EP0171042B1 - Vorrichtung zum elektrostatischen Beschichten von Gegenständen - Google Patents

Vorrichtung zum elektrostatischen Beschichten von Gegenständen Download PDF

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Publication number
EP0171042B1
EP0171042B1 EP85109729A EP85109729A EP0171042B1 EP 0171042 B1 EP0171042 B1 EP 0171042B1 EP 85109729 A EP85109729 A EP 85109729A EP 85109729 A EP85109729 A EP 85109729A EP 0171042 B1 EP0171042 B1 EP 0171042B1
Authority
EP
European Patent Office
Prior art keywords
spray
electrodes
electrode
spraying
diameter
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
Application number
EP85109729A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0171042A1 (de
Inventor
Hans Behr
Kurt Vetter
Rolf Schneider
Fred Luderer
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.)
Mahle Behr Industry GmbH and Co KG
Original Assignee
Behr Industrieanlagen GmbH and Co KG
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
Priority claimed from DE3429075A external-priority patent/DE3429075A1/de
Application filed by Behr Industrieanlagen GmbH and Co KG filed Critical Behr Industrieanlagen GmbH and Co KG
Publication of EP0171042A1 publication Critical patent/EP0171042A1/de
Application granted granted Critical
Publication of EP0171042B1 publication Critical patent/EP0171042B1/de
Expired 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
    • B05B5/053—Arrangements for supplying power, e.g. charging power
    • B05B5/0533—Electrodes specially adapted therefor; Arrangements of electrodes
    • 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
    • B05B5/04—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces
    • B05B5/0403—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces characterised by the rotating member
    • 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
    • B05B5/04—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces
    • B05B5/0426—Means for supplying shaping gas

