Simulation And Experimental Study Of Temperature Field In Vertical Ultrasonic EDM

With the continuous development of modern special materials,all industries,including aerospace,have increasingly high requirements for material performance.A variety of high strength,high melting point,high hardness and more brittle metal materials are widely used.However,there is a significant shortage of traditional machining for special materials.The traditional machining of special materials has obvious shortcomings.In recent years,the birth of new composite machining,such as ultrasonic vibration-assisted EDM,has solved the problem of machining special materials that are difficult to cut,thus attracting widespread attention from researchers.This paper focuses on the key technologies related to vertical ultrasonic-assisted EDM of TC4 titanium alloy,and the research mainly includes the following aspects:(1)Based on the fact that the inter-pole voltage changes with the discharge gap during ultrasonic vibration-assisted EDM,the discharge energy model for ultrasonic vibrationassisted EDM is established.Combined with heat transfer theory to analyze the heat transfer theory of TC4 titanium alloy,the energy models of single-pulse EDM and ultrasonic vibration-assisted EDM containing parameters of voltage,current and discharge time as well as the Gaussian heat source model were established.(2)EDM is a transient,non-linear heat transfer process.Based on the analysis of ultrasonic vibration-assisted EDM energy model,Gaussian heat source model and heat transfer model theoretically,the transient thermodynamic solution of ultrasonic-assisted EDM is performed using the finite element method.A single-pulse ultrasonic-assisted EDM temperature field model is established,and the model is solved and the material removal volume is analyzed to provide reliable theoretical support for the development of ultrasonic vibration-assisted EDM.(3)The electrode end motion paths during vertical ultrasonic vibration-assisted EDM are analyzed and the voltage waveforms,material removal rates and surface quality of vertical ultrasonic vibration-assisted EDM are experimentally derived.The results show that the application of vertical ultrasonic vibration improves the probability of EDM breakdown through the discharge channel.The transient reduction of the discharge gap makes the transient heat flux increase suddenly,which changes the EDM discharge voltage and then affects the discharge energy of a single pulse.Second,the experiments of vertical ultrasonic vibration-assisted EDM found that there is a maximum discharge gap for EDM,and the maximum discharge gap differs for different discharge currents.When the ultrasonic vibration amplitude is within the maximum discharge gap,the material removal rate increases with the increase of amplitude,and when the ultrasonic vibration amplitude is larger than the maximum discharge gap,the material removal rate decreases with the increase of amplitude.