US3405679A - Spray unit for use with arcuate conveyor paths - Google Patents

Description

Oct. 15, 1968 o. NORRIS ETAL 3,405,679

SPRAY UNIT FOR USE WITH ARCUATE CONVEYOR PATHS Filed Nov. 16, 1966 2 Sheets-Sheet 1 INVENTORS EDWARD O. NORRIS RICHARD F WIGGINS BY (J g f ATTOR N EY Oct. 15, 1968 E. o. NORRIS ETAL 3,405,679

SPRAY UNIT FOR USE WITH ARCUATEJ CONVEYOR PATHS 2 Sheets-Sheet 2 Filed Nov.

FIG. 2

4 2 2 5 Mm 2 H 8 m I w W H w =1 4 ,AL 3 HHHHM HHHHH l 2(3 1 1| I 1 F\ Maw/ i u 7 M 3 I \\l 4% A a 2 V \\I 9 I x 7 I g ATTORN S United States Patent 3,405,679 SPRAY UNIT FOR USE WITH ARCUATE CONVEYOR PATHS Edward O. Norris, Westport, and Richard F. Wiggins, Fairfield, 'Conn. (both The Gyromat Corporation, P.O. Box 4157, Bridgeport, Conn. 06607) Filed Nov. 16, 1966, Ser. No. 594,808 7 Claims. (Cl. 118-2) ABSTRACT OF THE DISCLOSURE The present disclosure relates to industrial spray installations and is directed particularly to new arrangements for consecutively applying coatings to articles traveling along a curved conveyor loop.

Summary of invention It has been known to the art to employ a continuously rotating electrostatic spray disk which provides a single, generally annular spray pattern, emanating from a single source, in association with a circular or substantially circular conveyor path. However, such arrangements are not suit-able for applying diverse coatings to an article traversing the conveyor loop and have had certain shortcomings in spray deposition efiiiciencies. Accordingly, the present invention is directed to improve and highly efficient spraying arrangements of pneumatic spray guns especially adapted for use in association with circular conveyor paths.

Specifically, the present invention employs a new spray) head including a plurality of spray guns which are adapted to focus a series of discrete fan sprays, emanating from plural sources, on segments or bands of the circular conveyor path, rather than providing a single, endless or continuous spray through a full 360, as is the case with the aforementioned rotating disk-type spray devices. More specifically, and in accordance with an important aspect of the present invention, individual and discrete spray zones are established by pairs of guns which are aligned with predetermined chords of the circular conveyor path. In accordance with the invention, each of thes pray guns, representing a distinct source, establishes a separate spray zone or cloud of coating material through which a part to be coated is conveyed.

Thus, each gun of a gun pair is oppositely oriented with respect to the direction of movement of a nonrotatably suspended part entering its zone. In other words, one of the guns of a pair will be generally directed toward the leading surfaces of a part conveyed therepast, while the other gun of the pair will be generally directed toward the trailing surfaces of the part. This arrangement tends to assure uniformity and completeness of the applied coating in accordance with the invention.

As a further aspect of the invention and as a means of increasing the efficiency of coating deposition, the individual spray guns of the new spray head are independently actuatable and are arranged to operate only in the presence of an article to be coated. Thus, for example, when a single part to be coated is conducted around the circular loop, each of the guns may be operated successively in a manner whereby a series of discrete sprays tends to follow the part in a highly efficient manner, rather than in a comparatively inefficient manner of deposition occasioned by the part tending to follow a continuous, circular spray when a rotating disk-type spray source or its equivalent is used.

The spray deposition unit of the present invention may be operated either electrostatically or non-electrostatically, as desired or found necessary, and may be readily r 4 3,405,679 Ice Patented Oct. 15, 1968 installed in any established loop to convert it into an efiicient spray station having the above-mentioned ad vantages.

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

FIG. 1 is a plan view of a new and improved spray station embodying the principles of the invention;

FIG. 2 is a fragmentary, cross-sectional view of FIG. 1 taken along line 22 thereof; and

FIG. 3 is a side elevational view of a spray gun having a particularly advantageous nozzle arrangement which may be employed in the practice of the present invention.

Referring now to FIGS. 1 and 2, a new spray head assembly 9 is adapted to be centrally disposed within any existing or previously installed conveyor system 10 arranged in a generally circular loop 11 to form an improved spray station. As will be understood, the conveyor loop 11 need not be completely closed or completely circular. It may be semicircular, arcuate, or otherwise looped in configuration, as long as its shape is such that articles traveling thereabout will successively pass the plural guns of the spray head 9.

A series of hanger elements 12 are operatively associated with the conveyor 10 and are adapted to be moved thereabout by a suitable drive mechanism (not shown). If desired, the hanger elements may be of the rotatable type often employed in coating operations. As shown in FIG. 2, a plurality of articles A which are to be coated in the new spray station are suspended from the hanger elements 12 at an entrance station 13 and are removed from the conveyor at an exit station 14 after they have been coated by the new spray assembly 9.

In accordance with the invention, the spray assembly includes a central stanchion 15 which is installed at the geometric center of the loop 11 and which is fixedly supported in a vertical position by a mounting bracket 16. A spray gun supporting platform 17 including a sleeve 18, is reciprocable for a predetermined stroke along substantially the full length of the stanchion 15. As shown, the platform 17 is directly connected by a bracket 26 to a pneumatic reciprocating apparatus 27.

