GB2332215A - Loom reeds - Google Patents

Abstract

A reed for a loom comprises at least two rows of teeth (24, 25), arranged so that one row is located behind the other row in the direction of yarn feed, the teeth of row 25 being offset with respect to the teeth of row 24, so that the rows of teeth combine to define dents of lesser width than the gaps between the teeth of each row. Three rows of teeth may be provided in a further embodiment.

Description

2332215 Loom Reeds This invention relates to loom reeds particularly for

weaving industrial textiles especially phase separation media such as papermachine clothing such as forming belts, filter media particularly filter belts, and conveyer belting.

When weaving e.g. filter cloths intended for precise separation of particles above and below a threshold particle size, it is extremely important that a woven filter cloth be manufactured with an even structure, so that the boundary between retained and passed particles is as well defined as possible, and does not vary at different parts of the cloth.

In a loom, the reeds are comb-like members having a multiplicity of teeth, through the gaps in which (dents), warp yarns are fed to create the warp. The teeth of the reeds are in the form of wires, rods or thin metal strips, and are of a length sufficient to allow the shedding of warp threads to take place between each weft thread pick or group of weft thread picks, and beat-up the woven weft threads by moving the reed up to the shed. The reeds are mounted in sley-frames which are operated to carry out the beating-up motions.

It is often necessary when weaving dense fabrics of fine yarns to draw in more than two warp yarns through each dent of the reed. This is done because it is difficult to manufacture reeds with thin enough teeth and -2at the same achieve a stable reed which can withstand the forces arising in beating up the weft threads. When three or more weft threads are drawn in per dent, uneven warp tension arises between the warp yarns which are in contact with the flanks of the teeth, and the remaining warp yarns which have no contact with the reed teeth. Such differences in warp tension give rise to repeated unevenness in the weave structure (repeating with each dent group of warp yarns) which result in a woven product, such as a filter cloth, of inferior quality. In the case of filter cloths in particular, the variation in yarn tension results in variation in the dimensions of filtration pores, so that there is an unacceptable spread in the lower dimensions of retained particles, making the filter cloth useless for sensitive filtration, where precise particle size discrimination is required.

An object of the invention is to provide a construction of loom reed which promotes even warp tension in weaving of dense fabrics, thereby assuring that variation in pore size are minimised.

According to the invention a reed for a loom comprises at least two rows of teeth, one row of said teeth being located behind the other row, in the direction of the warp yarns drawn into the reed, the teeth of the said one row being offset with respect to the teeth in the said one row, so that the rows of teeth combine to define dents of lesser width than the gaps between the teeth of each row. The invention also provides a sley in a -3loom provided with reeds according to the invention.

The reed may comprise two such rows of teeth which are offset with respect to each other by half the spacing of the teeth in each such row.

Alternatively the reed may comprise three such rows of teeth, each succeeding row being offset with respect to the adjacent row or rows by one third of the spacing of the teeth in each row.

Higher numbers of rows may be used, with appropriate offset spacings of the teeth, to be the limit of practicability for creating dents for drawing in at least one warp yarn to each of the resulting dents.

The teeth of each row may be rigid wires or rods, but are preferably thin strips of e.g. metal.

The invention will now be further described by way of example with reference to the accompanying drawings, wherein:- Fig. 1 is a diagrammatic view of the warp shed of a loom, showing the location of a reed in the loom; Figs. 2a-e illustrate the prior art, with a reed comprising a single row of teeth, showing in:-

Fig. 2a - a single yarn drawn through each dent; Fig. 2b - two yarns drawn through each dent; Fig. 2c - three yarns drawn through each dent; Fig. 2d - four yarns drawn through each dent; Fig. 2e - five yarns drawn through each dent; Fig. 3 is a diagrammatic side view of a first embodiment of loom reed according to the invention; Fig. 4 is a view similar to Fig. 3 of an alternative reed with two rows of teeth; Fig. 5 is a view similar to Fig. 3 of a reed comprising three rows of teeth; Fig. 6 is a diagram similar to Figs. 2a - e, showing a reed with two rows of teeth with three yarns drawn through each dent of the front row; and Fig. 7 is a view similar to Fig. 6 wherein five yarns are drawn through each dent of the front row.

Fig. 1 is a diagrammatic generalised view of the warp shed of a loom. Warp yarns 10 are drawn through a reed 11, to a fabric 12. The warp yarns are shed as at 13a, 13b to allow for picking of weft yarns into the shed, in known manner. The reed 11 maintains spacing of the warp yarns 10, and is used to beat the weft yarns up into the shed.

