EP1155186B1 - Junction with symmetrical weave for woven band with asymmetric weave - Google Patents

Abstract

A woven strip comprising an asymmetrical weave of weft and warp yarns having symmetrical re-weaving zones extending from opposite ends thereof, in which the end warp yarns form a loop to accommodate a restraining rod. The woven strips provide fabrics for use in paper making machines and have the advantage of avoiding excess pressure during operation of the machine thereby reducing marking of the paper and wearing of the strips.

Description

The invention relates to a woven strip, particularly intended for the paper industry, having an asymmetrical weave made up of weft and warp threads extending between two opposite ends of the bandaged. the warp threads being rewoven. after folding at each end of the strip, with the weft threads on a reweaving area adjacent to said end to form loops. Such a strip is known from document EP-A-0 612 882.

For example for the paper industry, the manufacturing machines in continuous paper generally include three sections respectively, from training. water extraction by pressing and drying the sheet paper.

In the drying section of a papermaking machine, the sheet of paper is applied to a set of heated cylinders. To improve the drying speed of the paper sheet, it is transported on the cylinders heated by woven bands (commonly called dryer), preferably having an asymmetrical weave, comprising generally weft threads having a round section woven with threads chain having a flattened section, these chain wires defining large floats on the right side of the strip which is in contact with the sheet of paper. This type of strip allows a reduction in the marking of the sheet of paper by the chain threads, this in a machine configuration in which the strip is in constant contact with the sheet throughout the course of it in a serpentine shape on two horizontal rows of cylinders.

By the way, in a woven band having an asymmetrical weave constituted by chain wires defining floats on the right side of the band, the neutral plane of the band (the plane of the band which undergoes neither compression, no extension when the strip is bent) is arranged between the median plane and the right side of the strip in the direction of its thickness. The result as the right side of the strip in contact with the sheet of paper moves to a substantially constant speed on the cylinders which has the effect of reduce the tensions in the sheet of paper as well as the risks of abrasion of the strip when the dryness of the sheet of paper becomes important, this in a machine configuration where the strip is in constant contact with the sheet throughout its serpentine path between the top and bottom cylinders of the machine.

Each woven strip is configured endlessly when installed on machine, using, for example, a rigid rod which is passed inside the loops formed at one end of the strip and loops formed at the other end of the strip, the loops of the two ends being meshed together with the others before passing the ring as is well known. But when this band, configured endlessly, is put into service, under the effect of tensions which are exerted on the band during its displacement training, the joining line of the two ends of the strip formed by the rod is propelled from the median plane of the band towards the right side of the strip, the axis of the rod coming to be placed in the neutral plane of the strip. This displacement of the strip joining line in the direction of the thickness of the strip creates an overpressure on the sheet of paper which induces a significant risk of marking the sheet of paper and rapid abrasion of the bandaged. The object of the invention is to remedy these drawbacks.

To this end, the invention relates to a woven band, intended more particularly in the paper industry, having an asymmetrical weave made up by weft threads and warp threads extending between two ends opposite of the strip, the warp threads being rewoven, after folding to each end of the strip, with the weft threads on a reweaving area near said end to form loops, characterized in that each reweaving area has symmetrical weave.

Such a construction makes the joining line of the ends opposite of the strip is no longer subject to displacement in the direction of the thickness of the strip when the latter, configured endlessly, is put under pressure. Indeed, in the areas of weaving of the warp threads, the plane neutral of the band is confused with the median plane of the latter in which extends the joining line of the ends of the strip. In addition, the gradient of the neutral plane of the strip is distributed over the two zones of reweaving of the warp threads and no longer located on the joining line from both ends of the strip.

According to a particular embodiment of the invention, each zone of reweaving with symmetrical weave near one end of the strip can be formed by making the chain wires having reached the end, after folding, instead of adjacent warp threads that were interrupted before the reweaving area.

According to a preferred embodiment of the strip according to the invention, the chain wires are bent orthogonally to the band plane at each end of the latter and the weft threads of the reweaving zones have a diameter smaller than the weft threads of the rest of the strip.

