WO2013052822A1

WO2013052822A1 - Cages for rolling element bearings and method of manufacture

Info

Publication number: WO2013052822A1
Application number: PCT/US2012/058992
Authority: WO
Inventors: Douglas H. Smith; Martin D. Pierce; Ming He
Original assignee: Timken Co
Current assignee: Timken Co
Priority date: 2011-10-06
Filing date: 2012-10-05
Publication date: 2013-04-11
Anticipated expiration: 2014-04-06

Abstract

A cage for a rolling element bearing includes a generally ring-shaped wall defining an axis. The wall has a first axial edge and a second axial edge opposite the first axial edge. The cage also includes a circumferential row of spaced-apart openings formed in the wall and configured to receive a plurality of rolling elements. The wall is tapered toward at least one of the first axial edge and the second axial edge by a plurality of individual deformations formed in the wall.

Description

CAGES FOR ROLLING ELEMENT BEARINGS AND METHOD OF

MANUFACTURE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No.

61/544,118, filed October 6, 2011, the entire contents of which are incorporated by reference herein.

BACKGROUND

[0002] The present invention relates to cages that retain rolling elements in position in a rolling element bearing. In particular, the manufacturing of cages for large (about 2-4 feet in diameter) and ultra-large bearings (about 4-10 feet in diameter), or low production volume bearings, especially tapered or spherical bearings, can be disproportionately expensive in the overall manufacture of a bearing.

[0003] For example, tooling and process control are typically highly specialized for each different cage having a unique diameter or taper shape. Furthermore, a large tapered cage that is spin-formed from a sheet results in large amounts of waste material.

SUMMARY

[0004] In one embodiment, the invention provides a cage for a rolling element bearing. The cage includes a generally ring-shaped wall defining an axis. The wall has a first axial edge and a second axial edge opposite the first axial edge. The cage also includes a circumferential row of spaced-apart openings formed in the wall and configured to receive a plurality of rolling elements. The wall is tapered toward at least one of the first axial edge and the second axial edge by a plurality of individual deformations formed in the wall.

[0005] In another embodiment, the invention provides a method of manufacturing a tapered cage for a rolling element bearing. The method includes providing a substantially flat strip having a first lengthwise edge, a second lengthwise edge opposite the first lengthwise edge, a first end, and a second end opposite the first end. The method also includes forming a plurality of individual deformations along a length of the strip proximate at least one of the first and second lengthwise edges to impart a tapered ring shape into the strip, whereby the first end and the second end are adjacent each other. The method further includes forming a circumferential row of spaced-apart openings in the strip. Each opening is configured to receive a rolling element. The method also includes coupling the first end and the second end together to form a unitary ring defining an axis. The first lengthwise edge becomes a first axial edge and the second lengthwise edge becomes a second axial edge of the unitary ring.

[0006] In yet another embodiment, the invention provides a method of manufacturing a tapered cage for a rolling element bearing. The method includes providing a substantially flat strip having a first lengthwise edge, a second lengthwise edge opposite the first lengthwise edge, a first end, and a second end opposite the first end. The method also includes deforming at least one of the first lengthwise edge and the second lengthwise edge along a length of the strip to impart a tapered ring shape into the strip, whereby the first end and the second end are adjacent each other. The method further includes forming a circumferential row of spaced-apart openings in the strip. Each opening is configured to receive a rolling element. The method also includes coupling the first end and the second end together to form a unitary ring defining an axis. The first lengthwise edge becomes a first axial edge and the second lengthwise edge becomes a second axial edge of the unitary ring.

[0007] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Fig. 1 illustrates various stages of manufacture of a portion of a cage for a conical rolling element bearing according to one aspect of the present invention.

[0009] Fig. 2 is a detail view of one side of the cage portion, after shaping and prior to forming rolling element pockets therein.

[0010] Fig. 3 is a detail view of another side of the cage portion, after shaping and prior to forming rolling element pockets therein.

[0011] Fig. 4 is a detail end view of a first axial edge of the cage portion, after shaping and prior to forming rolling element pockets therein.

