Former and headbox for said former

Abstract

A former for a machine for the production of a fibrous web, particularly a paper or cardboard web including a headbox equipped with at least one stock suspension feed, one turbulence block equipped with several channels and / or a tube generator equipped with several channels, and a headbox nozzle whose suspension jet strikes an exposed or open surface of a dewatering belt, specifically a wire. Turbulence generating elements are allocated to at least a section of the channels and / or the headbox nozzle, in order to create turbulent flows in the suspension substreams in the channels, or in the headbox nozzle. The side of the suspension stream facing away from the dewatering belt is covered at least partially by a wall. A danger of the suspension stream bursting open is reduced to a minimum. In addition, swirling motions of considerably higher intensity than occur on conventional Fourdrinier wire formers are now permissible.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a machine a machine for the production of a fibrous web, and, more particularly, to a former and former headbox. [0003] 2. Description of the Related Art [0004] With suction formers, a longitudinal orientation of the fibers occurs at an appropriate increase in the operating speed of the paper machine in question. This may limit the scope of application of such suction formers to low operational speeds. [0005] A relatively strong transverse orientation of the fibers, as well as a low longitudinal / transverse ratio can be achieved (see for example U.S. Pat. No. 5,876,364) through transverse movements that are indicated through various swirl-producing bodies in the turbulence block. However, a consequence of these transverse motions is the inherent danger of the suspension stream that is delivered by the headbox of the respective former bursting open when encountering an open surface, fo...

AI Technical Summary

Benefits of technology

[0012] In accordance with an additional aspect of the present invention a former, specifically a suction former or twin wire former of a machine for the production of a fibrous web, specifically a paper or cardboard web is provided or this purpose; comprising a headbox that is equipped with at least one stock suspension feed, one turbulence block equipped with several channels and / or a tube generator equipped with several channels and a headbox nozzle. Turbulence generating elements are allocated to at least a section of the channels in order to create turbulent flows that rotate in the same direction in the suspension substreams in the channels. Same directional turbulence movement suppresses the undesirable stripes.

[0021] In order to attain a sufficient effect, the headbox nozzle should be as short as possible. The headbox nozzle should preferably be shorter than approximately 400 mm. It is also advantageous if the outlet cross section of the channels or pipes is at least essentially round, since a square outlet cross section would dampen the effect.

Problems solved by technology

This may limit the scope of application of such suction formers to low operational speeds.

However, a consequence of these transverse motions is the inherent danger of the suspension stream that is delivered by the headbox of the respective former bursting open when encountering an open surface, for example on the Fourdrinier wire.

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