EP0201357B1

EP0201357B1 - Vacuum spinning of fasciated yarn

Info

Publication number: EP0201357B1
Application number: EP86303567A
Authority: EP
Inventors: Danny R. Bradley; N. Page Hardy; Elbert Flemming Morrison; D.C. Reece
Original assignee: Burlington Industries Inc
Current assignee: Burlington Industries Inc
Priority date: 1985-05-09
Filing date: 1986-05-09
Publication date: 1991-08-21
Anticipated expiration: 2006-05-09
Also published as: BR8602073A; DE3680706D1; CN86103633A; EP0201357A3; CN1021065C; JPH07100886B2; KR860009164A; CA1317169C; EP0201357A2; JPS61275435A

Description

This invention relates to the vacuum spinning of fasciated yarn. In US-A-4507913 there are disclosed methods and apparatus for efficiently and effectively producing yarn having properties approaching those of ring spun yarn, but at much greater speeds. The basic technique disclosed in the patent is known as "vacuum spinning", and has a number of advantages compared to conventional techniques.

Until relatively recently, ring spinning equipment has made up approximately 90 percent of all spinning equipment. However several new high speed procedures have recently been utilized including open end spinning, friction spinning, hollow core spinning, and air jet spinning. None of these new commercial systems has been successful in the production of long staple yarn, however, especially for apparel fabrics. However vaccuum spinning is capable of producing long staple yarn suitable for use in apparel fabrics, the yarn approaching the properties of ring spun yarn.

Vacuum spinning has a number of advantages compared to conventional ring spinning. These include the following. Productivity can be expected to be at least 6-8 times that of commercial ring spinning. Despite this increased productivity, the properties of the yarn are more like ring spun yarn than open end air jet type yarns. The horsepower per pound of yarn produced is considerably less than that for air jet spinning using compressed air.

Vacuum spinning lends itself to automatic end piece-up, automatic slubbing, automatic adaptation, the production of large delivery packages, and the utilization of large supply packages (e.g. 25 lb. (11 kg) cans of sliver). A wide count range can be provided on long staple yarns, at least 1/8's to 1/60's on 55 per cent polyester/45 per cent wool, and at least 1.8's to 1/40's on 100 per cent wool. There are lower labour costs per kilogramme of yarn produced compared to ring spun yarn.

EP-A-184277 (State of the art pursuant to Art. 54(3) EPC) discloses apparatus for forming yarn from fibres, comprising an elongate rotary hollow shaft, a through passageway, extending through the shaft between a first end and a second end of the shaft, at least a portion of the surface of the shaft including perforations, means for passing the fibres through the passageway from the first end to the second end, means for rotating the shaft and means for applying a vacuum to the exterior of the shaft towards the perforations, the passageway including a relatively enlarged cross-sectional area portion adjacent the first end of the passageway, whereby at least some of the fibres are caused to extend outwardly and wrap around a core of fibres as the core passes through the passageway.

According to the invention the enlarged cross-sectional area portion is generally conical in shape and is arranged so that the reduced cross-sectional area portion thereof faces towards the second end of the passageway.

Preferably the conical portion comprises a right circular cone, the centre of which is disposed in alignment with the first and second ends and the perforations of the shaft are generally wedge-shaped in longitudinal section and extend through the wall of the shaft in the region of the conical portion.

Advantages of the invention are that it lends itself to high draft ratios (e.g. 10-80); it can be modified to run both long and short staple yarns; and it can make yarn having either "S" or "Z" twist. A number of unique novelty yarns can be produced. The apparatus is simple and easy to maintain, and the noise level can be controlled by locating the vacuum pump in a separate location, to thereby ensure compliance with OSHA regulations. The apparatus runs cleanly since the vacuum automatically removes lint fly, and like contaminants, and oily waste is not introduced. Waste is reduced due to draft zone stoppage on end breaks, with a reduction in end breakage of about 400 per cent compared to ring spinning since there is no tension in the yarn. Also thread-up of the broken ends can be accomplished with minimum operator intervention. The apparatus can be run using higher weight sliver, (e.g. 55 grains per yarn compared to 35-40 grains per yarn which is conventional), and carpet yarn can be produced too by lengthening the draft zone and providing a larger nozzle. Yarn steaming may not be required for most counts-blends for handling, although it may be required for uniform dyeability, and steaming is easy to effect.

