SE1650986A1

SE1650986A1 - Weft yarn feeding arrangement with motor drive

Info

Publication number: SE1650986A1
Application number: SE1650986A
Authority: SE
Inventors: Johansson Birger; Josefsson Paer
Original assignee: Iro Ab
Priority date: 2016-07-06
Filing date: 2016-07-06
Publication date: 2018-01-07
Also published as: WO2018009119A1; EP3481979B1; EP3481979A4; EP3481979A1; CN109415850A; CN109415850B; EP3481979B8

Abstract

Described are, among other things, methods and devices for controlling a weft yarn feeding device (16) for feeding yarn to a weaving machine (10), wherein yarn is inserted into the shed of the weaving machine having at least one rapier. The weft yarn feeding device comprises at least one yarn guide (20) provided on a moving member (19) driven by a controlled motor (18) of the weft yarn feeding device to cause the moving member to move back and forth. When in use, yarn is drawn from a weft yarn storage (13, 14) via said at least one guide (20) provided on said moving member (19) into the weaving machine (10).

Description

Weft yam feeding arrangement With motor drive TECHNICAL FIELD The present disclosure relates to a Weft yam feeding arrangement. In particular the presentdisclosure relates to a Weft yam feeding arrangement suitable for a Weaving machineoperated at high speed and potentially also With yams With relatively high Weight per length unit.

BACKGROUNDWeft yam pre-Winders are used to eliminate yam tension Variations to ensure high textilequality and productivity of a textile machine, e.g. a shuttleless Weaving machine or knitting machine.

A general development trend in Weaving is that the speed of the Weaving machine isconstantly being increased. At the same time the Weavers strive to Weave coarser yams andalso Weaker yams. Coarser yams and higher speeds lead to increased tension of the Weftyam. Using conventional Weft yam pre-Winders, increased speeds as Well as coarser yamsresult in a bigger take off yam balloon in the Weft yam pre-Winder, Which needs to bereduced using a high braking force but thereby unfortunately leading to an undesirably high output yarn tension.

For example, When Weaving a carpet, coarse Jute is often used as Weft yam. The balloonbraking elements in a conventional Weft yam pre-Winder is typically either a brush ring or aﬂexible truncated-cone formed brake element. With the machine speeds of today a brushring is often Wom out in as little as a day and a flexible truncated-cone brake element can be Wom out in a few months.

Another example is Weaving technical fabric With coarse synthetic yams; Where one faces the same problem as in a carpet Weaving machine.

Further, When using a shuttleless Weaving machine in the form of a rapier Weaving machine,the insertion means in the rapier Weaving machine consists of one or tWo rigid or ﬂexiblerapiers that mechanically transfers the Weft yam from one end of the shed of the machine tothe other. The most common system is tWo rapiers Which meet in the middle of the shedWhere the Weft yam tip is transferred from the first, giving, rapier to the second, receiving,rapier. The first rapier is first accelerating from zero to full speed and then decelerating tozero again at the tip transfer point. This type of motion is analogous for the second rapier.This leads to a Weft yarn tension that goes from loW to high and then back to loW again. Infact, When the rapier decelerates the mass in the Weft yam causes it to move faster than therapier itself causing a surplus of yam. This effect increases With the yam count, i.e. the yamWeight per length unit, and is a real problem for coarse yams and fast machines. In order to solve this problem passive or controlled yam brakes are being used.

If the machine speed is to be increased, the mechanical arrangement for the rapiermechanism must be made as light as possible. On the other hand, higher speeds means higher yam tension Which requires a more rigid and stronger rapier system.

Weaker yams are cheaper and are thus attractive to use. Weaker yams have less tensilestrength and if a too high brake force is applied in order to control the balloon, or to giveenough tension for the rapier ﬁanction, the risk for yam break is increasing rapidly. GB1355687 describes a yam feeder Where a member directly connected to the Weavingmachine moves back and forth to remove yam in unison With the movement of the rapierfrom a yam package during both a forward and retum movement of the rapier. Hereby, the speed at Which the yam is draWn from the yam package can be reduced to one half There is a constant desire to improve Weft yam feeding to textile machines. Hence, there is a need for an improved Weft yarn feeding device.

SUMMARY It is an object of the present invention to provide an improved Weft yarn feeder arrangement.

