| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect the increase of a load of a main spindle due to the cutting failure and the margin failure by determining the generation of abnormality in a main spindle when the number of revolution of the main spindle below the lower limit of the number of revolution is detected. SOLUTION: Then a main spindle 1 is rotated by the main spindle rotating command, whether the number of revolution of the main spindle achieves the set number of revolution (command value) or not is determined. During the cutting, an abnormality detecting unit 21 compares a lower limit value of the number of revolution previously decided in response to the command value of the number of revolution of the main spindle and the feeding speed set by the working program of CNC with the number of revolution of the main spindle 1 detected by a speed detecting unit 23, and in the case where a real measured value is below the lower limit value of the number of revolution, abnormality of the main spindle is determined. When the abnormality of the main spindle is determined, the main spindle abnormality determination processing is performed. In the main spindle abnormality determination processing, a function such as a feeding stop function, a cycle stop function and a Z-axis retract function (main spindle retraction) can be selected with the M-code of the working program of CNC.
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