Patent ID: 9511403
Filing Date: 2016-12-06
CPC Classification: B21D

Claim Text:
1. A press forming method comprising press forming a workpiece between a die and a first punch, while pushing the first punch into the die by means of a relative motion of the die and the first punch, producing an intermediate molding having vertical walls, a ceiling, and a ridge formed in an angular part between the vertical walls and the ceiling of the workpiece and having an intermediate shape with a section line length which is 2% to 10% larger than the section line length of a final shape, holding the intermediate molding between a pad and a second punch, and stamping the ridge in the intermediate molding at least once so as to shape the intermediate molding into the final shape, thereby substantially thickening and work hardening the angular part between the vertical walls and the ceiling of the workpiece, wherein the ratio of widths of the pad and the second punch is 0.4 to 0.8.