This object and/or others are obtained by the Weft yam feeding device as set out in the appended claims.

As has been realized, it Would be advantageous to reduce the speed at Which yam is draWnfrom a yam storage such as Weft yam pre-Winder or a bobbin feeder to a Weaving machine.This Would reduce the forces required to cope With When increasing the speed of theWeaving machine, in particular When a coarser yam having a relatively high Weight per length unit is used such as Jute, some synthetic yams or carbon fiber.

Also While the device described in GB 1355687 allows for a reduced speed at Which theyam is draWn from the yam feeder, it has limitations and draWbacks. First the device of GB1355687 has a limitation in that the speed reduction can only be 50% and not more. Also,the fact that the member is directly connected to the Weaving machine and moves back andforth to remove yam in unison With the movement of the rapier from a yam package duringboth a forward and retum movement of the rapier makes it impossible to draW yam from theyam storage When the rapier is not moving such as during beat up. In other Words in GB1355687 it is only possible to draW yam from a yam storage When the rapier is moving. Asa result a significant fraction of the time available during a Weaving cycle is not used todraW yam from the yam storage. This is because during a significant fraction of the Weavingcycle the rapier(s) is/ are typically not moving. Second, the device moves in unison With therapier. This results in that the speed at Which the yam is draWn from the yam feeder isdirectly proportional to the speed of the rapier and hence varies significantly during a Weft insertion cycle of a rapier machine. The fact that the device in accordance With GB 1355687 moves in unison With the rapiers as it is mechanically coupled to the drive of the rapiers inthe Weaving machine limits the ﬁanctionality as it is not possible to improve the function byfollowing another movement in order to even out the speed even more and/or compensatefor other movements in the Weaving machine. Third, the device requires a traveler guidedalong a rail, Which imposes additional friction forces, Which could be a disadvantage in some applications.

In accordance With one embodiment a Weft yarn feeding device for feeding yam to aWeaving machine is provided. In the Weaving machine Weft yarn is inserted into the shedand the Weaving machine is provided With at least one rapier. The Weft yarn feeding devicehas at least one yam guide provided on a moving member driven by a controlled motorcomprised in the yam feeding device to cause the moving member to move back and forth.When in use, yam is draWn from a Weft yarn storage via said at least one guide provided onsaid moving member to the Weaving machine. Hereby a yam buffer of variable size can beformed. The motor can be driven to increase the yam buffer When the Weft yam insertionspeed of a rapier is low and to release yam from the yam buffer When the yam insertionspeed of a rapier is high. This Will cause the maximum yam take off speed from the Weft yam storage to be significantly reduced.

In accordance With one embodiment the motor is adapted to be controlled using a model ofa parameter related to a set of positions of the rapier(s) in the Weaving machine. Hereby themotor can be driven to adjust the yam buffer in a pattem mirroring/representing themovements in the Weaving machine. In particular the motor can be adapted to be controlledusing a model of different angular positions in the Weaving machine at particular points inthe time of the Weaving cycle. Hereby the motor can be driven to ultimately adjust the yam buffer to draw yam from the Weft yam storage at essentially constant speed.

In accordance With one embodiment the motor can be adapted to move the moving memberin a pattem to minimize the maximum speed of the yam drawn from the weft yarn storage during a weaving cycle of the weaving machine.

In accordance with one embodiment the motor is adapted to move the moving member, withits yam guide, in a pattem whereby the maximum speed of the yam drawn from the weft yam storage is less than 50% of the maximum speed of the rapier(s).

In accordance with one embodiment the motor is adapted to move the moving member in apattem to also compensate for yam movement caused by at least one of the following eventsin the weaving machine: weft selector movement, beat up, yam cutting, rapier start, weft yam tip transfer and weft yam arrival.

In accordance with one embodiment the moving member is an arm. The arm can be directlymounted on the motor. In particular the arm can be connected to the output shaft of the motor.

In accordance with one embodiment the moving member is a member following a linear path. The moving member can be driven back and forth along the linear path.

In accordance with one embodiment the weft yarn feeding device is adapted to draw theyam from a weft yarn storage comprising a pre-winder. In an altemative embodiment the weft yam feeding device is adapted to draw yam directly from a bobbin.

