EP0042111B1 - Method of and apparatus for the electrostatic powdering of objects in several different layers - Google Patents

Method of and apparatus for the electrostatic powdering of objects in several different layers Download PDF

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Publication number
EP0042111B1
EP0042111B1 EP81104290A EP81104290A EP0042111B1 EP 0042111 B1 EP0042111 B1 EP 0042111B1 EP 81104290 A EP81104290 A EP 81104290A EP 81104290 A EP81104290 A EP 81104290A EP 0042111 B1 EP0042111 B1 EP 0042111B1
Authority
EP
European Patent Office
Prior art keywords
powder
zone
booth
spraying
ionization
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP81104290A
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German (de)
French (fr)
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EP0042111A1 (en
Inventor
Alain Gernez
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Compagnie Europeenne pour lEquipement Menager SA
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Compagnie Europeenne pour lEquipement Menager SA
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Publication of EP0042111A1 publication Critical patent/EP0042111A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
    • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
    • B05D1/06—Applying particulate materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B16/00—Spray booths
    • B05B16/20—Arrangements for spraying in combination with other operations, e.g. drying; Arrangements enabling a combination of spraying operations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B16/00—Spray booths
    • B05B16/90—Spray booths comprising conveying means for moving objects or other work to be sprayed in and out of the booth, e.g. through the booth
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/50—Multilayers
    • B05D7/52—Two layers
    • B05D7/54—No clear coat specified
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/007—Processes for applying liquids or other fluent materials using an electrostatic field
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2451/00—Type of carrier, type of coating (Multilayers)

