PURPOSE: To enable cutting in a short time through plastic working by pressing of a thick plate material in cutting a thick plate material such as a flange part of a plate spoke wheel by using a general purpose press having specified structure.

CONSTITUTION: In a general purpose press, an upper tool 18 and a lower tool 14 having tip edges 18a, 14a are attached to an upper die and a lower die respectively to constitute a plastic working die for cutting. Further, an upper die 17 and a lower die 13 are held in vertical direction allowing sliding and the upper die 17 is enabled to make vertical relative movement in relation to the upper tool 18 by a hydraulic cylinder incorporated in the upper die. At the same time, a spring 37 of the lower die 13 is enabled to make vertical relative movement in relation to the lower tool 14 by air pressure. In cutting by plastic working, after working a V-groove for cutting outline by edges 18a, 14a of the upper and lower tools, the upper die 17 is pressed downward by the cylinder 20, and the thick plate is cut along the V-groove.