GB2552835A - Method and apparatus for making a layer of material to be applied a leading edge of a wind turbine blade - Google Patents

Method and apparatus for making a layer of material to be applied a leading edge of a wind turbine blade Download PDF

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Publication number
GB2552835A
GB2552835A GB1613855.4A GB201613855A GB2552835A GB 2552835 A GB2552835 A GB 2552835A GB 201613855 A GB201613855 A GB 201613855A GB 2552835 A GB2552835 A GB 2552835A
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United Kingdom
Prior art keywords
layer
flexible substrate
leading edge
configuration
substrate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
GB1613855.4A
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GB201613855D0 (en
Inventor
Stenbaek Nielsen Knud
Sylvester Nielsen Kim
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Vestas Wind Systems AS
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Vestas Wind Systems AS
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Publication date
Application filed by Vestas Wind Systems AS filed Critical Vestas Wind Systems AS
Priority to GB1613855.4A priority Critical patent/GB2552835A/en
Publication of GB201613855D0 publication Critical patent/GB201613855D0/en
Priority to EP16819811.7A priority patent/EP3389990B1/en
Priority to PCT/DK2016/050432 priority patent/WO2017101948A1/en
Publication of GB2552835A publication Critical patent/GB2552835A/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C9/00—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important
    • B05C9/02—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important for applying liquid or other fluent material to surfaces by single means not covered by groups B05C1/00 - B05C7/00, whether or not also using other means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C1/00—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating
    • B05C1/02—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to separate articles
    • B05C1/027—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to separate articles only at particular parts of the articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C13/00—Means for manipulating or holding work, e.g. for separate articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C3/00—Apparatus in which the work is brought into contact with a bulk quantity of liquid or other fluent material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C3/00—Apparatus in which the work is brought into contact with a bulk quantity of liquid or other fluent material
    • B05C3/20—Apparatus in which the work is brought into contact with a bulk quantity of liquid or other fluent material for applying liquid or other fluent material only at particular parts of the work
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
    • B05C5/02—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work the liquid or other fluent material being discharged through an outlet orifice by pressure, e.g. from an outlet device in contact or almost in contact, with the work
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/28—Processes for applying liquids or other fluent materials performed by transfer from the surfaces of elements carrying the liquid or other fluent material, e.g. brushes, pads, rollers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00—Moulds or cores; Details thereof or accessories therefor
    • B29C33/30—Mounting, exchanging or centering
    • B29C33/308—Adjustable moulds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C63/00—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor
    • B29C63/02—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor using sheet or web-like material
    • B29C63/04—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor using sheet or web-like material by folding, winding, bending or the like
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D1/00—Wind motors with rotation axis substantially parallel to the air flow entering the rotor 
    • F03D1/06—Rotors
    • F03D1/065—Rotors characterised by their construction elements
    • F03D1/0675—Rotors characterised by their construction elements of the blades
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
    • B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
    • B29C41/08—Coating a former, core or other substrate by spraying or fluidisation, e.g. spraying powder
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C63/00—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor
    • B29C63/0073—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor of non-flat surfaces, e.g. curved, profiled
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/08—Blades for rotors, stators, fans, turbines or the like, e.g. screw propellers
    • B29L2031/082—Blades, e.g. for helicopters
    • B29L2031/085—Wind turbine blades
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2230/00—Manufacture
    • F05B2230/30—Manufacture with deposition of material
    • F05B2230/31—Layer deposition
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Wind Motors (AREA)

Abstract

A method of making a layer of cured material for application to a leading edge of a wind turbine blade, the method comprising: arranging a flexible substrate 326 in an application configuration (see figure 6) in which a layer-supporting surface 327 of the flexible substrate is substantially flat; applying a layer of liquid material (50, see fig 5) to the layer-supporting surface; reconfiguring the flexible substrate into a curing configuration (see figure 7) in which a part of the layer-supporting surface that supports the layer of material is curved; and curing the layer of material with the flexible substrate in the curing configuration to form a curved layer of cured material on the flexible substrate. An apparatus for use in the above method may have a concave curved surface or a gutter shaped formation. Finally, the flexible substrate may comprise a flexible membrane.

Description

(54) Title of the Invention: Method and apparatus for making a layer of material to be applied a leading edge of a wind turbine blade
Abstract Title: Method and apparatus for applying a layer of material to a leading edge of a wind turbine blade.
(57) A method of making a layer of cured material for application to a leading edge of a wind turbine blade, the method comprising: arranging a flexible substrate 326 in an application configuration (see figure 6) in which a layersupporting surface 327 of the flexible substrate is substantially flat; applying a layer of liquid material (50, see fig 5) to the layer-supporting surface; reconfiguring the flexible substrate into a curing configuration (see figure 7) in which a part of the layer-supporting surface that supports the layer of material is curved; and curing the layer of material with the flexible substrate in the curing configuration to form a curved layer of cured material on the flexible substrate. An apparatus for use in the above method may have a concave curved surface or a gutter shaped formation. Finally, the flexible substrate may comprise a flexible membrane.
Figure GB2552835A_D0001
Figure 1
300 /6
Figure GB2552835A_D0002
Figure 1
Figure GB2552835A_D0003
Figure 2
Figure 3
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Figure GB2552835A_D0004
Figure GB2552835A_D0005
Figure 4 Figure 5
Figure GB2552835A_D0006
Figure 6
Figure GB2552835A_D0007
Figure GB2552835A_D0008
Figure 8a
50b
Figure GB2552835A_D0009
50a
Figure 8b
3/6
325c
Figure GB2552835A_D0010
Figure 9
Figure GB2552835A_D0011
Figure 10a
Figure GB2552835A_D0012
Figure 10b
330
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Figure GB2552835A_D0013
Figure GB2552835A_D0014
Figure 12
Figure GB2552835A_D0015
Figure 13
Figure GB2552835A_D0016
342
338
Figure 14
6/6
Figure GB2552835A_D0017
338
Figure 15
Figure GB2552835A_D0018
Figure 16
326a
Figure GB2552835A_D0019
Figure GB2552835A_D0020
Figure 17
Method and apparatus for making a layer of material to be applied a leading edge of a wind turbine blade
Field of the invention
The invention relates to a method and apparatus for making a layer of material to be applied to a leading edge of a wind turbine blade, and to a method and apparatus for applying a layer of material to a leading edge of a wind turbine blade.
Background to the invention
It is often necessary to apply layers of material such as paint, resin, adhesives, precured polymer tapes, or other pre-shaped layers to the leading edge of a wind turbine blade during its manufacture and during on-site maintenance. For example, an erosionresistant paint or leading edge protection layer is applied to the leading edge of the blade during manufacture to resist erosion of the leading edge due to precipitation and airborne particles while the blade is in use. During use, the erosion-resistant paint can be gradually eroded and it can therefore be necessary to re-apply the paint to the leading edge of the wind turbine blade on-site.
It is important that such paint is applied uniformly to the surface of the wind turbine blade and that the thickness of the layer is carefully controlled. If the paint is not uniform, some regions will be too thin, and will not provide sufficient erosion resistance. An even layer is particularly important at the leading edge of the blade, because any roughness or inconsistencies at the leading edge will disturb the air flow around the blade and lead to a reduction in the aerodynamic efficiency of the wind turbine.
The erosion-resistant paint is typically applied by spraying or using a brush or roller. However, it is difficult to apply such layers of material evenly and smoothly to the curved surface at the leading edge of a wind turbine blade. For example, in a typical twocomponent erosion-resistant paint, the paint is very fluid in its initial state when it has just been mixed, and has a low viscosity. When applied to the curved surface of the leading edge, the low viscosity means that the paint tends to run down the contours of the curves making it difficult to apply evenly. Shortly after the paint has been mixed (in some cases, within a few minutes), the paint begins to gel and the viscosity of the paint increases; however, in this gelled state it is too viscous to be spread evenly and smoothly. Given that the paint has a low gel point (meaning that it gels quickly) there is therefore only a very short window in which the paint is at a viscosity that is suitable for even spreading.
