US3118743A

US3118743A - Papermaking drier drum

Info

Publication number: US3118743A
Application number: US806475A
Authority: US
Inventors: Homer E Malmstrom; Keith C Martiny
Original assignee: Kimberly Clark Corp
Current assignee: Kimberly Clark Corp
Priority date: 1959-04-15
Filing date: 1959-04-15
Publication date: 1964-01-21
Anticipated expiration: 1981-01-21

Description

1964 H. E. MALMSTROM ETAL 3,

PAPERMAKING DRIER DRUM 5 Sheets-Sheet l Filed April 15, 1959 37 Jan. 21, 1964 H. E. MALMSTROM EI'AL 3, 3

PAPERMAKING DRIER DRUM I Filed April 15, 1959 5 Sheets- -Sheet 2 Jan. 21, 1964 H. E. MALMSTROM EI'AL. 3, ,743

PAPERMAKING DRIER DRUM 5 Sheets-Sheet 3 Filed April 15, 1959 @W 7/ m M,

1964 H. E. MALMSTROM ETAL 3, ,743

PAPERMAKING DRIER DRUM Filed April 15, 1959 5 Sheets-Sheet 4 \D a N 40 as pun/v0! ma 1; Of 0012 United States Patent 3,113,743 PAPERMAKING DRER DRUM Homer E. Maiznstrom, Appieton, and Keith C. Mart ny, Neenah, Wis assignors to Kimberly-Clark Corporation, Neenah, Wis, a corporation of Delaware Filed Apr. 15, 1959, Ser. No. 806,475 5 lainis. (Cl. 34-11(5) The invention relates to pressure vessels and more particularly to drier drums for use in the manufacture of paper and to methods of forming the drums.

A papermaking machine of the usual type comprises one or more drier drums which are heated by steam pressure and over which the wet paper web travels after being couched from the forming wire of the paper machine and partially dewatered between felts, being pressed onto the surface of the drums and dried to a desired final moisture content. The more usual paper machines contain a large number of small drier drums between which the paper is transferred while the so called Yankee type paper machine utilizes a single large drier drum on which the wet paper web is dried within a single revolution.

The Yankee drier drums are cast or welded structures and are of considerable size, having a diameter of 8 to 15 feet and a length of 10 to feet, Weighing in the neighborhood of 65 or 70 tons. During operation, the drier drums are subjected to both internal and external pressures. A pressure roll bears against the external surface of the drier drum at the point where the wet paper sheet is first applied to the drier drum, and the pressure roll exerts a force of from 200 pounds to 450 pounds per lineal inch across the entire face length of the drier. Due to this great pressure, the pressure roll deflects; and it is therefore necessary to crown the pressure roll slightly so as to maintain an even pressure across the entire face length of the pressure roll. Due to this bending, the circumferential speed at the center of the pressure roll is greater than at the sides and tends to cause the felt passing between the pressure roll and drier drum to wrinkle out of flat condition, causing uneven wear of the felt. In order to overcome this wear condition, the drier drum is also crowned; and, theoretically, the pressure roll and drier drum are preferably crowned in proportion to their diameters. Practically, the crowning that may be applied to the drier drum is limited, however, due to the fact that a doctor blade rides in contact with the drier drum for the purpose of creping oi the paper, when dried, from the drier drum.

In order to heat the drier drum so that it effectively dries the paper web, steam is introduced at rather high pressure, such as 40 to 60 pounds per square inch, for example, within the drier drum and provides an internal pressure in the drum.

It has been found that, although a conventional drier drum exhibits a proper crowning at the temperature at which it is used, such as at 287 F., at 40 pounds per square inch steam pressure, for example, when a wet paper web is applied onto the drier drum, the drum loses its optimum crowning and has high points at its ends, due to the fact that the wet paper Web maintains the surface ofvthe drum covered by the web at a lower temperature than the temperature of the steam supplied to the drum while the edges of the drum progressively increase in temperature toward the drum ends. Due to the existence of these high points, the doctor blade scraping the dried paper web from the drier drum causes excessive wear of the drum at its ends.

