US3671388A - Paper machine including a horizontal suction forming cylinder having multiple dewatering areas thereon - Google Patents

Abstract

The paper machine comprises a horizontal cylinder, a slurry feed box opening onto the top side of the cylinder and the upper rim of the feed slice of which has been continued in order to form a roof-like upper lip between the feed slice and a feed roll placed on the cylinder at an approximate distance from the feed box in the direction of slurry flow, an endless felt or wire running from the feed roll along the cylinder towards the lower part of the same, an appropriate number of guiding and tension rolls for conducting said felt or wire back to the feed roll, a suction box or suction roll placed on the side of the feed roll opposite to that facing the cylinder and at the point where the slurry web and felt or wire depart from the cylinder surface, and possibly a compressed air box or equivalent placed above the felt or wire and after the feed roll, as seen in the direction of travel of the wire, approximately coincident with the gap remaining between the roof-like upper lip of the feed box and the wire. The horizontal cylinder is a suction cylinder which has therein a suction zone extending substantially from and including the upper roof-like lip continuously to the suction box or suction roll. The upper roof-like lip and suction cylinder form a first drying area for the slurry to form a partially dewatered web while the belt thereafter contacts the web against the surface of the suction cylinder over a major portion of the descending surface of the suction cylinder to form a second drying area in which suction and centrifugal force act upon the web to remove additional water.

Description

June 20, 1972 E. A. NYKOPP 3,671,388

LUDING A HORIZONTAL SUCTION F0 PAPER MACHINE INC RMING CYLINDER HAVING MULTIPLE DEWATERING AREAS THEREON Fnea July 18, 1969 2 Sheets Sheet l Fig. 1

INVENTOE ERIK A. NYKOPF BY ATTORNEYS June 20, 1972 NYKQPP 3,671,388

PAPER MACHINE INCLUDING A HORIZONTAL SUCTION FORMING CYLINDER HAVING MULTIPLE DEWATERING AREAS THEREON fi'lled July 18, 1969 2 Sheets-Sheet 2 iNVENTOE ERIK ANYKOPF BYI 5 'ATTOIZNEYS United States Patent ice PAPER MACHINE INCLUDING A HORIZONTAL SUCTION FORMING CYLINDER HAVING MUL- TIPLE DEWATERING AREAS THEREON Erik A. Nykopp, Tampere, Finland, assignor to Oy Tampella AB, Tampere, Finland Filed July 18, 1969, Ser. No. 843,144 Int. Cl. D211? 1 /60; D21]: 1/06 US. Cl. 162-304 7 Claims ABSTRACT OF THE DISCLOSURE The paper machine comprises a horizontal cylinder, a slurry feed box opening onto the top side of the cylinder and the upper rim of the feed slice of which has been continued in order to form a roof-like upper lip between the feed slice and a feed roll placed on the cylinder at an appropriate distance from the feed box in the direction of slurry flow, an endless felt or wire running from the feed roll along the cylinder towards the lower part of the same, an appropriate number of guiding and tension rolls for conducting said felt or wire back to the feed roll, a suction box or suction roll placed on the side of the feed roll opposite to thatfacing the cylinder and at the point where the slurry web and felt or wire depart from the cylinder surface, and possibly a compressed air box or equivalent placed above' the felt or wire and after the feed roll, as seen in the direction of travel of the wire, approximately coincident with the gap remaining between the roof-like upper lip of the feed box and the wire. The horizontal cylinder is a suction cylinder which has therein a suction zone extending substantially from and including the upper roof-like lip continuously to the suction box or suction roll. The upper roof-like lip and suction cylinder form a first drying area for the slurry to form a partially dewatered web while the belt thereafter contacts the web against the surface of the suction cylinder over a major portion of the descending surface of the suction cylinder to form a second drying area in which suction and centrifugal force act upon the web to remove additional water.

BACKGROUND OF THE INVENTION Field of the invention The present invention concerns a paper machine in which a paper web is formed between a revolving cylinder and an endless felt or wire arranged to lap its surface and which units may be provided, if desired, in multiple number in succession for the purpose of'manufacturing a paper web of greater thickness.

