Complex Curved Surface Polishing Technology Based On Five-axis Machining Center

Currently, mirror parts of high quality are widely used in mold, optical, aviation industries and other fields. In order to achieve this machining requirement, polishing becomes a necessary process. However, the polishing process after NC milling of these parts mainly depends on manual operations. It is time-consuming and easily producing severe dependence on the worker’s experience which is difficult to maintain a stable polishing operation for a long time. Therefore, no matter from the perspective of productivity, cost or the stability of product quality, automatic polishing process is highly desirable in these fields. On this basis, we proposed an automatic polishing method based on five-axis machining center and it can be well applied to the mirror machining of complex curved surface.Firstly, we given the whole research process and constructed an automatic polishing system which integrates the polishing process with the milling process. In this part, the proposed research process contains machining system, theoretical modeling, path planning and experimental verification. At the same time, for the machining system, we proposed use the five-axis machining center platform with the suitable polishing tools. And we introduce several testing instruments using in this machining system.Secondly, based on the pressure distribution and material remove profile, we proposed the measures to maintain the uniform material removal of the parts. According to the relationship between the displacement of polishing disk and the force impacted on the polished part, the pressure distribution model within the contact zone is derived for both planar and curved surface polishing for specific process parameters. On this basis, the model of material removal profile along the vertical direction of feed is built for each polishing pass, and thus a suitable stepover size is further obtained so as to reduce the fluctuations of remove depth to most extent.Thirdly, we provided the path planning methods for the curved surface in this article. We proposed different schemes for pre-polishing and final-polishing process, and given the specific polishing path generation algorism based on adapted Hilbert’s curve which is used in the final-polishing path planning. Then, transform the obtained cutter contact paths to the cutter location paths, and the motions of equipment can be controlled base on concrete machine tool configuration.Finally, the polishing experiments for planar and curved surface were conducted. The results show that the proposed automatic polishing scheme is able of achieving a mirror effect surface and keep a good global uniformity. After final polishing, the measurement results of planar part and curved part are Ra=9.077nm and Ra=17.351nm respectively.