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Title:
YARN FEEDING DEVICE WITH LONG YARN BUFFER
Document Type and Number:
WIPO Patent Application WO/2018/030932
Kind Code:
A1
Abstract:
Described are, among other things,methods and devices for feeding yarn to a textile machine(10). The yarn feeding device comprises a moveable yarn carrier (24) adapted to transport yarn in a first, forward direction and a loop former (18) adapted to draw yarn from a yarn storage (14). The device also has moveable loop keeping members (20) arranged at opposite lateral sides of an input section of the moveable yarn carrier, wherein the loop former is adapted to position yarn on the moving loop keeping members by moving the yarn from side to side. The moveable loop keeping members are adapted to hold the yarn positioned thereon and to release the yarn onto the moveable yarn carrier in a meandering pattern at an input area of the moveable yarn carrier and the yarn lying on the moveable carrier is adapted to leave the moveable yarn carrier at an output section of the moveable yarn carrier.

Inventors:
JOSEFSSON, Pär (Polonäsgränd 67, Borås, 507 65, SE)
JOHANSSON, Birger (Kandidatvägen 6, Ulricehamn, 523 33, SE)
SHAFIEI, William (S:t Michelsgatan 4C, lgnr 1001, Borås, 504 32, SE)
Application Number:
SE2017/050670
Publication Date:
February 15, 2018
Filing Date:
June 20, 2017
Export Citation:
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Assignee:
IRO AKTIEBOLAG (Box 54, ULRICEHAMN, 523 22, SE)
International Classes:
D03D47/34; B65H51/22
Domestic Patent References:
WO2000048474A12000-08-24
Foreign References:
DE3344835A11985-06-13
EP0498773A11992-08-12
DE2550118A11977-05-18
US3825198A1974-07-23
GB1355687A1974-06-05
Attorney, Agent or Firm:
SANDSTRÖM & SANDSTRÖM IP AB (Boda, Sigtuna, 193 91, SE)
Download PDF:
Claims:
CLAIMS

1. A yarn feeding device (16) for feeding yarn (40) to a textile machine (10), the yarn feeding device comprising:

- a moveable yarn carrier (24) adapted to transport yarn in a first, forward direction,

- a loop former (18) adapted to draw yarn from a yarn storage (14),

- moveable loop keeping members (20) arranged at opposite lateral sides of an input section of the moveable yarn carrier, wherein the loop former is adapted to position yarn on the moving loop keeping members by moving the yarn from side to side, wherein the moveable loop keeping members are adapted to hold yarn positioned thereon and to release yarn onto the moveable yarn carrier in a meandering pattern at an input area of the moveable yarn carrier and; wherein the moveable yarn carrier comprises an output section, from which output section yarn lying on the moveable carrier is adapted to leave the moveable yarn carrier. 2. The yarn feeding device according to claim 1, wherein the loop former is adapted to position yarn on the moveable loop keeping members using a movement being

predominantly perpendicular to the first direction.

3. The yarn feeding device according to claim 1 or 2, wherein the moveable loop keeping members are pins (20).

4. The yarn feeding device according to claim 3, wherein the pins are semi-cylindrical.

5. The yarn feeding device according to any of claims 1 - 4, further comprising a spring biased element (65) provided to press yarn against the moveable loop keeping member from the outside of the moveable loop keeping member. 6. The yarn feeding device according to any of claims 1 - 5, wherein the moveable loop keeping members are located laterally outside the movable yarn carrier.

7. The yarn feeding device according to any of claims 1 - 5, wherein the moveable loop keeping members are located projecting through the moveable yarn carrier.

8. The yarn feeding device according to any of claims 1 - 7, wherein at least one sensor (17) is provided to detect yarn on the moveable yarn carrier.

9. The yarn feeding device according to any of claims 1 - 8, further comprising a controller (19) adapted to control the drive of the yarn feeding device in response to one or more predetermined parameters.

10. The yarn feeding device according to claim 9, wherein the pre-determined parameters comprise sensor signals.

11. The yarn feeding device according to claim 9 or 10 wherein the pre-determined parameters comprise input from the textile machine.

