Film application method and apparatus for large wind turbine blades

Abstract

A method for applying a film (3) to an outer surface (2) of a wind turbine blade (1) or to an inner surface of a casting mould for a wind turbine blade (1), the method comprising: providing a wind turbine blade (1) or a casting mould for a wind turbine blade (1); providing a film (3) on a film roll (8); applying the film (3) from the film roll (8) to an outer surface (2) of the wind turbine blade (1) or to an inner surface of a casting mould for the wind turbine blade (1); and smoothing the applied film (3).

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for applying a film to a large wind turbine blade and to an apparatus for performing such a method.

[0002] The present invention can therefore relate to the technical field of manufacturing wind turbine blades. BACKGROUND

[0003] For large wind turbine blades it is of utmost importance that the outer surface of the wind turbine blade has an excellent finish to ensure a good output. Even small imperfections on the outer surface of the wind turbine blade, such as rough patches, uneven parts or dirt, will significantly reduce the power output of the wind turbine during its entire lifetime.

[0004] One possibility to improve the surface quality of a wind turbine blade is to apply a special paint or to apply a film locally.

[0005] It is known to manually attach a film on a small airfoil surface to locally reproduce natural phenomena and thus to improve the aerodynamic properties of the airfoil itself.

[0006] However, for current wind turbine blades, in particular for offshore wind turbine farms, manual application is disadvantageous due to the risk of detachment caused by human error and due to the vast area that needs to be covered, as such areas typically exceed 750 square meters. SUMMARY

[0007] There can therefore be a need for improving the film application on wind turbine blades.

[0008] According to a first aspect of the present invention, a method for applying a film to an outer surface of a wind turbine blade or to an inner surface of a casting mold for a wind turbine blade is disclosed. The method comprises the steps of: providing a wind turbine blade or a casting mold for a wind turbine blade; providing a film on a film roll; applying the film from the film roll onto the outer surface of the wind turbine blade or onto the inner surface of a casting mold for the wind turbine blade; smoothing the applied film.

[0009] According to another aspect of the present application, a device for applying a film to an outer surface of a wind turbine blade or to an inner surface of a casting mold for a wind turbine blade is provided. The device comprises a base unit, an adjustable arm connected to the base unit, a film roll attached to the adjustable arm, the film roll being configured for providing a film, an application mechanism attached to the adjustable arm, the application mechanism being configured for applying the film to an outer surface of a wind turbine blade or to an inner surface of a casting mold for a wind turbine blade, a smoothing roller attached to the adjustable arm, the smoothing roller being configured for smoothing the film applied to an outer surface of a wind turbine blade or to an inner surface of a casting mold for a wind turbine blade.

[0010] According to the present application, the term "film" can refer to a thin film as used in the aerospace and / or wind energy industry for improving the aerodynamic qualities of an airfoil. For example, such a film can have a smooth surface or have a structured surface, the purpose being to achieve specific properties of the airfoil. By way of example, the structured surface can have a structure which is able to influence the air flow in the boundary region close to the wind turbine blade.

[0011] According to the present application, the term "applying a film" can particularly refer to depositing a leading edge of a film on an outer surface of a wind turbine blade or on an inner surface of a casting mold for a wind turbine blade without the need for pressure or temperature. The application step can be performed manually by an operator, but preferably the application is performed automatically by a device, so that human errors can be minimized.

[0012] According to the present application, it is thus possible to reliably and efficiently apply a film to an outer surface of a wind turbine blade, either by applying the film directly to the outer surface or by applying the film to an inner surface of a casting mold for a wind turbine blade.

[0013] In a first case, the wind turbine blade is already formed and thus the film is applied after the generation of the wind turbine blade itself, so that the outer surface of the wind turbine blade can be improved by the applied film. Thus, applying a film according to the present application on a finished wind turbine blade represents an off-the-shelf and easy way for improving the quality of the wind turbine blade, in particular its aerodynamic properties.

[0014] In a second case, the film is applied to an inner surface of a casting mold for a wind turbine blade before manufacturing the wind turbine blade. Thus, in such a scenario, the film is applied during the manufacturing process, so that the presence of impurities and / or intrusions between the film and the outer surface of the blade is minimized.

[0015] According to embodiments, the method further comprises applying an adhesive and / or a tackifier layer to the outer surface of the wind turbine blade prior to the step of applying the film to the outer surface of the wind turbine blade. In this way the adhesion of the film to the outer surface of the wind turbine blade can be improved.

[0016] In some embodiments, the adhesive and / or the tackifier layer has a thickness comprised between 20 pm and 300 pm.

