AU5120893A

AU5120893A - High bulk, multi-component yarn

Info

Publication number: AU5120893A
Application number: AU51208/93A
Authority: AU
Inventors: Peter Hendrik Brorens; Owen Leslie Roger Hartshorn; James Lappage; Jack David Watt
Original assignee: Wool Research Organization of New Zealand Inc
Current assignee: Wool Research Organization of New Zealand Inc
Priority date: 1992-10-14
Filing date: 1993-10-14
Publication date: 1994-05-09
Anticipated expiration: 2013-10-14
Also published as: GB2286605B; JPH08504893A; CA2147005A1; AU682320B2; GB9507633D0; WO1994009195A1; GB2286605A; DE4395220T1

Description

HIGH BULK, MULTI-COMPONENT YARN The present invention relates to the manufacture of yarns, threads, twines and like materials. More particularly the invention relates to the manufacture of high bulk yarns made from staple fibre material combined with continuous filaments or pre-spun staple fibre yarns.

Our earlier patent entitled "Improvements to Yarn Spinning Processes" New Zealand Patent No. 232390, describes and claims a method of spinning high bulk yarns on a worsted or semi-worsted spinning frame and modifications to the spinning frame required to carry out the process method. The method involves manipulating the fibres immediately before the insertion of twist such that part of every fibre is embodied in the tightly twisted core of the yarn, whilst a second part of every fibre is spun around the core with a much reduced level of twist, relative to fibre extent, by overfeeding. Such a yarn, therefore, includes a core, spun with a normal level of twist relative to the count of that core, and a surrounding sheath of relatively loosely twisted fibre from which is derived the high bulk of the yarn. The method of manufacturing this yarn, however, has the disadvantage that very fine bulky yarns cannot be made.

In any spinning process there exists a lower practical limit upon the number of fibres required in the cross-section of the yarn for the spinning process to be continuously operable without a high frequency of end breaks. In the worsted spinning process the generally recognised minimum number of fibres in the yarn cross-section is an average of 45 fibres. In the above-mentioned method for spinning high bulk worsted yarns the stresses imposed on the yarn during spinning are carried primarily by the fibre twisted into the core, whilst the fibre twisted into the bulky sheath is incorporated too loosely to contribute to yarn strength. Thus an average of at least 45 fibres is necessary in the core of the yarn to ensure an adequate spinning performance, whilst fibre in the bulky sheath contributes to the total yarn count. In a yarn spun with 50% of the fibre constituting the core and 50% of the fibre constituting the bulky sheath, the total number of fibres in the yarn cross- section is at least an average of 90. In the example of a worsted yarn spun from 22μm fibres a conventional yarn could be spun to a linear density as fine as 22.5 tex, whereas a high bulk worsted yarn, spun according to the method disclosed in our New Zealand Patent No. 232390 could not be spun finer than 45 tex.

In another earlier WRONZ Patent entitled "Multi- Component Yarn", New Zealand Patent No. 225679, a method is disclosed of producing in one operation a yarn comprised of one strand of staple fibre twisted together with two continuous filaments or pre-spun strands. The main advantage of this method lies in its ability to spin much finer yarns with as few as 20 staple fibres or less in the yarn cross- section. In one example of a yarn spun by this method a yarn was spun having an average of 26 fibres of a 29 μ wool and two nylon continuous filaments of 4.2 tex each. The resultant count of the yarn was 30 tex whereas a yarn spun conventionally from this wool could not be spun finer than 39 tex.

This multi-component yarn has many advantageous properties and end uses, particularly as a weaving yarn, but it has one major disadvantage in that it lacks bulk and it is generally considered unsuitable for many applications in knitting. The bulk of such a yarn is typically in the range

3 of 6-8 cm /g, which is the volume occupied by one gram of yarn measured at a pressure of 10 grams per square centimetre.

An object of the present invention is to produce in one operation a high bulk, fine count staple yarn by combining the technologies disclosed in our earlier New Zealand Patent No. 225679 and New Zealand Patent No. 232390.

A second object of the invention is to provide a method of producing high bulk, fine count yarns comprising one strand of staple fibre twisted together with one or more continuous filament or pre-spun yarns in which one or more filament or pre-spun yarns can be incorporated into the yarn structure as a core or wrapping component or components, relative to the staple fibre component.

A further object of the invention is to produce a high bulk, fine count staple yarn in which at least a proportion of the staple fibres is overfed into the yarn structure at the point of twist insertion such that the overfed portion of staple fibre is caused to protrude in loops from the yarn surface to constitute a bulky sheath of fibre.