By bending the chain wires orthogonally to the plane of the strip, we reduces the size of the loops in the direction of the weft threads. However, each chain wire after folding at one end of the strip, is rewoven in over-thickness on itself with the weft threads in the reweaving area. But the reduction in the diameter of the weft threads in each reweaving area compensates for the excess thickness of the chain son to maintain a relatively constant thickness of the strip over its entire length. A crepe weft threads, during the high temperature heat setting operation of the weft yarn and warp yarn, will ultimately reduce any difference thick between the reweaving zones and the rest of the strip.

According to another preferred embodiment, the warp threads have a flattened section which reduces the marking of the sheet of paper and the tape permeability.

The invention is now described in more detail with reference to particular embodiments cited by way of nonlimiting example and represented by the accompanying drawings.

FIG. 1 very schematically shows, viewed in longitudinal section, one end of a strip woven to a single plane of weft threads according to the invention.

FIG. 2 very schematically shows, viewed in longitudinal section, one end of a woven strip with two planes of weft threads according to the invention.

Figure 3 shows very schematically, in top view, the loops formed at both ends of a woven strip according to the invention for a joining using two rods.

Figure 4 shows very schematically, in top view, the loops formed at one end of a woven strip according to the invention for a joining using two spirals.

Figures 5 and 6 show very schematically, in top view, the loops formed at one end of a woven strip according to the invention for a joining using a spiral.

FIG. 1 very schematically shows in longitudinal section, the end of a woven strip 10 according to the invention which is intended entirely particularly to a drying section of a machine for manufacturing the paper.

This woven strip includes a single plane of weft threads 11-15, 17-24 of round section and chain wires having here a flattened section and which extend between the two opposite ends of the strip. A single chain wire 16 is illustrated in FIG. 1. On the right side 25 of the strip intended to be in contact with the sheet of paper in the drying section of a papermaking, each chain wire such as 16 defines large floats on the weft threads, here floats covering three consecutive weft threads, for constitute an asymmetrical weave pattern in which the neutral plane PN of the strip is offset from the median plane PM of the strip. More specifically, we see that the warp 16 after each float on the right side 26 of the strip, crosses the weft plane to be woven on the reverse side 26 of the strip bypassing a single weft thread and crossing the weft thread plane again to define another float on the right side of the strip. It is understood that adjacent warp threads in the direction of the weft threads, cross the plane of weft at different levels along the strip as is well known.

At each end of the strip, each chain wire such as 16 is rewoven, after folding, with weft threads 17-24 on a reweaving area near this end but in such a way that this reweaving area has a symmetrical armor in which the neutral plane PN of the strip is confused with the median plane PM of the band. More particularly as visible in Figure 1, we see that the chain wire 16, after folding around the weft thread 17, is rewoven by defining floats on the reverse side 26 of the strip covering three consecutive weft threads such as 19-21. Therefore, each chain thread is rewoven after folding on the reverse side of the strip with a weave pattern to the weave pattern on the right side of the strip. The limit of the reweaving zone with symmetrical weave of the warp threads at one end of the band is indicated by the arrow B while the arrow A indicates the limit of the rest of the band body with asymmetrical weave.

As shown in Figure 1, the chain wire 16 of section flattened is rewoven with weft threads 17-24 in the reweaving area B which have a diameter d smaller than the diameter D of the weft threads 11-15 of the rest A of the strip and the chain wire 16 is rewoven in superposition on itself of it is folded at the end of the strip orthogonally to the plane of the bandaged. During the manufacture of the woven strip according to the invention, it is replaced actually in each reweaving area at the end of the weft thread band having a diameter D by weft threads having a diameter d smaller than so that after reweaving the warp threads on the right side and the face reverse side of the strip, the thickness H 'of the strip in the reweaving zones B is the same as the thickness H of the body A of the strip. In the case of a band woven having only one plane of weft threads, the difference between the diameter of the threads of weft of the body A of the strip and the diameter of the wefts of the zones of reweaving B is twice the thickness of a flattened section wire such as 16. During the reweaving operation of the warp threads, it is brought out the end of these chain threads on the reverse side 26 of the strip at different places along it, depending on the weave pattern defined by the wire chain considered, to have a bending gradient of the reweaving zones.

