A pre-formed root-end component for a wind turbine blade and method and apparatus for manufacturing a pre-formed root-end component for a wind turbine blade

Abstract

Method for manufacturing a pre-formed root-end component (10) for a wind turbine blade, the method comprises steps of: - providing a continuous root-end sequence, the continuous root-end sequence comprises repeats of two successive bushings (110) followed by a core (120) arranged along a process direction (X); - wrapping a first layer (210) comprising one or more layers of reinforcement material around the continuous root-end sequence, thereby forming a wrapped continuous root-end sequence; and either - embedding the wrapped continuous root-end sequence in a second layer (310) comprising roving with a binding agent, thereby forming an embedded continuous root-end sequence; and - passing the embedded continuous root-end sequence through a heated die (1500) along the process direction (X) to consolidate the roving and binding agent into a pre-formed continuous root-end sequence (400), or - embedding the wrapped continuous root-end sequence in a second layer (310) comprising roving; thereby forming an embedded continuous root-end sequence; - wrapping a third layer (610) comprising one or more layers of reinforcement material with a binding agent around the embedded continuous root-end sequence, thereby forming a covered continuous root-end sequence (610); - passing the covered continuous root-end sequence through a heated die (1500) along the process direction (X) to consolidate the third layer (610) into a pre-formed continuous root-end sequence (400).

Description

[0001] A pre-formed root-end component for a wind turbine blade and method and apparatus for manufacturing a pre-formed root-end component for a wind turbine blade

[0002] Field of the Invention

[0003] The present invention relates to a method and apparatus for manufacturing a pre-formed root-end component for a wind turbine blade.

[0004] The present invention further relates to a pre-formed root-end component for a wind turbine blade, a wind turbine blade, and method for manufacturing a wind turbine blade.

[0005] The present invention furthermore relates to a continuous strand, a continuous root-end sequence, a wrapped continuous root-end sequence, an embedded continuous root-end sequence, a covered continuous root-end sequence, and a pre-formed continuous rootend sequence for manufacturing a root-end component for a wind turbine blade.

[0006] Background of the Invention

[0007] Wind turbine blades are typically made from a fibre-reinforced polymer and constituting of two blade shell halves, which are manufactured in blade moulds. In a typical manufacturing process, fibre reinforcements and / or fabrics are placed in the blade moulds followed by a vacuum infusion of resin into the fibre reinforcements and / or fabrics, whereafter the blade shell halves are glued or bolted together to form a wind turbine blade.

[0008] The wind turbine blades are typically fastened to a hub to form a rotor of the wind turbine using bolts or threaded rods connected to bushing embedded in the root region of the wind turbine blade. The bushings are usually cylindrical and made of metal, such as steel. Due to the mass of the wind turbine blade and wind forces, significant stress is put on the blade -hub connection. It is, therefore, critical that the blade-hub connection can transfer the heavy load from the blade to the hub, and the way of which the bushings are embedded into the root region of the wind turbine blade thus becomes critical.

[0009] Currently, the metal bushings are in between fibre layers of the wind turbine root region, and separate fibre -reinforced inserts are placed between adjacent bushings. However, this is associated with weak interfaces between the fibre-reinforced inserts and the metal bushings, where the metal bushings are insufficiently retained in the fibre-reinforced material of the wind turbine blade and is at risk of being pulled out of the fibre reinforced material in the root region.

[0010] Efforts have also been made to provide pre-formed fibre-reinforced inserts containing the bushing, thereby, only bushing containing inserts are placed adjacent to one another in the root region of the wind turbine blade. However, this is associated with an inefficient, time consuming, and expensive manufacturing process, as each insertion element must be manufactured individually with a manual moulding operation.

[0011] There is therefore a need for pre-formed inserts containing bushing, which can be manufactured effectively and automatically.

[0012] Object of the Invention

[0013] It is an objective of the present invention to provide a method and apparatus which continuously and automatically can manufacture pre-formed root-end component for a wind turbine blade, thereby providing a more effective and cost-efficient manufacturing process for manufacturing pre-formed root-end components.

[0014] It is a further objective of the present invention to provide a pre-formed root-end component for a wind turbine blade, a wind turbine blade, and method for manufacturing a wind turbine blade with strong retainment of bushing embedded in the reinforcement material, thereby providing a strong blade-hub connection for transferring the heavy load from the wind turbine blade.

[0015] It is a further objective of the present invention to provide a continuous strand, a continuous root-end sequence, a wrapped continuous root-end sequence, an embedded continuous root-end sequence, and a pre-formed continuous root-end sequence for manufacturing a root-end component for a wind turbine blade, thereby providing a more effective and cost-efficient manufacture of pre-formed root-end components.

[0016] Description of the Invention

[0017] An objective of the present invention is achieved by a method for manufacturing a preformed root-end component for a wind turbine blade. The method comprises steps of: providing a continuous root-end sequence, the continuous root-end sequence comprises repeats of two successive bushings followed by a core arranged along a process direction; wrapping a first layer comprising one or more layers of reinforcement material around the continuous root-end sequence, thereby forming a wrapped continuous root-end sequence; and either embedding the wrapped continuous root-end sequence in a second layer comprising roving with a binding agent, thereby forming an embedded continuous root-end sequence; and passing the embedded continuous root-end sequence through a heated die along the process direction to consolidate the roving and binding agent into a preformed continuous root-end sequence or embedding the wrapped continuous root-end sequence in a second layer comprising roving; thereby forming an embedded continuous root-end sequence; wrapping a third layer comprising one or more layers of reinforcement material with a binding agent around the embedded continuous root-end sequence, thereby forming a covered continuous root-end sequence; and passing the covered continuous root-end sequence through a heated die along the process direction to consolidate the third layer into a pre-formed continuous root-end sequence.

[0018] Thereby providing a method for continuously producing pre-formed root-end components for a wind turbine blade. The method enables that pre-formed root-end components for a wind turbine blade can be manufactured in plurality, where the method further may be an automated manufacturing method, thereby providing effective and costefficient continuous production of pre-formed root-end components.

[0019] The method further provides pre-formed root-end components for utilization in a root region of wind turbine blade for connecting the wind turbine blade with a hub, which significantly reduces the number of bonding interfaces in the root region, thereby significantly increasing the fatigue-resistance of the root region capable of withstanding the loads from the wind turbine blade on the blade-hub connection. Furthermore, the method manufactures pre-formed root-end components with embedded bushing, thereby providing a stronger bonding of the bushing to the fibre material surrounding the bushing and, thus, a fatigue-resistant interface between the bushing and the fibre material. The method, therefore, result in considerable structural improvements of the pre-formed root-end components, increasing the pull -resistance of and providing considerable stronger connections to bushings in the root region of the wind turbine blade.

[0020] The method is thus advantageous over prior manufacturing methods, as the method of the present invention circumvents the need for manufacturing and manually pre-forming the root-end components comprising a bushing and / or the need for separate reinforcement inserts arranged between adjacent bushings and embedded in the root region of the wind turbine blade, which is associated with a weak binding interface between bushings, the reinforcement inserts and the blade shell. The weak binding interface with the bushing in prior art solutions carry a great risk of the bushings being pulled out, when the blade -hub connections experience the heavy loads of the wind turbine blade. Furthermore, the prior art solution for manufacturing pre-formed reinforcement structures comprising the bushings is inefficient and associated with high production costs, because the component must be produced one at the time, and due to the need for a manual step of pre-forming the structure. In comparison, the method of the present invention is cost effective, fast, and efficient, because a plurality of pre-formed rootend components can be produced in a completely automated manufacturing process and in one continuous strand of a pre-formed continuous root-end sequence, during one production run, which can be cut into separate pre-formed root-end components that can be directly mounted in the root region of the blade shell mould. In the blade shell mould the separate pre-formed root-end components can be co-infused with the blade shell materials like glass fabrics e.g.

