US3219276A - Plural nozzles having intersecting spray and control therefor - Google Patents

Description

Nov. 23, 1965 E. o. NORRIS 3,219,276

PLURAL NOZZLES HAVING INTERSECTING SPRAY AND CONTROL THEREFOR Filed Oct. 16, 1962 5 Sheets-Sheet 1 INVENTOR ATTORNEY Nov. 23, 1965 E. o. NORRIS 3,219,276

PLURAL NOZZLES HAVING INTERSECTING SPRAY AND CONTROL THEREFOR Filed Oct. 16, 1962 5 Sheets-Sheet 2 INVENTOR EDWARD 0. NOR/{V5 ATTORNEY Nov. 23, 1965 E. o. NORRIS 3,219,276

PLURAL NOZZLES HAVING INTERSECTING SPRAY AND CONTROL THEREFOR Filed Oct. 16, 1962 5 Sheets-Sheet 3 70 /07 I/O /08 l //8 9/ 29 7 72 74 7e II A ' INVENTOR 0 WA E0 0. NOR/9A5 7 #0 ATTORNEY Nov. 23, 1965 E. o. NORRIS 3,219,276

PLURAL NOZZLES HAVING INTERSECTING SPRAY AND CONTROL THEREFOR Filed Oct. 16, 1962 5 Sheets-Sheet 4 yo Qf//.

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ATTORNEY E. O. NORRIS Nov. 23, 1965 5 Sheets-Sheet 5 Filed Oct. 16, 1962 ATTORNfY United States Patent 3,219,276 PLURAL NOZZLES HAVING INTERSECTING SPRAY AND CONTROL THEREFOR Edward 0. Norris, Ledgemoor Lane, Westport, Conn. Filed Oct. 16, 1962, Ser. No. 230,867 6 Claims. (Cl. 239186) This invention relates to spraying devices and more particularly to two fluid type material atomizers.

An object of this invention is to provide a two fluid or air gun type atomizer with a maximum utilization of the atomizing gas energy.

Another object is to provide such an atomizer wherein the material being atomized may be simultaneously exposed to the corona of an electrostatic field.

A further object is to provide such an atomizer which produces uniformly sized and uniformly charged spray particles.

Another object is to provide such an atomizer which atomizes commercial volumes of materials to suitable particle sizes with ultra low air pressures and volumes.

A further object is to provide such an atomizer having means to controllably reduce the intial velocity of the atomized particles.

Another object is to provide such an atomizer which creates a fan-shaped spray Where the spray fan may be rapidly oscillated Without physical movement of the atomizer.

A further object is to provide a spray coating system with several spray heads having oscillating fans whose oscillation may be readily correlated.

Another object is to provide such an atomizer which may be precisely controlled for skip-spray operations.

A further object is to provide such an atomizer where the material to be atomized, exudes through an adjustable peripheral slot having remote means for momentarily increasing the slot opening to release any clogging particles.

Another object is to provide a system of the above type having a reciprocating spray head connected to a source of high tension electric potential wherein the head is electrically insulated from all control devices.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

In accordance with this invention each air gun comprises a pair of nozzles having concentric passages for air and spray material discharging at a tip through concentric orifices to provide a cone of atomized spray. The two nozzles are mounted with their axes intersecting so that the sprays therefrom converge to form a fan-shaped spray pattern. This pattern is oscillated angularly by varying the air pressure to the respective nozzles. Also the guns may be mounted on a slide which is reciprocated vertically or horizontally so as to sweep the surface of the articles to be sprayed. The invention provides pressure control valves which are mounted to reciprocate vertically with the heads for controlling the pressure of the spray material as it is fed to the nozzles. Cam actuated valve means is provided for alternately varying the air pressure to the respective nozzles of each head for oscillating the spray pattern. Each nozzle includes a bellows actuated valve for the spray material passage. A remote controlled valve is adapted to control the supply of air to the various bellows and to the various nozzles for shutting off the jets of spray material and simultaneously interrupting the supply of atomizing air. A bleeder valve supplies bleeder air to the nozzles when the jets are shut ofl so as to prevent the spray material from clogging the nozzles. Remote control means is also provided for varying the material feed pressure during the operation of the heads.

The nature of the invention will be better understood from the following description, taken in connection with 3,219,276 Patented Nov. 23, 1965 "ice the accompanying drawings in which a specific embodiment has been set forth for purposes of illustration.

