Method of punching template for forming a base plate of a tape cassette

摘要

A method for punching a template is provided comprising the steps of partially punching the template by applying a first punch to a first surface of the template to form a recessed portion thereof and by applying a first die to a second surface of the template to form a projected portion thereof, so as to produce a first shear plane connected with the first surface on a peripheral surface of the recessed portion and a second shear plane connected with the second surface on a peripheral surface of said projected portion; returning the projected portion so as to be substantially aligned with the recessed portion by holding the first surface and the second surface between a second punch and a second die; and fully punching the template by applying a third punch to the second surface and a third die to the first surface to as to produce a third shear plane connected with the second surface on a peripheral surface of the recessed portion and a fracture plane connected between the third shear plane and the first shear plane thereby causing a portion of the template to fully punched therefrom.