| 摘要 |
PURPOSE:To prevent ear formation and to improve product yield by restricting a flow of a material into a hole of a die by expanding hydraulic chambers upward, by providing a set of die constituting of a die, blank holders and a punch, and providing the hydraulic chambers to one side of the blank holder. CONSTITUTION:A disk-shaped metallic thin plate 16 is set on the upper surface of a die 1 so as to locate the root of the lug of the plate 16 on respective hydraulic chambers 81-84. Next, a blank holder 2 is descended by driving cylinders 121 and 122 to press the plate 16 against the upper surface of the die 1 by a prescribed force. On the other hand, the die surface being the upper surface of the hydraulic chambers is expanded upward by an elastic deformation to apply a larger force to the root of the lug by supplying a pressurized oil to the chambers 81-84. Next, a punch 3 is descended by driving a cylinder 13 to force the plate 16 into a die hole 7, and forms a cylindrical vessel while dragging down the surrounding material. |