12. The yarn feeding device according to any of claims 1 - 11, further comprising at least one endless belt (26) distanced from the moveable carrier and moving in parallel with the moveable yarn carrier.

13. The yarn feeding device according to claim 12, wherein said at least one distanced endless belt comprises a first yarn movement restriction means (29).

14. The yarn feeding device according to any of claims 1 - 13, wherein the moveable yarn carrier is an endless belt. 15. The yarn feeding device according to any of claims 1 - 14, further comprising an outlet yarn guide (34) at an end section of the moveable yarn carrier, the yarn guide being located at a flat section of the moveable yarn carrier.

16. The yarn feeding device according to any of claims 1 - 15, further comprising a second movement restriction means (32) located at an end section of the moveable yarn carrier, which second yarn movement restriction means (32) is adapted to prevent yarn from leaving the moveable yarn carrier in an uncontrolled way.

17. A yarn feeding arrangement comprising a yarn feeding device according to any of claims 1 - 16, the arrangement further comprising a slip feed device (38) located before the yarn feeding device.

18. A method of controlling a yarn feeding device (16) feeding yarn (40) to a textile machine (10), wherein yarn is inserted into the textile machine, the method comprising: - drawing (501) yarn from a yarn storage (14), using a loop former (18),

- placing (503) the yarn in a meandering pattern on a movable yarn carrier by positioning the yarn on to moving loop keeping members provided at both sides of a front section of the movable yarn carrier, wherein the loop former positions the yarn on the moving loop keeping members by moving the yarn from side to side.,

- (505) transporting yarn in the first, forward, direction using the movable yarn carrier (24),

- letting (507) the yarn lying on the moveable yarn carrier leave the movable yarn carrier at an output section of the moveable yarn carrier.

19. A computer program product comprising computer program code adapted to, when executed on a computer causes the computer to control a yarn feeding device in accordance with claim 18.

Description:
Yarn feeding device with long yarn buffer

TECHNICAL FIELD

The present disclosure relates to a yarn feeding arrangement. In particular the present disclosure relates to a yarn feeding arrangement suitable for a textile machine operated at high speed and potentially also with yarns with relative high weight per length unit.

BACKGROUND

Yarn pre-winders are used to eliminate yarn tension variations to ensure high textile quality and productivity of a textile machine, e.g. a shuttleless weaving machine or a knitting machine.

A general development trend in weaving is that the speed of the weaving machine is constantly being increased. At the same time the weavers strive to weave coarser yarns and also weaker yarns. A similar trend also exists for other textile machines. Coarser yarns and higher speeds lead to increased tension of the yarn. Using conventional yarn pre-winders, increased speeds as well as coarser yarns result in a bigger take off yarn balloon in the yarn pre-winder, which needs to be reduced 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 yarn. The balloon braking element in a conventional yarn pre-winder is typically either a brush ring or a flexible truncated-cone formed brake element. With the machine speeds of today a brush ring is often worn out in as little as a day and a flexible truncated-cone brake element can be worn out in a few months. Another example is weaving technical fabric with coarse synthetic yarns; 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 flexible rapiers that mechanically transfers the yarn from one end of the shed of the machine to the other. The most common system is two rapiers which meet in the middle of the shed where the yarn 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 to zero again at the tip transfer point. This type of motion is analogous for the second rapier. This leads to a yarn tension that goes from low to high and then back to low again. In fact, when the rapier decelerates the mass in the yarn causes it to move faster than the rapier itself causing a surplus of yarn. This effect increases with the yarn count, i.e. the yarn weight per length unit, and is a real problem for coarse yarns and fast machines. In order to solve this problem passive or controlled yarn brakes are being used.

