Formation system of a machine for manufacturing a fibrous web

摘要

Double screen former for a machine for producing a fibrous web comprises a headbox (2) equipped with a turbulator (3) and an outlet nozzle (4) that is subdivided by several lamellae (18) and has a restrictor at the tip. The ratio of the length of the lamellae to the length of the nozzle is at least 0.5 and the ratio of the depth of immersion of the restrictor to the nozzle slit width is at least 1 and the pulp stream from the nozzle has a free jet length (between nozzle and screen) of 300 mm or less.