EP0154416B1 - Pulversprühpistole - Google Patents

Pulversprühpistole Download PDF

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Publication number
EP0154416B1
EP0154416B1 EP19850300820 EP85300820A EP0154416B1 EP 0154416 B1 EP0154416 B1 EP 0154416B1 EP 19850300820 EP19850300820 EP 19850300820 EP 85300820 A EP85300820 A EP 85300820A EP 0154416 B1 EP0154416 B1 EP 0154416B1
Authority
EP
European Patent Office
Prior art keywords
powder
transport tube
spray gun
tube
electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19850300820
Other languages
English (en)
French (fr)
Other versions
EP0154416A1 (de
Inventor
Thomas E. Hollstein
James J. Turner
Douglas C. Mulder
David E. O'ryan
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.)
Nordson Corp
Original Assignee
Nordson Corp
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 Nordson Corp filed Critical Nordson Corp
Publication of EP0154416A1 publication Critical patent/EP0154416A1/de
Application granted granted Critical
Publication of EP0154416B1 publication Critical patent/EP0154416B1/de
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
    • B05B5/03—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying
    • B05B5/032—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying for spraying particulate materials

Definitions

  • This invention relates to an electrostatic powder spray gun.
  • Electrostatic powder spray systems operate on the principle of transporting a finely divided powder, generally of the order of 150 mesh, to a spray gun or spray head while the powder is entrained in an air or gaseous stream.
  • the air entrained powder is transferred from the nozzle of the gun to a target article or substrate by an electrostatic charge applied to the powder and an effectively opposite charge on the substrate.
  • the powder is generally heated and melted so as to adhere the powder to the substrate as a film when the molten powder subsequently cools.
  • a characteristic of nearly all electrostatic powder spray applications is that less than half of all the sprayed powder adheres to the target article or substrate.
  • the over-sprayed powder thus must generally be collected, cleaned, and recycled in order for a powder spray system to operate efficiently and economically.
  • the cost of collecting and recycling the powder is substantially greater than the cost of initially applying the powder. Consequently, it is very important to the economy of powder spray systems that as high a percentage as possible of the initial sprayed powder be adhered to the target article or substrate so that a minimum of the sprayed powder need be recycled or lost if the powder is not to be recycled.
  • the efficiency or percentage of sprayed powder which adheres to the target is a function of many variables, including the size and density of the sprayed powder, the velocity of the air stream in which the powder is ejected from the spray gun, the charge applied to the powder, and the configuration of the powder spray pattern.
  • an electrostatic spray gun for powder coating having a resistor contained within a housing a powder transport tube mounted also within the housing and a nozzle fixed to the forward end of the tube.
  • an electrostatic spray gun having a resistor contained within a housing, a coating material transport tube with a nozzle fixed to its forward end and an electrode which is connected to the resistor and extends forwardly of the housing.
  • the position of the electrode is adjustable with respect to the nozzle to ensure that it is always outside the jet of coating material emitted from the nozzle.
  • Such provides a powder spray gun which can rapidly and inexpensively be converted from the spraying of one powder to another or from one spray pattern to another, enables the gun, the volume and velocity of powder transport air readily to be varied so as to optimize the powder ejection rate from the gun and provides a powder spray gun which has an even flow of powder from othe gun and an even distribution of powder within the pattern emitted from the gun.
  • the straight powder transport tube is replaceable, and may be secured within the housing of the gun by an infinitely adjustable locking element the tube with its attached nozzle, may be easily adjusted in position or replaced with a different tube of a different inside diameter.
  • the transport velocity of powder emitted from the gun may be easily varied and optimized for a particular discharge rate and density of powder.
