EP0454548B1 - Device for centrifugally spraying a coating material, more particularly for electrostatic spray coating - Google Patents

Device for centrifugally spraying a coating material, more particularly for electrostatic spray coating Download PDF

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Publication number
EP0454548B1
EP0454548B1 EP91401044A EP91401044A EP0454548B1 EP 0454548 B1 EP0454548 B1 EP 0454548B1 EP 91401044 A EP91401044 A EP 91401044A EP 91401044 A EP91401044 A EP 91401044A EP 0454548 B1 EP0454548 B1 EP 0454548B1
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EP
European Patent Office
Prior art keywords
reflection surface
axis
disc
rear cavity
frustoconical
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
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EP91401044A
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German (de)
French (fr)
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EP0454548A1 (en
Inventor
Gérard Degli
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Sames SA
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Sames SA
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    • 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
    • B05B5/0403—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces characterised by the rotating member
    • B05B5/0407—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces characterised by the rotating member with a spraying edge, e.g. like a cup or a bell
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B15/00—Details of spraying plant or spraying apparatus not otherwise provided for; Accessories
    • B05B15/50—Arrangements for cleaning; Arrangements for preventing deposits, drying-out or blockage; Arrangements for detecting improper discharge caused by the presence of foreign matter
    • B05B15/55—Arrangements for cleaning; Arrangements for preventing deposits, drying-out or blockage; Arrangements for detecting improper discharge caused by the presence of foreign matter using cleaning fluids
    • B05B15/555—Arrangements for cleaning; Arrangements for preventing deposits, drying-out or blockage; Arrangements for detecting improper discharge caused by the presence of foreign matter using cleaning fluids discharged by cleaning nozzles

