US3825713A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Function control circuit for edm power supply
Assignee: Colt Industries Inc
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Filing: 1972-05-08
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Granted: 1974-07-23
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Expires: 1992-05-08
Abstract
Abstract A system for controlling an electrical discharge machining apparatus wherein the system is rendered responsive to an electrical gap parameter such as gap current or gap voltage level. Included in the system for responding to gap condition is a sensing circuit which includes a light-emissive device connected in circuit with the gap or with other essential operating elements such that there is provided a light output of an intensity proportional to gap current or voltage. A second, light responsive device such as a phototransistor or photo diode is used to convert the light signal into an electrical control signal, which signal in turn is utilized in a function control for the electrical discharge apparatus. The function control exercised includes machining power pulse on-time and off-time control, interruption of machining power responsive to gap short circuit condition, servo feed by providing relative movement of controllable speed and direction between a tool electrode and the workpiece, the gap width, and interruption of the power for the power supply in order to protect against gap short circuit condition arising from failure of an essential switching element in the EDM power supply such as one of the output electronic switches.
Inventors
- 👤 O Bell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:27
CPC Classifications
B; B23; B23H; B23H1/00; B23H1/02; B23H1/028; B23H1/022; B23H1/024; B23H7/00; B23H7/14; B23H7/18
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
151 words
In an electrical discharge machining apparatus for machining a conductive workpiece by an electrode tool across a dielectric coolant filled gap, a power source, a periodically operated electronic output switch operatively connected between said power source and the gap for providing machining power pulses thereto at frequencies ranging up to high frequencies, a pulse generator for controlling the on-time and the off-time of the machining power pulses, and a system for interrupting the operation of said switch responsive to gap short circuit condition, said system including a light-emitting device operatively connected to said gap for providing a light signal output which is a function of current passing through said gap, a light responsive means operatively connected to said device for providing a control electrical signal proportional to light signal magnitude, said light responsive means connected to the pulse generator for increasing the machining pulse off-time for the duration of said condition.
Claim 2
Dependent Claim
151 words
In an electrical discharge machining apparatus for machining a conductive workpiece by an electrode tool across a dielectric coolant filled gap, a power source, a periodically operated electronic output switch operatively connected between said power source and the gap for providing machining power pulses thereto at frequencies ranging up to high frequencies, a pulse generator for controlling the on-time and the off-time of the machining power pulses, and a system for interrupting the operation of said switch responsive to gap short circuit condition, said system including a light-emitting device operatively connected to said gap for providing a light signal output which is a function of current passing through said gap, a light responsive means operatively connected to said device for providing a control electrical signal proportional to light signal magnitude, said light responsive means connected to the pulse generator for increasing the machining pulse off-time for the duration of said condition.
Claim 3
Dependent Claim
55 words
The combination as set forth in claim 1 wherein said output switch is operated by an independent type pulse generator and wherein said light responsive means is operatively connected to said pulse generator for controlling its operation and accordingly the on-time and off-time operation of said output switch responsive gap current representative of said condition.
Claim 4
Dependent Claim
31 words
The combination as set forth in claim 1 wherein said light-emitting device comprises a light-emitting diode, said diode operably connected in series with the gap for responding to gap current level.
Claim 5
Dependent Claim
32 words
The combination as set forth in claim 3 wherein said diode is connected in series combination with a resistor, said combination connected across a second resistor coupled in series with the gap.
Claim 6
Dependent Claim
17 words
The combination as set forth in claim 1 wherein said light-emitting device comprises an incandescent light bulb.
Claim 7
Dependent Claim
31 words
The combination as set forth in claim 1 wherein said light-emitting device comprises a constant light source and a liquid crystal mounted intermediate said light source and said light responsive means.
Claim 8
Dependent Claim
173 words
In an electrical discharge machining apparatus for machining a conductive workpiece by an electrode tool across a dielectric coolant filled gap, a power source, a periodically operated electronic output switch operatively connected between said power source and the gap for providing machining power pulses thereto, and a system for controlling the operation of said output switch responsive to gap short circuit condition, said system including a light-emitting device operatively connected to said gap for providing a light signal outlight which is a function of current passing through said gap, a light responsive means operatively connected to said device for providing a control electrical signal proportional to light signal magnitude, said electronic output switch operated by a pulse generator comprising a multivibrator including a pair of alternately operated electronic switches, one controlling the on-time and the other controlling the off-time of the machining power pulses, said light responsive means operatively connected to and controlling said pulse on-time controlling switch of said multivibrator for decreasing the on-time responsive to increased current flow through said device.
Claim 9
Dependent Claim
173 words
In an electrical discharge machining apparatus for machining a conductive workpiece by an electrode tool across a dielectric coolant filled gap, a power source, a periodically operated electronic output switch operatively connected between said power source and the gap for providing machining power pulses thereto, and a system for controlling the operation of said output switch responsive to gap short circuit condition, said system including a light-emitting device operatively connected to said gap for providing a light signal outlight which is a function of current passing through said gap, a light responsive means operatively connected to said device for providing a control electrical signal proportional to light signal magnitude, said electronic output switch operated by a pulse generator comprising a multivibrator including a pair of alternately operated electronic switches, one controlling the on-time and the other controlling the off-time of the machining power pulses, said light responsive means operatively connected to and controlling said pulse on-time controlling switch of said multivibrator for decreasing the on-time responsive to increased current flow through said device.
