US2781738A - Spray coating apparatus - Google Patents

Description

Feb. 19, 1957 J. A. PAASCHE SPRAY COATING APPARATUS 5 Sheets-Sheet 1 Filed Sept 8, 1954 NVEN TOR.

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Feb. 19, 1957 J. A. PAASCHE SPRAY COATING APPARATUS 5 Sheets-Sheet 2 Filed Sept. 8, 1954 g INVENTOR. 31 (2 7345 d. j amsck Feb. 19, 1957 J. A. PAASCHE 297819733 SPRAY COATING APPARATUS Filed Sept. 8, 1954 5 Sheets-Sheet 5 United. States Patent SPRAY COATING APPARATUS Jens A. Paasche, Chicago, 111., assignor to Cline Electric Manufacturing Company, Chicago, Ill., a corporation of Illinois Application September 8, 1954, Serial No. 454,801 14 Claims. (Cl. 118-2) This invention relates to apparatus for coating articles by spraying and more particularly to an improved continuous spray coating apparatus.

It is customary today to coat many articles of manufacture. One of the most desirable methods of coating articles is to spray the article, preferably all portions of the article being sprayed so that they receive a protective coating. For example, ammunition shells are customarily sprayed with a protective coating of paint or shellac to protect the shells from atmospheric corrosion. Although the present invention is applicable generally to coating of articles, it will be explained in detail as applied to coating ammunition shells.

A high rate of coating and a uniformity of coating are best obtained by coating the shells while they are carried by a conveyor, the shell being rotated before an operative spray gun so that all portions of the shell are uniformly and thoroughly covered. Since the shell is rotated and otherwise handled in a rapid and rather violent manner, it is preferred that the shell be attached in a secure man ner to the associated conveyor. The manner of attachment must occupy as small an area as possible so that a maximum area of the shell can be coated.

To this end it is preferred that the bottom end of the shell be threaded and the conveyor support be attached to the shell by threadedly engaging the "shell at the threaded end. In order to maintain the rate of coating as high as possible, the shells must be positioned on the conveyor and attached thereto without interrupting the movement of the conveyor.

Accordingly, it is an important object of this invention to provide an improved and simplified manner of securing or mounting shells or similar articles on a conveyor in a spray coating apparatus.

After the shells or other article have been sprayed it is necessary to remove the coated article. This must be done without interrupting movement of the conveyor and must be done with safety to the operator and with great speed.

Therefore, it is an object of the present invention to provide an improved method and apparatus for removing shells from conveyors in spray coating apparatus.

Even when the spray coating apparatus and its operators are functioning efiiciently, it occasionally happens that one of the spaced apart article supports on the conveyor does not carry a shell or article to be coated. In such instances it is desirable to withhold or interrupt operation of the spray guns when the article support comes into position for spraying. This feature is desirable both to economize on the coating material and to prevent covering the conveyor and conveyor supports with a coat of coating material which may interrupt or impair the future operation of the coating apparatus.

Accordingly, means is provided to detect the presence of empty article supports as the article supports approach the spray coating station and further means is provided to render the spray guns inoperative when the empty article support is in position for spraying. Heretofore it ice has been customary to position the empty support detecting means and the spray gun control means in juxtaposition. However, in certain modern installations this positioning of the parts is not possible and remote control of the actuators for the spray guns by the empty support detecting means is necessary.

Therefore, it is another object of the present invention to provide an improved mechanism for detecting the absence of articles on supports and improved means to control the actuators for the spray guns in response to the article detecting means.

More specifically, it is an object of the invention to provide an improved means for detecting the absence of articles on article supports, the detecting means transmitting the condition of the article support to a distant actuator for the spray guns.

Still another object of the invention is to provide an improved selector control assembly for controlling operation of the spray guns in response to the article detecting means.

These and other objects and advantages of the invention will be better understood from the following description when taken in conjunction with the accompanying drawings. In the drawings wherein like reference numerals have been utilized to indicate like parts through- Figure l is a general side view of a spray coating apparatus incorporating the features of the present invention, certain portions of the apparatus having been removed and broken away for purposes of illustration;

Figure 2 is a plan view somewhat schematic of the spray coating apparatus shown in Figure 1;

Figure 3 is an enlarged view in part vertical section showing the selector control assembly embodying the subject matter of the present invention;

Figure 4 is a schematic view showing the various pneumatic and hydraulic connections among the various operative elements of the present invention;

Figure 5 is an enlarged view in vertical section showing the article conveyor wtih an article mounted thereon and positioned adjacent the mechanism for detecting empty article supports;

Figure 6 is a partial perspective view of the mechanism for detecting empty article supports;

Figure 7 is a plan view of the detecting apparatus shown in Figure 6, the apparatus being shown in the position assumed when an article support on the conveyor is vacant;

Figure 8 is a view similar to Figure 7 showing the position of the parts of the article detecting mechanism when an article is present on the article support;

Figure 9 is a perspective view with certain parts broken away or" the selector control assembly;

Figure 10 is a plan view of the selector control assembly shown in Figure 9; and

Figure 11 is a view in vertical section substantially as seen in the direction of the arrows along the line 1l-i1 of Figure 10.

