Thread-guiding unit, open-end spinning machine and method for operating a spinning station

Abstract

A thread guide unit is used for drawing off a thread out of a rotor of a spinning unit of an open-end spinning machine. The thread guide unit includes a draw-off tube, and a compressed air nozzle configured with the draw-off tube. A thread outlet element extends into the draw-off tube. The compressed air nozzle includes a mouth formed as a gap between an inner diameter surface of the draw-off tube and the thread outlet element. A method for operating a spinning unit of an open-end spinning machine having the thread guide unit is also provided.

Claims

1. A thread guide unit for drawing off a thread out of a rotor of a spinning unit of an open-end spinning machine, comprising: a draw-off tube, the draw-off tube having a first end, an opposite second end, and a continuous inner diameter surface between the first end and the opposite second end, wherein the draw-off tube is configured such that during spinning operations at the spinning unit, the first end is adjacent and concentric with an open-end of the rotor to draw a spun yarn out from a center of the rotor and into the draw-off tube; a compressed air nozzle configured with the draw-off tube; a thread outlet element extending into the second end of the draw-off tube; the compressed air nozzle comprising a mouth formed as a gap between the inner diameter surface of the draw-off tube and the thread outlet element, wherein compressed air is directed into and along the gap from the compressed air nozzle; and means for generating a vortex in the compressed air flowing through the gap and into the draw-off tube to generate or maintain a twist in the thread in the draw-off tube.

2. The thread guide unit according to claim 1, wherein the mouth of the compressed air nozzle has one of a ring or semi-circular shape and comprises a plurality of openings arranged along a ring that extends radially outward towards the inner diameter surface of the draw-off tube.

3. The thread guide unit according to claim 1 wherein the vortex generating means comprises air directing elements in the gap formed on one or both of the inner diameter surface of the draw-off tube or an outer diameter surface of the thread outlet element.

4. The thread guide unit according to claim 1, wherein the vortex generating means comprises an offset of the compressed air nozzle relative to an axis of the draw-off tube so as to introduce the compressed air to the mouth with a tangential component to generate the vortex.

5. The thread guide unit according to claim 1, further comprising a compressed air coupling on the compressed air nozzle to connect a compressed air hose.

6. The thread guide unit according to claim 1, wherein a ring-shaped air chamber is formed between the draw-off tube and the thread outlet element.

7. The thread guide unit according to claim 1, wherein the draw-off tube comprises a bend such that a direction of a part of the draw-off tube on which the thread outlet element is arranged corresponds to a draw-off angle of thread from the thread guide unit.

8. The thread guide unit according to claim 1, wherein the draw-off tube further comprises a twist stop device.

9. The thread guide unit according to claim 1, wherein the draw-off tube further comprises a thread sensor.

10. The thread guide unit according to claim 1, further comprising a fastening device that connects the thread guide unit to the spinning unit.

11. The thread guide unit according to claim 1, further comprising a negative pressure connection provided on the draw-off tube.

12. The thread guide unit according to claim 1, wherein the inner diameter surface of the draw-off tube comprises a cylindrical surface with a diameter (D) between 2 mm and 4 mm and the gap has a thickness (T) that is between 0.5% and 15% of the inner diameter (D) of the draw-off tube.

13. An open-end spinning machine with a plurality of spinning units, wherein each spinning unit comprises a spinning assembly, draw-off rollers, a winding unit, a thread piecing unit, and the thread guide unit according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages of the invention are described in the following embodiments. The following is shown:

(2) FIGS. 1a, 1b and 1c are schematic side views of a spinning unit of an open-end spinning machine;

(3) FIG. 2 is a longitudinal section of a thread guide unit;

(4) FIG. 3 is a longitudinal section of an additional thread guide unit;

(5) FIG. 4 is a longitudinal section of an additional thread guide unit;

(6) FIG. 5 is a side view of a thread outlet element;

(7) FIGS. 6a, 6b and 6c are cross-sections through different thread guide units;

(8) FIG. 7 is a cross-section through an additional thread guide unit; and

(9) FIG. 8 is a cross-section through an additional thread guide unit.

