The present disclosure is directed toward a diagnostic method for a spindle arm of a machine. The method includes rotating the spindle arm of the machine at a first rotational speed, and acquiring, from an accelerometer, data indicative of a vibrational response of the spindle arm operating at the first rotational speed. The accelerometer is disposed along the spindle arm. The method further includes converting the vibrational response to a frequency based response to obtain a first frequency response, determining whether an amplitude of the first frequency response exceeds a diagnostic threshold, and performing a designated correction on the machine in response to the frequency response exceeding the diagnostic threshold.

A motor control device is a motor control device which controls a spindle motor of a machine tool, the device including: a low-pass filter which averages torque command values or drive current values of the spindle motor and calculates averaged load information of the spindle motor; and a time constant calculation unit which calculates, as a time constant of the low-pass filter, a first time constant based on a cut-off frequency according to the rotation number of the spindle driven by the spindle motor, or a second time constant based on a cut-off frequency according to a value produced by multiplying a of cutting tooth number of a tool by the rotation number of the spindle.

A control apparatus of a machine tool, the control apparatus including: a numerical control unit configured to create a spindle axis command and a feed axis command according to a tapping program; a spindle axis control unit configured to control rotational operation of the spindle axis according to the spindle axis command; a rotation detector configured to detect a rotation position of the spindle axis; and a feed axis control unit configured to control feeding operation of the feed axis according to the feed axis command on the basis of the rotation position. The numerical control unit is further configured to include, in the spindle axis command, a speed command value during return that does not depend on maximum rotation speed during machining of the spindle axis and that is higher than the maximum rotation speed during machining, as a command of return operation.

Provided is a control device for a machine tool capable of reducing adverse effects due to rapid changes in periodic fluctuations in the rotation speed of a main spindle while maintaining an effect of suppressing regenerative self-excited chatter vibration. This control device for a machine tool includes a fluctuation command calculation unit configured to calculate a fluctuation command based on a speed command for a main spindle motor of the machine tool and a fluctuation condition for causing a rotation speed of the main spindle motor to periodically fluctuate, and a speed control unit configured to control the rotation speed of the main spindle motor based on the speed command and the fluctuation command. The fluctuation command calculation unit is configured to calculate, when the fluctuation condition is changed, the fluctuation command in which an amplitude of the rotation speed that periodically fluctuates and/or a frequency of the rotation speed that periodically fluctuates gradually changes.

This control device includes an image display unit that displays, on a display screen, an operation image for changing an override value of a drive axis, a determination unit that determines the override value on the basis of an operation of the operation image, and a control unit that controls the drive axis on the basis of the override value determined by the determination unit.

A numerical controller for controlling a machine tool including a spindle motor formed of an induction motor includes: a storage unit that stores a maximum acceleration at which the spindle motor can operate when a magnetic flux amount of the spindle motor reaches its maximum; a magnetic flux amount acquisition unit that acquires a present magnetic flux amount of the spindle motor; and an acceleration change unit that changes an acceleration of a position command based on a maximum acceleration of the spindle motor stored in the storage unit according to a magnetic flux amount at the start of movement of the spindle motor acquired by the magnetic flux amount acquisition unit when the spindle motor is operated by position control using a position command.

Provided is a control device for a machine tool capable of stably achieving an effect of suppressing regenerative self-excited chatter vibration. This control device for a machine tool includes a fluctuation command calculation unit configured to calculate a fluctuation command based on a speed command for a main spindle motor of the machine tool and a fluctuation condition for causing a rotation speed of the main spindle motor to periodically fluctuate, and a speed control unit configured to control the rotation speed of the main spindle motor based on the speed command and the fluctuation command. The fluctuation command calculation unit is configured to calculate the fluctuation command by calculating a frequency of the rotation speed that periodically fluctuates of the main spindle motor based on the rotation speed of the main spindle motor based on the speed command and a frequency rate that is the fluctuation condition.

A numerical controller of the invention includes: an acceleration setting data storage unit for storing acceleration setting data where an acceleration/deceleration setting of an axis of a target machine to be controlled is associated with an application condition including at least a tool number; an execution acceleration/deceleration setting storage unit for storing the acceleration/deceleration setting used when a control of the axis is executed; an acceleration/deceleration control unit for performing an acceleration/deceleration control process on the axis on the basis of the acceleration/deceleration setting set in the execution acceleration/deceleration setting storage unit; and an acceleration/deceleration setting unit for setting the acceleration/deceleration setting of the acceleration setting data where a tool number commanded in a tool selection command of a block read from a machining program satisfies the application condition in the execution acceleration/deceleration setting storage unit.

A controller for controlling a synchronized operation of spindle and feed axes. A spindle-axis control section includes an initial-motion control section for accelerating a spindle axis at maximum capacity from a starting position; a maximum-acceleration detecting section for detecting a maximum acceleration of the spindle axis; a residual rotation-amount detecting section for detecting a residual rotation amount of the spindle axis; a current-speed detecting section for detecting a current speed of the spindle axis; a decelerating-motion control section for decelerating the spindle axis to reach an intermediate speed, after the acceleration; a positioning-motion control section for decelerating the spindle axis to reach the target position after reaching the intermediate speed; a flux-content predicting section for predicting an actual motor-flux content at the intermediate speed; and a deceleration determining section for determining a deceleration for a positioning operation, based on the maximum acceleration, the motor-flux-content command value and the motor-flux content.

A controller for controlling a synchronized operation of spindle and feed axes. A spindle-axis control section includes an initial-motion control section for making a spindle axis perform an accelerated rotation at maximum capacity from a process start position; a maximum-acceleration detecting section for detecting a maximum acceleration of the spindle axis; a residual rotation-amount detecting section for detecting a residual rotation amount of the spindle axis; a current-speed detecting section for detecting a current speed of the spindle axis; a positioning-motion control section for making the spindle axis perform a decelerated rotation so as to reach the target thread depth after the accelerated rotation; and an overshoot detecting section for detecting an overshoot of the spindle axis during the decelerated rotation.