DE1577617A1 - Electrostatic spray device for paint material u. like - Google Patents

Description

Patent attorneys "

Dipl.-ing.W "Beyej;" Dip! .- Wirtsch.-Ing, B.kochern

6000 Frankfurt am Main Freiherr-vom-Stein-Str. 18th

In terms of: / Az; P 15 77 617.7

Atlas Copco ■■■ ": ■ / ■;

ATctiebolag /

Nacka / Sweden. /

Electrostatic spray device for parB material and the like

Priority of US application no. 173 633 dated February 16, 1962

The invention relates to an electrostatic spraying device for paint material and the like, in which one with pressurized gas fed nozzle with a paint material nozzle together in such a way, has an effect that consists of atomized droplets of material and forms a jet directed away from the sprayer.

Spray devices in which a liquid is atomized by a separately supplied pressure medium and a large number of finely distributed droplets and this atomization is perfected electrostatically, are known in various embodiments. One of the main problems with atomization lies in the fact that the size of the _{λ remains as constant as possible}

At 7457 / December 10, 1968

909831 / Q77-8

• ". Jbieue documents

Single droplets, i.e. avoiding large droplets, which either by combining several small droplets or due to the uneven effect of the print medium. The danger of several people coming together small droplets should be eliminated or reduced in the known spray devices that the individual droplets are charged in the same direction by a high-voltage electrode arranged in front of the outlet nozzles, so that they more or less repel each other "

In order to favor the atomization effect, there are several known embodiments provided mixing chambers. These However, mixing chambers have the disadvantage that liquid particles are deposited on their walls, which then have a Build up a constantly growing layer. If this layer of liquid has a certain thickness, macro-droplets can be loosened from it by the air flow and undivided by the nozzle be carried out. This in turn significantly affects the continuous atomization effect.

It is, for example, a spray device for spraying known from leaves and leaves etc., in the case of the electrically charged Oil droplets are introduced into an air stream » The electrostatic charge of the droplets is thereby carried out with the aid of a needle point under high voltage,. which protrudes centrally through the nozzle and mixing chamber and its foremost part from a grounded metal ■ cap is surrounded. Due to the arrangement of the nozzle needle, the droplets are preferably charged in the middle Part of the outlet flow and decreases in the radial direction. Uniform charging is therefore not to be expected. A settling of liquid particles on the mixing chamber walls is of minor importance here because it This device is not a paint spray system

At 7457 / 10.12 * 1968

909831 / 677S

but rather an "open-air atomizer", in which possibly occurring macrodrops of less harmful influence are than, for example, with spraying devices in which large drops always lead to irregularities on the paint wall to lead" ;

It is necessary for the even application of the atomized paint furthermore advantageous and known, the paint air flow through to have a rotating nozzle discharged. These well-known Versions with a turbine nozzle are, however, without electrostatic Droplet charging operated.

The object of the invention is to provide an electrostatic spray device for paint material and the like. To create in which the occurrence of occurred in particular in the mixing chamber Large pots reliably avoided and the jet of paint before impact is delayed on the wall to be sprayed.

According to the invention this object is achieved in that the Pressure gas nozzle and the paint material nozzle within the spray ■■ -. direction of a known mixing chamber with a discharge opening formed by one or more spray slides downstream is assigned through which the beam when exiting its final shape can be imparted from the spray device, the mixing chamber and the dispensing opening being designed to be electrically conductive on their surfaces exposed to the paint jet, are isolated from the environment and exposed to high electrostatic voltage.

An advantageous embodiment of the spray device according to the invention is characterized in that the pressurized gas nozzle and the paint material nozzle are arranged axially, and that one A device is provided through which the mixing chamber and the Abgabeöffnund; are rotatable about the axis of the nozzles.

At 7457 / December 10, 1968

90 98 31 / © 7 7 p

Compared to the previously known embodiments, the inventive Spray device has the decisive advantage that the dye air stream is electrostatic after exiting the nozzles is slowed down, resulting in significant color savings The result is that fewer paint particles are dusted into the open environment will.

