US3291680A - Cylinder machine press assembly - Google Patents

Description

Dec. 13, 1966 E. J. JUSTUS ET AL CYLINDER MACHINE PRESS ASSEMBLY 6 Sheets-Sheet 1 Filed OOB. 17, 1965 INVENTORS JUS 77/3 A 'ITORNE 'S Dec. 13, 1966 J s-rus ETAL 3,291,580

CYLINDER MACHINE PRESS ASSEMBLY Filed Oct. 17, 1963 6 Sheets-Sheet 2 BY M a "a: NI:YS

A TTOA Dec. 13, 1966 E. J. JUSTUS ETAL 3,291,680

CYLINDER MACHINE PRESS ASSEMBLY Filed Oct. 17, 1963 6 SheetsSheet :5

/ A "IY )AWIJYS Dec. 13, 1966 E. J. JUSTUS ET AL 3,291,680

CYLINDER MACHINE PRESS ASSEMBLY Filed 001;. 17. 1963 6 Sheets-Sheet 4 EI A5 Dec. 13, 1966 E. J. JUSTUS ET AL 3,291,680

CYLINDER MACHINE PRESS ASSEMBLY Filed Oct. 17, 1963 6 Sheets-Sheet 5 .LO L 5/ 84 Dec.13, was E, Jug-m5 ETAL 329mm CYLINDER MACHINE PRESS ASSEMBLY Filed Oct. 17, 1963 6 Sheets-Sheet 6 PRIOR ART 4 .zs' I N VENTORS' ZLMW Q A T'IY )RNIEYS United States Patent 3,291,680 CYLINDER MACHINE PRESS ASSEMBLY Edgar J. Justus and Dennis C. Cronin, Beloit, Wis., assignors to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed Oct. 17, 1963, Ser. No. 317,022 4 Claims. (Cl. 162272) The instant invention relates to improvements in the art of paper making, and more particularly, to improvements in the art of paper making using the so-called cylinder machine.

In the cylinder paper making machine, the so-called cylinder is a large rotating drum with a foraminous forming surface which rotates in a vat or pond of stock, partially submerged in the stock, and with a reduced pressure in the interior of the cylinder, so that the stock will be caused to flow against the forming surface and deposit fibers thereon and water from the stock will press into the interior of the cylinder from the vat and be removed. The rotating cylinder on its uprunning side will thus carry a preliminarily formed paper web.

In general, there is provided a pickup felt which presents a lower run and an upper run. The cylinder machines, ordinarily provide a plurality of cylinders in vats mounted in succession, with the axes of the cylinders in generally parallel alignment, so that the'lower run of the pickup felt may pass over the top of each of the successive cylinders and usually be urged against the web thereon by a nip-defining roll, so as to pick up, in succession, the preliminarily formed paper webs from the top of each of the successively aligned cylinders, in this way a multi-ply paper web of substantial thickness may be formed.

Such multi-ply paper web is then carried on the socalled pickup felt along the underside of the-lower felt run until it passes the last of the cylinders, at which time the pickup felt is reversed in direction in what is considered to be an upper felt run with the preliminarily formed multi-ply paper web on the top surface thereof and the felt then returns along such top run back over the lower run moving in an opposite direction back to a starting point. The upper felt run will carry the web thereon through a series of dewatering press nips. Ordinarily, these dewatering press nips are defined by a top felt as well as the upper run of the pickup felt so as to sandwich the web therebetween to protect the same and in this manner the web is carried through successive press nips until it is dewatered to a significant extent. Then the top felt may be removed and the web is preferably passed through one or more additional press nips while still carried on the upper run of the pickup felt, for additional dewatering, and then the web is ordinarily separated from the upper felt run and passed through successive pressing andcompacting nips and on into the dryer section. The upper run of the pickup felt then proceeds to a reconditioning area from which it returns as the lower run of the pickup felt to again pass over the tops of the successive cylinders.

The general arrangement is old and well known in the art and cylinder machines are operated in some instances with only a single cylinder (or cylinder mol as it is sometimes referred to), but generally there is a plurality of successively aligned cylinders and the paper web that is formed is often a paper web of substantial thickness, sometimes called paper board, and this paper board is not ordinarily as diificult to handle as comparatively more delicate lighter weight paper webs, although certain difficulties in the handling thereof are recognized. One of these difficulties involves the very substantial amount of water that must be handled for the reason that each of the successive plies or layers of preliminarily formed paper web that are taken up by the lower run of the pickup felt passing over the cylinders contains a considerable amount of water and this results in a substantial total amount of water in a relatively thick web. Even though this web may be used and often is used in relatively inexpensive, lower quality paper board, often made from inexpensive waste materials, it is still important to produce the best possible quality and uniformity in such paper board or other relatively thick paper web material. The problems of crushing (which will be explained in detail hereinafter) and other problems recognized in the handling of other webs are also present in connection with the forma-' the upper run of the pickup felt are often suction press nips or similar devices customarily used for the handling of substantial quantities of water, but having the disadvantage of relatively great expense not only at the time of initial installation but also during operation. Suction rolls are expensive because of the cos-t of preparing the perforated suction roll shell as well as the initial costs of providing the necessary equipment for suction glands,

suction pumps, etc. In addition, there is a continuous operating expense for maintaining the suction glands in proper operating condition, and these expenses are recognized in the art.

The instant invention relates to certain fundamental improvements in cylinder machines employing selected press nips defined by press rolls having generally circum ferentially aligned alternating grooves and ridges on the surface thereof. It is appreciated that for a number of years prior art workers have suggested the use of grooved rolls for one purpose or another in paper making, but such grooved rolls were suggested and/ or used, if at all, for the most part quite early in the history of paper making and were discarded as being inadequate. In general, the suction roll has been found to be the press roll of choice for handling the substantial amounts of water involved; but in spite of the excellent jobwhich suction rolls may do in many instances, the cost thereof must be recognized as a significant factor. The instant invention provides certain grooved roll structures which have been found to be unique their ability to replace suction rolls in many if not all of the essential locations in cylinder mold machines.

It is therefore an important object of the instant invention to provide an improved cylinder or cylinder mold machine.

It is a further object of the instant invention to provide an improved cylinder machine having improved mechanical dewatering devices therein which comprise rolls having certain land and groove structures thereon.

Yet another object of the instant invention is to provide improved mechanical dewatering means for cylinder type machines which comprise grooved rolls of new and improved structure, used in new locations and/or arrangements or assemblies in cylinder mold machines.

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:

FIGURES 1A and 1B show two halves of an overall cylinder mold machine in an essentially diagrammatic side elevational view, and in referring to these two views, it will be seen that the full cylindermold assembly is shown by placing the right-hand edge of FIGURE 1A adjacent the left-hand edge of FIGURE 1B;

3 FIGURE 2 is another essentially diagrammatic side elevational view of a portion of a cylinder machine corresponding generally to the portion shown in FIGURE 13 hereof;

FIGURE 3 is an essentially diagrammatic side elevational view of a press mechanism which may be employed in the practice of the instant invention;

FIGURE 4 is a fragmentary detail view taken substantially along the line IV-IV of FIGURE 3;

FIGURE 5 is a plan view of a wire cleaner that is shown in operative arrangement in FIGURES 3 and 4;

FIGURES 6, 7 and 8 are essentially diagrammatic side elevational views of the other press assemblies which may be used in the practice of the instant invention;

FIGURE 9 is a fragmentary detail view taken substantially along the line A-A of FIGURE 1A;

FIGURE 10 is a fragmentary detail sectional view showing a portion of a suction press nip of the prior art;

FIGURE 11 is a view comparable to FIGURE 10 showing a portion of a press nip embodying blind drilled holes in one roll, as used in the prior art;

FIGURE 12 is a view comparable to FIGURES l0 and 11, but showing a fragmentary detail sectional elevation, with parts broken away, of a felt only nip embodying the instant invention (shown at N-14 in FIGURE 1A);

FIGURE 12A is a fragmentary detail sectional elevational view taken substantially along the line A-A of FIGURE 12;

FIGURE 13 is a sectional fragmentary elevational view comparable to that of FIGURE 12A (although slightly enlarged with respect thereto) taken generally along the line XIIIXIII of FIGURE 1B;

FIGURE 13A is a fragmentary enlargement taken from the encircled portion of FIGURE 13 designated VA;

FIGURE 14 is another fragmentary sectional elevational view comparable to the views of FIGURES 12A and 13, but taken substantially along the line designated XIVXIV in FIGURES 1A and 6 (and also taken substantially along the line XIVaXIVa of FIGURE 7);

FIGURE 15 is a fragmentary sectional elevational view comparable to that of FIGURES 12A, 13 and 14, but taken substantially along the line XVXV of FIGURE 1A; and

FIGURE 16 is still another view comparable to FIG- URES 12A, 13, 14 and 15, but taken substantially along the line XV IXVI of FIGURES 1A and/ or 8.