In FIG. 1, it can be seen that the gradient of the neutral plane PN of the band is spread over a certain length of the strip at the joint of the reweaving B and body A of the strip.

Figure 2 shows a woven strip similar to that of Figure 1 but with two weft planes. We see on this figure the asymmetrical armor of the body A of the strip and the symmetrical weave of the weaving area B of the threads chain such as 16 and the neutral plane layout PN of the band in relation in the midline PM of the band.

As indicated above, each chain wire such as 16 to section flattened is folded at each end of the strip orthogonal to the plane of the strip by forming either a joining loop such as 27, or not joining loop, i.e. by tightening the last weft thread 17 of the end of the strip so as to create a free space between two loops of adjacent junctions formed at this end of the strip. The reduction the density of the loops contributes to facilitate the joining of the two ends of the strip.

FIG. 3 illustrates a first embodiment of loops joining at both ends of a woven strip according to the invention. We see in this figure that a sequence of four sons of chain FC1-FC4 form at one end B (reweaving area B) of the strip respectively a large loop, no loop, a small loop and no loop and that these same wires of chain FC1-FC4 form at the other end B 'of the strip (reweaving zone B ') respectively no loop, a large loop, a small loop and no loop. At each end of the strip, the large loops protrude by compared to small loops. The loops on one end of the strip are meshed with the loops on the other end of the strip. Small curls from the end B of the band define with the large loops of the end B 'of the strip a channel through which a first rod 28 has passed. end B loops of the band define with the small loops of the end B 'of the strip another channel in which a second rod has passed 29. The resistance of the junction zone is in this case comparable to the rest of the tape. The free spaces left by the FC4 chain wire at each end B, B 'of the strip allow the loops formed by the wires FC1, FC2 and FC3 to be less tight. This embodiment of loops at each end of the tape reduces the permeability of the loop area, avoid marking the sheet of paper and get a junction having maximum resistance and not creating excess thickness by compared to the rest of the band. Furthermore, the junction area of the two ends of the band can flex in the plane of the band but without pivoting around one of the rods 28 or 29. Note that if the reweaving is such that the loops formed at the ends of the strip have an identical length, these loops could not mesh with each other due to their density too high and high resistance of the junction could not be obtained.

FIG. 4 illustrates a second embodiment of the loops joining at the two ends of a woven strip according to the invention for a joining of the two ends using two spirals. We see on this figure that a sequence of four sons of chain FC1-FC4 form at a end B (reweaving area B) of the band respectively no loop, a small loop, no loop and a large loop. The turns of a first spiral 30 are meshed with the loops formed at this end of the strip and are held by a first rod 31 passed in a defined channel by the small loops and the turns of the spiral. A second ring 32 has passed in a channel defined by the large loops and the turns of the spiral 30. This construction is identical on the other end of the strip (not shown). In particular, at the other end of the strip, small and large loops of this end of the strip are meshed with the turns of a second spiral 33 held by a third rod passed through a third channel formed by the small loops and the turns and by a fourth rod passed in a fourth channel formed by large loops and turns. The two spirals 30.33 thus mounted at each end of the strip are joined by a rod 34 now attached to the coiled turns of the two spirals. The length of the loops formed at each end of the strip and the diameter of the rods 31 and 32 are calculated in such a way that after joining the two ends of the strip and its running tension, the end of the small loops press on the rod 32 passed in the large loops making thus united in effort and tensile strength the small loops and large curls. The resistance of the junction is maximum and comparable to that of the embodiment described in FIG. 3. Furthermore, the large loops and the second ring 32 prevents the spiral 30 from pivoting around the first ring 31 and reduces the air permeability of the spiral area which contributes to reduce the risk of wear on the first rod 31 and marking of the sheet paper. Each spiral has a thickness identical to that of the strip and the width of the monofilament of each turn of the spirals must not be greater than 80% of the width of a chain wire.

