Disclosed is a built-in type electric driving system of a machine tool. The system is capable of directly connecting a motor, which drives a spindle in a lathe which processes a workpiece, to an outer surface of the spindle without using a belt to rotate the spindle, and is capable of selectively transferring the power of the motor to a rotation system including a drawbar and a spindle for driving a chuck using a clutch device.

A motor control device according to an aspect of the present disclosure controls a motor by switching between speed control and position control, and sets a maximum voltage applied to the motor during the position control to lower than a maximum voltage applied to the motor during the speed control.

A spindle arrangement for a machine tool, comprising a spindle for driving a tool and at least one actuator for exciting vibration of the tool, characterized in that the spindle arrangement is provided with a compensation device for at least partly compensating the inertia forces produced by the vibration excitation in the spindle region.

Disclosed is a workpiece measurement method for determining the position of a workpiece on a machine tool based on feed shaft coordinates when a probe and the workpiece contact each other, in which the probe and the workpiece are moved relative to each other. The method includes the steps of moving one of the plurality of feed shafts to a desired measurement position, storing coordinate values of the one feed shaft at the desired measurement position, moving the probe and the workpiece relative to each other by means of the one feed shaft and another feed shaft, stopping the movement by the one feed shaft when the stored coordinate values have been reached, and measuring the workpiece at a plurality of measurement points by moving the probe using the other feed shaft in a state in which the one feed shaft is stopped at the coordinate values.

Disclosed is a built-in type electric driving system of a machine tool. The system is capable of directly connecting a motor, which drives a spindle in a lathe which processes a workpiece, to an outer surface of the spindle without using a belt to rotate the spindle, and is capable of selectively transferring the power of the motor to a rotation system including a drawbar and a spindle for driving a chuck using a clutch device.

A motor control device according to an aspect of the present disclosure controls a motor by switching between speed control and position control, and sets a maximum voltage applied to the motor during the position control to lower than a maximum voltage applied to the motor during the speed control.

A motor controller includes: a primary frequency control unit that generates a primary frequency command value based on current information of an induction motor and limits the primary frequency command value based on a maximum primary frequency; a rotation speed estimating unit that estimates a slip frequency based on the current information of the induction motor and estimates a rotation speed based on the estimated slip frequency estimation value and the primary frequency command value; a proximity switch that outputs an ON signal or OFF signal when a portion of a rotating body of the induction motor is in proximity or not in proximity; a rotation speed computing unit that computes a rotation speed based on the ON signal and the OFF signal; and a maximum primary frequency computing unit that computes the maximum primary frequency based on the rotation speed computation value.

A motor controller includes: a rotation speed estimating unit that estimates a rotation speed of a motor on the basis of current information and primary frequency information of the motor; a proximity switch that outputs an ON signal when a portion of a rotating body of the motor is in proximity and outputs an OFF signal when a portion of the rotating body of the motor is not in proximity; a rotation speed computing unit that computes a rotation speed of the motor on the basis of the ON signal and the OFF signal; and a state determining unit that determines whether a present state is a speed attainment state and whether a present state is a speed zero state on the basis of a rotation speed estimation value estimated by the rotation speed estimating unit and a rotation speed computation value computed by the rotation speed computing unit.

Disclosed is a workpiece measurement method for determining the position of a workpiece on a machine tool based on feed shaft coordinates when a probe and the workpiece contact each other, in which the probe and the workpiece are moved relative to each other. The method includes the steps of moving one of the plurality of feed shafts to a desired measurement position, storing coordinate values of the one feed shaft at the desired measurement position, moving the probe and the workpiece relative to each other by means of the one feed shaft and another feed shaft, stopping the movement by the one feed shaft when the stored coordinate values have been reached, and measuring the workpiece at a plurality of measurement points by moving the probe using the other feed shaft in a state in which the one feed shaft is stopped at the coordinate values.

To provide a numerical controller for a machine tool capable of reducing heat generation and realizing stable heavy cutting, and also capable of realizing efficient light cutting. A numerical controller comprises: first speed change means which changes the feed speed of a feed axis drive motor at the start of cutting to an initial speed lower than a command speed, based on magnetic flux content at the start of cutting; and second speed change means which changes the feed speed from the initial speed to the command speed continuously or intermittently based on time elapsed from the start of cutting and a time constant for change in the magnetic flux content.