Patent ID: 8347485

Claim:
A method for forming a cast shorted structure on the rotor of an induction motor, the rotor having a rotor rotation axis and comprising a plurality of generally planar ferrous laminations arranged to form a lamination stack, the lamination stack being generally cylindrical and having two ends and a cylindrical surface; the shorted structure comprising two end rings coaxial with the rotor rotation axis, one of each end rings abutting each end of the lamination stack and a plurality of conductor bars positioned proximate to the cylindrical surface of the lamination stack and connected on their ends to the end rings, the method comprising; applying a wax pattern of the shorted structure to the rotor; attaching at least one wax pattern of a sprue and runner structure to the wax shorted structure pattern to form an investment pattern; coating the investment pattern with a refractory coating to form an investment; removing the wax from the investment to create a sprue, a runner structure, a first mold end ring region, a second mold end ring region and a plurality of conductor bar mold regions; positioning the investment with the sprue positioned on and aligned with a casting rotation axis and with the rotor rotation axis inclined so as to be generally perpendicular to the casting rotation axis; filling the investment with molten casting metal through the sprue while rotating the investment about the casting rotation axis to urge outwardly radial flow of the casting metal from the sprue in a direction generally aligned with the rotor rotation axis, the molten metal first entering the runner, then the first mold end ring region, then along the conductor bar mold regions before entering the second mold end ring region; allowing the molten metal to solidify while the mold shell is continuing to rotate; and removing the gates and runners.