EP1177050B1 - High-speed rotary atomizer with an air guide ring - Google Patents

High-speed rotary atomizer with an air guide ring Download PDF

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Publication number
EP1177050B1
EP1177050B1 EP99910346A EP99910346A EP1177050B1 EP 1177050 B1 EP1177050 B1 EP 1177050B1 EP 99910346 A EP99910346 A EP 99910346A EP 99910346 A EP99910346 A EP 99910346A EP 1177050 B1 EP1177050 B1 EP 1177050B1
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EP
European Patent Office
Prior art keywords
bell
air ring
ring
rotary atomizer
directing air
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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EP99910346A
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German (de)
French (fr)
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EP1177050A1 (en
Inventor
Gunter BÖRNER
Steffen Georgi
Josef Wittmann
Hidetoshi Yamabe
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ABB Patent GmbH
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ABB Patent GmbH
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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
    • B05B5/04—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces
    • 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
    • B05B5/0426—Means for supplying shaping gas
    • 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 invention relates to a rotary atomizer with external charging, the Applying conductive lacquers, in particular water-based lacquer, to one to be coated Surface of a body can be used.
  • Rotary atomizers are for example in DE 31 30 096 C2, DE 31 51 929 C2 and EP 0 829 306 A2.
  • the water-based paint is fed centrally to a bell that moves at high speed rotates (10000 rpm to 70000 rpm). Due to the centrifugal force Paint led to the edge of the bell and thrown from there in the form of small drops.
  • the droplets move parallel to the surface of the at the first flight moment object to be coated, which is located in the front of the atomizer.
  • a Airflow from the atomizer towards the object to be coated becomes the Droplets are then directed towards the object to be coated.
  • the air will behind the bell from the atomizer directed out of holes or slots.
  • the droplets become electrostatic charged. This is done by needle electrodes, which are attached radially around the bell are and are at negative DC potential.
  • the tension is in Range between - 40 kV and - 100 kV.
  • the high field strengths that occur the needle tips (> 25 kV / cm) lead to ionization of the air in front of the needle tips.
  • the resulting electrons attach themselves to air molecules and form negative ones Ions that are in the electric field to the bell at earth potential and move to the grounded object to be coated.
  • the higher the field strength and charge the higher the force and thus the efficiency of the order are.
  • There is an upper limit for the applied voltage From a given Voltage levels beat the uniform corona discharges into so-called Streamers around. On the one hand, this leads to a very uneven charging of the droplets and, on the other hand, the breakdown between the needle electrodes and initiate the grounded bell.
  • the invention has for its object a high-ration atomizer with external discharge and steering air ring, with which an increased efficiency with reduced Tendency to discharge is reached.
  • the steering air ring is not directly earthed for this purpose but connected to the earth potential via an ohmic resistor.
  • Fig. 1 shows a section of an atomizer with a turbine 3, which is made of a conductive material (metal and carbon). This is immediately grounded.
  • the turbine is usually equipped with an air bearing. Rolling bearings are also possible.
  • the shaft 4 of the turbine 3 is a hollow shaft in which the conductive ink supply line 5 and the solvent supply line and color return line, not shown here, are located.
  • the bell 6 is attached, which is usually made of metal.
  • the paint supplied in the paint tube 5 exits through the openings 7 and 8 and runs on the face of the bell 6 to the edge of the bell from which the paint is sprayed.
  • the turbine 4 is surrounded by a housing 1 made of non-conductive material (usually plastic).
  • the air 20, 21 is guided to the front of the atomizer by appropriate components made of insulating material 2, 9, 11 .
  • the steering air ring 13 made of conductive material has openings 12 for the steering air 21.
  • the steering air ring 13 is electrically connected to the turbine 3 via one or more parallel resistors 17 (resistance components). Good contacting can be achieved, for example, by springs 16 .
  • the conductive steering air ring 13 is provided with an insulating part 11 toward the bell, which primarily covers the edge of the steering air ring 13 .
  • Auxiliary air 20 is also passed through openings 10 in this insulating ring 11 , which avoids air turbulence at the edge of the bell.
  • the bell 6 is additionally covered on the outside with an insulating part 22 in order to further increase the security against flashovers.
  • connection between the steering air ring 13 and the grounded turbine 2 can also take place via components 23 which are made of a material which accordingly has the same electrical resistance as the resistors 17 listed above. This is shown in Fig. 3 as an embodiment.
  • the steering air ring 13 is manufactured itself from high-resistance material and to connect it to earth.
  • the resistance between the edge of the steering air ring that the needle electrodes is facing, and the earth potential is in the range of 10 M ⁇ to 500 M ⁇ .
  • the aim should be that at the edge of the steering air ring 13 , which faces the electrode holder 18 with the needle electrodes 19 , no high field strengths occur, which lead to streamer discharges.
  • a high-resistance connection can be introduced between the conductive steering air ring 13 and the plastic cover 15 , which reduces the potential.
  • 4 shows a simple exemplary embodiment. Between the steering air ring 13 and the plastic cover 15 , a ring 14 made of high-resistance material (for example plastic with added graphite or soot) is placed. This must finally touch the plastic cover 15 around the entire circumference.
  • the total flow of the atomizer is the sum of the three partial currents to the earthed object I o , to the earthed bell I g and to the steering air ring I l .
  • I I O + I l + I G.

