Abstract: The radial passive permanent magnet bearing is not stable in the axial direction, resulting in difficulty in assembly. In addition, due to material and magnetization reasons, the actual magnetic field of permanent magnets is generally lower than the theoretical value, resulting in errors in the stiffness calculation of such bearings. In order to solve the above problems, the axially magnetized repulsive radial bearing is taken as the research object. Firstly, a mathematical model of the bearing is established using the equivalent magnetic charge theory, and the axial magnetic force and axial stiffness during the assembly process, as well as the radial magnetic force and radial stiffness, are calculated. Then, a ball joint is introduced to establish a single span rotor static model, and the load distribution and corresponding radial stiffness (horizontal stiffness and vertical stiffness) of the two bearings after assembly are solved. Finally, an experimental platform is built to measure axial magnetic force, axial stiffness, and radial stiffness, and complete suspension of the rotor is achieved. The theoretical calculation and finite element simulation results are consistent, indicating that a 1.5 kg permanent magnet can theoretically generate a maximum axial magnetic force of 1 368 N and a radial magnetic force of 700 N. The experimental results show that due to insufficient magnetization, the maximum axial force decreases to 1 028 N; The experimental bearing can completely suspend an 18 kg rotor, and the measured axial and radial stiffness orders of magnitude are 10⁵N/m and 10⁴N/m, respectively. The research work provides a theoretical basis for the subsequent research on the load-bearing and dynamic characteristics of permanent magnet sliding bearings.

Key words: permanent magnet bearings, load-bearing characteristics, stiffness, equivalent magnetic charge theory