Patent ID: 9707617
Date: 2017-07-18
CPC Classifications: B21D,B21J,B21K

Claim:
1. A press-forming method using a press mold which includes an inner punch, an intermediate punch disposed along an outer periphery of the inner punch, an outer punch disposed along an outer periphery of the intermediate punch, an inner die, an intermediate die disposed along an outer periphery of the inner die, and an outer die disposed along an outer periphery of the intermediate die, a central axis of each of which is disposed coaxially, and in which the inner punch, the intermediate punch, and the outer punch are disposed to face the inner die, the intermediate die, and the outer die, respectively, the method comprising: while compressing a first compression part in a bottom wall part of a workpiece formed into a cup shape by the inner punch and the inner die and moving the first compression part in a direction away from the intermediate die, pushing the inner die toward the inner punch; and compressing a second compression part being an outer end portion in a radial direction of the workpiece by the outer punch and the outer die and moving the second compression part in a direction to approach the intermediate die, to thereby suppress the workpiece in the second compression part from material-flowing in a direction away from the central axis, whereby thickness reduction processing of the first compression part and thickness increase processing of a vertical wall part of the workpiece sandwiched by the intermediate punch and the inner die and a vertical wall part of the workpiece sandwiched by the intermediate punch and the outer die are performed.