ROTOR BLADE COMPONENT, METHOD FOR THE PRODUCTION THEREOF AND WIND TURBINE

Description

[0001] The invention relates to a method for producing a rotor blade component, in particular a rotor blade belt, for a rotor blade of a wind turbine, a rotor blade component and a wind turbine with such a rotor blade component.

[0002] Rotor blades for wind turbines are often assembled from two separately manufactured rotor blade shells. One or more belts may be provided inside the rotor blade. These belts run essentially along a longitudinal axis of the rotor blade from the rotor blade root to the rotor blade tip, providing additional stability and influencing the elastic properties of the rotor blade.

[0003] Such belts are generally manufactured using pultrusion processes, where, for example, individual pultruded layers of a fiber material, e.g. carbon fiber, are layered and bonded together to form the belt. In order to reduce the risk of the end of a layer detaching from the layer below, it is known to bevel the ends of the layers, e.g. by milling, grinding or sawing, thus reducing the thickness at the end of the layer and thus ensuring a continuous flow of forces between the ending layer and the layer below. For technical reasons, however, it is difficult to reduce the thickness at the end of the layer to zero when beveling. This means that a residual thickness remains, which is why there is generally also a residual risk of detachment.

[0004] EP2778393 A2 discloses a wind turbine blade formed from a first and a second half-shell, each half-shell having, inter alia, a spar cap comprising a plurality of stacked, pultruded layers which are flat in a chord direction and whose ends are tapered to reduce stress concentrations in each individual layer.

[0005] EP3026259 A1 discloses methods for producing spar caps for a rotor blade of a wind turbine. The method comprises providing a plurality of pultrusion profiles consisting of one or more fibers or fiber bundles cured by a resin material. A further step consists in tapering the ends of the pultrusion profiles at a predetermined angle. The method also comprises arranging the tapered pultrusions in a mold to form the spar cap. The method pe.

[0006] CN103817955 A discloses a manufacturing method for a composite spar cap for wind turbine blades. For the main spar caps used for 50 m long wind turbine blades, the number of plies is typically determined according to the product specification plan for the wind turbine blades, e.g., 65 fiber layers. The fiber length of the plies is determined according to the length of the wind turbine blade in accordance with the design requirements for the main spar cap, with the fiber length of each ply generally being different. It is an object of the invention to provide an improved rotor blade component, in particular to increase the load-bearing capacity of a rotor blade component.

[0007] This object is achieved by a method for producing a rotor blade component according to claim 1, a rotor blade component according to claim 9, and a wind turbine according to the independent claims.

[0008] According to a first aspect of the invention, in a method for producing a rotor blade component, in particular a rotor blade belt, for a rotor blade of a wind turbine, a layer system is produced from a first layer made of a first material and a second layer made of a second material. The second material has a lower modulus of elasticity than the first material, and the second layer extends at least partially along the first layer. The layer system is beveled at at least one end using at least one separating process in such a way that the second layer projects beyond the first layer at at least one end of the layer system. In addition, the layer system is joined to at least one further such layer system to form the rotor blade component.

[0009] According to a second aspect of the invention, a rotor blade component, in particular a rotor blade belt, for a rotor blade of a wind turbine, preferably produced using the method according to the first aspect of the invention, has at least one layer system consisting of a first layer made of a first material and a second layer made of a second material. The second layer is applied at least partially to the first layer, and the second material has a lower modulus of elasticity than the first material. In addition, the layer system is beveled at at least one end such that the second layer projects beyond the first layer at at least one end of the layer system. The rotor blade component furthermore has at least one further such layer system, with which the at least one layer system is connected to the rotor blade component.

[0010] According to a third aspect of the invention, a wind turbine has at least one rotor blade which has a rotor blade component produced by the method according to the first aspect of the invention and / or a rotor blade component according to the second aspect of the invention.

