Research on processing technology of grinding aspheric workpiece in the five-axis machine tool

Abstract

Aspheric optical components have been widely used recently because of their unique advantages. Thus, it is necessary to investigate processing technology of such aspheric parts. In this paper, an aspherical mirror is ground with cup wheel in five-axis computer numerical control (CNC) machine tool and corresponding processes were investigated. To improve machining efficiency and reduce tool wear, the workpiece is firstly ground to be a spherical mirror, and then it is ground to be the aspheric contour. The best fitting spherical mathematical equation is derived by the axisymmetric quadratic aspheric generatrix equation. A ∅90 mm aspheric mirror was ground with cup wheel with five-axis computer numerical control (CNC) machine tool. The aspheric curve is processed into a paraboloid shape. The experimental results show that the surface profile of the aspherical lens is consistent with the designed profile, and the peak value (PV) value of the error is 4.77μm. Such results can be accepted in consideration of working allowance for polishing. According to the experimental results, the cause of the error was analysed and methods for improving precision were proposed.