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EP0707521B1 - Electrostatic spraying device with rotary spray head, for spraying a coating product in powder form - Google Patents

Electrostatic spraying device with rotary spray head, for spraying a coating product in powder form Download PDF

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Publication number
EP0707521B1
EP0707521B1 EP94917699A EP94917699A EP0707521B1 EP 0707521 B1 EP0707521 B1 EP 0707521B1 EP 94917699 A EP94917699 A EP 94917699A EP 94917699 A EP94917699 A EP 94917699A EP 0707521 B1 EP0707521 B1 EP 0707521B1
Authority
EP
European Patent Office
Prior art keywords
spraying device
head
coating product
conduit
spray
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 - Lifetime
Application number
EP94917699A
Other languages
German (de)
French (fr)
Other versions
EP0707521A1 (en
Inventor
Michel Di Gioia
Van Tan Pham
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.)
Sames SA
Original Assignee
Sames SA
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Filing date
Publication date
Application filed by Sames SA filed Critical Sames SA
Publication of EP0707521A1 publication Critical patent/EP0707521A1/en
Application granted granted Critical
Publication of EP0707521B1 publication Critical patent/EP0707521B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
    • B05B5/04—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces
    • B05B5/0418—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces designed for spraying particulate material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
    • B05B5/04—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
    • B05B5/053—Arrangements for supplying power, e.g. charging power
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
    • B05B5/04—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces
    • B05B5/0426—Means for supplying shaping gas

