GB2329477A

GB2329477A - Device on a draw frame for measuring a fibre sliver combination

Info

Publication number: GB2329477A
Application number: GB9820198A
Authority: GB
Inventors: Ferdinand Leifeld; Josef Temburg
Original assignee: Truetzschler GmbH and Co KG
Current assignee: Truetzschler GmbH and Co KG
Priority date: 1997-09-17
Filing date: 1998-09-16
Publication date: 1999-03-24
Anticipated expiration: 2018-09-16
Also published as: GB9820198D0; GB2329477B

Abstract

In a device on a draw frame for measuring the thickness of a fibre sliver combination, having a guide means (6, figure 1) for the slivers at the drawing system inlet, in which the slivers entering one next to the other are guided in one plane into and through a measuring means having a plurality of sensing elements 30. In order to facilitate considerably improved detection of the variations in thickness of the slivers and more accurate guiding of the slivers, each sensing element 30 is displaceably mounted and biased for displacement in the event of variations in the thickness of a respective sliver, the displacement of the individual sensing elements 30 being summed.

Description

Device on a draw frame for measuring a fibre sliver combination The invention relates to a device on a draw frame for measuring the thickness of fibre material, especially of a fibre sliver combination.

A device for measuring the thickness of a fibre sliver combination having a sliver guide means for guiding the slivers at the drawing system inlet is known in practice, in which the walls of the device are constructed to be at least partially tapered, causing the incoming slivers to converge in one plane, and downstream of which there is arranged a pair of rollers after which the slivers diverge again, the device having a loaded, displaceable scanning element which, together with a fixed countersurface, forms a constriction for the sliver combination passing through and a change in the position of which scanning element in the event of a variation in the thickness of the fibre sliver combination acts on a transducer device to produce a control pulse. The scanning element is associated with the sliver guide means, the slivers in the sliver guide means are condensed and scanned one next to the other in one plane, and the pair of rollers delivers the scanned slivers.

In the proposed arrangement, it has already been proposed to condense the slivers lying one next to the other over their width, from above. The scanning element is so configured that as well as performing the scanning movement, that is to say the condensing movement in the direction of the slivers, it is also able to perform a pivoting movement about an axis extending in the operating direction and thus takes account of the fact that slivers of different thicknesses may be arranged one next to the other. For that purpose the movable scanning element is associated with the slivers guided one next to the other and has a slide surface which presses the slivers against a fixed countersurface, thereby condensing them one next to the other. In that arrangement the thickest sliver determines the distance between the scanning element and the countersurface. Even a small thick area in a sliver will result in that distance being greater. The slivers to the right and left of that thick area are drawn, unmeasured, from the resulting gap without their thickness having been registered.

It is an aim of the invention to provide a device of the kind described at the beginning that avoids or mitigates the mentioned disadvantages, that facilitates, especially, considerably improved detection of fluctuations in the thickness of the slivers and allows more accurate guiding of the slivers.

The invention provides a device for measuring a parameter related to the thickness of a fibre sliver combination in a draw frame, the device including measuring means comprising a plurality of sensing elements, each sensing element being movably mounted and biased for displacement in response to variations in the thickness of a respective sliver, and the device further comprising summation means for summing the displacements of the individual sensing elements.

As a result of the measures taken according to the invention, the summation result can take account of the thickness or mass of a number of different slivers. Thus, by means of the possibility of measuring all the slivers individually in respect of their thickness (or mass) at the inlet to the draw frame, it is possible to obtain a differentiated result in which the individual thickness of the respective sliver can be taken into account. For the avoidance of doubt, references herein to a "respective sliver" are to be understood to extend to, say, two slivers, and are not to be construed as being limited to a single sliver. In that way adjustment for fluctuations in thickness of all the slivers is considerably improved, so that a more uniform draw frame sliver is obtained and consequently a better yarn is produced.

