US3264749A

US3264749A - Papermaking drier drum

Info

Publication number: US3264749A
Application number: US325982A
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: 1963-11-26
Publication date: 1966-08-09
Anticipated expiration: 1983-08-09
Also published as: GB955468A

Description

Aug. 9, 1966 PAPERMAKING DRIER DRUM Original Filed April 15. 1959 H. E. MALMSTROM ETAL 5 Sheets-Sheet 1 H. E. MALMSTROM ETAL PAPERMAKING DRIER DRUM Aug. 9, 1966 Original Filed April 15, 1959 5 Sheets-Sheet 2 Aug. 9, 1966 H. E. MALMSTROM ETAL 3,

PAPERMAKING DRIER DRUM 5 Sheets-Sheet 3 Original Filed April 15. 1959 Aug. 9, 1966 H. E. MALMSTROM ETAL 3,264,749

PAPERMAKING DRIER DRUM 5 Sheets-Sheet 4 Orlginal Filed April 15. 1959 @QXQQ \Q m @Qkx wufisq o. m. 8 8 8 mm on Q on xwwiw Q? wxwwkh Qw v Aug. 9, 1966 H. E. MALMSTROM ETAL PAPERMAKING DRIER DRUM Original Filed April 15, 1959 5 Sheets-Sheet 5 093% km w 53 MGEEQQ o m 0- ON mu Om mm Qw m6 om mm co mo 2. 1 2b United States Patent 3,264,749 PAPERMAKING DRIER DRUM Homer E. Malmstrom, Appleton, and Keith C. Martiny, Neenah, Wis., assignors to Kimberly Clark Corporation, Neenah, Wis., a corporation of Delaware Original application Apr. 15, 1959, Ser. No. 806,475, new Patent No. 3,118,743, dated Jan. 21, 1964. Divided and this application Nov. 26, 1963, Ser. No. 325,982 6 Claims. (Cl. 3419) This application is a divisional application with respect to our co-pending application Serial No. 806,475, filed April 15, 1959, for Papermaking Drier Drum (now Patent No. 3,118,743, issued January 21, 1964).

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 ro-ll. 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 off the paper, when dried, from the drier drum. 1

In order to heat the drier drum so that it effectively dries the paper web, steam is introduced at rather high pressures, 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 of the 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.

3,254,749 Patented August 9, 1966 ice 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 the patent 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 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 anda 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 at 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, arrangements, devices and method-s 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:

FIG. 1 is a 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 drum 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;

external drum surface of a conventional drier under two different conditions;

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

FIG.7 is a side elevational view of the drier drum on 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 U 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 10 which rests on a suitable foundation 11 and rotatably supports a drier drum 12. The drier drum includesa generally cylindrical shell 13 having end flanges 14 which.

arebolted 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 oftheshaft 16 with journals 17 which are .rotatably secured in bear ings 18 secured to the frame 10.

The shaft 16 is formed of two hollow axially aligned sections. 19 and 20 which are separated by .a separator plate 21. The separator 21 is provided with a thickened rim 22:,and. a series of openings. 23 extend through the rim and communicate with the interior of the shell 13.

Steam nozzles 24 are threadedinto 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 20. 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 interior t 30:in shaft section 20 to the exterior.

of the shell 13 and discharge the same through the con-. duit 29 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 hood31 is secured to the frame 10 and .extends around the upper portion of the drum 12. Hot air inlets 31a and suitable outlets (not shown) are provided in the hood for the entry and the discharge .of they 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 1 to the frame 10, 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.

blade 40 can be varied, as desired, to obtain the best creping angle.

The doctor blade holder41 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 13.