Definitions

  • the invention relates to a device for centrifugal spraying of a coating product such as a paint or a varnish, in particular for electrostatic application of this product; it relates more particularly to an improvement of the rotating member allowing rapid and effective cleaning of the latter.
  • a device for centrifugal spraying of a liquid coating product, comprising a generally rotating member in the form of a bowl, driven in rotation at high speed about its main axis of symmetry.
  • the bowl-shaped part is connected to a hub by an internal veil arranged generally perpendicular to the axis of rotation.
  • This veil divides the internal space of the bowl into two cavities: a front cavity, open in the direction of projection and a rear cavity surrounding at least the largest part of the hub and in which are arranged, fixed and offset with respect to said rotating member. , a coating product ejection nozzle and a cleaning product ejection nozzle. These two nozzles are directed towards the internal face of the veil.
  • the latter has passages formed at its outer periphery (most often a series of small diameter holes arranged along a circle) to allow the flow, under the effect of centrifugal force, of the coating product along from the wall of the internal surface of the bowl, to the edge of the latter where it is sprayed into fine droplets.
  • the rotating member is, in principle, cleaned by projecting onto the veil the cleaning product which is conveyed towards the edge of the bowl by taking the same path as the coating product.
  • the front of the web is not wetted by the coating product and should therefore remain clean.
  • this front face is gradually covered with droplets of poorly liquid coating product, probably due to the violent atmospheric vortices which exist at the front of the bowl due to its rotation at high speed.
  • droplets can be projected by electrostatic forces towards the objects to be covered. They can also move under the action of centrifugal force towards the spraying edge of the bowl where they cause the projection of large droplets of coating product on objects. Consequently, these deposits on the front face of the veil end up causing unacceptable irregularities on the objects to be covered.
  • the invention provides a new type of device for centrifugal spraying of a coating product, remarkable in that the conformation of the rotating member and more particularly of the aforementioned veil, allows dividing the jet of cleaning product into several parts flowing in different directions making it possible to clean all the surfaces of the bowl and in particular the entire front face of the veil.
  • the invention relates more precisely to a device for centrifugal spraying of a coating product, of the type comprising a rotating member, generally in the form of a bowl, provided with an internal veil extending essentially perpendicularly to the axis of rotation of said member.
  • this veil defining inside said bowl a front cavity open in the direction of projection and a rear cavity enveloping said hub, device in which a product ejection nozzle coating and a cleaning product ejection nozzle are housed in said rear cavity and both directed towards said web and in which passages are provided at the outer periphery of said web in the vicinity of said interior surface, characterized in that said sail has an annular recess communicating with said rear cavity and in which a surface is defined of reflection to return part of a jet of liquid to the central part of said veil and in that said nozzle for ejecting cleaning product is oriented towards this reflection surface.
  • the reflection surface mentioned above is a generally concave surface having its concavity turned towards the aforementioned rear cavity while its central part opens into the front cavity.
  • This reflection surface can for example be frustoconical.
  • FIG. 1 show a part of a centrifugal spraying device 11 for the electrostatic application of a coating product, more particularly the rotating member 12 thereof, generally in the form of a bowl, here with a wall frustoconical and driven in rotation about its main axis of symmetry x'x materialized by a rotary shaft 13 driven in rotation at high speed by means not shown, such as for example a turbine.
  • the rotating member comprises an axial hub 15 fixed to the shaft 13 and the bowl 12 a , constituting its outer part, is connected to the hub by an internal veil 16 extending essentially perpendicularly to the axis x'x.
  • This veil therefore divides the interior of the bowl into a front cavity 17, open in the direction of projection of the coating product and a rear cavity 18 open towards the rear of the device and enveloping both the hub 15 and the shaft 13
  • This rear cavity 18 also houses a coating product ejection nozzle 20 and a cleaning product ejection nozzle 22. These two nozzles are fixed relative to the rotating member and are both directed towards the web 16.
  • the latter comprises passages, in this case holes 24 of small diameter, defined at its periphery at vicinity of its connection zone to the internal surface 26 of said bowl 12 a .
  • the surface 26 being divergent in the direction of projection, the coating material ejected at a certain speed of the nozzle 20 strikes the inner surface 16a of web 16 and flows in the film toward the holes 24, and passes through the progresses on the surface 26 to the spraying edge 28 where it is projected in fine droplets towards an object to be covered.
  • the two nozzles 20 and 22 are offset but, in the example shown, oriented parallel to the axis x'x.
  • the nozzle 20 is farther from the axis x'x than the nozzle 22.
  • the diameter of the nozzle of the nozzle 22 is here smaller than that of the nozzle 20; this arrangement is preferable but identical nozzles can be used.
  • the web 16 comprises an annular recess 30 communicating with the rear cavity 18 here by holes 32 regularly spaced along a circular outline centered on the axis x'x.
  • the recess 30 is shaped to define a reflecting surface 34 capable of sending part of a jet of liquid to the end portion 37 of the hub 15, which merges here with the central part of the web.
  • the cleaning product ejection nozzle 22 is oriented towards this surface so that, during the cleaning phase, said cleaning product is projected onto said reflection surface through the holes 32.
  • the reflection surface 34 is a generally concave surface (here substantially frustoconical) having its concavity turned towards said rear cavity 18 while its central zone opens into the front cavity 17 through a large circular orifice 36.
  • the end of the hub 15 is slightly set back axially from the plane of the orifice 36. Its front face is conical.
  • the hub 15 is here slightly frustoconical, the diameter of the latter increasing from back to front. In this way, a liquid deposited on the lateral surface of the hub is driven by centrifugal force in the direction tending to move it away from the axis x'x (towards the front), thus protecting the shaft 13 from any contamination.
  • the holes 32 are also frustoconical and oriented so that their larger diameter orifices open into the rear cavity 18.
  • the holes 32 advantageously have the same conicity as the hub 15, which makes it possible to drill them as much as possible.
  • near the lateral surface of the hub tangent to its frustoconical lateral surface.
  • the axis of ejection of the cleaning product has a significant incidence at its point of impact on the reflection surface 34.
  • incidence the angle A between the axis of the nozzle and the generator of the reflection surface, at the point of impact. This incidence will preferably be between 30 and 60 °.
  • the half-angle at the top of the frustoconical surface 34 will be between 15 and 75 ° and preferably between 30 and 60 °. In the example shown, the incidence A and the half-angle at the top of the frustoconical surface 34 are close to 45 °.
  • the speed of flow of the jet of cleaning liquid is between 15 and 50 m / s.
  • the speed of rotation of the rotary member can be chosen within fairly large limits, between 6000 and 60000 rpm. It will preferably be greater than 20,000 rpm.
  • the coating material is ejected with a velocity selected in the nozzle 20 and encounters the face 16 a of the web 16. As explained above, under the effect of centrifugal force, it is moving towards the spray edge 28 passing through the holes 24 at the periphery of the web 16.
  • the coating product supply is cut off and the cleaning product is ejected with a certain speed chosen by the nozzle 22 in the direction of the web 16.
  • the jet of cleaning liquid when it is not intercepted by the side walls of the holes 32 or the face 16 a between these holes , strikes the reflecting surface 34 and a distribution of the cleaning liquid is observed both on the conical part 37 of the hub and, more generally, on all the areas of the web 16.
  • Cleaning liquid also passes through the holes 24. All of the cleaning liquid ends up flowing along the frustoconical wall 26 to the ejection edge 28.
  • the cleaning liquid which strikes the reflecting surface 36 is divided into several fractions.
  • a first fraction little rotated, is reflected by the surface 34 and directed towards the end portion 37 of the hub.
  • the cleaning liquid thus striking the central part of the veil would then flow under the effect of centrifugal force along the conical end 37 before being ejected radially outwards, in the thickness of the veil.
  • Another fraction also little rotated, flows in the direction of the orifice 36 under the action of its strong force of ejection by the nozzle 22. This part then flows along the front face of the web 16 then, along the frustoconical surface 26.
  • a third fraction rotated flows in the thickness of the web in the direction of larger diameter under the action of the axial component of the centrifugal force.
  • This fraction thus passes through the holes 32 rearwardly and radially flows along the face 16a of the web 16 before passing through the holes 24 towards the spraying edge 28.
  • all parts of the bowl receive cleaning liquid, in particular the entire front face of the veil.

