EP0512257B1 - Procedure and device for controlling the rotational speed of spindles of a twisting machine - Google Patents

Description

The invention relates to a method according to the preamble of claim 1

It is known (DE-AS 12 73 389) to reduce the spindle speed with increasing, average wind-up diameter during a draw in a draw twisting machine. The course of the spindle speed changes is stored in a control program that is run during the withdrawal. To determine the control program, the thread tension is measured during a take-off, the spindle speed program thus being determined empirically.

It is also known (DE-AS 16 60 339) to reduce the thread tension in the area of the reversal points in such a spindle speed control program with each ring bank stroke by reducing the spindle speed in these areas. Thereby Fluctuations in the elastic modulus of the thread should be avoided.

The invention has for its object to obtain the most correct, uniform bobbin construction by maintaining a thread tension as constant as possible.

This object is achieved by the characterizing part of claim 1.

This design takes into account the fact that thread balloons are present between the delivery device and the runners rotating on rings, the axial length of which varies depending on the position of the ring bench relative to the delivery device. The axial length of these thread balloons has a considerable influence on the thread tension, which becomes smaller as the axial length of the thread balloons becomes smaller and larger as the axial length increases. By compensating or at least smoothing the thread tension fluctuations caused thereby, a significant improvement in the bobbin construction can be obtained. With each ring bench stroke, the spindle speed is therefore corrected in accordance with this change in thread tension.

An advantageous application of the invention also results in methods and devices in which the endless filaments are "swirled" immediately before being wound up by means of a ring and a runner. In these methods and devices, the filament threads are passed through nozzles in which they are exposed to the influence of compressed air jets in such a way that the individual capillaries are entwined with themselves and / or with other capillaries. As a result of this intermingling, the cohesion of the filaments and thus the coherence of the thread becomes increased, some achieved a different type of thread character. The intermingling achieved depends essentially on the tension under which the filaments stand during the intermingling. In order to achieve a uniform interlacing effect, the thread tension in the interlacing zone should therefore be as uniform as possible. This condition can be met to a large extent with the invention. As such, it would be possible to carry out the intermingling in a further field following the last stretching field with high-speed godets and laying rollers, in which the thread tension can be kept relatively constant. For reasons of economy, however, the aim is to dispense with such a further field and to carry out the intermingling in the twisting or winding zone. In this case, the invention can then be used with advantage.

In an embodiment of the invention it is provided that the thread tension in the continuous filament yarn supplied to the bobbin is detected at at least one working position, and that a spindle speed control is carried out to keep the thread tension constant.

In another embodiment of the invention, it is provided that the increasing winding diameter of the coils and the height position of the ring rail is detected and that a predetermined spindle speed setpoint is controlled as a function thereof becomes. This configuration has the advantage that it requires less technical effort.

Fig. 1

zeigt eine schematische Darstellung einer Arbeitsposition einer Streckzwirnmaschine mit Mitteln zum Erfassen der Fadenspannung, aufgrund deren Auswertung eine Spindeldrehzahlkorrektur vorgenommen wird,

Fig. 2

eine schematische Darstellung einer Arbeitsposition einer Streckzwirnmaschine mit Mitteln zum Erfassen der Höhenposition der Ringbank, wobei die Höhenpositionsignale ausgewertet werden, um die mit einem Spindeldrehzahlsteuerprogramm vorgegebene Spindeldrehzahl zu korrigieren,

Fig. 4

ein Diagramm zur Darstellung des Verlaufs des Ringbankhubes während des Aufbaus einer Spule mit Kötzerwicklung,

Fig. 5

ein Diagramm zur Darstellung des Verlaufs des Ringbankhubes während des Spulenaufbaus einer Spule mit Kombiwicklung,

Fig. 6

ein Diagramm zur Darstellung des Verlaufs des Ringbankhubes während des Spulenaufbaus einer Spule mit Verbundwicklung,

