US1990824A - Air nozzle for flat-spraying appliances - Google Patents

Description

Feb. 12, 1935. E. GusTAFssoN y 1,990,824

AIR NOZZLE FOR FLAT SPRAYING APPLIANCES Filed pill 16, 1934 Patented Feb.12,1935 i 1,990,824

UNITED STATES PATENT'OFFIC Al NOZZLE FOR FLAT-SPRAYING APPLIANCES Eric Gustafsson, Chicago, Ill., assignor to Binks Manufacturing Company, Chicago, Ill., a corporation of Delaware Application April 16, 1934, Serial No. 720,748 3 Claims. (Cl. 299-1401) My invention relates to the class of at-sprayis emitted is considerably increased, so as to ing appliances which are constructed for promeet the demand of automobile manufacturers jecting a composite stream -composed of coating for a speedier spraying of a coating of given material commingled with and partly atomized thickness over a given area, the supply of air 5 by air, and for impacting two opposed and forper minute for the air tube must be correspond- 5 wardly converging jets of air against thisA comingly increased, as also that of theair vfor the posite stream to complete the needed atomizaconverging air jets, so that the cost of the tion of the material and to atten the resulting needed compressed air rises undesirably. Morespray. over, even for spraying at relatively moderate l In the conventional spray guns, as commonly rate, the step of rst deforming the material 10 used for spray coating materials on automobile stream to an elliptical section having its longer bodies, furniture and the like, the material is axis in the same plane with the axes of the initially projected in a stream of cylindrical sec- (spray-nattening) converging air jets necessation and also is initially housed by a tube of rily requires the use of considerable air energy i air which merges with and partly atomizes the for this stream-section deformation. l5 material, this projected tube of air being ini- To reduce this consumption of compressed air, tially a hollow cylinder lhaving a uniform thickit has also been proposed that two auxiliary air ness throughout its circumference. jets be projected respectively contiguous to the When the material which is to be sprayed is two sides of the composite material stream of the nonhomogeneous class inv which nely against which the (spray-attening) converging 20 divided particles of heavy materials (such as a air jets are directed, several types of spray-apvitreous enamel) are intermingled with and carpliance heads for this purpose being disclosed ried by a liquid of considerably lower specific in the copending application #694,796 of Eric gravity (such as a pyroxylin lacquer) and which Gustafsson, led October 23, 1933 and assigned liquid oiers considerable resistance to a change to the same assignee as my present application. 25 in the cross-section of the projected stream of However, with the just recited disposition of the material, the flattening of the spray to the usutwo auxiliary air jets, these auxiliary jets really desired section of a highly elongated ellipse spectively commingle with the two converging or rectangle requires the` air of the two convergair jets, so as to concentrate the effect of the ing air jets to be projected at such pressure that atomization near the common plane of all of the 30 this spray-attening air will nick an objectionsaid jets. Consequently, when the rate of air ably large part of the heavy constituent of the supply for the auxiliary air jets is increased to material out of the carrier liquid, thereby causcorrespond to the rate at 'which the material ing such an amount of off spray as to require is projected for quite rapid spraying, a considerthe coating. l material is icked out of the liquid carrier to This diiiiculty can readily be overcome (after form an off spray, and the total 'air consumpthe manner disclosed in United States Patent tion (in proportion to the material consumption) #1,897,173, issued February 14, 1933 on the joint also rises undesirably.

40 application of Robert Long and myself) by My present invention aims to overcome the 40 thickening the wall of the projected tube of air heretofore recited objections, as particularly enalong the two sides of the material stream which countered when spraying material at a higher are at right angles to the common plane of the rate per minute than has previously been cusaxes of the two converging air jets, so that the tomary, by providing an arrangement ofair considerable hand labor for its elimination in able portion of the heavier ingredient of the 35 increased volume of air supplied along the said ports which will decidedly reduce the consump- 45 t two sides of the material stream will first flatten tion of compressed air in comparison to the volthe aforesaid composite stream in a direction ume of the sprayed material, 'while also preat right angels to that in which` the converging venting the production of an undesirable Iamount air jets thereafter atten the-spray. In practice, of oi spray and aiording such a distribution the air nozzle of the just mentioned patent has of the particles of the sprayed material that 50 proven satisfactory only when the material is to these particles will readily ow into one another be sprayed at a fairly moderate rate per minute in the resulting coating. ,I in proportion to the diameter of the initially Generally speaking, I accomplish these objects emitted stream of material. by combining the operating principles of the air Y However, when the rate at which the material nozzles both the said Long and Gustafsson Pat- H ent #1,897,173 and .of my said application #694,796 by so reproportioning the emission of the air streams which commingle with the projected material stream before the impact of the converging (spray-flattening) air jets on the resulting composite stream, so as` to increase the diameter of this streamI both along the common plane of the axis of the converging air jets and along a plane axial of the said composite stream and at right angles to the aforesaid stream.

