US2196647A

US2196647A - Material fusing and projecting apparatus

Info

Publication number: US2196647A
Application number: US77768A
Authority: US
Inventors: Aulden D Snyder; Albert F Maier
Original assignee: WILLIAM J WESSELER
Current assignee: WILLIAM J WESSELER
Priority date: 1932-03-24
Filing date: 1936-05-04
Publication date: 1940-04-09
Anticipated expiration: 1957-04-09

Description

April 9, 1940. A. D. sNYDER E1- AL IATERIAL FUSING AND PROJECTING APPARATUS Uriginal Filed March 24, 1932 5 Sheets-Sheet 1 INVENTORS A RNEY.

April 9, 1940. A. D. sNYDER ET A1.

UATERIAL FUSING AND PROJECTING APPARATUS Original Filed March 24, 1932 5 Sheets-Sheet 2 v E n NM m 32 S H n E n 2 .NN E .3 ww uw *u uw www-@ag Hill/521mm BY am @13505 5:9123

ORNEY.

April 9, 1940. A. D. sNYDER n AL IATERIAL FUSING AND PROJECTING APPARATUS' Original Filed March 24, 1932 5 Sheets-Sheet 3 IVENTRS MMV @l 6W BY ms mwf'eaz ORNEY.

APF 9, 1940- A, D. sNYDER Er AL 2,195.64?

MATERIAL FUSING AND PROJECTING APPARATUS Original Filed March 24, 1932 5 Sheets-Sheet 4 INVENTORS emma Ap. s, 1940 UNITED STATES PATENT OFFICE MATERIAL FUSING AND PBOJECTING ABATUS Original application March 24, 1932, Serial No. 600,952. Divided and this application May 4,

1936, Serial No. '17,768

Schirm.

This invention. as indicated. relates to a materia! fusing and projecting apparatus, and is a division of our application Serial No. 000,952. filed March 24. i932. More particularly. it coma prlsesanapparatushavingspecialmeansfor Another object of the invention is to provide meanstoentrain andproiectfusedparticlesand assistinbreakingthem upintoiinely divided elements and depositing them in intimate associationwiththepariiclesonthesurface tobecoated without interfering with the uniformity of the arcandtheevensupplyingofthematerialtobe fused.

Anotherobjectoftheinventionistoprovidea so hollow electrode for a spraying apparatus.

Another object of the invenhon is to provide an electrode having a plurality of passageways extending longitudinally thereof.V

Another object of the invention is to provide a 5| sprayapparatusadaptedtousepulverindmaterial to be fused and means for projecting the same into an arc and thence the fused material against the surface to be coated.

Another object of the invention ls to provide an electrodeintheform of awiretobefusedand 5 a second electrode in the form of a hollow carbon surrounding the iirst electrode with proper insulation thereinbetween. whereby the thickness of the insulating medium would determine the minimum spacing of the electrodes. l0

Another object of the invention is to provide anarcofthecharacterjustdescribedhaving around its periphery a pressure Jet adapted to produce an area of reduced pressure adjacent sus am, whereby to induce the fused particles l Atoentersuchcurrentandheprollectedontoa.

surface. v

Another object of the invention is to provide a latitude of control for the feeding means for tnewlreeleetroae so um acnmgeormaterlai 0 maybereadilyprovidedandchangeofspeedin feeding the same.

Another object of the invention is to provide improved means for setting up the arc which lteansmayberemovedtoapodtionfreeofthe s Another object of the invention is to provide a light. compact spraying apparatus which may be readily handled by the operator and may be ada0 justedforspeedofthematerislsuppiyandthe quantity of heat at the fusing point.

Another obiectof the invention is to provide an apparatus wherein the motor drive for the material supply is independently supported and 35 carriedtothepointofapplicationofpower through a flexible drive shaft.

Another object of the invention is to provide a pair of independent material fusing nozzles fed by drive mechanism preferably actuated by 0 a single prime mover and adapted to supply fusedmaterialfromaphxralityofmaterialsupplies of the same or varying character which may be intermixed, if desired. at the meeting point of the respective jets.

Another object of the invention is to provide a plurality of nomles parallelly arranged or angularly related to each other.

Another object of the invention is to provide spraying apparatus with magnetic means for disdo placing the arc toward a predetermined position.

