The Application Of Fuzzy Evaluation Method To Estimate The Surface Defect Extent About The Board Strip

As one of the main product forms in steel industry, the cold rolled strips have become the essential material of trades such as automobile, mechanical manufacture, chemical, aviation and spaceflight, shipbuilding and so on. The exist of surface defect reduces the anti-fatigue intensity seriously of accessories, affects the quality of part surface, has effects on using capability and life-span of machines and instruments, and eventually affects the capability and quality of products. So controlling the surface defects reasonably and evaluating the defect degree have important meaning of improving the surface quality and product economic benefit.In this research, aiming at the defect images of gathering welding lines, the author distills the characters of these images with the methods of image swelling, image resuming, image dividing and so on. Then the author calculates the areas of the defect exactly by adopting the method of combining improving Sobel operator with morphological close operation in math.Different defect causes different damage to board strips, the same kind of defect also causes the different damage to board strips under the same areas. Its effect is also determined by the length of the defect. The longer the length is, the deeper the damage is. So we must calculate the length of the defect exactly. Aiming at the defects of the welding lines, the author adopts the method of projection intercept to calculate the length of the defect exactly and effectively.Aiming at all kinds of defects, the thesis uses fuzzy evaluation judgment method, defines five factors such as defect areas, processes the weighted analysis using the analytic hierarchy process, evaluates the degrees of surface defect on the board strip.The thesis uses VC++ to program software. Because the matrix calculation has the character of too many steps, the author makes use of the powerful calculation function of Matlab software to overcome the cockamamie calculation. This makes the evaluation results more reasonable.The thesis bases on the fuzzy evaluation judgment method, analyses all kinds of...