US3233831A

US3233831A - Electrostatic spraying apparatus having vortex atomizing construction

Info

Publication number: US3233831A
Application number: US285470A
Authority: US
Inventors: Fraser Reginald Percy
Original assignee: Sames Mach Electrostat
Current assignee: Machines Electrostatiques SA
Priority date: 1962-06-04
Filing date: 1963-06-04
Publication date: 1966-02-08
Anticipated expiration: 1983-02-08
Also published as: DE1577917B2; FI42180B; BE633198A; DE1577917A1; ES288705A1; CH393149A; GB1023721A

Description

Feb. 8, 1966 R. P. FRASER 3,233,831

ELECTROSTATIC SPRAYING APPARATUS HAVING' VORTEX ATOMIZING CONSTRUCTION Filed June 4, 1963 5 SheelZS--Sheefl 1 Feb. 8, 1966 R. P. FRASER 3,233,831

ELECTROSTATIC SPRAYING APPARATUS HAVING VORTEX ATOMIZING CONSTRUCTION 3 Sheets-Sheet 2 Filed June 4, 1963 IOI 424 los 32 33 25 FIGA FIGB

Feb. 8, 1966 R. P. FRASER 3,233,831

ELEGTROSTATIC SPRAYING APPARATUS HAVING VORTEX lA'IOMIZINC- CONSTRUCTION Filed June 4, 1965 5 Sheets-Sheet 5 'static f charge thereon.

1 extending through the barr'elportion.

United States Patent t() 3,233,831 ELECTROSTATIC SPRAYING APPARATUS HAV- ING `VORTEX ATOMIZING CONSTRUCTION Reginald Percy Fraser, Kingston Hill, Surrey,fEngland,

assignor to Societe Anonyme de MachinesL Electrostatiques, l Grenoble` (Isere), France, :a French body corporate Filed June 4, 1963, Ser. No. 285,470 Claims priority, application Great Britain, June 4, 1962,

21,493/62 16 Claims. v(Cl. 239-15) This invention relates to pneumatic electrostatic-spraycoating of objects with liquids, and particularly to pneu- `matic electrostatic spray painting.

The present invention consists in pneumatic electrostatic sprayingV apparatus wherein the liquid to be `sprayed is discharged -under pressure into a vortex of gaseous fluid, means being' provided to electrostaticallycharge the liquid at or before-'its point .of vdischargeintothe vortex.

-iThevr liquid may be discharged vthrou'gh afirst nozzle opening fdisposed coaxially 'within -a-*second nozzle 'open- -fing-whichl is' annular'and through which the gaseous `uid is discharged to producela gaseous vortex-whichatomizes *the liquid discharged "through the 'first nozzleopening y and carries along/with it the atomized liquid` particlesA towards the object to` be coated, vthe charged particles being attracted lto' the object by reason of-the electrovBoth nozzle openings (may be -formedin-.lthe same nozzle device.

vThe liquid is preferably dischargedas'a thin divergent conical'l lm of:` liquid which is coaxial with ythe axis of the gaseous vortex.

In order that l'the `invention' may be more lclearly understood, various* embodiments thereof will nowibe described with reference 4to the*accompanying drawings, -in-v'vhich:

'FIGURE l is al longitudinalaxial sectional -`view,with certain portions shown in elevation, of one embodiment offportable hand spray gun 'according to the'invention, 'together withl a perspective representationofia supply'of spraying material,

" atomizing Land spraying-head 'of `the -gun shown in' FIG- URE l,

'FIGURE 3 is-a transverse `'section lon the lines'A-'A AFIGURE V4 vis a transverse-section on theV lines lB-B YFIGURE 5 isan axial section ofthe spraying `head `portion of another embodiment of a spraying apparatnsaccoding tothe invention, and Y vFIGURES-'6, 7 and 8- arefragmentary'axialsectional views showingl further embodiments of lthe nozzle.