Yankee drier drums are generally made of cast iron, and exhibit wear to a noticeable extent at the ends of the drum due to the scraping action of the doctor blade, so

"ice

that the drums must be reground after 9 months or one year of usage. Yankee drier drums may also be made of other better heat conducting materials, such as aluminum-bronze alloys, and such drier drums wear to a greater extent, due to the fact that, although such alloys conduct heat better than cast iron and are thus more suitable in this respect, they are softer and thus wear easier under doctor blade action. Also, such alloys have a greater coefficient of thermal expansion than cast iron, and drums of such alloys thus become more out of shape than do cast iron drums and wear more for this reason also.

This wearing action of the doctor blade on the ends of the drum surface is still more pronounced when the drum surface is made from sheets of aluminum bronze alloy welded together in a manner such as is described, for example, in a co-pending application of C. G. R. Johnson, Serial No. 699,704, filed November 29, 1957, now Patent 3,052,039, issued September 4, 1962. With such a construction, the drum has been found to wear in particular just behind the welds joining the plates together, adjacent the side edges of the drum.

It is an object of the present invention to provide an improved drier drum having a crowned outer surface presenting no ridges adjacent the edges of the drum subject to undue wear by the doctor blade, under the conditions of usage of the drum, namely, when steam is applied to the drum for heating it and a wet paper web extends around the drum within short distances of the drum ends for drying the web.

It is another object of the invention to provide an improved drier drum of this type which, when an uniform temperature, is gradually crowned along most of its length and is more severely crowned or tapered adjacent the ends of the drum, with the drum being at uniform temperature, so that when the drum has a web of wet paper applied to it and steam is supplied to it, the drum exhibits a proper crowning, nearly in a straight line from each end to the middle of the drum.

It is a more specific object of the invention to provide such an improved crowning outline on a drum made from a material that is better heat conducting but softer than cast iron, such as aluminum-bronze previously mentioned, particularly in which the drum is made up of a plurality of sheets of this material welded together.

It is also an object of the invention to provide improved methods for forming drums having the outline previously referred to, having no end ridges subject to undue wear by the doctor blade under operating conditions of the drum.

The invention consists of the novel constructions, ar-

rangemen-ts, devices and methods to be hereinafter described and claimed for carrying out the above stated objects and such other objects, as will be apparent from the following description of a preferred form of the invention and methods for making the same, illustrated with reference to the accompanying drawings, wherein:

P16. 1 is fragmentary side elevational view of a paper machine incorporating a drier drum embodying the principles of the invention;

FIG. 2 is a fragmentary end View on an enlarged scale of the drier dnum shown in FIG. 1;

FIG. 3 is a longitudinal sectional view on a reduced scale of the drier drum;

FIG. 4 is a perspective view of the outer cylindrical shell of the drier drum;

FIG. 5 is a graphical illustration of the contour of the external drum surface of a conventional drier under two different conditions;

FIG. 6 is an illustration similar to FIG. 5 but of the improved drier drum contour of the present invention;

FIG. 7 is a side elevational view of the drier drum on 30 in shaft section 2i! to the exterior.

a reduced scale showing a plurality of water showers applied to the drum for reducing the external temperature thereof in grinding the external drum surface; and

FIG. 8 is a view similar to FIG. 7 showing a cooling fabric applied to the drum during the grinding operation.

Like characters of reference designate like parts in the several views.

Referring now to the drawings, the Yankee type paper machine illustrated comprises a supporting frame 16 which rests on a suitable foundation 1.1 and rotatably supports a drier drum 12. The drier drum includes a generally cylindrical shell 13 having end flanges 14 which are bolted to heads 15. The heads 15 enclose the ends of the shell and are provided with aligned axial openings which receive a hollow shaft 16. The drier drum is mounted for rotation by providing the ends of the shaft 16 with journals 17 which are rotatably secured in bearings 18 secured to the frame 10.

