GB2145438A - False twist device - Google Patents

Abstract

A false twist device has a yarn engaging member or a yarn engaging passage (8) mounted in, or on, an insert (10) of resilient material. The device may then be resiliently attached to a part of a textile machine and will be securely retained even if rotated at high speeds. <IMAGE>

Description

SPECIFICATION Improvements in and relating to textile machines This invention relates to textile machines and in particular to false twist devices for use therein.

False twist devices are often used in conjunction with textile machinery to impart a false twist to textile yarn or sliver normally to help to provide fibre adhesion or control of drafting or to condense the sliver for binding into a wrap yarn.

The false twist device may have to be changed to suit the processing of different materials or be replaced through wear or damage and it is therefore necessary for the change to be made as quickly as possible, so as not to impair the production efficiency of the machine. The fact that the spindles to which the false twist is connected may, in some applications, rotate at very high speeds e.g. 30,000 r.p.m., with each machine incorporating for example a hundred or more spindles, make it essential that the false twist devices are well secured to the spindle for if one became detached at such a high speed this could badly injure or even kill a person in the path of the loose device.

False twist devices are usually made of steel, some incorporating wear resistant inserts, or sometimes they consist solely of a suitable shaped wire which causes the yarn to deviate from its path so as to apply the necessary false twist to it. The wire may, for example, be 'V' shaped and the yarn may be spiralled one or more times around it. However, such designs have been found to be unsatisfactory at high speeds with certain materials as they do not consistently keep control over the level of twist in the sliver or yarn which periodically slips and gulps hence resulting in varying characteristics along the length of the end product, e.g. a wrap spun yarn.

It is, therefore, a general objective of this invention to develop a suitable false twist device which: (i) provides consistently good false twist control over the materials being processed.

(ii) may be easily attached to and removed from the spindle or housing while being safely secured to it during rotation.

(iii) is comparively inexpensive.

A false twist device in accordance with the invention has a yarn engaging member, or yarn engaging passage, mounted in or on an insert of resilient material.

The expression "yarn" is intended to encompass any textile material on which the false twist device is being used.

The yarn engaging member may be in the form of a tube, which may be of glass, to provide a tortuous path for the yarn and which may be moulded into the insert.

The resilient insert which may be of rubber or a suitable plastics material may be formed with a projection or recess to engage with a cooperating recess or projection on the mounting for the insert which may be for example an extension of, or be part of, a spindle of a spinning machine, so as to retain the insert in position at high speeds.

Such a false twist device is believed to satisfy the objectives set out above and provides an improvement in the quality of the yarn.

Such a false twist device is particularly useful, although not exclusively, for use with a wrap spinning machine.

Wrap spinning is a process in which a core of textile material is passed through a high speed rotary spindle carrying a package of wrapper yarn which is withdrawn over-end from the package and is wound around or twisted together with the core as a result of the rotation of the spindle so as to bind the core to give a coherent yarn. The core material may take various forms, but is most commonly constituted by a sliver delivered directly from a drawing head so that the drafted sliver proceeds directly from the delivery roller to the entrance of the axial bore of the rotary spindle. The wrapper yarn may comprise, for example, mono-or multi-filaments, tapes or natural or synthetic yarn.

Wrapped yarn produced in this way can be used for a variety of purposes, e.g. upholstery fabrics and carpet yarns, and its characteristics can be varied as required. For example, effect yarns can be produced by overfeeding an effect component to join with the core material prior to the rotary spindle. The effect component may be another sliver or yarn which is fed at a varying rate to that of the core material so as to give a knobbly appearance.

The apparatus necessary for carrying out such a process generally comprises drafting delivery rollers, a take-up roller(s) and one or more hollow spindles which serve as a support for a package or packages of wrapper yarns. The spindles are located between the delivery and take-up rollers and are driven at very high speeds. Either one, or both of the spindles may include a false twist device which rotates at the same speed as the spindle, although it would be possible to fit the false twist device separately from the spindle and drive it at a different speed from the spindle. The false twist device is usually fitted either at the entry end or the exit end of the spindle. If a false twist device is not incoropoated the wrapper yarn simply winds around the core, but when one is fitted the core and the wrapper twist together.

The core and effect materials, if any, pass from the drafting head to the spindle which normally carries the false twist device at its entry or exit end, more usually the latter. The false twist device may be a frictional type which relies on its rubbing contact with the yarn to twist it or it may be a more positive type around which the yarn has to bend so as to deflect it from the straight line path and hence hold it sufficienly firmly to twist it about its axis while yet allowing it to run smoothly through the false twist device. The latter type gives a more constant level of twist.

The sliver core will be twisted one hand between the false twist device and the delivery rollers, i.e. the upstream side of the false twist device, while on the downstream side the twist will reverse to the opposite hand. In practice, as the wrapper yarn and the core material leave the false twist device, the twist that has been inserted into the core on the upstream side starts to untwist and, in so doing, causes the wrapper yarn and the core material to twist together to form the yarn. In practice, there is some degree of wrapping of wrapper yarn and the core prior to the false twist device if the false twist device is fitted at the exit end of the spindle.This comes about mainly by reason of the unwinding revolutions of the wrapper from its supply package around the axis of the spindle but this is quite incidental to the end result and the effective wrapping, i.e. twisting of the wrapper yarn and the core material occurs as the two leave the false twist device.