More particularly, I accomplish my above recited objects by constructing a spray-appliance air nozzle in which the provisions, auxiliary to the conventional projecting of a cylindrical tube of air around the initially projected material stream, for projecting air into merging relation with this material stream are so arranged that the auxiliary air will form two longitudinal air ribs projecting from the material stream andV against which the converging air jets respectively impact; and also will form two other longitudinal air ribs projecting from the material stream with the `axes of the last named air ribs disposed in a plane at right angles to the common plane of the axes of the converging air jets', and with the last named air ribs of greater spread (circumferentially of the material stream) and less thickness radially of that stream than the rst named airribs.

Furthermore, my invention is based on my discovering, as the result of a long series of experiments and observations, that by the here disclosed projecting of auxiliary air along four sides of the projected material stream, and the here disclosed proportioning and directing of the auxiliary air, I enable the various portions of this auxiliary air to cooperate in such a manner that the total amount of compressed air required for producing a spray of given atomization from a material stream projected at a given pressure is much less than the amount of compressed air which I have found to be required for the same purposes with older types of spray appliances.

In the accompanying drawing,

Fig. l is a central and Vertical sectionthrough the forward parts of a spray gun constructed for operating according to my invention.

Fig. 2 is a front elevation of the same.

Fig. 3 is an enlargement of a part of Fig. 2.

Fig. 4 is a perspective view showing the streams projected by the spray head of Fig. 1, when no spray-flattening air is emitted from the side air ports. K

Fig. 5is a similar perspective view, taken when air is also issuing from the vside air ports. Fig. 6 is an enlarged approximate cross-section of the composite stream shown in Fig. 4, taken along the line 6-6 of Fig. 4.

Fig. 7 is an enlarged front elevation of the central portion of analternativeform of my air nozzle, namely one in which two separate air ports are substitutedifor the enlargements of the bore of the central air port shown in Fig. 3.

Fig. 8 is a fragmentary sectional view taken on line 8-8 of Fig. 3.

vIllustrative of my invention, the drawing shows thisas applied to a spray appliance of theY Svend Bramsen Patent #1,910,673 of May 23, 1933 on a Spray gun.

In` the portions of a thus modified spray gun shown in Fig. 1, the gun body (or barrel) 1 has two longitudinal fluid passages, one being a ma,-

terial passage 2 into the forward end of which the rearend of a material nozzle 3 is threaded, and the other being a compressed-air supply passage 4. The forward end of the gun body 1 is formed to afford an air chamber into which the air passage 4 opens, and from which chamber air can issue (through an annular port 5 in the forward wall of this air chamber) so as to flow around and alongside the `material nozzle 3.

Abutting against the front end of the gun body and freely surrounding a part of the material nozzle is a partitioning tube 6 which spaces the air nozzle of the appliance forwardly from the gun body and which has an annular baille web 7 extending radially outwardly from it. As here shown, the air nozzle N is of a conventional type, shaped generally as a rearwardly open cup which has its rearward portion sleeved on the forward part of the tube 6, and lwhich has forwardly projecting horns H at diametrically opposite sides of a central flat-faced frontal portion 9. A retaining ring R supports the air nozzle from the gun body and also clamps the verging side ports 12 from -which the sprayflattening side air jets S (Fig. 5) are emitted,

the supply of air to the two side ports beingsubstantially equalized by the baffle web 7 which has its periphery spaced from the bore of retaining ring R by a minor fraction of the radial width of the said web so as to compel some of the air to flow around the partitioning tube 6 after the air has been admitted behind this baffle through the valve-controlled port 8.

