Method for inserting and returning weft yarn in an air jet loom, feeder for an air jet loom, and air jet loom
The method for weft yarn insertion and retraction in air jet looms using a drum and downstream return device addresses yarn damage by minimizing exposure to damaging airflow, allowing earlier start-up for efficient and reliable insertion.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- LINDAUER DORNIER GMBH
- Filing Date
- 2022-06-03
- Publication Date
- 2026-06-08
AI Technical Summary
In air jet looms, weft yarns are often damaged due to pressure pulsation at the yarn starting point in the main nozzle, leading to fabric defects, and existing solutions either increase yarn length or position return devices in ways that cause friction or require complex adjustments.
A method and feeder for air jet looms that involve intermediate storage of weft yarns on a drum, using a movable fixing member to release the yarn for insertion, forming a yarn balloon, and then retracting it with a return device positioned downstream, capturing the yarn within the balloon area to minimize damage.
The method reduces yarn damage by ensuring only a short portion is exposed to damaging airflow, minimizing waste and enabling earlier yarn start-up for faster, more reliable insertion with reduced complexity and space requirements.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a method for inserting and retracting weft yarns in a loom, particularly an air jet loom, which involves intermediate storage of the weft yarns to be inserted on a drum, fixing the weft yarns on the drum by a fixing member located at a fixed position during intermediate storage, releasing the weft yarns for weft insertion, at which time the fixing member is moved from the fixed position to the release position, paying out the weft yarns from the drum in the pay-out direction while forming a yarn balloon for insertion, and after the weft insertion, retracting the weft yarns by a retracting device. Further, the present invention relates to a feeder for a loom and a loom.
[0002] Methods and devices for inserting and retracting weft yarns are well-known in various configurations in a loom. For example, a weft retracting device for tensioning the weft yarn after insertion is well-known.
[0003] Furthermore, in a repair loom, it is well-known that the weft yarn end in front of the repair is retracted again by a small distance by a retracting device before being captured by the repair. For this purpose, a finger is pivoted into the path of the weft yarn by an operating lever, and now the shortened weft yarn end is placed in front of the repair. Such a yarn retracting unit is shown, for example, in German Patent Application Publication No. 3524727.
[0004] In the case of an air jet loom, on the other hand, there frequently occurs a problem that the weft yarn end is damaged over a relatively large length due to pressure pulsation at the yarn starting point in the main nozzle. In this case, these damages are also recognized as fabric defects in the finished woven fabric. Therefore, in order to avoid this, in an air jet loom, frequently, the length of the weft yarn is increased until the damage caused to the weft yarn by compressed air advances again from the shed on the right side of the woven fabric and reaches the waste section on the right side.
[0005] U.S. Patent No. 3,370,618 proposes a supply and measuring device for precisely setting the length of the weft to be inserted. Furthermore, it is desirable that this device also be able to pull the end of the weft back into the nozzle. This is done using a linearly moving tube, in which case the thread is held by a clamping member.
[0006] German Patent Application Publication No. 10210911 proposes pulling the weft yarn back from the blowing area of the main blowing nozzle after the completion of weft insertion. For this purpose, a return device is positioned between the feeder and the main blowing nozzle. The return device has a swivel arm equipped with a deflection member for the weft yarn. After being returned, the weft yarn remains taut due to the suction action of the main blowing nozzle, and the weft end is not exposed to an extremely strong, damaging blowing airflow. This also reduces damage to the woven fabric. In addition, the return unit can also act as a yarn brake to slow the weft yarn near the end of weft insertion.
[0007] In both the case of West German Patent Application Publication No. 3524727 and Swedish Patent Invention No. 154756, a finger equipped with a pin is rotated within the path of the weft thread to pull the weft thread back. The pin is then actively pulled back to release the weft thread again. This return device is also positioned between the nozzle and the feeder.
[0008] Similarly, International Publication No. 2005 / 064059 also describes a return device positioned immediately after a funnel-shaped balloon limiter. This device can also function as both a yarn brake and a return device. However, when the yarn is accelerated within the main nozzle, damage to the weft still occurs, which degrades the quality of the woven fabric.
[0009] The object of this invention is to propose a method for inserting and returning weft threads that avoids damage to the woven fabric and enables improved weft insertion. Furthermore, the invention aims to propose a corresponding feeder and a loom equipped with such a feeder.
[0010] This problem is solved by a method, feeder, and loom having the features described in the independent claim.
[0011] In a loom, particularly an air-jet loom, the method for inserting and returning the weft yarn involves intermediate storage of the weft yarn to be inserted on a drum. During intermediate storage, the weft yarn is fixed on the drum by a fixing member located in a fixed position. The weft yarn is released for insertion, at which point the fixing member is moved from the fixed position to the release position, and the weft yarn is fed out from the drum in the feeding direction, forming a yarn balloon, and inserted. After the weft yarn has been inserted, it is pulled back by a return device.
[0012] We propose capturing and retracting the weft thread at a pull-in position downstream of the fixing member and within the area of the thread balloon.
