EP1461160B1 - Dispositif pour une peinture electrostatique de bandes metalliques presentant une efficacite de depot amelioree - Google Patents

Dispositif pour une peinture electrostatique de bandes metalliques presentant une efficacite de depot amelioree Download PDF

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Publication number
EP1461160B1
EP1461160B1 EP02703540A EP02703540A EP1461160B1 EP 1461160 B1 EP1461160 B1 EP 1461160B1 EP 02703540 A EP02703540 A EP 02703540A EP 02703540 A EP02703540 A EP 02703540A EP 1461160 B1 EP1461160 B1 EP 1461160B1
Authority
EP
European Patent Office
Prior art keywords
accordance
strip
powder
suction
planes
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
EP02703540A
Other languages
German (de)
English (en)
Other versions
EP1461160A1 (fr
Inventor
Giovanni Bortolato
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.)
Lasa Impianti Srl
Original Assignee
Lasa Impianti Srl
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Lasa Impianti Srl filed Critical Lasa Impianti Srl
Publication of EP1461160A1 publication Critical patent/EP1461160A1/fr
Application granted granted Critical
Publication of EP1461160B1 publication Critical patent/EP1461160B1/fr
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
    • B05B5/08—Plant for applying liquids or other fluent materials to objects
    • B05B5/14—Plant for applying liquids or other fluent materials to objects specially adapted for coating continuously moving elongated bodies, e.g. wires, strips, pipes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B14/00—Arrangements for collecting, re-using or eliminating excess spraying material
    • B05B14/10—Arrangements for collecting, re-using or eliminating excess spraying material the excess material being particulate
    • 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
    • B05B5/03—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying
    • B05B5/032—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying for spraying particulate materials

Definitions

  • the present invention relates to a device for exposing a metallic strip to electrostatic painting and suction of the excess powder projected and enabling increased production velocity and finish quality.
  • Such an electrostatic painting device is known from DE 7 532 679 U.
  • the powder is taken to each gun through a delivery tube connected to a venturi pump fed with compressed air by means of an adjustable pressure reducing valve with pressure readable on a pressure gauge.
  • the pumps suck proportionately to the supplied air pressure a certain quantity of powder to be sent to the guns through a tube drawing in a tank of fluidised powder.
  • each gun must be set individually by regulating the air pressure of its venturi pump and additional compressed air termed 'dilution air'. It is clear that to increase the painted surface area in the time unit we must increase the number of electrostatic guns or increase the flow of powder to the guns in the time unit.
  • Deposit on the strip surface of the electrostatically charged powder is subject basically to two types of forces, to wit:
  • the amount of charge absorbed by the powder particles decisively influences deposit on the strip surface.
  • the powder is charged by the corona effect (known physical effect of emission of electrons from an electrode connected to a high voltage generator which in attaching to the surrounding air molecules makes them, from neutral, electrically charged negative charges and in turn they adhere to particular zones of the surface of the powder grains known as electronegative affinity).
  • the amount of charge imparted to the powder depends on several parameters, to wit:
  • the increase in the electrode current under specific conditions allows charging a larger quantity of powder emitted thus approaching the 60% theoretical deposit.
  • the positioning and suction device which is the object of the present invention also achieves the following purposes:
  • figure 1 shows the normal positioning of the metallic strip (1) stretched by the tension rollers (2) and (3) with the electrostatic guns (4) in painting position perpendicular to the surface.