Referring now to the drawings and particularly to Figures 1 and 2, a spray coating apparatus embodying the present invention will be described in general. There is provided a conveyor generally designated by the numeral 20 on which are positioned removable article supports 22. The conveyor 20 is continuous and is supported by a frame 24 that is in turn supported by legs 26. A loading station 28 is provided (see Figure 2) at which station the articles 30 are positioned upon the supports 22.

After leaving the loading station 28 the articles pass by the empty article support detecting unit 32 and then into a spray booth 34. Positioned within the spray booth 34 is a plurality of spray guns 36, 38, 40 and 42 that are '64 on which the .conveyor :chain rides.

arranged to spray various portions of the article After leaving the spray booth the articles pass by the selector control assembly 44 and then enter a continuous .drier v46.

The drier id is sufiiciently long ,so that the articles are completely dried beforeemergingtherefrom. After drying the articles pass to an unloading station 48 where the coated articles are removed thereby emptying the article supports. The empty article supports then pass in the direction indicated by arrow 50 to thearticle load ing station 28.

Referring now to Figure 5, the structure of conveyor 20 will be described in detail. The frame 24 includes a pair of upstanding side members 52 and 54 which are provided at their upper edges with inturned flanges 56 and .58 that terminate in downturned flanges 60 and 62. Extending between side members '52 and 54 is a bedplate Also extending between the side members 52 and "54 and spaced above the bedplate64 is a slotted channel-plate 66 which serves as a'guide and lateral support forthe conveyor chain.

The conveyorchain-includes aplurality'of chain'shafts 63 which serve to interconnect the various link members. The chain includes link members 70, 72, 74 and 76, links 72 and 74 extending out of the page, as illustrated, and the links and 76extendinginto the "page, asillustrated. The links are held apart by a spacer 78 and are held on shaft 68 by a cotter pin 80. The links alternate around the chain and form a continuous flexible conveyor member.

Mounted upon the shaft 68 and positioned 'for rotation therewith is a cylindrical member 82. Fixed to cylindrical member 82 by means of a set screw'84 is a pulley 86 which is adapted to engage means to rotate the pulley. A sleeve 88 fits'over the cylindrical member 82 and is held againstpulley 88-by means of 'a collar 90 provided with a set screw 92. The upper portion 94 of the cylindrical member 82 is tapered and shaped like a truncated cone.

Positioned upon the cone portion 94 is a removable support member 22 which has been mentioned before. The support member 22 includes a base section 96 having an aperture therein complementarily shaped with respect to the cone portion 94. The upper end of the support member 22 is provided with an outwardly extending 'fiange 98 and an upstanding threaded portion 100 thatis adapted to be screwed into a complementarily shaped aperture in the base of a shell 30.

It is tobe understood thatnot every chain shaft 68 is provided with an article support but that only certain spaced apart shafts 68 are so equipped. The article supports 22 are uniformly spaced along the conveyor 20 for reasons which will be more 'fully understood after the article detecting and the coating mechanisms have been described in detail.

The power for driving the conveyor 20 is derived from a motor 102 which is preferably electric. 'The output of the motor is fed to a speed change mechanism 104, :the output of .the speed change mechanism .104 being taken from a pulley 106 through a belt 108 to shaft 110. The end of shaft 110 drives .a toothed sprocket wheel (not shown) that in turn drives the conveyor 20.

The loading station 23 is provided with a b lt 112 that is positioned to engage the .pulleys86of the article support structure when an article support is within the loading station. A pair of pulleys 1714and 116 support belt 112, the pulley 116 being driven by thevoutput of speed change mechanism 104. Proper tension to drive the article supports and rotate the article supports is provided by a pair of tension rollers 118 that are spring biased toward .the bottom, as viewed in Figure 2.

An operator .is positioned at .theloading station 23 and is provided with a .guantityof shells 30 thatare to be coated. The removable support member 22 is :in posi- 4 tion .911 the conveyor .20 as the article support approaches the loading station. Either slightly before or slightly after the article support pulley 86 engages belt 112, the operator positions a shell 30 upon the threaded portion 169. The threads and the direction of travel of belt 112 are so positioned that .the ,shell 30 is threaded upon threaded portion 104 if the operator simply holds shell 30 stationary and in contact with threaded :portion 100. This provides a speedy and easy manner of loading the shells 36 on the conveyor. Safety is afforded for the operator due to the friction fitbetween bottom cone .portion 94 and the bottom portion 96 of support member 20. The friction fit, however, issuflicientito drive androtate article 30 when the article is not {held by the operator.

