EP2985251A1 - Method and device for avoiding pattern windings during the winding of a cross-wound bobbin - Google Patents

Abstract

The present invention relates to a method of avoiding image windings when winding a cross-wound bobbin (8) driven by a drive drum (2) provided with reverse thread grooves (2 '') for the thread guide, the drive drum (2) having acceleration phases (BP) , which are each followed immediately by a deceleration phase (AP), characterized in that - That the drive drum (2) during the acceleration (BP) and Abbremsphasen (AP) has a higher peripheral speed than the cheese (8), - That the Abbremsphasen (AP) are terminated at the time in which the peripheral speed of the drive drum (2) has fallen to that of the cheese (8), - And that the braking phases (AP) are each followed by a synchronization phase (GP), in which the peripheral speeds of the drive drum (2) and cheese (8) are the same. However, the invention also relates to a device for carrying out this method.

Description

The invention relates to a method for avoiding image windings during winding of a cross-wound bobbin and to an apparatus for carrying out such a method.

Cross-wound bobbins are produced by corresponding textile machines, which typically consist of a multiplicity of similar work stations, each producing a cross-wound bobbin, which are provided by means which are central to the textile machine, such as e.g. be supplied with a power supply. Such a textile machine may, in particular, be an automatic winder which wraps a plurality of relatively small-volume spinning cops into a cross-wound bobbin having a substantially more yarn material, or else a spinning machine.

In a cross-wound bobbin, the thread is wound obliquely to the longitudinal axis of the cross-wound bobbin. The thread initially moves, e.g. with an inclination to the right from the left end face of the cheese to its right, then after reaching the right front side to change the inclination to the left and be moved back to the left end, whereby a so-called double stroke is terminated and by changing the inclination Crossing angle of the thread on the cheese is formed.

In addition to the use of a left to right and back oscillating traversing yarn guide to achieve the traversing movement, the use of a grooved drum with Kehrgewinderillen thread guide a cost-effective and therefore often used option. Typically, such a grooved drum is used simultaneously to drive the cross-wound bobbin. For this purpose, the then also drum drive groove drum is in frictional engagement with the cheese and the peripheral speeds of the drive drum and cheese are the same except for certain differences caused by slippage.

Since, in this situation, the rotations of the drive drum and cross-wound bobbin are coupled to each other periodic processes, it comes with certain diameters of the cheese to form so-called images or mirrors, ie, after completion of a double stroke, the thread is relocated at the same location or in the immediate vicinity, where he was already relocated on an earlier double stroke.

This situation occurs e.g. whenever a double stroke completes one or more complete reels.

The threads are then at such locations then, directly or separately by thread interleaves, one above the other or closely to each other and thereby produce at these points a) a higher package density and b) an unstable stratification. The former has disadvantages in dyeing the bobbin, since such densified areas are impregnated weaker than the other sites and thus only unevenly colored. The latter has disadvantages with respect to the coil stability and the run-off properties during subsequent unwinding of the cross-wound bobbin, since the layered layers of thread can slip off and become jammed together.

This problem of image formation has been known for a long time, and many methods of so-called image disturbance, that is, avoidance of the aforementioned harmful periodic relationships, have been developed by varying the relative peripheral speeds of the drive drum and cross-wound bobbin. This can be done e.g. Alternately accelerating, decelerating or free running the drive drum itself may temporarily slow down the cheese or may vary the frictional engagement between the drive drum and cross-wound bobbin by a limited lifting of the cheese from the drive drum, and one can also combine all of these possibilities. The challenge is to achieve sufficient image disturbance with minimal additional energy input and maintaining high productivity.

The EP 0 399 243 B1 On the one hand gives an overview of known methods and proposes on the other hand, a separate process in which the drive drum is periodically alternately accelerated and decelerated so that the peripheral speed of the cheese follows that of the drive drum, eg with a fixed phase shift. As a result, the difference between the peripheral speeds of the drive drum and the cheese constantly changes, resulting in an effective image disturbance.

