METHOD FOR CALIBRATING A THREAD STORAGE UNIT

Abstract

A method for calibrating a thread storage unit that can be arranged at a workstation of a textile machine. The method comprises the calibration steps of: setting of a calibration torque of the electric motor in the control system, wherein the calibration torque is lower than the maximum torque acting on the thread guide arm due to the magnetic repelling effect of the coupling elements;activation of the electric motor of the drive unit for adjusting the thread guide arm with the calibration torque to a rest position against a stop of the thread guide unit by the control system; andstorage of the set position of the thread guide arm and the electric motor as the zero position of the thread guide arm and the electric motor in the control system.

Description

The invention relates to a method for calibrating a thread storage unit that can be arranged at a workstation of a textile machine, comprising

• • a thread guide arm that is mounted in a manner freely rotatable about a pivot axis with a magnetically acting first coupling element arranged at a distance from the pivot axis,
  • a drive unit having a controllable electric motor for reversibly pivoting the thread guide arm, wherein the drive unit has a second magnetic coupling element that is arranged so as to be adjustable relative to the first coupling element, acts in a magnetically repelling manner on the first coupling element and is arranged on the drive unit so that it can be brought into operative connection with the first coupling element, wherein an adjustment of the second coupling element in the direction of the first coupling element causes a displacement of the first coupling element in the same direction,
  • a sensor unit for detecting the rotational movement and/or position of the thread guide arm and
  • a control system assigned to the workstation for controlling the drive unit and for evaluating the sensor information for identifying the thread tension exerted on the thread.

In connection with workstations, in particular with spinning and/or winding stations of a textile machine, for example spinning machines and winding machines, it is known to mount a controlled thread storage unit for winding bobbins, for example, conical cross-wound bobbins, upstream from the traversing devices along a thread running path. These thread storage units serve to adapt the thread sags occurring when winding the bobbins at the constant thread feed speed of a spinning device or spinning cop draw-off device, for example. In the known textile machines, the run-on bobbin is usually held in a pivotably mounted bobbin frame of a winding device downstream from the traversing devices during the winding process or the bobbin travel and is usually driven by a friction roller via a frictional connection or individually.

Specifically, the winding speed of the run-on bobbin corresponds to the constant thread feed speed by, for example, the spinning device depending on its wound diameter. During winding, the thread is laid over the bobbin width defined, in particular crosswise, by means of the traversing device. Due to the constant thread feed speed, a periodic loosening of the thread occurs, which is why there is the need to compensate for the sag while shortening the working path of the thread along the thread running path in order to maintain a desired thread tension.

In addition to compensating for the thread sag, it is indispensable to keep the thread tension substantially constant during the winding process. From the prior art, such as for example EP 4 101 800 A1, it is already known to design thread storage units with a thread guide arm which is pivoted into the region of the thread running path and thus temporarily extends the length of the regular working path of the thread in a loop-forming manner. The thread guide arm can be pivoted and positioned about a pivot axis transverse to the thread running path via a controllable electric motor of a drive unit. The control for the electric motor is effected via a control system that evaluates sensor information from a sensor unit for detecting the rotational movement and/or position of the thread guide arm for identifying the thread tension exerted on the thread.

In order to accurately determine the thread tension acting on the thread guide arm by means of the thread guide unit during operation of the workstation, it is essential to calibrate the thread guide unit beforehand, in the course of which the relative position of the thread guide arm relative to the thread storage unit and the position of the electric motor resulting from the distance between the coupling elements and the assigned motor torque are detected for the position of the thread guide arm. Such a calibration is a prerequisite for ensuring that similar thread storage units, i.e., those that have a matching structure, coupling elements and electric motor, consistently ascertain the actual thread tension on the basis of characteristic curves previously detected for such thread storage units. The characteristic curves of the magnetic spring force, which can be used by the control system to infer the tensile force acting on the thread and consequently the thread tension, are stored in the control system or in a readable memory unit coupled to the control system.

