Patent Description:
Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.

The rotor blades generally include a suction side shell and a pressure side shell typically formed using molding processes that are bonded together at bond lines along the leading and trailing edges of the blade. Further, the pressure and suction shells are relatively lightweight and have structural properties (e.g., stiffness, buckling resistance and strength) which are not configured to withstand the bending moments and other loads exerted on the rotor blade during operation. Thus, to increase the stiffness, buckling resistance and strength of the rotor blade, the body shell is typically reinforced using one or more structural components (e.g. opposing spar caps with a shear web configured therebetween) that engage the inner pressure and suction side surfaces of the shell halves.

In addition, conventional rotor blades require a substantial amount of bond paste to provide structure at various blade joints (e.g. at the leading or trailing edges of the rotor blade) to prevent local buckling of the suction and pressure side shells. Due to the complex geometry near these joint areas, it is often difficult to provide this structure in other ways that would be lighter than bond paste. Thus, conventional rotor blades typically utilize excess paste for the structure needed at the joints. Such excess paste, however, is expensive, heavy, and can limit the types of adhesives that can be used. For example, heavy and thick adhesive sections containing fast curing adhesives with high exothermic reactions can generate excess heat and damage the surrounding materials, thereby creating safety hazards.

In view of the foregoing, the art is continually seeking improved methods for joining blade components of rotor blades that use less adhesives.

<CIT> discloses a method of manufacturing a rotor blade for a wind turbine. The method includes providing a blade mold of the rotor blade, placing an outer skin layer in the blade mold, placing one or more structural inserts in the blade mold atop the outer skin layer as a function of a load of the rotor blade and placing an inner skin layer atop the one or more structural inserts and securing the outer skin layer, the one or more structural inserts, and the inner skin layer together to form the rotor blade.

<CIT> discloses method and system for assembling large wind turbine blades that includes providing a plurality of wind turbine blade segments. An adhesive distribution arrangement is disposed on a surface of at least one of the plurality of the wind turbine blade segments. The adhesive distribution arrangement includes a bonding grid having a plurality of adhesive distribution openings. The wind turbine blade segments are directed together and sufficient adhesive is provided to the bonding grid to substantially fill an area between the wind turbine segments. The adhesive is then cured to form a bonded joint, the bonding grid being incorporated into the bonded joint. A bonding grid for use with the method and system and a segmented wind turbine blade are also disclosed.

<CIT> discloses a hollow wind turbine blades and the like comprising abutting blade sections, with nose forming strips and converging walls forming a tail section connecting with the ends of the nose forming strips, and a method of fabricating them comprising machining the facial end walls of the abutting blade sections to provide a precise alignment thereof providing a flush joint when the sections are butted together, adhesively bonding the blade sections in abutting relation and permitting the bond to cure, cutting communicating splice receiving slots in the abutting nose forming strips, and inserting adhesively bonding splice inserts which fit the slots in place in the slot.

<CIT> discloses a wind turbine blade with a trailing edge including a radially inboard portion and a radially outboard portion opposite the radially inboard portion. The trailing edge further includes at least one serrated portion extending at least partially between the radially inboard portion and the radially outboard portion. The serrated portion includes at least one substantially acoustically absorbent material.

<CIT> discloses a method of manufacturing a lead edge protective sheath for an airfoil component. The method includes generating a digital model of a lead edge protective sheath for an airfoil component, inputting the digital model into an additive manufacturing machine, and printing, with one or more selected materials, a lead edge protective sheath for an airfoil component based on the digital model.

Other examples of the prior art for a joint area of a rotor blade of a wind turbine and a method for joining a first blade component and a second blade component of a rotor blade are described in <CIT> and <CIT>.

In one aspect as defined in claim <NUM>, the present disclosure is directed to a method for joining a first blade component and a second blade component of a rotor blade together. The method includes printing and depositing, via a computer numeric control (CNC) device, at least one three-dimensional (<NUM>-D) grid structure at a first joint area of the rotor blade. The first joint area contains the first blade component interfacing with the second blade component. The method also includes providing an adhesive at the first joint area and contacting at least a portion of the grid structure. Further, the method includes securing the first blade component and the second blade component together at the first joint area via the adhesive.

In one embodiment, the adhesive may at least partially fill the grid structure. In another embodiment, the first and second blade components may include first and second outer surfaces of the rotor blade, a shear web, and/or a spar cap. Thus, in one embodiment, the method may include placing the first outer surface into a mold of the rotor blade, printing and depositing, via the CNC device, the grid structure(s) onto an inner surface of the first outer surface at the first joint area, wherein the grid structure bonds to the first outer surface as the grid structure is being deposited, placing the second outer surface atop the first outer surface, and securing the first and second outer surfaces together via the adhesive.

