GB2069628A

GB2069628A - Angular contact rolling bearing cage

Info

Publication number: GB2069628A
Application number: GB8040299A
Authority: GB
Original assignee: Timken Co
Current assignee: Timken Co
Priority date: 1980-02-20
Filing date: 1980-12-16
Publication date: 1981-08-26
Also published as: GB2069628B

Abstract

A cage particularly for a tapered roller bearing comprises a large end ring 2 and a small end ring 1 both of plastics material joined by integral connecting bars 3, also of plastics material, which define pockets for receiving the bearing rollers. The bars are shaped to define a groove 6 which extends axially along the inner face. The various grooves 6 are commoned in an annular trough 4 into which lubricant may be supplied. During use, lubricant passes from the trough 4 along the grooves 6 from right to left by centrifugal force, thus leading to an improved distribution of lubricant within the bearing. In practice the assembly will require reinforcement if it is to withstand the high centrifugal forces encountered during use. One way of achieving such reinforcement is to make the assembly a snap fit within a conventional metal cage. <IMAGE>

Description

SPECIFICATION Improvements relating to rolling bearings This invention relates to angular contact rolling bearings and more particularly to cage assemblies for use in such bearings and which are formed mainly of a suitable polymer, such as nylon.

Polymer cages are of course known but there are certain applications where their use is not advisable without some reinforcement which in some aspects of this invention may be provided by means of a metal cage of conventional construction.

More especially in the case of high speed applications special means for lubricating the roller-guiding rib at the large diameter end of the inner race member of the bearing is desirable and two such arrangements which use an all metal construction are described in our British Specification No. 1 328300. In one arrangement some of the bars of a cage formed of sheet metal have secured thereto a distribution tube which extends from a collection trough at the small diameter end of the cage along part of the bar and then diverges therefrom towards the junction between the rib and the raceway of the inner race member.

In the other arrangement a cage formed as a casting is provided with distribution holes which extend axially through the body of the cage and open at one end in a collection trough and at the other end adjacent the junction between the rib and the raceway of the inner race member.

It is an object of the present invention to provide an improved arrangement of this kind which is particularly suitable for use where the cage assembly is formed mainly of a polymer.

According to one aspect of the invention there is provided a cage assembly for an angular contact rolling bearing wherein at least some of the bars of the assembly which extend between and locate the rolling elements of the bearing are shaped in section to define an axially-extending groove open on the radially inner side of the cage and along which during use of the bearing, lubricating fluid may flow by centrifugal action.

It will be seen that the use of an open groove, as opposed to a closed tube or bore enables the bars to be readily and cheaply fabricated as plastics mouldings. In another aspect. the invention provides a plastics inset for a rolling bearing cage assembly, said insert comprising a plurality of bars joined at their ends by integral large and small diameter end rings to define a generally frustoconical shape, and wherein at least some of said bars are shaped in section to define as axially-extending groove open on the radially inner side of the insert along which, during use of the bearing, lubricating fluid may flow by centrifugal action. It is generally considered that, for use in high-speed bearings, the plastics insert will require reinforcement, for example by being supported by a conventional metal cage.In one form of the invention the arrangement is such that the cage assembly once assembled on the inner race member will be self retained and cannot accidentally be removed therefrom.

The centrifugal action is achieved by ensuring that the bottom of the groove is closer to the axis of rotation at one end of each bar than at the other, so that lubricating fluid, for example oil, which is introduced into the closer end will travel along the groove by virtue of the centrifugal force during rotation of the bearing which imparts to the fluid a force away from the axis.

In an embodiment of the invention, the respective grooves are joined, at their "inner" ends, by an annular collecting trough to which, during use, lubricant is supplied for distribution along the various grooves.

The invention finds particular application in tapered roller bearings where the bars are shaped to fit between the bearing rollers and have their radially inner faces extending adjacent the raceway of the inner race member.

The exit end of each groove is adjacent the roller-guiding rib of the inner race member which thus ensures that the rib receives an adequate supply of lubricant during use.

The present invention will now be described with reference to the accompanying drawings, wherein Figure 1 is a longitudinal section taken through a moulded cage insert; Figures 2 and 3 are part section taken respectively at 'AA' and 'BB' in Fig. 1 through the bars which connect the ring like parts at either end of the cage insert; Figure 4 is a perspective view of a part of the cage insert; and Figure 5 is a longitudinal section of a tapered roller bearing fitted with a standard metal cage containing the insert of Fig. 1.

