EP1115499B1 - Powder coating device - Google Patents

Powder coating device Download PDF

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Publication number
EP1115499B1
EP1115499B1 EP99927927A EP99927927A EP1115499B1 EP 1115499 B1 EP1115499 B1 EP 1115499B1 EP 99927927 A EP99927927 A EP 99927927A EP 99927927 A EP99927927 A EP 99927927A EP 1115499 B1 EP1115499 B1 EP 1115499B1
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EP
European Patent Office
Prior art keywords
air
powder
flow
control device
line
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EP99927927A
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German (de)
French (fr)
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EP1115499A1 (en
Inventor
Hans Peter Michael
Gerald Haas
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Gema Switzerland GmbH
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Gema Switzerland 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
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/14—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas designed for spraying particulate materials
    • B05B7/1404—Arrangements for supplying particulate material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/14—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas designed for spraying particulate materials
    • B05B7/1404—Arrangements for supplying particulate material
    • B05B7/1472—Powder extracted from a powder container in a direction substantially opposite to gravity by a suction device dipped into the powder
    • 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
    • B05B5/16—Arrangements for supplying liquids or other fluent material
    • B05B5/1683—Arrangements for supplying liquids or other fluent material specially adapted for particulate materials

Definitions

  • the invention relates to a powder coating apparatus according to the preamble of claim 1.
  • a powder spray coating apparatus of this kind is known from EP-B-0 412 289 ( US 5,131,350 ) known.
  • German Patent 1,266,685 is the basic principle of an injector for the pneumatic conveying of coating powder known.
  • EP-B-0 412 289 is an electrostatic Powder coating device known, which contains in a conveying air line and in an additional air line per a pressure regulator and in a common compressed air supply line to the conveying air line and the additional air line, a display device for displaying the total air volume flow.
  • the pressure regulator can also be controlled automatically by a microcomputer.
  • a powder line leading from the injector to a spray device or container a minimum amount of air is required to prevent powder deposits and flow pulsations in the powder line.
  • the powder flow rate should be as constant as possible in the powder line or not fluctuate greatly, regardless of the amount of powder delivered per unit time.
  • Air divider valves which have a throttle valve in the conveying air line and a throttle valve in the additional air line, which are mechanically coupled to each other and are manually or motor-adjustable, to the same extent as one throttle valve is opened, the other Throttling valve is closed further.
  • the valve bodies and their valve seats can be manually adjusted relative to one another to have a default of the amount by which one airflow should be greater or less than the other air flow.
  • the object of the invention is to achieve at all times reproducible settings of the conveying air and the additional air and the amount of powder delivered per unit time, without precision problems in the production occur and without requiring specially trained operators, and also without the need for longer interruptions of Coating operation with changing coating conditions.
  • control device When using an electric stepper motor, no actual value feedback to the control device is required for control or regulation because the control device always automatically knows how many steps the stepper motors have made in one or the other direction of rotation.
  • the control device is a completely electronic Control device, preferably with one or more microprocessors.
  • the control device can be automatically controlled or regulated by a superordinate control station or main computer depending on the objects to be coated, for example, when changing the type of powder, when changing the coating thickness to be generated and / or when changing the clock speed or conveying speed, with which the objects to be coated are transported past a spraying device.
  • the powder coating apparatus comprises an electronic control device 2, which comprises an electric stepper motor 4 for setting a variable flow restrictor 6 in a conveying air line 8 and an electric stepper motor 14 for variably setting an adjustable throttle 16 in an additional air line 18 via electrical lines 10th or 20 electrically controls, in Dependent on a nominal powder flow rate (delivered amount of powder per unit of time) and depending on a nominal total air volume flow (per unit time delivered total air) consisting of conveying air of the conveying air line 8 and additional air of the additional air line 18.
  • an electronic control device 2 comprises an electric stepper motor 4 for setting a variable flow restrictor 6 in a conveying air line 8 and an electric stepper motor 14 for variably setting an adjustable throttle 16 in an additional air line 18 via electrical lines 10th or 20 electrically controls, in Dependent on a nominal powder flow rate (delivered amount of powder per unit of time) and depending on a nominal total air volume flow (per unit time delivered total air) consisting of conveying air of the conveying air line 8 and additional air of the additional air line 18.
  • the electronic control device 2 may also contain one or more computer programs, which set the powder flow rate and the total air volume flow in dependence on the objects to be coated, their conveying or clock speed, the coating thickness to be generated, the type of powder to be used (Grain size, plastic, ceramics) and / or other criteria automatically sets.
  • Such a computer program or such computer programs may be contained instead of in the control device 2 in a higher-level control system or control station 30, which communicates with the control device 2 via a data bus 32 in data exchange.
  • the upstream ends of the conveying air line 8 and the additional air line 18 are connected via a pressure regulator 34 to a common compressed air source 36.
  • the downstream ends of the conveying air line 8 and the additional air line 18 are connected to an injector 38.
  • the conveying air flow of the conveying air line 8 flows from a Injector 40 through a negative pressure region 42 in which it generates a negative pressure and thereby sucks coating powder 46 from a powder container 44, then into a capture channel 48 and from there together with the sucked powder through a powder line 50 to another container or accordingly Fig. 1 to a spraying device 52.
  • the spraying device 52 is preferably of the type which electrostatically charges powders. It may be a manual or automatic spray gun or a rotary atomizer or the like. It sprays the pneumatically conveyed powder 46 onto articles 54 to be coated, which are automatically transported by a transport device 56 past the spray side of the spraying device.
  • a powder suction opening 58 of the injector 38 opens into the vacuum region 42.
  • the container 44 can also be arranged above the injector 38 instead of underneath the injector 38.
  • the downstream end of the additional air line 18 is connected to an additional air opening 60 of the injector 38, from which the additional air flows into the conveying air-powder flow of the catching channel 48.
  • a plurality of additional air lines may be provided, these may open into the catch channel 48 or upstream or downstream thereof in the conveying air-powder flow path.
  • stepper motors 4 and 14 instead of electric stepper motors 4 and 14 as servo motors, other motors may be used, such as servomotors. In all cases, the coordinated control or regulation of the chokes 6 and 16 by their motors is purely electrical by the electronic control device 2.
  • the use of electric stepper motors instead of hydraulic motors has the advantage that the control device 2 at any time "white", as the associated Throttle 6 or 16 is set, since it automatically knows how many steps of the respective stepper motor was rotated in one direction or the other of them.
  • the throttles 6 and 16 may be adjustable or adjustable valves or taps.
  • a display device 60 displays the setpoint values and actual values of the delivery air volume flow, the additional air volume flow, the total volume flow of conveying air and additional air, and the powder flow rate.
  • the delivered amount of powder per unit time (powder rate) is approximately proportional to the per unit time promoted conveying air amount of the conveying air line 8. Therefore, only the conveying air needs to be adjusted with the keys 22 and 23 to set a desired amount of powder.
  • the controller 2 then automatically adjusts the additional air rate by the servomotor 14 and the throttle 16 so that despite the changed delivery rate of the total air flow rate (total air rate) remains at the set value.
  • the delivery air rate and the additional air rate change, with constant air pressure at the pressure regulator 34, only proportional to a change in the flow cross section of their chokes 6 and 16, when the flow resistance downstream of them is very small.
  • the flow resistance is so great that the delivery air rate and the additional air rate do not change linearly to changes in the flow cross sections of the throttles 6 and 16.
  • the non-linear dependence for at least one or more flow resistances is stored diagrammatically such that the control device 2, the throttles 6 and 16 by the servo motors 4 and 14 in response to setpoint specifications, for example on the buttons 22, 23, 24 and 25, non-linearly so that there is a change in the setpoint change linearly the delivery air rate and / or the additional air rate.
  • the spray device 50 is a manual spray gun, on which the buttons 22 and 23, preferably also the buttons 24 and 25 are arranged and manually operated with a finger.