Definitions

  • the invention relates to a method and a device for electrostatic powdering of objects moving continuously by means of a conveyor through at least two treatment booths, in particular in the booths described in document NL-A-79 08 458.
  • These cabins each include a spray module and two air filtration modules located on either side of the spray module with, between each of these three modules, a compartment allowing the ionization of the powder.
  • the present invention aims to overcome these drawbacks and complications by presenting a method and a device of high reliability and low cost of realization, in particular by avoiding all mechanical equipment which increases the maintenance costs.
  • the subject of the invention is a method of electrostatic powdering of objects moving continuously, by means of a conveyor, through at least two treatment booths, in which in the first booth is deposited a thin layer, called layer of bottom or mass, and in the next cabin a thicker layer, called presentation layer, characterized in that said objects pass successively, in the first cabin, an ionization enclosure, a powder dispersion enclosure without electrostatic charging therefrom, a second ionization enclosure, the powder deposition intervening mainly in the ionization enclosures situated on either side of the dispersion enclosure and not in the dispersion enclosure, then, in the second cabin, an ionization enclosure and an electrostatic spray enclosure, the deposition of powder in the second cabin intervening in these two enclosures.
  • the invention also relates to an electrostatic powdering device for objects moving continuously by means of a conveyor through at least two treatment booths each comprising a powder spraying module framed by air filtration modules. , characterized in that the spray module of the first cabin comprises a non-electrostatic spray chamber disposed between two ionization compartments, and that the spray module of the cabin following the first cabin comprises an electrostatic spray chamber preceded by an ionization compartment.
  • Module A serves as an entry airlock
  • module B is the spray enclosure intended for depositing powder and contains projection elements 22 (FIG. 2)
  • module C is the exit airlock.
  • the module B2 is divided by a partition 48 into two spray compartments B2-1 and B2-2.
  • the module B1 differs from the module B2 only in the absence of this partition.
  • the input-output modules A and C contain vertical cylindrical filters 5, for example four in number per module.
  • a fan 8 allows the suction through the filters and a cleaning unit (not shown) ensures the regeneration of the filters.
  • a fluidization element 3 located at the base of the filters makes it possible to recover the powder which falls from these filters and to return it to a powder reserve 11, 12 situated at the base of the compartments B2-1, B2-2 of the cabin. These contain a fluidization unit 9.
  • the powder deposition elements 22 are of any type, for example spray guns, electrostatic or not.
  • the powder deposition elements 22 are connected to plungers 10 which draw the powder directly from one of the powder reserve tanks 11, 12, a tank for each spraying compartment.
  • the elements 22 are capped with a cover preventing the accumulation of powder thereon.
  • Each spraying module B1, B2 has two ionizing compartments E, F adjacent to the spraying chamber and to the inlet and outlet modules A, C.
  • the powder In the first cabin, the powder is first dispersed in a first enclosure B1 and then electrostatically charged in two contiguous enclosures E and F located upstream and downstream. In the second cabin, powder is pre-applied only by electrostatic forces in compartment E before entering the spraying enclosure B2.
  • An ionizer compartment consists of solid walls 13, 14, 15, 16 leaving a central passage 17 for the parts to be treated. These walls have the effect of constituting obstacles on the path of the powder and thereby further confine the powder in the powdering module B by creating a significant pressure drop during the passage from the powdering chamber B to the chamber. A or C filtration. These obstacles force the powder participating in this transfer to go towards the central axis of the cabin and thereby towards the parts which circulate in the cabin. The fraction of powder still loaded is redeposited on the parts.
  • the ionizing compartments E and F further comprise ionizing elements 21, 23, 25, 27 constituted by insulating tubes arranged vertically in the cabin.
  • These tubes are pierced with holes crossed by spikes 29 so as to leave a space between the spike and the hole.
  • the points are fixed in the wall of the tube opposite the hole according to a generatrix by a fixing means, such as nailing or the like.
  • the tips 29 are directed towards the center of the cabin, perpendicular to the axis of transfer of the parts and pass through a conductive element placed inside the tube and connected to the high voltage.
  • the high voltage source is an electrostatic generator which may be the same as that used for the spray guns in module B; the tips 29 are thus in contact with the conductive element which brings them to a high potential for achieving the ionization of the powder.
  • the conductive element is constituted by a helical spring suspended in the axis of the tube, between the turns from which the tips 29 have passed.
  • the conductive element could be constituted by a metallic braid.
  • the tips are arranged along a generator over the entire height of the tube; one can space, for example, the points of a distance ranging between 10 mm and 100 mm.
  • the insulating tube 21 is closed at one end by an insulating plug through which the high-voltage current supply conductor passes so as to avoid electrostatic leaks: its other end is connected to a supply of compressed air.
  • the tips are brought to a high electrical potential via the conductive element so as to create an ionization of the powder, and the compressed area is sent into the tube.
  • This air, exiting through the holes surrounding the tips, has the effect of preventing powder deposits on the tips, which would harm good ionization of the area and of the powder present in the compartment.
  • a sieve shaker is placed in each ionizer compartment E, F, at the bottom of these compartments, preferably of the type shown in FIGS. 4 and 5; the sieve shaker comprises a wire mesh 34 bonded to a metal frame 35 subjected to vibrations generated by a pneumatic vibrator 37 via a bracket 36.
  • the flexible suspension of the sieve shaker is provided by two rubber bands 38 and 39 which also provide the powder overflow. These bands are fixed on brackets 40, 41, 42 and 43 which can slide longitudinally in two sections 44 and 45 which avoid the retention of powder. This makes it possible to remove the sieves from the cabin for cleaning, by simple lateral extraction by means of two doors drilled in module B.
  • the separation of the metallic particles and the transport of powder to the reservoir tanks 11, 12 constituting the bottom of module B are provided by an inclined sheet 46 subjected to the vibrations of the sieve shaker and provided with parallel strips of magnetic rubber 47 bonded to the sheet. These strips 47 are separated by intervals 48 which allow the accumulation of magnetic particles between two cleanings.
  • the embodiment of the sieve machine according to FIG. 5 ensures a high efficiency of sieving and separation of the metallic particles from the powder.
  • the cabin has two completely independent air filtration compartments A and C. This makes it possible to treat separately and without mixing the powder polluted by any dropouts in the bottom powder (module A2 inlet) and clean powder (module C2 outlet).
  • the cabin having a spraying chamber and a powder reservoir bin separated into two equal or unequal parts B2-1, B2-2, by a wall 48 situated in a plane perpendicular to the axis of advance of the parts, this allows the base powder, detached from the part, preferably falls into the container adjacent to the inlet.
  • the sieving of the powder from the input-output modules by two sieves also ensuring the separation of the magnetic particles allows the polluted powder from the input module not to mix with the clean powder from the output module.
  • the magnetic particle separation device also ensures the lateral transfer of the powder between the sieve shaker and the powder half-tank corresponding to the latter.
  • FIG. 4 represents a variant in which the second cabin comprises a powder ionizer compartment D formed between the two spray half-chambers B2-1 and B2-2 by means of two walls 51, 52 so as to further reduce the exchanges of powder between the half spray chambers.
  • Compartment D comprises two ionizing tubes 49 and 50, the ionizing tips of which are directed towards the axis of travel of the parts to be treated.
  • the whole of this process and device can in particular be used for the application of powder enamel according to the "two-layer-one baking" process on ordinary steel sheet instead of decarburized sheet in the case of the application of 'direct' presentation enamel.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Electrostatic Spraying Apparatus (AREA)

Description

L'invention concerne un procédé et un dispositif de poudrage électrostatique d'objets se déplaçant en continu au moyen d'un convoyeur à travers au moins deux cabines de traitement, notamment dans les cabines décrites dans le document NL-A-79 08 458.The invention relates to a method and a device for electrostatic powdering of objects moving continuously by means of a conveyor through at least two treatment booths, in particular in the booths described in document NL-A-79 08 458.

Ces cabines comportent chacune un module de pulvérisation et deux modules de filtration d'air situés de part et d'autre du module de pulvérisation avec, entre chacun de ces trois modules, un compartiment permettant l'ionisation de la poudre.These cabins each include a spray module and two air filtration modules located on either side of the spray module with, between each of these three modules, a compartment allowing the ionization of the powder.