As shown on the drawings:

Referring to FIGURES 1A and 1B, it will be seen that the cylinder machine shown therein comprises a pickup felt 23 having a lower pickup felt run 23L shown in these two views as moving from right to left and an upper pickup felt run 23U shown in these two views as running from left to right above the lower pickup felt run 23L. The pickup felt itself is mounted on a plurality of generally conventionally arranged felt guide rolls 23a through 23m.

Referring to the travel of the pickup felt 23, it will be seen that starting at the lower right-hand corner of FIG- URE 1B, the pickup felt 23 returns from a conditioning area (not shown) where it is dewatered by a dewatering nip that is substantially identical to the nip N-14 shown in the left-hand side of FIGURE 1A. The felt 23 returns from this reconditioning area (not shown) and passes over a felt guide roll 23f and then past a series of guide and tensioning rolls 23g through k and into an initial pickup nip N between a top pickup roll and a rotating cylinder mold 51 in a vat V. This conventional vat structure V is shown essentially diagrammatically and is old and well known in the art and is per se not a part of the instant invention. In fact, the subsequent successive vats V-a through V-f shown in sequence from right to left in FIGURES 1B and 1A, respectively, are each conventional cylinder mold vats and the cylinder molds are shown in succession as 51a through 51f with pickup rolls 52a through 52 each defining successive pickup nips N-a through N]''. In these two views, also, the machine floor is indicated at F-1 and the conventional framing for the overall machine is indicated generally at F2.

The lower felt run 23L from the felt guide roll 23 to the felt guide roll 23a of FIGURE 1A, is thus essentially old and well known in cylinder machines of the prior art. Likewise, the return of the upper felt run 23U is generally old and well known in the fundamental arrangement here shown in FIGURES 1A and 1B. In other words, it is known to return the upper run 23U with the web W-l thereon and with such web W-l covered by an upper felt 11 through a plurality of press nips generally along the lines indicated in the press nip sequence N11, N-17, N-12, N-lS, N-16 and finally N-13, as here shown in FIGURES 1A and 1B. The essential novelty of the instant invention, however, resides in the use in certain locations in connection with the aforesaid press nips of grooved rolls of certain specific structural features, function and characteristics, which will be described in detail hereinafter.

Referring first to the guide roll 23a for the felt 23 in FIGURE 1A, it will be seen that the felt 23 passes upwardly around a suction roll '60 having an enlarged suction gland indicated diagrammatically at 60a to accommodate substantial water removal, and the web W-1 is then covered by the upper felt 11 and carried on the suction roll 60 into a first press nip N11 defined by the suction roll 60 and an upper grooved roll 61. It will be noted that the upper felt 11 is mounted in a generally conventional arrangement on a plurality of felt .guide and stretcher rolls 11a through lllj, and the upper felt 11 passes through a felt conditioning and dewaberiog nip N1'1 between the press rolls 15 and 16 at the oncoming side of the first web press nip N-11, as here shown.

The felt conditioning nip N-14 is indicated as being defined between a plain press roll 16 and a grooved press roll .15 in a press nip N44- which forms a part of the overall inventive concept 'here involved. As is indicated in FIGURES 9, 12 and 12A, the grooved roll 15 is provided with a plurality of very closely axially spaced alternating generally circumferential grooves 150, 15c and lands or ridges 15b, 15b out in a rubber cover 15a on the imperforate mild steel shell of the roll 15, indicated f-ragmenta rily at 15x only in FIGURE 12A. In general, the lands i15b have axial dimensions y-1 that are substantially equal to the axial dimension x-1 of the grooves at the outer periphery of the roll 15, but the grooves 150 are comparatively deep so as to have, in the view of FIGURE 12A, a cross-sectional area in each case that is at least as great as twice the square of the groove mouth width x-l, and preferably closer to about five times the square. In this arrangement, the grooves 15c have such substantial depth that they are substantially continuously vented to ambient atmosphere at both the oncoming and off-running sides of the nip N-14 so as to minimize resistance of fiow of water from the felt 11 into the grooves and peripherally away from the felt 11 in such grooves 150. If the machine is traveling fast enough, the rotating roll 15 will carry the water away in such grooves 150, but if the machine is traveling relatively slow, and many cylinder machines do travel relatively slowly, then the essential function of the [grooves 150 is to provide a continuous vent to ambient atmosphere from the nip N-14 so that water may flow continuously in such grooves 1'Sc away from the nip N-14 to dewater and condition the operating or outer peripheral surface of the felt 11 (probably by a flowof water to a substantial extent backwa'rdly or downwardly in the arrangement of the nip N-14) into a conventional saiveall arrangement designated generally by the reference letter m. If the roll 15 is rotating more rapidly, it is found desirable to avoid returning the water to the nip N-14 by wiping the lands 15c dry with a doctor indicated generally by the reference letter d and it is also found preferable to employ a pumping type of wiper w at the olfrunning side of the nip N-i14 to pump water from the grooves 150 into the saveall m. Hereinafter, saveall structures which are essentially sheet metal structures differing from each other only in their general contour (which contour will be shown in the diagrammatic views hereof) are herein-after designated by the reference letter m. Conventional doctors are designated by the reference letter d with their general location shown in each instance and the pumping type wipers which will be described in detail hereinafter are designated by the reference letter w in the views hereof. Essentially, the doctors a will be mounted in the savealls m so that they may function to wipe the peripheral surfaces of the various press rolls dry at the oncoming side of the various press nips in order to avoid ere-entry of water into the nip unnecessarily. Also, as indicated in connection with the nip N-14 it will be seen that felt guide rolls 11a and 11k are mounted so that the felt '11 is at least about tangential to the grooved roll 15 and is preferably mounted for the most part on the side of the plain roll "16 of a common tangent between the press rolls 15 and 16, so that there is a contact between the felt 111 and the grooved roll 15 at both the oncoming and offrunniug sides of the nip N-14. The lffilt -11 is thus completely reconditioned and dewatered to the extent desired in preparation for initial engagement with the web W-'1 at the immediate oncoming side of the first press ni-p N-ll. As indicated in FIGURE 15, the first press nip N41 is defined between a suction roll shell indicated generally at 60 having conventional relatively lange perforations 6% and 60c in the shell thereof with enlarged mouths of conventional structure, engaging the underside of the pickup felt 23. In FIGURE 15 the felts 111 and 13 are indicated in full view for convenience in study of this view and, in fact, in all of the fragmentary detail views comparable to FIGURE 15 hereof, the various felts will be shown in full view for such convenience. It will be seen from FIGURE 15 that the upper .roll 61, however, is provided with a substantial plurality of generally circumferential deep narrow grooves 610 between comparatively axially wider alternating generally circumferential lands 61b, formed on the rubber or other solid elastomer cover 61a for the grooved roll 61.

