| 摘要 |
PURPOSE:To enable a high accurate fine feed to be attained by providing the first table relatively movably provided for a base by the first ball screw thread mechanism and the second table relatively movably provided for the first table by the second ball screw thread mechanism. CONSTITUTION:The first table 23 moves for a base 10 by the first ball screw thread mechanism (threaded shaft 21, ball nut 22 and the first table 23), and the second table 43 moves relatively for the first table 23 by the second ball screw thread mechanism (threaded shaft 41, ball nut 42 and the second table 43). Here the second table 43 generates its final moving distance for the base 10 by adding the relative moving distance of the second table 43 to or subtracting it from the moving distance of the first table 23. Accordingly, the table enables its movement from a very fine feed (for instance, 0.1mum) to a quick feed to be obtained by adequately setting a difference of lead between the threaded shaft 21 and 41 in both the ball screw thread mechanisms. |
