EP0092419A2 - Beschichtungsvorrichtung - Google Patents

Beschichtungsvorrichtung Download PDF

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Publication number
EP0092419A2
EP0092419A2 EP83302193A EP83302193A EP0092419A2 EP 0092419 A2 EP0092419 A2 EP 0092419A2 EP 83302193 A EP83302193 A EP 83302193A EP 83302193 A EP83302193 A EP 83302193A EP 0092419 A2 EP0092419 A2 EP 0092419A2
Authority
EP
European Patent Office
Prior art keywords
passage
electrode
gas stream
particles
operatively
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Withdrawn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
EP83302193A
Other languages
English (en)
French (fr)
Other versions
EP0092419A3 (de
Inventor
Nigel Paul Saunders
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.)
ELECTROPAINT Ltd
Original Assignee
ELECTROPAINT Ltd
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 ELECTROPAINT Ltd filed Critical ELECTROPAINT Ltd
Publication of EP0092419A2 publication Critical patent/EP0092419A2/de
Publication of EP0092419A3 publication Critical patent/EP0092419A3/de
Withdrawn legal-status Critical Current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

Definitions

  • This invention relates to apparatus for coating a workpiece by applying a coating material as electrically charged particles which are attracted onto the surfaces of the workpiece.
  • the invention has particular application to coating processes using a dry powder coating material but it is contemplated that it may also have application to material applied as a liquid in which case the particles will be droplets or a mist.
  • Electrostatic and electrogasdynamic coating apparatus is well known and widely utilised as a means of applying a finish or other coating to components or finished articles particularly as part of a continuous production operated automatically or semi-automatically.
  • the object of the present invention is to provide coating apparatus which is particularly efficient, reliable and consistent in operation over substantial periods of service without need for cleaning or attention, and whose operation can be readily adjusted or adapted to suit a wide range of operating requirements.
  • the invention provides a coating apparatus including non-electrically conductive structure defining a through passage leading from an upstream inlet for receiving a flow of particles of coating material from a source in use to a downstream outlet from which said particles are operatively discharged towards an article to be coated; anode and cathode electrodes within said passage across which an electrical potential is operatively applied for charging the particles in said flow; a first supply formation communicating with the passage for operatively feeding a first pressurized gas stream thereinto to induce and/or maintain said particle flow; a second supply formation connected to feed a second pressurized gas stream through an acting portion of at least one said electrode to oppose build-up of particles thereon; and means for selectively varying the output of pressurized gas fed from at least one of said supply formations in use independently of the output operatively fed from the other of said formations.
  • said at least one electrode for example the anode electrode, has a through opening forming part of said passage and through which the particle flow passes and at least the acting portion defining said opening is formed from a porous material through which the second gas stream passes into the passage.
  • the other electrode e.g. the cathode electrode
  • the other electrode may take the form of a needle centred in the passage to extend longitudinally of the direction of particle flow and having a point or tip as its acting portion disposed in spaced relationship to said acting portion of the other electrode.
  • a needle type electrode whether used in combination with the last mentioned arrangement or otherwise, may be hollow and the or a portion of the second gas stream, or possibly a third independently regulated gas stream, may be fed therethrough.
  • the first gas stream is, at least in part, directed along the passage in the immediate vicinity of and so that it sweeps along or across the acting portion of at least one said electrode before or in a region of the passage where said stream entrains the particle flow, thus contributing to prevention of particle build-up on said portion.
  • the latter stream may be directed along the passage in the downstream direction through an annular or other nozzle constituting the first supply formation so as to induce inflow of gas borne particles from said source.
  • the coating gun shown in the drawings is of the electrogasdynamic type for use in applying coating material as a dry powder onto an article.
  • the gun is in three main sections which can be dismantled by unscrewing, an inlet tube 10, a sleeve 11 at the median region, and a barrel 12 whose bore diverges toward the outlet end, the latter carrying an adjustable diffuser 13.
  • the median region shown in greater detail in Figure 2 has a number of components retained in axial relationship within sleeve 11 but which can be disassembled for cleaning or maintenance. These components define a through passage between the exit from tube 10 and the entry to barrel 12 and, starting at the upstream end, comprise a metal needle mounting block 14 carrying a cathode electrode in the form of a needle 15 projecting downstream along the central axis. Through passages 16 in block 14 lead to a central passage 17 defined by a rear cone member 18 in screw engagement with sleeve 11. The outer periphery of member 18 is shaped as to its rear portion as a cone converging to merge with a reduced diameter cylindrical front portion 19.
