Structured Forming Fabric, Papermaking Machine and Method

Abstract

A fabric for a papermaking machine is provided. The fabric includes a machine facing side and a web facing side comprising pockets formed by warp and weft yarns. Each pocket is defined by four sides of the web facing side. Two of the four sides are each formed by a warp knuckle of a single warp yarn that passes over at least three consecutive weft yarns to define the warp knuckle. The other two of the four sides are each formed by a weft knuckle of a single weft yarn that passes over two consecutive warp yarns to define the weft knuckle.

1 . A papermaking machine, comprising:
 a belt press including:
 a roll having an exterior surface; 
 a permeable belt having a first side, the permeable belt being guided over a portion of the exterior surface of the roll, and the permeable belt having a tension of at least 30 KN/m; 
   a structured fabric including:
 a machine facing side; 
 a web facing side comprising 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 at least three consecutive weft yarns to define the warp knuckle, and the other two of the four sides each formed by a weft knuckle of a single weft yarn that passes over two consecutive warp yarns to define the weft knuckle.   
     
     
         2 . The papermaking machine of  claim 1 , further comprising a third fabric, the structured fabric and the third fabric traveling between the permeable belt and the roll, the third fabric having a first and second side, the first side of the third fabric being in at least partial contact with the exterior surface of the roll, the second side of the third fabric being in at least partial contact with a first side of a fibrous web, the structured fabric having a web facing side and an opposite side, the web facing side of the structured fabric being in at least partial contact with a second side of the fibrous web, and the opposite side of the structured fabric being in at least partial contact with the first side of the permeable belt. 
     
     
         3 . The papermaking machine of  claim 2 , wherein the third fabric is a dewatering fabric. 
     
     
         4 . The papermaking machine of  claim 2 , wherein the fibrous web is formed on the structured fabric. 
     
     
         5 . The papermaking machine of  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 first and second sides, 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;   a structured fabric including:
 a machine facing side; 
 a web facing side comprising pockets formed by warp and weft yarns; 
   wherein each pocket is defined by four sides of the web facing side, two of the four sides each formed by a warp knuckle of a single warp yarn that passes over at least three consecutive weft yarns to define the warp knuckle, and the other two of the four sides each formed by a weft knuckle of a single weft yarn that passes over two consecutive warp yarns to define the weft knuckle, and wherein the dewatering fabric is positioned between the vacuum roll and the structured fabric.   
     
     
         7 . The papermaking machine of  claim 6 , wherein the machine further includes:
 a forming roll having an exterior surface;   a forming fabric having first and second sides;   wherein the 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, and the structured fabric is positioned between the forming roll and the forming fabric.   
     
     
         8 . The papermaking machine of  claim 7 , wherein a fibrous web is formed between the web facing side of the structured fabric and the first side of the forming fabric. 
     
     
         9 . The papermaking machine of  claim 8 , wherein the structured fabric transfers the fibrous web to a Yankee dryer. 
     
     
         10 . A papermaking machine, comprising:
 a Yankee dryer;   at least one structured fabric including:
 a machine facing side; 
 a web facing side comprising pockets formed by warp and weft yarns; 
   wherein each pocket is defined by four sides of the web facing side, two of the four sides each formed by a warp knuckle of a single warp yarn that passes over at least three consecutive weft yarns to define the warp knuckle, and the other two of the four sides each formed by a weft knuckle of a single weft yarn that passes over two consecutive warp yarns to define the weft knuckle, and wherein the at least one structured fabric conveys a fibrous web to the Yankee dryer.   
     
     
         11 . The papermaking machine of  claim 10 , wherein the machine further includes:
 a forming roll having an exterior surface;   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, and the at least one structured fabric is positioned between the forming roll and the forming fabric.   
     
     
         12 . The papermaking machine of  claim 10 , wherein the machine further includes a backing roll, and wherein the at least one structured fabric is a transfer fabric between the backing roll and the Yankee dryer. 
     
     
         13 . The pressing arrangement for use in a papermaking machine, comprising:
 a permeable first fabric, comprising:
 a machine facing side; 
 a web facing side comprising pockets formed by warp and weft yarns, each pocket being 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 at least three consecutive weft yarns to define the warp knuckle, and the other two of the four sides each formed by a weft knuckle of a single weft yarn that passes over two consecutive warp yarns to define the weft knuckle; 
   a permeable second fabric;   a paper web being disposed between the first fabric and the second fabric;   a pressure producing element being in contact with the first fabric;   a support surface of a supporting structure being in contact with the second fabric;   a differential pressure arrangement providing a differential pressure between the first fabric and the support surface, the differential pressure acting on at least one of the first fabric, the paper web, and the second fabric, the paper web being subjected to mechanical pressure and experiencing a hydraulic pressure so as to cause water to be drained from the paper web, the pressure arrangement being arranged to allow air to flow in a direction through the first fabric, the paper web, and the second fabric.   
     
     
         14 . The pressing arrangement of  claim 13 , wherein the second fabric includes at least one of a felt and a batt layer.