WO1994003662A1 - Device for spinning a sliver - Google Patents

Abstract

The invention pertains to a device for spinning a sliver with a drafting arrangement and a pneumatic twisting device directly following the drafting arrangement, consisting of an injector part (1) and a twist part (2) connecting with it with clearance. The inside diameter of the twist part (2) is extended in shoulder form. Immediately after the shoulder-like extension of the inside diameter, an air-admission drill hole (20, 21) leads into the interior (23) of the twist part (2).

Description

Device for spinning a sliver

The invention relates to a device for spinning a sliver according to the preamble of patent claim 1.

A device for nozzle spinning is known from DE 3541219 AI. This device consists of an injector part and a swirl part adjoining it. The injector and swirl part are arranged directly after a drafting system for drawing a fiber sliver. A good yarn is produced in such a device, but the winding of the yarn core with edge fibers is not entirely satisfactory.

EP-A-418 694 shows a nozzle construction which, by means of an insert, creates a "shoulder" in the thread passage, with air inlet bores opening into the passage after the shoulder (viewed in the direction of passage). This construction also represents a step forward, but it is not the optimal solution.

EP-A-449 073 and EP-A-450 371 show drafting arrangements which are suitable for nozzle spinning. .

To optimize the system, it is important to keep the functions of the different elements as separate as possible and to consider each one separately. Viewed in this way, an optimal nozzle spinning system consists of three essential elements, namely:

a device (for example a drafting system) which, in particular, takes on the task of making drawn fibers available over a predetermined "delivery width" (see the aforementioned DE-A-3541219) a twist generator which generates a false twist in the fiber structure in such a way that a wrongly twisted core and projecting edge fibers arise, and

- An injector part, which must be arranged between the drafting device and the swirl device in order to loop the edge fibers around the core.

The object of the present invention is therefore to design the above-mentioned elements in such a way that each can perform its subtask as optimally as possible without interfering with another element of the system in fulfilling its task.

According to the invention, this object is achieved by the features of claim 1. The sliver is drawn and fanned out in the drafting system and in this state first reaches the injector part. Edge fibers are sucked in here and placed on the yarn core which has been rotated incorrectly by the twist action of the twist part. In the swirl part, the passage opening for the sliver is initially narrow and then widens in a shoulder shape. Immediately after the shoulder-shaped expansion, an air inlet hole opens into the interior of the swirl part. In the area of the air inlet bore, the sliver does not lie against the inner wall of the swirl part. The air jet that enters the interior of the swirl part through the air inlet bore thus strikes the fiber structure, which in this area is not guided laterally through the inner wall of the swirl part. The air jet therefore has a very good point of attack on the fibers of the fiber structure at this point. The thread part of the fiber structure that moves spirally in the interior of the swirl part and does not slide along the wall is rotated like a crank by the air flow. Due to the good point of attack according to the invention for the Air flowing into the air inlet bore produces a good swirl effect. This swirl continues up to the drafting system, where the winding fibers are provided outside the spinning triangle. This creates a narrow spinning triangle. The sliver emerges from the drafting device with a width which is at least one and a half times the inside diameter of the injector nozzle. This means that the width of the fiber sliver at the drafting system outlet is wider than the spinning triangle. This targeted production of the wrapping fibers enables the finally parallel lying core fibers to be wrapped with the edge fibers and thus good yarn strength.

The shorter design of the twist part in comparison to the injector part enables on the one hand the optimization of the twist generation and on the other hand the even application of the edge fibers to the core (winding around the core). The latter task requires, first of all, the emergence of a state which at all enables uniform winding, and then the maintenance of flow conditions and the resulting rotational movements which bring about the winding. The friction on the wall of the injector part plays a positive role here.

In the twist part, on the other hand, there should be as little friction of the yarn as possible on the walls of the twister because such friction prevents the twist from being generated. The maximum possible delivery speed for a given wrong twist is also increased by a higher yarn speed. However, the length of the twist part is to be selected so that the spiral can form in the yarn, which (under the effect of the air flow) represents the actual "twist generator".

The length of the injector part is preferably at least 30% and at most up to 100% greater than the length of the Swirl part. The injector part is preferably between 30% and 60% longer than the swirl part. In the preferred embodiment, the injector part is 50% longer than the swirl part.

