US3649802A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Protective system for electrical discharge machining power supply circuit
Assignee: Elox Inc
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Filing: 1970-12-28
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Granted: 1972-03-14
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Expires: 1990-12-28
Abstract
Abstract A circuit is provided to sense an electrical parameter of the gap to determine whether electrical discharge machining is progressing properly. A gap parameter such as gap voltage or a voltage directly related to such parameter is compared to a variable reference voltage to provide reduction or interruption of machining power pulses. A control is included which conjointly controls frequency of machining pulses and the magnitude of the variable reference voltage.
Inventors
- 👤 Kurt H Sennowitz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:41
CPC Classifications
B; B23; B23H; B23H1/00; B23H1/02; B23H1/024
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
168 words
In an electrical discharge machining apparatus for machining an electrically conductive workpiece by passing electrical discharges across a dielectric coolant filled gap between a tool electrode and the workpiece, an electronic output switch and a power supply operatively connected across said gap, a pulser means operatively connected to said switch for operating it with pulses of selectively variable on-off time and frequency, wherein the improvement comprises a circuit for reducing the power content of said pulses responsive to gap abnormal condition, said circuit comprising a variable reference voltage network, a sensing network operatively connected to said gap for sensing a parameter representative of gap condition and providing a voltage output representative thereof, a cutoff means operatively connected to both said networks and operable to reduce the ontime of said pulser responsive to a predetermined difference between said voltages, and means operatively connected between said pulser means and said reference voltage network for varying the magnitude of said reference voltage in response to the frequency preset on said pulser.
Claim 2
Dependent Claim
168 words
In an electrical discharge machining apparatus for machining an electrically conductive workpiece by passing electrical discharges across a dielectric coolant filled gap between a tool electrode and the workpiece, an electronic output switch and a power supply operatively connected across said gap, a pulser means operatively connected to said switch for operating it with pulses of selectively variable on-off time and frequency, wherein the improvement comprises a circuit for reducing the power content of said pulses responsive to gap abnormal condition, said circuit comprising a variable reference voltage network, a sensing network operatively connected to said gap for sensing a parameter representative of gap condition and providing a voltage output representative thereof, a cutoff means operatively connected to both said networks and operable to reduce the ontime of said pulser responsive to a predetermined difference between said voltages, and means operatively connected between said pulser means and said reference voltage network for varying the magnitude of said reference voltage in response to the frequency preset on said pulser.
Claim 3
Dependent Claim
169 words
In an electrical discharge machining apparatus for machining an electrically conductive workpiece by passing electrical discharges across a dielectric coolant filled gap between a tool electrode and the workpiece, an electronic output switch and a power supply operatively connected across said gap, a pulser means operatively connected to said switch for operating it with pulses of selectively variable on-off time and frequency, wherein the improvement comprises a circuit for reducing the power content of said pulses responsive to abnormal gap voltage condition, said circuit including a variable reference voltage network, a sensing network coupled to one terminal of said gap for sensing gap voltage and providing a voltage output representative thereof, a cutoff means operably connected to the output of both said networks and operative to reduce the on-time of said pulser responsive to the relative values of said voltages, and means operably connected between said pulser and said cutoff means for varying the magnitude of said reference voltage in accordance with the frequency setting of said pulser means.
Claim 4
Dependent Claim
169 words
In an electrical discharge machining apparatus for machining an electrically conductive workpiece by passing electrical discharges across a dielectric coolant filled gap between a tool electrode and the workpiece, an electronic output switch and a power supply operatively connected across said gap, a pulser means operatively connected to said switch for operating it with pulses of selectively variable on-off time and frequency, wherein the improvement comprises a circuit for reducing the power content of said pulses responsive to abnormal gap voltage condition, said circuit including a variable reference voltage network, a sensing network coupled to one terminal of said gap for sensing gap voltage and providing a voltage output representative thereof, a cutoff means operably connected to the output of both said networks and operative to reduce the on-time of said pulser responsive to the relative values of said voltages, and means operably connected between said pulser and said cutoff means for varying the magnitude of said reference voltage in accordance with the frequency setting of said pulser means.
Claim 5
Dependent Claim
162 words
In an electrical discharge machining apparatus for machining an electrically conductive workpiece by passing electrical discharges across a dielectric coolant filled gap between a tool electrode and the workpiece, an electronic output switch and a power operatively connected to said gap, a presettable multivibrator operatively connected to said electronic switch for operating it with pulses of selectively variable and on-off time frequency, wherein the improvement comprises a protective circuit for reducing the on-time of said pulses responsive to gap abnormal condition, said circuit comprising a variable reference voltage network, a sensing network coupled to one terminal of said gap for providing an output responsive to gap voltage condition, a cutoff switch operatively connected to both of said networks and having its output operatively connected to said multivibrator to reduce its on-time, and a control means operatively connected between said multivibrator and said reference voltage network for varying the level of said reference voltage network responsive to the frequency setting of said multivibrator.