A further object of the invention is to provide a yarn structure in which one part of substantially every staple fibre is incorporated into the core of the yarn and a second part of substantially every staple fibre is overfed into the bulky yarn sheath, such that the bulky sheath and the core are mechanically interconnected.

A further object of the invention is to provide a yarn structure having a high initial modulus of extensibility such that the yarn bulk is stable to the tensile stresses normally imposed upon a yarn in further processing steps such as winding, weaving and knitting.

Yet a further object of the invention is to provide a yarn manufacturing process which overcomes the above mentioned disadvantages and is capable of producing fine yarns having a high bulk characteristic.

According to a broadest aspect of the invention there is provided a process for producing a yarn comprising staple fibres twisted together with one or more filament or pre-spun yarns on ring or other types of spinning frames or machines which utilise any form of closed-end, long draft system, to form a yarn structure, and in which a proportion of the staple fibre is overfed into the structure to provide a bulky sheath of fibres twisted around a central core consisting of the one or more filament or pre-spun yarns and a second proportion of the staple fibre. According to the present invention there is provided a process for producing a yarn comprising staple fibres twisted together with one or more filament or pre-spun yarns on ring or other types of spinning frames or machines, and in which a proportion of the staple fibre is overfed into the structure to provide a bulky sheath of fibre twisted around a central core consisting of the one or more filament or pre-spun yarns and a second proportion of the staple fibre, the process including the steps of: mounting in association with a spinning machine one or more packages of single filament, multi-filament yarn or pre-spun yarn and a driven roller means adapted to control the feed of staple fibres between the front rollers of a drafting system and a point at which twist is first inserted between the fibres and filament or pre-spun yarn; dimensioning the roller means relative to the length of the staple fibres and its surface speed relative to the delivery speed of the front drafting rollers so that part of each staple fibre is overfed into the staple fibre strand forming the yarn; feeding one of the filament or pre-spun yarns to join with the drafted staple fibre strand at the nip of the front drafting rollers of the spinning machine and feeding one filament or pre-spun yarn to join with the staple fibre strand and the first filament or pre-spun yarn at any point between the nip of the front drafting rollers and downstream of the nip of the driven roller means, or; feeding one filament or pre-spun yarn to join with the stable fibre strand at a point downstream of the point of twist insertion.

According to a second aspect of the present invention there is provided apparatus for producing yarn according to the first aspect as hereinbefore described.

The package or packages of filament yarn can be silk, or any other natural, man-made or synthetic filament. Any type of pre-spun yarn may be used such as cotton or any other natural, man-made or synthetic fibre yarn.

Further aspects of the invention will become apparent from the following descriptions which are given by way of example only.

Examples of the present invention will now be described with reference to the accompanying diagrams in which:

Figure 1 shows in cross-section the basic elements of a type of ring spinning machine including a design of apparatus according to the present invention;

Figure 2 shows in plan the basic elements of a type of ring spinning machine including a design of apparatus according to the present invention;

Figure 3 shows in plan the basic elements of a type of hollow spindle spinning machine including a design of apparatus according to the present invention; Figure 4 shows in detail the yarn structure and the paths occupied by a typical staple fibre and the two filament or pre-spun yarns within the structure of a yarn spun on a ringframe spinning machine; and

Figure 5 shows in detail the yarn structure and the paths occupied by a typical staple fibre and the two filament or pre-spun yarns within the structure of a yarn spun on a hollow spindle spinning machine.

Referring now to Figure 1 a roving of staple fibre 1 is delivered through a pair of back drafting rollers 2, and a pair of apron rollers 3 and a pair of front drafting rollers 4 to emerge as a twistless strand fed over driven rollers 5 below which the yarn 7 is formed by the insertion of twist and which passes on through a pig-tail guide 8 onto a package 9 mounted on a spindle 10, via a ring and traveller mechanism 11. A first filament or pre-spun yarn 12 is fed in conjunction with the roving 1 at low tension into the nip of the front drafting rollers 4. A second filament or pre-spun yarn 13 may also be fed at low tension into the nip of rollers 4 but in spatial separation from the first filament or pre-spun yarn 12 and the roving 1. Alternatively the second filament or pre-spun yarn may be fed at low tension into the nip of the driven rollers 5, in spatial separation from the first filament or pre-spun yarn 12 and roving 1, or alternatively of the downstream rollers 5, these alternatives being shown in broken lines. In operation the spindle 10 rotates to insert twist into the yarn structure 7 and to wind a formed yarn onto the package 9 by co-operation with the ring and traveller mechanism 11. The twist inserted propagates upstream in the yarn as far as the nip of the driven rollers 5. The first filament or pre-spun yarn 12 is fed in contact with, or very close to, the roving 1 at the nip of rollers 4 and assists in carrying the twistless strand of staple fibres across the gap between the nips of rollers 4 and rollers 5 while becoming twisted into the core of the yarn 7. Referring now to Figure 2, the second filament or pre-spun yarn 12 when fed into the nip of rollers 4 is held in spatial separation from the first filament or pre-spun yarn 12 and its associated roving 1. Spatial separation is maintained until downstream of the nip of rollers 5 until it combines with the first filament or pre-spun yarn 12 and the strand of staple fibres 1 by becoming wrapped around that structure to form the yarn 7.

