| 摘要 |
PROBLEM TO BE SOLVED: To provide a forging method for forming a hollow parts having a deep hole and a branched part formed in a side thereof without defects. SOLUTION: A manufacturing method of a metal parts having a branched part on an outer periphery of the hollow parts having the deep hole comprises a step of inserting a stock 7 in a die, a step of forming a deep hole in the stock by first punch 3 and a counter punch 5 disposed at the position facing the first punch 3, a step of moving the stock to the position passing the space for forming the branched part without changing the relative position of the first punch 3 to the counter punch 5 in the above step, and a step of expanding the stock sidewise by the first punch 3 and the counter punch 5, and a hollow part is formed in the branched part by a second punch 4 successive to the step of expanding the stock sidewise.
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