EP0349939B1 - Method for changing bobbins - Google Patents

Description

The invention relates to a method for changing bobbins when winding up a thread starting at a constant speed according to the preamble of claim 1.

This method is known from DE-PS 24 61 223, DE-PS 32 11 603. The empty sleeve has a catch groove in a normal plane which lies to the side of the traversing area. To insert the thread into the catch groove, the thread must therefore be guided in this normal plane. The traversing speed must therefore be suspended. Therefore, the thread piece between the empty tube and the upstream delivery mechanism is very relaxed, which can lead to the thread forming a winder on the delivery mechanism. In addition, at the moment of catching, the empty tube is driven in such a way that the empty tube and the thread have opposite speeds in the peripheral region in which they touch.

In particular, man-made fibers in spinning plants come into consideration as continuously starting threads.

The object of the invention is to eliminate this Verschlappungsekkekt or to eliminate so far that the risk of disturbing the bobbin change, in particular the risk of winder formation on the upstream delivery mechanism is eliminated.

The solution results from the characterizing part of claim 1.

The reduction in the traversing speed is stronger, and much more than is usually the case when producing a precision winding. After this reduction, the deposit angle alpha is less than / equal to 4 °, preferably less than / equal to 3 °.

With this solution, the jump by which the thread tension drops during thread catching is considerably reduced. The overall reduction in the winding speed from normal operation to thread catching is the same. However, it has been found that the sudden drop in thread tension and the amount of this jump are responsible for the disruption of the winding process.

The traversing speed is reduced continuously or at most in small steps, and within a very short time in relation to the total winding time (winding travel) of a full package, preferably with a winding layer thickness of not more than 1 mm.

In an embodiment of the invention, care is also taken to ensure that the thread relaxation between normal operation and thread catching is kept as low as possible with the steady or gradual reduction in the traversing speed. This embodiment results from claim 2 with a preferred further development according to claim 3. In the method according to claim 3, when the traversing is suspended, the previously increased thread tension is lowered below the desired value.

In a further embodiment of the invention, it is possible to completely avoid this thread relaxation (thread entanglement). This embodiment results from claim 4 or 5.
In the embodiment of this method according to claim 5 it can be achieved that the thread tension does not drop below its setpoint.

The occurring according to claim 3 to 5, brief increase in thread tension is not unfavorable winding technology, since it leads to the fact that some tightly wound thread layers are deposited on the full bobbin, which increase the stability of the full bobbin.

As already said, it has been found that the sudden dumping is responsible for the disruption of the winding process. Therefore, the jump by which the thread tension decreases when catching the thread must not become too large. Limits are given in claim 6. This means that the deviation between the winding speed and the peripheral speed of the bobbin, which is maintained during the winding travel, should not be greater than 0.5% or 0.2%.

The method for changing bobbins according to this invention advantageously integrates into the overall winding process. On the one hand, final thread layers are formed on the full bobbin, which have only a small crossing angle and therefore do not tend to slide axially inwards. On the other hand, these thread layers are wound very tightly, so that they form a covering layer for the thread layers lying further inside. In addition, however, the traversing speed reduced according to this invention is particularly suitable for winding the new spool.

From claim 7 and the development according to claims 8 and 9, the manner in which the method for changing bobbins according to this invention is integrated into the winding process for forming a new bobbin.

This process forms a base layer when the new coil is wound, which has a slightly larger width than the other coil layers and which has slightly conical side edges. This gives the rest of the coil a better grip. Details of this winding method can be found in EP-A 87111025 and EP-A 87111210.

From DE-PS 32 11 603 it is already known that by increasing the distance between the full bobbin there is a reduction in the laying length with which the thread is deposited on the full bobbin. Claim 10 proposes to combine this effect with the strong reduction in the traversing speed in such a way that the thread still running towards the full bobbin cannot fall off the side of the full bobbin.

This process can - as suggested by claim 11 - advantageously be connected to the first phase of the bobbin changing process if the method is applied to winding machines in which of two spindles alternately one is in operation and the other is in a waiting position.