All the sensing elements may be connected to a pivotally mounted holding element which is biased by a force element and on which the summation result of the displacements of the individual sensing elements is present. Preferably, the sensing element is biased by a spring or the like. Advantageously, the sensing elements are formed by a leaf spring. Preferably, the leaf springs are attached at one end. Advantageously, the countersurface is the outer surface of a rotating roller.

The measuring element may be arranged upstream of the sliver guide means. The measuring element may be integrated into the sliver guide means. Preferably, the sensing elements are connected to a pivotally or displaceably mounted common holding element which is biased by a force element and on which the summation result of the displacements of the individual sensing elements is present, wherein the sensing elements comprise at one end a fastening region which is rigidly connected to the holding element, the sensing elements forming a steering element for the pivoting movement or displacement of the biased holding element, and the scanning region being formed by the other end of the sensing elements. Advantageously, the sensing element is a leaf spring. Preferably, the sensing elements rest against the end face of a feed table.

Advantageously, there is a space between the free end of the sensing elements and the free end of the feed table.

Preferably, the intake gap between feed table and feed roller in operation is substantially the same.

Advantageously, the feed table or the feed roller is spring-loaded, the springs being harder than the springs forming the sensing elements. Preferably, the feed table is mounted to be fixed in the direction of deflection of the sensing elements. Advantageously, the end of the sensing elements can be lifted away from the holding element. Preferably, there is a stop for the deflection of the sensing elements. Advantageously, the leaf springs are arranged parallel to one another. Preferably, the leaf springs are soft in the direction of displacement of the feed table. Advantageously, the leaf springs are rigid in the direction from the feed table to the holding element.

Preferably, the holding element is constructed in the form of a longitudinal bar. Advantageously, the holding element is arranged axially parallel to the roller. Preferably, the holding element is resistant to torsion.

Advantageously, at least one torsion rod is present on the holding element on the end face in the axial direction.

Preferably, the holding element is mounted in a pivot bearing on at least one end face. Advantageously, the holding element is associated with a measuring element for the pivoting movement. Preferably, the measuring element is an inductive displacement sensor. Advantageously, the measuring element comprises an inductive displacement sensor. Advantageously, the measuring element comprises strain gauges. Preferably, in a device in which any deviations in thickness are detected mechanically at several points over the width by the individual sensing elements, the deviations in thickness are combined by the common holding element by the formation of an aggregate value. Advantageously, the amount of fibre supplied for the draw frame is altered in accordance with the deviation of the actual value (average value) from a desired value.

Preferably, the sensing elements are arranged above the roller. Advantageously, the leaf springs project into the gap between the feed roller and another roller.

Preferably, the sensing elements are associated with at least one fixed stop element. Advantageously, the roller is mounted in fixed position. Preferably, the holding element consists of an extruded profile. Advantageously, the extruded profile is hollow inside. Preferably, the extruded profile is made of aluminium or an aluminium alloy. Advantageously, there is a shaft, for example a rod, bolt, peg or the like, on the holding element (39) on each end face in the axial direction.

Certain illustrative embodiments of invention will be described in more detail with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic side view of a regulated draw frame having a device according to the invention; Fig. 2a, 2b are a front view and a side view, respectively, of an embodiment having a number of sensing elements and a fixed countersurface; Fig. 3a, 3b are a perspective view (Fig. 3a) and a side view (Fig. 3b), respectively, of an embodiment having a number of sensing elements and a rotating countersurface; Fig. 4 shows an arrangement similar to Fig. 3 having a guide roller; Fig. 5 shows an arrangement similar to Fig. 3 having two transport rollers; and Fig. 6a, 6b are a plan view (Fig. 6a) and a sectional view (Fig. 6b), respectively, of an arrangement having a measuring element integrated into the sliver guide means.