Referring now tOFIGURETLthere is '-shown1 a hand spray gunembodying the: present invention and comprising abarrel portion 101.and handf grip portion. 102. A

detachable spraying -head y"-Tv is mounted at'V the 'end' of the barrelportion'll. The spraying'head T- may be supplied vwith compressed air through afpas'sage`103' in the barrel portion and also 4have a high D`.C. voltage applied thereto by means lofaf'hi'ghten'sioncable`10'4 also The air supply lline and high tension cable passup through Vfthe 'handy grip portion of the gun. Anger operated trigger105T is con- `nected to a rod'106 also passing through the barrel of the.I gun, and "operation ofthe trigger controls the ejection 'of thepaint or otherjliquidV to be sprayed from the'head T, as will' hereinafter be described. The paint or other liquid towbe sprayed is Supplied .under pressure from a container 107Y through a pipe 1'08 to the spray head T.

The spray head T will now be further described with a seal at the rear end of the passa-ge. kju'strnent of the pin .18'is eiected by means of the trigger lPatented Feb. 8, 1966 ice reference to FIGURES 2 to 4 of the drawings. In Vthese figures the sprayv headT comprises a.housing-1 intthe front end of which is screwed alnozzle head 2 having' a coaxial bore 3 extending therethrough, the'tbore being enlarged adjacent its outer end to form a cylindrical chamber 4 having the inner lsurface. of its outer end wall y of the Apaint or other liquid `to be sprayed to the znozzle,

and within the passageis located a pin 18 having a conical head 19 adapted to seat ina conical recessr20 at the front end of the passage 17. The'pin'18 hasa stem'21 of reduced vdiameter adjacent the head 19. Extending radif ally from the. stem' 21 and spaced from the. heady 19 are longitudinal ribs '22 for locating thehead centrally .with

'respect' to the passage 17. The. passage is` enlarged at 23.and is providedwith a connectionf24, 25 from pipe 108 throughfwhich the `liquid to She-sprayed fed from theicontainer 107 can be supplied under pressure to the passage 17. The washer-27 secured by screw Ztl forms LongitudinalY ad- 105 through the rod 106. The rear end of the l'pin is .threaded'at 26 for 'connectionto the rod 106. VThe head 1T is fixed to the barrelfportion 101 by thescrews 29 which also pass througha-angellfon the nozzle 9. The high D.C. voltage is fed through the cablef104 to a resistor-31 connected through `a spring'32 to a-.block 33 .offhigh-.resistivity material directlyzin ycontact with Ithe -rcoating Vliquid in the connection V24.

-With the exceptionV of` the: high. tension cable104,the

Vspring-'32-y and the highly resistive block 33, all of Vthe parts of the barrel 101 and theheadT may be made of electrical insulatingmaterial, or alternatively :the pinv 18 maybe made of'a conducting or Ahigh'resistance.material and be connected to the'high voltage: sourceand` serve las the electrode .for charging thefliquid as itisfdischarged from therdevice. v

Inoperation, compressed airis fed lthrough the pas- 'sage `103 to the housing 1, and on entering the chamber 4 through the passages- 6, produces a rapidly rotating mass oair-arida vortex upon-discharging through the lannular fgatp between theend 10 of they nozzle-9 and the edge 5.

Paint or otherliquid is discharged und-er pressure through the .annular gap-.between the conical head19 and the fendf 10 in'theform of a thin divergent conical .lilm 0f liquid, coaxial' with the axis of the air vortex, and distributed 'in theA gases'of the vortex,whichatomizesfthe liquid. The liquid is electr-ostatically charged v-as it is di-schargedfwithin the vortex. y

FIGURES is a sectional view of-a furthervem'bo'diment Vof spray :head in whichl it isy possible toadjust the annular .gap through which the compressed air vortex passes.

`Longitudina'llyslidable in the bore.3 is a nozzle adjuster l39 having a `tapered end 10 which projects into the h-ole defined by the shanp edge 5, the taper of the end 10 being more acute :than the taper of the`end wall of the chamber '4, so Vthat the annular gap between the tapered end 10 and the chamber end wall can be varied `by axial adjustment of the adjuster A39. VThisl is `effected by rotation of thek member 11 threaded on to the end'12'of-the adjuster 39 which projects'out of thel rear end ofthe h-ousing 1, the intermediate part 13 of the adjuster 39 sliding through a hole in the rear of the housing and being surrounded fby a `thick Washer 14 of resilient material, such as rubber, which is compressed ybetween the internal sur- Piace of the rear wall of the housing and a-c-ollar 15 screwed onr to the intermediate part 13 of the adjuster. The washer 14 serves both for preventing leakage of air through the rear of the housing and also for holding the adjuster 39 forwardly in `accordance with the adjustment of the member 11. Between the member 11 and the back of the housing there are located ball bearings 16. The pin 118 is also longitudinally adjustable by means of the knob 4o secured in adjustable position -by mean-s of a counter screw 41 on the rear end of the pin 18. The compressed `air inlet 4is shown at 42 and the inlet for the coating liquid at 43. This spray head may form part of either a iixed or porta-ble apparatus.

