US3290169A

US3290169A - Process and apparatus for electrostatic detearing

Info

Publication number: US3290169A
Application number: US222417A
Authority: US
Inventors: Jr John Sedlacsik
Original assignee: Interplanetary Res and Dev Corp
Current assignee: Interplanetary Res and Dev Corp
Priority date: 1962-09-10
Filing date: 1962-09-10
Publication date: 1966-12-06
Anticipated expiration: 1983-12-06

Description

Dec. 6, 1966 J. SEDLACSIK, JR

PROCESS AND APPARATUS FOR ELECTROSTATIC DETEARING Filed Sept. 10, 1962 2 Sheets-Sheet 1 SOLVENT L INVENTOR .rj JOHN SEDLACSIK JR.

ATTORNEY Dec. 6, 1966 J. SEDLACSIK, JR

PROCESS ANIAPPARATUS FOR ELECTROSTATIC DETEARING 2 Sheets-Sheet 2 Filed Sept. 10, 1962 I A V INVENTOR JOHN SEDLACSIK JR.

ATTORNEY United States Patent 1 3,290,169 PROCESS AND APPARATUS FOR ELECTRO- STATIC DETEARING John Sedlacsik, Jr., Garfield, N..I., assignor to Interplanetary Research 8: Development Corp., Garfield,

N.J., a corporation of New Jersey Filed Sept. 10, 1962, Ser. No. 222,417

. 18 Claims. (Cl. 11793.41)

This invention relates to an apparatus for coating articles in an electrostatic field wherein said articles are first dipped in a bath of coating material and then passed through an electrostatic field for removing excessive coating and tear drops, reference being had to Letters Patent No.1 2,359,476, granted on an application of Charles K. Gravley, October 3, 1944, entitled Electrostatic Method and Apparatus.

In the application of paint, liquid, oil or other coating materials by the dip process, the excess material which invariably remains at the drain-off point after substantial flow has ceased, has always been a problem which has seriously limited widespread application of this most efficient coating method. The accumulations which remain at the drain-off points are referred to as tears. In accordance with the above patent, a process and apparatus is disclosed which accomplishes the removal of this excess material and leaves the finish on the article smooth and complete. This removal is accomplished by so arranging the apparatus as to cause the dipped articles to pass at the correct time through an electrostatic field, wherein an electric force is applied to all parts of the article which tends to pull it towards a spaced electrode charged at high voltage. If the article is properly held and the excess coating material is sufficiently liquid, it will be pulled off the article, leaving a coating that is smooth and free from tear drops or similar excess material. This removal of excess material is herein referred to as detearing.

The present method and apparatus provides a novel electrode which need not be replaced at any time and which normally will clean itself. In one form of the invention, should an accumulation of paint or the like be had upon the electrode, it may be easily removed by wiping it therefrom without the necessity of replacing the entire electrode such as is the case when the same is made of expanded metal or the like.

Generally there is provided an electrode of circular structure which may be flat or conical or of any other suitable contour and which is centrally provided with means for supplying the surface thereof with a continuous or intermittent flow of a solvent. In one form of the invention, the electrode is coated with polytetrafiuoroethylene or the like so that paint or lacquer accumulating thereon may be easily wiped off. The electrode is provided with simple means for rotating the same so that as solvent is fed to the electrode and dissolves the paint and the like which may accumulate thereon, it is removed by centrifugal force and, in another form of the invention, it is assisted in such movement by a fan of novel structure so that at all times the electrode is substantially clear of accumulations. A tank is provided for collecting the liquid and means is provided for removing gases from such tank. Means is provided for draining the tank from time to time as may become necessary.

It is accordingly an object of the invention to provide, in an electrostatic coating apparatus of the character set forth, novel means and method for removing accumulations of paint or the like from an electrode forming a part of the invention.

Still another object of the invention is to provide, in an apparatus of the character set forth, a novel electrode.

A further object of the invention is to provide, in an 3,290,169 Patented Dec. 6, 1966 apparatus of the character set forth, a novel coating for an electrode forming a part of the invention.

A still further object of the invention is to provide a novel rotating electrode forming a part of the apparatus.

A still further object of the invention is to provide, in an apparatus of the character set forth, a novel fan forming a part of the invention.