  • a front cone member 20 has a radial rear face carrying a sealing washer 21 locating against an interior flange 22 of sleeve 11 and a central bore positioned co-axially of front portion 19 to define an annular nozzle 23 extending forwardly from a first air chamber 24 defined within sleeve 11 and between the coned face of member 18 and the rear face of member 20.
  • Cone member 20 also has a radially outer forwardly extending coned periphery converging in the downstream direction and whose forward or downstream end abuts an anode electrode ring 25.
  • a spacer 26 is screw engaged with sleeve 11 to abut the front face of ring 25 and is in turn located against the rear end of barrel 12.
  • Components 20, 25 and 26 have co-axial through bores of uniform diameter to match and align with the rear end of the bore of barrel 12 so that flow through them is subjected to minimum turbulence.
  • Ring 25 is, in this example formed from fine grain sintered bronze, i.e. it is porous and a major portion of its rear face is exposed to a second air chamber 27 defined at the front of the coned part of member 20 within sleeve 11.
  • All the components referred to above other than the two electrodes 15, 25 and needle mounting block 14 are formed from electrically insulating material, typically a plastics material.
  • the central passage 17 of member 18 is constricted to define a narrow annular opening around the stem of needle 15 diverging at both ends, the tip of needle 15 lying just within the downstream mouth of said passage and axially spaced slightly upstream of the rear face of electrode ring 25.
  • a single air inlet 30 in the side wall of sleeve 11 communicates with the first air chamber 24 and is operatively connected to a source of pressurized air through a first control valve 31 ( Figure 1).
  • Inlet tube 10 of the gun is connected, e.g. by a further flexible duct to a source of the powder material and the electrodes 15 and 25 are connected to an electrical power circuit of known kind indicated diagrammatically at 40 operable to apply an electrical potential at high voltage across the electrodes for charging the particles passing through the gun in known manner.
  • pressurized air is admitted to first chamber 24 to exit into the through passage by way of the annular nozzle 23.
  • annular flow exits from nozzle 23 it sweeps over the exposed face of electrode ring 25 and at the same time induces an inflow of air and entrained powder particles along passage 17 and past the tip of needle 15.
  • the flow exiting from nozzle 23 also helps to prevent build-up on the operative face of ring 25.
  • the air pressure applied in chamber 27 can be regulated by means of valve 33 entirely independently of the pressure applied in the first chamber for inducing powder flow, thus control of the latter pressure can be varied e.g. to control the quantity of powder being picked up and the total air velocity through the gun, without adversely affecting the purging of ring 25. It has been found in practice that substantial improvements in gun performance are achieved with little or no powder build-up on the electrodes if the air pressure applied in chamber 27 is some three times that applied in the first chamber 24.
  • Alternative arrangements for providing the particle inducing or maintaining air flow along the central passage could be employed, i.e. other forms of nozzle or venturi arrangement and/or possibly supply of the air powder mixture under pressure into the inlet tube 10 e.g. from a fluidised bed arrangement, rather than induced flow as described above.
  • the air and powder mixture might be induced into an annular nozzle such as 23 by injecting the air flow along a central passage such as 17.
  • Air purging of a needle or other type of central electrode could be provided either in combination with the above arrangements or independently e.g. by using a hollow needle having connection to the second air chamber 27 or, possibly, to a third air or other purging gas stream which could either be controlled in common with the air supply to the second chamber 27 from valve 33 or be entirely independently controlled by a third regulating valve or other form of regulating device.
  • the threaded engagement of components 18 and 26 with sleeve 11, in combination with the screw engagement of tube 10 and barrel 12, locates all the components securely in precise working alignment and ensures that the first and second air chambers 24, 27 are sealed from each other while permitting the gun to be readily dismantled for cleaning or maintenance (though the effective purging of the electrodes ensures that need for dismantling is infrequent in service).

Landscapes

  • Electrostatic Spraying Apparatus (AREA)
EP83302193A 1982-04-20 1983-04-19 Beschichtungsvorrichtung Withdrawn EP0092419A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB08211387A GB2118865B (en) 1982-04-20 1982-04-20 Coating apparatus
GB8211387 1982-04-20

Publications (2)

Publication Number Publication Date
EP0092419A2 true EP0092419A2 (de) 1983-10-26
EP0092419A3 EP0092419A3 (de) 1984-04-25

Family

ID=10529796

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83302193A Withdrawn EP0092419A3 (de) 1982-04-20 1983-04-19 Beschichtungsvorrichtung

Country Status (2)