The shaft 16 is formed of two hollow axially aligned sections 19 and 243' which are separated by a separator plate 21. The separator 21 is provided with a thickened rim 22, and a series of openings 23v extend through the rim and communicate with the interior of the shell 13. Steam nozzles 24 are threaded into the openings 23 and serve to distribute steam from the interior 25 of the shaft section 19 to the interior of the shell 13. A pair of scoops 26 are secured to the ends of pipes 27 which extend radially through openings 28 in the shaft section 2%. The inner ends of the pipes 27 are connected to a conduit 29 which extends outwardly through the passage The scoops 26 serve to scoop out the steam condensate from the interlor of the shell :13 and discharge the same through the conduit 2? to the exterior.

The drier drum .12 is rotated by a conventional drive mechanism, not shown, which is attached to the end of the shaft 16 by a suitable gear or pulley arrangement.

A heating hood 31 is secured to the frame 10 and extends around the upper portion of the dnum 12. Hot air inlets 31a and suitable outlets (not shown) are provided in the hood for the entry and the discharge of the air or other heating medium applied to the hood.

The wet paper web to be dried is carried by a felt web 32 which travels around felt rolls 33. The paper web is forced against the surface of the drier shell 13 by a pressure roller 34 which is rotatably mounted in brackets 35 secured to an arm 36. The arm 36 is pivoted at 37 to the frame 16, and the pressure roller 34 is forced against the surface of the drier shell 13 by a ram 38 of a hydraulic cylinder 39 which bears against the arm. 36.

The dried paper web is removed from the. surface of the drier shell by a creping doctor, which includes a doctor blade 40 removably secured within a doctor blade holder 41. The ends of the holder 41 are provided with shafts 42 which are rotatably mounted within guide blocks 43. The blocks '43, in turn, are each slidably mounted within a slide assembly 44 attached to pivot frame 45 pivotally carried by the frame 10. Through the slide arrangement provided by the guide blocks 43 and the slide assembly 44, the vertical position of the doctor blade 40 can be varied, as desired, to obtain the best creping angle.

The doctor blade holder 41 and the blade 40 are pivoted by a toggle mechanism 46 which is attached through a lever arm 47 to one of the shafts 42. In addition, a spring loading mechanism 48 is connected through the toggle mechanism 46 to provide a resilient contact for the doctor blade against the surface of the drier shell 113.

In addition to the vertical and pivotal adjustment for the doctor blade 40, the doctor blade is adapted to oscillate in a direction generally parallel to the axis of the shell 13. The oscillating motion is provided by an cecentric drive shown generally at 49, which is connected to one of the shafts 42. The oscillating motion is permitted by a loose fit between the pivot frame 45 and the frame 19 and permits the doctor blade to move back and forth across the shell surface as the shell 13 rotates, to prevent uneven wear of the doctor blade and of the drier drum during operation.

The shell 13 may be a single casting, as of cast iron, if desired, and in this case the other parts of the drum 12, such as the heads 15 and shaft 16 are likewise made of cast iron, in order to assure that the complete drum has the same coefiicient of thermal-expansion. As an alternative, the shell 13 may be formed of a plurality of plates 50 which are welded together along their edges, at 51 and 52, as seen in FIG. 4. This construction is particularly suitable if an alloy having a high heat conductivity, as compared to cast iron, is used, such as an aluminumbronze alloy, having, for example, up to 8 percent of aluminum, up to 4 percent of iron, up to 5 percent of nickel, up to 5 percent of manganese, up to 2 percent of tin, up to 5 percent of zinc, and the balance being copper, such as is, for example, disclosed in the copending application of John F. Klement, Serial No. 682,577, filed September 9, 1957, now Patent 2,937,965, issued May 24, 1960. In this case, the other parts of the drum are likewise formed of the same material, and the welds would be made with substantially the same material also, to assure that the drum as a whole has the same thermal coeflicient of expansion.

