EP0289010B1 - Method and device for controlling and maintaining a predetermined yarn quality - Google Patents

Abstract

To control the yarn quality of a yarn produced by a textile machine, particularly a false-twist jet spinning apparatus, there is provided at the end of the spinning operation, however, upstream of the pair of withdrawal rolls for the outfeed of the produced yarn, a yarn tension measuring device. Upon falling outside of a predeterminate yarn tension tolerance or tension range the yarn tension measuring device controls operation of the false-twist jet spinning apparatus such that, as required, there is accomplished an appropriate increase or decrease of the yarn tension of the yarn produced by the false-twist jet spinning apparatus. Alteration of the yarn tension can be achieved, for instance, by varying the blowing intensity or energy of the air utilized for the spinning operation as well as by varying the angle at which there is blown in the air used for the spinning operation or by varying the rotational speed of the delivery rolls which deliver the formed yarn or by selected combinations of these measures.

Description

The invention relates to a method for monitoring and maintaining a predetermined yarn quality of a yarn produced by means of a false twist nozzle spinning device and a spinning device for carrying out the method.

In the production of yarn, the uniformity of the yarn quality per spinning station and in the comparison of the individual spinning stations with one another plays an important role.

With the known methods, for example with a method or a device according to EP-A-0 131 170, it is difficult to keep the desired yarn quality within relatively narrow limits, or rapid adaptation of the manufacturing process to fluctuations in the yarn quality is not readily possible possible, which are due to variations in the quality, length, strength or other properties of the spun fibers.

It is therefore an object of the invention to remedy this.

According to the invention, the object is procedural solved that the yarn quality is determined by measuring the mechanical tension in running yarn and this measured value is compared in a control with a predetermined tension value, and that the energy of the compressed air blown into the false twist spinneret is changed by means of the control when the measured thread tension exceeds or falls below a predetermined tolerance range.

• sie zumindest ein Streckwerk, eine Falschdrall-Spinndüse und ein Abzugswalzenpaar umfaßt,
• zwischen dem Ende der Spinndüse und dem Abzugswalzenpaar ein Meßelement zur Messung der Fadenspannung vorgesehen ist, und
• das Meßelement an einer Steuerung angeschlossen ist, welche einen an ein Mittel zur Änderung der Fadenspannung angeschlossenen Ausgang aufweist, wobei dieses Mittel die Energie der in die Spinndüse eingeschlossenen Druckluft verändern läßt.

In terms of the device, the solution to the problem is characterized in that

• it comprises at least one drafting device, a false twist spinneret and a pair of draw-off rollers,
• a measuring element for measuring the thread tension is provided between the end of the spinneret and the pair of draw-off rollers, and
• the measuring element is connected to a controller which has an output connected to a means for changing the thread tension, this means allowing the energy of the compressed air enclosed in the spinneret to change.

In this case, display means for displaying the thread tension or control means can be provided in order to actuate the means for changing the thread tension on the basis of the measurement signal mentioned.

A method and a device for monitoring and maintaining a predetermined yarn quality when producing a yarn is known from DE-A-3 424 709, but this document is concerned with friction spinning. In the method known from this document, the yarn quality is determined by measuring the mechanical tension of the running yarn and the value of this measurement is compared with a predetermined tension value and at Falling below or exceeding a predetermined tension tolerance correspondingly acting on the spinning device to increase or decrease the tension. More specifically, DE-A-3 424 705 describes an OE friction spinning machine with a large number of spinning units, each of which has an individual drive for the friction rollers and for the pair of take-off rollers. A single drive for the feed rollers can also be provided. A yarn monitor is provided between the friction rollers and the pair of take-off rollers and is connected to a control unit. Based on the continuously measured thread quality (thread tension; thick and thin places), the speed of the drives for the friction rollers, take-off rollers and feed rollers is regulated or changed.

It can therefore be seen from this document that the take-off speed is decisive for the quality of the spun thread.

Further advantageous embodiments of the method according to the invention and the device according to the invention are defined in the further dependent claims.

