GB2408053A

GB2408053A - Creating tufts for a loom

Info

Publication number: GB2408053A
Application number: GB0403050A
Authority: GB
Inventors: Neale Bennett; David Bingley
Original assignee: Spencer Wright Industries Inc
Current assignee: Spencer Wright Industries Inc
Priority date: 2003-10-16
Filing date: 2004-02-11
Publication date: 2005-05-18
Anticipated expiration: 2024-02-11
Also published as: GB0403050D0; GB2408053B; GB0324277D0

Abstract

A method of creating tufts for a loom, comprises the steps of supplying a plurality of yarns Y from respective yarn holders 1, moving the yarn holder across yarn receiving sites 32 of yarn collector 30, inserting a yarn at a selected yarn receiving site and holding it in place and withdrawing the yarn holder to draw off a length of yarn which is then cut using blade 52 to leave a tuft (T, Fig 2F). The apparatus is also disclosed.

Description

A METHOD AND APPARATUS FOR CREATING TUFTS FOR A LOOM

The present invention relates to a method and apparatus for creating tufts for a loom.

WO 95/31594 discloses an apparatus for creating tufts.

In order to do this, a yarn collector is provided with a number of yarn receiving sites spaced across the collector.

Above the yarn collector are a plurality of tuft forming means. The tuft forming means are arranged in a number of sets, each set having a yarn of each of the different colours to be used in the weaving process. The yarn collector is indexed across beneath the tuft forming means until a yarn receiving site is below the colour of the yarn that, according to the patterning information, it is required to have. Once it is in this position, the tuft forming process is carried out.

In order to form each tuft, a pivotal body moves against the stationary element with a finger on the pivotal body forcing the yarn into a slot in the stationary element.

The size of the tuft is determined by the depth of penetration of the finger into the slot. This effectively creates a slack portion of yarn which is then released and is forced to the yarn forming site by a flow of high pressure air. Here the yarn is trapped in position. The yarn is held in position while movement of the pivotable body brings the yarn into contact with a blade thereby severing the yarn and forming an individual tuft. The tuft can then be removed by a gripper. The mechanism required to do this is complex, and the use of the high pressure air to feed the slack yarn means that positive control of the yarn - 2 at this time is not possible. Also, each tuft forming means is required to have its own drive to draw off a length of yarn. This document also discloses the possibility of a fixed yarn collector across which the tuft forming means is traversed. This is in the context of a double tuft carrier which is rotated between loading and unloading positions.

However, no detail is given on how this should be done.

A development of this invention is disclosed in GB 2355993. In this document, the air feed system is replaced by a rotating toothed wheel which grips the yarn and feeds it to the required extent. This provides a greater degree of control over the end of yarn. However, the mechanism is still complex and a motor is required for each yarn feed.

A more practical proposition is provided by WO 01/88240 and WO 01/88241. These documents disclose an apparatus for creating tufts in which the tuft carrier is stationary and the tuft forming device is indexed across it. Each tuft forming device is provided with a selector wheel to allow each device to supply a plurality of yarns of different colours. When a yarn is selected, a tuft is cut. The cut tuft is then transferred into the required position on the tuft carrier either by a flow of air, or by a pusher. As the machine relies on the movement of cut tufts from one location to another without the tuft being positively held, there will be problems with the cut tufts not being transferred to the desired location at the level of reliability required for a commercial weaving machine.

A further example of a tuft forming apparatus is disclosed in WO 02/24994. Again, this has a stationary tuft - 3 carrier across which a tuft forming apparatus is traversed.

Each cut tuft is pushed downwardly by a gripper which slides along a surface and into a groove which is narrow enough to retain the tuft in position. Again, this document relies on moving a cut tuft of yarn into a yarn carrier. In practice, pushing a cut end of yarn lengthwise along a surface will strip the filaments from the yarn. This problem will be exacerbated by attempting to push the cut end lengthwise into a narrow slot.

The present invention therefore addresses the problem of providing a method and apparatus of creating tufts for a loom in which the movement of cut tufts of yarn to a yarn receiving site is not necessary.

