Research On Automatic Detection Method Of Surface Disfigurement On Steel Pipe

Along with industrial continuous development, the requirement of product's quality is higher and higher, steel pipe take a important part in industrial. With the view of improving steel pipe's product's quality, lowering the labour intensity, and minimizing industrial accidents, we must have an automatic crack testing. Based on the fact that some physic quantum would be changed because of existing defects, non-destructive testing (NDT) could detect the defects. NDT plays a important role of quality controlling and saving raw materials and improve productivity in industry manufacture. NDT is also an important inspection means for the equipment.As one of the most important, fastest and cheapest nondestructive testing methods, Magnetic Flux Leakage technology could be applied in inspection ferromagnetic materials. MFL is also the most commonly used in nondestructive testing and it could find the majority of discontinuities.The main research contents in this paper include:Chapter one:introduces the status quo of non-destructive inspection technology and the methods of non-destructive inspection which is used commonly; Chapter two:based on a brief introduction to the basic principle of MFL, the magnetic leakage field of dotted flaw and crack on spcieman are analyzed using magnetic dipole method. As the previous magnetic dipole theory can only deal with endless defect, this dissertation develops the magnetic dipole theory and applied it to analyze three kinds of common defects and get their three dimensional analytic solution of magnetic leakage field; Chapter three:after analyzing the advantages and disadvantages of different magnetization way, chosen permanent magnets as the excitation source, chosen integrated hall element(CS3503)which have high sensitivity, and high linearity as the sensor, and designed a magnetic device which have simple structure, easy processing, low cost, the magnetic device has a good magnetization effect; Chapter four:have a introductions of data acquisition system design, acquired data with data acquisition card(PCI1711), working out the data acquisition program with Visual Basic6.0, This article exploited the simple, intuitionistic and easily operated man-machine exchanging interface; Chapter five:after working out an easily operated man-machine exchanging interface, did a lot of experiments for roll steel, defect depth influenced on MFL signal; defect width influenced on MFL signal and the lift value influenced on MFL signal, and get the relationship between the parametric defects and the MFL signal. This article also analyzed other factors which affect the test results, Chapter six is conclusions and outlook.