BANFORMNINGSPARTI Foer pappersmaskin, SOM AER AVSETT Foer Modernisering AV ETT PLANVIRAPARTI.

摘要

An improvement in a web-forming section of a paper machine intended as a modernization of a fourdrinier-wire part by which an improved formation of the web and an adjustable dewatering thereof by which better retention and desired distribution of fillers and fines is achieved. The web-forming section constitutes an improvement in an arrangement which includes a fourdrinier wire loop having a wire run which constitutes a lower wire of the web-forming section and which forms a single-wire initial portion of a dewatering zone of the web-forming section, and an upper wire unit which together with a run of the lower wire forms a two-wire dewatering zone within which dewatering takes place through the upper wire, wherein a first open faced forming roll is situated within the upper wire loop so that the two-wire dewatering zone begins in the region of the first forming roll, a horizontal plane tangent to the lower part of the first forming roll being substantially coplanar with the plane of the lower wire, a forming shoe within the fourdrinier wire loop having a curved deck which guides the joint run of the upper and lower wires, a reversing roll situated within the upper wire loop after the forming shoe and which guides a joint run of the upper and lower wires over an upwardly curved sector thereof until the joint run substantially coincides with the plane of the lower fourdrinier wire. Initial dewatering occurs in the single-wire initial portion of the dewatering zone to an appropriate extent through the lower wire. In the two-wire dewatering zone, dewatering occurs first within the sector of the first open forming roll in two directions through both the upper and lower wires whereupon within the region of the forming shoe, the dewatering takes place primarily upwardly through the upper wire.