US3667682A

US3667682A - Spray gun

Info

Publication number: US3667682A
Application number: US56513A
Authority: US
Inventors: John M Purnell
Original assignee: GROVHAC Inc
Current assignee: GROVHAC Inc
Priority date: 1970-07-20
Filing date: 1970-07-20
Publication date: 1972-06-06
Anticipated expiration: 1989-06-06

Abstract

The disclosed gun for spraying atomized materials includes a housing having an orifice for discharge of the materials and atomizing air vent means associated with the orifice for atomizing the materials upon discharge from the orifice. A movable member and separate orifice closure member are reciprocally disposed in the housing and driven in sequence to provide for the venting of atomizing air through the vent means prior to the discharge of materials through the orifice. Adjustability is provided between the orifice containing member of the housing and the orifice closure member to compensate for wear therebetween, with such adjustability not materially affecting the flow volume of atomizing air. The main body and adjacent enclosure parts of the spray gun housing are secured together by a plurality of longitudinally extending fastening means to eliminate the need for distortion prone tools.

Description

United States Patent Purnell June 6, 1972 [54] SPRAY GUN Primary ExaminerM. Henson Wood, Jr. Assistant ExaminerEdwin D. Grant 72] Inventor. John M. Purnell, Milwaukee, Wis. AHOmey AndruS Sceales Starks & Sawan [73] Assignee: Grovhac, Inc., Milwaukee, Wis. [22] Filed: July 20, 1970 [57] ABS CT The disclosed gun for spraying atomized materials includes a [211 Appl' 56513 housing having an orifice for discharge of the materials and atomizing air vent means associated with the orifice for [52] U.S. Cl ..239/412 atomizing the materials upon discharge from the orifice. A [51] Int.Cl ..B05b 7/12 movable member and separate orifice closure member are Field of Search 415, 417.5 reciprocally disposed in the housing and driven in sequence to provide for the venting of atomizing air through the vent References Clted means prior to the discharge of materials through the orifice. UNITED STATES PATENTS Ad ustability is provided between the orifice containing member of the housing and the orifice closure member to 2,266,365 12/1941 Harrison et al. ..239/4l2 compensate for wear therebetween, with such adjustability 2,553,401 5/1951 Carr ..239/4l3 not materially affecting the flow volume of atomizing air. The 1,305,733 6/1919 Miller 6! main body and adjacent enclosure parts of the spray gun housl.603,902 10/1926 B --239/4l2 ing are secured together by a plurality of longitudinally exl,682,037 8/1928 Craig ..239/4l5 X tending fastening means to eliminate the need for distortion prone tools.

9 Claims, 11 Drawing Figures c- & 4 (5765 7 6 so gee I I I PATENTEDJUH 6 [972 3,667", 682

INVENTOR. JOHN M. PURNELL Attorneys SPRAY GUN BACKGROUND OF THE INVENTION This invention relates to a spray gun for spraying atomized fluent materials.

In spray guns of the general type here under consideration, the gun housing generally comprises parts which are threaded together upon assembly. Such assembly invariably requires the use of wrenches which frequently results in distortion of the parts. Any such distortion may affect the proper working of the gun, could give rise to early malfunction, and makes replacement of parts a difficult matter.

Then, too, in the operation of such guns, the repetitive impacts between the orifice containing member and the orifice closure member to control material flow from the spray gun results in relatively rapid wear in either or both of such parts. In spray guns where adjustability between the impacting parts is provided for to compensate for wear therebetween, the adjustments throttle the air for atomization to sometimes limit the possible adjustments. Where there is no provision for adjustability between the impacting parts, the rapid wear requires frequent replacement of the parts at considerable expense and downtime.

It is generally an object of this invention to provide a spray gun in which distortion prone assembly methods and their attendant difficulties are eliminated and wherein adjustability is provided for between the orifice containing member and the orifice closure member of the gun without substantially affecting the flow volume of the atomizing air through the gun.

