EP0939842B1 - Caisse de tete multicouche destinee a une machine de fabrication de papier - Google Patents

Caisse de tete multicouche destinee a une machine de fabrication de papier Download PDF

Info

Publication number
EP0939842B1
EP0939842B1 EP97927534A EP97927534A EP0939842B1 EP 0939842 B1 EP0939842 B1 EP 0939842B1 EP 97927534 A EP97927534 A EP 97927534A EP 97927534 A EP97927534 A EP 97927534A EP 0939842 B1 EP0939842 B1 EP 0939842B1
Authority
EP
European Patent Office
Prior art keywords
upstream
downstream
stock
slice chamber
section
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
EP97927534A
Other languages
German (de)
English (en)
Other versions
EP0939842A1 (fr
EP0939842B2 (fr
Inventor
N. Ulf A. Haraldsson
Anders T. Linden
Ingvar B. E. Klerelid
Louise M. TÖRNEFALK-SVANQVIST
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Valmet AB
Original Assignee
Metso Paper Karlstad AB
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
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=20403001&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP0939842(B1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Metso Paper Karlstad AB filed Critical Metso Paper Karlstad AB
Publication of EP0939842A1 publication Critical patent/EP0939842A1/fr
Publication of EP0939842B1 publication Critical patent/EP0939842B1/fr
Application granted granted Critical
Publication of EP0939842B2 publication Critical patent/EP0939842B2/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/02—Head boxes of Fourdrinier machines
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/02—Head boxes of Fourdrinier machines
    • D21F1/028—Details of the nozzle section

