Calibration of rotary joints in multi-axis machine tools

Abstract

A novel technique is developed and implemented for error quantification in a rotary joint of a multi-axis machine tool by using a calibrated double ball bar (DBB) system as a working standard. This technique greatly simplified the measurement setup requirement and accelerated the calibration of rotary joints. In addition it is highly economical by reducing the complex optics and eliminating the usage of various tooling, instrumentation and accessories. This methodology is capable of measuring the five degree of freedom (DOF) errors out of 6DOF of a rotary joint by using the calibrated DBB system and a point locating fixture. The methodology is implemented on rotary joints of a five axis CNC machine tools. Equation solvers and error modeling technique are implemented and validity of the methodology and authenticity of the results obtained are tested through simulation in UG and Matlab software. The methodology is found extremely feasible pragmatic, quite simple, efficient and easy to use for error characterization of rotary joints of multi axis machine tools.