Research On Atmospheric Pressure Cold Plasma Jet Assisted Micro-Milling TC4 Titanium Alloy

Atmospheric pressure cold plasma jet assisted micro-milling is a machining method that injects cold plasma jet generated by discharged gas to the cutting zone to have effect on cooling and lubrication.The cold plasma jet assisted micro-milling can significantly improve the cooling and lubricating environment of the cutting area,and has promising application prospect.On the basis of analyzing different micro-milling methods,this thesis started from the generation mechanism and method of cold plasma jet.A series of theoretical and experimental research were then carried out.The discharge parameters of cold plasma jet,and the effect of cold plasma jet on the solid surface wettability,mechanical properties,cutting force,cutting temperature and surface integrity were analyzed and studied.The main research work of this thesis can be summarized as follows:In order to develop cold plasma jet which can be effectively transported to the toolworkpiece interface,the effects of different discharge parameters on the size and temperature of cold plasma jets were investigated using self-designed atmospheric pressure cold plasma jet generator.When the discharge form was bare electrode,the discharge voltage was 1.53 kV,the nitrogen flow rate was 12 L/min and the outlet diameter of nozzle was 2.5 mm,a uniform,stable and relatively longer plasma jet could be obtained.The temperature of the plasma jet was near to the room temperature.In order to explore the mechanism of cold plasma jet assisted cutting,on the basis of analyzing the effect of cold plasma jet on the solid surface wettability,the plasma modification experiment and tensile test of TC4 titanium alloy under cold plasma jet atmosphere were conducted.The results showed that the atmospheric pressure cold plasma jet could effectively improve wettability of the metal surface,while the surface micromorphology were not obviously influenced.Additionally,the cold plasma jet could obviously decrease rupture strength of metal materials,thereby providing theoretical basis for improving machinability of cold plasma jet assisted micro-milling TC4.In order to investigate the effect of cold plasma jet on the machinability of micro-milling TC4 titanium alloy,micro-milling experiments were conducted under various atmospheres.The influence regularities of cold plasma jet on cutting force,cutting temperature,surface roughness,surface micromorphology and residual stress were studied.The results showed that the cold plasma jet could reduce the cutting force and temperature of the cutting area during the micro-milling process of TC4 titanium alloy,and effectively improve surface quality of the machined surface.The combination of cold plasma jet and fog cooling had a better performance.