`FIGURES 6, 7 and 8 show some modified shapes which the -en-d of the passage 17 and the end of the pin 118 may have, instead of the conical shape described above.

Whilst particular embodiments have been described, it Will 'be underst-ood that Various modifications may be made without departing from the scope of the invention. lFor example, the adjuster 39 may constitutea hollow electrode for charging the liquid in addition to or instead of the pin 18. The electrode may be made of high resistance material, or be made 'of insulating material with `a coating of a high resistance material in Contact with the liquid. In another embodiment, if the liquid itself is :sufficiently conducting, all the lptarts exposed at the front of the dev-ice may be made of insulating material, the liquid being in contact with an electrode as it Hows towards the discharge nozzle and the liquid particles becoming electrostatically charged as they are released into the vortex.

Whilst the device shown is in the form of `a hand spray gun, the features of the invention can also be incorpora-ted in a liixed spraying installation.

:I claim:

1. Electrostatic spraying apparatus, comprising a sup ply of coating material, :iirst nozzle means communicating Wit-h said 4supply f-or discharging particles of said material along a iirst path, said first nozzle means including means for directing the individual particles of said material in substantially `linear directions along said first path, means for electrostatically charging said material prior to its discharge from said iirst nozzle means, a source of iiuid under pressure, .and second nozzle means connected to said source for producing .a vortex of said diuid and for discharging said vortex along a second path intersecting said rst path, said first nozzle means discharging the linearly moving particle-s of material into said vortex to thereby atomize said material.

2. Apparatus for coating objects with a supply of coating material, comprising first nozzle means communicating with said supply for discharging particles of coating material therefrom along a first path, said iirst nozzle means including means for directing the individual particles of said material in substantially linear direc-tions along said rst path, means electrically connected `to said iirst nozzle means for electrostatically charging said material, and second nozzle means operatively associated with said iirst nozzle means for producing a vortex of gaseous lfluid and for discharging said vortex along a second path intersecting said iirst path, said iirst -nozzle means discharging the linearly moving particles of material into :said vortex to thereby atomize said material.

3. Electrostatic spraying apparatus, comprising a supply of coating material, r-st nozzle means communicating with said supply for discharging particles of said material along a iirst path, said first nozzle means including means for directing the individual particles of said material in substantially linear directions along said first pat-h, mean-s vfor electrostatically charging said material, a source of fluid under pressure, and second nozzle means connected to said source and operatively associated with said rst nozzle means for producing a vortex of said fluid and for discharging said vortex :along a second path, said second path intersecting said iirst path at .an acute angle, said irst nozzle means discharging the linearly moving particles of material into said vortex to thereby atomize said material.

4. Apparatus -for coating objects with a supply lof coating material, comprising a nozzle head having a discharge chamber therein, first nozzle means positioned Within said discharge chamber and communicating with said supply for discharging a spray of material therefrom 4along a iirst path, means forelectrostatically charging said material prior to its discharge from said 'iirst nozzle means, a source of fluid under pressure, and conduit means interconnecting said'source of fluid and said discharge chamber for producing a vortex of said fluid, said nozzle head `and said first nozzle means forming second nozzle means for discharging said Vortex from said chamber -along a second path intersecting said `tirst path, said first nozzle means discharging the ch'argedmaterial into said vortex to thereby atomize said material.