Description

L'invention concerne un dispositif de pulvérisation centrifuge d'un produit de revêtement tel qu'une peinture ou un vernis, notamment pour application électrostatique de ce produit; elle se rapporte plus particulièrement à un perfectionnement de l'organe tournant permettant un nettoyage rapide et efficace de ce dernier.The invention relates to a device for centrifugal spraying of a coating product such as a paint or a varnish, in particular for electrostatic application of this product; it relates more particularly to an improvement of the rotating member allowing rapid and effective cleaning of the latter.

On connaît un dispositif de pulvérisation centrifuge d'un produit de revêtement liquide, comportant un organe tournant globalement en forme de bol, entraîné en rotation à grande vitesse autour de son axe principal de symétrie. La partie en forme de bol est raccordée à un moyeu par un voile interne agencé globalement perpendiculairement à l'axe de rotation. Ce voile partage l'espace interne du bol en deux cavités: une cavité avant, ouverte dans la direction de projection et une cavité arrière entourant au moins la plus grande partie du moyeu et dans laquelle sont agencées, fixes et désaxées par rapport audit organe tournant, une buse d'éjection de produit de revêtement et une buse d'éjection de produit de nettoyage. Ces deux buses sont dirigées vers la face interne du voile. Ce dernier comporte des passages ménagés à sa périphérie externe (le plus souvent une série de trous de petit diamètre disposés le long d'un cercle) pour permettre l'écoulement, sous l'effet de la force centrifuge, du produit de revêtement le long de la paroi de la surface interne du bol, jusqu'au bord de ce dernier où il est pulvérisé en fines gouttelettes. L'organe tournant est, en principe, nettoyé en projetant sur le voile le produit de nettoyage qui est acheminé vers le bord du bol en empruntant le même chemin que le produit de revêtement.A device is known for centrifugal spraying of a liquid coating product, comprising a generally rotating member in the form of a bowl, driven in rotation at high speed about its main axis of symmetry. The bowl-shaped part is connected to a hub by an internal veil arranged generally perpendicular to the axis of rotation. This veil divides the internal space of the bowl into two cavities: a front cavity, open in the direction of projection and a rear cavity surrounding at least the largest part of the hub and in which are arranged, fixed and offset with respect to said rotating member. , a coating product ejection nozzle and a cleaning product ejection nozzle. These two nozzles are directed towards the internal face of the veil. The latter has passages formed at its outer periphery (most often a series of small diameter holes arranged along a circle) to allow the flow, under the effect of centrifugal force, of the coating product along from the wall of the internal surface of the bowl, to the edge of the latter where it is sprayed into fine droplets. The rotating member is, in principle, cleaned by projecting onto the veil the cleaning product which is conveyed towards the edge of the bowl by taking the same path as the coating product.

La face avant du voile n'est pas mouillée par le produit de revêtement et devrait par conséquent rester propre. Or, il est connu de l'homme du métier que cette face avant se recouvre progressivement de gouttelettes de produit de revêtement peu liquide, probablement en raison des violents tourbillons atmosphériques qui existent à l'avant du bol par suite de sa rotation à grande vitesse. Ces gouttelettes peuvent être projetées par les forces électrostatiques vers les objets à recouvrir. Elles peuvent aussi se déplacer sous l'action de la force centrifuge vers le bord de pulvérisation du bol où elles provoquent la projection de grosses gouttelettes de produit de revêtement sur les objets. Par conséquent, ces dépôts sur la face avant du voile finissent par provoquer des irrégularités inacceptables sur les objets à recouvrir.The front of the web is not wetted by the coating product and should therefore remain clean. However, it is known to those skilled in the art that this front face is gradually covered with droplets of poorly liquid coating product, probably due to the violent atmospheric vortices which exist at the front of the bowl due to its rotation at high speed. These droplets can be projected by electrostatic forces towards the objects to be covered. They can also move under the action of centrifugal force towards the spraying edge of the bowl where they cause the projection of large droplets of coating product on objects. Consequently, these deposits on the front face of the veil end up causing unacceptable irregularities on the objects to be covered.