Description

Die Erfindung bezieht sich auf einen Rotationszerstäuber mit Außenaufladung, der zum Aufbringen von leitfähigen Lacken, insbesondere Wasserlack auf eine zu beschichtende Oberfläche eines Körpers verwendet werden kann. Rotationszerstäuber sind beispielsweise in der DE 31 30 096 C2, DE 31 51 929 C2 und EP 0 829 306 A2 beschrieben.The invention relates to a rotary atomizer with external charging, the Applying conductive lacquers, in particular water-based lacquer, to one to be coated Surface of a body can be used. Rotary atomizers are for example in DE 31 30 096 C2, DE 31 51 929 C2 and EP 0 829 306 A2.

Der Wasserlack wird dabei zentral einer Glocke zugeführt, die sich mit hoher Geschwindigkeit dreht (10000 U/min bis 70000 U/min). Durch die Zentrifugalkraft wird der Lack zur Glockenkante geführt und von dort in Form kleiner Tropfen abgeschleudert. Die Tröpfchen bewegen sich damit im ersten Flug-Moment parallel zur Oberfläche des zu beschichtenden Objektes, das sich in Front des Zerstäubers befindet. Durch eine Luftströmung vom Zerstäuber in Richtung des zu beschichtenden Objektes werden die Tröpfchen dann in Richtung des zu beschichtenden Objektes gelenkt. Die Luft wird hinter der Glocke aus dem Zerstäuber aus Bohrungen oder Schlitzen geleitet. Um einen hohen Auftragswirkungsgrad zu erreichen werden die Tröpfchen elektrostatisch aufgeladen. Dies erfolgt durch Nadelelektroden, die radial um die Glocke angebracht sind und sich auf negativem Gleichspannungspotential befinden. Die Spannung liegt im Bereich zwischen - 40 kV und - 100 kV. Die dabei auftretenden hohen Feldstärken vor den Nadelspitzen (> 25 kV/cm) führen zu einer lonisierung der Luft vor den Nadelspitzen. Die dabei entstehenden Elektronen lagern sich an Luftmoleküle an und bilden negative Ionen, die sich im elektrischen Feld zu der auf Erdpotential befindlichen Glocke und zu dem geerdeten zu beschichtenden Objekt bewegen. Auf dem Weg dahin kreuzen sie die Tröpfchen und laden diese negativ auf. Auf die geladenen Tröpfchen wirkt eine Kraft in Richtung des zu beschichtenden Objektes, die durch die Wechselwirkung der elektrischen Ladung mit dem elektrischen Feld hervorgerufen wird. Dabei ist diese Kraft und damit der Auftragswirkungsgrad ist um so höher, je höher Feldstärke und Ladung sind. Für die angelegte Spannung ergibt sich eine Obergrenze. Ab einem vorgegebenen Spannungspegel schlagen die gleichmäßigen Koronaentladungen in sogenannte Streamer um. Diese führen einerseits zu einer sehr ungleichmäßigen Aufladung der Tröpfchen und können andererseits den Durchschlag zwischen den Nadelelektroden und der geerdeten Glocke einleiten.The water-based paint is fed centrally to a bell that moves at high speed rotates (10000 rpm to 70000 rpm). Due to the centrifugal force Paint led to the edge of the bell and thrown from there in the form of small drops. The droplets move parallel to the surface of the at the first flight moment object to be coated, which is located in the front of the atomizer. By a Airflow from the atomizer towards the object to be coated becomes the Droplets are then directed towards the object to be coated. The air will behind the bell from the atomizer directed out of holes or slots. To one To achieve high application efficiency, the droplets become electrostatic charged. This is done by needle electrodes, which are attached radially around the bell are and are at negative DC potential. The tension is in Range between - 40 kV and - 100 kV. The high field strengths that occur the needle tips (> 25 kV / cm) lead to ionization of the air in front of the needle tips. The resulting electrons attach themselves to air molecules and form negative ones Ions that are in the electric field to the bell at earth potential and move to the grounded object to be coated. Cross on the way there the droplets and negatively charge them. It affects the charged droplets a force in the direction of the object to be coated, caused by the interaction the electric charge is caused by the electric field. Here is this The higher the field strength and charge, the higher the force and thus the efficiency of the order are. There is an upper limit for the applied voltage. From a given Voltage levels beat the uniform corona discharges into so-called Streamers around. On the one hand, this leads to a very uneven charging of the droplets and, on the other hand, the breakdown between the needle electrodes and initiate the grounded bell.

