US3764068A - Method of protecting electrostatic spray nozzles from fouling - Google Patents

Method of protecting electrostatic spray nozzles from fouling Download PDF

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Publication number
US3764068A
US3764068A US00266398A US3764068DA US3764068A US 3764068 A US3764068 A US 3764068A US 00266398 A US00266398 A US 00266398A US 3764068D A US3764068D A US 3764068DA US 3764068 A US3764068 A US 3764068A
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US
United States
Prior art keywords
liquid
product
nozzle
auxiliary
needles
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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US00266398A
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English (en)
Inventor
A Lacchia
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Air Industrie SA
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Air Industrie SA
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Publication date
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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
    • B05B5/03—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying
    • 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

  • ABSTRACT A method of protection of electrostatic projection nozzles against fouling due to the rebounding of a small proportion of the projected ionized particles from the object to be coated with a liquid-coating product comprises essentially the provision of an auxiliary liquid product in addition to the main liquid coating product, the auxiliary liquid being electrically charged to a high voltage of the same sign as the charge of the liquid coating product, and being projected simultaneously with the liquid-coating product towards the front of the projection nozzle and from at least one point external to the central portion of said nozzle so as to oppose and annul the opposite charge on the rebounding particles.
  • the nozzle is provided on its periphery with a plurality of needles formed by fine, hollow tubes with bevelled free extremities which are charged to the electric potential of the same sign as that of the projection nozzle.
  • the present invention relates to a method and an apparatus intended to prevent fouling of projection nozzles of electrostatic projection apparatus for liquid coating products.
  • Electrostatic projection nozzles are generally brought up to a high electric potential and are supplied with the coating product, generally together with spraying air. These nozzles may be mounted on all types of installations, both fixed and manual.
  • the particles of coating product are charged, in a manner known per se, at the level of the projection nozzle, and are then projected in the direction of the object to be coated, in the electric field created between the projection apparatus and the said object which is generally earthed.
  • the present invention makes it possible to avoid these disadvantages and to ensure the correct operation of an installation for the electrostatic projection of a product for at least several hours under the most unfavorable conditions.
  • the invention consists of a method according to which there is projected, from a point external to the central portion of the projection nozzle, in a direction opposite to that of the return particles, an auxiliary jet of a charged liquid product.
  • the invention also relates to an apparatus for carrying this method into effect, characterized in that the periphery of a projection nozzle is provided with hollow and fine needles, the extremity of which may be bevelled if so required, of the kind employed as medical needles, these needles being brought up to the high-tension voltage, and in that an auxiliary chosen liquid product is projected through the said needles in a continuous or intermittent manner.
  • the return particles are repelled mechanically by means of the jet of auxiliary product, after having trapped these particles in the vicinity of the needles by means of the high electric field created by the said needles;
  • FIG. 1 shows diagrammatically a view in longitudinal cross-section of an electrostatic projection nozzle for a liquid product according to the invention
  • FIG. 2 shows diagrammatically a view in transverse section of the same projection nozzle
  • FlG.3 shows diagrammatically a front view in partial cross-section of the same projection nozzle, showing the supply system for the auxiliary product;
  • FIGA shows diagrammatically a view looking on the top of the nozzle according to the invention.
  • the electrostatic projection nozzle comprises anozzle body 1, a diffuser 2, an insulating cap 3 and an external nut 4.
  • the liquid coating product is introduced at 5 into the diffuser 2 and passes out through the product outlet 6.
  • the spraying air is introduced into the nozzle through the conduits 7 and then, after passing into the vortex chamber, passes out as a turbulent jet of liquid spray through the annular orifice 8.
  • the parts 1 and 2 are of metal and are brought up to a high voltage, an electric field being thus created between the nozzle and the object.
  • a metal memher 4 replacing the usual external nut and comprising as shown fine hollow needles 9 with a bevelled extremity of the medical needle" type, located on the outer periphery of the nozzle 8 and directed towards the object to be coated.
  • the part 4 further comprises chambers 10 and 11 for the formation of an auxiliary airproduct mixture, together with an inlet for a device permitting the ejection into the chamber 10 of a mixture of gases, generally of air and finely pulverized auxiliary product.
  • the member 4 and in consequence the needles 9 are brought-up to a high voltage.
  • the liquid coating product is atomized, charged electrically and projected in the direction of the object, at the level of the openings 6 and 8.
  • an auxiliary liquid compatible with the coating liquid such as water in the case of enamel, or a solvent in the case of paint.
  • the inlet element 13 comprises a central intake conduit 14 for the auxiliary liquid, and an annular intake conduit 15 for compressed air, surrounding the conduit 14, together with a convergent-divergent system which enables the mixture to be effected.
  • the said mixture of air and auxiliary liquid carried out in the element 13 is brought tangentially into the chamber 10 in which it thereby acquires a slight whirling movement which permits a first improvement in the uniformity of the auxiliary air-liquid mixture.
  • the chamber 10 communicates with a second chamber 11 by conduits 16 formed tangentially in the same direction as the element 13, in order to obtain in the said chamber 11 a perfect vortex effect which ensures good uniformity of the auxiliary air-liquid mixture at the base of each needle 9.
  • This mixture is ejected through the hollow needles 9 with bevelled extremities.
  • the drops of auxiliary product are charged electrically by the sharpened extremities of the needles 9 brought up to a high tension, and thus form a cloud of electrified liquid particles surrounding the main jet from the nozzle and tending to oppose, following the process previously explained, the return after rebounding on the object, 1 of particles charged with the opposite sign to the particles emitted by the nozzle and the needles.
  • the humidity of the auxiliary air-liquid mixture enables a continuous cleaning of the needles 9 to be ensured.
  • the invention is obviously not limited to the arrangement described, and it is for example possible to imagine the supply of the needles 9 with an auxiliary liquid unmixed with a gas. Furthermore, it is also not essential that the projection device for the charged auxiliary product according to the invention, should form part of the body of the nozzle, and an absolutely independent construction of this latter may perfectly well be employed.
  • the invention may be utilized in all electrostatic projection installations for liquid products, used in particular in the enamelling and painting industry for metallic or ceramic parts, and also in the paper-making industry, in particular for the glueing and surface treatment of paper.
  • a method of protection against fouling of the nozzles of electrostatic projection apparatus for liquidcoating products comprising essentially the steps of: providing an auxiliary liquid product in addition to said liquid-coating product; projecting said auxiliary liquid simultaneously with said liquid-coating product; electrically charging said auxiliary liquid product to a high voltage; and projecting said auxiliary product towards the front of the projection nozzle and from at least one location external to the central portion of said projection nozzle.
  • auxiliary liquid product is a product compatible with the main lqiudi-coating product projected by said nozzle.
  • An electrostatic projection nozzle for a liquidcoating product adapted to carry into effect the method as claimed in claim 1, in which said nozzle is provided, on its periperhy, with a plurality of needles constituted by fine and hollow tubes, the extremities of said needles being brought up to an electric potential of the same sign as the electrical high-tension voltage of said projection nozzle.
  • An electrostatic projection nozzle as claimed in claim 6, said nozzle comprising a device for the formation and the injection of an auxiliary gas-liquid mixture into said needles.