SUMMARY OF THE INVENTION According to the invention, a gun for spraying atomized fluent materials includes a housing wherein the main body and the adjacent enclosure parts are abutted, being flanged if necessary, and secured together with a plurality of fastening elements to thereby eliminate the need for distortion prone tools. The housing generally includes a discharge orifice for the fluent materials and atomizing air vent means associated with the orifice to provide for atomizing of the materials upon discharge from the orifice. Means are provided for supplying fluent materials and air to the housing. A movable member is reciprocally disposed in the housing. A reciprocating orifice closure means is disposed in the housing to control the flow of materials through the orifice with said closure means extending rearwardly beyond the movable member. Means are respectively provided for yieldably retaining the closure means in a position to close the orifice and the movable member in a position to close the passage means for the atomizing air. Means are further provided for driving the movable member rearwardly against its yieldable retaining means with the movable member initially moving relative to the orifice closure means to open the passage means and provide for the venting of atomizing air prior to material flow through the orifice and thereafter engaging with the orifice closure means to drive the closure means rearwardly and thereby open the orifice to provide for the flow of fluent materials. Upon removal of the force of the drive means, the respective yieldable retaining means are adapted to return the orifice closure means and movable member in a sequence to provide for closure of the orifice prior to closure of the atomizing air passage means. The structural arrangement of the spray gun provides for adjustability between the orifice containing member of the housing and the closure member of the orifice closure means to compensate for wear therebetween, with such adjustability not materially affecting the flow volume of atomizing air through the spray gun.

DESCRIPTION OF THE DRAWING FIGURES The drawings furnished herewith illustrate the best mode presently contemplated and set forth hereinafter for carrying out the invention.

In the drawings:

FIG. 1 is in part diagrammatic and in part perspective showing the spray gun of this invention;

FIG. 2 is a vertical section generally through the central axis of the spray gun of this invention and shows the elements in their inoperative position;

FIG. 3 is a front end elevation of the spray gun of this invention;

FIG. 4 is a rear end elevation of the spray gun;

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

FIG. 6 is a sectional view taken generally on line 6-6 of FIG. 2;

FIG. 7 is an enlarged sectional view taken generally on line 7-7 of FIG. 2;

FIG. 8 is a sectional view generally similar to that of FIG. 2 and shows the elements of the spray gun in position to provide for the flow of atomizing air from the gun prior to material flow;

FIG. 9 is a sectional view generally similar to that of FIGS. 2 and 8 and shows the elements of the spray gun in the operative position;

FIG. 10 is a partial vertical section of the spray gun of this invention and shows the elements of the gun disposed to provide a different mode of operation; and

FIG. 11 is a partial vertical section of the spray gun with the elements of the gun disposed to provide a still further different mode of operation.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Referring to the drawings, the spray gun is adaptable for use with fluent or semi-fluent material including by way of example, paint, foodstuffs, dyes, resins and oils. While the spray gun is intended for machine mounting and automatic operation, many of its features have application to a hand or non-automatic type gun.

The spray gun generally comprises a housing 1 adapted to receive material from a source 2 for discharge in the form of a spray or mist. The housing 1 generally includes an elongated body 3 which mounts a discharge head 4 forwardly and is provided with a longitudinally extending bore 5 which opens rearwardly and is closed by an end cap 6. Operation of the spray gun is generally controlled by a movable member 7 reciprocally disposed in the bore 5 of the body 3.

The material for spraying is forced under pressure through the material line 8 which communicates with the angular passage 9 in the head 4 of the gun and the volume of material may be controlled by a regulator valve 10 disposed in the line. The material exudes from the spray gun through an orifice 11 in the fluid tip fitting l2 threadedly engaged through the opening 13 from passage 9 generally centrally at the front of the head 4. The tapered end 14 of a reciprocating needle member 15 is engageable within the rear end of the orifice 11 to provide an on-otf control for the material flow through the orifice.

The hexagonal rear flange portion 16 of head 4 has a generally flat rear face 17 from which a cylindrical projection 18 extends rearwardly generally centrally thereof. The rear face 17 generally complements the adjacent face 19 of the flange portion 20 of body 3 with the projection 18 extending through the flange opening 21 and into the external recess 22. A plurality of circumferentially spaced threaded members 23 secure the

flange portions

16 and 20 together to'mount the head 4 on the body 3. The body 3 may be similarly shaped as the hexagonal flange 16 with the longitudinally extending edges being rounded generally as shown.

The longitudinally extending bore 5 in the body 3 is generally longitudinally aligned with the orifice 11 of the fluid tip fitting 12. The bore 5 is stepped intermediate its length forming a rearwardly facing shoulder 24 between the forwardly disposed smaller bore portion 25 and the rearwardly disposed larger bore portion 26. The larger bore portion 26 opens rearwardly of the body 3 and is closed by the end cap 6. End cap 6 includes a circumferential flange 27 which is engageable with the rear end of the body 3 and a plurality of circumferentially spaced threaded members 23 secure the end cap to the body.

