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Method and arrangement for detecting surface and structural defects of a long moving product

  • US 7,970,202 B2
  • Filed: 06/12/2006
  • Issued: 06/28/2011
  • Est. Priority Date: 06/14/2005
  • Status: Expired due to Fees
First Claim
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1. A method for detecting defects of a product moving in a rolling mill, said method comprising the steps of illuminating the moving product at least once with a light source, forming by scanning a first image of the moving product as observed in a first spectrum band of light, producing from a first image of an observation area of the product a first digitized luminosity distribution of said area, using the first digitized luminosity distribution of the observation area of the product to detect the presence and location of any defects in said area, classifying suspect zones into at least one category of defects or non-defects by comparing morphological and/or photometric characteristics of said suspect zones with morphological and/or photometric characteristics of known defects and of known non-defects held in a pre-established database, applying said method to a product moving in a hot-rolling installation and spontaneously emitting a light radiation in a spontaneous emission spectrum including the infrared, said illuminating step being implemented by illuminating the moving product with a visible light source emitting at least outside the spontaneous emission spectrum, said scanning forming step comprising forming at least three images of the same observation area of said product in three respective non-contiguous spectral bands of which a first band lies at least in the infrared, a second band at least in the red, and a third band at least in part of the visible spectrum outside the spontaneous emission spectrum, said producing step being at least implemented on said three images to provide at least three respective luminosity distributions digitized over several bits performing a detection and extraction operation of suspect zones on the digitized luminosity distributions and said classifying step comprising classifying at least the suspect zones extracted from the digitized distributions into at least one category of inner defects of the product, surface defects of the product, and non-defects of the product at least by comparison of the morphological and/or photometric characteristics of said suspect zones and scattering of said suspect zones among the digitized distributions with the morphological and/or photometric characteristics and scattering among corresponding digitized distributions of known inner defects, known surface defects and known non-defects held in said pre-established database.

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