[0021] In the following, the term “fabric” denotes any fabric or fibre suitable for manufacturing fibre-reinforced polymers (also known as composites). The term “fabric” is therefore interchangeable with the term “fibre”. The term “reinforcement material” denotes any fibre-reinforced material, which may be multi layered fabrics, multi layered roving, multi layered tows, multi layered ropes, or any other fibre-reinforced materials. The term “roving” denotes any long and narrow bundle of fibre. The term “a binding agent” denotes one binding agent or a combination of binding agents, such as polymers. Thus, the term “a binding agent” should be understood as one or more binding agents, and the same applies for the definite form “the binding agent”. The term “pre-form” or “preformed” denotes a consolidated fibre -reinforced materials prior to being impregnated with a resin matrix to form a composite material. The term “elongate” refers to a component having a length which is greater than both its width and thickness. These interpretations apply throughout the specification.

[0022] In the following, the mentioned glass fibre materials could be any of the commercially available material such as E (electric) glass, ECR (E-glass corrosion resistant) glass, H (high modulus) glass or UHM (ultra high modulus) glass, or any combination thereof.

[0023] In the following, the bushings may be elongate bushing extending along an axis parallel to the process direction. In an embodiment, the bushings may comprise a first receiving end configured for receiving a bolt or threaded rod on a hub, a second end, and a body region extending between the first receiving end and the second end. The bushings may further comprise an internal threaded bore extending from an opening in the first receiving end towards the second end inside the body region. The exterior surface of the body region may optionally comprise circumferential grooves, thereby providing greater friction, stronger binding interface and, thus, a greater pull resistance between the bushings and the first layer of reinforcement material. Optionally, the bushing may have a substantially cylindrical exterior surface. However, it should be noted that the method of the present invention is not dependent on the bushing design, thus, any bushing with any bushing design suitable for engaging in a blade-hub connection may be utilized for the present invention.

[0024] In an embodiment, the two successive bushings are metal bushings. Preferably steel bushings.

[0025] In another embodiment, the two successive bushings are conical bushings. The conical bushings improve the pull-out strength and resistance against fatigue failure or relaxation leading to repeated maintenance where the bolts require pre-tensioning.

[0026] The core may be an elongate core extending along an axis parallel to the process direction and may be fibrous. In an embodiment, the core is made of a glass fibre reinforced polymer or a thermoplastic foam or unidirectional (UD) fabric or UD roving or texturized glass roving or texturized glass fabric or a preform of any of these. The preforms are advantageous, as a resin matrix may infuse into the core during a resin infusion of a pre-formed root-end component, thereby, providing a stronger binding between the interfaces in the pre-formed root-end component. In an embodiment, the core and the two successive bushings may have the same diameter, and optionally, the core may have a substantially cylindrical exterior surface, thereby providing a continuous root-end sequence with a constant diameter.

[0027] In the step of providing the continuous root-end sequence, the two successive bushing may be arranged with their respective first receiving ends facing each other, thereby having their second ends facing an end of a core. By cutting between the two successive bushing and through the core in the pre-formed root-end sequence, pre-formed root-end components have a first end comprising the opening of the first receiving end of the bushing, and a second end comprising the core. Thus, the first end of the pre-formed root-end component is configured for receiving a threaded rod or bolt in a blade -hub connection.

[0028] In an embodiment, a spacer may be provided between the two successive bushings. The spacer enables localization and identification of a cutting line between the two successive bushings, thereby preventing cutting into the bushings during a step of cutting. The spacer may further function as a seal of the opening of the bushings, thereby preventing any resin, binding agent, adhesive or glue from leaking inside the bore of the bushing through the opening during the manufacturing process or a subsequent resin infusion process.

[0029] By providing a continuous root-end sequence comprising repeats of two successive bushings followed by a core arranged along a process direction, manufacture of a plurality of pre-formed root-end components is enabled with the method of the present invention, because a simple cutting procedure of the finished pre-formed continuous root-end sequence provides a plurality of identical pre-formed root-end components.

[0030] In the step of wrapping, the first layer of one or more layers of reinforcement material surrounds the repeats of two successive bushings and core in the continuous root-end sequence, thereby anchoring the first layer to the surface of the continuous root-end sequence. The first layer may be wrapped around the continuous root-end sequence along the process direction. In embodiments, where the exterior surface of the bushings comprises grooves, the first layer of reinforcement material may be anchored into the grooves, thereby increasing the friction between the exterior surface of the bushings and the first layer for a more firmly anchoring of the first layer to the exterior surface of the bushings.

[0031] The first layer further provides a fatigue-resistant interface between the continuous rootend sequence and the second layer of roving with a fatigue strength capable of withstanding the loads on the blade-hub connection, thereby firmly anchoring the bushing and the core within the pre-formed root-end component. Furthermore, the first layer may be applied without a binding agent or an adhesive and may be infused with resin in a later resin infusion process, thereby bonding the first layer to the continuous rootend sequence and fixating the first layer in the resulting root-end component or root region of a wind turbine blade. The first layer thereby serves to firmly anchor the bushing within the pre-formed root-end component.

[0032] Preferably, when wrapped around the continuous root-end sequence, the material of first layer, forms corrugations on the surface of the wrapped continuous root-end sequence. The corrugations increase the friction between the first and second layer, thereby providing a fatigue-resistant interface between the first and second layer with an increased fatigue strength capable of withstanding the loads on the blade -hub connection. Thus, the corrugations prevent or at least reduced the risk of the first and second layer from being pulled from each other, when experiencing the load from the wind turbine blade. The corrugations may naturally occur in during the step of wrapping due to the wrapping process and / or the nature of the reinforcement material, and / or the corrugations may in an embodiment result from the first layer being anchored into the grooves on the exterior surface of the bushings. Furthermore, the corrugations increase the surface area between first and second layers, yielding a higher potential for a strong bond between the first and second layer.

[0033] In an embodiment, the reinforcement material is fabrics or roving or mats, and wherein the fabrics, roving, or mats are made of glass, fibreglass, carbon, carbon fibres, UD glass, or texturized glass. The reinforcement material may further be bundles of filaments or tows of filamentary material of any of the above-mentioned materials.

[0034] The reinforcement material may furthermore be aramid, basalt, paper, wood, boron, asbestos, or any combination thereof.

[0035] In an aspect, the step of wrapping the first layer may comprise

[0036] - a step of winding filamentary reinforcement material around the continuous root-end sequence, or

[0037] - a step of folding fabrics or mats of reinforcement material around the continuous root-end sequence, and / or wherein the second step of wrapping the third layer comprises:

[0038] - a step of winding filamentary reinforcement material around the embedded continuous root-end sequence, or

[0039] - a step of folding fabrics or mats of reinforcement material around the embedded continuous root-end sequence.

[0040] In the step of winding filamentary reinforcement material, the reinforcement material may be wound around the continuous root-end sequence or the embedded continuous root-end sequence. The reinforcement material may be wound around the continuous root-end sequence or the embedded continuous root-end sequence along the process direction. Thereby, the reinforcement material is laid in geometric pattern to create a structural surface of the wrapped continuous root-end sequence or the covered continuous root-end sequence providing a fatigue-resistant interface between the first and second layer or the second and third layer, respectively. There may further be formed corrugations in the resulting surface of the wrapped continuous root-end sequence or the covered continuous root-end sequence. In an embodiment, the continuous root-end sequence or the embedded continuous root-end sequence may rotate during the step of winding.

