Abstract
The paper presents the development of probe-rotation-type eddy current defect detector for hot rolled round steel bars. On-line defects detection in hot condition was tested by using conventional probe-rotation-type eddy current defect detector with heat shield.
The result of this test was not so good because detection rate of the defects having above 0.3mm depth were only about 48%. Then, these test result were analyzed and main noise factors were extracted. One was the vibration of round steel bars, and the other was their pass line change. Probe rotation speed was increased as the countermeasure for former noise factor, and probe profiling system to round bars was added to probe rotation mechanism for latter one. Consequently, detection rate of the defects having above 0.3mm depth rose to about 100%.
