GB1099476A - Headbox - Google Patents

Abstract

1,099,476. Paper-making. BELOIT CORPORATION. March 30, 1965 [April 3, 1964], No. 13393/65. Headings D2A and D2B. In a headbox of a paper-making machine the stock is urged through a perforated curved plate 23 by bars 19-22 of aerofoil crosssection. Each bar 19-22 is supported by a series of arms 15-18 on rotor 14. The heading and trailing edges of the bars 19-22 create respectively positive and negative pressure waves which urge the stock through the perforations-which may be slots or holes- and then suck back any fibre lumps clogging the perforations. These lumps are removed through exit A. The headbox may be of the pressurized type and have flow evener roll 27, water showers 8a, and an adjustable slice 3a. The headbox may take various forms, Figs. 2-8 (not shown),-for example, these may be eight bars of aerofoil cross-section; the stock inlet Z may lead directly into the cylindrical space defined by walls 23, 37; the stock inlet may be formed by two co-axial pipes extending in the cross-machine direction, the stock flowing from the inner pipe through perforations into the annular space between the pipes and thence into the headbox proper; or shaft 13 may be hollow and both shaft 13 and rotor 14 be perforated so that the stock is fed into shaft 13 and through the perforations into the cylindrical space. Plate 23 may be vibrated. In one embodiment Figs. 5 and 6 (not shown) a second headbox is placed upside down underneath the first headbox with the two stock streams converging but not intermixing adjacent a common slice. Thus a "twoply" sheet may be obtained. The stock in the upper headbox may have shorter fibres, lower consistency, or be of higher grade than the stock in the lower headbox. The upper stream may flow at less than the wire speed, or may have some filler with the lower stream being without additive.