DETAILED DESCRIPTION

(10) 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.

(11) FIG. 1a shows a schematic side view of a spinning unit 1 of an open-end spinning machine during spinning operation. Fiber material is introduced into a rotor 2 of a spinning assembly 3 of the spinning unit and is spun into a thread 4. The thread 4 is drawn off out of the rotor 2 by a pair of draw-off rollers 5 via a thread guide unit 6. The thread guide unit 6 features a groove 7, into which a holding spring 8 of the spinning assembly 3 engages and thus connects the thread guide unit 6 with the spinning assembly 3. After the pair of draw-off rollers 5, the thread 4 is wound by a traverse unit 9 onto a cross-wound bobbin 10. The cross-wound bobbin 10 is held by a bobbin holder 11 and is driven by a drive roller 12.

(12) At time intervals, a compressed air flow is blown through a compressed air nozzle 13 of the thread guide unit 6 for cleaning the thread guide unit 6 and the spinning assembly 3. Dirt and fiber fly are thereby detached and sucked off by a vacuum device (not shown here) of the spinning assembly 3. During spinning operation, a suction nozzle 15, which can be displaced by a drive 14, and a thread catcher 16 are not required.

(13) Referring to FIG. 1b, after a thread break or a clearer cut, the thread 4 runs onto the cross-wound bobbin 10. In order to obtain a continuous thread 4 on the cross-wound bobbin 10, the thread end 17 must initially be found and then located at the spinning assembly 3. For seeking the thread end 17, the suction nozzle 15 is displaced by the drive 14 in such a manner that the opening of the suction nozzle 15 is located just above the surface of the cross-wound bobbin 10. The cross-wound bobbin 10 is then rotated by the drive roller 12 slowly opposite the direction of rotation during spinning operation until the thread end 17 is sucked into the suction nozzle 15. Then, the suction nozzle 15 is removed again from the cross-wound bobbin 10 by the drive 14, such that the thread 4 is tensioned between the cross-wound bobbin 10 and the suction nozzle 15. The thread catcher 16 can then grip the tensioned thread 4. Such point in time is shown in FIG. 1b.

(14) The thread 4 is then inserted by the thread catcher 16 into the traverse unit 9 and the draw-off roller pair 5, and is moved up to the opening of the thread guide unit 6. There, the thread 4 is sucked into the thread guide unit 6 by the negative pressure prevailing in the spinning assembly 3. This process is supported by a compressed air flow blown through the compressed air nozzle 13. The thread end 17 is now located in the thread guide unit 6, as shown in FIG. 1c.

(15) In the further course of the piecing process, the pair of draw-off rollers 5 is then rotated backwards, such that the thread end 17 is moved further into the thread guide unit 6 up to the rotor 2 by the negative pressure prevailing in the spinning assembly 3, assisted by the compressed air flow from the compressed air nozzle 13. At the rotating rotor edge, the thread end 17 is then separated and prepared. Thereupon, the thread end 17 is withdrawn somewhat by the pair of draw-off rollers 5. Subsequently, the actual piecing takes place, in which the rotor 2 is ramped up to its piecing speed and the pair of draw-off rollers 5 is rotated backwards. The thread end 17 is thereby conveyed into the rotor 2, where it is connected to fibers located there, by the negative pressure prevailing in the spinning assembly 3, combined with a synchronized compressed air flow from the compressed air nozzle 13. The normal spinning operation is then resumed.

(16) FIG. 2 shows a longitudinal section of a simple thread guide unit 6. The thread guide unit 6 features a draw-off tube 18 with an inside diameter D along with a thread outlet element 19. A compressed air connection 20 leads to a compressed air nozzle 21, which is provided as a recess in the draw-off tube 18. The compressed air nozzle 21 also comprises a ring-shaped air chamber 22, which is formed between the draw-off tube 18 and the thread outlet element 19. The compressed air is distributed evenly through this ring-shaped air chamber 22. Finally, a mouth 23 of the compressed air nozzle 21 is formed as a gap between the draw-off tube 18 and the thread outlet element 19. This enables a particularly compact structural shape. Herein, the thickness T of this gap influences the strength of the compressed air flow that can be achieved. The mouth 23 is also ring-shaped, such that the compressed air flow can emerge in a uniformly distributed manner, and can flow around the thread from all sides. Thus, the compressed air flow is most efficiently utilized and the thread is treated most gently.

