Friction Stir Welding for Assembly of Copper Squirrel Cage Rotors for Electric Motors

摘要

The automotive industry is developing designs and manufacturing processes for new generations of electric motors intended for use in hybrid and electric vehicles. This paper focuses on solid-state welding to join copper end rings to copper spokes in the fabrication of copper rotors. Friction stir welding was explored to examine weldability of these copper components. Defect free welds were produced on 8-9.5 mm thick copper plates with copper spokes through slots at a travel speed of 225 mm/min and a tool speed rotation of 2250 rpm using lanthanated tungsten as the welding tool. The H13 and nimonic tool materials underperformed due to higher welding temperatures. The conditions were optimized by monitoring the tool and copper plate temperatures. Several tool geometries were investigated and the scrolled shoulder with tri-flat threaded pin performed the best. The strength and weld characteristics were sufficient for this application. Finally, this work puts forth major welding process for induction copper rotors.