US3177847A

US3177847A - Apparatus for applying organic liquid coating to moving strip material

Info

Publication number: US3177847A
Application number: US141891A
Authority: US
Inventors: Joseph E Schnierlein
Original assignee: National Steel Corp
Current assignee: National Steel Corp
Priority date: 1961-09-29
Filing date: 1961-09-29
Publication date: 1965-04-13
Anticipated expiration: 1982-04-13

Description

April 13, 1955 J. E. SCHNIERLEIN 3,177,847

APPARATUS FOR APPLYING ORGANIC LIQUID COATING TO MOVING STRIP MATERIAL Filed Sept. 29. 1961 INVENTOR.

JOSEPH E. SCHNIERLEIN i 25 BY. izo 26 W L ATTORNEYS United States Patent O 3,177,847 APPARATUS FOR APPLYING ORGANIC LIQUFD COATING T MUVING STRIP MATERIAL Joseph E. Schnierlein, Allentown, Pa., assignor to National Steel Corporation, a corporation of Delaware Filed Sept. 29, 1961, Ser. No. 141,391

' 3 Claims. (Cl. 118407) This invention relates to coating apparatus and more particularly to apparatus for applying organic coatings to continuously moving strip material.

Apparatus has been provided in the past for applying organic coating such as paints and enamels to surfaces of continuously moving strip material. However, it has not been possible with such apparatus to obtain extremely smooth coating of uniform controllable thickness especially when the surface of the strip material is irregular or when the strip material is of substantial width.

It is an object of the present invention to provide novel apparatus which makes it possible to apply extremely smooth organic coating of uniform thickness to continuously moving strip material and overcome the limitations of the prior apparatus.

The foregoing is accomplished by the provision of a novel arrangement for applying liquid coating substance to moving strip material. The novel arrangement includes a polished cylindrical roll positioned in line contact with the moving strip material and rotated in a direction opposite to the direction of movement of the strip material, together with means for applying measured quantities of liquid coating substance to the roll so as to form precisionally a pool of liquid coating substance extending trans versely of the strip material between the opposing surfaces of the strip material and the roller above the line contact. This arrangement provides liquid application of the coating substance to the strip material by action of the coating substance itself as distinguished from the use of mechanical means for applying or leveling the coating substance, and results in extremely smooth coatings irrespective of irregularities in the surfaces of the strip ma terial while making it possible to control the thickness of the coating to a degree and with uniformity heretofore unobtainable.

Other objects and features of the present invention will appear more fully from the following detailed description considered in connection with the accompanying drawing which illustrates one embodiment of the invention.

In the drawing, in which similar refe ence characters denote similar elements through the several views:

FIGURE 1 is a diagrammatic presentation of a strip coating line embodying principles of the present invention;

FIGURE 2 is a diagrammatic showing of a coating applicator constructed in accordance with the principles of the present invention;

FIGURE 3 is an elevational view, partly in section, of the coating applicator provided by the present invention, and

FIGURE 4 is a detailed view of a portion of the coating applicator shown in FIGURE 3.

With reference more particularly to FIGURE 1 of the drawings, a coating line for applying organic coatings to moving strip material is diagrammatically shown therein including a coil it of uncoated strip material mounted on 3,177,847 Patented -Apr. 13, i965 "ice a suitable uncoiling mechanism not shown. Strip material withdrawn from the coil Ill passes around guide roller 11 and upwardly along a substantially vertical pass and then around guide roller 12. The strip material upon its upward travel, as viewed in the drawing, along the sub stantially vertical pass, which is identified by reference numeral 13, moves past coating applicator 14 constructed in accordance with the present invention. As described in detail below, the coating applicator 14 functions to apply a coating of organic substance to one side of the strip material and the coated strip material after passing around roller 12 enters a curing furnace 15 which may be provided with a plurality of upper rollers 16 and a plurality. of lower rollers 17 to cause the strip material to traverse a plurality of passes 18 upon moving through the furnace. The furnace may be fired by any suitable means to maintain the required temperature for curing the organic coating and strip material having cured organic coating thereon leaves the furnace and is coiled in a coil 19 formed on a suitable coiling mechanism, not shown, which functions to move the strip material through the line at the required rate of speed. Rollers which guide the strip material when coating is uncured, such as rollers 12 and at least certain of the rollers 15 and 17 within the furnace, are designed to support the strip material in such a manner as not to mar the coating. For example, the strip material may be supported by contact with the edges only of the strip material; rollers of the type shown in Patent 2,979,829 are suitable for this purpose.

