THE LASER BALL BAR - A NEW INSTRUMENT FOR MACHINE-TOOL METROLOGY

Current techniques for mapping the volumetric positioning errors of ma chine tools are time and labor intensive. To address these shortcoming s, a linear displacement measuring device is introduced to rapidly and easily determine tool positions via trilateration. The laser ball bar (LBB) consists of a laser interferometer aligned within a telescoping ball bar. The design of the device is discussed and an error budget i s developed to estimate its predicted accuracy. Results of repeatabili ty and linear accuracy tests of the assembled prototype LBB are given. The LBB is used to map the volumetric errors of a two-axis turning ce nter. Comparison of the LBB error map and the error map obtained throu gh parametric error measurements shows the LBB can accurately map the machine errors in a timely manner.