Coupled thermal-structural modelling and experimental validation of spiral mandrel die

Abstract

The conventional theoretical method to calculate deformations and stress states is only limited to a few cases of simple extrusion dies due to a number of assumptions and simplifications. A coupled thermal-structural modelling framework incorporating finite element method is thus developed and implemented to determine the mechanical performances of the complicated spiral mandrel die, which has a complex geometrical feature of spiral grooves and is exposed to severe conditions of thermal load and high pressure. The steady-state thermal analysis is carried out by mapping the temperature load on the flow channel from previously simulated flow characteristics of polymer melt. The structural analysis takes inputs from both thermal analysis and previously simulated pressure on polymer melt. Both the temperature and pressure loads on flow channel are transferred via the Smart Bucket Surface mapping algorithm. The mechanical properties of the spiral mandrel die are evaluated by analysing the deformation and stress distribution. The experimental validation is conducted to demonstrate the effectiveness of the numerical model. The effects of both structure parameters of the spiral mandrel and processing parameters upon the maximum stress in the die body and the maximum pressure induced deformation at the die orifice are investigated.

Improved Optimization of a Coextrusion Die with a Complex Geometry Using the Coupling Inverse Design Method

“…Compared with the traditional extrusion die design [ 40 , 41 , 42 ], the coextrusion die design is more complicated due to the coupling of the free surface and the coextrusion moving interface and the difference in the rheological properties of the materials. In the coextrusion process, the mechanism of the interfacial movement is relatively complicated, and it is generally believed that the existence of the pressure difference on the interface causes the interfacial movement.…”

A Novel Mandrel-Free Blown Film Die with Ultrashort Flow Distance and Uniform Discharge: Theoretical Modeling and Simulation

“…At the same time, as the melt flows around the fins or wing supports and reunites, these indispensable mandrel bracket will produce many weld seams in the die. The spiral die contains multiple small flow channels, which can avoid the problem of weld seams, − but complex and narrow multiple flow channels will greatly extend the residence time of melts in the die and aggravate the thermal decomposition of polymer melts…”