Method for producing preform element for blade of wind turbine, preform element, blade of wind turbine and wind turbine

Abstract

Method for manufacturing a preform element (7) for a blade (2) of a wind turbine (1), comprising the steps of: a) arranging a preform element build material (17, 26) comprising a curable adhesive agent on a molding surface (11) of a mold (10) such that the shape of the preform element build material (17, 26) is adapted to the shape of the molding surface (11); b) arranging at least one shaped element (22) on or on the preform element building material (17, 26) such that a shaped surface of the shaped element (22) defines a contact surface of the preform element (7), the shaped surface having a shape corresponding to the contact surface of the blade part, the contact surface is arranged to be in contact with the contact surface of the preformed element (7) in the manufactured blade (2); and c) curing the preform element building material (17, 26) in order to preserve the shape of the preform element (7), which is defined by the molding surface (11) and the shaped element (22).

Description

Technical Field

[0001] The invention relates to a method for manufacturing a preformed element for a blade for a wind turbine. Background Art

[0002] A wind turbine generally comprises a rotor with a plurality of rotor blades, and is basically used for converting wind energy into electrical energy by means of a generator. Due to the huge size of wind turbine blades, their manufacture is a major challenge for the manufacture of wind turbines.

[0003] One technique used to facilitate the manufacture of wind turbine blades is the use of preformed building elements, or respectively preformed elements. A preformed element is a preformed part or portion of a blade, which is used in particular to build a corresponding blade shell. To manufacture the blade, a plurality of preformed elements of the blade and certain other parts are arranged like a beam in a blade half-mold. After the respective parts of the blade are attached to each other by, for example, gluing and / or injecting resin, they usually constitute the outer shell of the blade. Finally, the two blade half-molds are closed in order to build the final blade.

[0004] The preformed element can be manufactured in a mold, which is used to arrange and attach the parts of the preformed element. The preformed element can include multiple layers, in particular fiber mats or sheets and / or core materials. The core material can be a flexible or rigid wooden board, for example a wooden board of balsa wood.

[0005] In many cases, preformed elements can be made separately and independently from each other. However, when they are stacked on top of each other in the blade half-mold, they should fit together as well as possible. In particular, if preformed elements have been made in different molds, there is a risk that the geometric shapes of these preformed elements do not match perfectly. The differences in these respective shapes can cause delamination, wrinkles or points without cured adhesive agents. Therefore, the mechanical strength and durability of the blade can be reduced. If a blade part similar to a beam or a spar cap is sandwiched between two preformed elements in the final blade, the same problem can occur. In this case as well, the shapes of the preformed elements have to fit each other and the shape of the blade part. Summary of the invention

[0006] It is therefore an object of the present invention to provide an improved concept for manufacturing a preformed element for a blade for a wind turbine, in particular with respect to the problems being addressed.

[0007] According to the invention, this problem is solved by a method as initially described, which has the following steps:

[0008] a) arranging a preformed element building material comprising a curable binding agent on a molding surface of a mold such that the shape of the preformed element building material is adapted to the shape of the molding surface,

[0009] b) arranging at least one shaping element on or at the preformed element building material such that a shaping surface of the shaping element defines a contact surface of the preformed element, wherein the shape of the shaping surface corresponds to a contact surface of a blade part, the contact surface of the blade part being arranged to be in contact with the contact surface of the preformed element in the manufactured blade, and

[0010] c) curing the preformed element building material so as to preserve the shape of the preformed element, as defined by the molding surface and the forming element.

[0011] The preformed element building material constitutes or forms a preformed element, which is ultimately used to build the final blade. In the method according to the invention, the preformed element component material is arranged so that it is in contact with the forming element and with the molding surface. The geometry of the components of the surface of the preformed element building material is defined by the molding surface. Typically, the mold and its surface include a rigid structure so that the shape of the preformed element building material adapts to the shape of the mold surface.