. Another object of the invention is to provide an apparatus for applying to material to be fused a degree of ht of sumcient intensity to impart u to the fused material a state of free molecular activity.

Other and further objects of the invention will appear in the course of the following description.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means andpmethod hereinafter fully described and particularly pointed out in the claims, the annexed drawings and the following description setting forth in detail certain mechanism and steps embodying the invention, such dis closed means constituting, however, but several of various mechanical forms in which the principle of the invention may be used.

In said annexed drawings:

Figure 1 is a side elevation partly in section showing one form of apparatus embodying the principles of the invention;

Figure 2 is a transverse vertical sectional view through a portion of the nozzle shown in Figure 1;

Figure 3 is a top plan view of the apparatus shown in Figure 1 with the cover section thereof removed;

Figure 4 is a detail view in the form of an end elevation partly in section of a portion of the drive mechanism for the fusing wire supply;

Figure 5 is a sectional view showing a modified form of apparatus wherein the wire to be fused comprising one electrode is fed at an angle to the air jet member embodying another electrode;

Figure 6 is a side elevation of an apparatus wherein the motor drive to the wire feeding apparatus is carried through a flexible shaft from the xed position of the motor at an adjacent point;

Figure 7 is a top plan view of an apparatus with the cover section removed illustrating a multiple nozzle with wire feeding means actuated from a single power source and independently adjustable as to each wire;

Figure 8 is an enlarged detail view partly in section illustrating a modified form of arcinitiating device;

Figure 9 is a central longitudinal sectional view of a modified form of apparatus wherein a nozzle shell is provided adapted to concentrate the pressure jet around the fusing point of the material;

Figure iC- is e, view partly in section showing another modified form of spray gun construction; and

Figure 1l is a 'view of a double nozzle spray ap paratus, said nozzles having individual features of construction.

As is clearly shown in Figures l and 3, the preferred form of apparatus comprises a casing I within which the wire feeding mechanism is mounted, said casing being secured to the end plate of a motor housing 2 having a worm shaft 3 extending upwardly at a central point.

A side bracket 4 is secured to the motor housing and a handle 5 is secured to the outer end of said bracket whereby the apparatus may be carried by the operator when in use. At the forward end of the wire feeding casing the nozzle section of the apparatus is provided.

The motor shown in this apparatus comprises an electric motor, although where desired an air motor in the form of a Pelton wheel or the like may be used. The shaft 3 of the electric motor engages a worm wheel 6 operating a transverse shaft 1 carrying a worm 8 and in turn driving a worm wheel 9 on a transverse shaft II carrying a resiliently supported friction disc I2 at the end thereof. Said disc preferably is formed with a hub I3 at its rearward end splined to the shaft and held at its outward limit of motion by a coil spring I4 about the shaft bearing against a fixed collar Il at a central point on the shaft. The means for feeding the wire comprises a feeding wheel I3 with minute teeth between two flanges of a size to guide the wire and prevent lateral displacement and to receive within the same an idler wheel I1 carried on a hinge cover I3 at the top of the casing. Said idler wheel is mounted on a bracket I3 carried on a spring member 2| and an adjusting screw 22 with a knurled head is mounted adjacent the free end of the spring to apply any desired degree of pressure to cause said wire to engage the toothed portion of the driving wheel. The feeding wheel I3 is mounted on a shaft 23 supported at its ends in bracket members 24 secured to the base of the casing and has adjacent thereto a current conducting wheel 25 adapted to be energized by sliding contact with a spring terminal member 23 to carry one portion of the electric circuit to the wire 2T. The wire is received through an aperture in the rearward end of the casing suitably insulated from the casing and the brackets and other mechanism of the drive are also suitably insulated from the lcasing. A funnel-shaped sleeve 23 is engaged in the aperture through which the wire enters the casing to assist in guiding the same to the feeding position.

The means for transferring power from the driving`disc I2 to the feeding wheel I6 for the wire comprises a non-conducting friction wheel 3| splined upon the feed wheel shaft 23 and adapted to be shifted transversely across the face of the driving disc by means of a shifting yoke 32 formed in two parts and engaged upon opposite sides of said friction wheel and adapted to be moved transversely of the driving disc by means of an adjusting screw 33 rotatably secured in a. block 34 adjacent the lower end of the casing through engagement of a collar 35 on said screw shaft within a recess in the supporting block mounted in the casing wall, wherein an enlarge the worms and worm wheels, and in the size of y the friction disc 3| with reference to the driving disc |2, may be varied in accordance with the character of the material to be fed in the form of wire, or the like, as well as the thickness of the wire and the quantity of heat which may be required for the particular work in hand.