The coating applicator 14 is shown in more detail in FIGURE 2 and includes a cylindrical roller 20 and a distributor 21 for transferring liquid coating substance to the roll 241 The roll 20 is of cylindrical form and is provided with a polished external surface and is preferably constructed of metal. As shown in FIGURE 3, shafts 22 and 23 are provided at opposite ends of the roll Zil and the shafts 22 and 23 are supported in

bearing blocks

24 and 25, respectively, to rotatably mount the roll 29 with its longitudinal axis lying in a horizontal plane. The

bearing blocks

24 and 25 are slidably mounted between pairs of vertically spaced

lateral guide members

26 and 27 supported by

standards

28 and 29. The feature of supporting the shafts of the roll 20 by slidably mounted bearing blocks makes it possible to adjust the lateral position of the axis of rotation of the roll. The bearing blocks may be laterally adjusted by any suitable means such as by an arrangement as shown in FIGURE 4 including an elongated member 30 threadedly supported in standard 28 and attached to a bearing block to permit rotation of the member 30 to thereby impart lateral movement to the bearing block. The roll 20 is positively rotated by means of a variable speed drive 31 coupled to the shaft 23 as indicated by broken line 32.

' The distributor 21 for liquid coating substance includes an elongated hollow member 35 having closed ends to define an elongate'charnber 36 for receiving liquid coating substance, the member may be of any desirable crosssectional' shape. Liquid coating substance is supplied to the chamber 35 by a variable capacity pump 37 connected to the chamber 36 by a conduit 38 which may communicate with the chamber 36 along its length or at one or both of its ends; the pump .37 being connected to a source of coating substance by conduit 39.' The distributor 21 also includes an elongated feeder plate 40 joined to or merging from the underside of the member and extending substantially throughout its length. The wall of the elongated member 35 includes means forming an elongated slot 41 which extends longitudinally of the member 35 substantially throughout its length and parallel to its longitudinal axis. The slot 41 is located in the region of the merged or joined edge of the feeder plate with the member 35 so that the slot 41 discharges or opens onto the upper surface 42 of the feed plate. The feeder plate 40 extends from the right hand side of the member 35, as viewed in FIGURE 2, and downwardly and terminates in a knife edge 43. An elongated metering blade 44 may be adjustably positioned by any suitable means, not shown, on the elongated hollow member 35 adjacent the elongated slot 41 to regulate the quantity of coating material flowing through the slot onto the surface 42 of the feeder plate and the metering blade may be provided with calibrated serrations on its metering edge 45 if desired.

The elongated hollow member 35 is provided with end supports and 51 mounted in

blocks

52 and 53, respectively, which are slidably mounted between lateral members 27 j and adjacent vertically spaced upper lateral members 54. The

slidable blocks

52 and 53 each may be adjusted laterally by any suitable means such as by an elongated threaded member 55 shown in FIGURE 4.

In accordance with the principles of the present invention the roll 20 is positioned relative to the strip material to establish line contact with one surface of the strip material; preferably the line contact is disposed in a hori zontal plane and for this purpose the strip material moves upwardly through the pass 13 with its edges lying in substantially vertical planes and the roll 20 rotates about a substantially horizontal axis. The

bearing blocks

24 and 25 are laterally adjustable to establish the line contact relationship with one surface of the strip material. As shown in.FIGURE 2, the distributor 21 is positioned relative to the roll 20 so that the feeder plate 40 is inclined downwardly and in a direction toward the roll 20 with its terminating edge 43 parallel to the longitudinal axis of the roll 20 and closely spaced above the surface of the roll 20 in a vertical plane positioned between the strip material and the axis of rotation of the roll 20. The required positioning of the terminating edge 43 of the feeder plate relative to the roll 20 may be accurately established by adjusting the laterally

movable blocks

52 and 53. The angle of inclination of the feeder plate is such as to cause the liquid coating substance to flow under the influence of gravity from the slot 41 uniformly over the surface 42 and uniformly from the terminating edge 43 onto the roll 20.

As mentioned above, the strip material, upon moving through the pass 13, moves vertically upwardly as indicated by arrow A. In accordance with the principles of the present invention the polished surface on the roll 20 moves in a direction opposite to the direction of movement of the strip material and thus the roll 20 is rotated by the variable speed drive 31 in a clockwise direction as indicated by arrow B; the movement of the polished surface of the roll 20 being small as compared to the movement of the strip material.

In operation, the variable capacity pump 37 is adjusted to supply a sufficient rate of flow of liquid coating substance to the chamber 36 by way of the conduit 38 to maintain liquid coating substance within the chamber 36 under constant pressure so that liquid coating substance uniformly flows past the metering end 45 throughout the length of the slot 41 and uniformly over the inclined surface 42 and from the edge 43 onto the outer surface of the roll 20. Clockwise rotation of the roll 20 moves the liquid coating substance downwardly and a pool of liquid coating substance is formed between opposing surfaces of the strip material and the outer surface of the roll 20 immediately above the line contact between the roll and the strip material. The pool of coating substance extends throughout the width of the strip material and movement of the strip material past the pool 60 results in coating substance being applied uniformly to the strip material throughout its width.

