US3485453A

US3485453A - Dual component spray gun

Info

Publication number: US3485453A
Application number: US703139A
Authority: US
Inventors: Donald J Peeps
Original assignee: DeVilbiss Co
Current assignee: DeVilbiss Co
Priority date: 1968-02-05
Filing date: 1968-02-05
Publication date: 1969-12-23
Anticipated expiration: 1986-12-23

Description

D. J. PEEPS Dec. 23, 15969 DUAL COMPONENT SPRAY GUN 2 Sheets-Sheet 1 Filed Feb. 5, 1968 INVENTORI .UUNALD J. PEEPQ.

D. J. PEEPS '3,485,453

DUAL COMPONENT SPRAY GUN 2 Shees-Sheet 2 Filed Feb.

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United States Patent P DUAL COMPONENT SPRAY GUN Donald J. Peeps, Rossford, Ohio, assgnor to The De- Vilbiss Company, Toledo, Ohio, a corporation of Ohio Filed Feb. 5, 1968, Ser. No. 703,139 Int. Cl. B05b 7/12, 7/14, 11/00 Us. c1. 239-422 s claims ABSTRACT 0F THE DISCLOSURE A foam spray head for a dual component spray gun. Fluid and air streams are controlled by a thin, replaceable Teflon valve plate having three valves which are aligned with one air and two liquid passages in a tip adapter. Three serially connected chambers in the tip are aligned with the valves such tha-t air enters the iirst chamber, flows through the second chamber to pick up and mix with one of the liquid components, and then flows through the third chamber to pick up and mix with the other liquid component. The third chamber is connected to a spray nozzle. To clean the spray head, the two liquid component sources are shut off and an airsolvent mixture is forced from the air passage through the serially connected chambers and the nozzle.

BACKGROUND OF THE INVENTION This invention relates generally to an improved gun for spraying coating materials, and particularly, to an improved spray head in a spray gun for plural component coating materials such as urethane foams, epoxies, polyesters, gel coats, and other rapidly reacting chemical materials.

The development and widespread employment of sprayable plastics of various types have created a need for suitable apparatus for applying these materials as a coating on articles in a quick and efiicient manner. These materials cannot be applied in the conventional manner and with conventional spray apparatus since the materials are usually comprised of two or more chemically reactive portions that must be maintained separate from each other until the reaction is intended and desired.

In producing a foam coating, for example, two separate portions are employed. The rst portion contains an isocyanate vehicle, the second portion contains either a polyester or a polyether resin combined with required catalysts, surfactants and a low boiling liquid type blowing agent. When the two portions are combined, an exothermic reaction takes place which changes the liquid blowing agent to a gas, which is entrapped and expands the total mass in the form of a rigid foam. Reaction also causes the mixture to harden. It will be readily apparent that, if the rst portion were combined with any of the second portions before passing through a mixing chamber, foaming and hardening would begin at that point. Even though the reaction were not suiiciently rapid to effect mixing, there would still be the hazard that the combined portions would react Within the mixing apparatus when it is not operating and cause the nozzle of the applicator to become clogged or a ow control valve or other movable part to stick.

In the past, several types of dual `component spray guns have been tried with varying degrees of success. One type of gun had a separate nozzle for each component. The nozzles were aimed to converge on the surface being sprayed. These external mix spray guns had an advantage in that they required very little cleaning after each use since the components were mixed only exteriorly of the spray gun. However, there were problems in that the corn- Patented Dec. 23, 1969 ponents were not as thoroughly intermixed as desired in some cases and the necessity for multiple spray heads or nozzles rendered the guns complex, expensive and bulky.

SUMMARY OF THE INVENTION The dual component spray gun of the present invention includes a conventional spray gun body having an air passage therethrough which is connected to a compressed air source, an attached handle and a trigger, a novel spray head and a conventional spray nozzle. Trigger actuated valves within the gun control ow through the air and liquid passages.

