Research On Magnetic Bearing Of Unequal Pole Area

There is a lot of wear between the spindle and bearing during high-speed cutting process. Magnetic bearing is used to replace rolling bearing during the machining process. The current in the coils of different poles are not equal because of static load. It will reduce the service life of the magnetic bearing. A new method of designing the unequal pole areas are proposed to solve the problem. First of all, the working principle of the structure is introduced. The parameters of the structure of radial and axial AMB of unequal pole areas are designed. Secondly, the formula of maximum carrying capacity of the new structure is derived and the relationship between static load and controlling current in the AMB of unequal pole areas is researched by theoretical calculation and finite element simulation. The results show that static load can be counteracted without controlling current in the AMB of unequal pole areas and within the maximum carrying capacity range, the controlling current in the new structure is smaller than that in the traditional AMB. When the pole areas ratio is smaller, it can offer bigger force to counteract static load. Thirdly, the analysis of the linear-degree of magnetic force and coupling in different conditions is finished by finite element simulation. The analysis of coupling in the AMB of unequal pole areas is finished by finite element simulation. Experiments are done to test the performance of the new structure including rising-up, static suspension, suspension under interference, high-speed rotating suspension, measurement of maximum carrying capacity and the research of relationship between static load and controlling current. The experimental results show that the rotor can rise up in 320 ms. The peak-peak values of rotor vibration are about 900 mV. The performance of the new structure is good. The upward and downward maximum carrying capacities are 438 N and 220 N respectively.