Bearing part and rolling bearing

Patent metadata

Field	Value
Publication number	US-10344801-B2
Application number	US-201715794841-A
Country	US
Kind code	B2
Filing date	Oct 26, 2017
Priority date	Feb 13, 2013
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

Each of an outer race ( 10 ), an inner race ( 11 ) and a ball ( 12 ) as a bearing part is a bearing part made of JIS standard SUJ2 and having a carbonitrided layer formed in a surface thereof, wherein, after heat treatment at a heating temperature of 500° C. for a retention time of one hour is performed, a Vickers hardness at a position with a depth of 0.02×T+0.175 (mm) from the surface is higher than a Vickers hardness at a core portion, which is a region where the carbonitrided layer is not formed in a thickness direction of the bearing part, by not less than 80 HV, where T represents the time of carbonitriding treatment for forming the carbonitrided layer.

First claim

The invention claimed is:

1. A bearing part made of JIS standard SUJ2 and having a carbonitrided layer with a nitrogen content of at least 0.4 mass % formed in an uppermost surface thereof exposed by a grinding by carbonitriding treatment for forming said carbonitrided layer and performing a heat treatment at a heating temperature of 500° C. for a retention time of one hour,
wherein, prior to said grinding to expose said uppermost surface, a Vickers hardness at a position with a depth of 0.02×T+0.175+t (mm) from an unground surface is higher than a Vickers hardness at a core portion, which is a region where said carbonitrided layer is not formed in a thickness direction of said bearing part, by not less than 80 HV, where T represents the time of said carbonitriding treatment and t (mm) represents a thickness of said bearing part removed by said grinding.

2. The bearing part according to claim 1 , wherein
the time of said carbonitriding treatment is not less than 4 hours and not more than 10 hours, and
said thickness is not more than 0.125 mm.

3. The bearing part according to claim 1 , wherein
the time of said carbonitriding treatment is not less than 6 hours and not more than 8 hours, and
said thickness is not more than 0.15 mm.

Assignees

• Ntn Toyo Bearing Co Ltd

Inventors

• Ohki Chikara

Classifications

• C22C38/44

  with molybdenum or tungsten · CPC title

• F16C33/32

  Balls · CPC title

• F16C33/34

  Rollers; Needles · CPC title

• C21D9/40

  for rings; for bearing races · CPC title

• C22C38/002

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title