GB2501387A

GB2501387A - A device for drafting fibre slivers more evenly by means of self-adjusting the lap spacing between rollers

Info

Publication number: GB2501387A
Application number: GB1305694.0A
Authority: GB
Inventors: Britta Lustraeten
Original assignee: Truetzschler GmbH and Co KG
Current assignee: Truetzschler GmbH and Co KG
Priority date: 2012-04-20
Filing date: 2013-03-28
Publication date: 2013-10-23
Also published as: BR102013009563B1; DE102012007777A1; BR102013009563B8; ITMI20130198A1; CH706406A2; CN103374773B; CH706406B1; BR102013009563A2; CN103374773A; GB201305694D0

Abstract

A device on a drafting mechanism of a spinning room machine, for drafting one or more fibre slivers, comprising at least two roll pairs arranged one after another. The upper rolls are arranged to be pressed against the lower rolls by spring loading. At least one cylinder containing a piston 18 is arranged so as to be axially movable within the cylinder housing 9, from which a piston rod 19 extends towards the upper roll. A sensor arrangement 24, 25 is provided for determining the position of the piston, with a switching element connected to the piston. To allow self-adjusting lap recognition with a desired spacing of the switching element from the switch, there is arranged, between the switching element and the piston, a magneto rheological substance, such as a magnetorheological elastomer (MRE) 26, or fluid, which co-operates with an electromagnetic coil 27. The MRE is able to modify its viscoelastic properties when exposed to the field of the coil, which, when activated, hardens the MRE. If a lap starts to form around the rolls, the piston 18 presses against the MRE 26, which in turn presses the switching screw 25 upwards, triggering the sensor.

Description

Device on a drafting mechanism of a spinning room preparation machine, especially a draw frame, carding machine, combing machine, lap winder or the like The invention relates to a device on a drafting mechanism of a spinning room machine, especially a draw frame, carding machine, combing machine, lap winder or the like, for drafting one or more fibre slivers.

It is known in a drafting mechanism to have at least two roll pairs arranged one after another, the upper rolls of which are arranged to be pressed against the lower rolls by loading means, and to have at least one cylinder having a piston which can be subjected to loading and relieved of loading and which is arranged so as to be axially movable within a cylinder housing, from which piston a piston rod extends towards the upper roll, there being provided a sensor arrangement for determining the position of the piston having the piston rod, in which on the side remote from the piston rod a switching element is connected to the piston.

In a known device (EP 1 428 914 A) a switching disk is mounted on the piston rod slidably and coaxially with the piston, in frictional engagement, which disk co-operates with a switch for determining the position of the piston.

The switching disk is at least partially permanently magnetic in order to co-operate with an inductive sensor as a switch for determining the position of the piston. If a lap of fibre material then forms around the upper roll, the upper roll, which is floating in respect of its mounting, is pushed in the direction of the pressure medium cylinder.

As a conseguence thereof, the pressure rod of the pressure medium cylinder, which rod contacts the upper roil, moves in the direction of the retracted end position. On retraotion of the pressure rod, the switching disk mounted thereon in frictional engagement through-connects the switch, and the drafting mechanism is switched off. The drafting mechanism then has to be opened manually and the iap removed. The drafting mechanism then has to be brought back into the operating position by closing the loading arm.

When a pressure medium cylinder (pneumatic cylinder) is used, the loading force on the upper rolls is generated when the piston is extended outwards. On extending outwards, the switching disk is likewise moved against an end-stop, that is to say it is brought into a defined position. Tf a lap forms around a roll, the piston is pressed in the opposite direction, and the lap is recognised by the proximity switch as a result of the movement of the switching disk. As a result of the defined end-stop, lap recognition is independent of the outer diameter of the upper rolls. It does not need to be re-adjusted after polishing of the rolls. Spring-loading cannot be used in the case of this device. Tf spring-loading were used, the loading force of the upper rolls would be applied as a result of the biasing of the spring.

This can be accomplished in combination with locking of the drafting mechanism top unit. In this case, however, the piston is pushed into the cylinder on application of the loading force (biasing of the spring) and, in the event of a lap, is moved in the same direction. It is therefore not possible for the switching disk to be moved up against an end-stop in the known manner in order to produce a defined spacing of the switching disk from the proximity switch.

It is an aim of the invention to provide a device of the kind described at the beginning which avoids or mitigates the mentioned disadvantages and which especially enables self-adjusting lap recognition and allows a desired spacing of the switching element from the switch.