In the drawings:

FIG. 1 is a vertical section through the spraying apparatus with parts in elevation;

FIG. 2 is a detail view on a larger scale of the valves for controlling the spray angle together with their operating mechanism;

FIG. 3 is a detail view on a still larger scale of the support for the spray gun with parts in section for clarity;

FIG. 4 is a transverse section taken on theline 44 of FIG. 3 but on a larger scale;

FIG. 5 is an axial section through a spray nozzle on an enlarged scale;

FIG. 6 is a detail view of the flanged sleeve for ad justing the needle valves;

FIG. 7 is a detail view of a coated nozzle tip;

FIG. 8 is a fragmentary view of a nozzle tip showing the bleeder hole;

FIG. 9 is a vertical section taken on line 9-9 of FIG. 10 showing the mechanism for adjusting the relative angles of the nozzles;

FIG. 10 is a curved section taken on the line 1010 of FIG. 9;

FIG. 11 is a partial axial section similar to FIG. 5 illustrating a modified nozzle construction;

FIG. 12 is a vertical section through one of the remote controlled valves for regulating the material feed;

FIG. 13 is an enlarged sectional detail of the nozzle of FIG. 5; and

FIG. 14 is a schematic diagram of the control system for the spray mechanism.

Referring to the drawings more in detail the invention is shown as embodied in a paint spray apparatus comprising amovable platform 10 carrying a vertical cabinet 11 having arear wall 12 andside walls 13. Therear wall 12 is provided withvertical channels 14 forming tracks on which slide 15 reciprocates. An actuatingcylinder 16 mounted on theplatform 10 carries a reciprocating piston having arod 17 connected by abracket 18 to theslide 15 for causing vertical reciprocating of the slide.

Theslide 15 carries a pair ofspray gun brackets 20 to each of which a cylindricalspray gun housing 21 is adjustably attached bycoupling members 22. Eachcoupling member 22 has anupper part 22a which is slidably mounted for horizontal adjustment on thegun bracket 20 and is secured by aset screw 23. Thecylindrical housing 21 is horizontally adjustable in the lower part 22b of themember 22 and is secured by aclamping bolt 24. The lower part 22b of thecoupling member 22 is pivotal- 1y connected to theupper part 22a by apin 25 and is secured in adjusted position by anut 26.

Eachcylindrical housing 21 carries abracket 27 having divergingarms 28 on whichspray nozzles 29 are secured.

Thebrackets 20 and thecylindrical housings 21 are made of insulating material. Thebracket 27 is of metal and is connected by aline 30 to aterminal block 31 mounted on abracket 32 secured to theslide 15 and supplied with a high electrical potential by aflexible lead line 33. Acontrol box 34 for controlling the spray is mounted on aside wall 13. Abracket 36 carries a pair of remote controlledmaterial feed valves 37 to be described.

Articles 44 to be sprayed are suspended on a travelingconveyor 45 which is supported by a suitable frame not shown.

In operation theslide 15 is reciprocated vertically as the articles are fed past thespray nozzles 29 so as to coat the exterior surfaces of the articles uniformly in a manner well known in the art. Suitable controls to be described are provided for regulating the spray and for shutting off the spray when the heads pass the surfaces to be coated. The structure of the spray nozzles and the control system of this invention are more fully set forth below.

FIG. 2 illustrates the construction of the valve mechanism for controlling the spray-fan oscillation. This mechanism comprises a base carrying pairs ofblocks 51 in which adjusting screws 52 are journalled.Valve housings 53 are carried byblocks 54 which are threaded onto the adjusting screws 52 for lateral adjustment of the valves. Eachvalve housing 53 includes a valve chamber connected to an inlet pipe 55 and adapted to establish communication with an outlet pipe 56 when the valve is actuated or to break such connection when the valve is in closed position. Each valve is actuated by aplunger 57 carrying at its end aroller 58 which engages and is actuated by a pivoted arm 59. The arms 59 carrycam rollers 60 engaging opposite sides of atriangular cam 61 which is mounted on a shaft 62 driven through a reduction gear inbox 63 from anair motor 64. The arrangement is such that the two valves are alternately actuated to supply air under pressure to the outlet lines 56 as the cam is driven by themotor 64.

