US3470063A - Papermaking machine - Google Patents

Description

Sept. 30, 1969 c. L. SANFORD PAPERMAKING MACHINE 2 SheetsSheet 1 Filed Jan. 27, 1965 nv mam Sept. 30, 1969 c. L. SANFORD 3,470,063

PAPERMAKING MACHINE Filed Jan. 27, 1965 2 Sheets-Sheet United States Patent 3,470,063 PAPERMAKING MACHINE Charles L. Sanford, Memphis, Tenn., assignor to Kimberly-Clark Corporation, Neenah, Wis., a corporation of Delaware Filed Jan. 27, 1965, Ser. No. 428,516 Int. Cl. D21f 1/10, 11/06 US. Cl. 162--303 2 Claims ABSTRACT OF THE DISCLOSURE My invention relates to papermaking machines and more particularly to such machines of the type in which substantial dewatering of the stock in forming of the web is accomplished by applying tension on the forming fabric or wire carrying the paper web to be dewatered as the forming fabric passes about a curved surface.

It has previously been prosposed in the application of Charles A. Lee et al., Ser. No. 161,058, filed Dec. 21, 1961 (now Patent No. 3,224,928, issued Dec. 21, 1965); and in an application of John B. Graham, Ser. No. 419,765 filed Dec. 21, 1964, now Patent No. 3,400,045, that a paper web may be formed by directing a paper stock slurry between a so-called breast roll and a socalled slice roll which carry a forming wire, the wire extending around both rolls including a substantial arc of the slice roll and bridging a gap provided between the two rolls, and the stock being directed on to the portion of the wire bridging these two rolls. A top felt passes around the slice roll so that the paper web being formed lies between the wire and felt on this roll, and the web is dewatered primarily due to the force of the wire bearing on the roll and beairng on the web and felt between the wire and roll, the force of the wire being due to the tension applied on to the wire. Although some of the water from the web is thrown from the wire as it passes around the slice roll due to centrifugal force, some of it remains and collects within the interstices of the wire and on the outer surface of the wire.

It is an object of the present invention to provide mechanism for removing at least some of the water remaining in the interstices of the forming wire and on the outer surface of the wire so that dewatering of the web is more complete as it passes around the slice roll.

In brief, this object may be accomplished according to the teaching of the invention by providing a porous surfaced roll having contact with the outer surface of the forming wire on the part of the wire supported by the slice roll, with the porous surfaced roll acting to collect and remove a portion of the water clinging to the forming wire. Alternately, in lieu of the porous surfaced roll, a porous belt may be put into contact with the surface of the forming wire; and, if desired, the belt may be made to wrap a portion of the slice roll so as to apply additional pressure on to the web formed around the slice roll and provide additional dewatering action on the web.

The invention consists of the novel constructions, arrangements and devices to be hereinafter described and claimed for carrying out the above stated objects, and such other objects as will be apparent from the follow- Patented Sept. 30., 1969 ing description of preferred forms of the invention, illustrated with reference to the accompanying drawings, wherein:

P16. 1 is a diagrammatic elevational view of a papermaking machine having a wet end section embodying the principles of the invention; and

FIGS. 2 and 3 are diagrammatic elevational views of modified wet end sections which may be used in lieu of the wet end section of the machine illustrated in FIG. 1.