[0041] In a preferred embodiment, the filamentary reinforcement material may be a UD roving or texturized roving. In the step of folding, the fabrics or mats may be folded around the continuous root end sequence or the embedded continuous root-end sequence. Thereby the reinforcement material may form corrugations on the surface of the wrapped continuous root-end sequence or the covered continuous root-end sequence due to natural wrinkle formation in the fabrics or mats during folding providing a fatigue-resistant interface between the first and second layer or the second and third layer, respectively.

[0042] In a preferred embodiment, the fabrics or fabric mats are made of UD fabrics or texturized fabrics.

[0043] In an embodiment, the filamentary reinforcement material is narrow reinforcement material stripes having a width of 2-10 cm. Thereby, the step of filament winding may be carried out with narrow fabric stripes or fabric mat striped of 1-10 cm in width.

[0044] In an aspect, the method may comprise a step of applying adhesive or glue to an exterior surface of the two successive bushings before and / or after the step of providing or applying adhesive or glue to the reinforcement material of the first layer before the first step of wrapping.

[0045] When the adhesive or glue is applied to the bushing, the adhesive or glue should cover the entire exterior surface of the bushing and impregnate into the first layer, however it should not pass through the first layer and infuse into the second layer. Thereby the first layer is partly adhered to the bushing, while still allowing the first layer to be infused with resin with the rest of the pre-formed root-end sequence or component during a subsequent step of resin infusion. The adhesive may also be applied to an exterior surface of the core. The adhesive layer thus strongly anchors the first layer to the exterior surface of the bushings in the continuous root-end sequence, providing a fatigue-resistant interface between the first layer and bushings.

[0046] When the adhesive or glue is applied to the reinforcement material, the adhesive layer on the reinforcement material strongly anchors the first layer to the exterior surface of the bushings in the continuous root-end sequence, providing a fatigue-resistant interface between the first layer and bushings. The adhesive layer, therefore, prevents that the bushing being insufficiently retained in the fibre-reinforced material of the pre-formed root end component and, thus, in root region of the wind turbine blade, thereby preventing or at least significantly reducing the risk of the bushing being pulled out of the fibre -reinforced material in the root region by the loads from the wind turbine blade.

[0047] In an embodiment, the adhesive or glue is applied with an adhesive layer thickness of 0.5-10 mm or preferably 2-5 mm. The adhesive layer thickness may further be 0.1-5 mm or 0.1-0.5 mm or preferably 0.2-0.4 mm or more preferably about 0.3 mm. In an embodiment, the glue is SikaPower®-1200 with an adhesive layer thickness of about 0.3 mm. However, the invention is not limited to this specific glue, and other adhesives or glues are also applicable. The adhesive layer thickness is measured after application of adhesive on the continuous root-end sequence and before the step of wrapping.

[0048] In the step of embedding, the wrapped continuous root-end sequence is embedded in a second layer comprising roving with a binding agent. The step of embedding is followed by the step of passing the embedded continuous root-end sequence through a heated die may be a pultrusion-like process, wherein the second layer of roving impregnated with binding agent surrounding the wrapped root-end component forms an embedded continuous root-end sequence, which is subsequently passed through the heated die to consolidate the roving and binding agent to a preform.

[0049] In another step of embedding, the wrapped continuous root-end sequence is embedded in a second layer comprising roving without a binding agent, where the step of embedding is followed by the second step of wrapping the embedded continuous root-end sequence in a third layer comprising one or more layers of reinforcement material with a binding agent, thereby providing a covered continuous root-end sequence. The second step of wrapping is followed by the step of passing the covered continuous root-end sequence through a heated die. The step of passing the covered continuous root-end sequence may be a pultrusion-like process, wherein the third layer of one or more layers of reinforcement material impregnated with a binding agent surrounding the embedded root-end component is consolidated into a pre-formed continuous root-end sequence in the heated die. This embodiment is advantageous because the second layer of roving is not consolidated, and the second layer of roving is flexible, thereby providing flexibility to the pre-formed continuous root-end sequence. This may ease the assembling of preformed root-end components in the blade shell mould.

[0050] The wrapped continuous root-end sequence is embedded in a second layer of roving having a thickness filling out the space in the heated die or optionally a preforming die, wherein the second layer is shaped or moulded to a cross-sectional geometry corresponding to the cross-sectional geometry of the heated die or optionally the preforming die, thereby providing the embedded root-end sequence and, thus, the resulting preformed root-end component with a desired cross-sectional geometry suitable for being arranged in a root region of a wind turbine blade. Alternatively, the third layer of reinforcement material has a thickness filling out the space in the heated die or, optionally, a preforming die, wherein the third layer and the underlying second layer is shaped or moulded to a cross-sectional geometry corresponding to the cross-sectional geometry of the heated die or optionally the preforming die.

[0051] The step of embedding may be a step of embedding the wrapped continuous root-end sequence in a second layer along the process direction.

[0052] In an embodiment, the method comprises a step of applying binding agent to the roving prior to the step of embedding, thereby impregnating the roving with a binding agent. In another embodiment, the roving may be off-the-shelf roving supplied with a binding agent, or the roving may be off-the-shelf roving supplied with a binding agent and applied an additional binding agent prior to the step of embedding. Thereby, increasing the degree of consolidation of the roving and binding agent occurring when passing through the heated die. In another embodiment, the method comprises a step of applying binding agent to the one or more layers of reinforcement material of the third layer prior to the second step of wrapping, thereby impregnating the reinforcement material with a binding agent. The reinforcement material may be off-the-shelf reinforcement material supplied with a binding agent, or the reinforcement material may be off-the-shelf reinforcement material supplied with a binding agent and applied an additional binding agent prior to the second step of wrapping. Thereby, increasing the degree of consolidation of the third layer occurring when passing through the heated die. The binding agent may be sprayed onto the surface of the roving to obtain an even distribution of binding agent on the roving surface, thereby reducing the amount of binding agent needed for consolidating the roving and binding agent. The binding agent may be sprayed onto the surface of the reinforcement material to obtain an even distribution of binding agent on surface of the reinforcement material, thereby reducing the amount of binding agent needed for consolidating the third layer.

[0053] In an embodiment, the second layer of roving with a binding agent or without binding agent is UD glass roving and / or texturized glass roving.

[0054] In an embodiment, the binding agent is a thermosetting polymer, a thermoplastic polymer, an adhesive, epoxy resin, vinyl ester, a polyester thermosetting resin, phenol formaldehyde resin, a thermoplastic powder binder, a thermoplastic resin, a thermoplastic resin system, or any combination thereof. Preferably the polymer is a thermoplastic powder binder and / or an adhesive and / or an epoxy resin. The thermoplastic resin system may be a thermoplastic resin sold under the trademark name Elium® or any other recyclable thermoplastic resin system.

[0055] In an embodiment, the roving comprises 1 to 10% or 1 to 7% or preferably 1 to 5% binding agent or the third layer of one or more layers of reinforcement material comprises 1 to 10% or 1 to 7% or preferably 1 to 5% binding agent. Thereby applying a sufficient amount of binding agent to the roving or the reinforcement material, for consolidating the roving or reinforcement material and binding agent to a stiffness and curing degree that enables running a resin infusion of the pre-formed root-end component or pre-formed continuous root-end sequence without the need of a mould.