In operation, the drum 12 is driven from any suitable power source; and the pressure roller 25, rotatably mounted on the brackets 35, rotates, with the felt 32 and the wet paper web 53 carried on the under surface of the felt passing between the roller 34 and the drum 12. The paper web, after passing between the nip of the roller 34 and drum 12, passes on to the drum 12 and is dried during rotation of the drum 12 by the time the paper reaches the creping doctor blade 40. The blade 40 crepes the paper from the drier drum 12, and the paper is wound on any suitable rolls (not shown).

The pressure roll 34 and the drier drum 12 have customarily been crowned for reasons which have been hereinbefore mentioned. Assuming that the drier drum 12 is operated at 40 pounds per square inch steam pressure, for example, the crowning of the drier drum has been approximately in the form shown by curve A in FIG. 5, 7

this being in the form of the drum without a web of paper on the drum and at the operating steam pressure. Under these conditions, it will be understood that the temperature throughout the drier drum is uniform. It has been found that when a wet paper sheet is applied on to the drier drum when the drum is in use, the drum is distorted so that the drum has an exterior surface substantially in the form shown by curve B of FIG. 5. It will be noted that the drum surface as a whole has decreased in diameter and that the drum surface increases in diameter from a low point 54 to a high point 55, with the point 55 being substantially at the edge 56 of the paper web 53 extending around and being dried by the drum. The contour curves A and B, as well as the curves C and D in FIG. 6, to be subsequently referred to, with reference to the particular values of ordinates and abscissae shown, are for a particular drier drum made from the aluminumbronze alloy, and are illustrative only of one example of drier drum.

Due to the existence of the high point 55 on each edge of the drier drum, it has been found that the doctor blade 40 causes a substantially greater amount of wear at the ends of the drum 12 than in the center portion of the drum. If the drum 12 is made completely out of the cast iron, the increased wear of the drum at the ends as contrasted to the center portion of the drum necessitates a regrinding of the drum, generally speaking, for every six months or nine months of usage. In the event a softer material, such as an aluminum-bronze alloy, as previously mentioned, isused for the shell 13, the wear is noticeable much sooner, and assuming the shell 13 is made from a plurality of sheets of this material welded together as shown in FIG. 4, the wearing action is particularly noticeable in areas 57 (see FIG. 2) adjacent to and lying just behind the welds 52 and adjacent the edges 56 of the paper web 53. The formation of such unduly worn areas 57 necessitates the regrinding of the softer drum after much shorter periods of usage.

The present invention contemplates the provision of an outer shell surface on the drum 12 which does not include the high points 55 adjacent the edges but rather a surface which gradually increases in diameter to the drum center from the drum edges, this contour to exist under actual operating conditions, with the operating steam pressure (such as 40 pounds per square inch) applied within the drum and with the Web of wet paper travelling around the drum. The shape of the shell may be in the form shown by curve C in FIG. 6, for example. Preferably the shape of this curve, from the edge of the paper web at 56 to the center of the drum, is of cosine form. For a particular drum, the equation for the curve C is as follows:

.030 .Olo [cos L /1 1] The constants of this equation would of course be different with different dimensions and coefiicients of thermalexpansion of different materials used. The term is in degrees. The constant .030 is the measurement in inches of the reduction of diameter at the center of the drum 12 that occurs when the sheet is applied. Both Y and X are measured in inches from an origin 58. The X term is the distance in inches from the center of the drum measured until the point 56 at the edge of the paper web is reached, and the term L is the length of the face of the drier in inches measured to the point 56, the width of the sheet being 128 inches for example. As will be observed from the equation, the cosine term, when X is zero, equals unity, so that the part of the equation in brackets is zero, whereby the reduction in diameter of the drum at its center of .030 inch is indicated. From the paper edges 56 to the adjacent edges of the drum, the drum is dubbed or reduced in diameter more sharply than curve C, since this is outside the paper drying area.