Ein weiteres Problem besteht darin, daß durch eine Verwirbelung an der Glockenkante Tröpfchen in Richtung des Zerstäuberkörpers gelenkt werden. In US 5,775,598 wird deshalb vorgeschlagen den Lenkluftring aus einem leitfähigen Material zu fertigen und diesen mit Erdpotential zu verbinden. Zwischen dem Zerstäuberkörper und der von der Glockenkante abgesprühten Tröpfchenwolke entsteht damit eine Raumladungswolke durch den Stromfluß der Ionen von den Nadelspitzen zum geerdeten Lenkluftring. Durch die abstoßenden Kräfte der negativ geladenen Tröpfchen und den negativen lonen soll eine Verschmutzung des Zerstäuberkörpers vermieden werden. Diese Anordnung hat weiterhin den Vorteil, daß die Lenkluftöffnungen in ein metallisches Teil eingebracht werden können. Damit ist gegenüber von Kunststoffteilen eine höhere Gleichmäßigkeit der Lenkluft gewährleistet, da die Fertigungstoleranzen bei Kunststoffteilen größer sind als bei Metallteilen. Weiterhin können die teilweise beobachteten Entladungen von der Turbine durch die Lenkluftöffnungen vermieden werden, die zu einer Zerstörung dieser führen.Another problem is that due to a swirl at the edge of the bell Droplets are directed towards the atomizer body. In US 5,775,598 therefore proposed to manufacture the steering air ring from a conductive material and to connect this with earth potential. Between the atomizer body and that of the The edge of the sprayed droplet cloud is thus a space charge cloud by the current flow of the ions from the needle tips to the earthed steering air ring. By the repulsive forces of the negatively charged droplets and the negative ones Contamination of the atomizer body should be avoided. This arrangement has the further advantage that the steering air openings in a metallic part can be introduced. This is higher than plastic parts Uniformity of the steering air is guaranteed because the manufacturing tolerances for plastic parts are larger than metal parts. Furthermore, the partially observed Discharges from the turbine through the steering vents are avoided destroy them.

Diese Anordnung hat jedoch entscheidende Nachteile:

  • Der Abstand der Kante des Lenkluftrings zu den Nadelspitzen ist in der Regel kleiner als der Abstand der Glockenkante zu den Nadelspitzen. Dadurch wird nur ein kleiner Teil der an der Nadelspitze generierten negativen Elektronen zur Glockenkante gelenkt und die Feldstärke im Bereich der Glockenkante ist gering. Damit ist die Aufladung der Tröpfchen nicht ausreichend für einen hohen Wirkungsgrad.
  • Die Kante des Lenkluftringes ist mit der Kunststoffoberfläche des Zerstäuberkörpers verbunden. Damit ergeben sich Grenzflächen an denen vergleichsweise stromstarke Entladungen (Streamer) einsetzen, die zu einer Zerstörung der Kunststoffoberfläche führen.
However, this arrangement has decisive disadvantages:
  • The distance from the edge of the steering air ring to the needle tips is usually smaller than the distance from the bell edge to the needle tips. As a result, only a small part of the negative electrons generated at the needle tip is directed to the bell edge and the field strength in the area of the bell edge is low. The droplet charge is therefore not sufficient for high efficiency.
  • The edge of the steering air ring is connected to the plastic surface of the atomizer body. This results in interfaces at which comparatively powerful discharges (streamer) start, which lead to the destruction of the plastic surface.

Ein weiterer Hochrotationszerstäuber, der die Merkmale des Oberbegriffs des Anspruchs 1 aufweist, ist aus US 4 771 949 bekannt.Another high-speed rotary atomizer, which features the generic term of claim 1 is known from US 4,771,949.

Der Erfindung liegt die Aufgabe zugrunde, einen Hochrationszerstäuber mit Außenentladung und Lenkluftring anzugeben, mit dem ein erhöhter Wirkungsgrad bei verminderter Neigung zu Entladungen erreicht wird.The invention has for its object a high-ration atomizer with external discharge and steering air ring, with which an increased efficiency with reduced Tendency to discharge is reached.

