| 摘要 |
PURPOSE:To perform the processing so as to obtain a uniform quality, by contacting a coil spring with the surface of a drum, holding both ends thereof by rotary wheels at a specified interval, and thereafter hitting shot particles together with compressed air with the spring being rotated. CONSTITUTION:At fist, a coil spring is mounted on holding bodies 13 and 13, which are fixed to rotary wheels 12 and 12 of a processing device 10, and the rotary wheels 12 and 12 are rotated at a specified speed. Then, the coil spring begins the rotation under the state the spring is contacted with the outer surface of the drum 11. Then, the coil spring revolves around the drum 11 following the rotary wheels 12 and 12. Under this state, minute steel balls are made to hit the coil spring together with compressed air through a jetting hole 16 from a jetting gun 15, which is located in the vicinity of the coil spring. At this time, since the jetting hole 16 has a shape of long and thin hole, which is extended in one direction, the steel balls are made to flow along the entire length of the coil spring and to hit the spring uniformly, the surface layer is hardened, residual stress by the compression is increased, and the fatigue strength is improved. |