According to the invention, the first joint area includes a spar cap/shear web connection, a spar cap/blade shell connection, and/or a blade shell/blade shell connection. More specifically, in certain embodiments, the blade shell/blade shell connection includes a trailing edge and/or a leading edge of the rotor blade.

According to the invention, the method includes printing and depositing, via the CNC device, a first grid structure onto the inner surface of the first outer surface at the first joint area and a second grid structure onto the inner surface of the first outer surface at a different, second joint area. In such embodiments, the method also includes printing and depositing, via the CNC device, the first grid structure onto the inner surface of the first outer surface and spaced apart from the trailing edge of the rotor blade to provide a first gap. In addition, the method further includes printing and depositing, via the CNC device, the second grid structure onto the inner surface of the first outer surface and spaced apart from the leading edge of the rotor blade to provide a second gap.

According to the invention, the method includes filling, at least in part, at least one of the first gap or the second gap with the adhesive. In addition to the adhesive, in certain embodiments, the method may also include forming at least a portion of the grid structure of a foaming agent.

In still further embodiments, the method may include selectively applying cooling air to the grid structure during printing and depositing. In yet another embodiment, the method may also include printing and depositing, via the CNC device, one or more alignment structures into the at least one grid structure.

In additional embodiments, the grid structure(s) may contact the inner surface of the first outer surface and an inner surface of the second outer surface. Thus, in certain embodiments, the grid structure(s) may include a tapered chord-wise cross-section.

In another aspect according to claim <NUM>, the present disclosure is directed to a joint area of a rotor blade of a wind turbine. The joint area includes a first blade component, a second blade component interfacing with the first blade component at a joint, at least one three-dimensional (<NUM>-D) grid structure positioned between the first and second blade components adjacent to the joint, and an adhesive provided between the grid structure and the first and second blade components.

In one embodiment, the first and second blade components of the joint area may include first and second outer surfaces of the rotor blade, a shear web, or a spar cap. In another embodiment, the grid structure(s) may be formed, at least in part, via additive manufacturing. Alternatively, or in addition, the grid structure(s) may be formed, at least in part, of a pre-fabricated honeycomb material. It should be understood that the joint area may further include any of the additional features as described herein.

In yet another non-claimed aspect, the present disclosure is directed to a method for securing a blade add-on component to a rotor blade. The method includes printing and depositing, via a computer numeric control (CNC) device, at least one three-dimensional (<NUM>-D) grid structure to form the blade add-on component. The method also includes placing the blade add-on component onto or within the rotor blade. Further, the method includes providing an adhesive to at least partially fill the grid structure. Moreover, the method includes securing the blade add-on component to the rotor blade via the adhesive.

In one embodiment, the blade add-on component may correspond to a reinforcement structure for a leading edge or a trailing edge, a flatback airfoil corner, or a tip extension. It should be understood that the method may further include any of the additional features and/or steps as described herein.

Generally, the present disclosure is directed to methods for manufacturing grid structures for wind turbine rotor blades using automated deposition of materials via technologies such as <NUM>-D Printing, additive manufacturing, automated fiber deposition, as well as other techniques that utilize CNC control and multiple degrees of freedom to deposit material. As such, the grid structures of the present disclosure are useful for reinforcing a joint area of the rotor blade (i.e. by providing buckling resistance at the joint area). More specifically, the printed structures described herein may contain one or more gaps and may be shaped to fill the space between two laminate surfaces that require bonding. The tight gaps within the printed structure allow for a significantly reduced amount of adhesive to be used and allow the adhesive to flow between the gaps of the printed structure upon closing. Thus, the adhesive flow between the gaps and the reduced amount of adhesive needed substantially reduces the hydraulic pressure needed to close the joint. In addition, the adhesive can form a mechanical lock when cured into the structure to increase bonding strength and reliability compared to an adhesive-only bond. As such, joints of the present disclosure provide a net weight savings as the bulk of the printed structure gaps remains unfilled after closing of the joint.

In addition, the grid structures described herein allow for faster curing adhesives to be used and reduce the overall process cycle time and weight. Moreover, the grid structures of the present disclosure allow for non-destructive testing (NDT) inspection, as the joint areas no longer require foam. Further, the grid structures of the present disclosure can be directly printed to thermoplastic fiberglass skins, thereby providing a more ideal bonding surface. The printed structures of the present disclosure may also simultaneously be used to align components during the bonding process and can be used to fill difficult gaps, such as the space created when using flat pultrusions in spar caps against a curved airfoil surface.

