GB1398487A - Headbox for a web forming machine - Google Patents

Abstract

1398487 Paper-making machines DOMINION ENG WORKS Ltd 14 May 1973 [20 June 1972] 22867/73 Heading D2A A headbox for a paper-making machine, e.g. a twin-wire machine (Fig. 2) or a cylinder machine (Fig. 3) comprises an elongate header 12, a mixing chamber 16 having a back wall 18 and spaced top and bottom faces 20, 22 converging towards an exit throat 24, a plurality of pipes 14 connecting the header 12 with the mixing chamber and entering one face of the chamber near the back wall 18 such that stock entering the mixing chamber expands and impinges against the opposite face thereby increasing the macro-tunbulence of the stock, and a diverging diffuser section 30 having a divergence angle of not more than 7 degrees downstream of the throat 24, the ratio of the mixing chamber length (L) to its depth (A) being at least 6:1. Preferably the ratio of the depth (A) to the depth (E) of throat 24 is greater than 3 with that portion 26 of face 20 which defines the throat being inclined to the remainder of the face 20 at 35-55‹, preferably 45‹ from the diffuser section 30 stock passes to an approach section 40 where it is divided by walls 42 into parallel sub-flows before being passed to slice plates 52, 54. The upper slice plate 52 can be pivotally adjusted by actuators 55, and fine adjustment of the slice can be made by adjusting a slidably mounted lip extension 60.