Thus, it is very difficult to achieve a paint viscosity that allows even application of the paint to the leading edge of the wind turbine blade.
Pre-cured polymer tapes are typically attached manually using adhesives that are applied to a blade-facing surface of the tape. However, applying tapes in this way requires significant skill and diligence. If the tape is not skilfully applied, the tape may be uneven or damaged.
It would be desirable to overcome or mitigate the problems described above.
Summary of the invention
Against this background, from a first aspect, the invention resides in a method of making a layer of cured material for application to a leading edge of a wind turbine blade, the method comprising: arranging a flexible substrate in an application configuration in which a layer-supporting surface of the flexible substrate is substantially flat; applying a layer of liquid material to the layer-supporting surface; reconfiguring the flexible substrate into a curing configuration in which a part of the layer-supporting surface that supports the layer of material is curved; and curing the layer of material with the flexible substrate in the curing configuration to form a curved layer of cured material on the flexible substrate.
The method produces a flexible substrate supporting a cured or semi-cured layer that is pre-cured into a curved shape. Said another way, the layer is configured such that if the layer were to be laid flat after curing, the upper and lower surfaces of the layer would exhibit different stresses. In particular, one surface would exhibit a tensile stress while the other would exhibit a compressive stress.
When the resulting layer is applied to a leading edge of a wind turbine blade, it is forced to adopt a curved configuration, similar to the configuration it adopted as it was cured. If the layer had been cured in a flat configuration, this curved configuration would lead to a difference in the stress state in the upper and lower surfaces of the layer, which would risk breakage of the layer is it is applied, and/or increase the chance of the layer peeling away after application. It would also lead to a decreased ability to absorb precipitation strikes and hence a decreased erosion-resistance performance.
However, because the layer produced by the method of the invention is pre-cured into a curved shape, the layer will be subject to a lower stress than would otherwise have been present when the film is applied to the leading edge. Thus, the stress differential at the surfaces of the layer is removed, or at least reduced, leading to a more robust layer that provides more effective erosion resistance.
For particular ease of application of the liquid material, the step of arranging the flexible substrate in the application configuration may comprise arranging at least a part of the flexible substrate on a flat surface.
The step of arranging the flexible substrate in the curing configuration may comprise arranging at least a part of the flexible substrate on a curved surface.
The step of reconfiguring the flexible substrate may comprise moving the flexible substrate from a first support structure configured to support the flexible substrate in the application configuration to a second support structure configured to support the flexible substrate in the curing configuration. In another embodiment, the step of reconfiguring the flexible substrate may comprise moving the flexible substrate between different parts of the same support structure.
The layer of liquid material applied to the layer-supporting surface may define a footprint that is elongate along a longitudinal axis, and the step of reconfiguring the flexible substrate into the curing configuration may comprise causing at least a part of the flexible substrate to fold about the longitudinal axis. In this way, the layer may be elongate to follow the elongate leading edge of a wind turbine blade, and may be easily shaped so as to mimic the curved shape of the leading edge during curing by a simple folding action.
The step of applying a layer of liquid material to the layer-supporting surface may comprise applying a liquid layer of substantially uniform thickness to the layer-supporting surface. This is particularly advantageous as it means that, once the layer of material is cured, it provides a cured layer of substantially uniform thickness, which, when applied to the leading edge, provides a smooth profile.
The step of applying a liquid layer of substantially uniform thickness may comprise: providing a liquid container comprising dispensing slot of substantially uniform height; and allowing liquid to flow from the liquid container onto the layer-supporting surface via the dispensing slot. Such a method of dispensing the layer is particularly quick and inexpensive whilst maintaining careful control of the layer thickness.
The method may comprise applying a layer of liquid material having a thickness less than approximately 5 mm.
So that the thickness of the layer is not altered due to flow of the liquid layer as it is reconfigured into the curing configuration, the method may comprise allowing the layer of liquid material to cure partially to increase the viscosity of the liquid layer before reconfiguring the flexible substrate into the curing configuration.
For a fast manufacturing process, the method may comprise heating the layer of material while the flexible substrate is in the curing configuration to cure the layer of liquid material.
The liquid material may comprise a curable liquid paint or resin.
The invention also extends to a method of applying a layer of material to a leading edge of a wind turbine blade, the method comprising making a layer of cured material according the method described above, and applying the layer of cured material to the leading edge.
The step of applying the layer of cured material to the leading edge of the wind turbine blade may comprise wrapping a flexible substrate supporting the layer of cured material around the leading edge, and transferring the layer of material from the flexible substrate to the leading edge of the wind turbine blade. Wrapping the flexible substrate and hence the layer of cured material around the leading edge in this way is a particularly effective means of transferring the layer of material securely to the wind turbine blade, with minimal disturbance to the layer. The same flexible substrate part may be used both to cure the layer of material and to transfer the layer of material to the leading edge; alternatively, the layer of material may, for example, be cured on a first flexible substrate part and transferred to a second flexible substrate part for application to the leading edge.
The step of wrapping the flexible substrate around the leading edge may comprise: arranging the flexible substrate in relation to the leading edge of the wind turbine blade with the flexible substrate in a presentation configuration such that an initial area of contact is defined between the layer of material and the leading edge; and reconfiguring the flexible substrate into a transfer configuration in which the flexible substrate adopts the contours of the leading edge by increasing the area of contact between the layer of material and the leading edge. Gradually increasing the area of contact in this way tends to cause air to be effectively expelled towards the edges of the membrane as the area of contact grows, which guards against air becoming trapped between the layer of material and the leading edge of the wind turbine blade, thereby improving the adhesion of the layer and the aerodynamic performance of the leading edge.
To facilitate adhesion of the layer of material to the leading edge, the method may comprise applying an adhesive layer to the layer of cured material before applying the layer of cured material to the leading edge of a wind turbine blade.
For particularly effective bonding, the adhesive layer may be a layer of liquid adhesive, and the layer of cured material and the layer of liquid adhesive may be layers of substantially the same material in cured and liquid states respectively.
The layer of material may be applied to the blade in-situ on a wind turbine.
The invention further extends to apparatus for making a cured layer of material for application to a leading edge of a wind turbine blade, the apparatus comprising a flexible substrate that is reconfigurable between an application configuration in which a layersupporting surface of the flexible substrate is substantially flat and a curing configuration in which the layer-supporting surface is substantially curved, and a substrate support configured to support the flexible substrate in the application configuration and the curing configuration.
The substrate support may comprise a flat surface for supporting the flexible substrate in the application configuration.
Additionally or alternatively, the substrate support may comprise a curved surface for supporting the flexible substrate in the application configuration.
The curved surface may be concave. By providing a concave surface, the layer of material may be cured into the desired shape on the flexible substrate such that a concave surface of the layer of material faces outwardly, away from the substrate. In this way, the surface that was concave during curing can be presented to a leading edge of a blade without the need to rearrange the layer of material any further. Alternatively, the curved surface may be convex, in which case the layer of material may need to be removed from the substrate and rearranged before application to the leading edge.
The curved surface may be defined by a substantially gutter-shaped formation on the substrate support.
The substrate support may comprise a first support structure configured to support the flexible substrate in the application configuration and a second support structure configured to support the flexible substrate in the curing configuration.
