STUDIES ON DOUBLE-SIDE SHEARING WITH PARALLEL AND STRAIGHT CUTTING EDGES (PREVENTION OF TOOL BREAKAGE BY BEVELED PUNCHES WITH HIGH SLENDERNESS RATIO)

In the present investigation the cutting edge of a slender punch was b evelled in an attempt to prevent bending or breakage in use. Tests wit h Kovar sheet showed that use of a bevelled punch significantly reduce s the risk of bending or breakage, a particular problem when clearance on both sides of the punch is unbalanced. This is because the punch g uides itself in the later stage of the stroke. Tool life tests shearin g Kovar sheet with the bevelled punch produced a smaller burr on the p roduct than with the conventional punch. The application of such punch es is found to be most suitable for thin materials such as are used in the manufacture of IC and LSI parts.