[0017] According to some embodiments, there is a pressure sensitive tape without adhesive to facilitate the application of the film. Thus, prior to the step of applying the film to the outer surface of the wind turbine blade, the method will comprise the step of applying a pressure sensitive tape to the outer surface of the wind turbine blade. Pressure sensitive tapes are used in the wind turbine industry in combination with leading edge protection solutions for better application of films to the leading edge of wind turbine blades.

[0018] In particular, it can be provided that the pressure sensitive tape is applied together with the film.

[0019] Examples of adhesive layers can be represented by at least one of the following: epoxy resins, silane-modified polymers or silicone-based adhesives. The adhesive can also be a two-component or one-component adhesive that cures upon exposure to moisture, heat or UV light. Instead of liquid adhesives, solid hot-melt adhesive sheets can also be utilized. The solid hot-melt adhesive sheets can be installed on the film roll together with the film to facilitate the application of the method.

[0020] Examples of tackifier layers can be represented by silane coupling agents for bonding different materials.

[0021] According to embodiments, the method further comprises pre-activating the outer surface of the wind turbine blade prior to the step of applying the film to the outer surface of the wind turbine blade. By pre-activating the outer surface of the wind turbine blade, the adhesion of the film to the outer surface of the wind turbine blade can be improved.

[0022] Examples of pre-activating the outer surface of the wind turbine blade are sanding, heating or heat treatment, plasma treatment or UV light treatment. Thus, methods well known in the art can easily be integrated into the method according to the present invention.

[0023] According to embodiments, the method further comprises applying a pressure to the applied film during the smoothing step, wherein preferably it is provided that the pressure is adjustable.

[0024] By applying pressure to the film during the smoothing step of the film on the outer surface of the wind turbine blade, it is possible to improve the adhesion of the film to the outer surface of the wind turbine blade. In addition to this, applying pressure on the film during the smoothing step provides an improved shape fidelity of the film on the outer surface of the wind turbine blade. Also, by applying pressure to the film during the smoothing step of the film on the outer surface of the wind turbine blade, it is possible to improve the adhesion, especially in case a pressure sensitive adhesive tape has been applied on the outer surface of the wind turbine blade before applying the film.

[0025] According to embodiments of the present application, the film can be a pressure sensitive adhesive tape, which is applied directly on the outer surface of the wind turbine blade or on the inner surface of a mold for the wind turbine blade.

[0026] By being able to fine tune the pressure in an adjustable manner, the method can provide an increased adhesion of the film on the outer surface of the wind turbine blade, especially at locations with a complex shape. Also, the adjustable pressure allows calibrating the pressure during the smoothing step in such a way that the wind turbine blade is not structurally damaged during the application and / or smoothing of the film on the outer surface of the wind turbine blade.

[0027] According to embodiments, the method further comprises applying a temperature to the applied film during the smoothing step. Thus, the film can be activated, thereby improving the adhesion.

[0028] According to embodiments, the method further comprises measuring the quality of the applied film after the smoothing step, especially the presence of intrusions between the applied film and the outer surface of the wind turbine blade.

[0029] Thus, it is possible to easily identify whether there are defects in the applied and smoothed film, so that such defects can be quickly treated. In particular, the presence of intrusions, which are material intrusions and / or air intrusions between the film and the outer surface of the wind turbine blade, can have a significant impact on the aerodynamic properties of the wind turbine blade itself. Therefore, it is important to be able to identify and treat such defects.

[0030] According to embodiments, the method can further comprise a step of warning a user if an intrusion and / or air inclusion is detected between the film and the outer surface of the wind turbine blade. Such a warning can be an acoustic and / or visual warning, which is provided to the user by means of a user interface of e.g. a computer, a smartphone, a tablet or another machine.

[0031] According to the method, the measuring is performed by means of a sensor, especially by means of an optical sensor, more especially by means of a camera.

[0032] According to embodiments, the film has a thickness comprised between 20 pm and 800 pm.

[0033] According to embodiments, the method further comprises cutting the film after the step of smoothing the applied film.

[0034] According to embodiments, the film is applied to the outer surface of the wind turbine blade or to the inner surface of the casting mold for the wind turbine blade in a sequential manner by first applying the film to a first section, cutting the film after the step of smoothing on the first section and by performing the steps of the method according to the first aspect of the application on a second section, wherein the second section is adjacent to the first section.

[0035] Thus, it is possible to easily apply the film to the entire outer surface of the wind turbine blade or to the entire inner surface of the casting mold for the wind turbine blade by repeating the application of the film section by section.

[0036] According to embodiments, the method is performed by means of a human machine interface or HMI which is operable by a user. In this way, the execution of the method is particularly efficient since there is no direct human interaction during the film application, thus eliminating possible sources of human error and speeding up the overall process.

