Error Calibration on Five-axis Machine Tools by on-the-machine Measurement of Artifacts using a Touch-trigger Probe

As a basis to improve the motion accuracy of five-axis machining centers, it is important to develop a methodology to measure it in an accurate, efficient, and automated manner. This paper proposes a scheme to calibrate error motions of rotary axes by on-the-machine measurement of artifacts by using a contact-type touch-trigger probe installed on the machine's spindle. Location errors, defined in ISO 230-7, of rotary axes are the most fundamental error factors in the five-axis kinematics. A larger class of error motions can be modeled as geometric errors that vary depending on the angular position of a rotary axis. The objective of the present scheme is to identify not only geometric errors, but also such position-dependent geometric errors, or “error map,” of rotary axes. Its experimental demonstration is presented.