| 摘要 |
PURPOSE:To improve a forming accuracy by applying a pressure on the outer peripheral face of a die via a pressure medium and constraining the opening and deformation of a die as well. CONSTITUTION:The material 5 to be worked is arranged at the inner side of a split die 1 and the outer cylinder 2 having larger inner diameter than the outer diameter of the die 1 is arranged by supporting it with a die supporting cylinder 6. In this case, the outer cylinder 2 and the end face of the die 1 are pressed with the load Fo of an end face plate via the rail material of an O ring 7, packing 8, etc. An inner pressure Pi is applied on the material 5 to be worked in the state of applying a pressure Po on the die outer peripheral face and a pressure rod 4 is pressed with a load Fi via an O ring 11 to perform a bulge forming. The inner pressure Pi acting on the die 1 and the stress based on the external pressure Po are superimposed and reduced, so the deformation and opening of the die are reduced. Consequently the forming accuracy of a product is improved.
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