The invention also extends to methods for controlling a weft yam feeding device inaccordance with the above and to a controller and computer program product for controllingthe weft yarn feeding device in accordance with the above. The invention further extends toan arrangement comprising a weft yam feeding device in accordance with the above. The arrangement can in some embodiments comprise a slip feed device for the weft yam.

BRIEF DESCRIPTION OF THE DRAWINGSThe present invention Will now be described in more detail by Way of non-limiting examples and With reference to the accompanying draWings, in Which: - Fig. l is a view illustrating a Weft yam feeding arrangement, - Figs. 2 and 3 are views illustrating alternative Weft yarn feeding arrangementconfigurations, - Fig. 4 is a diagram illustrating different speed parameters as a function of Weaving cycleangle in a Weaving machine, - Figs. 5a and 5b illustrate some steps When controlling a Weft yarn feeding device, - Fig. 6 is a schematic view of a controller, - Fig. 7 illustrate the principles of a slip feed device for the Weft yam, - Figs. 8 - 10 shoW different exemplary embodiments of a Weft yarn feeding device With aslip feed device, - Fig. ll illustrates an altemative slip feed device, and - Fig. 12 illustrates an altemative set up of a Weft yam feeding arrangement.

DETAILED DESCRIPTION In the following a Weft yam feeding arrangement for a Weaving machine Will be described.In the figures, same reference numerals designate identical or corresponding elementsthroughout the several figures. It Will be appreciated that these figures are for illustrationonly and are not in any Way restricting the scope of the invention. Also it is possible tocombine features from different described embodiments to meet specific implementation needs.

In order to reduce the speed at Which yam is draWn from a Weft yarn pre-Winder or directlyfrom a bobbin, a yarn feeding device is provided comprising a controlled motor. The motor is a motor designated for the device and can be controlled independently of the movements of a weaving machine. The yarn feeding device comprises a yam path deviating/yamdeﬂecting arm With a yam guide, or a similar member, driven by the motor. The yarnfeeding device forms an interrnediate yam buffer between the weft yarn storage and theweaving machine. In accordance with some embodiments the yam feeding device is adaptedto draw yam directly from a bobbin. In accordance with an advantageous embodiment a pre-winder is provided after the bobbin and the device is adapted to draw yam from the pre-winder. By using a pre-winder before the yarn feeding device, the weft yam tension in to theyam feeding device is lower and typically much more even than if the yam feeding devicewould take yam directly from the bobbin. The weft yam tension in to the device istransferred, and potentially even amplif1ed, via the yam feeding device to the weavingmachine. Hence, a pre-winder before the yarn feeding device ensures a lower and muchmore even yam tension to the weaving machine which results in less stops and a betterweaving process. The aim is to reduce and to even out the yam take off speed, either fromthe bobbin or if a pre-winder is provided, from the pre-winder. By this step two things are achieved: The maximum yam take off speed from the weft yam storage is lower. This will forexample reduce the wear of balloon braking elements if a pre-winder is used. As the speedis lower also the balloon will be smaller and the balloon braking elements can be set to a lower yam tension, thereby reducing the wear even further.

Also, the reduced yarn take off speed will give a lower yam tension which in tum gives alower stress on the yam and also a lower stress on the rapier insertion mechanism. Inaccordance with one embodiment the target is set to have approximately constant yarn takeoff speed from the yam storage such as a pre-winder or directly from a bobbin. This meansthat the yam that the rapier takes is coming both from the interrnediate yam buffer formedby the device and also at the same time from the weft yarn storage. The maximum yamspeed from the weft yarn storage can then typically be reduced with more than 50% or up to 70% or even more of the maximum speed of the rapier.

Fig. 1 shows an exemplary embodiment of a weft yam feeding device 16 forrning a motordriven yam buffer device between a weft yarn storage and a weaving machine 10. In Fig. 1,the weaving machine 10 is a double sided rapier weaving machine having two rapiers 11and 12. In the embodiment of Fig. 1 the weft yarn storage comprises a pre-winder 14. The pre-winder 14 can in tum draw yam 40 from a bobbin 13.

