US3273535A

US3273535A - Trailing-blade-coater including adjustable drag-blade

Info

Publication number: US3273535A
Application number: US408716A
Authority: US
Inventors: Krikorian Garo
Original assignee: Rice Barton Corp
Current assignee: Rice Barton Corp
Priority date: 1964-10-06
Filing date: 1964-10-06
Publication date: 1966-09-20
Anticipated expiration: 1983-09-20

Description

P 1966 G. KRIKORIAN 3,273,535

TRAILING-BLADE-COATER INCLUDING ADJUSTABLE DRAG-BLADE Filed Oct. 6, 1964 5 Sheets-Sheet l Sept. 20, 1966 G. KRIKORIAN TRAILING-BLADE-COATER INCLUDING ADJUSTABLE DRAG-BLADE 5 Sheets-Sheet 2.

Filed Oct. 6, 1964 p 0, 1966 KRIKCRIAN 3,273,535

TRAILING-BLADE-COATEH INCLUDING ADJUSTABLE DRAG-BLADE Filed Oct. 6, 1964 5 Sheets-Sheet 5 United States Patent 3,273,535 TRAILING-BLADE-COATER INCLUDING ADJUSTABLE DRAG-BLADE Garo Krikorian, Paxton, Mass., assignor to Rice Barton Corporation, Worcester, Mass., a corporation of Massachusetts Filed Oct. 6, 1964, Ser. No. 408,716 Claims. (Cl. 118-410) This application is a continuation-in-part of my prior application, United States Serial No. 206,378, filed June 29, 1962, for Liquid Applying Coaters and now abandoned.

The present invention relates to improvements in liquid applying coaters and more particularly to a drag blade for controlling the circulation of the liquid coating within the enclosure for said coating which is induced by the rapid passage of the web through the liquid and thereby to establish a better control of thickness and uniformity of said coating.

The invention is disclosed in a preferred form as embodied in a trailing blade type coater in which the web is passed downwardly around a backing roll past a liquid coating enclosure and doctor blade assembly which includes an enclosure for liquid coating material having an open face against said web and an enclosed rear face, and a doctor blade having a web engaging edge enclosing the bottom of said enclosure. In the operation of a coater of this general description, particularly when the web is driven at high speeds, a condition of turbulence tends to be set up within the enclosure which tends to produce an uneven distribution of the coating with consequent streaking and spotting of the coated web.

It is a principal object of the invention to provide a novel and improved device for controlling turbulence and any consequent tendency toward uneven distribution, streaking or spotting of the coating produced by the passage of the web through the reservoir under conditions of high-speed operation.

It is a further object of the invention to provide a reliable, readily adjustable means to accurately control the weight of the coating deposited on the traveling web.

With these and other objects in view as may hereinafter appear, a feature of the invention consists in the provision of a drag blade which is of a length to extend across the web and supported to extend from outside beneath the surface of the liquid coating, said drag blade being located adjacent the web at the point of entry of said web and drag blade into the liquid coating shielding the entering portion of the web from contact with the liquid coating and with the submerged inner edge of the drag blade spaced from the doctor blade so that that portion only of the traveling web beneath the surface of the liquid extending from said inner submerged edge of the drag blade to the leaving edge defined by the yieldable trailing edge of the doctor blade is in contact with the liquid coating.

The drag blade may be formed of a heavy gage steel which is pre-shaped to conform accurately to the curvature of the backing roll supported web, or may be formed of a flexible or pliable material to be suspended from above the reservoir adjacent the traveling web, so that the blade tends to be swayed and bent by the forces set up within the reservoir by the rapidly moving web to a position adjacent to and with a contour which is conformed generally to the curvature of the traveling web.

When the drag blade is thus located with the lower portion thereof projecting within the reservoir in a position closely adjacent the traveling web the liquid coating is engaged only with a portion of the traveling web below the liquid surface producing a smooth, even flow of the liquid Without turbulence or other disturbance. The eddy 3,273,535 Patented Sept. 20, 1966 "ice currents thus set up tend to bend and to mold the blade against the Web, this tendency, however, being offset by an air suction set up between the traveling web and the blade which acts to support the blade in a narrowly spaced closely adjacent position with relation to the web.