[0012] The invention is based on the idea that the contact surface of the preformed element or the corresponding preformed element building material and the corresponding forming surface of the forming element automatically match each other because these surfaces are in contact with each other. Therefore, the contact surface of the preformed element building material and the forming surface of the forming element form negative and complementary surfaces to each other. Therefore, the forming element serves as a shape-forming element for the preformed element building material. Because the shape of the forming surface of the forming element is equal to the shape of the contact surface of the blade part, which will be connected to the preformed building element during the manufacture of the blade, the preformed element and the blade part perfectly match each other in the final blade.

[0013] The shaped element can comprise a rigid structure. The shaped element can be used as a component of a finished blade or a corresponding blade part, or as a "dummy element", i.e. an element constituting a replica of a blade part, which can be used in particular for a plurality of moulding processes of a plurality of preformed elements. The overall geometry of the shaped element can correspond to the geometry of the blade part. However, only a part of the shaped element can constitute the contact surface.

[0014] After the preformed element building material has solidified or hardened, respectively, the preformed element building material constitutes a preform. The preformed element is taken out of the mold and can be separated from the forming element. Because the binding agent has solidified, the contact surface of the preformed element remains stable and the preformed element can be stored or transported to a blade mold for further processing to manufacture the final blade.

[0015] In a preferred embodiment of the present invention, at least one first preformed element building material is arranged on the molding surface, wherein the forming element is or includes at least one second preformed element building material, which is arranged on or at the first preformed element building material. In this embodiment, two preformed elements that are in contact with each other in the final blade are manufactured together and simultaneously, so that their contact surfaces automatically define each other, and therefore fit together in the manufactured blade, and these preformed elements are positioned adjacently at the manufactured blade. Therefore, and in particular in this embodiment, the forming element itself can be a component of the final blade. In this embodiment, the forming element includes a flexible structure so that it does not include a defined shape that is transformed into the preformed element building material, but the shapes of the preformed element building material and the forming element are adapted to each other. Therefore, the forming element is used as a shape-forming element for the preformed element building material, and vice versa.

[0016] The further forming element can be sandwiched between the first preformed element building material and the second preformed element building material. In addition to the forming process of the first and second preformed element building materials as described in the previous paragraph, the contact surface of each of the preformed element building materials that are in contact with the corresponding forming surface of the (preferably rigid) further forming element is adapted to each other. In this embodiment, the shape of the first preformed element formed by the first preformed element building material, the shape of the second preformed element formed by the second preformed element building material and the shape of the further forming element or the respective further blade part match each other.

[0017] The shape of the forming surface of the forming element can correspond to the shape of the contact surface of a blade part, which can be a spar cap or a spar, i.e. a part extending in the longitudinal direction of the final blade and constituting at least a part of the mechanical stability of the blade. The blade part can be a part of a blade root or a core, which is specifically made of wood, such as balsa wood, and / or a polymer material, such as polyethylene terephthalate (PET), and / or a cured polymer foam, which can comprise glass fibers, carbon fibers and / or aramid fibers.

[0018] The forming element can be tapered and arranged laterally on the preformed element building material and between the mould surface and the preformed element building material, wherein the blade part is another preformed element which is arranged to be laterally adjacent to the preformed element in the manufactured blade, wherein the contact surface of the blade part is tapered. Thus, the forming element is placed on the mould surface such that a lateral part of the preformed element building material overlaps the forming element. In the final blade, a corresponding part of the preformed element overlaps another preformed element which is arranged to be adjacent to the preformed element and which comprises a complementary edge.