  • the adjustable securement of the powder transport tube relative to the gun housing is such that the tube discharge end may be varied in location relative to a powder charging electrode of the gun so as to optimize the charge applied to powder ejected from the end of the tube.
  • the first of these two characteristics i.e. the powder velocity at exit from the gun is a function of the internal diameter of the tube through which the powder is transported and whether that diameter is straight or curved and whether it varies from one end of the gun to the other.
  • that tube should be straight and should be of a fixed diameter from one end to the other of the gun.
  • discharge end of the tube or the nozzle which may be attached to the discharge end of that tube, should be adjustable relative to an electrode operable to apply a charge to the powder emitted from the nozzle of that tube.
  • the powder transport tube is preferably easily replaceable with a different tube of a different internal diameter so as to enable powders of varying characteristics to be sprayed from the gun with an optimal transport velocity as the powder is emitted from the gun.
  • a discharge nozzle or a powder deflector may alternatively be mounted in the discharge end of the powder transport tube.
  • the housing of the gun preferably (includes a bore or tube within which there is mounted the electrical resistor.
  • This electrical resistor is connected at one end to an electrical cable and is connected at the other end to the powder charging electrode.
  • This electrode is mounted externally of the nozzle or discharge end of the powder transport tube so that the transport tube may be adjusted relative to the electrode and thereby the charge applied to the electrode may be optimized for any particular spray pattern emitted from the gun.
  • this gun has the advantage of enabling the nozzle of the gun to be easily adjustably positioned relative to the electrode of the gun.
  • the powder spray gun 10 shown in Figure 1 is intended for use as a part of a powder spray system, such as that disclosed in US-A-4,245,551.
  • air entrained powder is supplied to a powder spray gun through a supply hose while simultaneously, a very high voltage electrical charge is supplied to the gun from a source of electrical power.
  • the electrostatic spray gun is operative to dispense the air entrained powder in a predetermined pattern while simultaneously applying a charge to the powder.
  • the electrical charge then is operative to transport the powder from the nozzle of the gun to a target article or substrate which is of an opposite charge from that applied to the powder by the gun.
  • a negative charge is applied to the powder by the electrostatic spray gun and the target article or substrate to which the powder is to be applied is grounded so that the powder is attracted to the article and adheres thereto, as a consequence of the charge on the powder.
  • the powder spray gun 10 is shown having a housing 11 upon which there is mounted a nozzle 12 and an electrode support 13.
  • the housing 11 comprises a pair of spaced mounting blocks 14 and 15 between which there are supported a pair of tubes 16 and 17.
  • the uppermost one of these tubes is a resistor support tube 16 and the lowermost tube is a powder transport tube 17.
  • Components 14,16 and 17 are electrically non-conductive, while component 15 is electrically conductive to provide conductance to ground.
  • the forwardmost one of the mounting blocks 14 has a lower threaded through-bore 20 therein which may be threaded and an upper blind recess 21.
  • the blind recess 21 is threaded as indicated at 22. Intersecting this blind recess 21 there is an angled threaded bore 23.
  • the electrode support 13 is threaded into the bore 23 and the forward threaded end 24 of the resistor support tube 16 is threaded into the threaded section 22 of the recess 21.
  • the threaded forward end 25 of the powder transport tube 17 is threaded into and through the threaded bore 20 of the mounting block 14 so that the forwardmost end 25 of the powder transport tube 17 extends forwardly beyond the front face 26 of the mounting block 14.
  • the powder transport tube 17 is locked in an adjusted position relative to the mounting block 14 by a jam nut 27 threaded over the rearwardmost threaded portion of the threaded forward end 25 of the powder transport tube 17.
