Metal Heating with the Homopolar Generator

The use of homopolar generators operated in the pulse mode to provide the heat necessary to accomplish resistance welds in large metal sections and to heat forging billets offers several possible advantages over present welding and heating methods. Welds having no fusion zones can be produced in a matter of seconds without the use of shielding gases or other welding consumables and while making only a modest and continuous power demand. When used to heat forging billets, pulse power from homopolar generators offers some unique possibilities. Because heating is uniform throughout the entire cross section, billets can safely be heated to forging temperature in comparatively short times, thus minimizing scale formation. Because energy is stored in the generator, the demand on the utility mains is low and essentially uniform. In this paper, the range of billet sizes and shapes that can be heated using a 75-MJ power supply are calculated. The power supply consists of six pairs of homopolar generators that can be configured in series, in parallel, or in any of several series-parallel combinations depending on the load requirements.