[0019] Preformed element building material can be arranged between lower vacuum foil and upper vacuum foil, wherein vacuum is produced between mold surface and lower vacuum foil and between lower vacuum foil and upper vacuum foil.In this embodiment, lower vacuum foil is located on mold surface, wherein preformed element building material is arranged on lower vacuum foil.Next, upper vacuum foil is located on the top of preformed element building material.Vacuum foil can be attached to mold accordingly using double-sided tape or butyl band.(that is, between mold surface and lower vacuum foil) and space below upper vacuum foil below lower vacuum foil are airtightly sealed, so as to allow vacuum to be produced below lower vacuum foil and below upper vacuum foil.This causes close fit between mold surface and lower vacuum foil and preformed element building material and vacuum foil, so as to ensure the plane and smooth surface of final preformed element.After evacuating vacuum, vacuum foil can be welded together, so as to form vacuum-tight airbag for preformed element building material.Upper and lower vacuum foils define or limit the space of final preformed element.

[0020] If the one or a first preformed element building material and the one or a second preformed element building material are provided, the first preformed element building material can be arranged between the first lower vacuum foil and the first upper vacuum foil, wherein the second preformed element building material can be arranged between the second lower vacuum foil and the second upper vacuum foil, wherein the vacuum is generated between the mold surface and the first lower vacuum foil, between the first lower vacuum foil and the first upper vacuum foil, between the first upper vacuum foil and the second lower vacuum foil, and between the second vacuum foil and the second upper vacuum foil. All aspects of the lower vacuum foil and the upper vacuum foil that have been described in the previous paragraphs are valid for the first lower vacuum foil and the first upper vacuum foil in this embodiment. For the second lower vacuum foil and the second upper vacuum foil, these aspects are also valid except for the fact that the second lower vacuum is not located on the mold surface but on the first upper vacuum foil. If the one or another forming element is sandwiched between the first preformed element building material and the second preformed element building material, the element can be located between the first upper and second lower vacuum foils.

[0021] In order to ensure that the air between the mold surface and the lower vacuum foil or between the first upper vacuum foil and the second lower vacuum foil is completely removed, in particular in order to avoid local air islands while generating the corresponding vacuum, an air transmission layer can be arranged between the mold surface and the lower vacuum foil and / or between the first upper vacuum foil and the second lower vacuum foil. The air transmission layer can consist of an open, porous material, which allows air to be removed over the complete area between the corresponding surfaces without the formation of air islands. The air transmission layer serves as a "breather layer".

[0022] In order to generate a vacuum between the two respective foils, at least one of the vacuum foils can comprise an outlet, in particular in the form of a valve, which can be connected to a vacuum pump. The outlet is preferably arranged in a side section of the vacuum foil so that it is not covered by other layers of preformed element building material and / or another vacuum foil. The outlet and the area between the two vacuum foils from which the vacuum is evacuated can be connected via an air path element, such as a porous strip or duct, which allows air to be transferred through.

[0023] The preformed element building material can include at least one layer made of fiber sheets and / or rigid core materials, in particular a plurality of stacked layers. The fiber sheets or materials, accordingly, can include glass fibers, carbon fibers and / or aramid fibers. A bonding agent can be applied on the surface of the fiber sheets. The rigid core material can be composed of balsa wood and / or polymer materials (e.g., polyethylene terephthalate (PET)) and / or cured polymer foams, and can provide at least a portion or a major portion of the mechanical stability of the preformed element.

[0024] The adhesive agent can be a heat-fusible powder adhesive. By applying thermal energy or heat to the powder adhesive, it melts or softens or fluidizes accordingly. The adhesive or glue is distributed on the preformed element building material, for example on the layers and in particular on the corresponding fibers. Cooling the adhesive causes the solidification of the molten material, so that the preformed element material (in particular a plurality of layers) adheres and hardens.

[0025] The invention further relates to a preformed element for a blade of a wind turbine, which is produced by a method according to the above description. The advantages and details of the method according to the invention apply correspondingly to the preformed element according to the invention.

[0026] Additionally, the invention relates to a blade for a wind turbine, comprising at least one preformed element according to the invention. The advantages and details of the method and the preformed element according to the invention apply correspondingly to the blade according to the invention.

