Research On Geometry Measurement Theory And Geometry Parameter Measurement Technology Of Valve Assembly

As a key component of hydraulic servo control system(including mechanical hydraulic and electro-hydraulic),servo control valve is usually an amplification mechanism.It is widely used in aviation,aerospace,heavy weapons,construction machinery and other control fields.Its performance affects the control function,control precision and response speed of the whole system.As an automatic control system,the servo valve proposed in this project is the main component of the combined cylinder,which is the key component of the steering hydraulic system of a certain vehicle.The existing problems directly affect the function of the combined cylinder,thus affecting the safety of vehicle steering and driving.At present,the equipment users have a big response and need to be solved urgently.The main problem is that the O-ring of the spool will have different degrees of eccentric wear after the spool works for a period of time(within the life cycle of the product),resulting in the deformation of the throttle edge and serious oil leakage.In this regard,the enterprise has always attached great importance to organizing relevant management,design,process and field work personnel for many times to carry out analysis,test and technical breakthrough,but it has never fundamentally solved the problem.The main reason is:the quality inspection of the valve,especially the inspection of the geometric parameters of its inner surface,is lack of necessary and effective measurement and detection means.The measurement of geometric tolerance on the inner surface of deep hole is a technical difficulty in the field of geometric error measurement of parts at present,and few references about precision measurement methods or technologies can be retrieved.Based on this,the main research contents of this paper include:(1)According to the requirements of geometric dimension and tolerance items in the random control valve,this paper designs three experimental measurement schemes,which are CMM,precision rotary measuring device and general measuring instrument,to collect,measure and evaluate the experimental data of 12 sets of random control valve components,and randomly select a set of random control valve components to be measured by the Provincial Institute of metrology,Through a variety of methods and angles comparison measurement,the purpose is not only to calibrate and verify the developed data processing software and desktop measurement device,but also to ensure the accuracy and objectivity of the measurement results.(2)According to the requirements of different experimental schemes,the least square mathematical evaluation model of roundness,cylindricity,coaxiality and perpendicularity based on rectangular coordinate measurement method and polar coordinate measurement method is established.In order to verify the correctness of the theoretical evaluation model,the simulation analysis model of the evaluated contour is established and verified by MATLAB software.(3)This paper analyzes the influence factors of the theoretical error evaluation model,including the eccentricity,installation tilt,rotation error and so on,and puts forward a new method to separate the rotation error of the measurement system,and establishes the theoretical mathematical model of the corresponding error separation.(4)The idea of building modular geometric error measurement device platform is put forward,using the most common instruments and equipment to realize the construction of high-precision measurement rotary device.At the same time,the modular,systematic and standardized configuration of data acquisition and control system is carried out.(5)A set of virtual instrument evaluation system and servo unit control system are designed by using LabVIEW and graphical programming language.The functions of original sampling data collection,transfer,evaluation,storage and query are realized,and the shape characteristics of the measured contour can be characterized by the display of graphics window.Through the research of this subject,the measured aperture is less than Φ 12mm,hole depth more than 25mm and 37mm;Or the measured aperture is less than Φ The measurement of deep holes with 30mm and hole depth exceeding 52mm is difficult.In the process of project research,the influence of the change of sampling points on the measurement and evaluation results of geometric errors is explored;The uncertainty of measurement of CMM is put forward and verified.Finally,the theoretical support or rationalization suggestions are given for the rationality of precision design of the valve assembly.