US 12,216,446 B2
Ballbar testing tune-up method for machine tool
Ching-Hung Lee, Hsinchu (TW); and Shun-Fu Wu, Hsinchu (TW)
Assigned to National Yang Ming Chiao Tung University, Hsinchu (TW)
Filed by NATIONAL YANG MING CHIAO TUNG UNIVERSITY, Hsinchu (TW)
Filed on Oct. 22, 2021, as Appl. No. 17/451,924.
Claims priority of application No. 110129167 (TW), filed on Aug. 6, 2021.
Prior Publication US 2023/0043926 A1, Feb. 9, 2023
Int. Cl. G05B 19/401 (2006.01); B23Q 17/22 (2006.01); B23Q 17/24 (2006.01); G05B 19/404 (2006.01)
CPC G05B 19/401 (2013.01) [B23Q 17/22 (2013.01); G05B 19/404 (2013.01)] 6 Claims
OG exemplary drawing
 
1. 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.