Coating applicator tool with a curved applicator nozzle

Abstract

An applicator tool (42) for repairing damage (26) to a leading edge (22) of a wind turbine blade (20) is disclosed The applicator tool (42) includes a tool frame (70) and an outer spatula (76) operatively supported by the tool frame (70). The outer spatula (76) is configured to engage with an exterior surface (34) of the wind turbine blade (20) to form a gap (86) between the leading edge (22) of the wind turbine blade (20) and the outer spatula (76). A feed tube (94) of the applicator tool (42) is supported by the tool frame (70) to supply a coating material to the gap (86) and an applicator nozzle (88) of the applicator tool (42) that is located within the gap (86). The applicator nozzle (88) is operatively connected to the feed tube (94) and includes an applicator head (156) that is configured to distribute the coating material onto the wind turbine blade (20). The applicator head (156) includes at least three passageways (176-180) that define at least three distinct flows of coating material from the applicator nozzle (88). The applicator head (156) is curved along a transverse axis (A3) that is perpendicular to a longitudinal axis (A2) of the applicator nozzle (88) to generally conform the applicator head (156) to a curved contour of the leading edge (22) of the wind turbine blade (20). (Figure 5)

Description

[0001]COATING APPLICATOR TOOL WITH A CURVED APPLICATOR NOZZLE Technical Field This application relates generally to wind turbines, and more particularly to an applicator tool for use with a robotic device for repairing damage along the leading edge of a wind turbine blade without necessitating removal of the blade from the tower of the wind turbine or manual repairs by rope access technicians. Background Wind turbines are used to produce electrical energy using a renewable resource and without combusting a fossil fuel. Generally, a wind turbine converts kinetic energy from the wind into electrical power. A conventional wind turbine installation includes a foundation, a tower supported by the foundation, and an energy generating unit positioned atop of the tower. The energy generating unit typically includes one or more nacelles to house several mechanical and electrical components, such as a generator, gearbox, and main bearing, and the wind turbine also includes a rotor operatively coupled to the components in the nacelle through a main shaft extending from the nacelle. Single rotor wind turbines and multi-rotor wind turbines (which may have multiple nacelles) are known, but for the sake of efficiency, the following description refers primarily to single rotor designs. The rotor, in turn, includes a central hub and a plurality of blades extending radially therefrom and configured to interact with the wind to cause rotation of the rotor. The rotor is supported on the main shaft, which is either directly or indirectly operatively coupled with the generator which is housed inside the nacelle. Consequently, as wind forces the blades to rotate, electrical energy is produced by the generator. Wind power has seen significant growth over the last few decades, with many wind turbine installations being located both on land and offshore. As noted above, blades interact with the wind to generate mechanical rotation of the rotor, which can then be converted into electrical energy. A wind turbine blade is a complex structure that must be constructed to withstand long-term service in an abusive environment, while also maximizing lift and minimizing drag forces. The blades move at varying speeds through the ambient environment surrounding the wind turbine, but often this movement is at high speed. Consequently, the blades will typically experience erosion and damage over time in operation as a result of friction 1   from the air as well as potential impacts from rain, particulate matter, debris, or other items in the air, especially along the leading edge that is configured to face the direction of movement through the wind. The erosion or damage along the leading edge of the blade adversely affects the aerodynamic qualities of the blade over time, resulting in lower power production for given incoming wind speeds. Such erosion and damage on the blades can be corrected by routine maintenance and repair procedures. The blades are typically formed from a shell of layered fiber composite, aluminum, or similar material with an outer skin defined by a series of layers of coatings (polymeric elastomers, paint, etc.) surrounding and covering an outer surface of the shell. The shell encloses internal components of the blade and isolates them from the environment, including shear webs and spar caps, for example. The outer skin may be defined by several different layers of material, including at least an outermost topcoat, a second layer underneath the outermost topcoat, and a third layer underneath the second layer. Other layers are typically present underneath the third layer as well, including base materials typically made from fiber composites and the like. Damage to the blade outer skin can be categorized into several different levels of severity based on which layer the damage extends to, e.g., an erosion to the third layer would be a "category 2" level of severity, which would be higher than a cut to the second layer, which would be a "category 1" level of severity. For low levels of damage or erosion, such damage can be repaired by depositing a coating onto the area to fill in the damage and restore the blade to the original condition along the leading edge thereof. Conventionally, repairs of the wind turbine blades have been conducted in three ways. First, the blade can be disassembled from the remainder of the wind turbine and lowered to the ground for the repair to be completed. Such a repair process is time- consuming and costly as a result of needing to disassemble, move, and reassemble the blade relative to the top of the tower. Second, a human operator with rope access can rappel along the wind turbine blade while still attached to the rotor hub to evaluate and make repairs as needed to the blade. Once again, such a repair process is time- consuming and costly because of the need for experienced rope access technicians and the time needed to effect the repairs manually. Third, a repair action can be taken 2   by an operator on a platform hoisted into position adjacent the blade on the wind turbine, either extending from the nacelle or hub of the wind turbine or extending from a cherry picker or boom-style lift. In all conventional methods, the wind turbine must be stopped and locked for the time period of repair, and as such, significant power production losses are experienced by wind turbine operators for these necessary maintenance and repair actions. This may lead some operators to delay or procrastinate in making such repairs, which can lead to more significant structural damage and even longer delays when more thorough repairs are necessary on the wind turbine blade. In recent years, a desire has emerged to allow for some automated or semi- autonomous maintenance of wind turbine blades, to thereby improve the speed and / or precision of such a process. However, such maintenance devices are not always designed for reliable use on a wind turbine blade still connected to the rotor and hub of a wind turbine, and such systems are very slow in operation. Furthermore, such systems may be prone to uneven or misshapen coatings that may not be precisely positioned to assure that the repair remains fully effective and bonded over a long period of time to the previous exterior surface of the blade. Thus, further improvements for maintenance and repair systems are desired. Summary To these and other ends, an applicator tool for repairing damage to a leading edge of a wind turbine blade is disclosed. The applicator tool includes a tool frame and an outer spatula operatively supported by the tool frame. The outer spatula is configured to engage with an exterior surface of the wind turbine blade to form a gap between the leading edge of the wind turbine blade and the outer spatula. A feed tube of the applicator tool is supported by the tool frame to supply a coating material to the gap and an applicator nozzle of the applicator tool is located within the gap. The applicator nozzle is operatively connected to the feed tube and includes an applicator head that is configured to distribute the coating material onto the wind turbine blade. The applicator head includes at least three passageways that define at least three distinct flows of coating material from the applicator nozzle. The applicator head is curved along a transverse axis that is perpendicular to a 3   longitudinal axis of the applicator nozzle to generally conform the applicator head to a curved contour of the leading edge of the wind turbine blade. A robotic maintenance device may include the applicator tool in accordance with an embodiment of the invention. According to one embodiment of the invention, the applicator tool may include an inner spatula located between the outer spatula and the applicator nozzle / The inner spatula