Research On Laser Assisted Milling Technical Of Silicon Nitride Ceramic

Engineering ceramic materials with such good characteristic as high strength, highhardness and high temperature resistance, corrosion resistance, low density, especiallyhot-pressing sintering silicon nitride ceramics which is one of the hardest substance inthe world, is widely used in mechanical, chemical, aerospace and other industrial fields.because engineering ceramics material is easily brittle fracture , the conventionalmachining methods are hard to achieve high quality machining, and the productioncosts is high. Laser assisted machining technology is a new kind of compoundmachining method of engineering ceramics material,which has far-reaching meaning ondeveloping engineering ceramics processing method , improving the machining qualityand reducing cost.In this paper, the temperature field of heating hot-pressing sintering silicon nitrideceramics with laser is studyed through finite element simulation.the influence of laserheating parameters on the temperature field was studyed,and the heating parameterswhich can make the cutting area of workpiece softening are obtained;The laser assistedmilling system was set up and it is achieved that the milling of hot-pressing sinteringsilicon nitride ceramics.The experiment recults show that the quality of milling can begood by selecting the appropriate parameters.The mainly completed work andachievements is as follows:According to the heat transfer theory, a three-dimensional transient nonlinear finiteelement model of temperature field when heating silicon nitride ceramics material withlaser was set up. the nonlinear changes of the material thermal physical parameters andboundary conditions was considered in this model. The temperature field model wasverified through the temperature measuring experiments. The parameters of the modelwere revised through the experiment data and eventually the maximum error of thetemperature field modeling is 10%, the error when laser is moving is less than 5%.The influence of laser power, preheating time,and moving speed of laser spot onthe temperature field was researched by using the temperature field model,so is theinfluence of workpiece measurement; The softening depth and softening extent were calculated in the different parameter,which can provide reference to the selection of themachining parameters.The experiment system of laser assisted milling was set up,and achieve the laserassisted milling of hot-pressing sintering silicon nitride ceramics successfully,and theinfluence of laser power, moving speed of laser spot and cutting speed for milling wasstudyed. The results show that the cutting forde can be reduced and the machiningefficiency is more high than traditional machining methods. But the tool wear is stillserious and the form of tool wear is flaking wear of the back surface of tool; The surfaceroughness of workpiece can achieve Ra0.17-0.27μm by selecting the appropriateparameters,and there is no heat injury and crackle in the surface;The continuous chipsemerge in the milling process,which has some characteristics of the milling of plasticmaterials.