Another feature of the invention consists in the provision of means for adjusting the position of the drag blade in an upward and downward direction to vary the spacing of the lower immersed edge of the drag blade from the doctor blade closing the lower or leaving side of the open face of the liquid coating enclosure.

The several features of the invention consist also in the devices, combinations and arrangement of parts hereinafter described and claimed which together with the advantages to be obtained thereby will be readily understood by one skilled in the art from the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a detail sectional view in side elevation of a trailing blade type coater illustrating particularly the backing roll, the trailing doctor blade and coating pond assembly in combination with a drag blade mechanism, only so much of the machine having been shown as is believed necessary to show connection of the present invention therewith;

FIG. 2 is a plan view of substantially the parts shown in FIG. 1;

FIG. 3 is a view similar to FIG. 1 but with the drag blade in its raised position to illustrate the manner in which the increased loading and springing of the doctor blade will increase the thickness of the coating;

FIG. 4 illustrates a modified form of the invention in which the doctor blade and coating pond assembly are located directly beneath the backing roll and web;

FIG. 5 is a diagrammatic view illustrating an alternative form of the invention in which a second roller is provided in place of the doctor blade and coating pond assembly for applying a coating to the web;

FIG. 6 is a somewhat diagrammatic sectional view in side elevation similar to previous figures in which an extremely thin and flexible drag blade is employed in a pressurized coating pond assembly;

FIG. 7 is a detail plan section takes on a line 77 of FIG. 6;

FIG. 8 is a detail fragmentary view similar to FIG. 6, but on a larger scale showing the drag blade in a more open or withdrawn position of adjustment; and

FIG. 9 is a somewhat diagrammatic view similar to FIG. 7 in which a flexible drag blade is suspended within an open liquid coating container applied to a side of the backing roll and web traveling thereon.

Referring to FIG. 1 of the drawings, elements of a trailing blade type coater are shown including a backing roll 20 around which a traveling web 22 is drawn in a downward direction, and a coater head 24 which houses a liquid coating enclosure 26 and a doctor blade 28 mounted upon and closing the lower end of the enclosure 26. The coater head 24 is adjustably secured in position on supporting arms 30 which are attached to the two ends of the coater head. The two ends of the enclosure 26 are closed by means of dikes which may be of the general type indicated at 32 in FIG. 2. In the present construction there is also provided a drag blade 34 which extends across the width of the web between the dikes 32 and is curved as shown in cross section to conform substantially with the curvature of the web passing around the backing roll 20. The drag blade 34 is secured at its upper edge to a tubular member 36 which extends across the width of the backing roll 20. By way of contrast with the disclosure of FIGS. 6 and 7, the blade 34 is assumedto be of sufficient thickness to be self-supporting so that the desired curvature is maintained independently of the hydraulic forces set up in the bath by the rapidly moving web.

The tubular member 36 is supported at each end by two identical supporting structures one of which is shown in FIGS. 1 and 2. Each of the two supporting structures referred to comprises an open ring bearing 38 for the tubular member 36, said ring bearing 38 being formed on the projecting end of a plunger 40 which is slidably mounted in a block 42 rotatably supported on a cylindrical bar 46 which is secured to and forms an integral part of the color pond 24 and doctor blade 28 assembly. As best shown in FIGS. 1 and 2 the rod 46 is rigidly clamped adjacent each end in a split clamp 48 forming part of the color pond 24 assembly.

The supporting structures for the tubular member 36 and drag blade 34 are constructed and arranged for angular adjustment about the rod 46 to effect an up and down adjustment of the drag blade to control the width of the traveling web area exposed to the coating material in the color pond. A rotational adjustment of said supporting structure is employed to effect a corresponding forward and back adjustment of the plungers 40 and drag blade 34, and also to maintain the contoured inner surface of the drag blade in narrowly spaced relation closely adjacent the traveling web.

