EP2172409B1 - Method for emptying a pneumatic thread storage device - Google Patents

Description

The present invention relates to a method for emptying a pneumatic thread storage device on a textile machine producing cross-wound bobbins after a thread break according to the preamble of claim 1 and to an apparatus for carrying out the method according to the preamble of claim 11.

From the DE 10 2007 038 871 A1 a method for piecing on open-end spinning machines is known in which after piecing the spun yarn is withdrawn from the spin agent and wound on a package reel. To carry out the piecing process, the thread which comes from the package, for example stored in the form of a loop in a pneumatic thread store, which is then emptied during the winding process. For emptying the yarn store, the package is subjected to acceleration during a start-up phase, which is controlled such that the take-up speed is first increased in a plurality of change steps and then reduced. The winding speed is increasingly increased. The thread withdrawal device is started or accelerated at the same time or leading to the package. During the step-by-step acceleration of the winding speed, it becomes larger than the thread pulling speed at a time. While prior to this time, the thread take-off speed was greater than the take-up speed and an overdelivery, there is an under-delivery after this time, since the thread take-off speed is less than the take-up speed. In this way, emptying of the thread storage is achieved. During the transition from the start - up phase into the operating phase, the Speed difference between the winding speed and the thread withdrawal speed zero.

A disadvantage of the method according to the prior art proves that in particular those packages, which are wound to more than two-thirds, are heavily slippery due to their inertia during startup. This has the consequence that the emptying of the thread storage, which must be completed with the transition from the start-up phase into the operating phase, is not exactly reproducible. In order to achieve reproducibility, according to the DE 10 2007 038 871 A1 the thread store is equipped with at least one sensor device connected to a control device, which is designed such that it generates a signal when the fill level of the thread store falls below a defined size. By means of a second arranged in the thread storage sensor device which is also connected to the control device, a further signal is generated when the yarn store is completely emptied. The respective level signals are used in the control of the piecing process for controlling the winding speed. However, the use of sensor devices can not solve the problem resulting from the response times of commercially available sensor devices. Due to the reaction time, the sensor device closest to the outlet opening is placed at a distance therefrom as a function of the maximum withdrawal speed in order to ensure that the last thread section leaving the thread store is reliably detected within the reaction time. With different coil diameters, however, the distance between the sensor device and the outlet opening is too large, so that the remaining thread length must be mathematically derived from the current withdrawal and winding speed, which with corresponding inaccuracies, For example, due to the slip occurring between the winding shaft and the cross-wound bobbin, or the reaction inertia of the control device in the respective operating state, goes hand in hand.

Furthermore, a method for emptying the thread memory from the DE 196 36 395A1 Known in which prior to piecing after a yarn breakage initially a defined length of thread is unwound from the package and cached in the thread storage device. Subsequently, depending on the startup behavior of the spinning rotor, the winding shaft is started at a first point in time relative to the thread withdrawal device and accelerated constantly. The faster-rising thread withdrawal device is started at a second time, which corresponds approximately to reaching 70% of the production speed of the spinning rotor. At a third time, the peripheral speeds of the winding shaft and the thread take-off device are equal and are then accelerated synchronously up to their production speed, wherein the run-up of the spinning rotor is the reference variable of the acceleration.

Also in this method, it proves to be disadvantageous that as a result of the slip occurring at the driven coil determination of the withdrawn at the initial acceleration of the thread storage device thread length only by the use of sensors in the yarn storage device with the disadvantages already described above is possible.

Based on the aforementioned prior art, the present invention seeks to provide a method for emptying a yarn storage device on a textile machine producing cross-wound bobbins, which allows a reliable detection of the thread length contained in the thread store, without using a sensor. In addition lies The invention has for its object to provide an apparatus for performing the method.

The object is achieved with regard to the method by the characterizing features of claim 1 and with respect to the device by the characterizing features of claim 11.

Advantageous developments of the invention are described in the respective subclaims.

