Study on Ultra-Precision Grinding of Micro Aspherical Molding Dies for Optical Transmission Devices

本研究开发了一种新型的微细砂轮倾斜转轴磨削方法和磨削系统。通过机器上的单晶金刚石修整器将砂轮成形为直径0.8 mm的精确柱状形状。利用该系统对半径曲率约为0.7 mm的零件进行磨削试验，获得了0.1um P-V左右的形状精度和0.03um Ry以下的表面粗糙度，非球面光学元件的微型化是当前的发展趋势。为此，采用最大转速15×104rpm的超高速磨削主轴和半径曲率约0.3 mm的微砂轮对非球面进行了进一步微细化加工。在磨削试验中，对半径曲率小于0.3 mm的WO(硬质合金)模具进行了磨削试验，获得了约0.1um的P-V形状精度，模拟了砂轮半径误差和砂轮定位误差(水平和垂直方向)对工件形状精度的影响，并讨论了其补偿方法。并在非球面磨削试验中，对所提出的补偿方法磨削碳化钨的实例进行了检验。实验结果表明，本文提出的补偿方法是可行的。

In this study, a new grinding method and a grinding system with the inclined rotational axis of micro grinding wheel were developed. The wheel was formed to a precise columnar shape of 0.8 mm in the diameter by a single crystal diamond truer on the machine. By the developed system, in grinding test of the workpiece of about 0.7 mm radius curvature, the form accuracy of about 0.1 mum P-V and surface roughness of less than 0.03 mum Ry were obtained.Recent trend is the further micronization of aspherical optical components. Therefore further micronizing of aspherical surface was examined by the ultra-high speed grinding spindle of 15 * 104 rpm at the maximum rotational rate and micro wheel of about 0.3 mm in radius curvature. In the grinding test, WO (tungsten carbide) molding die of less than 0.3 mm radius curvature was tested and the form accuracy of about 0.1 mum P-V was obtained.Finally, the effects of the wheel radius error and the wheel positioning errors (horizontal and vertical directions) on the workpiece form accuracies are simulated and its compensation methods are discussed. And in the aspherical grinding tests, the grinding examples of tungsten carbide by using a proposed compensation methods are examined. From the experiments, it was clarified that the proposed compensation methods are useful.