US4229875A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of prestressing bolts
Assignee: SPS Technologies LLC
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Filing: 1978-12-26
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Granted: 1980-10-28
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Expires: 1998-12-26
Abstract
Abstract A fatigue resistant bolt, and method for making same, is disclosed. Bolts which are tightened to very high loads and are subjected to a dynamic environment are particularly subject to fatigue failure. It has been found that a bolt with fatigue resistant properties may be manufactured if its threads are formed while it is subjected to its design load. In another embodiment of the invention it has been found that the fatigue properties of the fillet at the bolt head and shank juncture may be significantly increased if the fillet is cold worked while the bolt is subjected to its design load.
Inventors
- 👤 Corey F. Crispell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:24
CPC Classifications
B; B21; B21K; B21K1/00; B21K1/56; B21K1/44; B21K1/46; F; F16; F16B; F16B31/00; F16B31/06; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49826; Y10T29/49863; Y10T29/49874
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
52 words
The method of forming threads in the shank of a bolt which comprises: exerting a force on the shank of the bolt placing it in tension; forming the threads in the shank while it is in tension; and releasing the force after the threads have been formed; whereby prestressed threads are provided.
Claim 2
Independent Claim
52 words
The method of forming threads in the shank of a bolt which comprises: exerting a force on the shank of the bolt placing it in tension; forming the threads in the shank while it is in tension; and releasing the force after the threads have been formed; whereby prestressed threads are provided.
Claim 3
Dependent Claim
18 words
The method of claim 1 wherein the tension is substantially equal to the design load of the bolt.
Claim 4
Dependent Claim
12 words
The method of claim 1 wherein said threads are formed by rolling.
Claim 5
Dependent Claim
12 words
The method of claim 1 wherein said threads are formed by machining.
Claim 6
Dependent Claim
20 words
The method of claim 3 or 4 wherein said tension is substantially equal to the design load of the bolt.
Claim 7
Independent Claim
56 words
The method of cold working threads in the shank of a bolt which comprises: exerting a force on the shank of the bolt placing it in tension; cold working the threads by rerolling them while the shank is in tension; and releasing the force after the threads have been cold worked; whereby prestressed threads are provided.
Claim 8
Independent Claim
56 words
The method of cold working threads in the shank of a bolt which comprises: exerting a force on the shank of the bolt placing it in tension; cold working the threads by rerolling them while the shank is in tension; and releasing the force after the threads have been cold worked; whereby prestressed threads are provided.
Claim 9
Dependent Claim
18 words
The method of claim 6 wherein the force is substantially equal to the design load of the bolt.
Claim 10
Independent Claim
38 words
The method of claims 1 or 6 wherein the bolt includes a fillet at the juncture of the head and shank, and which further includes the step of cold working the fillet while the bolt is in tension.
Claim 11
Dependent Claim
18 words
The method of claim 8 wherein said tension is substantially equal to the design load of the bolt.
Claim 12
Dependent Claim
13 words
The method of claim 9 wherein said fillet is cold worked by rolling.
Claim 13
Dependent Claim
18 words
The method of claim 10 wherein said tension is substantially equal to the design load of the bolt.
Claim 14
Independent Claim
63 words
The method of cold working a fillet which is formed at the juncture of the head and shank of a bolt which comprises: exerting a force on the shank of the bolt placing it in tension; cold rolling the fillet while the bolt is in tension; and releasing the force after the fillet has been cold rolled, whereby a prestressed fillet is provided.
Claim 15
Independent Claim
63 words
The method of cold working a fillet which is formed at the juncture of the head and shank of a bolt which comprises: exerting a force on the shank of the bolt placing it in tension; cold rolling the fillet while the bolt is in tension; and releasing the force after the fillet has been cold rolled, whereby a prestressed fillet is provided.
Claim 16
Dependent Claim
18 words
The method of claim 12 wherein said tension is substantially equal to the design load of the bolt.
Claim 17
Independent Claim
122 words
The method of forming prestressed threads in a bolt, having a head and an unthreaded shank, which comprises: forming first threads in the end of the shank; placing the bolt in a head supporting means; engaging the first threads with mating threads of an adapter; exerting a force between the adapter and the head supporting means to place the bolt in tension; forming secured threads in the shank, adjacent the first threads, while the bolt is in tension; releasing the tension force after the second threads have been formed; disengaging the first threads from the adapter; removing the bolt from the head supporting means; removing that portion of the shank in which the first threads were formed; and pointing the bolt shank.
Claim 18
Independent Claim
122 words
The method of forming prestressed threads in a bolt, having a head and an unthreaded shank, which comprises: forming first threads in the end of the shank; placing the bolt in a head supporting means; engaging the first threads with mating threads of an adapter; exerting a force between the adapter and the head supporting means to place the bolt in tension; forming secured threads in the shank, adjacent the first threads, while the bolt is in tension; releasing the tension force after the second threads have been formed; disengaging the first threads from the adapter; removing the bolt from the head supporting means; removing that portion of the shank in which the first threads were formed; and pointing the bolt shank.
Claim 19
Dependent Claim
18 words
The method of claim 14 wherein the force is substantially equal to the design load of the bolt.
Claim 20
Dependent Claim
13 words
The method of claim 14 wherein the second threads are formed by rolling.
Claim 21
Dependent Claim
13 words
The method of claim 14 wherein the second threads are formed by machining.
Claim 22
Dependent Claim
20 words
The method of claim 16 or 17 wherein the force is substantially equal to the design load of the bolt.
References Cited (Backward Citations)
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Cited
GB442984A
Cited
US2341469A
Cited
GB1321845A
Cited
US4023225A
Cited
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Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-10-28 | 1984-04-28 | 1984-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-10-28 | 1988-04-28 | 1988-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-10-28 | 1992-04-28 | 1992-10-28 | $7700.00 | Window Closed / Lapsed |