The reduction of the distance between the traversing device and the reel to be formed after the bobbin change should - as proposed according to claim 12 - take place when the traversing has been used again, but before the traversing speed is increased again from its reduced value. As a result, the formation of a widened base layer, as desired according to the European applications mentioned, can be further reinforced.

The invention is described below using exemplary embodiments.

Fig. 1

die Schemazeichnung einer Aufwickelmaschine;

Fig. 2-6

den Verfahrensablauf des Spulenwechsels;

Fig. 7-9

Geschwindigkeitsdiagramm des Spulenwechsels.

Show it

Fig. 1

the schematic drawing of a rewinder;

Fig. 2-6

the procedure of changing the bobbin;

Fig. 7-9

Speed diagram of the bobbin change.

The winding device consists of the traversing device with reversing thread shaft 2 and traversing thread guide 3. The traversing thread guide 3 is guided back and forth in the grooves 4 of the reversing thread shaft and straight in the straight guide 5. Through the traversing thread guide 3, the thread 6 is laid on the winding tube 7 to form a package 8. The sleeve 7 is firmly clamped on the winding spindle 9.1. The winding spindle 9.1 is driven in the direction of rotation 10 by the spindle motor 20.1. During the winding process, the second winding spindle 9.2 with the sleeve 7 clamped thereon is in the waiting position. The auxiliary thread guide 11, which will be described later, is also still in the waiting position. The winding spindle 9.2 can be driven by a spindle motor 20.2. The traversing motor 31 is used to drive the traversing. The motors 31; 20.1; 20.2 can be started by programmable control device 30 independently of one another, put out of operation and controlled in their speed.

During the regular winding operation, the spindle speed decreases steadily because the thread speed remains constant while the bobbin diameter increases. The traversing speed, on the other hand, remains essentially constant (wild winding) or changes only within narrowly defined limits (step precision winding).

The coils can also be driven by the deflecting roller. In this case, the deflection roller lies on the surface of the spool and is driven at a constant speed.

2, which is rotatable about the axis of rotation 19, the winding spindles 9.1 and 9.2 are freely rotatable and cantilevered. The traversing device also includes the deflection roller 21, which is partially wrapped around by the thread 6 and which either rests on the spool or only a very small one with the spool Gap forms, so that the drag length L1 of the thread between the deflection roller and the bobbin is very small. The traversing devices are mounted on a carriage 22 that is movable in the vertical direction and sketched in FIG. 2. Details of the traversing device shown result, for example, from DE-PS 20 40 479 and 23 45 898.
However, it is only an example. Other types of traversing devices are also conceivable, cf. for example EP 114 642 (EP-1321).

After or shortly before the winding process is completed, i.e. when the bobbin 8 is almost full, the center distance between the deflection roller 21 and the full bobbin is first increased for the purpose of changing the bobbin, so that the deflection roller 21 completely releases the full bobbin 8.1. In the example shown, this takes place in that the carriage 22 is raised with the direction of movement 23. Now the carrier 18 - as shown in FIG. 4 - is rotated in the direction of movement 24 until the winding spindle 9.2 with the empty tube 7.2 stretched thereon gets into the thread path. As a result, the drag length L2 between the run-off point of the thread from the grooved roller and the run-up point of the thread on the full bobbin 8.1 has been considerably increased and the laying stroke has been reduced accordingly. Synchronously with this, the winding spindle 9.2 is moved with the clamped empty winding tube (empty tube 7) in the direction of arrow 24 into the plane of the thread path in the final state shown in FIG. 5.

.By increasing the drag length from L1 to L2, the laying stroke H, which is predetermined by the traversing stroke CH of the thread guide 3, ie the spool length is reduced to the laying stroke H2. This reduced laying stroke H2 makes it possible to axially shift the winding spindle 9.1 with the direction of movement 15 by the amount A without the thread still located in the traversing device falling off the surface of the bobbin. A is less than $\text{h = H - H2 / 2}$

.

