EP0442019B1 - Method of operating an electrostatic and pneumatic paint spray gun - Google Patents
Method of operating an electrostatic and pneumatic paint spray gun Download PDFInfo
- Publication number
- EP0442019B1 EP0442019B1 EP90103066A EP90103066A EP0442019B1 EP 0442019 B1 EP0442019 B1 EP 0442019B1 EP 90103066 A EP90103066 A EP 90103066A EP 90103066 A EP90103066 A EP 90103066A EP 0442019 B1 EP0442019 B1 EP 0442019B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- paint
- air
- compressed
- compressed air
- outlet opening
- 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
Links
- 239000003973 paint Substances 0.000 title claims description 52
- 239000007921 spray Substances 0.000 title claims description 27
- 238000000034 method Methods 0.000 title claims description 8
- 238000001816 cooling Methods 0.000 claims description 3
- 238000011144 upstream manufacturing Methods 0.000 claims description 2
- 239000002245 particle Substances 0.000 description 6
- 238000000889 atomisation Methods 0.000 description 4
- 230000032258 transport Effects 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 3
- 239000011810 insulating material Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005686 electrostatic field Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000002966 varnish Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
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
Definitions
- the invention relates to a method for operating an electrostatic compressed air paint spray gun according to the preamble of patent claim 1.
- electrostatic compressed air paint spray guns have been known for decades and, based on the basic structure mentioned, in a wide variety of designs on the market. An example is shown in FR-A-2 522 991.
- air at a pressure of between 0.3 and 1.5 bar is mixed with paint in a mixing chamber in front of the gun mouth, and the mixture is mixed by means of a jacket air flow, the air of which is at least equal to high pressure as the mixture is driven out of the gun muzzle.
- the compressed air is provided by a compressed air network or by a compressor.
- electrostatic compressed air paint spray guns are comparatively simple. This means that no rotary drive and no rotating parts are required, as is the case with the electrostatic rotary paint spray guns.
- the ink-carrying parts, valves and seals are not exposed to high pressures, because one color print is sufficient to ensure perfect delivery of the paint liquid to the paint outlet nozzle;
- the compressed air atomizes and transports the paint.
- the compressed air supply can be made by connecting to the usually existing compressed air network; the pressure of around 6 to 8 bar, which usually prevails in these compressed air networks, is fully sufficient.
- the high voltage is either supplied by a cable from a separate high voltage generator or generated by means of so-called high voltage cascades in the gun itself.
- the invention is based on the knowledge gained from numerous test series that the disadvantages mentioned of the previous electrostatic compressed air atomizing guns are mainly due to the fact that the compressed air emerging from the perforated ring or the annular gap has considerable turbulence.
- This turbulence means that even if the middle path of the kinetic energy of the atomized paint particles or their average speed remains within limits, individual areas of the spray jet and thus parts of the paint particles get such a high speed that the particles in question not only as a result of their high kinetic energy tend to bounce back from the workpiece or fly past it (lack of color change), but especially due to its short dwell time within of the corona area of the electrode arrangement are only insufficiently charged, as a result of which the first-mentioned effect (rebound, lack of wrap) is significantly increased.
- the invention now ensures that the compressed air emerges from its outlet opening in an essentially laminar flow, that is to say as a calmed and uniform air flow. This is achieved by working below the specified limit for the ratio between the pressure before and after the compressed air outlet openings, that is to say in the so-called subsonic flow area. Of course, one will remain close to this limit in order to ensure sufficient atomization of the paint and proper transport of the atomized paint particles to the workpiece, and in particular an amount of air (air throughput through the outlet openings) is required which is at least as high as and possibly higher than that of the previously known, with a pressure ratio of, for example, 6: 1 electrostatic compressed air atomizing guns.
- the front end of the spray gun on the spray side also called the spray head, has a paint feed pipe 10, which ends at its spray end in a central paint outlet nozzle 11.
- the ink outlet opening 11 is concentrically surrounded by a compressed air outlet in the form of an annular gap 12 which is delimited by the edge of a so-called air cap 13.
- the air cap 13 is made of insulating material; the ink supply pipe 10 with nozzle 11 is preferably also made of insulating material, but could also consist of metal.