[0011] Preferably, such layer systems are connected to one another in such a way that the second layer of a first layer system rests, in particular completely, on the first layer of a second layer system in the region of its at least one bevelled end and / or the second layer of a first layer system faces the first layer of a second layer system in the region of its at least one bevelled end. The second layer of the first layer system can lie directly on the first layer of the second layer system. Alternatively, however, at least one further layer, for example an adhesive layer and / or a layer of thin fleece or of fiber material impregnated with resin, can lie between the second layer of the first layer system and the first layer of the second layer system.

[0012] Preferred aspects of the invention are based on the approach of producing a rotor blade component, such as a rotor blade belt, from multiple layer systems, wherein each layer system preferably takes the form of a layer composite and comprises a first layer made of a first material and a second layer made of a second material. The second material has a lower modulus of elasticity than the first material, so that the stiffness of the second layer is lower than the stiffness of the first layer, even if the two layers have the same thickness.

[0013] The layer systems can each be chamfered at at least one end so that the second layer protrudes beyond the first layer at at least one end. By chamfering the layer system at at least one end, which can also be referred to as scarfing the layer system, an end surface of the layer system, in particular of the first layer, is created. The end surface is inclined with respect to a contact surface between the first and second layers, in particular so that the first layer ends in a wedge shape or the thickness at the end of the first layer approaches zero. When several such layer systems are joined together, a pyramid-like stack with high load-bearing capacity is preferably produced, since sudden changes in stiffness at the ends of the first layers can be avoided and the risk of detachment is reduced.Preferably, the layer systems are connected to one another in such a way that the second layers face the first layers of the respective underlying layer system.

[0014] Since the stiffness of the layer system is reduced in the area of ​​the second layer, stiffness jumps between the individual layer systems or within the rotor blade component and thus the risk of the individual layer systems detaching from one another can be reduced. At the same time, the lower stiffness of the second layer also affects the potential bevel angle at which part of the layer system, in particular the first layer, is separated, e.g., by milling, cutting, grinding or sawing. For example, the bevel angle can be selected to be larger than for conventional layers of rotor blade components due to the second layer with lower stiffness, thus reducing the costs of manufacturing the scarf joints. In addition, the ends of the individual layer systems can be located closer together.It is conceivable, for example, to chamfer at least one end of the layer system in such a way that the at least one end has a slope corresponding to the chamfer angle of between 1:50 and 1:200, in particular substantially 1:80, relative to the contact surface between the first and second layers.

[0015] A layer system can, for example, be formed from extruded or pultruded carbon fibers, which form the first layer, and a glass fiber scrim, which forms the second layer. When beveling at least one end of the layer system, at least one edge of the carbon fiber layer is preferably severed, so that the carbon fiber layer tapers towards the end, in particular tapering to a point or wedge-shaped at the bevel angle. Optionally, at least one edge of the glass fiber scrim can also be severed during beveling, so that the glass fiber scrim also tapers towards the end, whereby the stiffness of the second layer can be further reduced towards the end.

[0016] Overall, the invention improves the manufacture of rotor blades and provides a corresponding wind turbine.

[0017] In a preferred embodiment, the layer system is produced by joining the second layer made of the second material to the first layer during production of the first layer made of the first material. For example, the first layer can be produced on the second layer or at least partially around the second layer. It is conceivable, for example, for the first material to be pultruded in a pultrusion process and preferably deposited on the second layer and / or around the second layer. This allows the layer system to be produced in very few work steps. In particular, this also makes it possible to create a particularly strong connection between the first and second layers.

[0018] In particular, the second layer can be incorporated into the first layer or into a partial layer of the first material during production of the first layer from the first material. It is advantageous, for example, if the second material, e.g. as a glass fiber fabric or glass fiber bundle (so-called rovings), is already introduced as a second layer during production of the first layer. This allows the fiber bundles and fiber fabrics to bond reliably to the first layer, although the contact surface between the fiber bundles or fiber fabrics and the first layer can be uneven. In particular, this can result in an irregular, preferably continuous transition between the first and second layers when at least one end is beveled. This is particularly preferred because it can delay the formation of a crack front and thus detachment under high longitudinal loads.

