to the degree of curvatures of the punched products the graph compares the case of using the shape punched plate and that of not using it as shown in fig9 the punched products have curvatures at the beginning of the operation according to the invention however these degrees of curvatures are very low in comparison with the case of not using the shaped punched plate in the invention the curvature is greatly reduced when 50 to 100 punchings are performed that is in the case of the ultra plastic die without the shaped punched plate the depth of the curvature after 1000 times is about 1 3 mm and in the invention it is possible to reduce about 1 6 thereof the curvature of the product is caused by the fact that size of the female portion is most enlarged at the cutting corner of the die body owing to abrasion and the punched part having a diameter which is urged within the female portion on the other hand the invention cutting edge is composed of the hard thin plates 4a 4b and the abrasion is as shown in fig1 generated in the side wall of the female portion of the soft die body 2 therefore the curvature is formed at the beginning due to the abrasion in the side wall but after an abrasion is formed in some degree an appropriate relief 32 is formed thereby and thus the curvature of the product is extinguished v the inventors made use of the zero clearance of the punching die of the roundness.