[0056] In the step of passing, the embedded continuous root-end sequence or the covered continuous root-end sequence is passed through a heated die along the process direction to consolidate the roving and binding agent or the reinforcement material and biding agent of the third layer into a preform, thereby forming a pre-formed continuous root-end sequence. The heated die may encompass a part of the embedded continuous root-end sequence or the covered continuous root-end sequence at a time, thereby heating the encompassed part of the embedded continuous root-end sequence or the covered continuous root-end sequence to consolidate the roving and binding agent or the reinforcement material and biding agent of the third layer contained in the encompassed part into a preform.

[0057] The heated die heats the embedded continuous root-end sequence or the covered continuous root-end sequence to consolidate the roving and binding agent or the reinforcement material and biding agent of the third layer into a preform. Thus, the heated die at least partially melts and / or polymerizes the binding agent to unite the roving or the reinforcement material and binding agent polymer into one preformed fibre-reinforced material. The consolidation of the roving or the reinforcement material and binding agent thus provides a pre-formed continuous root-end sequence with a stiffness and curing degree that is high enough for pre-formed continuous root-end sequence to maintain its shape and low enough for infusing resin into the pre-formed continuous rootend sequence.

[0058] The resulting pre-formed root-end components are, thus, not too rigid, i.e. they are comparatively soft and flexible components that can be easily arranged within a root region of a wind turbine blade.

[0059] The heated die may have a cross-sectional geometry providing the pre-formed continuous root-end sequence and, thus, the resulting pre-formed root-end component with a desired cross-sectional geometry suitable for being arranged in a root region of a wind turbine blade. By passing the embedded continuous root-end sequence or the covered continuous root-end sequence through the heated die the embedded continuous rootend sequence or the covered continuous root-end sequence is compressed and consolidated into the shape of the cross-sectional geometry of the heated die, permanently.

[0060] In an embodiment, the method comprises a step of passing a section of the embedded continuous root-end sequence or the covered continuous root-end sequence through a preforming die prior to the heated die, the preforming die having a pre-determined cross-sectional geometry pre-shaping the section of the embedded continuous root-end sequence to a pre-determined roving cross-sectional geometry or the section of the covered continuous root-end sequence to a pre-determined cross-sectional geometry, thereby pre-shaping the embedded continuous root-end sequence or the covered continuous root-end sequence into the correct shape for easier loading into the heated die. In an embodiment, the embedded continuous root-end sequence or the covered continuous root-end sequence is passed through the heated die by pulling the embedded continuous root-end sequence or the covered continuous root-end sequence through the heated die by a pulling system, thereby providing a pultrusion process for manufacturing pre-formed root-end components.

[0061] In an embodiment, the heated die heats the second layer of roving and binding agent or the third layer of one or more layers of reinforcement material and binding agent to a temperature of 70-180°C or 80-120°C or 90-110°C or preferably about 100°C but is not limited to these temperatures. The temperature required for consolidating the roving and binding agent or the third layer of one or more layers of reinforcement material and binding agent depends on the type of binding agent, the amount of binding agent, the number of roving layers or layers of reinforcement material, and the speed with which the embedded continuous root-end sequence or the covered continuous root-end sequence is passed through the heated die. The temperature should be sufficient for at least partially melting and / or polymerizing the binding agent for consolidating the embedded continuous root-end sequence or the covered continuous root-end sequence into a preform.

[0062] In an embodiment, the embedded continuous root-end sequence or the covered continuous root-end sequence is passed through the heated die at a speed of 4-25 meter per hour or preferably 6-12 meters per hour.

[0063] In an aspect, after the step of passing, the method comprises a step of cutting the preformed continuous root-end sequence along a first cutting line arranged between the two successive bushings and along a second cutting line arranged through the core thereby providing a pre-formed root-end component. Thereby providing two identical pre-formed root-end components comprising a bushing and a core from each repeat of two successive bushings followed by a core in the continuous root-end sequence.

[0064] After cutting the pre-formed continuous root-end sequence along the first cutting line arranged between two successive bushings being arranged head-to-head, one or more pieces of the pre-formed continuous root-end sequence is provided. The one or more pieces of the pre-formed continuous root-end sequence having a first end, a second end, and a body extending between the first and second end, wherein both the first and the second comprises a bushing and the body comprises the core. After cutting the one or more pieces of the pre-formed continuous root-end sequence along the second cutting line arranged through the core two identical pre-formed root end components are provided for each piece of the pre-formed continuous root-end sequence. Thereby providing pre-formed root-end components having a first end comprising a bushing and a second end comprising a core.

[0065] In an embodiment, the step cutting may be a step of cutting along the first and second cutting line simultaneously; or a step of first cutting along the first cutting line followed by a step of second cutting along the second cutting line, vice versa.

[0066] In an embodiment, the first cutting line may be arranged through a spacer provided between the two successive bushings. The spacer, thereby, provides easy identification of the first cutting line between the two successive bushing embedded in a first and second layer, and optionally a third layer. Without the space identification of the first cutting line between the embedded two successive bushings may be difficult Thus, the spacer prevents cutting into the bushings, when cutting along the first cutting line.

[0067] In an embodiment, the first cutting line is perpendicular to the process direction and the second cutting line is angled relative to the process direction, where the angle of the second cutting line relative to the process direction is 2-12 degrees or preferable 3-6 degrees. Thereby providing a pre-formed root-end component having a straight first end perpendicular to the process direction, which is suitable for engaging in a blade hub connection, and a wedged- shaped towards the second end, thereby providing a chamfered pre-formed root-end component. The amount of material in pre-formed root-end component is, thus, reduced, providing a lighter pre-formed root-end component, which is advantageous for use in a wind turbine blade, because a reduced weight of the wind turbine blade reduces the load from the wind turbine blade on the blade-hub connection. The wedged- shaped second end further increases the binding strength of the pre-formed root-end component to the root region of the wind turbine blade. The wedged-shaped second end also improves the joint strength of the pre-formed root-end component to the root region of the wind turbine blade In an embodiment, the pre-formed continuous root-end sequence has a cross-sectional geometry comprising the continuous root-end sequence having a substantially circular cross-sectional geometry surrounded by the first layer having a substantially circular cross-sectional geometry, the first layer being surrounded by a second layer having a cross-sectional geometry being a substantially square shaped or a substantially rectangular shape, cross-sectional geometry, or comprising a first and a second part being displaced relative to each other, or comprising a first part, a second part, and a third part arranged between the first and second part, where the third part is displaced relative to the first and second part.

[0068] Thus, the resulting pre-formed root-end component has cross-sectional geometry identical to that of the pre-formed continuous root-end sequence.

[0069] The first, second and, third parts of the second layer cross-sectional geometry may have a substantially rectangular shaped cross-sectional-geometry.

[0070] A substantially square shaped cross-sectional geometry of the second layer provides an increased interface between the two pre-formed root-end components arranged adjacent to each other in the root region of a wind turbine blade, thereby increasing the boding strength between two adjacent pre-formed root-end components in the interface.

[0071] A second layer having a cross-sectional geometry comprising two or three parts displaced relative to each other further increases the interface between the two pre-formed root-end components arranged adjacent to each other in the root region of a wind turbine blade, thereby further increasing the bonding strength between two adjacent pre-formed root-end components in the interface. The displaced parts furthermore provides a lateral face of the pre-formed root end components which can interlock with a lateral face of an adjacent pre-formed root-end component, thereby interlocking adjacent pre-formed root-end components to each other in the root region for a stronger mounting of the preformed root-end components in the wind turbine blade with a greater pull-resistance, providing a stronger blade -hub connection. The third layer may have the same cross-sectional geometry as the second layer or the second layer may have a substantially circular cross-sectional geometry, where the third layer has a cross-sectional geometry of the second layer according to one of the abovedescribed configurations.

