GB2027758A

GB2027758A - Apparatus for Producing a Bound Yarn

Info

Publication number: GB2027758A
Application number: GB7926472A
Authority: GB
Original assignee: Schubert und Salzer Maschinenfabrik AG
Current assignee: Rieter Ingolstadt Spinnereimaschinenbau AG
Priority date: 1978-07-29
Filing date: 1979-07-30
Publication date: 1980-02-27
Also published as: DE2833326C2; DE2833326A1; CH638247A5; GB2027758B

Abstract

An apparatus for producing a bound yarn which consists of a sliver (S) round which a binding thread (U) has been wound, comprises a hollow spindle (5) which is mounted between a pair of delivery rollers (1, 2,) and a pair of draw-off rollers (3, 4) and a rotatable binding thread bobbin (7) which is arranged coaxially of the hollow spindle and is surrounded by a dished element (8). The apparatus is characterised in that this dished element (8) is closed off by a cover (80) which carries a guide tube (9) for the sliver (S) delivered to the hollow spindle (5) by the pair of delivery rollers (1, 2). The guide tube (9) and the hollow spindle (5) are in aligned relation. <IMAGE>

Description

SPECIFICATION Apparatus for Producing a Bound Yarn This invention relates to an apparatus for producing a bound yarn, which consists of a sliver around which there is wound a binding thread.

Such apparatus comprises a hollow spindle which is mounted between a pair of delivery rollers and a pair of draw-off rollers, and a rotating binding thread bobbin, which is arranged coaxially of the hollow spindle and is surrounded by a dished element.

An apparatus of the type defined above, intended for producing a bound yarn, is known from U.S.A. Patent Specification 4,018,042. The binding thread, in this case a filament, is wound round the core of a flanged bobbin, which prevents layers of thread from slipping off the bobbin; to this extend a flanged bobbin is particularly advantageous. Due to the rotation of the binding thread bobbin, which is arranged on the driven hollow spindle and is fixed for rotation with the latter, binding thread is wound round the sliver which is delivered by the pair of delivery rollers into the hollow spindle, and the finished, bound yarn is subsequently drawn out of the hollow spindle by the draw-off roller.When the binding thread is being drawn off the rotating flanged bobbin,-this draw-off process takes place with the formation of a thread balloon thread tension is created, so that the binding thread is placed, subjected to tension, round the sliver and strengthens the latter. The tension of the binding thread-the mean value of this tension depends on the speed of the bobbin body and on the fineness of the binding thread, and alters as a function of the shape of the binding thread bobbin-affects the yarn structure; consequently, this thread tension should not be too high, as prescribed in the abovecited earlier proposal.A reduction in the thread tension is achieved by the dished element, which rotates with the binding thread bobbin and serves as a "balloon" limiter, this dished element preventing free swinging movement of the thread "balloon".

It has been found to be a disadvantage that, in the couse of continuous operation after egress of the sliver from the pair of delivery rollers, fibres separate from the sliver, deposit on the rotating binding thread, and in this way adversely affect the production of the bound yarn. A false twist is imparted to the sliver by the thread tension, engaging the sliver, of the binding yarn; this false twist can be further increased by frictional contact of the sliver with the hollow spindle, and suffices to so strengthen the sliver between the outlet of the pair of delivery rollers and the inlet to the hollow spindle that breakages are avoided.

However, even this false twist effect does not completely prevent fibres separating from the sliver. Fibres can separate from the sliver, which has already been bound, and reach the inlet opening of the hollow spindle, where these fibres pass out of the hollow spindle.

The fibres which have become free can then reach the binding thread bobbin or the flange of the (preferably used) flanged bobbin and, when they strike against this flange, are thrown outwardly. However, the speed at which this occurs is relatively low in comparison with the speed of the rotating binding thread, so that the rotating thread "balloon" of the binding thread seizes the outwardly-slipping fibres. The fibres loop round the binding thread and are held, between the binding point and the greatest "balloon" diameter, on the thread "balloon" by the high centrifugal force of this thread balloon; a fibre tuft is finally formed in this area. At a high spindle speed this fibre tuft is dragged along in consequence of the high air resistance, that is to say the binding thread slides, at its draw-off speed, through the fibre tuft without pulling the latter with it.

Due to the high air resistance to which the binding thread is subjected due to the fibre tuft, and due to the increased weight in the balloon, there is a g'reater envelopment of the binding thread, which is in the process of running off, round the core of the bobbin, as a result of which the pulling force of the binding thread is increased. However, such an increase in the pulling force or in the tension of the binding thread is undesirable because, as mentioned above, such an increase affects the yarn structure and also the technological yarn properties, in particular the tearing force, and has a deleterious effect on the yarn quality.

Underlying the present invention is the general object of eliminating these drawbacks and of providing an apparatus which enables a qualitatively satisfactory binding yarn to be made.

