Method for connecting blade components of rotor blades using a printed grid structure

Abstract

A method for joining a first blade member and a second blade member of a rotor blade includes printing and depositing at least one three-dimensional (3-D) grid structure at a first joint region of the rotor blade via a computer numerical control (CNC) device. The first joint region includes the first blade member that mates with the second blade member. The method further includes providing an adhesive at the first joint region to at least partially fill the grid structure. Additionally, the method includes securing the first blade member and the second blade member together at the first joint region via the adhesive.

Description

Technical Field

[0001] The present disclosure generally relates to wind turbine rotor blades, and more particularly to methods for joining blade components of a rotor blade using a printed grid structure. Background Art

[0002] Wind power is considered to be one of the cleanest and most environmentally friendly energy sources currently available, and wind turbines have received increased attention in this regard. Modern wind turbines typically include a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades use the known foil principle to capture the kinetic energy of the wind. The rotor blades transfer the kinetic energy in the form of rotational energy to rotate a shaft that couples the rotor blades to the gearbox (or directly to the generator if no gearbox is used). The generator then converts the mechanical energy into electrical energy, which can be deployed to the utility grid.

[0003] The rotor blade generally includes a suction side shell and a pressure side shell, which are typically formed using a molding process and are joined together at a bond line along the leading and trailing edges of the blade. In addition, the pressure and suction shells are relatively lightweight and have structural properties (e.g., stiffness, buckling resistance, and strength) that are not configured to withstand the bending moments and other loads applied to the rotor blade during operation. Thus, to increase the stiffness, buckling resistance, and strength of the rotor blade, the main shells are typically reinforced using one or more structural members (e.g., opposing spar caps with shear webs constructed therebetween) that engage the inner pressure side and suction side surfaces of the shell halves.

[0004] In addition, conventional rotor blades require a significant amount of bonding paste to provide structure at various blade joints (e.g., at the leading or trailing edge of the rotor blade) to prevent local buckling of the suction side and pressure side shells. Due to the complex geometries near these joint regions, it is generally difficult to provide this structure in other ways that are lighter than the bonding paste. Thus, conventional rotor blades typically use an excessive amount of paste for the structure required at the joints. However, such excessive paste is expensive, heavy, and can limit the types of adhesives that can be used. For example, a heavy and thick adhesive section containing a fast-curing adhesive with a highly exothermic reaction can generate excessive heat and damage the surrounding materials, creating a safety hazard.

[0005] In view of the foregoing, there is a continuing search in the art for improved methods for joining blade components of a rotor blade using less adhesive. Summary of the Invention

[0006] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned by practice of the invention.

[0007] In one aspect, the present disclosure relates to a method for joining a first blade member and a second blade member of a rotor blade. The method includes printing and depositing at least one three-dimensional (3-D) grid structure at a first joint region of the rotor blade via a computer numerical control (CNC) device. The first joint region includes the first blade member that mates with the second blade member. The method further includes providing an adhesive at the first joint region and contacting at least a portion of the grid structure. Additionally, the method includes securing the first blade member and the second blade member together at the first joint region via the adhesive.

[0008] In one embodiment, the adhesive may at least partially fill the grid structure. In another embodiment, the first blade member and the second blade member may include a first outer surface and a second outer surface of the rotor blade, shear webs, and / or spar caps. Thus, in one embodiment, the method may include placing the first outer surface into a mold of the rotor blade, printing and depositing the grid structure at the first joint region onto an inner surface of the first outer surface via the CNC device, where the grid structure bonds to the first outer surface upon deposition of the grid structure, placing the second outer surface on top of the first outer surface, and securing the first outer surface and the second outer surface together via the adhesive.

[0009] In additional embodiments, the first joint region may include a spar cap / shear web connection, a spar cap / blade shell connection, and / or a blade shell / blade shell connection. More particularly, in certain embodiments, the blade shell / blade shell connection may include a trailing edge and / or a leading edge of the rotor blade.

[0010] In further embodiments, the method may include printing and depositing a first grid structure onto an inner surface of the first outer surface at the first joint region via the CNC device and printing and depositing a second grid structure onto the inner surface of the first outer surface at a different second joint region. In such embodiments, the method may further include printing and depositing the first grid structure onto the inner surface of the first outer surface via the CNC device and spaced apart from the trailing edge of the rotor blade to provide a first gap. Additionally, in some embodiments, the method may further include printing and depositing the second grid structure onto the inner surface of the first outer surface via the CNC device and spaced apart from the leading edge of the rotor blade to provide a second gap.

[0011] In another embodiment, the method may include at least partially filling at least one of the first gap or the second gap with the adhesive. In addition to the adhesive, in some embodiments, the method may further include forming at least a portion of the grid structure as a foaming agent.

