GB2305980A - Bearing assembly - Google Patents

Description

2305980 BEMING ASSEMBLY This invention relates to a bearing assembly.

In accordance with the present invention there is provided the use of a bearing assembly to support andlor receive andlor guide a linear textile article, the bearing assembly being mounted in use on a support,.the assembly comprising an inner rotatable annulus which is free to rotate about the support and an outer rotatable annulus which is free to rotate about the inner annulus, the linear textile article being in contact with the outer annulus.

Suitably there are friction-reducing means between the inner annulus and the outer annulus. Suitably there are rolling elements, for example spherical balls or cylindrical rollers. therebetween. The outer annulus preferably runs directly about the inner annulus, but there may be an intermediate annulus or annuli, therebetween, with suitable friction-reducing means, as described above, between each pair of adjacent annuli. Thus, in accordance with the present invention there may further be a third rotatable annulus which is free to rotate between the inner and outer annuli, suitably with friction- reducing means, as described above, between each adjacent pair of annuli.

Suitably there are friction-reducing means, as described above, between the first annulus and the support. Such friction- reducing means between the first annulus and the support may be located directly therebetween. Preferably, however, they are located between the first rotatable annulus and an inner annulus which is non-rotatably mounted on the support, in use, for example by means of a keyway, spline, or bolt connection. The support is preferably a shaft.

Suitably the outer surface of the outermost annulus has a circumferential running surface, for example a groove, to receive an elongate textile article, for example a yarn, cord, string, rope or filament.

A bearing assembly in accordance with the invention may f ind use, f or example, as a twist stop device f or reducing the propensity of yarns to develop clumps or knots, in twist or false-twist production operations. In such embodiments the outer surf ace of the outer annulus may have yarn gripping means, such as teeth. However a preferred textile application of a bearing assembly in accordance with the invention is as a yarn guide.

In the past textile yarn guides have commonly been constituted by stationery surfaces. To prevent yarn damage these have been made with low-friction surfaces, for example of ceramic materials. Even so, the frictional forces have often been undesirably high. It has been proposed, therefore, to use roller bearing guides. The roller bearing guides used have had an inner, fixed, annulus and an outer, rotatable annulus, with spherical balls therebetween. However these have nt always been able to cope adequately with the very high speeds at which yarns may travel in a modern textile mill.. Furthermore, in the case of fine denier yarns, where the yarn tension is very low, the starting torque for these7 bearings was often too large to cause them to rotate freely. This introduced undesired drag on the yarns, leading to yarn damage, and in extreme cases they may be no better than fixed guides. There is a particular problem if dust gets inside the bearings and starting torque increases further.

We have found that by means of a double or multiple bearing assembly there is a very substantial reduction in starting torque. Furthermore, should one of the rotatable annuli stop rotating, it is likely that the or each other rotatable annuli will continue to rotate. The fact that one of the annuli has stopped rotating wIll be easily visible and the fault can be corrected by maintenance staff before rotation of the bearing assembly stops altogether.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic axial view of a first embodiment of yarn guide comprised by a bearing assembly in accordance with the present invention; Fig. 2 shows a second embodiment of yarn guide; Fig. 3 is a more detailed view of a yarn guide, in diametrical cross- section; and Fig. 4 shows a part of the yarn guide of Fig. 3, and 25 also represents a prior art single bearing assembly.

The yarn guide shown in Fig. 1 comprises a bearing assembly 2, secured about a fixed shaf t 4, in a manner such as to prevent axial movement of the bearing assembly 30 2.

The bearing assembly comprises an inner rotatable annulus 6 around the shaft, and carrying spherical balls 8 which are in contact with the shaft. It further comprises an outer rotatable annulus 10 around the inner 4.

A annulus 6. The outer annulus carries spherical balls 12 which slide on the outer surface of the inner annulus 6.

The outer annulus has a grooved circumf erential outer 5 surface, which receives and guides a yarn 14.

The yarn guide shown in Fig. 2 is similar to that shown in Fig. 1, except that the inner set of balls 8a do not slide directly on the shaft 4a. Rather, there is an additional annulus, a fixed inner annulus 16, which is secured against rotation on the shaft by means not shown, in this embodiment by a bolt and nut. The innermost set of balls 8a act between the fixed annulus 16 and the inner rotatable annulus 6a.

is The yarn guide shown in Fig. 3 is of the type shown in Fig. 2, having an inner, fixed annulus 16b. As in Fig. 2 there are spherical balls 8b between the inner, fixed annulus 16b and the inner rotatable annulus 6b. However, between the inner rotatable annulus 6b and the outer rotatable annulus lob there are cylindrical rollers 20, rather than spherical balls. Fig. 3 clearly shows the circumferential groove 22.

4 For the purposes of clarity, Fig..4 shows just the inner parts of the yarn guide of Fig. 4, i.e. without the outer annulus lob or the rollers 20.

Experiments to assess the force required to start rotation of the roller guide of the type shown in Fig. 3 in comparison to a prior art roller guide having only a single rotatable race, of the type shown in Fig. 4, have shown a most significant reduction in the required starting load. The part shown in Fig. 4 herein, of diameter limm, was used both in the single bearing device i i and the double bearing device of the present invention. In the case of the single bearing device an outer, grooved, yarn-receiving annulus was engaged on it, of diameter 13.5mm as measured from the bottom of the groove. In the case of the bearing assembly of the invention the outer annulus comprising the cylindrichl rollers 20 was engaged on the apparatus of Fig. 4, to produce the bearing assembly of Fig. 3. The diameter of the outer annulus, measured from the bottom of the groove, was20mm.

In the case of the bearing assembly of the invention, the mean starting load over ten tests was tomg. In the case of the single bearing, the mean starting load over ten tests was 1080mg.

The readerfs attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all subh papers and documents are incorporated herein by reference.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

Claims (13)

1. CLAINS

   A bearing assembly to support andlor receive andlor guide a linear textile article, the bearing assembly being mounted in use on a support, the assembly comprising an inner rotatable annulus which is free to rotate about the support and an outer rotatable annulus which is free to rotate about the inner annulus, the linear textile article being in contact with the outer annulus.
2. 2. A bearing assembly according to Claim 1, wherein friction-reducing means are provided between the inner annulus and the outer annulus.
3. 3. A bearing assembly according to Claim 2, wherein the friction-reducing means comprises rolling elements.
4. A bearing assembly according to any preceding claim, wherein the outer annulus runs directly about the inner annulus.
5. 5.

   A bearing assembly according to Claim 1, wherein the assembly comprises a third rotatable annulus which is free to rotate between the inner and outer annuli.
6. 6. A bearing assembly according to Claim 5, wherein friction-reducing means are provided between each adjacent pair of annuli.
7. 7.

   A bearing assembly according to any preceding claim, wherein frictionreducing means are provided between the first annulus and the support.
8. 8. A bearing assembly according to Claim 7, wherein the friction-reducing means are located between the first rotatable annulus and an inner annulus which is nonrotatably mounted on the support.
9. 9. A bearing assembly according to any preceding claim, wherein the outer surface of the outermost annulus has a circumferential running surface to receive an elongate textile article.
10. 10. A bearing assembly according to any preceding claim, adapted for use as a twist stop device for reducing the propensity of yarns to develop clumps or knots, in twist or false-twist production operations.

    is
11. 11. A bearing assembly according to Claim 10, wherein the outer surface of the outer annulus has yarn gripping means.
12. 12. A bearing assembly according to any of Claim 1 to 9, adapted for use as a yarn guide.
13. 13. A bearing assembly substantially as hereinbefore described, with reference to and as illustrated in 25 the accompanying drawings.