WO2012041392A1 - Device and method for manufacturing a web consisting of multiple layers - Google Patents

Device and method for manufacturing a web consisting of multiple layers Download PDF

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Publication number
WO2012041392A1
WO2012041392A1 PCT/EP2010/064658 EP2010064658W WO2012041392A1 WO 2012041392 A1 WO2012041392 A1 WO 2012041392A1 EP 2010064658 W EP2010064658 W EP 2010064658W WO 2012041392 A1 WO2012041392 A1 WO 2012041392A1
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WO
WIPO (PCT)
Prior art keywords
layer
partial
ply
layers
forming
Prior art date
Application number
PCT/EP2010/064658
Other languages
French (fr)
Inventor
Hannu Turpeinen
Teuvo Virkkunen
Original Assignee
Metso Paper, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Metso Paper, Inc. filed Critical Metso Paper, Inc.
Priority to PCT/EP2010/064658 priority Critical patent/WO2012041392A1/en
Publication of WO2012041392A1 publication Critical patent/WO2012041392A1/en

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F9/00—Complete machines for making continuous webs of paper
    • D21F9/003—Complete machines for making continuous webs of paper of the twin-wire type
    • D21F9/006—Complete machines for making continuous webs of paper of the twin-wire type paper or board consisting of two or more layers
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
    • D21F11/02—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines of the Fourdrinier type
    • D21F11/04—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines of the Fourdrinier type paper or board consisting on two or more layers

