Technical Research For Laser-Assisted Machining Of Zircon Ceramics

Structure ceramics have many excellent properties,such as fine abrasionresistance and corrosion resistance, lower thermal conductivity, and excellent metalmatching expansion coefficient, so they are getting more and more applications inmachine,automabile and other modern industrial fields,such as diesel engine pistontop stem and head, lining, bearing. However, due to the brittleness of the structuralceramics, they are easy cause brittle failure and bad surface finish in processing, andthe hardness decided to the violently wear of the tool when traditional machining.Traditionally, to ensure the ideal precision and surface quality of the products,usually choose grinding process to remove a small amount of materials in finallyprocess, And when need to remove a lot of material, the inherent low materialremoval efficiency and corrosive processing conditions of grinding lead to extendingthe processing time and surface damage, Other forming methods, such as abrasivewater jet, ultrasonic machining and laser processing, the weakness of low removalefficiency decided its not fit for mass production. The difficulty and the high cost ofthe current machining methods obstructed extensive application of the structuralceramics components.Funded on the Jilin university basic scientific research project, the thesisexplored the laser-assistted machining method. through laser heating workpiecesurface before the machining, soften the material processing zone, made the yieldstrength less than the fracture strength, realized the material removal mechanismchange from brittle fracture to plastic deformation, to achieve the purpose ofmachining structural ceramics effectively. The research in this thesis mainly include:1. The thesis established the mathematical models of laser irradiate and heattranfer based on laser heating and heat conduction theory.2. Research the affects of the workpiece temperature by laser powers and cuttingspeeds through finite element method, provided practical theory basis for select andoptimization of the reasonable heating parameters and processing parameters.3. Set up a laser-assisted machining test system and processed the cuttingexperiment. In the experiments a Nd：YAG laser was used to heat the workpiece, CBN turning tools were used to machine the workpiece, dynamometer was used to measurethe three-axis force online, and electron microscopy was used to observe chips andtool wear. It has been measured the surface roughness after each cutting.The test and simulation results have shown that compared with traditionalmachining laser assisted machining of zirconia ceramics effectively reduces thecutting force, increases tool life, improves the quality of machined surface.