[0012] In some further embodiments, the method may include selectively applying cooling air to the grid structure during printing and deposition. In yet another embodiment, the method may further include printing and depositing one or more alignment structures into at least one grid structure via a CNC device.

[0013] In additional embodiments, the grid structure may contact the inner surface of the first outer surface and the inner surface of the second outer surface. Thus, in certain embodiments, the grid structure may include a tapered cross-section along the chord of the airfoil.

[0014] In another aspect, the present disclosure relates to a joint region of a rotor blade of a wind turbine. The joint region includes a first blade member, a second blade member mating with the first blade member at the joint, at least one three-dimensional (3-D) grid structure positioned between the first blade member and the second blade member adjacent to the joint, and an adhesive provided between the grid structure and the first blade member and the second blade member.

[0015] In one embodiment, the first blade member and the second blade member of the joint region may include the first outer surface and the second outer surface of the rotor blade, a shear web, or a spar cap. In another embodiment, the grid structure may be formed at least in part via additive manufacturing. Alternatively or additionally, the grid structure may be formed at least in part from prefabricated honeycomb material. It should be understood that the joint region may also include any of the additional features described herein.

[0016] In yet another aspect, the present disclosure relates to a method for attaching a blade attachment member to a rotor blade. The method includes printing and depositing at least one three-dimensional (3-D) grid structure via a computer numerical control (CNC) device to form a blade attachment member. The method further includes placing the blade attachment member onto or within the rotor blade. Additionally, the method includes providing an adhesive to at least partially fill the grid structure. Moreover, the method includes attaching the blade attachment member to the rotor blade via the adhesive.

[0017] In one embodiment, the blade attachment member 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 also include any of the additional features and / or steps described herein.

[0018] These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The complete and enabling disclosure of the present invention, including its best mode, for a person of ordinary skill in the art is set forth in the specification, with reference to the drawings, in which:

[0020] Figure 1 A perspective view of a wind turbine according to an embodiment of the present disclosure is shown;

[0021] Figure 2 A perspective view of a rotor blade of a wind turbine according to an embodiment of the present disclosure is shown;

[0022] Figure 3 Shows Figure 2 An exploded view of a modular rotor blade;

[0023] Figure 4 A cross-sectional view of a leading edge segment of a modular rotor blade according to an embodiment of the present disclosure is shown;

[0024] Figure 5 A cross-sectional view of a trailing edge segment of a modular rotor blade according to an embodiment of the present disclosure is shown;

[0025] Figure 6 Shows according to the present disclosure Figure 2 A cross-sectional view of a modular rotor blade;

[0026] Figure 7 Shows according to the present disclosure Figure 2 A cross-sectional view of a modular rotor blade;

[0027] Figure 8 A side perspective view of an embodiment of a mold for a rotor blade placed within a bed of a 3D printer is shown, particularly showing an outer skin surface placed within the mold according to the present disclosure;

[0028] Figure 9 A side perspective view of an embodiment of a mold for a rotor blade placed within a bed of a 3D printer is shown, particularly showing an outer skin surface with a plurality of grid structures printed thereon placed within the mold according to the present disclosure;

[0029] Figure 10 A cross-sectional view of an embodiment of a rotor blade according to the present disclosure is shown, the rotor blade having a plurality of grid structures printed at different joint regions of the rotor blade;

[0030] Figure 11 Shows Figure 10 A detailed cross-sectional view of the rotor blade at the trailing edge joint;

[0031] Figure 12 Shows Figure 10Detailed cross-sectional view of a rotor blade at the leading edge joint;

[0032] Figure 13 Detailed cross-sectional view showing an embodiment of the trailing edge joint region of a rotor blade incorporating a printed grid structure according to the present disclosure;

[0033] Figure 14 Detailed cross-sectional view showing another embodiment of the trailing edge joint region of a rotor blade incorporating a printed grid structure according to the present disclosure; and

[0034] Figure 15 Flowchart showing an embodiment of a method for attaching a blade attachment member to a rotor blade according to the present disclosure. DETAILED DESCRIPTION

[0035] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the figures. Each example is provided by way of explanation of the invention, and not as a limitation thereof. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For example, features shown or described as part of one embodiment can be used with another embodiment to yield yet another embodiment. Accordingly, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.

[0036] Generally, the present disclosure relates to methods for manufacturing grid structures for wind turbine rotor blades using automated deposition of materials via techniques such as 3-D printing, additive manufacturing, automated fiber placement, and other techniques that use CNC control and multiple degrees of freedom to deposit materials. Thus, the grid structures of the present disclosure are useful for strengthening the joint regions of rotor blades (i.e., by providing buckling resistance at the joint regions). More particularly, the printed structures described herein can include one or more gaps and can be shaped to fill the space between two laminated surfaces that need to be joined. The tight gaps within the printed structure allow for a significant reduction in the amount of adhesive used and allow the adhesive to flow between the gaps of the printed structure when closed. Thus, the adhesive flow between the gaps and the reduced amount of adhesive required considerably reduce the hydraulic pressure required to close the joint. Additionally, the adhesive can form a mechanical lock when cured into the structure, enhancing the bond strength and reliability compared to a bond with only adhesive. Thus, the joints of the present disclosure provide a net weight savings since a large number of the printed structure gaps remain unfilled after the joint is closed.

