Process and headbox for a machine for making a fibrous web

摘要

Production of fibrous material web from a pulp suspension that is supplied from a headbox having a headbox nozzle (18) with a lamella (10) comprises supplying a pulp suspension stream toward the headbox nozzle; and generating cross flows inside the pulp suspension stream due to structures (14) one of in and on a surface of the lamella, where the cross flows lead to shear flows in the suspension stream. An Independent claim is also included for a process for forming a headbox for producing a fibrous material web from a pulp suspension to form of a paper or cardboard web comprising providing a structured surface with a structure of the lamella, where the structured surface is arranged to generate cross flows inside the pulp suspension where the cross flows lead to shear flows in the suspension stream.