Mandrel for producing hollow composite component of wind turbine rotor blade

Abstract

There is provided a mandrel for producing a hollow composite component of a wind turbine rotor blade, the mandrel comprising a core (110) of a first material; an outer layer (120) of a second material disposed radially outward of the core (110), the second material being more compressible than the first material; and a first reinforcement part (130) for reinforcing the pressure on the first inner region of the ply, the first reinforcement part (130) being arranged at least partially radially outside of the core (110), wherein the first outer surface (135) of the first reinforcement component (130) and the second outer surface (125) of the outer layer (120) together form a defined shape corresponding to a desired inner shape of at least a portion of the hollow composite component.

Description

Technical Field

[0001] The present disclosure generally relates to a mandrel for producing a hollow composite component for a wind turbine rotor blade, a method for producing a hollow composite component for a wind turbine rotor blade using a mandrel, and a hollow composite component for a wind turbine rotor blade manufactured using a mandrel. Background Art

[0002] Generally, a wind turbine comprises a turbine having a rotor including a rotatable hub assembly with a plurality of blades. The blades convert wind energy into a mechanical rotational torque that drives one or more generators via the rotor. The generators are sometimes, but not always, rotationally coupled to the rotor via a gearbox. The gearbox steps up the inherently low rotational speed of the generator's rotor to efficiently convert the rotational mechanical energy into electrical energy, which is fed into the utility grid via at least one electrical connection. Gearless direct-drive wind turbines also exist. The rotor, generator, gearbox, and other components are typically mounted within a housing or nacelle, which is positioned atop a base, which can be a truss or tubular tower.

[0003] In wind turbines, rotor blades are large, monolithic composite structures. They are largely made of composites, feature bolted blade-to-hub connections and integrated lightning protection, and include various types of composite structural materials and elements. Each rotor blade may include multiple hollow composite components, such as hollow spars, such as box spars or D-spars.

[0004] In a conventional process for manufacturing hollow composite structures, a mandrel is used to define the hollow space. Fiber material or sheets (such as pre-impregnated glass fiber material) are laid onto the mandrel within a first mold section, with the position and shape of the fiber material on the mandrel essentially defining the composite part. A second mold section completes the mold, and the fiber material can be cured in a conventional vacuum resin curing process. This process can be used to produce strong and lightweight composite structures for wind turbine rotor blades.

[0005] EP3894194A1 describes a method for producing a hollow composite structure, such as a wing spar cross member used in a wind turbine blade, comprising placing a fiber reinforcement material around a mandrel in a mold, and curing the fiber reinforcement material. The mandrel is formed from a compressible material having a rigid neutral state, the material having a certain rigidity to maintain the defined shape of the mandrel during the laying and curing of the fiber reinforcement material. After curing, a vacuum is drawn on the mandrel to compress the compressible material so that the compressed mandrel can be pulled out through an opening in the composite structure, the opening being sized so that the mandrel cannot be pulled out through the opening in the rigid neutral state of the mandrel.

[0006] Therefore, there is a need for an improved mandrel for producing hollow composite components for wind turbine rotor blades. Summary of the Invention

[0007] The invention is defined by the appended claims.

[0008] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0009] According to one aspect, a mandrel for producing a hollow composite component for a wind turbine rotor blade is provided, the mandrel comprising a core of a first material, an outer layer of a second material arranged radially outwardly of the core, the second material being more compressible than the first material, and a first reinforcement component for reinforcing pressure on a first inner region of the layup, the first reinforcement component being at least partially arranged radially outwardly of the core, wherein a first outer surface of the first reinforcement component and a second outer surface of the outer layer together form a defined shape corresponding to a desired inner shape of at least a portion of the hollow composite component.

[0010] According to a further aspect, there is provided a method for producing a hollow composite component for a wind turbine rotor blade using a mandrel as described herein, the method comprising placing layups in a mould around the mandrel, and performing an in-mould curing process.

[0011] According to another aspect, there is provided a hollow composite component for a wind turbine rotor blade manufactured using a mandrel as described herein.

[0012] These and other aspects, embodiments, examples and advantages of the present invention will become better understood with reference to the following description and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A full and enabling disclosure, including the best mode thereof, to those skilled in the art is set forth in the specification with reference to the accompanying drawings, in which: Figure 1 is a schematic cross-section of a mandrel according to aspects described herein; Figure 2A is a schematic cross-section of a first reinforcement component in a non-expanded state according to embodiments described herein; Figure 2B is a schematic cross-section of a first reinforcement component in an expanded state according to embodiments described herein; Figure 3 is a schematic cross-section of a hollow portion according to embodiments described herein; Figure 4 is a schematic cross-section of a core according to embodiments described herein; Figure 5 is a schematic cross-section of a core and reinforcement component according to embodiments described herein; Figure 6 is a schematic cross-section of a core, reinforcement components, and outer layers according to embodiments described herein; Figure 7 is a schematic cross-section of a mandrel according to embodiments described herein; Figure 8 is a schematic diagram of a method for producing a hollow composite member according to aspects described herein; Figure 9 is a schematic diagram of a method for producing a hollow composite member according to an embodiment described herein; Figure 10 is a schematic cross-section of a wind turbine rotor blade; and Figure 11 is a schematic cross section of a hollow composite member. DETAILED DESCRIPTION

[0014] Reference will now be made in detail to the embodiments, one or more examples of which are illustrated in the accompanying drawings. Each example is provided to illustrate the present disclosure. Features shown or described as part of one example or embodiment may be used with another example or embodiment.

