US3356061A

US3356061A - Paint spray control system

Info

Publication number: US3356061A
Application number: US439017A
Authority: US
Inventors: Richard F Wiggins
Original assignee: Gyromat Corp
Current assignee: Gyromat Corp
Priority date: 1965-03-11
Filing date: 1965-03-11
Publication date: 1967-12-05
Anticipated expiration: 1984-12-05

Description

Dec. 5, 1967 R. F. WIGGINS PAINT SPRAY CONTROL SYSTEM 3 Sheets-Sheet 1 Filed March 11, 1965 INVENTOR. RICHARD F. WIGGINS 777 L o nmsvs Dec. 5, 1967 3 Sheets-Sheet 2 Filed March 11, 1965 S m R6 mm m v m -w A H m R M Y B m v U l D W N R W I D ATTORNE S Dec. 5, 1967 R. F. WIGGINS PAINT SPRAY CONTROL SYSTEM Filed March 11, 1965 3 Sheets-Sheet 5 SPRAY RANGE SWITCH FIG. 6

FIG. 7

SPRAY RANGE INVENTOR. RICHARD F. WIGGINS ATTO RNE$SV United States Patent 3,356,061 PAINT SPRAY CONTROL SYSTEM Richard F. Wiggins, Fair-field, C0nn., assignor to The Gyr mat Corporation, Stratford, Conn., a corporation of Connecticut Filed Mar. 11, 1965, Ser. No. 439,017 1 Claim. (Cl. 118-2) ABSTRACT OF THE DISCLOSURE This invention is directed to a mechanical. memory unit in combination with a timer control, which combination functions to control the sequential spraying of a plurality of conveyed articles which may have their leading and trailing edges non-uniformly spaced. The memory unit detects, in the absolute sense, the presence or absence of an article to be sprayed and accordingly remotely controls the starting of a spray gun while the timer control determines the precise instant of starting the spray and the duration of the spray based upon the relationship of the leading and trailing edges to the spray guns.

spray gun, only in the presence of a conveyed article .and not otherwise. In the case of electrostatic spraying,

it may also be important to control spray application accurately to control wrap-around of the spray material.

Accordingly, for optimum operating efiiciency and maximum safety, the operation of the spray gun itself should be directly controlled by the relation or orientation therewith of the article to be coated in order that the spray nozzle be actuated only at times when the article is within desired range of the nozzle.

Detection of an article in the immediate presence of the spray gun presents little problem when a gun is manually controlled and selectively actuated by an operator using his own vision to detect an article passing a spray station. However, when the spray gun is to be automatically operated and controlled, the substitution of mechanical or electronic article detectors in the immediate presence or in the general vicinity of the spray gun has not been found to be especially reliable, since the detcctors, themselves, easily tend to become contaminated, fouled, or otherwise inoperative through the build-up and accumulation of spray coatings thereon.

In accordance with the present invention, reliable control of a spray coating apparatus, having one or more spray guns, by a conveyor-supported article may be achieved with a new and improved, remotely situated, conveyor actuated spray programmer. Specifically, the new programmer includes a rotatable memory wheel, which is synchronously indexed or otherwise synchronized with the travel of a continuously moving conveyor having pendants thereon, and a plurality of regularly spaced memory pins carried by the memory wheel. The memory pins are selectively projectable by a solenoid into an .article detected position from a normal, article undetected position in accordance with the presence or absence, respectively, of an article on a conveyor pendant (either by detection of the article itself or its supporting pendant) as it passes a mechanical or electronic detection device, such as a limit switch, photo-cell, or the like, remotely positioned with respect to the spray gun.

Associated with the memory wheel and supported on spaced radial spray switch arms are impulse switches which, in response to actuation by the memory pins, start the individual spray guns at predetermined delayed instants and for predetermined durations determined by the specific size of the articles being sprayed and the conveyor speed. In accordance with an important aspect of the invention, the spaced relation of the detection means with respect to the spray apparatus and the spaced relation of the memory wheel solenoid with respect to the spray switch arms are proportionally prearranged in such a manner that the spray guns are operated only when an article is detected and passes within its spray range and at no other time. Accordingly, whenever there has been an omission of a suspended article from the conveyor, deliberate or otherwise, the spray apparatus will not be activated when the empty portion of the conveyor passes it, since the memory pin associated with that portion of the conveyor will not have been projected by the solenoid.

