WO2004078368A1 - Method from the separation of forged and cast metal alloys - Google Patents

Method from the separation of forged and cast metal alloys Download PDF

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Publication number
WO2004078368A1
WO2004078368A1 PCT/FR2004/000221 FR2004000221W WO2004078368A1 WO 2004078368 A1 WO2004078368 A1 WO 2004078368A1 FR 2004000221 W FR2004000221 W FR 2004000221W WO 2004078368 A1 WO2004078368 A1 WO 2004078368A1
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Prior art keywords
image
sorting
parts
alloys
forged
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PCT/FR2004/000221
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French (fr)
Inventor
Serge Terroni
Joseph Pierquin
Bruno Dubost
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Aluminium Pechiney
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Publication of WO2004078368A1 publication Critical patent/WO2004078368A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
    • B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
    • B07C5/34—Sorting according to other particular properties
    • B07C5/342—Sorting according to other particular properties according to optical properties, e.g. colour
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/55—Specular reflectivity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
    • G01N21/718—Laser microanalysis, i.e. with formation of sample plasma
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
    • B07C2501/00—Sorting according to a characteristic or feature of the articles or material to be sorted
    • B07C2501/0036—Sorting out metallic particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
    • B07C2501/00—Sorting according to a characteristic or feature of the articles or material to be sorted
    • B07C2501/0054—Sorting of waste or refuse

