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

Description

[0001] The invention relates to the manufacture of yarns from a well-aligned assembly of any type of staple fibre or fibre blend.

[0002] In the manufacture of staple fibre yarns from well-aligned fibres, the constituent fibres are processed such that they are firstly untangled and separated from each other in a carding process and then reassembled into a continuous structure in which the fibres are substantially mutually parallel. The parallel arrangement of the fibres is improved in the subsequent processes of drawing or gilling, which also serve to straighten fibres which may be individually hooked, and may be further improved during an optional combing process which also serves to remove very short fibre, small accumulations of fibre which may still be entangled, and pieces of non-fibrous foreign contaminant. After a series of such processes the fibres are assembled into a long continuous rope-like structure of the desired linear density appropriate to the particular spinning machine. Depending on the drafting system employed on the spinning machine, the fibre assembly may at this stage be either a sliver, or a lighter material known as roving. Roving may or may not contain twist, but even when twist is present the fibres remain highly parallel to each other in helical paths within the roving structure. Similarly after spinning the fibres remain in parallel helical paths within the yarn structure.

[0003] There are a number of reasons why care is taken in the preparation of a fibre assembly for spinning to ensure a high degree of parallelism between the fibres. Firstly, such well-aligned slivers and rovings allow drafting (attenuations) by high ratios, commonly in excess of 5:1, which contributes significantly to the economy of processing costs; secondly, a maximum of fibre extent is available to contribute to the tensile strength of the yarn; thirdly, the yarn is densely compacted, lean and smooth, which is desirable for the manufacture of compact cloths of smooth and clear finish; and fourthly, the finest yarn may be spun from a given fibre quality.

[0004] A yarn from such a well-aligned fibre assembly does, however, have some disadvantages. As a fibre is drawn from the fibre assembly into the twisting zone by the drafting means (usually a roller pair), its position relative to other fibres simultaneously being drawn into the yarn remains substantially constant, so that as it is twisted about other fibres in the twisting zone to form the spun yarn structure, it takes up a helical path of substantially constant radius. Consequently, the yarn is composed of fibres lying in parallel helical paths.

[0005] It will be readily understood that in a highly organised yarn structure in which the constituent fibres lie in parallel helical paths of constant radius, there is a very high probability that some fibres lie entirely on the yarn surface. Such fibres are held in place by virtue of being wrapped around other fibres within the body of the yarn and the stability of their position may be enhanced by setting (annealing) those fibres in their helical paths. In spite of this, because of the flexible nature of most fibres, surface fibres can be partially or completely stripped from the yarn by the frictional action of yarn guides during winding, and particularly by the scraping action of a loom reed during weaving. Further, the tensile strength and stability of such yarns depend only upon inter-fibre frictional forces deriving from the internal yarn pressure, which, in turn, derives from the helical fibre paths and fibre tension when the yarn is placed under a tensile stress. When the yarn is subjected to a cyclically varying stress, however, there can occur some incremental inter-fibre movement or drafting, leading eventually to yarn breakdown by drafting. This is accentuated when surface fibres are continually being stripped from the yarn which reduces the twist factor and hence reduces the internal yarn pressure. Further, fibres which lie wholly close to the yarn surface are subject to relatively few contacts with other fibres and so are more readily able to draft rather than develop tension when under stress. This lower level of tension in the outer fibres also leads to less inter-fibre pressure in the interior of the yarn and a higher propensity for drafting of fibres throughout the yarn structure. Yet another disadvantage of this structure is that many fibre ends tend to protrude above the yarn surface. Such protruding fibre ends or hairs can be easily snagged rendering even easier their removal from the yarn, or they can entangle with neighbouring yarns in applications such as a weaving warp, especially if the yarn is caused to rotate.