The plunger 40 is provided toward its rear end with a vertical slot 50 which receives a relatively fixed vertically disposed cam plate 52, the lower end of which is formed with a lateral extension 54 bolted to the rear face of the splint clamp 48. The rear edge of the cam plate 52 is formed with a cam surface 56 which is adapted for engagement with a follower roll 58 which extends across the rear end of the slot '50 in the plunger 40. The cam plate 52 extending through the slot 50 acts to support the assembly including plunger 40 and block 42 against axial movement on the rod 46. The cam surface 56 engaging roll 58 determines the forward and back position of the plunger, which is biased in a forward direction by means of a spring 60 coiled about the plunger between a collar 62 on the plunger and a recessed shoulder 64 in the block 42. The contour of the cam 56 is such that rotata-tional movement of the block 42 and supported plunger 40 about the axis of shaft 46 Will effect a corresponding forward or back movement of the shaft 40 which causes the tubular member 46 and drag blade 34 to be maintained for all angular adjustments of the supporting assembly closely adjacent the surface of the web 22 and backing roll 20. The up and down adjustment of the drag blade assembly above described is accompanied by a corresponding angular adjustment of the shaft 36 and drag blade 34 so that the lower edge of the drag blade is also maintained in its proper position closely adjacent the traveling web. To this end there is secured to the block 42 a plate 68 which is secured by screws 70 to one side of the block 42 and which is provided with a forwardly and upwardly extending arm 72 providing a cam surface which is engaged by a roller 74 mounted on a short rearwardly extending post 76 secured to the tubular member 36.

Each block 42 together with the associated plunger 40 and cam plate 68 is rigidly held in adjusted position on the cylindrical bar 46 by means of a set screw 78 screw threaded through a lug 80 in the cam plate 68 for engagement with one of a series of indents 82 in the surface of the cylindrical bar 4 6.

Adjustment of the vertical position of the drag blade 34 is effected by varying the angular position of the blocks 42 on the cylindrical bar 46 in the following manner:

Assuming that the blocks 42 are adjusted in a clockwise direction from the full-line position shown in FIG. 1, the movement of the rollers 58 on their cams 56 will permit a forward movementof the two plun-gers 40 under the influence of springs 60 to maintain the tubular member 36 upper edge of the drag blade 34 in the desired position of adjustment with respect to the traveling web. At the same time the movement of the post 76 and roll 74 with relation to the cam extension 72 will control the angular position of the tubular member 36 and drag blade 34 to maintain the lower edge of the drag blade in the desired spaced relation to the traveling web and blade. The roller 74 is held against its cam 72 by any convenient means as, for example, a spring 84 tensioned between a pin 86 on the upper side of the tubular member 36 and a pin 88 on the split clamp 48. If no such biasing spring is provided, the forces generated by the rapidly moving web which include air suction between the web and the inner surface of the drag blade, and the eddy currents induced in the liquid within the reservoir may be expected to maintain the drag blade in approximately the desired position.

The drag blade 34, located in close proximity to the rapidly moving web, has the affect of shielding the web from the coating material in the enclosure over an area which extends from the level at which the web passes below the surface level of the liquid coating to the level of the emergence of the web from behind the bottom edge of the drag blade 34. With this arrangement a pull is exerted upon the liquid coating 22 only during the short extent of travel of the web from the line of its emergence from beneath the drag blade 34 to the line of engagement with the doctor blade at the bottom tip of the en closure. The liquid is thus caused to circulate in a manner which completely avoids the turbulence, splattering, and uneven pulling action which results when the rapidly moving web is brought directly into contact with the surface of the liquid coating.

An upward or downward adjustment in the position of the drag blade 34 has the effect of correspondingly varying the drag length during which a. pull is exerted on the liquid coating by the traveling web. A plurality of adjusted positions of the drag blade are shown in FIG. 3, said different positions of the drag blade 34 being indicated by the characters x to x inclusive. It will be noted that with each upward adjustment of the drag blade there is a tendency for a greater amount of the liquid material drawn down to be forced under pressure against the top face of the doctor blade 28. As the weight of the liquid material being forced against the blade 28 increases, the blade is caused to bend outwardly thus increasing the thicknesses of the resulting coat.

