EP0274016B1 - Piecing method and device for an open-end spinning machine - Google Patents

Description

The present invention relates to a method for piecing an open-end spinning device, in which the thread is drawn off from a bobbin, cut to length and the thread end is brought into a position for insertion into the spinning device to form a thread reserve, and the thread end is returned from the thread reserve to the spinning device and the re-spun thread is drawn off.

It is known that yarns of different characteristics are produced when spinning at different speeds. For this reason, efforts are made in practice to carry out the piecing if possible at production speed. In order to achieve a successful piecing and also a piecing which does not interfere with the yarn, exact timing must be observed when piecing the thread back into the spinning rotor, feeding the fibers and inserting the thread take-off from the spinning rotor. The corresponding units run at the speeds selected for the preparation or for the spinning and are controlled in accordance with the time used. Depending on the thread number to be spun, care should be taken to ensure that the feed starts early so that the appropriate amount of fiber in the rotor is available in good time, with which the thread end to be returned can make appropriate contact before thread take-off begins. If the thread is drawn off too late, the thread is turned over and a thread break occurs. On the other hand, if the dwell time is too short, the end of the thread in the spinning rotor cannot connect sufficiently to the fiber ring, so that a thread breakage also occurs due to the suddenly starting thread pull-off.

According to a generic method, the thread withdrawn from the spool is brought to be spun in front of the mouth of the thread take-off tube (DE-OS 20 12 108). Then the piecing thread is inserted into the thread take-off tube by turning back the bobbin using the negative pressure of the spinning and immediately returned to the collecting groove of the spinning rotor. Because of the inertia of the bobbin, the dwell time of the thread in the spinning rotor is quite long, so that - especially at higher rotor speeds - there is a risk that the thread will be overturned and a thread breakage will occur.

The object of the invention is therefore to provide a method and a device which avoid these disadvantages and enable good piecing at high spinning speeds.

To achieve the object, the thread end is first brought from the position for insertion into the spinning device within the thread take-off tube into a standby position, from which the thread end is returned to the fiber collecting surface by releasing the thread reserve. The return time of the thread for contacting the fibers in the rotor is reduced to a minimum. Precise, yet individual time control at high spinning speeds is made possible and piezers of high quality are achieved. The yarn is returned to the open-end spinning device in two stages, the yarn being metered in the first stage. This first return stage includes the formation of a thread reserve, the release of which is independent of the return rate of the first stage. Through this second stage of thread return, which is brought about by the release of the thread, the thread comes into contact with the fibers on the fiber collecting surface. This thread release not only results in a certain self-control of the direct piecing process, but it also always results in the same conditions.

Preferably, the withdrawal of the re-spun thread begins at a time-definable interval for releasing the thread reserve, so that an adaptation to different materials etc. is possible.

The provision of the thread end for piecing is advantageously carried out in that the thread is cut to a length such that the thread end supplied to the thread take-off tube, forming the thread reserve required for the return delivery from the ready position, extends up to the mouth of the thread take-off tube, and through the coil is returned to the standby position by a certain distance.

If fiber collecting areas of different diameters are used, it is necessary to coordinate the return delivery route accordingly. In order to achieve constant piecing conditions, the actual piecing return should always take place under constant conditions. Therefore, the adaptation to the different diameters is expediently not carried out by the size of the thread reserve, but the distance is determined according to the invention as a function of the diameter of the fiber collecting surface of the open-end spinning device, so that regardless of the diameter of the fiber collecting surface selected in each case, the path of the piecing return delivery is released the thread reserve is always the same size.

In order to enable a particularly rapid release of the thread reserve, this release of the thread reserve is preferably carried out by throwing off the thread.

By the measure that the thread after completion of the return delivery until the normal spinning take-off is subjected to an auxiliary take-off at a greater distance from the open-end spinning device than this spinning take-off, the twist necessary for attachment in the thread can be individually adapted to the thread. The thread take-off is soft, which also favors piecing at high spinning speeds. The number of thread breaks during piecing is reduced and the tensile strength in the piecing is increased significantly.

According to the invention, depending on the construction of the piecing device, the auxiliary trigger can take place independently of the winding or also exclusively through the coil. After a short time, which is sufficient for the auxiliary draw to reach its full speed, the thread is transferred to the draw-off roller pair. Since the thread is already being drawn off the open-end spinning device at full speed at this point, there is no jump in speed, so that there is no risk of thread breaks at this point either.

In order to compensate for the different coil diameters and the consequent different coil entrainment, it is advantageously provided that the contact pressure between the coil and the coil drive is increased with increasing coil diameter.

It is expediently provided that the start-up of the thread draw-off is accelerated more gently with a smaller amount of fiber effective in the open-end spinning device and more strongly with a larger amount of fiber effective in the open-end spinning device. As a result, less fiber material is required in the open-end spinning device at the moment the thread take-off is inserted, i.e. the dwell time between the end of the return delivery and the start of the thread take-off can be kept shorter, so that the excessive amount of fibers otherwise leading to a thick point in the thread thickness in the open-end spinning station can be avoided, while at the same time the yarn strength due to the correct rotation propagation in the open-end spinning device does not fall off compared to the thread piecings previously produced in the usual way.

According to a particularly advantageous method, the pressure roller of the pair of draw-off rollers is lifted off the driven roller before the re-spinning, the thread is presented to the draw-off tube after being cut to length, so that the thread takes a curved course over the driven roller, and is put back on to insert the normal spinning take-off, when the bobbin has reached the full winding speed. In this way, a precise and gentle insertion of the thread take-off can be achieved, wherein control of the pressure roller from a maintenance device, which can be moved along a large number of open-end spinning stations, enables a particularly economical device.