Definitions

  • the invention relates to an electrostatic sprayer of powdery coating product, such as for example a hot-melt paint, comprising a rotary projection head. It relates more particularly to the high voltage supply of the projection head.
  • Rotating electrostatic sprayers of coating product, liquid or in powder form are effective because they combine with centrifugal forces of projection electrical forces to guide the particles of product towards the object to be covered which is kept to the ground. To do this, the product must be electrically charged.
  • the most effective charging means is to bring to a high voltage, such as for example 100 kilovolts, the rotary projection head or a part thereof.
  • this projection head is in motion relative to the body of the projector.
  • the usual rotational speeds which make it possible to obtain a fairly regular projection to guarantee a satisfactory surface condition on the objects to be coated are of the order of several thousand, even several tens of thousands of revolutions per minute.
  • brushes sometimes called pads, have been arranged at the periphery of the shaft supporting the projection head.
  • the peripheral speed of the shaft is 78.5 m / s, or 283 km / h.
  • the invention solves all of these problems.
  • an electrostatic sprayer of powdery coating product comprising a coating product supply duct opening axially at the bottom of a rotary projection head and a high voltage supply circuit of said projection head, characterized in that said circuit includes a axial contact between said projection head and a fixed part carried by said duct.
  • a pin is mounted movable axially on the projection head and is in contact with a conductive part carried by the supply duct.
  • the high voltage can be applied to the axis of rotation of the projection head at a point compatible with the use of a central supply of the projection head with coating product. At the point of contact between the pin and the supply duct, the friction forces are minimal and this contact therefore does not limit the speed of rotation of the projection head.
  • the pin is kept in contact with the conduit by a spring which conducts the high voltage in the deflector of the projection head to the charging electrode.
  • This projector comprises a body 1 in the central part of which is fixed an air-powder mixture supply pipe 2 of a rotary projection head 3.
  • the axis of symmetry XX ′ of the supply pipe 2 is also the axis of rotation of the projection head 3.
  • This projection head consists of an element generally in the form of a bowl 4 and a deflector 5 made integral with a hub 6 by one or more screws 7.
  • the element 4 and the deflector 5 are for example made of plastic.
  • the hub 6 is rotated by a hollow shaft 8 disposed around the supply duct 2.
  • the hollow shaft is integral with the rotor 9 of an air turbine known per se and can rotate around the axis XX 'thanks to two ball bearings 10 and 10'.
  • This turbine is supplied with air by a duct 11.
  • the air which has driven the rotor 9 is discharged towards the projection head in the gap between the hollow shaft 8 and the duct 2. It serves as dilution air for the air-coating product mixture and prevents particles of coating product from going up along the external surface of the duct 2 in the direction of the rotor 9 or the bearings 10 and 10 ′ or from being deposited along this duct. which would be incompatible with operation of the projector with different coating products, such as paints of different colors, due to possible mixtures between the products.
  • a support 20 is fixed to the body 1 by means of one or more screws 21; it is intended to hold in place the end of a high voltage cable not shown.
  • An electrical conductor 22 connects the end of the support 20 to the outer face of the conduit 2 which is conductive, for example covered with a metallic layer 23.
  • the end of the conduit 2 carries a tubular end piece 24 made of conductive, plastic or metallic material , in electrical contact with the metallic layer 23.
  • This endpiece 24 comprises three regularly distributed tabs 25 which meet at the center of the duct 2 to form the support for a conductive patch 26, for example metallic, placed on the axis XX 'of the conduit 2.
  • the circuit formed by the conductor 22, the layer 23, the end piece 24 and a lug 25 makes it possible to supply the pellet 26 with high voltage.
  • the junction zone of the lugs 25 in which the pellet 26 is housed is conical on the side where the air-product mixture arrives in order to present a minimum resistance to the flow of this mixture.
  • legs 25 can be suitably profiled.
  • the deflector 5 carries, on its axis of rotation XX ', a conductive pin 30, for example metallic, kept in contact with the pad 26 under the effect of a spring 31, also conductive.
  • the spring 31 is supported on the front face of the deflector which is constituted by a disc-shaped charging electrode 32. In this way, the high voltage which is transmitted from the pad 26 to the pin 30 is conveyed to the edge of the electrode 32 where the air-coating product mixture is charged when it is sprayed.
  • the deflector 5 is metallic and the charging electrode 32 is formed by the edge of the deflector.
  • the electrode 32 can be embedded in the mass of the deflector 5; the spring 31 is then brought into contact with a part of the electrode 32 by any suitable means.
  • the above construction is such that the point of electrical contact between the pin and the pad 26 is that where the friction is minimal because the tangential speed on the axis XX 'is zero. Contact takes place in the path of the air-powder mixture.
  • the contact surface is cleaned each time that the duct 2 is cleaned, that is to say in particular at each change of color of coating product if the projector is used with several products of different colors.
  • the pin 30 is held in abutment by the spring 31 ensures constant contact between the pin and the pad 26 whatever the degree of tightening of the screws 7 and this, without risk of damaging the pad or the pin in the event of excessive tightening.
  • the pin is susceptible to movements of small amplitude along the axis XX 'to correct any inaccuracies in the assembly.
  • this spring makes it possible to make up for the tolerances inherent in industrial manufacturing: it is not necessary to pair the deflector 5 and the pin 30 with the end piece 24 and the patch. 26.
  • the projection head 3 can thus be changed independently of the end piece 24 during the usual projector maintenance operations.
  • pin 30 and the spring 31 could be mounted on the fixed part in place of the pad 26.

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  • Electrostatic Spraying Apparatus (AREA)

Abstract

Electrostatic spraying device, for spraying a coating product in powder form, comprising a coating product feeding tube (2) opening axially at the bottom of a rotary spray head (3), characterized in that a slug (30), axially mounted on said spray head, is electrically engaged with a fixed portion (26) of the spraying device, the fixed portion being electrically conductive and connected to a high voltage feeding circuit (22, 23, 24, 25). By means of the invention, the high voltage may be applied on the rotation axis (XX') of the spray head at a location compatible with the central feeding of the coating product into the spray head.

Description

L'invention concerne un projecteur électrostatique de produit de revêtement pulvérulent, tel que par exemple une peinture thermofusible, comportant une tête de projection rotative. Elle concerne plus particulièrement l'alimentation en haute tension de la tête de projection.The invention relates to an electrostatic sprayer of powdery coating product, such as for example a hot-melt paint, comprising a rotary projection head. It relates more particularly to the high voltage supply of the projection head.