According to the present invention there is provided a method of creating tufts for a loom, the method comprising the steps of supplying a plurality of yarns each in a respective yarn holder, indexing the yarn holders across a yarn collector having a plurality of yarn receiving sites, inserting a yarn at a selected yarn receiving site and holding it in place, withdrawing the yarn holder for the inserted yarn to draw off a length of yarn, and cutting the length of yarn to leave a tuft held in the selected yarn receiving site.

As the yarn is inserted at the yarn receiving site, before the length of yarn is drawn off and cut, the need to manipulate a cut end of yarn to the yarn receiving site is removed. Therefore, the present invention offers significantly greater reliability than the prior art.

Each yarn holder may be driven by its own dedicated drive. However, preferably, a common drive member is provided for withdrawing the yarn holders, and the method further comprises the step of selectively latching each yarn holder to the common drive member to allow the latched yarn holder to form a tuft. With this arrangement, a single drive and a latching mechanism can replace the requirement to have a drive motor at each yarn receiving site thereby simplifying the structure.

The yarn may simply be held by being an interference fit in the yarn collector. However, preferably, the method further comprises clamping a yarn held in a yarn receiving site with a separate clamping number.

The yarn may be cut with the yarn held just at the yarn receiving site. However, preferably, the method comprises the step of securing each yarn which is inserted in the selected yarn receiving site at a second yarn holding location spaced from the yarn receiving site. This affords greater control of the yarn as it is cut and prevents it interfering with successive selections.

The yarn may be held at the second location by any suitable means, such as a separately movable clamping member. However, preferably, the method further comprises a step of moving the yarn holder in a direction substantially perpendicular to the direction in which the yarn holder is withdrawn to insert the yarn into a holder at the second yarn holding location. - 5 -

In order to relax the yarn in the tuft carrier, the method preferably comprises the step of moving the yarn holder back towards the second yarn holding location once the yarn is secured at the second holding location in order to relax the yarn above the second yarn holding location prior to the cutting step.

Preferably, the cutting step occurs at a location adjacent to the second yarn holding location. Preferably the method of the present invention further includes the step of moving a knife past a plurality of yarn holders in order to sever a number of held yarns in a single movement.

According to a second aspect of the present invention there is provided a tuft handling apparatus for a loom, the apparatus comprising a plurality of yarn holders each supplying a yarn, a yarn collector with a plurality of yarn receiving sites each for receiving a yarn from a selected yarn holder, a cutter to cut the yarn held by the yarn receiving site to form a tuft of yarn held at the yarn receiving site, wherein the yarn holders are movable across the yarn collector to allow a yarn holder to selectively be brought into alignment with different yarn receiving sites, and are movable away from the yarn holder, with the yarn inserted in a yarn receiving site to draw off a length of yarn.

An example of a method and apparatus in accordance with the present invention will now be described with reference to the accompanying drawings, in which: - 6 Fig. 1 is a cross-section through a tuft handling apparatus; Figs. 2A-2H show a detail from the lower part of the apparatus of Fig. 1 demonstrating the tuft forming process.

The apparatus shown in Fig. 1 is centred around yarn holders 1. One of these is illustrated in Fig. 1, although, in practice, for each tuft forming device, there will be one yarn holder for each colour of yarn being used for a particular set of yarn holders in the tuft handling apparatus. The yarn holders are spaced perpendicular to the plane of the page of Fig. 1.

Each yarn holder extends from a top end 2 to a bottom end 3 which is shown more clearly in Figs. 2A-2H. The upper part of the assembly of Fig. 1 is dedicated to providing movement of each yarn holder 1 along three orthogonal axes and will now be described with reference to Fig. 1. The action of each yarn holder 1 to form a tuft will then be described with reference to Figs. 2A-2H.

In a subsequent description, the orthogonal axis system is as follows. The X axis is across the page in Fig. 1, the Y direction is perpendicular to the page in Fig. 1, and the Z direction is up and down the page and corresponds, in practice, to the vertical direction.

A yoke 4 is provided to which the yarn holders 1 can be selectively latched by a plurality of pneumatically operated latches 5. Fig. 1 shows three such latches arranged vertically. This has been done in order to accommodate the - 7 - necessary pitch for the yarn holders 1. In practice, each of the three latches cooperates with a different yarn holder. Each latch has a piston 6 which, when extended, enters a slot 7 in the top end 2 of the yarn holder 1 such that the yarn holder is then latched to move with the yoke 4.

