| 摘要 |
PURPOSE:To obtain a gear having excellent resistance to pitching and strength of the dedendum to bending fatigue by combining a carburization heat treatment method of forming pseudospheroidal carbides on the surface of the gear of the steel having a specific compsn. and polishing of tooth surfaces after the heat treatment. CONSTITUTION:A gear made of a steel consisting, by weight, of 0.05-0.50% C, 0-0.80% Si, 0.40-2.0% Mn, 0-2.0% Mn, 1.0-2.5% Cr, 0-0.70% Mo and the balance Fe is heat treated by the carburization heat treatment method shown in the figure. A large amt. of pseudospheroidal carbides are formed in the above- mentioned way, whereafter the gear is subjected to a decarburization treatment and only the coarse carbides on the surface of the gear are removed. The treated steel is subjected to hardening directly or to reheating and hardening after air cooling. The gear is thereafter polished on the tooth faces. Since the deep carburization layer is obtd. according to the above-mentined method, a large amt. of carbides are obtd. on the tool surface even after the polishing, and since the coarse carbides on the dedendum surface are removed, the strength of the dedendum to bending fatigue is high. |