Fittings on the bottom of the spray head are connected to hoses which supply, under pressure, two liquid components which chemically react to form the spray coating. Each of the two liquid components passes through a separate control valve which is actuated by the single trigger. Three passages in an adapter are connected from the air control valve in the gun body and the two liquid component control Valves, through a valve plate to three serially connected mixing chambers in a mixing head.

The valve plate has ilaps cut in it which act as check valves between the mixing chambers and the passages in the adapter. The aps are larger than, and completely cover, the passages to prevent a backow of air or liquid from the mixing chambers into the passages. However, the flaps are ilexible and open under pressure into the mixing chambers to permit a flow from the passages.

The air passage in the tip adapter is connected through the valve plate to the rst of the three serially connected mixing chamber. A rst one of the liquid component passages is connected through the valve plate to the second one of the serially connected mixing chambers where it is admixed with the air. The other of the liquid component passages is connected through the valve plate to the third one of the serially connected mixing chambers where it is admixed with the air-first component mixture. The third mixing chamber is connected through the mixing head to the spray nozzle.

It is an object of the invention to provide a simple and ecient apparatus which will permit coating of articles with an air entrained mixture of two or more separately maintained liquids.

It is another object of this invention to provide an improved spray gun of economical construction, having only `a `single spray nozzle and yet efficiently tand effectively spraying a broad range of plural fluid component materials of both foaming and non-foaming types.

Another object of the invention is to provide an improved check valve means for a plural component spray gun which prevents flow from a mixing chamber into the component supply passages.

Still another object of the present invention is to provide lan improved mixing chamber for a plural component spray gun.

Other objects and advantages of the invention will appear from the following detailed description of 'a particular embodiment thereof, reference being made to the `accompanying drawings.

BRIEF DESCRIPTION OF THE. DRAWINGS FIG. 1 is a side view with parts broken away 0f apparatus embodying the invention;

FIG. 2 is a front view of the lapparatus of FIG. 1;

FIG. 3 is an exploded perspective view of the mixing head showing ya mixing chamber and a valve plate which embodies the invention;

FIG. 4 is a cross-sectional view on line 4 4 of FIG. 2;

FIG. 5 is a cross-sectional view on line 5 5 of FIG. 2;

3 FIG. 6 is a cross-sectional view on line 6 6 of FIG. 5; and

FIG. 7 is a cross-sectional view on line 7-7 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT A specific embodiment of the present invention is shown in the drawings and comprises a spray gun body 12 to which a trigger 14 is pivotally attached in the usual manner. A handle 16 extends from the rear of the body yand carries an air inlet 18 extending therefrom for connection to a conventional source of high pressure compressed air which is used to mix the liquids within the spray gun and to direct the mixture as it is discharged from the spray gun as hereinafter described.

At its front end, the spray gun body 12 carries a fluid control head 20 which surrounds and retains valves for controlling the flow of two liquid components from their respective pressurized sources as hereinafter described. A mixing head 22 is attached to the front end of the fluid control head 20 for mixing the two liquid components and air. A spray nozzle 24 is attached to the front of the mixing head 22 for atomizing the mixed cornponents to form a spray to be deposited on the work.

Air may be supplied to the mixing head 22 in any suitable manner. In the embodiment shown, air ows to the mixing head 22 through the inlet 18 and passages 26 and 28 in the handle 16, -through bore 30 in the gun body 12 and through passage 32 in the uid control head 20. A valve 34 is located between passages 26 and 28 and is opened by the trigger 14 acting on valve stem 36. The valve 34 is held in a closed position by a spring 38 in a recess 40.

Two additional trigger actuated valves `are located 1n the liuid control head 20. The first valve includes a fluid orifice 42 and a cooperating needle valve 44. The fluid orifice 42 and needle valve 44 are located between passages `48 and 50 in the uid control head 20. A first pressurized liquid supply is connected through a standard hose fitting 46 to passage 48. Passage 50 is connected through bore 52 to a iluid chamber 54 lying :between the fluid control head 20 and a tip adapter insert 56 in the mixing head 22. Needle valve 44 is held in a normally closed position by a spring 58 which is retained in an end cap 60. When the trigger 14 is pulled against an adjustable nut 62 which is attached to the stem of needle valve `44, the valve 44 is opened.