With currently known methods for calibrating the thread storage units with magnetically acting coupling elements, the control system controls the motor such that both the thread guide arm rests against a stop of the thread guide unit and the magnetic coupling elements of the thread guide arm and the drive unit rest against each other. This position of the thread guide arm and the electric motor is stored in the control system as the zero position.

However, with such a calibration, tolerances in the magnetic force and in the mounting of the magnets on the thread guide arm and the drive unit mean that in this zero position, in which the magnets of the thread guide arm and drive unit are in contact with each other, the same repelling forces do not prevail between the coupling elements for every combination thread storage unit. After the ratio of the force applied by the motor to the distance between the coupling elements to determine the effective spring tension is compared with the characteristic curve in the control system that applies to all combination thread storage units of the same design, the result is that different combination thread storage units of the same design deliver different thread tension results.

Based on this, the invention is based on the object of providing a method for calibrating a thread storage unit that enables a reliable ascertainment of the thread tension. The invention achieves the object by a method with the features of claim 1 and by a workstation with the features of claim 3. Advantageous further developments of the method and of the workstation are given in the respective dependent claims.

The method for calibration according to the invention is characterized by the calibration steps of

• • setting of a calibration torque of the electric motor in the control system, wherein the calibration torque is lower than the maximum torque acting on the thread guide arm due to the magnetic repelling effect of the coupling elements,
  • activation of the electric motor of the drive unit for adjusting the thread guide arm with the calibration torque to a rest position against a stop of the thread guide unit and
  • storage of the set position of the thread guide arm and the electric motor as the zero position of the thread guide arm and the electric motor in the control system.

The method according to the invention provides that, in order to carry it out, a calibration torque is set for the electric motor which is less than the maximum torque resulting from the magnetic repelling effect of the coupling elements and which acts on the thread guide arm in the opposite direction to the calibration torque. The calibration torque is preferably already stored in the control system, so that the setting of the calibration torque is automatically set or specified by the control system when the calibration process is initiated.

By setting or selecting the calibration torque according to the invention, an adjustment of the thread guide arm is achieved during the calibration process, as a result of which the thread guide arm rests against a stop of the thread guide unit, but at the same time the first coupling element of the thread guide arm and the second coupling element of the drive unit are arranged at a distance from each other. The setting position of the electric motor, which is subsequently stored in the control system as the zero position of the electric motor, corresponding to the zero position of the thread guide arm, in which it rests against the stop of the thread guide unit, is thus determined solely by the calibration torque applied by the electric motor and the opposing torque acting on the thread guide arm generated by the repelling effect of the coupling elements. Any tolerances, for example when mounting the coupling elements on the drive unit and the thread guide arm, can thus be disregarded. Based on the zero positions of the thread guide arm and the electric motor ascertained in this way, the characteristic curve stored in the control system or a memory unit connected to the control system for such thread storage units can be used to reliably ascertain the thread tension acting on the thread guide arm for each position of the thread guide arm.

According to a further development of the invention, it is provided that the calibration torque is set such that the coupling elements have a distance of 1 to 6 mm, preferably 1 to 4 mm, particularly preferably 1 to 2 mm in the rest position. The setting of a corresponding calibration torque or its selection, if this is stored in the control system or a memory unit connected to the control system, ensures in particular that the torque acting in the opposite direction to the calibration torque results solely from the repelling effect of the coupling elements. Starting from the specified zero position, there is also a wide pivot range of the thread guide arm relative to the drive unit, in which the coupling elements interact with each other and in which the thread tension can be reliably inferred from the existing repelling effect, taking into account the characteristic curve.

In principle, a calibration of the thread storage unit can already be effect after it has been assembled, i.e., prior to its mounting at the workstation, so that the calibration according to the invention ensures that similar thread storage units in the installation position display the same thread tension for similar load conditions in the correct manner.

