| 摘要 |
<p>1. Method of detecting surface defects on metal products (6) such as slabs, blooms, billets and beams, during rolling, continuous casting or otherwise, in which a number of rows of photosensitive detectors are used to scan the surface of the said products (6) and to measure remotely by means of a temperature-measuring device the temperature of clearly defined areas of the afore-mentioned surface, characterized by the fact that at all times during the said scanning operation at least one pair (11, 13) of photosensitive detectors are used to measure individually and simultaneously the radiation emitted by two areas of different size of the said surface, one of these two areas, termed the "confined area" (1), being contained within the other area, termed the "wide area" (2), also characterized by the fact that the signals representing the temperatures of the aforementioned confined and wide areas (1, 2) are combined and that this information is used to establish a signal known as the "defect signal", and further characterized by the fact that the existence in the confined area (1) of a shell or a crack is revealed when this defect signal is either below or above a reference signal determined previously according to the nature of the metal product (6) and the operating conditions.</p> |
