Abstract
Provided is an adhesive sheet for mounting a protective shell to a wind turbine blade, wherein the adhesive sheet includes a hot-melt adhesive layer, wherein on at least one surface of the adhesive layer, at least one fixation structure consisting of a pressure-sensitive adhesive is attached.
Claims
1. An adhesive sheet for mounting a protective shell to a wind turbine blade, wherein the adhesive sheet consists of a hot-melt adhesive layer, wherein on at least one surface of the adhesive layer, at least one fixation structure consisting of a pressure-sensitive adhesive is attached.
2. The adhesive sheet according to claim 1, wherein the hot-melt adhesive layer comprises at least one fixation structure on each of two opposing surfaces.
3. The adhesive sheet according to claim 1, wherein the fixation structure comprises a plurality of fixation areas, which are arranged spaced from one another on the surface.
4. The adhesive sheet according to claims 1, wherein the fixation structure comprises a plurality of fixation elements, which are arranged spaced from each other.
5. The adhesive sheet according to claim 4, wherein the fixation elements or at least a part of the fixation elements are arranged along at least one straight line and/or along at least one curve with a sinusoidal shape.
6. The adhesive sheet according to claim 1, wherein the fixation structure is printed on the at least one surface of the hot-melt adhesive layer.
7. A method for mounting a protective shell to a wind turbine blade, comprising the following steps: arranging the adhesive sheet according to claim 1 on a wind turbine blade, wherein the fixation structure is used to fixate the adhesive sheet on the wind turbine blade, arranging a protective shell on the adhesive sheet.
8. The method according to claim 7, wherein an adhesive sheet with at least one fixation structure on each of two opposing surfaces of the hot-melt adhesive layer is used, wherein the protective shell fixated to the adhesive sheet using the fixation structure on the surface of the adhesive layer directed towards the protective shell.
9. The method according to claim 7, wherein a vacuum is applied to the adhesive sheet and the protective shell after their arrangement on the wind turbine blade.
Description
BRIEF DESCRIPTION
[0021] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:
[0022] FIG. 1 shows a first embodiment of an adhesive sheet according to the invention;
[0023] FIG. 2 shows a second embodiment of an adhesive sheet according to the invention;
[0024] FIG. 3 shows a third embodiment of an adhesive sheet according to the invention;
[0025] FIG. 4 shows a fourth embodiment of an adhesive sheet according to the invention;
[0026] FIG. 5 shows a cross-sectional view of an adhesive sheet according to an embodiment of the invention;
[0027] FIG. 6 shows an adhesive sheet according to an embodiment of the invention in a protective shell mounted to a wind turbine blade; and
[0028] FIG. 7 shows a cross section of an adhesive sheet according to an embodiment of the invention in a protective shell mounted on a wind turbine blade.
DETAILED DESCRIPTION
[0029] In FIG. 1, a first embodiment of an adhesive sheet 1 according to embodiments of the invention is shown. The adhesive sheet 1 comprises a hot-melt adhesive layer 2 and a fixation structure 3. In this embodiment, the fixation structure 3 comprises a plurality of square-shaped adhesive areas 4 consisting of a pressure-sensitive adhesive attached on the surface of the hot-melt adhesive layer 2. The fixation areas 4 are arranged spaced from one another on the surface of the hot-melt adhesive layer 2, so that gaps 5 are formed between neighboring fixation areas 4. The gaps 5 facilitate an evacuation of the volume underneath the adhesive sheet 1 when the adhesive sheet 1 is arranged on a wind turbine blade in its mounted state. Besides having a square-shape, the fixation areas 4 can have also rectangular, triangular or a polygonal shape.
[0030] In FIG. 2, a second embodiment of an adhesive sheet 1 according to embodiments of the invention is depicted. The fixation structure 3 comprises a plurality of fixation elements 6 consisting of pressure-sensitive adhesive, which are aligned on the surface of the hot-melt adhesive layer along a center straight line 7 and a plurality of additional straight lines 8. The adhesive sheet 1 comprises a rectangular shape, wherein the center straight line 7 is aligned parallel to the longer edges 9 of the adhesive sheet 1. Also, the center line 7 is aligned within the center or close to the center of the shorter edges 10 of the adhesive sheet 1. The additional straight lines 8 are arranged under an angle to the center straight line 7 or the longer edges 9 of the adhesive sheet 1, respectively. The center straight line 7 can be used for instance to fixate the adhesive sheet to an edge of a wind turbine blade, wherein the additional straight lines 8 are used for attachment of the adhesive sheet to the surfaces of the wind turbine blade adjacent to the edge of the wind turbine blade. It is also possible that more than one center line 7 is provided, which are arranged parallelly in a short distance to a geometrical center of the shorter edges 10 of the rectangular adhesive sheet 1.
[0031] In FIG. 3, a third embodiment of an adhesive sheet 1 according to embodiments of the invention is shown. In this embodiment, the fixation structure 3 comprises a plurality of dot-shaped fixation elements 11, which are arranged along two curves 12 with a sinusoidal shape. Of course, more than two curves 12 with a sinusoidal shape can be provided on one or both surfaces of the hot-melt adhesive layer 2.