Definitions

  • the invention relates to the automatic separation of parts from wrought metal alloys, that is to say parts made from semi-rolled products, spun or forged, and molded parts, and more particularly waste such parts, such as waste aluminum alloy parts from the recycling of used motor vehicles.
  • waste aluminum alloys have been practiced for many years because of their high intrinsic value and the relative ease of recycling.
  • a major source of waste is end-of-life motor vehicles, which are compacted and crushed.
  • most of the aluminum alloys used in the automobile came from castings, including engine parts (engine blocks, cylinder heads, pistons, etc.). These parts are mostly aluminum alloys with a high silicon content.
  • the use of wrought aluminum alloy parts has developed strongly, for example alloy body panels of the 6000 series (Al-Si-Mg) or the 5000 series (Al-Mg alloys). , profiles for bumpers and structures, and thin strips for heat exchangers of engine cooling and air conditioning systems.
  • the main sorting techniques mentioned in the article are: - color sorting, which makes it possible to distinguish the different categories of alloys by virtue of the color obtained by a suitable surface chemical treatment, as described in patent EP 0861910 (Alcoa) .
  • the sorting can then be carried out using a camera placed above the conveyor belt of the waste to be sorted, as indicated in the patent application WO 95/17974 (Huron Valley Steel Corp.).
  • the use of certain chemicals can cause problems with effluent disposal.
  • laser ablation spectrometry or "laser induced breakdown spectroscopy” or LIBS.
  • This technique is described in particular in patent EP 0293983 (Metalgesellschaft). This method is particularly sensitive to the surface condition.
  • the object of the present invention is to provide a sorting method between the cast metal alloy parts and those from rolled or spun semi-finished products, which is reliable, simple and economical.
  • the invention relates to a method for separating parts made of metal alloys, especially aluminum alloys, molded or obtained from rolled, spun or forged products, consisting in producing an image of the surface of the parts by a method allowing to differentiate the surfaces having a periodic roughness profile and / or preferred direction of random roughness profile surfaces, and to sort the pieces according to the image obtained. It relates in particular to a method of this type in which the method for differentiating surfaces consists of producing on a screen, using a laser beam, a reflected image of the surface of the part, and to record this image. It also relates to a method for sorting metal parts comprising a first sorting by the above method, and a second sorting by another method of the prior art such as colorimetric sorting or laser ablation spectrometry.
  • Figure 1 is an experimental circuit diagram illustrating the principle of laser reflectometry.
  • Figures 2a, 2b, 2c and 2d respectively show the type of laser reflection image obtained from a perfectly polished surface, an isotropic rough surface and an anisotropic rough surface with or without surface diffusion.
  • Figures 3a and 3b are photographs obtained by laser reflection respectively for a molded part and a rolled part.
  • Figures 4a and 4b show in perspective, respectively from above and below, a block diagram of a sorting installation using the method according to the invention.
  • the invention is based on the finding that the surface roughness of the molded parts and the pieces from wrought half-products have different profiles.
  • the roughness profile of the molded parts is isotropic, with random height fluctuations, while that of the rolled or extruded products has a preferred direction and / or a certain periodicity. If, by a given method, a different image of the surface of the parts is produced, depending on whether the roughness profile is isotropic or anisotropic, and the parts are separated according to this image, a means is available. to separate on the one hand castings and on the other hand the parts from rolled products, forged or spun. This principle of separation applies to all metals and alloys that can be transformed by rolling, forging, spinning or molding, since these transformation techniques generate the same type of surface roughness whatever the metal.
  • a particularly suitable method for obtaining an image representative of the type of roughness of the surface is laser reflectometry.
  • the principle of the method is illustrated by the experimental setup of FIG. 1.
  • the beam is directed on the sample to identify the beam of a laser of adapted power.
  • the reflected image is recovered on a screen and photographed.
  • the image obtained is a point, as shown in Figure 2a.
  • each element of this surface will behave as a light source emitting a spherical wave.
  • the phase difference between these waves is at the origin of interference which, depending on the case, will lead to either a bright spot or a dark spot. This produces a granular image, often called "speckle" characterized by a multitude of bright spots on a dark background.
  • the surface roughness is isotropic, i.e.
  • the surface roughness is anisotropic, that is to say it has a preferred direction and / or repetitive patterns with a fairly regular pitch, as is the case for rolled, forged or spun metal products
  • the reflected beam is discretized, the light energy being concentrated along particular directions called diffraction orders.
  • the reflected image associates with the specular reflection a diffraction line called "comet", as illustrated in Figure 2c.
  • the images obtained are sufficiently differentiated to be able to use relatively simple image analysis techniques for the sorting itself, for example a form recognition for identification of the comet, a measurement of luminous flux or a measurement of maximum intensity for evaluation of specular reflectance.
  • the process according to the invention is applicable to the separation of castings on the one hand and forged parts or pieces of rolled products (sheets) or extruded products (profiles, bars and tubes) from a large number of metals and alloys, since the discrimination is made not by the chemical composition, but by the surface condition resulting from its mode of transformation. Although it does not apply to coated products, such as painted or lacquered products, this restriction is hardly restrictive for waste resulting from grinding.
  • the grinding removes, at least partially, the paint layer, and the sample can then be recognized. It is the same for dirty or greasy parts.
  • the laser scanning, or passing samples in front of a fixed laser beam is a continuous operation, so that the probability that the beam will not encounter a surface area having the typical roughness of the transformation mode is very small. This makes the process more reliable than point methods like spectrometry from a laser shot. This results in very low pollution of the pool of recovered wrought waste.
  • the method according to the invention has a low implementation cost, thanks to the use of low power lasers, and means of acquisition and processing of unsophisticated images. If it is desired to further sort, for example by alloy type, the method according to the invention can be followed by other sorting methods of the prior art, such as colorimetric sorting or laser ablation spectrometry. .
  • FIG. 3a is the photograph obtained for a sample of alloy casting A-S7G (alloy with 7% silicon), and FIG. 3b for a sample of laminated part in alloy 5182. We find indeed a comet shape in the first case, and halo in the second case, sufficiently differentiated to allow sorting between the two types of alloys.
  • Figures 4a and 4b show a block diagram of an experimental sorting device for carrying out the method according to the invention. It has a laser source

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
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  • Analytical Chemistry (AREA)
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  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
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Abstract

The invention relates to a method for the separation of pieces of metal alloys, particularly aluminium alloys which are cast or obtained from laminated, rolled or forged products which comprises producing an image of the surface of the pieces, using a method which permits the differentiation of the surfaces with a periodic roughness profile and/or with a favoured direction for the surfaces with a random roughness profile and to sort the pieces as a function of the obtained image. The method for the differentiation of the surfaces is preferably laser reflectometry.

