US3104182A - Apparatus for controlling edge beads - Google Patents

Description

c. H. SCHNEIDER ETAL 3,104,182

APPARATUS FOR CONTROLLING EDGE BEADS Sept. 17, 1963 5 Sheets-Sheet 1 Filed April 28, 1961 M Y W m wd L o a mmr m n 1 1w 5m M m kw Fm} f \N N N \N m %w MN J m\\ 1 MN. MW

Sept. 17, 1963 c. H. SCHNEIDER ETAL 3,104,182

APPARATUS FOR CONTROLLING EDGE BEADS Filed April 28, 1961 5 Sheets-Sheet 2 INVENTOR.

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APPARATUS FOR CONTROLLING EDGE BEADS 5 Sheets-Sheet 3 Filed April 28, 1961 w mw INVENTORS jl ATTORNEY 1 Clzaz'lesliSclmeidmLes-lieRArIed ge, Herberflllizmflton; William G. Cassill BY W III II... I

Sept. 17, 1963 c. H. SCHNEIDER ETAL 3,104,182

APPARATUS FOR CONTROLLING EDGE BEADS 5 Sheets-Sheet 4 Filed April 28, 1961 ATTORNEY Sept. 17, 1963 c. H. SCHNEIDER ETAL 3,104,182

APPARATUS FOR CONTROLLING EDGE BEADS Filed April 28, 1961 5 Shee'ts-Sheet 5 3%; Mia;

ATTORNEY United States Patent 3,104,182 APPARATUS FOR CONTRGLLING EDGE BEADS Charles H. Sclmeider, Leslie R. Arledge', and Herbert 1).

Hamilton, Chillicothe, and William G. Cassill, Hamden, Ohio, assignors to The Mead Corporation, Dayton, Ohio, a corporation of Uhio Filed Apr. 28, 1961, Ser. No. 106,361 9 Claims. (Cl. 118-204) The present invention relates to apparatus for removal 0f material from a portion of a cylindrical surface, and more particularly to means for doctoring paper coating material from a coating roll so as to minimize or eliminate thickened ridges or beads of coating material immediately adjacent the dootored area.

Heretofore, various means have been suggested for removal of paper coating material fromthe ends of coating rolls so as to limit the width of coating applied by the roll to a width equal to orpreferably slightly less than the width of the paper web to which the coating is subsequently applied. Conventional doctoring means of the prior art, while effective in removing coating material from the roll surface in the area of contact between the doctor and the roll, almost invariably leave a thickened ridge or head of coating material immediately adjacent the doc tored area. These so-called edge beads are transferred to the paper web, along with the main area ofthe coating.

The greater thickness of coating in the edge bead requires rnore setting or drying time than the coating on the main area of the web, and if the coated web is wound into a roll as soon as setting or drying is accomplished for the main area of the coating on the web, the edge beads are incompletely set or dried, and cause adjacent wraps of the web in the wound roll to stick together by reason of the adhesive component present in the coating material. On the other hand, if the setting or drying is continued to the point where the greater thickness of the edge head is completely set or dried, the coating in the'comparatively thick edge bead may become brittle and crack as the web is Wound onto a roll. Such cracking can weaken or crack the edges of the paper web, with resultant web breaks in subsequent operations, such as calendering, printing and the like. I

. In any event, the greater setting or drying time required for the relatively thick edge bead requires a slower operating speed on the coating machine, with its attendant lower productivity and higher operating cost.

The process for producing highly glossed mineral coated paper generally known in the trade as cast coat ing, is particularly susceptible to reduced speed and ciliciency attributable to edge beads. Such relatively thick ridges of coating will frequent-lyleaive deposits on the casting surface which tend to build up, by repeated revolutions of the casting drum or belt, to the pointwhere the machine must be stopped and the accumulations laboriously removed by hand. Furthermore, any'deposits of coating material on the casting surface beyond the edges of the paper Web must be continually removed; otherwise this coating tends to build up by repeated application and become tightly adherent to the casting surface, fouling the surface and rendering it unfit for use and causing serious difficulties when the web shifts laterally or a wider web is to be coated. Prior attempts to continuously remove such coating material have not been wholly successful. I

These and other deficiencies of the prior art are substantially overcome by the apparatus of this invention which limits the applied coatings to a width slightly less than the width of the paper web and avoids the formation of thickened ridges or edge beads of coating at the extremities of the coated area of the weh.