It is preferably provided for piecing that the pressure roller of the draw-off roller pair is lifted from the driven roller, that the bobbin is also released from the main drive, that the thread is then pulled off of the bobbin while being turned back, guided over a throwing-off device, to a defined length Then the trimmed thread end is brought in front of the mouth of the thread take-off tube and thereby gets between the driven roller and the pressure roller of the pair of draw-off rollers and is then returned to the ready position in the thread take-off tube, whereupon the throwing-off device throws off the thread, which is now caused by the negative pressure prevailing in the spinning device the fiber collecting surface is supplied, that the newly spun thread is then drawn off the fiber collecting surface with increasing speed and that finally, after reaching the full winding speed, the bobbin is lowered onto the main drive d the pressure roller is placed back on the driven roller of the pair of draw rollers. This not only enables safe spinning regardless of the respective spinning conditions, but also a controlled and gentle retraction of the newly spun thread.

To carry out the method, according to the invention, a length measuring device that can be adjusted to the diameter of the fiber collecting surface is provided for returning the thread end to a standby position, and a thread ejecting element that is arranged between the spinning device and the bobbin and deflects the thread. The purpose of the length measuring device is to bring the thread into a predetermined ready position, while the throwing device enables the thread to come into contact with the fibers fed to the open-end spinning device. The length measuring device can be adjusted to the respectively selected diameter of the fiber collecting surface of the spinning element in order to always provide constant piecing returns through the thread-pulling device and thus also constant piecing conditions, even if the open-end spinning device can be operated with fiber collecting surfaces of different diameters.

In order to enable the rotation occurring in the piecing phase to be distributed over a greater length of the thread, in an advantageous embodiment of the subject matter of the invention an auxiliary take-off device is provided, which is arranged at a greater distance from the open-end spinning device than the pair of take-off rolls. This enables piecing at particularly high speeds of the spinning element.

According to an expedient embodiment of the subject matter of the invention, the auxiliary draw-off device is designed as a pair of auxiliary draw-off rollers, which is particularly advantageous in connection with a thread-connecting device replacing the piecing device, which is why, in a further embodiment of the subject-matter of the invention, a thread-connecting device can be brought into the thread path between the pair of draw-off rollers and the pair of auxiliary draw-off rollers.

According to a preferred embodiment of the subject matter of the invention, the auxiliary take-off device is formed by the coil and a drive roller which can be driven in both directions of rotation, the drive of the drive roller being expediently adjustable in adaptation to the start of the fiber feed effective in the open-end spinning device. This device makes it possible to run the thread draw up to full speed in such a way that speed jumps are avoided, so that there is no risk of thread breaks.

To avoid strong indentations, it can According to the invention, the drive roller wears a jacket made of a soft material, preferably soft rubber.

The measure that a pressure device is assigned to the drive roller, by means of which the drive roller is pressed against the coil with increasing coil diameter with increasing contact pressure, can ensure that the same coil acceleration is always achieved regardless of the coil diameter.

If it is provided that the drive roller is pressed against the spool on the side facing away from the spooling roller, then depending on the size of the spool, different positions of the drive roller are obtained when driving the spool, so that the instantaneous diameter of the spool has an effect.

A compact design of the auxiliary coil drive is achieved according to the invention in that the drive roller is carried by a swivel arm on which a torsion spring acts. By appropriate selection of the characteristics of the spring constants, dimensions and pretension, the same piecing ratios can always be achieved regardless of the coil diameter.

In order to be able to control various elements working during piecing from one and the same drive, it is provided according to a further feature of the invention that the drive roller is carried by a swivel arm, the drive of which has a rotatable cam disk and an adjustable intermediate linkage between the cam disk and swivel arm. The intermediate linkage enables the swivel arm to be adjusted in a particularly simple manner.

Advantageously, a lifting element is provided which can be inserted between the winding roller and the bobbin, and a support device which can be brought into action on the bobbin arms and which, after the lifting element has been withdrawn, ensures a constant distance between the peripheral surface of the bobbin and the winding roller. As a result, the bobbin is immediately lifted off the winding roller when a thread break occurs. This can happen so quickly that the end of the broken thread no longer reaches the bobbin and hangs freely from the bobbin. It is particularly easy to pick up the thread for the return delivery. But even if the thread comes onto the bobbin, it can easily be picked up here when the bobbin is later turned back, since the rapid stoppage of the bobbin prevents the thread from being rolled tightly into the bobbin. The lifting element is designed so that a defined distance is formed between the spool and the winding roller, so that the instantaneous diameter of the spool affects the working position of the drive roller, which cooperates with the side of the spool facing away from the spool.

In a preferred mechano-electrical embodiment of the subject matter of the invention, the support device has a drive lever which can be pivoted by a controllable drive, and a support lever which is arranged thereon and can be pivoted between two end positions and which is acted upon by an elastic element in the direction of the coil and thereby into its first end position and at Heading onto one of the two coil arms can be brought into its second end position, which is assigned a switching device for ending the pivoting movement of the drive lever. In such an embodiment of the device according to the invention, a switching device is actuated mechanically. In addition, with the aid of the aforementioned device according to the invention it is achieved that, despite different positions of the coil arms, these are always supported by the support device in such a way that the same distance between the peripheral surfaces of the coil and the main drive roller is ensured, so that the lifting element is withdrawn and the support function can be left to the support device. The end position of the support lever is expediently determined by two stops attached to the drive lever. According to a preferred embodiment of the subject matter of the invention, the controllable drive for the drive lever is designed as an electric motor and the switching device is designed as an electrical switch arranged on the drive lever, which interrupts the power supply to the motor when actuated by the support lever.

In an open-end spinning machine with a large number of open-end spinning devices, a design is particularly advantageous in accordance with which the pressure roller, which can be lifted off from the driven take-off roller by a maintenance device which can be moved along a large number of open-end spinning devices, and can be put back on the driven take-off roller. In this way, an inexpensive device suitable for piecing according to the invention can be created.

The subject of the registration creates the conditions for the reliable spinning even at high rotor speeds, so that an exact timing of the attachment process to the run-up curve of the spinning rotor is not necessary. This results in a significant simplification of the control, which allows large time tolerances and is therefore easy to master.

• Figur 1 den Erfindungsgegenstand in schematischer Seitenansicht,
• Figur 2 eine Abwandlung eines Details der in Figur 1 gezeigten Vorrichtung in der Draufsicht, und
• Figur 3 und 4 eine weitere Abwandlung des Erfindungsgegenstandes in zwei verschiedenen Arbeitsphasen in schematischer Seitenansicht.

