US3540653A - Apparatus for dispersing and electrically charging substances in discrete particulate form - Google Patents

Apparatus for dispersing and electrically charging substances in discrete particulate form Download PDF

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Publication number
US3540653A
US3540653A US715279A US3540653DA US3540653A US 3540653 A US3540653 A US 3540653A US 715279 A US715279 A US 715279A US 3540653D A US3540653D A US 3540653DA US 3540653 A US3540653 A US 3540653A
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United States
Prior art keywords
particles
vortex
nozzle
path
baffle plate
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
US715279A
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English (en)
Inventor
Pierre M Fabre
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.)
DE MACHINES ELECTROSTATIQUES SA
SAMES MACH ELECTROSTAT
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SAMES MACH ELECTROSTAT
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Publication date
Application filed by SAMES MACH ELECTROSTAT filed Critical SAMES MACH ELECTROSTAT
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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
    • 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
    • B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
    • B05B1/26—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means with means for mechanically breaking-up or deflecting the jet after discharge, e.g. with fixed deflectors; Breaking-up the discharged liquid or other fluent material by impinging jets
    • B05B1/262—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means with means for mechanically breaking-up or deflecting the jet after discharge, e.g. with fixed deflectors; Breaking-up the discharged liquid or other fluent material by impinging jets with fixed deflectors
    • B05B1/265—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means with means for mechanically breaking-up or deflecting the jet after discharge, e.g. with fixed deflectors; Breaking-up the discharged liquid or other fluent material by impinging jets with fixed deflectors the liquid or other fluent material being symmetrically deflected about the axis of the nozzle