Against this background, it is therefore an object of the present invention, the known methods for image disturbance and in particular the method discussed above of the EP 0 399 243 B1 to further develop it so that at least one of the objectives image quality, productivity and energy use are improved:

• dass die Antriebstrommel während der Beschleunigungs- und Abbremsphasen eine höhere Umfangsgeschwindigkeit aufweist als die Kreuzspule,
• dass die Abbremsphasen in dem Zeitpunkt beendet werden, in dem die Umfangsgeschwindigkeit der Antriebstrommel auf die der Kreuzspule gesunken ist,
• und dass die Abbremsphasen jeweils von einer Gleichlaufphase gefolgt werden, in der die Umfangsgeschwindigkeiten von Antriebstrommel und Kreuzspule gleich sind.

The object is achieved by a method for avoiding image windings during winding of a cross-wound bobbin, which is driven by a drive drum provided with reverse thread grooves for the thread guide, wherein the drive drum has acceleration phases which are each followed directly by a deceleration phase,
characterized,

• the drive drum has a higher peripheral speed during the acceleration and deceleration phases than the cross-wound bobbin,
• that the deceleration phases are ended at the time at which the peripheral speed of the drive drum has dropped to that of the cross-wound bobbin,
• and that each of the deceleration phases is followed by a synchronization phase in which the peripheral speeds of the drive drum and cross-wound bobbin are the same.

• eine mit Kehrgewinderillen für die Fadenführung versehene Antriebstrommel zum Antrieb der Kreuzspule,
• einen oder mehrere Sensoren zur Bereitstellung von Signalen zur Ermittlung der Umfangsgeschwindigkeiten von Antriebstrommel und Kreuzspule, und
• eine mit dem einen oder den mehreren Sensoren verbundenen Steuereinheit zur Berechnung der Umfangsgeschwindigkeiten von Antriebstrommel und Kreuzspule aus den Signalen des einen oder der mehreren Sensoren und zur Steuerung der Umfangsgeschwindigkeit der Antriebstrommel,

wobei die Steuereinheit zum Betreiben der Antriebstrommel in Beschleunigungsphasen, die jeweils von einer Abbremsphase unmittelbar gefolgt werden, vorgesehen ist,
dadurch gekennzeichnet, dass die Steuereinheit dazu vorgesehen ist,

• die Antriebstrommel während der Beschleunigungs- und Abbremsphasen mit einer höheren Umfangsgeschwindigkeit als die Kreuzspule zu betreiben,
• die Abbremsphasen in dem Zeitpunkt zu beenden, in dem die Umfangsgeschwindigkeit der Antriebstrommel auf die der Kreuzspule gesunken ist,
• und die Antriebstrommel jeweils nach einer Abbremsphase in einer Gleichlaufphase zu betreiben, in der die Umfangsgeschwindigkeiten von Antriebstrommel und Kreuzspule gleich sind.

However, the object is also achieved by a device for avoiding image windings when winding a cross-wound bobbin, comprising

• a drive drum provided with reverse thread grooves for the thread guide for driving the cross-wound bobbin,
• one or more sensors for providing signals for determining the peripheral speeds of the drive drum and cross-wound bobbin, and
• a control unit connected to the one or more sensors for calculating the peripheral speeds of the drive drum and cross-wound bobbin from the signals of the one or more sensors and for controlling the peripheral speed of the drive drum;

wherein the control unit is provided for operating the drive drum in acceleration phases which are each directly followed by a deceleration phase,
characterized in that the control unit is intended to

• operate the drive drum at a higher peripheral speed than the cheese during the acceleration and deceleration phases,
• to terminate the deceleration phases at the time when the peripheral speed of the drive drum has dropped to that of the cross-wound bobbin,
• and the drive drum each after a deceleration phase in a synchronous phase to operate, in which the peripheral speeds of the drive drum and cross-wound bobbin are the same.

The inventor has recognized that compared to the EP 0 399 243 B1 a sufficient or even improved image disturbance can be achieved even if you shorten the deceleration phase of the drive drum so that you from the time in which the peripheral speed of the drive drum has fallen to the cheese, replaced by a non-driven freewheel, from this point in time the deceleration phase replaced by a synchronization phase. Because unlike in the EP 0 399 243 B1 In the opinion that synchronous phases should be completely avoided, the inventor has realized that synchronized phases of limited length are perfectly acceptable.

