EP0194524B1 - Winding method - Google Patents

Description

The invention relates to a winding process for threads, in particular chemical threads in spinning and stretching machines. Chemical threads are threads made of thermoplastic materials. The industry uses in particular polyester (polyethylene terephthalate) and polyamide (nylon 6, nylon 6.6). Chemical threads consist of a large number of individual capillaries and are therefore referred to as multifilaments.

Such multifilament chemical threads offer the problem of mirror formation when spooling if they are spooled in a wild winding.

In the case of the wild winding, the coils are formed at a constant coil circumferential speed and at a constant traversing speed. The result of this is that the winding ratio - that is the ratio of the speed of the winding spindle to the double stroke number of the traversing (ns / DH) - decreases steadily over the course of the winding cycle, since the speed of the winding spindle! decreases with increasing coil diameter. Mirrors are created when the winding ratio becomes an integer or takes values. that differ by a large fraction from the next integer winding ratio. A "large fraction" is a fraction whose denominator is a small whole number (integer), e.g. 1/2, 1/3, 1/4.

DE-OS 2 319 282 discloses a method for disturbing the mirror, in which a change with a low frequency and also a change with a high frequency are superimposed on the setpoint value of the traversing speed. This is to avoid the formation of mirrors.

In the case of a precision winding, the coil is built up at a traversing speed that is directly proportional to the speed of the winding spindle. This means that with a precision winding the winding ratio - that is the ratio of the speed of the winding spindle to the double stroke rate of the traversing speed - is fixed and remains constant during the winding cycle, while the traversing speed decreases proportionally to the spindle speed with the winding ratio as a proportionality factor. A coil built in precision winding can have advantages over a coil built in wild winding. In particular, mirror formation can be avoided in the case of a precision winding by specifying the winding ratio.

The so-called graduated precision winding differs from the precision winding in that the winding ratio remains constant only during predetermined phases of the winding cycle. From phase to phase, the winding ratio in jumps is reduced by suddenly increasing the traversing speed.

This means that with the stepped precision winding, a precision winding takes place within each phase or step, in which the traversing speed decreases proportionally with the spindle speed. After each phase, the traversing speed is increased again suddenly, so that there is a reduced winding ratio. The winding conditions that are to be maintained during the individual phases must be calculated in advance and programmed.

In the winding method with step-precision winding known from DE-AS 26 49 780, only a few winding ratios are specified as integer ratios within a winding trip and are set by a computer by entering the thread spacing. This is only possible because the thread tension is regulated at the same time. Where this is not the case, however, the changes in the traversing speed may only be chosen so small that the thread tension remains within certain limits.

Such a method is known from EP-A 0 055 849. An upper limit value and a lower limit value are specified for the traversing speed, and only changes in the traversing speed between these limit values are permitted. The range between these limit values is so narrow that the change in the traversing speed does not lead to impermissible thread tension changes. Nevertheless, it must be avoided that winding conditions are set with mirror symptoms. The precalculation of the winder ratios to be set one after the other must therefore be carried out with great care and accuracy, and in cases of doubt, tests must also be carried out to determine whether a predicted winder ratio actually does not lead to game game symptoms in practice.

It has now been found that the winding ratios that are to be set one after the other can be calculated with great accuracy so that a good precision winding should theoretically arise, but that nevertheless thick beads in a diamond-shaped arrangement were formed from time to time on the surface of the spool. It was not possible to avoid this phenomenon by calculating the winding conditions more precisely.

It has now been found that in order to achieve optimal thread placement, the bobbin ratios not only have to be precalculated with great accuracy, but also have to be adhered to exactly, and that here the electrical and electronic measuring and control technology required for measuring the speeds and for complying with Proportionality between spindle speed and traversing speed is responsible, at least reaches its economic limits.

In particular, the use of a synchronous motor to drive the traversing device would be required to achieve sufficient accuracy.

The object of the invention is to make the step precision winding method a suitable method for producing high-quality coils with a large diameter, even if the technical accuracy of the electronic, electrical and mechanical devices does not allow the spool ratios to be kept exactly as before have been determined and programmed as optimal.

