Study On The Dynamic Performances Of Oil Film Bearing With Consideration Of Machining Errors

The research subject of the dissertation stems from the “Research on working principle of the new type throttling governor for high performance journal bearing” supported by National Natural Science Foundation of China under the project no. 51075409.The rotary machinery trends to high speed, heavy loading and high precision, and the oil film bearing as a typical support element have to satisfy the requirements of high performance. To improve its dynamics performance, the fitting clearance between the journal and spindle should be with a tight gap closed to the machining errors. This means that the manufacturing error will have significant impact on its performance; it requires keeping in a high standard of manufacturing accuracy. However, this solution will not only increase the cost, but also low the yield rate. This research is dedicated to build the foundation lubrication theoretical model with consideration of manufacturing errors, and propose a new hybrid throttling governor that is combined by traditional throttling and servo controlled throttling to eliminate the effects of manufacturing errors. Based on the propose model, the dynamics performance of proposed hybrid throttling oil film bearing system are compared to the traditional system, and how the manufacturing errors impact to its performance are investigated as well as the position and rotatory precisions. This research will also lead to the new theoretical foundation for the oil film bearing and a low cost solution to high performance system.The main contributions of this dissertation are:① A new model for oil film bearing with consideration of machining error is proposed based on the traditional lubrication theory, and the oil film clearance function, Reynolds equation and flow continuity equation have been reconstructed in the model.② A new hybrid throttling governor is proposed with combination of traditional throttling and servo controlled throttling for the oil film bearing system. The PID control system is adapted and the genetic algorithm is used to optimize the controller. The dynamics equation of spindle is rewritten based on the proposed model.③ The effect of the work conditions, e.g. loading, speed, oil viscosity, etc., are investigated by compared studies between traditional throttling and hybrid throttling oil film bearing system. The influence of working condition on the loading capacity, the stiffness, minimum oil film thickness and flow rate are investigated.④ The impact of size errors and form errors on the load capacity, oil film rigidity, oil film thickness and flow rate, and the pressure distribution have been comparatively analyzed as well as the position accuracy and rotate accuracy of spindle.⑤ The experimental setup is designed for verifying the proposed model and numerical simulation. The machining errors of the journal are measured and the dynamics errors are isolated for comparisons.The proposed model with considerasion of the machining errors will lead to solid foundation of insight of the oil film bearing. The hybrid throttling governor for oil film bearing system has eliminated the effect of machining error, and therefore, it has high potential for application in load speed, heavy load, and high precision rotatory machine. Also, the theoretical and numerical studies will be significantly impacted on design and analyses for oil film journal bearing.