Method and apparatus for detecting flaws on metallurgical products

摘要

(57) [Summary] The surface is illuminated with two coherent light plane beams (13, 14) having wavelengths near the visible spectrum edge to detect flaws. The two beams are produced, for example, by laser diodes (11, 12) and form a single light trajectory (T) on a single plane (P) substantially perpendicular to the product surface (2). The beams are oblique to each other at approximately equal angles of incidence (i). The illuminance along the trajectory (T) is measured along the direction (18) orthogonal to the surface (2) at, for example, the linear array camera (17) at the above wavelength. A local and rapid decrease in illuminance indicates the presence of a wound. It is used to detect small holes and scratches on metallurgical products obtained by continuous casting.