GB2058157A - Mounting friction disc spindles - Google Patents

Abstract

A friction false twister for use in crimping synthetic filaments comprises a base plate (1) and shafts e.g. (5, 6) cantilever-mounted thereon at the corners of a polygon. Friction discs are clamped onto the shafts so as to overlap each other in the central region of the polygon and there define a zig-zag shaped filament path. Each shaft is mounted in a bearing- receiving opening of the base plate (1), in two rolling bearings (26, 27). The lower bearing (26) further from the friction discs is radially fixed with respect to the bearing-receiving opening. The upper bearing (27) nearer the friction discs is mounted with the insertion of a radial damping element (29, 30). <IMAGE>

Description

SPECIFICATION Friction false twister This invention relates to a friction false twister for use in crimping synthetic filaments, comprising a base plate having a plurality of shafts mounted thereon at the corners of a polygon, the shafts having friction discs mounted thereon which overlap one another and define a zig-zag shaped filament path. Such friction false twisters are known, for example, from German Patent P 2213881.

Friction false twisters of this type are used so as to meet the increasing filament run velocity during the processing of synthetic fibres. However, problems of stability and in particular of vibration arise with the increase in speed of the friction false twisters.

An object of the invention is to provide a friction false twister in which the problems of stability and vibration are avoided or reduced. It has been found here that an increase in strength characteristics cannot overcome the stability and vibration problems which occur. What is provided according to the invention is a friction false twister for use in crimping synthetic filaments, comprising a base plate and a plurality of shafts cantilever mounted thereon at the corners of a polygon, the shafts being provided with friction discs which overlap each other in the central region of the polygon and there define a zig-zag shaped filament path, wherein each shaft is mounted in a bearing-receiving opening of the base plate in two rolling bearings, the bearing further from the friction discs being radially fixed with respect to the bearing-receiving bearing, and the bearing nearer the friction discs being mounted with the insertion of a radial damping element. The lower bearing is preferably also designed as a bearing which is fixed in an axial direction.

The axial bearing clearance of both bearings may be reduced by spring-bracing outer rings of the rolling bearings against each other in an axial direction.

In one embodiment, which has the particular advantage that it uses rolling bearings which are conventional in trade, the rolling bearings are each mounted in a respective bush and are fitted into a bearing-receiving opening. The bush in which is located the lower rolling bearing fits closely, axially and radially into the bearing-receiving opening and is secured therein. The other bush in which is located the upper rolling bearing is introduced into the bearing-receiving opening with a small clearance of, for example, 0.2 mm and is mounted in damping elements, e.g. rubber rings with respect to the bearing-receiving opening. The upper and lower bushes are spring-braced against each other. A mounting of this type may also be installed in existing friction false twisters.

Another embodiment which particularly allows the use of thin base plates provides that the upper and lower rolling bearings are housed in a single bush. This bush may be securely clamped radially and axially in the bearing-receiving opening of the base plate. The ball grooves of the lower bearing are ground on one side into the respective shaft and into the bush on the other side so that this lower bearing constitutes a fixed bearing. The ball grooves of the upper bearing are ground on one side into the respective shaft and into an outer ring on the other side. This outer ring is fitted into the bush with a clearance (e.g. 0.2 mm) and is mounted in damping elements (e.g. rubber rings) with respect to the bush. The upper bearing is therefore a movable bearing.In order to avoid the radial clearance of the lower bearing, the outer ring of the upper bearing is spring-braced in an axial direction with respect to the bush.

The invention further provides a mounting for a vertical, cantilever-mounted shaft, comprising a lower fixed bearing and an upper movable bearing, particularly for mounting shafts of friction false twisters comprising three or more shafts which are mounted rotatably and vertically in a base plate and friction discs mounted thereupon, wherein the mounting comprises a single bush which may be received in an opening a groove of the lower bearing is ground into the bush on one side and into the shaft on the other side, a groove 10 for the upper movable bearing is ground into the shaft on one side and into an outer ring on the other side, and an outer bearing ring is guided in an axially movable manner in the bush.

