Patent US4617443A successfully refreshed from Google Patents.
US4617443A
Expired / Lapsed
US
⏱️ 0.0 years remaining
EDM apparatus pulse generator
Assignee: Agie Charmilles New Technologies SA
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Filing: 1985-03-25
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Granted: 1986-10-14
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Expires: 2005-03-25
Abstract
Abstract An apparatus and method for improving the surface finish of a workpiece machined by an EDM apparatus having an electrode tool mounted in a tool holder insulated from the rest of the apparatus structure, the EDM apparatus comprising a pulse generator applying electrical discharges across the electrode tool and the workpiece, and wherein a parasitical capacitor is formed by the tool holder insulated from the rest of the apparatus. The parasitical capacitor, connected across the pulse generator output, is charged and discharged during operation of the pulse generator, and the discharge energy of the parasitical capacitor is added to the energy of the electrical discharge supplied by the pulse generator. For the purpose of obtaining a smooth surface finish on the workpiece with decreased energy of the machining electrical pulses, a compensating inductance is placed in series in the discharge circuit. The compensating inductance preferably takes the form of a high permeability magnetic circuit disposed around a portion of the discharge circuit, for example around a portion of the electrode tool shank mounting the electrode tool in the tool holder.
Inventors
- 👤 Roland Martin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:45
CPC Classifications
B; B23; B23H; B23H7/00; B23H7/38
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
252 words
In an EDM apparatus wherein a workpiece is machined by electro-erosive electrical discharges by means of an electrode tool, said apparatus comprising an electrical pulse generator connected across the workpiece and the electrode tool by electrical conductors for applying voltage pulses of predetermined waveform across a machining zone between the electrode tool and the workpiece for causing machining electrical dischargess across said machining zone, wherein said apparatus comprises a frame structure, a machining head mounted on said frame structure, an electrode tool holder mounted on said machining head, said electrode tool being attached to said tool holder and said electrode tool holder being electrically insulated from said machining head whereby a parasitical capacitance is formed between said electrode tool holder and said machining head, said pulse generator, electrical conductors, workpiece, machining zone and electrode tool defining a workpiece machining circuit, and said parasitical capacitance being charged by said voltage pulses applied across said machining zone prior to said electrical discharges occurring across said machining zone and discharged through a circuit disposed in parallel with said machining circuit and comprising said apparatus frame structure, said machining head, said electrode tool holder, said electrode tool, said machining zone and said workpiece, an improvement comprising an inductance inserted anywhere in the charge and discharge parallel circuit of said parasitical capacitance which comprises said apparatus frame structure, said machining head, said electrode tool holder, said electrode tool, said machining zone and said workpiece only during finish machining of said workpiece by electrical discharges of low energy.
Claim 2
Dependent Claim
252 words
In an EDM apparatus wherein a workpiece is machined by electro-erosive electrical discharges by means of an electrode tool, said apparatus comprising an electrical pulse generator connected across the workpiece and the electrode tool by electrical conductors for applying voltage pulses of predetermined waveform across a machining zone between the electrode tool and the workpiece for causing machining electrical dischargess across said machining zone, wherein said apparatus comprises a frame structure, a machining head mounted on said frame structure, an electrode tool holder mounted on said machining head, said electrode tool being attached to said tool holder and said electrode tool holder being electrically insulated from said machining head whereby a parasitical capacitance is formed between said electrode tool holder and said machining head, said pulse generator, electrical conductors, workpiece, machining zone and electrode tool defining a workpiece machining circuit, and said parasitical capacitance being charged by said voltage pulses applied across said machining zone prior to said electrical discharges occurring across said machining zone and discharged through a circuit disposed in parallel with said machining circuit and comprising said apparatus frame structure, said machining head, said electrode tool holder, said electrode tool, said machining zone and said workpiece, an improvement comprising an inductance inserted anywhere in the charge and discharge parallel circuit of said parasitical capacitance which comprises said apparatus frame structure, said machining head, said electrode tool holder, said electrode tool, said machining zone and said workpiece only during finish machining of said workpiece by electrical discharges of low energy.
