Patent ID: 6432275
Filing Date: 2002-08-13
Classification: D21F

Abstract:
A headbox for a paper/board machine by whose means the basis weight of the web can be regulated, wherein the headbox comprises a stock inlet header (J1), which becomes narrower towards its end, tubes (11a1, 11a2 . . . ) in a tube bank (11), which tubes open in the stock inlet header (J1) across the machine width and which tubes are connected with thickening elements (12a1, 12a2 . . . ) across the machine width, in which connection a flow (L1) is removed from the thickening element into the duct (D1) and said flow (L1) to be removed is regulated by means of a valve (V1, V2 . . . ), and from which thickening element (12a1, 12a2 . . . ) a tube (14a1, 14a2 . . . ) for a flow (L2) of higher consistency is provided, which flow is passed further in the headbox, and that, by means of the pressure present in the inlet header (J1), the flow (L2) that departs from the thickening elements (12a1, 12a2 . . . ) is always kept invariable irrespective of the amount of flow (L1) that is removed through the thickening element (12a1, 12a2 . . . ).