According to a further development of the invention, it is provided that, prior to carrying out the calibration, the thread storage unit is mounted at the workstation. This embodiment of the invention makes it possible to dispense with a separate control system, which is used to operate the thread storage unit and to carry out the calibration process prior to activation. The further development according to the invention makes it possible to operate and calibrate the thread storage unit with a control system that is arranged separately from the thread storage unit. Thus, according to this further development of the invention, the control system can be provided in a workstation, which comprises the thread storage unit, in a central machine control system and/or away from the textile machine. The control system can preferably comprise a control unit along with an evaluation and assessment unit, which can be one and the same unit or different units. Two units having an individual unit can also be realized. A redundant control by providing two control systems that check or can check each other can also be possible.

Characteristic of the workstation according to the invention with a thread storage unit, which comprises

• • the thread guide arm, which is freely rotatable about a pivot axis, with the magnetically acting first coupling element arranged at a distance from the pivot axis,
  • the drive unit comprising the controllable electric motor for the reversing pivoting of the thread guide arm, wherein the drive unit has the second magnetic coupling element that is arranged so as to be adjustable relative to the first coupling element, acts in a magnetically repelling manner on the first coupling element and is arranged on the drive unit so that it can be brought into operative connection with the first coupling element, wherein an adjustment of the second coupling element in the direction of the first coupling element causes a displacement of the first coupling element in the same direction,
  • the sensor unit for detecting the rotational movement and/or position of the thread guide arm and
  • the control system assigned to the workstation for controlling the drive unit and for evaluating the sensor information for identifying a thread tension exerted on the thread

is that the control system is designed to carry out the method according to the invention or further developed method described above.

The workstation according to the invention ensures, through the possibility of calibrating the thread storage unit, that the actual thread tension is ascertained in a reliable manner.

According to a further development of the invention, it is provided that the thread storage unit is arranged at the workstation such that the thread guide arm is arranged in the rest position in a position crossing the thread running path, into which position the thread guided by the thread guide arm is pushed out of the thread running path during the bobbin travel. Accordingly, the thread storage unit is arranged with the thread guide arm along the thread running path such that the rest position of the guide arm, which corresponds to its zero position and the zero position of the electric motor, lies outside the thread running path and in the direction in which the thread guide arm pushes the thread out of the thread running path. This can ensure that the thread guide arm can be reset solely via the force effect of the thread generated in the direction of the thread running path when it deflects the thread running path.

An exemplary embodiment of the invention is explained below with reference to the drawings. In the drawings:

FIG. 1 shows a perspective schematic view of a thread storage unit according to an exemplary embodiment;

FIG. 2 shows a perspective schematic view of an enlarged representation of a partial region of the thread storage unit of FIG. 1;

FIG. 3 shows a perspective schematic view of an enlarged representation of the thread storage unit of FIG. 1 without a thread guide arm,

FIG. 4 shows a perspective schematic representation of the thread guide arm of the thread storage unit of FIG. 1, and

FIG. 5 shows a schematic perspective view of the thread storage unit shown in FIG. 1 in an arrangement upstream of the paraffin application device.

FIG. 1 shows a perspective schematic view of a thread storage unit 1 according to an exemplary embodiment which is connected to a connection plate 17 for arrangement at a workstation, in particular, a spinning or winding station of a textile machine (not shown here). FIGS. 2 to 4 show a perspective schematic view of an enlarged representation of a partial region of the thread storage unit 1 shown in FIG. 1, and a perspective schematic representation of a thread guide arm 2 of said thread storage unit 1.

The thread storage unit 1 has a thread guide arm 2, which is arranged at the workstation with a thread guide eye 13 arranged at its free end in the thread running path F of a thread to be wound onto a run-on bobbin, wherein the thread is guided through the thread guide eye 13. In order to form a thread storage, the thread guide arm 2 is mounted pivotably on a drive shaft 16 of an electric motor 5 of a drive unit 4 of the thread storage unit 1, wherein for this purpose, the thread guide arm 2 has a bushing 18 for arrangement on the free end of the drive shaft 16, so that the thread guide arm 2 is mounted on the drive shaft 16 in a torque-free manner. The bushing 18 is furthermore connected to a holder 9 connected to the thread guide arm 2, which holder has an opening for receiving a first coupling element 6 designed as a permanent magnet.