The casing for the wire feeding mechanism may be secured by a series of screws 4| engaged through internal lugs 42 formed on the casing and held in position over the top of the motor casing in insulated relation thereto by means of suitable insulating sleeves 43, washers 44 and a gasket 45, the lower ends of said screws entering screwthreaded apertures in alignment therewith.

`The upper portion of the casing carrying the The snap spring I engagesaproiectiontlonarearwardwallofthe casing 'lhe forward wall of the casing is formed with an enlargement adapted to provide a passageway ll for the air or other gas wed to project the fused material from the nossle and preferably is provided with a nipple Il. screw-threadedly engaged in' a socket below said passagewav to receive the air hose. The wire is preferably received at its forward end in a sleeve I8 formed of porcelain or other insulating material having a central aperture slightly larger than the sise of the wire, said sleeve being mounted at its rearwardendinapairofclampingdiscs, .centrally apertured and compressing a disc 5l of compressible gasket material intermediate the same to form an airtight joint. The insulating sleeve I3 is received within a tubular member Il preferably of carbon forming the other electrode of the circuit. said sleeve preferably extending in a forward direction, and being positioned so as not to extend to the extreme end of the electrode, thus permitting the flexing of the wire to initiate the arc and also establishing a substantially uniform distance between the electrodes once the arc is initiated.

The electrode l1. as is clearly shown in Figure 2, is formed with a large number of small air passageways Il extending longitudinally thereof sothataiargeamountofairorgasmaybecarriedtoapointexternallydistributedaboutthe arc. The electrode is supported in a collar Il screw-threadedly engaged in a recess formed in the front wall of the casing concentricaily with thepositionof thewireandisrmiyclampedin air-tightrelationtothecasingbymeansofan insulating disc Il engaged about the electrode l1 withinthecollarilwhichisprovidedwitharecem ctainim a compressible member l! beneath a portion of which an annular insulating member is provided. said member being engagedwithintherearwardopeningofthecollar andbearingagainstthefrontwallofthecasing. AnexternalsleevelIisalsoscrew-threadedlysecuredtothecollar.saidsleevebeinginspaced relationtotheelectrodeandhavingapluralityoi Ventilating apertures Il therethrough. Said sleeve is provided. preferably on its under side. with an opening to receive a current conducting member Il insulated from the sleeve by means of abushingll. ssidconductormemberbeingconnected with a ring I8 frictionally engaged over said electrode and completing the circuit therethrough. Asuitableterminalllisprovided on the end of the member Il for attaching a flexible conductor.

At the forward upper end of the cylindrical sleeve t4 an arc initiating arm Il is provided, said armbcingcarriedonashaft 12 iournaledina pair of brackets 13 secured to the upper forward end of the sleeve and having a handle 1I at the outer end of the shaft for swinging the arm downwardly into contact with the wire 21. The arm has Aa Y-shaped terminal 'Il which rides against the wire and deiiects it a sumcient degree tc indicate the arc through contact of the wire with the electrode. after which the release of the operating member will permit the arm to be swung upwardly through the action of a coiled spring 1l engaged about the shaft and having one end secured thereto and its opposite end secured to the supporting bracket.

The modified form of apparatus shown in Figure 5 discloses substantially the same feeding mechanism as that heretofore described, but the wireinsteadofbeing fedthroughthehollow electrode is fed preferably at a right angle thereto through a fixed sleeve Il. The hollow electrode nisengagedthroughanapertureinanextension 83 on the casing It and is held in clamped relation thereto by means of a collar Il compressing an annular comprensible disc It thereon. An enclosing tube Il for the rearward portion of the electrode is screw-threadedly engaged in said extemion Il and an enclosing tube Il for the forwardendoftheelectrodeisengagedonanannular flange on the extension I3 extending about the electrode. Ihe rearward end of the electrode is provided with a reducing coupling Il within the smaller end of which is engaged an air line t! toasourceofcompressedairsupplysothata projecting air iet of adequate volume may be carried through the central aperture Il of the electrode to a point adjacent the point of formation of the arc. Ihe motor for driving the apparatus shownini'lguremaycorrespondtothatillustratedinl'lgureLorthemotorMmaybe connected by means of a flexible shaft Il with a shaft carryingthe dr'ivingworm for the first reducing worm wheel. as is shown in Figure- 6.

lhe air or gas which is brought in through the hollow electrode passes along side of the arc and tersect the arc. This close positioning of the jet tothearcisdesirableinorderthatfusedmaterialmaybeentrainedinthejetandcarrledto thesurfaceto be coated without disrupting the arc.