Claim 10
Dependent Claim
186 words
In an electrical discharge machining apparatus for machining a conductive workpiece by an electrical tool across a dielectric coolant filled gap, a power source, a periodically operated electronic output switch operatively connected between said power source and the gap for providing machining power pulses thereto, an independent type pulse generator for operating said output switch, said pulse generator comprising a multivibrator including a pair of alternately operated electronic switches, one controlling the on-time and the other controlling the off-time of the machining power pulses, and a system for controlling the operation of said output switch responsive to gap short circuit condition, said system including a light-emitting device operatively connected to said gap for providing a light signal output which is a function of current passing through the gap, a light responsive means operatively connected to said device for providing a control electrical signal proportional to light signal magnitude, said light responsive means being connected to said pulse off-time control switch of said multivibrator for increasing the machining pulse off-time responsive to increased current flow through said device representative of impending short circuit condition of the gap.
Claim 11
Dependent Claim
186 words
In an electrical discharge machining apparatus for machining a conductive workpiece by an electrical tool across a dielectric coolant filled gap, a power source, a periodically operated electronic output switch operatively connected between said power source and the gap for providing machining power pulses thereto, an independent type pulse generator for operating said output switch, said pulse generator comprising a multivibrator including a pair of alternately operated electronic switches, one controlling the on-time and the other controlling the off-time of the machining power pulses, and a system for controlling the operation of said output switch responsive to gap short circuit condition, said system including a light-emitting device operatively connected to said gap for providing a light signal output which is a function of current passing through the gap, a light responsive means operatively connected to said device for providing a control electrical signal proportional to light signal magnitude, said light responsive means being connected to said pulse off-time control switch of said multivibrator for increasing the machining pulse off-time responsive to increased current flow through said device representative of impending short circuit condition of the gap.
Claim 12
Dependent Claim
171 words
In an electrical discharge machining apparatus for machining a conductive workpiece by an electrode tool across a dielectric coolant filled gap, a power source, a periodically operated electronic output switch operatively connected between the power source and the gap for providing machining power pulses thereto, said output switch operated by an independent type pulse generator, said pulse generator comprising an astable multivibrator of precisely controllable on-time and off-time and a system for controlling the operation of said output switch responsive to gap short circuit condition, said system including a light-emitting device operatively connected to said gap for providing a light signal output which is a function of current passing through the gap, a light responsive means operatively connected to said device for providing a control electrical signal proportional to light signal magnitude, said light responsive means operatively connected to said multivibrator for increasing the off-time and at the same time decreasing the on-time of the machining power pulses furnished to the gap for the duration of the gap short circuit condition.
Claim 13
Dependent Claim
171 words
In an electrical discharge machining apparatus for machining a conductive workpiece by an electrode tool across a dielectric coolant filled gap, a power source, a periodically operated electronic output switch operatively connected between the power source and the gap for providing machining power pulses thereto, said output switch operated by an independent type pulse generator, said pulse generator comprising an astable multivibrator of precisely controllable on-time and off-time and a system for controlling the operation of said output switch responsive to gap short circuit condition, said system including a light-emitting device operatively connected to said gap for providing a light signal output which is a function of current passing through the gap, a light responsive means operatively connected to said device for providing a control electrical signal proportional to light signal magnitude, said light responsive means operatively connected to said multivibrator for increasing the off-time and at the same time decreasing the on-time of the machining power pulses furnished to the gap for the duration of the gap short circuit condition.
Claim 14
Dependent Claim
137 words
In an electrical discharge machining apparatus for machining a conductive workpiece by providing machining power pulses thereto from an electrode tool across a dielectric coolant-filled gap, a power source and a periodically operated electronic output switch operatively connected to said power source and to the gap for providing machining pulses thereto, a protection system for interrupting said machining pulses responsive to failure of said output switch in a shorted condition comprising a resistor coupled in series with one of the principal electrodes of said output switch, a light-emitting device connected in parallel with said resistor and operable to provide a light output signal proportional to current flow therethrough of a magnitude sufficient to indicate output transistor failure, and a light responsive means linked to said device for providing an interruption of said machining pulses during said failure.
Claim 15
Dependent Claim
137 words
In an electrical discharge machining apparatus for machining a conductive workpiece by providing machining power pulses thereto from an electrode tool across a dielectric coolant-filled gap, a power source and a periodically operated electronic output switch operatively connected to said power source and to the gap for providing machining pulses thereto, a protection system for interrupting said machining pulses responsive to failure of said output switch in a shorted condition comprising a resistor coupled in series with one of the principal electrodes of said output switch, a light-emitting device connected in parallel with said resistor and operable to provide a light output signal proportional to current flow therethrough of a magnitude sufficient to indicate output transistor failure, and a light responsive means linked to said device for providing an interruption of said machining pulses during said failure.
Claim 16
Dependent Claim
58 words
The combination as set forth in claim 10 wherein said light responsive means comprises a phototransistor having its base operatively connected to said light-emitting device for providing an electrical control signal proportional to said light signal, wherein said phototransistor has its output operatively connected to said power source to provide disconnect of said source responsive to said condition.
Claim 17
Dependent Claim
25 words
The combination as set forth in claim 10 wherein said light-emitting device comprises a light-emitting diode phased to permit normal power flow to the gap.
Claim 18
Dependent Claim
18 words
The combination as set forth in claim 10 wherein said light-emitting device comprises an incandescent type light bulb.
Claim 19
Dependent Claim
31 words
The combination as set forth in claim 10 wherein said light-emitting device comprises a constant light source and a liquid crystal mounted between said light source and said light responsive means.
Claim 20
Dependent Claim
48 words
The combination as set forth in claim 11 wherein said power source has a relay operatively connected to it and controlling its connection to said gap, said electrical control signal operable to actuate said relay and to interrupt said power source connection during failure of said output transistor.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-22 | 1978-01-21 | 1978-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-22 | 1982-01-21 | 1982-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-22 | 1986-01-21 | 1986-07-23 | $7700.00 | Window Closed / Lapsed |