Abstract: A method of manufacturing a magnetic rotor core member for a rotating-field dynamoelectric machine, particularly a small alternator, including the steps of hot forging a segment of steel bar stock into a core blank approximating the final volume desired for the rotor core member but with the pole piece finger angled outwardly from a central disc section at an angle of 45.degree. to 80.degree., the fingers being shorter than required for the finished pole pieces, de-burring the core blank and gradually cooling it. A shaft aperture is cold punched through the hub of the core blank, the pole piece fingers are bent into a vertical position relative to the rotor disc, and the pole piece fingers are ironed into close conformity with the required finished dimensions, in particular lengthening and shaping the fingers; this is all done in one step in a cold-forging press. The core blank is cold compressed to finished form as a rotor core member. Annealing is an optional step.

Abstract: A method of manufacturing a magnetic rotor core member for a rotating-field dynamomoelectric machine, particularly a small alternator, including the steps of: hot forging a segment of steel bar stock into a core blank approximating the external configuration desired for the rotor core member but with the pole piece fingers shorter than required for the finished pole pieces; de-burring the core blank; coining the core blank into closer conformation to the desired core member configuration; gradually cooling the core blank; rough machining only two opposed surfaces of the hub and base to assure a controlled uniform volume for subsequent processing; cold punching a shaft aperture through the hub of the core blank and simultaneously ironing the pole piece fingers into close conformity with the required finished dimensions, in particular lengthening the fingers; and, finally, cold-compressing the core blank to finished form as a rotor core member in a single cold compression step.

Abstract: A method of manufacture of a magnetic rotor core member for a rotating-field dynamoelectric machine, particularly a small alternator, including the steps of: hot forging a segment of steel bar stock into a core blank approximating the external configuration desired for the rotor core member; de-burring the core blank; coining the core blank into closer conformation to the desired core member configuration; cooling the core blank; cold punching a shaft aperture through the central part of the core blank and simultaneously cold-compressing the core blank into closer conformity with the required dimensions for the finished rotor (or rough machining of a shaft aperture and rough machining of some elements of the blank); and, finally, cold-compressing the core blank to finished form as a rotor core member.