Method of manufacturing a stator core

Abstract

A motor stator core for achieving improved magnetizing feature in lower magnetic fields and reduced iron loss, and improving motor power. The stator core fabriated out of non-oriented electrical steel sheets is annealed by applying a magnetic field to the heated stator core at least in the temperature range from a temperature immediately above a Curie point thereof to 300° C. in the process of cooling the stator core. The magnetic field has the same direction as the direction of exitation of a stator in the motor when used to drive a motor. This increases the magnetic induction in lower magnetic fields in particular and reduces the hysteresis loss, with a reduction in the total iron loss of the stator. A motor using this stator core increases in saturation induction under exciting currents of higher frequncies, allowing enhanced motor power.

1 . A stator core for use in a motor to be driven in a lower magnetic field of 1.0 T or less in magnetic induction, the stator core being made of non-oriented electrical steel sheets and annealed with a magnetic field applied thereto at least in a process of cooling from a temperature immediately above a Curie point thereof, said magnetic field having the same direction as that of excitation of a stator in the motor when used to drive the motor.