Machining, Measurement, and Control Laboratory

Construction of an error map of rotary axes on a five-axis machining center by static R-test
Soichi Ibaraki, Chiaki Oyama, Hisashi Otsubo

This paper proposes an efficient and automated scheme to calibrate error motions of rotary axes on a five-axis machining center by using the R-test. During a five-axis measurement cycle, the R-test probing system measures the three-dimensional displacement of a sphere attached to the spindle in relative to the machine table. 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 this paper is to present an algorithm to identify not only location errors, but also such position-dependent geometric errors, or "error map," of rotary axes. Its experimental demonstration is presented.
Keywords: R-test; Five-axis machine tool; Calibration; Error motion; Location error; Error map