Measuring method and device of machine accuracy in machine tool

A measuring device of a machine accuracy in a machine tool for measuring an accuracy of an angle of rotation of a tool post by detecting a reference sphere which is installed at a predetermined position by means of a touch probe installed to the rotatable tool post, the measuring device comprising:

• a first measuring means which detects a center position of said reference sphere at an angular range near a rotating movement starting point angle or the tool post according to a five-axis geometrical error measuring method;
• a second measuring means which detects the center position of said reference sphere according to the five-axis geometrical error measuring method by setting a plane including a first measurement axis which is orthogonal to a first measurement plane used in the first measuring means and one axis of the first measurement plane to a second measurement plane and setting an axis which is orthogonal to the second measurement plane to a second measurement axis;
• a switching means which switches from the first measuring means to the second measuring means at a predetermined angle position of the angle of rotation in said tool post;
• and
• a moving means for respectively moving the first measurement plane and the second measurement plane in directions of said first measurement axis and said second measurement axis in correspondence with a respective angle of inclination in the touch probe which detects the reference sphere.