Research On Surface Topography Evaluation Based On Wavelet Analysis

The surface topography of micro-parts has a significant impact on its properties, especially friction, bearing and lubrication performance. Reasonable analysis and evaluation are beneficial to its performance and quality. Howe ver, the traditional method is confined in the two-dimensional level, which can`t meet the requirements of modern manufacturing. In order to solve this problem, we developed a software system for 2D/3D parameter evaluation by MATLAB GUI. The software system based on wavelet analysis possesses the interactive, visual, dynamical observation features. The research works as follows:(1) A wavelet model for extracting surface features was constructed by the mathematicmodel of surface topography. The orthogonal wavelet was adopted due to its energy conservation. Sym5 was selected as the optimal wavelet function according to its wavelet reconstruction error. The signal energy of wavelet decomposition layers presents exponential change trend, which determines the number of datum extracted for wavelet decomposition.(2) Based on ISO 25178-2, we investigated the definition and characterization of 24 representative parameters, analyzed the discrete algorithms, discussed and optimized the specific programming method of above parameters. software system for 2D/3D para meter evaluation was developed on GUI, which realized the data loading, feature extraction, 2D/3D parametric calculation, dynamic observation and display of three- dimensional images.(3) The feasibility of discrete algorithms was tested by simulating the typical ideal surface(sawtooth-boss-stairs). By investigating topography data of actual surface(gauge blocks- micro parts), the parameter value which measured by our software system and laser microscopic system were compared, showing numerical error was in the allowable range and demonstrating the validity of our system. The experiments for the effectiveness of 14 parameters were carried out based on gauge blocks. The results show that Sq, Ssk, Sds, and Sdq could be defined as the basic parameter group for evaluating three-dimension topography.