US2724615A

US2724615A - Spraying device

Info

Publication number: US2724615A
Application number: US192526A
Authority: US
Inventors: Ariotti Guido
Original assignee: Glidden Co
Current assignee: Akzo Nobel Paints LLC
Priority date: 1950-10-27
Filing date: 1950-10-27
Publication date: 1955-11-22
Anticipated expiration: 1972-11-22

Description

SPRAYING DEVICE Filed Oct. 27, 1950 United ...States Patent; @fine 2,724,615 Patented Nov. 22, 1955 glnments, to The Glidden Company, a corporation of ApplicationOctober 27, 1950, Serial No. 192,526

1 claim. (Cl. 299`140.1)

"This invention relates to spraying apparatus and `more particularly `to apparatus for spray application of `specialty inishes.

For obtaining special `effects in `coatings of paint, lacquer, 'enameland `the like, it is sometimes desirable to spray two coating compositions simultaneously upon the object to be coated in such manner that the individual droplets of the two compositions are thoroughly interdispersed while avoiding theformation ot' single droplets containing both compositions -in admixture. `By way `of illustration, an effect simulatingthe appearance of hammered metal may befobtained by spraying simultaneously a line mist of a relatively fluid coating containing metallic pigment `and coarser `droplets of a `more viscous clear coating, the droplets being well dispersed in the mist as the sprayreaches the work but not to the extent that the two coatingslare coalesced within the spray particles. It, instead of metallic and clear coatings, the two coating compositions contain i colored pigments mottled and speckled effects are obtained. t

An object `of this invention is toprovide a noveltype of `'spray apparatus. i j

Another object is to provide a spray gun adapted to deliver, from a single nozzle, a spray containing two coating compositions, each in the form of line droplets,

` said droplets being thoroughly interdispersed in the spray.

A still further object is to provide a spray gun in which two essentially unmixed coating compositions are introduced through a common orifice into an atomizing air stream.

The above and other objects will become apparent in the course of the following description of the invention and the appended claim.

The spray gun of the present invention, wh-ich fulfills the above object, comprises an air cap with valved means for supplying air under pressure thereto; a tluid tip containing two ducts for communication with separate reservoirs supplying coating materials and a single outlet port centered in the discharge opening of the air cap; a needle valve operable to close said ducts and said port simultaneously; and means for manually op erating said needle valve and said valved means for supplying air under pressure to the air cap.

One form which the invention may assume is exemplified in the following description and illustrated by way of example in the accompanying drawings in which:

Figure 1 is a vertical sectional view of a spray gun embodying the invent-ion; and

Figure 2 is a horizontal section along the line 22 of Figure l; with the main needle valve in retracted posiltion.

In the drawings like reference numerals refer to similar parts.

The spray gun comprises an a-ir cap 11, a tluid tip 12 and needle valve 13, with air and fluid connections connected and controlled as hereinafter more fully described.

The air cap 11 is fitted over the end of the body 14 of the spray gun and held in place by the threaded retaining ring 15. It forms a small `annular .air chamber 16 about the forward portion of the fluid tip 12 and is provided with a discharge opening 17. Means for supplying air under pressure to the air cap` is provided through duct 18 which communicatesdirectly with chamber 16 and, by means of valve 19 and passageway 20, with a source (not shown) of compressed air. In the particular embodiment illustrated the air cap is provided with air jets 21 (shown in Fig. 2) for modifying the spray pattern in manner well known in the art, air for these jets being controllably divided from the main air stream by the adjustable needle Valve 23. APassageway 22 delivers a-ir to annular chamber 24 and thence to the jets. Valve 19 is maintained in a normally closed position by the coil spring 26 and is manually operable by a mechanism to be described hereinafter.

The fluid tip, designated generally by 12, is threaded directly into the body of the spray gun in such `manner that its outlet `port 31 is centered in the discharge -opening 17 of the air cap, leaving an annular opening Sfer the discharge of air. Within the tip, the outlet port communicates directly with a tapered valve seat 36 com tain-ing openings from uid ducts 32 and 32 ("see Fig. 2) so placed that needle valve 13 may operate to close them simultaneously, and at the same time substantially till the free space between said openings `and the forward end of the said outlet port. The

ducts

32 and 32 communicate separately with coating composition reservoirs (not shown) by means of conduits, one of which is shown as 33, said conduits terminating at

openings

34 and 34 into said ducts. ln the embodiment specifically illustrated needle valves 3S and 3S' are .p1-o4 vided at the junctions of said conduits and said ducts Vfor the purpose of separately regulating and proportioning the iiow from the two reservoirs.