By synchronizing phases arranged according to the invention but is compared with the EP 0 399 243 B1 avoided that the peripheral speed of the drive drum drops below that of the cheese, which on the one hand saves the necessary energy consumption for then entering braking the cheese and on the other hand also avoids the energy consumption for subsequently in the acceleration phase again becoming necessary accelerating the cheese to its peripheral speed before braking. The energy consumption of the method according to the invention is therefore lower than that in the EP 0 399 243 B1 proposed method. In addition, by the fact that the peripheral speed of the drive drum never falls below that of the cheese, largely avoided that the thread must be pulled under high friction between cheeses and drive drum, which reduces the risk of yarn breaks.

Preferably, the sequences according to the invention from acceleration, deceleration and synchronization phases can be followed directly one after the other, ie the entire drive can be composed of these phases. However, this is not mandatory, since alternatively these phases can only occasionally, for example, at the diameters critical for the images of the cheese, can be used, while otherwise the drive drum can be operated for example at a constant peripheral speed. Again, this can give acceptable image disturbances in certain situations. As in the EP 0 399 243 B1 In addition, the parameters of the phases in Depending on the current diameter of the cheese to be varied, so for example, the time periods of the individual phases and their acceleration or deceleration forces are selected depending on the diameter.

Advantageously, the periods of acceleration and deceleration phases may be determined by terminating the acceleration phases at the time when the peripheral speed of the drive drum reaches an upper limit speed and terminating the synchronization phases at the time when the peripheral speed of the drive drum stops reached lower limit speed. This has the advantage that excessive fluctuations in the peripheral speed of the drive drum and thus that of the cross-wound bobbin can be safely avoided.

Particularly simple conditions in the acceleration and deceleration phases result in specialization of the method that the drive drum is accelerated during the acceleration phase by a constant acceleration torque that the drive drum is decelerated during the deceleration phase by a constant deceleration torque, and that the drive drum during the synchronization phase is not applied with a torque.

Finally, a particularly simple use of the method for the operator results from the fact that the acceleration torque is determined such that at a predetermined by a user of the method ratio of acceleration to deceleration predetermined by the user of the method braking phase ratio (v _o - v _bg ) / (v _o -v _u ), where v _{o is} the upper limit speed, v _{u is} the lower limit speed, and v _{bg is} the peripheral speed of the drive drum at the transition from the brake to the synchronization phase. By specifying the brake phase ratio can be set directly the proportion of the braking phase. The smaller the braking phase ratio, the shorter the braking phase and the lower the energy requirement of the process. Once the limit speeds have been selected, the braking phase ratio should be chosen as small as possible from an energy saving point of view, that is, with an acceptable picture disturbance.

The determination of the acceleration torque BD _ges to the predetermined braking _{phase ratio} BPV _vorg can eg iteratively be done by starting from a standard acceleration torque BD _St and the _{brake phase ratio} BPV _St at BD _St measures. If BPV _St > BPV _vorg , one reduces the acceleration torque by a certain amount, which corresponds to the desired accuracy for torque determination. This is iterated until the predetermined _{brake-phase ratio} BPV is approached. At BPV _St <BPV _vorg one increases the acceleration torque in a corresponding manner.

To implement the method, a device according to the invention, which may be in particular a winding unit of a winding machine or a spinning machine and the latter in particular an open-end spinning machine, hardware only the usual known components, while the procedures can be stored as software in a control unit of the device. In the case of a textile machine, this control unit can be separately attached to each of these workstations or centrally on the textile machine and can also perform other independent of the invention control tasks.

To determine the peripheral speeds of the drive drum and cheese, the known and, for example, also in EP 0 399 243 B1 described angular velocity sensors in connection with also known and in EP 0 399 243 B1 described diameter regulations of the cheese (over average ratio of the angular velocities of cheeses and drive drum, optically light source and photocell assembly, angular position of the coil frame) are used. However, because of the higher accuracy, to determine the peripheral speed of the cross-wound bobbin, a direct measurement of the thread speed by a sensor which is traversed by the thread and based for example on the cross-correlation or the LDA principle. For this purpose, the thread speed is converted over the expert well-known relationships in the winding speed.