The invention provides a device on a drafting mechanism of a spinning room machine for drafting one or more fibre slivers, having at least two roll pairs arranged one after another, the upper rolls of which are arranged to be pressed against the lower rolls by loading means, having at least one cylinder comprising a cylinder housing and a piston which can be subjected to loading and relieved of loading and which is arranged so as to be axially movable within the cylinder housing, from which piston a piston rod extends towards the upper roll, there being provided a sensor arrangement for determining the position of the piston, wherein on the side of the piston remote from the piston rod a switching element is connected to the piston, wherein between an end of the switching element and the piston there is arranged a magnetorheological substance, which co-operates with an electromagnetic coil, and the loading means is a spring. As a result of the use, according to the invention, of a magnetorheological substance, especially an elastomer, there is provided a spacing-independent coupling. In this way it is possibie to use a spring as loading element. A particular advantage lies in self-adjusting lap recognition.

Advantageously, the loading means is a compression spring. Advantageously, the magnetorheological substance is a magnetorheological elastomer. Advantageously, the magnetorheological substance is a magnetorheological fiuid (liguid) In one preferred embodiment, a spring element, for example a compression spring, supports the switching element force-loaded against a cylinder surface.

Advantageously, the sensor arrangement is an inductive proximity switch. Advantageously, the sensor arrangement consists of a switching element and counterpart element.

Advantageously, the switohing arrangement consists of a switching element and switch. Advantageously, the sensor arrangement comprises a spacing sensor and a counterpart element. Advantageously, the sensor arrangement is an inductive displacement transducer. Advantageously, the switching element is a bolt or the like. Advantageously, the switching element passes through a oylinder top bounding the end of the cylinder housing. Advantageously, the sensor arrangement is arranged outside the cylinder.

Advantageously, the sensor arrangement is integrated inside in the cylinder housing. Advantageously, the device is used for identifying laps. Advantageously, the sensor arrangement is connected to an electrical evaluation device.

Advantageously, where the sensor arrangement comprises a proximity switch, the proximity switch senses the spacings from an end face of the switching element (counterpart element) . Preferably, the proximity switch is immobile and the switching element (counterpart element) is movable relative to the proximity switch. In some embodiments, the spacing measuring means is a light sensor.

By way of example, the spacing measuring means may be a laser sensor. Advantageously, the sensor arrangement is connected to a switching-off device for the drafting mechanism. Advantageously, the sensor arrangement is connected to a load-relieving device for the upper rolls.

Advantageously, the magnetorheological element forms a coupling. Advantageously, the coupling is used for self-adjusting lap recognition. Advantageously, the sensor arrangement is a contact switch.

Certain illustrative embodiments of the invention will be described hereinafter in greater detail with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic side view of the drafting mechanism of a draw frame having the device according to the invention; Fig. 2 shows part of Fig. 1 in a section according to K-K (Fig. 1) having a spring-loaded upper roll loading device; and Fig. 3 is a section through a cylinder according to the invention (loading cylinder) having a spacing-independent coupling.

Fig. 1 shows a drafting mechanism S of a draw frame. The drafting mechanism S is configured as a 4-over-3 drafting mechanism, that is to say it consists of three lower rolls I, II, III (I output lower roll, II middle lower roll, III input lower roll) and four upper rolls 1, 2, 3, 4. The drafting of the fibre bundle 5, which consists of a plurality of fibre slivers, is carried out in the drafting mechanism S. The drafting operation is composed of the preliminary drafting operation and the main drafting operation. The roll pairs 4/Ill and 3/Il form the preliminary drafting zone and the roll pairs 3/Il and 1,2/I form the main drafting zone. The output lower roll I is driven by the main motor (not shown) and thus determines the delivery speed. The input and middle lower rolls III and II are driven by a regulating motor (not shown) . The upper rolls 1 to 4 are pressed against the lower rolls I, II, III by pressure elements 9 to 94 (loading device) in presser arms (not shown), which are pivotable about pivot mountings 10 (see Fig. 2), and are thus driven by frictional engagement. The directions of rotation of the rolls I, II, III; 1, 2, 3, 4 are indicated by curved arrows. The fibre bundle 5, which consists of a plurality of slivers, runs in direction A. The lower rolls I, II, III are mounted in supports 14 (see Fig. 2) which are arranged on the machine frame 15.

