| 摘要 |
PROBLEM TO BE SOLVED: To provide a forged piston for internal combustion engine and its manufacturing method which can make an aluminum alloy flow in to a thin wall part sufficiently without increasing the forging load, can transmit the heat in a combustion chamber to a cylinder wall sufficiently, and can prevent the problem of an engine overheating. SOLUTION: In the forged piston 1 for internal combustion engine provided with an about disk form head 2, a pair of pin bosses 4 and 4 extended downward from two position parts on a piston pin axial line at the lower side of the head 2, skirt parts 3 and 3 extended downward from at least both side parts of the above piston pin axial line at the outer peripheral edge of the head 2; and plural ribs 5 extended downward from the lower side of the head 2, and to connect the pin bosses 4, the skirt parts 3, and the head 2, the skirt parts 3 are set in an inclined thick wall member which is made the thicker, as the closer to the head 2 side, while the plural ribs 5 are set in an even thick member whose thickness in the axial direction is even.
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