US 5,205,694 A · Self-tapping screw

Abstract

By modifying a shape of a head part of a screw, an inserting performance when a punching operation is carried out, a fastening performance when the screw is seated, and a finishing process upon completion of fastening against a member to be fastened are improved. A seat surface of the head part is formed in an inverse truncated conical shape with its outer circumference being a curved concave surface and the upper surface of the head part is formed with a spherical concave surface. The head part is provided with a plurality of spot facing projections extending from the seat surface of the small diameter part at the lower portion of the head part adjacent to the screw shaft part along the curved concave surface of the seat surface in a longitudinal direction. The upper surface of the head part formed in the spherical concave surface is provided with chamfered portions in which an opening edge of the engaging groove of a cross-shaped hole is cut in a conical shape.

Claims4

Dependent claims

A screw comprising a screw shaft part, a sharp end integrally formed with the screw shaft part, and a head part integrally formed with the screw shaft part at a side opposite to the sharp end, said head part including a seat part extending to the screw shaft and having a shape of an inverse truncated cone with a curved outer surface, a spherical concave surface at an upper end surface of the head part, and an engaging groove adapted to engage with a screw driver tool, said engaging groove extending inwardly from the spherical concave surface and having chamfered portions with inwardly tapered shapes at an entire edge of the engaging groove so that the screw driver tool can be easily engaged with the engaging groove.

Dependencies are inferred from the claim text.

Self-tapping screw

Life of this patent

Self-tapping screw

Life of this patent

Abstract

Claims4