Function control circuit for EDM power supply

Claim 2

In an electrical discharge machining apparatus for machining a conductive workpiece by passing machining power pulses from an electrode tool across a dielectric coolant-filled gap, a servo feed system for providing relative movement between said electrode tool and workpiece as material is removed, said servo feed system including reversible motive means, an electrically energized element operably connected to said motive means for controlling its operation responsive to current flow through said element, means for providing a signal output for said element comprising a light-emitting device connected in series with said gap and effective to provide A light output signal of an energy level magnitude representative of gap current level and hence of gap spacing, and a light responsive device operably linked to said light-emitting device for receiving and converting said light signal to an electrical signal for controlling said electrically energized element and said motive means.

Claim 3

The combination as set forth in claim 1 wherein said light-emitting device comprises a light-emitting diode, said diode connected in series combination with a resistor, said combination coupled in series with the gap.

Claim 4

The combination as set forth in claim 2 wherein said light responsive device comprises a phototransistor, said phototransistor having its base excited by said light signal and having one of its power electrodes operatively connected to said electrically energized element for controlling the operation of said motive means.

Claim 5

The combination as set forth in claim 1 wherein said motive means comprises a fluid operated motor and wherein said electrically energized element comprises a servo valve control coil operably associated with said motor for controlling its operation.

Claim 6

The combination as set forth in claim 1 wherein said light-emitting device comprises an incandescent type light bulb.

Claim 7

The combination as set forth in claim 1 wherein said light-emitting device comprises a liquid crystal device.

Claim 8

In an electrical discharge machining apparatus having a multiple gap set-up for providing electrical discharge machining between a plurality of electrodes and at least one workpiece at the same time, a servo feed system for controlling the operation of all of the individual electrodes comprising a common support for said electrodes, a reversible motive means connected to said support for advancing and retracting all the electrodes at the same time, an electrically energized element operatively connected to and controlling the operation of said motive means responsive to current flow therethrough, a separate sensing lead connected in series with each of said gaps, each of said leads coupled to the control electrode of a different electronic switch, each of said switches having a corresponding principal electrode connected in common, each of said electronic switches further having corresponding principal electrodes coupled to the control electrode of a control electronic switch, said control electronic switch having its output operatively connected to and controlling current flow through said electrically energized element for controlling the operation of said motive means.

Claim 9

In an electrical discharge machining apparatus having a multiple gap set-up for providing electrical discharge machining between a plurality of electrodes and at least one workpiece at the same time, a servo feed system for controlling the operation of all of the individual electrodes comprising a common support for said electrodes, a reversible motive means connected to said support for advancing and retracting all the electrodes at the same time, an electrically energized element operatively connected to and controlling the operation of said motive means responsive to current flow therethrough, a separate sensing lead connected in series with each of said gaps, each of said leads coupled to the control electrode of a different electronic switch, each of said switches having a corresponding principal electrode connected in common, each of said electronic switches further having corresponding principal electrodes coupled to the control electrode of a control electronic switch, said control electronic switch having its output operatively connected to and controlling current flow through said electrically energized element for controlling the operation of said motive means.

Claim 10

The combination as set forth in claim 7 wherein the output of said control switch is coupled to one terminal of said electrically energized element and wherein a selectively adjustable reference voltage is connected to its other terminal.

Claim 11

The combination as set forth in claim 7 wherein said electronic switches comprise a PNP transistor having its respective input lead diode coupled to its base and wherein all of the emitters of said electronic control switches are coupled in common to the control electrode of said control switch.

Claim 12

The combination as set forth in claim 7 wherein said motive means is of the fluid-operated type and wherein said electrically energized element comprises a servo valve control coil for controlling the movement of said motive means.

Claim 13

The combination as set forth in claim 7 wherein a light-emitting device is operatively connected in series with each of said gaps for providing a light output signal representative of gap current level and hence of gap spacing, and wherein said sensing leads each include a light responsive device for changing said light signal into an electrical control signal.