The yarn produced by the apparatus of the present invention includes core fibres and wrapper fibres. The wrapper fibres are predominantly individual fibres, although there are some groups of wrapper fibres. The groups of wrapper fibres appear as non-uniform, non-consistent fibre groupings, and provide a relatively smooth surface. The core fibers, on the other hand, are essentially parallel with the wrapper fibers uniformly distributed therearound. The fasciated yarn thus looks most like ring spun yarn of the commonly known yarns, although it is distinct in appearance from ring spun yarn too. For instance the yarn looks more like ring spun yarn than core spun, open-end, Murata jet spun, Toray, or DREF II prior art yarns.

The fasciated yarn as set forth above, includes essentially parallel core staple fibers. There is a uniform distribution of staple fiber wrapper fibers around the core fibers, the wrapper fibers being wrapped at a helix angle of about 30^o, and with about 20-30 percent of the fiber mass comprising wrapper fibers.

The fasciated yarn can also be described as a yarn having a core of essentially parallel staple fibers with the wrapped staple fibers disposed around the core forming a helix angle in the range of about 30-50^o, and the wrapped fibers are devoid of tucked or reverse wrapped fibers and are essentially devoid of auger or corkscrew appearing wrapped fibers. Rather the wrapped fibers have a smooth appearance.

The fasciated yarn can be produced with the predominant proportion of staple fibers of the core and covering as non-thermoplastic staple fibers. While the predominant proportion of the core and wrapped fibers can be selected from the group consisting of cotton, wool, rayon, mohair, flax, ramie, silk and blends thereof, the yarn also can be constructed using some, or all, thermoplastic fibre, such as acrylic, polyester, and other thermoplastic fibres or blends thereof.

The yarn produced by the apparatus and method of the present invention has surprising and desirable strength. For instance yarn produced from a 1/18's count of 45 per cent polyester and 55 per cent wool will have a minimum gram break strength of about 500, while yarn with the same count made of 100 per cent wool will have a minimum gram break strength of at least about 175. Thus, even when made from 100 per cent wool the yarn is suitable for making apparel fabrics.

The apparatus according to the present application also have basically all the same advantages described about with respect to vacuum spinning in general. Additionally, in the production of yarn from roving it is possible to construct the "nozzle" of the vacuum spinning apparatus in a simpler and more advantageous manner. By providing an interior generally conically shaped vacuum reservoir, instead of a spherical vacuum reservoir, ease of production is facilitated and a yarn having a slightly better break strength can be produced.

Further, the production of yarn directly from sliver is facilitated.

The particular "nozzle" for producing yarn having good strength properties directly from sliver, preferably includes a generally conically shaped interior chamber. The perforations in communication with the interior chamber are generally wedge-shaped, and the size of the interior passageway in the shaft adjacent the first end thereof is very large compared to the diameter of the shaft passageway between the interior chamber and the second end of the shaft, and may have the shape of a right circular cone frustum. The interior chamber is dimensioned so that it is large enough to allow free fibre movement so that the fibres will be lifted up and wrap around a core of the fibre mass more securely; however the interior should not be so big the fibres will be pulled through the perforations by the vacuum source. The perforations and the passageway between the first end of the shaft and the perforations, are dimensioned so that optimal wrapping action can be achieved. That is, the dimensions are large enough so that they allow sufficient air flow that they do not prevent the attainment of optimal fibre wrapping action. In this way optimal wrap for any given application may be achieved.

The invention will now be described by way of example with reference to the drawings, in which:

Figure 1 is a microphotograph at approximately 70x magnification of vacuum spun yarn produced according to the present invention;

Figure 2 is a microphotograph of the same yarn as Figure 1 only at a magnification of 35x;

Figures 3 through 8 are microphotographs of other, conventional, spun yarns made respectively by core spinning, open-end, ring spun, MJS, Toray, and DREF II techniques respectively;

Figure 9 is a side view of exemplary apparatus according to the present invention, shown in schematic co-operation with a vacuum source and feed roller;

Figure 10 is a side cross-sectional view of an exemplary "nozzle" for use with the apparatus of Figure 9;

Figures 11 to 16 are side schematic cross-sectional views of exemplary other forms of "nozzles" that may be utilised in vacuum spinning procedures.

