| Hydrostatic bearing is one of the core components of DVT1000 vertical CNC lathe. In practical machining process, along with the rotation of the working table, the surface of hydrostatic oil film is affected by differential pressure flow, shear flow and inertial flow. The surface temperature of oil film is increased, the oil film viscosity is changed, and the oil film thickness is decreased gradually. Eventually, it will lead to a poor lubrication performance, and local deformation of the work table, ultimately affects the machining accuracy of the work piece and the service life of the machine tool. For these reasons, this thesis takes DVT1000(10 meter double column lathe) Vertical lathe as the main research object, a method for the combination of fluid dynamics and dynamic mesh technology is adopted to study the transient temperature rise characteristics of oil film in the process of oil film thickness variation, specific research programs are as follows:Firstly, according to the basic principle of the hydrostatic bearing, theory of fluid mechanics, tribology and heat transfer theory, the mathematical model of oil film of hydrostatic bearing is established, including the oil film thickness equation, the oil film flow equation, the oil film temperature rise equation and the oil film control equation. Secondly, according to the engineering practice, 3D simulation model is established by using UG software. The oil film model is divided into grid, according to the boundary condition of the hydrostatic bearing oil film, edit the UDF program, and set the corresponding moving boundary. In addition, based on the finite volume method, the fluid mechanics analysis and dynamic mesh technology are combined. Transient analysis the three-dimensional hydrostatic bearing oil film model is made. In the condition of variable viscosity, the temperature field of oil film is compared and analyzed under different load and rotating speed. Study the oil film thickness reducing, and the temperature change of hydrostatic bearing oil film under variable viscosity, transient temperature rise characteristic of supporting oil film was obtained.Finally, according to the existing equipment to carry on the experimental study of the hydrostatic bearing supporting oil film, the temperature changes of oil film at different load and speed are obtained. Through the comparison and analysis with the theoretical research results, verify the correctness of theoretical research, and it is feasible to use dynamic grid technology to solve the transient solution of static pressure bearing oil film. |
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