The Experimental Research On Permanent Magnetic Bearing

Magnetic bearing have many advantages such as no frication, no wear, no lubricant equipment and long service life, they are now moving beyond promise into actual service in such applications as aircraft, electric power generation, high speed and high precision machine tool, petroleum refining and robots. Magnetic bearing with permanent magnet to provide levitation force have lower power consumption, smaller volume, more compact structure. It becomes the important aspect of magnetic bearing.Based on dot magnetic charge theory, radial magnetized model and axial magnetized model are established. The models embody the relationship between radial displacement and loads. Comparing the radial magnetized model and axial magnetized model, for the performance of the loads and stiffness, the result of the radial magnetized model is better. Machining the axial magnetized bearing is easier than machining the radial magnetized bearing. Axial magnetized bearing are chosen.The permeability of iron is big, magnetic reluctance of stainless steel is big, so, the two kinds of material are chosen as the material of the magnetic bearing. Use ANSYS to analyze the effect of iron and stainless steel for the density and direction of magnetic flux, iron can assemble flux, stainless steel affects the density and direction of magnetic flux little. That means the choices are suitable. Finish designing and machining the bearing assembly.For testing the performance of the bearing, finishing designing and machining testing station, the performance of testing station is stable, operate easily. The performance of testing station meets the requirement : maximum loads is 17N, maximum speed is 4000r/min.The trend of relationship between radial displacement and loads is the same as the theoretic. Speed affects the value of the radial sum displacement, at certain speed (lower than 1000r/min), the higher the speed is, the bigger the value of the radial sum displacement is.Through the trial, actual loads is smaller than theoretical loads, the problem may be magnetic flux leakage machining, accuracy of bearing and non - uniform magnetization of magnetic rings. Improve them further,Through studying on the trial results of stiffness of bearing, speed affects the radial displacement much. Once the speed is bigger than the certain value, the direction of radial displacement is up. Maybe the air-dynamic lubrication makes that. The reason and the regulation need be studied further.