Rolling bearing

Patent metadata

Field	Value
Publication number	US-9394583-B2
Application number	US-201514978528-A
Country	US
Kind code	B2
Filing date	Dec 22, 2015
Priority date	Oct 29, 2012
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

A rolling bearing in which at least one of the bearing rings is obtained by applying a induction heat treatment to a spheroidizing annealed steel material having a DI value of 1.0 or more to form a hardened layer having a hardness of 550 HV or more on at least a raceway surface and a fitting surface. In the induction heat-treated bearing ring, (A) an average retained austenite amount is 12 vol % or less, (B) the raceway surface has a retained austenite amount of 12 vol % or more and a residual compressive stress of −100 MPa or less, and (C) a difference between a hardness of the raceway surface and a minimum hardness of a region having a hardness of less than 550 HV is 150 HV or more.

First claim

The invention claimed is:

1. A rolling bearing comprising one or more parts of a pair of bearing rings and a rolling element, wherein:
at least one of the bearing rings is obtained by applying a induction heat treatment to a spheroidizing annealed steel material having a DI value represented by the following formula (1) of 1.0 or more to form a hardened layer having a hardness of 550 HV or more on at least a raceway surface and a fitting surface, and
in the induction heat-treated bearing ring, the raceway surface has a retained austenite amount of 12 vol % or more, and a difference between a hardness of the raceway surface and a minimum hardness of a region having a hardness of less than 550 HV is 150 HV or more,
DI=D 0× f Si× f Mn× f Ni× f Cr× f Mo  (1)

D0=0.2×(C)+0.14
fSi=1+0.64×(Si)
fMn=1+4.1×(Mn)
fNi=1+0.52×(Ni)
fCr=1+2.33×(Cr)
fMo=1+3.14×(Mo)
where (C), (Si), (Mn), (Ni), (Cr) and (Mo) are contents (mass %) of respective elements in the steel material.

2. The rolling bearing according to claim 1 ,
wherein the steel material contains from 0.7 to 1.1 mass % of C, from 0.15 to 0.7 mass % of Si, from 0.01 to 1.15 mass % of Mn, from 0.9 to 1.6 mass % of Cr, from 0 to 2.0 mass % of Mo, and from 0 to 2.0 mass % of Ni, with the balance being iron and unavoidable impurities.

3. The rolling bearing according to claim 2 ,
wherein an average retained austenite amount is 12 vol % or less.

4. The rolling bearing according to claim 2 ,
wherein a residual compressive stress of −100 MPa or less.

5. The rolling bearing according to claim 1 ,
wherein when, in the raceway surface of the induction heat-treated bearing ring, a depth of the region having the hardness of 550 HV or more is Y 0 (mm), an average thickness of a region coming into contact with the rolling element is T (mm), a thickness of the region having the hardness of less than 550 HV is W (mm), in an opposite-raceway surface a depth of a region having a hardness of 550 HV or more is Y 0 ′ (mm), and a diameter of the rolling element is D W (mm), the rolling bearing satisfies all of
(a) Y 0 ≧0.07D W
(b) Y 0 >Y 0 ′
(c) Y 0 /T≦ 30%
(d) W/T≧55%.

6. The rolling bearing according to claim 5 ,
wherein an average retained austenite amount is 12 vol % or less.

7. The rolling bearing according to claim 5 ,
wherein a residual compressive stress of −100 MPa or less.

8. The rolling bearing according to claim 2 ,
wherein when, in the raceway surface of the induction heat-treated bearing ring, a depth of the region having the hardness of 550 HV or more is Y 0 (mm), an average thickness of a region coming into contact with the rolling element is T (mm), a thickness of the region having the hardness of less than 550 HV is W (mm), in an opposite-raceway surface a depth of a region having a hardness of 550 HV or more is Y 0 ′ (mm), and a diameter of the rolling element is D W (mm), the rolling bearing satisfies all of
(a) Y 0 ≧0.07D W
(b) Y 0 >Y 0 ′
(c) Y 0 /T≦ 30%
(d) W/T≧55%.

9. The rolling bearing according to claim 1 ,
wherein an average retained austenite amount is 12 vol % or less.

10. The rolling bearing according to claim 1 ,
wherein a residual compressive stress of −100 MPa or less.

Assignees

• Nsk Ltd

Inventors

• Hidaka Hideyuki
• Watanuki Daisuke
• Tamura Kazuki

Classifications

• F16C2202/04

  Hardness · CPC title

• C22C38/44

  with molybdenum or tungsten · CPC title

• F16C19/364

  with tapered rollers, i.e. rollers having essentially the shape of a truncated cone · CPC title

• F16C19/06

  with a single row or balls · CPC title

• F16C33/64

  Special methods of manufacture · CPC title