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 shel1.13. The oscillating motion is provided by an 'eccetk' tric drive shown generally at 49, which isconnec'ted to one of the shafts 42.. The oscillating motion is permitted by aloose fit between the pivot frame 45 Band the frame 10 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 vshell513 may be a single casting, as of castiron, if desired,'and in this case the other parts of the drum 12,

such as theheads15 and shaft 16 are likewise made of cast iron, in order to assure that the complete drumhas the same coefficient,ofthermal-expansion. As an alternative, the shell 13 may be formed of'a pluralityv of plates: 50 which are welded together along their edges, M51 and.

minum, up .to 4 percent'of iron, up to 5 percent of nickel, up to 5 percent of,manganese,.up. to 2 percent oftin, up a to 5 percent of zinc, and the balance being copper,-such as is, for example, disclosed in :the co-pending application of John ,F. Klem-ent, Serial No. 682,577, filed September 9, l957,now-Patent 2,937,965,. issuedMay 24, 1960. In this case, the other, parts of the drum are likewise formed of the same material, and the welds would be'madeiwith substantially the same material also, to assure that the drum as a whole has thesame thermal coefficient 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, vwiththe felt 32 and the .wet': paper web 53 carried on the undersurface of the felt passing. between the roller 34 and the drum 12.1

Thepaper zweb, after. passing between the nip of the roller 34 and drum 12,. passes onto the drum-12 and is dried during rotation of. the drum 12 ;by the time the paper reaches the .creping do'ctor' blade 40.' The blade 40 .crepes the paper. from the drier drum; 12,1 and the paper is wound .on any'suitable rolls (not shown).

The pressure roll 5'34 and .thefldr ier 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,

this being the form of the drum withouta 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 onto the drier'dru m.

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. Ittwill 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 ahi-gh point 55, with the .point 55 being substantially at the edge 56 of the paper web 53 extendingaround. 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 ordinatesand abscissaetshown, are for aparticular drier drum made from the aluminum-bronze alloy, and are illustrative only of one example of drier drum.

Due to the existence ofthe .highjpoint Son 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 ofthe drum 12 than in the. centerportion of the drum. -If the drum .12 is made completely out of 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, is used 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 traveling 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:

The constan s of this equation would of course be different with different dimensions and coefficients 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 Oif 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

59, 60 and 61, all of which are disposed and rotatably supported between opposite parts of the supporting frame 10. An abrasive belt 62 is provided over the

rolls

59, 60 and 61, and the rolls and belt are so positioned between the doctor blade 40 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. Minarik et al. 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 200 degrees; the temperature inside the drum is 287 degrees; and the average tempera- .ture of the shell 13 is 243 degrees.

The cosine curve C may also be ground on the drum 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 origin 58 to the edge 56 of the wet paper Web that would be applied to the drum is as follows:

The drier drum 12 may also be ground at room temperature 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 constants 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 for Y given above except for a constant (.030 for the particular drum considered) indicating the reduction in diameter at the drum center under web drying conditions. The second term b 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 off of the diameter as seen in curve D in this range. 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 64 of a relatively open mesh cloth, similar to cheese cloth, is wound around 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 ontothe 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. 6

operating temperature previously mentioned. The edge portions of the drum, not covered :by the cloth strips 64,

drum to within about '20 inches of the drum ends, permitting the grinding under these simulated operating con-:

diti-ons 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, ,part-icu larly in the .region of the web edges 56, advantageously causes a reduction in wear in the vicinity of these points on the drum. Thisiis particularly true if the drum is madeof a high heatconducting material, such as the aluminumbronze alloy mentioned above, which is relatively soft and has a higher. coeflicien-t of thermal-expansion than cast iron.- If the shell 13 is made of sheets welded-together, the drum contourof the invention results in lessened wear in the regions 57 of the drum surface, The

contours Ca 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 3-2.

It is to be understood that the invention is not to. be limited tov the specific constructions, arrangements, and methods shown and described, except onlyinsofar 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. In -a method of forming the exterior surface of a drier drum, the steps which comprise holding the interior surface of the drum at a certain elevated temperature while holding the exterior surface of the drum in a middle region at a certain reduced temperature with respect to the temperature of end regions of the exterior drum surface, and forming the exterior surface of the drum .while the drum is at said interior and exterior temperatures to crown it from its center to its ends so as to decrease in diameter from its center to its ends.