It will thus be appreciated that the control system of the invention is essentially in the nature of an analog of a portion of the spray system itself, in which that portion of the continuously moving conveyor between the detection point and the spray point is analogically represented by the memory wheel, an article on the conveyor is analogically represented by a projected memory pin, and the individual spray guns are analogically represented by the spray switch arms. Moreover, it will be understood that the new spray programmer provides conveyor actuated, positive, sensitive, and contamination-free control of any number of spray guns in a reliable, simplified, and most efiicient manner.

For a more complete and better understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective representation of a paint spray system including a new and improved spray control programmer embodying the principles of the present invention;

FIG. 2 is a front elevational view of the memory wheel of the new and improved spray programmer;

FIG. 3 is a cross-sectional view of the memory wheel taken along line 3-3 of FIG. 2;

FIG. 4 is an enlarged, cross-sectional view of a memory pin taken along line 44 of FIG. 2;

FIG. 5 is a schematic representation of an article to be sprayed approaching the spray range of a spray gun;

FIG. 6 is a schematic representation of an article to be sprayed entering the spray range of a spray gun; and

FIG. 7 is a schematic representation of an elongate article to be sprayed supported from a pair of adjacent conveyor pendants.

Referring to FIG. 1, the spray programmer of the present invention is generally indicated by reference numeral 10 and is adapted for use with an endless conveyor 11 having any suitable number of regularly or otherwise spaced pendants 12 thereon, each of which is adapted to receive an article hanger 13 supporting an article 8. As-

.sociated with the conveyor, which is continuously driven clockwise by an appropriate motor drive 9, are spray guns 14 and 15.

As an important aspect of the invention, initiation of the timed operating sequence for the spray guns 14 and 15 is accomplished extrinsically of the immediate vicinity .or atmosphere of the spray guns and of the spray booth means. Projectable memory pins 19 are equiangularly arrayed at predetermined spacings about the memory wheel 17, and spaced

spray switches

20, 21 are adapted to cooperate with projected ones of the memory pins.

In accordance with the invention, a detection limit switch 22 is located remotely of and free from contamination by the spray guns 14, in the path of the hangers 13 to be reliably actuable thereby. The detection switch 22, which in certain applications may be a photo-cell, proximity switch or the like, is appropriately connected to a solenoid 23 having an armature adapted to project a memory pin into an active position to represent analogically each hanger 13 and hence each article detected by the switch 22.

In the illustrated arrangement, an indexing limit switch 63 is appropriately connected to the indexing drive 18 and is located immediately adjacent the path of spaced conveyor pendants 12, if they are regularly spaced, or other elements of the conveyor or its drive from which a regular indexing signal can be derived. The indexing drive 18 is periodically actuable by the switch 63 in accordance with advancement of the conveyor to cause the clockwise indexing of the memory wheel a single pin spacing to correspond with a predetermined increment of conveyor advance.

More specifically and with reference to FIG. 2, the memory wheel 17 includes a predetermined number of memory pins 19, equal to or greater than the number of conveyor pendants 12 between the detecting and spraying stations. These pins are equiangularly supported in holes 19a spaced circumferentially of the wheel. As shown best in FIG. 3, the memory wheel 17 is mounted for rotation about a shaft 26 supported by an appropriate frame 25, which shaft mounts a substantially circular holding plate 27 in a spaced relation to the memory plate. In accordance with the invention, each of the memory pins 19 includes an outer switch actuating portion 29 and an inner control portion 30 (FIG. 4) and is movable axially of the memory wheel 17 between limit positions imposed by the engagement of two

annular shoulder stops

31, 32 with the surfaces of the memory wheel.