Diverses solutions ont déjà été proposées pour résoudre ce problème. Par exemple, le brevet américain US-A-4 275 838 propose un agencement dans lequel une buse extérieure de produit de nettoyage est portée par un organe mobile escamoté pendant une phase de projection. Pendant le nettoyage, cette buse est dirigée vers l'avant du bol. On a aussi proposé d'injecter du produit de nettoyage axialement au centre du voile (brevet allemand DE-A-30 01 209). On a aussi proposé de supprimer purement et simplement la partie centrale en la remplaçant par un tronc de cône creux divergent au fond duquel un produit de nettoyage est injecté par une buse dirigée vers l'axe de rotation. Une telle solution est par exemple décrite dans le brevet français FR-A-2 586 206. On a encore proposé de conformer la partie centrale du voile de façon globalement convexe en dirigeant sur cette dernière, au travers de passages convergents vers l'avant, un jet de produit de nettoyage orienté vers l'axe de rotation. Cette solution est décrite dans le brevet américain US-A-4 505 430.Various solutions have already been proposed to solve this problem. For example, American patent US-A-4,275,838 proposes an arrangement in which an external nozzle of cleaning product is carried by a movable member retracted during a projection phase. During cleaning, this nozzle is directed towards the front of the bowl. It has also been proposed to inject cleaning product axially into the center of the veil (German patent DE-A-30 01 209). It has also been proposed to eliminate the central part altogether by replacing it with a divergent hollow truncated cone at the bottom of which a cleaning product is injected by a nozzle directed towards the axis of rotation. Such a solution is for example described in French patent FR-A-2,586,206. It has also been proposed to conform the central part of the web in a generally convex manner by directing on the latter, through converging passages towards the front, a jet of cleaning product directed towards the axis of rotation. This solution is described in American patent US-A-4,505,430.

Ces dispositifs sont peu efficaces et/ou d'un coût et d'une complexité élevés.These devices are ineffective and / or of high cost and complexity.

L'invention propose un nouveau type de dispositif de pulvérisation centrifuge d'un produit de revêtement, remarquable par le fait que la conformation de l'organe tournant et plus particulièrement du voile précité, permet de diviser le jet de produit de nettoyage en plusieurs parties s'écoulant dans des directions différentes permettant de nettoyer toutes les surfaces du bol et notamment la totalité de la face avant du voile.The invention provides a new type of device for centrifugal spraying of a coating product, remarkable in that the conformation of the rotating member and more particularly of the aforementioned veil, allows dividing the jet of cleaning product into several parts flowing in different directions making it possible to clean all the surfaces of the bowl and in particular the entire front face of the veil.

L'invention concerne plus précisément un dispositif de pulvérisation centrifuge d'un produit de revêtement, du type comportant un organe tournant, globalement en forme de bol, muni d'un voile interne s'étendant essentiellement perpendiculairement à l'axe de rotation dudit organe tournant entre un moyeu d'entraînement et la surface intérieure dudit bol, ce voile définissant à l'intérieur dudit bol une cavité avant ouverte dans la direction de projection et une cavité arrière enveloppant ledit moyeu, dispositif dans lequel une buse d'éjection de produit de revêtement et une buse d'éjection de produit de nettoyage sont logées dans ladite cavité arrière et toutes deux dirigées vers ledit voile et dans lequel des passages sont ménagés à la périphérie extérieure dudit voile au voisinage de ladite surface intérieure, caractérisé en ce que ledit voile comporte un évidement annulaire communiquant avec ladite cavité arrière et dans lequel est définie une surface de réflexion pour renvoyer une partie d'un jet de liquide vers la partie centrale dudit voile et en ce que ladite buse d'éjection de produit de nettoyage est orientée vers cette surface de réflexion.The invention relates more precisely to a device for centrifugal spraying of a coating product, of the type comprising a rotating member, generally in the form of a bowl, provided with an internal veil extending essentially perpendicularly to the axis of rotation of said member. rotating between a drive hub and the inner surface of said bowl, this veil defining inside said bowl a front cavity open in the direction of projection and a rear cavity enveloping said hub, device in which a product ejection nozzle coating and a cleaning product ejection nozzle are housed in said rear cavity and both directed towards said web and in which passages are provided at the outer periphery of said web in the vicinity of said interior surface, characterized in that said sail has an annular recess communicating with said rear cavity and in which a surface is defined of reflection to return part of a jet of liquid to the central part of said veil and in that said nozzle for ejecting cleaning product is oriented towards this reflection surface.

La surface de réflexion citée ci-dessus est une surface globalement concave ayant sa concavité tournée vers la cavité arrière précitée tandis que sa partie centrale débouche dans la cavité avant. Cette surface de réflexion peut par exemple être tronconique. Avec cet agencement, une partie du produit de nettoyage est réfléchie vers la partie centrale du voile essentiellement constituée par l'extrémité du moyeu par lequel l'organe tournant est fixé à l'extrémité d'un arbre rotatif tournant à grande vitesse. Une autre partie du produit de nettoyage projetée sur ladite surface de réflexion poursuit sa course jusqu'au bord de l'orifice par lequel l'évidement annulaire débouche dans ladite cavité avant, assurant ainsi le nettoyage de la partie radialement extérieure de la face avant du voile. La totalité de la face avant du voile est donc efficacement nettoyée.The reflection surface mentioned above is a generally concave surface having its concavity turned towards the aforementioned rear cavity while its central part opens into the front cavity. This reflection surface can for example be frustoconical. With this arrangement, a part of the cleaning product is reflected towards the central part of the web essentially constituted by the end of the hub by which the rotary member is fixed to the end of a rotary shaft rotating at high speed. Another part of the cleaning product sprayed on said reflecting surface continues to run to the edge of the orifice through which the annular recess opens in said front cavity, thus ensuring the cleaning of the radially outer part of the front face of the web. The entire front face of the veil is therefore effectively cleaned.