  • the rear mounting block 15 is provided with a pair of through-bores 30, 31.
  • the powder transport tube 17 extends through the lowermost one of these through-bores.
  • the uppermost bore 31 is threaded for reception of the threaded rear end of the resistor support tube 16 and for reception of the threaded forward end 33 of a cable adaptor 34.
  • the rear end of the cable adaptor 34 is also threaded for connection to a conventional electrical shielded cable (not shown).
  • transverse bore 36 Extending transversely through the rear mounting block 13 there is a transverse bore 36.
  • This transverse bore 36 is intersected by a threaded bore 37 within which there is a set screw 38.
  • the transverse bore 36 enables the rear mounting block 15 and thus the gun 10 to be secured to a mounting rod and fixed thereon by the set screw 38 as is conventional in this art.
  • this resistor 40 is connected via an electrically conductive spring 41 to an insulated electrical cable 42 contained internally of a conventional shielded cable (not shown) adapted to be connected to the cable adapter 34.
  • the forward end of the resistor 40 is electrically connected to a smaller resistor 44 contained internally of the electrically non-conductive, casing of the electrode support 13.
  • This small resistor 44 is connected via a conventional connector 45 to the forward end of the large resistor 40.
  • the small resistor 44 is attached to the powder charging electrode 46 which extends forwardly beyond the forward end of the casing of electrode support 13.
  • a source of air entrained powder such as a conventional powder feed hopper
  • a source of air entrained powder such as a conventional powder feed hopper
  • air entrained powder may be transported through the tube and ejected from an orifice 49 in the forward end of the nozzle 12.
  • the nozzle 12 is a conventional slotted nozzle, however, any type of powder spray nozzle may be utilized.
  • the powder ejected from the nozzle orifice 49 is electrically charged during the course of passage through an electrostatic field created by the electrode 46. That powder then adheres to an effectively oppositely charged substrate (not shown) toward which the powder is ejected.
  • the velocity imparted to the powder ejected from the nozzle of the gun is not so great that the powder sprays over and past or bounces off of the substrate toward which it is ejected.
  • the powder has sufficient velocity that it does not fall out of the airstream and collect either in the powder transport tube 17 or in the vicinity of the nozzle orifice 49.
  • the nozzle orifice 49 be positioned relative to the electrode 46 so that the charge applied to the powder emerging from the nozzle is optimized. It has been found that if the relative position between the nozzle orifice and the electrode 46 is infinitely adjustable, the nozzle orifice may be positioned so as to optimize the charge applied to the powder by the electrode 46.
  • the gun 10 described hereinabove may be constructed so as to facilitate longitudinal adjustment of the powder transport tube 17 relative to the supporting block 14, and consequently relative to the electrode 46 mounted within that block 14.
  • This gun also facilitates replacement of the powder transport tube 17 so that tubes of varying inside diameters may be utilized and interchanged one with the other.
  • all that is required to replace a tube 17 is to remove the nozzle 12 from the end of the tube, unthread, and then pull the tube 17 rearwardly until the tube is withdrawn from the forward and rear mounting block 14, 15.
  • the jam nut 27 may then be removed and applied to another replacement tube of differing inside diameter.
  • the replacement tube may then be inserted through the bore 30 in the rear mounting block and threaded into the bore 20 until the jam nut 27 engages the rearward face of the mounting block 14.
  • the nozzle 12 may then be threaded onto the forward end of the powder transport tube and the nut 27 adjusted until the orifice 49 of the nozzle 12 is properly positioned relative to the electrode 46.
  • an insert tube (not shown) may be inserted into the tube 17 so as to effectively change the inside diameter of the tube 17 without replacing it in the mounting blocks 14, 15.
