Experimental study on elastic deformation machining process for aspheric surface glass

Elastic deformation machining is a fabrication method that exploits the elastic deformation properties of materials under stress. Coupled with plane lapping machining process, this new fabrication method is suitable for machining complex aspheric surfaces. Upon completion of the machining process, the workpiece under process will be shaped into a desired surface form. The elastic deformation machining has several advantages over traditional fabrication methods, i.e., high machining compatibility and high fidelity of material property during machining process. The subject of this study is to determine the surface shape of the finished glass workpiece after the lapping process of the elastic deformation machining. The experimental results were compared with theoretical calculations. In the case when the vacuum pressure is 50 kPa, the maximum deviation value between the deformation curves from the theoretical calculation and the experiment results is within 62 μm. In order to improve the precision of form surface, the vacuum pressure is modified from 50 to 42 kPa. This reduction corresponds to a change of workpiece thickness when it is lapped. The results of the change of vacuum pressure show that the form accuracy produced is improved significantly and agrees very well with theoretical calculations. The maximum deviation in this case is 1.6 μm. The study indicates that the experimental plane lapping setup that exploits the material elasticity property can be utilized to fabricate aspheric lenses with axisymmetric surface and low complexity.