Diese Aufgabe wird durch einen Hochrotationszerstäuber mit den im Anspruch 1 angegebenen Merkmalen gelöst. Ausgestaltungen sind in weiteren Ansprüchen angegeben.This object is achieved by a high-speed rotary atomizer with the specified in claim 1 Features resolved. Refinements are specified in further claims.

Mit den erfindungsgemäßen Maßnahmen gelingt es, den Lenkluftring auf ein Potential zu legen, das zwischen dem Erdpotential (Glocke und Turbine) und dem Hochspannungspotential der Nadelspitzen liegt. Dazu ist der Lenkluftring nicht direkt geerdet sondern über einen ohmschen Widerstand mit dem Erdpotential verbunden.With the measures according to the invention it is possible to bring the steering air ring to a potential to put that between the earth potential (bell and turbine) and the high voltage potential the needle tips are. The steering air ring is not directly earthed for this purpose but connected to the earth potential via an ohmic resistor.

Ausführungsbeispiele sind in Zeichnungsfiguren dargestellt und nachstehend beschrieben.Exemplary embodiments are shown in drawing figures and described below.

Es zeigen:

Fig. 1
einen Ausschnitt aus einem Zerstäuber mit Lenkluftring, Sprühglocke, und wenigstens einem Widerstandsbauteil zur hochohmigen Verbindung des Lenkluftrings mit Erdpotential,
Fig. 2
einen Zerstäuber gemäß Fig. 1 und zusätzlichem Isolierteil auf die Glocke,
Fig. 3
einen Zerstäuber gemäß Fig. 1 mit einer alternativen Ausführung der hochohmigen Verbindung,
Fig. 4
eine vergrößerte Darstellung von Maßnahmen zur Feldstärkereduzierung an Kanten des Lenklüftrings,
Fig. 5
alternative Maßnahmen zur Feldstärkereduzierung, und
Fig. 6
ein vereinfachtes elektrisches Ersatzschaltbild.
Show it:
Fig. 1
a section of an atomizer with a steering air ring, spray bell, and at least one resistance component for high-resistance connection of the steering air ring to earth potential,
Fig. 2
1 and an additional insulating part on the bell,
Fig. 3
1 with an alternative embodiment of the high-resistance connection,
Fig. 4
an enlarged representation of measures for field strength reduction at the edges of the steering air ring,
Fig. 5
alternative measures to reduce field strength, and
Fig. 6
a simplified electrical equivalent circuit diagram.

Fig. 1 zeigt einen Ausschnitt aus einem Zerstäuber mit einer Turbine 3, die aus einem leitfähigen Material (Metall und Kohlenstoff) gefertigt ist. Diese ist unmittelbar geerdet. Die Turbine ist in der Regel mit einer Luftlagerung versehen. Es sind aber auch Wälzlager möglich. Die Welle 4 der Turbine 3 ist eine Hohlwelle, in der sich die leitfähige Farbzuleitung 5 und die hier nicht dargestellten Lösemittelzuleitung und Farbrückleitung befinden. An der Stirnseite der Welle 4 ist die Glocke 6 angebracht, die in der Regel aus Metall gefertigt ist. Die im Farbrohr 5 zugeführte Farbe tritt durch die Öffnungen 7 und 8 aus und läuft auf der Stirnseite der Glocke 6 zu der Glockenkante, von der die Farbe abgesprüht wird. Die Turbine 4 ist von einem Gehäuse 1 aus nichtleitfähigen Material (in der Regel Kunststoff) umgeben. Durch entsprechende Bauteile aus Isolierstoff 2, 9, 11 wird die Luft 20, 21 zur Front des Zerstäubers geführt. Der aus leitfähigen Material gefertigte Lenkluftring 13 besitzt Öffnungen 12 für die Lenkluft 21. Der Lenkluftring 13 ist über einen oder mehrere parallele Widerstände 17 (Widerstandsbauelemente) elektrisch mit der Turbine 3 verbunden. Eine gute Kontaktierung kann z.B. durch Federn 16 erreicht werden. Fig. 1 shows a section of an atomizer with a turbine 3, which is made of a conductive material (metal and carbon). This is immediately grounded. The turbine is usually equipped with an air bearing. Rolling bearings are also possible. The shaft 4 of the turbine 3 is a hollow shaft in which the conductive ink supply line 5 and the solvent supply line and color return line, not shown here, are located. At the end of the shaft 4 , the bell 6 is attached, which is usually made of metal. The paint supplied in the paint tube 5 exits through the openings 7 and 8 and runs on the face of the bell 6 to the edge of the bell from which the paint is sprayed. The turbine 4 is surrounded by a housing 1 made of non-conductive material (usually plastic). The air 20, 21 is guided to the front of the atomizer by appropriate components made of insulating material 2, 9, 11 . The steering air ring 13 made of conductive material has openings 12 for the steering air 21. The steering air ring 13 is electrically connected to the turbine 3 via one or more parallel resistors 17 (resistance components). Good contacting can be achieved, for example, by springs 16 .

