Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Externally threaded fastener element – e.g. – bolt – screw – etc. – Head driving structure
Patent
1991-11-26
1993-06-15
Lindsey, Rodney M.
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Externally threaded fastener element, e.g., bolt, screw, etc.
Head driving structure
411404, F16B 2300
Patent
active
052192539
ABSTRACT:
A recessed screw having in its head a recess for engaging with a driver bit, with the recess being defined with curved engaging walls and radial or corner grooves. Each engaging wall is a portion of a conical surface slanted inwardly towards a bottom of the recess. Each corner groove extends outwards from the adjacent engaging walls in radial direction. A pair of vertical side walls, lying parallel with the recessed screw's axis define each corner groove. The driver bit has protrusions tightly fittable in the recess, which recess may be a superimposition of two square holes disposed symmetrically with a phase shift of 45.degree. around the axis so as to provide eight corner grooves. Each engaging wall may be formed at a place where the side walls intersect one another. The driver bit may comprise a shank and a bit portion which extends from the shank and formed with eight V-shaped grooves extending axially of the bit so that eight blades are defined each between the two V-shaped grooves. A bottom of each V-shaped groove or a top of each blade may be a curved wall to closely contact with the engaging walls in the recess.
REFERENCES:
patent: 2182568 (1939-12-01), Olson
patent: 2777353 (1957-01-01), Willis
patent: 3604305 (1971-09-01), Dreger
patent: 4228723 (1980-10-01), Cunningham
patent: 4384812 (1983-05-01), Miyagawa
patent: 4646594 (1987-03-01), Tien
Lindsey Rodney M.
Yugenkaisha Shinjo Seisakusho
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