The flexible substrate may comprise a flexible membrane. The flexible substrate may have thickness that is less than approximately 2 mm. The flexible substrate may be made of a material selected from the group of: silicon rubber, polyurethane, polyethylene, polypropylene or nylon. By flexible is meant that the substrate can change shape upon relative movement of the flexible substrate and the leading edge towards one another without breaking.
For particular ease of application of the layer of material to the flexible substrate, the apparatus may comprise an applicator for applying a layer of material to the flexible substrate. For particularly careful control of the thickness of the layer of material, the applicator may comprise a container provided with slot for dispensing the material onto the flexible substrate.
The invention also encompasses apparatus for applying a layer of material to a leading edge of a wind turbine blade, the apparatus comprising the apparatus described above, wherein: the flexible substrate is further reconfigurable into a presentation configuration in which, in use, a layer of material supported by the flexible substrate can be offered up to the leading edge of the wind turbine blade to define an initial area of contact between the layer of material and the leading edge, and a transfer configuration in which the flexible substrate adopts the contours of at least a portion of the leading edge; and the substrate support is further configured to support the flexible substrate in the presentation and transfer configurations such that the flexible substrate can be reconfigured from the presentation configuration into the transfer configuration by increasing the area of contact between the layer of material and the leading edge upon relative movement of the flexible substrate and the leading edge towards one another.
Such an apparatus provides a gentle wrapping motion that minimises the chance of damage to the layer of material during application. Gradually increasing an area of contact tends to cause air to be effectively expelled towards the edges of the membrane as the area of contact grows, which guards against air becoming trapped between the layer of material and the leading edge of the wind turbine blade, thereby improving the adhesion of the layer and the aerodynamic performance of the leading edge. Furthermore, in cases where a liquid adhesive layer is applied to the layer of material, at an end region of the layer, the wrapping motion also causes a small amount of liquid adhesive material in the edge region to be displaced outwards so that the material in the edge region tapers to zero thickness. This tapering thickness in the edge region of the layer, avoids any ‘step’ on the leading edge where the layer of material ends, which improves the aerodynamic performance of the blade.
For particular ease of transfer of the layer to the leading edge, the substrate support may comprise a resistive element that may be configured to apply a resistive force to push the flexible substrate against the leading edge as the flexible substrate and the leading edge are moved towards one another.
The flexible substrate may comprise first and second flexible substrate parts, the first flexible substrate part being reconfigurable into the application and curing configurations and the second flexible substrate part being reconfigurable into the presentation and transfer configurations. Alternatively, the flexible substrate may comprise a single flexible substrate part may be reconfigurable into the application, curing, presentation and transfer configurations.
The substrate support may comprise a first substrate support structure configured to support the flexible substrate in the application and curing configurations and a second substrate support structure configured to support the flexible substrate in the presentation and transfer configurations.
The invention extends further to apparatus for applying a layer of material to a leading edge of a wind turbine blade, the apparatus comprising a flexible substrate and a layer of cured or semi-cured material for application to a leading edge of a wind-turbine blade, the layer being supported by the flexible substrate and having a substrate-facing surface and an outward-facing surface, wherein the flexible substrate is configurable into an application configuration in which the substrate adopts the contours of the leading edge of a wind turbine blade, and wherein the layer of material is configured such that, if the flexible substrate is arranged in a flat configuration, an inherent stress in the outwardfacing surface of the layer is tensile and an inherent stress in the substrate-facing surface of the layer is compressive.
The layer of material is configured to have inherent stresses when laid flat, but to have substantially no inherent stress when it is arranged with the outward-facing surface in a concave configuration. In this way, when the layer of material is applied to the leading edge, and the outward-facing surface lies against the leading edge to adopt a concave configuration, there will be no inherent stress in the layer, which improves the energyabsorption properties of the layer and thereby improves its erosion-resistance.
The layer of material may comprise a layer of cured or semi-cured paint. The paint may be an erosion-resistant paint. The layer of material may have a thickness less than 5 mm. The layer of material may have a thickness less than 2 mm.
Brief description of the drawings
In order that the present invention may be more readily understood, examples of the invention will now be described with reference to the remaining figures, in which:
Figure 1 is a perspective view of apparatus for making a layer of cured or semicured material and applying the layer to a leading edge of a wind turbine blade according to an aspect of the invention;
Figure 2 is a schematic view of an applicator forming part of the apparatus of Figure 1;
Figure 3 is a perspective view of a dispensing container forming part of the applicator of Figure 2;
Figure 4 is a cross-section view of a flexible substrate forming a part of the apparatus of Figure 1 supported by a first support structure forming a part of the apparatus of Figure 1 in an application configuration and ready to receive a layer of material;
Figure 5 is a cross-section view of the flexible substrate of Figure 4 with a layer of liquid material being applied using the applicator of Figures 2 and 3;
Figure 6 is a perspective view of the flexible substrate of Figure 5 with the layer of liquid material in place;
Figure 7 is a cross-section view of the flexible substrate supported by a second support structure forming a part of the apparatus of Figure 1 in a curing configuration during curing of the liquid;
Figures 8a and 8b are cross-section views of the flexible substrate supporting the cured layer of material in curved and flat configurations respectively;
Figure 9 is a perspective view of a wind turbine blade and apparatus which, in combination with the apparatus of Figure 1, forms apparatus for applying a layer of material to the leading edge of the wind turbine blade according to another aspect of the invention;
Figures 10a and 10b are cross-section views of a substrate support forming part of the apparatus of Figure 9 in a presentation configuration and a transfer configuration respectively;
Figure 11 is a cross-section view of a flexible substrate supporting a cured layer of material with a layer of liquid adhesive applied;
Figure 12 is a cross-section view of the apparatus of Figure 9 ready to apply a layer of material to the leading edge of a wind turbine blade;
Figure 13 is a cross-section view of the substrate support with the substrate in a presentation configuration, with the layer of material in contact with the leading edge of the blade;
Figure 14 is a cross-section view of the substrate support with the substrate in a transfer configuration in which the substrate has adopted the contours of the leading edge of the wind turbine blade such that the layer of material is wrapped around the leading edge; and
Figure 15 is a cross-section view of the leading edge of the wind turbine blade after the substrate support has been removed;
Figure 16 is a cross-section view of layer of material applied to the leading edge of the wind turbine blade; and
Figure 17 is a perspective view of an alternative flexible substrate forming part of apparatus for making a layer of cured or semi-cured material and applying the layer to a leading edge of a wind turbine blade, the alternative flexible substrate comprising first and second flexible substrate parts.
Detailed description of embodiments of the invention
Figure 1 illustrates apparatus 300 for making a layer of cured material and applying that layer to a leading edge of a wind turbine blade (not shown in Figure 1).
The layer of cured material 50 may take many different forms. For example, the layer of material 50 may be a paint, or it may be another material such as a resin (for example a polyurethane, epoxy or methacrylate resin) or other coating. The layer may be fully cured or it may be partially cured. In the forgoing exemplary embodiment, the layer of material 50 takes the form of a film of cured paint.
The apparatus 300 comprises a substrate support 325 comprising first, second and third support structures 325a, 325b, 325c a substrate 326 in the form of a flexible membrane and an applicator 324.
An upper surface 327 of the flexible membrane 326 defines a layer-supporting surface that supports the layer of material when the apparatus is in use. The first support structure 325a is configured to support the membrane 326 in an application configuration in which a part of the layer-supporting surface 327 to which the layer of material 50 is to be applied is substantially flat. With the membrane in this application configuration, the applicator 324 is used to apply a layer of liquid material, such as liquid paint, to the membrane when the membrane is in this application configuration. The second support structure 325b is configured to support the membrane 326 in a curing configuration in which a part of the layer-supporting surface 327 of the membrane 326 to which the layer of material 50 is to be applied is substantially curved. With the membrane in this curing configuration, the layer of liquid material is cured into a concave shape. The cured layer is then applied to a leading edge of a wind turbine blade using the third substrate support structure 325c, where it will adopt a curved shape similar to the shape that it adopted during curing.
