Latest Advances in Hot Wire Rod Inspection using Eddy Currents

by Jose Bernardez, Sergio Saludes-Rodil, Carlos Rodriguez

Publisher - Isend, Sa., Cartif Foundation.

Category - General Novel

During continuous wire drawing, flaws can appear on the steel wire surface. They can be easily detected through eddy currents inspection technique. Since continuous wire drawing may reach high speeds and huge amounts of results data are generated during the inspection, automated evaluation systems are required. While flaw detection can be solved by an adequate thresholds set, flaw identification can be more challenging. This is because differences between flaws can be small and signal noise may hide them. Moreover, signals can be affected by unexpected disturbances, like are vibrations and temperature changes. Besides this, degradation of process mills rollers can also introduce changes in the eddy signals. These changes can be detected and their properties can be related to the defects, so it is possible to monitor the rollers and assure product quality at the same time. All these problems can be overcome using pattern recognition, machine learning techniques and adequate feature extraction techniques. Algorithms based on them are capable of detecting the flaws in the hot wire and finding out the different flaw types that may exist. Besides this, they can estimate the flaw severity and its position along the wire. These methods, allows the early detection of probes failure and the continuous evaluation of rollers condition. The methodology used follows two main steps: feature extraction in both time and frequency domain and unsupervised clustering.

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