Da im Betrieb der Lenkluftring 13 auf einen anderen Potential (z.B. -10 kV) als die geerdete Glocke 6 befindet, ist zu gewährleisten, daß keine Überschläge zwischen dem Lenkluftring 13 und der Glocke 6 auftreten. In dem in Fig. 1 dargestellten Ausführungsbeispiel ist der leitfähige Lenkluftring 13 zur Glocke hin mit einem Isolierteil 11 versehen, das vor allem die Kante des Lenkluftringes 13 abdeckt. Durch Öffnungen 10 in diesem Isolierring 11 wird weiterhin eine Zusatzluft 20 geführt, die Luftverwirbelungen an der Glockenkante vermeidet. In dem in Fig. 2 dargestellten Ausführungsbeispiel ist die Glocke 6 zusätzlich an der Außenseite mit einem Isolierteil 22 bedeckt, um die Sicherheit gegen Überschläge weiter zu erhöhen.Since the steering air ring 13 is at a different potential (for example -10 kV) than the earthed bell 6 during operation, it must be ensured that no flashovers occur between the steering air ring 13 and the bell 6 . In the exemplary embodiment shown in FIG. 1 , the conductive steering air ring 13 is provided with an insulating part 11 toward the bell, which primarily covers the edge of the steering air ring 13 . Auxiliary air 20 is also passed through openings 10 in this insulating ring 11 , which avoids air turbulence at the edge of the bell. In the embodiment shown in FIG. 2 , the bell 6 is additionally covered on the outside with an insulating part 22 in order to further increase the security against flashovers.

Die Verbindung zwischen dem Lenkluftring 13 und der geerdeten Turbine 2 kann auch über Bauteile 23 erfolgen, die aus einem Material gefertigt sind, das entsprechend den gleichen elektrischen Widerstand besitzt, wie die oben aufgeführten Widerstände 17. Dies ist in Fig. 3 als Ausführungsbeispiel dargestellt.The connection between the steering air ring 13 and the grounded turbine 2 can also take place via components 23 which are made of a material which accordingly has the same electrical resistance as the resistors 17 listed above. This is shown in Fig. 3 as an embodiment.

Eine weitere in der Zeichnung nicht dargestellte Möglichkeit besteht darin, den Lenkluftring 13 selbst aus hochohmigem Material zu fertigen und mit Erde zu verbinden. Dabei sollte der Widerstand zwischen der Kante des Lenkluftringes, die den Nadelelektroden zugewandt ist, und dem Erdpotential im Bereich von 10 MΩ bis 500 MΩ liegen.Another possibility, not shown in the drawing, is the steering air ring 13 to manufacture itself from high-resistance material and to connect it to earth. there should be the resistance between the edge of the steering air ring that the needle electrodes is facing, and the earth potential is in the range of 10 MΩ to 500 MΩ.

Für einen sicheren Betrieb ist anzustreben, daß an der Kante des Lenkluftringes 13, die den Elektrodenhalter 18 mit den Nadelelektroden 19 zugewandt ist, keine hohen Feldstärken auftreten, die zu Streamer-Entladungen führen. Dazu kann zwischen dem leitfähigen Lenkluftring 13 und der Kunststoffabdeckung 15 eine hochohmige Verbindung eingebracht werden, die das Potential abbaut. Im Fig. 4 ist ein einfaches Ausführungsbeispiel dargestellt. Zwischen den Lenkluftring 13 und die Kunstoffabdeckung 15 ist ein Ring 14 aus hochohmigen Material (z.B. Kunststoff mit beigemengten Graphit oder Ruß) gelegt. Dieser muß um den gesamten Umfang schlüssig die Kunststoffabdekkung 15 berühren. Luftspalte müssen auf jeden Fall sowohl zwischen dem hochohmigen Ring 14 und der isolierenden Kunststoffabdeckung 15 als auch zwischen dem hochohmigen Ring 14 und dem Lenkluftring 13 vermieden werden. Eine weitere Möglichkeit besteht in dem in Fig. 5 dargestellten Überzug der Vorderkante der Kunststoffabdeckung 15 mit einem hochohmigen Material 24, z. B. Lack. Dabei ist wiederum darauf zu achten, daß keine Luftspalte entstehen. Es sind auch Kombinationen der beiden in Fig. 4 und Fig. 5 dargestellten Maßnahmen möglich.For safe operation, the aim should be that at the edge of the steering air ring 13 , which faces the electrode holder 18 with the needle electrodes 19 , no high field strengths occur, which lead to streamer discharges. For this purpose, a high-resistance connection can be introduced between the conductive steering air ring 13 and the plastic cover 15 , which reduces the potential. 4 shows a simple exemplary embodiment. Between the steering air ring 13 and the plastic cover 15 , a ring 14 made of high-resistance material (for example plastic with added graphite or soot) is placed. This must finally touch the plastic cover 15 around the entire circumference. In any case, air gaps must be avoided both between the high-resistance ring 14 and the insulating plastic cover 15 and between the high-resistance ring 14 and the steering air ring 13 . A further possibility consists in the example shown in Fig. 5 covering the front edge of the plastic cover 15 with a high impedance material 24 such. B. paint. It is important to ensure that there are no air gaps. Combinations of the two measures shown in FIGS. 4 and 5 are also possible.

