针对金属板表面缺陷的检测问题,探讨了低频电磁检测原理和检测方法,提出了金属板的低频电磁检测方法.分析了激励信号频率对漏磁场磁感应强度的影响;分析了不同尺寸缺陷和提离值对漏磁场磁感应强度的影响.采用制作的激励线圈、检测线圈进行低频电磁检测试验.结果表明:激励频率为20Hz时,检测信号幅值最大;随着缺陷深度的增加,检测信号幅值增大;随着检测线圈提离值的增加,检测信号幅值减小.

Aiming at the detection of surface defect of metal plate,the low-frequency electromagnetic detection principle and detection methods were studied,and low-frequency electromagnetic detecting method for metal plate defect was proposed.A low frequency electromagnetic detection model and three-dimensional simulation was established.The effect of excitation signal intensity and excitation frequency on leakage magnetic field magnetic induction intensity was analyzed.Influence of different sizes of defects and lift-off on the leakage field magnetic induction intensity was also analyzed.Excitation and detection coil was produced,and experimental study of low frequency electromagnetic detection was performed.Experimental results showed that,when excitation frequency was 20Hz,the detected amplitude of the signal was maximum.With increasing depth of the defect,the amplitude of detection signal increased.And with the increasing in lift-off of detection coil,detection signal amplitude decreased.