Referring now to the drawings, <FIG> illustrates one embodiment of a wind turbine <NUM> according to the present disclosure. As shown, the wind turbine <NUM> includes a tower <NUM> with a nacelle <NUM> mounted thereon. A plurality of rotor blades <NUM> are mounted to a rotor hub <NUM>, which is in turn connected to a main flange that turns a main rotor shaft. The wind turbine power generation and control components are housed within the nacelle <NUM>. The view of <FIG> is provided for illustrative purposes only to place the present invention in an exemplary field of use. It should be appreciated that the invention is not limited to any particular type of wind turbine configuration. In addition, the present invention is not limited to use with wind turbines, but may be utilized in any application having rotor blades. Further, the methods described herein may also apply to manufacturing any similar structure that benefits from printing a structure directly to skins within a mold before the skins have cooled so as to take advantage of the heat from the skins to provide adequate bonding between the printed structure and the skins. As such, the need for additional adhesive or additional curing is eliminated.

Referring now to <FIG> and <FIG>, various views of a rotor blade <NUM> according to the present disclosure are illustrated. As shown, the illustrated rotor blade <NUM> has a segmented or modular configuration. It should also be understood that the rotor blade <NUM> may include any other suitable configuration now known or later developed in the art. As shown, the modular rotor blade <NUM> includes a main blade structure <NUM> constructed, at least in part, from a thermoset and/or a thermoplastic material and at least one blade segment <NUM> configured with the main blade structure <NUM>. More specifically, as shown, the rotor blade <NUM> includes a plurality of blade segments <NUM>. The blade segment(s) <NUM> may also be constructed, at least in part, from a thermoset and/or a thermoplastic material.

The thermoplastic rotor blade components and/or materials as described herein generally encompass a plastic material or polymer that is reversible in nature. For example, thermoplastic materials typically become pliable or moldable when heated to a certain temperature and returns to a more rigid state upon cooling. Further, thermoplastic materials may include amorphous thermoplastic materials and/or semi-crystalline thermoplastic materials. For example, some amorphous thermoplastic materials may generally include, but are not limited to, styrenes, vinyls, cellulosics, polyesters, acrylics, polysulphones, and/or imides. More specifically, exemplary amorphous thermoplastic materials may include polystyrene, acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), glycolised polyethylene terephthalate (PET-G), polycarbonate, polyvinyl acetate, amorphous polyamide, polyvinyl chlorides (PVC), polyvinylidene chloride, polyurethane, or any other suitable amorphous thermoplastic material. In addition, exemplary semi-crystalline thermoplastic materials may generally include, but are not limited to polyolefins, polyamides, fluropolymer, ethyl-methyl acrylate, polyesters, polycarbonates, and/or acetals. More specifically, exemplary semi-crystalline thermoplastic materials may include polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polypropylene, polyphenyl sulfide, polyethylene, polyamide (nylon), polyetherketone, or any other suitable semi-crystalline thermoplastic material.

Further, the thermoset components and/or materials as described herein generally encompass a plastic material or polymer that is non-reversible in nature. For example, thermoset materials, once cured, cannot be easily remolded or returned to a liquid state. As such, after initial forming, thermoset materials are generally resistant to heat, corrosion, and/or creep. Example thermoset materials may generally include, but are not limited to, some polyesters, some polyurethanes, esters, epoxies, or any other suitable thermoset material.

In addition, as mentioned, the thermoplastic and/or the thermoset material as described herein may optionally be reinforced with a fiber material, including but not limited to glass fibers, carbon fibers, polymer fibers, wood fibers, bamboo fibers, ceramic fibers, nanofibers, metal fibers, or similar or combinations thereof. In addition, the direction of the fibers may include multi-axial, unidirectional, biaxial, triaxial, or any other another suitable direction and/or combinations thereof. Further, the fiber content may vary depending on the stiffness required in the corresponding blade component, the region or location of the blade component in the rotor blade <NUM>, and/or the desired weldability of the component.

More specifically, as shown, the main blade structure <NUM> may include any one of or a combination of the following: a pre-formed blade root section <NUM>, a pre-formed blade tip section <NUM>, one or more one or more continuous spar caps <NUM>, <NUM>, <NUM>, <NUM>, one or more shear webs <NUM> (<FIG>), an additional structural component <NUM> (such as an additional spar cap) secured to the blade root section <NUM>, and/or any other suitable structural component of the rotor blade <NUM>. Further, the blade root section <NUM> is configured to be mounted or otherwise secured to the rotor <NUM> (<FIG>). In addition, as shown in <FIG>, the rotor blade <NUM> defines a span <NUM> that is equal to the total length between the blade root section <NUM> and the blade tip section <NUM>. As shown in <FIG> and <FIG>, the rotor blade <NUM> also defines a chord <NUM> that is equal to the total length between a leading edge <NUM> of the rotor blade <NUM> and a trailing edge <NUM> of the rotor blade <NUM>. As is generally understood, the chord <NUM> may generally vary in length with respect to the span <NUM> as the rotor blade <NUM> extends from the blade root section <NUM> to the blade tip section <NUM>.