A second pressurized liquid supply is connected through a -standard hose iitting 64 to passage 66. The other of the two trigger `actuated valves, which is connected between passage 66 and iiuid chamber 68, includes a primary fluid ti-p 70 and a cooperating fluid needle valve 72. Needle valve 72 is held in a normally closed position by a spring and end cap in a manner similar to that for needle valve 44. When the trigger 14 is pulled, the valve 72 is opened.

The sequence in which the

valves

34, 44 and 72 are opened as the trigger 14 is pulled may be changed by adjusting nuts 62 and 74 which are threadably attached to the stems of needle tvalves 44 and 72 respectively. It is preferable to have the `air control valve 34 open before either of the `

liquid control valves

44 or 72.

The mixing head 22 is attached to the fluid control head 20 with an adapter nut 76. Referring now to FIG. 3, the mixing head 22 generally comprises a tip adapter 78, a valve plate 80 and a chambered element 82 in which tinal mixing of the two liquid components and air takes place. Tip adapter insert 56, which is pressed into the tip adapter 78, forms chamber 54 for the rst liquid and chamber 68 for the second liquid between tip adapter 78 and uid `control head 20. In addition, an air chamber 84, formed between tip adapter 78 and uid control 96 in tip adapter 78 lead from the first liquid chamber 54 and the second liquid chamber 68, respectively, to the flat surface 92. Three dowels 98 extend from the flat surface 92 and cooperate with aligned holes 100 through valve plate and holes 102 bored into the chambered element 82.

Valve plate 80 is preferably made from a uorocarbon polymer, e.g. polytetrauoroethylene, which is iiexible. When valve plate 80 is aligned on dowels 98, three fiexible valve aps 104:1, 104b and 104C struck from the body of the valve plate, completely cover the cylindrical air hole and the two

liquid passages

94 and 96 at the surface 92 of the tip adapter 78.

Three serially connected mixing chambers 106, 108 and are milled into the rear surface 112 of the chambered element 82. When the chambered element 82 is aligned on the three dowels 08, the three mixing chambers 106, 108 and 110 are aligned with the three valve flaps 104a, 104b and 104C, such that each exible valve flap opens into its associated mixing chamber. Accordingly, the valve fiaps 104 permit fluid liow from the passages while prohibiting reverse ow from the mixing chambers into the passages.

The mixing chambers are serially connected such that air ows from the cylindrical hole 90 in the tip adapter 78 past the check valve flap 104a and into the first mixing chamber 106. A channel 114 connects the first mixing chamber 106 with the second mixing chamber 108 where the air is mixed with the first liquid, which is forced from passage 94 past its check valve ap 104!) into the second mixing chamber 108. A channel 116 connects mixing chambers 108 and 110. The second liquid is forced from passage 96 past the last check valve iiap 104e into the third mixing chamber 110, Where it is mixed with the airfirst liquid mixture from mixing chamber 108. The third mixing chamber 110 is connected by a channel 118 to a bore extending through the center of the chambered element 82.

An adapter nut 122 is used to attach a conventional spray nozzle 24 to the end of the chambered element 82. The air, first liquid component and second liquid cornponent mixture passes from the bore 120 through the spray nozzle 24 where it is dispersed to form the spray coating on the work.

After the spray gun is used, it is necessary to clean out all passages and chambers containing the mixed rst and second liquids. It is particularly important that the gun be cleaned immediately, since many chemicals used have a rapid reaction and harden soon after mixing. rThe spray gun is cleaned by injecting a solvent into the air supply and closing the two liquid supplies. The solvent may be mixed with air either exteriorly of the gun or may be injected directly into bore 30 extending through the gun body 12. The normal air supply or solvent pressure alone forces the Solvent through the serially connected mixing chambers 106, 108 and 110, the innterconnecting channels 114 and 116, channel 118, bore 120 and the spray nozzle 24. It is apparent that the novel serial arrangement of al1 chambers, channels, bores and the spray nozzle permits easy and rapid cleaning of the gun.

lf the operator fails to clean the spray gun after use, it is easily disassembled for cleaning by removing the adapter nut 76 and the adapter nut 122. Both the spray nozzle 24 and the valve plate 80 are inexpensive and easily replaced. The mixing chambers 106, 108 and 110, the bore 120, and the connecting

channels

114, 116 and 118 in the chambered element 82 are completely exposed for ease in cleaning.

