BEARING CAGE FOR A ROLLING-ELEMENT BEARING

Abstract

First and second bearing cage halves each having an annular base body and a plurality of pins extending from the base body and a plurality of pin receptacles, the first and second cage haves forming a bearing cage when the pins are received into the pin receptacles. A body of sacrificial material is located on the pins and/or in the pin receptacles which body is configured to be melted ultrasonically to join the first cage half to the second cage half and form the bearing cage.

Claims

1. A system comprising: a first cage half and a second cage half configured to be ultrasonically welded to the first cage half to form a bearing cage for a rolling-element bearing, the first cage half and the second cage half each comprising an annular base body, a plurality of pins extending axially from the annular base body, and a plurality of pin receptacles complementary to the plurality of pins, wherein the plurality of pins of the first cage half are configured to extend into the plurality of pin receptacles of the second cage half and the plurality of pins of the second cage half are configured to extend into the plurality of pin receptacles of the first cage half to form bearing cage bridges and pockets configured to receive a rolling element, and wherein the pins of the first cage half and/or the pins of the second cage half and/or the pin receptacles of the first cage half and/or the pin receptacle of the second cage half include a body of sacrificial material configured to be ultrasonically melted to connect the first cage half to the second cage half to form the bearing cage.

2. The system according to claim 1, wherein the first cage half is configured identically to the second cage half.

3. The system according to claim 1, wherein each pin receptacle includes a radially outer, axially extending ring section configured to radially outwardly support each pin in the each pin receptacle.

4. The system according to claim 3, wherein the axially extending ring section is formed over the ring-shaped base body of the cage half.

5. The system according to claim 3, wherein each pin includes a radially outer step that interacts with the ring section of the pin receptacle such that the cage bridges formed by the each pin and the each pin receptacle have a homogeneous outer surface.

6. The system according to claim 1, wherein each pocket has a toroidal geometry comprising a radially inner spherical portion and an radially outer cylindrical portion.

7. The system according to claim 1, wherein the first cage half and the second cage half are each manufactured from a material selected from a group consisting of PEEK and PA4.6, and PA6.6, the material having a carbon fiber content of 15%-30% or a glass fiber content of 15%-30%.

8. The system according to claim 1, wherein the sacrificial material is wedge-shaped, pyramid-shaped, or conical.

9. The system according to claim 1, wherein the first cage half includes at least one primary contact surface that abuts against a secondary contact surface of the second cage half in order to conduct ultrasound into the contact surfaces and/or into the sacrificial material.

10. The system according to claim 1, wherein the first cage half and/or the second cage half includes a secondary contact surface that opposes a primary contact surface and is configured to conduct ultrasound into the contacting surfaces and/or into the sacrificial material.

11. The system according to claim 10, wherein the cage bridges each form a wedge-shaped surface that is configured to conduct ultrasound from the secondary contact surface to the contacting surfaces.

12. The system according to claim 1, wherein each pin receptacle includes a portion configured to radially overlie a portion of each pin when the each pin is inserted into the each pin receptacle.

13. A bearing cage comprising the first cage half and the second cage half according to claim 1 ultrasonically welded together.

14. The system according to claim 1, wherein the first cage half is configured identically to the second cage half, wherein the plurality of pins of the first cage half each include an axial end wall, wherein the plurality of pin receptacles of the second cage half each include an axial end wall, and wherein the bodies of sacrificial material are located axially between the axial end walls of the pins of the first cage half and the axial end walls of the receptacles of the second cage half when the plurality of pins of the first cage half are located in the plurality of cage receptacles of the second cage half.

15. The system according to claim 14, wherein each of the pins of the first cage half has a hollow interior delimited at one axial end by the axial end wall of the each pin, the hollow interiors being axially open at an axially outer edge of the first cage half.

16. The system according to claim 15, wherein each pin receptacle of the second cage half includes an axially extending support wall configured to radially overlie the axial end wall of the pin received in the each pin receptacle.

17. A bearing cage comprising the first cage half and the second cage half according to claim ultrasonically welded together.