[0006] Yarns spun from well-aligned fibres by conventional means have a small degree of resistance to these problems because many fibres do not remain strictly at the same radius about the yarn axis, but may lie in a helical path of varying radius. This variation in radial position of the fibre is known as fibre migration. Two causes of migration which can occur during conventional spinning are described in the literature. The 'tension mechanism' is due to the tension of fibres on the outside of the forming yarn progressively increasing because of their greater path lengths so that they force their way inwards to replace inner fibres which have gone slack. It has been proposed that this mechanism is hindered by higher overall spinning tension. The 'geometric mechanism' occurs if the twisting is of a form known as the wrapped ribbon form and requires the fibres to change their position in the ribbon emerging from the front roller nip. In ring spinning, for example, the fibre position under the front roller nip is unlikely to change much because of the draft employed, and so the geometric mechanism is of little significance. These naturally occurring mechanisms of migration do not however result in a yarn capable of withstanding the vigorous mechanical action of certain processes such as weaving.

[0007] The weaving process includes an abrasive action on the warp by the reed and heddles, a cyclically varying tensile stress due to the shedding and beat-up motions, and a cyclic rotation (amounting to repeated untwisting and twisting of the yarn) due to the rubbing action of moving machine parts. Singles yarns spun from well-aligned slivers or rovings invariably fail during weaving by the mechanisms described above, and are almost universally considered unsuitable for weaving as warp. In order to overcome these deficiencies such yarns are commonly twisted together to form twofold or threefold yarn structures to be woven as warp. The relatively loosely bound surface fibres of a singles yarn then become bound by the other ply or plies so that they cannot be stripped off, and yarn breakdown during weaving is substantially eliminated. For this reason, worsted cloths are commonly woven using twofold yarns in the warp, but this expedient introduces further disadvantages. Apart from the added cost of the two-folding process there is a lower limit upon the weight per unit area of cloth which can be woven which depends primarily upon the linear density of the yarn.

[0008] The plying process may be imitated at the spinning frame by combining, within the twisting zone, two rovings initially separated in the drafting zone. GB-A-1318413 is an example of this. Superimposed on the net yarn twist is a small level of false twist which is generated in the two drafted strands which effect the entrapment of the surface fibres of one strand by the other strand. Further, loose surface fibres rotating about one strand are also trapped by the other strand. While this allows a more compact and slightly finer warp yarn to be produced it still requires two rovings to be prepared for each yarn, and still cannot be spun as fine as a conventional singles yarn.

[0009] As an alternative to plying the yarn it is known to apply an adhesive, usually natural or synthetic size, to the yarn surface in order to glue loosely bound surface fibres more securely in place, and so prevent their removal or entanglement with neighbouring yarns during the weaving process. Preferably the size solution will penetrate into the body of the yarn, coating all fibres to also reduce the risk of incremental drafting under the cyclically varying forces applied during weaving. However, this expedient has the disadvantages of the added costs of the sizing process, drying the sized yarn, and subsequently washing off the size during finishing the woven cloth.

[0010] An object of the present invention is to provide a yarn structure spun from a well-aligned sliver or roving, in which the fibres do not lie in parallel helical paths of constant radius and none of the fibres lie wholly on the yarn surface, and part, or parts, of every fibre is bound within the yarn structure by part or parts of other fibres in the yarn.

[0011] Another object of the invention is to provide in a singles yarn structure, a degree of additional fibre migration and inter-fibre entanglement to enhance the yarn performance by inhibiting removal of individual fibres from the yarn structure.

[0012] It is a further objective of the invention to provide a yarn structure which is resistant to many of the problems commonly associated with yarn spun from a well-aligned sliver or roving, such as fibre shedding during processing and loss of product appearance due to gradual breakdown of the yarn structure in service.

[0013] Another object of the invention is to provide a singles yarn structure, spun from a well-aligned sliver or roving, which is weavable directly as warp without the need of sizing or plying.

[0014] A further object of the invention is to provide a method and means for modifying the paths of fibres during, and as part of the spinning operation, so as to generate increased levels of fibre migration within the yarn structure.

[0015] This object may be achieved in a number of ways, for example by cyclically varying the tension of individual fibres as they enter the forming yarn; by bucking and disorienting the fibres before they receive twist; by arranging for small groups of sub-groups, of fibres to twist into discrete strands with false twist prior to the final convergence of all of the fibres into the yarn with real twist; or by any combination of these effects.

[0016] According to a first aspect of the invention, a yarn structure is provided spun from an aligned sliver or roving, wherein fibres of the sliver or roving after spinning do not lie in normal parallel helical paths of constant radius as the fibre geometry is disturbed by fibres which have been caused to migrate cyclically or randomly between the yarn surface and the interior of the yarn structure and none of the fibres lie wholly on the yarn surface and part, or parts of every fibre is bound within the yarn structure by part or parts of other fibres forming the yarn.

