The Design And Theoretical Ansalysis Of An New Melt-Distribution Structure In Extrsion Die

Plastic extrusion die is an important part of extrusion equipment, which models extruded products. Melt-distribution structure is the pivotal part of extrusion die, which impacts on the quality of extruded products directly. Most melt-distribution structure of existing mainstream extrusion dies can not ensure the consistency of melt flow paths with simple structure. The others dies which can ensure the consistency of melt flow paths are difficult to design and manufacture and costly. And, the optimal design of the dies is almost focused on the design of melt-distribution.In this study, with the entry point of the consistency of melt flow paths, a new melt-distribution channel structure is designed. In this papers, directed against this melt-distribution structure, a blown-film die was designed. And the mathematical, physical and finite element models of the blown-film die were built. By using the CFD software, POLYFLOW, the flow field in the blown-film die was simulated and analyzed, and the profiles of pressure, velocity and shear-rate of flow field in the dies with different geometric parameters were obtained. According to the analysis of the flow field, geometric parameters, including the sectional area of distribution channel, the angle of the expansion part, the area ratio of the expansion part, the lateral structure of the expansion part, the length of calibrating segment and so on, were investigated through the analysis of the orthogonal experiment, and the optimized geometry parameters were obtained. In the study, the flow-rates in population was also discussed.The structure of the die with the melt-distribution structure designed in this study is simple and manufactured easily. It can achieve a good effect of melt distribution and flows in the non-dead flow path. And the pressure drop of the flow domain in the die is little, so the efficiency of the die is high. Such melt-distribution style and structure can also be used in tube dies, blown-film dies, sheet or film dies.Moreover, in terms of structural designing, manufacturing or the cost, it is very suitable for dies for compound triple-layer.