Arrangement in connection with the press and dryer section of a web forming machine

Abstract

An arrangement in connection with the press and dryer section of a web-forming machine includes first and second devices for transporting the web. The second device includes a dryer wire and a roll arranged to support it. In the arrangement there is an open gap between the first and second devices, across which the web is arranged to be transferred, so that the web and the dryer wire form a closing throat. The arrangement further includes a deflector before the open gap in the direction of travel of the dryer wire, which is arranged close to the dryer wire, in order to restrict the air layer travelling with the dryer wire, and thus to prevent the formation of an excess pressure in the closing throat.

1 . An arrangement in connection with the press and dryer section of a web-forming machine, which arrangement includes 
 first means in the press section for transporting the web manufactured on a web-forming machine,    second means in the dryer section for the onward transportation of the web manufactured on a web-forming machine, which second means include a dryer wire and a roll arranged to support it, inside which a vacuum is arranged,    in which arrangement there is an open gap between the first and second means, across which the web is arranged to be transferred from the first means to the dryer wire in the vacuum area of the roll, in which the web and the dryer wire form a closing throat, and the arrangement further includes deflector means on the side of loop formed from the dryer wire opposite to the roll and before the open gap in the direction of travel of the dryer wire, which are arranged close to the dryer wire, in order to restrict the air layer travelling with the dryer wire, and thus to prevent the formation of an excess pressure in the said closing throat, and the arrangement further includes runnability components arranged in connection with the roll inside the loop formed from the dryer wire, which are arranged to restrict the air layer travelling with the inner surface of the dryer wire and thus to prevent the formation of an excess pressure in the closing throat formed by the dryer wire and the roll, characterized in that the distance of the deflector means from the dryer wire is 1-12 mm, and the runnability components include at least one blow box.    
   
   
       2 . An arrangement according to  claim 1 , characterized in that the distance of the blow box from the part of the dryer wire on the side of the deflector means is at most 50 mm.  
   
   
       3 . An arrangement according to  claim 1 , characterized in that the distance of the deflector means from the point of contact of the roll and the dryer wire is less than 3000 mm.  
   
   
       4 . An arrangement according to  claim 1 , characterized in that the deflector means are arranged to be active or passive.  
   
   
       5 . An arrangement according to  claim 4 , characterized in that the active deflector means are formed of elements arranged to move or rotate, or of airflow devices.  
   
   
       6 . An arrangement according to  claim 4 , characterized in that the passive deflector means are formed of an air baffle or a doctor.  
   
   
       7 . An arrangement according to  claim 4 , characterized in that the distance of the active deflector means from the dryer wire is 3-12 mm.  
   
   
       8 . An arrangement according to  claim 4 , characterized in that the distance of the passive deflector means from the dryer wire is 1-6 mm.  
   
   
       9 . An arrangement according to  claim 1 , characterized in that in the blow box there is at least one blast, both before the roll and after the roll.  
   
   
       10 . An arrangement according to  claim 1 , characterized in that vacuum devices are arranged in connection with the roll, in order to create a vacuum over at least part of the distance of the area of the perforated jacket belonging to the roll.