The function of the suction roll 60 is fundamental and well known and this general function is described in greater detail in connection with FIGURE 10 in a subsequent consideration of the relationship of the prior art to the instant invention. The function of the grooved roll 61, however, is distinctly different in this first press nip N-1i1 of a cylinder machine. Although the groove and land (61c and 61d) relationship is actually essentially that shown in FIGURE 13A hereof and discussed in substantial detail hereinafter, it is sutficient to note at this time that the grooves 610 are substantially smaller in axial dimension than the lands 61b.

In a relatively rapidly operating cylinder machine, such as that indicated in FIGURES 1A and 1B hereof, the roll 61 containing the relatively deep narrow grooves 610 moves sufliciently rapidly to not only receive water pressed into these grooves 610 from the web W-l through the felt 11, but also to carry away a substantial amount of such water in such grooves 610 as the roll 61 separates from the felt 11 and the surface thereof passes beyond the leading edge of the saveall m at the off-running side of the nip N-11. The grooves 610 are, of course, vented to ambient atmosphere by virture of the substantial depth thereof so that there is substantially no resistance to the receipt of water by such grooves 610 at the nip N-11 and these grooves 61c are sufliciently narrow to resist to a certain extent the return of water therefrom to the expanding highly absorbent felt 11 at the off-running side of the nip N-11. Instead, the water remains in the grooves to a substantial extent at the off-running side of the nip N-11 and is pumped therefrom by a pumping type wiper w which throws water droplets from the grooves into the saveall m. At the oncoming side of the nip N-11 a doctor wipes the lands 61b dry so as to minimize return of any water into the nip N-11. In this way an additional amount of water is actually removed from the web W-l at the first web nip N-11.

It will be appreciated that the nip load of water entering the nip N-ll is extremely high, but the nip pressure is relatively low so as to avoid damaging the web by crushing or otherwise at this first nip N-11.

The Web W-l sandwiched between the felts 23 and 11 then passes from the first nip N-11 to the second press nip N17 shown in FIGURE 1A, which is a nip defined between two grooved rolls 18 and 19 which are shown with only a slight modification in the larger view of FIGURE 8 and which define a nip N-17 that is shown essentially diagrammatically in the fragmentary detail view of FIGURE 16. As indicated in FIGURE 16, the upper roll 19 is provided with relatively narrow and deep grooves 190 between comparatively axially wider lands 1% in a rubber cover 19a. It will be appreciated that preferably at least one of each of the press rolls in any given press couple is provided with a solid elastomer, resilient-type surface so as to minimize damage by accident to the rolls, and in the embodiments of the invention most of the grooved press rolls are shown with solid elastomer covers in which the grooves may be readily cut. Such grooves may also be cut in more durable stainless steel covers or other types of materials in at least one of the press rolls forming any given press couple.

The lower press roll 18 at the nip N-17 (as indicated in FIGURE 16) is, likewise, provided with relatively narrow deep grooves 18c between comparatively wider land areas 18b in the ela-stomer cover 18a which engages the underside of the pickup felt 23 carrying the web W-l thereon. It will readily be appreciated that the deep grooves 18c are continuously vented to ambient atmosphere at both the oncoming and off-running sides of the nip N-17 so that they may function, first of all, to readily receive water pressed from the web W-1 through the felt 23, offering substantially no pressure resistance to such receipt of water. Secondly, these grooves are of sufficient size and depth to remain continuously vented to ambient atmosphere so that in a slowly operating cylinder machine or in the case of excessive water loads at the nip N-17 the water may actually flow away from the nip N-17 in such grooves 180, peripherally both forward and backward with respect to the nip N-17. The comparatively substantial dimensions of the lands 18b permit the application of the desired pressure along a nip load line which extends in a cross-machine direction at the center of the nip N17 or in a plane P-17 indicated in FIGURE 16. In the event that the cylinder machine is operating at a comparatively more rapid speed, as in the case of the machine shown in FIGURES 1A and 1B, it will be appreciated that the water expressed from the web W-l through the felt 23 does not merely flow in the grooves 18c away from the nip N17 but is actually carried away from the nip N17 at the oncoming side and is then removed from the grooves 180 by a pumping type wiper w mounted in an otherwise conventional saveall structure In and at the oncoming side of the nip N-17 the lands are wiped dry by a doctor a, as indicated in FIGURE 1A.

In the case of the upper grooved roll 19, it will be appreciated that the relatively narrow grooves may also carry water away from the nip N-17 in spite of the tendency of the upper felt 11 to reabsorb water at the immediate off-running side of the nip N-17, when such felt 11 will expand. The water carried away in the grooves 196 is preferably subjected at the immediate off-running side of the nip N-17 to a pumping type wiper which actually pumps the Water from the grooves 190 and throws the water into the saveall m. The grooved roll 19 is also provided with another wiper w at the downrunning side thereof which effects further removal of water from the grooves 190 and, also at the downrunuing side of the grooved roll 19 at the immediate oncoming side of the nip N17 a doctor is positioned to wipe the lands 19b clean and dry to minimize reentry of water into the nip N-17.

Referring briefly to FIGURE 8, it will be seen that certain changes in the top saveall m are useful in the function of the top grooved roll 19 in the event that the cylinder machine is operating at a relatively slow speed. If the cylinder machine is operating at a slow speed, the water in the grooves 19c will be readily received at the nip N-17 because of the nip pressure and because the grooves 190 are ventedto ambient atmosphere at both the oncoming and off-running sides of the nip N-17 in the previously described manner. However, if the machine is running too slowly it will be appreciated that as the roll 19 rotates upwardly the water may have a tendency to flow back in the grooves 190 and onto the highly absorbent, expanding felt 11 at the off-running side of the nip N-17. As will be explained hereinafter, the felt 11 actually creates a partial vacuum in the interior thereof as it expands at the off-running side of the nip N-11 and it is highly absorbent so that it could remove a substantial quantity if not all of the water forced into the grooves 190 at the off-running side of the nip N-11 if the machine is operating slowly enough. In such instances, however, we have provided a counteracting suction device indicated generally at 70 in FIGURE 8 at the off-running side of the nip N-17. It will be appreciated that the suction device 17 is a device having a pair of side walls having the general contour of the uprunning side of the roll 19 at the off-running side of the nip N-17 in the manner indicated generally diagrammatically in FIGURE 8 and there will be a top closure wall indicated at 70a extending axially the full cross-machine width of the roll 19 and a lower closure wall 7 b, likewise, extending axially the full width of the roll 19 so as to present a mouth 70c that is axially continuous for substantially the width of the grooved roll 19 at the immediate off-running side of the nip N-17 and this mouth is positioned in either touching or extremely close-running, sealing relation to the lands 19b of the grooved roll 19 so as to actually create a counteracting subatmospheric pressure in the grooves 190 and thereby draw water from these grooves 190 into the suction device 70. Appropriate evacuating pump means are indicated diagrammatically at 70d in operative association with the device 70. Air will sweep into the grooves in the direction indicated by the arrow marked A-17 just above the suction device 70 so as to sweep the water in the grooves 190 from the roll 19 and into the suction device 70. On the other hand, the reduced pressure provided by the mouth 70c of the suction device 70 will counteract the subatmospheric pressure that is ordinarily created in the expanding off-running felt 11 at the immediate off-running side of the nip N-1'7 so that reabsorption of water by the felt 11 may be minimized. It will be appreciated that in the comparatively more rapidly operating device described in connection with FIGURE 1A, the rotation of the roll 19 is sufficiently rapid to carry a substantial amount of water over to the first wiper w. In a slower device, or in the same device adapted for slower machine speeds, as indicated in FIGURE 8, the suction mouth 700 may provide the proper pressure balance for maintaining the water in the grooves 190 as the roll 19 rotates away from the nip N-17. At the downrunning side of the roll 19, the previously described pumping wiper w and doctor d carry out the functions already mentioned.