Mfr also flows forwardlyfrom the air chamber C through the body-front port 5, the space between the partitioning tube 6 and the materialnozzle 3, and through longitudinal ports 13 in the air nozzle (as indicated by the lower set of arrows in Fig. 1) into the forward central portion of the cup-shaped part of the air nozzle,

so as to issue through the commonly provided central frontal air port around the exteriorly cylindrical tip 15 of the material nozzle. /In the air nozzle of the said Bramsen patent, which is owned by the assignee of my present application, this central air port was circular and of cylindrical bore, as shown at 14 in Fig. ,7, and

was the only forwardly opening port in the.

central portion of the air nozzle.

To adapt theheretofore described prior construction to non-homogeneous materials now widely used for coatings and to reduce the amount of compressed air needed in proportion to the sprayed material, I augment the previously employed annular central air port by either.

of the two provisions respectively shown in Figs. 3 and 7, namely by arrangements for projecting an increased amount of air longitudinally alongside and in merging relation to the material at four sides of this stream, with this additional air suitably proportioned to the diameter of the side air ports 12.

In the embodiment of Figs. 2 4and 3, ,the central air port 14 has two diametrically opposite bore enlargements 15, each having substantially semi-cylindrical interior surface the axis of which is in a plane T axial of the enlarged parts of the port 14 (and `hence coaxial with the tip 16 of the material nozzle) and at right angles to the common plane P of the axes J (Fig. 1) of the side air ports 12. Each of thesey bore enlargements also preferably has its axis sloping rearwardly away from the axis A of the liquid nozzle, as in Fig. 8, so that each bore enlargement tapers forwardly at an angle of not exceeding approximately 10 degrees.

Each such bore enlargement desirably extends for approximately one quarter of the circumference of the central air port, and has its central and maximum width (radially of the said port) a minor fraction of its said circumferential spread, the general proportioning of the central air port being desirably such that the area of each of these bore enlargements is not greater than the area of one of the side air ports 12.

By thus using a taper angle of a maximum only about half as great as that shown for the allied, but differently positioned, bore enlargements in the air nozzle of the -Long and Gus- -tafsson Patent #1,897,173, I cause each bore enlargementto function partly (but less intensely) after the manner of the just named patent in tending to change the cross-section of the material stream, and partly (after the manner of the separately formed cylindrical ports of my own copending application #694,- 796) to form a longitudinal air rib along the material stream. l i

To co-operate with these enlargements of the central bore of the air nozzle, I also provide two auxiliary and preferablyI cylindrical air ports 20 of cylindrical bore, which ports have their axes parallel to and equally spaced from the general axis of the air nozzle and at a sufciently short spacingso that the air emitted from the said auxiliary ports 20 will merge with the air projected through the previously described central air port and form longitudinal air ribs at opposite sides of the material stream. Each of these auxiliary air ports 20 is of smaller area than one of the said bore enlargements 15 of the central air port, and has its axis in a common plane P (Fig. 3) with the axes J (Fig.

1) of the side air ports 12, namely a plane diametric of the material discharge port 16 and of the central air port of the air nozzle.

When my thus constructed spray appliance is in use, with a stream of material issuing from the discharge port 16 of the material nozzle, and with air issuing around the tip of that nozzle, through the central air port, but with the valve 10 closed so that no air is issuing from the side ports 12, the observed operation is substantially as pictured in Fig. 4, namely as follows:

The contour of the four-lobed tubular stream of air issuing from the central air port corresponds initially to that shown for this port in Fig. 3, and if the auxiliary ports 20 Were not present, the increased amount of air issuing through the enlargements 15 of the central air port would act (after the manner disclosed in the Long and Gustafsson Patent #1,897,173) to change the cross-section of the material stream to an elliptical section having its longer axis in the common plane P with axes of the side ports 12.