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

Referring to FIG. 1 of the drawings, the papermaking machine therein illustrated may be seen to comprise a loop of web forming fabric or wire 20 which is disposed about rolls 21, 22, 23, 24, 25, 26, 27, 28 and 29. The fabric 20 is a conventional paper web forming fabric or wire for use in Fourdrinier machines made up of interwoven warp and shute filaments for providing drainage openings therebetween through which water may drain from dilute paper stock applied on the fabric. The strands may be either metal or synthetic material in accordance with well-known practice. The roll 21, which is relatively large in diameter in comparison with the other rolls, may be termed a slice roll; and the roll 29, which has its center located appproximately above the center of the roll 21 and which is somewhat smaller in diameter than the roll 21, may be termed a breast roll. The roll 22 is a couch roll and has both ends fixed; and the rolls 23, 24, 27 and 28 are simple turning rolls having both ends fixed. The roll 25 may be used as a stretch roll with conventional mechanism (not shown for simultaneously adjustably moving both ends of the roll and maintaining the fabric 20 taut about the rolls. The roll 26 is a conventional guide roll having one end fixed and the other end movable; and any suitable conventional apparatus (not shown) may be connected with the movable end of the roll 26 so that the roll 26 functions to maintain the fabric loop 20 traveling in substantially the same path about the rolls supporting the fabric. One or more of the fabric supporting rolls, such as the slice roll 21 or the couch roll 22, may be driven for the purpose of driving the fabric 20, so that the fabric travels over the fabric supporting rolls, all of which turn.

It will be observed that the fabric 20 passes around the roll 29 and bridges the rolls 21 and 29, which have a slight gap between them, and then passes around the roll 21, covering an arc of about of the roll 21. The fabric 20 then passes in a direct path to the couch roll 22, around the roll 22, beneath the roll 23, over the roll 24, beneath the roll 25, over the roll 26, and over the upper peripheral surfaces of the rolls 27 and 28. Any suitable doctors and water showers may be used in connection with the fabric 20 and with the rolls supporting the fabric, such as the doctors 30, 31 and 32, and the showers 33, 34 and 35. All of the rolls supporting the fabric 20, including the rolls 21 and 29, may be of solid construction as distinguished from hollow perforated construction, although the roll 22 is preferably provided with narrow circumferential water receiving grooves in its peripheral suface.

An upper loop of fabric 36 is disposed about rolls 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 and 51, in addition to the rolls 22 and 21. The fabric 36 is preferably one that absorbs water to a greater extent and releases water more easily than does the usual Fourdrinier wire and may be a conventional top felt used by paper makers. The fabric 36 is in direct contact with the exterior surface of the slice roll 21, and the fabric 20 lies on top of or outside of the fabric 36 as the fabric 36 passes over the roll 21. The rolls 46, 48 and 51 are preferably suction rolls as illustrated, and the other roll may be solid.

The roll 42 is a conventional stretch roll having both ends simultaneously adjustably movable by suitable adjusting mechanism (not shown) for maintaining the loop of fabric 36 taut about the rolls supporting the loop. The roll 40 is a conventional guide roll having one end fixed and the other end movable under the control of any suitable control mechanism (not shown) for maintaining the fabric 36 traveling in a predetermined path about the rolls supporting the fabric. The rolls 46 and 48 are pressure rolls, and each of these has a pressure nip with a steam heated Yankee drier 52 of conventional construction. Creping doctors 53 and 54 are provided for creping paper web from the surface of the Yankee drier 52, the doctors 53 and 54 being alternately so operable. The roll 51 constitutes one roll of a main press 55 which also includes a roll 56 having a pressure nip with the roll 51. A roll 57 is preferably provided in connection with the roll 22 for holding the fabrics 20 and 36 firmly in contact on the surface of the couch roll 22. The other rolls 37, 38, 39, 41, 43, 44, 45, 47, 49 and 50 supporting the fabric 36 are simple turning rolls. Any of the rolls supporting the felt 36, such as the roll 21, may be driven for moving the felt about its supporting rolls.

The wire 20 and the felt 36 travel as a sandwich, that is, the wire 20 and fabric 36 are in contact in their path of travel about the roll 21 and from thence to the roll 22. A third fabric loop 58 passes between rolls 51 and 56. The fabric 58 is preferably a bottom felt conventionally used in papermaking. The fabric 58 passes around rolls 59, 60, 61, 62, 63, 64, 65 and 66, in addition to the roll 51. The roll 66 constitutes one roll of a wringer 67 which includes also another roll 68 held to have a pressure nip with the roll 66. The roll 64 is a conventional guide roll having one end fixed and the other end movable under the control of a suitable control mechanism (not shown) for maintaining the fabric 58 traveling in a predetermined path about the rolls supporting the fabric. The roll 61 is a conventional stretch roll having both ends simultaneously adjustably movable by suitable adjustable mechanism (not shown) for maintaining the loop 58 taut about the rolls supporting the loop. The other rolls 59, 60, 62, 63 and 65 are simple turning rolls.

