Surface Topography Prediction And Simulation Of Optical Parts In Ultra-precision Milling

To ultra-precision machining of optical parts, simulation of machined surface topography is very important, because it directly affects surface quality and in particular the surface roughness. Due to people's understanding of the ultra-precision milling mechanism is still in its infancy stage, existing prediction models of surface topography fail to accurately reflect machined surface topography and the change law of machined surface topography with machining parameters. Though the study of scallop height on the machined surface in ultra-precision milling, a prediction model of ultra-precision milling surface topography has been established and issues related with parameters optimization in ultra-precision milling have been also studied. Main research contents of this paper are as followings.In full understanding of characteristics of ultra-precision milling and the forming mechanism of machined surface topography, surface scallop height along the feed direction is confirmed to be the most important factor to machined surface topography. A prediction model of ultra-precision milling surface roughness has been established based on the mechanism of machined surface topography. Scallop height of every point on the machined surface can be calculated through the projection method. Then, machined surface topography can be predicted by scallop height of points on the machined surface.Based on the prediction model of the ultra-precision milling surface topography, effects of parameters such as the radius of the ball end milling cutter, feed per tooth and path-interval to the machined surface roughness of free form surface lens have been studied. And the change law of machining parameters affecting surface scallop height can also be got. By analyzing the simulation results, it can be easy to see that feed per tooth and path-interval are the most important parameters affecting the machined surface topography in ultra-precision machining.Orthogonal tests are used to optimize parameters such as radius of the ball end milling cutter, federate per tooth and path-interval etc. With two optimization indexes of machining precision and efficiency, two groups of optimum machining parameters are got in this paper's orthogonal tests finally.In use of the ultra-precision milling surface topography simulation and optimization module, the function of simulating machined surface has been realized, the prediction model of machined surface topography has been confirmed and the function of parameter optimizing with two optimization indexes of machining precision and efficiency has been also realized.