Definitions

  • the present invention relates to a multilayer headbox for ejecting stock into a forming section of a papermaking machine for forming a fibrous web.
  • stock is ejected from a slice chamber of a headbox into a forming section of a papermaking machine.
  • the forming section may comprise a single forming fabric, a forming fabric in combination with a felt, or a pair of forming fabrics.
  • water drains from the stock through a forming fabric so that a fibrous web is formed.
  • layer purity should be understood as the degree to which the separate layers of the fibrous web are able to retain their respective composition, i. e. the degree to which mixing of the layers is avoided, while coverage should be understood as the degree to which each layer of the fibrous web has a uniform basis weight in the cross machine direction.
  • the formed web has a poor coverage, this will have an adverse effect on the uniformity of the layer purity, which will render the operation of the papermaking machine more difficult since a uniform layer purity is required during subsequent phases of the papermaking process, e. g. during creping when the creping doctor will be adjusted in accordance with the surface properties of the fibrous web on the side adhering to the drying cylinder.
  • a uniform layer purity is required during subsequent phases of the papermaking process, e. g. during creping when the creping doctor will be adjusted in accordance with the surface properties of the fibrous web on the side adhering to the drying cylinder.
  • chemicals are added to the process in order to facilitate creping and the quantity and composition of the chemicals will depend on the surface qualities of the fibrous web.
  • a web of non-uniform layer purity will render impossible an optimization of the papermaking process since adjustment of the creping doctor and the adding of chemicals will depend on the surface qualities of the fibrous web.
  • the paper web should have a uniform strength across the web (i. e. in the cross machine direction) and a web having poor coverage will not be of uniform strength across the web. Therefore, there is a need for a multilayer headbox which is able to produce a multilayered web which has a good and uniform layer purity and a good coverage and which is also free of flocculations and has a uniform basis weight.
  • the object of the invention is to provide a multilayer headbox, which is able to produce a layered fibrous web that has a good and uniform layer purity and that is free of flocculations and has a uniform basis weight.
  • the object of the invention is attained by the present invention which is directed to a multilayer headbox for a papermaking machine.
  • the headbox comprises a slice chamber which has an upstream inlet where stock is intended to enter the slice chamber and a downstream outlet through which stock is intended to pass from the slice chamber to a subsequent forming section of the papermaking machine.
  • the slice chamber has an intended straight main direction of flow of the stock from the inlet of the slice chamber to the outlet of the slice chamber.
  • the slice chamber has a top wall, a bottom wall and two side walls.
  • the top and bottom walls converge in the straight main direction of flow of the stock through the slice chamber.
  • the headbox further comprises a tube bank located upstream of the slice chamber in the direction of flow of the stock.
  • the tube bank comprises a plurality of straight tubes.
  • the tubes of the tube banks are arranged in vertically spaced tube bank sections such that each tube bank section in the tube bank is arranged to feed stock exclusively intended for one layer of the fibrous web to be formed.
  • the tubes are arranged in vertically spaced rows, the rows extending in a cross machine direction.
  • the tube bank can thus be described as comprising a plurality of straight tubes where the tubes are arranged in separate vertically spaced rows.
  • Each tube has an upstream inlet end and a downstream outlet end from which stock is intended to pass into the inlet of the slice chamber such that the tube bank with its tubes forms a passage through which stock is intended to pass from the upstream inlet end of the tubes to the inlet of the slice chamber.
  • the passage has a straight main direction of flow of the stock which coincides with the intended straight main direction of flow of the stock in the slice chamber so that all the way from the upstream inlet end of the tubes to the downstream outlet of the slice chamber, the stock will flow in one and the same straight main direction of flow.
  • the headbox comprises at least one, but possibly two or three, machine-wide separator vane or vanes in the slice chamber.
  • the separator vane (or vanes) subdivides the slice chamber such that a multilayered fibrous web may be formed.
  • the separator vane (or vanes) has an upstream end and a downstream end and extend in the intended direction of flow of the stock and has a thickness in the vertical dimension.
  • elongate ledges are provided that extend in a cross machine direction and connect the tube bank sections to each other.
  • the upstream end of the separator vane (or of each separator vane) is fastened to one of the elongate ledges interposed between the vertically spaced tube bank sections in the tube bank.
  • Such a headbox is known from WO-A-95/08023 and forms the preamble of claim 1.
  • the headbox further comprises, in the slice chamber, a plurality of machine-wide turbulence generating elements extending in the direction of flow of the stock.
  • Each turbulence generating element has an upstream end and a downstream end.
  • the upstream end of each turbulence generating element is interposed between the vertically spaced rows of tubes in a tube bank section and fixed between the rows.
  • the turbulence generating elements can be realized in the form of vanes with uneven, i. e. rough surface but the inventors have found that also vanes with a smooth surface will have a turbulence generating effect which is sufficient for the purpose of the invention.
  • the separator vanes are made to have a certain minimum stiffness in the cross machine direction for at least 7/10 of the length of the separator vane.
  • the stiffness of the separator vane is chosen to be on average at least 36 Nm and on at least 7/10 of the length of each separator vane, at least 7 Nm.
  • the separator vane (or vanes) should have an average stiffness which is at least 180 times higher than the stiffness of a 1 mm thick reference sheet or reference plate of a material having a modulus of elasticity of about 2100 MPa and that for at least 7/10 of the length of the vane (or vanes), the stiffness should be at least 35 times higher than for the reference sheet or reference plate.
  • the separator vane (or separator vanes) is a homogenous element made of glass fiber reinforced epoxy resin and is tapered all the way from its upstream end to its downstream end such that its thickness decreases continuously from its upstream end to its downstream end.
  • the separator vane (or vanes) is divided into an upstream section of constant thickness in the vertical dimension and a downstream section which is tapered such that its thickness decreases in the direction of flow of the stock.
