| Ultra-high speed grinding can remarkably improve the surface quality and machining precision of machined parts,and can realize the perfect combination of high quality and high efficiency machining.Liquid lubricated hybird bearing has many advantages such as high rotary precision,good dynamic rigidity and damping vibration-reducing performance,long service life and so on,and has a wide application prospect in the field of ultra-high speed grinding electric spindle.The design and analysis of hybird bearing are based on the traditional Reynolds equation,the influence of oil film curvature,inertia term and radial flow field on bearing performance is neglected,and the transient change process of axial position under disturbed load is not paid enough attention.In this paper,the hybrid bearings with liquid lubrication for grinding motorized spindle with ultra-high speed and high load are studied,and the main work of hybrid bearing with typical deep and shallow cavity structure is as follows:(1)Based on the CFD method of Navier-stokes equation,considering the influence of oil film curvature,inertia term and radial flow field on bearing performance,the hybird bearing is numerically solved.In this paper,the hybrid pressure bearing in the typical structure form is studied,considering the thickness of oil film,using ICEM CFD software,and the structure grid division of O-block partition is divided into three-dimensional model grids,The fast modeling of different eccentricity oil film is realized by using dynamic mesh updating method.(2)CFD software FLUENT using finite volume method,in this paper,the pressure field and temperature distribution of hybrid bearing are analyzed by numerical calculation,and the influence of rotational speed and eccentricity on the oil film pressure field and temperature field distribution is studied.Considering the oil film rupture phenomenon of oil film bearing,The influence of negative pressure on the film bearing capacity of oil film pressure distribution is analyzed.(3)Based on the 6DOF model and the dynamic grid calculation method,the hybird bearings with typical structural forms are calculated and analyzed,and the transient process of the axial trajectory under external loads is calculated by using nonlinear iterative method,and the computational Analysis program is developed.By embedding the UDF macro program in order to realize the perturbation of the position of the axle neck by moving the grid updating method,by solving the navier-stokes equation,the transient oil film Force after the position change of the journal is obtained,and then the stiffness and damping dynamic coefficients of the oil film of the hybrid bearing are solved by the difference method of the numerical calculation.The variation rule of dynamic characteristic coefficients of hybrid bearing under different rotational speed is compared and analyzed. |
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