Theoretical And Experimental Research On Disc Hydrodynamic Polishing

Nowadays, with the rapid development o f science and technology, the demand of optical elements gradually toward large-scale and super smooth surfaces, computer controlled optical surfacing technology and non-contact polishing technology ha ve been rapidly developed. In order to maintain the advantages of high precision, good surface quality and improve the processing efficiency, this paper presents the processing way of planar hydrodynamic polishing, which changes the point contact and line contact of the traditional hydrodynamic polishing into surface contact, and the method is researched meticulously in the basic theory and process experiment.First of all, based on the fluid dynamics knowledge, the relationships between some parameters in the process of planar hydrodynamic polishing, including the pressure, bearing capacity, flow rate, rotational speed and film thickness, are derived. Also the film thickness control equation is obtained. The theoretical model is numerically simulated by the current popular CFD software, and then is compared with the theoretical result to verify the correctness of the theoretical equation, which provides guidance for the follow-up control mode of experiment.Secondly, in order to realize the stable and controllable polishing process and reduce the precision demand of mechanical equipment when manufacturing and assembling, the uneven film thickness is analyzed by FLUENT. It is shown that the uneven film thickness will provide partial load torque to correct the pose of the tool. Accordingly, it can be learned that the self-correcting tool is theoretically feasible. In order to ensure the self- correcting ability of tool in the mechanical structure, two kinds of flexible structure are designed in this paper, which are proved to be feasible based on the dynamic simulation.Finally, the test bench is set up to complete the planar hydrodynamic polishing experiment. The pose of tool is tested, and through the comparison and analysis of the data, the half frequency vibration phenomenon of tool is found, which proves the existence and dynamic stability of the film, and the amplitude of tool increases along with the increase of the rotational speed. Compared with the data before and after polishing, it is demonstrated the machining process can realize the ultra-precision polishing.