Study On Loading Characteristic Of Parallel Micro-Channel Compensated Aerostatic Thrust Bearing

As aerostatic bearings have the advantages of high movement precision, long life and no pollution, therefore, they can be used widely. The stiffness and stability should have higher requirements with the development of super precision technique but they are contradicted and difficult to considerate both. At this point, under the condition of ensuing aerostatic hearings stable, the gas film stiffness maximization is significant and difficult in the research of aerostatic bearings.Based on aerostatic bearings technology at home and abroad, this paper takes self-designed parallel multi-micro channel aerostatic thrust bearings for the study to improve static characteristics and stability of aerostatic bearings. The parallel multi-micro channel aerostatic thrust bearings were studied through theoretical, simulation and experimental analysis to optimize the gas hydrostatic bearing design, which lay the foundation on the practical applications of large work platform and ultra-precision machine.Established a static and dynamic mathematical model of parallel multi-micro channel aerostatic thrust bearings.Based on the mathematical model, it derived static parameters of aerostatic thrust bearings, established air resistance model for throttle system, and analyzed resistance of multi-micro channel through air resistance potential flow network analysis, thus determining the impact factor of throttle system and gas film air resistances on static characteristics of aerostatic bearings. In dynamic mathematical model, It derived dynamic stiffness and damping expression of aerostatic thrust bearings through small parameter perturbation theory, illustrated calculation method of gas film dynamic stiffness and dynamic damping for aerostatic thrust bearings, reasonably liberalized gas film pressure systems and simplified equations, meanwhile, analyzed variation and influencing factors of dynamic stiffness for multi-micro channel. In the dynamic mathematical model based on the use of small parameter perturbation theory derived parallel multi-micro channel aerostatic thrust bearing dynamic stiffness and dynamic damping expression giving aerostatic thrust bearing gas film stiffness, dynamic damping calculation method, gas film pressure systems and a reasonable linearization and simplified equations, analyze parallel multi-micro channel aerostatic thrust bearing dynamic stiffness variation and influencing factors.On the basis of theoretical analysis, the static and dynamic characteristic of parallel multi-micro channel aerostatic bearing were simulated through FLUENT software.Static characteristic simulation calculation can visually see flow characteristics and pressure distribution in gas film field of air in the throttle access of parallel multi-micro channel aerostatic bearing and the pressure acting on the bearing trends, draw static characteristic curve, point out low characteristics at gas film entrance area and pressure recovery zone. It also mentioned air velocity characteristics, specific factors of pressure rise after steep drop pressure in small and large gaps, and the reasons for whether there generates shock wave in the process of pressure recovery. Numerical calculation results show that static pressure axial has high load capacity for pressure, load and gas flow rate increases in high-pressure zone. The analysis on stiffness improvement factor of parallel multi-micro channel aerostatic bearing laid a theoretical foundation on the development of high-pressure air bearing. Simulation of the dynamic characteristics calculated fixed gas pressure and impact factors of cutting system on dynamic bearing stiffness and analyzed the influence of gas pressure and disturbance frequency on dynamic properties of aerostatic thrust bearing and its stability.Parallel multi-micro channel aerostatic bearing experiment station was designed, which can meet S-type force sensors, inductive micrometer probe, miniature pressure sensors and linear displacement sensors simultaneously. The loading mechanism of the experiment station used spring-loaded principle to achieve a load of continuity and stability, designed a static performance measurement programs for parallel multi-micro channel aerostatic bearing and software to measure gas film thickness and stiffness according to the requirements of measuring system.The software Implemented the synchronous acquisition of serial transmission inductive sensors measurements and load values measured by data acquisition card as well as point values and calculated value of the gas film stiffness, making the measurement data be stored, real-time image visualized, and a visual display of the data and be printed out.Finally, the values measured through the experiment and the comparative analysis of static experiments, theoretical research, and numerical calculation proves that the physical model and the findings on the basis of it in the design are reliable. The achievements in this research can enrich and develop gas lubrication theory and broaden the ideas in practical applications of aerostatic bearing design, which provides a more complete rational and effective way.