Paint gun

Application filed October 18, 1924. Serial No. 744,334.

This invention relates to coating apparatus, and with regard to certain more specific features, to spray guns for . applying liquids as a coating to surfaces.

Among the several obj ects of the invention may be noted the provision of apparatus for spraying liquids such as paints, varnishes and the like, and more especially quick. drying kinds of these liquids; and the provision of 10 means for preventing the formation of air bubbles in the coating material as it is sprayed. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the 15 features of construction, combinations.of elements and arrangements of parts, which are exemplified in the description hereinafter in connection with the accompanying .drawings, and the scope of the application. of 20 which will be indicated in the following claims. . .

In the accompanying drawings, in which is illustrated one of various possible embodiments of the invention;

Fig. 1. is a side elevation of the spray gun assembled with parts broken away;

Fig. 2 is a front view of the nozzle; and.

Fig. 3 is an enlarged longitudinal section of the nozzle tip and nipple showing the 30 nozzle casing adjusted forwardly.

Referring now more particularly to .Fig. 1 of the accompanying drawings there is illustrated at 1 a body for the gun. This body is provided longitudinally with a paint or 35 material passage 3 and. a compressed air passage 5. Each passage, is enlarged at its rearward opening to receive a valve mechanism.

At the rear of the body 1, and screwed substantially upwardly therein, are two supply 40 pipes, 7 and 9, one for air and one for spraying material under pressure. The material pipe 7 is located forwardly of the air pipe 9 and is adapted to be capped with,a dead-end nipple 11, the use of which will appear later. 45 These pipes 7 and 9 are enclosed by a grip 13 which is held up against the body 1 by nuts 15 and 17. An air supply line 19 of flexible material is coupled to the air pipe 9 by means of the nipple 21. A guard. 23 extending rear50 wardly from above the grip and on the body prevents the head from slipping upwardly from said grip.

The material supply pipe 7 communicates with the material passage 3 by means of the bore 25 which is offset vertically to pass the 55 air passage 5 untouched, and is closed at its upper end by the plug 27. The air supply pipe 9 communicates with the air passage 5 by means of the bore 29. The described arrangement for the passages lends itself .to 60 easy manufacture.

In the present embodiment liquid under . pressure may be supplied to the passage 3 through the pipe 7 by uncoupling the deadend nipple 11 and fastening a flexible liquid 65 supply'line similar to the flexible air line 19.

However,. inasmuch as quick-drying. liquids are seldom mixed in large enough batches to warrant the use of an independent reservoir, it is intended to provided a small 70 reservoir on the spraying apparatus itself.

An upwardly extending lug 31 is provided on the body 1, and is bored at 33. to meet the material passage 3. To this lug is threaded the reservoir cup 35. This cup 35 supplies 75 liquid to the material passage 3. It is provided with a cover 37 which may be clamped down on the cup 35 by means of cooperation between the wedges 39 on the downwardly extending ears 41 of the cover 37 and the 80 slanting lugs 43 of the cup 35. ..It is clear that this cooperation may be brought about by first placing the cover 37 on the cup 35 and then twisting said: cover to the left. A sealing gasket 45 placed in a groove in the cover 85 becomes interposed between said cover and the cup, thus preventing a liquid therein from drying.

The material and air passages 3, and 5, respectively, end forwardly in a nozzle cylinder 90 47 formed at the forward end of the gun (Fig. 1). The material passage 3 is threaded at its forward end within this cylinder 47 and receives the nipple 49 which nipple contains the passage 51 as a continuation of the 05 paint passage 3. . The details of this nipple will be described later.

Around the nozzle cylinder 47 is placed the snugly fitted nozzle casing 53 flanged outwardly at 55 (see Fig 1). This flange abuts loo the threaded ring 57 over which ring 57 is forced with a press fit, the flanged outside ring 59. A flange 61 on ring 59 cooperates with flange 55, permitting the latter to turn

1,703,384 freely with respect to the rings 57 and 59, Avhich rings are one piece to all intents and purposes. The ring 57 is provided with an outwardly extending stop-flange 63 for stop5 ping the pressing on of ring 59 when the proper tolerance for easy rotation of flange 55 has been obtained. When the threaded ring 57 is screwed to the nozzle cylinder its rotation in screwing it on, causes a longitudi10 nal movement of the nozzle casing 53 on the nozzle cylinder 47 without necessarily causing said casing to rotate. Rotation of the nozzle casing on the nozzle cylinder is, however, free to be accomplished by other means.

