METHOD FOR DETECTING FLAW ON SURFACE OF STEEL MATERIAL IN HOT ROLLING

摘要

PURPOSE:To prevent excessive detection and erroneous detection and to detect harmful flaws and the like in the surface of the steel product correctly in accordance with required categories, by setting a detecting level which exceeds the variation in noise level that is determined in response to the machining amount of the steel material in the direction of the width of the steel material. CONSTITUTION:The surface of the steel material is quickly heated by an induction coil and the like. Then the surface temperature is measured by a thermometer. Since the steel surface faces a heater with a minute gap being provided, the flatness of the steel material largely affects the range and accuracy of checking. Meanwhile, when the steel material is rolled, the tip of the rolled steel is often bent upward. Therefore, when the conveying direction forms the first pass of the rolling, the rolling of the steel material is finished in an even number of passes and supplied to an apparatus next to the rolling mill; or the steel is supplied with the last pass as a shape control pass. Then the method can be applied to the entire area of the steel material to be measured.