After leaving the loading station 28, the articles approach the article detecting mechanism 32 which will be described in detail later. If an article is present upon an article support, then the selector control assembly 44 is conditioned to actuate the spray guns 3610 42 when the article is in position to'be sprayed by the guns. The details ofthe selector gcontrol assembly will be discussed later.

After passing the article detecting mechanism '32 the articles enter the spray booth '34. "Spraying booth 34 has a'pair of walls 12% and 122 (see Fig. 1 to confine the 'fumes given off during the spraying operation and is-provided with an exhaust duct 124 which carries away any obnoxious fumes. Positionedwithin the spray booth 34 are the spray guns 3'6, 33, 4t and 452. All of the spray guns are mounted upon a support column "126 which in turn is carried by a carriage .128. Carriage 128 is mounted --upon aplurality of wheels 13ii1that ride upon and are supported by a rod 132. Rod 132 is supported by frame members 13'4- and 136 at either end thereof-and serve to hold rod 132 in operative position.

iii-order to obtain even coating of the articles 353 it is desirable to move the carriage 123 and its associated spray guns 36, '38, dd and 42 in synchronism with the conveyor 20 during the'spraying operation. To'this end there is provided on the upperportion of carriage 128 a pair of outwardly extending plates 138 and 140 that carry a plurality of rollers 142 and 144, respectively.

The rollers are arranged in pairs with two pairs of rollers positioned-side by side and receiving therebetween an arm 1% in the case of rollers 142 and an arm 148 in the case of rollers 144. The arms 1'46 and 148 are mounted to reciprocate in a vertical direction, :as viewed in Figu-re '2, this reciprocating motion being facilitated 'hy the rollers 1'42 and 144, respectively.

Mounted on the frame of the conveyor are a pair of track members 159 that serve -to guide "the upper end cf-carriage 128 by means of'a-pair of rollers 152 that are engaged on either side by the tracks 15d and are mounted .on the plates 138 and 149. Also attached in a fixed manner toithe'conveyor-frame is a plate 156 in which are cut a pair of L-shaped slots 158. Positioned to be guided by the slots 158 are a pair of rollers 16%) :and 162 that are mountedon and '-fixedly'attached to the arms 146 and M8, respectively.

Themanner in which :the above structure'provides for reciprocation of the carriage 1285is as follows. With the parts in the position shown in Figure '2 adjacent article supports engage the outer ends or the arms 146 and .148. Theconveyorthroughthe action of the article supports moves the arms and :t'ne associated carriage to the left, as viewed in Fi ure 2, until the rollers 6 and 162 enter the left-hand part of the slots 15%. The slots 15.8 are so shaped that the arms 1'46 and 14-3 are withdrawn from :contact with the article supports and thus free the arms :and the carriage from "the action of the conveyor. A dash pot arrangement 1 64, see Figure 1, then returns .the carriage in a gradual manner .to the right thereby positioning arms 146 and 148 to engage the next .pair of article supports. 'By means of this mechanism the carriage 128 is moved in perfect synchronisrn with the conveyor 20 and the associated articles 30 during operation of the spray guns. I

The support column 126 has mounted thereon each of the spray guns 36, 38, 40 and 42. Spray gun 38 is attached to column 126 by means of a clamp 166. Spray gun 38 has been shown diagramatically and may be any type that is actuated by pneumatic pressure. The position of spray gun 38 is such that it sprays the upper outside portion of each article 30. Arranged below spray gun 38 are two spray guns 40 and 42 that are also attached to column 126 by means of clamps 168 and 170, respectively. Clamps 168 and 170 are elongated; the horizontal distance between spray guns 40 and 42 and spray gun 38 is equal to the distance between alternate articles 36. The purpose of this will be more fully explained hereinafter. The vertical positioning of spray gun 40 is such that it sprays substantially the central portion of the articles 30 and spray gun 42 is positioned to spray the lower portion of article 30.

In the form of the invention shown in the drawings, the articles 36 that are to be sprayed are hollow and it is desirable to spray the interior of the articles. To this end the spray gun 30 is mounted on an elongated support 172 which in turn is clamped to a vertically reciprocable rod 174. Rod 174 is mounted for vertical reciprocation within column 126 and is provided at the lower end thereof with means to cause reciprocation thereof in timed relationship with the movement of conveyor 20. More specifically, there is provided a shaft 176 which is driven by the conveyor 29 through mechanism not illustrated. Mounted on shaft 176 is a cam 178 on which rides a cam follower 180. Cam follower 186 is in the form of a roller rotatably mounted on a lever arm 182. One end of lever arm 182 is pivot-ally mounted on carriage 128 at point 184 and the other end of lever arm 182 bears against a roller 186 that is fastened to the lower end of rod 174.

As conveyor 20 moves, the shaft 176 and the cam 178 are rotated in synchronism with movement of the conveyor. Cam 178 is so shaped that it will cause uniform vertical reciprocation of the rod 174 and associated parts in synchronism with movement of conveyor 20.