[0015] As stated above, the present invention is directed to an improved mandrel for producing hollow composite components, such as spars, for wind turbine rotor blades.

[0016] Composite materials generally include fiber reinforcements embedded in a matrix material (such as a polymer or ceramic material). The reinforcement material generally acts as the load-bearing component of the composite material, while the matrix material protects the reinforcement material, maintains the orientation of its fibers, and serves to distribute the load to the reinforcement material. Polymer matrix composite (PMC) materials are typically manufactured by impregnating a fabric with a resin and then curing it. Prior to impregnation, the fabric may be referred to as a "dry" fabric and typically comprises a stack of two or more fiber layers (plies or sheets). Depending on the intended application and the matrix material used, the fiber layers may be formed from a variety of materials, such as carbon (e.g., graphite), glass (e.g., fiberglass), polymers (e.g., ) and ceramics (e.g. )fiber.

[0017] In composite manufacturing, it is beneficial to produce well-compacted laminates with a specified resin-to-fiber ratio and no voids or defects. Common challenges include surface porosity, voids, resin-rich areas, and bridging.

[0018] Mandrels comprising compressible materials are susceptible to bridging. Bridging occurs when the initial or first fabric ply pulls away from and across a defined feature (e.g., a corner) rather than remaining tightly adhered to the feature. Bridging can lead to resin accumulation, an undesirable accumulation of excess resin beneath the first fabric ply, which can locally weaken the laminate.

[0019] Therefore, bridging can be a problem when producing hollow composite components. For example, in inside corners, the size of the radius is important. For example, it can be more difficult when the inside corner radius is small.

[0020] Bridging issues, such as those in interior corners, lead to resin accumulation and glass bridging separation. This results in additional weight due to the weight of the resin and, due to the increased exotherm caused by resin accumulation, can increase the risk of cracking. Since wind turbine rotor blades are weight-sensitive, the added weight is undesirable. Furthermore, substandard components (e.g., due to resin cracking or substandard curing) are often irreparable and result in part rejection. Resin accumulation can, at a minimum, lead to thermal degradation of the component and can further negatively impact safety temperature limits, such as ramping and cycling.

[0021] It is therefore desirable to provide a mandrel comprising a compressible material for producing a hollow composite member for a wind turbine rotor blade, wherein the mandrel is improved with respect to a desired shape of the hollow composite member having defined features, such as corners.

[0022] According to one aspect, a mandrel for producing a hollow composite component for a wind turbine rotor blade is provided, the mandrel comprising a core of a first material, an outer layer of a second material arranged radially outwardly of the core, the second material being more compressible than the first material, and a first reinforcement component for reinforcing pressure on a first inner region of the layup, the first reinforcement component being at least partially arranged radially outwardly of the core, wherein a first outer surface of the first reinforcement component and a second outer surface of the outer layer together form a defined shape corresponding to a desired inner shape of at least a portion of the hollow composite component.

[0023] Some further description is provided below, which can be referred to Figure 1 Come to understand.

[0024] The mandrel comprises a core 110 of a first material and an outer layer 120 of a second material. The first and second materials are compressible materials. The second material is more compressible than the first material. A compressible material can be understood as a material that has an uncompressed state and a compressed state.

[0025] Compressible material may be understood as a material capable of being placed in an uncompressed state, wherein the compressible material is formed into a defined shape. Compressible material may be understood as a material capable of being placed in an uncompressed state, wherein the compressible material has sufficient rigidity to maintain a defined shape during the layup and curing of the fiber reinforcement material placed around the mandrel.

[0026] A compressible material may be understood as a material that is capable of transitioning into a compressed state when a vacuum is applied thereto. A compressible material may be understood as a material that is sufficiently elastic to return to a non-compressed state when the vacuum applied thereto is released.

[0027] The first exterior surface 135 of the first reinforcement component 130 and the second exterior surface 125 of the outer layer 120 together form a defined shape corresponding to a desired interior shape of at least a portion of the hollow composite member.