The solution according to the invention is characterized in that an inaccuracy of the winding ratio is deliberately brought about. The invention makes use of the knowledge that the unintentional inaccuracy is constant and always has the same phase direction to the exact value, so that the defects in the thread deposit caused by the inaccuracy of the winding ratio are constant in terms of size and phase direction. The drive of the traversing device is e.g. run faster than specified by the program. However, it will not fluctuate at times faster and at times slower than specified by the program. The inaccuracy, which is intended according to the invention but fluctuates, deliberately causes defects in the thread deposit, which however also fluctuate in size and phase direction. This not only eliminates the consequences of these defects, but also completely eliminates the defects in the thread deposit.

The modulation of the winding ratio proposed according to the invention has a modulation width A which is so small that the traversing speed does not change by more than ± 0.5% of the calculated and programmed value of the traversing speed. This means that the modulation width of the winding ratio is generally less than 0.1%, but preferably less than 1 per mille and generally also less than 0.5 per mille. It has been found that the modulation width, based on the winding ratio, is substantially equal to the modulation width, based on the traversing speed.

In the context of this application, the modulation range is given by the formula A = (KO - KU) x 2 / KO + KU = 2 (KO - KM) / KM = 2 (KM - KU) / KM where K is the winding ratio KM is the average winding ratio during the phase of a precision winding KO the upper limit of the winding ratio KU is the lower limit of the winding ratio.

Modulation widths of more than 0.5% must be avoided in any case, since otherwise it is no longer guaranteed that critical winding conditions will not be run through. Critical winding ratios are those in which the mirror symptoms described above occur.

The modulation is preferably fluctuating periodically. The frequency of the fluctuations must be greater than 5 per minute, preferably greater than 10 per minute. Experience has shown that at frequencies of the fluctuation of more than 30 per minute, all winding errors which have been described above can be eliminated.

The modulation can be limited to those sections of the winding cycle in which experience has shown that problems with winding, in particular bead formation, occur. However, the modulation can also take place as a function of disturbances which appear on the take-up device. It should be pointed out here that bead formation leads to vibrations of the winding device and also to noise. As soon as such disturbances in the take-up device are detected, these disturbances can be detected by sensors and the output signal of the sensors can be used to switch on the modulation. In a further embodiment of the invention it is provided that a constant scanning, preferably optical or pneumatic scanning of the coil surface takes place and that the modulation is switched on when bulges appear on the coil surface.

It has now been found through tests that, depending on the spinning parameters, in particular titer, traversing speed, bobbin length and overall bobbin thickness, it may be expedient to increase the modulation width of the bobbin ratio in the course of the winding cycle. As a result, the quality of the thread deposit can be further improved.

An embodiment of the invention is described below.

• Fig. 1A stellt einen vergrößerten Ausschnitt von Fig. 1 dar.
• Fig. 2 zeigt ein typisches Changierdiagramm für eine Stufenpräzisionswicklung mit dem Spulendurchmesser D als Abszisse und der Changiergeschwindigkeit VC als Koordinate. Gezeigt ist, daß auf einer Hülse von 100 mm Durchmesser eine Spule aus einem Faden aufgewickelt wird mit einem Enddurchmesser von 450 mm. Die Schwankungen, die nach dieser Erfindung der Changiergeschwindigkeit aufgeprägt werden, sind so gering, daß sie in Fig. 2 nicht dargestellt werden können.
• Fig. 3 zeigt den Querschnitt durch eine Aufwickelmaschine für Chemiefasern, wobei insbesondere die Steuereinrichtungen gezeigt sind.

In Fig. 1 the course of the winding ratio is shown during this coil construction of 100 to 450 mm in diameter.

• 1A shows an enlarged section of FIG. 1.
• 2 shows a typical traversing diagram for a step precision winding with the coil diameter D as the abscissa and the traversing speed VC as the coordinate. It is shown that a bobbin is wound from a thread with a final diameter of 450 mm on a sleeve of 100 mm in diameter. The fluctuations which are imposed on the traversing speed according to this invention are so small that they cannot be shown in FIG. 2.
• Fig. 3 shows the cross section through a winding machine for man-made fibers, in particular the control devices are shown.

The winding machine is first described with reference to FIG. 3.

