Patent US3881393A successfully refreshed from Google Patents.
US3881393A
Expired / Lapsed
US
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Expansion fastener
Assignee: Individual
•
Filing: 1972-11-27
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Granted: 1975-05-06
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Expires: 1992-11-27
Abstract
Abstract An expansion fastener of the type employing a helical coil which expands radially under force applied in its axial direction, to lock the fastener in a hole. A nut, or the head of a bolt, engages the uppermost turn of the coil, but this turn is free to expand radially along with the rest of the coil to provide additional bearing area in the deepest part of the hole. In one form, the upper rim of the uppermost turn is designed to be upset inward to maintain engagement with the nut as this turn expands under the applied load. In another form, the nut has a lower rim portion which expands radially under the load. In still another form, a washer of dished cross section is disposed between the nut and the uppermost turn, and flattens under load to maintain engagement with both.
Inventors
- 👤 Maxwell S Campbell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 07:00
CPC Classifications
F; F16; F16B; F16B13/00; F16B13/04; F16B13/06; F16B13/061
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
133 words
An expansion fastener comprising: a bolt; a spring coil surrounding said bolt, said coil being a flat helically wound strip having generally cylindrical inner and outer surfaces, and said coil having axially spaced turns all of substantial width in the axial direction and being adapted to expand radially under axial load; a bearing element connected to said bolt and having a generally annular portion, said coil having a turn nearest said bearing element free to expand radially; and connecting means surrounding said annular portion and fixedly connected to said bearing element and said nearest turn, said connecting means being adapted to flatten under axial load and having an outer portion adapted to expand and maintain bearing engagement with said nearest turn and an inner portion adapted to contract and grip said annular portion.
Claim 2
Dependent Claim
133 words
An expansion fastener comprising: a bolt; a spring coil surrounding said bolt, said coil being a flat helically wound strip having generally cylindrical inner and outer surfaces, and said coil having axially spaced turns all of substantial width in the axial direction and being adapted to expand radially under axial load; a bearing element connected to said bolt and having a generally annular portion, said coil having a turn nearest said bearing element free to expand radially; and connecting means surrounding said annular portion and fixedly connected to said bearing element and said nearest turn, said connecting means being adapted to flatten under axial load and having an outer portion adapted to expand and maintain bearing engagement with said nearest turn and an inner portion adapted to contract and grip said annular portion.
Claim 3
Dependent Claim
29 words
An expansion fastener as described in claim 1, said nearest turn having a generally circumferential groove on its interior surface defining an upper rim portion constituting said connecting means.
Claim 4
Dependent Claim
29 words
An expansion fastener as described in claim 1, said connecting means comprising a washer of dished cross-section disposed between and connected to said nearest turn and said bearing element.
Claim 5
Dependent Claim
27 words
An expansion fastener as described in claim 1, said nearest turn having an inwardly bent rim portion connected to said bearing element and constituting said connecting means.
Claim 6
Dependent Claim
65 words
An expansion fastener as described in claim 1, said nearest turn having a generally circumferential groove on its interior surface defining an upper rim portion constituting said connecting means, and said groove being disposed obliquely with respect to the inner edge portion of said connecting means so that the rim portion increases in axial width in the direction toward the turn adjacent said nearest turn.
Claim 7
Dependent Claim
19 words
An expansion fastener as described in claim 1, said bearing member having welding studs welded to said connecting means.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-05 | 1978-11-04 | 1979-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-05 | 1982-11-04 | 1983-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-05 | 1986-11-04 | 1987-05-06 | $7700.00 | Window Closed / Lapsed |