[0012] Fig. 5 illustrates the assembled cage of Fig. 1 with a plurality of rolling elements positioned in the cage. [0013] Fig. 6 is a perspective view of a male and female die set used in shaping the cage from a flat strip.

[0014] Figs. 7 and 8 illustrate a method of shaping the flat strip into tapered form by creating a series of individual deformations along the strip with the male and female die set of Fig. 6.

[0015] Fig. 9 illustrates two tapered cage portions that can be joined to form a cage for a spherical rolling element bearing.

[0016] Fig. 10 illustrates the assembled cage of Fig. 9 with a plurality of rolling elements positioned in the cage.

[0017] Fig. 11 illustrates a portion of a cage for a conical rolling element bearing according to another aspect of the present invention.

[0018] Fig. 12 illustrates a portion of a cage for a conical rolling element bearing according to yet another aspect of the present invention.

DETAILED DESCRIPTION

[0019] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.

[0020] Fig. 1 illustrates a portion of a cage 20 for a conical rolling element bearing (not shown). It should be understood that the cage 20 would actually extend fully around an axis 23 to form a ring, as shown in Fig. 5. The cage 20 is assembled between inner and outer races of the bearing to retain a plurality of rolling elements 22 (Fig. 5) in position (e.g., circumferentially spacing the rolling elements 22 from one another).

[0021] The illustrated cage 20 includes a wall 24 having a first side 24 A and a second side 24B opposite the first side 24A. The wall 24 has a first axial edge 28A and a second axial edge 28B opposite the first axial edge 28A. A plurality of openings or "pockets" 32 are formed in the wall 24 between the axial edges 28A, 28B. The illustrated pockets 32 are spaced-apart and arranged in a circumferential row to receive the rolling elements 22 (Fig. 5). It should be understood that the pockets 32 can be formed in different shapes and spacings, and that multiple rows of pockets 32 may be included in a single cage 20.

[0022] As described in further detail below, the cage 20 shown in Fig. 1 is manufactured from a flat straight strip 36. The flat strip 36 can be steel or another metal suited for shaping by die pressing or similar processes. In the illustrated construction, the flat strip 36 is generally planar and straight. In other constructions, the flat strip 36 may initially be slightly curved before any manufacturing processes are carried out on the strip 36.

[0023] Referring now to Figs. 6-8, a male die 40A and a female die 40B form a die set 40 coupled to a hydraulic press 44. The male die 40A includes a linear blade or projection 48 having a length of projection L from a reference surface 52 that varies along the male die 40A. The projection 48 is variable in that one end (e.g., the upper end) of the projection 48 extends further from the reference surface 52 than the other end (e.g., the lower end) of the projection 48. The projection 48 is adjustable within the male die 40A via a plurality of fasteners 54 (Fig. 6) to change the amount the projection 48 extends from the die 40A. The projection 48 may also be replaceable by an alternately- shaped projection. The female die 40B has a corresponding recess 56 that has a variable depth D from its reference surface 60, corresponding to the variable-length projection 48. Similar to the projection 48, the recess 56 is variable in that one end (e.g., the upper end) of the recess 56 is relatively deeper than the other end (e.g., the lower end) of the recess 56. As shown in Figs. 7 and 8 and described in further detail below, the die set 40 is pressed together on the flat strip 36 to shape the cage 20.

[0024] With further reference to Figs. 7 and 8, the flat strip 36 is fed into the die set 40 on the press 44, and the dies 40A, 40B are closed onto the flat strip 36 to create a deformation 66 in the flat strip 36 that corresponds to the shape of the projection 48 and the recess 56. Due to the shape of the projection 48, each deformation 66 is shaped to have an increasing amount of deformation in the axial direction toward the first edge 70, as shown in Figs. 1-4.