In this way, first and second substrate support structures 325a, 325b, the membrane 326 and the applicator 324 define apparatus for making the cured or semi-cured layer, and the membrane 326 and third substrate support structure 325c define apparatus for applying the layer to a leading edge of a wind turbine blade.
Turning first to the apparatus for making the cured or semi-cured layer, and considering the membrane 326 in more detail, the flexible membrane 326 is made of a soft, flexible material, such as a silicon rubber or a polyolefin. Alternatively, the membrane 326 may be made from another suitable plastics material such as polyurethane, polyethylene, polypropylene or nylon. The membrane has a thickness of less than 2mm, and preferably less than 1mm. In this way, the membrane is flexible so as to allow easy reconfiguration of the membrane.
The layer-supporting surface 327 of the flexible membrane 326 is smooth and non-stick, so as to provide a smooth finish to the layer of material after application to the leading edge, and so as to facilitate transfer from the flexible membrane 326 to the leading edge.
Turning to the substrate support 325, the support 325 comprises first and second support structures 325a, 325b, each having a substrate-supporting surface 329a, 329b.
The first support structure 325a is configured to support the membrane 326 in an application configuration in which a part of the layer- supporting surface 327 of the membrane 326 to which the layer of material 50 is to be applied is substantially flat. To this end, the first support structure comprises a substantially flat substrate-supporting surface 329a.
The second support structure 325b is configured to support the membrane 326 in a curing configuration in which a part of the layer-supporting surface 327 of the membrane 326 to which the layer of material 50 is to be applied is substantially curved, and in particular in this example is curved in a concave configuration. To this end, the substratesupporting surface 329b comprises a curved portion 331. More specifically, the curved portion 331 defines a gutter-shaped formation having a concave surface that is curved about a longitudinal axis L.
Figures 2 and 3 illustrate in further detail the applicator 324 for applying a layer of material to the flexible membrane 326.
Referring to Figure 2, the applicator 324 comprises a dispensing container 40 for holding the material to be applied, a storage volume 42 for storing the material and a transmission means 44 for transmitting the material from the storage volume 42 to the dispensing container 40.
As seen in Figure 3, the dispensing container 40 is formed as a frame, with four side walls and no top or bottom surface. A front wall of the dispensing container comprises a slot 46. In use, material is dispensed through the slot 46 onto the flexible membrane 326 (not visible in Figure 3).
In the embodiment shown, the storage volume 42 is a substantially cylindrical tube that is sealed at both ends, and the transmission means 44 is a length of flexible pipe that joins the storage volume 42 to the dispensing container 40.
The use of the apparatus 300 in making the layer of cured or partially-cured material 50 will now be described with reference to Figures 4 to 8.
The process of making the layer may take place on site shortly before the layer of material is applied to the leading edge of a wind turbine blade, or the process may take place offsite at a separate facility, such that the flexible membrane 326 is provided to the site with the layer of material pre-applied.
First, the flexible membrane 326 is arranged in the application configuration as shown in Figure 4. To this end, the membrane 326 is allowed to rest on the flat support surface 329a of the first support structure 325a of the substrate support 325.
Next, as shown in Figure 5, a layer of curable liquid material, in this case liquid paint 50, is applied to the flat portion of the flexible membrane 326 using the applicator 324. The liquid paint is passed from the storage volume 42 to the dispensing container 40 via the transmission means 44. Once in the dispensing container 40, liquid paint is dispensed onto the flexible membrane 326 from the slot 46. The applicator 324 is dragged along the length of the flexible membrane 326 to apply the layer of paint along the entire length or just part of the length of the flexible membrane 326.
The resulting layer of paint 50 is shown in Figure 6. The footprint of the layer is an elongate strip that extends along a longitudinal axis L. The layer is of a uniform and predetermined thickness that is controlled by the size and shape of the slot 46. The layer of paint may be of any suitable predetermined thickness, and is typically between 0.5 mm and 1 mm thick, though layers are also envisaged that are 5 mm or more in thickness.
After application, the liquid paint 50 is allowed to gel or partially cure. In particular the liquid paint is allowed to gel until it has a sufficiently high viscosity that it will not flow under the action of gravity. This may take less than 5 minutes, and may, for example require a period of 1 minute. At this stage, the membrane 326 can be moved without disturbing the layer of liquid material.
Once the layer of liquid paint has gelled sufficiently, the membrane 326 is reconfigured into a curing configuration, shown in Figure 7. In the curing configuration, the part of the membrane 326 that supports the layer of liquid paint 50 is arranged in a substantially concave configuration.
Reconfiguration of the membrane 326 into the curing configuration is achieved by causing the membrane 326 to fold partially in a direction perpendicular to the longitudinal axis L so as to cause the membrane 326 to adopt a curved configuration in the vicinity of the liquid layer 50. To this end, the membrane 326 is transferred to the second substrate support 325b and is allowed to rest on the upper support surface 329b with the layer of liquid material 50 overlying the gutter-shaped formation 331, so that it adopts the curved configuration.
After the membrane 326 has been reconfigured into the curing configuration the liquid paint is allowed to cure to form a layer or film of solid paint 50. To effect curing, it may be sufficient to allow the paint to rest for a period of time under atmospheric conditions. For example, the paint may be allowed to cure under atmospheric conditions for a period of 5 minutes to several hours. Alternatively, the layer may be heated to an elevated temperature to expedite the curing process. For example, the layer may be heated to temperatures between 30 °C and 100 °C, or even higher if required, and may be held at that temperature for a time period of 5 minutes to several hours. To this end, a heating means (not shown) may be incorporated into the second substrate support 325b to heat the flexible membrane 326.
After the curing stage, the resulting film of solid paint 50, shown in Figures 8a and 8b, may be fully cured, or it may be partially cured.
By curing the paint in the concave curing configuration, the paint is pre-cured into its solid form with a concave shape as shown in Figure 8a.
Said another way, if the membrane 326, and hence the resulting film 50, were arranged in a flat configuration as shown in Figure 8b, an inherent stress would be present in the film 50. That stress would differ between the upper and lower surfaces 50a, 50b of the film 50. In particular, in the substrate-facing surface 50a (the lower surface of Figure 8) the stress would be compressive, whereas in the outward-facing surface 50b (the upper surface of Figure 8) the stress would be tensile.
Turning now to the apparatus for applying the layer of material to the leading edge of the wind turbine blade, Figure 9 illustrates the membrane 326 and layer of material 50 of Figure 8b being used in conjunction with the third substrate support structure 325c to apply the layer of material 50 to a leading edge 10 of a wind turbine blade 12. In the context of this invention, the leading edge is the edge region to which the layer of material will be applied, and includes the actual leading edge as well as the area on the suction surface and the pressure surface which surround the leading edge, to which the layer of material will be applied.
The third substrate support 325c and flexible membrane 326 are configured such that, upon movement of the leading edge 10 and the flexible membrane 326 towards one another, the flexible membrane 326 will first adopt a presentation configuration, shown in Figure 10a, in which the layer of material 50 is offered up to the leading edge 10 of the wind turbine blade 12 to define an initial area of contact between the layer of material 50 and the leading edge 10, and upon continued movement of the leading edge 10 and the flexible membrane 326 towards one another, the flexible membrane 326 will then be reconfigured by increasing the area of contact between the layer of material 50 and the leading edge 10 until the flexible membrane 326 is in a transfer configuration, shown in Figure 10b, in which the flexible membrane 326 adopts the contours of at least a portion of the leading edge 10, and in which the third substrate support 325c applies a resistive force to push the flexible membrane 326, and hence the layer of material 50, against the leading edge 10.