Referring particularly to <FIG>, any number of blade segments <NUM> having any suitable size and/or shape may be generally arranged between the blade root section <NUM> and the blade tip section <NUM> along a longitudinal axis <NUM> in a generally span-wise direction. Thus, the blade segments <NUM> generally serve as the outer casing/covering of the rotor blade <NUM> and may define a substantially aerodynamic profile that includes a pressure side surface <NUM> and a suction side surface <NUM> (<FIG> and <FIG>), such as by defining a symmetrical or cambered airfoil-shaped cross-section. In additional embodiments, it should be understood that the blade segment portion of the blade <NUM> may include any combination of the segments described herein and are not limited to the embodiment as depicted. In addition, the blade segments <NUM> may be constructed of any suitable materials, including but not limited to a thermoset material or a thermoplastic material optionally reinforced with one or more fiber materials. More specifically, in certain embodiments, the blade segments <NUM> may include pressure and/or suction side segments <NUM>, <NUM> (<FIG> and <FIG>) and/or leading and/or trailing edge segments <NUM>, <NUM> (<FIG>), or similar.

More specifically, as shown in <FIG>, the leading edge segments <NUM> may have a forward pressure side surface <NUM> and a forward suction side surface <NUM>. Similarly, as shown in <FIG>, each of the trailing edge segments <NUM> may have an aft pressure side surface <NUM> and an aft suction side surface <NUM>. Thus, the forward pressure side surface <NUM> of the leading edge segment <NUM> and the aft pressure side surface <NUM> of the trailing edge segment <NUM> generally define a pressure side surface of the rotor blade <NUM>. Similarly, the forward suction side surface <NUM> of the leading edge segment <NUM> and the aft suction side surface <NUM> of the trailing edge segment <NUM> generally define a suction side surface of the rotor blade <NUM>. In addition, as particularly shown in <FIG>, the leading edge segment(s) <NUM> and the trailing edge segment(s) <NUM> may be joined at a pressure side seam <NUM> and a suction side seam <NUM>. For example, the blade segments <NUM>, <NUM> may be configured to overlap at the pressure side seam <NUM> and/or the suction side seam <NUM>. Further, as shown in <FIG>, adjacent blade segments <NUM> may be configured to overlap at a seam <NUM>. Thus, where the blade segments <NUM> are constructed at least partially of a thermoplastic material, adjacent blade segments <NUM> can be welded together along the seams <NUM>, <NUM>, <NUM>, which will be discussed in more detail herein. Alternatively, in certain embodiments, the various segments of the rotor blade <NUM> may be secured together via an adhesive (or mechanical fasteners) configured between the overlapping leading and trailing edge segments <NUM>, <NUM> and/or the overlapping adjacent leading or trailing edge segments <NUM>, <NUM>.

In specific embodiments, as shown in <FIG> and <FIG>, the blade root section <NUM> may include one or more longitudinally extending spar caps <NUM>, <NUM> infused therewith. Similarly, the blade tip section <NUM> may include one or more longitudinally extending spar caps <NUM>, <NUM> infused therewith. More specifically, as shown, the spar caps <NUM>, <NUM>, <NUM>, <NUM> may be configured to be engaged against opposing inner surfaces of the blade segments <NUM> of the rotor blade <NUM>. Further, the blade root spar caps <NUM>, <NUM> may be configured to align with the blade tip spar caps <NUM>, <NUM>. Thus, the spar caps <NUM>, <NUM>, <NUM>, <NUM> may generally be designed to control the bending stresses and/or other loads acting on the rotor blade <NUM> in a generally span-wise direction (a direction parallel to the span <NUM> of the rotor blade <NUM>) during operation of a wind turbine <NUM>. In addition, the spar caps <NUM>, <NUM>, <NUM>, <NUM> may be designed to withstand the span-wise compression occurring during operation of the wind turbine <NUM>. Further, the spar cap(s) <NUM>, <NUM>, <NUM>, <NUM> may be configured to extend from the blade root section <NUM> to the blade tip section <NUM> or a portion thereof. Thus, in certain embodiments, the blade root section <NUM> and the blade tip section <NUM> may be joined together via their respective spar caps <NUM>, <NUM>, <NUM>, <NUM>.

