A control device has a master shaft control unit that controls rotation of a master shaft, a slave shaft control unit that controls feeding of a slave shaft, and a numerical value control unit including a master shaft command unit that outputs a first inversion command to the master shaft control unit, a slave shaft command unit that, based on feedback information from the master shaft, outputs a second inversion command that follows the feedback information to the slave shaft control unit, and a prior inversion command unit that outputs a prior inversion command to the slave shaft control unit prior to the output of the first inversion command.

The invention relates to methods for producing a thread with a predetermined thread pitch in a workpiece.

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 from a starting position; a maximum-acceleration detecting section for detecting a maximum acceleration of the spindle axis during acceleration; 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; and a torque-command limiting section for limiting a fluctuation of a torque command of the position control, instructed to the spindle axis, to a predetermined range over a period until a predetermined elapse condition is satisfied after reaching the intermediate speed.

Provided is a method for identifying a disturbance component, including: when a vibration frequency included in a position deviation or a synchronization error between a tool axis and a workpiece axis is defined as fd, and a sampling frequency of a sampling period, which is a time from when a tool cuts a single tooth trace on a workpiece until the tool again cuts the same tooth trace, is defined as Fs, determining a frequency Fa of undulation in a tooth trace direction from a formula:
Fa=MIN|fd−N×Fs|, where N is a natural number, calculating a pitch of undulation in the tooth trace direction using the formula and a speed of the tool axis in a feed direction; and when the calculated pitch and a measured value of the pitch match, determining that fd is the disturbance component.

Provided is a method for identifying a disturbance component, including: when a vibration frequency included in a position deviation or a synchronization error between a tool axis and a workpiece axis is defined as fd, and a sampling frequency of a sampling period, which is a time from when a tool cuts a single tooth trace on a workpiece until the tool again cuts the same tooth trace, is defined as Fs, determining a frequency Fa of undulation in a tooth trace direction from a formula:

Fa=MIN|fdNFs|,

where N is a natural number,

calculating a pitch of undulation in the tooth trace direction using the formula and a speed of the tool axis in a feed direction; and when the calculated pitch and a measured value of the pitch match, determining that fd is the disturbance component.

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 from a starting position; a maximum-acceleration detecting section for detecting a maximum acceleration of the spindle axis during acceleration; 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; and a torque-command limiting section for limiting a fluctuation of a torque command of the position control, instructed to the spindle axis, to a predetermined range over a period until a predetermined elapse condition is satisfied after reaching the intermediate speed.

The invention relates to methods for producing a thread with a predetermined thread pitch in a workpiece.