WO1996016207A1

WO1996016207A1 - Improvements to the manufacture of yarn spun on closed-end, high draft spinning systems

Info

Publication number: WO1996016207A1
Application number: PCT/NZ1995/000122
Authority: WO
Inventors: Nigel Anthony Gull Johnson; James Lappage; Owen Leslie Roger Hartshorn; Jack David Watt
Original assignee: Wool Research Organization of New Zealand Inc
Current assignee: Wool Research Organization of New Zealand Inc
Priority date: 1994-11-24
Filing date: 1995-11-24
Publication date: 1996-05-30
Anticipated expiration: 1997-05-24
Also published as: AU3940395A; JPH08158171A

Abstract

Improvements to the manufacture of yarn on spun on closed-end, high draft spinning systems are described. A yarn structure is formed in which each of the constituent fibres migrates between the surface and the core of the yarn so that part or parts of each fibre are trapped and bound by parts of other fibres in the yarn cross-section. The constituent fibres can migrate cyclically between the core and the surface of the yarn or the migration or withdrawal of individual fibres can be impeded by a degree of inter-fibre entanglement deliberately introduced in the yarn structure. Mechanisms for producing the yarn structure are also described, such mechanisms being driven by frictional contact with one (1) or other (2) of the front drafting rollers. Such mechanisms include overfeeding (6) via differential speed rollers and using an embossing delivery roller (4).

Description

IMPROVEMENTS TO THE MANUFACTURE OF YARN SPUN ON CLOSED-END, HIGH DRAFT SPINNING SYSTEMS

The invention relates to the manufacture of yarns from a well-aligned assembly of any type of staple fibre or fibre blend. More particularly it relates to improvements to the apparatus used to carry out a method of, spinning a singles yarn which is weavable directly as warp without the need of sizing or plying and which is disclosed in our earlier Patent Specification No. PCT/NZ 93/00055 the content of which is incorporated herein by reference.

Our earlier patent discloses a method of spinning a singles yam from a well-aligned sliver or roving, in which yarn fibres do not lie in parallel helical paths of constant radius, and in which none of the constituent fibres lie wholly on the yarn surface, but part, or parts of every fibre is bound within the yarn structure by part, or parts, of other fibres in the yarn. This yarn structure thus includes a degree of additional fibre migration and inter-fibre entanglement which enhances the performance of the yarn by inhibiting removal of individual fibres from the yarn structure. This yarn has proved to be capable of withstanding the stresses and abrasion imposed on warp yarns during the weaving process and in particular the abrasive actions of the reed, the heddles and co-adjacent warp threads.

A preferred method of achieving fibre migration and inter-fibre entanglement during the spinning process, disclosed in our earlier patent specification, is by overfeeding a drafted strand of fibres from the front drafting rollers, or delivery rollers, of a conventional high-draft drafting apparatus, to an additional pair of plain rollers immediately downstream of the front drafting rollers. The surface speed of the additional rollers is less than that of the front drafting rollers to effect the overfeed condition, and the difference in surface speed between the two pairs of rollers can be in range 0-30%. Figure 1 with said specification No. PCT/NZ93/00055 shows the approximate relative positions of the front drafting rollers 1 and 2 and the additional rollers 3 and 4 in cross-section, which also shows a possible path taken by the fibres (5) through a zone of overfeed between the two roller nips.

At least one of the additional rollers is driven positively in a precise speed relationship to the speed of the positively driven roller ( 1 ) of the front drafting rollers. Means of driving the additional rollers is not shown in our earlier patent specification, but it is accepted as obvious that the additional rollers can be constructed and mounted on a spinning machine in the same way as the existing drafting rollers, in which one roller usually forms a continuous shaft running the length of the spinning machine, this being the positively driven roller, whilst the second roller is usually formed as individual rollers, one at each spindle point on the spinning machine, and mounted in pairs on connecting shafts for convenient fixing in the drafting apparatus and convenient loading of the rollers at a necessary pressure. It is also accepted as obvious that the additional rollers can then be driven via a simple gear mechanism in the same way as the existing front drafting rollers are driven.