In addition, the spar caps <NUM>, <NUM>, <NUM>, <NUM> may be constructed of any suitable materials, e.g. a thermoplastic or thermoset material or combinations thereof. Further, the spar caps <NUM>, <NUM>, <NUM>, <NUM> may be pultruded from thermoplastic or thermoset resins. As used herein, the terms "pultruded," "pultrusions," or similar generally encompass reinforced materials (e.g. fibers or woven or braided strands) that are impregnated with a resin and pulled through a stationary die such that the resin cures or undergoes polymerization. As such, the process of manufacturing pultruded members is typically characterized by a continuous process of composite materials that produces composite parts having a constant cross-section. Thus, the pre-cured composite materials may include pultrusions constructed of reinforced thermoset or thermoplastic materials. Further, the spar caps <NUM>, <NUM>, <NUM>, <NUM> may be formed of the same pre-cured composites or different pre-cured composites. In addition, the pultruded components may be produced from rovings, which generally encompass long and narrow bundles of fibers that are not combined until joined by a cured resin.

Referring to <FIG>, one or more shear webs <NUM> may be configured between the one or more spar caps <NUM>, <NUM>, <NUM>, <NUM>. More particularly, the shear web(s) <NUM> may be configured to increase the rigidity in the blade root section <NUM> and/or the blade tip section <NUM>. Further, the shear web(s) <NUM> may be configured to close out the blade root section <NUM>.

Referring now to <FIG>, the present disclosure is directed to methods for joining first and second blade components the rotor blade <NUM> together at a joint, e.g. via <NUM>-D printing. For example, in one embodiment, the first and second blade components may include the pressure and/or suction side surfaces <NUM>, <NUM> of the rotor blade <NUM>, the shear web <NUM>, the spar cap <NUM>, <NUM>, <NUM>, <NUM> and/or combinations thereof. Thus, the methods of the present disclosure can be used in a variety of joint areas or connections, including but not limited to a spar cap/shear web connection, a spar cap/blade shell connection, and/or a blade shell/blade shell connection. More specifically, in certain embodiments, the blade shell/blade shell connection may include the trailing edge <NUM> and/or the leading edge <NUM> of the rotor blade <NUM>. Thus, the illustrated embodiment of <FIG> illustrates the process of forming first and second joint areas <NUM> and <NUM> between the pressure and/or suction side surfaces <NUM>, <NUM> (i.e. at the trailing and leading edges <NUM>, <NUM>).

As used herein, <NUM>-D printing is generally understood to encompass processes used to synthesize three-dimensional objects in which successive layers of material are formed under computer control to create the objects. As such, objects of almost any size and/or shape can be produced from digital model data. It should further be understood that the methods of the present disclosure are not limited to <NUM>-D printing, but rather, may also encompass more than three degrees of freedom such that the printing techniques are not limited to printing stacked two-dimensional layers, but are also capable of printing curved shapes.

Referring particularly to <FIG>, one embodiment of the method includes placing a mold <NUM> of the rotor blade <NUM> (or one of the blade segments <NUM>) relative to a CNC device <NUM>. More specifically, as shown in the illustrated embodiment, the method may include placing the mold <NUM> into a bed <NUM> of the CNC device <NUM>. Alternatively, the method may include placing the mold <NUM> under the CNC device <NUM> or adjacent the CNC device <NUM>.

Further, as shown, the method of the present disclosure further includes forming one or more fiber-reinforced outer skin surfaces <NUM> in the mold <NUM> of the rotor blade <NUM>. In certain embodiments, the outer skin surface(s) <NUM> (which form the pressure and/or suction side surfaces <NUM>, <NUM>) may include one or more continuous, multi-axial (e.g. biaxial) fiber-reinforced thermoplastic or thermoset outer skins. Further, in particular embodiments, the method of forming the fiber-reinforced outer skin surfaces <NUM> may include at least one of injection molding, <NUM>-D printing, <NUM>-D pultrusion, <NUM>-D pultrusion, thermoforming, vacuum forming, pressure forming, bladder forming, automated fiber deposition, automated fiber tape deposition, or vacuum infusion.

For example, in one embodiment, a thermoset material may be infused into the fiber material on the mold <NUM> to form the outer skin surface <NUM> using vacuum infusion. As such, the vacuum bag is removed after curing and the grid structures <NUM>, <NUM> described herein can then be printed onto the inner surface of the outer skin surfaces <NUM>. Alternatively, the vacuum bag may be left in place after curing. In such embodiments, the vacuum bag material can be chosen such that the material would not easily release from the cured thermoset fiber material. Such materials, for example, may include a thermoplastic material such as polymethyl methacrylate (PMMA) or polycarbonate film. Thus, the thermoplastic film that is left in place allows for bonding of thermoplastic grid structures <NUM> to the thermoset skins with the film in between.