According to claim 1 is proposed to solve the problem that the winding shaft and the Fadenchangiereinrichtung be accelerated at a first time in each case to a constant base speed, which is below 30% of the operating speed in the stationary spinning process. As a result of this first method step, the slip occurring in the reel start-up is markedly reduced since, in order to overcome the breakaway torque of the winding shaft, it is initially operated at a constant, low speed at the start of the run-up. The acceleration of the Fadenchangiereinrichtung to a constant base speed allows an accurate and reproducible determination of the wound up during this first section of the emptying thread length. The base speed of the winding shaft and the Fadenchangiereinrichtung vary depending on the respective bobbin diameter and the winding speed in the stationary spinning operation. The laying width of the Fadenchangiereinrichtung takes place from the first time within a reduced by at least 50% compared to the nominal stroke laying width to the coil center and is extended in a second time almost to the nominal stroke. This serves to avoid uncontrolled laying of the thread on the spool. In the second time the Thread extractor started and accelerated. In addition, starting from the second point in time, the winding shaft and the thread-changing device are accelerated to their final speed in stationary spinning operation up to a third point in time, starting from their respective base speed and the thread withdrawal device. Due to the temporal advance of the start of the winding shaft is achieved that complete the winding shaft and the thread take-off their ramp-up together with the achievement of the speed of the spinning rotor of the spinning device for the stationary spinning process. During the overfeed of the winding shaft, the required thread length is removed from the yarn store. The required stored thread length is calculated from the required thread length for the supply of the winding shaft relative to the thread withdrawal device. Especially with large bobbin diameters and high bobbin withdrawal speeds, the yarn store must be filled to a maximum in order to simultaneously end the run-up of the winding shaft drive with the run-up of the thread take-off drive.

In this case, the duration of the acceleration phase should be calculated from the second point in time as a function of the thread length located in the thread storage device. This serves to coordinate the acceleration behavior of the winding shaft, the thread withdrawal device and the thread-changing device during the emptying of the thread storage device.

For this purpose, the winding speed during startup can be detected to calculate the thread length located in the thread storage device. For this purpose, the use of a suitable sensor is required, which has a high resolution, for example, the arrangement of a plurality of magnets in the sleeve plate, whereby a sufficient number of pulses for accurate detection of the winding speed even during startup of the coil is achieved.

Alternatively, for calculating the thread length located in the thread storage device, the thread laying can be carried out with a reduced laying width, within which the thread is deposited almost parallel on the cross-wound bobbin. The parallel laying down of the thread allows a simple and accurate determination of the thread length applied to the bobbin in order to be able to deduce the thread remaining length in the thread storage device. If the emptying of the yarn storage device is completed at the third time, the laying width is increased to the nominal stroke, which is the basis of the stationary spinning operation. This variant is less expensive than the use of a sensor and requires no installation space on the winding device.

Preferably, the reduced speed of the thread take-off device can be set by means of a correction value which varies as a function of the respective package diameter. As a result, the emptying of the thread storage device can be controlled specifically. In order to avoid unevenness of the yarn count during the process of emptying, the correction value for the duration of the emptying is transmitted in the same way to the drive of the sliver feeder.

In this case, the speed of the thread withdrawal device can be changed stepwise until complete emptying of the thread storage.

The gradual change in the speed of the thread take-off device can be achieved by a variation of the correction factor.

In particular, a division of the process of emptying the yarn storage device into several phases may be provided, in which the correction factor is varied.

Advantageously, a higher rotation coefficient is set by the variation of the correction factor during the emptying of the thread store. As a result, a compensation of the increase in the yarn diameter is achieved during the rotor ramp-up phase, which occurs in particular at low rotor speeds due to the reduced centrifugal forces. The yarn produced during the emptying thus has a yarn diameter which at least approaches or equals the diameter of the yarn produced during the stationary spinning operation.

In this case, the rotation coefficient can be changed gradually until the complete emptying of the thread storage.

Furthermore, the invention relates to a cheese-producing textile machine with a plurality of similar jobs for performing the method, which is characterized in that each workstation has a control device which is adapted to the drives of the winding shaft and the Fadenchangiereinrichtung at a first time in each case to a accelerate constant pedestal speed, which is below 30% of the operating speed, and then at a second time to start the thread withdrawal device, and that the control device is adapted, starting from the second time, the winding shaft and the Fadenchangiereinrichtung from its base speed and the thread withdrawal device on to accelerate their final speed in stationary spinning operation.

