Patent US3781508A successfully refreshed from Google Patents.
US3781508A
Expired / Lapsed
US
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Apparatus for plasma welding
Assignee: Messer Griesheim GmbH
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Filing: 1971-09-13
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Granted: 1973-12-25
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Expires: 1991-09-13
Abstract
Abstract Plasma welding of light-metal workpieces and materials subject to oxidation is carried out using square-wave alternating current. The energization circuit comprises a bridge of controllable rectifier-type elements, the welding electrode network being positioned in a diagonal of the bridge while a direct-current source with a declining characteristic is connected across the other diagonal.
Inventors
- 👤 H Dauer
- 👤 P Hildebrandt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:52
CPC Classifications
B; B23; B23K; B23K10/00; B23K10/02
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
95 words
A plasma-welding system, comprising: four controllable semiconductor devices connected in a bridge support with each of The devices constituting a branch of the bridge; a direct-current source connected in a first diagonal of the bridge and constituting the sole welding-current source; a plasma-welding torch having an electrode spacedly juxtaposed with a workpiece, said electrode and said workpiece being connected across said bridge as the second diagonal thereof; and a trigger network connected to said semiconductor device for selectively rendering same conductive to apply a rectangular wave form alternating current across said electrode and said workpiece.
Claim 2
Dependent Claim
95 words
A plasma-welding system, comprising: four controllable semiconductor devices connected in a bridge support with each of The devices constituting a branch of the bridge; a direct-current source connected in a first diagonal of the bridge and constituting the sole welding-current source; a plasma-welding torch having an electrode spacedly juxtaposed with a workpiece, said electrode and said workpiece being connected across said bridge as the second diagonal thereof; and a trigger network connected to said semiconductor device for selectively rendering same conductive to apply a rectangular wave form alternating current across said electrode and said workpiece.
Claim 3
Dependent Claim
64 words
The plasma-welding system defined in claim 1 wherein each of said devices is a three terminal solid-state element having a pair of principal electrodes constituting the respective branch of said bridge, and control terminals connected to said trigger network, said trigger network including flip-flops for energizing pairs of control terminals in alternate states and amplifier means between said flip-flops and the respective control terminals.
Claim 4
Dependent Claim
61 words
The plasma-welding system defined in claim 2 wherein each flip-flop includes at least one bistable monovibrator having an input, means for producing a direct-current pulse train of a predetermined cadence of a bilateral switch interposed between the last mentioned means and said bistable monovibrator and conductive upon a voltage rise during each pulse of said train for activating the bistable monovibrator.
Claim 5
Dependent Claim
29 words
The plasma-welding system defined in claim 3 further comprising another bilateral switch movement connected to another input of said bistable monovibrator and triggerable in response to a supply frequency.
Claim 6
Dependent Claim
31 words
The plasma-welding system defined in claim 4, further comprising a transformer having a secondary winding connected to each of said inputs and a primary winding energized by the respective bilateral switch.
Claim 7
Dependent Claim
38 words
The plasma-welding system defined in claim 5 further comprising a rectifier diode connected in series with said other bistabile switch to a source of alternating current, and a capacitor connected between said diode and said other bistable switch.
Claim 8
Dependent Claim
34 words
The plasma-welding system defined in claim 1 wherein each of said devices is a transistor having its collector-emitter network forming the respective branch of said bridge, and a base connected to said trigger network.
Claim 9
Dependent Claim
23 words
The plasma-welding system defined in claim 7 further comprising a sintered-iron-core choke connected between said source and said bridge in said first diagonal.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-24 | 1977-06-25 | 1977-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-24 | 1981-06-25 | 1981-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-24 | 1985-06-25 | 1985-12-25 | $7700.00 | Window Closed / Lapsed |