18. An ultrasonic welding device that is adapted to the shape of the system according to claim 1 and that is configured to apply ultrasound to the first cage half and to the second cage half to form the bearing cage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a schematic perspective view of a two-part bearing cage.

[0024] FIG. 2 is a schematic detail view of the first cage half.

[0025] FIG. 3 is a schematic detail view of the second cage half.

[0026] FIG. 4 is a first exemplary embodiment of the sacrificial material of FIGS. 2 and 3.

[0027] FIG. 5 is a second exemplary embodiment of the sacrificial material of FIGS. 2 and 3.

[0028] FIG. 6 is a third exemplary embodiment of the sacrificial material of FIGS. 2 and 3.

[0029] FIG. 7 is a schematic representation of the assembly of the two cage halves.

[0030] FIG. 8 is a further schematic representation of the assembly of the two cage halves.

[0031] FIG. 9 is a further schematic representation of the assembly of the two cage halves.

[0032] FIG. 10 is a schematic detail view of the cage halves including contact surfaces for the ultrasonic welding device.

[0033] FIG. 11 is a further schematic detail view of the cage halves including contact surfaces for the ultrasonic welding device.

[0034] FIG. 12 is a further schematic detail view of the cage halves including contact surfaces for the ultrasonic welding device.

[0035] FIG. 13 is a further schematic detail view of the cage halves including contact surfaces for the ultrasonic welding device.

[0036] FIG. 14 is a schematic perspective view of a retaining device for an ultrasonic welding device.

[0037] FIG. 15 is a schematic perspective view of the retaining device of FIG. 14 including an assembled bearing cage.

[0038] FIG. 16 is a sectional view of FIG. 15.

DETAILED DESCRIPTION

[0039] In the following, identical or functionally equivalent elements are designated by the same reference numbers.

[0040] FIG. 1 shows a schematic spatial view of a bearing cage for a ball bearing 1 that is formed from a first bearing cage half 100 and a second bearing cage half 200. Here the bearing cage halves 100 and 200 are configured identically. As can be further seen from FIG. 1, the bearing cage 1 includes bridges 2 that form cage pockets 4 between them, wherein rolling elements (not depicted) are receivable. Here the cage pockets 4 have a toroidal shape; this means that the cage pockets 4 are configured spherical on their radially inner side 4-1, while they are configured cylindrical on their radially outer side 4-2. This toroidal design makes it possible that the rolling elements, i.e., the balls, are well guided by the radially inner region 4-1 and are entirely enclosed in the pockets 4, while on their radially outer region 4-2 they have a spacing to the bearing cage 1 such that lubricant can penetrate into the gap between rolling element and bearing cage 1, whereby a particularly good lubricating of the balls is made possible. Furthermore it can be seen from FIG. 1 that the cage bridge 2 formed by the pins 6-1, 6-2 engaging into corresponding pin receptacles 8-1, 8-2 of the respective cage halves 100, 200. The engagement of the pins 6-1, 6-2 into the pin receptacles 8-2, 8-1 is configured here such that both a radial and an axial fixing of the cage halves 100, 200 is possible.

[0041] Each cage half 100 includes an annular base body 10 from which the pins 6 extend, and in which the pin receptacles 8 are formed. Here each pin receptacle 8 includes an axially extending ring section 12 that extends axially over the pin 6 when a pin 6 is received in the receptacle 8 and thus supports the pin 6 radially outward. This axial ring section 12 prevents the cage pins 6 from bending radially outward and contact a bearing ring adjacent to the bearing cage 1 even under high centrifugal forces, which could lead to increased friction and to a premature bearing failure. Furthermore it can be seen in FIGS. 2 and 3 that the ring section 12 is formed integrally with the annular base body 10. The radial forces can thereby be supported and diverted into the base body 10 so that even with high radial loads a bending-open of the cage 1 does not occur.

[0042] In order to achieve a particularly good engagement and, as depicted, for example, in FIG. 1, a homogeneous outer surface 14 on the bearing cage 100, the pin 6 includes a gradation (step) 16 that interacts with the ring section 12. The design of pin 6 and pin receptacle 8 can also be seen in enlarged sections of FIGS. 2 to 6.

