Prediction of the degeneration of radial error motion of a motorized spindle considering the load

The radial error motion of the motorized spindle directly affects the machining accuracy, machining efficiency and machining stability of the CNC machine tool. In order to accurately grasp the degradation law of the radial error motion of the motorized spindle, this paper carried out the theoretical and experimental research on the degradation of the radial error motion of the motorized spindle considering the load condition from the perspective of bearing wear. Through the Hertz contact theory and Archard wear theory, the contact analysis and wear analysis of angular contact ball bearings were carried out. Based on the relationship between the bearing clearance and the radial runout of the shaft end of the motorized spindle, a degradation model of the motorized spindle radial error motion is established. Load condition factors such as load, speed, and time are introduced into the model, and the degradation model under a single condition is improved to a radial error motion value degradation model considering the load condition. A test plan for the degradation of the motorized spindle radial error motion was developed, the loading test was carried out using the load spectrum which can simulate the real working conditions, and it was obtained that the radial error motion value degradation of the 150-type motorized spindle in 300 h was 1.87 μm. According to the degradation model of motorized spindle radial error motion considering load conditions, the degradation is calculated to be 1.7 μm, which only has a small deviation from the degradation test results that verifies the accuracy of the model. The model can be used to comprehensively grasp the radial error motion degradation law of the motorized spindle and predict its operating state.