[0027] Finally, the invention relates to a wind turbine comprising at least one blade according to the invention. The advantages and details of the method, the preformed element and the blade according to the invention are correspondingly applied on a wind turbine according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. However, the drawings are merely schematic diagrams designed for the purpose of illustration only and do not limit the present invention. The drawings illustrate:

[0029] Figure 1 is an embodiment of a wind turbine according to the invention having three blades according to the invention, wherein each blade comprises a plurality of preformed elements according to the invention,

[0030] Figure 2-3 According to two different embodiments Figure 1 A cross-sectional view of one of the blades of a wind turbine, where the cutting line is at Figure 1 Indicated by II–II,

[0031] Figure 4-10 The first embodiment of the method according to the present invention is shown in FIG. Figure 2 Schematic description of the steps of preforming elements of a blade 3.

[0032] Figure 11-13 is a schematic descriptive diagram showing the steps of manufacturing a second embodiment of a preformed element of the present invention according to a second embodiment of a method of the present invention.

[0033] Fig.14 yes Fig.12 Cross-sectional view of a configuration with the cutting line at Fig.12 indicated by XIV–XIV, and

[0034] Fig.15 is a cross-sectional view through a blade half-mold having a plurality of preformed elements which have been formed by means of Figure 11-14 The method described was used to manufacture the DETAILED DESCRIPTION

[0035] exist Figure 1 , an embodiment of a wind turbine 1 according to the invention is illustrated. The wind turbine 1 comprises three blades 2 according to the invention, which are attached to a hub 3 of the wind turbine 1. The hub 3 is mounted on the front side of a nacelle 4, which is supported by a tower 5 and houses a generator 6 for generating electrical energy from the wind-induced rotation of the blades 2 and the hub 3.

[0036] Figure 2 The diagram shows a cross-sectional view of one of the blades 2, wherein the cross-section line is in Figure 1denoted by the lines II–II. The blade 2 comprises a plurality of preformed elements 7, which respectively constitute the blade 2 or its shell. The blade 2 comprises a plurality of sections, wherein in each section two preformed elements 7 are stacked on top of each other. At the section of the blade 2, where the shear web 8 of the blade 2 is located, a spar cap 9 is arranged between two stacked preformed elements 7 or is sandwiched therebetween. When manufacturing the blade 2, the main task is that the shapes of the two preformed elements 7 stacked on top of each other, in particular with the spar cap 9 sandwiched therebetween, fit together as well as possible. In the following, an embodiment of the manufacturing process according to the invention, i.e. the manufacture of a pair of preformed elements 7 with a spar cap 9 in between, will be described with the aid of Figures 3 to 9 describe.

[0037] although Figure 2 The blade 2 of the embodiment is a blade including two shear webs, but Figure 3 A cross-sectional view of another possible embodiment of a blade 2 according to the invention is shown, namely a blade with a single web, such as a blade manufactured using integral blade technology, which is typically used in wind turbines 1 in an offshore environment. In this embodiment, the web 8 is centrally located on a spar or spar cap 9. The blade 2 also consists of one or more blade elements 7, which constitute an inner shell 33 or an outer shell 34 of the blade 2.

[0038] like Figure 4 As shown in FIG. 1 , a mold 10 having a mold surface 11 is provided. The mold surface 11 is swept and an air transport layer 12 (i.e. a "breathable" sheet consisting of a porous material that allows air to pass through) is placed on the mold surface 11. Next, a first lower vacuum foil 13 is arranged on top of the air transport layer 12.

[0039] like Figure 5 In a next step, as illustrated in FIG. 1 , a first lower vacuum foil 13 is sealed, for example by means of a butyl tape 15 or a tape, which is placed at the edge 14 of the mould 10 . Figure 5 Additionally illustrated is an enlarged view on the butyl tape 15 , which serves as a double-sided adhesive tape.

