Fastener having multiple lobed thread

摘要

A threaded fastener includes a lead (18) having bosses (24) separated from one another by bases along the thread crest. The lead-in and lead-out profiles of the bosses, and other features of the bosses and bases may differ from one another along the fastener shank (16). The lead-in and lead out profiles may have linear and non-linear surfaces. The lead-in and lead-out profiles may have cutting edges angled toward the direction of propagation of the bosses. The boss profiles may be selected to reduce insertion torque and to provide excellent resistance to pullout. The fastener may be formed by roll threading via a tool made by a plunge EDM process.