Rolling bearings are essential components in various automated devices, playing a pivotal role in ensuring the smooth operation of mechanical systems. In applications that involve extreme conditions, such as spacecraft, high-speed machine tools, and drones, traditional steel bearings may not be suitable due to limitations related to temperature, speed, and lubrication. In such scenarios, full ceramic ball bearings (FCBB) have gained prominence due to their high stiffness and exceptional thermal shock resistance. However, FCBB systems often feature ceramic outer rings mounted in steel pedestals, leading to a significant difference in thermal expansion coefficients between the two materials. This discrepancy results in varying fit clearances over a wide temperature range, affecting the interaction between the outer ring and the pedestal, and consequently, the sound radiation from the bearing system. Recent research has highlighted the potential of sound radiation characteristics as indicators of the operational performance of FCBB systems, particularly when dealing with ceramic materials known for their sound radiation efficiency. The new study published in the Journal of Sound and Vibration led by Professor Xiaotian Bai and Professor Huaitao Shi from Shenyang Jianzhu University, focused on developing a comprehensive sound radiation model for FCBB systems that accounts for temperature-related fit clearances. By establishing new geometric and force boundary conditions and conducting experimental investigations, the study aims to shed light on the impact of temperature, rotational speed, and radial load on sound radiation characteristics, thereby providing valuable insights into the operational status of FCBB systems.
The research approach adopted by the authors integrates model-based calculations with signal acquisition and conditional recognition to monitor the conditions of FCBB systems. They examined the effects of various working condition parameters, such as temperature, rotational speed, and radial load, on sound radiation. Sound pressure levels serve as indicators for assessing changes in mating gap under different loads and temperatures. The accuracy of the model is established through a comparison of monitoring results with theoretical predictions.
The primary factor influencing the acoustic radiation of all-ceramic ball bearing systems is identified as mating clearance. The researchers utilized sound pressure levels as indicators to evaluate the intensity of sound radiation. The influence of working conditions on sound radiation can be effectively analyzed by comparing changes in various influencing factors. They successfully present a sound radiation model for FCBB systems, taking into account temperature-related fit clearance. This model is used to investigate the impact of all-ceramic ball bearings and steel housings on acoustic radiation as mating clearance changes. Notable observations from the study include the significant effect of mating gap on acoustic radiation and the variation of sound radiation indicators, such as peak angle and directivity, with changing working conditions. The study’s approach is validated through theoretical analysis, with monitoring results closely aligning with theoretical predictions.
The study’s findings underscore the significance of understanding how fit clearance variations in wide temperature ranges impact the interactions between FCBB components, leading to changes in sound radiation characteristics. Notably, the main frequency components in sound radiation are attributed to the rotating frequency and its first four-order harmonic frequencies, with the rotating frequency being the dominant contributor. The fit clearance-induced separation of the outer ring from the pedestal introduces a new source of interaction, encompassing both friction and impact sound. The friction-impact ratio varies with temperature, and the interactions between bearing components are influenced by excitation frequencies and loads. Consequently, sound pressure levels increase monotonously with temperature but exhibit inflection points concerning rotation speed and radial loads. The location of peak angle, a key parameter in sound radiation, is influenced by resultant forces and friction-impact interactions. The authors highlighted that the polarization of sound radiation, as indicated by parameters like Gs and Ψ, is significantly influenced by fit clearance and varies with temperature. This polarization performance reflects uneven interaction conditions between FCBB components, indicating that increased fit clearance not only amplifies sound radiation but also intensifies and imbalances component interactions. The researchers acknowledged that choosing a tighter initial fit clearance can mitigate these effects.
In conclusion, Professor Xiaotian Bai and Professor Huaitao Shi from Shenyang Jianzhu University have presented a sound radiation model for FCBB systems, accounting for temperature-related fit clearance variations. Their research has illuminated the impact of working condition parameters, such as temperature, rotation speed, and radial load, on sound radiation characteristics. Key findings emphasize the crucial role of fit clearance in affecting sound radiation, with rotating frequency dominating the sound spectrum.
Xiaotian Bai, Huaitao Shi, Ke Zhang, Xiaochen Zhang, Yuhou Wu, Effect of the fit clearance between ceramic outer ring and steel pedestal on the sound radiation of full ceramic ball bearing system, Journal of Sound and Vibration, Volume 529, 2022, 116967,