EP0498155A1 - Dispositif pour la pulvérisation de poudres chargées électrostatiquement sur des objets - Google Patents

Dispositif pour la pulvérisation de poudres chargées électrostatiquement sur des objets Download PDF

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Publication number
EP0498155A1
EP0498155A1 EP92100232A EP92100232A EP0498155A1 EP 0498155 A1 EP0498155 A1 EP 0498155A1 EP 92100232 A EP92100232 A EP 92100232A EP 92100232 A EP92100232 A EP 92100232A EP 0498155 A1 EP0498155 A1 EP 0498155A1
Authority
EP
European Patent Office
Prior art keywords
powder
interspace
spray
electrostatically charged
coating
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.)
Withdrawn
Application number
EP92100232A
Other languages
German (de)
English (en)
Inventor
Sergio Cocchi
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.)
ITEP SpA
Original Assignee
ITEP SpA
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 ITEP SpA filed Critical ITEP SpA
Publication of EP0498155A1 publication Critical patent/EP0498155A1/fr
Withdrawn legal-status Critical Current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
    • B05B5/03—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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B16/00—Spray booths
    • B05B16/90—Spray booths comprising conveying means for moving objects or other work to be sprayed in and out of the booth, e.g. through the booth
    • B05B16/95—Spray booths comprising conveying means for moving objects or other work to be sprayed in and out of the booth, e.g. through the booth the objects or other work to be sprayed lying on, or being held above the conveying means, i.e. not hanging from the conveying means
    • 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

Definitions

  • the present invention relates to a device for applying electrostatically charged powders for the spray-coating of objects.
  • the powder contained in a feeder is drawn by pumps, usually of the Venturi-tube type operated by compressed air, and is sent to the guns by means of flexible plastic tubes.
  • the guns expel the powder onto the items, simultaneously charging the particles with an electrostatic field generated by one or more high-voltage electrodes (30-100 kV) located in the terminal portion of the gun or inside it.
  • the items are generally suspended from an overhead conveyor and enter a containment chamber, or booth, where the application process occurs; the booth is kept at a negative pressure by an aspiration system so that dangerous concentrations are not reached.
  • Said overspray furthermore remains in suspension in the spray booth, with the problem that it deposits on the walls or on devices such as guns, robot arms etc., and occasionally on items which must then be rejected, at the quality control.
  • the items which must be coated only on one side, are placed on the conveyor belt and, inside the booth, are located below the guns instead of laterally thereto, so that the powder deposited on the guns, nozzles and any robot arms falls onto said items.
  • the aim of the present invention is to overcome the disadvantages of the known art by providing a device for applying products in powder form which prevents said powder from accumulating on the gun body.
  • an object of the invention is to provide a device which is simple from the constructive point of view and can be adapted to the various types of gun.
  • a device for applying electrostatically charged powders for the spray-coating of objects comprising at least one first tubular body which has a first end for the inflow of the powder and a second end for the outflow of the electrostatically charged powder, characterized in that it comprises a second tubular body which is porous to air and contains said first tubular body, an interspace being defined between said first body, and said second body, said interspace being kept at a pressure higher than the ambient pressure in order to prevent said powder from depositing on the outer surface of said second body.
  • the device according to the invention comprises a first body 3 which, in the case illustrated in Figure 1, constitutes the actual electrostatic gun and substantially comprises a nozzle, provided with ionization electrodes 5, from which the electrostatically charged powder escapes in a per se known manner.
  • the gun 3 is normally at least partially contained within a booth 7; the conveyor belt 9, on which the item 11 to be sprayed is arranged, advances inside said booth. In the case illustrated in Figure 1, the gun 3 partially protrudes outside the booth through the opening 13.
  • the first body 3 is contained in a second tubular body 15 which is made of a material which is porous with regard to air and has a lower base which is open at the nozzle and at the electrodes 5 in order to allow the powder to escape.
  • the upper base 21 of the second body 15 is instead located outside the booth 7 and closes around the first body 3; an inflow duct 17 is connected to the second body 15 at the upper base and is suitable for feeding compressed air to the interspace 19 defined between the first body 3 and the second body 15.
  • the inflow duct 17 is advantageously connected to adapted electric valves so as to feed compressed air to the interspace 19, in a continuous or programmed manner, until the internal pressure reaches such a value as to exceed the resistance of the porous walls of the body 15, so as to create a uniform air current, indicated by the arrows in the drawings, which prevents the powder from clinging to the entire outer surface of the body 15.
  • Figure 2 is a view of a device 101 which is fully similar to the preceding one, except for the fact that the first body 3, which corresponds to the actual electrostatic gun in this case as well, is completely inside the booth 7 and is connected to an extension support or duct 103 which protrudes from the opening 13 of the booth.
  • the upper base 21 of the second body 15 closes around the support 103 but is in any case outside the booth 7.
  • device 101 is necessary when, for example, the length of the gun body is not sufficient to allow the unit to protrude outside the booth.
  • Figure 3 is a view of another embodiment of the invention, wherein the device 201 substantially comprises a gun body 3 which is external to the booth 7 and is connected to a first body constituted by an extension 203. Accordingly, the second body 15 contains the extension 203 but, in a manner fully similar to what has been described above, the upper base is in any case located outside the booth 7 and is located at the connection to the gun body.
  • Figures 4 and 5 are views of a device 301 according to another aspect of the invention, wherein the second body 15 contains the first body 3, constituted by the actual gun; the device 301 can in any case be executed by means of guns of the types shown in Figures 2 and 3.
  • the device 301 comprises a lower base 203 which has an annular chamber 25 connected to the outside by means of small holes 27 directed toward the nozzle and the electrodes 5.
  • the invention achieves the intended aim and objects by providing a completely self-cleaning device which can prevent the powder from depositing on the gun body.
  • the materials employed, as well as the dimensions, may naturally be any according to the requirements and to the state of the art.