Referring back to Figs. 7 and 8, after a deformation 66 is formed, the dies 40A, 40B are separated, the now partially-formed flat strip 36 is advanced incrementally across the die set 40, and the dies 40A, 40B are again closed onto the flat strip 36 to form another deformation 66. The process is repeated until a plurality of similar deformations 66 are formed along the entire length of the strip 36, from a first or leading end 74A to a second or trailing end 74B (Fig. 5). In the illustrated construction, all of the deformations 66 are the same shape and size, but may alternatively have varying shapes and/or sizes.

[0025] Due to the shape of the die set 40, the flat strip 36 is gradually shaped into a tapered ring form by the above-described sequence of pressing operations. In particular, the die set 40 creates a first amount of deformation adjacent a first edge 70 of the flat strip 36 (corresponding to the first axial edge 28A of the cage 20) and creates a second, smaller amount of deformation adjacent a second edge 72 of the flat strip 36 (corresponding to the second axial edge 28B of the cage 20). The amount of deformation to the flat strip 36 varies gradually between the first and second edges 70, 72, depending on the shape of the projection 48. As more and more deformations 66 are formed in the flat strip 36, the first edge 70 of the strip 36 gradually becomes gathered to take on a reduced overall dimension, while the second edge 72 is gathered a lesser amount or not gathered at all. As such, the first edge 70 becomes relatively shorter than the second edge 72. In the finished cage 20, a portion of which is shown in Fig. 1, the wall 24 is tapered toward the first axial edge 28A. In other words, the effective diameter of the cage 20 at the first axial edge 28A is less than the effective diameter of the cage 20 at the second axial edge 28B.

[0026] After forming the deformations 66 in the flat strip 36 with the die press 44, a semi-formed cage 20' exists that is in generally ring form but has adjacent loose ends and has no pockets 32 therein. Although only shown as an exemplary segment rather than as a full ring, the semi-formed cage 20' is illustrated in Figs. 1-4. To complete the manufacture of the cage 20, the two opposing ends 74A, 74B of the semi-formed cage 20' are coupled together and the pockets 32 are formed through the wall 24. In some constructions, the ends 74A, 74B of the semi-formed cage 20' are coupled together by welding, such that the ends 74 A, 74B are connected at a weld line 76 (Fig. 5). The plurality of pockets 32 may then be formed by water jet cutting or using other suitable means to cut the wall 24 after the ends 74A, 74B are coupled. Alternate methods for forming the pockets 32 include punching, milling, or laser cutting, for example. Furthermore, it may be desirable to form the pockets 32 directly in the flat sheet 36 prior to any shaping operation(s) or after the deformations 66 are formed, but before the ends 74A, 74B are coupled together. In the illustrated construction, one pocket 32 is formed between each pair of adjacent deformations 66, and likewise, one deformation 66 is formed between each pair of adjacent pockets 32. In other constructions, such as those discussed below with reference to Figs. 11 and 12, the deformations 66 can be formed to extend into the pockets 32.

[0027] In some constructions, to reduce the severity or depth of the deformations 66, yet still obtain the desired tapered wall angle, the second edge 72 may be lengthened relative to the first edge 70. In such constructions, the second edge 72 may be stretched before or after the deformations 66 are formed in the wall 24 to further increase the length of the second axial edge 28B relative to the first axial edge 28A. In other constructions, the flat strip 36 may start out slightly curved to reduce the severity of deformations needed to create a cage with a large angle.

[0028] Fig. 5 illustrates the cage 20 with the rollers 22 positioned in the pockets 32. The cage 20 is tapered toward the central axis 23 from the second axial edge 28B to the first axial edge 28A such that the first axial edge 28 has a generally smaller diameter than the second axial edge 28B. In the illustrated construction, all of the deformations 66 are formed to project toward the inside of the cage 20 (i.e., toward the axis 23) so that the deformations 66 have adequate clearance and do not interfere with the rollers 22. Although the cage 20 is shown with twenty-two rollers 22 and twenty-two pockets 32, it should be understood that the cage 20 can include more rollers and pockets to achieve diameters in excess of two feet.

