PISTON FOR AUTOMATIC TRANSMISSION AND MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a piston easy to be incorporated into a counter-piston, having high axial-center direction dimensional accuracy without requiring special working for the counter-piston and preventing the generation of a burr at a rubber coating process. SOLUTION: This piston is provided with a piston body 2 having a peripheral wall 7 parallel to a piston axial center. The tip surface part 11 of the peripheral wall 7 has a round part R and a flat surface part F. The round part R is formed by press bending. The flat surface part F is formed by press pressure crushing.