Three-dimensional Valve Fitting Surface Profilometer Of Diaphragm Gas Meter

Diaphram gas meter is a specialized flow meter measuring the volume offuel gas. Valve bonnet and valve seat are the key parts of diaphragm gas meter, whichcompose the main factors of its metering error. Currently, the gas tightness detectingways of valve fitting face are direct observational method and pneumatic pressuremethod, but with bad accuracy, low efficiency and lack of science. In order to solvethe situation on the inadequent means of detecting the tightness of gas valve, surfacetopography method was adopted. Main research contents are as follows.Firstly, the relationship between gas tightness and surface roughness of valvefitting surface was discussed. The fast convolution algorithm of Gaussian filter wasderived. The advantages and disadvantages of linear Gaussian filtering, regressionGaussian filtering and robust Gaussian filtering were compared. The evaluationparameters of two-dimensional surface roughness were studied, and the relevantevaluation parameters of three-dimensional surface roughness were explored.Secondly, regarding the inherent disadvantages on measuring roughness ofcontact method, the non-contact method of measuring roughness of gas valve fittingsurface was proposed. The high-accuracy2D laser displacement sensor was selected.And we designed the high precision two-dimensional positioning stage and thecolumn bracket, driven by servo motor and stepper motor respectively.Furthermore, the software system of three-dimensional valve fitting surfaceprofilometer of diaphragm gas meter was developed. With the means of VC6.0calling the relevant functions from dynamic link library, the two-dimensional profiledata acquisition of sensor was realized, the double closed-loop feedback control oftwo-dimensional positioning stage and the smooth lifting of column bracket wereachieved. This software system has the features of profile acquisition, data storage,surface topography mapping, report generation and so on. And it can achieve theevaluation of two-dimensional and three-dimensional roughness parameters of valvefitting surface. Finally, surface roughness of the qualified and unqualified valve bonnets ofdiaphragm gas meter was measured, the threshold values of Ra and R3a are1.274mand1.140m respectively, which provides a scientific basis for evaluating the gastightness of valve bonnet working face in a quantitative way, and has a guide role indetecting the gas tightness of industrial parts at the same time.