Description

Procédé de séparation d'alliages métalliques corroyés et moulés. Process for separating wrought and cast metal alloys
Domaine de l'inventionField of the invention
L'invention concerne la séparation automatique des pièces en alliages métalliques corroyées, c'est-à-dire de pièces fabriquées à partir de demi-produits laminés, filés ou forgés, et de pièces moulées, et plus particulièrement de déchets de telles pièces, comme par exemple les déchets de pièces en alliages d'aluminium provenant du recyclage des véhicules automobiles hors d'usage.The invention relates to the automatic separation of parts from wrought metal alloys, that is to say parts made from semi-rolled products, spun or forged, and molded parts, and more particularly waste such parts, such as waste aluminum alloy parts from the recycling of used motor vehicles.
Etat de la techniqueState of the art
Le recyclage des déchets en alliages d'aluminium est pratiqué depuis de nombreuses années en raison de leur valeur intrinsèque assez élevée et de la facilité relative de ce recyclage. Une source importante de déchets provient des véhicules automobiles en fin de vie, qui sont compactés et broyés. Jusqu'à une date récente, la majeure partie des alliages d'aluminium utilisés dans l'automobile provenait de pièces moulées, notamment des pièces de moteurs (blocs-moteur, culasses, pistons, etc.). Ces pièces sont pour la plupart en alliages d'aluminium à forte teneur en silicium. Depuis quelques années, l'utilisation de pièces en alliages d'aluminium corroyés s'est fortement développée, par exemple des tôles de carrosserie en alliages de la série 6000 (Al-Si-Mg) ou de la série 5000 (alliages Al-Mg, des profilés pour pare-chocs et structures, et des bandes minces pour les échangeurs de chaleur des systèmes de refroidissement du moteur et de climatisation.The recycling of waste aluminum alloys has been practiced for many years because of their high intrinsic value and the relative ease of recycling. A major source of waste is end-of-life motor vehicles, which are compacted and crushed. Until recently, most of the aluminum alloys used in the automobile came from castings, including engine parts (engine blocks, cylinder heads, pistons, etc.). These parts are mostly aluminum alloys with a high silicon content. In recent years, the use of wrought aluminum alloy parts has developed strongly, for example alloy body panels of the 6000 series (Al-Si-Mg) or the 5000 series (Al-Mg alloys). , profiles for bumpers and structures, and thin strips for heat exchangers of engine cooling and air conditioning systems.
La valeur des déchets est d'autant plus importante qu'ils sont plus homogènes quant à leur composition chimique. Pour cette raison, des techniques de séparation ont été développées récemment. L'article « Scrap Séparation Advances to boost Secondary Business », paru dans Aluininium Today de juillet-août 2001 (pages 22-23) décrit la problématique technique et économique du recyclage des déchets d'alliages d'aluminium. L'augmentation de l'utilisation d'alliages corroyés dans l'automobile risque de conduire à un surplus d'aluminium de deuxième fusion par rapport aux besoins des alliages de moulage, et, pour que les déchets de pièces moulées aillent en priorité aux alliages de moulage de deuxième fusion, il est intéressant de faire un premier tri entre les déchets de pièces moulées et celles issues de demi-produits filés, forgés ou laminés. Les principales techniques de tri mentionnées dans l'article sont : - le tri colorimétrique, qui permet de distinguer les différentes catégories d'alliages grâce à la couleur obtenue par un traitement chimique de surface approprié, comme décrit dans le brevet EP 0861910 (Alcoa). Le tri peut alors être effectué à l'aide d'une caméra placée au-dessus de la bande transporteuse des déchets à trier, comme indiqué dans la demande de brevet WO 95/17974 (Huron Valley Steel Corp.). L'utilisation de certains produits chimiques peut poser des problèmes d'évacuation des effluents.The value of the waste is all the more important as they are more homogeneous in terms of their chemical composition. For this reason, separation techniques have been developed recently. The article "Scrap Separation Advances to boost Secondary Business", published in Aluininium Today from July-August 2001 (pages 22-23) describes the technical and economic problem of recycling waste aluminum alloys. The increase in the use of wrought alloys in the automobile may lead to a surplus of secondary aluminum over the need for casting alloys, and, in order for the molded parts waste to go primarily to secondary-casting alloys, it is interesting to make a first sorting between the scrap of castings and those from semi-finished products, forged or rolled. The main sorting techniques mentioned in the article are: - color sorting, which makes it possible to distinguish the different categories of alloys by virtue of the color obtained by a suitable surface chemical treatment, as described in patent EP 0861910 (Alcoa) . The sorting can then be carried out using a camera placed above the conveyor belt of the waste to be sorted, as indicated in the patent application WO 95/17974 (Huron Valley Steel Corp.). The use of certain chemicals can cause problems with effluent disposal.