[0037] According to embodiments, the base unit and the adjustable arm can form a forklift or gantry crane system with one or more adjustable arms for applying the film.

[0038] According to embodiments, the adjustable arm can comprise a first section which is adjustable along a vertical direction of the base unit and a second section which is adjustable along a direction perpendicular to the vertical direction of the base unit.

[0039] Thus, it is possible to provide an improved positioning system for applying the film.

[0040] According to embodiments, the device further comprises a sensor for measuring the quality of the applied film, in particular the presence of air bubbles or intrusions.

[0041] Thus, it is possible to evaluate the quality of the applied film after the smoothing step.

[0042] The sensor can in particular be an optical sensor, more particularly a camera, which is configured to identify surface defects on the applied film.

[0043] According to embodiments, the device further comprises a memory for saving a CAD model of the outer surface of the wind turbine blade or of the inner surface of the casting mold for the wind turbine blade.

[0044] Thus, it is possible to save for the device the exact geometry of the surface on which the film needs to be applied.

[0045] According to embodiments, the device further comprises a computing unit configured to compute a progress of the application of the film on the outer surface of the wind turbine blade or on the inner surface of the casting unit for the wind turbine blade. In this way, it is possible to improve the quality of the film application process.

[0046] According to embodiments, the device comprises a sensor for measuring the surface on which the film needs to be applied, wherein the computing device computes the curvature of the surface measured by the sensor and stops the process when the curvature exceeds a threshold value.

[0047] According to embodiments, it is also possible that the film is applied and smoothed until the point where the curvature exceeds the threshold value, then the film is cut and the method steps are repeated on an adjacent section of the surface where the curvature is below the threshold value.

[0048] According to embodiments, the device further comprises a cutting device for cutting the film.

[0049] In this application, all method steps can be performed by the device, so that all method features can be used to clarify and limit the scope of the device claims, and device features can be used to clarify and limit the scope of the method claims. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 A schematic diagram showing an embodiment representing a method according to embodiments of the application is shown.

[0051] Figure 2 A device for performing a method according to embodiments of the application is shown.

[0052] Figure 3 A device according to Figure 2 the device performs the method according to Figure 1 on a plurality of sections of a wind turbine blade in a sequential manner.

[0053] The illustrations in the drawings are schematic. It should be noted that in different drawings similar or identically configured elements or features are provided with the same reference signs or with reference signs differing only in the first digit. In order to avoid unnecessary repetition, elements or features already clarified in previous embodiments are no longer clarified again in the subsequent position of the description.

[0054] Furthermore, spatially relative terms, such as "front" and "back", "upper" and "lower", "broadside" and "edge", and the like, can be used herein for the purpose of describing an element's relationship to another element(s) as illustrated in the figures. Such spatially relative terms can be used in accordance with the present application to describe the orientation of an element in use, as opposed to an orientation depicted in the figures. It is to be understood that such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. It is to be understood that all such spatially relative terms refer only to the orientation of the figure shown in the drawing and are not meant to be limiting in nature. DETAILED DESCRIPTION

[0055] Figure 1 schematic representation of a representative embodiment of a method according to the present application. During the description of Figure 1 of the device according to the present application, and vice versa. Figure 2

[0056] Figure 1 The method shown in Fig. 1 is used to apply a thin film 3 to an outer surface 2 of a wind turbine blade 1.

[0057] The present application also includes the case of applying a thin film 3 to an inner surface of a casting mold for a wind turbine blade 1. In such a case, the surface 2 is not an outer surface of a wind turbine blade, but an inner surface of a casting mold for a wind turbine blade 1.

[0058] The method comprises a first step S1 of providing a wind turbine blade 1 or a casting mold for a wind turbine blade.

[0059] In a second step S2, a thin film roll comprising a thin film 3 is provided. The thin film 3 can be a thin film having a specific surface structure, which is preferably intended to improve the aerodynamic properties of the wind turbine blade 1 and thus increase the energy power output and prolong the service life of the wind turbine blade 1.

[0060] The thin film 3 can have a thickness preferably comprised between 20 pm and 800 pm.

[0061] In a further step S3, the outer surface 2 of the wind turbine blade 1 is laminated with an adhesive and / or tackifier layer 4. Such an adhesive and / or tackifier layer 4 can have a thickness comprised between 20 pm and 300 pm.

[0062] Also in step S3, the outer surface 2 of the wind turbine blade 1 can be pre-activated so that the adhesion between the thin film 3 and the outer surface 2 is improved.

