| 摘要 |
PROBLEM TO BE SOLVED: To improve a peeling damage life without any increase in manufacturing cost so as to prolong the life of a bearing as a whole by setting surface roughness of a steel ball within a predetermined range. SOLUTION: The subject steel ball is used under a condition in which foreign matter may be intruded, and its surface roughness is set to be 0.02-0.2μm. Peeling is caused by priority in a smooth face because of rolling between a rough surface and a smooth surface, and peeling damage is caused because of interference with the surface projection of the rough surface of a counterpart. Therefore, when a race surface is roughened because of biting of the foreign matter, generation of peeling damage can be delayed if surface roughness of a steel ball is slightly increased for smoothing the rough surface of the race. An indentation due to the foreign matter is several tensμm in depth and severalμm in height of a swell in the circumference. Considering that the circumferential swell works as a projection, mutual swells abrade each other when the steel ball whose surface roughness is in the same level as the swell is used, so that peeling generation life can be prolonged.
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