Referring now briefly to the part broken away in the lower grooved roll 18 of FIGURE 8, it will be appreciated first of all that the grooved roll 18 of FIGURE 8 has a structure substantially identical to that of the grooved roll 18 of FIGURE 1A.

An important aspect of the function and structure of the pumping type wipers as exemplified by the wiper w-18 of FIGURE 8 is worth considering here. It will be noted that the wiper w-IS (like all of the other pumping type wipers w herein indicated diagrammatically) is an axially continuous sheet, presenting an axially continuous surface portion along what amounts to a line of contact L-1 extending the full width of the grooved roll 18. Actually, this is a limited area of contact with the land's 18b and actual touching contact is obtained except in the case of water films on the lands 18b. For improved operation, it will be noted that a doctor d is also associated with the wiper w-18 for purposes of drying the lands 18b at the oncoming side of the wiper w-18 to improve the function thereof. In any event, the wiper w-18 is either in touching or very close-running relation to the lands 18b and separates slowly or gradually therefrom at the off-running side of the so-called line of contact L2 so as to create the pumping effect. This pumping effect is actually created by a partial vacuum resulting from the separation of the surface of the roll 18 and the metal sheet w-18 at the offrunning side of the line of contact L-1 and air A-18 rushes into the grooves and thereby drives the water therein (as indicated diagrammatically) out of the grooves 180, causing such water to follow the trailing edge of the wiper sheet w-18 and thus be thrown from the surface of the roll 18 into the saveall m. This pumping type wiper has a number of unusual advantages for the reason that is not required to penetrate into the grooves 180 and it may effectively dewater the same without penetration thereinto. In this respect, the doctors, d, d indicated at the two locations in association with the roll 18 in FIG- URE 8 are also preferably axially continuous devices for wiping water from the lands 18b of the roll 18. Air doctors may be used, if desired, but the simple mechanical doctor blade here shown is adequate and the doctor blade operates in such close-running relation to the surface of the roll 18 that it effectively touches the same (notwithstanding a theoretical residual water film of minimum thickness that would presumably pass even beneath a doctor which is pressed against the roll surface). The axially continuous doctor means d function primarily only to remove water from the lands 18b and such devices, likewise, do not penetrate the grooves 18c. This is important, as in the case of the pumping type wiper w-18 for the reason that it is often preferred to cut the grooves in a very slow orlow angle helix for convenience in the operation of machine tools used for this purpose. The generally helical grooves 18c will thus function to continuously clean both the wiper w-18 and the doctors d, which remain stationary while the roll 18 rotates. The helix angle is preferably very small, since generally circumferential alignment is desired at the nip N-17 for functional reasons (all as described in greater detail in the previously filed application of Edgar I. Justus, Serial No. 258,391, filed February 14,. 1963, now abandoned which is incorporated herein by reference.

Returning again to the travel of the web W-l between the felts 11 and 23 in FIGURE 1A, it will be seen that this sandwich structure next enters into the third press nip N-12 between a top plain roll 12 and a lower grooved roll 14. The grooved roll 14 has essentially the structure previously described in connection with the lower grooved roll 18. The nip N-12 is shown in fragmentary detail sectional view in FIGURE 14 and in View of the previous discussions in this case, itis believed that this view is selfexplanatory. Water removal at the third nip N-12 is effected essentially via the grooves 14c in the lower grooved roll 14 in the manner hereinbefore described. The essential difference between the nips N-12 and N-17 being that a greater nip pressure in pounds per lineal inch is preferably employed in the third press nip N-12 to effect the removal of additional quantities of water. In this respect, it will be appreciated that the double-header arrows centered on various rolls, such as the rolls 12 and 14 indicate diagrammatically anti-deflection roll mountings and conventional fluid actuated roll positioning and nip loading devices, all of which are described in greater detail in the previously mentioned application of Edgar Justus, Serial No. 258,391 and neen not be described in detail herein. It is sufiicient to note that the symbols suggested are used in the views hereof. The latter G is also centered on various rolls to indicate that such rolls are grooved rolls.

The fourth and fifth press nips N-15 and N16 shown in FIGURE 1 hereof are defined between successive press couples 12X14X and 12Y-14Y which are actually substantially identical in structure to the previously described press couple 12-14 at the nip N-12. The subsequent press nips N-15 and N-16, are, of course, preferably operated at successively greater nip loads in pounds per lineal inch in order to remove additional quantities of water more conveniently, but otherwise the structures are essentially the same.

In this respect, it will be appreciated that if certain cylinder machines of this general structure are operated with relatively great water loads at these later press nips N-12, N-lS and N-16, it is always possible to employ a suction roll in place of one of the previously identified grooved rolls. This would not be the preferred process ordinarily, but in certain instances where a suction roll has already been installed, it might be practical to retain the same at least until it is worn out and in so doing it will be appreciated that the nip load in such instance would be comparatively lower than could be achieved using the grooved rolls of the 14 series herein described, for the reason that the perforate shell of a suction roll does create certain limitations on the available nip load, although the perforate shell will afford additional ease of Water removal at very low nip loads in certain instances. Preferably, however, the rolls of the .14 series are all grooved rolls and they are employed in nips which are loaded, successively greater, for purposes of removing more and more water mechanically. ,At the off-running side of the nip N-16, the felt 11 on the top side of the web W1 separates therefrom passing around the guide roll 11 and returns to the felt conditioning nip N-14 in the manner shown in FIGURE 1A; whereas the felt 23 continues (as indicated in FIGURE 1B) on to still another web press nip N-13 defined between a plain upper roll 21 and a grooved lower roll 22. The grooved roll 22 has essentially the structure of the previously described grooved rolls of the 14 series, but it will be noted from FIGURES 13 and 13A that specific dimensions for the grooved roll 22 are shown in the fragmentary crosssectional views, and these views will be discussed in greater detail hereinafter in connection with the fundamental theory of the invention. It will be appreciated, however, that such discussion relating to the nip N13 and the relationship of the grooves 22c to the lands 22b of the roll 22 applies generally to the previously described grooved rolls 61, 18, 19, 14, 14X and MY, all as indicated in FIGURES 14, 15 and 16 hereof as well as FIGURES 13 and 13A. At the off-running side of the nip N-13 the felt 23 is carried away generally tangential to the grooved roll 22 over a guide roll 231 and the web W1 then separates from the felt 23 and passes on through a compacting nip N-20 defined by a pair of plain rolls 53, 54 of conventional structure. It will be seen that the saveall m, wiper w and doctor d arrangement associated with the roll 22 is substantially that already described in connection with the rolls ofthe 14 series and need not be described in greater detail herein.

As previously indicated, the felt 23 leaves the web press nip N13 passing around guide rolls 231' and 23d to be reconditioned in an arrangement essentially the same as that of the nip N-14, although it is not shown in the view of FIGURE 1B.

