US2207765A - Metal spray apparatus - Google Patents

Description

July 16, 1940. w.- H. STEVENS METAL SKPRAY APPARATUS Filed July e, 1957 4 INV NToR.

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ma u n N s mne 1N Patented July 16, 1940 UNITED STATE-s PATENT oFl-lcE 2,207,765 I METAL sm! APPARATUS i William H. Stevens, San Francisco, Calii'. Application July 6,' 1937, Serial No. 152,092 'z ohms. (cl. :i1-liz) This invention relates to a metal spray apparatus, commonly known as a metal'spray gun, and particularly to the nozzle portion thereof,

whereby metal in the form of wire is fused or melted and then atomized and projected againstl a surface to be coated.

The object of the present invention is to generally improve and simplify apparatus of the character described; to provide a nozzle having a wire guide therein, said guide being readily removable and interchangeable to accommodate wire of varying size or gauge; to provide a wire guide, one end of which supports a groovedv plug which seats in the nozzle and cooperates therewith to iorm a plurality of gas discharge orifices, said wire guide, plug, and nozzle being separable and removable to permit cleaning ofthe grooves or es formed in the plug; to provide a nozzle having an interior burning nozzle, a head therefor, and within the burning nozzle a wire guide; to provide a common seat in the head for the reception of the inner end of the burner nozzle and the innerv end of the wire guide; to provide a seat in the outer endof the burner nozzle for the reception of a groov'ed plug: to Provide a'. spring within the burner nozzle to force the plug and the wire guidev against their respective seats;

to provide a screw connection between the burner nome andthe head, whereby thespring is compressed and the burner nome is connected to the head; to provide a cooperating burner and air nozzle, in which the air nozzle is provided with a plurality of airpassages disposed on varying angles to cause a portion of the air toatomize the molten metal, and other portions of the airvto direct andfconilne the atomized metal as it is being discharged: and further to provide a nozzle of the character described having a main and ,ay secondary .burner nozzle, in which the secondary nozzleisutilized to preheat the metal wire .before it reaches the main burner nozzle, and the waste heat from the secondary burner vnozzle .is used to heat the air employed to atomlze the molten metal. l The nozzle is shown by wawy of illustration in the, accompanying drawing, in Fig. 1 1s a. central, v erueai, longitudinal sectiony of the nozzle, said section showing an intermediate head to permit preheating of the wire and heating of the air applied forthe -atomization of the metal;

-Fig.2isanendviewofthe nozzle;

Fig, 3l is a cross section taken'on line III-lill of Fig. 1; A

Fig. 4 is la cross section taken on line IV-IV of Fig.'1; A

Fig. 5 is a section similar to Fig.1, but showing the intermediate head removed.

Fig. l6 is a perspective view of the inner tapered nozzle plug.`

Referring to the drawing in detail, and particularly to Fig. 5, A indicates a head member of suitable construction, in which is formed an interior cone-shaped seat 2, and on the exterior, threaded connections 3 and 4. A threaded opening 5 centrally disposed with relation to the seat is also formed in the head, and screwed into the same is a tube 9 which forms a preliminary wire guide as will hereinafter'be described.

i Disposed centrally of*4 the nozzle asa whole is a main wire guide 1 and surrounding the same is a burner tube 8, an air tube 9, and a nozzle head I0. The main wire guide is tubular and elongated, as shown, and its inner end is enlarged and tapered as shown at I4 to seat in the inner end of theficone-shaped seat 2. The outer end 'of the wire guide is reduced in diameter as at I5, and is provided with an annular shoulder I6. Slidably mounted in the outer or reduced end of the wire guide is a tapered plug I1, 'the outerl surface of which is provided with a series-.of grooves which, together with the outer end of the burner tube 8, form a plurality of gas-discharging orices I9. 'I'he outer end' of the burner tube is tapered and provided with Aan in Yterior seat to receive the plug. A spring I9 is interposedbetween a shoulder formed in the inner end of the plug and the shoulder I6, and the spring exerts suicient presure to maintain the inner end of the wire guide and'the outer end of the plug in engagement with their respective seats, the pressure being sumcient to prevent gas leakage. The burner tube 8 'is larger in diameter than the wire guide 1, and an annular chamber is thus formed between them, as indicated at I9, into which :gas is delivered through a passage 29, the gas delivered being a mixture of oxygen Aand hydrogen or the like.J The inner end of the burner tube 8 is enlarged inamanner similar. to the inner end of the wire guide, and it is tapered to engage and iit the outer end of the cone-shaped seat 2. A nut 3a engages .the thread '3, and when this nut is tightened, it forces the tapered inner end of the burner tube into the seat and at the same time increases the lpressure of the spring I9, to insure proper seating of the plug and the inner end of the wire guide.

