STAR MICRONICS CO., LTD.

A highly convenient machine tool system is provided. An NC lathe as an example of the machine tool system includes a first tool post to which a first tool for machining a workpiece is attached, a numerical control unit adapted to control a movement of the first tool post according to a numerical control program, and a scanner adapted to measure a position and a shape of the first tool attached to the first tool post brought to a predetermined position under control of the numerical control unit.

Provided is a machine tool and a method for controlling the machine tool capable of precisely determine a success or a failure of a cut-off. An NC lathe performs a cut-off of a workpiece gripped by a first spindle and a second spindle and then performs a separation movement of the second spindle in a direction separating from the first spindle. The NC lathe includes a movement controlling unit adapted to perform a stop control of the first spindle at a command position of the first spindle during the separation movement of the second spindle and a cut-off success or failure determining unit adapted to monitor a positional deviation of the first spindle during the separation movement of the second spindle to determine a success or a failure of the cut-off, the positional deviation being a difference between the command position and an actual position of the first spindle.

A machine tool capable of preventing production of a defective product. The processing unit determines whether the workpiece exists in the predetermined area. In the event that the workpiece exist in the area, the processing unit execute the top cut process. In the event that the workpiece does not exist in the area, the processing unit determines that the workpiece is in the abnormal position.

A machine tool improving measurement accuracy of a machined workpiece diameter. A machine tool comprises a displacement sensor mounted on at least one of a guide bush and a spindle supporting unit. The machine tool further comprises a calculating unit which calculates a diameter of the machined workpiece based on a measurement value of the machined workpiece by the displacement sensor. The spindle is movable back and forth in an axial direction. The spindle is retracted after machining to bring a machined portion of the workpiece to a predetermined measurement position in the axial direction to allow the displacement sensor to measure the machined portion.