GB1574534A

GB1574534A - Open-end spinning

Info

Publication number: GB1574534A
Application number: GB1191279A
Authority: GB
Original assignee: Barmag Barmer Maschinenfabrik AG
Current assignee: Oerlikon Barmag AG
Priority date: 1976-03-27
Filing date: 1977-03-25
Publication date: 1980-09-10
Also published as: JPS6330411B2; GB1574533A; JPS61179324A; IT1078000B; JPS6330412B2; GB1574532A; GB1574531A; JPS52140640A; DE2613263A1; CS215122B2; CS209436B2; JPS61179325A; CS215121B2; BR7701876A; JPS6113005B2; DE2613263B2

Description

PATENT SPECIFICATION ( 11) 1574534

e ( 21) Application No 11912/79 ( 22) Filed 25 March 1977 ( 62) Divided out of No1 574 531 ( 19) ( 31) Convention Application No 2 613 263 a ( 32) Filed 27 March 1976 in o ( 33) Fed Rep of Germany (DE) ( 44) Complete Specification published 10 Sept 1980 ( 51) INT CL 3 DOH 1/12 ( 52) Index at acceptance Di D AEX ( 54) OPEN-END SPINNING ( 71) We, BARMAG BARMER MASCHINENFABRIK AKTIENGESELLSCHAFT, a body corporate organised under the laws of the Federal Republic of Germany of Remscheid-Lennep, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly 5

described in and by the following statement:-

This invention relates to a method of spinning fibres to form a yarn.

According to the invention there is provided a method for the open end spinning of fibres to form a yarn between two surfaces moving in opposite directions, at least one of which surfaces is penetrated by an air current within a 10 defined area, the line of yarn formation being determined by a boundary line of the said area, wherein the fibres are fed to that line of yarn formation and wherein a continuous filament is supplied as a core filament on the line of yarn formation.

The invention also provides an apparatus for spinning fibres to form a yarn, comprising two air permeable surfaces movable in opposite direction, between 15 which surfaces the yarn is formed from discrete fibres fed to said surfaces, air suction devices on both sides of the moving surfaces which are remote from the yarn, and feeding means for feeding a yarn on the line of yarn formation into the region of fibre feed.

The moments of torsion exerted on the fibres by the apparatus of the invention 20 should preferably be relatively small and the apparatus should not be used in all cases of very thick yarns or high twists for producing the entire moment of torsion required for twisting the yarn In the case of such yarns additional twisting devices are therefore advantageously employed.

The invention will now be described with reference to the accompanying 25 drawings, in which:

Figure 1 is an overall view of the spinning process used as part of the present invention; Figure 2 is a sectional view of one embodiment of the process of Figure 1 in which the fibres are fed in from both sides; 30 Figure 2 a is a similar view of another embodiment; Figure 3 is a plan view of one form of a spinning process forming part of the present invention and in which a delivery action is exerted on the yarn; Figure 4 and Figure 4 a are representations of an embodiment of a spinning apparatus which uses the same principle as Figure 3; 35 Figure 5 is a perspective view of an embodiment of spinning apparatus according to the present invention and using a needle; Figure 6 is a perspective view of a spinning apparatus with a fibre feed device; Figure 6 a is a section through a spinning apparatus of Figure 6; and Figure 6 b shows a modified fibre feed device 40 Figure 1 shows schematically sieve belts 1 and 2 which move in opposite directions 11 and 12 Air currents 3 and 4 which pass through the sieve belts are produced by air supply means 13 and 14 The individual fibres 5 are delivered to one or both sieve belts Consider fibres which are first pressed against the sieve belt 2 by the air current 3 When these fibres enter the zone of the air current 4, they are 45 pressed against the sieve belt I by this current Since the belt I moves in the opposite direction to belt 2, these fibres are then carried back into the region of the first air current This circular motion causes the fibres to be twisted into a yarn 8.