The yoke 4 is moved in the X direction by a motor (not shown) along guide rails 8. The yoke 4 is also reciprocally driven in the Z direction by a motor (not shown) along guide rails 10, 11. This whole mechanism is movable in the Y direction by a motor (not shown) along rails 12.

As a result of this arrangement, the entire mechanism described above may be indexed along the rails 12 in the Y direction to allow the yarn holders 1 to be shifted laterally. When it is determined that a yarn holder 1 is required to produce a tuft (as described below) it is selected by a control system which fires the appropriate latch 5, thereby latching the yarn holder 1 to the yoke 4 allowing it to be reciprocated in the X and Z directions.

The rest of the yarn forming mechanism will now be described with reference to Fig. 2A.

The lower end 3 of the yarn holder 1 is fed with a yarn Y. The yarn passes through a yarn latch consisting of a plate 20 and a spring loaded pawl 21 which allows yarn to flow down through the clamp and prevents movement in the opposite direction. - 8

The yarn forming apparatus consists of a number of other components as shown in Fig. 2A. A yarn collector 30 is provided with a collector comb 31 having a number of yarn receiving sites 32 spaced in the Y direction. Essentially, each yarn receiving site is a groove which has a V-shaped section when viewed from above.

A plurality of yarn clamps 40 are similarly spaced in the Y direction. Each yarn clamp faces a yarn receiving site 32 and has an extendable piston 41 which is reciprocally movable in the X direction.

Above the collector comb 31 is a knife comb 50. As with the collector comb, the knife comb 50 has a number of yarn receiving sites 51 each of which is positioned directly above the corresponding yarn receiving site 32. A knife blade 52 has a cutting edge 53 and is movable across the top of the knife comb 50 in the Y direction.

The formation of a single tuft will now be described with reference to Figs. 2A-2H.

Fig. 2A shows the elements of the yarn forming apparatus and their relative positions at the start of the tuft forming cycle. In this position, the yarn holders 1 are indexed in the Y direction until a yarn holder 1, having the appropriate colour yarn for a particular yarn receiving site 32 is in line with yarn receiving site 32. At this time, the yarn holder 1 is latched for reciprocation as mentioned above. - 9

As shown in Fig. 2B, yarn holder 1 moves vertically downwards in the Z direction to position the end of yarn Y between the yarn receiving site 32 and piston 41. The yarn latch ensures that the yarn Y is drawn down with the yarn holder 1.

As shown in Fig. 2C, the piston 41 of the yarn clamp 40 is then extended to force the yarn Y into the yarn receiving site 32.

As shown in Fig. 2D, the yarn holder 1 moves vertically upwardly in the Z direction. As the yarn is secured in the collector comb 31, a length of yarn is drawn off.

As shown in Fig. 2E, as the yarn holder 1 moves in the Z direction, it is also moved to the right as shown in Fig. 2E generally in the X direction, and this has the effect of bringing the yarn Y into the yarn receiving site 51 in the knife comb. Movement of the yarn holder 1 is stopped when the yarn extends vertically as shown in Fig. 2E. The yarn holder 1 then moves downwards slightly to relax the yarn above the knife comb 50 before it is cut.

As shown in Fig. 2F, the knife 52 is then moved across the top of the knife comb 50 in the Y direction so that the yarn is cut between the knife edge 53 and the top of the knife comb 50 to form a tuft T. As shown in Fig. 2G, the yarn holder 1 is then withdrawn in the X direction to its original starting position where it can again be indexed in the Y direction. - 10

The patterning requirement of the carpet will require a tuft of a certain colour to be deposited at each of the yarn receiving sites 32. The yarn holders 1, each of which carries a different colour of yarn, are indexed across the collector comb 31 and the tuft forming process is carried out for each site when the appropriate colour is aligned with the site. It will therefore be understood that, in certain indexed positions, tufts will be formed at more than one yarn receiving site 32 simultaneously if it should happen that the yarns for the appropriate colour for more than one site are aligned with their respective sites at the same time. Also, there will be certain indexed positions in which no yarns are aligned with the appropriate site, in which case the yarn holders 1 will remain unselected and will then index to the next position.