Accordingly, it is an object of this invention to provide 3,194,182 Patented Sept. 17, 1963 and/ or operations.

Another and important object of the invention is to provide an improved apparatus for continuously producing high gloss cast surfaced mineral coated paper which overcomes the difficulties inherent in the prior'art methods and which are characterized by relatively low cost and freedom from processing details.

Still another object of the invention is the provision of one or more doctoring means arranged in a novel manner with respect to an applicator roll in a papermak ing and/or coating machine.

Other and more specific objects, aswell'as the novel characteristics of the apparatus which contribute jointly to the functional improvement, will appear hereinafter.

In the attached drawings: s 7

FIGURE 1 is a diagrammatic view in side elevation showing apparatus constructed in accordance with and for practicing the present invention;

FIGURE 1a is a diagrammatic view in side elevation showing modified apparatus for pmacticing this invention;

FIGURE 2 is a schematic showing, partly broken away and partly in elevation, illustrating the action of certain doctor blades forming a part of this invention;

FIGURE 3 is a schematic perspective 'view of another and more simplified form of the apparatus shown in FIGURE 2; 1 1 7 FIGURE 4 is a diagrammatic elevational view, partly broken away, of one of the doctor blades of FIGURES, showing the partial helical shape .of the line of contact of the end of the blade with the roll or cylinder surface;

FIGURE 5 is a greatly enlarged view, partly in section and partly broken away, showing the edge bead encountered through the use of prior art doctoring devices; v

FIGURE 6 is a greatly enlanged view, partly in section and partly broken away, showing the tapered, wedge! shaped edge of a coating film resulting from the practice of this invention;

FIGURE 7 is a diagrammatic elevationofanotherembodiment of the present invention; f

FIGURE 8 is a side elevation view, partly "in section and partly broken away, of the embodiment of FIGURE 7; and, v 1 FIGURE 9 is a front elevation viewed? the doctoring device shown in FIGURE 8.

Referring more particularly to the drawings, vthere is schematically shown in FIGUREl the principleem: ployed in the present invention. Rolls :18 and 19 in con-. junction with backing roll 12 serve to apply a fluent coat ing 23 onto the surface ota paper web 11. Backing roll 12 supports web 1-1 and rotates inthe'direction of travel of the web'as indicated by the arrows; The fluent coating 23 is maintained in a pool in the ni p trough formed by metering roll '18 and applicatonroll 19. The coating system shown is a reverse roll system, with rolls 18 and 19 turning in the direction of the arrows. A conventional doctor "blade 13 serves to retain the pool of coating 23 in the nip trough of rolls'18 and 19, This coating apparatus is the subject of United States-patent application Serial No. 50,635, filed August l9; "1960 (assigned to the same assignee as thislinvention), and form-s no part of the present invention. 7

Referring to FIGURE 1a, 14 indicates a large diam ter roll or drum which alternatively may be'nsed for certain processes of producing cast surfaced mineral coated paper. In this arrangement, metering and applicator'rolls 1 8 and 19 apply a film of fluent-coatingto the surface of roll or drum 14. Such coating him is therafter trans ferred intact to a paper web at a point and by means not shown in the Ifigure. Whether the described apparatus illustrated by FIGURE 1 is used for applying coating films directly to a paper web, or to the surface of a casting roll or drum as shown by FIGURE 1a, the novel edge doctor means of this invention, indicated generally at 20, may be used to considerable advantage.

