Clinch-type fastener member

A joint comprising:

• first and second workpieces, each said workpiece being formed from a material and having an aperture defined by an inner wall therethrough, at least said aperture of said second workpiece includes an internal thread;
• a fastener member seated within at least said aperture through said first workpiece, said fastener member having a first portion and a second portion which defines a shank portion, said first portion having a protuberance thereon which protrudes outwardly from an underside of said first portion, said shank portion having structure defining a retaining groove thereon proximate to said first portion, said protuberance on said first portion engaging a top surface of said first workpiece and deforming the material of which said first workpiece is formed to cause the material to flow into said retaining groove during rotational engagement of said fastener member in said aperture through said first workpiece;
• and
• means associated with said fastener member for attaching said fastener member to said second workpiece comprising a threaded end portion of the fastener member, said threaded end portion being engaged with said second workpiece to bring said first portion of said fastener member into clamped engagement.

A method of forming a joint comprising the steps of:

• (a) providing first and second workpieces, each said workpiece being formed from a material and having an aperture defined by an inner wall therethrough;
• (b) providing a fastener member having a first portion and a second portion being defined by a shank portion, said first portion having a protuberance thereon which protrudes outwardly from an underside of said first portion, said shank portion having structure defining a retaining groove thereon proximate to said first portion;
• (c) providing means associated with said fastener member for attaching said fastener member to said second workpiece;
• (d) initially engaging said fastener member with said first and second workpieces by using said means associated with said fastener member;
• (e) engaging said protuberance on said first portion with a top surface of said first workpiece;
• and
• (f) applying rotational and compressive forces on said fastener member thereby causing said protuberance to deform the material of which said first workpiece is formed to cause said material to flow into said retaining groove provided on said fastener member to provide a mechanical interlock between said fastener member and said first workpiece.