Design And Molding Experiment Research Of Injection Compression Mould For Aspheric Plastic Lenses

Aspheric plastic lenses can correct aberration in optics system, achieve high qualitative images, simplify the instrument’s structure, make the instrument lighter, have good processability, achieve complex structures easily, and can also reduce costs by the batched production. So the aspheric Plastic Lenses play an increasingly important role in space, medical and electronic field.Due to the uneven thickness of aspheric plastic lenses, and melt will form a greater pressure differences at the end of material flow and sprue gate in general injection molding. So the aspheric plastic lenses made by injection molding have a lower quality, and they easily generate a larger internal stress and birefringence. So it is necessary to adopt scientific processing methods, precision processing tools and reasonable processing technology, to produce the aspheric plastic lenses with high precision and big size. According to all three of these aspects, this article will study how to choose injection compression molding technology, how to design injection compression molding and multi stage injection experiment and compressed parameters orthogonal experiment.First, during mould design process, this article research on how to arrange the location of springs and how to design the form of cooling channels and the shape of branch sprues, aiming at improving the product processing quality, the stability of processing and the mould’s service life. According to ANSYS stress analysis and optimization, this article determines the spring rate and location of injection mould. According to the characteristic of cores, this article designs blowout cooling means aiming at cooling product evenly. According to the analysis the impact of sprue’s shape on product, this article chooses S type sprue finally, aiming at making the temperature of melt flowing into the cavity more even.Second, this article studies the parameters of injection compression molding technology, including the multistage injection of injection compression. According to the orthogonal experiment, this article finds out the better process parameters of product surface accuracy and birefringence. Based on the above, one can draw a conclusion that the melt injection speed should keep medium speed, and the interference fringes of injection compression molding product spreads from a center evenly, reflecting that the internal stress of injection compression molding distributes evenly.According to the comparison of the center birefringence and interference fringes images between injection molding product and injection compression molding product, this article finds that the third and fifth injection speed lower due to the existence of compression motion, namely injection compression molding technology can improve the whole injection speed during the filling stage of injection-compression molding, so the melt should fill in the cavity quickly based on a relatively low but maximum speed and reduce the impact of pressure-holding on the product quality. Based on the above, one can draw a conclusion that the injection-compression molding has obvious advantage on the product birefringence, but has no obvious advantage on the product weight, and the injection compression molding can reduce the whole birefringence effectively, and make the internal stress of whole product especially spruce gate more even.