Based On Alternating Electromagnetic Fields Of Steel Surface Defect Detection Systems

At present, industrial production technology of steel plate has become the main method to measure the development of national economy. For the steel rolling, steel, pipe and other safety testing of ferromagnetic materials, the most commonly used technology is nondestructive testing technology. Among them, the alternative electromagnetic detection technology, with simple structure, no need of coupling agent and high sensitivity, has been widely used in the field of nondestructive testing of steel plate.In order to accurately detect the surface crack defects and improve the detection accuracy, this paper studies the technology of magnetic steel. The alternating current electromagnetic detection technology is proposed to detect the steel plate on line in real time. According to the principle of alternating electromagnetic technology, the characteristics of the defect detection of metal plate are analyzed. Explain the relationship between the induced electromagnetic field induced by the alternating electromagnetic field and the induced current on the surface of the steel plate, use COMSOL software of plate test defects of finite element simulation and analysis results.In order to fully prove the reliability of the test based on alternative electromagnetic field, the influence factors of the alternating electromagnetic testing system are studied by excitating frequency intensity, changing the crack size and other conditions. The variation of magnetic induction intensity on the surface and near surface of steel plate was analyzed. The defects of the surface and the near surface of the steel plate were studied by the design and fabrication of the probe of the excitation coil and the detection coil of the alternating electromagnetic detection system. Through the LCD touch screen real time display and storage of the data detection waveform, the detector is used to identify the crack, experimental results good stability, high reliability, more intuitive, accurate and comprehensive get information related to defects. To set up the experimental platform, detect the defects of the steel plate experiment, the experimental results analysis, and improve the experimental equipment.Experiments were carried out to detect the different crack size of steel plate, the amplitude of the LCD touch screen was observed, and the amplitude information of different crack defects was obtained and compared. Experimental results show that under the same condition, with increasing excitation frequency strength, crack length, crack width, defects of the magnetic induction intensity weakened,with the increase of the crack depth, defects of the magnetic induction strength increases, detection depth reached 5-6mm.