The mounting used in the present invention provides for low-vibration operation of the friction false twister. Such friction false twisters have a broad operational speed range according to the purpose of use. Experiments have shown that with the mounting used in the invention, in a broad speed range of from 3,000 to 20,000 r/min, there were no substantial vibrations and in particular no resonance vibrations at critical speeds. When the friction false twister was started up, no critical speed ranges were observed.

In the accompanying drawings: Figure 1 shows a top view of a friction false twister to clarify the geometric arrangement of the shafts at the corners of a polygon: Figure 2 is an elevation of one embodiment of the invention; Figure 3 is an elevation of another embodiment of the invention; and Figures 3a and 3b show details of the mounting according to Figure 3.

Figure 1 shows three rotatably mounted shafts are positioned in the corners of a polygon, though there may be more than three shafts. Friction discs are braced in an axial direction on the shafts.

These friction discs overlap each other in the central region of the polygon, so that a filament is guided in a direction generally parallel to the shafts in a zig-zag manner around the outer edges of the friction discs.

Figures 2 and 3 show primarily the mountings used in the invention, the remaining parts of the friction false twister being roughly omitted as they are not relevant to the invention.

In Figure 2, the friction discs are attached to the shafts 5 and 6 and are braced axially against a flange 18 by a screw 8 and a plate spring 17. The shaft 5 is mounted in rolling bearings 26, 27 in a base plate 1. The lower bearing 26 is designed as a fixed bearing and sits in a bush 3. The bush 3 sits with a close fit in a bearing-receiving opening of the base plate 1. A resilient fit element 28 provides for clearance-free accommodation of the bush 3 in the bearing-receiving opening.

The upper rolling bearing 27 is mounted in a second bush 2 as a movable bearing. For this purpose, the bush 2 is guided with a small clearance of a few tenths mm with respect to the bearing-receiving opening. Resilient elements 29, 30, for example rubber rings, bridge this clearance. Sealing rings 31 prevent impurities from penetrating into the mountings.

The bushes 2 and 3 are braced axially against each other by a plate spring 32, whereby the bushes 2 and 3 rest against the outer ring of the rolling bearings 26, 27 in the direction of the resilient force. By these measures, the outer rings of the rolling bearings are braced against each other, so that the axial bearing clearance is reduced. The inner rings of the rolling bearings 26, 27 are spaced apart by a sleeve 33 and are secured axially.

In the embodiment of Figure 3, only one bearing bush 4 is used which is fitted without a clearance into the base plate 1 by a fitting element 20 (Figure 3b). Ball grooves 9 of the lower ball bearing 14 are ground on one side into the shaft 5 (or 6 or 7 respectively) and into the bearing bush 4 on the other side. This is therefore a fixed bearing.

The inner ball groove 10 of the upper ball bearing 11 is ground into the shaft 5 or 6, 7 respectively. The outer ball groove is located, however, in an outer ring 1 3. The outer ring 13 is mounted in a damping element 12, e.g. a rubber ring or an O-ring, with a clearance with respect to the bearing bush 4. It should be mentioned that in Figure 3, the left and right halves of the illustration show different embodiments of the outer ring 1 3.

The outer ring 1 3 in the right half of the drawing has an annual groove in its outer circumference, into which the damping element 12 is partially received.

The outer ring 13 of the upper ball bearing 11 is braced axially by plate springs 1 6 with respect to the flange 15 of the bearing bush 4, which again results in the axial bearing clearance of the total mounting being reduced. Sealing rings 24 and 25 are provided.

The bearing bush 4 is pressed against the base plate 1 by a clamping plate 22 and a screw 23, shown on a reduced scale in Figure 3a. The clamping plate 22 comprises recesses 1 9 so that when the clamping plate 22 is turned, the bearing bush may be drawn by its flange 21 out of the bearing-receiving opening of the base plate 1.

