US2436335A - Spray device for projecting molten particles - Google Patents

Description

Feb. 17, 1948. 1.. M. SIMONSEN SPRAY DEVICE FOR PROJECTING MOLTEN PARTICLES Filed Dec. 17, 1943 2 Sheets-Sheet 1 Y NI Euros; L eo/Z 5/70/756/7. BY

\KMW mwwwwv N AN mm MN HTTORNEY Feb. 17, 1948. L. M. SIMONSEN 2,436,335

r SPRAY DEVICE FOR PROJECTING 'MOLTEN PARTICLES Fil'ed D80. 17, 1943 2 Sheets-Sheet 2 .INVENTOR. Lea M- 5/m0/7sen fla 19% ATTORNEY Patented Feb. 17, 1948 UNITED STATES PATENT. OFFICE SPRAY DEVICE FOR PIOJECTING MOLTEN PARTICLE Lee M. Simona. Eugene, Oreg. Application December 1'8, 1943, Serial No. 514.63%}

usual melting zone of spray guns or devices of this character is critical due to the fact that it must provide a high temperature for'sumcient time interval to melt the material but not so long that the material will be burned by the intense heat generated.

Furthermore, in the spraying of. metallic materials it is desirable to do so in what is known as a reducing atmosphere in order to avoid ex. eessive oxidation of the molten particles, while on the other hand, in the spraying of certain nonmetallic materials, it is advantageous to do 'so in an oxidizing atmosphere. For example, in the spraying of nickel or chromium powders, a high initial melting temperature is necessary and a reducing atmosphere is desirable. -In the spraying of aluminum, zinc, tin, lead. or solder powders. a lower initial temperature is necessary and a reducing atmosphere is advantageous. In the spraying of glass or ceramic glazes, particularly those known as sulphide glazes, a fairly high initial temperature is necessary and an oxidizing atmosphere is desirable, whereas in the spraying of materials known as plastics, in powdered form, a low temperature only is required and either an oxidizing, neutral, or reducing atmosphere is used depending upon the composition of the plastic utilized.

In the use of conventional devices of this character, when a high initial melting temperature is required-to melt the powdered material within a given time, there is the danger of overheating the surface upon which the molten metal impinges or adheres. This condition is usually overcome by altering the distance between the gun nozzle and the base upon which said molten metal is to impinge, and by increasing the air pressure behind the molten particles, in which event, there is increased oxidation of the molten material during its trajectory through the flame from the gun nozzle to the base surface. Furthermore, during the spraying of powdered glass or glazing material the preheating of the base surface to a higher 5 (Jlaimo. (cl. 01:42.2)

temperature than that required to initially melt the glass or glaze, is advantageous to aid in ore ating a satisfactory bond between the glaze or glass and, the base surface and to create a means a of creating a uniformly annealed, vitreous coating.

It is an object-of the present invention to provide a spray gun having a wide range of adaptabllity and flexibility to suit varying conditions and materials being applied.

l0 It is a further object of the present invention to provide a spray gun in which, when a higher initial melting temperature is required to melt the powdered material within a given time, there is not danger of overheating the surface upon which ll the molten material impinges.

It is a' further object of the invention to provide a spray apparatus with which, during the spraying of powdered glass or glazing materials, preheating of the base surface to a higher temper- I. ature and over a larger area than that required to initially melt the glass or glaze, may be obtained.

It is a further object of the invention to provide a spray apparatus in which the powdered ll metal or non-metal or mixture thereof, is introduced into the flame at a point distant from the gun in such a manner that its melting may take place at a proper time with respect to the base surface.-

Other objects and advantages of the present invention will appear from the following descrip. tion in which the preferred embodiment is set forth in conjunction with the accompanying drawings. ll Referring to the drawings:

Fig. 1 is a longitudinal sectional view of a spray apparatus incorporating my invention.

Fig. 2 is a. cross-sectional detail taken along the line 22 of Fig. 1.

