A METHOD OF PRE-PRESSING FIBRE MATERIAL IN THE MANUFACTURE OF BOARD PRODUCTS

摘要

In a method of pre-pressing a formed web of finely-divided lignocellulosic fibre material prior to pressing the web to a finished state in the continuous manufacture of board material, the fibre material is compacted and pressed successively in an entry section (7) of a pre-press (6) subsequent to being formed into a web (11) and subsequent to a first compression and expansion. The web is compressed in this latter pressing process to a density close to the density of the web after the first compression, whereafter the web is allowed to expand to a controlled limited extent in a pre-press expansion section (9), and thereafter transferred to the finishing press. Steam (A, B) is injected into the web (9) when the web is located in the pre-press (6).