GB2062023A

GB2062023A - Open-end spinning apparatus

Info

Publication number: GB2062023A
Application number: GB7936651A
Authority: GB
Original assignee: Platt Saco Lowell Ltd
Current assignee: Platt Saco Lowell Ltd
Priority date: 1978-10-26
Filing date: 1979-10-23
Publication date: 1981-05-20
Also published as: GB2062023B; JPS5944405B2; JPS5759328B2; KR830001434A; JPS57193527A; JPS56101919A; FR2439832A1; KR840000326B1; KR830001595B1

Abstract

An open-end spinning apparatus comprises an opening roller system 34 for feeding fibres in a feed duct 41 to the throat formed between the adjacent peripheral surfaces of two parallel drums 1 rotating in the same direction. Yarn formed at the throat, by frictional contact between the fed fibers and the surfaces, is withdrawn along the throat. The fibre feed duct is arranged to feed the fibres in a direction inclined to the yarn axis and with a component of motion opposite to the direction of yarn withdrawal. A suction opening in the duct in the wall facing away from the drums causes an additional airstream across the duct parallel to the yarn axis to turn the fibres to a direction nearer parallel to the yarn axis. One of the drums is perforated for suction through its surface, the other is imperforate and formed with a resilient surface of a rubber material. <IMAGE>

Description

SPECIFICATION Improvements relating to open end spinning machines This invention relates to apparatus for the open-end spinning of textile yarns, and particularly to an open-end spinning apparatus comprising at least one yarn formation surface, a fibre feed duct for conveying fibres onto the surface, means for moving the surface to twist the fibres deposited thereon to form a yarn and means for withdrawing the yarn transversely to the direction of motion of the surface.

In one known example of open-end spinning apparatus of this type the fibres are fed into a throat formed between the adjacent peripheral surfaces of two parallel drums rotating in the same direction. By frictional contact with the moving drum surfaces the fibres in the throat are twisted into a yarn which is then withdrawn transversely of the movement of the drum surfaces. In a further known example the fibres are fed onto a moving perforated belt where the fibres are maintained in a yarn formation zone defined by a suction nozzle positioned beneath the belt and are twisted into a yarn by the moving belt. The yarn is then withdrawn in a direction transverse to the direction of movement of the belt.

A problem that arises with open-end spinning apparatus of this type is the unsatisfactory deposit of the fibres in the region of the tail end of spun yarn for incorporation therein.

One example for achieving the most advantageous deposit of fibres is disclosed in British Patent No. 1,524,659. The apparatus disclosed in this patent comprises two closely spaced apart perforated suction drums which rotate in the same direction and define between them a throat into which the fibres are fed from fibre feeding means and formed into a yarn.

Disposed in the path of the fibres between the fibre feed means and the throat is a toothed disc arranged for rotation in a plane transverse to the direction of movement of the fibres. The fibres are, it is said; deflected by the teeth on the rotating disc so that they are orientated to lie in a direction parallel to the movement of the spun yarn.

A disadvantage of this solution is that some of the fibres wrap around the teeth so that they tend to be removed from the mainstream of fibres, which is unacceptable. With this solution it is not possible to locate the rotating disc close to the yarn formation zone because of the physical limitations imposed by the rotating drums. Thus after contact with the teeth the fibres would lose the parallel orientation before reaching the yarn formation zone. Furthermore, the provision of a rotating disc requires additional drive means, thereby complicating the apparatus and introducing a source of possible failure to the system.

In a further known proposal DE-OS 2809599 discloses a detailed open-end spinning system of this general type, but does not give particular reference to the problem of proper orientation of fibres within the yarn as it is spun.

According to a first aspect of the invention there is provided apparatus characterised in that the fibre feed duct if arranged to feed fibres directly onto the area from which the yarn is withdrawn and in a direction which is inclined to the direction of yarn withdrawal and with a component of motion opposite thereto.

According to a second aspect, the invention provides apparatus characterised in that there are provided means for developing an airstream in a portion of the feed duct adjacent the surface in a position to ceuse at least some of the fibres as they approach the surface to change to a direction more nearly approaching a direction parallel to the axis of the withdrawn yarn.

The invention is illustrated by way of example in the accompanying drawings in which: Figure 1 is a sectional plan view of an open-end spinning apparatus according to the invention, with the section taken along the line I-I in Figure 2; Figure 2 is a section along the line Il-Il in Figures 1 and 3; Figure 3 is a partial schematic side view of the apparatus of Figure 2 showing only the drive arrangements for the drums 1 and 2, and with the drum 1 removed for clarity; Figure 4 is a section along the line IV-lV in Figure 1; and Figure 5 is a partial plan view of the apparatus showing in more detail the opening roller arrangement.