[0037] Additionally, the grid structures described herein allow for the use of faster curing adhesives, and reduce overall processing cycle time and weight. Also, since the joint areas no longer require foam, the grid structures of the present disclosure allow for non-destructive testing (NDT) inspections. Further, the grid structures of the present disclosure can be printed directly onto a thermoplastic fiberglass skin, thereby providing a more desirable bonding surface. The printed structures of the present disclosure can also 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 against a curved airfoil surface in a spar cap.

[0038] Referring now to the figures, Figure 1 there is shown an embodiment of a wind turbine 10 in accordance with the present disclosure. As shown, the wind turbine 10 includes a tower 12 with a nacelle 14 mounted thereon. A plurality of rotor blades 16 are mounted to a rotor hub 18 which in turn is connected to a main flange that rotates a main rotor shaft. Wind turbine power generation and control components are housed within the nacelle 14. Figure 1 The views are provided for illustrative purposes only to place the invention in an exemplary field of use. It should be understood that the invention is not limited to any particular type of wind turbine configuration. Additionally, the invention is not limited for use with wind turbines, but can be used in any application having rotor blades. Further, the methods described herein can also be applied to manufacturing any similar structure that benefits from printing the structure directly into the skin within a mold prior to skin cooling in order to utilize the heat from the skin to provide sufficient bonding between the printed structure and the skin. Thus, the need for additional adhesives or additional curing is eliminated.

[0039] Referring now to Figure 2 and Figure 3 there are shown various views of a rotor blade 16 in accordance with the present disclosure. As shown, the rotor blade 16 shown has a segmented or modular construction. It should also be understood that the rotor blade 16 can include any other suitable construction now known or later developed in the art. As shown, the modular rotor blade 16 includes a main blade structure 15 at least partially composed of a thermoset and / or thermoplastic material and at least one blade segment 21 configured with the main blade structure 15. More particularly, as shown, the rotor blade 16 includes a plurality of blade segments 21. The blade segments 21 can also be at least partially composed of a thermoset and / or thermoplastic material.

[0040] The thermoplastic rotor blade components and / or materials described herein generally comprise plastic materials or polymers that are reversible in nature. For example, thermoplastic materials typically become pliable or moldable when heated to a certain temperature and return to a more rigid state when cooled. Additionally, thermoplastic materials can include amorphous thermoplastic materials and / or semi-crystalline thermoplastic materials. For example, some amorphous thermoplastic materials can generally include, but are not limited to, styrene, vinyl, cellulose, polyester, acrylic, polysulfone, and / or imide. More particularly, exemplary amorphous thermoplastic materials can include polystyrene, acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), glycolised polyethylene terephthalate (PET-G), polycarbonate, polyvinyl acetate, amorphous polyamide, polyvinyl chloride (PVC), polyvinylidene chloride, polyurethane, or any other suitable amorphous thermoplastic material. Additionally, exemplary semi-crystalline thermoplastic materials can generally include, but are not limited to, polyolefins, polyamides, fluoropolymers, ethyl acrylate, polyester, polycarbonate, and / or acetal. More particularly, exemplary semi-crystalline thermoplastic materials can include polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polypropylene, polyphenylene sulfide, polyethylene, polyamide (nylon), polyether ketone, or any other suitable semi-crystalline thermoplastic material.

[0041] Furthermore, the thermoset components and / or materials described herein generally comprise plastic materials or polymers that are irreversible in nature. For example, once cured, thermoset materials cannot be easily remolded or returned to a liquid state. Thus, after initial formation, thermoset materials are generally heat-resistant, corrosion-resistant, and / or creep-resistant. Exemplary thermoset materials can generally include, but are not limited to, some polyesters, some polyurethanes, esters, epoxy resins, or any other suitable thermoset materials.

[0042] Additionally, as mentioned, the thermoplastic and / or thermoset materials described herein can optionally be reinforced with fiber materials, which include, but are not limited to, glass fibers, carbon fibers, polymer fibers, wood fibers, bamboo fibers, ceramic fibers, nanofibers, metal fibers, or the like or combinations thereof. Additionally, the orientation of the fibers can include multi-axial, unidirectional, bi-axial, tri-axial, or any other another suitable orientation and / or combinations thereof. Furthermore, depending on the stiffness required in the corresponding blade component, the region or location of the blade component within the rotor blade 16, and / or the desired weldability of the component, the fiber content can vary.