In the following the invention is based on exemplary embodiments explained in more detail in connection with the drawing. the Figures show:

Fig. 1 is a sectional view of an electrostatic Spray device according to the invention,

Fig. 2 is a plan view of a nozzle of the spray device according to Fig. 1,

3 shows a sectional view through the nozzle of a modified one Embodiment of the invention Spray device,

Flg.- 4 is a schematic sectional view of the nozzle another embodiment of the invention along the section line 4-4 in Fig. 5 and

EMg. 5 shows a section along the line 5-5 in FIG. 4. "

The electrostatic spray device according to FIG. 1, designed as a spray gun, has a barrel 10 made of electrical insulating material, which is carried by a shaft 11 with a handle 12 and an inlet 13 for a gaseous pressure medium, for example air. The device also contains a liquid inlet 14 for liquid coating material and a release lever 15, by means of which the inflow of air from the inlet 13 into the barrel 10 can be controlled with the aid of a valve 16. The release lever 15 also controls the dispensing of the liquid coating material by displacing a spindle 17 of insulating material backwards against the action of a return spring 18 provided between a sleeve 20 and the spindle 17. The At 7 «7 / 10.12.1968 909831/8775

The opening path of the spindle 17 can be adjusted by means of an adjusting nut IS be changed, which are provided with a screw thread Part of the sleeve 20 cooperates. The sleeve 20 is sliding /. ; but not rotatably arranged in the body 11 and forms a axial abutment for the spindle 17 · The front end of the Shank 11 receives a bushing 21 made of insulating material, preferably polyamide, with the interior of the liquid. inlet H der.ein polyamide connector, connected is. The spindle 17 leads through a plug 22 in the Socket 21 is screwed 'and a packing 23 sealingly between the bushing 21 and the spindle 17 press. On the front end of the shaft '11 a union nut 24 is screwed, the the barrel 10 connects to the shaft 11.

- - '■ ■ ■ ■

The barrel 10 consists of an inner tube 25, tubular end pieces 26,27, which are screwed to the ends of the inner tube 25, and an outer tube 28, which runs between the end pieces 26 ₉ 27, is tightly connected to them and the inner tube 25 with radial Distance surrounds. All of these parts 25 to 28, which form the barrel 10, consist of an electrically insulating material, preferably polyamide. The rear end piece 27 has a radial flange 29 and is precisely centered in a centering collar 31 by means of a centering cone 30 at the rear end. The collar 31 si-feather in a recess at the front end of the shaft 11 and encloses the socket 21 sealingly * The end piece 27 is versehraubt in the socket 21, and the union nut 24 cooperates with the radial flange 29 in such a way that the rear © re End piece 27 and the centering collar 31 are pressed firmly against the shaft Π, whereby the entire barrel 10 is held on the shaft 11. The spindle 17 extends forward through the bushing 21 and the barrel 10. A hollow cylindrical flow path 32 is formed around the spindle 17, via which the liquid coating material is fed to the nozzle end of the barrel 10.

The air inlet 13 is connected to an annular chamber 33 via an Ihirohflußweg containing the control valve 16.

909831/0775 It 7457

bound, which are formed in the shaft 11 around the bushing -21 and is sealed off by the centering collar 31. the end In the chamber 53, the air flows through axial flow paths 34, 35 in the centering collar 31 and in the rear end piece 27 through the annular channel 37 between the tubes 25 and 28 of the barrel 10 and arrives at the front end of the front end piece 26 through axial flow paths 38 arranged therein.