Les projecteurs rotatifs électrostatiques de produit de revêtement, liquide ou sous forme pulvérulente, sont efficaces car ils associent aux forces centrifuges de projection des forces électriques pour guider les particules de produit vers l'objet à recouvrir qui est maintenu à la terre. Pour ce faire, le produit doit être chargé électriquement. Le moyen de charge le plus efficace consiste à porter à une tension élevée, telle que par exemple 100 kilovolts, la tête de projection rotative ou une partie de celle-ci.Rotating electrostatic sprayers of coating product, liquid or in powder form, are effective because they combine with centrifugal forces of projection electrical forces to guide the particles of product towards the object to be covered which is kept to the ground. To do this, the product must be electrically charged. The most effective charging means is to bring to a high voltage, such as for example 100 kilovolts, the rotary projection head or a part thereof.

Or, cette tête de projection est en mouvement par rapport au corps du projecteur. Les vitesses de rotation usuelles qui permettent d'obtenir une projection assez régulière pour garantir un état de surface satisfaisant sur les objets à revêtir sont de l'ordre de plusieurs milliers, voire plusieurs dizaines de milliers de tours par minute.However, this projection head is in motion relative to the body of the projector. The usual rotational speeds which make it possible to obtain a fairly regular projection to guarantee a satisfactory surface condition on the objects to be coated are of the order of several thousand, even several tens of thousands of revolutions per minute.

Plusieurs techniques ont été envisagées pour transmettre la haute tension à la tête de projection.Several techniques have been considered for transmitting high voltage to the projection head.

On a essayé d'utiliser les roulements à billes qui supportent l'axe de la turbine. Cette solution fonctionne quelques heures, voire quelques jours, mais l'usure inévitable des roulements est telle que les billes ne sont pas toujours en contact avec les deux cages des roulements: le contact électrique n'est pas constant et la tête de projection n'est pas alimentée régulièrement en haute tension. Le nuage de particules de produit de revêtement n'est pas chargé régulièrement et l'état de surface obtenu n'est pas satisfaisant. De plus, une telle méthode n'est pas applicable avec une turbine à paliers à air.We tried to use the ball bearings that support the axis of the turbine. This solution works for a few hours or even a few days, but the inevitable wear of the bearings is such that the balls are not always in contact with the two bearing cages: the electrical contact is not constant and the projection head does not is not regularly supplied with high voltage. The cloud of particles of coating product is not loaded regularly and the surface condition obtained is not satisfactory. In addition, such a method is not applicable with an air bearing turbine.

Dans les projecteurs rotatifs de produit de revêtement liquide, on a parfois utilisé l'arbre supportant la tête de projection en installant un contact électrique à l'arrière de celui-ci, c'est-à-dire du côté opposé à la tête de projection. Un exemple d'une telle réalisation est donné dans le brevet américain US N° 4 700 896.In rotary projectors for liquid coating product, the shaft supporting the projection head has sometimes been used by installing an electrical contact at the rear of the latter, that is to say on the side opposite the head of the projection head. projection. An example of such an embodiment is given in US Pat. No. 4,700,896.

Cette technique n'est pas utilisable avec un projecteur de produit pulvérulent. A la différence d'un produit liquide, un produit pulvérulent n'est pas dirigé vers la tête de projection par un injecteur mais au contraire entraîné par un jet d'air qui dilue aussi le produit. Le diamètre du conduit d'alimentation en produit pulvérulent est de l'ordre de 25 mm. L'alimentation de la tête de projection est nécessairement centrale pour assurer la symétrie du nuage de produit de revêtement pulvérisé par le projecteur. Le dispositif du brevet US N° 4 700 896 n'est alors pas utilisable. En effet, l'arbre supportant la tête de projection est alors creux, il est impossible d'installer un pion sur sa face arrière. De plus, l'extrémité arrière du conduit d'alimentation fixe est connectée au conduit d'amenée du produit de revêtement, ce qui occupe le centre de l'arbre creux.This technique cannot be used with a sprayer of powdery product. Unlike a liquid product, a pulverulent product is not directed towards the projection head by an injector but on the contrary entrained by an air jet which also dilutes the product. The diameter of the pulverulent product supply duct is of the order of 25 mm. The power of the projection head is necessarily central to ensure the symmetry of the cloud of coating product sprayed by the projector. The device of US Pat. No. 4,700,896 is therefore not usable. In fact, the shaft supporting the projection head is then hollow, it is impossible to install a pin on its rear face. In addition, the rear end of the fixed supply duct is connected to the coating product supply duct, which occupies the center of the hollow shaft.