Landscapes

  • Electrostatic Spraying Apparatus (AREA)
  • Nozzles (AREA)
  • Seal Device For Vehicle (AREA)
  • Encapsulation Of And Coatings For Semiconductor Or Solid State Devices (AREA)

Abstract

Powder-coating equipment comprises two throttles (6, 16) each mounted in one of a conveyance-air line (8) and a supplemental-air line (18). The throttles' flow impedance' are adjustable in a motorized manner by providing throttle with its own adjustment motor (4, 14). The adjustment motors, such as electric stepping motors and/or servo-motors are driven by an electronic control unit (2).

Description

Die Erfindung betrifft eine Pulverbeschichtungsvorrichtung gemäß dem Oberbegriff von Anspruch 1.The invention relates to a powder coating apparatus according to the preamble of claim 1.

Eine Pulversprühbeschichtungsvorrichtung dieser Art ist aus der EP-B-0 412 289 ( US 5 131 350 ) bekannt.A powder spray coating apparatus of this kind is known from EP-B-0 412 289 ( US 5,131,350 ) known.

Wie der vielfältige Stand der Technik zeigt, wurde schon durch viele Entwicklungsarbeiten in verschiedenen Richtungen versucht, optimale Betriebseinstellungen mit einfach durchzuführenden Maßnahmen zu erreichen. Dies ist bis jetzt noch nicht zufriedenstellend gelungen. Aus der DE-Patentschrift 1 266 685 ist das Grundprinzip eines Injektors zur pneumatischen Förderung von Beschichtungspulver bekannt. Aus der genannten EP-B-0 412 289 ist eine elektrostatische Pulverbeschichtungseinrichtung bekannt, welche in einer Förderluftleitung und in einer Zusatzluftleitung je einen Druckregler und in einer gemeinsamen Druckluft-Zufuhrleitung zu der Förderluftleitung und der Zusatzluftleitung ein Anzeigegerät zur Anzeige des Gesamtluft-Volumenstromes enthält. Bei einer Änderung des Förderluft-Volumenstromes durch Verstellung seines Druckreglers, um den Pulverstrom entsprechend zu ändern, kann die dadurch entstehende Veränderung des Gesamtluft-Volumenstromes durch entsprechende Verstellung des Druckreglers der Zusatzluftleitung unter Berücksichtigung der Anzeige am Anzeigegerät wieder aufgehoben werden. Statt manuell können die Druckregler auch durch einen Mikrocomputer automatisch gesteuert werden. In einer vom Injektor zu einer Sprühvorrichtung oder einem Behälter führenden Pulverleitung ist eine Mindestmenge an Luft erforderlich, um Pulverablagerungen und Strömungspulsationen in der Pulverleitung zu vermeiden. Die Pulverströmungsgeschwindigkeit soll in der Pulverleitung möglichst konstant sein oder nicht stark schwanken, unabhängig von der pro Zeiteinheit geförderten Pulvermenge. Deshalb muß mehr Zusatzluft zugegeben werden, wenn die Förderluftmenge zur Förderung einer kleinen Pulvermenge pro Zeiteinheit (Pulvermengenstrom) soweit reduziert werden muß, daß in der Pulverleitung ohne die Zusatzluft nicht mehr ausreichend Gesamtluft vorhanden wäre. Die Zusatzluft wird nach einem Unterdruckbereich des Injektors, in welchem die Förderluft Pulver ansaugt, in den Förderluft-Pulverstrom eingeleitet. Gemäß abgewandelter Ausführungsform oder zusätzlich kann jedoch auch Zusatzluft in den Unterdruckbereich eingeleitet werden, um die Stärke des Unterdruckes oder Vakuums, welches von der Förderluft erzeugt wird, zu variieren. Somit wird bei Reduzierung des Förderluft-Volumenstromes der Zusatzluft-Volumenstrom erhöht, und umgekehrt. Eine ähnliche Vorrichtung mit je einem Druckregler in einer Förderluftleitung und in einer Zusatzluftleitung ist auch aus Fig. 4 der US-A-3 625 404 bekannt. Aus dieser gleichen US-Schrift und aus der DE-A-44 09 493 sind auch Luft-Teiler-Ventile bekannt, welche ein Drosselventil in der Förderluftleitung und ein Drosselventil in der Zusatzluftleitung aufweisen, welche mechanisch miteinander gekoppelt sind und manuell oder motorisch verstellbar sind, wobei in gleichem Maße, wie das eine Drosselventil weiter geöffnet wird, das andere Drosselventil weiter geschlossen wird. Bei dem in Fig. 3 der genannten US-Patentschrift gezeigten Luft-Teiler-Ventil können die Ventilkörper und ihre Ventilsitze relativ zueinander manuell eingestellt werden, um eine Voreinstellung des Maßes zu haben, um welches die eine Luftströmung größer oder kleiner sein soll als die andere Luftströmung. Diese mechanisch gekoppelten Drosselventile haben jedoch den Nachteil, daß die genannte Voreinstellung des Unterschiedes zwischen Förderluft-Volumenstrom und Zusatzluft-Volumenstrom nur für eine ganz bestimmte Pulversorte und nur für eine ganz bestimmte Konfiguration der Pulverbeschichtungsvorrichtung gültig ist, jedoch beim Wechsel auf andere Pulversorten, bei Veränderung von Anlagenteilen, welche die Strömungsverhältnisse ändern, und bei Änderung der Fördergeschwindigkeit oder Taktgeschwindigkeit, mit welcher zu beschichtende Gegenstände an einer Sprühvorrichtung vorbei transportiert werden, nicht automatisch variabel ist und zur