Basic Process Research On Electrical Discharge Machining With Ultrasonic Vibration Of Dielectric Fluid

The polymer microfluidic chip is widely applied in biomedical medical and other fields.Hot embossing and injection molding are the main technological methods and the fabrication of microscale structure is the key to mould manufacturing.In addition to LIGA,UV-LIGA,to adopt EDM can fabricate microscale structure in die steel with high hardness,which can reduce the cost of mould fabrication process,as well as extend serving life of the mould.By far,microscale structure produced by EDM basically has met the requirements of practical usage.But there still exists some problems of surface quality caused by abnormal discharge of electrical machine.Therefore,it is significant to develop a method to improve the quality of microscale structure manufactured by conventional EDM.Hence,in order to improve the quality of mold surface,based on the current way of ultrasonic vibration that assisted to electrical discharge machining,this paper proposes a new method of ultrasonic vibration applying to dielectric liquid in EDM.Ultrasonic vibration box is completely submerged in the dielectric liquid,under the condi tion of a certain range of ultrasonic effects,the discharge debris can be evacuated from the sparking gap more effectively by the cavitation effect,which can reduce the chance of abnormal discharge and improve the quality of the product surface.Firstly,according to characteristics of ultrasonic cavitation effect,what influence that diverse ultrasonic parameters(ultrasonic frequency,ultrasonic sound pressure amplitude)and different liquid properties have on cavitation bubbles movement in the liquid w ere studied by numerical simulation and analysis.The applicable ultrasonic parameters were obtained after the cavitation bubbles were broken,which provided a theoretical basis for the application of ultrasonic in dielectric liquid.Secondly,based on the above simulation results,the distribution of ultrasonic cavitation field in dielectric liquid was studied refer to the method of aluminum foil erosion.The attenuation rules of ultrasonic effect in the EDM dielectric liquid were explored,and the effect scope of ultrasound was determined,providing a reference for the following experiment of EDM with ultrasonic-assisted vibration of the dielectric fluid.Finally,according to above results of numerical simulation and the aluminum foil test,the cavitation effects of three ultrasonic frequencies on the microstructure of the surface was investigated,employing NAK80 die steel as the test material.The results showed that by promoting the movement of the discharge debris in electrical processing,the ultrasonic-assisted vibration of dielectric fluid can reduce the occurrence of abnormal discharge,reduce surface defects caused by the carbon deposition and re-solidified metals,which can improve the uniformity of the microstructure in surface of the workpiece a nd promote the machining quality.