A motor control device is a motor control device which controls a spindle motor in a machine tool, and includes: a moving average filter which moving averages a torque command value or drive current value of the spindle motor for averaging time and generates averaged load information of the spindle motor; and an averaging time calculation unit which calculates, as the averaging time of the moving average filter, a first time of an integral multiple of a period of one rotation of the spindle driven by the spindle motor, or a second time of an integral multiple of a value arrived at by dividing the period of one rotation of the spindle by the number of cutting tooth of the tool.

A machine tool includes: a display; a tool configured to machine a workpiece; a spindle configured to rotate the tool or the workpiece; a sensor configured to detect a vibration frequency of the spindle or the tool; and a processor configured to control the machine tool. The processor is configured to: detect a chatter vibration in the spindle or the tool based on the vibration frequency; based on a frequency of the chatter vibration, a rotation speed of the spindle, and the number of cutting edges of the tool, calculate an order corresponding to the number of vibrations of the tool during a period of time until a current rotation angle of a first cutting edge of the tool reaches a current rotation angle of a second cutting edge of the tool; and present order information on the display, the order information indicating a magnitude of the calculated order.

A motor control device is a motor control device which controls a spindle motor in a machine tool, and includes: a moving average filter which moving averages a torque command value or drive current value of the spindle motor for averaging time and generates averaged load information of the spindle motor; and an averaging time calculation unit which calculates, as the averaging time of the moving average filter, a first time of an integral multiple of a period of one rotation of the spindle driven by the spindle motor, or a second time of an integral multiple of a value arrived at by dividing the period of one rotation of the spindle by the number of cutting tooth of the tool.

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.

A method of compact-form model-free adaptive disturbance compensation control in the presence of unmeasurable disturbances, includes establishing a dynamic data model of a controlled plant subject to unmeasurable disturbances, wherein the dynamic data model is described by a pseudo Jacobian input matrix and a pseudo Jacobian disturbance matrix; constructing cost functions and solving their optimization problems to find optimal values of the pseudo Jacobian input matrix and the pseudo Jacobian disturbance matrix; designing a compact-form model-free adaptive disturbance compensation control law in the presence of unmeasurable disturbances; constructing an energy function and solving it by using a momentum gradient descent method to find optimal values of the compact-form adaptive input matrix and the compact-form adaptive disturbance matrix; controlling the controlled plant by using the control law. The control method of the present invention provides significant improvements in disturbance compensation control performance and achieves effective tracking of desired system outputs.

A method of partial-form model-free adaptive disturbance compensation control in the presence of measurable disturbances, includes establishing a dynamic data model of a controlled plant subject to measurable disturbances, wherein the dynamic data model is described by a pseudo Jacobian input matrix and a pseudo Jacobian disturbance matrix; constructing cost functions and solving their optimization problems to find optimal values of the pseudo Jacobian input matrix and the pseudo Jacobian disturbance matrix; designing a partial-form model-free adaptive disturbance compensation control law in the presence of measurable disturbances; constructing an energy function and solving it by using a momentum gradient descent method to find optimal values of the partial-form adaptive input matrix and the partial-form adaptive disturbance matrix; controlling the controlled plant by using the control law. The control method of the present invention provides significant improvements in disturbance compensation control performance and achieves effective tracking of desired system outputs.

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 control method at least controls a spindle motor of a machine tool so as to perform machining in accordance with machining conditions. In the method, vibration occurring in a tool is acquired with a vibration acquisition unit, and the machining on a workpiece performed by a machining control unit is stopped when vibration having a predetermined amplitude or greater occurs in the tool. Based on state data indicating the state of the spindle motor at that time, multiple compensation plans for compensating the state of the spindle motor in order to suppress vibration occurring in the tool are calculated. The thus calculated multiple compensation plans are displayed on a display unit together with the state of the spindle motor at the time of occurrence of vibration having the predetermined amplitude or greater in the tool.

A chatter avoidance method and device is provided, including steps of: providing a stable operating condition plot; partially removing a first layer of a workpiece with a predetermined first removal depth according to a safe removal depth of the stable operating condition plot and sensing a chatter caused by the removal operation; if no chatter is sensed, completing the removal operation, otherwise, continuing to partially remove the first layer with a second removal depth less than the predetermined first removal depth; and determining a minimum removal depth according to the removal operation, and removing a last layer of the workpiece with a last removal depth less than or equal to the minimum removal depth, allowing the workpiece to have a target thickness. The disclosure prevents a chatter from continuously occurring without requiring a shut-down and thereby maintains a desired production rate.

A machining control device controls spindle rotational speed. A set of stability limit curve data is stored indicating a relation between a spindle rotational speed and a limit cutting-in amount whereby chatter vibrations are inhibited. Spindle rotational speed and tool cutting-in amount in starting machining are set based on the data. Vibrations of the spindle are detected during cutting. Whether chatter vibrations have occurred is determined based on vibrations detection. Spindle rotational speed is controlled with reference to the data to inhibit chatter vibrations. Cutting-in amount in starting machining is set to be less than a maximum cutting-in amount within a stable region of the data, and spindle rotational speed in starting machining is set to be less than a rotational speed when the cutting-in amount is maximum within the stable region. Spindle rotational speed is increased by an amount of a predetermined rotational speed when chatter vibrations have occurred.