Rotating shaft rotational speed of the machine tool monitoring method and a monitoring device, the machine

The present invention provides a monitoring method and monitoring device in a machine tool spindle rotational speed of the machine, irrespective of its speed shaft, can be displayed most suitable for suppressing high-frequency vibration period fluctuation, it is possible to easily set in a short time optimal parameters. When the rotation speed changes, indicating the relationship between the speed variation of FIG amplitude fluctuation (Q) and variation period (P) (20) displayed on the monitor (14), in FIG variation (20) in addition to display the current set value (a), but also shows the best PO period fluctuation amplitude fluctuation (Q) and variation period (P) may be set to a range (21), and according to the following formula (1) obtained and / or according to formula (2) optimum range variation period (P) of the obtained P1. T is the rotation period of the rotary shaft, a, amin, amax is a predetermined coefficient, PO = aT? ... (1); aminT≤P1≤amaxT ... (2).