The invention relates to a multi-axial fabric, a method of weaving a multi-axial fabric and a loom for weaving a multi-axial fabric.

Woven fabrics are generally bi-axial fabrics including warp and weft yarns extending in two generally perpendicular directions.

In some applications, such as the creation of composite structures using woven fabrics, it is necessary to create a fabric having a three dimensional structure and this has conventionally been achieved through the use of separate layers of fabric.

However the creation of a three dimensional structure through the use of separate layers of fabric is time consuming in terms of the time required to cut and lay the separate layers of fabric. In addition, there is a risk of de-lamination of the separate layers. It is desirable therefore to provide a multi-axial woven fabric

According to a first aspect of the invention there is provided a multi-axial fabric comprising: a plurality of first biasing yarns extending in a first direction; a plurality of second biasing yarns extending in a second direction, the second direction being a first predetermined angle that preferably but not necessarily is perpendicular to the first direction; and a plurality of binder yarns extending in a third direction, the third direction being offset by a second predetermined angle, preferably but not necessarily 45°, to each of the first and second directions, wherein the first and second biasing yarns define first and second structural layers and the binder yarns are interwoven with the yarns of the structural layers to hold the structural layers together.

This fabric defines a multi-axial structure including structural yarns, which provide strength, and binder yarns, which hold the structural yarns together.

It also provides a structure in which the structural yarns are held in a straight configuration, which further strengthens the structure and renders it more resistant to stretch. Other advantageous features of the first aspect of the invention are recited in the attached claims that are dependent on Claim 1.

According to a second aspect of the invention there is provided a method of weaving a multi-axial fabric comprising the steps of: feeding a plurality of upper biasing yams through a plurality of equidistantly spaced upper picks; feeding a plurality of lower biasing yarns through a plurality of lower picks aligned with and spaced below the upper picks; feeding a plurality of binder yarns through a plurality of guide members located between laterally adjacent picks of the upper and lower picks downstream of the upper and lower picks; while feeding the upper and lower biasing yarns through the upper and lower picks respectively, and feeding the binder yarns through the guide members, moving each of the guide members between a first position where the respective binder yarn extends above the upper biasing yarns and a second position where the respective binder yarn extends below the lower biasing yarns; and between movement of the guide members between the first and second positions, moving each of the upper biasing yarns a single pick in a first direction along the upper picks and moving each of the lower biasing yarns a single pick in a second, opposite, direction along the lower picks.

Other advantageous features of the second aspect of the invention are recited in the attached claims that are dependent on Claim 11.

As used herein the term "pick" generally refers to a metal or other rigid member that is capable of engaging a yarn. Accordingly, references to movement of a yarn by a pick are to movement by a distance generally corresponding to the spacing between a pair of adjacent picks.

According to a third aspect of the invention there is provided a method of weaving a multi axial fabric comprising the steps of: feeding a plurality of upper biasing yarns through a plurality of equidistantly spaced upper picks; feeding a plurality of lower biasing yarns through a plurality of lower picks aligned with and spaced below the upper picks; feeding a plurality of binder yarns through a plurality of guide members located between laterally adjacent picks of the upper and lower picks downstream of the upper and lower picks; while feeding the upper and lower biasing yarns through the upper and lower picks respectively, and feeding the binder yarns through the guide members, moving the guide members between a first position where the binder yarns extend above the upper biasing yarns and a second position where the binder yarns extends below the lower biasing yarns; between movement of the guide members from one of the first and second positions to the other of the first and second positions, feeding a weft yarn between the adjacent biasing yarns and the binder yarns; and between movement of the guide members from the other of the first and second positions to the one of the first and second positions, moving each of the upper biasing yarns a single pick in a first direction along the upper picks and moving each of the lower biasing yarns a single pick in a second, opposite, direction along the lower picks.

Other advantageous features of the third aspect of the invention are recited in the attached claims that are dependent on Claim 20.

According to a fourth aspect of the invention there is provided a loom for weaving a multi axial fabric comprising: a feed apparatus defining a plurality of equidistantly spaced upper picks to receive a plurality of upper biasing yarns and a plurality of lower picks to receive a plurality of lower biasing yarns aligned with and spaced below the upper picks; an upper drive member associated with the upper picks to move selectively yarn received in each of the upper picks a single pick in a first direction along the upper picks; a lower drive member associated with the lower picks to move selectively yarn received in each of the lower picks a single pick in a second, opposite, direction along the lower picks; a plurality of guide members located between laterally adjacent picks of the upper and lower picks downstream of the upper and lower picks to receive a plurality of binder yarns, each guide member being movable, in use, between a first position where the respective binder yarn extends above the upper biasing yarns and a second position where the respective binder yarn extends below the lower biasing yarn; and a feeder to feed upper and lower biasing yarns and binder yarns through the loom. Other advantageous features of the fourth aspect of the invention are recited in the attached ciaims that are dependent on Claim 26.

