Experimental Research On Ultrasonic Composite Mixed Media Electrical Discharge Machining Of TC4 Alloy

EDM is widely used in the machining of high hardness,high elasticity,high viscosity and brittle conductive materials.In general EDM,the increase of machining speed will cause the increase of surface roughness,the thickness of recast layer,the increase of surface micro cracks and other problems,which need further treatment,and affect the machining efficiency To some extent,mixing powder in the medium can effectively reduce the concentrated discharge and obtain better surface quality during high current machining.However,when the concentration of mixing powder is increased,the fluidity of the medium becomes poor and it is easy to deposit on the machining surface and affect the normal discharge.In order to solve the above problems,in this paper,ultrasonic is loaded on the tool electrode,and the high frequency ultrasonic vibration is used to speed up the inter electrode dielectric cycle,so as to improve the inter electrode discharge The electric environment can improve the efficiency and surface quality of powder mixed EDMFirstly,the influence of different discharge forms,breakdown characteristics of mixed dielectric,powder addition on discharge process and ultrasonic on EDM are analyzed.The theoretical analysis shows that when the powder and air are mixed in the dielectric,it is easier to breakdown,which increases the discharge gap and reduces the parasitic capacitance between the electrode and the workpiece;the ultrasonic disturbance accelerates the cycle of the dielectric between the electrodes,the ultrasonic vibration increases the effective breakdown range of the dielectric,which is conducive to improving the discharge efficiency;the ultrasonic cavitation improves the efficiency of the discharge and maintains a good discharge environment between the electrodes;According to the needs of the test,the ultrasonic vibration device of tool electrode is designed and manufactured by ANSYSSecondly,with TC4 alloy as the workpiece,the central composite test of 7-level single factor and 5-level 5-factor was designed.Through the single factor contrast test,it is found that the surface roughness Ra value of the workpiece in the medium with large current(16A?20A)and large pulse width(70?s?90?s)is smaller than that in the ordinary medium,and the processing speed is also greatly improved.When the small pulse(15?s?30?s)is processed,the surface quality and processing efficiency of the workpiece are higher than those in the ordinary medium;when the concentration of the mixed powder exceeds 20g/L,the surface quality and processing efficiency of the workpiece are reduced,and when the ultrasonic is loaded The effective concentration of mixed powder can reach 30g/L.ultrasonic vibration is conducive to the uniform suspension of powder and the reduction of depositionFinally,the influence of various factors on the machining was studied by the central composite test.The significance of each factor is obtained by variance analysis of the test results,and the regression equation is established.The interaction between each factor and the influence law of each factor on machining are obtained by response surface analysis.The experimental results show that ultrasonic plays a significant role in the process of mixed dielectric EDM,and the machining speed is increased by an average of 20.7%,and the surface roughness Ra value is decreased by an average of 11.1%.