(17) During spinning operation, a thread from the rotor is drawn off by a pair of draw-off rollers through the draw-off tube 18. The thread leaves the thread guide unit 6 at the thread outlet element 19. As described above, the compressed air nozzle 21 is required to blow the thread in the direction of the rotor. In addition, a compressed air flow blown through the compressed air nozzle 21 can be used to clean the draw-off tube and/or the spinning assembly.

(18) With the following description of the alternative thread guide unit 6 shown in FIG. 3, the same reference signs are used for characteristics that, in their design and/or mode of operation, are identical and/or at least comparable in comparison to the first embodiment shown in FIG. 2. To the extent that such are not described once again in detail, their designs and/or modes of action correspond to the designs and modes of action of the characteristics described above. For the sake of clarity, the internal diameter D and the thickness T are no longer marked in these and the following figures.

(19) For the more rapid connection and disconnection of a compressed air hose, the thread guide unit 6 features a compressed air coupling 24. Compared to a conventional compressed air connection, this provides a time advantage, in particular during maintenance and/or cleaning work.

(20) Furthermore, the thread guide unit 6 features a negative pressure connection 25, which is also formed as an air coupling. Negative pressure is switched on, for example, via the negative pressure connection 25, if a thread end is first sucked into the thread guide unit 6. This negative pressure then assists the negative pressure prevailing in the spinning assembly and sucks off at least one part of the compressed air blown in by the compressed air nozzle 21. The negative pressure is also switched on if the draw-off tube 18 is cleaned by means of compressed air. Dirt and fiber fly are then sucked through the negative pressure line.

(21) The thread guide unit 6 further comprises a groove 7. In cooperation with holding springs of the spinning assembly, this groove 7 serves to fasten the thread guide unit 6 to the spinning assembly.

(22) The draw-off tube 18 features a bend 26, such that the thread is at least essentially drawn off in the direction of the part of the draw-off tube 18 on which the thread outlet element 19 is arranged. Thus, the change in direction of the thread at the thread outlet element 19 is very small, which results in a correspondingly low friction of the thread at the thread outlet element 19.

(23) The draw-off tube 18 also features twist stop means 27. As a result, the twist generated by the rotation of the rotor is stopped in the thread, which results in a defined twist in the thread, and the thread properties thus remaining constant.

(24) Finally, a thread sensor 28 is provided in the draw-off tube 18. The thread sensor 28 consists of a light barrier unit 28.1 and a mirror 28.2. By this, a light source of the light barrier unit 28.1 radiates light onto the mirror 28.2. Then, the light reflected by the mirror 28.2 is in turn detected by a light sensor of the light barrier unit 28.1. If a thread is located in the draw-off tube 18 in the area of the thread sensor 28, the light is blocked by the thread or at least weakened, and the light sensor determines, that a thread is located in the draw-off tube 18. Since the position of the thread sensor 28 in the draw-off tube 18 is known, even the position of the thread end can be registered, if the point in time at which the thread blocks or releases the light is recorded. With the assistance of the detected position of the thread end, the piecing process can then be carried out more precisely.

(25) With the embodiment of a thread guide unit 6 shown in FIG. 4, the draw-off tube 18 features a side arm 29. This side arm 29 leads to a thread end preparation assembly 30, which is shown here only schematically. If, for example, the thread is to be pieced after a thread break, then, as described above, the thread end is sucked into the thread guide unit 6. If negative pressure is then applied to the side arm 29, the thread end reaches the thread end preparation assembly 30 via the side arm 29, where the thread end is shortened and the twist of the fibers is partially canceled. The thread end is now withdrawn somewhat, such that it is no longer located in the side arm 29. For the further piecing of the thread end, negative pressure is now applied to the main arm 31 of the draw-off tube 18, and the process continues as described above.