[0017] According to a second aspect of the invention there is provided a method for producing yarn according to the above wherein migration of fibres between the interior and the surface of the yarn is caused by cyclically varying the tension in individual fibres at a point of twist insertion such that a proportion of the fibres are subjected to high tension whilst simultaneously a second proportion of the fibres are subject to low, or zero, tension.

[0018] According to a third aspect of the invention, there is provided an apparatus for producing yarn comprising front drafting rollers to deliver a strand of fibres, said front drafting rollers forming a nip that constrains the fibres comprising the strand into a ribbon of finite width as they enter and emerge from the nip characterised by an oscillating guide sited downstream of the drafting rollers which is oscillated along a line, or within a plane, parallel to the nip of the rollers, so that when the guide is at its extreme left-hand position a fibre emerging from the nip at the right-hand side of the fibre stream is subjected to a high tension, whilst a fibre emerging from the left-hand side of the nip is at a low tension, and vice versa.

[0019] Further aspect of the invention will become apparent from the following description.

[0020] The present invention will now be described with reference to the attached drawings in which:

Figure 1 depicts in cross-section a nip of front drafting rollers of a worsted spinning machine, a spindle, the yarn path and an oscillating yarn guide;

Figure 2 depicts in plan the nip of the front drafting rollers, the location of fibres within that nip, and the path of the yarn through the oscillating yarn at the extreme positions of oscillation of the yarn guide;

Figure 3 depicts diagrammatically a short section of yarn and the path followed by two fibres in the yarn structure;

Figure 4 depicts in cross-section the nip of front drafting rollers of a staple fibre spinning machine, the nip of an additional pair of rollers, a zone of overfeed between the two roller nips, and the yarn path through that zone;

Figure 5 depicts in plan the nip of front drafting rollers of a staple fibre spinning machine, the nip of an additional pair of rollers, the location of fibres between the two nips, the path of the fibre stream between the two nips and one possible path of one fibre between the two nips; and

Figure 6 depicts in plan the location of fibres within the nip of front drafting rollers (or additional rollers), spread over a wide spacing with sub-groups of fibres twisting together under the action of false twist before all of the fibres become twisted together to form the yarn.

[0021] Referring now to Figure 1, a drafted strand of fibres 1 is delivered by the front drafting rollers 2 to pass through an oscillating guide 3, a pigtail guide 4, a further yarn guide 5 (such as a ring and traveller mechanism) which guides the spun yarn 11 to be wound onto a storage package on a spindle 6.

[0022] Referring now to Figure 2, the drafted strand 1 passing through the nip 7 of the front drafting rollers is spun into yarn 11 which then passes through the oscillating guide 3 which is shown in its extreme positions of oscillation. At the nip 7 of the front drafting rollers 2, the fibres comprising the drafted strand 1 are spread over a finite distance X as they enter and emerge from the nip 7. When the oscillating guide 3 is at its extreme left-hand position a fibre 9 emerging from the nip 7 at the right-hand side of the fibre stream 1 is subjected to a high tension, whilst a fibre 10 emerging from the left-hand side of the nip 7 is at low tension or slack. The difference in tension between fibres 9 and 10 causes the fibre 9 to migrate towards the core of the yarn 11 and the fibre 10 to migrate towards the surface of the yarn 11. When the oscillating guide 8 moves to its extreme right-hand position (dotted) fibre 10 is now tensioned, causing it to migrate towards the core of the yarn 11, whilst fibre 9 becomes slack causing it to migrate towards the surface of the yarn 11. All other fibres in the strand 1 between fibres 9 and 10 are also subjected to cyclic variations of tension, causing each of them to migrate to some degree within the body of the yarn 11, thereby disrupting the parallel fibre arrangement. Preferably the frequency of oscillation of guide 8 is such that fibres are caused to migrate between the surface and the core of the yarn at least three times over a distance along the yarn equal to the mean fibre length to ensure adequate fibre entrapment.