[0040] In order to generate a vacuum between the mold surface 11 and the first lower vacuum foil 13, a vacuum pump (not shown) is connected to a valve-like first outlet 16 of the first lower vacuum foil 13. The air transport layer 12 ensures that air is removed uniformly from the area between the mold surface 11 and the first lower vacuum foil 13, in order in particular to prevent the formation of air islands between these layers. Generating a corresponding vacuum ensures that the foil 13 follows the geometry of the mold surface 11, and thus the final preform element 7 follows the geometry of the mold surface 11.

[0041] Next, refer to Figure 5, the first preformed element building material 17 is located on the first lower vacuum foil 13. Alternatively, a plurality of (in particular stacked) first preformed element building materials 17 can be provided. Figure 5 In the embodiment of the present invention, the first preformed element building material 17 is a fiber sheet 18, which consists of glass fibers, carbon fibers and / or aramid fibers, and which includes a curable binding agent, that is, a heat-fusible powdered binder. Additionally or alternatively, the first preformed element building material 17 can include or consist of a rigid core material, which is made of, for example, balsa wood or a polymer.

[0042] Next, refer to Figure 6 , a first upper vacuum foil 19 is arranged on top of the first preform element building material 17. An air path element 20 is arranged between the first preform element building material 17 and the first upper vacuum foil 19. The "breathable" air path element 20 is composed of a porous material to allow air to pass through, and as Figure 6 The air path element 20 allows air to be transferred from the space between the first lower vacuum foil 13 and the first upper vacuum foil 19 to a valve-like second outlet 21 which is located on the edge 14 of the mould 10 on the first upper vacuum foil 19 .

[0043] Next, the first upper vacuum foil 19 is sealed, for example by means of a butyl tape 15. Next, a vacuum pump is connected to the second outlet 21 in order to generate a vacuum between the first vacuum foils 13, 19. After this, the foils 13, 19 are welded together or sealed in another way in order to form a tight vacuum bag around the first preform element building material 17. Because of the vacuum between the mould surface 11 and the first lower vacuum foil 13 and between the lower vacuum foils 13, 19, the shape of the first preform element building material 17 matches the shape of the mould surface 11.

[0044] Next, refer to Figure 7 , another air transport layer 12 is located on top of the first upper vacuum foil 19. A shaped element 22 is placed on top of this layer 12. The shape of the shaped element 22 corresponds to the shape of the spar cap 9. Alternatively, the shape of the shaped element 22 can correspond to the shape of a part of a spar or a blade root or other part, which is usually located at a corresponding position in the final blade 2. Next, a second lower vacuum foil 23 is located on top of the shaped element 22.

[0045] Figure 8 The diagram shows that Figure 7 Possible alternative to the described steps. In this alternative, the shaping element 22 is surrounded by a core 24, which consists of balsa wood, for example, and which avoids steep transition areas of the pre-shaped element 7. The core 24 also serves as a shaping element for the pre-shaped element 7.

[0046] A valve-like third outlet 25 of the second lower vacuum foil 23 is provided in order to establish a vacuum between the first upper vacuum foil 19 and the second lower vacuum foil 23 in order to ensure that the shape of the second lower vacuum foil 23 matches the shape of the first upper vacuum foil 19, the shaped element 22 and in particular the core 24. After this, the second lower vacuum foil 23 is sealed by means of the butyl tape 15.

[0047] Next, if Fig. 9 As can be seen in FIG. 1 , the second preformed element building material 26 is placed on top of the second lower vacuum foil 23. The second preformed element building material 26 is a core material 27 consisting of balsa wood and fiber sheets 28. Optionally, if the balsa wood core 24 is already arranged between the first upper vacuum foil 19 and the second lower vacuum foil 23 (see FIG. 1 ), the second preformed element building material 26 is placed on top of the second lower vacuum foil 23. Figure 8 ), the core material 27 can be skipped.

