In the situation shown here, the weft thread 5 has just been inserted and taken up by the suction nozzle 22.In the present weaving machine 1, a deflection nozzle 23 is also provided, which, by means of an air stream, unthreads the weft thread 5 protruding from the shed 2 from the suction nozzle 22 and moves it in the direction of the fabric take-off WR so that it does not interfere with the further weft insertions.

[0040] In such pneumatic weft insertion systems 4, the weft thread 5 is often damaged at thread start due to the acceleration in the main nozzle 20. This problem occurs particularly with untwisted filament yarns. This damage is then often visible later as defects in the finished fabric. These problems can also occur with core yarns. Therefore, in the prior art, the weft thread length was often increased so that the damage, which primarily affects the weft thread end, is transported through the shed 2 and removed as weft thread waste on the right-hand side of the weaving machine 1, opposite the insertion side ES. Retrieval devices 9 have also been used in the prior art to retract the weft thread 5 from the blowing area of ​​the main nozzle.The weft thread 5 then remains taut by the main nozzle 20, but the weft thread end is no longer damaged by a strong air stream.

[0041] Such a retrieval device 9 for retrieving the weft thread 5 after weft insertion is arranged in the present weaving machine 1 between the drum 8 and the balloon limiter 12. The retrieval device 9 has its own drive 15. Its exact function is explained in more detail below. Figures 4 - 9 described in more detail. It is understood that each color has its own prewinding device 7 with its own rewinding device 9.

[0042] However, a balloon limiter 12 is not absolutely necessary. According to an alternative design of the weaving machine, which is Figure 11As shown, only one thread guide element 28 is arranged downstream of the prewinding device 7. The thread guide element 28 could also be arranged directly on the prewinding device 7. The thread guide element 28 could, for example, be designed as a ceramic eyelet. Figure 11 shows the weaving machine 1 during weft insertion. It is also evident that the weft thread 5 is unwound from the drum 8, forming a thread balloon 21. Otherwise, the weaving machine 1 corresponds to the one shown in the Figure 1 shown.

[0043] Figure 2 now shows the weaving machine 1 of the Figure 1in a second situation after weft insertion and after cutting weft thread 5. As can be seen, in this situation weft thread 5 has already been cut on the insertion side ES. Likewise, the weft thread end on the side opposite the insertion side ES has already been deflected by the deflection nozzle 23 toward the fabric take-off. The cut weft thread end on the insertion side ES of weaving machine 1 still protrudes slightly beyond the end of the main nozzle 20.

[0044] Figure 3 still shows the weaving machine 1 of the Figure 1 in a third situation after the retraction of the weft thread 5. After the weft insertion, the fixing element 11 was moved from the release position II to the fixing position I, where it fixes the weft thread 5 wound on the drum 8. By means of the retrieval device 9, the now stationary weft thread 5 was retracted. As the Figure 3can be removed, the weft thread 5 in the main nozzle 20 has been retracted so far that only a very short piece remains. The weft thread 5 has been retracted so far that it is just in the blowing area of ​​the main nozzle 20, i.e. still in front of the mouth of the injector (not shown). As a result of this retraction of the weft thread 5, when the weft thread 5 is accelerated only a very short piece is exposed to the harmful effects of the main air. However, since an unavoidable right-hand waste is always created due to the process, even severe damage to this very short piece is not a problem. This very short piece is located in the unavoidable right-hand waste after the weft insertion and is disposed of with it.Due to the further retraction of the weft thread 5, the damaged weft thread end leaves the shed 2 on the side opposite the insertion side and therefore cannot cause any fabric defects.

[0045] However, this not only reduces the right-hand weft thread waste by about 10-14 cm, but also allows, as is particularly the case with Figure 2As can be seen from the figure, the weft thread end projecting over the shed 2 on the right is very short, numerous other advantages are achieved. For example, the shortened weft thread end makes blockages of the suction nozzle 22 and the deflection nozzle 23 much less likely to occur. Likewise, in the prior art, blockages of the spreader bar (not shown) frequently occurred due to long, laterally projecting weft thread ends. This, too, is avoided by the now much shorter weft thread ends projecting over the side of the shed 2 or the fabric. Likewise, winding-up problems of the right-hand catching strip (also not shown) can be avoided.

