Patent ID: 6521091
Filing Date: 2003-02-18
Classification: D21F

Abstract:
A method of producing a fibrous material web using a twin wire former, said method comprising the steps of:providing a twin wire former having a rotating dewatering element being a roll of diameter D greater than or equal to approximately 1800 mm, a set of two counter rotating continuous wires defining a stock inlet gap therebetween, and a headbox including a discharge slice; selecting a source of fiber stock suspension to be supplied to said headbox according to the calculation: F/(C*1000)>0.025 where F is the basis weight in g/m2 of the fiber stock suspension supplied to said stock inlet gap and C is the stock consistency in g/l of the fiber stock suspension in said headbox;feeding the fiber stock suspension through said discharge slice producing a suspension jet of thickness h into said stock inlet gap, said rotating dewatering element being curved, having a curvature radius R, a distance said continuous wires have contact with said rotating dewatering element being X and the ratio of R to h being less than approximately 45, wherein a length over which said continuous wires have contact with said rotating dewatering element X and h are selected so that the value resulting from the equation {square root over ((X*h))} is in the range of between approximately 140 mm and approximately 300 mm; and operating said twin wire former using said fiber stock suspension to produce the fibrous material web.