Patent ID: 6086716
Filing Date: 2000-07-11
Classification: D21D,D21F,D21G,Y10S

Abstract:
A method of controlling the formation of a sheet of wet stock comprising fibers wherein the wet stock is formed on a water permeable moving wire of a de-watering machine that has means for supplying an amount of pulp from at least one source, means for adding an amount of non-fibrous additives to the wet stocks, a refiner that subjects the fibers to mechanical action, said refiner being subject to a variable load, and a headbox having at least one slice, wherein each slice has an aperture through which wet stock is introduced onto the wire, said method comprising the steps of:(a) placing at least two water weight sensors underneath and adjacent to the wire and which are positioned at different locations in the direction of movement of the wire and upstream from a dry line which develops during operation of the machine;(b) operating the machine to form a dried sheet product and measuring the water weights of the sheet of wet stock with the water weight sensors;(c) generating signals that are indicative of the water weight measurements and developing a water weight profile based on the signals;(d) adjusting at least one of said variable load of the refiner, the amount of non-fibrous additives to the wet stock, or the amount of pulp supplied from the at least one source so that the water weight profile matches a preselected water weight profile; and(e) in response to changes in the water weight profile so that it does not match the preselected water weight profile, readjusting at least one of said variable load of the refiner, the amount of non-fibrous additives to the wet stock, or the amount of pulp supplied from the at least one source until the water weight profile again matches the preselected water profile.