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 dispositif de pulvérisation centrifuge d'un produit de revêtement, conforme à son principe, donnée uniquement à titre d'exemple et faite en référence aux dessins annexés dans lesquels:

  • la figure 1 représente un dispositif de pulvérisation conforme à l'invention vu selon la coupe I-I de la figure 2; et
  • la figure 2 est une coupe II-II de la figure 1.
The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of a device for centrifugal spraying of a coating product, in accordance with its principle, given solely by way of example and made with reference to the accompanying drawings in which:
  • Figure 1 shows a spray device according to the invention seen in section II of Figure 2; and
  • Figure 2 is a section II-II of Figure 1.

Sur les dessins, on a représenté une partie d'un dispositif de pulvérisation centrifuge 11 pour l'application électrostatique d'un produit de revêtement, plus particulièrement l'organe tournant 12 de celui-ci, globalement en forme de bol, ici à paroi tronconique et entraîné en rotation autour de son axe principal de symétrie x'x matérialisé par un arbre rotatif 13 entraîné en rotation à grande vitesse par des moyens non représentés, tels que par exemple une turbine. L'organe tournant comporte un moyeu axial 15 fixé à l'arbre 13 et le bol 12a, constituant sa partie extérieure, est raccordé au moyeu par un voile interne 16 s'étendant essentiellement perpendiculairement à l'axe x'x. Ce voile partage donc l'intérieur du bol en une cavité avant 17, ouverte dans la direction de projection du produit de revêtement et une cavité arrière 18 ouverte vers l'arrière du dispositif et enveloppant à la fois le moyeu 15 et l'arbre 13. Cette cavité arrière 18 abrite aussi une buse d'éjection de produit de revêtement 20 et une buse d'éjection de produit de nettoyage 22. Ces deux buses sont fixes par rapport à l'organe tournant et sont toutes deux dirigées vers le voile 16. Ce dernier comporte des passages, en l'occurrence des trous 24 de petit diamètre, définis à sa périphérie au voisinage de sa zone de raccordement à la surface intérieure 26 dudit bol 12a. La surface 26 étant divergente dans le sens de projection, le produit de revêtement, éjecté avec une certaine vitesse de la buse 20, vient frapper la surface interne 16a du voile 16 et s'écoule en film vers les trous 24, les traverse et progresse sur la surface 26 jusqu'au bord de pulvérisation 28 où il est projeté en fines gouttelettes vers un objet à recouvrir. Les deux buses 20 et 22 sont désaxées mais, dans l'exemple représenté, orientées parallèlement à l'axe x'x. La buse 20 est plus éloignée de l'axe x'x que la buse 22. Le diamètre de l'ajutage de la buse 22 est ici plus petit que celui de la buse 20; cette disposition est préférable mais des buses identiques peuvent être utilisées.The drawings show a part of a centrifugal spraying device 11 for the electrostatic application of a coating product, more particularly the rotating member 12 thereof, generally in the form of a bowl, here with a wall frustoconical and driven in rotation about its main axis of symmetry x'x materialized by a rotary shaft 13 driven in rotation at high speed by means not shown, such as for example a turbine. The rotating member comprises an axial hub 15 fixed to the shaft 13 and the bowl 12 a , constituting its outer part, is connected to the hub by an internal veil 16 extending essentially perpendicularly to the axis x'x. This veil therefore divides the interior of the bowl into a front cavity 17, open in the direction of projection of the coating product and a rear cavity 18 open towards the rear of the device and enveloping both the hub 15 and the shaft 13 This rear cavity 18 also houses a coating product ejection nozzle 20 and a cleaning product ejection nozzle 22. These two nozzles are fixed relative to the rotating member and are both directed towards the web 16. The latter comprises passages, in this case holes 24 of small diameter, defined at its periphery at vicinity of its connection zone to the internal surface 26 of said bowl 12 a . The surface 26 being divergent in the direction of projection, the coating material ejected at a certain speed of the nozzle 20 strikes the inner surface 16a of web 16 and flows in the film toward the holes 24, and passes through the progresses on the surface 26 to the spraying edge 28 where it is projected in fine droplets towards an object to be covered. The two nozzles 20 and 22 are offset but, in the example shown, oriented parallel to the axis x'x. The nozzle 20 is farther from the axis x'x than the nozzle 22. The diameter of the nozzle of the nozzle 22 is here smaller than that of the nozzle 20; this arrangement is preferable but identical nozzles can be used.