Preferred embodiments of the invention will now be described, by way of non-limiting examples, with reference to the drawings in which:

Figure 1 is a schematic illustration of a fabric according to an embodiment of the invention;

Figures 2 and 3 are schematic illustrations of a fabric according to a further embodiment of the invention;

Figure 4 shows a loom for making a fabric in accordance with the invention;

Figures 5 to 7 and Figures 8a to 8d illustrate operation of the loom of Figure 4 in one configuration; and

Figure 9 illustrates operation of the loom of Figure 4 in another configuration.

Multi-axial fabrics 10 according to embodiments of the invention are shown in Figures 1 to 3.

Each of the fabrics 10 includes a plurality of first biasing yams 12 extending in a first direction signified by arrow A and a plurality of second biasing yarns 14 extending in a second direction signified by arrow B, which is (in the embodiment shown) generally perpendicular to the first direction A. Each of the fabrics 10 includes a plurality of binder yarns 16 extending in a third direction signified by arrow C, which is offset by (in the embodiment shown) 45° to each of the first and second directions A ₁ B. Other angles subtended between the yarns are possible within the scope of the invention, and may be achieved e.g. by choosing appropriately the rate of feed of the yarns through a loom, described below, as part of a method also described below.

The first and second biasing yarns 12,14 define first and second structural layers 13,15 (Figure 3) and a plurality of warp yarns 18 extending in the third direction C, generally parallel to the binder yarns 16, define a further, warpwise, structural layer lying 17 between the first and second structural layers 13,15.

Each of the fabrics 10 also includes a plurality of weft yarns 20 extending in a fourth direction signified by arrow D, which is generally perpendicular to the third direction C, defining a weftwise structural layer 19. The binder yarns 16 are interwoven with the yarns 12,14,18,20 of the structural layers 13,15,17,19 so as to hold the structural layers together, as illustrated schematically in Figure 3.

In each of the fabrics 10, the weftwise structural layer 19 defined by the weft yarns 20 is located between the first structural layer 13 and the binder yarns 16, and forms an outer layer of the fabric 10.

Referring to the fabric 10 shown in Figure 1, it can be seen that the manner of insertion of the warp and weft yarns 18,20 in this fabric results in a structure in which the first and second biasing yarns 12,14, the warp yarns 18 and the weft yarns 20 all lie against each other at cross-over points in the fabric structure. This arrangement results in a structure in which each of the structural layers is necessarily spaced from the or each neighbouring structural layer.

In contrast, referring to the fabric 10 shown in Figure 2, it can be seen that the manner of insertion of the warp and weft yarns 18,20 in this fabric results in a structure in which a maximum of three of the different yarns 12,14,18,20 lies against each other at any crossover point within the structure. This in turn results in a structure in which the structural layers lie closer to each other than the structural layers of the fabric 10 shown in Figure 1.

The closer the structural layers of the fabric 10 lie relative to each other, the less space is available for resin in a composite structure constructed using the fabric 10. This in turn increases the strength of the resultant composite structure.

In each of the embodiments shown in Figures 1 to 3, a single weftwise structural layer 19 is provided. It is however envisaged that in other embodiments, a plurality of weftwise yarns may be provided on the opposite side of the fabric, thereby resulting in weftwise structural layers forming outer layers on opposite sides of the fabric.

It is also envisaged that in other embodiments the warpwise structural layer 17 may be located between one of the first and second structural layer 13,15 and an outer weftwise structural layer instead of between the first and second structural layers.

In yet further embodiments, a fabric according to an embodiment of the invention may omit the warp 18 and/or weft yarns 20, thereby resulting in a fabric having three or two axes, as required. For example, the warp yarns 18 may be omitted from the fabric 10 shown in Figure 1 and the warp 18 and/or the weft yarns 20 may be omitted from the fabric 10 shown in Figure 2, the interwoven relationship between the binding yarns 16 and the yarns of the remaining structural layers serving to hold the remaining structural layers together.

The binder yarns 16 may be formed from the same material as the yarns forming the structural layers or may be formed from a different material, depending on the application in which the fabric 10 is to be used.

