Research On Edm Pulse Generator For Machining Titanium Alloys

Titanium and titanium alloy have features of high strength weight ratio, good corrosion resistance, high calorific intensity, impact-resistant, which are widely used in various fields such as airplanes, missiles, ships, automobiles, oil, chemicals, biomedicine and so on. However, titanium alloy has disadvantages of lower thermal conductivity which cause bad performance in cutting process. For machining complex mold cavity of titanium alloy, electrical discharge machining (EDM) has a outstanding superiority. Pulse generator is one of the most important parts of electrical discharge machining machine tool and influences various process performance indicator. So it is significative to develop a new pulse generator which is suitable for the EDM of titanium alloy.On the basis of single factor experiments with traditional pulse generator, this paper analyzes scaling law of machining titanium alloy by EDM, which is ready for designing a pulse generator. The results indicate that there are dimples in the surface of work piece while there are bulges in the surface of electrode due to the serious discharge concentration. Therefore, this paper comes up with designing an asymmetrical pulse generator to machine titanium alloy efficiently and precisely by EDM, because the asymmetrical pulse may transfer and uniformize discharging points.The asymmetrical pulse generator is comprised of main oscillating circuit, driving circuit, power conversion circuit and detection circuit for discharging condition and so on. Based on MCU and CPLD, the pulse parameters can be set up between 5μs and 500μs by the main oscillating circuit. What's more, the main oscillating circuit can deal with discharging condition immediately. There are nine MOSFETS driving circuits, eight of which are parallel while the ninth can produce asymmetrical pulse.At last, circuit debugging and experiments contrasted with common pulse generator were carried out by using the unsymmetrical pulse generator. The experimental results show that machining efficiency of using the unsymmetrical pulse generator was higher than that of common pulse generator, and electrode wear ratio was reduced under the remaining conditions. So the new pulse generator is feasible for the machining of titanium alloy.