This design however, has the disadvantage that the continuous additional bottom roller can be difficult to locate and support by bearings on some spinning frames since preferred positioning can be obstructed by existing drafting roller support brackets, which may need to be modified, and the lack of existing suitable machined surfaces upon which to mount bearing supports for accurate alignment of the additional bottom roller (3). Different makes and models of spinning machines differ in these details such that modification according to the method described above utilising a continuous driven shaft may necessitate a one-off design for each separate installation.

It is also accepted as obvious that the additional rollers can be mounted on the spinning frame individually, or in groups of 2,4 or 6 so as not to interfere with the existing drafting roller support brackets, but this design then has the disadvantage that each group of additional rollers has to be driven separately, requiring a plurality of drive means over the whole spinning frame, with such drive means being susceptible to contamination by fly and other waste fibre unless it is adequately shielded.

A first object of the present invention is to provide a design of additional roller means which is completely free from interference with the drafting roller support brackets, does not rely upon the existence of accurately machined surfaces for precise placement, is driven by simple means not susceptible to contamination by fly or other waste fibre, and is more readily applicable to a variety of make and model of spinning machine without the need of extensive one-off design.

A second object of the present invention is to overcome the above described disadvantages by providing a method for splitting a strand of fibres into two or more subgroups, separating those subgroups spatially sufficient to allow the efficient generation of a degree of false twist separately in each subgroup, in a regular and controlled cyclic manner, without the possibility of randomly generated intermittent faults, to provide an abrasively strong yarn structure which is resistant to the stresses and forces applied to warp yarn during the weaving process. It is a further object of the present invention to provide a simple means for splitting a strand of fibres into two or more separate subgroups, comprising a single roller means mechanically held against and driven by one or other of the front drafting rollers of a spinning machine.

According to a first aspect of the invention there is provided a zone through which fibres must pass in a twistless state such that the fibre stream can be split into two or more separate subgroups.

According to a second aspect of the invention there is provided downstream of a nip of front drafting rollers of a spinning machine a roller which may cooperate with and be driven by, one of the front drafting rollers, and around an arc of which the strand, or subgroups, of fibres must pass such that the roller serves to confine yarn twist downstream.

According to a third aspect of the invention there is provided a zone through which the fibres must pass in a twistless state with at least a proportion of the fibres in a tensionless or overfeed condition such that part or parts of fibres entering that zone can be caused to deviate from a straight line path between front drafting rollers of the spinning machine and the point at which twist is inserted between the fibres.

According to a fourth aspect of the invention there is provided downstream of the front drafting rollers of a spinning machine an additional pair of rollers forming a nip immediately downstream of the front drafting rollers, which additional pair of rollers deliver at a speed slower than the speed of the front drafting rollers whilst the additional rollers serve also to confine yarn twist downstream.

TITUTE SHEET According to a fifth aspect of the invention there is provided means for spreading the fibres over a wide front upstream of the point at which twist is inserted between the fibres, one such means comprising an overfeed zone between the front drafting rollers and the twist insertion point.

According to a sixth aspect of the invention there is provided an additional pair of cooperating rollers which are readily and easily mounted immediately downstream of front drafting rollers on any spinning machine without the need of accurately machined surfaces or extensive design.

According to a seventh aspect of the invention there is provided a pair of cooperating additional rollers which can be driven by simple means, already existing on the spinning machine, at fixed speed relationship to the speed of the front drafting rollers.

According to an eighth aspect of the invention there is provided a yarn structure in which substantially every individual fibre is caused to migrate in a regular and controlled cyclic manner between the core and the surface of a yarn by virtue of the fibres being twisted together in two or more separate subgroups by false-twist and the subgroups being twisted together by overlying real twist in the yarn, and in which the subgroups of fibres are formed by splitting a single strand of fibre derived from a single end of roving or sliver.

Further aspects of the invention will become apparent from the following description.

