Study On Parameters Optimization Of Ultrasonic Vibration Turning Of High-strength Aluminum Alloy

The continuous development of science and technology has promoted the upgrading the manufacturing industry structure.The modernization of the country puts forward higher requirements for mechanical materials and processing technology.High performance and light weight of materials,high precision and high efficiency of manufacturing technique have become the development direction of mechanical processing industry.High-strength aluminum alloy has many comprehensive properties such as small density,high toughness,excellent thermal conductivity and erosion resistance.It has been widely used in the various fields of industrial production.However,the high hardness of this kind of material results in a larger cutting force during the turning process.Good plasticity,toughness and strong adhesion lead to built-up edge on the rake face of the tool.The above factors aggravate the wear of the tool,even reduce turning efficiency and processing surface quality of the workpiece.On the basis of the theories of ultrasonic vibration assisted turning,this paper investigates the ultrasonic vibration cutting performance of high-strength aluminum alloy Al7050 such as cutting force,cutting temperature and other aspects with the help of the finite element numerical simulation.Furthermore,the technological parameters of ultrasonic vibration turning aluminum alloy were optimized by using Taguchi experimental design method.The primary contents and conclusions can be listed as follows:(1)Theoretical analysis of ultrasonic vibration turning technology.This paper expounds the basic motion principle between tool and workpiece during ultrasonic vibration turning process,the kinematic relationship between tool and workpiece is analyzed in detail.The theory of "tool-workpiece contact ratio" is emphatically expounded.It is deduced that vibration parameters of cutting tools and cutting speed have important influence on the toolworkpiece contact ratio.The results show that in order to effectively reduce the contact rate between the tool and the workpiece,a larger vibration frequency or amplitude should be adopted in an appropriate range,or the cutting speed should be reduced.(2)The establishment of finite element model for ultrasonic vibration cutting.Combining the primary theoris of ultrasonic vibration assisted turning with the fundamental principle of finite element simulation,the finite element model of ultrasonic vibration turning based on adaptive meshing technology used ALE method is established by selecting the appropriate material constitutive model and chip friction model.On this basis,the cutting experiment was organized,and the rationality of the simulation model was verified by comparing the relative error between the experiment value and the simulation value of cutting forces.(3)The analysis of finite element simulation for ultrasonic vibration cutting.In the light of finite element models of ultrasonic vibration assisted cutting,firstly,the difference of the action mechanism between the tool and the workpiece is revealed at the micro level through comparing the difference of Mises stress distribution between ultrasonic vibration turning and conventional cutting.Secondly,the cutting characteristics of "suppressing vibration with vibration" for ultrasonic vibration cutting are revealed through the comparative study of instantaneous cutting forces between ultrasonic vibration cutting and ordinary cutting,so the dynamic stability of the cutting process is effectively improved by using ultrasonic vibration turning.Finally,the influences of vibration frequency,amplitude and cutting speed on the average cutting forces in ultrasonic vibration cutting are studied respectively by using single factor experiment method.(4)Experimental study on ultrasonic vibration turning.In order to verify the reliability of the finite element model,ultrasonic vibration turning experiment is carried out.Complete the overall design of the experimental platform,and reasonably select sensors and experimental devices to build ultrasonic vibration cutting experimental platform,organize cutting experiments,and verify the finite element model by comparing the simulation results of cutting forces with the experimental results.(5)The parameters optimization of ultrasonic vibration cutting process for highstrength aluminum alloy.In this part,the effect of main parameters(such as vibration frequency,amplitude,cutting speed,cutting depth and feed rate)on average cutting force in ultrasonic vibration assisted turning process of Al7050-T7451 is studied on the basis of Taguchi’s experimental design,and the optimal parameter combination is determined by smaller signal-to-noise ratio.Finally,the predicted value by using Taguchi experimental design model is compared with simulation value of cutting force,and the relative error is within a reasonable range.,so the effectiveness of the optimization model is confirmed.This topic enriches the research and application of ultrasonic vibration turning technology.It provides a new idea for precision and efficient cutting of high strength aluminum alloy.It is of great significance to further promote the application of aluminum alloy and further expand the ultrasonic vibration cutting technology.