US 2356944 A
Description (OCR text may contain errors)
Aug. 29, 1944.
D. J. PEEPS -SPRAY NozzLE Filed Dec. 1, 1941 e. Manno@ 1NVENTOR. Donald J. Peeps ATTORNEY.
Patented Aug. 29, 1944 SPRAY NozzLE Donald J. Peeps, Toledo Ohio, assigner to The De Vilbiss Company, Toledo, Ohio, a corporation of Ohio Application December 1, 1941, Serial No. 421,140
This invention relates to spray nozzles for spray coating devices using air for atomizing the coat-y ing material and more particularly to such nozzles designed for applying a uniform coating of material upon varied surfaces such as the interior of a hollow article. 1
There have always been diiliculties attending the application of a spray coating rapidly, uniformly and eiiiciently to the interior surface of containers, shells, electric light bulbs and other hollow articles. Among the contributing factors is the restricted space ordinarily available in the cavity to be coated, for the manipulation of the spray device. A small, special and expensive nozzle has accordingly been required in nearly all cases. The design of nozzle heretofore generally utilized, discharges a narrow pattern of spray particles. Such a restricted discharge limits the speed of application and the extent of interior surface which may be coated`V effectively. The operation of this nozzle is not eflicient under the effect of the deposit lof excess spray particles which is inclined to collect around its discharge ports. This is objectionable as defects in the coating applied to the surface of al cavity are not easily discovered.
The principal purpose of my invention is to provide a spray nozzle simple and inexpensive in design, compact, and which is capable of discharging a substantial volume of coating material and applying it rapidly and uniformly without interruption over variously faced surfaces such as the interior of a hollow article.
The essence of the invention which renders the above purpose possible of accomplishment resides in the utilization of a spray nozzle of the design inmwhich the air and coating material are mixed prior to their discharge and the provision in such a nozzle of a plurality of cooperative slotted discharge ports.
`Heretofore slotted nozzles have been designed to give a fan shaped spray like that discharged shaped spray has been directed at various angles toward the surface to be coated. In some few instances a round spray has been utilized. This has proved quite satisfactory for coating the inside of pipes or tubes having a small diameter. There has been a design of nozzle that was developed to take care of this specic type of surface. This is the nozzle known as the 360 angle spray which discharges material from an annular slot circumscribing the nozzle and coats the full inner surface of a tube if drawn thru it. It has been found, however, that this type of spray is not fully reliable as far as quality of finish is concerned and for that reason it can not be used for all work of this sort. This is apparently due to the fact that the material is not uniformly distributedalong the discharge slot.
In order to bring out what has been previously accomplished in this general eld it may be well to mention some of the more pertinent patents. Among them is Murray Patent No. 1,553,709 which shows a slotted nozzle of more or less standard design which discharges a fan shaped spray. Downs Patent No. 2,228,226 relates to a later type of slotted nozzle in which the mixture of the air and liquid occurs just in front of the inner edge of the slot. HannonPatent No. 1,936,247 discloses the use of an extension nozzle with a nozzle discharging a round spray for coating the inside of pipes. Downs Patent No. 1,961,481 relates to different forms of extensions forcoating surfaces that are hard to reach. It may be noted that a round shaped spray nozzle is used on the various types illustrated therein and that the spray devices are adapted to the various surfaces to be coated by means of an adjustment of the nozzle which permits it to be directed in any desired direction. Y
Applicants type of spray is altogether diiferent from that discharged from the flooding type of nozzle shown in Peters Patent No. 2,085,765. The discharge openings in the Peters nozzle are not positioned to apply a uniform coating. This is apparent from the number of outlets utilized, the shape of the container being coated, the positioning of the nozzle within the container, the rocking of the container during the operation of the nozzle and the subsequent spinning of the container to distribute the coating material.
In Ferguson Patent No. 1,865,436 a method of coating lamp bulbs is described. In this a side outlet extension nozzle which discharges a round spray is used. This is accommodated to the surfaces to be coated by the way it is introduced into the lamp bulb and by maneuvering it therein during the coating operation.
In the nozzle invented by applicant, the idea of designing a spray nozzle to deliver a spray for a particular contour of surface is introduced. This is of special value where the surface is quite irregular through having a combination of flat, curved or angled sections. When the nozzle is so designed the nozzle movement need not be so involved. For coating the interior of an electric light bulb it may be introduced therein in a straight axial path. By suitable location of the slots the spray may be discharged simultaneously forwardly, rearwardly and to the side in the proper directions to deposit a uniform coating. The spray particles may be distributed evenly, or they may be concentrated by overlapping the slots so as to concentrate more material in certain regions. This is sometimes necessary to provide a suitable coating.
This type of nozzle has been found most valuable in the coating of the inner surfaces of hollow articles, such as, artillery shells, bombs, containers, etc. Shells have quite a variety of shapes but have inner surfaces which generally include a -central cylindrical section. and end portions tapered or rounded from the cylindrical section with occasional ridges or grooves. Previously shells have been coated with side outlet nozzles which discharged in one direction only, the natural flaring of the spray being relied upon to coat the various surfaces presented as the shell was rotated and the nozzle moved axially out of the shell. Such'a spray is limited in size and makes the coating operation a slow one. Further the nature of the spray does not provide even coverage.
With applicants invention the interior shape of the shell is studied and the nozzle is tailormade accordingly. If there is a forward taper, as well as a cylindrical side, one nozzle outlet is directed more forwardly than the other. The shells are rotated while being coated and the nozzle is introduced axially into the shell and the spray is discharged while the nozzle is being withdrawn. In this manner the spray is deposited in a spiral pattern from one end of the shell interior to the other. If there is an inwardly facing shoulder within the shell cavity that requires coating, the second slot may be positioned to spray partially rearwardly as the nozzle is being withdrawn in order that this portion of the surface is properly coated. v
If the shell is sufficiently short, the spraying:
may be accomplished with the nozzle held stationary. In this case the spray pattern extends over the full length of the shell.