It should only be emphasized for the sake of completeness that the winding spindle 9.2 with the empty tube 7 remains in its original position when the thread is changed, that is to say is not axially displaced.
Now the winding spindle 9.1 is axially displaced in the direction 15 such that, for example, the left end face of the full bobbin 8.1 approximately coincides with the left end of the shortened laying stroke.

The axial displacement of the winding spindle 9.1 creates a distance B between the right end face of the full cheese 8 and the right end face of the new laying stroke H2, B being greater than h but less than 2h.

Now the auxiliary thread guide 11 is folded out of the position shown in broken lines in FIG. 1 into the thread running plane of the thread run 6. The thread is thereby lifted out of the traversing thread guide 3 and caught in the thread guide slot 56. By moving the auxiliary thread guide in the direction of arrow 16 - as shown in FIG. 1 - the thread is brought out of the area of the traversing stroke CH, just above the catch slot 17 provided in each sleeve 7, but not beyond the normal plane of the right end face the full cheese 8 in its axially displaced position. For this purpose, reference is made to FIG. 1. The movement length C of the auxiliary thread guide 11 over the right edge of the normal laying stroke H - indicated on the chuck 9.2 in dashed lines - is accordingly greater or at most equal to the distance that the catch slot 17 has from the right end of the normal laying stroke H. However, the movement length C is less than the amount A of the axial displacement of the winding spindle 9.1. This ensures that - as shown in Fig. 1 - the thread can be brought into the normal plane of the catch slot, but also does not fall off the circumference of the full bobbin 8 and is still wound onto the full bobbin during the catch and through the full coil is promoted.

The catching device for textile threads is preferably attached as a slot on the circumference of the sleeve 7 and is located somewhat outside the winding area H. In the area of the normal plane in which this slot lies, the auxiliary thread guide 11 leads a very slow axial movement in and through the normal plane of the Catch slot so that the thread is caught safely. Now the auxiliary thread guide 11 is moved back at high speed into the area of the normal traverse stroke, so that - as can be seen in FIG. 1 - only a few turns of a thread reserve winding 26 are applied between the catch slot 17 and the right end side of the normal winding area H. As soon as the auxiliary thread guide 11 has reached the traversing area CH again, it is brought back into its starting position, so that the thread is caught again by the traversing devices and moved to a package. Now the winding spindle 9.2 or the empty tube clamped thereon and the slide 22 are moved back into their starting position, the carrier 18 being rotated further accordingly. The operating position for the winding spindle 9.2 is shown in FIG. 6.

In Fig. 6 it is shown that the carriage 22 is now lowered again. Deviating from the previous figures, it is shown here that the drive can also take place during winding, that is to say in normal operation, by a drive roller 20 which is driven at a constant circumferential speed and which is fastened on the carriage 22. In this case, the drive motors 20.1, 20.2 are switched off during normal winding operation.

FIGS. 7 to 9 show speed diagrams of the bobbin change. The process sequences proposed according to this invention are described on the basis of these speed diagrams.

VU

Umfangsgeschwindigkeit der Leerhülse und der darauf gebildeten Spule (beim Aufwickeln von Chemiefasern sind z.B. Umfangsgeschwindigkeiten von 5.000 m/min möglich;)

VUW

Umfangsgeschwindigkeit während des Spulenwechsels

VC

Changiergeschwindigkeit (beim Aufwickeln von Chemiefasern mit einer Spulenumfangsgeschwindigkeit von 5.000 m/min beträgt zur Herstellung eines Kreuzungswinkels von z.B. 8° die Changiergeschwindigkeit 700 m/min.
Es sei bemerkt, daß zur Vermeidung der Spiegelbildung bzw. zur Beseitigung der Spiegelbildung die Changiergeschwindigkeit üblicherweise während der Spulreise nicht konstant bleibt, sondern nach bestimmten Programmen um einen Mittelwert herum oder innerhalb vorgegebener Bereiche verändert wird. Diese Änderungen sind im Rahmen dieser Erfindung ohne Bedeutung und in dieser Anmeldung außer Acht gelassen. Im Rahmen dieser Anmeldung ist die Changiergeschwindigkeit als die mittlere Changiergeschwindigkeit definiert.)