Turning to Figure 10a, which shows the third substrate support 325c and membrane 326 in more detail, the third substrate support 325c comprises a support frame 330 that defines an internal volume 332. The flexible membrane 326 is positioned in the frame 330 so that it is supported inside the internal volume 332 in a ‘U’-shape. In this example the flexible membrane 326 is positioned in the frame 330 but it is not fixed or secured to the frame. The flexible membrane 326 may hang over the edges of the frame so that the U-shape is formed. In this way, the flexible membrane 326 is able to move over the edges of the frame 330 as the membrane is manipulated.
A substrate reinforcement in the form of a flexible reinforcing membrane 342 is positioned beneath the flexible membrane 326. In this example, the flexible reinforcing membrane 342 is positioned in the frame 330 but it is not fixed or secured to the frame. The flexible reinforcing membrane 342 may hang over the edges of the frame in the same manner as the flexible membrane 326 that defines the substrate support, so that the flexible reinforcing membrane 342 also defines a U-shape.
Beneath the membranes 326, 342, the internal volume 332 also houses a resistive element 334 in the form of an elastically deformable member, which is configured to apply a resistive force that, in use, pushes the membrane 326 against the leading edge of the blade.
A region of free space 338 is defined by the third substrate support 325c beneath the resistive element 334. In the embodiment shown, the free space 338 is created by means of element supports 336 that support the resistive element 334 at its left and right sides. The elements supports 336 are support blocks that extend along the length of the support frame 330 in a direction parallel to the leading edge 10. The element supports 336 hold the resistive element above a base 340 of the third substrate support 325c to define the free space 338 below the resistive element 334 and between the element supports 336.
The reinforcement membrane 342 is provided in the form of a further flexible membrane and may be made of a soft, flexible material, such as a silicon rubber or a suitable plastics material such as polyurethane, polyethylene, polypropylene or nylon. The reinforcement membrane 342 is thicker than the flexible membrane 326 that defines the substrate: for example, the reinforcement membrane 342 may be twice as thick as the flexible membrane 326 that defines the substrate.
Considering now the resistive element 334 in more detail, the resistive element 334 is located in the internal volume 332 of the support frame 330 and is arranged on the side of the flexible membrane 326 that is opposite to the layer-supporting surface 327. In the orientation shown in Figure 10a the resistive element 334 is therefore arranged beneath the flexible membrane 326.
The resistive element 334 is elastically deformable. In the context of this invention “elastically deformable” means that the shape of the resistive element 334 can be changed upon application of a force and/or that the resistive element 334 can be compressed upon application of a force.
To this end, the resistive element 334 is made of an elastically deformable material. For example, the resistive element 334 may be made of a rubber foam such as a polyether foam, or any other suitable deformable material. In the embodiment illustrated, the resistive element 334 takes the form of a layer of rubber foam material, though any suitable configuration of material may be used.
Referring now to Figure 10b, if a downward force F1 is applied generally at the centre of the resistive element 334, the resistive element 334 will be subjected to a three-point bend, with the downward force F1 applied at the centre and opposing upward forces F2 applied by the element supports 336 at the left and right sides of the resistive element 334. This three-point bend causes the resistive element 334 to be elastically deformed into the free space 338 to define a ‘U’-shape and to be elastically compressed.
The arrangement of the third substrate support 325c and flexible membrane 326 allows the flexible membrane 326 to be moved between the presentation and transfer configurations in response to a force being exerted on the membrane 326 by the leading edge of a wind turbine blade. The presence of the free space 338 allows for particularly easy deformation of the resistive element 334 and hence allows for particularly easy reconfiguration of the flexible membrane 326.
In particular, Figure 10a illustrates the third substrate support 325c and the membrane 326 when substantially no force is applied to the membrane 326. In this state, the membrane 326 is in a generally slack or upwards configuration that corresponds to the presentation configuration. Figure 10b illustrates the third substrate support 325c the membrane 326 has been deformed downwards by the downward force F1, with the membrane 326 in a downwards configuration that corresponds to a transfer configuration. In this configuration the resistive element 334 has been elastically deformed into a ‘IT shape such that it extends into the free space 338.
Thus, a downward force exerted on the flexible membrane 326 causes the flexible membrane 326 to adopt the transfer configuration of Figure 10b, and causes the resistive element 334 to be elastically deformed.
The use of the apparatus 320 in applying the layer of material 50 to the leading edge 10 of the wind turbine blade 12 will now be described with reference to Figures 11 to 15.
As shown in Figure 11, before the layer of paint 50 is applied to the leading edge 10, the solid film is laid flat and a layer of adhesive is applied to the upper surface 50b surface of the solid film 50. In this example, the adhesive is a layer of liquid paint 51. Transferring the film 50 from a concave shape to a flat shape for this application does not damage the film because the layer is able to deform elastically. The layer of liquid paint 51 may be applied using the applicator 324 or it may be applied using other means. In the example shown, the layer of liquid paint 51 is the same material as the liquid paint that was used to form the solid layer 50. It is dispensed so as to have a thickness that is sufficient to allow the solid film of paint 50 to bond effectively to the blade.
As shown in Figure 12, once the layer of liquid paint 51 (or other suitable adhesive) has been applied to the flexible membrane 326, the membrane 326 is transferred to the third substrate support 325c and arranged in place above the reinforcement membrane 342. With the flexible membrane 326 in place, the membrane 326 is now ready to be applied to the leading edge 10 of a blade 12.
To apply the solid film of paint 50 to the leading edge 10, the membrane 326 is first arranged below the blade 12. The layer of material 50 is then offered up to the leading edge 10 of the wind turbine blade 12.
To offer up the layer of material 50 to the leading edge 10, the leading edge 10 and the membrane 326 are moved relatively towards one another. In this example, the third substrate support 325c, and hence the membrane 326, are moved upwardly toward the blade. This may be achieved by means of an actuator (not shown), which may be controlled by a control system. Alternatively, the blade 12 can be moved towards the third substrate support 325c to effect the relative movement.
The relative movement continues until the layer of material 50 comes into contact with the leading edge 10 of the blade 12 as shown in Figure 13, at which point the membrane 326 is in the presentation configuration.
Initial contact occurs between the convex tip of the leading edge 10 and the layer of material 50 at a lowermost point of the concave membrane 326. In this way, the initial area of contact between the layer of material 50 and the leading edge 10 is relatively small, in this case being defined by a line of contact that runs along the tip of the leading edge 10.
The flexibility of the membrane 326 means that the layer of material 50 and the leading edge 10 can be brought into contact with one another very gently. This very gentle initial contact over a relatively small initial area means that the solid film 50 is not disturbed as contact is made, which avoids displacement or wrinkling of the film. The gentle contact also ensures that there is very little displacement of the liquid adhesive layer 51 as contact is made, so that the adhesive layer remains at, or close to, a constant predetermined thickness in the central part of the layer, and the solid layer is applied evenly to the leading edge.
After initial contact has been made, relative movement continues and the leading edge 10 of the blade 12 is pushed gradually further against the flexible membrane 326.
As the leading edge 10 is pushed further into the flexible membrane 326, the membrane 326 gradually wraps around the leading edge 10 so that the area of contact between the layer of material 50 and the leading edge 10 gradually increases, with the area of contact growing outwardly towards edges of the flexible membrane 326. The flexible membrane 326 therefore gradually wraps around the leading edge 10, adopting the contours of the leading edge 10 as it does so until the curvature of the membrane 326 matches the curvature of the leading edge 10.
Once the flexible membrane 326 has been sufficiently wrapped around the leading edge 10, the entirety of the layer of material 50 is in contact with the leading edge 10 and has adopted the contours of the leading edge 10. The flexible membrane 326 is then in the transfer configuration, which is shown in Figure 14.