Claim 14

In an electrical discharge machining apparatus having a multiple gap setup providing electrical discharge machining between a plurality of electrodes and at least one workpiece at the same time, a servo feed system for controlling the operation of all such electrodes comprising a common suppOrt for said electrodes; a reversible motive means connected to said support for advancing and retracting all the electrodes at the same time; an electrically energized element operatively connected to and controlling the operation of said motive means responsive to current flow therethrough; a sensing circuit connected in series with each of the gaps, each such sensing circuit including a light emitting device for providing a light output signal representative of gap current level and hence of gap spacing; a plurality of light responsive devices each operatively connected to and controlled by a different one of said light emitting devices for changing said light signal into an electrical control signal, the output of each of said light responsive devices coupled to the control electrode of a different electronic switch; each of said switches having a corresponding principal electrode connected in common; each of said electronic switches further having corresponding principal electrodes coupled to the control electrode of a control electronic switch, said control electronic switch having its output operatively connected to and controlling current flow through said element.

Claim 15

In an electrical discharge machining apparatus having a multiple gap setup providing electrical discharge machining between a plurality of electrodes and at least one workpiece at the same time, a servo feed system for controlling the operation of all such electrodes comprising a common suppOrt for said electrodes; a reversible motive means connected to said support for advancing and retracting all the electrodes at the same time; an electrically energized element operatively connected to and controlling the operation of said motive means responsive to current flow therethrough; a sensing circuit connected in series with each of the gaps, each such sensing circuit including a light emitting device for providing a light output signal representative of gap current level and hence of gap spacing; a plurality of light responsive devices each operatively connected to and controlled by a different one of said light emitting devices for changing said light signal into an electrical control signal, the output of each of said light responsive devices coupled to the control electrode of a different electronic switch; each of said switches having a corresponding principal electrode connected in common; each of said electronic switches further having corresponding principal electrodes coupled to the control electrode of a control electronic switch, said control electronic switch having its output operatively connected to and controlling current flow through said element.

Claim 16

The combination as set forth in claim 12 wherein the output of said control electronic switch is coupled to one terminal of said electrically energized element, and wherein a selectively adjustable reference voltage is connected to its other terminal.

Claim 17

The combination as set forth in claim 12 wherein said light emitting device comprises an incandescent light bulb.

Claim 18

The combination as set forth in claim 12 wherein said light emitting device comprises a light emitting diode.

Claim 19

The combination as set forth in claim 12 wherein said light emitting device includes a liquid crystal.

Claim 20

In an electrical discharge machining apparatus having a multiple gap setup providing electrical discharge machining between a plurality of electrodes and at least one workpiece at the same time, a servo feed system for controlling the operation of all such electrodes comprising a common support for said electrodes; a reversible motive means connected to said support for advancing and retracting all the electrodes at the same time; an electrically energized element operatively connected to and controlling the operation of said motive means; a sensing circuit connected in series with each of the gaps, each such sensing circuit including a light emitting device for providing a light output signal representative of gap current level and hence of gap spacing; a plurality of light responsive devices each operatively connected to and controlled by a different one of said light emitting devices for changing said light signal into an electrical control signal, the output of each of said light responsive devices coupled to a like terminal of said electrically energized element for controlling the operation of said motive means.

Claim 21

In an electrical discharge machining apparatus having a multiple gap setup providing electrical discharge machining between a plurality of electrodes and at least one workpiece at the same time, a servo feed system for controlling the operation of all such electrodes comprising a common support for said electrodes; a reversible motive means connected to said support for advancing and retracting all the electrodes at the same time; an electrically energized element operatively connected to and controlling the operation of said motive means; a sensing circuit connected in series with each of the gaps, each such sensing circuit including a light emitting device for providing a light output signal representative of gap current level and hence of gap spacing; a plurality of light responsive devices each operatively connected to and controlled by a different one of said light emitting devices for changing said light signal into an electrical control signal, the output of each of said light responsive devices coupled to a like terminal of said electrically energized element for controlling the operation of said motive means.

Claim 22

The combination as set forth in claim 17 wherein said light emitting device comprises an incandescent light bulb.

Claim 23

The combination as set forth in claim 17 wherein said light emitting device comprises a light emitting diode.

Claim 24

The combination as set forth in claim 17 wherein said light emitting device includes a liquid crystal.