US3151953A - Belt conveying arrangement in paper drying machine - Google Patents

Description

Oct. 6, 1964 E. .1. JUSTUS 3,151,953

BELT CONVEYING ARRANGEMENT IN PAPER DRYING MACHINE Filed Dec. 23, 1960 2 Sheets-Sheet 1 r I r 2* i l 1 P /6c mp l' I J I [1 My, INVENTOR.

5 Edgar c/. dash/s /7 /4 /4 9 W IZ-0W ATTORNEYS I Oct. 6, 1964 E. J. JUSTUS 3,151,953

BELT CONVEYING ARRANGEMENT IN PAPER DRYING MACHINE Filed Dec. 23, 1960 2 Sheets-Sheet 2 l I i 1,p 1 40/ I i I I L l i I I F l E I i P-a I I 4&4/

I 1 g I l l L. l I l i i P-b I 405 l 7' 1 y 4 3 4/ E a M ]N VEN TOR.

Edg or d. clusfas A TTORNE YS United States Patent 3,151,953 BELT CQN Vh YING AREANGEP/ENI m FAPER DRYMG MACH E Edgar I. Justus, Beioit, Win, assignor to Beloit Iron Works, Beloit, Wis, a corporation of Wisconsin Filed Dec. 23, 1969, Ser. No. 77,96i3 1 Claim. ((31. 34-118) The instant invention relates to drying means, and more particularly, to a paper machine dryer arrangement.

Although the instant invention may have use in a number of devices involving the drying of material conveyed on a traveling drying surface and covered with a drying control means such as a paper machine felt, the instant invention is particularly adapted to the paper machine dryer art and will be described primarily in connection therewith. In a conventional paper machine dryer there is ordinarily provided a moving drying surface carrying the Web, and this drying surface is heated so as to effect drying of the paper web. The heating surface may be that of a large Yankee dryer drum, or it may be the heating surface of one of a plurality of dryer drums of conventional size. These latter dryer drums are ordinarily arranged in a pair of upper and lower tiers, with the paper web traveling a serpentine path first around the bottom of one of the drums in the lower tier and then back up over the top of the adjacent drum in the upper tier, then back down around the adjacent drum of the lower tier, and so on. In this arrangement, or in the Yankee dryer drum arrangement, it is conventional to cover substantially the full width of the web on such drying surfaces with a drying felt. The drying felt in each case travels with the web and in contact therewith and presses the Web against the drying surface, so as to control to a certain extent the drying of the web in a number of ways, including removal of water from the web into the felt, urging the web against the dryer drum for better heating of the moisture in the web to evaporate the same, providing a permeable (felt) member for controlling the rate of evaporation, etc. The factors involved in paper web drying are numerous and quite complicated in presentday paper making equipment.

One of the problems which has presented a number of difficulties to the industry is the tendency for the edges of the traveling paper Web to dry too rapidly or to too great an extent. Many solutions to this problem have been proposed and some of those proposed have found at least limited commercial acceptance. But in many cases this situation leaves much to be desired. The instant invention affords a unique solution to the problem of non-uniform drying in laterally divided portions of the traveling web. As used herein, the term longitudinal has reference to the direction of travel of the web, the drying surface carrying the web, and the felt means covering the web; Whereas the term lateral has reference to the transverse direction with respect to the direction of travel. The edges of the traveling web are, of course, laterally spaced from each other and may be considered laterally divided from the central web portions (although all of such web portions are merely parts of a single unitary traveling web).

The instant invention affords a solution to the problem by the use of separate and independent means for applying variable pressures against the web via portions of the felt means divided laterally of the direction of travel. In other words, the instant invention provides felt means covering the web either in the form or" a plurality of separate and distinct laterally arranged contiguous felt elements, or in the form of a conventional drying felt backed by a plurality of laterally arranged contiguous looped belts, in an arrangement wherein separate and ice independent means may apply variable pressures to laterally divided web portions via such laterally arranged contiguous felt or belt components. In such an arrangement, for example, central portions of the web may be pressed to a greater extent against the hot drying surface to accelerate drying thereof, so that the overall drying rate of the central portions of the web will approximate the normally faster drying rate of the edge portions.

