Research Of Lubrication Property On Annulus Film Of Large-scale Hydrostatic Bearing

Hydrostatic thrust bearing is the core component of heavy-duty CNC machine tool, which can bear a vertical load and have a lot of advantages, such as small friction, long life, wide speed range, vibrating resistance and so on. Film lubricating characteristics of hydrostatic bearing has a direct impact on working performance, reliability and life of machine tool. Therefore, research on ring gap film of large-scale vertical lathe for hydrostatic bearing table, by using a combination of theoretical analysis, numerical simulation and experiment to study lubricating performance. Details are as follows:Theoretical formula of hydrostatic bearing characteristics on ring cavity are deduced. This research reasonably simplifies the oil pad model based on fluid dynamics and lubricating theory, and deduce theoretical formula of pressure distribution, flow and support stiffness on hydrostatic bearing of ring cavity.Simulation model of gap film is established. This research selects appropriate computer simulation model and boundary conditions based on numerical simulation principle of computational fluid dynamics the finite volume method, and mesh the geometry model by using ANSYS ICEM CFD software. by using ANSYS CFX iterative solution, lubricating flow state and flow field relevant parameters are obtained.This research introduces viscosity-temperature characteristics and analyzes the impact of temperature on viscosity of fluid, further studying the influence of viscosity on the performance of film lubrication. By numerical simulations of oil flow pattern of hydrostatic bearing internal oil cavity and on the film, this research obtains pressure field distribution law, velocity field distribution law and temperature field distribution law of film under the condition of constant viscosity and variable viscosity and analyzes the influence of temperature-viscosity effect on hydrostatic bearing performance.The influence of worktable rotating speed on film lubricating performance has been studied. According to simulation, the area of maximum temperature in different rotating speed can be obtained. The main factors causing temperature changing are analyzed. At the same time, table of the relationship between average temperature rising, average pressure rising and rotating speed will draw.Experimental verification. Film pressure, as well as film thickness measurement experiment is operated on 5m vertical lathe, according to the experimental result, the correctness of the simulation of hydrostatic bearing oil film lubrication performance,static bearing characteristics and theoretical calculation is verified.The research result shows that the influence of viscosity-temperature effect is very significant in research and design of hydrostatic thrust bearing, can not be ignored. Table rotating speed has a great influence on the lubricating properties of gap film, accompanying by the phenomenon of dynamic pressure, so the influence of oil cavity geometric characteristics and rail speed should be considered in the research and design process of hydrostatic thrust bearing.