US3051394A - Electrostatic spray coating apparatus and method - Google Patents

Description

J. SEDLACSIK, JR

Aug. 28, 1962 ELECTROSTATIC SPRAY COATING APPARATUS AND METHOD 4 Sheets-Sheet l Original Filed Deo. l, 1955 Aug. 28, 1962 J. sEDLAcslK, JR

ELECTROSTATIC SPRAY COATING APPARATUS AND METHOD 4 Sheets-Sheet 2 Original Filed Dec. l, 1955 INVENToR. JOHN 6 DL s/K Je.

Aug- 28, 1 962 J. sEDLAcslK, .JR 3,051,394

ELECTROSTATIC SPRAY COATING APPARATUS AND METHOD Original Filed Deo. 1, 1955 4 Sheets-Sheet 3 Aug. 28, 1962 J. SEDLACSIK, JR

ELECTROSTATIC SPRAY COATING APPARATUS AND METHOD 4 Sheets-Sheet 4 Original Filed Deo. l, 1955 IN V EN TOR. JOHN .SEDLC/K JK.

United States Patent @ddee 3,051,394 Patented Aug. 28, 1962 3,051,394 ELECTRSTATIC SPRAY COATING APPARATUS AND METHOD John Sedlacsik, Jr., Garfield, NJ., assignor to Intex-planetary Research & Development Corp., Garfield, NJ., a corporation of New Jersey Original application Dec. 1, 1955, Ser. No. 550,373, now Patent No. 2,913,186, dated Nov. 17, 1959. Divided and this application Nov. 16, 1959, Ser. No. 853,404

6 Claims. (Cl. 239-3) My invention relates to new and useful improvements in electrostatic spray coating, and, more particularly, to coating apparatus and coating methods to be used in electrostatic coating systems. This application is a divisional application for Electrostatic Spray Coating Apparatus and Method, issued November 17, 1959, as Patent No. 2,913,186.

In electrotatic coating systems of the present known types, a eld of electrotatic force is created which includes the article being coated, the atomized coating material particles in movement toward such article, and the projection means by which the particles are set into motion in flight.

Normally, the article is mounted on a grounded conveyor so as to make the article itself (if it is of conducting material or an electrode adjacent the same, an electrode at ground potential. Another electrode at high electrical potential is provided, same normally being the spraying device.

This invention relates to improvements in apparatus for applying a liquid coating to an article by electrostatically charging and depositing the comminuted coated material upon the 4article within an electrostatic field created between the anticle to be coated and the issuing source of the coating material. The coating material is issued from a spray gun or similar suitable atomizing device preferably utilizing air under pressure as a vehicle to convey the tinely divided or atomized particles onto the surface of the article to be coated. FIG. l utilizes air to atomize and convey the particles onto the surface of 'the article to be coated, and also employs electrostatic deposition :by establishing the electrostatic field with the charging ring or charging electrode. However, in FIGS. 8 and 9, the 360 spray nozzle is within the confines of the cone, so that while the cone is sprayed by coating material emitted from the single source feed nozzle to provide an annular centrifugal spray, certain of the spray from the Ifeed nozzle is also urged forwardly from the center of the nozzle spray toward the article. The spray, whether projected centrifugally or under pressure, will have the particle-s charged electro-statically to provide electrostatic deposition of the coating material particles.

It is directed panticularly to providing means whereby arcing at the spray gun is obviated, direct contact between the high electrical potential and the gun being eliminated, the gun being charged, if at all, by induction only. lIn this invention, the gun is at a low voltage potential.

Speciiically, this invention relates to an atomizer capable of electrostatically charging liquids emerging from an orifice in the form of a jet or spray.

In the use of spray guns or the like of known prior art types, the :gun is usually limited :to a comparatively reducing this loss and waste of coating materials, of increasing the amount of effective coverage which may be small iield of dispersion. It carries the coating material to be discharged in non-uniform sized particles and in variable patterns. Thus there is an uneven dispersion of the coating particles over the surface to be coated due to the inertia generated in the discharge, causing the larger particles to travel 4further in the field than the more finely divided parti-cles. Sometimes a variable pattern of spray is created and reproduced on the surface to be coated, the heavier coating particles being caused to irnpinge over one area and the more finely divided particles over another area.

