Research On Tool Wear Modeling And Hole Making Process Optimization For Small Hole Machining Of SiCp/Al Composite Material

SiC particle reinforced aluminum matrix(SiCp/Al)composites have a series of outstanding advantages,such as light weight,high strength,high elastic modulus,low ductility and low thermal expansion.They are widely used in aerospace,automobile and precision electronic components.However,for the small hole drilling of SiCp/Al composites,hard reinforced particles will lead to the decline of hole accuracy and severe tool wear.Therefore,this paper mainly studies the tool wear mechanism in drilling and the influence of tool wear on cutting force,and establishes the tool wear model and drilling force model respectively.Based on the experimental results,a systematic small hole drilling process and optimization parameters of SiCp/Al composites are designed to improve the hole machining accuracy and reduce tool wear.The main contents of this paper are as follows:(1)A tool wear rate model considering the particle characteristics of SiCp/Al composites is established.The tool wear caused by two body abrasive wear,three body rolling wear and adhesive wear are calculated.In the modeling process,the characteristics of reinforced particles and the geometry of twist drill are specially considered.Through experiments,the correction coefficients in the proposed model are identified,and the wear rate curve and tool wear morphology curve are verified.The results show that the average error of the wear rate curve in this paper is 8.34%,and the tool wear morphology prediction curve is also in good agreement with the actual curve.The influence of machining parameters on tool wear is explored by drawing the response surface diagram.The analysis shows that the spindle speed is directly proportional to the wear rate,but has little effect on the final wear morphology of the tool;The feed rate determines the final wear morphology of the tool.The larger the feed rate is,the smaller the wear band width is.(2)The drilling force model of SiCp/Al composites considering tool wear is established.The twist drill is divided into the major cutting edge,the outer edge of the chisel edge and the extrusion area of the chisel edge.The force analysis of the rake/flank face of the chisel edge of the major cutting edge and the outer edge of the chisel edge and the extrusion area are carried out in detail.The influence of the continuous wear of the tool flank on the total drilling force is mainly considered in the model.The experimental results show that the average error of the proposed model is 4.2%;The drilling force model considering tool wear can accurately reflect the increasing trend of drilling force with the increase of cutting time;The contribution of different areas to the total drilling force under different machining parameters is compared.It can be seen that the contribution rate of the rake face is the largest,the contribution rate of the flank decreases with the increase of the feed rate,and the contribution rate of the chisel edge extrusion area is always the smallest.(3)A set of systematic SiCp/Al hole drilling technology has been determined through experiments.The results show that,compared with traditional machining,adding a backing plate at the bottom of the workpiece can simply and effectively reduce the height of outlet burr;ultrasonic vibration assisted machining and the introduction of cutting fluid can improve the hole machining accuracy and reduce tool wear.The machining parameters are optimized for hole wall accuracy and tool wear.Combined with particle swarm optimization algorithm,response surface graph and Pareto optimal solution set idea,the better machining parameters are determined and verified by experiments.