[0019] The introduction of fiber bundles has the advantage, particularly compared to scrims, that the fiber bundles can also be introduced at the lateral edges of the first layer running along the longitudinal direction. Particularly preferably, during production of the first layer, fiber bundles (rovings) are introduced in such a way that at least part of the first layer is laterally enclosed by the fiber bundles. If appropriate, the introduced fiber bundles can also enclose a fiber scrim. This ensures that the elastic properties of the layer system in the region of the at least one beveled end are essentially determined by the second layer.

[0020] In a further preferred embodiment, the first layer made of the first material and the second layer made of the second material are manufactured separately, the layer system being produced by applying the second layer to the first layer. This ensures in a particularly simple manner that the second layer, at least in the region of the at least one beveled end, extends completely along the first layer, in particular also at or up to its lateral edges, i.e., perpendicular to the longitudinal direction across the entire width of the first layer.

[0021] In a further preferred embodiment, the second layer is connected or applied only in a region of at least one end of the first layer, in which the layer system is beveled. This allows for savings in material and weight of the layer system or the rotor blade component. Furthermore, it is possible to vary the elastic properties of the rotor blade component in sections in the longitudinal direction.

[0022] In a further preferred embodiment, the layer system is bevelled at at least one end using the at least one separation process in such a way that the end of the second layer projecting beyond the first layer has a substantially rectangular end face, in particular running perpendicular to the longitudinal direction, and / or a finite layer thickness. The height of the side face or the thickness of the second layer is preferably at least half the average thickness of the second layer, in particular at least half the thickness of the second layer outside the region of the at least one bevelled end. The layer system can, for example, bevelled such that the side face has a height or the second layer has a thickness at the bevelled end of substantially 0.5 mm.This makes it possible to avoid the stiffness of the second layer in the area where it projects beyond the first layer being so low that it is damaged, for example, during the at least one separation process and / or when joining several layer systems.

[0023] In a further preferred embodiment, the at least one beveled end of the layer system is covered with a third layer made of a third material. The third material preferably has a modulus of elasticity, in particular in the longitudinal direction, that is greater than the modulus of elasticity of the second and / or first layer. Alternatively, the third material can also be the same as the first or second material. By covering the at least one beveled end with the third layer, the peeling load on the at least one end is reduced and an additional load path is provided for the flow of forces from the ending layer system.

[0024] In a further preferred embodiment, the layer system is beveled in such a way that the layer system, in the region of the at least one beveled end, has an end face which is inclined with respect to a contact surface between the first and second layers, and two opposing side end faces, in particular connected by the end face, which run essentially perpendicular to the contact surface between the first and second layers and are inclined with respect to one another such that they converge towards the end of the layer system. In other words, the layer system can be beveled in such a way that it tapers to a point in the region of the beveled end or forms a halved truncated pyramid, wherein the two opposing side end faces, together with the end face, form at least part of the lateral surface of the truncated pyramid.This makes it possible to ensure that the elastic properties of the layer system in the region of the at least one bevelled end are determined by the second layer, even if the second layer outside the region of the bevelled end does not extend to or up to the lateral edges of the first layer, ie not over the entire width of the first layer.

[0025] In a further preferred embodiment, the second layer has a smaller thickness than the first layer. This allows the load-bearing capacity of the layer system to be essentially determined by the first layer. In particular, this makes it possible to achieve a load-bearing capacity of the rotor blade component that is essentially comparable to the load-bearing capacity of conventional rotor blade components.

[0026] In a further preferred embodiment, the first layer has a thickness between 1 mm and 10 mm, preferably between 2 mm and 5 mm. Alternatively or additionally, the second layer has a thickness between 0.1 mm and 1 mm, preferably between 0.2 mm and 0.5 mm. This ensures sufficient load-bearing capacity of the layer system or the rotor blade component while simultaneously reducing the risk of the layers detaching from one another. In particular, this achieves an optimal ratio between the layer thicknesses of the first and second layers, providing the highest load-bearing capacity with a reduced risk of detachment.

