Patent ID: 6857962
Filing Date: 2005-02-22
Classification: B21K,F16B

Abstract:
1. A method for forming a blind fastener comprising the steps of: (a) cutting off a generally cylindrical slug of metal from a length of cylindrical metal stock; (b) cold forming the metal slug to size while starting a central recess; (c) deepening the central recess and initial formation of the flange or head of the fastener by further cold forming; (d) cold forming knurling and longitudinal cuts substantially through the side walls of the fastener using a cylindrical punch and a mating die having corners formed with a knurl shaped and sharp inwardly directed points, said knurling and cuts being formed by backward extrusion over said corners of said mating die; said mating die being substantially cylindrical for the greater part of its depth; the diameter of the fastener being initially substantially equal to the diameter of the cylindrical portion of said die, and the engagement with said inwardly directed points being substantially limited to the backward extrusion; (e) completing the fastener flange, or head, bowing out sections of the side walls, and punching out a small central slug of metal to fully open the center of the fastener, all by a cold forming step; wherein the foregoing steps are performed in a single multi-station header type; and removing the completed fastener from said header with the sections remaining somewhat bowed out.