Development and experimental investigations of a new die concept for hot extrusion of lightweight alloy hollow profiles with axial variable wall thickness, Part II

摘要

This publication deals with the development of an innovative porthole die for the extrusion of light metal alloy hollow profiles with axial variable wall thickness. In contrast to conventional rigid dies that only allow the extrusion of the same profile cross section along the profile length, the aim for the new die design was to add more versatility to extrusion tools and thus, to the extrusion process itself. The basic idea was to incorporate moveable segments to the porthole die in order to realize variations of the mandrel geometry during the extrusion. Initially, transient numerical simulations were conducted to analyze the metal flow of the workpiece during extrusion and to determine the load requirements necessary for wall thickness transitions. To investigate if the new innovative design of a porthole die would be able to withstand the loads during extrusion, a die stress analysis was carried out. After the development phase the die set was manufactured and put to test in extrusion experiments. The feasibility study showed that the die withstood the thermomechanical loads during extrusion and the profile wall thickness was varied successfully by up to ?t = 1.2 mm from t = 4.4 mm to t = 3.2 mm. Part I of the article was published in International ALUMINIUM Journal 9/2021, pp. 60-63.