GB2080847A - Unspun yarn - Google Patents

Abstract

An unspun yarn consists of a fibre assembly of substantially untwisted and parallel fibres 2 partially enclosed by a stitched cover 5, without relative twist between cover and fibre assembly. The cover consists of one or more threads stitched around the fibre assembly and provides constraint and support for the fibre assembly in a direction parallel to the fibre length and at spaced intervals in a direction at an angle to the fibre length. <IMAGE>

Description

SPECIFICATION Unspun yarn The present invention relates to an unspun yarn and to a method of making such a yarn.

The yarn of the present invention may be made from natural or man-made fibres or blends of such fibres.

The majority of yarns produced at present are spun with real twist. In one method of manufacture, spun yarns are produced by firstly straightening and untangling fibres by a carding-type process, to produce a flat web of fibres which is then divided across its width into narrow ribbons which are passed between rubbing aprons to consolidate the fibres into a rounded and continuous structure. This consolidated, continuous, structure is then twisted, drawn, and spun e.g. by a ring spinning or similar process, to form a spun yarn. The spinning process greatly increases the friction (and hence the cohesion) between the fibres, and a spun yarn is relatively strong in tension, whereas the unspun fibre structure will pull apart easily under tensile stress.However, since in a spun yarn the fibres are twisted together and consolidated, they form a relatively lean (i.e. thin and hard) structure, as opposed to the bulky (i.e. full and soft) structure of the unspun fibres. Lightness of weight and softness of 'feel' are highly prized in woolen garments, and a bulky structure in general provides better heat insulation than a lean structure, so than an unspun yarn has marked advantages if only it is possible to hold the fibres together in a manner which gives the yarn an acceptable tensile strength.

Unspun yarns are known in which the fibres have been further consolidated by additional rubbing to such a degree that the resulting yarn has sufficient tensile strength to permit hand-knitting. However, this type of unspun yarn is very difficult to machine knit and even in hand-knitting requires very gentle handling.

Garments knitted from this type of yarn tend to stretch and sag badly in use, due to poor cohesion between the fibres.

Also known are yarns with a core of false twisted or loosely twisted or untwisted fibres and a wrapping of threads or fibres wound helically around the outside of the core. This type of yarn structure is disclosed in U.S.

Patents Nos. 3079746, 3367095, 4003194, U.k. Patents 466940 and 436151, and German Patents Nos.

1685881, 2942131 and 497776.

German Patent 1963765 and U.S. Patent 3458987 disclose a variation of this type of yarn structure, in which the wrapping is formed from threads helically wound in opposite directions around the core, and the wrapping threads are melted or glued so that they adhere to each other at their cross-over points.

German Patent 3002952 and U.S. Patent 3732684 disclose a further variation of this type of yarn structure, in which the wrapping, although of helically wound threads, is discontinuous and irregular to give a non-uniform surface finish to the yarn.

All these helically-wrapped yarn structures have drawbacks, the most important being that the machinery needed to manufacture these yarns is both relatively expensive and has a low production rate. Secondly, there is a relative twist between the core and the wrapping, so that the wrapping tends to untwist if the yarn is cut or snagged.

The variation disclosed in German Patent 1963765 and U.S. Patent 3458987 partly overcomes this second drawback, but only by using a very complex and expensive manufacturing process and producing a stiffer, less flexible product.

A third drawback is that the relative twist between core and wrapping tends to compact and consolidate the core, giving a relatively lean yarn.

U.S. Patent 3857230 discloses a yarnlike product made of a bundle of generally parallel, untwisted fibres held together by a series of spaced polymer rings each of which passes around the fibre bundle, locally compacting and compressing the bundle, so that the product consists of a series of bulky, unrestrained fibre bundles separated by the compressed areas formed by said rings. The polymer rings are not linked together, so that if the ring spacing is greater than the average fibre length, the tensile strength of the final product is dependent upon the cohesion of the fibres; and if the ring spacing is less than the average fibre length, upon the strength of the bonds between the rings and the fibres.

German Patent 2817064 discloses a fancy or decorative yarn consisting of a spun 'effect' yarn which is formed into regular or irregular zig-zag patterns which are held in place by a 'core' yarn which is chain-stitched in a straight line across the pattern. In this yarn, the core yarn does not support the effect yarn over the whole length of the effect yarn, but simply secures the pattern in position. In other words, the effect yarn must be sufficiently cohesive to be self-supporting, because it is not constrained or supported by the core yarn over the major part of its length.

An object of the present invention is the provision of an unspun yarn which retains its bulky structure and soft 'feel' but which may be handled and used in the same manner, or substantially the same manner, as a conventional spun yarn. A further object of the present invention is to provide a method of making such an unspun yarn which does not require the use of complex or expensive machinery.