Eachspray nozzle 29 comprises a fixed housing having at its forward end a bore 71 defining anair chamber 72 and terminating forwardly in ashoulder 73. Anair sleeve 74 is disposed within the bore 71 and defines the inner wall of theair chamber 72. Theair sleeve 74 carries at its forward end a sealingflange 75 which fits tightly within the bore 71 against theshoulder 73 to close the forward end of theair chamber 72. Thesleeve 74 carries centeringribs 76 which seat within the bore 71 and projects rearwardly from thehousing 70, the rearward extension carrying centeringribs 77 forming a continuation of theribs 76. Acap 78 is disposed over theribs 77 and is held in place by a clampingnut 79 engaging ashoulder 80 on thecap 78 and threaded onto thehousing 70. Air is supplied to theair chamber 72 through anair passage 81 in thehousing 70 and flows between theribs 76 and 77 within the annulus between theair sleeve 74 and thecap 78 to anannular discharge orifice 82 defined by the end of thecap 78 and aflange 83 at the end of theair sleeve 74. The rearward end of the air passage within thecap 78 is tapered as shown at 84 to provide an increased air velocity at thedischarge orifice 82.

Forwardly of theshoulder 73 the housing is formed with a bore 88 defining the outer surface of amaterial chamber 89. Apaint sleeve 90 is disposed within the bore 88 to form the inner surface of thematerial chamber 89. The bore 88 terminates forwardly in a shoulder 91 against which ashoulder 92 of thesleeve 90 is clamped by a clampingnut 93. Thesleeve 90 extends through the bore 88 and into thesleeve 74 and carries at its rearwardend centering ribs 95 engaging the inner surface of the ,air sleeve 74. The housing is formed with apassage 97 for supplying material to be sprayed to thechamber 89.

Avalve stem 98 carrying at its rearward end avalve flange 99 slides axially within thesleeve 90. Thevalve flange 99 is of conical form and is adapted to seat against a conical valve seat 100 formed in the end of thesleeve 74, as shown in FIG. 13. The portion of thevalve stem 98 within thesleeve 90 is sealed against the spray material by apacking ring 101 which bears against the end of thesleeve 90 and engages a cup-shapedwasher 102 which is held by aspring 103 disposed around thestem 98 and bearing against ashoulder 104 on the stem.

Aflanged adjusting sleeve 107 is threaded into thehousing 70 by looselyfitting threads 108 which permit limited axial movement of thesleeve 107. Thesleeve 107 is biased forwardly by a spring 109 and is manually adjustable by a knurled flange 110 which is accessible throughopenings 111 in thehousing 70. A cross pin 112 at the forward end of thevalve stem 98 is adapted to slide axially inslots 113 formed in the adjustingsleeve 107. As shown in FIG. 5 these slots extend axially and permit the valve to be rotated for adjustment bysleeve 107.

In operation, this combination functions, in conjunction with the outwardly opening valve, which forms the material feed slot, to permit clearing the slot during operation, by remote control.

This is done by causing the nozzles to skip spray by momentarily releasing air pressure from the bellows to causespring 114 to close the valve and then again feeding compressed air to the bellows to cause the valve to open.

The fast rearward motion atdisc 119 forces the valve open until the disc is stopped by the end of theflanged adjusting sleeve 107. However, its momentum causessleeve 107 to momentarily move forward against the pressure of spring 109 due to the loosefitting threads 108. This causes thevalve 99 to momentarily move forward and thus increase the width of paint feed slot to permit any clogging particles to be ejected. The valve slot then returns to its normal opening.

In FIG. 6 the slots 113a are sown as slightly helical so as to cause a slight rotation of the valve stem for cleaning purposes to prevent the valve seat from becoming contaminated. The type of slot used will depend upon the nature of the material being sprayed.

Avalve spring 114 is disposed between acup 15 on thevalve stem 98 and the forward end of thesleeve 90.

The valve stem 98 is controlled by abellows 117 the forward end of which is secured to acap 118 which is threaded onto the forward end of thehousing 70. The rearward end of thebellows 117 carries adisc 119 which is adapted to engage the end of thevalve stem 98 for opening the valve when the bellows is extended. Thedisc 119 also engages the end of the adjustingsleeve 107 which forms a cushion stop to limit the opening of the valve. An adjustablehollow stop member 120 is disposed within thebellows 117 to bear against the inner surface of theend wall 119 to limit the contraction of the bellows. This stop member is adjusted to provide a small clearance with the end of the valve stem when the valve is in closed position.