The apparatus comprises a pair of parallel, closely spaced drums 1 and 2. The surface of the drum 1 includes a portion which is perforated as shown at the area 3, which is cross-hatched in Figure 4.

The drum 2 is formed of a metal core cylinder 4 on which is bonded a cylindrical sheel or coating 5 of a resilient material, preferably a natural or synthetic rubber such as polyurethane, adiprene or caprolactone. It has no perforations. The thickness of the shell is of the order of 2 mm and the hardness of the material lies in the range 40 to 90 Shore A and most advantageously 60 Shore A.

The peripheral surfaces of the drums 1, 2 define between them a gap which tapers towards a narrow throat at the point of closest approach.

The cylinder 4 of the roller 2 is carried upon ball bearings 6 for free rotation about a shaft 7 which supports the bearings 6. The shaft itself is rigidly supported in respective bores in a pair of arms 8, 9 which as shown in Figure 2 are pivotally mounted on bar 10, and about which the arms 8, 9 and thence the roller 2 can be pivoted to increase or decrease the gap between the rollers 1 and 2.

The roller 1 comprises the perforated cylindrical portion 3 and imperforate extensions 11 and 12 which act to give support and rigidity to the portion 3. Within the roller 1 is mounted a suction tube 13 which comprises an elongate cylinder forming a tight clearance, of the order of 1 or 2 thousands of an inch, with the roller such that the roller is free to rotate about the tube 1 3. The tube 13 includes a slot 14 adjacent the throat between the rollers 1 and 2 to communicate suction within the tube 13 to the throat as will be explained hereinafter.

The tube 13 is rigidly mounted at one end by insertion within a bore 14 formed in a support 15 fixed to a machine frame 16 against which the end of the tube 13 abuts. The bore 14 is opened out to form a cylindrical cavity 17 so as to provide a housing for a bearing 1 8 which rotatably supports one end of the perforated drum 1.

The other end of the tube 13 is closed and reduced in cross-section to provide a boss 19 on which is supported a bearing 20 for rotatably supporting a reduced diameter portion 21 at the end of the drum 1. The interior of the tube 13 communicates with a source of suction 22 which comprises a duct extending through the machine frame 16.

The drive for the drums 1 and 2 is derived from a motor (not shown) which is drivingly connected to one end of a countershaft 23 rotatably supported by a pair of bearings 24 mounted in a housing 25. The other end of the countershaft 23 supports on its end a timing belt pulley 28. A timing belt 27 wraps around the pulley 26 and around a timing belt pulley 28 which, as best seen in Figure 1, is supported at the end of the drum 2 by a spigot 29 extending into the interior of the cylinder 4 of the drum 2. A tension pulley 30 engages the timing belt 27 which can be adjusted so as to provide the correct driving tension in the belt for different sizes of pulleys 26 whereby different speed ratios of the drums can be obtained.

Also supported on the countershaft 23 at a position intermediate the pulley 26 and the housing 25 is a further timing belt pulley 31 mounted directly beneath a timing belt pulley 32 which is fixedly attached to the peripheral surface of the drum 1 at a position adjacent to the bearing 18. The pulleys 31 and 32 are drivingly connected by a timing belt 33.

The drive from the main motor (not shown) is transmitted to the countershaft 23 so as to cause rotation of the pulleys 26 and 31 in a direction such that their respective belts drive the drums 1,2 in the same direction, i.e. in an anti-clockwise direction as seen in Figure 2. The rotation of the drums 1 and 2 is such that the periphery of drum 2 provided with the coating 5 moves out of the throat towards the side adjacent to the fibre feed duct 41 and the peripheral surface of the drum 1 provided with the perforated portion 3 moves from the side adjacent the fibre feed duct 41 into the throat.

A fibre feed apparatus, generally indicated at 34, comprises a sliver feed roller 35, a feed pedal 36, and a beater 37 mounted on a shaft 38 for rotation within a housing 39. The housing 39 has an opening 40 to permit the ejection of impurities therethrough. This type of fibre feed apparatus 34 is well-known in open-end spinning systems of the spinning rotor type and an example is described in more detail in British Patent No. 1,368,886.

The fibres are conveyed from the fibre feed apparatus 34 to the throat formed between the peripheral surfaces of the drums 1, 2 by a fibre feed duct 41. The fibre feed duct 41 has a first duct portion 42 having a fibre inlet aperture in communication with a rectangular passage 43 provided in the housing and a second terminal duct portion or nozzle 44 which terminates in an elongate mouth 45 within the throat. The first duct portion 42 is of varying rectangular crosssection defined by two side walls 46, which gradually converge as the first duct portion 42 approaches the throat, and by a front wall 47 and a rear wall 48. The longitudinal axis of the first duct portion 17 is inclined at an angle of 20 to 450 and more preferably 250 to 300 with respect to the axis of the drums 1,2.