The present invention provides an unspun yarn comprising a fibre assembly of substan tially untwisted and parallel fibres, and a cover made of stitching, said cover partially enclosing said fibre assembly without relative twist between said cover and said fibre assembly; said cover comprising one or more threads stitched around the fibre assembly so as to provide constraint and support for the fibre assembly both in a direction parallel to the length of said fibres and at spaced intervals in a direction at an angle to the length of said fibres.

Peferably, the constraint and support provided by the cover in a direction at an angle to the fibre length is provided by a series of spaced bands each of which encircles the fibre assembly. Each band may comprise two or more band segments, each segment encircling part of the fibre assembly such that said segments in combination completely encircle the fibre assembly.

The fibres of the fibre assembly may be pure or blended natural or synthetic fibres.

The 'substantially untwisted' fibres may be completely untwisted or they may have a slight degree of twist or false twist, sufficient to permit the fibre assembly to be handled easily'up to the stage of applying the cover, but not sufficient to significantly reduce the bulk of the fibre assembly. For example, the known prior-art unwrapped unspun yarn discussed above, could be used as the fibre assembly of the present invention, as could the slubbings or rovings formed in the preparatory stages of conventional spinning processes. Rovings have about one-half turn of twist per inch; slubbings have less twist than rovings. Preferably, however, the fibre assembly is completely untwisted e.g. the slivers or tops formed in the early stages of conventional spinning processes.The constraint and support provided by the cover in a direction parallel to the length of the fibres may be provided by thread portions extending parellel to the length of the fibres but may be provided by thread portions extending in other directions.

As used herein, the term 'thread' includes conventional threads and spun yarns and also monofilament threads. The or each thread may be single or multiple strands.

The present invention further provides a method of making an unspun yarn comprising the steps of: providing a fibre assembly of substantially untwisted and parallel fibres; feeding said fibre assembly through a stitchforming machine to stitch one or more threads in an interlocking stitch around said fibre assembly to form a cover which partially encloses said fibre assembly without relative twist between said cover and said fibre assembly; said cover providing constraint and support for the fibre assembly both in a direction parallel to the length of said fibres and at spaced intervals in a direction at an angle to the length of said fibres.

As used herein, the term 'stitch-forming machine' includes overlocking machines, blind-stitching machines, hosiery seamer machines, and similar machines.

By way of example only, a preferred embodiment of the present invention is described in detail, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a fibre assembly before the cover is applied; Figure 2 is a view of one side of the fibre assembly of Fig. 1 with the thread cover applied; Figures 3 and 4 are diagrammatic representations of the thread arrangements in a cover formed from a 2-thread stitch and a 3-thread stitch respectively: and Figure 5 is a flow-diagram showing the principal stages of the method of the present invention.

Examples of suitable stitches for forming the cover are Union Special stitches types 101 (one-thread chain stitch), 502, (a 2thread overedge stitch), and 504 (a 3-thread overedge stitch). The Union Special stitch type numbers are as given in the Union Special Corporation Machine Reference 1981.

Stitch type 502 is illustrated in Figs. 2 and 3.

Referring to Figs. 1-3, a fibre assembly 2 comprises a strip of substantially straight, parallel fibres. The fibre assembly 2 is formed into an unspun yarn by encasing the fibre assembly in a cover 3 made of stitched threads 4 s 5 (see Figs. 2 and 3). The cover 3 is formed around the fibre assembly 2 by feeding the fibre assembly 2 through an overlocking machine which is set-up to stitch a 2thread overlock stitch. This stitch is formed from one thread 4 which extends along one side of the fibre assembly and also forms half 6a of each of a series of spaced bands 6 which encircle the fibre assembly at intervals along its length. The other thread 5 extends along the opposite side of the fibre assembly 2, and forms the other half 6b of each band 6.

Union Special stitch type 504 is shown in Fig. 4:- this stitch is formed from three threads 7, 8, 9, each of which provides a series of band segments 7a, 8a, 9a, respectively encircling approximately one-third of the fibre assembly 2, and also provides portions 7b, 8b, 9b, which extend parallel to the length of the fibres in the fibre assembly and provide three spaced longitudinal linking elements. The combination of each set of band segments 7a, 8a, 9a, completely encircles the fibre assembly.

For clarity in Figs. 2, 3, and 4, the threads 4 and 5 (Figs. 2 s 3) and 7, 8, 9, (Fig. 4) are shown as having different thicknesses, but in fact the threads may be of the same or different thicknesses. The threads may contrast in colour with the fibre assembly or may be of the same colour or may be of a fine monofilament thread which is semi-transparent and provides a cover which is almost invisible.