The drier drum 12 may be ground into the form indicated by curve C of FIG. 6 by using conventional grinding mechanism, such as that shown in the patent to R. G. Minarik et al., No. 2,579,391, issued December 18, 1951. The grinding equipment may be used on the drum 12 when the paper machine is in actual operation, if desired, such as shown in FIG. 1. The grinding equipment may comprise rolls 5?, 6t) and 61, all or which are disposed and rotatably supported between opposite parts of the supporting frame it An abrasive belt 62 is provided over the

rolls

59, 6d and 61, and the rolls and belt are so positioned between the doctor blade 4% and the pressure roll 34 that the abrasive belt 62 grinds the surface of the drum 12 when the paper machine is in operation. The belt 62 may be driven and may be guided so as to form the curve C on the exterior surface of the drum 12 by the mechanism shown in the R. G. lvlinarik patent. The web of paper passing around the drum 12, under these conditions, maintains the exterior surface of the drum between the points 56 below the temperature of the steam pressure supplied to the drum. For a particular aluminum-bronze drum 12, and for a 40 pounds per square inch steam operating pressure, the exterior surface of the drum between the points 56 is maintained by the wet paper web at about 260 degrees; the temperature inside the drum is 287 degrees; and the average temperature of the shell 13 is 243 degrees.

The cosine curve C may also be ground on the drum the diameter as seen in curve D in this range.

under simulated operating conditions as shown in FIG. 7 by directing a plurality of water sprays 63 onto the surface of the drum between the points 56 so as to maintain the outside temperature of the drum at the operating temperature with the wet paper web applied to it, which in the above mentioned case is 200 degrees. With the sprays of water thus directed on the drum, the drum is ground in a conventional manner, such as with the

rolls

59, 60 and 61 and abrasive belt 62 to have the desired contour.

The drum may also be ground when it is at a uniform temperature such as the temperature corresponding to the operating steam pressure of 40 pounds per square inch. At this time it is not cooled on its external surface by means of the water sprays or wet paper web. Since the outer edge portions of the drum can be expected to be too high, the edge portions are ground down to a smaller diameter than would be expected from the curve C. In particular, the drum may be ground under these conditions to have a surface as shown by the curve D as seen in FIG. 6 which has been found to result in the surface contour C when the drum is used under actual operating conditions with the paper web passing over and being dried by the drum. For the particular drum hereinbefore mentioned, the equation for the curve D from the origi 53 to the edge 56 of the wet paper web that would be applied to the drum, is as follows:

(a) {.015 [cos The drier drum 12 may also be ground at room tem perature into proper shape, so that it has the ultimate shape as shown by curve C under operating conditions, The proper contour of the drum 12 at room temperature is much like the curve D and is defined by an equation such as that for Y given above, except that the con stants are different.

With respect to the relative importance of the various terms of the value for Y given above, it may be stated that the term a is relatively the most important in the middle part of the drum, that is, from approximately 20 inches inwardly from each end of the drum toward the middle. This is the same as the value or Y given above except for a constant (.030 for the particular drum considered) indicating the reduction in diameter at the drum cent r under Web drying conditions. The second term [7 of the equation for Y becomes the most important term between 6 inches and 20 inches inwardly from each end of the drum which is reflected by the sharp drop olf of Between zero and 6 inches inwardly from each end of the drum, the drum is dubbed to further decrease the likelihood of doctor blade wear at the extreme ends of the drum 12.

The drum may also be ground to the desired surface contour under other simulated operating conditions, such as shown in FIG. 8. In this case a strip or puttee as of a relatively open mesh cloth, similar to cheese cloth, is wound around the drum 12 within about 20 inches of the edges of the drum. The middle portion of the drum covered by the cloth strip has been previously ground into conventional shape as shown by the curve A of FIG. 5, which approximates curve D from the center of the drum to within 20 inches of each edge. Water showers 63 are then sprayed onto the cloth strip 64, so that the cloth maintains the external surface of the drum toward the edges of the drum in the vicinity of the 200 degrees operating temperature previously mentioned. The edge portions of the drum, not covered by the cloth strips 64, are then ground, using for example the rolls 59, 6t) and 61 and abrasive belt 62, so as to have the contour shown by curve C of FIG. 6 in this range. As is apparent from the above discussion of curves C and D, for the particular drum under consideration, the curve D under operating steam pressure approximately results in the curve C when the paper web is applied from the middle of the drum to Within about 20 inches of the drum ends, per initting the grinding under these simulated operating conditions to give an approximately correct contour.

