| 摘要 |
PURPOSE:To forge a half-assembled crank throw in good yield. CONSTITUTION:In a forging method integrally forging an arm part and a pin part in the half-assembled crank throw in a die device, a roughly forging blank 13 having polygonal columnar shape is charged into an arm part forming surface 11A in the die device 10 provided with the die 11 having the reverse conical shaped arm part forming surface 11A and an anvil 12 for forming the pin part at the reverse conical bottom, and centering is executed. Thereafter, by pressing triangular conical punch 14 into the roughly forged blank 13, the blank is forged into the arm part 15A and the pin part 15B with the arm part forming surface 11A and the anvil 12 for forming the pin part, respectively. Thereafter, the blank 13 is taken out from the die device 10 and the arm part 15A is extensively forged.
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