The thickness of the coating applied to the strip material is a function of a number of variables including the speed of the strip material, the speed of rotation of the roll 20, and the rate of flow of liquid coating substance downwardly on the inclined surface 42 which in turn depends upon the size of the slot 41 and the output of the variable capacity pump 37. All of the foregoing factors relate to the size of the pool 60 and the size of the pool 60 relates directly to the thickness of the coating applied to the strip material inasmuch as the coating is applied to the strip material as a consequence of the strip material moving past the pool 60 of liquid coating composition. The feature of rotating the roll 20 in a direction opposite to the direction of movement of the strip material also makes it possible to control with great accuracy the thickness of the applied coating. The roll 20 performs a wiping function and moves liquid coating substance from the pool 60 past the line contact with the strip material. The quantity of liquid coating substance removed from the pool 60 increases as the speed of rotation of the roll 20 increases and thus the thickness of the applied coating may be regulated by varying the speed of rotation of the roll 20. Liquid coating substance moved by the roll 20 past the line contact is moved away from the strip material by the roll 20 and a doctor blade 61 is provided for removing such substance to provide a clean surface for receiving liquid coating composition discharged from the edge 43.

The feature of the present invention of liquid application of coating substance to the strip material unexpectedly obtains extremely smooth coatings even when the surface being coated is rough. It is believed that when the strip material moves. into contact with the pool 60 the liquid coating substance is forced into contact with the surface of the strip material due at least in part by the action of the counter-rotating roll 20 and all irregularities in the surface of the strip material are filled with liquid coating substance. Thereafter, when the strip material moves out of contact with the pool 60 liquid coating substance tends to move with the strip material but the liquid coating substance will shear with one part remaining on the strip material as the coating and another part returning to the pool. The plane in which this shearing action takes place will depend upon a number of factors including characteristics of the coating substance and the period of contact of the strip material with the pool 60 but in any event the shearing action takes place in a plane displaced from the surface of the strip material and is planar and uninfluenced by surface irregularities. While the foregoing is a theoretical explanation it is known that use of the applicator provided by the present invention makes it possible to obtain extremely smooth coatings uninfluenced by underlying surface irregularities as distinguished from coatings produced by prior apparatus in which films of coating of substantially the same thickness are applied uniformly to the surface of the strip material.

In the arrangement shown in FIGURE 2 of the drawings the roll 20 is in line contact with the strip material which moves from a region below the roll 20 upwardly along a path perpendicular to a horizontal plane passing through the'longitudinal axis of the roll 20 to a region above the roll 20. While this is the preferred relationship it is to be expressly understood that the path of the strip material need not be perpendicular to a plane passing through the horizontal axis of the roll but may be inclined with respect to such a horizontal plane either to the right or the left from the pass 13 shown in FIGURE 2. With the arrangement shown in FIGURE 2 inclination of the path of the strip material in a direction toward the distributor 21 is of course limited by the physical location of the distributor with respect to the roller however inclination of the path of the strip material in the opposite direction is not so limited. While in most instances it may be preferred to practice the invention with the strip material moving upwardly along a vertically disposed pass as shown in FIGURE 2, it may be desirable in certain cases to incline the plane of the path of the strip material. One reason for practicing the present invention with the plane of the strip material inclined would occur in instances where the coating substance has high fluidity or low rate of adherence or both. In any event, in order to practice the present invention it is necessary to establish line contact between the outside surface of the roll 20 and the surface of the strip material being coated with the angular relationship of the path of the strip material and a horizontal plane passing through the longitudinal axis of the roll being such so that a pool of coating substance of proper size to produce the desired coating is maintained between opposite surfaces of the strip material and the roll above the line contact. Although the cavity defined by opposite surfaces of the roll 20 and the strip material above the line contact is open ended the pool 60 is uniform throughout the usable width of the strip material since the cross-sectional area of the pool is extremely small relative to its length and since the pool is fed uniformly with liquid coating substance throughout its length.

The following are examples of actual operation of a continuous strip coating line embodying the principles of the present invention:

Example 1 Strip Material.-Steel strip with hot dipped galvanized spangled coating Gage: 0.0217 inch Width of strip: 43% inches Width of coated product: 42 inches Coating MateriaZ.Vinyl paint Viscosity: 34 seconds Zahn No. 1 cup Temperature: 130 F. Speed of strip material: 35 feet per minute Speed of rotation roll: 1 revolution per minute Flow of coating substance: .24 gal/min. Film thickness: 0009-001 Example 11 Strip MateriaL-Sheet strip coated with hot dipped galvanized coating Gage: 0.0217 inch Width of strip: 30% inches Width of coated product: 29 inches Coating MaieriaL-Vinyl paint Viscosity: 32 seconds Zahn No. 1 cup Temperature: 130" F. Speed of strip material: 47 feet per minute Speed of rotation of roll: 3 revolutions per minute Flow of coating substance: .20 gal./ min. Film thickness: .0007

The coated strip material produced from the foregoing examples was extremely smooth with very good adhesion and flexibility and excellent results were obtained from Zuhr, cone and mandrel tests.

