微小非球面光学模具单点斜轴误差补偿磨削

Single-point Inclined-axis Error Compensation Grinding for Small Aspheric Optical Molds

针对微小非球面光学透镜模具的纳米单点斜轴误差补偿磨削进行研究。通过分析比较传统的直交轴磨削法,提出微小非曲面光学模具的单点斜轴磨削方式,有效避免微细砂轮在加工微小非球面时发生干涉情况;采用单点恒定磨削方式提高微小非球面磨削的稳定性及精度。通过分析磨削区域内微细砂轮与微小非球面的干涉情况,从而合理计算并选用较高强度的微细砂轮。提出微小非球面误差补偿磨削策略,分析砂轮的对心误差(x轴向和y轴向)对形状精度的影响,采用法向残余误差补偿的方法对加工后的形状误差进行超精密补偿磨削。利用超精密磨床对口径为2 mm的超硬热压模具碳化钨材料的微小非球面进行纳米单点斜轴误差补偿磨削试验,经过三次超精密磨削及误差补偿循环,其形状精度PV从1 034 nm改善至146 nm,表面粗糙度达到Ra2.19 nm。

A single-point inclined-axis grinding technique and error compensation method of aspheric mold are studied.After analyzing and comparing the traditional perpendicular grinding method,a the single-point inclined-axis grinding mode is proposed for avoiding the interference between small grinding wheel and small aperture aspheric mold,and the stability and grinding accuracy can be improved.Small fine grinding wheel with high intension is chosen by analyzing the interference of grinding area and the grinding wheel.An error compensation strategy is proposed based on ultra-precision single-point inclined-axis grinding.The x-directional and y-directional de-centering errors are considered to correct the new centering position of grinding wheel.The random form error is compensated based on proposed normal residual error compensation.An experimental test is conducted to grind an aspherical tungsten carbide mold with aperture 2 mm on an ultra-precision grinder.The profile accuracy is gradually improved from PV 1 034 nm to 146 nm after two-time compensation cycle,and the surface roughness is Ra 2.19 nm.