VCW

Changiergeschwindigkeit während des Spulenwechsels

VF

Fadengeschwindigkeit (die Fadengeschwindigkeit ist die geometrische Summe der Umfangsgeschwindigkeit und der Changiergeschwindigkeit. Bei einer Umfangsgeschwindigkeit von 5.000 m/min und einer Changiergeschwindigkeit von 700 m/min ergibt sich mithin eine Fadengeschwindigkeit von 5.050 m/min. Hieraus ergibt sich, daß beim Aussetzen der Changierung die Fadengeschwindigkeit um fast 1% abnimmt.)
Die Fadengeschwindigkeit VF ist die Geschwindigkeit, mit der der Faden aufgespult wird. Diese Geschwindigkeit ist im wesentlichen identisch mit der Geschwindigkeit, mit welcher der Faden angeliefert wird. Die Lieferwerke, die den Faden mit konstanter Geschwindigkeit anliefern, sind in den Figuren 1 bis 5 nicht dargestellt. Es handelt sich um übliche Galetten.
Es besteht eine gewisse Differenz zwischen der Fadengeschwindigkeit und der Liefergeschwindigkeit. Diese Differenz wird so ausgewählt, daß der Faden mit einer gewünschten Soll-Fadenspannung auf der Spule aufgewikkelt wird. Diese Differenz ist nicht identisch mit der nachfolgenden Größe DV. Wenn vielmehr DV größer wird als die Differenz zwischen der Liefergeschwindigkeit und dem Sollwert der Faden-Aufwickelgeschwindigkeit, so geht die Fadenspannung gegen Null und es tritt "Verschlappung" des Fadens ein mit der Gefahr der Wicklerbildung an dem Lieferwerk.

DV

Differenz der Aufwickelgeschwindigkeit zwischen dem Sollwert der Fadengeschwindigkeit VF und der in der Wechselphase bestehenden Aufwickelgeschwindigkeit

alpha

= Kreuzungswinkel (Winkel zwischen dem auf der Spule abgelegten Faden und einer den Faden schneidenden Tangente an die Spule.)

alpha_w

= Kreuzungswinkel während der Wechselphase.

Mean in the speed graphs

VU

Circumferential speed of the empty tube and the spool formed on it (circumferential speeds of 5,000 m / min are possible, for example, when winding man-made fibers;)

VUW

Circumferential speed during the bobbin change

VC

Traversing speed (when winding man-made fibers with a spool circumferential speed of 5,000 m / min, the traversing speed is 700 m / min to produce a crossing angle of 8 °, for example.
It should be noted that in order to avoid mirror formation or to eliminate mirror formation, the traversing speed does not usually remain constant during the winding travel, but is changed according to certain programs around an average value or within predetermined ranges. These changes are irrelevant in the context of this invention and are ignored in this application. In the context of this application, the traversing speed is defined as the mean traversing speed.)

VCW

Traversing speed during the bobbin change

VF

Thread speed (the thread speed is the geometric sum of the circumferential speed and the traversing speed. With a circumferential speed of 5,000 m / min and a traversing speed of 700 m / min, a thread speed of 5,050 m / min results. This means that when the traversing is suspended the thread speed decreases by almost 1%.)
The thread speed VF is the speed at which the thread is wound up. This speed is essentially identical to the speed at which the thread is delivered. The delivery mechanisms that deliver the thread at a constant speed are not shown in FIGS. 1 to 5. They are common godets.
There is a certain difference between the thread speed and the delivery speed. This difference is selected so that the thread is wound onto the bobbin with a desired nominal thread tension. This difference is not identical to the following size DV. If, on the contrary, DV becomes greater than the difference between the delivery speed and the nominal value of the thread winding speed, then the thread tension goes to zero and "threading" of the thread occurs with the risk of winder formation at the delivery mechanism.

DV

Difference of the winding speed between the nominal value of the thread speed VF and the winding speed existing in the change phase

alpha

= Crossing angle (angle between the thread deposited on the bobbin and a tangent to the bobbin that intersects the thread.)

alpha _w

= Crossing angle during the change phase.