The control device can be set up to determine the thread residual length in the thread storage device in such a way that it can reduce the nominal stroke of the thread switching devices for the duration of the emptying of the thread storage device.

In this case, the control device may be configured to control the laying width of the Fadenchangiereinrichtung such that the laying takes place from the first time within a reduced laying width to the coil center, and is extended in the second time almost to the nominal stroke.

Alternatively, the control device for determining the thread residual length in the thread storage device may be connected to encoders which detect the rotation of the cross-wound bobbin.

The present invention will be explained in more detail with reference to embodiments shown in the drawings.

Fig. 1

in perspektivischer Darstellung eine Arbeitsstelle einer Offenend-Rotorspinnmaschine;

Fig. 2

schematisch in Seitenansicht eine Offenend-Rotorspinnmaschine mit einem Wartungsaggregat;

Fig. 3

den Bereich der Spinnstelle sowie einen Teil des Wartungsaggregates gemäß Fig. 2;

Fig. 4

ein Geschwindigkeits-Zeit-Diagramm zur Veranschaulichung des Vorganges der Leerung der Fadenspeichereinrichtung.

Show it:

Fig. 1

in perspective view of a job of an open-end rotor spinning machine;

Fig. 2

schematically in side view an open-end rotor spinning machine with a maintenance unit;

Fig. 3

the area of the spinning station and a part of the maintenance unit according to Fig. 2 ;

Fig. 4

a speed-time diagram for illustrating the process of emptying the thread storage device.

Fig. 1 shows a perspective view of a workstation of an open-end rotor spinning machine, which, as known and therefore shown only schematically, has an open-end spinning device 2 for producing a thread 9 and a downstream in the thread running direction F winding device 3. On this winding device 3, the thread 9 is wound into a package 8. The open-end spinning device 2 comprises a spinning rotor, not shown, which is driven by a single motor.

The thread 9 produced in the open-end spinning device 2 is, as indicated, withdrawn from the open-end spinning device 2 by a thread take-off device 13, which has a thread take-off roll 10 which can be driven by a single motor and a rollable roller 14 which can be pulled by the thread take-off roll 10.

As in Fig. 1 further indicated, leaves the thread 9, the open-end spinning device 2 by a so-called thread withdrawal tube 17, in the area also a pivotally mounted Anspinnhilfsorgan 16 is arranged, which takes after a thread interruption by a suction nozzle 4 from the cheese 8 retrieved thread 9 and the Thread end prepared for thread connection.

Furthermore, a thread monitor 15, a mechanical thread storage device 7, a pneumatic thread storage device 12 and a waxing device 5 are arranged in the area of the thread running path. The pneumatic thread storage device 12 is designed as a discontinuous working memory, that is, the thread storage device 12 is completely emptied after each thread connecting operation. During operation of the open-end spinning device 2 is the Thread storage device 12 is acted upon by a vacuum source, not shown, with suction air.

The winding device 3 consists, as usual, from a creel 22 for rotatably holding a cross-wound bobbin 8, a preferably via a reversible single drive 19 driven winding shaft 23 and a single motor driven Fadenchangiereinrichtung 24, which is driven for example via a stepper motor.

Furthermore, such work stations 1, as already mentioned, have a suction nozzle 4, which is adjustable by means of a motor 6 between a thread receiving position lying in the region of the winding device 3 and a yarn transfer position lying in the region of the spinning device 2.

As usual, the individual stepper motors of the components of the workstation 1 via various control lines to a control device, in the present embodiment, to a workstation computer 18, connected. As a result, the individual motor drives of the components of the workstations 1 are independently controllable. Alternatively, the control device can be designed as a central computer of the open-end rotor spinning machine.

In Fig. 2 is a spinning machine 31 shown, on which a guide rails 43, 44 and a support rail 45 movable maintenance unit 46 is arranged. The drive 47 of this maintenance unit 46 has rollers 48 and a support wheel 49. The supply of the piecing carriage 46 with electrical energy is preferably carried out, as indicated, via a sliding contact device 50.

