RING FOR A RING SPINNING OR RING TWISTING MACHINE

Description

[0001] The invention relates to a ring for a ring spinning or ring twisting machine.

[0002] Rings are used as spinning rings in so-called ring spinning machines or as twisting rings in so-called twisting machines. The spinning or twisting rings interact with attached ring travelers. The ring travelers, carried along by the thread held by the ring traveler, rotate at high speeds on an upper side of the spinning rings, the so-called ring crown, which leads to high loads on the contact surfaces between the ring traveler and the ring crown of the spinning rings. To attach the spinning or twisting rings to the machine, a web is provided which can end in a base flange. The ring crown as well as the base flange, or in the absence of a base flange the web, are manufactured in a wide variety of designs, each adapted in shape and geometry to the requirements of the respective machine and the intended design for attaching the spinning or twisting ring. The spinning ring is held in the machine in a so-called ring frame.In the following, spinning rings and twisting rings are summarized under the term spinning ring.

[0003] During operation, the friction surfaces between the spinning ring and the ring traveler heat up, and with them the yarn. Due to the rapid rotation of the ring traveler on the spinning ring, local temperatures of over 400°C can occur, which place operational limits on the ring traveler-spinning ring system. Due to these mechanical conditions, ring travelers cannot speeds of more than 30,000 revolutions per minute without damaging the ring traveler or yarn. State of the art attempts were made to remedy this situation by using a rotating spinning ring. By using a rotating spinning ring, the relative speed between the ring traveler and the spinning ring is reduced, and as a result the speed of the ring traveler can be increased compared to a stationary spinning ring without the thermal load on the ring traveler-spinning ring system increasing.By increasing the speed of the ring traveler, the production of the spinning machine can also be increased accordingly.

[0004] Various designs of ring traveler-spinning ring systems with rotating rings are known from the prior art. For example, CN 109 763 220 A describes a spinning ring drive with a hollow-shaft motor. The hollow shaft of the motor attached to the ring rail is connected to the spinning ring in a rotationally fixed manner. The ring traveler can either rotate freely on the ring crown or be held stationary on the ring crown. Furthermore, utility model CN ​​208 266 341 U discloses a driven spinning ring, wherein the spinning ring is connected to the rotor of the electric motor, and the stator of the electric motor is attached to the ring rail via a housing of the electric motor. CN 108 301 078 A discloses a driven ring-traveler system that enables "high-speed operation" of the spinning machine and is intended to increase the service life of the ring traveler by reducing the relative speed between the spinning ring and the ring traveler.An arrangement for the ring traveler-spinning ring system includes the spinning ring for supporting the ring traveler, with the spinning ring mounted on the drive rotor. The rotor is held by a ball bearing in an outer ring, which is attached to the ring rail.

[0005] Siegfried et al. (IEEE Transactions on Industrial Electronics 61 (6), 2990-2997, 2014) demonstrate a high-speed drive with a frictionless suspension system for a rotor spinning unit. To achieve a very long service life, the rotor is suspended by active magnetic bearings.

[0006] EP2009153A1 shows a device for a ring spinning or twisting machine with a thread guide ring which has a thread guide element for twisting and deflecting a running thread and a receiving unit on which the thread guide ring is arranged so as to be rotatable about a provided axis of rotation, wherein force generating means are provided for applying axial forces to the thread guide ring.

[0007] WO2004 / 027129A2 shows a ring spinning system for producing yarn in which the ring traveler arrangement is replaced by a single rotating, floating ring with an eyelet on its inner central surface. A disadvantage of the known designs of driven spinning rings is their bearings. Roller bearings or roller bearing-like structures are provided to stabilize the spinning rings in the radial direction. This mechanical bearing, in turn, causes heating and limits the rotational speeds due to the mechanical properties of the partner materials in the mechanical bearing.

[0008] The object of the invention is to create a driven ring in which the possibility of increasing the speed is not hindered by mechanically generated frictional heat.