may be configured to shape the coating material dispensed from the applicator nozzle into a coating over the leading edge of the wind turbine blade. In one embodiment, the inner spatula may include a front edge, a rear edge, opposed side edges, an outer surface, and an inner surface. The inner surface may be configured to engage the applicator nozzle and the wind turbine blade. In another embodiment, the inner spatula may include one or more ribs positioned on the inner surface adjacent the front edge of the inner spatula. The one or more ribs may be configured to define a gap between the exterior surface of the wind turbine blade and the inner surface of the inner spatula. In one embodiment, the one or more ribs may be elongate and extend a length from a first end located adjacent to the front edge of the inner spatula to a second end in a direction toward the rear edge of the inner spatula. In yet another embodiment, the one or more ribs may include a chamfered surface that extends from the first end along a portion of the length of the one or more ribs to vary a height that the one or more ribs extend from the inner spatula. According to one embodiment, the one or more ribs may be integrally formed with the inner spatula. According to one embodiment of the invention, the applicator head of the applicator nozzle may be positioned along the inner surface of the inner spatula and adjacent the one or more ribs. For example, the applicator head of the applicator nozzle may be configured to be compressed between the tool frame and the leading edge of the wind turbine blade to vary a flowrate of the at least three flows of coating material from the applicator nozzle. In another embodiment, the at least three passageways of the applicator head of the applicator nozzle may each include an inlet opening and an outlet opening, and a 4   maximum width of each outlet opening may be greater than a maximum width of each inlet opening. In yet another embodiment, the at least three passageways of the applicator head may include a central passageway, a first outboard passageway, and a second outboard passageway. The first outboard passageway and the second outboard passageway may be configured to be located on opposing sides of the leading edge of the wind turbine blade. Furthermore, a volume flow rate of coating material through the central passageway may be greater than a volume flowrate of material through the first outboard passageway and the second outboard passageway. According to one embodiment, the first outboard passageway and the second outboard passageway may be angled relative to the longitudinal axis of the applicator nozzle. According to one embodiment, the applicator tool may include a first chamfer arm and a second chamfer arm operatively coupled to the tool frame. Each chamfer arm may be configured to engage the outer surface of the outer spatula to press the outer spatula towards the exterior surface of the wind turbine blade on opposing sides of the leading edge of the wind turbine blade. In another embodiment, the applicator tool may include an end effector removably attached to each of the first chamfer arm and the second chamfer. The end effector may include a pad configured to engage the outer spatula. In yet another embodiment, the applicator nozzle may be symmetrical about a central axis of the applicator nozzle. Additionally or alternatively, the inner spatula may be symmetrical about a central axis of the inner spatula. In one embodiment, the applicator nozzle and / or the inner spatula may be a single-use part to be disposed of after a blade repair operation. According to another aspect of the invention, a method of repairing damage to a leading edge of a wind turbine blade is disclosed. The method includes providing the applicator tool according to any one of the embodiments described above. The method further includes engaging the applicator tool to the exterior surface of the wind turbine blade, supplying the coating material to the applicator tool, moving the applicator tool along the leading edge of the wind turbine blade, and dispensing the coating material from the applicator tool to form the coating over a damaged area of the wind turbine 5   blade. According to one embodiment, the method may further include providing a robotic maintenance device including the applicator tool. According to another embodiment of the invention, the method may include operating the first chamfer arm and the second chamfer of the applicator tool to shape the coating material dispensed from the applicator nozzle into a coating over the leading edge of the wind turbine blade. In yet another embodiment, the method may include disposing of the applicator nozzle and / or the inner spatula after the damaged area of the wind turbine blade has been repaired. The elements and steps described herein can be reconfigured and combined in many different combinations to achieve the desired technical effects for different styles of wind turbines and different repair systems, as may be needed in the art. Brief Description of the Drawings The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention. Fig. 1 is a perspective view of a wind turbine according to one embodiment of the invention. Fig. 2 is a front view of a wind turbine blade of the wind turbine of Fig. 1, showing various levels of erosion-type damage along a leading edge that is pitched upwardly. Fig.3 is an enlarged cross-sectional view of the wind turbine blade shown in Fig.2 with a coating applied over the damaged region on the leading edge of the blade. Fig.4 is a top perspective view of a robotic maintenance device including a coating applicator tool head in accordance with embodiments of the present invention, the maintenance device being arranged in position on the leading edge of the wind turbine blade of Figs.1 through 3. 6   Fig.5 is a side view of an applicator tool being used to repair damage to the leading edge of the wind turbine blade in accordance with embodiments of the present invention. Fig.6 is a front view of the applicator tool of Fig.5, illustrating an actuated position of a first chamfer arm and a second chamfer arm in accordance with embodiments of the present invention. Fig. 7 is a perspective view of a nozzle in engagement with an inner spatula of the applicator tool in accordance with embodiments of the present invention. Fig.8 is a perspective view of the nozzle, schematically illustrating the passageways through which coating material may flow through the nozzle. Fig. 9 is a perspective view of the inner spatula of the applicator tool, illustrating additional details of one or more ribs positioned on an inner surface of the inner spatula. Fig.10 is an enlarged perspective view of the one or more ribs of the inner spatula of the applicator tool. Detailed Description With reference to Figs. 1 through 10, embodiments of a coating applicator tool configured to be used with a robotic (automated or semi-autonomous) maintenance device and a method for repairing damage around a leading edge of a wind turbine blade are shown in detail. The applicator tool for repairing so-called category-1 and category-2 damage to the outer skin of a wind turbine blade includes an outer spatula, an inner spatula, an applicator nozzle, and one or more chamfer arms for properly shaping the coating material dispensed from the applicator nozzle onto the leading edge of the wind turbine blade as the applicator tool is moved along the blade. In one embodiment, the applicator nozzle is configured to be self-centering over the leading edge of the wind turbine blade so that coating material dispensed from the applicator nozzle may be uniformly shaped onto the leading edge by the inner and 7   outer spatulas. The self-centering configuration of the applicator nozzle ensures that coating material is applied to wind turbine blade such that the coating is symmetrical (i.e., uniform and even about the leading edge). Moreover, the applicator nozzle may be resilient, allowing it to be pinched or compressed between parts of the applicator tool and the leading edge to generally deform the applicator nozzle. Being that the applicator nozzle is resilient, the applicator nozzle is configured to return to its original shape when no longer compressed between parts of the applicator tool and the leading edge. The applicator nozzle being resilient means that it will exert some force onto the leading edge when being compressed causing a better sealing against the blade surface. The ability to temporarily deform the applicator nozzle allows for modulating the flow rate of coating material through the applicator nozzle and modifying the shape or profile of the dispensed coating. The inner and outer spatulas are configured to shape coating material into a uniform and even coating that, in cross section, is generally thickest adjacent the leading edge of the blade and decreases in thickness in a generally continuous and smooth manner along the upper and lower surfaces of the blade and in a direction toward a trailing edge of the blade. In one embodiment, the chamfer arms of the applicator tool may include end effector attachments to facilitate shaping of the coating material onto the wind turbine blade. The applicator nozzle, inner spatula, and end effector attachments may be disposable (e.g., single or limited use) wear parts, for example. These and other benefits of the present invention will be described in further detail below. Throughout this application, the correction of erosion damage on wind turbine blades is typically referred to as a “repair” of those damages. In some contexts, “damage” refers to more significant damages to the blade (perhaps beyond what is described as “category-1” and “category-2” damage herein), and so the operation of the applicator tool may be deemed a routine maintenance action that occurs before a blade is “damaged” in such contexts. In this regard, it will be understood that within the context of this application, the applicator tool is capable of providing preventative maintenance to remove wear and erosion effects before such effects cause “damage” that must be repaired on the wind turbine blade, and the applicator tool is also capable of providing more thorough repairs after damage is caused on the blade. 