Landscapes

  • Electrostatic Spraying Apparatus (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Details Or Accessories Of Spraying Plant Or Apparatus (AREA)
  • Nozzles (AREA)
US00266398A 1971-08-02 1972-06-26 Method of protecting electrostatic spray nozzles from fouling Expired - Lifetime US3764068A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7128515A FR2158582A5 (de) 1971-08-02 1971-08-02

Publications (1)

Publication Number Publication Date
US3764068A true US3764068A (en) 1973-10-09

Family

ID=9081424

Family Applications (1)

Application Number Title Priority Date Filing Date
US00266398A Expired - Lifetime US3764068A (en) 1971-08-02 1972-06-26 Method of protecting electrostatic spray nozzles from fouling

Country Status (6)

Country Link
US (1) US3764068A (de)
JP (1) JPS511252B2 (de)
DE (1) DE2234026C3 (de)
FR (1) FR2158582A5 (de)
GB (1) GB1377148A (de)
IT (1) IT962639B (de)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3896994A (en) * 1972-03-23 1975-07-29 Walberg Arvid C & Co Electrostatic deposition coating system
US3938740A (en) * 1973-10-04 1976-02-17 Atlas Copco Aktiebolag Nozzle for electrostatic spray gun
US3951340A (en) * 1972-11-27 1976-04-20 Air-Industrie Electrostatic powder projection system and method
US3952951A (en) * 1974-03-13 1976-04-27 Firma Ernst Mueller K.G. Apparatus for electrostatically coating objects with liquid, solid in liquid, and/or powder-like material
US4238077A (en) * 1978-10-17 1980-12-09 Asahiokuma Sangyo Kabushiki Kaisha Spray nozzle for electrostatic airless coating
US4565318A (en) * 1982-09-30 1986-01-21 Canadian Patents & Development Limited Multi-liquid electrostatic method
US4572438A (en) * 1984-05-14 1986-02-25 Nordson Corporation Airless spray gun having improved nozzle assembly and electrode circuit connections
US4713257A (en) * 1985-02-19 1987-12-15 Kopperschmidt-Muller GmbH & Co. KG Spraying method and device for applying a film to a workpiece
US4744513A (en) * 1982-10-21 1988-05-17 Basf Farben & Faser Ag Device and process for the electrostatic coating of articles with fluids
EP0283747A2 (de) * 1987-02-24 1988-09-28 Böllhoff Verfahrenstechnik GmbH & Co. KG Elektrostatische Sprühpistole
WO1988010152A1 (en) * 1987-06-16 1988-12-29 Ransburg Corporation Spray coating device for electrically conductive coating liquids
US5011086A (en) * 1987-06-16 1991-04-30 Ransburg Corporation Spray coating device for electrically conductive coating liquids
US5086972A (en) * 1990-08-01 1992-02-11 Hughes Aircraft Company Enhanced electrostatic paint deposition method and apparatus
US20040256503A1 (en) * 2003-05-08 2004-12-23 Young Roy Earl Shielded electrode
US20060124780A1 (en) * 2004-11-12 2006-06-15 Cooper Steven C Electrostatic spray nozzle with adjustable fluid tip and interchangeable components
US20060124779A1 (en) * 2004-11-12 2006-06-15 Cooper Steven C Panel-mounted electrostatic spray nozzle system
US20090256012A1 (en) * 2008-04-09 2009-10-15 Schaupp John F Multiple charging electrode

