| 摘要 |
A hollow spring and a production method therefor, which can improve the durability and the efficiency of inner surface abrasive blasting for spring material, are provided. A straight-shaped hollow spring material W is used in a blasting apparatus 100. The length of the spring material W is set to be 1.5 m to 3.5 m, and the inner diameter of the spring material W is set to be not more than 10 mmÕ (not including 0). In inner surface abrasive blasting for the spring material W, first blasting and second blasting are performed in turn. In the first blasting, abrasives are ejected to an opening portion Wa of the spring material W and are suctioned from an opening portion Wb thereof. In the second blasting, the abrasives are ejected to the opening portion Wb of the spring material W and are suctioned from the opening portion Wa thereof. Thus, the inner surface of the spring material W can be prevented from having a trumpet shape. The ejection pressure, the suction pressure, and the like are appropriately set, so that generation of grinding amount difference between the center portion and both end portions of the inner surface of the spring material W can be inhibited. |