An improvement in this type of arrangement is shown in FIGURE 2 in that the web press nip N-13X defined by an upper plain roll 21X and a lower grooved roll 22X which function essentially in the manner hereinbefore described in connection with the nip N13 with respect to dewatering of the web W-2 on the pickup felt here indicated as 23X. The essential difference in the embodiment of FIGURE 2 is that the felt 23X turns around the guide roll 23d in FIGURE 2 and then returns over felt guide rolls 23r and 23s which align the felt 23X generally tangential with the nip N-24 that is provided as a felt only nip between the grooved roll 22X and a bottom grooved roll 24. It will be noted that the grooved rolls 22X and 24 are provided with the previously described doctors d at the oncoming side of the nip N13X and N-24 and also they are provided with wipers indicated diagrammatically at w in savealls m. In fragmentary cross section, it will be appreciated that the nip N24 will have the general structural view of FIGURE 16, except that only the felt 23 is pressed between the two grooved roll surfaces 1% and 18b of FIGURE 16, which would be designated in a corresponding view for the nip N-24 as 22b and 24b. Essentially, the lower roll 24 provides a grooved surface for acting against the outer peripheral surface of the felt 23X to dewater and clean and condition the same. The flow of water in the direction of the grooved roll 24 will assist in cleaning the outer surface of the felt 23X. Additional dewatering may be accomplished by the roll 22X in this three-roll divided press arrangement (i.e. 21X, 22X and 24), but at the machine speeds generally contemplated, it will be appreciated that a great deal of water taken out of the web W-2 through the felt 23X at the web press nip N-13X will travel or remain in the grooves of the roll 22X down to the nip N-24, where it will tend to move primarily through the felt 23X in the direction of the lower or bottom grooved roll 24 and thus further assist in washing and reconditioning the felt 23X. Any residual water retained by the roll 22X at the uprunning side thereof is.

however, removed by the auxiliary equipment indicatedv diagrammatically in the view of FIGURE 2.

Certain other embodiments of the instant invention are shown in the other views. For example, in FIGURE 6, it will be seen that the preivously described third press nip N-12 is shown :being defined between the preivously described upper plain roll 12 and the lower grooved roll 14. The fragmentary cross section of the nip is, of course, shown in FIGURE 14 hereof. The difference in FIGURE 6 relates to the manner in which water is removed from the grooves 14c of the rubber cover 14a on the ductile iron imperforate shell 14x of the roll 14 indicated in FIGURE 14 hereof. The saveall m-14 for the bottom grooved roll 14 in the nip N-12 of FIGURE 6 is, however, different in structure and function. First of all, it will be appreciated that an axially continuous mouth 71c is presented in a suction device 71 comparing in structure and function to that previously described under the reference numeral 70 in FIGURE 8, with an axially continuous oncoming wall 71b and an axially continuous offrunning wall 76a and appropriate sealing side walls such as the one indicated diagrammatically in the side elevational view of FIGURE 6, conforming with the contour of the roll 14 and urged thereagainst to the extent of effecting a sealing arrangement whereby the vacuum header 71d may produce a very low pressure within the hood 71 (e.g. 2 to 5 pounds per square inch, absolute) and this will cause air to rush into the grooves at A-6 beneath the wall 71b at the oncoming side of the hood 71 and also at A6x at the grooves 14c beneath the off-running wall 70a, so that a suction effect is obtained for removing water from the grooves 14c. The device 71 would be used preferably in the case of slowly operating machines wherein the previously described wiper w cannot generate satisfactory pumping effect because of the slow speed and/ or when the previously described wiper w is overloaded and because of the substantial quantity of water cannot carry out the complete function desired.

In this respect, it should also be noted that the saveall m-14 mounts a metal sheet 5-14 at the oncoming side of the nip N-12 in order to separate the bottom felt 23 from a pool of water which might otherwise tend to collect at the oncoming side of the nip N-12. Again, the sheet device 8-14 is axially continuous and it extends to the immediate edge of the oncoming side of the nip N-12 so as to guide the flow of water from the nip N12 through the grooves 14c without permitting any buildup of water in what would be a visible puddle of water on top of the lands 14b at the oncoming side of the nip N-12. Such a puddle of water would, of course, add water to the felt 23 coming into the nip N-12 and would thus reduce the overall effectiveness of the function of the nip N-12. It will be appreciated that the rolls 12 and 14 may thus define a dewatering nip N-12 for relatively higher speeds and smaller water loads, as indicated in FIGURE 1A, or for slower speeds and/ or very high Water loads, as indicated in FIGURE 6, in which instance the water expressed from the web W-1 through the felt 23 not only flows away from the nip N-12 in the grooves 14c but actually tends to fill the same, even to overflowing at the oncoming side (although such overflowing is substantially precluded by the sheet S44). It will also be appreciated that the leading edge of the saveall m-14 at E-14 at the off-running side of the nip N-12 may also be extended into very close proximity to the off-running side of the nip N-12 so as to make sure that the water in the grooves 140 will have a minimum opportunity to rewet the felt 23 as it expands at the off-running side of the nip N-12. The tendency for the building up of a puddle of water is, however, characteristic usually at the oncoming side of the given nip N-12 rather than the off-running side, so the sheet S-14 does have a peculiar function in this respect.

Referring now to FIGURE 7, it will be seen that FIG- URE 7 shows an upper plain press roll 12' and a lower grooved press roll 14 having structures substantially identical to those of the previously described rolls 12 and 14, but these two rolls 12 and 14' are now used to define a first press nip N-ll', which may :beused to replace the structure at the first press nip N-11 of FIGURE 1A.

First of all, in FIGURE 7, it will be appreciated that the upper press roll 12 could very easily be replaced by the exact structure of the roll 19 with saveall m and suction hood 70 shown in FIGURE 8 and an additional dewatering function would thus be carried out in the position of the roll 12' here shown in FIGURE 7. Secondly, the bottom roll 14 is shown in FIGURE 7 as a substitute for the suction roll 69 at the first press nip N-11 in FIGURE 1A. In order to use the grooved roll 14 in this position, it must be appreciated first of all that an additional felt guide roll 23t for the pickup felt 23' is required in order to align the felt 23' substantially tangentially with the two rolls 12' and 14' at the nip N-ll'. The guide roll 11k for the upper felt 11' is also aligned correspondingly, and the web here indicated as W-7 is thus moved into position between the two felts 11' and 23' substantially ahead of the nip N-ll. The fragmentary sectional view of the nip N-ll taken substantially along the line XIVa-XIVa will, of course, be substantially the same as the view shown in FIGURE 14 hereof, except that the primed reference numerals are not used in FIG- URE 14 hereof.

Essentially the problem at the first nip N-ll is that the water load is so great that additional devices beyond those preivously indicated in FIGURE 1A for use with the roll 14 are required in associated with the roll 14'. It will be appreciated that the devices just described in connection with FIGURE 6, which include the sheet 5-14 and the vacuum header 71 can be used for certain rather high water loads in associated with the roll 14 at the first press nip N-ll', as shown in FIGURE 7, although the structure shown in FIGURE 7 is capable of handling exces- I2 sive waterloads in a somewhat superior manner because of its versatility.