  • Figure 2 shows diagrammatically the field intensity near the strip surface with the darker segment (8) occupying a portion of the strip surface approximately equal to that of the powder emission cone from the gun.
  • the trend of projection of the powder (9) is characterized by zones (10) where the rebound of the particles thereof projected towards the surface causes rotary motion thereof, which is accelerated on the edges of the strip because of the air suction of the hood (11) to recover the powder particles which were not deposited. Because of the powder friction effect this acceleration can cause considerable thickness differences on the strip edges due to erosion as explained above.
  • the very intense electrical field on the strip surface in the powder deposit zone has the described effect of having a repulsion force towards the powder particles which are to be deposited on the surface.
  • This force tends to accelerate the powder with a direction contrary to that of their aerodynamic velocity directed towards the exposed surface. Therefore the powder particles tend to slow down their deposit velocity.
  • This slowing has the effect that near the surface there is a dense layer of accumulated particles in balance between the various forces, viz electrostatic and aerodynamic, which prevents further deposit of the powder.
  • Figure 4 shows graphically what happens with the repulsion effects due to the electrical fields and particle charges.
  • the deposited particles (12) represent a surface charge with associated electrical field (13) represented by the arrows which repel the new powder particles (14) represented as thickened with respect to the particles (15) emitted near the gun since they are slowed by the field (13). It is clear that as the air and powder mixture emitted becomes denser this phenomenon is accentuated.
  • the system invented allows diminishing the effect of the gun electrical fields, cancelling the effects due to powder emission velocity and hence cancellation of the erosion effects and allowing greater production velocity.
  • the invention consists of a tension means or roller (22) placed in any position between the rollers normally used (2) and (3) so as to form a more or less acute angle and the two suction means or hoods (16) and (17) positioned so as to suck air only in parallel and not laterally with respect to the two new running planes of the strip (19) and (18).
  • the paint guns are positioned at the height of the corner (20) formed by the two planes (19) and (18).
  • the particles deposited along the plane (18) must have an electrical charge such as to allow adhesion to the surface and overcome both the suction force of the hood (17) and the force of gravity which tends to detach them. It is clear that the layer of powder deposited on this plane is made up only of particles having an excellent electrical charge with those having an insufficient charge to overcome the forces of suction and gravity being eliminated.
  • This type of coating made up of particles with strong adhesion ensures a surface with excellent spreading and visual finish once it is polymerized in the baking oven as known.
  • the suction hood (16) is shifted into a position closer to the corner (20) and this is done in such a manner that its suction velocity is greater than that of the hood (17) so as to make up for the force of gravity effect which would oblige the uncharged particles to fall back on the strip.
  • the powder emission is divided mechanically along the two running planes.
  • deflectors can be provided.
  • Known shifting means in painting system (4) enable distribution of the painting powder on the two planes in a chosen manner by shifting the painting system upward or downward relative to the corner.
  • the present invention enables:
  • the device in accordance with the present invention is easy and economical to construct despite the considerable advantages which it brings to the industrial process of electrostatic painting of metallic strips.