Other and further objects of the invention will become apparent from a reading of the following specification taken in conjunction with the drawings, in which:

' FIGURE 1 is a fragmentary elevational view, partly broken away and partly schematic illustrating an endless conveyor and articles carried thereby to be treated in accordance with the present invention,

FIGURE 2 is a fragmentary vertical sectional view, partly in elevation and partly schematic, illustrating an apparatus in accordance with the present invention,

FIGURE 3 is a plan view, partly schematic, of the apparatus illustrated in FIGURE 2,

FIGURE 4 is an enlarged fragmentary vertical sectional view illustrating a modified form of electrode, and

FIGURE 5 is a view similar to FIGURE 4 but illustrating a still further modification the invention may assume.

Referring more particularly to the drawings, there is shown therein, in FIGURE l, a series of articles 10 mounted at the lower end of support members 11 carried in longitudinally spaced relation by an endless carrier indicated at 12 which carrier is electrically grounded, as indicated at 13.

In carrying out the invention, there is provided an elongated tank 14 having an open top 15 immediately over which the articles 10 are adapted to pass, as indicated in FIGURE 3. The tank is provided with one or more stations generally indicated at 16 which stations are longitudinally spaced from one another if more than one is provided. These stations are spaced at a distance to allow time for the coating material on the parts to sag to the edge prior to application of high voltage at the next station.

In the form of the invention illustrated in FIG. 2, the station 16 comprises a casing 17 extending from the bottom of the tank 14, the casing having a top 17a of insulating material, in which casing 17 upon base 18 there is mounted standard 19 of insulating material which protrudes upwardly through casing 17 and which is provided at its upper end with a metallic support 19a carrying air driven motor 20 connected by air pipe 21 of insulating material which extends downwardly through casing 17 to a conventional air pump 22. The motor 20 is adapted to rotate a shaft 23 atop which is affixed a fiat circular metallic electrode 24. The shaft is centrally provided with a longitudinal opening 25 which communicates at its upper end with an opening 26 in the plate-electrode 24. Fan blades 27 are radially alfixed to the underside of the plate 24.

A longitudinally extending opening 28 is provided in the support and communicates at its upper end with the opening 25 and at its lower end with a solvent supply pipe 29 of insulating material .which' extending downwardly through the casing 17 to a pump 30 which communicates by means of a pipe 31 with a tank of solvent 32. The pump 30, the solvent tank 32 and connecting lines therebetween are normally isolated from the ground depending upon the conductivity of the solvent being used or unless the tank is made of non-conductive material.

The support 19a which is of metallic construction, is connected by a wire 33 to a source of high voltage 34 which is grounded, as indicated M35. The wire 33 extends downwardly through the insulated top 17a of casing 17 from its connection, as indicated at 36, with the support 19a and it will be noted that the source of high voltage is at a point remote from'the tank 14.

In the event that two or more stations 16 are utilized in the apparatus, it will be apparent that a common source of high voltage may be utilized, as indicated at FIGURE 3.

To remove fumes which may accumulate above the tank 14, an exhaust pipe 37 having an exhaust fan 38 therein is provided for removing such fumes to a remote place.

When used liquid, indicated at 39, accumulates in the tank 14 it may be removed therefrom by means of a spigot 40 mounted in the lower portion of the tank 14.

In operation, it will be apparent that the disc-electrode 24 is adapted to be slowly rotated by means of the airmotor 20, the latter being supplied with compressed air to the pipe 21 through the pump 22. At the same time or from time to time if so desired, solvent is being pumped from the solvent tank 32 through the

pipes

31 and 29 by means of the pump 30 through the

passages

28 and 25 to the central opening 26 in the disc 24. As the solvent emerges through the opening 26 it will move outwardly upon the surface of the disc 24 dissolving any paint, lacquer or the like which may have been deposited thereon through the electrostatic forces above mentioned after which it will, through centrifugal force, move the thus dissolved paint or the like entirely from the disc 24 where it will fall by gravity into the lower portion of the tank 14 accumulating as indicated at 39. Whenever desired, this may be removed by means of the spigot 40. Meantime, fumes which may accumulate above the surface of the liquid solvent in the tank 14 may be removed continuously by means of the pipe 37 and exhaust pump 38.

It will be understood that as tears accumulate upon the lower end portions of the articles 10 by gravity that they will be drawn by the electrostatic field and attracted to the surface of the rotating disc 24 after which such accumulation is dissolved as heretofore described.

In a modified form of the invention as shown in FIG- URE 4, the upper surface of the disc 24 is provided with a coating 41 of tefion or the like. In this case, whenever particles have accumulated upon the upper surface of the disc 24 and have not been removed through the combined action of the solvent and centrifugal forces as above described, the remaining accumulation upon the disc 24 may be removed merely by wiping the upper surface of the teflon coating since the coating material will not adhere thereto.