8   Referring now to Fig.1, a wind turbine 10 is shown and includes a tower 12, a nacelle 14 disposed at the apex of the tower 12, and a rotor 16 operatively coupled to a generator (not shown) housed inside the nacelle 14. The rotor 16 of the wind turbine 10 includes a central hub 18 and a plurality of wind turbine blades 20 that project outwardly from the central hub 18 at locations circumferentially distributed around the hub 18. As shown, the rotor 16 includes three wind turbine blades 20, but the number of blades 20 may vary from one wind turbine to another. The wind turbine blades 20 are configured to interact with air flow to produce lift that causes the rotor 16 to spin generally within a plane defined by the wind turbine blades 20. As the rotor 16 spins, the wind turbine blades 20 pass through the air with a leading edge 22 leading the respective wind turbine blade 20 during rotation. As shown, each wind turbine blade includes a trailing edge 24 opposite the leading edge 22. The wind turbine blades 20 in use are spaced apart from the ground surface by a significant distance, which normally renders maintenance and repair actions difficult. However, the coating applicator tool in accordance with embodiments disclosed herein improves the repair process to make automated or semi-automated repairs, particularly with the use of a robotic maintenance device, more efficient and less time-consuming as will be set forth in detail below. As the wind turbine 10 ages, one or more of the wind turbine blades 20 may experience erosion from prolonged, continuous exposure to the environment. One example of such erosion damage 26 is shown in Fig.1 and better shown in the detailed view of Fig.2. While not being particularly limited to any source, erosion damage 26 may occur due to particulates in the air that abrade the leading edge 22 of the wind turbine blade 20 during operation. Erosion therefore may occur in an erosion zone that includes the leading edge 22, but it may also occur in other areas in the surface of the blade 20. Accordingly, while the robotic maintenance device is configured to repair damage with the applicator tool and move along the leading edge 22 of the blade 20, this device may also be capable of conducting maintenance and repair actions elsewhere along the outer surface of the blades 20. Erosion damage 26 is generally characterized as a loss of material from the wind turbine blade 20. Material loss may be uniformly distributed but is often non-uniform across the leading edge 22 or any other surface of the wind turbine blade 20. Rather 9   than losing a uniform skin of material from a surface, erosion may include localized surface imperfections, such as random pitting and shallow gouges or crack-like features that may be a result of localized, connected pitting (as a result of impacts with debris or other matter in the environment). In any case, if erosion damage 26 is not repaired in a timely fashion, the wind turbine blade 20 may become less efficient at rotating the rotor 16 and, ultimately, the structural integrity of the wind turbine blade 20 may be significantly impaired. With reference to the detailed view of in Fig.2, it will be understood that the erosion damage 26 may define differing levels of severity based on how deep the damage 26 extends inwardly into the material layers defining the outer shell of the blade 20. In the example shown, the erosion damage 26 includes some areas with an erosion or cut of material through the outer topcoat layer into a second layer of material underneath the topcoat, which is categorized as a “category 1” level of severity, and further areas with an erosion or cut of material through the outer topcoat layer and the second later of material into a third layer of material underneath the second layer, which is categorized as a “category 2” level of severity. For reference, deeper cuts and erosions defining more significant damage is typically categorized at higher levels such as category 3, 4, or 5. In Fig.2, the topcoat is shown at 28a, the revealed areas of second layer are shown at 28b, and the revealed areas of third layer are shown at 28c. By identifying and correcting such lower levels of erosion damage 26 promptly by maintenance-style “repair actions,” more significant damage of the blade 20 can be avoided along with higher operational downtime caused by the more significant damage. Fig.3 illustrates a repaired section of a wind turbine blade 20 having damage 26 on the leading edge 22 of the blade 20. The repaired section includes a coating 30 of material over the damage 26 on the leading edge 22 of the blade 20. The coating 30 is configured to define a new outer surface 32 that interacts with the air flowing over the blade 20. As such, the coating 30 protects the damage 26 on the wind turbine blade 20 and prevents or reduces the likelihood of the damage 26 further advancing, such as to a higher category of damage. In addition, the coating 30 is preferably shaped so as to minimize any negative impacts of the repair on the aerodynamic 10   performance on the wind turbine blade 20 during use. Thus, the new outer surface 32 is configured to minimize disruptions of the air flow over the blade 20. With continued reference to Fig.3, the coating 30 is generally symmetrical about the leading edge 22 where the coating 30 is at a maximum thickness. The coating 30 decreases in thickness in a direction away from the leading edge 22 and toward the trailing edge (not shown) of the blade 20 along both of the outer surfaces 34 (i.e., leeward and windward sides) of the blade 20. Ideally, the thickness of the coating 30 should decay to substantially zero at the outer edges 36 of the coating 30. This allows the coating 30 to merge into the existing surfaces 34 of the blade 20 in a smooth manner, thereby minimizing the disruption of the air flow in the transition from the outer surface 32 of the coating 30 to the original outer surfaces 34 of the blade 20. In an exemplary embodiment, the coating 30 may be formed from an epoxy or a polyurethane, but other materials may also be possible. The applicator tool in accordance with embodiments of the invention aid in providing a precise and high- quality coating 30 on the leading edge 22 of the wind turbine blade 20 having the shape and features as described above. Fig. 4 illustrates an exemplary robotic maintenance device 40 equipped with an applicator tool 42 in accordance with one embodiment of the present invention. The robotic maintenance device 40 includes a main body 44 (also referred to as a main chassis) that extends between a first end 46 and a second end 48. As shown, the robotic maintenance device 40 is configured to align with and extend along the leading edge 22 of the blade 20 when mounted on the blade 20. The first end 46 of the robotic maintenance device 40 includes a tool head 50 configured to support the applicator tool 42 over the leading edge 22 of the blade 20. The applicator tool 42 is operatively coupled (e.g., mechanically and electrically) with the robotic maintenance device 40 via the tool head 50. The tool head 50 and main body 44 of the robotic maintenance device 40 may house components required to mechanically and electrically operate the applicator tool 42 and associated components. It will be appreciated that the wind turbine 10 is halted with the blade 20 to be worked upon in a generally horizontal orientation with the blade 20 pitched so that the leading edge 22 faces upwardly such that the robotic maintenance device 40 can then be placed upon the blade 20 as shown in Fig.4. 