The basic vacuum spinning apparatus 14 illustrated in Figure 9 is similar to that shown in US-A-4507913. The apparatus 14 comprises an outer housing 16, of metal, ceramic, or the like, which is operatively connected up through integral nipple 17 to a vacuum source 18, such as a vacuum pump which provides 50.4 cm (20 inches) of mercury at 19 cfm (or more). The interior of the housing 16 is hollow. The interior "nozzle" of the apparatus 14 is indicated generally by reference numeral 20, and includes a first end 21 thereof and a second end 22. At the second end 22 a gear 24 is mounted, which is connected to appropriate other gears and drives (not shown) for effecting rotation of the "nozzle" 20. The drives can rotate the "nozzle" 20 either clockwise or counterclockwise to provide either a Z or S twist, as desired.

From a draft system (not shown) a sliver S passes through the nip of the front feed rolls 26, and the produced yarn Y exits from the second end 22 of the apparatus 14.

A "nozzle" 20 for the production of yarn from sliver is shown in detail in Figure 10. The "nozzle" 20 comprises an elongate hollow shaft 30 having a first end 21 and a second end 22. A through-extending passageway goes from the end 21 to the end 22. The passageway includes a first portion 31 adjacent the first end 21, an interior chamber portion 32 close to, but spaced from, the first end 21, and a third portion 33 that extends from the portion 32 all the way to the second end 22. In the specific embodiment illustrated in Figure 10, the diameter of the portion 33 is 0.16 cm (1/16th inch) and is substantially constant.

Mounting the shaft within the casing 16 for rotation preferably bearings 35, 36 are provided. An annular shaped flange 37 extends outwardly from, and is integral with, the shaft 30 adjacent the end 22 and the bearing 36 abuts the flange 37. The exterior cylindrical surface 38 of the shaft 30 the gear 24 is press-fit so that rotation of the gear 24 effects rotation of the shaft 30.

The shaft 30 illustrated in Figure 10 is one that is particularly adapted for forming yarn Y from a sliver, rather than from a roving. The production of yarn directly from sliver, instead of from roving of course has a number of advantages since it essentially eliminates a step (and the associated equipment for performing the step) in the yarn formation process. It has been found that in the production of yarn from sliver, instead of from a roving, it is necessary to maximise the air flow from the first end 21 to the vacuum source 18, while still providing a restricted enough path for the movement of the fibres so that they are not pulled out of the shaft 30 by the vacuum. In the specific embodiment illustrated in Figure 10, this maximized air flow is provided by making the dimensions of the first passageway section 31 very large compared to the section 33, and providing perforations 40 that have a total effective area generally comparable to the effective operative area of flow in the passageway section 31, so that optimum wrap of fibres is achieved.

The passageway section 31 is substantially circular in cross-section, and for the embodiment illustrated in Figure 10 has a diameter of about 0.98 cm (0.387 inches) with the outside diameter of the shaft 30 at that point being about 1.27 cm (0.5 inches). The intermediate portion 32 of the passageway has a generally conical configuration, in essence having the configuration of a right circular cone. The passageway portion 32 is dimensioned so that it comprises a means for allowing free fibre movement therewithin, so that the fibres can be lifted up a substantial distance to wrap around the core during the production of the yarn Y from sliver S. For the particular structure illustrated in Figure 10, the passageway sections 31, 32 may be formed as follows:

Using a number 4 centre drill, then end 21 is concentrically penetrated to a depth of about 1.29 cm (0.51 inches)
Using a 0.59 cm (15/64 inch) drill, the end 21 is concentrically re-penetrated to the depth of about 1.26 cm (0.497 inches)
Using a 0.64 cm (1/4 inch) end drill, the end 21 is concentrically penetrated to a depth of about 1.07cm (0.42 inches)
Using a 0.95 cm (3/8 inch) 60^o countersink, the end 21 is again concentrically penetrated to a depth of 1.32 cm (0.52 inches)

Passageway section 33 is formed merely by concentrically penetrating the end 22 with a 0.6 cm (1/16 inch) drill, and drilling all the way to the preformed passageway portion 32. Typical other dimensions of the shaft 30 are as follows: the distance 42 equals about 0.95 cm (3/8 inch); the diameter of the end 22 is about 1.28 cm (0.503 inches); the thickness of the flange 37 is about 0.3175 cm (0.125 inches); the diameter of the portion receiving the bearing 36 is about 1.27 cm (0.501 inches); and the length of the shaft 30 from the beginning of the flange 37 is about 3.96 cm (1.5625 inches).