Selon une caractéristique importante de l'invention, le voile 16 comporte un évidement annulaire 30 communiquant avec la cavité arrière 18 ici par des trous 32 régulièrement espacés le long d'un contour circulaire centré sur l'axe x'x. L'évidement 30 est conformé pour définir une surface de réflexion 34 apte à envoyer une partie d'un jet de liquide vers la portion extrême 37 du moyeu 15, laquelle se confond ici avec la partie centrale du voile. La buse d'éjection de produit de nettoyage 22 est orientée vers cette surface de sorte que, en phase de nettoyage, ledit produit de nettoyage est projeté sur ladite surface de réflexion à travers les trous 32.According to an important characteristic of the invention, the web 16 comprises an annular recess 30 communicating with the rear cavity 18 here by holes 32 regularly spaced along a circular outline centered on the axis x'x. The recess 30 is shaped to define a reflecting surface 34 capable of sending part of a jet of liquid to the end portion 37 of the hub 15, which merges here with the central part of the web. The cleaning product ejection nozzle 22 is oriented towards this surface so that, during the cleaning phase, said cleaning product is projected onto said reflection surface through the holes 32.

La surface de réflexion 34 est une surface globalement concave (ici sensiblement tronconique) ayant sa concavité tournée vers ladite cavité arrière 18 tandis que sa zone centrale débouche dans la cavité avant 17 par un large orifice circulaire 36. Dans l'exemple représenté, l'extrémité du moyeu 15 est légèrement en retrait axialement du plan de l'orifice 36. Sa face frontale est conique. De plus, le moyeu 15 est ici légèrement tronconique, le diamètre de ce dernier augmentant d'arrière en avant. De cette façon, un liquide déposé sur la surface latérale du moyeu est entraîné par la force centrifuge dans la direction tendant à l'éloigner de l'axe x'x (vers l'avant), protégeant ainsi l'arbre 13 de toute souillure. Dans l'exemple, les trous 32 sont également tronconiques et orientés de façon que leurs orifices de plus grand diamètre débouchent dans la cavité arrière 18. Les trous 32 ont avantageusement la même conicité que le moyeu 15, ce qui permet de les forer au plus près de la surface latérale du moyeu, tangents à sa surface latérale tronconique. Avec sa surface de réflexion telle que décrite, il est préférable que l'axe d'éjection du produit de nettoyage (issu de la buse 22) présente une incidence notable à son point d'impact sur la surface de réflexion 34. On appelle ici "incidence" l'angle A entre l'axe de la buse et la génératrice de la surface de réflexion, au point d'impact. Cette incidence sera de préférence comprise entre 30 et 60°. Le demi-angle au sommet de la surface tronconique 34 sera compris entre 15 et 75° et de préférence compris entre 30 et 60°. Dans l'exemple représenté, l'incidence A ainsi que le demi-angle au sommet de la surface tronconique 34 sont voisins de 45°.The reflection surface 34 is a generally concave surface (here substantially frustoconical) having its concavity turned towards said rear cavity 18 while its central zone opens into the front cavity 17 through a large circular orifice 36. In the example shown, the end of the hub 15 is slightly set back axially from the plane of the orifice 36. Its front face is conical. In addition, the hub 15 is here slightly frustoconical, the diameter of the latter increasing from back to front. In this way, a liquid deposited on the lateral surface of the hub is driven by centrifugal force in the direction tending to move it away from the axis x'x (towards the front), thus protecting the shaft 13 from any contamination. In the example, the holes 32 are also frustoconical and oriented so that their larger diameter orifices open into the rear cavity 18. The holes 32 advantageously have the same conicity as the hub 15, which makes it possible to drill them as much as possible. near the lateral surface of the hub, tangent to its frustoconical lateral surface. With its reflection surface as described, it is preferable that the axis of ejection of the cleaning product (from the nozzle 22) has a significant incidence at its point of impact on the reflection surface 34. Here we call "incidence" the angle A between the axis of the nozzle and the generator of the reflection surface, at the point of impact. This incidence will preferably be between 30 and 60 °. The half-angle at the top of the frustoconical surface 34 will be between 15 and 75 ° and preferably between 30 and 60 °. In the example shown, the incidence A and the half-angle at the top of the frustoconical surface 34 are close to 45 °.

La vitesse de débit du jet de liquide de nettoyage, c'est-à-dire le rapport entre le débit du liquide et la section de l'ajutage d'éjection de la buse 22, est comprise entre 15 et 50 m/s. De façon classique, la vitesse de rotation de l'organe tournant peut être choisie dans des limites assez grandes, entre 6000 et 60000 tour/min. Elle sera de préférence supérieure à 20000 tour/min.The speed of flow of the jet of cleaning liquid, that is to say the ratio between the flow of the liquid and the section of the nozzle for ejection of the nozzle 22, is between 15 and 50 m / s. Conventionally, the speed of rotation of the rotary member can be chosen within fairly large limits, between 6000 and 60000 rpm. It will preferably be greater than 20,000 rpm.

Le fonctionnement du dispositif qui vient d'être décrit est le suivant.The operation of the device which has just been described is as follows.

