Method of forming a multi-ply paper web in a twin- wire former and twin-wire former for carrying out the method

Claim 3

The method as defined in claim 1, further including the steps of: pre-dewatering the first stock jet and the further stock jets, with the exception of the last stock jet, at the first wire.

Claim 4

The method as defined in claim 1 or 2, further including the steps of: performing the pre-dewatering at the first wire essentially by means of the inherent static and dynamic pressure of the liquid columns of the stock jets.

Claim 5

The method as defined in claim 1 or 2, further including the steps of: controlling the pre-dewatering at the first wire by dewatering elements arranged at a rear side of the wire.

Claim 6

The method as defined in claim 1, further including the steps of: subjecting at least the last stock jet and the web already formed at least from the first stock jet to an increasing dewatering pressure at a curved path possessing increasing curvature.

Claim 7

The method as defined in claim 1, further including the steps of: maintaining the stock jets separated from one another by essentially completely rigid partition elements until deposition thereof at the first and second endless revolving wires.

Claim 8

The method as defined in claim 1, further including the steps of: controlling guiding the individual stock jets by partition elements located externally of the outlet openings.

Claim 11

The method as defined in claim 1, wherein: said rigid partition walls serve to establish and maintain different velocity and pressure conditions in respective passageways within said headbox which are at least partially formed by said rigid partition walls, in order to thereby enable selective deposition of the separate stock jets at predetermined locations externally of the outlet openings of the headbox, so as to control the dewatering of the stock jets.

Claim 12

The method as defined in claim 1, further including the steps of: influencing the outlet velocity of said related stock jet such that the same is higher than the outlet velocity of a precedingly deposited stock jet.

Claim 13

The method as defined in claim 1, further including the steps of: influencing the outlet velocity of the related stock jet such that the same is higher than the velocity of travel of said first wire.

Claim 14

A twin-wire former for a papermaking machine for forming a multi-ply paper web, comprising: headbox means; at least two mutually separated stock infeed means for a stock suspension and a corresponding number of outlet openings provided for said headbox means; boundary walls for bounding said outlet openings; said boundary walls extending over the width of the headbox means and substantially parallel to the direction of flow of the stock suspension; at least two partition elements arranged between stock jets of the stock suspension for maintaining separate from one another the stock jets over a predetermined path downstream of the outlet openings; at least two essentially rigid partition walls extending at least up to the region of said outlet openings of the headbox means; a respective one of each of said two essentially rigid partition walls being operatively associated with a respective one of said two partition elements; means pivotably mounting at least one of said two essentially rigid partition walls to be adjustable in position; means for fixing said at least one adjustable essentially rigid partition wall in a desired adjusted position essentially corresponding to a desired velocity of a related stock jet which is bounded by said one adjustable essentially rigid partition wall to ensure for a predetermined outlet velocity of such related stock jet from the related outlet opening of the headbox means; a first endless revolving wire; a second endless revolving wire; a dewatering roll; said first and second endless revolving wires conjointly at least partially wrapping about said dewatering roll; said first and second endless revolving wires forming at their run on location at the dewatering roll a converging space for receiving a paper web which is in the process of being formed; means defining a pre-dewatering path; said first wire prior to contact with the dewatering roll being guided over said pre-dewatering path; said pre-dewatering path including a starting portion; said headbox means having at least one of its outlet openings located at said starting portion; said partition elements cooperating with said starting portion of the pre-dewatering path in a manner such that only the first stock jet neighbouring the first wire impinges at the first wire; and at least the last partition element possessing a length such that the last stock jet supported by said last partition element is directly directed into the converging space between the wires.

Claim 15

A twin-wire former for a papermaking machine for forming a multi-ply paper web, comprising: headbox means; at least two mutually separated stock infeed means for a stock suspension and a corresponding number of outlet openings provided for said headbox means; boundary walls for bounding said outlet openings; said boundary walls extending over the width of the headbox means and substantially parallel to the direction of flow of the stock suspension; at least two partition elements arranged between stock jets of the stock suspension for maintaining separate from one another the stock jets over a predetermined path downstream of the outlet openings; at least two essentially rigid partition walls extending at least up to the region of said outlet openings of the headbox means; a respective one of each of said two essentially rigid partition walls being operatively associated with a respective one of said two partition elements; means pivotably mounting at least one of said two essentially rigid partition walls to be adjustable in position; means for fixing said at least one adjustable essentially rigid partition wall in a desired adjusted position essentially corresponding to a desired velocity of a related stock jet which is bounded by said one adjustable essentially rigid partition wall to ensure for a predetermined outlet velocity of such related stock jet from the related outlet opening of the headbox means; a first endless revolving wire; a second endless revolving wire; a dewatering roll; said first and second endless revolving wires conjointly at least partially wrapping about said dewatering roll; said first and second endless revolving wires forming at their run on location at the dewatering roll a converging space for receiving a paper web which is in the process of being formed; means defining a pre-dewatering path; said first wire prior to contact with the dewatering roll being guided over said pre-dewatering path; said pre-dewatering path including a starting portion; said headbox means having at least one of its outlet openings located at said starting portion; said partition elements cooperating with said starting portion of the pre-dewatering path in a manner such that only the first stock jet neighbouring the first wire impinges at the first wire; and at least the last partition element possessing a length such that the last stock jet supported by said last partition element is directly directed into the converging space between the wires.