The weft yam feeding device 16 comprises a motor 18. The motor is a motor 18 designatedfor the yam feeding device 16 and separate from any motor of the weaving machine 10.The motor 18 drives a moving member 19. In Fig. 1 the moving member 19 is an armdirectly connected to the motor 18. The moving member can be directly connected to theoutput shaft 15 of the motor 18. However, it is also envisaged that the arm is not directlyconnected to the motor 18. The moving member can also be another type of element drivenby the motor 18. The motor 18 is adapted to drive the moving member to a desired positionbased on an input signal. It is preferred that that the motor is a high performance electricalmotor. The electrical motor should be fast enough to enable rapid movements required bythe moving member 19. In another exemplary embodiment (not shown) the moving memberis driven back and forth along a linear path by the motor or a path with some pre-deterrnineddeviation from a linear path. The moving member 19 is provided with at least one guide 20adapted to guide yam 40 along a path formed by the position of the moving member 19. Theguide 20 can be any suitable element which is able to form a yam loop. For example the guide 20 can be an element on which the yam 40 can slide or roll.

The motor 18 can be driven in any suitable way to provide any desired movement of themoving member. In particular a controller (see below) can be used to drive the separatemotor 18 of the yam feeding device to perform a movement pattem that does not exactlyfollow a pattem related to the actual motion of the rapier(s). In other words the drive of the motor 18 is autonomous relative to the drive of the rapiers of the weaving machine.

In Fig. 1 an arrangement where guide elements 22, 24 are provided before and after the weftyam feeding device 16 is shown. When the moving member 19 of the weft yam feedingdevice moves, the yam 40 running from the guide element 22 via the guide 20 on themoving member 19 and via the guide member 24, a yam buffer of varying length will be formed.

The configuration shown in Fig. l will add about 360° extra friction angles for the yam 40.This will increase the yam tension and potentially reduce the positive effect from the weftyam feeding device 16. By providing the guide elements 22 and 24 spaced more apart, theadded friction angles can be reduced. Fig. 2, which is similar to the arrangement of Fig. 1,shows an embodiment with the guide elements 22 and 24 spaced more apart. The guideelements can in accordance with some embodiments be spaced apart with at least 25 cm or50 cm. In accordance with some embodiments the guide elements 22, 24 can be spacedapart with at least 100 cm. A consequence of a set-up as shown in Fig. 2 is that the friction angles of the guide elements 22, 24 will vary with the position of the guide 20.

In accordance with some other embodiments one or both the guide elements are omitted.This will limit the friction angles and keep them constant. In Fig. 3 an embodiment with noguide elements 22, 24 is shown. In the configuration of Fig. 3 the added friction angle isalways around 180°, such as between 150° and 210°. Hence the only yam guide element ofthe moving member that the yam passes from the yam storage to the weaving machine isthe guide 20. This is made possible by locating the yam storage closer to the weavingmachine than the weft yam feeding device and arranging the yarn guide 20 move betweentwo end positions, where the two end positions, the yam output from the yam storage, andthe yam input to the weaving machine are located essentially along one line. It also enables a layout that is more compact in a direction perpendicular to the insertion direction.

Control of the moving member is primarily based on the rapier movement, with the target to have: _10- ° a weft yam take off speed from the weft yam storage that is within a small targetrange and preferably constant,° a low yam tension in to the weaving machine, ° a low torque need for the motor These factors can be balanced in different ways to achieve a desired yam take off speed atdifferent angular weaving cycle positions of the weaving machine. In Fig. 4 an exemplaryset-up for a double sided rapier weaving machine is illustrated where the yam speed atinsertion is shown by the line 50. This speed is the result of the rapiers at different angularweaving cycle positions in the weaving machine. The movement of the moving member(and the yarn guide used to form a yam loop) driven by the controlled motor is depicted bythe line 60. As can be seen in Fig. 4, the motor can be driven to release yam from the yambuffer formed by the yam loop when the rapier is picking yam at a high speed, in particularhigher than the average yam pick speed, and to fill the yam buffer when the rapier ispicking yam at a low speed, in particular lower than the average yam pick speed, and alsoduring the part of the weaving machine cycle when none of the rapiers are engaged inpicking yam. During most of the weaving machine cycle, yam is taken from the weft yamstorage with relatively small variations in the take-of-speed. Such a control method canresult in that the yam take-off speed from the weft yam storage will be essentially the sameduring the entire weaving cycle of the weaving machine as is depicted by line 70. As a result the maximum yam take-off speed can be signif1cantly reduced.