The movable member 7 is reciprocally disposed in the stepped bore with the larger bore portion 26 serving as a cylinder for a piston or plunger 28. A valve carrier 29 slidable in the smaller bore portion is carried by the plunger 28 and extends forwardly therefrom. A valve 30 is disposed at the forward end of the smaller bore portion 25 between the bore portion 25 and an adjacent radially extending passage 31 for controlling atomizing air as will be explained hereinafter. The valve 30 includes a movable valve member 32 carried at the forward end of the carrier 29 and a rearwardly facing valve seat 33 engageable by the valve member 32 to close the valve. Closure of the valve 30 is effected by the biasing pressure of the coil spring 34 disposed in the bore portion 26 between the plunger 28 and the end cap 6 with closure being effected with the plunger remaining in spaced relation from the shoulder 34 intermediate the

bore portions

25 and 26.

The needle member 15 is reciprocally disposed generally along the longitudinal center line of the gun extending rearwardly from the longitudinal portion of head passage 9 through the bore 35 in the head 4 and its projection 18 and through the external recess 22. From the recess 22, the needle member 15 reenters the body through the stepped bore 36 longitudinally aligned with the valve seat 33 and passes through the radial passage 31. Beyond passage 31, the needle member 15 extends through the stepped bore 37 in the valve carrier 29 and enters the bore 38 of the reciprocal needle carrier 39 with the end of the needle member being secured in the extension member 40 threadedly engaged within the rear end of the carrier bore 37.

The needle carrier 39 comprises a stepped cylindrical member having a forward portion 41 of reduced diameter slidably disposed in the larger rear bore portion 42 of stepped bore 37 in the valve carrier 29. The enlarged rear portion 43 of carrier 39 is slidably disposed within the adjusting screw 44 which extends through and is threadedly engaged within the threaded bore 45 in the end cap 6. As shown in FIG. 2, the needle carrier 39 is biased forwardly to place the needle member 15 in position to close the fluid tip orifice 11 by the coil spring 46 disposed between the forward end of the adjusting screw 44 and the washer 47 on the carrier 39 adjacent to the shoulder 48 between the stepped

portions

41 and 43 of the carrier. A vent opening 49 maintains atmospheric pressure in the chamber of

springs

34 and 46 provided in the body bore portion 26 behind the plunger 28.

To prevent leakage of material from the passage 9 through the head bore 35 along the needle member 15 into the recess 22, the rear end of the head projection 18 is provided with a conical depression 50 around the needle member for receipt of a complementary packing washer 51 which is secured in place by a female packing nut 52 threadedly engaged on the projection. On the opposite side of the recess 22, a packing Washer 53 is seated in the stepped bore 36 around the needle member 15 and is secured by the male packing nut 54 threaded into the bore to prevent escape of air along the needle member from the passage 31. A bellows structure 55 may connect the opposed packing

nuts

52 and 54 in the recess 22 to keep the otherwise exposed portion of needle member 15 clean. Appropriate seals are used throughout the gun to properly contain the material and air in their respective passageways.

Referring particularly to the structure of FIGS. 1 through 9, air for operating the piston or plunger 28 is received from a source 56 which may represent an accumulator tank as supplied by a compressor. The air at a given line pressure is conducted from the source 56 through the line 57 to the body inlet passage 58 in communication with the chamber in the bore 26 ahead of the plunger 28. A valve 59, which may be solenoid operated, is disposed in line 57 and has an open position wherein air at line pressure is adapted to pass through the valve to actuate the plunger 28. In a second position of valve 59, the line 57 from the source 56 is closed and the air ahead of the plunger 28 is exhausted through the outlet line making it possible for the spring 34 to return the plunger 28 to its initial position. The valve 59 may be controlled by a conveyor or other means, not shown, related to the advance of successive workpieces, not shown.

The atomizing air for the spray gun is bled from the pressure line 57 through the line 61 which communicates with the inlet passage 62. A regulator valve 63 is disposed in the line 61 to control the pressure of the atomizing air as desired.

