https://popups.uliege.be/esaform21/index.php?id=872 Publications of Auteurs Christian Schenck fr 0 https://popups.uliege.be/esaform21/index.php?id=4337 Electromagnetic embossing enables the transfer of surface structures from forming dies to metal sheets at high forming speeds. For this purpose, the contactless forming force is provided by means of a magnetic field of a tool coil which interacts with an eddy current in the workpiece. In thin sheets which are completely penetrated by the magnetic field, the resulting Lorentz forces act as body forces that accelerate the workpiece onto the forming die. In addition to the body forces, also high strain rates can support the embossing of thin sheets. This investigation deals with the embossing of pyramidal structures in the submillimeter range and an aspect ratio of about 1 into thin aluminum sheets (3.0255 / Al99,5). In order to quantify the reproduced microstructures, their extent is determined by means of a lateral analysis. From this, the replicated height is derived. Up to now it has been possible to partially reproduce microstructures with a large aspect ratio in thin sheets. In addition, the changing surface roughness of the sheets is taken into account. Before embossing, the sheets exhibit a relatively rough surface with a rolled texture, which is smoothed by the impulse forming with an optical forming die. This study reveals basic approaches for the electromagnetic embossing of optical microstructures. Thu, 01 Apr 2021 18:11:22 +0200 Thu, 01 Apr 2021 18:11:22 +0200 https://popups.uliege.be/esaform21/index.php?id=4337 https://popups.uliege.be/esaform21/index.php?id=2483 Compared to cutting processes such as milling, forming processes like electrohydraulic forming offer advantages regarding resource as well as energy efficiency. Due to high tooling costs, forming technologies are nonetheless considered as economically inefficient for low production quantities. Using a combination of high-speed forming with 3D printing technologies for tool manufacturing, three variants to reduce tooling time and costs for processing sheet metals for small quantities were proposed. Since the dies have to withstand high dynamic loads, 3D-printed low-cost dies made of polylactide (PLA) are limited regarding their form stability, mainly depending on the forming energy and sheet thickness. To enlarge the scope of application for 3D-printed dies a method to reinforce these dies is presented and investigated. Armoring of the dies was achieved by electrohydraulic cladding of the dies with 0.5 mm thick aluminum sheet metals. To characterize and compare the properties of the unarmored and the armored polylactide dies, specific characteristics of the formed sheet metals concerning the die wear and the molding quality were investigated. Polylactide dies enabled embossing of fine structures in addition to the forming of the die shape. Armoring of the dies led to a reduction of the embossed layer structure. Therefore, the armoring can be used as a way to control the characteristics of the formed sheet metals. In a further step, the cladding sheets were produced with copper sheet metals and used as sinking electrode for electric discharge machining of steel dies. Tue, 23 Mar 2021 20:21:45 +0100 Tue, 30 Mar 2021 09:37:17 +0200 https://popups.uliege.be/esaform21/index.php?id=2483 https://popups.uliege.be/esaform21/index.php?id=1464 During forming operations, the microstructure of metal parts is usually changed. Effects of cold hardening result in different mechanical properties, whereas the deformed microstructure also changes the electromechanical properties. The latter is responsible inter alia for the chemical corrosion behavior in terms of breakdown potential. In this study, the principle of corrosion resistance of steel E355 (EN 10305-1) was analyzed after rotary swaging with the same nominal strain but different process settings. Especially higher feed rates (forming increments per stroke) and the additional application of shear strain by eccentric rotary swaging increased the pitting potential significantly and thus the corrosion resistance. The introduced methods are assumed as prospective candidates for industrial production of parts that provide higher durability without further anti-corrosion treatment. Mon, 22 Mar 2021 19:56:49 +0100 Mon, 05 Apr 2021 17:57:02 +0200 https://popups.uliege.be/esaform21/index.php?id=1464 https://popups.uliege.be/esaform21/index.php?id=867 Electrohydraulic forming is a high-speed process, which is based on a force transmission by a working media. In this process, shock waves transmit the punching force in a very short period of time. These shock waves are applied to accelerate the workpiece towards a passive die. Besides forming and embossing of sheets and tubes, joining of sheets with tubes is enabled as a novel application presented in this contribution. Thereby, the tube is embedded temporarily in the die as a functional part. By accelerating the sheet towards the tube end, the joint is formed. This study deals with the question of how this joint is formed in sense of process kinematics and material flow. Therefore, the loading energy, the distance of sheet and tube as well as the sheet thickness was varied and the influence of these parameters and geometric conditions of the tube on the process and resulting joints was observed. Joining of EN AW-1050 aluminum alloy sheets to EN AW-6060 aluminum alloy tubes was performed. These joints were analyzed by microsections and head tension tests. The investigations introduce the new joining process regarding its process behavior and show first joining results. Sun, 21 Mar 2021 22:29:48 +0100 Mon, 29 Mar 2021 09:52:43 +0200 https://popups.uliege.be/esaform21/index.php?id=867 https://popups.uliege.be/esaform21/index.php?id=850 Electromagnetic forming is a contactless high-speed forming technique. In this process force transmission is initiated by an electromagnetic field provided by a tool coil. While forming thin sheet metal, the magnetic field is present in the whole depth of the sheet metal by definition. Thus, the magnetic field generates eddy currents in the complete sheet volume. The resulting Lorenz` forces act as body forces and are used for forming. Thereby high strain rates, high temperatures and multiaxial stress fields influence the plastic material properties of the workpiece. In this study, the plastic properties were investigated under real electromagnetic forming conditions. By varying process conditions like charge energy, sheet thickness and die material, the magnetic field and thus the plastic material properties were changed. To visualize the influence of the electromagnetic field, forming experiments were carried out. The strain of the formed sheets was measured. Furthermore, the forming forces were determined by measurements during the electromagnetic forming as well as by finite element simulations. With the measured strain and the determined forming force, a model for the plastic material behavior during electromagnetic forming was evolved. Sun, 21 Mar 2021 22:12:14 +0100 Fri, 02 Apr 2021 16:57:44 +0200 https://popups.uliege.be/esaform21/index.php?id=850