Paper making and fiber liberation – Processes and products – Running or indefinite length work forming and/or treating...
Reexamination Certificate
1999-09-03
2002-10-08
Hastings, Karen M. (Department: 1731)
Paper making and fiber liberation
Processes and products
Running or indefinite length work forming and/or treating...
C162S358300, C162S360200, C162S210000
Reexamination Certificate
active
06461478
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a pressing device of a paper and/or paperboard machine for the treatment of a fibrous material web which is formed on a band screen and passes together with the band screen around a suitable open roll provided with recesses for receiving water pressed out of the fibrous web and forming a first nip with a counter-surface.
2. Description of Background and Relevant Information
A pressing arrangement of this kind is known from DE 43 01 751, the counter-surface associated with the open roll is formed by a cylindrical press roll with a rigid roll jacket and a smooth surface. The fibrous material web once separated from the band screen is transferred to the smooth surface of the press roll and is guided through a nip which is formed between this press roll and a pressing shoe roll associated with it. A notable dewatering thus arises in the nip formed between the press roll and the pressing shoe roll.
SUMMARY OF THE INVENTION
The invention provides a pressing device of the initially named kind which is of simple layout and kept compact, which a high dry content is obtained with the dewatering of the fibrous material web.
The invention provides for a pressing device for treating a fibrous material web including a band screen for carrying the material web which is formed upon it, an open roll comprising recesses for receiving water pressed out of the material web, a first nip extended in a web running direction being formed between the open roll and a counter-surface comprising a pressing shoe unit, at least one of the open roll and a suction device being provided to suction the material web on the band screen, an open roll felt belt being guided over the open roll and a pressing shoe felt belt being guided over the pressing shoe unit, a second nip arranged downstream the first nip, and another felt belt arranged to travel through the second nip with the material web, wherein the pressing shoe felt belt is separated from the material web while the material web and the band screen is suctioned, and wherein the material web is removed from the band screen between the first and second nips by one of a smooth belt and a smooth roll.
The pressing shoe unit associated with the open roll may be a shoe pressing roll. The open roll may comprise a surface having at least one of grooves and blind bores, said open roll further comprising a non-permeable press roll jacket lying beneath the surface. The open roll may be a suction roll and may include a roll jacket provided with a plurality of radial bores which are not through-bores, wherein the open roll is internally suctioned. The device may further comprise a gutter adapted to capture led-away spun-off water, wherein the open roll is at least partly surrounded by the gutter. The open roll may be a roll tube having a plurality of radial bores which are not through-bores, and wherein the open roll is externally suctioned. The device may further comprise an outer suction box which surrounds a portion of the open roll but which is not in contact with the open roll felt belt that is guided over the open roll. The suction box may comprise an end section having a suction opening adjacent the open roll, and wherein the end section is arranged to be substantially parallel to a pressing plane, wherein the open roll projects at least partly through the suction opening into the end section, wherein at least substantially an entire part of the open roll located outside of the suction box is surrounded by the open roll felt belt, and wherein the open roll felt belt is supported by an outer surface of the end section which is located adjacent to but not in contact with the open roll. The open roll felt belt may be guided symmetrically to a pressing plane of the first nip about the open roll and about the end section of the suction box. The band screen and the fibrous web may be guided away from the open roll at an angle of at least 2° relative to the open roll felt belt.
The invention also provides for a pressing device for treating a fibrous material web comprising a band screen for carrying the material web which is formed upon it, an open roll comprising recesses for receiving water pressed out of the material web, a first nip extended in a web running direction being formed between the open roll and a counter-surface comprising a pressing shoe unit, at least one of the open roll and a suction device being provided to suction the material web on the band screen, an open roll felt belt being guided over the open roll and a pressing shoe felt belt being guided over the pressing shoe unit, the pressing shoe felt belt and the material web being separated from each other after the material web is suctioned, the band screen and the fibrous web being guided away from the open roll at an angle of at least 2° relative to the open roll felt belt, and a separating suction device provided adjacent the band screen and positioned on the side of the open roll where the open roll felt belt separates from the band screen, wherein the separating suction device applies a vacuum suction to the fibrous web in order to dewater the fibrous web together with the band screen, and wherein the separating suction device leads away spun-off water originating from a wedge space defined by the position where the open roll felt belt and band screen separate, such that the separating suction device utilizes a front edge which acts as a deflector strip and extends into the wedge space between the band screen and the open roll felt belt.
The separating suction device may further comprise a gutter located transversely to the web running direction for receiving and leading away the spun-off water which is picked up ahead of the deflector strip of the suction separating device. The shoe pressing roll may comprise a flexible pressing jacket having an outer surface having recesses for receiving pressed-out water from the fibrous web, thereby facilitating even dewatering of the fibrous material web at the first nip, wherein even dewatering results on both sides of the fibrous web when the first nip comprises: the jacket surface; a water permeable felt belt; a water permeable band screen; a water permeable open roll felt belt; and the roll surface. The shoe pressing roll may be at least partly surrounded by a gutter for capturing and leading away the spun-off water from the recesses of the flexible pressing jacket. The second nip may be formed by a press roll and a counter-surface. The material web may be guided, after leaving the second nip, on the smooth belt to a further process section which is directly without an open web run, wherein the further process section includes a drying cylinder. The second nip may be formed by a pressing shoe arrangement which is extended in the web running direction. The pressing shoe arrangement may comprise a shoe press roll and a counter-surface. At least one of the press roll and the counter-surface may comprise a roll jacket which is supported by at least one support element against the other of the at least one of the press roll and the counter-surface. The press roll and the counter-surface may both comprise pressing shoe rolls with flexible pressing jackets having substantially planar pressing surfaces. The smooth roll may comprise a flexible pressing jacket adapted to directly remove the fibrous material web from the band screen, and adapted to supply the material web directly to the second nip, wherein the second nip is formed by a pressing shoe roll and a counter-roll, and the other felt belt is wrapped around the counter roll. The flexible pressing jacket of the shoe pressing roll may transfer the fibrous material web adhering to it to a further process section, after leaving the second nip, directly without an open web run. The second nip may comprise a pressing shoe roll having a rigid smooth jacket such that the pressing shoe roll removes the fibrous material web directly from the band screen without the participation of any belts, and such that the pressing shoe roll supp
Greenblum & Bernstein P.L.C.
Hastings Karen M.
Voith Sulzer Papiertechnik Patent GmbH
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