The vectors of motion of the sieve belts 1 and 2 and of the air currents 3 and 4, taken together, encircle the line of yarn formation 9 in the same sense, thereby ensuring that the yarn 8 has a stable position on the line of yarn formation 9 The resulting yarn 10 is continuously pulled out of the zone between the surfaces of the sieves by winding devices (not shown).

The apparatus shown in Figure 2 comprises cylindrical sieve drums 1 and 2 5 which rotate in the same sense so that their surfaces move in opposite directions in the region of the line of yarn formation 9 On both sides of this line, suction devices 13 and 14 are arranged in their interior of the drums 1 and 2 respectively Each of these suction devices produces an air current 3 or 4 penetrating the respective sieve drum 10 The individual fibres are fed to the apparatus by a fibre feed device 6 or a fibre feed device 7 or both The fibre feed devices 6 and 7 are in the form of channels each ending in a curved plate which terminates adjacent a respective one of the sieve drums I and 2 Transport of the individual fibres in the fibre feed devices can be effected by an injector 15 Each of the fibre feed devices 6 and 7 may have a 15 carding roller of known construction arranged in front of it.

The individual fibres which have been transferred to the sieve drums 1 and 2 in the region of the air currents 3 and 4 by the fibre feed devices 6 and 7 are pressed against the drum surfaces by the air currents and carried into the zone of the line of yarn formation 9 The open ends of the suction devices overlap only slightly in the 20 region of this line 9.

The directions of the vectors of movement of the drums indicated in Figure 2 and the directions of the air currents combine to convert the individual fibres into a yarn along the line of yarn formation 9 The yarn formed along the line 9 is removed from the spinning zone, for example by means of a winding device, and 25 may subsequently be subjected to further twisting by means of a suitable twisting device, optionally after the spinning device, to impart the desired twist This twisting device may, for example, comprise three shafts rotating in the same sense and arranged at the corners of an isosceles triangle Friction discs are mounted in the sequence of their sense of rotation on these shafts, the discs overlapping at the 30 centre of the isosceles triangle The yarn is passed through the centre of this triangle and the friction discs both twist and transport the yarn.

The narrowest gap between the sieve drums 1 and 2, which lies in the plane containing the axes of the sieve drums, is approximately equal to the diameter of the yarn which is to be formed, but at the yarn outlet it is preferably slightly smaller 35 and in the region of the fibre inlet it is about two to three times greater than the diameter of the yarn to be formed For the manufacture of cotton yarn Nm 10, the preferred measurements of the narrowest gap are 0 1 mm in the region of the yarn outlet and 0 5 mm in the region of the fibre inlet For a cotton yarn Nm 20, the distance between the sieve rollers is preferably between 0 2 mm and 0 8 mm 40 Fig 2 a shows an apparatus similar to that of Fig 2 but in Fig 2 a fibres are supplied only through the fibre feed channel 6 It should be noted, however, that a second feed channel could also be provided in this case, as in Fig 2 A particular feature of the apparatus shown in Fig 2 a is that the opening of a suction device 13 is arranged in front of the plane connecting the axis of the two rollers 1 and 2 An 45 edge 16 of the opening, which determines the position of the line of yarn formation, is situated in front of the said plane, based on the direction of movement of the roller I which carries the fibres into the nip, by a distance equal to up to 10 times the diameter of the yarn Another feature of the arrangement of Fig 2 a is that the area defined by the opening of a suction device 14 in the roller 2 slightly overlaps 50 the area defined by the opening of the suction device 13 The distance between the edge 16 of the opening of the suction device 13 and an edge 17 of the opening of the suction device 14 in the region of overlap is equal to up to 10 yarn diameters This arrangement of the openings of the suction devices ensures that the line of yarn formation will be situated before the narrowest part of the nip This is 55 advantageous, not only for stabilizing the line of yarn formation but also for increasing the moment of torsion to be introduced.

The principle of combined twisting and transport of the yarn is illustrated in Figure 3 This shows the sieve belts 1 and 2 moving in parallel planes in the directions 11 and 12 The distance between the sieve belts is adapted to the 60 diameter of the yarn The suction devices 13 and 14 are arranged on the two sides of the line of yarn formation 9, optionally with slight overlapping of their openings.