In operation the spray material is supplied through thepassage 97 to thechamber 89 thence along the annular passage between thesleeves 74 and 90 to the annular orifice between thevalve flange 99 and the seat 100. This valve is normally closed by thespring 114 but is opened when air under pressure is supplied to thebellows 117.

Air under pressure for atomization of the spray material is supplied from theair passage 81 in thehousing 70 to theair chamber 72, thence along the annular passage between theair sleeve 74 and thecap 78 to the annular orifice at the end of thecap 78 where it commingles with the spray material to form a cone-shaped spray. It will be noted that the air orifice at the end of thecap 78 lies in substantially the same plane as the inner orifice through which the spray material is supplied. This construction reduces the tendency of spray material to be deposited on the outer surface of the cap.

FIG. 7 shows acap 78a similar to thecap 78 but with a coating ofan insulating and antiadherence material such as Teflon. This coating prevents spray particles from collecting on and adhering to the outer surface of the cap and also serves to concentrate the electric charge at the orifice end of the nozzle.

FIG. 8 illustrates a cap 78b having bleeder holes 126 which discharge air from theair chamber 72 against the under surface of a flange 127 on the clamping nut 79a. This flange is adapted to deflect the air rearwardly toward the nozzle tip so as to prevent collection of spray particles on the outer surface of the cap 78b. Either of these embodiments may be used in the nozzle construction of FIG. 5.

As illustrated in FIG. 3 thehousings 70 of a pair ofnozzles 29 are mounted on the divergingarms 28 of thebracket 27 in such position that the jets from the nozzles impinge on each other and form a flat, fan-shapedspray pattern 129 as shown in FIG 1.

As illustrated in FIG. 3 the material to be sprayed, such as paint, is supplied to the two nozzles bypipes 130 extending through thecylindrical housing 21 and to passages in the bracket which communicate with thematerial passages 97 in thehousings 70. Air under pressure for spraying is supplied throughpipes 131 which pass through thecylindrical housing 21 and thebracket 27 to communicate with theair passage 81 in thehousings 70. Control air for thebellows 117 is supplied by asingle pipe 132 which communicates with a passage 133 in thebracket 27. This passage 133 divides to com municate with a pair ofpipes 134 which communicate with the interiors of the respective bellows 117. Thepipes 130, 131, and 132 may be formed of flexible tubing of electrical insulating material such as nylon or a polyethylene material.

FIGS. 9 and illustrate an embodiment wherein the angle between the two nozzles is made adjustable. In this form bracket 27a corresponds to thebracket 27 of FIGS. 1 and 3. The bracket 27a terminates in a transverse,arcuate member 137, having a pair ofarcuate channels 138 in whicharcuate racks 139 and 14:9 slide. Each of these racks carries ahousing 70 of the type described, which housings are disposed on opposite sides of the axis of the bracket 27a. Apinion 141 journalled in the walls of themember 137 engagesteeth 142 and 143 on concave and convex arcuate surfaces respectively of the two racks so that the racks are actuated in opposite directions by thepinion 141. The pinion carries anactuat ing knob 144 and a lockingknob 145. The arrangement is such that upon rotation of the actuating knob the two racks are shifted in opposite directions so that the twonozzles 29 are spaced apart and angularly rotated from an inner position as shown in full lines in FIG. 9 to an outer position as shown in dotted lines, with a consequent increase in the relative angles of the jets. The shape of the fan ofspray 129 can thus be controlled as desired.

In the embodiment of FIG. 11 thenozzle 29a comprises ahousing 150 having anannual air chamber 151 formed by anouter wall 152 and an innerconcentric wall 153. Anouter cap 154 is attached to the rearward end of thewall 152 and an innerconcentric cap 155 is attached to theinner wall 153. Thecaps 154 and 155 are spaced to form a rearward continuation of theair annulus 151 terminating rearwardly in anannular air orifice 156. Thehousing 150 contains an air supply passage 157 opening into theair chamber 151. Theinner cap 155 is formed with aconical valve seat 160 against which aneedle valve 161 seats. Theneedle valve 161 has astem 162 mounted to slide in abore 163 in thehousing 150. Forwardly of thebore 163 the stern 162 carries ashoulder flange 164 which is pressed rearwardly by aspring 165 for closing the valve opening. Thespring 165 bears against acup 166 which contacts apacking ring 167 disposed in a packing gland closed by anut 168 threaded into thehousing 150. A passage 169 for the spray material communicates with theannulus 170 between the stern 162 and thewall 153 through which the spray material is fed to theneedle valve 161. Thestem 162 extends forwardly beyond thehousing 150 and carries at its forward end an adjustment nut 171 having a sphericalrear surface 172 against which a bifurcated arm 173 presses for opening the valve. The arm 173 is pivoted to thehousing 150 and at its other end carries an adjustingscrew 176 engaging the end of a bellows 177. The bellows is secured to an arm 28a attached to the bracket 27b. The bellows is supplied with air for expanding the bellows to open the needle valve bypipe 134.