Claims (17)

  1. Dispositif pour la peinture de bandes métalliques (1) en utilisant une poudre électrostatique, comprenant un système de peinture émettant la poudre vers la bande (1), caractérisé par un moyen de tension de la bande (22) positionné de manière à former autour de lui un angle plus ou moins aigu avec la bande (1); deux moyens d'aspiration (16, 17) situés le long des plans de la bande sortant dudit angle, les moyens d'aspiration (16, 17) ayant une aspiration parallèle auxdits plans et le système de peinture (4) effectuant des émissions perpendiculaires audit angle formé par lesdits plans.
  2. Dispositif selon la revendication 1, caractérisé par le moyen de tension (22) comportant un rouleau.
  3. Dispositif selon la revendication 1, caractérisé par les moyens d'aspiration (16, 17) se composant d'une hotte d'aspiration.
  4. Dispositif selon la revendication 3, caractérisé par une aspiration d'air effectuée par les deux hottes parallèles aux deux plans dans lesquels la bande (1) est divisée autour du moyen de tension (22).
  5. Dispositif selon la revendication 1, caractérisé par les deux moyens d'aspiration (16, 17) ayant des écoulements d'aspiration différents.
  6. Dispositif selon la revendication 1, caractérisé en ce qu'un moyen d'aspiration est situé à une distance plus petite que l'autre moyen, à partir du coin formé par ledit angle.
  7. Dispositif selon la revendication 1, caractérisé en ce qu'un desdits plans de la bande se trouve au-dessus de l'autre plan de la bande.
  8. Dispositif selon la revendication 7, caractérisé en ce que les moyens d'aspiration (16, 17) correspondant audit un plan de la bande ont une vitesse d'aspiration supérieure à la vitesse d'aspiration des moyens d'aspiration correspondant à l'autre plan de la bande.
  9. Dispositif selon la revendication 7, caractérisé en ce que les moyens d'aspiration (16, 17) correspondant audit un plan de la bande sont situés à une distance plus petite que les moyens correspondant à l'autre plan, à partir du coin formé par ledit angle.
  10. Dispositif selon la revendication 1, caractérisé par la mise en place du système de peinture (4) en position perpendiculaire au coin formé par ledit angle.
  11. Dispositif selon la revendication 1, caractérisé en ce que l'émission de poudre est divisée mécaniquement le long de deux plans de roulement.
  12. Dispositif selon la revendication 1, caractérisé en ce qu'il permet la dilution de la poudre émise par un système d'aspiration extérieur.
  13. Dispositif selon la revendication 1, caractérisé par la dilution de la poudre divisant son écoulement le long de deux surfaces indépendantes.
  14. Dispositif selon la revendication 1, caractérisé par une diminution des champs électriques par leur fermeture sur une partie saillante tel que le coin formé par ledit angle.
  15. Dispositif selon la revendication 1, caractérisé par la distribution de la poudre de peinture sur les deux plans d'une façon sélectionnée par des moyens de déplacement qui déplacent le système de peinture (4) vers le haut ou vers le bas par rapport au coin.
  16. Dispositif selon la revendication 1, caractérisé en ce que le moyen de tension (22) forme une courbe autour de lui pour une bande métallique.
  17. Dispositif selon la revendication 1, caractérisé par au moins deux hottes d'aspiration.
EP02703540A 2002-01-02 2002-01-02 Dispositif pour une peinture electrostatique de bandes metalliques presentant une efficacite de depot amelioree Expired - Lifetime EP1461160B1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2002/000116 WO2003055609A1 (fr) 2002-01-02 2002-01-02 Dispositif pour une peinture electrostatique de bandes metalliques presentant une efficacite de depot amelioree

Publications (2)

Publication Number Publication Date
EP1461160A1 EP1461160A1 (fr) 2004-09-29
EP1461160B1 true EP1461160B1 (fr) 2005-03-16

Family

ID=8164770

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02703540A Expired - Lifetime EP1461160B1 (fr) 2002-01-02 2002-01-02 Dispositif pour une peinture electrostatique de bandes metalliques presentant une efficacite de depot amelioree

Country Status (6)

Country Link
EP (1) EP1461160B1 (fr)
AT (1) ATE290930T1 (fr)
AU (1) AU2002237262A1 (fr)
DE (1) DE60203326D1 (fr)
ES (1) ES2236484T3 (fr)
WO (1) WO2003055609A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7626602B2 (en) 2006-09-15 2009-12-01 Mcshane Robert J Apparatus for electrostatic coating
GB0911260D0 (en) * 2009-06-30 2009-08-12 British American Tobacco Co Applicator

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE7532679U (de) * 1977-05-05 Roeth + Co, 6700 Ludwigshafen Vorrichtung zum elektrostatischen Besprühen eines flächigen Gegenstandes, insbesondere einer laufenden Papierbahn
DE7215571U (de) * 1974-04-18 Voith J Gmbh Vorrichtung zum Auftragen von flüssigen oder pulverförmigen Mitteln auf eine laufende Papierbahn
GB1072951A (en) * 1964-03-23 1967-06-21 Gevaert Photo Prod Nv Method and apparatus for coating liquid compositions onto webs of paper and other material
US4826703A (en) * 1987-06-01 1989-05-02 Polaroid Corporation Method and apparatus for electrically controlling coating layer dimensions
EP0470712B1 (fr) * 1990-08-09 1995-12-13 Imperial Chemical Industries Plc Pulvérisation des liquides
US6040004A (en) * 1995-03-09 2000-03-21 3M Innovative Properties Company Method and apparatus for fabricating a particle-coated substrate, and such substrate

Also Published As

Publication number Publication date
DE60203326D1 (de) 2005-04-21
EP1461160A1 (fr) 2004-09-29
ES2236484T3 (es) 2005-07-16
AU2002237262A1 (en) 2003-07-15
WO2003055609A1 (fr) 2003-07-10
ATE290930T1 (de) 2005-04-15

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