[0013] Similarly, in a feeder for a loom, particularly an air-jet loom, comprising a drum for intermediate storage of weft yarn to be inserted, a fixing member for the weft yarn that is movable from a fixed position to a released position and positioned in correspondence with the drum, and a return device for pulling back the weft yarn after it has been inserted, the return device is positioned downstream of the fixing member in the yarn path, and the return device has a guide body for the weft yarn, which captures the weft yarn at a pull-in position downstream of the fixing member and within the area of the yarn balloon formed when the weft yarn is inserted.
[0014] By using the return device to pull back the weft, it is now possible to pull the weft back to such an extent that only a relatively short portion remains in the main nozzle. Now, even if this very short portion is damaged by compressed air during the acceleration of the weft in the main nozzle, this is no longer a problem, because this short portion will inevitably reach the waste section on the right side anyway.
[0015] Furthermore, by positioning the return device to the feeder downstream of the fixed member in the thread path, an extremely compact unit requiring minimal configuration space can be provided. Moreover, based on this arrangement, the weft thread, stretched between the drum and the thread guide member following the drum (such as a balloon limiter) after weft insertion, can be reliably captured between the fixed member in contact with the drum and the thread guide member. In other words, it is unnecessary to continuously guide the weft thread in the return device, even during weft insertion. This helps to avoid weft insertion errors. By capturing the weft thread immediately downstream of the fixed member in the thread path, the weft thread can be pulled back particularly effectively, and for this purpose, a return device equipped with a circumferentially moving guide body is used. It will be done .
[0016] The advantages of the present invention are also effective in weft insertion systems and corresponding looms equipped with such feeders, particularly air-jet looms, and therefore, protection is also claimed for these.
[0017] A further advantage is when the weft is pulled back by a return device into the main nozzle of the loom's pneumatic weft insertion system. In this loom, it is advantageous that the weft insertion system is configured as a pneumatic weft insertion system with at least one main nozzle. In this case, the weft is pulled back so that it is barely within the blowing area of the main nozzle after it has been pulled back. This ensures that the weft is securely held by the retaining air of the main nozzle, while preventing significant damage to the weft end from the retaining air before weft insertion. By pulling the weft back only to the extent that its end is still within the blowing area of the main nozzle, damage to the weft due to acceleration within the main nozzle is limited to a very short portion of the yarn path located before the injector of the main nozzle. The main nozzle generally has a mixing tube and an injector, as shown, for example, in German Patent Invention No. 10224078, by which compressed air is brought into the mixing tube. This extremely short portion of the weft yarn reappears in the waste or captured strip on the right side after weft insertion, and therefore does not impair the quality of the fabric. Thus, increasing the length of the weft yarn and thereby producing an unnecessarily large amount of waste is no longer required.
[0018] In this invention The weft thread moves in a circular orbit around the drum. In the circumferential direction It is captured by a movable guide body of the return device and pulled back by the guide body continuing to move along a circular orbit. In the return device, the guide body moves along a circular orbit around the drum. In the circumferential directionIt is movable. For this reason, the return device advantageously has a drive mechanism that drives the lead body. This allows the return device to be constructed in a very simple manner. The yarn can be captured in a reliable process by the lead body, always at the same take-up position near the drum, for this reason no time-consuming adjustment work is required. Based on a relatively simple technical configuration, the return device is also suitable as a post-installation configuration for various looms.
[0019] In one advantageous configuration of the return device, it is further advantageous that the guide body is formed as an open hook. Using the open hook, the weft thread stretched between the fixing member and the subsequent thread guide member, such as a balloon limiter, can be captured particularly reliably.
[0020] It is also advantageous when the lead unit is driven discontinuously on a circular orbit. In this case, the lead unit is periodically moved between a take-up position and a delivery position where the weft is delivered again. In this case, the lead unit captures the weft at the take-up position in each weaving cycle, delivers the weft again at the delivery position, and then returns to the take-up position, thereby capturing and pulling back the weft for the subsequent weaving cycle.
[0021] In one advantageous configuration, the lead body is moved circumferentially on a circular orbit, in which case the lead body is returned from the take-up position through the retraction region to the take-up position, in which case the lead body is moved at a reduced speed within the retraction region and / or temporarily stopped after the weft is retracted. Correspondingly, it is advantageous for the return device if the lead body can move discontinuously on a circular orbit, returning from the take-up position through the retraction region to the take-up position. For this purpose, the return device may have a stepper motor or a servo motor as the drive device. The retraction region may be used, for example, to keep the lead body out of range that would affect the forming yarn balloon during weft insertion, for which the lead body is driven at a reduced speed. In this case, the lead body may be temporarily stopped at a resting position located within the retraction region. Temporary stopping of the lead body can also be used to keep the lead body out of range that would affect the forming yarn balloon during weft insertion. However, in one alternative configuration, the resting position may still be used to securely hold the weft thread attached to the lead body and to position the weft end at a desired position within the main blowing nozzle. In this case, it is conceivable to have two different resting positions for the lead body.
[0022] However, in one alternative configuration, continuous driving of the train is also possible without deceleration within the retraction region or without stopping at the resting position.
[0023] A particular advantage is gained when the guide body captures the weft thread immediately after the fixed member with respect to the thread path. Similarly, in a return device, it is advantageous when the return device is positioned within the feeder such that the take-up position is located immediately after the fixed member in the thread path. Preferably, the guide body captures the weft thread 1 mm to 50 mm away from the fixed member. At this position, the weft thread can be captured particularly well by the guide body. Furthermore, by capturing the weft thread early in the thread path near the fixed member with a return device that moves circumferentially, a particularly large distance can be pulled back, and this is particularly effective.