However, the two jets of air B which issue from the auxiliary air ports 20 quickly join the air issuing from the central air port, as shown in Fig. 4, and when the several air ports are pro-y portioned as previously described, vthese auxiliary air jets prevent a changing of the general vmaterial makes the resulting composite stream of approximately the cross-section (in the transverse plane along the line 6-6 of Fig. 4) which is shown on an enlarged scale in Fig. 6, namely with two diametrically opposite lobes Ca of relatively small thickness (radially of the composite stream) both centered along the plane T of Fig. 3, and with relatively narrower lobes Cb of considerably greater radial thickness diametrically opposite each other and each centered along the plane P of the same gure.

When the valve 10 is then opened so that forwardly converging air jets S issue also from the side air ports l2 in the horns of the air nozzle, each of these side air jets impinges against one of the` ribs formed on the composite material stream'by the lobes Cb of Fig. 6, so as to prevent a splitting or undue indenting of Ythis stream, While the other two ribs (corresponding to the lobes Ca) partly compensate for this by already widening the composite stream along the -plane T 4(Fig. 3) in which the spray isto be flattened. Consequently, when the valve 10 is only partially opened, so as to flatten the spray to a still decidedly elliptical section, the projected fluid portions adjacent to the forward end of the spray-gun appear approximately as shown in Fig. 5.

By thus distributing the air, which commingles with the material stream to a considerable extent before the side air jets impinge on the resulting composite fluid stream, I have found that I can secure a uniformly fine atomizing of -the material with any desired extent of the flattening of the spray (which is controlled by adjusting the valve 10) with a considerably smaller total consumption of .compressed air than that heretofore needed for the same purpose. For example, with one of the coating materials nowv commonly usedA on automobiles, namely the Du Pont De Luxe lacquer, I have reduced the air consumption (for spraying a given quantity of material) from 35 cubic feet per minute to 25.

I have also found that my new air nozzle will permit the rate of material spraying to be increased without increasing the air consumption in the same ratio, so that my present invention .effects a large saving of air when the spraying is done at high speeds so as to increase the surface area which can be sprayed per hour by a single spray gun.

In addition, I have found that a spray gun constructed as here disclosed will effect such a decided saving of air, and permit such a reduction of the spraying time, with widely varying materials, including those having heavy pigments (such as vitreous enamels), socalled synthetic lacquers and enamels, and asphalt emulsions.

Owing to my supplying an increased quantity of air along four sides of the projected stream of materials, I have also found that such materials are atomized to a more uniformextent than by the spray appliances heretofore employed for the same purpose, consequently the resulting coating is so much more uniform as to require less sanding (rubbing down with -sand-paper) before another coating is applied,

and in many cases a reduced number of layers of coating material are adequate for securing a really smooth surface.

Consequently, the fspeedy `of air and improves the uniformity of the coating when the material is projected under relatively low pressure, as for example from socalled Siphon-cup spray appliances, where the material pressure may be only about 5 pounds. However, while I have heretofore described the use of lobe-like enlargements of the central port of the airnozzle for affording the addi-v tional air along the plane T of Fig. 6, I do not wish to be limited in this respect, as I have obtained approximately the same advantages by employing two supplemental air ports in substitution for the said bore enlargements. Thus, Fig. `'I shows the central frontal portion of an air nozzle with the central airport 14 circular, and with two supplemental circular air ports 21. having theiraxes equally spaced from the axis. of 4this central port and in the plane T (diametric of the said port) at right angles to the diametric plane P in which the axes J of the converging side air jets of this nozzle extend.

In this alternative form of my air nozzle, I have found that the supplemental air ports 21 are preferably of cylindrical bore, of a diameter approximately one-third greater than that of the auxiliary ports 20 (which would bein the same proportion to the size of the side air ports 12 as in Figs. 1 to 3), and with the axis of each supplemental air port spaced by approximately its own diameter from the-circular central air port. With this type, it will be noted that the area of each supplemental air port, port 21 is intermediate that of. each auxiliary air port 20 and of the area of one of the counterpart side air ports 12. w It will also be noted that diameter of each of the larger two air ports adjacent to the central air port is considerably smaller than the diameter of the material discharge port, this difference in size being required in order that produce four separate projecting ribs (shown at 'A and B in Fig. 4) instead of merging into one another.

Moreover, while I have described my here presented air nozzle as used on a particular type of spray gun, it is to be understood that this isY merely illustrative of its use, and that many changes might be made without departing either from the spirit of my invention or from the appended claims.

