| 摘要 |
PROBLEM TO BE SOLVED: To provide a parking gear which can be formed out of a plate material and also the strength of a tooth part and serration part thereof can be sufficiently secured, and to provide a method and a device for forming the same. SOLUTION: A work 11 which comprises an external cylindrical part 13, an internal cylindrical part 14, and a bottom plate part connecting bottom edge parts of the parts 13 and 14 to each other is formed. The space between the part 13 and the part 14 is filled with liquid 23. In such a state, a lid is laid between the part 13 and the part 14 and pressed down in the axial direction. The external cylindrical part 13 of the work 11 is pressed and expanded outward in the radial direction, while being thickened, by the pressing force and hydraulic pressure of the liquid 23 that is compressed and pressed by the pressing. In this way, the part 13 is pressed against an outside transfer die 19, which is arranged outward in the radial direction, to form the tooth part. At the same time, the internal cylindrical part 14 is pressed inward in the radial direction while being thickened and pressed against an inside transfer die 21, which is arranged inward in the radial direction, to form the serration part.
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