The maximum width of the overlap is ten times the diameter of the yarn The diameter refers, as before, to the completely twisted yarn, and is calculated according to the following formula: 65 1,574,534 d(mm) = 1 12838 \/y (g/cm') x Nm% wherein y is the specific gravity and Nm (metric number) the fineness of the yarn, measured in metres per gram The individual fibres 5 are fed on to the belt 2 and may in addition be fed on to the belt I, and they are forced against the belts by the suction devices The yarns are then twisted on the principle already described 5 above.

At the same time, the sieve belts 1 and 2 have a component of movement in the direction of transport Viewed in top plane view, the sieve belts intersect at an angle 2 a The edges 16 and 17 of the openings of the suction devices 13 and 14, which edges define the line of yarn formation 9, are arranged on the bisector of this angle 10 2 cr or with a slight shift parallel thereto, so that the openings overlap This shift from the bisector of the angle may also be up to l Od, where "d" is the yarn diameter It should be mentioned that the air currents produced by the suction devices 13 and 14 may also have a component of movement in the direction of transport is The principle shown by Fig 3 can be realised in practice by the sieve drums of Fig 4, which are formed as hyperboloids 31 and 32 These hyperboloids are so arranged that their axes lie in parallel planes or that each of them has a generating straight line parallel to the line of yarn formation 9 This means that if the two axes are projected on a plane, the angle between them is twice the angle A 3 at which each 20 of the generating straight lines intersects its hyperboloid axis The vectors of movement 11 and 12 of the surface velocities of the circumferential surfaces of the hyperboloids in the narrowest gap formed between the two parallel generating straight lines intersect at an angle 2 a, which had already been defined.

The hyperboloids are so arranged that the narrowest gap between the adjacent 25 generating straight line is substantially rectangular The hyperboloid 31 is displaceable on the support 22 by means of a mounting 21 and is pivotal about an axis 24 It is therefore possible to adjust the width of the gap and/or to set the hyperboloid 31 at such an angle of inclination that the narrowest gap tapers towards the yarn outlet The frictional forces exerted by the sieve drums on the 30 fibres which are in the process of being compressed to a yarn consequently increase with progressive compression of the fibres Excessive moments of torsion and forces of tension liable to tear the yarn are thereby prevented from acting on the yarn At the same time, the tapering of the gap towards the yarn outlet ensures that sufficient torsion can be exerted to produce the required twist on the yarn leaving 35 the spinning device The dimensions of the narrowest gap are adjusted so that in the region where the fibres 20 are introduced the gap is twice as great whilst in the region of the yarn outlet it is smaller than the yarn diameter.

The drums 31 and 32 are driven in the directions 11 and 12 by drive motors 18 and 19 The suction devices 13 and 14 are situated on the insides of these drums, 40 and the openings of the suction devices extend over part of the internal circumference of the drums 31 and 32 and end shortly before, on or behind the line of yarn formation 8 Slight overlapping is again preferred, the area of overlap being situated before the narrowest gap, on the fibre feed side The fibre feed device (not shown in Fig 4) consists of a channel extending into the narrowest gap between 45 the drums 31 and 32 and having an opening in the form of a slit which extends over at least part of the length of the gap The completely formed yarn is drawn of by winding devices 23 at a draw-off rate of Va, optionally via a delivery mechanism.

In operation, the surface velocity of the drums is carefully adjusted to the 50 required twist and to the required yarn draw-off rate, and at the same time a compromise must be reached to allow for the amount of yarn tension which can be tolerated The draw-off rate is particularly limited by the fact that the yarn must not be exposed to excessive tension but at the same time it must not become slack.