[0048] Next, if Fig.10 , a second upper vacuum foil 29 is placed on top of the second preform element building material 26 and is sealed on the edge 14 of the mold 10 by the butyl tape 15. A valve-like fourth outlet 30 is provided between the upper vacuum foils 23, 29 together with a further air path element 20. Air is then evacuated from the space between the vacuum foils 23, 29 in order to ensure that the shape of the second upper vacuum foil 29 matches the shape of the second lower vacuum foil 23 and the second preform element building material 26. The vacuum foils 23, 29 are then sealed in order to form a tight vacuum pocket for the second preform element building material 26.

[0049] After this, the corresponding layers on the packaging mold 10 are completed. The lower vacuum foils 13, 19 constitute a first vacuum bag for the first preform element building material 17, and the upper vacuum foils 23, 29 constitute a second vacuum bag for the second preform element building material 26. In this configuration, the vacuum ensures that the geometric shapes of the preform element building materials 17, 26 match each other and the shape of the forming element 22.

[0050] Next, heat is applied to this arrangement in order to melt the powder binder of the preformed element building material 17, 26. This is preferably done by the forming element 22, which can additionally serve as a heating element with a resistive heating device. Because the preformed element building materials 17, 26 can be of different thicknesses, at the thinner areas of these parts, the thermal insulation element (which can also be a component of the forming element 22) can be used during the stacking of the layers (particularly Figure 6 In particular, less heat is required to activate the curable binder agent in the edges of the preformed element building material 17, 26 than in the central portion of the preformed element building material 17, 26. The heat insulating element ensures uniform melting of the powder binder.

[0051] After heating, the corresponding arrangement is cooled so that the powder binder adheres to the multiple layers of the preformed element building material 17, 26 to form the final preformed element 7. The mold 10, the air transport layer 12, the reusable forming element 22 and the vacuum foils 13, 19, 23, 29 are removed, and the final preformed element 7 (i.e. the inner and outer shell elements) is completed. Next, the blade 2 is manufactured using the preformed element 7, which is arranged on the blade half-mold (not shown), with the spar cap 9 sandwiched between them.

[0052] Next, another manufacturing process of the preformed element 7 according to the invention is carried out by means of Figures 11 to 13 Description. Reference Fig.11 A mold 10 is provided having a mold surface 11, the mold surface 11 being cleaned, and an air transmission layer 12 being placed on the mold surface 11 (see also Figure 4 Next, the lower vacuum foil 13 is arranged on top of the air transmission layer 12 and sealed on the edge 14 of the mold 10 by the butyl tape 15. Additionally, a conical or wedge-shaped forming element 22 is arranged between the air transmission layer 12 and the lower vacuum foil 13 so that it is arranged laterally on the preformed element building material 17 and between the mold surface 11 and the preformed element building material 17 (see Fig.12 Using the first outlet 16 , a vacuum is established between the mould surface 11 and the first lower vacuum foil 13 .

[0053] If with the help of Fig.14 visible, Fig.14 It passes along line XIV–XIV. Fig.12 The preformed element building material 17 is composed of a plurality of stacked fiber sheets 18. The fiber sheets 18 include equal widths so that on the other edge of the preformed element building material 17 (not on the Fig.14 ) automatically produces the same shape as provided by the forming element 22.

[0054] Next, if Fig.13 As can be seen in FIG. 1 , the upper vacuum foil 19 is arranged on top of the preformed element building material 17 and is sealed on the edge 14. The vacuum is then drawn between the vacuum foils 13, 19 through the second outlet 21 and the vacuum foils 13, 19 are then welded together.

[0055] Optionally, with the aid of Figures 7 to 10 The explained steps can then also be carried out in this exemplary embodiment.

[0056] Next, heat is applied to the arrangement, in particular through the mould 10, which acts as a heating means in order to activate the powder binder.After cooling and curing of the binder, the air transmission layer 12, the reusable conical forming element 22 and the vacuum foils 13, 19 are removed.

