Research On The Key Technology Of Vibration-assisted Polishing For Optical Elements

In recent years,with the rapid development of aerospace technology,optoelectronic technology,atomic energy technology and laser technology,the performance requirements of optical components are more and more high.In the fields of advanced science and technology mentioned above,optical components are widely used,but the surface quality of optical components is required to be high.Therefore,ultra-precision machining of optical components is a challenge.In the processing technology of optical elements,polishing is a very critical step in the processing of optical elements,polishing can eliminate the surface scratches and surface damage of optical elements,improve the surface quality of optical elements.Based on the traditional polishing,the vibration-assisted polishing in this paper gives two-dimensional vibration to the optical element on the plane.The auxiliary two-dimensional non-resonant motion can improve the surface quality of the workpiece and improve the material removal rate.The research contents of this paper are as follows:(1)A two-degree-of-freedom flexible decoupling device driven by a piezoelectric actuator was developed.Based on the two-stage lever amplification mechanism,a symmetric structure is adopted to reduce the occurrence of coupling and parasitic motion.The stiffness and natural frequency of the device were calculated by MCM and Lagrange methods.In order to obtain better performance of the two-degree-of-freedom flexible decoupling device,the structure size of the device was optimized by using whale swarm optimization algorithm(WOA).Meanwhile,the statics and modal analysis of the device were carried out based on ABAQUS simulation.In order to study the experimental performance of the two-degree-of-freedom flexible decoupling device,relevant performance tests were carried out,including stroke,sweep frequency,resolution test,step and hysteresis response test.(2)Study on material removal characteristics of vibration-assisted polishing.Firstly,based on the kinematics principle,the processing principle of vibration-assisted polishing method was analyzed,and the motion velocity of abrasive particles was obtained.At the same time,the contact area of polishing process was analyzed.Micronano indentation and scratch experiments of Si C workpiece were carried out to explore the law of brittle-plastic transition of the material.The number of effective abrasive particles was calculated by the normal distribution of abrasive particles.Based on the indentation and scratch test results,the critical cutting depth of Si C material was analyzed.Based on the theory of elastoplastic deformation,the contact deformation between a single abrasive particle and the workpiece was analyzed to explore the elastoplastic deformation of the material.Finally,based on the Preston equation,the material removal model of vibration-assisted polishing was established.(3)In order to verify the effectiveness of the proposed vibration-assisted polishing method,a comparison experiment between non-vibration polishing and vibration-assisted polishing was conducted.After the experiment,the surface morphology of the workpiece was characterized by white light interferometer and scanning electron microscope,and the improvement effect of vibration-assisted polishing on the surface quality of the workpiece was discussed.At the same time,an electronic balance was used to record the changes of workpiece quality before and after the experiment to explore the rule between vibration parameters and material removal rate.Finally,the material removal rate experimental data and the material removal rate model simulation results of vibration assisted polishing were statistically analyzed to verify the accuracy of the material removal rate model.