Threaded fastener and threaded fastener clamping tool

摘要

A threaded fastener formed on the middle of a head thereof comprises a concave or convex drive shape adapted to engage with a clamping tool. The drive shape comprises projections equiangularly spaced from one another to extend radially from an axis of the threaded fastener, curved portions formed between the projections to dent toward the axis, and drive surfaces formed between the projections and the curved portions. Clamping forces acting on the drive surfaces are directed toward substantially perpendicular to a straight line passing through the axis and apices of the projections. <IMAGE>