With reference to Fig. 1, a draw frame 1, for example of the type made by Trützschler GmbH & Co. KG and known as the Trutzschler draw frame HSR, has a drawing system 2, upstream of which there is arranged a drawing system inlet 3 and downstream of which there is arranged a drawing system outlet 4. The slivers 5, coming from cans, enter the sliver guide means 6 and, drawn by the delivery rollers 7,8, are transported past the measuring element 9. The drawing system 2 is configured as a 4 over 3 drawing system, that is to say it consists of three lower rollers I, II, III (I output lower roller, II middle lower roller, III input lower roller) and four upper rollers 11, 12, 13, 14. In the drawing system 2, the drafting of the fibre bundle 5, which consists of several slivers, is carried out. The drafting operation is composed of the preliminary drafting operation and the main drafting operation. The roller pairs 14/III and 13/II form the preliminary drafting zone and the roller pairs 13/II and 11, 12/I form the main drafting zone. In the drawing system outlet 4 the drawn slivers 5 arrive at a web guide means 10 and are drawn by means of delivery rollers 15, 16 through a sliver funnel 17 in which they are combined to form a sliver 18, which is then laid in cans.

The delivery rollers 7, 8, the input lower roller III and the middle lower roller II, which are mechanically coupled together, for example by means of toothed belts, are driven by the regulating motor 19, it being possible to specify a desired value. (The associated upper rollers 14 and 13 rotate therewith.) The output lower roller I and the delivery rollers 15, 16 are driven by the main motor 20. The regulating motor 19 and the main motor 20 each has its own regulator 21 and 22, respectively. The regulation (speed regulation) is effected in each case by means of a closed regulating circuit, a tachogenerator 23 being associated with the regulator 19 and a tachogenerator 24 being associated with the main motor 20. At the drawing system inlet 3, a variable proportional to the mass, for example the cross-section of the incoming slivers 5, is measured by the inlet measuring element 9. At the drawing system outlet 4 the cross-section of the outgoing sliver 18 is obtained by an outlet measuring element 25 associated with the sliver funnel 17.

A central computer unit 26 (control and regulation device), for example a microcomputer having a microprocessor, transmits a setting for the desired value for the regulating motor 19 to the regulator 21. The measured values from the measuring element 9 are transmitted to the central computer unit 26 during the drawing operation. The measured values from the measuring element 9 and the desired value for the cross-section of the outgoing sliver 18 are used to determine in the central computer unit 26 the desired value for the regulating motor 19. The measured values from the outlet measuring unit 25 are used for the monitoring of the outgoing sliver 18 (output sliver monitoring). Using that regulating system it is possible to compensate for fluctuations in the crosssection of the incoming slivers 5, or to render the sliver 18 uniform, by appropriate regulation of the preliminary drafting operation.

In the embodiment of Fig. 2, a measuring device for measuring the thickness of the fibre slivers 5a to Sn comprises a number of scanning elements 30a to 30n arranged one next to the other over the width, the scanning elements being movable vertically in the direction of arrows B, C.

One end of each scanning element 30a to 30n is associated with a spring 31a to 31n, each spring being attached by its other end to a continuous fixed support element 32. Each scanning element is associated with a sensor 33a to 33n, for example an inductive displacement sensor, each of which converts the displacements of the scanning elements 30a to 30n into electrical signals which are supplied to a common electrical summation device 34. The sum signal 35 is used for regulation purposes (see Fig. 1 and 3b). Opposite the other end of the scanning elements 30a to 30n there is a continuous fixed sliding-contact element 36, for example a slide bar, the slivers 5a to Sn being moved through between the scanning elements 30a to 30n and the countersurface 36.

As may be seen from Fig. 2b, downstream of the measuring element 9 in the operating direction A there are arranged two driven rotating transport rollers 37, 38. In that manner all the slivers 5a to 5n are measured individually in respect of their width (or mass) at the inlet to the regulating zone. A sum signal 35 for the incoming sliver mass is formed therefrom.

