Liste des communications
Surveillance des ventilateurs de dépoussiérage en utilisant les cartes auto-organisées
La disponibilité et le bon fonctionnement des processus et des produits sont parmi les préoccupations majeures dans l’industrie sidérurgique. Au niveau de l’unité de préparation de la matière et agglomération (PMA) du complexe sidérurgique IMETAL El-Hadjar - Annaba, l’évaluation des performances des ventilateurs de dépoussiérage est une tâche extrêmement importante pour assurer leur sûreté et leur fiabilité. Il est donc indispensable de mettre en œuvre des méthodes fiables de contrôle et de surveillance afin de détecter de façon précise l’apparition de signe de défaillance. Dans ce travail, nous proposons l’utilisation de la carte auto-organisée (SOM) (en anglais. Self-Organizing Map) pour évaluer le ventilateur de dépoussiérage sur la base de calcul des indices de détection performants. Chaque indice est évalué par l’analyse de son changement et de sa variation par rapport à l’état sain. Les différents résultats obtenus montrent que l’approche proposée donne une évaluation globale et améliore considérablement la performance des indices calculés utilisés pour l’évaluation du ventilateur. Voir les détails
Mots clés : Carte auto-organisée (SOM), Indice de détection, surveillance, Industrie sidérurgique, Ventilateur de dépoussiérage
Image compression of Surface defects of the hot-rolled steelstrip using discrete Cosine Transform and Discrete Wavelet Transform
Automatic quality control of surface of hot rolled steel using computer vision systems is a real timeapplication, which requires highly efficient Image compression techniques in order to improve the data transmissionand storage capacity.In this work, two image compression methods are simulated. They are Discrete Cosine Transform(DCT) and Discrete Wavelet Transform (DWT).The results of simulation are shown that The Discrete WaveletTransform (DWT) technique given improved result compared with Discrete Cosine Transform (DCT). Voir les détails
Mots clés : Automatic quality control, Computer vision, image compression, Cosine transform, wavelets transform
Image compression of Surface defects of the hot-rolled steelstrip using discrete Cosine Transform and Discrete WaveletTransform
Automatic quality control of surface of hot rolled steel using computer vision systems is a real timeapplication, which requires highly efficient Image compression techniques in order to improve the data transmissionand storage capacity.In this work, two image compression methods are simulated. They are Discrete Cosine Transform(DCT) and Discrete Wavelet Transform (DWT).The results of simulation are shown that The Discrete WaveletTransform (DWT) technique given improved result compared with Discrete Cosine Transform (DCT). Voir les détails
Mots clés : Automatic quality control, Computer vision, image compression, Cosine transform, wavelets transform.
Approche expérimentale des causes d’endommagement des marteaux de concassage
Les matériaux résistant à l’usure sont fortement demandés par divers secteurs industriels (industries minières, métallurgiques et autres). Ils constituent des pièces maîtresses des concasseurs et des broyeurs utilisés pour la préparation des matières. Plusieurs nuances d’aciers sont produites pour répondre aux besoins de divers secteurs industriels. D’autres aciers martensitiques à haute teneur en carbone et en chrome sont aussi produits pour répondre à des sollicitations nécessitant une résistance à l’usure élevée.Dans ce travail nous nous intéressons aux causes de dégradation prématurée des marteaux de concassage. Ces marteaux, à leur entrée en service, cassent au niveau de la bride de fixation en libérant la majeure partie de la pièce dans le concasseur. Le matériau étudié est un acier à haute teneur en chrome. Plusieurs techniques ont été employées pour caractériser ce matériau et détecter les causes qui sont à l’origine de ce problème. Les échantillons ont été analysés par spectrométrie X. La microscopie a contribué à la révélation de la microstructure et aussi à faire ressortir les éventuels défauts micro et macroscopiques existants. La diffraction des rayons X a aidé à détecter le type et la proportion des phases microstructurales. Voir les détails
Mots clés : Acier moulé, endommagement, marteau de concassage, usure, microstructure, défauts
Effect of heat treatment temperature on thestructural evolution of hot forged steel balls used forgrinding raw material in cement industry
The raw material preparation sector such as cementworks, the steel and mining sector is beginning to pay attention toforged balls as an alternative to the cast balls for their best usecharacteristics. The forging materials are stronger than thecasting material because of their fiber structure. The forgingtechnique, in contrast to the casting process, contributes to asignificant improvement of ball wear behavior during thegrinding process.The wear behavior depends on several factors including thechemical composition of the alloy, the type of microstructure andthe applied heat treatment. In this work we focus on the effect ofaustenitizing temperature on the type of the producedmicrostructure. Al the heat treatment parameters were fixed forall the samples except the austenitizing temperature. Threeaustenitizing temperatures are selected and a tempering at 250°C with a holding time of one hour followed by cooling has beencarried out. The study is carried out on medium micro-alloyedcarbon steel intended for heat treatment.To make clear the effect of the temperature on themicrostructural transformation, several investigations wereachieved. Optical and SEM microscopy was carried out toqualitatively characterize the phases A microstructural analysisusing the Rietveld method was conducted to access, for eachtemperature, the type and proportion of phases as well as thecrystallites size. Voir les détails
