PISTON FOR INTERNAL COMBUSTION ENGINE AND METHOD FOR MANUFACTURING SAME

摘要

Valve recesses (26, 28, 30, 32) are formed in the upper surface of a crown part (14). A flat outer circumferential part (36) having the same height as the outer edge (14a) of the crown part (14) is formed between the valve recesses (28, 30). A punch mark (A) is applied to the outer circumferential part (36). A tapered part (50) is formed on the outside of a cavity (42). An anodic oxide film (52) is formed on the cavity (42) and the tapered part (50) so as to be on the inside of the inner edges (26a, 28a, 30a, 32a) of the valve recesses (26, 28, 30, 32).