At the junction of the first and second duct portions 42, 44 the front wall 47 terminates in an air channel or duct 49 which communicates with the terminal duct portion 44 for a purpose to be later described. The duct 49 extends from the terminal duct portion 44 in a direction generally parallel to the axes of the drums 1,2 and is connected to a source of suction indicated schematically at 50. The walls of the first duct portion 47, 48 change direction abruptly to form walls 51, 52 of the terminal duct portion 44. The terminal duct portion 44 widens in the vicinity of the mouth 45 in that the rear wall 51 thereof extends from the entrance of the suction duct 53 to a position corresponding to one end of the slot 14 and in that the front wall 52 thereof is so angled as to extend to the other end of the slot 14.

Thus the mouth 45 extends as a narrow slot along substantially the whole length of the slot 14 so as to maximise the area of the mouth in communication with the slot 14. The end of the wall 52 is spaced further along the axis of the yarn than is the imaginary end of the wall 47 where it would intersect the mouth 45. For a feed duct having an angle of inclination of the first part 42 of 250, the best spacing of the imaginary point and the end of the wall 52 at the mouth has been found to be 25 mms.

The duct 49 has upper and lower walls 53, 54 respectively which diverge as the duct extends away from the interior of the fibre feed duct 41.

The lower walls 54 extends slightly upwardly as it approaches and conjoins with the front wall 52 to form a baffle. This baffle is disposed below the upper wall 53 at a position displaced from the junction between the walls 47 and 53.

The throat forms a yarn formation zone in which the fibres are twisted by rotation of the drums 1,2 into a yarn 'Y which is withdrawn axially of the drums 1, 2 along the throat by a pair of delivery rollers 55, located on the opposite side of the fibre feed duct 41 to that of the suction duct 49, and wound into a package 55a. The rotation wherein the drum 1 moves into the throat and the drum 2 moves out of the throat has been found to provide improved twisting efficiency relative to two perforated rollers with suction or one imperforate structured roller and one perforated suction roller. The drums give high twisting efficiency while allowing motion of the yarn axially without developing unacceptably high levels of tension. The direction of the rollers is important to give proper balance of the yarn in the throat.A yarn delivery tube 56 extends from a machine frame wall 57, in which it is fixedly mounted, to a position closely adjacent the ends of the drums 1,2.

In operation, a sliver S' is forwarded between the nip formed between the feed roller 35 and the feed pedal 36 to an opening and combing action effected by needles or teeth on the peripheral surface of the beater 37. The opened fibres are conveyed on the peripheral surface of the beater 37 to the entrance of the fibre feed passage 43 where they are removed from the beater 37.

Impurities are ejected through the opening 40. In this passage 43 the fibres are entrained in an airstream derived from the source of suction connected to the interior of the tube 13 by the duct 22. This source of suction communicates with the passage 43 through the slot 14, the perforated portion 3, the mouth 45 and the fibre feed duct 41. After passing through the passage 43 the fibres are conveyed by the airstream along the first duct portion 42 in which they lie generally in alignment with the direction of motion of the airstream i.e. at approximately 250 to the axes of the drums 1,2, and in a direction opposite to the direction of yarn withdrawal.

At the termination of the first duct portion 42 the fibres come under the influence of the suction derived through the suction duct 49. The influence of this suction causes an airstream to be developed in a direction substantially parallel to the axis of the yarn. This airstream is not disturbed by any additional airstreams introduced into the feed duct so that a uniform flow without turbulence is obtained. This airstream causes the total flow of air and at least some of the entrained fibres to change their direction of motion. The feed tube 41 feeds fibres, therefore, directly into the bottom of the throat, i.e. directly into the yarn formation zone and from where the yarn is withdrawn, with a direction which approaches a direction which is more nearly parallel to the axes of the drums 1, 2.The fact that the wall 52 is spaced further axially of the yarn than an imaginary extension of the wall 47 gives room for the fibres to turn and to be drawn downwards by the suction through the mouth 45. If however the spacing of the wall 52 along the axis is too great, then too great a turning effect is achieved and the proper effect lost. Thus there is a higher probability that fibres are incorporated into the tail end of the spun yarn 'Y' as they lie in alignment, or substantially in alignment, with the axis of the yarn 'Y'. The baffle formed by the walls 52 and 54 serves to prevent the airflow in the duct 49 from directly countering the airflow through the mouth 45 and hence to avoid removal of fibres from the yarn formation zone by the suction airstream created in the suction duct 49.The suction duct 49 communicates with the terminal duct portion 44 in the vicinity of the tail end of the yarn 'Y'. This ensures that the suction from the duct 49 will at least influence those fibres which will form the core section of the yarn so that they have a higher probability of lying substantially parallel to the axis of the yarn as they are incorporated therein. Of the fibres constituting the yarn 'Y', those forming the core make a major contribution to the strength of the yarn, and it is important that these should be incorporated in the yarn in a satisfactory manner.