By reason of such variance, it has been found necessary under certain conditions of coating to arrange a sizeable battery of spray guns with particular regard to their variable patterns of coating application so that the several guns complement each other to even out the pattern as a battery.

One object of the present invention is to provide means for controlling lthe deposit of the sprayed material on the surface to be coated, thereby reducing and minimizing the waste of material due to loss lby dispersion into the atmosphere, and effecting substantial savings in labor and equipment while simultaneously increasing the coverage of the coating material.

`In prior art spraying devices, the spray mixture issuing from the spray nozzle spreads outwardly or expends uniformly taking the form of a generally conical mist-like stream. The sides of the stream travel outwardly in diverging paths in :the general direction of the surface to be coated. Upon impact therewith, considerable of the coating material, entrained with the air, is deflected in a swirling action away from this surface and i-s dispersed into the atmosphere. A great deal of the coating material discharged Ifrom the nozzle is thus lost and more material than actually needed is used to produce the desired coatbooths equipped with high powered suction or blowery systems in which to conduct the spray operations.

Here is an improved spray coating device capable of Where metallic materials ar-e employed, such as metallic paints, and where the head or discharge end of the gun itselif functions as the discharge electrode, there is a dangerous tendency of the gun to backfire, leading to a .dangerous lire hazard as well as a dangerous instrumentality insofar as operato-rsthereof are concerned.

Here, there is no direct contact between the discharge electrode and the head end of thespray gun, the head end being charge-d by induction.

The invention also provides means for controlling the diverging column or stream of atomized coating material after issuance from the spray nozzle so that lateral deflection and dispersion of the mixture along the margin of impact of the stream lwith the surface to be coated is appreciably reduced and so that a greater percentage of the material dispersed into the atmosphere is directed onto 'the article surface itself.

The invention contemplates the employment of a paint spray gun mechanism wherein the forward atomizing elements are isolated from the rearward control elements. The rear portion of the mechanism is at ground potential whereas the forward portion thereof is connected to the high electrical potential. Insulating means between these forward and rearward elements prevents the possibility of a transmit-tal of an electrical charge rearwardly from the forward area, all lfor the convenience and safety of the operator.

By isolating the atomizing head or gun tip from the support or control elements of the gun by insulating members, the desideratum of maintaining the smallest portion or area of the gun at a high potential is attained. In order to separate or insulate the high Voltage nozzle or atomizing head from :the control end of the gun mechanism, I employ connections between the Igun tip and the support or control elements of the gun which comprise non-conductors of electricity, they being of rubber, glass, ceramic, plastic, or similar non-conducting material. Thus, the support and control mechanisms, as well as the operator, .are safeguarded against dangerous back-tiring from the nozzle or head end.

Optimum results are obtained where the mass of t-he atomizing tip of the mechanism is as small as possible and Where the mass of the article being coated is relatively larger. This relationship facilitates leakage of the atomized material from the high potential tip of the mechanism to the article. That is to say, the smaller the area at the high potential, :the greater the rate of leakage of atomized material to the mass of the article lbeing coated.

The inherent electrical effect in prior art guns is for the particles more or less to repel each other so that lateral spreading results. This spreading phenomenona is especially noticeable at the outer portion of the spray or jet area where an uneven, irregular and indistinct edge definition to the pattern `of the coating material being deposited upon the article is observed.

By surrounding the atomizing mechanism with a sheath of electrostatic field which is substantially coeXtensive longitudinally with the former, the projecting spray is substantially stabilized and is made more definite in its shape and more constant in its direction. The scattered spreading effect upon the particles, particularly at the outer portions of the jet, is materially reduced resulting in a deposited pattern which is more uniformly dense throughout and which has the desired sharp edge definition.

In this invention, a source of electrostatic high potential, having one terminal grounded and its opposite terminal surrounding the atomizing head, creates a strong electrostatic field at the head by means of induction. The field extends between the head and the article to be coated, the article being grounded. The force of this field transforms the atomized coating material into a spray of charged particles and creates an attraction which pulls the spray toward the grounded article.

A potential difference of sufficient magnitude is maintained so as to create an electrostatic field in lthe region adjacent the discharge end of the discharge electrode. The coating material is normally supplied to the discharge end of the gun and the region of corona discharge therearound at a rate at which it can be electrically charged by Vcorona discharge most efficiently and effectively, following which the charged particles are directed in spray form toward and deposited upon the oppositely charged article.