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

Weaker yarns are cheaper and are thus attractive to use. Weaker yarns have less tensile strength and if a too high brake force is applied in order to control the balloon, or to give enough tension for the rapier function, the risk for yarn break is increasing rapidly. GB 1355687 describes a yarn feeder where a member directly connected to the weaving machine moves back and forth to remove yarn in unison with the movement of the rapier from a yarn package during both a forward and return movement of the rapier. Hereby, the speed at which the yarn is drawn from the yarn package can be reduced to one half. The arrangement in GB 1355687 will form a yarn buffer. In general, a yarn buffer is an arrangement that can hold a bit of yarn that can be drawn with a small force during at least a part of the weaving cycle compared to the force required if the yarn would have been drawn directly from the yarn storage.

In US 3825198 a yarn storage is described. The yarn storage is formed by a container and has an endless belt for advancing the yarn in the container. The yarn storage is used to rid strip shaped materials from electrostatically charged materials.

There is a constant desire to improve yarn feeding to textile machines. Hence, there is a need for an improved yarn feeding device.

SUMMARY

It is an object of the present invention to provide an improved yarn feeding device and yarn feeding arrangement.

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

As has been realized, it would be advantageous to reduce the speed at which yarn is drawn from a yarn storage, such as a bobbin or a pre-winder to a textile machine. This would reduce the various forces required to cope with when increasing the speed of the textile machine, in particular when a coarser yarn having a relatively high weight per length unit is used such as Jute, some synthetic yarns or carbon fiber. Another desire is to provide yarn feeding that reduces the yarn tension.

Also, while the device described in GB 1355687 allows for a reduced speed at which the yarn is drawn from the yarn feeder, it has limitations and drawbacks. First the device of GB 1355687 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 and forth to remove yarn in unison with the movement of the rapier from a yarn package during both a forward and return movement of the rapier makes it impossible to draw yarn from the yarn storage when the rapier is not moving such as during beat up. In other words, in GB 1355687 it is only possible to draw yarn from a yarn storage when the rapier is moving. As a result, a significant fraction of the time available during a weaving cycle is not used to draw yarn from the yarn storage. This is because during a significant fraction of the weaving cycle the rapier(s) is/are typically not moving. Second, the device moves in unison with the rapier. This results in that the speed at which the yarn is drawn from the yarn feeder is directly proportional to the speed of the rapier and hence varies significantly during a cycle of a rapier machine. The fact that the device moves in unison with the rapiers as it is mechanically coupled to the rapiers in the weaving machine limits the functionality as it is not possible to improve the function by following other movements in the weaving machine in order to even out the speed even more and/or compensate for other movements in the weaving machine. Third, the device requires a traveler guided along a rail, which imposes additional friction forces and a moving part, which could be a disadvantage in some applications.

In a traditional pre-winder, the yarn is drawn from a cylindrical drum. At high speeds the yarn will form a take-off balloon, which increases the yarn tension significantly. With a coarse yarn this ballooning effect will be accentuated and the yarn tension thereby raises even more. It is therefore desired to provide a yarn feeding device that will not be limited or at least less limited with regard to high speeds for, in particular, coarse yarns. This would then enable a higher productivity of a textile machine fed from the yarn feeding device. The here described yarn feeding device does not store the yarn on a cylindrical drum but instead stores the yarn lying freely in a meandering pattern. Since the yarn is not drawn from a drum but instead from yarn lying flat, the yarn take-off balloon from traditional pre-winders will not be formed. The result is a much lower yarn take-off tension and that the speed of the textile machine can be increased to ultimately increase the productivity of the textile machine. In accordance with one embodiment a yarn feeding device for feeding yarn to a textile machine is provided. The yarn feeding device comprises a moveable yarn carrier adapted to transport yarn in a first, forward direction and a loop former adapted to draw yarn from a yarn storage. The yarn feeding device further comprises moveable loop keeping members arranged at both sides of an input section of the moveable yarn carrier, wherein the loop former is adapted to position yarn on the moving loop keeping members by moving the yarn from side to side. The movement can comprise a movement being predominantly perpendicular to the first direction. The moveable loop keeping members are adapted to hold the yarn positioned thereon and to release the yarn onto the moveable yarn carrier in a meandering pattern at an input area of the moveable yarn carrier and the yarn lying on the moveable yarn carrier is adapted to leave the moveable yarn carrier at an output section of the moveable yarn carrier. Hereby a yarn buffer is formed that can draw yarn from a yarn storage at a low speed and which can keep a large yarn buffer that can supply yarn to a textile machine with low or in some instances practically no yarn tension compared to taking yarn directly from the yarn storage.

