Research On Steady-State Control And Tribological Characteristics Of Oil Film In Hydrostatic Bearing

With the upgrading and transformation of the manufacturing industry,the processing of heavy-duty parts is becoming more and more diversified,resulting in the deviation of the center of mass of the workpiece from the center of the worktable,the worktable bearing the eccentric force,the unstable thickness of the oil film during the operation,thus reducing the processing quality of the workpiece,and even causing the oil film to become thinner,and eventually dry friction.As the core part of heavy vertical machining equipment,it is necessary to study the oil film control scheme and Simulation of hydrostatic bearing under off load condition,and analyze the oil film tribological characteristics after control.First of all,by referring to the domestic and foreign references and comparing the research status of hydrostatic bearing at home and abroad,the structure and working principle of hydrostatic bearing are described,and the control equations of oil film flow,bearing capacity,oil film thickness and oil film temperature rise are established under the condition of quantitative oil supply.Secondly,the oil film thickness detection method is compared and studied,the oil film thickness detection scheme of eddy current displacement sensor is drawn up,the oil film thickness signal noise filter is designed,the signal filtering simulation is carried out by using Matlab/Simulink,and a new displacement sensor installation method is proposed.Determine the oil film thickness control scheme in three separate zones,and select the key hydraulic components.Establish the mathematical model of each part of the oil film thickness control system,determine the relevant control parameters,and complete the derivation of the oil film thickness transfer function.The stability of the system is analyzed,the single channel oil film thickness PID controller is designed,and the oil film thickness fuzzy self-adaptive PID controller is designed by combining the fuzzy control theory.The PID controller and the fuzzy self-adaptive PID controller are simulated respectively.Step interference isadded to the simulation model,the control speeds and control errors are compared respectively,and the robustness is analyzed.Finally,12 oil films in the three channels are simplified into three circular array oil films,and the tribological characteristics of the controlled oil films are studied by hydrodynamics simulation.The software Solidworks,ICEM CFD,FLUENT and CFD-POST are used to model,mesh,solve and post-processing the oil film respectively.The tribological characteristic parameters and their influence laws of the oil film average pressure,maximum pressure,maximum dynamic pressure,average dynamic pressure,average temperature and maximum temperature at different load offset sizes and rotational speeds are studied.The tribological characteristic parameters of the controlled oil film and the uncontrolled oil film were compared,and the reasons were analyzed to provide the basis for the further optimization design of the hydrostatic bearing.