Simulation And Experimental Study Of Glass Molding For Small Aspherical Lens

With the development of science and technology, the small aspherical glass lens have been widely used in national defense, industial, civil, medical and other fields, and become key components of science and technology. The glass molding process(GMP) has high machining efficiency, good forming quality, and has the advantage of mass production, so the GMP has replaced the traditional glass lens processing gradually.There are two main problems of the GMP currently: Firstly, molding process causes stress inside the lens, and too large stress lead to bad effects of qualities of the lens. Secondly, there is a shape deviation after annealing and cooling, and the shape deviation influences the image quality of lens. Due to the shortages of the GMP, the finite element simulation models of glass lens molding process with MSC. Marc were established. Reasons which influence stress distribution and shape deviation of the lens were studied by finite element simulation. Besides, a molding process experiment of small single-convex aspherical glass lens was carried out.The main contents of this paper are presented as follows:1. Based on the generalized Maxwell model, the finite element simulation models of glass lens molding were established in heating and soaking stage, molding stage, annealing stage and cooling stage. Finite element simulation was used to analyze the influence of glass molding parameters in four stages on stress respectively.2. Based on finite element simulation model, shape deviation of the glass lens between annealing stage and cooling stage was compared. Parameters which influence shape deviation were studied, such as aspherical surface parameters, structural relaxation parameters and thermal expansion coefficient. Shape diviation of the lens of multi-step-heating and multi-step-annealing conditions was predicted. Shape deviation among steep-meniscus lens, bi-convex lens and single-convex lens was compared.3. Glass molding experiments of small single-convex aspherical lens were carried out on seven-step GMP machine. Shape deviation and surface roughness were measured and compared among dies before molding process, dies after molding process, and molding glass lens. Shape deviation of the lens between experimental measurements and simulation prediction were verified to be consistency. Reasons which cause shape deviation and surface roughness of molding glass lens were analyzed.