In accordance with one embodiment the moveable loop keeping members are pins. The pins can be cylindrical or in one embodiment semi-cylindrical. Hereby a yarn can easily be placed on and leave the moveable loop keeping members.

In accordance with one embodiment the moveable loop keeping members are located laterally outside the moving carrier. In an alternative embodiment, the moveable loop keeping members are located projecting through the moveable yarn carrier. In accordance with one embodiment at least one sensor is provided to detect the yarn on the moveable yarn carrier. For example, the position of the yarn can be determined. Hereby input to a control mechanism can be provided. In accordance with one embodiment a controller adapted to control the drive of the yarn feeding device in response to one or more pre-determined parameters. The pre-determined parameters include one or many of sensor signals and input from the weaving machine. In accordance with one embodiment at least one endless belt distanced from the moveable yarn carrier and moving in parallel with the moveable carrier is provided. Hereby an improved control of the yarn lying on the moveable carrier can be obtained. Further, a first yarn movement restriction means can be provided on such a belt moving in parallel with the moveable carrier.

In accordance with one embodiment the moveable yarn carrier is an endless belt. Hereby an efficient carrier can be obtained that is easy to control.

In accordance with one embodiment an outlet yarn guide is provided at an end section of the moveable yarn carrier, the yarn guide being located at a flat section of the moveable yarn carrier. Hereby improved control of yarn about to leave the moveable yarn carrier is achieved. In accordance with one embodiment a second yarn movement restriction means are provided and adapted to prevent yarn from leaving the moveable yarn carrier in an uncontrolled way. The movement restriction means can advantageously be located at an end section of the moveable carrier.

In accordance with one embodiment, a spring biased element can be provided to press yarn against the loop keeping member from the outside of the loop keeping member. Hereby the yarn can be kept in place while being moved by the loop keeping members.

In accordance with one embodiment a slip feed device can be located before the yarn feeding device. The invention also extends to methods for controlling a yarn feeding arrangement in accordance with the above and to a controller and computer program product for controlling the yarn feeding device in accordance with the above.

BRIEF DESCRIPTION OF THE DRAWINGS

The 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. 1 is a view illustrating a yarn feeding arrangement,

- Fig. 2 is a view in perspective of a yarn feeding device,

- Fig. 3 is a view of a yarn feeding device comprising a pair of upper belts,

- Figs. 4a and 4b are different views illustrating placing yarn in a meandering pattern onto a moveable yarn carrier of a yarn feeding device,

- Fig. 5 is a view illustrating a moveable yarn carrier in accordance with one embodiment with pins projecting through the moveable yarn carrier,

- Fig. 6a and 6b are different views showing the end section of a moveable yarn carrier,

- Fig. 7 shows the general principles of a slip feed device.

- Fig. 8 shows a yarn feeding arrangement with a slip feed device,

- Fig. 9 is a flow chart illustrating different steps performed when forming a yarn buffer,

- Fig. 10 is a view of a controller, and

- Figs. 11a and 1 lb illustrates further embodiments of a yarn feeding device. DETAILED DESCRIPTION

In the following a yarn feeding arrangement for a weaving machine will be described. In the figures, the same reference numerals designate identical or corresponding elements throughout the several figures. It will be appreciated that these figures are for illustration only and are not in any way restricting the scope of the invention. Also, it is possible to combine features from different described embodiments to meet specific implementation needs. If the yarn is fed to a weaving machine from a long loose buffer of yarn, the yarn tension will be very low during insertion in to the weaving machine. The buffer of yarn can for example be formed by a number of consecutive loops forming a meandering piece of yarn that can be used during insertion in to the weaving machine.