Definitions

  • the invention relates to a device and method for
  • a web consisting of at least three layers, e.g. a board consisting of multiple layers.
  • Fig. 7 A typical board consisting of multiple layers, which will be referred to as multilayerboard in the following, is shown in Fig. 7.
  • the board shown in this figure is a white lined chipboard consisting of four layers and two coatings.
  • the multilayerboard comprises a middle ply 11, an undertop ply 12, a top ply 13 and a back ply 14.
  • the undertop ply 12 and the back ply 14 are provided directly on the middle ply 11 on opposite sides of the middle ply 11.
  • the middle ply 11 is sandwiched by the undertop ply 12 and the back ply 14.
  • the top ply 13 is provided on the undertop ply 12 on the side opposite to the side facing the middle ply 11. Furthermore, onto the sides of the top ply 13 and the back ply 14 being free of a covering layer, a coating 15, 16 is applied.
  • the middle ply 11 is usually made of old corrugated
  • OCC container pulp
  • groundwood pulp GW
  • PGW pressure groundwood pulp
  • broke or the like.
  • the undertop ply 12 is typically made of deinked (recycled) pulp, white ledger,
  • CTMP chemithermomechanical pulp
  • GW GW
  • chemithermomechanical pulp For the top ply 13, bleached hardwood pulp, bleached softwood pulp, white ledger, or the like are used, whereas, for the back ply 14, deinked (recycled) pulp, chemical pulp, CTMP, broke, OCC or the like are used.
  • the middle ply 11 is thicker than any other layer of the multilayer board in order to provide a sufficient rigidity of the board.
  • the middle ply 11 serves as a support layer.
  • the structure of a generic device for manufacturing the above-described multilayer board is shown in Fig. 8.
  • the device comprises a hybrid former 17 and three fourdrinier former 18, 19, 110.
  • the hybrid former 17 forms the middle ply 11, the fourdrinier former 18 forms the undertop ply 12, the fourdrinier former 19 forms the back ply 14 and the fourdrinier former 110 forms the top ply 13.
  • the middle ply 11 and the undertop ply 12 are guided to a first couching roll 111 with which the two plies 11, 12 are couched together.
  • the resulting two-layer web is guided to a second couching roll 112 with which the back ply 14 and the two- layer web consisting of middle ply 11 and undertop ply 12 are couched together.
  • the resulting web which now consists of three layers is guided to a third couching roll 113 couching the top ply 13 onto the undertop ply 12.
  • a third couching roll 113 couching the top ply 13 onto the undertop ply 12.
  • the object of the invention to provide a device and method for manufacturing a web consisting of at least three layers, wherein one of the layers is a support layer being heavier than any other layer of the web, at a higher production rate.
  • the object of the invention is solved by a device according to claim 1 and by a method according to claim 7.
  • the device comprises a first forming section adapted to form a first partial layer of the support layer, a second forming section adapted to form a second partial layer of the support layer, and a joining section for joining the first partial layer and the second partial layer both being made from stock having identical composition together, so as to form a material-homogeneous support layer. That is, the essence of the invention is to provide a material-homogeneous support layer by joining two partial layers made of the same stock together.
  • a first and a second forming section for forming a first and a second partial layer of the support layer and joining the same to one material-homogeneous layer instead of forming the support layer directly, it is possible to provide a faster dewatering of the support layer, for instance. More precisely, it is possible to dewater the two partial layers faster than one single support layer having a thickness which is the sum of the thicknesses of the two partial layers .
  • the expression "material-homogeneous" means that the support layer formed from two partial layers made from the same stock has the structure of a support layer formed by a single thick layer, so that it is not possible to distinguish the layers from each other.
  • the support layer formed by the two partial layers does not comprise a boundary between the partial layers .
  • the first forming section may be adapted to simultaneously form a first covering layer on one side of the first partial layer of the support layer and the second forming section may be adapted to simultaneously form a second covering layer on one side of the second partial layer of the support layer.