SUBSTITUTE SHEET The present invention will now be described with reference to the attached drawings in which:

Figure 1 depicts in cross-section a design of apparatus according to the invention disclosed in our earlier patent specification No PCT/NZ 93/00055;

Figure 2 depicts in cross-section a preferred design of apparatus according to the present invention comprising front drafting rollers of a spinning machine, an additional pair of rollers, a zone of overfeed between the two nips of those roller pairs, the path of fibres through that zone, part of the top loading arm of the drafting system, part of the machine chassis upon which the drafting system is mounted, means for driving the additional rollers in fixed speed relationship to the speed of the front drafting rollers, and one means for mounting the additional rollers on the spinning machine;

Figure 3 depicts in cross-section a design of apparatus according to the present invention showing alternative means for mounting and driving the additional rollers;

Figure 4 depicts in plan the additional rollers and one of the front drafting rollers;

Figure 5 depicts in cross-section a pair of front drafting rollers of a spinning machine and an additional roller cooperating with and driven frictionally by one of the front drafting rollers, and the path of the yarn through the system of rollers;

T Figure 6 depicts in plan one design of embossed roller for splitting the twistless fibre strand into two or more separate subgroups, the path of fibres around an arc of that roller and the point at which twist is inserted into the yarn; and

Figure 7 depicts in plan an alternative design of embossed roller for splitting the twistless fibre strand into two or more separate subgroups, the path of fibres around an arc of that roller and the point at which twist is inserted into the yarn.

Referring now to Figure 2, the drafted strand 5 passes through the nip of the front drafting rollers 1 and 2, into a zone of overfeed 6 between the nips between rollers 1 and 2 and the additional rollers 3 and 4, through the nips of the additional rollers 3 and 4 and on via a pigtail guide (not shown) to the spindle (not shown). The top additional roller 4 is subtended by a bracket 7, which may be made of spring steel, from the top loading arm 8 of the drafting system. The roller 4 has one or more shoulders of slightly greater diameter than the main surface of roller 4 and positioned such that the shoulders contact the surface of the bottom front roller 1 such that roller 4 is driven by friction by roller 1. The bottom additional roller 3 is mounted on the chassis 1 1 of the spinning machine or may be mounted on the bracket 7. The roller 3 is dimensioned such that it contacts roller 4 only over the main surface of roller 4, avoiding contact with the shoulder(s). Roller 4 is loaded against both roller 1 and roller 3 by virtue of the spring steel bracket 7 which is dimensioned and positioned such that a force is exerted on the axle of the roller 4 directed in a plane approximately parallel to the plane containing the axis of roller 4 and the space between rollers 1 and 2. The magnitude of the loading force is not critical but is preferably of the order of 1 -2kg/cm of nip between the respective cooperating rollers. The spacing between the surface of the shoulders of roller 4 and the surface of roller 2 is not critical, but is preferable of the order of 1 -5mm. Similarly the spacing between the surfaces of rollers 1 and 3 is not critical, but is preferably of the order of 1 -5mm.

An alternative means for mounting and locating the recessed roller 4 is by magnetic force. Roller 4 may be substantially made from a suitable magnetic material, magnetised and held in position by magnetic force of attraction to both rollers 1 and 3, thus obviating the need of support bracket 7.

Roller 4 is driven by friction by the bottom front drafting roller 1 of the spinning machine, and to ensure positive precise driving of roller 4 its shoulders are preferably made from an elastomeric material such as the synthetic rubber compound normally used in the manufacture of drafting roller cots; alternatively the shoulder(s) may be one or more o-rings of elastomeric material, located in annular recesses in roller 4. The relieved surface of roller 4 may be made of an elastomeric material, metal or hard plastic. The surface of roller 3 may be made from an elastomeric material, metal or hard plastic to ensure positive and precise driving of roller 3 by frictional contact with the relieved portion of roller 4.

In operation the drafted strand 5 is delivered by the front drafting rollers 1 and 2, passes through the space between the surface of roller 1 and the relieved surface of roller 4, then through the nip between roller 3 and the relieved surface of roller 4 and on towards the spindle. The overfeed between the front drafting rollers 1 and 2 and the additional rollers 3 and 4 may be in the range 0-30%, depending upon the properties required in the

SUBSTITUTE SHEET yarn, and is determined by the ratio of the diameters of the relieved portion and the shoulder(s) of roller 4.