Country Link
EP (1) EP0092419A3 (de)
GB (1) GB2118865B (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0204437A2 (de) * 1985-05-09 1986-12-10 Nordson Corporation Pulverspritzpistolen
WO2001060527A1 (en) * 2000-02-18 2001-08-23 Altea S.R.L. Apparatus and method for supplying synthetic powders by use of an in-line venturi tube
EP1230030A2 (de) * 1999-11-12 2002-08-14 Delsys Pharmaceutical Corporation Artikel mit zerstäuber und einstellfunktion des durchflusses
DE102004055106A1 (de) * 2004-11-15 2006-05-24 P + S Pulverbeschichtungs- Und Staubfilteranlagen Gmbh Abgabevorrichtung

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2620354B2 (fr) * 1987-02-12 1990-01-05 Sames Sa Dispositif de projection electrostatique de produit en poudre
DD271611A3 (de) * 1987-10-27 1989-09-13 Verkehrswesen Hochschule Spruehpistole mit elektrokinetischer pulveraufladung
GB2277469B (en) * 1993-04-27 1996-07-24 Itw Ltd An electrostatic system
DE102004043411B3 (de) * 2004-09-02 2006-05-04 Weitmann & Konrad Gmbh & Co Kg Vorrichtung und Verfahren zum Erzeugen eines Puder-Luft-Gemisches

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1289467B (de) * 1964-01-06 1969-02-13 Devilbiss Co Vorrichtung zum elektrostatischen UEberziehen von Gegenstaenden
GB1449998A (en) * 1973-06-01 1976-09-15 Energy Innovations Electrogas dynamic production line coating system
GB1498486A (en) * 1974-09-06 1978-01-18 Air Ind Electrostatic spray nozzle for powder products
DE2852038A1 (de) * 1977-12-03 1979-06-07 Nakaya Kogyo Kk Fluessigkeitsspruehvorrichtung, insbesondere fluessigkeitsspritzpistole
US4368852A (en) * 1981-03-23 1983-01-18 Nordson Corporation Combination spray gun and pressure regulator

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5329348A (en) * 1976-08-30 1978-03-18 Ppg Industries Inc Electrostatic spraying device having gassshraud and electrostatic charging meands
JPS5534159A (en) * 1978-09-01 1980-03-10 Onoda Cement Co Ltd Powder charging device and electrostatic powder depositing device
US4258409A (en) * 1979-03-08 1981-03-24 Estey Dynamics Corporation Electrogasdynamic coating apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1289467B (de) * 1964-01-06 1969-02-13 Devilbiss Co Vorrichtung zum elektrostatischen UEberziehen von Gegenstaenden
GB1449998A (en) * 1973-06-01 1976-09-15 Energy Innovations Electrogas dynamic production line coating system
GB1498486A (en) * 1974-09-06 1978-01-18 Air Ind Electrostatic spray nozzle for powder products
DE2852038A1 (de) * 1977-12-03 1979-06-07 Nakaya Kogyo Kk Fluessigkeitsspruehvorrichtung, insbesondere fluessigkeitsspritzpistole
US4368852A (en) * 1981-03-23 1983-01-18 Nordson Corporation Combination spray gun and pressure regulator

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0204437A2 (de) * 1985-05-09 1986-12-10 Nordson Corporation Pulverspritzpistolen
EP0204437A3 (en) * 1985-05-09 1988-04-20 Nordson Corporation Improvments in and relating to powder spray guns
EP1230030A2 (de) * 1999-11-12 2002-08-14 Delsys Pharmaceutical Corporation Artikel mit zerstäuber und einstellfunktion des durchflusses
JP2003514736A (ja) * 1999-11-12 2003-04-22 デルシス ファーマシューティカル コーポレイション 流れ制御機能を備えたディフューザを有する装置
EP1230030A4 (de) * 1999-11-12 2006-03-15 Sarnoff Corp Artikel mit zerstäuber und einstellfunktion des durchflusses
WO2001060527A1 (en) * 2000-02-18 2001-08-23 Altea S.R.L. Apparatus and method for supplying synthetic powders by use of an in-line venturi tube
DE102004055106A1 (de) * 2004-11-15 2006-05-24 P + S Pulverbeschichtungs- Und Staubfilteranlagen Gmbh Abgabevorrichtung

Also Published As

Publication number Publication date
GB2118865B (en) 1985-09-25
EP0092419A3 (de) 1984-04-25
GB2118865A (en) 1983-11-09

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19851031

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Inventor name: SAUNDERS, NIGEL PAUL