It is also important to ensure that the suction forces emanating from the suction duct 49 and the suction slot 14 act on the fibres in a balanced relationship. The suction force from the duct 49 should not, of course, be of sufficient strength to completely overcome the effect of the suction force acting on the fibres from the slot 14 otherwise useable fibres will be extracted through the duct 49, but should be of a magnitude just sufficient to cause a redirection of the fibres so that they lie substantially or more nearly parallel to the axis of the yarn. In practice it has been found that of the order of 32 cfm drawing through the tube 1 3 and 10 cfm through the duct 49 provides a suitable balance.The duct 49 is arranged adjacent to the mouth 45 and the throat so as to act upon the fibres as close to the mouth as possible without interfering with the airstream through the mouth and thus removing fibres. It is believed that the fibres in the feed duct have a tendency to turn from the feed direction of 250 toward the vertical direction as they come into the direct influence of the suction through the slot 14 at the mouth 45. The creation of an additional air flow by the duct 49 across the mouth 45 opposes this tendency and acts to change the direction of the fibres so as to approach the wall 52 at an angle more nearly approaching a direction parallel to the yarn axis than they would otherwise do.

Although possibly less desirable, the fibre feed duct 41 could be inclined in a direction opposite to that shown in Figure 4. In such an arrangement the inclination of the longitudinal axis of the first duct portion will be 250 with respect to the axes of the drums 1, 2 and the fibre conveying airstream passing along this portion will convey the fibres in a direction corresponding to that of the spun yarn 'Y'. The suction duct 49 would communicate with the fibre feed duct 41 through that wall adjacent the delivery rollers so as to influence the fibres and cause them to be redirected so as to lie in a direction substantially parallel to the axis of the spun yarn.

Claims

1. Apparatus for open-end spinning yarn comprising at least one yarn formation surface, a fibre feed duct for conveying fibres onto the surface, means for moving the surface to twist the fibres deposited thereon to form a yarn, and means for withdrawing the yarn transversely to the direction of motion of the surface, wherein the fibre feed duct is arranged to feed fibres directly onto the area from which the yarn is withdrawn and in a direction which is inclined to the direction of yarn withdrawal and with a component of motion opposite thereto.

2. Apparatus according to claim 1, wherein the fibre feed duct is arranged to feed the fibres at an angle lying between 200 and 450 in a direction opposite to that of yarn withdrawal.

3. Apparatus according to claim 1 or 2, wherein the fibre feed duct is arranged to feed the fibres at an angle of lying between 250 and 300 in a direction opposite to that of yarn withdrawal.

4. Apparatus according to claim 1,2 or 3, wherein the fibre feed duct has side walls extending from one end adjacent fibre feed means to an elongate mouth adjacent the surface, and at least one of the side walls includes a change in direction such that the duct opens to form a nozzle adjacent the elongate mouth.

5. Apparatus according to claim 4, wherein prior to the change in direction the side walls are substantially parallel.

6. Apparatus according to any preceding claim, including bodies defining first and second surfaces, the bodies being arranged such that the surfaces define a space between them which tapers toward an elongate throat at the area of closest approach of the surfaces, wherein the withdrawing means withdraws the yarn from the throat.

7. Apparatus according to claim 6, wherein the first and second surfaces comprise the-external surfaces of bodies of revolution.

8. Apparatus according to claim 6 or 7, wherein the first surface is perforated and there is provided a suction source for developing an airstream through the first surface, and the second surface is imperforate.

9. Apparatus according to claim 8, wherein the first surface is arranged to move in a direction from a position adjacent the fibre feed duct into the throat and the second surface is arranged to move in a direction out of the throat toward the fibre feed duct.

10. Apparatus according to claim 9, wherein the second surface is formed by a resilient - material.

11. Apparatus according to claim 10, wherein the resilient material is provided by a natural or synthetic rubber.

12. Apparatus according to claim 10 or 11, wherein the material has a hardness within the range 40 to 90 Shore A.

13. Apparatus according to claim 12, wherein the material has a hardness of 60 Shore A.