Double sieve former manufacturing paper web, has forming box with bearing point vertically above its center of gravity

摘要

The forming box (13) has at least one bearing point (L) lying vertically above its center of gravity (S). The bearing point is located in an angular range relative to the vertical, of preferably -3[deg] to +3[deg], above its center of gravity. The box has in-line bearing points, the line being approximately vertical. Over the width of the web, this forms an angle (beta ) with the run of the double sieve belt run following the forming unit (7), and intersects the center of gravity of the box. The bearing point (L) is preferably 900-1250 mm above the center of gravity. The box is pressed against the running sieve belt (5) by a controlled actuator (18). This comprises two units (19), one for each side of the box. They are pressure cylinders connected to a common hydraulic- or pneumatic source; electrical or electromechanical units may be used as an alternative. A damper is included. Skimmer- or deflector strips are used on the box. Suction applied to the box is preferably 100-200 mbar. The box is rigid, and carries fixed forming strips (14). The sieve belts run vertically, or are inclined at an angle of up to 75[deg] with respect to the vertical. Following the upper deflection unit (15) the sieve belts run down at an angle of preferably 15[deg] to 45[deg] with respect to the horizontal. This unit (15) is a deflection roller, preferably with suction. The forming unit (7) is a roller with zone suction. The roller train is further detailed.