Enfin, des balais, parfois appelés patins, ont été disposés à la périphérie de l'arbre supportant la tête de projection. Pour une vitesse de rotation de 60 000 tours par minute et un arbre de 25 mm de diamètre, la vitesse périphérique de l'arbre est de 78,5 m/s, soit 283 km/h. Ces balais s'usent donc très vite et limitent sensiblement la vitesse de rotation de la tête de projection.Finally, brushes, sometimes called pads, have been arranged at the periphery of the shaft supporting the projection head. For a rotation speed of 60,000 revolutions per minute and a shaft 25 mm in diameter, the peripheral speed of the shaft is 78.5 m / s, or 283 km / h. These brushes therefore wear out very quickly and significantly limit the speed of rotation of the projection head.

L'invention résout l'ensemble de ces problèmes.The invention solves all of these problems.

Elle concerne un projecteur électrostatique de produit de revêtement pulvérulent comportant un conduit d'alimentation en produit de revêtement débouchant axialement au fond d'une tête de projection rotative et un circuit d'alimentation en haute tension de ladite tête de projection, caractérisé en ce que ledit circuit comporte un contact axial entre ladite tête de projection et une partie fixe portée par ledit conduit.It relates to an electrostatic sprayer of powdery coating product comprising a coating product supply duct opening axially at the bottom of a rotary projection head and a high voltage supply circuit of said projection head, characterized in that said circuit includes a axial contact between said projection head and a fixed part carried by said duct.

Selon un mode possible de réalisation de l'invention, un pion est monté mobile axialement sur la tête de projection et est en contact avec une partie conductrice portée par le conduit d'alimentation. La haute tension peut être appliquée sur l'axe de rotation de la tête de projection en un point compatible avec l'utilisation d'une alimentation centrale de la tête de projection en produit de revêtement. Au point de contact entre le pion et le conduit d'alimentation les forces de frottement sont minimales et ce contact ne limite donc pas la vitesse de rotation de la tête de projection. Le pion est maintenu en contact avec le conduit grâce à un ressort qui conduit la haute tension dans le déflecteur de la tête de projection jusqu'à l'électrode de charge.According to a possible embodiment of the invention, a pin is mounted movable axially on the projection head and is in contact with a conductive part carried by the supply duct. The high voltage can be applied to the axis of rotation of the projection head at a point compatible with the use of a central supply of the projection head with coating product. At the point of contact between the pin and the supply duct, the friction forces are minimal and this contact therefore does not limit the speed of rotation of the projection head. The pin is kept in contact with the conduit by a spring which conducts the high voltage in the deflector of the projection head to the charging electrode.

L'invention sera mieux comprise et d'autres avantages de celle-ci apparaîtront plus clairement à la lumière de la description qui va suivre d'un mode de réalisation d'un projecteur de produit de revêtement pulvérulent conforme à son principe donnée uniquement à titre d'exemple et faite en référence à la figure annexée qui est une vue schématique partielle en coupe d'un projecteur selon l'invention.The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of an embodiment of a sprayer of powder coating product conforming to its principle given solely by way of example and made with reference to the attached figure which is a partial schematic sectional view of a projector according to the invention.

Ce projecteur comporte un corps 1 dans la partie centrale duquel est fixé un conduit d'alimentation en mélange air-poudre 2 d'une tête de projection rotative 3. L'axe de symétrie XX' du conduit d'alimentation 2 est aussi l'axe de rotation de la tête de projection 3. Cette tête de projection est constituée d'un élément globalement en forme de bol 4 et d'un déflecteur 5 rendus solidaires d'un moyeu 6 par une ou plusieurs vis 7. L'élément 4 et le déflecteur 5 sont par exemple en matière plastique. Le moyeu 6 est entraîné en rotation par un arbre creux 8 disposé autour du conduit d'alimentation 2.This projector comprises a body 1 in the central part of which is fixed an air-powder mixture supply pipe 2 of a rotary projection head 3. The axis of symmetry XX ′ of the supply pipe 2 is also the axis of rotation of the projection head 3. This projection head consists of an element generally in the form of a bowl 4 and a deflector 5 made integral with a hub 6 by one or more screws 7. The element 4 and the deflector 5 are for example made of plastic. The hub 6 is rotated by a hollow shaft 8 disposed around the supply duct 2.