(26) FIG. 5 shows a side view of an alternative embodiment of a thread outlet element 19. Such thread outlet element 19 is provided with air directing elements 32. If compressed air is now blown between the thread outlet element 19 and the draw-off tube 18, an air vortex is generated in the compressed air flow through the air directing elements 32. With the assistance of such air vortex, a twist, typically a Z-twist, is generated in the thread, or the twist is maintained in the thread and does not loosen. However, the air directing elements 32 can also be assigned to the draw-off tube 18, or partially to the thread outlet element 19 and partially to the draw-off tube 18.

(27) FIGS. 6a, 6b and 6c show cross-sections of different embodiments of thread guide units 6, whereas the cross-sections are in the area of the mouth 23.

(28) In FIG. 6a, the mouth 23 is ring-shaped. This ensures a uniform circulation of the thread with compressed air and is particularly gentle to the thread.

(29) FIG. 6b shows a semi-circular mouth 23. Such a mouth 23 is used in particular if, for example, a specific direction of the thread is predetermined by a bend 26 in the draw-off tube 18, and the compressed air flow is to direct the thread in such direction.

(30) Furthermore, FIG. 6c shows a mouth 23 with which a multiple number of openings 33 are arranged along a ring, of which only two are provided with a reference sign for the sake of clarity. Such a design of the mouth 23 offers an increased stability of the thread guide unit 6 in the area of the mouth 23.

(31) Furthermore, FIG. 7 shows a cross-section through an additional thread guide unit 6. With this thread guide unit 6, the compressed air nozzle 21 opens directly into the mouth 23. In addition, the compressed air nozzle 21 is offset with respect to the axis of the draw-off tube 18 and of the thread outlet element 19 and is thus arranged with components tangential to the mouth 23. By means of this offset arrangement of the compressed air nozzle 21, the air that is blown receives a tangential component, such that, here as well, an air vortex is generated, with the aforementioned advantages. A combination of the compressed air nozzle arranged tangentially with the mouth with air directing elements is also conceivable, such that an air vortex of the correct strength is generated.

(32) Finally, FIG. 8 shows a cross-section through an additional thread guide unit 6. This thread guide unit 6 features, in addition to the mouth 23, a ring-shaped air chamber 22. Similar to the embodiment of FIG. 7, the compressed air nozzle 21 is offset with respect to the axis of the draw-off tube 18, the thread outlet element 19 and the ring-shaped air chamber 22, and thus features a component tangential to the mouth 23. Here as well, the blown air receives a tangential component through the offset arrangement of the compressed air nozzle 21. This also generates an air vortex, with the advantages described above.

(33) Furthermore, a combination of the embodiments of FIGS. 7 and 8 is also conceivable. In this case the compressed air is blown in such a way that part of the compressed air initially flows into the ring-shaped air chamber 22 and only reaches the mouth 23 from there. The other part of the compressed air is blown directly into the mouth 23. Thus, both parts of the compressed air flow come together once again in the mouth. Thus, a particularly effective air vortex can be generated.

(34) This invention is not limited to the illustrated and described embodiments. Variations within the scope of the claims, just as the combination of characteristics, are possible, even if they are illustrated and described in different embodiments.

LIST OF REFERENCE SIGNS

(35) 1 Spinning unit 2 Rotor 3 Spinning assembly 4 Thread 5 Pair of draw-off rollers 6 Thread guide unit 7 Groove 8 Holding spring 9 Traverse unit 10 Cross-wound bobbin 11 Bobbin holder 12 Drive roller 13 Compressed air nozzle 14 Engine 15 Suction nozzle 16 Thread catcher 17 Thread end 18 Draw-off tube 19 Thread outlet element 20 Compressed air connection 21 Compressed air nozzle 22 Ring-shaped air chamber 23 Mouth 24 Compressed air coupling 25 Negative pressure connection 26 Bend 27 Twist stop means 28 Thread sensor 29 Side arm 30 Thread end preparation assembly 31 Main arm 32 Air directing element 33 Opening D Internal diameter T Thickness