[0057] like Fig.15 As can be seen in FIG. 1 , in order to manufacture the blade 2, a plurality of preformed elements 7 (which have been Figures 11 to 14 The preformed elements 7 are arranged laterally adjacent to each other in the blade half-mould 31 for the blade 2. Since the preformed elements 7 comprise corresponding tapered lateral sections 32, which have been shaped by the tapered forming elements 22, the preformed elements 7 fit together perfectly at their edges.

[0058] Although the present invention has been described in detail with reference to the preferred embodiments, the present invention is not limited to the disclosed examples, and those skilled in the art will be able to derive other variations from the disclosed examples without departing from the scope of the present invention.

Claims

1. A method for manufacturing a preformed element (7) for a blade (2) for a wind turbine (1), comprising the steps of: a) arranging a preformed element building material (17, 26) comprising a curable binding agent on a molding surface (11) of a mold (10) such that the shape of the preformed element building material (17, 26) is adapted to the shape of the molding surface (11), b) arranging at least one shaping element (22) on or at the preformed element building material (17, 26) such that a shaping surface of the shaping element (22) defines a contact surface of the preformed element (7), wherein the shape of the shaping surface corresponds to a contact surface of a blade part, the contact surface of the blade part being arranged to be in contact with the contact surface of the preformed element (7) in the manufactured blade (2), and c) curing the preformed element building material (17, 26) so as to preserve the shape of the preformed element (7), the shape of the preformed element (7) being defined by the molding surface (11) and the forming element (22).

2. The method according to claim 1, characterized in that At least one first preformed element building material (17) is arranged on the molding surface (11), wherein the forming element (22) is or includes at least one second preformed element building material (26), and the second preformed element building material (26) is arranged on or at the first preformed element building material (17).

3. The method according to claim 2, characterized in that Another forming element (22) is sandwiched between the first preform element building material (17) and the second preform element building material (26).

4. The method according to one of the preceding claims, characterized in that The shape of the shaped surface of the at least one shaped element (22) corresponds to the shape of the contact surface of the blade part, be it a spar cap (9) or a spar or a blade root or a core (24).

5. The method according to one of the preceding claims, characterized in that The at least one forming element is a conical forming element (22), and wherein the conical forming element (22) is arranged laterally on the preform element building material (17) and between the mold surface (11) and the preform element building material (17), wherein the blade part is another preform element (7), and the other preform element (7) is arranged to be laterally adjacent to the preform element (7) in the manufactured blade (2), and wherein the contact surface of the blade part is conical.

6. The method according to one of the preceding claims, characterized in that The preformed element building material (17) is arranged between a lower vacuum foil (13) and an upper vacuum foil (19), wherein a vacuum is created between the mold surface (11) and the lower vacuum foil (13) and between the lower vacuum foil (13) and the upper vacuum foil (19).

7. The method according to claim 2 or 3 and claim 6, characterized in that The first preform element building material (17) is arranged between a first lower vacuum foil (13) and a first upper vacuum foil (19), wherein the second preform element building material (26) is arranged between the second lower vacuum foil (23) and the second upper vacuum foil (29), wherein a vacuum is generated between the mold surface (11) and the first lower vacuum foil (13), between the first lower vacuum foil (13) and the first upper vacuum foil (19), between the first upper vacuum foil (19) and the second lower vacuum foil (23), and between the second lower vacuum foil (23) and the second upper vacuum foil (29).

8. The method according to one of the preceding claims, characterized in that The preformed element building material (17, 26) comprises at least one layer, in particular a plurality of stacked layers, made of a fiber sheet material (18, 28) and / or a rigid core material (27).

9. The method according to claim 8, characterized in that The adhesive agent is a heat-fusible powder adhesive.

10. Preformed element for a blade (2) of a wind turbine (1), said preformed element being manufactured by a method according to one of the preceding claims.

11. A blade for a wind turbine (1), comprising at least one preformed element (7) according to claim 10.

12. Wind turbine comprising at least one blade (2) according to claim 11.

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