[0043] More particularly, as shown, the main blade structure 15 can include any one or combination of the following: a preformed blade root section 20, a preformed blade tip section 22, one or more continuous spar caps 48, 50, 51, 53, one or more shear webs 35( Figures 6 - 7), an additional structural member 52 (such as an additional spar cap) fixed to the blade root section 20, and / or any other suitable structural member of the rotor blade 16. In addition, the blade root section 20 is configured to be mounted or otherwise fixed to the rotor 18( Figure 1 ). Additionally, as Figure 2 shown, the rotor blade 16 defines a span 23, and the span 23 is equal to the total length between the blade root section 20 and the blade tip section 22. As Figure 2 and Figure 6 shown, the rotor blade 16 also defines a chord 25, and the chord 25 is equal to the total length between the leading edge 24 and the trailing edge 26 of the rotor blade 16. As generally understood, as the rotor blade 16 extends from the blade root section 20 to the blade tip section 22, the chord 25 can be substantially different in length relative to the span 23.

[0044] With particular reference to Figures 2 - 4 , any number of blade segments 21 of any suitable size and / or shape can be substantially arranged between the blade root section 20 and the blade tip section 22 along the longitudinal axis 27 in a direction generally along the span. Thus, the blade segments 21 generally serve as a housing / covering for the rotor blade 16 and can define a substantially aerodynamic profile including a pressure side surface 31 and a suction side surface 33( Figure 3 and Figure 4 ), such as by defining a cross-section of a symmetric or arcuate airfoil shape. In additional embodiments, it should be understood that the blade segment portion of the blade 16 can include any combination of the segments described herein and is not limited to the embodiments as depicted. Additionally, the blade segments 21 can be constructed of any suitable material, including but not limited to thermosetting or thermoplastic materials optionally reinforced with one or more fibrous materials. More particularly, in certain embodiments, the blade segments 21 can include a pressure side segment 44 and / or a suction side segment 46( Figure 2 and Figure 3 ) and / or a leading edge segment 40 and / or a trailing edge segment 42( Figures 2 - 6 ), or the like.

[0045] More particularly, as Figure 4 shown, the leading edge segment 40 can have a front pressure side surface 28 and a front suction side surface 30. Similarly, as Figure 5 shown, each of the trailing edge segments 42 can have a rear pressure side surface 32 and a rear suction side surface 34. Thus, the front pressure side surface 28 of the leading edge segment 40 and the rear pressure side surface 32 of the trailing edge segment 42 generally define the pressure side surface of the rotor blade 16. Similarly, the front suction side surface 30 of the leading edge segment 40 and the rear suction side surface 34 of the trailing edge segment 42 generally define the suction side surface of the rotor blade 16. Additionally, asFigure 6 As particularly shown, the leading edge segment 40 and the trailing edge segment 42 can be joined at the pressure side seam 36 and the suction side seam 38. For example, the blade segments 40, 42 can be configured to overlap at the pressure side seam 36 and / or the suction side seam 38. Additionally, as Figure 2 shown, the adjacent blade segments 21 can be configured to overlap at the seam 54. Thus, in the case where the blade segments 21 are at least partially made of a thermoplastic material, the adjacent blade segments 21 can be welded together along the seams 36, 38, 54, which will be discussed in more detail herein. Alternatively, in some embodiments, the various segments of the rotor blade 16 can be fixed together via an adhesive (or mechanical fastener) configured between the overlapping leading edge segment 40 and trailing edge segment 42 and / or the overlapping adjacent leading edge segment 40 or trailing edge segment 42.

[0046] In certain embodiments, as Figures 2 - 3 and Figures 6 - 7 shown, the blade root section 20 can include one or more longitudinally extending spar caps 48, 50 potted therewith. Similarly, the blade tip section 22 can include one or more longitudinally extending spar caps 51, 53 potted therewith. More particularly, as shown, the spar caps 48, 50, 51, 53 can be configured to engage against opposite inner surfaces of the blade segments 21 of the rotor blade 16. Additionally, the blade root spar caps 48, 50 can be configured to align with the blade tip spar caps 51, 53. Thus, the spar caps 48, 50, 51, 53 can generally be designed to control the bending stresses and / or other loads acting on the rotor blade 16 in a generally spanwise direction (a direction parallel to the span 23 of the rotor blade 16) during operation of the wind turbine 10. Additionally, the spar caps 48, 50, 51, 53 can be designed to withstand the spanwise compression that occurs during operation of the wind turbine 10. Further, the spar caps 48, 50, 51, 53 can be configured to extend from the blade root section 20 to the blade tip section 22 or a portion thereof. Thus, in some embodiments, the blade root section 20 and the blade tip section 22 can be joined together via their respective spar caps 48, 50, 51, 53.