  • the upstream section will have an upstream end which is the same as the upstream end of the separator vane and a downstream end to which the downstream section is fixed.
  • the downstream section will have an upstream end fixed to the upstream section of the separator vane and a downstream end which is the same as the downstream end of the separator vane.
  • the downstream section has a thickness in the vertical dimension which is less than the thickness in the vertical dimension of the upstream section.
  • the upstream section might be of steel while the downstream section is preferably of glass fiber reinforced epoxy resin.
  • the separator vane(s) is a homogenous element tapered all the way from its upstream end to its downstream end
  • the separator vane(s) has a surface smoothness, or R a value, which is smaller than or equal to 0.4 ⁇ m.
  • the tapered downstream section has surface smoothness, or R a value, which is smaller than or equal to 0.4 ⁇ m.
  • the thickness in the vertical dimension of the separator vane is less than 0.7 mm at the downstream end of the separator vane(s).
  • the thickness in the vertical dimension should be about 0.5 mm.
  • the thickness in the cross machine direction will of course be subject to a degree of variation. The inventors have found that the thickness at the downstream end should not vary more than 0.05 mm. When the thickness of the separator vane is chosen to be 0.5 mm, this will therefore result in a separator vane which, at its downstream end, has a thickness of 0.5 mm ⁇ 0.05 mm or 0.45 mm - 0.55 mm.
  • Providing a separator vane, or separator vanes, having a surface smoothness which is, at least at a downstream end of the separator vane(s), smaller than 0.4 ⁇ m and having a thickness at its downstream end which is less than 0.7 mm contributes to the achievement of a good layer purity.
  • layer purity it can be desirable to make the downstream end of the separator vane (or vanes) even thinner.
  • the inventors have found that when the tip of a vane (the downstream end of the vane) is thinner than 0.5 mm, this makes the tip to weak and to likely to be broken by fatigue. Therefore, the inventors have found that a thickness of about 0.5 mm is preferable. In order to achieve that the layer purity will also be uniform, it is necessary that the formed web will also have a good coverage.
  • the inventors have found that when the headbox is formed as a straight flow headbox, i. e. when the stock flows in one and the same main direction of flow all the way from the inlet end of the tubes in the tube bank to the outlet of the slice chamber, this will have an advantageous effect on the coverage of the subsequently formed fibrous web and that this advantageous effect can be reinforced by providing turbulence generating elements in the slice chamber.
  • Headboxes are known, e g. from U. S. Patent No. 4,941,950 (Sanford), where the stock is forced to change its direction of flow when it enters the slice chamber.
  • the inventors of the present invention have recognized that such a design will have a disadvantageous effect on the coverage of the fibrous web and therefore, the inventors have designed the headbox of the present invention as a straight flow headbox such that the stock will not change its direction of flow as it enters the slice chamber.
  • the separator vane, or separator vanes should be stiff in the cross machine direction.
  • the inventors have found that one important cause for poor coverage is insufficient stiffness of the separator vane(s) in the cross machine direction. If the stiffness of the vane(s) in the cross machine direction is insufficient, this may cause flexing of the vane(s) such that, in the cross machine direction, the layers of the subsequently formed web will not have a uniform basis weight in the cross machine direction, i. e. the coverage will be poor. It is also desirable that the stiffness in the machine direction is high if a fibrous web which is uniform in the machine direction is to be obtained.
  • the separator vanes employed in the present invention are of such a design that their thickness decreases towards the tip of the vanes, i. e. the thickness of a vane is less at the downstream end of the vane than at the upstream end of the vane. For this reason, the stiffness of the vane is not uniform. Instead, the stiffness of each vane decreases towards the downstream end of the vane. Therefore, the stiffness of a separator vane according to the present invention has to be calculated at different locations of the vane.
  • the Poisson ratio will normally be about 0.3 while for glass fiber reinforced resin, the Poisson ratio can be given as about 0.15. The stiffness is thus proportional to the product of the modulus of elasticity and the plate thickness.
  • the material or materials used for the separator vane is isotropic in the sense that it has the same properties in both the machine direction and the cross machine direction (but not necessarily in the vertical dimension). Therefore, the stiffness of a separator vane, such as stiffness is defined in the context of this application, will be the same in both the machine direction and the cross machine direction.
  • One way of increasing the stiffness is to increase the thickness of the vane(s). However, at the downstream end of the vane(s), the thickness of the vane(s) must be small, preferably less than 0.7 mm and preferably about 0.5 mm, in order to obtain good layer purity.
  • the material or materials used for the separator vane (or vanes) is isotropic in the sense that it has the same properties in both the machine direction and the cross machine direction. For this reason, the stiffness at any given location along the length of a separator vane, as stiffness is defined in the context of this application, will be the same in both the machine direction and the cross machine direction.
  • the tests carried out by the inventors showed that when the 1 mm thick reference sheet was used as a separator vane, the formed fibrous web had unsatisfactory coverage.
  • the separator vane(s) has a stiffness in the cross machine direction which, for at least 7/10 (70%) of its length is at least 35 times greater than the stiffness of a 1 mm thick reference sheet of a polycarbonate material having a modulus of elasticity of about 2100 MPa.
  • the vanes that where found to give satisfactory results with regard to the coverage of the formed fibrous web had an average stiffness which was at least 180 times higher than the stiffness of the reference sheet.
  • average stiffness should here be understood as the stiffness value which is obtained by choosing at least 11 points on the separator vane evenly spaced from each other in the machine direction, adding the stiffness values of the different points and dividing the result by the number of points.
  • the expression "for at least 7/10 of its length....35 times greater than a 1 mm thick reference sheet of a material having a modulus of elasticity of about 2100 MPa” should here be understood as meaning that the stiffness at the upstream end of the separator vane(s) is much higher than a 1 mm thick sheet (or plate) of a polycarbonate material having a modulus of elasticity of about 2100 MPa and that the stiffness gradually decreases towards the downstream end of the separator vane(s) but that for at least 7/10 (70%) of its length, the vane(s) has a stiffness at least 35 times greater than a 1 mm thick reference sheet (or reference plate) of a polycarbonate material having a modulus of elasticity of about 2100 MPa so that no more