- la spectrométrie par ablation laser, en anglais « laser induced breakdown spectroscopy » ou LIBS. Cette technique est décrite notamment dans le brevet EP 0293983 (Metalgesellschaft). Cette méthode est particulièrement sensible à l'état de surface.laser ablation spectrometry, or "laser induced breakdown spectroscopy" or LIBS. This technique is described in particular in patent EP 0293983 (Metalgesellschaft). This method is particularly sensitive to the surface condition.
D'autres méthodes de tri ont également été proposées, par exemple dans l'article de A. Gesing et al. « Séparation of Wrought Fraction of Aluminum Recovered from Automobile Shredder Scrap » TMS Annual Meeting & Exhibition, 12/02/2001, comme les rayons X ou les courants de Foucault multifréquence, cette dernière technique étant assez sensible à la forme des objets à reconnaître.Other sorting methods have also been proposed, for example in the article by A. Gesing et al. This technique is quite sensitive to the shape of the objects to be recognized, such as x-rays or eddy-current multifrequency. TMS Annual Meeting & Exhibition, 12/02/2001.
Le but de la présente invention est de fournir une méthode de tri entre les pièces en alliages métalliques moulées et celles provenant de demi-produits laminés ou filés, qui soit fiable, simple et économique.The object of the present invention is to provide a sorting method between the cast metal alloy parts and those from rolled or spun semi-finished products, which is reliable, simple and economical.
Objet de l'inventionObject of the invention
L'invention a pour objet un procédé de séparation de pièces en alliages métalliques, notamment en alliages d'aluminium, moulées ou obtenues à partir de produits laminés, filés ou forgés, consistant à produire une image de la surface des pièces par une méthode permettant de différencier les surfaces présentant un profil de rugosité périodique et/ou à direction privilégiée des surfaces à profil de rugosité aléatoire, et à trier les pièces en fonction de l'image obtenue. Elle a en particulier pour objet un procédé de ce type dans lequel la méthode permettant de différencier les surfaces consiste à produire sur un écran, à l'aide d'un faisceau laser, une image réfléchie de la surface de la pièce, et à enregistrer cette image. Elle a également pour objet un procédé de tri de pièces métalliques comportant un premier tri par le procédé précédent, et un second tri par un autre procédé de l'art antérieur tel que le tri colorimétrique ou la spectrométrie par ablation laser.The invention relates to a method for separating parts made of metal alloys, especially aluminum alloys, molded or obtained from rolled, spun or forged products, consisting in producing an image of the surface of the parts by a method allowing to differentiate the surfaces having a periodic roughness profile and / or preferred direction of random roughness profile surfaces, and to sort the pieces according to the image obtained. It relates in particular to a method of this type in which the method for differentiating surfaces consists of producing on a screen, using a laser beam, a reflected image of the surface of the part, and to record this image. It also relates to a method for sorting metal parts comprising a first sorting by the above method, and a second sorting by another method of the prior art such as colorimetric sorting or laser ablation spectrometry.
Description des figuresDescription of figures
La figure 1 est un schéma de montage expérimental illustrant le principe de la réflectométrie laser.Figure 1 is an experimental circuit diagram illustrating the principle of laser reflectometry.
Les figures 2a, 2b, 2c et 2d représentent respectivement le type d'image en réflexion laser obtenues à partir d'une surface parfaitement polie, d'une surface rugueuse isotrope et d'une surface rugueuse anisotrope sans ou avec diffusion de surface.Figures 2a, 2b, 2c and 2d respectively show the type of laser reflection image obtained from a perfectly polished surface, an isotropic rough surface and an anisotropic rough surface with or without surface diffusion.
