The Key Technology Research On Cool Electrode Of Electrical Discharge Machining Of Titanium Alloy

Titanium alloy is a kind of difficult to machining metal materials with outstanding characteristic, which has been widely used in the industry and daily life, so the convenient and efficient machining method of titanium alloy has drawn many researchers’ attention. Electrical discharge machining(EDM) is a kind of non-traditional machining process without cutting force, which is very suitable for machining titanium alloy. However, the thermal conductivity of the titanium alloy is very low, which damaged the stability of machining titanium alloy with EDM and the tool electrode wear is high, especially in the finishing machining period. To improve the EDM stability of titanium alloy and reduce the electrode wear, this paper proposed the cool electrode EDM process which can strengthen the heat dissipation capacity of tool electrode through asymmetric heat dissipation method. Due to the improvement of the heat dissipation capacity of tool electrode, the cooling statement between the electrode and the workpiece was enhanced and the deionization statement of the discharge channel was improved, which reduced the electrode wear and improved the stability of machining titanium alloy with EDM. Specific works are as follows:(1) A specially used cool electrode in this paper was designed based on the peltier effect of semiconductor PN junctions and a monopulse discharge detection and control system based on the current detection method was designed, which laid a good foundation for studying the characteristics of machining titanium alloy with cool electrode EDM.(2) The voltage waveform and current waveform of cool electrode and conventional electrode during the discharge progress was analysed, respectively. The result show that the initial maintain voltage of cool electrode was lower than that of conventional electrode, and there is a obvious heat compensation period of discharge channel when machining titanium alloy with cool electrode. The model of discharge channel of cool electrode was established due to the experiment result.(3) Besides, monopulse discharge experiment of machining titanium alloy with cool electrode and conventional electrode under the same test conditions was carried out, the influence of the temperature of the tool electrode on the discharge gap and corrosion resistance coefficient of tool electrode was analyzed in this paper. Temperature field distribution between the tool electrode and the workpiece was simulated by ANSYS software, the result confirmed the low electrode wear characteristic of cool electrode from the theory angle.(4) A comparative experiment of corner size machining accuracy by cool electrode and conventional electrode was carried out and the result show that the discharge gap declines with the decrease of the temperature of tool electrode, which can improve the machining accuracy of corner size. The surface of workpiece machined by cool electrode and conventional electrode was studied in this paper.(5) Proceeded technological tests of titanium alloy forming with cool electrode and studied the relationship between the electrode temperature, machining polarity, electrical parameter, dielectric fluid and the MRR, EWR.