# US 11,028,880 B2 · Rolling bearing, rolling device, and method of manufacturing rolling device

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- Number: US 11,028,880 B2
- Document ID: US11028880B2
- Status: Granted
- Kind: B2
- Application number: 16/071,851
- Filed: 2017-01-05
- Published: 2020-12-24
- Granted: 2021-06-08
- Earliest claimed: 2016-01-21
- Assignees: Ntn Corporation
- Applicants: Ntn Corporation
- Inventors: Naoya Hasegawa
- Web page: https://patentgrep.com/patent/US11028880B2

## CPC

- F16C 33/62: Selection of substances
- F16C 33/64: Special methods of manufacture
- F16C 19/16: with a single row of balls
- F16C 33/32: Balls
- F16C 33/34: Rollers; Needles
- F16C 19/06: with a single row or balls
- F16C 19/26: with a single row of rollers
- F16C 19/364: {with tapered rollers, i.e. rollers having essentially the shape of a truncated cone}
- F16C 2202/04: Hardness
- F16C 2204/66: High carbon steel, i.e. carbon content above 0.8 wt%, e.g. through-hardenable steel
- F16C 2204/70: with chromium as the next major constituent
- F16C 2223/06: polishing
- F16C 2240/54: Surface roughness
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS

## Abstract

A rolling bearing, a rolling device, and a method of manufacturing the rolling device are provided, by which a long life can readily be implemented by suppressing surface damage even on the use condition that the oil film formation performance of a rolling part is poor. A rolling device includes: a first rolling component made of SUJ2; and a second rolling component made of SUJ2 and configured to contact the first rolling component. A surface of a rolling part of the first rolling component is greater in arithmetic mean roughness than a surface of a rolling part of the second rolling component. The arithmetic mean roughness of the surface of the rolling part of the second rolling component is 0.07 μm or more and 0.20 μm or less.

## Claims

### Claim 1

A rolling device comprising:
a first rolling component made of high carbon chromium bearing steel; and
a second rolling component made of high carbon chromium bearing steel and configured to contact the first rolling component,
wherein a surface of a rolling part of the first rolling component is greater in arithmetic mean roughness than a surface of a rolling part of the second rolling component, and the arithmetic mean roughness of the surface of the rolling part of the first rolling component is 0.70 μm or less,
wherein the arithmetic mean roughness of the surface of the rolling part of the second rolling component is 0.07 μm or more and 0.20 μm or less, and a root mean square slope of the surface of the rolling part of the second rolling component being 0.074 or more and 0.100 or less,
wherein the rolling part of the first rolling component is lower in Rockwell hardness than the rolling part of the second rolling component, and the Rockwell hardness of the rolling part of the second rolling component being 61.5 HRC or more,
wherein a film containing at least one of an iron oxide or an iron compound is provided on the surface of the rolling part of the first rolling component, and
wherein a value of an oil film parameter in a region between the first rolling component and the second rolling component is 1.2 or less.

### Claim 2 (depends on 1)

The rolling device according to claim 1, wherein the film contains a triiron tetraoxide.

### Claim 3 (depends on 1)

A rolling bearing as the rolling device according to claim 1, the rolling bearing comprising:
a plurality of rolling elements;
an outer ring having an outer ring raceway surface on an inner circumferential surface of the outer ring, the outer ring being disposed on an outside of the plurality of rolling elements so as to contact the plurality of rolling elements; and
an inner ring having an inner ring raceway surface on an outer circumferential surface of the inner ring, the inner ring being disposed on an inside of the plurality of rolling elements so as to contact the plurality of rolling elements,
the outer ring and the inner ring serving as the first rolling component, and the plurality of rolling elements serving as the second rolling component.

### Claim 4

A rolling device comprising:
a first rolling component made of high carbon chromium bearing steel; and
a second rolling component made of high carbon chromium bearing steel and configured to contact the first rolling component,
wherein a surface of a rolling part of the first rolling component is lower in Rockwell hardness than a surface of a rolling part of the second rolling component,
wherein the surface of the rolling part of the first rolling component is greater in arithmetic mean roughness than the surface of the rolling part of the second rolling component,
wherein the arithmetic mean roughness of the surface of the rolling part of the second rolling component is 0.07 μm or more and 0.10 μm or less, and a root mean square slope of the surface of the rolling part of the second rolling component being 0.07 or more and 0.10 or less, and
wherein a value of an oil film parameter in a region between the first rolling component and the second rolling component is 1.2 or less.

### Claim 5 (depends on 4)

The rolling device according to claim 4, wherein the Rockwell hardness of the surface of the rolling part of the first rolling component is lower, by 0.5 HRC or more, than the Rockwell hardness of the surface of the rolling part of the second rolling component.

### Claim 6 (depends on 4)

A rolling bearing as the rolling device according to claim 4, the rolling bearing comprising:
a plurality of rolling elements;
an outer ring having an outer ring raceway surface on an inner circumferential surface of the outer ring, the outer ring being disposed on an outside of the plurality of rolling elements so as to contact the plurality of rolling elements; and
an inner ring having an inner ring raceway surface on an outer circumferential surface of the inner ring, the inner ring being disposed on an inside of the plurality of rolling elements so as to contact the plurality of rolling elements,
the outer ring and the inner ring serving as the first rolling component, and the plurality of rolling elements serving as the second rolling component.