GB1361083A - Headbox for a paper-making machine - Google Patents

Abstract

1361083 Headboxes J M VOITH GmbH 6 Aug 1971 [7 Aug 1970] 37091/71 Heading D2A A headbox for a paper-making machine comprises a stock inlet tube 1, distribution tubes 2, a flow duct 3 extending over the machine width, and fine-distribution tubes 4 leading to a slice 10, the part of the duct 3 at the tubes 4 so decreasing in the direction of stock flow that the stock flow speed and the deflection angle of the stock flow at the various inlets 5 of the tubes 4 are equal. The duct 3 has an outlet 6 leading to a sump 7 overflowing to a trough 8, the flow through the outlet being controlled by means in the outlet or by controlling the height of stock in the sump 7. The slice includes a bottom lip 11 and a top lip 12, the latter having a backup buffer, cushion or pad. In a modification, Figs. 2 and 3 (not shown), the tubes 2 converge, the inlet ends of the tubes 2 being circular and spaced so as to provide relatively wide areas between them on which fibres in the stock will not be retained and their outlet ends being pentagonal or hexagonal in cross-section and taking up substantially the whole crosssection of the duct 3. The tubes 4 are similar to the tubes 2 but of smaller diameter, and the tubes 2 and 4 are chamfered asymetrically by circular recesses at their inlets to facilitate stock flow, Figs. 6 and 7 (not shown). The recesses can be larger or smaller than the tube diameters. The ends at least of the tubes 2 and 4 diverge to form diffusers. The outlet 6 of the duct 3 may be omitted.