In Fig. 1 an exemplary yarn feeding device 16 for providing a yarn buffer is shown. The yarn feeding device 16 draws yarn 40 from a yarn storage, here represented by a pre-winder 14. Yarn can also be drawn directly from a bobbin (not shown). The yarn from the yarn feeding device 16 is supplied to a weaving machine 10, here represented by a rapier weaving machine. However, the yarn feeding device can be adapted to feed any type of weaving machine such as an air-jet weaving machine, a water jet weaving machine or a projectile weaving machine, as well as any other suitable type of textile machine. The yarn can thus be taken either directly from a bobbin, or from a conventional pre-winder by the yarn feeding device 16. A loop former 18 of the yarn feeding device 16 winds the yarn onto moving loop keeping members 20, e.g. pins provided on the yarn feeding device. The loop former 18 can be of any suitable design. The loop former 18 will move the yarn from side to side and provide the yarn to the loop keeping members 20. The movement of the loop former 18 can be in a direction essentially perpendicular or at least predominantly perpendicular to the movement of the loop keeping members 20. The movement of the loop former 18 can however in some embodiments deviate from a side to side movement only to better position the yarn on to the loop keeping members. The drive of the yarn feeding device 16 including the drive of the loop former 18 of the yarn feeding device 16 can in accordance with some embodiments be controlled by a controller 19. The controller 19 can in accordance with some embodiments receive input signals from different sensors generally represented by a sensor 17 in Fig 1, and also from the weaving machine 10. This will be described in more detail below. In Fig. 2 some parts of the yarn feeding device 16 are shown in more detail. In Fig. 2 the moving loop keeping members 20 are shown mounted on a roller 22. The moving loop keeping members 20 are moved forward at the same speed as a yarn carrier 24 on which the yarn leaving the moving loop keeping members is laid out. The carrier 24 can be implemented in different ways. For example, he carrier can be one or several endless belts, caterpillar tracks or similar. The carrier 24 is also referred to as yarn carrier or movable yarn carrier herein. In Fig. 2 one endless belt is used as a yarn carrier 24 and is driven by the roller 22, which means that the yarn carrier 24 in this case is driven in synchronism with the loop keeping members 20. The roller is in turn driven by a motor 21. The motor 21 can in particular be a controlled motor. The moving loop keeping members 20 are located and driven in a manner to be accessible for the yarn to be wound by the loop former 18 onto the moving loop keeping members 20. The loop former can be driven by a separate motor 23. In particular the motor 23 can be a controlled motor. The yarn is subsequently released or disengaged from the loop keeping members 20 at a later stage for example by the moving loop keeping members following the roller to get underneath the yarn carrier 24. When the moving loop keeping members are moved under the carrier the yarn will be pushed off the moving loop keeping member and lie free on the carrier. The loops are transported forward in a downstream direction as the carrier 24, in this exemplary embodiment a belt, is driven forward, thus making space for new loops upstream. Downstream the loops are consumed by the weaving machine.

Different yarns will behave in different ways once placed on the carrier 24 as the yarn is released from the moving loop keeping members. Some yarns will stay on the carrier in the same or essentially the same position as the yarn is placed on the carrier. Other yarns have a tendency to twist or move and cause snarls or entanglement when released from the moving loop keeping members. In order to prevent that the yarn moves in an undesired manner, the yarn can be held in position on the carrier by a position keeping means. In Fig. 3 an exemplary embodiment where the position keeping means is formed by a belt or multiple belts. In the embodiment depicted in Fig. 3, where the carrier 24 is a belt (a first, lower, belt), a second, upper, belt 26, moving mainly synchronously with the first belt 24, can be provided. The second belt 26 can be arranged as two parallel belts as shown in Fig. 3. The second belt 26 is located above the first belt slightly distanced from the first belt to make place for the yarn to be placed in-between the first and second belts. If the distance between the first and second belts is small enough the yarn has no space to twist or otherwise make undesired movements. Hence, the distance is preferably smaller than the natural bending radius of a twisting yarn. However, the distance must be big enough to fit the yarn at the thickest portion of the yarn, including knots and splices. In accordance with some preferred embodiments, but not limited to, the distance can be set to be between 1 and 6 mm.

