Textiles: weaving – Fabrics – Drier felts
Reexamination Certificate
1999-12-13
2001-05-08
Falik, Andy (Department: 3765)
Textiles: weaving
Fabrics
Drier felts
C442S208000
Reexamination Certificate
active
06227256
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a dual layer papermaking fabric which provides even drainage throughout and in which both the paper support surface and the machine contact surface are weft dominant surfaces.
Normally, dual layer papermaking fabrics are woven with a single set of warp threads, upper layer weft threads and lower layer weft threads. Normally, the number of upper layer weft threads is twice that of the lower layer weft threads. It is also desirable to have long weft floats on the paper support surface to provide a smooth surface with adequate permeability. The machine contact surface also preferably comprises long weft floats also for adequate permeability and further for protecting the warp threads against wear through excessive contact with the machine rolls.
Papermaking fabrics developed with these features in mind are disclosed in U.S. Pat. Nos. 4,739,803; 4,709,732; 5,025,839; 5,487,414; and 5,555,917.
The instant invention has for its object, a papermaking fabric having a paper support surface which is smooth so as to reduce fabric marking on the paper to a minimum.
Another object of the invention is a papermaking fabric having a paper support surface having machine direction crossover forming balanced twill lines which provide a minimum number of uniform markings on the paper.
Another object of the invention is providing a papermaking fabric having a minimum number of the warp threads exposed on the outer fabric surfaces providing increased wearability and improved uniformity.
Another object of the invention is a papermaking fabric which maintains even drainage during use.
Another object of the invention is a papermaking fabric having stabilized machine contact surface floats.
Another object of the invention is a papermaking fabric having stabilized support surface floats.
Another object of the invention is a papermaking fabric in which the warp crossovers on the paper support surface and the warp cross-unders on the machine contact surface form diagonal twill lines across each fabric surface.
Another object of the invention is a multi-layer papermaking fabric in which the weaves of each fabric layer are balanced.
SUMMARY OF THE INVENTION
The instant invention is directed to a multi-layer papermaking fabric which utilizes a single set of MD (machine direction) yarns. The fabric includes a lower CMD (cross machine direction) layer having a selected number of yarns per inch and an upper CMD layer having a selected number of yarns per inch which are at least twice that of the lower CMD layer. A system of MD yarns are interwoven with the upper and lower CMD yarns in a repeated weave pattern. Preferably the number of upper CMD yarns is twice the number of lower CMD yarns.
The weave pattern requires that each MD yarn weave to cross-under an even number of lower CMD yarns and to crossover an uneven number of upper CMD yarns with the number of upper CMD yarn crossovers being three fifths of the CMD yarn crossovers and cross-unders. The MD yarn and the CMD yarn crossovers and cross-unders are arranged in twill arrays diagonally across the width of the weave pattern.
Selected of the CMD yarn floats of the upper surface are tied in with a single crossover of a MD yarn at each end within the weave pattern while other of the CMD yarn floats are tied in with a single crossover of a MD yarn only at one end, within the weave pattern. These other of the CMD yarn floats are arranged between the selected CMD yarn floats throughout the weave pattern.
It is preferred that the uneven number of crossovers of each MD yarn comprises three. Also, it is preferred that each of these crossovers cross over only one CMD yarn. It is also preferred that certain of these crossovers of each of the MD yarns are separated by at least ten CMD yarns while others of these crossovers are separated by as few as two of the CMD yarns per weave pattern repeat.
On the machine or lower surface, each of the CMD yarns forms only one float which passes beneath a majority of the MD yarns for each weave pattern repeat. These lower surface CMD floats are tied in with a plurality of consecutive MD yarns which successively pass under, over and under each CMD yarn forming a tie end point at one end of the CMD float. The tie end points form twill lines diagonally across the lower surface of the weave pattern.
The weave requires selected of the upper CMD yarns to cross under selected MD yarns and form a cross-under which appears on the lower surface. The weave does not allow a lower CMD yarn to appear on the upper surface.
The weave pattern, which produces a CMD yarn dominated support and machine surfaces utilizes sixteen MD yarns per weave pattern repeat. There are forty-eight CMD yarns per weave pattern repeat. It is preferred that the CMD yarns are of equal size. The CMD yarns forming the support surface may be of a different diameter than the CMD yarns forming the contact surface. Also, the CMD yarns forming the support surface may be of multiple sizes.
Each of the CMD yarns forming the contact surface is stacked beneath selected of the CMD yarns forming the support surface. These selected CMD yarns are each separated from each other by a single support surface CMD yarn.
REFERENCES:
patent: 4709732 (1987-12-01), Kinnunen
patent: 4739803 (1988-04-01), Borel
patent: 5025839 (1991-06-01), Wright
patent: 5052448 (1991-10-01), Givin
patent: 5054525 (1991-10-01), Vohringer
patent: 5067526 (1991-11-01), Herring
patent: 5487414 (1996-01-01), Kuji et al.
patent: 5544678 (1996-08-01), Barrett
patent: 5555917 (1996-09-01), Quigley
patent: 5694980 (1997-12-01), Quigley
patent: 5713397 (1998-02-01), Quigley
patent: 5988229 (1999-11-01), Quigley
patent: 6148869 (2000-11-01), Quigley
Albany International Corp.
Falik Andy
Pitney Hardin Kipp & Szuch LLP
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