Figs. 3a and 3b show a measuring device in which the scanning elements 30a to 30n are formed by a number of leaf springs (measuring plates), arranged one next to the other, which are each fixed by one end in a common summation holding element 39 (summation element), for example a summing bar, measuring lever or the like. The other (open) end of the leaf springs 30a to 30n presses against the slivers 5a to 5n. The mechanical summation element 39 is pivotally mounted at both ends in pivot bearings 40, 41 and loaded by a spring 42. Furthermore, the summing element 39 is associated with a sensor 43 which, as shown in Fig. 3b, supplies an electrical sum signal to a control device 44, downstream of which there is arranged a drive motor 45 for a roller 46. The roller 46, which extends over the width, rotates in direction F and forms a movable countersurface for the leaf springs 30a to 30n. Between the summing holding element 39 and the roller 46 there is a continuous feed table 47 which is rotatable about a bearing 48 and is loaded by a spring 49. The slivers 5 are drawn in through the gap between the roller 46 and the feed table 47. At the outlet of the gap, the slivers 5a to 5n are scanned in respect of their thickness by the leaf springs 30a to 30n, which can be deflected in the direction of arrows E and D.

This embodiment requires only one sensor 43.

In a further embodiment, shown in Fig. 4, the roller 46 is associated with a guide roller 50 which turns in direction G. It is used for guiding and transporting the slivers 5a to 5n.

Fig. 5 shows an embodiment in which the roller 46 is associated with a transport roller 37. The rollers 46, 37 rotate in the direction of arrows H and I, respectively.

The slivers 5 are transported through the nip between the rollers 46, 37. The leaf springs 30 extend into the nip between the rollers and press on the slivers 5 from above, the rotating surface of the roller 46 acting as countersurface.

Fig. 6a, 6b show an embodiment in which the measuring element 9 is integrated into the sliver guide means 6. The leaf springs 30a to 30n, which are affixed by one end to the summation element 39, each press with the other, open end on a sliver 5a to 5n. In accordance with this arrangement it is possible to scan a varying number of slivers 5a to 5n, for example only six slivers instead of the eight shown. The side walls 6a, 6b cause the slivers to converge at the sides, that is to say the fibre bundle is condensed at the side irrespective of the number of slivers 5a to 5n. Each sliver 5a to 5n can be assigned a scanning element 30a to 30n, so that individual measurement is possible. It is also possible, however, for a sliver 5 to be associated with more than one scanning element 30 (of a number of scanning elements 30a to 30n). Also possible is an arrangement in which a scanning element 30 (of a number of scanning elements 30a to 30n) is associated with more than one sliver. The summing element 39 provides in each case for a summation of the deflections of the scanning elements 30a to 30n. In that way, a differentiated summation result is obtained.

Claims

Claims:

1. A device for measuring a parameter related to the thickness of a fibre sliver combination in a draw frame, the device including measuring means comprising a plurality of sensing elements, each sensing element being movably mounted and biased for displacement in response to variations in the thickness of a respective sliver, and the device further comprising summation means for summing the displacements of the individual sensing elements.

2. A device according to claim 1, wherein the sensing elements are connected to a common pivotally mounted holding element which is biased by a force element and on which the summation result of the displacements of the individual sensing elements is present.

3. A device according to claim 2, wherein each sensing element is biased by a spring or the like.

4. A device according to any one of claims 1 to 3, wherein each sensing element is formed by a leaf spring.

5. A device according to claim 4, wherein the leaf springs are affixed at one end.

6. A device according to any one of claims 1 to 5, which comprises a countersurface which, together with the sensing elements, forms a constriction through which in use the combination passes.

7. A device according to claim 6, wherein the countersurface is the outer surface of a rotating roller.

8. A device according to any one of claims 1 to 7, which comprises a guide means for the slivers, the guide means being arranged to guide the slivers in one plane into and through the measuring means.

9. A device according to claim 8, wherein the measuring means is arranged upstream of the sliver guide means.

10. A device according to claim 8, wherein the measuring element is integrated into the sliver guide means.

11. A device according to any one of claims 1 to 10, in which the sensing elements are connected to a pivotally or displaceably mounted common holding element which is biased by a force element and on which the summation result of the displacements of the individual sensing elements is present, and wherein the sensing elements comprise at one end a fastening region which is rigidly connected to the holding element, the sensing elements forming a steering element for the pivoting movement or displacement of the biased holding element, and the scanning region being formed by the other ends of the sensing elements.

