小口径双非球面硫系玻璃镜片精密热压成形模具制造

Precision GHP Mold Manufacturing for Dual Aspherical Chalcogenide Glass Lens with Small Aperture

将小口径双非球面硫系玻璃镜片精密热压成形过程的有限元分析与模具非球面轮廓预测及补偿相结合,提高热压成形模具的制备效率与精度,满足该类镜片高精度批量制造的需求。根据硫系玻璃热压过程中的热传递、黏弹性、应力松弛行为与结构松弛特性的分析,获得玻璃高温热力学性能参数,建立镜片热压成形的有限元模型;对仿真获得的镜片非球面轮廓曲线进行RBF函数拟合,并据此对模具模腔的轮廓偏移进行补偿;基于补偿后的模具非球面参数,对成形模具进行超精密加工与检测;采用所制备的精密成形模具,在多工位热压成形机床上压制小口径双非球面硫系玻璃镜片,并对成形镜片的检测数据进行相关分析。研究结果表明:经三次补偿后,镜片非球面ASP1与ASP2的轮廓偏移量h仿真值均小于0.25μm;加工后模具上、下模腔的非球面ASP1与ASP2的粗糙度RMS值分别为3.5 nm、5.6 nm,形状精度PV值分别为31.5 nm、50.4 nm;实验所压制的成形镜片,其非球面ASP1、ASP2的检测数据基本满足PV值不大于0.2μm、Ra≤0.04μm以及h≤1μm的精度要求。

In order to improve the preparation efficiency and accuracy of GHP mold and meet the demands of high-precision batch manufacturing of the lens,the FEA method was combined with mold contouring prediction and compensation for precision GHP of dual aspherical chalcogenide glass lens with small aperture.According to the analysis of heat transfer,viscoelasticity,stress relaxation behavior,and structural relaxation characteristics for the chalcogenide glass in the processes of GHP,the glass thermodynamic performance parameters under high temperature were obtained,and FEA model for GHP was also established.The RBF(radial basis function)was adopted to fit the simulated aspherical curves of the lens,and the contour deviation of the mold cavity was compensated.According to compensated mold aspherical parameters,GHP mold was machined and tested precisely.The dual aspherical chalcogenide glass lens with small aperture were pressed on a multi-station GHP machine by using the prepared mold,and the testing data of the lens were also analyzed.The results show that the simulated values of the contour deviation h of lens aspheric surfaces ASP1 and ASP2 are both less than 0.25μm after three compensations.The roughness RMS values of mold ASP1 and ASP2 are as 3.5 nm and 5.6 nm respectively,and their form error PV values are 31.5 nm and 50.4 nm respectively.The measured values of pressed lens ASP1 and ASP2 basically meet the requirements of error PV≤0.2μm,Ra≤0.04μm and h≤1μm.