Research On The Polishing Process Of Complex Surface

The new generation optical system has higher requirements for surface quality and machining accuracy of complex optical surface elements. The application of complex surface can make the optical system with the characteristics of flexible design, excellent performance, compact structure and simple assembly etc. The increasing complexity of the work-piece surface, however, it will increase the difficulty of processing. Polishing is usually used as the last step of optical surface processing, which has important effects on the surface quality and machining accuracy of optical surface. The polishing of complex optical surface takes the surface finishing, removing the subsurface damage as the main target. The surface polishing quality of complex surface and polishing strategy selection, machine tool precision, surface measurement method, polishing path planning, dwell time, the determination of polishing liquid and polishing tools, etc. are closely related. This paper mainly from for aspects that are path planning, calculation of machining allowance, calculation of polishing dwell time and determination of the material removal region to study the polishing process of complex optical surface.Accurately calculating the machining allowance of the trajectory points is the key to accurately calculate the dwell time of the polishing process. Considering free surface can’t be determined by the mathematical analytical formula, the machining allowance is obtained by the method of interpolation and local surface fitting algorithm, which has obvious advantages compared to other computational methods. The results are applied to the subsequent algorithm of calculating the dwell time, and the dwell time of the polishing process is accurately obtained. Subsequently, the machining allowance is applied to the calculation of dwell time with the least square method, which achieved good results.The case of the material removal area and the theoretical contact area is not consistent verified by the spot polishing experiment. Based on the error analysis between material removal area and the theoretical contact area, the material removal area modifying coefficient is introduced. The modifying coefficient is applied to the concentric circle path planning algorithm on the rotational symmetric aspheric surface. This algorithm plays a larger role in improving the uniformity of the overlap-rate between adjacent tracks, which helps to improve the precision and efficiency of ultra-precision polishing.When the ordinary concentric circle trajectory is used to polish the rotational symmetric aspheric surface, the machining surface often appears the phenomenon of uniform machining which is caused a large curvature variation of rotational symmetric aspheric surface. By optimizing the concentric circle trajectory, the modifying-overlap-rate is introduced which is based on the definition of overlap-rate algorithm between adjacent tracks and modifying coefficient. Based on this algorithm, the uniform-overlap-rate of the removal area between adjacent paths in a certain range is realized and the quantitative uniform-overlap-rate is introduced, which effectively improve the uniformity and stability of material removal.