A stock inlet 69 is provided for directing paper stock between the rolls 29 and 21 and particularly on to the portion of the fabric 20 that bridges the narrow gap between the rolls 21 and 29. The inlet comprises a pair of plates 70 and 71 which have facing parallel flat surfaces defining an elongated slot between them. The plates 70 and 71 are horizontal, so that stock discharges between them through the slot defined by the plates horizontally into the nip between the rolls 21 and 29.

The fabric 20 and felt 36 leave the surface of the roll 21 along a line 72 on the surface of the roll 21 that is parallel with the axis of the roll 21. A roll 73 is in contact with the fabric 20 as it passes around the slice roll 21 along a line 74 which is slightly spaced from or immediately ahead of the line 72 on the surface of the roll 21.

The roll 73 may be made to simply have a non-forceful contact with the wire 20 or may be made to bear on the roll 21 and thereby on the wire 20 with a substan tial force such as, for example, up to 50 pounds per lineal inch, so that the roll 73 acting in conjunction with the roll 21 functions somewhat as a press, squeezing water from the paper web passing between the rolls 73 and 21. The roll 73 is provided with a porous surface. The roll 73, for example, may be hollow and may be provided with an array of holes drilled through its peripheral surface; alternately, the roll 73 may be solid and may be provided with circumferential grooves or with an indented thread in its surface. As another alternative, the roll 73 may be solid and may be provided with a jacket about its peripheral surface made of a wire similar to the wire 20 with interwoven warp and shute filaments providing interstices between them. If grooved or threaded, the grooves or thread may, for example, be .025 inch wide with .100 inch lands between the grooves or turns of the thread, and the grooves or thread may have a A inch depth, for example.

A water shower 77 and a pair of suction boxes 78 and 79 in contact with the fabric 36 are preferably provided above roll 45 for cleaning the fabric, for removing fines from the fabric so that it is not plugged by the fines, and for dewatering the fabric whereby it is presented to the roll 21 in a clean, relatively dewatered condition.

In operation, paper stock slurry is supplied to the inlet 69, and the paper stock passes through the slot between the parallel plates 70 and 71 and discharges horizontally into the gap between the rolls 21 and 29 and on to the portion of the fabric 20 bridging the gap between these rolls. The plates 70 and 71 may, for example, be 8 inches to 30 inches long and may be spaced less than an inch apart, such as inch to inch, so as to impart a fine scale turbulence to the stock passing between them, in accordance with the teachings in the copending application of David W. Appel et al., Ser. No. 278,521, filed May 2, 1963, now abandoned. The paper stock starts to drain immediately on contact with the wire 20; and the stock passes, as it forms into a web, around the roll 21, being disposed between the felt 36 and wire 20. The web in passing around the roll 21 in a sandwich between the wire 20 and felt 36 is dewatered primarily due to the force with which the wire bears on the roll 21 and on the intermediate web and felt 36 because of the tension maintained on the wire around the roll, although centrifugal force also helps in dewatering. The Water from the web being formed between the wire 20 and felt 36 about the surface of the roll 21 passes outwardly into the interstices of the wire 20 and tends to cling to the outer surface of the wire. Centrifugal force in particular is effective tending to outwardly throw the water in the interstices of the wire 20 or clinging to the wire or at least keeping the water draining from the stock within the interstices of the wire 20 as it passes about the roll 21, rather than permitting the water to be reabsorbed into the felt and paper web. The water will re-enter the web and the felt 36, if permitted, particularly at or beyond the place of separation of the wire and felt along the line 72 at which centrifugal force is no longer effective.

