Method for manufacturing a component for a wind turbine

Abstract

A method for manufacturing a component for a wind turbine is provided. In a first step, a fiber material is laid onto a mold surface. In a further step, an uncured foam material is provided on top of the fiber material. Thereafter, the uncured foam material is cured to form a core member. Then, a resin impregnating the fiber material is cured to form the component. Thus, a core member for a component of a wind turbine can be provided easily.

Claims

1. A method for manufacturing a blade for a wind turbine, comprising a) laying a fiber material onto one of a vacuum distribution layer and a surface of a mold, b) providing an uncured foam material to the mold and on top of the fiber material, c) curing the uncured foam material in the mold to form a core member, d) impregnating the fiber material with a resin; and e) curing the resin impregnating the fiber material to form the blade in the mold; wherein in or after step b) the mold has an arcuate curvature to shape the foam material in accordance with a desired geometry of the blade; wherein step b) is performed by an applicator comprising a geometry corresponding to the desired geometry of the blade, and wherein said applicator is moved across the mold and the foam material to shape the foam material.

2. The method of claim 1, wherein in step b) the uncured foam material is applied to the fiber material in a foamed condition.

3. The method of claim 1, wherein in step b) the uncured foam material is applied to the fiber material in an unfoamed condition, the foamed condition being obtained after application of the uncured foam material to the fiber material.

4. The method of claim 1, wherein the applicator comprises an opening for supplying the uncured foam material.

5. The method of claim 4, wherein the foam material is supplied to the opening of the applicator at the same time as the applicator is moved across applied foam material that has already been applied to the fiber material.

6. The method of claim 4, wherein the geometry of the applicator comprises a scraping edge that is aligned with the opening.

7. The method of claim 1, wherein the applicator is configured to apply a covering layer on top of the foam material.

8. The method of claim 1, wherein in step b) the uncured foam material comprises chopped fibers.

9. The method of claim 8, wherein at least some of the chopped fibers each have a length less than the height of the formed core member.

10. The method of claim 1, further comprising laying a further fiber material on the cured foam material in the mold after step c).

11. The method of claim 1, wherein in step b) a strip of fiber material is provided between adjacent edges of layers of the uncured foam material.

12. The method of claim 1, wherein the foam material is polyurethane.

13. The method of claim 1, wherein step a) comprises laying the fiber material onto the vacuum distribution layer and wherein the method further comprises: laying the vacuum distribution layer onto the mold surface prior to step a); connecting the vacuum distribution layer to a vacuum pump; covering the vacuum distribution layer, the fiber material, and the foam material with a vacuum bag; applying suction between the mold surface and the vacuum bag with the vacuum pump.

14. The method of claim 13, further comprising: injecting resin between the mold surface and the vacuum bag after the applying suction step; applying heat to perform step e) and form the blade of the wind turbine; and removing the blade of the wind turbine from the mold after step e).

15. The method of claim 1, wherein step b) comprises: supplying foam material through a first supply line of the applicator to a mixing chamber; supplying chopped fibers through a second supply line of the applicator to the mixing chamber; mixing the foam material and the chopped fibers in the mixing chamber; supplying a mixture of the foam material and the chopped fibers from the mixing chamber to the top of the fiber material.

16. The method of claim 1, wherein the geometry of the applicator essentially includes a scraping edge and wherein the desired geometry of the foam material is a flat or planar top surface.

17. The method of claim 1, wherein the geometry of the applicator comprises a triangular cutout or zig-zag cutout and wherein the desired geometry of the foam material comprises a triangular shape.

18. The method of claim 17, wherein the desired geometry comprises a triangular recess and wherein the method further comprises providing the uncured foam material with the applicator to fill up the triangular recess after step b).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further objects, features and advantages of the present invention become apparent from the subsequent description and depending claims, taken in conjunction with the accompanying drawings, in which:

(2) FIG. 1 is a perspective view of a wind turbine according to one embodiment;

(3) FIG. 2 shows a section view from a VARTM-process according to an embodiment of a method for manufacturing a component for a wind turbine;

(4) FIG. 3 shows a flowchart in accordance with an embodiment of a method for manufacturing a component for a wind turbine;

(5) FIG. 4 shows a section view from a process step in accordance with an embodiment of a method for manufacturing a component for a wind turbine;

(6) FIG. 5A to FIG. 5C show a method with some modifications compared to the method of FIG. 4;

(7) FIG. 6 shows a method with some further modifications compared to FIG. 4;

(8) FIG. 7 shows, in a perspective view, adjacent bars or layers of foam material; and

(9) FIG. 8 shows, in a perspective view, adjacent bars of bars or layers of foam material and a fiber strip or tape.

