| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that a retainer made of a steel sheet often has an imperfect nitriding layer because the nitriding is carried out in the state that oxide existing on the surface of the retainer has not been completely removed, the nitriding layer can not satisfactorily hold lubricating oil, and the lubricating oil film is often broken because the nitriding layer has imperfect portions and the nitriding layer itself is inferior in smoothness, has cracks, etc. SOLUTION: In the retainer 1 for a bearing, the oxide existing on the surface of an annular sheet 1a formed by press working is removed by converting the oxide into a metal fluoride film by a fluorination treatment 12. The metal fluoride film prevents forming of the oxide, and the surface is fluorinated by surely removing the oxide from the surface. A nitriding layer N is closely, uniformly, and sufficiently formed on the surface of the annular sheet 1a. As a result, smoothness of the surface is maintained and the breakage of the oil film existing on the retainer 1 is prevented. The close, uniform, and smooth nitriding layer N can be stably formed. COPYRIGHT: (C)2005,JPO&NCIPI
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