Purposive Design of a Magnetic Sheet Metal Forming Facility

This paper is about the identification of lumped elements within an electric circuit diagram in the context of electromagnetic sheet metal forming. Based on fundamental physical considerations the forming coil and its workpiece can be modeled as a transformer, which is loaded on its secondary side by a resistor. A systematic oriented design process relating to an aimed at purpose is introduced in order to avoid time extensive trial-anderror methods. Based upon the theory of electromagnetic field equations, the complex impedance of the sheet metal is analytically identified as a function of the radial component. Based on the introduction of a force equivalent quantity, ways of designing and optimizing the remaining free parameters are presented. Thus, a design process for a forming facility is possible as the desired electromagnetic force can be characterized by the currents running through the forming coil and the sheet metal

Assessing the Effective Energy for Magnetic Forming Processes by Means of Measurements and Numerical Calculation

The efficiency of magnetic sheet metal forming processes is strongly depending on the facility s overall design. This mainly includes the geometric layout of forming tool, work piece and matrix but, however, will also expect the energy storage device being taken into consideration. Apart from field theoretic models the energy storage is describable by its terminal traits which the electric load - tool coil and work piece - is connected to. The paper presents a measuring method for the tool coil s terminal quantities, current i(t) and voltage u(t), which are used to provide the electric power p(t) being transferred to the load. Thus, it is possible to determine the entire energy which is dissipated by the work piece, provided that the coil s resistance is known. Besides the measurement, this approach is supported by numerical calculation intending to take a closer look at the inner losses of the work piece which are not accessible from measuring the system s terminal traits directly. Dividable into separate parts of the total energy, this information is applied to assess the forming process by means of the facility s energetic performance and to draw an overall energy balance