As indicated in FIGURE 7, a conventional wiper w and conventional doctors d, (1 may be used to assist in water removal from the roll 14' in an otherwise conventional saveall m-7. Inaddition thereto, a hood element indicated generally at 72 is provided at the oncoming side of the nip N11' below the felt 23 and in operative (sealing) association with the surface of the roll 14 in accordance with the general principles already described for the hoods 70 and 71 shown herein. The hood 72 thus presents an exposed mouth 72c to the grooves between oncoming 72b and off-running 72a sealing walls, and the hood 72 is here shown diagrammatically connected to a vacuum header V via an open valve 81. In this arrangement the valve 81 is open to the vacuum header V Where as the valve 82 here shown diagrammatically connected to a pressure header P is closed. A symmetrical counterpart to the hood 72 is indicated at the off-running side of the nip N11 by the reference numeral 73 and this hood 73 at the off-running side is also capable of connection to the vacuum header V via a valve in line 83 or to a pressure header P via a valve in line 84. It will be appreciated that either of the hoods 72 or 73 may be employed connected to the vacuum header V in the manner described so as to assist in effecting a reduced pressure for withdrawal of water from the grooves 14c and avoidance of any buildup of a water puddle or pool at either side of the nip N41. It will also be appreciated that either of the vacuum hoods 72 or 73 may be used alone for this purpose. In addition, the hood 73 may be connected to an air pressure header P to the valve 84 so as to drive water back away from beneath the felt 23' in the grooves 14c at the nip N41 and into the hood 72 which would then be operated preferably in connection with the vacuum header V. Again, the pressures in the two hoods 72 and 73 may be reversed so as to drive water in the direction of the hood 73 which would then be connected via the valve 83 to the vacuum header V. It Will be appreciated that either of the hoods 72 or 73 may actually be operated in the total absence of the other, but preferably in combination with some sort of a guard, e.g. comparable to the sheet S14 of FIGURE 6, to control water movement, and in such instances either of such hoods 72 or 73 might be operated under vacuum or under pressure. Essentially, the function of the device of 72 and 73 is to accelerate removal of the water in the grooves Me at the pressure line or load line of the nip N-11, so that a greater total load of water may be handled at this nip N-ll. In practice, grooves in the neighborhood of about ,-5. inch in the roll 14' may be used, with lands of approximately %2 inch in axial dimension, in order to remove-very great water loads and the auxiliary equipment such as the hoods 72, 73, the guard sheet S44, and the like are used when even greater water loads must be handled and it is not desired to increase the groove size beyond the dimensions already described. It will be appreciated that the groove size in a felt protected grooved roll in the first or second press nips N11 and N17 may not be quite as critical as, for example, in the case of the last Web press N13 of FIGURE l B, because the groove size may be relatively large in the early press nips and may be so large as to cause some tendency toward web marking, whereas the rather numerous subsequent press nips shown herein can effectively erase whatever tendency toward marking might have been created by larger grooves at the earlier press nips. Preferably, however, the grooves used in the practice of the instant invention take advantage of the fact that structures are available for the use of sulficiently narrow grooves to prevent any significant marking of the web, and the various auxiliary structures herein described in connection with FIGURES 6, 7 and 8 among others are thus used to take care of thewater load, rather than enlarging the grooves. It will also be appreciated that enlargement of the grooves not only may cause shadow marking of the web but it will also cause excessive wear of the felt because the felt will be driven into the grooves.

and then have to be pulled back out again at the offrunning side of the hips and this procedure will accelerate felt wear and it will also tend to wear away the preferred relatively sharp edges at the groove mouths, having the structures indicated in the various detail views of FIG- URES 12 through 16 hereof.

FIGURE 3 shows one remedy for minimizing felt wear in such instances when the groove width is very substantial compared to the groove widths hereinbefore described.

In the groove widths hereinbefore described, in the detail views of FIGURES 12 through 16, it will be appreciated that in FIGURE 12A, for example, groove widths of x1 in the neighborhood of 9 inch or even as much as 0.035 inch may be used particularly in the case of a bottom grooved roll at a first or second web press and certainly in the case of a bottom grooved roll in a felt only press nip, as here shown. In FIGURE 12A the lands y-l are shown as being of equal width. In FIGURES 13 through 16, however, the lands are of an axial dimension y that is generally 3 to as much as 20 times the axial groove dimension x. Preferably, the maximum groove dimension x is in the neighborhood of about inch, although still better results are obtained by reducing the groove width x to 0.25 and 0.20 inch. The lands in contrast, are preferably about 0.80 to 0.1 inch (although they may actually range conveniently from 0.50 to 0.15 inch). Essentially, the relationship between the lands y and the grooves x is such that the open area (which would be x divided by the sum of x plus y) is not significantly more than about 25% and is preferably within the range of about 15 to 20%. These reduced open areas give a distinctly superior function in minimizing rewetting of the highly absorptive expanding felt at the off-running side of the nip.

FIGURES 4, 5 and 6 hereof show a somewhat different concept of the invention, for the reason already explained that the grooves 91c (FIGURE 4) have rather substantial axial dimensions x-4 of perhaps "as much as 0.5 to 0.6 inch. Preferably the lands 91b have approximately at least about two or three times such groove width, in a dimension indicated at y-4, so that the total open area will be maintained in the desired lower range. It will be seen, however, that the wires 92, 92 (which will be described in greater detail) shown in FIGURE 4 in the grooves 910, will add to the effective total land area so that the desired open area of about 25% or even 10 to is still obtained.

Referring to the overall structure shown in FIGURE 3, it will be seen that the press couple of FIGURE 3 indicated generally by the reference numeral 90 comprises a top plain press roll 92 and a bottom grooved roll 91 for use in a felt only nip N-90 receiving a given felt indicated at 95. The felt only nip N-90 could be used in place of the previously described felt only nip N-14 in FIGURE 1A. The groove 91c and land 91b structures are shown in FIGURE 4. It will be appreciated, however, that in the embodiment of FIGURES 3, 4 and 5 the grooves 910 and the lands 91b are truly circumferential and not slightly helical (with even a very small helical angle). This is because wires 92, 92 are actually extending in generally parallel alignment between supports 94a and 94b at the oncoming and oifruning sides, respectively, of the nip N-90 and with such rolls 92 extending a generally parallel alignment, any significant helical angle in the grooves 91c would necessarily cause undesirable relative crossmachine movement between the wires 92 and the grooves 910. As indicated in FIGURE 5, the device indicated generally by the reference numeral 94 that is employed involves merely a pair of side frames 94a and 94b of suitable structural material such as metal to which are connected a plurality of parallel fine wires 92, 92, 92 etc. in closely spaced parallel relationship (the device 94 being shown only fragmentarily in the prospective of FIGURE 5), so that there is one wire 92 for each groove 910 in the full cross-machine dimension of the grooved roll 91.

These wires 92 serve to provide resilient support for the felt 95 going through the nip N-90. At the oncoming side of the nip N- the wires 92 resiliently urge the felt up so that it does not enter into the grooves 910 at the oncoming side. At the maximum pressure zone or load line of the nip N-90, it is possible that the felt 95 will actually be compressed or pressed to such an extent that it will enter into the relatively wide mouths of the grooves 91c by virtue of the pressure of the top roll 94, pressed against the bottom roll 91. In fact, in the view of FIG- URE 3, it will be seen that the view is exaggerated for its showing of the felt 95 having pushed the resilient wires 92 down into the grooves 910 at the nip N-90, but it will be appreciated that even though this is accomplished, the grooves 910 are deep enough so as to remain continuously vented to ambient atmosphere at both the oncoming and otf-running sides of the nip N90 and water is thus continuously driven against what amounts to the resistance of ambient atmospheric pressure; and at the immediate offrunning side of the nip N-90 the resilient wires 92 will immediately urge the felt 95 back out of the grooves 910 and away from the water in the grooves, so that this separation of the felt 95 from the interior of the grooves 910 coupled with physical presence of the wires 92 to reduce the overall effective open area has a tendency to minimize greatly the ability of the expanding felt 95 to reabsorb water from the grooves 910 and effective water removal is obtained in the desired manner. It will be appreciated that the press nip N-90 could be used with a web, except that any condition which would involve forcing of the felt into the grooves 91c would almost surely cause marking of the web, so the nip N-90 is preferred for use in a felt only press and may be used to great advantage in effecting substantial water removal as well as conditioning and cleaning of the felt 95. An additional wire cleaner indicated at 94' at the underside of the grooved roll 91 may be used to considerable advantage in arrangements involving essentially truly circumferential grooves 910 such as are here described. In the embodiment of 94", the wires 92' are resiliently urged into the very bottom of the grooves 910 at the underside of the roll 91 and these wires function to clean and purge the grooves, removing fibers, clay, dirt, etc., and also actually driving water back out of the grooves 910 not only at the oncoming side of the device 94' but also at the off-running side, because there will be some pumping action as the grooves 910 separate from the Wires 92' at the off-running side of the device 94'. Additional pumping type wipers and/ or doctors may also be used in the practice of the invention in connection with the roll 91 and, of course, a saveall m-91 of appropriate structure is provided.

