Analysis And Applications On Hydrostatic Rotary Table Of Heavy-duty CNC Gantry Machine

Heavy and super-heavy machine is widespread applied in power, AerospaceEngineering, Shipbuilding, Metallurgy and Mining. But the design and analysis aboutheavy machine is far from perfect. Hydrostatic rotary table is important part of heavymachine which is touch to the carrying capacity and working accuracy. This article isaim to analyze the carrying capacity of heavy machine under the context that thecoupling influence of deformation and oil pad supporting force is not ignored. Theinfluence of supporting point distribution and number, temperature rise, oil filmthickness difference is concerned in the analysis. The achievement can providereliable carrying capacity of machine and guide the distribution of supporting pointand the design of oil pad.The global structure and support principle of hydrostatic rotary table isintroduced at first. Then the design method of hydrostatic oil pad used in rotary tableis discussed. The supporting force of oil pad is calculated by theoretical method andsimulation, verifying the feasibility of Fluent on oil film simulation. The nonlinearspring element is designed to replace the hydrostatic oil film based on the hydrostatictheory and the finite element model of hydrostatic rotary table is established whichcan used to consider the coupling influence of deformation and oil pad supportingforce. The supporting force of oil pad is calculated under different location andnumber of supporting point, the carrying capacity of worktable can be achieved underthe constraint of maximum pocket pressure. And the best radius and number ofsupporting point is achieved.In order to analyze the influence of temperature rise, the temperature rise of oilpad is calculated. The variation of oil viscosity and oil film thickness under theinfluence of temperature rise is analyzed. The temperature rise is set as boundarycondition to simulation the temperature field of rotary table, and then the temperaturefield is considered as volume load to calculate the carrying capacity of worktable. Theinfluence rule of temperature on the carrying capacity is achieved.The initial parameters of nonlinear spring can be set to different values tosimulate the different film thickness of oil pad due to the guide manufacture error andoil pad assemble error, and then its influence to the carrying capacity of worktable can be analyzed. The initial film thickness of each oil pad can be achieved by each oil padpressure measured by experiment. Then the oil pad pressure under different load issimulated and measured. The contrast of experiment and simulation result proved theFEM of hydrostatic supporting system is correct.