- Needle electrodes 17 protrude from the spray-side end face of the air cap 13, specifically as a needle ring concentric with the paint outlet nozzle 11.
- the needle electrodes 17 are conductively connected via lines 17a running in the air cap 13 to a contact ring 18 located on the rear end of the air cap 13.
- the spray head shown in the drawing sits at the front end of the - not shown - pistol tube of the paint spray gun, the paint being supplied via the paint supply pipe 10, the compressed air through the bores 15 and the high voltage via the contact ring 18.
- the drawn and described spray head corresponds completely to the usual state of the art in terms of structure and mode of operation.
- the pressure p 1 of the compressed air in the air chamber 16 that is to say immediately upstream of the annular gap 12, is limited to a specific maximum value, namely such that the ratio V L of the pressure p 1 to Pressure p2 in front of the spray head, i.e. downstream of the annular gap 12, is between 1.3: 1 and 1.8: 1.
- V L the ratio of the pressure p 1 to Pressure p2 in front of the spray head, i.e. downstream of the annular gap 12
- the pressure p1 must remain below 1.8 bar absolute or below 0.8 bar overpressure. Is sprayed in a closed spray booth with suction, in which the pressure p2 is slightly below atmospheric pressure, the pressure p1 must be chosen accordingly lower.
- This comparatively low pressure in the air chamber 16 is achieved in that the paint spray gun is driven by a motor-driven blower supplied with compressed air, which delivers compressed air corresponding to low pressures, namely a so-called “vacuum cleaner motor fan".
- the blower air supplied experiences a temperature increase during operation.
- a cooling element for example a cooling ring, as indicated at 19 in the drawing.
- the amount of air is sufficient, ie the throughput of compressed air through the annular gap 12 in the unit of time. Practical tests have shown that the amount of air must be as large as or greater than the amount of air that is passed through with the usual compressed air guns with a supply pressure of the compressed air of about 6 bar. This requires a considerable size of the passage area of the annular gap 12, which must be considerably larger than in the case of the conventional compressed air paint spray guns, for example by a factor of 2 or 3.
- the procedure is such that the pressure and quantity of the compressed air supplied and the size of the exit area of the annular gap are matched to the maximum paint throughput of the paint spray gun when using the toughest paints and by externally actuated air valves, namely a pressure reducing valve and / or a quantity reducing valve, the operator is given the opportunity to make an adjustment with a lower color throughput and / or with more atomizable colors.
- the electrode arrangement can be designed in the usual way, but it is expedient to arrange the electrodes close to the paint outlet, for example also as a central needle electrode in the paint outlet nozzle, in order to ensure that all paint particles pass through the corona area, i.e. the area with the highest field strength. It is also important that part of the droplet transport energy is supplied by the electrostatic field. The level of the applied voltage is therefore also an important factor and must be included in the coordination, especially when spraying paints of different electrical conductivity (water-based paint).
- color chosen here should of course include all electrostatically sprayable coating liquids, in particular varnishes of any consistency.
Landscapes
- Electrostatic Spraying Apparatus (AREA)
Description
Die Erfindung betrifft ein Verfahren zum Betreiben einer elekrostatischen Druckluft-Farbspritzpistole gemäß dem Oberbegriff des Patentsanspruchs 1. Derartige elektrostatische Druckluft-Farbspritzpistolen sind seit Jahrzehnten bekannt und, aufbauend auf dem erwähnten Grundaufbau, in den verschiedensten Ausführungen auf dem Markt. Ein Beispiel zeigt die FR-A-2 522 991. Dort wird unter Überdruck zwischen 0,3 und 1,5 bar stehende Luft in einer Mischkammer vor der Pistolenmündung mit Farbe gemischt, und das Gemisch wird mittels eines Mantelluftstromes, dessen Luft mindestens unter gleich hohem Druck wie das Gemisch steht, aus der Pistolenmündung ausgetrieben. Die Druckluft wird dabei von einem Druckluftnetz oder von einem Kompressor bereitgestellt.The invention relates to a method for operating an electrostatic compressed air paint spray gun according to the preamble of patent claim 1. Such electrostatic compressed air paint spray guns have been known for decades and, based on the basic structure mentioned, in a wide variety of designs on the market. An example is shown in FR-A-2 522 991. There, air at a pressure of between 0.3 and 1.5 bar is mixed with paint in a mixing chamber in front of the gun mouth, and the mixture is mixed by means of a jacket air flow, the air of which is at least equal to high pressure as the mixture is driven out of the gun muzzle. The compressed air is provided by a compressed air network or by a compressor.
