Importance

Loading Importance Indicators...

Abstract

A self-drilling screw having a head at one end and a forged drilling end configuration at the other. The drilling end configuration comprises a pair of longitudinally extending flutes which are separated by land portions and which extend through a tapered tip end to form two cutting edges. The forging operation is performed in such a way as to promote complete formation of the tip end and that may be achieved by inhibiting material flow away from that tip end or by promoting extrusion of material towards the tip end. The drilling end portion of the screw is of elliptical cross section having a minor axis in the region of 60 to 80% of the major axis, and a fillet is formed in the base of each flute at the tip end portion of the flute. Each fillet has a flat surface arranged generally parallel to the screw axis and angularly relative to the ajacent cutting edge of the tip end. At least one interruption, which mau be a depression of a projection, is formed on each of a plurality of side surfaces of the drilling end portion. Also, each flute may comprise two end to end portions which extend at different angles to the longitudinal axis of the screw.

Loading the Abstract Image...

First Claim