The air introduced at passage 62 flows through the body bore portion 25 to the passage 31 when the valve member 32 is lifted from its seat 33 by actuation of the plunger 28. The air is then conducted to the head 4 of the gun from passage 31 through the longitudinal body passage 64 which communicates with the generally

parallel head passages

65 and 66. From head passage 65, the air flows into the generally annular passage 67 in the air cap 68 for distribution to the parallel passages 69 from which the air is vented through the opposed apertures 70. A threaded member 71 extends through a tapped hole 72 in the head 4 and is adapted to intercept the head passage 65. The member 71 may be variously engaged within the hole 72 to serve as a metering valve for the passage 65 and so control the volume of air through the passage for venting from the apertures 70. A lock nut 73 secures the threaded member 71 in the desired position of adjustment.

From head passage 66, the atomizing air enters the annular passage 74 in the air cap 68 and is then conducted forwardly through parallel passages 75 to a second annular passage 76. From the passage 76 the atomizing air is vented through the annular clearance apertures 77 between the fluid tip 12 and the air cap 68 and the groups of

apertures

78 and 79. As best shown in FIG. 3, the apertures 78 are generally symmetrically disposed relative to the fluid tip orifice 11 and in a common plane through the apertures 70 and the orifice 11 while the apertures 79 are disposed in a plane normal thereto and symmetrical relative to the orifice 11. The air vented through the

apertures

70, 77, 78 and 79 are in large measure determinative of the speed, particle size and distribution pattern of the material issuing from the fluid tip orifice 11.

A selection of fluid tips 12 may be made available to provide orifices 11 of varying size, the selection being in accordance with the viscosity of the material and the quantity flow desired through the orifice. A selection of air caps 68 may similarly be made available in which one or more of the apertures are provided in varying size to provide for the desired spray characteristics. Since the air cap 68 is secured in place by a flanged annular air cap retainer 80 threaded handtight onto the forwardly projecting portion of the head 4 adapted to receive the retainer, a change in fluid tip 12 and/or air cap when desired is made with relative ease.

In the fabrication of the spray gun of this invention, the radially extending air passage 31 may be formed by a drilling operation from outside of the body 3 leaving a bore opening 81 from the body. As shown in the drawings, the opening 81 outwardly from the longitudinal passage 64 may be threaded and plugged by bracket means 82 for mounting the gun in the operating position.

In the operation of the spray gun of FIGS. 1-9, and with the material and air from the respective sources 2 and 56 in the ready, actuation of the valve 59 in the main air line 57 to the open position admits air through the inlet passage 58 into the bore chamber ahead of the piston or plunger 28. The air forces the plunger 28 along with the valve carrier 29 rearwardly against the biasing pressure of the plunger spring 34, As the plunger 28 along with the valve carrier 29 initially move rearwardly relative to the needle member 15, the valve member 32 is lifted from its seat 33 allowing the atomizing air from line 61 to flow through the valve 30 into passage 31 and forwardly through the described passages in the body 3, head 4 and end cap 68 for venting even while the tapered end 14 of the needle member 15 remains in closure contact with the orifice 1 1 in the fluid tip 12. As the movable member 7 continues rearwardly, engagement is made with the shoulder 48 of the needle carrier 39 as generally shown in FIG. 8. Thereafter the movable member 7 carries the needle carrier 39 along with the needle member 15 rearwardly to open the orifice 1 1 in the fluid tip 12 allowing the material to pass through the orifice and be acted upon by the atomizing air to provide the desired spray characteristics. In FIG. 9, the movable member 7 and needle member 15 are generally shown in the rearmost position wherein the needle carrier spring 46 is substantially fully compressed to arrest the rearward travel of the movable member.

At the conclusion of the spraying cycle, the valve 59 is actuated to close the air line 57 and place the bore chamber ahead of the plunger 28 in communication with the exhaust outlet 60. As the air is exhausted from ahead of the plunger 28, the

springs

34 and 46 bias the movable member 7 and needle carrier 39 forwardly on the return stroke. It is contemplated that the movable member 7 and needle carrier 39 will move together on their return stroke so that the tapered end 14 of the needle member 15 will seat to close the fluid tip orifice 11 even while the valve member 32 remains momentarily off from its seat 33 to provide for continued venting of atomizing air tending to clean the orifice 11 after its closure. The forward travel of the movable member 7 is arrested as the valve member 32 on the carrier 29 engages with the valve seat 33 to stop the flow of atomizing air and the gun is then in the ready for the next cycle of operation.

