Flow Simulation In Pipe Die And Parameters Analysis During High-Speed Extrusion

Extrusion is one of the most important plastic molding methods. As wide application and mass-production of plastic goods, plastic molding machines have been highly developed. Generally speaking, high speed and high efficiency are always extrusion technology' s developing trend.Although high speed and high output can make investor get more returns with little investment than before, seeing from technical aspect, the increase of screw revolution speed would lead to troubles in processing, we often find out that during the extrusion process, extrusion process under low speed is steady. However, when screw speed increases to a certain degree, unstable states of extrusion will occur. The realization of high speed extrusion not only relates to screw rotation, but also relates to extruder, assistant equipment, die, material parameters, and so on. In all, high speed extrusion is a complex system in which high speed and high quality are closely related from each other.On the basis of long time studies on the theories and mechanism ofunstable flow, in this paper, ANSYS is used to discover more about flow status in die during high speed extrusion, such as the field of flow velocity, pressure and wall shear stress; in order to make way for improving high speed extrusion stability and reducing energy wastage during extrusion, this paper has discussed the change of melt flow state when changing the length of separating segment, compressing segment and shaping segment under a certain process condition in a given high output.The main research works in this paper are as follows:1. A high pipe die model has been set up and simulated, then we conclude: as melt flow accelerates, flow velocity, pressure and wall shear stress rise almost by the same step as the increase of output ; because melt doesn't flow from compressing segment to shaping segment smoothly, flow velocity and wall shear stress in shaping segment always fluctuate in a axial distance;2. When changing the length of separating segment, the pipe die model was rebuilt and simulated again, then we find: as the increase of separating segment length, separator angle decreases, middle flow velocity' s sudden-break point moves from compressing segment to calibre segment, then melt' s recovery time after break will be longer;3. If the compressing segment increases, sudden-break point of middle velocity in die will move towards outlet, then melt' s recovery time will be...