Web-forming method and apparatus

Abstract

A web-forming method and apparatus particularly suited for cellulose pulp. The web is initially formed on a rotary wire cylinder which has a horizontal axis and a crest situated at the highest part of the cylinder over the horizontal axis, the cylinder during rotation thus having an upwardly travelling side which turns upwardly toward the crest and a downwardly travelling side which turns downwardly from the crest. At the upwardly travelling side of the cylinder is a headbox having its slice situated adjacent the crest for projecting onto the rotating cylinder a pulp slurry jet at a speed greater than the peripheral speed of the cylinder, so that the deposited pulp slurry will start to form a web while turning with the cylinder up to and then downwardly from the crest thereof. An outer wire has a portion wrapped partially around the cylinder, through an angle of at least 180.degree., and the web which initially forms freely on the cylinder is compressed between the outer wire and the cylinder with the outer wire travelling with the cylinder, so that in this way dewatering is accelerated. The outer endless wire is guided around a pickup roll to travel onto the latter from the cylinder while continuing to carry the web, so that in this way the web is detached from the cylinder and is carried away from the latter with the outer wire before the latter returns to the cylinder.