Patent attributes
A self-drilling expansion fastener is integrally formed of a sheet metal material for locking two or more sheet workpieces together, and includes an expansion structure and a drill structure. The expansion structure has a plurality of internal threads and force-distributing bars. The drill structure has a chip guard for covering a head of the expansion structure, and a drill forward projected from the chip guar for self-drilling a hole. When an externally threaded element is screwed into the expansion structure to mesh with the internal threads, the force-distributing bars are brought to expand outward and are finally compressed into a folded state to thereby tightly lock the sheet workpieces to one another. A method of forming the self-drilling expansion fastener is also disclosed.
