Research On Reliability Modeling Of Hydraulic System Of CNC Machine Tools For Oil Contamination

CNC machine tools,as the "work master machine",which directly reflect the equipment manufacturing level of a country.In the development process of our country machinery industry,domestic machine tools have made very obvious progress in terms of accuracy and speed,but there is still a gap between our country and developed countries in reliability level,which is one of the reasons why domestic machine tools have a low proportion in the international market.Therefore,the reliability technology of CNC machine tools is of great significance to improve the level of CNC machine tools.CNC machine tool is a complex electromechanical-hydraulic system integration,and in the three technical fields of electromechanical hydraulics,the failure of the hydraulic system is the most frequent,and most of the failures of the hydraulic system are caused by the oil contamination in the hydraulic system.There is a certain correlation between the amount of oil contamination and the probability of hydraulic system failure,but the quantitative relationship between oil contamination and reliability is not clear,it is impossible to quantitatively evaluate the reliability of the hydraulic system of CNC machine tools based on the oil contamination.Therefore,it is very necessary to research this aspect to improve the reliability of the hydraulic system of CNC machine tools.The accomplished work in this paper are:(1)A test bench for simulating the operation of the hydraulic system of the CNC machine tool was constructed.Analyzing the working condition of the hydraulic system of the CNC machine tool,designing the hydraulic system test rig based on the characteristics of the hydraulic system of the CNC machine tool,simulating the working state of the hydraulic system of the CNC machine tool under the actual working conditions,and formulate the test operation specification and the operation process,the test design is carried out by the orthogonal test method.(2)According to the operating characteristics of the hydraulic test bench,design the experimental scheme of the hydraulic system under the conditions of environmental influence,and determine the experimental scheme.Collected the oil pollution data under the condition of environmental influence,analyzed the obtained experimental data,established the influence relationship model of environmental influence factors on the hydraulic system oil pollution of CNC machine tools based on BP neural network,and determined by the range analysis method.Correlation of environmental factors on the impact of oil contaminants.(3)The influence mechanism of oil pollutants on the hydraulic system of CNC machine tools is analyzed.The concentration and size distribution of solid pollutants in the hydraulic system are measured.Combined with the relevant parameters of oil pollution,the relationship between solid pollutants in oil and the working state of hydraulic system is explored.Based on BP neural network,the influence model of pollutant factors on hydraulic system is established,which provides modeling basis and reference for the reliability model of hydraulic system of CNC machine tools.(4)Combined with environmental factors and contamination factors,the reliability of the hydraulic system of CNC machine tools is modeled.According to the previous test data and conclusions,under the condition of oil contamination,the stress intensity interference model is introduced to establish a reliability model of the hydraulic system of CNC machine tools for oil contamination,which reflects the quantitative relationship between oil contamination and machine tool reliability.It makes up for the deficiencies of the existing models and provides a basis for improving the reliability of the hydraulic system.Through the research of this paper,the analysis and reliability modeling of the hydraulic system of CNC machine tools provide a theoretical basis and experimental support for improving the reliability of the hydraulic system.