Servomechanism feed system

Claim 2

A servomechanism feed system comprising, in combination: a source of electrical power; a first movable means; input signal means operatively connected to said first movable means for providing an electrical input signal representative of a condition in the vicinity of said first movable means; motive means operatively connected to said first movable means for selectively moving said first movable means; an electrically energized element operatively connected to and controlling the operation of said motive means; velocity control means operatively connected to and controlling the operation of said electrically energized element; variable reference signal means operatively connected between said source of electrical power and said velocity control means for providing a variable reference signal; and electrical means operatively connected to said input signal means, to said velocity control means, and to said variable reference signal means for providing a back-up signal for saiD electrically energized element only after a high velocity overshoot of said variable reference signal.

Claim 3

The combination according to claim 1 for use in an electrical discharge machining apparatus, wherein: said first movable means is a tool electrode in said electrical discharge machining apparatus; said input signal means is operatively connected to said electrode tool for providing an electrical input signal representative of arc gap voltage between said electrode tool and the conductive workpiece being operated on by said electrical discharge machining apparatus; said velocity control means includes a variable potentiometer; and said variable reference signal means includes a variable potentiometer.

Claim 4

The combination according to claim 1, including a pair of complementary first and second electronic control devices each of which has a control electrode and two power electrodes, the control electrodes of said electronic control devices being connected together, and one power electrode of each of said electronic control devices being connected to a common terminal of said electrically energized element and said velocity control means.

Claim 5

The combination according to claim 3, wherein said electrical means includes a third electronic control device having a control electrode and two power electrodes; first impedance means connected between one terminal of said input signal means and said control electrode of said third electronic control device; second impedance means connected between said variable reference signal means and one of said power electrodes of said third electronic control device; the other terminal of said input signal means being connected to one terminal of said source of electric power; a first parallel resistance-capacitance network having one of its terminals connected to said one terminal of said source of electrical power; a first electrical component connected between said other power electrode of said third electronic control device and the other terminal of said first parallel resistance-capacitance network; said electrical component having a substantially low impedance to the flow of electrons in a predetermined direction and having a substantially high impedance to the flow of electrons in a direction opposite to said predetermined direction.

Claim 6

The combination according to claim 4, wherein said electrical means includes a fourth electronic control device having a control electrode two power electrodes and a network connected between the control electrode of said fourth electronic control device and the control electrode of said pair of complementary first and second electronic control devices; said variable reference signal means including a variable potentiometer; and one of the power electrodes of said fourth electronic control device being connected to the movable element of said variable potentiometer of said variable reference signal means.

Claim 7

The combination according to claim 5, wherein said network connected between the control electrode of the fourth electronic control device and the control electrode of the first and second electronic control devices includes: a series arrangement of a resistor and a capacitor connected between said other terminal of said first parallel resistance-capacitance network and the control electrode of said pair of complementary first and second electronic control devices; and a series arrangement of a resistor and a diode connected between said other terminal of said first parallel resistance-capacitance network and said control electrode of said fourth electronic control device.

Claim 8

The combination according to claim 1, wherein: said electrically energized element comprises a coil; said velocity control means includes a variable potentiometer and a first resistor which is connected between the movable element of said variable potentiometer and one terminal of said coil; said other terminal of said Coil being connected to a terminal of said variable potentiometer.

Claim 9

The combination according to claim 7, including: a second parallel resistance-capacitance network having one of its terminals connected to said one terminal of said source of electrical power; the other terminal of said second parallel resistance-capacitance network being operatively connected to said terminal of said variable potentiometer of said velocity control means; The other terminal of said variable potentiometer of said vlocity control means being connected to a parallel network including a resistor, a diode and a capacitor; third impedance means operatively connected between the other terminal of said last-mentioned parallel network and said other terminal of said first parallel resistance-capacitance network.

Claim 10

The combination according to claim 8, including: a pair of complementary diodes connected between said other terminal of said last-mentioned parallel network and the other power electrode of said pair of complementary first and second electronic control devices, respectively.

Claim 11

The combination according to claim 1, wherein said electrical means includes first and second electronic control devices each of which has a control electrode and two power electrodes, the control electrodes of said electronic control devices being connected together, and impedance means connected between said control electrodes and said electrically energized element, said impedance means providing a transient response in output voltage signal applied to said electrically energized element.