Definitions

  • the invention relates to a device according to the preamble of claim 1.
  • a device of the type mentioned at the outset with a grounded rotary atomizer and a plurality of high-voltage external charging electrodes distributed around the spraying device is also known (US Pat. No. 3,393,662).
  • an essential radial spray component however, it is very difficult to protect the spray device and the charging electrodes arranged radially outside the spray head from rapid contamination by the paint particles, which can not only impair the electrical field, but also the object to be coated, for example after a color change can contaminate if they come off later.
  • the object of the invention is to create a device of the type in question which is suitable for highly conductive spraying materials which may need to be changed frequently, which on the one hand requires little insulation, and on the other hand allows good application efficiency without an overly complex (i.e. economically unfavorable) high-voltage source and largely one Avoids contamination of the electrodes generating the charging field and the spraying device.
  • the invention is based on the knowledge that not only several external electrodes under high voltage are required to achieve the object, but above all an optimal arrangement of these external electrodes with regard to the charging field.
  • the invention achieves an optimal compromise between good application efficiency (ratio of the coating to the amount of material sprayed off), relatively low operating current and minimal contamination and, at the same time, a uniform field distribution on the object to be coated, ie. H. enables a uniform coating.
  • the efficiency improves with increasing radial distance of the charging electrodes from the spray head axis, whereby the operating current is reduced at the same time.
  • the device shown contains a spray device in the form of a rotary atomizer 1 of the known bell type, the bell cup 2 forming the spray head of which can preferably be driven by an air turbine at high speed (e.g. 30,000 rpm).
  • the drive and bearing unit of the rotary atomizer 1, designated 3, essentially consists of metal.
  • a line 4 which feeds the paint or other coating material from a storage system (not shown) to the bell cup 2.
  • this line 4 for example formed by a grounded metal tube, the entire conductive coating material such as water-based paint or the like lies up to metallic paint nozzle 5 and up to the spray edge 6 of the bell cup 2 to earth potential.
  • the metallic unit 3 is electrically connected to the line 4.
  • the object to be coated (not shown), such as part of a vehicle body, which is arranged at an axial distance in front of the bell plate, is also at ground potential.
  • the spray device can enclose a metallic drive and storage unit 3 of the separate outer housing 7 made of a suitable insulating plastic, such as. B. Polyethylene terephthalate (PETP) or the like. Which can be of several parts for assembly reasons, wherein between the adjacent parts 8 and 9 of the housing may be provided with grooves 10 filled with insulating material.
  • the outer housing can also be made of metal, e.g. B. made of aluminum (which may result in a slightly lower operating current).
  • the choice of the outer housing 7 made of metal or plastic also depends, among other things, on whether the spraying device, i.e.
  • the rotary atomizer 1 is used on its own or in an arrangement (not shown) made up of a plurality of atomizers, which are approximately side by side in a common plane lie. If the axes of the atomizers are at a mutual distance which is smaller than a given minimum value, e.g. B. than 15 times the diameter of the spray edge, with the risk of contamination of the spray device or its charging electrodes by the respective neighboring spray devices, the housing 7 should at least at its axially front part (z. B. to the in the Drawable radial paragraph) are made of plastic.
  • the bell plate 2 can be made of plastic such. B. acrylic glass exist; usually you can use a common metal bell plate.
  • the electrical field required for charging the coating material must be generated by external charging electrodes 20 which are connected to high voltage.
  • these outer electrodes are each mounted on the axially projecting outer leg 22 of an angular electrode holder 21 made of plastic, the other leg 23 of which protrudes at least approximately radially, preferably perpendicularly, from the outer housing 7 and on this via a retaining ring 29 made of plastic and integrally connected to the holders 21 is attached.
  • a retaining ring 29 made of plastic and integrally connected to the holders 21 is attached.
  • only three electrode holders 21 are provided, which are distributed around the spraying device at a uniform mutual distance.
  • the electrodes 20 themselves are axially lying metal needles, suitably made of hardened steel, for example 1.2 mm in diameter, which are seated in a separate holding part 24 inserted into the front end of the leg 22 in such a way that their tip is at least approximately flush with the axially front end of the Holding part 24 completes. This minimizes the risk of contamination of the electrode 20. In the example shown, only the outer needle tip is exposed within a small depression in the holding part 24.
  • the charging electrodes 20 could also be held in the required position with respect to the bell plate 2 in another way.
  • At least two and at most three electrodes 20 must be present. While the field and thus the coating would be highly asymmetrical with only one electrode, the spray bell would also be soiled to a considerable extent and, in addition, only a low application efficiency could be achieved and these disadvantages could still be observed in a substantially weakened form even with two electrodes three electrodes are an optimum in the example of a spray device used by itself. Additional electrodes would only increase the operating current. Also you would z. B. when using a closed metal ring as the outer electrode instead of the individual electrodes used according to the invention, only a very low application efficiency and at the same time considerable contamination of both the metal ring and the spray bell.
  • the spray device is in a common arrangement of several atomizers mounted next to one another, which have a smaller distance than the minimum distance defined above and can therefore contaminate one another, only two electrodes per spray device represent the optimum.
  • an optimal radial distance of the charging electrodes 20 from the bell cup 2, ie from the spraying edge 6, is also important. It should be much larger than the diameter of the spray edge. In the example shown, two to four times the edge diameter has proven to be expedient, and approximately three times the optimum.
  • the spray edge has a diameter of 66 mm, the radial distance of the electrode from the bell axis z. B. about 225 mm, (ie 192 mm from the edge 6). If the distance is too small, the field in the vicinity of the object to be coated becomes undesirably weaker. On the other hand, too large a distance can result in contamination of the electrodes or the spray head.
  • the tips of the charging electrodes 20 are also expedient not to arrange the tips of the charging electrodes 20 in front of the spray edge plane (ie in the direction of the object to be coated), but at most in this plane and preferably behind the spray edge plane, by at most half the radial distance Electrodes 20 from the spray edge 6, preferably less than 1/5 of this distance.
  • the reset can be approximately 10-20 mm or up to approximately 1/10 of the radial distance of the electrodes 20 from the spray edge 6. As the reset increases, the operating current is somewhat smaller, but at the same time the application efficiency is reduced to a greater extent.
  • Each charging electrode 20 is connected in series with a high-impedance damping resistor 25 (e.g. in the order of 50 MOhm) to a high-voltage cable 26 which, as shown, is routed through the electrode holder 21 to the outside of the housing 7 without interruption or coupling point. From there it may lead to the high-voltage source (not shown) via a distributor feeding the other electrodes 20.
  • the potential of the high-voltage source can, as usual, be negative or also positive and have a usual value, for example 75 kV.
  • the damping resistor 25 prevents rapid current changes and reduces the operating current (by approximately 10%) without a noticeable reduction in the charging efficiency.
  • the three cables 26 coming from the electrodes 20 can each be led out of the holding ring 29 directly at the foot of the associated holder 21 and connected to one another at a remote location. However, it is also possible to at least partially lead the three cables 26 next to one another in an annular channel (not shown) provided in the retaining ring 29 and to connect them to one another either in the annular channel or preferably in a feed pipe outside the retaining ring 29. In this case, the connection point is embedded in potting compound.
  • this steering device initially consists of steering air channels 27, which open radially outside the bell cup 2 on a surface facing the object to be coated on an axially rear part of the outer housing 7.
  • the axes of the steering air ducts 27 lie in a manner known per se on a circle concentric with the atomizer with a distribution which should correspond to an angular distance between 8 ° and 20 °.
  • a second arrangement of steering air channels 27 ' is provided in the end face of the housing 7, the axes of which likewise lie on a circle which is concentric with the atomizer, but whose diameter, in contrast to the channels 27, can be smaller than that of the spray edge 6.
  • the ring diameter of which is in turn larger than the diameter of the spraying edge may also be provided near the axially front housing end. Any combination of these three possible ring arrangements can be useful.
  • the steering air can contribute in practice to reducing the risk of contamination, even with the above-mentioned arrangement of several atomizers.
  • the field strength at the spraying edge was somewhat lower, while the field in the area between the electrode holder and bell plate was larger than when the leg 23 was arranged vertically, so that paint particles arriving in this area were directed correspondingly more strongly to the electrode holder.