An alternative embodiment of the invention is shown in FIG. 4 of the drawings in which the coater head designated at 90 is engaged against that portion of the web 22 which is directly beneath the backing roll 20. The liquid coating supplied to the enclosure through inlet 92 in this case is maintained under some pressure which insures an intimate contact of the coating with the traveling web between the tip edge of the drag blade 94 and the edge of the doctor blade 96. In this form of the apparatus the drag blade 94 extends from without the within the area occupied by the liquid coating enclosure, and is supported on arms 97 pivoted upon and extending radially from the axis of the roll 20. A seal 98 interposed between the underside of the drag blade and the entering edge of the enclosure prevents leakage of the coating at this point. As shown in FIG. 4 the surface of the liquid and the entering edge of the enclosure 90 coincide. traveling web exerts a drag upon the liquid coating which extends from the terminal edge of the drag blade 94 to the point of engagement with doctor blade 96 The liquid in the enclosure is thus put in motion traveling in a circular path which is substantially free from turbulence so that the liquid is forced evenly and under constant pressure against the face of the doctor blade. In this form of the device, the surface of the liquid and the entering edge of the enclosure coincide. The adjustment of the forward and back position of the drag blade 94 about the axis of rotation of the backing roll 20 is controlled by angular adjusting of the supporting arms 97 The,

about the rotational axis of the backing roll 20, and has the effect of correspondingly varying the weight of the liquid coating forced against the inner face of the doctor blade and consequent thickness of the coating applied to the web.

Still another application of the drag blade in accordance with the present invention is shown in FIG. 5, in which there is shown a backing roll 1% which provides support for the traveling web 22. For applying a coating to the web 22 there is provided a coating roll 1114 which is mounted in parallel relation to the backing roll 100 in a position to provide a liquid coating applying hip to the web 22. A pool of liquid coating 106 is formed above and beneath the two rolls. FIG. is intended only as a diagrammatic disclosure of the modification. It will be understood that dikes of ordinary description such as that shown at 32 in FIG. 2, but contoured to fit between the rolls 1% and 164 as suggested at 107 in FIG. 5 may be employed to close in the ends of the pool. In this form of the apparatus two drag blades -8, .111 are provided, the drag blade 1% being supported on arms 112 pivoted on axis 114 of roll 1% to be located in close proximity to the traveling web 22 and backing roll 1% in such a position that it extends from above the level of the liquid pool 1116 to beneath the surface thereof. The drag blade 1111 is mounted to extend across the width of the coating roll 164 in close proximity thereto and similarly extends downwardly into the liquid coating from a point substantially above the surface thereof. The drag blade 114i is mounted on arms 116 carried on the axis 118 for the coating roll 1134. In this form of the device the thickness of the coating applied to the traveling web will depend on the up and down adjustment of each of the two drag blades 1138, 110.

FIGS. 6, 7 and 8 illustrate a further embodiment of the invention in which the drag blade is a flexible element, here shown as a very thin gage steel blade, although the blade may consist of a non self-supporting limp or pliable material such as sheet rubber or the like. In FIGS. 68 the backing roll is designated at 130 and the traveling web at 132. A liquid coating container 133 is provided which consists of doctor blade holder 134- secured to a transverse frame member 136, and a doctor blade 138 supported in the holder for trailing engagement with the underside of the backing roll 13% and traveling web 132. The rear side of the liquid coating container is closed by a preferably resilient member 139 supported in a frame 14!) attached at its lower edge by a hinge 141 to the holder 134, and along its upper edge secured to a transverse frame member 142 which is mounted closely adjacent the backing roll 130 and traveling web 132. The ends of the liquid coating container are closed by dikes 144 shown in FIG. 7. Liquid coating is supplied to the liquid coating container 133 above described by means of a pipe 145 connected at one end to an inlet 146 for the con tainer and at its other end extending downwardly within a liquid coating storage tank 143. In the illustration shown the liquid coating is supplied to the container 133 under pressure, the tank 148 being pressurized for this purpose by compressed air supplied through an inlet pipe 150 from a supply source, not shown. Air pressure is controlled by a valve 152 in the air inlet line 150, and further by a safety valve 154 fitted into the topof the tank.