Dans certains cas il est nécessaire d'appliquer au moins deux couches superposées de poudres différentes, par exemple pour l'émail vitrifié: une couche de fond d'un émail contenant des éléments d'adhérence au support (qui est une tôle ordinaire) et une couche dite de présentation d'un émail contenant des éléments de décor. Une solution connue en soi consiste à placer l'une derrière l'autre deux cabines de poudrage pour réaliser cette opération.In some cases it is necessary to apply at least two superimposed layers of different powders, for example for vitreous enamel: a base layer of an enamel containing elements of adhesion to the support (which is an ordinary sheet) and a so-called enamel presentation layer containing decorative elements. A solution known in itself consists in placing one behind the other two powder booths to carry out this operation.

Les difficultés ou les complications sont nombreuses et présentent un frein au développement du procédé:

  • - la couche de fond doit être très fine pour un émail (environ 20 ,am), très régulière et peu chargée électrostatiquement. Ceci exige habituellement un appareillage mécanique de déplacement vertical alternatif des pistolets de projection.
  • - la couche de présentation ne doit pas être polluée par la couche de fond, de nature chimique très différente. Or, dans la cabine de pulvérisation de la couche de présentation, les jets de poudre ont tendance à enlever de la poudre de fond. Comme le recyclage de la poudre non déposée est intégral, il en résulte une pollution de la couche de présentation.
The difficulties or complications are numerous and present an obstacle to the development of the process:
  • - the base layer must be very thin for an enamel (about 20, am), very regular and not very electrostatically charged. This usually requires mechanical equipment for the vertical displacement of the spray guns.
  • - the presentation layer must not be polluted by the base layer, which is of very different chemical nature. However, in the spray booth of the presentation layer, the powder jets tend to remove background powder. As the recycling of the non-deposited powder is complete, this results in pollution of the presentation layer.

Une solution connue consiste à pulvériser la couche de présentation en deux temps, avec également des déplacements verticaux alternatifs des pistolets de projection:

  • -premier temps=pulvérisation de poudre recyclée uniquement,
  • -deuxième temps=pulvérisation de poudre neuve uniquement.
A known solution consists in spraying the presentation layer in two stages, also with alternative vertical displacements of the spray guns:
  • -first time = spraying of recycled powder only,
  • -second time = spraying of new powder only.

Cette solution présente plusieures inconvénients:

  • - compte tenu du fort taux de recyclage de la poudre, notamment en émail, la quantité de poudre neuve à envoyer peut être faible et risque, dans ce cas, de mal masquer la couche de poudre recyclée polluée, déposée dans le premier temps,
  • - la poudre neuve et la poudre recyclée possèdent, en émail, des caractéristiques électriques différentes, ce qui peut entraîner des inconvénients à leur pulvérisation séparée notamment le risque de défaut appelé contre-émission.
This solution has several disadvantages:
  • - taking into account the high recycling rate of the powder, in particular enamel, the quantity of new powder to be sent can be low and risks, in this case, of badly masking the layer of polluted recycled powder, deposited at first,
  • - The new powder and the recycled powder have, in enamel, different electrical characteristics, which can cause disadvantages to their separate spraying, in particular the risk of defect called counter-emission.

La présente invention a pour but de pallier ces inconvénients et complications en présentant un procédé et un dispositif d'une grande fiabilité et d'un faible prix de réalisation, notamment en évitant tous les équipements mécaniques qui augmentent les frais de maintenance.The present invention aims to overcome these drawbacks and complications by presenting a method and a device of high reliability and low cost of realization, in particular by avoiding all mechanical equipment which increases the maintenance costs.

L'invention a pour objet un procédé de poudrage électrostatique d'objets se déplaçant en continu, au moyen d'un convoyeur, à travers au moins deux cabines de traitement, dans lequel dans la première cabine on dépose une couche mince, dite couche de fond ou de masse, et dans la cabine suivante une couche plus épaisse, dite couche de présentation, caractérisé par le fait que lesdits objets traversent successivement, dans la première cabine, une enceinte d'ionisation, une enceinte de dispersion de poudre sans chargement électrostatique de celle-ci, une seconde enceinte d'ionisation, le dépôt de poudre intervenant principalement dans les enceintes d'ionisation situées de part et d'autre de l'enceinte de dispersion et non dans l'enceinte de dispersion, puis, dans la deuxième cabine, une enceinte d'ionisation et une enceinte de pulvérisation électrostatique, le dépôt de poudre dans la seconde cabine intervenant dans ces deux enceintes.The subject of the invention is a method of electrostatic powdering of objects moving continuously, by means of a conveyor, through at least two treatment booths, in which in the first booth is deposited a thin layer, called layer of bottom or mass, and in the next cabin a thicker layer, called presentation layer, characterized in that said objects pass successively, in the first cabin, an ionization enclosure, a powder dispersion enclosure without electrostatic charging therefrom, a second ionization enclosure, the powder deposition intervening mainly in the ionization enclosures situated on either side of the dispersion enclosure and not in the dispersion enclosure, then, in the second cabin, an ionization enclosure and an electrostatic spray enclosure, the deposition of powder in the second cabin intervening in these two enclosures.

