Importance

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Abstract

The invention relates to a headbox (10) for a paper/boardmaking machine. The headbox (10) including a stock flow header (11) and, following the stock flow header, a piping system such as an inlet pipe manifold, and/or a turbulence generator (14) and a tapered slice (15), wherefrom the stock is passed onto the forming wire (H.sub.1). The construction of said headbox further includes a flow header (J) for a dilution liquid the flow header having connected thereto an inlet channel (S.sub.1), a return pipe (S.sub.2) and outlet channels (D.sub.1, D.sub.2, D.sub.3, . . . ) that are distributed over the full length of said flow channel for passing the dilution water to control valves (V.sub.1, V.sub.2, . . . ) and, therefrom, further to different points along the cross-machine width of the headbox so as to mix with the stock delivered from the stock flow header (11) in order to control the consistency of the stock to a desired value, thus accomplishing the control of the web basis weight profile in cross-machine direction over the headbox. The dilution water flow header (J) is structured to accomplish mixing of the dilution water flow (L.sub.1) so as to make the consistency of the dilution water flow (L.sub.1) homogeneous both along the entire length of the flow header (J) and in cross sections of the flow taken in planes perpendicular to the longitudinal axis of the flow header.

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First Claim