| 摘要 |
PURPOSE:To obtain an equipment at low cost, to obviate noise, and to easily execute a mass production by inserting and holding a coil springshaped object which has been constituted to a winding diameter of prescribed times or more of a wire rod diameter, between two opposed surfaces, and narrowing it. CONSTITUTION:A coil spring 8 which has been manufactured to a winding diameter of >= three times of a wire rod diameter is inserted into between upper and lower pressure dies 6, 7 rolled between two surfaces of these dies, and an interval between these two surfaces is narrowed gently. By reducing gradually the winding diameter of the coil spring 8, a coil spring having a winding diameter of < three times is manufactured.
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