Inbothofthetypesofconstnictionalready described. either direct or alternating current maybeused,butthedirectcurrentarcispref erableforthereasonthatthewiretobefused maybemadetheanodeandthusreceivethe beneilt of the high heat generated at the anode andalsoredueethewearingawayoftnehcllow eiectrodewhichwnuldbethecathode. Theuse ofdirectcurrentalsohastheadvantageofcontinuity of the arc. It is known that the greatest wearingawayoccursattheanodeindirectcurrent arcs. and this natural function of the arc is used to enhance the heating effect upon the wire.

Anothertypeofsprayglmisilltratedinl'lgure'I, whereintwowiresareprojected angularly towardeachotherorparalleltoeachothenas may be desired. by means of separate drives actuated in this instance by a single prime mover driving a worm shaft lli. This shaft engages two worm wheels in, lll, one connected with a friction drive for one of the wires I, and the other connected with a friction drive for the otherl wire Ill, and said friction drives having the regulating mechanism heretofore described in connection with the single wire feed. As is clearly shown in Figure 7, the drives for the separatewiresarearrangedsothatthefeed wheels operate in the same direction and make possible a very convenient disposition of the friction drive discs and the control means for the rate of sneed.

Where wire of the same size and character is to be used in each'of the paired or duplex nzles shown in Figure '7. the rate of feed would be uniform and it would be possible to provide a pair of feed wheels on a single shaft, particularly where such nozzles were arranged in paralle] relation. Where an angular arrangement is desired, as illustrated in Figure 7, the provision of a single prime mover driving two friction discs set at an angle., permits the use of two angularly disposed feed wheels and this in turn permits independent control of speed. This latter feature in very close proximity thereto, but does not intherefore gives greater flexibility of control and where it is desired to spray material of diiIerent composition from each nozzle, it may be found that a high rate of feed would be necessary in one nozzle as compared with the other to produce the desired effect on the coated surface. It is pointed out in this connection that a twin nozzle spraying apparatus of this type is adapted for the laying of a preliminary coating on the surface directly in advance of the finishing coating and before the first coatinghas had an opportunity to become oxidized owing to the close succession in which the coatings are applied. The arrangement also would permit the mixture of the fused material in the jets and the deposition of an alloyed or mixed coating upon the surface to secure certain predetermined effects. For certain work divergent nozzles may be found desirable and the apparatus may be formed so as to permit any desired angular relation of the nozzles. Likewise any desired number of nozzles may be provided for special uses.

One form of device for initiating the arc is illustrated in Figure 8, wherein a plunger |06 having a Y-notch |01 at its lower end is normally held retracted out of the path of the jet by means of a spring |08 bearing against a bushing |09 engaged in the wall of the sleeve about the nozzle and at its opposite end against the terminal knob ||2 on the plunger so as to maintain the lower end against the innerface of said sleeve. The arc is initiated by pressing upon the terminal, causing the Y-shaped or notched lower end of the plunger to engage against the wire 3 and deflect it out of its normal axial position within the nozzle until it contacts with the adjacent electrode ||4 surrounding the insulating guide tube ||5 for the wire.

Suitable adjustment for the distance the electrode projects beyond the insulating sleeve for the wire may be provided, but for immediate adjustment to compensate for the burning away of the electrode, the sleeve is supported telescopically over an inner sleeve ||6, being held thereon by means of a set screw |1 or any other convenient securing means, whereby the outer sleeve may be moved toward the free end of the carbon electrode so as to bring the plunger into a suitable position to initiate the arc.

The electrode shown in Figure 8 corresponds with that shown in Figure 1 of the drawings, and the type of arc initiating plunger may be applied to an apparatus of the character shown in Figure 1 wherein a telescopic outer sleeve carrying the arc initiating device would be substituted for the oscillating arc initiating device shown in Figures 1 and 3.

