Punch for forming screw heads has wings on side surfaces of punch head to leave notches in surface of screw head to reduce stress

摘要

The die (2) consists of a punch (21) with a recess (22) in its endface which is the negative of the screw head to be formed. A punch head (23) projects from the middle of this recess. There are wings (24) on the side surfaces of the punch head, of such a size that they leave notches in the surface of the screw head to relieve points of excess mechanical stress.