The type of stitch used to form the cover must be an interlocking stitch and must provide a series of bands spaced along the length of the fibre assembly, each band encircling the fibre assembly, and at least one element linking the bands together along the length of the fibre assembly. Each band need not be formed as a single unbroken band:-- instead, as shown in the preferred embodiments, each band may be formed from the combination of two or more band segments, each of which encircles part of the fibre assembly. The band segments forming each band may be aligned end-to-end around the fibre assembly or may be staggered along the length of the fibre assembly so that the segments are spaced apart along the length of the fibre assembly.

Each band may be perpendicular to the lengths of the fibres in the fibre assembly, but need not be:- a band at an angle greater or less than 90 to said fibre length is quite satisfactory. Each band and each linking element may be formed from single or multiple strands. The bands constrain and support the fibre assembly in a generally transverse direction, without greatly compressing or compacting the fibre assembly, and the linking element(s) prevent the fibres being pulled apart under tensile stress. Indeed, since the fibre assembly itself has very low tensile strength, the strength of the linking element(s) forms a major part of the tensile strength of the finished yarn.However, the fibre assembly may be further strengthened by the addition of one or more reinforcing threads which are fed into the stitch-forming machine parallel to the fibres of the fibre assembly, and covered with the stitched cover simultaneously with the fibre assembly. The reinforcing threads may be different colour to the fibre assembly, so that they also are ornamental.

Referring now to Fig. 5, one suitable layout of equipment for performing the present invention comprises a guide trough 10, four spaced pairs of driven pressure rollers, 11-14, a false-twisting unit 15, a modified over-locker type machine 16, thread spools 17, and a fifth pair of driven pressure rollers 1 8. The first four pairs of pressure rollers are the type normally used in fibre drafting or drawing units, but are run at a much higher speed than in such units (e.g. 2 meters/sec.

feed). The upper roller of each pair of pressure rollers 11, 12, 14, 15, is rubber faced to increase the frictional grip of the roller on the fibre assembly. The third pair of rollers 1 3 has a pressure band 1 9 driven by each roller.

Guide troughs 20 are positioned between roller pairs 11 and 12 and 1 2 and 13, to guide and support the fibre assembly during its travel between the rollers. For the same purpose, guide rings 21 are positioned be tween roller pairs 1 3 and 14, between the false twisting unit 1 5 and the overlocker 1 6, and between the last pair of rollers 1 8 and the yarn storage facilities (not shown).

In use, fibre assembly to be made into the yarn of the present invention is fed through the first four pairs of rollers 11-14 and is drawn out by said rollers:-- between the first and second pairs of rollers 11 and 12, the thickness of the fibre assembly is reduced to one-half of the initial thickness of the fibre assembly, and between the second and fourth pairs of rollers 1 2 and 14 the thickness is reduced to one-twentyfifth of the initial thick ness. The amount of thickness reduction in the fibre assembly may be adjusted by alter ing the relative speeds of the pressure rollers, in known manner.

In an ornamental thread and/or reinforcing thread(s) are to be added to the fibre assem bly, these are added between the third and fourth pairs of rollers 13, 14.

The false-twisting unit 1 5 is not essential, but is preferred if a reinforcing thread is not added to the fibre assembly, to strengthen the fibre assembly temporaily, before it passes through the overlocker 16.

The overlocker 1 6 is a standard commercial overlocking machine, modified by the removal of the pressure foot and of the tension appa ratus: instead of the machine itself being equipped to feed the fibre assembly through it, the fibre assembly is pulled through the overlocker by the tension of the last pairs of rollers 1 8. As the fibre assembly is pulled through the overlocker, thread is stitched around the fibre assembly by the overlocker, which forms interlocking stitches in known manner. Thread for stitching the cover around the fibre assembly is supplied from three spools 1 7 (for a 3-thread stitch).

The fibre assembly emerges from the over locker 1 6 as a strong, encased, yarn and after leaving the final rollers 1 8 is spooled or otherwise stored.

The finished yarn may be used for any purpose for which conventional spun yarn may be used. Normally, the cover remains on the fibre assembly for the life of the yarn.

however, it would be possible to make the cover threads of a material which is soluble in a solvent which does not damage the fibre assembly or which may be removed from the fibre assembly by other means (e.g. heating).

In this case, the unspun yarn of the present invention could be made up into the desired form (e.g. knitted into a garment) and then the cover threads removed to leave an article consisting only of the fibre assembly.

Claims (32)

1. An unspun yarn comprising a fibre as sembly of substantially untwisted and parallel fibres, and a cover made of stitching, said cover partially enclosing said fibre assembly without relative twist between said cover and said fibre assembly; said cover comprising one or more threads stitched around the fibre assembly in an interlocking stitch so as to provide constraint and support for the fibre assembly both in a direction parallel to the length of said fibres and at spaced intervals in a direction at an angle to the length of said fibres.

2. The unspun yarn as claimed in Claim 1 wherein said constraint and support provided by the cover in a direction parallel to the length of the fibres is provided by thread portions extending substantially parallel to the length of said fibres.