  • a separator vane (or separator vanes) which is tapered such that its thickness decreases linearly from its upstream end to its downstream end.
  • the material used for this vane is an isotropic glass fiber reinforced epoxy resin having a modulus of elasticity of 25,000 MPa.
  • this vane may have a thickness of 3.8 mm. The thickness gradually decreases towards the tip (the downstream end of the vane) where the thickness will be about 0.5 mm.
  • the Poisson ratio is 0.15.
  • the stiffness gradually decreases but for 7/10 (70%) of the length of the separator vane, the stiffness is at least 7 Nm and thus at least 35 times higher than the stiffness of the 1 mm thick reference sheet.
  • the average stiffness in this case will be about 36 Nm and thus at least 180 times higher than the stiffness of the 1 mm thick reference sheet.
  • the upstream section will have a substantially constant stiffness all the way from the upstream end of the vane(s) to the point where the downstream section of the separator vane(s) is fastened to the upstream section.
  • the downstream section will then have a gradually decreasing stiffness.
  • the upstream section of constant thickness may be of steel and have a modulus of elasticity of 203,000 MPa and a thickness of about 12 mm.
  • the Poisson ratio ( v ) in this case is about 0.3.
  • the length of the upstream steel section may be around 500 mm.
  • the downstream section has a linearly decreasing thickness which goes from 3.8 mm at its upstream end to about 0.5 mm at its downstream end.
  • the material chosen for the downstream section is glass fiber reinforced epoxy resin having a modulus of elasticity of 25000 MPa and the Poisson ratio ( v ) is about 0.3.
  • the length of the downstream section may be around 330 mm, giving the separator vane a total length of 830 mm.
  • the stiffness of the upstream end of the downstream section as stiffness is defined in the context of this patent application, can be calculated as being 117.2 Nm.
  • the stiffness of this separator vane will be at least 57 Nm and therefore more than 280 times stiffer than the 1 mm thick reference sheet.
  • the average stiffness will be about 20449 Nm and therefore much more than 180 times higher than the stiffness of the reference sheet.
  • the machine-wide step at the transition between the upstream section of the separator vane(s) and the downstream section of the vane(s) will also contribute to the achievement of good coverage.
  • a headbox 1 With reference to FIG. 1, a headbox 1 is shown.
  • the headbox has a slice chamber 2 which is limited by a top wall 3 and a bottom wall 4 and a pair of side walls (not shown).
  • the slice chamber has an upstream inlet 5 and a downstream outlet 6 and during operation, the stock will pass from the inlet 5 to the outlet 6 such that the slice chamber can be described as having an intended straight main direction of flow from the upstream inlet 5 to the downstream outlet 6 .
  • Upstream of the slice chamber in the intended direction of flow of the stock there is a tube bank 18.
  • the tube bank 18 comprises several sections 7, 8, 9 of tubes that are vertically spaced from each other.
  • Each tube bank section in the tube bank comprises a plurality of straight tubes 10, 11, 12, 13, 14, 15 and the tubes in each tube bank section are arranged in separate vertically spaced rows, the rows extending in a cross machine direction.
  • Each tube has an upstream inlet end 16 through which stock is intended to enter the tube and a downstream outlet end 17 through which stock is intended to pass into the slice chamber at the inlet or inlet end 5 of the slice chamber 2 .
  • the tube bank 18 with its tubes thus forms a passage through which stock is intended to pass from the upstream inlet end of the tubes to the inlet of the slice chamber 2 and into the slice chamber 2 .
  • the passage constituted by the tube bank 18 has a straight main direction of flow which coincides with the straight main direction of flow of the stock in the slice chamber or, in other words, when the stock leaves the tube bank 18 and enters the slice chamber 2 , the stock will not change its direction of flow (the flow of stock will, of course, converge but the main direction of flow will remain unchanged). The stock will thus flow in one and the same main direction of flow all the way from the upstream inlet end of the tubes in the tube bank to the downstream outlet of the nozzle chamber.
  • FIG. 3 a cross section of a 3-layered paper web is shown where the top and bottom layers may consist of short fibers while the middle layer may consist of long fibers. If the stock is instead forced to change its direction of travel as it enters the slice chamber, this will tend to result in a fibrous web of inferior coverage such that the formed fibrous web will have a cross section similar to the one indicated in FIG. 5. As can be seen in FIG. 5, the layers are well separated but each layer does not have a uniform basis weight.
  • FIG. 4 shows a cross section of a paper web where the layers are mixed together with each other such that layer purity is poor.
  • the headbox is provided with elongate ledges 19 that extend in a cross machine direction.
  • the elongate ledges 19 make possible the attachment of machine-wide separator vanes 20, 21 that subdivide the slice chamber into separate channels for the production of a multilayered fibrous web.
  • FIG. 1 two separator vanes are shown but it is to be understood that the invention could equally well be applied to a headbox having only one separator vane or possibly three separator vanes.
  • the separator vanes 20, 21 extend in the intended direction of flow of the stock and each of the machine-wide separator vanes 20, 21 has an upstream end 22 and a downstream end 23 and the upstream end of each separator vane is fastened to one of the elongate ledges interposed between the vertically spaced rows of tubes in the tube bank 18.
  • the separator vanes are given a stiffness which is, on average, at least 36 Nm and which is , on a part of the separator vane stretching from the upstream end of the separator vane up to at least 7/10 (70 %) of the length of the separator vane, has a stiffness which is at least 7 Nm.
  • the separator vanes will thereby have a stiffness which is, on average, at least 180 times greater than a 1 mm thick reference sheet or reference plate of a polycarbonate material having a modulus of elasticity of 2100 MPa and which, on a part of the separator vane stretching from the upstream end of the separator vane up to at least 7/10 of the length of the separator vane, has a stiffness in the cross machine direction which is at least 35 times greater than the stiffness of a 1 mm thick reference sheet or reference plate of a polycarbonate material having a modulus of elasticity of 2100 MPa.