The driven rollers 5 are driven with a surface speed in excess of that of rollers 4 by a proportion in excess of unity, chosen according to the particular properties required in the finished yarn 7. The rollers 5 are loaded to provide a pressure at their nip which is sufficient to influence staple fibres after the trailing ends of those fibres have been released by the nip of rollers 4 during their passage through the system, but light enough to allow staple fibres still nipped by rollers 4 and the filament or pre-spun yarns to slip in the nips of rollers 5 without becoming excessively stretched or broken. Once the trailing end of a staple fibre has been released from the nip of rollers 4 that fibre becomes subject to the influence of rollers 5 only and is fed forwards by and at the surface speed of rollers 5 to become overfed into the yarn 7. The portion of a staple fibre fed into the yarn 7 downstream of the nip of rollers 5 before its trailing end is released by rollers 4 migrates by virtue of tension in the spinning yarn 7 towards the core of that yarn. The portion of a staple fibre overfed by rollers 5 is caused to wrap loosely around the core of yarn 7 by virtue of the overfeed and contributes to the bulky sheath.

The second filament or pre-spun yarn 13 may be fed into the system at one of any of the three alternative position 13 shown in Figures 1 and 2, and it is always kept in spatial separation from the first filament 12 and the staple fibre strand 1 until a point is reached downstream of the nip of rollers 5. When fed into the nip of rollers 4 the second filament or pre-spun yarn 13 is controlled at the surface speed of rollers 4 to be fed into the yarn 7 under the spinning tension of the yarn 7 to become wrapped relatively tightly around the core of the yarn 7. When fed into the nip of rollers 5 the filament or pre-spun yarn 13 is controlled at the surface speed of rollers 5 to become overfed into the yarn 7 and so becomes loosely wrapped around the core of yarn 7, contributing to the bulky sheath. When the filament or pre-spun yarn 13 is fed at low tension into the yarn 7 downstream of the nip of rollers 5 it is caused to wrap around the core of yarn 7 under low tension but does not contribute significantly to the bulky sheath. The choice of position at which the second filament or pre-spun yarn 13 is fed into the system is determined by the properties required in the finished yarn 7.

In another alternative the yarn 7 may be spun by including one only of the two filament or pre-spun yarns 12 and 13, either as a core or a wrapping component. When yarn is spun including only the filament or pre-spun yarn 12 as a core component the filament or pre-spun yarn can assist in carrying the staple fibre component from the nip of the front drafting rollers 4 through the nip of rollers 5 and on into the twisted yarn structure, and further contribute to the tensile strength of the yarn 7. When yarn is spun including only the filament or pre-spun yarn 13, fed at any of the alternative positions shown in Figure 1, the filament or pre- spun yarn 13 is caused to wrap around the yarn 7, assisting in binding the staple fibres within the yarn structure and contributing to the tensile strength of the yarn 7.

Referring now to Figure 3 a roving of staple fibres 1 is processed through a drafting system as described previously to be delivered via front drafting rollers 4, a pair of delivery rollers 17 to be wound into a package 18 driven by a scroll roller 19. The hollow spindle 14 has at its lower end mechanism 16 designed to grip the yarn with low force sufficient to rotate the yarn, inserting false twist upstream to the nip of rollers 5, but light enough to allow the yarn 7 to be drawn through the mechanism 16 by the delivery rollers 17 without significantly stretching or breaking the yarn 7.

Mounted on spindle 14 is a package 15 of a second filament or pre-spun yarn 13 which rotates with spindle 14. The filament or pre-spun yarn 13 combines with the forming yarn 7 by wrapping around yarn 7 under the tension of the balloon formed in the filament or pre-spun yarn 13. Downstream of the yarn gripping mechanism 16 there is substantially no twist between the staple fibres in yarn 7, but there is twist between the filament or pre-spun yarn 13 and the yarn 7 by virtue of the former wrapping around the latter.

