| 摘要 |
PROBLEM TO BE SOLVED: To provide a pinion shaft having a long service life even if it is used at a high rotation under a high temperature, and an inexpensive planetary gear device having a long service life even if it is used at a high rotation under a high temperature. SOLUTION: This pinion shaft 5 rotatably supporting a pinion gear 3 meshed with a sun gear 1 and a ring gear 2 of the planetary gear device is composed of an alloyed steel with 0.5 to 1.2 mass % of carbon, 0.5 to 2.5 mass % of chromium, 0.6 to 1.5 mass % of silicon, 0.15 to 1.5 mass % of manganese, and 3.0 mass % or less of molybdenum, and 12 ppm of oxygen and the balance being iron and inevitable impurity. The shaft 5 is subjected to nitriding, induction hardening and tempering only for the rolling surface, and making the concentration of nitrogen of the surface 0.05 to 0.6 mass % and the amount of the remaining austenite 3 volume % or less. The pinion shaft 5 is then fixed to a carrier 4 by caulking. COPYRIGHT: (C)2004,JPO |