Fig. 7

ein Diagramm zur Darstellung des Verlaufs einer Spindeldrehzahlkorrektur in Abhängigkeit von dem Abstand zwischen einem Fadenführer und einer Ringbank und damit von der axialen Länge eines sich zwischen dem Fadenführer und der Ringbank ausbildenden Fadenballons,

Fig. 8a bis c

Diagramme ähnlich Fig. 7 und deren Änderung während des Abzugs entsprechend einem Spindeldrehzahlprogramm,

Fig. 9

ein Diagramm zur Erläuterung der Korrektur der Spindeldrehzahl bei einem Wickeln im Bereich der Böschungen der erzeugten Spule ohne Berücksichtigung der Korrektur zum Ausgleich der Spannungsschwankungen aufgrund eines sich ändernden Fadenballons,

Fig. 10

ein Diagramm ähnlich Fig. 9 mit fortschreitendem Spindeldrehzahlprogramm während des Abzugs,

Fig. 11a und 11b

Diagramme zur Darstellung der überlagerten Korrekturwerte zum Ausgleichen der Fadenspannung aufgrund sich ändernder axialer Länge des Fadenballons und aufgrund eines Wickelns in den Böschungsbereichen,

Fig. 12

ein Diagramm zur Erläuterung der Korrektur der durch ein Spindeldrehzahlprogramm vorgegebenen Grunddrehzahl der Spindel während der Ringbankhübe zum Ausgleich von durch die axiale Länge eines Fadenballons verursachten Fadenspannungsschwankungen und

Fig. 13

eine Einzelheit der Fig. 12 in vergrößertem Maßstab mit Korrektur der Spindeldrehzahl aufgrund eines Aufwindens im Bereich der oberen Böschung und der unteren Böschung einer Spule.

Further features and advantages of the invention result from the following description of the embodiments shown in the drawing and the subclaims.

Fig. 1

1 shows a schematic representation of a working position of a draw twisting machine with means for detecting the thread tension, based on the evaluation of which a spindle speed correction is carried out,

Fig. 2

1 shows a schematic representation of a working position of a draw twisting machine with means for detecting the height position of the ring bench, the height position signals being evaluated in order to correct the spindle speed specified with a spindle speed control program,

Fig. 4

a diagram showing the course of the ring bench stroke while building a coil with Kötzerwickung,

Fig. 5

1 shows a diagram to show the course of the ring bench stroke during the build-up of a coil with a combination winding,

Fig. 6

1 shows a diagram to show the course of the ring bench stroke during the build-up of a coil with a composite winding,

Fig. 7

2 shows a diagram to show the course of a spindle speed correction as a function of the distance between a thread guide and a ring bench and thus of the axial length of a thread balloon forming between the thread guide and the ring bench,

8a to c

7 and diagrams similar to FIG. 7 and their change during the withdrawal in accordance with a spindle speed program,

Fig. 9

1 shows a diagram for explaining the correction of the spindle speed when winding in the area of the slopes of the generated coil without taking into account the correction to compensate for the voltage fluctuations due to a changing thread balloon,

Fig. 10

9 shows a diagram similar to FIG. 9 with a progressing spindle speed program during the withdrawal,

11a and 11b

Diagrams to show the superimposed correction values for compensating the thread tension due to the changing axial length of the thread balloon and due to winding in the embankment areas,

Fig. 12

a diagram for explaining the correction of the basic speed of the spindle specified by a spindle speed program during the ring bench strokes to compensate for thread tension fluctuations caused by the axial length of a thread balloon and

Fig. 13

a detail of FIG. 12 on an enlarged scale with correction of the spindle speed due to a winding in the area of the upper slope and the lower slope of a coil.

1 shows part of a working position of a draw twisting machine which has a plurality of such working positions on at least one machine side. An endless filament yarn (10) is fed to a spool (14) via a godet (11) provided with a laying roll and a stationary thread guide (12) via a rotor (13). The rotor (13) runs on a ring (15) of a ring bench (16) which is driven in a manner not shown for lifting movements. The lifting movements of the ring bench (16) determine the shape of the coil (14), which will be explained in more detail later with reference to FIGS. 3 to 6. The coil (14) is attached to a spindle (17) which is driven to rotate. For the sake of simplicity it is assumed that each spindle (17) is assigned its own drive motor, the speed of which can be varied. Of course, it is also possible to provide a common drive motor for all spindles of at least one machine side, the speed of which can then be changed accordingly.