L'invention a également pour objet un dispositif de poudrage électrostatique d'objets se déplaçant en continu au moyen d'un convoyeur à travers au moins deux cabines de traitement comportant chacune un module de pulvérisation de poudre encadré par des modules de filtration d'air, caractérisé par le fait que le module de pulvérisation de la première cabine comporte une chambre de pulvérisation non électrostatique disposée entre deux compartiments d'ionisation, et que le module de pulvérisation de la cabine suivant la première cabine comporte une chambre de pulvérisation électrostatique précédée par un compartiment d'ionisation.The invention also relates to an electrostatic powdering device for objects moving continuously by means of a conveyor through at least two treatment booths each comprising a powder spraying module framed by air filtration modules. , characterized in that the spray module of the first cabin comprises a non-electrostatic spray chamber disposed between two ionization compartments, and that the spray module of the cabin following the first cabin comprises an electrostatic spray chamber preceded by an ionization compartment.

L'invention va être précisée par la description donnée ci-après d'un mode préféré de réalisation de l'invention en référence au dessin annexé dans lequel:

  • - la figure 1 est une vue en élévation des deux cabines successives sous le convoyeur de transport des pièces. La cabine de couche de fond, ou première cabine, est située à gauche et la cabine de couche de présentation, ou deuxième cabine, est située à droite, selon le sens de déplacement des pièces 1 figuré par la flèche.
  • - la figure 2 est une vue en élévation et en coupe de la seconde cabine selon l'invention comportant deux compartiments de pulvérisation contigus et deux tamiseuses disposées dans des compartiments adjacents aux compartiments de pulvérisation.
  • - la figure 3 est une vue de dessus de la cabine selon la figure 2.
  • - la figure 4 représente une vue de dessus partielle d'une cabine comportant un compartiment d'ionisation intercalé entre les deux compartiments de pulvérisation.
  • - la figure 5 est une vue en coupe transversale d'une tamiseuse séparatrice de particules magnétiques.
  • - la figure 6 est une vue partielle de dessus de la figure 5.
The invention will be clarified by the description given below of a preferred embodiment of the invention with reference to the appended drawing in which:
  • - Figure 1 is an elevational view of the two successive cabins under the parts conveyor. The base layer cabin, or first cabin, is located on the left and the presentation layer cabin, or second cabin, is located on the right, according to the direction of movement of the parts 1 shown by the arrow.
  • - Figure 2 is an elevational and sectional view of the second cabin according to the in vention comprising two contiguous spray compartments and two sieve shakers arranged in compartments adjacent to the spray compartments.
  • FIG. 3 is a top view of the cabin according to FIG. 2.
  • - Figure 4 shows a partial top view of a cabin comprising an ionization compartment interposed between the two spray compartments.
  • - Figure 5 is a cross-sectional view of a sieve separator of magnetic particles.
  • - Figure 6 is a partial top view of Figure 5.

Dans la forme de réalisation représentée sur les figures, des pièces 1 transportées par un convoyeur 2 traversent deux cabines de poudrage comportant chacune trois modules A, B, C:

  • -A1, B1, C1 pour la première cabine,
  • -A2, B2, C2 pour la seconde cabine.
In the embodiment shown in the figures, parts 1 transported by a conveyor 2 pass through two powder coating booths each comprising three modules A, B, C:
  • -A1, B1, C1 for the first cabin,
  • -A2, B2, C2 for the second cabin.

Le module A sert de sas d'entrée, le module B est l'enceinte de pulvérisation destinée au dépôt de poudre et contient des éléments de projection 22 (figure 2) et le module C est le sas de sortie. Le module B2 est divisé par une cloison 48 en deux compartiments de pulvérisation B2-1 et B2-2. Le module B1 ne diffère du module B2 que par l'absence de cette cloison. Les modules d'entrée-sortie A et C contiennent des filtres cylindriques verticaux 5, par exemple au nombre de quatre par module. Un ventilateur 8 permet l'aspiration à travers les filtres et une unité de décolmatage (non représentée) assure la régénération des filtres.Module A serves as an entry airlock, module B is the spray enclosure intended for depositing powder and contains projection elements 22 (FIG. 2) and module C is the exit airlock. The module B2 is divided by a partition 48 into two spray compartments B2-1 and B2-2. The module B1 differs from the module B2 only in the absence of this partition. The input-output modules A and C contain vertical cylindrical filters 5, for example four in number per module. A fan 8 allows the suction through the filters and a cleaning unit (not shown) ensures the regeneration of the filters.

Un élément de fluidisation 3 situé à la base des filtres permet de récupérer la poudre qui tombe de ces filtres et de la retourner dans une réserve de poudre 11, 12 située à la base des compartiments B2-1, B2-2 de la cabine. Ces derniers contiennet une unité de fluidisation 9.A fluidization element 3 located at the base of the filters makes it possible to recover the powder which falls from these filters and to return it to a powder reserve 11, 12 situated at the base of the compartments B2-1, B2-2 of the cabin. These contain a fluidization unit 9.

