Thread draw-off nozzle

Abstract

A thread draw-off nozzle for an open-end rotor spinning device includes a front surface, a nozzle bore, and a funnel-shaped yarn deflection surface connecting the front surface and the nozzle bore. The front surface adjoins the yarn deflection surface. The front surface and the yarn deflection surface form an effective diameter (D.sub.W) of the thread draw-off nozzle. The effective diameter (D.sub.W) of the thread draw-off nozzle is less than 8 mm, and the yarn deflection surface comprises a radius of curvature (R) of less than 2.5 mm.

Claims

1. A thread draw-off nozzle for an open-end rotor spinning device, comprising: a front surface; a nozzle bore; a funnel-shaped yarn deflection surface connecting the front surface and the nozzle bore, the front surface adjoining the yarn deflection surface; the front surface and the yarn deflection surface forming an effective diameter (D.sub.W) of the thread draw-off nozzle; wherein the effective diameter (D.sub.W) of the thread draw-off nozzle is less than 8 mm, and the yarn deflection surface comprises a radius of curvature (R) of less than 2.5 mm; and a head diameter (D.sub.K) that is less than 10 mm.

2. The thread draw-off nozzle according to claim 1, wherein the yarn deflection surface tangentially adjoins the front surface.

3. The thread draw-off nozzle according to claim 1, wherein the yarn deflection surface comprises a plurality of macrostructures arranged in a radial manner.

4. The thread draw-off nozzle according to claim 3, wherein the macrostructures comprise notches.

5. The thread draw-off nozzle according to claim 4, wherein each notch comprises a radially outer notch inlet and a radially inner notch outlet, the radially inner notch outlets extending into the nozzle bore.

6. The thread draw-off nozzle according to claim 4, wherein each notch comprises an inlet wall and a baffle wall, wherein the baffle wall is steeper than the inlet wall relative to a notch bottom arranged between the inlet wall and the baffle wall.

7. The thread draw-off nozzle according to claim 4, wherein each notch comprises an inlet wall and a baffle wall, each notch further comprising a notch bottom arranged between the inlet wall and the baffle wall and comprising a width (B) of between 0.16 mm and 0.22 mm.

8. The thread draw-off nozzle according to claim 7, wherein an angle () of the baffle wall to a center notch plane is between 32.5 and 47.5.

9. The thread draw-off nozzle according to claim 7, wherein a first angle (.sub.1) of a first part of the inlet wall or first part of the baffle wall to a center notch plane is between 32.5 and 47.5, and a second angle (.sub.2) of a second part of the inlet wall or the baffle wall to the first part is between 10 and 20.

10. The thread draw-off nozzle according to claim 5, wherein the yarn deflection surface comprises, at an area of the radially outer notch inlets, a circumferential recess.

11. The thread draw-off nozzle according to claim 4, wherein at least some of the notches comprise an inlet wall and a baffle wall, one or both of the inlet wall and the baffle wall being flat.

12. The thread draw-off nozzle according to claim 4, wherein some of the notches comprise an inlet wall and a baffle wall, one or both of the inlet wall and the baffle wall is kinked or bent.

13. The thread draw-off nozzle according to claim 4, wherein each notch comprises an inlet wall and a baffle wall, each notch further comprising a notch bottom arranged between the inlet wall and the baffle wall and comprising a depth (T) of the notch between 0.14 mm and 0.25 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Additional advantages of the invention are described on the basis of the following presented embodiments. The following is shown:

(2) FIG. 1 is a schematic view of an open-end spinning device with a spinning rotor and a draw-off nozzle;

(3) FIG. 2 is a schematic view of a thread draw-off nozzle with a reduced effective diameter;

(4) FIG. 3 is a schematic sectional view of a thread draw-off nozzle with a reduced effective diameter and with notches;

(5) FIG. 4 is a schematic sectional view of a notch of a thread draw-off nozzle;

(6) FIG. 5 is a schematic sectional view of an additional thread draw-off nozzle with a circumferential recess;

(7) FIG. 6 is an additional embodiment of a thread draw-off nozzle with a circumferential recess; and

(8) FIG. 7 is an additional embodiment of a thread draw-off nozzle with a kinked baffle wall.

DETAILED DESCRIPTION

(9) Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

(10) FIG. 1 shows a schematic sectional view of a spinning rotor 2 and a thread draw-off nozzle 1 in an open-end spinning device, which is shown only partially in the present case. To produce a thread F, the spinning rotor 2 is fed in a known manner with a fiber material broken down into individual fibers. During yarn production, the spinning rotor 2 runs at high rotational speeds, such that the fibers that are fed are deposited in the rotor groove 3 of the spinning rotor 2 in the form of a fiber ring. The newly spun thread F is drawn off continuously via the thread draw-off nozzle 1 and, with its end, extends into the rotor groove 3 of the spinning rotor 2. Thus, due to the rotation of the spinning rotor 2, a crank-like circumferential yarn shank 4, in which the fibers deposited in the rotor groove 3 are integrated, arises. The thread draw-off nozzle 1 is mounted in a manner known per se either in an extension or in an insert of a cover element of the rotor housing 17.