5. Electrostatic spraying apparatus for coating-objects with a supply of coating material, comprising a nozzle head having a. discharge chamber therein, irst nozzle means movably positioned Within said discharge chamber and communicating with saidvsupply for discharging a spray of said material along a first path, means electrically connected to said iirst nozzle means for electrostatically charging said material prior to its discharge from said rst nozzle means, a source of fluid under pressure, conduit `means interconnecting said source of iiuid and said discharge chamber for admitting said uid thereto, said nozzle head and said first nozzle means forming second nozzle means for discharging said fluid from said chamber along a second path intersecting said first path, said first nozzle means discharging the charged material into said uid to thereby atomize said material, and means for moving said iirst nozzle means relative to said discharge chamber to vary the rate of discharge of said uid therefrom. Y

6. Electrostatic spraying Vapparatus for coating objects with a supply of liquid coating material, comprising a nozzle head having a discharge chamber therein, rst nozzle means movably positioned Within said discharge chamber and communicating with said supply for discharging a spray of said material along a rst path, means for electrostatically charging said material, a source of gaseous fluid under pressure, conduit means interconnecting said source of uidvand said discharge chamber for producing a vortex of said uid, said `nozzle head andk said first nozzle means forming second nozzle means for dischargingV said vortex from said chamber'along a second path intersecting said tirst path, said iirst nozzle means discharging the charged material into said vortex to thereby atomize said material, and means for moving said iirst nozzle means relative to said discharge chamber to vary the rate of discharge of said tiuid therefrom.

7. Apparatus for coating objects with a supply of coating material, comprising a nozzle headdeiining a iirst bore having a discharge chamber adjacent one end thereof, rst nozzle means positioned in said first bore and having a second bore communicating with said supply of coating material for discharging material from said supply along a tirst path, means for electrostatically charging the material in said second bore, a source of fluid under pressure, and conduit means interconnecting said source of fluid and said discharge chamber for admitting said fluid thereto, said nozzle head and said first nozzle means forming second nozzle means for discharging said fluid along a second path intersecting said rst path, said conduit means including at least one passage extending substantially vtangentially into said discharge chamber for producing a vortex of the uid discharged from said second nozzle means, said tirst nozzle means discharging the charged material into said vortex to thereby atomize said material.

8. Apparatus of the character set forth in claim 7, in which said first nozzle means is of electrically insulating material.

9. Apparatus for coating objects with a supply of liquid coating material, comprising a nozzle head defining a first bore having an enlarged chamber adjacent one end thereof, said nozzle head including a wall portion between said enlarged chamber and said one end forming a restricted discharge outlet from said chamber, first nozzle means positioned in said first bore and having a second borek communicating with said supply of coating material for discharging material from said supply along a first path, saidv first nozzle means having a discharge end projecting into said outlet, means for electrostatically charging the material in said second bore, a source of gaseous fluid 'under pressure, and conduit means interconnecting said source of fluid and said enlarged chamber for admitting said fluid thereto, the wall portion of said nozzle head and the discharge end of said first nozzle means forming second nozzle means for discharging said fluid along a second path intersecting said first path at an acute angle, said conduit means including at least one passage extending substantially tangentially into said enlarged chamber for producing a vortex of the fluid dis'- charged from said second nozzle means, said first nozzle means discharging the charged material into said vortex to thereby atomize said material.

10.`Apparatus. forvcoating objects with a supply of liquid coating material, comprising a nozzle head defining a first bore having an enlarged cylindrical chamber adjacent one end thereof, said nozzle head including a wall portion having a circular edge between said enlarged chamber and said one end to form an outlet from said chamber, first nozzle means movably positioned in said first bore and having a second, coaxial bore communicating with said supply of coating material for discharging material from said supply along a first path, said first nozzle means including a discharge end projecting into the outlet formed by said circular edge, means for electrostatically charging the `material in said second bore, a source of gaseous fluid under pressure, conduit means interconnecting said source of fluid and said enlarged cylindrical chamber for admitting said fluid thereto, the wall portion of said nozzle head and the discharge end of said first nozzle means forming second nozzle means for discharging said fluid along a second path intersecting said first path, said first nozzle means discharging the charged material into said fluid to thereby atomize said material, and means for moving said first nozzle means in an axial direction with respect to said first bore to vary the rate of discharge of said fluid therefrom.