Les éléments de dépôt de poudre 22 sont de type quelconque, par exemple pistolets de projection électrostatique ou non. Les éléments de dépôt de poudre 22 sont raccordés à des plongeurs 10 qui puisent directement la poudre dans un des bacs de réserve de poudre 11, 12, un bac pour chaque compartiment de pulvérisation. Les éléments 22 sont coiffés d'un capot empêchant l'accumulation de poudre sur ceux- ci.The powder deposition elements 22 are of any type, for example spray guns, electrostatic or not. The powder deposition elements 22 are connected to plungers 10 which draw the powder directly from one of the powder reserve tanks 11, 12, a tank for each spraying compartment. The elements 22 are capped with a cover preventing the accumulation of powder thereon.

Chaque module de pulvérisation B1, B2, comporte deux compartiments ioniseurs E, F contigus à la chambre de pulvérisation et aux modules d'entrée et sortie A, C.Each spraying module B1, B2 has two ionizing compartments E, F adjacent to the spraying chamber and to the inlet and outlet modules A, C.

Dans la première cabine le poudre est d'abord dispersée dans une première enceinte B1 et ensuite chargée électrostatiquement dans deux enceintes contigues E et F situées en amont et en aval. Dans la seconde cabine, on préapplique de la poudre uniquement par forces électrostatiques dans le compartiment E avant de pénétrer dans l'enceinte de pulvérisation B2.In the first cabin, the powder is first dispersed in a first enclosure B1 and then electrostatically charged in two contiguous enclosures E and F located upstream and downstream. In the second cabin, powder is pre-applied only by electrostatic forces in compartment E before entering the spraying enclosure B2.

Un compartiment ioniseur est constitué par des parois pleines 13, 14, 15, 16 laissant un passage central 17 pour les pièces à traiter. Ces parois ont pour effet de constituer des obstacles sur la trajet de la poudre et par la de confiner davantage la poudre dans le module de poudrage B en créant une perte de charge importante lors du passage de l'enceinte de poudrage B vers l'enceinte de filtration A ou C. Ces obstacles obligent la poudre qui participe à ce transfer à se diriger vers l'axe central de la cabine et par là vers les pièces qui circulent dans la cabine. La fraction de poudre encore chargée se redépose sur les pièces. Les compartiments ioniseurs E et F comportent, en outre, des éléments ionisants 21, 23, 25, 27 constitués par des tubes isolants disposée verticalement dans la cabine. Ces tubes sont percés de trous traversés par des pointes 29 de façon à laisser un espace entre la pointe et le trou. Les pointes sont fixées dans la paroi du tube opposée au trou suivant une génératrice par un moyen de fixation, tel que clouage ou analogue. Les pointes 29 sont dirigées vers le centre de la cabine, perpendiculairement à l'axe de transfert des pièces et traversent un élément conducteur disposé à l'intérieur du tube et relié à la haute tension. La source de haute tension est un générateur électrostatique qui peut être le même que celui employé pour les pistolets de projection dans le module B; les pointes 29 sont ainsi en contact avec l'élément conducteur qui les porte à un haut potentiel pour réaliser l'ionisation de la poudre. L'élément conducteur est constitué par un ressort hélicoïdal suspendu dans l'axe du tube, entre les spires duquel sont passées les pointes 29. L'élément conducteur pourrait être constitué par une tresse métallique. Les pointes sont disposées suivant une génératrice sur toute la hauteur du tube; on peut espacer, par example, les pointes d'une distance comprise entre 10 mm et 100 mm.An ionizer compartment consists of solid walls 13, 14, 15, 16 leaving a central passage 17 for the parts to be treated. These walls have the effect of constituting obstacles on the path of the powder and thereby further confine the powder in the powdering module B by creating a significant pressure drop during the passage from the powdering chamber B to the chamber. A or C filtration. These obstacles force the powder participating in this transfer to go towards the central axis of the cabin and thereby towards the parts which circulate in the cabin. The fraction of powder still loaded is redeposited on the parts. The ionizing compartments E and F further comprise ionizing elements 21, 23, 25, 27 constituted by insulating tubes arranged vertically in the cabin. These tubes are pierced with holes crossed by spikes 29 so as to leave a space between the spike and the hole. The points are fixed in the wall of the tube opposite the hole according to a generatrix by a fixing means, such as nailing or the like. The tips 29 are directed towards the center of the cabin, perpendicular to the axis of transfer of the parts and pass through a conductive element placed inside the tube and connected to the high voltage. The high voltage source is an electrostatic generator which may be the same as that used for the spray guns in module B; the tips 29 are thus in contact with the conductive element which brings them to a high potential for achieving the ionization of the powder. The conductive element is constituted by a helical spring suspended in the axis of the tube, between the turns from which the tips 29 have passed. The conductive element could be constituted by a metallic braid. The tips are arranged along a generator over the entire height of the tube; one can space, for example, the points of a distance ranging between 10 mm and 100 mm.

