US2800418A - Method and apparatus for applying coating material - Google Patents

Description

July 23, 1957 L. J. CANNON v METHOD AND APPARATUS FOR APPLYING COATIG-MATERIAL Filed Oct. 15. 1956 I k lg 4.4

5 T 63 AZ 44- ,6 a 4/ Veni' Tube INVENTbR. Lloyd J. Cannon Attorne METHOD AND APPARATUS FOR APPLYING COATING MATERIAL Lloyd J. Cannon, Brea, Calif. Application October 15, 1956, Serial No. 616,062 9 Claims. (Cl. 117-42) This invention relates to the method and apparatus for applying coating material in stripes or lines to a moving surface and comprehends means for controlling the supply of the coating material to a distributing point wherein the supply is under extremely accurate control so that there will always be suificient coating material, but at no time a flooding of the surface being coated.

Generally the object of the invention is the provision of means for establishing equilibrium of forces between the point of distribution of the coating fluid and the point of supply, the point of distribution being directly associated with the weight of a short column of coating fluid plus capillary forces, while the supply is associated with the weight of a longer column of coating fluid.

Another object of the invention is to maintain the balance between a capillary feed and a syphonic action, whereby the flow of coating fluid through the bore of the apparatus will be maintained at an appropriate pressure for the coating operation, this balance being produced by variation of the capillary feed as through a variation in the bore of a tube delivering the coating material.

More specifically the invention comprehends the use of a syphon formed of a flexible non-elastic stretchable tube, the short leg of the syphon forming the delivery end of the coating material while the longer leg of the syphon is connected with a supply, the supply being variable in elevation with respect to the point of discharge and the tube being stretchable for modifying the capillary action of the fluid in the tube.

These and other objects of the invention will more clearly appear by reference to the accompanying drawings forming a part of the instant application, wherein like characters of reference designate corresponding parts throughout the several views, in which:

Fig. 1 is a perspective view of an apparatus embodying the invention;

Fig. 2 is an enlarged vertical section through the tube stretching device;

Fig. 3 is a section on line 3-3 of Fig. 2; and

Fig. 4 is a diagrammatic illustration showing the theory of operation.

In the present disclosure a standard is illustrated embodying a pair of telescopic sections 1 and 2, section 1 being provided with a slot 3 which is associated with a bolt 4- having the thumb nut 5 whereby the two sections may be relatively adjustable for elevating or lowering the horizontal table 5. The table 5 projects laterally of each side of the standard and on one side supports a tray 6 in which is located a plurality of receptacles 7, each of which is vertically adjustable by means of a threaded screw 8 which is threaded through the table 5 and has an enlarged end 9 which encases the bottom of a receptacle 7 for elevating or lowering the same. It will be understood that there will be provided a separate screw adjustment 8 for each of the receptacles so that they can be separately regulated to control the fluid elevation to each of the discharge points, there being as many discharge points as 2,800,418 Patented July 23, 1957 desired to produce a required pattern on the traveling sheet S.

Each of the fluid receptacles 7 is provided with a closure cap 10 to provide an appropriate seal and this cap is vented through pipe 11 having downturned end 12 and vent 14. The level of fluid in the receptacle is indicated at 15 and submerged in the fluid is the long leg 16 of a syphon structure formed from a stretchable, non-elastic plastic of any desired type and preferably transparent whereby the passage of fluid therethrough may be inspected. The base of the syphon is shown at 16 with the short discharge end 17 and an outlet 18, the latter being in approximate contact with the traveling sheet S. The short discharge end of each of the syphon tubes is separately supported by a suitable bracket having a base 20 secured by screws 21 to the top plate or table 5 of the support. The brackets each comprise a vertical tube 22 in which there is a rod 23 secured in adjusted position by thumb screw 24. The adjustable rods 23 are each provided with clamps 25 which extend laterally from the upper portion thereof and clamp the short discharge legs of the syphon tubes as shown at 26. By this construction the position of the discharge end 18 may be adjusted with respect to the coating material in the receptacle 7 and also with respect to the traveling sheet S which may be of any form or could be in the form of a plate or disk, it being only necessary that the sheet have a suitable movement for providing for the application of the coating material thereto from the discharge end 18.

In the present disclosure means are shown for stretching a portion of the base 16 of the syphon tubes, this means including a transverse channel 30 supported on the T-head 31 of the upright panel 32, the latter being mounted on the table or platform 5 by the lateral flanges 33 and secured thereto by screws 34 as shown. In the channel 30 are the blocks 35 having lateral foot extensions 36 extending into the channels 37 permitting these blocks to be laterally adjusted or spaced. The tops of the blocks 35 have lateral wings 41 and medial semicircular recesses 42 for seating a portion of the base 16 of the syphon structure. Clamp plates having medial semi-circular transverse portions 42 and wings 43 are provided for association with the heads 35 and clamps 44 complete the assembly and permit the clamping of the base of the tube at a pair of spaced points.

