Method for control of the curl of paper in the treatment of surface-sized paper, and finishing section of a paper machine

Abstract

The invention relates to a method in the treatment of suface-sized paper, in particular fine paper, in a finishing section of a paper machine. In the method a paper web (W) is first dried in a forward dryer section (D) of the paper machine in several successive downward open drying groups (G1...g6) that apply single-wire draw, after which the paper web (W) is finished in the finishing section. In the finishing section the web (W) is surface-sized in a surface-sizing unit (20) and dried. According to the invention, in the method, the surface-sized paper web (W) is mainly dried by means of contact-free drying. The web (W) is dried at least partly by means of airbone web-dryers (31, 32, 34, 36) or by means of impingement drying. In the method, the power of the airbone web-drying / impingement drying is regulated on both sides of the web (W) such that the tendency of curling created in the web (W) in the forward dryer section (D) can be controlled. In addition, the invention relates to a finishing section of a paper machine in the treatment of surface-sized paper, in particular fine paper, in the paper finishing section. Before the finishing section, the paper machine comprises a forward dryer section (D) in which there are several successive downward open drying groups (G1...G6) that apply single-wire draw. The finishing section comprises surface-sizing devices (20) and drying means. According to the invention, the drying means of the finishing section are mainly based on contact-free drying. At least one of the means are airborne web-dryers / impingement dryers (31, 32, 35, 36), whose power can be regulated such that the tendency of curling of the web can be controlled by the effect of drying applied on the different sides of the web (W).

Description

technical field [0001] The invention relates to a method for the treatment of surface-sized paper, especially fine paper, in the finishing section of a paper machine according to the preamble of claim 1 . The invention also relates to a method according to the preamble of claim 4 . [0002] Furthermore, the invention relates to a finishing section of a paper machine for processing surface-sized paper, in particular fine paper, according to the preamble of claim 11 . The invention also relates to a finishing section of a paper machine according to the preamble of claim 15 . Background technique [0003] As is known in the prior art, multiple dryer groups of a paper machine employ twin-wire draws and / or single-wire draws. In twin-wire draw, the dryer group consists of two wires, one of which presses the web from above and the other from below against the heated cylinder surface. Between the dryer rows, which are usually horizontal, the web is free unsupported draw, which is...

AI Technical Summary

Problems solved by technology

Between the dryer rows, which are usually horizontal, the web is free unsupported draw, which is susceptible to oscillations, which can lead to web breaks, especially when the web is still relatively wet , so the strength of the web is low

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