US2881678A - Method and apparatus for making paper or paper board or similar fibrous product - Google Patents

Description

P 14, 1959' R. J. THOMAS 2,881,678

METHOD AND APPARATUS FOR MAKING PAPER OR PAPER BOARD OR SIMILAR FIBROUS PRODUCT Filed June 10, 1957 2 Sheets-Sheet 1 'A CARRIER BAND H FORMING AREA B UPPER PERMEABLE SURFACE J Sucs FoR UPwARo 0 PLAIN (LE. mPERFoRATs) ROLLER REMOVAL OF.WATER D Pom) OF TURBULENT PULP K PULP BOX E WEDGE-SHAPED GAP F Sucnon Inoucso BY ROTATING ROLLER G GIVENOF CARRIER BAno A BENEATH RoLLER"C"(sHowN ExAeeERATEo) 27 H/igs.

April 14, 1959 R. J. THOMAS 2,881,678 METHOD AND APPARATUS FOR MAKING PAPER OR PAPER BOARD OR SIMILAR FIBROUS PRODUCT Filed June 10, 1957 2 Sheets-Sheet 2 fHi/Erz [Ur PEG/M41 0 (194453 7 700145 United States Patent METHOD AND APPARATUS FOR MAKING PAPER OR PAPER BOARD 0R SIMILAR FIBROUS PRODUCT Reginald James Thomas, Weston-Super-Mare, England, assignor to St. Annes Board Mill Company Limited, Bristol, England, a corporation of England Application June 10, 1957, Serial No. 664,814 Claims priority, application Great Britain June 12, 1956 4 Claims. (CI. 92-44) This invention relates to the making of paper or paper board or similar fibrous products.

In the co-pending United States application filed by myself and Stanley Fred Smith, Serial No. 373,382, filed August 10, 1953, now Patent No. 2,821,120 granted January 28, 1958, there is described and claimed a meth- 0d and apparatus for making paper or paper board or similar fibrous products from a layer of watery pulp delivered to a traveling carrier band, or the already formed pulp carried by said band, which includes a permeable member covering the pulp and moving with the hand to provide another pulp forming surface receiving water from the pulp therethrough. This water is removed from the permeable member so as not to rewet the pulp. The band and permeable member are urged toward each other to squeeze the pulp therebetween for assisting in the removal of water from the pulp.

The squeezing of the watery pulp by the above referred to apparatus brings about a restriction in free flow of the watery pulp or formed pulp on the carrier band. This restriction results in the building up of a turbulent pool or pond of pulp extending rearwardly or upstream from the position where the squeezing action commences. The length of the turbulent pond or pool upstream from the pressure point will depend on the speed of movement of the carrier band.

The covering or top permeable band member is trained around a directing roll raised above the carrier band so the layer of stock enters a gap between the two bands and an air-stock interface is provided at least in the entrance mouth of the gap. The two bands then converge to the restriction or pressure point which is preferably created by a waterway in the form of a slice or doctor pressed against the top hand some distance from the directing roll. The gap between the two bands or wires thus converges from its entrance mouth to the waterway and has a wedge shape.

The present invention is concerned particularly with the utilization of an imperforate directing roller or memher around which the covering or upper permeable band or wire is trained. This imperforate roller member is lowered toward the bottom band or wire and a wedgeshaped gap is thus provided between the wires as the top wire travels downwardly around the lower portion of the imperforate roller. If desired, the entire wedgeshaped gap can be confined to this area underneath the directing roller and the slice or doctor can be positioned close to the directing roll to form the pressure point or terminus for the wedge-shaped gap. In other words, the whole of the upper part of the wedge-shaped or tapering gap can be constituted by that portion of the periphery of the imperforate roller and that portion of the upper forming wire thereon which is moving under the lower part of the roller at any given moment.

The wedge-shaped gap-defining imperforate roller has a suction pump eifect on the stock in the gap and tends to pull water through the upper permeable member as the periphery of the roller leaves the top Wire.