In accordance with some embodiments the moving loop keeping members 20 are pins. Such an embodiment is shown in Fig. 3. The pins 20 can be placed outside the belt or belts 24, 26. The yarn will after release from the pins 20 lie smoothly on the belt 24. When the yarn is wound on the pins 20 the yarn will be stretched between the pins. Once released from the pins 20 the yarn 40 is no longer stretched between the pins 20 and will form loops lying on the belt 24 in a meandering shape.

In an alternative embodiment, the moving loop keeping members such as pins 20 can instead of being placed outside the belt as an alternative be placed in the belt or caterpillar track or a similar carrier. In such an embodiment, a slot 28 (in fig 5) big enough to allow the pin to project through the belt 24 without contacting the belt can be provided.

If the pins are moving in slots, the slot length limits the relation of pin height over the belt and the distance between each pin. For this reason, it can be advantageous to place the pins outside the belt. In Fig. 4 a view illustrating how the loop former 18 wounds yarn 40 onto pins 20 located outside the belt 24 is shown. The loop former 18 winds yarn around one pin 20 at one side of the belt 24 and then travels with the yarn to a pin 20 on the other side of the belt 24. This winding by the loop former continues as the pins moves forward to continuously generate a meandering buffer of yarn lying on the carrier. In Fig. 5 a view illustrating a belt where the pins 20 are located in the belt is shown. The belt is provided with slots 28 to allow the yarn to disengage from the pins. Fig. 5 further also illustrates the limitation with regard to possible pin length / pitch.

Further, as is known some yarns are livelier than other yarns. To keep such lively yarns under control movement restriction means such as brushes and clamps can be used. Such movement restriction means can be fixed to the upper belt if one is provided, or to any other similar arrangement provided to move at the same speed as the carrier that transports the yarn of the yarn buffer. In Fig 3 such a movement restriction means 29 is shown. The yarn is pressed between the movement restriction means and the carrier. An arrangement with movement restriction means can also serve to brake the front part of the yarn loops at the deceleration of a rapier movement in the weaving machine, or at the end of weft insertion of an air-jet or waterjet weaving machine. The properties of the movement restriction means can in accordance with some embodiments be adapted to a specific weaving application. For example, if a heavy yarn is used, the stiffness and/or pressure of the movement restriction means can be selected to be comparatively high, and if a thin yarn is used the stiffness and/or pressure of the movement restriction means can be selected to be comparatively low. The movement restriction means can be of various sizes. For a yarn with a high requirement with regard to controlling the yarn, the movement restriction means can be long, extending from one side of the carrier to the other, or be continuous following the carrier in the moving direction. For other yarns, small movement restriction means placed with distance from each other can be enough to obtain sufficient control of the yarn on the carrier. As the provision of movement restriction means will increase the yarn take-off tension from the yarn feeding device, it is typically preferred to provide as few movement restriction means as possible with as little force against the yarn as possible while obtaining the desired control of the yarn.

The yarn feeding device 16 is controlled to be driven in synchronization with the weaving machine to which it supplies yarn. The yarn buffer formed by the yarn feeding device is controlled to always have a buffer of yarn that can be inserted into the weaving machine. In other words, there will always be some amount of yarn placed on the carrier during operation of the yarn feeding device when feeding a weaving machine. The length of yarn stored on the carrier can be adapted to the speed, the weft pattern and the width of the weaving machine. The width of the loops in the meandering yarn on the carrier, the pitch between each loop and the number of loops possible to store on the carrier determines the length of yarn possible to store in the yarn feeding device. The loop former can be set to wind yarn onto the moving loop keeping members at a speed synchronized with the drive speed of the carrier such that the yarn on the carrier is moved forward at the speed at which yarn is wound onto the moving loop keeping members. The speed at which the yarn is wound onto the moving loop keeping members can be determined in several ways. A standalone solution is to have one or more sensors detecting the yarn, in particular the yarn front, on the belt. The sensor(s) can for example detect the position of the yarn buffer front edge, the amount of yarn taken off from the yarn feeding device or similar information. In particular yarn can be wound onto the moving loop keeping member at the same average speed as the yarn leaves the yarn feeding device. In an alternative embodiment