I claim as my invention:

1. In` an appliance for producing a flattened Spray, a material nozzle having a discharge tip through which material lis projected forwardly; and an air nozzle having two side ports, respectively at opposite sides of the axis of the said tip, for projecting jets of air along forwardly converging jet axes lying in a common plane with the saidtip axes; the air nozzle alsobeing provided with a group of ports for projecting air generally parallel to the tip axes and around and. in merging relation to the initially pro` jected stream of material; the said ports being so proportioned and disposed that air projected through them will form two pairs of diametrically opposite ribs on f the composite stream formed by the intermingling of air with the projected stream, with the ribs of one pair respectively facing the two side air ports, and with each of the other ribs equally spaced from the f aforesaid two ribs.

nsv

2. A spray appliance as per claim 1, in which the ports of the said group are so proportioned and arranged that the ribs facing the two side ports are of greater thickness, radially of the composite stream, than the other two ribs.

3. A spray appliance as per claim 1, in which the ports comprising the said group have their mouth ends substantially in a common plane at right angles to the axis of the discharge tip of the material nozzle.

4. In an appliance for producing a flattened spray, a material projecting nozzle having a forwardly open tip; an air nozzle presenting two side ports, respectively at opposite sides of the axis of the said tip, for projecting jets of air along two forwardly convergingvjet axes lying in a common plane with the said axis; the air nozzle having in itsv central portion a group of ports for projecting air generally coparallel to the said tip axis around and in merging relation to the initially .projected stream of material but with a smaller proportion of the air projected along the two sides of the said stream which face the side air ports' than along the other two lsides of the stream which are in a second plane cal contour; and an air nozzle having a. central i',

air port coaxial-with and freely housing the said tip, and having two counterpart side air ports for projecting air from opposite sides ofthe axis of the said tip along two forwardly converging jet axesv lying in a plane diametric of the said axis; the central air port having abore of substantially elliptical section with the minor axis of the ellipse in the said plane; the airl nozzle also having two counterpart auxiliary ports coparallel with the central air port and respectively at opposite sides of and equally spaced from the lsaid central air port, the axes of the said auxiliary air ports lying in the said .plane and the area of each auxiliary air port being a minor fraction of the area of one of the side airports. v

6. A spray appliance as per-claim 5, in which the substantially elliptical section of the bore of the central air port is such that the increase in area of each of the two 'halves of that `port at opposite sides of the vsaid plane, at the mouth end ofthe port, is intermediate between the area of one of. the side ports and that of one of the auxiliary air ports.

7. In a spray appliance in which generally liquid material is projected through the tip of a material nozzle, an air nozzle having a central air port coaxial with and freely surrounding the said tip of the Asaid material nozzle and having two side air ports for projecting converging jets of air along two axes disposed in a plane diametric of the said nozzle tip and intersecting on the axis of the nozzle tip; the air nozzle also having port provisions for projecting air forwardly contiguous to the stream of material projected by the material nozzle, the said port provisions being formed so that vthe air afforded by them will initially entirely surround the .projected stream of material and will transform the said projected stream, before the impact of the said jets against the stream, to a partially aerated ,stream having a four-lobed cross-section having two opposite lobes extending symmetriv cally across the said plane and the other two lobes of less radial depth extending across a second plane diametric of the said nozzle tip and at right-angles to the aforesaid plane.

8. In a spray appliance in which generally liquid material is projected through the tip of a material nozzle, an air nozzle having a central air port coaxial with and freely surrounding the said tip of the said material nozzle and having two counterpart side air ports` for projecting converging jets of air toward a common point on the axis of the projected stream of material; the bore of the central air port being circular except for two diametrically opposite and counterpart bore enlargements each of a spread approximating one quarter of the circumference of the said bore and of a maximum depth inH a plane diametric of the said axes and at right angles to a common plane including the axes of one of the auxiliary air ports, each of thesaid auxiliary ports being of smallercross-sectional area than one of the said recesses; the said auxiliary air ports being at opposite sides of the central air port and having their axes in the said common,.plane, and the area -of each bore enlargement being less than that the sideair ports.

ERIC GUSTAFSSON.

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