Der Aufbau solcher elektrostatischen Druckluft-Farbspritzpistolen ist vergleichsweise einfach. So sind kein Drehantrieb und keine sich drehenden Teile erforderlich, wie dies bei den elektrostatischen Rotations-Farbspritzpistolen der Fall ist. Die farbführenden Teile, Ventile und Dichtungen, werden im Gegensatz zur luftlosen Hochdruck-Farbzerstäubung keinen hohen Drücken ausgesetzt, weil ein Farbdruck genügt, der eine einwandfreie Förderung der Farbflüssigkeit bis zur Farbaustrittsdüse gewährleistet; Zerstäubung und Transport der Farbe erfolgen ja durch die Druckluft. Die Druckluftversorgung kann durch Anschluß an das überlicherweise vorhandene Druckluftnetz erfolgen; der in diesen Druckluftnetzen meist herrschende Druck von etwa 6 bis 8 bar ist voll ausreichend. Die Hochspannung schließlich wird entweder über ein Kabel von einem gesonderten Hochspannungsgenerator geliefert oder mittels sogenannter Hochspannungskaskaden in der Pistole selbst erzeugt.The construction of such electrostatic compressed air paint spray guns is comparatively simple. This means that no rotary drive and no rotating parts are required, as is the case with the electrostatic rotary paint spray guns. In contrast to airless, high-pressure paint atomization, the ink-carrying parts, valves and seals are not exposed to high pressures, because one color print is sufficient to ensure perfect delivery of the paint liquid to the paint outlet nozzle; The compressed air atomizes and transports the paint. The compressed air supply can be made by connecting to the usually existing compressed air network; the pressure of around 6 to 8 bar, which usually prevails in these compressed air networks, is fully sufficient. Finally, the high voltage is either supplied by a cable from a separate high voltage generator or generated by means of so-called high voltage cascades in the gun itself.
Allgemein bekannt ist nun aber, daß mit den elektrostatischen Druckluft-Farbspritzpistolen nicht die ausgezeichneten Werte für den Niederschlagswirkungsgrad und insbesondere den Farbumgriff erreicht werden können, wie bei den elektrostatischen Rotations-Farbspritzpistolen. Die Fachwelt war sich wohl auch im klaren darüber, daß eine der Ursachen dafür in der gegenüber dem Rotations-Zerstäuber-Verfahren höheren kinetischen Energie der zerstäubten Farbtröpfchen liegt, hat jedoch die erwähnten Nachteile als systembedingt (Druckluft-Zerstäubung) hingenommen.It is now generally known, however, that the electrostatic compressed air paint spray guns cannot achieve the excellent values for the precipitation efficiency and in particular the color change, as with the electrostatic rotary paint spray guns. The experts were also aware that one of the causes of this was the higher kinetic energy of the atomized paint droplets than the rotary atomizer method, but accepted the disadvantages mentioned as system-related (compressed air atomization).
Aufgabe der vorliegenden Erfindung ist es nun, den Betrieb einer elektrostatischen Druckluft-Farbspritzpistole der eingangs erwähnten Art so zu verbessern, daß unter Beibehaltung der bisherigen Vorzüge, also der erwähnten konstruktiven Einfachheit, Werte für den Niederschlagswirkungsgrad und den Umgriff gewährleistet werden, wie sie bisher nur von den wesentlich aufwendigeren elektrostatischen Rotations-Farbspritzpistolen erreicht wurden. Die Lösung dieser Aufgabe ergibt sich aus Patentanspruch 1.It is an object of the present invention to improve the operation of an electrostatic compressed air paint spray gun of the type mentioned at the outset in such a way that, while maintaining the previous advantages, that is to say the constructional simplicity mentioned, values for the precipitation efficiency and the encirclement are guaranteed as they have hitherto only been possible of the much more complex electrostatic rotary spray guns. The solution to this problem results from claim 1.
