Research On Three-dimensional Roughness Assessment Of MWEDM Surface Based On Wavelet Analysis

Micro Wire Electrical Discharge Machining, with its non-contact and easy processing ofhigh aspect ratio micro and small components of complex shapes, determines its dominantposition which can not be replaced in the micro-nano manufacturing population with verysmall scale and very high precision. However, up to now, according to the magnitude of thetwo-dimensional roughness Height parameters combined with the Hybrid parameters，theassessment of surface quality is made. Micro-WEDM surface is isotropic type, andtwo-dimensional roughness made a lower precision assessment of the surface of such type.Spatial distribution characteristics of the micro-WEDM surface structure determine that it ispossible to get accurate characterization of surface roughness only in the three-dimensionalrange. Domestic and foreign scholars focus on the relationship between surface physicalproperties and the discharge parameters, while there has fewer research of three-dimensionalroughness, what’s more, there is no in-depth study on surface morphology structure andoverall geometry which is the basis of three-dimensional roughness. Therefore, this paperstudies about statistical characteristics of the spectral distribution of the surface of structuralcomponents and the surface of three-dimensional roughness assessment by scanning probemicroscopy of micro-WEDM surface of microscopic three-dimensional morphology.Firstly, Mathematical morphology decomposition of surface structure is adopted and thesurface of convex peak is Extracted and Convex peak geometry and the variation is studied aswell. Micro-WEDM surface height and the cumulative probability of the profile heightdistribution histogram are found with stochastic theory, which indicates that Micro-WEDMsurface approximately obeys Gaussian distribution. Power spectral density function is used tostudy of Micro-WEDM surface spectral characteristics with such the result thatMicro-WEDM surface belong to the isotropic surface. And direction of the surface such as ahigh degree of homogeneity and slope homogeneity is described quantitatively with surfacespectral moments. Compared with the cylindrical grinding surface, Micro-WEDM surface hasgood high degree of homogeneity and slope homogeneity.Wavelet analysis method is used to extract the Micro-WEDM three-dimensional surfaceroughness assessment datum. The orthogonal wavelet as the datum extracted wavelet filter is chosen, because of orthogonal wavelet energy conservation features. By waveletreconstruction error of measurement of three-dimensional morphology of the surface, in orderto determine sym5wavelet for the Micro-WEDM surface datum to extract the optimalwavelet basis; by way of wavelet decomposition layers of signal energy to the law ofexponential change to determine the datum extracted the number of wavelet decomposition.Comparative analysis is made of Wavelet assessment of baseline and Traditional filter todetermine the baseline and we have the result that Wavelet assessment of cause’s separation ofroughness from the surface structure of the signal, there is no approximation error, and doesnot depend on the size of the assessment area.Micro-WEDM surface of three-dimensional roughness assessment parameters is availabefrom the surface structural characteristics and features a total of five aspects. Morphologychanges in the surface of the wear process by numerical simulation of Micro-WEDM,statistical parameters of the analysis of amplitude with the variation of the wear process, thesurface of the run-in period interval; given height distribution shape parameter inMicro-WEDM surface assessment new characterization significance. Three-dimensionalroughness spatial parameters of the algorithm is Improved, directly through thetwo-dimensional autocorrelation function characterization of surface texture characteristics ofMicro-WEDM the complexity of the surface two-dimensional correlation spectroscopy crosssection roundness characterization of surface texture, the main cross-sectionradius direction tocalculate the main direction of the surface texture. Based on the idea of differential geometryof surfaces, algorithm of curvature in the Hybrid parameters is improved, and micro-WEDMsurface roughness of structural features is combined and consequently a new characterizationparameters is proposed which is the Gaussian curvature of the surface peak Sgc. Surfacesupport rate curve through different processing energy of Micro-WEDM, combined with theresults of numerical simulation of surface wear process, determine the height of the supportrate of10%and80%of the corresponding support as the two cut-off value of the surfacefunctional areas, surface together with the support rate curve is divided into four functionalareas, the main volume parameters9function of the three-dimensional roughness Functionalparameters. Watershed segmentation method to determine the number of surface peaks, andthen established on the basis of four characteristics of the three-dimensional roughnessFeature parameters.22three-dimensional roughness parameters is finally proposed to complete a comprehensive assessment of micro WEDM surface.Standardized the micro WEDM surface three-dimensional roughness assessment system,including10terms and definitions,4geometrical features,4typical algorithms of parameters,11graphic representations. Exploratory study is made about the micro WEDM processingthree-dimensional surface roughness assessment sampling area and assessment area, it isrecommended that the three-dimensional micro WEDM surface roughness using a circularsampling area within each sampling area contains at least three peaksor pit features, anassessment area within a diameter range contains at least five sampling area.