GB2136461A - Yarn-handling process and apparatus - Google Patents

Abstract

A yarn storage device before a yarn splicer (4) comprises a rotating foraminous cylinder (1) defining on its exterior a cylindrical yarn-storage surface which passes a suction slot (3) within the cylinder, to assist build-up of delivered yarn on the surface of the cylinder in the form of staggered loops of stored yarn. On take-up of the stored yarn, the first-laid loops are removed from the cylinder (1) ahead of the later-laid loops. A shallow slot (7) provides reduced suction to retain the loops, and an optional slot (9) provides back tension during loop removal. A broken yarn end may be fired at the cylinder by rollers 5, 6. The cylinder may be raised to meet the yarn. <IMAGE>

Description

SPECIFICATION Yarn handling process and apparatus The present invention relates to yarn handling and in particular to a process and apparatus for facilitating joining of two lengths of yarn ''on-the-fly'' .

There are various known methods of joining two lengths of yarn, such as splicing, knotting and glueing, and many other techniques of less widespread application. The task of joining two lengths of yarn is made more complicated when this is to be carried out "on-thefly" because there is usually one of the lengths which is stationary and attached to a winder, and another length which is being delivered continuously and is therefore moving. The longer the time taken by the joining technique, the greater the amount of the second length which has been delivered during the joining operation, and consequently the more likelihood there is of snarling when yarn takes up.

One method, used hitherto in continuous filament yarn handling, employs the suction gun or aspirator which can be used to entrain a loose end, thereby facilitating piecing up.

However, where yarn is to be joined, the scope for yarn storage using such an aspirator is very limited because the free end of the yarn length must be used for the joining operation and if the "second length" is still being drawn into the aspirator during its continued delivery then there is a considerable risk of tangling and snarling of the yarn when eventually the join has been made and the stored yarn is wound up.

It is an object of the present invention to provide for the handling of yarn by storing a length of yarn "on-the-fly" with improved storage capacity. Such improved capacity is, for example, necessary when the delivered yarn is being produced by high speed spinning of staple yarn.

Accordingly a first aspect of the present invention provides a yarn handling process, comprising providing a yarn-storage surface, applying spun yarn to the storage surface to form a build-up of a succession of serially connected loops of the stored yarn on the yarn-storage surface, the loops being formed in sequence, and subsequently removing the stored yarn loops in the same sequence as that in which they were laid.

A second aspect of the present invention provides a yarn handling process comprising providing a yarn storage surface, applying the spun yarn to the yarn storage surface and attracting it onto the surface by suction at a first level to form a build up of a succession of serially interconnected loops of the stored yarn on the surface; holding the loops on the surface by suction at a second level weaker than the first level; then removing the loops against the attraction of suction which induces back tension in the yarn, wherein the loops are formed in a given sequence and are removed from the surface in the same sequence.

A third aspect of the invention provides a yarn handling device comprising a yarn-storage surface, and means for laying stored yarn on the storage surface as a succession of staggered loops from which the first-laid convolutions can be withdrawn before the laterlaid convolutions.

A fourth aspect of the present invention provides a yarn handling device comprising a foraminous yarn storage surface, means for laying stored yarn on the storage surface as a succession of staggered loops, means for applying suction at a first level to the surface as the said loops are formed and means for applying suction at a weaker level to the surface after the loops have been formed, to hold them in place.

In order that the present invention may more readily be understood the following description is given, merely by way of example, of one embodiment of yarn handling apparatus in accordance with the present invention, reference being made to the accompanying drawing in which the sole figure shows a transverse sectional view of a yarn storage drum of the yarn handling apparatus.

Fig. 1 shows a foraminous yarn storage drum 1 on which external yarn reservoir loops 2a of a yarn length 2 are allowed to form and are spaced around the periphery of that drum by virtue of rotation of the drum. The attraction of the yarn onto the external surface of the drum is achieved by means of a suction passage 3 in the form of a slot running parallel to the longitudinal axis of the drum and subtending at the centre of the drum only a relatively small angle in comparison with the 360 circumference of the drum. This ensures that intensive suction is applied to the holes in the drum surface around the location 1 a at which the yarn loops form, the loops then remaining in place as the drum rotates, by virtue of attenuated suction and the effect of gravity holding the yarn on the drum.