The diagram of Fig. 4 is for illustration purpose only. The machine angles are approximateand serve(s) only as examples. The timing of the different actions in the weaving machine differs for different machine types.

Here during machine angle 0 to 70 degrees, the reed is moving backwards and the shed is opening. The rapiers are not engaged in picking any yam. In this time interval, the _11- controlled motor 18 is programmed to drive the moving member 19 in a movement in order to increase the yam buffer by pulling yam from the yam storage.

At 70 degrees the giving rapier takes the yam and the insertion starts.

At 70-90 degrees the controlled motor 18 is programmed to drive the moving member 19 ina movement to increase the yam buffer. The speed at Which the moving member is driven isdecreased, preferably gradually, as the rapier speed increases. In this phase both the movingmember and the Weaving machine takes yam from the yam storage. The combined speed ofthe rapier and the moving member result in a Weft yam take off speed from the yam storage speed close to the average yam speed.

At 90 degrees the moving member changes direction of its movement and now the movingmember is driven to release yam, by controlling the motor to drive the moving member inthe other direction. The result of the moving member release speed and the rapier speed still gives a yam storage speed in the same magnitude as the average yam speed.

At 90 to 130 degrees the yam feeding device releases yam from the buffer. The Weaving machine takes yam both from the buffer and from the yam storage.

At 130 degrees the rapier has reached its top speed. The moving member is at maximum negative speed and this is the point When most yam is released from the buffer.

At 130 to 180 degrees the rapier decelerates and at 180 degrees the rapier speed is zero.

At 130 to 165 the yam feeding device still releases yam from the buffer.

At 165 degrees the moving member is driven to change direction and the yam buffer is increased. _12- At 165 to 195 degrees the yam buffer increases. When the rapier speed is close to zero the yarn tension drops as a result of the retardation of the rapier and the mass forces of the yam.

The moving member is controlled to be driven to build up the buffer to both counteract thetension drop and to increase the yam in the buffer to have enough yam for the receivingrapier cycle. In this period the Weaving machine takes yam from the yam storage. As themoving member is moved to build up the yam buffer and the rapier still moves, both therapier and the moving member takes yam from the yam storage, thus increasing the yam tension at the yam tip, Which is desired in order to ensure a safe yam tip transfer function.

At 180 degrees the transfer takes place. The giving rapier transfers the yam tip to the receiving rapier.

Between 180 and 300 degrees the receiving rapier cycle takes place, and the movements ofthe rapier and moving member of the yam feeding device is repeated in a similar or analogous Way as for the giving rapier described above.

At 300 degrees the receiving rapier releases the yam and the Weft insertion is ready.

At 270 degrees the moving member is driven to increase the buffer, to increase the yam tension before the end of insertion and to build up the buffer for next insertion.

Between 300 and 360 degrees the beat up, When the reed is pushing in the inserted Weftthread into the Woven fabric, takes place. During this period the moving member is moved to increase the buffer to be ready for the next pick of the Weaving machine.

The aim during all or at least most of the above described different angular intervals of aWeaving machine cycle is to achieve an even Weft yam take off speed from the yam storage that is the same as the average Weft yam take off speed (With some pre-deterrnined _13- tolerance) or a Weft yam take off speed below a pre-deterrnined maximum Weft yam takeoff speed. The motor is therefore controlled to be driven to adjust the buffer formed by the moving member to even out the take-off speed from the yam storage.

To reach the target of a mainly constant yam speed from the Weft yarn supply a relativelybig motor and a long yarn loop forrning moving member is typically needed. In some casesthere is not space enough for arrangements requiring much space, or for other reasons asystem having a smaller size is desired. If for example a Weaving machine has 8 Weft yamchannels, 8 separate Weft yarn feeding devices are needed, one for each channel. MultipleWeft yam feeding devices require a lot of space that might not be available. A smallersystem can then be a good altemative. A system With a smaller motor and/or a smaller yarnloop forming moving member cannot result in a mainly constant yam speed from the Weftyam supply. HoWever, such a system Will still reduce the highest yam speeds and result inlower yam tension. Thus such a system Will still be advantageous and an improvement compared to existing Weft yarn feeding systems.