[0046] Another particularly advantageous feature is that, due to the retraction of the weft thread 5 almost to the mouth of the injector of the main nozzle 20, the weft thread is already accelerated in the main nozzle 20 and thus exits at an already high speed. The weft thread 5 thus leaves the main nozzle 20 in a stretched state and at a high speed, making it easier to insert into the weft insertion channel 24 of the reed 10. This leads to a more stable weft insertion. Problems such as "walking stick formation," in which the weft thread 5 located further behind overtakes the leading weft thread end, can also be avoided.

[0047] Another advantage is that the weft thread 5 can be started before the opening shed 2 has released the weft thread insertion channel 24, since it is still located within the main nozzle 20 at the thread start. By the time the weft thread end has traveled its way to the shed 2, the shed is already sufficiently open. The thread start can thus take place earlier, allowing an increase in speed and thus an increase in production of the weaving machine 1. For example, a thread start is already possible at a weaving machine angle of approximately 30°.

[0048] Since the weft thread 5 can be accelerated earlier, it has already almost reached its maximum speed by the time it reaches the shed 2. It is therefore also advantageous to perform the weft insertion with less air pressure, thereby operating the weaving machine 1 in an energy-efficient manner.

[0049] Weft insertion disturbances, which can be caused by the holding air from adjacent main nozzles 20, are also avoided by retracting the thread into the main nozzle 20. The weft thread end is still located within the main nozzle 20 during acceleration or thread start and therefore cannot be disturbed by air turbulence from adjacent main nozzles 20.

[0050] The return device 9 according to the invention and its mode of operation will now be explained with reference to the Figures 4 to 10 described. The Figures 4 - 9 show a schematic plan view of the retrieval device 9 and the drum 8 of the prewinding device 7 seen from the shed 2. The Figure 10 shows a schematic plan view of the retrieval device 9 and the balloon limiter 12 seen from the weft thread supply 6.

[0051] Again Figure 10As can be seen from the drawing, the retrieval device 9 includes a driver 13 for the weft thread, which driver is designed in a hook-like manner and rotates on a circular path 14. The driver 13 has a catching contour 27, by means of which it can grip a stretched weft thread 5, as will be described below. The driver 13 is arranged on a rotatably mounted ring 18, which is connected to a gear 26 via an external toothing 19 and is driven by the latter. The gear 26 is in turn driven by the drive 15, which is only shown in a hidden manner here. The externally toothed ring 18 and thus also the driver 13 rotate on the circular path 14 around the axis of rotation 16 of the driver 13. In order to enable a controlled and, if provided, discontinuous or even intermittent drive of the driver 13, the drive 15 is preferably designed as a stepper motor.The inner circumferential surfaces of the balloon limiter 12 are still visible inside the externally toothed ring 18. For information, the drum 8 of the prewinding device 7 with a diameter of DT is also indicated in dot-dash lines, which is not visible in this view. As the . Figure 10 can be removed, the driver 13 also rotates around the drum 8. Furthermore, DK denotes the diameter of the circular path 14 of the driver 13.

[0052] As already mentioned Figure 11As mentioned, a balloon limiter 12 does not necessarily have to be present; it could also be provided with just a thread guide element 28. The functioning of the retrieval device 9 is the same in each case. According to another embodiment of the retrieval device 9, not shown here, the retrieval device 9 does not have an externally toothed ring 18, but rather a catch hook attached to a driven shaft. This rotates 360° around its own axis. Otherwise, the functional principle of this embodiment corresponds to that of Figure 10 The following explanations of the Figures 4 - 9 therefore refer expressly to different designs of retrieval devices 9 and weaving machines 1.

[0053] The process of retracting the weft thread 5 is now described using the Figures 4 - 9 described.

[0054] Figure 4shows a view of the drum 8 with the retrieval device 9 seen from the shed in a first situation when gripping the weft thread 5. This situation corresponds to the one in the Figure 2 illustrated situation, in which the weft thread 5 was cut straight after insertion. Likewise, in this situation, the fixing element 11 was already moved from the release position II (see Fig. 8 ) into the fixing position I, in which it fixes the weft thread 5 on the drum 8. In this situation, the driver 13 rotating on the circular path 14 is just in the pick-up position AP, in which it picks up the weft thread 5, which is between the fixing element 11 and the balloon limiter 12 (see Fig. 1 ) is stretched. The balloon limiter 12 itself is here and in the Figures 5-9not visible and is located in front of the drawing plane. In the present example, the pick-up position AP is located in the weft insertion direction immediately after the fixing element 11. There, the weft thread 5 can be gripped particularly well by the driver 13.