[0027] In a further preferred embodiment, the first material has a modulus of elasticity in the longitudinal direction between 5 10 4< N / mm 2 < and 50 10 4< N / mm 2 <, preferably between 10 10 4< N / mm 2 < and 30 10 4< N / mm 2 <. Alternatively or additionally, the second material has a modulus of elasticity in the longitudinal direction between 1 10 4< N / mm 2 < and 6 10 4< N / mm 2 <, preferably between 4 10 4< N / mm 2 < and 5 10 4< N / mm 2 <. The first material or the first layer can, for example, comprise carbon fibers and can in particular be designed as a woven fabric or non-crimp fabric. The second material or the second layer can, for example, comprise glass fibers and can in particular be designed as a woven fabric or non-crimp fabric. It is also conceivable that the first and / or second material comprises fiber bundles (so-called rovings) and the first or second layer contains at least one such fiber bundle, in particular is formed from one or more such fiber bundles.

[0028] In a further preferred embodiment, the first material and the second material comprise fibers, wherein the proportion of fibers that run substantially along the longitudinal direction is lower in the second material than in the first material. In this case, the first material can otherwise correspond to the second material, i.e. the first material can be the same as the second material. The first material or the first layer can, for example, comprise carbon fiber fabric in which the carbon fibers extend substantially along the longitudinal direction. The second material or the second layer can also comprise a carbon fiber fabric, but in which the carbon fibers extend at an angle to the longitudinal direction, e.g. at 45° or even at 90° or perpendicular to the longitudinal direction. This makes it possible to reliably reduce the modulus of elasticity in the longitudinal direction at the transition from the first layer to the second layer.

[0029] Further advantages, features, and possible applications of the present invention will become apparent from the following description in conjunction with the figures. They show: Fig. 1 shows an example of an end of a layer system comprising a first layer and a second layer in a side view; Fig. 2 shows an example of an end of a layer system comprising a first layer and a second layer in a three-dimensional representation; and Fig. 3 shows an example of an end of a rotor blade belt in a side view.

[0030] Figure 1shows an example of an end of a layer system 10 comprising a first layer 1 made of a first material, e.g., carbon fibers, and a second layer 2 made of a second material, e.g., glass fibers, in a side view. The second layer 2 has a lower modulus of elasticity in a longitudinal direction L than the first layer 1. Furthermore, the second layer is significantly thinner, in particular, substantially by a factor of 10, than the first layer.

[0031] According to the invention, the layer system 10 has a beveled end with an end surface 3 which is inclined by a bevel angle α with respect to a contact surface 4 between the first and second layers 1, 2. The end surface 4 extends over the entire thickness of the first layer 1 and at least part of the second layer 2, so that the first layer 1 tapers to a point at the bevel angle α in the side view shown, while the second layer 2 has a blunt end, i.e. an end with an end face 2a oriented perpendicular to the contact surface 4. The second layer 2 protrudes beyond the first layer 1.

[0032] At the outermost end, the thickness of the layer system 10 is smaller than the thickness of the second layer 2 outside the beveled region, in particular substantially half as large.

[0033] Such a geometry of the end of the layer system 10 can be achieved, for example, by removing a part of the first and second material by at least one separation process. The removed material or material to be removed is Figure 1 marked by hatching.

[0034] For example, the layer system 10 can be arranged perpendicular to the contact surface 4, e.g. along the Figure 1 drawn dashed line, so that the end of the layer system 10 is formed. The end surface 3 can then be produced, for example, by milling. Alternatively, in the reverse order, the end surface 3 could of course also be produced by milling at an existing end of the layer system 10 and the resulting tip of the second layer 2 could then be sawn off.

