EP0084659B1 - Method and device for piecing yarn in an open end spinning unit - Google Patents

Description

The present invention relates to a method for piecing a thread in an open-end spinning device, in which the thread is returned to the open-end spinning device by turning back a bobbin and an auxiliary roller pair and then pulled back from the open-end spinning device while rotating the direction of rotation of the bobbin and after Reaching the normal winding speed is placed in a pair of take-off rollers, and a device for performing this method.

For spinning a thread, it is known to use a device to both lift the bobbin from the main drive roller and keep it separate from it, as well as to deliver the thread back to the spinning device. returned thread is picked up from the bobbin surface with the aid of a suction device and fed to a pair of auxiliary rollers (DE-A 2 008 142, DE-A 2 728 003). The thread on the auxiliary roller pair is brought to a defined length, whereupon a predetermined thread length is delivered to the open-end spinning device by further return delivery. After return delivery, the thread is first drawn off from the open-end spinning device with the aid of the pair of auxiliary rollers until the thread is introduced into the pair of main draw-off rollers after a desired take-off speed has been reached.

With this known method, when piecing, there is only a short period of time between the return of the thread in the spinning rotor and the insertion of the thread withdrawal from the spinning rotor. If this period is exceeded, the thread is turned over so that a thread break occurs. On the other hand, with the short period of time that the thread end can remain in the spinning rotor during the piecing phase, the rotation cannot propagate far into the fiber ring, so that in the case of a very sudden thread take-off, as is the case with the known device, likewise there is a risk of thread breaks.

It is also known to unwind the thread from the spool by hand and return it to the spinning rotor. The bobbin is then brought back into connection with its drive roller, so that the thread is drawn off the bobbin (DE-A 1 560 336) until it is caught by the iridescent thread guide and brought into the area of a catch notch on the pressure roller of the draw-off roller pair which brings the thread into the clamping area of this pair of rollers. In this device, the thread is accelerated abruptly both when the winding begins and when it is caught by the catch notch, which can lead to thread breaks. In addition, it is not possible in the known device to achieve a defined insertion of the trigger, since in the known prior art the coil is supported on the drive device and the different mass of the coil causes a different slip of the coil during the piecing trigger. Tolerances in the shock absorbers and load compensation devices for the bobbin arms also cause different piecing conditions at the different spinning positions of a machine, which makes it difficult to master piecing.

The object of the invention is therefore to provide a method and a device which avoid these disadvantages and ensure a defined insertion of the thread take-off when piecing so that thread breaks on the one hand and undesirable thick spots in the piecing on the other are avoided.

To achieve this object it is provided according to the invention that the thread is released from the auxiliary roller pair after completion of the return delivery and is drawn off only by the bobbin from the open-end spinning device until it is grasped by the take-off roller pair. By releasing the thread by the pair of auxiliary rollers as soon as it has fulfilled its task of returning the thread to the open-end spinning device, the twist in the yarn resulting from the rotation of the spinning rotor in the yarn can be distributed over a relatively large thread length, so that not so much twist gets into the spinning rotor. As a result, more time is available than the dwell time of the thread in the spinning rotor compared to the known method with the aid of a pair of auxiliary rollers during piecing. This longer, available time also enables a softer insertion of the thread take-off. This softer insertion of the thread take-off can be supported by a certain but defined slip of the bobbin. This slip is also advantageous because when spinning, the fiber delivery into the spinning rotor - or another open-end spinning element - does not suddenly occur, but rather increases. The method according to the invention results in a certain approximation of the thread take-off run-up curve to the run-up curve of the fiber feed effective in the spinning rotor. After a short time that is sufficient for the bobbin to reach its full speed, the thread is transferred to the pair of draw-off rollers. Since the thread is already being drawn off the open-end spinning device at full speed at this point, there are no jumps in speed here either, so that the risk of thread breaks during piecing is reduced and the tensile strength in the piecing tool is significantly increased.

The thread take-off is expediently accelerated to the normal speed in a relation which is adapted to the effect of the fiber delivery 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, so that it otherwise leads to a thick point in the thread size ke leading excessive amount of fibers in the open-end spinning station can be avoided, while at the same time due to the increasing rotation propagation in the open-end spinning device, the yarn strength does not drop compared to the previously produced thread piecing.