Further advantages and details of the invention are explained on the basis of the following description and several exemplary embodiments illustrated in the drawings. It draw:

• FIG. 1 shows the subject of the invention in a schematic side view,
• Figure 2 shows a modification of a detail of the device shown in Figure 1 in plan view, and
• Figures 3 and 4 a further modification of the subject of the invention in two different work phases in a schematic side view.

First, the device and the method are explained with reference to FIG. 1. This figure shows the essential parts of a spinning machine 1 operating according to the open-end spinning process, insofar as they are necessary to understand the explanation. These parts are in In practice, it is usually distributed to the spinning machine 1 and a maintenance device 2 which can be moved along the spinning machine 1, but it is also possible to provide all the elements shown on the spinning machine 1 itself and to dispense with the maintenance device 2, in particular in the case of test machines with one or only few spinning positions.

The spinning machine 1 shown has a large number of spinning positions, of which FIG. 1 only shows one spinning position. An open-end spinning device with a spinning element arranged in a housing 10, a pair of take-off rollers 13 and a winding device 30 are provided for each spinning station. In the embodiment shown, a spinning rotor 11 is used, for example, as the spinning element, which generates a thread 3 which, after incorporation in the usual manner, with the aid of a fiber delivery device and a dissolving device - e.g. in the form of an opening roller - the fibers fed to the spinning element are drawn off from the housing 10 by means of the pair of draw-off rollers 13 through a draw-off tube 12. A thread monitor 36 is arranged in the thread path between the housing 10 and the pair of draw-off rollers 13.

To wind the thread 3, the spinning machine 1 has a winding device 30, which essentially has a main drive roller 31 for driving the bobbin 33, which is interchangeably received by two pivotable bobbin arms 32. The coil arms 32 are pivotable about an axis 34.

In order to compensate for the thread tension fluctuating during the traversing of the thread 3, a thread tension compensation bracket 14 is arranged in a known manner in the thread path between the draw-off roller pair 13 and the bobbin 33.

On the spinning machine 1, a part of a spool lifting device 4 forming lifting element 40 is also provided per spinning station, which lifts the latter by a certain value a from the main driving roller 31 by being inserted between the main drive roller 31, so that a due to the strength of the lifting element 40 Defined distance a between the peripheral surfaces of the coil 33 and the main drive roller 31 is formed.

A suction pipe 20 is arranged on the maintenance device 2 and can be brought to the underside of the bobbin 33 lifted off the main drive roller 31 in order to be able to pick up the end of a broken thread 3 there. The suction tube 20 has a cranked shape and has a longitudinal slot (not shown) on its side facing the spinning machine 1, so that the thread 3 can partially leave this slot in the form of a chord as it enters the suction tube 20.

The maintenance device 2 also carries a pair of auxiliary rollers 21 which is supported by a lever 23 which can be pivoted about an axis 22 such that the pair of auxiliary rollers 21 can grip the thread 3 arranged tendon-like to the suction tube 20 and feed it to the draw-off tube 12.

In addition, a coil auxiliary drive 5 is arranged on the maintenance device 2. The coil auxiliary drive 5 has a swivel arm 50 which is pivotably mounted on an axis 51 and carries a roller 52 at its free end, which can be driven in a manner not shown by a drive, not shown, in either direction. The roller 52 is surrounded by a jacket 53 made of soft rubber or another soft material.

A swivel drive 6 for the swivel arm 50 is further arranged on the maintenance device 2, which in the embodiment shown has a camshaft 61 driven by a motor 60, on which a cam disk 62 is arranged. On an axis 63 carried by the maintenance device 2, a two-armed lever 64 is pivotably mounted, at one end of which the cam disk 62 can engage and at the other end of which an actuator 65 is connected. This actuator 65, the free end of which is connected to the swivel arm 50, consists in the embodiment shown of two bolts 66 and 67, which have opposite threads and on which a threaded sleeve 68 is screwed with opposite threads, so that by rotating the threaded sleeve 68 Distance between the lever 64 and the pivot arm 50 can be changed. In this way, a precise adjustment of the lever 64 to the swivel arm 50 is possible. The cam plate 62 causes the roller 52 to be lifted off the spool 33, while a tension spring 7 acting on the swivel arm 50 causes the swivel arm 50 to be supported on the spool 33 by the cam plate 62 when the lever 64 is released.

An additional arm 35 is attached to the coil arm 32, with which a support device 8 can cooperate. In the embodiment shown, the support device 8 consists essentially of a pivotably mounted drive lever 80, on the free end of which a support lever 81 is articulated. This two-armed support lever 81 is movable between two stops 82 and 83 attached to the drive lever 80 and is acted upon by means of an elastic element designed as a compression spring 84, which is supported at one end on the drive lever 80 and at the other end on the support lever 81, so that the support lever 81 is normally supported on the stop 82. A switch 85 is provided on the drive lever 80 so that the support lever 81 actuates this switch 85 when it rests against the stop 83 without being supported on the switch housing. The switch 85 is electrically connected to a motor 86 which serves as a pivot drive for the drive lever 80 and secures the drive lever 80 in its current position when it is stopped. The motor 86 is connected to a control device 9, which is also connected to the motor 60.

The device described above in construction works as follows:

If a thread break occurs, this triggers the termination of the fiber supply in the spinning rotor 11 and a lifting of the bobbin 33 from the main drive roller 31 by the thread monitor 36 by the fact that the essential component of the bobbin lifting device 4 lifting element 40 between rule coil 33 and main drive roller 31 is pushed. The winding of the thread 3 on the bobbin 33 is thus interrupted extremely quickly, depending on the winding speed, often even before the end of the thread has reached the bobbin 33. By inserting the lifting element 40 between the main drive roller 31 and the coil 33, the coil lifting device 4 forms a precisely defined distance a between the peripheral surfaces of the coil 33 and the main drive roller 31, this distance corresponding to the thickness of the lifting element 40 between the coil 33 and the main drive roller 31.