Note that there is a tapered wall portion between the passageway section 32 at the perforations 40 and the passageway section 33, this tapered wall portion being illustrated by reference numeral 44 in Figure 10. The provision of this tapered wall, compared to the same configuration of the shaft 30 without the tapered wall, leads to significantly better results.

For the embodiment illustrated in Figure 10 the perforations 40 are preferably four in number, and are evenly spaced around the periphery of the shaft 30. Each perforation 40 is generally wedge-shaped. The width of each of the perforations 40 at the exterior surface of the shaft 30, which width is indicated generally by reference numeral 46, is about 86.36 cm (34 inches). Each of the perforations 40 is formed by drilling an opening from the circumference to the passageway section 32 with a 0.24 cm (3/32 inch) drill at about a 34^o angle, and then reaming to the vertical to form the surface 48 which is essentially perpendicular to an extension of the passageway third portion 33. The results achieved by providing the face 48 generally perpendicular to the passageway section 33 are significantly improved compared to the situation where the 0.24 cm (3/32 inch) hole is drilled at a 34^o angle and there is no reaming.

Other illustrative configurations of nozzles which may be utilized according to the present invention are illustrated in Figures 11 to 13. While all of these nozzles are useful in forming yarn, it will be seen from the comparative test results for these nozzles that some produce yarn having significantly better properties than others.

The nozzle 320 illustrated in Figure 11 has a passageway portion 333 communicating with the second end 322 thereof that is 0.16 cm (1/16 inch) in diameter. Adjacent the first end 321 thereof the passageway portion 331 is about 0.32 cm (1/8 inch) in diameter. Between the passageway portions 331, 333, is a 0.64 cm (1/4 inch) diameter spherical vacuum reservoir 332, with four 0.16 cm (1/16 inch) diameter angled perforations 340 extending outwardly from the reservoir 332.

The nozzle 420 of Figure 12 has a passageway portion 433 that is 0.16 cm (1/16 inch) in diameter, and a passageway portion 431 which is 0.32 cm (1/8 inch) in diameter. The passageway portion 432 may be considered a vacuum reservoir, and has a conical shape. Four 0.16 cm (1/16 inch) angled perforations 440 are provided in communication with the reservoir 432.

The Figure 13 nozzle 520 is essentially identical to the nozzle 20 illustrated in Figure 10 (note that the showing in Figure 13 is schematic), except that the entire passageway section 531 has the shape of a cone frustum, and the shape of the passageway section 532 - and the exact points that the perforations 40 come off of it - are slightly different.

The nozzles illustrated in Figures 11 and 12 are suitable for use in forming yarn from roving, but do not form particularly strong or useful yarns from a sliver. However the nozzles 520 of Figure 13 and 20 of Figure 10, are capable of forming strong yarns from sliver, having an increased total air flow from the first end thereof through the perforations to the vacuum source 18. Also the middle sections of the passageways (32,532) allow free fibre movement so that the fibres will be lifted up and wrap around the core more securely. However the passageways 32,532 are not so big that the fibres will be pulled through the perforations 40,540 by the vacuum from source 18. Also in these embodiments the perforations collectively have effective cross-sectional areas relative to the effective cross-sectional area of the passageway section between the first end of the shaft and the perforations so that the dimensions of the perforations and passageway section are not a limiting factor in attaining optimal wrapping action of the fibres. In this way optimal wrap for any given application may be achieved.

The following Table I gives the results of tests that have been done on the nozzles of Figures 11 through 13 utilizing the same composition of feed materials. In each case 1/19's poly/wool feed fibres were utilized, 55% 3dx3 1/2"x4 1/2" T-655 Dacron Natural (polyester), and 45% WP644 Wool Natural. The vacuum source 18 in each case applied a vacuum of about 35.6-38.1 cm (14-15 inches) of mercury, but the volume of air flow was significantly greater for the Figure 13 embodiment than for the other embodiments.

Surprisingly, the breaking strength of the yarn produced by the nozzle of Figure 13 directly from sliver was greater than the breaking strength of the yarn produced from roving utilizing the nozzle of Figure 12 (which is similar in construction to that of Figure 13). Note that the nozzles of Figure 11 is suitable for use with a diffuser, while those of Figures 12 and 13 are not designed for use with a diffuser.

Note also that the generally conically shaped passageway section (vacuum reservoir) 432 of the Figure 12 nozzle achieves a yarn of higher break strength than for the spherical vacuum reservoir 332 embodiment of Figure 13. Vacuum reservoirs 332, 432 also have other functions, such as providing a chamber (volume) for radial deflection of the fibres so that the wrapping function is facilitated.