In this form of applicants invention a very flexible thin gage steel drag blade 156 is employed which is introduced through a narrow opening provided between the back side of the container 133 and the traveling web 132. The drag blade 156 is supported along its upper edge by a transverse holder 158 provided at intervals along its length with screw bolts 160 screw threaded to cooperating nuts 162 rotatably fitted in apertures provided in an offset upper edge portion 164 of the transverse support 136. To prevent loss of the liquid coating through the opening at the upper edge of the transverse frame member 142,

a rubber bead or similar flexible sealing element 166 is provided, fitted into an angle provided between the trans verse frame member 142 and the frame 140 for engagement against the outer face of the drag blade 156.

The direct engagement of the liquid coating with the exposed portion of the traveling web 132 between the lower edge of the drag blade 156 and the point of engagement of the web with the doctor blade 138 gives rise to viscous drag forces and eddy currents which cause the flexible drag blade 156 to be pressed toward the back roll and web so that the contour of the inner face thereof tends to be conformed substantially to the path of the traveling web. A depth adjustment of the drag blade into the container to vary the width of web exposed to the liquid coating between the lower edge of the drag blade and the doctor blade is effected by adjustment of the nuts 162. The withdrawal of the drag blade 156 to the position of FIG. 8, for example, by substantially increasing the area of the traveling belt directly in contact with the coating fluid, will increase the downward flow of fluid and correspondingly increase the deflection of the doctor blade 138. Further control of coat thickness is effected by variation in the air pressure at the valve 152 which thus increases or decreases, as the case may be, the fluid pressure within the liquid coating container 133, and correspondingly the mass of the liquid coating which is forced by the doctor blade 138. With these adjustments, required adjustments and corrections in the flow and thickness of coating deposited on the web can be made readily during continued operation of the coater.

FIG. 9 illustrates a further modification of the invention in which the highly flexible drag blade 156, secured along its upper edge to the transverse bar holder 158, is supported from without to extend within a body of liquid coating contained in an open container 174 located at one side of the backing roll and traveling web 132. The container 174 comprises the doctor blade holder 134 and doctor blade 138 secured to a transverse frame member 176, and end dikes which may be similar to those shown at 144- in FIG. 7. The drag blade 156 and holder 158 are suspended from a bent over edge 17 8 of the transverse frame member 176 by means of screw bolts 160, pivotally connected with the bar holder 15% of the drag blade 156, and screw threaded toward their upper ends through rotatable nuts 162 rotatably supported in apertures in the bent over edge 178.

The highly flexible drag blade 156, suspended as shown in FIG. 9 and also as shown in FIGS. 6-8, extends from outside beneath the surface of the liquid in the liquid coating container 133, is disposed in narrowly spaced parallel relation to and closely adjacent the traveling web across the width of the opening in the container, and is acted upon in such a manner by the traveling web and liquid currents set up in the container that the contour of the face of the drag blade is conformed substantially to the path of the back roll supported web. The rapid movement of the web 132 causes an air draft to be introduced between the web and the drag blade 156 producing an air film, which, although it may be only a few millionths of an inch in thickness, will cushion the drag blade slightly away from the web and will also prevent liquid from seeping under the bottom edge of the blade.

It will be understood that the flexible drag blade 156 may be substituted for the heavier gage drag blade 34 in the liquid reservoir and doctor blade assembly of FIG. 1, and that said flexible blade when so installed will operate in a manner similar to the drag blade 34 to control turbulence and the thickness and quality of the coating produced.

It will be understood further that the invention in its broader aspects is not limited to the specific embodiments shown and that modifications may be made within the spirit and scope of the appended claims in the precise composition, shape and surface texture of the drag blade 7 supported adjacent the traveling web at the point of entry into the body of liquid coating to shield said entering portion of the web, so that only a submerged portion of the traveling web extending from the lower edge of the drag blade to the leaving edge of the container defined by the yieldable trailing edge of the doctor blade is in contact with the liquid coating.