[0028] The pressure on the first interior region of the layup can be understood as a compressive force on the layup. It will be appreciated that the mold or portion of the mold surrounding the mandrel and the layup, combined with the vacuum applied to the layup, enables the application of pressure or a compressive force to the first interior region of the layup. It will be appreciated that the recess or opening of the core 110 acts as a barrel wall.

[0029] A "layup" may be understood as a material(s) that forms or is used to form at least a portion of a hollow composite component. In particular, a "layup" may be understood as a fiber fabric and / or a composite material. In an example, the hollow composite component is a portion of a spar cross member, a spar cross member, a portion of a spar cross beam, or a spar cross beam. A hollow composite component, in particular a spar cross beam as described herein, may be understood as being manufactured to form an internal portion of a wind turbine rotor blade.

[0030] A "layup" may be understood to include or contain a material in a state prior to final or complete curing, for example including or containing uncured material, pre-cured material, and / or partially cured material.

[0031] A "layup" may be understood as a layer of material. In particular, a "layup" may be understood to include plies, such as mineral plies, polymer plies, glass plies, metal plies, carbon plies. A "layup" may be understood to include fibers, such as mineral fibers, polymer fibers, glass fibers, metal fibers, carbon fibers.

[0032] It will be appreciated that the polymeric fibers may comprise aromatic polyamide, polyethylene, polyurethane and / or aramid fibers.It will be appreciated that the fibers may be in the form of unidirectional or multidirectional fibers, prepregs, fiberboard or fiber mats.

[0033] In examples, a "layup" includes dry glass / carbon fiber fabric and / or prepreg.

[0034] In examples, a "layup" includes prefabricated material(s).

[0035] The expression “first reinforcement member for reinforcing pressure” may be understood as the first reinforcement member 130 for providing a higher pressure or a greater force than that provided when the first reinforcement member is replaced by a member of the second material.

[0036] For example, if the outer layer 120 is also arranged at the position where the first reinforcement component 130 was originally arranged, the pressure or force provided by the extended outer layer at the position where the first reinforcement component 130 was originally arranged is less than the pressure or force provided by the first reinforcement component 130 at the said position.

[0037] The first exterior surface 135 of the first reinforcement component 130 and the second exterior surface 125 of the outer layer 120 together form a defined shape corresponding to a desired interior shape of at least a portion of the hollow composite member.

[0038] In an example, the first outer surface 135 of the first reinforcement component 130 is a surface configured to be proximate to the first inner region of the layup. In an example, the first outer surface 135 of the first reinforcement component 130 is arranged (farthest) from the core.

[0039] In the example, the second outer surface 125 of the outer layer 120 is a surface configured to be adjacent to the second inner region of the laminate. As will be appreciated, the second inner region of the laminate is adjacent to the first inner region of the laminate.

[0040] It will be appreciated that the first outer surface 135 of the first reinforcement component 130 and the second outer surface 125 of the outer layer 120 have a common edge.

[0041] It will be appreciated that the first reinforcement component 130 having the hollow portion 210 in the expanded state and the outer layer 120 in the uncompressed state together form a defined shape corresponding to the desired interior shape of at least a portion of the hollow composite member.

[0042] It will be appreciated that the defined shape (formed together by the first outer surface 135 of the first reinforcement component 130 and the second outer surface 125 of the outer layer 120) and the desired shape (of at least a portion of the hollow composite member) is defined when the plies are laid up on the mandrel, in particular during the (in-mold) curing process.

[0043] In an example, the defined shape (of the mandrel) and the desired shape (of the hollow composite member) are the shapes of the mandrel and the hollow composite member, respectively, during the (in-mould) curing process.

[0044] It will be appreciated that the second interior region of the ply and the first interior region of the ply have a common edge.

[0045] It will be appreciated that the layup laid up on the mandrel, including the first exterior surface 135 of the first reinforcement component 130 and the second exterior surface 125 of the outer layer 120, is cured to form at least a portion of the hollow composite member, wherein at least a portion of the hollow composite member has a desired internal shape corresponding to the defined shape formed by the first exterior surface 135 of the first reinforcement component 130 and the second exterior surface 125 of the outer layer 120.

[0046] As a result, the performance of the mandrel is improved in terms of the desired shape of the hollow composite component with defined features (such as corners). As a result, the desired shape of the hollow composite component can be better achieved. As a result, undesirable effects such as bridging can be better avoided.

[0047] Some further description is provided below, which can be referred to Figure 2A and Figure 2B Come to understand.

[0048] According to an embodiment, the first reinforcement component 130 includes a hollow portion 210 that is expandable by pressurized fluid.

[0049] In an example, the hollow portion 210 is inflatable. In an example, the hollow portion 210 can be understood as an inflatable portion. In an example, the pressurized fluid is a gas (eg, air, nitrogen) or a liquid (eg, water).

[0050] According to an embodiment, the hollow portion 210 is arranged close to the core 110 and / or wherein the hollow portion 210 is at least partially surrounded by the core 110 .

