Method of making steel rule type piercing and blanking dies

摘要

A steel rule first die is made by mounting steel rule elements, and other shearing elements if desired, in a die block in known manner. A punch die blank is mounted on a support having means for aligning the blank with such shearing elements. One or more layers of adhesive tape of predetermined thickness are applied to the shearing side face of the shearing elements to define a clearance-producing layer thereon. Foamed plastic blocks are adhered to the punch blank so as to form defined areas on its face opposite the shearing elements of the first die, and an adherent impressionable soft layer of hardenable resin is applied to such defined areas. The first die is then assembled in aligned relation with the punch die blank, with its shearing elements impressed deeply in the soft resin layer so as to form wide edge faces in such layer against the clearance-producing layer of tape on the shearing side faces of the shearing elements. The resin layer is hardened and the punch blank is then removed from the assembly with the die element impression fixed thereon. The edge faces are desirably coated with a contrasting color which may penetrate the hardened resin. The punch blank is then machined to the hardened impression, and the machining step is controlled in accordance with removal of color from the edge faces which define the die element impression. This forms a punch which accurately matches the shearing elements of the first die, with clearance therefrom corresponding to the thickness of the tape. The tape and resin are removed, and the steel rule die and the punch are mounted in a die set for use.