As illustrated by FIGURE 2 of the drawings, there is mounted adjacent each end portion of the applicator roll 19 a group or series of doctor blades each of which is adjustably mounted upon supporting shaft 21 which shaft 21 is rotatable by means of a control arm 22 whereby all of the doctor blades may be moved into or out of contact with applicator roll 19. In each group of doctor blades, the innermost blade 20:: first comes into contact with applicator roll 19 to remove therefrom a portion of the fluid coating composition, indicated at 23 in FIGURE 1, which has been applied thereto. The next adjacent blade 20b is so arranged as to receive the fluid thus removed from roll 19 and at the same time to remove an additional portion of such fluid from roll 19. The outermost doctor blade 20a is so arranged that it receives the fluid from intermediate blade 20b and at the same time removes the remainder of the fluid coating composition from the outermost or edge portion of roll 19. Of course, it will be appreciated that instead of three doctor blades in each group as illustrated in FIGURE 2, there may be additional blades in each group, or only one of such blades may be utilized, depending on the demands of the particular coating operation.

One of the essential principles here involved is the provision of one or more of such doctor blades set at an angle to a generatrix of the applicator roll, and, in the case of multiple blades, arranged in consecutive overlapping circumferentially disposed paths with relation to the rotating surface of an applicator roll. While one single doctor blade might be arranged in contact with a certain end portion of a roll, the greater the width of such end portion, the greater the chances of inaccuracies in the proper contactual relationship between the edge of the doctor blade and the surface of the roll with which it is in contact. In those instances where an appreciable width of applicator roll end portion is to be doctored, the doctoring is preferably accomplished by utilizing a plurality of such doctor blades, thus making possible a greater accuracy in proper contact between the blade and the roll. By arrangement of such plurality of doctor blades in the manner shown in FIG- URE 2, that is to say in overlapping contact with circumferential paths of travel of an applicator roll and further in such manner that, proceeding outwardly from the innermost blade, each adjacent blade is adapted to receive thereon the fluids removed from the roll by an immediately inwardly located blade while at the same time cleaning a portion of the roll in itself, the outermost of such blades being adapted to deliver the entire amount of liquid removed from the roll to a remote point fordisposal.

The unique doctoring action of the doctor blades is best shown in FIGURES 3 and 4 wherein a single blade form of the invention is illustrated and indicates the bending or flexing of doctor blade 20 as it is urged against the surface of roll 19. The curvature of the blade tip or end, remote from the clamping means, is a consequence of its conformity, over at least a portion of its width, to the curvature of the surface of roll 19. The force pushing the blade tip against the roll, imparted by supporting shaft 21 and control arm 22, FIG- URE 2, causes the central portion ofthe blade tip to assume a screw or helical shape. The width of the central portion of the blade in actual contact with the roll is greater, the greater the force urging it against the roll, and, if such force is great enough, the entire width of the blade would bend to a helical shape at its tip. However, such high force is to be avoided when practicing this invention, as it is an important feature that the extremities of blade tip 25, 26 do not engage the roll surface, although a central portion is so engaged as shown at 27. The portion of blade tip 26, which is not in direct contact with roll 19 extends at an acute angle to its projection on the surface of roll 19, and, as roll 19, carrying a film of coating, rotates past the blade in the direction of the arrow, FIGURE 4, the edge of the film of coating remaining on the roll is tapered or shaved as shown at 29. The portion of blade 27, in actual contact with roll 19 removes the coating material from a relatively narrow circumferential part of the end portions of roll 19. It is only necessary that a circumferential band of clean roll surface be provided, and such band be located so that the edges of the paper web fall roughly in its center portion, as shown at 30 in FIG- URE 7. The straight blade type doctors shown at 20 in FIGURE 3 may be used for this purpose, or doctors of the type shown in FIGURES 7 to 9 may be used to advantage to achieve this result.