  • the joining section has to be adapted to join the first partial layer and the second partial layer at the sides of the partial layers both free of covering layer together, in order to achieve a material-homogenous support layer.
  • the first forming section comprises a two- layer headbox and a hybrid former.
  • the second forming section may comprise a two- layer headbox and a hybrid former.
  • the second forming section may comprise a two- layer headbox and a hybrid former.
  • other suitable arrangements are also possible for forming two material layers upon each other.
  • the joining section may be adapted to couch the first partial layer and the second partial layer together so as to form the
  • a particular advantageous formation of the device may comprise a further forming section having a one-layer headbox and a fourdrinier former or having a further two- layer headbox and a hybrid former, and may be adapted to form a further covering layer on at least one of the first covering layer and the second covering layer.
  • the method for manufacturing a web consisting of multiple layers, wherein one of the layers is a support layer being heavier than any other layer of the web comprises the steps of forming a first partial layer of the support layer, forming a second partial layer of the support layer, and joining the first partial layer and the second partial layer both being made from stock having identical
  • compositions together so as to form a material-homogeneous support layer.
  • a first covering layer may be simultaneously
  • a second covering layer may be simultaneously provided on one side of the second partial layer of the support layer. Furthermore, during joining the first partial layer and the second partial layer together, the first partial layer and the second partial layer may be joined together at the sides of the partial layers free of covering layer.
  • the first partial layer and the second partial layer are joined together by couching.
  • the method may further comprise the step of forming a further covering layer on at least one of the first covering layer and the second covering layer.
  • Fig. 1 shows a cross section of a multilayerboard
  • FIG. 2 shows a non-limiting example of the device for manufacturing the multilayerboard shown in Fig. 1 ;
  • Fig. 3 shows a cross section of a multilayerboard
  • Fig. 4 shows a non-limiting example of the device for manufacturing the multilayerboard shown in Fig. 3;
  • Fig. 5 shows a cross section of a multilayerboard
  • Fig. 6 shows a non-limiting example of the device for manufacturing the multilayerboard shown in Fig. 5;
  • Fig. 7 shows a cross section of a multilayerboard according to prior art
  • Fig. 8 shows a device for manufacturing the multilayerboard shown in Fig . 7.
  • FIG. 1 shows a cross section of a multilayerboard
  • the multilayerboard manufactured by the device and method according to the invention comprises a middle ply 1, an undertop ply 2, a top ply 3 and a back ply 4, wherein the undertop ply 2 and the back ply 4 are provided on the middle ply 1 on opposite sides of the middle ply 1 so that the middle ply 1 is sandwiched by the undertop ply 2 and the back ply 4.
  • the top ply 3 is provided on the undertop ply 2 on the side opposite to the side facing the middle ply 1. Furthermore, onto the sides of the top ply 3 and the back ply 4 being free of a covering layer, a coating 5, 6 is applied onto the sides of the top ply 3 and the back ply 4 being free of a covering layer.
  • the structure of the multilayerboard manufactured with the device and method according to the invention does not differ from the multilayerboard in the prior art.
  • multilayerboard manufactured with the device and method according to the invention is thicker and heavier than any other ply of the multilayerboard.
  • the multilayerboard is a multilayerboard
  • the device according to the invention comprises a first forming section Fl, a second forming section F2 and a third forming section F3.
  • a non-limiting example of such a device is shown in Fig. 2.
  • Each of the forming sections of the device is adapted to form a specific portion of the multilayerboard, as can be gathered from Fig. 1.
  • forming section Fl forms a first portion 7 of the board
  • forming section F2 forms a second portion 8 of the board
  • forming section F3 forms a third portion 9 of the board, as is shown in Fig. 1.
  • the first portion 7 of the multilayerboard consists of the back ply 4 and of a part of the middle ply 1, the second portion 8 of the
