Cage and rolling bearing

Patent metadata

Field	Value
Publication number	US-9284982-B2
Application number	US-201113583915-A
Country	US
Kind code	B2
Filing date	Mar 9, 2011
Priority date	Mar 10, 2010
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

A cage is made of a magnesium alloy such as AZ91D, and is molded by means of injection molding. In this cage, a confluence region is brought away to outside the cage during the injection molding. The confluence region is a region including a void formed by merging of flows of the magnesium alloy. When observing a cross sectional surface of the cage, a ratio of an α phase having a grain size of 20 μm or greater is less than 15% in the magnesium alloy constituting the cage.

First claim

The invention claimed is:

1. A cage holding a rolling element in a rolling bearing, comprising:
the cage being made of a magnesium alloy,
the cage being molded by injection molding,
the cage not having a confluence region including a void formed by merging of flows of said magnesium alloy in a completely molten state,
wherein in a cross sectional surface of the cage, an area ratio of an α phase having a grain size of 20 μm or greater being less than 15% in said magnesium alloy,
wherein a ratio of tensile strength in a weld portion of the cage to tensile strength in a portion other than said weld portion is 0.8 or greater, said weld portion being formed at a region at which the flows of said magnesium alloy are merged during said injection molding.

2. The cage according to claim 1 , wherein when observing the cross sectional surface of the cage, the ratio of the α phase having a grain size of 20 μm or greater is less than 5% in said magnesium alloy.

3. The cage according to claim 1 , wherein when observing the cross sectional surface of the cage, no α phase having a grain size of 20 μm or greater is contained in said magnesium alloy.

4. The cage according to claim 1 , wherein the cage is comb-shaped.

5. The cage according to claim 1 , wherein the cage has a surface provided with a cation electrodeposition coating layer having a thickness of 15 μm or smaller.

6. The cage according to claim 1 , wherein said magnesium alloy constituting the cage has an average crystal grain size of 10 μm or smaller.

7. The cage according to claim 1 , wherein said magnesium alloy constituting the cage has an average crystal grain size of 5 μm or smaller.

8. The cage according to claim 1 , wherein said magnesium alloy constituting the cage is age hardened.

9. A rolling bearing comprising:
a raceway member;
a plurality of rolling elements arranged in contact with said raceway member; and
a cage rollably holding said rolling elements,
the cage being the cage recited in claim 1 .

10. The rolling bearing according to claim 9 , wherein the rolling bearing is used to rotatably support a main shaft of a machine tool relative to a member disposed opposite to said main shaft.

11. A cage holding a rolling element in a rolling bearing, comprising:
the cage being made of a magnesium alloy,
the cage being molded by injection molding,
the cage not having a confluence region including a void formed by merging of flows of said magnesium alloy including a liquid phase,
wherein in a cross sectional surface of the cage, an area ratio of an α phase having a grain size of 20 μm or greater being less than 15% in said magnesium alloy, and
wherein the cage has a surface provided with an anodized layer having a thickness of 15 μm or smaller.

12. The cage according to claim 11 , wherein when observing the cross sectional surface of the cage, the ratio of the α phase having a grain size of 20 μm or greater is less than 5% in said magnesium alloy.

13. The cage according to claim 11 , wherein when observing the cross sectional surface of the cage, no α phase having a grain size of 20 μm or greater is contained in said magnesium alloy.

14. The cage according to claim 11 , wherein the cage is comb-shaped.

15. The cage according to claim 11 , wherein said magnesium alloy constituting the cage has an average crystal grain size of 10 μm or smaller.

16. The cage according to claim 11 , wherein said magnesium alloy constituting the cage has an average crystal grain size of 5 μm or smaller.

17. The cage according to claim 11 , wherein said magnesium alloy constituting the cage is age hardened.

18. A rolling bearing comprising:
a raceway member;
a plurality of rolling elements arranged in contact with said raceway member; and
a cage rollably holding said rolling elements,
the cage being the cage recited in claim 11 .

19. The rolling bearing according to claim 18 , wherein the rolling bearing is used to rotatably support a main shaft of a machine tool relative to a member disposed opposite to said main shaft.

Assignees

• Kawamura Mitsuo
• Shimazu Eiichiro
• Hayakawa Yasutake
• Okuno Takahiro
• Ooshimo Junichi
• Sakamoto Ryuichi
• Ntn Toyo Bearing Co Ltd

Inventors

• Kawamura Mitsuo
• Shimazu Eiichiro
• Hayakawa Yasutake
• Okuno Takahiro
• Ooshimo Junichi
• Sakamoto Ryuichi

Classifications

• F16C33/44

  Selection of substances (F16C33/40, F16C33/41 take precedence) · CPC title

• F16C2220/04

  by injection-moulding · CPC title

• F16C2204/26

  Alloys based on magnesium · CPC title

• F16C33/414 Primary

  formed as one-piece cages, i.e. monoblock comb cages · CPC title

• F16C33/445

  Coatings · CPC title