Les figures 3 a et 3b sont des photographies obtenues par réflexion laser respectivement pour une pièce moulée et une pièce laminée.Figures 3a and 3b are photographs obtained by laser reflection respectively for a molded part and a rolled part.
Les figures 4a et 4b représentent en perspective, respectivement à partir du dessus et du dessous, un schéma de principe d'une installation de tri utilisant le procédé selon l'invention.Figures 4a and 4b show in perspective, respectively from above and below, a block diagram of a sorting installation using the method according to the invention.
Description de l'inventionDescription of the invention
L'invention est basée sur la constatation que les rugosités de surface des pièces moulées et des pièces issues de demi-produits corroyés présentent des profils différents. Le profil de rugosité des pièces moulées est isotrope, avec des fluctuations de hauteur aléatoires, tandis que celui des pièces issues de produits laminés ou filés présente une direction privilégiée et/ou une certaine périodicité. Si on produit, par une méthode déterminée, une image de la surface des pièces qui soit différente selon que le profil de rugosité est isotrope ou anisotrope, et qu'on sépare les pièces en fonction de cette image, on dispose ainsi d'un moyen de séparer d'une part les pièces moulées et d'autre part les pièces issues de produits laminés, forgés ou filés. Ce principe de séparation s'applique à tous les métaux et alliages qu'on peut transformer par laminage, forgeage, filage ou moulage, puisque ces techniques de transformation génèrent le même type de rugosité superficielle quel que soit le métal.The invention is based on the finding that the surface roughness of the molded parts and the pieces from wrought half-products have different profiles. The roughness profile of the molded parts is isotropic, with random height fluctuations, while that of the rolled or extruded products has a preferred direction and / or a certain periodicity. If, by a given method, a different image of the surface of the parts is produced, depending on whether the roughness profile is isotropic or anisotropic, and the parts are separated according to this image, a means is available. to separate on the one hand castings and on the other hand the parts from rolled products, forged or spun. This principle of separation applies to all metals and alloys that can be transformed by rolling, forging, spinning or molding, since these transformation techniques generate the same type of surface roughness whatever the metal.
Une méthode particulièrement appropriée pour obtenir une image représentative du type de rugosité de la surface est la réflectométrie laser. Le principe de la méthode est illustré par le montage expérimental de la figure 1. On dirige sur l'échantillon à identifier le faisceau d'un laser de puissance adaptée. L'image réfléchie est récupérée sur un écran et photographiée.A particularly suitable method for obtaining an image representative of the type of roughness of the surface is laser reflectometry. The principle of the method is illustrated by the experimental setup of FIG. 1. The beam is directed on the sample to identify the beam of a laser of adapted power. The reflected image is recovered on a screen and photographed.
Une surface métallique parfaitement polie, et donc non rugueuse, réfléchit les rayonnements de manière spéculaire, c'est-à-dire qu'on a une réflexion totale selon une direction symétrique par rapport à la normale de celle du rayon incident. Dans le cas d'un miroir parfait, l'image obtenue est un point, comme indiqué à la figure 2a. Si, au contraire, la surface de l'échantillon présente une certaine rugosité, chaque élément de cette surface va se comporter comme une source de lumière émettant une onde sphérique. Le déphasage entre ces ondes est à l'origine d'interférences qui, selon les cas, vont conduire soit à une tache lumineuse, soit à une tache sombre. On obtient ainsi une image granuleuse, souvent appelée « speckle » caractérisée par une multitude de taches brillantes sur un fond sombre. Si la rugosité de surface est isotrope, c'est-à-dire présente des fluctuations de hauteur aléatoires, comme c'est le cas pour les produits métalliques moulés, on obtient une image réfléchie avec un halo de diffusion et une faible réflexion spéculaire, comme indiqué à la figure 2b. Si la rugosité de surface est