Regarding the diagrams, it should be noted that the speeds and times are not drawn to scale.

In all diagrams according to FIGS. 7 to 9, a bobbin changing method is shown in which the traversing speed VC is greatly reduced before the traversing is suspended.

In operating phase I, in which the bobbin is wound up with its target conditions, the mean value of the traversing speed is constant. As a result, the peripheral speed and the traversing speed add up to the constant value of the thread speed VF.

At the end of the winding cycle, the traversing speed can be reduced slightly (approx. 10 to 20%) in a phase II. This changes the crossing angle. This reduction is known per se and is not the subject of this application. Phase II is therefore not part of changing the bobbin, but part of the usual winding trip.

It is also known from EP 93 258 to reduce the traversing speed at the end of the winding cycle proportionally with the decreasing speed of the winding spindle, even in the case of a wild winding to avoid mirrors which occur at the end of the winding cycle. This creates a precision winding in the last phase of the winding cycle. This reduction in the traversing speed is also very small and is not more than 10 to 20%.

This relatively slight reduction in the traversing speed in phase II does not require any measures to influence the laying length of the thread on the bobbin. It is known that the laying length H of the thread on the bobbin increases by reducing the traversing speed. However, this increase is so small that the reduction of the traversing speed in phase II is insignificant.

The spool change according to this invention begins in phase III with the traversing speed steadily falling to a fraction of its setpoint, i.e. the value that the traversing speed at the end of the winding travel, i.e. at the end of phase II, preferably is reduced by more than half.

Phase III is initiated by the fact that - as shown in FIG. 3 - the carriage 22 is first raised and thus turned on sufficient distance between the deflection roller 21 and the full reel 8.1 is produced. With the strong reduction in the traversing speed which now begins, the rotation of the carrier 18 takes place at the same time, so that the distance between the deflecting roller 21 and the full reel 8.1 - as shown in FIGS. 4, 5 - increases increasingly. This also increases the drag length between the deflection roller 21 and the full bobbin and thus tends to reduce the length of the thread on the bobbin. This reduction in the laying length compensates for the increase in the laying length that occurs due to the reduction in the traversing speed and is so great that the stroke shortening 2h explained with reference to FIG. 1 also occurs.

This greatly reduced traversing speed can then be maintained for a short time in phase IV. In the following phase V, the traversing speed is completely suspended. However, it is also possible, after reaching the greatly reduced value of the traversing speed, to suspend the traversing immediately without interposing phase IV. The traversing is suspended, as described above, by the thread being folded over by the auxiliary thread guide in the manner shown in FIG. 5 Phase of the bobbin change is lifted out of the traversing thread guide 3. The thread is now placed on the empty tube 7 on the winding spindle 9.2 by axial movement of the auxiliary thread guide - as explained with reference to FIG. 1.

After thread catching, a new bobbin is formed on the empty tube 7. For this purpose, the traversing speed in phase VI is used again with the last value. It should be mentioned that it is also possible to reinsert the traversing speed with a different value. If the traversing speed is reduced again starts, phase VII follows in which a base layer of no more than 10% of the total layer thickness of the coil is formed and in which the traversing speed is steadily increased again to its setpoint. Part I of the winding cycle now follows, in which the traversing speed is left at its preselected maximum value and is kept constant on average. The operating phases II, III, IV, V, VI then follow again.

This course of the traversing speed was also chosen for the diagrams and methods according to FIGS. 8 and 9. It should be noted that phase IV and phase VI, in which the traversing speed is left at its reduced value, can be omitted. Phase II can also be omitted. In this case, the traversing speed remains at the value it has in phase I until the end of the winding cycle. It is also possible, after changing the bobbin, i.e. phase V to reinstate the traversing speed with any value between the value of operating phase I and the lowest value of operating phase III.

7, 7A, the speed diagram of a method is shown in which the coil peripheral speed remains constant during the change phase.

