Machine for forming a fibrous web

Abstract

In a machine for forming a layered fibrous web, at least two different fiber suspensions are led through a head box ( 10 ), the fiber suspensions are separated from each other by a blade device ( 18, 180 ), the fiber suspensions are supplied to a web forming device ( 24 ) and a water layer is formed having a transversely uniform flow at an outlet at the end of the blade device ( 18, 180 ), such that the water layer constitutes an extension of the blade device and thereby prevents mixing of the fiber suspensions. The blade device ( 18, 180 ) can be freely movable in a substantially vertical direction in order to permit an equalization of pressure between the fiber suspension layers separated by the blade device and thereby reducing wake effects downstream the edge of the blade device.

1 - 21 . (canceled) 
     
     
         22 : A paper machine including a head box comprising at least one fiber suspension separating blade device provided with at least one water outlet, the at least one outlet being arranged so as to form at least one water layer which constitutes an extension of the at least one blade device and has a transversely uniform flow rate, the at least one blade device is arranged to be freely movable in a substantially vertical direction in order to permit an equalization of pressure between the at least two fiber suspension layers separated by the at least one blade device and thereby reducing wake effects downstream of the at least one blade device. 
     
     
         23 : The paper machine according to  claim 22 , wherein the at least one blade device is provided with internal channels in which the water is pumped through the at least one blade device. 
     
     
         24 : The paper machine according to  claim 23 , wherein channels terminate at a distance from the at least one water outlet of the at least one blade device in order to provide a uniform flow rate of the water coming out from the at least one blade device. 
     
     
         25 : The paper machine according to  claim 22 , further comprising at least one pressure drop screen arranged inside the at least one blade device transversely to a direction of water flow. 
     
     
         26 : The paper machine according to  claim 25 , wherein the pressure drop screen is a porous material. 
     
     
         27 : The paper machine according to  claim 22 , wherein the height of the water outlet of the at least one blade device is constant whereby the thickness of the at least one water layer is constant and the transversely uniform flow has an adjustable flow rate by changing pumping pressure of the water. 
     
     
         28 : The paper machine according  claim 22 , further comprising a feed pipe arranged at an upstream end of the at least one blade device, the feed pipe supplies water to the at least one blade device perpendicular to a direction of water flow. 
     
     
         29 : The paper machine according to  claim 28 , wherein the feed pipe is connected to the at least one blade device in a rotationally fixed manner and the feed pipe coincides with the pivot axis of the at least one blade device. 
     
     
         30 : The paper machine according to  claim 22 , wherein the at least one blade device is elastically deformable, thereby permitting equalization of pressure between the at least two fiber suspension layers. 
     
     
         31 : The paper machine according to  claim 22 , wherein the at least one blade device is pivotally supported at an upstream end of the at least one blade device to pivot freely around a pivot axis perpendicular to a direction of intended water flow, thereby permitting equalization of pressure between the at least two fiber suspension layers. 
     
     
         32 : The paper machine according to  claim 22 , wherein the at least one blade device has a pair of parallel mutually spaced sheets. 
     
     
         33 : The paper machine according to  claim 22 , wherein the at least one blade device has a pair of sheets which converge towards each other in a direction of intended water flow, whereby the at least one water outlet is narrower than an inlet of the at least one blade device.