Fabrication Of Nanomaterial-impregnated Vitrified CBN Grinding Wheel In Strong Magnetic Field And Wheel Grinding Performances

With the recently released strategy named "Made in China 2025",the importance of manufacturing engineering has been strongly highlighted.Among all the manufacturing technologies,vitrified CBN grinding wheels and the corresponding grinding techniques have been considered as one of the most crucial ones,which can be evidenced by the surged numbers of both published papers and industrial application cases.However,most of the high-performance and high-end vitrified CBN products can only be provided by famous industrial companies in developed countries.To fill this gap,this thesis attempts to introduce both nano-materials and strong-magnetic-field-sintering technologies into the fabrication of vitrified CBN grinding wheels.Except for the wheel fabrication,large numbers of grinding trials are also performed to evaluate the produced wheel performances in comparison with two conventional vitrified CBN grinding wheels,in terms of machined surface integrity,grinding force/force ratio,and temperature.To understand the superior wheel performances,theoretical modeling metholodgies of the ground surface topography,grinding force,and grinding temperature considering varied grain-workpiece micro interactions are also proposed.The studied topics in this thesis might include:(1)Unlike routinely employing the abrasive products recommended by abrasive companies,this thesis performs systematic experiments to comprehensively evaluate and compare the quality and performance of several kinds of domestic and international abrasive products.Also,this thesis innovatively introduces several kinds of nano-materials into the vitrified bond mixture.More importantly,the optimised component weight ratios of the nanomaterial-impregnated vitrified bond mixture are also determined based on the orthogonal experiment design method.The results show that,thanks to the high specific surface energy and chemical activity,nano-materials are effective to produce more superior bond matrix in terms of both fabrication manufacturability and mechanical properties;(2)This thesis also innovatively introduces the strong-magnetic-field-sintering technology into the wheel fabrication process.The grinding wheel with preferentially-oriented grains as well as compactly-textured bond matrix is successfully produced.Besides,the optimised sintering temperature curve,and strong magnetic field loading/unloading parameters are also obtained based on the orthogonal experiment design method;(3)To understand the superior performances of the produced wheel,theoretical modeling metholodgies for ground surface topography,grinding force,and grinding temperature considering grain-workpiece micro interactions are proposed,providing a theoretical approach to study the relationship between the observed superior performances and the unique wheel microstructure;(4)By performing large numbers of grinding experiments for both metals(#45 steel and Ti-alloy)and brittle materials(monocrystalline silicon and optical glass),the produced wheel is proved to be superior regarding machined surface quality,grinding force,and temperature,in comparison with two conventional vitrified CBN grinding wheels from two famous international companies.