Such maintenance units 46 have numerous bobbin and thread handling devices, such as a winding drive 40 and a thread take-off device 51 and patrolling constantly along the open-end rotor spinning machine 31. The maintenance unit 46 intervenes automatically when a need for action arises at one of the workstations 32. Such a need for action exists, for example, if a yarn break has occurred at a workstation 32 or if a cross-wound bobbin 38 has reached its prescribed diameter at one of the workstations 32 and has to be exchanged for an empty tube.

In the event of a yarn breakage, the maintenance unit 46 runs to the relevant workstation 32, positioned there and looks at a "normal" yarn breakage with his (not shown) Fadensuchdüse the torn, lying on the peripheral surface of the package 38 thread end. After cleaning the spinning unit, this thread end, as usual, by known handling devices, after appropriate preparation, in the area of the spinning unit 33, transported there in the thread withdrawal tube and kept ready for the actual piecing process. At the same time, a defined thread length is unwound and temporarily stored in a thread store 52 via the winding drive 40 from the package 38.

As in Fig. 3 Shown on a larger scale, both the winding drive 40 and the thread take-off device 51 each have their own, on the maintenance unit's own control device 53 selectively controllable drive 54 or 55 on. The drive 54 acts on the drive roller 56 of the winding drive 40, while the drive 55 on the take-off roller 57 of Thread withdrawal device 51 of the maintenance unit 46 is connected. The thread take-off device 51 also has, as usual, a pressure roller 58. Between the thread take-off device 51 and the winding drive 40, a pneumatic yarn store 52 is arranged, in which a thread 37 is cached in a loop shape. The yarn store 52 is formed as a discontinuous working memory, that is, it is emptied at each piecing. The yarn store 52, which operates on the "last-in-first-out" principle, can be acted upon with suction air via a vacuum source 59.

The inventive method is described below with reference to in Fig. 1 illustrated embodiment of the open-end rotor spinning machine and the in Fig. 4 Described velocity-time diagram describe.

When a thread interruption occurs, the drives of the thread take-off roll 10, the thread-changing device 24 and the winding shaft 23 are first set to a standstill and the cross-wound bobbin 8 to be produced is lifted off the winding shaft 23 by means of the creel 22. Subsequently, a piecing process is initiated, wherein the drives of the spinning rotor, the thread take-off roll 10, the thread-changing device 24 and the winding shaft 23 are taken to initiate the yarn joining operation again in operation. The commissioning of the thread take-off roll 10, the Fadenchangiereinrichtung 24 and the winding shaft 23 is carried out taking into account temporally coordinated acceleration processes of the individual drives, which are based on the run-up behavior of the drive of the spinning rotor.

Due to the different mass moments of inertia of the individual components to be driven, there is a difference in the acceleration behavior of the yarn take-off roll 10 and the winding shaft 23, which can reach a ratio of 1:10 or higher depending on the respective spinning conditions. Since the moment of inertia of the winding shaft 23 increases with increasing diameter of the cheese 8, while the moment of inertia of the thread take-off roll 10 always remains constant and also the drive slip is to be considered in the winding shaft 23, the thread take-off roll 10 always before the winding shaft 23 their operating speed in normal spinning operation to reach.

Accordingly, for the period from the start of the winding shaft 23 to reach the operating speed in the normal spinning operation, the excess length of the thread 9 produced by the open-end spinning device 2, which can not be wound by the cheese 8 due to the slow speed of the winding shaft 23, be temporarily stored, which is realized via the thread storage device 12. The problem occurring here is the reduced winding tension, which is present during the emptying of the thread storage device 12 after the yarn joining operation, since the winding tension of the thread 9 is generated during this period only by the upcoming in the thread storage device 12 negative pressure. The reduced winding tension leads during this period to a winding of loose thread layers on the cheese 8.

This requires the monitoring and detection of the reliable withdrawal of the thread 9 from the yarn storage device 12, that is, the complete emptying of the yarn storage device 12 should be as fast as possible to loosely wound To avoid yarn layers due to reduced winding tension, as well as an overflow in the yarn storage device 12 due to a too small speed difference between the thread take-off device 13 and the winding shaft 23. The monitoring and detection of the emptying of the yarn storage device 12 should be as accurate as possible to spikes, the Platzer may have to be avoided. In addition, the storage content of the yarn storage device 12 should be as low as possible in order to avoid a curl when the yarn is spinning up.

