Locking self-tapping threaded stud insert assembly and method

Claim 1

For use in conjunction with a cylindrical bore formed in a body, a self-tapping threaded stud insert assembly for installation in the cylindrical bore, the material of the body being relatively softer than the material of said insert assembly, said assembly comprising an elongated shank including an enlarged cylindrical inner end portion of a length less than the depth of the bore and a reduced diameter cylindrical outer end portion forming a continuation of said inner end portion, said inner and outer end portions being disposed in coaxial alignment, an outwardly facing annular shoulder formed at the junction of said inner and outer end portions, a self-tapping cutting thread portion beginning at said inner end and extending helically about the circumference of said inner end portion for the self-tapping of threads within the bore to a greater depth than the length of the inner end, a retaining thread portion beginning at said outer end and extending helically about the circumference of said outer end portion, and an elongated tubular locking sleeve having an internal bore slidable over said outer end portion, a locking shoulder at the lead end of said sleeve adapted to engage said annular shoulder, drive means formed in the trailing end of said sleeve, the outer circumference of said sleeve being formed with a helical thread matching the thread of said inner end portion of said shank for substantially full engagement with the threads tapped in the bore by the inner end.