As a result of the opening roller (not shown) that continues to run even after the fiber delivery device is stopped, the fiber beard projecting into the working area of the opening roller is milled off and fed to the spinning rotor 11 together with the fibers in the clothing of the opening roller.

From the thread monitor 36 mentioned, a signal is triggered in a known manner, which either causes the maintenance device 2 or which causes the continuously rotating maintenance device 2 to stop at the disturbed spinning position in order to remedy the broken thread.

When the maintenance device 2 has assumed its working position at the spinning position concerned, a control device 9 temporarily switches on a rotor cleaning device (not shown), as a result of which the fibers in the spinning rotor 11 are removed from it in a manner known per se. Furthermore, in a manner not shown, the maintenance device 2 lifts the pressure roller of the pair of draw-off rollers 13 from the driven roller. In addition, the drive lever 80 is pivoted upward with the support lever 81 with the aid of the motor 86. During this movement, the support lever 81 resting on the stop 82 comes to rest against the arm 35 of the spool arm 32. As a result, the support lever 81 is pivoted relative to the drive lever 80 against the action of the compression spring 84 until it bears against the stop 83. In this position, the support lever 81 actuates the switch 85, which thereby opens and thus interrupts the power supply to the motor 86. The lifting movement of the drive lever 80 is thus ended and this lever is fixed in the current position. Now the control device 9 causes the lifting element 40 to be withdrawn so that it releases the coil 33. This can be done by mechanical action from the maintenance device 2 on the lifting element 40 or by actuation of an electrical element, not shown, which brings about this relationship. Despite the retraction of the lifting element 40, however, the spool 33 remains in its current position since it is supported by the support lever 81.

After release of the bobbin 33 by the lifting element 40, the control device 9, in a manner not shown, causes the suction tube 20 to be brought into the thread take-up position. In this position, the suction tube 20 is located on the underside of the coil 33, so that the distance between the suction tube 20 and the coil 33 is essentially the same regardless of the coil diameter. In addition, the control device 9 switches on the motor 60, which causes the camshaft 61 to rotate. In this way, the cam disk 62 releases the lever 64, so that the roller 52 is brought into contact with the coil 33 by the action of the tension spring 7 on the swivel arm 50. Depending on the size of the coil 33, the tension spring 7 is more or less tensioned so that with a larger coil diameter the contact pressure of the roller 52 with the coil 33 is greater than with a smaller coil diameter. If the roller 52 is now driven via return means (not shown) for returning the thread 3, this different contact pressure compensates for the inertia and avoids a different slip which would otherwise occur due to the different masses of the bobbin 33.

During the turning back of the bobbin 33, the thread 3, which lies only loosely on the circumference of the bobbin due to the rapid stopping of the bobbin 33 with the aid of the lifting element 40, is sucked into the suction tube 20, and during the suctioning it is due to the cranked shape of the suction tube 20 in the form of a tendon partially exits from the suction pipe 20. After a sufficient length of thread has reached the suction tube 20, the return delivery of the thread 3 is interrupted by control from the control device 9 and the suction tube 20 is brought into its position shown in broken lines. Subsequently, the auxiliary roller pair 21 is pivoted out of a rest position about the axis 22, this auxiliary roller pair 21 passing through the course of the thread 3 entering the slot of the suction tube 20. The thread on the side of the auxiliary roller pair 21 facing away from the bobbin 33 is separated by conventional means, not shown, and the auxiliary roller pair is pivoted in front of the mouth of the draw-off tube 12. The spinning rotor 11 or another open-end spinning element has meanwhile been rotated again and the fiber feed on the fiber collecting surface has been switched on again. In a suitable timing, the thread 3 is returned again by rotating the bobbin 33 and the pair of auxiliary rollers 21 until it reaches the fiber collecting surface of the spinning rotor 11 or another open-end spinning element, whereupon the clamping of the auxiliary roller pair 21 is released, for example by lifting the further from the roller 22 arranged from the roller closer to the axis 22. As a result, the thread 3 is released from the auxiliary roller pair 21. The auxiliary roller pair 21 now returns to its rest position. After the thread 3 has been released by the auxiliary roller pair 21, the roller 52 is driven in the opposite direction, so that the thread 3 is drawn off from the spinning rotor 11. The thread 3 is thus drawn off from the spinning rotor 11 exclusively by the bobbin 33 in this piecing phase.

As described, the drive of the fiber delivery device is switched on at a moment which is coordinated with the return delivery and renewed removal of the thread 3. Since the previously empty clothing of the opening roller must first be filled again until the full fiber flow into the spinning rotor 11 long, with regard to the spinning rotor 11 there is a soft effect of the fiber delivery. In accordance with this effect of the fiber delivery, the thread draw-off should also become "soft" in order to ensure a piecing of high strength and, on the other hand, to avoid an excessively large jump in the thread tension and thus thread breaks. The roller 52 is thus accelerated to the normal winding speed in a relationship which is adapted to the effect of the fiber delivery in the spinning rotor 11, the inevitable slippage of the coil 33 being taken into account when the roller 52 is accelerated. As mentioned, the slip is kept by the choice of an appropriate spring constant, length and tension of the tension spring 7 regardless of the respective bobbin diameter in such a way that it does not or only falsifies the thread take-off speed within tolerable limits. When the bobbin 33 has reached the full bobbin winding speed, the bobbin 33 is lowered by pivoting the drive lever 80 onto the main drive roller 31 and the roller 52 is lifted off the bobbin 33 by the action of the cam disk 62 on the lever 64. Furthermore, the pressure roller of the pair of draw rollers 13 is released by the maintenance device 2. Thus, if the thread monitor 36 does not indicate that the thread break repair has failed, the thread is drawn off and the thread 3 is wound onto the bobbin 33 again independently of the maintenance device 2 by the spinning machine 1 itself. The thread breakage elimination, all of whose work steps are controlled by the control device 9 of the maintenance device 2, is thus completed.

