Analytical Design and Implementation of a Uniform Pressure Actuator for Electromagnetic Forming and Welding

Lightweight sheet metal components and assemblies formed and welded electromagnetically can be implemented in various industries such as automotive, aerospace, and electronics. Past applications and modeling of Electromagnetic Forming (EMF) and Magnetic Pulse Welding (MPW) have typically focused on crimping and expansion of tubular workpieces. While some Finite Element Analysis (FEA) packages exist that are capable of modeling these processes, there is a lack of simplified analytical modeling efforts, especially for sheet metal workpieces. Analytical modeling is attractive for its simplicity and cost in effectively determining e.g., an optimal coil design. In this paper a coil design and analysis procedure developed at The Ohio State University is modified and extended through an analytical model and FEA. The coil, named a Uniform Pressure Actuator (UPA), offers increased forming efficiency and repeatability, as well as a robust design. Coil design parameters such as the number of turns and conductor cross section are determined for a given workpiece. Magnetic pressure applied to the workpiece and workpiece velocity are predicted to ensure impact velocities are sufficient for MPW. A coil was constructed based on the analyses, and experimental results are compared to the analytical predictions for both electrical characteristics and workpiece velocity.