In this embodiment the operation is similar to that of FIG. 5 except that the needle valve is shifted rearwardly to open position.

FIG. 12 illustrates a remote controlled valve of the type used for regulating the feed of spray material to the nozzles. This valve comprises ahousing 180 carrying adiaphragm 181 dividing thehousing 180 into anair chamber 182 and amaterial chamber 183. Ableeder hole 195 in thehousing 180 communicates with thechamber 182 to facilitate air release. Spray material enters through 201 and is supplied to thechamber 183 through anorifice 184 in thehousing 180 having avalve seat 185 adapted to be closed by avalve head 186 on astem 187 attached to thediaphragm 181 by clampingmembers 188 and pressed into closed position by aspring 189.

Spray material is discharged from thechamber 183 through anoutlet opening 190 connected to apipe 191. Air is supplied to thechamber 182 by apipe 192 through aport 193. The arrangement is such that an increased air pressure in thechamber 182 tends to open thevalve 186 to cause the pressure of the material in thechamber 183 to build up until the air pressure is balanced by the pressure of the material in the latter chamber. Hence the pressure of the material fed to the nozzles is varied by a corresponding variation in the air pressure supplied to theair chamber 182.

Referring to the system shown in FIG. 14 the material to be sprayed is fed from amaterial tank 200 under pressure through apipe 201 to a pair of remote controlledmaterial feed valves 37, the type of which is shown in FIG. 12. From thevalves 37 the material is supplied bypipes 191 to thematerial feed pipes 130 of FIG. 3 which feed the material to thenozzles 29 of each head.

Air under pressure is supplied from a supply line 205 throughfilter 206 to aT having branches 207 and 208.Branch 207 is connected through apressure regulator valve 209 to supply air to theair motor 64 which is connected to drivecam 61 of the sprayangle control valves 210 which are shown in detail in FIG. 2. Abranch line 207a supplies pressure to thematerial tank 200 through a pressure regulator (not shown). Thebranch 208 leads to a pressure regulator valve 211, the output pressure of which is controlled by acontrol knob 212. The outlet side of the valve 211 is connected by apipe 213 to aT having branches 214 and 215. Thebranch 214 connects tolines 214a leading to a pair ofpressure control valves 202 which are mounted on thecabinet 34. The output pressure of thevalves 202 which is controlled byknobs 202a is fed bylines 192 to the pressure regulating chamber of thematerial feed valves 37. Hence the pressure of the material fed to the nozzles can be controlled by suitable actuation of the knobs 202a while the nozzles are reciprocating.

Thebranch 215 connects to a remote control, solenoidoperated, three-way valve 216 having an outlet pipe 217. Thevalve 216 normally connects theinlet pipe 215 to the outlet pipe 217 but is adapted when energized toshutoff inlet pipe 215, and to vent the pipe 217 to the atmosphere.

From the line 217 air is supplied throughcheck valve 235 andline 222 to a pair of lowpressure regulator valves 223, the outputs of which are connected bylines 224 to theair supply pipes 131 of the various nozzles. From theline 222 air is supplied byline 225 to highpressure regulator valve 226 having anoutput line 227 connected bylines 228 to theangle control valves 210. The outlet sides ofangle control valves 210 are connected bylines 229 connected to the nozzle lines 131. From lines 217branch lines 230 lead to a pair ofneedle valves 231 the outlet sides of which are connected bylines 132 to thebellows 117 of the various nozzles. Aneedle valve 221 is con nected between theline 215 and theline 222 to supply bleed air to the nozzles when thesolenoid valve 216 is closed so as to prevent spray material from collecting on and clogging the nozzles.