With reference to Fig. 2, the bottom of the spring-loaded pressure cylinder 9 is associated with a holding element 13. The pressure cylinder 9 forms a cylinder unit having a cylinder cavity 17 comprising two parts 17a and 17b (see Fig. 3), in which cavity a piston 18 is guided in a slide bush 20 by means of a pressure rod 19. The neck 4 of the upper roll 4 passes through an opening in a holding bracket 21 and into a mounting 22. The mounting 22 accommodating the upper roll 4 extends into a space between the pressure rod 19 and the neck lila of the lower roll III. The mounting 22 is mounted, by way of a projection 23, on the holding element 13.

In operation, after a fibre bundle 5 has been guided over the lower rolls I, II, III, the presser arms are pivoted into the working position and fixed in that position by a fixing device (not shown) , so that the pressing rolls I, II, III are able to exert contact pressure. This contact pressure is produced, on the one hand, by means of the fact that the pressure rods 19 in each case rest on the corresponding mounting 22 and, on the other hand, by the compression spring 16 (see Fig. 3) exerting pressure. As a result, the end of the pressure rod 19 presses on the mounting 22 in order to produce the mentioned contact pressure between the upper roll 4 and the lower roll (drive roll) ITT. The pressure rod 19 (piston rod) is movable in the direction of arrows 5, B. Reference numeral 10 denotes a pivot mounting, around the point of rotation of which the holding element 13 can be pivoted in the direction of arrows B, C. In an illustrative embodiment shown in Fig. 3, the pressure cylinder 9 is arranged in the drafting mechanism top unit (not shown) and, on looking of the top, is drawn down in the direction of the upper roll mounting 22. In the process, the desired loading force is exerted on the rolls 1, 2, 3, 4 by means of a spring 16. The piston 18 is, in this case, pushed into the cylinder to a different extent depending on the diameter of the upper rolls 1, 2, 3, 4. A proximity switch 24 is arranged above the cylinder. The switch detects the position of a switching sorew 25. The latter is brought into a defined position by means of a spring 26. Between the switching screw 25 and the piston 18 there is arranged a magnetorheological elastomer 26, abbreviated to MRE, as a coupling. This is an elastomer which includes magnetic partioles (in the main, iron) and which has the property of modifying its viscoelastic properties under the influence of a magnetic field. In the normal state it accordingly has a rather ITielly_likelT consistency and becomes hard when it is exposed to the magnetic field of a coil 27. This means that the MRE 26, in the case of biasing by the spring, is not exposed to a magnetic field, and the piston 18 presses against the still soft elastomer 26. The contour of the MRE adapts to the movement of the piston, independently of the depth of insertion of the latter. When operation of the drafting mechanism is started, a magnetic field is generated by the coil 27, and the MRE 26 changes its consistency and becomes harder. Tn this context, the magnetic field needs only to be of sufficient magnitude for the spring force of the relatively hard elastomer to be greater than the spring force of the upper spring 28. If a lap starts to form around the rolls, the piston 18 presses against the MRF 26 and the latter presses the switching screw 25 upwards. The proximity switch 24 recognises the 1ap and triggers, for example, a display, relief of loading, or the like.

The cylinder cavity 17 (interior) of the cylinder 9 has, on its internal wall surface (side wall) , a circular annular projection 9', which divides the cylinder cavity 17 into two parts 17a and 17b. The magnetorheological elastomer 26, the spring 28 (for example, compression spring), part of the switching screw 25 and a shoulder 18' on the piston 18 are located in part 17a. The compression spring 16 and part of the piston 18 including a shoulder 18' on the piston 18 are located in part 17b. The compression spring 16 is supported at one end against the projection 9' and at the other end against the shoulder 18'' . The piston 18 passes through the circular opening in the projection 9'. The compression spring 28 is supported at one end against a shoulder 25' on the switching screw 25 and at the other end against the internal surface of the top wall 17' (cylinder top) of the cylinder 9. The switching screw 25 passes through a circular opening in the top wall 17'.

The invention has been illustrated using the example of a magnetorheological elastomer. The invention also encompasses a magnetorheological liquid. This is a suspension of oils and magnetic particles, which has similar properties to the elastomer, that is to say it changes its viscosity under the influence of a magnetic

field.

The coupling according to the invention can not only be used for self-adjusting lap recognition but also has a place in other applications.

