Determination of Plastic Material Properties of Thin Metal Sheets under Electromagnetic Forming Conditions

Abstract

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.

Impact of Die Coatings on Forming Conditions in Electromagnetic Embossing of Thin Sheet Metal

“…Optimization can be carried out with the aim of increasing the impulse Jy,w by applying substrate and coating with increased specific resistance ρ. This is opposed by an optimization of the plastic material behavior of the workpiece according to [18,22] which demands low specific resistance values. In addition to the electromagnetic influence, the individual mechanical properties and the influence on the process must also be considered.…”

An Application of a Magnetic Impulse for the Bending of Metal Sheet Specimens

“…To a minor extent, non-traditional methods are used in practice, which, in some cases, exceed conventional technical solutions. This phenomenon is also caused by the financial capabilities of manufacturing companies [ 12 , 13 , 14 , 15 , 16 ]. In the presented analysis in manufacturing companies, we came across this phenomenon, i.e., a lack of funds.…”