In the operation of this system the spray is controlled by the solenoid operatedvalve 216 which may be actuated automatically by theslide 15 when the spray heads pass the upper or lower edges of the articles being sprayed.

They may also be actuated either automatically or manually to shut off the spray between articles. When thesolenoid valve 216 is opened air under pressure is supplied to thevarious bellows 117 to open thenozzle valves 99 in the material feed orifices. Air for atomization at a given low pressure is also supplied fromvalves 223 and 224 to the nozzles and air under a higher pressure is fed to the cam actuatedangle control valves 210 which supply pulses of such high pressure air to the respective nozzles for oscillating the spray pattern.

When thesolenoid valve 216 is closed the air supply to thebellows 117 is cut off and the bellows are vented to the atmosphere to close thenozzle valves 99. Atomizing air is also cut off except for the bleeder air through theneedle valve 221 which supplies suificient air to prevent the nozzles from clogging.

By mounting thematerial feed valves 37 on the slide any variation in pressure of the material due to a change in relative height is eliminated. This pressure can be readily adjusted by themanual knob 212 which varies the air pressure to thepressure chambers 182 of thevalves 37. The spray is instantly shut off without drip when thesolenoid valve 216 is closed and is instantly restored when this valve is again opened.

One major feature of this invention is the manner in which the initial air jet and spray particle velocities are retarded by the impingement of the converging spray jets.

Relatively slow, controlled velocity, highly charged, spray particles are of great importance to high efiiciency electrostatic coating operations.

One of the major reasons why electrostatic air spray (two fiuid type) operations have not been considered very efiicient in the past, has been due to a very considerable extent, to the relatively high air and particle velocities in the coating area.

The following particle velocity figures, determined by actual tests, will illustrate this feature.

The particle and air velocity measured at 11 inches from one of these nozzles, with p.s.i. of atomizing air pressure has been measured to be in the order of 1100 ft./min. When one of these dual nozzle sprayheads has the nozzle so mounted that their spray jets converge at an included angle of 101 degrees, the resultant air and particle velocities have been measured to be in the order of 630 ft./min. While this compares favorably with the measured air and particle velocity of 1100 f.p.m. at 11 inches from a standard low pressure air spray gun at 15 p.s.i. atomizing air pressure and also with the above described velocity of a single nozzle, it still compares unfavorably with the measured velocity at 11 inches from a rotating atomizing disc, of 250-350 f.p.m.

The effect of these relative velocities on the electrostatic deposition, attraction and wrap around was determined by actual coating tests, the high velocities resulting in definitely poorer efliciencies and coating results.

It has now been determined that when a pair of these nozzles are so associated that the spray jets converge at included angles in the order of 130 to 140 degrees, the resulting particle velocities are in the order of 130 to 170 f.p.m. This has been found to result in excellent deposition efiiciency. However, one factor limiting this type of convergence angle, is the necessity for avoiding the coating of the nozzles and air caps by the opposing spray stream.

One important factor in the avoidance of this air cap coating buildup, is the equal, similar, high voltage charges on both the exterior areas of the nozzles and the spray particles, so that the particles from one nozzle are repelled and deflected away from the exterior of the other nozzle.

This requires a type of atomizing nozzle which imparts high, uniform charges to all the spray particles. Another requirement in the performance characteristics of these nozzles, is that the spray jets assume and maintain a relatively tightly bunched aspect, in spite of the mutual parv ticle repulsion, until they reach the point where the jets impinge. Excessive jet spread Will result in undesirable nozzle coating.

It is also important that the size of the particles be relatively uniform, as excessively large particles appear to spread and collect on the opposing nozzle.

The type of nozzle shown herein appears to most closely meet the above requirements. Here, the physical arrangement of the components with the hollow cone in the center surrounded by a sharp atomizing and charging rim, imparts a uniform size and charge to the particles. The central concave cone appears to be particularly effective in causing the spray stream to converge and to maintain a relatively narrow stream.

At a given fan-oscillation rate and pulse differential pressure, a 104 degree angle head, at 12 inches from the workpiece, fully covered anarea 12 inches wide, a 135 degree angle head, under identical conditions, covered anarea 18 inches wide.

The material spray rate at each nozzle tends to be slightly increased at the moment when a higher air pressure oscillating pulse is fed to the nozzle. This is considered to be due to the increased Venturi action of the higher air velocity. It results in a more uniform coating across the oscillation stroke by compensating for the normally lower deposition rate toward the ends of the stroke caused by the angle at which the fan strikes the work surface in these end stroke areas.