All of the embodiments described above and also their combinations belong to the present invention.

In the following the invention with reference to an embodiment shown in the drawings and some of its variants will be explained in more detail.

Fig. 1

in Vorderansicht eine vereinfachte Darstellung einer erfindungsgemäßen Vorrichtung, konkret einer erfindungsgemäß eingerichteten Spulstelle einer Spulmaschine;

Fig. 2

die Spulstelle aus Figur 1 in Seitenansicht;

Fig. 3

schematisch eine Sequenz aus Beschleunigungs-, Abbrems- und Gleichlaufphase;

Fig. 4a und 4b

zwei Messkurven des Energieverbrauchs beim erfindungsgemäßen Wickeln einer Kreuzspule;

wobei dieselben Bauteile in allen Figuren mit denselben Bezugszeichen bezeichnet sind.Show it

Fig. 1

in front view a simplified representation of a device according to the invention, specifically a winding unit of a winding machine according to the invention;

Fig. 2

the winding unit off FIG. 1 in side view;

Fig. 3

schematically a sequence of acceleration, deceleration and synchronization phase;

Fig. 4a and 4b

two traces of energy consumption when winding a cross-wound bobbin according to the invention;

wherein the same components in all figures are denoted by the same reference numerals.

In the essence of the EP 0 399 243 B1 taken and there as Figures 2 and 5 shown Figures 1 and 2 are schematically illustrated in front and side view simplified according to the invention a winding unit 1 of a winding machine.

At the winding station 1, a cross-wound bobbin 8 mounted in a coil holder 9 is driven by a drive drum 2 by means of friction. In this case, a withdrawn from a cop 28 thread 7 is wound on the cheese 8. This thread 7 is laid by means of a Kehrgewinderille 2 "of the drive drum 2 parallel to the axis of the cheese 8. This creates the desired Kreuzbewicklung.

The drive drum 2 is mounted on a drum shaft 2 'in the machine frame 3 of the winder. The drive of the drum shaft 2 'takes place via pulleys 4 and 4' connected by a V-belt 4 ', wherein the pulley 4' is driven by an electric motor 6 'but instead of being mediated by the belt drive 4, 4', 4 " possible and now widespread that an electric motor 6 'drives the drum shaft 2' directly. This electric motor 6 ', in 4-quadrant operation is controlled, is controlled by an inverter 16, which receives its control commands via a control line 15 'from a spool's own control unit 14.

The information about the peripheral speeds of drive drum 2 and cheese 8 receives the control unit 14 of sensors 12, 10 and 31. For this purpose, the sensors 12 and 10, which are for example responsive to the rotation angle, measure and transmit the angular velocities of the drive drum 2 and cross-wound bobbin 8 Lines 11 and 13 to the control unit 14 on, which can then calculate the circumferential speed of the known diameter of the drive drum 2 immediately. The sensor 31 measures the angular position of a coil frame 29, which carries the coil holder 9 and in turn is mounted in a coil frame axis 30. Its signal is given by the sensor 31, e.g. can be designed as a rotational resistance, via a line 32 to the control unit 14, which then calculates the diameter of the cheese 8 from the angular position of the coil frame 29 and with the transmitted from the sensor 10 angular velocity then the peripheral speed of the cheese 8.

Alternatively, and because of the higher accuracy preferred, however, the peripheral speed of the cheese 8, as already mentioned, also by a direct measurement of the yarn speed by a sensor which is traversed by the yarn and e.g. based on the cross-correlation or LDA principle. For this purpose, the thread speed is then converted into the circumferential speed of the cross-wound bobbin 8 by means of connections well-known to those skilled in the art.

In simpler machines, where one wants to limit the sensor effort, it is also possible to dispense with the measurement of the thread speed and also on the measurement of the angular position of the coil frame 29. For this purpose, one switches off the drive of the drive drum 2 temporarily, which is part of many common Bildstörverfahren anyway. If this shutdown persists long enough, the cross-wound bobbin 8 will eventually assume the same peripheral speed as the drive drum 2 because of its frictional engagement with the drive drum 2, that is to say enter a slip-free operation.

