Three roll press

摘要

The invention relates to a roll press including at least three rolls forming several press nips for the treatment of a web of material. One press roll comprises a very flexible roll shell which is rotatable around a fixed support and is mounted on the support by at least one support element which has a concave support surface for defining a wide press nip with a cylindrical backing roll. The backing roll forms an additional press nip with at least one not sag-controlled roll. To obtain as uniform as possible a press nip between the backing roll and at least one additional roll which is without sag control, the circumference of the roll shell of the backing roll decreases axially towards its ends, i.e., that roll may be crowned. In addition, the backing roll may have its own roll shell support elements which are either in the press plane or are inclined slightly out of the press plane and/or the hydraulic pressure fluid supplied to the press roll and to the backing roll is adapted to supply a greater pressing force by the press roll. Optionally, a fourth press roll may form a nip with the additional roll. A felt passes through each nip.