| 摘要 |
PURPOSE:To permit the prevention of the variation of the torque of a hysteresis brake with a simple constitution, by a method wherein the control of stop is constituted of an exciting current increasing section and an exciting current decreasing section. CONSTITUTION:During operation, a tension between a driving roller 2 and an unwinding unit 4 is determined by the braking force of a hysteresis brake 5. When a predetermined work is finished, a driving motor is stopped by a stopping command. In this case, the inertia of an unwinding unit 4 is larger compared with the same of the shaft of the driving roller 2, therefore, the stopping time of the unwinding unit 4 is lengthened and a winding material 3 can be loosened. In order to prevent it, an exciting current I1 during operation is increased to the exciting current I2 for stopping the motor to increase a braking force and prevent the loosening of the winding material. Then, the exciting current is decreased immediately before stopping to the exciting current, equivalent to the exciting current I4 after the re-starting of the operation, or the exciting current I3 lower than the exciting current I4.
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