The burner tube I, as previously stated, is surrounded by an exterior air tube 9. 'Ihis is larger in diameter than the burner tube, and an annular chamber 22 is thus formed into which air is interposed, under comparatively high pressure, through a passage indicated by dotted lines at 23. The air tube is secured to the head by the screw connection indicated at 4. The outer end of the air tube is threaded as shown at 23, and the nozzle I0 is screwed in at this point. This nozzle is tapered in the interior to set against the outer end of the burner tube. The outer tapering face of this tube is grooved in a manner similar to the plug, anda plurality of'l discharge orifices or passages are thus formed as indicated at 24, to which air under comparatively high pressure discharges. This air is utilized for the purpose of atoniizing and projecting the molten metal, and if these passages alone were used,

f the metal would be rapidly dispersed and spread over a comparativelyv large area. This is not desirable, and means accordingly have been providedfor conning the spray as much as possible. This is accomplished by forming a second series of discharge orifices in the nozzle I0 as indicated at 25. These are disposed on a less angle than the orces 24, and as such cause the air' discharged to converge at a point'avconsiderable distance in front of the nozzle, and thus serve to confine the molten spray to the area desired. That is, the air discharging through the orifices 2d, and which functions to atomize the molten metal, will converse for instance at the point indicated at 30 in Fig. 1, while the air discharging through the orices or passages 25 will converge at a point 3l and as it does so, it `'will obviously serve to assistin .confining the spread of the atomized metal.

Where a metal wire having a comparatively low melting point is being used, for instance Fig. 1.

33' adapted to t the seat 2 formed inthe head ,1

aluminum wire or tin, etc., preheating of the wire before it reaches the main burner nozzle, to Wit, the flame produced by the gas discharging through the orices I8, is not required, but when a metal wire is being employed which has a comparatively high melting point, for instance steel wire, and particularly steel wire of a high carbon content, better results are obtained if the wire maybe preheated before reaching the main burner nozzle. To accomplish this, an intermediate head may be employed as shown at B in This head is provided with a tapered end A, and it is secured therein by a threaded extension 34 and a nut 35. The intermediate head is fairly longand its opposite endv is provided with a-cone-,shaped seat 2a similar to the seat 2, this seat being provided for the reception of the inner end of the burner tube 8 and the rinner end of the wire guide 1. The gas from the burner tube is delivered from the head through a passage 20a which is connected with an annular passage 20h; this in turn connects with a plurality of passages 20c formed in the intermediatlhead, and'these in turn connect with the annular chamber i9 formed between the main wire guide and the burner tube 8. The intermediate head is also secured to the main head A by means of a nut 40 which is applied to the screw connection 4. The opposite end of thenut engages a shoulder in the inner end of the intermediate head, and thereby assists in supporting the intermediate head, and the nozzle secured in the outer end thereof. At

"the same time, the nut-forms an annular chaintube. 5

A recess such as shown. at C is formed in the intermediate head. At one end thereof is a sec'- ondary burner nozzle 46 to which gas is delivered from the passage 20c through an orifice which is controlled by means of a neede valve 4l. The flame is projected against the wire by means of the burner nozzle 4B, and preheating thereof will thus take place before the wire enters the main wire guide and finally-the main burner nozzle where fusing and melting take place, and as considerable temperature may be imparted by means of the burner nozzle 46, it is obvious that the nnal work of bringing the wire up to melting temperature is materially reduced, thereby permitting a more rapid melting and atomization of metai wires having a high melting point.

The intermediate head is also employed for the purpose of heating the air employed for atomizing and confining the metal spray. That is, the waste heat from the ondary burner nozzle 46 will obviously rise and heat the central portion of the intermediate head,

' and in fact all of it, by conduction, and as nu about too rapid cooling of the melting metal as it is being 'atomized In actual operation, itwill be understood that the head A will be provided with a hand grip, not here' shown, and 'a valve mechanism which will not onyl control the flow of compressed air delivered to the gun, but also the ilow of combustible gases to the burner nozzle, and similarly, thata wire-feeding means of a similar character will be employed. In the present instance, when the wire is being fed through, it may or' may not be preheated, as desired, as Fit isoptional with the operator to use or'removethe intermediate head B. By extending the tube indicated at 0 to a point adjacent the wire'feeding rolls, any kinking or bending of the wire vprior to reaching the main wire guide is obviated. This main wire guide, and the preliminary guiding tube 6 will obviously be made of a hard steel or .similar metal, to resist wear as much as possible, while the plug I1 and the remaining portions of the nozzle will be Amade of a heat-resisting and heat-dissipating alloy. By providing a plurality of air jets at the forward end of the'nozzle, better. atomization and confining ofthe atomized metal is insured, with the result that a, dense, close-grained, deposit of small particles is obtained. The deposit is, fur--` thermore, uniform and can 4be formed of practically any metal desired, as use of the preheating -arrangement shown permits `the use of wire formed of metal having a high melting point. The nozzle structure shown permits the several parts to be quickly separated for removal, inter-4 change, cleaning, etc. The screw connection I formed between the inner end of the burner tube Y and the gun, insures perfect seating of the inner end of the burner tube. The 'screw' connection 23 formed between the nozzle I0 and the outer end of the burner tube permits perfect seating at that point, and by making` the wire guide 1 ci 'I flame produced by the sec- 25 af which the gas discharges.'

