| 摘要 |
PROBLEM TO BE SOLVED: To improve the rolling fatigue life of a bearing for supporting a ball screw. SOLUTION: An inner ring 12, an outer ring 13, and a ball 14 are each composed of steel comprising, by weight, 0.4 to 0.8 C, 0.4 to 0.9% Si, 0.7 to 1.3% Mn and≤0.5% C, and, preferably comprising≤0.3% Cr, and the balance Fe with inevitable impurities, and a carbonitrided layer S having a retained austenite content of 20 to 40% and a Rockwell hardness HRC of≥58 is formed on the surface of these parts. COPYRIGHT: (C)2008,JPO&INPIT
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