Structured forming fabric, papermaking machine and method

Abstract

A fabric for a papermaking machine that includes a machine facing side and a web facing side including pockets formed by warp and weft yarns is provided. Each pocket is defined by four sides on the web facing side, each of the four sides is formed by a knuckle of a single yarn that passes over only two consecutive yarns to define the knuckle.

1 . A papermaking machine comprising:
 a vacuum roll having an exterior surface;   a dewatering fabric having a first side and a second side, the dewatering fabric being guided over a portion of the exterior surface of the vacuum roll, the first side being in at least partial contact with the exterior surface of the vacuum roll; and   a structured fabric having a machine facing side and a web facing side including a plurality of pockets, each of said pockets is defined by four sides on the web facing side, each of the four sides formed by a knuckle of a single yarn that passes over only two other consecutive yarns to define the knuckle, wherein the dewatering fabric is positioned between the vacuum roll and the structured fabric.   
     
     
         2 . The papermaking machine according to  claim 1 , further comprising a belt press including a permeable belt having a first side, the permeable belt being guided over a portion of the vacuum roll and the first side of the permeable belt being in at least partial contact with the machine facing side of the structured fabric. 
     
     
         3 . The papermaking machine according to  claim 2 , further comprising:
 a forming roll having an exterior surface, the structured fabric being guided over a portion of the exterior surface of the forming roll and the machine facing side of the structured fabric being in at least partial contact with the exterior surface of the forming roll; and   a forming fabric having a first side and a second side, the structured fabric being positioned between the forming roll and the forming fabric.   
     
     
         4 . The papermaking machine according to  claim 3 , wherein a fibrous web is formed between the web facing side of the structured fabric and the first side of the forming fabric. 
     
     
         5 . The papermaking machine according to  claim 4 , wherein the structured fabric transfers the fibrous web to a Yankee dryer. 
     
     
         6 . A papermaking machine comprising:
 a vacuum roll having an exterior surface;   a dewatering fabric having a first side and a second side, the dewatering fabric being guided over a portion of the exterior surface of the vacuum roll, the first side being in at least partial contact with the exterior surface of the vacuum roll; and   a structured fabric having a machine facing side and a web facing side including pockets formed by warp and weft yarns, wherein each pocket is defined by four sides on the web facing side, two of the four sides each formed by a warp knuckle of a single warp yarn that passes over three consecutive weft yarns to define the warp knuckle, the other two of the four sides each formed by a weft knuckle of a single weft yarn that passes over three consecutive warp yarns to define the weft knuckle, a lower surface of each pocket being formed by first and second lower warps yarns and first and second lower weft yarns, a first warp knuckle being of the first warp yarn passed over by a first weft knuckle and the first lower warp yarn being of the second warp yarn passed over by the first weft knuckle and the second lower warp yarn being of the third warp yarn passed over the first weft knuckle, a second weft knuckle being of the first weft yarn passed over by the first warp knuckle and the second lower weft yarn being of the second weft yarn passed over by the first warp knuckle and the first lower weft yarn being of the third weft yarn passed over by the first warp knuckle, the first lower warp yarn passing over the first lower weft yarn and under the second lower weft yarn, and the second lower warp yarn passing under the first lower weft yarn and over the second lower weft yarn, and wherein the dewatering fabric is positioned between the vacuum roll and the structured fabric.   
     
     
         7 . The papermaking machine according to  claim 6 , further comprising a belt press including a permeable belt having a first side, the permeable belt being guided over a portion of the vacuum roll, wherein the first side of the permeable belt is in at least partial contact with the machine facing side of the structured fabric. 
     
     
         8 . A papermaking machine comprising:
 a Yankee dryer;   at least one structured fabric having a machine facing side and a web facing side including pockets formed by warp and weft yarns, each of the pockets defined by four sides on the web facing side, each of the four sides formed by a knuckle of a single yarn that passes over only two consecutive yarns to define the knuckle and the at least one structured fabric configured to convey a fibrous web to the Yankee dryer.   
     
     
         9 . The papermaking machine according to  claim 8 , further comprising a forming roll having an exterior surface and a forming fabric having a first side and a second side, the at least one structured fabric being guided over a portion of the exterior surface of the forming roll, the machine facing side of the structured fabric being in at least partial contact with the exterior surface of the forming roll and the at least one structured fabric being positioned between the forming roll and the forming fabric. 
     