As shown in FIGS. 2 and 3, the outermost edge portions 28 of the holding plate 27, in accordance with the invention, extend to a point between the control portions 30 of the memory pins and the outer diameterof the annular stops 32. Adjacent the solenoid 23 and in the area of at least two and advantageously as many as six pin spaces, the holding plate 27 is provided with a predetermined reset or erase portion 48 and a programming portion 58 having a substantially reduced diameter to accommodate resetting and subsequent reprojection or programming of the pins 19 at the termination of one cycle and the commencement of the next cycle of the memory wheel, as will be explained in more detail hereinafter. Supported in cantilever fashion from the reset portion 48 of the holding plate and terminating at the programming portion 58, is an arcuate retraction cam 33 having a leading edge 34 which gradually slopes downward in the direction of memory wheel rotation from the projected height of the pins to the retracted height of the pins.

In accordance with the invention, L-

shaped switch arms

35, 36 support and maintain

spray switches

20, 21, respectively, at a predetermined adjustable distance from the solenoid 23 which corresponds to the distance between the spray guns 14, 15, respectively, and the detection switch 22. The

switches

20, 21 are limit switches having

roller actuators

37, 38, which are displaceable momentarily by the actuating portions 29 of the projected memory pins, to initiate a predetermined time spraying sequence. The

spray switch arms

35, 36 are adjustably rotatable on the shaft 26 to any radial position corresponding to the location of a spray gun and are securable in that position by means of set screws 39.

A spray timing sequence for the spray guns 14, 15

is preset in accordance with the size of the article being coated and the speed of the conveyor 11 to limit the duration of spraying. Assuming each spray gun has a predetermined limited range concentrated in the area of its nozzle at a predetermined distance from the detection switch 22, it is an advantageous aspect of the invention to be able to start the spray only when the article has come within this specific range and not sooner, and to terminate the spray when the article leaves the spray range. This conserves spray material, reduces contamination and, in the case of electrostatic spraying, controls wrap-around with desired precision. To this end, a time delay mechanism 50-41, 501) for each spray gun is preset to delay the spray starting signal from the

spray switches

20, 21 for a preset time period (T in FIG. 5) which is equivalent to the time required for the conveyor to move the leading edge 51 of an article 8 from a fixed center point at the edge of the spray chamber or spray zone into the range of the nozzle. At the expiration of their delay intervals, the respective delay timers actuate spray timers 52a, 52b which start and maintain the sprays for intervals (T of sufiicient duration to allow the trailing edge 53 of the article to have passed through the spray range.

Where parts are very closely spaced, the spray timers 52 may be set for a period long enough to spray a designated article and at least a part of the next successive article. In such a case, the spray timers will be reset to start before fully timing out, and the spray guns will remain in uninterrupted operation.

For unusually long parts, such as article 68 shown in FIG. 7, which extend over a plurality of pendants, pairs

fo hangers

13, 13a may be employed. As will be understood, in this type of case the spray period T extends beyond the time required for a single predetermined increment of advance of the conveyor, and certain modifications will be appropriate. For example, to prevent the delay timer from being actuated by a memory pin projected by the trailing hanger 13a, the delay mechanism 50 may be appropriately set to be inoperative whenever the spray timer 52 is running, i.e., when the period T has not elapsed. Alternatively, specially configured trailing hangers might be employed, which trailing hangers would not actuate the detection switch 22 and, therefore, would not cause the projection of more than one memory-pin for each article on the conveyor.

Operation of the spray coating apparatus is as follows: The articles 8 to be sprayed are placed on hangers 13 which are in turn, loaded onto the conveyor pendants 12 at a remote loading station 60 (FIG. 1). As is to be understood, it is not necessary that an article be suspended from each pendant 12, since the memory wheel of the invention will change its program of projected memory pins in accordance with the specific array of articles at any particular time as the conveyor traverses the spray booth.