Definitions

  • ABSTRACT A nozzle assembly having an axial duct through which powder suspended in a low-pressure airstream is discharged, to impinge on a baffle plate which extends in a plane perpendicular to the path of the stream. Simultaneously, high-pressure air is delivered into an annular chamber and is formed into a whirling conically diverging vortex of gas adjacent the baffle plate. The particles of powder are deflected by the plate into the vortex and are entrained thereby. A high DC Voltage is applied to the plate to electrostatically charge the particles as they are deflected.
  • This invention relates to apparatus for discharging electrically charged particles of finely divided solid materials such as powder, flakes, flock, grains and the like.
  • Apparatus of the type to which the present invention is directed while of general application, is particularly well suited for use in the electrostatic coating of objects with powder, plastic or other coating compositions.
  • the object to be coated is connected to a potential which differs considerably from the potential with which the particles are charged, whereby the charged particles follow the lines of force of the electric field and are effectively and reliably deposited over the surfaces of the object.
  • the object is at ground potential, while the particles are charged to a high DC potential.
  • the disclosed apparatus includes an axial conduit for delivering a first stream of gas containing suspended particles of coating material to a generally cylindrical vortex chamber. A further stream of gas is delivered tangentially into the chamber to entrain the particles and discharge them in the form of a whirling, diverging vortex sheet along the inner surface of a diverging outlet nozzle communicating with the chamber.
  • the outlet nozzle is electrically connected to a high DC voltage source forelectro'statically charging the particles.
  • the axial component of velocity can be kept desirably low, while at the same time the absolute linear velocity is desirably high.
  • the low axial velocity component is advantageous because it renders the charged particles more readily responsive to the action of the electric field,- while the high absolute velocity is desirable in order to ensure the requisite stable suspension of the particles in the air stream with an adequate discharge rate.
  • a more specific object of the invention is to provide such apparatus in which the axial velocity component of the discharged particles is maintained at a minimum.
  • Another object of the invention is to provide modified and highly effective means for electrostatically charging substantially all of the particles which are discharged by the apparatus.
  • Still another object of the invention is to provide a continuous process for applying a smooth and uniform coating to the articles in a rapid and straightforward manner.
  • apparatus for discharging electrically charged particles of divided solid material which comprises means for creating a generally axial stream of gas having the particles suspended in it and for directing the stream along a predetermined path, a baffle plate disposed in the path of the stream so as to deflect the same into a generally radial outflowing sheet, means creating a whirling vortex sheet of-gas surrounding the stream so as to be impinged on by the outflowing sheet, and to entrain said particles, and means connected to a high DC voltage source for electrostatically charging the particles'
  • the high voltage source is connected to the baffle plate, such that an electrostatic charge is applied to the particles substantially as they are deflected by the plate.
  • the apparatus includes a body 1 which comprises the forward section of a hand held electrostatic spray gun.
  • the body 1 is made of insulating material and has an axial conduit 2 which extends along a predetermined path and is. connected to a source (not shown) of air at relatively low pressure. Suspended within the source of air is a mass of powder particles, flock or similar solid particles to be electrostatically deposited by means of the apparatus.
  • a side longitudinal conduit 3 is also formed in the bodyl and a side longitudinal conduit 3 connected to a source-of air at higher pressure.
  • a third conduit 4 is formed longitudinally in the body 1, and this latter conduit contains aconductor 5 which is connected to the negative terminal of a source'20 of high DC voltage such as. an electrostatic generator.
  • an outer nozzle member 10 Supported inabutting relation with the flat end face of the body 1 is an outer nozzle member 10.
  • the member 10 is ofinsulating material and is held in place by a flanged screw cap 11, also of insulating material.
  • the member 10 includes a central aperture coaxial with the axial duct 2 and a conically flared inner outlet surface 14 extending outward from the central opening in contiguous relationship therewith.
  • the member 10 is formed'to define an annular air chamber 12 with the inner wall surface of the cap 11.
  • An inner nozzle 6 is provided in the form of a metal tube member which is fitted in the central opening of the outer nozzle member 10.
  • the nozzle 6 protrudes from the central open- 1 ing into the conical space formed by the surface 14 for a part of the axial length of the surface.
  • the portion of the nozzle 6 within the central opening is press fitted in a sleeve member 9.
  • the sleeve 9 is also made of electrically conductive material and projects some distance into the body I, where it is electrically connected by a wire 18 to the conductor 5.
  • the central opening of the outer member 10 is shaped and dimensioned to define a-narrow annular chamber 16 between its cylindrical wall surface and the outer wall surface of. the tube member 6.
  • the chamber 16 is connected with the air chamber 12 by passages 13 which are directed so as to connect tangentially at their inner'ends with the chamber 16.
  • a disc-shaped baffle plate 8 Projecting from adjacent the outer end of the tube member 6 are metallic spider arms 7. These arms diverge and support at their outer ends a disc-shaped baffle plate 8 which is made of conductive or semiconductive material.
  • the plate 8 is axially positioned somewhat short of the outer edge of the flared outlet surface 14 and includes a sharp circumferential edge 19 which is radially spaced by an annular gap from this surface.
  • a protruding fairshaped nose member 15 of dielectric material Secured to the outer face of the baffle 8 is a protruding fairshaped nose member 15 of dielectric material.
  • a' relatively low pressure axial gas stream containing particles of divided solid material is directed along the path defined by the conduit 2 and is discharged from the tubular nozzle 6.
  • the discharged particles impinge on the substantially flat planar surface of the baffle plate 8 and are thereby converted into a flat, radially outflowing sheet.
  • a high-pressure airstream is delivered through the conduit 3 into the pressure chamber 12 and enters the annular interstice 16 by way of the tangential passages 'l3.
  • the passages 13 create a vortex sheet which issues along the flared outlet surface 14, being forced outwardly into close proximity with the surface by centrifugal force.
  • the faired nose 15 serves to insure against the formation of a suction region beyond the baffle 8. Any such region, if present, would be liable to disturb the vortex stream and thus impair the operation of the apparatus with optimum efficien ln an illustrative spray gun constructed in accordance with the invention, the apparatus had the following characteristics; inner diameter of-tubular nozzle 6, 6 mm.; inner diameter of outlet surface 14 at its narrow end, l mm.; inner diameter of outlet surface 14 at its outlet end, 42 mm.; axial length of outlet surface 14,28 mm.; axial length of nozzle 6 projecting into the outlet surface, 10 mm.', axial spacing from end of nozzle 6 to proximate face of baffle plate 8, 10 mm.; diameter of baffle plate 8,26 mm.; diameter of interstice 16, I0 mm.