[0055] In Figure 5a second situation is shown during the retraction of the weft thread 5. In this situation, the driver 13 has already moved a short distance from the pick-up position AP in a counterclockwise direction on the circular path 14 and has picked up the weft thread 5 with its catching contour 27. The weft thread 5 is now stretched between the fixing element 11, the driver 13 and the balloon limiter 12 (or alternatively a thread guide element 28). Since the weft thread 5 is fixed to the drum 8 by the fixing element 11, but the weft thread end is held movable in the main nozzle 20, the weft thread 5 is now retracted into the main nozzle 20 by the further movement of the driver 13.

[0056] In Figure 6A third situation is shown during the retraction of the weft thread 5. In this situation, the driver 13 has continued its path along the circular path 14 and has already retracted the weft thread 5 a short distance. The fixing element 11 remains in the fixing position I.

[0057] In Figure 7 Another situation is shown when retracting the weft thread 5, in which the weft thread 5 is now almost completely retracted. This situation corresponds to the representation of the Figure 3 .

[0058] In Figure 7Furthermore, a retraction area RB for the driver 13 is shown. According to an advantageous embodiment of the retraction device 9 according to the invention, the driver 13 is driven discontinuously and is driven at a reduced speed in the retraction area RB. If the driver 13 is located in the retraction area RB, it does not interfere with the unwinding of the turns during weft insertion. It is also possible for the driver 13 to be temporarily stopped in a rest position (not shown) which is located at the beginning of the retraction area RB. In this case, the weft thread 5 remains connected to the driver 13, which is stopped in the rest position RP, until the weft insertion. This can be advantageous for releasing the weft thread 5 and for the start of the weft insertion. However, the discontinuous driving and stopping in the rest position are not absolutely necessary. It is also conceivable to allow the driver 13 to rotate continuously.

[0059] In Figure 8 Now, another situation is shown in which the weft insertion has just started and the weft thread 5 is just releasing from the driver 13. The driver 13 is located at this moment in a release position AGP. For the weft insertion, the fixing element 11 was moved from the fixing position I to the release position II, whereby the weft thread 5 was released for the weft insertion. The weft thread 5 accelerated by the main nozzle 20 thereby begins to expand, forming a thread balloon 21 (see Figures 9 and 11) in an unwinding direction AR from the drum 8 and is subsequently inserted into the shed 2. The unwinding direction AR corresponds to the direction of rotation of the driver 13 and thus, according to the present illustration, also occurs counterclockwise. Due to the resulting centrifugal forces and the unwinding movement in the unwinding direction AR, the weft thread 5 now begins to detach itself from the driver 13.

[0060] Depending on the design of the retrieval device, the release of the weft thread 5 can be assisted as previously described by temporarily stopping the driver 13.

[0061] The delivery position AGP also defines the beginning of the retraction area RB, in which the driver 13 moves away from the drum 8 after the weft thread 5 is released. The delivery position AGP is variable and, if necessary, adjustable. It depends, for example, on the degree of retraction of the weft thread 5, but remains essentially unchanged within a weaving process with the same machine settings.

[0062] Figure 9 shows another situation during weft insertion. The weft thread 5 has meanwhile completely detached itself from the driver 13 and is being drawn into the shed 2 (see Figures 1-3 ) is entered. The fixing element 11 is still in the release position II. The driver 13 has meanwhile been accelerated again and has continued its path on the circular path 14 in order to return to the pick-up position AP.

[0063] According to an alternative embodiment of the return device 9 and the method, however, it is also possible for the driver 13 to remain stationary in the already described rest position during the weft insertion or, after a short further movement on the circular path 14, in a further rest position in order not to disturb the weft insertion.

[0064] Subsequently, a piece of the weft thread 5 can then be applied again in turns to the drum 8. Likewise, the fixing element 11 can then be moved again from the release position II to the fixing position I in order to fix the weft thread 5 on the drum 8. Subsequently, the driver 13 continues its path back to the pick-up position AP, where it can once again grasp the weft thread 5, which is now again stretched between the fixing element 11 and the balloon limiter 12.

[0065] Like the Figures 4-10can be removed, the driver 13 has a comparatively long catching contour 27, by means of which it can easily grasp the weft thread 5. Since the catching contour 27 is also inclined in the direction of the rotational axis 16 of the driver, grasping the weft thread 5 is further facilitated. The weft thread 5 can thus be reliably grasped even with different diameters DT of the drum 8.

