To provide a method with which the edge position of a steel plate can be detected with high accuracy by securing heat radiating efficiency of rolls, while the steel plate is carried under the guidance of the rolls.
On the outer peripheral surface of a bridle roll 21, left and right grooves 22 and 23 which (?!III obliquely extend in the axial direction toward both end sections of the roll 21 from the central part of the roll 21 are formed. Since the states of reflected light rays from the surface of the roll 21 in the axial direction detected by means of a surface detector change as the roll 21 rotates, the waveforms of detecting signals and their differential signals change at every sampling period. Then a histogram is prepared by performing prescribed histogram processing on the detection of the edge position of a steel plate in the width direction, based on the differentiated value of the differential signal. The prepared histogram clearly shows the data required for the detection of the edge position of the steel plate. Therefore, the edge position of the steel plate can be detected accurately, based on the results of the histogram processing.
TANAKA KAZUNOBU
TANAKA KAORU
OTSUKI KEIZO
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