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Patent US3999028A successfully refreshed from Google Patents.
US3999028A
Expired / Lapsed
US
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Method and apparatus for electrical discharge machining
Assignee: Mitsubishi Electric Corp
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Filing: 1973-12-19
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Granted: 1976-12-21
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Expires: 1993-12-19
Abstract
Abstract A method and apparatus for shaping a workpiece by electrical discharge, the workpiece being shaped by a shaping electrode by intermittently impressing a voltage pulse across a working gap formed between the workpiece and the shaping electrode. The apparatus comprises a means for efficiently controlling the duration of a discharge across the working gap according to a condition dependent upon a no-load voltage impressing period, i.e., the period of operation beginning with the impression of the voltage pulse and ending with the occurrence of a discharge, and further according to the state of the working gap detected in terms of a processing voltage mean value. When a no-load voltage impressing period is inside a given interval, the duration of a discharge is increased according to the length of the period. Alternatively, when the no-load voltage impressing period is outside the given interval, the duration of a discharge corresponding to the state of the working gap is not increased. Accordingly, operating stability is improved and electrode consumption is minimized.
Inventors
- 👤 Nagao Saito
- 👤 Kazuhiko Kobayashi
- 👤 Toshiro Oizumi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 21:32
CPC Classifications
B; B23; B23H; B23H1/00; B23H1/02; B23H1/022
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
129 words
A method of shaping a workpiece by electrical discharge, comprising the steps of: intermittently impressing a voltage pulse across a working gap formed between a workpiece and an electrode to generate a discharge during a discharge period; detecting the no-load period between the instant at which the voltage pulse is impressed across the working gap and the instant at which a discharge occurs between the workpiece and the electrode; detecting the average processing voltage across the working gap; and varying the discharge period in accordance with the detected no-load period and in accordance with the detected average processing voltage to cause the discharge period to vary directly as the no-load period and to vary inversely as the average processing voltage after the average processing voltage reaches a predetermined level.
Claim 2
Independent Claim
129 words
A method of shaping a workpiece by electrical discharge, comprising the steps of: intermittently impressing a voltage pulse across a working gap formed between a workpiece and an electrode to generate a discharge during a discharge period; detecting the no-load period between the instant at which the voltage pulse is impressed across the working gap and the instant at which a discharge occurs between the workpiece and the electrode; detecting the average processing voltage across the working gap; and varying the discharge period in accordance with the detected no-load period and in accordance with the detected average processing voltage to cause the discharge period to vary directly as the no-load period and to vary inversely as the average processing voltage after the average processing voltage reaches a predetermined level.
Claim 3
Dependent Claim
133 words
Apparatus for shaping a workpiece by electrical discharge comprising: means for intermittently impressing a voltage pulse across a working gap formed between a workpiece and an electrode to generate a discharge during a discharge period; means for detecting the no-load period between the instant at which the voltage pulse is impressed across the working gap and the instant at which a discharge occurs between the workpiece and the electrode; means for detecting the average processing voltage across the working gap; and means for varying the discharge period in accordance with the detected no-load period and in accordance with the detected average processing voltage to cause the discharge period to vary directly as the no-load period and to vary inversely as the average processing voltage after the average processing voltage reaches a predetermined level.
Claim 4
Dependent Claim
133 words
Apparatus for shaping a workpiece by electrical discharge comprising: means for intermittently impressing a voltage pulse across a working gap formed between a workpiece and an electrode to generate a discharge during a discharge period; means for detecting the no-load period between the instant at which the voltage pulse is impressed across the working gap and the instant at which a discharge occurs between the workpiece and the electrode; means for detecting the average processing voltage across the working gap; and means for varying the discharge period in accordance with the detected no-load period and in accordance with the detected average processing voltage to cause the discharge period to vary directly as the no-load period and to vary inversely as the average processing voltage after the average processing voltage reaches a predetermined level.
Claim 5
Dependent Claim
35 words
Apparatus for shaping a workpiece by electrical discharge in accordance with claim 2 wherein the means for intermittently impressing a voltage pulse comprises a plurality of switching transistors connected between the workpiece and the electrode.
Claim 6
Dependent Claim
40 words
Apparatus for shaping a workpiece by electrical discharge in accordance with claim 2 further comprising a monostable multivibrator for controlling the length of the quiescent period between the termination of the discharge period and the initiation of the no-load period.
Claim 7
Dependent Claim
45 words
Apparatus for shaping a workpiece by electrical discharge in accordance with claim 2 wherein the means for varying the discharge period in accordance with the detected no-load period and in accordance with the detected average processing voltage comprises a circuit having a predetermined time constant.
References Cited (Backward Citations)
US3590317A
Cited
US3614368A
Cited
US3614368B1
Cited
US3705287A
Cited
US3697719A
Cited
US3755645A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-12-21 | 1980-06-21 | 1980-12-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-12-21 | 1984-06-21 | 1984-12-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-12-21 | 1988-06-21 | 1988-12-21 | $7700.00 | Window Closed / Lapsed |