| 摘要 |
PURPOSE:To reduce the manufacturing cost of precision parts for a wrist watch by lonnealing lead free-cutting steel as a starting material twice or more during drawing and after straightening so as to improve the toughness and hardness and to facilitate cutting. CONSTITUTION:When small-sized precision parts for a wrist watch are manufactured, free-cutting steel contg. 0.5-0.7wt% C and 0.10-0.30wt% Pb is lonnealed twice or more during drawing to <=1.5mm. diameter and after straightening. The steel is made tough and hard while maintaining the machinability, so the life of a cutting tool is not shortened. The working accuracy is improved because of the toughness and hardness, and precision parts can be manufactured at a low cost. |