For purposes of illustration, spray gun 36 is shown in Figure l positioned to the left of column 126. In

actual use the spray gun 36 is positioned substantially ,1

directly behind column 126 and in position to be inserted within the interior of an article 30.

In order to prevent operation of the spray guns when an article support 22 has no article positioned thereon, there is provided the article detecting mechanism generally designated by the numeral 32. This detecting mechanism is pneumatically connected to the selector control assembly 44 and conditions the selector control assembly. it is the selector control assembly which causes selected operation of the spray guns. If a particular article support has no article positioned thereon, the selector control assembly under the influence of the article detecting mechanism 32 fails to operate the spray guns and thus no spraying operation is performed.

Referring now more particularly to Figures 1 and through 8, the operation and structure of the article detecting mechanism will be described in detail. From Figure 1 it will be seen that the article detecting mechanism 32 is positioned adjacent the entrance to spray chamber 34 and is actually positioned to be acted upon by an article twice removed from the spray guns 36 and 38. The purpose of this positioning of the article detecting mechanism will be understood more fully hereinafter.

In Figure 5 it will be seen that the article detecting mechanism includes a finger 188 that is fixedly clamped in an adjustable manner by means of clamp 190 to an upstanding rod 192. Finger 188 is positioned to contact the articles at substantially their mid-point and is positioned well above the uppermost portion of an article support 22. Rod 192 is fixedly attached in turn to housing 194 within which is positioned a valve head 196 and a valve seat 193. A hollow tube 201'} is fixedly attached to body 194 and extends downwardly therefrom to make connection with a coupling 202 which is attached to a line connecting with the selector control assembly 44. Whenever air passes through tube 200 to the selector control assembly 44, the selector control assembly is conditioned to render the spray guns inoperative when the particular article support then adjacent arm 188 is positioned in front of the spray guns. A pair of rings 264 and 206 encircle tube 200 and are afiixed thereto by set screws 268. The collars 264 and 2126 are spaced apart and receive therebetween a body 216 that completely encircles the tube 200 and is fixedly attached by means of a bracket 212 to wall 54 of the conveyor 29. The above mounting of tube 200 permits rotation of the tube 200 and associated parts including finger 188 with respect to the conveyor frame. The parts are normally biased to the position shown in Figure 7 by means of a spring 214.

Valve head 196 is biased against valve seat 1% by means of a spring 216. When the valve is closed, air through line 218 from a central source cannot gain entrance to tube 266 and thereby move the selector control assembly to the non-spraying position.

Valve 196 is provided with a stern 220 which extends outwardly from housing 194, as is better illustrated in Figures 7 and 8. Positioned in front of valve stem 228 is a cam lever 222 that is pivotally mounted on mounting plate 212 by means of an assembly 224 which spring biases lever 222 to the position indicated in dotted lines in Figure 7.

When cam 222 is in the position shown in Figure 7 by dotted lines and the arm 188 is as shown in Figure 7, valve 196 is closed and no signal is transmitted to the selector control assembly 44. If an empty article support 22 passes by cam lever 222, the arm 183 and its associated valve 196 and valve stem 22% remain in the position shown but the cam lever 222 is moved to the position shown by full lines in Figure 7. This movement of the cam lever 222 pushes valve stem 22% to the right, as shown in Figure 5 and opens valve 196. Opening valve 196 sends a stream of air to the selector controi assembly 44 and positions a corresponding spray gun actuator in the inoperative position, the details of this operation of selector control assembly 44 being described later.

If instead of an empty article support 22, a filled article support passes the article detecting mechanism, the article contacts arm 188 and deflects it to the position shown in Figure 8. Cam 222 is also pivoted but valve stem 220 has been pivoted out of possible contact with cam lever 222 and accordingly valve 196 is not opened. No signal is sent to the selector control assembly 44 and accordingly the spray gun actuator corresponding to this particular article support is left in the actuating position.

Referring now to figures 3, 4 and 9 to ll, the details of the selector control assembly will be described. In Figures 3 and 10, it will be seen that the selector control assembly is positioned generally adjacent a turn in the conveyor but it is to be understood that the selector control assembly could be positioned at any other point along the conveyor.

A toothed wheel 226 is mounted adjacent the conveyor with the teeth arranged to engage the conveyor and be driven thereby. Wheel 226 is mounted on a shaft 228 that carries at its upper end a gear 230. Gear 230 in turn drives a gear 232 mounted on a shaft 234. The upper surface of gear 232 carries a plate 236 that is rotated in synchronism with the conveyor through the gear train just described.

Mounted upon the upper surface of plate 236 is a plurality of posts 238 that carry cam rollers 240. The carn rollers are free to ,slide in a vertical direction upon-the Posts 238 and are generally circular in cross-section. Adjacent the upper-ends of each cam roller is a circumferentia'lly extending groove 2'42.