[0051] In the example, the hollow portion is arranged at the first end of the first reinforcement component 130 , close to the core 110 .

[0052] In an example, the core 110 includes a recess or opening, such as a depression, cavity, slot, groove, or channel.

[0053] In an example, the recess of the core 110 or the opening of the core 110 is configured to hold the first reinforcement component 130 .

[0054] In an example, the recess or opening of the core 110 has an interior shape that is complementary to the shape of a portion of the first reinforcement component 130 .

[0055] In an example, the depressions or openings are oriented in a direction in which reinforcing pressure is to be applied to the first interior region of the laminate.

[0056] In an example, the recess or opening is oriented in the direction of the first interior region of the ply.

[0057] In the example, the axis of the recess or opening of the core 110 is oriented in the direction of the first inner region of the ply, this axis being located in the cross-sectional plane of the core 110 , this axis being preferably the axis of symmetry of the recess or opening.

[0058] According to an embodiment, the hollow portion 210 is fluidly isolated from the core 110 and the remainder of the first reinforcement component 130. In an example, the hollow portion 210 is fluidly isolated from the remainder of the first reinforcement component 130 and / or from the core 110 and / or the outer layer 120.

[0059] In an example, the hollow portion forms a fluid-tight volume except for the port.

[0060] It will be appreciated that the port can be in an open state (eg, to allow pressurized fluid to pass through the port) and in a closed state (eg, to prevent pressurized fluid from passing through the port).

[0061] In an example, the first reinforcement component 130 is less compressible or more rigid relative to the outer layer 120. In an example, the first reinforcement component comprises a material that is less compressible than the second material of the outer layer 120.

[0062] Thus, during the curing process (e.g., curing in an autoclave), pressure acting on a first interior region of the layup proximate the first reinforcement component 130 is intensified (or greater) relative to pressure acting on a second interior region of the layup proximate the outer layer 120.

[0063] As a result, the performance of the mandrel is improved in terms of the desired shape of the hollow composite component with defined features (such as corners). As a result, the desired shape of the hollow composite component can be better achieved. As a result, undesirable effects such as bridging can be better avoided.

[0064] As an illustrative example, hollow portion 210 is a 2 inch thick discharge hose providing 1.25 inches of radial expansion.

[0065] Some further description is provided below, which can be referred to Figure 3 Come to understand.

[0066] According to an embodiment, the hollow portion 210 includes at least one of the following group: a drop stitch 410 ; 420 , a continuous fiber, and a reinforcement for defining the shape of the hollow portion 210 in the expanded state 320 .

[0067] In an example, the hollow portion 210 in the expanded state 320 has a defined shape for reinforcing pressure on the first interior region of the laminate. In an example, the first interior region of the laminate includes defined features, such as corners.

[0068] In an example, the hollow portion 210 has a shape that is, for example, circular or triangular in cross-section, and / or is arranged so as to reinforce the pressure on the first interior region of the laminate at a point defining the minimum radius of the feature or along an axis defining the feature (e.g., at the apex of a corner) when in the expanded state 320.

[0069] Some further description is provided below, which can be referred to Figure 4 Come to understand.

[0070] The first material of the core 110 may be a foam material, such as a closed-cell foam.

[0071] Generally, the first material of core 110 can be (and further include) an incompressible material, such as a plastic or wood core. For example, core 110 can be rigid. In another example, core 110 can be hollow, for example, having an outer (rigid) structure, an empty interior, or an interior filled with a fluid (particularly air). For example, the empty interior can account for more than 50% of the volume of core 110.

[0072] The first material may be at least one of the following: a polymer, a rubber, polyethylene (EPE, XLPE), EVA, polypropylene, polystyrene, closed-cell EPDM foam rubber, preferably cross-linked polyethylene; having a density of at least 1 lb / cubic foot, preferably at least 2 lb / cubic foot; having a density of at most 4 lb / cubic foot, preferably at most 3 lb / cubic foot; as a specific example: L200 or cross-linked polyethylene.

[0073] Some further description is provided below, which can be referred to Figure 5 Come to understand.

[0074] According to an embodiment, the first reinforcement component 130 comprises a first intermediate portion 220 of a third material that is less compressible than the second material of the outer layer 120 , preferably wherein the first intermediate portion 220 comprises a closed-cell foam.

[0075] It will be appreciated that the first intermediate portion 220 may be less compressible or more rigid relative to the outer layer 120 and / or relative to the core 110 .

[0076] Thus, the first intermediate portion 220 enables a pressure reinforcement to be transferred to the first inner region of the ply.

[0077] According to an embodiment, the first reinforcement component 130 includes a second intermediate portion 230 that is less compressible than the first intermediate portion 220 , the second intermediate portion 230 being arranged close to the first outer surface 135 or having a surface forming the first outer surface 135 .