The spindles (17) are assigned a spindle drive system (18) which is only indicated schematically and which contains, for example, a frequency converter for changing the spindle speed. A control and regulating system (19) is assigned to the spindle drive system (18) and specifies the speed to be observed in each case. A spindle speed program is stored in the computer system (19), that is moved during a trigger, ie from the beginning of the winding to the end of the winding of the coil (14). According to this spindle speed program, the spindle speed is gradually reduced during the withdrawal, the course of the spindle speed being determined empirically or mathematically.

In the embodiment according to FIG. 1, the spindle speed is corrected or varied in accordance with the measured thread tension. For this purpose, the thread tension is measured while the machine is running according to the lowest godet (11) by means of a transducer (20) which supplies a signal proportional to the thread tension. This signal is fed to a transducer (21) which delivers a signal which can be processed there to the computer system (19). As indicated by arrows (22), the thread tension is expediently measured by means of several sensors (20) at several working positions, e.g. in five to six working positions. An average value is formed from these measured values so that any short-term fluctuations that can occur as a result of external disturbances are eliminated. The mean value from the thread tension measurements is compared in the computer system (19) with a predetermined target value and its entered tolerance window. If deviations are found, the setpoint of the spindle speed is readjusted and given to the spindle drive system (18). The method used in the embodiment according to FIG. 1 can be implemented for all types of windings that are suitable for the construction of the coil (14). In the simplest form, a spindle speed program can also be dispensed with. In most cases, however, it will be expedient to superimpose the speed variations on a basic speed specified by a control program.

In the illustration according to FIG. 1, the sensor (s) (20) attack the continuous filament yarn (10) in the area between the godet (11) and the thread guide (12). In a modified embodiment, the transducers (20) aimed directly at the balloon between the thread guide (12) and the runner (13). Of course, other arrangements of transducers can also be used.

2 shows a working position of a draw twisting machine corresponding in its construction to the embodiment according to FIG. 1. The spindles (17) are controlled by a spindle drive system (18), to which a computer system (19) is assigned. A spindle speed program is stored in the computer system (19) and is run during the build-up of the coil, the spindle speed being reduced as the winding diameter of the coils (14) increases. The ring bank (16) is assigned an encoder (23) which is designed as an incremental encoder or absolute encoder and which measures the current ring bank position. The spindle speed setpoint is changed in the computer system (19) in accordance with the measured position of the ring rail and specified for the spindle drive system (18). The position of the ring bench (16) and the direction of movement of the ring bench (16) are determined incrementally, analogously or absolutely. The determined value is evaluated in the digital computer system (19), which specifies a corresponding target value for a speed controller of the spindle drive system.

Instead of delivery devices in the form of a godet (11), other delivery devices can of course also be provided, for example also delivery spools from which the continuous filament is unwound.

4 to 6 show the most common forms of winding for bobbins (14) which are produced in draw twisting machines. Of course, other forms of winding are also possible, for which the invention is also suitable.

In Fig. 4 the course of the lifting movement of the ring rail is shown schematically, with which a Kötzerwickel is generated. The stroke of the ring bench (H) remains essentially the same throughout the coil build-up. It begins at the lower reversal point and is then steadily raised in level, so that an upper embankment area (B₁) and a lower embankment area (B₂) arise. With this type of winding, the ring rail moves into the upper embankment area (B 1), in which case the wind diameter is reduced due to the embankment. Deviations from this construction are possible, the lifting height being varied during the construction of the coil.

5 shows the structure of a so-called combination winding. With this type of winding, the lower reversal point of the ring rail is moved upwards during the construction of the cop, so that a lower slope (B₂) is generated. In addition, the stroke (H) of the ring rail (16) is varied during the build-up of the coil, so that an upper embankment area (B 1) is also produced, which is operated by the ring rail (6).