The drive shaft 16 of the electric motor 5 is non-rotatably connected to a coupling disk 14, which is arranged coaxially to the drive shaft 16 for the thread guide arm 2 to pivot to form a loop during operation. A support 8, which has a further bushing 12 for receiving a further permanent magnet as the second coupling element 7, is arranged on the coupling disk 14. The permanent magnets on the thread guide arm 2 and the support 8 are oriented relative to each other such that they exert a magnetic repelling effect on each other. A rotation of the coupling disk 14 via the reversing electric motor 5 thus causes a corresponding contact-free pivoting of the thread guide arm 2 about the drive shaft 16, which defines a pivot axis S, wherein the electric motor 5 is controlled via a control system (not shown here) via the connection 19.

A sensor unit 3 arranged above—in relation to the drawing—the drive shaft 16 on a housing cover 11 of the housing 10 serves to detect the position of the thread guide arm 2, and is arranged with its sensor detecting the pivot angle coaxially to a connecting element 15 connected to the thread guide arm 2, which in turn extends in the longitudinal axis direction of the drive shaft 16.

The sensor unit 3 can be used to particularly reliably determine at least the rotational movement or the position of the thread guide arm 2, and to detect deviations of the thread guide arm 2 from the position set by the drive unit 4 by transmitting corresponding sensor information about the above to the control system. If, for example, the thread tension increases, then this causes a displacement of the thread guide arm 2 in the direction of the second coupling element 7 against the spring force generated by the magnetic repelling effect. On the basis of this, a return displacement of the coupling disk 14 can then take place via the control system. If, for example, the thread tension decreases while a thread is sagging, then this causes a displacement of the second coupling element 7 through a rotation of the drive shaft 16 and the support 8 coupled thereto together with the coupling disk 14 and the permanent magnet in the direction of the thread guide arm 2. Due to the magnetic repelling effect, the thread guide arm 2 is moved in the same direction, whereby the guided thread is pushed out of its thread running path F or further away therefrom, and a thread loop is formed or enlarged. A substantially constant thread tension can thus be achieved and ensured during the entire winding process or bobbin travel.

FIG. 5 shows a schematic perspective view of an exemplary embodiment of an arrangement of the thread storage unit 1 at the workstation (not shown), wherein the workstation can be a spinning or winding station. The thread storage unit 1 is arranged along a thread running path F, which runs from a thread feed device (not shown) in the direction of a traversing device (not shown) upstream of a paraffin application device 20, which is arranged upstream of the traversing device along the thread running path F and is only shown schematically and in excerpts. The paraffin application device 20 has a holder 22 underneath on which two thread guide rollers 21 are rotatably held, via which the thread can be guided along the thread running path F in a partially wrapped manner. The thread storage unit 1 is positioned on the thread running path F such that the thread guide arm 2 can pivot into the thread running path F with its guide eye 13 in order to push the running thread out of its thread running path F transverse to the direction in which the thread guide rollers 21 are arranged. As a result of being pushed out of its thread running path F by the thread storage unit 1, the thread comes into contact with the thread guide rollers 21, as a result of which a thread loop of a defined size is formed between the thread guide rollers 21. The size of the thread loop is varied as required by means of the thread storage unit 1 depending on the detected rotational movement or position of the thread guide arm 2 via the control system, which controls the electric motor 5 and consequently the thread guide arm 2, for setting and regulating a thread tension that is advantageously kept constant for the bobbin travel.

To calibrate the thread storage unit 1, a calibration torque of the electric motor 5 is set via a control system (not shown here), or a calibration torque stored in the control system or in a memory unit connected to the control system is selected. The calibration torque is such that the thread guide arm 2 is brought into contact with the inner side of the housing 10 by subsequently activating the electric motor 5 with the calibration torque. In the rest position of the thread guide arm 2 that is then set, the first coupling element 6 is also located at a distance from the second coupling element 7. The position of the thread guide arm 2 and the electric motor 5 is therefore determined solely by the calibration torque applied by the electric motor 5 and the magnetic forces acting between the coupling elements 6, 7. The setting position of the electric motor 5 and the thread guide arm 2 in the rest position are stored in the control system as the zero position of the thread guide arm 2 and the zero position of the electric motor 5.

