Method and apparatus for forming paper
OwnerErkki O. Seppaneninventor
Life of this patent
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Abstract
The wet end of a fourdrinier paper machine includes a transversely disposed roll beneath the wire. The roll is shaped and mounted for rotation at a speed which is different from the speed of the wire to create pulses of negative pressure beneath the wire for drawing liquid from the web of fibers formed thereon. Also disclosed is a fin apparatus transversely disposed beneath the wire to create a wave of positive pressure thereunder to urge the formed web off of the wire.
Claims16
In an apparatus for forming a continuous fibrous web from an aqueous suspension of fibers deposited on the outer surface of a moving foraminous base conveyor having opposed inner and outer surfaces:
- a substantially cylindrical roll having an outer surface defining alternating raised and channel portions parallely extending over said outer roll surface in a generally axial direction, said roll being mounted contiguous to the inner surface of said conveyor and extending thereacross transversely of the direction of conveyor travel but spaced therefrom an amount such that during operation of said apparatus a cushion of liquid removed from said fiber suspension is interposed between the inner surface of said conveyor and the outer surface of said roll so that during such operation said conveyor inner surface is spaced from said roll outer surface and is supported by said cushion of liquid;
- and
- drive means for rotating said roll so that the speed of the outermost portion of said outer surface of said roll does not equal the speed of said conveyor so that as a roll raised portion passed through a location closest to the inner surface of said conveyor, areas of oppositely directed pressure pulses are applied to the conveyor inner surface immediately upstream and downstream from said location respectively, so that at least some liquid is removed from said fiber suspension in the area of a negative pressure pulse to form said liquid cushion whereupon the liquid is carried on said roll surface and a portion thereof reintroduced into the fiber suspension in the area of a positive pressure pulse at high velocity to agitate said suspension and orient a portion of the fibers thereof in a direction substantially perpendicular to the direction of travel of said conveyor.
A process for forming a continuous fibrous web from an aqueous suspension of fibers deposited on the outer surface of a moving foraminous conveyor having opposed inner and outer surfaces comprising the steps of:
- rotatably mounting a substantially cylindrical roll having an outer surface defining generally axially extending alternating raised and channel portions contiguous to the inner surface of said conveyor so that it extends transversely thereacross in the direction of conveyor travel;
- applying oppositely directed pressure pulses to the inner surface of said conveyor at areas immediately upstream and downstream from a particular location, respectively, by rotating said roll while said suspension carrying conveyor is being moved at a rate such that the speed of the outermost portion of the outer surface of said roll does not equal the speed of the conveyor whereupon at least some liquid is removed from the suspension in the area of a negative pressure pulse to form a liquid cushion interposed between said roll and said conveyor inner surface to support the latter and so that the roll outer surface is spaced from said conveyor inner surface of said cushion of liquid and whereupon at least some liquid is reintroduced from the liquid cushion into the suspension in the area of said positive pressure pulses at high velocity to agitate said suspension and orient a portion of the fibers thereof in a direction substantially perpendicular to the direction of travel of said conveyor.
Dependencies are inferred from the claim text.