Neueinstellung eine Unterbrechung des automatischen Beschichtungsbetriebes erfordert. Ein weiterer Nachteil ist, daß solche manuelle Voreinstellungen sehr viel Erfahrung der Bedienungsperson benötigen, um bei sich wiederholenden gleichen Beschichtungsvorgängen gleiche Einstellungen zu erzielen. Ein weiterer Nachteil der bekannten mechanischen Luft-Teiler-Ventile ist, daß es sehr schwierig ist, sie mit der für die Praxis erforderlichen Präzision herzustellen. Die Verwendung von Druckreglern anstelle von solchen Luft-Teiler-Ventilen hat andererseits den Nachteil, daß der Volumenstrom der Luft und der Mengenstrom des Pulvers nicht linear zum Druck der Förderluft und der Zusatzluft sind.As the diverse state of the art shows, many development work in various directions has already attempted to achieve optimal operational settings with easy-to-implement measures. This has not yet been satisfactorily achieved. From the German Patent 1,266,685 is the basic principle of an injector for the pneumatic conveying of coating powder known. From the mentioned EP-B-0 412 289 is an electrostatic Powder coating device known, which contains in a conveying air line and in an additional air line per a pressure regulator and in a common compressed air supply line to the conveying air line and the additional air line, a display device for displaying the total air volume flow. When changing the conveying air flow rate by adjusting its pressure regulator to change the powder flow accordingly, the resulting change in the total air flow rate can be canceled by appropriate adjustment of the pressure regulator of the additional air line, taking into account the display on the display device again. Instead of manually, the pressure regulator can also be controlled automatically by a microcomputer. In a powder line leading from the injector to a spray device or container, a minimum amount of air is required to prevent powder deposits and flow pulsations in the powder line. The powder flow rate should be as constant as possible in the powder line or not fluctuate greatly, regardless of the amount of powder delivered per unit time. Therefore, more additional air must be added if the amount of conveying air to promote a small amount of powder per unit time (powder flow rate) must be reduced so much that in the powder line without the additional air would no longer be sufficient total air available. The additional air is introduced into the conveying air powder stream after a negative pressure region of the injector, in which the conveying air sucks in powder. According to a modified embodiment or in addition, however, additional air can be introduced into the negative pressure range to the strength of the Vacuum or vacuum, which is generated by the conveying air to vary. Thus, when reducing the conveying air volume flow of the additional air flow rate is increased, and vice versa. A similar device, each with a pressure regulator in a conveying air line and in an additional air line is also shown in FIG. 4 of US-A-3,625,404 known. From this same US script and from the DE-A-44 09 493 Air divider valves are also known, which have a throttle valve in the conveying air line and a throttle valve in the additional air line, which are mechanically coupled to each other and are manually or motor-adjustable, to the same extent as one throttle valve is opened, the other Throttling valve is closed further. In the air divider valve shown in Fig. 3 of said U.S. Patent, the valve bodies and their valve seats can be manually adjusted relative to one another to have a default of the amount by which one airflow should be greater or less than the other air flow. However, these mechanically coupled throttle valves have the disadvantage that said presetting of the difference between conveying air volume flow and additional air volume flow is valid only for a very specific type of powder and only for a very specific configuration of the powder coating device, but when changing to other types of powder, when changing system components which change the flow conditions and when the conveying speed or cycle speed with which articles to be coated are transported past a spraying device are not automatically variable and an interruption of the automatic restart is required Coating operation requires. Another disadvantage is that such manual presets require a great deal of operator experience to achieve the same settings for repetitive, same coating operations. Another disadvantage of the known mechanical divider valves is that it is very difficult to produce them with the precision required in practice. On the other hand, the use of pressure regulators instead of such air divider valves has the disadvantage that the volume flow of the air and the flow rate of the powder are not linear to the pressure of the conveying air and the additional air.