11. Apparatus for coating objects with a supply of liquid coating material, comprising a nozzle head defining a first bore having an enlarged cylindrical chamber adjacent one end thereof, said nozzle head including a wall portion tapering to a sharp circular edge between said enlarged chamber and said one end to form an outlet from said chamber` first nozzle means positioned in said first bore for axial movement with respect thereto and having a second ybore communicating with said supply of coating material for -discharging material from said supply along a first path, said first nozzle means including a tapered end projecting into the outlet formed by said sharp circular edge, the degree of taper of said tapered end being different from that of said wall portion, means for electrostatically charging the material in said second bore, a source of gaseous fluid under pressure, cond-uit means interconnecting said source of fluid and said enlarged cylindrical chamber for admitting said fluid thereto, the tapered wall portion of said nozzle head and the tapered end of said first nozzle means forming a second nozzle means for discharging said fluid along a second path intersecting said first path, said first nozzle means discharging the charged material into said fluid to thereby atomize said material, and means for moving said rst nozzle means in an axial direction with respect to said first bore to vary the rate of discharge of said fluid therefrom.

12, Electrostatic spraying apparatus for coating objects with a supply of liquid c-oating material, comprising a nozzle head defining a rst bore having an enlarged cylindrical chamber adjacent one end thereof, said nozzle head inclu-ding a wall portion tapering to a sharp circular edge between said enlarged cham-ber and said one end to form an outlet from said chamber, first nozzle' means positioned in said first 'bore for axial movement with respect thereto and having a secondbore communicating with said supply of coating material for discharging material from said supply along a first path, said first nozzle means having a tapered end projecting into the outlet formed by said sharp circular ed-ge and including an adjustable member movably disposed within said second bore for controlling the flow of material therethrough, the degree of taper of said tapered end being different from that of said wall portion, means for electrostatically charging the material in said second bore, a source of gaseous fluid under pressure, conduit rneans interconnecting said source and said enlarged cylindrical chamber for admitting said fluid thereto, the tapered wall portion of said nozzle head and the tapered end `of said first nozzle means .forming second nozzle means for discharging said fluid along a second path intersecting said first path, said first nozzle means dischargingthe charged material into said fluid tothereby atomize said material. and means mounted for rotation about the axis of said first bore and cooperating with said firstnozzle means for moving the same in an axial direction with-respect to said first bore, to adjust the size of the outlet between said tapered end and said wall portion and thereby vary the rate of discharge of said fluid therefrom.

13. Apparatus for coating .objects with a supply of coating material, comprising a nozzle head defining a first .bore having an enlarged cylindrical chamber adjacent .one end thereof, said nozzle head including a wall portion having a sharp circular edge between said enlarged chamber and said one end to form an outlet from said chamber, first nozzle means movably positioned in said first bore and having a second bore communicating with said supply of coating material for discharging material from said supply along a first path, said first nozzle means having ya discharge end projecting into the o-utlet formed -by said sharp circular edge, means for electrostatically charging the material in said second 'bore to a high D.C. potential, a source of fluid under pressure, conduit means interconnecting said source of fluid and said enlarged cylindrical chamber for admitting said fluid thereto, the tapered Wall portion of said nozzle head and the discharge end of said first nozzle means for-ming second nozzle means for discharging said fluid along a second path intersecting said first path, said conduit means including a plurality of passages extending substantially tangentially into said enlarged cylindrical chamber for producing a vortex of the fluid discharged from said second nozzle means, said first nozzle means discharging the charged material into said vortex to thereby atomize said material, and means for moving said first nozzle means in an axial direction with respect to said first bore to Vary the rate of discharge of said fluid therefrom.

14. Electrostatic spraying -apparatus for coating objects with a supply of liquid coating material, comprising a nozzle head defining a first bore having an enlarged cylindrical chamber adjacent one end thereof, said nozzle head including a wall portion tapering to a sharp circular edge between said enlarged chamber ,and said one end to form -an outlet from said chamber, firs-t nozzle means positioned in said first bore for axial movement with respect thereto and having a second bore communicating with said supply -of coating material for discharging material from said supply along a first path, said first nozzle means having a tapered end projecting into the outlet formed by said sharp circular edge, the degree of taper of said tapered end being different from that of said wall portion, means for electrostatically charging the material in said second bore to a high D.C. potential, a source of gaseous fluid under pressure, conduit means interconnecting said source of fiuid and said enlarged cylindrical chamber for admitting said fluid thereto, the tapered wall portion of said nozzle head and the tapered end of said first nozzle means forming second nozzle means for discharging said fluid along a second path intersecting said first path, said conduit means including a plurality of passages extending substantially tangentially into said enlarged cylindrical chamber for producing a Vortex of the fiuid discharged from said second nozzle means, said first nozzle means Vdischarging the charged material int-o said vortex to thereby Vatomize said material, and adjustment means mounted for rotation about the axis of said first bore and cooperating with said first nozzle means for moving the same in `an axial direction with respect to said first bore, to adjust the size of the out-let between said tapered end and said wall portion and thereby vary the rate of discharge of said uid therefrom.