[0024] Alternatively or additionally, it is advantageous if the carrier captures the weft thread in front of the thread guide member following the drum with respect to the thread path. As already mentioned, this enables particularly good capture of the weft thread. Furthermore, in this arrangement, there is no need for a thread guide member within the retractor device that could impede weft insertion based on its frictional effect. The weft thread is sufficiently guided between the drum or the fixed member and the subsequent thread guide member, such as the main nozzle.
[0025] In another advantageous configuration, the weft thread remains attached to the carrier located within the retraction region until the next weft insertion. In this case, as described above, the weft thread attached to the carrier is securely held in place, and the end of the weft thread is securely positioned at the desired location within the main blowing nozzle. If the carrier moves within the retraction region and cannot be stopped, the carrier will move at a low speed in any case. Furthermore, when moving on a circular path, the distance of the carrier from the fixed member within the retraction region increases only very slightly, so that the weft thread hardly changes its position any further even if the carrier continues to move. [[ID=?]]
[0026] In this method, it is particularly advantageous if the carrier is driven in the weft feed direction. This makes it easier to remove the weft thread from the carrier for the next weft insertion.
[0027] Therefore, it is also particularly advantageous if the weft thread automatically detaches from the carrier after being released by the fixed member for weft insertion, due to the thread tension and centrifugal force acting on the weft thread during weft insertion. That is, it can be detached solely by the balloon-like pay-out movement of the weft thread. However, detaching the weft thread from the carrier can additionally be assisted, as already mentioned above, by stopping the carrier at the rest position. However, there is no need to control an active member for release. Since the weft thread automatically detaches from the carrier without active control during weft insertion, there will be no delay or untimely release by the retractor device during weft insertion.
[0028] It is advantageous if the carrier is accelerated after the weft yarn has been released for weft insertion and is subsequently moved to the take-up position. That is, during weft insertion, the carrier continues its circular movement and quickly returns to the take-up position, whereby the next weft yarn can be captured and pulled back at the take-up position. In this case, it is particularly advantageous if the carrier is accelerated only after the weft yarn has detached from the carrier or, if the carrier has been stopped, is moved again and subsequently moved to the take-up position. Thereby, it is possible to assist the detachment of the weft yarn from the carrier. Furthermore, thereby, the carrier can be well retained outside the range affecting the yarn balloon being formed, without disturbing the weft insertion.
[0029] It is advantageous if the weft yarn extends without being guided by a retraction device during weft insertion. Thereby, the weft yarn extends freely between the drum and the subsequent yarn guiding member during weft insertion and thus is not affected by friction that could impair the weft insertion. Thereby, the weft insertion can be carried out more reliably and more quickly.
[0030] In one particularly advantageous refinement of the method, the weft insertion has already started before the weft insertion passage of the loom is released by the shed. For example, the weft insertion already starts at a loom angle of less than 50°, preferably less than 40°, particularly preferably less than 35°. Due to the weft yarn being retracted very substantially into the main nozzle by the retraction device, the weft yarn can be started earlier than is customary in the prior art. Thereby, the weft insertion can be accelerated, so that optionally an economical weft insertion using a relatively high rotational speed or a relatively low pressure is possible. Furthermore, by starting the yarn earlier, the leading end of the weft yarn already has a high speed when leaving the main nozzle, so that the leading end of the yarn is stably projected and thus a more reliable weft insertion is possible.
[0031] In a return device, it is even more advantageous if the diameter of the lead body's circular orbit is larger than the diameter of the drum. This helps to ensure secure capture of the weft at the take-up position. Preferably, the lead body has a slightly elongated capture contour that is directed from the diameter of the lead body's circular orbit toward the center of the lead body's circular orbit. This allows the return device to cover a variety of drum diameters.
[0032] Similarly, it is advantageous if the circumferential axis of the connecting body is offset from the axis of the drum. This allows the connecting body to pick up the weft thread well at the take-up position without interfering with subsequent weft thread insertion.
[0033] Therefore, the axial misalignment is particularly advantageous in combination with the larger diameter of the circular trajectory of the connecting body described above. This allows the connecting body to be brought particularly close to the circumferential surface of the drum at the take-up position, thereby enabling it to capture the weft. However, after the weft is released from the connecting body, the connecting body moves away from the circumferential surface of the drum and therefore does not hinder the unwinding of the weft.
[0034] A further advantage is when the return device has a ring with teeth on its exterior, on which a guide body is positioned, and the ring is driveable by a drive mechanism. This makes it possible to position the return device directly on the feeder, for example, directly on the balloon limiter of the feeder. In this case, the yarn path may, particularly advantageously, pass inside the ring. As a result, the weft yarn engages with the return device only during return, but does not engage during weft insertion, and extends through the inside of the ring. This eliminates the need for an active release member that must be controlled by the loom control device, which also contributes to avoiding weft insertion errors.