Regardless of which method is utilized for forming the external surface on the drum as shown by the curve C, the reduction in diameter at the drum ends, particularly in the region of the web edges 56, advantageously causes a reduction in wear in the vicinity of these points on the drum. This is particularly true if the drum is made of a high heat conducting material, such as the aluminum bronze alloy mentioned above, which is relatively soft and has a higher coefiicient of thermal-expansion than cast iron. If the shell 13 is made of sheets welded together, the drum contour of the invention results in lessened wear in the regions 57 of the drum surface. The contours C and D also provide a more even pressure on the drum surface from the pressure roll 34 resulting in more even wear of the felt 32.

it is to be understood that the invention is not to be limited to the specific constructions, arrangements and methods shown and described, except only insofar as the claims may be so limited, as it will be understood to those skilled in the art that changes may be made without departing from the principles of the invention.

What is claimed is:

1. A drier drum adapted to have a heated fiuid under pressure supplied to it for heating the drum for drying a web or" sheet material on the drum periphery and comprising a generally cylindrical drier shell for receiving the web; said shell under the pressure of said heated fiuid decreasing in diameter from the center of the shell to the shell ends with the profile of the shell in a relatively long central zone, which extends for the major portion of the length of the shell, being a relatively gradual curve and the profile of the shell in substantially shorter intermediate zones on the ends of said central zone, which extend for minor portions of the length of the shell, being curves which are substantially sharper than the curve defining the profile of said central zone and the shell in still shorter end zones decreasing in diameter substantially more abruptly toward the shell ends than in said intermediate and central zones.

2. A drier drum adapted to have steam under pressure supplied to it for drying on its periphery a Web of sheet material having a width of a predetermined dimension and the drum comprising a generally cylindrical drier shell and heads for enclosing the ends of the shell and supporting the shell; said shell under steam pressure decreasing in diameter from the center of the shell to the shell ends with the profile of the shell in a relatively long central zone, which is within said dimension and extends for the major portion of the length of the shell, being a relatively gradual curve and the profile of the shell in shorter intermediate zones on the ends of said central zone, which with said central zone complete said dimension and extend for minor portions of the length of the shell, being curves that are substantially sharper than the curve defining the profile of said central zone and the shell in still shorter end zones outside of said dimension decreasing in diameter substantially more abruptly toward the shell ends than in said intermediate and central zones.

3. A drier drum adapted to have steam under pressure supplied to it for drying at web of sheet material on the drum periphery and comprising a generally cylindrical drier shell and heads for enclosing the ends of the shell and supporting the shell, said shell under steam pressure decreasing in diameter from the center of the shell to the shell with the profile of the shell in a relatively long central zone being a relatively gradual curve and the profile of the shell in shorter intermediate zones on the ends of said central Zone being curves that are substantially sharper than the curve defining the profile of said central zone and the shell in still shorter end zones decreasing in diameter substantially more abruptly toward the shell ends than in said intermediate and central zones; said intermediate zones encompassing minor portions of the length of the shell and said central zone encompassing the major portion or" the length of the shell that is several times longer than the lengths of said intermediate zones taken together.