Le tube isolant 21 est fermé à une extrémité par un bouchon isolant traversé par le conducteur d'amenée du courant haute tension de façon à éviter des fuites électrostatiques: son autre extrémité est reliée à une alimentation d'air comprimé.The insulating tube 21 is closed at one end by an insulating plug through which the high-voltage current supply conductor passes so as to avoid electrostatic leaks: its other end is connected to a supply of compressed air.

Lors du fonctionnement, les pointes sont portées à un haut potentiel électrique par l'intermédiaire de l'élément conducteur de façon à créer une ionisation de la poudre, et de l'aire.comprimé est envoyé dans le tube. Cet air, en sortant par les trous entourant les pointes, a pour effect d'empêcher les dépôts de poudre sur les pointes, ce qui nuirait à une bonne ionisation de l'aire et de la poudre présente dans le compartiment.During operation, the tips are brought to a high electrical potential via the conductive element so as to create an ionization of the powder, and the compressed area is sent into the tube. This air, exiting through the holes surrounding the tips, has the effect of preventing powder deposits on the tips, which would harm good ionization of the area and of the powder present in the compartment.

Une tamiseuse est disposée dans chaque compartiment ioniseur E, F, à la partie inférieure de ces compartiments, de préférence, du type représenté sur les figures 4 et 5; la tamiseuse comporte une toile métallique 34 collée sur un cadre métallique 35 soumis à des vibrations engendrées par un vibrateur pneumatique 37 par l'intermédiaire d'une équerre 36. La suspension souple de la tamiseuse est assurée par deux bandes de caoutchouc 38 et 39 qui assurent également l'échanchéité au débordement de poudre. Ces bandes sont fixées sur des équerres 40, 41, 42 et 43 qui peuvent glisser longitudinalement dans deux profilés 44 et 45 qui évitent la rétention de poudre. Ceci permet d'enlever les tamiseuses de la cabine pour nettoyage, par simple extraction latérale moyennant deux portes percées dans le module B. La séparation des particules métalliques et le transport de poudre vers les bacs réservoirs 11, 12 constituant le fond du module B sont assurés par une tôle inclinée 46 soumise aux vibrations de la tamiseuse et munie de bandes parallèles de caoutchouc magnétique 47 collées sur la tôle. Ces bandes 47 sont séparées par des intervalles 48 qui permettent l'accumulation des particules magnétiques entre deux nettoyages.A sieve shaker is placed in each ionizer compartment E, F, at the bottom of these compartments, preferably of the type shown in FIGS. 4 and 5; the sieve shaker comprises a wire mesh 34 bonded to a metal frame 35 subjected to vibrations generated by a pneumatic vibrator 37 via a bracket 36. The flexible suspension of the sieve shaker is provided by two rubber bands 38 and 39 which also provide the powder overflow. These bands are fixed on brackets 40, 41, 42 and 43 which can slide longitudinally in two sections 44 and 45 which avoid the retention of powder. This makes it possible to remove the sieves from the cabin for cleaning, by simple lateral extraction by means of two doors drilled in module B. The separation of the metallic particles and the transport of powder to the reservoir tanks 11, 12 constituting the bottom of module B are provided by an inclined sheet 46 subjected to the vibrations of the sieve shaker and provided with parallel strips of magnetic rubber 47 bonded to the sheet. These strips 47 are separated by intervals 48 which allow the accumulation of magnetic particles between two cleanings.

La forme de réalisation de tamiseuse suivant la figure 5 assure une grande efficacité de tamisage et de séparation des particules métalliques de la poudre.The embodiment of the sieve machine according to FIG. 5 ensures a high efficiency of sieving and separation of the metallic particles from the powder.

L'installation décrite offre les avantages suivants: la cabine présente deux compartiments A et C totalement indépendants de filtration de l'air. Ceci permet de traiter séparément et sans les mélanger de la poudre polluée par les décrochements éventuels de poudre de fond (module A2 d'entrée) et de la poudre propre (module C2 de sortie). La cabine présentant une chambre de pulvérisation et un bac réservoir de poudre séparée en deux parties B2-1, B2-2 égales ou inégales, par une paroi 48 située dans un plan perpendiculaire à l'axe d'avancée des pièces, ceci permet à la poudre de fond, détachée de la pièce, de tomber préférentiellement dans le bac contigu à l'entrée.The installation described offers the following advantages: the cabin has two completely independent air filtration compartments A and C. This makes it possible to treat separately and without mixing the powder polluted by any dropouts in the bottom powder (module A2 inlet) and clean powder (module C2 outlet). The cabin having a spraying chamber and a powder reservoir bin separated into two equal or unequal parts B2-1, B2-2, by a wall 48 situated in a plane perpendicular to the axis of advance of the parts, this allows the base powder, detached from the part, preferably falls into the container adjacent to the inlet.

