SPH Simulation And Experimental Study On Micro Ball-end Milling Of Aluminum Alloy Al7075

Aluminum alloys have been regular aerospace and automotive material for its low density,high thermal and electrical conductivity,high corrosion resistance,high friction coefficient,excellent formability,low melting point,and a wide range of possible surface treatments.Ball end milling is commonly used in finish milling of dies,molds,impellers,turbine blades and other parts with complex sculpture surfaces,it has been wildly used in industries such as aerospace,biomedical,and automotive.Micro scale milling demands micro ball end milling as a finishing process to manufacture micro components like micro impellors,however,micro scale milling is not simply downsized from the conventional operation but has its own characteristics such as size effects.The mechanisms studies of micro ball end milling are very necessary.The thesis focuses on the micro ball end milling process of aluminum alloy,conducted a series of SPH simulations and experiments to reveal its mechanisms.The main contents are as follows:(1)The orthogonal cutting SPH simulations of Al7075-T651.An orthogonal cutting model was developed based on the SPH method in the engineering software ANSYS/LSDYNA.By modifying the model parameters according to other researchers' published conclusions,the cutting model acquired a reasonable computational time and accuracy.The minimum uncut chip thickness of Al7075-T651 under orthogonal cutting and the effects of friction coefficients to the simulation results are studied based on the developed model.(2)The 3D ball-end milling SPH models were developed to simulate the milling process of Al7075-T651.The ball end cutter was modelled using reverse engineering technology based on the scanned cutter morphology.The 3D ball end milling model was developed based on the studied orthogonal cutting SPH model.The 3D model was validate through the comparison of chip morphology and cutting force form experiment and simulation.(3)The influence of cutting parameters on cutting force was studied by micro ball-end milling experiments.The size effect during micro ball-end milling were analyzed by feed rate single factor experiments.The chip morphology and milled surface morphology were studied based on the SEM pictures.