  • each separator vane is made of glass fiber reinforced epoxy resin having a modulus of elasticity of about 25,000 MPa and has a thickness calculated to result in an average stiffness of the separator vane in the cross machine direction which is at least 180 times higher than the stiffness of a 1 mm thick reference sheet of a polycarbonate material having a modulus of elasticity of 2100 MPa and a stiffness which , from the upstream end of the separator vane over at least 7/10 (70%) of the length of the separator vane, is at least 35 times higher than the stiffness of a 1 mm thick reference sheet (or reference plate) of a polycarbonate material having a modulus of elasticity of 2100 MPa.
  • FIG. 6 a comparative stiffness study between a 1 mm thick reference sheet of a polycarbonate material having a modulus of elasticity of 2100 MPa and two different separator vanes in accordance with the present invention is shown.
  • curve 1 shows (as a reference) the stiffness of a 1 mm thick reference sheet (or reference plate) of a polycarbonate material having a modulus of elasticity of 2100 MPa
  • curve 2 shows the stiffness of a tapered separator vane of glass fiber reinforced epoxy resin according to the preferred embodiment of the present invention as compared to that of the 1 mm thick reference sheet.
  • the average value of the stiffness is, in this case, about 36.2 Nm and thus about 181 times higher than the reference value of the 1 mm thick reference sheet of a polycarbonate material having a modulus of elasticity of 2100 MPa and has, for 7/10 of the length of the vane, a stiffness of at least 7.1 Nm and thus 35.5 times higher than the stiffness of a 1 mm thick reference sheet of a polycarbonate material having a modulus of elasticity of 2100 MPa.
  • the separator vane has a thickness at its upstream end of approximately 3.8 mm.
  • each separator vane The thickness decreases linearly towards the downstream end of each separator vane, the length of which may be on the order of 800 - 850 mm, (the inventors envisage that 830 mm is a suitable choice of separator vane length) and at the downstream end of the vane, the thickness will be on the order of approximately 0.5 mm.
  • the inventors have found that, in order to achieve good layer purity, the thickness of the vanes should not exceed 0.7 mm at the downstream end of the separator vanes.
  • the inventors envisage that the thickness at the downstream end may be around 0.5 mm and that the variation in the thickness should be no greater than 0.05 mm.
  • the thickness is chosen to be lower than 0.7 mm in order to achieve a good layer purity.
  • a thickness of about 0.5 is preferred. With regard to the coverage, it is preferable that the thickness variation is no greater than 0.05 mm.
  • the material used for the separator vanes is isotropic in the sense that it has the same mechanical properties in both the machine direction and the cross machine direction. It is to be noted that the mechanical properties in the vertical dimension are not necessarily the same as in the machine direction and the cross machine direction. The material used is therefore not necessarily isotropic in the sense that it has the same mechanical properties in all directions.
  • each separator vane is composed of a machine-wide upstream section 31 and a machine-wide downstream section.
  • the upstream section 31 has an upstream end which is the same as the upstream end of the separator vane itself, and a downstream end 33 to which the downstream section 29 is fixed.
  • the upstream section is composed of a steel plate of constant thickness while the downstream section 29 is made of glass fiber reinforced epoxy resin.
  • the steel plate has a modulus of elasticity of 203,000 MPa and its thickness is 12 mm.
  • the stiffness of the upstream section can thus be calculated as being 32123 Nm and therefore 160615 times higher than the stiffness of the 1 mm reference sheet.
  • the downstream section has an upstream end 30 and a downstream end 23 common with the downstream end of the separator vane itself.
  • the upstream end 30 of the downstream section 29 is fixed to the downstream end 33 of an associated upstream section.
  • the downstream section has, at its upstream end, a thickness which is less than the thickness of the downstream end of the upstream section so that at the transition between the upstream section and the downstream section, there is a machine-wide step 32.
  • the machine-wide downstream section is tapered in such a way that its thickness decreases linearly in the direction of flow of the stock and is preferably made of glass fiber reinforced epoxy resin having a modulus of elasticity of 25,000 MPa.
  • the downstream section 29 has, at its upstream end, a thickness of 3.8 mm and the stiffness at the upstream end can be calculated as being about 117 Nm as stiffness is defined in the context of this patent application.
  • the thickness of the downstream section is made less than 0.7 mm at the downstream end of the downstream section.
  • the thickness at the downstream end of the downstream section may be 0.5 mm with a maximum variation of 0.05 mm such that the thickness lies in the range 0.45 mm - 0.55 mm.
  • the surface smoothness, or R a value, of the downstream section is made to be smaller than 0.4 ⁇ m.
  • curve 3 shows the stiffness of a separator vane according to the second embodiment of the invention compared to the stiffness of a 1 mm thick reference sheet (or reference plate) of a polycarbonate material having a modulus of elasticity of 2100 MPa.
  • the separator vane composed of an upstream section of constant thickness and a downstream tapered section has, during a first part of its length (the upstream section which has a constant thickness), a constant stiffness.
  • the tapered downstream section has a gradually decreasing stiffness towards its downstream end.
  • the average stiffness of this vane will be considerably higher than 180 times the stiffness of a 1 mm thick reference sheet of a polycarbonate material having a modulus of elasticity of 2100 MPa.
  • the average stiffness of this separator vane as stiffness is defined in the context of this patent application, will be 20449 Nm.
  • the stiffness will be higher than 57.1 Nm and therefore more than 280 times higher than the stiffness of the 1 mm thick reference sheet of a polycarbonate material having a modulus of elasticity of 2100 MPa which has a stiffness of 2.1 Nm.
  • the slice chamber 2 of the headbox is further provided with a plurality of machine-wide turbulence generating elements 25, 26, 27 as can be seen in FIG. 9.
  • Each turbulence generating element is located in one of the separate flow channels formed either between the top wall 3 and a separator vane 20, 21, between two separator vanes 20, 21 or between a separator vane 20, 21 and the bottom wall 4 .
  • Each of the machine-wide turbulence generating elements extends in the direction of flow of the stock and each turbulence generating element has an upstream end 34 and a downstream end 28 .
  • the upstream end 34 of each turbulence generating element 25, 26, 27 is interposed between two vertically spaced rows of tubes in the tube bank and fixed between said rows.
  • the invention achieves that a multilayered fibrous web can be produced which has a good layer purity and a good coverage which assures that the layer purity will also be uniform.
  • the fibrous web will have uniform strength properties across the web.