In accordance with the invention and as shown best in FIG. 1, two electrostatic spray guns 19 and 20 are aligned oppositely along a chord of the circular loop 11, and two more electrostatic spray guns 21, 22 are similarly aligned along another chord of the circular loop. The second chord is radially offset from the center stanchion 15 by a distance equal to the radial offset of the first pair of spray guns and is generally parallel to the first mentioned chord. As should be understood, each of the guns 19 through 22 is adapted to issue a discrete fan spray pattern and to establish a spray zone, the spray particles of which will be applied to the articles A as they are conveyed therethrough. In accordance with the invention, a non-rotatably suspended article which has successively traversed the zones of each of the guns will have received a balanced and uniform coating, since the asymmetries of any one zone of a gun with respect to the loop are balanced by the asymmetries of the gun with which it is paired.

The spray guns 1922 may be of any standard pneumatic type suitable for electrostatic spraying operation. For eX- ample, the spray guns may be conventional high or low pressure air guns suitably modified to be operated electrostatically. However, superior performance, in the practice of the present invention, has been obtained by employing spray guns utilizing low atomizing pressures and low velocity particle sprays of which the single nozzle guns 19-22, shown in FIGS. 1 and 2, are typical. Alternatively, a low pressure, double nozzle gun 23 such as illustrated 3 in FIG. 3 and described in detail in United States Patent No. 3,219,276, may be employed to advantage. It should be noted that pressure regulators 24 for each of the guns 19-22 are supported directly on the platform 17 in order that the elevation of the gun with respect thereto is uniform at all times. A detailed description of this aspect of the operation of the spray guns as well as a more detailed description of the structure of the single nozzle guns may be had by referring to copending U.S. application Ser. No. 340,466, filed J an. 27, 1964, now U.S. Patent No. 3,344,992.

In accordance with an important aspect of the invention, each spray gun 19-22 is independently supplied with a coating medium through an appropriate supply line 25, and, therefore, each gun constitutes an individual source with respect to the loop 11. Of course, the plural supply lines themselves may be connected to a common supply of coating medium or separate supplies. Accordingly, when desired or found necessary, each zone may be comprised of particles of a different coating composition.

Advantageously, the nozzles of the guns are pulsingly operated by momentarily shutting them off at the end of each stroke or half stroke of the reciprocating platform 17. This type of pulsing operation of the guns tends to keep the nozzles clear and tends to maintain substantially consistent spray rates in each of the zones.

As a further important aspect of the invention, suitable automatic sensing and control devices, such as photocell controls 36, 37 are associated with each of the guns 19-22. The photocell controls 36 are mounted adjacent the loop 11 and are used to detect the presence of an article to be coated and to control the guns accordingly. As will be understood, each photocell control 36 is appropriately connected to a spray gun to prevent the gun from operating when an article is absent from the conveyor, i.e., when an empty hanger 12 approaches a spray zone. For example, if a single article were to be conveyed about the loop or if the end of a series of articles were to be reached, the guns 19-22 would be sequentially and automatically shut off by the photocell controls 36 as the single article (or last article) traversed the loop. This, of course, prevents the Waste of coating materials and increases the efiiciency of the new spray assembly.

The photocell controls 37 are mounted on the reciprocating sleeve 18 in association with each spray gun and act to stop the spray of a nozzle when the lower edge of an article has been detected. Thus, when the relatively short articles A are being coated, the photocell control 37 will terminate the spray before the stroke of the reciprocating platform 17 is completed. However, when a relatively long article B is to be coated, the gun will be operated and spray issued therefrom for substantially the entire stroke. For example, under the control of the photocell controls 37, a long article may directly follow a short article around the conveyor loop 11, or vice versa, and the spray durations for each of the guns on the platform will automatically adjust for the change of size. This type of carefully controlled operation further increases the spraying efiiciency of the new and improved spray station, as will be appreciated.

It should be understood that the specific coating apparatus 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. For example, in coating applications where only extremely short articles are to be coated, the sleeve 18 may be fixed to the stanchion 15, and the new unit may be operated in a non-reciprocating manner. Accordingly, reference should be made to the following appended claims in determining the full scope of the invention.

What is claimed is:

1. In a spray station including a generally circular portion of a conveyor loop disposed in a predetermined plane, an improved spray unit comprising (a) a first pneumatic nozzle means disposed interiorly of said circular loop portion in a plane parallel with the plane of said loop portion and aligned with a first predetermined chord thereof;

(b) a second pneumatic nozzle means disposed interiorly of said circular loop portion in a plane parallel with the plane of said loop portion and aligned with a second predetermined chord thereof;

(c) one of said pneumatic nozzle means being linearly oriented with respect to said loop to concentrate a discrete spray pattern upon the leading surfaces of an article traveling around said loop and through said pattern in a predetermined direction;

(d) the other of said pneumatic nozzle means being linearly oriented with respect to said loop to concentrate a discrete spray pattern upon the trailing surfaces of an article traveling around said loop and through said pattern in a predetermined direction;

(e) supply means adapted to deliver spray media to said pneumatic nozzle means;

(f) control means operable to actuate said pneumatic nozzle means only in the presence of an article to be coated; and

(g) support means maintaining said pneumatic nozzle means in said predetermined orientations with said loop.

2. A spray unit in accordance with claim 1, in which (a) said first and second chords are coextensive and said first and second nozzle means are oppositely aligned therealong in a common plane.

3. A spray unit in accordance with claim 1, which includes (a) means reciprocating said nozzles along axes perpendicular to the plane of said conveyor loop.

4. A spray unit in accordance with claim 1, in which (a) said supply means includes means delivering a difierent spray medium to each of said first and second nozzle means.

5. A spray unit in accordance with claim 1, in which (a) said first and second chords are parallel.

6. A spray unit in accordance with claim 1, which includes (a) a plurality of first and second nozzle means.

7. A spray unit in accordance with claim 1, in which (a) said nozzle means includes means for flattening a spray in a plane generally parallel to the plane of said loop.

References Cited UNITED STATES PATENTS 4/1954 Peeps 1l8324 X 7/1959 Sedlacsik l183 14 X

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