| With the rapid development of iron and steel industry, the effect of hot-rolled steel is more outstanding as a main product. However, due to the long metallurgy production and complex process links, surface quality problems, such as surface crack, surface inclusion, oxidized iron, scar and pit, are easy to appear on the surface of hot-rolled steel, which seriously affect the steel material and using performance. In order to improve the performance of hot-rolled steel and make full play of its material function, the size, distribution and type of these defects must be precisely measured, characterized and classified, so as to achieve the quantitative characterization requirements of process optimized control to all kinds of surface defects.Nevertheless, how to obtain the ideal, accurate measurement and classification results of hot-rolled steel surface defects has now became a key problem troubling the numerous material workers and iro n-steel enterprises. And there are no systematic research reports, as well as a satisfied and simple method at home and abroad now. Thus, this paper took the hot-rolled steel surface defects as the research object, innovatively designed a kind of automatic surface defect measurement and classification method and system with an independent intellectual property right.The main research contents and innovative work of this paper are as follows.1) Aimed at the crack defect distributing as complex networks, mixed inclusion and crack on the surface of hot-rolled steel, a new minimum defect branch classification method based on morphological features was proposed, and linear morphological factor was used to precisely classify and region-demarcated the surface defect, in order to insure the effective extraction and accurate calculation of subsequent defect characteristic parameters.2) Aimed at the problem that the size and damage degree could not be measured and characterized by manual model, a new series of characteristic parameters, such as defect equivalent and defect rate, and the special solution formulas were proposed on the basis of minimum defect branch classification method. And then the automatic measurement and numerical characterization of hot-rolled steel surface crack defect were realized.3) Aimed at the other heterogenous defects, excepting typical crack defects on the surface of hot-rolled steel, like inclusion, oxidized iron, scar and pit, which could not be quantitatively characterized, a new irregularity area algorithm based on the grayscale difference of defect image, and the corresponding solution formulas were proposed in this paper, so as to provide a new evaluation method to the quantitative characterization of hot-rolled steel surface heterogenous defects.On the basis of above research work, the application and results of massive engineering examples show that, the surface defect measurement and classification system proposed in this paper could realize the automatic measurement and precise characterization of hot-rolled steel surface defects efficiently and conveniently, and the measurement precision and calculating speed can be up to ±0.001μm and 20 ~ 30 s, which provided a reliable basis to the quantitative analysis of hot-rolled steel surface quality. In addition, this method has a good universality and can be applied to the measurement and characterization work of complex surface defect s in other engineering fields, such as material, highway and construction. |
