US3828422A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making fatigue resistant fastener joint
Assignee: Boeing Co
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Filing: 1973-05-03
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Granted: 1974-08-13
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Expires: 1993-05-03
Abstract
Abstract A flush head fastener pin for use in aircraft structural joints which are countersunk for surface flushness. The pin is shaped and adapted to preload the joint material surrounding the countersink to create a predetermined residual stress pattern in that region for improvement of fatigue life. Preferred embodiments of a straight shank bolt, a tapered shank bolt, and a rivet are presented. Each pin embodiment has a 70* conical head and a concave transition portion of specified radius and smoothness interconnecting the head with the shank. The 70* head and transition portion cooperate to conformably deform and preload the countersunk region of the hole, which is preferably provided with a convex surface of specified radius at the base of the countersink, and a conical surface having a greater cone angle than that of the pin. The straight shank bolt embodiment further discloses a hardened convex lead-in portion of specified shape and smoothness extending between the shank and the threads to prevent galling of the hole during installation of the bolt.
Inventors
- 👤 H Schmitt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 07:22
CPC Classifications
F; F16; F16B; F16B4/00; F16B4/004; F16B19/00; F16B31/00; F16B31/06; F16B35/00; F16B35/04; F16B35/06; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49826; Y10T29/49908; Y10T29/49938; Y10T29/49943; Y10T29/49945; Y10T29/49947; Y10T29/49948
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
188 words
A method of manufacturing a joint which includes an overlapping pair of structural members connected by a conical head fastener having a given cone angle ranging between 60* and 85*, a predetermined shank size, and a concave surface having a nominal radius of curvature of at least 15 percent of the maximum diameter of said shank interconnecting said head and said shank comprising the steps of: 1. machining an aligned close tolerance hole through said overlapping pair of structural members, 2. machining a countersink in the face of one of said members concentrically with said hole to a countersink cone angle which is different from the given cone angle of said fastener, 3. machining a convex surface having a radius of at least 0.015 inch tangent to and between the surfaces of said hole and said countersink, 4. inserting said conical head fastener in the countersink and the hole, 5. applying force to said fastener to seat the fastener in the hole and expand the material surrounding said hole and said countersink to establish a prestress condition which is substantially uniform along the entire length of the fastener.
Claim 2
Independent Claim
188 words
A method of manufacturing a joint which includes an overlapping pair of structural members connected by a conical head fastener having a given cone angle ranging between 60* and 85*, a predetermined shank size, and a concave surface having a nominal radius of curvature of at least 15 percent of the maximum diameter of said shank interconnecting said head and said shank comprising the steps of: 1. machining an aligned close tolerance hole through said overlapping pair of structural members, 2. machining a countersink in the face of one of said members concentrically with said hole to a countersink cone angle which is different from the given cone angle of said fastener, 3. machining a convex surface having a radius of at least 0.015 inch tangent to and between the surfaces of said hole and said countersink, 4. inserting said conical head fastener in the countersink and the hole, 5. applying force to said fastener to seat the fastener in the hole and expand the material surrounding said hole and said countersink to establish a prestress condition which is substantially uniform along the entire length of the fastener.
Claim 3
Dependent Claim
31 words
machining a countersink in the face of one of said members concentrically with said hole to a countersink cone angle which is different from the given cone angle of said fastener,
Claim 4
Dependent Claim
31 words
machining a countersink in the face of one of said members concentrically with said hole to a countersink cone angle which is different from the given cone angle of said fastener,
Claim 5
Dependent Claim
56 words
The method of claim 1 wherein said aligned close tolerance hole is machined such that it is correspondingly smaller than said predetermined shank size by a predetermined amount exceeding 0.001 inch and which includes the step of torquing a nut means onto one end of said fastener in order to retain said fastener in said hole.
Claim 6
Dependent Claim
64 words
The method of claim 1 wherein said aligned close tolerance hole is machined such that it is substantially the same size as said predetermined shank size and wherein the step of applying force to said fastener includes swaging an end portion of said shank onto the surface of one of the structural members in order to secure and retain said fastener in said hole.
Claim 7
Dependent Claim
24 words
machining a convex surface having a radius of at least 0.015 inch tangent to and between the surfaces of said hole and said countersink,
Claim 8
Dependent Claim
24 words
machining a convex surface having a radius of at least 0.015 inch tangent to and between the surfaces of said hole and said countersink,
Claim 9
Dependent Claim
11 words
inserting said conical head fastener in the countersink and the hole,
Claim 10
Dependent Claim
11 words
inserting said conical head fastener in the countersink and the hole,
Claim 11
Dependent Claim
38 words
applying force to said fastener to seat the fastener in the hole and expand the material surrounding said hole and said countersink to establish a prestress condition which is substantially uniform along the entire length of the fastener.
Claim 12
Dependent Claim
38 words
applying force to said fastener to seat the fastener in the hole and expand the material surrounding said hole and said countersink to establish a prestress condition which is substantially uniform along the entire length of the fastener.
References Cited (Backward Citations)
GB188917569A
Cited
US2018913A
Cited
US3034611A
Cited
US3270410A
Cited
US3369440A
Cited
US3418012A
Cited
US3578367A
Cited
US3512446A
Cited
US3630116A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-12 | 1978-02-11 | 1978-08-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-12 | 1982-02-11 | 1982-08-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-12 | 1986-02-11 | 1986-08-13 | $7700.00 | Window Closed / Lapsed |