In Fig. 6 the principle of a composite winding is shown, in which the ring bank carries out a lifting movement of the same size during the entire coil build-up, but the upper and lower reversal point are periodically shifted up and down again, so that here too an upper slope (B₁) and a lower slope (B₂) with a central, substantially cylindrical section. The ring bench (16) also moves in the area of the lower embankment (B₂).

As shown in Fig. 7, the spindle speed program specifies a basic speed (n _g ) which is based on the wind-up diameter the coil (14) is dependent on the relevant time of the coil construction. The influence of the thread balloons formed between the thread guide (12) and the rotor (13) on the thread tension has not yet been taken into account in this basic speed (n _g ). This influence is taken into account by means of the device shown in FIG. 1 or FIG. 2 by varying the basic speed (n _g ) in order to keep the thread tension constant (taking into account an allowable tolerance). 7 is based on the fact that the device according to FIG. 2 is used. In addition to the spindle speed program which defines the basic speed (n _g ), a variation value in the form of a curve (25) is defined in the computer system (19), on the basis of which the basic speed (n _g ) is varied in accordance with the height position of the spindle bank (16), so that the spindle speed (n _s ) is controlled. In general, the curve (25) is defined so that with a reduction in the axial length of the thread balloon, ie the axial distance between the delivery device (godet 11) and rotor (13), the spindle speed (n) is increased and vice versa in order to keep the thread tension constant . As indicated in Fig. 7, the curve (25) of the variation values need not have a linear course. It can have a concave shape (25 ') or a convex shape (25''). This depends on the one hand on the material of the continuous filament yarn and on the other hand above all on the type and speed of the lifting movement of the ring rail (16). In particular, if special acceleration controls are provided for the lifting movement of the ring bench (16), there are deviations from a linear course.

As shown in Fig. 8a, the variation curves (25) can form a parallel family of curves in the course of the coil build-up, ie with increasing wind diameter and thus reduced basic speed (n _g ). However, it is also possible, as shown in FIGS. 8b and 8c, to make variations in the manner during the coil construction that there are no parallel families of curves.

In the case of coil forms in which windings occur again and again in the area of the upper embankment (B₁) or the lower embankment (B₂) during the entire coil build-up, ie in the case of winding forms corresponding to FIGS. 4, 5 and 6, the winding takes place in the area of the embankments ( B₁, B₂) with a reduced wind diameter. In order to maintain a constant thread tension in the area of the embankments (B₁, B₂), according to the invention, the spindle speed is increased compared to the basic speed (n _g ) specified by the spindle speed program when winding in this area. It is necessary in the area of the upper embankment (B₁) to increase the speed more than in the area of the lower embankment (B₂), since here the influence of the correspondingly enlarged or reduced thread balloon is added.

If only the influence of the decreasing wind diameter in the embankments (B₁, B₂) is to be taken into account, which is entirely within the scope of the present invention, then a family of curves according to FIG. 10 results from the course of the basic speed determined by the spindle speed program Coil build-up or time (T). The spindle speed control program defines constant basic speeds for the central, cylindrical region of the coil (14) between the embankments (B 1, B 2). In the area of the embankments (B₁, B₂), correction programs also stored in the computer system then determine that when entering the embankment areas (B₁, B₂) a corresponding speed increase and a corresponding speed reduction take place after reaching the upper or lower reversal point, until again the basic speed (n _g ) assigned to the winding diameter of the central region of the coil (14) has been reached.

Appropriately, however, there is both a variation to compensate for the axial length of the thread balloon (distance between delivery device (11) and rotor (13)) and to compensate for the influence of changes in the embankment areas (B₁, B₂) Wind diameter. This variation in base speed (n _g ), which is determined by the spindle speed control program, is shown in FIGS. 11a and 11b. Here, too, these curves are additionally stored in the computer system, the variation values being predetermined by the transducer (23) of FIG. 3, which detects the height position of the ring bank (16). 11a shows a superimposition of the measures explained with reference to FIGS. 7 and 9. In the central, cylindrical region of the bobbin, the basic speed (n _g ), which is specified by the spindle speed control program for the winding diameter there, is varied in accordance with the axial length of the thread balloon. In the upper and lower embankment areas (B₁, B₂) there is an additional variation by increasing the spindle speeds in order to take into account the smaller wind diameters in the area of the embankments (B₁, B₂).