two separate pieces, to wit, the plug and the wire guide,l and by employing the spring I9, perfect been more or less specifically described and illus-v 15 trated, it is nevertheless to be understood that various changes may be resorted to within the scope of the appended claims, and similarly that the materials and finish ofthe several parts employed 4may be such as -the manufacturer may decide or varying conditions or uses demand.

- Having thus described my invention, what I claim and 'desire to secure by Letters Patent is as follows:

nl. In an apparatus of the character described,

a head member, having a cone-'shaped seat formed therein, an elongated wire guide, tapered at one end to fit and engage ,said seat; a burner nozzle surrounding and`encloslng thewire guide,

saidvnozzle having a taper at its inner end, which also engages the cone-shaped seat; a cone-shaped seat within the outer end of the nozzle; a taper- -ing plug longitudinally adjustable on the outer end of the wire guide, engaging and seating the cone-shaped seat of the nozzle, said nozzle being larger in diameter than the wire guide, to form an annular chamber between the wire guide and the nozzle; means for deliveringl a combustible 4gas to said chambers; and a plurality of grooves l formed in the outer' face of the plug, ithrough 2. In an apparatus of the character described, a head member, having a' cone-shaped seat formed therein, an elongated wire guide, tapered at one-end to lit and engage said seat;'a burneru nozzle surrounding and enclosing the wire guide, r said nozzle having a taper'at its inner end, which also engages the 'cone-shaped seat: a coneshaped seat'within the outerend ofthe nozzle;`

a tapering plug longitudinally adjustable on the l) outer end of the wire guide, engaging and seating the cone-shaped seat of the nozzle, saidgnozlzle being larger in diameter than the wire guide, to form an annular chamber between the wire guide and the nomle; means for delivering a u combustible gas to said chambem' a plurality of grooves formed in the outer face of the. plug,

.through which the gas discharges; a spring ini terposed between the wire guide andu thefplug. to forcethem against their respective seats; and

00 a screw connection between the burner nozzle and the head, to`secure the nojmleto the head,

and for simultaneously applying pressure to the spring. I.

3. In an apparatus of the character described,

UQ-thecombinationwiththemainburnernozzleand asoman l the guide for'directing a metal wire through the nozzle into a flame produced by the burner nozzle, of'a secondary burner nozzle disposed ahead of the wire guide, and adapted to direct a flame against he wire, to preheat the same before the wire ent rs the flame of the main burner nozzle.

4. In a apparatus of the characterdescribed, the combination with the main burner nozzle and 'the guide for directing a metal wire'through the nozzle into a flame produced by the burner nozzle, of a secondary burner nozzle disposed ahead of the wire guide, and adapted to direct a flame against the wire, to preheat the same before the Wire enters the flamefof the main 'burner nozzle; 'means for directing compressed air around and in front of the main burner nozzle to atomize the metal fused by the flame, and

Qand then lthrough the flame area of the main nozzle to fuse the metal, means for 'utilizing the heat. of theflame from the secondary nozzle to heat compressed air, and means for projecting the heated compressed air into the flame area of Y the main nozzle to atomize the fused metal.

` 6. In an apparatus of the character described r a main and a secondary burner nozzle, disposed in alignment with each other, said nozzles having a common central passage formed therein and extending. through them, means for supplying av lcombustible mixture to each nozzle to maintain a flame area in front of each nozzle, means for feeding a metal wire rst through the llame produced by the secondary nozzle, to preheat the wire, and then through the common passage into the flame area of the main nozzle, to fuse the metal, and means for atomiz'ing and projecting the fused metal.

7. In an apparatus of the character described a mainv and a secondary burner nozzle, disposed in alignment with each other, said nozzles havingl a common central passage formed therein and extending through them, means for supplying a" combustible mixture to each nozzle to maintain a flame area in front of each nozzle, means for feeding a metal wire first through the flame produced by the secondary nozzle, to preheat the wire, and then through the common passage into the flame area of the main nomle, to fuse the metal, -a third nozzle surrounding-V the main burner nozzle, means for directing'compressed air through the third nozzle into the flame area. ofthe main nozzle, to atomize the metal fused by said llame, and means for utilizing the heat of thesecondary nozzle ame to heat the .com-

pissed air before it enters the third nozzle. H. STEVENS.

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