[0066] In the example shown here, the diameter DK of the circular path 14 of the driver 13 is slightly larger than the diameter DT of the drum 8. This can assist in the secure gripping of the weft thread 5 in the pick-up position AP. At the same time, in conjunction with the longer catching contour 27, this can also assist in the secure pick-up of the weft thread 5 even with different diameters DT of the drum 8.

[0067] According to the example shown here, the axis of rotation 16 of the driver 13 and the axis 17 of the drum 8 are offset from one another by an axial offset A. Due to this axial offset A, the circular path 14 of the driver 13 is located in the area of ​​the pick-up position AP and thus in the area of ​​the fixing element 11, close to the diameter DT of the drum 8. On the side of the drum 8 facing away from the fixing element 11 or the pick-up position AP, however, the circular path 14 of the driver 13 is at a greater distance from the diameter DT of the drum 8. This allows the driver 13 to easily grip the weft thread 5 in the pick-up position AP. However, the driver 13 then moves away from the drum 8 and thus does not interfere with the unwinding of the turns from the drum 8.

[0068] A particular advantage of the described retrieval device 9 is that the weft thread 5 releases itself automatically from the driver 13. Thus, no active release elements are required for weft insertion in the retrieval device 9. Weft insertion disruptions caused by an incorrectly timed release of the weft thread 5 are thus avoided. Likewise, a sudden release of excessive weft thread lengths and the resulting weft insertion disruptions cannot occur. It is also particularly advantageous that, in the described retrieval device 9, the weft thread 5 is not subjected to any frictional influences from guide elements or the like during weft insertion.

[0069] The present invention is not limited to the illustrated and described embodiments.

[0070] Thus, even if a pneumatic weft thread insertion system 4 is shown here, the described retrieval device 9 can in principle also be used in conjunction with other weft thread insertion systems 4.

[0071] Further modifications within the scope of the patent claims are possible, as is any combination of the described features, even if they are shown and described in different parts of the description or the claims or in different embodiments, provided that no contradiction with the teaching of the claims arises. List of reference symbols

[0072] 1 Loom 2 Shed 3 Warp threads 4 Weft insertion system 5 Weft thread 6 Weft supply 7 Prewinding device 8 Drum 9 Retrieval device 10 Reed 11 Weft thread fixing element 12 Balloon limiter 13 Driver 14 Circular path 15 Drive 16 Driver rotation axis 17 Drum axis 18 Ring 19 External toothing 20 Main nozzle 21 Thread balloon 22 Suction nozzle 23 Deflection nozzle 24 Weft insertion channel 25 Separating device 26 Gear 27 Catch contour 28 Thread guide element I Fixing position II Release position RB Retraction area AP Pick-up position AGP Delivery position DK Diameter of the driver's circular path DT Diameter of the drum A Axis offset AR Unwinding direction ES Insertion side SR Weft insertion direction WRDirection of goods withdrawal

Claims

1. A method for inserting and retracting a weft thread (5) on a weaving machine (1), in particular an air jet weaving machine, in which a weft thread (5) to be inserted is intermediately stored on a drum (8), wherein during the intermediate storing the weft thread (5) is fixed on the drum (8) by a fixing element (11) located in a fixing position (I), the weft thread (5) is released for the weft insertion, wherein the fixing element (11) is moved from the fixing position (I) into a releasing position (II), and the weft thread (5), forming a thread balloon (21), is unwound from the drum (8) in an unwinding direction (AR) and is inserted, and in which the weft thread (5) is retracted by means of a retracting device (9) after the weft insertion has taken place, wherein the weft thread (5) is gripped in a pick-up position (AP) after the fixing element (11) and in the region of the thread balloon (21) and retracted, wherein the weft thread (5) is gripped by a carrier (13) of the retracting device (9) which can be moved along a circular path (14) around the drum (8) and is retracted by the further movement of the carrier (13) along the circular path (14), characterized in that the carrier (13) is moved in a rotating manner along the circular path (14).

2. The method according to the preceding claim, characterized in that the weft thread (5) is retracted by the retracting device (9) into a main nozzle (20) of a pneumatic weft thread insertion system (4) of the weaving machine (1) in such a way that the weft thread (5) is still located in the blowing region of the main nozzle (20) after the retraction.

