| 摘要 |
PROBLEM TO BE SOLVED: To provide a shot peening process capable of most efficiently improving durability of a sprint in consideration of an operating condition to be actually practiced. SOLUTION: Ceramic beads are projected on the spring at speed of not more than 50 m/s. Otherwise, it is possible to apply a method to adjust a shot peening condition to satisfy an expression [σR>=2.675×HS-955] against hardness HS of the spring by compression residual stressσR of a surface after shot peening. In these cases, it is desirable to use the ceramic beads an average grain diameter of which is not more than 0.3 mm. Additionally, either one of the above methods is carried out in the last shot peening in the case of applying a plurality number of the shot peening. In this case, it is desirable to carry out the shot peening except for the last shot peening under a conventional method (to project steel shot grains of about 0.1-1.2 mm in diameter at speed of 60-90 m/s).
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