Warpage Deformation Control And Optimization Method For The Thin-walled Lens

At present, the replacement rate of plastic products gets more and more quickly. The tendency of product design is to be large size, light weight, thin thickness and so on. The improved product design thought has induced a series o f problems, such as warpage, localized shrinkage, residual stress. In particular, warpage defect is particularly prominent for thin- walled lens. The warpage of thin-walled lens’ mechanism is extremely complex and the relationship between the amount of defo rmation and the process parameters is non- linear, so it is difficult to optimize its warpage. Because of the fact that the great demand of lens, if the warpage amount is out of range, it will affect processing, assembly and the beauty of the products, even cause economic disaster, so how to solve the problem tends to be extremely important.Generally there are two main ways to improve the warpage of thin- walled lens: mold-repairing and numerical Simulation of CAE and Orthogonal binding assay. Mold-repairing is heavily dependent on practical experience,it may affect the mold production cycle or resulting in mold scrapped. Although the orthogonal experiment method can use CAE software simulation and experiment to improve warpage, it can only obtain optimum process parameters, so we need to find more advanced technology to reduce warpage of thin- walled lens, through which we can find the best combination of process parameters to provide guidance for the actual production. In this article, we combined MO LDFLOW, single parameter variables, orthogonal experiment analysis with MATLAB optimization algorithm to reduce the amount of warpage of thin- walled lens’ problems. Now we illustrate the relationship between the process parameters and warpage, so that we can get the optimal process parameters to direct the theory research and actual application.1) Establish the thin-walled parts injection molding finite element model. We use MOLDFLOW to analysis different kinds of defects and search the relevant solutions, especially focuses on the warpage problem of molding process. Moreover, we study the influence of dwell time, holding pressure, injection time, mold temperature and melt temperature on the thin- walled lens.2) On the basic of MOLDFLOW numerical simulation, we stud ied the influence of five process parameters on the warpage of the products. By means of range analysis and variance analysis method, we draw a conclusion of the orders for this five process parameters,which affected the warpage strength of plastic parts.That is as follows: holding pressure>dwell time>melt temperature>injection time>mold temperature, and influence factors are as follows: 33.3 %、28.5 %、14.1 %、8.0 %、7.0 %. Finally, we got the optimum parameters of thin- walled injection molding process.3) On the basic of MATLAB, the non- linear BP neural network model between process parameters and warpage has been established. What’s more, we got the best combination of process parameters by combining the model and Genetic Algorithm. Using the simulation process parameters, the warpage of the lens’ working surface is only about 0.9mm, and it can meet the requirements of the processes.4) Use experiments to verify the correctness of the optimum process parameters. In the experiments, the amount of warpage is no more than 0.8 mm. The error is less, when compare with the theoretical predictions, and it can meet the actual needs of the production, so this method is entirely feasible in practical applications.