Claim 16

The twin-wire former as defined in claim 12, further including: a breast roll for guiding the first wire in an essentially linear path of travel through the pre-dewatering path.

Claim 17

The twin-wire former as defined in claim 13, wherein: said means defining said pre-dewatering path including means located at the pre-dewatering path below the first wire for influencing the dewatering action.

Claim 18

The twin-wire former as defined in claim 14, wherein: said influencing means comprise wire table means.

Claim 19

The twin-wire former as defined in claim 14, wherein: said influencing means comprise suction ledge means.

Claim 20

The twin-wire former as defined in claim 14, wherein: said influencing means comprise suction box means.

Claim 21

The twin-wire former as defined in claim 14, wherein: said influencing means produce increasing negative pressure.

Claim 22

The twin-wire former as defined in claim 13 or 14, further including: a wire shoe having a convex curved surface; said wire shoe being arranged forwardly of said dewatering roll below the first wire; said convex curved surface having a curvature which is less than the curvature of an outer surface of the dewatering roll; and said convex curved surface being at least partially wrapped by said second wire.

Claim 23

The twin-wire former as defined in claim 12, wherein: said dewatering roll comprises a forming roll about which there is guided the first wire at the pre-dewatering path.

Claim 24

The twin-wire former as defined in claim 12, wherein: said dewatering roll comprises a solid roll.

Claim 25

The twin-wire former as defined in claim 12, wherein: said dewatering roll comprises a roll containing grid means arranged at the roll surface.

Claim 26

The twin-wire former as defined in claim 22, further including: a suction box provided for said dewatering roll

Claim 27

The twin-wire former as defined in claim 12, further including: a positionally adjustable deflection roll for influencing the converging space; and said second wire being guided by said deflection roll before joining-up with the first wire.

Claim 28

The twin-wire former as defined in claim 12, wherein: said partition elements are structured as rigid partition surfaces between the individual stock jets.

Claim 29

The twin-wire former as defined in claim 25, wherein: said fixing means comprises externally located adjustment means for adjusting the partition surfaces so as to assume a predetermined position.

Claim 30

The twin-wire former as defined in claim 25, wherein: said partition surfaces are structured with respect to their pivotably mounting means such that they can be exchanged from externally of the headbox means.

Claim 31

The twin-wire former as defined in claim 25, wherein: said partition surfaces possess a curved configuration in accordance with wire guides.

Claim 32

The twin-wire former as defined in claim 25, wherein: said partition surfaces are structured to possess at least in part a surface structure which produces a microturbulence.

Claim 33

The twin-wire former as defined in claim 25, wherein: at least two of the outlet openings of the headbox means comprise neighbouring outlet openings of a multi-ply headbox; the neighbouring boundary walls of said two outlet openings being formed by a common partition wall; and a partition element directly merging at said common partition wall.

Claim 34

The twin-wire former as defined in claim 30, especially for a double-ply web, wherein: a single partition surface is provided which is rigidly connected with the common partition wall; and means for adjusting both outer boundary walls of the outlet openings for influencing the stock jet.

Claim 35

The twin-wire former as defined in claim 30, especially for a triple ply web, wherein: the partition wall neighbouring the first wire and the partition surface are substantially rigid structures; means for pivotably mounting the second partition surface and the related partition wall; and means for adjusting outer boundary walls of the headbox means.

Claim 36

The twin-wire former as defined in claim 32, wherein: said means for pivotably mounting said second partition surface and the related partition wall enables adjustment of said second partition surface and said related partition wall.

Claim 37

The twin-wire former as defined in claim 30, especially for a triple-ply web, wherein: both of the partition walls and/or the partition surfaces are structured as a channel-shaped unit connected at its outer edges.