Description of prior art In the British Pat. No. 1,019,449 a compound paper machine and its unit have been described, comprising a horizontal row of web-forming units, each unit consisting of a horizontal cylinder with a flow box opening onto it, these boxes introducing slurry onto the cylinder surface, of a feed roll placed'upon the cylinder at an appropriate distance in the direction of slurry flow, of a companion roll placed to meet the cylinder at a point opposite to the feed roll on the other side of the cylinder, and of a felt or wire net belt running from the feed roll along the lower surface of the cylinder to the companion roll and which rims as an endless loop from one webforming unit to the next and back to the first unit again.

However, a paper machine system of this kind is only suitable for use in multiple layer cardboard machines of comparatively low speed. With this machine no high speeds can be attained because initial forming of the web 3,671,388 Patented June 20, 1972 takes place on an open arced surface. As a consequence,

centrifugal force would, at high speeds, hurl fibres and water from the upper surface of the slurry layer away from the cylinder even in the event that suction would be applied to the interior of the cylinder.

In the US. Pat. 3,132,990 a paper machine has been described comprising a horizontal cylinder, a slurry feed box opening onto the ascending upper surface of the cylinder, a feed box placed above the cylinder ahead of the slurry feeding point and which cooperates with a suction roll placed under the cylinder, to guide an endless wire so that it laps part ofthe cylinder surface, and guiding rolls for returning the wire from the suction roll to the feed roll. In this paper machine the lower and/or alternatively upper wall of the feed slice in the feed box are displaceable in their longitudinal direction in the direction towards the press nip for the purpose of regulating the slurry flow feed into the press nip. This machine has the same drawback as that described in the abovementioned British Pat. No. 1,019,449, and if the feed slice is placed too close to the press nip, the excess water does not have time to be drawn into the cylinder, instead of which it flows backwards along the cylinder surface or is thrown off by centrifugal force. The fiow also tends to run off the ends of the cylinder between the wire and cylinder immediately after the feed roll. This occurs particularly at high speeds, over about 250 m./min. The initial dewatering, which is highly important, is also uneven in the crossmachine direction because the endless wire may stretch non-uniformly. Furthermore, the rate of dewatering is not controllable at high running speeds. It is impossible with a paper machine of this kind to produce high-quality paper, and which is uniform in re spect of its base weight and fibre distribution, at high speeds, above about 250 m./min. The same is true for the second embodiment presented in the said US. Patent, which includes means for shaping the press gap by the aid of elements placed above the wire, in which connection the :slurry feed box has been placed to open onto the ascending upper surface of the cylinder. A great proportion of the slurry flow will be thrown off the cylinder surface or will run downwardly away from the forming area, in this case along the suitable shaped, inclined upper surface of the forming box.

SUMMARY OF THE INVENTION The invention concerns a paper machine comprising a horizontal cylinder, a slurry feed box opening onto this cylinder for the feeding of slurry onto the ascending upper surface of said cylinder, on the said cylinder at appropriate distance from the said slurry feed box in the direction of slurry flow a feed roll, and endless flexible wall running from this feed roll along the surface of said cylinder towards the lower part of the cylinder, an appropriate number of guiding and tension rolls which conduct the said flexible wall back to the said feed roll, and a suction device, which is located on the side opposite to the cylinder of the said feed roll at the point where the slurry web and the said flexible wall are separated from the surface of said cylinder.

The aim of the present invention is to afford comparatively inexpensive equipment for the manufacturing, employing high speeds, of high-quality paper and which is uniform in respect of its base weight and fibre distribution, e.g. newsprint.

A further object of the invention is to afford a compound paper machine comprising a plurality of mutually cooperating devices according to the invention for the purpose of forming a multilayer slurry web.

In a paper machine according to the invention, the upper rim of the feed slice of the slurry feed box has the feed slice and feed roll.