15. Electrostatic spraying apparatus of the character set forth in claim 14, in which said nozzle head comprises an elongated housing having a rear wall at the end thereof opposite said wall portion, said first nozzle means including an abutment disposed within said housing, and resilient means compressed between said abutment and said rear wall for resisting rearward movement of said first nozzle means relative to said rea-r wall. K

16. Apparatus for coating objects with a supply of liquid coating material, comprising a nozzle head defining a rst bore having an enlarged cylindrical chamber adjacent one end thereof, said nozzle lhead including a wall A portion tapering to a sharp circular edge between said enlarged chamber and said one end to form an outlet from said chamber, first nozzle means positioned in said first bore for 'axial movement with respect thereto, said first nozzle means having a second bore communicating with said supply of coating material and incl-ud-ing a conical opening for discharging material from said supply along a first path, said first nozzle means having a tapered end projecting into the outlet formed by said sharp-circular edge .and including an elongated pin member movably disposed within said second bore, the degree of taper of said tapered end being different from that of said wall portion, said pin member having a conical head positioned within said conical opening for controlling the flow of material therethrough, means for electrostaticallycharging the material in said second bore, a source of gaseous iiuid under pressure, conduit means interconnecting said source of fluid and said enlarged cylindrical chamber for admitting said uid thereto, the tapered wall portion of said nozzle head and the tapered end of said first nozzle means forming second nozzle means for discharging said fluid along a second path intersecting said first path at an acute angle, said conduit means including a plurality of passages extending substantially tangentially into said enlarged cylindrical chamber for producing a vortex of the fluid discharged from said second nozzle means, said first nozzle means discharging the charged material into said vortex to thereby atomize said material, and means mounted for rotationabout the axis of sai-d first bore and cooperating with said first nozzle means for moving the same in an axial'direction with respect to said first =bore,.to adjust the size of the outlet between said tapered end and said wall portion and thereby vary the rate of discharge of said uid therefrom.

References Cited by the Examiner UNITED STATES PATENTS 2,302,185 11/1942 Campbell Z39-15 2,302,289 11/ 1942 Bramston-Cook 239-15 2,766,064 10/1956 Schweitzer 239-15 3,039,696 6/1962 Point et al. l Y 239-15 3,056,557 10/1962 Walberg Z39-l5 3,057,558 10/1962 Verba et al 239-15 3,059,613 10/1962 Nakaya 239-15 3,065,106 11/1962 Rhodes 239-15 i 3,077,857 2/1963 klidner 239-15 i 3,082,956 3/1963 Point 239-15 3,111,266 11/1963 Axelson et al. 239-15 M. HENSON WOOD, JR., Primary Examiner;

EVERETT W. KIRBY, Examiner.

Claims

1. ELECTROSTATIC SPRAYING APPARATUS, COMPRISING A SUPPLY OF COATING MATERIAL, FIRST NOZZLE MEANS COMMUNICATING WITH SAID SUPPLY FOR DISCHARGING PARTICLES OF SAID MATERIAL ALONG A FIRST PATH, SAID FIRST NOZZLE MEANS INCLUDING MEANS FOR DIRECTING THE INDIVIDUAL PARTICLES OF SAID MATERIAL IN SUBSTANTIALLY LINEAR DIRECTIONS ALONG SAID FIRST PATH, MEANS FOR ELECTROSTATICALLY CHARGING SAID MATERIAL PRIOR TO ITS DISCHARGE FROM SAID FIRST NOZZLE MEANS, A SOURCE OF FLUID UNDER PRESSURE, AND SECOND NOZZLE MEANS CONNECTED TO SAID SOURCE FOR PRODUCING A VORTEX OF SAID FLUID AND FOR DISCHARGING SAID VORTEX ALONG A SECOND PATH INTERSECTING SAID FIRST PATH, SAID FIRST NOZZLE MEANS DISCHARGING THE LINEARLY MOVING PARTICLES OF MATERIAL INTO SAID VORTEX TO THEREBY ATOMIZE SAID MATERIAL.