Abstract: A self-clinching fastener for attachment to a plastically deformable metal panel includes a body portion with a central axis and a central pilot portion extending from the body portion and coaxial with the central axis. The body portion forms a generally annular-shaped end face adjacent the central pilot portion and a groove defined in the end face encircling the central pilot portion. The groove has an inclined inner wall forming an undercut and an inwardly inclined bottom wall such that the groove has an increasing depth in a direction toward the undercut. The inclined bottom wall is formed by a plurality of generally flat faces and the inclined inner wall is formed by a plurality of generally flat faces which are aligned with the faces of the bottom wall. The fastener further includes a plurality of spaced apart lugs encircling the central. pilot portion and axially extending from at least one of the end face and the groove. The lugs form abutments to improve torsional resistance of the fastener.

Abstract: A self-clinching fastener for attachment to a plastically deformable metal panel includes a body portion with a central axis and a central pilot portion extending from the body portion and coaxial with the central axis. The body portion forms a generally annular-shaped end face adjacent the central pilot portion and a groove defined in the end face encircling the central pilot portion. The groove has an inclined inner wall forming an undercut and an inwardly inclined bottom wall such that the groove has an increasing depth in a direction toward the undercut. The inclined bottom wall is formed by a plurality of generally flat faces and the inclined inner wall is formed by a plurality of generally flat faces which are aligned with the faces of the bottom wall. The fastener further includes a plurality of spaced apart lugs encircling the central pilot portion and axially extending from at least one of the end face and the groove. The lugs form abutments to improve torsional resistance of the fastener.

Abstract: A washer for a male or female threaded fastener includes an annular ring portion and a seat portion with a cantilever portion extending therebetween. The washer hardness is selected to exceed the threaded fastener hardness by an amount that enhances the elastic deflection of the washer and reduces the tendency of the fastener to loosen. The selected hardness relationship also reduces the washer diameter dilation during loading and the permanent deformation of the washer diameter.

Abstract: A fastener assembly with a break mandrel blind rivet and a mating female component having head and tubular shank portions. The tubular shank includes major and minor bore sections and an intermediate internal shoulder. The blind rivet telescopes into the female component to provide a grip range. Positive axial draw-up between the rivet and component upon tensioning of the mandrel is achieved by engagement between and expanded area of the blind rivet and the internal shoulder of the femal component. The head of the female component has a central aperture for receiving the end of the mandrel to increase the grip range of the assembly. A plastic case molded around the head closes off the aperture and affords a weatherproof seal.