Landscapes

  • Electrostatic Spraying Apparatus (AREA)
EP85109729A 1984-08-07 1985-08-02 Vorrichtung zum elektrostatischen Beschichten von Gegenständen Expired EP0171042B1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE3429075A DE3429075A1 (de) 1984-08-07 1984-08-07 Vorrichtung zum elektrostatischen beschichten von gegenstaenden
DE3429075 1984-08-07
US66593284A 1984-10-29 1984-10-29
US665932 1984-10-29

Publications (2)

Publication Number Publication Date
EP0171042A1 EP0171042A1 (de) 1986-02-12
EP0171042B1 true EP0171042B1 (de) 1988-07-27

Family

ID=25823658

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85109729A Expired EP0171042B1 (de) 1984-08-07 1985-08-02 Vorrichtung zum elektrostatischen Beschichten von Gegenständen

Country Status (5)

Country Link
EP (1) EP0171042B1 (es)
AU (1) AU578111B2 (es)
CA (1) CA1259483A (es)
DE (1) DE3563917D1 (es)
ES (1) ES288858Y (es)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6896735B2 (en) 2002-01-24 2005-05-24 Behr Systems, Inc. Integrated charge ring
US7051950B2 (en) 2001-03-29 2006-05-30 Dürr Systems, Inc. Atomizer for coating unit and method for its material supply
US7328123B2 (en) 2002-09-30 2008-02-05 Durr Systems, Inc. System for collision avoidance of rotary atomizer
US7347649B2 (en) 2002-07-11 2008-03-25 Durr Systems, Inc. Powder purge tube

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3770979D1 (de) * 1986-04-18 1991-08-01 Nordson Corp Rotierende vorrichtung fuer die beschichtung durch elektrostatische zerstaeubung einer fluessigkeit.
JP2926071B2 (ja) * 1990-05-18 1999-07-28 エービービー株式会社 静電塗装装置
ES2174429T3 (es) * 1998-03-04 2002-11-01 Abb Patent Gmbh Pulverizador rotativo con fuentes de alta tension.
GB0625583D0 (en) * 2006-12-21 2007-01-31 Itw Ltd Paint spray apparatus

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3393662A (en) * 1964-12-30 1968-07-23 Ronald J. Blackwell Apparatus for electrostatic spray coating
DE2412131C3 (de) * 1974-03-13 1982-07-15 Ernst Mueller Gmbh & Co, 7057 Winnenden Vorrichtung zum elektrostatischen Überziehen von Gegenständen mit flüssigem oder pulverförmigem Überzugsmaterial
NL187613C (nl) * 1978-01-11 1991-12-02 Akzo Nv Inrichting voor het elektrostatisch verspuiten van elektrisch geleidende lak.
DE3001209C2 (de) * 1980-01-15 1985-07-25 Behr, Hans, 7000 Stuttgart Vorrichtung zum Vernebeln flüssiger Farbe, insbesondere Lackzerstäuber
JPS58190457U (ja) * 1982-06-10 1983-12-17 富士写真フイルム株式会社 静電塗装装置

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7051950B2 (en) 2001-03-29 2006-05-30 Dürr Systems, Inc. Atomizer for coating unit and method for its material supply
US6896735B2 (en) 2002-01-24 2005-05-24 Behr Systems, Inc. Integrated charge ring
US7347649B2 (en) 2002-07-11 2008-03-25 Durr Systems, Inc. Powder purge tube
US7328123B2 (en) 2002-09-30 2008-02-05 Durr Systems, Inc. System for collision avoidance of rotary atomizer

Also Published As

Publication number Publication date
EP0171042A1 (de) 1986-02-12
ES288858U (es) 1986-03-16
AU4583685A (en) 1986-02-13
AU578111B2 (en) 1988-10-13
CA1259483A (en) 1989-09-19
ES288858Y (es) 1986-10-01
DE3563917D1 (en) 1988-09-01

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