Molding Process Simulation And Injection Compression Mould Of Aspheric Plastic Lenses

Aspheric plastic lens has significant advantages in the improvements of imaging quality, simplification of the structure, decrease of the equipment weight and mass production, and the application prospect in both military and civil fields is very broad. However, because the aspheric plastic lens has uneven shrinkage for the large change in the wall thickness and is very easy to be warped, so it is difficult to get the high quality of aspheric plastic lenses using the conventional injection molding technology. The precision mold design and the molding process are the key technologies for molding the high quality aspheric plastic lens.At first, in order to obtain the molding method of aspheric plastic lenses, the research statues of aspheric plastic lenses molding method, the injection compression molding technology and the injection molding CAE technology are analyzed respectively. A new molding method of the larger diameter aspheric plastic lens using the injection compression technology is proposed in this paper based on summary of lessons from others’research results.Then, a set of injection compression mold is designed based on the theory of polymer molding shrinkage and injection compression molding technology. The gating system of this mold can be clamped for the closing of the cavity at first. The compression function of the mold is accomplished by the injection molding machine of the second mold-clamping, and the mold can also be used for the injection molding experiment on the general injection molding machine. The gating system of the mold is designed based on the MoldFlow simulation software, and the gating system of S-curve runners and secondary gates are identified as the best gating system.In the end, the molding process for the aspheric plastic lens is studied based on the MoldFlow simulation software. The relationship between the injection compression process parameters and the volumetric shrinkage of the product is studied by the single factor test. And the test results show that mold temperature, melt temperature, and compression force have more effects on the volumetric shrinkage of the parts during the molding process; compression delay time and compression speed have a little effect; injection time and compression distance have no effect. The flow and waipage simulation test of injection molding and injection compression molding are carried out respectively based on MoldFlow by the orthogonal experiment design, and their optimal molding process parameters combination are obtained respectively. Under the optimum process conditions, the simulation results of injection molding and injection compression molding are compared with each other. The contrast results show that the product of injection compression molding is better than the one of injection molding in parts quality, volumetric shrinkage, and warpage deformation.