Dissertation > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding process > General approach > Welding defects and quality inspection

Research on the Technology of Online Detecting for Weld Defects of Strip Steel

Author TanShuTao
Tutor PanHongLiang
School East China University of Science and Technology
Course Mechanical Engineering
Keywords weld defect eddy current testing laser outline sensor ANSYS Visual Basic
CLC TG441.7
Type Master's thesis
Year 2012
Downloads 104
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Before hot rolled strip steel enter into pickling line-cold rolling tandem mill, front strip steel and back strip steel need to be welded together to ensure the continuous production of cold-rolled strip steel, however, the weld of strip steel often breaks down when it enters into the rolled mill. There are many reasons that cause the weld of strip steel broken, and the weld defects is one of the main factors. If strictly control the quality of the weld, it will greatly reduce the rate of strip breakage and will improve the production efficiency.the paper presents a solution of the online detecting for weld quality, which include two method, eddy current testing to detect the internal defects of weld and laser outline sensor to detect the surface quality of weld. Research on the theory of eddy current testing and impedance analytical method, utilize eddy current testing, metallographic experiment and X-ray inspecting to detect the weld defects of strip steel, through these experiment to analysis the corresponding relationship between impedance signal and defects, then, prove the reliability of eddy current probe detecting weld. Simulate the 3D magnetic-field of eddy current testing the defect of sheet steel with ANSYS, work out the trend rule between impedance signal and defects parameters, including size, position and type. Based on the research of experiment and simulation on eddy current testing, both of the result, which can guide the field parameters settings of eddy current testing. In the part of laser outline sensor detecting the surface quality of weld, the paper uses VB software to program the function of detecting system, collect a huge amount of data of weld surface morphology, Work out the criterion and threshold value of defects with theory of fracturing mechanics and statistics. Finally, according to the operating condition of online detection method in baosteel company, analysis the reliability of the system.

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