Research On The Effect Of Automotive Polycarbonate Windscreen Macro Geometric Imperfection On Angular Deviation

Polycarbonate is constantly challenging the inorganic glass in the automotive windscreen manufacturing field as a result of low density and excellent optical properties and mechanical properties. Large scale transparent polycarbonate pieces with complex surfaces were widely used in automotive windscreens and aircraft windscreen. Domestic research on automobile windscreen glass of polycarbonate focused on class A surface design, injection compression molding process and equipment. Little research was done on the optical properties. Domestic research on angular deviation was mainly concentrated in the windscreen glass fields about polycarbonate pieces. Optical angular deviation was the angle between the outgoing light and the angle of the incident light passing through a transparent specimen, which was one of the most important optical properties. The optical properties can be significantly improved by injection compression molding. Injection compression molding can effectively reduce the residual stress and make the shrinkage more uniform. Warpage, uneven thickness and other macro geometric imperfection can not be totally eliminated in the manufacture, which will affect the optical angular deviation of the final product. In addition, the geometrical shape itself will bring some angular deviation. The optical angular deviation contained both.In this paper the hyperbolic class A surface model of automobile front windscreen was designed based on the appearance of the car windscreen. The specific impact mechanism was studied between the geometry parameters of the car windscreen and the optical angular deviation. The law of macro geometric imperfection when produced through simulation and experimental study of three typical preparations by injection molding was studied. Warpage and uneven thickness were characterized, by which can get the relationship between macro geometric imperfection and optical angular deviation.The degree of warpage and uneven thickness of the front car windscreen can be peredicted with the study of the small piece, and the optical angular deviation can be predicted as well. The optical angular deviation of former car windscreen caused by geometrical shape itself was simulated by Lighttools. The optical angular deviation caused by geometrical shape itself and macro geometric imperfection together contributed the whole angular deviation of car windscreen, which can be verifed by the angular deviation test of the reduction ratio of the car windscreen.