2016 年 82 巻 11 号 p. 970-975
On the precision positioning device of semi-closed control type which is driven by a ball screw, the expansion of the ball screw generates the positioning error of the stage during the stage repeated movement. The expansion is mainly caused by 2 heat sources of relative rotation of the ball screw/nut and angular ball bearings which support the thrust and radial force of the screw. In this study, the expansion measured by a gap sensor at the ball screw end is fed back to Peltier module to cool the screw/nut. Other Peltier modules cool both sides of housing made of pure cupper of large thermal conductivity to keep the housing temperature at the room temperature of 20℃. The angular bearings are cooled through the housing. At the same time, the datum point of minute displacement in the longitudinal direction of the device is corrected by the Peltier modules indirectly. As a result, the expansion of the ball screw in length of 400 mm is reduced from 18 µm under the repeated stage movement of 150 mm/s to 1 µm.