[0023] Referring now to Figure 3 the path of a fibre 10, delivered at the left-hand side of the fibre stream 1 in Figure 2, is depicted as a full line migrating from the surface of the yarn 11 to the core, back to the surface and finally back to the core. A fibre 9, delivered from the right-hand side of the fibre stream in Figure 2 is depicted as a broken line, following a similar path between the core and the surface of the yarn, but 180° out of phase with the path of fibre 10. Thus each of the fibres 9 and 10 become bound within the yarn structure, first the one by the other then the other by the one, successively, along the length of the yarn, and similarly acting upon and being acted upon by every other fibre within the yarn cross-section.

[0024] Referring now to Figure 4, an additional pair of nip rollers 12, immediately downstream of the front drafting rollers 2, is driven (by means not shown) at a surface speed less than the delivery speed of the front drafting rollers. The drafted strand 1 is now caused to buckle in the zone between the nips 7 and 13 of the two pairs of rollers and to migrate to-and-fro across the nip 13 of the additional rollers 12 in order to accommodate the lower speed of the additional rollers. Whilst fibres in the main stream of fibres migrate to-and-fro in order to effect passage of overfed fibre through the nips 13 of the slower rollers 12, a given fibre 14 (Figure 5) just entering the overfeed zone can cross that zone unimpeded at the delivery speed of the front drafting rollers 2 until it is caught up by the nip 13 of the additional rollers 12. In making that passage unimpeded the fibre 14 has the chance to change its position relative to the main stream of fibres 1, with the possibility of becoming located on the opposite side of the main fibre stream as shown, or at least located with some other different relativity. Similarly, a fibre leaving the grip of the front drafting rollers will no longer be under the influence of the buckling action and also has the chance to change its position relative to the main stream of fibres.

[0025] Further, fibres within the main stream may change their position relative to others under the buckling action as a consequence of their individual nature, variations in their bending rigidity along their length, fibre crimp and air turbulence in the region between the two nips.

[0026] By the above means, every fibre passing through the overfeed zone has the possibility of changing its relative position as the main fibre stream buckles, spreads under the buckling action and is caused to migrate to-and-fro within the nip of the additional rollers.

[0027] Referring now to Figure 6 which depicts in plan the fibres in the drafted strand 1 spread over a wide front of width X within the nip 7 of the front drafting rollers 2 (or similarly within the nip 13 of an additional pair of rollers 12), and being drawn together by the condensing action of twist into a yarn 11. When the fibre stream is spread over a wide enough distance X, sub-groupings 15 of fibres may form downstream of the roller nip 7 (13), the fibres in each sub-group becoming twisted together in separate sub-strands by false twist which generates by the action of spinning twist under these geometrical conditions. The magnitude of this effect increases with increasing fibre spread, so that when the fibre spread is of the order of several millimetres, the fibre sub-strands 15 behave as separate, very fine yarns before they are finally converged to form the yarn 11. Under these conditions some of the false twist in the separate fibre groupings becomes entrapped with the main structure of the yarn 11, either during build-up of the false twist or when the false twist is decaying due to changing geometry or size of the fibre sub-group. The false twist built into the yarn in this way will vary in both sense and intensity with an algebraic sum of zero in an infinite length of yarn, and will serve to bind individual fibres securely within the yarn structure. The sub-groups of fibres form and decay relatively rapidly and randomly, and individual fibres can migrate from one sub-group to another, contributing to two or more sub-groups within the yarn structure. Further, loose fibre ends protruding from the surface of a fibre sub-group will rotate with the rotating sub-group under the influence of twist insertion and will be constrained and possibly captured as they pass between neighbouring sub-groups. These trapped loose fibre ends will thus be bound into the yarn structure as the sub-groups converge thereby reducing yarn hairiness as well as increasing the overall fibre binding within the yarn structure.

[0028] 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.

[0029] 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.

[0030] 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.

Claims

1. A yarn structure (11) spun from an aligned sliver or roving (1), characterised in that fibres of the sliver or roving (1) after spinning do not lie in normal parallel helical paths of constant radius as the fibre geometry is disturbed by fibres (9,10) which have been caused to migrate cyclically or randomly between the yarn surface and the interior of the yarn structure and none of the fibres lie wholly on the yarn surface and part, or parts of every fibre is bound within the yarn structure by part or parts of other fibres forming the yarn (11).

