Machining, Measurement, and Control Laboratory

Thermal Test for Error Maps of Rotary Axes by R-Test
Soichi Ibaraki, Cefu Hong

Thermal distortions are regarded as one of major error factors in a machine tool. ISO 230-3 describes tests to evaluate the influence of thermal distortions caused by linear motion and spindle rotation on the tool center position (TCP). No test is described in these standards on the thermal influence of a rotary axis. Furthermore, conventional thermal tests only measure thermal influence on the positioning error at a single point, not error motions of an axis. This paper proposes a method to calibrate thermal influence on error motions of rotary axes in five-axis kinematics by the static R-test. The R-test measurement clarifies how error motions of a rotary table changes with the rotation of a swiveling axis, and how error motions are influenced by thermal changes. Experimental demonstration will be presented.
Keywords: R-test, five-axis machine tools, thermal test, error map, error motion.