  • the supply conductor 5 was connected .to the negative terminal of an electrostatic generator the output voltage of which may be varied from 30 to 90 kv.
  • the concentration of powder in the airstream delivered to the axial duct 2 was about grammes/litre of air reduced to standard conditions.
  • the volume resistivity of the powder preferably is greater than about 100,000 ohm-centimeters.
  • Representative powders that have exhibited particular utility as coating materials include a wide variety of thermoplastic resins, such as polyethylene, polypropylene, nylon, vinyl chloride, the cellulosics, acrylics, etc., various thermosetting resins, e.g., the epoxies, several phenolic type resins and many of the silicones, for example, and various inorganic powders.
  • thermoplastic resins such as polyethylene, polypropylene, nylon, vinyl chloride, the cellulosics, acrylics, etc.
  • various thermosetting resins e.g., the epoxies, several phenolic type resins and many of the silicones, for example, and various inorganic powders.
  • Suitable powders of this latter class include talc,
  • said apparatus comprising:
  • particle delivery means for directing a gas stream containing means in juxtaposition with said baffle means for producing V a whirling vortex of gas adjacent to but spaced from the axially moving particles, said particle delivery means including a discharge portion interposed between the whirling vortex and the axially moving particles for preventing entrainment of said particles by said vortex prior to the deflection of said particles by said baffle means, said particles thereafter being deflected from said baffle means to said vortex and being entrained thereby;
  • Apparatus'for discharging electrically charged particles of divided solid material comprising:
  • particle delivery means for directing a gas stream containing particles of divided solid material along a predetermined 10 being deflected from said baffle means to said vortex and being entrained thereby; a source of high DC voltage; and means connected to said source for applying an electrostatic charge to said particles.
  • said baffle means comprising a substantially flat plate extending in a plane perpendicular to said flow path.
  • Apparatus for discharging electrically charged particles of divided solid material comprising:
  • particle delivery means for directing a first gas stream containing particles of divided solid material along a predetermined path
  • baffle means disposed in the path of said first stream for deflecting said particles in directions perpendicular to said path;
  • Apparatus'for discharging electrically charged particles of divided solid material comprising:
  • nozzle means having a powder delivery portion for directing a gas stream containing particles of divided solid material in an axial direction along a predetermined path;
  • means including a baffle plate disposed in thepath of said stream for deflecting said particles in directions transverse to said'path, to produce a generally radial outflowing sheet of particles;
  • discharge means in spaced juxtaposed relationship with said baffle plate for producing a whirling vortex of gas adjacent tobut spaced from said baffle plate, the powder delivery portion of said nozzle means being interposed between thewhirling vortex and the axially moving particles for preventing entrainment of said particles by said vortex prior to the deflection of said particles by said baffle means, said discharge means including a cylindrical chamber surrounding the nozzle means and a plurality of passages opening tangentially into said chamber;
  • said nozzle means including a discharge end extending through said cylindrical chamber and protruding therefrom into the conical space formed by said flared surface, said discharge end being disposed intermediate the smaller and larger ends of said flared surface.
  • Apparatus for discharging electrically charged particles of divided solid-material comprising:
  • nozzle means having a powder delivery portion for directing a gas stream containing particles of divided solid material along a predetermined path;
  • means including an electrically conductive baffle plate disposed in the path of said stream for deflecting said particles in directions transverse to said path, to produce a generally radial outflowing sheet of particles;
  • discharge means cooperating with said nozzle means for producing a whirling vortex of gas adjacent to but spaced from said baffle plate, the powder delivery portion of said nozzle means being interposed between the whirling vortex and the axially moving particles for preventing entrainment of said particles by said vortex prior to the deflection of said particles by said baffle means, said discharge means including a first annular chamber surrounding the nozzle means, a second annular chamber surrounding said first chamber and a plurality of tangential passages interconnecting said chambers;
  • Apparatus for discharging electrically charged particles ofdivided solid material comprising:
  • nozzle means having a powder delivery portion for directing a gas stream containing particles ofa divided solid material in an axial direction along a predetermined path;
  • baffle plate disposed in a plane perpendicular to the path of said stream for deflecting said particles in directions transverse to said path, to produce a generally radial outflowing sheet of particles
  • discharge means cooperating with said nozzle means for producing a whirling vortex of gas surrounding said sheet, the transversely deflected particles impinging on said vortex and being entrained thereby, said discharge means including a cylindrical vortex chamber, a plurality of passages opening tangentially into said chamber and a conically flared surface contiguous with the cylindrical wall of said chamber, said chamber and said surface being coaxial with the path of said stream;
  • tubular member communicating with said nozzle means for receiving the gas stream containing said particles, said tubular member extending through said cylindrical chamber and'protruding therefrom into the conical space formed by said flared surface;
  • mounting means connected to the protruding end of said tubular member for supporting said baffle plate in rigid, fixed relationship with said end, said baffle plate being located within said conical space intermediate the smaller and larger ends of said flared surface;
  • said baffle plate, said mounting means and said tubular member each being of electrically conductive material and being connected to said voltage source, said particles contacting said baffle plate to charge the particles substantially as they are deflected from said path.
  • Apparatus for discharging electrically charged particles of divided solid material comprising:
  • nozzle means having a powder delivery portion for directing a first gas stream containing particles of divided solid material along an axial path;
  • baffle means disposed in the path of said first stream for deflecting said solid particles in directions perpendicular to said path;
  • said apparatus comprising:
  • nozzle means having a powder delivery portion for directing a first gas stream containing particles of a divided solid material in an axial direction along a predetermined path;
  • baffle plate disposed in a plane perpendicular to the path of said stream for deflecting said solid particles in directions transverse to said path, to produce a generally radial outflowing sheet of particles
  • discharge means cooperating with said nozzle means for receiving a second gas stream and for producing a whirling vortex of gas from said second stream around the outflowing sheet of solid particles, said particles being deflected by said baffle plate into said vortex and being entrained thereby, said discharge means including a tubular member communicating with said nozzle means, a first annular chamber surrounding said tubular member, a
  • baffle plate being located within said conical space intermediate the smaller and larger ends of said flared surface; a source of high DC voltage; and means connected to said source for applying an electrostatic charge to said particles.