The driven rollers 5 are driven at a surface speed greater than that of the front drafting rollers 4 to overfeed the trailing portions of staple fibres into the yarn 7 as previously described. A first filament or pre-spun yarn 12 is fed at the nip of rollers 4, also as previously described, to become incorporated into the core of yarn 7 and assist in carrying the staple fibres from the nip of rollers 4 to the point at which the structure is wrapped by the filament or pre-spun yarn 13.

Alternatively yarn may also be spun as hereinbefore described on a hollow spindle machine, but including only one or either of the two filament or pre-spun yarns 12 and 13.

Referring now to Figure 4 there is illustrated the path in the yarn structure of a typical staple fibre 20 showing the leading end of the fibre firmly twisted into the yarn core with its trailing end loosely twisted into a sheath around the core in a yarn produced according to a first aspect of the invention including two filament or pre-spun yarns 12 and 13. The trailing end is then twisted into the yarn with a lower twist per unit fibre length. The first filament or pre-spun yarn 12 is shown, as a full line, embedded within the core of the yarn structure, and the second filament or pre-spun yarn 13 is shown wrapping the structure, for yarns spun as hereinbefore described on a ringframe. The twist angle of fibres lying on the surface of the yarn is the same twist angle as that of the second filament or pre-spun yarn 13.

Referring now to Figure 5 there is illustrated the path in the yarn structure of a typical staple fibre 21 showing the leading end of the fibre firmly embedded in the yarn core with its trailing end bulging in loops from the yarn surface in a yarn produced on a hollow spindle spinning machine according to a first aspect of the invention including two filament or pre-spun yarns 12 and 13. The first filament or pre-spun yarn 12 is shown in a full line embedded within the core of the yarn, and the second filament or pre-spun yarn 13 is shown wrapping the structure. In this yarn structure there is no twist between the staple fibres themselves or between the staple fibres and the first filament or pre-spun yarn 12; these lie in substantially parallel relationship within the core of the yarn. Twist exists between the whole of this structure and the second filament or pre-spun yarn 13 by virtue of the second filament or pre-spun yarn being wrapped around the structure. The trailing ends of the staple fibres overfed into the yarn structure are also bound to the yarn structure by the wrapping filament or pre-spun yarn 13 forming loops of fibre protruding from the yarn surface between wrapping points. In this yarn structure the protruding fibre loops are very stable, being securely anchored by the wrapping component 13, and contribute to the bulky sheath surrounding the yarn core.

In one example of yarn spun on a worsted ringframe by the method described in WRONZ New Zealand Patent specification No. 225679 a 28 μm blend of wool was drafted to a strand of linear density of 18.5 tex and twisted together with two filament yarns of linear density 2.2 tex each, with 680 tpm, to achieve a finished yarn linear density of 22.9 tex, and having an average of 23 staple fibres in the yarn cross-section. The bulk of this yarn was measured, after fully relaxing by steaming a hank of the yarn in an autoclave for 2 minutes at 100°C, and found to be 7.47cm /g. The same yarn structure was then spun by the method described in WRONZ New Zealand Patent No. 225679 but with the addition of the driven roller means described in WRONZ New Zealand Patent No. 232390 to generate yarn bulk, all with 825 tpm twist. In this example the driven roller means (5 in Figure 1) was driven at a surface speed 70% greater than that of the front drafting rollers (4 in Figure 1) . The bulk of this yarn was measured, after fully relaxing a hank of the yarn by steaming in an autoclave for 2 minutes at 100°C, and found to be

₃ 11.20cm /g.

In a second example the same 28 μ wool used for the first example was spun on a hollow spindle machine to a linear density of 22.0 tex which included two filament yarns of 2.2 tex each and a strand of staple fibre of linear density 17.6 tex and having 22 staple fibres in the cross- section. One yarn was spun with 430 tpm twist and without the use of driven rollers 5. After fully relaxing the yarn by steaming a hank of the yarn in an autoclave for 2 minutes at 100°C the bulk was measured and found to be 24.4 cm /g. A similar yarn structure was then spun using also the driven rollers 5 and after fully relaxing a hank of the yarn in an autoclave for 2 minutes at 100°C the bulk was measured and

3 found to be 27.7 cm /g. In this example the driven roller 5 was driven at a surface speed 57% greater than that of the front drafting rollers 4.

Thus by this invention there is provided a yarn manufacturing process capable of producing fine yarns having a high bulk characteristic, comprising staple fibre and filament or pre-spun yarns. The staple fibre component can comprise as few as 20 fibres or fewer in the cross-section of the yarn under commercially viable conditions.

