Abstract: In a method of working a recessed portion 2 in a headrest stay 32 which is provided in the stay portion 32 of the headrest stay 3 formed of a pipe, a recess 2? is preformed by pressing against the stay portion 32 an outer peripheral portion 4a of a first punch roller 4 for preforming having a rounded portion 47 on the outer peripheral portion 4a in a side view. Subsequently, an outer peripheral portion 7a of a second punch roller 7 on the outer periphery portion 7a of which a punch portion for final forming has been formed is directed toward and pressed against the recess 2?, so as to form a recessed portion 2.

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.

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.

Abstract: In a method of working a recessed portion 2 in a headrest stay 32 which is provided in the stay portion 32 of the headrest stay 3 formed of a pipe, a recess 2? is preformed by pressing against the stay portion 32 an outer peripheral portion 4a of a first punch roller 4 for preforming having a rounded portion 47 on the outer peripheral portion 4a in a side view. Subsequently, an outer peripheral portion 7a of a second punch roller 7 on the outer periphery portion 7a of which a punch portion for final forming has been formed is directed toward and pressed against the recess 2?, so as to form a recessed portion 2.

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.