List of reference numerals 24 proximity switch switching screw 28 spring for defined abutment of the switching screw 27 coil (electromagnet) 26 magnetorheological elastomer (MRE) 18 piston 16 spring for loading of the upper rolls 22 upper roll mounting

Claims

-10 -Claims 1. A device on a drafting mechanism of a spinning room machine for drafting one or more fibre slivers, having at least two roll pairs arranged one after another, the upper rolls of which are arranged to be pressed against the tower rolls by loading means, having at least one cylinder comprising a cylinder housing and a piston which can be subjected to loading and relieved of loading and which is arranged so as to be axially movable within the cylinder housing, from which piston a piston rod extends towards the upper roll, there being provided a sensor arrangement for determining the position of the piston, wherein on the side of the piston remote from the piston rod a switching element is connected to the piston, wherein between an end of the switching element and the piston there is arranged a magnetorheological substance, which co-operates with an electromagnetic coil, and the loading means is a spring.
2. A device according to claim 1, wherein the loading means is a compression spring.
3. A device according to claim 1 or claim 2, wherein the magnetorheological substance is a magnetorheological elastomer.
4. A device according to any one of claims 1 to 3, wherein the magnetorheological substance is a magnetorheological fluid.
5. A device according to any one of claims 1 to 4, wherein the switching element is supported by a spring element that is force-loaded against a surface of the cylinder housing.

-11 -
6. A device according to any one of claims 1 to 5, wherein the sensor arrangement is an inductive proximity switch.
7. A device according to claim 6, wherein the proximity switch senses the spacings from the end face of the switching element.
8. A device according to claim 6 or claim 7, wherein the proximity switch is immobile and the switching element is movable relative to the proximity switch.
9. A device according to any one of claims 1 to 8, wherein the sensor arrangement comprises a switching element and counterpart element.
10. A device according to any one of claims 1 to 9, wherein the switching arrangement comprises a switching element and switch.
11. A device according to any one of claims 1 to 10, wherein the sensor arrangement comprises a spacing sensor and a counterpart element.
12. A device according to any one of claims 1 to 11, wherein the sensor arrangement is an inductive displacement transducer.
13. A device according to any one of claims 1 to 12, wherein the switching element is an elongate member.
14. A device according to any one of claims 1 to 13, wherein the switching element extends through a top wail of the cylinder bounding the end of the cylinder housing.
15. A device according to any one of claims 1 to 13, wherein the sensor arrangement is arranged outside the cylinder.
16. A device according to any one of claims 1 to 13, wherein the sensor arrangement is integrated inside in the cylinder housing.

-12 -
17. A device according to any one of claims 1 to 16, wherein the device is usable for identifying laps.
18. A device according to any one of claims 1 to 17, wherein the sensor arrangement is connected to an electrical evaluation device.
19. A device according to any one of claims 1 to 18, wherein the spacing measuring means is a light sensor.
20. A device according to any one of claims 1 to 19, wherein the spacing measuring means is a laser sensor.
21. A device according to any one of claims 1 to 20, wherein the sensor arrangement is connected to a switching-off device for the drafting mechanism.
22. A device according to any one of claims 1 to 21, wherein the sensor arrangement is connected to a load-relieving device for the upper rolls.
23. A device according to any one of claims 1 to 22, wherein the magnetorheological element forms a coupling.
24. A device according to claim 23, wherein the coupling is usable for self-adjusting lap recognition.
25. A device according to any one of claims 1 to 24, wherein the sensor arrangement comprises a contact switch.
26. A device on a drafting mechanism of a spinning room machine, especially a draw frame, carding machine, combing machine, lap winder or the like, for drafting one or more fibre slivers, having at least two roll pairs arranged one after another, the upper rolls of which are arranged to be pressed against the lower rolls by loading means, having at least one cylinder having a piston which can be subjected to loading and relieved of loading and which is arranged so as to be axially movable within a cylinder housing, from which piston a piston rod extends towards the upper roil, there being provided a sensor arrangement for determining -13 -the position of the piston having the piston rod, wherein on the side remote from the piston rod a switohing element is connected to the piston, wherein between one end of the switching element and the piston there is arranged a magnetorheological substance, which co-operates with an electromagnetic coil, and the loading means is a spring, for example a pressure spring.
27. A drafting system comprising a device according to any one of the preceding claims.
28. A sensor arrangement substantially as described herein with reference to and as illustrated by any one of Figs. 1 to 3.