If the circumferential speed remains constant in the course of the traversing speed, the winding speed also decreases as the traversing speed decreases. When the traversing speed ceases, the winding speed VF drops by an amount DV onto the peripheral speed VU of the spool. However, since the traversing speed has already been considerably reduced, the jump in the thread relaxation is relatively small and therefore tolerable for the winding process.

With reference to the diagrams according to FIGS. 8 and 8A, a method is described in which the circumferential speed of the spool is increased in phase III when the traversing speed is reduced and reduced in phase VII in such a way that the winding speed VF remains essentially constant. This change in the peripheral speed of the bobbin is only possible due to the large mass of the bobbin and the bobbin spindle if the reduction of the traversing speed is time-dependent, i.e. takes place steadily and slowly. It is therefore not possible that the circumferential speed of the coil is suddenly increased when the traversing is suspended. However, this is also not necessary according to the method according to the invention, since the difference DV with which the winding speed VF decreases when the traversing is suspended to the circumferentially increased peripheral speed is only very small. If e.g. the traversing speed is reduced so far before the traversing is suspended that the crossing angle is only 3 °, and if at the same time the peripheral speed has been increased to such an extent that the winding speed has remained essentially constant, as can be seen from FIG. 8A - The loss DV in winding speed at the moment the suspension is suspended is only very small, namely 1.4 per mille. This means that there is only slight thread relaxation.

In the method according to FIGS. 9 and 9A, which corresponds to that according to FIGS. 8, 8A in phases I, II, VII, the peripheral speed is increased so much during the reduction of the traversing speed in operating phase III that the winding speed VF increases. In the example shown, the peripheral speed is increased up to the value of the desired winding speed. As a result, the actual value of the winding speed increases in phases III, IV, VI, VII above its setpoint. That means but on the other hand, that during the bobbin change phase, in which the oscillation is suspended in operating phase V, the actual value of the winding speed is close to its setpoint, in the exemplary embodiment shown it is exactly at its setpoint. Even with this method, a decrease DV in the winding speed when the traversing is suspended in the operating phase V remains unavoidable. However, this decrease is not greater than in the method according to FIGS. 8, 8A and, moreover, it moves at a high thread tension level, so that thread sagging, which could lead to an interruption of the winding process, is not to be feared.

7 also shows the course of the distance A between the traversing device and the spool during the spool change phases. It should be noted in this regard that the same course also applies to the method according to FIGS. 8 and 9 and can be drawn in accordingly. The distance A is to be equated to the drag length L1 between the deflection roller 2 and the spool 8.1. It is thus the case that the deflecting roller 21 is attributable to the traversing device with regard to the filing law with which the thread is deposited on the bobbin. The thread is deposited on the spool as it is deposited on the deflection roller 21 by the traversing thread guide 3.

As previously described, the carriage 22 is raised at the beginning of phase III and the distance A between the guide roller and the spool is thus increased. This process can initially be carried out synchronously with the sharp reduction in the traversing speed taking place in phase III. However, the end of this increase in distance is after the end of phase III. Then the distance A remains constant. After the traversing speed was completely suspended in phase V and the bobbin change was carried out and the new bobbin spindle in its Operating position, the traversing speed is used again in phase VI. At the same time, however, the carriage 22 is also lowered again, thereby reducing the distance between each guide roller and the new spool again. The carriage is preferably brought back into its operating position and the deflecting roller in contact with the spool before phase VII begins to increase the traversing speed. As a result of this reduction in the distance, the traversing stroke, that is to say the depositing length of the thread on the bobbin, is increased, so that the bobbin is wound with a base layer which has a greater length than the rest of the bobbin. This reduction in the distance preferably takes place after the traversing speed has been reinstated, ie after phase V has ended.
The reduction in the distance and the simultaneous increase in the traversing speed both contribute to the formation of the conical base layer.

