The Study Of The Mechanism Of Cavity Filling And Residual Stress Of Lens Arrays In Heat Pressing Process

Heat molding technology is a precise replication technique. Compared with the traditional processing techniques, such as turning, milling, planning and grinding, heat molding technology takes many advantages in high efficiency, low cost as well as forming a periodic array elements. It can be mainly used in the processing of optical components, such as thin lenses with small diameter, high-order aspheric lenses, lens arrays, diffractive optical elements and freeform optics components. Nowadays, with the wide application of the lens array, heat molding precise replication technology is being paid more and more attention. The research on heat molding precise replication technology of lens array is very urgent as well.Based on the two-dimensional finite element model and the theoretical simulation, the investigation is performed in such aspects as the filling mechanism of the lens array cavities in pressing stage of heat molding, residual stress distribution of molded parts in pressing stage and the relationship between the maximum residual stress of molded parts and the heat molding process parameters. The results show that:(1)The filling rate of the mold cavities near the edge of mold is lower than that near the middle;(2) The higher the temperature is the greater the rate of mold cavities filling is;(3) The higher the speed is the larger the filling rate is;(4) The residual stress in molded lens array near the center is small and the distribution is uniform, the residual stress in molded lens array near the edges is large and the distribution is nonuniform;(5) The maximum residual stress in molded lens array reduces when the temperature rises, but the law is not simple linear. The slope are quite different between the left and right of 570℃;(6) The maximum residual stress in molded lens array reduces when the speed reduces, but the law is not simple linear. The slope are quite different between the left and right of 0.012mm/s;(7) The maximum residual stress in molded lens array can be connected with the thickness of the glass.