Machine for the production of tissue paper

Abstract

This invention relates to a machine for the production of a tissue paper web with a forming section in which the tissue paper web is formed from a pulp suspension on a skin and with a nip which is formed between the cylindrical surface of a drying cylinder, in particular a Yankee drying cylinder, and a mating surface and through which the tissue paper web can be conveyed together with the skin. The configuration of the machine is variable such that, depending on the quality of the tissue paper to be produced, for example its absorbency or tear resistance, the skin is either a three-dimensionally structured skin, a structured mesh, a non-structured skin, or a felt, whereby the mating surface is formed by the cylindrical surface of a press roller which includes a suction zone and in which provision is made for bores communicating with the suction zone.

1 . A machine for the production of a tissue paper web, comprising 
 a skin being one of a three-dimensionally structured skin, a structured mesh, a non-structured skin and a felt;    a drying cylinder having a cylindrical surface;    a press roller having a mating surface that is formed by a cylindrical surface of said press roller, said cylindrical surface having a plurality of bores therein; and    a forming section in which the tissue paper web is formed from a pulp suspension on said skin, between said cylindrical surface of said drying cylinder and said mating surface a nip is formed, through said nip the tissue paper web is conveyed together with said skin, a configuration of the machine being variable such that depending on said quality of the tissue paper to be produced, said quality being at least one of absorbency and tear resistance, said skin altered between said three-dimensionally structured skin, said structured mesh, said non-structured skin and said felt, said mating surface being formed by said cylindrical surface of said press roller which includes a suction zone, at least some of said plurality of bores communicating with said suction zone.    
   
   
       2 . The machine of  claim 1 , wherein said three-dimensionally structured skin is used for said production of tissue paper with higher absorbency and said non-structured skin for said production of tissue paper with lower absorbency.  
   
   
       3 . The machine of  claim 1 , further comprising a dewatering apparatus positioned between said forming section and said nip, said dewatering apparatus being operated in relation to said nip such that the tissue paper web is dewatered by said dewatering apparatus to a greater extent during operation with said structured skin and to a smaller extent during operation with said non-structured skin than by said nip.  
   
   
       4 . The machine of  claim 3 , wherein during operation with said non-structured skin the tissue paper web is not conveyed through said dewatering apparatus.  
   
   
       5 . The machine of  claim 1 , wherein said bores are arranged and constructed such that the tissue paper web downstream from said nip when operating the machine with one of said structured mesh and said felt has a dry content of 31% or more.  
   
   
       6 . The machine of  claim 1 , wherein said bores have a diameter of less than 3.8 mm.  
   
   
       7 . A machine for said production of a tissue paper web, comprising: 
 a drying cylinder having a cylindrical surface; and    a press roller having a cylindrical surface that serves as a mating surface to said drying cylinder, said cylindrical surface of said press roller having a plurality of bores therein, a nip being defined between said cylindrical surface of said drying cylinder and said mating surface, the tissue paper web being conveyed through said nip together with a permeable skin between said skin and said cylindrical surface, said press roller having a suction zone, at least some of said plurality of bores communicating with said suction zone, said bores having a diameter of less than 3.8 mm.    
   
   
       8 . The machine of  claim 7 , further comprising a forming section for forming the tissue paper web from a pulp suspension and said skin arranged such that the tissue paper web is formed in said forming section on said skin and is conveyed through said nip.  
   
   
       9 . The machine of  claim 8 , further comprising a dewatering apparatus arranged between said nip and said forming section.  
   
   
       10 . The machine of  claim 7 , wherein said bores have a diameter of one of equal to and less than 3.5 mm.  
   
   
       11 . The machine of  claim 10 , wherein said diameter of one of equal to and less than 3.0 mm.  
   
   
       12 . The machine of  claim 11 , wherein said diameter of one of equal to and less than 2.7 mm.  
   
   
       13 . The machine of  claim 7 , wherein said plurality of bores have a total open area of between 16% and 30% of said cylindrical surface area.  
   
   
       14 . The machine of  claim 13 , wherein said total open area is between 18% and 26%.  
   
   
       15 . The machine of  claim 14 , wherein said total open area is between 20% and 22%.  
   
   
       16 . The machine of  claim 7 , wherein said bores on said cylindrical surface of said press roller form a regular pattern in at least some areas.  
   
   
       17 . The machine of  claim 7 , wherein some of said plurality of bores are blind bores which are non-communicating with said suction zone, said blind bores having a diameter of one of equal to and less than 2.7 mm.  
   
   
       18 . The machine of  claim 17 , wherein said diameter is one of equal to and less than 2.4 mm.  
   
   
       19 . The machine of  claim 17 , wherein said blind bores on said cylindrical surface are arranged between said bores in at least some areas.  
   
   
       20 . The machine of  claim 7 , wherein said bores and said blind bores on said cylindrical surface of said press roller form a regular pattern in at least some areas.  
   
   
       21 . The machine of  claim 7 , wherein said bores or said bores and said blind bores on said cylindrical surface are arranged along a multiplicity of mutually parallel lines.  
   
   
       22 . The machine of  claim 7 , wherein said press roller is driven.  
   
   
       23 . The machine of  claim 7 , wherein said skin is a structured mesh.  
   
   
       24 . The machine of  claim 23 , wherein said structured mesh is a TAD mesh.  
   
   
       25 . The machine of  claim 23 , wherein a side of said structured mesh facing the tissue paper web includes depressed regions and raised regions relative to said depressed regions.  
   