In this slip-free operation, the instantaneous diameter of the cross-wound bobbin 8 can then be determined from the angular speeds of the drive drum 2 and cross-wound bobbin 8 as well as the known diameter of the drive drum 2. In the simplest variant, one can then view this diameter as constant until the next diameter determination in the next slip-free phase and calculate the peripheral speed of the cheese 8 with this diameter from its angular velocity. In more specific variants, however, the increase in diameter can also be calculated over the known angular speed of the cheese 8 over time, if the other known variables such as thread diameter and, for example, the yarn diameter are used. Traversing speed of the cross winding used.

Also shown are a thread monitor 26 which is arranged in the course of the yarn 7 and which is likewise connected to the control unit 14 via a line 27. This thread monitor 26 indicates the absence of the thread 7, that is, a thread break, on, the control unit 14 via the control line 15 'and the inverter 16, the electric motor 6' de-energized.

The inventive method can be, for example, with otherwise unchanged use of known components, such as in Figures 1 and 2 illustrated by realizing a change in the running in the control unit 14 software. This software then provides for an inventive temporal sequence of acceleration, deceleration and synchronization phase, which is also referred to as Bildstörzyklus BZ and schematically in FIG. 3 is shown as a representation of the evolution of the peripheral velocities v with respect to the time t.

The acceleration phase BP starts here from a substantially synchronous state, ie from a state in which the peripheral speed v _{Tr of} the drive drum 2 and substantially also the peripheral speed v _{Kr of} the cheese 8 are equal to the lower limit speed v _u . Then, the electric motor 6 'is applied via the inverter 16 with a constant positive current, for example, 1.76 A, to the end of the acceleration phase BP, which is achieved when the peripheral speed v _{Tr of} the drive drum 2 reaches the upper limit speed v _o , Due to their inertia and the limited frictional coupling of the cheese 8 to the drive drum 2 can in the acceleration phase BP, the cheese 8 the drive drum 2 follow only delayed, the peripheral speed v _{Kr of} the cheese 8 is thus always below the peripheral speed v _{Tr of} the drive drum 2. In other words, between these two speeds, a slip S builds up.

As soon as the peripheral speed v _{Tr of} the drive drum 2 reaches the upper limit speed v _o , the acceleration phase BP changes over to the deceleration phase AP. Now, the electric motor 6 'is supplied via the inverter 16 with a constant negative current, eg -0.64 A, until the end of the deceleration phase AP, which is reached when the peripheral speeds v _{Tr of} the drive drum 2 and v _{Kr of} the cross-wound bobbin 8 assume the same value as in FIG. 3 is designated as v _bg . During the deceleration phase AP, the peripheral speed v _{Kr of} the cross drum 8 thus continues to increase, but at an increasingly slower rate, while the peripheral speed v _{Tr of} the drive drum 2 decreases due to the braking. As soon as the two circumferential speeds v _Tr and v _{Kr become} equal: v _Tr = v _Kr = v _bg , the control unit 14 terminates the deceleration phase AP and initiates the synchronization phase GP by switching the motor 6 'de-energized.

In the following synchronization phase GP, the drive drum 2 and the package 8 slower due to their inertia, the frictional engagement between them ensuring that their circumferential velocities v _TR and v _Kr remain essentially the same. The control unit 14 terminates the synchronization phase GP as soon as the peripheral speed v _{Tr of} the drive drum 2, and thus also substantially the peripheral speed v _{Kr of} the cheese 8, reaches the lower limit speed v _u .

After that, the next image disturbance cycle BZ consisting of acceleration phase BP, deceleration phase AP and synchronization phase GP is then started immediately, ie the image disturbance cycles BZ are preferably repeated periodically immediately after one another. Alternatively, however, it is also possible to insert phases of constant peripheral speed v _{Tr of} the drive drum 2 between the frame noise cycles BZ by applying a current corresponding to that below the acceleration phase current to the motor 6 '. Here it may then be useful to end the synchronizing phase already when the peripheral speed v _{Tr of} the drive _drum 2 reaches the mean velocity v _M = (v _o + v _u ) / 2, then the peripheral speed v _Tr of Drive drum 2 at the center speed v _M for a certain time to keep constant: v _Tr = v _M. However, as soon as the diameter of the cross-wound bobbin 8 gets into an area which is endangered by the formation of images, the image disturbance cycles BZ according to the invention should be used again.

