| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a coil spring which is capable of improving the fatigue strength. <P>SOLUTION: A spring element wire is subjected to a warm shot-peening step S4, a water-cooling step S5, and a cold shot-peening step S7. In the warm shot-peening step S4, shots are projected while the spring element wire after the tempering is in the warm zone exceeding 100°C, and the compressive residual stress is generated to the deep position from the surface of the spring element wire. At least the surface of the spring element wire is cooled to the temperature of <100°C by the water-cooling step S5 to be executed after the warm shot-peening S4. In the cold shot-peening step S7 to be executed after the water-cooling step S5, shots of the same size as that of shots in the warm shot-peening step S4 are projected onto the spring element wire, the surface roughness of the spring elements wire is reduced, and, in particular, the compressive residual stress in the vicinity of the surface of the wire increases. <P>COPYRIGHT: (C)2012,JPO&INPIT |
