| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect the amount of sagging of a steel plate edge. SOLUTION: With eddy current sensors 1 and 2 with an E-type core, the eddy current sensor 1 is arranged at a position for generating a thickness change due to the generation of 'sagging' of a steel plate L, and the eddy current sensor 2 is arranged at a position deviating from an edge in the direction of plate width toward a direction that orthogonally crosses the edge and is arranged at a position for preventing the thickness change from occurring due to the generation of the 'sagging'. Detection signals SEG and SIN of the eddy current sensors 1 and 2 are converted to distance DEG and EIN from each of the eddy current sensors 1 and 2 to the steel plate L to calculate the differenceΔD. When no 'sagging' is generated, the differenceΔD becomes nearly zero sic the thickness of the edge part of the steel plate L and the inner position is the same. On the other hand, when 'sagging' is generated, the distance DEG becomes large and hence the amount of saggingΔD becomes large since the thickness of the inner position is invariable but the thickness of the edge part becomes thin. When the amount of saggingΔD exceeds a limit value Dmax, it is judged a trimmer blade needs to be replaced, which is outputted to an output device 7 for reporting to an operator.
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