Landscapes

  • Electrostatic Spraying Apparatus (AREA)
EP92100232A 1991-02-06 1992-01-09 Dispositif pour la pulvérisation de poudres chargées électrostatiquement sur des objets Withdrawn EP0498155A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI910289A IT1247838B (it) 1991-02-06 1991-02-06 Dispositivo per l'applicazione di polveri elettrostaticamente caricate per il rivestimento a spruzzo di oggetti
ITMI910289 1991-02-06

Publications (1)

Publication Number Publication Date
EP0498155A1 true EP0498155A1 (fr) 1992-08-12

Family

ID=11358432

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92100232A Withdrawn EP0498155A1 (fr) 1991-02-06 1992-01-09 Dispositif pour la pulvérisation de poudres chargées électrostatiquement sur des objets

Country Status (2)

Country Link
EP (1) EP0498155A1 (fr)
IT (1) IT1247838B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4414513A1 (de) * 1993-04-27 1994-11-03 Itw Ltd Elektrostatisches System
EP1170060A1 (fr) 2000-06-23 2002-01-09 FRoSTA Aktiengesellschaft Procédé de pulvérisation électrostatique de liquide et de produit sec sur des produits alimentaires au moyen de buses de pulvérisation

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54118446A (en) * 1978-03-07 1979-09-13 Kansai Paint Co Ltd Powder spraying gun
FR2421683A1 (fr) * 1978-04-06 1979-11-02 Ransburg Sa Support de tete atomisante
JPS55152564A (en) * 1979-05-14 1980-11-27 Kansai Paint Co Ltd Electrostatic powder spray gun with powder deposition preventer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54118446A (en) * 1978-03-07 1979-09-13 Kansai Paint Co Ltd Powder spraying gun
FR2421683A1 (fr) * 1978-04-06 1979-11-02 Ransburg Sa Support de tete atomisante
JPS55152564A (en) * 1979-05-14 1980-11-27 Kansai Paint Co Ltd Electrostatic powder spray gun with powder deposition preventer

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 3, no. 138 (C-64)16 November 1979 & JP-A-54 118 446 ( KANSAI PAINT CO. LTD. ) 13 September 1979 *
PATENT ABSTRACTS OF JAPAN vol. 5, no. 28 (C-44)20 February 1981 & JP-A-55 152 564 ( KANSAI PAINT CO. LTD. ) 27 November 1980 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4414513A1 (de) * 1993-04-27 1994-11-03 Itw Ltd Elektrostatisches System
EP1170060A1 (fr) 2000-06-23 2002-01-09 FRoSTA Aktiengesellschaft Procédé de pulvérisation électrostatique de liquide et de produit sec sur des produits alimentaires au moyen de buses de pulvérisation

Also Published As

Publication number Publication date
ITMI910289A1 (it) 1992-08-06
IT1247838B (it) 1995-01-02
ITMI910289A0 (it) 1991-02-06

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