Study On Grinding Of SiC Ceramics Considering Abrasive Characteristics And Micro-hole Flaw

Ceramic materials have high hardness,high temperature resistance,corrosion resistance and other excellent properties.They are widely used in mechanical,aerospace,medical and other fields,and the demand for them is increasingly strong.With the increase of application and demand,the processing of ceramic materials is developing towards hig h qualit y and high efficiency.However,as a kind of hard and britt le materials,its processing and manufacturing becomes more difficult.At present,the main machining method of these materials is grinding.In grinding process,the randomness of grinding wheel topography,the nature of workpiece materials and the diversit y of processing parameters make the processing process complex and uncertain.The study of the effects of these characteristics on the machining process and result s will be helpful to understand the grinding mechanism,and provide theoretical support for improving the machining qualit y and efficiency.In this paper,physical experiment s and discrete element numerical simulat ion are used to study the influence of abrasive characterist ics and wheel shape on the grinding process.Considering the characterist ics of the workpiece material itself,a discrete element model of Si C ceramics with ellipt ical-hole flaws was established based on the experiment and the grinding of a single abrasive was studied.Finally,the effects of different grinding parameters on the surface and sub-surface damage of workpiece were studied by simulat ion and experiment.The main work of this paper is as follows:(1)Art ificial diamond abrasive grains and ceramic bond abrasive blocks were observed by ultra-depth three-dimensional microscope.The typical shape of abrasive and the distribut ion characterist ics of abrasive on the outer surface of grinding wheel were summarized,which laid a foundation for the establishment of model in the following simulation work.(2)Si C ceramic observe by optical microscope.The experimental results show that the main flaw t ype in the material is ellipt ical-hole flaw.Based on the experimental results,a discrete element model of Si C ce ramic containing ellipt ical-hole flaw was established,and the change of crack growth mode and mechanical response under compression was studied.(3)Based on the previous experiments,this paper describes the geometry of diamond grains,establishes three typical single grain models and workpiece models with mult i-hole flaw,and carries out grinding simulat ion.It is found that the inclinat ion and length diameter ratio of hole flaws have a certain influence on the grinding damage shape and grinding force of workpiece.(4)The geometric descript ion of diamond grinding wheel and the grinding wheel with uniform distribution of abrasive part icles was both established,and a lot of simulat ion work was invest igated by using the orthogonal method.The internal relationship between the shape of abrasive particles,the inclination angle of abrasive particles,the height of abrasive particles out of the edge and the grinding process was studied by means of range analysis and variance analysis,and the degree of these factors affecting the grinding process was also discussed in depth.(5)The discrete element model of grinding wheel with random part icle shape and distribut ion is established and the grinding simulat ion is carried out.By comparing with the experiment,the influence of grinding process parameters on the surface and subsurface damage of workpiece is studied.