| Due to their low density and heat expansion coefficient, superior wear, corrosionresistance and anti-oxidization, and high-temperature strength, structural ceramicssuch as alumina, silicon nitride and zirconia are getting more and more applications inautomobile, chemical engineering, aerospace aviation, medical applications and otherindustrial fields. However, machining of ceramic materials with traditional methods isvery difficult to produce precision ceramic components due to their high hardness andbrittleness. Currently, Laser-assisted machining is a kind of hybrid machining process,which enables the focused laser beam to heat the partial component to dramaticallymodify its processability and then reduce tool wear, improve surface quality andprocessing efficiency before using the conventional cutting tool to remove the workpieces. Consequently laser-assisted machining is a promising and effective technologyto fabricate ceramics materials and other high hardness materials.In this paper, theoretical and experimental investigations have been conducted onpulse-laser assisted turning of hot-press96alumina ceramics. Firstly, based on thetheory of heat transfer, the model of finite element is built. Then the temperaturefields of alumina ceramics are simulated with finite element software ANSYS and theinfluences on the temperature distribution by changing technical parameters,including pulse laser power, the rotating speed of workpiece and the frequency ofpulse-laser is analyzed. Secondly, experiment platform is built and experiments onlaser-assisted machining are carried on to provide data for next research. At last, thesurface roughness and surface defect of cylinders of alumina ceramics machiningunder different technical parameters are detected and analyzed. The main conclusionsare listed as the followings:（1）According to the simulation result, the temperature of workpiece increaseswith time in zigzag, while the temperature fields of its surface basically exhibitselliptic-like shape and the location of the maximum temperature appears behind thelaser spot center. And the inner temperature field basically exhibits parabolic-likeshape and its depth direction gets less influence. The simulation has also shown theinfluence of different parameters on the temperature distribution of cross section andlongitudinal section of cylinder and there is a certain depth of soften area when thesoften temperature (500℃) is specified.（2）Based on the Taguchi orthogonal experiment, the test results reveal the following as optimum operating conditions to achieve good surface roughness: arotational speed of510rpm, a pulse laser power of50W, a pulse frequency of50KHzand a feed of0.01mm/r. The contribution percentages of the pulse laser power,rotational speed, pulse frequency and feed to performance are19.42%,25.21%,13.39%and41.98%.（3）Surface roughness of workpiece is measured and Surface defect underdifferent machining parameters is investigated. After analyzing the surface roughnessand surface defect of the workpiece, the research finds that there will be better surfacequality with no crack, less surface damage and pin defects if increases the laser power,rotational speed, and pulse frequency while decreases the feed. The feasibility ofpulse-laser assisted machining is proved and satisfactory surface quality can beachieved. |
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