1 2,881,678 Patented Apr. 14, 1959 According to this invention the carrier band or bottom wire has an unsupported span under the directing roller so that the wire can be deflected under the influence of pressure in the gap. The deflection somewhat follows the curvature of the roller.

It is then an object of this invention to provide a paper or board making machine of the type disclosed in the Thomas and Smith US. Patent No. 2,821,120, filed August 10, 1953, wherein the directing roll for the top or covering forming wire is imperforate and'is moved down close to the main carrier band to define a wedgeshaped forming gap substantially confined under the roller.

Another object of this invention is to provide a paper or board making machine wherein a layer of watery pulp on a main carrier band is covered with a top forming wire trained around an imperforate directing roller pressing the top wire against the main wire and definin a wedge-shaped forming area between the wires underneath the roller.

A still further object of this invention is to provide a paper or board making machine of the type wherein watery pulp is formed on a covering wire wherein the covering wire is trained around an imperforate roller creating a tapered web-forming gap and effective to pump water from the pulp through the top wire as the top wire leaves the roller.

A'still further objectof this invention is to provide an apparatus of the type disclosed in the Thomas and Smith Patent No. 2,821,120, wherein the doctor or slice is moved close to the oncoming directing roller to confine the web-forming gap under the roller.

A still further object of the invention is to provide a paper machine having a top forming wire coacting with a bottom forming or carrier wire around an imperforate directing roller defining a tapered wedge-shaped throat relationship between the wires and efiective to sweep water from a layer of Watery pulp in the throat through the top wire.

Other and further objects and advantages of this inven tion will be apparent to those skilled in this art from the following detailed description of the attached sheets of drawings which are made a part of this invention.

On the drawings:

Figure l is a fragmentary, diagrammatic view of converging forming wires or hands in a paper or board making machine according to this invention; and

Figure 2 is a diagrammatic, side elevational view of a paper or board making machine embodying the present invention.

As shown on the drawings:

As shown in Figure 2, the paper or board making machine 10 includes a lower traveling permeable carrying band or main forming wire A trained around a plurality of rolls 11 to 17, inclusive. The wire A has a horizontal top run with an unsupported span or reach between the rolls 11 and 12. This main forming wire A may extend only around the terminal roll 15 for a single unit machine or it may extend beyond the roll to provide a machine having a plurality of additional dewatering units including the additional unit shown in broken lines. The parts in brokenlines corresponding to the parts in heavy lines shown in this view, are designated by primed reference numerals or letters.

A covering or upper traveling permeable band or forming wire B coacts with the main forming wire A and, as shown, is trained around a plurality of rolls 18 through 23 and around the imperforate directing roll C positioned above the unsupported reach of the top run of the bottom forming wire A intermediate the rolls 11 and 12.

A stock inlet K discharges an open topped layer of stock or waterypulp 'on 'theupper run of the forming 'V/IIC A preferably "in advance'of the wedge gap formed between the wires by the/directing roll C although the discharge from the inlet K can be directly fed into this gap.

A waterway in the form of a 'slice or doctor I with a water receiving trough is mounted in the loop of the top forming'wire'B closely .adjacentthe "directing roll C to press againstthe topwire; The'top wire has an open run or draw or unsupported span between the roll C and the doctor or slice I.

The rolls 12 and 18, 13 and 19, and 14 and 20, are arranged in pairs toprovide presses which squeeze the wires A and B toward each otherto "dewater a webbetween the wires downstream from 'thewaterway 1. Suetion slice 24 and 25 are'mounted in the loop of the top wire B adjacent the press rolls 18. and 19 to remove water from the top' wire.

The web formed between 'thewires is'uncovered as 'the top wire B'moves around the :roll 20 and this'web "can then be removed from the mainwire A. into the conventional press and dryer sections of a Fourdrinier'p-aper making machine or can remain on "the wire A and receive another open topped layer of stock'thereon from the inlet K which layer is then covered by the second top forming wire B and is formed thereon on top 'ofthe previously formed web.

