Method and device for manufacturing a fibrous web
In the production of a fiber web, for paper or cardboard, while the web (12) is still wet it is stretched laterally to set the web characteristics and particularly the web structure and/or the fiber orientation. The web (12) is stretched laterally, while still wet and with a solid content of 5-65% a...
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Format: | Patent |
Sprache: | eng ; fre ; ger |
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Zusammenfassung: | In the production of a fiber web, for paper or cardboard, while the web (12) is still wet it is stretched laterally to set the web characteristics and particularly the web structure and/or the fiber orientation. The web (12) is stretched laterally, while still wet and with a solid content of 5-65% and preferably 15-25%. The wet web (12) is transferred to a continuous and elastic belt (14). The belt (14) is stretched longitudinally before the transfer point (A), and the stretch is measured in different directions. The longitudinal stretch on the belt (14) results in a lateral contraction, to give a set lateral reassertion after the transfer point (A) which carries the web (12) with it and stretches the web (12) laterally. The stretch behavior of the elastic belt (14) is measured differently for width and thickness so that, on a longitudinal expansion and contraction, only a width contraction or expansion takes place without a change in the belt thickness. The elastic belt (14) is stretched longitudinally directly in front of the web transfer point (A) by at least one powered roller (16), and preferably at least two rollers (16,20,22). The web (12) is transferred to the elastic belt (14) at the zone of the final belt tensioning roller (16). The elastic belt (14) also acts as a press blanket for the web (12), or as a transfer belt. A belt (14) is used which has different stretch characteristics across its width, and with a closed or porous surface. The web (12) is transferred to the elastic belt (14) by a carrier (18) and especially a fourdrinier, or a transfer belt. The lateral stretch imposed on the web (12) increases the lateral orientation of the web fibers and sets the web structure. An Independent claim is included for a section of a papermaking or cardboard production machine (10), with an elastic belt (14) and a powered roller (16) to impose a lateral stretch on the web (12). |
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