| 摘要 |
A method of manufacturing a ring-shaped member in which the outer sides of the pair of curved parts (3d) of a longitudinal annular blank are pressingly energized by the molding outer dies (14) of a pressing device (13) in the directions of the opposite side curved parts (3d) to push open each of the curved parts (3d) to a large curved part with a large radius of curvature to mold a half-finished product (17), and the half-finished product (17) is pushed open by a cooperation between the finishing inner die of the pressing device and a complete round type window part functioning as the outer die to manufacture the ring-shaped member. Since a yielding indicated by the ratio of the weight of the ring-shaped member to the weight of a raw material and a yielding indicated by the ratio of the ring-shaped member to the blank are increased, a manufacturing cost for the ring-shaped member can be reduced.
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