| 摘要 |
PROBLEM TO BE SOLVED: To obtain a product which is scarcely oxidized nor corroded intergranularily by increasing a density at grain boundary as well as decreasing the number of grain boundaries appearing on the surface of the product. SOLUTION: An annular die (7) having a forming surface (7a) on one of an inner peripheral surface or an outer peripheral surface is provided, and the other of the peripheral surfaces of the die (7) is taper-fitted (8) in a die guide (5). An intermediate product (15) formed on a surface to be formed (15a) and having a prescribed ironing allowance (T) against the casting surface (7a) is provided. An ironing punch (10) to force the intermediate product (15) into the die (7) and a die punch (11) which relatively displaces at least one of the die (7) and the die guide (5) at the operational end of the ironing punch (10) against the other in the axial direction for elastically deforming the die (7) in the radial direction through the taper-fitted (8) portion are provided. COPYRIGHT: (C)2004,JPO
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