Patent ID: 8014903

Claim:
A vibration suppressing device for a machine tool having a rotary shaft for suppressing a chatter vibration generated when the rotary shaft is rotated, the device comprising: a detection unit to detect time-domain vibration due to the rotating rotary shaft; a first calculation unit to calculate a frequency of chatter vibration and a frequency-domain vibration in the frequency of chatter vibration based on the time-domain vibration detected by the detection unit; a storage unit to store the frequency-domain vibration, the frequency of chatter vibration, and a rotation speed of the rotary shaft as machining information; a second calculation unit to store the frequency-domain vibration, the frequency of chatter vibration, and the rotation speed of the rotary shaft in the store unit as current machining information when the frequency-domain vibration calculated by the first calculation unit exceeds a predetermined threshold value, and to calculate an optimal rotation speed of the rotary shaft capable of suppressing the chatter vibration based on the current machining information and previous machining information stored in the storage unit; and a rotation speed control unit to rotate the rotary shaft at the optimal rotation speed calculated by the second calculation unit.