Sheet-forming device

Abstract

The invention relates to a sheet-forming device (1) for producing a two-layer or multilayer fiber web (2) from at least two fiber suspensions (3), at least comprising a first screen (4) onto which a first, preferably single-layer headbox (5) applies a first layer (6) of fiber suspension (3) and which is guided together with the applied layer (6) of fiber suspension (3) via a stationary screen table (7) and multiple dewatering elements (8); a second headbox (9) that applies a second layer (10) of fiber suspension (3) onto the first fiber suspension (3) layer (6) that rests on the first screen (4); and a second screen (11) which forms a double screen zone (12) with the first screen (4) at least along some sections, said zone having a wedge-shaped inlet gap (13). The sheet-forming device (1) according to the invention comprises a dewatering element (17) on the lower face of the first screen (4) in the application region (B), preferably upstream of where the second layer (10) of fiber suspension (3) is applied onto the first layer (6) of fiber suspension (3), when seen in the running direction (S) of the screen, said dewatering element guiding the first screen (4) and having a guiding surface (17.A) that bends downwards at a bend angle (17.W) = 1°, preferably = 2°, in particular = 3°. The sheet-forming device further comprises at least one inlet strip (21) which is arranged in the region of the wedge-shaped inlet gap (13) and / or downstream of the region of the wedge-shaped inlet gap (13), when seen in the running direction (S) of the screen, said strip being supported by means of at least one flexible element (22) and being pressable with a selectable force (22.F) against the first screen (4) and / or against the screen sandwich formed by the two screens (4, 11) and the layers (6, 10) that lie between said screens.

Description

technical field [0001] The invention relates to a sheet forming apparatus for producing a two- or multilayer fibrous web, in particular a board or packaging web, from at least two fibrous suspensions, comprising at least a first screen preferably formed as a longitudinal screen, A first and preferably a single-layer headbox applies a first layer of fiber suspension onto said first screen, and said first screen together with the applied first layer of fiber suspension in a stationary screen table and multiple Guided on a dewatering element, a second and preferably single-layer headbox, which applies a second layer of fiber suspension to the first layer of fiber suspension on the first screen, and the preferred topography A second sieve forming the upper sieve, which together with the first sieve at least in sections forms a double screen zone with a wedge-shaped lead-in gap, wherein in the double-screen zone the second sieve guided by the lead-in roller runs through A pluralit...

AI Technical Summary

Problems solved by technology

But the incoming and to-be-formed fibrous web has a distinct mass density difference in its z-direction, i.e. height direction, due to the application by the secondary headbox

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