Coupled thermal-structural modelling and experimental validation of spiral mandrel die
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ORIGINAL ARTICLE
Coupled thermal-structural modelling and experimental validation of spiral mandrel die Yi Nie 1 & Ian Michael Cameron 1 & Johann Sienz 1 & Yueh-Jaw Lin 2 & Wei Sun 3 Received: 6 May 2020 / Accepted: 25 September 2020 # The Author(s) 2020
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. Keywords Spiral mandrel die . Coupled thermal-structural modelling . Finite element simulation . Pipe extrusion
1 Introduction The spiral mandrel die is a type of extrusion die that enables mass production of tubular polymer products such as tubes, pipes and blown films. It analysed and reported that one advantage of spiral mandrel dies lies in that they can render a uniform thickness, velocity and temperature distribution of the polymer melts upon exit [1]. The other is that it reduces the appearance of weld lines on the extruded products compared with the traditional spider-type extrusion die. In the extrusion process, complicated and severe thermal load and high pressure normally expose on the die assembly
* Yi Nie [email protected] 1
Advanced Sustainable Manufacturing Technologies (ASTUTE 2020), Swansea University, Swansea SA1 8EN, UK
2
College of Engineering and Engineering Technology, Northern Illinois University, DeKalb, IL 60115, USA
3
Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, Nottingham NG7 2RD, UK
[2]. A high level of temperature gradient or internal pressure directly affects die wear, tool damage and failure as well as deformation of flow channel which altogether result in shorter tool life and poor extrusion accuracy. This is especially true for spiral mandrel dies, which have complex geometrical features such as distributors and spiral grooves [3]. A thorough un
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