L'arbre creux est solidaire du rotor 9 d'une turbine a air connue en soi et peut tourner autour de l'axe XX' grâce a deux roulements à billes 10 et 10'. Cette turbine est alimentée en air par un conduit 11. L'air qui a entrainé le rotor 9 est évacué vers la tête de projection dans l'interstice entre l'arbre creux 8 et le conduit 2. Il sert d'air de dilution pour le mélange air-produit de revêtement et évite que des particules de produit de revêtement ne remontent le long de la surface extérieure du conduit 2 en direction du rotor 9 ou des roulements 10 et 10' ou ne se déposent le long de ce conduit, ce qui serait incompatible avec un fonctionnement du projecteur avec des produits de revêtement différents, tels que des peintures de différentes couleurs, à cause des mélanges possibles entre les produits.The hollow shaft is integral with the rotor 9 of an air turbine known per se and can rotate around the axis XX 'thanks to two ball bearings 10 and 10'. This turbine is supplied with air by a duct 11. The air which has driven the rotor 9 is discharged towards the projection head in the gap between the hollow shaft 8 and the duct 2. It serves as dilution air for the air-coating product mixture and prevents particles of coating product from going up along the external surface of the duct 2 in the direction of the rotor 9 or the bearings 10 and 10 ′ or from being deposited along this duct. which would be incompatible with operation of the projector with different coating products, such as paints of different colors, due to possible mixtures between the products.

Un support 20 est fixé sur le corps 1 au moyen d'une ou plusieurs vis 21; il est destiné à maintenir en place l'extrémité d'un câble haute tension non représenté. Un conducteur électrique 22 relie l'extrémité du support 20 à la face extérieure du conduit 2 qui est conductrice, par exemple recouverte d'une couche métallique 23. L'extrémité du conduit 2 porte un embout tubulaire 24 en matériau conducteur, plastique ou métallique, en contact électrique avec la couche métallique 23. Cet embout 24 comprend trois pattes 25 régulièrement réparties gui se rejoignent au centre du conduit 2 pour constituer le support d'une pastille 26 conductrice, par exemple métallique, placée sur l'axe XX' du conduit 2. Le circuit constitué par le conducteur 22, la couche 23, l'embout 24 et une patte 25 permet d'alimenter en haute tension la pastille 26. La zone de jonction des pattes 25 dans laquelle est logée la pastille 26 est conique du côté où arrive le mélange air-produit afin de présenter une résistance minimum à l'écoulement de ce mélange.A support 20 is fixed to the body 1 by means of one or more screws 21; it is intended to hold in place the end of a high voltage cable not shown. An electrical conductor 22 connects the end of the support 20 to the outer face of the conduit 2 which is conductive, for example covered with a metallic layer 23. The end of the conduit 2 carries a tubular end piece 24 made of conductive, plastic or metallic material , in electrical contact with the metallic layer 23. This endpiece 24 comprises three regularly distributed tabs 25 which meet at the center of the duct 2 to form the support for a conductive patch 26, for example metallic, placed on the axis XX 'of the conduit 2. The circuit formed by the conductor 22, the layer 23, the end piece 24 and a lug 25 makes it possible to supply the pellet 26 with high voltage. The junction zone of the lugs 25 in which the pellet 26 is housed is conical on the side where the air-product mixture arrives in order to present a minimum resistance to the flow of this mixture.

De même, les pattes 25 peuvent être profilées de façon adéquate.Likewise, the legs 25 can be suitably profiled.