[0063] ​Such pre-activation of the outer surface 2 can be done by different means. For example, the pre-activation can comprise sanding the outer surface 2. Other methods for pre-activating the outer surface 2 can also comprise heat treatment, plasma treatment, UV light treatment.

[0064] The above described method for surface application can also be applied to the applied film.

[0065] In a further step S4, the method calculates the surface 2 on which the film 3 has to be applied and smoothed in order to identify possible critical sections by means of the surface parameters. For example, if the surface exceeds a certain threshold value, the method can stop and resume at a point at which the curvature of the surface does not exceed the threshold value.

[0066] In a further step S5, the film 3 is applied to the outer surface 2. By applying the film 3 on the outer surface 2, the film 3 can thus be deposited on the outer surface 2 of the wind turbine blade 1 without using pressure or temperature.

[0067] In a further step S6, the film 3 applied on the outer surface 2 of the wind turbine blade 1 is smoothed such that the film adheres to the outer surface 2 of the wind turbine blade 1.

[0068] During the smoothing step, pressure and / or temperature can be applied to the film 3 such that the adhesion of the film 3 to the outer surface 2 of the wind turbine blade 1 is improved.

[0069] In a further step S7, the quality of the film 3 is controlled by means of a sensor, in particular an optical sensor, more particularly a camera.

[0070] If the sensor identifies any defects in the applied and smoothed film 3, it activates a warning system for warning a user that a defect in the applied and smoothed film 3 has been detected, so that the user can take appropriate countermeasures. In this way, inclusions, intrusions and / or air bubbles between the film 3 and the outer surface 2 of the wind turbine blade 1 can be removed and the quality of the wind turbine blade 1, in particular the quality related to its aerodynamic properties, can be improved.

[0071] Figure 2 An exemplary device 5 for applying a film 3 to the outer surface 2 of a wind turbine blade 1 is shown. As in the case of the device 4, the device 5 can also apply a film 3 to the inner surface of a cast mold for a wind turbine blade 1. Figure 1

[0072] ​The device 5 comprises a base unit 6. The base unit 6 can be, for example, a fork lift or a gantry system, such as such systems known in the wind turbine blade manufacturing prior art. In the base unit 6 there can be a control unit (not shown) for controlling the device 5, wherein a surface model, for example a CAD model, of the surface 2 on which the film has to be applied and smoothed is provided. Thus, the film 3 can be applied and smoothed by setting the correct parameters for the process and the user of the device 5 can also be warned if the curvature of the surface exceeds a certain threshold, so that it is not possible to apply and smooth the film 3.

[0073] The base 6 comprises wheels 61 for moving the device 5 during the process. The wheels 61 can be replaced by a caterpillar system allowing the device 5 to move on the workshop floor.

[0074] The device 5 further comprises an adjustable arm 7, which is preferably provided as a robot arm. The adjustable arm 7 comprises a first part 71 allowing a movement in a vertical direction with respect to the base 6 and a second part 72 allowing a movement in a direction perpendicular to the vertical direction with respect to the base 6.

[0075] There is a film roll 8 attached to the adjustable arm 7, on which the film 3 is provided.

[0076] A smoothing roller 9 is also attached to the adjustable arm 7. The smoothing roller 9 according to the present embodiment is configured to both apply and smooth the film 3 on the outer surface 2 of the wind turbine blade 1. To this end, the smoothing roller 9 can apply a variable pressure on the film 3 during the application and smoothing, wherein the pressure is controlled by a control unit (not shown) placed in the base unit. In particular, the pressure can be changed if an adaptation to different blade types and / or geometries in different areas is required.

[0077] Furthermore, the smoothing roller 9 can have a heat unit (not shown) configured for heating the film 3 during the application and smoothing. In particular, the roller 9 can be used to smooth the film 3 if such film 3 comprises a pressure sensitive adhesive tape.

[0078] The device further comprises an activation device 11 configured for activating the outer surface 2 of the wind turbine blade 1 before applying the film 3.

[0079] The activation device 11 can be, for example, a sanding unit, a UV light treatment unit, a heat treatment unit or a plasma treatment unit.

[0080] Furthermore, there is an adhesive and / or tackifier layer unit 10 for applying an adhesive and / or tackifier layer 4 to the outer surface 2 of the wind turbine blade 1 before applying the film 3.

[0081] Furthermore, the apparatus 5 comprises a sensor unit 12 for measuring the quality of the film 3 once it has been applied and smoothed on the outer surface 2 of the wind turbine 1.

[0082] The sensor unit 12 is preferably an optical sensor and more preferably a camera.

[0083] If the sensor unit 12 detects any defects, it can report them to a control unit (not shown) placed inside the base unit 6, so that the user can take the necessary actions for correcting the defects.

