Patent Description:
Woven structures are known. Woven structures are made of multiple picks along the formation direction. In some traditional weaving techniques, the term "pick" describes one fill fiber that has been deposited and encapsulated by the entire array of warp fibers one row at a time. The term "pick" may apply to encapsulation of the fill fiber by one adjacent pair of warp fibers at a time.

Many components, such as ceramic matrix composite (CMC) or organic matrix composite (OMC) components used in a jet engine, use woven structures as preforms. The woven structure strengthens the component. During manufacturing of such components, the woven structure is placed in a mold as a precursor. A material is then injected into the remaining areas of the mold. The injected material or resin surrounds the woven structure within the mold. If the mold has varying contours, manipulating woven assemblies, which are relatively planar, into a shape suitable for placing into the mold is difficult. Methods for forming three dimensional woven structures are desired.

<CIT> discloses a method of forming a woven structure which includes placing a first section of a fill fiber between warp fibers, forming a pick, moving a base to reposition the warp fibers, and placing a second section of the fill fiber between the warp fibers and repeating to form a woven structure. The base provides a grid for retaining an array of warp fibers. <CIT> discloses a method of three-dimensionally weaving fibers wherein rods, which grasp warp fibers at one end, are arranged side by side in a Z direction on a base. A weaving head sends weft yarns between the rods in the XY plane. Again, the base provides a grid for retaining an array of warp fibers.

According to one aspect of the present invention, there is provided a weaving method as claimed in claim <NUM>.

The weave control grid may be affixed to the base.

The weave control grid may have a central opening.

According to another aspect of the present invention, there is provided a weaving method as claimed in claim <NUM>.

The method may include repositioning warp fibers by moving a base relative to the fill fiber wand.

Warp fibers may be positioned by the weave control grid prior to forming the first pick or second pick.

The weave control grid may be attached to the base.

According to another aspect of the present invention, there is provided a weaving assembly as claimed in claim <NUM>.

The weaving assembly may include a holding station. The holding station may be a secondary weave control grid.

The weave control grid may have an open central section.

The weave control grid location may be controlled by a positional controller.

The weave control grid may have openings with variable spacing between openings.

The weaving assembly may include additional weave control grids.

The following descriptions should not be considered limiting but are provided by way of example only.

A detailed description of one or more embodiments of the disclosed assembly and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring to <FIG>, an example weaving assembly <NUM> is used to weave a woven structure <NUM>. The weaving assembly <NUM> includes a wand <NUM>, a base <NUM>, weave control grid <NUM>, and a plurality of warp fiber arms <NUM>. The weave control grid is shown in <FIG> and <FIG>.

When weaving the woven structure <NUM>, the wand <NUM> positions a fill fiber <NUM> between warp fibers <NUM>. Controlled spacing of the warp fibers is important to provide consistent production of the woven structure. The fill fiber <NUM> extends from a spool <NUM> through a bore <NUM> in the wand <NUM>. The wand <NUM>, in this example, is a hollow tube. A fill fiber feed device may be included to meter the feed rate of the fill fiber with respect to the instantaneous relative velocity of the wand tip to the textile being created. The warp fibers <NUM> are manipulated by warp fiber arms <NUM>.

The assembly <NUM> includes a positional controller <NUM> associated with the wand <NUM>, a positional controller <NUM> associated with the warp fiber arms <NUM>, and a positional controller <NUM> associated with the base <NUM>. The positional controller <NUM> is able to move the wand <NUM> relative to the warp fiber arms <NUM> and the base <NUM>. The positional controller <NUM> is able to move the warp fiber arms <NUM> relative to the wand <NUM> and the base <NUM>. The positional controller <NUM> is able to move the base <NUM> relative to the wand <NUM> and the warp fiber arms <NUM>. The positional controllers <NUM>, <NUM>, and <NUM> can be operated independently from each other or together.

The warp fiber arms <NUM> may be on the positional controller <NUM>, attached to the fill fiber wand controller <NUM>, or attached to the base positional controller <NUM>.

In this example, at least the positional controller <NUM> is a six-axis controller, and may be a six-axis robotic controller. That is, the positional controller <NUM> is able to move the base <NUM> relative to the warp fiber arms <NUM> in three dimensions and rotate around three axes. The positional controllers <NUM> and <NUM> may have similar characteristics.

