A skin-model-shape based method for predicting rotation accuracy of spindles considering form errors and rotating unbalance

The rotation accuracy of the spindle is crucial to the machining accuracy of the machine tool. This paper proposes a method for analyzing the rotation accuracy of the spindle while taking into account the form error. Unlike previous studies based on the ideal part, the skin model shape method is employed to obtain the assembly deviation of bearings arising from the manufacturing defect including form errors. Then the quasi-static model of ball bearings is established to determine the contact load distribution within the misaligned bearings during non-ideal rotation. On this basis, the prediction model of the spindle is developed to evaluate the rotation error of the spindle, in which the influence of the rotating unbalance is integrated through equivalenting it to a radial load applied to the rotor. Finally, the practical experiment is conducted to verify the correctness of the proposed method, and the influence of different factors on the rotation accuracy is also comprehensively investigated.