(10) In the Figures, like reference numerals designate like or functionally equivalent elements, unless otherwise indicated.

DETAILED DESCRIPTION OF INVENTION

(11) FIG. 1 shows a wind turbine 1 according to an embodiment.

(12) The wind turbine 1 comprises a rotor 2 connected to a generator (not shown) arranged inside a nacelle 3. The nacelle 3 is arranged at the upper end of a tower 4 of the wind turbine 1.

(13) The rotor 2 comprises three blades 5. Rotors 2 of this kind may have diameters ranging from, for example, 30 to 120 meters. The blades 5 have an arcuate curvature and are subjected to high wind loads. At the same time, the blades 5 need to be lightweight. For these reasons, blades 5 in modern wind turbines 1 are manufactured from fiber-reinforced composite materials. Therein, glass fibers are generally preferred over carbon fibers for cost reasons. In addition, the blades 5 each comprise one or more core members made of a light material to reduce the weight of the blades 5. Presently, it is envisaged to manufacture the blades 5 with core members made from plastic foam, in particular polyurethane.

(14) This process will hereinafter be described in more general terms referring to FIGS. 2 and 3 initially.

(15) FIG. 2 shows a mold 6, which may be configured as an open or closed mold. For example, the mold 6 may form a lower part of a closed mold, the upper part of the closed mold not being shown.

(16) Initially, a vacuum distribution layer 7 is laid on top of a mold surface 6a, for example. The vacuum distribution layer 7 is connected to a vacuum pump 8, the function of which will be explained in more detail later.

(17) Now, in a first step S1 also illustrated in FIG. 3, a fiber material 9 is laid on top of the vacuum distribution layer 7. The fiber material 9 may, for example, comprise a fiber mat, a fiber layup, woven fibers or the like. The fibers may be arranged in a UD-configuration, a biax configuration or any other suitable configuration. The fiber material 9 comprises, for example, glass fibers and is applied to the vacuum distribution layer 7 in a dry state. In other embodiments, no vacuum distribution layer 7 is provided. In this case, the fiber material 9 is applied directly to the top surface 6a of the mold 6.

(18) In a step S2, a foam material 10, in particular polyurethane, is applied on top of the fiber material 9. When the foam material 10 is applied to the fiber material 9, it is already in the foamed condition. In other embodiments, the foam material 10 may be of such a chemical composition that the foamed condition will only be obtained after the application of the foam material 10 on top of the fiber material 9.

(19) In a further step S3, the foam material 10 is cured to form a core member. Curing may take place at room temperature or at an elevated temperature, for example, 100 C. During curing, molecular chains in the polyurethane are cross-linked to provide a hard and sturdy core member.

(20) In another step, a further layer of fiber material 11 may be applied to the cured foam material 10.

(21) Thereafter, the layup comprising the layers 7, 9, 10, 11 is covered in a vacuum bag 12. Now, suction is applied between the inner surface 6a of the mold 6 and the vacuum bag 12 to press the layup together. The suction is applied via the vacuum pump 8. The vacuum distribution layer 7 distributes the vacuum supplied by the vacuum pump 8. Once the vacuum has been applied, resin, for example an epoxy resin, is injected into the space between the vacuum bag 12 and the mold 6. The resin impregnates the fibers of the fiber materials 9, 11. Once the fibers of the fiber materials 9, 11 have been sufficiently wetted by the resin, heat is applied to the layup to cure the resin. The step of injecting the resin is indicated by step S4 in FIG. 3, the step of curing the resin to form a blade 5 is illustrated by step S5 in FIG. 3. In a step S6, the cured blade 5 may be removed from the mold 6.

(22) In another embodiment, instead of the dry fiber materials 9, 11, pre-impregnated fiber material may be used. In this case, step S4 is not required.