According to the invention, in an apparatus of the type defined it is arranged that the dished element should be closed off by a cover, which carries a guide tube for the sliver delivered by the pair of delivery rollers into the hollow spindle, the guide tube and the hollow spindle overlapping each other.

In this way it is ensured that fibres which, after the sliver has left the pair of delivery rollers, become separated from the sliver, are held away from the binding thread, and cannot have an unfavourable effect on the tension of this binding thread or on the yarn quality. It is also ensured that, due to the overlap of the guide tube and hollow spindle, individual fibres which have become freed in the course of transference of the sliver from the guide tube into the hollow spindle cannot pass into the dished element and form a fibre tuft on the binding thread.It is also possible-if the dished element, which is closed off by the cover, and, hence, the guide tube rotates with the binding thread bobbin-to initiate the process of imparting a false twist to the sliver before the binding point or station by bringing the sliver into frictional contact with the guide tube. As the guide tube and the hollow spindle have the same speed as each other and are responsible, together with the binding thread which engages the sliver, for the false twist of the sliver, there is a reduction in the chance of fibres passing out between the guide tube and the hollow spindle. This effect is further reinforced if the inner wall of the guide tube is structured.

Replacement of the guide tube is rendered possible through the guide tube being releasably connected to the cover. Thus, the guide tube can be accommodated to the spinning parameters effective at any given time in respect of the length and inner diameter of this guide tube. In order to make it possible to accommodate the distance between the guide tube and the hollow spindle to the fineness of the binding thread to be processed, the guide tube is shiftably arranged in the cover. In order to prevent the depositing of dust, fibre fragments or the like on the upper part of the dished element, the side wall of the cover has openings. Conveniently, the cover consists of an upper part, which carries the guide tube, and of a lower part, which is mounted on the dished element, this said upper part and said lower part being connected to each other by strips.The depositing of dust on the strips is prevented by making the strips tapered.

Further features and details of the invention are hereinafter elucidated with reference to Figures 1 to 3, in which: Figure 1 illustrates a binding apparatus in longitudinal cross section; Figure 2 is a longitudinal cross section of a guide tube which projects into the hollow spindle; Figure 3 is a view, with partial longitudinal cross-sectioning, of a laterally-open cover, with guide tube.

A hollow spindle 5 is mounted vertically and rotatably in the machine frame 6 between a pair of delivery rollers 1, 2, and a pair of draw-off rollers 3, 4 (Figure 1). Mounted on, and fixed for rotation with, the hollow spindle 5 is a bobbin round the core of which is wound a binding thread U, this bobbin is hereinafter referred to below as the binding thread bobbin 7. Conveniently, the bobbin round which the binding thread U is wound-this binding thread U consisting of a filament, of a yarn, or of a twine-is constituted as a flanged bobbin 70, the flanges of which prevent the layers of thread from slipping off the bobbin core.

Further, a dished element 8 is fixed on the hollow spindle 5 and serves as a balloon limiter, this dished element 8 surrounding the binding thread bobbin 7 with a distance therebetween.

While the hollow spindle 5 is being driven, for example by means of a tangential belt 50, the dished element rotates with the hollow spindle 5 and with the binding thread bobbin 7. However, the dished element 8 may possibly be stationarily arranged. In this case the dished element 8 is, for example, fixed on the machine frame 6 or on the outer bearing ring (not shown) for the hollow spindle 5, this outer bearing ring being arranged in the machine frame 6.

The upper part of the dished element 8 is closed off by a cover 80, which carries a guide tube 9 for the sliver S leaving the pair of delivery rollers 1, 2. The cover 80 can be removed from the dished element 8 so as to allow access to the binding thread bobbin 7. The straight guide tube 9, which projects through the cover 80 into the dished element 8 extends, at a prolongation of the longitudinal axis of the hollow spindle, in the direction of the pair of delivery rollers 1, 2, and is secured to the cover 80, preferably by removable securing means (not shown), so that this guide tube 9 can be vertically shifted and can also be replaced. The length, the inner diameter, and the shape of the guide tube 9 may be accommodated to the existing spinning parameters, such as staple length and fineness of the fibres present in the sliver.The guide tube 9 may however be differently shaped,-for instance it may be curved. As fibres can become separated inside the guide tube 9 and the hollow spindle 5 from the sliver, and then pass, in the area between the guide tube 9 and the hollow spindle 5, into the dished element 8, the distance a between the guide tube 9 and the hollow spindle 5 is kept as small as possible, more specifically just large enough to enable the binding thread U to pass into the hollow spindle 5 without being obstructed by the guide tube 9.

In one particularly favourable embodiment the inner diameter d2 of the guide tube 9 is smaller than the inner diameter d1 of the hollow spindle (Figure 2). In this way it is possible for the guide tube 9 to project into the hollow spindle 5, so that both of them overlap and in this way prevent fibres which have worked loose from making their way out of the guide means into the interior of the dished element 8 and settling on the binding thread U. Such an overlap may possibly also be realised by arranging for the inner diameter of the guide tube 9 to be greater than the outer diameter of the hollow spindle 5. It may suffice merely to provide the increased inner diameter of the guide tube 9 in the vicinity of the overlap area. In this case it is not absolutely necessary for the guide tube 9 to project into the dished element 8.

