US4384812A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Screw and screw forming tool
Assignee: Miyagawa Kinzoku Kogyo Co Ltd
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Filing: 1980-03-31
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Granted: 1983-05-24
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Expires: 2000-03-31
Abstract
Abstract A screw having a star-shaped socket hole in the top surface of the screw head in the form of two equilateral octagons which are disposed between a regular octagon and a regular square inscribed in the regular octagon and which are placed one upon another in concentric and out-of-phase relation with a phase shift of about 45° so that there are eight convex regions which alternate with eight concave regions. A tool for forming the same is also disclosed.
Inventors
- 👤 Einosuke Miyagawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 00:25
CPC Classifications
F; F16; F16B; F16B23/00; F16B23/0076; F16B23/0092
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
74 words
A screw characterized in that the top surface of the screw head is formed with a star-shaped socket hole in the form of two equilateral octagons which are disposed between a regular octagon and a regular square inscribed in said regular octagon and which are placed one upon another in concentric and out-of-phase relation with a phase shift of about 45° so that there are eight convex regions which alternate with eight concave regions.
Claim 2
Dependent Claim
74 words
A screw characterized in that the top surface of the screw head is formed with a star-shaped socket hole in the form of two equilateral octagons which are disposed between a regular octagon and a regular square inscribed in said regular octagon and which are placed one upon another in concentric and out-of-phase relation with a phase shift of about 45° so that there are eight convex regions which alternate with eight concave regions.
Claim 3
Dependent Claim
114 words
A screw as set forth in claim 1, characterized in that the eight convex regions extending toward the center of the star-shaped socket hole have an amount of projection which is proportional to the diameter of the socket hole, in that the angle formed between the adjoining lateral walls of each convex region is at least 135° and the vertex of each convex region is formed with an arcuate surface having a radius of 0.01-0.2 times the length of the diagonal lines of the socket hole, and in that the angle formed between the adjoining lateral walls of each of the eight concave regions alternating with the eight convex regions is at least 90°.
Claim 4
Dependent Claim
56 words
A screw as set forth in any one of claims 1 or 2 characterized in that the inner wall surface of the star-shaped socket hole is tapered at an angle of 6°-1° toward the bottom and the bottom wall has a space for facilitating the insertion of a thing to be fitted in the socket hole.
Claim 5
Dependent Claim
45 words
A screw as set forth in any one of claims 1 or 2 characterized in that the depth of the star-shaped socket hole is less than 1.5 times the length of a diagonal line of the socket hole considered from corner-to-corner of the regular square.
Claim 6
Dependent Claim
42 words
A screw as set forth in any one of claims 1 or 2 characterized in that the top surface of the screw head and the star-shaped socket hole are connected together by a chamfered portion of arcuate cross-section having a small diameter.
Claim 7
Dependent Claim
75 words
A screw forming tool characterized in that it comprises a punch whose end surface is formed with a star-shaped projection in the form of two equilaterial octagons which are disposed between a regular octagon and a regular square inscribed in said regular octagon and which are placed one upon another in concentric and out-of-phase relation with a phase shift of about 45° so that there are eight convex regions which alternate with eight concave regions.
Claim 8
Dependent Claim
75 words
A screw forming tool characterized in that it comprises a punch whose end surface is formed with a star-shaped projection in the form of two equilaterial octagons which are disposed between a regular octagon and a regular square inscribed in said regular octagon and which are placed one upon another in concentric and out-of-phase relation with a phase shift of about 45° so that there are eight convex regions which alternate with eight concave regions.
References Cited (Backward Citations)
US2083092A
Cited
FR1009061A
Cited
US2914984A
Cited
FR78328E
Cited
US3190169A
Cited
US3400626A
Cited
US3604305A
Cited
US3656397A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-05-23 | 1986-11-22 | 1987-05-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-23 | 1990-11-22 | 1991-05-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-23 | 1994-11-22 | 1995-05-24 | $7700.00 | Window Closed / Lapsed |