[0009] The problem is solved by the features in the characterizing part of the independent claim. To solve the problem, a novel drive for a ring for a ring spinning or ring twisting machine is proposed, comprising an electric drive with a stator and a rotor with a magnet, wherein the ring comprises a ring crown for supporting a ring traveler and a connecting section, and the ring is connected in a rotationally fixed manner to the rotor of the drive via the connecting section. The drive has a coil system for generating a torque and radial forces, wherein one axial degree of freedom and both tilting degrees of freedom of the rotor are passively stabilized by reluctance forces and both radial degrees of freedom are actively stabilized by a control loop. Drives with coil systems which enable the generation of torques and radial forces are known from the prior art and are referred to in the literature as bearingless motors.

[0010] The magnet firmly connected to the rotor generates an excitation magnetic field. This magnetic field stabilizes three degrees of freedom passively, i.e. without energizing the coils: these are the axial degree of freedom and the two tilting degrees of freedom. The two radial degrees of freedom are stabilized by suitable energization of the stator coils. The energization is adjusted in a control system depending on both the radial rotor position and the electrical angle of rotation of the rotor. The radial position (x and y directions) as well as the electrical angle of rotation of the rotor are continuously recorded by sensors. The control system determines the coil currents required to move the rotor into its force-free position in the xy plane. The current generated by this control is referred to as the force-current component. The mean value of the force-current component is approximately0 amps, because the rotor is held in its force-free position by the control system. In addition to the force-current component, the coils are also subjected to a torque-current component. This current component corresponds to the current used by a synchronous motor during operation. Therefore, all control methods known from the field of synchronous motors, such as field weakening to achieve higher speeds, are possible with the bearingless motor.

[0011] A bearingless motor can be implemented with a number of phases of less than or equal to four. Each phase can be constructed from a series and / or parallel connection of coils, as is common in motor technology. The individual coils can be arranged concentrically around a pole piece, but a distributed winding design is also possible.

[0012] A design with a number of 5 strands and 5 concentric coils is shown in Figure 9. Each coil has two current components as described: a force-current component for the radial bearing of the rotor and a torque-current component for driving and braking the rotor. Figure 10 An alternative embodiment is shown. Here, there is a separate coil for the force-current component and for the torque-current component. In comparison to Figure 9 This design has the disadvantage that more electronic components (usually power semiconductors) are required to control the coils.

[0013] Advantageously, the drive is designed as a bearingless disc rotor with a flat stator and the ratio of the axial length of the rotor magnet to the diameter of the rotor magnet is less than 0.4. The axial length and diameter specifications refer to the rotor magnet and not to the external dimensions of the entire rotor structure. A geometric parameter that has a decisive influence on the passive stability of the rotor is the axial length, or more precisely the ratio of the axial length to the diameter of the rotor disk or its magnet. Since changing the axial length also changes the maximum magnetic air gap flux of a pole pitch, a change in length also affects the actively stabilized degrees of freedom, i.e. the load capacity and motor torque. In this case, only the amplitudes of force and torque are changed, not their progression as a function of the rotor angle.For this reason, a change in the axial length must be taken into account when designing the bearing and motor with regard to the magnitude of the achievable force and torque. Regarding passive stabilization of the rotor's axial and tilting movements, a preferred ratio of the axial length to the diameter of the rotor magnet is 0.3, or, as the inverse of diameter to length, 3.

[0014] In an alternative design to the bearingless disc rotor with a flat stator, the drive is designed as a bearingless disc rotor with a temple-shaped stator. In this embodiment, the ratio of the axial length of the rotor magnet to the diameter of the rotor magnet is less than 0.4. In this case, too, the axial length and diameter refer to the rotor magnet and not to the external dimensions of the entire rotor assembly. The advantage of a drive with a temple-shaped stator is that the entire drive has a smaller external diameter than a disc rotor with a flat stator.This means that less space is required between the individual drives used in a ring spinning machine, which means that the spinning stations can be installed closer together and, for example, existing machines can be easily retrofitted with a ring according to the invention.