D'autre part, le déflecteur 5 porte, sur son axe de rotation XX', un pion 30 conducteur, par exemple métallique, maintenu en contact avec la pastille 26 sous l'effet d'un ressort 31, conducteur lui aussi. Le ressort 31 est en appui sur la face avant du déflecteur qui est constituée par une électrode de charge en forme de disque 32. De la sorte, la haute tension qui est transmise de la pastille 26 au pion 30 est acheminée jusqu'à l'arête de l'électrode 32 où s'effectue la charge du mélange air-produit de revêtement au moment de sa pulvérisation.On the other hand, the deflector 5 carries, on its axis of rotation XX ', a conductive pin 30, for example metallic, kept in contact with the pad 26 under the effect of a spring 31, also conductive. The spring 31 is supported on the front face of the deflector which is constituted by a disc-shaped charging electrode 32. In this way, the high voltage which is transmitted from the pad 26 to the pin 30 is conveyed to the edge of the electrode 32 where the air-coating product mixture is charged when it is sprayed.

Selon une variante de l'invention, le déflecteur 5 est métallique et l'électrode de charge 32 est constituée par le bord du déflecteur. Selon une autre variante, l'électrode 32 peut être noyée dans la masse du déflecteur 5; le ressort 31 est alors mis en contact avec une partie de l'électrode 32 par tout moyen adapté.According to a variant of the invention, the deflector 5 is metallic and the charging electrode 32 is formed by the edge of the deflector. According to another variant, the electrode 32 can be embedded in the mass of the deflector 5; the spring 31 is then brought into contact with a part of the electrode 32 by any suitable means.

La construction ci-dessus est telle que le point de contact électrique entre le pion et la pastille 26 est celui où les frottements sont minimaux car la vitesse tangentielle sur l'axe XX' est nulle. Le contact a lieu dans le trajet du mélange air-poudre. La surface de contact est nettoyée chaque fois que l'on nettoie le conduit 2, c'est-à-dire en particulier à chaque changement de couleur de produit de revêtement si le projecteur est utilisé avec plusieurs produits de couleurs différentes.The above construction is such that the point of electrical contact between the pin and the pad 26 is that where the friction is minimal because the tangential speed on the axis XX 'is zero. Contact takes place in the path of the air-powder mixture. The contact surface is cleaned each time that the duct 2 is cleaned, that is to say in particular at each change of color of coating product if the projector is used with several products of different colors.

Le fait que le pion 30 est maintenu en appui par le ressort 31 permet d'assurer un contact constant entre le pion et la pastille 26 quel que soit le degré de serrage des vis 7 et ce, sans risque de détérioration de la pastille ou du pion en cas de serrage trop important. Le pion est susceptible de mouvements de faible amplitude le long de l'axe XX' pour corriger les imprécisions éventuelles du montage. De plus, ce ressort permet de rattraper les tolérances inhérentes à une fabrication industrielle: il n'est pas nécessaire d'apparier le déflecteur 5 et le pion 30 à l'embout 24 et à la pastille 26. La tête de projection 3 peut ainsi être changée indépendamment de l'embout 24 lors des opérations usuelles de maintenance du projecteur.The fact that the pin 30 is held in abutment by the spring 31 ensures constant contact between the pin and the pad 26 whatever the degree of tightening of the screws 7 and this, without risk of damaging the pad or the pin in the event of excessive tightening. The pin is susceptible to movements of small amplitude along the axis XX 'to correct any inaccuracies in the assembly. In addition, this spring makes it possible to make up for the tolerances inherent in industrial manufacturing: it is not necessary to pair the deflector 5 and the pin 30 with the end piece 24 and the patch. 26. The projection head 3 can thus be changed independently of the end piece 24 during the usual projector maintenance operations.

Bien entendu, le pion 30 et le ressort 31 pourraient être montés sur la partie fixe à la place de la pastille 26.Of course, the pin 30 and the spring 31 could be mounted on the fixed part in place of the pad 26.

