Advanced coil design for electromagnetic pulse technology : report on the methodology of coil design

摘要

Electromagnetic forming (EMF) is a relative new and attractive technology, which can be used for joining, welding, forming and cutting of metals. The technology is based on the utilisation of electromagnetic forces and offers attractive possibilities for:-obtaining a larger deformation of some materials, in comparison with conventional forming, while avoiding the disadvantages of the conventional processes,-fast and cost-effective joining of non-weldable materials, like heterogeneous joints;-creating complex or new workpieces and products, impossible by conventional technologies,-improving the working conditions of the welders or operator, since EMF is environmentally clean (no heat, fumes, shielding gases, radiation, etc.).The critical part of the technology is the coil, which is always application-specific designed. When inappropriately designed or constructed, these parts fail very quickly, or low process efficiency is obtained. Durable, robust and efficient coil systems are however essential for a successful implementation of EMF in industry.Currently, the knowledge concerning coil design is dispersed among the pulse machine manufactures, often confidential and thus not available for end users. One of the aims of the project is to develop all necessary knowledge to provide SMEs and other companies the flexibility to design and manufacture coils for specific applications. This will lead to an increased use and applicability of EMF in the metal processing industry.The technical targets aimed at in this project are:-Development of finite-element models, which will increase the knowledge about the process and which will serve as a tool in the coil design process.-Methodology for designing coils for forming and cutting of sheets and forming and welding of tubular workpieces.-Guidelines for manufacturing, material selection, insulation strategy and other construction-related aspects.-Manufacturing and testing of coil prototypes, for the development of industrial applications.-Providing the companies with all essential information to make a considered decision about the successful integration of the EMF and related technologies in their production.The final goal of the project was to enable companies to produce in a faster and a more efficient way by implementing EMF, which is currently hindered by the difficulties in designing the right coil. Due to an increased productivity and cost reduction by using this advanced technique, joining and forming operations will be performed faster and more efficient, so more economic, due to a less expensive production process and a better guarantee of the quality.The experimental research using pulsed-power equipment was performed by Fraunhofer IWU and the Belgian Welding Institute. EELAB of the Ghent University used its expertise in the field of calculation of magnetic forces, current density, etc. in order to calculate the desired shape of the coil systems. Finite-element modelling of the process was performed by the University of Chemnitz.