Patent US4972047A successfully refreshed from Google Patents.
US4972047A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Resistance welding of aluminium
Assignee: Novelis Inc Canada
•
Filing: 1988-10-04
•
Granted: 1990-11-20
•
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 20:15
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
Cited
US3751626A
Cited
US4044220A
Cited
GB1554297A
Cited
US4591687A
Cited
GB2139538A
Cited
GB2139540A
Cited
EP0153149A2
Cited
US4633054A
Cited
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 |