Online measurement of the radial workpiece displacement in electromagnetic forming subsequent to hot aluminum extrusion

Abstract

Electromagnetic compression was integrated into the process chain of hot metal extrusion in order to reduce the cross section of the workpiece locally. To integrate both processes, a tool coil for electro-magnetic compression is positioned behind the die exit and coaxially to the extrudate. Additionally, a counter die in the shape of a mandrel can be mounted to the mandrel of a porthole extrusion die, which extends into the working area of the tool coil. Experiments were conducted on hollow profiles which were compressed by electromagnetic forming subsequent to extrusion. Due to an extremely short processing time of the high speed forming process, a compensation of the relative speed between the workpiece and the tooling can be ignored. For determine the workpiece displacement during the electromagnetic forming process, a new measuring strategy based on the Photon Doppler Velocimetry was developed.