The Simulation And Experiment Research Of Pressure Fluction For Ultra-precision Fly Cutting Machine Liquid Static Pressure Guide

With the development of ultra-precision manufacturing,more and more precision optical materials are widely used in space science,national defense and civil field,in which KDP(potassium dihydrogen phosphate)is widely used in inertial confinement laser fusion,strong laser weapon and other laser systems due to its excellent material properties.The key technology of the machining of high quality is KDP fly cutting machines with excellent machining properties.However,there are many influence factors for KDP fly cutting machines,such as the spindle's rotation accuracy,the positioning accuracy of the static pressure guide and the rationality of the structure of the machine structure.The stability of the output pressure of oil supply system the premise of the positioning accuracy of the static pressure guide.If there is pressure pulsation exists in the hydrostatic guideway for pressure source,the oil film pressure between guide bearing surface will be changed.Thus,the rolling guide and static guide will be out of shape due to the change of oil film pressure and then influences the stiffness,straightness and other properties of the guide.However,few studies have been done on this field.This paper will start with the pressure pulsation in the hydrostatic guideway for pressure source and then conduct the study.Start from the source of the pressure pulsation of the hydrostatic guideway,the theoretical analysis of the main components that include the internal and external rotor cycloid pump,overflow valve,orifice and energy accumulator in the hydraulic circuit was conducted.The entire hydraulic circuit and the influence factors of pressure pulsation in the hydraulic circuit was analyzed by the fluid electrical equivalent circuit theory.The relationship between the pressure of the motion guide and static guide and the thickness of oil film was analyzed theoretically and the expression was setup.The characteristic curve of pressure pulsation was obtained by setting up the CFD simulation model of pump and flood valve in the hydraulic circuit.The sub-model of orifice and energy accumulator was setup in Amesim hydraulic system simulation software and the model of the entire hydraulic circuit was setup.The parameters of the sub-model in the hydraulic circuit was set according to the pressure pulsation curve of pump and valve obtained before.The situation of pressure pulse in the hydraulic circuit and the influence factors of pressure pulsation in the hydraulic circuit were calculated and analyzed respectively.The experiment test of pressure pulsation in the hydraulic circuit was conducted to analyze the error between experimental results and simulation results.The unidirectional fluid-solid coupled model of the hydrostatic guideway was setup.The change of fluid domain under different pressure pulsation and the situation of the deformation of rolling guide was calculated according to the fluid-solid coupled model that put the pressure measured by experiment test as boundary conditions.Then,the displacement of the middle point of the left motion guide was obtained theoretically according to the expression of the sickness of oil film.The actual displacement of the middle point of the left motion guide was measured by experiment test and then the theoretical results and experimental results were compared to analyze the factors that cause the difference.Finally,t he fly-cutting experiment of KDP crystal was conducted to compare and analyze the improvement of the material's surface quality.