anisotrope, c'est-à-dire présente une direction privilégiée et/ou des motifs répétitifs avec un pas à peu près régulier, comme c'est le cas pour les produits métalliques laminés, forgés ou filés, le faisceau réfléchi est discrétisé, l'énergie lumineuse étant concentrée selon des directions particulières appelées ordres de diffraction. Dans ce cas, l'image réfléchie associe à la réflexion spéculaire un trait de diffraction appelé « comète », comme illustré à la figure 2c. Les images obtenues sont suffisamment différenciées pour pouvoir utiliser pour le tri proprement dit des techniques d'analyse d'image relativement simples, par exemple une reconnaissance de forme pour identification de la comète, une mesure de flux lumineux ou une mesure d'intensité maximale pour évaluation de la réflectance spéculaire. Le procédé selon l'invention s'applique à la séparation de pièces moulées d'une part et de pièces forgées ou issues de produits laminés (tôles) ou filés (profilés, barres et tubes) d'un grand nombre de métaux et alliages, puisque la discrimination se fait non pas par la composition chimique, mais par l'état de surface résultant de son mode de transformation. Bien qu'il ne s'applique pas aux produits revêtus, comme les produits peints ou laqués, cette restriction n'est guère limitative pour les déchets résultant du broyage. En effet, le broyage enlève, au moins partiellement, la couche de peinture, et l'échantillon peut alors être reconnu. Il en est de même pour les pièces sales ou grasses. Le balayage laser, ou le passage des échantillons devant un faisceau laser fixe, est une opération continue, de sorte que la probabilité pour que le faisceau ne rencontre pas une zone de surface présentant la rugosité typique du mode de transformation est très faible. Ceci rend le procédé plus fiable que les méthodes ponctuelles comme la spectrométrie à partir d'un tir laser. Il en résulte une très faible pollution du gisement de déchets corroyés récupérés. Le procédé selon l'invention a un coût de mise en oeuvre faible, grâce à l'utilisation de lasers de faible puissance, et de moyens d'acquisition et de traitement d'images peu sophistiqués. Si l'on souhaite un tri plus poussé, par exemple par type d'alliage, on peut faire suivre le procédé selon l'invention d'autres procédés de tri de l'art antérieur, comme le tri colorimétrique ou la spectrométrie par ablation laser.A perfectly polished metal surface, and therefore non-rough, reflects the radiation specularly, that is to say we have a total reflection in a direction symmetrical with respect to the normal of the incident ray. In the case of a perfect mirror, the image obtained is a point, as shown in Figure 2a. If, on the contrary, the surface of the sample has a certain roughness, each element of this surface will behave as a light source emitting a spherical wave. The phase difference between these waves is at the origin of interference which, depending on the case, will lead to either a bright spot or a dark spot. This produces a granular image, often called "speckle" characterized by a multitude of bright spots on a dark background. If the surface roughness is isotropic, i.e. exhibits random height fluctuations, as is the case with cast metal products, a reflected image with a diffusion halo and low specular reflection is obtained. as shown in Figure 2b. If the surface roughness is anisotropic, that is to say it has a preferred direction and / or repetitive patterns with a fairly regular pitch, as is the case for rolled, forged or spun metal products, the The reflected beam is discretized, the light energy being concentrated along particular directions called diffraction orders. In this case, the reflected image associates with the specular reflection a diffraction line called "comet", as illustrated in Figure 2c. The images obtained are sufficiently differentiated to be able to use relatively simple image analysis techniques for the sorting itself, for example a form recognition for identification of the comet, a measurement of luminous flux or a measurement of maximum intensity for evaluation of specular reflectance. The process according to the invention is applicable to the separation of castings on the one hand and forged parts or pieces of rolled products (sheets) or extruded products (profiles, bars and tubes) from a large number of metals and alloys, since the discrimination is made not by the chemical composition, but by the surface condition resulting from its mode of transformation. Although it does not apply to coated products, such as painted or lacquered products, this restriction is hardly