Assuming that the roll 73 is made to forcefully bear on the roll 21, the roll 73 squeezes water from the paper 'Web passing between the rolls 73 and 21 and densifies the web. The roll 73, due to its porosity, also functions, whether it has a forceful or non-forceful nip with the roll 21, to remove all or a part of the free water exising within the interstices of the wire 20 or clinging to the wire 20 prior to the line 72 at which the wire 20 and felt 36 leave the slice roll 21 and beyond which the feltweb-wire sandwich is not subject to centrifugal force due to traveling around the center of the roll 21. The free water within the interstices of the wire 20 or otherwise carried by the wire enters into the threaded grooves or drillings of the porous surfaced roll 73, or into the interstices of the wire jacket provided on the roll 73, and the roll 73 attracts this water and removes is from the wire; and the water is subsequently thrown outwardly from the surface of the roll 73 due to centrifugal force as the roll 73 rotates. If desired, in order to assist in removing the water from the roll 73, an air doctor 75 or a wipe 76, or both air doctor and wipe similarly effective, may be provided on the roll 73. The air doctor 75 may simply constitute a plurality of jets or an elongated slot directing air under pressure on the surface of the roll 73, and the wipe 76 may simply constitute a slab of flexible material riding on the surface of the roll 73.

The web continues along with the wire 20 and felt 36 to the rolls 22 and 57, and the wire 20 separates from the felt 36 at this point, the paper web continuing with the felt 36 and traveling on the underside of the felt. The web follows the felt 36 rather than the wire 20 at this place, since the felt is considerably more dense than the wire.

The felt and Web travel through the main press 55, and the press 55 is effective to press some of the remaining water from the web traveling on the underside of the felt, and this dewatering action is augmented by the bottom felt 58 which functions to absorb water from the web as the web passes through the press. The felt 36, continuing to carry the web on its under surface, passes around the rolls 50 and 49 t0 the pressure roll 48, and the web transfers from he felt 36 on to the drier drum 52 in the nip between the roll 48 and the drum 52. As the drum 52 rotates, the web is carried on the outer surface of the drum through the nip between the pressure roll 46 and the drum; and the pressure roll 46 also has a dewatering action on the web and causes sure adherence of the web on the drum 52. The Web in traveling with the drum 52 to the doctor blades 53 and 54 is dried, and one or the other of the blades 53 and 54 doctors the web from the drum 52. The web is then reeled into rolls by any suitable reeling equipment (not shown).

The porous roll 73 advantageously removes free water clinging to the outer surface of the wire 20, or water within the interstices of the wire 20, so that the water cannot reenter the paper web between the wire 20 and the felt 36, particularly as the wire 20 and felt 36 leave the slice roll 21 along the line 72 located adjacent to the roll 73. Therefore, there is less water that must be removed from the paper web by the main press 55, by the rolls 46 and 48 pressing the web between them and the drier durm 52, or by the drum 52 itself due to its drying action. The web also is drier at the line of pickup, at which the wire 20 separates from the paper web and felt between the rolls 22 and 57, thus reducing danger of disturbances to the wet web at this point.

The wet end section of the papermaking machine illustrated in FIG. 2 may be used with the same press section and drying section illustrated in FIG. 1, and differs principally from the FIG. 1 embodiment in that a loop 80 of coarsely woven wire or fabric is substituted for the porous roll surface of the roll 73. The fabric '80 is supported by means of rolls 73x, 81, 82 and 83. The roll 73x is placed in the same relation to the roll 21 as the roll 73 in the first described embodiment; and the other parts of the machine are similar to those in the first embodiment and are given the same reference numerals but with the subscript a added.

