Punch, apparatus and method for forming opposing holes in a hollow part, and a part formed therefrom

摘要

A punch, apparatus and method for forming opposing holes in a hollow part, and a part formed therefrom. The punch includes an end portion adapted to pierce an entry hole and bend material around the entry hole to form a retained slug along an inner edge of the entry hole. The punch also includes an enlarging portion adapted to enter the entry hole after the end portion to enlarge the entry hole by bending the slug and additional material towards the interior' of the part. The punch has a length greater than a cross-section of the part such that further advancement of the punch through the part punches an exit hole in the part opposite the entry hole.