Modified spiral seam arrangement

Details Modified spiral seam arrangement Modified spiral seam arrangement

1999-10-21

2001-06-05

Hess, Douglas (Department: 2167)

Conveyors: power-driven

Conveyor section

Endless conveyor

Reexamination Certificate

active

06241081

ABSTRACT:

This invention relates to a modified spiral seam arrangement.
Spiral seams are used for example to connect the ends of fabrics to form endless belts for use in paper machine clothing, especially press felt base cloths or dryer fabrics.
In a spiral seam, the ends of a fabric are provided at each edge to be formed with a loop structure capable of interdigitating with a corresponding loop structure on the opposite edge, and the seam is usually secured by means of a pintle wire or rod extending axially through the interdigitated loops. Conveniently, the loops are provided by means of a pair of, preferably flattened, helical coils, each formed from a single continuous metal wire, plastic coated wire, or suitable plastic monofilament. The helical coils are woven into the fabric, or otherwise secured depending upon the nature of the substrate. One side of the spiral is substantially flatter than the other so that the loops are substantially D shaped, the flatter sides being directed towards the paper supporting surface of the fabric in plan view, from the more curved side, each loop of the spiral has an N-shape.
Machine direction (MD) warp yarns are woven in repeat groups of four to each turn of the helical coil. Alternate yarns run short, and the remaining spaced yarns extend into the fringed area and are looped around the leg of the coil adjacent the seam, and a return portion of each is back woven into the fabric in the space made available by the yarns which have run short to in effect provide a continuous warp path.
The weave pattern is such that one of the MD yarns forms a “long”fabric loop, floated over at least the last cross machine weft yarn, and the other a “short”fabric loop coming from below the last weft yarn or floated over fewer yarns than the “long” fabric loop. In the known fabric seam the “short” fabric loop lies between the diagonal and the left hand vertical limb of the N-shape of the spiral coil loop. In this arrangement the “short” fabric loop distorts the coil loop to such an extent that part of the seam moves proud of the belt. This results in undesirable marking of the paper which is being manufactured on the belt.
According to the present invention there is provided a seam arrangement for connecting the ends of a fabric so as to form an endless belt, the seam arrangement comprising a first coil provided at one of said ends of the fabric and a second coil provided at the other of said ends of the fabric, wherein the two coils are operable to be interdigitated and secured together by means of a pintle wire which may be passed through the interdigitated coil loops, and wherein two machine direction yarns of the fabric are passed through each loop of a coil so as to secure the coil to the fabric edge, the machine direction yarns associated with each coil loop providing a “long” fabric loop and a “short” fabric loop, characterised in that each coil loop notionally forms an N-shape with the top of the N-shape being provided by the free ends of the coil loop which are remote from the fabric end to which that coil loop is secured, and in that the “short” fabric loop lies between the “lon” fabric loop and the right hand limb of the N-shape of the spiral coil loop.
Space for back-weaving the MD yarns is created by terminating selected MD yarns short of the edge region, at a joining point, and the return portions back woven to the joining point so that there is no perceptible break in the weave. The MD yarns would preferably be warp yarns.
It has been found that an arrangement of this kind allows the spiral coil to be seated closer into the plane of the fabric, so that the coil stands less proud and thus reduces the extent or depth of any embossing or marking inflicted by the coil on paper which is supported on the fabric and the less proud configuration of the seam makes it less prone to wear.


REFERENCES:
patent: 3436041 (1969-04-01), Haller
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patent: 5065860 (1991-11-01), Faulkner
patent: 5275858 (1994-01-01), Hock
patent: 5405669 (1995-04-01), Lidar
patent: 5908106 (1999-06-01), Krueger
patent: 12 51 105 (1967-09-01), None
patent: 0 275 656 (1988-07-01), None
patent: 0 364 066 (1990-04-01), None

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