| 摘要 |
<p>A headbox (20) has a tube bank (28) of tubes (26) arranged in machine direction rows. The tubes (26) extend from an outlet wall (30) of a header to the inlet of a nozzle (42). The upper and lower walls (44, 46) of the nozzle (42) converge toward the nozzle outlet (48), and planes extending from the walls (nozzle roof and apron) converge to define an imaginary centerline extending in the cross-machine direction. The rows of tubes (26) lie along radially extending planes defined with respect to the centerline. The injection ends of the tubes define a cylindrical surface (64) extending between the nozzle walls (44, 46). Stock from each tube (26) is directed radially toward the centerline along flow paths (47) of equal length. Trailing vanes (68) may be positioned between the rows of tubes (26) so that each flow experiences almost identical flow boundary conditions as it moves towards the nozzle outlet (48), hence contributing to more uniform fiber orientation in the resultant paper web (51).</p> |