In use of the apparatus illustrated, when a break occurs (either naturally or when changing yarn packages during winding) the moving loose end being delivered lands on the drum 1 to make contact with it at location 1 a in register with the suction slot 3. For example, the yarn may be "fired" at the drum surface by the delivery rollers 5, 6 shown schematically in the drawing. The drum 1 may be movable up into the yarn path from below, in order to make contact between the yarn and the drum.

A yarn splicer is shown schematically at 4 in the drawing. The two delivery rollers may for example be fed with yarn from a spinning machine, preferably a high speed spinner such as a rotor spinner, a friction spinner or a jet spinner.

The natural twist in the spun staple yarn issuing from an upstream spinner causes it to fall naturally onto the drum surface in serially connected loops which overlap each other in a non-concentric manner (in other words each loop is displaced very slightly from the preceding loop, etc.).

This staggering of the loops is induced by rotation of the drum and the arrangement will normally be such that the location 1 a of the drum surface where the spun yarn 2 forming the loops 2a impinges, will always be in register with the suction slot 3.

The above-mentioned attenuated suction to retain the yarn on the surface of the foraminous drum 1 is achieved by means of a reduced radius portion of the drum extending along the direction of rotation of the drum starting from the suction slot 3 at which the yarn-attracting suction is applied to the surface of drum 1. This reduced radius portion defines, with the foraminous wall of the drum 1, a passage 7 of small radial extent which communicates with the suction from suction slot 3 so that whereas the full suction from the manifold 8 within the core of the drum is applied at region 1 a of the surface of drum 1, the suction applied by way of the thin passage 7 is attenuated by virtue of the flow throttling affect of the passage 7.

The drawing also shows a further suction slot 9 communicating suction from the manifold 8 to the yarn withdrawal region 1 C of the drum, in order to apply fierce suction to the yarn at the withdrawal zone to provide a back tension which facilitates take-up of the yarn, for example after splicing.

It may be advisable for the yarn-attracting suction at region 1 a to be more intense than the back tension-inducing suction at region 1 c, in which case the cross-section of slot 3 will be greater than the cross-section of slot 9, which is in turn going to be greater than the flow cross-section of the passage 7 providing the attenuated suction in the yarn-storage region 1 b.

As a further possible alternative, the arrangement may be such that the passage 7 supplies sufficient suction both to hold the yarn on the yarn storage regions 1 b of the drum 1, and also to provide sufficient back tension to facilitate wind-up, in which case the second suction slot 9 can be dispensed with.

As soon as splicing of free end 2' has been achieved, the new package winding operation starts and the yarn will then begin to be withdrawn from the surface of the drum 1 with the lowermost coils (the first coils to have formed on the drum exterior) being the first withdrawn away. The sequence of yarn loop withdrawal is therefore the same as the sequence in which they were formed. The staggering of the respective convolutions of the looped build-up allows this to take place without snarling of the yarn.

Although the present invention provides description of a main embodiment using spinning, it will be appreciated that any other yarn delivery device can supply the yarn to the storage apparatus in accordance with the present invention, and likewise the take-up of yarn from the yarn-storage surface can be subsequent to yarn joining using any technique, not necessarily yarn splicing (for example an adhesive joiner or a yarn knotting device may be used).

Instead of being on the foraminous drum illustrated in the drawing, it is possible for the yarn-storage surface to be formed on a foraminous conveyor belt moving over a suction slot, or on a reciprocating surface having a traverse in a first direction which takes long enough to accumulate the desired quantity of yarn delivered during the joining operation or other yarn handling operation (which is carried out "on-the-fly" with the assistance of the apparatus in accordance with the present invention).

The process of yarn storage in accordance with the present invention provides a particularly convenient manner of accumulating a build-up of delivered yarn, and nevertheless allowing immediate take-up of that stored yarn when desired.

It will of course be understood that upon resumption of yarn winding, the yarn storage operation will initially continue but the rate of winding will be such that the number of convolutions of stored yarn on the foraminous surface at any one time will reduce until eventually a straight line yarn path between the delivery device (in this case the spinner) and the take-up device (in the preferred embodiment the winder) exists.

