US4214923A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for treating metal
Assignee: Caterpillar Inc
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Filing: 1978-10-04
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Granted: 1980-07-29
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Expires: 1998-10-04
Abstract
Abstract An element (12) having a chamber (28) such as, for example, a boom (12) of an excavator (10) or a draft tube of a scraper is subject to torsional loading during use of the element (12). Torsional loading creates tensile stresses (T) on the welds (22) of the excavator boom (12), which can lead to weld failure. A method for controllably treating the metal of the element (12) includes heating the element (12) and pressurizing the chamber (28), maintaining the element (12) and chamber (28) at a preselected temperature and pressure (P 1 ), respectively, and cooling the element (12) and depressurizing the chamber (28). The method produces residual compressive stresses (C 2 ) in the metal, such as in the root area (23) of the welds (22) of the excavator boom (12), for increasing fatigue life under torsional loading of the boom (12).
Inventors
- 👤 Robert J. Price
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:26
CPC Classifications
C; C21; C21D; C21D7/00; C21D7/02; C21D7/10; C21D7/12; C21D9/00; C21D9/0068; E; E02; E02F; E02F3/00; E02F3/04; E02F3/28; E02F3/36; E02F3/38; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49805
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
160 words
A method for controllably treating metal of a preselected area (23) of an element (12) having a chamber (28), sidewalls (20) and welds (22) each having a root area (23) and each joining respective sidewalls (20) on to the other, said preselected area (23) being defined by said root areas (23) of said welds (22), comprising: heating said element (12) and pressurizing said chamber (28) to preselecting values; controllably stressing the metal of said preselected area (23) of the element (12) beyond the elastic limit of said metal maintaining said chamber (28) at a preselected pressure (P 1 ) for a preselected period; controllably stress relieving said element (12) by maintaining said element (12) at a preselected temperature while said metal of the preselected area (B) is stressed beyond the elastic limit of said metal; and controllably creating residual stresses in said preselected area (23) of the element (12) by controllably cooling said element (12) and depressurizing said chamber (28).
Claim 2
Independent Claim
160 words
A method for controllably treating metal of a preselected area (23) of an element (12) having a chamber (28), sidewalls (20) and welds (22) each having a root area (23) and each joining respective sidewalls (20) on to the other, said preselected area (23) being defined by said root areas (23) of said welds (22), comprising: heating said element (12) and pressurizing said chamber (28) to preselecting values; controllably stressing the metal of said preselected area (23) of the element (12) beyond the elastic limit of said metal maintaining said chamber (28) at a preselected pressure (P 1 ) for a preselected period; controllably stress relieving said element (12) by maintaining said element (12) at a preselected temperature while said metal of the preselected area (B) is stressed beyond the elastic limit of said metal; and controllably creating residual stresses in said preselected area (23) of the element (12) by controllably cooling said element (12) and depressurizing said chamber (28).
Claim 3
Dependent Claim
31 words
The method, as set forth in claim 1, including the step of controllably passing fluid from the chamber (28) for maintaining said chamber (28) at the preselected pressure (P 1 ).
Claim 4
Dependent Claim
24 words
The method, as set forth in claim 1, wherein the chamber (28) is pressurized to a preselected pressure prior to heating the element (12).
Claim 5
Dependent Claim
24 words
The method, as set forth in claim 1, wherein the element (12) is heated to a preselected temperature prior to pressurizing the chamber (28).
Claim 6
Dependent Claim
43 words
The method, as set forth in claim 1, wherein the pressure to which said chamber (28) is pressurized is of a magnitude sufficient for stressing the metal of said preselected area (23) of the element (12) beyond the elastic limit of said metal.
Claim 7
Dependent Claim
24 words
The method, as set forth in claim 1, wherein the element (12) is cooled to a preselected temperature prior to depressurizing the chamber (28).
Claim 8
Dependent Claim
18 words
The method, as set forth in claim 1, wherein the element (12) is cooled at a preselected rate.
Claim 9
Dependent Claim
21 words
The method, as set forth in claim 1, wherein the chamber (28) is depressurized to a preselected pressure (P 2 ).
Claim 10
Dependent Claim
18 words
The method, as set forth in claim 1, wherein the chamber (28) is depressurized at a preselected rate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-07-29 | 1984-01-28 | 1984-07-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-07-29 | 1988-01-28 | 1988-07-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-07-29 | 1992-01-28 | 1992-07-29 | $7700.00 | Window Closed / Lapsed |