Taking into account a known characteristic curve of the magnetic spring force previously stored in the control system or in a read-out memory unit coupled to the control system, the control system can be used to infer the thread tensile force acting on the thread and consequently the thread tension, taking into account the position of the thread guide arm 2 and the electric motor 5. The calibration of the thread storage unit 1 of a textile machine with a plurality of workstations ensures reliable detection of the correct thread tension for all workstations.

LIST OF REFERENCE SIGNS

• • 1 Thread storage unit
  • 2 Thread guide arm
  • 3 Sensor unit
  • 4 Drive unit
  • 5 Electric motor
  • 6 First coupling element
  • 7 Second coupling element
  • 8 Support
  • 9 Holder
  • 10 Housing
  • 11 Housing cover
  • 12 Further bushing
  • 13 Thread guide eye
  • 14 Coupling disk
  • 15 Connection element
  • 16 Drive shaft
  • 17 Connection plate
  • 18 Bushing
  • 19 Connection
  • 20 Paraffin application device
  • 21 Thread guide roller
  • 22 Holder
  • F Thread running path
  • S Pivot axis

Claims

1. A method for calibrating a thread storage unit that can be arranged at a workstation of a textile machine, the method comprising: mounting a thread guide arm in a manner freely rotatable about a pivot axis with a magnetically acting first coupling element arranged at a distance from the pivot axis;providing a drive unit having a controllable electric motor for reversibly pivoting the thread guide arm, wherein the drive unit has a second magnetic coupling element that is arranged so as to be adjustable relative to the first coupling element, acts in a magnetically repelling manner on the first coupling element and is arranged on the drive unit so that the drive unit can be brought into operative connection with the first coupling element, wherein an adjustment of the second coupling element in a direction of the first coupling element causes a displacement of the first coupling element in the same direction;detecting a rotational movement and/or position of the thread guide arm with a sensor unit;assigning a control system to the workstation for controlling the drive unit and for evaluating sensor information for identifying a thread tension exerted on a thread;setting of a calibration torque of the controllable electric motor in the control system, wherein the calibration torque is lower than a maximum torque acting on the thread guide arm due to a magnetic repelling effect of the first coupling element and the second coupling element;activating the controllable electric motor of the drive unit for adjusting the thread guide arm with the calibration torque to a rest position against a stop of the thread storage unit by the control system; andstoring a set position of the thread guide arm and the controllable electric motor as a zero position of the thread guide arm and the controllable electric motor in the control system.

2. The method for calibrating according to claim 1, wherein the calibration torque is set such that the first coupling element and the second coupling element have a distance of 1 to 6 mm in the rest position.

3. The method for calibrating according to claim 1, wherein, prior to carrying out calibration, the thread storage unit is mounted at the workstation.

4. A workstation of a textile machine comprising: a thread storage unit;a thread guide arm mounted in a manner freely rotatable about a pivot axis with a magnetically acting first coupling element arranged at a distance from the pivot axis;a drive unit having a controllable electric motor for reversibly pivoting the thread guide arm, wherein the drive unit has a second magnetic coupling element that is arranged so as to be adjustable relative to the first coupling element, acts in a magnetically repelling manner on the first coupling element and is arranged on the drive unit so that the drive unit can be brought into operative connection with the first coupling element, wherein an adjustment of the second coupling element in a direction of the first coupling element causes a displacement of the first coupling element in the same direction;a sensor unit for detecting the rotational movement and/or position of the thread guide arm; anda control system assigned to the workstation for controlling the drive unit and for evaluating sensor information for identifying a thread tension exerted on the thread;wherein the control system is designed to carry out the method according to claim 1.

5. The workstation according to claim 4, wherein the thread storage unit is arranged at the workstation such that the thread guide arm is arranged in the rest position in a position crossing a thread running path, into which position the thread guided by the thread guide arm is pushed out of the thread running path during a bobbin travel.