[0072] In an embodiment, the pre-formed continuous root-end sequence has a cross-section size of 6- 18 cm in height and 6-18 cm in width. The cross-section size may be dependent on the size and dimensions of the wind turbine blade.

[0073] The heated die may further be configured for compressing the second layer and / or the third layer to a cross-section size of 6-18 cm in height and 6-18 cm in width. The heated die may further have a die cross-sectional geometry complementary to the cross-sectional geometry of the pre-formed continuous root-end sequence.

[0074] In an aspect, the method may comprise a step of infusing resin into the first layer and second layer, and optionally the core of

[0075] - the pre-formed continuous root-end sequence, or

[0076] - the pre-formed root-end component, or

[0077] - an assembly of pre-formed root-end components arranged in a root region of a blade shell structure.

[0078] In another aspect, the method may comprise a step of infusing resin into the first layer, the second layer, and the third layer, and optionally the core of:

[0079] - the pre-formed continuous root-end sequence, or

[0080] - the pre-formed root-end component, or

[0081] - an assembly of pre-formed root-end components arranged in a root region of a blade shell structure.

[0082] In a preferred embodiment, the step of infusing is a step of infusing resin into the first layer and second layer or the first layer, the second layer, and the third layer, and optionally the core of an assembly of pre-formed root-end components arranged in a root region of a blade shell structure. Thereby, circumventing or at least significantly reducing the number of interfaces in the root region and, thus, preventing weak interfaces in the root region and increasing the fatigue strength of the root-end components arranged in the root region capable of withstanding the loads on the blade -hub connection. This embodiment is further advantageous, as the resin infusion of the assembly of pre-formed root-end components can be run along with the resin infusion of the wind turbine blade mould.

[0083] In an embodiment, the step of infusing may be a vacuum infusion wherein a resin is infused into the second layer and first layer, or the first layer, the second layer, and the third layer, and optionally the core by a vacuum pressure. The vacuum infusion enables a high fibre-to-resin ratio, thereby improving the mechanical properties and obtaining a high mechanical performance of the pre-formed root-end components. Thereby providing a fatigue-resistant interface between the first and second layer, and between the first layer and the bushing and core or between the first and second layer, the second and third layer, and between the first layer and the bushing and core with a fatigue strength capable of withstanding the loads on the blade -hub connection, thereby firmly anchoring the bushing within the pre-formed root-end component and / or in the root region of the wind turbine blade.

[0084] Thus, the amount of binding agent applied to the roving in the second layer or the reinforcement material in the third layer should be sufficient for consolidating the roving or reinforcement material and binding agent to a pre-form with a stiffness and curing degree that is high enough for the pre-form root-end competent to maintain its shape but still low enough to enable a vacuum infusion. A too high amount of binding agent can be problematic for running a vacuum infusion, as the polymerized and / or consolidated binding agent resulting from the passing through the heated die may prevent the resin from being infused into the fibre layers of the pre-form root-end component during the vacuum infusion process.

[0085] In an embodiment, the method comprises a step of sealing an exterior first end of the bushings arranged opposite to the core before the step of infusing, thereby preventing resin from leaking inside a bore of the bushing through an opening in the exterior first end during the resin infusion process. The is advantageous, because the resin may clog the bore, thereby, the bore cannot receive a bolt or a threaded rod from the hub to connect the wind turbine blade to the hub. A second end of the bushing facing the core may automatically be sealed by the core or the fibre material in the pre-formed root-end component.

[0086] In an aspect, at least one bushing comprises one, two, three, or more holes. In a preferred embodiment, the at least one bushing comprises one hole. The holes may be located in the body of the bushing and / or in the second end of the bushing and be in fluid connection with the bore of the bushing. The holes can be utilised for infusing resin into a preformed root-end component or an assembly of pre-formed root-end components arranged in a root region of a blade shell structure, thereby achieving a better distribution of resin within the fibre material of the core, first layer and second layer or the fibre material of the core, the first layer, the second layer, and the third layer of the preformed root-end components, and in the interface between adjacent pre-formed rootend components. This provides a fatigue-resistant interface between the second and third layer, between the first and second layer, between the first layer and the bushing and core, and between adjacent pre-formed root-end components with a fatigue strength capable of withstanding the loads on the blade -hub connection, thereby firmly anchoring the bushing within the pre-formed root-end component and / or in the root region of the wind turbine blade.

[0087] In an embodiment, the pre-formed continuous root-end sequence or preferably the embedded continuous root-end sequence or the covered continuous root-end sequence may be applied an intermediate layer with 20-65% out of plane glass fibre fabric or glass fibre mat, which is arranged one lateral surface or two opposing lateral surfaces of the pre-formed continuous root-end sequence or the embedded continuous root-end sequence or the covered continuous root-end sequence. The intermediate layer may be applied with a binding agent. Thereby, the pre-formed continuous root-end sequence or preferably the embedded continuous root-end sequence or the covered continuous rootend sequence with the intermediate layer with binding agent arranged on two opposing lateral surfaces can then be passed through a heated die to consolidate the intermediate layer and binding agent into a pre-form. The step of passing through the heated die may be a step of passing through the heated die, wherein the second layer of the embedded continuous root-end sequence or the third layer of the covered continuous root-end sequence with the intermediate layer with binding agent arranged on two opposing lateral surfaces or the pre-formed continuous root-end sequence with the intermediate layer with binding agent arranged on two opposing lateral surfaces is consolidated to preform.

[0088] By sticking out of plane is meant that the fibres or part of the fibres extend in a direction which is non-parallel with the two largest surfaces of the fabrics or mats. The fibres or part of the fibres extend in a direction normal to the 2D-plane of the fabrics or mats.

[0089] When arranging pre-formed root-end components having an intermediate layer arranged on one lateral surface or two opposing lateral surfaces in the root region mould for resin infusion, the intermediate layer is arranged between the lateral surfaces of adjacent pre-formed root-end components. Thereby, the intermediate layer creates small pre-formed spacings between adjacent pre-formed root-end components which may subsequently be infused with resin. This provides a stronger bonding of the pre-formed root-end components in the root region.

[0090] In an aspect, the continuous root-end sequence, the wrapped continuous root-end sequence, the embedded continuous root-end sequence, and the pre-formed continuous root-end sequence forms a continuous strand along the process direction, or wherein the continuous root-end sequence, the wrapped continuous root-end sequence, the embedded continuous root-end sequence, the covered continuous root-end sequence, and the pre-formed continuous root-end sequence forms a continuous strand along the process direction, the continuous strand being continuously guided along the process direction or being guided stepwise along the process direction.

[0091] The method may thus be a continuous process, wherein the continuous strand is constantly passed through each method step without stopping, thereby continuously producing the pre-formed continuous root-end sequence or pre-formed root-end components. This streamlines the manufacturing process compared to a stepwise production (see below), where the two or more fabric layers are briefly stopped during each step for a period of time, because less process steps are needed. The continuous process further reduces processing time, and significantly reduces manufacturing costs, because a plurality of pre-formed root-end component can be continuously manufactured. The step of passing may, therefore, be a step of continuously passing the embedded continuous root-end sequence or the covered continuous root-end sequence through the heated die in the process direction, whereby the heated die constantly apply heat to the roving or reinforcement material of the third layer and binding agent while continuously passing the embedded continuous root-end sequence or the covered continuous rootend sequence through the heated die, thereby continuously consolidating the roving or reinforcement material and binding agent into a pre-form.

[0092] The method may, further, be a semi-continuous process, wherein the continuous strand is passed through each method step in a stepwise manner, where a part of the continuous strand is retained for period of time at each method step. Thereby, the continuous strand may run with a higher speed compared to the continuous process. The semi-continuous process, thus, also reduces processing time, and significantly reduces manufacturing costs, because a plurality of pre-formed root-end component can be continuously manufactured.