Landscapes

  • Paper (AREA)
  • Sheets, Magazines, And Separation Thereof (AREA)
  • Making Paper Articles (AREA)
  • De-Stacking Of Articles (AREA)

Claims (5)

  1. Caisse de tête (1) pour une machine de fabrication de papier comprenant :
    a) une chambre de règle (2) ayant un orifice d'entrée amont (5) dans laquelle il est prévu que la pâte à papier pénètre dans la chambre de règle (2) et un orifice de sortie (6) à travers lequel il est prévu que la pâte à papier passe de la chambre de règle (2) dans une section de formation suivante de la machine de fabrication de papier, la chambre de règle (2) ayant une direction principale droite d'écoulement de la pâte à papier entre l'orifice d'entrée (5) de la chambre de règle (2) et l'orifice de sortie (6) de la chambre de règle (2), la chambre de règle (2) ayant en outre une paroi supérieure (3) et une paroi inférieure (4), les parois supérieure et inférieure (3, 4) convergeant dans la direction principale droite de l'écoulement de la pâte à papier,
    b) dans la chambre de règle (2), au moins une palette de séparateur sur toute la largeur de la machine (20, 21) subdivisant la chambre de règle (2) pour la production de toiles fibreuses multicouches, ladite au moins une palette de séparateur (20, 21) s'étendant dans la direction de l'écoulement de la pâte à papier et ayant une épaisseur dans le sens vertical et une extrémité amont (22) et une extrémité aval (23), ladite au moins une palette de séparateur (20, 21) ayant, entre son extrémité amont (22) et son extrémité aval (23) une épaisseur décroissante dans le sens vertical,
       la caisse de tête multicouche étant caractérisée en ce qu'elle comprend en outre :
    c) une rampe de tubes (18) situés en amont de la chambre de règle (2) dans la direction de l'écoulement de la pâte à papier, la rampe de tubes (18) comprenant une pluralité de tubes droits (10, 11, 12, 13, 14, 15) et les tubes (10, 11, 12, 13, 14, 15) étant agencés en rangées séparées espacées verticalement (7, 8, 9), les rangées s'étendant dans la direction transversale de la machine, chaque tube ayant une extrémité d'orifice d'entrée amont (16) dans laquelle il est prévu que la pâte à papier pénètre dans le tube (10, 11, 12, 13, 14, 15) et une extrémité d'orifice de sortie aval (17) de laquelle il est prévu que la pâte à papier passe dans l'orifice d'entrée (5) de la chambre de règle (2), la rampe de tubes (18) formant un passage à travers lequel il est prévu que la pâte à papier passe de l'extrémité d'orifice d'entrée amont (16) des tubes (10, 11, 12, 13, 14, 15) à l'orifice d'entrée (5) de la chambre de règle (2), ledit passage ayant une direction principale droite d'écoulement de la pâte à papier qui coïncide avec la direction principale droite d'écoulement de la pâte à papier dans la chambre de règle (2) de telle sorte que tout le trajet entre l'extrémité d'orifice d'entrée amont (16) des tubes (10, 11, 12, 13, 14, 15) et l'orifice de sortie aval (6) de la chambre de règle (2), la pâte à papier s'écoule dans une seule et même direction principale droite d'écoulement,
    d) dans la chambre de règle (2), une pluralité d'éléments générateurs de turbulence sur toute la largeur de la machine (25, 26, 27) qui s'étendent dans la direction de l'écoulement de la pâte à papier, les éléments générateurs de turbulence (25, 26, 27) ayant une extrémité amont (34) et une extrémité aval (28), l'extrémité amont (34) de chaque élément générateur de turbulence (25, 26, 27) étant interposée entre les rangées espacées verticalement (7, 8, 9) des tubes dans la rampe de tubes (18), et étant fixée entre lesdites rangées (7, 8, 9), et
    e) ladite au moins une palette de séparateur (20, 21) ayant, au niveau de son extrémité aval (23), une épaisseur dans le sens vertical qui est inférieure à 0,7 mm et une rigidité qui, en moyenne, est égale à au moins 36 Nm et qui, sur au moins 7/10 de sa longueur a une rigidité égale à au moins 7 Nm, où la rigidité est définie comme égale à S = Eh3 /12(1-v2)
       où S est la rigidité de la palette de séparateur et E est le module d'élasticité du matériau de la palette de séparateur, h est l'épaisseur de la palette de séparateur, et v est le coefficient de Poisson pour le matériau de la palette de séparateur (20, 21).
  2. Caisse de tête multicouche (1) selon la revendication 1, dans laquelle ladite au moins une palette de séparateur sur toute la largeur de la machine (20, 21) est faite d'une résine époxy renforcée de fibres de verre et est effilée sur toute sa longueur, entre son extrémité amont (22) et son extrémité aval (23) de telle sorte que son épaisseur dans le sens vertical diminue de manière continue entre son extrémité amont (22) et son extrémité aval (23).
  3. Caisse de tête multicouche (1) selon la revendication 1, dans laquelle ladite au moins une palette de séparateur (20, 21) est divisée en une section amont (31) d'épaisseur constante dans le sens vertical et une section aval (29) qui est effilée, de telle sorte que son épaisseur diminue dans la direction de l'écoulement de la pâte à papier et dans laquelle la section amont (31) a une extrémité amont (22) et une extrémité aval (33) et la section aval (29) a une extrémité amont (30) et une extrémité aval (23) et dans laquelle l'extrémité amont (30) de la section aval (29) est fixée sur l'extrémité aval (33) de la section amont (31) et dans laquelle l'extrémité amont (30) de la section aval (29) a une épaisseur, dans le sens vertical, qui est inférieure à l'épaisseur dans le sens vertical de l'extrémité aval (30) de la section amont (31), de telle sorte que, au point où la section amont (31) est fixée à la section aval (29), se trouve un épaulement sur toute la largeur de la machine (32).
  4. Caisse de tête selon la revendication 2, dans laquelle ladite au moins une palette de séparateur sur toute la largeur de la machine (20, 21) a un lissé de surface inférieur ou égal à 0,4 µm.
  5. Caisse de tête selon la revendication 3, dans laquelle la section aval (29) a un lissé de surface inférieur ou égal à 0,4 µm.
EP97927534A 1996-06-12 1997-05-29 Caisse de tete multicouche destinee a une machine de fabrication de papier Expired - Lifetime EP0939842B2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9602347A SE506931C2 (sv) 1996-06-12 1996-06-12 Flerskiktsinloppslåda för en pappersmaskin
SE9602347 1996-06-12
PCT/SE1997/000921 WO1997047804A1 (fr) 1996-06-12 1997-05-29 Caisse de tete multicouche destinee a une machine de fabrication de papier

Publications (3)

Publication Number Publication Date
EP0939842A1 EP0939842A1 (fr) 1999-09-08
EP0939842B1 true EP0939842B1 (fr) 2002-09-04
EP0939842B2 EP0939842B2 (fr) 2006-06-28

Family

ID=20403001

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97927534A Expired - Lifetime EP0939842B2 (fr) 1996-06-12 1997-05-29 Caisse de tete multicouche destinee a une machine de fabrication de papier

Country Status (6)

Country Link
EP (1) EP0939842B2 (fr)
JP (1) JP3194967B2 (fr)
AT (1) ATE223534T1 (fr)
DE (1) DE69715236T3 (fr)
SE (1) SE506931C2 (fr)
WO (1) WO1997047804A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2098635A3 (fr) * 2008-03-07 2012-04-11 Voith Patent GmbH Dispositif de fabrication et/ou de traitement d'une bande de matière fibreuse
CN101622399B (zh) * 2007-03-01 2012-10-17 梅特索·佩珀·卡尔斯塔德公司 纸幅制造机中的流浆箱的功能部件所用的结构元件、功能部件和由其制造的流浆箱以及相关方法

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10106684A1 (de) * 2001-02-14 2002-08-29 Voith Paper Patent Gmbh Lamelle eines Stoffauflaufs einer Papier-, Karton- oder Tissuemaschine
DE10256510A1 (de) * 2002-12-04 2004-06-24 Voith Paper Patent Gmbh Stoffauflauf einer Papier- oder Kartonmaschine zur Herstellung einer Faserstoffbahn
US7785446B2 (en) 2004-10-05 2010-08-31 Toray Industries, Inc. Flow sheet for paper machine and method of manufacturing the same
EP2707542A4 (fr) * 2011-05-11 2015-04-08 Hollingsworth & Vose Co Systèmes et procédés de fabrication de bandes fibreuses