More specifically, as a hanger 13 passes and actuates the detection switch 22, indicating the presence of an article, the solenoid 23 will project, in the area of the programming portion 58 of the plate 27, a pin 19 into the position shown in FIG. 4. When the memory wheel is next indexed by the regular actuation of the indexing switch 63 by regularly spaced pendants 12, the inner surface 32b of the shoulder stop 32 of the pin will be engaged by the holding portions 28 of the plate 27 to maintain the pin in its projected position as the wheel is intermittently rotated by the indexing drive 18. Upon the subsequent indexing of the memory wheel, the projected pin will reach the spray switches 20, 21 at the same time the article approaches the spray guns 14, 15, due to the generally synchronous travel of the conveyor and the memory wheel and the proportional spacing of the detection switch and the solenoid with relation to the spray guns and spray switches, respectively. The projected pins will then initiate the timers 50, 52 to cause the actuation of the spray.

After the spray treatment, the article will be conveyed forward, through a drying oven 53, before it is finally removed from the conveyor at the unloading station 61. During this time, the projected pin representing that article is indexed about the holding portions 28 of the holding plate until it reaches the reset portion 48 where it will engage the cam 33. Continued indexing of the wheel will allow the pin to be cammed or reset into its inactive position (bottom of FIG. 3) at the end of its cycle. During the following cycle, the pin may be reprojected by the solenoid 23 at the programming portion 48, as explained, or it may not be projected by the solenoid in the absence of an article, in which case the unprojected or inactive pin will be limited to that position by the cooperation of the outer surface 32a of the shoulder 32 with the holding portion 28.

The coordinated stepwise movement of the memory Wheel with the conveyor travel will assure positive and sensitive actuation of the spray switches in accordance with the presence or absence of an article on the conveyor to effect a reliable, conveyor-actuated control of the spray guns. Moreover, and as an important aspect of the invention, the spray guns will be operated only in the immediate presence of articles to be treated and not during voids or gaps created by the specific spacings or sizes of the articles. As will readily be appreciated, the new and improved spray programmer may effectively and economically be incorporated with conventional conveyorized spray apparatus to automate its control with relative ease and great realibility. In this respect, the capacity of the programming system is independent of the capacity of the conveyor system, as long as there are at least as many memory pins as there are conveyor pendants in the space between the detection station and the spray station.

It should be understood that the specific form of the invention herein illustrated and described is intended to be representative only, as certain changes may be made therein without departing from the clear teachings of the disclosure. According, reference should be made to the following appended claim in determining the full scope of the invention.

I claim:

An automatic control for a conveyorized spray treatment apparatus comprising (a) a closed conveyor system including spaced suspension means for engaging articles to be sprayed;

(b) means to drive the conveyor system at a predetermined rate;

(0) a mechanical memory unit analogically representative of at least a portion of the conveyor system and including a plurality of individual control elements;

(d) means to drive the memory unit in accordance with movements of the conveyor system;

(e) spray means associated with the conveyor system and located remotely of said memory unit, said spray means having a predetermined spray range;

(f) means for detecting suspended articles located adjacent the conveyor system and remotely of the spray means;

(g) said individual control elements on the control unit being analogically representative of a different points on the conveyor system and being individually actuable between active and inactive positions;

(h) means for selectively positioning said control elements in active positions in response to the sensing of suspended articles by said detection means;

(i) starting means associated with said control unit and actuatable by control elements in active positions;

(1) a first controllable timer means actuatable by said starting means and operable to actuate said spray mean-s after a first predetermined elapse of time sufficient to accommodate the conveyance of an article to be sprayed into said spray range; and

(k) a second controllable timer means actuatable by said first timer and operable to deactuate said spray means after a second predetermined elapse of time suificient to accommodate the traverse of said spray range by said article to be sprayed.

References Cited UNITED STATES PATENTS 2,369,155 2/1945 Marinsky et al. 188-416 X 2,547,884 4/ 1951 Paasche 1182 2,906,214 9/1959 Frank 118-8 X 2,961,990 11/1960 Wruck 1188 X 2,971,492 2/ 1961 Enssle 1182 3,013,445 12/1961 Enssle 1182 X CHARLES A. WILLMUTH, Primary Examiner. J. P. MCINTOSH, Assistant Examiner.