Ceramic bearings have a good dynamic output performance under an ultra-high, ultra-low temperature due to their small deformation property. Based on the Harris and Palmgren empirical equation, this article establishes the thermal transfer model of a ceramic motorized spindle. The thermal deformation of a ceramic angular contact ball bearing is calculated. A dynamic and thermal coupling model of the ceramic motorized spindle is built using the Hertz contact theory, which can determine the optimal preload force under different rotating speed conditions. The influence of different temperatures, preload, and rotation speeds on the bearing vibration characteristics was studied. The accuracy of the dynamic and thermal coupling model was verified by the motorized spindle experimental platform. The results show that the thermal deformation of the bearing is an important influencing factor for the output of the dynamic characteristics. Considering the thermal displacement of the bearing, the simulation accuracy of the ceramic motorized spindle-bearing system is in good agreement with the experimental results. By adjusting the bearing preload, the parameters of the rotating speed can effectively reduce the temperature rise and suppress the vibration. The spindle-bearing system model provides a theoretical basis for the dynamic development of a high-speed ceramic bearing.

The thickness of the oil film in ceramic ball bearings varies greatly at starved lubrication conditions, thus leading to non-uniform contact between the balls and raceways in the circumference. The lubrication parameters have a direct impact on the thickness of the oil film and then affect the dynamic characteristics of the ceramic ball bearings. A nonlinear dynamic model of ceramic ball bearing with limited lubrication is presented in this paper, and parametric studies on the effect of lubrication parameters are conducted. In starved conditions, the uneven contact between the ball and ring leads to changes in vibration, and the inner ring vibration is applied to evaluate the degree of starved lubrication. The results show that as the oil quantity increases, the bearing stiffness increases and results in increased peak frequency. As the oil quantity decreases, the thickness of the oil film reduces, resulting in the bearing vibration increase. The research findings provide a theoretical reference for ceramic ball bearing design and have guided significance for improving the service performance of ceramic ball bearings.

Rolling bearing fault diagnosis is significant to the stable operation of rotating machinery systems. However, the fault data collected in practical engineering is seriously imbalanced, which degrades the diagnosis performance. A DRNet intelligent fault diagnosis model was proposed in this paper based on the probabilistic diffusion model to enhance fault diagnosis performance under imbalanced data. This paper utilized a probabilistic diffusion model to learn a deep semantic representation of fault data, which in turn generates high-quality fault features to balance the number of fault samples. Moreover, we utilized the deep features of fault signals to build a feature metric module that optimized the features of the generated samples. This enhances the accuracy and diversity of the generated data. Finally, the fault categories of the samples were identified using the residual network after data enhancement. The experimental results indicate that compared to other common methods, our method can more effectively fit the feature distribution of real samples resulting in generated samples with higher similarity and exhibiting good stability and accuracy when processing bearing unbalanced fault data.

Full ceramic bearing can work under a wide range of temperatures, but the thermal deformation difference between the ceramic outer ring and steel pedestal has a great increase with the rise of temperature and leads to obvious impact and friction. In this paper, the thermal deformation difference is considered and the fit clearance is taken as the boundary condition of the dynamic model. Investigations on the dynamic response of the outer ring are conducted, and the effect of thermal‐related fit clearance is analyzed at different working temperatures and rotation speeds through parametric study and experiments. Results show that the vibration of the outer ring grows with the temperature and shows different changes with rotation speed as the temperature changes. The variation of working temperature brings difference in the interactions between the outer ring and the pedestal, and the trends of vibration with rotation speed also change at different temperatures. Impact and friction make great contributions to the interactions between the outer ring and the pedestal and show different changes with temperature. This study puts forward a method for the calculation of bearing vibration at variable temperatures and provides theoretical basis for the application of the full ceramic bearings.

Full‐ceramic ball bearings are widely applied in wide temperature ranges due to their excellent thermal shock resistance, and the condition monitoring and fault diagnosis are mainly conducted through the spectrum analysis based on the defect frequencies. However, the outer ring has a spinning motion in the temperature‐related fit clearance, which leads to the deviation of raceway defect frequencies, and is not conducive to the fault diagnosis. In this paper, the temperature‐related fit clearance is considered in the dynamic model, and defects are added on the inner raceway and outer raceway. The motions of the rings are calculated and analyzed in the frequency domain, and the trends of peak frequencies with temperature are investigated. Simulation and experimental results show that the spinning speed of the outer ring increases with temperature, and the defect frequencies exhibit obvious deviation in wide temperature ranges. In a temperature range of 500 K, the defect frequencies exhibit deviations of over 3%, which is obvious in the defect frequency identification. The results provide insights on the full‐ceramic ball bearing dynamics and help with the fault diagnosis and status monitoring of the relevant devices.