11   The robotic maintenance device 40 also includes a control system 52 shown schematically in Fig.4 and implemented on known hardware and software platforms. The control system 52 is operatively connected to the components of the robotic maintenance device 40, including the applicator tool 42 and associated components, and at least a movement drive (not shown in detail) for the maintenance device 40, to thereby operate these elements. More particularly, the control system 52 is capable of responding to inputs from components of the robotic maintenance device 40 and applicator tool 42 and / or from an offsite operator to modify or initiate the actions taken by the maintenance device 40. More particularly, the actions of the robotic maintenance device 40 and applicator tool 42 may be modified based on real-time feedback or inputs detected by the maintenance device 40 during repair operations. To stabilize the robotic maintenance device 40 as it moves along the leading edge 22 during repair operations, the robotic maintenance device 40 also includes two or more wheels 56 connected to the main body 44 of the maintenance device 40, as shown in Fig. 4. The wheels 56 are connected to an underside of the main body 44 via respective support arms 58 and steady movement of the robotic maintenance device 40 as it moves along the wind turbine blade 20. Additionally, a power supply 60 such as a battery pack may be mounted on the robotic maintenance device 40 for supplying power to components of the robotic maintenance device 40 such as the controller 52, the drive system, and the applicator tool 42, for example. The power supply 60 may be configured to power those components and systems so that the robotic maintenance device 40 can repair an entire leading edge 22 of a wind turbine blade 20, for example. The power supply 60 is shown schematically in Fig.4. The power supply 60 may also be used to provide operating power to additional elements or modules that may be connected to the robotic maintenance device 40 as well. Further examples of robotic maintenance devices are, for example, disclosed in DK Application Nos. PA 201970789 and PA 201970790, which are owned by the same Assignee as the present invention, and such robotic maintenance devices may be used in other embodiments with the applicator tool of the present invention. Further details of any exemplary robotic maintenance device can be understood from those prior patent applications in combination with the description provided herein. 12   Figs. 5-9 illustrate an applicator tool 42 in accordance with one embodiment of the invention. In accordance with this embodiment, the applicator tool 42 includes a frame 70 having a front support 72 and a rear support 74. The applicator tool 42 also includes an outer spatula 76 and an inner spatula 78 for shaping the coating 30 applied to the leading edge 22 of the wind turbine blade 20. The front support 72 of the frame 70 includes a first chamfer arm 80 and a second chamfer arm 82 operatively coupled thereto and configured to engage the outer spatula 76 at specific engagement locations on opposing sides of the wind turbine blade 20 to shape the coating material 30 via the inner spatula 78. As shown in Fig.5, the applicator tool 42 includes a feed nozzle 84 supported under the rear support 74. The feed nozzle 84 is configured to be located within a gap 86 between the leading edge 22 of the wind turbine blade 20 and the outer spatula 76 and the inner spatula 78. The feed nozzle 84 is configured to receive an applicator nozzle 88 that is configured to distribute the coating 30 onto the wind turbine blade 20, as will be described in further detail below. The feed nozzle 84 may be attached to the rear support 74 with one or more bracket(s) 90 and fastener(s) 92, as shown in Fig.5. The same bracket(s) 90 and fastener(s) 92 may also be used to secure the inner spatula 78 to the frame 70 of the applicator tool 42 as well. The feed nozzle 84 is operatively coupled with a feed tube or pipe 94 to a source of coating material 96, such as multi-cartridge supply, that is configured to supply the coating material 30 onto the leading edge 22 of the wind turbine blade 20 during repair operations. The source of coating material 96 may be a material supply container located on the robotic maintenance device 40, for example. The feed nozzle 84 extends from the feed tube 94 to a nozzle outlet 98 to which the applicator nozzle 88 is configured to attach. In one embodiment, the feed nozzle 84 may be configured as a permanent or non-wear part, while the applicator nozzle 88 may be configured as a wear part intended for replacement between uses. For instance, the applicator nozzle 88 may be removed and discarded after repairing the damaged area 26 of the wind turbine blade 20. A new applicator nozzle 88 may then be attached to the feed nozzle 84 for subsequent repair operations. With reference to Figs.5 and 6, the outer spatula 76 extends generally between the front support 72 and rear support 74 of the frame 70 of the applicator tool 42. The 13   outer spatula 76 is supported below the frame 70 by a pair of support arms 100 that terminate at respective brackets 102. Each bracket 102 is equipped with a clamp 104 designed to secure a corresponding edge 106 and a portion of the outer spatula 76 within a slot in the bracket 102 to thereby hold the outer spatula 76 between the pair of support arms 100. The support arms 100 are configured to press and hold the outer spatula 76 and the inner spatula 76 against the outer surfaces 34 of the wind turbine blade 20. More particularly, the outer spatula 76 and the inner spatula 78 are held against the wind turbine blade 20 so as to be centered over the leading edge 22 of the blade 20. That is, a central axis A1 of the inner spatula 78 and outer spatula 76 is aligned with the leading edge 22 of the blade 20, as shown in Fig.5. In an exemplary embodiment, the outer spatula 76 is generally flexible and / or resilient and made from, for example, rubber or other generally flexible and / or resilient engineering plastics. The outer spatula 76 may be generally rectangular in shape and include a front edge 108, a rear edge 110 facing the robotic maintenance device 40, and opposed side edges 106 that extend between the front and rear edges 108, 110. The outer spatula 76 may further include an outer surface 112 and an inner surface 114. The outer surface 112 is configured to face away from the leading edge 22 of the wind turbine blade 20 during use and the inner surface 114 is configured to face toward the leading edge 22 of the blade 20 during use. To that end, the inner surface 114 is configured receive and engage the inner spatula 78. As best shown in Figs.7 and 9 , the inner spatula 78 comprises a generally flexible and / or resilient body made from, for example, rubber or other generally flexible and / or resilient engineering plastics. The inner spatula 78 includes a front edge 116, a rear edge 118 facing the robotic maintenance device 40, and opposed side edges 120 that extend between the front and rear edges 116, 118. The inner spatula 78 may further include an outer surface 122 and an inner surface 124. The outer surface 122 is configured to engage the inner surface 114 of the outer spatula 76 during use. The inner surface 124 is configured to face toward and engage the leading edge 22 of the blade 20 during use. To engage the outer spatula 76 and the inner spatula 76 with the surfaces 34 of the blade 20, each support arm 100 includes a piston 126 and an actuator 128 configured 14   to drive the piston 126 up and down. As shown in Fig. 6, each piston 126 extends between the corresponding actuator 128 and bracket 102 to position the bracket 102 and corresponding side edge 106 of the outer spatula 76 downward along the respective sides of the wind turbine blade 20. The support arms 100 are hingeably coupled to the front support 72 of the frame 70 via linkages to pivot about respective joints 130. In that regard, as the pistons 126 are driven downward or raised by the actuators 128, each support arm 100 is permitted to freely pivot about the frame 70 at the corresponding joint 130. The robotic maintenance device 40 is configured to support the applicator tool 42, and more particularly position the inner spatula 78 and the outer spatula 76 over the leading edge 22 of the blade 20 during repair operations. Specifically, the applicator tool 42 is supported over the leading edge 22 such that the front support 72 of the frame 70 is positioned closer to the leading edge 22 compared to the rear support 74, resulting in the applicator tool 42 being generally angled relative to the leading edge 22 during the repair operations. As shown in Fig.5, the rear edge 118, 110 of the inner spatula 78 and the outer spatula 76, respectively, is above the blade 20 a greater distance than the front edge 116, 108, respectively. The positioning of the inner spatula 78 and the outer spatula 76 in this manner provides the gap 86 between the outer surface 34 of the blade 20 and the inner surfaces 124, 114 of the inner spatula 78 and the outer spatula 76, respectively. In the embodiment shown, the gap 86 is a funnel-shaped space that decreases in a direction toward the front edge 116, 108 of the inner and outer spatulas 78, 76 respectively. The feed nozzle 84 is configured to extend into the gap 86 so that the applicator nozzle 88 may deliver the coating material 30 within the funnel-shaped space 86 to form the coating 30. To that end, as the applicator tool 42 traverses along the leading edge 22 of the blade 20, the applicator