Referring now to Figure 3, the relieved roller 4 may be driven by frictional contact of its shoulders with the surface of the top drafting roller 2. Since roller 2 is normally covered with an elastomeric cot then the shoulders of roller 4 may be made from either a metal or an elastomer material. The plain additional roller 3 may be suspended by bracket 12 from the top loading arm 8 of the drafting system. The relieved additional roller 4 may be suspended from and loaded against rollers 2 and 3 by springs 13, and located in position by virtue of the recess 14 and the shoulders enclosing the roller 3. The operation of this embodiment of the invention is similar to that of the embodiment depicted in Figure 2.

Referring now to Figure 4, the relieved roller 4 is dimensioned such that the major portion of it is smaller in diameter than the two shoulders 15, and the drafting roller [1 or 2] is dimensioned such that it is at least as long as the outside length of relieved roller 4. The second additional roller 3 is dimensioned such that its full length is accommodated between the shoulders of roller 4 with a small clearance to preclude binding. Different relationships between the lengths of the rollers can apply if only one shoulder is used.

Referring now to Figure 5, the yarn 5 is delivered by front drafting rollers 1 and 2 and passes through a nip made between roller 2 and an additional roller 17 which the yarn also wraps in an arc. Twist is inserted into the yarn by a spindle (not shown) and propagates upstream as far as the point at which the yarn leaves the surface of roller 17 upstream of which the yarn is in the form of a twistless strand. Roller 1 7 cooperates with, and is frictionally driven by, roller 2.

Referring now to Figure 6, the additional roller 1 7 may be an embossed roller which includes a groove 1 8 which may split into two branches 1 9 and 20 around a central wedge-shaped portion 21 before recombining into a single groove. The groove, or relieved part of the roller, is shown in Figure 6 as a shaded area, and is dimensioned to accommodate the strand of fibres 5 in a layer one or more fibres deep. In operation, as the roller 1 7 rotates with its surface moving in the same direction as, and substantially at the delivery speed of, the yarn, the point of the central wedge-shaped portion 21 penetrates the strand within the zone of zero twist, splitting it into two components 22 and 23 each of which is forced by tension to track in the corresponding groove 1 9 or 20. The two strands 22 and 23 develop a degree of false twist by virtue of the torque due to twist in the fully formed yarn 5, a proportion of which becomes incorporated as strand twist within the structure of yarn 5. When the wedge-shaped area 21 passes out of the arc of contact between the yarn and roller 17, the strands 22 and 23 are released and recombined into a single strand within the groove 1 8. Again twist extant in each strand at the moment of rejoining the two strands will also become incorporated within the yarn structure. The process then repeats as the wedge-shaped portion 21 again approaches the twistless strand.

The embossed roller 1 7 may include one or more wedge-shaped elements 21 around its circumference, depending upon the circumference of roller 1 7 and the cycle-length of the false twisted zones of strand which is to be generated.

SUBSTITUTE SHEET Referring now to Figure 7, which depicts an alternative design of embossed roller 1 7 which includes a single helical groove 24. The groove 24 is dimensioned such that it can contain a proportion but not all of the fibres in the twistless strand. In operation roller 1 7 rotates with a surface speed substantially equal to the delivery speed of the strand 25. Fibres collecting in the groove 24 are forced by tension to track with the groove as a separate group 26 or 27. When roller 1 7 rotates to again present the groove to the strand 25 a further group of fibres is detached and tracked to one side. Tracking will continue until either the fibres comprising a subgroup run out, or the group is pulled out of the groove 24 by the increasing component of tension parallel to the roller axis. Again as the separate sub-groups of fibres 25, 26 and 27 form, false twist is generated in each and becomes incorporated into the structure of yarn 5.

The additional roller 17 may be made of hardened steel, or durable material, and may cooperate with and be driven by the elastomerically covered top drafting roller. Alternatively the additional roller 1 7 may cooperate with and be driven by the hardened steel bottom drafting roller.