In FIGURE there is shown a further modification the invention may assume. In this case, instead of the flat disc structure shown in FIGURES 2 to 4, inclusive, there is provided a generally conical electrode 42 terminating in a neck 43 at its lower end. In this case the opening 28 in the standard 19 communicates at its upper end with a tube 44 the upper end of which is bent, as indicated at 45, to terminate in close proximity to the interior surface of the member 42. If desired, and as shown, the interior surface of the member 42 may be coated with teflon, as indicated at 46, for the same purposes as above described with reference to the coating 41 illustrated in FIGURE 4. Again with reference to the showing in FIGURE 5, it will be apparent that solvent is pumped through the tube or nozzle 44 and deposited upon the interior of the member 42 whereupon it will rise and flow toward the upper periphery of the member 42 by centrifugal forces and thereafter discharge therefrom into the tank 14 likewise by such forces thus dissolving particles of paint which have been deposited thereon by the aforesaid electrostatic forces in the same manner as above described with reference to the showing, for example, in FIGURES 2 and 4.

Referring again to FIGURE 5, the tube 42 may terminate as indicated in dotted lines at 45a near the upper periphery of the innner surface of the electrode 42 in which case the electrode will be moved at a low rate of speed to allow the solvent to travel downwardly over the inner face of the electrode thus cleaning the same after which it will drop by gravity through the open lower end of the electrode into the tank 14. Alternatively or in conjunction with the tube 45a a tube may be positioned as indicated in dotted lines at 45b to direct a flow of solvent against the upper portion of the outer surface of the electrode to thus flow downwardly on the outer face of the same as it slowly revolves to thus maintain the outer surface or, if used in conjunction with a tube as at 45a, to clean both surfaces of the electrode 42.

It will be understood that the

electrodes

24 and 42 will be rotated at a speed sufiicient to remove any material which may have been deposited thereon. It will also be seen that the fan blades 27 will assist in moving matter discharged from the electrodes away from the standard 19 and its associated parts. It is also contemplated that the solvent may be fed periodically or continuously as desired and that the electrodes likewise may remain stationary for predetermined periods of time if so desired. The electrodes may be made of conductive or semi-conductive materials, may be directly or indirectly charged and may be provided with ribbed or corrugated as well as smooth surfaces.

It will also be apparent that the motor 20 may be repeatedly reversed by conventional means to thus cause the

electrode

24 or 42, as the case may be, to oscilate continuously or periodically.

It is to be understood that the

electrodes

24 or 42 may be charged by direct contact with the high voltage source 34 or may be indirectly charged by a grid or any suitable remote charging means.

While but certain forms of the invention have been shown and described herein, it will be readily apparent to those skilled in the art that many minor modifications may be made without departing from the spirit of the invention or the scope of the appended claims.

What is claimed is:

1. The method of detearing paint and the like from freshly coated articles comprising providing an electrode adjacent said articles, establishing an electrostatic field between said articles and said electrode of sufficient intensity to remove excess paint from said articles and deposit said excess paint on said electrode, periodically feeding solvent to the central portion of said electrode, and periodically moving said electrode sufiiciently to distribute said solvent over the surface thereof whereby to dissolve and remove coating electrostatically deposited from said articles upon said electrode.

2. The method of detearing paint and the like from freshly coated articles comprising providing a plurality of electrodes adjacent said articles, establishing an electrostatic field between said articles and said electrodes, periodically feeding solvent to the central portions of said electrodes, and rotating said electrodes to distribute said solvent over the surfaces thereof whereby to dissolve and remove coating electrostatically deposited from said articles upon said electrodes.

3. The method of detearing liquid from objects comprising positioning an electrode adjacent said articles, electrostatically charging said electrode, periodically supplying solvent to the surface of said electrode, and intermittently rotating said electrode to remove liquid electrostatically deposited thereon.

4. The method of detearing liquid from objects comprising positioning an electrode adjacent said articles, electrostatically charging said electrode, periodically supplying solvent to the surface of said electrode, and intermittently oscillating said electrode to remove liquid electrostatically deposited thereon.

5. Apparatus for removal of excess coating material from articles, said apparatus comprising an open tank,

means for suspending freshly-coated articles over said.

tank, an electrostatic detearing station mounted in said tank immediately below said articles, said station including a standard mounted in said tank, a vertical shaft rotatably mounted in said standard, a motor mounted on said standard for rotating said shaft, a circular electrode mounted atop said shaft, with a collecting surface thereof facing said articles, said electrode and said shaft having central communicating openings therein, and means for feeding solvent through said openings, to the collecting surface of said electrode.

