A position compensation system of a tool changer includes a storage unit for storing a coordinate indicating a reference position of a turret, a rotary position coordinate detector for detecting the rotary position coordinate of the turret, a compensation necessity determiner for determining whether or not it is necessary to perform a rotational compensation to return the turret to the reference position, in accordance with a rotational deviation of the detected rotary position coordinate from the stored rotary position coordinate, and a compensation request part for requesting an operation or work related to the rotational compensation when it is determined that the rotational compensation needs to be performed.

An automatic tool changer includes first and second tool change units that is driven respectively by a pair of servo motors and move along an arrangement direction of a plurality of tools installed on a tool installation unit, a torque detection unit that detects a torque of each of the pair of servo motors, and a control device that controls operations of the first and second tool change units. The control device fixes the first tool change unit at a reference position, and moves the second tool change unit toward the first tool change unit. The control device determines, based on a torque change of each servo motor, that a plurality of upper tools are brought together at the first tool change unit as a result of a movement of the second tool change unit.

A machine tool for processing a workpiece comprises a processing station which has a tool receiving member in which a processing tool for processing the workpiece can be introduced and replaced, a tool store which has at least one storage space for a processing tool, a tool handling device which can be moved by a controlled drive into a tool-transfer position, a movement unit which can move the workpiece and the tool store and which can be moved by a controlled drive into any of a setup position, a processing position, and a tool changing position, a control device for the drive of the tool handling device which can define the tool-transfer position of the tool handling device, and a control device for the drive of the movement unit which can define the setup position, the processing position, and the tool changing position of the movement unit.

A machine tool (1) includes a tool information storage (9) storing therein used tool information for, when an NC program execution part (5) executes an NC program, specifying a tool used for machining, and a magazine operation panel (18) includes an announcement part (18b) for announcing an alarm to an operator. When receiving an operation signal from an input part (18a) while the NC program execution part (5) is executing an NC program, a tool change control part (11) checks the used tool information stored in the tool information storage (9), and in the case where a tool held by a tool pot (17a) corresponding to the operation signal is not used for machining, moves the tool pot (17a) to a tool attachment/detachment position (17c), and in the case where the tool is used for machining, causes the announcement part (18a) to announce an alarm indicating that it is unavailable.