The invention having been described what is claimed is:

1. In a coater having a backing roll around which a traveling web to be coated is drawn, a liquid coating reservoir and doctor blade assembly which comprises a liquid coating enclosure having an open face disposed against said web and supporting backing roll; a trailing type doctor blade forming a base portion of said enclosure and having the trailing edge thereof yieldably supported with relation to said traveling web in position closing the leaving edge of said open face; a drag blade disposed in narrowly spaced relation to said traveling web across the width of the web and having the face thereof conformed generally to the web and backing roll over which the web passes; said drag blade extending from above the top face of said liquid coating material and terminating in an inner submerged edge spaced from said doctor blade thus forming a wall of said enclosure and generally preventing contact of said material with the traveling web portion contiguous to said drag blade so that substantially that portion only of the traveling Web extending from said inner submerged edge of the drag blade to the leaving edge defined by said doctor blade is in contact with said liquid coating; and adjustable supporting means on which said drag blade is shiftable relatively to said backing roll to vary the width of the space between the inner submerged edge of the drag blade and the doctor blade and thereby the thickness of coating material driven past the yieldable trailing edge of said doctor blade.

2. In a coater having a backing roll around wh ch a web to be coated is drawn, the combination of a liquid coating reservoir and doctor blade assembly according to claim 1 in which the drag blade is a rigidly formed self-supporting element having a face adjacent said web contoured substantially to the curvature of the traveling web,

3. In a coater having a backing roll around which a web to be coated is drawn, the combination of a liquid coating reservoir and doctor blade assembly according to claim 1 in which the drag blade is a flexible and pliable element which tends to be conformed to the curved traveling web by forces set in motion by the traveling web.

4. In a coater having a backing roll around which a web to be coated is drawn, the combination of a liquid coating reservoir and doctor blade assembly according to claim 3 in which the drag blade is a thin flexible metallic element which tends to be conformed to the curved traveling web by forces set in motion by the traveling web.

5. For use in a coater having a backing roll around which a traveling web to be coated is drawn, and a liquid coating reservoir and applicator assembly which comprises, in combination, a. liquid coating enclosure having an open face disposed against said web and supporting backing roll; and a liquid coating applicator disposed upon the leaving edge of said liquid coater; a drag blade disposed in narrowly spaced parallel relation to said traveling web of a length to extend across said web, and curved to substantially the radius of curvature of said web, said blade entering the surface of the liquid coating from the entering side of said enclosure and terminating beneath the surface of said liquid in a lower edge spaced from said applicator thus forming a wall of said enclosure and generally preventing contact of said material with the traveling web portion contiguous to said drag blade; and a support assembly for said drag blade comprising a plurality of supporting structures having a common rotational axis fixed with relation to said enclosure and parallel to the axis of said backing roll, each said structure comprising a plunger pivotally connected at its outer end with said drag blade, a sleeve support block rotatably adjustable on said axis providing a sleeve support for said plunger, a cam follower supported on said plunger in combination with a cam fixed with relation to said enclosure, said cam and follower being conformed for any angular adjustment of said sleeve support to effect a corresponding movement of the lunger axially as it is carried through said angular adjustment and tending to thereby impart to the drag blade a resultant compound movement; and cam and follower connections between said plunger and drag blade conformed for any said combined axial pivotal movement of said plunger to maintain constant said closely spaced parallel relationship of the blade to the peripheral surface of the backing roll, the drag blade thus having a total movement which is arcuate with respect to the traveling web contiguous therewith and the backing rolls.

6. In a coater having a backing roll around which a web to be coated is drawn, and a drag blade according to claim 1, the combination of having a liquid reservoir and doctor blade assembly pivotal supporting means coaxial with said backing roll axis on which said drag blade is shiftable arcuately about the backing roll axis to vary the width of said space and thereby the thickness of coating material driven past the trailing edge of said doctor blade.

'7. In a liquid material applying coater having a backing roll around which a web to be coated is drawn, and a liquid coating reservoir and applicator assembly which comprises a liquid coating enclosure having as one side of said enclosure the downwardly drawn web and supporting backing roll according to claim 1 the combination, in which the opposite side of said enclosure comprises an opposed liquid applying roll providing a liquid coating applying nip against a downwardly moving portion of the backing roll supported web, and a second drag blade similarly disposed in narrowly spaced relation to and closely adjacent said liquid applying roll extending from above the top face of and terminating beneath the surface of said liquid coating.

