Textiles: weaving – Fabrics – Drier felts
Patent
1993-06-18
1995-12-19
Falik, Andrew M.
Textiles: weaving
Fabrics
Drier felts
428193, 428234, D03D 1300
Patent
active
054761239
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention generally relates to a woven fabric which is designed for use in a papermaking, cellulose or board manufacturing machine and which along each one of two end edges has a plurality of loops to be included in a loop seam to form an endless woven fabric. The invention also relates to a method of manufacturing such a fabric.
More specifically, the invention provides an improvement of such a loop seam by conforming it to the rest of the woven fabric, so as to avoid markings in a paper web at the loop seam.
The woven fabric according to the invention is particularly useful, but by no means exclusively so, as a base fabric in a press felt for the press section of a papermaking machine. Press felts are manufactured either with or without a seam. Present-day Joining techniques rely almost exclusively on a so-called loop seam, where two fabric edges (not necessarily of the same fabric) to be joined together each have one row of seam loops. These loops are inclined or orthogonal to the principal plane of the fabric. When joining together the two fabric edges, the loops on one edge are inserted between the loops of the other edge, whereupon at least one separate seam thread is inserted in the interlaced seam loops to lock them to one another.
Such a loop seam is however not entirely satisfactory for several reasons, which will be given hereinafter with reference to FIGS. 1-7 illustrating a woven fabric of the prior art, a method of manufacturing a fabric, as well as the shortcomings of this prior art.
FIG. 1 is a vertical cross-section taken parallel to warp threads in an embodiment of a known double-layered woven fabric, and FIG. 2 is a section taken along the line II--II in FIG. 1. The woven fabric in FIG. 1 has warp threads V1, V2, V3, V4 extended in the plane of the drawing sheet, and weft threads 1-8 extended orthogonally to the plane of the drawing sheet and distributed in two layers L1, L2. The warp threads V1-V4 are crimped around the relatively straight weft threads 1-8, each warp thread, such as the warp thread V1, cyclically following the pattern "over.fwdarw.between.fwdarw.under.increment.between" with respect to the two layers L1, L2 of weft threads (see also FIG. 8 to the left of plane A).
FIG. 3 schematically shows a method of weaving the double-layered fabric in FIGS. 1 and 2 with a so-called round weaving technique, where seam loops 11, 11' of the above-mentioned type are woven simultaneously with the fabric. The weft in FIG. 3 is woven in the order 1.fwdarw.2.fwdarw.2'.fwdarw.1'. The weft threads 1 and 2 in the so-called top cloth form the seam loop 11 around a seam thread 10 parallel to the warp threads. The weft threads 1' and 2' in the so-called bottom cloth form the seam loop 11' around the same seam thread 10. At the transition to the left in FIG. 3 between the top cloth and the bottom cloth, the weft forms an irregularity at the loom edge.
FIG. 4 schematically shows on a larger scale the seam loop 11 with the seam thread 10 removed, and the four warp threads V1-V4 located closest to the loop 11.
FIG. 5 schematically shows a finished loop seam between the end edges of a double-layered woven fabric according to FIGS. 1-4. As described above, the seam loops 11, 11' are formed by weaving the weft threads 1-8 around the seam thread 10. The seam thread 10 used during the weaving procedure and hereinafter referred to as "weaving seam thread", may typically have a diameter of 1.2-1.7 mm. The weaving seam thread is removed from the seam loops before the woven fabric is mounted in the papermaking machine. For the final joining of the seam in the papermaking machine, use is however normally made of a seam thread 10 of slightly smaller diameter, e.g. 0.7 mm, to enable it to be passed easily through the loops. The area around the final loop seam (FIG. 5) will therefore have a larger void as compared with the seam formed directly in the loom (FIG. 3). This increased void is illustrated in FIG. 5, where the seam zone consists of regions O1, O2, O1, where O2 is
REFERENCES:
patent: 3815645 (1974-06-01), Codorniu
patent: 4182381 (1980-01-01), Gisbourne
patent: 4824525 (1989-04-01), Penven
patent: 4863786 (1989-09-01), Green et al.
patent: 4896702 (1990-01-01), Crook
Falik Andrew M.
Nordiskafilt AB
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