Thus by this invention there is provided a variety of methods and apparatus for spinning a yarn from a well-aligned sliver or roving in which part or parts of all of the fibres are bound within the yarn structure by part or parts of other fibres in the yarn such that no fibres exist lying wholly on the surface of the yarn and the fibres do not lie in parallel helical relationships over a significant length within the yarn structure. Thus this yarn exhibits a significantly increased resistance to abrasion, loss of fibre or general breakdown of the yarn structure during further processing as yarn, or during use or service in end products. The yarn is also significantly less hairy than conventionally spun yarns with greatly increased resistance to yarn failure during weaving, and is economically weavable.

The yarn may be spun from a single end of sliver or roving, or by drafting two or more slivers or rovings together, side-by-side and_^ in close contact, to improve the yarn evenness through the effect known as doubling, or, through the rovings differing for example in colour or fibre type, to provide an effect yarn.

Particular examples of this invention have been described and it is envisaged that modifications and variations can take place without departing from the scope of the appended claims.

By this invention there is provided a design of apparatus for spinning yarn from well-aligned sliver or roving according to the invention disclosed in our earlier patent specification No PCT/NZ 93/00055, which does not interfere with existing drafting roller support brackets, does not depend upon the existence of accurately machined surfaces for locating and mounting components, is driven by simple means not susceptible to contamination by fly or waste fibre, and can readily be adapted to a variety of make and model of spinning machine without the need for extensive one-off design. This design is cheaper to manufacture and install than other more obvious designs, and is potentially more attractive to industry.

Claims

1 . A method of producing a yarn structure, using a closed-end, high draft spinning system, in which a normal parallel fibre geometry is disturbed by making fibres migrate cyclically or randomly between the core aryd the surface of the yarn, and/or fibres are made to become randomly inter- entangled in sub-groupings by twist, and from which migration or withdrawal of individual fibres is impeded by the said disturbed fibre geometry or random inter-fibre entanglement.

2. A method of producing a yarn structure, using a closed-end, high draft spinning system, which includes a zone through which fibres must pass in a twistless state such that the fibre stream can be split into two or more separate subgroups.

3. A method according to claim 2 wherein the zone through which the fibres must pass in a twistless state causes at least a proportion of the fibres in a tensionless or overfeed condition entering that the zone to deviate from a straight line path between front drafting rollers of the spinning machine and the point at which twist is inserted between the fibres.

4. A method according to claim 1 wherein a stream of fibres delivered by front rollers is made to split into two or more sub-groυpings separated in space and then to converge again into a single strand in a continuous and cyclic manner.

5. A method according to claim 4 wherein the sub-groupings of fibres are manipulated independently or may react independently under the influence of twist during formation of the yarn structure.

6. An apparatus for producing a yarn structure, using a closed-end, high draft spinning system with, downstream of a nip of front drafting rollers of the spinning machine, a roller which cooperates with and may be driven by, one of the front drafting rollers, and around an arc of which the strand, or subgroups, of fibres must pass such that the roller serves to confine yarn twist downstream.

7. An apparatus according to claim 6 comprising an embossed roller situated downstream of the nip of the delivery rollers and driven by frictional contact with either one of the delivery rollers, where the embossed roller includes grooves or recesses or projecting elements on its surface.

8. An apparatus according to claim 7 wherein the grooves, recesses or projecting elements are discontinuous around the periphery of the roller and include leading edges designed to penetrate and split a stream of substantially parallel and twistless fibres.

9. An apparatus according to either claim 7 or 8 wherein the grooves, recesses or projecting elements extend around a substantial portion of the roller surface.

10. An apparatus according to claims 7 to 9 in which the grooves, recesses or projecting elements are formed by cutting one or more helical threads in the embossed roller.

TE SHEET

1 1 . An apparatus according to any of claims 6 to 10 wherein the roller means are driven by frictional contact between one roller and one of the front drafting rollers.

12. An apparatus for producing a yarn structure, using a closed-end, high draft spinning system, with means for spreading the fibres over a wide front upstream of the point at which twist is inserted between the fibres, such means comprising an overfeed zone between the front drafting rollers and the twist insertion point.