In the above description a single or double sided rapier Weaving machine having one or tworapiers has been assumed. Further, there exists other types of Weaving machines With morethan one shed, for example a carpet or velvet machine has typically tWo sheds, With tWo ormore sets of rapiers that move in parallel from the same side. The here described Weft yarnfeeding device can then be implemented in such a Way that one yarn loop forrning movingmember is designed to feed/ supply yam to more than one rapier in the same time. Forexample, the moving member 19 can have tWo yam guides 20 that are connected upstreamWith tWo Weft yarn storages and doWnstream With tWo rapiers Working in parallel to tWodifferent sheds in the same Weaving machine. Generally the Weft yarn feeding device as described herein can be used in any type of rapier Weaving machine.

In Fig. 5a, a ﬂoW chart illustrating some steps that can be performed When controlling a motor used to drive a Weft yam feeding arrangement as described herein. The Weft yarn _14- feeding arrangement will form a yam buffer having Variable length. First, in a step 501, amodel of the movements of the weaving machine at different angular weaving cyclepositions of the weaving machine is deterrnined. The movement model can typically reﬂectthe weft yam movement or weft yarn tension variations at different angular weaving cyclepositions of the weaving machine. Next, in a step 503 a position signal indicative of thecurrent angular weaving cycle position of the weaving machine is received. Then, in anoptional step 505, a model of different events in the weaving machine are deterrnined. Theevents can for example be one or more of weft selector movement, beat up, yam cutting,rapier start, yarn tip transfer and yam arrival. Then, in a step 507, the movement of themotor 18 and thereby the yarn buffer formed by the yam feeding device comprising themotor and associated parts are controlled based on the model of the weaving machine atdifferent angular weaving cycle positions. The control can in accordance with someembodiments also take into account different events in the weaving machine during eachweaving cycle as will be described in more detail below. The model can also take intoaccount the geometry of the yam feeding device such that the model can translate a drivesignal to the motor to a corresponding adjustment of the weft yam buffer. In other words bymodelling how a particular drive signal will change the yarn buffer, the motor drive signalcan be controlled to adapt the yam buffer size to match the movements in the weavingmachine to meet the ultimate aim of reducing the maximum weft yam take off speed from the yam storage.

In Fig. 5b a control model illustrating the above is depicted. First in a model step 521, adifference between the weft yam movement caused by the insertion into the weavingmachine and the desired set weft yam take off speed is deterrnined. The difference valuedeterrnined in step 521 is translated to a desired buffer adjustment illustrated in model step523. Knowing how the buffer is to be adjusted, a motor drive signal is output based on thegeometry of the weft yam buffer (or a model thereof) and the desired buffer adjustment. Asa result the motor will be driven to cause the buffer to be adjusted over time to keep the set weft yam take off speed from the yam storage at the set speed. _15- In Fig. 6 a controller 26 for controlling a weft yarn feeding device is depicted. Thecontroller 26 can comprise an input/output 8l for receiving input signals indicative of theangular weaving cycle position of the weaving machine and for outputting a motor controlsignal to the motor l8. The controller 26 further comprises a micro-processor that also canbe referred to a processing unit 82. The processing unit 82 is connected to and can executecomputer program instructions stored in a memory 83. The memory 83 can also store datathat can be accessed by the processing unit 82. The data in the memory can in particularcomprise a model of the movements of the weaving machine l0. The computer programinstructions can be adapted to cause the controller to control the motor in accordance withthe teachings herein. The controller can be located at any suitable location. For example thecontroller can be integrated in the motor l8. The controller can input output data using any suitable means. Both wireless and wireline communication devices can be used.

To limit the load on the motor, a light weight moving arm or other yam loop forrningmember can be used. It can be of several types, for example using light and stiff materials like carbon fiber, or a light weight design in aluminum sheet.