(23) FIG. 4 shows a more specific example of how to implement step S2.

(24) An applicator 13 is used to apply the foam material 10. The applicator 13 is connected to a supply line (not shown) supplying the foam material 10 in a foamed condition from a tank or some other storage means.

(25) The applicator 13 has an opening 14, which may be configured as a nozzle, for example. Through the nozzle 14, the foam material 10 is applied on top of the fiber material 9. The applicator 13 also comprises a scraping edge 15 for shaping the foam material 10 that has already been deposited on the fiber material 9. In this manner, a layer of foam material 10 is obtained having a flat or planar top surface 16.

(26) FIGS. 5A to 5C describe the process illustrated by FIG. 4 with some modifications.

(27) According to FIG. 5A, the applicator 13 comprises a reel or spool 17. The spool 17 comprises wound-up paper 18, for example. The paper 18 is automatically deposited on the top surface 16 of the foam material 10, as the applicator 13 deposits the foam material 10 on top of the fiber material 9 and shapes the same with its scraping edge 15. The applicator 13 basically moves parallel to the plane, in which the fiber material 9 extends. The direction of motion of the applicator 13 is indicated by reference numeral 19 in FIG. 5A.

(28) According to one embodiment, the scraping edge 15 may have the shape of a triangular cutout as shown in FIG. 5B. As the applicator 13 moves over the deposited foam material 10, the foam material 10 is formed to a corresponding triangular shape. This is illustrated by FIG. 5C, which shows, in a cross-section, two triangular bars of foam material 10 arranged next to one another in a plane parallel to the plane of the fiber material 9. The applicator 13 may now be configured to fill up the triangular recess 20 between the triangular bars with foam material 10 in a further process step. In this further process step, the applicator 13 may be configured with a straight scraping edge 15, as for example explained in connection with FIG. 4.

(29) FIG. 6 shows a process step with some further modifications compared to FIG. 4.

(30) In the process illustrated in FIG. 6, the applicator 13 is connected to two supply lines 21, 22. Via the supply line 21, the foam material 10 is supplied. Via the supply line 22, chopped fibers 23, for example chopped glass, carbon or aramid fibers 23, are supplied. Further, the applicator 13 may comprise a mixing chamber 24, in which the foam material 10 is mixed with the chopped fibers 23. Said mixture is supplied by the applicator 13 onto the fiber material 9. Further embodiments described with respect to FIG. 4 as well as FIG. 5A to 5C apply mutatis mutandis to the embodiment of FIG. 6.

(31) Once cured, the foam material 10 is reinforced by the fibers 23. The fibers 23 may have a length smaller, equal or larger than the thickness or height H of the deposited layer 10. Thus, a fiber-reinforced core member is obtained of the curing.

(32) Also, the fibers may be arranged at different angles with respect to the plane 25 of the glass fiber material 9.

(33) The fibers 23, in particular a majority of the fibers 23, may be arranged perpendicularly to the plane 25.

(34) FIG. 7 illustrates an example of a foam material 10 with different fiber orientations.

(35) In the example of FIG. 7, the fibers 23 are arranged at a non-perpendicular angle with respect to the plane 25 of the fiber material 9 (not shown). For example, the fibers 23 may be arranged at angles of +45/45 with respect to the plane 25.

(36) For example, the foam material 10 may be comprised of three bars or layers 26, 26, 26. The bars or layers 26, 26, 26 are arranged next to each other, thus bordering with their side faces or edges 27 onto one another. The bars or layers 26, 26, 26 may be formed by the applicator 13 changing its direction of movement 19, 19, 19 two times by 180.

(37) FIG. 8 illustrates a further method of reinforcing the foam material 10.

(38) For example, the foam material 10 may again, as already described in connection with FIG. 7, be comprised of several bars or layers 26, 26, 26 being arranged side by side. Now, a fiber strip 28 comprising a biax fiber material, for example, is arranged between adjacent edges 27 of the bars or layers 26, 26, 26. The strip or tape 28 may be arranged such that it extends in a plane perpendicular to the plane 25 of the fiber material 9.

(39) Although the present invention has been described in accordance with preferred embodiments, it is obvious for a person skilled in the art that modifications are possible in all embodiments.