[0047] Additionally, the spar caps 48, 50, 51, 53 can be made of any suitable material (such as a thermoplastic or thermosetting material or a combination thereof). Further, the spar caps 48, 50, 51, 53 can be pultruded from a thermoplastic or thermosetting resin. As used herein, the terms "pultrusion", "pultruded article" or the like generally encompass a reinforcing material (such as fibers or woven or braided strands) that is impregnated with a resin and pulled through a fixed die such that the resin cures or undergoes polymerization. Thus, the process of manufacturing a pultruded component is typically characterized as a continuous process of a composite material that results in a composite part having a constant cross-section. Accordingly, the pre-cured composite material can include a pultruded article made of a reinforced thermosetting or thermoplastic material. Additionally, the spar caps 48, 50, 51, 53 can be formed from the same pre-cured composite or different pre-cured composites. Further, the pultruded member can be produced from rovings, which generally comprise long and narrow bundles of fibers that are not combined until joined by a cured resin.

[0048] Referring Figures 6 - 7 , one or more shear webs 35 can be constructed between one or more of the spar caps 48, 50, 51, 53. More particularly, the shear web 35 can be configured to increase rigidity in the blade root section 20 and / or the blade tip section 22. Additionally, the shear web 35 can be configured to close out the blade root section 20.

[0049] Now referring Figures 8 - 14 , the present disclosure relates to a method for joining a first blade member and a second blade member of a rotor blade 16 (such as via 3-D printing) at a joint. For example, in one embodiment, the first blade member and the second blade member can include the pressure side surface 31 and / or the suction side surface 33 of the rotor blade 16, the shear web 35, the spar caps 48, 50, 51, 53, and / or combinations thereof. Accordingly, the methods of the present disclosure can be used in various joint areas or connections, including but not limited to spar cap / shear web connections, spar cap / blade shell connections, and / or blade shell / blade shell connections. More particularly, in certain embodiments, the blade shell / blade shell connection can include the trailing edge 26 and / or the leading edge 24 of the rotor blade 16. Thus, Figures 8 - 14 the illustrated embodiment shows a process of forming a first joint area 68 and a second joint area 72 between the pressure side surface 31 and / or the suction side surface 33 (i.e., at the trailing edge 26 and the leading edge 24).

[0050] As used herein, 3-D printing is generally understood to encompass processes for synthesizing three-dimensional objects, where successive layers of material are formed under computer control to produce the object. Thus, objects of almost any size and / or shape can be produced from digital model data. It should also be understood that the methods of the present disclosure are not limited to 3-D printing, but may also include more than three degrees of freedom, such that the printing techniques are not limited to printing stacked two-dimensional layers, but can also print curved shapes.

[0051] With particular reference to Figure 8 , one embodiment of the method includes positioning a mold 58 of a rotor blade 16 (or one of the blade segments 21) relative to a CNC device 60. More particularly, as shown in the illustrated embodiment, the method may include placing the mold 58 into the bed 64 of the CNC device 60. Alternatively, the method may include placing the mold 58 below or adjacent to the CNC device 60.

[0052] In addition, as shown, the methods of the present disclosure further include forming one or more fiber-reinforced outer skin surfaces 56 in a mold 58 of a rotor blade 16. In certain embodiments, the outer skin surface 56 (which forms the pressure side surface 31 and / or the suction side surface 33) may include one or more continuous multi-axial (e.g., biaxial) fiber-reinforced thermoplastic or thermoset outer skins. Additionally, in certain embodiments, the method of forming the fiber-reinforced outer skin surface 56 may include at least one of injection molding, 3-D printing, 2-D pultrusion, 3-D pultrusion, thermoforming, vacuum forming, pressure forming, bladder forming, automated fiber deposition, automated fiber tape deposition, or vacuum infusion.

[0053] For example, in one embodiment, a thermoset material may be infused into the fiber material on the mold 58 using vacuum infusion to form the outer skin surface 56. Thus, after curing, the vacuum bag is removed and then the grid structures 66, 70 described herein can be printed onto the inner surface of the outer skin surface 56. Alternatively, the vacuum bag may be left in place after curing. In such embodiments, the vacuum bag material may be selected such that the material will not readily release from the cured thermoset fiber material. For example, such materials may include thermoplastic materials such as polymethyl methacrylate (PMMA) or polycarbonate film. Thus, the thermoplastic film left in place allows the thermoplastic grid structure 66 to be bonded to the thermoset skin with the intervening film.