Durch die Erfindung soll die Aufgabe gelöst werden, jederzeit reproduzierbare Einstellungen der Förderluft und der Zusatzluft sowie der pro Zeiteinheit geförderten Pulvermenge zu erzielen, ohne daß Präzisionsprobleme bei der Herstellung auftreten und ohne besonders geschulte Bedienungspersonen zu benötigen, und außerdem ohne das Erfordernis von längeren Unterbrechungen des Beschichtungsbetriebes bei sich ändernden Beschichtungsbedingungen.The object of the invention is to achieve at all times reproducible settings of the conveying air and the additional air and the amount of powder delivered per unit time, without precision problems in the production occur and without requiring specially trained operators, and also without the need for longer interruptions of Coating operation with changing coating conditions.

Diese Aufgabe wird gemäß der Erfindung durch die Merkmale von Anspruch 1 gelöst.This object is achieved according to the invention by the features of claim 1.

Weitere Merkmale sind in den Unteransprüchen enthalten. Bei Verwendung eines elektrischen Schrittmotors sind zur Steuerung oder Regelung keine Istwert-Rückmeldungen an die Steuereinrichtung erforderlich, weil die Steuereinrichtung automatisch immer weiß, wieviel Schritte die Schrittmotoren in der einen oder anderen Drehrichtung ausgeführt haben. Die Steuereinrichtung ist eine vollständig elektronische Steuereinrichtung, vorzugsweise mit einem oder mehreren Mikroprozessoren.Further features are contained in the subclaims. When using an electric stepper motor, no actual value feedback to the control device is required for control or regulation because the control device always automatically knows how many steps the stepper motors have made in one or the other direction of rotation. The control device is a completely electronic Control device, preferably with one or more microprocessors.

An der Steuereinrichtung können Sollwerte für den Gesamtluft-Volumenstrom, die geförderte Pulvermenge pro Zeiteinheit und andere Werte eingegeben werden. Ferner kann die Steuereinrichtung automatisch von einem übergeordneten Leitstand oder Hauptrechner in Abhängigkeit von den zu beschichtenden Gegenständen gesteuert oder geregelt werden, beispielsweise bei einem Wechsel der Pulversorte, bei einem Wechsel der zu erzeugenden Beschichtungsdicke und/oder bei einem Wechsel der Taktgeschwindigkeit oder Fördergeschwindigkeit, mit welcher die zu beschichtenden Gegenstände an einer Sprühvorrichtung vorbei transportiert werden.Setpoints for the total air volume flow, the delivered powder quantity per unit time and other values can be entered at the control device. Furthermore, the control device can be automatically controlled or regulated by a superordinate control station or main computer depending on the objects to be coated, for example, when changing the type of powder, when changing the coating thickness to be generated and / or when changing the clock speed or conveying speed, with which the objects to be coated are transported past a spraying device.