Referring now to Figs. 1 to 4, the cage insert, which is formed of a suitable polymer, comprises two end rings 1 and 2 joined by integral connecting bars 3 which form between them pockets for receiving the tapered rollers. The ring 1 extends axially beyond the face of the bearing inner race; in the bore of this extension is an annular groove 4 which forms a collecting trough for the lubricant, and on the outside diameter of this extension is a slight rib 5 which extends radially from the surface of the extension. The connecting bars 3 which vary in section from one -end to the other as shown in Figs. 2 and 3, are formed with a groove 6 which extends axially along the inner face of each bar. As shown the depth of the groove 6 varies becoming progressively more shallow towards the large diameter end of the insert, but it may be of constant depth throughout the length of the bar.While in general the shape of the bars 3 may be such that the groove 6 is positioned radially further from the centre line of the insert as it approaches the exit point at the large diameter end, in the form illustrated the bore of the insert as delineated by the radially inner face of the connecting bars 3 is slightly larger than the bearing inner race with which it is intended to cooperate so that the inner face of each bar lies closely adjacent the race all along its length.

The axial grooves 6, as shown more clearly in Fig. 4, connect with the annular groove 4 at the small diameter end of the insert and have an open exit end 7 at the other end of the bars 3.

As shown in Fig. 5 the outside surface 8 of the ring 1 of the insert fits closely to the inside surface of a metal cage 9 of conventional design while the rib 5 of the axial extension is slightly larger in diameter than the bore of the metal cage at 10.

The bearing inner race member is of conventional form with the exception of the riblike extension 11 which is machined to a slightly smaller outside diameter than the bore 1 2 of the ring 1 of the insert.

Referring to Figs. 2 and 3 the surfaces 1 3 and 14 of the bars 3 of the insert are substantially parallel as seen in a section perpendicular to the axis of a roller in its normal position between them and they are spaced to provide a limited clearance about such roller. As shown in Figs. 1 and 3 the surface of the lips 15, which define the groove 6, at their ends 1 spa adjacent the ring 1 project radially inwards beyond the bore 1 2 in this ring.

Assembly of the bearing proceeds as follows: the insert is pressed into a standard metal cage 9 so that the rib 5 is forced through the bore 10 of the cage and a snap assembly results. The fit of the insert in the metal cage is such that the pockets in the insert and the metal cage can be correctly aligned when the tapered rollers are inserted.

Tapered rollers are then inserted from the inside of the cage assembly. The lips 1 5 of the connecting bars 3 are compliant enough to allow the rollers to be inserted, although the width of the pocket at this point may be slightly less than the diameter of the roller.

The metal cage, being of standard construction, prevents the rollers escaping from the pockets in a radially outward direction.

The cage assembly, complete with rollers, is then fitted over the inner race member. Because the insert. as has already been described, is smaller in bore 1 spa than the diameter of the extension 11 of the inner race member, and since the insert is compliant the lips 1 5 will elastically deform and allow the insert to pass over the extension 11. The cage assembly will then be retained on the inner race member and the contour of the lips of the connecting bars 3 at 1 spa is such that it is favourable to a snap assembly but unfavoura ble to accidental dismantling.

The assembled combination cage, rollers and bearing inner race may be handled safely in the same manner as a standard tapered roller bearing assembly.

The action of this assembly will now be described: The groove 6 forms a channel along which lubricant may pass aided by centrifugal force.

In the embodiment shown the inner faces of the bars 3 are very close to the bearing inner race but this is not considered essential to the containment of the lubricant in the groove.

Some of the lubricant, introduced by jets at.

the small diameter end of the assembly, is centrifuged from the annular groove or collecting trough 4 along the grooves 6 and onto the face 1 6 of the roller-guiding rib. As the lubricant escapes at a radially low point adjacent to this rib and because this rib overhangs the exit point 7, its face 1 6 is sprayed with lubricant in the path of the ends 1 7 of the tapered rollers.

By fitting the described insert to a standard cage it is possible to make efficient use of available lubricant, for instead of all the lubricant passing through the bearing among the roller bodies, some is diverted along the channels in the insert directly to the rib at the large diameter end of the inner race member.

Not only is more efficient use made of the available lubricant but losses due to churning are reduced.

The rollers being confined by an insert which can be made to a closer circumferential fit than is possible with a pressed metal cage are given better guidance and spacing, while wear on the rollers is reduced because in operation they are spaced by contact with the polymer insert and not by the metal cage.