2. A yarn structure (11) spun as claimed in claim 1, in which individual fibres (9,10) lie in paths which migrate cyclically or randomly between the surface of the yarn structure and the interior of the yarn structure with adjacent fibres in the yarn structure inter-entangled in sub groupings by twist, and with individual fibres contributing to two or more separate sub-groups of fibres, so that movement or withdrawal of individual fibres is impeded by the fibre geometry and inter-fibre entanglement.

3. A method for producing yarn (11) according to claim 1, characterised in that migration of fibres (9,10) between the interior and the surface of the yarn is caused by cyclically varying the tension in individual fibres at a point of twist insertion such that a proportion of the fibres are subjected to high tension whilst simultaneously a second proportion of the fibres are subject to low, or zero, tension.

4. A method according to claim 3 wherein cyclic variations in fibre tension are realised by withdrawing yarn (11) from front drafting, or delivery, rollers (2) at a continuously varying angle, acute to the normal direction of withdrawal.

5. A method according to claim 4 wherein the continuously varying angle of withdrawal of the yarn is determined by an oscillating yarn guide (3) situated downstream of the point of twist insertion.

6. A method for producing yarn according to claim 1, comprising the steps of drafting the fibres in a fibre stream (1) and providing an overfeed zone (7,13) through which the drafted fibres must pass in a twistless state, with at least a proportion of the fibres in a tensionless or overfeed condition whereby fibres (9,10) are caused to migrate continuously between the interior and the surface of the yarn (11).

7. A method according to claim 6 including a step of causing part or parts of the fibres entering the overfeed zone (7,13) to deviate from a straight-line path through the zone.

8. A method according to claims 6 and 7 including a step of causing the fibre stream (1) to buckle and spread within, and be delivered from, the overfeed zone (7,13) over a wide front.

9. A method according to any one of claim 6 to 8 including a step of causing twist between the fibres to form a yarn (11) downstream of the point of emergence from the overfeed zone.

10. A method according to any one of claims 6 to 9 including causing individual fibres (1) entering the overfeed zone (7,13) to deviate from the instantaneous path of the main fibre stream, changing its relative position in the fibre stream.

11. A method according to any one of claims 6 to 10 including causing fibres (1) delivered from the overfeed zone (7,13) to twist together over a short length in sub-groupings (15) to form sub-strands of length less than the fibre length under the influence of false-twist deriving from the spinning action and the geometrical conditions.

12. An apparatus for producing yarn according to claim 1 comprising front drafting rollers (2) to deliver a strand of fibres (1), said front drafting rollers (2) forming a nip (7) that constrains the fibres comprising the strand (1) into a ribbon of finite width as they enter and emerge from the nip (7)
   characterised by
      an oscillating guide (3) sited downstream of the drafting rollers (2) which is oscillated along a line, or within a plane, parallel to the nip of the rollers (2), so that when the guide (3) is at its extreme left-hand position a fibre (9) emerging from the nip (7) at the right-hand side of the fibre stream (1) is subjected to a high tension, whilst a fibre (10) emerging from the left-hand side of the nip (7) is at a low tension, and vice versa.

13. An apparatus according to claim 12 wherein the yarn guide (3) is oscillated at a frequency sufficient to provide at least three oscillations during delivery of a yarn length equal to the mean length of fibres in the yarn.

14. An apparatus for producing yarn according to claim 1 which comprises a pair of nip rollers (2) and means for delivering fibres to said nip roller pair at a speed slower than the surface speed of said nip roller pair.

15. An apparatus according to claim 14 wherein the means is a pair of rollers (12) sited downstream of the front drafting rollers (2).

16. An apparatus according to claim 15 including means for driving one of the pair of rollers at a surface speed slower than that of the front drafting rollers.