[0035] Other advantages of the present invention are described in the following examples. [Brief explanation of the drawing]
[0036] [Figure 1] This is a schematic diagram showing a loom with a feeder equipped with a return device in its first state immediately after weft insertion. [Figure 2] This is a schematic diagram showing the loom shown in Figure 1 in a second state, after the weft threads have been inserted and cut. [Figure 3] This is a schematic diagram showing the loom shown in Figure 1 in the third state after the weft thread has been pulled back. [Figure 4] This is a schematic diagram showing the drum of a feeder equipped with a return device, as seen from the shuttle opening, when capturing the weft thread in the first state. [Figure 5] This is a schematic diagram showing the drum shown in Figure 4 when the weft thread is pulled back in the second state. [Figure 6] This is a schematic diagram showing the drum shown in Figure 4 when the weft thread is pulled back in the third state. [Figure 7] This is a schematic diagram showing the drum shown in Figure 4 after the weft thread has been pulled back in the subsequent state. [Figure 8] This is a schematic diagram showing the drum used when removing the weft thread in the subsequent state, as shown in Figure 4. [Figure 9] This is a schematic diagram showing the drum shown in Figure 4 during the subsequent insertion of the weft thread. [Figure 10] This is a schematic diagram showing the return device and balloon limiter as seen from the weft reservoir. [Figure 11] This is a schematic diagram showing one alternative configuration of a loom having a feeder equipped with a return device during weft insertion.
[0037] In the following description of the embodiments, the same reference numeral is used for identical features, or for features that are at least equivalent in their configuration and / or mode of operation. Furthermore, these are described in detail only when they are first mentioned, whereas in the following embodiments, only the differences from the embodiments already described are described. In addition, for ease of reading, often only one or a few of several identical components or features are given reference numerals.
[0038] Figure 1 shows a schematic diagram of a loom 1 having a feeder 7 equipped with a return device 9, in a first state immediately after weft insertion. The loom 1 typically has a weft reservoir 6 on the insertion side ES, from which the weft yarn 5 is unwound and supplied to the feeder 7. The feeder 7 has a drum 8, on which the weft yarn 5 is wound multiple times by a winding disc (not shown) and piled up. In this embodiment, the weft yarn 5 passes from the drum 8 through a balloon limiter 12 and proceeds to the weft insertion system 4 of the loom 1. The weft insertion direction SR is indicated by an arrow. A cutting device 25 is further located on the insertion side ES to cut the weft yarn 5 after weft insertion.
[0039] The weft yarn 5 wound on the drum 8 is held there by a fixing member 11. The fixing member 11 is positioned in a fixed position I (see Figures 4-9) to hold the weft yarn 5 and can be moved to a released position II (see Figures 4-9) to release the weft yarn 5. The fixing member 11 is formed, for example, as a retractable pin that can be fed into the drum 8. Then, for weft insertion, the fixing member 11 is moved to the released position II, and a predetermined number of weft yarn 5 wounds are drawn out from the drum 8 during weft insertion. In this case, the number of wounds drawn out can be detected by a sensor, so that a predetermined number of wounds are always drawn out in a single weft insertion. After weft insertion is complete, the fixing member 11 is returned to the fixed position I.
[0040] The weft insertion system 4, in this embodiment, is pneumatically formed and includes a main nozzle 20 located on the insertion side ES of the loom 1 in a known manner. In this embodiment, only one main nozzle 20 is illustrated. However, it is also possible and common for two main nozzles 20 to be located one behind the other on the insertion side ES. Compressed air can be supplied to the main nozzle 20. In this case, a relatively weak airflow, so-called holding air, can be supplied to the main nozzle 20 to hold the weft 5 until the next weft insertion. Conversely, a relatively strong airflow, so-called main air, can be supplied to the main nozzle 20 for weft insertion. This accelerates the end of the weft 5 and inserts it into the open shuttle 2. The shuttle 2 is generally formed by alternately raising and lowering a plurality of adjacent warp threads 3. After weft insertion has been performed, the weft 5 is driven in by the reed 10, also in a known manner. In the air-jet loom shown here, the reed 10 has a weft insertion passage 24 into which the weft yarn 5 is introduced by a main nozzle 20 and transported through the shuttle 2 within the weft insertion passage 24. For this purpose, the weft insertion system 4 includes a plurality of relay nozzles (not shown here) distributed across the reed 10, which assist in the transport of the weft yarn 5 through the shuttle 2. On the side of the loom 1 opposite to the insertion side ES, the weft insertion system 4 further has a suction nozzle 22, which captures and supports the inserted weft yarn 5. In this state shown in this embodiment, the weft yarn 5 is just inserted and supported by the suction nozzle 22. In the case of the loom 1 of this embodiment, a deflection nozzle 23 is also provided. The deflection nozzle 23 uses airflow to draw the weft yarn 5 protruding from the shuttle opening 2 back out through the suction nozzle 22, moving the weft yarn 5 in the product extraction direction WR. Therefore, the weft yarn 5 protruding from the shuttle opening 2 does not obstruct the subsequent insertion of the weft yarn.
[0041] In such a pneumatic weft insertion system 4, the weft yarn 5 is often damaged at the yarn starting point by acceleration within the main nozzle 20. This problem occurs particularly with untwisted filament yarns. In this case, these damages are often visible as defects in the finished fabric. These problems can also occur with core yarns. Therefore, in the prior art, the weft length is often increased, which carries the damaged portion, mainly at the weft end, through the shuttle 2 and discharges it as a weft waste on the right side of the loom 1, opposite the insertion side ES. Similarly, in the prior art, a return device 9 is already used to pull the weft yarn 5 back from the blowing area of the main nozzle. In this case, the weft yarn 5 is indeed kept under tension by the main nozzle 20, but the weft end is no longer damaged by the strong airflow.
