| 摘要 |
PROBLEM TO BE SOLVED: To provide a cold forging type manufacturing method of a butterfly screw having favorable strength, hardly causing fracture of both blade parts, and hardly causing corrosion. SOLUTION: In a first process, a circular wire rod material is fed into a rolling machine, and the rolling machine rolls the circular wire rod material into a circular wing material having both blades. In a second process, the wing material is cut to individual wing materials one by one by a cutting die and scissors. In a third process, both cut surfaces of the invididual wing material is retouched smooth to hold the circular part of the central part and oblong blades on both sides. In a fourth process, a recess is formed on both side surfaces of the central part of the individual wing material by pressing. In a fifth process, the bottom of the recess of the individual wing material is removed to form a through hole. In a sixth process, the blade parts on both sides of the individual wing material is bent upward and shaped like a butterfly to form the individual butterfly material. In a seventh process, a female screw is threaded in the through hole of the individual butterfly material. Thus, a butterfly screw is manufactured. COPYRIGHT: (C)2006,JPO&NCIPI
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