It is, therefore, an important object of the instant invention to provide an improved drying device, and more particularly, an improved drying arrangement for a traveling paper web.

It is another object of the instant invention to provide, in a paper web drying device, a moving drying surface carrying the web in a given direction, felt means covering the web and traveling therewith, and separate and independent means for applying variable pressures against the web via portions of said felt means divided laterally or" the direction of travel.

Other and further objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed disclosure thereof and the drawings attached hereto and made a part hereof.

On the drawings:

FIGURE 1 is an essentially diagrammatic elevational view of a portion of a paper machine dryer employing an embodiment of the instant invention;

FIGURE 2 is essentially a top plan view of the embodiment of FIGURE 1 taken substantially along the line IIII of FIGURE 1;

FIGURE 3 is an essentially diagrammatic side elevational view of a portion of a paper machine dryer showing another embodiment of the instant invention; and

FIGURE 4 is essentially a top plan view taken substantially along the line IVIV of FIGURE 3.

As shown on the drawings:

In FIGURE 1 there is shown a portion of a paper machine dryer indicated generally by the reference numeral lit. The paper machine dryer comprises a lower tier of steam heated dryer drums 11, 12, 13 and an upper tier of steam heated dryer drums 14 and 15. The moist paper web W travels in a generally serpentine path (indicated by the arrows) in contact with and down around the bottom of the first dryer drum 11 of the bottom tier and then upwardly and over the top of the first dryer drum .4 of the upper tier, and so on. While the web W is in contact with the dryer drums 11 through 15, it is heated and the moisture therein is caused to evaporate. The dryer drum 14, for example, provides a moving smooth drying surface 14a which contacts the web W and carries the same in the direction of travel of the dryer drum 14. The dryer drum surface is conventionally made of polished metal which transmits heat rapidly and efiectively from the steam heated interior of the dryer drum 14.

While the web W is traveling in contact with the drying surface 14a, it is covered with a conventional drying felt 16, maintained in position by guide rolls 17 and 18. In like manner, while the Web W travels along in contact with :the moving drying surface 15a of the upper dryer drum 15, it is also covered across substantially the entire width thereof by the dryer felt 16, which is maintained in position for this purpose by guide rolls 18 and 19. To the extent described, FIGURE 1 represents a conventional paper machine dryer arrangement. The felt 16 travels through a complete loop (not shown) in a conventional manner, during which it may be dried, pressed, cleaned, etc. while it is not in contact with the web W. Also, the dryer arrangement itself will ordinarily comprise a very substantial number of dryer drums in the lower tier (in addition to the drums 11, 12 and 13) and in the upper tier (in addition to the drums 14 and 15). Ordinarily, a single looped dryer felt, such as the felt 16 will be employed in conjunction with only a portion of the dryer drums-in a, given tier, and other felts (not shown) will be employed in conjunction with other dryer drums in the same tier. As here shown, however, the same felt 16 is employed with the two upper dryer drums 14 and 1 5 in a device embodying the invention which comprises separate and independent means (indicated generally by the reference numeral 20) for applying variable pressures against the web W via portions of the felt means 16 divided laterally of the direction of travel.

As indicated in FIGURE 2, the traveling dryer felt 16 is a unitary element which may be assumed to be divided into edge portions 16a and 16b and central portions 160 and 16d (as indicated generally along the left hand margin of FIGURE 2). The pressure applying means indicated generally at 29 comprise a plurality of laterally arranged contiguous looped belts 20a, 20b, 20c and 20d, as indicated in FIGURE 1, the belts 20a and 20b are looped belts having within their loops the previously mentioned felt guide roll 18, plus two additional guide rolls 21 and 22 and a tensioning roll 23, provided with conventional variable positioning means indicated diagrammatically at 24 for movement of the tensioning roll 23 so as to effect variable tension throughout the loop of the belts 20a and 20b. It will be appreciated that a separate tensioning roll could be provided for each of the individual belts 20a and 20b mounted in approximately the location of the instant tensioning roll 23, but in the embodiment here indicated, the belts 20a and 20b may be adjusted to substantially the same tension during use (since their uses with respect to the two edges of the web W are similar).

