Modeling Methods Research On Oil Film Control Of CNC Machine Hydrostatic Guideway

With the development of modern industry and manufacturing industry,the tradition machine can't achieve some processing requirement yet,and the common guideway unable to keep pace with the development trend of high-speed,heavy-haul and high precision processing.So,more and more CNC machine appear at the processing plant of factory.And the hydrostatic guideway are become widely used in the lathe because of its superior performance.Controling of oil film stiffness has great effect on the CNC machine,so intensive research on oil film thickness control of hydrostatic guideway has great significance.This text focus on oil film thickness control,and the modeling methods research includes guide rail structure,hydraulic system,oil cavity structure and its flow field,and the control system of oil film.Firstly,the basic theory of lathe hydrostatic guideway was introduced.Then,the overall scheme on oil film thickness control of CNC machine hydrostatic guideway was confirmed.Designed the structure of guide rail,and selected the components of hydraulic system.Checking computations were operated on the hydraulic control system.And the simulation analysis of hydraulic system was carried out by AMESIM software.Established the 3D model of oil pocket,and the model can be meshed by GAMBIT software.After meshed,the model will be imported to FLUENT software and the simulation analysis of the model was carried out.It got the static pressure distribution and velocity distribution.According to the simulation results,summarized the law of oil pocket pressure distribution by the numerical simulation method.Calculated the total force of oil in the guide rail,established the flow equation and force equation of the guide rail,and linearized the two equations.Finally,the mathematical model of the control system was established,and the parameter of the model was selected.Solved the state space equation of control system,and analyzed the stability,controllability and observability of the control system by modern control theory;Established and simulated the model by PID controller,adjusted and.obtained the optimal parameter,and the performance of control system can be optimized ulteriorly.Builded the oil film thickness control bedstand of hydrostatic guideway,tested the oil temperature and pressure of the hydraulic system,finished the test of performance of the bedstand.Through the research on this topic,the hydraulic system of CNC machine hydrostatic guideway was designed.The simulation analysis of hydraulic system was carried out,and the simulation analysis on pressure distribution of oil pocket was also carried out.The simulation results basically meet the actual situation.Established the mathematical model of the control system of the oil film thickness,and searched the control characteristic of the system.Applied the PID control into the control system,the characteristic was good,and optimized the control system by the method of pole assignment.