Patent ID: 6679974
Filing Date: 2004-01-20
Classification: D21F

Abstract:
A turbulence generator in a headbox of a paper machine, the headbox having a width, and a slice opening, the turbulence generator comprising:a plurality of superimposed turbulence pipes arranged in rows extending across the entire width of the headbox, through which a stock suspension flow to be conducted from the headbox through the slice opening to a web former is arranged to flow; and portions of each turbulence pipe which define a stepped expansion of the flow cross-section area in the space between an inlet end and an outlet end of each pipe, the stepped expansion of each turbulence pipe being positioned at an expansion spot, wherein in superimposed pipe rows, the distance of the expansion spot of the turbulence pipes from the slice opening of the headbox in association with the pipe rows, is different in that at the slice opening, in the headbox a different turbulence prevails in different layers of the stock suspension flow; and wherein the superimposed rows of turbulence pipes include a centermost row of pipes, and wherein the expansion spots of the pipes within a row are positioned closer to the slice opening of the headbox, the closer said pipe row is to the centermost pipe row.