(11) The thread draw-off nozzle 1 features, in the customary manner, a cylindrical nozzle bore 6 and a curved yarn deflection surface 5 for the thread F to be drawn off. Finally, a front surface 16 of the thread draw-off nozzle 1 adjoins the yarn deflection surface 5, on the side of the thread draw-off nozzle 1 turned away from the nozzle bore 6. The front surface 16 can be formed to be sloping in different ways, for example, flat, curved or in the direction of the outer diameter of the thread draw-off nozzle 1, which is designated here with head diameter D.sub.K. The curved yarn deflection surface 5 and the front surface 16 together form an effective diameter D.sub.W of the thread draw-off nozzle 1, which is in contact with the thread F. The nozzle bore 6 is typically coaxial relative to the axis of rotation 15 of the spinning rotor 2, such that, during its drawing off out of the rotor groove 3, the drawn-off thread F is deflected over the yarn deflection surface 5 by about 90. As described above, it is desirable that the rotation introduced into the thread propagates as far as possible into the rotor groove 3, in order to achieve the best possible spinning stability.

(12) FIG. 2 shows, in a schematic sectional view, a thread draw-off nozzle 1, which features a yarn deflection surface 5 with a very small radius of curvature R of less than 2.5 mm and a reduced effective diameter D.sub.W of less than 8 mm. Thus, with the present thread draw-off nozzle, the annular front surface 16 is also greatly reduced. While, with conventional thread draw-off nozzles, an excessive reduction of the radius of curvature R has always been avoided, since, at the same time, this has been associated with a reduction in spinning stability, it has now been surprisingly found that good spinning stability can nevertheless be achieved if, at the same time, the front surface 16 or the total effective diameter D.sub.W is reduced. The reason for this is that, due to the special, overall small dimensions, less false twist is introduced into the thread F, but, at the same time, the propagation of the true rotation into the rotor groove 3 is improved at otherwise identical spinning ratios. Thus, with the same geometry of the spinning rotor 2, solely through the use of the thread draw-off nozzle 1 described, without changes in the rotor speed or the delivery speed, it can increase the total rotation of the thread F to the rotor groove. At the same time, the thread F is gently drawn off through the geometry of the thread draw-off nozzle 1, with a very small effective diameter D.sub.W. Due to the lower friction on the reduced yarn deflection surface 5 and front surface 16, the thread draw-off tension and, at the same time, the temperature stress of the thread F are reduced.

(13) At the same time, the thread draw-off nozzle 1 shown here also features a particularly small head diameter D.sub.K of less than 10 mm. As can be seen again from FIG. 1, a particular large emission surface AF on the part of the rotor housing 17 projecting into the spinning rotor 2, here an extension of a cover element of the rotor housing, is achieved. Thereby, the frictional heat that arises at the thread draw-off nozzle 1, which was already reduced by the reduced yarn deflection surface 5 can be dissipated even better. The thermal load of the thread draw-off nozzle 1 itself can also be thereby reduced. At the same time, due to the reduced surface temperature at the thread draw-off nozzle 1, damage to the drawn-off thread F and yarn breaks are avoided. This has a particularly advantageous effect with chemical fibers. Likewise, contamination of the thread draw-off nozzle 1 is avoided, particularly with chemical fibers.

(14) FIG. 3 shows a thread draw-off nozzle 1, which is additionally provided with notches 7, in a sectional view. Here, the notches 7 (in the present case, two notches 7 can be seen opposite one another) are arranged in the yarn deflection surface 5, but extend into the nozzle bore 6. It has proved to be particularly advantageous if the notch outlet 11, which is defined in the present case by the exit-side intersection point or the exit-side intersection line of the notch bottom 12 with the inner surface of the thread draw-off nozzle 1, is at a spacing A of between 0.1 mm and 0.5 mm away from the entrance of the nozzle bore. For example, the spacing A is 0.25 mm. With this, the entrance of the nozzle bore 6 is defined as the beginning of the constant inner cross-section of the thread draw-off nozzle 1, and in the present case is characterized by the tangential edge between the yarn deflection surface 5 and the nozzle bore 6. In the case of conventional V-shaped notches, the notch inlet 10 is in turn defined by the common intersection point of the inlet wall 8 and the baffle wall 9 with the inner surface of the nozzle funnel 5 or, in the present case, by the entrance-side intersection line of the notch bottom 12 with the inner surface of the nozzle funnel.