[0084] Furthermore, a cutting apparatus 13 is attached to the adjustable arm 7. The cutting apparatus 13 is configured to cut the film roll after the end of the process of applying and smoothing the film 3.

[0085] Figure 3 It is shown how the apparatus according to Figure 2 performs the method according to Figure 1 on different adjacent segments.

[0086] Different segments 15A, 15B... 15G of the outer surface 2 of the wind turbine blade 1 are shown in Figure 3 As schematically represented, the apparatus 5 first applies and smooths the film 3 on the segment 15A. Once the segment 15A has been provided with the film 3, in step S8, the apparatus 5 cuts the film 3 with the cutting apparatus 13.

[0087] The apparatus 5 then moves along the direction 14 to the next segment 15B, where the method according to Figure 1 is repeated. After the segment 15B, the segment 15C is treated in the same way and the process is repeated until all segments of the outer surface 2 of the wind turbine blade 1 are provided with the film 3.

[0088] In this way, the film is applied and smoothed on the entire outer surface 2 of the wind turbine blade 1 in an easy and reliable way.

[0089] Independent of the grammatical terms used, individuals with male, female or other gender identities are included within the terms.

Claims

1. A method for applying a thin film (3) to the outer surface (2) of a wind turbine blade (1) or to the inner surface of a casting mold for a wind turbine blade (1), the method comprising: Provide wind turbine blades (1) or casting molds for wind turbine blades (1); Provide film (3) on film roll (8); The film (3) is applied from the film roll (8) to the outer surface (2) of the wind turbine blade (1) or to the inner surface of the casting mold for the wind turbine blade (1); Smooth the applied film (3).

2. The method according to claim 1, wherein, Prior to the step of applying the film (3) to the outer surface (2) of the wind turbine blade (1), the method further includes: Apply an adhesive and / or tackifier layer (4) to the outer surface (2) of the wind turbine blade (1).

3. The method according to claim 2, wherein, The adhesive and / or tackifier layer (4) has a thickness ranging from 20 µm to 300 µm.

4. The method according to any one of claims 1 to 3, wherein, Prior to the step of applying the film (3) to the outer surface (2) of the wind turbine blade (1), the method further includes: The outer surface (2) of the wind turbine blade (1) is pre-activated.

5. The method according to claim 4, wherein, The pre-activation step is performed by at least one of the following means: Grinding, heat treatment, plasma treatment, UV light treatment.

6. The method according to any one of claims 1 to 5, wherein, The method further includes: Pressure is applied to the applied film (3) during the smoothing step, wherein preferably the pressure is adjustable.

7. The method according to any one of claims 1 to 6, wherein, The method further includes: Temperature is applied to the applied film (3) during the smoothing step.

8. The method according to any one of claims 1 to 7, wherein, The method further includes: After the smoothing step, the mass of the applied film (3) is measured, particularly the presence of intrusions between the applied film (3) and the outer surface (2) of the wind turbine blade.

9. The method according to claim 8, wherein, The measurement is performed by means of a sensor (12), particularly an optical sensor, and even more particularly by means of a camera.

10. The method according to any one of claims 1 to 9, wherein, The film (3) has a thickness ranging from 20 µm to 800 µm.

11. The method according to any one of claims 1 to 10, wherein, The method further includes cutting the film (3) after smoothing the applied film (3).

12. An apparatus (5) for applying a thin film to the outer surface (2) of a wind turbine blade (1) or to the inner surface of a casting mold for a wind turbine blade (1), said apparatus (5) comprising: Base unit (6); Adjustable arm (7), which is connected to the base unit (6); A film roll (8) is attached to the adjustable arm (7) and is configured to provide a film (3). An application mechanism is attached to the adjustable arm (7) and is configured to apply the film (3) to the outer surface (2) of the wind turbine blade (1) or to the inner surface of the casting mold for the wind turbine blade (1). A smoothing roller (9) is attached to the adjustable arm (7) and is configured to smooth a film (3) applied to the outer surface (2) of a wind turbine blade (1) or to the inner surface of a casting mold for a wind turbine blade (1).

13. The device (5) according to claim 12, wherein, The device (5) also includes a sensor (12) for measuring the mass of the applied and smoothed film (3), particularly the presence of bubbles or intrusions.

14. The device (5) according to claim 12 or 13, wherein, The device (5) also includes a memory for storing a CAD model of the outer surface (2) of the wind turbine blade (1) or the inner surface of the casting mold for the wind turbine blade (1).

15. The device (5) according to any one of claims 12 to 14, wherein, The device (5) also includes a cutting device (13) for cutting the film (3).

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