| 摘要 |
PROBLEM TO BE SOLVED: To ensure the required amounts of both the offset of a pin part and the extension of an arm part from a journal part of a crankshaft to be manufactured. SOLUTION: A manufacturing apparatus 1 for manufacturing a crankshaft out of a shaft material 5 by the cold forging includes a lower die 3, an upper die 4 and a first cylinder 11 or the like for compressing the shaft material 5 in the axial direction, an intermediate die 6 and a second cylinder 14 or the like for pressing an intermediate portion 5a of the shaft material 5 in the specified direction SD in the radial direction independently from the upper die 4 and the first cylinder 11 or the like, and a controller 22 for controlling the pressure caused by the intermediate die 6 and the second cylinder 14 or the like. The controller 22 controls the start timing of the pressure in the specified direction SD by the intermediate die 6 and the second cylinder 14 or the like to the predetermined value of≤0.15 in terms of the "compression advancing ratio" according to the advancement of the compression in the axial direction caused by the upper die 4 and the first cylinder 11 or the like. COPYRIGHT: (C)2011,JPO&INPIT
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