In still further embodiments, the outer skin surface(s) <NUM> may be formed of a reinforced thermoplastic resin with the grid structures <NUM>, <NUM> being formed of a thermoset-based resin with optional fiber reinforcement. In such embodiments, depending on the thermoset chemistry involved - the grid structures <NUM>, <NUM> may be printed to the outer skin surfaces <NUM> while the surfaces <NUM> are still hot, warm, partially cooled, or completely cooled.

In addition, the outer skin surfaces <NUM> may be further treated to promote bonding between the outer skin surfaces s56 and the grid structure <NUM>, <NUM>. More specifically, in certain embodiments, the outer skin surfaces <NUM> may be treated using flame treating, plasma treating, chemical treating, chemical etching, mechanical abrading, embossing, elevating a temperature of at least areas to be printed on the outer skin surfaces <NUM>, and/or any other suitable treatment method to promote said bonding. In additional embodiments, the method may include forming the outer skin surfaces <NUM> with more (or even less) matrix resin material on the inside surface to promote said bonding. In additional embodiments, the method may include varying the outer skin thickness and/or fiber content, as well as the fiber orientation.

In addition, as shown, the outer skin surface(s) <NUM> of the rotor blade <NUM> may be curved. In such embodiments, the method may include forming the curvature of the outer skin surfaces <NUM>. Such forming may include providing one or more generally flat fiber-reinforced outer skin surfaces, forcing the outer skin surfaces <NUM> into a desired shape corresponding to a desired contour, and maintaining the outer skin surfaces <NUM> in the desired shape during printing and depositing. As such, the outer skin surfaces <NUM> generally retain their desired shape when the outer skin surfaces <NUM> and the grid structures <NUM>, <NUM> printed thereto are released. In addition, the CNC device <NUM> may be adapted to include a tooling path that follows the contour of the rotor blade <NUM>.

Thus, as shown in <FIG>, one embodiment of the method includes printing and depositing the grid structure <NUM> directly to the inner surface of the outer skin surface(s) <NUM> via the CNC device <NUM>. More specifically, as shown, the CNC device <NUM> is configured to print and deposit, at least, a first the grid structure <NUM> onto the inner surface of the first outer surface at the first joint area <NUM> of the rotor blade <NUM>. In addition, as shown, the CNC device <NUM> may print and deposit a second grid structure <NUM> onto the inner surface of the first outer surface <NUM> at a different, second joint area <NUM>.

It should be understood that any suitable shape of grid structures <NUM>, <NUM> described herein can be printed and deposited as desired. As such, in certain embodiments, the grid structures <NUM>, <NUM> may bond to the outer skin(s) <NUM> as the grid structures <NUM>, <NUM> are being deposited, which reduces the amount of adhesive and/or curing time needed for the first and second joint areas <NUM>, <NUM>, respectively. For example, as shown in <FIG>, various embodiments of different shapes and sizes of the grid structure <NUM> at the trailing edge <NUM> are illustrated. More specifically, as shown in the illustrated embodiment, the grid structure <NUM> may have a size ranging from about <NUM> millimeters (mm) to about <NUM>. It should be understood, however, that the size of the grid structures <NUM>, <NUM> may depend on the size and shape of the rotor blade <NUM>. Further, as shown in <FIG>, the grid structure <NUM> may extend from the adhesive <NUM> at the trailing edge <NUM> up to, e.g. <NUM>% chord length. Alternatively, as shown in <FIG>, the grid structure <NUM> may be spaced apart from the adhesive <NUM> at the trailing edge <NUM> so as to minimize the weight at the joint area <NUM>.

For example, in one embodiment, the CNC device <NUM> is configured to print and deposit the grid structures <NUM>, <NUM> after the formed skin surface <NUM> reaches a desired state that enables bonding of the grid structures <NUM>, <NUM> thereto, i.e. based on one or more parameters of temperature, time, and/or hardness. Therefore, in certain embodiments, wherein the skin surfaces <NUM> and grid structures <NUM>, <NUM> are formed of a thermoplastic matrix, the CNC device <NUM> may immediately print the grid structures <NUM>, <NUM> thereto as the forming temperature of the skin surface(s) <NUM> and the desired printing temperature to enable thermoplastic welding/bonding can be the same).

