Thread-Guiding Unit, Open-End Spinning Machine and Method for Operating a Spinning Station

Abstract

This invention relates to a thread guide unit (6) for drawing off a thread (4) from a rotor (2) of a spinning unit (1) of an open-end spinning machine with a draw-off tube (18) and a compressed air nozzle (21). In accordance with the invention, it is proposed that thread outlet element (19) is provided, a thread outlet element (19) is provided and 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). The invention also relates to an open-end spinning machine with a multiple number of spinning units (1), whereas each spinning unit (1) features a spinning assembly (3), a thread guide unit (6) in accordance with the preceding description, draw-off rollers (5), a spooling unit (9, 11) and a thread setting unit (15, 14, 16). The invention further relates to a method for operating a spinning unit (1) of an open-end spinning machine, whereas, if the thread (4) must be set, a thread setting unit (15, 14, 16) moves a thread end (17) to the thread guide unit (6), where the thread end (17) is initially fed into the thread guide unit (6) by a negative pressure prevailing in the spinning assembly (3) and is then sucked into the spinning assembly (3), whereas a compressed air flow, which emerges in particular from a compressed air nozzle (21) of the thread guide unit (6) supports the sucking in of the thread end (17) into the spinning assembly (3), in a manner synchronized with the setting of the thread (4).

Claims

1. Thread guide unit for drawing off a thread (4) from a rotor (2) of a spinning unit (1) of an open-end spinning machine with a draw-off tube (18) and a compressed air nozzle (21), characterized in that a thread outlet element (19) is provided and 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).

2-19. (canceled)

Description

[0033] Further advantages of the invention are described in the following embodiments. The following is shown:

[0034] FIGS. 1a, 1b and 1c Schematic side views of a spinning unit of an openend spinning machine,

[0035] FIG. 2 A longitudinal section of a thread guide unit,

[0036] FIG. 3 A longitudinal section of an additional thread guide unit,

[0037] FIG. 4 A longitudinal section of an additional thread guide unit,

[0038] FIG. 5 A side view of a thread outlet element,

[0039] FIGS. 6a, 6b and 6c Cross-sections through different thread guide units and

[0040] FIG. 7 A cross-section through an additional thread guide unit and

[0041] FIG. 8 A cross-section through an additional thread guide unit.

[0042] FIG. 1 a 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 pulled out of the rotor 2 by a pair of draw-off rollers 5 via a thread guide unit 6. Thereby, 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. Thereby, the cross-wound bobbin 10 is held by a bobbin holder 11 and is driven by a drive roller 12.

[0043] 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 an engine 14, and a thread catcher 16 are not required.

[0044] 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 attached to the spinning assembly 3. For seeking the thread end 17, the suction nozzle 15 is displaced by the engine 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 against the direction of rotation during spinning operation, until the thread end 17 is sucked into the suction nozzle 15. Then, the suction nozzle 15 from the engine 14 is removed again from the cross-wound bobbin 10, 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.

[0045] 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.

[0046] In the further course of the setting 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 from the pair of draw-off rollers 5. Subsequently, the actual setting takes place, in which the rotor 2 is ramped up to its setting 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.

[0047] 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. Thereby, 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.

[0048] During spinning operation, a thread from the rotor is drawn off from 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.

[0049] 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.

[0050] 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.

[0051] Furthermore, the thread guide unit 6 features a negative pressure connection 25, which is also formed as an air coupling. Negative pressure is then 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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. Thereby, 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 from the thread is blocked or at least weakened, and the light sensor is registered, such 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 setting process can then be carried out more precisely.

[0056] 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 spun 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 rotation 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 setting 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] Furthermore, a combination of the embodiments of FIGS. 7 and 8 is also conceivable. The compressed air is thereby 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.

[0065] 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

[0066] 1 Spinning unit [0067] 2 Rotor [0068] 3 Spinning assembly [0069] 4 Thread [0070] 5 Pair of draw-off rollers [0071] 6 Thread guide unit [0072] 7 Groove [0073] 8 Holding spring [0074] 9 Traverse unit [0075] 10 Cross-wound bobbin [0076] 11 Bobbin holder [0077] 12 Drive roller [0078] 13 Compressed air nozzle [0079] 14 Engine [0080] 15 Suction nozzle [0081] 16 Thread catcher [0082] 17 Thread end [0083] 18 Draw-off tube [0084] 19 Thread outlet element [0085] 20 Compressed air connection [0086] 21 Compressed air nozzle [0087] 22 Ring-shaped air chamber [0088] 23 Mouth [0089] 24 Compressed air coupling [0090] 25 Negative pressure connection [0091] 26 Bend [0092] 27 Twist stop means [0093] 28 Thread sensor [0094] 29 Side arm [0095] 30 Thread end preparation assembly [0096] 31 Main arm [0097] 32 Air directing element [0098] 33 Opening [0099] D Internal diameter [0100] T Thickness