| 摘要 |
PURPOSE:To enable high-precise control of the position of a rotary shaft, by a method wherein a control magnetic field is exerted on a magnetic bearing in relation to the displacement of the rotary shaft, detected by means of a displacement detector to correct displacement. CONSTITUTION:An NC device 30 controls running of a motor to rotate a workpiece at the arbitrary number of revolutions. Further, the NC device controls the exciting currents of exciting coils 19A-19D according to a change in a magnetic resistance Rm due to a change in a gap (e) between a disc plate 14 and each of cores 17a-17d, detected by means of detecting coils 18a-18d of a deviation detector. Thus, control is effected so that the gap (e) between the disc 14 and each of the cores 17a-17d is uniformized. This constitution enables highprecise control of a position in relation with the rotation center of a rotary shaft.
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