Depending upon the viscosity and other characteristics of the material, the control of the supply is such as to permit the discharge of precisely the correct quantity and size of the particles so as to attain the greatest efficiency in the coating of the particular surface involved.

The foregoing and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein several embodiments of the invention are illustrated. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description, and are not to be construed as defining the limits of the invention.

In the drawings:

FIG. l is a side elevational view of the device of my invention with certain parts thereof broken away for purposes of clarity;

FIG. 2 is an elevational view on the line 2-2 of FIG. 1 with parts broken away for purposes of clarity;

FIG. 3 is an elevational view on the line 3 3 of FIG. 1;

FIG. 4 is an elevational view on the line 4-4 of FIG. 2;

FIG. 5 is a top view of the head or discharge end of the gun mechanism;

FIG. 6 is a side elevational view of the head or discharge end of the gun mechanism;

FIG. 7 is a side elevational view of the rear or control end of the gun mechanism;

FIG. 8 is a side elevational View of a modified form of the apparatus of my invention; and

FIG. 9 is a side elevational view of another modified form of the apparatus generally shown in FIG. 8.

In the practice of this invention, there is provided a discharge member having an atomizing head, a spray gun mechanism with which said discharge member is associated, a source of liquid supply, sources of air supply, and distributing means for transferring the liquid and air from their respective sources of supply to the control means of the spray gun and thence to the discharge membeifor atomization and dispersion.

For purpose of simplification, all of these members are not shown, they being more or less conventional in paint spraying apparatus but forming a part of this specitic invention.

Referring to the drawings more in detail, and more particularly to the preferred form of my invention selected for illustrative purposes, I have shown an arrangement of apparatus which is suitable for coating articles which are preferably moved along a path of article movement into, through, and out of a coating zone which the device of the invention, normally iiXed in location, projects.

What will be referred to as the control or rear end of the spray gun generally indicated by the numeral 2 and what will be referred to as the discharge or forward end of the spray gun is generally indicated by the numeral 4.

The metallic control end 2 and the metallic discharge end 4 are connected together in space relation by an in` sulating air conducting member `6, a pair of insulating coating material conducting members 8 and 10, an insulating needle actuating member 12, and an insulating port control actuating member 14. If desired, only one coating material conducting member may be employed.

By means of such insulating members 6, 8, 10, 12, and 14, the control end and the discharge end of the gun are integral and unitary, yet are separated from each other and held in spaced relation by the aforementioned insulating members for safety purposes.

The control end 2 includes a metallic body member 20 which contains an air cylinder closed by the cap or closure 22 at the rear end thereof.

' Air inlets 24 and 26 for supplying pressured air to the air cylinder and atomizing air to the spray head respectively are provided.

Air supplied from sources of supply (not shown) is brought forwardly to the air inlets 24 and 26 through distributing means, such as connections (not shown).

Forwardly of the air cylinder, an L fitting 28 is provided having an inlet means 30 for the reception of the coating material into the gun mechanism.

Coating material from a source of supply (not shown) is brought forwardly to the inlet 30 through distributing means, such as a connection (not shown).

Pressurized air entering through inlet 24 serves to actuate the needle actuating member 12.

Atomizing air entering through inlet 26 is conducted through the air conducting member 6 to the forward end of the gun.

Coating material entering through inlet 30 is conducted through the material conducting member 8 to the forward end of the gun. Such coating material as is not used thereat may be recirculated rearwardly through the material conducting member 10 for recirculation back into the member 8. As aforesaid, if desired, this recirculation feature may be eliminated.

All of the above described mechanisms will be described more in detail in connection with the description subsequently to be made with reference to FIG. 7. Reference is made momentarily to the general construction of the apparatus shown in FIG. l, however, in order that the broad features of the invention may be initially understood.

At the head end of the gun, the insulating members 6, 8, 10, 12 and 14 are connected to the discharge end 4 in a manner subsequently to be described in detail in connection with a description of FHGS. and 6.

A plastic tubular sleeve 32 encloses the insulating members 6, 8, 12 and 14 and the head end 4 of the gun mechanism and is supported relative thereto by one or more spider members 34 made from a Suitable insulating material, `such as plastic, glass or the like. The spider member may be of two pieces held together as by screws 35 or the like as shown in FIG. 2.