nozzle 88, the inner spatula 78, and the outer spatula 76 operate together to mold the coating 30 that is subsequently extruded from the gap 86 at an opening 132 near the front edge 108 of the outer spatula 76, ultimately defining the shape of the coating 30. As shown in Figs.5, 7 and 9-10, the inner spatula 78 may include one or more ribs 134a-134d, otherwise referred to as spacers, that are configured to maintain the opening 132 between the outer surface 34 of the blade 20 and the inner spatula 78 and the outer spatula 76, as well as disperse and shape the coating 30 as it is extruded 15   from the opening 132. In this embodiment, the plurality of ribs 134a-134d are disposed beneath the inner surface 124 of the inner spatula 78. As best shown in Figs.9 and 10, the plurality of ribs 134a-134d extend from the inner surface 124 of the inner spatula 78 in a spaced-apart manner. The ribs 134a-134d are generally located adjacent the front edge 116 and may be generally parallel to each other and extend generally from the front edge 116 in a direction toward the rear edge 118 of the inner spatula 78. The plurality of ribs 134a-134d may extend away from the front edge 116 and along the inner surface 124 substantially perpendicular to the front edge 116 of the inner spatula 78. Referring to Figs.5 and 6, the first and second chamfer arms 80, 82 are operatively coupled to the front support 72 of the frame 70 and work together with the outer spatula 76 and the inner spatula 78 to shape the coating material 30 applied to the leading edge 22 of the blade 20. In particular, the first and second chamfer arms 80, 82 are configured to synchronously rotate about the frame 70 of the applicator tool 42 to simultaneously engage the outer spatula 76 on opposing sides of the leading edge 22 of the blade 20. The applicator tool 42 includes a drive 136 that is configured to pivotally move the first and second chamfer arms 80, 82 about the frame 70 to engage with the inner spatula 78 at specific engagement locations along the surfaces 34 of the wind turbine blade 20. In the embodiment shown, the first and second chamfer arms 80, 82 each include an end effector 138 removably attached to a corresponding chamfer arm 80, 82. As shown in Fig. 5, each end effector 138 includes a body 140 for attaching the end effector 138 to a chamfer arm 80, 82, such as with appropriate fasteners 142. Each end effector 138 includes an arm 144 that extends from the body 140 to a compression pad (“pad”) 146 that is configured to engage the inner spatula 78, as shown. Each pad 146 is hollow and extends from an opening at the first end 148 to which the arm 144 is connected to an opening at the opposite second end 150 that is spaced from the arm 144 to define a longitudinal length of the pad 146. As shown in Fig.5, a width of each pad 146 may taper from the first end 148 to the second end 150. As shown in Fig.6, each pad 146 includes a flat surface 152 that is configured to engage the outer surface 112 of the outer spatula 76. Each end effector 138 may be formed, such as using three-dimensional printing methods, from a thermoplastic elastomer or other 16   generally resilient engineering plastics. As a result, the pad 146 of each end effector 138 may generally conform to the profile of the exterior surface 34 of the wind turbine blade 20 to press the inner and outer spatulas 78, 76 thereagainst. With continued reference to Figs.5 and 6, each end effector 138 of the first and second chamfer arms 80, 82 is configured to engage the outer surface 112 of the outer spatula 76 adjacent the front edge 108 to press the inner spatula 78 and the outer spatula 76 against the exterior surface 34 of the wind turbine blade 20 at two specific engagement locations on opposing sides of the leading edge 22 of the wind turbine blade 20. The end effectors 138 are configured to transfer forces from the first and second chamfer arms 80, 82 to produce the outer edges, or chamfer lines 36, without causing damage to the inner or outer spatulas 78, 76 or to the wind turbine blade 20. Referring now to Figs. 5-9, additional details of the applicator nozzle 88 and inner spatula 78 will now be described. The applicator nozzle 88 may be formed from a resilient material such as a thermoplastic elastomer (TPE), for example thermoplastic polyurethane (TPU). As shown in Fig.5, the applicator nozzle 88 includes an nozzle body 154 and an applicator head 156 and is configured to be located within the gap 86 between the inner spatula 78 and the leading edge 22 of the wind turbine blade 20. Specifically, the nozzle body 154 of the applicator nozzle 88 is configured to receive the feed nozzle 84 for attachment, thereby supporting the applicator nozzle 88 within the gap 86. Additionally or alternatively, the applicator nozzle 88 may be attached to the inner spatula 78. Regardless, the applicator nozzle 88 extends from the feed nozzle 84 to position the applicator head 156 adjacent to the one or more ribs 134a- 134d of the inner spatula 78. The one or more ribs 134a-134d serve to distribute the coating material 30 over the surfaces of the wind turbine blade 20 as the coating material 30 is dispensed from the applicator nozzle 88. The applicator head 156 is curved in transverse cross-section to conform to the curved contour of the leading edge 22 of the wind turbine blade 20. The curved profile of the applicator head 156 provides for self-centering of the applicator nozzle 88, and in particular the applicator head 156, over the leading edge 22, thereby providing for an even distribution of coating material 30 onto the leading edge 22 for subsequent spreading by the inner spatula 78. This self-centering configuration of the applicator 17   head 156 prevents uneven application of coating material 30 and the potential coating defects that may stem therefrom. Furthermore, the applicator head 156 of the applicator nozzle 88 is configured to engage with and compress between the surfaces of the wind turbine blade 20 and the inner spatula 78, as shown in Fig.5. As will be described in further detail below, increasing the compression force on the applicator head 156 flattens the applicator head 156, resulting in a lower flow rate of coating material 30 through the applicator nozzle 88 and also flattening the shape or profile of the coating material 30 dispensed from the applicator nozzle 88. Conversely, decreasing the compression force on the applicator head 156 leads to a higher flow rate of coating material 30 through the applicator nozzle 88 and a thicker shape or profile of the coating material 30 dispensed from the applicator head 156. As a result, the coating 30 profile may be tailored to the varying degrees of damage 26 along the length of the wind turbine blade 20, ensuring appropriate coating 30 thickness and profile is applied to areas of greater or lesser damage 26. Fig. 7 illustrates the engagement between the applicator nozzle 88 and the inner spatula 78. As shown, the applicator nozzle 88 is arranged on the inner surface 124 of the inner spatula 78 such that a top surface 158 of the applicator nozzle 88 is engaged against the inner surface 124 of the inner spatula 78. The inner spatula 78 may then fold over the top surface 158 of the applicator nozzle 88 to generally conform the inner spatula 78 to the curved shape of the applicator head 156, as shown. An opposite bottom surface 160 of the applicator nozzle 88 is configured to engage surfaces of the wind turbine blade 20. In that regard, the curved shape of the applicator head 156 is concave to form a recess 162 in the bottom surface 160 of the applicator head 156 that is shaped to receive the leading edge 22 of the wind turbine blade 20. The recess 162 results in the applicator head 156 having a generally thin or narrow outlet end 164, as will be described in further detail below. With continued reference to Fig.7, the applicator nozzle 88 is arranged on the inner surface 124 of the inner spatula 78 such that a central, longitudinal axis A2 of the applicator nozzle 88 is arranged generally in parallel with the central, longitudinal axis A1 of the inner spatula 78. Furthermore, the applicator nozzle 88 is generally centered between the side edges 120 of the inner spatula 78. Notably, the applicator nozzle 88 may be positioned closer to the front edge 116 of the inner spatula 78 than compared 18   to the rear edge 118. In that regard, the applicator head 156 of the applicator nozzle 88 is arranged so as to be in close proximity to the one or more ribs 134a-134d. However, the applicator head 156 may be spaced from the one or more ribs 134a- 134d to form a gap or space therebetween. While the applicator nozzle 88 may be held in the position shown by its attachment to the feed nozzle 84, as described above, the applicator nozzle 88 may be additionally or alternatively be attached to the inner spatula 78 via a pair of attachment holes 166 formed in the inner spatula 78 (e.g., Fig. 9). For example, a band, tie, or clamp may routed through the pair of attachment holes 166 and about the applicator nozzle 88 to removably secure the applicator nozzle 88 to the inner spatula 78. Referring now