The described method is not restricted to the exemplary embodiment shown. The device can also experience modifications in the context of technical equivalents or other combinations of features.

As mentioned, the auxiliary roller pair 21 is assigned a thread separation device in the usual way, which brings the thread 3 to a certain length. In addition, a return delivery measuring device is assigned to the auxiliary roller pair 21 in a known manner, which determines the number of rotations of the auxiliary roller pair 21 and thus the return delivery amount of the thread 3.

As shown in FIG. 1 in a broken line, a throwing member 25 deflecting the thread 3 can be provided in the thread path between the pair of draw-off rollers 13 and the bobbin 33.

When the thread 3 is sucked out of the bobbin 33, the thread 3 arrives at the ejection element 25. When the thread 3 is subsequently fed to the draw-off tube 12 with the aid of the auxiliary roller pair 21 and cut to a predetermined size, the thread 3 takes a curved course . By the mentioned return delivery measuring device - which is designed, for example, as a timing element that controls the duration of the current supply to the drive motor of the auxiliary roller pair 21 - the auxiliary roller pair 21 is driven by a predetermined number of rotations in the return delivery direction. As a result, the thread end in the thread take-off tube 12 reaches a precisely defined position, which is identified in FIG. 1 as position B ₁ . In this position Bi, the thread end is between the two ends of the thread take-off tube 12, where it is held securely by the negative pressure acting in the spinning device. This position Bi is selected so that its distance along the thread take-off path is essentially the same as the additional thread path that results from the deflection by the take-off member 25 compared to the normal thread path between the take-off roller pair 13 and the bobbin 33.

The pair of auxiliary rollers 21 now releases the thread 3 and can thus be pivoted away from the area of the mouth of the draw-off tube 12. For spinning, the throwing member 25 now throws off the thread 3, the end of which comes from the ready position B ₁ to the area of the fiber collecting surface of the spinning rotor 11 chosen as an example, where it integrates the fibers that have now been fed in. The piecing take-off by the bobbin 33 now begins in time with the thread dropping by the throwing member 25.

As already mentioned, the released thread length has essentially the same length as the distance from the standby position B ₁ along the thread withdrawal path from the collecting surface - ie collecting groove of the spinning rotor 11 - is; However, it must be taken into account in the thrown-off thread reserve that the thread end must be able to lay down in the collecting groove of the spinning rotor over a certain length of the circumference in order to break open and bind in the fiber ring. By releasing the thread 3 both by the pair of auxiliary rollers 21 and by the throwing member 25, the thread 3 is returned to the spinning rotor 11 solely by the negative pressure acting in the open-end spinning device. Depending on the properties of the thread 3, this return delivery takes place at different speeds, and it has been shown that threads that can take up a higher rotation before it comes to twist in the spinning rotor 11 follow this vacuum more quickly than threads that are less elastic and therefore more tend to overturn and twist off. This results in a certain automatic adaptation of the piecing process to the yarn properties, which increases piecing reliability.

In open-end spinning machines, in which spinning elements with different diameters of their collecting surfaces can be used, it is provided that the return delivery measuring device can be adjusted depending on the diameter selected in each case. If, for example, the return delivery measuring device is designed as a digitally adjustable time relay, it is sufficient to specify the corresponding time as a digital value in accordance with the selected diameter, as a result of which the working time of the drive motor for the auxiliary roller pair 21 and thus also the return delivery path of the thread 3 is determined.

A spinning rotor 110 is shown in dashed lines in FIG. 1 and has a larger diameter than the spinning rotor 11. So regardless of this diameter, the same path of the piecing back achieved by the ejector 25 Delivery can be provided, the timing relay is adjusted to a larger rotor diameter adapted to the higher time, so that the auxiliary roller pair 21 delivers the thread 3 to the standby position B ₂ . Here too, the actual piecing return is carried out by the described ejection device 25.

In principle, it is not necessary for the throwing member 25 to get into its working position before the thread 3 is returned by the auxiliary roller pair 21, but this saves a return delivery from the bobbin 33 that is synchronized with the build-up of the thread reserve by the throwing member 25, which is necessary , if the ejector 25 builds up the reserve length at a later time.

As described above, it is essential for the method that during the piecing phase the twist can temporarily propagate further from the thread section in which the twist takes place than during the normal spinning process into the part of the thread 3 facing away from the spinning rotor 11. For this purpose, it is necessary to keep the forces that could cause a twist stop smaller on the side of the thread section mentioned facing the bobbin 33 than on the side of this thread section facing the spinning rotor 11 and as far as possible in relation to the bobbin 33 to postpone. This can be done by eliminating deflection points for the thread 3 during the piecing phase or at least weakening them so that they do not form a rotation stop. This can e.g. take place so that the take-off roller pair 13 or their driven roller is pivoted away from the thread path during piecing. If by lifting the pressure roller from the driven roller of the Ab-. tension roller pair 13 the thread clamping is released, the rotation in the direction of the spool can propagate almost unhindered, while the propagation of rotation in the spinning rotor 11 is made more difficult by the deflection edge at the mouth of the draw-off tube 12 facing the spinning rotor 11.

In the embodiment described above, the auxiliary trigger for the piecing process takes place exclusively by individually driving the coil 33, but it is also conceivable to make this auxiliary trigger independently of the coil 33. For example, an additional pair of auxiliary take-off rollers 900 can be brought into the thread path in the vicinity of the bobbin 33 for the piecing take-off from the maintenance device 2. However, pulling off the thread 3 in the piecing phase exclusively by the bobbin 33 is particularly advantageous, since in this way no additional elements are required for the piecing draw-off, but a corresponding choice of the elastic element, for example, designed as a tension spring 7, is sufficient for this.

Such a modification with a pair of auxiliary take-off rollers 900 is described below with reference to FIGS. 3 and 4. Since such an embodiment is particularly expedient if it is used in connection with a thread connecting device 97 (e.g. knotter, splicing device, etc.), with the aid of which the thread connection (piecing) produced during piecing is replaced by another type of thread connection, this is used Modification described in connection with such a thread connecting device 97.