The control end 2 of the gun mechanism supports an upwardly extending post member 40 from which a horizontally projecting rim 42 extends. A stud member 44 is threadedly engageable through the member 42, as shown, and is additionally engageable with the sleeve 32 so as to aid in the support thereof in yan axis parallel to axes of the members 6, 8, 10, 12 and 14.

The upper extremity of the member 40 is provided with a pair of spaced clamping rings 46 which hold a longitudinally extending support member 48 which may be of plas-tic, glas-s or similar nonconducting material. Tightening nuts 47 may be adjusted so as to ensure the clamping of the member 48 by the rings 46.

At the forward end of the support member 48, a more or less annular grid ring or discharge electrode, generally indicated by 52, is located, same being held relative thereto by means of an insulating coupling member 54, which may be internally threaded as yat 55 -so yas to be threadedly engaged with the free end of the member 48, as shown.

The grid ring 52 comprises a copper tube S6 which is completely enclosed throughout its length by a plastic covering 58. At spaced intervals throughout its length, metallic needles 60 are disposed, they being fixed to the copper tube 56 and extending outwardly therefrom through the covering 58. The electrical charge is directed outwardly through the exposed portions of the needles, optimum results being obtained when the points of the needles only are exposed so that increased ionization results.

The needles 60 do not extend outwardly beyond the outer surface of the covering 58 whereby wiping of the annular grid discharge member 52 as by a cloth or the like is facilitated.

At the uppermost extremities or ends of the member 52, openings 64 and 66 are provided into which the free end of -a high potential lead line may ybe inserted. The lead line is inserted into an opening 64.

Ordinarily where only one such gun mechanism is em- 6 ployed, the other opening 66 would be plugged by an insulated stopper (not shown).

If it is desired to connect the discharge grid to another discharge grid adjacent another gun apparatus, as in a series, a lead line could be run from the opening 66 to lche related opening in `a second discharge grid.

The grid discharge 52, lbeing annular in configuration, surrounds the tubular sleeve 32, as best shown in FIG. 2, and may be adjusted forwardly and rearwardly relative to the head end of the gun in order to viary the degree of induction at the head end of the gun. The discharge electrode 52 is preferably set far enough back relative to the sleeve 32 that `arcing over to the front or head end of the gun within the open -front end of the sleeve is prevented.

The grid discharge member 52 provides a primary guard again-st arcing between the high potential rand the head of the gun. The sleeve member 32 provides a secondary guard thereagainst. These safeguards are particularly desirable in the case of metallic coating materials where undesired ancing :from the discharge electrode to the head of the gun could -and often does result in backfiring of the electrical potential rearwardly to the control end of the gun a-nd possibly even tothe source of supply of the coating material.

The heart of this invention lies in the feature above described. By means thereof, the head end of the gun is grounded thereby making it possible to get closer to the work with the hea-d end, all to the end that the coating material can be more efficiently and effectively pushed into areas which are restricted such las areas between closely spaced walls and the like, -as for example in the case of radiator iins. The principle involves setting the grid rearwardly of the head end of the gun so as to permit the use of regular paint spray gun. The high potential grid discharge being an integral member, separate and 4apart from the head end of the gun, the same can be adjusted forwardly and rearwardly relative thereto, all as desired, without effecting any changes or adjustments in the head end per se.

The higher the voltage employed, the further to the rear the grid discharge 32 is disposed, it being appreciated that the Voltage may conceivably reach as high as 250,000 volts.

The general features of the appartu-s having been described, particular reference will now be made to FIGS. 3-7 for 'an explanation of the details of construction of the various components of the gun mechanism.

The control or rear end of the spray gun 2 is best shown in FIG. 7 and comprises a body member 20 which encloses an air cylinder bore 100. The bore is closed at the rear end of the body member 20 by means of the cap or closure 22 which is threadedly engaged with the member 20.

Air inlet 24 is in communication with the bore 100, and admits pressurized lair thereinto for the purposes of actuating the needle valve actuating member i12 which is provided with a rearward extension 104 extending rearwardly yfrom the member 12, through a packing nut 106 into the body 20. The opposite end of the extension 104 constitutes lan axially positioned valve member 108 which moves longitudinally through la pack-ing nut 110. An annular plunger 112 is threadedly engaged with the free end of the valve member 108 and reciprocates within the bore 100.

