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Research on the Effect of Process Parameters of Microcellular Foam Injection Moulding on Cell Configuration

Author: ZhaoDongXiao
Tutor: WangZhaoYuan；HuGuangHong
School: Shanghai Jiaotong University
Course: Materials Processing Engineering
Keywords: Microcellular foam injection molding Nucleation theory Process parameters Taguchi Multiple regression
CLC: TQ320.662
Type: Master's thesis
Year: 2009
Downloads: 181
Quote: 4
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Abstract

With the rising price of plastic raw materials, plastic raw materials savings under the premise of ensuring product quality is one of the focus of current research. Microcellular foam molding methods have come into being, become a hot topic of current research. Micro-foam plastic cell diameter in the range of 5 to 100μm cell density of 109 ~ 1015 / cm3 foam. By carbon dioxide or nitrogen is injected into the polymer melt to form a single compatibility body, the thermodynamic instability of the use of the system to form a porous structure inside the plastic parts. Numerous studies show that the performance of the microporous injection molded parts mainly depends on the pore size and number of generated bubble nuclear morphology affect the final pore size and quantity of the basic factors. Therefore, the relationship between the the research process parameters and the foam nuclear morphology, obtained the model of the relationship between the actual production is essential. The paper aims to study nucleation of microcellular foam model, on this basis, with the help of the numerical simulation method to study the relationship between the molding process and the final size of the nucleation density and cell. Firstly, from the study classical nucleation theory principle to proceed, microcellular foam injection molding nucleation mechanism proposed classical nucleation theory with the actual nucleation process the differences that exist, that the main reason for these differences is due to the supercritical gas dissolved into the polymer melt, causing the polymer matrix of the free energy change in system free energy changes caused by these factors are not considered classic nucleation theory. Secondly, in the classical theory based on the analysis of the free energy change of the polymer matrix before and after the nucleation correction classic nucleation theory the free energy barrier of the formula to give improved theoretical models. And by PS/N2 foam system to verify the effectiveness of the improved model, indicating that the the improved nucleation theory model more realistic nucleation process. Then, the the improved nucleation theory model, combined with numerical simulation and Taguchi experimental methods to study the saturation pressure, melt temperature and gas concentration process parameters on the pore size, to draw various process parameters influence on the results of and weight, to provide theoretical guidance for the adjustment of the actual production process parameters. On this basis, the use of multiple regression, considering the influence of process parameters on the pore diameter, the establishment of a mathematical model of the process parameters and pore diameter. Regression model and a statistical analysis shows that the model can well reflect the relationship between the process parameters and the pore diameter. Finally, the application of research results to the actual production instance, thin-walled rectangular box as a case study, by the the Moldflow simulation experiment, injection pressure, injection molding cycle and warpage analyzed in three aspects microcellular foam injection molding method The difference between the traditional injection molding method, the results show that the microcellular foam injection molding can effectively shorten the injection molding cycle, lower injection pressure and clamping force and reduce warpage, improved product quality, meet the actual demand. These conclusions theory and method is correct and effective.

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CLC: > Industrial Technology > Chemical Industry > Synthetic resins and plastics industry > General issues > Production process and production technology > Forming > Injection molding
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