EP0453622B1 - Method and apparatus for winding yarn on a bobbin - Google Patents

Description

The invention relates to a method for winding a thread on a bobbin according to the preamble of claim 1 and an apparatus for performing the method.

A generic method and a corresponding device are known from EP-A-0 311 827. The thread guide is connected to a toothed belt which runs via a toothed wheel driven by a microprocessor-controlled stepper motor. The direct drive of the thread guide by an electric motor, which is controlled according to a program, offers great flexibility when applying bobbins, but the acceleration of the thread guide that can be applied in this way is limited to values that are quite low for important applications without additional measures. The accelerations are easily sufficient for the production of parallel windings, such as those used for the production of wire coils (DE-U-3 810 532, DE-A-2 600 511), but the associated limits lead to the production of cross-wound coils sensitive restrictions.

Additional measures supporting the reversal of the thread guide movement, such as are known, for example, from EP-A-0 311 784, are suitable, however, for nullifying the advantages of generic methods, in particular decisively restricting their flexibility. The mechanical means described there are rotatably suspended flywheels, which absorb the kinetic energy of the drive unit and, after the thread guide has passed the reversal point, return to the same. If the traversing interval changes, its position must be adjusted.

The object of the invention is therefore to provide a generic method which allows high accelerations of the thread guide at the reversal points and at the same time offers full freedom with regard to the construction of the winding and a device for carrying it out. In particular, the method should offer the possibility of producing windings according to any winding laws, such as wild windings, precision windings, step-precision windings, wild windings with image disturbance, windings with stroke breathing, conical windings etc., without any intervention in the mechanical part of the winding device can be.

The invention, as characterized in the claims, offers flexibility in the manufacture of windings that is practically only limited by the imagination of the user. In particular, a wide variety of packages, possibly with additional elements, can be produced in a very efficient manner. Common types of windings can of course be provided from the start as permanently installed programs that can be called by the user, possibly with the addition of certain parameters.

Fig. 1

eine teilweise schematische Darstellung einer erfindungsgemässen Vorrichtung zur Durchführung des erfindungsgemässen Verfahrens,

Fig. 2

einen Teil der Vorrichtung nach Fig. 1, der dort z. T. nicht sichtbar ist,

Fig. 3a

Kräfteverläufe in Abhängigkeit von der Position des Fadenführers bei der Vorrichtung gemäss Fig. 1, 2 und

Fig. 3b

den Betrag der Stromstärke in Abhängigkeit von der Position des Rotors des Elektromotors bei der Vorrichtung gemäss Fig. 1, 2, wobei untereinanderliegende Rotorpositionen und Fadenführerpositionen (Fig. 3a) einander entsprechen.

In the following, the invention will be explained on the basis of drawings representing only execution routes. Show it

Fig. 1

FIG. 2 shows a partially schematic representation of a device according to the invention for carrying out the method according to the invention,

Fig. 2

part of the device of FIG. 1, which there z. T. is not visible,

Fig. 3a

Force curves depending on the position of the thread guide in the device according to FIGS. 1, 2 and

Fig. 3b

the amount of the current intensity as a function of the position of the rotor of the electric motor in the device according to FIGS. 1, 2, rotor positions and thread guide positions (FIG. 3a) lying one below the other corresponding to one another.

A bobbin 1, on which a thread is wound, is rotatably suspended about its axis and is driven by a drive roller 2, by which it is contacted along a surface line. The thread which is wound on the bobbin 1 is guided by a thread guide 3 which, in the normal case, executes an oscillation parallel to the bobbin axis at least over a partial area of a traversing interval indicated by an arrow 4, usually about a zero point which denotes the center of the same. The thread guide 3 is fastened on a thread guide carrier 5, which is guided in a T-shaped groove 6. The movement of the thread guide 3 is brought about by a drive unit which comprises a string 7 to which the thread guide carrier 5 is fastened and which runs over deflection rollers 8a, b and a drive wheel 9 of an electric stepping motor 10. Instead of the stepper motor 10, depending on the given requirements, other types of electric motors can also be used, in particular disc-type motors with electronic commutation.

According to the invention, the stepper motor 10 is controlled by a programmable controller, which in the present case comprises a local control unit 11, which in turn is directed via data lines 12, 13 from a machine control center 14, to which a plurality of winding devices of the type described can be connected. The control unit 11 is supplied with the rotational speeds of the coil 1 and the drive roller 2, which are monitored by a tachometer, from which the instantaneous coil diameter, which must be taken into account for certain types of windings, can easily be determined. In addition, a sensor 15, which detects the passage of the thread guide 3 through a reference position, which coincides with the zero point in the middle of the traversing interval, is also connected to the control unit 11.

