Press forming method

摘要

A press forming apparatus (1a) consecutively carries out: a first step of pushing a flat plate-shaped workpiece into a die (14) by a forming punch (11), to form the workpiece into a cup-shaped workpiece (B); a second step of making the cup-shaped workpiece (B) move relatively to a position where a space (S2) is formed between a cup bottom part (B2) and the forming punch (11) by a holding down member (12) abutting on an end part of a cup vertical wall part (B1); and a third step of making a counter punch (13) approach the forming punch (11), to push a cup bottom part (B2) to a forming punch (11) side so that the cup bottom part (B2) is compressed by the forming punch (11) and the counter punch (13), making a material of the cup vertical wall part (B1) flow to a cup shoulder part (B3), thereby to thicken the cup shoulder part (B3).

主权项

1. A press forming method carrying out press forming to a flat plate-shaped workpiece by using a press forming die which has a forming punch, a holding down member disposed along an outer periphery of the forming punch, a counter punch disposed to face the forming punch in a center axis direction, and a die in whose insertion hole part the counter punch is disposed and one end side inner wall surface of whose insertion hole part into which the forming punch is inserted is a die shoulder part, center axes thereof being coaxially disposed to one another, the press forming method sequentially comprising:
a first step of pushing the flat plate-shaped workpiece into the insertion hole part via the die shoulder part by making the forming punch move relatively in relation to the die and be inserted into the insertion hole part, thereby to form the workpiece into a cup-shaped workpiece having a cup vertical wall part, a cup bottom part, and a cup shoulder part connecting the cup vertical wall part and the cup bottom part; a second step of making the cup-shaped workpiece move relatively in relation to the forming punch, to a position where a space is formed between the cup bottom part and the forming punch by the holding down member abutting on a cup opening part side end part of the cup vertical wall part; and a third step of restraining deformation in a plate thickness direction of the cup vertical wall part by the forming punch and the die and making the counter punch approach the forming punch in a state where a relative position in relation to the forming punch of the cup vertical wall part is fixed by the holding down member, to push the cup bottom part to a forming punch side, to make the cup bottom part compressed by the forming punch and the counter punch, and to make a material of the cup vertical wall part flow to the cup shoulder part, thereby to thicken the cup shoulder part.