Patent ID: 8256590

Claim:
A vibration suppressing device for suppressing vibrations generated during machining a work in a machine tool, comprising: a rotary shaft for rotating a tool or a work; detecting means to detect a time-domain vibration due to the rotating rotary shaft; calculating means to calculate a chatter frequency and a frequency-domain vibration at the chatter frequency on a basis of the time-domain vibration detected by the detecting means, to calculate phase information using the chatter frequency and number of tool blades of the machine tool, and calculate an optimum rotation speed of the rotary shaft for suppressing chatter vibration on a basis of the phase information when the calculated frequency-domain vibration exceeds a predetermined threshold value; and rotation speed controlling means to rotate the rotary shaft at the optimum rotation speed calculated by the calculating means, wherein the chatter vibration generated during the machining of the work by rotation of the rotary shaft is suppressed.