One of the problems in web pressing is avoidance of crushing of the web which is perhaps a poorly chosen but very meaningful word of the artactually meaning incipient fracture of the web-caused by excessive, poor ly directed water flow in the web at the nip. Thus, referring to FIGURE 12, it will be seen that at the oncoming side of the nip N-14, the pressure P in the porous belt or felt 23 is nominal (i.e. about-15 pounds per square inch, absolute); whereas at the middle or cross-machine center line of the nip N-14 the pressure P is at a maximum (usually at least as great as the nip load in pounds per lineal inch or greater because the longitudinal dimension of the maximum nip load is often less than 1 inch); and, of course, at the off-running side of the nip N-14 the expanding felt 11 tends to create a subatmospheric (or vacuum) pressure P (e.g. 2 to 5 pounds per square inch, absolute) depending to a great extent upon the ability of the porous felt or belt 11 to receive ambient atmosphere. If the web W-1 were also present in this nip, it will be appreciated that the pressed web W1 is substantially nonporous in this condition andthe ability of the felt to receive ambient atmosphere on the web side would thus be materially reduced.

Referring now to FIGURE 13, it will be seen that the web W-l is shown with the felt 23, but the section of FIGURE 13 and 13A is taken in the cross-machine direction, thus generally aligned with the maximum pressure P The maximum pressure P w'hen crushing takes place is so much greater than the oncoming or ambient pressure P that in the case of a substantial total water load entering the nip N-13 of FIGURE 13 there is created a flow of water in the Web from P toward P in the plane P--P of the web W-l. Generally the paper machine operator will see evidence of this in the form of a puddle at the oncoming side of the nip and in this instance the water flow is in a direction constituting from left to right in FIGURE 12, but it is in the actual plane of the web W-l, which is not shown in FIGURE 12. The Web W-l is shown in FIGURES 13 and 13A and it must be appreciated that there is still another type of crushing flow which may take place. In this instance the crushing flow is in the cross-machine direction, which would thus be from the machine direction center line M of the land area 22b to the mouth of the groove 226 immediately adjacent thereto. Expressing the land width in terms of y, the dimension with which we are concerned is thus one-half y as indicated in FIGURE 13A. This dimension is so small in the embodiment of the instant invention that the chance of an adequate pressure differential between P and P (which would be the pressure at the mouth of the vented groove 220) being sufficient to cause crushing flow in the web W-l is substantially eliminated. It is thus important that the land width y be maintained at a relatively low maximum of perhaps 0.15 inch. The minimum is about 0.05 inch for practical purposes and preferably y is about 0.08 to 0.1 inch. It should further be appreciated, however, that the previously recognized evidence of crushing in the form of a pool or puddle at the oncoming side of a nip will not necessarily be evidence of crushing in the embodiment of the instant invention. This is because the water may flow very readily from the maximum pressure regions along the line M to the vented grooves 220 and then backwardly out of the nip via the grooves 22c to form what would appear to be a puddle at the underside of the felt, particularly with big Water loads. As mentioned in connection with FIGURE 6 hereof, this puddle of water is separated from the oncoming felt 23 by the guard or sheet S14.

As previously mentioned, it is particularly important that the grooves be of sufficient size and depth to vent fully and readily. In fact, during many cylinder machine operations in particular the speed of the machine is so slow that the venting must be suflicient to accommodate quite a substantial flow of Water in the grooves and such venting is not merely an amount sufficient to permit the ready receipt of water in the grooves under the pressure at the nip. Referring to FIGURE 13A, it will be noted that the groove width has been expressed generally by the term x and it will be appreciated that the groove depth y2 in FIGURE 13A is about /8 inch whereas the groove width is about 0.20 inch or 0.25 inch, so that the cross-sectional area of each groove 22c in the view of FIGURE 13A is approximately times the square of the axial dimension as of the groove mouth. Preferably, the groove depth y is a minimum of at least 0.50 and the cross-sectional area, which of course is a function of the volume, should thus be a minimum of at least about 2 times the square of x and preferably 4 or 5 times such square.

It will thus be seen that shallow and/ or sharply tapered grooves, having somewhat circular or triangular crosssectional area which is functionally significantly below that of twice the square of the groove mouth width are either incapable of satisfactory venting or incapable of satisfactory resistance of return of water to the highly absorbent felt at the off-running side of the nip, or both.

Throughout the specification and claims the term felt is used in its generic sense to mean not only more conventional woolen felts but also so-called felts of different weights, weaves and openness, including reinforced felts, porous fabrics and similar porous belts which may be composite, integral or separable porous elements.

The range of axial dimensions (in the absence of wires such as the wires 92) is a practical range of about 0.005 to about 0.035 inch, with land axial dimensions of about 0.050 to 0.15 inch. Using the wires 92 and/or using extremely great water loads in the first or second press nips in the device of FIGURES 1A and 1B hereof, it will be appreciated that larger grooves, even up to as much as perhaps fis inch, may be used particularly with the wires 92 in felt only nips, but it is difficult or impossible to avoid marking of webs with such large groove sizes and correspondingly larger land dimensions y may cause crushing or other undesirable results.

It will be appreciated that groove structures of the general type described in considerable detail in the aforesaid application Serial No. 258,391 and many of the theoretical considerations mentioned therein apply in the instant use and such disclosure is incorporated herein by reference. Essentially, however, the concept of the instant invention involves the use of such grooved rolls in the cylinder machine in the locations and for the purposes hereinbefore specified. The rolls 61 and 19 herein shown have groove widths of 0.020 inch with land widths of 0.1 inch for approximately 16% open areas, whereas the lower grooved rolls 18, 14, 14X, 14Y and 22 and 22X, shown herein are formed with groove widths of 0.020 and lands of 0.080 inch for a 20% open area. In the case of the embodiment of FIGURE 7, the roll 14 has groove widths of inch and lands of inch because of the high water load and in instances involving the use of an upper roll that is grooved at the first press nip N-Il' of FIGURE 7, the structure of the rolls 61 or 19 is used.

In cutting any of the grooves hereinbefore described, it will be appreciated that a slight machine taper is permitted, but generally speaking the walls are preferably substantially radially aligned, as indicated in FIGURE 12A at 15c-1 and 15c-2 or in FIGURE 13A at 22c-1 and 22c2. The dimension of principal concern is, however, the dimension x at the mouth and the walls 220-1 and 22c-2 may have various configurations including a spacing greater than the mouth opening x, so long as the volume requirements previously expressed in terms of the crosssectional area are met.

It will be appreciated that the principle involved in water removal in the practice of the instant invention is entirely different from that heretofore used in the art. For example, in FIGURE 10, in the suction press nip N-4, the roll shell 31 is perforate, being provided with a multiplicity of holes 32, 32 of substantial size (i.e. at least about 4 inch in diameter and usually having flared peripheral mouths 32a of greater size) which are drilled entirely through the roll shell 31 (having at least about 1 inch thickness) to communicate with the suction gland G extending the full width of the roll shell 31 exteriorly opposite the nip N-4. At the suction press nip N4, a press felt 33 is interposed between the web W 10 and the perforate suction roll shell 31 (primarily as a water-permeable protective layer for the web W-10), and water expressed from the web W10 passes completely through the felt 33 and into these holes 32, 32 in the perforate shell 31. Some Water continues into the gland G and some is usually retained in these holes 32, 32 at the off-running side of the nip N-4, where the sub-atmospheric pressure in the gland G tends to counteract centrifugal forces urging water droplets back out of the holes 32, 32 and against the felt 33 under ambient atmospheric pressure. The felt 33 may thus remain in contact with the web W-10 at such off-running side of the nip N4 without substantial re-wetting of the web W-10. In spite of the excellence of the performance of perforate suction rolls for a number at uses in paper making, it must be conceded that these rolls and their auxiliary equipment are expensive to n1anufact lre.v The suction roll indicated at 60 in FIGURE 1A demonstrates that suction rolls may be used in conjunction with grooved rolls in the practice of the instant invention and that they have real utility therein, particularly highly loaded nips, but the operation is expensive and the instant grooved rolls when substituted for the suction rolls will effect a reduction in any tendency toward shadow marking of the web.