Near the "forward end of the needle valve 13 is a tapered section l1 ground to match valve seat 36 and simultaneously close

openings

32 and 32. The cylin drcal end 50 of the needle ts loosely in the outlet port 31 so that, in the closed position there is no substantial opening in the tluid tip 12 where residues of the two coating compositions are in contact.

The valve is held in a normally closed position by the coil spring 42, the tension of which may be adjusted by the screw 43. The shaft of the valve 13 passes axially through a cylindrical opening in the body of the gun fitted with a packing gland at 4d to prevent leakage of fluid from the tluid tip 12 along the shaft. The shaft of the valve is provided with an enlargement d'5 operating, by means more fully described hereinafter, to rev tract the needle valve when the trigger 43 of the spray gun is pulled, thereby compressing coil spring 42, simulta neously connecting

ducts

32 and 32 with the outlet port 31 in the iluid tip 12 and opening said outlet port.

In the embodiment illustrated,

valves

19 and 13 are manually operated by means of trigger 48. The trigger depends from a yoke the arms of which are shown at 47 and 47', which is hinged upon a pin 49 through the upper portion of the body of the gun, The trigger rests directly against the stem 25 of valve 19 in such manner that when it is pulled the valve is opened immediately. A slotted cross bar 46 joins the arms 47 and fl-'7' of the trigger yoke, the shaft of needle valve 13 passing through the slot in such relation that when the trigger is pulled the shoulder of enlargement 45 is engaged by the cross bar 46 to retract the needle valve 13. kln the preferred embodiment the length of valve stem 25 and the position of enlargement 45 are so adjusted that when the trigger 48 is released and is thrust forward by the pressure of coil spring 26, there is a slight, but definite clearance between enlargement 45 and cross bar 46. By this means 1t is assured that when the trigger is pulled air is sup plied to the air cap under pressure in advance of the opening of the fluid ducts; and that, upon release of the trigger air is supplied after the fluid ducts and outlet port are closed to atomize the last of the iiuid delivered therethrough.

Coating compositions may be supplied to the conduits one of which is shown at 33 under the same or different pressures greater than atmospheric, or may be aspirated by the air stream about the outlet port 31, from the reservoirs (not shown) at atmospheric pressure. Between usages the needle valve 13 closes both openings 32 and 32' and substantially fills the free space in the fluid tip between said openings and the forward end of outlet port 31. Accordingly, there is practically no residue within the gun of the separate coating compositions in contact with each other and diffusion of one composition into the other does not occur. When the needle valve is retracted thecompositions flow simultaneously along the cylindrical tip thereof outward through port 31 and are broken into a spray by the air stream issuing from the discharge opening 17. The extremely short path between the point of convergence of the two uid streams and the point of atomization assures a minimum of mixing of the two compositions in gross, and the presence of both components in the single stream leaving the outlet port assures that droplets of the two shall be intimately intermingled in the spray formed by the impinging air stream. The work being coated thus receives a 'spray of intermingled droplets in the proportion desired immediately upon operation of the trigger with no loss of time and waste of materials while mixed residues from previous yoperations are cleared from the tip and from any opening common to the two supply sources.

The device is particularly useful for the simultaneous application of coating compositions of widely differing viscosities. The compositions may be supplied to the fluid tip at widely diering pressuresto overcome differences in their resistance to flow through the passageways, and the proportioning may be further controlled by means of the regulating

valves

35 and 35. The positive shutoi action at the duct openings assures that any pressure differential on the two coating compositions cannot force a movement through the device from the high pressure to the low pressure side.

The invention is not limited to the specific features of the embodiment described in detail hereinbefore but includes within its scope all modifications thereof which come within the scope of the following claim.

What is claimed is:

A device for simultaneously spraying two coating materials from a single nozzle which comprises an air cap provided with a discharge opening and valved means for supplying air` under pressure thereto; a iluid tip centered in said cap, said tip containing a single outlet port in the form of a `short cylinder centered in said discharge opening and communicating at its inner end with an inwardly flaring conical valve seat, and two ducts terminating in diametrically opposed openings in said valve seat adjacent to said cylinder for conducting said coating materials to said outlet port; a needle valve containing a conical section shaped to match said valve seat and a cylindrical tip tting loosely in said outlet port, whereby in its closed position said needle valve simultaneously closes both openings from said ducts and substantially lls the free space between said openings and the outer end of said outlet port, and -in its open position said needle valve cooperates w-ith said valve seat and the inner portion of said cylinder to provide a passageway of annular cross-section from said ducts to said outlet port; and means for operating said needle valve and said valved means for supplying a-ir.

References Cited in the tile of this patent UNITED STATES PATENTS 1,774,694 Bateman Sept. 2, 1930 1,837,861 Green et al Dec. 22, 1931 2,504,116 Downs Apr. 18, 1950 2,532,187 Paasche Nov. 28, 1950