Das stark vereinfachte elektrische Ersatzschaltbild ist in Fig. 6 dargestellt. Der elektrische Stromkreis besteht aus Gasentladungsstrecken

  • zwischen den Nadelspitzen und dem geerdeten, zu beschichtenden Objekt 25,
  • zwischen den Nadelspitzen und der geerdeten Glocke 26,
  • zwischen den Nadelelektroden und dem Lenkluftring 27,
und einem Widerstand 28 zwischen Lenkluftring und Erde. Die Strom - Spannungs - Kennlinien der Gasentladungsstrecken können durch folgende Gleichungen approximiert werden:
  • zwischen den Nadelspitzen und dem geerdeten zu beschichtenden Objekt Io = co (U - U0o)2;
  • zwischen den Nadelspitzen und der geerdeten Glocke Ig = cg(U - U0g)2;
  • zwischen den Nadelelektroden und dem Lenkluftring Il = cl (U - Ul - U0l)2
The highly simplified electrical equivalent circuit diagram is shown in FIG. 6 . The electrical circuit consists of gas discharge lines
  • between the needle tips and the grounded object 25 to be coated,
  • between the needle tips and the earthed bell 26 ,
  • between the needle electrodes and the steering air ring 27 ,
and a resistor 28 between the steering air ring and earth. The current-voltage characteristics of the gas discharge paths can be approximated using the following equations:
  • between the needle tips and the grounded object to be coated I O = c O (U - U 0o ) 2 ;
  • between the needle tips and the grounded bell I G = c G (U - U 0g ) 2 ;
  • between the needle electrodes and the steering air ring I l = c l (U - U l - U 0l ) 2

Die Spannung am Lenkluftring Ul ergibt sich aus dem Strom zum Lenkluftring Il und dem elektrischen Widerstand zwischen Lenkluftring und Erde Rl Ul = Il Rl. The voltage at the steering air ring U l results from the current to the steering air ring I l and the electrical resistance between the steering air ring and earth R l U l = I l R l.

Der Gesamtstrom des Zerstäubers ist die Summe der drei Teilsiröme zum geerdeten Objekt Io, zur geerdeten Glocke Ig und zum Lenkluftring Il. I = Io + Il + Ig. The total flow of the atomizer is the sum of the three partial currents to the earthed object I o , to the earthed bell I g and to the steering air ring I l . I = I O + I l + I G.

Im elektrischen Sinne handelt es sich hier um eine Mehrelektrodenanordnung mit verschiedenen Potentialen. In erster Näherung kann jedoch davon ausgegangen werden, daß die Parameter co, cg, cl, U0o, U0g und U0l allein von der Geometrie und nicht von Potentialen abhängig sind. Damit wird der Zerstäuber in erster Näherung durch die aufgeführten fünf Gleichungen beschrieben.In the electrical sense, this is a multi-electrode arrangement with different potentials. In a first approximation, however, it can be assumed that the parameters c o , c g , c l , U 0o , U 0g and U 0l depend solely on the geometry and not on potentials. The atomizer is thus described in a first approximation by the five equations listed.

Experimentelle Untersuchungen haben ergeben, daß sich eine sehr gute Leistung des Zerstäubers (hoher Auftragswirkungsgrad und geringe Verschmutzung) ergibt, wenn der Strom zur Glocke ca. 400 µA, der Strom zum Objekt ca. 100 µA und der Strom zur Glocke ca. 100 µA beträgt. Diese Abstimmung hängt nicht nur vom Widerstand sondern auch von der Position der Nadelelektroden ab. Generell erweisen sich Widerstände im Bereich von 10 MΩ bis 500 MΩ als geeignet. Experimental studies have shown that the Atomizer (high application efficiency and low pollution) if the current to the bell approx. 400 µA, the current to the object approx. 100 µA and the current to Bell is approx. 100 µA. This vote depends not only on resistance but also also from the position of the needle electrodes. In general, resistance to the Range from 10 MΩ to 500 MΩ as suitable.

