| 摘要 |
A method of manufacturing a ring-shaped member capable of reducing cost by increasing a yield represented by the ratio of the weight of the ring-shaped member to the weight of a raw material and a yield represented by the ratio of the weight of the ring-shaped member to the weight of a blank. A half-finished product (18) having largely curved parts (3D) formed by enlarging curved parts (3d) to increase its radius of curvature more than its initial radius of curvature and expansion parts (3E) curvedly formed in a circular arc shape on linear parts (3b, 3c) with a radius of curvature larger than the radius of curvature of the curved parts (3d) is molded, and then the half-finished product (18) is molded in a ring shape to provide the ring-shaped member (1).
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