Figure 3b shows the cross section of the fitting element 20 before installation. By using this element, it is possibie to use a loose fit or a sliding fit for the bearing-receiving opening and bush 4 and to ensure nevertheless a clearance-free mounting of the bush 4 in the bearing-receiving opening of the base plate 1.

When the expression "rigidly mounted" is used herein it is to be understood as meaning mounted without clearance.

Claims (17)

1. A friction false twister for use in cromping synthetic filaments, comprising a base plate and a plurality of shafts cantilever mounted thereon at the corners of a polygon, the shafts being provided with friction discs which overlap each other in the central region of the polygon and there define a zig-zag shaped filament path, wherein each shaft is mounted in a bearing-receiving opening of the base plate in two rolling bearings, the bearing further from the friction discs being radially fixed with respect to the bearing-receiving bearing, and the bearing nearer the friction discs being mounted with the insertion of a radial damping element.

2. A friction false twister according to claim 1, wherein the axial bearing clearance of the rolling bearings is reduced by an axial bracing of the bearings.

3. A friction false twister according to claim 2, wherein the said axial bracing is resilient in nature.

4. A friction false twister according to claim 3, wherein the second mentioned bearing is movable bearing with respect to its outer ring, the said outer ring being spring braced with respect to the outer ring of the first mentioned bearing, and the first mentioned bearing being a fixed bearing.

5. A friction false twister according to claim 1, wherein the bearings are each mounted in a respective bush, the bush of the first mentioned bearing being radially fixed in the bearingreceiving opening of the base plate, and the bush of the second mentioned bearing being mounted in the bearing-receiving opening of the base plate with a radial clearance with the insertion of the said damping element.

6. A friction false twister according to claim 5, wherein the bushes are supported respectively against the outer rings of their rolling bearings and are spring braced against each other, the inner rings of the rolling bearing being secured axially on the shaft.

7. A friction false twister according to claim 1, wherein the bearings are mounted in a common bush which axially and radially fixed in the bearing-receiving opening of the base plate, the second mentioned bearing having an outer ring which is supported by a damping element with respect to the bush.

8. A friction false twister according to claim 7, wherein the second mentioned bearing is a movable bearing, the first mentioned bearing is a fixed bearing, and the outer ring of the second mentioned bearing is resiliently supported with respect to the bush in an axial direction.

9. A friction false twister according to claim 7 or 8, wherein the outer ring of the second mentioned bearing has an annular groove in its circumference in which the damping element is partially received, the projecting part of the damping element bearing against the bush.

10. A friction false twister according to any preceding claim, wherein the bush has a flange by which it rests against the base plate and a screw thread which makes a screw connection with the base plate.

11. A friction false twister according to any one of claims 1 to 9, wherein the bush has a flange by which it rests against the base plate, and a pressure plate is positioned on the base plate by a screw connection, which pressure plate presses the flange against the base plate.

12. A friction false twister according to claim 11 , wherein the pressure plate has recesses which correspond to the outer circumference of the flange of the bush such that when the pressure plate is rotated it either presses the bush against the base plate or permits axial movement of the bush.

13. A friction false twister substantially as herein described with reference to Figures 1 and 2, or Figures 1, 3, 3a and 3b of the accompanying drawings.

14. A mounting for a vertical, cantilevermounted shaft, comprising a lower fixed bearing and an upper movable bearing, particularly for mounting shafts of friction false twisters comprising three or more shafts which are mounted rotatably and vertically in a base plate and friction discs mounted thereupon, wherein the mounting comprises a single bush which may be received in an opening, a groove of the lower bearing is ground into the bush on one side and into the shaft on the other side, a groove 10 for the upper movable bearing is ground into the shaft on one side and into an outer ring on the other side, and an outer bearing ring is guided in an axially movable manner in the bush.

1 5. A mounting according to claim 14, wherein the outer ring is supported by a resilient element with respect to the bush.

16. A mounting according to claim 15, wherein the resilient element is a rubber ring.

17. A mounting according to claim 15 or 16, wherein the bush is braced by a spring in an axial direction with respect to the outer ring.