The desired value Am depends on the envisaged use of the yarn 55 Experiments carried out with an apparatus described above having two slightly overlapping suction devices provided the following results:

1,574,534 4 1,574,534 4 Two hyperboloids maximum diameter: 85 mm Width of gap: 0 3 mm Overlap of suction devices 0 9 mm Angle of intersection of the vectors 5 of movement 2 a 1400 Yarn: Cotton, nominal staple 28 mm y= 1 54 g cm 3 Nm 24 m gr a metric = metric twist multiplier = 120 (ta is mainly a practical coefficient 10 specific to the particular application of the yarn, used for calculating the twist T of the yarn according to the formula T =a V Nm) Am is obtained from the particular use of the yarn Experience has shown a suitable value to be between 100 and 150.

Draw-off rate V, = 300 m/min 15 The factor varied in the experiment was the speed of rotation of the hyperboloids (u in m/min) This was done in such a manner that both hyperboloids had the same peripheral velocity at the point of yarn outlet The properties measured were the yarn tension (P, measured in ponds) at which the yarn was drawn from the apparatus, the twist per meter value (T, measured in twists per 20 metre) (T/m) actually achieved in the finished yarn, and the breaking length (Km), and they were calculated within the optimum ranges determined by the following formulae:

4.25 X 10-3 Xa x Va <u < 0 95 Va J 7 x sin a cos a as the wider range and 25 4.25 x 10-3 x am x Va x sin a + Va x cos a <u < 0 85 x Va VT cos a as the narrower range.

It was found that advantageous surface velocities u could be obtained within the following ranges:

132 m/min < 220 m/min <u < 746 m/min < 833 m/min 30 The experimental results are shown in the following Table; u(m/min) 100 200 400 600 800 900 P (p) 55 32 28 22 19 15 7 T ( 1/m) 375 505 630 680 730 795 BREAKING LENGTH 5 7 9 2 11 8 11 2 10 2 8 4 (km) a (metric) 76 5 103 128 6 138 149 162 The experimental results show that excessively high circumferential velocities and excessively high twist reduce the strength of the yarn Both these factors are deleterious for further processing In the region of the lower limit, on the other hand, the twists produced were so low that sufficient strength could not be 5 obtained.

The circumferential surfaces of the hyperboloids could, for example, be cut off in the normal planes along the lines 36 and 37 to produce an asymmetric structure.

This would be advantageous in cases where no tension was to be exerted on the resulting yarn 10 Fig 4 a shows a spinning apparatus similar to that of Fig 4 In Fig 4 a beadings 34 and 35 are placed on the end faces of the hyperboloid sieve drums on the outlet sides These beadings serve to grip the yarn which is already fully twisted at this stage In the region of the line of yarn formation, the hyperboloid sieve drums have a component of movement which causes twisting and another component of 15 movement which transports the resulting yarn and the individual fibres The transporting action is assisted by the beadings 34 and 35.

Such additional increase in the torque may be advantageous when a high torque is required to produce the necessary twist, as in the case of coarse fibres or a very high twist In these cases, an additional false twister 33 may also be provided 20 downstream of the spinning device.

It should also be mentioned with reference to Figure 2 that the fibres may be supplied either from the fibre feed device 6 or from the fibre feed device 7 or from both By supplying fibres from both feed devices 6 and 7 it is possible to produce mixed fibre yarns if fibres from one source are supplied through the fibre feed 25 device 6 and fibres from another source are supplied through the fibre feed device 7 The spinning apparatus represented in Figure 2 can therefore be used for both mixing and spinning individual fibres The fibre feed devices 6 and 7 may be staggered in relation to the line of yarn formation or additional fibre feed devices may be provided behind the devices 6 and 7 In this way, it is possible to spin yarn 30 having concentric layers of fibres of different types.

In the present invention the yarn is produced with a core formed from a continuous filament for example a continuous synthetic filament supplied from above on the line of yarn formulation 9 and passing between the surfaces Thus, a yarn is spun in which the core is made up of a continuous filament and the 35 sheath is of staple fibres The continuous filament is advantageously a textured filament with a three-dimensional crimp of the kind obtained, for example, by false twist texturing or air jet texturing.