In addition, the centrally disposed belt members 200 and 200! are looped belts having within their loops the previously mentioned felt guide roll 18, the addiitonal belt guide rolls 21 and 22, and a tensioning roll 25 provided with adjustable positioning means indicated generally at 26 for variably adjusting the tension in the belts 20c and 20d. Again, it will be appreciated that instead of the tensioning roll 25, separate and distinct tensioning rolls (not shown) located in approximately the same position may be provided for each of the two belts 20c and 20d. Since, however, the two belts 20c and 20d are intended for use in the application of variable pressures against the central portions of the web W in this particular embodiment, it has been found desirable to use the same tensioning means 25, 26 for both. It will be appreciated that the tensioning rolls 23 and 25 are separate and independent means for applying variable pressures against the web via separate and independent belts (for example, the belts 20a and 200) As indicated in the broken-away portion at the upper right hand corner of FIGURE 2, the traveling web W has an edge portion Wa traveling in contact with the moving drying surface 15a of the dryer drum 15. This edge portion Wa is covered by an edge portion 16a of the unitary dryer felt 16, which in turn is covered by the traveling belt 26a under tension by virtue of the variable tension roll 23. Varying the position of the tensioning roll 23 effects variation in the pressure applied against the edge portion We of the web W and thus affects the rate of drying thereof. In a typical example, the pressure applied to the edge portion Wa of the web is less than that applied to the central portions of the web (via the belts 20c and 20d) so that the drying effect on the edge portion Wa that is caused solely by pressing the same against the dryer drum surface 15a will be less and the drying effect caused by pressing of the interior portions of the web W against the drum surface 15a may be greater (as a result of the use of greater tensions in the belts 20c and 20d). The total drying effect, or actual rate of drying between the interior and the edge portions of the Web W is, of course, notrdirectly responsive to the pressure applied to the web against the drying surface, since numerous other factors including the circulation of dry air and the like are involved. There is, however, a tendency for drier air to be available in the region of the edge portions Wa, so that drying ordinarily takes place faster along the edge portions. The instant invention affords a means of compensating for this variation in drying rate. 7

It will be appreciated that the drying felt 16 may be of conventional drying fel-t texture, which permits absorption of water from the web and/ or permeation by evaporated moisture. The belts 20a through 20d are preferably also made of substantially the same drying felt texture. It will be appreciated that by varying the texture of the belts 20a through 20d differences may also be obtained in certain aspects of the overall drying phenomena. The instant invention, however, affords separate and independent means for applying variable pressures across the width of the web W so as to afford selective control of the drying effect resulting primarily from the pressing of the moist Web against the hot drying surface.

It will be noted that the belts 20a through 20d are contiguous in the sense that they provide continuously controlled pressure applying means across the entire width of the felt (and, of course, across the entire width of the Web W). As here shown, the belts 20:: through 29d are touching, so that there will not be any non-pressure areas therebetween. To avoid any tendency for relaxation in the pressure applied along edges of the individual belts 26a through 20d, it may be desirable to reinforce the edges so that they may accomplish the desired result merely by touching each other as shown in FIGURE 2. Or it may be necessary to employ a slight overlap, as indicated in the subsequent embodiment, in which case a different belt guide roll arrangement is provided, using an arrangement of the type shown in FIGURES 3 and 4.

Referring now to FIGURE 3, it will be seen that there is shown a second paper machine dryer arrangement comprising an upper tier of rolls 31, 32, etc. and a lower tier or rolls 33, 34-, 35, etc. with a paper web P again following a serpentine path down around the bottom of a first dryer drum 33 in the lower tier and upwardly and over the top of the next dryer drum 31 in the upper tier, and so on. The web P is a unitary element, which may be divided laterally into edge portions Pa and Pb, and a central portion P0.

