| 摘要 |
PROBLEM TO BE SOLVED: To provide a numerical control device for a machine tool capable of changing pre-loads and correcting the displacement of a spindle in the axial direction depending on a rotating speed. SOLUTION: The numerical control device for numerically controlling the movement of a spindle head 2 for operating pre-loads having different sizes depending on the rotating speed on bearings 36, 37 for rotatably supporting the spindle 5 comprises a numerical control part 6, a spindle control part 7 for controlling the rotation of the spindle 5 in accordance with a rotation command from the numerical control part, a pre-load changing control part 8 for changing the pre-loads on the bearings depending on the rotating speed in accordance with the rotation command from the numerical control part, and a correction processing part 9 for outputting to the numerical control parts 6 correction data a1-a13, b1-b8 for correcting the displacement of the spindle in the axial direction following the changed pre-loads and the displacement of the spindle in the axial direction depending on the rotating speed of the spindle in accordance with the rotation command from the numerical control part. Thus, the displacement of the spindle in the axial direction depending on the rotating speed of the spindle and the displacement of the spindle 5 in the axial direction following the changed pre-loads are corrected.
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