SURFACE FLAW DETECTION DEVICE, SURFACE FLAW DETECTION METHOD, AND MANUFACTURING METHOD FOR STEEL MATERIAL

摘要

A surface flaw detection device according to the present invention optically detects a surface flaw in a steel material, said surface flaw detection device being characterized by having an irradiation means that uses at least two differentiable light sources to irradiate illumination light on the same detection target site from different directions, and a detection means that detects a surface flaw at the detection target site by acquiring images produced by the reflected light of each illumination light and carrying out differential processing between the acquired images, and further characterized in that an optical system satisfies a predetermined condition. As a result, it is possible to accurately distinguish a surface flaw from scale/an unharmed pattern.