GB1223709A - Improvements in or relating to headboxes - Google Patents

Abstract

1,223,709. Headbox. BLACK CLAWSON CO. 13 June, 1968 [14 June, 1967], No. 28261/ 68. Heading D2A. A headbox for a papermaking machine comprises a chamber extending across the. machine above the forming member, a slice assembly having upper and lower lips defining the stock discharge outlet, a tube assembly including a plurality of separate and generally parallel passageways of relatively small individual cross-section compared with the total cross-sectional area open to stock flow through the chamber, positioned between said chamber and said slice assembly, means rigidly securing the passageways together to impart a beam-like structure to the tube assembly, the chamber and the slice being connected to opposite ends of the passageways, which open into the chamber and the slice assembly. This headbox may be used as a secondary headbox, supplying a second layer of stock to a wet web. The tube assembly may be formed of initially separate tubes, either secured together for at least the major portions of their lengths, or secured together, at either end of the tubes by plates, which are secured to the chamber and slice assembly, respectively. A supply header may have a wall in common with the chamber, and with the tube assembly the wall between the chamber and the header being perforated to allow flow of stock, and the header and tube assembly thereby support each other and the rest of the headbox. The tube assembly may be straight or curved. In all the embodiments described, a perforated roll is placed in the chamber adjacent to the tube inlets.