12. A device according to claim 11, wherein the sensing elements rest against the end face of a feed table.

13. A device according to claim 12, wherein there is a space between the free ends of the sensing elements and the free end of the feed table.

14. A device according to claim 12 or claim 13, wherein an intake gap for fibre material is formed between the feed table and a feed roller the intake gap remaining substantially unchanged in operation.

15. A device according to claim 14, wherein the feed table and/or the feed roller is spring-loaded, the springs being more rigid than springs that provide the biasing of the sensing elements.

16. A device according to any one of claims 12 to 15, wherein the feed table is mounted to be fixed in the direction of deflection of the sensing elements.

17. A device according to any one of claims 12 to 16, wherein the sensing elements are leaf springs which are arranged parallel to one another.

18. A device according to claim 17, wherein the leaf springs are soft in the direction of displacement of the feed table.

19. A device according to claim 17 or claim 18, wherein the leaf springs are rigid in the direction from the tray to the holding element.

20. A device according to any one of claims 17 to 19, which comprises a feed roller for the fibre material, the holding element being arranged axially parallel to the roller.

21. A device according to claim 20, wherein the sensing elements are arranged above the roller.

22. A device according to claim 19 or claim 20, wherein the sensing elements are leaf springs which project into the gap between the feed roller and a further roller.

23. A device according to any one of claims 20 to 22, wherein the roller is mounted in fixed position.

24. A device according to any one of claims 17 to 23, wherein the holding element is constructed in the form of a longitudinal bar.

25. A device according to any one of claims 17 to 24, wherein the holding element is resistant to torsion.

26. A device according to any one of claims 12 to 25, wherein at least one torsion rod is present on the holding element on an end face in the axial direction.

27. A device according to any one of claims 12 to 26, wherein the holding element is mounted in a pivot bearing on at least one end face.

28. A device according to claim 27, wherein the holding element is associated with a measuring element for the pivoting movement.

29. A device according to claim 28, wherein the measuring element is an inductive displacement sensor.

30. A device according to claim 18, wherein the measuring element comprises strain gauges.

31. A device according to any one of claims 12 to 30, wherein the holding element consists of an extruded profile.

32. A device according to claim 31, wherein the extruded profile is hollow inside.

33. A device according to claim 31 or claim 32, wherein the extruded profile is made of aluminium or an aluminium alloy.

34. A device according to any one of claims 12 to 33, wherein there is a shaft, for example a rod, peg or the like, on the holding element on each end face in the axial direction.

35. A device according to claim 2 or to any one of claims 3 to 10 when dependent on claim 2, wherein the end of the sensing elements can be lifted away from the holding element.

36. A device according to claim 35, wherein there is a stop for the deflection of the sensing elements.

37. A device according to any one of claims 1 to 36, which is arranged to detect mechanically the thickness at several points over the width by the individual sensing elements, wherein the deviations in thickness are summed by the common holding element by the formation of an average value.

38. A device according to any one of claims 1 to 37, which is arranged to generate a signal representative of the summed deviations, which signal can be used to control the amount of fibre supplied for the draw frame in accordance with the deviation of the actual value (average value) from a desired value.

39. A device on a draw frame for measuring the thickness of a bundle of slivers, having a guide means for the slivers at the drawing system inlet, in which the slivers entering one next to the other are guided in one plane into and through a measuring element and in which there is a loaded, displaceable scanning element which, together with a countersurface, forms a constriction for the bundle of slivers passing through, thereby condensing the bundle of slivers, and a change in the position of which sensing element in the event of a variation in the thickness of the fibre bundle acts on a transducer device to produce a control pulse, characterised in that the scanning element has a number of sensing elements and each sensing element is displaceably mounted and biased for displacement in the event of variations in the thickness of a respective sliver, the displacements of the individual sensing elements being summed.

40. A device for measuring a fibre sliver combination in a draw frame, the device being substantially as described herein with reference to and as illustrated by any of Figs. 1, 2a and 2b, 3a and 3b, 4, 5, and 6a and 6b.