The yarn may, of course, be double wrapped by passing it through two spindles and in our particular machine which has a double spindle arrangement, only the first spindle is fitted with a false twist device so that as the once wrapped yarn passes through the second spindle the wrapper yarn merely winds around the other two rather than twisting together with it as is the case when the false twist device is used. It will be appreciated that the direction of rotation of the spindles can be arranged so that the wrappers are run in opposite hands.

An example of a false twist device in accor- dance with the invention will now be described by way of example with reference to the accompanying sketch drawing in which: Figure 1 is a diagram of a foreshortened spindle of a yarn spinning machine; Figure 2 is an elevation of a modified false twist device in accordance with the invention; Figure 3 is a plan view of the device shown in Fig. 2, Figure 4 is a plan view of a further alternative device, and Figure 5 is a sectional elevation of a yet further alternative device.

Referring to Fig. 1, the spindle 2 of a wrap spinning machine, not illustrated, has an axial passage 4. A pulley 6 is firmly pressed on to the bottom of the spindle to receive, for example, a belt drive for rapid rotation of the spindle.

The pulley is hollow and a glass tube 8 and having the shape of a wave constituting a yarn engaging member, so as to be able to grip yarn passing through the spindle is mounted in an insert 10 of resilient rubber or plastic-like material such as that known as Vulkollan.

The tube is moulded into the insert and the insert is formed with an integrally moulded annular ring 12, see Fig. 2, and a collar 14.

The ring 12 is located in use in an annular groove 16 formed on the inside wall of the pulley 6. When the insert 10 is pressed into position the resilient material from which it is made enables it to be pushed along the side of the pulley extension 6 until the ring 1 2 snaps into the groove 1 6 and the inside face of the collar 14 abuts against the end of the pulley.

Because of the resilience of the insert, the false twist device is securely held in place and the centrifugal forces set up by high speed rotation of the spindle ensures there is no compaction of the insert and indeed the higher the speed of the spindle, the more secure the connection between the insert of the hollow pulley becomes.

However, the insert may be very readily removed from a stationery spindle and replaced with a new insert and tube forming the false twist device as and when required.

The alternative false twist device illustrated in Figs. 2 and 3 has an annular recess 1 8 moulded into the insert which extends just beyond the position of the annular ring 12.

This helps to increase the resilience of the insert and indeed the connection between the insert and the pulley tube during use.

In the further modification illustrated in Fig.

4, the annular recess 1 8 is dispensed with and the insert body is separated into four quarters by cuts 20 for a length greater thar the distances from the outside of the coilar to the annular ring 12 as illustrated in Figs.

and 2. This helps to increase the resilient connection between the insert and the bore of the pulley during operation.

In order to prevent any possibility of the insert being rotated within the pulley, the insert or spindle wall may be formed with a dimple which engages a corresponding protrusion on the other member. If this protrusion is on the inside wall of the pulley, it may press into the resilient insert without the necessity of forming a dimple on the insert depending on the resilience of the insert material.

As can be seen from Fig. 1, the glass tube 8 is formed at each end with a short portion 22 which is concentric with the axis of the spindle while the central portion is in the form of tangential curves.

This has been found to be particularly effective in gripping the sliver and wrapping yarn firmly so as to false twist it, but yet without any abrasiveness on the fibres and has led to excellent spinning results.

Alternatively the tube may, for example, be of any wear-resistant material, e.g. ceramic, although this is more expensive. Although it is preferable that the false twist element, e.g.

the tube, is continuous, it may comprise more than one part.

The retention element need not necessarily be in the form of an annular ring but may be any abutment which will snap into place with a cooperating recess and the abutment may be in the insert or the spindle (pulley) bore.

It will of course be appreciated that in the very unlikely event of the insert becoming detached, for example, by reason of it not having been pressed correctly into position, the fact that the insert is manufactured from a rubbery material considerably reduces any likelihood of it seriously injuring the operator.

The embodiment illustrated in Fig. 5 comprises a resilient mounting 10 which can be pressed into the interior of the spindle pulley and which has a ceramic tube through its centre along which the yarn may pass to a false twist device in the form of a steel wire bent into a V-shape 24. The yarn then makes a turn around one of the legs of the 'V' and passes downwardly to the draw-off rollers. It is this twisting of the yarn around the 'V' which actually gives the false twist to the yarn but if a greater grip on the yarn is desired the tube may also provide a tortuous yarn path such as is shown in Fig. 1. The wire is moulded into the resilient insert.

Claims (7)

1. A false twist device having a yarn engaging member or a yarn engaging passage, mounted in or on an insert of resilient material.

2. A false twist device as claimed in Claim 1 in which the yarn engaging member is in the form of a tube providing a tortuous path for the yarn.

3. A false twist device as claimed in Claim 2 in which the tube is moulded into the resilient insert.

4. A false twist device as claimed in Claim 1 in which the yarn engaging member is in the form of a wire bent into a V-shape, the wire being mounted in or on the resilient insert.

5. A false twist device as claimed in any one of the preceding claims in which the resilient insert is formed with a projection or recess to correspond with a recess or projection on a mounting for the insert.

6. A wrap spinning maching having a false twist device as claimed in any of the preceding claims positioned either at the entry end or exit end, of a spindle of the machine.

7. A false twist device substantially as hereinbefore described with reference to any one of Figs. 1, 2 and 3, 4 or 5 of the accompanying drawings.