Research On Laser Micro Drilling And Milling Surface Morphology

Micro machinery is becoming more and more important in the future society,thus the micro machining technology of the microstructure has become one of the focuses in research.The laser micro machining has good characteristics such as the high concentrated energy,effective controllability, and non-touch machining, therefore, the laser micro processing has been widely applied in the manufacturing field.The laser micro processing surface morphology has enormous differences compared with traditional machining and the electrical discharge machining surfaces because its surface lies between isotropic and anisotropic surfaces. Meanwhile, the surface morphology has tight connection with surface property. Thus, the surface morphology can objectively reflect the formation mechanism. It directly influences the engineering surface function properties,especially the surface friction and the lubrication characteristic. Therefore, the research of laser micro machining surface morphology is of great significance. The laser micro machining surface quality has not been systematically and completely researched and evaluated at present, which restrains the development of the laser micro processing technology.The thesis designs a four-axis precision worktable for the accuracy requirement of the laser micro drilling and milling. It requires that the worktable should have four degrees of freedom, the repetitive positioning accuracy is less than 2μm, and the resolution power can reach 0.1 μm, which can satisfy the laser micro drilling and milling motion and accuracy requirements. Meanwhile,it uses the finite element analysis software ANSYS to simulate the drilling data of the SUS301 material. It makes a numerical simulation and analyzes the technological parameter effects on the heat affected zone, the hole depth and its aperture.Thus,it can provide a reliable theoretical guidance to the selection of the experiment parameters. It also measures the pulse energy of the YAG laser machine, which can lay a foundation for the research on the laser micro drilling and milling parameters. Then, it builds a mathematical model of single-pulse laser micro machining to describe the geometrical shape of the micro drilling hole. The surface morphology mathematical model of the laser micro milling is developed to provide a theory basis for the surface micro-topography assessment.The experiment studied the spring steel 65Mn, the stainless steel SUS301, and ceramic Al2O3 by drilling micro pore with different pulse energy and numbers. It used the scanning electron microscope and the super scene depth microscope to observe and measure data. Combined with the laser drilling mechanism, the thesis analyzes the effects of two parameters of the pulse energy and numbers on the blind holes and the through-hole surfaces and studies the changing rules of the hole depth and diameter with the two parameters in different materials.Then, it not only studies the influences on the milling depth and surface morphology, but also the pulse energy,scanning speed,cutting layer,frequency, and scanning gap,the five parameters effects on the removed depth and surface morphology. Finally, it discusses the effects of the processing geometric accuracy based on the machine system precision error, the laser time delay error, the perpendicularity error, and the scanning path; it proposes the improvement measures for each factor.