Gradually increasing the area of contact so as to grow the area towards the edges of the membrane means that the contact can remain consistently gentle. This gentle contact guards against disturbance of the solid layer to avoid displacement, breakage and wrinkling of the layer. The gentle contact also guards against displacement of the liquid adhesive layer as the area of contact increases to ensure an even adhesive layer and hence even application of the solid layer of material.
Growing the area of contact outwardly also tends to cause air to be effectively expelled towards the edges of the membrane as the area of contact grows, which guards against air becoming trapped between the layer of material 50 and the leading edge 10 of the wind turbine blade 12.
Thus, the flexible membrane 326 and hence the layer of material 50 are wrapped around the leading edge 10 of the wind turbine blade 12, so that the layer of material 50 is forced to adopt the contours of the leading edge 10 of the wind turbine blade 12. The layer of material 50 on the flexible membrane 326 also adopts the contours of the leading edge 10.
As the area of contact reaches the edges of the layer of material 50, some of the liquid adhesive material 51 that sits between the solid layer 50 and the leading edge 10 in the edge region is displaced slightly outwardly (i.e. toward the trailing edge of the blade), beyond the edge of the solid layer 50. The flexible membrane 326 tends to smooth this adhesive out as it is wrapped around the leading edge 10 to give a layer thickness that tapers to zero in the edge region, as can be seen in the partial close-up inset into Figure 14.
In this way, the wrapping motion provides a layer that is of substantially uniform thickness throughout the bulk of the layer, but provides a small edge region in which the thickness of the layer tapers to zero. As a result, there is no step at the edge of the paint layer 50, unlike in conventional painting in which there is a step at the edge of the paint, and no need to finish the application by hand to remove any excess materials.
The absence of the step at the edge of the paint layer gives the blade an improved aerodynamic performance during use.
In addition to providing this automatic reconfiguration of the membrane 326 into the transfer configuration, the third substrate support 325c and membrane 326 are also configured such that the resistive element 334 causes the membrane 326 to exert a force on the leading edge 10 as the membrane 326 and leading edge 10 are displaced towards one another.
As the leading edge 10 and the flexible membrane 326 are moved towards one another, the leading edge 10 pushes the flexible membrane 326 into the resistive element 334, with the reinforcement membrane 342 sandwiched between the flexible membrane 326 and the resistive element, so as to exert a downward force at the centre of the resistive element 334.
This downward force causes the three-point bend described above that elastically deforms the resistive element 334 into the free space 338, causing the resistive element 334 to adopt a ‘IT shape, and to be elastically compressed.
As a result of the elastic deformation of the resistive element 334, elastic restoring forces tend to counter the deformation and exert a resistive force upwards towards the leading edge 10 as indicated by the arrows in Figure 14. In this way, the resistive element 334 pushes the flexible membrane 326, and hence the layer of material 50 against the leading edge 10.
In this transfer configuration, upward forces are exerted on the leading edge 10. The elastic restoring force caused by deformation of the resistive element 334 tend to push the membrane 326 upwards as has been described. This force causes the membrane 326 to push the layer of material 50 gently onto the leading edge 10. This pushing action ensures that the layer of material is wrapped closely around the leading edge 10 so as to conform exactly to the contours of the leading edge, and also facilitates transfer from the membrane 326 to the leading edge 10.
The reinforcement membrane 342 acts to spread the upward force exerted by the resistive element 334 evenly across the flexible membrane 326. The reinforcement membrane 342 thereby counters any unevenness in the foam layer of the resistive element 334 to ensure an even distribution of force across the flexible membrane 326, and hence across the layer of material 50. In other words, the reinforcement membrane 342 prevents any imperfections (such as wrinkles) in the foam layer 334 from being transferred to the flexible membrane 326, and hence across the layer of material 50.
Once the flexible membrane 326 has been arranged in the transfer configuration, the layer of material 50 is transferred to the leading edge 10 of the wind turbine blade 12.
As noted above, in this example the flexible membrane 326 and the reinforcement membrane 342 are not secured to the frame 330. This means that these membranes do not experience any strain (in the form of stretching) when the leading edge 10 is pushed into the membranes. Avoiding stretching in this way helps to avoid wrinkles in the layer of material and hence to maintain the smoothness of the layer 50.
Because the surface of the flexible membrane 326 is a non-stick surface, the layer of material 50 tends to bond more strongly to the surface of the leading edge 10 of the blade 12, and is thereby transferred from the flexible membrane 326 to the leading edge 10. A release coating may be used to further facilitate transfer from the membrane 326 to the leading edge 10. The smoothness of the membrane 326 also provides for a particularly smooth finish on the external surface of the layer of material 50 that is applied to the leading edge 10, which improves aerodynamic performance of the blade 12.
At this stage, the layer of material 50 is allowed to cure. This may involve simply waiting for a period of time for the material to cure at room temperature. It may also involve heating the layer of material to facilitate curing. To this end, a heating means (not shown) may be incorporated into the third substrate support 325c to heat the flexible membrane 326.
Once a sufficient time period has elapsed the flexible membrane 326 is moved gently away from the leading edge 10 of the blade 12. As the flexible membrane 326 is moved away, the layer of material 50 remains in contact with the leading edge 10, as shown in Figure 15. The layer of material 50 is of substantially uniform and pre-determined thickness, except at the edge regions in which the thickness tapers to zero. The layer of material 50 also has substantially no voids between the material 50 and the leading edge 10, and is effectively bonded to the leading edge 10 of the wind turbine blade 12.
The apparatus can then be used to apply further layers of material to the leading edge of the same blade or to the leading edge of different blades.
As shown in Figure 16, when the film of paint 50 is applied to the convex surface of the leading edge 10, it is forced to adopt a concave shape, similar to the shape that it adopted in the curing configuration of Figure 7.
The upper surface 50b that defined the outward-facing surface as the film 50 was made now lies against the convex surface of the leading edge 12, and the lower surface 50a that defined the substrate-facing surface as the film was made will face away from the surface of the leading edge 10.
When the film of solid paint 50 is forced to adopt this concave configuration, the film returns to a curved configuration that is similar to or close to the curved configuration that it adopted during curing.
In this curved configuration, the outer surface 50a of the film of solid paint 50 that faces away from the blade 10 has a larger radius of curvature than the inner surface of the film that lies against the blade. Thus, the film has different degrees of curvature in the upper and lower surfaces.
If the film had not been cured into the curved configuration, but had instead been cured flat, the different degrees of curvature at the upper and lower surfaces would result in induced strain and stress in the film that would be of different degrees in the upper and lower surfaces 50a, 50b. If the film were under sufficient strain this may decrease the erosion performance of the film, because the film will not absorb precipitation impact as effectively as a film which is not under strain.
However, by curing the paint into a concave shape rather than allowing the paint to cure while laid flat, the paint undergoes curing in a configuration that is closer to the concave shape that it will eventually adopt when applied to the convex surface of the leading edge. When the layer is applied to the leading edge in its concave configuration, its shape does not differ significantly from its cured shape and there is therefore substantially no stress or strain present in the film. In particular, the layer 50 has a sufficiently low strain that its erosion performance is substantially unaffected. Thus, when the layer 50 is on the leading edge 10, the net stress in the film is reduced compared to the net stress that would have been present in a film that had been cured in a flat configuration.
Curing the paint into a concave shape therefore reduces strain and stress in the applied film, which avoids the degradation of the erosion performance.
This concave pre-curing is particularly beneficial at higher thicknesses of the layer of material, since the strain differential between the upper and lower surfaces increases with the film thickness. For example, in the absence of this curved curing process, for a leading edge having a 10 mm radius of curvature, a film of 0.2 mm thickness would give a strain of approximately 2% when the flat polymer film is stretched around the leading edge, while a film of 1 mm thickness would experience a greater strain of approximately 10%.