  • multilayerboard consists of the undertop ply 2 and of another part of the middle ply 1 and the third portion 9 consists of the top ply 3. All parts of the middle ply 1 are made from the same stock.
  • the forming sections are structured such that five layers are formed by means of the three forming sections Fl, F2 and F3, wherein two of the five layers - which are referred to as first partial layer pi and second partial layer p2 in the
  • the first forming section Fl and the second forming section F2 each comprise a two-layer headbox and a hybrid former.
  • the two-layer headbox combines two stock flows into one jet leaving the headbox lip.
  • the hybrid former consists of a fourdrinier section and a twin-wire zone, wherein the fourdrinier section precedes the twin- wire zone.
  • the fourdrinier section and the twin-wire zone are identical to The fourdrinier section and the twin-wire zone.
  • the second portion 8 of the multilayerboard shown in Fig. 1 is heavier than the first portion 7 of the multilayerboard. Therefore, the fourdrinier section of the forming section F2 is longer than the fourdrinier section of the forming section Fl .
  • both fourdrinier sections of the forming sections Fl and F2 can have equivalent lengths .
  • the forming section Fl is adapted to simultaneously form the back ply 4 and the first partial layer pi of the middle ply 1 and the forming section F2 is adapted to
  • the first partial layer 1 is formed on the back ply 4 so that the back ply is sandwiched by a wire of the fourdrinier section of the forming section Fl and the first partial layer 1.
  • the jet of stock leaving the headbox of the forming section F2 is structured such that the undertop ply 2 is sandwiched by a wire of the
  • the first partial layer pi and the second partial layer 2 have a side free of a covering layer and not in contact with the wire.
  • the device further comprises a first joining section Jl adapted to couch the first partial layer pi and the second partial layer p2 together so as to form a material homogeneous middle ply 1. That is, after passing the first joining section Jl, a middle ply 1 is formed which - in its characteristics - does not differ from a ply not being formed from two separately formed partial layers as shown in the prior art.
  • the web leaving the first joining section Jl consists of three layers and is guided to the second joining section J2 in which the top ply 3 is provided on the undertop ply 2 of the web. More precisely, the web consisting of middle ply 1, undertop ply 2 and back ply 4 and the top ply 3 are couched together at the second joining section J2.
  • coatings 5 and 6 are provided on the top ply 3 and the back ply 4, respectively.
  • a cross section of a multilayerboard is shown being manufactured with a device and a method according to a second embodiment of the invention.
  • the structure of the multilayerboard shown in Fig. 3 differs from the structure of the multilayerboard shown in Fig. 1 only in that the undertop ply 2 is omitted. That is, the multilayerboard only consists of two portions, namely the first portion 7 consisting of the back ply 3 and of a part of the middle ply 1 and the second portion 8 consisting of the undertop ply 2 and of the other part of the middle ply 1.
  • a device for manufacturing the multilayerboard of Fig. 3 is shown in Fig. 4 and differs from the device shown in Fig.
  • the forming sections are structured such that four layers are formed by means of the two forming sections Fl and F2, wherein two of the four layers - the first partial layer pi and the second partial layer p2 - are made from the same stock and are formed simultaneously with a further layer, i.e. the back ply 4 and the top ply 3, respectively.
  • FIG. 5 A cross section of a multilayerboard being manufactured with a device and a method according to a third embodiment of the invention is shown in Fig. 5.
  • the structure of the multilayerboard shown in Fig. 5 differs from the structure of the multilayerboard shown in Fig. 3 in that an
  • the device in Fig. 6 comprises a further fourdrinier former F4 and a third joining section J3 in order to form the additional back ply 7, i.e. a fourth portion 10 of the board .
  • the essence of the invention is to form the heaviest or thickest layer - the middle layer in the preferred embodiment - by joining the two partial layers pi and p2 together, such that they form one material-homogenous layer, i.e. a single layer which does not comprise a boundary between the partial layers after they have been joined.
  • This heaviest layer is not necessarily a middle layer but may also be one layer of a two layer structure. By forming the heaviest layer in such a manner, it is possible to achieve a higher