Spaced above and aligned parallel with plate 232 is a disk 2'44,the diameter of the disk being slightly less than the distance between the bottom of the grooves 242 of opposite cam rollers 2'40 and the thickness of disk 242 being slightly less than the height of the grooves 242.

Positioned adjacent the periphery of plate 236 are two air valves 246 and 2.48 having actuators 250 and 252, respectively. When the cam rollers are in the lowermost position they contact and move the actuators of the air valves and open the air valves. Air valve 246 is connected by means not shown to operate the spray guns 36 and 33 and the valve 248 is connected to operate spray guns 40 and 42; Accordingly, if the cam rollers 24% are left in the lowered position, the spray guns will be operated and "the associated articles sprayed.

in order to ,render the spray guns inoperative, it is necessary to move the cam rollers upwardly so that the groove 242 engages the disk 244. This is accomplished by means of a'lifter generally designated by the numeral 254. The construction of lifter 254 is best illustrated in Figure .11 wherein it is seen that it comprises a housing 256 in which is provided a .piston 258 carrying a ,stem'26tl. The bottom of the'housiug 256 has an attachment 262 which is connected by a hose 264 to coupling 262, see Figure '5. Accordingly, Whenever valve 196 is opened, air pressure will be admitted into housing 256 below piston 258.

Stem 260 passes downwardly through .a seal 26-! and carries on the lower end thereof a lifting disk 266. The upper end of stem 260 extends upwardly above piston 258 and is adapted to hit against an abutment member 263 at the uppermost position thereof. Abutment member 268 is adjustable as to position bymeans of a screw 27:; attached to a cap 272 that closes the upper end of body 256. A spring 274 urges piston 258 to the lowermost position and a vent 276 is provided to permit piston 258 to move upwardly.

Referring now to Figure 10, it will be seen that the lifter '254 is supported by a car 278 adjacent a cut-out portion 286 in disk 244. The cut-out portion 280 permits a cam roller 24% to be lifted upwardly whereby to permit disk 244 to be'engaged within groove 2 52.

More particularly plate 236 rotates in the direction shown by the arrow in Figure '10 and each cam roller 24,0 passes by lifting .disk1266 in position for the disk to'fit within groove 242. If it should happen that an empty article support at the time passes the article detecting mechanism, :a pulse of air will be admitted through line 262, see Fig. 11, into the lifter 254 and cause the disk 266 to 'be'moved "upwardly; the distance of upward movement of disk 266 is adjusted bymeans of the abutment 268 so that the groove 242 in the cam roller is opposite and in line with the area designated 232 of disk 244. Further rotation of the plate 236 will cause movement of the cam roller 24% in 'an elevated position out of contact with the valve actuators 250 and 252. With the cam rollers 240 so elevated there will be no actuation of the spray guns when the corresponding article support is in front of the spray guns.

Referring now to Figure 4 the various connections among the article detecting device, the spray guns and the selectorcontrol assembly will be described. It is to be understood that this figure is to a certain extent schematic and for the purposes of simplicity only one spray gun and its associated control valve has been shown.

A source of air such as a compressor (not shown) is connected to an air conditioner 281 which filters the air and removes any moisture therefrom. Air from the air conditioner 2,81 passes into a manifold pipe .285 to which are connected .a plurality of air regulators 284 and 286. The air regulators include a reducing valve and ogre-tyres a connection for attachment of air lines. The air regulator 286 is connected *by means of an airline 283 to coupling 218 that supplies air 'to valve 194 in the article de-' tecting mechanism As has been described above, the other side of the valve 194 is attached through a line 264 to the valve lifter 254.

Air regulator 284i is connected by airline v290 to the air control valve 246 which has been described before. The outlet leading from valve 246 is provided with an air line 292 that is connected to spray gun 3% through a shut-off valve and associated coupling 29 2-. Paint for the spray gun 33 is provided from a tank 296 through a line 298i The manner in which synchronism between operation of'the article detecting means and the valve lifter and operation of the spray guns will now be described in detail. The various gears that drive the plate 236 upon which are mounted the cam rollers 24% are so designed that the cam rollers pass the roller lifter 254 and the air control valve 246 at the same, rate and in the same sequence that article supports pass the arm 138 of the article detecting mechanism 32. Accordingly, when an article support is adjacent the detecting arm 188', a corresponding cam roller 240 is opposite and engaging the roller lifter 254 and its associated lifting disk 266. From Figures 4 and 9 it willbe seen that there are two positions between the roller'lifter 2'54 and the air control valve 246. This corresponds to two positions on the'convcyor 20 and from Figures 1 and 2 it'will be seen that two positions from the article detecting mechanism 32 is directly in front of the spray gun 38. Accordingly, when the cam roller 24%) has rotated to a position to engage the actuator of valve 246, the corresponding article 30 will have moved into position to be sprayed by the spray gun 38.

