Patent ID: 9328824
Filing Date: 2016-05-03
CPC Classification: B21D,B21K,F16J,Y10T

Claim Text:
1. A manufacturing method of a cylinder member of an automatic transmission, wherein the cylinder member includes an annular bottom face portion, a cylindrical inner peripheral wall portion projecting upright from an inner peripheral edge of the bottom face portion, and a cylindrical outer peripheral wall portion projecting upright from an outer peripheral edge of the bottom face portion, the inner peripheral wall portion has an inner peripheral constant portion having a constant outer diameter, and has an inner peripheral introducing portion on a distal end of the inner peripheral wall portion, the inner peripheral introducing portion having an outer diameter smaller than the outer diameter of the inner peripheral constant portion, the outer peripheral wall portion has an outer peripheral constant portion having a constant inner diameter, and has an outer peripheral introducing portion on a distal end of the outer peripheral wall portion, the outer peripheral introducing portion having an inner diameter larger than the inner diameter of the outer peripheral constant portion, the outer peripheral constant portion has a through hole that communicates between an inner peripheral side and an outer peripheral side, and a positioning claw portion is provided at least one position of the outer peripheral introducing portion in a circumferential direction and projects to the outer peripheral side, the manufacturing method comprising: a drawing step in which a cylindrical preliminary outer peripheral wall portion is formed by projecting upright an outer peripheral side of an annular material; an outer peripheral wall portion ironing step in which ironing is carried out for forming the preliminary outer peripheral wall portion into the outer peripheral wall portion by an outer peripheral wall portion forming punch and an outer peripheral wall forming die, the outer peripheral wall portion forming punch having an outer peripheral wall portion forming surface provided on an outer peripheral surface of the outer peripheral wall portion forming punch and corresponding to an inner peripheral shape of the outer peripheral wall portion, and the outer peripheral wall forming die having an ironing hole corresponding an outer peripheral shape of the outer peripheral wall portion; an inner peripheral wall portion forming step in which the inner peripheral wall portion is formed by an inner peripheral wall portion forming punch and an inner peripheral wall portion forming die, the inner peripheral wall portion forming punch having an inner peripheral wall portion forming surface provided on an outer peripheral surface of the inner peripheral wall portion forming punch and corresponding to an inner peripheral shape of the inner peripheral wall portion, and the inner peripheral wall portion forming die having an inner peripheral wall portion forming hole corresponding to an outer peripheral shape of the inner peripheral wall portion; a punching step in which the through hole is formed by a piercing punch arranged at a position corresponding to the through hole, and a piercing die having a punched hole corresponding to the piercing punch; and a claw forming step in which the positioning claw portion is formed by a claw forming punch arranged at a position corresponding to the positioning claw portion on an inner peripheral side of the outer peripheral wall portion, and a claw forming die having a recessed portion corresponding to the claw forming punch, wherein, in the outer peripheral wall portion ironing step, the outer peripheral introducing portion is formed, the outer peripheral introducing portion including an diameter-increased straight portion having a constant inner diameter that is larger than the inner diameter of the outer peripheral constant portion, and an diameter changing portion which smoothly connects the diameter-increased straight portion and the outer peripheral constant portion.