Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Externally threaded fastener element – e.g. – bolt – screw – etc. – Head having counter-sinking means
Patent
1987-11-09
1989-06-27
Wilson, Neill R.
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Externally threaded fastener element, e.g., bolt, screw, etc.
Head having counter-sinking means
411417, 411386, F16B 2300, F16B 3506
Patent
active
048424676
ABSTRACT:
A self-tapping screw for use on concrete and masonry structures is disclosed. The screw has a helically threaded shank of uniform diameter. The crest diameter of the helical thread on the shank has a taper which increases gradually from the tip or entering end of the shank for a predetermined distance along the shank and then has a uniform diameter over the remaining portion of the helical thread. The helical threads have a spacing of 5-8 threads per inch for screw sizes in the range of 1/2 to 3/16 inch. Thread cutting notches are formed in the threads over at least the tapered portion thereof. The screw is hardened to a Rockwell "C" hardness of 48 or greater.
REFERENCES:
patent: 1526182 (1925-02-01), Rosenberg
patent: 2096937 (1937-10-01), McManus
patent: 2293930 (1942-08-01), Braendel
patent: 3376780 (1968-04-01), Tanczyn
patent: 3748949 (1973-07-01), Dreger
patent: 3902399 (1975-09-01), Yotti
patent: 3937119 (1976-02-01), Ernst
patent: 4439077 (1984-03-01), Godsted
Wilson Neill R.
Yamashina Seiko-sho, Ltd.
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