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3923593A (en) † 1971-12-03 1975-12-02 Beloit Corp Multiple ply web former with divided slice chamber
US4141788A (en) † 1978-05-02 1979-02-27 Beloit Corporation Method of and means for forming multi-ply paper webs from a single headbox
JPS5844800B2 (ja) † 1979-04-12 1983-10-05 ベロイト コ−ポレ−ション 多層ウエブを形成する方法
SE440924B (sv) † 1982-03-30 1985-08-26 Kmw Ab Inloppslada
CA1230251A (fr) † 1983-11-25 1987-12-15 Jose J. A. Rodal Regulateur flottant de debit sur caisse de tete
US4617091A (en) † 1983-11-25 1986-10-14 Beloit Corporation Headbox trailing element
US4566945A (en) † 1984-04-11 1986-01-28 Beloit Corporation Headbox trailing element
CH672515A5 (fr) † 1987-02-02 1989-11-30 Escher Wyss Gmbh
DE4225297C2 (de) † 1992-07-31 1996-11-28 Voith Sulzer Papiermasch Gmbh Stoffauflauf für eine Papiermaschine
DE4329810C2 (de) † 1993-09-03 1997-02-06 Voith Gmbh J M Geometrie des Lamellenendes eines Stoffauflaufes
SE501798C2 (sv) * 1993-09-13 1995-05-15 Valmet Karlstad Ab Flerskiktsinloppslåda
DE4440079C2 (de) † 1994-11-10 1997-10-02 Voith Sulzer Papiermasch Gmbh Mehrschichten-Stoffauflauf

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101622399B (zh) * 2007-03-01 2012-10-17 梅特索·佩珀·卡尔斯塔德公司 纸幅制造机中的流浆箱的功能部件所用的结构元件、功能部件和由其制造的流浆箱以及相关方法
EP2098635A3 (fr) * 2008-03-07 2012-04-11 Voith Patent GmbH Dispositif de fabrication et/ou de traitement d'une bande de matière fibreuse

Also Published As

Publication number Publication date
EP0939842A1 (fr) 1999-09-08
SE506931C2 (sv) 1998-03-02
DE69715236T3 (de) 2006-12-14
WO1997047804A1 (fr) 1997-12-18
JP3194967B2 (ja) 2001-08-06
SE9602347L (sv) 1997-12-13
ATE223534T1 (de) 2002-09-15
DE69715236D1 (de) 2002-10-10
EP0939842B2 (fr) 2006-06-28
DE69715236T2 (de) 2003-05-22
JPH11514050A (ja) 1999-11-30
SE9602347D0 (sv) 1996-06-12

Similar Documents

Publication Publication Date Title
US8221590B2 (en) Headbox for a machine for producing a fibrous web
US5560807A (en) Headbox additive injection system
US5549792A (en) Headbox for a paper machine
US8308909B2 (en) Sheet forming system for a machine for producing a multilayer fibrous web
US8236137B2 (en) Headbox for a machine for producing a fibrous web
US8303774B2 (en) Headbox for a machine for producing a fibrous web
EP0158584B1 (fr) Elément traînant pour caisse de tête
FI112259B (fi) Perälaatikko ja menetelmä monikerroksisen paperirainan valmistamiseksi
EP0853703B2 (fr) Procédé pour ajuster l'anisotropie d'une bande fibreuse
US6303001B1 (en) Process for improving the shrinkage cross direction profile and paper having an improved cross
US5958189A (en) Wet part of a paper making machine
EP0939842B1 (fr) Caisse de tete multicouche destinee a une machine de fabrication de papier
FI121888B (fi) Menetelmä kuiturainan ominaisuuksien optimoimiseksi
EP0147350A2 (fr) Elément traînant pour chambre de règle convergent
US6494993B1 (en) Multi-layer web formation by means of a simple basic-stock system
KR100487056B1 (ko) 제지기용다층헤드박스
CA2300280C (fr) Appareil et procede de production de turbulences de pate dans une section de mise en feuille a table plate
US20030159791A1 (en) Headbox for a paper machine, board machine, pulp machine or equivalent
FI122113B (fi) Menetelmä ja perälaatikko kuiturainan poikkisuuntaisen ominaisuusprofiilin parantamiseksi
US5888353A (en) Flatsided parabolic header for headboxes
JPS5844800B2 (ja) 多層ウエブを形成する方法
EP1161594A1 (fr) Caisse a pate pour la fabrication de papier
DE102004051255A1 (de) Blattbildungssystem
DE202004021817U1 (de) Blattbildungssystem
JPS61289196A (ja) 円網抄紙機

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19981214

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT DE FI FR GB IT SE

17Q First examination report despatched

Effective date: 20010803

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: METSO PAPER KARLSTAD AKTIEBOLAG

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

RIN1 Information on inventor provided before grant (corrected)

Inventor name: TOERNEFALK-SVANQVIST, LOUISE, M.

Inventor name: KLERELID, INGVAR, B., E.

Inventor name: LINDEN, ANDERS, T.

Inventor name: HARALDSSON, N., ULF, A.

RIN1 Information on inventor provided before grant (corrected)

Inventor name: TOERNEFALK-SVANQVIST, LOUISE, M.

Inventor name: KLERELID, INGVAR, B., E.

Inventor name: LINDEN, ANDERS, T.

Inventor name: HARALDSSON, N., ULF, A.