[0054] In still other embodiments, the outer skin surface 56 may be formed of a reinforced thermoplastic resin, where the grid structures 66, 70 are formed of a thermoset-based resin with optional fiber reinforcement. In such embodiments, depending on the thermoset chemistry involved—the grid structures 66, 70 may be printed onto the outer skin surface 56 when the surface 56 is still hot, warm, partially cooled, or fully cooled.

[0055] Additionally, the outer skin surface 56 may be treated to promote bonding between the outer skin surface 56 and the grid structures 66, 70. More particularly, in certain embodiments, flame treatment, plasma treatment, chemical treatment, chemical etching, mechanical abrasion, imprinting, raising the temperature of at least the area to be printed onto the outer skin surface 56, and / or any other suitable treatment method may be used to treat the outer skin surface 56 to promote the bonding. In additional embodiments, the method may include forming the outer skin surface 56 with more (or even less) matrix resin material on the inner surface to promote the bonding. In additional embodiments, the method may include varying the outer skin thickness and / or fiber content and fiber orientation.

[0056] Additionally, as shown, the outer skin surface 56 of the rotor blade 16 may be curved. In such embodiments, the method may include forming the curvature of the outer skin surface 56. Such forming may include providing one or more generally flat fiber-reinforced outer skin surfaces, forcing the outer skin surface 56 into a desired shape corresponding to a desired profile, and holding the outer skin surface 56 in the desired shape during printing and deposition. Thus, when the outer skin surface 56 and the grid structures 66, 70 printed thereon are released, the outer skin surface 56 generally retains its desired shape. Additionally, the CNC device 60 may be adapted to include a tooling path along the profile of the rotor blade 16.

[0057] Thus, as Figure 9 shown, one embodiment of the method includes directly printing and depositing the grid structure 66 onto the inner surface of the outer skin surface 56 via the CNC device 60. More particularly, as shown, the CNC device 60 is configured to print and deposit at least the first grid structure 66 onto the inner surface of the first outer surface at the first joint region 68 of the rotor blade 16. Additionally, as shown, the CNC device 60 may print and deposit the second grid structure 70 onto the inner surface of the first outer surface 56 at a different second joint region 72.

[0058] It should be understood that any suitably shaped grid structures 66, 70 described herein can be printed and deposited as desired. Thus, in some embodiments, when depositing grid structures 66, 70, grid structures 66, 70 can be incorporated into the outer skin 56, which respectively reduces the amount of adhesive and / or the curing time required for the first joint region 68 and the second joint region 72. For example, as Figure 13 and Figure 14 shown in, various embodiments showing different shapes and sizes of the grid structure 66 at the trailing edge 26 are shown. More particularly, as shown in the illustrated embodiments, the grid structure 66 can have a size in the range of about 10 millimeters (mm) to about 300 mm. However, it should be understood that the size of the grid structures 66, 70 can depend on the size and shape of the rotor blade 16. Additionally, as Figure 13 shown in, the grid structure 66 can extend from the adhesive 74 at the trailing edge 26 by up to, for example, 30% of the chord length. Alternatively, as Figure 14 shown in, the grid structure 66 can be spaced apart from the adhesive 74 at the trailing edge 26 in order to minimize the weight at the joint region 68.

[0059] For example, in one embodiment, the CNC device 60 is configured to print and deposit the grid structures 66, 70 after the formed skin surface 56 has reached a desired state that enables the grid structures 66, 70 to be incorporated into it, i.e., based on one or more parameters of temperature, time, and / or hardness. Thus, in some embodiments where the skin surface 56 and the grid structures 66, 70 are formed from a thermoplastic matrix, the CNC device 60 can immediately print the grid structures 66, 70 onto it because the forming temperature of the skin surface 56 and the desired printing temperature that enables thermoplastic welding / bonding can be the same.

[0060] More particularly, in a particular embodiment, before the skin surface 56 has cooled from the forming process (i.e., when the skin is still hot or warm), the CNC device 60 is configured to print and deposit the grid structures 66, 70 onto the inner surface of the outer skin surface 56. For example, in one embodiment, the CNC device 60 is configured to print and deposit the grid structures 66, 70 onto the inner surface of the outer skin surface 56 before the surface 56 has completely cooled. Additionally, in another embodiment, the CNC device 60 is configured to print and deposit the grid structures 66, 70 onto the inner surface of the outer skin surface 56 when the surface 56 is partially cooled. Thus, suitable materials for the grid structures 66, 70 and the outer skin surface 56 can be selected such that the grid structures 66, 70 are bonded to the outer skin surface 56 during deposition. Thus, the grid structures 66, 70 described herein can be printed using the same material or different materials.

