Research On Hybrid Bearing Spindle System Of High Efficiency & Precision CNC Grinding Machine

The dynamic and static pressure spindle system of the precision CNC grinding machine adopts the dynamic and static pressure bearing as the bearing unit,which has many advantages and been well applied.As the core components,dynamic and static pressure bearing have important research value.According to the specific requirements of the precision CNC grinding wheel spindle system and the dynamic and static pressure bearings it uses:(1)This article introduces the basic control equations used in designing the dynamic and static pressures bearing and based on the theory of fluid lubrication,a mathematical model for the distribution of steady-state temperature field and oil film pressure field of dynamic and static pressures bearing is established.The influence of the shape error(roundness error and cylinder error)on the bearing performance of dynamic and static pressures bearing in the shallow and deep cavity was analyzed by using the 3D fluid simulation software FLUENT.(2)By using the FLUENT software and ANSYS Workbench simulation software,the article analyzed the change of bearing oil film performance in the case of spindle axis deflection and researched the mutual influence between the deflection caused by the load caused by the main shaft and the axis misalignment caused by manufacturing and assembly errors.And the thermal deformation,elastic deformation and composite deformation of the bearing-spindle part were analyzed by solid-liquid coupling.(3)Based on SolidWorks and ANSYS Workbench,the three-dimensional model and finite element model of dynamic and static pressures bearing for grinding wheel spindle system was established,and modal and harmonic response analysis was carried out.This paper used the finite element numerical simulation to calculate the spindle eight order natural frequency of the system and the corresponding vibration mode.The influences of wheel end suspension elongation,bearing support spacing and the position of the thrust bearing on the critical speed and dynamic sti ffness of the spindle system were analyzed.Furthermore,simulation of the thermal deformation of the main shaft was simulated.On the basis of it,the measures to improve the dynamic and thermal characteristics of the main shaft system were proposed.(4)Based on the 30 HD high-speed dynamic and static pressures main shaft experiment platform of Hunan University,the thermal characteristics of the high-speed motorized spindle system under different working parameters were tested.Comparing the experimental data with the simulation results,the results show that there is a certain error between the simulated value and the measured value on the whole,but within the acceptable range,the effectiveness of the simulation method is proved.In addition,the HKY121-01 dynamic and static pressures spindle system was also used to measure the rotation accuracy.