The auxiliary take-off roller pair 900 - which is provided on the side of the take-off roller pair 13 facing away from the spinning rotor 11 - is located in the exemplary embodiment shown, like the various elements described below, on the maintenance device 2 and can be brought into its working position if necessary. The thread 3 is inserted into the pair of auxiliary draw-off rollers, if this is in the vicinity of the course of the thread sucked into the suction tube 20, with the aid of means not shown and customary for such purposes. On the side of the auxiliary take-off roller pair 900 facing away from the spinning rotor 11, the mouth 91 of a thread suction device 90 can be brought into the thread run so that it can take up the excess thread when the tension in the thread section between the auxiliary take-off roller pair 900 and the bobbin 33 decreases. A cutting device 92 is assigned to the mouth 91 of this thread suction device 90 and can be controlled in a suitable manner. In the embodiment shown, the cutting device 92 is arranged on an arm 94 which can be pivoted about an axis 93, but it is also possible to fasten this device to the thread suction device 90 in front of the mouth 91. On the side of the cutting device 92 facing away from the mouth 91 there is also a thread clamp 95 which, in the embodiment shown, is actuated together with the cutting device 92 with the aid of an electromagnet 96.

The thread connection device 97 already mentioned and designed, for example, as a knotter, is arranged in the thread run between the pair of draw-off rollers 13 and the auxiliary draw-off roller pair 900. A thread storage device 98 is located between the pair of draw-off rollers 13 and the thread-connecting device 97. Furthermore, a deflection member 99 is provided between the thread-connecting device 97 and the auxiliary draw-off roller pair 900, which keeps the thread extending to the bobbin 33 together with a suction nozzle 24 on a precisely defined thread path. This suction nozzle 24 can be brought into the position shown in FIG. 4 from a thread take-up position in which it receives the thread section extending from the bobbin 33 to the thread clamp 95.

The device shown in Figures 3 and 4 operates as follows:

If a thread break occurs, the open-end spinning device in question is stopped and the maintenance device 2 is brought into the piecing position, as was discussed using the example in FIG. 1. The preparation and suction of the thread 3 into the suction tube 20 also take place in the manner described. If a sufficient length of thread goes into the suction pipe 20 was sucked, so that it is ensured that the thread 3 is held securely by the suction tube 20, the thread 3 is inserted by conventional means, not shown, into the clamping line of the auxiliary take-off roller pair 900 located near the thread run. The thread still unwound by turning back the bobbin 33 is now taken up by the mouth 91 of the thread suction device 90 located in the vicinity of the thread path between the bobbin 33 and the auxiliary drawing roller pair 900 and is sucked off in the form of a loop 37. As soon as a thread length sufficient for spinning has been sucked into the thread suction device 90, the bobbin 33 is stopped and the thread 38 between the bobbin 33 and the mouth 91 is cut with the aid of the cutting device 92 and held by the thread clamp 95.

The suction nozzle 24 is now brought into the area of the thread path between the bobbin 33 and the thread clamp 95. The backward rotation of the coil 33 is continued. The thread clamp 95 releases the thread 38, which is now taken up by the suction nozzle 24. If the thread length taken up by the suction nozzle 24 ensures that the thread 38 is held securely even when the suction nozzle 24 is pivoted, it is brought into a position shortly after the pair of take-off rollers 13 - viewed in the direction of thread take-off from the thread take-off tube 12. The thread deflecting element 99 is then pivoted into the course of the thread between the bobbin 33 and the suction nozzle 24, as a result of which the thread 38 is deflected.

Irrespective of this, the thread 3, which extends from the thread suction device 90 to the suction tube 20 and is inserted into the auxiliary take-off roller pair 900, is picked up by the auxiliary roller pair 21, brought to the length required for piecing and fed to the suction tube 12. The auxiliary roller pair 21 and the auxiliary take-off roller pair 900 are now turned back simultaneously and synchronously, so that the thread 3 is returned to the spinning rotor 11. Then the clamping of the auxiliary roller pair 21 is released, whereupon this auxiliary roller pair 21 can return to its starting position. However, the clamping of the auxiliary take-off roller pair 900, whose direction of rotation is now reversed, is maintained. By reversing the direction of rotation of this auxiliary take-off roller pair 900, the thread 3 is withdrawn again from the spinning rotor 11. The thread 3 is fed to the thread suction device 90, which receives the spun thread 3.

Just as with the take-off take-off by the bobbin 33, the thread 3 is released over a very long length in the take-up phase. The rotations in the thread 3 generated by the spinning rotor 11 rotating at full speed can thus be distributed over a long length, so that the resistance to the propagation of rotation down to the collecting surface (collecting groove), which is caused by the thread deflection at the mouth of the spinning rotor 11 Thread take-off tube 12 is generated, a substantially longer time is sufficient to prevent excessive rotation in the thread section located in the spinning rotor 11. Depending on the size of the distance of the auxiliary take-off roller pair 900 from the thread take-off tube 12, a more or less high speed of the spinning rotor 11 can be selected within certain maximum limits.

The suction nozzle 24 and the deflection element 99 assume such a position with respect to the course of the thread drawn out of the spinning rotor 11 by the auxiliary take-off roller pair 900 that the thread section between the suction nozzle 24 and the deflection element 99 runs essentially parallel to the thread section between the thread take-off tube 12 and the auxiliary take-off roller pair 900 . The coil 33 is now stopped.

The thread store 98 is then pivoted into the course of the thread drawn out of the thread take-off tube 12 by the auxiliary take-off roller pair 900. The thread connecting device 97 is then brought into the course of the threads 3 and 38. While the thread connection process is being carried out, both threads 3 and 38 must be stopped in its working area. This is done in that the thread quantity supplied by the spinning rotor 11 is temporarily stored by the thread store 98, while the thread 38 is not moved anyway by stopping the bobbin 33. In the course of the thread connection process, the two threads extending to the thread suction device 90 and to the suction nozzle 24 are cut off and removed.

