Design of Pulse Forming Systems for Pulsed Electromagnetic Manufacturing Applications

Electromagnetic (EM) manufacturing techniques are currently being used to manufacture several industrial components with both tubular and sheet metal workpieces. The deformation behavior of the workpiece in an EM manufacturing process is governed by the spatial distribution and the temporal behavior of the magnetic pressure acting on it. This article considers the specific inverse problem of pulsed power source design from the output objective temporal force waveform required for final mechanical deformation in the workpiece. It presents a novel method using direct transcription formulation to calculate the necessary input needed to generate the desired temporal variation in the magnetic pressure on the workpiece. The required controlling parameters for the rise time control, the peak pressure control, and the fall time control are identified. A model waveform has been proposed for the temporal variations of the EM force on the workpiece, followed by the technique to synthesize the tooling coil current using direct collocation methods. The suitable pulsed power circuit topology is then identified, and a curve fitting method is proposed to exactly achieve the desired temporal features of the force profile. Without loss of generality, the technique is experimentally validated for the free-forming process of sheet metal using a uniform pressure tooling coil (UPTC).