Referring to Figure 9, it will be seen that the air control valve 248 is set to contact a cam roller two positions after control valve 246. When a cam roller has traversed this distance, the corresponding article will have moved to a position in front of the spray guns 4t) and 42. Control valve 248 is connected to control operation of the spray guns &0 and 42 and accordingly will cause operation of the spray guns if an article is present on the article support.

After passing the control valve 248 the cam rollers 24G proceed around the circumference of disk 24 and approach a cut-out portion 3.69. Any cam rollers which are engaged by disk 244 will drop back into contact with plate 236 when they reach cut-out portion 390. This places the cam rollers in position to be acted upon by the roller lifter 254.

Adjustment of the position of the lifter 254 and the control valves 246 and 248 with respect to the cam rollers is provided by a knob 362. Each of the valves 246 and 248 is held in operative position by a support arm 394 and 306, respectively. The various support arms 278, 304 and 3il6'are'held in the adjusted position by tightening the adjustment kno'b 302.

In order to coat the surfaces of the articles 3% more evenly, the articles are rotated when they are positioned in front of the spray guns. 'To this end there is provided a belt 308 that engages the pulley 86 on the article supports. Belt 303 is supported by a pair of pulleys 310 and 3112, the pulley 312 being driven by a motor 314 through a belt 316. The speed of rotation of motor 314 is adjustable so that the rate of rotation of the articles 34) can be adjusted in synchronism with the rate of movement of conveyor 20.

A complete cycle of operation will now be described for the condition in which an article 30 is positioned upon an article support 22. The conveyor 29 moves the article 30 from the loading station 28 to the left, as viewed in Figures 1 and .2 toward the article detecting mechanism .32. Simultaneously, .the corresponding cam roller 2401s approaching the lifting disk 236, see Fig. 9.

As the article 38 contacts detecting arm 188, the cam roller 249 engages the lifting disk 266. Since an article is present upon the support 22 arm 188 moves the valve stem 22% out of contact with cam lever 222 and accordingly no operation of lifter 254 is obtained. Upon further movement of the conveyor the article 30 moves in front of the spray gun 38, see Fig. l. in this position the spray gun 36 is positioned directly above the article in position to be lowered into the aperture therein. The cam roller 24!; now engages the actuator 250 of air control valve 246 and commences operation of the spray guns 36 and 38. The article support 22 has engaged belt 308 and the articles are rotated in a constant and uniform manner.

Referring to Figure 2, the carriage arms 146 and 148 will have engaged article supports to begin movement of the carriage 128 to the left in synchronism with movement of conveyor 20. Simultaneously, spray gun 36 is lowered through the action of the cam 178 and associated parts.

After moving through one position the arms 146 and 148 are retracted and the carriage 128 returns to the rest position. Meanwhile, the article 30, still being rotated, moves through two stations and is positioned before spray guns 4% and 42. Simultaneously, the corresponding cam roller 240 has moved into contact with the actuator 252 of air control valve 248. This causes opera tion of spray guns 40 and 42 while the articles are rotated. Cam roller 240 moves out of contact with actuator 252 and thus ends operation of the spray guns 40 and 42.

After leaving the spray booth 34 the coated article 30 is carried by conveyor through the drying section 46 and then through the unloading station 48. At unloading station 48 there is provided a belt 318 that engages the pulley 86 on the article support. Belt 318 is supported by pulleys 326 and 322 and is driven by the motor 102 and shaft 119. A pair of tensioning rollers 324 are pro vided to hold belt 318 in contact with the pulley 86.

The direction of rotation of belt 318 is such that the threaded member 100, see Fig. 5, is unscrewed from the bottom of article 30 if an operator grasps 3.111016 30 and prevents its rotation. Very quickly the article 30 is free of the support 22 and can be then deposited in a suitable receptacle. The empty article support 22 moves to the loading position 28 and a new cycle begins.

A situation in which no article is placed on the article support 22 will now be described in detail. When the empty article support approaches the article detecting station 32 the corresponding cam roller 240 approaches and comes in contact with the lifting disk 266 of the lifter 254. When the article support moves cam lever 222 to the position shown by solid lines in Figure 7, valve 196 is ouened and a pulse of air passes through line 264 to lifter 254. The air acting against piston 258, see Fig. ll, moves valve stem 260 and the lifting disk 266 to the upper position with the valve stem 266 against the abutment 268. The lifting disk 266 moves the associated cam roller 24% upwardly so that the groove 242 in the cam roller is aligned with disk 244. Further rotation of plate 236 moves cam roller 240 onto disk 244 and disk 244 hold the cam roller in the upper position.

When the empty article support is in front of spray gun 33 the cam roller will be positioned in front of valve actuator 259 but will be lifted upwardly out of contact therewith. Accordingly, there will be no actuation of the spray guns and no spraying of the empty article support. Likewise, when the articles comes before the spray guns 4t) and 42, there will be no operation of these spray guns since the cam roller 240 will be up and out of contact with the valve actuator 252.

it will be seen that there has been provided a coating apparatus which fulfill all of the objects and advantages set forth above. More particularly, there has been provided a novel loading and unloading system and structure which permits safe, easy and rapid loading and unloading of articles on the conveyor. There also has been provided an improved spray gun control mechanism and means for rendering the spray gun control mechanism inoperative when empty article supports are before the spray guns. The article detecting mechanism and the control assembly are both hydraulically operated and can be positioned at points greatly separated from each other.

