US2895685A - Spray nozzle - Google Patents

Description

July 21, 1959 D. J. PEEPS SPRAY NOZZLE Filed Feb.V 29, 1956 INVENTOR. v 00A/ALD J. PEEPs ATIQRNEY niteci States Patent SPRAY NOZZLE Donald J. Peeps, Rossford, hio, assignor to The De Vilhiss Company, Toledo, Ohio, a corporation of Ohio Application February 29, 1956, Serial No. 568,565

3 Claims. (Cl.A 239-400) This invention relates to a spray nozzle utilizing cornpressed air for atomizing a liquid, generally a coating material, and particularly to such a spray nozzle which mixes into the liquid during the discharge and atomization thereof a considerably lesser quantity of an additive agent. This type of spray nozzle is used, for example, in dispersing a catalytic curing agent through a resin or plastic surface coating material.

The spray nozzle of this invention is adapted for employment upon a spray gun of theA various designs disclosed in my application Serial No. 419,432 filed March 29, 1954 now U.S. Patent No'. 2,786,716. In these guns the additive agent is introduced into either a portion or all of. the atomizing air before the air is emitted into atomizing relation with the coating material.

While standard spray nozzles such as shown in my aboveidentied application, have proved generally satisfactory for thoroughly intermixing and applying a resin coating and a curing agent, such as an epoxy resin and anv amine, more viscous resins, such as polyisocyanates, have been developed which are not readily handled by standard spray nozzles. Also there have arisen requirements for faster coating production which such nozzles do not satisfy. In addition to this capacity limitation of the standard nozzles they are also decient in thoroughly mixing the catalyst or other additive agent into the more viscous resins or into resins discharged at a high rate.

The principal object of this invention is the provision of a spray nozzle which eiiiciently mixes an additive agent into viscous resins or other materials and will apply such materials in well atomized condition quickly in substantial quantity.

This object is primarily attained by dividing the stream of atomized air into a plurality of parts to form an annular jet around the material discharges orce and a series of round jets encircling the annular jet. Contributing to a lesser extent to the achievement of this object is the provision of means for circumferentially distributing the air into multiple channels internally of the nozzle and at the same time imparting to it a whirling motion. The attainment of the object is also aided by the adoption of a conventional enlarged form of coating material discharge tip.

Other objects and advantages of the invention will be apparent upon reading the following description and referring to the drawings in which:

Figure 1 is a side elevation of a spray gun with a spray nozzle embodying my invention;

Figure 2 is a vertical longitudinal section of the spray nozzle shown in Figure 1;

Figure 3 is a schematic presentation, mostly in section comparable to that of Figure 2, of the spray nozzle and passages for the air, coating material and the catalyzing agent leading to the nozzle;

Figure 4 is an enlarged front elevation of the insert located within the nozzle;

Figure 5 is an enlarged front elevation of the air cap of the spray nozzle; and

fifa

Figure 6 is a side elevation with portions broken away of a special air cap with a tubular extension.

Referring to the drawings in more detail the spray gunv 1 of Figure 1 has a conventional handle 2 and operating trigger 3. The supply of atomizing air enters the spray gun through the air inlet connection 4- and the flow of air is controlled by air valve 5. Coating material reaches the spray gun through connection 6 and its discharge is governed by valve 7. Inlet 8 for the additive agent is alongside connection- 6 and the ow of additive agent is controlled by Vailve 9. The air cap 11 forming a part of the nozzle is held on the spray gun by retaining net. 12.

Amore complete description of the spray gun structure is not considered necessary here as this invention is directed to the nozzle only andmy aforesaid application Serial` No. 419,432 contains detailed drawings and a description of this gun design.

As illustrated in Figures 2 and 3 a coating material passageway 14, extending from inlet connection 6, leads to the material discharge tip 15 in the rear'end of which the valve 7 seats.

The air passage arrangement is designed for more conventional'types of spray nozzles and it is somewhat more involved than necessary to meet the requirements of the nozzle of this invention.

The main air passage carrying air from valve 5 is portrayed as 17 and continues as 18 beyond lateral branches 179 and 20. The passage 18 terminates in an-` nular chamber 2l from which the air travels forwardly through the circular series of ports 22 in the air distributing ring 23. Thisair` then passes flange 24 of the tip 15 and through ports 26 into chamber 27 where it is joined by the air diverted down branches 19 andl 20.

Both of these branches lead into the annular channel 29, but before branch 20 reaches the channel it is intercepted by the additive agent injection passage 28, through which the small quantity of additive agent is-continuously introduced into this portion of the atomizing air stream.

The air from branch 20 carrying the additive agent joins air from branch 19 in the channel 29 and particles of the additive agent are dispersed into the mass of the combined air streams before the air moves forwardly through the two sets of circular series of diStributing ports 30 and 31 into air chamber 27.

The natural turbulence of the air flow tends to complete the uniform distribution of the minute quantity of the additive material throughout the full body of the air in chamber 27 before the air travels down the annular series of slots 32 in the insert 33 and into the iinalair distributing chamber 34. The slots 32 converge radially toward the longitudinal axis of the spray nozzle and also are formed with their longitudinal axes angled laterally or circumferentially at thirty degrees to that of the spray nozzle. The slots therefor give the air stream a whirling action as it enters chamber 34. The insert 33 functions further to position the air cap 11 in alignment and in proper spacing with the material discharge tip 15.