Referring to <FIG>, the assembly <NUM> further includes a weave control grid <NUM> to position the warp fibers in close proximity to the desired position for weaving and with controlled spacing. Locating the warp fibers in close proximity to the desired position for incorporation into weaving and with controlled spacing results in a more consistent and precise woven structure with better reproducibility of physical characteristics between woven structures. The term "grid" as used herein describes a distribution pattern of openings with designated spacing. The desired spacing between grid openings may vary as needed to locate warp fibers in close proximity to the desired location for incorporation into weaving. For example, if adding a number of warp fibers in a small area the grid spacing may be smaller whereas in areas where fibers are being added over a larger area the spacing may be larger. The grid openings may be any shape or size that will permit the fibers to pass through.

The weave control grid <NUM> is slidably located below the addition point of the fill fiber from the wand <NUM>. <FIG> is a top view that shows the weave control grid <NUM> with fiber openings <NUM> and warp fibers <NUM> located in some of the openings. Fiber openings <NUM> are shown as square but may be any shape that will accommodate the warp fiber. The fiber openings <NUM> may also vary in size to more precisely locate specific fibers. The spacing between the openings is dependent upon the weave design.

<FIG> is a top view that shows the fill fiber <NUM> woven through a portion of the warp fibers <NUM>. <FIG> is a top view showing the fill fiber <NUM> woven through the warp fibers as in <FIG> and additional warp fibers.

When the weave control grid is slidably located below the addition point of the fill fiber wand the weave control grid has an open central section to accommodate the evolving woven structure. It is further contemplated that the weave control grid may be modular to permit changes to the size and shape of the central opening to accommodate changes in the size and shape of the evolving woven structure. When the weave control grid is slidably located the weave control grid may be associated with a positional controller which is able to move the weave control grid relative to the fill fiber wand.

Referring to <FIG> with continuing reference to <FIG> and <FIG>, the woven structure <NUM> includes multiple picks <NUM>. In this example, warp fibers <NUM> are crossed over multiple sections of the fill fiber <NUM> to form picks <NUM>. The warp fiber arms <NUM> are actuated to cross the warp fibers <NUM> over the fill fiber <NUM>, which entraps the fill fiber to form the pick <NUM>.

The example fill fibers <NUM> and warp fibers <NUM> may be composed of materials including glass, graphite, polyethylene, aramid, ceramic, boron and combinations thereof. One of the fill fibers <NUM> or warp fibers <NUM> may include hundreds or thousands of individual filaments. The individual filaments may have diameters that range from <NUM> to <NUM> microns, although boron filaments may be up to <NUM> microns in diameter.

In this example, each of the warp fiber arms <NUM> holds one of the warp fibers <NUM>. In other examples, the warp fiber arms <NUM> may hold several of the warp fibers <NUM>. After crossing the warp fibers <NUM> over the fill fiber <NUM>, the warp fiber arms <NUM> hand-off the warp fiber <NUM> to another of the warp fiber arms <NUM>. The "hand-off" feature allows an open shed so that the warp fiber arms <NUM> do not interfere with the wand <NUM>. After the hand-off, the warp fiber arms <NUM> are then crossed over another section of the fill fiber <NUM> to form another pick <NUM>.

The warp fiber arms <NUM> engage portions of the warp fibers <NUM>. These portions may include end fittings. The warp fiber arms <NUM> grab the end fittings holding the warp fibers <NUM>. The end fittings may be placed on a holding station to help maintain the position of the warp fibers <NUM> during weaving. In some embodiments the holding station has the form of a secondary weave control grid.

A person having skill in this art and the benefit of this disclosure would understand how to create picks by crossing warp fibers over a fill fiber, and how to hand-off a warp fiber from one warp fiber arm to another warp fiber arm.

When weaving, the wand <NUM> moves the fill fiber <NUM> past the warp fibers <NUM>. The wand <NUM> moves the fill fiber <NUM> back and forth to create built-up layers of picks <NUM>. The wand <NUM> is long enough to reach down through the longest warp fibers <NUM> during the weaving (<FIG>).

The base <NUM> is moved as dictated by the design of the woven structure <NUM> to create a bend <NUM> in the woven structure <NUM>. The base <NUM> is thus capable of movement relative to the warp fiber arms <NUM>.