The repetitive contact at considerable force between the needle member 15 and the fluid tip 12 gives rise to relatively rapid wear therebetween such that material leakage through the orifice 11 results. Periodically the fluid tip 12 and/or the needle member 15 must be replaced resulting in downtime. However, adjustment of the needle member 15 relative to the fluid tip 12 is provided for to greatly increase the wear life of those members and thereby minimize the downtime for replacement.

If material leakage past the needle member 15 when seated in the orifice 11 is detected, adjustment affecting the needle member is indicated and can be effected as follows. The lock washer 83 securing the needle member extension 40 relative to the needle member carrier 39 is loosened so that it becomes possible to thread the needle member extension forwardly further into the needle member carrier bore 38. As a consequence the needle carrier 39 and its washer abutment 47 are driven rearwardly relative to the adjustment screw 44 to further compress the needle carrier spring 46 and thereby better seat the needle member 15 in the fluid tip orifice 11. After the desired adjustment is effected, the lock washer 83 is resecured to again lock the needle member 15 in the adjusted position.

Adjustment affecting the needle member 15 is alternatively effected by initially loosening the lock washer 84 securing the adjusting screw 44 relative to the end cap 6 making it possible to thread the adjusting screw forwardly further into the end cap which also results in a further compression of the needle carrier spring 46 to better seat the needle member 15 in the fluid tip orifice 11. The lock washer 84 must be resecured after the desired adjustment is effected.

As the needle member 15 and/or fluid tip 12 exhibit the effects of wear, the distance between the movable member 7 and the needle carrier shoulder 48 is generally shortened. The mode of adjustment affecting the needle member 15, wherein the extension member 40 is threaded further into the needle carrier 39, affords the advantage of tending to restore the original distance between the movable member 7 and shoulder 48 so that the operation of the valve 30 and the venting of atomizing air through the air cap 68 in timed relation to the operation of the needle member and the flow of material through the orifice 1 1 is little disturbed. However, the amount of wear to be tolerated between the needle member 15 and/or the fluid tip 12 prior to their replacement is not so great that a shortened distance between the movable member 7 and shoulder 48 resulting from inward adjustments of the adjusting screw 44 will adversely affect the desired timed flow relation between the atomizing air and the material. With either mode of adjustment the flow volume of atomizing air through the valve 30 is substantially unafiected.

Replacement of the needle member 15 in the spray gun is also accomplished with relative ease. To effect a replacement of the needle member, the extension member 40 is unthreaded rearwardly from the needle carrier 39 and the needle member is withdrawn through the carrier bore 38. A new needle member 15 is then press fit into the extension member 40 and the needle member and its extension are reassembled into the gun. Thus, for needle member and/or fluid tip replacements, a major dismantling of the gun is unnecessary and the period of downtime for the gun can be relatively short.

The spray gun of FIG. 10 is generally similar to the gun of FIGS. l-9 but shows a somewhat different mode of operation wherein the valve has replaced the valve 59 in the air line 57. The atomizing air for the gun of FIG. 10 is derived in a manner to be described hereinafter and does not entail use of a bleed line 61 as appears with the gun as shown in FIGS. 1-9. As a consequence the inlet passage 62 for the spray gun of FIG. 10 is simply closed by a threaded plug 86.

The spray guns of FIGS. 1-9 and FIG. 10 are provided with a longitudinal passage 87 in the body 3 which places the portion of bore 26 ahead of the plunger 28 in communication with the body passage 64 and may be an extension of the passage 64 as generally shown in the drawings. A threaded member 88 extends through a tapped hole 89 in the body 3 and is adapted to intercept the passage 87 and may be .variously engaged to serve as a metering valve and so control the volume of air through the passage. A lock nut is provided to secure the threaded member 88 relative to the body 3. In the gun of FIGS. 1-9 the passage 87 is not being used and therefore the threaded valve member 88 is engaged to close the passage.

