Slab surface defect detection apparatus and surface defect detection method of the slab

摘要

PPROBLEM TO BE SOLVED: To provide a method of detecting a surface defect of a slab for precisely detecting the surface defect such as a blow-hole and a crack produced in the slab. PSOLUTION: In the method of detecting the surface defect of the slab by detecting the surface defect produced in the slab 6 from the data of the unevenness state of the surface of the slab 6 and the surface brightness distribution of the slab 6 both of which are measured by irradiating the surface of the slab 6 with a laser beam 8, the laser beam non-reflecting positions, where the data of the unevenness state becomes a missing value, on the surface of the slab 6 are extracted and the positions and sizes of the low brightness surface parts of the slab 6 determined to be defects in the surface brightness distribution are calculated. When a plurality of the laser beam non-reflecting positions continuously present in the lateral or longitudinal direction of the slab 6 among the laser beam non-reflecting positions coincide with the positions of the low brightness surface parts of the slab 6, the coinciding positions are determined to be defect positions and the sizes of the low brightness surface parts of the slab 6 are determined to be the sizes of the surface defects produced at the defect positions. PCOPYRIGHT: (C)2010,JPO&INPIT