Particular examples of the invention have been described and it is envisaged that improvements and modifications can be made without departing from the scope of the invention.

Claims

1. A method of producing high bulk, fine count yarns comprising one strand of staple fibre twisted together with one or more continuous filament or pre-spun yarns in which one or more filament or pre-spun yarns can be incorporated into the yarn structure as a core or wrapping component or components, relative to the staple fibre component.

2. A method of producing high bulk, fine count yarns substantially as hereinbefore described with reference to the accompanying drawings.

3. A high bulk, fine count staple yarn in which at least a proportion of the staple fibres is overfed into the yarn structure at the point of twist insertion such that the overfed portion of staple fibre is caused to protrude in loops from the yarn surface to constitute a bulky sheath of fibre.

4. A yarn as claimed in claim 3 in which one part of substantially every staple fibre is incorporated into the core of the yarn and a second part of substantially every staple fibre is overfed into the bulky yarn sheath, such that the bulky sheath and the core are mechanically interconnected.

5. A yarn as claimed in claim 3 or claim 4 having a high initial modulus of extensibility such that the bulky sheath is stable to the tensile stresses normally imposed upon a yarn in further processing steps such as winding, weaving and knitting.

6. A process for producing a yarn comprising staple fibres twisted together with one or more filament or pre-spun yarns on ring or other types of spinning frames or machines to form a yarn structure in which a proportion of the staple fibre is overfed into the structure to provide a bulky sheath of fibres twisted around a central core consisting of the one or more filament or pre-spun yarns and a second proportion of the staple fibre.

7. A process for producing a yarn comprising staple fibres twisted together with one or more filament or pre-spun yarns on ring or other types of spinning frames or machines, and in which a proportion of the staple fibre is overfed into the structure to provide a bulky sheath of fibre twisted around a central core consisting of the one or more filament or pre- spun yarns and a second proportion of the staple fibre, the process including the steps of: mounting in association with a spinning machine one or more packages of single filament, multi-filament yarn or pre-spun yarn and a driven roller means adapted to control the feed of staple fibres between the front rollers of a drafting system and a point at which twist is first inserted between the fibres and filament or pre-spun yarn; dimensioning the roller means relative to the length of the staple fibres and its surface speed relative to the delivery speed of the front drafting rollers so that part of each staple fibre is overfed into the staple fibre strand forming the yarn; feeding one of the filament or pre-spun yarns to join with the drafted staple fibre strand at the nip of the front drafting rollers of the spinning machine and feeding one filament or pre-spun yarn to join with the staple fibre strand and the first filament or pre-spun yarn at any point between the nip of the front drafting rollers and downstream of the nip of the driven roller means, or; feeding one filament or pre-spun yarn to join with the staple fibre strand at a point downstream of the point of twist insertion.

8. A process as claimed in claim 7 wherein the package or packages of filament yarn are silk, or any other natural, man-made or synthetic filament.

9. A process as claimed in claim 7 or claim 8 wherein any type of pre-spun yarn is be used such as cotton or any other natural, man-made or synthetic fibre yarn.

10. An apparatus for producing yarn as claimed in claim 3 using a ring or other spinning frame or machine with a pair of back drafting rollers, a pair of apron rollers and a pair of front drafting rollers or any other closed-end long drafting system arranged so that the roving of staple fibre is delivered to the rollers and emerges as a twistless strand fed over driven rollers below which the yarn is formed via a ring and traveller mechanism by the insertion of twist as it passes through a pig-tail guide onto a package mounted on a spindle.

11. An apparatus as claimed in claim 10 wherein a first filament or pre-spun yarn is fed in conjunction with the roving at low tension into the nip of the front drafting rollers, a second filament or pre-spun yarn can also be fed at low tension into the nip of rollers but in spatial separation from the first filament or pre-spun yarn and the roving.

12. An apparatus as claimed in claim 11 wherein alternatively the second filament or pre-spun yarn is fed at low tension into the nip of the driven rollers, in spatial separation from the first filament or pre-spun yarn and roving, or alternatively of the downstream rollers.

13. An apparatus as claimed in claim 12 wherein the driven rollers are driven with a surface speed in excess of that of the front drafting rollers by a proportion in excess of unity, chosen according to the particular properties required in the finished yarn so that the portion of a staple fibre overfed by rollers is caused to wrap loosely around the core of yarn by virtue of the overfeed and thus contributes to the bulky sheath.

14. An apparatus for producing yarn as hereinbefore described with reference to the accompanying drawings.