Ansprüche

1. Garnstruktur (11), die aus einem ausgefluchteten Faserband oder Vorgarn (1) gesponnen ist,
dadurch gekennzeichnet,
daß die Fasern des Faserbandes oder Vorgarnes (1) nach dem Spinnen nicht in normalen parallelen wendelförmigen Bahnen mit konstantem Radius liegen, da die Fasergeometrie durch Fasern (9, 10) gestört ist, die veranlaßt worden sind, zyklisch oder zufällig zwischen der Garnoberfläche und dem Inneren der Garnstruktur zu migrieren, und daß keine der Fasern vollständig auf der Garnoberfläche liegt und ein Teil oder Teile von jeder Faser innerhalb der Garnstruktur von einem Teil oder Teilen von anderen Fasern gebunden ist, welche das Garn (11) bilden.

2. Gesponnene Garnstruktur (11) nach Anspruch 1,
bei dem einzelne Fasern (9, 10) in Bahnen liegen, welche zyklisch oder zufällig zwischen der Oberfläche der Garnstruktur und dem Inneren der Garnstruktur migrieren, wobei benachbarte Fasern in der Garnstruktur in Untergruppen durch Zwirnen miteinander verschlungen sind, und wobei einzelne Fasern zu zwei oder mehreren separaten Untergruppen von Fasern beitragen, so daß eine Bewegung oder ein Herausziehen von einzelnen Fasern durch die Fasergeometrie und die wechselseitige Verschlingung der Fasern verhindert ist.

3. Verfahren zum Herstellen eines Garnes (11) nach Anspruch 1,
dadurch gekennzeichnet,
daß die Migration von Fasern (9, 10) zwischen dem Inneren und der Oberfläche des Garnes hervorgerufen wird durch zyklisches Variieren der Spannung in einzelnen Fasern an einer Stelle der Drallerteilung, so daß ein Anteil der Fasern einer hohen Spannung ausgestzt wird, während gleichzeitig ein zweiter Anteil der Fasern einer geringen Spannung oder einer Spannung von Null ausgesetzt wird.

4. Verfahren nach Anspruch 3,
wobei die zyklischen Variationen der Faserspannung realisiert werden durch Herausziehen des Garnes (11) aus den vorderen Streckwalzen oder Zuführungswalzen (2) unter einem sich kontinuierlich änderenden spitzen Winkel gegenüber der normalen Richtung des Herausziehens.

5. Verfahren nach Anspruch 4,
wobei der sich kontinuierlich ändernde Winkel beim Herausziehen des Garnes durch eine oszillierende Garnführung (3) bestimmt wird, die sich stromabwärts von der Stelle der Drallerzeugung befindet.

6. Verfahren zum Herstellung von Garn gemäß Anspruch 1,
das die Schritte des Streckens der Fasern in einem Faserstrom (1) und des Vorsehens einer Voreilungszone (7, 13) umfaßt, durch welche die gestreckten Fasern in einem ungezwirnten Zustand hindurchgehen müssen, wobei zumindest ein Anteil der Fasern in einem spannungslosen oder Voreilungszustand ist, so daß die Fasern (9, 10) dazu veranlaßt werden, kontinuierlich zwischen dem Inneren und der Oberfläche des Garnes (11) zu migrieren.

7. Verfahren nach Anspruch 6,
das einen Schritt umfaßt, bei dem ein Teil oder Teile der Fasern, die in die Voreilungszone (7, 13) eintreten, dazu veranlaßt werden, von einer geradlinigen Bahn durch die Zone abzuweichen.

8. Verfahren nach Anspruch 6 und 7,
das einen Schritt umfaßt, bei dem der Faserstrom (1) dazu gebracht wird, sich innerhalb der Voreilungszone (7, 13) über eine breite Front zu verziehen und zu verteilen, und aus dieser zugeführt zu werden.

9. Verfahren nach einem der Ansprüche 6 bis 8,
das einen Schritt umfaßt, bei dem ein Verzwirnen zwischen den Fasern zur Bildung eines Garnes (11) stromabwärts von der Stelle des Austritts aus der Voreilungszone hervorgerufen wird.

10. Verfahren nach einem der Ansprüche 6 bis 9,
das einen Schritt umfaßt, bei dem einzelne Fasern (1), die in die Voreilungszone (7, 13) eintreten, dazu gebracht werden, von ihrer momentanen Bahn des Hauptfaserstromes abzuweichen, wobei sie ihre relative Position in dem Faserstrom ändern.

