Paper making and fiber liberation – Apparatus – Running or indefinite length product forming and/or treating...
Reexamination Certificate
2002-12-02
2004-12-07
Griffin, Steven P. (Department: 1731)
Paper making and fiber liberation
Apparatus
Running or indefinite length product forming and/or treating...
C162S348000, C162S900000, C162S902000, C162S903000, C139S3830AA, C139S42500R, C442S206000, C442S207000, C428S147000, C428S175000, C428S196000
Reexamination Certificate
active
06827821
ABSTRACT:
FIELD OF INVENTION
This invention relates generally to improved, high permeability, multi-layer woven members for use in papermaking machines. In the preferred embodiments, the members are employed to convey fibrous webs through the dryer section of a papermaking machine. Most preferably the woven members of this invention are carriers, or base fabrics for a resinous, embossing layer cast thereon. In accordance with this invention the woven members employ a unique woven structure to achieve numerous benefits.
BACKGROUND OF THE INVENTION
Multi-layer fabrics are widely known in the papermaking art and are employed in various sections of a papermaking machine. One such multi-layer structure, which preferably is employed in the dryer section of a papermaking machine, is disclosed in Gaisser U.S. Pat. No. 5,114,777. The woven fabric disclosed in Gaisser is a two layer structure including pairs of vertically stacked warp yarns that are spaced apart from each other in the cross-machine-direction and are held together in their vertically stacked relationship by a plurality of single weft yarns spaced along the machine direction of the fabric. Although this fabric has been used commercially in dryer fabrics, improvements are desired in material costs, stability, seam strength and drainage or water extraction from fibrous webs without retention of excess water in the fabric.
Other multilayer papermaking fabrics employing warp binder yarns and being usable in various sections of a papermaking machine are disclosed in the prior art. For example, Stelljes, Jr. et al. U.S. Pat. No. 5,840,411 discloses a number of different embodiments of two-layer fabrics wherein each layer includes interwoven weft and warp yarns. These layers are connected together by tie warns, which can be separate warp or weft yarns that are independent from the weave pattern in either layer, or warp or weft yarns that also contribute to the weave pattern in one or both of the layers. Also, these tie yarns are described as possibly being of a reduced diameter to minimize blockage of open areas through the fabric. The structures disclosed in this patent employ two distinct layers, each including interwoven single warp and single weft yarns and are not directed to structures employing a plurality of paired warp yarns in the weave construction.
U.S. Pat. No. 4,995,529, issued to Kositzke, discloses a multilayer film including upper and lower, self-sustaining layers, each including interwoven machine direction and cross machine direction yarns. Although this patent discloses the vertical aligning of machine direction and cross machine direction yarns in each layer, it does not relate in any way to structures including paired machine direction yarns in either layer.
U.S. Pat. No. 5,454,405, issued to Hawes, discloses a triple layer papermaking fabric including top and bottom weft yarn layers interconnected by top warp yarns that form part of a warp yarn system with underlying warp yarns. The underlying warp yarns are not employed to bind the top and bottom weft yarn layers together. This patent does not disclose a fabric employing paired warp yarns transversely aligned in a single layer.
U.S. Pat. No. 5,219,004, issued to Chiu, discloses multilayer structures employing bottom warp binder yarns. In one disclosed embodiment these bottom warp yarns are included in pairs, with each pair being located in a region underlying the open area between two, single top warp yarns. These disclosed fabrics are described as being forming fabrics usable in the wet end of a papermaking machine and are neither designed nor intended to be employed as a dryer fabric in a dryer section of a papermaking a machine. In particular, the fabrics disclosed in the Chiu '004 patent have a substantially lower open area than is desired or needed in dryer fabrics of papermaking machines. In fact, the top ply or layer of the Chiu structure preferably has twice as many shute yarns as in the bottom side, with the shute yarns on the bottom side underlying the open area between the shute yarns in the top ply. This impedes the flow of water through the fabric, and would be undesirable for use in dryer fabrics; particularly through air dryer (TAD) fabrics.
Other types of fabrics employing partner yarns are disclosed in Fitzka et al. U.S. Pat. No. 5,092,372. In these fabrics extra partner yarns are added to a top ply to vary the number of fiber supporting points in the fabric.
Other multi-layer fabrics for use in papermaking machines are disclosed in U.S. Pat. No. 4,314,589 (Buchanan et al.); U.S. Pat. No. 4,501,303 (Osterberg); U.S. Pat. No. 4,705,601 (Chiu); U.S. Pat. No. 4,729,412 (Bugge); U.S. Pat. No. 4,832,090 (Krenkel et al.); U.S. Pat. No. 4,945,952 (Vohringer); U.S. Pat. No. 5,054,525 (Vohringer); U.S. Pat. No. 5,151,316 (Durkin et al.) and U.S. Pat. No. 5,152,326 (Vohringer).
Applicants believe that a need exists for improved, high permeability, multi-layer woven members in papermaking machines; preferably in dryer fabrics, and more particularly in through air dryer (TAD) fabrics, which have excellent seam strength, excellent stability, high drainage and lower water retention properties than prior art dryer fabric structures and that are capable of supporting, or receiving a cast, resinous, embossing layer employing less resinous material than prior art structures. It is to such woven members and composite dryer fabrics employing same that the present invention is directed.
SUMMARY OF THE INVENTION
The above and other objects of this invention are achieved in a multi-layer woven fabric, which, when flat woven, includes a top layer with a self-sustaining weave construction including top warp yarns extending in the machine direction of fabric movement through a section of a papermaking machine interwoven with top weft or shute yarns extending in the cross-machine-direction of a papermaking machine, most preferably but not necessarily in a plain weave pattern for engaging and/or supporting a fibrous web in a papermaking machine. A bottom layer includes bottom pairs of warp yarns extending in the machine direction of fabric movement through a section of a papermaking machine, and bottom weft, or shute yarns extending in a transverse, or cross-machine-direction substantially normal to said machine direction.
Most preferably, the fabrics of this invention are formed in a flat weaving process, resulting in the warp yarns being disposed in the machine direction of fabric movement through a section of a papermaking machine and the weft yarns being disposed transversely to the warp yarns, i.e., in the cross-machine-direction of the papermaking machine. Although it may be difficult to form the fabrics of this invention in an endless weaving process, if such a process is employed than the weft yarns will be disposed in the machine direction of fabric movement through a section of a papermaking machine and the warp yarns will be disposed transversely to the weft yarns, i.e., in the cross-machine-direction of the papermaking machine. In accordance with the broadest aspects of this invention the fabrics may be formed by either a flat weaving process or an endless weaving process; although the flat weaving process is preferred.
Reference throughout this application, including the claims, to fabrics having yarns being in the “machine direction” refers to the direction of such yarns on a papermaking machine; not on a loom employed to manufacture the fabrics. Similarly, reference throughout this application to fabrics having yarns being in the “cross-machine-direction” refers to the direction of such yarns on a papermaking machine; not on a loom employed to manufacture the fabrics.
For ease of discussion, throughout the remainder of this application flat woven fabrics of this invention will be described, wherein the first and second layers each include warp yarns extending in the machine direction. However, as stated above, in endless woven fabrics of this invention weft yarns will extend in the machine direction.
In preferred embodiments of the invention the bottom wa
Brewster James Loy
Hay Stewart Lister
Herman Jeffrey Bruce
Thomas John M.
Caesar Rivise Bernstein Cohen & Pokotilow Ltd.
Griffin Steven P.
Hug Eric
Voith Fabrics Heidenheim GmbH & Co. KG
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