The plunger 1212 and member 108 are urged forwardly by means of a spring 114 `disposed between the plunger 112 and the cover member 102. The spring 114 urges the needle valve forwardly to keep it in a normally closed position.

When the air enters the inlet 24, it travels to the bore of the `air cylinder -at the forward side of the plunger and forces the plunger rearwardly against the action of the spring 114.

A needle adjusting screw member 116 is threadedly engageable with the cover member i102 for manual adjustment relative thereto. This member maintains a manually variable tension on a small compression spring 118 disposed therein Ias shown. The spring 118 resists the opening movement of the plunger 112.

The member `116 is adjustable whereby the resistance of the spring 114rnay be increased or decreased.

As lthe valve member 108 is withdrawn rearwardly away from its seat, atomizing ai-r entering through the inlet 26 is conducted through passages 120 and i122 through a coupling 124 which is engaged with and in communication with the member 6, In this manner, the atomizing air is communicated to the forward end of the gun mechansim.

Coating materia-l passes through the inlet 30 into and through passage 29 in the fitting 28, in communication therewith, and through a coupling 128 engaged with and in communication with thefitt-ing 28. The member 8 is connected to the fitting 28.

The head or discharge end of the apparatus is best shown in FIGS. and 6. It comprises a-n inner fluid metallic nozzle 202 formed with -a tip 204 through which the coating material is emitted and an outer metallic nozzle 206 which controls the air.

The rear end portion of the nozzle 202 is enlarged at 208 and is connected in any suitable manner with the metallic body member 210.

The enlarged portion 208 of the nozzle 202 is formed with a suitable seat against which the lair nozzle 206 is held by a union nut 212 or other suitable means.

The fluid tip 204 is provided with a central orifice through which the 4emission of the spray material is controlled by a needle 214.

The 4central outer portion of the air nozzle 206i is in the form of a cap enclosing an annular air space 216l having a main discharge orifice 217 surrounding lthe fluid tip 204.

The nozzle 206 is provided with a pair of forwardly and outwardly projecting horns 218 provided with oppositely disposed orifices 220 through which flattening air jets are discharged at an angle to the spray stream -in a well known manner.

The central cap-like portion of the air nozzle 206 is also provided with a pair of opposed orifices 222 disposed at angles to the orifices 220. The orifices 222 are located comparatively close to the main discharge air orifices 220 and have a smaller angle of convergence than the orifices 220 so that the air jets emitted from the orifices 222 impinge at a comparatively small angle against the spray streams between the fluid tip 204 and the region in which the flattening jets from the orifices engage and flatten the spray streams.

The smaller air jets from the orifices 222 impinge against the spray streams between the end of the tip 204 and the vertex of the flattening jets from the orifices 220.

The smaller jets also add to the atomizing air emitted from the orifice 217 in such a manner as to reduce the forward blow of the center air. This reduction of velocity helps to eliminate the wavy effect which occasionally appears as a result of the force with which the spray hits the surface being coated.

The body .member 210 is provided with coupling members 230 and 232 whereby the members 6 and 8 and 10 respectively may be connected therewith.

Passageway 234 in communication with the passageway in member 6 leads the air therethrough past a control member 236 to the air space 216.

The control member 236 is adjustable transversely so as to open or close the passageway 234. 'The member 236 is held relative to the body member 210 by means of a nut 238 with which it is in threaded engagement. It has an outer free end portion 240 which carries a journal member 242. Member 242 has a gear 244 integral therewith.

Gear 246 supported by a journal in a bracket 248', is

u fixed to the forward end of the member 14 so as to be rod tated thereby.

Gears 1244 and 246 are in mesh so that upon manual ro tation of member 14, the opening through the passageway 234 may be adjusted as desired.

At the control end of the gun, the member 14 is journalled in bracket 250 on post 40. A manually engage- .able handle 252 at the free inner end of the member 14 thus permits the adjustment of the control member 236.

A stufiing box 260 is disposed rearwardly of the body 210 and the needle 214 is extendable therethrough thereby the extending free end thereof is fixed to the member 12.