In applying the invention to thick yarns and particularly thick yarns which are to be highly twisted, it has been found that the twist is not uniform over the cross 40 section of the yarn It has been found that the more internally situated filaments of the sliver have a smaller number of twists per metre than the more externally situated filaments To achieve uniform twisting across the section of the fibre even in the case of thick yarns, an additional torque may be introduced into the yarn by means of a rotating needle In Figure 5, which is otherwise similar to Figure 1, the 45 yarn 10 which has just been formed is continuously pulled out of the zone between the sieve surfaces 1 and 2 on one side of the sieve belts by winding devices (not shown) A needle 123 rotatably mounted in bearings 124 and 125 is situated on the other side of the apparatus The needle is driven by a motor 127 via a belt 128 and a pulley 126 in the direction in which the vectors of movement of the surfaces 1 and 2 50 and of the air current 3 and 4 encircle the line of yarn formation 9 The needle can 1,574,534 be shifted axially (this is not shown in the figure) so that it can dip to varying extents into the region in which the fibres 5 are brought to the line of yarn formation 9.

Experiments have shown that it is most effective to dip the needle into the yarn to a depth of about 30 mm In these experiments, the diameter of the needle was 1 5 mm and the needle tapered to a cone at its outer end over a length of about 10 mm The 5 speed of rotation of the needle was 60,000 revs/min A twist of 600 turns per metre could be achieved under these conditions The yarn draw-off rate was 100 m/min.

It should be noted that the needle may also advantageously be mounted in two pairs of rotatable support rollers at least one of which is driven, the needle being held in the nip of each pair of support rollers by magnetic forces 10 The needle 23 is, as shown in the drawing, and a core yarn 30 is supplied through the needle 23 By being supplied inside the needle, this yarn forms the core of the complete yarn to be formed, and as such has a major influence in the textile properties, particularly the strength and elongation of the completed yarn It should be mentioned here that the needle could be used with all the embodiments 15 of the invention described in this specification.

Figs 6 and 6 a illustrate a spinning apparatus having a fibre feed device 45 The spinning apparatus comprises cylindrical rollers 41 and 42 The circumferential surfaces of the cylindrical rollers are perforated The rollers are both driven to rotate in the same sense The rollers contain air suction devices, of which the 20 suction pipe connections 43 and 44 are shown in Fig 6 The fibre feed device comprises a housing which, in the representation in Fig 6 has been cut in a tangential plane This housing is placed against the roller 41 in the narrowest gap between the rollers 41 and 42 A delivery roller 47 and a carding roller 48 are rotatably mounted in the housing of the fibre feed device and driven by motors and 25 transmissions not shown in the drawing.

The delivery roller 47 pulls a yarn 46 into the fibre feed device and into the region of the circumference of the carding roller 48 The carding roller 48 is provided with teeth 53 on its circumferential surface The teeth 53 serve to separate the individual fibres of the yarn 46 and carry them over the circumference of the 30 carding roller to a channel inlet slot 51 The individual fibres are thrown into the inlet slot 51 by the centrifugal force and by the air current from an injector 49 which produces a vacuum in the channel inlet slot 51 Inside the inlet slot 51, these individual fibres are aligned substantially parallel to the axis of the carding roller.