En phase de projection, le produit de revêtement est éjecté avec une certaine vitesse choisie de la buse 20 et rencontre la face 16a du voile 16. Comme expliqué ci-dessus, sous l'effet de la force centrifuge, il s'achemine vers le bord de pulvérisation 28 en traversant les trous 24 à la périphérie du voile 16.Projection phase, the coating material is ejected with a velocity selected in the nozzle 20 and encounters the face 16 a of the web 16. As explained above, under the effect of centrifugal force, it is moving towards the spray edge 28 passing through the holes 24 at the periphery of the web 16.

Lorsqu'on désire nettoyer l'organe tournant 12, l'alimentation de produit de revêtement est coupée et du produit de nettoyage est éjecté avec une certaine vitesse choisie par la buse 22 en direction du voile 16. Le jet de liquide de nettoyage, lorsqu'il n'est pas intercepté par les parois latérales des trous 32 ou la face 16a entre ces trous, vient frapper la surface de réflexion 34 et on observe une répartition du liquide de nettoyage à la fois sur la partie conique 37 du moyeu et, plus généralement, sur toutes les zones du voile 16. Du liquide de nettoyage traverse également les trous 24. La totalité du liquide de nettoyage finit par s'écouler le long de la paroi tronconique 26 jusqu'au bord d'éjection 28.When it is desired to clean the rotating member 12, the coating product supply is cut off and the cleaning product is ejected with a certain speed chosen by the nozzle 22 in the direction of the web 16. The jet of cleaning liquid, when it is not intercepted by the side walls of the holes 32 or the face 16 a between these holes , strikes the reflecting surface 34 and a distribution of the cleaning liquid is observed both on the conical part 37 of the hub and, more generally, on all the areas of the web 16. Cleaning liquid also passes through the holes 24. All of the cleaning liquid ends up flowing along the frustoconical wall 26 to the ejection edge 28.

On peut supposer que le liquide de nettoyage qui vient frapper la surface de réflexion 36 se divise en plusieurs fractions. Une première fraction, peu mise en rotation, est réfléchie par la surface 34 et dirigée vers la partie terminale 37 du moyeu. Le liquide de nettoyage venant ainsi frapper la partie centrale du voile s'écoulerait ensuite sous l'effet de la force centrifuge le long de l'extrémité conique 37 avant d'être éjecté radialement vers l'extérieur, dans l'épaisseur du voile. Une autre fraction, également peu mise en rotation, s'écoule en direction de l'orifice 36 sous l'action de sa force vive d'éjection par la buse 22. Cette partie s'écoule ensuite le long de la face frontale du voile 16 puis, le long de la surface tronconique 26. Enfin, une troisième fraction mise en rotation s'écoule dans l'épaisseur du voile dans la direction de plus grand diamètre sous l'action de la composante axiale de la force centrifuge. Cette fraction traverse donc les trous 32 vers l'arrière et s'écoule radialement le long de la face 16a du voile 16 avant de passer par les trous 24 en direction du bord de pulvérisation 28. Ainsi, toutes les parties du bol reçoivent du liquide de nettoyage, notamment la totalité de la face avant du voile.It can be assumed that the cleaning liquid which strikes the reflecting surface 36 is divided into several fractions. A first fraction, little rotated, is reflected by the surface 34 and directed towards the end portion 37 of the hub. The cleaning liquid thus striking the central part of the veil would then flow under the effect of centrifugal force along the conical end 37 before being ejected radially outwards, in the thickness of the veil. Another fraction, also little rotated, flows in the direction of the orifice 36 under the action of its strong force of ejection by the nozzle 22. This part then flows along the front face of the web 16 then, along the frustoconical surface 26. Finally, a third fraction rotated flows in the thickness of the web in the direction of larger diameter under the action of the axial component of the centrifugal force. This fraction thus passes through the holes 32 rearwardly and radially flows along the face 16a of the web 16 before passing through the holes 24 towards the spraying edge 28. Thus, all parts of the bowl receive cleaning liquid, in particular the entire front face of the veil.

Claims (12)