[0035] Figure 2shows a second example of an end of a layer system 10 comprising a first layer 1 made of a first material and a second layer 2 made of a second material in a three-dimensional representation. The end of the layer system 10 is bevelled in such a way that it has an end surface 3 which is opposite a contact surface between the first and second layers 1, 2 (see Figure 1 ) is inclined. This forms a wedge-shaped end of the first layer 1. The boundary of the end surface 3 is in Figure 2 indicated by lines 3a and 3b.

[0036] The layer system 10 is preferably produced by means of a pultrusion process, so that the first layer 1 consists of carbon fibers arranged along a longitudinal direction L. During the pultrusion process, the second layer 2, e.g. a glass fiber fabric or a carbon fiber fabric or woven fabric, in particular with fibers arranged at an angle to the longitudinal direction L, can be incorporated. In particular, it is conceivable to introduce the second material during pultrusion of the first material, so that the second layer 2 is enclosed laterally by the first layer 1, ie in a transverse direction Q transverse to the longitudinal direction L.

[0037] To ensure that these borders do not influence the elastic properties of the layer system 10 in the region of the end in which the layer system 10 is bevelled, the layer system 10 can also be bevelled laterally, e.g. by cutting off a wedge-shaped part at the lateral edge of the layer system 10. This allows the second layer 2 to extend continuously from one side of the layer system 10 to the opposite side in the transverse direction Q in the region of the end of the layer system 10. This case is in Figure 2 on the left side of the layer system 10 facing the viewer. During the lateral bevel, a side end surface 2b is created, so that the elastic properties of the layer system 10 are maintained at least in the area in which the second layer 2 projects beyond the first layer 1 (see Figure 1 ), are essentially determined by the elastic properties of the second layer 2 in this area.

[0038] Alternatively, it is also possible to ensure during the pultrusion of the layer system 10 that the second layer 2 extends continuously from one side of the layer system 10 to the opposite side along the transverse direction Q, for example by inserting the second material in the form of a fiber bundle (so-called roving) at the lateral ends during the pultrusion of the first material. This creates elongated, in particular strip-shaped, regions 5 of low stiffness, which extend laterally of the second layer 2 along the longitudinal direction L and laterally border the second layer 2. This case is in Figure 2 shown on the right side of the layer system 10 facing away from the viewer.

[0039] Figure 3shows a side view of a rotor blade belt 100 formed from three layer systems 10 stacked one above the other. The layer systems 10 are arranged such that a second layer of a layer system 10 made of a second material faces a first layer of an adjacent layer system 10 made of a first material. The layer systems 10 are bonded to one another via adhesive layers 6 located between the layer systems 10.

[0040] The layer systems 10 have beveled ends that are staggered along a longitudinal direction L of the layer systems 10. This results in a pyramid-shaped structure of the rotor blade belt 100. End surfaces 3 created by beveling the ends can be aligned such that the layer systems 10 form flattened steps toward the end of the rotor blade belt 100.

Claims

1. A method of manufacturing a rotor blade component, in particular a rotor blade spar cap (100), for a rotor blade of a wind energy installation, wherein - a layer system (10) is manufactured from a first layer (1) of a first material and a second layer (2) of a second material, wherein the second layer (2) extends at least partially along a longitudinal direction (L) of the first layer (1) and the second material has a smaller modulus of elasticity in the longitudinal direction (L) than the first material, - the layer system (10) is bevelled at least at one end with the aid of at least one separation process in such a way that the second layer (2) projects beyond the first layer (1) at the at least one end of the layer system (10), and - the layer system (10) is connected to at least one further layer system (10) so as to form the rotor blade component characterized in that the layer system (10) is bevelled at the at least one end with the aid of the at least one separation process in such a way that a part of the first and second materials is removed, so that the layer system (10) has a bevelled end with an end surface (3) which is inclined by a bevel angle (α) with respect to a contact surface (4) between the first and second layers (1, 2) and extends over the entire thickness of the first layer (1) and at least part of the second layer (2), so that the first layer (1) tapers to a point at the bevel angle (α), while the second layer (2) which projects beyond the first layer (1) has a blunt end with an end face (2a) which is oriented perpendicular to the contact surface (4).

