Analysis of Extrusion Processes of Magnesium-Alloy L-shaped Products and Circular Tubes
| Autor: | Chao-Chih Chang, 張兆志 |
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| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 The superior properties of magnesium-alloy draw attention from the light-trend industry recently. In this thesis, the finite element code, DEFORM, is employed to simulate the extrusion processes of L-shape solid profile and hollow tubes of AZ31 magnesium-alloy. The extrusion of L-shape solid profiles was examined first and the pocket die design was applied to the extrusion study. In the extrusion of the L-shape solid profiles, the unbalanced material flow that causes the extruded part being curved usually occurs. The finite element simulation results show that the unbalanced material flow is affected by the process parameters such as the location of L-shape profile, initial temperature, extrusion speed, friction factor (m), and pocket angle. And the pocket angle is found to be the major process parameter that causes the unbalanced material flow. The finite element analysis was performed to examine the effect of pocket angle on the material flow in details and an optimum pocket die design that renders a straight extruded part was determined. The actual extrusion experiments were conducted to validate the finite element analysis and the good agreement between the experimental data and the simulation results confirm the validity of the finite element analysis on the pocket die design. The extrusion of seamless AZ31 magnesium-alloy circular tubes was also studied in the present study with the use of the finite element analysis. The effects of the process parameters such as initial extrusion temperature, extrusion speed, and m value on the formability of the extruded circular tube were examined. The limited values of the process parameters that yield a temperature at the exit far below the ignition point of the magnesium-alloy were determined. The proposed design values for the process parameters could be used as design guidelines for the extrusion of AZ31 magnesium-alloy circular tubes. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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