| 摘要 |
PURPOSE:To enable the execution with good accuracy of the punching of a hole by the double lapping of a metallic sheet by providing the annular projection of a right-angled triangular sectional shape having vertical outer periphery and an inclination on the inner periphery around the hole of a female die. CONSTITUTION:It is formed by the upper die A providing a male die 1, the holder 5 to support therefor, plate presser 2 and the elastic body for generating the plate pressing force P2 and by the lower die B consisting of the female die 3 providing annular projection 4, etc. The cross section of the annular projection 4 having a vertical outer periphery and an inclination on the inner periphery is made a right-angled triangular shape on the slightly outer diameter side than the edge of the hole H of the female die 3. The generation of deformation can be prevented since the plastic fluidity in the outer peripheral direction to be caused around the hole is stopped by the annular projection 4 when the metallic plates 7, 8 are subjected to a hole making by applying a drawing force P1 with the male die 1. The double drawing is thus performed.
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