Headbox with a vertical partition between perforated rolls

Claim 1

A headbox for a machine used in production of a fiber material web from a fiber suspension, said headbox comprising: a main chamber defined by a bottom and two side walls which extend parallel to the longitudinal machine direction such that the fiber suspension can flow through said main chamber in the longitudinal direction of the machine; a first perforated roll and a machine-wide feed channel disposed in and at an upstream end of said main chamber, and a second perforated roll and a machine wide nozzle type outlet channel disposed in and at a downstream end of said main chamber; a partition disposed in said main chamber between said first and second perforated rolls, said partition extending generally vertically and transverse to the longitudinal machine direction, said partition being vertically adjustable and defining a machine-wide channel section having a variable height; said partition having a downstream outside surface which is inclined from top to bottom relative to the vertical such that said variable height of said channel section increases in the direction of flow, said downstream outside surface comprising at least three abutted surfaces, at least two of said at least three abutted surfaces having a curved surface, each said abutted surface having opposite ends and defining two lines which are disposed tangent to said abutted surface at each respective said opposite end, said tangent lines which are disposed adjacent to each other and to a common adjoining edge defining a respective obtuse angle therebetween, said downstream outside surface structured and arranged to provide uniform separation of said suspension flow from said downstream outside surface and maintenance of uniform microturbulence within said suspension flow across the machine width.