Although certain preferred forms of the invention have been shown for purposes of illustration, it is to be understood that the invention is to be limited only as set forth in the accompanying claims.

I claim:

1. A spraying apparatus for applying a coating to articles on a continuous conveyor having a plurality of equally spaced article supports mounted thereon, a spraying chamber having a plurality of movably mounted spray guns, detector means mounted adjacent the entrance of said spraying chamber for detecting vacant article supports, said detector means including a movably mounted member engageable with and shiftable by articles on said article supports, valve means having an inlet connectable with a source of air under pressure and mounted for movement in response to movement of said movable member, and means actuated by said article supports for opening said valve means when the supports are vacant and inoperative to open said valve means when an article on a support shifts said member and said valve means, control mean responsive to said detector means and mounted at a distance from said detector means for controlling the actuation of said spray guns in accordance with the condition of said detector means, said control means having cam members positioned thereon, said cam members having an operative and an inoperative position, and pneumatic means connected with an outlet of said valve means and actuated upon opening of said valve means for moving said cam member to the inoperative position when said detector means detects a vacant article support.

2. A spraying apparatus for applying a coating to articles on a continuous conveyor having a plurality of equally spaced article supports mounted thereon, a spraying chamber having a plurality of movably mounted spray guns, detector means mounted adjacent the entrance of said spraying chamber for detecting vacant article supports, said detector means including a movably mounted member engageable with and shiftable by articles on said article supports, valve means having an inlet connectable with a source of air under pressure and mounted for movement in response to movement of said movable member, and means actuated by said article supports for opening said valve means when the supports are vacant and inoperative to open said valve means when an article on a support shifts said movable member and said valve means, control means responsive to said detector means and mounted at a distance therefrom for controlling the actuation of said spray guns in accordance with the condition of said detector means, said control mean including a rotatably mounted disk with a plurality of cam members mounted thereon, said cam members being shiftable to occupy either an effective or an ineffective position, a retaining member fixed adjacent said disk and having an arcuate edge portion substantially concentrically dis posed with respect to said disk, each of said cam members having shoulder means for positively engaging said retaining member edge portion for holding the cam members in said ineffective position, and pneumatic means adjacent said disk and connected with an outlet of said valve means and actuated upon opening of said valve means for moving said cam members to the inoperative position and into interengagement with said retaining member in response to actuation of said detector means when the detector means encounter a vacant article support.

3. In a spraying apparatus, a continuous conveyor having a plurality of spaced article supports mounted thereon, a plurality of spray guns, a carriage for said spray guns mounted for movement adjacent said conveyor, a detector member mounted adjacent said conveyor for deteoting vacant article supports, a control means including .a rotating disk having a plurality of two-position cam members positioned around the periphery thereof, said cam members having an operative and an inoperative position and actuating said spray guns in the operative position, retaining means positioned adjacent said disk for positive interengagement with said cam members to hold them in the inoperative position, and pneumatic means responsive to said detector means for causing engagement between .said cam members and said retaining means to hold the-cam members in the inoperative position when the detector member encounters a vacant article support.

4. A spray gun control assembly for use in a spraying apparatus comprising a rotating support member, a plu rality of'two-position cam-members mounted on said support member, said carn members having an operative and an inoperative position, a retaining member positioned adjacent said support member for positive intercugageme-nt with said cam members when the cam :members are in their inoperative position, an actuated member positioned adjacent said support member, said cam members in the operative position engaging and actuating said actuated member, and pneumatic means for moving said cam members into interengagement with said retaining member, said retaining member holding the cam member in contact therewith in the inoperative position.

5. A spray "gun control assembly for use .in a spraying apparatus comprising a rotating support member, a pinrality of two-position cam members mounted on said support member, said cam members having an operative and an inoperative position, a retaining member positioned adjacent said support member for positive interengagement with said cam member when the cam members are in their inoperative positions, on actuated member positioned adjacent said support member, said cam members in the operative position engaging and actuating said actuated member, and pneumatic means for moving said cam members into interengagement with said retaining member, said retaining member holding the cam member in contact therewith in the inoperative position, said retaining means including means to return the cam me bers to the operative position after a predetermined time.

6. A spray gun control assembly for use in a spraying apparatus comprising a rotating support member disposed in a horizontal plane, a plurality of cam members mounted on said support member for vertical reciprocation therewith, each of said cam members having annular shoulder mean thereon, a retaining member positioned adjacent said support member and having means formed thereon to engage beneath the shoulder means on said cam members when said cam members are in anelevated position, an actuated member positioned adjacent said support membe', said .cam members engaging and actuating said actuated member in their lower position, the cam members in an elevated position being inoperative to actuate said actuated member, and means to move said earn members to the elevated position into engagement with said retaining member whereby said actuated member is not engaged by the elevated cam member.

