Method for calendering a paper or cardboard web

A method for calendering a paper or cardboard web in a calendering zone having a length wherein the desired smoothness of at least one surface of the web is achieved by passing the web through a single calendering zone and controlling the length of the calendering zone, comprising the steps of:

• providing a first set of parallel calendering surfaces which form a predetermined precise contour of the calendering zone, which contour extends continuously over the length of the calendering zone;
• heating the calendering surfaces to heat the calendering zone;
• guiding a still wetted web between the parallel calendering surfaces;
• and
• pressing the heated calendering surfaces towards each other to apply pressure along the entire length of the calendering zone to at least one surface of the web.

A method for calendering one side of a moist paper or cardboard web having two sides by passing the web through a single calendering zone having a length wherein a desired degree of smoothness is achieved by controlling the length of the calendering zone, comprising the steps of:

• providing means for moving the web along a first direction through the calendering zone;
• predetermined contour disposed on one side of the web, the bearing surface extending for substantially the length of the calendering zone along the first direction;
• providing means defining a calendering surface disposed on another side of the web substantially opposite the means defining the bearing surface, the calendering surface comprising a single continuous surface extending for substantially the length of the calendering zone and having a contour which complements the predetermined contour of the bearing surface, the calendering surface further extending along the first direction for a length at least equal to a length of the bearing surface so that during calendering the web is not in contact with the bearing surface without being in contact with the calendering surface;
• and
• providing a first support element disposed adjacent to the means defining the calendering surface for directly urging the means defining the calendering surface towards the web and the means defining the bearing surface to apply pressure to the web along the entire length of the calendering zone.

A method for calendering a moist paper or cardboard web moving at a web speed in a web travel direction to a predetermined degree of smoothness, the method comprising the steps of:

• A. providing a first calendering surface having a first continuous contour and a first length;
• B. providing a second calendering surface having a second continuous contour which is parallel to the first contour and a second length substantially equal to the first length;
• c. guiding the web between the first calendering surface and the second calendering surface;
• D. heating the first calendering surface and the second calendering surface;
• E. moving the first calendering surface and the second calendering surface towards each other to apply pressure to the web along the entire first length;
• and
• F. controlling the first and second calendering surface lengths so that the web is calendered to a predetermined degree of smoothness as it passes between the first and the second calendering surfaces.