In accordance with this. invention and as best. shown in Figure 1, the directing roll C is imperforate and is moved down close to anunsupported span of the top run-of the main forming wire A. As shownin Figure l, the upper forming wire B 'is wrapped around the underpart of the roll C and defines'with the main wire Aa'converging or wedge-shaped gap'E, The opentopped layer of stock or watery;'pulp "deposited on the wire Aby the inlet K forms a pond of turbulentwatery pulp D appreaching the gap E and as'this turbulent pond 'or pool is trapped in the gap by the converging path of the top forming Wire B, a force is'built up in the pool which causes the main wire Ato deflector give .as'shown at G. This deflection occurs directly beneath 'the imperforate roll C. The pressure built'up in thepool by the force of the imperforate roll C urged by the deflected carrier band A in the region G, accelerates dewatering of the stock in this pool. :The deflection of the wire A diminishes so that .the wire assumes itsnormal course shortly after the directing roll C leaves the top wire B and the gap E thus has a narrow end immediately downstream from the point'where'the wire B leaves the roll C as shown at H. A forming area is thus provided at H where water can be forcedupwardly from the pool through the top forming wire B. The doctor or slice I then urges the top wire B against the bottom wire A to define a pressure point or terminal end of the gap and this forming area H lll'lllSIllCS between the roll C and the slice 3. In this area'water is expressed upwardly through the 'top wire Band due to the momentum built up by the advancing wire, the water will flow over the slice 1 into the trough at the upper end of the slice.

The rotating imperforate roller C, as it ascends away from the top wire B, creates 'a suction which has .an effective pumping action to pull water through the top wire and assist in formation of the web in the top wire.

In operation an opened topped layer of watery pulp is fed to the main traveling carrier band A from a stock inlet and is carried therebyinto thev tapering gap E.

The pressure of theimperforate roller Cleanses the buildup of a pool D or pond of pulpextending from the roller C. in an upstream direction for a distance depending on the speed of travel of the "carrier bandA. The height of the pond D also depends on .this speed.

Formation of the web cannot take place, however, on the portion of the upper band B in'contact with the roller C because it is obturated thereby, thougha very slight amount of formation may take-place due to water being hand A. extent to obturate the carrier band A and'so at thepo- 4 forced into the mesh of the upper band C. It is to be understood, however, that water may pass downwardly through the traveling carrier band A and to some extent downward formation of a fibrous web results.

The majority of the watery pulp from the pond D is carried along beneath the roller C and as it passes beyond said roller C, water is forcedupwardly through the upper permeable forming wire B, passes up the slice J and is removed. Thereby formation of the web is effected partly on the upper forming wire B also.

When employing in accordance with this invention an imperforate roller C to obturate the upward flow of water and thus causing give G of the main carrier band A beneath the roller .0, the forming area H extends beyond .the tapering gap E formed between the imperforate roller 'C'andthe carrier band A when at rest, that is, when the machine :ismnning the forming area H extends beneath the roller C, above the yielding carrier band A, as far downstream as the slice -J or other pressing member arranged beyond-the rollerC. It might be expected that'blockingof the forward flow of the watery pulp may occur in the region G where the carrier band gives and that as a consequence uneven web formation would take place, but in practice this isnot the case. The reason for this appears to .be as follows. When a roller C i 'rotating, particularly at high speed, in contact with ;or in closeproximity to .a-travelling permeable band B,

such as the Fourdrinier carrier wire of a papermaking machine, a substantial suction-eifect is produced at the trailing edge of the roller 1C, .thatis, the uprising portion of .the arcuate surface of the rollerC which is just turning .awayupwardsrfrom the carrier band B.

The above mentioned tsuction effect, which is greater with an imperforate roller C than with a perforated roller, operates on the watery pulp in theregion G of give of the carrier band A, and thisnotonlyensures free forward flowrofzthe pulp toward the nip between the slice '1 or the like and the "carrier band A, but also materially assists upward flow .of water-from. the watery pulp through the upper forming B and up the-slice J or the like for removal.

It is desirable as previously mentioned to arrange the pressing element I close to theimperforate roller C, because the suction efiectabove referred to may be so great as to lift the upper band -B and cause malformation of the web.