Mots clés : grinding balls, forging, heat treatment, characterization, XRD analysis, Rietveld refinement
EFFECT OF HEAT TREATMENT ON WEAR BEHAVIOUR OF FORGEDSTEEL BALLS
The raw material preparation sector such as cementworks, the steel and mining sector is beginning to pay attention toforged balls as an alternative to the cast balls for their best usecharacteristics. The forging materials are stronger than thecasting material because of their fiber structure. The forgingtechnique, in contrast to the casting process, contributes to asignificant improvement of ball wear behavior during thegrinding process.The wear behavior depends on several factors including thechemical composition of the alloy, the type of microstructure andthe applied heat treatment. In this work we focus on the effect ofaustenitizing temperature on the type of the producedmicrostructure. Al the heat treatment parameters were fixed forall the samples except the austenitizing temperature. Threeaustenitizing temperatures are selected and a tempering at 250°C with a holding time of one hour followed by cooling has beencarried out. The study is carried out on medium micro-alloyedcarbon steel intended for heat treatment.To make clear the effect of the temperature on themicrostructural transformation, several investigations wereachieved. Optical and SEM microscopy was carried out toqualitatively characterize the phases A microstructural analysisusing the Rietveld method was conducted to access, for eachtemperature, the type and proportion of phases as well as thecrystallites size. Voir les détails
Mots clés : grinding balls, forging, heat treatment, characterization, XRD analysis, Rietveld refinement
Characterization and valorization of steel co-products
The iron industries generate large quantities of slags and mill scale at different scales. We have focused on the physicochemical characterization of slag and battitures from the El Hadjar sideal complex. To evaluate the quality of these co-products, we first used particle size analysis by the laser method followed by density measurements. Finally a microstructural analysis by X-ray diffraction has been completed. Voir les détails
Mots clés : slag, Battitures, valorization, characterization
Improvement the surface hardness of XC38 steel by heat treatment - Approach by factorial plans
The surface hardness plays an important role in the service life of a mechanicals parts subjected to friction and wear. It can be improved by mechanical treatments or heat treatments. The latter occupy an important place in steel metallurgy, they aim to improve the performance of mechanicals properties of materials such as resilience and hardness and consequently they contribute in a visible way to the good resistance to fatigue and wear treated pieces. This work aims to predict the surface hardness Hv as a function of heat treatment parameters in this case the treatment temperature and holding time. therefore thermals treatments have been envisaged following the methodology of factorial plans 22 where two parameters have been considered, the temperature "T" and the holding time "t" where each parameter at two levels (min, max). These treatments were applied on forged XC38 steel samples, the obtained results have resulted in a mathematical model evaluating the surface hardness "Hv" as a function of treatment temperature and holding time. The experimental results indicate for this steel that holding time minimum and temperature minimum (t = 2h, T = 850 ° c) have an apparent significant effect where "Hv" achieved the value of 750 (Hvi = 179). Voir les détails
Mots clés : heat treatment, superficial hardness, factorial designs, Mathematical model
RISK OF CONTAMINATION OF ANNABA CITY LITTORAL BY THE MILL SCALE
A significant amount of scale is produced during casting of ingots and processing of hot-rolled products. In the El Hadjar steel complex, during the various rolling operations, the amount of scale produced is approximately 0.1% of the annual production of the rolling mills. The quality of the thin sheet during rolling is affected by the behavior of the iron oxide layers formed on their surfaces. For this reason,acids and oils are used for the descaling of slabs and billets by means of pressurized water. The calamine, contaminated by these various acids and used oils, is rejected and stored involuntarily on important areas and pollutes soil and groundwater. Micrographic observations as well as X-ray diffraction analysis have shown that calamine consists mainly of iron oxides. Hematite and magnetite become the main components for oxidation times greater than 1 hour. Characterization tests have shown that calamine is dense (ρ = 4.8 g cm3), its particle size is variable depending on the degree of oxidation (from 0.5 to 10 mm). Simultaneous thermal analysis showed that an increase in mass of the calamine sample with a release of heat. Studies are underway for the physico-chemical characterization of the soils of the storage areas. Voir les détails
Mots clés : Scale, Risks, soil, thermal analysis, granulometry, X-ray diffraction
SIMULATION DE L’INTENSITE DU FLUX SOLAIRE CONCENTRE RECUS AU NIVEAU DE L’ABSORBEUR
La plus grande ressource d’énergie techniquement accessible sur la planète est disponible dans les régions désertiques. Nous allons étudier plus particulièrement l’énergie solaire qui permet de récupérer la chaleur du rayonnement solaire au sein d’un fluide, cela par la conversion de l’énergie noble (énergie solaire) en énergie thermique par la mise en œuvre des capteurs solaires thermiques. Le présent travail propose une étude numérique des performances optiques d’un concentrateur cylindro-parabolique à eau, nous avons simulé la distribution du flux solaire autour du tube absorbeur à l’aide d’un logiciel SOLRACE en utilisant la méthode de Monté Carlo Ray-tracing. Voir les détails
Mots clés : Concentrateur cylindro-parabolique, Flux solaire, Simulation.