[0042] In the case of the loom 1 of this embodiment, such a return device 9 for returning the weft 5 after it has been inserted is located between the drum 8 and the balloon limiter 12. The return device 9 has a dedicated drive unit 15. The exact function of the return device 9 will be described in more detail with reference to Figures 4 to 9. In this case, it is obvious that a dedicated feeder 7 with a dedicated return device 9 is provided for each color.
[0043] However, the balloon limiter 12 is not necessarily required. In one alternative configuration of the loom shown in Figure 11, only the yarn guide member 28 is located downstream of the feeder 7. The yarn guide member 28 may be located directly on the feeder 7. The yarn guide member 28 may be formed, for example, as a ceramic hole. Figure 11 shows the loom 1 during weft insertion. In this case, it is also clear that the weft 5 is fed out of the drum 8 while forming a yarn balloon 21. In other respects, this loom 1 corresponds to the one shown in Figure 1.
[0044] Figure 2 shows the loom 1 shown in Figure 1 in a second state after weft insertion and cutting of the weft 5. As is clear, in this state, the weft 5 has already been cut at the insertion side ES. Similarly, the weft end has already been redirected in the product extraction direction by the deflection nozzle 23 on the side opposite to the insertion side ES. At this time, the weft end that was cut at the insertion side ES of the loom 1 protrudes slightly beyond the end of the main nozzle 20.
[0045] Figure 3 further shows the loom 1 shown in Figure 1 in a third state after the weft 5 has been pulled back. In the interval after weft insertion, the fixing member 11 is brought back from the release position II to the fixing position I, where it fixes the weft 5 wound around the drum 8. The return device 9 then pulls back the now fixed weft 5. As can be seen from Figure 3, in this case, the weft 5 in the main nozzle 20 is pulled back to the extent that only a very short portion remains inside the main nozzle 20. In this case, the weft 5 is pulled back to the extent that it is still within the blowing area of the main nozzle 20, that is, still in front of the opening of the injector (not shown). This pull-back of the weft 5 means that when the weft 5 is accelerating, only a very short portion of it is exposed to the damaging effect of the main air. However, severe damage to this very short portion is not a problem because an unavoidable right-side waste portion is always generated due to the process. This very short portion, after weft insertion, is located within the inevitable right-side waste section and is disposed of together with this waste section. Based on further pulling back of the weft 5, the damaged weft end will again separate from the shuttle 2 on the opposite side from the insertion side, and therefore there is no risk of damaging the fabric.
[0046] However, this does not only result in a reduction of approximately 10-14 cm in the weft waste area on the right side. In particular, as can be seen in Figure 2, the weft end protruding beyond the shuttle 2 on the right side is extremely short, which achieves several other advantages. Specifically, for example, the shortened weft end significantly reduces the likelihood of blockage of the suction nozzle 22 and the deflection nozzle 23. Similarly, in the prior art, the long weft end protruding laterally frequently caused locking of the width holder (not shown). This, too, is avoided by the now significantly shorter weft end protruding laterally beyond the shuttle 2 or the product. Likewise, the problem of winding the captured strip (also not shown) on the right side can be avoided.
[0047] Furthermore, and particularly advantageously, by pulling the weft 5 back almost to the opening of the injector of the main nozzle 20, the weft is already accelerated within the main nozzle 20 and consequently flows out at high speed. As a result, the weft 5 leaves the main nozzle 20 in an extended state and at high speed, thus making it easier to insert into the weft insertion passage 24 of the reed 10. This leads to more stable weft insertion. Problems such as "stick formation," where a weft 5 positioned far behind overtakes the weft end in front, can also be avoided.
[0048] A further advantage is that, in this case, the weft yarn 5 can be started before the open shuttle 2 releases the weft insertion passage 24, because the weft yarn 5 is still located inside the main nozzle 20 at the time of yarn start-up. By the time the weft yarn end travels its path to the shuttle 2, the shuttle 2 is already fully open. Therefore, yarn start-up can be performed earlier, which allows for an increase in the rotational speed of the loom 1 and, consequently, an increase in production. For example, yarn start-up is already possible at a loom angle of approximately 30°.
[0049] Because the weft yarn 5 can be accelerated earlier, it has already reached almost its maximum speed by the time it reaches the shuttle 2. Therefore, it is advantageous that the weft insertion can be carried out at a lower air pressure, thereby enabling energy-efficient operation of the loom 1.
[0050] Interference in weft insertion that may be caused by retained air in adjacent main nozzles 20 is also avoided by pulling the yarn back into the main nozzles 20. The end of the weft yarn is still located inside the main nozzles 20 during acceleration or yarn initiation, and is therefore not obstructed by air vortices in adjacent main nozzles 20.
[0051] Next, the return device 9 and its functional form according to the present invention will be described based on Figures 4 to 10. In this case, Figures 4 to 9 show schematic plan views of the return device 9 and drum 8 of the feeder 7 as seen from the shuttle 2. In contrast, Figure 10 shows a schematic plan view of the return device 9 and balloon limiter 12 as seen from the weft reservoir 6.