At the front end of the end piece 26 is a hollow nozzle body 39 screwed into the end piece 26 made of electrically conductive material. The body 39 centrally contains a nozzle 40 which dispenses the liquid and which is controlled by a needle valve 41 which forms the tip of the axially displaceable spindle 17. In the nozzle body 39 eccentrically arranged flow paths 42 for the gaseous pressure medium or air are also provided, which are directed so that they converge air jets lead forward. One forming an injection nozzle 43 metallic cup-shaped cap is coaxial on the dispensing end the nozzle body 39 is placed and through one with the front End piece 26 screwed union nut attached. Internally the union nut 44 an annular air chamber 45 is formed, the air from the passages 38 in the front End piece 26 receives and with the flow paths 42 of the mouthpiece body 39 is connected · Das.Spritzmundstück 43 freely surrounds the outlet opening of the liquid-dispensing nozzle 40 and forms the gaseous pressure medium or the Air outgoing nozzle 46 around the nozzle * Regarding the ' Nozzles 40 and 46 downstream form the nozzle 43 a mixing chamber 47 for the jet of liquid particles generated by the nozzle 46 and directed into the atmosphere will. This mixing chamber has an outlet in the form of a transverse injection slot ^ s 48, where the exiting jet side final cross-section shape

At 7457

909831 / © 775

In a through, - "" the Sprit ζ schilt ζ 48 and the longitudinal axis of the barrel 10 extending plane, attached to the Sprit zmund st tick 43, opposite insulated conductors 49 are provided, which between their forward ends a secondary electrode .50 in lorm a fine wire having ^ transversely gum course of the beam, and in that before the injection slit 48, i.e., "h _# is disposed in the Sbene the conductors 49" an electrically insulated oval ring 51 ■ »z _e B" of an isolated The wire ring can extend between the conductors 49 to prevent contact between the secondary electrode 50 and the object to be coated; additional secondary electrodes 52 can be provided in current-conducting contact with the conductors 49 to prevent the inside of the ring 51 will ^ um; prevent a deposit of coating material from the jet on HiBg 51 au,

The ■ -Stem 11 may be grounded via a wire 54 ₉ of the handle 12 is closed tight ο A well-insulated high =. Voltage conductor 53 1st. connected with one of the conductors 49y & oB _D mill to the SpritEmundatück 43g, in order to put in the stsOiilsitsndgn nozzles 40 and 46 and the Imndstüßt 43 as well as the llÄtrodendrähtä 50 and 52 at Hochspaxm: ü ^ apo "fe. @ atial _o

In operation & ®τ conductor 53 as a high voltage source in a "ElektrCstatäsehen Geaerators conventional type geD ^ tj during the llüsaigkeitseiäilasa 14 with a supply = · source for. Under B-ruels" at © feeades liquid cover material.1 and the air inlet 13 with- e ± .ß © r Bruekiuftquelle are connected _β The electro-statisohe '& sn © sator with the Spritapistolenöüeen. 40,4β and the ÄiimöstiiQlt 43 as well as the "Slektrodedraht- 5O ₉ ', ■ _ 52. On a fiofoesi negative - or positive potential opposite

At 7457

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the environment * eg 90,000 volts or more »while the object to be coated is at a low potential in relation to the nozzle end of the spray gun. After the spray gun has been brought to a sufficiently small distance from the object to be coated, the operator actuates the release handle 15. This pushes the spindle 17 with its tip 41 backwards by a predetermined amount, whereby liquid coating material through the flow 32 to the liquid dispensing nozzle 4-0 and exits there. At the same time, the annular chamber 33 is supplied via the valve 16 with compressed air, which through the passages 34, 35, 37 and 38 into the annular air chamber 45 and from there through the flow paths 42 into the nozzle 46 and into the mixing chamber 47 and finally into the atmosphere got. The liquid coating material is effectively atomized in the mixing chamber 47 by the air jet and the liquid particles are then directed through the spray slot 48 which retards the particles of the jet and defines the final cross section of the jet. Ζ simultaneously with the compressed air erstäubung occurs within and at the height of the nozzles 40,46 and in the mixing chamber 47, an electrostatic charge due to the high potential of the nozzles and thereby to passing corona discharge. Subsequently, the atomized material is electrostatically influenced by the field surrounding the secondary wire electrodes 50 and 52.