to Figs.7 and 8, the applicator nozzle 88 includes the nozzle body 154 that is configured to be operatively connected to the feed tube 94 via the feed nozzle 84 and the applicator head 156 that is configured to distribute the coating material 30 onto the wind turbine blade 20. As shown best shown in Fig.8, the nozzle body 154 includes an inlet opening 168 to a main passageway 170 that is configured to receive coating material 30 from the feed nozzle 84. The inlet opening 168 is at an inlet end 172 of the applicator nozzle 88. The feed nozzle 84 is received into the main passageway 170 to place the outlet 98 of the feed nozzle 84 in fluid communication with the main passageway 170 of the applicator nozzle 88 (e.g., Fig. 5). In the embodiment shown, the main passageway 170 may include a shoulder 174 that is configured to abut the feed nozzle 84 to prevent over-insertion of the feed nozzle 84 into the applicator nozzle 88. As described above, the applicator head 156 includes a narrowing profile that is curved in transverse cross-section. Specifically, the applicator head 156 is curved along a transverse axis A3 that is perpendicular to the central, longitudinal axis A2 of the applicator nozzle 88. The curvature of the applicator head 156, resembling an arcuate or half-moon shape, generally corresponds to a curvature of the leading edge 22 of a wind turbine blade 20. Due to the curved profile and resulting recess 162, the applicator head 156 effectively saddles the leading edge 22, ensuring the applicator nozzle 88 stays centered over the leading edge 22 during coating operations. By accommodating the leading edge 22 within the recess 162, the curved profile of the applicator head 156 prevents the applicator nozzle 88 from tilting to either side of the 19   leading edge 22, resulting in a more precise and uniform coating application on the leading edge 22. With reference to Fig. 8, the applicator head 156 fans or flares outwardly from the nozzle body 154 (and central axis A2), on both sides, as the applicator head 156 extends to the outlet end 164 to separate the main passageway 170 into three distinct passageways 176-180 to define at least three separate flows of coating material 30 from the outlet end 164 of the applicator nozzle 88. In that regard, the applicator nozzle 88 is generally symmetrical about the central axis A2. As shown, the applicator head 156 includes a central passageway 176, a first outboard passageway 178, and a second outboard passageway 180. Each passageway 176-180 extends for the length of the applicator head 156 from an inlet opening 182-186, respectively, in fluid communication with the main passageway 170 to an outlet opening 188-192, respectively, at the outlet end 164 of the applicator nozzle 88. To that end, a branching region 194 of the main passageway 170 may gradually widen to accommodate the inlet opening 182-186 of each passageway 176-180, respectively, as shown. The central passageway 176 extends generally along the central axis A2 of the applicator nozzle 88. The first outboard passageway 178 and the second outboard passageway 180 are each angled outwardly relative to the central axis A2 of the applicator nozzle 88. Each passageway 176-180 through the applicator head 156 gradually widens as the passageway 176-180 extends from the respective inlet opening 182-186 to the respective outlet opening 188-192. That is, a transverse cross- sectional area of each passageway 176-180 gradually increases from the inlet opening 182-186 to the outlet opening 188-192, respectively. Furthermore, each passageway 176-180 becomes gradually more flat or narrow as it extends from the inlet opening 182-186 to the outlet opening 188-192, respectively. To that end, a maximum width (measured in a direction generally along the transverse axis A3) of each outlet opening 188-192 is greater than a maximum width of a corresponding inlet opening 182-186. When arranged over the leading edge 22 of a wind turbine blade 20, the central passageway 176 of the applicator head 156 is configured to be centered over the leading edge 22. The first outboard passageway 178 and the second outboard passageway 180 of the applicator head 156 are configured to be located on opposing 20   sides of the leading edge 22 of the wind turbine blade 20. During use, the first and second outboard passageways 178, 180 may experience a majority of the compression force from the chamfer arms 80, 82. This may cause the outlet openings 190, 192 of the first and second outboard passageways 178, 180, respectively, to become more closed compared to the outlet opening 188 of the central passageway 176. As a result, the volume flow rate of coating material through the central passageway 176 is greater comparted to the volume flow rate of coating material through the first and second outboard passageways 178, 180. The greater volume flow rate of coating material through the central passageway 176 creates a coating 30 that, in cross-section, is generally thickest adjacent to the leading edge 22 of the blade 20 and decreases in thickness a generally continuous and smooth manner along the upper and lower surfaces of the blade 20 towards the trailing edge 24, as shown in Fig.3. To that end, the inner spatula 78 and the outer spatula 76 further shape and spread the coating 30 applied to the leading edge 22 of the wind turbine blade 20 once dispensed from the applicator nozzle 88. Fig.9 illustrates the inner spatula 78 which, as briefly described above, includes the front edge 116, the rear edge 118, and opposed side edges 120 that extend between the front and rear edges 116, 118. In particular, the opposed side edges 120 extend outwardly (relative to the central axis A1 of the inner spatula 78) as they extend from the rear edge 118 to the front edge 116, forming a tab 196 and a pair of opposing lobes or flaps 198. In that regard, the inner spatula 78 is generally symmetrical about the central axis A1 of the inner spatula 78. The flaps 198 are configured to fold over the applicator nozzle 88 and into engagement along opposite sides of the wind turbine blade 20, as shown in Figs.5 and 6. To that end, the flaps 198 may be pressed against surfaces of the wind turbine blade 20 by the pair of chamfer arms 80, 82. The tab 196 includes a pair of attachment holes 200 located adjacent the rear edge 118 that may be used to attach the inner spatula 78 to the frame 70 of the applicator tool 42. As shown in Fig. 5, the pair of attachment holes 200 may receive the one or more fastener(s) 92 to secure the inner spatula 78 to the one or more brackets 90. As briefly described above, the inner spatula 78 includes one or more ribs 134a-134d arranged on the inner surface 124 of the inner spatula 78. In the embodiment shown, the inner spatula 78 features a plurality of ribs 134a-134d arranged on its inner surface 21   124, such as seven for illustration. The ribs 134a-134d may be integrally formed with the inner spatula 78 or separately attached to the inner spatula 78. Further, the present disclosure contemplates embodiments with fewer or more ribs 134a-134d, varying in shape, size, and positioning, as appropriate. As shown in Fig.5, the ribs 134a-134d are configured to maintain the opening 132 between the outer surface 34 of the blade 20 and the inner and outer spatulas 78, 76. In that regard, the ribs 134a-134d are configured to engage the outer surface 34 of the blade 20 to define a gap or space between the inner surface 124 of the inner spatula 78 that corresponds to the size of the opening 132. The gap established by each rib 134a-134d corresponds to a height that each rib 134a-134d extends from the inner surface 124 of the inner spatula 78. To that end, the ribs 134a-134d may have the same height or varying heights, as detailed below. With reference to Figs.9 and 10, and as briefly described above, the plurality of ribs 134a-134d may extend from the inner surface 124 of the inner spatula 78 in a spaced- apart manner. In the embodiment shown, the ribs 134a-134d may be spaced evenly apart. The ribs 134a-134d may be generally parallel to each other and extend a length from a first end 202a-202d located adjacent to the front edge 116 of the inner spatula 78 to a second end 204a-204d in a direction toward the rear edge 118 of the inner spatula 78. The first end 202a-202d of each rib 134a-134d may be spaced a distance from the front edge 116 of the inner spatula 78, as shown. The plurality of ribs 134a- 134d may extend away from the front edge 116 and along the inner surface 124 substantially perpendicular to the front edge 116 of the inner spatula 78. In the embodiment shown, the ribs 134a-134d vary in height based on their proximity to the axial center A1 of the inner spatula 78. In that regard, a first rib 134a that is located generally at the axial center A1 of the inner spatula 78 has the greatest height. A pair of second ribs 134b, one rib 134b being positioned outboard on either side of the first rib 134a, are each spaced from the axial center A1 toward a respective side edge 120 of the inner spatula 78. The height of each of the second ribs 134b is less than the height of the first rib 134a. A pair of