[0061] It should be understood that the grid structures 66, 70 of the present disclosure may include different shapes and / or designs (e.g., materials, widths, heights, thicknesses, shapes, etc. or combinations thereof). Thus, the grid structures 66, 70 may define any suitable shape to form any suitable structure that can be used at any joint connection within the rotor blade 16, such that the adhesive in such joints can be reduced. Accordingly, the CNC device 60 can be designed to have one or more extruders 62 that generate any suitable thickness or width in order to disperse a desired amount of resin material to produce grid structures 66, 70 with different heights and / or thicknesses. For example, many rotor blade joints include tight angles and / or tapered sections that are conventionally filled with adhesive. Thus, as Figure 10 specifically shown, the grid structures 66, 70 of the present disclosure can be printed to contact the two inner surfaces of the pressure side surface 31 and / or the suction side surface 33. Thus, in such embodiments, the grid structures 66, 70 may include a tapered chordwise cross-section.

[0062] In yet another embodiment, the CNC device 60 can also print and deposit one or more alignment structures 82 into the grid structures 66, 70. For example, as Figure 11 and Figure 12 shown, the grid structures 66, 70 may include alignment structures 82 that are printed along with the grid structures 66, 70 to assist in aligning adjacent rotor blade components (such as printed reinforcement grids for the pressure side surface 31 and / or the suction side surface 33).

[0063] When printing the grid structures 66, 70 using extruded thermoplastics with a more compact gap, the structures 66, 70 can retain heat as the printed structure becomes taller. Additional heat can also be retained when the shape of many rotor blade joints is tapered or angled (thus requiring grid structures 66, 70 within the tapered or angled cross-sections). Consequently, during part construction, the print layer time becomes shorter. As a result, because there is not enough cooling time to fully solidify the previous layer, taller structures and those 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. Thus, the method of the present disclosure is configured to slow down the printing speed as needed, change the formulation of the resin system to use a more rapidly solidifying resin matrix (e.g., a more semi-crystalline / less amorphous formulation), and / or selectively apply cooling air to the grid structures 66, 70 during printing and deposition. For example, in one embodiment, as Figure 9 shown, the CNC device 60 can include one or more cooling fans 82 or cooling air nozzles that are selectively turned on as needed to cool the grid structures 66, 70.

[0064] In addition to additive manufacturing, the lattice structures 66, 70 of the present disclosure may also be formed at least in part from one or more prefabricated sections of honeycomb material. For example, in one embodiment, the honeycomb preform material may be CNC machined to conform to the desired shape required at the joints, and an adhesive may be applied to both inner surfaces of the outer skin surface 56 to bond the honeycomb material in place. In another embodiment, the thermoplastic honeycomb material may be press formed under pressure and / or heated together with an adhesive.

[0065] As Figures 10 - 14 shown, after the lattice structures 66, 70 are printed on the outer skin surface 56, the method may include providing an adhesive 74 at the first joint region 68 and / or the second joint region 72, for example, at least partially filling the lattice structures 66, 70. Thus, the method further includes placing the second outer surface on top of the first outer surface and the printed lattice structures 66, 70, and securing the first outer skin surface 31 and the second outer skin surface 33 together at the first joint 73 and the second joint 75 via the adhesive 74. Thus, as Figure 10 shown, the first joint 73 includes the trailing edge 26 of the rotor blade 16, where the pressure side surface 31 and the suction side surface 33 of the rotor blade 16 are secured together. Similarly, as shown, the second joint 75 includes the leading edge 24 of the rotor blade 16, also where the pressure side surface 31 and the suction side surface 33 of the rotor blade 16 are secured together.

[0066] In such embodiments, as Figure 11 , Figure 13 and Figure 14 shown, the first lattice structure 66 may be spaced from the trailing edge 26 of the rotor blade 16 to provide a first gap 76. More particularly, as Figure 13 and Figure 14 shown, for example, the first gap 76 may extend from about 1% to about 20% of the chord length of the rotor blade 16. It should be understood that the first gap 76 may include any suitable chord length sufficient to bond the pressure side surface 31 and the suction side surface 33. Additionally, as Figure 12 shown, the second lattice structure 70 may also be spaced from the leading edge 24 of the rotor blade 16 to provide a second gap 78. Similarly, for example, the second gap 78 may extend from about 1% to about 20% of the chord length of the rotor blade 16. Furthermore, it should be understood that the second gap 78 may include any suitable chord length sufficient to bond the pressure side surface 31 and the suction side surface 33.

[0067] Thus, the method may further include at least partially filling the first gap 76 and / or the second gap 78 with the adhesive 74. For example, as Figure 10 and Figure 11As shown, the first gap 76 can be completely filled with the adhesive 74. Alternatively, as Figure 13 shown, only a portion of the first gap 76 can be filled with the adhesive 74. Additionally, as Figure 10 and Figure 12 shown, the second gap 78 can be made substantially free of the adhesive 74. Alternatively, the second gap 78 can be partially or completely filled with the adhesive 74.

