GB2290116A - Bearing assemblies - Google Patents

Abstract

A method of manufacturing a rectilinear-motion rolling bearing assembly (1) comprises the steps of forming a support cage (2) having a plurality of recesses (6), forming a plurality of bearing elements (4) such that each bearing element is attached to a common bearing element carrier (which may be the cage), inserting each bearing element into a corresponding recess in which it is retained in the cage, and severing the attachment (8) between each bearing element and the common bearing element carrier. The support cage and bearing elements may be formed substantially simultaneously as plastics mouldings, the bearing elements being formed adjacent to the support cage. The cage is then passed through a pair of rollers of a press which force each bearing element in turn into its respective recess. The bearing assembly may be adapted to receive a runner, such as used in drawers of household and office furniture. <IMAGE>

Description

BEARING ASSEMBLIES This invention relates to bearing assemblies in which a plurality of bearing elements are retained within a supporting cage and a method of manufacturing such assemblies.

In a known method of manufacturing bearing assemblies a supporting cage and a plurality of bearing elements, which may be ball bearings or rollers for example, are manufactured separately; the bearing elements are subsequently assembled with the cage such that each element is retained in the cage free to rotate about at least one axis.

The need for separate manufacturing processes for the cage and each individual bearing element and, in addition, for a subsequent process to assemble the loose bearing elements with the cage increases the time and cost required to produce such assemblies.

It is an aim of the present invention to provide an improved bearing assembly and a method of manufacturing the same.

According to a first aspect of the invention, there is provided a method of manufacturing a bearing assembly comprising the steps of: a) forming a support cage having a plurality of recesses; b) forming a plurality of bearing elements such that each bearing element is attached to a common bearing element carrier; c) inserting each bearing element into a corresponding recess in which it is retained in the cage; d) severing the attachment between each bearing element and the common bearing element carrier.

Each of the plurality of bearing elements may be attached to the cage such that the cage provides the common bearing element carrier.

According to a second aspect of the present invention, there is provided a method of manufacturing a bearing assembly in which a supporting cage having a plurality of recesses and a plurality of bearing elements are formed together, substantially simultaneously, the bearing elements being formed adjacent to the supporting cage, and each bearing element is subsequently inserted into a corresponding recess in which it is retained in the cage.

The cage and the bearing elements may be produced by a moulding process; they may be moulded from the same or from different materials. Preferably, the cage and the bearing elements are produced in a plastics material by an injection moulding process.

The bearing elements may be in the form of rollers or balls. In the form of rollers they may be needle rollers.

Each bearing element may be attached to the cage during the forming operation, preferably adjacent a respective recess formed in the cage to accept that bearing element. The attachment may be by means of a tag which may be moulded integrally with the cage and the bearing element. The tag may be frangible and may attach its respective bearing element to a side surface of the cage. The tag may extend obliquely from the cage holding its respective bearing element away from the cage adjacent to the recess which is to accept that bearing element.

Each recess may be part-circular in form and may have an outwardly extending opening through which the respective bearing element may pass into the recess.

The material of the cage bordering upon the opening is preferably resilient. The opening may be formed as a slight interference fit with the bearing element and be resiliently expandable to allow the bearing element to be forced through it into the recess so that, once inserted, the bearing element cannot easily fall out of the recess through the opening. The recess is preferably adapted normally to retain the bearing element once it has been inserted.

In order to assemble the bearing elements in the cage, each roller element may simply be pushed into its respective recess in the cage through the respective opening. A press may be used to push the bearing elements into their respective recesses; the press may comprise a surface that acts against the individual bearing elements. The press may comprise a roller or rollers which act on the individual bearing element; in this case, the roller or rollers of the press may draw the cage forwards in linear motion such that each bearing element is pressed into its respective recess as it passes through the roller or rollers of the press.

The cage may be of substantially U-shaped cross-section and the recesses may be provided in each leg of the U. The channel between the legs of the U may be adapted to receive a member, for example a runner, against which the bearing elements act in use.

According to a further aspect, the present invention comprises a bearing assembly manufactured according to the first or second aspect of the invention.

Bearing assemblies manufactured in accordance with the method of the first or second aspect of the present invention are particularly suitable for applications where relatively light loads are imposed on the bearing elements. The bearing assemblies may be used for household and office furniture and are particularly suited for use in runners for drawers. It will be appreciated, however, that the present invention has many further applications.

According to a yet further aspect, the present invention provides a piece of furniture which has a bearing assembly manufactured in accordance with the method of the first or second aspect of the invention.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a front view of a cage of a bearing assembly; Figure 2 shows a section along line 2'-2' of Figure 1; Figure 3 shows a rear view of a semi-finished bearing assembly manufactured in accordance with the method of the present invention; and Figure 4 shows a side view of part of the completed bearing assembly.

In this embodiment a bearing assembly 1 is made which comprises an elongate cage 2 and a plurality of individual roller elements 4 in the form of needle rollers. The entire assembly is made as a single injection moulding of a suitable plastics material.

The moulding as formed is shown in Figure 2; this is a semi-finished form of the assembly.

The cage 2 formed in the moulding is substantially U-shaped in cross section and is provided with a plurality of recesses 6 in each leg of the U equally spaced apart along the length of the cage, the recesses in the one leg of the U being staggered with respect to the recess in the other leg. Each recess 6 is of part-cylindrical form, of larger diameter than the thickness of the leg of the U, adapted to receive and retain a respective roller element 4. The central longitudinal axes of the recesses are parallel and extend transversely of the cage between its front and rear faces, parallel to opposite sides of the cage.