[0043] FIG. 2 shows a schematic view of a cage half 100, 200. In order to be able to correctly assemble the two cage half 100, 200, a side surface 18 is provided on the pin receptacle 8, which side surface 18 serves as a centering surface for the corresponding pin 6. The pin receptacle 8 includes a further centering surface 20 that also serves for the correct insertion of the pin 6. Corresponding stop surfaces 22, 24 are provided on the pin receptacles 8 and the pins 6. In addition to the gradations 16, these stop surfaces 22, 24 prevent the two cage halves 100, 200 from being pushed together too far such that they abut against each other at the stop surfaces 22, 24. In this way sufficient space is provided in the cage 1 for the balls.

[0044] Sacrificial material 28 is provided on the pins 6 or the pin receptacles 8 or both that is melted by ultrasound after assembling the cage halves 100, 200. Here the sacrificial material is provided on surfaces of the pins 6 and/or of the pin receptacles 8, which surfaces contact each other in the assembled state. The sacrificial material can have various shapes, such as, for example, wedge-shaped (see FIG. 4), conical (see FIG. 5) or also be pyramid-shaped or spherical. Instead of providing the sacrificial material on the pin 6, as is shown in FIGS. 4 and 5, the sacrificial material can also be provided in the pin receptacle 8, as is depicted in FIG. 6. Furthermore, the sacrificial material can be provided both on the pins 6 and in the pin receptacles 8.

[0045] In FIGS. 7 to 9 the assembly of the two cage halves 100, 20 is now described. During assembly of the two symmetrical cage halves 100, 200, they are aligned in the radial direction with the aid of the centering surface 19, and in the circumferential direction by the surfaces 20, 26. This has the advantage that possible distortions, deformations, or dimensional deviations caused by the manufacturing process of the cage half 100, 200 can thereby be compensated for.

[0046] During the assembling of the two cage halves 100, 200, a gap of a plurality of millimeters remains between the two cage halves. If the sacrificial material 28 is melted by the ultrasonic welding, the sacrificial material 28 flows into the connecting surface 30, 32, 34 (see FIG. 9). A possible clearance between the cage halves 100, 200, which can arise due to manufacturing tolerances, can thereby be eliminated. During the operation of the bearing, relative movements can therefore no longer arise that would lead to damage of the cage 1.

[0047] The stop surfaces 22, 24 define the axial spacing of the cage halves. Since the axial spacing is defined via these surfaces, a constant width of the ball pockets 4 can be ensured. A minimum width cannot thereby not be fallen below, so that during the assembly or in operation of the bearing the balls cannot jam in the pocket. Such a jamming could arise due to different temperature-induced expansions of the different materials, for example, with balls made of steel or ceramic and a plastic cage. Furthermore, a possible gap in the pockets 4 can also be avoided by the axial stop via the stop surfaces 22, 24, which possible gap in the pockets 4 would cause negative properties in operation. Such a gap could lead to a cage or ball wear and have negative effects on the lubricating film.

[0048] In FIGS. 10 to 13, contact surfaces 36, 38, 42 are depicted for conducting ultrasound to the pins 6 or pin receptacles 8 and the corresponding sacrificial material 28. The ultrasonic welding device can include a primary contact surface 36 and two secondary contact surfaces 38 per cage bridge. Here the primary contact surface 36 abuts directly against the sacrificial material 28. This is shown, for example, in FIG. 13: here the primary contact surface 36 lies opposite the pin receptacle 8. In this way, ultrasound can be introduced directly into the sacrificial material 28. The primary contact surface 36 thus provides that the ultrasound is introduced directly into the surface including the sacrificial material 28 or an opposing surface.