[0068] In another embodiment, the method can include forming at least a portion of the grid structure 62 of the foaming agent 80. For example, as Figure 11 shown, a portion of the grid structure 66 at the first joint region 68 is formed of the foaming agent 80 to further reduce the weight of the structure 62 and thus the overall rotor blade 16.

[0069] The methods of the present disclosure can also be useful for certain types of blade attachment members where certain aerodynamic features are desired to be added to the outer surface of the rotor blade after production and / or added to an existing rotor blade in the field. Thus, now referring to Figure 15 , a flowchart of one embodiment of a method 100 for attaching a blade attachment member to a rotor blade 16 is shown. As shown at 102, the method 100 includes printing and depositing at least one three-dimensional (3-D) grid structure via the CNC device 60 to form the blade attachment member. As shown at 104, the method 100 includes placing the blade attachment member onto or within the rotor blade. As shown at 106, the method 100 includes providing an adhesive to at least partially fill the grid structure. As shown at 108, the method 100 includes attaching the blade attachment member to the rotor blade via the adhesive.

[0070] Examples of blade attachment members can include a flat-back airfoil corner section, a tip extension (i.e., a grid structure used to fill the thin section between the interface (sock) tip and the rotor blade 16 and allowing the use of this grid technology for bonding), or a reinforcement structure for the leading or trailing edge.

[0071] This written description uses examples to disclose the invention (including the best mode), and enables any person skilled in the art to practice the invention, including making and using any device or system and performing any combined methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. If such other examples include structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims, such other examples are intended to be within the scope of the claims.

Claims

1. A method for joining a first blade member and a second blade member of a rotor blade, the first blade member and the second blade member at least including a first outer surface and a second outer surface of the rotor blade, the method comprises: printing and depositing a three-dimensional first grid structure via a computer numerical control device at a first joint region of the rotor blade onto an inner surface of the first outer surface and spaced apart from a trailing edge of the rotor blade to provide a first gap, the first joint region including the first blade member that docks with the second blade member; providing an adhesive at the first joint region such that the adhesive contacts at least a portion of the first grid structure to bond the first grid structure to the second outer surface and at least partially fill the first gap, wherein the first joint region at least includes a blade shell / blade shell connection; printing and depositing a second grid structure via the computer numerical control device at a different second joint region of the rotor blade onto the inner surface of the first outer surface and spaced apart from a leading edge of the rotor blade to provide a second gap; providing an adhesive at the second joint region such that the adhesive contacts at least a portion of the second grid structure to bond the second grid structure to the second outer surface and at least partially fill the second gap, and fixing the first blade member and the second blade member together at the first joint region and the second joint region via the adhesive.

2. The method according to claim 1, wherein, the adhesive at least partially fills the first grid structure.

3. The method according to claim 1, wherein, the method further comprises: placing the first outer surface into a mold of the rotor blade; when depositing the first grid structure, the first grid structure bonds to the first outer surface; placing the second outer surface on top of the first outer surface; and fixing the first outer surface and the second outer surface together via the adhesive.

4. The method according to claim 1, wherein, the method further comprises forming at least a portion of at least one of the first grid structure and the second grid structure as a foaming agent.

5. The method according to claim 1, wherein, the method further comprises selectively applying cooling air to at least one of the first grid structure and the second grid structure during printing and deposition.

6. The method according to claim 1, wherein, the method further comprises printing and depositing one or more alignment structures via the computer numerical control device into at least one of the first grid structure and the second grid structure.

7. The method according to claim 1, wherein, at least one of the first grid structure and the second grid structure includes a tapered chordwise cross-section that contacts an inner surface of the first outer surface and an inner surface of the second outer surface.

8. A joint region of a rotor blade of a wind turbine, the joint region comprises: First blade member; Second blade member, the second blade member butting against the first blade member at the joint; At least one three-dimensional grid structure, the at least one three-dimensional grid structure being positioned between the first blade member and the second blade member adjacent to the joint and spaced apart from the leading edge or the trailing edge of the rotor blade to provide a gap between the at least one three-dimensional grid structure and the leading edge or the trailing edge; And Adhesive, the adhesive being provided between the at least one three-dimensional grid structure and the first blade member and the second blade member and at least partially filling the gap, wherein the joint at least includes a blade shell / blade shell connection.

9. The joint region according to claim 8, characterized in that the adhesive at least partially fills the at least one three-dimensional grid structure.

10. The joint region according to claim 8, characterized in that the first blade member and the second blade member further include at least one of a spar cap, a shear web, or the first outer surface and the second outer surface of the rotor blade.

11. The joint region according to claim 8, characterized in that the at least one three-dimensional grid structure is at least partially formed by additive manufacturing.

12. The joint region according to claim 8, characterized in that the at least one three-dimensional grid structure is at least partially formed of prefabricated honeycomb material.

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