Patent ID: 6250866
Filing Date: 2001-06-26
Classification: F16B

Abstract:
A self-drilling, self-tapping screw for concrete blocks, comprising:a head including a coupler for coupling with a driving tool, a retainer flange and a tapered conical section projecting axially from said flange opposite said structures,a shank integrally extending from said tapered conical section and defining a screw axis, said shank having an unthreaded first portion adjacent said tapered conical section, a second portion including a first spiral thread having a first outer diameter and a second spiral thread having a second outer diameter, said second outer diameter smaller than said first outer diameter and a root diameter, an unthreaded third portion having a length of at least one inch, an outer diameter greater than the root diameter of said second portion but less than said second outer diameter, and terminating in a distal tip having an axial slot, anda carbide insert having a base portion and opposed cutting edges, said insert secured in said slot with said base portion facing said shank and said cutting edges forming a drill tip,wherein said first and second outer diameters taper toward said root diameter over approximately 30% of said second portion adjacent to said third portion.