third ribs 134c are each spaced further from the axial center A1 toward a respective side edge 120 of the inner spatula 78 compared to the second ribs 134b. The height of each third rib 134c being less than the height of the second ribs 134b. Finally, a pair of fourth ribs 134d are each spaced further from the axial center A1 toward a respective side edge 120 of the inner spatula 78 22   compared to the third ribs 134c. To that end, the height of each fourth rib 134d is less than the height of the third ribs 134c. This configuration of ribs 134a-134d results in a tapering in height across the ribs 134a-134d the further away from the axial center A1 that each rib 134a-134d is positioned. With continued reference to Figs.9 and 10, each rib 134a-134d includes a chamfered surface 206a-206d that extends from the first end 202a-202d along a portion of the length of each rib 134a-134d to vary the height of each rib 134a-134d along its length. The chamfered surfaces 206a-206d are configured to engage surfaces of the wind turbine blade 20 during coating operations. As can be seen in Fig.5, an angle of each chamfered surface 206a-206d may generally correspond to the angle at which the applicator tool 42 is positioned to maintain the gap 86. As best shown in Fig.10, each chamfered surface 206a-206d extends from the first end 202a-202d of each rib 134a- 134d to a terminal edge located along a base surface 208a-208d of each rib 134a- 134d to define a length of each chamfered surface 206a-206d. Similar to the height configuration of each rib 134a-134d described above, the length of each chamfered surface 206a-206d gradually decreases the further away each rib 134a-134d is from the axial center A1 of the inner spatula 78. Thus, the chamfered surface 206a of the first, central rib 134a is longest in length while the chamfered surface 206d of the pair of fourth ribs 134d farthest from the axial center A1 is shortest in length. Returning to Figs.5 and 6, an exemplary method of repairing damage 26 to a leading edge 22 of a wind turbine blade 20 will now be described. In that regard, to effectuate maintenance and repair of damage 26 on the leading edge 22 of the wind turbine blade 20, the applicator tool 42 is positioned on the leading edge 22, as shown, and the coating material 30 directed to the feed nozzle 84 for deposit by the applicator nozzle 88 in the funnel-shaped gap 86 between the blade 20 and the inner spatula 78. As the coating material 30 fills the gap 86, the applicator tool 42 may be moved along the leading edge 22 of the blade 20 as demonstrated by directional arrow A4 in Fig.5. As the applicator tool 42 moves, the coating material 30 is forced into the gap 86 toward the front edges 108, 116 of the outer spatula 76 and the inner spatula 78, respectively, and is essentially extruded from the opening 132 at the front edge 108 of the outer spatula 76. In this regard, the height of the coating material 30, or thickness, is dictated by the height profile of the opening 132. As described above, the height profile of the 23   opening 132 corresponds to the height of the ribs 134a-134d. Furthermore, and as a result of the chamfered surfaces 206a-206d of each rib 134a-134d, increasing an angle of the applicator tool 42 relative to the leading edge 22 may also decrease (or increase) the size of the opening 132. To vary the supply rate of the coating material 30 into the gap 86, the applicator tool 42 may be operated to modulate a compressive force acting on the applicator head 156 of the applicator nozzle 88. In that regard, increasing the compression force to compress the applicator head 156 between the applicator tool 42 and surfaces of the wind turbine blade 20 flattens the applicator head 156 and lowers the flow rate of coating material 30 through each nozzle passageway 176-180. Conversely, decreasing the compression force leads to a higher flow rate of coating material 30 through each nozzle passageway 176-180 and thicker coating profiles. Additionally or alternatively, the chamfer arms 80, 82 may be operated to shape the coating material 30 that is being dispensed from the applicator nozzle 88. Upon completing a repair, the applicator nozzle 88, inner spatula 78, and the end effectors 138 may be removed from the applicator tool 42 for disposal. These components may then be replaced with new parts for a subsequent repair activity. In one embodiment, at least the applicator nozzle 88, inner spatula 78, and the end effectors 138 may be formed using a three-dimensional (3D) printing manufacturing method. The term “three-dimensional printing” or “additive manufacturing” or "rapid prototyping” refers to a process of making a three-dimensional solid object of virtually any shape from a digital model.3D printing of the applicator nozzle 88, inner spatula 78, or the end effectors 138 is achieved using an additive process, where successive layers of material are laid down in different shapes to build the structures that define those parts. The term 3D printing, as used herein, may refer to methods such as, but not limited to, selective laser melting (SLM), direct metal laser sintering (DMLS), selective laser sintering (SLS), fused deposition modeling (FDM), and stereolithography (SLA). Further, any type of 3D printing machine that can print the materials described herein with respect to the applicator nozzle 88, inner spatula 78, and the end effectors 138 may be used. 24   As will be understood by a person or ordinary skill in the art, before 3D printing of the applicator nozzle 88, inner spatula 78, or the end effectors 138 may begin, a 3D printing machine being used to form the applicator nozzle 88, inner spatula 78, or the end effectors 138 must first receive a dataset corresponding to those parts. The dataset may be a computer-readable three-dimensional model suitable for use in manufacturing the applicator nozzle 88, inner spatula 78, or the end effectors 138. In particular, the model includes information regarding the characteristics of the applicator nozzle 88, inner spatula 78, or the end effectors 138 from which the 3D printing machine can form those parts. The model may be a 3D printable file such as an Stereolithography file, for example. The dataset may also be in the form of a computer program product embodied on a non-transitory computer readable medium storing executable instructions for forming the applicator nozzle 88, inner spatula 78, or the end effectors 138 using a 3D printing machine. Once the 3D printing machine has been provided with a model or computer-readable program instructions suitable for use in manufacturing the applicator nozzle 88, inner spatula 78, or the end effectors 138, the 3D printing machine may be operated to lay down successive layers of the desired material to build the applicator nozzle 88, inner spatula 78, or the end effectors 138. Computer-readable storage media, which is inherently non-transitory, may include volatile and non-volatile, and removable and non-removable tangible media implemented in any method or technology for storage of data, such as computer- readable instructions, data structures, program modules, or other data. Computer- readable storage media may further include RAM, ROM, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other solid state memory technology, portable compact disc read-only memory (CD-ROM), or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store data and which can be read by a computer. A computer-readable storage medium should not be construed as transitory signals per se (e.g., radio waves or other propagating electromagnetic waves, electromagnetic waves propagating through a transmission media such as a waveguide, or electrical signals transmitted through a wire). Computer-readable program instructions may be downloaded to a computer, another type of programmable data processing apparatus, 25   or another device from a computer-readable storage medium or to an external computer or external storage device or server via a network. Computer-readable program instructions stored in a computer-readable medium may be used to direct a computer, other types of programmable data processing apparatuses, or other devices to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instructions that implement the functions, acts, or operations specified in the flowcharts, sequence diagrams, or block diagrams. The computer program instructions may be provided to one or more processors of a general purpose computer, a special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the one or more processors, cause a series of computations to be performed to implement the functions, acts, or operations specified in the text of the specification, flowcharts, sequence diagrams, or block diagrams. While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments have been described in some detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Moreover, the various features of the invention may be used alone or in any combination depending on the needs and preferences of the user, and the features described in the different embodiments are not dependent on one another for operation of the invention. 26

