Patent ID: 7628050

Claim:
A press-working method comprising: cutting out a member with a predetermined shape from a sheet material, the member having a longitudinal direction; forming a cut-out portion for forming an opening in the interior region of the member, while allowing a blank part to remain inside the cut-out portion, wherein the cut-out portion corresponds to an outer contour of the opening; bending the member with the predetermined shape to form a bottom portion and a wall portion extending at an angle from the bottom portion as seen in a direction along the longitudinal direction such that the bottom portion has an arched surface as seen in a side view, using at least one plunger and at least one die, the step of bending comprising deforming the outer contour of the opening; and removing the blank part from the cut-out portion to form the opening, wherein an edge of the wall portion is allowed to expand along the plunger and the die while changes in a thickness of the wall portion is controlled by the plunger and the die, wherein the step of cutting out a member is performed such that the wall portion has an edge with a preset shape after the bending step, and wherein the step of bending further includes: a first bending step for bending the member to form the bottom portion and the wall portion with a first plunger and a first die; and a second bending step for bending the bottom portion by a second plunger and a second die into having the arched surface while controlling the change in the thickness of the wall portion with the second plunger and the second die and while allowing the edge of the wall portion to expand along the second plunger and the second die.