[0015] Preferably, the ring traveler is designed to be freely movable relative to the system on the ring crown. In this design, the ring traveler is dragged along the ring crown by the yarn. The driven ring allows a maximum differential speed between the ring crown and the ring traveler to be maintained, even though the ring traveler can be operated at a much higher speed relative to the ring rail than with a stationary ring.

[0016] In an alternative embodiment to a freely movable ring traveler, the ring traveler is fixed to the ring crown. In this embodiment, the ring traveler is not dragged along by the yarn independently of the movement of the ring crown. The rotation of the ring traveler is determined solely by the rotation of the spinning ring and thus of the drive rotor. In a preferred embodiment, the ring traveler and the ring crown are formed as a single piece.

[0017] Advantageously, an additional active magnetic bearing can be provided to stabilize the rotor's axial degree of freedom. An active axial magnetic bearing allows the stiffness and damping relevant to the axial vibration to be adjusted. This can increase the stability of the axial vibration, i.e., reduce the maximum axial deflection of the rotor. Furthermore, the rotor can be held in specific axial positions. The magnetic bearing incorporates a corresponding sensor for actively controlling the axial position.

[0018] Preferably, damping of the tilting oscillations is provided by means of a compensation means, wherein the compensation means has at least one electrical conductor loop separated from a winding. The use of such compensation means is known from the disclosure of EP 3 255 760 A1. The electrical conductor loop separated from the winding is, on the one hand, non-interlinked to the excitation magnetic field in a reference position of the rotational axis, and, on the other hand, interlinked to the excitation magnetic field in an actual position of the rotational axis tilted relative to the reference position in order to counteract the tilting. The mode of operation corresponds to the effect of an electrodynamic damper with the particular advantage that the damping effect increases with increasing speed.

[0019] Advantageously, an emergency bearing is provided, wherein the emergency bearing is formed from at least one slide ring fastened to the stator. The emergency bearing is made from a material with sliding properties, for example PTFE, and serves to hold the rotor in the correct position when the drive is de-energized. If forces act on the rotor which are greater than the forces of the magnetic bearing, the emergency bearing ensures that the rotor remains within the stator. For this reason, it is customary to provide an emergency bearing in both the radial and axial directions. In the event of a power failure, the DC link is usually supplied with electrical power through recuperation, i.e. targeted braking of the rotor, which means that the active radial magnetic bearing can continue to function.If the rotor speed falls below a certain limit speed, recuperation is no longer possible and the rotor falls into the radial emergency bearing.

[0020] For operation as a bearingless motor, only certain combinations of the number of rotor magnet poles and the number of stator strands are suitable. The minimum number of strands is 4. The following designs are possible in the range of 4 to 6 strands and 2 to 10 poles: 4 strands / 4 poles 5 strands / 2 poles 5 strands / 6 poles 4 strands / 4 poles 6 strands / 2 poles 6 strands / 6 poles 6 strands / 8 poles If the number of phases corresponds to the number of poles, the motor exhibits a single-phase characteristic. This means that at certain rotor rotation angles, the motor torque becomes zero. However, this property does not fundamentally preclude the use of this type of topology.

[0021] If the number of poles divided by two is an even number, the compensation means described in EP 3 255 760 A1 is not effective.

[0022] It has been found that it is advantageous if the rotor magnet has 6 poles and the stator has 4 to 6 strands. In an alternative embodiment, the rotor magnet has 4 poles and the stator has 4 strands.

[0023] Furthermore, a ring spinning machine with a ring rail is proposed, with at least one driven ring attached to the ring rail as described above. The stator is attached to the ring rail, for example, by clamping or screwing. An opening for the spindle is provided in the ring rail, which is concentric with the opening of the rotor. Gauges or positioning aids attached to the ring rail can be used for precise positioning of the drive or the ring.