Fig. 1

ein Längsschnitt durch eine erfindungsgemäße Düsen-Falschdrall-Spinnvorrichtung, halbschematisch dargestellt,

Fig. 1a

ein Querschnitt (ohne Schnittschraffierung) durch die Vorrichtung von Fig. 1, gemäß der Linie II (Fig. 1).

The invention is explained in more detail below with the aid of drawings which only show execution routes.
It shows:

Fig. 1

3 shows a longitudinal section through a false twist spinning device according to the invention, shown semi-schematically,

Fig. 1a

a cross section (without hatching) through the device of Fig. 1, along the line II (Fig. 1).

The false twist spinning device shown with FIGS. 1 and 1a comprises a drafting device 50, a false twist spinneret 51, a yarn guide tube 52 connected thereto and a pair of draw-off rollers 53.

From the drafting unit 50, only the pair of output rollers 54 and the fiber guide straps 55 are shown.

The false twist spinneret comprises an insertion part 56, a guide screen 57 and a swirl generating part 58.

In the inlet following the guide screen 57, viewed in the thread running direction K, of the swirl-generating part 58, a compressed air inlet channel 59 opens, through which compressed air is conveyed by means of an injection nozzle 60 which can be adjusted in the blowing direction. The ratio of the diameter to the length of the compressed air inlet channel must be selected such that the compressed air flow blown in by the injection nozzle 60 is not disturbed either by the walls or by the mouth of the compressed air inlet channel 59.

The injection nozzle 60 is provided in a spherical or hemispherical nozzle body (only the first shown) which is rotatably mounted in the false twist spinneret 51 in the manner of a joint ball.

In order to adjust the nozzle body 61, the latter has an adjusting lever 62 which, via a triple ball joint 63, has a horizontally lying servomotor 64 (FIG. 1a) and is connected to a vertical servomotor 65 (FIG. 1). The terms lying horizontally and standing vertically are to be understood with reference to FIG. 1. Triple ball joint is to be understood as a ball with a hollow ball placed over it as a pan and a second pan placed over the hollow ball, for example the actuating lever 62 with the ball and the servomotors 64 or. 65 are each connected to a pan.

Each actuator 65 respectively. 64 is at its end opposite the triple ball joint 63 by means of a single ball joint 66 and. 78 in a fixed housing part 67 respectively. 79 stored.

After the yarn feed tube 52 and before the draw-off roller pair 53, a thread tension measuring device 68 is provided, which emits measurement signals 69 into a control 70, which is not the subject of the invention. Such devices are known per se and are available on the market, for example, under the brand name Electronic Tensiometer R-1192 from Rothschild, Traubenstrasse 3, CH-8002 Zurich.

Furthermore, the injection nozzle 60 is connected to an adjustable pressure regulating valve 71, which is supplied with compressed air from a compressed air source 72.

The draw-off roller pair 53 is driven by a drive motor 73.

The controller 70 processes the measurement signals 69 into an output signal 74 for controlling the servomotor 64, an output signal 75 for controlling the servomotor 65, an output signal 76 for controlling the pressure regulating valve 71 and an output signal 77 for speed control of the drive motor 73.

With the help of the actuators 64 and 65, an injection angle α (FIG. 1) and an injection angle β (FIG. 1a) are set.

The injection angle α is located in an imaginary plane W, which contains the axis of symmetry 84 (FIGS. 1 and 1a) of the injection nozzle 60 and which either lies parallel to the axis of symmetry 83 (FIGS. 1 and 1a) of the guide screen 57 or contains this.

In this plane the angle α is formed by the axis of symmetry 84 and a straight line (not shown) which is either parallel to the axis of symmetry 83 if the plane W is parallel to the axis of symmetry 83, or coaxial with the axis of symmetry 83 if the plane W includes the axis of symmetry 83. The injection angle β is formed by the plane W and by another imaginary plane T, which contains the axis of symmetry 83. The angle β then forms a right angle (90 ° angle) if the plane W also contains the axis of symmetry 83. The smallest angle β is formed when the plane W is parallel to the axis of symmetry 83 in such a way that the air jet from the injection nozzle 60 enters the swirl-generating nozzle 58 essentially tangentially.

