Sintered bearing and manufacturing process therefor

Patent metadata

Field	Value
Publication number	US-2016223016-A1
Application number	US-201415026134-A
Country	US
Kind code	A1
Filing date	Oct 2, 2014
Priority date	Oct 3, 2013
Publication date	Aug 4, 2016
Grant date	—

Abstract

A sintered bearing ( 1 ) contains as main components iron, copper, a metal having a lower melting point than copper, and a solid lubricant. The sintered bearing ( 1 ) includes a surface layer (S 1 ) and a base part (S 2 ). The surface layer (S 1 ) is formed mainly of flat copper powder arranged so as to be thinned in a thickness direction. In the base part (S 2 ), an iron structure ( 33 ) and a copper structure ( 31 c ) brought into contact with the iron structure are formed of partially diffusion-alloyed powder in which copper powder is partially diffused in iron powder. Thus, a sintered bearing which achieves a balance between wear resistance of a bearing surface and strength of the bearing, and realizes low cost can be provided.

First claim

1 . A sintered bearing, which contains as main components iron, copper, a metal having a lower melting point than copper, and a solid lubricant,
the sintered bearing comprising:
a base part containing an iron structure and a copper structure; and
a surface layer covering a surface of the base part,
wherein: the surface layer is formed mainly of flat copper powder arranged so as to be thinned in a thickness direction; and at least part of the iron structure and the copper structure in the base part is formed of partially diffusion-alloyed powder in which copper powder is partially diffused in iron powder.

2 . The sintered bearing according to claim 1 , wherein the copper structure is formed in a surface of the surface layer at an area ratio of 60% or more.

3 . The sintered bearing according to claim 1 , wherein the iron structure and the copper structure in the base part are entirely formed of the partially diffusion-alloyed powder.

4 . The sintered bearing according to claim 1 , wherein the iron structure and the copper structure in the base part are formed of: the partially diffusion-alloyed powder; and any one or both of elemental iron powder and elemental copper powder.

5 . The sintered bearing according to claim 1 , wherein, in the base part, the copper structure brought into contact with the iron structure comprises a structure in which the low-melting point metal is diffused in the copper powder.

6 . The sintered bearing according to claim 1 , wherein the sintered bearing contains the low-melting point metal at a weight ratio of 10 wt % or more and 30 wt % or less with respect to the flat copper powder.

7 . The sintered bearing according to claim 1 , wherein the solid lubricant comprises graphite.

8 . The sintered bearing according to claim 1 , wherein the iron structure is formed of a ferrite phase.

9 . The sintered bearing according to claim 1 , wherein the iron structure is formed of a ferrite phase and a pearlite phase that is present at a grain boundary of the ferrite phase.

10 . The sintered bearing according to claim 1 , wherein the partially diffusion-alloyed powder has a ratio of copper of 10 wt % or more and 30 wt % or less.

11 . The sintered bearing according to claim 1 , wherein the sintered bearing is impregnated with a lubricating oil having a kinematic viscosity of 30 mm 2 /sec or more and 200 mm 2 /sec or less.

12 . The sintered bearing according to claim 1 , wherein the sintered bearing is used for a starter configured to activate an engine.

13 . The sintered bearing according to claim 1 , wherein the sintered bearing is used for a vibration motor.

14 . A method of manufacturing a sintered bearing, the method comprising:
mixing partially diffusion-alloyed powder in which copper powder is partially diffused in iron powder, flat copper powder, metal powder having a lower melting point than copper, and solid lubricant powder; forming a green compact with the resultant mixed powder; and sintering the green compact at a temperature lower than a melting point of copper.

15 . The sintered bearing according to claim 2 , wherein the iron structure and the copper structure in the base part are entirely formed of the partially diffusion-alloyed powder.

16 . The sintered bearing according to claim 2 , wherein the iron structure and the copper structure in the base part are formed of: the partially diffusion-alloyed powder; and any one or both of elemental iron powder and elemental copper powder.

17 . The sintered bearing according to claim 2 , wherein, in the base part, the copper structure brought into contact with the iron structure comprises a structure in which the low-melting point metal is diffused in the copper powder.

18 . The sintered bearing according to claim 3 , wherein, in the base part, the copper structure brought into contact with the iron structure comprises a structure in which the low-melting point metal is diffused in the copper powder.

19 . The sintered bearing according to claim 4 , wherein, in the base part, the copper structure brought into contact with the iron structure comprises a structure in which the low-melting point metal is diffused in the copper powder.

20 . The sintered bearing according to claim 15 , wherein, in the base part, the copper structure brought into contact with the iron structure comprises a structure in which the low-melting point metal is diffused in the copper powder.

Assignees

• Ito Yoshinori
• Yamashita Tomonori
• Ntn Toyo Bearing Co Ltd

Inventors

• Ito Yoshinori
• Yamashita Tomonori

Classifications

• F16C2204/10

  Alloys based on copper · CPC title

• F16C2204/60

  Ferrous alloys, e.g. steel alloys · CPC title

• F16C2223/42

  by spraying the coating material, e.g. plasma spraying · CPC title

• F16C23/041

  with edge relief · CPC title

• F16C33/14

  Special methods of manufacture; Running-in · CPC title