Machine for producing a fibrous web

Abstract

A gap former for forming a fibrous web from a fibrous suspension supplied via a headbox, having a top fabric (3, 28) and a carrier or bottom fabric (2, 27), is defined by the fact that the carrier fabric (2, 27) has a greater thickness than the top fabric (3, 28).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 10 2004 044 570.2 filed on Sep. 15, 2004, the disclosure of which is expressly incorporated by reference herein in its entirety. BACKGROUND OF INVENTION [0002] 1. Field of the Invention [0003] The invention relates to a gap former for forming a fibrous web from a fibrous suspension supplied via a headbox, having a top fabric and a carrier or bottom fabric. [0004] 2. Discussion of Background Information [0005] U.S. Pat. Nos. 5,826,627 and 5,152,326 disclose fabrics which consist of a plurality of woven layers with weft and warp threads, the layers being connected to one another by individual threads. In this case there are different possible ways of connecting the woven layers to one another. [0006] In the case of paper webs produced by means of the known fabrics, there is the problem that the printing quality is not always adequate, which manif...

AI Technical Summary

Benefits of technology

[0007] The object of the invention is to improve a gap former of the type mentioned as the beginning in such a way that it is also suitable for the production of high-quality SC papers.

[0009] According to the invention, use is made of fabrics which, as compared with fabrics known from the prior art, cause less misting in the exit gap of the fabrics. This is important in particular at speeds of more than 1550 m / min. By means of the invention, the printing quality of the paper can be improved. A paper web of high quality is produced, which has no or barely any defects even at high production speed.

[0011] Likewise, it also proves to be advantageous if the closing is or comprises an SSB fabric (SSB=self stitched binding) and / or comprises a plurality of layers of fabrics.

Problems solved by technology

In the case of paper webs produced by means of the known fabrics, there is the problem that the printing quality is not always adequate, which manifests itself, for example, by the lack of printed dots (missing dots) or else by means of an excessively high roughness (PPS roughness).

There are also problems with the runnability of the paper web, in particular in the fabric separation region, where it is possible for water to be sprayed from the wet-end clothing running on the top side.

Since it also contains fibrous material and ash, the sprayed water produces soiling inside and outside the machine.

Drops of water dropping on to the fibrous web led out of the wet end and accessible from above, which drops have been produced by condensation of the water mist, soil the fibrous web and lower its quality.

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