2. The method according to claim 1, wherein the layer system (10) is manufactured by incorporating the second material into a partial layer of the first material during the course of the manufacture of the first layer (1) from the first material, and thereby forming the second layer (2).

3. The method according to claim 1, wherein the first layer (1) is manufactured from the first material separately from the second layer (2) being manufactured from the second material, and the layer system (10) is manufactured by applying the second layer (2) onto the first layer (1).

4. The method according to any one of the claims 2 or 3, wherein the second layer (2) is incorporated or applied only in a region of the at least one end of the first layer (1) in which the layer system (10) is bevelled.

5. The method according to any one of the preceding claims, wherein the end face (2a) is rectangular.

6. The method according to any one of the preceding claims, wherein the height of the end face (2a) is at least half as great as the thickness of the second layer (2) outside of the region of the at least one bevelled end.

7. The method according to any one of the preceding claims, wherein the at least one bevelled end of the layer system (10) is covered with a third layer of a third material.

8. The method according to any one of the preceding claims, wherein the layer system (10) is bevelled in such a way that, in the region of the at least one bevelled end, the layer system (10) has an end face (3) which is inclined with respect to a contact surface (4) between the first and the second layer (1, 2), and two side end faces (2b) which are opposite to one another, which run substantially perpendicular to the contact face (4) between the first and the second layer (1, 2) and are inclined with respect to one another in such a way that they taper towards the end of the layer system (10).

9. A rotor blade component, in particular a rotor blade spar cap (100), for a rotor blade of a wind energy installation, wherein the rotor blade component comprises - at least one layer system (10) from a first layer (1) of a first material and a second layer (2) of a second material, wherein the second layer (2) is at least partially applied to the first layer (1) along a longitudinal direction (L), and the second material has a smaller modulus of elasticity in the longitudinal direction (L) than the first material, and the layer system (10) is bevelled at least at one end in such a way that the second layer (2) projects beyond the first layer (1) at the at least one end of the layer system (10), and - at least one further layer system (10) to which the at least one layer system (10) is connected so as to form the rotor blade component, characterized in that the layer system (10) is bevelled at the at least one end in such a way that a part of the first and second materials is removed, so that the layer system (10) has a bevelled end with an end surface (3) which is inclined by a bevel angle (α) with respect to a contact surface (4) between the first and second layers (1, 2) and extends over the entire thickness of the first layer (1) and at least part of the second layer (2), so that the first layer (1) tapers to a point at the bevel angle (α), while the second layer (2) which projects beyond the first layer (1) has a blunt end with an end face (2a) which is oriented perpendicular to the contact surface (4).

10. The rotor blade component according to claim 9, wherein the second layer (2) has a smaller thickness than the first layer (1).

11. The rotor blade component according to any one of the claims 9 or 10, wherein the first layer (1) has a thickness of between 1 mm and 10 mm, preferably between 2 mm and 5 mm, and / or the second layer (2) has a thickness of between 0.1 mm and 1 mm, preferably between 0.2 mm and 0.5 mm.

12. The rotor blade component according to any one of the claims 9 to 11, wherein the first material has a modulus of elasticity in the longitudinal direction (L) of between 5 × 104 N / mm2 and 50 × 104 N / mm2, preferably between 10 × 104 N / mm2 and 30 × 104 N / mm2, and / or the second material has a modulus of elasticity in the longitudinal direction (L) of between 1 × 104 N / mm2 and 6 × 104 N / mm2, preferably between 4 × 104 N / mm2 and 5 × 104 N / mm2.

13. The rotor blade component according to any one of the claims 9 to 12, wherein the first material and the second material comprises fibres and wherein the proportion of fibres which extend substantially along the longitudinal direction (L) is smaller in the second material than in the first material.

14. A wind energy installation comprising at least one rotor blade which comprises a rotor blade component which has been manufactured using the method according to any one of the claims 1 to 8 and / or which comprises a rotor blade component according to any one of the claims 9 to 13.