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT DE FI FR GB IT SE

REF Corresponds to:

Ref document number: 223534

Country of ref document: AT

Date of ref document: 20020915

Kind code of ref document: T

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

REF Corresponds to:

Ref document number: 69715236

Country of ref document: DE

Date of ref document: 20021010

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20021204

ET Fr: translation filed
PLBQ Unpublished change to opponent data

Free format text: ORIGINAL CODE: EPIDOS OPPO

PLBI Opposition filed

Free format text: ORIGINAL CODE: 0009260

PLAX Notice of opposition and request to file observation + time limit sent

Free format text: ORIGINAL CODE: EPIDOSNOBS2

26 Opposition filed

Opponent name: VOITH PAPER PATENT GMBH

Effective date: 20030604

PLAX Notice of opposition and request to file observation + time limit sent

Free format text: ORIGINAL CODE: EPIDOSNOBS2

PLBB Reply of patent proprietor to notice(s) of opposition received

Free format text: ORIGINAL CODE: EPIDOSNOBS3

PUAH Patent maintained in amended form

Free format text: ORIGINAL CODE: 0009272

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: PATENT MAINTAINED AS AMENDED

27A Patent maintained in amended form

Effective date: 20060628

AK Designated contracting states

Kind code of ref document: B2

Designated state(s): AT DE FI FR GB IT SE

REG Reference to a national code

Ref country code: FR

Ref legal event code: TP

Owner name: METSO PAPER SWEDEN AKTIEBOLAG, SE

Effective date: 20130404

REG Reference to a national code

Ref country code: GB

Ref legal event code: 732E

Free format text: REGISTERED BETWEEN 20130509 AND 20130515

REG Reference to a national code

Ref country code: DE

Ref legal event code: R082

Ref document number: 69715236

Country of ref document: DE

Representative=s name: LORENZ & KOLLEGEN PATENTANWAELTE PARTNERSCHAFT, DE

REG Reference to a national code

Ref country code: DE

Ref legal event code: R082

Ref document number: 69715236

Country of ref document: DE

Representative=s name: TBK, DE

Effective date: 20130709

Ref country code: DE

Ref legal event code: R082

Ref document number: 69715236

Country of ref document: DE

Representative=s name: TBK, DE

Effective date: 20130828

Ref country code: DE

Ref legal event code: R081

Ref document number: 69715236

Country of ref document: DE

Owner name: VALMET AB, SE

Free format text: FORMER OWNER: METSO PAPER KARLSTAD AB, KARLSTAD, SE

Effective date: 20130709

Ref country code: DE

Ref legal event code: R081

Ref document number: 69715236

Country of ref document: DE

Owner name: METSO PAPER SWEDEN AB, SE

Free format text: FORMER OWNER: METSO PAPER KARLSTAD AB, KARLSTAD, SE

Effective date: 20130709

REG Reference to a national code

Ref country code: AT

Ref legal event code: PC

Ref document number: 223534

Country of ref document: AT

Kind code of ref document: T

Owner name: METSO PAPER SWEDEN AKTIEBOLAG, SE

Effective date: 20130918

REG Reference to a national code

Ref country code: DE

Ref legal event code: R082

Ref document number: 69715236

Country of ref document: DE

Representative=s name: TBK, DE

Effective date: 20140102

Ref country code: DE

Ref legal event code: R081

Ref document number: 69715236

Country of ref document: DE

Owner name: VALMET AB, SE

Free format text: FORMER OWNER: METSO PAPER SWEDEN AB, KARLSTAD, SE

Effective date: 20140102

Ref country code: DE

Ref legal event code: R081

Ref document number: 69715236

Country of ref document: DE

Owner name: METSO PAPER SWEDEN AB, SE

Free format text: FORMER OWNER: METSO PAPER SWEDEN AB, KARLSTAD, SE

Effective date: 20140102

REG Reference to a national code

Ref country code: DE

Ref legal event code: R082

Ref document number: 69715236

Country of ref document: DE

Representative=s name: TBK, DE

REG Reference to a national code

Ref country code: FR

Ref legal event code: CD

Owner name: VALMET AKTIEBOLAG, SE

Effective date: 20140305

REG Reference to a national code

Ref country code: DE

Ref legal event code: R082

Ref document number: 69715236

Country of ref document: DE

Representative=s name: TBK, DE

Effective date: 20140317

Ref country code: DE

Ref legal event code: R081

Ref document number: 69715236

Country of ref document: DE

Owner name: VALMET AB, SE

Free format text: FORMER OWNER: METSO PAPER SWEDEN AB, SUNDSVALL, SE

Effective date: 20140317

REG Reference to a national code

Ref country code: AT

Ref legal event code: HC

Ref document number: 223534

Country of ref document: AT

Kind code of ref document: T

Owner name: VALMET AKTIEBOLAG, SE

Effective date: 20140612

REG Reference to a national code

Ref country code: FR

Ref legal event code: PLFP

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20160519

Year of fee payment: 20

Ref country code: GB

Payment date: 20160520

Year of fee payment: 20

Ref country code: FI

Payment date: 20160518

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: AT

Payment date: 20160518

Year of fee payment: 20

Ref country code: IT

Payment date: 20160524

Year of fee payment: 20

Ref country code: FR

Payment date: 20160530

Year of fee payment: 20

REG Reference to a national code

Ref country code: DE

Ref legal event code: R071

Ref document number: 69715236

Country of ref document: DE

REG Reference to a national code

Ref country code: GB

Ref legal event code: PE20

Expiry date: 20170528

REG Reference to a national code

Ref country code: AT

Ref legal event code: MK07

Ref document number: 223534

Country of ref document: AT

Kind code of ref document: T

Effective date: 20170529

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20170528