A modified form of the invention is shown in FIG. 8 wherein the rear end portion, generally indicated by 302, and the forward or discharge end portion, generally indicated by 304, are connected by an insulating air conducting member 306, an insulating coating material conducting member 300, an insulating needle valve actuating member 312, and an insulating part control actuating member 314.

In this modified form, only one coating material conducting member is shown instead of two, for purposes of simplification, although it will be understood that the two members (of the recirculating type) can be employed, if desired.

The control -end includes the body member 320 containing the air cylinder closed by the closure or cap 322 at the rear end thereof.

The adjusting screw 316 is associated with the closure 322 as before.

Air inlets 324 and 326 for supplying pressurized air to the air cylinder and atomizing air to the spray head are provided.

An L fitting 328 is provided having an inlet means 330 for the reception of the coating material into the gun mechanism.

As in the case of the disclosure above, air entering inlet 24 serves to actuate the needle actuating member 312 and air entering inlet 326 is conducted through the body 320 to the air conducting member 306 and thence forwardly to the head end of the gun.

Coating material entering through inlet 330 is conducted ythrough the L member 328 and the material conducting member 308 to the head of the gun.

At the head end of the gun, the body member 350 supports and is connected with the members 306, 308, 312 and 314.

At the forward end of the body member 350 an atomizing head 352 of the type shown in my copending application, Serial Number 481,162, filed January l1, 1955, and now Patent No. 2,894,691, is employed and is secured thereto by means of a union nut 354.

The head 352 is enclosed within a cylindrical sleeve member 356 to which is fitted a conical shaped dispersing member 358. Members 356 and 358 are unitary and are rotatable relative to member 352, the outer wall of member 352 functioning as a journal for the sleeve member.

An annular driven gear 360 is fitted to the sleeve member 356 and is engaged by a driving gear 362 which is fitted to the forward free end of an insulating driving rod 364 supported relative to the body member 350 by means of a journal 366. The rearward free end of the member 364 is engaged with a driving motor 368.

The atomized spray of coating material and air emanating from the tip of the feed spray head 3'52 is directed onto the inner wall ofthe conical dispersing coating spray member 358.

This member 358 extends coaxially of the spray head and serves as an outer spray head in that its outer opening -has an enlarged diameter. 'I'hat is, the member 358 is provided with a wall that tapers outwardly.

The cone member being hollow, the atomizing coating material is metered at the desired rate to the apex thereof.

Rotation of the cone member spreads the material uniformly over its inner surface causing the material to fiow 9 evenly to the outer edge thereof, to effect an even coating on the article sprayed by the feed spray from the spray head 352 which feeds the cone and also sprays forwardly to coat the article, while the coating spray from the cone 358 only centrifugally atomizes or outwardly projects the particles of coating material to be deposited electrostatically.

In operation, the liquid material and air issue from their respective orifices in the atomizing head in the form of high velocity streams where they mix with each other under pressure; The resulting mixture is directed outwardly with high turbulence in the form of a finely divided stream.

Certain of the atornized material is caught by the inner surface of the rotating cone member where the same flows evenly toward the outer edge thereof from which it is projected toward, in spray form, and attracted to, the object to be coated.

As the stream is directed outwardly away from the nozzle, it is subject to the ionizing effect of the discharge grid, heretofore described, which surrounds the gun mechanism. By such means, the finely divided particles comprising the spray a-re each charged with electrical charges of like polarity and of substantially equal potential with respect to the electrode.

The positively charged particles are attracted to the nearby grounded objects to be coated. 'Ihe particles are attracted to and precipitate in a layer upon the grounded surface.

In FIG. 9, I have shown a modified form of the invention shown in FIG. 8 wherein the atomizing head 452 is fixed to the body member 450 by means of coupling member 454.

As in the case of the other modified forms of the invention the head end of this gun member is supplied with material through conduits `406 and 408 and is provided with a needle actuating valve member 412.

The driving rod 464 is journaled to the body member 450 by means of a bracket 466 and the forward free end of the member 464 is provided with a conical member 458.

The atomized spray of coating material and air emanating from the tip of the spray head 452 is in this instance directed onto the outer wall of the conical dispersing member `450.

