METHOD AND APPARATUS FOR OPTICALLY DETECTING SHAPE OF ROLLED PLATE

摘要

PROBLEM TO BE SOLVED: To detect a shape of a rolled plate wherein influence of a fluctuation in a pass line level can be eliminated without requiring a special sensor when the pass line of the rolled plate fluctuates. SOLUTION: A method for optically detecting a shape of a rolled plate comprises steps of applying light to a rolled plate 2 by a rod-like light source 3 and detecting a shape of the plate based on a displacement amount of a virtual image position of the light source 3 reflected from the rolled plate 2. At this time, a position of an actual detection bright line is corrected to be moved into a state in contact with a reference bright line 32 of the virtual image of the light source 3 at a point without intersecting with the reference line 32 with the minimum movement amount along a longitudinal direction of the plate 2 with respect to the reference line 32 when the rolled plate 2 on the pass line is flat, and the plate shape is calculated after the correction.