Abstract: A tool changing unit moves between a magazine position and a changing position to transfer a tool. A machine tool has a plurality of tool changing positions. One of the tool changing positions is selected in advance for changing the tools next time. The tool changing unit and the tool mounted on a tool spindle move to the selected changing position for changing the tools in the selected changing position. Accordingly, the tool changing unit and the tool spindle move respective short distances for changing the tools, thereby shortening the non-machining time of a machine tool combined with the automatic tool changer.

Abstract: A machine tool consists in a pair of slide ways set apart one from another and extending parallel with a longitudinal axis, a machining station between the slide ways, presenting a first zone and a second zone adjacent one to the other, and a traveling gantry set in motion along the slide ways and carrying a machining head positionable in the first and second zones. Installed alongside at least one of the slide ways and containing a supply of tools attachable to the machining head is a magazine equipped with a first changer element positioned to coincide with the first zone of the station, and a second changer element positioned to coincide with the second zone, so that whichever of the two zones the machining head happens to occupy at any given moment, the tool currently in use can be replaced with a tool from the magazine by the relative changer element with minimal loss of time.

Abstract: A "safe" position for a tool changing operation in a numerically controlled machine tool is determined based on specific tool size and machining location. In one embodiment, tool change positions are taught in a teaching operation, and are stored for future reference. During machining, as each tool changing position is encountered, a pointer has advanced to the next such position so that, upon execution of the next tool changing command, the unit moves to the appropriate location. According to other embodiments, the machining program itself is made to store the tool changing positions. This data may be added to the program by an editor on the basis of the information found in the memory, or the data may be added in the initial creation of the program. The data on tool changing positions is then decoded from the machining program when the program is read or executed.