Research On Precision Turning Technology And Tool Wear Of SiCp/2024Al Composites

With the development of aerospace technology and the progress of national defense military technology,the performance of the material is being made a very demanding requirement.All aspects of the material with so excellent performance required that the traditional material has been far from meeting the demand,and the composites came into being.Silicon carbide particle reinforced aluminum matrix composites is a new composite material developed in recent years.It has the advantages of high specific strength,high specific modulus,corrosion resistance,high wear resistance,high thermal conductivity and excellent thermal properties,which makes particulate reinforced aluminum composite materials in aerospace,defense,instrumentation,electronics,automotive,sports and other fields having been widely used.The excellent properties of SiCp/Al composites are obtained by sacrificing the plasticity,toughness and machinability of the composites.Because of the low plasticity,especially the fraction of silicon carbide particles more than 40%,the composites shows brittle performance and belongs to typical difficult to process material.During the cutting process,the high hardness SiC particles have serious grinding effect on the tool,which causes the tool fail due to excessive wear and tear.Therefore,there is an urgent need to find a cost-effective process to solve the difficult problems,such as serious wear and tear,in the processing of composites,to enhance the application of silicon carbide particles reinforced aluminum composites and broaden the application areas.This thesis mainly focuses on the research of SiCp/Al composites precision turning technology and tool wear,and summarizes the following research results:Firstly,the physical and mechanical properties of the materials were studied by means of tensile compression test and Vickers indentation test.The physical and mechanical properties of Vol.45%SiCp/Al composites were studied deeply by theoretical analysis and fracture morphology.The brittle and plastic properties of the materials were obtained,which provides the theoretical basis for the selection of tool geometry parameters.Secondly,the influence of each process parameter and geometry parameters of the PCD tool on the surface quality was studied in detail,then the optimization of the cutting process parameters and the geometrical parameters of the PCD tool were realized,improving the quality of processing surface,which provides technical guarantee for deepening the wear mechanism and wear law of polycrystalline diamond tool.Finally,the theoretical prediction model of wear volume of polycrystalline diamond tool was established.And the correction calculation of the theoretical prediction data was carried out with the turning experiment of Vol.45%SiCp/Al composites.The wear pattern and wear law of polycrystalline diamond tool in precision turning process were studied further,which clarified the wear mechanism of the polycrystalline diamond tool and the main factors affecting the tool wear.The wear rate of polycrystalline diamond tool was reduced to the one-eighth through the process parameter optimization,which lays the technical foundation for improving the precision machining technology of high volume fraction SiCp/Al composites in China.