The influence of journal's roundness on rotating accuracy of aerostatic spindle and precision improvement by time-controlled grinding

Abstract

The roundness of the journal directly affects the radial synchronous error (RSE) of the aerostatic spindle. However, the state-of-the-art ultra-precision grinding machine can only achieve a roundness of 0.2–0.3 µm, which limits the improvement of the rotating accuracy. Hence, novel time-controlled grinding (TCG) is proposed to further converge the rotor's roundness. To provide the machining basis and prediction, CFD is used to quantitatively analyze the effect of roundness on the flow field and a rotating trajectory model is established. Based on the model's guidance, the rotor's average roundness converged to 0.08 µm by TCG, even better than manual lapping, and the RSE decreased from ∼30 nm to ∼11 nm synchronously, proving the model's and TCG's feasibility and potential.