[0052] As can be seen from Figure 10, the return device 9 has a weft guide body 13 that moves circumferentially on a circular orbit 14, and in this embodiment the guide body 13 is formed in the shape of a hook. In this embodiment the guide body 13 has a capture contour 27, and as will be further described below, the guide body 13 can capture the tensioned weft 5 by the capture contour 27. The guide body 13 is positioned on a rotatably supported ring 18, which is coupled to a gear 26 via an outer tooth row 19 and driven by this gear 26. The gear 26 itself is driven by a drive device 15, which is only hidden in the illustration here. The ring 18 with the outer tooth row rotates on a circular orbit 14 about the circumferential axis 16 of the guide body 13, and consequently the guide body 13 also moves circumferentially on a circular orbit 14 about the rotation axis 16 of the guide body 13. To enable controlled driving of the trainer 13, and, if assumed, discontinuous or intermittent driving, the drive unit 15 is preferably formed as a stepper motor. Inside the ring 18, which has a toothed row on the outside, the inner surface of the balloon limiter 12 can be seen. For reference, a drum 8 with a diameter DT of the feeder 7, which is not visible in this figure, is indicated by a dashed line. As can be seen from Figure 10, the trainer 13 also moves circumferentially around the drum 8. Furthermore, DK represents the diameter of the circular orbit 14 of the trainer 13.
[0053] However, as already mentioned with respect to Figure 11, the balloon limiter 12 is not necessarily required, and only the yarn guide member 28 may be provided. In any case, the functional form of the return device 9 is the same. In one other configuration of the return device 9, which is not shown here, the return device 9 has a capture hook attached to the driven shaft rather than a ring 18 with teeth on the outside. The capture hook rotates 360° around its own axis. In other respects, the functional principle of this configuration corresponds to that described with respect to Figure 10. Therefore, the following description with respect to Figures 4 to 9 clearly relates to various configurations of the return device 9 and the loom 1.
[0054] Next, the process of pulling back the weft thread 5 will be explained based on Figures 4 to 9.
[0055] In this case, Figure 4 shows the drum 8 equipped with the return device 9 as seen from the shuttle when capturing the weft 5 in the first state. This state corresponds to the state shown in Figure 2, when the weft 5 has just been cut after insertion. Similarly, in this state, the fixing member 11 has already been moved again from the release position II (see Figure 8) to the fixed position I after the weft insertion, and at the fixed position I, the fixing member 11 fixes the weft 5 on the drum 8. In this state, the guide body 13, which moves circumferentially on the circular orbit 14, is just at the take-up position AP, and at the take-up position AP, the guide body 13 captures the weft 5 stretched between the fixing member 11 and the balloon limiter 12 (see Figure 1). The balloon limiter 12 itself is not visible here and in Figures 5 to 9, but is located in front of the plane of the figure. In this example, the take-up position AP is located immediately after the fixing member 11 in the weft insertion direction. Therefore, the weft 5 can be captured particularly well by the guide body 13.
[0056] Figure 5 shows the second state when the weft thread 5 is being pulled back. In this state, the guide body 13 has already moved slightly counterclockwise on the circular orbit 14 from the take-up position AP, and at this time, the guide body 13's capture contour 27 picks up the weft thread 5. The weft thread 5 is now stretched between the fixing member 11, the guide body 13, and the balloon limiter 12 (or alternatively, the thread guide member 28). The weft thread 5 is fixed to the drum 8 by the fixing member 11, but the end of the weft thread is held movably within the main nozzle 20, so the weft thread 5 is now pulled back into the main nozzle 20 by further movement of the guide body 13.
[0057] Figure 6 shows the third state when the weft thread 5 is being pulled back. In this state, the connecting body 13 continues its journey on the circular orbit 14, and at this point, the weft thread 5 has already been pulled back a little further. The fixing member 11 remains in the fixed position I.
[0058] Figure 7 shows the subsequent state when the weft thread 5 is pulled back, in which case the weft thread 5 is now almost completely pulled back. This state corresponds to the diagram shown in Figure 3.
[0059] Figure 7 further shows a pull-back region RB for the connecting body 13. In one advantageous configuration of the return device 9 according to the present invention, the connecting body 13 is driven discontinuously and at a reduced speed within the pull-back region RB. When the connecting body 13 is located in the pull-back region RB, the connecting body 13 does not obstruct the unwinding of the winding when the weft is inserted. In this case, the connecting body 13 can also be temporarily stopped at a rest position (not shown) located at the beginning of the pull-back region RB. In this case, the weft 5 remains connected to the connecting body 13 stopped at the rest position RP until the weft is inserted. This may be advantageous with respect to the removal of the weft 5 and the initiation of weft insertion. However, discontinuous driving and stopping at the rest position are not necessarily required. It is also conceivable to advance the connecting body 13 continuously in the circumferential direction.
[0060] Next, in the subsequent state shown in Figure 8, weft insertion has just begun, and the weft 5 has just detached from the lead body 13. The lead body 13 is at the handover position AGP at this point. For weft insertion, the fixing member 11 is brought from the fixing position I to the release position II, thereby releasing the weft 5 for insertion. As a result, the weft 5, accelerated by the main nozzle 20, is fed out of the drum 8 in the feed direction AR, forming a yarn balloon 21 (see Figures 9 and 11), and then inserted into the shuttle 2. In this case, the feed direction AR corresponds to the circumferential direction of the lead body 13, and is therefore generated counterclockwise in this figure as well. Based on the centrifugal force generated at this time and the feed operation in the feed direction AR, the weft 5 now automatically begins to detach from the lead body 13.