8. In a coater having a backing roll around which a web to be coated is drawn according to claim 1, the combination of dikes closing the two ends of said open face, and a resilient sealing element closing the web receiving edge of said open face, the drag blade is a flexible drag blade disposed across the width of said web extending between said resilient sealing element and web from outside the body of said liquid and terminating beneath the surface of the liquid with the submerged portion of said drag blade substantially conformed to the curvature of the traveling web and backing roll and with the submerged edge of said drag blade spaced from the doctor blade so that that portion only of the web traveling across said open face is in contact with said liquid coating, and a support to which the drag blade is attached externally of said enclosure.

9. In a coater having a backing roll around which a web to be coated is drawn, the combination of a liquid coating reservoir and doctor blade assembly according to claim 8 in which means are provided for supplying liquid coating under pressure to said enclosure.

10. In a coater having a backing roll around which a web to be coated is drawn, the combination of a liquid coating reservoir and doctor blade assembly according to claim 9, in which a portion of said enclosure is formed of resilient material in order to minimize pressure vari ations within said enclosure.

(References on following page) UNITED 9 References Citefi by the Examiner 2,75 8,336 STATES PATENTS 2,855,895 3,018,757 Bergman 117*11 3 0 4 924 Francis 5 3 1 Francis 118-413 X Ward 117-115 X Franssen 118415 X Burns et a1. 118407 Loppnow 118-262 Stack 101-364 X Eolkin et a1 118-7 X MORRIS KAPLAN, Primary Examiner.

Claims

1. IN A COATER HAVING A BACKING ROLL AROUND WHICH A TRAVELING WEB TO BE COATED IS DRAWN, A LIQUID COATING RESERVOIR AND DOCTOR BLADE ASSEMBLY WHICH COMPRISES A LIQUID COATING ENCLOSURE HAVING AN OPEN FACE DISPOSED AGAINST SAID WEB AND SUPPORTING BACKING ROLL; TRAILING TYPE DOCTOR BLADE FORMING A BASE PORTION OF SAID ENCLOSURE AND HAVING THE TRAILING EDGE THEREOF YIELDABLE SUPPORTED WITH RELATION TO SAID TRAVELING WEB IN POSITION CLOSING THE LEAVING EDGE OF SAID OPEN FACE; A DRAG BLADE DISPOSED IN NARROWLY SPACED RELATION TO SAID TRAVELING WEB ACROSS THE WIDTH OF THE WEB AND HAVING THE FACE THEREOF CONFORMED GENERALLY TO THE WEB AND BACKING ROLL OVER WHICH THE WEB PASSES; SAID DRAG BLADE EXTENDING FROM ABOVE THE TOP FACE OF SAID LIQUID COATING MATERIAL AND TERMINATING IN AN INNER SUBMERGED EDGE SPACED FROM SAID DOCTOR BLADE THUS FORMING A WALL OF SAID ENCLOSURE AND GENERALLY PREVENTING CONTACT OF SAID MATERIAL WITH THE TRAVELING WEB PORTION CONTIGUOUS TO SAID DRAG BLADE SO THAT SUBSTANTIALLY THAT PORTION ONLY OF THE TRAVELING WEB EXTENDING FROM SAID INNER SUBMERGED EDGE OF THE DRAG BLADE TO THE LEAVING EDGE DEFINED BY SAID DOCTOR BLADE IS IN CONTACT WITH SAID LIQUID COATING; AND AJUSTABLE SUPPORTING MEANS ON WHICH SAID DRAG BLADE IS SHIFTABLE RELATIVELY TO SAID BACKING ROLL TO VARY THE WIDTH OF THE SPACE BETWEEN THE INNER SUBMERGED EDGE OF THE DRAG BLADE AND THE DOCTOR BLADE AND THEREBY THE THICKNESS OF COATING MATERIAL DRIVEN PAST THE YIELDABLE TRAILING EDGE OF SAID DOCTOR BLADE.