摘要 |
A system for correcting the position of a spindle of a processing machine, in which the spindle is rotatably mounted by hydrostatic bearings in a table on a bed and has an axial hole. A reflector is provided in the hole at a tip end portion, an interferometer is provided adjacent the other end of the spindle opposite the reflector, and a laser unit is provided for emitting a laser beam to the reflector and receiving the reflected laser beam through the interferometer and for producing an output signal dependent on the position of the tip end portion. The output signal is compared with a reference value and the spindle is shifted in accordance with the comparison so as to correct the displacement of the tip end of the spindle caused by thermal expansion. |