A loom 22 for making a fabric according to the invention is shown in Figure 4 and includes a feed apparatus 24 including a pair of horizontally extending front plates 26a, 26b, the front plates 26a, 26b being aligned and spaced vertically from each other.

The uppermost front plate 26a includes a plurality of equidistantly spaced grooves, which define upper picks 28 to receive a plurality of upper biasing yarns 30, as illustrated in Figure 8a.

The lowermost front plate 26b includes a plurality of grooves, aligned with and opposed to the grooves of the uppermost front plate 26a, which define lower picks 32 to receive a plurality of lower biasing yarns 34.

The loom 22 also includes a pair of horizontally extending back plates 36a, 36b, which are aligned and spaced vertically from each other, and define correspondingly shaped, sized and oriented grooves 37a, 37b to the grooves defining the upper and lower picks 28,32 in the front plates 26a, 26b.

Each of the back plates 36a, 36b is mounted adjacent a respective one of the front plates 26a,26b so as to be movable vertically and horizontally relative to the front plate 26a,26b.

The feed apparatus 24 also defines a plurality of channels 44 to receive a plurality of warp yarns 46 from a creel or beam 45 located upstream of the feed apparatus 24.

In the configuration of operation illustrated in Figures 5 to 7, the channels 44 are arranged to feed warp yarns 46 between the upper and lower biasing yarns 30,34. In other configurations of operation the channels 44 may be arranged to feed warp yarns 46 above the upper and lower biasing yarns 30,34, as shown in Figure 9, or to feed warp yarns 46 below the upper and lower biasing yarns 30,34.

In the embodiment shown in Figure 9, upper and lower biasing yarns 30,34 are fed to the upper and lower picks 28,32 respectively from a plurality of individual yarn sources 40 mounted on a feed assembly 42. The feed assembly 42 is provided in the form of a wheel mounted between the creel 45 and the feed apparatus 24 so as to be rotatable about the warp yarns 46 extending into the channels 44 from the creel 45, and the individual yarns sources 40 are mounted in sequence about its outer circumference.

Bars 41 ,43 located above and below the warp yarns 46 act to push the upper biasing yarns 30 into the upper picks 28 and the lower biasing yarns 34 into the lower picks 32.

A plurality of guide members 48 are located between laterally adjacent picks of the upper and lower picks 28,32 and downstream of the upper and lower picks 28,32, to receive a plurality of binder yarns 50.

In the configuration of operation illustrated in Figures 5 to 7, each of the guide members 48 is provided in the form of a heald rod including an eye 52 through which a respective binder yarn 50 is threaded.

Preferably each binder yarn 50 is guided via a respective one of the channels 44 through which the warp yarns 46 are fed before being threaded through the eye 52 of a respective guide member 48.

Each of the guide members 48 is movable in a cyclic motion from a first position shown in Figure 5, via an intermediate position shown in Figure 6, to a second position shown in Figure 7 and back to the first position.

In the first position, each of the guide members 48 is located adjacent the uppermost front plates 26a such that the respective binder yarn 50 extends above the upper biasing yarns 30.

In the intermediate position, each of the guide members 48 moves down and away from the uppermost front plate 26a such that the binder yarn 50 extends generally parallel to the adjacent warp yam 46. In the second position, each of the guide members 48 is located adjacent the lowermost front plate 26b such that the respective binder yarn 50 extends below the lower biasing yams 34.

The loom 22 also includes a weft insertion system 54, preferably in the form of one or more rapiers, to selectively insert a weft yarn 56.

During operation of the loom 22 in one configuration, adjacent guide members 48 are arranged to move in the same direction as each other so that all guide members 48 move at the same time cyclically from the first position, via the intermediate position, to the second position.

While the guide members 48 are located in the first position, a shed 58 is defined between the binder yarns 50 and the upper biasing yarns 30 through which a rapier 54 is inserted in order to insert a weft yarn 56, as shown in Figure 5.

Following insertion of the weft yarn 56, the guide members 48 move forward and down to the intermediate position in which position they act as reeds and beat up the weft yarn 56 into the fabric, as shown in Figure 6.

The guide members 48 then move backward and down to the second position, as shown in Figure 7.

When the guide members 48 are located in the second position, the uppermost back plate 36a moves downward to locate the upper biasing yarns 30 in grooves 37a defined therein and move the upper biasing yarns 30 out of the grooves defined in the uppermost front plate 26a, as illustrated in Figure 8b. Similarly the lowermost back plate 36b moves upward to locate the lower biasing yams 34 in the grooves 37b defined therein and move the lower biasing yarns 36 out of the grooves defined in the lowermost front plate 26b.