BezugszeichenlisteLIST OF REFERENCE NUMBERS

11
Gehäuse aus Isoliermaterial (z.B. Kunststoff)Housing made of insulating material (e.g. plastic)
22
Bauteil aus KunststoffPlastic component
33
Turbine mit Luftlagerung (leitfähig mit Erdpotential verbunden)Turbine with air bearing (conductively connected to earth potential)
44
Hohlwelle (leitfähig)Hollow shaft (conductive)
55
Farbrohr (leitfähig)Paint tube (conductive)
66
Glocke (leitfähig)Bell (conductive)
77
Farb- und LösemittelöfnungenPaint and solvent openings
88th
Farb- und SpülmittelöffnungenPaint and detergent openings
99
Bauteil aus IsolierstoffInsulating component
1010
Öffnung für Zusatzluft (Bohrungen oder Spalt)Additional air opening (holes or gap)
1111
Bauteil aus IsolierstoffInsulating component
1212
Öffnungen für Lenkluft (Bohrungen oder Spalt)Openings for steering air (holes or gap)
1313
Lenkluftring aus leitfähigen MaterialSteering air ring made of conductive material
1414
Ring aus hochohmigen Material zur FeldsteuerungRing made of high-resistance material for field control
1515
Ring aus IsolierstoffInsulation ring
1616
Federfeather
1717
Ohmscher Widerstand BauteilOhmic resistance component
1818
Elektrodenhalterelectrode holder
1919
Nadelelektrode (negative Gleichspannung)Needle electrode (negative DC voltage)
2020
Zusatzluft zur Vermeidung von Verwirbelungen an der GlockenkanteAdditional air to avoid turbulence at the edge of the bell
2121
Lenkluftdirecting air
2222
Außenisolierung der GlockeExternal insulation of the bell
2323
Bauteil aus hochohmigen MaterialComponent made of high-resistance material
2424
Überzug aus hochohmigen MaterialCover made of high-resistance material
2525
Ersatzschaltbild für die Gasentladungsstrecke zwischen Nadelelektroden und geerdeten zu beschichtenden ObjektEquivalent circuit for the gas discharge gap between needle electrodes and grounded object to be coated
2626
Ersatzschaltbild für die Gasentladungsstrecke zwischen Nadelelektroden und geerdeter Glocke Equivalent circuit for the gas discharge gap between needle electrodes and grounded bell
2727
Ersatzschaltbild für die Gasentladungsstrecke zwischen Nadelelektroden und LenkluftringEquivalent circuit for the gas discharge gap between needle electrodes and Directing air ring
2828
Widerstand zwischen leitfähigen Lenkluftring und ErdeResistance between conductive steering air ring and earth
Verwendete FormelzeichenFormula symbols used

UU
Spannung an den NadelspitzenTension at the needle tips
Ul U l
Spannung am LenkluftringTension on the steering air ring
II
Gesamtstrom des ZerstäubersTotal atomizer flow
Io I o
Strom von den Nadelspitzen zum geerdeten zu beschichtenden ObjektCurrent from the needle tips to the grounded object to be coated
Ig I g
Strom von den Nadelspitzen zur geerdeten GlockeStream from the tips of the needles to the grounded bell
Il I l
Strom von den Nadelspitzen zum LenkluftringStream from the needle tips to the steering air ring
Rl R l
Widerstand zwischen leitfähigen Lenkluftring und ErdeResistance between conductive steering air ring and earth
co, cg, cl, U0o, U0g und U0l c o , c g , c l , U 0o , U 0g and U 0l
Parameter der GasentladungsstreckenParameters of the gas discharge lines

Claims (10)

