Three-stage modeling, simulation and analysis of blow molding product processing technology


Author: MULAN -Plastic Molding Manufacturer

Three-stage modeling, simulation and analysis of blow molding product processing technology To become a valuable material, polymers must be processed and formed, so the development of polymer processing and forming technology determines the overall development level of polymer materials science and technology. Blow molding product processing technology is the third largest polymer molding technology, and it is a polymer molding technology that has developed rapidly recently. Compared with the widely used injection molding technology, the cost of blow molding equipment and molds is lower (for example, the mold cost of blow molding automobile bumpers and deflectors is about 1/4 of that of injection molding), and the clamping force is small (blow molding parison The inflation pressure is generally lower than 1MPa, while the melt pressure in the injection mold cavity is generally 15 ~ 140MPa), low energy consumption, strong adaptability (Complicated structure can be formed, double-walled production), the formed industrial parts have high integrity, good comprehensive performance, high added value, small defects, and low cost. Therefore, the processing technology of blow molding products has become more and more popular in the automotive industry and other fields. more and more widely used. Recently, blow molding industry accessories are developing in the direction of complexity and large-scale. However, there are prominent problems such as large material consumption, high processing energy consumption and low production efficiency in blow molding products of industrial parts such as automobiles. The structures of various connecting pipes and ventilation pipes in automobiles are complex, and most of them are three-dimensionally curved, and a large amount of flash will be generated during blow molding. For example, the flash quality of an automobile pipe fitting produced by an auto parts manufacturing company using conventional blow molding product processing technology is more than twice the quality of the fitting; of 9 times. In addition, blow molded parts with complex structures and large differences in wall thickness have problems such as low appearance performance and low molding pass rate. Blow molding product processing technology includes three stages: parison molding, parison inflation and product cooling, which directly affect the size and various properties of blow molding products, and are the main factors that determine the material and energy consumption of the blow molding process. 1. Parison forming The parison molding stage is mainly affected by two complex rheological phenomena, die expansion and drape, and their combined effect determines the size and shape of the parison before inflation. 1) Neural network model prediction of parison size. Based on a series of data obtained from experiments or finite element (FE) simulations, a neural network ( NN) model. Applying the NN method to the study of parison molding affected by multiple factors can determine the quantitative relationship between parison size and mechanical parameters, material performance parameters and blow molding product processing parameters, with no or minimal simplified assumptions, There is no need to use constitutive equations, online prediction, faster response, etc. using the established The predicted results of the NN model are in good agreement with the experimental results, which provides a theoretical basis for the on-line control of the parison size. 2) Simulation of the size of the parison under the variable head die gap. For each preset die gap, the FE method is used to carry out a simulation; the parison sub-sections obtained by simulation under each die gap can be combined to obtain the whole section extrusion under the change of the die gap. The parison profile and size distribution of the obtained blow molded products should be consistent with the experimental results. 2. Parison inflation The parison in the inflation stage is subject to large deformation and involves nonlinearity in geometry, material and contact, so its modeling and simulation are more difficult. Starting from the force balance of the micro-volume elements of the parison (thin shell), a physical model of the free inflation of the parison is established. Based on the thin film approximation and the neo-Hookean constitutive relation, a mathematical model describing the free inflation of the parison is derived. The mathematical model established above can be used to predict the local stretch ratio, axial and circumferential local stress distribution and wall thickness distribution when the parison is freely inflated, and can also predict the effect of free inflation of the parison on material properties and parison dimensions. and Dependence on processing parameters of blow molded products, etc. 3. Product cooling and solidification The cooling efficiency of blow molded products directly affects the productivity and energy consumption of blow molding, and is one of the main factors affecting the crystal structure formed in the product. A small change will lead to crystal growth and thus a large change in product performance. The three-dimensional temperature field, crystallization kinetics and Young's modulus of the blow molded product can be established in the cooling stage (E) Mathematical model. Through simulation, the transient temperature distribution in the wall of the blow molded product is predicted and compared with the experimental results, providing temperature data for further analysis of the microstructural properties (degree of orientation, crystallinity, density and residual thermal stress) and performance of the product. Proficient in blow molding|custom blow molding products.

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