Patent ID: 7581941

Claim:
A punch comprising: a center punch and an outer punch surrounding the outer periphery of the center punch, both of the center punch and the outer punch being slidable and capable of compressing operation; and relative position restriction means for restricting a relative position of the center punch and the outer punch, the relative position restriction means being configured to restrict a first position in which the punch tip of the center punch is protruded from the punch tip of the outer punch and a second position in which the punch tip of the center punch is substantially coincident with the punch tip of the outer punch, and being configured to fail to restrict a third position in which the punch tip of the center punch is retracted in the punch tip of the outer punch, wherein the relative position restriction means comprises a first restricting component provided on the center punch and a second restricting component provided on the outer punch; both of the first restricting component and the second restricting component are shaped annular and comprising a projected-depressed portion having a projected portion and a depressed portion; the first restricting component and the second restricting component are positioned with their respective projected-depressed portion facing each other: at least one of the first restricting component and the second restricting component is rotatable on a punch axis of the center punch; and as a result of its rotation, the projected portion of one of the restricting components and the depressed portion of the other restricting component are positioned to be allowed to come close to each other or the projected portions of both restricting components are positioned to be allowed to come into contact with each other.