[0093] The step of passing may, therefore, be a step of stepwise passing the embedded continuous root-end sequence or the covered continuous root-end sequence through the heated die in the process direction, where a part of the embedded continuous root-end sequence or the covered continuous root-end sequence encompassed by the heated die is retained in the heated die for a period of time. Thereby heating a part of the embedded continuous root-end sequence or the covered continuous root-end sequence at the time to consolidate the roving or reinforcement material and binding agent into a pre-form. In this embodiment, the heated die may periodically apply heat to embedded continuous rootend sequence or the covered continuous root-end sequence, thereby only applying heat for the period of time in which a part of the embedded continuous root-end sequence or the covered continuous root-end sequence is retained in the heated die, thereby stepwise consolidating the roving or reinforcement material and binding into a pre-form. The heated die may also constantly apply heat to the embedded continuous root-end sequence or the covered continuous root-end sequence.

[0094] An objective of the invention is achieved by a continuous strand for manufacturing a root-end component for a wind turbine blade. The continuous strand comprising successively along a process direction: a continuous root-end sequence, the continuous root-end sequence comprises repeats of two successive bushings followed by a core arranged along the process direction; a wrapped continuous root-end sequence, where a first layer comprising one or more layers of reinforcement material is wrapped around the continuous root-end sequence; and either an embedded continuous root-end sequence, where the wrapped continuous root-end sequence is embedded in a second layer comprising roving with a binding agent; and a pre-formed continuous root-end sequence, where the roving and binding agent of the embedded continuous root-end sequence is consolidated, or an embedded continuous root-end sequence, where the wrapped continuous root-end sequence is embedded in a second layer comprising roving; a covered continuous root-end sequence, where the embedded continuous rootend sequence is wrapped in a third layer comprising one or more layers of reinforcement material with a binding agent; and a pre-formed continuous root-end sequence, where the roving and binding agent of the covered continuous root-end sequence is consolidated.

[0095] Any technical effects, advantages, and embodiments described above for the method of manufacturing a pre-formed root-end component for a wind turbine blade are equally relevant and applicable for the continuous strand for manufacturing a root-end component for a wind turbine blade.

[0096] The continuous strand may be produced with a method according to any one of claims 1 to 26.

[0097] An objective of the invention is achieved by a continuous root-end sequence for manufacturing a root-end component for a wind turbine blade. The continuous root-end sequence comprises repeats of two successive bushings followed by a core arranged along a process direction. Any technical effects, advantages, and embodiments described above for the method of manufacturing a pre-formed root-end component for a wind turbine blade are equally relevant and applicable for the continuous root-end sequence for manufacturing a rootend component for a wind turbine blade.

[0098] The continuous root-end sequence may be produced with a method according to any one of claims 1 to 26.

[0099] An objective of the invention is achieved by a wrapped continuous root-end sequence for manufacturing a root-end component for a wind turbine blade. The wrapped continuous root-end sequence comprises: a continuous root-end sequence comprising repeats of two successive bushings followed by a core arranged along a process direction, and a first layer comprising one or more layers of reinforcement material wrapped around the continuous root-end sequence.

[0100] Any technical effects, advantages, and embodiments described above for the method of manufacturing a pre-formed root-end component for a wind turbine blade are equally relevant and applicable for the wrapped continuous root-end sequence for manufacturing a root-end component for a wind turbine blade.

[0101] The wrapped continuous root-end sequence may be produced with a method according to any one of claims 1 to 26.

[0102] An objective of the invention is achieved by an embedded continuous root-end sequence for manufacturing a root-end component for a wind turbine blade. The embedded continuous root-end sequence comprises a continuous root-end sequence comprising repeats of two successive bushings followed by a core arranged along a process direction, a first layer comprising one or more layers of reinforcement material wrapped around the continuous root-end sequence, and a second layer comprising roving with or without binding agent embedding the first layer of reinforcement material. Any technical effects, advantages, and embodiments described above for the method of manufacturing a pre-formed root-end component for a wind turbine blade are equally relevant and applicable for the embedded continuous root-end sequence for manufacturing a root-end component for a wind turbine blade.

[0103] The embedded continuous root-end sequence may be produced with a method according to any one of claims 1 to 26.

[0104] An objective of the invention is achieved by an covered continuous root-end sequence for manufacturing a root-end component for a wind turbine blade, the embedded continuous root-end sequence comprises: a continuous root-end sequence comprising repeats of two successive bushings followed by a core arranged along a process direction, a first layer comprising one or more layers of reinforcement material wrapped around the continuous root-end sequence, a second layer comprising roving embedding the first layer of reinforcement material, and a third layer comprising one or more layers of reinforcement material with a binding agent wrapped around the second layer of roving.

[0105] Any technical effects, advantages, and embodiments described above for the method of manufacturing a pre-formed root-end component for a wind turbine blade are equally relevant and applicable for the covered continuous root-end sequence for manufacturing a root-end component for a wind turbine blade.

[0106] The covered continuous root-end sequence may be produced with a method according to any one of claims 1 to 26.

[0107] An objective of the invention is achieved by a pre-formed continuous root-end sequence for manufacturing a root-end component for a wind turbine blade. The pre-formed continuous root-end sequence comprises a continuous root-end sequence comprising repeats of two successive bushings followed by a core arranged along a process direction, a first layer comprising one or more layers of reinforcement material wrapped around the continuous root-end sequence, and either a second layer comprising roving with binding agent embedding the first layer, wherein the roving and binding agent are consolidated or a second layer comprising roving embedding the first layer of reinforcement material, and a third layer comprising one or more layers of reinforcement material with a binding agent wrapped around the second layer of roving, wherein the third layer is consolidated.

[0108] Any technical effects, advantages, and embodiments described above for the method of manufacturing a pre-formed root-end component for a wind turbine blade are equally relevant and applicable for the pre-formed continuous root-end sequence for manufacturing a root-end component for a wind turbine blade.

[0109] The pre-formed continuous root-end sequence may be produced with a method according to any one of claims 1 to 26.

[0110] An objective of the invention is achieved by a pre-formed root-end component for a wind turbine blade, wherein the root-end component comprises a bushing having a first end, and a second end; a core arranged adjacent to the second end of the bushing; a first layer comprising one or more layers of reinforcement material covering an exterior surface of the bushing and the core; and either a second layer comprising roving with a binding agent surrounding the first layer; wherein the second layer is consolidated into a pre-form or a second layer comprising roving surrounding the first layer; and a third layer comprising one or more layers of reinforcement material with a binding agent wrapped around the second layer, wherein the third layer is consolidated inro a pre-from. Any technical effects, advantages, and embodiments described above for the method of manufacturing a pre-formed root-end component for a wind turbine blade are equally relevant and applicable for the pre-formed root-end component for a wind turbine blade.

[0111] The pre-formed root-end component of the present invention significantly reduces the number of bonding interfaces in the root region of a wind turbine blade, due to the bushing being embedded in the fibre-reinforced material of the root-end component, thereby significantly increasing the fatigue-resistance of the root region capable of withstanding the loads from the wind turbine blade on the blade -hub connection.

[0112] The pre-formed root-end component, furthermore, provides a stronger bonding of the bushing to the fibre-reinforcement material surrounding the bushing and, thus, a fatigueresistant interface between the bushing and the fibre -reinforcement material. The preformed root-end component, therefore, has considerable structural improvements increasing the pull-resistance of and providing considerable stronger connections to bushings in the root region of the wind turbine blade.