11. Verfahren nach einem der Ansprüche 6 bis 10,
das einen Schritt umfaßt, bei dem die aus der Voreilungszone (7, 13) gelieferten Fasern (1) dazu gebracht werden, sich über eine kurze Länge in Teilgruppen (15) zu verzwirnen, um Teilstränge mit geringerer Länge als der Faserlänge unter dem Einfluß einer Vordrehung zu bilden, was sich aus der Spinnwirkung und den geometrischen Zuständen ergibt.

12. Vorrichtung zum Herstellung von Garn
gemäß Anspruch 1,
die vordere Streckwalzen (2) aufweist, um einen Strang von Fasern (1) zu liefern, wobei die vorderen Streckwalzen (2) einen Walzenspalt (7) bilden, der die Fasern, welche den Strang (1) bilden, in einem Band mit endlicher Breite einspannt, wenn sie in den Walzenspalt (7) eintreten und aus diesem austreten,
gekennzeichnet durch
eine oszillierende Führung (3), die sich stromabwärts von den Streckwalzen (2) befindet und die längs einer Linie, oder innerhalb einer Ebene, parallel zu dem Walzenspalt der Walzen (2) oszilliert, so daß dann, wenn die Führung (3) sich in ihrer extrem linken Stellung befindet, eine aus dem Walzenspalt (7) austretende Faser (9) auf der rechten Seite des Faserstromes (1) einer hohen Spannung ausgesetzt ist, während eine Faser (10), die auf der linken Seite des Walzenspaltes (7) austritt, einer geringen Spannung ausgesetzt ist, und umgekehrt.

13. Vorrichtung nach Anspruch 12,
wobei die Garnführung (3) mit einer Frequenz oszilliert, die ausreichend ist, um für mindestens drei Oszillationen während der Zuführung einer Garnlänge zu sorgen, welche gleich der mittleren Länge von Fasern in dem Garn ist.

14. Vorrichtung zum Herstellen von Garn gemäß Anspruch 1,
die ein Paar von Walzenspaltwalzen (2) sowie eine Einheit aufweist, um die Fasern dem Paar von Walzenspaltwalzen mit einer Geschwindigkeit zuzuführen, die geringer ist als die Oberflachengeschwindigkeit des Paares von Walzenspaltwalzen.

15. Vorrichtung nach Anspruch 14,
wobei die Einrichtung ein Paar von Walzen (12) aufweist, die sich stromabwärts von den vorderen Streckwalzen (2) befinden.

16. Vorrichtung nach Anspruch 15,
die eine Einrichtung aufweist, um eine von dem Paar von Walzen mit einer Oberflachengeschwindigkeit anzutreiben, die geringer ist als die der vorderen Streckwalzen.

Revendications

1. Structure formant fil (11) filée à partir d'un ruban ou d'une mèche (1) aligné, caractérisée en ce que les fibres du ruban ou de la mèche (1), après filage, ne s'étendent pas selon des trajectoires hélicoïdales parallèles normales de rayon constant car la géométrie des fibres est perturbée par des fibres (9,10) qui ont été poussées à migrer de manière cyclique ou aléatoire entre la surface du fil et l'intérieur de la structure formant fil et aucune des fibres ne s'étend entièrement à la surface du fil et une ou des partie (s) de chaque fibre est liée à l'intérieur de la structure formant fil par une ou des partie (s) d'autres fibres formant le fil (11).

2. Structure formant fil (11) filée selon la revendication 1, dans laquelle des fibres simples (9,10) s'étendent suivant des trajectoires qui migrent de manière cyclique ou aléatoire entre la surface de la structure formant fil et l'intérieur de la structure formant fil, des fibres adjacentes dans la structure formant fil étant entremêlées entre elles en sous-groupes par torsion, et des fibres simples contribuant à constituer deux sous-groupes distincts de fibres ou plus, de telle sorte que le déplacement ou l'étirage des fibres individuelles est empêché par la géométrie des fibres et l'enchevêtrement entre les fibres.

3. Procédé destiné à produire un fil (11) selon la revendication 1,
caractérisé en ce que la migration des fibres (9,10) entre l'intérieur et la surface du fil est obtenue en faisant varier de manière cyclique la tension dans les fibres individuelles à un point d'insertion de la torsion de sorte qu'une partie des fibres est soumise à une tension élevée alors que parallèlement une deuxième partie des fibres est soumise à une tension faible, voire nulle.