Claim 38

The twin-wire former as defined in claim 25, especially for a triple-ply web, wherein: the outlet opening of the last stock jet located downstream of the outlet openings for two other of said stock jets defining first and second stock jets is arranged at a location at which there has not yet been terminated the forming of the web from the second stock jet.

Claim 39

The twin-wire former as defined in claim 35, wherein: the partition element for separating the second stock jet and the last stock jet begins at a location downstream of the outlet openings for the first stock jet and the second stock jet.

Claim 40

The twin-wire former as defined in claim 12, wherein: said rigid partition walls serve to establish and maintain different velocity and pressure conditions in respective passageways within said headbox which are at least partially formed by said rigid partition walls, in order to thereby enable selective deposition of the separate stock jets at predetermined locations externally of the outlet openings of the headbox, so as to control the dewatering of the stock jets.

Claim 41

The twin-wire former as defined in claim 12, wherein: said partition elements possess a length sufficient to preclude commingling of any of the stock jets within the headbox means.

Claim 42

A twin-wire former for a papermaking machine for forming a multi-ply paper web, comprising: headbox means; at least two mutually separated stock infeed means for a stock suspension and a corresponding number of outlet openings provided for said headbox means; boundary walls for bounding said outlet openings; said boundary walls extending over the width of the headbox means and substantially parallel to the direction of flow of the stock suspension; at least one partition element arranged between stock jets of the stock suspension for maintaining separate from one another the stock jets over a predetermined path downstream of the outlet openings; at least one essentially rigid partition wall extending at least up to the region of the outlet openings of said headbox means; said at least one essentially rigid partition wall being operatively associated with said at least one partition element; means pivotably mounting said essentially rigid partition wall to be adjustable in position; means for fixing said at least one adjustable essentially rigid partition wall in a desired adjusted position essentially corresponding to a desired velocity of a related stock jet which is bounded by said one adjustable essentially rigid partition wall to ensure for a predetermined outlet velocity of such related stock jet from the related outlet opening of the headbox means; a first endless revolving wire; a second endless revolving wire; a dewatering roll; said first and second endless revolving wires conjointly at least partially wrapping about said dewatering roll; said first and second endless revolving wires forming at their run-on location at the dewatering roll a converging space for receiving a paper web which is in the process of being formed; means defining a pre-dewatering path; said first wire prior to contact with the dewatering roll being guided over said pre-dewatering path; said pre-dewatering path including a starting portion; said headbox means having at least one of its outlet openings located at said starting portion; said partition element being structured and guided such that at the starting portion of the pre-dewatering path only the first stock jet neighbouring the first wire impinges at the first wire; and said partition element possessing a length such that a last stock jet supported by said partition element is directly directed into the converging space between the wires.

Claim 43

A twin-wire former for a papermaking machine for forming a multi-ply paper web, comprising: headbox means; at least two mutually separated stock infeed means for a stock suspension and a corresponding number of outlet openings provided for said headbox means; boundary walls for bounding said outlet openings; said boundary walls extending over the width of the headbox means and substantially parallel to the direction of flow of the stock suspension; at least one partition element arranged between stock jets of the stock suspension for maintaining separate from one another the stock jets over a predetermined path downstream of the outlet openings; at least one essentially rigid partition wall extending at least up to the region of the outlet openings of said headbox means; said at least one essentially rigid partition wall being operatively associated with said at least one partition element; means pivotably mounting said essentially rigid partition wall to be adjustable in position; means for fixing said at least one adjustable essentially rigid partition wall in a desired adjusted position essentially corresponding to a desired velocity of a related stock jet which is bounded by said one adjustable essentially rigid partition wall to ensure for a predetermined outlet velocity of such related stock jet from the related outlet opening of the headbox means; a first endless revolving wire; a second endless revolving wire; a dewatering roll; said first and second endless revolving wires conjointly at least partially wrapping about said dewatering roll; said first and second endless revolving wires forming at their run-on location at the dewatering roll a converging space for receiving a paper web which is in the process of being formed; means defining a pre-dewatering path; said first wire prior to contact with the dewatering roll being guided over said pre-dewatering path; said pre-dewatering path including a starting portion; said headbox means having at least one of its outlet openings located at said starting portion; said partition element being structured and guided such that at the starting portion of the pre-dewatering path only the first stock jet neighbouring the first wire impinges at the first wire; and said partition element possessing a length such that a last stock jet supported by said partition element is directly directed into the converging space between the wires.