[0078] In an example, the second intermediate portion 230 is incompressible or rigid. It is understood that the second intermediate portion 230 is less compressible or more rigid relative to the first intermediate portion, relative to the core 110 and / or relative to the outer layer 120.

[0079] In an example, second intermediate portion 230 has an outer surface defining a shape corresponding to a desired interior shape of at least a portion of the hollow composite member.

[0080] Thus, the second intermediate portion 230 enables the pressure on the first inner region of the ply to be intensified.

[0081] In an example, there may be a plurality of first reinforcement components 130. In an example, the first reinforcement component 130 and at least one additional reinforcement component are arranged at corresponding positions. In an example, the at least one additional reinforcement component may be according to the embodiments and examples of the first reinforcement component 130 as described herein.

[0082] Some further description is provided below, which can be referred to Figure 6 Come to understand.

[0083] According to an embodiment, the core 110 comprises closed-cell foam, and / or wherein the outer layer 120 comprises open-cell foam.

[0084] The second material of the outer layer 120 can be a foam material, such as an open-cell foam. The second material is more compressible than the first material.

[0085] The second material may have a lower density than the first material.The second material may be less rigid than the first material.

[0086] The second material may be at least one of: a polymer, a rubber, a polyurethane, a reticulated polyurethane, PVC, a nitrile, an EPDM; having a density of at least 1 lb / ft3, preferably at least 2 lb / ft3; having a density of at most 4 lb / ft3, preferably at most 3 lb / ft3; as a specific example: or Foam.

[0087] In an example, there can be multiple outer layers 120. In an example, the outer layer 120 and at least one additional outer layer are arranged in corresponding positions. In an example, the at least one additional outer layer can be according to the embodiments and examples of the outer layer 120 as described herein.

[0088] The core 110 can be understood as a support (or base) for the outer layer 120 and / or the first reinforcement component 130. In an example, the outer layer 120 and / or the first reinforcement component 130 are arranged radially outside the core 110. In an example, the outer layer 120 and / or the first reinforcement component 130 are arranged on the core 110.

[0089] In an example, the outer layer 120 and / or the first reinforcement component 130 are bonded to the core 110, for example, using a rubber adhesive. In an example, the outer layer 120 and the first reinforcement component 130 are bonded to each other, for example, using a rubber adhesive.

[0090] Some further description is provided below, which can be referred to Figure 7 Come to understand.

[0091] It will be appreciated that the first reinforcement component 130 is configured to reinforce the pressure on the first interior region of the layup.

[0092] For example, the first reinforcement component 130 is at least partially arranged radially outside the core.For example, the first reinforcement component 130 has an inner radial position within the radial extent of the core.

[0093] In an example, the first reinforcement member 130 is arranged to extend from a radial position within the radial range of the core, or from an outer surface of the core 110 .

[0094] Thus, the core acts as a constraint to control the direction of the force exerted by the first reinforcement component 130 on the layup (the first interior region of the layup).

[0095] According to an embodiment, the outer skin portion 260 of the first reinforcement component 130 forming the first outer surface 135 is more rigid than the first middle portion 220 of the first reinforcement component 130 .

[0096] According to an embodiment, the skin portion 260 of the first reinforcement component 130 forming the first exterior surface 135 is more rigid than the portion of the outer layer 120 forming the second exterior surface 125 of the outer layer 120 .

[0097] In an example, the skin portion 260 has a modulus of rigidity that is at least an order of magnitude greater than the modulus of rigidity of the first intermediate portion 220 , the core 110 , and / or the outer layer 120 .

[0098] In an example, the skin portion 260 is made of a rigid material, such as fiber reinforced plastic. In an example, the skin portion 260 is incompressible or rigid.

[0099] In an example, skin portion 260 has an outer surface that defines a shape that corresponds to a desired interior shape of at least a portion of the hollow composite member.

[0100] Thus, the skin portion 260 achieves a pressure reinforcement on the first interior region of the layup.

[0101] According to an embodiment, the first outer surface 135 of the first reinforcement component 130 includes features with a radius that is smaller than the radius of any features of the second outer surface 125 of the outer layer 120 .

[0102] In an example, the first outer surface 135 of the first reinforcement component 130 is a discontinuous surface or a non-planar surface.

[0103] As a result, the mandrel's performance is improved with respect to the desired shape of a hollow composite component having defined features (e.g., features with small radii, such as corners). Consequently, the desired shape of the hollow composite component can be better achieved. Consequently, undesirable effects such as bridging can be better avoided.

[0104] In the example, the first rigid surface portion 240 is arranged on the radially proximal side of the hollow portion 210. In the example, the second rigid surface portion 250 is arranged on the radially distal side of the hollow portion 210.

[0105] Thus, the first rigid surface portion 240 and the second rigid surface portion 250 enable a directed transfer of pressure reinforcement onto the first inner region of the ply.