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH555704A (de) * 1973-09-13 1974-11-15 Gema Ag Einrichtung zum beschichten von gegenstaenden mittels elektrostatisch aufgelandenen partikeln.

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3896994A (en) * 1972-03-23 1975-07-29 Walberg Arvid C & Co Electrostatic deposition coating system
US3951340A (en) * 1972-11-27 1976-04-20 Air-Industrie Electrostatic powder projection system and method
US3938740A (en) * 1973-10-04 1976-02-17 Atlas Copco Aktiebolag Nozzle for electrostatic spray gun
US3952951A (en) * 1974-03-13 1976-04-27 Firma Ernst Mueller K.G. Apparatus for electrostatically coating objects with liquid, solid in liquid, and/or powder-like material
US4238077A (en) * 1978-10-17 1980-12-09 Asahiokuma Sangyo Kabushiki Kaisha Spray nozzle for electrostatic airless coating
US4565318A (en) * 1982-09-30 1986-01-21 Canadian Patents & Development Limited Multi-liquid electrostatic method
US4744513A (en) * 1982-10-21 1988-05-17 Basf Farben & Faser Ag Device and process for the electrostatic coating of articles with fluids
US4572438A (en) * 1984-05-14 1986-02-25 Nordson Corporation Airless spray gun having improved nozzle assembly and electrode circuit connections
US4713257A (en) * 1985-02-19 1987-12-15 Kopperschmidt-Muller GmbH & Co. KG Spraying method and device for applying a film to a workpiece
EP0283747A3 (en) * 1987-02-24 1990-01-10 Kopperschmidt-Mueller Gmbh & Co Kg Electrostatic spray gun
EP0283747A2 (de) * 1987-02-24 1988-09-28 Böllhoff Verfahrenstechnik GmbH & Co. KG Elektrostatische Sprühpistole
US4842203A (en) * 1987-02-24 1989-06-27 Kopperschmidt-Mueller Gmbh & Co. Kg Nozzle assembly for spray guns
WO1988010152A1 (en) * 1987-06-16 1988-12-29 Ransburg Corporation Spray coating device for electrically conductive coating liquids
US5011086A (en) * 1987-06-16 1991-04-30 Ransburg Corporation Spray coating device for electrically conductive coating liquids
US5086972A (en) * 1990-08-01 1992-02-11 Hughes Aircraft Company Enhanced electrostatic paint deposition method and apparatus
US20040256503A1 (en) * 2003-05-08 2004-12-23 Young Roy Earl Shielded electrode
US20060124780A1 (en) * 2004-11-12 2006-06-15 Cooper Steven C Electrostatic spray nozzle with adjustable fluid tip and interchangeable components
US20060124779A1 (en) * 2004-11-12 2006-06-15 Cooper Steven C Panel-mounted electrostatic spray nozzle system
US7913938B2 (en) 2004-11-12 2011-03-29 Mystic Tan, Inc. Electrostatic spray nozzle with adjustable fluid tip and interchangeable components
US20090256012A1 (en) * 2008-04-09 2009-10-15 Schaupp John F Multiple charging electrode
US7918409B2 (en) * 2008-04-09 2011-04-05 Illinois Tool Works Inc. Multiple charging electrode

Also Published As

Publication number Publication date
JPS511252B2 (de) 1976-01-16
GB1377148A (en) 1974-12-11
DE2234026C3 (de) 1974-03-28
DE2234026A1 (de) 1973-03-01
JPS4834944A (de) 1973-05-23
DE2234026B2 (de) 1973-08-16
FR2158582A5 (de) 1973-06-15
IT962639B (it) 1973-12-31

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