Mechanism Analysis And Experimental Study Of Ultrasonic Vibration Assisted Milling For Titanium Alloy

With the rapid development of China's aviation industry,the demand for titanium alloys is also increasing.Due to its excellent physical properties,titanium alloys are also widely used in civil passenger,automotive,medical and chemical industries.In view of the good performance and broad application prospects of titanium alloys,domestic and foreign scholars have carried out extensive exploration and research on their processing methods and processing quality.The large chemical activity and low thermal conductivity of titanium alloys make it a typical difficult material to be processed.The traditional processing method has low working efficiency and low surface quality when cutting titanium alloy.Therefore,ultrasonic vibration assisted milling is introduced into the field of processing titanium alloys.Thereby,the cutting force,the cutting heat,the tool wear can be reduced,the machining efficiency can be improved,and the surface quality of the workpiece can be improved.This topic starts from the kinematics of ultrasonic vibration assisted milling.Through theoretical modeling,simulation and experiment,as well as the comparative analysis of ordinary milling and ultrasonic milling,the advantages of ultrasonic vibration assisted milling in processing titanium alloy are explored.The mechanism of cutting force,tool wear and surface quality of ultrasonic vibration assisted milling is also studied.It provides a theoretical basis for the future research of ultrasonic vibration assisted milling of titanium alloy.The specific research contents of this topic are as follows:(1)Through the study of the kinematics of ultrasonic vibration assisted milling,the mathematical model of the motion trajectory of ordinary milling and ultrasonic vibration assisted milling was established and simulated.The contact rate between the tool and the workpiece during ultrasonic machining was modeled and simulated.The influence of processing factors on the contact rate was obtained,and the change and relationship between the contact rate of 1 D and 2D ultrasonic milling were compared.(2)Based on the analysis of ultrasonic vibration assisted milling kinematics,combined with the bevel cutting force model,the cutting force model of ultrasonic vibration assisted milling was established.The cutting force coefficient was obtained by an experimental method.Comparative simulation and experimental verification of common milling force and ultrasonic milling force were carried out.The effects of different cutting factors and cutting parameters on ultrasonic milling force were analyzed.Thus,a method for predicting ultrasonic vibration assisted milling force is obtained.(3)For the tool wear problem of ultrasonic vibration assisted milling,a comparative experiment of ordinary milling and ultrasonic milling was designed to analyze the tool wear under three machining modes.Several types of tool breakage that existed during ultrasonic milling were discovered.The mechanism of tool wear was studied by scanning electron microscopy and energy spectrum analysis of the tools involved in ultrasonic milling.In combination with the cause of tool wear,measures to reduce tool wear are proposed.Collect and observe the chips produced by normal milling and ultrasonic milling.The difference in chip form and the cause of formation were analyzed.(4)For the study of surface quality of ultrasonic vibration assisted milling,a mathematical model of the surface topography of the workpiece during ultrasonic vibration assisted milling is first established.The surface topography of the workpiece was simulated and the experimental results were effectively predicted.The surface morphology of ordinary milling and ultrasonic milling was compared.The influence of processing parameters on the surface roughness of the workpiece was studied by experimental methods.The change of mechanical properties of the workpiece surface after ultrasonic vibration is applied is also explored.