(15) FIG. 4 shows a schematic section through a notch 7 of a thread draw-off nozzle 1, with which a particularly good and reliable effect of the notch 7 on the drawn-off thread F can be ensured. The notch 7 features, in a manner known per se, an inlet wall 8 and a baffle wall 9, which the thread F reaches in succession during its crank-shaped circulation over the yarn deflection surface 5. In the present case, the direction of rotation of the thread F is symbolized by an arrow. In contrast to known notch shapes, which have always been designed to be V-shaped, it is now provided that the inlet wall 8 and the baffle wall 9 do not directly adjoin one another; rather, a defined, preferably flat, notch bottom 12 with a defined width B extends between the inlet wall 8 and the baffle wall 9. The notch bottom 12 between the inlet wall 8 and the baffle wall 9 ensures that the thread F reaches the notch base or the flat notch bottom 12 in each case, and thus the notch 7 can exert its effect on the thread F. An undefined jumping of the thread F from the inlet wall 8 directly on the baffle wall 9 can thereby be avoided.

(16) According to the present illustration, the secure reaching of the notch bottom 12 is still supported by the fact that the thread F is led over a comparatively flat inlet wall 8 slowly and gently in the direction of the notch bottom 12. The angle to a center notch plane 14 or to a parallel thereto, as the case may be, preferably measures between 54 and 58 and is designed, for example, at 56. The notch bottom 12 further features a width B of between 0.18 mm and 0.24 mm. For example, the width B of the notch bottom is 0.22 mm. However, the angle of the baffle wall 9 relative to the center notch plane 14 preferably measures between 37 and 42. According to a particularly advantageous embodiment, the angle is 40. This results in a notch angle of + between the inlet wall 8 and the baffle wall 9 of for example, 96. It has also proved to be advantageous for the guidance of the thread F along the notch 7 if the depth T of the notch 7 is between 0.16 mm and 0.20 mm. Thus, the notch shape that is shown contributes not only to improving spinning stability, but also to improving yarn quality.

(17) FIG. 5 shows an additional embodiment of a thread draw-off nozzle 1, with which the yarn-damaging effect of the notch inlet 10 is defused by a circumferential recess 13, in this case a circumferential groove. Thereby, the comparatively sharp transition between the curved yarn deflection surface 5 and the notch 7 can be configured to be more gentle. The circumferential groove preferably features a radius of between 0.15 mm and 0.3 mm, and in the present case extends to the front surface. However, the groove could also be designed in such a manner it only breaks up the yarn deflection surface 5.

(18) FIG. 6 shows another embodiment of a thread draw-off nozzle 1, with which the notch inlets 10 were mitigated by a spherical recess 13. The radius of the spherical recess 13 is preferably matched to the inner diameter DI of the nozzle bore 6, and is between 0.7*DI and 0.9*DI. For example, the radius R2 is 0.8*DI. The aggressive, yarn-damaging effect of the notch inlets 10 can thereby be substantially reduced.

(19) In FIG. 7, a notch 7 is shown, in which the baffle wall 9 is formed to be kinked. The first part of the baffle wall 9 turned towards the notch bottom 12 is inclined at an angle .sub.1 to the center notch plane 14. The second part of the baffle wall 9 turned towards the edge of the thread draw-off nozzle 1 is formed to be more flat and features a second angle .sub.2. With this type of notch 7, a thread treatment that is more gentle than with the notches shown above is possible, since the baffle wall 9 does not brake the thread too strongly. Such a kinked formation is also possible for the inlet wall 8, in addition to or as an alternative to the kinked baffle wall 9.

(20) It has been found that the small radius of curvature in combination with the small effective diameter D.sub.W is particularly advantageous in the case of a thread draw-off nozzle 1 provided with notches 7, since, in addition to increasing the true twist, a false twist is also introduced into the thread F. In doing so, spinning stability is further improved.

(21) Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims.

LIST OF REFERENCE SIGNS

(22) 1 Thread draw-off nozzle 2 Spinning rotor 3 Rotor groove 4 Circumferential yarn shank 5 Yarn deflection surface 6 Nozzle bore 7 Notch 8 Inlet wall 9 Baffle wall 10 Notch inlet 11 Notch outlet 12 Notch bottom 13 Recess 14 Center notch plane 15 Axis of rotation of the spinning rotor 16 Front surface 17 Rotor housing B Width of the notch bottom T Depth of the notch F Thread D.sub.K Head diameter D.sub.I Inner diameter of the nozzle bore D.sub.W Effective diameter A Spacing of the notch outlet from the entrance of the nozzle bore Angle of the inlet wall Angle of the baffle wall R Radius of curvature of the yarn deflection surface AF Emission surface