  • Such an insert tube would be the same length as the transport tube 17 (or longer to facilitate connection to the powder hose) and would have an outside diameter approximately the same diameter as the inside diameter of the transport tube 17. It would have an inside diameter of the same dimension from one end to the other but the inside diameter would, of course, be less than the inside diameter of the tube 17 within which such an insert tube would be mounted.
  • Such an insert tube would also be made from electrically non-conductive material.
  • a spray gun 110 which is an embodiment of the spray gun 10 shown in Figure 1.
  • those components of the gun which are identical to the components of the embodiment illustrated in Figure 1 have been given the same numerical designation as is used in Figure 1, except that in this embodiment the numeral is followed by the letter "a”.
  • the embodiment illustrated in Figures 2 and 3 is identical to the embodiment illustrated in Figure 1, except that it differs in the configuration of the powder transport tube nozzle and in the manner in which the powder transport tube 117 is, adjusted relative to the forward mounting block 114.
  • This embodiment also differs from the embodiment illustrated in Figure 1 in that there is a deflector mounting insert 118 located within the forward end of the powder transport tube 117 and a conical powder deflector 119 extending forward of the gun outlet orifice.
  • the powder transport tube is adjustable relative to the mounting block 114 as a consequence of the tube 117 being slideable within a smooth bore 120 of the mounting block 114.
  • This bore 120 is intersected by a threaded bore 121 within which a set screw 122 is mounted.
  • the powder transport tube 117 is secured or locked in an adjusted position by tightening the set screw 122. This results in the discharge end of the powder transport tube being secured in an adjusted position relative to the electrode 46a.
  • the deflector mounting insert 118 is generally shaped as a cylinder having a cone shaped rear end 125 and four flutes 126 extending radially from the cylindrical centre section. The outer edges of these flutes 126 engage the inside wall 127 of the powder transport tube 117 so as to define four air flow passages 128 between the flutes 126.
  • the forward end of the deflector mounting insert 118 is tapered as indicated at 130. Additionally, the forward end of the insert is provided with a blind recess 131 within which the rearward cylindrical end 132 of the deflector 119 is mounted.
  • the deflector is fixedly secured to the powder transport tube 117 by means of a pin 133 which extends transversely through the powder transport tube 117, the insert 118 and the cylindrical end 132 of the deflector 119.
  • a pin 133 which extends transversely through the powder transport tube 117, the insert 118 and the cylindrical end 132 of the deflector 119.
  • adjustment of the powder transport tube 117 relative to the mounting block 114 effects adjustment of the deflector 119 relative to the electrode 46a. It has been found that this adjustability of the deflector 119 relative to the electrode 46a, as well as the positioning of the electrode 46a behind rather than forwardly or internally of the deflector, optimize the electrical charge which may be applied to powder by the electrode. Additionally it has been found that if the deflector has a relatively long length dimension L of 2 inches to 5 inches, for example, and a relatively large diameter dimension D of 2 inches to 5 inches, for example, the powder pattern generated by the gun 110 may be optimized.
  • air entrained powder is passed through the powder transport tube 117 of the gun 110 and the four passages 128 surrounding the deflector mounting insert 118 in the discharge end of the tube.
  • the powder picks up an electrical charge from the electrode 46a. It then engages and passes over the conically shaped deflector 119 so as to have a generally conical shaped pattern imparted to the powder. It has been found that dividing the flow of air entrained powder as it emerges from the gun via the deflector mounting insert 118, has the effect of stabilizing the powder pattern ejected from the gun. In the absence of the insert 118, the powder has a tendency to swirl as it emerges from the gun.
  • the guns 10 and 110 have been described as having the electrode 46 and 46a mounted external to and independently of the nozzle 12 or deflector 119 so as to enable the nozzle or deflector to be adjusted relative to the electrode.

