Effects Of Pressure's Changing In Extrusion Blow Molding On Wall Thickness Of Hollow Industrial Workpieces

Extrusion blow molding are widely used in the molding of various hollow containers and many complex workpieces, because of its characteristics such as lower production cost , more superior in forming performance and stronger in adaptability. However, the problem of wall thickness nonuniformity, which is common in the extrusion blow molding products and affected the quality of products and the service performance seriously, has become the biggest bottleneck that restrict the development of extrusion blow molding.The thesis by taking an hollow industry workpieces, a plastic oil tank as the main research object, Analysised influence of the Pressure on the thickness of workpiece, to improve uniformity of the hollow workpiece thickness optimization Scheme by changing the pressure conditions.Firstly, through the research and study on fluid type and rheological properties of polymer, for POLYFLOW fluid numerical simulations provide the theoretical basis.Secondly, numerical simulation by POLYFLOW software to analyze preform deformation of the process of parison inflation and thickness and predict the distributions of final part wall thickness, proposed and demonstrated the feasibility of part-vacuumizing blow molding technics and provided guidance for the optimization of the mold.Thirdly, the effects of the size of blow pressure, time of blow pressure and place of blow pressure on the three factor were proposed, orthogonal experiment design is established with three levels and three factors. Using variance instead of workpiece thickness uniformity as the index, Through analysis of experimental data determines optimum scheme: size of blow pressures0.3~0.5Mpa, time of blow pressure10~15s, position of blow pressure in the depth of oil tank workpieces 40mm.Fourthly, Through vacuum absorption technology (vacuum) and extrusion blow molding interaction, analysised distribution of workpiece thickness, and the best effect vacuum.was obtained, which was the advance time of parison inflation was 7s. Optimize uniformity of wall thickness of hollow industry workpieces great effect is verified by part-vacuumizing, and proposed an optimized distribution of wall thickness of hollow industry workpieces effective measures. The research of this paper combine CAE analyse and optimizing die design setting, which is validated by practice and have valuable impact. Through part-vacuumizing blow molding technology, increased the uniformity of wall thickness of hollow industry workpieces greatly, offered an effective measure to optimize the thickness of hollow industry workpieces.