Die Erfindung geht von der durch zahlreiche Versuchsreihen gewonnenen Erkenntnis aus, daß die erwähnten Nachteile der bisherigen elektrostatischen Druckluft-Zerstäuberpistolen vor allem darauf zurückzuführen sind, daß die aus dem Lochkranz bzw. dem Ringspalt austretende Druckluft beträchtliche Turbulenzen aufweist. Diese Turbulenzen führen dazu, daß selbst dann, wenn der Mittelweg der kinetischen Energie der zerstäubten Farbpartikel bzw. deren mittlere Geschwindigkeit in Grenzen bleibt, einzelne Bereiche des Sprühstrahls und damit Teile der Farbpartikel eine derart hohe Geschwindigkeit erhalten, daß die betreffenden Partikel nicht nur infolge ihrer hohen kinetischen Energie dazu neigen, vom Werkstück zurückzuprallen oder an diesem vorbeizufliegen (mangelnder Farbumgriff), sondern insbesondere infolge ihrer kurzen Verweilzeit innerhalb des Koronabereichs der Elektrodenanordnung nur ungenügend aufgeladen werden, wodurch der erstgenannte Effekt (Rückprall, mangelnder Umgriff) noch wesentlich verstärkt wird. Mit der Erfindung wird nun dafür Sorge getragen, daß die Druckluft in einer im wesentlichen laminaren Strömung aus ihrer Austrittsöffnung austritt, also als beruhigter und gleichmäßiger Luftstrom. Erreicht wird dies dadurch, daß unter dem angegebenen Grenzwert für das Verhältnis zwischen dem Druck vor und nach den Druckluft-Austrittsöffnungen gearbeitet wird, also im sogenannten subsonischen Strömungsbereich. Freilich wird man nahe diesem Grenzwert bleiben, um eine ausreichende Zerstäubung der Farbe und einen einwandfreien Transport der zerstäubten Farbpartikel zum Werkstück zu gewährleisten, und insbesondere ist eine Luftmenge (Luftdurchsatz durch die Austrittsöffnungen) erforderlich, die zumindest so hoch wie und gegebenenfalls höher ist als bei den vorbekannten, mit einem Druckverhältnis von beispielsweise 6:1 arbeitenden elektrostatischen Druckluft-Zerstäuberpistolen.The invention is based on the knowledge gained from numerous test series that the disadvantages mentioned of the previous electrostatic compressed air atomizing guns are mainly due to the fact that the compressed air emerging from the perforated ring or the annular gap has considerable turbulence. This turbulence means that even if the middle path of the kinetic energy of the atomized paint particles or their average speed remains within limits, individual areas of the spray jet and thus parts of the paint particles get such a high speed that the particles in question not only as a result of their high kinetic energy tend to bounce back from the workpiece or fly past it (lack of color change), but especially due to its short dwell time within of the corona area of the electrode arrangement are only insufficiently charged, as a result of which the first-mentioned effect (rebound, lack of wrap) is significantly increased. The invention now ensures that the compressed air emerges from its outlet opening in an essentially laminar flow, that is to say as a calmed and uniform air flow. This is achieved by working below the specified limit for the ratio between the pressure before and after the compressed air outlet openings, that is to say in the so-called subsonic flow area. Of course, one will remain close to this limit in order to ensure sufficient atomization of the paint and proper transport of the atomized paint particles to the workpiece, and in particular an amount of air (air throughput through the outlet openings) is required which is at least as high as and possibly higher than that of the previously known, with a pressure ratio of, for example, 6: 1 electrostatic compressed air atomizing guns.
Zweckmäßige Ausgestaltungen des Verfahrens nach der Erfindung sind in den Unteransprüchen gekennzeichnet.Appropriate embodiments of the method according to the invention are characterized in the subclaims.
In der Zeichnung ist eine Ausführungsform der Erfindung dargestellt, und zwar zeigt die einzige Figur schematisch das sprühseitige Vorderende der elektrostatischen Druckluft-Farbspritzpistole.In the drawing, an embodiment of the invention is shown, namely the single figure schematically shows the spray-side front end of the electrostatic compressed air paint spray gun.