The use of sensors in the yarn storage device 12 has proved to be too imprecise because factors such as the occurring slip of cheeses 8 with a diameter greater than 300 mm during startup of the winding shaft 23, the time of detection of the thread 9 by the Fadenchangiereinrichtung 24 after the start of the winding shaft 23 and the thread length laid in this time, but also the reaction times of a sensor at high take-off speeds of 250 m / min and more, have a strong influence on the accuracy of determining the withdrawn from the yarn storage device 12 thread length. Thus, the invention proposes a method for operating the cheese-producing textile machine, which allows reliable emptying of the thread storage device 12 without the use of additional sensors in the thread storage device 12.

According to the invention, after the start of the drive of the spinning rotor, the winding shaft 23 is accelerated at a first point in time t1 with respect to the thread withdrawal device 13 in advance to a base speed SG_WW, which is below the end speed of the winding shaft 23 in the spinning process. The individual drive 19 of the winding shaft 23 is accelerated to the constant base speed SG_WW to the breakaway torque to overcome the single drive 19, as in Fig. 4 is shown. As a result, a significant reduction of the slip during the coil run-up is achieved. The base speed SG_WW is a function of the respective coil diameter and the winding speed in stationary spinning operation and is below 30% of the operating speed.

Simultaneously with the starting of the individual drive 19 of the winding shaft 23, the thread-changing device 24 is put into operation and also accelerated to a base speed SG_FF, as in Fig. 4 is shown. The speed of the Fadenchangiereinrichtung 24 is kept constant until the start of the thread withdrawal device 13 at a second time t2. In order to allow an accurate calculation of the withdrawn from the thread storage device 12 thread 9 at this time, the thread 9 is deposited in approximately parallel layers on the cheese 8. For this purpose, the traverse stroke takes place within a reduced range around the middle of the cross-wound bobbin 8. The reduced traversing width can be, for example, up to 50 mm during this phase. The almost parallel laying of the thread 9 while avoiding a punctiform deposit on the cheese 8 allows a very accurate calculation of withdrawn from the yarn storage device 12 since the start of the winding shaft 23 thread length.

Delayed in time to the start of the winding shaft 23 and the Fadenchangiereinrichtung 24, the thread take-off device 13 is started and accelerated at the second time t2. The higher dynamics of the drive of the thread withdrawal device 13 allows the simultaneous completion of the run-up of winding shaft 23 and thread take-off device 13 together with the achievement of the rotational speed of the spinning rotor of the spinning device 2 for the stationary spinning process. By starting the Thread withdrawal device 13, the stroke width of the thread-changing device 24 is increased, so that sets almost the laying width in the stationary spinning operation on the cross-wound bobbin 8. As a result, for the duration of emptying the yarn storage device 12, the risk of tees at the edge of the cross-wound bobbin 8 due to a lower winding tension is counteracted.

In the second time t2, the winding shaft 23 and the Fadenchangiereinrichtung 24 are accelerated from their respective base speed SG_WW or SG_FF to their final speed, which have the winding shaft 23 and the Fadenchangiereinrichtung 24 in the stationary operation of the spinning process, wherein the thread take-off device 13 and the winding shaft 23 for the duration of the emptying of the yarn store 12 are driven at a speed which lies below their intended final spinning speed in the stationary spinning process.

With the attainment of the final speeds of the winding shaft 23, thread take-off device 13 and spinning rotor, the laying width of the thread switching device 24 is increased according to the actual width of the cross-wound bobbin 8 in the stationary spinning operation at a third time t3. The final speed of the winding shaft 23 is calculated as follows: $${\mathrm{v}}_{\mathrm{WW}}\mathrm{=}\frac{{\mathrm{n}}_{\mathrm{rotor}}}{\mathrm{T}\mathrm{/}\mathrm{m}}\mathrm{*}{\mathrm{tension\; draft}}_{\mathrm{spinning\; operation}}\mathrm{,}$$

