EP0676242A2 - Verfahren und Vorrichtung zum elektrostatischen Sprühbeschichten - Google Patents

Verfahren und Vorrichtung zum elektrostatischen Sprühbeschichten Download PDF

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Publication number
EP0676242A2
EP0676242A2 EP95410023A EP95410023A EP0676242A2 EP 0676242 A2 EP0676242 A2 EP 0676242A2 EP 95410023 A EP95410023 A EP 95410023A EP 95410023 A EP95410023 A EP 95410023A EP 0676242 A2 EP0676242 A2 EP 0676242A2
Authority
EP
European Patent Office
Prior art keywords
coating
trigger
voltage
electrode
value
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP95410023A
Other languages
English (en)
French (fr)
Other versions
EP0676242A3 (de
Inventor
Gregg Matschke
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sames Kremlin SAS
Original Assignee
Sames SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sames SA filed Critical Sames SA
Publication of EP0676242A2 publication Critical patent/EP0676242A2/de
Publication of EP0676242A3 publication Critical patent/EP0676242A3/de
Withdrawn legal-status Critical Current

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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
    • B05B12/00—Arrangements for controlling delivery; Arrangements for controlling the spray area
    • 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
    • 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
    • B05B5/0531—Power generators

Definitions

  • the invention relates to a method and a device for electrostatic spraying of liquid or pulverulent coating product and more particularly relates to an improvement of the electrostatic charging means of the coating product making it possible to obtain a coating of optimum and constant thickness whatever the shape of the object to be coated.
  • the invention also makes it possible to improve the deposition yield compared to what is obtained with conventional devices, thereby saving coating material.
  • the coating product is electrostatically charged by one or more electrodes in order to follow the lines of electrostatic field between the projection device and the object to be coated.
  • Charging can be carried out by contact of the product with the electrode or by Corona discharge from the electrode.
  • the intensity of the electric force undergone by each particle of coating product depends on the charge carried by the particle and on the ambient electrostatic field.
  • the latter is a function, among other things, of the geometric configuration of the object to be coated. Indeed, if a sharp edge of the object is placed opposite the projection device, the field lines tend to all close on this edge. The particles being guided by the electrostatic field, this leads to an accumulation of product at this location while the flat surfaces in the vicinity of the edge are insufficiently coated.
  • the electrostatic field lines tend to close on the edges of the cavity, which tends to prevent the coating product from entering the bottom of the cavity in question.
  • the invention solves all of these problems.
  • It relates to a method for electrostatic projection of a coating product, characterized in that the value of the supply voltage of at least one electrostatic charging electrode is controlled during the coating of an object as a function of the geometric configuration of said object. .
  • the process of the invention it is possible to reduce both the charge of each particle and the intensity of the electrostatic field between the device and the object to be coated at will, and in particular when coating sharp edges or cavities.
  • This makes it possible to reduce the intensity of the electric force undergone by each particle of product and makes it possible to use more efficiently the aerodynamic forces created by the driving air.
  • it is then possible to precisely direct the jet of coating product sprayed mainly with the entrainment air.
  • the invention also relates to a device for electrostatic projection of a coating product comprising at least one charging electrode, characterized in that it comprises means for controlling the value of the supply voltage of said electrode as a function of the geometric configuration of the object to be coated.
  • the invention finally relates to a manual device for electrostatic projection of coating product comprising at least one charging electrode and provided with an actuating trigger connected to means for supplying coating product, characterized in that it comprises a means for adjusting the supply voltage of said electrode sensitive to the position of said trigger.
  • the powder spray gun 1 shown in Figure 1 is, except for the high voltage control system, built according to the rules of the art. It comprises a barrel 2 and a handle 3 intended to be taken in hand by an operator. It is supplied with air-powder mixture through a conduit 4 in which is housed an electric cable 5 supplying the high voltage unit 6 embedded in the barrel 2. The high voltage unit 6 is electrically connected to an electrode load 7 housed in the spray nozzle 8 located at the end of the duct 4.
  • a trigger 10 intended to be actuated by the operator.
  • This trigger carries a first extension 11 capable of controlling a first switch 12 connected to the cable 5.
  • the position of the switch is detected in the general control system of the device and the pneumatic powder drive system and the supply in high unit voltage 6 are controlled from this information. The position of the trigger therefore makes it possible to activate or not the projector.
  • the trigger has a second extension 13 capable of controlling a second switch 14.
  • the closing of the switches 12 and 14 takes place in positions different from the trigger 10.
  • the switch 12 is activated for a low movement of the trigger while the switches 12 and 14 are activated for maximum movement of the trigger.
  • Two springs 15 and 16 respectively ensure the deactivation of the switches 12 and 14.
  • the stiffness constants of the springs 15 and 16 may possibly be different, for example the stiffness constant of the spring 16 may be greater than that of the spring 15.
  • the spring 15 is constituted by the electrical contact blade of the switch 12.
