Machining, Measurement, and Control Laboratory
 

 
 
 
 
Identification and compensation of geometric errors in five-axis machine tools with a tilting rotary table using conic trajectories measured by double ball bar
 
Tetsuya Matsushita, Atsushi Matsubara
 
 
 
Abstract

Geometric error, such as a pivot offset of the rotational axis, squareness between axes and so forth, is one of fundamental factors that decrease the machining accuracy for five-axis controlled machine tools. And it is important to identify the geometric errors in order to improve the machining accuracy, so that many methods to identify or diagnose the geometric errors of the rotational axes have been suggested. Meanwhile, the most general method for the accuracy test of five-axis controlled machine tool is the cone frustum machining test, which is prescribed in NAS979. In our previous work, we showed that the geometric errors in five-axis controlled machine tools with a tilting rotary table influence the accuracy of machined cone frustum, and it depends on the location, apex angle, tilt angle or diameter of the cone frustum. It indicates that the geometric errors might be identified with the profiles of cone frustum. In this paper, we suggest a method to identify the geometric errors of linear and rotational axes in five-axis controlled machine tools with a tilting rotary table, which uses the multiple trajectories of the conic motion measured by double ball bar device. Moreover we develop the compensation system of the geometric errors. We also show the result of the compensation of the identified geometric errors by the suggested method.
 
Keywords: machine tool, five-axis control, geometric error, cone frustum, ball bar, identification, compensation.