The basic programs for conventional windings or winding sections (wild winding, precision winding, conical windings with corresponding speed profiles, i.e. functions that determine the speed of the thread guide depending on its position, thread reserve, lower third, end turns of any shape, for example in the area of the end opposite the thread reserve Sleeve, insertion of the thread into a pair of scissors lying outside the traversing interval after completion of the winding process etc.) are stored in the control unit 11 and can be called up by the machine center 14 via the data lines 12 and 13. Parameters such as the basic stroke and the basic stroke variation for producing soft coil edges in certain winding types can be transmitted to the control unit 11. The control unit 11 calculates the paths, speeds and accelerations for the motor movement on the basis of the particular application upcoming winding laws. In the case of a stepper motor, this information is converted into pulses at certain time intervals and passed on to the power output stage that controls the motor. With a constant thread guide movement, these time intervals are constant, while they increase or decrease accordingly with deceleration and acceleration. In addition to the step pulses, logic signals for controlling the direction of rotation and the current level are also generated in the control unit 11 and fed to the motor via the output stage. The timing of the control is organized in the shortest possible successive time segments, the impulses controlling the movements of the current segment being emitted and the measurements and calculations being carried out for the following segment.

It is of course possible to transfer further programs from the machine center 14 to the control unit 11 in addition to the basic programs, so that subsequent expansion of the repertoire always remains possible.

It is generally advantageous to organize the control of the winding process so that passes of the thread guide 3 through the zero point - determined by the sensor 15 and registered by the control unit 11 - trigger sequences of control signals, after their correct execution the thread guide position again the zero point achieved, in particular a sequence of control signals can guide the thread guide from the zero point to one of the reversal points of its oscillating movement, from there to the opposite reversal point and back to the zero point. This allows the program execution to be checked and errors that have occurred, e.g. B. by additional steps if the zero point at the end of a Control sequence has not yet been reached or vice versa by prematurely aborting the control sequence, if it was reached prematurely, or to indicate if it cannot be corrected.

The device described in connection with FIG. 1 is sufficient, for example, when using suitable stepper motors available today for the production of parallel windings on flange coils or cross windings in slow winding processes such as occur in twisting, open-end or air spinning machines. At higher traversing speeds, however, the usually very abrupt reversal of the direction of movement at the reversal points requires the inertia of the moving parts of the drive unit - here the thread guide 3, the thread guide carrier 5, the string 7, the deflection rollers 8a, b, the drive wheel 9 and the Stepper motor rotor 10 - must be overcome, additional measures. As shown in FIG. 2, the drive wheel 9 is non-positively connected via gear wheels 16, 17a, b to the head ends of two torsion bars 18a, b, the opposite ends of which are fixed. Each of the torsion bars 18a, b has a sleeve 19a, b at some distance from its head end, which together with a part fastened to a magnetic coil 20a, b forms a spur tooth coupling. Each of the magnetic coils 20a, b can be actuated by the control unit 11 and causes the corresponding coupling to close and thus to shorten the effective length of the corresponding torsion bar 18a, b.

3a shows the restoring forces of the two torsion bars 18a, b as a function of the position of the thread guide 3 in the traversing interval, the dashed line denoted by a that of the torsion bar 18a, that indicated by b that of the torsion bar 18b and the solid line the sum of the two, ie represent the restoring force of the spring element formed by both torsion bars 18a, b. The equilibrium position of the latter lies in the middle of the traversing interval and coincides with the zero point.

If the thread guide 3 now moves from the zero point to the right, then the stepper motor 10 must apply an additional force which is opposite to the restoring force of the spring element and corresponds to it in order to tension the spring element. The restoring force increases linearly with a given spring constant until the thread guide 3 reaches a switchover point at which the magnetic coil 20b is activated and its spring constant is increased by shortening the effective length of the torsion bar 18b. At the same time, as shown in FIG. 3b, the current supply to the stepper motor 10 is increased to approximately three times the nominal current In, which corresponds approximately to the saturation current. Furthermore, the frequency of the control pulses directed to the stepper motor 10 is continuously reduced in such a way that its rotor experiences a constant deceleration and the thread guide 3 comes to a standstill at the reversal point. By reversing the order in which the phases of the stepping motor are energized, the rotor and thus the thread guide 3 are immediately accelerated in the opposite direction. By increasing the current and thus the motor torque and the effect of the spring element, the thread guide 3 is decelerated and accelerated very quickly in the area of the reversal point. When the return movement reaches the switchover point again, the solenoid 20b is deactivated and the clutch is released. At the same time, the power supply to the stepper motor 10 is throttled. After passing through the zero point, the process just described is repeated, with the torsion bars 18a, b etc. exchanging the rollers. To compensate for the briefly high load in the area of In the remaining area, reversal points 10 are operated with a current below the nominal current In.