A moving member working partly counter to the rapier movement as described hereinabovewill give further advantages. As earlier described, in a double sided rapier weavingmachine, the rapier and thus the weft yam is slowing down strongly twice in each insertioncycle. To keep the yam stretched, a controlled brake is often used. For coarse weft yarns thebrake force must be very high, which has negative effects on both the weft yam and the weftinsertion ﬁanction, as well as the fact that a very large and energy consuming controlledbrake is needed. During the retardation of the rapier, the weft yam feeding device asdescribed herein will drive the moving member 19 in order to increase the yam buffer. Thisaction will also stretch the weft yam towards the rapier and takes up weft yarn from the weftyam storage. This action will act to reduce the need for a controlled tensioner, or even in some applications eliminate it. Hence the weft yam feeding device can be controlled to _16- increase the weft yam buffer at events when the yam is to be stretched. This can for example be when a rapier is retarding.

Another event is at beat up and cutting of the weft yam, Where often a surplus of weft yarnbetween the pre-winder and weaving machine is created due to the geometry and movementof the shed/slay and other parts involved in the weft insertion. Today a spring loaded take updevice is often used, but has some disadvantages. One disadvantage is that the spring loadedsystem is sometimes to slow to follow the yam slack that is created. Another disadvantage isthat the yam force is used to overcome the spring force and move the take up device, thuscreating additional yam tension. That problem can be avoided with a weft yarn feedingdevice as described herein. The here described weft yam feeding device can be controlled tocompensate for the drop in yam tension by moving the member 19 to stretch the yam.Similarly, before a yarn tension peak is reached the member 19 can be moved to decrease the yam tension.

In another exemplary embodiment a slip feed device is added. The slip feed device is adriven roller that rotates with a peripheral speed that is higher than the necessary yam speed.Such a device is described in US 5660213. When the weaving machine rapier pulls the weftyam during the insertion, the yam will be pulled against the roller and the friction betweenthe yam and the rotating roller will contribute to pull the yam further thus decreasing theyam tension. As soon as the roller gives more speed to the yam than what is consumed bythe weaving machine the force from the yam against the roller will decrease and hence thepulling force will also decrease until a balance is reached and the roller will not give anyfurther force to the yam. Fig. 7 depicts an exemplary slip feed device 28 in two different views.

Using a slip feed device in the weft yarn feeding device as described herein can lower the yam tension in to the weaving machine. _17- By combining a weft yarn feeding device with a motor driven yarn buffer as describedherein with a slip feed device, the disadvantage of the added friction angles can be reduced,and even turned into a yet better system. Several layouts are possible. The system can beoptimized for low yam tension, or the combination can be used to build a compact system that fits to the available space at the weaving machine.

In Fig. 8 a weft yam feeding device comprising a motor driven yarn buffer combined with a slip feed roller after the yam buffer is shown.

If the slip feed device is instead placed before the yam buffer, the yam tension of the yamfed to the buffer will be lower. The load on the yam buffer will be lower enabling a lowerstrength and thus weight of the moving arm (when an arm is used) in the weft yarn feedingdevice. Both the lower yam tension on the moving arm and the lower weight will reduce the load on the motor that drives the arm. Such a configuration is shown in Fig 9.

A slip feed device can also be provided both before and after the yam buffer. In accordance with one embodiment the same slip feed device is used both before and after the yam buffer.

A configuration using the same slip feed device both before and after the yam buffer is shown in Fig. l0.

The slip feed device 28 can be designed in many different ways. One design is shown inFig. ll. The design in Fig. ll comprises two rolls 29, 30. The rolls are arranged followingeach other along the path of the yam. The rolls 29, 30 can be controlled to move in relation to each other.

As is realized numerous variations and alterations can be made to achieve the reduced yamtake-off speed and other advantages obtained by the methods and devices as describedherein. For example, the motor driven moving element can have different configurations.

The number of guides on the moving element can be more than one. One altemative _18- conﬁguration is shown in Fig. 12. In Fig 12 a Weft yam feeding device 16 has an arrnprovided With two yarn guides 20. The guides 20 can then be formed by a pair of elementseach. In the shown embodiment one guide is located at each end of an arrn forming themoving element. The arrn can be driven to rotate back and forth to adjust the yam buffer ofthe yam feeding device. Further, the motor used can be any suitable motor that can be controlled to drive a moving member in accordance With the above.