[0024] Advantageously, damping of the driven ring bearing is provided by a damping element made of viscoelastic materials in the stator's mounting on the ring rail. The provision of damping in the mounting has the advantage that, on the one hand, rotor vibrations transmitted to the stator are converted into heat in the damping element, and, on the other hand, external vibrations are not transmitted to the rotor. Typically, damping elements made of butyl-based rubber are used here.

[0025] A ring twisting machine with at least one rubbed ring according to the above description is also claimed.

[0026] In the following, the invention is explained in more detail by means of drawings, which show: Figure 1 shows a schematic representation of a ring spinning machine; Figure 2 shows a schematic representation of a driven spinning ring according to the invention in a first embodiment; Figure 3 shows a schematic sectional representation at the point XX of the embodiment according to Figure 2 ; Figure 4 shows a schematic representation of a driven spinning ring according to the invention in a second embodiment; Figure 5 shows a schematic representation of a fastening of a driven spinning ring on a ring rail; Figures 6a, 6b show a schematic representation of a disc rotor with a flat stator in a first embodiment; Figures 7a, 7b show a schematic representation of a disc rotor with a temple-shaped stator; Figure 8 shows a schematic representation of the degrees of freedom; Figures 9a, 9b show a schematic representation of a disc rotor in a second embodiment and Figure 10 shows a schematic representation of a disc rotor in a third embodiment.

[0027] Figure 1shows a schematic representation of a spinning station of a ring spinning machine, whereby today's ring spinning machines have up to 2,000 such spinning stations. In the ring spinning machine, a fiber strand, a so-called sliver 1, is fed to a drafting system 2. The sliver 1 is drawn by the drafting system 2 into a thread 3. The drafting system 2 shown is a so-called apron drafting system, which is usually used for cotton. Depending on the application, many different types of drafting systems 2 are known from the prior art. After the drafting system 2, the thread 3 is guided via a thread guide 4 to a ring traveler 10. After passing the ring traveler 10, the thread 3 is wound onto the yarn spool 5. The yarn spool 5 is set in rotation 6 by a drive 7. Through this rotation 6 of the yarn spool 5, the ring traveler 10 is carried along by the thread 3, which results in the thread 3 being given a rotation and thus the yarn being formed.Because the ring traveler 10 is held on the spinning ring 8, the ring traveler 10 is forced to rotate around the yarn spool 5. The spinning ring 8 is held stationary on a ring frame 9.

[0028] Figure 2 shows a schematic representation of a driven ring according to the invention in a first embodiment in a plan view and Figure 3 shows a schematic sectional view at point XX of the embodiment according to Figure 2 . The stator 12 is fastened to a ring rail 9 by means of a fastening 18. The stator 12 shown as an example has a square shape and is held in place on the ring rail 9 by means of a fastening 18 in the form of a screw in each of its corners. A possible embodiment of this fastening is shown in Figure 5shown. A rotor 13 is arranged within the stator 12, wherein the stator 12 together with the rotor 13 form the drive 11. The magnet 17 is connected to the rotor. The rotor 13, or rather its magnet 17, has an axial length L and a diameter D. The magnet 17 has a number of poles of, for example, 4, 6 or 8. The magnet 17 can be designed as a single ring or from segments. The stator 12 and the rotor 13 are arranged concentrically around an axis of rotation 14 of the spinning ring 8. Also arranged concentrically to the drive 11 is a spinning ring 8, which is fixedly attached to the rotor 13 via a connecting section 16. The spinning ring 8 has an annular crown 15 on which a ring traveler 10 is movably mounted.

[0029] Figure 4shows a schematic representation of a driven ring according to the invention in a second embodiment. Shown are the rotor 13 with magnets 17 and the stator 12 arranged around the rotor 13. A spinning ring 8 with a ring crown 15 and a connecting section 16 is mounted on the rotor. The spinning ring 8 is fixedly connected to the rotor 13 via the connecting section 16. A ring traveler 10 is also fixedly attached to the ring crown 15. As a result, the rotor 13 is set in rotation and the spinning ring 8 as well as the ring traveler 10 attached to it are also set in rotation by the rotor 13. In contrast to the representation in Figure 3 the ring traveler 10 is not freely movable on the ring crown 15 but always has the same speed as the spinning ring 8 or the rotor 13.

