Nisshin Steel Co., Ltd.

Fdk Corporation

Kazuyuki Watanabe

Hirofumi Nakano

Takayuki Matsui

Toshihiko Takemoto

Ryoji Hirota

Masakuni Kamiya

Akito Suzuki

Kazutaka Honma

In a stepping motor, stator yokes have a plurality of comb-tooth-shaped magnetic poles,and,in such a manner that the comb-tooth-shaped magnetic poles are opposed to each other coaxially to a rotor portion made from a permanent magnet magnetized to have multiple magnetic poles, and an excitation coil is fitted on the external circumference of the stator yokes and the excitation coil and the stator yokes are surrounded by a frame yoke. Each of the yokes is formed of an Fe&mdash;Cr alloy having a predetermined ferrite single-phase structure so that occurrence of eddy currents in an alternating-current magnetic field is suppressed.

Stepping motor with rust inhibiting and eddy current minimizing characteristics

There is provided a stator yoke capable of improving magnetic characteristics and a rust-proofing effect of a stator yoke produced by using a Fe-Cr type alloy. When a stator yoke is produced by using a Fe-Cr type alloy, its magnetic characteristics can be improved, but when press working is made to obtain a predetermined shape, the magnetic characteristics drop. Annealing is carried out so as to recover the magnetic characteristics. This annealing generates the property change of a surface layer and a rust-proofing effect lowers.

Stator yoke and method of producing same

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Hamamatsu, Japan

Kazuyuki Watanabe