Recently the so-called divided press type of structure which does not employ a suction roll has been proposed. The purpose of this is to use press rolls at the so-called web nip which are less expensive to operate and which do not cause any marking of the web. For example, in FIGURE 11 hereof, it will be seen that a nip N for the web is provided with press rolls 35, 35a in which one of the press rolls covered by a felt 37 is provided with minute recesses on the surface thereof to temporarily take the load of Water entering the nip N-S to prevent crushing of the web W3 carried by the felt 37. As indicated in FIGURE 11, a preferred form of such recess 36 is provided by a rubber cover on a press roll 35 that contains a myriad of comparatively fine blind drilled holes (ie of approximately to inch or even less diameter, as in the case of Walker US. Patent No. 3,023,805); and such fine holes 36, 36 will in the case of most conventional Webs W-3 and felts 37 substantially avoid or eliminate the shadow marking characteristic of the performance of certain perforate suction rolls. In this divided press arrangement, however, the water removal principle is substantially different, Water is not carried away from the nip N-5 by a suction roll shell or by grooves or by any other means. Instead, water is merely temporarily stored in the blind drilled holes 36, 36 at the nip and then immediately returned to the felt 37 at the off-running side thereof. This does involve additional complications of separating the Web and felt and otherwise managing the flow of water which are not involved in the practice of the instant invention.

It will be appreciated that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of the present invention.

We claim as our invention:

1. A pair of rolls defining a nip receiving a moist porous felt material for dewatering the same, at least one of said rolls being a grooved roll formed of an imperferate press roll shell presenting to the felt touching the same a peripheral surface portion having a plurality of alternating generally circumferentially aligned grooves and ridges, said ridges presenting to such felt smooth generally cylindrical closely axially spaced land areas for supporting the felt and permitting the felt to bridge the grooves and thereby protect against substantial marking in the case of any web carried on the felt into the nip defined by such grooved roH, said grooves being vented to ambient atmosphere at the oncoming and off-running sides of the nip defined by such grooved roll to facilitate reception of water from the felt at the nip, and means maintaining a wire in each of the grooves of such grooved roll at the nip to limit penetration of felt portions into such grooves at the nip.

2. A pair of rolls defining a nip receiving a moist porous felt material for dewatering the same, at least one of said rolls being a grooved roll formed of an irnperforate press roll shell presenting to the felt touching the same a peripheral surface portion having a plurality of alternating generally ciroumferentially aligned grooves and ridges, said ridges presenting to such felt smooth generally cylindrical closely axially spaced land areas for supporting the felt and permitting the felt to bridge the grooves and thereby protect against substantial marking in the case of any web carried on the felt into the nip defined by such grooved roll, said grooves being vented to ambient atmosphere at the oncoming and off-running sides of the nip defined by such grooved roll to facilitate reception of water from the felt at the nip, and means maintaining a multiplicity of resilient elongated generally parallel elements urged separately intoeach of said grooves in the grooved roll at the nip for limiting the penetration of the felt into the grooves at the nip.

3. A pair of rolls defining a nip receiving a moist porous felt material for dewatering the same at, least one of said rolls being a grooved roll formed of an imperforatc press roll shell presenting to the felt touching the same a peripheral surface portion having a plurality of alternating general-1y circumferentially aligned grooves and ridges, said ridges presenting to such felt smooth generally cylindrical closely axially s aced land areas for supporting the felt and permitting the felt to bridge the grooves and thereby protect against substantial marking in the case of any web carried on the felt into the nip defined by such grooved roll, said grooves being vented to ambient atmosphere at the oncoming and off-running sides of the nip defined by such grooved roll to facilitate reception of water from the felt at the nip, and means maintaining a multiplicity of resilient elongated generally parallel elements urged separately into each of said grooves in the grooved roll remote from the nip for cleaning and dewatering each such groove.

4. In a cylinder machine for paper making, in combination, a plurality of cylinder molds aligned in vats, a looped pickup felt having a lower r-un passing over the tops of said cylinders to pick up successive layers of webs therefrom and an upper run returning with such web layers thereon, a top looped felt engaging the web layers on such upper run, a plurality of successive press rolls within the top felt loopeach defining a web press nip with a press roll within the pick-up felt loop beneath the upper run for dewatering the web between such felts, at least one of said press rolls being a grooved roll formed of an imperforate press roll shell presenting to the felt touching the same a peripheral surface portion having a plurality of alternating generally circumferentially aligned grooves and ridges, said ridges presenting to such felt smooth generally cylindrical closely axially spaced land areas for supporting the felt and permitting the felt to bridge the g-rooves and thereby protect against substantial marking in the case of any Web carried on the felt into the nip defined by such grooved roll, said grooves being vented to ambient atmosphere at the oncoming and off-running sides of the nip defined by such grooved roll to facilitate reception of water from the felt at the nip; and means maintaining a multiplicity of resilient elongated generally parallel elements urged separately into each of said grooves in the groove roll at the nip for limiting the penetration of the felt into the grooves of the nip.

References Cited by the Examiner UNITED STATES PATENTS 1,483,562 2/1924 Wagner 162-358 1,503,426 7/1924 Robinson 162-123 1,717,878 6/1929 Ellis 162-133 1,718,096 6/1929 Wells 162-133 2,019,845 11/1935 Colbert et al. 162-304 2,083,818 6/1937 Berry 162-358 2,083,819 6/1937 Berry 162-358 2,656,768 10/1953 Breyfogle 162-304 2,858,747 11/1958 Wagner 162-361 3,138,518 6/1964 Greenhouse et al. 162-133 3,198,697 8/1965 Justus 162-360 DONALL H, SYLVESTER, Primary Examiner. J. H. NEWSOME, Assistant Examiner.

Claims (1)

1. A PAIR OF ROLLS DEFINING A NIP RECEIVING A MOIST POROUS FELT MATERIAL FOR DEWATERING THE SAME, AT LEAST ONE OF SAID ROLLS BEING A GROOVED ROLL FORMED OF AN IMPERFORATE PRESS ROLL SHELL PRESENTING TO THE FELT TOUCHING THE SAME A PERPHERAL SURFACE PORTION HAVING A PLURALITY OF ATERNATING GENERALLY CIRCUMFERENTIALLY ALIGNED GROOVES AND RIDGES, SAID RIDGES PRESENTING TO SUCH FELT SMOOTH GENERALLY CYLINDRICAL CLOSELY AXIALLY SPACED LAND AREAS FOR SUPPORTING THE FELT AND PERMITTING THE FELT TO BRIDGE THE GROOVES AND THEREBY PROTECT AGAINST SUBSTANTIAL MARKING IN THE CASE OF ANY WEB CARRIED ON THE FELT INTO THE NIP DEFINED BY SUCH GROOVES ROLL, SAID GROOVES BEING VENTED TO AMBIENT ATMOSPHERE AT THE ONCOMING AND OFF-RUNNING SIDES OF THE NIP DEFINED BY SUCH GROOVED ROLL TO FACILITATE RECEPTION OF WATER FROM THE FELT AT THE NIP, AND MEANS MAINTAINING A WIRE IN EACH OF THE GROOVES OF SUCH GROOVED ROLL AT THE NIP TO LIMIT PENETRATION OF FELT PORTIONS INTO SUCH GROOVES AT THE NIP.

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