Self-drilling and tapping masonry anchor

Claim 1

In combination with a masonry work structure of predetermined thickness, a self-drilling and tapping masonry anchor comprising an elongate shank body with a drilling tip at one extremity and a radially enlarged driving head at the opposite extremity, the drilling tip including cutting edges defining a first predetermined radial dimension, the shank body including an upper region with a tapping and holding thread formed thereon having a predetermined crest diameter, said thread having an axially spaced root region with a maximum crest diameter which increases gradually from the lowermost region to the uppermost region with the lowermost region defining said predetermined crest diameter, the predetermined crest diameter of said thread thereby defining a second predetermined radial dimension, a lower shank body region forming axial stabilizing and material receiving means directly adjacent the drill tip with a cross-sectional configuration that includes third and fourth predetermined radial dimensions, respectively, defining maximum and minimum radial dimension on said lower shank region, the third, maximum, radial dimension on the lower shank region being defined by a plurality of circumferentially spaced longitudinally extending surfaces, the second predetermined radial dimension being greater than the first predetermined radial dimension thereby permitting at least the crests of the tapping and holding thread to be imbedded in the walls of the hole formed by the drill point, the third predetermined radial dimension being greater than the first predetermined radial dimension and less than the second predetermined radial dimension of the threads so that said lower body accurately sizes the hole and axially stabilizes the anchor during drilling while providing an area between the walls of the hole and the fourth, minimum, radial dimension of the lower shank region into which masonry dust can flow and accumulate, the drilling tip having an axial extent substantially less than the predetermined thickness of the workpiece, the lower shank body having a length substantially equal to said predetermined thickness.