[0061] Depending on the configuration of the return device, the removal of the weft thread 5 can be further assisted by the temporary stopping of the connecting body 13, as described above.
[0062] The handover position AGP simultaneously defines the start of the retraction region RB, in which the connecting body 13 separates from the drum 8 after the weft 5 has been released. The handover position AGP is variable and can be adjusted in some cases. The handover position AGP depends, for example, on the degree of retraction of the weft 5, but remains substantially constant for the same machine settings in a single weaving process.
[0063] Figure 9 shows the subsequent state during weft insertion. The weft 5 completely detaches from the guide body 13 in between and is inserted into the shuttle 2 (see Figures 1-3) while forming a thread balloon 21. Meanwhile, the fixing member 11 remains in the release position II. During this time, the guide body 13 is accelerated again and continues its journey on the circular orbit 14, thereby returning to the take-up position AP.
[0064] However, in one alternative configuration of the return device 9 and method, in order to avoid interfering with weft insertion, the guide body 13 can either remain stationary at the aforementioned resting position during weft insertion, or move a short distance further along the circular orbit 14 and then remain stationary at another resting position.
[0065] Next, a portion of the weft thread 5 can be newly wound onto the drum 8. Similarly, the fixing member 11 can then be moved again from the release position II to the fixing position I, thereby fixing the weft thread 5 on the drum 8. The guide body 13 then continues its process back to the take-up position AP, where it can again capture the weft thread 5 stretched between the fixing member 11 and the balloon limiter 12.
[0066] As can be seen from Figures 4 to 10, the connecting body 13 has a relatively long capture contour 27, which allows the connecting body 13 to capture the weft yarn 5 effectively. Furthermore, since the capture contour 27 is tilted toward the circumferential axis 16 of the connecting body, capturing the weft yarn 5 becomes even easier. This ensures that the weft yarn 5 is reliably captured even when the diameters DT of the drums 8 are different.
[0067] In the example shown here, the diameter DK of the circular orbit 14 of the guide body 13 is slightly larger than the diameter DT of the drum 8. This helps to ensure the secure capture of the weft 5 at the take-up position AP. At the same time, this also helps to ensure the secure pickup of the weft 5 in relation to the relatively long capture contour 27, even when the diameters DT of the drum 8 are different.
[0068] In the example shown here, the circumferential axis 16 of the connecting body 13 and the axis 17 of the drum 8 are further offset from each other by an axial misalignment A. Based on this axial misalignment A, the circular trajectory 14 of the connecting body 13 is located near the diameter DT of the drum 8 within the area of the take-up position AP and thus within the area of the fixing member 11. In contrast, on the side of the drum 8 opposite to the fixing member 11 or the take-up position AP, the circular trajectory 14 of the connecting body 13 has a larger gap with respect to the diameter DT of the drum 8. This allows the connecting body 13 to capture the weft 5 well at the take-up position AP. However, the connecting body 13 then moves away from the drum 8, thereby not hindering the unwinding of the yarn from the drum 8.
[0069] An advantage of the described return device 9 is that the weft 5 is automatically released from the connecting body 13. This eliminates the need for an active release member for weft insertion in the return device 9. This avoids weft insertion errors caused by the weft 5 being released prematurely. Similarly, there is no risk of abrupt release of excessively long weft and the resulting weft insertion errors. Furthermore, a particular advantage of the described return device 9 is that the weft 5 is not affected by friction from guide members or the like during weft insertion.
[0070] The present invention is not limited to the embodiments illustrated and described.
[0071] In other words, even though a pneumatic weft insertion system 4 is shown in the present invention, the return device 9 described can basically be used in conjunction with another weft insertion system 4.
[0072] Further modifications within the scope of the claims are permitted, provided that they do not contradict the teachings of the independent claims, as are any combinations of the described features, even if those features are illustrated and described in different parts of the specification or claims or in different embodiments. [Explanation of symbols]
[0073] 1. Loom 2 Shed 3 Warp threads 4. Weft insertion system 5 weft threads 6. Weft reservoir 7 feeders 8 drums 9. Return device 10 Reeds 11 Fixing member for weft thread 12 Balloon Limiter 13. Detainee 14 circular orbits 15 Drive unit 16. Circumferential axis of the trained body 17. Drum axis 18 rings 19 Lateral dentition 20 Main nozzle 21 String Balloons 22 Suction nozzle 23 Directional nozzle 24 Weft thread insertion passage 25 Cutting device 26 gears 27 Capture contour 28 Thread guide member I fixed position II Release position RB pullback area AP pickup location AGP handover location DK Aggregator's circular orbit diameter DT drum diameter A. Axis misalignment AR feed direction ES insertion side SR weft insertion direction WR Product Dispensing Direction
Claims
1. A method for inserting and returning a weft yarn (5) in an air jet loom, wherein the weft yarn (5) to be inserted is temporarily stored on a drum (8), the weft yarn (5) is fixed on the drum (8) by a fixing member (11) located at a fixed position (I) during temporary storage, the weft yarn (5) is released for insertion, the fixing member (11) is moved from the fixed position (I) to the released position (II), the weft yarn (5) is fed out from the drum (8) in the feeding direction (AR) while forming a yarn balloon (21) and inserted, and after the weft yarn insertion, the weft yarn (5) is pulled back by a return device (9), A method characterized in that the weft thread (5) is captured and pulled back at a take-up position (AP) downstream of the fixing member (11) and within the area of the thread balloon (21), at which time the weft thread (5) is captured by a guide body (13) of the return device (9) which is movable on a circular orbit (14) around the drum (8), and pulled back by the guide body (13) continuing to move on the circular orbit (14), the guide body (13) being moved circumferentially on the circular orbit (14).