After the thread connection process has ended, the thread connecting device 97 releases the thread which now extends again from the spinning rotor 11 to the bobbin. The bobbin 33 is lowered onto the main drive roller 31 and driven again by it, the thread store 98 gradually being emptied again. The deflecting element 99 now also releases the thread again, so that it resumes the thread path customary for production.

If the device described with reference to FIGS. 3 and 4 is to be used without the piecing device being replaced by another type of thread connection, the cutting device 92 and the thread clamp 95 are not actuated. Simultaneously with the insertion of the piecing take-off by the auxiliary take-off roller pair 900 or shortly thereafter, the bobbin 33 is brought back into contact with the main drive roller 31 and the thread is released from the auxiliary take-off roller pair 900 in a manner known per se in a manner known per se.

At low working speeds, the run-up speed can be freely selected; at high thread take-off speeds, however, it is expedient for the reasons already described if the run-up curve is adapted to the run-up curve of the fiber feed effective in the spinning rotor 11.

When driving an auxiliary take-off roller pair 900 according to FIGS. 3 and 4, maintaining a certain run-up curve is not a problem, since the masses to be driven of this roller pair are always constant.

In order for the piecing take-off through the coil 33 de To achieve defined slip ratios, it is necessary that separate devices are provided for lifting the spool 33 from the main drive roller 31 and for driving the spool. In principle, it is possible that the bobbin lifting device 4 engages the bobbin arm 32 or an arm 35 attached to it and at the same time forms the support device 8, ie holds the bobbin 33 with its imaginary axis during the entire thread breakage elimination in a certain lifting position. Here, too, the position of the swivel arm 50 of the auxiliary coil drive 5 changes in accordance with the coil size, so that the tension spring 7 also generates a different roller pressing force depending on the coil diameter. However, with such a design, only the radius of the coil 33, that is to say half its diameter, has an effect on the tension spring 7.

If the coil 33 is assigned a light barrier monitoring, it can also be used to lift the coil 33 so that the distance a between the circumference of the coil 33 and the circumference of the main drive roller 31 is always the same regardless of the coil diameter. In this way, as in the exemplary embodiment described with reference to FIG. 1, the entire diameter of the coil 33 can be used for changing the spring tension.

Such light barrier monitoring can also be used when a support device 8 is provided, but does not have separate drive and support levers.

If a support device 8 is provided with a separate drive and support lever (80 and 81), a switching device is provided, which in the embodiment shown is designed as a switch 85. If desired, a shift linkage can also be provided in its place, which causes the drive lever 80 to be uncoupled from the motor 86 and fixed in its current position (for example with the aid of a pawl). The stops 82 and 83 can either be arranged on the drive lever 80 or on the support lever 81 or can be divided between the two levers.

The support device 8 does not have to be supported on an additional arm 35 of the coil arm 32, but can also engage the same or an extension thereof.

The design of the elastic element assigned to the swivel arm 50 can also differ from the illustration. So it is quite possible to provide a hydraulic or pneumatic piston instead of a spring. Instead of a tension spring 7, a compression spring can also be used. FIG. 2 shows a further modification of the device, in which a torsion spring 70 is provided, one leg 71 of which is supported on the swivel arm 50 and the other leg 72 of which is supported on a bearing 54 which receives the axis 51 of the swivel arm 50. As Figure 2 shows, such an embodiment is particularly compact.

The roller 52 in the embodiment described has a jacket 53 made of soft rubber or another material. This results in an enlargement of the contact surface of the roller 52 on the spool 33, since the jacket 53 seeks to laterally avoid the contact pressure acting on it. The roller 52 can even have a smooth surface despite good drive entrainment, so that the material wound on the spool 33 is treated gently in comparison with, for example, an all-metal roller with a corrugation or the like provided on the circumference, which of course also is possible.

The various elements - such as intake manifold 20, swivel arm 50 and drive lever 80 or the elements not shown - can be driven in various ways, for example with the aid of pneumatic or hydraulic pistons. The design shown with an adjustable intermediate linkage 64, 65, 66, 67, 68 is particularly advantageous if the engine 60 drives various cam disks 62 via the camshaft 61, for example for the movement of the suction tube 20 and / or for the pivoting of the auxiliary roller pair 21 and / or for lifting the pressure roller from the driven roller of the pair of take-off rollers 13. In this case, the intermediate linkage 64, 65, 66, 67, 68 enables the individual drives to be adapted to the working conditions in a particularly simple manner, in particular if the dimensions are as equal as possible the individual parts of this intermediate linkage are to be provided.

It is also possible to provide a different direction of the material flow, the working elements being to be provided in a correspondingly adapted arrangement which differs from the drawing.

Claims (29)

1. Method for joining a thread in an open-end spinning apparatus, in which the thread is drawn off of a bobbin, is cut to a defined length, and the thread end is brought, while forming a thread reserve, into a position for introducing it into the spinning apparatus, and the thread end is delivered back from the thread reserve into the spinning apparatus and the newly joined thread is drawn off, characterized in that, from the position for introduction into the spinning apparatus, first of all the thread end is brought into a readiness position inside the thread draw-off tube, from which the thread end is returned as far as the fibre collecting surface by releasing the thread reserve.

2. Method according to claim 1, characterized in that the drawoff process of the newly joined thread begins, with respect to the releasing of the thread reserve, at a definable period of time.

3. Method according to claims 1 or 2, characterized in that the thread by cutting is brought to a length such that the thread end which, while forming the thread reserve needed for the back-delivery from the readiness position, is fed as far as to the area in front of the thread draw-off tube, and by newly back-delivering from the bobbin by a predetermined distance is brought into the readiness position.

4. Method according to claim 3 characterized in that the distance is predetermined in dependence upon the diameter of the fibre collecting surface of the open-end spinning apparatus.

5. Method according to one or more of claims 1 to 4, characterized in that releasing of the thread reserve is realised by throwing-off the thread.

6. Method according to one or more of claims 1 to 5, characterized in that, after termination of the thread backdelivery until the beginning of the normal spinning draw-off process, the thread is subjected to an auxiliary draw-off process at a greater distance from the open-end spinning apparatus than this spinning draw-off process.

