Machine tool and gear machining method

A machine tool comprising:

• a workpiece holder that is configured to rotatably hold a workpiece;
• a tool holder that is configured to be relatively movable with respect to the workpiece holder while rotatably holding one of a plurality of working tools configured to machine the workpiece, each tool of the plurality of working tools being configured to be attachable to and detachable from the tool holder, and the plurality of working tools including a hob cutter that is to be used in a rough machining of the workpiece and a skiving cutter that is to be used in a finish machining of the workpiece;
• a tool magazine that is configured to house the working tools;
• a tool replacing device that is configured to replace a first working tool, of the plurality of working tools, mounted on the tool holder with a second working tool, of the plurality of working tools, housed in the tool magazine;
• and
• a controller configured to
• operate the machine tool to perform the rough machining on the workpiece by relatively moving the workpiece and the hob cutter while synchronously rotating the workpiece and the hob cutter, the workpiece being held by the workpiece holder and the hob cutter being mounted on the tool holder;
• receive, from a tool measuring device, a measured position of a blade of the skiving cutter in a rotation direction of the skiving cutter in a finish machining preparation state, the finish machining preparation state being a state in which the workpiece holder and the tool holder are placed in a predetermined finish machining start position, and in which each of the workpiece and the skiving cutter is set at a predetermined rotation start angle;
• cause a correction, in the finish machining preparation state, of a rotation angle of the skiving cutter with respect to the workpiece based on the measured position measured by the tool measuring device, and cause a tooth space formed in the workpiece and an edge tip of the blade of the skiving cutter mounted on the tool holder to be placed in a position corresponding to each other;
• and
• cause relative movement of the workpiece and the skiving cutter while synchronously rotating the workpiece and the skiving cutter such that the workpiece is finish machined.