On emploie un débit d'air comprimé dans la demi-chambre de pulvérisation B2-2 contigüe au module de sortie supérieur à celui existant dans la demi-chambre de pulvérisation proche du module d'entrée. Ceci peut être obtenu:

  • - préférentiellement par des pressions d'air d'injection des pompes à poudre alimentant les pistolets, globalement supérieures dans la chambre de sortie,
  • - ou bien par une entrée d'air comprimé additionnel dans cette chambre.
A compressed air flow is used in the spray half-chamber B2-2 contiguous to the outlet module greater than that existing in the spray half-chamber near the inlet module. This can be obtained:
  • - preferably by injection air pressures of the powder pumps supplying the guns, generally higher in the outlet chamber,
  • - or by an additional compressed air inlet in this room.

Le tamisage de la poudre issue des modules d'entrée-sortie par deux tamiseuses assurant également la séparation des particules magnétiques permet à la poudre polluée du module d'entrée de ne pas se mélanger à la poudre propre du module de sortie. Le dispositif de séparation de particules magnétiques assure également le transfert latéral de la poudre entre la tamiseuse et le demi-bac de poudre correspondant à celle-ci.The sieving of the powder from the input-output modules by two sieves also ensuring the separation of the magnetic particles allows the polluted powder from the input module not to mix with the clean powder from the output module. The magnetic particle separation device also ensures the lateral transfer of the powder between the sieve shaker and the powder half-tank corresponding to the latter.

La figure 4 représente une variante dans laquelle la seconde cabine comporte un compartiment ioniseur de poudre D ménagé entre les deux demi-chambres de pulvérisation B2-1 et B2-2 au moyen de deux parois 51, 52 de façon à réduire encore les échanges de poudre entre les demi-chambres de pulvérisation. Le compartiment D comporte deux tubes ioniseurs 49 et 50 dont les pointes ionisantes sont dirigées vers l'axe de défilement des pièces à traiter.FIG. 4 represents a variant in which the second cabin comprises a powder ionizer compartment D formed between the two spray half-chambers B2-1 and B2-2 by means of two walls 51, 52 so as to further reduce the exchanges of powder between the half spray chambers. Compartment D comprises two ionizing tubes 49 and 50, the ionizing tips of which are directed towards the axis of travel of the parts to be treated.

L'ensemble de ce procédé et dispositif peut notamment être utilisé pour l'application d'émail en poudre selon le procédé "deux couches-une cuisson" sur tôle d'acier ordinaire au lieu de tôle décarburée dans le cas de l'application d'émail de présentation "directe".The whole of this process and device can in particular be used for the application of powder enamel according to the "two-layer-one baking" process on ordinary steel sheet instead of decarburized sheet in the case of the application of 'direct' presentation enamel.

Ce procédé peut également être utilisé dans un dispositif tel que décrit dans le document FR-A No. 2 444 508 qui permet la réalisation d'un dégradé de couleur en poudre d'émail. Dans ce cas le dispositif comporte trois cabines successives:

  • - une première cabine pour la couche de fond en émail d'accrochage sur la tôle,
  • - une seconde cabine pour la première couche de présentation, qui dispose des caractéristiques de la cabine de présentation, énoncées ci-dessus,
  • - une troisième cabine pour la seconde couche de présentation, appliquée par l'arrière de la pièce, et qui dispose également des caractéristiques sus-nommées, qui permet d'obtenir un effet de dégradé de couleur.
This method can also be used in a device as described in document FR-A No. 2 444 508 which allows the production of a gradation of color in enamel powder. In this case, the device comprises three successive cabins:
  • - a first cabin for the primer in enamel for attachment to the sheet,
  • - a second cabin for the first presentation layer, which has the characteristics of the presentation cabin, set out above,
  • - a third cabin for the second presentation layer, applied from the back of the room, and which also has the above-mentioned characteristics, which makes it possible to obtain a color gradient effect.

Claims (12)