Another form of nozzle is illustrated in Figure 9 wherein the air or other material projecting medium is carried to a point adjacent the arc within an annular space ||8 intermediate the outer shell ||9 and the electrode |2|. In such case the electrode is not formed with a series of apertures through which the air or gas supply is projected, but is formed with only the central apertures |22 adapted to receive the insulating tube |23 carrying the wire |24. The electrode is supported within a sleeve |25 within the rearward portion of the nozzle shell and secured therein by any suitable means shown as a screwthreaded engagement of a rearward flange on the sleeve with a screw-threaded recess in the base of the nozzle shell, immediately in advance of a shallow member |26 at the base of the nozzle shell through which the air or other projecting medium utilized may be admitted to the annular space ||3 between the shell and the electrode. The supporting sleeve for the electrode may be insulated therefrom by means of an inner sleeve of insulating material |21, the supporting sleeve being secured thereto by means of suitable set screws |23 intermediate the supporting and spacing flanges or projections on the supporting sleeve. The current is carried to the hollow electrode by means of a conducting element |29 engaged through an insulating bushing |3I secured in one side of the nozzle shell, preferably at a central position, the terminal of said conductor being shown in the form of a band |32 encircling the electrode.

The base |33 of the nozzle shell may be externally screw-threaded so as to be engaged with- `ln the screw-threaded flange |33 formed on the outer face of the casing and it is obvious that other types and sizes of nozzles may be readily substituted on the apparatus by merely unscrewing the nozzle shell from the front of the casing and substituting the desired type of nozzle shell in lieu thereof. r

The arc initiating device illustrated in Figure 9 comprises a lever |35 supported on a pivot |36 mounted centrally of the upper side of the nozzle having an operating button |31 adjacent its rearward end and having a depending link |38 at its forward end apertured adjacent its lower end to engage over the wire preliminary to the initiating of the arc. When the arc is desired the button is pressed downwardly and the wire will then be drawn upwardly into contact with the adjacent electrode and the fusing of the metal will take place at a point immediately within the outer end of the nozzle shell.

The outer end of the nozzle shell as clearly shown in Figure 9, overhangs the electrode to a slight extent and is tapered toward its free end so as to concentrate the air supply or other means utilized to project the material in the form of a gaseous cone enveloping the arc.

The overhanging of the outer end of the nozzle shell has the advantage of screening or shielding the arc from thc eyes of the operator so as to make unnecessary the use of a welding hood or protective glasses over the eyes of the operator to prevent injury to the eyes from the ultra-violet rays of the arc. It also has the effect of providing a large quantity of rapidly moving air or gas about the arc so that no undue heating effect will take place on the outer end of the nozzle shell.

The arc initiating link in the form shown in Figure 9 may be provided with a coiled spring around its pivot pin to throw the link upwardly out of the path of the spray material after the arc has been initiated or the link may be manually moved to an inoperative position. Likewise a telescopic mounting for the outer end of the nozzle shell may be employed similar to that shown in Figure 8.

Another form of construction is illustrated in Figure 10, wherein a wire electrode |82 is fed through an insulating sleeve |83 toward a fixed electrode |84 in the form of a carbon block having a central aperture |85 into which the wire may pass. An air supply nozzle |86 is positioned preferably at right angles to the position of the wire. Means similar to the devices heretofore described may be provided to deflect the wire sideways into the contact with the carbon electrode and thus initiate the arc. The air jet does not intersect the arc after it is initiated and the quantity of air delivered through such jet must siii besuilicientataiitimestocarrythemoltenmaterial with suillcient velocity Klimt the surface tobecoatedtoinsureclosecontactofthemolten and penetration of the superncial area thereof. Inthelast-nameddevicetheelectrode iMis ofthedisc 2li screw-threadedly engaged within the ange 2li. The conical outer shell 2M of the guide member is screw-threadedly engaged within the flange lll and at its forward end extendstoapositioncloselyadjacenttheholiow insulatingsleevejustreferredto.

The insulating sleeve may be formed with a series of longitudinallyV extending air passagewavs 2|! which would serve to admit the air trom a chamber 2li 4within the base 205 and dischargethesamearoundthepathofthearc. Thuseachofthewireelectrodeswillemerge angularly fromits supporting device and will meet and contact at a position slightly in advanceofthefreeendsofthesupporting andabouteachofsaidwiresaconeofsiror like projecting fluid will be disposed with but a verysmallportionofsuchairintersectingthe pathofthearc.