restrictive for waste resulting from grinding. Indeed, the grinding removes, at least partially, the paint layer, and the sample can then be recognized. It is the same for dirty or greasy parts. The laser scanning, or passing samples in front of a fixed laser beam, is a continuous operation, so that the probability that the beam will not encounter a surface area having the typical roughness of the transformation mode is very small. This makes the process more reliable than point methods like spectrometry from a laser shot. This results in very low pollution of the pool of recovered wrought waste. The method according to the invention has a low implementation cost, thanks to the use of low power lasers, and means of acquisition and processing of unsophisticated images. If it is desired to further sort, for example by alloy type, the method according to the invention can be followed by other sorting methods of the prior art, such as colorimetric sorting or laser ablation spectrometry. .
ExempleExample
On a soumis un certain nombre de déchets d'alliages d'aluminium, provenant du broyage de véhicules hors d'usage, et séparés par flottation, au dispositif expérimental décrit à la figure 1. On a utilisé comme source un laser de faible puissance (10 mW) de type hélium-néon, de longueur d'onde 632 nm, dont le faisceau est dirigé vers les déchets. L'image réfléchie sur écran est photographiée à l'aide d'un appareil Polaroid E600 muni d'un objectif de 127 mm. La distance entre l'objectif et l'écran était de 1,60 m et le temps de pose de Vi s. La figure 3a est la photographie obtenue pour un échantillon de pièce moulée en alliage A-S7G (alliage à 7% de silicium), et la figure 3b pour un échantillon de pièce laminée en alliage 5182. On retrouve bien une forme de comète dans le premier cas, et de halo dans le second cas, suffisamment différenciées pour permettre un tri entre les deux types d'alliages.A number of aluminum alloy scrap from the crushing of scrap vehicles, separated by flotation, was subjected to the experimental device described in Figure 1. A low power laser was used as the source ( 10 mW) helium-neon type, wavelength 632 nm, whose beam is directed to the waste. The image reflected on the screen is photographed using a Polaroid E600 camera with a lens of 127 mm. The distance between the lens and the screen was 1.60 m and the exposure time of Vi s. FIG. 3a is the photograph obtained for a sample of alloy casting A-S7G (alloy with 7% silicon), and FIG. 3b for a sample of laminated part in alloy 5182. We find indeed a comet shape in the first case, and halo in the second case, sufficiently differentiated to allow sorting between the two types of alloys.
Si on diminue le temps de pose à 1/8 s, on obtient toujours une comète pour la pièce laminée, mais, pour la pièce moulée, le flux lumineux réfléchi est insuffisant pour imprimer un film photographique de sensibilité 300 AS A. On peut donc utiliser une simple mesure de flux lumineux pour faire le tri.If we reduce the exposure time to 1/8 s, we still get a comet for the rolled part, but, for the molded part, the reflected light flux is insufficient to print a photographic film of sensitivity 300 AS A. We can therefore use a simple light flow measurement to sort.
Les figures 4a et 4b montrent un schéma de principe d'un dispositif expérimental de tri pour la mise en oeuvre du procédé selon l'invention. Il comporte une source laserFigures 4a and 4b show a block diagram of an experimental sorting device for carrying out the method according to the invention. It has a laser source
(1) réglable en hauteur et en rotation, deux platines (2) et (3) pour recevoir les échantillons, qui simulent le convoyeur d'une installation industrielle, deux plaques en verre dépoli (4) surmontées d'un capot en forme de pyramide tronquée, au sommet duquel se trouve une caméra (5) de position réglable en longueur et en hauteur. En fonction de la position et de la forme de l'échantillon, le faisceau laser se réfléchit sur l'une ou l'autre des plaques (4). L'image réfléchie peut alors être saisie et traitée par la caméra (5). (1) adjustable in height and rotation, two plates (2) and (3) to receive the samples, which simulate the conveyor of an industrial installation, two frosted glass plates (4) surmounted by a hood in the form of truncated pyramid, at the top of which is a camera (5) of position adjustable in length and height. Depending on the position and shape of the sample, the laser beam is reflected on one or other of the plates (4). The reflected image can then be captured and processed by the camera (5).