[0106] The term "radially proximal" may be understood as being closer to the center (of the core 110) in the radial direction, or closer to the core 110 in the radial direction. The term "radially distal" may be understood as being farther from the center (of the core 110) in the radial direction, or farther from the core 110 in the radial direction.

[0107] The term “radial direction” may be understood as a direction extending outward from the center of the core 110 or the center of the mandrel on a cross-sectional plane of the core 110 or a cross-sectional plane of the mandrel.

[0108] The term “radially” may be understood as a direction extending outward from the center of the core 110 or from the center of the mandrel in a cross-sectional plane of the core 110 or a cross-sectional plane of the mandrel.

[0109] According to embodiments, the thickness of outer layer 120 is dimensioned to enable removal of the mandrel from the hollow composite member and / or wherein the thickness of outer layer 120 is dimensioned based on the compressibility of the second material of outer layer 120 and the geometry of the hollow composite member.

[0110] Thus, the compressed mandrel having a reduced cross-sectional size (particularly due to the compression of the outer layer 120) can be removed from the hollow composite structure for post-curing. It will be appreciated that when the mandrel is not compressed, i.e., when the mandrel is in a non-compressed state, the mandrel cannot be removed from the hollow composite structure for post-curing.

[0111] Thus, as described herein, a compressible mandrel may be understood as one that enables the mandrel to be removed from the hollow composite member for post-curing. Since compressible mandrels are particularly at risk of producing undesirable effects (such as bridging) due to their compressibility, a compressible mandrel provided with a pressure reinforcement member as described herein enables the compressible mandrel to achieve shape definition similar to a rigid mandrel, but still having the advantages of a compressible mandrel.

[0112] According to one aspect, there is provided a method for producing a hollow composite component for a wind turbine rotor blade using a mandrel as described herein, the method comprising placing layups in a mold around the mandrel and performing an in-mold curing process.

[0113] Some further description is provided below, which can be referred to Figure 8 Come to understand.

[0114] Placing the plies around the mandrel in the mold 1110 can be understood as a fiber material layup process. In an example, the plies are laid in the mold or in a portion of the mold. In an example, the mandrel is placed on the laid plies. In an example, the laid plies are placed around the mandrel with the mandrel placed on top.

[0115] The in-mold curing process 1120 may be understood as following a resin infusion process. It is understood that the resin infusion process is performed after vacuuming the mold.

[0116] Some further description is provided below, which can be referred to Figure 9 Come to understand.

[0117] According to an embodiment, the method for producing a hollow composite component for a wind turbine rotor blade comprises activating the first reinforcement part 1210 at least during the in-mold curing process, preferably before the in-mold curing process.

[0118] According to an embodiment, activating the first reinforcement component 1210 includes pressurizing a hollow portion of the first reinforcement component with a fluid.

[0119] In an example, a gas or liquid pump can be fluidly connected to the hollow portion 210. In an example, the hollow portion can be pressurized using a gas or liquid pump.

[0120] In an example, fluid pressurizing the hollow portion of the first reinforcement component includes pumping gas or liquid into the hollow portion of the first reinforcement component. In an example, when the pressure of the fluid in the hollow portion reaches an upper limit pressure of the hollow portion, the hollow portion is in a fluid pressurized state or an expanded state.

[0121] According to an embodiment, a method for producing a hollow composite component for a wind turbine rotor blade includes removing a mandrel 1240 from the composite component.

[0122] According to an embodiment, removing the mandrel 1240 includes deactivating the first reinforcement component 1220 and pulling a vacuum 1230 on the mandrel.

[0123] According to an embodiment, deactivating the first reinforcement component 1220 includes releasing fluid pressure to the first reinforcement component after the in-mold curing process.

[0124] According to an embodiment, activating the first reinforcement component 1210 includes applying a first pressure on a first interior region of the layup through the first reinforcement component that is higher than a second pressure applied by the outer layer on a second interior region of the layup adjacent to the first interior region.

[0125] Thus, at least during the curing of the layup, the pressure is intensified. As a result, the desired shape of the hollow composite component can be better achieved.

[0126] According to one aspect, there is provided a hollow composite component for a wind turbine rotor blade manufactured using a mandrel as described herein.

[0127] Some further description is provided below, which can be referred to Figure 10 and Figure 11 Come to understand.

[0128] In an example, the hollow composite member of a wind turbine rotor blade as described herein is a spar cross member (eg, a portion thereof), such as the first spar component 510 or the third spar component 610 .

[0129] In one example, the first spar member 510 is a hollow spar member that is integrally incorporated into the structure of the wind turbine rotor blade 530. In another example, the first spar member 510 is constructed from a plurality of members including at least one hollow composite member.

[0130] In an example, the third spar member 610 is a hollow spar member disposed within a receiving section (eg, the first spar member 510 ) of the wind turbine rotor blade 530 .

