Apparatus and method for the manufacture of fibrous webs

In apparatus for the manufacture of a wet laid fibrous web, an improved headbox capable of producing a foam-fiber dispersion from an unfoamed feedstock comprising air and papermaking fibers dispersed in a foamable aqueous carrier medium comprising water and a surfactant and directing resulting foam-fiber furnish onto a forming wire which comprises

• a closed channel longitudinal headbox of rectangular cross section having parallel planar front and back walls and parallel planar top and bottom walls,
• a longitudinal outlet in the lowermost portion of said front wall for dispensing foam-fiber furnish through a slice or nozzle onto a forming wire,
• a first longitudinal array of fluid inlet nozzles uniformly spaced along the upper wall of said headbox channel for connection to a supply of pressurized feedstock arranged to forcibly discharge feedstock onto the bottom wall of said headbox along a vertical plane perpendicular thereto, and
• a second longitudinal array of fluid inlet nozzles uniformly spaced along the rear wall of said headbox channel for connection to a supply of pressurized feedstock arranged to forcibly discharge feedstock onto the front wall of said headbox along a plane parellel to the plane of said bottom wall thereof and perpendicular to the plane of said first array of nozzles in non-intersecting relationship with feedstock discharged from said first array to forcibly discharge feedstock onto the front wall of said headbox, thereby producing a foam-fiber furnish in said headbox immediately prior to its discharge through said outlet onto a forming wire.