US3597570A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for detecting sustained arcing across electrospark machining gaps
Assignee: Mitsubishi Electric Corp
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Filing: 1969-05-22
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Granted: 1971-08-03
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Expires: 1989-05-22
Abstract
Abstract Each time a voltage across the machining gap due to each of applied pulses exceeds a predetermined above-arc magnitude, a timing capacitor is fully discharged by a shorting transistor triggered by a gap-coupled Zener diode. When the voltage is below the predetermined magnitude for a predetermined number of pulses, the capacitor is progressively charged until the voltage across the capacitor exceeds a predetermined magnitude and actuates an instrument for indicating that abnormal discharges are being effected across the gap.
Inventors
- 👤 Nagao Saito
- 👤 Kazuhiko Kobayashi
- 👤 Susumu Niwa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:01
CPC Classifications
B; B23; B23H; B23H1/00; B23H1/02; B23H1/024
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
144 words
A device for detecting the sustained arcing mode of operation of an electrical discharge machining apparatus having a machining gap formed between a machining electrode and a workpiece comprising: circuit means connected across the machining gap during use of the device for repeatedly providing an output signal only when the voltage across said gap is greater than the voltage occurring thereacross during arcing; a source of direct current; a capacitor connected across said source of direct current to be charged thereby; electric circuit means connected to said circuit means for repeatedly effecting discharge of said capacitor in response to said output signals and preventing discharge of said capacitor during the absence of an output signal; and detecting means for detecting when said capacitor has charged to a predetermined voltage level indicative of the sustained arcing mode of operation of the electrical discharge machining apparatus.
Claim 2
Independent Claim
144 words
A device for detecting the sustained arcing mode of operation of an electrical discharge machining apparatus having a machining gap formed between a machining electrode and a workpiece comprising: circuit means connected across the machining gap during use of the device for repeatedly providing an output signal only when the voltage across said gap is greater than the voltage occurring thereacross during arcing; a source of direct current; a capacitor connected across said source of direct current to be charged thereby; electric circuit means connected to said circuit means for repeatedly effecting discharge of said capacitor in response to said output signals and preventing discharge of said capacitor during the absence of an output signal; and detecting means for detecting when said capacitor has charged to a predetermined voltage level indicative of the sustained arcing mode of operation of the electrical discharge machining apparatus.
Claim 3
Dependent Claim
76 words
A device according to claim 1 wherein said circuit means includes a zener diode having a cathode electrode connected across said machining gap and having an anode electrode; and wherein said electric circuit means includes a transistor having base, collector and emitter electrodes, means connecting said base electrode to said anode electrode, and means connecting said base electrode to said anode electrode, and means connecting said collector and emitter electrodes to opposite sides of said capacitor.
Claim 4
Dependent Claim
17 words
A device according to claim 1 including means for variably setting the time constant of said capacitor.
Claim 5
Dependent Claim
34 words
A device according to claim 1 wherein said detecting means includes actuator means for changing the mode of operation of the electrical discharge machining apparatus in response to detection of said predetermined voltage level.
Claim 6
Independent Claim
185 words
A device for detecting the arcing or shorting mode of operation performed by an electrospark machining gap formed between a machining electrode and a workpiece, comprising: a source of direct current; a capacitor connected across said source of direct current and having a varying voltage thereacross increasing from substantially a null magnitude with a variably set time constant; circuit means including a transistor having base, collector and emitter electrodes and an emitter-to-collector circuit connected across said capacitor operative when conducting to discharge said capacitor and permit the latter to be again charged from substantially null magnitude when said time constant, and a Zener diode connected to said base electrode of said transistor responsive to the voltage applied across said machining gap to be conducting when a voltAge higher than the arc voltage appears across said machining gap whereupon said transistor is rendered conductive to discharge said capacitor; and actuator means responsive to the voltage across said capacitor having varied from said null magnitude to another predetermined magnitude indicative of said arcing or shorting mode of operation for changing the mode of operation of the machine.
Claim 7
Independent Claim
185 words
A device for detecting the arcing or shorting mode of operation performed by an electrospark machining gap formed between a machining electrode and a workpiece, comprising: a source of direct current; a capacitor connected across said source of direct current and having a varying voltage thereacross increasing from substantially a null magnitude with a variably set time constant; circuit means including a transistor having base, collector and emitter electrodes and an emitter-to-collector circuit connected across said capacitor operative when conducting to discharge said capacitor and permit the latter to be again charged from substantially null magnitude when said time constant, and a Zener diode connected to said base electrode of said transistor responsive to the voltage applied across said machining gap to be conducting when a voltAge higher than the arc voltage appears across said machining gap whereupon said transistor is rendered conductive to discharge said capacitor; and actuator means responsive to the voltage across said capacitor having varied from said null magnitude to another predetermined magnitude indicative of said arcing or shorting mode of operation for changing the mode of operation of the machine.
References Cited (Backward Citations)
US3483347A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-02 | 1975-02-01 | 1975-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-02 | 1979-02-01 | 1979-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-02 | 1983-02-01 | 1983-08-03 | $7700.00 | Window Closed / Lapsed |