To carry out the method it is provided according to the invention that the auxiliary roller pair is assigned a control device which, after carrying out the piecing return delivery, releases the clamping of the auxiliary roller pair, while the lifting and driving device has an auxiliary drive roller with a controllable drive which, after the yarn has been returned and after its release is driven by the pair of auxiliary rollers in the opposite direction to pull the thread. As a result, the rotation occurring in the piecing phase can be distributed over a greater length of the thread, so that the risk of overturning the piecing thread end in the spinning rotor is reduced. Furthermore, it is possible to work with significantly higher rotor speeds compared to conventional piecing processes. This means that it is usually not necessary to keep the spinning rotor at a low speed for the piecing process or to monitor its speed, but rather allows piecing at the high production rotor speeds customary today.

The drive of the auxiliary drive roller can expediently be accelerated in a relation which is coordinated with the effect of the fiber delivery in the open-end spinning device, which makes it possible to produce inconspicuous attachments.

To prevent the roller of the auxiliary coil drive from being strongly pressed into the coil, even with a larger coil diameter, it can further be provided according to the invention that the auxiliary drive roller carries a jacket made of a soft material, preferably rubber.

To compensate for the coil mass, which increases more and more with increasing diameter and thus complicates the drive of the coil, it is advantageously provided according to a further development of the subject of the invention that the auxiliary drive roller is assigned a pressing device which the auxiliary drive roller corresponding to the growing coil diameter with increasing contact pressure against the Coil presses. In this way, the increasing inertia of the coil with increasing coil diameter is largely eliminated by increasing the contact forces and thus by reducing the slip. In order to make such a device simple and yet effective, it is advantageously provided that the auxiliary pull-off roller is pressed against the spool by the pressing device from the side facing away from the main drive roller. It is provided that normally an elastic element causes the auxiliary drive roller to bear against the spool.

Since the swivel position of a swivel arm carrying the auxiliary drive roller differs depending on the coil radius, such a device can be developed in such a way that the auxiliary drive roller is carried by a swivel arm on which a torsion spring acts. In this way, the elastic element designed as a torsion spring has a different pretension during the work of the auxiliary drive roller, so that it rests with different force on the coil. By a suitable choice of the characteristics of the elastic element, for. B. by appropriate choice of spring constants, dimensions and bias, can be achieved that a normally different slip with different sizes of coils is avoided, so that regardless of the coil diameter essentially always the same slip and thus always the same piecing conditions can be achieved.

In order to enable adjustment of the swivel arm in a particularly simple manner, it is provided according to a further feature of the invention that the auxiliary 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.

It is advantageous if, depending on the size of the coil, different pivot positions of the swivel arm are obtained, these positions being intended to allow conclusions to be drawn about the coil diameter. In this way, the bias of the torsion spring associated with the pivot lever is precisely matched to the coil size, so that the contact pressure is also adapted to the coil size. In order to achieve this goal in a simple manner, a lifting element with the strength (a), which can be inserted between the main drive roller and the spool, and a supporting device acting on the spool arms are advantageously provided, which after retracting the lifting element always have the same distance which the Thickness (a) of the lifting element corresponds between the circumferential surface of the coil and the main drive roller, even if the lifting element releases the coil again.

In an open-end spinning machine with a large number of open-end spinning devices, it is particularly advantageous if the lifting element is arranged stationary per spinning station, but the support device and the auxiliary drive roller are arranged on a maintenance device which can be moved along the open-end spinning devices. In this way, a less complex winding device suitable for the piecing according to the invention can be created.

In order to avoid contactless monitoring devices for the position of the support device for the coil, since they are susceptible to malfunctions as a result of possibly occurring flight, it is preferably provided that the support device ver by a controllable drive has a pivotable drive lever and a support lever arranged on it and pivotable between two end positions, which is acted upon by an elastic element in the direction of the coil and can thus be brought into its first end position and when it hits one of the two coil arms into its second end position, which is a switching device for Termination of the pivoting movement of the drive lever is assigned. The switching device is actuated mechanically in this way. 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 defined distance between the circumferential surface of the coil and the main drive roller is ensured, so that the lifting element is withdrawn and the support function of the Support device can leave. According to a preferred embodiment of the subject of the invention, the end positions of the support lever are determined by two stops attached to the drive lever. It has also proven to be advantageous to design the controllable drive for the drive lever as an electric motor and the switching device as a switch arranged on the drive lever, which interrupts the power supply to the motor when actuated by the support lever.