As shown in FIG. 11b, the course of the curve according to FIG. 11a can also be approximated by a curve composed of only two linear sections. The specified tolerance fields are then not left. In addition, it is also possible to store other curve shapes for the variation values in the computer system, for example convex or concave curved shapes. As already mentioned, the curve shape depends on the material to be processed and in particular also on the type of drive of the ring bench (16), i.e. after the course of the ring bench speed, for example accelerations before the reversal points or acceleration over the entire stroke.

The diagram of FIG. 12 shows the course of the spindle speed (n) over the coil structure, ie over time (T). The spindle speed control program defines basic speeds (n _g1 , n _g2 .... n _gn ) with which the speed is gradually reduced over time, the steps being 50 min⁻¹, for example. This basic speed (n _g ) depends on the directly measured thread tension or the height position of the Ring bank (16) changed by the variation value (Δn) during each stroke of the ring bank (16). It should be mentioned once again that these variations are shown in a highly schematic manner and that in reality the stroke-dependent speed curve can deviate significantly from a linear straight line. A non-constant ring bench speed, for example with acceleration before the turning points and / or acceleration over the entire stroke, can already lead to deviations.

As shown in Fig. 13 on a larger scale, in addition to the spindle speed variation depending on the height position of the ring bank (16), a spindle speed variation in the embankment areas (B₁, B₂) by a combination there in order to keep the thread tension as constant as possible both variation measures is carried out. As can be seen from Fig. 13, from time (t 1), which represents the beginning of the upper slope area (B 1), the spindle speed is increased more than in the cylindrical area. From the time (t₂), which represents the reversal point of the ring bank above, the spindle speed is reduced again until it reaches the end of the upper slope area (B₁) at time (t₃). From time (t₄), i.e. the beginning of the lower embankment area (B₂), the spindle speed is not reduced further, but slightly increased. From time (t₅), which represents the lower turning point of the ring bank, the speed is reduced again until time (t₆) the end of the lower embankment area (B₂) is reached and the spindle speed is increased again. The variation to take account of the embankment areas (B₁, B₂) is thus superimposed on the variation to take account of the axial length of the thread balloon.

Claims (3)

1. Method for varying the rotational speed of spindles (17) of a draw-twisting machine with a plurality of workstations which each have a delivery device, running essentially at a constant speed, for delivering a monofil or multifil continuous filament (10), a ring-traveller arrangement (13, 15) with a ring rail (16) executing lifting movements, and a spindle (17) winding up the continuous filament (10) to form a bobbin (14) and having a drive (18) of variable rotational speed, the lifting movements of the ring rail (16) being controlled in such a way that, in the course of the draw-off, the winding plane is guided repeatedly into at least one of the resulting slope regions (B₁, B₂) of the bobbin package, the rotational speed of the spindles being gradually reduced with an increasing mean winding diameter of the bobbin, characterized in that, during each lifting movement of the ring rail, the rotational speed of the spindles (17) is reduced with an increasing distance between the delivery device and ring-traveller arrangement (13, 15) and is raised with a decreasing distance, and in that, during the displacement of the winding plane into the slope region (B₁, B₂), the rotational speed of the spindles (17) is raised with a decreasing winding diameter and is reduced with an increasing winding diameter.
2. Method according to Claim 1, characterized in that the thread tension in the continuous filament (10) delivered to the bobbins (17) is recorded at at least one workstation, and in that a regulation of the spindle rotational speed is carried out in order to keep the thread tension constant.
3. Method according to Claim 1, characterized in that the increasing winding diameter of the bobbins and the height position of the ring rail are recorded, and in that, independently thereof, a predetermined desired value of the spindle rotational speed is followed.

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