As can be seen from FIG. 3a, the two torsion bars 18a, b always act in opposite directions, with the torsion bar 18a being twisted more strongly at a thread guide position to the left of the zero point, as a result of which its restoring force outweighs the torsion bar 18b to the right of the zero point. Each of the two torsion bars 18a, b, as long as the thread guide 3 is within the traversing interval, maintains a deflection - based on its equilibrium position - which does not fall below a positive minimum value. In other words, each of the two torsion bars 18a, b always remains twisted during the oscillating movement of the thread guide 3 and does not reach its equilibrium position. As a result, load changes which would result in an abrupt gripping of the gear 16 with the gear 17a or 17b are avoided and there are no dangerous shock loads on the drive unit, the spring element and the two connecting gears 16, 17a, b even at high traversing speeds.

Claims (18)

1. Method for winding a thread onto a bobbin (1), in which the thread to be wound is guided by a thread guide (3), the position of which varies over a traversing interval aligned essentially parallel to the bobbin axis and which is driven by a drive unit having an electric motor, in such a way that the position of the rotor of the electric motor varies over a limited angular range and the thread-guide position is unequivocally dependent on the rotor position and the electric motor is controlled by a programmable control as a function of a preselected winding law, characterized in that, while the thread guide (3) is located in the vicinity of a reversal point, the electric motor is operated with a current higher than the rated current (In) and, while the thread guide is located in the remaining region, the electric motor is operated with a current below the rated current (In).
2. Method according to Claim 1, characterized in that, while the thread guide (3) is located in the vicinity of the reversal point, the electric motor is operated with approximately three times the rated current (In).
3. Method according to Claim 1 or 2, in which the thread guide (3) executes essentially a movement oscillating about a zero point in the middle of the traversing interval, characterized in that passages of the thread-guide position through a reference position are recorded by the control.
4. Method according to Claim 3, characterized in that each recorded passage through the reference position triggers a sequence of control signals which, in the case of error-free execution, guides the thread guide into the reference position again, and in that, if the reference position is not reached at the end of the sequence, additional steps are included until the said reference position is reached.
5. Method according to Claim 4, characterized in that the thread guide is guided by means of each sequence of control signals, in the event of error-free execution, from the reference position to one reversal point of its oscillating movement, from there to the opposite reversal point of the latter and from there back to the reference position.
6. Method according to one of Claims 3 to 5, characterized in that the reference position coincides with the zero point.
7. Method according to one of Claims 3 to 6, characterized in that, at least during part of the movement of the thread guide (3) from the zero point towards a reversal point, additional energy originating from the drive device of the thread guide (3) is stored as result of the elastic deformation of at least one spring element and, after the reversal point is reached, is transmitted again to the said drive device.
8. Method according to Claim 7, characterized in that the additional force expended in order to generate the additional energy is an at least linearly rising function of the deflection of the thread guide (3).
9. Method according to Claim 8, characterized in that the additional force is a function of the thread-guide deflection which is at least approximately linear in each case between the zero point and a change-over point and between the change-over point and the reversal point and the gradient of which is higher in the second region than in the first.
10. Method according to one of Claims 7 to 9, characterized in that the additional force is a function of the thread-guide position which is anti-symmetric about the zero point.
11. Method according to Claim 9 or 10, characterized in that the change-over points coincide essentially with the inner limits of the region of the thread-guide position in which the electric motor is operated with a higher current than the rated current (In).
12. Method according to one of Claims 1 to 11, characterized in that the control of the electric motor also takes into account parameters which are dependent on the state of the bobbin.
13. Method according to Claim 12, characterized in that the control takes into account the respective bobbin diameter.
14. Apparatus for carrying out the method according to one of Claims 1 to 13, with a thread guide (3), the position of which is variable over a traversing interval, and with a drive unit having an electric motor, to which the thread guide is connected in such a way that its position is unequivocally dependent on the rotor position of the electric motor, and a programmable control for the drive unit, characterized in that the control is designed in such a way that, while the thread guide (3) is located in the vicinity of a reversal point, the electric motor is operated with a higher current than the rated current (In) and, while the thread guide (3) is located in the remaining region, the electric motor is operated with a current below the rated current (In), and moreover, for building up a restoring force pointing towards the zero point of the thread-guide movement, the apparatus has at least one spring element which is connected non-positively to the drive unit and which is provided with an electrically actuable coupling, by means of which its effective length can be reduced for the purpose of increasing the spring constant in a region which consists of two intervals limited in each case by a reversal point and a change-over point located between the latter and the zero point.
15. Apparatus according to Claim 14, characterized in that the at least one spring element is a torsion bar (18a, 18b).
16. Apparatus according to Claim 14 or 15, characterized in that it contains at least one pair of oppositely acting spring elements, the deflections of which, in relation to the respective position of equilibrium, in each case do not fall below a positive minimum value, as long as the thread guide (3) is located within the traversing interval.
17. Apparatus according to one of Claims 14 to 16, characterized in that the electric motor is a stepping motor (10).
18. Apparatus according to one of Claims 14 to 16, characterized in that the electric motor is a disc-armature motor with electronic commutation.

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