Doctors of the type shown in FIGURES 7 to 9 are generally cylindrical in cross section, with one end cut at an angle to the long axis of the cylinder. Referring to FIGURE 8, the doctor is shown generally at 31. A metal tube 32, with its upper end cut at an angle to its long axis, is provided with a doctoring member 33 which is made of relatively stiff sheet material such as, for example, rubber, leather, plastic sheeting or the like. Doctoring member 33 is wrapped around tube 32 and secured to said tube as by clamp 34. Rod 35 extends through diametrically aligned holes drilled in tube 32, and is secured thereto as by welding as shown at 39. Rod 35 extends through a hole in block 36, and is adjustably secured therein by thumb screw 37. The upper portion of block 36 is provided with a hole at right angles to rod 35, through which extends supporting shaft 21. Block 36 is adjustably secured to shaft 21 by thumb screw 38. The arrangement of rod 35, block 36 and supporting shaft 21 permits adjustment of the doctor into any desired position with respect to roll 19.

The doctoring edge of doctoring member 33 extends slightly beyond the upper end of tube 32, and has a cutaway portion 40 and a doctoring portion 41. The outer lip of doctoring portion 41 is beveled slightly as shown at 42. While doctoring member 33 may be made from tubular material such as rubber or plastic hose, it may also suitably be cut from fiat sheet material and then wrapped around metal tube 32. In either case, the doctoring member is fixed in position, relative to tube 32 by clamp 34.

In operation, cylindrical doctor 31 is arranged to contact roll 19 along its doctoring portion 41, whereby it it removes coating film from a cylindrical band around the periphery of roll 19, as shown in FIGURE 7. The edges of the film of coating material on either side of the cleaned area or band are tapered, in the same manner as shown in FIGURE 6, and edge beads are not formed. The marginal edges of the paper web are free of coating, and, since no drying or setting occurs on ba'cking roll 12, the presence of fluid coating on the end portions thereof is without significance.

The coating fluid removed from the circumferential bands on roll 19 by doctor 31 flows by gravity down the inside of tube 32, and is conducted to a point remote from the coating apparatus, as shown at 43 in FIGURE 8. It will be recognized, of course, that the line of contact of the cylindrical doctor 31 with coating roll 19 is not a screw curve, as described for blade type doctors supra, but will take the form of a somewhat flattened circular arc. Again, the tapering of the edge of film of coating material left on roll 19 is accomplished by portions of doctoring member 33 on either side of doctoring portion 41 of said member, as indicated at 44 and 45 in FIGURE 9. Portions .4 and 45 of doctoring member 33, when in operating condition, make an acute angle with their projections on the surface of roll -19, and have a shaving or plowing action on the film of coating fluid which tapers the edge thereof, and moves the portion of coating fluid removed by such plowing action toward the central portion 41 of doctoring member 33. From this point, gravity flow through tube 32 conducts the coating fluid to a remote point as aforesaid.

While but two embodiments 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.

This application is a continuation-in-part of United States Serial Number 730,377, filed April 23, 1958, now abandoned.

What is claimed is:

1. In a coating machine having a cylindrical roll carrying a film offluid coating material on the surface thereof, a doctoring device for removing said coating material from an end portion of the surface of said roll comprising a doctoring member having a tip portion, the central part of which contacts said roll surface in a curved line, said member having portions forming acute angles with their projections on the surface of said roll whereby the edges of the film of coating material adjacent the doctored area of the roll surface are tapered toward a feather edge and free of thickened ridges of said coating material.

2. The doctoring device of claim 1 wherein the said doctoring member is a flat blade set at an angle to the generatrix of said roll and said line of contact of the central part of the tip portion of said blade with said roll surf-ace is a curved line having a helical shape.

3. The doctoring device of claim 1 wherein the said doctoring member is of curvilinear tubular form, the tip portion of which is cut away at an angle to the axis of said cylinder.

4. In :a coating machine, a doctoring device for removing coating material from an end portion of the surface of a cylindrical roll, comprising a flat flexible doctor blade set at an angle to the generatrix of the said roll, means for clam-ping said blade at said angle, and means to press said blade against said roll under sulficient pressure to cause said blade to deform at its tip into a partial helix, said blade tip not contacting said roll surface over its full width, whereby coating material is removed from said roll where said blade is in contact with said roll, and the edge of said coating material adjacent the area where said coating material has been removed is tapered toward a feather edge by the plowing action of the said blade at either edge of said blade.