13. An apparatus according to claim 12 wherein the overfeed zone is created by an additional pair of rollers which form a nip immediately downstream of the front drafting rollers, which additional pair of rollers deliver at a speed slower than the speed of the front drafting rollers whilst the additional rollers serve also to confine yarn twist downstream.

14. An apparatus according to claim 12 wherein the means consists of an additional pair of cooperating rollers which are readily and easily mounted immediately downstream of front drafting rollers on the spinning machine without the need of accurately machined surfaces or extensive design.

15. An apparatus according to either claim 13 or claim 14 wherein the pair of cooperating additional rollers are driven by simple means, already existing on the spinning machine, at fixed speed relationship to the speed of the front drafting rollers.

1 6. An apparatus for producing yarn according to claim 1 2 wherein the overfeed zone is created by a means for delivering the fibres at a speed slower than the delivery speed of front drafting rollers.

1 7. An apparatus according to claim 1 6 wherein the means is driven by frictional contact between one roller and one of the front drafting rollers.

1 8. An apparatus according to claim .1 7 wherein the surface speed at the nip of the roller means is determined by a recessed portion cut in the surface of the driven roller.

1 9. A yarn structure produced by any of the methods of claims 1 to 5.

20. A yarn structure produced by any of the apparatuses of claim 6 to 1 7.

21 . A yarn structure in which substantially every individual fibre is caused to migrate in a regular and controlled cyclic manner between the core and the surface of a yarn by virtue of the fibres being twisted together in two or more separate subgroups by false-twist and the subgroups being twisted together by overlying real twist in the yarn, and in which the subgroups of fibres are formed by splitting a single strand of fibre derived from a single end of roving or sliver.

E SHEET AMENDED CLAIMS

[received by the International Bureau on OS May 1996 (09.05.96) ; original claims 1 -21 replaced by amended claims 1 -11 (2 pages) ]

1. An apparatus for producing a yarn structure, using a closed-end, high draft spinning system with, downstream of a nip of front drafting rollers of the spinning machine, a roller which cooperates with and may be driven by, one of the front drafting rollers, and around an arc of which the strand, or subgroups, of fibres must pass such that the roller serves to confine yarn twist downstream-

2. An apparatus according to claim 1 comprising an embossed roller situated downstream of the nip of the delivery rollers and driven by frictional contact with either one of the delivery rollers, where the embossed roller includes grooves or recesses or projecting elements on its surface.

3. An apparatus according to claim 2 wherein the grooves, recesses or projecting elements are discontinuous around the periphery of the roller and include leading edges designed to penetrate and split a stream of substantially parallel and twistless fibres.

4. An apparatus according to either claim 2 or 3 wherein the grooves, recesses or projecting elements extend around a substantial portion of the roller surface.

5. An apparatus according to claims 2 to 4 in which the grooves, recesses or projecting elements are formed by cutting one or more helical threads in the embossed roller. 6. An apparatus according to any of claims 1 to 5 wherein the roller means is driven by frictional contact with one of the front drafting rollers.

7. An apparatus for producing a yarn structure, using a closed-end, high draft spinning system, with means for spreading the fibres over a wide front upstream of the point at which twist is inserted between the fibres, such means comprising an overfeed zone between the front drafting rollers and the twist insertion point, and an additional pair of cooperating rollers which are readily and easily mounted immediately downstream of front drafting rollers on the spinning machine without the need of accurately machined surfaces or extensive design.

8. An apparatus according to claim 7 wherein the pair of cooperating additional rollers are driven by simple means, already existing on the spinning machine, at fixed speed relationship to the speed of the front drafting rollers.

9. An apparatus according to claim 7 wherein the means is driven by frictional contact between one roller and one of the front drafting rollers.

0. An apparatus according to claim 9 wherein the surface speed at the nip of the roller means is determined by the driving surface of the driven roller having a greater diameter than its surface which forms the nip.

1 1 . A yarn structure produced by any of the apparatuses of claims 1 to 10.