Ballbar testing tune-up method for machine tool

A method for calibrating a Computer Numerical Control Machine (CNC Machine), the method comprising:

• providing a CNC Machine, the CNC Machine including:
• a tool head;
• at least two servomotors corresponding to at least two orthogonal directions of movement of the tool head, and a first direction of movement is defined as a first axis and a second direction of movement is defined as a second axis;
• a servocontroller for controlling a corresponding one of each of the at least two servomotors, each servocontroller including at least a position controller and a velocity controller coupled thereto;
• a processor;
• and
• an optical ruler coupled to the processor;
• executing a plurality of ballbar tests using the optical ruler as a measurement tool for determining which of the two orthogonal directions of movement has a response characteristic less than that of the other, wherein execution of each ballbar test includes:
• actuating each servocontroller to control a corresponding one of each of the at least two servomotors to selectively move the tool head in at least a portion of a circular path with respect to the at least two orthogonal axes;
• and
• obtaining a phase characteristic and a peak-value characteristic with respect to a tracking result with respect to the at least a portion of a circular path, wherein the phase characteristic is an average value of a difference between a radius sampled at a position of the first axis and the second axis with a contour error fixed cycle in a corresponding ballbar test and an average radius of the corresponding ballbar test, wherein the peak-value characteristic is a difference of peak values at the first axis and the second axis in the corresponding ballbar test;
• generating a Lagrange interpolation polynomial subsequent to execution of each ballbar test, and increasing an interpolation order of a corresponding Lagrange interpolation polynomial according to a number of executed ballbar tests, and inputting at least into a corresponding Lagrange interpolation polynomial a servo controller parameter of a servocontoller of a respective servomotor associated with a corresponding ballbar test and at least one of the phase characteristic and the peak-value characteristic associated with the corresponding ballbar test for generation of a proposed servo parameter;
• and
• inputting the proposed servo parameter into the processor for selectively actuating the at least one of a position controller or a velocity controller of a respective servocontroller of a corresponding servomotor to appropriately compensate the corresponding response characteristic in the respective direction of movement, thereby improving a contour precision of the tool head of the CNC Machine.