[0029] Fig. 9 illustrates two semi-formed cages 20' positioned with their second axial edges 28B (lesser- or un-deformed edges) in abutting relation. The two semi-formed cages 20' can be coupled (e.g., by welding) along their second axial edges 28B to form an assembled cage 120 having the shape of a truncated sphere, as shown in Fig. 10, for use with a "spherical" rolling element bearing. The illustrated two semi-formed cages 20' are relatively positioned so that the deformations 66 of the two semi-formed cages 20' are offset or staggered from one another. In such a construction, the pockets 32 and corresponding rolling elements 22A will also be offset from one another. Alternately, the semi-formed cages 20' may be coupled such that the deformations 66 and the pockets 32 of the two semi- formed cages 20' are in register or inline with one another. It should also be appreciated that the pockets 32 may be formed prior to or after the two semi-formed cages 20' are coupled together.

[0030] Fig. 10 illustrates the assembled cage 120 with the rollers 22A positioned in the pockets 32. The assembled cage 120 is shaped like a truncated sphere such that the first axial edges 28 A of both cages 20 have generally smaller diameters than the diameter at the midsection of the assembled cage 120 (i.e., where the second axial edges 28B are coupled together). In this construction, the first axial edge 28A of the upper cage 20 forms one of the axial edges of the assembled cage 120, while the first axial edge 28 A of the lower cage 20 forms the other axial edge of the assembled cage 120. Although the assembled cage 120 is shown with twenty-two rollers 22A and twenty-two pockets 32 in each cage 20, it should be understood that each cage 20 can include more rollers and pockets to achieve diameters in excess of two feet. In other constructions, the assembled cage 120 may alternatively be designed for use with tapered roller elements, such as those shown in Fig. 5.

[0031] In further constructions, a cage for a spherical rolling element bearing may be constructed from the single flat strip 36 by simultaneously forming deformations proximate both edges 70, 72 of the flat strip 36 with a die set that is so configured. This illustrates another advantage of the invention, which is that a multitude of different cages having different diameters and taper shapes may be constructed merely by exchanging the die set 40 for an alternate die set (or in the case of various conical cages, merely adjusting the projection 48 of the male die 40A). In some constructions, the die set 40 may be replaced with a die set having a curved projection to form curved, rather than conical, cages.

[0032] Fig. 11 illustrates a portion of another cage 220 for a conical rolling element bearing. Similar to the cage 20 described above, the illustrated cage 220 includes a wall 224 having a first side 224A, a second side 224B, a first axial edge 228A, and a second axial edge 228B. In the illustrated construction, however, deformations 266 are formed in

communication with pockets 232, rather than between adjacent pockets 232. As shown in Fig. 11, one deformation 266 is inline with each pocket 232 to shorten the first axial edge 228A of the wall 224 relative to the second axial edge 228B. Such an arrangement may be employed if the width of material between adjacent pockets 232 is too narrow to

accommodate a deformation.

[0033] Fig. 12 illustrates a portion of yet another cage 320 for a conical rolling element bearing. Similar to the cages 20, 220 described above, the illustrated cage 320 includes a wall 324 having a first side 324A, a second side 324B, a first axial edge 328A, and a second axial edge 328B. In the illustrated construction, two deformations 366 are formed in communication with each pocket 332 to shorten the first axial edge 328A of the wall 324 relative to the second axial edge 328B. In other constructions, three or more deformations 326 may be formed in communication with each pocket 332.

[0034] Various features and advantages of the invention are set forth in the following claims.

Claims

CLAIMS What is claimed is:

1. A cage for a rolling element bearing, the cage comprising:

a generally ring-shaped wall defining an axis, the wall having a first axial edge and a second axial edge opposite the first axial edge; and

a circumferential row of spaced-apart openings formed in the wall and configured to receive a plurality of rolling elements;

wherein the wall is tapered toward at least one of the first axial edge and the second axial edge by a plurality of individual deformations formed in the wall.

2. The cage of claim 1, wherein the plurality of individual deformations is located around the wall proximate the at least one of the first axial edge and the second axial edge.