Abstract

A device for manufacturing a web consisting of at least three layers, wherein one of the layers is a support layer being heavier than any other layer of the web, comprises a first forming section (Fl) adapted to form a first partial layer (p1) of the support layer, a second forming section (F2) adapted to form a second partial layer (p2) of the support layer, and a joining section (Jl) for joining the first partial layer and the second partial layer (p2) both being made from stock having identical composition together, so as to form a material-homogeneous support layer.

Description

DEVICE AND METHOD FOR MANUFACTURING A WEB CONSISTING OF
MULTIPLE LAYERS
The invention relates to a device and method for
manufacturing a web consisting of at least three layers, e.g. a board consisting of multiple layers.
At present, boards consisting of multiple layers are manufactured by forming each layer separately and joining the separately formed layers afterwards. Each layer is formed by a respective forming unit, e.g. a fourdrinier or hybrid former. A typical board consisting of multiple layers, which will be referred to as multilayerboard in the following, is shown in Fig. 7. The board shown in this figure is a white lined chipboard consisting of four layers and two coatings. As can be gathered from Fig. 7, the multilayerboard comprises a middle ply 11, an undertop ply 12, a top ply 13 and a back ply 14. The undertop ply 12 and the back ply 14 are provided directly on the middle ply 11 on opposite sides of the middle ply 11. In other words, the middle ply 11 is sandwiched by the undertop ply 12 and the back ply 14. The top ply 13 is provided on the undertop ply 12 on the side opposite to the side facing the middle ply 11. Furthermore, onto the sides of the top ply 13 and the back ply 14 being free of a covering layer, a coating 15, 16 is applied.
The middle ply 11 is usually made of old corrugated
container pulp (OCC) , mixed waste, old newsprint,
groundwood pulp (GW) , pressure groundwood pulp (PGW) , broke, or the like. The undertop ply 12 is typically made of deinked (recycled) pulp, white ledger,
chemithermomechanical pulp (CTMP) , GW, or the like. For the top ply 13, bleached hardwood pulp, bleached softwood pulp, white ledger, or the like are used, whereas, for the back ply 14, deinked (recycled) pulp, chemical pulp, CTMP, broke, OCC or the like are used.
As is shown in Fig. 7, the middle ply 11 is thicker than any other layer of the multilayer board in order to provide a sufficient rigidity of the board. In other words, the middle ply 11 serves as a support layer.
The structure of a generic device for manufacturing the above-described multilayer board is shown in Fig. 8. The device comprises a hybrid former 17 and three fourdrinier former 18, 19, 110. The hybrid former 17 forms the middle ply 11, the fourdrinier former 18 forms the undertop ply 12, the fourdrinier former 19 forms the back ply 14 and the fourdrinier former 110 forms the top ply 13. The middle ply 11 and the undertop ply 12 are guided to a first couching roll 111 with which the two plies 11, 12 are couched together. The resulting two-layer web is guided to a second couching roll 112 with which the back ply 14 and the two- layer web consisting of middle ply 11 and undertop ply 12 are couched together. The resulting web which now consists of three layers is guided to a third couching roll 113 couching the top ply 13 onto the undertop ply 12. In manufacturing the board in the above specified way, forming the middle layer or ply 11 is the limiting factor since the basis weight of the same is much higher than the weight of the other layers due to its larger thickness. Therefore, dewatering the middle ply 11 takes time and is highly energy consuming. Consequently, the production rate is largely dependent on the speed at which the middle ply 11 can be manufactured.
Hence, it is the object of the invention to provide a device and method for manufacturing a web consisting of at least three layers, wherein one of the layers is a support layer being heavier than any other layer of the web, at a higher production rate. The object of the invention is solved by a device according to claim 1 and by a method according to claim 7.
Advantageous further formations of the invention are subject of the dependent claims.
According to the invention, the device comprises a first forming section adapted to form a first partial layer of the support layer, a second forming section adapted to form a second partial layer of the support layer, and a joining section for joining the first partial layer and the second partial layer both being made from stock having identical composition together, so as to form a material-homogeneous support layer. That is, the essence of the invention is to provide a material-homogeneous support layer by joining two partial layers made of the same stock together. By using a first and a second forming section for forming a first and a second partial layer of the support layer and joining the same to one material-homogeneous layer instead of forming the support layer directly, it is possible to provide a faster dewatering of the support layer, for instance. More precisely, it is possible to dewater the two partial layers faster than one single support layer having a thickness which is the sum of the thicknesses of the two partial layers .
In this connection, the expression "material-homogeneous" means that the support layer formed from two partial layers made from the same stock has the structure of a support layer formed by a single thick layer, so that it is not possible to distinguish the layers from each other. In other words, the support layer formed by the two partial layers does not comprise a boundary between the partial layers . In order to achieve a higher production rate of board, it is advantageous that further layers are simultaneously formed on the partial layers during forming the same. For this purpose, the first forming section may be adapted to simultaneously form a first covering layer on one side of the first partial layer of the support layer and the second forming section may be adapted to simultaneously form a second covering layer on one side of the second partial layer of the support layer. In case the partial layers are provided with further layers in the above manner, the joining section has to be adapted to join the first partial layer and the second partial layer at the sides of the partial layers both free of covering layer together, in order to achieve a material-homogenous support layer. Advantageously, the first forming section comprises a two- layer headbox and a hybrid former.
