| 摘要 |
PURPOSE:To accurately and simply perform the switching of a plurality of feed pitches by providing a rotating driving shaft at one of two members capable of relative moving and providing a plurality of friction rollers slantly arranged on the circumference of the respective above driving shafts, rotatably and at different lead angles each other. CONSTITUTION:Voltage is added to a piezoelectric element by an operating device to lower a holding body 21 by its displacement so as to press a friction roller 23 on the circumference of a driving shaft. The driving shaft is rotated, the roller 23 follows the rotation of the driving shaft to roll on the circumference to move in the axial direction of the driving shaft by a feed pitch according to a lead angle A1 for transferring a table 20 to a bed 10 at a high speed. In the meantime, when the table 20 is reached close to an aimed position, the motor 15 is stopped, the added voltage is switched from the piezoelectric element 25 to 26 to separate the roller 23 from the drive shaft and the holding body 22 is lowered to press a friction roller 24 to the driving shaft. Hereupon, the driving shaft is rerotated to accurately move the roller 24 in the axial direction of the driving shaft by a feed pitch according to a lead angle A2. |