communication with the weaving machine can be used. Data is fed from the weaving machine. The data can comprise one or more of weaving machine width (pick length), speed (rpm), start & stop of the weaving machine, weft pattern in advance etc. The speed at which the yarn is wound onto the moving loop keeping members is then determined based on data received from the weaving machine. In a further alternative embodiment, the yarn wind on speed control is based on information from both one or more yarn sensors and data received from the weaving machine. The sensor(s) used in the yarn feeding device can be of several types, e.g. optical, mechanical or capacitive. The sensor(s) can be of point type or an array. Alternatively, a camera can be used as a sensor. In accordance with one embodiment where an upper belt is provided, the upper belt can be made as two or more separate belts running side by side at the same speed. The sensor(s) can then be placed in a gap formed between the multiple upper belts. Alternatively, the belts can be more or less perforated, even a mesh structure is envisaged. Hereby the sensors can be adapted to register the yarn from both sides.

The lower belt could potentially be a problem for some sensor types. If for example an optical sensor is used, it may be difficult for the sensor to see the difference between a yarn and the belt. In accordance with one embodiment two or more belts are provided as lower belts and a sensor is located in a gap between the belts. Hereby the quality of the sensor output signal can be improved.

The drive of the yarn feeding device 16 including the loop former 18 can be made by one or more electrical motors. The motors can be individually controlled. If one motor is used, the different drives for the moving parts such as a belt or belts and the loop former can be made via mechanical connections. If separate motors are used, they are advantageously controlled to be driven in synchronization with each other.

The yarn feeding device 16 can be run in single color, weft mix or in free pattern. If a low yarn tension is desired at a location upstream the yarn feeding device, it can be

advantageous to run weft mix of two or more channels so the time to fill the loop buffer is longer, thereby lowering the yarn speed and tension in to the yarn feeding device.

As the carrier is moving forward to fill up the buffer of the yarn feeding device also when the weaving machine connected thereto is not inserting yarn, for example during beat up, or when another channel is inserted, the belt can continue to feed the yarn out from the carrier unless this is prevented. One way to prevent this from happening is to provide an outlet eyelet 34, stationary or movable, before the carrier ends. By doing this the front yarn will be prevented from leaving the carrier and hold back the following loops. For example, when a weft insertion is finished, the yarn buffer is continuously filled up and moved forward by the carrier 24. The moving carrier will then transport not only the yarn loops in the buffer but also the yarn that is between the front loops of the buffer and the weaving machine. To prevent the yarn from leaving the carrier in an uncontrolled way, or even to fall down completely from the carrier, a second yarn movement restriction means can be used. Such a second yarn movement restriction means 32 is shown in Figs. 6a and 6b, where the movement restriction means are exemplified by a brush. Other devices that prevents the yarn from unintentionally leaving the carrier can be used such as a clip or similar. Also shown in Fig. 6a and b is an output guide/eyelet 34 via which the yarn leaves the yarn feeding device 16 to be inserted in to the weaving machine.

Also brake members, e.g. brushes might be placed at the sides of the lower belt to prevent the sides of the loops to be pushed off the belt. Another possibility is to use at least one active member to replace (reshape) some part of the yarn. Such actions to control the yarn located on the carrier can, but need not, be done controlled by input signals from one or more sensors provided.

To lower the yarn tension in to the yarn feeding device, a slip feed device can be placed before the yarn feeding device. The slip feed device is a driven roller that rotates with a peripheral speed that is higher than the necessary yarn speed. Such a device is described in US 5660213. When the yarn feeding device pulls the yarn during the loop formation, the yarn will be pulled against the roller and the friction between the yarn and the rotating roller will contribute to pull the yarn further thus decreasing the yarn tension. As soon as the roller gives more speed to the yarn than what is consumed by the yarn feeding device the force from the yarn against the roller will decrease and hence the pulling force will also decrease until a balance is reached and the roller will not give any further force to the yarn. Fig. 7 depicts an exemplary slip feed device 38 in two different views.