60, Fig. 3 is a cross-sectional detail taken along {*the line 3-3 of Fi 1.

Fig. 4 is a diagrammatic representation of the manner in which the powdered material is fed into the flame and the manner in which it strikes the base surface, together with an elevatlonal 60 of the manner in which it strikes the base surface, together with an elevational representation of the orifice used.

Fig. 6 is a diagrammatic representation of the manner in which the powdered material may be I feed into the flame together with a representation it is not absolutely essential inasmuch as suitable gasket means may be provided as will hereafter be explained. Body "I! is provided with a mixing chamber II which divides body I! into two concentric shell or wall portions It and 85. Inner shell portion." .isgeneraliy deeper than outer shell I and extends-forwardly along tube ill as shown. Chamber. is closed by an annular rin shaped plate It which is adapted to fit around shell portion ll andto abut against the forward face of shell portion. Plate It is provided with orifices H which allc'm passage of gas from chamber l3.

Tubular member Ilia mounted on body l2 as by means of threads on its inner surface which. are adapted to cooperate with threads IS on shell l5. It will be seen that when tube II is mountedupon member II, it will contact plate It and urge it snugly against the forward race of shell it. A plurality of orifices; 2! are provided in member l8 and are arranged preferably in banks oi four,

although that is not an essential part ofthis invention. r

Tubular member 21, which is of greater diamel 4 Thus I have provided annular fiange 24 on the rear end of member l2. A suitably flanged ring 8' engages flange N and is secured by means of bolts 31 to a nut 18. This nut together withlock nut ll engages threads ii on member ID to retain tube II in an adjusted position.

As has heretofore been pointed out the slidable connection between members It and I2 should be as gas-tight as possible. In the event machine operations do not permit a thoroughly gas-tight connection to be maintained, suitable ter than tubular member II, is mounted uponouter shell ll andisconcentric with respect to tubular members II and II. Cooperating threads on members N and I: rovide means whereby.

they may be united or separated at will.

I have provided acircular plate 22 the outside diameter of whichis substantially equal to the inside diameter of tube 2i. Plate 22 is provided with two concentric rows of orifices 22 and 24 respectively, and on its rear face. with a circular groove 25 concentric with and lying between said concentric rowsof orifices. Circular groove 25 is gasket or bushings may be utilized in any suitable manner.

Operation of my device may be briefly described as follows: Tube II is connected to a suitable source of air-under pressure. Suitable means is provided for feeding the material to be applied, in powdered or granular form, into the air stream, whereby a constant flowof air with divided solids homogeneously distributed therein is maintained through tube ll.

Chamber II is likewise connected by means of orifices 82, and 33 to .a suitable source of air or oxygen or a mixture of air or oxygen, and any natural or artificial fuel gas desired. These gases,

coming in at an angle-of 90 to each other are thoroughly mixed, and the curved rear surface of chamber I3 assists materially in the mixing operation and also in projecting the gaseous mixture forward. The gaseous mixture passes through orifices II in plate It into the chamber between members It and H.

mixture willlpass ,through orifices 20 into the A portion of this orifices 24 because the latter are smaller and be-' cause the pressure within the chamber defined by tubes 2! and fl is slightly greater than the pressure within the chamber defined by tubes It. and II. The material-laden air is discharged adapted to accommodate 'and locate the adjacent I end of the tubular member ll. Plate 22 is also provided with a centrally located threaded orifice 26.

