Simulation And Analysis Of Flow Field In Spiral Mandrel Blown-Film Die

With the development of the national economy, the demand of plastic film is constantly increasing. Spiral mandrel blown-film die is advanced and widely used in film blowing which is one of the most popular processing for plastics film. In this study, the flow field in the spiral mandrel blown-film die had been simulated and analyzed in order to improve processing property of molding.In this study, the mathematical, physical and finite element models were built. By using the CFD software, POLYFLOW, the flow field in spiral mandrel blown-film die was simulated and analyzed, and the profiles of pressure, velocity and shear-rate were obtained.According to the analysis of the particle tracks in flow, after crossing axially over the flight gap and then getting into the next channel, material will move circumferentially together with the material in the channel, then continue axial movement in the next fight gap. The material will move in this way until getting out the spiral zone, which is different with the aforehand point. Moreover, in this study, the concept of circumferential angle of axial flow was defined, which was regard as a key variable of mixing property for the die.The influence of the geometric parameters such as the taper of the spiral mandrel, the angle of decreasing channel depth, the lead angle and the spiral channel depth on the flow of the material in the spiral die was investigated through the analysis of the orthogonal experiment. Then based on the rules of good mixing performance and uniformity of material in the outlet of the. die, the geometry parameters were optimized.In addition, the influence of the material parameters and the flow rate on the pressure profile, the velocity profile and the uniformity of material in the outlet of the die was analyzed and discussed as well.Generally, with the simulation and the analysis, some conclusions which have guiding significance on production practice were drawn.