We have developed a technique which can accurately read engraved letters for controlling physical distribution on a bloom of temperature of 800 and installed it in producing line of our steelworks. In our target producing line, physical distribution is controlled by visually confirming tracking information about a computer system for uniformly controlling the works physical distribution and engraved letters on manufactured and conveyed blooms (Depth 0.3 mm, Letter width: 10mm, Height: 20mm, and so on).
However, there is a problem that different materials could possibly flow out because of human errors caused by the work depending on human eyes. For solving the problem, we have developed the measuring system in which a two- dimensional laser distance meter with an optical filter and an athermanous filter moves in the direction of rows of engraved letters over the edge of stopped bloom and measures the surface of the bloom.
Engraved letters can be recognized and read by means of our developed processes including distinction between the surface and the engraved letters part by characteristics that the distance of the part of engraved letters from the laser distance meter is longer than that of the surface of the bloom, extraction of just engraved letters by binarization process, and pattern matching process of learned letters. Additionally, we have improved reading rate of letters to 95 % and prevented different materials from flowing out by reciprocating laser distance meter over the surface of the bloom.