  1. A centrifugal atomisation device for atomising a coating product, of the type comprising a generally bowl-shaped rotating member (12) provided with an internal disc (16) extending substantially perpendicularly to the axis of rotation of said rotating member between a drive hub (15) and the internal surface (26) of said bowl, said disc defining in the interior of said bowl a front cavity (17) which is open in the spraying direction and a rear cavity (18) which encloses said hub, in which device a coating product ejection nozzle (20) and a cleaning product ejection nozzle (22) are accommodated in said rear cavity and are both directed towards said disc, and passages (24) are provided at the outside periphery of said disc in the vicinity of said internal surface (26), characterised in that said disc comprises an annular opening (30) which communicates with said rear cavity (18) and in which there is defined a reflection surface (34) for returning a part of a jet of liquid towards the central part of said disc, and that said cleaning product ejection nozzle (22) is oriented towards said reflection surface (34).
  2. A device according to claim 1 characterised in that said reflection surface (34) is a generally concave surface having its concavity directed towards said rear cavity (18) and its central zone opening into said front cavity (17).
  3. A device according to claim 2 characterised in that said generally concave surface (34) is substantially frustoconical.
  4. A device according to one of the preceding claims characterised in that said annular opening communicates with said rear cavity by way of regularly circumferentially spaced holes (32).
  5. A device according to claim 4 characterised in that said holes (32) are frustoconical, their larger-diameter orifices opening into said rear cavity (18).
  6. A device according to one of the preceding claims characterised in that said hub (15) is frustoconical, the diameter thereof increasing from the rear forwardly.
  7. A device according to one of the preceding claims characterised in that the axis of the cleaning liquid ejection nozzle is substantially parallel to the axis of rotation (x'x) of said rotating member.
  8. A device according to one of the preceding claims characterised in that the angle of incidence (A) between the axis of ejection of the cleaning liquid and said reflection surface is between 30 and 60°.
  9. A device according to one of claims 3 to 8 characterised in that the half-angle at the apex of the frustoconical reflection surface (34) is between 15 and 75°, preferably between 30 and 60°.
  10. A device according to one of claims 3 to 9 characterised in that the angle of incidence (A) between the axis of ejection of said cleaning product ejection nozzle and the generatrix of the reflection surface at the point of impact and the half-angle at the apex of the frustonical reflection surface (34) are close to 45°.
  11. A device according to one of the preceding claims characterised in that the flow rate of the jet of cleaning liquid is between 15 and 50 m/s.
  12. A device according to one of the preceding claims characterised in that the speed of rotation of said rotating member is between 6000 revolutions per minute and 60,000 revolutions per minute, preferably greater than 20,000 revolutions per minute.
EP91401044A 1990-04-24 1991-04-19 Device for centrifugally spraying a coating material, more particularly for electrostatic spray coating Expired - Lifetime EP0454548B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9005203 1990-04-24
FR9005203A FR2661115B1 (en) 1990-04-24 1990-04-24 DEVICE FOR CENTRIFUGAL SPRAYING OF A COATING PRODUCT, ESPECIALLY FOR APPLICATION BY ELECTROSTATIC SPRAYING.

Publications (2)

Publication Number Publication Date
EP0454548A1 EP0454548A1 (en) 1991-10-30
EP0454548B1 true EP0454548B1 (en) 1993-10-13

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EP91401044A Expired - Lifetime EP0454548B1 (en) 1990-04-24 1991-04-19 Device for centrifugally spraying a coating material, more particularly for electrostatic spray coating

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US (1) US5137215A (en)
EP (1) EP0454548B1 (en)
JP (1) JPH04227874A (en)
DE (1) DE69100498T2 (en)
ES (1) ES2046868T3 (en)
FR (1) FR2661115B1 (en)

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US5433387A (en) * 1992-12-03 1995-07-18 Ransburg Corporation Nonincendive rotary atomizer
US5633306A (en) * 1992-12-03 1997-05-27 Ransburg Corporation Nonincendive rotary atomizer
DE4306799A1 (en) * 1993-03-04 1994-09-08 Duerr Gmbh & Co Rotary sprayer for a coating apparatus
DE9419641U1 (en) * 1994-12-07 1995-02-02 Duerr Gmbh & Co Rotary atomizer with a bell body
JP2809170B2 (en) * 1996-01-19 1998-10-08 トヨタ自動車株式会社 Rotary atomizing electrostatic coating equipment
US5957395A (en) * 1997-10-21 1999-09-28 Illinois Tool Works Inc. Safe charging
US6042030A (en) * 1998-03-23 2000-03-28 Howe; Varce E. Safe charging with non-insulative atomizer
US6322011B1 (en) * 2000-03-14 2001-11-27 Illinois Tool Works Inc. Electrostatic coating system and dual lip bell cup therefor
DE10342188A1 (en) * 2003-02-27 2004-09-16 Dürr Systems GmbH Bell plate and rotary atomizer
US20050040257A1 (en) * 2003-08-19 2005-02-24 Seitz David M. Atomizer with dedicated cleaning fluid system
US8602326B2 (en) * 2007-07-03 2013-12-10 David M. Seitz Spray device having a parabolic flow surface
DE102014019309A1 (en) * 2014-12-20 2016-06-23 Eisenmann Se Nozzle head and rotary atomizer with such
CN112657697A (en) * 2020-12-15 2021-04-16 安徽新和博亚电子科技有限公司 Electrostatic powder spraying equipment for surface of electronic component and spraying method thereof

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JPS5787863A (en) * 1980-11-19 1982-06-01 Toyota Motor Corp Spraying head of rotary atomizing electrostatic coating device
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Also Published As

Publication number Publication date
EP0454548A1 (en) 1991-10-30
US5137215A (en) 1992-08-11
DE69100498D1 (en) 1993-11-18
JPH04227874A (en) 1992-08-17
FR2661115B1 (en) 1992-07-31
ES2046868T3 (en) 1994-02-01
FR2661115A1 (en) 1991-10-25
DE69100498T2 (en) 1994-03-17

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