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As in recent years, energy shortages, leading to rising prices of plastic raw materials, how to ensure product performance down to save plastic raw materials, is currently a hot research topic. Microcellular foam injection molding is in this context the development and study of a new technology, the technology adopted in the plastic melt in supercritical CO2 or N2, such that a dense micropores formed in the inside of the injection-molded article, the size of 5 ~ 100μm presence of micropores can be significant savings in plastic raw materials, plastic products with good mechanical properties. This technology has been widely used in household appliances, aerospace, automotive and other fields. Studies have shown that the pore size is too large, will result in the quality of the products, how to control the pore morphology in order to ensure the quality of injection products is one of the research in the field direction. In this paper, from the molding process perspective process parameters the microporous morphology as well as the quality of the final product. In this paper, on the basis of the classical nucleation theory, consider the supercritical gas polymer melt * Free Energy, the polymer melt and supercritical gas binary system model, according to the unit molar system quality conservation, as well as The thermodynamic chemical potential of a calculation model, establish the mathematical model of the free energy change of the polymer melt; also consider the difference between the surface energy of the surface of the polymer and supercritical gas two-phase with pure polymer, the use of the weight of the gas mixing lysosomal * Score, create a model of the surface of the mixture can be calculated. Amendment through both the classical nucleation theory, the new microcellular foam injection molding nucleation theory model, the model is applied foam system, the relationship between the nucleation rate and saturation pressure and melt temperature, saturation pressure and melt temperature on the nucleation density. Comparison of simulation results with experimental data to prove that the nucleation process, which are predicted based on the new model with Colton and Kumar experimental results have a good agreement, Colton and Kumar experimental results with the classical nucleation theory does not match the problem solved theoretically , indicating that the new model than the classical nucleation theory model more accurate reflection of the entire nucleation process. Summary of previous classic microporous grow larger the basis of the theory of porous morphology difference with the actual results, combined with the numerical simulation technology, new nucleation model as the model grew up, grew up on the classic microporous model the correction; diffusion rate, melt viscosity, surface tension, and the nature of the polymer and gas from the start, single dissolves the physical properties of the model, in order to establish the physical parameters of the single compatibility database. Based on these two studies, a new microporous grew up model, and flat parts, for example, the process parameters of the melt temperature, the amount of pre-filled, injection time, cooling time, supercritical gas content of the pore size the impact of the trend. Based on the proposed microporous nucleation and growth theory, using a combination of methods of numerical simulation and Taguchi experimental techniques, signal-to-noise ratio analysis and analysis of variance on the experimental results, the relevant process parameters on the pore size proportion, to avoid the process of microcellular foam injection molding parts defects adjustment programs. On this basis, the use of multiple regression analysis method, take full account of the interaction between the process parameters on the basis of the establishment of the main process parameters impact on the pore size of the relational model, and as the objective function of optimization, simulated annealing optimization method, the dynamic relationship of numerical simulation and optimization methods, to optimize the molding process parameters and optimize the results are applied to the flat-panel model, get better results, ensure accurate microcellular foam injection molding process parameters set and scientific. We established a process parameter design system model based on numerical simulation technology. The proposed microporous nucleation and growth theory, numerical simulation, the Taguchi experimental techniques, multiple regression and optimization techniques organic integration into the design of the system, and on its basis, the use of VB programming, the establishment of a sets of complete microcellular foam injection molding machine process parameters design software systems. The establishment of the system so that the proposed theory, process optimization design production actually become possible. Microcellular foam injection molding process planning system applied to the actual production of complex parts, this study process design and software system design optimization of process parameters on the actual complex parts, the process parameters applied to actual production, so that the amount of deformation of the product is reduced from 1.8mm to 0.3mm or less, thereby improving the quality of products and to meet the design requirements of the product. This shows that the theory and methods discussed in this paper is correct and effective, and has a guiding role in the actual production.
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