The roll 73x may be a solid roll and holds the fabric 80 in contact with the external surface of the forming wire 20a preferably with a substantial force. The roll 81 may be a simple turning roll; the roll 82 may be a guide roll suitably controlled in movement at one end of the roll; and the roll 83 may be a stretch roll movable at both ends to maintain the fabric 80 taut. The fabric 80 may consist of interwoven filaments of either metal or synthetic organic material and essentially may be similar to the forming wires 20 and 20a. The fabric 80 may, for example, be of 40 mesh, that is having 40 filaments to the inch both transversely and longitudinally. The fabric 80 collects water from the external surface or from the interstices of the wire 20 into the interstices of the fabric 80 and the fabric 80 thus has much the same dewatering action with respect to the forming wire 20a and the web between the felt 36a and wire 20a as the roll 73 provided with a wire jacket on its peripheral surface has with respect to the fabric 20 and the Web disposed between the fabric 20 and the felt 36 in the first embodiment. The water collected by the fabric 80 is thrown from it as the fabric passes about the rolls 81, 82 and 83.

The modified wet end section illustrated in FIG. 3 is similar to that illustrated in FIG. 2, except that a longer fabric y, corresponding to the fabric 80, is used; and the fabric 80y is made to wrap a portion of the periphery of the slice roll 21b instead of simply having a narrow nip with the roll 21b. The parts of the machine illustrated in FIG. 3 are similar to the correspondingly numbered parts in the first and second described embodiments, with the parts in the FIG. 3 embodiment being provided with reference numerals to which the subscript b has been added.

The fabric loop 80y extends around rolls 81b, 82b, 83b and an additional roll 84, as well as around a portion of the periphery of the slice roll 21b. The rolls 81b and 84 are disposed on opposite sides of the slice roll 21b so that the fabric 80y extends around nearly 90 of the slice roll 21b as this embodiment of the invention is illustrated. The fabric 80y first contacts the surface of the fabric 20b along the line 85 extending parallel with the axis of the roll 21b and leaves the fabric 20b along a similar line 86 which is quote adjacent to but spaced from the line 72b at which the wire 20b and felt 36b leave the roll 21b. The fabric 80y may be of the same type as the fabric 80 in the FIG. 2 embodiment.

In operation, the fabric 80 removes excess water from the surface of the forming wire 20b similarly to the action of the fabric 80 in the FIG. 2 embodiment, due to the contact that the fabric 80y has with the external surface of the forming wire 20b about the slice roll 21b, prior to the line 72b at which the fabric 20b and felt 36b leave the surface of the slice roll 21b. The fabric 80y, moreover, has an additional function of applying additional dewatering pressure on the paper web being formed around the periphery of the roll 21b for a substantial are on the surface of the slice roll 21b, this additional pressure being due to the substantial tension applied on to the fabric 80y and, therefore, the force with which the fabric 80y bears on the roll 21b. This pressure by the fabric 80y on the sandwich formed by the wire 20b, the felt 36b and the intermediate web being dewatered, results in additional dewatering of the web with the least possible disturbance of the web within the wire-Web-felt sandwich.

The fabric 80y thus provides a second sustained stage of pressure application for a substantial are about the slice roll 21b to the paper web being formed between the wire 20b and felt 36b..The first stage of pressure application on the web, during which the pressure is relatively low, is due to the force with which the fabric 20b itself bears on the first portion of the wire-web-felt sandwich just following the portion of the wire 20b bridging the rolls 29b and 21b. This pressure is due to the tension in the forming wire 20b itself. The fabric 80y, due to the tension maintained on the fabric, also applies a force on the wire-web-felt sandwich on the arc of the roll 21b contacted by the fabric 80y, and this force in this are is added to the force due only to the tension in the forming wire 20b. Thus, a certain pressure is applied by the forming wire 20b in the first part of the forming area for the web between the breast roll 29b and the line 85 at which the fabric 80y first contacts the wire 20b, and a higher pressure is applied in the second part of the forming area between the line 85 and the line 86 at which the fabric 80y separates from the periphery of the roll 21b.

