Study Of Cutting Temperature Of Titanium Alloys For Quasi-intermittent Vibration Assisted Swing Cutting

Titanium alloys are widely used in high-tech fields such as aviation and aerospace because of their high strength,low density,high temperature and corrosion resistance.However,the inherent low thermal conductivity and high chemical reactivity of titanium alloy make it easy to produce high temperature,rapid tool wear and poor surface integrity.Therefore,the study of titanium alloy processing has important theoretical significance and practical value.Quasi-intermittent vibration assisted swing cutting(QVASC)is a non-traditional advanced manufacturing technology,its quasi-intermittent cutting and friction reversal and other characteristics can reduce cutting temperature,ease tool wear.Although the QVASC technology is becoming more and more mature,there are still many unknown phenomena of QVASC technology,such as the generation of cutting heat,the temperature distribution of tool surface and tool wear.Therefore,in this paper,the cutting heat and tool temperature in QVASC cutting process of titanium alloy are deeply and systematically studied from three aspects: theoretical analysis,numerical model and experimental verification,the effects of various cutting parameters and vibration parameters on cutting force and cutting temperature are analyzed.The main research contents are as follows:(1)The kinematics and friction of QVASC are analyzed in order to study the influence of tool swing on cutting process.The kinematics characteristics of cutting process are analyzed from the view of QVASC cutting principle,and the displacement equation and velocity equation of tool swing are derived.Based on the shear angle model,the relationship among cutting velocity,shear velocity,friction velocity and tool swing velocity in QVASC are obtained.The QVASC friction force was analyzed based on the force of chips,and the shear force and friction force were calculated based on the Johnson-Cook constitutive model of workpiece material,which laid the foundation for the subsequent modeling of cutting temperature.(2)A cutting temperature prediction model considering QVASC cutting characteristics is proposed to further reveal the cutting mechanism of QVASC.The heat generation and heat transfer model of QVASC process is established.According to the distribution of friction shear stress and the existence of heat convection with or without environment,the heat flow distribution on the tool rake surface is divided into four regions,the heat flux of the cutting tool is calculated respectively.On this basis,the tool temperature of QVASC was solved by using the heat balance equation in the form of partial differential equation,and the prediction model of QVASC cutting temperature was established.The influence of various factors on the cutting tool temperature is analyzed by the model,which provides a theoretical reference for the following experiments.(3)A three-dimensional numerical model of QVASC and Ordinary Cutting(OC)of titanium alloy is established,and comparative study of QVASC and OC and analysis of mechanical and thermal characteristics in cutting process were carried out.The thermal-mechanical coupling simulation of QVASC and OC cutting titanium alloy was carried out,and the setting and selection of tool swing cutting,material model and failure criterion,friction model and heat transfer model ensured that the simulation was more consistent with the actual cutting process.The stress,strain,friction,cutting force and cutting temperature were taken as the main output parameters concerned in the simulation,and the simulation results of cutting force and tool temperature under different cutting speed,tool swing frequency and angle are analyzed and studied.(4)In order to verify the validity of the theoretical analysis and numerical model,the cutting temperature experiment of QVASC machining titanium alloy was carried out.The comparative experiments of QVASC and OC are carried out to verify the conclusions of the numerical model and further confirm the advantages of QVASC in cutting temperature reduction.The effects of cutting depth,cutting speed,tool swing frequency and amplitude on cutting temperature were investigated by single factor method,and the experimental values were compared with the theoretical values,and the error between the experimental values and the theoretical values was found to be in an acceptable range,thus proving the availability of the theoretical model.