  1. High-speed rotary atomizer for applying electrically conductive paint, in particular water-based paint, the rotary atomizer having:
    a) an electrode arrangement (18, 19) for electrostatic external charging,
    b) an electrically conductive and earthed spraying bell (6), which can be set in rotation by means of driving devices (3, 4) which are located in an atomizer housing (1) of electrically insulating material, characterized by
    c) a directing air ring (13) of electrically conductive material, with which directing air (21) can be blown out and which operationally carries high-voltage potential (for example -10 kV), where
    d) means (13, 16, 17) which form an ohmic resistance in the range from 10 MΩ to 500 MΩ and establish an electrical connection of the directing air ring (13) to earth potential via this resistance are present.
  2. High-speed rotary atomizer according to Claim 1, characterized in that one or more parallel resistance components (17) are arranged as means for connecting the directing air ring (13) to earth potential.
  3. High-speed rotary atomizer according to Claim 2, characterized in that at least one spring element (16) is arranged for the electrical contacting of the resistance components (17).
  4. High-speed rotary atomizer according to Claim 1, characterized in that the directing air ring (13) is produced from a high-impedance material, so that the directing air ring (13) itself is used as the means for connection to earth potential, an ohmic resistance in the range from 10 MΩ to 500 MΩ being established between an edge of the directing air ring facing the electrodes (19) and a component carrying earth potential.
  5. High-speed rotary atomizer according to one of the preceding claims, characterized in that the directing air ring (13) is covered in a region facing the bell (6) by an electrically insulating insulating part (11), whereby a minimum distance of 4 mm to 15 mm is set between the uncovered directing air ring (13) and the bell (6).
  6. High-speed rotary atomizer according to one of the preceding claims, characterized in that the bell (6) is covered on its outer side, facing the directing air ring (13), by an electrically insulating insulating part (11).
  7. High-speed rotary atomizer according to one of the preceding claims, characterized in that a part of the directing air ring (13) facing the electrodes (19) is covered by means of an insulating-material ring (15), and a ring (14) of high-impedance material is inserted between the insulating-material ring (15) to reduce the field strength, air gaps between the components (13, 14, 15) being avoided by suitable shaping.
  8. High-speed rotary atomizer according to one of the preceding claims, characterized in that the directing air ring (13) is covered in a partial region of its surface by an insulating part (11), which in particular covers an edge of the directing air ring (13) facing the bell (6) in order to reduce the risk of electrical breakdowns between the ring (13) and the bell (6).
  9. High-speed rotary atomizer according to Claim 8, characterized in that additional air (20) can be blown through openings (10) in the insulating part (11) into the intermediate space between the insulating part (11) and the bell (6), whereby air vortices at the edge of the bell can be avoided.
  10. High-speed rotary atomizer according to one of Claims 7 to 9, characterized in that the front edge of the insulating-material ring (15) is covered by means of a coating (24) of a high-impedance material, in particular a paint, in order to reduce the field strength in the region of the front edge.
EP99910346A 1999-03-16 1999-03-16 High-speed rotary atomizer with an air guide ring Expired - Lifetime EP1177050B1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP1999/001705 WO2000054888A1 (en) 1999-03-16 1999-03-16 High-speed rotary atomizer with an air guide ring

Publications (2)

Publication Number Publication Date
EP1177050A1 EP1177050A1 (en) 2002-02-06
EP1177050B1 true EP1177050B1 (en) 2003-01-22

Family

ID=8167242

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99910346A Expired - Lifetime EP1177050B1 (en) 1999-03-16 1999-03-16 High-speed rotary atomizer with an air guide ring

Country Status (9)

Country Link
US (1) US6565021B2 (en)
EP (1) EP1177050B1 (en)
JP (1) JP4343445B2 (en)
KR (1) KR100492233B1 (en)
AU (1) AU2933299A (en)
CA (1) CA2367140C (en)
DE (1) DE59904125D1 (en)
ES (1) ES2189399T3 (en)
WO (1) WO2000054888A1 (en)

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DE102011006617B4 (en) 2011-04-01 2018-08-16 Bayerische Motoren Werke Aktiengesellschaft Rotary atomizer with external electrodes for coating a workpiece

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JP2004167411A (en) * 2002-11-21 2004-06-17 Anest Iwata Corp High voltage generator for electrostatic coating
US6929823B2 (en) * 2003-05-01 2005-08-16 E. I. Du Pont De Nemours And Company Process for the high-speed rotary application of liquid, pigmented coating agents
JP2007000826A (en) * 2005-06-27 2007-01-11 Duerr Japan Kk Bell type coating apparatus
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DE102015000709A1 (en) * 2015-01-21 2016-07-21 Dürr Systems GmbH Bell plate or shaping air ring with non-metallic material for spark prevention
JP6745987B2 (en) * 2017-08-18 2020-08-26 アーベーベー・シュバイツ・アーゲーＡＢＢ Ｓｃｈｗｅｉｚ ＡＧ Electrostatic coating machine
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Also Published As

Publication number Publication date
ES2189399T3 (en) 2003-07-01
CA2367140A1 (en) 2000-09-21
WO2000054888A1 (en) 2000-09-21
US6565021B2 (en) 2003-05-20
KR100492233B1 (en) 2005-05-31
JP4343445B2 (en) 2009-10-14
US20020066809A1 (en) 2002-06-06
AU2933299A (en) 2000-10-04
DE59904125D1 (en) 2003-02-27
JP2002538957A (en) 2002-11-19
KR20020003189A (en) 2002-01-10
EP1177050A1 (en) 2002-02-06
CA2367140C (en) 2007-06-12

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