The thread 1 runs at the constant speed v through the traversing thread guide 3, which is set in a reciprocating movement transversely to the running direction of the thread by the reverse thread shaft 2. In addition to the thread guide 3, the traversing device includes the grooved roller 4, in the endless, back and forth groove of which the thread is guided with a partial wrap. 7 with the coil and 6 with the freely rotatable winding spindle (spindle) is designated. The drive roller 8, which is driven at a constant peripheral speed, lies against the circumference of the coil 7. It should be mentioned that the driving roller and traverse on the one hand and the winding spindle and the spool on the other hand are radially movable relative to one another, so that the center distance between the spindle 6 and the driving roller 8 can be changed as the diameter of the spool increases. The reverse thread roller 2 and the grooved roller 4 are driven by a three-phase motor, for example an asynchronous motor 9. The reverse thread roller 2 and Grooved roller 4 are connected to one another in a geared manner, for example by drive belts 10. The drive roller 8 is driven by a synchronous motor 11 at a constant peripheral speed. It should be mentioned that a motor can also be used to drive the bobbin, which drives the bobbin spindle 6 directly and whose speed is controlled so that the peripheral speed. the coil remains constant even with increasing coil diameter. The three-phase motors 9 and 11 receive their energy from frequency converters 12 and 13. The synchronous motor 11, which serves as a coil drive, is connected to the frequency converter 12, which supplies the adjustable frequency f2. The asynchronous motor 9 is operated by frequency converter 12, which is connected to a computer 15. The output signal 20 of the computer 15 depends on the input.

The following are continuously entered: the speed of the winding spindle 6, which is determined by sensor 18; the output signal of the program unit 19 connected upstream of the computer, which is preferably freely programmable and in which the winding ratios have been entered, which are to be moved in succession in the individual phases with precision winding in the course of the winding cycle.

The current traversing speed or double stroke number is also advantageously sensed by sensor 17 and input to the computer by sensor 17. The computer 15 carries out a target / actual value comparison and regulates the traversing speed of the traversing devices driven by the asynchronous motor 9 to the target value. The setpoint value of the traversing speed is the value which results from the rotational speed of the winding spindle 6, currently measured by measuring sensor 18, divided by the winding ratio, which is pre-calculated for the respective winding phase and entered into the computer 15 by the program unit 19.

The main task of the computer 15 is to carry out this setpoint determination of the traversing speed.

For this purpose, the computer first receives from the program memory or program generator 19 the pre-calculated winding conditions which are ideal and stored in the sense of the invention. From each of these ideal winding conditions and from the initial value, e.g. The computer calculates an "ideal" spindle speed based on the upper limit value (OGC) of the traversing speed. However, the programmer can also be entered the spindle speeds previously calculated from the "ideal" winding conditions, taking into account the initial value of the traversing speed, so that this computing operation does not have to be carried out by the computer. In any case, the values of the "ideal" spindle speeds are compared with the current spindle speeds determined by the sensor 18. If the computer determines the identity of the spindle speeds, it outputs the output value 20 of the traversing speed, which is also predetermined by the programmer 19, as the setpoint to the frequency converter 13. In the following course of the winding cycle, the computer reduces this setpoint value of the traversing speed in proportion to the constantly measured spindle speed, which decreases hyperbolically with increasing coil diameter and constant coil peripheral speed. The predetermined "ideal" winding ratio thus remains constant during this stage of the precision winding. As soon as the computer now determines that the currently measured spindle speed is approaching the "ideal" spindle speed determined by the next winding ratio specified as "ideal", the output value of the traversing speed is again specified as the setpoint as output signal 20. A new level of precision winding follows.

Since the speed of delivery of the thread to the bobbin is constant (e.g. spinning a chemical thread) and for this reason the surface speed of the bobbin must remain constant despite the increasing diameter, the speed of the winding spindle decreases hyperbolically in the course of the winding cycle. It is now also necessary that the thread tension of the thread on the bobbin remains within certain limits in order to bring about a proper bobbin build-up. For this reason, the traversing speed must remain within predefined, narrow limits OGC and UGC. A specific ideal winding ratio K is constantly specified and programmed in each phase P of the winding cycle or the diameter structure. A constant winding ratio K during a winding phase P means that the traversing speed decreases in proportion to the spindle speed. This decrease in the traversing speed can only be permitted until the lower limit value UGC of the traversing speed is at least approximately reached. In the diagram according to FIGS. 1 and 1A, this means that the upper limit value OGK of the winding ratio has been reached. Now the traversing speed must be increased suddenly to its upper limit OGC. This abrupt increase in the traversing speed in FIG. 1, FIG. 1A means an abrupt decrease in the winding ratio K to its lower limit value UGK.