Claim 6
Dependent Claim
162 words
In an electrical discharge machining apparatus for machining an electrically conductive workpiece by passing electrical discharges across a dielectric coolant filled gap between a tool electrode and the workpiece, an electronic output switch and a power operatively connected to said gap, a presettable multivibrator operatively connected to said electronic switch for operating it with pulses of selectively variable and on-off time frequency, wherein the improvement comprises a protective circuit for reducing the on-time of said pulses responsive to gap abnormal condition, said circuit comprising a variable reference voltage network, a sensing network coupled to one terminal of said gap for providing an output responsive to gap voltage condition, a cutoff switch operatively connected to both of said networks and having its output operatively connected to said multivibrator to reduce its on-time, and a control means operatively connected between said multivibrator and said reference voltage network for varying the level of said reference voltage network responsive to the frequency setting of said multivibrator.
Claim 7
Dependent Claim
47 words
The combination as set forth in claim 3 wherein said control means is operable to lower the level of said reference voltage at relatively low frequency settings of said multivibrator and to raise the level of said reference voltage at relatively high frequency settings of said multivibrator.
Claim 8
Dependent Claim
57 words
The combination as set forth in claim 3 wherein said multivibrator comprises an astable multivibrator including a variable capacitor operatively connected thereto for selectively varying the frequency of said multivibrator and wherein said reference voltage network includes a variable resistor, said control means comprising a ganged operating means operatively connected between said variable capacitor and said resistor.
Claim 9
Dependent Claim
69 words
The combination as set forth in claim 5 wherein said multivibrator includes a pair of transistors rendered alternately conductive and nonconductive and wherein said cutoff switch comprises a third transistor having its control electrode and one of its principal electrodes each connected to a different one Of said networks, and its other principal electrode coupled to the control electrode of one of said multivibrator transistors for controlling its conduction.
Claim 10
Dependent Claim
162 words
In an electrical discharge machining apparatus for machining an electrically conductive workpiece by passing electrical discharges across a dielectric coolant filled gap between a tool electrode and the workpiece, an electronic output switch and a power supply operatively connected to said gap, a presettable multivibrator operatively connected to said electronic switch for operating it with pulses of selectively variable frequency and on-off time, wherein the improvement comprises the protective circuit for reducing the on-time of said pulses responsive to gap short-circuit condition, said circuit comprising a variable reference voltage network, a sensing network coupled to said gap for providing an output responsive to gap voltage condition, a cutoff means operatively connected to both of said networks and having its output operatively connected to said multivibrator to reduce its on-time, and a control means operatively connected between said multivibrator and said reference voltage network for conjointly varying the level of said reference voltage network in accordance with the frequency setting of said multivibrator.
Claim 11
Dependent Claim
162 words
In an electrical discharge machining apparatus for machining an electrically conductive workpiece by passing electrical discharges across a dielectric coolant filled gap between a tool electrode and the workpiece, an electronic output switch and a power supply operatively connected to said gap, a presettable multivibrator operatively connected to said electronic switch for operating it with pulses of selectively variable frequency and on-off time, wherein the improvement comprises the protective circuit for reducing the on-time of said pulses responsive to gap short-circuit condition, said circuit comprising a variable reference voltage network, a sensing network coupled to said gap for providing an output responsive to gap voltage condition, a cutoff means operatively connected to both of said networks and having its output operatively connected to said multivibrator to reduce its on-time, and a control means operatively connected between said multivibrator and said reference voltage network for conjointly varying the level of said reference voltage network in accordance with the frequency setting of said multivibrator.
Claim 12
Dependent Claim
58 words
The combination as set forth in claim 7 wherein said control means is operable to lower the level of said reference voltage at relatively low frequency settings of said multivibrator and further operable to raise the level of said reference voltage at relatively high frequency settings of said multivibrator whereby changeover is made between rough and finishing operation.
Claim 13
Dependent Claim
57 words
The combination as set forth in claim 8 wherein said multivibrator comprises an astable multivibrator including a variable capacitor operatively connected thereto for selectively varying the frequency of said multivibrator and wherein said reference voltage network includes a variable resistor, said control means comprising a ganged operating means operatively connected between said variable capacitor and said resistor.
Claim 14
Dependent Claim
76 words
The combination as set forth in claim 9 wherein said multivibrator includes a pair of transistors rendered alternately conductive and nonconductive and wherein said cutoff switch comprises a third transistor having its control electrode and one of its principal electrodes each connected to different one of said networks and its other principal electrode coupled to the control electrode of one of said multivibrator transistors for controlling its conduction and thereby controlling the on-time of said pulses.
References Cited (Backward Citations)
US3158728A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-03-14 | 1975-09-13 | 1976-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-14 | 1979-09-13 | 1980-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-14 | 1983-09-13 | 1984-03-14 | $7700.00 | Window Closed / Lapsed |