Claims (10)

  1. Electrostatic spraying device for powder coating product comprising a supply conduit (2) for the coating product discharging axially at the rear of a rotary spray-head (3) and a circuit to feed high voltage to said spray-head, characterised in that said circuit (22, 23, 24, 25, 26, 30, 31, 32) comprises an axial contact between said spray-head and a fixed part (26) carried by said conduit.
  2. Spraying device according to claim 1, characterised in that the spray-head (3) comprises a deflector (5), the edge of which forms or carries a charging electrode (32).
  3. Spraying device according to claim 1, characterised in that said axial contact is created by a stud (30) mounted axially on said spray-head in electrical contact with a fixed part (26) of said spraying device, said fixed part being electrically conductive.
  4. Spraying device according to claim 3, characterised in that the electrical contact between the stud (30) and the fixed part (26) is made in the trajectory of the coating product.
  5. Spraying device according to claim 3, characterised in that the stud (30) is capable of a small amount of movement along the axis of rotation (XX') of the spray-head.
  6. Spraying device according to one of claims 3 to 5, characterised in that a spring (31) is disposed between the stud (30) and the charging electrode (32).
  7. Spraying device according to claim 6, characterised in that the spring (31) ensures electrical contact between the stud (30) and the charging electrode (32).
  8. Spraying device according to claim 3, characterised in that the supply conduit (2) is equipped with a contact capsule (26) for the stud (30), said capsule being disposed on the axis of rotation (XX') of the spray-head (3) and held in position by at least one arm (25) of electrically conductive material connected to said conduit.
  9. Spraying device according to claim 1, characterised in that the outer surface of the supply conduit is of an electrically conductive material or is covered by a conductive film (23).
  10. Spraying device according to claim 1, characterised in that said conduit comprises a conductive film (23) disposed on the outer surface of the supply conduit (2) and a conductive tubular nozzle (24) disposed at the end of said conduit, said nozzle disposed at the end of said conduit, said nozzle being in electrical contact with said film and consisting of at least one conductive arm (25) forming the support for said fixed part (26).
EP94917699A 1993-06-17 1994-06-01 Electrostatic spraying device with rotary spray head, for spraying a coating product in powder form Expired - Lifetime EP0707521B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR9307296A FR2706328B1 (en) 1993-06-17 1993-06-17 Electrostatic powder coating product projector with a rotating projection head.
FR9307296 1993-06-17
PCT/FR1994/000638 WO1995000250A1 (en) 1993-06-17 1994-06-01 Electrostatic spraying device with rotary spray head, for spraying a coating product in powder form

Publications (2)

Publication Number Publication Date
EP0707521A1 EP0707521A1 (en) 1996-04-24
EP0707521B1 true EP0707521B1 (en) 1997-02-19

Family

ID=9448225

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94917699A Expired - Lifetime EP0707521B1 (en) 1993-06-17 1994-06-01 Electrostatic spraying device with rotary spray head, for spraying a coating product in powder form

Country Status (7)

Country Link
EP (1) EP0707521B1 (en)
JP (1) JPH09502123A (en)
KR (1) KR960703039A (en)
DE (1) DE69401777T2 (en)
ES (1) ES2098150T3 (en)
FR (1) FR2706328B1 (en)
WO (1) WO1995000250A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030080206A1 (en) 2001-03-08 2003-05-01 Thomas Duerr Powder bell purge tube

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3536580A (en) * 1967-10-13 1970-10-27 Ransburg Electro Coating Corp Paper making methods and apparatus involving electrostatic spray coating
US3572589A (en) * 1968-07-31 1971-03-30 Edward O Norris Electrostatically driven distributor
JPS57144053A (en) * 1981-03-04 1982-09-06 Toyota Motor Corp Rotary atomizing electrostatic coating device
GB2142844A (en) * 1983-07-05 1985-01-30 Edward Julius Bals Sprayers

Also Published As

Publication number Publication date
DE69401777D1 (en) 1997-03-27
FR2706328B1 (en) 1995-09-29
ES2098150T3 (en) 1997-04-16
JPH09502123A (en) 1997-03-04
KR960703039A (en) 1996-06-19
DE69401777T2 (en) 1997-09-04
FR2706328A1 (en) 1994-12-23
EP0707521A1 (en) 1996-04-24
WO1995000250A1 (en) 1995-01-05

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