It is to be expressly understood that the principles of the present invention may be employed to coat both sides of the strip material upon a single pass through a processing line. This may be accomplished by providing apparatus similar to the arrangement shown in FIGURE 2 for operation upon the other side of the strip material. Although, as discussed above, the present invention makes it possible to produce extremely smooth coating of precisional thickness it is to be understood that a leveler '6 roller, such as roller 62, may be used in connection with the principles of the present invention such as when extremely thick coatings are desired.

Although only one embodiment of the invention has been disclosed and described herein, it is to be expressly understood that various changes and substitutions may be made therein without departing from the spirit of the invention as well understood by those skilled in the art. Reference therefore will be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. In a coating apparatus, a smooth surface elongated cylindrical roll, means rotatably mounting the roll with its longitudinal axis disposed in a horizontal plane, means moving strip material along a path from a region located below the roll upwardly past the roll with one surface of the strip material in line contact with the roll to a region located above the roll, the path lying in a plane disposed in angular relationship with a horizontal plane passing through the longitudinal axis of the roll, means applying liquid coating substance to the roll along a length of the roll at least corresponding to the width of the strip material, means rotating the roll in a direction opposite to the direction of movement of the strip material to move liquid coating substance applied to the roll in a direction toward the one surface of the strip material, and means controlling the speed of rotation of the roll and the quantity of coating substance applied to the roll in accordance with the speed of the strip material to maintain a pool of liquid coating substance extending along the width of the strip material in the space defined by the portion of the one surface of the strip material above the line contact and the opposing surface portion of the roll.

2. In a coating apparatus, a smooth surface elongated cylindrical roll, means rotatably mounting the roll with its longitudinal axis disposed in a horizontal plane, means moving strip material along a path from a region located below the roll upwardly past the roll with one surface of the strip material in line contact with the roll to a region located above the roll, the path lying in a plane disposed in angular relationship with a horizontal plane passing through the longitudinal axis of the roll, an elongated hollow member defining a chamber and an elongated slot communicating with the chamber, an elongated downwardly inclined feeder plate extending from the slot to the roll, means for feeding liquid coating substance to the chamber, means rotating the roll in a direction opposite to the direction of movement of the strip material to move liquid coating substance applied to the roll in a direction toward the one surface of the strip material and form a pool of liquid coating substance extending along the width of the strip material and confined by the portion of the one surface of the strip material above the line contact and the opposing surface portion of the roll, and means controlling the speed of rotation of the roll and the quantity of coating substance applied to the roll in accordance with the speed of the strip material to apply coating of predetermined thickness to the one surface of the strip material.

3. In a coating apparatus, a smooth surface elongated cylindrical roll, means rotatably mounting the roll with its longitudinal axis disposed in a horizontal plane, means moving strip material along a path from a region located below the roll upwardly past the roll with one surface of the strip material in line contact with the roll to a region located above the roll, the path lying in a plane disposed in angular relationship with a horizontal plane passing through the longitudinal axis of the roll, an elongated hollow member defining a chamber and an elongated slot communicating with the chamber, and elongated downwardly inclined feeder plate extending from the slot to the roll, means for feeding liquid coating substance to the chamber, the elongated feeder plate terminating in a plane intermediate the path of the strip material and a vertical plane passing through the axis of rotation of the roll, means rotating the roll in a direction opposite to the direction of movement of the strip material to move liquid coating substance applied to the roll in a direction toward the one surface of the strip material and form a pool of liquid coating substance extending along the width of the strip material and confined by the portion of the one surface of the strip material above the line contact and the opposing surface portion of the roll, and means controlling the speed of rotation of the roll and the quantity of coating substance applied to the roll in accordance with the speed of the strip material to apply coating of predetermined thickness to the one surface of the strip material.

ReferencesCited by the Examiner UNITED STATES PATENTS Hodgman 118-407 X Faulkner 1 1 18-407 Obenshain et a1 118-259 X Cook et a1 118419 X Hornbostel 1 18 Uhleen 118-118 X Stickel 1 18-407 Colwill et a1 118-259 X RICHARD D. NEVIUS, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,177,847 April 13, 1965 Joseph E. Schnierlein It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 23, for "rollers" read roller column 3, line 10, for "feed" read feeder column 5, line 44, for "Speed of rotation ro1l:" read Speed of rotation of roll: column 6, line 70, for "and" read an Signed and sealed this 28th day of September 1965.

(SEAL) Auest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents