In recent years, demands for automating machine tools and improving performance of the machine tools have been increasing more and more. To achieve the automation, automatic changer devices have been suggested, including an automatic tool changer (ATC) for automatically changing tools and an automatic pallet changer (APC) for automatically changing pallets on which a workpiece is placed. Further, peripheral devices including work feeding devices, such as a loader and a bar feeder, have been well known. Meanwhile, to achieve the improvement in performance, in-machine measurement using sensors and intellectualization have been implemented.
Further, in a part of the field related to machine tools, use of a robot has been suggested for automating the machine tools and further improving performance of the machine tools. For example, JP 2010-036285 A (hereinafter referred to as Patent Document 1) discloses a technique for loading and unloading a workpiece to a machine tool by means of a robot installed outside the machine tool. Further, J P 2010-064158 A (hereinafter referred to as Patent Document 2) discloses a technique in which an articulated robot is installed so as to travel on a gantry rail attached to an upper part of a machine tool, and transfer of workpieces through multiple machine tools is performed by the articulated robot. Still further, JP 2014-240111 A (hereinafter referred to as Patent Document 3) discloses a configuration in which a robot having a plurality of joints rotatable around a vertical axis is installed on a top surface of a machining device.