When all of the yarn receiving sites 32 are filled with tufts, grippers 60 swing into position to grip the lower end of each tuft as shown in Fig. 2H. Each piston 41 of the yarn clamps 40 will return to its original position allowing the gripper to move away taking the tufts with it. When the tufts are clear, the cycle will begin again.

A sensor (e.g. an optical sensor) may be employed at each yarn receiving site 32 to verify that a tuft has been created as desired. If the sensor detects the absence of a tuft when one should be present, the yarn holders 1 may be indexed back to replace the missing tuft.

In order to change the tuft length, the distance that the yarn holders 1 are moved to draw off the yarn is - 11 changed. The distance between the yarn collector 30 and knife comb is then adjusted accordingly. - 12

Claims

1. A method of creating tufts for a loom, the method comprising the steps of supplying a plurality of yarns each in a respective yarn holder, indexing the yarn holders across a yarn collector having a plurality of yarn receiving sites, inserting a yarn at a selected yarn receiving site and holding it in place, withdrawing the yarn holder for the inserted yarn to draw off a length of yarn, and cutting the length of yarn to leave a tuft held in the selected yarn receiving site.

2. A method according to claim 1, wherein a common drive member is provided for withdrawing the yarn holders, and the method further comprises the step of selectively latching each yarn holder to the common drive member to allow the latched yarn holder to form a tuft.

3. A method according to claim 1 or claim 2, further comprising clamping a yarn held in a yarn receiving site with a separate clamping number.

4. A method according to any one of the preceding claims, wherein the method comprises the step of securing each yarn which is inserted in the selected yarn receiving site at a second yarn holding location spaced from the yarn receiving site.

5. A method according to claim 4, wherein the method further comprises a step of moving the yarn holder in a direction substantially perpendicular to the direction in which the yarn holder is withdrawn to insert the yarn into a holder at the second yarn holding location.

6. A method according to claim 4 or claim 5, further comprising the step of moving the yarn holder back towards the second yarn holding location once the yarn is secured at the second holding location in order to relax the yarn above the second yarn holding location prior to the cutting step.

7. A method according to any of claims 4 to 6, wherein the cutting step occurs at a location adjacent to the second yarn holding location.

8. A method according to any one of the preceding claims, further including the step of moving a knife past a plurality of yarn holders in order to sever a number of held yarns in a single movement.

9. A tuft handling apparatus for a loom, the apparatus comprising a plurality of yarn holders each supplying a yarn, a yarn collector with a plurality of yarn receiving sites each for receiving a yarn from a selected yarn holder, a cutter to cut the yarn held by the yarn receiving site to form a tuft of yarn held at the yarn receiving site, wherein the yarn holders are movable across the yarn collector to allow a yarn holder to selectively be brought into alignment with different yarn receiving sites, and are movable away from the yarn holder, with the yarn inserted in a yarn receiving site to draw off a length of yarn. - 14

10. An apparatus claim according to claim 9, further comprising a common drive member for withdrawing the yarn holders, and a latching assembly to selectively latch each yarn holder to the common drive member to allow the latched yarn holder to form a tuft.

11. An apparatus according to claims 9 and 10, further comprising a clamping member to clamp the yarn held in a yarn receiving site.

12. An apparatus according to any one of claims 9 to 11, further comprising a second yarn holding location spaced from the yarn receiving site at which each yarn is secured.

13. An apparatus according to claim 12, further comprising a mechanism to move the yarn holder in a direction substantially perpendicular to the direction in which the yarn holder is withdrawn to insert the yarn holder at the second yarn holding location.

14. An apparatus according to claim 12 or claim 13, further comprising a mechanism to move the yarn holder back towards the second yarn holding location once a yarn is secured at the second yarn holding location.

15. An apparatus according to any one of claims 12 to 14, further comprising a knife at a location adjacent to the second yarn holding location.

16. An apparatus according to claim 15, further comprising a mechanism for moving the knife past a plurality of yarn holders in order to sever a number of held yarns in a single movement.