Gemäß der Zeichnung weist das sprühseitige Vorderende der Spritzpistole, auch Spritzkopf genannt, ein Farb-Zuführrohr 10 auf, das an seinem Sprühende in eine zentrale Farbaustrittsdüse 11 ausläuft. Die Farbaustrittsöffnung 11 ist von einem Druckluftauslaß in Form eines Ringspalts 12 konzentrisch umgeben, der von der Randkante einer sogenannten Luftkappe 13 begrenzt wird. Ein Flansch 14 des Farbzuführrohrs 10, der mit Bohrungen 15 versehen ist, schließt eine Luftkammer 16 zwischen Farbzuführrohr 10 und Luftkappe 13 nach hinten ab. Die Luftkappe 13 besteht aus Isolierstoff; das Farbzuführrohr 10 mit Düse 11 ist vorzugsweise ebenfalls aus Isolierstoff gefertigt, könnte aber auch aus Metall bestehen. Von der sprühseitigen Stirnfläche der Luftkappe 13 stehen Nadelelektroden 17 ab, und zwar als zur Farbaustrittsdüse 11 konzentrischer Nadelkranz. Die Nadelelektroden 17 sind über in der Luftkappe 13 verlaufende Leitungen 17a mit einem an der Rückstirn der Luftkappe 13 befindlichen Kontaktring 18 leitend verbunden. Der auf der Zeichnung dargestellte Sprühkopf sitzt am Vorderende des - nicht gezeichneten - Pistolenrohrs der Farbspritzpistole, wobei über das Farbzuführrohr 10 die Farbe, durch die Bohrungen 15 hindurch die Druckluft und über den Kontaktring 18 die Hochspannung zugeführt werden. Insoweit entspricht der gezeichnete und beschriebene Sprühkopf in Aufbau und Funktionsweise völlig dem üblichen Stand der Technik.According to the drawing, the front end of the spray gun on the spray side, also called the spray head, has a
Erfindungsgemäß wird nun aber dafür Sorge getragen, daß bei in Betrieb befindlicher Farbspritzpistole der Druck p₁ der Druckluft in der Luftkammer 16, also unmittelbar stromaufwärts des Ringspalts 12, auf einen bestimmten Höchstwert begrenzt ist, nämlich derart, daß das Verhältnis VL des Drucks p₁ zum Druck p₂ vor dem Sprühkopf, also stromabwärts des Ringspalts 12, Zwischen 1,3:1 und 1,8:1 ist. Dies bedeutet, daß dann, wenn "im Freien" gespritzt wird, der Druck p₂ also 1 bar beträgt, der Druck p₁ unter 1,8 bar absolut bzw. unter 0,8 bar Überdruck bleiben muß. Wird in einer geschlossenen Spritzkabine mit Absaugung gespritzt, in welcher der Druck p₂ etwas unter Atmosphärendruck liegt, muß der Druck p₁ entsprechend niedriger gewählt werden. Erreicht wird dieser vergleichsweise niedrige Druck in der Luftkammer 16 dadurch, daß man die Farbspritzpistole durch ein motorgetriebenes Gebläse mit Druckluft versorgt, das von Hause aus Druckluft entsprechend niedrigen Drucks liefert, nämlich ein sogenanntes "Staubsauger-Motorgebläse". Die gelieferte Gebläseluft erfährt im Betrieb eine Temperatuerhöhung. Um zu vermeiden, daß die zerstäubten Farbpartikel durch die erwärmte Luft vor Erreichen des Werkstücks "eintrocknen", ist es zweckmäßig, ein Kühlelement vorzusehen, etwa einen Kühlring, wie er bei 19 in der Zeichnung angedeutet ist.According to the invention, however, care is now taken to ensure that when the paint spray gun is in operation, the pressure p 1 of the compressed air in the
Wesentlich ist, daß die im Rohr 10 zugeführte Farbe trotz des vergleichsweise geringen Drucks und der damit vergleichsweise geringen Strömungsgeschwindigkeit der Druckluft aus der Düse 11 herausgerissen, fein zerstäubt und zum Werkstück transportiert wird. Man wird deshalb im allgemeinenen nahe dem angegebenen oberen Grenzwert arbeiten, also mit einem Verhältnis VL nahe 1,8:1.It is essential that the paint supplied in the
