Twin-fourdrinier papermaking machine, taking wet pulp between them from the stock inlet, passes over the cladding of a suction box with an initial water extraction zone with a perforated and structured cladding surface

摘要

The papermaking machine with a twin-fourdrinier structure, taking the pulp between them from the stock inlet to be converted into a web, passes over an initial suction box to extract water from the wet pulp. The suction box has a cladding (16) on the side towards the fourdriniers at the first water extraction zone (15.1), with a perforated surface (27) and a number of openings (28,29). The openings provide an open surface (Ao) of 10-60% of the total surface area (Ag) and preferably 15-40%. The cladding has an irregular surface structure (S1) and an additional surface pattern (N) of straight grooves (30) at different alignments.