US4972047A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Resistance welding of aluminium
Assignee: Novelis Inc Canada
•
Filing: 1988-10-04
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Granted: 1990-11-20
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Expires: 2008-10-04
Abstract
Abstract Electrodes used for spot welding of aluminium workpieces are improved by a combination of steps: (a) A roughened surface is formed on the electrode tip, preferably to an average roughness depth of 12 to 30 microns. (b) also an artificial protective coating, e.g. a chromate-based coating or an anodic oxide film, is applied to the workpieces. (c) Optionally the nugget diameter in the initial welding set-up is arranged to be not more than 15% greater than the minimum acceptable. Features (a) and (b) act synergistically to increase the service life of the electrodes, typically to more than 2000 welds.
Inventors
- 👤 Mark W. Puddle
- 👤 Nigel C. Davies
- 👤 Peter M. Bullivant-Clark
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 15:52
CPC Classifications
B; B23; B23K; B23K35/00; B23K35/02; B23K35/0205; B23K11/00; B23K11/16; B23K11/18
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
67 words
In resistance welding of aluminium workpieces, a method of increasing the service life of a welding electrode having an uncoated electrode tip, by: (a) forming on the electrode tip a roughened surface having an average roughness depth Rz of at least 10 μm, and (b) providing an artificially applied strongly adherent non-metallic coating on the surface of the aluminium workpieces at the location of the intended weld.
Claim 2
Dependent Claim
67 words
In resistance welding of aluminium workpieces, a method of increasing the service life of a welding electrode having an uncoated electrode tip, by: (a) forming on the electrode tip a roughened surface having an average roughness depth Rz of at least 10 μm, and (b) providing an artificially applied strongly adherent non-metallic coating on the surface of the aluminium workpieces at the location of the intended weld.
Claim 3
Dependent Claim
15 words
A method as claimed in claim 1, wherein the resistance welding is resistance spot welding.
Claim 4
Dependent Claim
55 words
A method as claimed in claim 2, wherein the aluminium workpieces have a predetermined thickness such that successful spot welding requires formation of a weld nugget of predetermined minimum diameter, and the initial welding conditions are arranged to form a weld nugget having a diameter not more than 15% greater than the said minimum diameter.
Claim 5
Dependent Claim
26 words
A method as claimed in claim 1, wherein the electrode is of a copper-based alloy having an average roughness depth Rz of at least 10 microns.
Claim 6
Dependent Claim
18 words
A method as claimed in claim 4, wherein the average roughness depth is from 12 to 30 microns.
Claim 7
Dependent Claim
25 words
A method as claimed in claim 1, wherein the adherent coating is applied at a dry weight of from 0.01 to 1.0 g/m 2 .
Claim 8
Dependent Claim
25 words
A method as claimed in claim 6, wherein the adherent coating is applied at a dry weight of from 0.03 to 0.2 g/m 2 .
Claim 9
Dependent Claim
21 words
A method as claimed in claim 1, wherein the adherent coating is applied uniformly to the entire surfaces of the workpieces.
Claim 10
Dependent Claim
19 words
A method as claimed in claim 1, wherein the adherent coating contains at least 5% by weight of chronium.
Claim 11
Dependent Claim
19 words
A method as claimed in claim 1, wherein the service life of the electrodes is at least 2000 welds.
References Cited (Backward Citations)
GB1235661A
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US3751626A
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US4044220A
Cited
GB1554297A
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US4591687A
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GB2139538A
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GB2139540A
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EP0153149A2
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US4633054A
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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) | 1993-11-19 | 1994-05-21 | 1994-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-11-19 | 1998-05-21 | 1998-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-11-19 | 2002-05-21 | 2002-11-20 | $7700.00 | Window Closed / Lapsed |