The electrode 50 creates an additional delay in the beam and a charge of the atomized liquid particles, causing them to be deposited on the object to be missed by the joint effect of the delayed air flow and the electrostatic forces are precipitated. Such a common Effect effectively eliminates irregularities of the electrostatic field at edges of irregularly shaped Objects, creating an evenly distributed coating

At 7457

909831 / Q775

is generated - while a sufficient delay of the air flow reduced the losses of coating material to the environment Blockages and the like. Phenomena such as occur in known fuel ζ devices with internal mixing chambers, are avoided due to the high potential of the spray nozzle, causing coating particles that may accumulate could be eliminated so that the nozzles are kept clean.

In the modified nozzle part according to FIG. 3, this in connection with an arrangement of handle, shaft and barrel according to FIG. is used, the secondary electrode and the forward-running conductors are omitted. The high voltage conductor 53 is directly connected to the injection nozzle 43. The front ■ end piece 26 can be rigidly connected to the outer tube 28 via a clamping screw 56 be connected, and a sealing ring 57 can be insert so that between the end piece 26 and - ^ ear 28 a seal arises »The modification in relation to Figs. T and 2 consists mainly in the arrangement of a plurality of wuerspritzschlitzen 58 which are directed forward from the mixing chamber 47 arranged parallel, at an angle, transversely or in some other form to each other could be. The slots 58 are used for the final Shaping the cross section of the exiting jet in one such that the coating particles of the jet are sufficiently retarded that there is no further retardation and charging of the particles with the help of secondary electrodes is required

In the modified nozzle part according to FIG. 4, the barrel 10 consists made of a one-piece polyamide 60 with a central Bore 61 for the liquid coating material and the spindle 17 With the outer end of the tube 60 is a metallic nozzle body 62 rigidly screwed, the opposite of the tube 60 through a conical surface 63 is centered. An annular chamber 64 is formed in barrel 10 near surface 63.

At 7457 909831/017 $

An air passage 65 directs air into the chamber 64. Axial flow paths 66 extend from the chamber 64

to
the nozzle body 62 t 'its outer end in the vicinity of the outer surface of a stepped cylindrical part 67 · On the part 67 a coating material dispensing nozzle 68 is formed with a forwardly directed tip. A metallic spray nozzle 70, which at a distance surrounds the offset part 67 and the liquid dispensing nozzle 68 and forms a converging conical air outlet gap 71 around the tip of the nozzle 68, can be rotated "x" g "i. *" Ti ^ with the aid of a nail bearing 69 mounted on a cylindrical part of the nozzle body 62. The spray nozzle 70 in turn has a mixing chamber 72 downstream in relation to the liquid discharge nozzle 68 for the air discharged through the gap 71. -

A radial flange 73 on the rear of the nozzle 70 is surrounded by a union nut 74, which is screwed to the barrel 10 and a holder for the Flange 73 represents · Inside the flange 73, the spray nozzle 70 has a turbine spoilage 75, and in front of this an annular discharge chamber 76 is arranged, which communicates with the atmosphere via radial openings 77 communicates. The turbine blading 75 forms a drive for rotating the spray nozzle 70 on the Nozzle body 62. An axial flow path 78 is formed in the barrel. It pushes air against the turbine blades 75 blown so that the nozzle 70 in rotation is moved. The air to flow path 78 is diverted at a suitable location, e.g. in the course of the spray coating device in the vicinity of the handle 12 according to FIG. 1, and can through the flow paths 79 and 80 to flow paths 78 and 65. At a

At 7457

90 9 831/0775

A suitable place is a valve 81 for regulating the. 'Air' ™ » -r * ii-jstromes through the flow path 65 to the air outlet gap 71 independently of the air flow to the turbine blading 75 provided®

