US3777108A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Machining of workpieces by electro-erosion
Assignee: Individual
•
Filing: 1972-11-13
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Granted: 1973-12-04
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Expires: 1992-11-13
Abstract
Abstract The energizing circuit of an electro-erosion system, connected across an electrode and a workpiece to be machined, comprises a source of alternating current with an operating frequency of up to 5,000 Hz from which an unbroken succession of voltage pulses is obtained by means of a full-wave raw-rectification circuit. A reactance common to both branches of that circuit, such as an inductance effectively in series therewith, maintains a residual potential difference across the erosion gap as the driving voltage of the source goes to zero, resulting in continuing ionization of a substantially stationary dielectric liquid in the gap to increase the service life of the electrode by limiting the amplitude of the current pulses.
Inventors
- 👤 A Maillet
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:50
CPC Classifications
B; B23; B23H; B23H1/00; B23H1/02; B23H1/022; B23H2300/00; B23H2300/20
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
115 words
A system for machining a metallic workpiece by electroerosion, comprising: an electrode spaced by a gap from a surface of a workpiece to be machined; a body of ionizable dielectric liquid in said gap; and an energizing circuit including a source of contiguous unipolar voltage pulses with sloping flanks connected across said electrode and workpiece, said circuit further including reactance means for maintaining a residual potential difference across said gap at instants of zero source voltage to keep a degree of ionization in said liquid sufficient to initiate an intensified current flow through the gap on a rising flank of each voltage pulse at a level substantially below the breakdown potential of the de-ionized gap.
Claim 2
Independent Claim
115 words
A system for machining a metallic workpiece by electroerosion, comprising: an electrode spaced by a gap from a surface of a workpiece to be machined; a body of ionizable dielectric liquid in said gap; and an energizing circuit including a source of contiguous unipolar voltage pulses with sloping flanks connected across said electrode and workpiece, said circuit further including reactance means for maintaining a residual potential difference across said gap at instants of zero source voltage to keep a degree of ionization in said liquid sufficient to initiate an intensified current flow through the gap on a rising flank of each voltage pulse at a level substantially below the breakdown potential of the de-ionized gap.
Claim 3
Dependent Claim
35 words
A system as defined in claim 1 wherein said reactance means is dimensioned to maintain said residual potential difference for a period equal to at least one-tenth of a recurrence period of said voltage pulses.
Claim 4
Dependent Claim
19 words
A system as defined in claim 2 wherein said voltage pulses have a cadence not exceeding substantially 10 kHz.
Claim 5
Dependent Claim
38 words
A system as defined in claim 1 wherein said source comprises a transformer winding and a full-wave rectification network connected to opposite terminals of a secondary winding of said transformer, said winding forming part of said resistance means.
Claim 6
Dependent Claim
15 words
A system as defined in claim 1 wherein said reactance means comprises a series inductance.
Claim 7
Dependent Claim
40 words
A system as defined in claim 1, further comprising voltage-responsive servo means connected across said gap and coupled with said electrode and said workpiece for increasing the separation thereof in the presence of a negligible potential difference across said gap.
Claim 8
Dependent Claim
20 words
A system as defined in claim 1 wherein said electrode is perforated to provide at least one ascending venting channel.
Claim 9
Independent Claim
115 words
A method of machining a metallic workpiece by electro-erosion, comprising the steps of: positioning an electrode adjacent said workpiece with an intervening gap; disposing a body of an ionizable dielectric liquid in said gap; connecting said workpiece and said electrode across a source of contiguous unipolar voltage pulses with sloping flanks to generate a succession of current pulses Through said gap; and maintaining across said gap a residual potential difference at instants of zero source voltage to keep a degree of ionization in said liquid sufficient to initiate an intensified current flow through the gap on a rising flank of each voltage pulse at a level substantially below the breakdown potential of the de-ionized gap.
Claim 10
Independent Claim
115 words
A method of machining a metallic workpiece by electro-erosion, comprising the steps of: positioning an electrode adjacent said workpiece with an intervening gap; disposing a body of an ionizable dielectric liquid in said gap; connecting said workpiece and said electrode across a source of contiguous unipolar voltage pulses with sloping flanks to generate a succession of current pulses Through said gap; and maintaining across said gap a residual potential difference at instants of zero source voltage to keep a degree of ionization in said liquid sufficient to initiate an intensified current flow through the gap on a rising flank of each voltage pulse at a level substantially below the breakdown potential of the de-ionized gap.
Claim 11
Dependent Claim
19 words
A method as defined in claim 8 wherein said body of liquid is maintained substantially stationary between said pulses.
Claim 12
Dependent Claim
20 words
A method as defined in claim 8 wherein said pulses are generated at a cadence not exceeding substantially 10 kHz.
References Cited (Backward Citations)
US3056065A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-03 | 1977-06-04 | 1977-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-03 | 1981-06-04 | 1981-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-03 | 1985-06-04 | 1985-12-04 | $7700.00 | Window Closed / Lapsed |