| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of detecting a surface defect of a slab for precisely detecting the surface defect such as slag biting produced in the slab. SOLUTION: In the method for detecting the surface defect produced in the slab from the surface unevenness state and surface brightness distribution of the slab by irradiating the surface of the slab with a laser beam 8 to measure the surface unevenness state of the slab and imaging the surface of the slab to obtain the surface brightness distribution of the slab, the unevenness change ratio in the longitudinal direction of the surface of the slab is calculated by an unevenness change ratio calculating circuit 11, the position and size of the low brightness surface part of the slab determined to be the defect in the surface brightness distribution are calculated and, when the calculated position of the low brightness surface part of the slab coincides with the position of a part where the absolute value of the unevenness change ratio becomes a predetermined threshold value or above, the calculated position of the low brightness surface of the slab is determined to be the defect position of the slab and the size of the low brightness surface part of the slab determined as the defect position is determined as the size of the surface defect produced at the defect position. COPYRIGHT: (C)2010,JPO&INPIT
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