Calender for polishing both sides of paper web has two roller stacks of hard and soft outer and intermediate rollers, with second stack having reverse order to first stack configuration

摘要

The calender to act on both sides of a web, and especially of paper, has a twin-stack of rollers each with four rollers. One roller stack (2) has a hard outer (4) and intermediate roller (6) and a soft outer (7) and intermediate (5) roller, with all the rollers of different diameters. The other roller stack is identical but has a reverse order. The other roller stack (3) has rollers (8-11) identical to those in the first stack (2), but in a reverse order in relation to the direction (D) of web travel. The diameter of the intermediate rollers (5,6,9,10) is smaller than the diameters of the outer rollers (4,7,8,11). The diameter of the soft outer rollers (7,8) is larger than the diameter of the hard outer rollers (4,11). The two roller stacks (2,3) are of separate stacked rollers, next to each other. They are offset from each other, in height, so that the uppermost nip of the second stack (3) is higher than the lowest nip of the first stack (2). Or the two roller stacks (2,3) are in a common stack deployment, with separate draw force characteristics. The two roller stacks (2,3) have a web entry from above.