Using a slip feed device in the yarn feeding device as described herein can lower the yarn tension substantially. In Fig. 8 a set-up with a slip feed device 38 before the yarn feeding device 16 is depicted.

In Fig. 9 a flow chart illustrating some steps when controlling a yarn feeding device (16) feeding yarn (40) to a weaving machine (10) is shown. First, in a step 501, yarn is drawn from a yarn storage using a loop former. The yarn can be drawn from a pre-winder or directly from a bobbin or via a slip feed device. Next, in a step 503, yarn is placed in a meandering pattern on a moveable carrier by positioning the yarn on to moving loop keeping members using the loop former. The loop former positions the yarn on the moving loop keeping members by moving the yarn from side to side in a direction perpendicular to a first direction. The moveable carrier and the moving loop keeping members can be designed as described above. The yarn is then in a step 505 transported in the first, forward, direction using the moveable carrier. The yarn lying on the moveable carrier then leaves the moveable carrier at an end section of the moveable carrier in a step 507 to be inserted into the weaving machine.

In Fig. 10 a controller 19 for controlling a yarn feeding device 16 is depicted. The controller 19 can comprise an input/output 81 for receiving input signals for parameters used for controlling the yarn feeding device as set out above. For example, the input signals can be various sensor signals from sensors of the yarn feeding device. For example, sensor signals can be provided from any type of sensor, e.g. optical sensors, mechanical sensors or capacitive sensors. The sensors can be of point type or an array of sensors. Alternatively, a camera can be provided to feed input signals to the controller. Also signals from the weaving machine can be input to the controller 19 and used to control the yarn feeding device. In particular input data from the weaving machine can comprise one or more of weaving pick length, speed (rpm), start & stop of the weaving machine, pattern in advance and similar input data. The input/output 81 outputs motor control signal(s) to controlled motors of the yarn feeding device. The controller 19 further comprises a micro-processor that also can be referred to as a processing unit 82. The processing unit 82 is connected to and can execute computer program instructions stored in a memory 83. The memory 83 can also store data that can be accessed by the processing unit 82. The data in the memory can comprise pre-stored data relating to the weaving machine 10. The computer program instructions can be adapted to cause the controller to control the yarn feeding device comprising a motor in accordance with the teachings herein. The controller can be located at any suitable location. For example, the controller 19 can be integrated in a motor of the yarn feeding device. The controller 19 can input output data using any suitable means. Both wireless and wireline communication devices can be used.

The above examples are for illustration only. Numerous modifications can be envisaged and the different embodiments can be combined to meet specific implementation needs. For example, the moving carrier has been illustrated to be moving yarn horizontally. It is also possible to move the yarn vertically by providing restrictions means to keep the yarn in position during transport on the carrier. Further, in the above examples the loop keeping members 20 are shown as generally cylindrically shaped pins. However, other loop keeping members are also envisaged such as hooks or other elements suitable for engaging the yarn and bring it forward. In Figs 11a and 1 lb an embodiment where the loop keeping members 20 are formed as semi-cylindrical pins is shown. Using semi-cylindrical pins, it is possible to increase the radius of the pins without adding to the space required. Further, a spring biased element 65 can be provided to press the yarn against the loop keeping member from outside the loop keeping member to keep the yarn better in place once placed on the yarn keeping member until the yarn is released from the loop keeping member. The spring biased element 65 can for example be a thin, resilient, metal plate or a similar element. Using the yarn feeding device as described herein will provide numerous advantages. For example, the yarn tension in to a textile machine can be made very low. Also, if a pre- winder is used, the ballooning problem that occurs using a conventional pre-winder is strongly decreased. Generally, the maximum take-off speed from a yarn storage can be significantly decreased. Multiple yarn feeding devices can be used when running a weaving machine in weft mix whereby the yarn speed from the yarn storage can be further reduced.