A radially extending protective ring 82 on the spray nozzle 70 prevents the air turbulence emerging from the openings 77 from influencing the spray pattern of the jet emanating from the spray nozzle 70 and the gap 71. The jet liquid particles from said air ** outlet gap takes wirdp directed into Preie 71 its end "= valid form dureh a splash guard 83 .an, - that of the mixing chamber 72 from passing _f ζ .38" in a plane through the axis of rotation of the spray mouthpiece 70 »whereby it is directed at an angle with respect to the axis of rotation of the spray mouthpiece 70 ₀

The high-voltage conductor 53 can be connected to the. Barrel 10 as shown at 84 ₉ "attached © a ₉ " and has © inea connection - B ^ -, which slides on the mat area llant®lo "surface of the injection nozzle © 70.

In Betriefe die.Düsenanordnung decreases after, lig _o 4 air over the Strömungewegö 79 and 78 ', so that the Spriügmundstüek 70 Average The wircL the rotated! Purbinenbeschaufelung This 75 v / ith liquid material aas-over, the flow path 61 fed will j dTirofe ..die. Liquid discharge nozzle 68 directed and '■ in the MischkaMass ¹ 72 by the Itaftstrom atomized _r is äfegegslsen from the air gap 71 / to which the air across the flow path SO _8, the valve Sl ₉ - the chamber 64 and the · Strömurigs · lanes 66 out is "laughing atomization in the mixing = -? chamber 72 and-after-charging at high voltage, which di" electrically conductive nozzle 70 »71, 68 and the construction-voltage conductor 55 generates ₉ / the beam ird finally by the rotating Limited splash guard 83 is formed and is delayed when pedaling through the slot 83. ' Due to the radial

At 7457 9098.31 / 0775

The particles of the beam experience an additional deflection Delay before the deposition on the object to be coated, which is arranged in front of the nozzle end of the spray gun is. This arrangement can also be used to coat the inner surface used by tubular objects, such as ζ.Be * · pitchers will.

Patent claims /

At 7457 / April 12, 1967

909831/0775

Claims (1)

New patent claims Π '·) Electrostatic spraying device for paint material, etc., in which a compressed gas-fed nozzle with a paint material nozzle cooperates in such a way that a jet consisting of atomized droplets of material and directed away from the spray device is formed, d a through ge k e η η ζ e i c h η et that the pressure gas nozzle (46.71) and the parquet material nozzle (40,68) within the spray device a mixing chamber (47, 72) known per se with one formed by one or more spray slides (48 “58.83) Discharge opening is assigned downstream, through which the jet when it emerges from the spray device its final Form can be given, whereby the @ mixing chamber (4-7,72) and the discharge opening is designed to be electrically conductive from the environment on its surfaces exposed to the ink jet are insulated and subjected to high electrostatic voltage 2 · device nacfe claim 1 dad _t URC h- ge ea.nzeichnet k "that the Druckgasdüs® (71) and die.'Färb- '-naterialdiiee (68) are arranged coaxially vwä that" ine is provided, throughsh w «leh.e di @ Hiich-. (?) ie-. AbgabeSffming (^ ri "ö2e @ & lite d5) ^: tm the axis of the Ma © a are rotatable * Apparatus aaoh claim 2, .durch- ge k. @ η n- »■ ei ο h. η β t. that the dispensing opening (spray slot 83) is so aas @ ördn © t «that the one leaving the spraying device -. · 909331 / 077S / At 7457 V- 12 _S 4 _O 1967 "BAD ORIGINAL if Beam is directed transversely to the axis of the nozzle (6b or 71). 4. Apparatus according to claim 2 and 3, characterized in that that the mixing chamber (72) is formed by an atomizer mouthpiece (70) which forms the compressed gas nozzle (71) which encloses the outlet end of the paint material nozzle (68) with a radial distance and together with the dispensing opening (Spray slot 73) from a known per se Turbine drive (75) fed by compressed gas can be set in rotation. At 74-57 / April 12, 1967 90-9831 / 0775 Blank page