Forming section for forming a fibrous web, a papermaking machine comprising a forming section and a method of forming a fibrous web

Abstract

The invention relates to a forming section () for forming a fibrous web (W). The forming section () comprises a first forming fabric () arranged to run in a loop supported by guide elements () and a second forming fabric () arranged to run in a loop supported by guide elements (). The second forming fabric () is arranged so inrelation to the first forming fabric () that the two forming fabrics () converge towards each other to form an inlet gap () into which stock can be injected. A forming roll () is arranged within the loop of the second forming fabric () to guide the second forming fabric () into the inlet gap () and to guide the first and the second forming fabric () along a part of their path which is common to both the first and the secondforming fabric () and which begins at the inlet gap. The forming roll () comprises a flexible tubular jacket () which is arranged to run in a loop around an axis of rotation (A) that extends in a direction perpendicular to the direction in which the first and second forming fabric () are arranged to run and the forming roll further () comprises a support ledge () located inside the loop of the flexible tubular jacket ()and extending in a direction parallel to the axis of rotation (A) of the flexible tubular jacket (). The support ledge () can press the flexible tubular jacket () in a direction outwards away from the axis of rotation (A) such that, in the area in which the flexible tubular jacket () is pressed outwards by the support ledge (), the flexible tubular jacket () is caused to follow a path with a radius of curvature which is smaller than theradius of curvature of the flexible tubular jacket () outside this area. The invention also relates to a method of forming a fibrous web.