Dynamic Characteristics Analysis And Parameters Optimization Of Spiral Groove Thrust Bearing

In order to obtain better hydrodynamic effects, the work surface of thrust bearing has some special grooves or steps to form converging wedges, along the direction of the sliding speed. With the converging wedges, thrust bearing can generate better hydrodynamic effects, improve the bearing capacity further. Meanwhile the appropriate converging profile can be advantageous to improve the lubricating performance. Under high-speed operation, compared with other types of thrust bearing, the spiral grooved thrust bearing has higher carrying capacity and smaller friction. In this paper, the model is inclined spiral groove thrust bearing. The transient characteristics and the effects of spiral groove’s parameters on static and dynamic characteristics of the bearing are analyzed. Taking the maximum film stiffness coefficient as optimization goal, geometric parameters of spiral groove are optimized. That establishes a theoretical basis for the design of spiral groove thrust bearing.Firstly, a mathematical model of the hydrodynamic spiral groove thrust bearing is established. Because of the complex structure of spiral grooves, the boundary-fitted coordinate system is used to transform the spiral region into a fan-shaped unit. Then the numerical computation is made on the fan-shaped unit and the Reynolds equation and the film thickness equation are derived.Secondly, the numerical analysis of hydrodynamic spiral groove thrust bearing is made. Lubricating performance is simulated by calculation procedure using finite difference method that worked out in MATLAB. And, the influence of spiral angle, groove number, groove-ridge width ratio and groove depth ratio on static characteristic of inclined spiral groove and common spiral groove thrust bearing is analyzed.Thirdly, perturbation pressure equations are derived and perturbation pressure is solved. Then, the stiffness and damping coefficients of bearing are obtained. The influence of spiral groove’s parameters on dynamic characteristic of inclined spiral groove and common spiral groove thrust bearing is discussed. The spiral groove’s parameters have the almost same influence to dynamic characteristic of the two bearings, but the degree is slightly different; Under the same parameters, dynamic characteristic of the former is best than the latter.Based on nonlinear oil film pressure, inertia force and the external dynamic load, the equation of motion of the thrust disc is established. Under step load and rectangular pulse load, the displacement, velocity and acceleration of thrust disc changing with time are discussed as well as film pressure, minimum film thickness, stiffness and damp coefficients.Lastly, taking the maximum film stiffness coefficient and bearing capacity as goal, designing orthogonal experiment and processing the data variance analyse are to analyse the degree of impact on lubricating performance by spiral groove’s parameters. Taking the maximum film stiffness coefficient as optimization goal, establishing the mathematical model, geometric parameters of spiral groove are optimized by MATLAB optimizing toolbox.