In the embodiment described above, the same flexible substrate is used to make the layer of material and to apply the layer of material to the leading edge. However, embodiments are envisaged in which the layer of material is made on a first substrate part and then transferred to a second substrate part for application to the leading edge of the blade. To this end, as shown in Figure 17, the flexible substrate may comprise first and second flexible substrate parts 326a, 326b, the first flexible substrate part being reconfigurable into the application and curing configurations and the second flexible substrate part being reconfigurable into the presentation and transfer configurations.
Although in the embodiment described the substrate support comprises first, second and third support structures, other suitable configurations of the substrate support are envisaged that allow the membrane to be supported in the application, curing, presentation and transfer configurations. For example, the substrate support may comprise a single support structure configured to support the membrane in all configurations. To this end, the single support structure may comprise both flat and curved surfaces. Other embodiments are envisaged in which a first support structure is configured to support the membrane in the application and curing configurations and a second support structure is configured to support the membrane in the presentation and transfer configurations.
It is also envisaged that to support the membrane in the curing configuration, the membrane may be suspended such that gravity allows the membrane to adopt a Ushaped configuration, in which case the curved surface of the substrate support may be omitted.
Although in the embodiments described the flexible membrane 326 and reinforcement membrane 342 are positioned in the support frame such that the membranes 326, 342 adopt a concave configuration when in the presentation configuration, this need not be the case. For example, embodiments are envisaged in which the flexible membrane 326 and/or the reinforcement membrane 342 are laid flat on the resistive element 334. In this case the flexible membrane 326 may be in a flat configuration when it is presented to the leading edge 10, such that the presentation configuration is a substantially flat configuration. In another example, the resistive element 334 may have a concave shape such that the flexible membrane 326 carrying the curved film 50 can lie in a concave shape for presentation to the leading edge.
Embodiments are also envisaged in which the flexible membrane 326 is arranged in a convex configuration during curing of the layer, such that, during curing, the surface of the layer 50 supported by the membrane would be concave, and the surface of the layer facing outwardly, away from the membrane would be convex. In these embodiments, the layer of material 50 would be removed from the membrane after curing, inverted, and reapplied to the same, or a different, membrane in its inverted form, with the surface that had been concave during curing facing outwardly, away from the membrane, for presentation to the leading edge. In this way, although the layer would be cured in a convex shape, the layer would be applied to the leading edge such that the surface that had been concave during the curing process would lie against the leading edge of the wind turbine blade, thereby resulting in substantially no stress in the layer of material when applied to the leading edge.
The reinforcement membrane 342 is an optional feature and may be omitted from the third substrate support 325c. For example, the upward force exerted by the resistive element 334 and the flexible membrane 326 alone may be sufficiently high and sufficiently even that the reinforcement membrane 342 is not required.
The resistive element 334 need not take the form of a layer of material but may take any suitable form. For example, the resistive element may comprise multiple layers of material, or may comprise a block of material. Embodiments are also envisaged in which the element supports are omitted and there is no free space provided beneath the resistive element 334, but in which the resistive element is sufficiently large and sufficiently easily deformable that it can deform to accommodate the leading edge of the blade without the need for free space.
Although in the embodiment described the layer of liquid material is applied using an applicator of the sort shown in Figures 2 and 3, the layer of liquid material could be applied by other means, for example by pouring the liquid material onto the surface or using a device such as a brush or spatula.
The flexible membrane 326 and the reinforcement membrane 342 could in an example be secured to the frame 330. In this case, when the leading edge 10 is pushed onto the flexible membrane 326, the flexible membrane will experience some strain as it is stretched and becomes taut. However, as the geometry of the leading edge 10 changes along the length of the wind turbine blade a taut membrane may introduce wrinkles into the film 50. Therefore, it is preferred for the membranes to be unsecured to the frame 330.
Although the invention is particularly effective in applying uniform layers of material to a leading edge of a wind turbine blade, it is also envisaged that the invention may be used to apply layers of non-uniform thickness. For example, the slot in the dispensing container may be shaped to as to provide a layer of varying thickness.
In the embodiment described, the membrane is flat across its entire surface, however, this need not be the case. For example, the membrane may be provided with ridge formations to hold the liquid material in a particular place during curing.
The method and apparatus described can be used to apply a layer of material to the leading edge of the wind turbine blade during manufacture of the blade, or they can be used to apply a layer of material to the leading edge of the wind turbine blade in-situ when it is installed on wind turbine or on the ground. Although in the example described above the apparatus is used in a horizontal orientation, the apparatus may be used in any suitable orientation to apply the layer to the leading edge: for, example, the apparatus may be used in a vertical orientation, particularly if used to apply a layer of material to a leading edge while the blade is in-situ.
The present invention is therefore not limited to the exemplary embodiments described above and many other variations or modifications will be apparent to the skilled person without departing from the scope of the present invention as defined in the following claims.

Claims (40)

Claims
1. A method of making a layer of cured material for application to a leading edge of a wind turbine blade, the method comprising:
arranging a flexible substrate in an application configuration in which a layersupporting surface of the flexible substrate is substantially flat;
applying a layer of liquid material to the layer-supporting surface;
reconfiguring the flexible substrate into a curing configuration in which a part of the layer-supporting surface that supports the layer of material is curved; and curing the layer of material with the flexible substrate in the curing configuration to form a curved layer of cured material on the flexible substrate.
2. The method of Claim 1, wherein the step of arranging the flexible substrate in the application configuration comprises arranging at least a part of the flexible substrate on a flat surface.
3. The method of Claim 1 or Claim 2, wherein the step of arranging the flexible substrate in the curing configuration comprises arranging at least a part of the flexible substrate on a curved surface.
4. The method of any preceding claim, wherein the step of reconfiguring the flexible substrate comprises moving the flexible substrate from a first support structure configured to support the flexible substrate in the application configuration to a second support structure configured to support the flexible substrate in the curing configuration.
5. The method of any preceding claim, wherein the layer of liquid material applied to the layer-supporting surface defines a footprint that is elongate along a longitudinal axis, and the step of reconfiguring the flexible substrate into the curing configuration comprises causing at least a part of the flexible substrate to fold about the longitudinal axis.
6. The method of any preceding claim, wherein the step of applying a layer of liquid material to the layer-supporting surface comprises applying a liquid layer of substantially uniform thickness to the layer-supporting surface.
7. The method of Claim 6, wherein the step of applying a liquid layer of substantially uniform thickness comprises:
providing a liquid container comprising dispensing slot of substantially uniform height;
allowing liquid to flow from the liquid container onto the layer-supporting surface via the dispensing slot.
8. The method of any preceding claim, comprising applying a layer of liquid material having a thickness less than approximately 5 mm.
9. The method of any preceding claim, comprising allowing the layer of liquid material to cure partially to increase the viscosity of the liquid layer before reconfiguring the flexible substrate into the curing configuration.
10. The method of any preceding claim, comprising heating the layer of material while the flexible substrate is in the curing configuration to cure the layer of liquid material.
11. The method of any preceding claim wherein the liquid material comprises a curable liquid paint or resin.
12. A method of applying a layer of material to a leading edge of a wind turbine blade, the method comprising:
making a layer of cured material according the method of any of Claims 1 to 10; and applying the layer of cured material to the leading edge.
13. The method of Claim 12, wherein the step of applying the layer of cured material to the leading edge of the wind turbine blade comprises:
wrapping a flexible substrate supporting the layer of cured material around the leading edge; and transferring the layer of material from the flexible substrate to the leading edge of the wind turbine blade.