[0131] In an example, the second spar member 520 may include a hollow composite member, such as a hollow spar web that may be disposed between spar caps.

[0132] In an example, the wind turbine rotor blade 530 may be Figure 10 Painted in.

[0133] As an exemplary embodiment, the core is formed from a harder, less compressible foam. As an exemplary embodiment, the mandrel is cut to the contour of the inner mold line of the hollow composite component, minus an offset for the expanded plies. As an exemplary embodiment, the mandrel is also offset to allow the more compressible open-cell plies to form the outer layers.

[0134] As an exemplary embodiment, the thickness of the outer layer is defined by the amount of compression required to remove the mandrel from the hollow composite member.As an exemplary embodiment, the thickness of the outer layer is based on or in accordance with the geometry of the hollow composite member.

[0135] As an exemplary embodiment, the compressible member is disposed in an area of ​​the ply where higher compression is desired. As an exemplary embodiment, the compressible member may have a constrained shape when compressed, or its movement may be constrained to a specific direction, ie, provide a force vector.

[0136] As an illustrative example, the core is used to control and direct the force vector to a desired location on the ply.

[0137] As an exemplary embodiment, the outer layer is compressible.As an exemplary embodiment, by removing air from the mandrel, the foam is compressed and the mandrel size is reduced to allow the mandrel to be removed from the hollow composite member, where it would otherwise be locked by the mold.

[0138] As an exemplary embodiment, the less compressible member constitutes the core of the mandrel. As an exemplary embodiment, the core acts as a support for the compressible layers and a constraint that controls the direction in which the compressive forces are applied to the layup.

[0139] As an exemplary embodiment, the grooves in the core are oriented in the direction in which pressure is applied to the laminate. As an exemplary embodiment, the grooves in the core act as cylinder walls.

[0140] As an exemplary embodiment, the slots in the core are filled with expandable elements that provide directional movement and / or pressure. As an exemplary embodiment, the expandable elements are covered with a harder and / or less compressible foam, or even a solid rigid member if necessary to precisely locate the area where compression is required.

[0141] As an illustrative example, the outer layer is made of a compressible open-cell material that can be significantly reduced in size under compression or vacuum, thereby allowing the mandrel to be removed from the shape it was locked into by the mold.

[0142] As an exemplary embodiment, the mandrel includes foams of different hardnesses. As an exemplary embodiment, a first foam is provided for all-around coverage, and a second foam that is firmer than the first foam is provided for the corners.

[0143] As an illustrative example, a combination of open-cell foam and closed-cell foam is provided for the corners.

[0144] It would be beneficial to provide a mandrel design that allows for the manufacture of hollow mold-locked composite parts. A collapsible mandrel advantageously facilitates removal. A mandrel incorporating reinforcements that are pneumatically activated and provide controlled linear movement to reinforce pressure in specific areas, such as corners or other geometries requiring well-defined shapes, would be beneficial.

[0145] It is beneficial to use closed cell foams of various densities and compressibilities, open cell foams of various densities and compressibilities, composite rigid members, and inflatable / expandable members that are constrained in a manner that controls the direction of movement to provide pressure.

[0146] It would be beneficial to provide a pressurized mandrel shape that is constrained and controlled in a manner that defines its final shape. This final shape can be achieved using internal and external reinforcements such as drop stitches, continuous fibers, and fabrics.

[0147] Beneficially, the highly directional movement ensures that critical areas of the part are well defined while still allowing sufficient collapsibility or compressibility to permit removal of the mold locked part.

[0148] It would therefore be beneficial to combine the ability to apply pressure to specific areas of a part while still having sufficient compressibility to allow removal from a hollow mold lock composite structure. Generally speaking, in a compressible mandrel, the expansion is uniform.

[0149] It is beneficial to control the location where pressure is applied to avoid bridging of the glass fabric. Generally speaking, the inflatable does not restrict expansion. Therefore, a mandrel is provided that precisely controls the location where pressure is applied while still being able to collapse sufficiently to offset mold locking and allow removal.

[0150] Thus, a mandrel is described that allows for constraining expansion in specific directions through the use of different compressibility members or internal constraints to the expansion structure (such as drop stitch sutures or other reinforcements) to allow for precise control of the axis of applied force.

[0151] We have found that in wing spar beams molded for pin joints in wind turbines, the inner radius is critical to reducing the fatigue resistance of the part. We have found that these radii are mainly controlled by the way the glass is laid. We have found that this is extremely operator dependent.

[0152] This has been found to be one of the most significant causes of component rejection, and repairing the interior of such hollow components is generally practically impossible.

[0153] Thus, a mandrel is described that controls the direction of force through reinforcement. Advantageously, a hollow shape is used that can be pressurized with a gas or liquid, but constrained to a final shape when pressurized. This can be advantageously achieved through internal reinforcements, fabrics, or drop stitch seams that define the final pressurized shape and prevent expansion in directions where compression is not desired or necessary.