The application of suction to hold the yarn on the storage surface is not essential. Any other means can be provided which holds the stored convolutions, preferably such that the first-formed convolutions can be the first taken up by the winder, preferably without disturbing the later-formed convolutions.

Claims (19)

1. A yarn handling process comprising providing a yarn-storage surface, applying spun yarn to the storage surface to form a build-up of a succession of serially connected loops of the stored yarn on the yarn storage surface, the loops being formed in sequence, and subsequently removing the stored yarn loops in the same sequence as that in which they were laid.

2. A yarn handling process comprising providing a yarn storage surface, applying spun yarn to the yarn storage surface and attracting it onto the surface by suction at a first level to form a build up of a succession of serially interconnected loops of the stored yarn on the surface; holding the loops on the surface by suction at a second level weaker than the first level; then removing the loops against the attraction of suction which induces back tension in the yarn, wherein the loops are formed in a given sequence and are removed from the surface in the same sequence.

3. A yarn handling process according to claim 1, wherein the loops are formed with the later-laid loops on and partially overlapping the earlier-laid loops.

4. A yarn handling process according to claim 1 or 3, wherein the formation of the loops of stored yarn on the yarn-storage surface is assisted by the application of suction to the rear of a foraminous member defining the yarn-storage surface.

5. A yarn handling process according to claim 4, wherein the suction is applied at a first level to attract the yarn to the surface to form the looped build-up and subsequently the section is reduced to a second weaker level.

6. A yarn handling process according to claim 2 or claim 5, wherein the suction is held at said second level to maintain the looped build-up of stored yarn on the surface and is subsequently increased to a third level between the first and second levels to generate back tension as the yarn is removed from the surface.

7. A yarn handling process according to claim 4, 5 or 6, wherein the member defining the yarn-storage surface is continous and rotates continuously, during which rotation of the loops of stored yarn are sequentially built up on the exterior of said continuous foraminous member.

8. A yarn handling process according to any one of claims 1 to 7, wherein the loops are formed by the inherent twist in the yarn as the yarn is laid on the yarn-storage surface.

9. A yarn handling device comprising a foraminous yarn-storage surface, means for laying stored yarn on the storage surface as a succession of staggered loops from which the first-laid convolutions can be withdrawn before the later-laid convolutions, and means for applying suction behind the foraminous member to attract yarn being laid onto the yarnstorage surface.

10. A yarn handling device comprising a foraminous yarn storage surface, means for laying stored yarn on the storage surface as a succession of staggered loops, means for applying suction at a first level to the surface as the said loops are formed and means for applying suction at a weaker level to the surface after the loops have been formed, to hold them in place.

11. A yarn handling device according to claim 10, wherein said yarn-laying means includes means for moving the yarn-storage surface relative to a storage location to stagger the various loops of yarn.

1 2. A yarn handling device according to claim 10, 11 or 12, wherein the yarn-storage surface comprises the external surface of a hollow cylinder, with the suction-applying means including a suction-applying slot extending parallel to the axis of the cylinder and at a position just contiguous to the internal surface of the cylinder.

1 3. A yarn handling device according to claim 13, wherein the suction applying means includes a second slot over which the foraminous surface passes after the first mentioned slot, and wherein there are means for applying attenuated suction to the surface as it passes between the first-mentioned and second slots.

14. A yarn handling device according to claim 13, wherein the yarn-storage surface has a generally planar configuration and is on a foraminous member, with the suction-applying means disclosed behind the yarn-storage surface and arranged such that the yarn-storage surface moves relative to the suctionapplying means.

1 5. A yarn handling device according to claim 14, wherein said planar yarn-storage surface is on a straight run of a continuously moving foraminous conveyor belt.

16. A yarn handling device according to claim 9 or 10, and substantially as hereinbefore described.

1 7. A yarn handling device substantially as hereinbefore described with reference to, and as illustrated in the accompanying drawings.

1 8. A yarn handling process substantially as hereinbefore described with reference to the accompanying drawings.

19. Yarn which has been stored and taken up by the process of any one of claims 1 to 8 and 18.