The apparatus according to the present invention thus includes an elongate hollow shaft 30 having first end 21 and a second end 22, with a through-extending passageway 31, 32, 33. At least a portion of the entire circumference is perforated, by perforations 40. Means for mounting the shaft for rotation comprise the bearings 35, 36 and the housing 16 and means for rotating the shaft about its axis comprise the gear 24 and associated powered components (not shown). The feed rolls 26, and other components, comprise means for passing textile fibres S through the passageway 31-33 of the shaft 30, linearly, generally along the axis of rotation thereof, the fibres being fed into the first end 21. The source 18 applies a vacuum to the exterior of the shaft 30 so that at least some of the fibres are free ends of fibres passing through the shaft will be drawn toward the shaft perforations 40, and will be caused to rotate with the shaft as the fibres move linearly generally along the axis of rotation, the passageway portion 32 allowing sufficient volume for the fibres to lift and wrap around the core. Withdrawing rollers, or like conventional components are provided as means for withdrawing the formed yarn Y from the end 22. Utilizing the embodiment illustrated in Figures 10 and 13, it is possible to make yarn having properties approaching that of ring spun yarn directly from sliver.

In tests run utilizing the nozzles of Figures 14 through 16 respectively, with different blends and worsted counts of yarn, the following results were obtained (all results plus or minus E and "SS" means "short staple"):

As can be seen from the test results, the yarn produced according to the present invention has a break strength comparable to a break strength of at least 500 gram break strength denier for a yarn produced from 1/18's count fibres of 55 per cent polyester and 45 per cent wool. Tests were also conducted utilizing a nozzle like that of Figure 15 only having the actual chamber construction like that of chamber 646 of Figure 16. In such tests, when yarn with a blend of 45 per cent polyester and 55 per cent wool was spun from sliver with a count of 1/18's the gram break strength was 518 and the elongation 8.4 per cent. When spun from 100 per cent wool sliver with the same count the gram break strength was 248 and the elongation 14.1 per cent. Thus by practicing the invention, too, it is possible to produce yarn having sufficient strength to be used as an apparel fabric from non-thermoplastic staple fibres.

Note that the nozzle 620 of Figure 14 has a passageway portion 624 communicating with a second end thereof, and a passageway portion 621 communicating with a first end thereof. Between the passageway portions 621, 624 a 0.64 cm (1/4 inch) diameter spherical vacuum reservoir 622 is provided with four 0.16 cm (1/16 inch) diameter angled perforations 623 extending outwardly from the reservoir 622.

In Figure 15, the nozzle 630 has a first passageway section 631 that has the shape of a cone frustum and a second passageway section 634 that is comparable to the passageway 624 of the Figure 14 embodiment. It also has an intermediate passageway portion 632 that may be considered a vacuum reservoir, which has a conical shape, with four 0.16 cm (1/16 inch) angled perforations 633 in communication therewith.

The nozzle 640 of Figure 16 includes the first conical passageway portion 641, a second portion 644 comparable to the passageway portion 624 of the Figure 14 embodiment, and a pair of passageway portions 642, 646 each which are generally conical in shape and have four 0.16 cm (1/16 inch) angled perforations 643, 647, respectively extending outwardly therefrom.

Viewing the vacuum spun yarn illustrated in Figures 1 and 2, it will be seen that a fasciated yarn is provided consisting of staple fibres including core fibres and wrapper fibres. The wrapper fibres are predominantly individual fibres although there are some groups of wrapper fibres. The groups of wrapper fibres appear as non-uniform, non-consistent fibre groupings and provide a relatively smooth surface. The core fibres are essentially parallel with the wrapper fibres uniformly distributed therearound. The core fibres have the same dyeability as the wrapper fibres.

Another way that the yarn of Figures 1 and 2 can be described is a fasciated yarn having essentially parallel core staple fibres and having a uniform distribution of staple wrapper fibres around the core fibers. The wrapper fibers are wrapped at a helix angle of about 30^o (e.g. within the range of about 30-50^o), and about 20-30 percent of the fiber mass comprises wrapper fibers. The wrapped fibers are devoid of tucked or reverse wrapped fibers and are essentially devoid of auger or corkscrew appearing wrapped fibers, rather having a smooth appearance.