The length of the swirl part can be selected between 25 and 35 mm (preferably 30 mm). The length of the injector part is preferably at least 40 irim.

It is particularly advantageous to continue the rotation generated in the swirl part back to the drafting device if the injector part has a substantially constant cylindrical inner diameter. This does not hinder the rotation of the thread. In addition, low frictional losses and damage to the thread are brought about. The low-friction rotation of the thread in the injector part is given in particular when the enlarged inner diameter of the twist part is equal to or smaller than the inner diameter of the injector part.

In order to achieve a particularly good crank effect of the air jet on the wrapping fibers, it has been found that the distance of the air inlet bore from the shoulder-shaped extension should be equal to or less than the difference between the inner radii of the swirl part and thus the shoulder height. This ensures that the air jet has a particularly good point of attack on the wrapping fibers.

In one embodiment, an expanded inner diameter of the swirl part between 2.2 and 2.8 mm has been found to be particularly advantageous.

If the axis of the air inlet bore is arranged at right angles to the axis of the interior of the swirl part, the air jet acting on the thread acts particularly effective. The fibers are impacted by the air jet immediately after the shoulder and rotated vigorously.

If several air inlet bores act on the thread, a very good and even application of force to the thread is achieved. It has proven to be advantageous here that the air inlet bores open tangentially and radially outwards into the interior of the swirl part (e.g. according to EP-A-489 686).

A ratio of enlarged inner diameter to length of 1 to 6 to 1 to 16 has proven to be an advantageous length of the swirl part. With a ratio of 1 to 12 to 1 to 14, yarns of the best quality and strength can be achieved.

The air inlet bores arranged in the injector part are advantageously arranged at an angle of 30 ° to the axis of the injector part. A good winding around the core fibers by the edge fibers is achieved if the width of the fiber sliver emerging from the drafting system is greater than the inside diameter of the injector part. A width and a half of the sliver compared to the inside diameter of the injector part has been found to be particularly advantageous. In this case, the sliver is loosely fed into the air jets and can therefore be easily twisted.

In one embodiment it has proven to be particularly advantageous that the distance of the air inlet bore from the shoulder-shaped extension in the swirl part is less than 0.5 mm. Very good spinning results could thus be achieved.

bis Fig. 11 Diagramme zur Erklärung der Wirkung der Teile, die in den Figuren 1 und 2 dargestellt sind.The invention is explained in more detail below with reference to the figures. It shows a swirl device a detail of a shoulder-shaped extension a section through the swirl part in the area of air inlet holes a side view of a suitable drafting device a view in the direction II (FIG. 4), and

to Fig. 11 are diagrams for explaining the effect of the parts shown in Figures 1 and 2.

1 shows a device according to the invention for spinning a fiber sliver. An injector part 1 and a swirl part 2 form a pneumatic swirl device. This swirl device is arranged after a pair of delivery rollers 3, 4 in the running direction of a sliver (not shown). The delivery roller pair 3, 4 is the last roller pair of a drafting system, in which a delivered fiber sliver is drawn down to spinning strength. The sliver comes out of the delivery rollers 3, 4 in a width which is larger than the inside diameter A of the injector part 1. The sliver emerging from the delivery roller pair 3, 4 reaches an interior 12 of the injector part 1 Air flows acted upon, which reach the interior 12 through air inlet bores 10, 11. The air inlet bores 10, 11 are arranged at an angle α in the injector part 1. An angle of about 30 ° between the axis of the injector part 1 and the axis of the air inlet bore has proven to be advantageous. With this angle α, particularly good guidance of the future wrapping fibers is achieved. In order to achieve as little friction as possible and good propagation of rotation up to the nip point on the delivery rollers 3, 4, the interior 12 of the injector part 1 is cylindrical.

