Screw with an improved head structure and punch for forming same

Abstract

A screw includes a shank and a head. The head includes a driving socket having a long slot that extends axially into the head to a depth. A first short recess is defined in a bottom wall defining the long slot and extended along a longitudinal axis of the long slot, the first short recess being narrower yet deeper than the long slot. A second short recess extends along an axis that is normal to the longitudinal axis of the long slot. The second short recess is as deep as the first short recess, the short recesses together defining a cross-shape recess for receiving a Phillips type screw driver, the cross-shape recess including four ends. The driving socket of the head further includes a square recess that is located within an area defined by the four ends of the short recesses, the square recess being adapted to receive a square socket type driver. The square recess extends axially into the head to a depth deeper than the short recesses. The square recess is defined by four sides and includes four apexes and two diagonal axes that intersect at an intersection. The intersection of the diagonal axes of the square recess is coincident with an intersection of the longitudinal axis and the axis that is normal to the longitudinal axis. One of the diagonal axes of the square recess is at an angle with the axis that is normal to the longitudinal axis, the angle being not equal to 45°.

Dependencies are inferred from the claim text.