Claims

Claims 1. An applicator tool (42) for repairing damage (26) to a leading edge (22) of a wind turbine blade (20), comprising: a tool frame (70); an outer spatula (76) operatively supported by the tool frame (70), the outer spatula (76) being configured to engage with an exterior surface (34) of the wind turbine blade (20) to form a gap (86) between the leading edge (22) of the wind turbine blade (20) and the outer spatula (76); a feed tube (84) supported by the tool frame (70) for supplying a coating material to the gap (86); and an applicator nozzle (88) located within the gap (86), the applicator nozzle (88) including a applicator nozzle body (154) configured to be operatively connected to the feed tube (84) and an applicator head (156) configured to distribute the coating material onto the wind turbine blade (20), wherein the applicator head (156) is curved along a transverse axis (A3) that is perpendicular to a longitudinal axis (A2) of the applicator nozzle (88) to generally conform the applicator head (156) to a curved contour of the leading edge (22) of the wind turbine blade (20).

2. The applicator tool (42) according to claim 1, wherein the applicator nozzle (88) comprises a resilient material.

3. The applicator tool (42) according to any one of claims 1 or 2, wherein the applicator head (156) of the applicator nozzle (88) is configured to be compressed between the tool frame (70) and the leading edge (22) of the wind turbine blade (20) to vary a flowrate of the at least three flows of coating material from the applicator nozzle (88).

4. The applicator tool (42) according to any one of the previous claims, wherein the applicator head (156) includes at least three passageways (176-180) that define at least three distinct flows of coating material from the applicator nozzle (88). 27  5. The applicator tool (42) according to claim 4, wherein the at least three passageways (176-180) of the applicator head (156) of the applicator nozzle (88) each include an inlet opening (182-186) and an outlet opening (188-192), wherein a maximum width of each outlet opening (188-192) is greater than a maximum width of each inlet opening (182-186).

6. The applicator tool (42) according to any one of claims 4 or 5, wherein the at least three passageways (176-180) of the applicator head (88) comprise a central passageway (176), a first outboard passageway (178), and a second outboard passageway (180), wherein the first outboard passageway (178) and the second outboard passageway (180) are configured to be located on opposing sides of the leading edge (22) of the wind turbine blade (20).

7. The applicator tool (42) of claim 6, wherein a volume flow rate of coating material through the central passageway (176) is greater than a volume flowrate of material through the first outboard passageway (178) and the second outboard passageway (180).

8. The applicator tool (42) according to any one of claims 7 or 8, wherein the first outboard passageway (178) and the second outboard passageway (180) are angled relative to the longitudinal axis (A2) of the applicator nozzle (88).

9. The applicator tool (42) according to any one of the previous claims, further comprising an inner spatula (78) located between the outer spatula (76) and the applicator nozzle (88), wherein the inner spatula (78) is configured to shape the coating material dispensed from the applicator nozzle (88) into a coating (30) over the leading edge (22) of the wind turbine blade (20).

10. The applicator tool (42) according to claim 9, wherein the inner spatula (78) includes a front edge (116), a rear edge (118), opposed side edges (120), an outer surface (122), and an inner surface (124), the inner surface (124) being configured to engage the applicator nozzle (88) and the wind turbine blade (20). 28  11. The applicator tool (42) according to claim 10, wherein the inner spatula (78) includes one or more ribs (134a-134d) positioned on the inner surface (124) adjacent the front edge (116), wherein the one or more ribs (13a-134d) are configured to define a gap between the exterior surface (34) of the wind turbine blade (20) and the inner surface (124) of the inner spatula (78).

12. The applicator tool (42) according to claim 11, wherein the one or more ribs (134a-134d) are elongate and extend a length from a first end (202a-202d) located adjacent to the front edge (116) of the inner spatula (78) to a second end (204a- 204d) in a direction toward the rear edge (118) of the inner spatula (78).

13. The applicator tool (42) according to claim 12, wherein the one or more ribs (134a-134d) include a chamfered surface (206a-206d) that extends from the first end (202a-202d) along a portion of the length of the one or more ribs (134a-134d) to vary a height that the one or more ribs (134a-134d) extend from the inner spatula (78).

14. The applicator tool (42) according to any one of claims 11-13, wherein the one or more ribs (134a-134d) are integrally formed with the inner spatula (78).

15. The applicator tool (42) according to any one of claims 10-14, wherein the applicator head (156) of the applicator nozzle (88) is positioned along the inner surface (124) of the inner spatula (78) and adjacent the one or more ribs (134a- 134d).

16. The applicator tool (42) according to any one of the previous claims, further comprising a first chamfer arm (80) and a second chamfer arm (82) operatively coupled to the tool frame (70), each being configured to engage an outer surface (112) of the outer spatula (76) to press the outer spatula (76) towards the exterior surface (34) of the wind turbine blade (20) on opposing sides of the leading edge (22) of the wind turbine blade (20).

17. The applicator tool (42) according to claim 16, further comprising an end effector (138) removably attached to each of the first chamfer arm (80) and the 29  second chamfer (82), the end effector (138) including a pad (146) configured to engage the outer spatula (76).

18. The applicator tool (42) according to any one of the previous claims, wherein the applicator nozzle (88) is symmetrical about a central axis (A2) of the applicator nozzle (88).

19. The applicator tool (42) according to any one of the previous claims, wherein the inner spatula (78) is symmetrical about a central axis (A1) of the inner spatula (78).

20. The applicator tool (42) according to any one of the previous claims, wherein the applicator nozzle (88) and / or the inner spatula (78) is a single-use part.

21. A robotic maintenance device (40) including the applicator tool (88) according to any one of the previous claims.

22. A method of repairing damage (26) to a leading edge (22) of a wind turbine blade (20), comprising: providing the applicator tool (42) according to any of claims 1-20; engaging the applicator tool (42) to the exterior surface (34) of the wind turbine blade (20); supplying the coating material to the applicator tool (42); moving the applicator tool (42) along the leading edge (22) of the wind turbine blade (20); and dispensing the coating material from the applicator tool (42) to form a coating (30) over a damaged area (26) of the wind turbine blade (20).

23. The method according to claim 22, further comprising providing a robotic maintenance device (40) including the applicator tool (42) according to any one of claims 1-18.

24. The method according to any one of claims 22 or 23, further comprising operating the first chamfer arm (80) and the second chamfer (82) of the applicator tool 30  (42) to shape the coating material dispensed from the applicator nozzle (88) into the coating (30) over the leading edge (22) of the wind turbine blade (20).

25. The method according to any one of claims 22-24, further comprising disposing of the applicator nozzle (88) and / or the inner spatula (78) after the damaged area (26) of the wind turbine blade (20) has been repaired. 31

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