For the operating personnel of the winder, it makes sense to control the method by specifying the center speed v _M and the speed hysteresis Δv = v _o - v _u ; because the center speed v _M will be only slightly above the mean winding speed achieved during the winding of the cheese 8, ie the average peripheral speed <v _Kr > of the drive drum 2, which is of prime importance as a productivity parameter for the operator. Further, the velocity hysteresis Δv can be intuitively expressed as a percentage of the center velocity v _M , which percentage should not be set too high, since the upper limit velocity v _{o is} mainly limited by thread breaks, while the center velocity should be as high as possible because of the high productivity aimed for , Typical values are: v _M = 1,200 m / min; Δv = 9% · v _M = 108 m / min, and thus v _u = 1,146 m / min and v _o = 1,254 m / min.

As in a preferred embodiment, the ratio of acceleration to deceleration torque, in the embodiment of FIG Figures 1 and 2 Thus, the ratio of acceleration and deceleration current, kept constant, so the length of the deceleration phase by the operator by specifying the brake phase ratio BPV = (v _o - v _bg ) / (v _o - v _u ) specify. Typical values for BPV are 15% and 10%.

The influence of the brake-phase ratio BPV on the energy consumption in winding a cheese was experimentally investigated and is shown by way of example in FIGS. 4a and 4b, where the energy consumption in Ws / km of coiled yarn length is plotted against the diameter of the cheese in mm. At the beginning of the coil travel, ie at small cross-coil diameters, this energy consumption is very large, but then decreases rapidly towards a saturation value approximately in hyperbolic form. The outliers of individual measurement points from the general curve trace back to thread breaks and have no significance for the basic energy consumption.

The two measurement curves are based on the same conditions apart from the brake-phase ratio BPV: v _M = 1,200 m / min; Δv = 9% · v _M = 108 m / min, and thus v _u = 1,146 m / min and v _o = 1,254 m / min. It was a modern, lightweight and ball-bearing drive drum used. For the trace in Fig. 4a Then, a brake-phase ratio BPV of BPV = 15% was used, corresponding to a peripheral speed of the drive drum at the end of the braking phase of v _Tr = v _bg v ₀ -BPV * Δv = (1.254-15% × 108) m / min = 1237.80 m / min while for the trace in Fig. 4b a BPV of BPV = 10% was used, corresponding to v _bg = (1.254-10% × 108) m / min = 1.243.20 m / min.

As already mentioned, a smaller braking phase ratio leads to a shortening of the braking phase. This is explained by the fact that the then used lower acceleration torque during the acceleration phase leads to a smaller slip between the drive drum and cross-wound bobbin whose peripheral speeds differ at the end of the acceleration phase thus only by a smaller amount. In the subsequent deceleration phase, therefore, only a smaller difference in speed must be decelerated, which leads to a shortening of the deceleration phase even if the deceleration torque is proportionally reduced.

However, a shorter deceleration phase and a correspondingly extended synchronization phase costs less energy. In addition, there is the reduced slip during the acceleration phase, which also saves energy, since greater slippage leads to more friction and thus energy consumption.

This manifests itself in the to the FIGS. 4a and 4b associated measured data of the wound cheeses and the energy required for this: BPV = 15% ( Fig. 4a ) BPV = 10% ( Fig. 4b ) Wound thread length [m] 82192 95293 Duration of the winding process [s] 4187 4851 Mean velocity <v _kr > [m / min] 1,177.64 1,178.43 Energy consumption [Wh] 77.4 84.4 Average energy consumption via coil travel [Ws / km] 3390 3187

It is therefore clear that with an almost identical average winding speed of <v _Kr > ≈ 1,178 m / min, the energy consumption at a brake-phase ratio of BPV = 10% compared to a brake-phase ratio of BPV = 15% drops significantly by 6%.

