Research On The Load Carrying Performance Of Hydrostatic Bearings Of Large-scale Ball Mill

Large-scale ball mill, a power machine which has been widely used in mining,metallurgies and chemical industry because of its merits such like large crushing ratio,good stability, strong adaptability. Its large scale trend meets the demand of practiealproduetion and has came to be a trend. As the key component of the ball mill,hydrostatic bearing works under the heavy-load condition, that its load-bearingcapability and stability affects the performance of ball mill directly.Based on the National Natural Science Foundation of China (51265020), thisstudy does a research in two parts of hydrostatic bearings, load-bearing oil film andbushing, which affect the load-bearing capability and the stability, analyzed the affectof design variables on the bearing performance, laid the theoretical foundation for thefuture work. The main research work includes the following:(1) The simplified model of load-bearing oil film is established based on parallelplate flow theories. The relationship of the load-bearing, pressure, flow and filmthickness is deduced. Besides, the CFD simulation model of load-bearing oil film isestablished, and the results has shown a good agreement with simplified model. Thecomparative results as follows: the oil flow result of simulation is approximately1.09times of the result of simplified model at the same film thickness without consideringthe effect of viscosity-temperature and is about1.10times when considering theviscosity-temperature effect.(2) Based on the CFD model, the pressure field distribution, the temperature fielddistribution and the flow is obtained, and the affect of the oil temperature-viscosityeffect, the oil film thickness, the shaft rotational speed and the shaft deflection angleare analyzed. The simulation results show that the hollow shaft deflection angle hasan significant iMPact on the fluid properties of hydrostatic bearing oil film, pressurein oil film gap is asymmetry and deflecting torque is generate on the bearing surface.(3) The simplified contact model of bearing bushing with bearing seat isestablished based on elastic contact theory and the contact pressure distribution of the contact ares is obtained. The results show a good agreement with the contact pressuredistribution calculated by FEA method.(4) The affect of bushing surface curvature on the contact properties and self-aligning properties as contact pressure, self-aligning displacement and self-aligningtorque is analyzed. Besides the contact analytical modal with hollow shaft deflection isestablished, the contact pressure and the contact area is obtained. The realationshipbetween deflection angle, contact pressure and contact area is investigated. Thesimulation results show that axial curvature radius has an effect on axial contactpressure distribution and axial contact width, the maximum contact pressure decreaseswith the increase of the curvature radius while self-aligning displacement increaseatalong with the axial curvature radius; the radial curvature radius has an effect on radialcontact pressure distribution and radial contact width, the maximum contact pressuredecreases with the increase of the curvature radius while self-aligning torque increaseatalong with the radial curvature radius.