It has been found that a single slot will not provide as satisfactory a spray discharge as possible with two slots because the discharge thru a slot of extra large size is not uniform. In a slot that is long or in one that extends back from the forward tip of the nozzle on one side more than the other, the spray material is likely to be discharged more heavily thru one or more portions than through others. This characteristic action should be taken into consideration in the design o-f nozzles with slot orifices. A single slot designed to take care of multiple surfaces would be difficult to construct because of the shape it would have to have. It has been found that a straight cut of a milling cutter approximately 1/2 inch in diameter is very satisfactory for forming the individual slot openings of a multiple slot nozzle. The slots are Ordinarily .020 to .G25 of an,
inch in diameter. The discharge into various directions is secured by positioning the individual slot openings on different faces of the nozzle cap,
Still further and more detailed objects of the invention will appear from the following specication and the accompanying drawing, in which,
Figure 1 is a side elevational view partly in vertical longitudinal section of a spray gun extension with a discharge nozzle embodying the present invention,
Figure 2 is a front elevation of a discharge nozzle cap constructed in accordance with the invention,
Figure 3 is a side elevational View of the discharge nozzle cap shown in Figure 2,
Figure 4 is a front elevation of another form of discharge nozzle cap embodying features of the invention,
Figure 5 is a side elevational Viewv of the cap shown in Figure 4 and,
Figure 6 is a schematic presentation of a cap and the outline of the spray patterns discharged from its two ports against the surface of a cavity.
The extension nozzle, shown in Fig. 1 is mounted on the gun body I by means of the retainer ring 2. The extension section 3 may be of whatever length required. It is composed of an outer air tube 4 and an inner liquid tube 5 with extension piece 5a5 An air tip 6 is fastened to the tube 4 while a liquid tip I is fastened to the liquid tube extension 5a. A liquid shut off needle valve 8 seats within the member 5a. A discharge cap 9 fastens over the ends of tips 6 and 'I providing a mixing chamber I0 for the liquid and air; the mixture of liquid and air then issues from discharge slots I I and I2. The preferred inner shape of the forward end of the discharge cap is spherical; thereby the mixture of liquid and air within the cap has quite equal access to the discharge outlets however placed on the cap.
The discharge cap in Figs. 2 and 3 has a somewhat different combination of slots. It may be noted that their ends overlap at the front point of the cap. Thru the overlapping arrangement a. more concentrated spray pattern is discharged forwardly. This type of cap is used where the article or the nozzle is rotated and the latter is drawn axially from the cavity being coated dur- 1 ing the spraying operation. The spray from one slot sweeps spirally over the surface and is followed by the spray from the other slot, the com lbined spray covering rapidly a surface much larger than either is capable of coating-alone.
r This particular cap is designed for a shell Whose interior includes a main cylindrical section which tapers at the inner end to a point. The slot I3 takes care of the tapered section with some help from the forward end of slot I4. The slot I4 is so positioned that most of its spray is directed of slot I5 extends across the point of the air capand therefor the spray discharge from it overlaps itself on the rotation of the shell. The interior outline of. a section of a shell is indicated at Il in Fig. 6 which also illustrates the pattern discharged by a nozzle with slots similar to those contained in the cap of Figs 4 and 5. If the cov-` erage requirements of the spray pattern warrant it, a third slot may be utilized, for example in the` cap shown in Figs. 2 and 3, at location "A. This slot could be directed rearwardly to take care of an inwardly facing surface such as that covered by the slot I6 in Figs. 4 and 5. It is not often,
however, that the surface involved is so complicated as to require more than two slots.
It has evidently never occurred to anyone previously that multiple slot openings could be used in the manner of this invention. Further, it is not believed that anyone has used a nozzle with a single slot in which the slot has been offset in relation to the axis of the nozzle. A single slot of this type would not be suitable for coating a surface in one plane as the spray pattern is likely to be uneven. In case experiments have been made by otherswith such a slot, they have no doubt been abandoned as it has been the principle in the past to develop nozzles giving fan shaped patterns suitable for coating flat surfaces and accordingly patterns that are uniform throughout their cross sections. While the complete spray pattern from a cap covered by the subject application may be fan shaped, lthe discharge from one slot does not need to join that of the remaining slot or slots although the discharges cooperate with each other in depositing the desired coating. The result secured is like what has been produced previously by separate nozzles used successively.
The air cap designed by applicant is very compact and simple in design. Besides taking up little room 4by itself, by reason of the enlarged scope of the spray pattern it need not be maneuvered about as much within the cavity being coated. Because of the greater scope of the nozzle it is possible to coat many interior surfaces that `formerly were most `difficult if not impossible to coat properly. This is now done in one operation where in the past two or more operations would have been necessary.
While only a few specific embodiments of the invention are shown and described herein, it will be understood that various changes in the size, shape, position and number may be made in the discharge orifices of such nozzles without departing from the spirit of the invention.
Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:
1. In a spray nozzle of the type described, a discharge cap substantially semi-spherical in shape and having discharge slots therein, one slot passing from near the forward end or pole of the sphere to one side thereof and another slot in a plane at an angle to the plane of the rst slot and on the other side of the sphere with one end also extending to the region of the forward end or pole of the sphere.
2. In a spray nozzle of the type described, a discharge cap, semi-spherical in shape, having two discharge slots therein, one slot lying in a plane passing through the longitudinal axis of the discharge cap, the second slot disposed in a plane intersecting the rst mentioned plane, both slots extending rearwardly from the forward end of the discharge cap and on opposite sides thereof.
DONALD J. PEEPS.