Die Erfindung wird im folgenden mit Bezug auf die Zeichnung anhand einer bevorzugten Ausführungsform als Beispiel beschrieben. Die Zeichnung zeigt in der einzigen

Fig. 1
schematisch eine Pulverbeschichtungsvorrichtung nach der Erfindung.
The invention will be described below with reference to the drawing with reference to a preferred embodiment as an example. The drawing shows in the only one
Fig. 1
schematically a powder coating apparatus according to the invention.

Die in der Zeichnung dargestellte Pulverbeschichtungsvorrichtung nach der Erfindung enthält eine elektronische Steuereinrichtung 2, welche einen elektrischen Schrittmotor 4 zur Einstellung einer variablen Strömungsdrossel 6 in einer Förderluftleitung 8 und einen elektrischen Schrittmotor 14 zur variablen Einstellung einer einstellbaren Drossel 16 in einer Zusatzluftleitung 18 über elektrische Leitungen 10 bzw. 20 elektrisch steuert, in Abhängigkeit von einem Soll-Pulvermengenstrom (geförderte Pulvermenge pro Zeiteinheit) und in Abhängigkeit von einem Soll-Gesamtluft-Volumenstrom (pro Zeiteinheit geförderte Gesamtluft) bestehend aus Förderluft der Förderluftleitung 8 und Zusatzluft der Zusatzluftleitung 18. Es sind ein Taster 22 zur Erhöhung des Soll-Pulvermengenstromes, ein Taster 23 zur Reduzierung des Soll-Pulvermengenstromes, ein Taster 24 zur Erhöhung des Soll-Gesamtluft-Volumenstromes, und ein Taster 25 zur Reduzierung des Soll-Gesamtluft-Volumenstromes vorgesehen, welche jeweils manuell betätigbar sind. Gemäß einer abgewandelten Ausführungsform kann auch die elektronische Steuereinrichtung 2 eines oder mehrere Computerprogramme enthalten, welches die Sollwerte für den Pulvermengenstrom und den Gesamtluft-Volumentstrom in Abhängigkeit von den zu beschichtenden Gegenständen, deren Förder- oder Taktgeschwindigkeit, der zu erzeugenden Beschichtungsdicke, der zu verwendenden Pulverart (Korngröße, Kunststoff, Keramik) und/oder anderen Kriterien automatisch einstellt. Ein solches Computerprogramm oder solche Computerprogramme können statt in der Steuereinrichtung 2 in einer übergeordneten Steueranlage oder Leitstand 30 enthalten sein, welche mit der Steuereinrichtung 2 über einen Datenbus 32 in Datenaustausch steht.The powder coating apparatus according to the invention shown in the drawing comprises an electronic control device 2, which comprises an electric stepper motor 4 for setting a variable flow restrictor 6 in a conveying air line 8 and an electric stepper motor 14 for variably setting an adjustable throttle 16 in an additional air line 18 via electrical lines 10th or 20 electrically controls, in Dependent on a nominal powder flow rate (delivered amount of powder per unit of time) and depending on a nominal total air volume flow (per unit time delivered total air) consisting of conveying air of the conveying air line 8 and additional air of the additional air line 18. There is a button 22 to increase the target Powder flow rate, a button 23 for reducing the target powder flow rate, a button 24 to increase the target total air flow rate, and a button 25 for reducing the target total air flow rate provided, which are each manually operable. According to a modified embodiment, the electronic control device 2 may also contain one or more computer programs, which set the powder flow rate and the total air volume flow in dependence on the objects to be coated, their conveying or clock speed, the coating thickness to be generated, the type of powder to be used (Grain size, plastic, ceramics) and / or other criteria automatically sets. Such a computer program or such computer programs may be contained instead of in the control device 2 in a higher-level control system or control station 30, which communicates with the control device 2 via a data bus 32 in data exchange.

Die stromaufwärtigen Enden der Förderluftleitung 8 und der Zusatzluftleitung 18 sind über einen Druckregler 34 an eine gemeinsame Druckluftquelle 36 angeschlossen.The upstream ends of the conveying air line 8 and the additional air line 18 are connected via a pressure regulator 34 to a common compressed air source 36.