The valve 85 disposed in the air line 57 of the gun in FIG. 10 is a two-position, on-otf valve which may be solenoid actuated. When the valve 85 is opened, air at line pressure is admitted through the inlet passage 58 into the bore chamber ahead of the plunger 28 of the movable member 7 to actuate the movable member rearwardly similarly as in the gun of FIGS. 1-9. In the gun of FIG. 10, however, a portion of the air admitted into the bore chamber ahead of the plunger 28 is diverted through passage 87 for use as atomizing air. From passage 87, the atomizing air continues to flow through body passage 64 and the

head passages

65 and 66 for venting in a manner similar to the gun of FIGS. l-9. The threaded valve member 88 is set to meter the volume of atomizing air through passage 87 as desired. I

Since the passage 87 of the spray gun of FIG. 10 remains open, diversion of atomizing air takes place as soon as valve 85 is opened to assure that such air is being vented through the air cap 68 prior to the commencement of material flow through the fluid tip orifice 11. Upon closure of valve 85 at the end of the spray cycle, all of the air in the bore chamber ahead of the plunger 28 is exhausted forwardly through the air cap passages. The exhaust venting of air through the air cap 68 will continue at least momentarily after the needle member 15 is reseated in the orifice 11 which will tend to clean the orifice after its closure.

The spray gun of FIG. 1 l is generally like the guns of FIGS. 1-9 and FIG. 10, but is adapted for hydraulic atomization in which case there is no need for atomizing air. There being no need for atomizing air, the inlet passage 62 is closed by a threaded plug 86 and the valve member 88 is threadedly engaged to close the passage 87. For hydraulic atomization the pressure relied upon at the material source 2 may be higher than when using air atomization. The air for actuating the plunger 28 of movable member 7, and hence the needle member 15, is supplied through the line 57 which is controlled by the valve 59 therein. At the conclusion of the spray cycle for the gun of FIG. 11, the valve 59 is adapted to close the air line 57 from the source 56 and to exhaust the air from the bore chamber ahead of the plunger 28 through the exhaust outlet 60.

As herein described the spray gun of this invention is versatilely adapted for several modes of operation. The gun further provides for adjustment to compensate for wear between the needle member and fluid tip to substantially increase the wear life of those parts and decrease downtime for their replacement. Such adjustment can be made without adversely affecting the flow of atomizing air through the gun. When replacement of the needle member and/or fluid tip ultimately does become necessary for the spray gun of this invention, such can be effected with relative ease as a major dismantling of the gun is not necessary. The flange securement between the body and adjacent head and rear cap, respectively, precludes the need for wrench type tools which might cause a distortion of the cylinder bores for the movable member and other reciprocating parts to adversely affect the useful life and operation of the spray gun.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. In a gun for spraying atomized fluent materials, a housing having a discharge orifice for the fluent materials, means for supplying the fluent materials to the housing, said housing having a bore longitudinally aligned with said discharge orifice, a movable member reciprocally disposed in the housing bore, an orifice closure member in said housing and extending rearwardly through said movable member, a carrier for the orifice closure member disposed rearwardly of said movable member, said carrier having a longitudinally extending through bore for receiving the orifice closure member, means for movably securing the orifice closure member within the bore of said carrier, means biasing the carrier for the closure member forwardly to place said closure member in a position of closure over the orifice, and means for driving the movable member rearwardly within the housing bore, said movable member being initially movable relative to the orifice closure member and thereafter engaging its carrier to move the same along with the closure member rearwardly against the force of said biasing means to open the orifice and provide for the flow discharge of materials from the orifice said orifice closure member being selectively movable relative to the carrier to effect adjustment between the carrier and movable member, and said closure member being removable rearwardly from the bore of the carrier for replacement.

2. The invention as set forth in claim 1, wherein the housing comprises a longitudinally extending body mounting an orifice containing head at the forward end thereof and an end cap at the rear thereof, said head and end cap each having flange portions complementing the corresponding end of the housing body, and a plurality of longitudinally extending fastening means securing the head and end cap to the body.

3. The invention as set forth in claim 1, wherein the discharge orifice is disposed in an orifice containing member secured relative to the housing and the means biasing the carrier for the orifice closure member forwardly comprises a spring, and means to increase the biasing force of said spring to compensate for wear between said orifice containing member and the orifice closure member.

4. The invention as set forth in claim 3 wherein the means for movably securing the orifice closure member within the bore of said carrier is a threaded connection providing for relative movement therebetween to increase the biasing force of said spring.

5. The invention as set forth in claim 3 wherein an adjusting screw is threadedly engaged with the housing and the carrier for the orifice closure member is slidably disposed within a through bore in the adjusting screw, and wherein the spring for biasing the carrier for the orifice closure member is disposed between the adjusting screw and the carrier, said adjusting screw being selectively movable relative to the housing and carrier to increase the biasing force of said spring.

