| 摘要 |
PURPOSE:To make it possible to obtain a high speed response by providing a speed reduction unit between a hydraulic motor and a pinch roll, a bypass valve for allowing hydraulic oil to flow in parallel with the hydraulic motor and a torque applying means for applying a torque to the pinch roll in either the normal or reverse rotational direction of the hydraulic motor. CONSTITUTION:In order to allow a hydraulic motor drive unit to stably respond at a high speed, the natural angular frequency of the drive unit should be set to be higher than 63 rad/sec while the damping coefficient thereof should be set to be a large value in a range of 0.5 to 2.0. Accordingly, a speed reduction unit 14 is arranged between a hydraulic motor 6 and a pinch roller 4 so as to decrease the inertia moment while the natural frequency is increased. In order to eliminate a play caused by a backlash of the speed reduction unit 14, there is provided a torque motor 24 serving as a torque applying means. Further, in order to increase the damping coefficient, a bypass valve 20 is provided for the hydraulic motor 6 to increase the damping coefficient up to a value in a range from 0.5 to 2.0. With this arrangement, it is possible to obtain an optimum condition.
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