4. A drier drum adapted to have steam under pressure supplied to it for drying on its periphery a web of sheet material having a width of a predetermined dimension and the drum comprising a generally cylindrical drier shell and heads for enclosing the ends of the shell and supporting the shell; said shell under steam pressure decreasing in diameter from the center of the shell to the shell ends with the profile of the shell in a relatively long central zone, which is within said dimension and extends for the major part of the length of the shell to about 20 inches from the ends of the shelhbeing a relatively gradual curve and the profile of the shell in shorter intermediate zones on the ends of said central zone, which with said central zone complete said dimension and extend for minor portions of the length of the shell, being curves that are substantially sharper than the curve defining the profile of said central zone and the shell in still shorter end zones outside of said dimension decreasing in diameter substantially more abruptly toward the shell ends than in said intermediate and central zones; the length of the shell encompassed by said central zone being several times the length of the shell encompassed by said two intermediate zones taken together.

5. A drier drum adapted to have steam under pressure supplied to it for drying a web of sheet material on the drum periphery and comprising a gene ally cylindrical drier shell of an aluminum bronze alloy and heads for enclosing the ends of the shell and supporting the shell; said shell under steam pressure of approximately 40 pounds per square inch decreasing in diameter from the center of the shell to the shell ends with the profile of the shell in a relatively long central zone, which extends for the major portion of the length of the shell, being a relatively gradual curve and the profile of the shell in shorter intermediate zones on the ends or" said central zone, which extendfor minor portions of the length of the shell, being curves that are substantially sharper than the curve defining the profile of said central zone and the shell in still shorter end zones decreasing in diameter substantially more abruptly toward the shell ends than in said intermediate and central zones; said end zones extending from the ends of said shell and encompassing about six inches of the shell length and said central zone extending to approximately 20 inches from the ends of the shell and encompassing a length of the shell which is several times the length of the shell encompassed by said intermediate zones taken together.

References ited in the file of this patent UNITED STATES PATENTS 243,615 Piper June 28, 1881 1,718,977 Overton July 2, 1929 1,779,467 Einstein Oct. 28, 1930 2,033,324 Caster et al Mar. 10, 1936 2,519,105 Blue Aug. 15, 1950 2,779,104 Sims Ian. 29, 1957 2,817,908 Hornboster new??? Dec. 31, 1.957

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noe 1x 118 743 January 21 1964 Homer Ea Malmstrom et al@ It is hereby certified that error a ppears in the above numbered patent requiring correction and that the sa id Letters Patent should read as corrected below.

Column 2, line 31 for "an" read me at =5 column 4,, line 46 strike out "in; column 6 line 48 for "or" read for Signed and sealed this 16th day of June 1964,

(SEAL) Attest:

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

Claims

1. A DRIER DRUM ADAPTED TO HAVE A HEATED FLUID UNDER PRESSURE SUPPLIED TO IT FOR HEATING THE DRUM FOR DRYING A WEB OF SHEET MATERIAL ON THE DRUM PERIPHERY AND COMPRISING A GENERALLY CYLINDRICAL DRIER SHELL FOR RECEIVING THE WEB; SAID SHELL UNDER THE PRESSURE OF SAID HEATED FLUID DECREASING IN DIAMETER FROM THE CENTER OF THE SHELL TO THE SHELL ENDS WITH THE PROFILE OF THE SHELL IN A RELATIVELY LONG CENTRAL ZONE, WHICH EXTENDS FOR THE MAJOR PORTION OF THE LENGTH OF THE SHELL, BEING A RELATIVELY GRADUAL CURVE AND THE PROFILE OF THE SHELL IN SUBSTANTIALLY SHORTER INTERMEDIATE ZONES ON THE ENDS OF SAID CENTRAL ZONE, WHICH EXTEND FOR MINOR PORTIONS OF THE LENGTH OF THE SHELL, BEING CURVES WHICH ARE SUBSTANTIALLY SHARPER THAN THE CURVE DEFINING THE PROFILE OF SAID CENTRAL ZONE AND THE SHELL IN STILL SHORTER END ZONES DECREASING IN DIAMETER SUBSTANTIALLY MORE ABRUPTLY TOWARD THE SHELL ENDS THAN IN SAID INTERMEDIATE AND CENTRAL ZONES.