'7. A spray gun control assembly .for use in a spraying apparatus comprising a rotating support member disposed in a horizontal plane, a plurality of upstanding posts mounted on said support member, cam members mounted on certain of said posts for free vertical re- :ciprocation with respect to said support member, a retaining member positioned adjacent said support member and spaced from said posts and having means formed thereon positively to engage shoulder means on said cam members when said cam members are in an elevated position, an actuated member positioned adjacent said support member, said cam members engaging and actuating said actuated member in their lower position, the cam members in anelevated position being inoperative to actuate said actuated member, and means to move said cam 12 members to the elevated position in engagement with said retaining member whereby said actuated member is not engaged by the elevated cam member.

8. A spray gun control assembly for use in a spraying apparatus comprisinga rotating support member disposed ina horizontal plane, a plurality of cam members rotatably mounted on said support member for vertical reciprocation with respect thereto, each of said cam members having an annular groove in its peripheral surface, a retaining member positioned adjacent said support member and having means formed thereon to engage within the grooves in said cam members when said .cam members are in an elevated position, an actuated member positioned adjacent said support member, said cam members engaging and actuating said actuated member in their lower position, the cam members 'inan elevated position being inoperative to actuate said actuated member, and pneumatic lifting means including an element for entering the grooves in said cam members for moving said cam members to an elevated position to engage said retaining member whereby to move the cam members out of contact with said actuated member.

9. A spray gun control assembly for use in a spraying apparatus, as set forth in claim 8, wherein the retaining member includes means to return the cam members to the lower-operative position after a predetermined time.

'10. A detecting unit 'for use in a spraying apparatus having a conveyor :with article supports and a control mechanism for spray guns, comprising a detecting member positioned adjacent'the conveyor to engage an article mounted upon the article support, a cam member mounted adjacent said conveyor and positioned to contact the article supports, and actuating means mounted on said detecting member and connected to said control mechanism, said actuating means being positioned to be engaged and operated "by said cam member only when an article support has 'no article positioned thereon.

11. A detecting unit for use in a spraying apparatus having a conveyor with article supports and a control mechanism for spray guns, comprising at detecting member positioned adjacent the conveyor to engage an article mounted upon the article support, a cam member mounted adjacent said conveyor and positioned to contact the article supports, said cam member having a rest position and a support contacting position, means biasing said cam member toward the rest position, and actuating means mounted on said detecting member and connected to said control mechanism, said actuating means being operated by said cam member whenthe cam member engages an article support while the detecting member is positioned above an empty article support and said actuating means being moved to an inoperative position out of contact with said can member when the detecting member engages an article on the adjacent article support.

12. A detecting unit for use in 'a spraying apparatus having a conveyor with article supports and a control mechanism for spray guns, comprising a detecting member movably positioned adjacent the conveyor to engage an article mounted upon an article support, said detecting member having a rest position and an article contacting position, means normally urging said detecting member to the rest position, acam member mounted adjacent said conveyor and positioned to contact the article supports, said cam member having a rest position and a support contacting position, and valve means mounted on said detecting member and connected to said control mechanism, said valve means including an actuator, said cam member in the support contacting position being positioned to move said actuator to operate said valve means if the detecting member is in the rest position, said actuator being moved out of contact with said cam member when the detecting member is in the article contacting position and the cam member is in the article support contacting position. a

13. An apparatus for spraying articles having a threaded recess therein comprising a continuous conveyor movable past loading, spraying and unloading stations, a plurality of shafts mounted on said conveyor, a first support member rotatably mounted upon each of said shafts, a pulley mounted on each of said first support members, a second support member mounted upon each of said first support members and driven thereby by friction means, each of said second support member having a threaded portion on the upper end thereof shaped compiementarily to the threaded recess in the article, and drive means at said loading station for engaging said pulleys to rotate said first and second support members in one direction with respect to the conveyor to thread said threaded portions into recesses of articles applied thereto and held against rotation.

14. An apparatus, as defined in claim 13, which in- 14 eludes drive means at said unloading station for engaging said pulleys to rotate said first and second support members in an opposite direction with respect to the conveyor to unthread said threaded portions from articles held against rotation at said unloading station.

References Cited in the file of this patent UNITED STATES PATENTS 2,059,293 Thomas Nov. 3, 1936 2,217,342 Ladrach Oct. 8, 1940 2,271,442 Sanborn Jan. 27, 1942 2,376,980 Petersen et al May 29, 1945 2,383,023 Sykes et al Aug. 21, 1945 2,547,884 Paasche Apr. 3, 1951 2,675,778 Peeps Apr. 20, 1954

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