The embodiment herein described clearly can be modied to handle coating materials having more than two components. While the invention has ben described in connection with a specific form and disposition of the parts, it should be understood that it is capable of numerous modifications and changes without departing from the scope of the appended claims..

What I claim is:

1. A plural component spray gun comprising a body having air rst and second liquid passages and a spray head, said spray head comprising: a thin replaceable valve plate attached to said body, said valve plate having three flexible flaps cut therein such that each flap covers a different one of said passages, a mixing head attached to said lbody and lying against said Valve plate, said mixing head having a hollow mixing chamber connected through said valve plate to receive air and both liquids from said passages, a spray nozzle, and means connecting said spray nozzle to said mixing chamber.

2. The plural component spray gun of claim 1 wherein said mixing chamber comprises first, second and third serially connected chambers, said air passage being connected through said valve plate to said first chamber, said rst liquid passage being connected through said valve plate to said second chamber, said second liquid passage ybeing connected through said valve plate to said third chamber, and said spray nozzle being connected to said third chamber.

3. The plural component spray gun of claim 2 further including means for forcing an air-solvent mixture from said air passage through said valve plate, said serially connected sub-chambers and said spray nozzle for cleaning said spray head.

4. In a plural component spray gun comprising a body having a valve controlled air passage connected to a source of compressed air, a spray head and a spray nozzle, an improved spray head comprising:

an adapter, said adapter having an air passage therethrough connected to said valve controlled passage, a rst liquid passage connected to a first liquid component source and a second liquid passage connected to a second liquid component source,

a thin replaceable valve plate attached to said adapter, said valve plate having an air check valve covering said air passage, a first liquid check valve covering said rst liquid passage and a second liquid check valve covering said second liquid passage,

a mixing head attached to Said valve plate, said mixing head having first, second and third serially connected chambers, said rst chamber being connected to receive air from said air check valve, said second chamber being connected to` receive the first liquid from said tirst liquid check valve and said third chamber being connected to receive the second liquid from said second liquid check valve, and

means connecting said third chamber to the spray nozzle.

5. The improved spray head of claim 4 wherein said replaceable valve plate is constructed vfrom a fluorocarbon polymer and wherein said valves constitute aps cut into said valve plate such that each flap completely covers its associated passage.

6. The improved spray head of claim 4 including means for inducing an airsolvent mixture into said air duct whereby said air mixture is forced serially through said first, second and third serially connected chambers and through the spray nozzle to clean the spray head.

7. In a spray gun for discharging plural component coating materials having a body with fluid passages for each of the components, a mixing chamber connecting the passages and a spray nozzle connected to the mixing chamber, an improved check valve for preventing flow from the mixing chamber into the passages, comprising: a at flexible valve plate attached between the fluid passages and the mixing chamber, said valve plate having check valves therein for each of the uid passages, and said valves comprising ilexible flaps cut into said valve plate such that each flap covers a different one of the passages.

8. In a plural component spray gun including a body having first, second and third fiuid passages, a spray head and a spray nozzle, an improved spray head comprising: a mixing head having first, second and third serially connected chambers, said first chamber being connected to receive air from the first passage, said second chamber being connected to receive a first liquid from the second passage and to mix the first liquid with the air, said third chamber being connected to receive a second liquid from the third passage and to mix the second liquid with the air-first liquid mixture, and means in said mixing head for connecting said third chamber to the spray nozzle.

References Cited UNITED STATES PATENTS 2,044,720 6/ 1936 Fletcher 239-422 X 2,895,685 7/1959 Peeps 239-422 X 2,971,700 2/ 1961 Peeps 239-422 X SAMUEL F. COLEMAN, Primary Examiner