基于弹性固结磨料小工具的RB-SiC平面修形抛光工艺研究OA

The surface accuracy of silicon carbides is one of the important factors affecting the accuracy of optical systems.The traditional free abrasive figuring process has the disadvantages of low processing efficiency,poor stability of processing accuracy and complex process,which seriously restricts the efficiency and accuracy of silicon carbide surface figuring.In order to meet the requirements of high efficiency and high precision for the figuring of RB silicon carbide flat workpiece,a new figuring method of RB silicon carbides based on small elastic consolidation abrasive tool was proposed.A small elastic self-conditioning consolidation abrasive tool was designed and prepared.Based on Preston formula,the removal function model of the small elastic consolidation abrasive tool was established and verified,and the processing parameters of the tool were optimized by the orthogonal test.A figuring test of RB silicon carbide flat workpiece was carried out on a three-axis constant pressure CNC polishing platform. Based on the Preston theoretical equation,the removal function model of the small tool was established.The effects of rotational speed ratio and eccentricity on the Gaussian-like characteristics of the removal function were studied.The theoretical contour curve of the small tool removal function was in good agreement with the experimental contour curve.The abrasive parameters of the consolidation abrasive tool were optimized by the fixed-point polishing experiment,and the feasibility of replacing the free abrasive with the small tool with the abrasive particle size of 7-10 μm to complete the figuring of silicon carbides was verified. The process parameters optimization and stability of the removal function were studied.When the revolution speed was 125 r/min,the pressure was 0.125 MPa,the speed ratio was ‒2,and the eccentricity was 0.5,the comprehensive processing effect was the best.The stability of the removal function and the effect of polishing time on the removal function were studied under this set of parameters.The peak change rate of the maximum removal depth of the small tool stabilized within 5.6%within 30 min,and the material removal depth changed linearly with the dwell time,indicating that the material removal efficiency of the tool was constant,reflecting the excellent material removal stability of the elastic consolidation abrasive small tool. The experimental study of silicon carbide figuring with elastic consolidation abrasive small tool was carried out.The material removal model of small tool figuring silicon carbides and the solution model of small tool dwell time were constructed.The figuring experiment of silicon carbides was carried out on the three-axis CNC polishing platform.The PV value of the machined workpiece surface converged from 16.875λ(λ=632.8 nm)to 4.619λ,and the convergence efficiency reached 72.6%.The RMS value converged from 4.610λ to 0.868λ,and the convergence efficiency reached 81.2%.The average surface roughness reached Ra 0.084 μm. A removal function model for the small tool with elastically bonded abrasives has been established and verified through experiments.The experimental results show that replacing free abrasive polishing with this small tool meets the process indicators for the rough polishing and shaping of silicon carbides.After polishing and shaping,the roughness of silicon carbides is reduced,and the surface quality is significantly improved,which demonstrates the excellent polishing and shaping capabilities of the small tool with elastically bonded abrasives.