METHOD AND APPARATUS FOR DETECTING SURFACE FLAW OF STEEL STRIP

PROBLEM TO BE SOLVED: To provide an optical detection method for precisely detecting the surface flaw of a steel strip in a steel strip continuous transferring line, and to provide an optical detector therefor. SOLUTION: A light source (1) for irradiating the surface of the steel strip, and a line camera (2) for photographing the optical image of the steel strip are arranged so as to be inclined with respect to a steel strip transfer direction, and the line camera (2) is scanned along a scanning line Z (inclined at an angle θ with respect to the width direction of the steel strip) to take in an optical image. As the effect of this oblique scanning, an angle of inclination is formed with respect to a camera scanning direction and a flaw component in surface flaw detection operation setting the fine linear flaw or the like of the same component as that in the width direction of the steel strip, and the data of a normal part and the data of a flaw part are present in image data obtained by one scanning. Under the flaw detection operation of the actual operation accompanied by the variation of base noise (the signal caused by the surface roughness, gloss and other factors of the steel strip), the presence and size of the surface flaw of the steel strip are precisely judged. COPYRIGHT: (C)2008,JPO&INPIT