Movement error identification method for machine tool

A method of identifying a relative motion error between a spindle for holding a tool and a table for mounting a workpiece thereon in a three-dimensional space in a machine tool, the machine tool including the spindle and the table and including a Z-axis feed mechanism, an X-axis feed mechanism, and a Y-axis feed mechanism respectively corresponding to a Z-axis, an X-axis, and a Y-axis as reference axes, the Z-axis extending along an axis of the spindle, the X-axis and the Y-axis being orthogonal to the Z-axis and orthogonal to each other, the machine tool being configured such that the spindle and the table are moved relative to each other in the three-dimensional space by the X-axis feed mechanism, the Y-axis feed mechanism, and the Z-axis feed mechanism, the method comprising:

• operating the X-axis feed mechanism, the Y-axis feed mechanism, and the Z-axis feed mechanism in a three-dimensional space of the machine tool coordinate system defined with respect to the machine tool at zero position X0, Y0, Z0 respectively set for the X-axis feed mechanism, the Y-axis feed mechanism, and the Z-axis feed mechanism, and measuring following errors with respect to an arbitrary coordinate position in the machine tool coordinate system:
• a positioning error in the X-axis direction;
• a positioning error in the Y-axis direction;
• a positioning error in the Z-axis direction;
• translational errors in the X-axis, the Y-axis, and the Z-axis;
• angular errors around the X-axis, the Y-axis, and the Z-axis in the X-axis;
• angular errors around the X-axis, the Y-axis, and the Z-axis in the Y-axis;
• angular errors around the X-axis, the Y-axis, and the Z-axis in the Z-axis;
• and
• perpendicularity errors between the X-axis, the Y-axis, and the Z-axis;
• calculating, based on the measured actual error data errors with respect to the arbitrary coordinate position in the machine tool coordinate system, following errors in a three-dimensional space of a set coordinate system having its origin at a reference position Xa, Ya, Za preset in the machine tool coordinate system:
• a positioning error in the X-axis direction in the X-axis feed mechanism;
• a positioning error in the Y-axis direction in the Y-axis feed mechanism;
• a positioning error in the Z-axis direction in the Z-axis feed mechanism;
• translational errors in the X-axis feed mechanism, the Y-axis feed mechanism, and the Z-axis feed mechanism;
• angular errors around the X-axis, the Y-axis, and the Z-axis in the X-axis feed mechanism;
• angular errors around the X-axis, the Y-axis, and the Z-axis in the Y-axis feed mechanism;
• angular errors around the X-axis, the Y-axis, and the Z-axis in the Z-axis feed mechanism;
• and
• perpendicularity errors between the X-axis, the Y-axis, and the Z-axis;
• and
• calculating, based on the calculated errors in the three-dimensional space of the set coordinate system, the relative motion error between the spindle and the table in the three-dimensional space of the set coordinate system.