Simulation And Experiment Study Of Burr Formation In Micro Milling Oxygen-free Copper Micro Structures

With the rapid development of high-precision fields such as the defense industry and the increasing demand for micro-miniaturized products,the miniaturization of products has become a global trend.Micro-milling is a micro-small product processing technology,which has the advantages of wide material adaptability,high processing efficiency,and machinability in complex three-dimensional structure.However,if the process parameters or strategies are not properly selected,serious defects such as burrs will occur on the surface of the workpiece,which will directly affect the life and performance of the workpiece.Therefore,this project aims at the formation of burrs and the methods for minimizing burrs in micro-milling of oxygen-free copper through theoretical modeling,finite element simulation,and experimental analysis for characteristic samples with small structures.Based on the theoretical model of micro-milling machining,the effect of size effect and negative rake angle on the formation of chips and burrs was studied.The influence of undeformed chip thickness and the radius of tool radius on burr formation was obtained,and when the ratio of both is approximately 1,the burr formation size can be minimized.Through the method of finite element simulation and experimental verification,the influence of tool parameters and milling parameters on the formation of burrs in the micro-groove milling process was studied.The effect of different process parameters on the burr formation position and burr shape was analyzed.The results showed that the tool parameters had an influence on the burr formation mainly by controlling the chip shape,flow direction and curling state.The feed rate per tooth in the milling parameters had the greatest influence on the exit burr formation,while the milling depth had the greatest influence on the top burr,and the influence of both is positively related.In this way,the best combination of process parameters can be summarized to minimize burr formation.Based on the characteristic samples,the representative spherical and column structures were processed using the best process parameters.The effects of machining time,machining sequence,milling method,and tool path on the surface roughness and edge burr formation of the features were researched.The results showed that increasing machining time will increase tool wear,resulting in serious size effects,then increasing burr formation.The machining sequence of the top to side of the characteristic column can reduce the deformation of the workpiece,and the use of up milling can reduce the formation of edge burrs.Compared with the Z-shaped trajectory,the circular machining trajectory of the flat cutter can reduce the surface roughness of the workpiece,and the burrs on the cylinder edge can be removed by means of an empty knife almost without damaging the workpiece.Using the optimal process parameters and processing strategies,the required sample parts of the project are processed,and finally the experimental results meet the sample requirements.