Self-piercing clinch nut

A self-clinching fastener for attachment to a plastically deformable metal panel, said self-clinching fastener comprising a body portion with a central axis and a central pilot portion extending from said body portion and coaxial with said central axis, said body portion forming a generally annular-shaped end face adjacent said central pilot portion and a groove defined in said end face encircling said central pilot portion, said groove having an inner wall formed by a plurality of generally flat faces and a bottom wall formed by a plurality of generally flat faces, said faces of said bottom wall being aligned with said faces of said inner wall, and a plurality of spaced apart lugs encircling said central pilot portion and axially extending from at least one of said end face and said groove, said lugs forming abutments to improve torsional resistance of said fastener.

A method of attaching a self-clinching fastener to a plastically deformable metal panel, said method comprising the steps of:

• (a) coaxially positioning the fastener and a die member on opposite sides of the metal panel at a position in which the fastener is to be secured to the metal panel;
• (b) orienting the fastener and the die member so that a plurality of inclined faces in a groove of the fastener and a cooperating plurality of inclined faces of the die member are circumferentially aligned;
• (c) relatively moving the die member and the fastener toward one another in an axial direction to deform a portion of the panel into the groove of the fastener by coining the panel between the inclined faces of the fastener and the inclined faces of the die member and on opposite sides of lugs configured to improve torsional resistance of the fastener until a secure mechanical interlock is formed between the fastener and the panel.

A self-clinching fastener for attachment to a plastically deformable metal panel, said self-clinching fastener comprising a body portion with a central axis and a central pilot portion extending from said body portion and coaxial with said central axis, said body portion forming a generally annular-shaped end face adjacent said central pilot portion and a groove defined in said end face encircling said central pilot portion, said groove having an inclined inner wall forming an undercut and an inwardly inclined bottom wall such that said groove has an increasing depth in a direction toward said undercut, said inclined bottom wall being inclined at an angle greater than 2 degrees and less than about 50 degrees relative to a plane perpendicular to the central axis, and a plurality of spaced apart lugs encircling said central pilot portion and axially extending from at least one of said end face and said groove, said lugs forming abutments to improve torsional resistance of said fastener.