| 摘要 |
PURPOSE:To prevent the thickness of a cavity part from decreasing by working the cavity part in the center part of a semispherical forming base material in a state that its outside circumferential edge part is not detained, and subsequently, forming a flange part in a state that the outside circumferential edge of the base material is bend and drawn. CONSTITUTION:A blank material W formed semispherically in advance is placed on the second blank holder 8, a punch 2 is moved downward, and a cavity part Wa is bend and drawn in the center by the first die 5 and the first punch 3. In this case, since the outside circumferential edge of the blank material W is not detained, it scarcely occurs that the blank material W is drawn into the center part side and the thickness of the cavity part Wa decreases. Subsequently, the punch 2 moves downward, the second die 6 is supported by the second punch 4, and the outside circumferential edge of the blank material W is bent and drawn. Subsequently, press work of a flange part Wb of the blank material W is executed by the first die 5. In this case, the thickness of this part is controlled with respect to its fluidity to the outside circumferential edge side since the outside circumferential edge is detained in a bent and drawn state, flows to the cavity part Wa side of the center, and a thickness increasing effect of the cavity part Wa is obtained. |