7. Method according to claim 6, characterised in that the auxiliary draw-off process occurs independently of the winding of the thread.

8. Method according to claim 6, characterized in that the auxiliary draw-off process occurs exclusively by means of the bobbin.

9. Method according to claim 8, characterized in that the contact pressure between bobbin and bobbin drive is increased as the bobbin diameter increases.

10. Method according to one or more of claims 6 to 9, characterized in that the running-up of the thread draw-off is accelerated more softly when a smaller amount of fibres is effective in the open-end spinning apparatus and more vigorously when a greater amount of fibres is effective in the open-end spinning apparatus.

11. Method according to one or more of claims 1 to 10, for joining a thread in an open-end spinning apparatus having a pair of draw-off rollers with a pressure roller and a driven roller, characterized in that before joining the pressure roller of the pair of draw-off rollers is lifted off of the driven roller, in that the thread after having been cut to a defined length is presented to the draw-off tube so that the thread has a curved path over the driven roller, and in that the pressure roller is again brought to contact the driven roller for initiating the normal spinning draw-off process when the bobbin has reached the full winding speed.

12. Method according to claim 11, characterized in that the pressure roller is controlled by a servicing apparatus which may be moved along a plurality of open-end spinning devices.

13. Method according to one or more of claims 1 to 12, for joining a thread in an open-end spinning apparatus, having a pair of draw-off rollers with a pressure roller and a driven roller, a main drive for the bobbin as well as a throw-off member, characterized in that the pressure roller of the pair of draw-off roller is lifted off of the driven roller, in that further on the bobbin is released by the main drive, in that thereafter the thread by simultaneously back-rotating the bobbin is drawn off therefrom, guided via a throw-off member, brought to a defined length, in that then the cut thread end is brought into the area in front of the thread draw-off tube and thereby comes to lie between the driven roller and the pressure roller of the pair of draw-off rollers and is thereafter returned into the readiness position in the thread draw-off tube whereupon the throw-off member throws off the thread which now is fed to the fibre collecting surface by means of the underpressure existing in the spinning apparatus, in that subsequently the newly spun thread is drawn off the fibre collecting surface with increasing speed and in that finally, after the bobbin has reached the full winding speed, the bobbin is lowered to contact the main drive and the pressure roller is again put onto the driven roller of the pair of draw-off rollers.

14. Apparatus for performing the method as claimed in one or more of claims 1 to 13, characterized by a length measuring apparatus for returning the thread end into a readiness position which apparatus is adjustable to the diameter of the fibre collection surface, and a thread throw-off member (25) which is disposed between the spinning apparatus and the bobbin (33) and deflects the thread (3).

15. Apparatus according to claim 14, characterized by an auxiliary draw-off apparatus (33, 900) being arranged at a greater distance from the open-end spinning apparatus (10, 11) than the pair of draw- off rollers (13).

16. Apparatus according to claim 15, characterized in that the auxiliary draw-off apparatus is formed by an auxiliary pair of draw-off rollers (900).

17. Apparatus according to claim 16, characterized in that a thread connection apparatus (97) can be brought into the thread path between the pair of draw-off rollers (13) and the auxiliary pair of draw- off rollers (900).

18. Apparatus according to claim 15, characterized in that the auxiliary draw-off apparatus is formed by the bobbin (33) and a drive roll (52) which can be driven in both directions of rotation.

19. Apparatus according to claim 18, characterized in that the drive of the drive roll (52) can be set so as to be adapted to the running-up of the fibre infeed effective in the open-end spinning apparatus.

20. Apparatus according to claim 18 or 19, characterized in that the drive roll (52) bears a casing (53) consisting of a soft material, preferably soft rubber.

21. Apparatus according to one or more of claims 18 to 20, characterized in that a pressing apparatus (7, 70) is associated with the drive roll (52), by means of which pressing apparatus the drive roll (52) is urged with increasing contact pressure against the bobbin (33) as the bobbin diameter increases.

22. Apparatus according to claim 21, characterized in that the drive roll (52) is pressed against the bobbin (33) on the side remote from the bobbin roller (31).

23. Apparatus according to claim 22, characterized in that the drive roll (52) is borne by a pivot arm (50) which is acted upon by a torsion spring (70).

24. Apparatus according to claim 22 or 23, characterized in that the drive roll (52) is borne by a pivot arm (50), the drive of which comprises a rotatable cam disc (62) and an adjustable intermediate lever system (64, 65, 66, 67, 68) between the cam disc (62) and the pivot arm (50).

25. Apparatus according to one or more of claims 14 to 24, characterized by a lifting element (40), which can be inserted between the bobbin roller (31) and the bobbin (33), and a support device (8) adapted to act upon the bobbin arms (32) and, after the lifting element (40) has been withdrawn, ensures a distance (a) which is always the same between the peripheral face of the bobbin (33) and the bobbin roller (31).

26. Apparatus according claim 25, characterized in that the support device (8) comprises a drive lever (80), which can be pivoted by a controllable drive (86), as well as a support lever (81) which is disposed on the drive lever (80) and can be pivoted between two end positions, is acted upon by a resilient element (84) in the direction of the bobbin (33) and can thereby be brought into its first end position (82) and, when running up on one of the two bobbin arms (32), can be brought into its second end position (83), with which a switching apparatus (85) is associated for terminating the pivoting movement of the drive lever (80).

27. Apparatus according claim 26, characterized in that the end positions of the support lever (81) are determined by two stops (82, 83) mounted on the drive lever (80).

28. Apparatus according to claim 26 or 27, characterized in that the controllable drive for the drive lever (80) is constructed as an electric motor (86) and the switching apparatus is constructed as a switch (85) which is disposed on the drive lever (80) and interrupts the current supply to the motor (86) when actuated.

29. Apparatus according to one or more of claims 14 to 28, characterized by a pressure roller which is adapted to be lifted off of the driven draw-off roller and to be put again onto the driven draw-off roller by a servicing apparatus (2) which may be moved along a plurality of open-end spinning devices.

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