The Research Of Plastic Lens Injection Compression Molding

As an important optical component,plastic lens has been widely used in national economy.With the increasing requirements on the quality of plastic lenses,traditional injection molding is difficult to produce a lens that meets the requirements.It is of great significance to study the influence of the forming process on the dimensional stability and optical performance of plastic lenses.The paper chooses plastic lenses as the research object and uses injection compression molding method.The effect of injection compression process parameters on the performance of plastic lenses was investigated.The main research work is as follows:(1)According to the size and performance requirements of the lens,based on the Moldflow software,the mold flow analysis was performed on two different flow channels of a two-cavity lens mold,and the final selection of the processing mode of the Sprue was considered comprehensively.Determine the cavity structure of the lens injection compression mold,number of cavity arrangement,gating system,mold temperature control system,and compression structure.The mold can not only perform injection compression molding experiments,but also complete traditional injection molding experiments.(2)Based on the Moldflow simulation analysis,single factor experiments were used to study the influence of important process parameters such as compression distance,melt temperature and compression delay time on the volume shrinkage and residual stress,and the causes of the influence laws were analyzed.Orthogonal experimental methods,combined with range analysis and variance analysis,obtained the optimal combination of volume shrinkage and residual stress.The importance of the process parameters was analyzed.The results show that the melt temperature has the greatest effect on the volume shrinkage,the compression delay time has the greatest effect on the residual stress,and the compressive force has little effect on the two performance indexes.(3)Using the designed injection-compression mold and using PMMA as experimental material,the injection-compression process was analyzed.The transmittance of the plastic lens was measured to study the influence of the process parameters on the light transmittance.The method of comparing the actual size of the measuring lens with the size of the cavity is used to obtain the volume shrinkage of the lens under different process parameters.The residual stress of the product was measured indirectly using a stress measuring instrument.According to the principle of photoelasticity,the optical path difference index indirectly reflects the internal stress distribution of the lens and achieves the purpose of verifying the simulation results.(4)Comparing the injection compression molding and injection molding lenses to compare the difference for the volume shrinkage and residual stress of the two molding methods.