| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a pinion shaft and a planetary gear device having a long lifetime even when they are used at a high-speed rotation under a high-temperature condition. <P>SOLUTION: The pinion shaft 5 for rotatably supporting a pinion gear 3 of the planetary gear device is fixed to a carrier 4 by caulking. The pinion shaft 5 is formed of a high-carbon chromium bearing steel. The pinion shaft is subjected to the nitriding and the annealing at the temperature higher than the temperature for the nitriding, and only a portion forming a rolling surface out of an outer circumferential surface of the pinion shaft 5 is subjected to the induction hardening. The nitrogen concentration of a surface layer part of the pinion shaft 5 is≥0.05 mass%, and≤0.6 mass%, and the amount of the residual austenite is≥15 vol.% and≤30 vol.%. The surface hardness of the portion forming the rolling surface is≥700 Hv, and the surface hardness of an end in the longitudinal direction is≤300 Hv. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