2. The method according to claim 1, characterized in that the weft yarn (5) is pulled back by the return device (9) into the main nozzle (20) of the pneumatic weft insertion system (4) of the air jet loom, so that after being pulled back, the weft yarn (5) is barely located within the blowing area of the main nozzle (20).
3. The method according to claim 1 or 2, characterized in that the connecting body (13) is driven discontinuously on the circular orbit (14), and at this time, the connecting body (13) is periodically moved between the take-up position (AP) and the handover position (AGP) where the weft thread (5) is handed over again.
4. The method according to claim 1, characterized in that the connecting body (13) is moved circumferentially from the take-up position (AP) to the take-up position (AP) via the retraction region (RB), and at this time, the connecting body (13) is moved at a reduced speed within the retraction region (RB) and / or temporarily stopped after the retraction of the weft thread (5).
5. The method according to claim 1, characterized in that the connecting body (13) captures the weft thread (5) immediately after the fixing member (11) with respect to the thread path, and / or the connecting body (13) captures the weft thread (5) before the thread guide member (28) that follows the drum (8) with respect to the thread path.
6. The method according to any one of claims 4 to 5, characterized in that the weft (5) remains connected to the connecting body (13) located within the pull-back region (RB) until the next weft is inserted.
7. The method according to claim 1, characterized in that the connecting body (13) is driven circumferentially on the circular orbit (14) in the direction (AR) of the weft thread (5).
8. The method according to claim 1, characterized in that after the weft thread (5) is released by the fixing member (11) for the insertion of the weft thread, the weft thread (5) automatically detaches from the connecting body (13) due to the tensile force and centrifugal force acting on the weft thread (5) during the insertion of the weft thread.
9. The method according to claim 1, characterized in that after the weft (5) is released for the insertion of the weft, the connecting body (13) is accelerated and subsequently moved to the take-up position (AP).
10. The method according to claim 1, characterized in that after the weft thread (5) is detached from the connecting body (13), the connecting body (13) is accelerated and subsequently moved to the take-up position (AP).
11. The method according to claim 1, characterized in that the weft thread (5) extends without being guided by the return device (9) while the weft thread is being inserted.
12. The method according to claim 1, characterized in that the weft insertion is started before the weft insertion passage (24) of the air jet loom is opened by the open shuttle (2).
13. A feeder (7) for an air jet loom, comprising a drum (8) for intermediate storage of weft yarn (5) to be inserted, a fixing member (11) for the weft yarn (5) positioned corresponding to the drum (8) and movable from a fixed position (I) to a released position (II) to release the weft yarn (5) for insertion, and a return device (9) for pulling back the weft yarn (5) after insertion, The feeder (7) is characterized in that the return device (9) is located downstream of the fixing member (11) in the thread path, the return device (9) has a guide body (13) for the weft (5), the guide body (13) captures the weft (5) at a take-up position (AP) downstream of the fixing member (11) and within the area of the thread balloon (21) formed when the weft is inserted, and the guide body (13) is movable in the circumferential direction on a circular orbit (14) around the drum (8).
14. The feeder (7) according to claim 13, characterized in that the return device (9) has a drive device (15) for driving the connecting body (13).
15. The feeder (7) according to claim 13, characterized in that the accompanying body (13) is movable discontinuously on the circular orbit (14) so as to return from the take-up position (AP) to the take-up position (AP) via the return region (RB).
16. The feeder (7) according to claim 13, characterized in that the return device (9) is arranged within the feeder (7) such that the take-up position (AP) is located immediately after the fixing member (11) in the thread path.
17. The feeder (7) according to claim 13, characterized in that the connecting body (13) is formed as an open hook.
18. The feeder (7) according to claim 13, characterized in that the diameter (DK) of the circular orbit (14) of the connecting body (13) is greater than the diameter (DT) of the drum (8).
19. The feeder (7) according to claim 13, characterized in that the circumferential axis (16) of the connecting body (13) has an axial misalignment (A) with respect to the axis (17) of the drum (8).
20. The feeder (7) according to claim 13, wherein the return device (9) has a ring (18) having a toothed row on its outside, the accompanying body (13) is arranged on the ring (18), and the ring (18) is drivable by a drive device (15).
21. An air jet loom comprising a weft insertion system (4) and a feeder (7) according to any one of claims 13 to 20.
22. The air jet loom according to claim 21, characterized in that the weft insertion system (4) is formed as a pneumatic weft insertion system (4) equipped with at least one main nozzle (20).