Papermaking machine having a single wire run and a double wire run over a downwardly curving dewatering box

Abstract

Abstract 1. In a paper machine, a wire section having a first wire forming a single-wire initial portion with first dewatering means, by the aid of which water is removed from the pulp web, and which wire section after said initial portion comprises a second wire creating a two-wire portion, second dewatering means guiding said two-wire portion to be curved downwardly at least at its initial end, characterized in that said single-wire initial portion of the wire section has a length such that when dewatering of the pulp web is cautiously performed in said single-wire initial portion, the pulp web achieves before the two-wire portion a degree of felting such that the fibres in the pulp web are no longer able to move appreciably with reference to each other, and that said two-wire portion is guided by said second dewatering means to curve downwardly so that water is removed in connection with said second dewatering means mainly by effect of centrifugal force through the upper wire of the two-wire portion and in a direction opposite to that in the single-wire initial portion, the object being to reduce the escape of additives of the pulp web, such as fillers, and of fine constituents of the pulp web, and to increase the splitting strength of the paper that is being manufactured, wherein said second dewatering means comprises a dewatering box which has means for forming several consecutive chambers, means for adjusting the pressures in said chambers in order to achieve a symmetrical fibre structure of the pulp web, of which chambers in the one which is first in the direction if travel of the pulp web or in those which are first in said direction a vacuum has been arranged to act, and in the subsequent chamber or chambers, a positive pressure has been arranged to act.

Inventors

• 👤 M Kankaanpaa

Bibliographic Details