6. In a gun for spraying atomized fluent materials, a housing having a discharge orifice for the fluent materials and atomizing air vent means associated with the orifice to provide for atomrzmg of the materials upon discharge from the orifice,

means for supplying the fluent materials to the housing, said housing having a stepped bore longitudinally aligned with said discharge orifice with the smaller bore portion disposed forwardly of the larger bore portion, a stepped plunger unit reciprocally disposed in the stepped housing bore, an orifice rearwardly to open the orifice and provide for materials flow through the orifice, said orifice closure member being selectively movable relative to the carrier to effect adjustment between the carrier and plunger unit, and said closure member being removable rearwardly from the bore of the carrier for replacement.

7. The invention as set forth in claim 6, wherein the discharge orifice is disposed in an orifice containing member secured relative to the housing and the means biasing the carrier for the orifice closure member forwardly comprises a spring, and means to increase the biasing force of said spring to compensate for wear between said orifice containing member and the orifice closure member.

8. The invention as set forth in claim 7, wherein the means for movably securing the orifice closure member within the bore of said carrier is a threaded connection providing for relative movement therebetween to increase the biasing force of said spring.

9. The invention as set forth in claim 7 wherein an adjusting screw is threadedly engaged with the housing and the carrier for the orifice closure member is slidably disposed within a through bore in the adjusting screw, and wherein the spring for biasing the carrier for the orifice closure member is disposed between the adjusting screw and the carrier, said ad justing screw being selectively movable relative to the housing and carrier to increase the biasing force of said spring.

STATES 'fFiC'lZ i on Q r mp s n m mi .lhli $1 Patent No. 3 66 ,682 Dated June 6 2 1972 Inventor(s) John ivh Purnell It is certified that error appears in. the above-identified patent and that: said Letters Patent are hereby corrected as shown below:

Column 8, Line 26, after "orifice" insert closure member reciprocally disposed in said housing and extending rearwardly through said plunger unit, a carrier for the orifice closure member disposed rearwardly of said plunger unit, said carrier having a longitudinally extending through bore for receiving the orifice closure member, means for movably securing the orifice closure member within the bore of said carrier, means biasing the carrier for the orifice closure member forwardly to place said closure member in a position of closure over the orifice, valve means in the smaller bore portion of said housing and including a valve closure member carried at the forward end of the plunger unit, means biasing the plunger unit forwardly placing the valve member in position to close the valve means first means for supplying air to the housing and communicating with the larger bore portion ahead of the enlarged portion of the plunger unit to drive said unit rearwardly against the pressure of the corresponding biasing means, second means for supplying air to the housing and communicating with the smaller bore portion behind said valve means, and passage means in said housing connecting the smaller bore portion behind.

said valve means with the atomizing air vent means said plunger unit initially moving rearwardly relative to the orifice closure member under the influence of air from the first air supply means to open the valve means and provide for the venting of atomizing air from thesecond ir supply means prior to materials flow through the orifice and said elunger unit thereafter engaging said carrier and moving said carrier and orifice closure member Signed sealed this 12th day of December 197? Attestt;

EDWARD MQFLETCEERDJRQ Attesting Officer ROBERT oorrscHALK Commissioner of Patents

Claims

6. In a gun for spraying atomized fluent materials, a housing having a discharge orifice for the fluent materials and atomizing air vent means associated with the orifice to provide for atomizing of the materials upon discharge from the orifice, means for supplying the fluent materials to the housing, said housing having a stepped bore longitudinally aligned with said discharge orifice with the smaller bore portion disposed forwardly of the larger bore portion, a stepped plunger unit reciprocally disposed in the stepped housing bore, an orifice rearwardly to open the orifice and provide for materials flow through the orifice, said orifice closure member being selectively movable relative to the carrier to effect adjustment between the carrier and plunger unit, and said closure member being removable rearwardly from the bore of the carrier for replacement.

9. The invention as set forth in claim 7 wherein an adjusting screw is threadedly engaged with the housing and the carrIer for the orifice closure member is slidably disposed within a through bore in the adjusting screw, and wherein the spring for biasing the carrier for the orifice closure member is disposed between the adjusting screw and the carrier, said adjusting screw being selectively movable relative to the housing and carrier to increase the biasing force of said spring.