Although the image disturbance method according to the invention and its associated device have been described above with reference to selected exemplary embodiments, further variants as well as combinations of the specific embodiments described are conceivable for the person skilled in the art. For example, Acceleration and deceleration torques can not be varied in a constant ratio, but can also be optimized separately.

Further, for the sake of completeness, it should be pointed out that the indefinite article does not exclude that components designated by it can not also be present multiple times. Likewise, the description of a particular component does not necessarily mean that its functions could not be distributed among several alternative components, or that the functions of several described components could not be grouped together.

Claims (8)

A method of avoiding image windings when winding a cross-wound bobbin (8) driven by a drive drum (2) provided with reverse thread grooves (2 ") for the yarn guide, the drive drum (2) having acceleration phases (BP) each of a deceleration phase (AP) be followed immediately,
characterized, - That the drive drum (2) during the acceleration (BP) and Abbremsphasen (AP) has a higher peripheral speed than the cheese (8), - That the Abbremsphasen (AP) are terminated at the time in which the peripheral speed of the drive drum (2) has fallen to that of the cheese (8), - And that the deceleration phases (AP) are each followed by a synchronization phase (GP), in which the peripheral speeds of the drive drum (2) and cheese (8) are the same. A method according to claim 1, characterized in that the sequences of acceleration (BP), deceleration (AP) and synchronization phases (GP) adjoin one another directly. Method according to claim 1 or 2, characterized - That the acceleration phases (BP) are terminated at the time in which the peripheral speed of the drive drum (2) reaches an upper limit speed (v _o ), - And that the synchronizing phases (GP) are terminated at the time in which the peripheral speed of the drive drum (2) reaches a lower limit speed (v _u ). Method according to claim 3, characterized that the drive drum (2) is accelerated during the acceleration phase (BP) by a constant acceleration torque, - That the drive drum (2) during the deceleration phase (AP) is decelerated by a constant deceleration torque, - And that the drive drum (2) is not applied during the synchronization phase (GP) with a torque. A method according to claim 4, characterized in that the acceleration torque is determined such that at a predetermined by a user of the method ratio of acceleration to deceleration predetermined by the user of the method braking phase ratio (v _o - v _bg ) / (v _o - v _u ), where v _o for the upper limit speed, v _u for the lower limit speed and v _bg for the peripheral speed of the drive drum (2) at the transition from the brake (BP) to the synchronization phase (GP) are. Device for avoiding image windings when winding a cross-wound bobbin (8), comprising a drive drum (2) provided with reverse thread grooves (2 ") for the thread guide for driving the cross-wound bobbin (8), - One or more sensors (12, 10, 31) for providing signals for determining the peripheral speeds of the drive drum (2) and cross-wound bobbin (8), and - a control unit (14) connected to the one or more sensors (12, 10, 31) for calculating the peripheral speeds of the drive drum (2) and cross-wound bobbin (8) from the signals of the one or more sensors (12, 10, 31 ) and for controlling the peripheral speed of the drive drum (2), wherein the control unit (14) is provided for operating the drive drum (2) in acceleration phases (BP) which are each directly followed by a deceleration phase (AP),
characterized,
that the control unit (14) is intended to to operate the drive drum (2) at a higher peripheral speed than the cheese (8) during the acceleration (BP) and deceleration phases (AP), to terminate the deceleration phases (AP) at the time at which the peripheral speed of the drive drum (2) has dropped to that of the cross-wound bobbin (8), - And the drive drum (2) in each case after a deceleration phase (AP) in a synchronous phase (GP) in which the peripheral speeds of the drive drum (2) and cross-wound bobbin (8) are the same. Device according to claim 6, characterized in that - That the one or more sensors comprise a sensor which is intended to be traversed by a on the cheese (8) to be wound thread (7) and thereby to measure the speed of the thread (7), - And that the control unit (14) is provided to determine from the speed of the thread (7) obtained from this sensor, the peripheral speed of the cheese (8). Apparatus according to claim 6 or 7, characterized in that it is the device to a winding unit (1) of a winder or a spinning machine.

Images