Figs. 2a to 2e illustrate the use of a reed 11 of known type, comprising an array of teeth 14, each separated by a space or dent 15, with increasing numbers of warp yarns drawn into each dent. Thus in Fig. 2a, a single warp yarn 10 is drawn into each dent 15. In Fig. 2b, two yarns 10 -5are drawn into each dent, and in Figs. 2c, 2d and 2e, three, four and five warp yarns 10 are drawn into each dent 15.

In Fig. 2a, even yarn spacing is assured by having one yarn to each dent, in Fig. 2b each yarn 10 can contact one face of the teeth 14, and even spacing is again assured. However, in Figs. 2c-2e increasing numbers of the warp yarns 10 do not cooperate with a guiding tooth surface, and thus there is nothing to counteract a tendency of the yarns to bunch to one side or other of the dent, leaving a void towards the other.

Figs. 3 and 4 illustrate embodiments of reed according to the invention with two rows of teeth. The reed 21 comprises two frames 22, 23 one set behind the other, in the direction of the warp threads. Frame 22 has a first set of teeth 24, and frame 23 a second set of teeth 25. Teeth 25 are located behind teeth 24, and are located so as to be spaced half way between successive teeth 24 as viewed along the warp thread direction. In Fig. 4 the two sets of teeth 24, 25 are held in a single frame 22, with the received set 25 bent away from the first set 24 to provide a space between them.

Fig. 5 illustrates a second embodiment of reed 30 according to the invention, comprising a frame 31 in which are mounted three sets of teeth, 32, 33 and 34. Fig. 5a is a fragmentary plan section of the reed of Fig. 5, and shows that sets of teeth 33, 34 are spaced with respect to teeth 32, -6at intervals of one third of the distance between adjacent teeth 32, to subdivide the dent between teeth 32 into three equal sub-dents.

Fig. 6 and 7 illustrate the use of a multi row reed, similar to that of Figs. 3 and 4, to draw in three and four yarns respectively to each dent of the front row teeth 24. In Fig. 6, with three yarns 10 drawn in, one yarn passes above each tooth 24, to abut the lower side of the next tooth 25 of the second row, whilst two yarns 10 pass below each tooth 24 and above the next tooth 25. Each yarn 10 contacts at least one tooth 24 or 25 in one or other of the rows. Similarly in Fig. 7, with four yarns 10 drawn in to each front row dent, a pair of yarns passes above each tooth 24 and below the next tooth 25, and another pair below each tooth 24 and above the next tooth 25. Each yarn again contacts one or other of the front teeth 24 or the rear teeth 25. In the three row embodiment of Fig. 5, up to six yarns per front row dent may be drawn in whilst assuring that each yarn contacts at least one tooth.

The reeds are mounted in a sley-frame which is operated to carry out the beating-up movements.

By this means it is thus possible to maintain even spacing of the warp yarns up to high numbers of drawn in yarns, with very dense and fine fabrics. Even spacing of the warp yarns in turn ensures that the designed filtration characteristics of a filter fabric, or other phase separation medium can be maintained within acceptable limits.

Claims (9)

1. -8CLAIMS

   A reed for a loom, the reed comprising at least two rows of teeth, one row of said teeth being located behind the other row in the direction of warp yarns drawn into the reed, the teeth of said one row being offset with respect to the teeth in said other row, so that said rows of teeth combine to define dents of lesser width than the gaps between the teeth of each row.
2. 2. A reed according to claim 1 which comprises two such rows of teeth which are offset with respect to each other by half the spacing of the teeth in each such row.
3. 3. A reed according to claim 1 which comprises three such rows of teeth, each succeeding row being offset with respect to the adjacent row or rows by one third of the spacing of the teeth in each row.
4. 4. A reed according to claim 1 wherein there are four or more such rows of teeth, each succeeding row being offset with respect to the adjacent row or rows by the respective reciprocal fraction of the spacing of the teeth in each row.
5. 5. A reed according to any preceding claim wherein the teeth of each row are rigid wires or rods.
6. 6. A reed according to any one of claims 1 to 4 wherein the teeth of each row are thin strips of metal.
7. 7. A reed for a loom, substantially as hereinbefore described with -9reference to and as illustrated in any of Fig 3 to Fig 7 of the accompanying drawings.
8. 8. A sley in a loom having one or more reeds, as set out in claims 1 to 7.
9. 9. A loom equipped with a sley according to claim 8, or one or more reeds according to any of claims 1 to 7.