A new measuring method for circular motion accuracy of NC machine tools based on dual-frequency laser interferometer

Abstract

A new two-dimensional displacement measurement method to test circular track errors of NC machine tools is proposed, which is based on a dual-frequency laser interferometer. The system resolution can be up to tens of nanometer. This measurement system can inspect the circular track with small radius. And it requires two independent laser interferometers essentially can be simplified to only one laser source now. The measurement system absorbed the optical structure of Michelson interferometer. Reflecting arm end is plane reflecting mirrors and other arm end is corner reflector. The light way realizes 4 times subdivision, which can improve the measuring resolution. The optical setting consists of laser measuring head, 50% beam splitter, two measurement modules, two plane reflecting mirrors, etc. A beam of laser light from the measuring head, is equally split into two beams to measure displacements of X-direction and Y-direction. Under conditions of various feed speeds and radiuses, experiment results show that suggested method is feasible and effective for circular tests of NC machine tools. Its uncertainty of measurement is micron. Moreover, the system structure is simple and easy operation.