FIG. 5 illustrates a third embodiment of loops joining formed only at one end B 'of a woven strip according to the invention for joining the two ends of the strip using a spiral 35. The spiral 35 is permanently fixed at the end of manufacture of the strip at the other end B thereof by bending the chain wires FC2 and FC4, during the reweaving, around the heel of the turns of the spiral and of a rod 36. At the end B ′ of the strip shown in FIG. 5, loops are formed separated two by two by a free space. We see in this figure that the sequence of four sons of chain FC1-FC4 form at this end B 'of the band respectively no loop, one loop, no loop, one loop. The turns of the spiral 35 are meshed with the loops and a rod 37 is passed through the channel defined by the loops and turns. Free space to the inside of the spiral can be filled with stuffing rods such as 38 so as to reduce the permeability of the junction zone.

Figure 6 shows a construction of the joining area similar to that of Figure 5 except that the loops are grouped in pairs and the pairs of loops are separated by pairs of free spaces. In particular, we see on this figure that the sequence of four chain wires consecutive FC1-FC4 respectively form no loop, no loop, a loop and a loop at the end B 'of the strip. This construction allows reduce the number of turns of the spiral 35 and increase the width of the monofilament constituting each turn.

In the embodiments as shown in FIGS. 5 and 6, the turns of the spiral must have a width LS following the direction of the wires weft less than 80% of the width LF of a warp thread (Figure 5) or two threads chain (Figure 6). The resistance of the junction is maximum and can be equal to that of the strip in zones B, B 'if the spiral has a resistance similar to that of the band. The advantage of using a spiral according to the embodiments of the figures 5 and 6 is to make it possible to mesh the two ends of the strip by having a junction width narrower than that of the embodiment of Figure 3 which helps reduce the risk of marking the sheet of paper.

It is understood that the invention which has just been described also applies to woven strips having two or more weft yarn planes. The woven band according to the invention can advantageously also be used in machines for manufacture of non-woven sails such as layers for infants, paper towels, geotextiles, etc.

Claims (9)

1. A woven strip (10) having asymmetrical weave constituted by weft yarns (11-15, 17-24) and warp yarns (16) extending between two opposite ends of the strip, the warp yarns being folded back at each end of the strip and re-woven with weft yarns over a re-weaving zone (B, B') adjacent to said end so as to form loops (27), the strip being characterized in that each re-weaving zone is of symmetrical weave.
2. The strip of claim 1, in which the warp yarns (16) are folded orthogonally to the plane of the strip at each end thereof, and in that the weft yarns (17-24) in the re-weaving zones are smaller in diameter than the weft yarns (11-15) in the remainder of the strip.
3. The strip of claim 2, comprising a single plane of weft yarns and in which the difference between the diameter of a weft yarn in the re-weaving zones and the diameter of a weft yarn in the remainder of the strip is equal to twice the thickness of a warp yarn.
4. The strip of either one of claims 2 and 3, in which the warp yarns at each end of the strip form small loops and large loops which project relative to the small loops, and in which the small loops at a first end of the strip co-operate with the large loops at the other end of the strip to define a first channel in which a first rod (28) is received, and the large loops at the first end of the strip co-operate with the small loops at the other end of the strip to define a second channel in which a second rod (29) is received.
5. The strip of either one of claims 2 and 3, in which the warp yarns at each end of the strip form small loops and large loops which project relative to the small loops, the small and large loops at one end of the strip being meshed with the turns of a first spiral (30) held by a first rod (31) received in a first channel formed by the small loops and by the turns, and by a second rod (32) received in a second channel formed by the large loops and the turns, the small and large loops at the other end of the strip being meshed with the turns of a second spiral (33) held by a third rod received in a third channel formed by the small loops and the turns, and by a fourth rod received in a fourth channel formed by the large loops and the turns, the turns of the first spiral (30) being meshed with the turns of the second spiral (33) and being held together by a fifth rod (34).
6. The strip of either one of claims 2 and 3, in which the warp yarns at one end of the strip form loops and are re-woven at the other end of the strip so as to hold the turns of a spiral (35), and in which the turns of the spiral are meshed with the loops so as to define a channel in which a rod (37) is received.
7. The strip of any preceding claim, in which the warp yarns (16) are of flat section.
8. The use of a strip of any one of claims 1 to 7, in a drier section of a papermaking machine.
9. The use of a strip of any one of claims 1 to 7, in a machine for making non-woven web material.

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