US3796086A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ring pad stress coining
Assignee: McDonnell Douglas Corp
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Filing: 1972-08-02
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Granted: 1974-03-12
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Expires: 1992-08-02
Abstract
Abstract A method for improving the fatigue strength of a metallic structural member and the member having a discontinuity therein. A ring-shaped pad of material spaced about the aperture is coldworked into a plastic state and then allowed to rebound into an elastic state thereby generating a region of residual compressive stress about the aperture which results in a member having improved fatigue strength.
Inventors
- 👤 A Phillips
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:29
CPC Classifications
B; B23; B23P; B23P9/00; B23P9/02; B23P9/025; B21; B21D; B21D22/00; B21D22/02; B21D22/04; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49616; Y10T29/49623; Y10T29/49625
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
134 words
A cold-working period method for improving the fatigue strength of a structural member having a first face and a discontinuity therein said method comprising: forming a first groove in the first face of the structural member adjacent said discontinuity by compressively displacing material of the structural member toward said discontinuity and away from said first face, said displacement being sufficient to create residual radial and circumferential compressive stress in the area between the periphery of said groove and the edge of the discontinuity and to create residual compressive stress in the area of said first groove; said first groove having a planar bottom and arcuate side walls adjacent the discontinuity which are curved upwardly; and said groove side walls being tangent to and extending from said groove bottom to said structural member first face.
Claim 2
Dependent Claim
134 words
A cold-working period method for improving the fatigue strength of a structural member having a first face and a discontinuity therein said method comprising: forming a first groove in the first face of the structural member adjacent said discontinuity by compressively displacing material of the structural member toward said discontinuity and away from said first face, said displacement being sufficient to create residual radial and circumferential compressive stress in the area between the periphery of said groove and the edge of the discontinuity and to create residual compressive stress in the area of said first groove; said first groove having a planar bottom and arcuate side walls adjacent the discontinuity which are curved upwardly; and said groove side walls being tangent to and extending from said groove bottom to said structural member first face.
Claim 3
Dependent Claim
38 words
The method defined in claim 1 wherein said groove bottom has a surface area larger than the surface area of said groove side wall and said groove walls in cross-section each forming arcs which are less than 45*.
Claim 4
Dependent Claim
42 words
The method defined in claim 1 wherein the structural member has a second face opposite the first, said method further comprising: forming a second groove similar to said first groove in the second face of the structural member opposite said first groove.
Claim 5
Dependent Claim
28 words
The method defined in claim 1 wherein the discontinuity is a hole passing through the structural member, said method further comprising: forming said groove concentrically about the hole.
Claim 6
Dependent Claim
26 words
The method defined in claim 1 wherein the depth of said first groove is about equal to the depth said structural member can be displaced elastically.
Claim 7
Dependent Claim
21 words
The method defined in claim 4 wherein said hole is not restrained from deformation when said first groove is being formed.
References Cited (Backward Citations)
US2909281A
Cited
US3355930A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-11 | 1977-09-10 | 1978-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-11 | 1981-09-10 | 1982-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-11 | 1985-09-10 | 1986-03-12 | $7700.00 | Window Closed / Lapsed |