[0049] In addition, ultrasound is introduced via adjacent surfaces 38 and is also conducted to the sacrificial material 28 via the wedge-shaped cage bridge half 40. Here the cage 1 can preferably include fiber components in the plastic, in particular carbon-fiber components, that help to effectively conduct the ultrasound to the sacrificial material 28. Due to the primary and secondary contact surfaces 36, 38 and the cage bridge half 40, it is possible to conduct ultrasound to the pin receptacles 8 or the opposing surfaces, and the pins 6 or the opposing surfaces, so that the sacrificial material 28 is melted particularly well.

[0050] In some embodiments of the cage 1, the ultrasonic welding device can be extended up to a further primary contact surface 42 that is located in the pins 6. This is useful in particular in wider variants of the cage 1, since with increasing spacing of the two weld points per cage pocket bridge, the ultrasound cannot carry forward sufficiently. This can be prevented by the further primary contact surface 42.

[0051] FIGS. 14 to 16 show a retaining device 300 of an ultrasonic welding device. The retaining device 300 shows a negative shape 44 of the cage rear side. The negative shape 44 has the corresponding number of ball pockets, a support surface 46 for the bearing inner ring, and a centering device 48 for the bearing inner ring. Here the negative shape 44 is configured such that the rear surfaces of the pin receptacles 8 and of the pins 6 are primarily supported, since these surfaces must support the force exerted during ultrasonic welding. Furthermore, a rotating of the cage half 100, 200 about the axis of rotation of the bearing will be prevented in order to achieve a high positional accuracy during ultrasonic welding. This is also achieved by the negative shape 44 and the support surfaces 46, 48.

[0052] The support surface 46 supports the bearing inner ring in the vertical direction during the ultrasonic welding. In addition, the centering device 48 for the bearing inner ring positions it such that it cannot collide with the ultrasonic welding device due to the cage clearance. Further support surfaces 50, 52 are provided for the cage, wherein the vertical spacing of the support surfaces 50, 52 to the support surface 46 is configured such that an encircling gap 56 exists between the rolling elements and the cage halves 100, 200. This will prevent the rolling elements from being in direct contact with the oscillating components, i.e., the cage halves 100, 200 and the ultrasonic welding device, in order to thus prevent damage of the bearing during the ultrasonic welding device process.

[0053] Only the bearing inner ring 58 abuts on the support surface 46. The bearing outer ring 60 is not supported in the vertical direction. During the ultrasonic welding a sufficiently large preload force 62 is exerted on the bearing outer ring 60 in the vertical direction toward the support surface 46, whereby the bearing components, bearing outer ring 60, rolling elements 54, and bearing inner ring 58, are clamped to each other. Due to this clamping, no relative movements can arise between the bearing components during the welding process, which relative movements would cause damage in the bearing.

[0054] In summary, a simple manufacturing of a bearing cage by ultrasonic welding is disclosed, wherein the resulting cage ensures a secure retaining of the two cage halves even at high rotational speeds. For this purpose the pins and/or the pin receptacles include a sacrificial material on surfaces respectively contacting them, which sacrificial material is melted by the action of ultrasound and subsequently connects the two cage halves.

[0055] Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved two-part bearing cages.

[0056] Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

[0057] All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

REFERENCE NUMBER LIST

[0058] 1 Bearing cage [0059] 2 Bridge [0060] 4 Cage pockets [0061] 6 Pin [0062] 8 Pin receptacle [0063] 10 Base body [0064] 12 Axially extending ring section [0065] 14 Homogeneous outer surface [0066] 16 Gradation (step) [0067] 18, 19, 20 Centering surface [0068] 22,24 Stop surface [0069] 26 Centering surface [0070] 28 Sacrificial material [0071] 30, 32, 34 Connecting surface [0072] 36 Primary contact surface [0073] 38 Secondary contact surface [0074] 40 Cage bridge half [0075] 42 Primary contact surface [0076] 44 Negative shape [0077] 46 Support surface [0078] 48 Centering [0079] 50 Support surface [0080] 52 Support surface [0081] 54 Balls [0082] 56 Gap [0083] 58 Inner ring [0084] 60 Outer ring [0085] 62 Preload force [0086] 100 First cage half [0087] 200 Second cage half [0088] 300 Retaining device