'2. 'In a method of forming the exterior surface of-a steam heateddrier drum for. a paper machine, the steps which comprise applying steam pressure to .the interior of the drum to hold its interior surfaces at a certain elevated temperature, applying a cooling medium to the. exterior surface of the'drum in a middle region to hold J this portion of the exterior drum surface at a certain reduced temperature with respect to the temperature of end regions of the exterior drum surface, and forming the exterior surface of the drum while the drum is at said interior and exterior temperatures so that the drum; is crowned from its center toward points adjacent the ends of the drumso as to decrease in diameter from its center to said points.

3. In a method of forming the exterior surface of a steam heated drier drum for a paper machine, the steps which comprise applying steam under pressure to the 8% interior of the drum to hold the drum'interiorat a certain elevated temperature, spraying Water onto the ,exterior surface of the drum'to hold the exteriordrum surface at a certain reduced temperature, and abrading the exterior surface of the drum while the drum is'at said ill-1 terior and exterior temperatures so that the drum is crowned from its center toward points adjacent the ends of theydrum soas to graduallydecrease in diameter to said points.

4. In -a method :of forming the exterior surface .of a

steam heated drier drum=for a paper: machine, the steps which comprise applying steam under pressure within said drum to hold its interior'surfacesat a certain elevated temperature, applying a wetwebto the exterior surface; of the drum to hold.the exterior drum :surfaceat acertain :reduced temperature and: abrading the exterior drum surfacewhile the drumis at said interior and exterior temperatures so that the drum is; crowned from its center toward points adjacentthe ends of the .drum so as to decrease in diameter to, said point-s.

Si-Ina method of forming the exterior surfaceof a paper machine drier drum, the stepswhich comprise apa plying steam under pressure within said drum with said drum positioned-in its: usual drying position on a paper. machine, rotating said drum, applying -a wet web of paper to the drum and: traveling it continuously. around thedrum as the drum rotates=to dry the paper and subsequently removing the web from the-drumzwhen'dry, said :paper web when dryingmaintai-ning the exterior surface of the drum. 81:63 certain reduced temperature with respect to the internal. temperature of'thedrum, and abrading the exterior surface of the drum between the point of appli-v cation of the wetzpaperwe'b to .theidrum' and the point of removal of the dried paperweb from the .drumin a mannersothatt-he drum'is crowned from its center. to-' Ward points adjacent the ends of the .drum so as todecrease in diameter to said points from the center of-the drum..

6. -In a method of forming the exterior. surface of a steam heated drierdrum for a paper machine, the steps which comprise, preliminarily crowning the middle portion of the drum so that itsidiameter decreases fromthe 1 center toward the ends, applying a Water absorbing material to the crowned middle portion of the drum, ap-

plying steam under pressure :within said drum to hold,

its internal surfaces at a certain elevate-d temperature, moistening said materialon the exterior crowned drum surface for holding the exterior drumsurfaces at a reduced temperature, and then abrading the exterior drum surfacesnot covered by said material for crowning the end portions of the exteriorzdrum surfaces so that the drum as a whole is crowned from its center toward the.

ends of the drum.

References Cited by the Examiner UNITED STATES PATENTS 1,718,977 7/1929. Overton 34l10 X 2,395,101 2/1946 Case 5l.289 X 2,671,296 3/1954 Geyer 51-289 FREDERICK L. MATTESON,JR., Primary Examiner. WILLIAM 'F.-ODEA, Examiner.

D. A. TAMBURRO, Assistant Examiner.-

Claims

1. IN A METHOD OF FORMING THE EXTERIOR SURFACE OF A DRIER DRUM, THE STEPS WHICH COMPRISE HOLDING THE INTERIOR SURFACE OF THE DRUM AT A CERTAIN ELEVATED TEMPERATURE WHILE HOLDING THE EXTERIOR SURFACE OF THE DRUM IN A MIDDLE REGION AT A CERTAIN REDUCED TEMPERATURE WITH RESPECT TO THE TEMPERATURE OF END REGIONS OF THE EXTERIOR DRUM SURFACE, AND FORMING THE EXTERIOR SURFACE OF THE DRUM WHILE THE DRUM IS AT SAID INTERIOR AND EXTERIOR TEMPERATURES TO CROWN IT FROM ITS CENTER TO ITS END SO AS TO DECREASE IN DIAMETER FROM ITS CENTER TO ITS ENDS.