4. Procédé selon la revendication 3 dans lequel les variations cycliques de tension des fibres sont obtenues en étirant le fil (11) à partir des cylindres étireurs ou d'alimentation (2) suivant un angle aigu par rapport au sens normal d'étirage qui varie en permanence.

5. Procedéselon la revendication 4, dans lequel l'angle d'étirage du fil qui varie en permanence est déterminé par un guide fil oscillant (3) situé en aval du point d'insertion de la torsion.

6. Procédé destiné à produire un fil selon la revendication 1, comprenant les étapes destinées à étirer les fibres en une mèche de fibres (1) et former une zone de suralimentation (7, 13) à travers laquelle les fibres étirées doivent passées dans un état non torsadé, au moins une partie des fibres n'étant pas sous tension ou étant en suralimentation, état selon lequel les fibres (9,10) sont poussées à migrer en permanence entre l'intérieur et la surface du fil (11).

7. Procédé selon la revendication 6, comprenant l'étape destinée à entrainer une ou des partie(s) de fibres à pénétrer dans la zone de suralimentation (7, 13), pour dévier d'une trajectoire en ligne droite à travers la zone.

8. Procédé selon les revendications 6 et 7, comprenant une étape destinée à entraîner la mèche de fibres (1) à se déformer et s'étendre à l'intérieur de la zone de suralimentation (7,13) et être alimentée à partir de cette dernière sur un large front.

9. Procédé selon l'une quelconque des revendications 6 à 8, comprenant une étape destinée à obtenir une torsion entre les fibres pour former un fil (11) en aval du point d'émergence de la zone de suralimentation.

10. Procédé selon l'une quelconque des revendications 6 à 9, comprenant une étape destinée à pousser des fibres simples (1) pénétrant dans la zone de suralimentation (7,13) à dévier de la trajectoire instantanée du ruban principal de fibres, modifiant leur position relative dans la mèche de fibres.

11. Procédé selon l'une quelconque des revendications 6 à 10, comprenant l'étape destinée en entraîner les fibres (1) alimentées à partir de; la zone de suralimentation (7,13) à se tordre ensemble sur une courte longueur en sous-groupes (15) afin de former des sous-mèches d'une longueur inférieure à la longueur des fibres sous l'influence d'une fausse torsion dérivant de l'action de filage et des conditions géométriques.

12. Appareil pour produire un fil selon la revendication 1 comprenant des cylindres étireurs (2) pour livrer une mèche de fibres (1), lesdits cylindres étireurs (2) formant un point de pinçage (7) qui contraint les fibres comprenant la mèche (1) en un ruban de largeur finie alors qu'elles pénètrent et émergent du point de pinçage (7)
   caractérisé par
   un guide oscillant (3) placé en aval des cylindres étireurs (2), lequel oscille suivant une ligne, ou dans un plan, parallèle au point de pinçage des cylindres (2), de sorte que lorsque le guide (3) est dans sa position extrême gauche, une fibre (9) émergeant du point de pinçage (7) du côté droit de la mèche de fibres (1) est soumise à une forte tension, alors qu'une fibre (10) émergeant du côté gauche du point de pinçage (7) est sous faible tension, et vice versa.

13. Appareil selon la revendication 12, dans lequel le guide fil (3) oscille à une fréquence suffisante pour atteindre au moins trois oscillations pendant l'alimentation d'un fil d'une longueur égale à la longueur moyenne des fibres du fil.

14. Appareil pour produire un fil selon la revendication 1, lequel comprend une paire de cylindres de pinçage (2) et des moyens pour alimenter les fibres à ladite paire de cylindres de pinçage à une vitesse inférieure à la vitesse de surface de ladite paire de cylindres de pinçage.

15. Appareil selon la revendication 14, dans lequel les moyens sont une paire de cylindres (12), placés en aval des cylindres étireurs (2).

16. Appareil selon la revendication 15, comprenant des moyens pour entraîner un des cylindres de la paire à une vitesse de surface inférieure à celle des cylindres étireurs.

Drawing