Claim 3
Dependent Claim
25 words
The improvement of claim 1 wherein said inductance takes the form of a highly permeable magnetic circuit disposed surrounding a portion of said parallel circuit.
Claim 4
Dependent Claim
22 words
The improvement of claim 2 wherein said portion of said parallel circuit is between said electrode tool holder and said electrode tool.
Claim 5
Dependent Claim
11 words
The improvement of claim 1 wherein said inductance is variably adjustable.
Claim 6
Dependent Claim
15 words
The improvement of claim 4 further comprising a control circuit for controllably varying said inductance.
Claim 7
Independent Claim
237 words
A method for improving surface finish on a workpiece machined by an electrode tool in an EDM apparatus comprising an electrical pulse generator connected across the workpiece and the electrode tool by electrical conductors for applying voltage pulses of predetermined waveform across a machining zone between the electrode tool and the workpiece for causing machining electrical discharges across said machining zone, said pulse generator, electrical conductors, workpiece, machining zone and electrode tool defining a workpiece machining circuit, and wherein said apparatus comprises a frame structure, a machining head mounted on said frame structure, and an electrode tool holder supporting said electrode tool mounted on said machining head, said electrode tool holder being electrically insulated from said machining head whereby a parasitical capacitance is formed between said electrode tool holder and said machining head, said parasitical capacitance being charged by said voltage pulses applied across said machining zone prior to said electrical discharges occurring across said machining zone and discharged through a parallel circuit comprising said apparatus frame structure, said machining head, said electrode tool holder, said electrode tool, said machining zone and said workpiece, said method comprising inserting an inductance anywhere in the parallel charge and discharge circuit of said parasitical capacitance which comprises said apparatus frame structure, said machining head, said electrode tool holder, said electrode tool, and machining zone and said workpiece only during finish machining of said workpiece by electrical discharges of low energy.
Claim 8
Independent Claim
237 words
A method for improving surface finish on a workpiece machined by an electrode tool in an EDM apparatus comprising an electrical pulse generator connected across the workpiece and the electrode tool by electrical conductors for applying voltage pulses of predetermined waveform across a machining zone between the electrode tool and the workpiece for causing machining electrical discharges across said machining zone, said pulse generator, electrical conductors, workpiece, machining zone and electrode tool defining a workpiece machining circuit, and wherein said apparatus comprises a frame structure, a machining head mounted on said frame structure, and an electrode tool holder supporting said electrode tool mounted on said machining head, said electrode tool holder being electrically insulated from said machining head whereby a parasitical capacitance is formed between said electrode tool holder and said machining head, said parasitical capacitance being charged by said voltage pulses applied across said machining zone prior to said electrical discharges occurring across said machining zone and discharged through a parallel circuit comprising said apparatus frame structure, said machining head, said electrode tool holder, said electrode tool, said machining zone and said workpiece, said method comprising inserting an inductance anywhere in the parallel charge and discharge circuit of said parasitical capacitance which comprises said apparatus frame structure, said machining head, said electrode tool holder, said electrode tool, and machining zone and said workpiece only during finish machining of said workpiece by electrical discharges of low energy.
Claim 9
Dependent Claim
25 words
The method of claim 6 wherein said inductance takes the form of a high permeability magnetic circuit disposed surrounding a portion of said parallel circuit.
Claim 10
Dependent Claim
21 words
The method of claim 7 wherein said portion of parallel circuit is between said electrode tool holder and said electrode tool.
Claim 11
Dependent Claim
18 words
The method of claim 6 further comprising adjustably varying said inductance as a function of desired surface finish.
Claim 12
Dependent Claim
18 words
The method of claim 7 further comprising adjustably varying said inductance as a function of desired surface finish.
Claim 13
Dependent Claim
18 words
The method of claim 8 further comprising adjustably varying said inductance as a function of desired surface finish.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-10-13 | 1990-04-14 | 1990-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-13 | 1994-04-14 | 1994-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-13 | 1998-04-14 | 1998-10-14 | $7700.00 | Window Closed / Lapsed |