Die stromabwärtigen Enden der Förderluftleitung 8 und der Zusatzluftleitung 18 sind an einen Injektor 38 angeschlossen. Der Förderluftstrom der Förderluftleitung 8 strömt von einer Injektordüse 40 durch einen Unterdruckbereich 42, in welchem er einen Unterdruck erzeugt und dadurch aus einem Pulverbehälter 44 Beschichtungspulver 46 ansaugt, dann in einen Fangkanal 48 und von dort zusammen mit dem angesaugten Pulver durch eine Pulverleitung 50 zu einem weiteren Behälter oder entsprechend Fig. 1 zu einer Sprühvorrichtung 52. Die Sprühvorrichtung 52 ist vorzugsweise von der Art, welche Pulver elektrostatisch auflädt. Sie kann eine manuelle oder automatische Sprühpistole oder ein Rotationszerstäuber oder dergleichen sein. Sie sprüht das pneumatisch geförderte Pulver 46 auf zu beschichtende Gegenstände 54, welche von einer Transportvorrichtung 56 automatisch auf der Sprühseite der Sprühvorrichtung vorbei transportiert werden.The downstream ends of the conveying air line 8 and the additional air line 18 are connected to an injector 38. The conveying air flow of the conveying air line 8 flows from a Injector 40 through a negative pressure region 42 in which it generates a negative pressure and thereby sucks coating powder 46 from a powder container 44, then into a capture channel 48 and from there together with the sucked powder through a powder line 50 to another container or accordingly Fig. 1 to a spraying device 52. The spraying device 52 is preferably of the type which electrostatically charges powders. It may be a manual or automatic spray gun or a rotary atomizer or the like. It sprays the pneumatically conveyed powder 46 onto articles 54 to be coated, which are automatically transported by a transport device 56 past the spray side of the spraying device.

Eine Pulveransaugöffnung 58 des Injektors 38 mündet in den Unterdruckbereich 42. Der Behälter 44 kann statt unterhalb des Injektors 38 auch oberhalb des Injektors 38 angeordnet sein.A powder suction opening 58 of the injector 38 opens into the vacuum region 42. The container 44 can also be arranged above the injector 38 instead of underneath the injector 38.

Das stromabwärtige Ende der Zusatzluftleitung 18 ist an eine Zusatzluftöffnung 60 des Injektors 38 angeschlossen, von welcher die Zusatzluft in den Förderluft-Pulver-Strom des Fangkanales 48 strömt.The downstream end of the additional air line 18 is connected to an additional air opening 60 of the injector 38, from which the additional air flows into the conveying air-powder flow of the catching channel 48.

Zur Änderung der pro Zeiteinheit geförderten Pulvermenge (Pulvermengenstrom) oder zu seiner Konstanthaltung bei sich ändernder Pulverart wird der Förderluft-Volumenstrom der Förderluftleitung 8 von der Steuereinrichtung 2 über den Stellmotor 4 an der variabel einstellbaren Drossel 6 entsprechend eingestellt. Zum Ausgleich des sich dadurch ändernden Gesamtluftgehaltes im Luft-Pulverstrom wird der Zusatzluft-Volumenstrom der Zusatzluftleitung 18 durch Verstellung ihrer Drossel 16 mittels des Stellmotors 14 entsprechend ebenfalls verstellt.To change the amount of powder delivered per unit time (powder flow rate) or to keep constant with changing powder type of conveying air volume flow of the conveying air line 8 is set by the control device 2 via the servomotor 4 to the variably adjustable throttle 6 accordingly. To compensate for the thereby changing total air content in the air-powder flow of the Additional air flow rate of the additional air line 18 by adjusting its throttle 16 by means of the servomotor 14 also adjusted accordingly.

Anstelle der einzigen Zusatzluftleitung 18 können auch mehrere Zusatzluftleitungen vorgesehen sein, diese können in den Fangkanal 48 oder stromaufwärts oder stromabwärts davon in den Förderluft-Pulver-Strömungsweg münden.Instead of the single additional air line 18, a plurality of additional air lines may be provided, these may open into the catch channel 48 or upstream or downstream thereof in the conveying air-powder flow path.

Anstelle von elektrischen Schrittmotoren 4 und 14 als Stellmotoren, können auch andere Motoren verwendet werden, beispielsweise Servomotoren. In allen Fällen erfolgt die aufeinander abgestimmte Steuerung oder Regelung der Drosseln 6 und 16 durch ihre Motoren rein elektrisch durch die elektronische Steuereinrichtung 2. Die Verwendung von elektrischen Schrittmotoren anstelle von Hydraulikmotoren hat den Vorteil, daß die Steuereinrichtung 2 jederzeit "weiß", wie die zugehörige Drossel 6 bzw. 16 eingestellt ist, da sie automatisch weiß, wieviel Schritte der betreffende Schrittmotor in der einen oder anderen Drehrichtung von ihr gedreht wurde.Instead of electric stepper motors 4 and 14 as servo motors, other motors may be used, such as servomotors. In all cases, the coordinated control or regulation of the chokes 6 and 16 by their motors is purely electrical by the electronic control device 2. The use of electric stepper motors instead of hydraulic motors has the advantage that the control device 2 at any time "white", as the associated Throttle 6 or 16 is set, since it automatically knows how many steps of the respective stepper motor was rotated in one direction or the other of them.

Die Drosseln 6 und 16 können verstellbare Blenden oder verstellbare Ventile oder Hähne sein.The throttles 6 and 16 may be adjustable or adjustable valves or taps.

