An Investigation On Rapid Heat Cycle Molding Technology

Rapid Heat Cycle Molding (RHCM) technology, developed from the high-precision product quality pursuit of customers, and for its precision, high efficiency, energy saving, environmental protection and other technical advantages to flourish. RHCM technology has already been in actual production well applied currently, and considerable success. Relative to production experience, the theoretical research is more scarce and hysteresis. In response to current research situation, this study has made a pioneering fundamental research work in process using experiment and numerical simulation methods. And the purpose is to give some theoretical guidance on high-gloss products, high-gloss mold design and development, and process determination and optimization etc.The numerical simulation technology of RHCM is studied. Based on the process characters of RHCM technology, suitable hypothesis and reduction are introduced. Considering melt filling and packing stages as uniform compressible process, the mathematical models of continuity, momentum and energy equation, have been derived based on the theory of polymer rheology theory, which is similar to Hele-Shaw model. And the corresponding boundary conditions are defined. The relation of melt viscosity with pressure changed is derived based on Rabino-Witsch equation, a viscosity correction factor is obtained. Thus a modified CrossWLF model is obtained, which can more objective description viscoelastic behaviors of polymer melt in filling process. Coupling with the Tait model to describe melt filling status, the numerical simulation of RHCM is realized ultimately.The high-gloss part, as well as the high-gloss mold, structure design technology is investigated, which can ensure products reaching to a high-precision replication with the cavity, and the temperature of mold cavity varied with the medium in timely and evenly. Then a vehicle-used high-gloss bluetooth mold, with following media path and straight through type media inlet, is independent innovated. And then a mold temperature control auxiliary system is introduced, especially the core devise of J11-W-160 type mold temperature control machine. The influence of temperature factor in Rapid Heat Cycle Molding on thermal stress maintained in part is researched. Based on continuity, momentum and energy equation, coupling with linear, infinitesimal, thermoelasticity Duhamel-Neumann equation, the relation between the thermal stress and temperature factor in cooling stage of RHCM is reached. Thus the influence tendency of temperature factor on residual thermal stress is analysis in theory.The influence of mold temperature on part quality is investigated, which is heated or cooled in the fast alternating conditions. The replication of part to cavity, shrinkage, wrapage and sink of part are considered as quality evaluation indexes. By integrating the experimental and numerical simulation method, as well as interference factors technology, this thesis investigates and come to the influence effect and impact law of mold temperature on product quality. It also studies and come to the influence effect and impact law of other parameters on product quality under fixed or changed mold temperature conditions, as well as the changing law of others with mold temperature under the same product quality presumed conditions. And the experimental results and the theoretical analysis are in good agreement.The RHCM process optimization technology is investigated. In this paper, the center composite design (CCD) method is employed in arranging the experimental points. And the samples qualitative data is processed to more objective response the products quality by integrating signal-to-noise (S/N) method, Entropy-Based Weight (EBW) method, Technique for Order Preference by Similarity Ideal Solution (TOPSIS), etc. Then a predictive response surface model (RS) for comprehensive quality index is created using Response Surface Methodology (RSM) based on analysis of variance (ANOVA) method. The RS model is interfaced with an effective improved Genetic Algorithm (IGA) to find the optimum process parameters values. And the actual production achieves good result, which shows that the process control technology is feasible and effective on processing quality optimization of high-gloss plastic part.