Study On 3D Image Detection Techniques For Surface Topography Of Micro-milling Parts

In view of the problem that it is difficult to detect and evaluate 3D surface topography of micro-milling parts by traditional two-dimensional detection methods,this paper analyzes the development status of 3D topography detection methods at home and abroad,studies the detection and evaluation methods for three-dimensional surface topography of micro-milling parts by using image detection techniques.In order to realize the in-situ detection of micro-milling parts,three-dimensional surface detection system was designed,which can be integrated with the machine tool.The system includes a microscopic imaging unit,a motor drive unit,a lighting unit and a 3R fast change unit.Microscopic images of micro-milling parts were captured in their position by this threedimensional surface detection system.And the local variance information entropy image clarity evaluation operator was proposed to realize the fast automatic focusing of 3D surface topography detection system.In this paper,an optimized 3D surface topography detection algorithm that combined Shape From Shading algorithm(SFS)with Depth From Focus algorithm(DFF)was studied.This two algorithms were combined by wavelet transform to supplement the missing height information and surface detail information of DFF algorithm.The surface detection verified experiment of 7075 aluminum alloy after micro-milling was carried out and the surface topography detection result was compared with that from laser confocal microscope.The result shows that the 3D morphology of micro-milling surface can be accurately detected by using the 3D topography detection system and the detection algorithm designed in this paper.Finally,the 3D surface topography was evaluated.According to the ISO-25178-2 International Standard,the three-dimensional evaluation parameters for surface topography of micro-milling parts were summarized,and the least square datum plane was used as the benchmark surface to evaluate the surface topography of micro-milling parts.The 3D roughness evaluation parameters were calculated and the 3D profile of micro-milling surface was analyzed and evaluated according to the calculated results,which realized the in-situ detection and evaluation for three-dimensional surface topography of micro-milling parts.