Ein Anzeigegerät 60 zeigt die Sollwerte und Istwerte des Förderluftvolumenstromes, des Zusatzluftvolumenstromes, des Gesamtvolumenstromes von Förderluft und Zusatzluft, und des Pulvermengenstromes an.A display device 60 displays the setpoint values and actual values of the delivery air volume flow, the additional air volume flow, the total volume flow of conveying air and additional air, and the powder flow rate.

Die geförderte Pulvermenge pro Zeiteinheit (Pulverrate) ist ungefähr proportional zur pro Zeiteinheit geförderten Förderluftmenge der Förderluftleitung 8. Deshalb braucht mit den Tasten 22 und 23 lediglich die Förderluft eingestellt zu werden, um eine gewünschte Pulvermenge einzustellen. Die Steuereinrichtung 2 stellt dann automatisch die Zusatzluftrate durch den Stellmotor 14 und die Drossel 16 so ein, daß trotz geänderter Förderluftrate der Gesamtluft-Volumenstrom (Gesamtluftrate) auf dem eingestellten Sollwert bleibt.The delivered amount of powder per unit time (powder rate) is approximately proportional to the per unit time promoted conveying air amount of the conveying air line 8. Therefore, only the conveying air needs to be adjusted with the keys 22 and 23 to set a desired amount of powder. The controller 2 then automatically adjusts the additional air rate by the servomotor 14 and the throttle 16 so that despite the changed delivery rate of the total air flow rate (total air rate) remains at the set value.

Die Förderluftrate und die Zusatzluftrate verändern sich, bei konstantem Luftdruck am Druckregler 34, nur dann proportional zu einer Veränderung des Strömungsquerschnittes ihrer Drosseln 6 und 16, wenn der Strömungswiderstand stromabwärts von ihnen sehr klein ist. Bei einer Vorrichtung der vorliegenden Art mit einem Injektor und einer Pulverleitung 50 ist jedoch der Strömungswiderstand so groß, daß die Förderluftrate und die Zusatzluftrate sich nicht linear zu Änderungen der Strömungsquerschnitte der Drosseln 6 und 16 ändern. Gemäß einer bevorzugten Ausführungsform der Erfindung ist in der Steuereinrichtung 2 die nicht-lineare Abhängigkeit für mindestens einen oder mehrere Strömungswiderstände (verschiedene Injektoren 38 und/oder Pulverleitungen 50) diagrammartig derart gespeichert, daß die Steuereinrichtung 2 die Drosseln 6 und 16 durch die Stellmotore 4 und 14 in Abhängigkeit von Sollwertvorgaben, z.B. an den Tastern 22, 23, 24 und 25, nicht-linear so ansteuert, daß sich eine zur Sollwertänderung lineare Veränderung der Förderluftrate und/oder der Zusatzluftrate ergibt.The delivery air rate and the additional air rate change, with constant air pressure at the pressure regulator 34, only proportional to a change in the flow cross section of their chokes 6 and 16, when the flow resistance downstream of them is very small. In a device of the present type with an injector and a powder line 50, however, the flow resistance is so great that the delivery air rate and the additional air rate do not change linearly to changes in the flow cross sections of the throttles 6 and 16. According to a preferred embodiment of the invention in the control device 2, the non-linear dependence for at least one or more flow resistances (various injectors 38 and / or powder lines 50) is stored diagrammatically such that the control device 2, the throttles 6 and 16 by the servo motors 4 and 14 in response to setpoint specifications, for example on the buttons 22, 23, 24 and 25, non-linearly so that there is a change in the setpoint change linearly the delivery air rate and / or the additional air rate.

Gemäß einer bevorzugten Ausführungsform der Erfindung ist die Sprühvorrichtung 50 eine manuelle Sprühpistole, an welcher die Taster 22 und 23, vorzugsweise auch die Taster 24 und 25 angeordnet und mit einem Finger manuelle betätigbar sind.According to a preferred embodiment of the invention, the spray device 50 is a manual spray gun, on which the buttons 22 and 23, preferably also the buttons 24 and 25 are arranged and manually operated with a finger.

Claims (3)