Each of the embodiments of the invention, assuming that the rolls 73 and 73x have pressure nips respectively with the rolls 21 and 21a, have additional water removal capacity as compared to the first two embodiments of the invention in cases in which the rolls 73 and 73x have no such pressure nips. These embodiments, including the first two having such pressure nips, may be particularly useful for forming heavier webs, and the fabrics 20. 20a and 20b may be used with less tension than would otherwise be required. Also, with the second stage of pressure application, the slice and breast rolls may be spaced farther apart. Therefore, using the second stage of pressure application on the slice rolls, either with the rolls 73 and 73x forcefully applied on to the slice rolls, or using the fabric 80y which forcefully bears on a substantial arc of the slice roll 21b, more stock, and stock of greater consistency, may be discharged into the gap between the breast and slice rolls without any rejection of the stock back toward the inlets 69, 69a and 69b. The required overall pressure for a substantial dewatering of the paper web being formed is, in these cases, principally supplied in the second part of the forming area. Also, using the embodiments to apply web dewatering pressure in a second stage, webs of a given weight may be formed at higher speeds due to the additional water removal capacity provided in the second stage.

Thus, it is apparent that the fabric 80y, as well as the rolls 73 and 73x, not only may have the function in attracting free water carried by the forming wire of the particular embodiment; but the rolls 73 and 73x, by having pressure nips with the associated slice rolls 21 and 21a, and the fabric 80y, in forcefully bearing on the slice roll 21b due to the tension maintained on the fabric 80y, have the additional function of applying additional pressure on to the paper web being dewatered in a second part of the forming area about the slice rolls which is spaced not only from the lines at which the forming fabric and felt first contact the slice roll, but also from the lines at which the fabric and felt leave the slice roll.

What is claimed is:

1. In a paper web forming machine, the combination of an endless paper web forming fabric having interstices therethrough for draining paper stock deposited thereon, an endless felt, means for supporting and moving said fabric and felt each in the form of a loop and including a plurality of rolls, said rolls including a slice roll and both said fabric and felt passing around it for a substantial arc with said forming fabric being outermost and including a second roll disposed in proximity to said slice roll having said forming fabric passing around it and bridging to said slice roll and also including a third roll having said forming fabric passing from a line of amgency with said slice roll to the third roll, a paper stock inlet arranged to direct paper stock between said slice and second rolls so that the stock drains through said forming fabric to form a web between said fabric and N do felt which passes around said slice roll, and a fourth roll presenting a porous surface in contact with a portion of said forming fabric which is supported by said slice roll prior to said line of tangency as the forming fabric travels about said slice roll for removing water clinging to the forming fabric as it passes around said slice roll.

2. In a paper web machine, the combination of an endless paper web forming fabric having interstices therethrough for draining paper stock deposited thereon, an endless felt, means for supporting and moving said fabric and felt each in the form of a loop and including a plurality of rolls, said rolls including a slice roll and both said fabric and felt passing around it for a substantial arc with said forming fabric being outermost and including a second roll disposed in proximity to said slice roll having said forming fabric passing around it and bridging to said slice roll and also including a third roll having said forming fabric passing from a line of tangency with said slice roll to the third roll, a paper stock inlet arranged to direct paper stock between said slice and second rolls so that the stock drains through said forming fabric to form a web between said fabric and felt which passes around said slice roll, a third endless fabric having interstices therethrough, and a plurality of rolls for movably supporting said third fabric so that a portion of it lies in contact with the outer surface of said forming fabric on the surface of said slice roll prior to said line of tangency as the forming fabric travels around said slice roll, whereby said third fabric collects water clinging to said forming fabric and removes it from the forming fabric.

References Cited UNITED STATES PATENTS 2,694,345 11/1954 Hornbostel 162--352 X 3,224,928 12/1965 Lee et al. 162-303 X S. LEON BASHORE, Primary Examiner A. C. HODGSON, Assistant Examiner US. Cl. X.R. 162--214, 352

Images