Patent ID: 7578906

Claim:
A headbox and stock delivery system for a papermaking machine, comprising: (a) a radial stock distributor including a radial manifold having connector hoses extending therefrom; (b) a plurality of connector pipes to which the connector hoses from the radial manifold are connected, each of the connector pipes having a step expansion followed by a circular cross-section which tapers to a generally rectangular cross-sectional shape and which are located at regular intervals in a cross-machine direction (CD) across an inlet duct; (c) a stock dilution assembly which is connected to and receives the stock from the inlet duct, the stock dilution assembly including a plurality of stock feed pipes that extend from the inlet duct, and a respective dilution feed pipe in communication with and adapted to convey fluid from a source of lower consistency fluid to each of the individual stock feed pipes, a flow of fluid from each of the dilution feed pipes being controlled by a respective valve associated with each of the feed pipes, the plurality of stock feed pipes being adapted to receive the stock from the inlet duct and the fluid from the respective ones of the dilution feed pipes to adjust a basis weight consistency of the stock; (d) a headbox, including a stilling chamber, a tube bank, a nozzle with turbulence vanes to control stock turbulence and minimize streaks, and slice adjustment systems for allowing movement of a headbox slice in both horizontal and vertical directions: (i) the stilling chamber comprises an open chamber located downstream of and in communication with the stock dilution assembly and upstream of in communication with the tube bank and through which the dilution profiled stock passes towards the tube bank; (ii) the tube bank comprises of a plurality of shaped tubes through which the stock passes as it progresses downstream towards the nozzle and the vanes to control turbulence, the tubes being mounted at regular intervals in at least one row and shaped so that a cross-sectional profile of the tubes transitions from a generally circular shape at an upstream end to a generally rectilinear shape at a downstream end, and a cross-sectional area of each of the tubes does not diminish in the downstream direction; (iii) the turbulence vanes are located downstream of the tube bank and are positioned so that stock exiting each of the tubes in the tube bank passes either over or under at least one of the vanes; and (iv) the slice adjustment systems comprise actuators connected to at least one moveable wall that defines the nozzle to adjust a position of the wall so that an opening of the nozzle is adjustable.