6. Apparatus as defined in claim 5 wherein the electrode is disc-shaped.

7. Apparatus as defined in claim 5 wherein the electrode is disc-shaped and has fan blades aflixed to the bottom side thereof.

8. Apparatus as defined in claim 5 wherein the electrode has a coating of polytetrafiuoroethylene on at least the upper surface thereof.

9. Apparatus as defined in claim 5 wherein said electrode is conical.

10. Apparatus for the removal of excess coating material from articles, said apparatus comprising an opentopped tank, means for suspending freshly coated articles over said tank, an electrostatic detearing station mounted in said tank immediately below said articles, said detearing station including a detearing electrode, means for creating an electrostatic field between said electrode and said articles for the attraction of excess coating material on said articles to said electrode, and drive means for moving said electrode with sufiicient force to fling from said electrode coating material attracted thereto from said articles.

11. Apparatus as defined in claim wherein said electrode has a coating of polytetrafiuoroethylene.

12. Apparatus for the removal of excess coating material from articles, said apparatus comprising an opentopped tank, means for conveying freshly coated articles over said tank, an electrostatic detearing station mounted in said tank immediately below said articles, said detearing station including a detearing electrode, means for creating an electrostatic field between said electrode and said articles for the attraction of excess coating material on said articles to said electrode, and drive means for rota-ting said electrode with sufiicient force to fling from said electrode coating material attracted thereto from said articles.

13. Apparatus for the removal of excess coating material from articles, said apparatus comprising an opentopped tank, means for conveying freshly coated articles over said tank, a plurality of electrostatic detearing stations mounted in said tank immediately below said articles, said detearing stations each including a detearing electrode, means for creating an electrostatic field between said electrodes and said articles for the attraction of excess coating material on said articles to said electrodes, and drive means for rotating said electrodes with sufiicient force to fling from said electrodes coating material attracted thereto from said articles.

14. Apparatus for the removal of excess coating material from articles, said apparatus comprising an opentopped tank, means for suspending freshly coated articles over said tank, an electrostatic detearing station mounted in said tank immediately below said articles, said detearing station including a detearing electrode, means for creating an electrostatic field between said electrode and said articles for the attraction of excess coating material on said articles to said electrode, and coating removing means associated with said detearing station for removing from said electrode coating material electrostatically attracted onto said electrode from said articles, said coating removing means including a motor mounted Within said tank, a vertical shaft operatively coupled to said motor for rotation thereby, and means mounting said electrode on said shaft for rotation of said electrode at a rate sufiicient to fling therefrom into said tank coating material electrostatically attracted to said electrode from said articles.

15. Apparatus as defined in claim 14 wherein said electrode is coated with polyfluoroethylene.

16. Apparatus as defined in claim 14 wherein said electrode is hollow and circular in horizontal crosssection 17. Apparatus as defined in claim 14 wherein said electrode is disc-shaped.

18. Apparatus as defined in claim 17 wherein said electrode has a fan blade aflixed to the bottom side thereof.

References Cited by the Examiner UNITED STATES PATENTS 2,359,476 1/ 1940 Gravley 117-93 .41 2,444,144 6/ 1948 Ransburg. 2,945,472 1/1956 Gengenbach et al.

117-93.41 X 3,128,201 4/ 1964 Gauthier 118-628 X ALFRED L. LEAVITT, Primary Examiner.

RICHARD 1?. NEVIUS, A. GOLIAN,

atssisrqnt Examiners,

Claims

1. THE METHHOD OF DETEARING PAINT AND THE LIKE FROM FRESHLY COATED ARTICLES COMPRISING PRROVIDING AN ELECTRODE ADJACENT SAID ARTICLES, ESTABLISHING AN ELECTROSTATIC FIELD BETWEEN SAID ARTICLES AND SAID ELECTRODE OF SUFFICIENT INTENSITY TO REMOVE EXCESS PAINT FROM SAID ARTICLES AND DEPOSIT SAID EXCESS PAINT ON SAID ELECTRODE, PERIODICALLY FEEDING SOLVENT TO THE CENTRAL PORTION OF SAID ELECTRODE, AND PERIODICALLY MOVING SAID ELECTRODE SUFFICIENTLY TO DISTRIBUTE SAID SOLVENT OVER THE SURFACE THEREOF WHEREBY TO DISSOLVE AND REMOVE COATING ELECTROSTATICALLY DEPOSITED FROM SAID ARTICLES UPON SAID ELECTRODE.