1. A method for the electrostatic powdering of objects (1) which are moving continuously, by means of a conveyor (2), through two treatment booths, in the first booth a thin layer, called base or mass layer, and in the second booth a thicker layer, called presentation layer, being deposited, characterized in that said objects pass successively in the first booth, through a ionization zone (E), a dispersion zone (B1) for powder which is not charged electrostatically, a second ionization zone (F), the deposition of powder principally taking place in the ionization zones on both sides of the dispersion zone and not in the dispersion zone, then, in the second booth, through a ionisation zone (E) and an electrostatic spraying zone (B2), the deposition of powder in the second booth taking place in these two zones.
2. A method for the electrostatic powdering of objects according to claim 1, characterized in that two successive layers are applied in the booth or booths following the first booth, in the electrostatic spraying zone (B2), said zone being divided into two adjacent compartments (B2-1, B2-2) each corresponding to the deposition of one of these layers, in that an air pressure higher than that of the compartment B2-1 situated more upstream is exerted in the spraying compartment B2-2 situated more downstream and in that a sieving with separation of magnetic particles of the powder up- and downstream of the spraying zone (B2) is executed.
3. A method according to one of the claims 1 and 2, characterized on that at the exit of the electrostatic spraying zone (B2) of the second booth the object passes through a ionization zone.
4. A device for electrostatically powdering objects which are continuously moving by means of a conveyor through at least two treatment booths each comprising a powder spraying module framed by air filter modules, characterized in that the powdering module of the first booth comprises a powdering chamber (B1) for powder which is not electrostatic, disposed between two ionization compartments, and that the spraying module of the booth following the first booth comprises a chamber for electrostatic spraying (B2) preceded by a ionization compartment (E).
5. A device according to claim 4, characterized in that the spraying chamber (B2) comprises two adjacent compartments (B2-1, B2-2), each compartment comprising a distinct powder reserve tank (11, 12), permitting to apply successively two powder layers to the object to be treated, the two compartments comprising a fluidization unit (9), the deposition means (22) situated in the compartments (B2-1, B2-2) being supplied from the tanks 11 and 12 respectively.
6. A device according to claim 5, characterized in that the two compartments (B2-1, B2-2) of the spraying chamber (B2) are contiguous.
7. A device according to claim 5, characterized in that the two compartments (B2-1, B2-2) of the spraying chamber (B2) are separated by a ionization compartment (D).
8. A device according to claim 5, characterized in that the total flow rate of compressed air injected into the downstream spraying compartment (B2-2) is higher than that injected into the upstream spraying compartment (B2-1).
9. A device according to one of claims 4 to 8, characterized in that a ionization zone is provided in the second booth downstream of the electrostatic spraying zone.
10. A device according to one of claims 4 to 9, characterized in that a ionization compartment (E, F) comprises a sieve (34) which separates magnetic particles from the powder.
11. A device according to claim 10, characterized in that the sieve comprises elements for separating magnetic particles from the powder ensuring the transport by vibration between the sieve and a powder reserve tank (11, 12).
12. A device according to one of the claims 10 and 11, characterized in that the sieve comprises elements for magnetic separation constituted by parallel stripes (47) of magnetic indiarubber fixed on a sheet-metal (46) which is vibrated by the sieve, spaces (48) remaining between these stripes being destined to retain magnetic particles.
EP81104290A 1980-06-13 1981-06-04 Method of and apparatus for the electrostatic powdering of objects in several different layers Expired EP0042111B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8013161A FR2484291A1 (en) 1980-06-13 1980-06-13 METHOD AND DEVICE FOR ELECTROSTATIC PULPING OF OBJECTS IN SEVERAL DIFFERENT LAYERS
FR8013161 1980-06-13

Publications (2)

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EP0042111A1 EP0042111A1 (en) 1981-12-23
EP0042111B1 true EP0042111B1 (en) 1984-11-14

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EP81104290A Expired EP0042111B1 (en) 1980-06-13 1981-06-04 Method of and apparatus for the electrostatic powdering of objects in several different layers

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US (2) US4376136A (en)
EP (1) EP0042111B1 (en)
JP (1) JPS5727174A (en)
AR (1) AR226730A1 (en)
BR (1) BR8103756A (en)
DE (1) DE3167167D1 (en)
ES (1) ES502998A0 (en)
FR (1) FR2484291A1 (en)
GR (1) GR74934B (en)
NO (1) NO811974L (en)
SU (1) SU1120919A3 (en)
YU (1) YU137381A (en)

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US4704953A (en) * 1986-11-12 1987-11-10 Nordson Corporation Powder spray system
EP0439670A1 (en) * 1989-12-23 1991-08-07 Columbus System Patent Ag Pretreatment method for metal sheets
DE4013063C1 (en) * 1990-04-24 1992-01-02 Metri Airfluid Ag, Altstaetten, Ch
US5454872A (en) * 1993-07-28 1995-10-03 Nordson Corporation System for controlling and utilizing finer powder particles in a powder coating operation
DE4446089C2 (en) * 1994-12-22 2001-05-10 Eisenmann Kg Maschbau Process for powder coating and painting system for carrying out the process
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US6099898A (en) * 1998-03-20 2000-08-08 Haden, Inc. Method for applying powder paint
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US20080191378A1 (en) * 2007-02-14 2008-08-14 Brian Paul Microsphere reinforcement of composite materials
FR3108044B1 (en) * 2020-03-11 2023-04-28 Exel Ind Base for a powder coating booth

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Also Published As

Publication number Publication date
US4454832A (en) 1984-06-19
US4376136A (en) 1983-03-08
ES8203649A1 (en) 1982-04-01
BR8103756A (en) 1982-03-02
JPS5727174A (en) 1982-02-13
AR226730A1 (en) 1982-08-13
ES502998A0 (en) 1982-04-01
GR74934B (en) 1984-07-12
FR2484291A1 (en) 1981-12-18
DE3167167D1 (en) 1984-12-20
NO811974L (en) 1981-12-14
EP0042111A1 (en) 1981-12-23
FR2484291B1 (en) 1984-11-16
YU137381A (en) 1983-10-31
SU1120919A3 (en) 1984-10-23

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