The uppermost back plate 36a then moves one pick in a first direction so as to move each of the upper biasing yarns 30 one pick in a first direction along the upper picks 28, as illustrated in Figure 8c. Similarly the lowermost back plate 36b moves one pick in a second, opposite, direction along the length of the lower picks so as to move the lower biasing yams 34 one pick in a second, opposite, direction along the lower picks 32. The uppermost back plate 36a then moves upward and bar 41 acts to locate each of the upper biasing yarns 30 back into the upper picks 28 one pick along in the first direction, as illustrated in Figure 8d. Similarly the lowermost back plate 36b moves downward and bar 43 acts to locate each of the lower biasing yarns 34 back into the lower picks 32 one pick along in the second direction.

In this manner, the back plates 36a, 36b act as upper and lower drive members to move selectively yarn received in the upper and lower picks 28,32 one pick, in opposite directions, along the upper and lower picks 28,32.

During movement of the back plates 36a,36b, the feed assembly 42 rotates so as to reposition the individual yarn sources 40 relative to the appropriate one of the upper or lower picks 28,32.

Continued operation of the loom 22 in this manner results in the upper biasing yarns 30 being drawn into the resultant fabric in a first direction at 45° to the warp yarns 46 and the lower biasing yarns 34 being drawn into the resultant fabric in a second direction, which is generally perpendicular to the first direction.

When each of the upper biasing yams 30 reaches the last of the upper picks 28 in the first direction it is directed to the first of the lower picks 32 during operation of the back plates 36a, 36b.

Similarly, when each of the lower biasing yarns 34 reaches the last of the lower picks 32 in the second, opposite, direction it is directed to the first of the upper picks 28 during operation of the back plates 36a,36b.

Continued rotation of the feed assembly 42 during continued operation of the loom results in each of the individual yarn sources 40 moving in a cyclic motion between positions in which yarn from the yarn source is fed sequentially in the first direction through each of the upper picks 28 and positions in which yarn from the yarn source is fed sequentially in the second direction through each of the lower picks 32.

Operation of the loom in this configuration of operation results in the fabric structure shown in Figure 1. This fabric structure may be altered by inserting a weft yarn 56 through the shed created while the guide members 48 are located in the second position in addition to when the guide members 48 are located in the first position so as to locate weft yarns 56 under the lower biasing yarns 34 as well as over the upper biasing yarns 30.

This fabric structure may be further altered by inserting a weft yarn 56 through the shed created while the guide members 48 are located in the second position instead of when the guide members are located in the first position so as to locate weft yarn 56 under the lower biasing yarns 34 instead of over the upper biasing yarns 30.

This fabric structure may be yet further altered by omitting the warp yarns 46 so as to produce a fabric having three axes instead of a fabric having four axes.

Yet further alterations may be effected by adjusting the feed speeds of the yarns through the loom.

In another configuration of operation, adjacent guide members 48 may be arranged to move in opposite directions to each other so that alternate guide members move from the first position via the intermediate position to the second position while the intervening guide members move from the second position via the intermediate position to the first position, the cyclic motion of each guide member 48 including movement from the first position via the intermediate position to the second position and from the second position via the intermediate position to the first position.

In such a configuration of operation, the back plates 36a,36b may be operated to move the upper and lower biasing yarns 30,34 one pick in opposite directions respectively along the upper and lower picks 28,32 while one group of the guide members 48 is located in the first position as well as when the other group of guide members 48 is located in the first position.

If a weft yarn 56 is also inserted each time one of the groups of guide members 48 is located in the first position, this configuration results in the fabric structure shown in Figure 2.

This fabric structure may be altered by inserting a weft yarn 56 through the shed created each time one of the groups of guide members 48 is located in the second position in addition to when one of the groups of guide members 48 is located in the first position so as to locate weft yarns 56 under the lower biasing yarns 34 as well as over the upper biasing yarns 30.

This fabric structure may be further altered by inserting a weft yarn 56 through the shed created when one of the groups of guide members 48 is located in the second position instead of when one of the groups of guide members is located in the first position so as to locate weft yarn 56 under the lower biasing yarns 34 instead of over the upper biasing yarns 30. ,

This fabric structure may be yet further altered by omitting the weft yarns 56 and/or the warp yarns 46 so as to produce fabrics having two or three axes instead of a fabric having four axes.