[0030] Embedded in the stator 12 is the displacement sensor 22 for controlling the active radial magnetic bearing. Also attached to the stator 12 are the emergency bearings 20, which partially surround the rotor 13 and are arranged in the form of rings. The emergency bearings 20 act in both the radial and axial directions. An additional axial magnetic bearing 31 with an associated axial displacement sensor 21 is also shown. Embedded in the stator 12 is a compensation means 19 in the form of a conductor loop.

[0031] Figure 5shows a schematic representation of a fastening of a driven ring on a ring rail 9. The stator 12, which is equipped with a compensation means 19 and the radial displacement sensor 22, is provided with through openings and the ring rail 9 is provided with correspondingly arranged internal threads. The through openings have an enlarged diameter at both ends to accommodate damping means 23. The damping means 23 decouple the stator 12 from the ring rail 9 on the one hand and the stator 12 from the fastening 18 on the other. The fastening 18 is represented by a screw as an example. With a screw in the design shown, it is necessary to attach a damping means 23 to both ends of the screw, since otherwise the vibrations would be transmitted from the ring rail 9 via the screw body to the stator 12 (or vice versa).

[0032] The Figures 6a and 6bshow a schematic representation of a so-called bearingless disc rotor in a first embodiment. Shown are a top view and a cross-section of the disc rotor with a flat stator 12. The rotor 13 is arranged within the stator 12, and its magnet 17 has an axial length L and a diameter D. The rotor 13 and stator 12 are arranged concentrically around the rotational axis 14. The magnets 17 are shown schematically on the rotor 13, although the number of poles is not shown. The stator 12 is shown as a laminated core with windings 24 in five phases facing the rotor 13.

[0033] The Figures 7a and 7b show a schematic representation of a disc rotor with a temple-shaped stator 12. A top view and a cross-section of the disc rotor are shown. The design of the rotor 13, with its magnets 17 and its axial length L and diameter D, corresponds to the rotor 13 according to the Figures 6a and 6b .

[0034] In this embodiment, the stator 12 and the rotor 13 are also arranged concentrically around the rotational axis 14. However, the laminated core of the stator 12 is provided with a greater axial extension than the rotor 13, so that the windings 24, shown here as six strands, are arranged with an axial displacement along the rotational axis 14 with respect to the rotor 13.

[0035] Figure 8 shows a schematic representation of the degrees of freedom. For the sake of simplicity, the rotor 13 is shown as a cylindrical ring. The rotor 13 rotates around the rotational axis 14, with the rotational degree of freedom 25 being indicated. For all directions in Figure 8 However, the direction specifications also include the opposite direction. Furthermore, the two tilting degrees of freedom 27 and 28, as well as one axial degree of freedom 26 and both radial degrees of freedom 29 and 30, are specified.

[0036] The Figures 9a and 9bshow a schematic representation of a disc rotor in a second embodiment. Shown are a top view and a cross-section of the disc rotor. The rotor 13 is arranged within the stator 12 and its magnet 17 has an axial length L and a diameter D. The spinning ring 8 is fastened to the rotor 13. Rotor 13 and stator 12 are arranged concentrically around the axis of rotation 14. Four fastenings 18 are provided on the stator 12. The magnets 17 are shown schematically on the rotor 13, with a number of poles of six poles being evident in the top view. The stator 12 is provided with five teeth 34, each of which has a winding 24 attached, resulting in five strands.