In order to refine the determination of the thread length withdrawn from the thread storage device 12, the process of emptying the thread storage device 12 can be subdivided into several phases from the second point in time t2. This is done according to the number of individual phases Correction factor Factor _memory clears that affects the speed of the thread take-off device 13. The mathematical relationship is shown below: $${\mathrm{v}}_{\mathrm{deduction}}\mathrm{=}\frac{{\mathrm{n}}_{\mathrm{rotor}}}{\mathrm{T}\mathrm{/}\mathrm{m}}\mathrm{*}{\mathrm{factor}}_{\mathrm{Empty\; memory}}$$

In the above formula, n _rotor describe the speed of the spinning rotor, T is the twist per meter in the spun yarn as well as the correction factor factor _{memory emptying} the percentage reduction of the draw-off speed during the emptying of the thread storage device 12. For the correction factor factor _{memory emptying} are thereby different from each other in the individual phases Values are selected, whereby the value of the correction factor factor _memory vacancies increases from phase to phase. The factor _memory deficit factor is also applied to the drive of the sliver draw to avoid irregularities in the yarn count during the process of emptying the yarn store 12. As a result, a change in the rotation coefficient α is achieved, which is effective for the duration of the emptying of the yarn storage device 12. The change of the rotation coefficient α causes a compensation of the occurring diameter deviation of the thread 9 during the run-up of the spinning rotor to its operating speed.

Starting from a value of the correction factor factor _memory vacancies between 0.8 and 0.9 in the first phase of emptying, the value of the correction factor factor _memory vacancy is increased, for example, to 0.92 to 0.98, depending on the thread length remaining in the thread store 12. In the last phase immediately before the emptying of the thread memory 12, a value between 0.99 and 0.9999 is set. The value of the Correction Factor _Memory Accumulation factor should be selected so that the winding tension within the last phase is normal the winding tension of the stationary spinning operation assumes. Only with the attainment of the normal value of the winding tension, the laying should be made over the entire stroke width, since thus the risk of tees on the flanks of the cheese 8 is minimized.

The third time t3 characterizes the achievement of the stationary spinning operation, ie the time at which the emptying of the yarn store 12 is completed, as well as the drives of the thread take-off device 13 as well as the sliver feed serving drive are no longer loaded with the correction factor factor _{memory leaks} . At this time, the speed difference between the thread take-off device 13 and the winding shaft 23 corresponds to the tensioning delay. The control and monitoring of the process takes place by the control device 18 of the respective spinning station. 1

The procedure is likewise at the in Fig. 2 described open-end rotor spinning machine with a maintenance unit 46 feasible, since the drives for both the winding drive 40 and the thread withdrawal device 51 on the maintenance unit 46 by means of the maintenance unit's own control device 53 are controlled separately.

The implementation of the method according to the invention is equally conceivable on winding machines, which also have individual motor driven components and a thread storage device, since at these due to the much higher processing speed, the problem described occurs even more.

Claims (14)

1. Method for emptying a pneumatic thread storage mechanism (12, 52) of a textile machine producing cross-wound bobbins after a thread interruption, at which by means of a maintenance assembly (46), which can be moved or is present in each case at workstations (1, 32), the thread interruption is eliminated by a thread connecting mechanism (2, 33) with which the thread storage mechanism (12, 52) is associated, in which a predetermined thread length is temporarily stored and from which the thread (9, 37) is drawn off by a winding device (3, 34) and is wound onto the cross-wound bobbin (8, 38) driven by a winding shaft (23, 40), on which cross-wound bobbin it is displaced by means of a thread traversing mechanism (24), the thread being drawn off from a spinning device by means of a thread draw-off mechanism (13, 51),
   characterised in that

   - the winding shaft (23, 40) and the thread traversing mechanism (24) are in each case accelerated at a first instant (t1) to a constant base speed (SG_WW, SG_FF), which is below 30% of the operating speed;

   - in that the displacement width of the thread traversing device (24) from the first instant (t1) takes place within a displacement width reduced by at least 50% compared to the nominal traverse, around the bobbin centre, and at a second instant (t2) is extended virtually to the nominal traverse;

   - in that from the second instant (t2) the thread draw-off mechanism (13, 51) is started and accelerated;

