| As a new material developed in recent years,SiCp/Al composite material effectively combines the toughness and ductility of plastic materials with the high strength and high modulus of SiC ceramics.It has excellent properties such as high specific strength,good thermal stability,and wear resistance,and has broad application prospects in the fields of aerospace,transportation,and national defense construction.However,due to the plastic aluminum-based material and hard and brittle SiC ceramic particles contained in the SiCp/Al composite have very different processing characteristics,it is easy to cause instability in the machining process,sharp tool wear and deterioration of surface quality,which hinder the large-scale application of SiCp/Al composite.The quality of the processed surface is closely related to the degree of cognition of the material processing mechanism.Since the domestic research on SiCp/Al composite started relatively late,there is a lack of in-depth understanding of the basic machining mechanism.Through high-speed milling experiment,55 vol.%SiCp/A356 Al composite with an average particle diameter of about 45 μm is taken as the research object,the basic research is conducted on the influence of the changes of cutting speed,depth of cutting and workpiece feed on the surface quality and cutting force.The main results are as follows:Due to the large number of defects such as pits and scratches on the processed surface of the 55 vol.%SiCp/A356 Al composite,the three-dimensional surface roughness is more suitable for characterizing the processed surface morphology than the two-dimensional surface roughness.With the increase of milling speed or workpiece feed,surface roughness increases firstly and then decreases;the increased milling depth will cause an increase in surface roughness.Among the three processing parameters,workpiece feed has the largest effect on surface roughness,followed by milling depth,and milling speed has the least.The broken SiC particles will leave pits on the processed surface;SiC debris will leave scratches,protuberance and other defects on the processed surface under the pressure of the tool;the squeezing effect of the tool will also leave micro-cracks on the surface of the matrix phase and the smearing formed by the plastic flow of the matrix phase.As the milling speed increases,the cutting force decreases,but the increase in milling depth or workpiece feed will cause the cutting force to increase.The increase of the milling depth will cause the tangential force,radial force and axial force to increase at the same time,while the increase in the workpiece feed mainly causes the tangential force to increase.During the machining process,the tangential force dominates,followed by the axial force,and finally the radial force;the milling depth has the largest influence on the cutting force,followed by the workpiece feed,and finally the milling speed. |
