An apparatus for detecting the status of a tool in a machine tool may include: a sensor unit configured to sense acceleration of a spindle of the machine tool in an x-axis direction and a y-axis direction during processing; and a processing device configured to convert the x-axis signal and the y-axis signal, sensed by the sensor unit, into signals capable of representing a cutting force by processing the x-axis and y-axis signals, detect a resultant force, and plot the detected resultant force on a polar coordinate system.

A tool magazine (40) is able to move among a machining position where a tool (2) attached to a spindle (30) machines a workpiece, a tool exchange position where the tool (2) attached to the spindle (30) is exchanged, and a retreat position where an automated workpiece carrying device is not disturbed in placing or removing of the workpiece with respect to a workpiece placing part (20). The workpiece is placed on the workpiece placing part (20) from above or removed upward from the workpiece placing part (20) by the automated workpiece carrying device.

In this motion evaluation method, which uses a circular motion test to evaluate motion characteristics of a numerically controlled machine tool, a normal direction change rate of a trajectory is calculated from a circular motion trajectory, the normal direction change rate of the trajectory is displayed in polar coordinates, and the motion characteristics of the numerically controlled machine tool are evaluated.

A tool magazine (40) is able to move among a machining position where a tool (2) attached to a spindle (30) machines a workpiece, a tool exchange position where the tool (2) attached to the spindle (30) is exchanged, and a retreat position where an automated workpiece carrying device is not disturbed in placing or removing of the workpiece with respect to a workpiece placing part (20). The workpiece is placed on the workpiece placing part (20) from above or removed upward from the workpiece placing part (20) by the automated workpiece carrying device.

In a machine tool, a control device performs control on an axis member rotating device and a stage rotating device such that when part of a placement region RE in a stage is arranged in a position opposite a spindle cutter in a third direction, in a direction which is at least one of a first direction and a second direction and in which accuracy is required, a screw axis length from a connection portion of the screw axis member of a ball screw and an axis member rotating device to a nut portion is minimized and that the part of the placement region RE in the stage is moved to the position opposite the spindle cutter in the third direction.

An apparatus for detecting the status of a tool in a machine tool may include: a sensor unit configured to sense acceleration of a spindle of the machine tool in an x-axis direction and a y-axis direction during processing; and a processing device configured to convert the x-axis signal and the y-axis signal, sensed by the sensor unit, into signals capable of representing a cutting force by processing the x-axis and y-axis signals, detect a resultant force, and plot the detected resultant force on a polar coordinate system.