Applied Research Of Triaxial Sensors On Acquisition Of The Steel Tube Defects Signals

Among the nondestructive test methods of steel pipes, the magnetic fluxleakage inspection technology is widely used in the steel pipes defect detection insafety assessment of production and operation of the steel pipes because of its highdetection efficiency and good reliability.Steel pipe leakage magnetic detection system includes magnetic flux leakagesignal acquisition, signal processing of magnetic flux leakage and defectidentification. And the magnetic flux leakage defect signal acquisition is a key partof the system. Sensors of signals acquisition used in domestic and foreign advancedmagnetic flux leakage inspection system are one-dimensional sensors, each collectsone direction of the magnetic field. Make the pipes detect the horizontal andvertical components of the magnetic flux leakage through the axial andcircumferential magnetizers in turn, which can determine the basic defect lengthand depth information, but it is difficult to accurately determine width informationof the defect. This kind of magnetization is relatively complex, and thediscriminant accuracy of the signal parameters is to be improved.The subject is from the study of magnetic flux leakage inspection of steel pipe,using the triaxial sensor detection will be able to get the three-dimensionalcomponent of the magnetic flux leakage signal. The significance of thethree-dimensional magnetic flux leakage inspection: To improve the data detectionefficiency and reduce the complexity of the magnetizing device; use ringcomponent of magnetic flux leakage signal to determine width information of thebasic defect. The combination of the three-dimensional components of the magneticflux leakage signals to come to the defect size data to improve the discriminationaccuracy of defect parameters.The main contents are as follows:1. Based on three-dimensional magnetic flux leakage detection principles ofsteel pipes, firstly research on the three-axis magnetic sensor detection technologytheory, then analyze the probe excitation mode.At last analyze the excitationmagnetic circuit.2. Application of finite element analysis software to analyze three-dimensional component of the leakage magnetic field. Get three-dimensional magnetic fluxleakage signal of pipe cracks and holes defect by simulation,and focus onanalyzing the relationship between the three-dimensional component of the leakagemagnetic field and the defect parameters. The results show that: horizontal, verticaland ring component of the magnetic flux leakage signal has fitting relationship withcrack length, depth and width, then the crack parameter information basicallydetermined by calculating; Pore diameter has a linear impact on the ring componentof the leakage magnetic, which can be used to determine the pore diameter.3. Design three-dimensional magnetic flux leakage signal acquisition systemof pipe based on Hall sensors. Steels rotate in place combined with the probe linescanning mode, using a magnetized device to complete the scanning of the steeltube defects, reducing the complexity of the equipment. Design three-axis sensors,probes, magnetizing devices and magnetic flux leakage signal processing circuit.4. Make experiments on the acquisition device of three-dimensional steel pipeleakage magnetic to determine the experimental test program, respectivelyproducing two different sets of artificial cylindrical flaws. Make magnetic fluxleakage data acquisition experiment of steel tube defects and obtain threedimensional magnetic flux leakage test data, then analyze the test results.Finally summing up the work, and prospecting on further study of the triaxialsensor technology.