The swirl part 2 is arranged at a short distance from the injector part 1. The sliver is on entry led into the swirl part 2 first into a narrow point 220. The constriction 220 has a diameter C which is smaller than the diameter A of the injector part 1. On the other hand, the diameter C is not so small that the constriction 220 acts as a twist stop on the thread or can become blocked when passing through a thick point in the yarn. The narrowing 220 is followed by a shoulder-shaped widening to the diameter D. An advantageous diameter D has a value between 2.2 and 2.8 mm. The constriction should be short in order to keep the friction of the thread on the wall of constriction 220 low. Immediately after the shoulder-shaped expansion to the diameter D, air inlet bores 200, 210 are arranged, through which air flows into the interior 230. As a result of the shoulder-shaped widening, it is particularly advantageously achieved that the air entering can very well act on the thread part located in the interior 230. The good point of attack for the air also produces a good swirl effect on the thread. The thread that does not slide along the wall of the interior 230 at the location of the air inlet bores 200, 210 is rotated like a crank by the air flow. This rotation is largely propagated up to the nip point on the delivery rollers 3, 4. Because there is no twist reduction due to the constriction 220, stable spinning conditions are created which result in good yarn strength. The wrapping fibers that lie around the yarn core can be generated in a targeted and controlled manner by the width of the fiber sliver emerging from the drafting device. As a result, the inner fibers can be wrapped well by the outer fibers of the yarn and thus good yarn strength can be obtained.

Due to the large inside diameter A of the injector part, the thread is fed to the twist part 2 in such a way that good rotation can take place. With that they have through the Air inlet bores 200, 210 air flows acting on the thread part have a large lever arm. A particularly good way of twisting the thread has been to arrange the air inlet bores 200, 210 at right angles in their projection to the axis of the twist part 2.

To reduce the frictional force of the thread part rotating in the injector part 1 and in the swirl part 2, it has proven to be very good that the swirl part 2 is shorter than the injector part 1. This largely prevents damage to the thread due to friction on the inner wall of the interior 230. This leads to a high quality yarn.

The optimal length ratios are explained below with reference to FIGS. 6 to 11. Tests have shown that the swirl part 2 can have a length of approximately 30 mm (between 25 and 35 mm). The partial length between the air inlet openings and the outlet from the nozzle can be approximately 20 mm (between 18 and 22 mm).

A ratio of enlarged internal diameter D to length L of the swirl part 2 of 1: 6 to 1:16 has proven to be particularly advantageous. The interior 230 can be widened conically in the thread running direction. This is indicated by the dashed line in FIG. 1. The conical widening of the interior space 230 is a further measure to reduce the thread friction. In contrast, it has proven to be advantageous if the interior 12 of the injector part 1 is cylindrical.

Tests have also shown that the injector part 11 should have a length of approximately 45 mm (between 40 and 50 mm). It is not necessary to have more than two air inlets. provide holes, and they can be arranged in the middle third of the injector part. The length of the zone between the mouths of the air inlet bores and the outlet of the injector part is preferably approximately the same as the length of the free-standing part of a wrapping fiber.

Such a nozzle is to be placed as close as possible to the delivery roller pair of the drafting system. The suction flows generated by the injector part 1 are thus able to guide the "edge fibers" (wrapping fibers) supplied by the drafting system into the nozzle. The larger diameter favors this suction effect.

FIG. 2 shows a detail of the shoulder-shaped expansion and the arrangement of the air inlet bores 200, 210. When the constriction 220 is expanded to the interior 230, a shoulder height c results. It has been found that a particularly effective attack of the air streams on the sliver can be achieved when a distance b of the air inlet bore 210 from the shoulder-shaped enlargement is equal to or less than the difference between the inner radii of the swirl part and thus equal to or less than the shoulder height c is. 0.5 mm was determined as a particularly advantageous value for the distance b. The air inlet bores 200, 210 advantageously have a diameter of approximately 0.3 mm.

3 shows a sketched section through the swirl part 2 in the area of the air inlet bores 200, 210. The air inlet bores 200, 210 have a lateral offset d. The air inlet bores 200, 210 open essentially tangentially into the interior 230. Corresponding to the offset d of the air inlet bores shown on the swirl part 2, The air inlet bores 10, 11 can also open into the injector part 1. Due to the lateral offset d, the air jet acts in a particularly effective manner on the thread part for rotation.

It has proven to be particularly effective if a multiplicity of air inlet bores are arranged uniformly on the circumference of the injector part 1 and the swirl part 2. In the preferred arrangement, at least four and preferably eight air inlet bores are provided. The higher the number of bores, the smaller their cross sections, and the number would ultimately be limited. The higher number results in a substantially more uniform vortex formation in the channel of the twist part 2, which favors the transfer of energy to the yarn for the production of false twist.