The fibre feed channel becomes narrower both in the direction parallel to the axis 35 of the carding roller and in its cross-section The mouth 52 of the fibre feed channel is therefore situated parallel to the gap between the two rollers 41 and 42 and has length which is adjusted depending on the staple length The length of the mouth 52 is at least one third of the air permeable length of the rollers 41 and 42 The mouth 52 is only a few millimetres (I to 5 mm) wide Due to the fact that the cross-section 40 changes its form from the inlet slot 51 to the mouth 52 and diminishes in crosssectional area and due to the effect of the air currents from the injector 49, the individual fibres are turned and accelerated so that they are orientated to lie substantially in the same plane as the line of yarn formation and encounter this line, spaced apart from each other, at an angle of less than 300 The fibres are then 45 twisted together to produce the finished yarn 10 It should be mentioned that additional air channels may open into the fibre feed channel between the inlet slot 51 and the mouth 52 These air channels are so arranged that they reinforce the vacuum in the inlet slot 51, and favour the accleration separation, turning and orientation of the fibres in the manner described above 50 Fig 6 a also shows that the fibre feed channel has ribs 54 fanning out from the channel inlet slot 51 The ribs merge with the wall in gentle transitions, (see section) and low enough not to touch the opposite wall or opposite ribs The ribs have the effect of causing the fibres to lie in a plane parallel to the line of yarn formation In the end region 55 of the mouth 52, the plane in which the mouth lies is not parallel 55 to the plane of the narrowest gap between the rollers 41 and 42 but at an angle thereto of 20 This enables the air current produced in the fibre feed channel to escape against the direction of movement of the yarn 10 at the narrowest gap The individual fibres are thereby stretched and orientated The means for feeding a continuous filament to form the yarn core are not shown in Fig 6 a but would be 60 present.

If it is desired to use the apparatus of Fig 6 a to spin a yarn having concentric layers of fibres surrounding the core yarn, this can be done by adding an additional fibre feed device (indicated in dashed lines in Fig 6 a) to feed the outer layer, the Vh inner layer being fed by the feed device indicated in solid lines 65 1,574,534 Fig 6 b shows another embodiment of the fibre feed device, which has the advantage of promoting the orientation of the individual fibres parallel to each other and to the line of yarn formation and of promoting the stretching of the fibres The structure of the fibre feed devices is similar to that shown in Fig 6 a except that the mouth 52 of the channel is shifted by a considerable distance from 5 the inlet slot 51 in the direction of yarn formation The rear boundary 56 of the feed channel should make an angle E or less than 600 with the line of yarn formation while the front boundary 55 makes an angle a of less than 450 with the line of yarn formation.

Attention is drawn to our co-pending application No 12695/77 (Serial No 10 1,574,531) from which the present application is divided and to our copending application No 7930910 (Serial No 1,574,532) which is divided from application 12695/77 (Serial No 1,574,531) which include in their specification material common to this application.

Claims

is WHAT WE CLAIM IS: 15

1 A method for the open end spinning of fibres to form a yarn between two surfaces moving in opposite direction, at least one of which surfaces is penetrated by an aircurrent within a defined area, the line of yarn formation being determined by a boundary line of the said area, wherein the fibres are fed to that line of yarn formation and wherein a continuous filament is supplied as a core filamenton the 20 line of yarn formation.

2 A method according to Claim 1, wherein the core filament is threedimensionally crimped.

3 A method according to either preceding claim wherein in the region of fibre feed, the distance between the surfaces at the line of yarn formation is not smaller 25 than the thickness of the yarn which is to be formed.

4 A method according to any preceding claim, wherein the distance between the surfaces diminishes towards the yarn outlet along the line of yarn formation.

A method according to any preceding claim, wherein the distance between the surfaces at the yarn outlet is smaller than the diameter of the yarn being 30 produced.

6 A method according to any preceding claim, wherein the distance between the surfaces in the region of the fibre feed is more than twice the yarn diameter.

7 A method according to any preceding claim, wherein the surfaces are cylindrical 35 8 A method according to any preceding claim, wherein the fibres are supplied in two parts one from each side of a plane perpendicular to the said surfaces at the line of yarn formation.

9 A method according to claim 8, wherein the two parts each consist of fibres which differ from one another in at least one property 40 A method according to any preceding claim, wherein a plurality of fibre feed means is provided in the direction of the line of yarn formation over the range of operation of the surfaces.

11 A method as claimed in any preceding claim wherein the yarn being formed is additionally driven by a needle in the sense of rotation of the yarn 45 12 A method according to claim 11, wherein the core yarn is carried into the axis of twist at constant velocity through a concentric longitudinal bore in the needle.

