US3778579A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arc control
Assignee: Amsted Industries Inc
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Filing: 1972-04-27
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Granted: 1973-12-11
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Expires: 1992-04-27
Abstract
Abstract A toroid senses the time rate of change of current at the gap between an electrode and a workpiece in an electrical discharge machining apparatus. An abnormal time rate of change of current causes a signal to be developed by a Schmitt trigger, which causes interruption of power flow to the gap.
Inventors
- 👤 E Takarada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 05:51
CPC Classifications
B; B23; B23H; B23H1/00; B23H1/02; B23H1/024
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
105 words
In an electrical discharge machining assembly including pulse-generating means for supplying pulses of a predetermined frequency and duty cycle, an electrode and a conductive workpiece defining therebetween an ionizable gap, and a circuit coupling said pulse-generating means with said electrode and workpiece whereby discrete discharges are passed through said gap to machine said workpiece, the improvement comprising means coupled with said circuit for detecting the time rate of change of current at said gap, and means coupled with said detecting means for interrupting said discrete discharges in response to detection of the time rate of change of current at said gap above a preselected value.
Claim 2
Dependent Claim
105 words
In an electrical discharge machining assembly including pulse-generating means for supplying pulses of a predetermined frequency and duty cycle, an electrode and a conductive workpiece defining therebetween an ionizable gap, and a circuit coupling said pulse-generating means with said electrode and workpiece whereby discrete discharges are passed through said gap to machine said workpiece, the improvement comprising means coupled with said circuit for detecting the time rate of change of current at said gap, and means coupled with said detecting means for interrupting said discrete discharges in response to detection of the time rate of change of current at said gap above a preselected value.
Claim 3
Dependent Claim
64 words
The invention according to claim 1, said detecting means including a toroid inducing a signal current in response to detection of the time rate of change of current at said gap, said interrupting means including means for supplying a signal in response to induced signal current above a preselected value and means responsive to the presence of said signal for interrupting said discrete discharges.
Claim 4
Dependent Claim
174 words
In an electrical discharge machining assembly, the combination comprising a pulse-generator, an electrode and a conductive workpiece defining therebetween an ionizable gap, and a circuit coupling said pulse-generator with said electrode and workpiece whereby discrete discharges are passed through said gap to machine said workpiece, said circuit including an invertor coupled with said pulse-generator for inverting its voltage pulses, means for differentiating the inverted pulses, a flip-flop having its reset responsive to the inverted and differentiated pulses, an AND gate having inputs coupled with said pulse-generator and said flip-flop and having an output coupled with said electrode, toroid means for sensing the time rate of change of current at said gap, and a Schmitt trigger actuated by said toroid to produce a signal representative of the time rate of change of current at said gap above a predetermined level, said flip-flop having its set responsive to the signal, whereby a time rate of change of current at said gap above the predetermined level causes the flip-flop to interrupt the pulses beyond said AND gate.
Claim 5
Dependent Claim
174 words
In an electrical discharge machining assembly, the combination comprising a pulse-generator, an electrode and a conductive workpiece defining therebetween an ionizable gap, and a circuit coupling said pulse-generator with said electrode and workpiece whereby discrete discharges are passed through said gap to machine said workpiece, said circuit including an invertor coupled with said pulse-generator for inverting its voltage pulses, means for differentiating the inverted pulses, a flip-flop having its reset responsive to the inverted and differentiated pulses, an AND gate having inputs coupled with said pulse-generator and said flip-flop and having an output coupled with said electrode, toroid means for sensing the time rate of change of current at said gap, and a Schmitt trigger actuated by said toroid to produce a signal representative of the time rate of change of current at said gap above a predetermined level, said flip-flop having its set responsive to the signal, whereby a time rate of change of current at said gap above the predetermined level causes the flip-flop to interrupt the pulses beyond said AND gate.
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) | 1976-12-10 | 1977-06-11 | 1977-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-10 | 1981-06-11 | 1981-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-10 | 1985-06-11 | 1985-12-11 | $7700.00 | Window Closed / Lapsed |