Furthermore, the second forming section may comprise a two- layer headbox and a hybrid former. However, other suitable arrangements are also possible for forming two material layers upon each other.
In order to form the homogeneous support layer, the joining section may be adapted to couch the first partial layer and the second partial layer together so as to form the
homogeneous support layer. However, it is also possible to join the layers together in other suitable ways.
A particular advantageous formation of the device may comprise a further forming section having a one-layer headbox and a fourdrinier former or having a further two- layer headbox and a hybrid former, and may be adapted to form a further covering layer on at least one of the first covering layer and the second covering layer.
The method for manufacturing a web consisting of multiple layers, wherein one of the layers is a support layer being heavier than any other layer of the web, comprises the steps of forming a first partial layer of the support layer, forming a second partial layer of the support layer, and joining the first partial layer and the second partial layer both being made from stock having identical
composition together, so as to form a material-homogeneous support layer.
During forming the first partial layer of the support layer, a first covering layer may be simultaneously
provided on one side of the first partial layer of the support layer, and during forming the second partial layer of the support layer, a second covering layer may be simultaneously provided on one side of the second partial layer of the support layer. Furthermore, during joining the first partial layer and the second partial layer together, the first partial layer and the second partial layer may be joined together at the sides of the partial layers free of covering layer.
Advantageously, the first partial layer and the second partial layer are joined together by couching.
Moreover, the method may further comprise the step of forming a further covering layer on at least one of the first covering layer and the second covering layer. Other features and advantages of the invention will become obvious from the following description of a preferred embodiment of the invention which is described with
reference to the appended drawings, in which:
Fig. 1 shows a cross section of a multilayerboard
manufactured with a device and a method according to a first embodiment of the invention; Fig. 2 shows a non-limiting example of the device for manufacturing the multilayerboard shown in Fig. 1 ;
Fig. 3 shows a cross section of a multilayerboard
manufactured with a device and a method according to a second embodiment of the invention;
Fig. 4 shows a non-limiting example of the device for manufacturing the multilayerboard shown in Fig. 3; Fig. 5 shows a cross section of a multilayerboard
manufactured with a device and a method according to a third embodiment of the invention;
Fig. 6 shows a non-limiting example of the device for manufacturing the multilayerboard shown in Fig. 5;
Fig. 7 shows a cross section of a multilayerboard according to prior art; and Fig. 8 shows a device for manufacturing the multilayerboard shown in Fig . 7.
A first preferred embodiment of the invention is described in view of Fig. 1. Fig. 1 shows a cross section of a multilayerboard
comprising four layers manufactured with a device and method according to the invention. Just like the
multilayerboard described above and shown in Fig. 7, the multilayerboard manufactured by the device and method according to the invention comprises a middle ply 1, an undertop ply 2, a top ply 3 and a back ply 4, wherein the undertop ply 2 and the back ply 4 are provided on the middle ply 1 on opposite sides of the middle ply 1 so that the middle ply 1 is sandwiched by the undertop ply 2 and the back ply 4. The top ply 3 is provided on the undertop ply 2 on the side opposite to the side facing the middle ply 1. Furthermore, onto the sides of the top ply 3 and the back ply 4 being free of a covering layer, a coating 5, 6 is applied.
Here, the structure of the multilayerboard manufactured with the device and method according to the invention does not differ from the multilayerboard in the prior art.
Furthermore, as is the case in the multilayerboard
according to prior art, the middle ply 1 of the
multilayerboard manufactured with the device and method according to the invention is thicker and heavier than any other ply of the multilayerboard.
According to the invention, the multilayerboard is
manufactured by a device comprising three web-forming sections. More precisely, the four layers of the
multilayerboard are formed by use of three web-forming sections. The device according to the invention comprises a first forming section Fl, a second forming section F2 and a third forming section F3. A non-limiting example of such a device is shown in Fig. 2. Each of the forming sections of the device is adapted to form a specific portion of the multilayerboard, as can be gathered from Fig. 1. In detail, forming section Fl forms a first portion 7 of the board, forming section F2 forms a second portion 8 of the board and forming section F3 forms a third portion 9 of the board, as is shown in Fig. 1.
In the preferred embodiment, the first portion 7 of the multilayerboard consists of the back ply 4 and of a part of the middle ply 1, the second portion 8 of the