By blowing compressed air into the swirl generating part 58 with the injection angles α and β preselected less than 90 degrees, in addition to a crank-like twisting action on the yarn mentioned later, a suction effect for the introduction part 56 is created, so that air passes through this part from the output rollers 54 is sucked in here.

This air blown in via the injection nozzle 60 plus the air drawn in through the introduction part 56 flows through the swirl generating part 58 and leaves the yarn guide tube 52 at its outlet mouth 80.

In operation, a sliver (not shown) is fed into the drafting device 50 and hidden therein by a desired amount. At the exit of the drafting device 50, the output rollers 54 feed a fiber sliver fanned out to a desired width (not shown) into the insertion part 56, which sliver guides this sliver against the guide screen 57 with the aid of the sucked-in air. With the aid of this diaphragm, a yarn core is produced in a manner known per se, which is grasped by the air flow of the injection nozzle 60 when it enters the swirl generating part and rotated like a crank. This crank-like rotation results in a rotation in the yarn core which continues counter to the thread running direction R back to the clamping line of the pair of outgoing rollers 54.

In itself, this process includes the winding of the twisted core with edge fibers of known prior art and for example in European patent application no. 0131170 published. Further examples are listed in an article written by Prof. Hans W. Kraus and published in "Mellisand Textile Reports 1/1987".

Assuming a constant feed speed of the output roller pair 54, the thread tension in the area of the thread tension measuring device 68 can be changed either by changing the angles α and β and / or the air throughput (m³ / min.) Through the injection nozzle 60 and / or the speed of the take-off roller pair 53 will.

By changing the angles α and β and the blowing intensity in the blowing nozzle 60, the crank effect and the conveying effect on the yarn 81 in the thread running direction R can be changed, while the speed change of the take-off rollers 53 changes the so-called spinning distortion, with the spinning delay being the The ratio of the speed of the yarn 81 on the take-off rollers 53 to the speed of the sliver 82 on the output roller pair 54 is understood.

• a) die Einblasintensität an der Einblasdüse 60, bei gleichbleibendem Winkel α und β und gleichbleibendem Spinnverzug, innerhalb einer dafür vorgesehen Toleranz reduziert werden, oder
• b) der Winkel α, bei gleichbleibender Einblasintensität und gleichbleibendem Winkel β und Spinnverzug, innerhalb einer dafür vorgesehenen Toleranzbreite verkleinert werden, oder
• c) der Winkel β , bei gleichbleibender Einblasintensität und gleichbleibendem Winkel α und Spinnverzug, innerhalb einer dafür vorgesehenen Toleranz vergrößert werden, oder
• d) die Drehzahl der Abzugswalzen 53, bei gleichbleibender Einblasintensität, gleichbleibenden Winkeln α und β und gleichbleibender Geschwindigkeit des Faserbandes 82 am Ausgangswalzenpaar 54, innerhalb einer ebenfalls dafür vorgesehenen Toleranz verkleinert werden, oder
• e) die Spinngeschwindigkeit bei gleichbleibenden vorgenannten Maßnahmen und gegebener Garnnummer bis zum Einpendeln in die gegebene Fadenspannungs-Toleranz verkleinert werden.

If, for example, the thread tension measuring device 68 emits a signal during operation, which the controller 70 judges to be too high beyond the thread tension tolerance, either:

• a) the blowing intensity at the blowing nozzle 60, with constant angles α and β and constant spinning, are reduced within a tolerance provided for it, or
• b) the angle .alpha., with constant blowing intensity and constant angle .beta. and spinning delay, can be reduced within a tolerance range provided for this purpose, or
• c) the angle β, with constant injection intensity and constant angle α and spinning, are increased within a tolerance provided for it, or
• d) the speed of the take-off rollers 53, with constant blowing intensity, constant angles α and β and constant speed of the sliver 82 on the output roller pair 54, are reduced within a tolerance also provided for this purpose, or
• e) the spinning speed can be reduced with the above-mentioned measures and given thread number until they settle into the given thread tension tolerance.

If, on the other hand, the thread tension is too low, the opposite measures are taken.

It goes without saying that a combination of the aforementioned measures can also be taken if a single measure alone does not lead to the goal.

Measures a), c) and d) are particularly preferred since this enables a particularly controllable setting of the yarn quality.