  • the switch 12 is controlled for a low pressure of the operator's finger while the switch 14 is controlled for a higher pressure operator's finger.
  • the switches 11 and 13 are mounted on the supply line of the high voltage unit, they can be connected to a step-up transformer 9.
  • FIG. 2 On the block diagram of Figure 2, there is shown a DC voltage arrival V1 and the voltage V2 which is delivered to the primary of the transformer 9.
  • a voltage divider bridge is made by two resistors Ra and Rb. At rest, the switches 12 and 14 are closed, V2 is therefore zero. The power dissipated in the resistance Ra is low and does not risk damaging the equipment.
  • the voltage V2 becomes equal to V1 minus the voltage across the resistance Ra. This corresponds to 100% of the value of the voltage which can be supplied to the transformer 9.
  • the switch 14 When the switch 14 is not activated, that is to say when it is closed, the voltage V2 drops because the bridge voltage divider is activated: Part of the electric current is dissipated in the resistor Rb.
  • Ra and Rb such that the ratio Rb / (Ra + Rb) is equal to the desired ratio between the voltages desired at the electrode, for example 60%.
  • the value of the maximum voltage is set by the operator at a projector control panel, not shown, which controls the voltage source to which the cable 5 is connected and which delivers the voltage V1.
  • FIG. 3a represents the position of the trigger at rest, that is to say without operator pressure: no product is supplied to the gun 1 and no high voltage is delivered by the unit 6.
  • FIG. 3b represents the position of the trigger when the switch 12 is open and the switch 14 is closed: the air-powder mixture is supplied to the gun by the conduit 4 and the high voltage at the electrode 7 is equal to one determined fraction, for example 60%, of the value that is set by the operator at the general gun control console.
  • Figure 3c shows the position of the trigger when switch 12 and switch 14 are open: the air-powder mixture is supplied to the gun via line 4 and the high voltage at electrode 7 is equal to 100% of that set by the operator at the general gun control console.
  • the operator When the operator coats parts having large flat surfaces, he exerts strong pressure on the trigger 10 in order to move the latter of its maximum stroke. In this case, the two switches 12 and 14 are activated, the position of the trigger is that shown in FIG. 3c and the voltage at the electrode is maximum.
  • the coating product is fully charged and completely undergoes the electrostatic effect. The deposition yield is satisfactory due to the use of the electrostatic effect.
  • the coating product is uniformly distributed over the surface to be coated.
  • the coating product consumed by the device is permanently deposited so optimal on the object, namely without accumulation on the edges but up to the bottom of the cavities, which avoids overconsumption of product.
  • the known advantages of coating by the electrostatic route in particular in terms of the deposition yield, are preserved.
  • the trigger 10 has been shown as capable of allowing the supply of the electrode 7 with two values, but the number of values is not limited to two. It suffices to provide a number of switches equivalent to the switches 12 and 14 and to house them in the projector opposite appropriate extensions of the trigger. In the case of three supply values for electrode 7, it will be advantageous to provide a lower voltage for electrode 7 for coating the cavities than for coating the edges.
  • the actuation trigger may be progressive operation, that is to say continuous over an operating range.
  • the extension 13 of the trigger is mechanically connected to the cursor 50 of a variable potentiometer 51.
  • the other elements identical to those of FIG. 2 have the same references, the operation is similar.
  • the potential V2 depends on the position of the cursor 50 on the potentiometer 51 because the ratio Rb / (Ra + Rb) previously mentioned depends of the active fraction of potentiometer 51. All the values included in a defined operating range can then be chosen by the operator, which will be useful in the case of particularly complex parts. In the latter case, it is possible to arrange all the members for selecting the value of the high voltage applied to the electrode 7 on the gun 1, possibly including a display: it is no longer necessary to provide a console separate order.
  • the invention also applies to the case of a sprayer of liquid coating product.
  • the same multi-level or progressive operation trigger structures as described above can be used.
  • FIG. 5 The installation of Figure 5 is, except for the high voltage control system, built according to the rules of the art. It comprises an automatic coating machine 101 carrying a projector 102 of liquid paint, for example rotary, housed at the end of an arm 103 movable vertically.
  • the spray bowl 104 can be brought to high voltage by any known means and thus constitutes a charging electrode.
  • a sensor, for example an optical sensor, 110 detects the shape of objects 111, such as for example bodies of a washing machine, transported by a conveyor opposite the projector 102.
  • the objects 111 may have planar surfaces 111a, edges 111b and cavities 111c.
  • the sensor 110 is connected to a control unit 112, which controls the machine 101 and a high voltage generator 113, in particular as a function of the signal received from the sensor 110.
  • the unit 112 is provided with a memory in which the geometric configurations of the objects likely to be treated in the installation.
  • the unit 112 recognizes the objects and adapts the coating parameters, such as the positioning of the arm 103, the flow of paint supplied to the projector 103 and the value of the high voltage delivered by the generator. 113, accordingly.
  • the value of the high voltage varies during the coating of the body 111. Thus, it is maximum when coating a flat surface 111a and it is reduced to a fraction of the maximum voltage when coating an edge 111b or to inside a cavity 111c. The accumulation of paint on the edge 111b is thus avoided, while it is possible to properly coat the interior of the hollow body 111.