The forward encl of the nozzle cylinder or casing 53 tapers inwardly forming the air chamber 65 which receives its air supply from the passage 5. As will be described later, some pressure will build up in this chamber 20 65 so that a seal is needed between the casing and cylinder. This is accomplished by cutting a groove at the end of tlie cylinder and placing a soft gasket 67 therein. Against this gasket is placed a forwardly dished me25 tallio washfei· 69 having a central hole therein adapted to receive the nipple 49. A shoulder 71 on the nipple tends to flatten out the dish shape of the washer as the nipple is screwed home in the end of the paint passage, thereby 30 forcing the edges of the washer to exert a local pressure on the gasket 67 and causing it to seal the joint betAveen the casing and cylinder. The washer has a hole 73 cut therein to permit air to pass from the passage 5 to the 35 chamber 65.

As before described, tlie forward end of the casing 53 tapers inwardly to a nozzle tip 75. This tip 75 comprises a centrally bored plug Avhich is forced into the forward 40 end of the casing. Said central bore is adapted to receive snugly, a projecting cylinder 77 of the nipple 49. The tip 75 is also provided Avith air discharge ducts, 79 and 81, Avhich end forwardly in such a fashion as to direct ,15 air forwardly and convergingly toward the center of the nozzle. These ducts are arranged preferably at 180 degree intervals, there being Iavo of them.

As indicated the projecting cylinder 77 of 50 the nipple 49 extends slidably into the tip 75.

This cylinder 77 is provided Avith a forwardly projecting cylindrical teat 83 bored to meet the passage 51 and provided Avith a cleaning plug 85 in the bore. This plug 85 is integrally 55 formed with the valve plug 87 on the material valve stem 89. This stem 89 and the two plugs 87 and 85 are capable of being Avithdraivn rearwardly to the dotted line position shown in Fig. 3, thus opening the material co passage of the nozzle. A guide spider 91 holds the assembly within the nipple in alignment.

The material valve stem 89 and a stem 93 of the air valve have adjustable nuts 95 and 05 97 mounted rearwardly thereon. The nuts engage saddle straps 98 and 100, reaching around the gun and pivoted to the trigger 99Avhich is itself pivoted to the body 1 at 101. When the trigger 99 is pressed the valve stems are caused to be drawn reanvardly. 70 This is brought about by means/ of the engagement between the saddle portions 103 and 105 of the straps and enlarged knurled portions of the nuts 95, 97. However the saddle portion 103 of the material valve strap 75 rides on a cylindrical portion 107 of the nut 95 before striking the enlarged portion mentioned thus permitting the air valve to be opened first and obviating the possibility of spreading any unatomized paint when start- so ing the apparatus.

The operation of tlie device is as follows:

The nozzle may be adjusted as shoAvn in Fig. 1, i. e., with air ducts 79 and 81 impinging on the teat 83 and vertically positioned 85 Avith respect to one another. The cup 35 is filled Avith liquid. Upon pressing the trigger, the air valve is immediately opened, inasmuch as the saddle portion 105 was already in contact Avith the enlarged portion of nut 90 97. Air then flows from the flexible conduit 19, through pipe 9, the air valve, duct 5, through chamber 65, and out of the ducts 79, 81, to be impinged on the teat 83. Incidentally, as it leaves the ducts it exerts an aspi- 95 rating effect.