multilayerboard consists of the undertop ply 2 and of another part of the middle ply 1 and the third portion 9 consists of the top ply 3. All parts of the middle ply 1 are made from the same stock. In other words, the forming sections are structured such that five layers are formed by means of the three forming sections Fl, F2 and F3, wherein two of the five layers - which are referred to as first partial layer pi and second partial layer p2 in the
following - are made from the same stock and are formed simultaneously with a further layer, i.e. the back ply 4 and the undertop ply 2, respectively.
In order to manufacture the multilayerboard in the above- described way, the first forming section Fl and the second forming section F2 each comprise a two-layer headbox and a hybrid former. The two-layer headbox combines two stock flows into one jet leaving the headbox lip. The hybrid former consists of a fourdrinier section and a twin-wire zone, wherein the fourdrinier section precedes the twin- wire zone.
The fourdrinier section and the twin-wire zone are
structured in accordance with the weight of the web to be formed in order to provide a sufficient dewatering of the web. In the embodiment of the invention, the second portion 8 of the multilayerboard shown in Fig. 1 is heavier than the first portion 7 of the multilayerboard. Therefore, the fourdrinier section of the forming section F2 is longer than the fourdrinier section of the forming section Fl . However, both fourdrinier sections of the forming sections Fl and F2 can have equivalent lengths .
The forming section Fl is adapted to simultaneously form the back ply 4 and the first partial layer pi of the middle ply 1 and the forming section F2 is adapted to
simultaneously form the undertop ply 2 and the second partial layer p2 of the middle ply 1. More precisely, when simultaneously forming the back ply 4 and the first partial layer pi, the first partial layer 1 is formed on the back ply 4 so that the back ply is sandwiched by a wire of the fourdrinier section of the forming section Fl and the first partial layer 1. Similarly, the jet of stock leaving the headbox of the forming section F2 is structured such that the undertop ply 2 is sandwiched by a wire of the
fourdrinier section of the forming section F2 and the second partial layer p2. Accordingly, in the fourdrinier section, the first partial layer pi and the second partial layer 2 have a side free of a covering layer and not in contact with the wire.
In order to join the two partial layers pi and p2 formed in the above manner, the device further comprises a first joining section Jl adapted to couch the first partial layer pi and the second partial layer p2 together so as to form a material homogeneous middle ply 1. That is, after passing the first joining section Jl, a middle ply 1 is formed which - in its characteristics - does not differ from a ply not being formed from two separately formed partial layers as shown in the prior art. The web leaving the first joining section Jl consists of three layers and is guided to the second joining section J2 in which the top ply 3 is provided on the undertop ply 2 of the web. More precisely, the web consisting of middle ply 1, undertop ply 2 and back ply 4 and the top ply 3 are couched together at the second joining section J2.
After that, in the first embodiment, coatings 5 and 6 are provided on the top ply 3 and the back ply 4, respectively.
In Fig. 3 a cross section of a multilayerboard is shown being manufactured with a device and a method according to a second embodiment of the invention. The structure of the multilayerboard shown in Fig. 3 differs from the structure of the multilayerboard shown in Fig. 1 only in that the undertop ply 2 is omitted. That is, the multilayerboard only consists of two portions, namely the first portion 7 consisting of the back ply 3 and of a part of the middle ply 1 and the second portion 8 consisting of the undertop ply 2 and of the other part of the middle ply 1. A device for manufacturing the multilayerboard of Fig. 3 is shown in Fig. 4 and differs from the device shown in Fig. 2 in that the third forming section F3 and the second joining section J2 have been omitted. In other words, the forming sections are structured such that four layers are formed by means of the two forming sections Fl and F2, wherein two of the four layers - the first partial layer pi and the second partial layer p2 - are made from the same stock and are formed simultaneously with a further layer, i.e. the back ply 4 and the top ply 3, respectively.
A cross section of a multilayerboard being manufactured with a device and a method according to a third embodiment of the invention is shown in Fig. 5. The structure of the multilayerboard shown in Fig. 5 differs from the structure of the multilayerboard shown in Fig. 3 in that an
additional back ply 7 is provided between the back ply 4 and the coating 6. The corresponding device for
manufacturing the multilayerboard of Fig. 5 is shown in Fig. 6. In addition to the construction shown in Fig. 4, the device in Fig. 6 comprises a further fourdrinier former F4 and a third joining section J3 in order to form the additional back ply 7, i.e. a fourth portion 10 of the board .
As is obvious from the above description, the essence of the invention is to form the heaviest or thickest layer - the middle layer in the preferred embodiment - by joining the two partial layers pi and p2 together, such that they form one material-homogenous layer, i.e. a single layer which does not comprise a boundary between the partial layers after they have been joined. This heaviest layer is not necessarily a middle layer but may also be one layer of a two layer structure. By forming the heaviest layer in such a manner, it is possible to achieve a higher
production rate since dewatering of thinner layers can be performed faster.
However, it is, however, to be noted that the preceding description of the present invention is merely exemplary and is not intended to limit its scope in any way. Various details of the present invention may vary within the scope of the invention as defined in the claims and may differ from the exemplary details described above in accordance with the knowledge of a person skilled in the art.