Landscapes

  • Electrostatic Spraying Apparatus (AREA)

Claims (11)

1. Elektrostatische Sprühpistole zum Versprühen von teilchenförmigen Feststoffpulvermaterialien, umfassend ein elektrisch nicht leitendes Gehäuse, einen innerhalb des Gehäuses befindlichen und mit einer von dem Gehäuse nach vorne verlaufenden Elektrode elektrisch verbundenen Widerstand, ein gerades, elektrisch nicht leitendes Pulvertransportrohr, das in das Gehäuse eingebaut und an seinem hinteren Ende an eine Quelle von einem Luftstrom mitgenommenen Pulvers angeschlossen werden kann, und eine Vorrichtung zum mustermäßigen Versprühen des Pulvers, in einem Konus, die am Ausgang des Pulvertransportrohrs befestigt ist, dadurch gekennzeichnet, daß das Pulvertransportrohr abnehmbar in dem Gehäuse befestigt ist sowie dadurch, daß eine Verriegelungsvorrichtung (27) vorgesehen ist, um den Ausgang des Pulvertransportrohrs in einer Reihe von Einstellungspositionen in Bezug auf das Gehäuse und die Elektrode abnehmbar zu befestigen.
2. Elektrostatische Sprühpistole nach Anspruch 1, worin das elektrisch nicht leitende Gehäuse (11) ein Paar in einem Abstand voneinander angeordnete Montageblöcke (14, 15) umfaßt, wobei der eine der Montageblöcke nach vorne von dem anderen beabstandet ist und eine sich von diesem nach vorne erstreckende Elektrode (46) aufweist.
3. Elektrostatische Sprühpistole nach Anspruch 2, worin das Pulvertransportrohr (17) zwischen den Montageblöcken (14, 15) verläuft und abnehmbar in Bezug auf diese montiert ist, wobei die Verriegelungsvorrichtung (27) das Pulvertransportrohr relativ zu dem vordersten Montageblock (14) abnehmbar befestigt.
4. Elektrostatische Sprühpistole nach einem der Ansprüche 2 oder 3, worin ein zweites Rohr (16) zwischen den Montageblöcken (14,15) parallel zu dem Pulvertransportrohr (17) verläuft, wobei der Widerstand (40) innerhalb des zweiten Rohres eingebaut ist.
5. Pulversprühpistole nach einem der Ansprüche 2 bis 4, worin sich in dem hinteren der beiden Montageblöcke (15) ein elektrischer Kabeladapter (34) befindet, wobei der elektrische Kabeladapter ein elektrisch geschütztes Kabel aufnehmen kann.
6. Pulversprühpistole nach einem der vorhergehenden Ansprüche, worin die Vorrichtung zum mustermäßigen Versprühen des Pulvers einen Deflektormontageeinsatz (118) aufweist, der im Innern des vorderen Endes des Pulvertransportrohrs (117) befestigt ist und worin ein allgemein konisch geformter Deflektor (119) auf dem Einsatz montiert ist und sich von diesem nach vorne erstreckt.
7. Pulversprühpistole nach Anspruch 6, worin der Deflektor (119) von der Elektrode (46a) nach vorne verläuft.
8. Pulversprühpistole nach einem der Ansprüche 6 oder 7, worin der Deflektor (119) eine im Vergleich zum Innendurchmesser (D') des Pulvertransportrohrs (117) relativ große Länge (L) und einen relativ großen Durchmesser (D) aufweist.
9. Pulversprühpistole nach Anspruch 8, worin - die Länge und der Durchmesser (L und D) wenigstens das Vierfache des Innendurchmessers (D') des Pulvertransportrohrs (117) betragen.
10. Pulversprühpistole nach einem der Ansprüche 1 bis 5, worin die Vorrichtung zum mustermäßigen Versprühen, des Pulvers eine Düse (12) umfaßt.
11. Pulversprühpistole nach einem der vorhergehenden Ansprüche, worin das Pulvertransportrohr (17) relativ zur Elektrode (46) axial einstellbar ist.
EP19850300820 1984-02-27 1985-02-07 Pulversprühpistole Expired EP0154416B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US58389884A 1984-02-27 1984-02-27
US583898 1984-02-27

Publications (2)

Publication Number Publication Date
EP0154416A1 EP0154416A1 (de) 1985-09-11
EP0154416B1 true EP0154416B1 (de) 1989-08-30

Family

ID=24335059

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19850300820 Expired EP0154416B1 (de) 1984-02-27 1985-02-07 Pulversprühpistole

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Country Link
EP (1) EP0154416B1 (de)
JP (1) JPH0659425B2 (de)
CA (1) CA1245049A (de)
DE (1) DE3572605D1 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6796492B1 (en) 1995-04-13 2004-09-28 James G. Gatto Electronic fund transfer or transaction system

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2402209A1 (de) * 1974-01-17 1975-07-31 Mueller Ernst Kg Vorrichtung zum elektrostatischen ueberziehen von gegenstaenden mit fluessigem oder pulverfoermigem material
JPS5145143A (en) * 1974-10-16 1976-04-17 Ransburg Japan Ltd Funshapataanno choseiga kanona funtaitosoyofunshanozuru
US4245551A (en) * 1979-03-05 1981-01-20 Nordson Corporation Coating booth for electrostatic application of pulverized materials

Also Published As

Publication number Publication date
JPS60209277A (ja) 1985-10-21
EP0154416A1 (de) 1985-09-11
DE3572605D1 (en) 1989-10-05
JPH0659425B2 (ja) 1994-08-10
CA1245049A (en) 1988-11-22

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