More specifically, in particular embodiments, before the skin surface(s) <NUM> have cooled from forming, (i.e. while the skins are still hot or warm), the CNC device <NUM> is configured to print and deposit the grid structures <NUM>, <NUM> onto the inner surface of the outer skin surfaces <NUM>. For example, in one embodiment, the CNC device <NUM> is configured to print and deposit the grid structures <NUM>, <NUM> onto the inner surface of the outer skin surfaces <NUM> before the surfaces <NUM> have completely cooled. In addition, in another embodiment, the CNC device <NUM> is configured to print and deposit the grid structures <NUM>, <NUM> onto the inner surface of the outer skin surfaces <NUM> when the surfaces <NUM> have partially cooled. Thus, suitable materials for the grid structures <NUM>, <NUM> and the outer skin surfaces <NUM> can be chosen such that the grid structures <NUM>, <NUM> bonds to the outer skin surfaces <NUM> during deposition. Accordingly, the grid structures <NUM>, <NUM> described herein may be printed using the same materials or different materials.

It should be understood that the grid structures <NUM>, <NUM> of the present disclosure may include varying shapes and/or designs (e.g. materials, width, height, thickness, shapes, etc., or combinations thereof). As such, the grid structures <NUM>, <NUM> may define any suitable shape so as to form any suitable structure that can be used at any joint connection within the rotor blade <NUM> such that adhesives can be reduced in such joints. Thus, the CNC device <NUM> can be designed having one or more extruders <NUM> that generate any suitable thickness or width so as to disperse a desired amount of resin material to create the grid structures <NUM>, <NUM> with varying heights and/or thicknesses. For example, many rotor blade joints include tight angles and/or tapered cross-sections that are conventionally filled with adhesives. Thus, as shown particularly in <FIG>, the grid structure(s) <NUM>, <NUM> of the present disclosure can be printed to contact both of the inner surfaces of the pressure and/or suction side surfaces <NUM>, <NUM>. Thus, in such embodiments, the grid structure(s) <NUM>, <NUM> may include a tapered chord-wise cross-section.

In yet another embodiment, the CNC device <NUM> may also print and deposit one or more alignment structures <NUM> into the grid structure(s) <NUM>, <NUM>. For example, as shown in <FIG>, the grid structure(s) <NUM>, <NUM> may include may include an alignment structure <NUM> that is printed along with the grid structure(s) <NUM>, <NUM> for assisting in aligning adjacent rotor blade components (such as printed reinforcement grids of the pressure and/or suction side surfaces <NUM>, <NUM>).

When the grid structures <NUM>, <NUM> are printed using extruded thermoplastics with tighter gaps, the structures <NUM>, <NUM> can retain heat as the printed structure gets taller. Additional heat can be further retained as the shape of many rotor blade joints are tapered or angled, thereby requiring grid structures <NUM>, <NUM> within a tapered or angled cross-section. As such, the printed layer times get shorter as the part is built. As a result, taller structures and those portions with shorter layer times (i.e. the time it takes to print a layer before starting the next layer) can begin to sag and puddle as there is not enough cooling time to sufficiently solidify the previous layer. Thus, the method of the present disclosure is configured to slow down the print speeds as needed, alter the formulation of the resin system to use a faster solidifying resin matrix (e.g. a more semi crystalline/less amorphous formulation), and/or selectively apply cooling air to the grid structures <NUM>, <NUM> during printing and depositing. For example, in one embodiment, as shown in <FIG>, the CNC device <NUM> may include one or more cooling fans <NUM> or cooling air nozzles that selectively turn on as needed to cool down the grid structures <NUM>, <NUM>.

In addition to additive manufacturing, the grid structures <NUM>, <NUM> of the present disclosure may also be formed, at least in part, of one or more pre-fabricated sections of a honeycomb material. For example, in one embodiment, honeycomb prefabricated material can be CNC machined to fit the desired shape needed at the joint and adhesive can be applied to both inner surfaces of the outer skin surfaces <NUM> to bond the honeycomb material in place. In another embodiment, a thermoplastic honeycomb material may be crushed into shape under pressure and/or heated along with adhesives.

After the grid structures <NUM>, <NUM> are printed on the outer skin surface <NUM>, as shown in <FIG>, the method may include providing an adhesive <NUM> at the first joint area <NUM> and/or the second joint area <NUM>, e.g. to at least partially fill the grid structures <NUM>, <NUM>. Thus, the method also includes placing the second outer surface atop the first outer surface and the printed grid structures <NUM>, <NUM> and securing the first and second outer skin surfaces <NUM>, <NUM> together at first and second joints <NUM>, <NUM>, respectively, via the adhesive <NUM>. Thus, as shown <FIG>, the first joint <NUM> contains the trailing edge <NUM> of the rotor blade <NUM>, where the pressure and suction side surfaces <NUM>, <NUM> of the rotor blade <NUM> are secured together. Similarly, as shown, the second joint <NUM> contains the leading edge <NUM> of the rotor blade <NUM>, also where the pressure and suction side surfaces <NUM>, <NUM> of the rotor blade <NUM> are secured together.