In FIG. 4, reference numerals 110, 120 indicate the pair of intake rollers of a drafting system. A belt passes through a draft zone 13 and enters between two adjoining debris of a pair of aprons 16, 17 whose aprons 16, 17 are guided around a lower apron roller 14 or an upper apron roller 15, and deflecting bodies 18, 19 and 37, 38, respectively.

The deflecting bodies 18, 19 present in the conveying direction F at the end of the strands of straps 16, 17 lying against one another, in cooperation with the deflecting bodies 37, 38 provided at the side spacing and the strapping rollers 14, 15 ensure relatively acute wrap angles α, β in the region of the subsequent delivery rollers 20, 21 in such a way that the exit of the double-reel tape guide thus formed is located within the entrance gusset of the delivery rollers 20, 21. The main draft zone 22 of the drafting system shown is located between the pair of apron rollers 14, 15 and the delivery roller pair 20, 21.

Between the clamping line 23 of the pair of delivery rollers 20, 21 and the exit of the double apron belt guide 16, 17, 18, 19 there is a condenser 26, which is designed to be small in accordance with the available dining space, which according to FIG. 5 has a widthwise direction 4 has an elongated shape which stretches straps 16, 17 and, according to FIG. 4, is designed with its surfaces facing the delivery rollers 20, 21 to be complementary to the parts of the surfaces of the delivery rollers 20, 21 opposite it. The surface of the condenser 26, which is essentially triangular in cross section, facing the straps 16, 17 is largely adapted to the shape of the guide surfaces 24, 25 of the deflection bodies 18, 19 in order to form the straps 26, 27 to form the acute wrap angles α, ß are led around.

It is important that the condenser 26 rests on the circumferential surface of the lower delivery roller 20, but is at a small distance 29 relative to the upper delivery roller 21. In this way it is achieved that the condenser 26, which preferably consists of low-friction plastic material, only rests on the delivery roller 20, which is generally made of metal, where it can slide with little friction, while avoiding contact with the delivery roller 21 made of rubber. This avoids unnecessary wear on the delivery top roller.

While the lower rollers 110, 14, 20 consist of metal, in particular steel hardened on the surface, the counter rollers 120, 15, 21 are made of elastic material, such as rubber. The minimum space between the clamping line 23 of the delivery rollers 20, 21 and the exit of the double-groove guide 16, 17, 18, 19 is thus used to accommodate the condenser according to FIGS. 4 and 5, which has a one on the input side Has funnel shape and is provided on its side facing the delivery lower roller 20 with a slot 35 open towards the delivery lower roller 20.

Below the drafting system shown in FIGS. 4 and 5, the usual suction is provided in the form of a channel 34 extending perpendicular to the axes of the rollers.

This drafting system is formed according to German patent application No. 4230314 dated September 10, 1992. A condenser can also be provided in the pre-delay field, e.g. according to EP-A-449073 or the further development described in German Patent Application No. 4230317 dated September 10, 1992. has been described. These condenser designs give good control over the width of the fiber stream emerging from the drafting system without disturbing the warping of the band. The delay can also be compensated for by an apron arrangement according to EP-A-450361, a further development of this variant being described in US patent application SN 08/010265 of January 28, 1993. The content of the applications mentioned is hereby included in the present application.

The effects of the various elements of the system are explained in more detail using the diagrams in FIGS. 6 to 11. These simplified diagrams each represent only a short section of the entire spinning process, the section under consideration migrating from the "fiber delivery point" (FIG. 6) at the drafting system exit to the finished spun yarn (FIG. 11) at the exit of the twist part 2 "". The diagrams are designed to explain functions. They are not true to scale (even among one another).

forms. The yarn core GK and the wrapping fibers therefore rub against the inner surface Fp of the channel. As a result, the initially free-standing end of each wrapping fiber is wound around the yarn core. Each rotation of the yarn core around the axis of the channel gives approximately one rotation of the wrapping fibers around the yarn core. Up to the outlet AG of the injector part 1, each wrapping fiber should, if possible, loop around the yarn core over the entire length available for the wrapping.