3. The cage of claim 1, wherein the wall is tapered toward only one of the first axial edge and the second axial edge by the plurality of individual deformations such that the cage is generally shaped as a truncated cone.

4. The cage of claim 1, wherein the wall is tapered toward both the first axial edge and the second axial edge by the plurality of individual deformations such that the cage is generally shaped as a truncated sphere.

5. The cage of claim 4, further comprising a second circumferential row of spaced-apart openings formed in the wall and configured to receive a second plurality of rolling elements.

6. The cage of claim 1, wherein each deformation is shaped to have an increasing amount of deformation in an axial direction toward the at least one of the first axial edge and the second axial edge.

7. The cage of claim 1, wherein each deformation is formed between two adjacent openings of the circumferential row of spaced-apart openings.

8. The cage of claim 1, wherein each deformation is formed in communication with a corresponding opening of the circumferential row of spaced apart openings.

9. The cage of claim 1, wherein each deformation is formed as a projection that projects from the wall generally toward the axis.

10. A method of manufacturing a tapered cage for a rolling element bearing, the method comprising:

providing a substantially flat strip having a first lengthwise edge, a second lengthwise edge opposite the first lengthwise edge, a first end, and a second end opposite the first end; forming a plurality of individual deformations along a length of the strip proximate at least one of the first and second lengthwise edges to impart a tapered ring shape into the strip, whereby the first end and the second end are adjacent each other;

forming a circumferential row of spaced-apart openings in the strip, each opening configured to receive a rolling element; and

coupling the first end and the second end together to form a unitary ring defining an axis, the first lengthwise edge becoming a first axial edge and the second lengthwise edge becoming a second axial edge of the unitary ring.

11. The method of claim 10, wherein the plurality of individual deformations are shaped to taper the unitary ring toward the first axial edge such that the cage is generally shaped as a truncated cone.

12. The method of claim 10, wherein the plurality of individual deformations are shaped to taper the unitary ring toward the first axial edge and toward the second axial edge such that the cage is generally shaped as a truncated sphere.

13. The method of claim 12, further comprising forming a second circumferential row of spaced-apart openings in the strip, each of the second circumferential row of spaced-apart openings configured to receive a second plurality of rolling elements.

14. The method of claim 10, wherein coupling the first end and the second end together includes welding the first end and the second end together.

15. The method of claim 10, wherein forming the circumferential row of spaced-apart openings in the strip occurs prior to forming the plurality of individual deformations along the length of the strip.

16. The method of claim 10, wherein forming the circumferential row of spaced-apart openings in the strip occurs after forming the plurality of individual deformations along the length of the strip and after coupling the first end and the second end together.

17. The method of claim 10, wherein forming the plurality of individual deformations includes forming the plurality of individual deformations sequentially by a press with a die set.

18. The method of claim 17, further comprising adjusting a male die of the die set to produce deformations of an alternate shape for a cage with an alternate taper shape.

19. The method of claim 10, wherein forming a plurality of individual deformations includes forming each deformation between two adjacent openings of the circumferential row of spaced-apart openings.

20. The method of claim 10, wherein forming a plurality of individual deformations includes forming each deformation in communication with a corresponding opening of the circumferential row of spaced-apart openings.

21. A method of manufacturing a tapered cage for a rolling element bearing, the method comprising:

providing a substantially flat strip having a first lengthwise edge, a second lengthwise edge opposite the first lengthwise edge, a first end, and a second end opposite the first end; deforming at least one of the first lengthwise edge and the second lengthwise edge along a length of the strip to impart a tapered ring shape into the strip, whereby the first end and the second end are adjacent each other;

22. The method of claim 21, wherein deforming at least one of the first lengthwise edge and the second lengthwise edge includes shortening the first lengthwise edge relative to the second lengthwise edge.

23. The method of claim 22, wherein shortening the first lengthwise edge includes forming a plurality of individual deformations along a length of the strip proximate the first lengthwise edge.

24. The method of claim 22, wherein deforming at least one of the first lengthwise edge and the second lengthwise edge further includes elongating the second lengthwise edge relative to the first lengthwise edge.