Patent ID: 6419435
Filing Date: 2002-07-16
Classification: F16B

Abstract:
A screw-type self-tapping masonry bolt for fastening an attachment to friable masonry having a hole drilled therein to receive an anchor, the hole having a predetermined diameter, the anchor comprising:a shank having a root section whose diameter is smaller than that of said hole and said shank being integral with a head adapted to be engaged by a torque-producing tool; at least one helical male cutting thread surrounding the root and having a crest diameter exceeding that of said hole whereby when the head is engaged by the tool and bolt is screwed into the hole the male cutting thread then cuts a female thread into the bank of said hole to mechanically retain the bolt and resist pull-out forces to impart holding strength to the bolt, the convolutions of said cutting thread having a helical land or space therebetween, said land or space having a diameter less than the predetermined diameter of said hold; and a hemispherical ridge formed in the helical land or space and having a diameter greater than that of the predetermined diameter of said hole and less than that of the crest diameter of said thread effective to wedge into the bank of the hole.