| 摘要 |
An inner punch (11), an outer punch (12), and a die (13) are disposed on the same center axis (10). The outer punch (12) is disposed so as to be apart from the inner punch (11) in a radial direction perpendicular to the center axis (10) by a first space S1 which is larger than a plate thickness T of a cup longitudinal wall portion (A2). Further, an inner peripheral surface of the outer punch (12) has, on its die (13) side, a punch shoulder R portion (12A) widening as it goes toward the die (13). A cup bottom portion (A15) is sandwiched by the inner punch (11) and the die (13) while an outer peripheral surface of the inner punch (11) and an inner peripheral surface of the cup longitudinal wall portion (A2) are apart from each other by a second space S2, and drawing to radially reduce the cup longitudinal wall portion (A2) is performed by pushing the cup longitudinal wall portion (A2) toward the outer peripheral surface of the inner punch (11) by the outer punch (12) while making the outer punch (12) abut on the cup longitudinal wall portion (A2) from the punch shoulder portion (12A), whereby a surplus material is made to flow into a cup shoulder portion (A1) to thicken the cup shoulder portion (A1). |
