Patent ID: 7473182
Filing Date: 2009-01-06
Classification: B21K,B23P,F16B,Y10S

Abstract:
1. A method of manufacturing a fastener said fastener having a shank and a head, said method comprising: constructing a cylindrical steel blank having a predetermined length; drilling an axial bore from a top to a bottom of said blank; inserting a wire through said bore for providing an EDM operation and machining said recess using said wire EDM operation to form a die cavity, wherein said die cavity is constructed having a central portion and a plurality of wings radiating outwardly from the central portion, each of the wings having an installation wall and a removal wall, and further wherein, in said machining operation, transition surfaces are constructed extending between each of the installation and removal walls of adjacent wings, at the radially inner most extent of said wings, each of said transition surfaces formed having an interference contour extending radially inward into the central portion, said contour being tapered from a first radial distance from the longitudinal axis at a top portion thereof to a second radial distance from said longitudinal axis at a bottom portion thereof; and wherein said first radial distance is larger than said second radial distance hardening said blank to form a hob and forming a punch using said hob; and forming a recess on the head of the fastener by using said punch.