Another benefit resulting from the use of a polymer cage insert, made for example of nylon, is that in the event of an accidental breakdown of force lubrication the bearing can be brought to rest without damage to the metal cage, the rollers or the bearing races, because the insert acts sacrificially as a lubricant. It is envisaged that filled polymers can be formulated to extend the lubricating ability of the insert in the case of an emergency.

The assembly of the insert in a more or less standard metal cage may be effected in other ways. For example the insert could be moulded onto the metal cage, it could be secured to the cage by a suitable adhesive, it could be secured by providing it with lugs that pass through slots formed in the radial flange of the cage and are engaged with the cage by relative rotation in the manner of a bayonet fastener.

In a modification the insert and cage could be formed as a single moulding which is suitably reinforced so that it can withstand the centrifugal force to which it will be subjected when it is in use.

It is contemplated that some of the advantages of the above described arrangements could be obtained by a modification in which individual bars, similar in shape to the bars 3 as described above, are used and which on assembly are introduced between the rollers and within a metal cage.

Claims

1. A cage assembly for an angular contact rolling bearing wherein at least some of the bars of the assembly which extend between and locate the rolling elements of the bearing are shaped in section to define an axiallyextending groove open on the radially inner side of the cage and along which, during use of the bearing, lubricating fluid may flow by centrifugal action.

2. A cage assembly as claimed in claim 1 wherein the bars are of plastics material.

3. A cage assembly as claimed in either one of claims 1 or 2 wherein the bottom of each groove is closer to the axis of rotation at one end than at the other, and wherein means are provided for introducing lubricating fluid into said one end of each said grooves.

4. A cage assembly as claimed in claim 3 wherein said lubricating fluid introducing means comprises an annular trough with which said one end of each of the grooves communicates.

5. A plastics insert for a rolling bearing cage assembly, said insert comprising a plurality of bars joined at their ends by integral large and small diameter end rings to define a generally frusto-conical shape, and wherein at least some of said bars shaped in section to define an axially-extending groove open on the radially inner side of the insert along which, during use of the bearing, lubricating fluid may flow by centrifugal action.

6. A plastics insert as claimed in claim 5 wherein the small diameter end ring is provided with an annular collecting trough with which the grooves in the bars connect.

7. A plastics insert as claimed in either one of claims 5 or 6 wherein the facing surfaces of adjacent bars are shaped so as to retain a rolling element therebetween.

8. A plastics insert as claimed in claim 7 wherein the bars are shaped in such a way that, during assembly, rolling elements may be pushed by hand into position between adjacent bars and retained therein for assembly purposes due to the resilience of the plastics bars.

9. A cage assembly as claimed in claim 2 comprising a plastics insert as claimed in any one of claims 5 to 8 which is reinforced by attachment to a metal cage.

10. A cage assembly as claimed in claim 9 wherein the plastics insert is a snap fit in the metal cage.

11. A cage assembly as claimed in claim 9 wherein the plastics insert is moulded in situ within the metal cage.

1 2. A cage assembly as claimed in claim 9 wherein the insert is secured to the cage by means of adhesive.

1 3. A cage assembly as claimed in claim 9 wherein the insert is secured to the cage by providing it with lugs that pass through slots formed in the radial flange of the cage and are engaged with the cage by relative rotation in the manner of a bayonet fastener.

1 4. A cage assembly as claimed in claim 9 wherein the insert and cage are formed as a single moulding which is reinforced so as to withstand the centrifugal force to which it is subjected during use.

1 5. A cage assembly for an angular contact rolling bearing substantially as hereinbefore described with reference to the accompanying drawings.

16. An angular contact rolling bearing comprising an inner and an outer race member, a cage assembly as claimed in any one of claims 1 to 4 or 9 to 1 5 and a plurality of rolling elements.

1 7. An angular contact rolling bearing as claimed in claim 16 wherein the rolling elements are rollers and wherein the exit end of said grooves is directed onto the roller-guiding rib of the inner race member.

1 8. An angular contact rolling bearing as claimed in either one of claims 1 6 or 1 7 wherein the bars extend radially inwardly slightly beyond the general internal surface of the cage assembly so that, during assembly of the bearing as the inner race member is assembled to the cage assembly, the protruding parts of the bars will deform and then latch behind the corresponding end of the inner race member.

1 9. An angular contact rolling bearing as claimed in claim 1 6 substantially as hereinbefore described with reference to Fig. 5 of the accompanying drawings.