The tops 42 of the blocks 35 are provided with vanes 50 having aligned threaded openings 51 through which the turnbuckle structure 52 is threaded, the turnbuckle being provided with thumb screw 53 whereby rotation of the thumb screw 53 will cause movement of the clamp blocks to stretch the intermediate section 16 of the base 16 of the syphon tube to reduce the diameter of the nonelastic stretchable tube for reducing the bore for modifying the capillary efficiency of the tube. By reference to Fig. 2 it will be noted that the clamp blocks for the adjusting means for the tube includes soft metal inserts 55 which are threaded into the tube bodies at 56 to provide a firm grip on the tube structure during stretching operation. Any suitable means might be provided to secure a suitable engagement between these parts to permit a gripping of the tube for the stretching operation.

By the proposed structure the coating apparatus contemplates a multiplicity of associated adjustments for securing exact control of the flow of fluid as well as an appropriate location for the discharge end of the syphon tube onto the traveling surface. The discharge end 18 of the syphon tube can be adjusted through the standards 2223 and associated with these discharge ends is the adjustment 8 for the individual receptacles containing the coating material. The modification of the legs of the syphon will basically determine the flow, this flow in turn being regulated by the capillary efficiency of the tube and this capillary efliciency of the tube in turn is modified by the diameter of the tube as regulated by the stretching of the base of the tube. In fact the tube could be stretched at any point throughout its length with or without the stretching mechanism shown, it being apparent to one skilled in the art that a manual stretching of the tube by an operator who is familiarwith the apparatus could readily function to produce the desired results in the matter of flow. The elimination of the stretching means shown in 2 would also permit a more flexible manipulation of the tube in instances where the tube would necessarily have to be threaded through intricate mechanism.

A brief discussion of the type of computation which would be used to arrive at the elevation ditferential pro duced by a capillary tube will follow. In following this discussion, it must be remembered that capillarity is a result of surface tension; hence occurs only where fluid surface is in contact with air and bounded by a solid wall. In the illustration of Fig. 4 pick a point A midway between discharge point P and point B which is at the same elevation as point P. When the system is in equilibrium the forces on each side of point A must be equal. To the left, we have the weight of the fluid plus the capillary force; while on the right is the weight of a longer column of fluid. As an approximate method of computing the maximum elevation differential available, we can cancel out the two equal lengths of fluid columns and equate the capillary force to weight of the column of fluid it can lift. The capillary force is given by F='1rdT cos B which is the circumference of the discharge bore multiplied by the axial component of the surface tension, T cos ,3. This force must equal the weight of the column of fluid which is computed by multiplying its volume by its density. Our force equation thenbecomes Then dividing through by 1r and rearranging terms, we get where h=elevation differential (inches) T=surface tension of ink B=angle of contact between discharge bore and edge of meniscus w=density of the fluid d=I. D. of discharge bore D=I. D. of plastic tubing Now we must assume some values for w, T, p, etc. d will be .008 and D will be .026". In order to simplify number picking, we can use data for water for w and T. This gives us a w value of about .0361 lb./in. and T is .00499 lb./ft. or .000416 lb./in; In order to carry out the arithmetic, let us assume a value of 45 for the angle ,9; thus cos 5:.707.

We may now compute h:

4X.008X.004l6 .707 .03e1 .020 .02e

At first glance this number looks quite low, so we must now examine the discharge point. A simplified sketch of a discharge point against a sheet is shown in Fig. 1. Here the fluid has wet the sheet, filled in the space between the discharge point and sheet, and formed a new meniscus at the discharge point. It can readily be seen that the new meniscus has a smaller surface area. In fact, as a perfectly sealed contact between the discharge point and the sheet is approached, the surface area of the fluid in contact with air approaches zero. This means that an equivalent diameter for this surface would also approach zero. As shown by the equation for capillary force, it must become larger as the meniscus diameter, or area, becomes smaller. This must determine the elevation differentials up to 4 or 5 inches. It is also apparent that discharge point design, fluid and sheet surface each exert considerable influence on the elevation differential available by the calculations.

The discussion of the suggested formulae is, of course, basic and is subject to numerous variables but having the facts in mind it will be obvious that the instant comprehension of using the transparent non-elastic stretchable tube for reducing the cross sectional area of the capillary feed dominates the controls. There is also the fact that this syphon tube is preferably transparent whereby air bubbles which might occur during the transfer of fluid would be visible and could readily be eliminated by squeezing operation of the tube from a point to one side of an air bubble to one extremity. In other words, should an air bubble interfere with the normal feeding of the fluid, this factor would be recognized at a glance by the operator and could be eliminated without the necessity of repair or interchange of parts and simply through a squeezing of the tube. Obviously the elimination of the air bubble would not be a matter of guess but could be accurately observed through the transparent plastic tube.

By the invention shown and described, means have been provided for accurately and minutely controlling and regulating the discharge of fluid through a syphon for the purpose of striping or marking a moving surface.

