FEM simulation and analysis on molding process of infrared aspheric lenses

Abstract

Glass molding press (GMP) is a kind of mass production method to manufacture infrared aspheric lenses made from chalcogenide. However, it's hard to determine the molding parameters during the GMP process because the lens forming is conducted under the high-temperature conditions. In this paper, the finite element method (FEM) is used to simulate the GMP process based on the general Maxwell viscoelastic model and thermo-rheologically simple property. During the simulation, 2-D axisymmetric FEM model is constructed according to the different pressing velocities and friction coefficients, which change from 0.01mm/s to 0.5mm/s and from 0.01 to 0.2, respectively. To improve the simulation accuracy, the heating and pressing steps are separate and the heated result is taken as the pre-state of pressing step. The final results show that the best molding conditions are 0.1~0.2mm/s in velocity and 0.1~0.15 in friction coefficient for the infrared aspheric lenses made from chalcogenide of Ge33As12Se55.