From chamber 34 the air is discharged through the annular discharge opening 35 into immediate atomizing relation with the coating material issuing fromv tip 15; The whirling movement of the atomizing air emitted from opening 35 helps draw the coating material into more intimate contact with the air. The air is also discharged through the circular series of bores 36 and 36a to fonn jets striking the material stream after the impingement of the air from annular opening 35 upon the material stream.

In a preferred embodiment of this invention bores 36 are angled at twenty-tive degrees toward the nozzle axis and bores 36a are angled at forty degrees thereto. Accordingly the jets of air from bores 36a strike the material stream before those from bores 36. Better penetration and agitation of the material stream results because with them all directed at the same angle and meeting the material stream at the same time the jets would to some degree counteract each other with all simultaneously pressing the stream inwardly.

Y The jets are closely enough positioned and sufciently similar in force to produce a symmetrical spray pattern in spite of the staggered angles. For the high production deposit of polyisocyanate expansible resins for which this spray nozzle is particularly designed and presently employed the round pattern developed is very satisfactory.

As shown schematically in Figure 3 the passage 39 receives the additive agent from inlet 8 and delivers it to valve chamber 40, the outlet from which is controlled by valve 9. From chamber 40 the additive agent enters metering chamber 41. The outlet of chamber 41 is restricted so that the additive agent flows therefrom in only a iine stream form through the injection passage 28 and into mixing conuence with the -air traveling along branch passage 20. The schematic illustration of Figure 3 is intended to correspond with the arrangement of passages disclosed in detail in my earlier application referred to above.

In one size nozzle of the subject design, and spraying with air at sixty pounds of pressure, sixty ounces of a polyisocyanate resin may be applied per minute with four and eight tenths ounces of catalyst intermixed with the resin. This particular size of nozzle consumes twentyfour cubic feet of free air per minute at the designated pressure.

Traveling through the spray gun in compressed form j this air occupies four and seven tenths cubic feet which is equivalent to 4,480 ounces. It may be seen therefore by comparing volumes that the four and eight tenths ounces of additive agent introduced into the air per minute represents less than one nine hundredths of the air volume. This quantity is so minute that it does not affect the power of the air to atomize the coating material and is itself so iinely dispersed in the air that it is capable of having activating contact with the smallest particles into which the resin coating material is comminuted by the atomizing air.

It is apparent from the preceding that the atomizing air carrying the small increment of catalytic agent is repeatedly baiied, subdivided and recombined in order to insure uniform and full commingling of the air and catalyst.

The air is also given a whirling motion that is retained in that portion issuing from the annular outlet to beneficially influence the primary atomizing action. The whirling effect, not considered necessary in the air jets discharged from bores 36 and 36a, is probably quite completely eliminated therefrom by the small diameter and comparative elongation of the bores.

In one form of the invention bores 36 and 36a have a diameter of .025 inch. In another embodiment of greater capacity their diameter is increased about fty percent and the number is enlarged to circumscribe a coating material outlet tip of expanded capacity. In this latter design the agitating and mixing action of the jets is augmented by directing them more sharply toward the coating material stream at angles in the range between fortyiive and sixty degrees.

The air cap 11a shown in Figure 6 has an elongated discharge tube 44. The spray nozzle of this invention incorporates such an air cap for use particularly in depositing expansible resins in cavities. The tubular extension serves as a guide and in conning the spray discharge brings about a quicker inception of the reaction between the resin and the catalyst with the curing of the resin starting within the tube.

With the spread of the spray discharge restrained, there is a lower loss of catalyst by evaporation or dilusion with the air. As a consequence the catalyst is more cornpletely utilized and a lesser amount is required. Since it is usually an expensive ingredient, the saving involved is important.

Through the means illustrated and described a spray nozzle design has been created that has great and efficient capacity for utilizing air impregnated with a minute quantity of an additive agent to rapidly atomize viscous resins and similar materials and to intimately mix therethrough the additive agent carried by the air.

As indicated herein various sizes, number, and angles of jets in the annular series may be utilized and are herein the province of this invention.

What I claim is:

1.' A spray 4nozzle for atomizing a material with compressed air and intimately mixing with the material an additive agent carried by the compressed air, said spray nozzle having a discharge tip for the discharge of material having a conical outer end, and means for discharging atomizing air carrying an additive agent in surrounding relation to the tip, said means including an inner insert member tting around the conical outer end of the tip, there being a series of circumferentially spaced air passages through the inner insert member, and said means also including an outer air cap member in re taining contact with the inner insert member, the outer air cap member -being shaped to define an annular chamber forwardly of the inner insert member, said annular chamber being of at form with its axial dimension less than the radial distance between its inner and outer diameters, and -a restricted annular air outlet around the outer end of the tip in direct communication with said annular chamber, there also being a series of air outlet ports in the outer air cap member disposed in surrounding relation to the annular air outlet and also in direct communication with said annular chamber.

2. A spray nozzle according to claim 1 in which the circumferentially spaced air passages in the inner insert member are angled to give the atomizing air and the additive agent carried thereby a whirling motion upon reaching the annular chamber.

3. A spray nozzle according to claim 1 in which there is an elongated tubular extension confining the spray discharge for at least several inches beyond the outer end of the tip and the air discharge outlet.

References Cited in the le of this patent UNTTED STATES PATENTS 2,050,368 Neeley Aug. 11, 1936 2,511,626 Einbecker June 13, 1950 2,740,670 Harder Apr. 3, 1956 2,779,689 Reis Jan. 29, 1957 2,786,716 Peeps Mar. 26, 1957 2,823,143 Upperman Feb. 11, 1958 FOREIGN PATENTS 566,543 Great Britain Ian. 3, 1945

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