14. The method of Claim 13, wherein the step of wrapping the flexible substrate around the leading edge comprises:
arranging the flexible substrate in relation to the leading edge of the wind turbine blade with the flexible substrate in a presentation configuration such that an initial area of contact is defined between the layer of material and the leading edge; and reconfiguring the flexible substrate into a transfer configuration in which the flexible substrate adopts to the contours of the leading edge by increasing the area of contact between the layer of material and the leading edge.
15. The method of any of Claims 12 to 14, comprising applying an adhesive layer to the layer of cured material before applying the layer of cured material to the leading edge of a wind turbine blade.
16. The method of Claim 15, wherein the adhesive layer is a layer of liquid adhesive, and wherein the layer of cured material and the layer of liquid adhesive are layers of substantially the same material in cured and liquid states respectively.
17. The method of any of Claims 12 to 16, wherein the layer of material is applied to the blade in-situ on a wind turbine.
18. Apparatus for making a cured layer of material for application to a leading edge of a wind turbine blade, the apparatus comprising:
a flexible substrate that is reconfigurable between an application configuration in which a layer-supporting surface of the flexible substrate is substantially flat and a curing configuration in which the layer-supporting surface is substantially curved; and a substrate support configured to support the flexible substrate in the application configuration and the curing configuration.
19. The apparatus of Claim 18, wherein the substrate support comprises a flat surface for supporting the flexible substrate in the application configuration.
20. The apparatus of Claim 18 or Claim 19, wherein the substrate support comprises a curved surface for supporting the flexible substrate in the application configuration.
21. The apparatus of Claim 20, wherein the curved surface is concave.
22. The apparatus of Claim 21, wherein the curved surface is defined by a substantially gutter-shaped formation on the substrate support.
23. The apparatus of any of Claims 18 to 22, wherein the substrate support comprises a first support structure configured to support the flexible substrate in the application configuration and a second support structure configured to support the flexible substrate in the curing configuration.
24. The apparatus of any preceding claim, wherein the flexible substrate comprises a flexible membrane.
25. The apparatus of any of Claims 18 to 24, wherein the flexible substrate has thickness that is less than approximately 2 mm.
26. The apparatus of any of Claims 18 to 25, wherein the flexible substrate is made of a material selected from the group of: silicon rubber, polyurethane, polyethylene, polypropylene or nylon.
27. The apparatus of any of Claims 18 to 26, wherein the apparatus comprises an applicator for applying a layer of material to the flexible substrate.
28. The apparatus of Claim 27, wherein the applicator comprises a container provided with slot for dispensing the material onto the flexible substrate.
29. Apparatus for applying a layer of material to a leading edge of a wind turbine blade, the apparatus comprising the apparatus of any of Claims 18 to 28, wherein:
the flexible substrate is further reconfigurable into a presentation configuration in which, in use, a layer of material supported by the flexible substrate can be offered up to the leading edge of the wind turbine blade to define an initial area of contact between the layer of material and the leading edge, and a transfer configuration in which the flexible substrate adopts the contours of at least a portion of the leading edge; and the substrate support is further configured to support the flexible substrate in the presentation and transfer configurations such that the flexible substrate can be reconfigured from the presentation configuration into the transfer configuration by increasing the area of contact between the layer of material and the leading edge upon relative movement of the flexible substrate and the leading edge towards one another.
30. The apparatus of Claim 29, wherein the substrate support comprises a resistive element that is configured to apply a resistive force to push the flexible substrate against the leading edge as the flexible substrate and the leading edge are moved towards one another.
31. The apparatus of Claim 29 or Claim 30, wherein the flexible substrate comprises first and second flexible substrate parts, the first flexible substrate part being reconfigurable into the application and curing configurations and the second flexible substrate part being reconfigurable into the presentation and transfer configurations.
32. The apparatus of any of Claims 29 to 30, wherein the substrate support comprises a first substrate support structure configured to support the flexible substrate in the application and curing configurations and a second substrate support structure configured to support the flexible substrate in the presentation and transfer configurations.
33. Apparatus for applying a layer of material to a leading edge of a wind turbine blade, the apparatus comprising:
a flexible substrate; and a layer of cured or semi-cured material for application to a leading edge of a windturbine blade, the layer being supported by the flexible substrate and having a substratefacing surface and an outward-facing surface;
wherein the flexible substrate is configurable into an application configuration in which the substrate adopts the contours of the leading edge of a wind turbine blade; and wherein the layer of material is configured such that, if the flexible substrate is arranged in a flat configuration, an inherent stress in the outward-facing surface of the layer is tensile and an inherent stress in the substrate-facing surface of the layer is compressive.
34. The apparatus of Claim 33, wherein the flexible substrate comprises a flexible membrane.
35. The apparatus of Claim 33 or Claim 34, wherein the flexible substrate has thickness that is less than approximately 2 mm.
36. The apparatus of any of Claims 33 to 35, wherein the flexible substrate is made of a material selected from the group of: silicon rubber, polyurethane, polyethylene, polypropylene or nylon.
37. The apparatus of any of Claims 33 to 36, wherein the layer of material comprises a layer of cured or semi-cured paint.
38. The apparatus of Claim 37, wherein the paint is an erosion-resistant paint.
39. The apparatus of any of Claims 33 to 38, wherein the layer of material has a thickness less than 5 mm.
40. The apparatus of any of Claims 33 to 38, wherein the layer of material has a thickness less than 2 mm.
Intellectual
Property
Office
Application No: GB1613855.4 Examiner: Mr Robin Jones
GB1613855.4A 2015-12-15 2016-08-12 Method and apparatus for making a layer of material to be applied a leading edge of a wind turbine blade Withdrawn GB2552835A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
GB1613855.4A GB2552835A (en) 2016-08-12 2016-08-12 Method and apparatus for making a layer of material to be applied a leading edge of a wind turbine blade
EP16819811.7A EP3389990B1 (en) 2015-12-15 2016-12-14 Method and apparatus for making a layer of material to be applied to a leading edge of a wind turbine blade
PCT/DK2016/050432 WO2017101948A1 (en) 2015-12-15 2016-12-14 Method and apparatus for making a layer of material to be applied to a leading edge of a wind turbine blade

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1613855.4A GB2552835A (en) 2016-08-12 2016-08-12 Method and apparatus for making a layer of material to be applied a leading edge of a wind turbine blade

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GB201613855D0 GB201613855D0 (en) 2016-09-28
GB2552835A true GB2552835A (en) 2018-02-14

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03279902A (en) * 1990-03-29 1991-12-11 Toshiba Corp Reflecting mirror and production thereof
WO2007075497A2 (en) * 2005-12-14 2007-07-05 Hontek Corporation Method and coating for protecting and repairing an airfoil surface
US20090181586A1 (en) * 2008-01-10 2009-07-16 Wagner Jr Richard William Surfboard and method and apparatus of manufacture
US20090295015A1 (en) * 2008-05-28 2009-12-03 Kuntz Michael P Flexible tooling method and apparatus
WO2012029515A1 (en) * 2010-09-03 2012-03-08 東レエンジニアリング株式会社 Web coating device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03279902A (en) * 1990-03-29 1991-12-11 Toshiba Corp Reflecting mirror and production thereof
WO2007075497A2 (en) * 2005-12-14 2007-07-05 Hontek Corporation Method and coating for protecting and repairing an airfoil surface
US20090181586A1 (en) * 2008-01-10 2009-07-16 Wagner Jr Richard William Surfboard and method and apparatus of manufacture
US20090295015A1 (en) * 2008-05-28 2009-12-03 Kuntz Michael P Flexible tooling method and apparatus
WO2012029515A1 (en) * 2010-09-03 2012-03-08 東レエンジニアリング株式会社 Web coating device

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