What I claim is:

1. In an apparatus for applying a line of dye fluid to a traveling sheet, a supporting structure, a sealed receptacle having a vent, a syphon tube of flexible transparent stretchable material having its long leg submerged in the fluid in the receptacle and its other leg having a terminal discharge portion in contact with the traveling sheet, said tube including a portion of a dimension to provide capillary attraction for the fluid passing through the tube from the fluid receptacle, means for holding the discharge end of the tube in contact with the traveling sheet, means for adjustably supporting the fluid receptacle, and means for stretching the tube for a portion of its length to reduce its diameter for modifying the capillary efliciency of the tube and stabilize the flow of fluid therethrough from the receptacle to the terminal discharge to limit the supply of fluid to an amount only sufficient to form a line on the traveling sheet.

2. The structure of claim 1 characterized in that the supporting structure includes vertically adjustable members for supporting and adjusting a plurality of receptacles.

3. The structure of claim 1 characterized in that the supporting structure includes means for supporting and adjusting the position of a plurality of terminal discharge portions.

4. The structure of claim 1 characterized in that the supporting structure includes a platform upon which is mounted a pair of laterally adjustable clamps for stretching the tubing.

5. In an apparatus for applying a line of dye fluid to a traveling sheet, a supporting structure, said supporting structure including a base having a pair of laterally extending wing portions and a vertically extending panel, a platform at the top of said panel, a plurality of fluid containing receptacles mounted on one of said Wings, means for vertically adjusting the receptacles with respect to said wings, a plurality of vertically adjustable clamps supported on said other wing, a plurality of flexible transparent non-stretchable syphon tubes, said syphons each having one leg terminating in the fluid in said receptacles and the other leg having its terminal discharge portion supported by said clamps in contact with a traveling sheet whereby the fluid from said receptacle is transferred by said syphons to said sheet, said syphons being stretchable for restricting the capillary bore in said tubes for modifying the discharge of fluid therethrough.

6. The structure of claim 5 characterized in that means are provided for stretching the tube for reducing the capillary bore therein, said means including a channel guideway extending transversely across the top of said panel, a pair of spaced clamps carried in said channel and adapted to engage said tube at spaced points, and means for relatively moving said clamps.

7. The structure of claim 5 characterized in that means are provided for stretching the tube for reducing the capillary bore therein, said means including a channel guideway extending transversely across the top of said panel, a pair of spaced clamps carried in said channel and adapted to engage said tube at spaced points, and oppositely threaded means engaging said clamps for causing their relative movement.

8. The method of applying a line of dye to a moving sheet, said method consisting in supplying fluid through a transparent stretchable non-elastic syphon, providing a supply of fluid for said syphon, varying the relative height of the fluid with respect to the discharge end of the syphon to provide substantially the correct amount of fluid for discharge onto the sheet, and stretching the syphon tube to modify the capillary attraction of the tube to further regulate the flow of fluid through the syphon.

9. In a method of feeding coating fluid through a syphon which consists in providing a syphon of transparent flexible non-elastic stretchable material having such a diameter as to facilitate capillary attraction, submerging the long end of the syphon in fluid, applying the discharge end of the other end against a moving body to which the fluid is to be applied, adjusting the elevation of the fluid to generally regulate the syphon discharge and stretching the syphon tube to vary the capillary bore therein to modify the syphonic action.

No references cited.

Claims (1)

1. IN AN APPARATUS FOR APPLYING A LINE OF DYE FLUID TO A TRAVELING SHEET, A SUPPORTING STRUCTURE, A SEALED RECEPTACLE HAVING A VENT, A SYPHON TUBE OF FLEXIBLE TRANSPARENT STRETCHABLE MATERIAL HAVINFG ITS LONG LEG SUBMERGED IN THE FLUID IN THE RECEPTACLE AND ITS OTHER LEG HAVING A TERNINAL DISCHARGE PORTION IN CONTACT WITH THE TRAVELING SHEET, SAID TUBE INCLUDING A PORTION OF A DIMENSION TO PROVIDE CAPILLARY ATTRACTION FOR THE FLUID PASSING THROUGH THE TUBE FROM THE FLUID RECEPTACLE, MEANS FOR HOLDING THE DISCHARGE END OF THE TUBE IN CONTACT WITH THE TRAVELING SHEET, MEANS FOR ADJUSTABLY SUPPORTING THE FLUID RECEPTACLE, AND MEANS FOR STRETCHING THE TUBE FOR A PORTION OF ITS LENGTH TO REDUCE ITS DIAMETER FOR MODIFYUNG THE CAPILLARY EFFICIENCY OF THE TUBE AND STABILIZE THE FLOW OF FLUID THERETHROUGH FROM THE RECEPTACLE TO THE TERMINAL DISCHARGE TO LIMIT THE SUPPLY OF FLUID TO AN AMOUNT ONLY SUFFICIENT TO FORM A LINE ON THE TRAVELING SHEET.

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