Multi-objective Optimal Design Of Ultra-high Speed Grinding Electro-spindle Hydrodynamic And Hydrostatic Bearing Structure

As the core component of ultra-high speed grinding motorized spindle system,the performance of hydrostatic bearing directly affects the machining accuracy and reliability of motorized spindle.It is urgent to ensure the stability and reliability of the bearing performance for the dynamic and static pressure bearing which is often in the ultra-high speed operation state,so it is necessary to analyze the bearing characteristics.In the traditional design scheme of static and dynamic bearing,the feasible scheme which meets the design requirements is generally obtained,which can not guarantee the optimal performance of the bearing.In order to improve the working performance of the bearing,it is necessary to optimize the design of the dynamic and hydrostatic bearing to obtain the optimal design scheme.In this paper,the deep shallow cavity hydrodynamic and hydrostatic bearing with typical cavity structure is studied(1)In order to study the performance of hydrodynamic and hydrostatic bearings with deep and shallow cavities,the CFD software FLUENT based on Navier Stokes equation was used to model and simulate the hydrodynamic and hydrostatic bearings.Considering the oil film size of hydrodynamic and hydrostatic bearings,the modeling work is carried out in micron level.In order to ensure the speed and quality of subsequent calculation,the o-block method is adopted in ICEM CFD software to divide the dynamic and static pressure bearing into structured grids.The dynamic grid is processed by CFX software to realize the change of oil film eccentricity and simplify the modeling work.(2)Based on the oil film divided into structured grids,the simulation calculation of deep and shallow chamber hydrodynamic and hydrostatic bearing is carried out.The influence mechanism of structural parameters and working parameters such as oil supply pressure,spindle speed,oil inlet diameter,initial oil film thickness,shallow cavity depth on the bearing capacity,oil film stiffness and temperature rise is studied under different eccentricity conditions,which lays the foundation for the subsequent optimization design The results show that the optimal design of hydrodynamic and hydrostatic bearings is a multi factor and multiobjective problem,rather than a single factor and single objective problem.(3)Based on the analysis of bearing characteristics of hydrodynamic and hydrostatic bearings,taking the maximum bearing capacity,the maximum oil film stiffness and the minimum temperature rise as the objective functions,taking the oil inlet aperture,initial oil film thickness and shallow cavity depth as design variables,and taking the range of parameters as the constraint conditions,the genetic algorithm is used to carry out multi-objective optimization design of hydrostatic bearings to find the optimal solution set The results show that the bearing capacity,oil film stiffness and temperature rise of the optimized bearing are better than those before optimization,which verifies the feasibility of the optimization design.