[0037] The Figure 10shows a schematic representation of a disc rotor in a third embodiment in a plan view. The rotor 13 is arranged within the stator 12. Rotor 13 and stator 12 are arranged concentrically. Four fastenings 18 are provided on the stator 12. The magnets 17 are shown schematically on the rotor 13, with six poles being evident in the plan view. The stator 12 is provided with five teeth 34, resulting in five strands. The windings in the form of coils are attached to each of the teeth, with each inner coil on tooth 34 being designed as a radial force coil 32 and each outer coil on tooth 34 being designed as a torque coil 33. legend

[0038] 1Sliver 2Drafting system 3Thread 4Thread guide 5Yarn spool 6Twist of yarn spool 7Drive 8Spinning ring 9Ring frame 10Ring traveler 11Drive 12Stator 13Rotor 14Rotational axis of spinning ring 15Ring crown 16Connecting section 17Magnet 18Fastening 19Compensation means 20Emergency bearing 21Axial displacement sensor 22Radial displacement sensor 23Damping element 24Winding 25Rotational degree of freedom 26Axial degree of freedom 27Tilting degree of freedom 28Tilting degree of freedom 29Radial degree of freedom 30Radial degree of freedom 31Axial magnetic bearing 32Radial force coil 33Torque coil 34Stator tooth DRotor diameter LAxial length of rotor

Claims

1. Driven ring for a ring-spinning or ring-twisting machine, comprising an electric drive (11) having a stator (12) and a rotor (13) with a magnet (17), the ring comprising a ring crown (15), for a ring traveler (10) to be mounted on, and a connecting portion (16) and the ring being rotationally fixedly connected to the rotor (13) of the drive (11) via the connecting portion (16), characterized in that the drive (11) has a coil system for generating a torque and radial forces, one axial degree of freedom (26) and both tilting degrees of freedom (27, 28) of the rotor (13) being passively stabilized by reluctance forces, and both radial degrees of freedom (29, 30) being actively stabilized by a control loop.

2. Ring according to claim 1, characterized in that the drive is designed as a bearingless disc armature having a flat stator (12) and a ratio of an axial length (L) of the magnet (17) to a diameter (D) of the magnet (17) is less than 0.4.

3. Ring according to claim 1, characterized in that the drive is designed as a bearingless disc armature having a stator (12) in a temple construction, a ratio of an axial length (L) of the magnet (17) to a diameter (D) of the magnet (17) being less than 0.4.

4. Ring according to any of claims 1 to 3, characterized in that the ring traveler (10) is provided to be mounted in a free-moving manner on the ring crown (15).

5. Ring according to any of claims 1 to 3, characterized in that the ring traveler (10) is provided to be mounted on the ring crown (15) in a stationary manner.

6. Ring according to claim 5, characterized in that the ring traveler (10) and the ring crown (15) are formed in one piece.

7. Ring according to any of the preceding claims, characterized in that an additional active magnetic bearing (31) is provided for stabilizing the axial degrees of freedom (26) of the rotor (13).

8. Ring according to any of the preceding claims, characterized in that damping of the tilting vibrations is provided by a compensation means (19), the compensation means (19) having at least one electrical conductor loop separated from a winding.

9. Ring according to any of the preceding claims, characterized in that an emergency bearing (20) is provided, the emergency bearing (20) being formed by at least one sliding ring fastened to the stator (12).

10. Ring according to any of the preceding claims, characterized in that the magnet (17) of the rotor (13) has 6 poles and the stator (12) has 5 winding strands.

11. Ring according to any of claims 1 to 8, characterized in that the magnet (17) of the rotor (13) has 6 poles and the stator (12) has 4 to 6 winding strands.

12. Ring according to any of claims 1 to 8, characterized in that the magnet (17) of the rotor (13) has 4 poles and the stator (12) has 4 winding strands.

13. Ring-spinning machine having a ring rail (9) and at least one driven ring according to any of the preceding claims fastened to the ring rail (9).

14. Ring-spinning machine according to claim 13, characterized in that damping of a bearing of the driven ring is provided by a damping element (23) made of viscoelastic materials in a fastening means (18) of the stator (12) on the ring rail (9).

15. Ring-twisting machine having at least one driven ring according to any of claims 1 to 12.