Machine for manufacturing a paper of cardboard web and press section therein

Abstract

A paper or cardboard machine press section includes sequentially arranged first, second, and third presses each having opposed first and second press members forming a press nip therebetween. A press felt is arranged in a loop and passes through the press nip of the third press. An impermeable transfer belt is arranged in a loop to receive the web from the second press and transfer it to the press felt of the third press. A wet calender defining at least one roll nip is provided between the second and third presses, and the web and the transfer belt pass through the roll nip of the wet calender. In a preferred embodiment, the roll nip of the calender is formed by a smooth press roll of the second press arranged outside the loop of the transfer belt, and a guide roll that is arranged within the loop of the transfer belt.

What is claimed is:  
     
         1 . A machine for manufacturing a continuous paper or cardboard web, comprising: 
 a forming section;    a drying section; and    a press section arranged between the forming section and the drying section, the press section including at least a first press, a second press, and a third press, each press comprising first and second opposed press members forming a press nip therebetween, the first press member of the second press comprising a smooth press roll having a smooth envelope surface for contacting the web passing through the press nip of the second press, the third press having a press felt arranged in a loop such that the press felt passes through the press nip of the third press;    wherein an impermeable transfer belt is arranged in a loop for receiving the web from the press roll of the second press and transferring the web to the third press, and the press section includes a wet calender arranged between the second press and the third press, the wet calender comprising at least a first roll nip formed between a first calender roll arranged in the loop of the transfer belt and a second calender roll arranged outside the loop of the transfer belt, the web running together with the transfer belt through the first roll nip of the wet calender.    
     
     
         2 . The machine of  claim 1 , wherein the first roll nip is operable to exert a nip pressure of about 10-100 kN per meter of web width.  
     
     
         3 . The machine of  claim 1 , wherein the smooth press roll of the second press forms the second calender roll in the first roll nip of the wet calender, the first calender roll being arranged in opposition to said smooth press roll.  
     
     
         4 . The machine of  claim 3 , wherein the first calender roll is mounted to be movable between an inactive position away from the smooth press roll and an active position in which the first calender roll forms the first roll nip with the smooth press roll.  
     
     
         5 . The machine of  claim 1 , wherein the loop of the transfer belt terminates upstream of the press nip of the third press adjacent a pick-up suction roll about which the press felt of the third press runs, and the transfer belt is arranged to carry the web adjacent the pick-up suction roll such that the pick-up suction roll transfers the web onto the press felt, and wherein a guide roll about which the transfer belt runs is arranged to guide the transfer belt away from the press felt of the third press adjacent a suction zone of said pick-up suction roll.  
     
     
         6 . The machine of  claim 1 , wherein the transfer belt is arranged to pass through the press nip of the third press.  
     
     
         7 . The machine of  claim 1 , wherein the third press is a shoe press, the second press element of the third press being a shoe press roll.  
     
     
         8 . The machine of  claim 1 , wherein the first press is one of a roll press and a shoe press.  
     
     
         9 . The machine of  claim 1 , wherein the forming section comprises a plurality of forming units for forming a plurality of layers that are couched together with each other to form a multi-layer web, one of said layers comprising a surface layer forming a top side of the multi-layer web, and wherein the wet calender is arranged to act against said surface layer of the multi-layer web.  
     
     
         10 . A press section in a machine for manufacturing a continuous paper or cardboard web, the press section comprising: 
 at least a first press, a second press, and a third press, each press comprising first and second opposed press members forming a press nip therebetween, the first press member of the second press comprising a smooth press roll having a smooth envelope surface for contacting the web passing through the press nip of the second press, the third press having a press felt arranged in a loop such that the press felt passes through the press nip of the third press;    wherein an impermeable transfer belt is arranged in a loop for receiving the web from the press roll of the second press and transferring the web to the third press, and the press section includes a wet calender arranged between the second press and the third press, the wet calender comprising at least a first roll nip formed between a first calender roll arranged in the loop of the transfer belt and a second calender roll arranged outside the loop of the transfer belt, the web running together with the transfer belt through the first roll nip of the wet calender.    
     
     
         11 . The press section of  claim 10 , wherein the first roll nip is operable to exert a nip pressure of about 10-100 kN per meter of web width.  
     
     
         12 . The press section of  claim 10 , wherein the smooth press roll of the second press forms the second calender roll in the first roll nip of the wet calender, the first calender roll being arranged in opposition to said smooth press roll.  
     
     
         13 . The press section of  claim 12 , wherein the first calender roll is mounted to be movable between an inactive position away from the smooth press roll and an active position in which the first calender roll forms the first roll nip with the smooth press roll.  
     
     
         14 . The press section of  claim 10 , wherein the loop of the transfer belt terminates upstream of the press nip of the third press adjacent a pick-up suction roll about which the press felt of the third press runs, and the transfer belt is arranged to carry the web adjacent the pick-up suction roll such that the pick-up suction roll transfers the web onto the press felt, and wherein a guide roll about which the transfer belt runs is arranged to guide the transfer belt away from the press felt of the third press adjacent a suction zone of said pick-up suction roll.  
     
     
         15 . The press section of  claim 10 , wherein the transfer belt is arranged to pass through the press nip of the third press.  
     
     
         16 . The press section of  claim 10 , wherein the third press is a shoe press, the second press element of the third press being a shoe press roll.  
     
     
         17 . The press section of  claim 10 , wherein the first press is one of a roll press and a shoe press.