5. In a coating machine having a cylindrical roll carrying a film of fluid coating material on the surface thereof, a doctor blade formed by cutting one end of a cylindrical docto-ring member at an angle to the long axis of the cylinder, means for clamping said blade adjacent the surface of said roll, means to press said doctoring member in contact with said roll under sufficient pressure to cause said doctoring member to deform at its tip into a flattened curve, said blade tip having a cut away portion so that it contacts said roll surface over only a portion of its projected width whereby said film of coating material is removed from said roll where said doctoring member is in contact with said roll and the edges of the film of said coating material adjacent the area where said coating material has been removed is tapered toward a feather edge by the plowing action of said doctoring member. 7

6. An apparatus of the character described comprising a frame, a cylindrical applicator roll mounted in said frame and having a pair of opposed end portions and an axis of rotation, two series of doctor blades carried by said frame, each series of doctor blades being disposed in cont-act with a respective end portion of said roll and having the doctor blades thereof disposed along the length of the respective end portion of said roll, each said doctor blade of each said series being set at an angle to the axis of rotation of said roll, each series of blades being so constructed and arranged that the blades thereof have side portions that overlap adjacent side portions of adjacent blades and are spaced one below the other in stair stepped relation around at least part of said roll, one said series of blades being set 'at an angle to the axis of rotation of said roll so as to move material removed from the surface of one said end portions of said applicator roll to the nearest end thereof, and the second said series of blades being set at a diiferent angle to the axis of rotation of said roll so as to move material removed from the surface of the remaining said end portion of said applicator roll to the nearest end thereof.

7. Apparatus of the character described, comprising a frame, a cylindrical applicator roll mounted in said frame and having a pair of end portions and an axis of rotation, and two series of overlapping and stepwise disposed doctor blades carried by said frame, each series of doctor blades being disposed in contact with a respective end portion of said roll and having the doctor blades thereof disposed along the length of the respective end portion and so oriented angularly with respect to said axis of rotation of said roll as to move coating material respectively toward said respective end portions, whereby said doctor blades sequentially deliver doctored coating material laterally to the zone of a trailing doctor blade, the last doctor blade of each series extending at least to a point closely adjacent the respective end edge of said roll for removing accumulated doctored material from said roll at the respective end edges thereof.

8. An apparatus as set forth in claim 7 wherein each series of doctor blades includes a leading blade, at least one intermediate blade and a trailing blade whereby the coating removed by each blade of each series is transferred to a succeeding blade in the respective series of blades.

9. An apparatus as set forth in claim 8 wherein the trailing doctor blade of each series of blades extends beyond the respectvie end edge of said applicator roll.

References Cited in the file of this patent UNITED STATES PATENTS 1,525,829 Rogers Feb. 10, 1925 2,592,914 Lavett Apr. 15, 1952 2,974,586 Hunt Mar. 14, 1961 FOREIGN PATENTS 608,203 Great Britain Sept. 10, 1948

Claims (1)

1. IN A COATING MACHINE HAVING A CYLINDERICAL ROLL CARRYING A FILM OF FLUID COATING MATERIAL ON THE SURFACE THEREOF, A DOCTORING DEVICE FOR REMOVING SAID COATING MATEIRAL FROM AN END PORTION OF THE SURFACE OF SAID ROLL COMPRISING A DOCTORING MEMBER HAVING A TIP PORTION, THE CENTRAL PART OF WHICH CONTACTS SAID ROLL SURFACES IN A CURVED LINE, SAID MEMBER HAVING PORTIONS FORMING ACUTE ANGLES WITH THEIR PROJECTION ON THE SURFACE OF SAID ROLL WHEREBY THE EDGES OF THE FILM OF COATING MATERIAL ADJACENT THE DOCTORED AREA OF THE ROLL SURFACE ARE TAPERED TOWARD A FEATHER EDGE AND FREE OF THICKENED RIDGES OF SAID COATING MATETIAL.

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