| CPC G01N 27/9006 (2013.01) [G01N 27/9046 (2013.01); G01N 27/9093 (2013.01)] | 11 Claims |
|
1. A steel plate high-hardness defects detecting device detecting high-hardness defects of a surface of a steel plate caused by accelerated cooling by generating an eddy current in the steel plate, the device comprising:
an eddy current tester disposed so as to face the steel plate; and
a frame to which the eddy current tester is fixed,
wherein the eddy current tester includes:
a yoke unit having both ends disposed so as to face a steel material, and having a “⊏”-shape, a “C”-shape, a “U”-shape, or a “V”-shape;
a coil unit comprising a coil wound around a central portion of the yoke unit and disposed so as to form an alternating-current (AC) magnetic field in only one direction at the both ends of the yoke unit through the coil and the yoke unit;
an AC power supply unit connected to the coil;
a sensor unit connected to the coil;
a material property determination unit connected to the sensor unit and determining the material property of the steel plate based on a measured signal obtained through the sensor unit and
a lift-off compensation unit connected to the coil, measuring a lift-off compensation value, and providing the lift-off compensation value to the material property determination unit,
wherein the both ends of the yoke unit are parallel,
the AC power supply unit supplies a current of 0.5 kHz to 10 kHz to the coil unit,
the material property determination unit determines the material property in consideration of a distance between the steel plate and the sensor unit, and
the lift-off compensation unit measures a Q factor when a resonant frequency of a current frequency provided by the AC power supply unit is provided, and provides the Q factor to the material property determination unit.
|