| 摘要 |
PROBLEM TO BE SOLVED: To appropriately set a torque command value to a servo motor when performing high-low pressure switching of a supporting thrust for pushing a center in a control for supporting a workpiece with a predetermined supporting thrust by using a driving torque of the servo motor in consideration of gear ratio of a driving system. SOLUTION: A normal operation torque command conversion part 21 obtains the torque command value Tx to the servo motor 9 by using a transmission efficiency in a normal operation (motion to convert the rotary motion to a linear motion of feed of the tailstock) of a feed screw of the tailstock. A reverse operation torque command conversion part 22 obtains the torque command value Ty to the servo motor 9 by using the transmission efficiency in the reverse operation (motion to convert the linear motion of the feed axis to the rotary motion of the screw) of the feed screw. A tailstock control part 51 controls the servo motor by making the torque command value Tx of the normal operation torque command conversion part 21 as a torque limit value when the supporting thrust for pushing the center is high pressure. When the supporting thrust for pushing the center is switched from the high pressure to the low pressure, the tailstock control part 51 controls the servo motor by making the torque command value Ty of the reverse operation torque command conversion part 22 as the torque limit value. COPYRIGHT: (C)2007,JPO&INPIT
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