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  • Application Of Or Painting With Fluid Materials (AREA)
  • Electrostatic Spraying Apparatus (AREA)
EP95410023A 1994-03-31 1995-03-30 Verfahren und Vorrichtung zum elektrostatischen Sprühbeschichten. Withdrawn EP0676242A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US22067694A 1994-03-31 1994-03-31
US220676 1994-03-31

Publications (2)

Publication Number Publication Date
EP0676242A2 true EP0676242A2 (de) 1995-10-11
EP0676242A3 EP0676242A3 (de) 1996-06-05

Family

ID=22824506

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95410023A Withdrawn EP0676242A3 (de) 1994-03-31 1995-03-30 Verfahren und Vorrichtung zum elektrostatischen Sprühbeschichten.

Country Status (2)

Country Link
US (1) US5503880A (de)
EP (1) EP0676242A3 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014172203A1 (en) * 2013-04-17 2014-10-23 Finishing Brands Holdings Inc. Electrostatic spray tool system

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Publication number Priority date Publication date Assignee Title
JP3354038B2 (ja) * 1995-09-29 2002-12-09 本田技研工業株式会社 静電塗装方法
US5678770A (en) * 1996-01-03 1997-10-21 Shah; Amal B. Powder coating spray gun with resettable voltage multiplier
US5817373A (en) * 1996-12-12 1998-10-06 Micron Display Technology, Inc. Dry dispense of particles for microstructure fabrication
US6780491B1 (en) 1996-12-12 2004-08-24 Micron Technology, Inc. Microstructures including hydrophilic particles
DE19838275A1 (de) * 1998-08-22 2000-02-24 Itw Gema Ag Manuelle Sprühbeschichtungspistole
US6460787B1 (en) * 1998-10-22 2002-10-08 Nordson Corporation Modular fluid spray gun
USD441833S1 (en) 1998-11-26 2001-05-08 Itw Gema Ag Spray coating device
US6758423B1 (en) * 1999-09-17 2004-07-06 Nordson Corporation Spray gun with data device and method of control
USD447791S1 (en) 2000-12-14 2001-09-11 The Easthill Group, Inc. Spray gun
GB2377191B (en) * 2001-07-06 2003-09-10 Reckitt Benckiser Spraying device
US6676049B2 (en) 2001-11-16 2004-01-13 Efc Systems, Inc. Bell cup powder spray applicator
WO2005018825A1 (en) * 2003-08-18 2005-03-03 Nordson Corporation Wireless operator interface for material application system
BR112012023070A2 (pt) * 2010-03-18 2019-09-24 Axia Acquisition Corp ajuste de fluxo de bomba em ferramenta.
CA140534S (en) * 2010-12-30 2012-12-03 Illinois Tool Works Powder spray gun

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FR1360743A (fr) * 1963-02-19 1964-05-15 Sames Mach Electrostat Perfectionnements aux pistolets pour pulvérisation et projection électrostatique de peinture
CH505653A (de) * 1968-04-26 1971-04-15 Mueller Ernst Fa Verfahren zum Beschichten von Werkstücken mit Pulver und Vorrichtung zur Durchführung des Verfahrens
US4441656A (en) * 1982-01-29 1984-04-10 J. Wagner Ag Electrostatic disabling switch for electrostatic spray guns
US4437614A (en) * 1982-09-28 1984-03-20 Binks Manufacturing Company Electrostatic air atomization spray coating system
DE3507965C1 (de) * 1985-03-06 1986-04-03 Ransburg-Gema AG, St.Gallen Elektrostatische Spruehpistole fuer Beschichtungsmaterial
US4774102A (en) * 1986-06-09 1988-09-27 Morton Thiokol, Inc. Method of electrostatic powder spray coating
US4971257A (en) * 1989-11-27 1990-11-20 Marc Birge Electrostatic aerosol spray can assembly
US5080289A (en) * 1990-05-25 1992-01-14 Graco Inc. Spraying voltage control with hall effect switches and magnet
US5238709A (en) * 1991-04-26 1993-08-24 W. R. Grace & Co.-Conn. Electrostatic spray coating method
JPH0550015A (ja) * 1991-08-09 1993-03-02 Kobe Steel Ltd 塗装方法
US5351903A (en) * 1993-04-06 1994-10-04 Russell Mazakas Electrostatic powder paint gun with trigger control variable voltage

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014172203A1 (en) * 2013-04-17 2014-10-23 Finishing Brands Holdings Inc. Electrostatic spray tool system
US9399232B2 (en) 2013-04-17 2016-07-26 Carlisle Fluid Technologies, Inc. Electrostatic spray tool system

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Publication number Publication date
EP0676242A3 (de) 1996-06-05
US5503880A (en) 1996-04-02

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