| 摘要 |
PURPOSE:To prevent thinning of a recessed part, by a method wherein material is kept formed on the recessed part of the tip of a punch as an allowance material and the same is moved to an uneven-patterned part at the bottom dead point of the punch, in draw molding based on a confronting liquid pressure molding method. CONSTITUTION:Draw molding is performed by confronting liquid pressure Pc by making the punch 4 descend after a recessed part 4d has been formed on the tip part of a punch 4 and a material 6 has been pressed by a presser foot 1 of creases. As for the material 6, an allowance part 6d is formed on the recessed part 4d by the liquid pressure Pc. The liquid pressure is made to reduce at a point directly before the bottom dead point and movement of the allowance part 6d to parts 6b, 6c is made possible. When the punch is made to descend further, a recessed part 3a of a die acts upon the material so as to press the material into a recessed part 4b of the punch and a necessary material for that is replenished by a method wherein the allowance part 6d formed in the recessed part 4b is deformed into the plane. Partial extension and reduction of thickness in an uneven part are little. |
