| 摘要 |
PURPOSE:To obtain a coil spring which has improved remarkably fatigue strength as compared with a conventional method, by executing uniformly substantially stress shot peening to the outside and the inside of a coil, in a spring material wound in a shape of a coil. CONSTITUTION:Each end part of a coil spring 1 is held by a pair of pedestals 21, 22 of a transfer body 3, respectively, and in this state, the transfer body 3 is constituted so that a coupling hole 11 of its bottom part 33 is engaged with a detaining pin 10 of a carrying conveyor 8. When the transfer body 3 passes through the lower part of a high-speed shot projecting machine 12, the spring 1 is always in a curved state, and also it rotates and passes through a projecting machine 13. Accordingly, the spring 1 itself is subjected to stress shot peening in a state similar to a motion of the coil spring installed to a hanging device of an automobile. Also, it can receive an uniform stress shot peening action not only in the inside and the outside of the spring 1, but also over the whole periphery of a coil strand.
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