Claims

1. A Weﬁ yarn feeding device (16) for feeding Weft yam (40) to a Weaving machine (10),Wherein the yarn is inserted into the shed of the Weaving machine having at least one rapier(11, 12), the Weft yarn feeding device comprising at least one yam guide (20) provided on amoving member (19) driven by a controlled motor (18) comprised in the Weft yarn feedingdevice to cause the moving member to move back and forth and Wherein, When in use, yamis draWn from a Weft yarn storage (13, 14) via said at least one guide (20) provided on said moving member (19) to the Weaving machine (10).

2. The yam feeding device (16) according to claim 1, Wherein the controlled motor (18) isadapted to be controlled using a model of a parameter or a set of parameters related to a setof positions of the rapier(s) in the Weaving machine (10) at different angular Weaving cyclepositions in the Weaving machine at corresponding particular points in the time of the Weaving cycle.

3. The yam feeding device (16) according to claim 1 or 2, Wherein the yam storage (13, 14)is located closer to the Weaving machine (10) than the Weft yam feeding device and Whereinthe yam guide (20) is arranged to move between two end positions, Where the two endpositions, a yam output from the yam storage, and a yam input to the Weaving machine are located essentially along one line.

4. The yam feeding device (16) according to any of claims 1 - 3, Wherein the controlledmotor (18) is adapted to move the moving member (19) in a pattem to minimize themaximum speed of the yarn draWn from the Weft yam storage (13, 14) during a Weaving cycle of the Weaving machine.

5. The yam feeding device (16) according to any of claims 1 - 4, Wherein the controlled motor (18) is adapted to move the moving member (19) in a pattem Whereby the maximum _20- speed of the yam draWn from the Weft yam storage (13, 14) is less than 50% of the maximum speed of the rapier(s).

6. The yam feeding device (16) according to any of claim 1 - 5, Wherein the controlledmotor (18) is adapted to move the moving member (19) in a pattem to also compensate foryam movement caused by at least one of the following events in the Weaving machine: Weftselector movement, beat up, yarn cutting, rapier start, Weft yam tip transfer and Weft yam arrival.

7. The yam feeding device (16) according to any of claim 1 - 6, Wherein the moving member (19) is an arm.

8. The yam feeding device (16) according to claim 7, Wherein the arm is directly mounted on the output shaft of the motor (18).

9. The yam feeding device (16) according to any of claim 1 - 6, Wherein the moving member (19) is a member folloWing a linear path.

10. The yam feeding device (16) according to any of claims 1 - 9, Wherein the Weft yarnfeeding device is adapted to draW the yam from a Weft yam storage comprising a yam pre- Winder (14).

11. The yam feeding device (16) according to any of claims 1 - 9, Wherein the Weft yarnstorage is a bobbin (13) and the Weft yarn feeding device is adapted to draw yam (40)directly from the bobbin.

12. A Weft yarn feeding arrangement comprising a Weft yam storage (13, 14), a Weft yarn feeding device (16) according to any of claims 1 - 11, a Weaving machine (10) and a slip _21- feed device (28) interconnected between the weft yam feeding device and the weaving machine.

13. The yam feeding arrangement according to claim 12, wherein a slip feed device (28) is interconnected between the weft yarn(s) storage (13, 14) and the weft yarn feeding device (16).

14. The yam feeding arrangement according to claim 12, wherein a slip feed device (28) is interconnected between the weft yarn feeding device (16) and the weaving machine (10).

15. The yam feeding arrangement according to claim 12, wherein a slip feed device (28) isinterconnected both between the weft yarn(s) storage (13, 14) and the weft yarn feeding device (16) and between the weft yam feeding device and the weaving machine (10).

16. A method of controlling a weft yarn feeding device (16) feeding yam (40) to a weavingmachine (10), wherein yam is inserted into the shed of the weaving machine having at leastone rapier (1 1, 12), the weft yarn feeding device comprising at least one yam guide (20)provided on a moving member (19) driven by a controlled motor (18) of the weft yarnfeeding device to cause the moving member to move back and forth and wherein, when inuse, yam is drawn from a weft yarn storage (l3, 14) via said at least one guide (20) providedon said moving member (19) to the weaving machine (10), the method comprising using amodel of the movements of the weaving machine at different angular weaving cyclepositions of the weaving to control the motor using a signal representative of the current position of the weaving machine.

17. A computer program product comprising computer program code adapted to, whenexecuted on a computer causes the computer to control a motor (18) in accordance with claim 16.