Claims

Revendicationsclaims
l. Procédé de séparation de pièces en alliages métalliques moulées ou obtenues à partir de produits laminés, forgés ou filés, consistant à produire une image de la surface des pièces par une méthode permettant de différencier les surfaces présentant un profil de rugosité périodique et/ou à direction privilégiée des surfaces à profil de rugosité aléatoire, et à trier les pièces en fonction de l'image obtenue.l. Process for separating cast metal alloys or parts obtained from rolled, forged or spun products, consisting in producing an image of the surface of the parts by a method making it possible to differentiate the surfaces having a periodic and / or directional roughness profile preferred surfaces with a random roughness profile, and to sort the pieces according to the image obtained.
2. Procédé selon la revendication 1, caractérisé en ce que les alliages métalliques sont des alliages d'aluminium.2. Method according to claim 1, characterized in that the metal alloys are aluminum alloys.
3. Procédé selon l'une des revendications 1 ou 2, caractérisé en ce que la méthode permettant de différencier les surfaces consiste à produire sur un écran, à l'aide d'un faisceau laser, une image réfléchie de la surface de la pièce, et à enregistrer cette image.3. Method according to one of claims 1 or 2, characterized in that the method for differentiating the surfaces is to produce on a screen, using a laser beam, a reflected image of the surface of the room , and to save this image.
4. Procédé de tri de pièces métalliques comportant un premier tri par le procédé selon l'une des revendications 1 à 3, et un second tri par un autre procédé tel que le tri colorimétrique ou la spectrométrie par ablation laser.4. Process for sorting metal parts comprising a first sorting by the method according to one of claims 1 to 3, and a second sorting by another method such as colorimetric sorting or laser ablation spectrometry.
5. Dispositif pour la mise en œuvre du procédé selon l'une des revendications 1 à 3, comportant une source laser (1), au moins une plaque (4) en verre dépoli destinée à recevoir l'image réfléchie, et une caméra (5) pour traiter cette image. 5. Device for implementing the method according to one of claims 1 to 3, comprising a laser source (1), at least one plate (4) of frosted glass for receiving the reflected image, and a camera ( 5) to process this image.
PCT/FR2004/000221 2003-02-04 2004-02-02 Method from the separation of forged and cast metal alloys WO2004078368A1 (en)

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FR03/01239 2003-02-04
FR0301239A FR2850591B1 (en) 2003-02-04 2003-02-04 PROCESS FOR SEPARATING CORROSIUM METAL ALLOYS AND MOLDS

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3305284A1 (en) * 1983-02-16 1984-08-23 Siemens AG, 1000 Berlin und 8000 München Contactless measurement of the gloss of surfaces and coatings
WO1993007468A1 (en) * 1991-10-01 1993-04-15 Oseney Limited Scattered/transmitted light information system
WO2001020308A1 (en) * 1999-09-15 2001-03-22 Rhopoint Instrumentation Limited A glossmeter

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3305284A1 (en) * 1983-02-16 1984-08-23 Siemens AG, 1000 Berlin und 8000 München Contactless measurement of the gloss of surfaces and coatings
WO1993007468A1 (en) * 1991-10-01 1993-04-15 Oseney Limited Scattered/transmitted light information system
WO2001020308A1 (en) * 1999-09-15 2001-03-22 Rhopoint Instrumentation Limited A glossmeter

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FR2850591B1 (en) 2005-03-04

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