     
         10 . The papermaking machine according to  claim 9 , further comprising a backing roll, the at least one structured fabric being a transfer fabric between the fabric roll and the Yankee dryer. 
     
     
         11 . A papermaking machine comprising:
 a Yankee dryer;   at least one structured fabric having a machine facing side and a web facing side including pockets formed by warp and weft yarns, wherein each pocket is defined by four sides on the web facing side, two of the four sides each formed by a warp knuckle of a single warp yarn that passes over three consecutive weft yarns to define the warp knuckle, the other two of the four sides each formed by a weft knuckle of a single weft yarn that passes over three consecutive warp yarns to define the weft knuckle, a lower surface of each pocket being formed by first and second lower warps yarns and first and second lower weft yarns, a first warp knuckle being of the first warp yarn passed over by a first weft knuckle and the first lower warp yarn being of the second warp yarn passed over by the first weft knuckle and the second lower warp yarn being of the third warp yarn passed over the first weft knuckle, a second weft knuckle being of the first weft yarn passed over by the first warp knuckle and the second lower weft yarn being of the second weft yarn passed over by the first warp knuckle and the first lower weft yarn being of the third weft yarn passed over by the first warp knuckle, the first lower warp yarn passing over the first lower weft yarn and under the second lower weft yarn, and the second lower warp yarn passing under the first lower weft yarn and over the second lower weft yarn, and wherein the at least one structured fabric conveys a fibrous web to the Yankee dryer.   
     
     
         12 . The papermaking machine according to  claim 11 , further comprising a forming roll having an exterior surface and a forming fabric having first and second sides, wherein the at least one structured fabric is guided over a portion of the exterior surface of the forming roll and the machine facing side of the structured fabric is in at least partial contact with the exterior surface of the forming roll, wherein the at least one structured fabric is positioned between the forming roll and the forming fabric. 
     
     
         13 . A method of pressing a fibrous material web in a papermaking machine, the method comprising the steps of:
 forming a fabric for the papermaking machine, the fabric having a machine facing side and a web facing side including pockets formed by a plurality of warp yarns and weft yarns, each of the pockets being defined by four sides on the web facing side, each of the four sides formed by a knuckle of one yarn of the plurality of warp yarns and weft yarns that passes over only two consecutive other yarns of the plurality of warp yarns and weft yarns to define the knuckle;   forming the fibrous material web; and   applying pressure to the fabric and the fibrous material web.   
     
     
         14 . The method according to  claim 13 , wherein the papermaking machine is one of a TAD system, an ATMOS™ system and an E-TAD system. 
     
     
         15 . A method of pressing a fibrous material web in a papermaking machine, the method comprising the steps of:
 forming a fabric for the papermaking machine, the fabric having a machine facing side and a web facing side including pockets formed by a plurality of warp yarns and weft yarns, wherein each pocket is defined by four sides on the web facing side, two of the four sides each formed by a warp knuckle of a single warp yarn that passes over three consecutive weft yarns to define the warp knuckle, the other two of the four sides each formed by a weft knuckle of a single weft yarn that passes over three consecutive warp yarns to define the weft knuckle, a lower surface of each pocket being formed by first and second lower warps yarns and first and second lower weft yarns, a first warp knuckle being of the first warp yarn passed over by a first weft knuckle and the first lower warp yarn being of the second warp yarn passed over by the first weft knuckle and the second lower warp yarn being of the third warp yarn passed over the first weft knuckle, a second weft knuckle being of the first weft yarn passed over by the first warp knuckle and the second lower weft yarn being of the second weft yarn passed over by the first warp knuckle and the first lower weft yarn being of the third weft yarn passed over by the first warp knuckle, the first lower warp yarn passing over the first lower weft yarn and under the second lower weft yarn, and the second lower warp yarn passing under the first lower weft yarn and over the second lower weft yarn;   forming the fibrous web; and   applying pressure to the fibrous material web and the fabric.   
     
     
         16 . The method according to  claim 15 , wherein the papermaking machine is one of a TAD system, an ATMOS™ system and an E-TAD system.