[0032] In FIG. 4, a fourth embodiment of an adhesive sheet 1 according to embodiments of the invention is shown. Thereby, the fixation structure 3 comprises fixation elements 6 arranged along two center straight lines 7, a plurality of additional straight lines 8 and a sinusoidal curve 12. Of course, also other combinations and/or arrangements of fixation elements can be provided as well.
[0033] In FIG. 5, a schematical side view of an adhesive sheet 1 according to embodiments of the invention is shown. The adhesive sheet 1 can be fixated with the fixation elements 6, 11 to a surface of the wind turbine blade, so that underneath a portion 17 of the adhesive sheet, which is not covered by the fixation structure 3, air can be removed by applying a vacuum. Both the usage of the fixation elements 6 shown in FIGS. 2 and 4 as well as the dot-shaped fixation elements 11 depicted in FIG. 3 or the fixation areas 4 with the gaps 5 in between shown in FIG. 1 facilitate the creation of a vacuum underneath the adhesive sheet 1. The fixation areas 4 and the fixation elements 6, 11 can be formed by printing the pressure-sensitive adhesive on the hot-melt adhesive layer 2 of the adhesive sheet 1.
[0034] In FIG. 6, a wind turbine blade 13 is shown. In a tip area 14 of the wind turbine blade 13, an adhesive sheet 1 and a protective shell 15 are arranged on a leading edge 16 of the wind turbine blade 13. A method for mounting a protective shell 15 to a wind turbine blade 1 according to embodiments of the invention can be performed for instance during fabrication of the wind turbine blade 13 or during a repair process on a wind turbine blade 13, which is mounted on an already operative wind turbine. In such a method, first the adhesive sheet 1 is arranged on the leading edge 16 of the wind turbine blade 13, wherein the fixation structure 3 of the adhesive sheet 1 is used to fixate the adhesive sheet 1 on the wind turbine blade 13. Afterwards, the protective shell 15 is arranged on the adhesive sheet 1. Afterwards, it is possible that the adhesive sheet 1 is heated for activation of the hot-melt adhesive layer 2. This can be done for instance using a heating blanket covering both the adhesive sheet 1 and the protective shell 15. For improvement of the attachment of the protective shell 15 to the adhesive sheet 1 or the wind turbine blade 13, respectively, a vacuum can be applied for removing the air underneath the protective shell 15 and the adhesive sheet 1. This can be done for instance using a vacuum heating blanket, which is formed to create a vacuum underneath the heating blanket and/or by application of a vacuum bag to the wind turbine blade 13, wherein the vacuum bag covers the protective shell 15, the adhesive sheet and at least a part of the wind turbine blade 13, so that by the evacuation of the vacuum bag, also the air between the adhesive sheet 1 and the protective shell 15 as well as in between the wind turbine blade 13 and the adhesive sheet 1 can be removed.
[0035] When using an adhesive sheet 1 which exhibits fixation structures 3 on each of two opposing surfaces, both the adhesive sheet 1 and the protective shell 15 can be attached prior to the activation of the hot-melt adhesive layer 2 to the surface of the wind turbine blade 13. This facilitates both the arrangement of the adhesive sheet 1 and the protective shell 15 on the wind turbine blade and enables, for instance in the case of misalignment, a removal of the protective shell 15 and/or the adhesive sheet 1 and their reattachment.
[0036] In FIG. 7, a cross-section according to the dashed line VII-VII in FIG. 6 is shown. Besides a cross section of the wind turbine blade 13, also the adhesive sheet 1 and the protective shell 15 are shown in a state mounted to the leading edge 16 of the wind turbine blade 13. Both the adhesive sheet 1 and the protective shell 15 are arranged on the leading edge 16 of the wind turbine blade 13, so that they wrap a circumference of the wind turbine blade 13 at least partially. Due to the large contact area between the adhesive sheet 1 and the wind turbine blade 13 and/or the protective shell 15, respectively, a stable attachment of both the adhesive sheet 1 to the wind turbine blade 13 and the protective shell 15 to the adhesive sheet 1 or the wind turbine blade 13, respectively, is obtained by using the fixation structures consisting of pressure-sensitive adhesive. An attachment of the adhesive sheet 1 to the wind turbine blade 13 can occur for instance by pressing the adhesive sheet 1 to a surface of the wind turbine blade 13 activating the pressure-sensitive adhesive enabling the fixation of the adhesive sheet 1 to the wind turbine blade 13. Also a fixation of the protective shell 15 can occur by pressing the protective shell 15 to the already attached adhesive sheet 1.
[0037] After a curing of the hot-melt adhesive layer 2 by a thermal treatment, a trimming and/or grinding of the surface of the wind turbine blade 13 can occur for flattening the edges of the adhesive sheet 1 or the remainder of the adhesive, respectively, and of the protective shell 15, so that a flat and smooth surface of the wind turbine blade 13 is obtained. This can increase the aerodynamic properties of the wind turbine blade 13. The trimming and/or grinding can be performed for instance manually using respective trimming and/or grinding devices or machines.
[0038] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.
[0039] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.