As the trigger is further pressed the saddle 103 rides over the cylinder 107 and contacts with the enlarged portion of nut 95 thereby opening the material valve. The ma- 100 terial under a head or pressure finds its way out of the teat 83 and is picked up by the aspirating air, atomized and throAvn on the surface to be covered. Inasmuch as only tAvo ducts such as 79 and 81, beside the symmetri- 105 cal central ejection from betAveen cylinder 77 and plug 75 are present, the air exerts a distorting effect on the issuing circular section of paint causing it to take a desirable elliptical or ovate- shape. The teat 83 counteracts no this effect someAvhat. If the full effect of flattening the spray is wished for. Avithout counteraction, it is only necessary to force tlie casing forwardly to a position such as shown in Fig. 3, Avhereupon the teat becomes inef- 115 fective and the spray becomes greatly eccentric instead of only slightly so.

If desired the ducts 79 and 81 may be adjusted to a horizontal relationship thus giving a vertically elliptical spray instead of the 120. horizontally elliptical one to be expected here.

It should be noted here that the air ducts are close to the point of paint ejection and the expanding air from the ducts therefor forms small vacuum pockets rearwardly of 125 said ejecting air. The pressure on the paint before ejection is, by gravity or otherwise, made just enough to overcome line friction and thus bring it to the nozzle independently or any aspirating action. At this point, the 130

1,703,384 body, a nipple in communication Avith said 65 reseiwoir, a longitudinally and rotatably movable nozzle tip slidably cooperating with said nipple, and. ducts in said tip adapted to eject an aspirating and distorting stream, of air ahead of said nipple, and a teat on said 70 _:nipple adapted to counteract, the distorting effect of the air stream when said nozzle tip is in. a retracted position.

rii. In a spray gun the combination of, a body, a reservoir mounted on and above 75 said body, a nipple in communication with said reservoir, a valve in said nipple, a teat on said nipple and a cleaning plug in said teat integral with said valve, a nozzle tip slidably cooperating with said nipple adapt- 80 ecl to cooperate with said nipple, ducts in said tip adapted to eject an aspirating and distorting stream of air ahead of said nipple and upon or ahead of said teat according to adjustment. . ; 85

7. In a spray nozzle the combination of a cylinder, a casing over said cylinder, a tip on said casing means for sealing the joint betAveen said cylinder and casing, an ejecting nipple adapted to make the sealing means ⁹⁰operable and cooperating slidably with said tip. . _

8. In a spray nozzle the combination of a cylinder, a easing over said cylinder, a tip on said casing means for sealing the joint ⁹⁵between said cylinder and casing, an ejecting nipple adapted to make the sealing means operable and cooperating slidably with said tip and a valve Avithin said nipple.

9. In a spray nozzle the combination of. a 100 cylinder, a casing over said cylinder,, a tip on said casing means for sealing the joint between said cylinder and casing, an ejecting nipple adapted to making the sealing means operable and cooperating slidably with said 105 tip and a projecting teat on said nipple adapted to extend forward of said tip.

10. In a spray nozzle the combination of a cylinder, a casing over said cylinder, a tip _:on said cylinder, passages in said tip adapted no to eject air forwardly and angularly toward a common center thereby creating a low pressure area rearwardly, means for sealing the joint betAveen said cylinder and casing, a delivery nipple adapted' to making the seal- ¹¹⁵ing means operable, cooperating slidably . with said tip and adapted to deliver .material into the said low pressure area.

11. In a spray nozzle the .combination of a cylinder, a easing over said cylinder, a tip ¹²⁰on said cylinder, passages in said tip adapted . to eject air forAvardly and angularly toAvard a common center thereby creating a Ioav pressure area rearAvardly, means for sealing the joint between said cylinder and casing, ¹²⁰a delivery nipple adapted to making the sealing means operable, cooperating slidably with said tip and adapted to deliver material paint is drawn outwardly and mingles Avith the jet of air Avhich draws it. In previous type's of sprayers, the air jets form no vacuum pockets but merely play on a pressure ejected stream of paint. This results in a. rolling up and swirling of the paint stream as it strikes the impinging air stream with the result that air bubbles are. engendered. These are detrimental to surfaces which should have smooth coatings., .

From the above it will be seen that the several objects of the invention are attained and other advantageous results achieved.

As many modificati ons of the embodiments 15 above illustrated might be made Avithout departing from the spirit of scope of the present invention, it is intended that the above description and accompanying drawings and claims shall be interpreted as illustrative and so not in a limiting sense.