| 摘要 |
In a method for manufacturing yokes (3, FIG. 1) to be used in a permanent magnet type stepping motor (10, FIG. 2), a surface-treated dead soft steel sheet such as nickel-plated steel sheet or aluminized steel sheet containing carbon in 0.01 wt. % or less is press-worked to form yoke (3) having plural pole teeth (3a, FIG. 1) on its inner periphery, and then the yoke is annealed in an inactive gas atmosphere in a temperature range of 750 DEG -820 DEG C. to remove residual stress, and permeability of the yoke is improved.
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