| 摘要 |
PROBLEM TO BE SOLVED: To prolong the service life of a die by press-fitting a metallic material in a groove part formed in the die to form a pin boss part and a rib part to avoid generation of cracks when a stock of a structure in which the pin boss part and a skirt part are connected by the rib part suspended from a back side of a head part is forged with the die out of a piston stock of a metallic ingot. SOLUTION: In a manufacturing method of a forged piston in which a stock of a metallic ingot is forged into a forged stock in which a pin boss part and a skirt part are connected by a rib part suspended from a back side of a head part, and machine-finished to manufacture a product, when a formed stock 11 of approximate piston shape is formed out of a stock 10 of a metallic ingot through the forging by the die, die members 22 (22a, 22b) to form the pin boss part, the skirt part, and the rib part, are split by a splitting plane 24 passing through each lower end of the pin boss part, the skirt part and the rib part.
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