| 摘要 |
PURPOSE:To keep parallelism always and improve working accuracy by moving the right and the left ends of a cross rail independently in the vertical direction, detecting their height from a standard surface and controlling their vertical movement. CONSTITUTION:Scales 31, 32 are provided on the columns 3 at the right and left ends of a cross rail 6; readers 34, 35 move vertically with the cross rail 6 and read the amounts of its movement. The output of the reader 34 and that of the reader 35 are introduced into a control device 36, control independent servo motors respectively and always maintain the parallelism of the cross rail with respect to the upper face of a table accurately. To detect the amount of displacement a method of reading the movement of the Moire fringes of two optical lattices, a method to read magnetization patterns with magnetic heads, a method to read the change of induced voltage between two conductors, etc are applied. By so doing, the cross rail can be maintained parallel and highly accurate machining work can be carried out. |
