Simulation And Experimental Study Of Spindle System Dynamic Characteristics Of Ultra-high Speed Grinder

Ultra-high speed grinding technology is the latest high efficient grinding technology of the21st century. It can not only greatly improve the efficiency, but also significantly improve the quality of grinding. Grinding spindle is the most critical component whose dynamic and static performance has significant impacts on that of the machine. Therefore, domestic and abroad researchers pay much attention on it as well as the relationship between load capacity and eccentricity. Various methods of spindle dynamic characteristics simulation are raised. However, it is shown that systematic research is lacking. Key issues that will affect the accuracy of the spindle have not been effectively solved, such as simulation of dynamic characteristics of bearings, spindle system surface modeling and the impact of grinding force on the spindle system.At the beginning, current situation at home and abroad about the research in dynamic characteristics of hybrid bearing system is reviewed. Based on this, a steady mathematic model of spindle system is built according to dynamics, static and dynamic bearing spindle system theory. Theory, simulation and experiment research are performed on its static and dynamic properties to obtain the dynamic characteristics and influence factors. Verify the feasibility and accuracy of using finite element method to simplify Hybrid Bearing, establish spindle system mathematical model and solve the dynamic performance of the spindle system.In the following the main research work are listed:(1) Studied existing structural features of the hybrid spindle system, Static Stiffness of the spindle system is analyzed, combined with grinding characteristics, understand the situation of static stiffness.(2) Current methods of hybrid bearing analysis are reviewed. The movement mechanism is analyzed and oil film pressure is solved by using Reynolds equation for the derivation of dynamic parameters. CFD Thought is used to establish oil film finite element model by fluent software, then use it to solve oil film pressure, through simulation of digital methods to understand Dynamic performance about oil film. (3) A dynamic model for the spindle system is established to simplify its structure and load. The hybrid bearing is simplified as a spring damper system, using the Finite Element Method to solve its mode, extract its vibration and analysis its harmonic response. The dynamic characteristics are analyzed and the optimal design value is obtained according to its stability under load excitation and its parameters optimization.(4) Modal analysis of the ultra-high speed grinding is performed using the method of modal parameters picking up to obtain the admittance acceleration curve, extract modal parameters and damping ratio, differential equations of motion of spindle system is established, then get the dynamic performance of the spindle.The accuracy and feasibility of the Finite Element Analysis of the spindle system are verified by comparing the experiment result with that of Finite Element Analysis, as well as the reliability of the parameterization of hybrid bearing dynamic performance. The causes leading to errors are found and dynamic parameters are corrected. This research provides a theoretical basis and reference for spindle system dynamic analysis of other structure or machine.