It follows from this that in the described embodiment the upper limit of the traversing speed is a constant value which is continuously reset in the course of the winding cycle. It is always set when this variable assumes a pre-calculated, ideal value in relation to the current spindle speed. The lower limit value of the traversing speed, on the other hand, is only a mathematical quantity that indicates the greatest permissible drop in the traversing speed, which, however, is rarely or never achieved in reality and only plays a role in the calculation of the upper limit value. It should be noted that the process can also be controlled in reverse. The lower limit value of the traversing speed can be specified as a real limit value that is repeatedly approached. The upper limit then indicates the largest permissible jump in the traversing speed upwards. However, in reality it only becomes exceptional If the upper limit value happens to have an ideal predicted value in relation to the current spindle speed.

As mentioned, the thread tension may only fluctuate within certain limits, so that the range between the limit values of the traversing speed OGC and UGC is very narrow. This also means that two winding ratios K1 and K2 of the two successive winding phases P1 and P2 must be relatively close together. Nevertheless, the successive winding conditions must be selected so that there is no risk of mirror formation. As a result, the number of favorable winding ratios available for selection is relatively limited and it cannot be avoided that a favorable winding ratio for K1 is very close to another unfavorable winding ratio which leads to bead formation. So it was e.g. required to select a winding ratio of 4.08631 for K1, which results in a good winding build-up if exactly adhered to. This good winding structure was actually achieved when the winding ratio was adjusted in laboratory operation. In practical operation, however, it turned out that despite the correct prediction of the winding ratio, a very strong bead formation was shown. Measurements from spindle speed and traversing speed showed that the winding ratio was actually 4.08696. Despite this extremely small deviation of only 0.015%, there was therefore a very poor package build-up, caused by the deviation of the actual winding ratio from the winding ratio which was calculated and set well in advance. According to the invention, the first-mentioned winding ratio = 4.08631 was again set without increasing the accuracy requirements for the measurement data acquisition and the adjustment and control of the traversing speed, and this setpoint was also modulated in a theoretical sine line. For this purpose, the associated setpoint of the traversing speed was changed sinusoidally by ± 0.005% at a modulation frequency of 20 per minute.

This electronically and electrically simple measure made it possible to completely eliminate the formation of bulges and to achieve a perfect winding structure. It was shown that the coil structure became better with increasing modulation frequency.

1A shows the sinusoidal modulation of the winding ratio with the modulation amplitude (modulation width) A and a certain modulation frequency.

In the course of the winding cycle, in which winding ratios between 7.1227 and 1.3599 were passed through, the value of the modulation width was increased uniformly by 0.1 per mille of the respective winding ratio each time the winding ratio was lowered, and a good bobbin build-up was thereby achieved.

In order to achieve this modulation of the traversing speed, a program for sinusoidal modulation of the traversing speed is further input to the program unit 19. This program can be a constant or variable, e.g. Provide increasing modulation amplitude (modulation width) during the winding cycle. The modulation range according to this invention is in any case less than 0.5%, preferably less than 0.1%. It should be emphasized that the modulation amplitude should be chosen as narrow as possible, since this has improved the quality of the coil. It must be taken into account how close the spool ratios must be to each other in order to avoid impermissible thread tension changes, but still maintain a good spool build-up. The smaller the difference between the spool ratios, the smaller the modulation width. In general, the modulation width with which the traversing speed is changed is less than 1 per mille.

Claims (7)

1. Process for winding yams, in particular freshly spun or drawn man-made filament yarns, into cylindrical cross-wound packages in stepwise precision winding, where, in every step of the precision wind, the traverse speed is reduced proportionally to the spindle speed and then, to obtain a predetermined lower package ratio (number of spindle revo- lutions/number of double traverses), increased again sharply, characterized in that the traverse speed is predetermined in the form of its average value and constantly recurring deviations are allowed as long as these deviations A amount to less than 0.5% and reoccur constantly at a frequency of more than 5 per minute.

2. Process according to Claim 1, characterized in that the modulation width A of the spool ratio is not more than 0.1 %.

3. Process according to Claim 1, characterized in that the modulation width A of the package ratio is less than 0.2 per thousand.

4. Process according to Claims 1, 2 or 3, characterized in that the modulation frequency is greater than 10 per minute, preferably greater than 30 per minute.

5. Process according to any one of Claims 1 to 4, characterized in that the modulation takes place as a function of disturbances, for example vibrations or noises, emanating from the winding means.

6. Process according to any one of Claims 1 to 4, characterized in that the modulation is effected as a function of the structure of the package surface by scanning the package surface.

7. Process according to any one of Claims 1 to 6, characterized in that the modulation width is increased in the course of the package build-up.

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