   
       26 . The machine of  claim 25 , wherein the tissue paper web is formed in said depressed and raised regions of said structured mesh.  
   
   
       27 . The machine of  claim 7 , wherein a linear force generated in said nip is less than 120 kN/m.  
   
   
       28 . The machine of  claim 7 , wherein said skin is a felt.  
   
   
       29 . The machine of  claim 9 , wherein said dewatering apparatus includes: 
 a dewatering section;    a pressure apparatus; and    a pressure apparatus, said skin being one of a structured skin and a non-structured skin, the tissue paper web being conveyed along said dewatering section between said structured skin and a further permeable skin and that by way of said pressure apparatus pressure is exerted on said structured skin such that the tissue paper web is dewatered in said direction of said further permeable skin.    
   
   
       30 . The machine of  claim 29 , wherein during operation of the machine with said structured skin said dewatering apparatus contributes to the dewatering of the tissue paper and during operation of the machine with said non-structured skin said dewatering apparatus does not contribute to the dewatering of the tissue paper web.  
   
   
       31 . The machine of  claim 30 , wherein said further permeable skin is a felt.  
   
   
       32 . The machine of  claim 29 , wherein said structured skin includes depressed regions and raised regions, during pressurization in said dewatering apparatus the tissue paper web is compressed less intensively in said depressed regions than in said raised regions.  
   
   
       33 . The machine of  claim 32 , wherein the compressibility of said structured skin is less than that of said further permeable skin.  
   
   
       34 . The machine of  claim 32 , wherein a dynamic rigidity (K) is a measure for the compressibility of said structured skin, said dynamic rigidity (K) being one of equal to and more than 3000 N/mm.  
   
   
       35 . The machine of  claim 32 , wherein a dynamic rigidity (K) is a measure for the compressibility of said further permeable skin is one of equal to and less than 100,000 N/mm.  
   
   
       36 . The machine of  claim 35 , wherein said dynamic rigidity (K) is one of equal to and less than 90,000 N/mm.  
   
   
       37 . The machine of  claim 36 , wherein said dynamic rigidity (K) is one of equal to and less than 70,000 N/mm.  
   
   
       38 . The machine of  claim 29 , wherein a G modulus is a measure for an elasticity of said further permeable skin, said G modulus being one of equal to and more than 2 N/mm 2 .  
   
   
       39 . The machine of  claim 38 , wherein said G modulus is one of equal to and more than 4 N/mm 2 .  
   
   
       40 . The machine of  claim 29 , wherein a permeability of said further permeable skin is one of equal to and less than 80 cfm.  
   
   
       41 . The machine of  claim 40 , wherein said permeability is one of equal to and less than 40 cfm.  
   
   
       42 . The machine of  claim 41 , wherein said permeability is one of equal to and less than 25 cfm.  
   
   
       43 . The machine of  claim 30 , wherein a gas flow is generated by said pressure apparatus such that in order to dewater the tissue paper web first said structured skin is charged with gas, then the tissue paper web and finally said further permeable skin.  
   
   
       44 . The machine of  claim 43 , wherein said pressure apparatus includes a tensioned press belt which is arranged such that an arrangement of said structured skin, the tissue paper web and said further permeable skin can be conveyed at least in some areas along said dewatering section between said press belt and a smooth surface, whereby said press belt acts on said structured skin and said further permeable skin rests on said smooth surface.  
   
   
       45 . The machine of  claim 44 , wherein said gas flow through the tissue paper web amounts to approx. 150 m 3  per minute and meter length along said dewatering section.  
   
   
       46 . The machine of  claim 45 , wherein said press belt is under a tension of at least 30 kN/m.  
   
   
       47 . The machine of  claim 46 , wherein said tension is at least 60 kN/m.  
   
   
       48 . The machine of  claim 47 , wherein said tension is at least 80 kN/m.  
   
   
       49 . The machine of  claim 44 , wherein said press belt has an open area of at least 25% and a contact area of at least 10% of its total area facing said further permeable skin.  
   
   
       50 . The machine of  claim 44 , wherein said press belt has an open area of between 75% and 85% and a contact area of between 15% and 25% of its total area facing said further permeable skin.  
   
   
       51 . The machine of  claim 44 , wherein said press belt has an open area of between 68% and 76% and a contact area of between 24% and 32% of its total area facing said further permeable skin.  
   
   
       52 . The machine of  claim 36 , wherein said press belt has an open area of between 51% and 62% and a contact area of between 38% and 49% of its total area facing said further permeable skin.  
   
   
       53 . The machine of  claim 44 , wherein said smooth surface is formed by said circumferential surface of a roller.  
   
   
       54 . The machine of  claim 53 , wherein said pressure apparatus for generating said gas flow includes a suction zone in said roller.  
   
   
       55 . The machine of  claim 54 , wherein said suction zone has a length in said region of between 200 mm and 2500 mm.  
   
   
       56 . The machine of  claim 55 , wherein said length is between 800 mm and 1800 mm.  
   
   
       57 . The machine of  claim 56 , wherein said length is between 1200 mm and 1600 mm.  
   
   
       58 . The machine of  claim 54 , wherein a vacuum exists in said suction zone of between −0.2 bar and −0.8 bar.  
   
   
       59 . The machine of  claim 58 , wherein said vacuum is between −0.4 bar and −0.6 bar.  
   
   
       60 . The machine of  claim 54 , wherein said pressure apparatus for generating said gas flow includes a pressure hood arranged above said structured skin.  
   
   
       61 . The machine of  claim 29 , wherein the tissue paper web leaves said dewatering section with a dry content of more than 30%.