Paper making and fiber liberation – Apparatus – Running or indefinite length product forming and/or treating...
Reexamination Certificate
1999-09-30
2001-09-11
Chin, Peter (Department: 1731)
Paper making and fiber liberation
Apparatus
Running or indefinite length product forming and/or treating...
C162S358100
Reexamination Certificate
active
06287427
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pressing apparatus, and more particularly, to a pressing apparatus having a plurality of rollers forming a chamber.
2. Description of the Related Art
For many years attempts have been made to use external air pressure to force water out of a paper web. Rather than compress a sheet at a press nip to the point where hydraulic pressure drives water out, as is the case in normal wet pressing, it was reasoned that more water could be removed, and sheet bulk could be maintained, if air pressure could be applied to supplement roller nip generated hydraulic pressures. One such attempt involves providing a multi-roller structure forming a closed chamber, wherein air is circulated through the chamber to convect moisture out of the paper web.
Providing efficient sealing of a multi-roller chamber can be problematic. It is known to form a roller assembly wherein rubber rollers are positioned to interact with solid surface rollers. One potential problem in trying to seal such a chamber is that considerable loading to the roller structure may required to maintain the seal between the rollers. Accordingly, a robust frame is required to confine the roller structure. Another potential problem in trying to seal such a chamber is that any cuts into the rubber surface would tend to render the entire roller unusable.
Accordingly, a need exists for an improved pressing apparatus which provides efficient roller-to-roller sealing at the roller nips, and includes a roller sealing sleeve which is replaceable.
SUMMARY OF THE INVENTION
The present invention provides a pressing apparatus which provides efficient roller-to-roller sealing at the roller nips, and in preferred embodiments, includes a roller sealing sleeve which is replaceable.
One aspect of the invention is directed to a roller unit for a pressing apparatus for processing a continuous web. The roller unit includes a roller having a first circular end, a second circular end and a cylindrical middle surface. An elastic sealing sleeve having a plurality of pressurizable fluid cavities is positioned over the cylindrical middle surface of the roller.
In another aspect of the invention, a first end seal is attached to the first circular end and a second end seal is attached to the second circular end, wherein each of said first end seal and said second end seal include a plurality of pressurizable fluid cavities.
Still another aspect of the invention is an apparatus for processing a continuous web. A plurality of rollers are arranged for cooperative rotation, each of the plurality of rollers having a first circular end, a second circular end and a cylindrical middle surface. The plurality of rollers define a corresponding plurality of nips. The plurality of rollers include a first main roller, a second main roller, a first cap roller and a second cap roller, and wherein an axial extent of each of the first and second main rollers and the first and second cap rollers together are arranged in parallel. The first and second cap rollers serve to seal against the first and second main rollers at the roller nips. A first sealing panel and a second sealing panel engage the first and second circular ends of each of the plurality of rollers, the first and second sealing panels and said plurality of rollers define at least one chamber. A first elastic sealing sleeve having a plurality of pressurized fluid cavities is positioned over the cylindrical middle surface of the first cap roller. A second elastic sealing sleeve having a plurality of pressurized fluid cavities is positioned over the cylindrical middle surface of the second cap roller.
An advantage of the present invention is that the elastic sealing sleeve, which has a plurality of pressurizable fluid cavities, is elastically deformable to provide effective chamber sealing at the roller nips of the pressing apparatus.
Another advantage of the present invention is that the elastic sealing sleeve is replaceable.
Another advantage of the invention is that the roller end seals, which has a plurality of pressurizable fluid cavities, are elastically deformable to provide effective sealing with the sealing panels of the pressing apparatus.
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TAPPI, Characterization of Wet Felts, TIP 0404-20, 1976, pp 1-3.
Joseph R. Pounder, Elementary Mathematical Models of Displacement Pressing, TAPPI Journal, Feb., 1987, pp 97-100.
Wlodzimierz Kawka and Edward Szwarcsztajn, Some Results of Investigations on the Equipment for Intensive Dewatering and Drying of Porous Papers, Technical University of Lodz/Poland, Paper No. 31, pp 153-169.
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Chin Peter
Hug Eric
Taylor & Aust P.C.
Voith Sulzer Papiertechnik Patent GmbH
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