13 An apparatus for spinning fibres to form a yarn, comprising two air permeable surfaces movable in opposite directions, between which surfaces the 50 yarn is formed from discrete fibres fed to said surface, air suction devices on both sides of the moving surfaces which are remote from the yarn, and feeding means for feeding a yarn on the line of yarn formation into the region of fibre feed.

14 An apparatus according to claim 13, wherein the moving surfaces are perforated surfaces of bodies of rotation, a suction device being arranged in each of 55 the bodies of rotation, the mouth of each suction device extending over part of the internal circumference and in the direction of the said line.

An apparatus according to claim 14, when in use, wherein the mouths of the suction devices overlap by a width of up to ten times the yarn diameter.

16 An apparatus according to claim 15, when in use, wherein the area of 60 overlap, viewed in the direction of fibre feed, is arranged in front of the narrowest gap.

17 An apparatus according to claim 16, when in use, wherein the area of 1,574,534 overlap is arranged in front of the narrowest gap by an amount equal to ten times the yarn diameter.

18 An apparatus according to any one of claims 14 to 17, wherein the axial distance and/or the position of the axes of the bodies of rotation is adjustable.

19 An apparatus according to any one of claims 14 to 18, wherein the axes of 5 the bodies of rotation are arranged to cross each other in such a manner that the narrowest gap diminishes towards the yarn outlet.

An apparatus according to any one of claims 14 to 19, wherein the diameter of the bodies or rotation continuously decreases towards the yarn outlet.

21 An apparatus according to any one of claims 13 to 20, wherein a respective 10 fibre feed device is arranged on each side of a plane perpendicular to the said surfaces at the line of yarn formation.

22 An apparatus according to any one of claims 13 to 20, wherein a plurality of fibre feed devices is arranged along the line of yarn formation.

23 An apparatus according to any one of claims 13 to 21, comprising a needle 15 which is drivable in the sense of yarn twisting by a motor, the needle being mounted in such a manner that its axis lies on the line of yarn formation and its tip extends into the region of the fibre feed.

24 An apparatus according to claim 23, wherein the needle is hollow and means are provided for supplying the core yarn through the needle 20 An apparatus according to any one of claims 13 to 24, wherein to feed fibres to the yarn formation line, a feed device is provided which comprises a housing with a cylindrical chamber whose axis, viewed in normal projection, is perpendicular to the axes of the bodies of rotation and in which a rotatably driven carding roller is mounted, a channel for introducing a card sliver which channel 25 opens into the chamber, a fibre feed channel extending substantially from the carding roller to the narrowest gap between the bodies of rotation and having a rectangular fibre inlet slot which connects the chamber with the fibre feed channel, and the long side of which extends along the axial length of the carding roller, the said fibre feed channel having an opening the width of which is substantially equal 30 to the width of the narrowest gap and the length of which is at least one third of the axial length of the air permeable wall of the bodies of rotation and the opening plane of which is inclined to the narrowest gap at an angle of between 0 and 200 towards the yarn outlet and means for producing a vacuum in the fibre inlet slot and for producing an air current from the fibre inlet slot to the mouth the surface 35 area of the cross section of the fibre feed channel diminishing between the fibre inlet slot and the mouth r 26 An apparatus according to claim 25, wherein ribs are arranged in a fan formation in the fibre feed channel on at least one of the boundary surfaces which extend from the broad side of the fibre inlet slot to the long side of the mouth, the 40 height of the said ribs being less than the width of the mouth.

27 An apparatus according to claim 25 or 26, wherein the front boundary of the fibre feed channel makes an angle of less than 450, and the rear boundary makes an angle less than 600, with the line of yarn formation.

28 An apparatus according to any one of claims 13 to 27, with a twister 45 arranged downstream of the apparatus.

29 An apparatus according to claim 28, wherein the twister is adapted to impart a component of movement in the direction of yarn delivery.

ELKINGTON AND FIFE, Chartered Patent Agents, High Holborn House, 52/54 High Holborn, London WCIV 65 H.

Agents for the Applicants.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1980.

Published by the Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.

8 1,574,534