A controller including: a positional deviation calculating unit that calculates positional deviation using a position command directed to a servo motor for driving a cutting tool, etc., and a position feedback value corresponding to the position of the cutting tool, etc.; an oscillation command calculating unit that calculates an oscillation command using the position command and a spindle axis angle of the rotated work, etc., or using the position feedback value and the spindle axis angle; an oscillation offset calculating unit that calculates an offset for the oscillation command using the positional deviation, the oscillation command, and the spindle axis angle; and a driving unit that determines a drive signal for the servo motor based on the positional deviation, the oscillation command, and the oscillation offset, and outputs the drive signal.

A method for reducing vibrations originating in a mechanical processing for removal of swarf comprising monitoring the vibration resulting from contact between the tool and workpiece, detecting the occurrence of a regenerative vibratory phenomenon, calculating the frequency of the phenomenon, estimating a value representing a resonance frequency of the machine as a function of the frequency of the phenomenon and determining a threshold value on the basis of the value. Also, comparing the operating speed of the mandrel with the threshold value and reducing the intensity of the phenomenon by a first reduction strategy based on correction of the operating speed of the mandrel being greater than the threshold value or by a second reduction strategy based on a continuous modulation which imparts an oscillation to the speed around the value of the operating speed, when the operating speed of the mandrel is less than the threshold value.

A vibration state detection device includes an imaging device configured to image at least one driven element to be driven by a drive unit of a machine tool; and a vibration state analysis unit configured to calculate a parameter corresponding to vibration of the driven element, based on image data for each predetermined period of elapsed time acquired by the imaging device. The parameter includes at least a vibration frequency and a machine tool including the vibration state detection device. Accordingly, it is possible to reliably obtain a parameter corresponding to vibration caused by cutting, even if cutting oil, chips, or the like adheres to a tool of a machine tool, and it is possible to suppress vibration caused by cutting.

Described is method for reducing vibrations originating in a mechanical processing for removal of swarf comprising monitoring the vibration which results from the contact between the tool (103) and a workpiece (WP) being processed, detecting the occurrence of a regenerative vibratory phenomenon, calculating the frequency of the vibratory phenomenon (f.sub.C), estimating a value representing a resonance frequency (f.sub.R) of the machine as a function of the frequency of the vibratory phenomenon (f.sub.C) and determining at least one threshold value (.sub.TR) on the basis of the value representing a resonance frequency (f.sub.R). The method also comprises comparing the operating speed (.sub.L) of the mandrel (102) with the threshold value (.sub.TR) and reducing the intensity of the vibratory phenomenon by the performance of a first reduction strategy (SST) based on a correction of the operating speed (.sub.L) when the operating speed (.sub.L) of the mandrel (102) is greater than the threshold value (.sub.TR) or by means of a second reduction strategy (SSV) based on a continuous modulation which imparts an oscillation to the speed around the value of the operating speed (.sub.L), when the operating speed (.sub.L) of the mandrel (102) is less than the threshold value (.sub.TR).

A vibration state detection device includes an imaging device configured to image at least one driven element to be driven by a drive unit of a machine tool; and a vibration state analysis unit configured to calculate a parameter corresponding to vibration of the driven element, based on image data for each predetermined period of elapsed time acquired by the imaging device. The parameter includes at least a vibration frequency and a machine tool including the vibration state detection device. Accordingly, it is possible to reliably obtain a parameter corresponding to vibration caused by cutting, even if cutting oil, chips, or the like adheres to a tool of a machine tool, and it is possible to suppress vibration caused by cutting.

A controller including: a positional deviation calculating unit that calculates positional deviation using a position command directed to a servo motor for driving a cutting tool, etc., and a position feedback value corresponding to the position of the cutting tool, etc.; an oscillation command calculating unit that calculates an oscillation command using the position command and a spindle axis angle of the rotated work, etc., or using the position feedback value and the spindle axis angle; an oscillation offset calculating unit that calculates an offset for the oscillation command using the positional deviation, the oscillation command, and the spindle axis angle; and a driving unit that determines a drive signal for the servo motor based on the positional deviation, the oscillation command, and the oscillation offset, and outputs the drive signal.

Provided is a machine tool with which the accuracy of a stop position of a drive subject can be improved in a case where semi-closed loop control is performed. The machine tool includes a guide mechanism for guiding at least one drive subject among the tool and the workpiece, a servo motor that moves the drive subject guided by the guide mechanism, and a control unit that performs semi-closed loop control on the servo motor so as to move the drive subject from an initial position to a target position. The control unit performs the semi-closed loop control so as to apply to movement of the drive subject a vibration component with which, from a midway position between the initial position and the target position to the target position, an advancing motion toward the target position and a retreating motion opposite to the advancing motion are performed repeatedly.

Provided is a machine tool with which a load acting on a drive system for driving a drive subject when the drive subject starts to move toward a target position can be reduced. The machine tool includes a guide mechanism for guiding at least one drive subject from among a tool and a workpiece, a servo motor that moves the drive subject guided by the guide mechanism, and a control unit that controls the servo motor so as to move the drive subject from an initial position to the target position. The control unit controls the servo motor so as to apply vibration in which an advancing motion toward the target position and a retreating motion opposite to the advancing motion are performed repeatedly to the drive subject for a set period up to a point at which the drive subject starts to move toward the target position from the initial position.