[0154] Such mandrels have been found to be more resource efficient than mechanical equipment. Such mandrels have been found to be more flexible due to the small number of solid / rigid components. Such mandrels have been found to require much less precision and are more relaxed in terms of not constraining the axis.

[0155] Solid mandrels with (mechanical) activators to apply pressure in specific areas are generally very complex, less flexible and much less resource efficient.

[0156] This written description uses embodiments and examples to provide an enabling disclosure. The scope of the present invention is defined by the following claims.

Claims

1. A mandrel for producing a hollow composite component for a wind turbine rotor blade, the mandrel comprising: A core (110) of a first material; an outer layer (120) of a second material disposed radially outwardly of the core (110), the second material being more compressible than the first material; as well as a first reinforcement part (130) for reinforcing the pressure on a first inner region of the laminate, said first reinforcement part (130) being arranged at least partially radially outside said core (110), wherein a first outer surface (135) of the first reinforcement component (130) and a second outer surface (125) of the outer layer (120) together form a defined shape corresponding to a desired interior shape of at least a portion of the hollow composite member.

2. The mandrel of claim 1, wherein the first reinforcement member (130) comprises a hollow portion (210) expandable by a pressurized fluid.

3. The mandrel according to claim 2, wherein the hollow portion (210) is arranged close to the core (110) and / or wherein the hollow portion (210) is at least partially surrounded by the core (110).

4. The mandrel according to any one of claims 2 to 3, wherein the hollow portion (210) is fluidly isolated from the core (110) and the remainder of the first reinforcement member (130).

5. The core shaft according to any one of claims 2 to 4, wherein the hollow portion (210) includes at least one of the following groups: a dropped stitch portion (410; 420), continuous fibers and reinforcements to define the shape of the hollow portion (210) in the expanded state (320).

6. A core shaft according to any one of claims 1 to 5, wherein the first reinforcement component (130) includes a first intermediate portion (220) of a third material, which is less compressible than the second material of the outer layer (120), preferably, wherein the first intermediate portion (220) includes a closed-cell foam.

7. The mandrel of claim 6, wherein an outer skin portion (260) of the first reinforcement component (130) forming the first outer surface (135) is more rigid than a middle portion (220) of the first reinforcement component (130); and / or A mandrel according to any one of claims 1 to 6, wherein the skin portion (260) of the first reinforcement component (130) forming the first outer surface (135) is more rigid than the portion of the outer layer (120) forming the second outer surface (125) of the outer layer (120); and / or The mandrel of claim 6, wherein the first reinforcement member (130) includes a second intermediate portion (230) that is less compressible than the first intermediate portion (220), the second intermediate portion (230) being arranged adjacent to the first outer surface (135) or having a surface forming the first outer surface (135).

8. The mandrel according to any one of claims 1 to 7, wherein the first outer surface (135) of the first reinforcement component (130) includes a feature having a radius that is smaller than the radius of any feature of the second outer surface (125) of the outer layer (120).

9. The mandrel according to any one of claims 1 to 8, wherein the core (110) comprises a closed-cell foam, and / or wherein the outer layer (120) comprises an open-cell foam.

10. The mandrel according to any one of claims 1 to 9, wherein the thickness dimension of the outer layer (120) is configured to enable the mandrel to be removed from the hollow composite component, and / or wherein the thickness dimension of the outer layer (120) is configured based on the compressibility of the second material of the outer layer (120) and the geometric shape of the hollow composite component.

11. A method for producing a hollow composite component for a wind turbine rotor blade using a mandrel according to any one of claims 1 to 9, the method comprising: placing the layup in a mold around the mandrel (1110); as well as An in-mold curing process is performed (1120).

12. The method according to claim 11, further comprising: activating the first reinforcement component (1210) at least during the in-mold curing process, preferably before the in-mold curing process, Preferably, activating the first reinforcement component (1210) comprises pressurizing a hollow portion of the first reinforcement component with a fluid.

13. The method according to any one of claims 11 to 12, further comprising: removing the mandrel (1240) from the composite component, wherein removing the mandrel (1240) includes deactivating the first reinforcement component (1220) and drawing a vacuum (1230) on the mandrel, Wherein deactivating the first reinforcement component (1220) preferably includes releasing fluid pressure to the first reinforcement component after the in-mold curing process.

14. The method according to any one of claims 11 to 13, wherein activating the first reinforcement component (1210) includes applying a first pressure on a first inner region of the laminate through the first reinforcement component, the first pressure being higher than a second pressure applied by the outer layer to a second inner region of the laminate near the first inner region.

15. A hollow composite component for a wind turbine rotor blade manufactured using a mandrel according to any one of claims 1 to 9.

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