   - in that from the second instant (t2), the winding shaft (23, 40) and the thread traversing mechanism (24), proceeding from their base speed (SG_WW, SG_FF) and the thread draw-off mechanism (13, 51), are accelerated to their final speed during stationary spinning operation up to a third instant (t3).
2. Method according to claim 1, characterised in that the duration of the acceleration phase from the second instant (t2) is calculated as a function of the thread length located in the thread storage mechanism (12, 52).
3. Method according to claim 2, characterised in that the winding speed is detected during the run-up to calculate the residual thread length located in the thread storage mechanism (12, 52).
4. Method according to claim 2, characterised in that the thread displacement is carried out up to the second instant (t2) with a reduced displacement width, so the thread (9, 37) is deposited virtually in parallel on the cross-wound bobbin (8, 38) to calculate the thread lengths located in the thread storage mechanism (12, 52).
5. Method according to any one of claims 1 to 4, characterised in that the speed of the thread draw-off mechanism (13, 51) is adjusted by means of a correction value which varies as a function of the respective bobbin diameter.
6. Method according to any one of claims 1 to 5, characterised in that the speed of the thread draw-off mechanism (13, 51) is changed in steps until the thread store (12, 52) has been completely emptied.
7. Method according to claim 6, characterised in that a variation in the correction factor is carried out for the step-wise change of the speed of the thread draw-off mechanism (13, 51).
8. Method according to claim 7, characterised in that a division of the process of emptying the thread storage mechanism (12, 15) into a plurality of phases is provided, in which the correction factor is varied.
9. Method according to any one of claims 5 to 8, characterised in that a higher coefficient of rotation α is adjusted by the variation of the correction factor during the emptying of the thread store (12, 52).
10. Method according to claim 9, characterised in that the coefficient of rotation α is changed in steps up to the complete emptying of the thread store (12, 52).
11. Textile machine (31) producing cross-wound bobbins with a large number of similar workstations (1, 32) for carrying out the method according to any one of claims 1 to 10, which has a moveable maintenance assembly (46) or maintenance assembly present in each case at the workstations (1), with a thread connecting mechanism (2) for eliminating a thread interruption, which is associated with a thread storage mechanism (12, 52), in which a defined thread length is stored after the elimination of the thread interruption, as well as a thread draw-off mechanism (13, 51) connected downstream of the thread connecting device (2) for drawing off the thread (9, 37) from the thread storage mechanism (12, 52), and a winding shaft (23, 40) driving the cross-wound bobbin (8, 38) to wind on the thread (9, 37),
    characterised in that

    - each workstation (1, 32) has a control mechanism (18, 53), which is set up to accelerate, in each case, the drives of the winding shaft (23, 40) and the thread traversing device (24) at a first instant (t1) to a constant base speed (SG_WW, SG_FF), which is below 30% of the operating speed;

    - in that the control mechanism (18, 53) is set up to start the thread draw-off mechanism (13, 51) at a second instant (t2); and

    - in that the control mechanism (18, 53) is set up, from the second instant (t2), to accelerate the winding shaft (23, 40) and the thread traversing mechanism (24), proceeding from their base speed (SG_WW, SG_FF), and the thread draw-off mechanism (13), to their final speed during stationary spinning operation at an instant (t3).
12. Textile machine producing cross-wound bobbins according to claim 11, characterised in that the control mechanism to determine the residual thread length in the thread storage mechanism is set up in such a way that the control mechanism can reduce the nominal traverse of the thread traversing mechanisms for the duration of emptying the thread storage mechanism.
13. Textile machine producing cross-wound bobbins according to claim 12, characterised in that the control mechanism (18, 53) is set up to control the displacement width of the thread traversing mechanism (24) in such a way that the displacement takes place from the first instant (t1) within a reduced displacement width around the centre of the cross-wound bobbin (8, 38), and is extended, at the second instant (t2), virtually to the nominal traverse.
14. Textile machine producing cross-wound bobbins according to claim 12, characterised in that the control device (18, 53), to determine the residual thread length in the thread storage mechanism, is connected to pulse transmitters, which detect the rotation of the cross-wound bobbin (8, 38).

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