Von ausschlaggebender Bedeutung ist dabei aber, daß die Luftmenge ausreichend ist, also der Durchsatz an Druckluft durch den Ringspalt 12 in der Zeiteinheit. Praktische Versuche haben ergeben, daß die Luftmenge genauso groß wie oder größer als die Luftmenge sein muß, die bei den üblichen Druckluftpistolen mit einem Zuführdruck der Druckluft von etwa 6 bar durchgesetzt wird. Dies erfordert eine beträchtliche Größe der Durchtrittsfläche des Ringspalts 12, die wesentlich größer sein muß als bei den üblichen Druckluft-Farbspritzpistolen, beispielsweise um den Faktor 2 oder 3. Es ist dabei wenig sinnvoll, Absolutwerte für die Luft-Durchsatzmenge und/oder die Austrittsfläche des Ringspalts 12 anzugeben, weil diese Werte abhängig sind vom gewünschten Farbdurchsatz und von der Viskosität der zu versprühenden Farbe; je höher der gewünschte Farbdurchsatz und je zäher die zu versprühende Farbe ist, umso mehr Energie muß für die Zerstäubung und den Transport der Farbe bereitgestellt werden, und nachdem die Energieerhöhung nicht durch eine Erhöhung des Drucks der Druckluft erfolgen soll, zumindest nicht über den angegebenen Grenzwert, wird dies durch die Erhöhung des Luftdurchsatzes erreicht. In der Praxis geht man dabei so vor, daß Druck und Menge der zugeführten Druckluft sowie Größe der Austrittsfläche des Ringspalts auf den maximalen Farbdurchsatz der Farbspritzpistole bei Verwendung zähester Farben abgestimmt werden und durch von außen betätigbare Luftventile, nämlich ein Druckminderventil und/oder ein Mengenminderventil, der Bedienungsperson die Möglichkeit gegeben wird, bei geringerem Farbdurchsatz und/oder bei leichter zerstäubbaren Farben eine Anpassung vorzunehmen. Die Elektrodenanordnung kann in üblicher Weise ausgebildet sein, jedoch ist es zweckmäßig, die Elektroden nahe benachbart dem Farbaustritt anzuordnen, etwa auch als zentrale Nadelelektrode in der Farbaustrittsdüse, um sicherzustellen, daß alle Farbpartikel den Koronabereich, also den Bereich höchster Feldstärke, durchlaufen. Von Bedeutung ist dabei noch, daß ein Teil der Tröpfchen-Transportenergie vom elektrostatischen Feld geliefert wird. Auch die Höhe der angelegten Spannung ist deshalb ein wesentlicher Faktor und ist in die Abstimmung einzubeziehen, insbesondere beim Versprühen von Farben unterschiedlicher elektrischer Leitfähigkeit (Wasserlack).It is of crucial importance, however, that the amount of air is sufficient, ie the throughput of compressed air through the
Praktische Versuche haben ergeben, daß mit der erfindungsgemäßen elekrostatischen Druckluft-Farbspritzpistole ein ungewöhnlich hoher Niederschlagswirkungsgrad erreicht wird, was nicht nur zu einer Kostenersparnis führt, sondern auch die Umweltverschmutzung wesentlich vermindert. Darüber hinaus wird ein ausgezeichneter Farbumgriff erzielt, etwa beim Spritzen von Rohren, wie er bisher nur mit elektrostatischen Rotations-Farbspritzpistolen möglich war.Practical tests have shown that the electrostatic compressed air paint spray gun according to the invention achieves an unusually high precipitation efficiency, which not only leads to a cost saving, but also significantly reduces environmental pollution. In addition, an excellent color change is achieved, for example when spraying pipes, which was previously only possible with electrostatic rotary paint spray guns.
Der hier gewählte Begriff Farbe soll selbstverständlich alle elektrostatisch versprühbaren Beschichtungsflüssigkeiten umfassen, insbesondere Lacke jeglicher Konsistenz.The term color chosen here should of course include all electrostatically sprayable coating liquids, in particular varnishes of any consistency.
