Research On Mill-grinding And Its Key Technology Of SiC Particle Reinforced Aluminum Matrix Composites

SiC particle reinforced aluminum matrix composites (SiCp/Al) has been widelyused in aerospace, advanced weapon systems, automobile and other fields, due to itsexcellent properties. With the development of aerospace technology in recent years,the demand for high volume fraction SiCp/Al increases gradually. Many parts whichhave complex geometrical features such as thin walls or deep cavities, require highaccuracy. When machining these parts with cemented carbide tools, not only the toolwear is seriously, but the corner of workpiece exists edge-breaking and machinedsurface occurs chatter due to the tool vibration. The mill-grinding processing used inthis thesis has such advantages as the milling and grinding being suitable forcomplex structure and for hard brittle materials, respectively, which has obvioussuperiority especially in machining of complex shape, high accuracy and thin wallparts manufactued by high volume fraction SiCp/Al. Therefore, research onmill-grinding and its correlative technologies of high volume fraction SiCp/Al hasimportant theoretical significance and broad application prospects.In view of the present machining situation of SiCp/Al, an electroplated diamondmill-grinding tool with spiral grooves was designed based on the principle andcharacteristics of mill-grinding processing as well as the properties of the SiCp/Al,which can be suitable for machining high volume fraction SiCp/Al. The influence oftool geometry parameters and machining parameters on mill-grinding force wasstudied by orthogonal experiment. Through two examples of typical parts, thefeasibility of the mill-grinding processing and designed mill-grinding tool formachining high volume fraction was further verified, and the results showed thismill-grinding tool can improve the effect of cooling and chip removal, andefficiency of mill-grinding high volume fraction SiCp/Al.According to the interaction model of single diamond and SiC particles inSiCp/Al, the chip formation process in mill-grinding SiCp/Al was studied. Sometypical chip shapes including curved chip, huddled chip, schistose chip, strip chipand blocky chip were gained, and their forming process was analyzed. According tosingle diamond scratching experiment of SiCp/Al and brittle fracture mechanicstheory, the removal mechanism of SiC particle was explained.On the basis of the study on material removal mechanism of SiCp/Al, a cuttingforce mathematical prediction model was developed considering the SiC particlefractured force in mill-grinding proces. Then the developed model was verified bythe experiments. Also the distribution of chip deformation component force, frictioncomponent force and particle fracture with the change of machining parameters, such as cutting speed, feed rate and milling width, was calculated through thistheoretical model.The surface formation mechanism and surface morphology characteristics ofSiCp/Al, and the influence characteristics of grit size mill-grinding and machiningparameters on the surface morphology were analyzed. The surface roughness modelof the SiCp/Al mill-grinding was proposed, and the application conditions of thedeveloped model were given. Then the validity of the model was confirmed throughexperiment. Finally, the machining parameters using vitrified bonded diamond toolfor gaining high machined surface quality in mill-grinding SiCp/Al were gainedbased on analyzing the mill-grinding tool, material removal mode and machiningparameters, which has guiding significance for subsequent precision machining ofSiCp/Al.