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Improved Electro Discharge Machining

IP.com Disclosure Number: IPCOM000053008D
Original Publication Date: 1981-Aug-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Koblenz, MA: AUTHOR [+2]

Abstract

In Electro Discharge Machining (EDM), voltage pulses are applied at suitable intervals across two electrodes, where one of the electrodes is a workpiece. The electrodes are immersed in a liquid dielectric. When the voltage pulses are applied, the dielectric breaks down and discharge formations occur across the gap between the two electrodes. Materials are removed from the electrodes and craters are formed in them, where the crater size is proportional to the discharge energy. Roughness of the machine parts is reduced by reducing the crater size, which in turn is achieved by reducing the discharge energy. A capacitive discharge power supply system is described using a blocking capacitor and a diode serially connected with a resistor, the series diode-resistor connection being in parallel across the workpiece - tool electrodes.

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Improved Electro Discharge Machining

In Electro Discharge Machining (EDM), voltage pulses are applied at suitable intervals across two electrodes, where one of the electrodes is a workpiece. The electrodes are immersed in a liquid dielectric. When the voltage pulses are applied, the dielectric breaks down and discharge formations occur across the gap between the two electrodes. Materials are removed from the electrodes and craters are formed in them, where the crater size is proportional to the discharge energy. Roughness of the machine parts is reduced by reducing the crater size, which in turn is achieved by reducing the discharge energy. A capacitive discharge power supply system is described using a blocking capacitor and a diode serially connected with a resistor, the series diode-resistor connection being in parallel across the workpiece - tool electrodes.

Present capacitive discharge systems work well to reduce surface roughness as long as the capacitance is relatively high. However, as the capacitance is reduced to relatively low values, EDM operation becomes erratic. Additionally, since mechanical stresses are proportional to the discharge energy, it is difficult to machine highly miniaturized structures especially if a fragile material is to be machined. The circuit of Fig. 1 includes a pulse generator 10, a blocking capacitor 12, a diode 14, and a serially connected variable resistor 16. Capacitor 12 differentiates square wave pulses 18 supplied by the...