Research Of Theory And Experiment On Cutting Force Of KDP Crystal In Ultra-Precision Machining

As an excellent nonlinear optics crystal, the Potassium Dihydrogen Phosphate(KDP) crystal is used in laser and nonlinear optics field, but KDP crystal is a kind of soft-brittle material, and its machining is difficult, so machining of KDP crystal is the key technology of ICF. Now, KDP crystal is usually machined with the ultra-precision machining technology. In the ultra-presicion cutting process of KDP crystal, the machined surface quality of KDP crystal is influenced by the coupling of the tremble arosed by cutting force and machine tool, to explore the machining methods that can reduce the influence of cutting force on surface roughness by the theoretical and experimental research of cutting force, it is very important to machined surface quality and fabrication of KDP crystal.Firstly, the mechanical properties of KDP crystal is analyzed in this paper, the effect of crystallographic orientation on mechanical properties is gotten. Then, according to the material properties of KDP crystal, a theoretic model of shear plane angle of KDP ultra-precision machining is built using the principle of the maximum specific energy of shear deformation.Secondly, a new ultra-precision cutting force model is established using the mechanism of surface formation. The relation of cutting force with several principal parameters is gotten, the law of cutting force variations is gotten in ultra-precision machining process. Then a group of optimum tool geometry parameters are obtained by optimization of cutting force through MATLAB, which make the surface quality achieve the best.Thirdly, the basic orthogonal micro-cutting process is researched based on the former researchers. Using gridding re-partition critertion, a chip separation rule is established . Under the consideration of the effect of rounded cutting edge radius on the micro-cutting process, a elastic-plastic coupled finite element orthogonal micro-cutting model is built up. With the help of commercial finite element analysis software MARC, a finite element simulation of cutting procedure is put into practice and the influence factors of cutting force of KDP crystal in ultra-precision cutting process is analysed. Finally, the cutting experiment of KDP crystal are produced in ultra-precision machine tool. In the process, the cutting force singnal is collected. Then, the cutting data is analysed with the help of computer in order to validate the influence of cutting parameters on cutting force. In the end, the cutting force model is validated by contrast theoretical results to experimental results.