While several embodiments of the invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes mayl also be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. An atomizing device adapted to provide a spray of coating material for coating an object, said device comprising an air pressure actuated spray gun having a spray head, conduit means coupled to said spray head for feeding liquid coating material and compressed air to saidl spray head for projecting a spray of liquid coating material therefrom, said spray head comprising a nozzle coupled to said conduit means and having surfaces to provide a 360 radially projected spray of comminuted coating material, an atomizing head mounted to rotate about the free end of said nozzle for receiving at least a portion of said spray and having a peripheral edge extending axially beyond the free end of said nozzle for projecting therefrom comminuted coating material received on said cone from said nozzle, means for rotating said atomizing head, and means for establishing an electrostatic field in the area of said spray head for charging said comminuted coating material and depositing same upon the surface of said object, last said means including a charging electrode remote from the atomizing head.

2. An atomizing device adapted to provide a spray of coating'material for coating an object including a spray head, coupling means coupled to said spray head for feeding liquid coating material thereto, said spray head comprising a pressure actuable nozzle adapted to provide a 360 radially projected feed spray of coating material particles, an atomizing head mounted to rotate about thefree end of said nozzle and positioned for receiving certain of the feed spray of coating material particles, said atomizing head having an atomizing edge extending beyond the free end of said nozzle, means for rotating said atomizing head and mechanically projecting from said atomizing edge particles received' on said atomizing head from said 360 radially projected feed spray, and means for establishing an electrostatic field adjacent said spray head for electrostatically charging the particles of coating spray projected from said atomizing edge for electrostatic deposition of said particles on the surface of said object, last said means being located remotely from said spray head.

3. A method of coating an article with electrostatically charged particles of coating material comprising, providing a spray of particles of coating material with certain of said particles of said spray having a forward velocity component to project said certain of said particles substantially axially toward said article, said spray of particles also including a lateral velocity component to direct certain other of said particles of said spray laterally, collecting said other of said particles having the lateral velocity component and projecting same radially to provide an annular spray pattern of particles, and establishing a voltage differential between said article and said particles for charging the particles of the axially and radially projected spray components to facilitate deposition of the particles on the article electrostatically.

4. A method of coating an article with electrostatically charged particles of coating material comprising, providing an initial pneumatic spray of particles of coating material with certain of said particles of said spray having a forward velocity component to project said certain of said particles toward said article to provide a forward central spray portion, said spray also having a lateral Velocity component to direct certain other of said particles of said spray laterally, collecting said other of said particles having the lateral velocity component and centrifugally projecting same radially to provide an outer spray portion, and establishing an electrostatic field in the area of said particles of said central spray portion and said outer spray portion for electrostatically charging said spray portions to establish a final spray pattern of particles directed generally toward said object.

5. An atomizing device adapted to provide a spray of coating material for coating an object, said device comprising a first coating material dispersing head, conduit means coupled to said first coating material dispersing head for feeding liquid coating material under pressure thereto for projecting said liquid coating material from said first coating material dispersing head, said first coating material dispersing head having surface means to provide a 360 degree projected feed of coating material a portion of which impinges a second coating material dispersing head, a second coating material dispersing head mounted to rotate adjacent said first coating material dispersing head for receiving at least a portion of said 360 degree projected feed and having a peripheral edge for projecting therefrom comminuted coating material received from said first coating material dispersing head, means for rotating said second coating material dispersing head, and means for establishing an electrostatic eld in the area of said atomizing device for charging comminuted coating material projected from said first and said second coating material dispersing heads.

6. An atomizing device adapted to provide a spray of coating material for coating an object, said device comprising a first coating material dispersing head, conduit means coupled to said first coating material dispersing 1 l head for feeding liquid coating material under pressure to said lrst coating material dispersing head and projecting said liquid coating material therefrom, said first coating material dispersing head having surface means to provide substantially a 360 degree projected spray of comminuted coating material, a second coating material dispersing head mounted to rotate adjacent said first coating material dispersing head for receiving at least a portion of said 360 degree projected feed on an outer surface thereof and having a peripheral edge for projecting therefrom comminuted coating material received from said first coat- 12 ingA material dispersing head, means for rotating said second coating material dispersing head, and means for establishing an electrostatic field in the area of said atomizing device for charging comminuted coating material projected from. said firsty and said second coating material dispersing heads.

References Cited in the file of this patent UNITED STATES PATENTS SedlacsikI June 14, 1955 2,809,902 Ransburg Oct. 15, 1957

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