A nozzle or tip 21 is likewise threaded and is adapted to cooperate with the threads in centrally disposed orifice 20 whereby the nozzle may be removed or replaced at will. Tip 21 is bored to-snugly fit about the adjacent end of tube In. without however interfering with adjustment of the latter. g

Circular plate 22 is maintained in its position by means of interiorannular fiange 2! on member 2|. when member 2! is mounted upon member H, n e 2| isurged against the outer face of member 2 and plate 22 is thereby gripped between fiange 2| on member II and the .forward end of member II, which lies in circular groove from tube ll and nozzle :1 into this general flame formed by the intermerging Jets. The pattern assumed by the finely divided material being pro- Jected will. depend upon certain factors, including, the distance between the discharge and of tube II and the discharge endof nozzle 21. When these parts are relatively far apart as shown in 4,.the pattern assumed by the finely divided material is that of a cone somewhat as illutsrated and the finely divided material is dispersed accordingly. when the two discharge orifices are positioned -.relatively close together as shown in P18. 5, the pattern assumedby the discharged material is more limited and the pattern is more compact as the finely-divided material is not so widely dispersed. 1 t

' The reason for the above is that for the retracted position of Figure 4 the spread of the discharging jet is determined largely by the convergent orifice in nozzle 21, whereas for the position of Figure 5. the discharging Jet assumes some of the characteristics-of a jet discharging from an extended cylindrical orifice. It is well known that an air or gas jet issuing-from the end of a converging orifice tends to spread over a wider area than a jet issuing from an extended cylindrical orifice (assuming like efiective .fiow areas and pressures) due to the lesser efficiency of the former, to the attendant turbulence of the issuingair stream, and to the tendency of the stream to b slightly contracted in a region near the diacharge end of the nozzle, beyond which region the stream tends to expand.

By employing natural or artificial gases such as propane, butane, acetylene, etc., in combination with air or oxygen, a wide variety of flame temperature is possible. Also by varying the volume of either the natural or artificial gas in relation to the volume of air 01' oxygen employed an oxidizing or reducing flame is obtained thus fulfilling one of the objects previously mentioned herein. By increasing the pressure of both gas and air and assuming the same volume ratio, a longer flame is obtained between the gun nozzle and the base plate on which the material is to be deposited. By providing this type of adjustment, a range of from high to low temperature near the nozzle, a sustained range of from high to low temperature throughout the flame trajectory, and a variable flame length, each part of which can be an oxidizing, neutral, or reducing atmosphere as desired, are all obtained.

As previously pointed out, by altering the'longitudinal relationship between the discharge ends of tube i0 and nozzle 21, it is possible to obtain a variable length of material cone in either an oxidizing or reducing temperature created by the flame. It should also be noted that by varying the quantity of powdered material to that of the entralning air, a further adjustment is possible, and in some instances it is necessary, particularly in consideration of the latent heat of fusion of various metals and their specific gravity. As

an example, a powdered metal with a high latent heat of fusion and a high specific gravity will require a low feed rate and a high air pressure in order to permit the suspension of the particles in the air.

with oxygen in order to maintain a melting temperature commensurate with the latent heatmelting time function, whereas a material hav- 6. 'stantiaily rectangular as shown in Fig. 6. the

pattern of the entrained material upon the base to which it is being applied will be substantially similar thereto. Generally speaking, therefore,

it may be said that the pattern of the material upon the base will conform generally to the type of orifice in the nozzle 21. Furthermore, it may be pointed out that the size of the pattern upon the base will be a function of the distance be- This condition automatically calls for a fuel of high calorific value in combination ing a low latent heat of fusionand low specific gravity may be readily floated with low air pressure and readily melted in a flame of natural gas and air.

Further control of the flame is obtained by the type of tip 29 which is employed. The tip may be either a straight tube acting merely as a continuation of tube 2|, which is in reality the outer shell of the gun body, or it maybe flared inwardly or outwardly at varying degrees depending upon the shape of the flame desired. For example, a, tip flared inwardly as shown in Fig. 1 will yield a concentrated flame body which is necessary particularly in the spraying of high melting point powders where a highly localized preheating of the base surface upon which the powder is to be applied is advisable and where an excessively large preheated area is not necessary. On the other hand, in the event one is spraying glass and glazing powders, in which case a lower initial melting temperature is required and an enlarged preheated area is essential (particularly in the application of spraying glassin connection with repair work), an outwardly flaring tip would be more satisfactory.