Comparing the vacuum spun yarn of Figures 1 and 2 to the conventional spun yarns of Figures 3 and 5 through 8, it will be seen that the vacuum spun yarn of Figures 1 and 2 has an appearance closest to that of the ring spun yarn of Figure 5.

Note that the core spun yarn of Figure 3 has core fibers which are parallel with a filament yarn twisted (a true twist) around the mass of yarn for strength. This is not a fasciated yarn.

The open end yarn of Figure 4 also has true twist, with a surface dotted with wrapper fibers loose around the mass. Again this is not a fasciated yarn.

The MJS air spun yarn of Figure 6 is the next closest to ring spun yarn (that is next closest with vacuum spun yarn being the closest) of the known spun yarns. The MJS yarn has fibers wrapped at approximately a 55^o angle showing a small amount of twist in the core fibers. The percentage of wrapped fibers is approximately 10 percent. The wrapper fibers are more or less in the form of individual fibers.

The Toray yarn of Figure 7 has wrapper fibers which are disposed at approximately a 45^o angle and appear to be buried deeper into the core fibers than for the other yarns, causing a corkscrew appearance. The surface fibers tend to be tangled in the fiber mass similar to Taslan yarns. Approximately 20 percent of the fibers are wrapped surface fibers. The auger or corkscrew look of the Toray yarn is vastly different than the smooth appearance of vacuum spun yarn.

The DREF II yarn of Figure 8 is friction spun yarn with true twist and without any surface wrapped fibers. This yarn is also not a fasciated yarn.

It is noted that the fasciated yarn can be made from 100 percent non-thermoplastic staple fibers. That is at least the predominant portion of the staple fibers forming the fasciated yarn can be selected from the group consisting of cotton, mohair, flax, ramie, silk, wool, rayon, and blends thereof. However the fasciated yarn is not restricted to non-thermoplastic fibers, but also can be produced from, or from blends of (with non-thermoplastic fibers) acrylic, polyester, and other fibers.

Note that vacuum spun yarn has many differences compared to other known fasciated yarns. Some properties of vacuum spun yarns that are not true of all other fasciated yarns are as follows: Vacuum spun yarn does not require thermoplastic fibres, the wrapped fibres can be the same as the core (not fused by heat), the yarns will dye the same since the molecular structure thereof is not changed (the core and surface fibres have the same dyeability), and the wrapped fibres are laid parallel and not looped over each other in a non-uniform pattern.

The apparatus and method described above provide a yarn suitable for making apparel fabric, comprising a fasciated yarn which has good strength and appearance properties, and most closely simulates ring spun yarn, yet which can be produced at much higher speed than ring spun yarn and with fewer steps. For instance in ring spinning long staple yarns, first the staple fibres are blended, gilled, combed, gilled four times, used to produce a roving, spun, wound, and then put to an end use. Vacuum spun yarn of the other hand, made from long staple fibres is produced as follows: the fibres are blended, gilled, combed, gilled three times, vacuum spun, and then put to the end use. Thus three less steps are used in vacuum spinning long staple fibres compared to ring spinning long staple fibres. In vacuum spinning short staple fibres, the same number of steps are used as for air jet spinning short staple fibres, namely blending, carding, drawing twice, spinning, and putting to an end use.

Claims

Apparatus for forming yarn from fibres (S), comprising an elongate rotary hollow shaft (30), a through passageway (31, 33) extending through the shaft (30) between a first end (21) and a second end (22) of the shaft (30), at least a portion of the surface of the shaft including perforations (40), means (26) for passing the fibres (S) through the passageway (31, 33) from the first end (21) to the second end (22), means (24) for rotating the shaft (30) and means (18) for applying a vacuum to the exterior of the shaft (18) towards the perforations (40), the passageway (31, 33) including a relatively enlarged cross-sectional area portion (31) adjacent the first end (21) of the passageway (33), whereby at least some of the fibres (S) are caused to extend outwardly and wrap around a core of fibres (S) as the core passes through the passageway (31, 33), the enlarged cross-sectional area portion (31) being generally conical in shape and being arranged so that the reduced cross-sectional area portion thereof faces towards the second end (22) of the passageway (33).
Apparatus according to Claim 1, characterised in that the conical portion (31) comprises a right circular cone, the centre of which is disposed in alignment with the first and second ends (21,22) and the perforations (40) of the shaft (20) are generally wedge-shaped in longitudinal section and extend through the wall of the shaft in the region of the conical portion (31).