In such embodiments, as shown in <FIG>, <FIG>, the first grid structure <NUM> may be spaced apart from the trailing edge <NUM> of the rotor blade <NUM> to provide a first gap <NUM>. More specifically, as shown in <FIG>, the first gap <NUM> may extend from about <NUM>% to about <NUM>% as an example of the chord-wise length of the rotor blade <NUM>. It should be understood that the first gap <NUM> may include any suitable chord-wise length that is sufficient for adhesion of the pressure and suction side surfaces <NUM>, <NUM>. In addition, as shown in <FIG>, the second grid structure <NUM> may also be spaced apart from the leading edge <NUM> of the rotor blade <NUM> to provide a second gap <NUM>. Similarly, the second gap <NUM> may extend from about <NUM>% to about <NUM>% as an example of the chord-wise length of the rotor blade <NUM>. Further, it should be understood that the second gap <NUM> may include any suitable chord-wise length that is sufficient for adhesion of the pressure and suction side surfaces <NUM>, <NUM>.

Thus, the method may also include filling, at least in part, the first and/or second gaps <NUM>, <NUM> with the adhesive <NUM>. For example, as shown in <FIG> and <FIG>, the first gap <NUM> may be completely filled with adhesive <NUM>. Alternatively, as shown in <FIG>, only a portion of the first gap <NUM> may be filled with adhesive <NUM>. In addition, as shown in <FIG> and <FIG>, the second gap <NUM> may be left primarily free of adhesive <NUM>. Alternatively, the second gap <NUM> may be partially or completely filled with adhesive <NUM>.

In another embodiment, the method may include forming at least a portion of the grid structure <NUM> of a foaming agent <NUM>. For example, as shown in <FIG>, a portion of the grid structure <NUM> at the first joint area <NUM> is formed of the foaming agent <NUM> to further reduce the weight of the structure <NUM> and therefore the overall rotor blade <NUM>.

The methods of the present disclosure can also be useful for certain types of blade add-on components, where certain aerodynamic features are desired to be added to the exterior surface of a rotor blade either after production and/or to existing rotor blades in the field. Thus, referring now to <FIG>, a flow diagram of one embodiment of a method <NUM> for securing a blade add-on component to a rotor blade <NUM> is illustrated. As shown at <NUM>, the method <NUM> includes printing and depositing, via the CNC device <NUM>, at least one three-dimensional (<NUM>-D) grid structure to form the blade add-on component. As shown at <NUM>, the method <NUM> includes placing the blade add-on component onto or within the rotor blade. As shown at <NUM>, the method <NUM> includes providing an adhesive to at least partially fill the grid structure. As shown at <NUM>, the method <NUM> includes securing the blade add-on component to the rotor blade via the adhesive.

Examples of the blade add-on component may include flatback airfoil corner sections, tip extensions (i.e. a grid structure used to fill thin sections between a sock tip and the rotor blade <NUM>, and allow for bonding using this grid technique), or a reinforcement structure for a leading edge or a trailing edge.

Claim 1:
A method (<NUM>) for joining a first blade component and a second blade component of a rotor blade (<NUM>) together, the method (<NUM>) comprising:
printing and depositing, via a computer numeric control (CNC) device (<NUM>), at least one three-dimensional (<NUM>-D) grid structure (<NUM>, <NUM>) at a first joint area (<NUM>) of the rotor blade (<NUM>), the first joint area (<NUM>) containing the first blade component interfacing with the second blade component;
providing an adhesive (<NUM>) at the first joint area (<NUM>) and contacting at least a portion of the grid structure (<NUM>, <NUM>), wherein the first joint area (<NUM>) comprises at least one of a spar cap/shear web connection, a spar cap/blade shell connection, or a blade shell/blade shell connection, the blade shell/blade shell connection comprising at least one of a trailing edge of the rotor blade (<NUM>) or a leading edge of the rotor blade (<NUM>);
securing the first blade component and the second blade component together at the first joint area (<NUM>) via the adhesive (<NUM>); the method further comprising
printing and depositing, via the CNC device (<NUM>), a first grid structure (<NUM>, <NUM>) onto an inner surface of a first outer surface of the rotor blade at the first joint area (<NUM>) and spaced apart from the trailing edge of the rotor blade (<NUM>) to provide a first gap, and
printing and depositing, via the CNC device (<NUM>) a second grid structure (<NUM>, <NUM>) onto the inner surface of the first outer surface at a different, second joint area (<NUM>) and spaced apart from the leading edge of the rotor blade (<NUM>) to provide a second gap; and
filling, at least in part, at least one of the first gap or the second gap with the adhesive (<NUM>).