A simplified variant of the device shown in FIGS. 1 and 1a consists in that the nozzle body 61 can only be moved in the direction of movement of the angle α. This eliminates the servomotor 64 with everything that is required for its function. In addition, the servomotor 65 may no longer be supported on the ball joint 66, but must be pivotably mounted (not shown) in such a way that the injection nozzle can only be moved in the range of the angle α.

The control 70 shown for the false-twist nozzle spinning device of FIGS. 1 and 1a is intended as an individual control per so-called spinning station (a plurality of spinning stations result in a spinning machine). However, it is understood that such a solution is expensive and is not absolutely necessary due to the usually slow voltage changes.

It is therefore known from the rotor-open-end spinning process that so-called traveling devices carry out control and operating functions on respective spinning units, as a result of which an optimization in terms of the cost and frequency of the operations to be carried out per spinning station can be achieved.

It is therefore understood that a whole series of variations can be provided in connection with traveling devices, for example that all servomotors provided for the adjustment of the elements are provided per spinning station and that only the thread tension measurement and the control of the traveling device are assigned, which mechanically represents the simplest solution.

Another variant is that a traveling device only measures the thread tension and displays it by display means (not shown) and that the elements to be adjusted in order to change the thread tension are operated manually until the thread tension is again within the given tolerance range.

Another application of the thread tension measurement consists in the simple monitoring of the spinning position by means of the thread tension measurement, that is to say that none of the measures mentioned for changing the thread tension are carried out and it is decided on the basis of the given thread tension tolerances to shut down the spinning position in order to remedy corresponding defects .

It is therefore understood that the inventive concept to use the thread tension to the corresponding spinning device on a yarn quality level hold, which corresponds to the desired yarn quality, is not limited to the examples shown and described.

Claims (10)

1. Method for monitoring and maintaining a predetermined yarn quality of a yarn (81) produced by a false-twist jet spinning device, characterised in that the yarn quality is determined by measuring the mechanical tension in the running yarn (81) and this measured value is compared with a predetermined tension value in a control unit (70), and that the force of the compressed air injected into the false-twist spinning jet (51) is altered by means of the control unit (70) if the measured yarn tension exceeds or falls below a predetermined tolerance range.
2. Method according to claim 1, characterised in that the injection direction (α; β) of the compressed air is altered by the control unit (70) if the measured yarn tension exceeds or falls below a predetermined tolerance range.
3. Method according to claim 1 or 2, characterised in that the rotational speed of the draw-off rollers (53), which draw off the spun yarn (81), is altered by the control unit (70) if the measured yarn tension exceeds or falls below a predetermined tolerance range.
4. Method according to one of the preceding claims, characterised in that the mechanical tension is continuously measured and the yarn quality continuously controlled.
5. Method according to one of claims 1 to 3, characterised in that the mechanical tension is measured intermittently.
6. Method according to claim 4 or 5, characterised in that the spinning device is stopped to eliminate defects if the measures taken are not sufficient to maintain the yarn quality within the predetermined tolerance range.
7. False-twist jet spinning device for carrying out the method according to one of the preceding claims, which comprises at least one drawing system (50), one false-twist spinning jet (51) and one draw-off roller pair (53), characterised in that

   - a measuring element (68) is provided between the end of the spinning jet (51) and the draw-off roller pair (53) to measure the yarn tension, and

   - the measuring element (68) is connected to a control unit (70) which comprises an output which is connected to a means (71) for altering the yarn tension, which means (71) enables the force of the compressed air in the spinning jet (51) to be altered.
8. Jet spinning device according to claim 7, characterised in that a further means (64; 65) is provided to alter the yarn tension, which means enables the injection direction (α; β) of the compressed air to be altered.
9. Jet spinning device according to claim 7 or 8, characterised in that a further means (73) is provided to alter the yarn tension, which means enables the rotational speed of the draw-off rollers (53), which draw off the spun yarn (81), to be altered.
10. Spinning machine with a plurality of spinning devices according to one of claims 7 to 9, characterised in that an automatic traveller, which can move along the spinning machine, is provided, the yarn tension measuring and control equipment being associated with the automatic traveller and not provided as individual control equipment for each spinning device.

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