In some instances as when the spray reaches the end of the surface to be sprayed the material feed of one of the nozzles may be cut off while retaining the oscillating air pressure so that the spray fan is reduced in intensity and over-spray is reduced at this point. Alternate nozzles of each pair may be cut off in this way when the spray reaches opposite edges of the surface to be sprayed.

What is claimed is:

1. Apparatus for spraying articles comprising a slide, means mounting said slide for vertical reciprocation, a horizontal bracket on said slide, an arm pivoted to said bracket for adjustment about a vertical axis, and a pair of spray nozzles carried by said arm, said nozzles being positioned to project intersecting spray patterns adapted to commingle to form a spray fan, a stationary source adapted to supply spray material at a predetermined pressure and means including a constant pressure valve mounted on said slide and connected to supply said material from said source to said nozzles at a constant pressure while the input pressure at said valve varies according to change in pressure head as the valve reciprocates vertically.

2. Apparatus as set forth in claim 1 including a coupling member connecting said bracket and said arm for relative axial adjustment, said coupling member having means for effecting pivotal movement of said arm about a vertical axis.

3. Spraying apparatus comprising a vertical support, means causing vertical reciprocation of said support, a spray head carried by said support, a control valve on said support connected to said nozzle and having means supplying spray material to said nozzle at a predetermined constant pressure, a stationary source supplying spray material at a predetermined pressure, and means supplying said spray material from said source to said control valve at a pressure determined by the pressure of said source and by the pressure head between the source and said control valve which varies according to the elevation of said reciprocating valve.

4. Spraying apparatus according to claim 3 in which said control valve includes means for adjusting the predetermined pressure at which the spray material is supplied therefrom to said nozzle.

5. Apparatus as set forth in claim 4 in which said adjusting means comprises a pressure actuated diaphragm and means including a remote pressure control valve connected to control the pressure applied to said diaphragm for thereby varying the pressure supplied by said first control valve to said nozzle.

6. Apparatus as set forth in claim 5 in which said pressure control valve is connected to said first control valve by a flexible coupling having insulating characteristics and an electrostatic potential is applied to said nozzle for charging the spray material ejected therefrom.

References Cited by the Examiner Wahlin 239536 Ericks et al. 118-313 Paasche 239186 Upperman.

Adams 239411 Siefen 239411 Brady et al. 239186 Klemp 239-186 Minnick et al. 1183 15 Inglis 239411 M. HENSON WOOD, JR., Primary Examiner.

EVERETT W. KIRBY, Examiner.

Disclaimer and Dedication 3,219,276.Edwm'd 0. Nowz's, Westport, Conn. PLURAL NOZZLES HAV- ING INTERSECTING SPRAY AND CONTROL THEREFOR. Patent dated Nov. 23, 1965. Disclaimer and dedication filed Apr. 2, 1969, by the assignee, The Gyromat Corporation.

Hereby enters this disclaimer and dedication to the Public to claims 3 and iof said extent.

[0 cz'al Gazette December .9, 1.969.]

Claims (1)

1. APPARATUS FOR SPRAYING ARTICLES COMPRISING A SLIDE, MEANS MOUNTING SAID SLIDE FOR VERTICAL RECIPROCATION, A HORIZONTAL BRACKET ON SAID SLIDE, AN ARM PIVOTED TO SAID BRACKET FOR ADJUSTMENT ABOUT A VERTICAL AXIS, AND A PAIR OF SPRAY NOZZLES CARRIED BY SAID ARM, SAID NOZZLES BEING POSITIONED TO PROJECT INTERSECTING SPRAY PATTERNS ADAPTED TO COMMINGLE TO FORM A SPRAY FAN, A STATIONARY SOURCE ADAPTED TO SUPPLY SPRAY MATERIAL AT A PREDETERMINED PRESSURE AND MEANS INCLUDING A CONSTANT PRESSURE VALVE MOUNTED ON SAID SLIDE AND CONNECTED TO SUPPLY SAID MATERIAL FROM SAID SOURCE TO SAID NOZZLES AT A CONSTANT PRESSURE WHILE THE INPUT PRESSURE AT SAID VALVE VARIES ACCORDING TO CHANGE IN PRESSURE HEAD AS THE VALVE RECIPROCATES VERTICALLY.

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