The base <NUM> moves so that the pick formation point is at a position relative to the wand <NUM>, and the fill fiber <NUM>, appropriate for forming the bend <NUM>. Although only one substantial bend <NUM> is shown, the base <NUM> may manipulate the pick formation points to form a woven structure having various contours.

The base <NUM> may move the warp fibers <NUM> over a piece of tooling shaped to the final desired contour [e.g., a mandrel] that is attached to the base <NUM> to facilitate forming the bend <NUM>. The mandrel may move separately from the base <NUM>. In another example, the base <NUM> moves the warp fibers <NUM> without a mandrel to free-form the bend <NUM>.

The warp fibers <NUM> may be rigid enough to cantilever out from the base <NUM> (or shed) during the weaving. A binding agent such as polyvinyl alcohol is used, in some examples, to provide a degree of rigidity to the warp fibers <NUM>. The warp fibers <NUM> may have a fixed length. The fill fiber <NUM>, by contrast, can have length in excess of that needed to produce one component.

Alternatively, the warp fibers <NUM> may be soft and not rigid enough to cantilever out from the base. In other examples, metallic or plastic fittings may be added to the free ends of flexible warp fibers <NUM>. The fittings may be placed in holding stations, and the warp arms move the fittings from notch to notch as appropriate as the component is build up.

The fittings may take the form of a bead with a through-hole. Prior to weaving, the ends of the warp fibers <NUM> are inserted through the holes and bonded with an adhesive. The holding station may be a fixture that has notches to hold the non-rigid warp fibers by draping the fitting over the notch and having gravity provide tension. The fittings may also take the form of mechanisms that provide tension by the action of a spring, similar to carriers that hold spools of fiber on a braiding machine. The holding station may be attached to the base or may be independent of the motion of the base. The holding station may have a grid type spacing and function as a secondary weave control grid.

The path and manipulations of the base <NUM> with the positional controller <NUM>, the number of warp fibers <NUM> engaged by the warp fiber arms <NUM> when forming each pick, and the sequence of warp fiber arm movements may be designed and pre-planned in a software model to produce the woven structure <NUM> having the desired contours. A stable shape is obtained by the interplay of fiber forces and friction within the textile unit cells throughout the component.

The software model may utilize as inputs: a CAD definition of the surfaces of a desired component incorporating the woven structure; a definition of the initial warp fibers' lengths, locations, and orientations; and a definition of a textile repeating unit cell (or pick). The software calculates motions of the wand <NUM>, base <NUM>, warp fiber arms <NUM> and optionally the weave control grid necessary to achieve desired contours in the woven structure <NUM>, without colliding into each other. The software model is then used as input for the positional controllers <NUM>, <NUM>, <NUM>, and optional weave control grid positional controller and control of the fill fiber wand.

Separation S1 and separation S2 between warp fibers can be adjusted to adjust the shape of the woven structure <NUM>. The separations S1 and S2 may remain relatively consistent when forming the area shown in <FIG>. The separations S1 and S2 may be gradually increased after each pass of the fill fiber <NUM> to create a flanged area of the woven structure <NUM> shown in <FIG>.

Referring to <FIG>, in some examples a woven structure 14a may include multiple layers of the warp fibers <NUM>. The fill fiber <NUM> joins all three layers in this example. When weaving the woven structure <NUM> the warp fiber arms may selectively engage one, two, or more warp fibers.

Features of the disclosed method and assembly include a relatively precise and repeatable mechanized process that is conducive to high volume production of complex shape engine components with precise and repeatable introduction of warp fibers as the woven structure evolves.

Claim 1:
A weaving method comprising positioning a first section of a fill fiber (<NUM>) between warp fibers (<NUM>) using a fill fiber wand (<NUM>), forming a pick (<NUM>), moving a base (<NUM>) to reposition the warp fibers wherein at least a portion of the warp fibers are secured to the base, and positioning a second section of the fill fiber between the warp fibers using the fill fiber wand to form a woven structure (<NUM>), wherein at least a portion of the warp fibers are introduced to the woven structure using a weave control grid (<NUM>) comprising a distribution pattern of openings (<NUM>) through which the warp fibers are located such that the warp fibers are positioned in close proximity to the desired position for weaving and with controlled spacing,
characterized in that:
the weave control grid (<NUM>) is slidably located below the fill fiber wand (<NUM>) and the method comprises repositioning the weave control grid (<NUM>) relative to the fill fiber wand (<NUM>).