| 摘要 |
PROBLEM TO BE SOLVED: To improve silence, impact and vibration in transportation or fretting durability in working an apparatus, improve acoustic durability due to pre-load extraction and dust suction taken notice of on a hybrid bearing and prevent a deterioration with the lapse of time after finishing work in high precision and leaving it at high temperature and acoustic deterioration under severe using condition. SOLUTION: A nitriding layer of not less than Hv 900 made of a compound layer and a diffusion hardening layer by nitriding is formed on a surface of a rolling element made of a steel material. The nitriding layer is homogenized by making sphericity and diametrical size variation of the rolling element not more than 0.05μm and surface roughness not more than 0.003μmRa. Impact resistance and fretting durability are improved by making thickness of the compound layer in the nitriding layer not less than 3μm and its average thickness not more than 2% of a diameter Da of the rolling element. Durability is improved by stabilizing the nitriding layer by manufacturing the rolling element of steel for a bearing, working it in a half-worked sphere of not more than sphericity 3.0μm after quenching and tempering and furthermore and continuously nitriding it at not more than 480 deg.C and finishing it. |
