Study On Stitching Techniques Of Large-scale 3D Topography Of Grinding Wheels

The grinding wheel is widely used in precision grinding, the surface topography of which has an important influence to the quality of machined workpiece surface. Therefore the surface evaluation parameters of the wheels will help control quality of products and optimize the grinding process if the3 D surface topography information of the grinding wheel can be obtained. The vertical scanning white light interferometry, as a non-contact measurement method, has such advantages as high precision, large measurement area and non-fuzzy phase. However, it’s difficult to gain a surface topography of grinding wheel in a wide range by one measure because of its small field of view. So it needs a rapid and accurate grinding wheel stitching method to solve the problem. In this paper, the fuzzy PID algorithm is used to control the equipment and acquire 3D data of grinding wheel topography. The particle swarm optimization(PSO) algorithm is utilized in the rough matching; the iterative closest point(ICP) algorithm is adopted in the fine matching; and a linear weighted method is used in the integration. Evaluation methods of 3D topography stitching quality of grinding wheel are studied. The theories and experiments indicate that the method adopted can meet the demands of high precision and high efficiency in the surface topography stitching process.The main contents are as follows:(1)First, the white light vertical scanning interferometry and other measurement techniques for the grinding wheel topography measurement were reviewed. The principle of white light vertical scanning method used in this paper was given. The current situations of 3D registration technologies at home and abroad were introduced.(2)Second, the white light vertical scanning interferometry system was built,which included a scanning system in vertical direction, two displacement systems in horizontal directions and one rotation system. The components ofeach system and their performances were described in detail. The errors lying in the horizontal direction systems were calibrated, and a closed-loop fuzzy PID control strategy was proposed to eliminate the errors.(3)Third, some stitching strategies for surface topography of grinding wheel were analyzed, and a stitching method for surface topography of grinding wheel, which needed some overlapping area, was proposed. And this method was realized by some steps including preprocessing, rough matching,precise matching, integration, and so on. A PSO algorithm was utilized for rough matching; an ICP algorithm was utilized for precise matching; and a linear weighted method was utilized for integration. With the help of these methods, a large area of 3D surface topography of grinding wheel was achieved, and a quality evaluation method of 3D surface topography stitching of grinding wheel was researched.(4)Finally, the methods were verified by experiments using standard samples and PSO parameters was analyzed. The stitching algorithm was applied to obtain a large surface topography of grinding wheels, and some stitching evaluation results were given.