When the slurry flow arrives on the surface of the cylinder, water is drawn from it, and by action of the rooflike, appropriately shaped upper lip a comparatively long enclosed area is produced where the hydraulic differential pressure between the upper surface of the slurry web which is formed and the suction cylinder is as high as possible, which circumstance has an equalizing effect with regard to base weight because the slurry tends to flow to points where filtration is easy, that is, to points where fibres are less abundant. The influence of centrifugal force has also been eliminated at the most critical of all webforming phases, namely, in its initial phase. Furthermore, the dewatering rate of slurry within the long enclosed area of first drying area can be regulated With the aid of the upper lip, the shape of which is changeable as may be desired. It is also possible to seal the edges of the forming area roofed over by the upper lip and thus to prevent the water from running off the cylinder at its ends. The web arrives in the press nip between the endless wire and the cylinder, as viewed from the side, as a comparatively narrow flow and which is of uniform base weight, and in a condition of considerably higher consistency than in the initial part of the forming area. The dewatering rate is adjustable by means of the vacuum in the suction device, of the profile of the upper lip, and by changing the gap between the trailing end of the upper lip and the cylinder. The partly dried web coming from under the roof-like upper lip is no longer highly susceptible to effects of centrifugal force. As a result, it is possible with a device according to the invention to produce a slurry web at far higher speeds than with devices belonging to previous art, for instance at speeds in excess of about 250 m./min.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is described in closer detail in the following, with reference to the attached drawings, in which FIG. 1 presents a schematic elevational view of a paper machine according to the invention, and FIG. 2 shows a similarly schematic side elevation of a particularly advantageous embodiment of the invention.

FIG. 3 shows a compound paper machine for forming a multilayer slurry web.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the reference numeral 1 indicates the slurry feed box, 2 is the cylinder, 3 is a flexible, porous endless belt which is advantageously an endless wire or felt, 4 is the feed roll, 5 is a suction box, 6 is the roof-like upper lip, 7 is the slurry feed slice, 8 is a pick-up felt, 9 is a pick-up roll, 10 is a save-all, and 11 is a jet pipe for cleaning the cylinder. 7

The slurry flow arrives from the feed slice 7 onto the surface of the cylinder, at which stage water is drawn from it and by virtue of the roof-like upper lip 6 and of seals placed on the sides between the upper lip and the cylinder, an enclosed area or first drying area is formed in which the hydraulic differential pressure between the upper surface of the slurry Web that is being formed and the suction cylinder is as high as possible, whereby favour-' uniform web which was already produced, and reduces the one-sided structure of the web, while at the same time efficient dewatering takes place in two directions. The dewatering region when the paper is between the wire "3' and the cylinder 2 is the second drying area encountered by the paper web as it is formed upon the cylinder 2.

Upon arriving on the lower part of the cylinder, the slurry web is picked off the cylinder with the aid of a suction box 5 or equivalent, to continue its travel upon a plane wire, from which it is taken off, e.g. with the aid of a pick-up arrangement 8, 9 to be conveyed onward for further treatment. At this point the wire 3 is returned to the feed roll 4 over appropriate guiding and tension rolls.

The slurry web may also be carried along with the wire to the next machine, which is a replica of the first machine described above, and from the second machine further to a third machine, etc., depending on the thickness of the slurry web or its number of layers which is desired. In the last machine, the web is picked up from the wire in conventional manner and conveyed onward for further treatment, and the wire is carried back to the feed roll 4 of the first machine.

It has been observed, whenever the web speed exceeds about 250 m./min., that no longer is any water drawn into the suction box of the suction roll, instead of which the water remains in the perforation of the mantle and from which it is hurled out after the suction zone has been passed. It is advantageous for this reason to place the save-all 10 after the suction box 5, and at the same time it serves the purpose of collecting the water coming from the nozzle 11, by means of which the cylinder is flushed.

It is to be understood that dewatering of the web be further augmented on the plane wire run, by providing adjacent to this run and before the pick-up arrangement dewatering elements of a kind previously known in itself, such as suction boxes.

The device presented in FIG. 2 differs from the foregoing in that over the wire 3 and after the feed roll 4 in the direction of travel of the wire there has been placed a compressed air box 12 coincident with the gap remaining between the roof-like upper lip 6 of the feed box 1 and the wire 3. Upon emerging from under the upper lip 6, the slurry web is subjected to the pressure of the air discharging from the compressed air box 12 and through the wire 3, whereby in spite of the influence of centrifugal force the fibres and water in the upper surface of the slurry web cannot be detached from the web and, on the contrary, remain where they are, while at the same time this external pressure aids the dewatering into the suction cylinder 2.