[0113] The bushings may be elongate bushing extending along an axis. The first end of the bushing may be configured for receiving a bolt or threaded rod on a hub. The first end of the bushing may constitute a first end of the pre-formed root-end component configured for receiving a threaded rod or bolt in a blade-hub connection. The bushing may further comprise a body region extending between the first end and the second end. The bushings may further comprise an internal threaded bore extending from an opening in the first receiving end towards the second end inside the body region. The exterior surface of the body region may optionally comprise circumferential grooves, thereby providing greater friction, stronger binding interface and, thus, a greater pull resistance between the bushings and the first layer of reinforcement material. Optionally, the bushing may have a substantially cylindrical exterior surface. The bushing may have a substantially conical shape. However, it should be noted that the pre-formed root-end component of the present invention is not dependent on the bushing design, thus, any bushing with any bushing design suitable for engaging in a blade-hub connection may be utilised for the present invention.

[0114] The bushing is metal bushing, preferably a steel bushing. 1

[0115] The core may be an elongate core extending along an axis parallel and may be fibrous. In an embodiment, the core is made of a glass fibre reinforced polymer or a thermoplastic foam or unidirectional (UD) fabric or UD roving or texturized glass roving or texturized glass fabric or a preform of any of these. The preforms are advantageous, as a resin matrix may infuse into the core during a resin infusion of the pre-formed rootend component, thereby, providing a stronger bonding between the interfaces in the preformed root-end component. In an embodiment, the core and the bushing may have the same diameter, and optionally, the core may have a substantially cylindrical exterior surface.

[0116] The reinforcement material may be fabrics or roving or mats, and wherein the fabrics, roving, or mats are made of glass, fibreglass, carbon, carbon fibres, UD glass, or texturized glass. The reinforcement material may further be bundles of filaments or tows of filamentary material of any of the above-mentioned materials. The reinforcement material may furthermore be aramid, basalt, paper, wood, boron, asbestos, or any combination thereof.

[0117] In an embodiment, the pre-formed root-end component further comprises an adhesive layer comprising adhesive or glue between the bushing and the first layer. The adhesive layer, thereby, at least partly adheres the first layer to the bushing, while still allowing the first layer to be infused with resin with the rest of the pre-formed root-end component during a subsequent resin infusion. The adhesive may also be applied to an exterior surface of the core. The adhesive layer thus strongly anchors the first layer to the exterior surface of the bushing in the pre-formed root-end component, providing a fatigueresistant interface between the first layer and bushing. The adhesive layer, therefore, prevents that the bushing being insufficiently retained in the fibre-reinforced material of the pre-formed root end component and, thus, in root region of the wind turbine blade, thereby, preventing or at least significantly reducing the risk of the bushing being pulled out of the fibre-reinforced material in the root region by the loads from the wind turbine blade on the blade -hub connection.

[0118] In another embodiment, the first layer of reinforcement material may be a applied an adhesive or glue, the adhesive layer on the reinforcement material then strongly anchors the first layer to the exterior surface of the bushing in the pre-formed root-end component, providing a fatigue-resistant interface between the first layer and bushings.

[0119] The second layer of roving with or without a binding agent may be UD glass roving and / or texturized glass roving. The binding agent may be a thermosetting polymer, a thermoplastic polymer, an adhesive, epoxy resin, vinyl ester, a polyester thermosetting plastic, phenol formaldehyde resin, a thermoplastic powder binder, a thermoplastic resin, a thermoplastic resin system, or any combination thereof. Preferably the polymer is a thermoplastic powder binder and / or an adhesive and / or an epoxy resin. The thermoplastic resin system may be a thermoplastic resin sold under the trademark name Elium® or any other recyclable thermoplastic resin system.

[0120] In an embodiment, the pre-formed root-end component has a cross-sectional geometry comprising the continuous root-end sequence having a substantially circular cross-sectional geometry surrounded by the first layer having a substantially circular cross-sectional geometry, the first layer being surrounded by the second layer having a cross- sectional geometry being a substantially square shaped or substantially rectangular shaped cross-sectional geometry, or comprising a first par and a second part being displaced relative to each other, or comprising a first part, a second part, and a third part arranged between the first and second part, where the third part is displaced relative to the first and second part.

[0121] The first, second and third parts of the second layer cross-sectional geometry may have a substantially rectangular shaped cross-sectional-geometry.

[0122] A substantially square shaped cross-sectional geometry of the second layer increases the interface between two pre-formed root-end components arranged adjacent to each other in the root region of a wind turbine blade, thereby increasing the boding strength between two adjacent pre-formed root-end components in the interface.

[0123] A second layer having a cross-sectional geometry comprising two or three parts displaced relative to each other further increases the interface between two pre-formed root-end components arranged adjacent to each other in the root region of a wind turbine blade, thereby further increasing the bonding strength between two adjacent pre-formed root-end components in the interface. The displaced parts, furthermore, provides a lateral face of the pre-formed root end component which can interlock with a lateral face of an adjacent pre-formed root-end component, thereby interlocking adjacent preformed root-end components to each other in the root region for a stronger mounting of the pre-formed root-end components in the wind turbine blade, providing a greater pullresistance and a stronger blade-hub connection.

[0124] The third layer may have the same cross-sectional geometry as the second layer or the second layer may have a substantially circular cross-sectional geometry, where the third layer has a cross-sectional geometry of the second layer according to one of the abovedescribed configurations.

[0125] The pre-formed root-end component may have a cross-section size of 6-18 cm in height and 6-18 cm in width. The cross-section size may be dependent on the size and dimensions of the wind turbine blade.

[0126] The pre-formed root-end component may comprise a first end comprising the bushing being substantially straight and perpendicular to an axis extending along the body of the bushing. The first end of the pre-formed root-end component being suitable for engaging in a blade-hub connection. The pre-formed root-end component may further comprise second end comprising the core, wherein the pre-formed root-end component may comprise has a wedged- shaped towards the second end, thereby providing a chamfered pre-formed root-end component. The amount of material in pre-formed root-end component is, thus, reduced, providing a lighter pre-formed root-end component, which is advantageous for use in a wind turbine blade, because a reduced weight of the wind turbine blade reduces the load from the wind turbine blade on the blade-hub connection. The wedged-shape further increases the binding strength of the pre-formed root-end component to a root region of a wind turbine blade.

[0127] The pre-formed root-end component may be produced with a method according to any one of claims 1 to 26. An objective of the invention is achieved by a wind turbine blade comprising a blade shell structure comprising a root region for attachment to a rotor hub, wherein a plurality of pre-formed root-end components according to claim 33 being arranged for securing the wind turbine blade to the rotor hub are arranged in the root region such that the plurality of pre-formed root-end components follow a circumference of the root region cross section, and wherein a lateral face of the pre-formed root end components engages a lateral face of an adjacent pre-formed root-end component.

[0128] Thereby providing a wind turbine blade with a root region for connecting to a hub with a significantly reduced the number of bonding interfaces, due to the bushing being embedded in the fibre-reinforced material of the root-end component, and a stronger bonding of the bushing to the fibre-reinforcement material surrounding the bushing creating a fatigue-resistant interface between the bushing and the fibre-reinforcement material. Thereby, significantly increasing pull-resistance of the bushings and increasing the fatigue-resistance of the root region capable of withstanding the loads from the wind turbine blade on the blade-hub connection and providing considerable stronger connections to bushings in the root region of the wind turbine blade.

[0129] Thus, the wind turbine blade of the present invention circumvents the need for separate reinforcement inserts arranged between adjacent bushings and embedded in the root region of the wind turbine blade, which is associated with a weak binding interface between bushings, the reinforcement inserts and the blade shell.

