Patent US3578940A successfully refreshed from Google Patents.
US3578940A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Welding process
Assignee: Meritor Inc
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Filing: 1969-02-20
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Granted: 1971-05-18
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Expires: 1989-02-20
Abstract
Abstract A welding apparatus and method for spot welding a first metal workpiece having a plastic-covered surface to a second metal workpiece. The two workpieces are placed in metal-to-metal engagement and clamped between the electrodes of two aligned welding guns, a first electrode engaging the plastic surface of the first workpiece and a second electrode engaging the second workpiece. At a point spaced from the second electrode, the metal of the second workpiece is engaged by a contact member between which and the second electrode an electric current can flow through the metal. The second electrode is connected to one terminal of a welding-current source the other terminal of which is connectable through appropriate switch means alternatively to the contact member or to the first electrode. With the contact member connected to the current source heat generated by current flow through the metal of the workpieces softens the plastic to enable the first electrode to penetrate it and engage the metal substrate. Thereupon, the switch means is operated to disconnect the contact member from the power source and connect the first electrode thereto, thus permitting welding current to flow between the two electrodes through the metal. A timing mechanism is provided to control automatically the supply of current and the operation of the welding guns and switch means.
Inventors
- 👤 Oran J Sands
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 01:20
CPC Classifications
B; B23; B23K; B23K11/00; B23K11/16; B23K11/163
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
214 words
A method of spot welding a metal workpiece to the surface of a second metal workpiece, wherein at least one of said workpieces has one of its sides covered with a thermoplastic coating, comprising the steps of softening said coating at the weld site by heat generated by a first electric current flowing from a current source through a first welding electrode and a contact member and at least one of the workpieces in a direction generally perpendicular to the thickness of the workpieces, said first electrode and contact member being in engagement with a metal surface of at least one of said workpieces, forcing a second welding electrode against coating on the workpieces, not engaged by said first electrode, at the desired location of the weld while said coating is in a softened state, thereby puncturing the plastic coating and disposing both of said electrodes in contact with the metal surfaces of said workpieces, and then causing a second electric current from said current source to flow between said electrodes and through the two workpieces in the direction of their thicknesses, said second electric current not being initiated until the flow of said first current is terminated and said second electrode being disconnected from the current source during its penetration of said coating.
Claim 2
Independent Claim
214 words
A method of spot welding a metal workpiece to the surface of a second metal workpiece, wherein at least one of said workpieces has one of its sides covered with a thermoplastic coating, comprising the steps of softening said coating at the weld site by heat generated by a first electric current flowing from a current source through a first welding electrode and a contact member and at least one of the workpieces in a direction generally perpendicular to the thickness of the workpieces, said first electrode and contact member being in engagement with a metal surface of at least one of said workpieces, forcing a second welding electrode against coating on the workpieces, not engaged by said first electrode, at the desired location of the weld while said coating is in a softened state, thereby puncturing the plastic coating and disposing both of said electrodes in contact with the metal surfaces of said workpieces, and then causing a second electric current from said current source to flow between said electrodes and through the two workpieces in the direction of their thicknesses, said second electric current not being initiated until the flow of said first current is terminated and said second electrode being disconnected from the current source during its penetration of said coating.
Claim 3
Independent Claim
172 words
A method of spot welding a metal workpiece to the bare metal surface of another metal workpiece whose opposite surface is covered with a thermoplastic coating, comprising the steps of moving a first and second electrode into alignment with each other and into bearing contact with said coating and metal workpiece, moving a contact member into contact with one of said metal workpiece and another workpiece, softening said coating interposed between said first and second electrodes by heat generated by a first electric current flowing from a current source through said second electrode and contact member, forcing said first electrode through said coating to form an opening therein while said coating is in a softened state and to dispose said first electrode in contact with the metal of said another workpiece, and after said first electrode is in contact with the metal of said another workpiece causing a second electric current to flow from said current source between said first and second electrodes through the two workpieces to weld said workpieces together.
Claim 4
Independent Claim
172 words
A method of spot welding a metal workpiece to the bare metal surface of another metal workpiece whose opposite surface is covered with a thermoplastic coating, comprising the steps of moving a first and second electrode into alignment with each other and into bearing contact with said coating and metal workpiece, moving a contact member into contact with one of said metal workpiece and another workpiece, softening said coating interposed between said first and second electrodes by heat generated by a first electric current flowing from a current source through said second electrode and contact member, forcing said first electrode through said coating to form an opening therein while said coating is in a softened state and to dispose said first electrode in contact with the metal of said another workpiece, and after said first electrode is in contact with the metal of said another workpiece causing a second electric current to flow from said current source between said first and second electrodes through the two workpieces to weld said workpieces together.
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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) | 1974-05-17 | 1974-11-16 | 1975-05-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-17 | 1978-11-16 | 1979-05-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-17 | 1982-11-16 | 1983-05-18 | $7700.00 | Window Closed / Lapsed |