| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of an internal combustion engine piston, improving productivity, moldability and yield of an undercut portion, and reducing the number of machining processes. SOLUTION: When forging a skirt part 6 in the manufacturing method for the piston which divides and forges a crown part and the skirt part 6 respectively, and bonds and integrates by means of friction-welding the crown part with skirt part 6, a recessed part 9 is provided on both sides of inner peripheral surfaces of a female mold 1 corresponding to a circumference of a pin boss part of the skirt part 6. A material of the skirt 9 is cast into the female mold 1, and pressed and forged by a male mold 2, with mounting a core piece 3 for molding a circumference of the pin boss part to a substantially flat recessed surface around the recessed part 9. |
