| 摘要 |
PURPOSE:To enable a mechanism to obtain high accuracy and high rigidity, by supplying a differential pressure to a static pressure pad and correcting a clearance by a detection signal of the clearance between the second table, driven by the static pressure coupling in a static pressure supporting part, and the first table straight advancing by a feed screw. CONSTITUTION:A table mechanism, introducing an electric signal of a displacement detector 14, 15 as an input signal to a differential amplifier 16 while an output signal of the differential amplifier 16 as a control signal to a servo valve 19 through a compensating circuit 17 and a servo-amplifier 18 and giving the pressure of fluid to a plurality of differential pressure relative static pressure pads 9f by the servo valve 19 in accordance with the control signal, is controlled so as to hold a clearance 12, 13 to a fixed value. While the mechanism, positively correcting the clearance and performing the position correction of motion in the second table in its feed direction, is controlled so as to increase coupling force in accordance with a load. Accordingly, the table mechanism of high linearity, in which an error of work and assembly or the like in a table guide surface and a feed screw is eliminated and a disturbance by deflection due to turning of the feed screw is prevented from being transmitted to the second table through a nut, can be obtained. |