REFERENCE SIGN LISTING

1

Traversing device

2nd

Reverse thread shaft

3rd

Traversing thread guide

4th

Grooves

5

Straight guidance

6

thread

7

Sleeve

8th

Cheese

3.1

Full spool

9.1

Winding spindle

9.2

Winding spindle

10th

Direction of rotation

11

Auxiliary thread guide

12th

translatory direction of movement (arrow) of the winding spindle 9.1

13

Line of thread 6 on cheese 8

14

translatory direction of movement (arrow) of the winding spindle 9.2

15

translatory direction of movement (arrow) of the winding spindle

16

Direction of movement of the auxiliary thread guide

17th

Slot

18th

carrier

19th

Axis of rotation

20th

Drive roller

20.1

Drive motor

20.2

Drive motor

21

Deflection roller

22

carriage

23

Direction of movement of the slide

24th

Direction of movement of the carrier 18

25th

Direction of movement of the auxiliary thread guide

26

Thread reserve winding

Claims (12)

1. Bobbin-changing method,
   when winding a yarn (6) supplied at a constant delivery speed into a cross-wound bobbin (8) on a tube (7) which is mounted on a rotating winding spindle (9), wherein the cross-winding (2, 3) is abruptly interrupted at the end of winding travel and the yarn, for the purpose of interception at the empty tube rotating with the winding spindle, is guided in a normal plane of the empty tube and into peripheral contact with the empty tube,
   characterized in that
   shortly before or upon reaching the setpoint diameter of the bobbin (8.1) and immediately prior to the abrupt interruption of cross-winding, the cross-winding speed (VC) is reduced continuously or in small stops to such an extent that the percentage decrease in the cross-winding speed is greater than the simultaneously occurring percentage decrease in the rotational speed of the winding spindle.
2. Method according to claim 1,
   characterized in that
   with the reduction in the cross-winding speed, the peripheral speed (VU) of the full bobbin (8.1) is increased.
3. Method according to claim 3,
   characterized in that
   the peripheral speed is increased in such a manner that the wind-on speed of the yarn substantially corresponds to the setpoint value of the wind-on speed (VF).
4. Method according to claim 2,
   characterized in that
   the peripheral speed is increased to such an extent that the wind-on speed is slightly greater than the setpoint value of the wind-on speed.
5. Method according to claim 4,
   characterized in that
   the peripheral speed is increased up to the setpoint value of the wind-on speed.
6. Method according to one of the preceding claims,
   characterized in that
   the cross-winding speed is reduced to such an extent that, upon interruption of cross-winding, the wind-on speed decreases by not more than 0.5%, preferably less than 0.2%.
7. Method according to one of the preceding claims,
   characterized in that
   after interception of the yarn at the empty tube, cross-winding of the yarn is resumed substantially at the cross-winding speed at which it was interrupted, and that the cross-winding speed is then increased again continuously or in small steps up to the setpoint cross-winding speed which is required to produce the cross-wound bobbin.
8. Method according to claim 7,
   characterized in that
   the cross-winding speed is increased up to the setpoint cross-winding speed, which is required to produce the cross-wound bobbin, before 10% of the total layer thickness of the bobbin has been attained.
9. Method according to claim 7 or 8 in conjunction with one of claims 2 to 6,
   characterized in that
   upon the increase in the cross-winding speed, the bobbin peripheral speed is reduced to the extent that the wind-on speed remains substantially at its setpoint value.
10. Method according to one of the preceding claims,
    characterized in that
    the distance (A) between the full bobbin and the cross-winding device (deflection roller 21) is increased before or during the sharp reduction in the cross-winding speed, in particular is increased in such a way that the deposit length of the yarn on the full bobbin is not greater than the bobbin length of the full bobbin, in that the increase in the deposit length caused by the reduction in the cross-winding speed is compensated by the shortening of the deposit length which is caused by the increase in the distance between the full bobbin and the cross-winding device.
11. Method according to claim 10,
    characterized in that
    to increase the distance between the full bobbin and the cross-winding device, the full bobbin for initiating the bobbin change is moved continuously or progressively out of its operating position.
12. Method according to claim 10 or 11, in conjunction with claim 7 to 9,
    characterized in that
    the distance of the bobbin from the cross-winding device is reduced back to the value maintained during operation before the cross-winding speed is increased from its reduced value to its value maintained during operation.

Images