Claims

1. A device for manufacturing a web consisting of at least three layers, wherein one of the layers is a support layer being heavier than any other layer of the web, the device comprising :
a first forming section adapted to form a first partial layer of the support layer,
a second forming section adapted to form a second partial layer of the support layer, and
a joining section for joining the first partial layer and the second partial layer both being made from stock having identical composition together, so as to form a material-homogeneous support layer.
2. A device according to claim 1, wherein
the first forming section is further adapted to simultaneously form a first covering layer on one side of the first partial layer of the support layer,
the second forming section is further adapted to simultaneously form a second covering layer on one side of the second partial layer of the support layer, and
the joining section is adapted to join the first partial layer and the second partial layer at the sides of the partial layers free of covering layer.
3. A device according to claim 2, wherein the first forming section comprises a two-layer headbox and a hybrid former.
4. A device according to claim 2 or 3, wherein the second forming section comprises a two-layer headbox and a hybrid former .
5. A device according to one of claims 1 to 4, wherein the joining section is adapted to couch the first partial layer and the second partial layer together so as to form the homogeneous support layer.
6. A device according to one of the preceding claims, further comprising a further forming section having a one- layer headbox and fourdrinier former or having a further two-layer headbox and hybrid former and being adapted to form a further covering layer on at least one of the first covering layer and the second covering layer.
7. A method for manufacturing a web consisting of multiple layers, wherein one of the layers is a support layer being heavier than any other layer of the web, comprising the steps :
forming a first partial layer of the support layer, forming a second partial layer of the support layer, and
joining the first partial layer and the second partial layer both being made from stock having identical
composition together, so as to form a material-homogeneous support layer.
8. A method according to claim 7, wherein
during forming the first partial layer of the support layer, a first covering layer is simultaneously provided on one side of the first partial layer of the support layer, during forming the second partial layer of the support layer, a second covering layer is simultaneously provided on one side of the second partial layer of the support layer, and
during joining the first partial layer and the second partial layer together, the first partial layer and the second partial layer are joined at the sides of the partial layers free of covering layer.
9. A method according to claim 7 or 8, wherein the first partial layer and the second partial layer are joined by couching .
10. A method according to claim 7 to 9, further comprising the step of forming a further covering layer on at least one of the first covering layer and the second covering layer .
PCT/EP2010/064658 2010-10-01 2010-10-01 Device and method for manufacturing a web consisting of multiple layers WO2012041392A1 (en)

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WO2015185295A1 (en) * 2014-06-06 2015-12-10 Voith Patent Gmbh Device for producing a fibrous web
WO2019154540A1 (en) 2018-02-09 2019-08-15 Voith Patent Gmbh Method and device for producing a multilayer fibrous web
WO2019219299A1 (en) 2018-05-18 2019-11-21 Voith Patent Gmbh Method and device for producing a fibrous web
CN112585317A (en) * 2018-08-30 2021-03-30 福伊特专利有限公司 Method and machine for producing a multi-layer fibrous web
EP4077803A4 (en) * 2019-12-19 2024-01-10 Stora Enso Oyj A light weight linerboard for corrugated board

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WO1995016070A1 (en) * 1993-12-08 1995-06-15 Beloit Technologies, Inc. Machine and method for forming multi-ply linerboard from two sheets
WO2001044569A1 (en) * 1999-12-15 2001-06-21 Metso Paper, Inc. Arrangement and method for forming a multilayered paper or paperboard web

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WO1995016070A1 (en) * 1993-12-08 1995-06-15 Beloit Technologies, Inc. Machine and method for forming multi-ply linerboard from two sheets
WO2001044569A1 (en) * 1999-12-15 2001-06-21 Metso Paper, Inc. Arrangement and method for forming a multilayered paper or paperboard web

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015185295A1 (en) * 2014-06-06 2015-12-10 Voith Patent Gmbh Device for producing a fibrous web
CN106414844A (en) * 2014-06-06 2017-02-15 福伊特专利有限公司 Device for producing a fibrous web
WO2019154540A1 (en) 2018-02-09 2019-08-15 Voith Patent Gmbh Method and device for producing a multilayer fibrous web
WO2019219299A1 (en) 2018-05-18 2019-11-21 Voith Patent Gmbh Method and device for producing a fibrous web
CN112585317A (en) * 2018-08-30 2021-03-30 福伊特专利有限公司 Method and machine for producing a multi-layer fibrous web
CN112585317B (en) * 2018-08-30 2023-06-16 福伊特专利有限公司 Method and machine for producing a multi-layer fibrous web
EP4077803A4 (en) * 2019-12-19 2024-01-10 Stora Enso Oyj A light weight linerboard for corrugated board

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