3. The method according to claim 1 or 2, characterized in that the carrier (13) is driven discontinuously along the circular path (14), wherein the carrier (13) is moved in a rotating manner and periodically between the pick-up position (AP) and a discharging position (AGP), in which the weft thread (5) is discharged again.

4. The method according to one of claims 1 - 3, characterized in that the carrier (13) is moved in a rotating manner from the pick-up position (AP) via a retraction region (RB) again into the pick-up position (AP) and wherein the carrier (13) is moved at a reduced speed and / or is temporarily stopped after retracting the weft thread (5) in the retraction region (RB).

5. The method according to one of claims 1 - 4, characterized in that the carrier (13) grips the weft thread (5) directly after the fixing element (11) with respect to the thread path and / or that the carrier (13) grips the weft thread (5) in front of a thread guiding element (28) following the drum (8) with respect to the thread path.

6. The method according to one of claims 4 - 5, characterized in that the weft thread (5) remains connected to the carrier (13) located in the retraction region (RB) until the following weft insertion.

7. The method according to one of claims 1 - 6, characterized in that the carrier (13) is driven in a rotating manner along the circular path in the unwinding direction (AR) of the weft thread (5).

8. The method according to one of claims 1 - 7, characterized in that after releasing the weft thread (5) for the weft insertion by the fixing element (11), the weft thread (5) is automatically released from the carrier (13) by the thread tensile force and centrifugal force acting on it during the weft insertion.

9. The method according to one of claims 1 - 8, characterized in that after releasing the weft thread (5) for the weft insertion, the carrier (13) is accelerated and is moved further into the pick-up position (AP).

10. The method according to one of claims 1 - 9, characterized in that after releasing the weft thread (5) from the carrier (13), the carrier (13) is accelerated and is moved further into the pick-up position (AP).

11. The method according to one of the preceding claims, characterized in that the weft thread (5) runs unguided through the retracting device (9) during the weft insertion.

12. The method according to one of the preceding claims, characterized in that the weft insertion is started before a weft thread insertion channel (24) of the weaving machine (1) is released from the opening weaving shed (2).

13. A pre-winding device (7) for a weaving machine (1), in particular an air jet weaving machine, having a drum (8) for intermediate storing a weft thread (5) to be inserted, having a fixing element (11) for the weft thread (5), which is assigned to the drum (8) and which can be moved from a fixing position (I) into a releasing position (II) for releasing the weft thread (5) for the weft insertion, and having a retracting device (9) for retracting the weft thread (5) after the weft insertion has taken place, wherein the retracting device (9) is arranged in the pre-winding device (7) in the thread path after the fixing element (11), and in that the retracting device (9) has a carrier (13) for the weft thread (5), which carrier grips the weft thread (5) in a pick-up position (AP) after the fixing element (11) and in the region of a thread balloon (21) forming during the weft insertion, characterized in that the carrier (13) can be moved in a rotating manner along a circular path (14) around the drum (8).

14. The pre-winding device (7) according to the preceding claim, characterized in that the retracting device (9) has a drive (15) for driving the carrier (13).

15. The pre-winding device (7) according to one of claims 13 or 14, characterized in that the carrier (13) can be moved discontinuously along the circular path (14) from the pick-up position (AP) via a retraction region (RB) again into the pick-up position (AP).

16. The pre-winding device (7) according to one of claims 13 - 15, characterized in that the retracting device (9) is arranged in the pre-winding device (7) in such a way that the pick-up position (AP) is located directly after the fixing element (11) in the thread path.

17. The pre-winding device (7) according to one of claims 13 - 16, characterized in that the carrier (13) is designed as an open hook.

18. The pre-winding device (7) according to one of claims 13 - 17, characterized in that a diameter (DK) of the circular path (14) of the carrier (13) is greater than a diameter (DT) of the drum (8).

19. The pre-winding device (7) according to one of claims 13 - 18, characterized in that an axis of rotation (16) of the carrier (13) has an axial offset (A) with respect to an axis (17) of the drum (8).

20. The pre-winding device (7) according to one of claims 13 - 19, characterized in that the retracting device (9) has an externally toothed ring (18), on which the carrier (13) is arranged and which can be driven by means of the drive (15).

21. A weaving machine (1), in particular an air jet weaving machine, having a weft thread insertion system (4) and a pre-winding device (7) according to one of claims 13 - 20.

22. The weaving machine (1) according to the preceding claim, characterized in that the weft thread insertion system (4) is designed as a pneumatic weft thread insertion system (4) having at least one main nozzle (20).