In the instant arrangement there are provided laterally arranged contiguous felt portions a, 40b and 400 covering the full width of the traveling web P and traveling therewith (with the individual felts 40a, 40b and 400 covering respectively the laterally divided portions of the web Pa, Pb and P0, respectively).

As indicated in FIGURE 3, the central felt 400 is mounted on a plurality of guide rolls 41, 42, 43, 44, and 46 and is also provided with a separate and independent tensioning roll 47 with adjustable positioning means indicated generally at 48 for effecting variation in the tension in the felt 49c. This variation in the tension in the felt 46c effects a variation in the pressure forcing the central portion P0 of the web P against the heated moving drying surfaces 33a, 34a and 35a of the dryer drums 33, 34 and 35.

Since the outer felts 45a and 40b overlap the central felt 400 (as indicated in FIGURE 4), the central felt 460 is mounted in an interior loop as indicated in FIG- URE 3, and the outer felts 49a and 40b are mounted in exterior loops. As indicated in FIGURE 3, the outer felt40b which covers an edge portion Pb of the web P is mounted on felt guide rolls 41, 42, 43, 44, 49, 50 and 51, and is provided with a tensioning roll 52 equipped with a variable positioning means indicated generally at 53 for varying the tension in the felt 49b.

The other edge felt 40a, covering the edge portion Pa of the web P is also mounted on felt guide rolls 41,

42, 43, 44, 49, 50 and 51, but a separate and independent tensioning roll 54 is provided therefor with an adjustable positioning means indicated generally at 55. The use of the separate and independent tensioning rolls 52 and 54 for the felts 40b and 40a, respectively, permits variations in the pressure applied to the edge portions Pa and Pb to correct for circumstances tending to cause more rapid drying at one of the other edges of the web P. This situation can occur, for example, when the air circulation to the dryers is different at the front and back sides of the machines.

In the embodiment of FIGURES 3 and 4 the felt means 40a through 400 effectively cover the entire width of the Web P, although such felt means comprise a plurality of laterally arranged contiguous felt portions 40a through 400 which are adapted for the application of variable pressures against the corresponding web portions Pa Pc. As indicated again in FIGURE 4, the outer felts 40a, 40b overlap slightly the central felt 400 in order to make certain that there are no non-pressure areas in the middle portion of the web P and that a substantial pressure is applied across the full Width of the web P, even though perhaps less pressure may be applied to the web P along its edges Pa and Pb than along the central portion Pc thereof.

The embodiment of FIGURES 3 and 4 has the advantage of simplicity With respect to the use of only a single felt opposite any given portion of the paper web; but the embodiment of FIGURES 1 and 2 has advantages in the provision of more variables in controlling the drying rate, by way of the use of a plurality of felt layers over any given portion of the web. Also, the problem of effectively applying pressure to the interior portions of the web immediately adjacent the division lines between the separate and independent felt pressure applying means is simplified in the embodiment of FIGURES 1 It will be understood that modifications and variations.

may be eifected without departing from the spirit and scope of the novel concepts of the present invention.

I claim as my invention:

In a paper drying machine, a member having a rotatable cylindrical drying surface carrying a Web to be dried in a given direction; felt means covering the web and traveling with the Web and surface; separate, independent, longitudinally contiguous and laterally divided belt means moving with the felt means and web; and separate tensioning rolls engaging said respective and corresponding divided belt means for applying different tension forces therein and therefore correspondingly different normal pressures against the felt means and Web laterally thereacross, said tensions of the said belt means which are interiorly disposed being greater than the tensions in the belt means over the peripheral portions of the moving drying surface.

References Cited in the file of this patent UNITED STATES PATENTS 1,250,618 Morgan Dec. 18, 1917 1,689,743 Mullen Oct. 30, 1928 2,770,176 Novick Nov. 13, 1956 3,021,610 Winkler et al. Feb. 20, 1962 FOREIGN PATENTS 603,334 Germany Sept. 29, 1934 158,236 Austria Mar. 26, 1940 720,368 Germany May 4, 1942 905,488 France Dec. 5, 1945 462,816 Italy Apr. 5, 1951 954,126 Germany Dec. 13, 1956

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