It may be found that it would be desirable to combine some of the features of one type of ap- 'lli paratus illustrated with certain features from another type of apparatus and such combinations may be freely arranged for in accordance with the work to be accomplished by the apparatus.

The advantages of the several constructions above described have already been partly indicated, but it should be emphasized that the chief advantage in using the electric arc in place of anyothermeansoffusingthematerialtobe sprayed consists in the almost unlimited degree of heat which can be obtained through the arc and the consequent wide variety of materials which can be fused and deposited in such fused form upon a surface to be coated.

The adherence of the particles projected from the point o f fusion against the surface is very largely dependent upon the degree of heat originally applied to bring about the fusion of such particles inasmuch as .the molecules of the material are disrupted by the intensity of the heat so that the material is in a somewhat free molecular condition when it impinges upon the surface to be coated and interknits with the irregularities of the surface into such close union that it cannot thereafter be ted along a plane of cleavage, but is permanently connected with such surface.

apparatmabovedescribemitispomibletouse various mterials which when fused would become enamels whichcould thus be deposited directly upon the surface of articles to be enameled and provide a smooth and satisfactoryv surface without requiring extended baking and heat treatment operations preliminary tothe completion of such articles.

Othermodesofapplyinltheprincipleofour invention may be employed instead of the one explained, change being made as regards the herein disclosed, provided the means statedbyanyofthefollowingclaimsorthe equivalent of such stated means be employed.

We therefore particularly point out and distinctly claim as our invention:

l. An apparatus for fusing and spraying material having in combination a pair of supports. electrodes in concentric relation engaged in said supports, clamping means for spacing said electrodes to provide an arc, and means operating through said respective electrode supports for feeding fusible material to said arc and for projecting the material fused in said arc, said means being externally tangential to the positive co1- umn of said arc. A

2. A metal spray apparatus having in combination a nozzle, an electrode formed of fusible wire positioned centrally of the nozzle, a second electrode positioned concentrically about said flrst electrode and in spaced relation thereto to provide an arc, an apertured member for adjustably supporting said second electrode, compressible clamping means, providing for longitudinal movement, for positioning the end of said second electrode in operative relation to its companion electrode, insulating means interposed between said electrodes, and means disposed concentrically about said are and externally tangential to the positive column of said arc, to project the material fused in said arc against a surface to be coated.

3. A metal spray apparatus having in combination a nozzle. an electrode formed of fusible wire positioned centrally of the nozzle, a second electrode positioned concentrically about said rst electrode in spaced relation to provide an arc, an apertured member for adjustably supporting said second electrode, compressible clamping means, providing for longitudinal movement for positioning the end of said second electrode in operative relation to its companion electrode, a sleeve of insulating material interposed between said electrodes and extending to a point spaced inwardly from the free ends thereof, means for feeding said fusible electrode, and means positioned outwardly of said sleeve for forcibly projecting a gaseous jet adjacent the arc and externally tangential to the positive column of said arc between sald electrodes to carry material fused in said arc against a surface to be coated.

4. A metal spray apparatus having in combination a hollow electrode, means for adjustably supporting said electrode, means for positioning the end of said electrode in operative relation to a companion electrode, a second electrode in spaced relation to said hollow electrode to provide an arc and formed of wire to be fused in the arc, means for feeding said electrode wire toward the end of the hollow electrode, and means for supplying a gaseous iet through said hollow electrode externally tangential to the positive column of said arc to project the fused material against the surface to be coated.

5. A metal spray apparatus having in combination a central fusible electrode wire, an insulating sleeve surrounding said wire, a tubular electrode surrounding said sleeve, means for adjustably supporting said tubular electrode, means for positioning the end of said tubular electrode in operative relation to the end of said fusible electrode wire, means connecting said electrodes to supply fusing current thereto. means for feeding said central fusible electrode wire outwardly past the ends of said sleeve and electrode, another sleeve in spaced relation to said electrode providing a gas passageway around said electrode, and means for directing said gas inwardly externally tangential to the positive column of the arc to cause fusible metal particles to be engaged in said gas stream and projected against the surface to be coated.

AULDEN D. SN'YDER. ALBERT F. MAIER.