Multiple ply dewatering screen particularly for a web forming part of a paper making machine

摘要

A paper web forming screen includes two screen fabric plies made of longitudinal and traverse filamentary elements. The upper ply is made of longitudinal and traverse mono- or multi- or staple-filaments whereas a part of longitudinal and/or traverse filamentary elements in the lower ply is made of mono- or multi- or staple-filaments and other parts of non-twisted bundles of component filaments. A component filament in respective bundles is passed at different tie points over traverse mono- or multi- or staple-filaments in the upper ply to replace a longitudinal mono- or multi- or staple-filament in the upper ply. The latter mono- or multi- or staple-filament is passed either below the traverse mono- or multi- or staple-filaments in the tie points or below traverse filaments in the lower ply. The component filaments in the bundles are of the same thickness as the longitudinal and traverse mono- or multi- or staple-filaments in the upper ply.