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 an exemplary embodiment illustrated in the drawings. Show it :

• 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. In practice, these parts are generally distributed over 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 a few spinning positions.

The spinning machine 1 shown has a large number of spinning stations, of which FIG. 1 only shows one spinning station. 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 the incorporation of fibers in the usual manner with the aid of a fiber delivery device and a dissolving device, for. B. in the form of an opening roller - the fibers fed to the spinning element with the aid of the draw-off roller pair 13 through a draw-off tube 12 from the housing 10. 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 main drive roller 31 and the bobbin 33 by a certain value a from the main drive roller 31 so that one by the strength of the lifting element 4 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 role 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 on 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 feed into the spinning rotor 11 and a lifting of the bobbin 33 from the main drive roller 31 via the thread monitor 36 in that the lifting element 40 forming the essential component of the bobbin lifting device 4 between the bobbin 33 and the 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 independent of the coil diameter is essentially always the same. 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 thread length 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 about the axis 22 from a rest position, 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 pair of auxiliary rollers 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 by the pair of auxiliary rollers 21. The auxiliary roller pair 21 now returns to its rest position. After the thread 3 has been released by the pair of auxiliary rollers 21, the roller 52 is driven in the opposite direction, so that the thread 3 is pulled out of 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 emptied clothing of the opening roller has to be filled again until the full fiber flow can get into the spinning rotor 11, there is a soft effect of the fiber delivery with regard to the spinning rotor 11. In accordance with this effect of the fiber delivery, the thread draw should also be “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 procedure described. is not limited to the 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 device 25. When the thread 3 is subsequently fed to the draw-off tube 12 and fed to the draw-off tube 12 after being cut to a predetermined size, the thread 3 takes one 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 as position B in FIG. 1. In this position B, 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 B ₁ 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 from the ready position B reaches 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 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 that regardless of this diameter, the same path of piecing return delivery achieved by the ejection device 25 can always be provided, the timing relay is set to a longer time adapted to the larger rotor diameter, 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. That can e.g. B. take place so that the take-off roller pair 13 or their driven roller is pivoted away from the thread path during piecing. If the thread clamping is released by lifting the pressure roller from the driven roller of the pair of draw-off rollers 13, the rotation in the direction of the spool can propagate almost unhindered, while the rotation propagation into the spinning rotor 11 through the deflection edge at the mouth of the draw-off tube 12 facing the spinning rotor 11 is difficult.

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 the pulling of 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 when 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 modification is 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 element 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. When a sufficient length of thread has been sucked into the suction tube 20, so that it is ensured that the thread 3 is held securely by the suction tube 20, the thread 3 is inserted into the clamping line of the auxiliary take-off roller pair 900 located near the thread path by conventional means, not shown. The thread still unwound by turning back the bobbin 33 is now picked 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 take-off 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 draw roller pair 900, the thread 3 is again from the spinning rotor 11 deducted. 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 to achieve defined slip ratios when piecing take-off by the coil 33, it is necessary that separate devices are provided for lifting the coil 33 off the main drive roller 31 and for driving the coil. In principle, it is possible that the coil lifting device 4 engages the coil arm 32 or an arm 35 attached to it and at the same time forms the support device 8, i. H. holds the bobbin 33 with its imaginary axis in a particular lifting position during the entire thread break repair. 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 also be arranged either on the drive lever 80 or on the support lever 81 or on both Lever be divided.

The support device 8 does not have to be supported on an additional arm 35 of the coil arm 32. but can also attack it itself or an extension of it.

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 pipe 21 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 (14)

1. Method for joining a thread in an open-end spinning apparatus, in which the thread is delivered back to the open-end-spinning-apparatus by winding back a bobbin and an auxiliary pair of rollers and subsequently is again drawn out of the open-end spinning apparatus by changing the rotational direction of the bobbin and is introduced into a pair of draw-off rollers after the normal winding speed has been reached, characterized in that, after termination of the return- delivery, the thread is released from the auxiliary pair of rollers and, until the seizure by the pair of draw-off rollers is drawn-off from the open-end spinning apparatus exclusively by means of the bobbin.

