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US 5,188,496 AGranted
Self-tapping screw-type masonry anchor
OwnerLouis N. Giannuzziinventor
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OwnerLouis N. Giannuzziinventor
Estimating the term…
A self-tapping screw-type masonry anchor which when turned into a hole drilled in a masonry structure to secure an object thereto is then highly resistant to pull-out forces. The anchor is fabricated of a metal whose hardness is such that when it rubs against a masonry surface it is abraded and worn thereby. The anchor includes a head engageable by a torque-producing tool to rotate the anchor, and a shank extending therefrom provided with a root section surrounded by a helical male cutting thread whose series of convolutions have sharp crests and extend from the leading to the trailing end of the root section. The crests have diameters greater than that of the hole which decrease progressively from the leading to the trailing end to create a reverse taper. When the anchor is rotated to cause it to enter the hole and tap its wall, the sharp crest at the leading end of the cutting thread experiences a high degree of wear and blunting, the degree of crest wear diminishing progressively toward the trailing end to effectively erase the taper and produce a male thread in the shank of substantially uniform diameter and a mating female internal thread in the wall of the hole, this relationship resulting in high resistance to loosening of the anchor.
A self-tapping, screw-type masonry anchor insertable in a hole having a predetermined diameter bored in a masonry structure to secure an object thereto, said anchor being fabricated of a metal whose hardness is such that when it rubs against a masonry surface it is abraded and worn thereby, said anchor comprising:
A self-tapping, screw-type masonry anchor insertable in a hole bored in a masonry structure to secure an object thereto, said anchor being fabricated of a metal whose hardness is such that when it rubs against a masonry surface it is abraded and worn thereby, said anchor comprising a head engageable by a tool to rotate the anchor and a shank extending from the head provided with an external cutting thread formed by a series of convolutions having sharp crests whose diameters decrease progressively to define with respect to the head a reverse taper, whereby when the tool acts to rotate the anchor to cause the cutting thread to tap its way into the wall of the hole, the sharp crests then experience respective degrees of wear and blunting that effectively erase the reverse taper to create on the shank an external male thread whose crests are of substantially uniform diameter and to create on the wall of the hole a complementary internal female thread resulting in high resistance to loosening of the anchor.
A single-piece, self-tapping, screw-type masonry anchor insertable in a hole bored in a substrate to secure an object thereto, said anchor being fabricated of a material which, when it rubs against a surface of the substrate is abraded and worn thereby, said anchor comprising a head engageable by a tool to rotate the anchor and a shank extending from the head provided with an external cutting thread formed by a series of convolutions having crests whose diameters decrease progressively to define with respect to the head a reverse taper, whereby when the tool acts to rotate the anchor to cause the cutting thread to tap its way into the wall of the hole, the crests then experience respective degrees of wear to create on the shank an external male thread whose crests are of substantially uniform diameter and to create on the wall of the hole a complementary internal female thread resulting in high resistance to loosening of the anchor.
Dependencies are inferred from the claim text.