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  • Electrostatic Spraying Apparatus (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
US715279A 1967-03-22 1968-03-22 Apparatus for dispersing and electrically charging substances in discrete particulate form Expired - Lifetime US3540653A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR99888A FR92033E (fr) 1967-03-22 1967-03-22 Appareil nouveau et perfectionné pour le poudrage électrostatique d'objets

Publications (1)

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US3540653A true US3540653A (en) 1970-11-17

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US715279A Expired - Lifetime US3540653A (en) 1967-03-22 1968-03-22 Apparatus for dispersing and electrically charging substances in discrete particulate form

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US (1) US3540653A (fr)
BE (1) BE712503A (fr)
CH (1) CH470914A (fr)
DE (1) DE6603283U (fr)
DK (1) DK121994B (fr)
ES (1) ES351905A1 (fr)
FR (1) FR92033E (fr)
GB (1) GB1203499A (fr)
SE (1) SE356694B (fr)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3635400A (en) * 1970-03-27 1972-01-18 Nordson Corp Paint spraying method and apparatus
US3767116A (en) * 1972-03-23 1973-10-23 Elektro Ion Nozzle for electrostatic powder spraying apparatus
US3806029A (en) * 1973-01-24 1974-04-23 Energy Sciences Inc Shock enhancement of pressure wave energy
US4025660A (en) * 1976-01-21 1977-05-24 W. R. Grace & Co. Method of masking, venting and coating the inside of a receptacle
US4109027A (en) * 1976-01-21 1978-08-22 W. R. Grace & Co. Electrostatic coating apparatus and method
US4347984A (en) * 1974-04-01 1982-09-07 Ppg Industries, Inc. Electrostatic spray coating apparatus
US4630777A (en) * 1984-02-27 1986-12-23 Nordson Corporation Powder spray gun
US4819879A (en) * 1985-10-25 1989-04-11 Nordson Corporation Particle spray gun
US4921172A (en) * 1987-02-12 1990-05-01 Sames S.A. Electrostatic sprayer device for spraying products in powder form
US4927081A (en) * 1988-09-23 1990-05-22 Graco Inc. Rotary atomizer
US4962885A (en) * 1978-04-17 1990-10-16 Coffee Ronald A Process and apparatus for spraying liquid
DE19614192A1 (de) * 1996-04-10 1997-10-16 Abb Research Ltd Dispergiersystem für eine Pulversprüheinrichtung
DE29723226U1 (de) 1997-07-10 1998-06-04 Kolb, Robert, jun., 88046 Friedrichshafen Druckluft-Injektor zur pneumatischen Förderung eines Pulvers
US6053420A (en) * 1996-04-10 2000-04-25 Abb Research Ltd. Dispersion apparatus and process for producing a large cloud of an electrostatically charged powder/air mixture
US7802376B2 (en) * 2003-09-19 2010-09-28 Huettlin Herbert Apparatus for treating particulate material
US20160368008A1 (en) * 2015-01-12 2016-12-22 Ben-Why Liao Spray head structure slidably assembled with a nut