Claims (3)
- Method for operating an electrostatic and pneumatic paint spray gun with a paint outlet nozzle (11) connected to a paint supply line (10), a compressed-air outlet opening (12) connected to a compressed-air supply line and flowing out adjacent to the paint outlet nozzle, the compressed-air outlet opening being in the form of an aperture ring or annular gap, concentrically surrounding the paint outlet nozzle, and an electrode arrangement (17) connected to a high-voltage supply (18), characterized in that the ratio (VL) of the air pressure (p1) prevailing directly upstream of the compressed-air outlet opening (12) to the air pressure (p2) prevailing downstream of the compressed-air outlet opening (12) amounts to between 1.3 : 1 and 1.8 : 1 and in that the compressed air is supplied by a vacuum-cleaner motor blower.
- Method according to claim 1, whereby the compressed air supplied has a temperature above room temperature, characterized in that before exit from the compressed-air outlet opening (12) the compressed air is cooled by means of a cooling device (9) to a temperature which is the same as or below room temperature.
- Method according to claim 1 or 2, characterized in that the electrode arrangement consists of electrode needles (17) arranged in or directly adjacent to the paint outlet opening (11).
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DK90103066.8T DK0442019T3 (en) | 1990-02-16 | 1990-02-16 | Method of operating an electrostatic pneumatic spray gun |
| DE90103066T DE59004556D1 (en) | 1990-02-16 | 1990-02-16 | Method of operating an electrostatic compressed air paint spray gun. |
| EP90103066A EP0442019B1 (en) | 1990-02-16 | 1990-02-16 | Method of operating an electrostatic and pneumatic paint spray gun |
| US07/654,342 US5188290A (en) | 1990-02-16 | 1991-02-12 | Electrostatic compressed air paint spray gun |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP90103066A EP0442019B1 (en) | 1990-02-16 | 1990-02-16 | Method of operating an electrostatic and pneumatic paint spray gun |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0442019A1 EP0442019A1 (en) | 1991-08-21 |
| EP0442019B1 true EP0442019B1 (en) | 1994-02-09 |
Family
ID=8203660
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP90103066A Expired - Lifetime EP0442019B1 (en) | 1990-02-16 | 1990-02-16 | Method of operating an electrostatic and pneumatic paint spray gun |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5188290A (en) |
| EP (1) | EP0442019B1 (en) |
| DE (1) | DE59004556D1 (en) |
| DK (1) | DK0442019T3 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| DE1577859B2 (en) * | 1965-08-26 | 1978-05-03 | Ernst Mueller Kg, 7151 Hoefen | Spray gun |
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| FR2424068A1 (en) * | 1978-04-28 | 1979-11-23 | Wagner J Ag | ELECTROSTATIC SPRAY GUN |
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| DE3214314A1 (en) * | 1982-04-19 | 1983-10-20 | J. Wagner AG, 9450 Altstätten | ELECTROSTATIC SPRAYER |
| DE3412266A1 (en) * | 1984-04-02 | 1985-10-03 | J. Wagner AG, Altstätten | ELECTROSTATIC PAINT SPRAY GUN |
| DE3412507A1 (en) * | 1984-04-03 | 1985-10-17 | J. Wagner AG, Altstätten | ELECTROSTATIC HAND SPRAY GUN |
| DE3545885C1 (en) * | 1985-12-23 | 1993-03-04 | Kopperschmidt Mueller & Co | Electrostatic spray gun |
| DE3644840A1 (en) * | 1986-04-04 | 1987-10-15 | Wagner Int | ELECTROSTATIC POWDER SPRAY GUN |
-
1990
- 1990-02-16 DE DE90103066T patent/DE59004556D1/en not_active Expired - Fee Related
- 1990-02-16 DK DK90103066.8T patent/DK0442019T3/en active
- 1990-02-16 EP EP90103066A patent/EP0442019B1/en not_active Expired - Lifetime
-
1991
- 1991-02-12 US US07/654,342 patent/US5188290A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0442019A1 (en) | 1991-08-21 |
| DE59004556D1 (en) | 1994-03-24 |
| DK0442019T3 (en) | 1995-03-13 |
| US5188290A (en) | 1993-02-23 |
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