It has already been pointed out that the relationship between the exhaust orifices of tube ill and nozzle 21 control the path of the entrained material. For example, a nozzle flaring inwardly as shown, the orifice of which is circular, will yield a circular material feed into the flame the diameter and length of which will be determined by the position of the two orifices. On the other hand. in the event the orifice is square, or subtween the exhaust nozzle of tube In and nozzle 21, that is, the greater the distance between these two orifices, the larger the pattern, assuming the distance from the base remains the same.

It has previously been pointed out that I provide a plurality of concentric rows or orifices 23 and 24. The purpose of the inner row of orifices is to produce flame as close to nozzle 21 as is feasible. In this manner the entrained material is placed directly into the flame and a nearly solid shaft of combustible gases is obtained. Lack of this particular inner row of orifices is noticeable in the case where the outer flame ring alone is used in combination with a short material feed cone, in which a satisfactory preheated base surface is obtained coupled with a short material cone of insufficient length to properly apply the material to the base plate unless the gun is held excessively close to the base plate. It will be recalled that it is desirable to inject the entrained materal into the flame as early as possible, provided, however, that the flame can be controlled. I have provided ample means of control, for example, the two circular rows or orifices 23 and 2|, theinwardly or outwardl flaring tip 29, a particular form of nozzle 21, and the method of increasing or decreasing gas pressure in chamber I3.

I claim:

1. In a device for spraying molten particles of material upon a surface to provide a coating thereon, a nozzle from which said material is discharged,.a tube communicating with said nozzle and adapted to convey a stream of said material entrained in air, means for creating a zone of flame concentric with said nozzle and extending from said device to said surface, and means for controlling the trajectory of said particles through said zone of flame comprising means for controlling the distance between the discharge end of said nozzle and the adjacent discharge end of said tube.

2. In a device for projecting particles of material upon a surface to provide a coating thereon, a tube adapted to receive a stream of particles entrained in air, a nozzle communicating with said tube, means for creating a zone of flame surrounding the nozzle and extending between said nozzle and said surface, a tip generally surrounding the discharge end of the nozzle and serving to determine the spread of the flame pat-' centric chambers, orifices serving to connect said chambers, means for supplying a combustible mixture of fuel gas to the outer one of said chambers, and a member surrounding said nozzle and having separate concentric groups of orifices communicating with said chambers, flame jets from said last named orifices serving to form a from the nozzle.

4. In a device for discharging molten particles oi material upon a surface to provide a coating thereon, a nozzle through which said particles are discharged, means for creating a zone 01' flame concentric with said nozzle and extending from said device to said surface. whereby said particles will pass through said zone of flame and be melted thereby, and means for controlling the trajectory of said particles between said nozzle and said surface comprising a tube having a discharge orifice through which said particles pass, the discharge end of said tube being mounted in said'nozzle and longitudinally movable with respect thereto, and means for longitudinally adjusting said tube with respect to said nozzle.

5. In a device for spraying molten particles of material upon a surface to provide a coating thereon, a, nozzle through. which said material is discharged, means for creating a zone oi flame concentric with said nozzle whereby said particles will pass through said zone of time and be melted thereby, a tube communicating with said nozzle and longitudinally movable with respect 8 thereto, said tube adapted to carry particles entrained in gas. means for controlling the distance between the discharge end of said nozzle and the discharge end of said tube to adjust the pattern of said particles upon said surface for a given location of the device relative to said surface.

LEO M. SIMONSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,108,998 Schori Feb. 22, 1938 788,764 Fitton May 2, 1905 2,125,764 Benoit Aug. 2, 1938 2,137,442 Gallon Nov. 22, 1938 1,930,373 Stubenrauch Oct. 10, 1933 988,271 Lee Mar. 28, 1911 2,259,215 Scheuser Oct. 14,1941

FOREIGN PATENTS Number Country Date 255,932 Great Britain July 28, 1926

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