3. The unspun yarn as claimed in Claim 1 or Claim 2 wherein said constraint and support provided by the cover in a direction at an angle to the length of the fibres is provided by a series of spaced bands each of which encircles the fibre assembly.

4. The unspun yarn as claimed in Claim 3 wherein each band comprises two or more band 'segments, each segment encircling part of thefibre assembly such that said segments in combination completely encircle the fibre assembly.

5. The unspun yarn as claimed in Claim 4 wherein said cover is made of two threads, and each thread provides: a series of spaced band segments each encircling half of the fibre assembly, and portions extending substantially parallel to the length of said fibres and linking said band segments of said series.

6. The unspun yarn as claimed in Claim 4 wherein said cover is made of three threads, and each thread provides: a series of spaced band segments each encircling one-third of the fibre assembly, and portions extending substantially parallel to the length of said fibres and linking said band segments of said series.

7. The unspun yarn as claimed in claim 1 or claim 2 wherein said cover is formed from one thread.

8. The unspun yarn as claimed in any one of the preceding claims wherein the or each thread forming the cover is a single strand of thread.

9. The unspun yarn as claimed in any one of claims 1-7 wherein the or each thread forming the cover is formed of multiple strands of thread.

10. The unspun yarn as claimed in any one of the preceding claims wherein the or each thread forming the cover is a monofilament.

11. The unspun yarn as claimed in any one of the preceding claims wherein the fibres of said fibre assembly are completely untwisted.

12. The unspun yarn as claimed in any one of claims 1-10 wherein the fibres of said fibre assembly have a slight false twist (as hereinbefore defined).

1 3. The unspun yarn as claimed in any one of claims 1-10 wherein the fibres of said fibre assembly have a slight true twist (as hereinbefore defined).

14. The unspun yarn as claimed in any one of the preceding claims further comprising one or more reinforcing threads extending parallel to the length of said fibres and encased in the cover with the fibre assembly.

1 5. The unspun yarn as claimed in any one of the preceding claims wherein the cover is coloured differently to the fibre assembly, for decorative effect.

16. A method of making an unspun yarn comprising the steps of: providing a fibre assembly of substantially untwisted and parallel fibres; feeding said fibre assembly through a stitch-forming machine to stitch one or more threads in an interlocking stitch around said fibre assembly to form a cover which partially encloses said fibre assembly without relative twist between said cover and said fibre assembly; said cover providing constraint and sup port for the fibre assembly both in a direction parallel to the length of said fibres and at spaced intervals in a direction at an angle to the length of said fibres.

17. The method as claimed in claim 16 wherein the fibre assembly is reduced in thickness before entering the stitch-forming machine.

18. The method as claimed in Claim 16 or Claim 1 7 wherein the fibre assembly is given a false twist before entering the stitch-forming machine.

1 9. The method as claimed in any one of Claims 16-18 wherein one or more reinforcing threads extending parallel to the length of the fibres in the fibre assembly is or are added to the fibre assembly before the fibre assembly enters the stitch-forming machine.

20. The method as claimed in any one of claims 16-19 wherein said stitch-forming machine is one of the following: an overlocking machine, a blind-stitching machine, a hosiery seamer machine.

21. The method as claimed in any one of claims 16-19 wherein said constraint and support provided by the cover in a direction parallel to the length of the fibres is provided by thread portions extending substantially parallel to the length of said fibres.

22. The method as claimed in any one of claims 16-19 and 21 wherein said constraint and support provided by the cover in a direction at an angle to the length of the fibres is provided by a series of spaced bands each of which encircles the fibre assembly.

23. The method as claimed in Claim 22 wherein each band comprises two or more band segments, each segment encircling part of the fibre assembly such that said segments in combination completely encircle the fibre assembly.

24. The method as claimed in any one of claims 16-19 wherein the cover is formed from one of the following Union Special stitches: type 101, type 502, type 504.

25. The method as claimed in any one of claims 16-24 wherein the or each thread is a monofilament.

26. The method as claimed in any one of claims 16-25 wherein the or each thread is a single strand of thread.

27. The method as claimed in any one of claims 16-25 wherein the or each thread is multiple strands of thread.

28. The method as claimed in any one of claims 16-27 wherein the fibres of said fibre assembly are completely untwisted.

29. The method as claimed in any one of claims 16-27 wherein the fibres of said fibre assembly have a slight false twist (as hereinbefore defined).

30. The method as claimed in any one of claims 16-27 wherein the fibres of said fibre assembly have a slight true twist (as hereinbefore defined).

31. An unspun yarn substantially as hereinbefore described with reference to and as shown in Figs. 1-3 or Fig. 4 of the accompanying drawings.

32. A method of making an unspun yarn substantially as hereinbefore described with reference to and as shown in Fig. 5 of the accompanying drawings.