FORMING OF A PAPER OR BOARD WEB IN A TWIN-WIRE FORMER OR IN A TWIN-WIRE SECTION OF A FORMER

摘要

Fibrous stock is supplied by a paper or board machine headbox ( 1 ) between looped forming wires ( 11, 12 ). Water is removed in a two part first dewatering zone (Z 1 ), the first part formed by a suction forming roll engaging a forming wire ( 12 ) and the second part formed by a fixed forming shoe engaging opposite a forming wire ( 11 ). The wires ( 11, 12 ) are guided so the first dewatering zone causes essentially non-pulsating dewatering in the stock. Water is removed in a second dewatering zone (Z 2 ) formed by fixed dewatering blades ( 21 ) on the other side of the wires ( 11, 12 ) and supported against the stock therebetween ( 21 ) and on the opposite side of the wires ( 11, 12 ) by dewatering blades ( 24 ), loaded in a controlled manner against the fixed dewatering blades ( 21 ) at gaps ( 22 ) between these so that pulsating dewatering is caused in the second zone (Z 2 ).