The ratios in the swirl part 2 (FIG. 11) are different. The fiber structure is already completely wrong-turned and has a solid structure. This solid structure is now transformed into a spiral by the newly entering air currents. The air currents themselves form a vortex W in the swirl part 2, and energy is transferred from this vortex to the yarn spiral. The rotation of this piece of yarn about the longitudinal axis of the channel produces "upstream" from the twist part the aforementioned false twist in the yarn core, which essentially propagates up to the spinning triangle on the drafting system. (Downstream from the swirl part 2, this rotation dissolves again because it is a wrong rotation - but this is not the subject of the invention and is not explained in more detail here.)

The spiral drive requires a certain zone where the air currents can act on the spiral. (Swirl part 2). In this zone a vortex which is as uniform as possible must form and as much energy as possible must be transferred from this vortex to the yarn piece. However, this procedure is local, because

the air vortex, e.g. gradually deteriorated by friction on the inner surface of the swirl part 2

- On the other hand, the friction between the yarn piece and the same inner surface opposes the rotation of the yarn piece. The effective effect of the swirl part therefore arises within a zone which is significantly shorter than that zone in the injector part 1 which is necessary for winding the wrapping fibers.

The direction of rotation of the air flow in the injector part must be reversed compared to the direction of rotation in the swirl part, in order to apply the wrapping fibers provided by the drafting device to the yarn core with a direction of rotation opposite to the false twist (FIG. 10).

The invention is not restricted to the exemplary embodiment shown.

Claims

Claims 1. A device for spinning a fiber sliver with a drafting device and a pneumatic swirl device directly downstream of the drafting device, which consists of an injector part (1) and a swirl part (2) adjoining it with an intermediate space, the inside diameter of the swirl part (2 ) is expanded shoulder-like and immediately after the shoulder-shaped expansion of the inner diameter an air inlet bore 820, 21) into the interior (23) of the swirl part (29), characterized in that the swirl part (2) is shorter than the injector part (1) iεt, the length of the twist part being selected such that a yarn spiral can form. 2. Device according to claim 1, characterized in that the injector part (1) has an essentially constant ^" cylindrical inner diameter (A). 3. Device according to claim 1 or 2, characterized in that the enlarged inner diameter (D) of the swirl part (2) is equal to or smaller than the inner diameter (A) of the injector part (1). 4. Device according to one of claims 1 to 3, characterized in that the enlarged inside diameter (D) of the swirl part (2) is 2.2 to 2.8 mm. 5. Device according to one of claims 1 to 4, characterized in that the swirl part (2) has a ratio of expanded inner diameter (D) directly after the Shoulder to length (L) from 1 to 6 to 1 to 16, preferably 1 to 12 to 1 to 14. 6. Device according to one of claims 1 to 5, characterized in that the distance (b) of the air inlet bore (20, 21) from the shoulder-shaped extension is equal to or less than the shoulder height (c) of the swirl part (2). 7. Device according to one of claims 1 to 6, characterized in that the distance (b) of the air inlet bore (20, 21) of the swirl part (2) from the shoulder-shaped extension is equal to or less than 0.5 mm. 8. Device according to one of claims 1 to 7, characterized in that the axis of the air inlet bore (20, 21) has a right angle (β) in its projection to the axis of the swirl part (2). 9. Device according to one of claims 1 to 8, characterized in that the axis of the air inlet bore (10, 11) has an angle (α) of approximately 30 ° in its projection to the axis of the injector part (1). 10. Device according to one of claims 1 to 9, characterized in that the air inlet bore (10, 11; 20, 21) mün¬ substantially tangentially into the interior (12; 23) of the injector and / or the swirl part (2) det. 11. The device according to any one of claims 1 to 10, characterized in that the air inlet bore (10, 11; 20, 21) is offset outwards into the interior (12; 23) of the injector part (1) and / or the swirl part (2 ) flows out. 12. Device according to one of claims 1 to 11, characterized in that three or more (preferably four or more) air inlet bores (10, 11; 20) are distributed uniformly on the circumference of the injector part (1) and / or the swirl part (2) , 21) are arranged. 13. Device according to one of claims 1 to 12, characterized in that the width (B) of the sliver emerging from the drafting device is greater than the inside diameter (A) of the injector parts (1).