US4202244A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Recessed head screw
Assignee: Technofast Inc
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Filing: 1978-07-26
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Granted: 1980-05-13
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Expires: 1998-07-26
Abstract
Abstract A screw head recess includes a generally frusto-conical central socket and radial slots interconnected by concave sections of the socket. Each slot is defined by two opposed wall surfaces which intersect with a bottom surface which slopes radially inwardly and downwardly along the axis of the screw. At least a portion of the junction between one sidewall and the bottom surface is curved to produce a camming surface for frictional engagement between the screw and a driving tool sufficient to provide a temporary stick-fit between the screw and the tool.
Inventors
- 👤 Charles E. Gutshall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 07:32
CPC Classifications
F; F16; F16B; F16B23/00; F16B23/0007; F16B23/0023
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
165 words
In a screw having a head provided with a cruciform recess comprising a plurality of radially extending slots, said recess being adapted to received a driving tool provided with flutes which engage said slots, the improvement wherein: said recess comprises a generally frusto-conical central socket portion having sidewall concave sections interconnecting adjacent slots and a generally spherical bottom surface; each of said slots comprises a pair of opposed sidewalls and a generally sloping bottom wall interconnecting said sidewalls, said opposed sidewalls being symmetrically inclined relative to the axis of said screw, said bottom wall of each of said seat joining a single one of said sidewalls in a concave camming surface extending along at least a portion of the depth of said slot; whereby on insertion of said driving tool, a flute of said tool which enters a slot in said head is cammed between said concave surface and the opposite sidewall of said slot, creating a frictional engagement between said tool and said screw.
Claim 2
Dependent Claim
165 words
In a screw having a head provided with a cruciform recess comprising a plurality of radially extending slots, said recess being adapted to received a driving tool provided with flutes which engage said slots, the improvement wherein: said recess comprises a generally frusto-conical central socket portion having sidewall concave sections interconnecting adjacent slots and a generally spherical bottom surface; each of said slots comprises a pair of opposed sidewalls and a generally sloping bottom wall interconnecting said sidewalls, said opposed sidewalls being symmetrically inclined relative to the axis of said screw, said bottom wall of each of said seat joining a single one of said sidewalls in a concave camming surface extending along at least a portion of the depth of said slot; whereby on insertion of said driving tool, a flute of said tool which enters a slot in said head is cammed between said concave surface and the opposite sidewall of said slot, creating a frictional engagement between said tool and said screw.
Claim 3
Dependent Claim
26 words
A screw in accordance with claim wherein said head is provided with an annular indent adjacent the periphery of said central socket portion of said recess.
Claim 4
Dependent Claim
22 words
A screw in accordance with claim 1 wherein said sidewalls of each slot are generally parallel to the axis of said screw.
Claim 5
Dependent Claim
26 words
A screw in accordance with claim 1, in which a cylindrical surface interconnects said spherical bottom surface and said conical sidewall of said central socket portion.
References Cited (Backward Citations)
US2474994A
Cited
US2397216A
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US2556155A
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US3295572A
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US4084478A
Cited
FR2356046A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-05-13 | 1983-11-12 | 1984-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-05-13 | 1987-11-12 | 1988-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-05-13 | 1991-11-12 | 1992-05-13 | $7700.00 | Window Closed / Lapsed |