DE20107844U1 - Dryer fabric - Google Patents

Description

The invention relates to a drying screen of a drying section of a machine for producing and/or finishing a paper, cardboard, tissue or other fibrous web, which guides the fibrous web and partially wraps around at least one heated, rotating drying cylinder, wherein the fibrous web comes into contact with the drying cylinder.

To dry the fibrous web, it is guided over guide rollers and heated drying cylinders in drying groups of the drying section, generally supported by a drying screen. The fibrous web comes into contact with the smooth surface of the drying cylinder. Due to the resulting adhesion of the fibrous web to the drying cylinder, the fibrous web tends to run along with the drying cylinder when the drying screen is guided away. This is particularly problematic when the fibrous web has a high moisture content, i.e. at the beginning of the drying section.

To counteract this, the drying groups at the beginning of the drying section are made very short and trains, i.e. differential speeds, are built up between the drying groups. This is not only time-consuming, but also puts strain on the fiber web.

The object of the invention is therefore to counteract the adhesion of the fibrous web to the drying cylinder using the simplest possible means.

According to the invention, the object was achieved in that the drying fabric has increased adhesion in adhesion areas that run opposite the edge areas of the fibrous web. In doing so, the knowledge that the edge areas of the fibrous web in particular adhere more strongly to the drying cylinder was taken into account. It is therefore sufficient to arrange adhesion areas opposite the edges of the fibrous web.

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The adhesive areas of the drying fabric should each cover an edge area of the fibrous web with a width of 30 to 100 mm.

One way to increase adhesion is for the drying fabric to have a smooth surface in the adhesion areas on the side facing the fibrous web. On its own or in combination with the smooth surface, it is also possible for the drying fabric to have a lower air permeability in the adhesion areas than in the main area in between. The adhesion areas should preferably even be airtight.
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This design of the adhesion areas is made possible in particular by filling the drying screen in the adhesion areas with a polymer, preferably polyurethane.

The impairment of air permeability in the adhesion areas hinders rear ventilation and thus increases the adhesion of the fibrous web to the drying fabric. On the other hand, however, this impairs evaporation and thus the drying of the fibrous web in the edge areas. However, this can be tolerated in the edge areas, as these will be cut off later anyway and/or usually tend to overdry anyway.

Dryer fabrics designed in this way should be used in particular in drying groups of the drying section in which only one side of the fibrous web comes into contact with heated drying cylinders. This is essentially due to the fact that in these drying groups the fibrous web does not have to be transferred between drying fabrics.

The invention will be explained in more detail below using an exemplary embodiment. In the attached drawing, the figure shows a cross section through the edge of a drying screen 2.

(1013772.DOC) PF11261 &Oacgr;&egr;'· J

For drying, the fibrous web 1 is guided by the drying wire 2 in the single-row drying group of a drying section, alternately over guide rollers and heated, rotating drying cylinders 3, where it comes into contact with the drying cylinders 3.
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In order to be able to guide the fibrous web 1 away from the drying cylinder 3 relatively easily and safely after partial wrapping, the drying fabric 2 has increased adhesion in adhesion regions 4 which run opposite the edge regions of the fibrous web 1.
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For this purpose, the drying fabric 2 is filled with polyurethane in the adhesion areas 4. The adhesion areas 4 are not only airtight, but also smooth compared to the fibrous web 1.

Since the edge regions of the fibrous web 1 in particular tend to have an increased adhesion to the smooth drying cylinder 3, it is sufficient if the adhesion regions 4 each cover an edge region of the fibrous web 1 with a width between 30 and 100 mm.

(1013772.DOC) PF11261 at Z*5001-05-£lV/MVIL *: ··· · ·· ·

Claims (7)

1. Drying fabric ( 2 ) of a drying section of a machine for producing and/or finishing a paper, cardboard, tissue or other fibrous web ( 1 ), which guides the fibrous web ( 1 ) and partially wraps around at least one heated, rotating drying cylinder ( 3 ), wherein the fibrous web ( 1 ) comes into contact with the drying cylinder ( 3 ), characterized in that the drying fabric ( 2 ) has increased adhesion in adhesion regions ( 4 ) which run opposite the edge regions of the fibrous web ( 1 ). 2. Drying fabric ( 2 ) according to claim 1, characterized in that the adhesive regions ( 4 ) of the drying fabric ( 2 ) each cover an edge region of the fibrous web ( 1 ) with a width of 30 to 100 mm. 3. Drying screen ( 2 ) according to claim 1 or 2, characterized in that the drying screen ( 2 ) is filled with a polymer, preferably polyurethane, in the adhesion areas ( 4 ). 4. Drying screen ( 2 ) according to one of the preceding claims, characterized in that the drying screen ( 2 ) has a lower air permeability in the adhesion regions ( 4 ) than in the main region ( 5 ) therebetween. 5. Drying screen ( 2 ) according to one of the preceding claims, characterized in that the drying screen ( 2 ) is designed to be air-impermeable in the adhesion areas ( 4 ). 6. Drying fabric ( 2 ) according to one of the preceding claims, characterized in that the drying fabric ( 2 ) has a smooth surface in the adhesion regions ( 4 ) on the side facing the fibrous web ( 1 ). 7. Application of the drying fabric ( 2 ) designed according to one of the preceding claims, in drying groups of the drying section in which only one side of the fibrous web ( 1 ) comes into contact with heated drying cylinders ( 3 ).