Indeed, the arrangement may for example be such that the outlet opening of the guide tube 9 lies at the level of the lower edge of the cover 80, the hollow spindle 5 projecting into the guide tube.

Naturally, in this case, the distance necessary for ingress of the binding thread U into the hollow spindle 5 must be available between the guide tube 9 and the hollow spindle 5.

When the dished element 8 rotates together with the binding thread bobbin 7, the sliver S leaving the pair of delivery rollers 1, 2, comes into continuous frictional contact with the inner wall of the guide tube 9, as a result of which a false twist is imparted to the sliver S before the binding area; this false twist is propagated to the neck of the pair of delivery rollers 1, 2, and strengthens the sliver S. Individual fibres which have not become bonded, or which have only become insufficiently bonded, and separate from the sliver prior to entry into the guide tube 9, are prevented by the cover 80 which rotates together with the dished element 8, from reaching the area of the rotating binding thread U.Also, fibres which become separated from the sliver inside the guide tube 9 can only pass out into the interior of the dished element 8 with difficulty, or cannot pass out into the interior of the dished element 8 at all, owing to the small distance between the guide tube 9 and the hollow spindle 5 and due to the overlap of these elements 9 and 5. In this way the thread tension, and hence the yarn quality, remain unaffected by fibres which have worked their way loose. Also it is no longer necessary to accommodate the diameter of the hollow spindle 5 to the instantaneous yarn fineness, as the false twist initiated by the guide tube 9 suffices, in general, for ensuring a sufficiently good bond of the fibres between the pair of delivery rollers and the binding station.

In certain cases, for example when coarse fibres are being processed and in the manufacture of coarse yarns, in which comparatively frequent separation of fibres from the sliver is to be expected, it may be necessary to increase the false twist and, hence, the interlacement or bond of the fibres with one another. For this purpose the inner wall of the guide tube 9 is given a special structure; for example it may be provided with notches. In this way the separation of fibres from the sliver may be restricted, while fibres which have become loose in the above-described manner are prevented from having a harmful effect on the tension of the binding thread.

As mentioned above, the dished element 8 may also be stationarily secured, e.g. on the machine frame 6. In this case a false twist is imparted by the rotating hollow spindle 5 to the sliver S issuing from the pair of delivery rollers 1, 2. It is not possible completely to preclude the possibility of dust and short fibre fragments passing out into the dished element 8 and, when the dished element 8 rotates, settling in the form of a ring in the upper part of the dished element 8.

In the course of lengthy operation this accumulation of dust and fibres can lead to breakage of the binding thread. This is prevented by the provision of a cover which is laterally open.

Figure 3 illustrates such a cover 80, of which the side wall has cutaway portions or openings 81. In the embodiment illustrated, the upper part 801 of the cover 80, which carries the guide tube 9, is connected to the lower part 802, which rests on the dished element 8, by means of strips 803, so that dust and fibre fragments can pass to the outside through the openings 81 defined between the strips 803. Conveniently, the strips 803 are tapered, the tip of the taper pointing towards the centre of the cover 80. This prevents fibre dust and other particles which have become free, from settling on the strips 803. The illustrated construction of a laterallyopen cover may possibly be replaced by bores at the periphery of the cover.

Claims

1. Apparatus for producing a bound yarn, which consists of a sliver round which a binding thread has been wound, with a hollow spindle, which is mounted between a pair of delivery rollers and a pair of draw-off rollers, and with a rotatable binding thread bobbin which is arranged coaxially of the hollow spindle and is surrounded by a dished element, characterised in that the dished element is closed off by a cover, which carries a guide tube for the sliver delivered to the hollow spindle by a pair of delivery rollers; the guide tube and the hollow spindle overlapping each other.

2. Apparatus according to claim 1, characterised in that the inner wall of the guide tube is structured, and the guide tube rotates with the dished element.

3. Apparatus according to claim 1 or claim 2, characterised in that the inner diameter (d2) of the guide tube is smaller than the inner diameter (dt) of the hollow spindie.

4. Apparatus according to any of claims 1 to 3, characterised in that the guide tube is releasably connected to the cover.

5. Apparatus according to claim 4, characterised in that the guide tube is shiftably arranged in the cover.

6. Apparatus according to any of claims 1 to 5, characterised in that the side wall of the cover has openings.

7. Apparatus according to claim 6, characterised in that the cover consists of an upper part, which bears the guide tube, and of a lower part which is mounted on the dished element, the upper part and the lower part being connected to each other by strips.

8. Apparatus according to claim 7, characterised in that the strips are tapered.

9. Apparatus for producing a bound yarn substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.