The give of the carrier band A is more apparent when dewatering a second layer, ,i.e., when there is already 2. formed or-partly-formed layer on the carrier Inthis case the formed layer acts to a great sition G where the said band'gives, a degree of pressure builds up which enhances the .upwards formation effect. A machine for making paper or paper board orsimilar fibrous product havingtwoor more plies is also described in the'parent'PatentNo. 2,821,120, above referred to,

that is, a machine in which a single traveling wire or carrier bandis commonto two'or more dewatering units adapted for upward removal of water. In accordance with this invention one or more of the dewatering units for forming subsequent layerscould use an imperforate roller as herein described.

Instead of using a slice I, or in addition to a slice,

for removing the upwardly flowing'water, a suction box may be arranged downstream'f-rorn the impertorate roll- .er,;so that upwards water-removalmay' be increased. A

assists perforate roller may be substantially enclosed by the periphery of the roller and side plates, the downstream end of said closure being provided by a slice. In this case an air current is developed across the surface of the enclosed section of the upper band in the downstream direction, such air stream entering through gaps between the side plates and the periphery of the roller, passing across the surface of water within the enclosure and thence up the slice. By this arrangement the air current acts to entrain the water and direct it towards and up the slice.

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

I claim as my invention:

1. A paper making machine having a bottom foraminous forming wire, a top foraminous forming wire, means for advancing the wires in the same direction, an imperforate roller pressing the top wire against the bottom wire along an unsupported span of the top wire, means for feeding a layer of stock between the wires under the imperforate roller and maintaining a pond of stock between the Wires under the roller subjected to the pressure of the roller, said pressure of the roller and said pond of stock deflecting the bottom wire, means downstream from the imperforate roller for removing water from the top wire, and said top wire having an open draw between the imperforate roller and said means for removing water which draw in subjected to the influence of a current of air produced by the ascending side of the irnperforate roller for assisting the discharge of water through the top wire for feeding to said means for removing water.

2. A paper making machine which comprises a looped bottom foraminous forming wire, a looped top foraminous forming wire, an imperforate directing roller in the loop of the top forming wire engaging and guiding said wire against the bottom forming wire, a slice in the loop of the top forming wire in closely spaced relation downstream from said directing roller, said directing roller and slice coacting to provide .a wedge gap between the wires, means for feeding stock against the descending side of the imperforate roller into said wedge gap, means pressing said imperforate roller toward the bottom wire to subject stock in the pond in said gap to pressure un- 6 der said roller, and said top wire having an open iun between the imperforate roller and the slice subjected to a pulling effect created by the ascending side of the imperforate roller which assists the removal of water upwardly through the top wire and over said slice.

3. A paper-making machine which comprises a pair of first and second opposed foraminous forming wires each having coacting forming runs advancing in the same direction, water removal means pressing said wires together, an imperforate directing roller engaging and guiding said first wire in advance of the pressing means to direct the first wire for deflecting the second wire to form a wedge-shaped gap under the directing roller between the wires, means for feeding watery pulp into said gap, and said imperforate directing roller rotating in the same direction of travel as the wires to pump water through said first wire as the first wire moves away from the roll and to feed water to said water removal means for dewatering the stock in the gap.

4. The method of making a fibrous web which comprises feeding watery stock into a nip between :a bottom forming wire and a top forming wire trained around an impervious directing roll, pressing said direct-ing roll toward said bottom wire to subject the stock in the nip to pressure, advancing the wires in the same direction under said roll with the stock therebetween, releasing the pressure on said stock between the wires as the top wire leaves the directing roll, rotating said roll at a sufliciently fast rate to pull water through the top wire from said stock between the wires and initiate formation of a web from said stock on the top wire and removing water from the top wire.

References Cited in the file of this patent UNITED STATES PATENTS 1,666,472 Seybold et al. Apr. 17, 1928 1,742,991 Heys Jan. 7, 1930 1,864,784 Wiener et al June 28, 1932 2,141,393 Hutchins Dec. 27, 1938 2,730,933 Reynolds Jan. 17, 1956 2,821,120 Thomas et al Jan. 28, 1958

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