Patent ID: 7112142

Claim:
A method of cold forming a self-attaching female fastener element, comprising the following steps: cold forming a female fastener element blank including an annular projecting central pilot portion having an end face, a bore through said pilot portion through said end face, an annular flange portion surrounding said pilot portion having an end face spaced below said end face of said pilot portion, an annular groove in said end face of said flange portion having a bottom wall and generally parallel side walls including an inner side wall adjacent said pilot portion extending generally perpendicular to said end face of said pilot portion and an outer side wall extending generally perpendicular to said end face of said flange portion, a first annular protrusion extending from said end face of said pilot portion adjacent said inner side wall of said annular groove and a second annular protrusion extending from said end face of said flange portion adjacent said outer side wall of said annular groove; deforming said first annular protrusion radially outwardly to overly said bottom wall of said groove; and substantially simultaneously deforming said second annular protrusion radially inwardly to overlie said bottom wall of said groove forming a generally planar end of said flange portion, thereby forming an annular re-entrant groove having a radial opening at said end face of said flange portion having a width less than a radial width of said bottom wall of said groove.