2. Method according to claim 1, characterized, in that the thread draw-off is accelerated up to the normal speed in a relation adapted to the becoming effective of the fiber infeed with respect to the open-end spinning apparatus.

3. Apparatus for performing the method according to claim 1 or 2, with a winding apparatus having a drive roller for driving of a bobbin, with a lifting and driving device for lifting the bobbin off from the main drive roller and for driving the bobbin when being lifted off from the main driving roller, with an auxiliary pair of rollers for delivering the thread back into the open-end spinning device as well with a pair of draw-off rollers for withdrawing the thread out of the open-end spinning device, characterized in that to the auxiliary pair of rollers (21) is associated a control device (9) which after having performed the backdelivery releases the clamping action of the auxiliary pair of rollers (21), and that the lifting and the drive device has an auxiliary drive roller (52) with an adjustable drive which, after the return delivery of the thread (3) and its release by the auxiliary pair of rollers (21) is driven in the opposite direction in order to withdraw the thread (3).

4. Apparatus according to claim 3, characterized in that the drive of the auxiliary drive roller (52) is adapted to be accelerated in a relation which is adapted to the becoming effective of the fiber infeed with respect to the open-end spinning apparatus.

5. Apparatus according to claim 3 or 4, characterized in that the auxiliary drive roller (52) bears a cover (53) consisting of soft material, preferably soft rubber.

6. Apparatus according to one or more of claims 3 to 5, characterized in that to the auxiliary drive roller (52) is associated a loading device (7, 70) which presses the auxiliary drive roller (52) with an increasing loading pressure against the bobbin (33) corresponding to the increasing diameter of the bobbin.

-7. Apparatus according to claim 6, characterized in that the auxiliary drive roller (52) is pressed against the bobbin (33) by means of the loading device (7, 70) on the side facing away from the main drive roller (31).

8. Apparatus according to claim 7, characterized in that the auxiliary drive roller (52) is supported by a pivot arm (50) upon which a torsion spring (70) acts.

9. Apparatus according to claim 7 or 8, characterized in that the auxiliary drive roller (52) is supported by a pivot arm (50), the drive of which has a rotatable cam disc (62) as well as an adjustable intermediate lever system (64, 65. 66, 67, 68) between the cam disc (62) and the pivot arm (50).

10. Apparatus according to one or more of claims 3 or 9, characterized by a lifting element (40) having a thickness (a) and being adapted for being slid between the main drive roller (31) and the bobbin (33), and by a supporting device (8) for acting upon the bobbin arms (32) which supporting device, after retraction of the lifting element (40). ensures the constant equal distance which corresponds to the thickness (a) of the lifting element (40), between the peripheral surfaces of the bobbin (33) and the main drive roller (31).

11. Apparatus according to claim 10, characterized in that, in the case of an open-end spinning machine (1) with a plurality of open-end spinning devices, the lifting element (40) is disposed so as to be stationary for each spinning station and the supporting device (8) as well as the auxiliary drive roller (52) are disposed on a servicing device (2) which may be moved along the open-end spinning devices.

12. Apparatus according to claim 10 or 11, characterized in that the supporting device (8) comprises a drive lever (80) which may be pivoted by controllable drive (86), as well as a supporting lever (81) which is arranged on the drive lever and may be pivoted between two end positions, which supporting lever is acted upon by a resilient element (84) in the direction towards the bobbin (33) and thereby may be brought into its first end position (82) and, by running up on one of the two bobbin arms (32) may be brought into its second end position (83), with which a switching apparatus (85) for terminating the pivotable movement of the drive lever (80) is associated.

13. Apparatus according to claim 12, characterized in that the end positions of the supporting lever (81) are determined by two stops (82, 83) mounted on the drive lever (80).

14. Apparatus according to claim 12 or 13, characterized in that the controllable drive (86) for the drive lever (80) is constructed as an electric motor (86) and the switching device (85) is constructed as a switch which is arranged on the drive lever (80) and interrupts the supply of current to the motor (86) when actuated.

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