Swimming Roll Swimming Roll
The swimming roll (Fig. 6.4) was introduced into the paper industry in 1960 by Küsters (Germany). In principle the shell rotates around a fixed axial beam with bearings at each end. A pressurized oil chamber is placed between the shell and the beam which is sealed along the axis against the rest of the inside shell volume and against the roll ends. The oil pressure can deform the shell towards the coun¬teracting roll. The forces acting on the shell are carried by the axis supporting the oil chamber. High oil pressure tends to “blow up” the shell, resulting in more local load at the center of the press nip whereas reduced oil pressure will reduce the local load at the center compared to that at the edges. Loading of the roll to gen¬erate the nip pressure is done by external loading devices. A further example of this type of roll is the Voith Econip Roll. CC Roll
Introduced by Beloit in 1960, the shell of this crown control (CC) roll is supported by one shoe with hydrodynamic lubrication. The shoe can move in the nip direc¬tion in the fixed axial beam which takes the line load forces and deflects. Loading is external as with the swimming roll. Profile Roll
Introduced by Voith in 1980, the shell support of this roll is similar to that of the CC roll. One main feature is that the distance between its end bearings equals the distance of the bearings of the counteracting roll, therefore it is also called the equidistance roll. Loading is external.