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4110486A (en) * 1975-01-16 1978-08-29 Adrien Lacchia Electrostatic powder coating method
DE2816850A1 (de) * 1978-04-18 1979-10-31 Mueller Ernst & Co Elektrostatische pulver-spruehpistole
AU580147B2 (en) * 1985-04-18 1989-01-05 Nordson Corporation Particle spray gun

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3635400A (en) * 1970-03-27 1972-01-18 Nordson Corp Paint spraying method and apparatus
US3767116A (en) * 1972-03-23 1973-10-23 Elektro Ion Nozzle for electrostatic powder spraying apparatus
US3806029A (en) * 1973-01-24 1974-04-23 Energy Sciences Inc Shock enhancement of pressure wave energy
US4347984A (en) * 1974-04-01 1982-09-07 Ppg Industries, Inc. Electrostatic spray coating apparatus
US4025660A (en) * 1976-01-21 1977-05-24 W. R. Grace & Co. Method of masking, venting and coating the inside of a receptacle
US4109027A (en) * 1976-01-21 1978-08-22 W. R. Grace & Co. Electrostatic coating apparatus and method
US4962885A (en) * 1978-04-17 1990-10-16 Coffee Ronald A Process and apparatus for spraying liquid
US4630777A (en) * 1984-02-27 1986-12-23 Nordson Corporation Powder spray gun
US4819879A (en) * 1985-10-25 1989-04-11 Nordson Corporation Particle spray gun
US4921172A (en) * 1987-02-12 1990-05-01 Sames S.A. Electrostatic sprayer device for spraying products in powder form
US4927081A (en) * 1988-09-23 1990-05-22 Graco Inc. Rotary atomizer
DE19614192A1 (de) * 1996-04-10 1997-10-16 Abb Research Ltd Dispergiersystem für eine Pulversprüheinrichtung
US6053420A (en) * 1996-04-10 2000-04-25 Abb Research Ltd. Dispersion apparatus and process for producing a large cloud of an electrostatically charged powder/air mixture
DE29723226U1 (de) 1997-07-10 1998-06-04 Kolb, Robert, jun., 88046 Friedrichshafen Druckluft-Injektor zur pneumatischen Förderung eines Pulvers
US7802376B2 (en) * 2003-09-19 2010-09-28 Huettlin Herbert Apparatus for treating particulate material
US20160368008A1 (en) * 2015-01-12 2016-12-22 Ben-Why Liao Spray head structure slidably assembled with a nut

Also Published As

Publication number Publication date
DK121994B (da) 1971-12-27
ES351905A1 (es) 1969-06-16
BE712503A (fr) 1968-07-31
SE356694B (fr) 1973-06-04
GB1203499A (en) 1970-08-26
CH470914A (fr) 1969-04-15
DE6603283U (de) 1969-08-28
DE1752027A1 (de) 1971-04-29
FR92033E (fr) 1968-09-13
DE1752027B2 (de) 1976-02-26

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