  1. Powder coating device having a feed air line (8) and at least one additional air line (18), which are connected to an injector (38) for the purpose of pneumatically feeding coating powder by means of feed air of the feed line and the additional air of the at least one additional air line, wherein at least one restrictor (6), the flow resistance of which is motor-adjustable, is arranged in both the feed air line (8) and in the at least one additional air line (18), and wherein an electronic control device (2) is provided for electrically adjusting the restrictors relative to one another as a function of a desired total air volumetric flow, comprising the feed air and the additional air, and as a function of a desired powder quantitative flow,
    characterized
    in that each restrictor (6, 16) is assigned a dedicated adjusting motor (4, 14), which can be driven by the control device (2), for setting its flow resistance, and in that for at least one embodiment of the flow path which follows the restrictors (6, 16) in the control device (2) a non-linear dependent relationship between a change in the cross section of flow of at least one of the restrictors (6, 16) and a resulting change in its air flow (8, 18) is stored in diagram form, such that the control device (2) drives the restrictors (6, 16) by means of the adjusting motors (4, 14) in non-linear fashion as a function of desired value presets, so that in the event of a change in the desired value of the associated air flow (8, 18) the result is a linear change in the associated quantitative air flow delivered per unit time.
  2. Powder coating device according to Claim 1,
    characterized in that the adjusting motors (4, 14) are electric stepper motors.
  3. Powder coating device according to Claim 1,
    characterized in that the adjusting motors (4, 14) are servomotors.
EP99927927A 1998-08-22 1999-06-09 Powder coating device Expired - Lifetime EP1115499B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19838269 1998-08-22
DE19838269A DE19838269A1 (en) 1998-08-22 1998-08-22 Powder coating arrangement has electronic controller that sets motors of all chokes relative to each other depending on demanded overall air volume flow and demanded powder flow
PCT/EP1999/003968 WO2000010727A1 (en) 1998-08-22 1999-06-09 Powder coating device

Publications (2)

Publication Number Publication Date
EP1115499A1 EP1115499A1 (en) 2001-07-18
EP1115499B1 true EP1115499B1 (en) 2008-03-05

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EP99927927A Expired - Lifetime EP1115499B1 (en) 1998-08-22 1999-06-09 Powder coating device

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JP (1) JP3421653B2 (en)
AT (1) ATE387963T1 (en)
CA (1) CA2341373C (en)
DE (2) DE19838269A1 (en)
ES (1) ES2303377T3 (en)
WO (1) WO2000010727A1 (en)

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DE20321762U1 (en) 1988-05-11 2009-08-27 H. Börger & Co. GmbH Device for conveying powdery material
DE10027873C1 (en) * 2000-06-06 2002-02-07 Festo Ag & Co Pneumatic pressure control device
US20100107562A1 (en) * 2000-06-28 2010-05-06 Weder Donald E Sheets of material having a first printed pattern on an upper surface thereof and a second printed pattern on a lower surface thereof
FR2824283B1 (en) * 2001-05-03 2004-10-29 Eisenmann France Sarl METHOD FOR REGULATING THE FLOW OF POWDER TRANSPORTED BY AN AIR FLOW, AND DEVICE FOR IMPLEMENTING IT
ATE375208T1 (en) * 2002-05-10 2007-10-15 Eisenmann Anlagenbau Gmbh & Co METHOD AND DEVICE FOR CONTROLLING THE AMOUNT OF POWDER IN A CARRIER GAS
DE102004052949A1 (en) * 2004-10-29 2006-05-04 Nordson Corp., Westlake Method and device for monitoring flow conditions in a wiring harness
US20060102075A1 (en) * 2004-11-18 2006-05-18 Saylor Austin A Fluid flow control
US7731456B2 (en) 2005-10-07 2010-06-08 Nordson Corporation Dense phase pump with open loop control
US20130287504A1 (en) * 2012-07-24 2013-10-31 Harry John Gatley Method and Apparatus Accelerate Gases Peripherally
US20160096693A1 (en) * 2013-03-29 2016-04-07 Matsui Mfg. Co., Ltd. Material conveyance device and material conveyance method

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CH436120A (en) 1966-06-28 1967-05-15 Gema Ag Pneumatic conveying device with adjustable conveying capacity
US3625404A (en) 1969-06-02 1971-12-07 Ransburg Electro Coating Corp Apparatus and method for dispensing particulate material
DE8915968U1 (en) * 1989-08-11 1992-12-17 Gema Volstatic Ag, St. Gallen Electrostatic powder coating equipment
JPH06246196A (en) * 1993-02-22 1994-09-06 I T M Kk Powder supplying device, electrostatic powder coating device and powder flow rate measuring instrument
CH688989A5 (en) 1993-03-26 1998-07-15 Ribnitz Peter Apparatus for conveying powder
US5351903A (en) * 1993-04-06 1994-10-04 Russell Mazakas Electrostatic powder paint gun with trigger control variable voltage
EP0634713B1 (en) * 1993-07-15 1999-12-29 Nordson Corporation Improvements in and relating to air regulation control
DE4325044C2 (en) * 1993-07-26 2002-07-18 Itw Gema Ag Powder conveying device, in particular for coating powder
DE59610361D1 (en) * 1995-09-18 2003-05-28 Elpatronic Ag Bergdietikon Process for conveying a powdery material by means of an injector

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DE59914678D1 (en) 2008-04-17
WO2000010727A1 (en) 2000-03-02
CA2341373C (en) 2005-02-01
ATE387963T1 (en) 2008-03-15
CA2341373A1 (en) 2000-03-02
JP2002523217A (en) 2002-07-30
DE19838269A1 (en) 2000-02-24
EP1115499A1 (en) 2001-07-18
ES2303377T3 (en) 2008-08-01
US6443670B1 (en) 2002-09-03
JP3421653B2 (en) 2003-06-30

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