FIG. 3 shows a compound paper machine for making a multilayer paper web. This machine has a first web former A and a second web former B, each web former being of the type shown in FIG. 1. The endless belt C is conducted from the preceding web former A to the feed roll D of the next web former B. After the belt leaves 'web former B, it returns to web former A.

What is claimed is:

1. A web-forming apparatus comprising:

a rotatable, horizontally mounted suction cylinder;

a slurry feed box with a feed slice for depositing slurry upon the ascending surface of said rotatable cylinder, said feed slice having an upper lip extending over said ascending surface and in close proximity thereto, said upper lip solely with said ascending surface forming a substantially enclosed area between said lip and said ascending surface of said cylinder for containing said deposited slurry, said enclosed area forminga first drying area wherein the suction of said suction cylinder removes a portion of the water in said slurry to form a partially dewatered Web;

a flexible, endless belt positioned to contact said partially dewatered web at a point immediately adjacent to said upper lip, said contact being made as said partially dewatered web emerges from under said upper lip, said belt maintaining said partially dewatered web against surface of said suction cylinder over a major portion of the descending surface of said suction cylinder, providing a second drying area in which the suction and centrifugal force upon said partially dewatered web removes additional water from said partially dewatered web in two directions; and

a suction box disposed on the side of said endless belt opposite said partially dewatered web and located at substantially the point at which said endless belt and said partially dewatered web are separated from said cylinder wherein said suction box provides a force to separate said partially dewatered web from said cylinder, the suction cylinder having therein means defining a suction zone extending substantially from and including the first drying area, through the second drying area, and substantially to the suction box where the web is separated from the cylinder.

2. The web-forming apparatus of claim 1 additionally comprising:

an air blowing means positioned on the side of said endless belt which does not contact said partially dewatered web, said air blowing means being further positioned to permit air to be blown through said endless belt and against said partially dewatered web as it emerges from under said upper lip, said air blowing means for providing a force to maintain said partially dewatered web in contact with said suction cylinder when said partially dewatered web upon said cylinder is between said upper lip and the point of contact with said endless belt.

3. The web-forming apparatus of claim 1 wherein said endless belt is comprised of wire.

4. The web-forming apparatus of claim 1 wherein the endless belt is comprised of felt.

5. The web-forming apparatus of claim 1 wherein said suction cylinder has a suction opening coextensive with the portion of contact of said partially dewatered web with said suction cylinder.

6. The web-forming apparatus of claim 1 additionally comprising:

a Water spraying means for spraying water upon the surface of said cylinder over the portion of said cylinder not containing said partially dewatered web; and

a collection means for collecting said sprayed water.

7. The web-forming apparatus of claim 1 additionally comprising:

at least one additional rotatable, horizontally mounted suction cylinder;

an additional slurry feed box for each additional cylinder, each said additional feed box with a feed slice for depositing slurry upon the ascending surface of the additional cylinder, said feed slice having an additional upper lip extending therefrom, said upper lip forming an enclosed area between said lip and said additional cylinder for containing the additionally deposited slurry, said enclosed area forming a first drying area for each said additional cylinder wherein the suction of said suction cylinder removes a portion of the water in said additionally deposited slurry to form an additional partially dewatered web; and

wherein said endless belt is positioned to additionally References Cited UNITED STATES PATENTS 2,772,606 12/1956 Kelly 162-276 2,995,186 8/1961 De Montigny 162-317 X 3,072,180 1/1963 Jodrey 162-347 X 3,111,454 11/1963 Tucker et al. 162-297 3,132,990 5/1964 Trufitt 162-317 3,321,360 5/1967 Holt 162-317 X 3,472,733 10/1969 Holt 162-214 X 3,485,715 12/196'9 Kobayashi 162-304 S. LEON BASHORE,

Primary Examiner A. DANDREA, 111., Assistant Examiner US. Cl. X.R.

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