Each recess 6 has a first opening 14 provided in the exterior side of the leg through which one of the roller elements 4 may be inserted into that recess.

When a roller has been inserted into a recess (as shown in Figure 4) a first part of the roller protrudes through the first opening 14 beyond the exterior side of the leg and a second part of the roller extends through a second opening 18 beyond the interior side of the leg. A front wall 10 closes a forward end of each recess 6, an opposite rearward end of each recess being partially closed by a rear wall 12. In use each roller is retained by but rotatable within its respective recess.

Each roller element 4 is of complimentary diameter and length to its respective recess and is attached by an integral tag 8 to a side surface of the cage 2. The side of the cage thus provides a common bearing element carrier for the roller elements of that side. Each tag 8 extends obliquely from the cage 2 so that its roller element 4 is held adjacent and parallel to the opening 14 of its respective recess 6 extending across the side of the cage. The opening 14 extends for the length of the recess 6 and is narrower than the diameter of the roller it is to receive. Opposite the opening 14 each recess has a further, comparable, opening 18, into the channel of the U-shape of the cage.

In order to assemble the roller elements 4 in the cage 2, the semi-finished assembly shown in Figure 2 is passed through a pair of opposed rubber faced rollers of a press (not shown) from its one end 16. The rollers of the press force each roller element 4 in turn to be pushed through the opening 14 into its respective recess 6, the material of the cage bordering the opening being sufficiently resilient to allow the opening to expand temporarily to allow the roller element to pass through it. As the roller element 4 enters its recess 6 its tag 8 breaks away from its attachment with the cage 2. The tag 8 at this point is still attached to the roller element 4 but breaks away when the roller element 4 rotates in its recess 6 during its initial use. Alternatively, the tag could be adapted to break away from its roller element 4 during insertion into its respective recess 6. The restricted openings and the front and end walls 10,12 retain the roller elements in the recesses 6.

The illustrated bearing assembly is particularly suited for use as part of a runner for a drawer as more fully described in our co-pending UK Patent Application filed on 11th June, 1994.

Since the rollers are of diameters larger than the thickness of the legs of the U shape of the cage, portions of their cylindrical surfaces protrude from the legs through the openings 14 and the further openings at the channels, and so provide bearing surfaces outside and inside the legs.

Claims (26)

1. A method of manufacturing a bearing assembly comprising the steps of: a) forming a support cage having a plurality of recesses; b) forming a plurality of bearing elements such that each bearing element is attached to a common bearing element carrier; c) inserting each bearing element into a corresponding recess in which it is retained in the cage; and d) severing the attachment between each bearing element and the common bearing element carrier.

2. A method according to claim 1 in which the bearing elements are formed adjacent to the cage.

3. A method according to claim 1 or claim 2 in which the support cage and the bearing elements are formed substantially simultaneously.

4. A method according to claim 2 or claim 3 as dependant on claim 2 in which the cage provides the common bearing element, and each of the plurality of bearing elements is attached to the cage.

5. A method according to any preceding claim in which the cage is formed by a moulding process.

6. A method according to any preceding claim in which the bearing elements are formed by a moulding process.

7. A method according to claims 5 and 6 in which the moulding process in an injection moulding process.

8. A method according to claims 5 and 6 or claim 7 in which the cage and bearing elements are moulded from different materials.

9. A method according to claims 5 and 6 or claim 7 in which the cage and bearing elements are moulded from like materials.

10. A method according to any preceding claim in which the bearing elements are in the form of balls.

11. A method according to any of claims 1 to 9 in which the bearing elements are in the form of rollers.

12. A method according to claim 11 in which the rollers are needle rollers.

13. A method according to claim 4 or any of claims 5 to 12 as dependant from claim 4 in which each bearing element is attached to the cage during the forming operation.

14. A method according to claim 13 in which each bearing element is attached to the cage adjacent a respective recess formed in the cage to accept that bearing element.

15. A method according to claims 13 or 14 in which each bearing element is attached to the cage by means of a tag.

16. A method according to claim 16, in which each tag attaches its respective bearing element to a side surface of the cage.

17. A method according to claim 15 or claim 16 in which each tag is frangible.

18. A method according to any preceding claim in which each recess is part circular in form.

19. A method according to any preceding claim in which each recess has an opening through which the respective bearing element is inserted into the recess and which is formed as an interference fit with each respective bearing element thereby to retain the inserted bearing element in the recess.

20. A method according to claim 19 in which a press is used to insert each bearing element through the opening into the respective recess.

21. A method according to claim 20 in which the press comprises a roller or rollers whereby each bearing element is caused to be pressed into the respective recess.

22. A method according to any preceding claim in which the cage is of substantially U-shaped cross section, comprising two spaced legs and a channel between the legs, the recesses being provided in each of the legs, and the channel being adapted to receive a member against which the bearing elements act in use.

23. A method according to claim 22 in which the member which the channel is adapted to receive is a drawer runner.

24. A bearing assembly manufactured by the method as claimed in any preceding claim.

25. A method of manufacturing a bearing assembly substantially as described herein with reference to the accompanying drawings.

26. A bearing assembly substantially as described herein with reference to the accompanying drawings.