[0130] Any technical effects, advantages, and embodiments described above for the method of manufacturing a pre-formed root-end component for a wind turbine blade and for the pre-formed root-end component for a wind turbine blade are equally relevant and applicable for the wind turbine blade of the present invention.

[0131] In an embodiment, an intermediate layer with 20-65% out of plane glass fibre fabric or glass fibre mat is arranged between adjacent pre-formed root-end components and engaging a lateral face of adjacent pre-formed root-end components before a resin infusion of the root region and / or the entire wind turbine blade shell mould. The intermediate layer does not need to be applied a binding agent prior to arrangement in the root region, because the intermediate layer will be reinforced with the resin from the resin infusion. By sticking out of plane is meant that the fibres or part of fibres extend in a direction which is non-parallel with the two largest surfaces of the fabrics or mats.

[0132] When assembling the pre-formed root-end components in the root region mould for resin infusion, the intermediate layer may cover one or two lateral surfaces of adjacent pre-formed root-end components or the intermediate layer may cover all surfaces of the assembly of pre-formed root-end components. The intermediate layer creates small spacings between adjacent pre-formed root-end components which may subsequently be infused with resin, thereby providing a stronger bonding of the pre-formed root-end components in the root region.

[0133] The area weight of the intermediate layer may be 100-800 gsm, or preferably 150 - 400 gsm.

[0134] The intermediate layer could be applied to the to the lateral surfaces of the pre-formed continuous root-end sequence the prior to the step passing the pre-formed continuous root-end sequence through a heated die in the method for manufacturing a pre-formed root-end component for a wind turbine blade. Thereby, the intermediate layer will be pre-formed onto the lateral surfaces of the pre-formed root-end components.

[0135] An objective of the invention is achieved by a method for manufacturing a wind turbine blade. The method comprises steps of providing a blade shell structure comprising a root region for attachment to a rotor hub; manufacturing a plurality of pre-formed root-end components according to a method of any of claims 1-26 or providing a plurality of pre-formed root-end components according to claim 33, wherein the pre-formed root-end components are arranged for securing the wind turbine blade to the rotor hub; arranging the plurality of pre-formed root-end components in the root region such that the plurality of pre-formed root-end components follow a circumference of the root region cross section, and a lateral face of the pre-formed root end components engages a lateral face of an adjacent pre-formed root-end component, thereby providing a root region assembly; infusing a resin into the root region assembly, and curing the resin for fixing the plurality of pre-formed root-end components within the root region of the blade shell structure.

[0136] Thereby, the method provides a wind turbine blade having a root region for connecting to a hub circumventing or at least significantly reducing the number of interfaces in the root region and, thus, preventing weak interfaces in the root region and increasing the fatigue strength of the root region, which is capable of withstanding the loads on the blade -hub connection. This method is further advantageous, as the resin infusion of the assembly of pre-formed root-end components arranged in the root region can be run along with the resin infusion of the wind turbine blade mould.

[0137] In an embodiment, the method, prior to the step of infusing, comprises a step of arranging an intermediate layer with 20-65% out of plane glass fibre fabric or glass fibre mats between adjacent pre-formed root-end components such that the intermediate layer engages the lateral faces of adjacent pre-formed root-end components.

[0138] Any technical effects, advantages, and embodiments described above for the method of manufacturing a pre-formed root-end component for a wind turbine blade and for the wind turbine blade are equally relevant and applicable for the method for manufacturing a wind turbine blade.

[0139] An objective of the invention is achieved by an apparatus for manufacturing a preformed root-end component for a wind turbine blade. The apparatus comprising: a loading module for loading repeats of two successive bushing followed by a core along a process direction, thereby providing a continuous root-end sequence; a wrapping module for wrapping the continuous root-end sequence in a first layer comprising one or more layers of reinforcement material, thereby providing a wrapped continuous root-end sequence; and either an embedding module for embedding the wrapped continuous root-end sequence in a second layer comprising roving with a binding agent along the process direction, thereby providing an embedded continuous root-end sequence; or an embedding module for embedding the wrapped continuous root-end sequence in a second layer comprising roving along the process direction (X), thereby providing an embedded continuous root-end sequence; and a second wrapping module for wrapping the embedded continuous root-end sequence in a third layer comprising one or more layers of reinforcement material with a binding agent along the process direction, thereby providing a covered continuous root-end sequence; and a heated die for consolidating the rovings and binding agent of the second layer or the third layer into a pre-formed continuous root-end sequence along the process direction; and a pulling system for continuously or stepwise passing a continuous strand comprising successively along the process direction the continuous root-end sequence, the wrapped continuous root-end sequence, the embedded continuous root-end sequence, and the pre-formed continuous root-end sequence, or the continuous root-end sequence, the wrapped continuous root-end sequence, the embedded continuous root-end sequence, the covered continuous root-end sequence, and the pre-formed continuous root-end sequence, through the apparatus along the process direction.

[0140] Any technical effects, advantages, and embodiments described above for the method of manufacturing a pre-formed root-end component for a wind turbine blade and for the pre-formed root-end component for a wind turbine blade are equally relevant and applicable for the apparatus for manufacturing a preformed root-end component for a wind turbine blade.

[0141] Thereby providing an apparatus for continuously producing pre-formed root-end components for a wind turbine blade. The apparatus enables that pre-formed root-end components for a wind turbine blade can be manufactured in plurality and automatically, thereby providing effective and cost-efficient continuous production of pre-formed root-end components. The apparatus further provides pre-formed root-end components for utilisation in a root region of wind turbine blade for connecting the wind turbine blade with a hub, which significantly reduces the number of bonding interfaces in the root region, thereby significantly increasing the fatigue-resistance of the root region capable of withstanding the loads from the wind turbine blade on the blade-hub connection. Furthermore, the apparatus manufactures pre-formed root-end components with an embedded bushing, thereby providing a stronger bonding of the bushing to the fibre-reinforced material surrounding the bushing and, thus, providing a fatigue-resistant interface between the bushing and the fibre-reinforced material. The apparatus, therefore, provide considerable structural improvements of the pre-formed root-end components, increasing the pull-resistance of and providing considerable stronger connections to bushings in the root region of the wind turbine blade.

[0142] The first and / or second wrapping modules may be configured for filament winding reinforcement material around the continuous root-end sequence and / or the covered continuous root-end sequence or for folding fabrics or mats around the continuous root-end sequence and / or the covered continuous root-end sequence.

[0143] The first and / or second wrapping modules and / or embedding module may be configured for wrapping the continuous root-end sequence and / or embedding the wrapped continuous root-end sequence and / or the covered continuous root-end sequence along the process direction.

[0144] The embedding module may be configured for embedding the wrapped continuous rootend sequence in a second layer of roving having a thickness filling out the space in the heated die or optionally a preforming die, wherein the second layer is shaped or moulded to a cross-sectional geometry corresponding to the cross-sectional geometry of the heated die or optionally the preforming die, thereby providing the embedded continuous root-end sequence and, thus, the resulting pre-formed root-end component with a desired cross-sectional geometry suitable for being arranged in a root region of a wind turbine blade.

[0145] The heated die may encompass a part of the embedded continuous root-end sequence or the covered continuous root-end sequence at a time. Thereby, the heated die applies heat to a part of the embedded continuous root-end sequence or the covered continuous root-end sequence at the time to consolidate the roving or reinforcement material and binding agent into a pre-form. The heated die heats the embedded continuous root-end sequence or the covered continuous root-end sequence to consolidate the roving or reinforcement material and binding agent into a pre-form, thereby at least partially melting and / or polymerizing the binding agent to unite the roving or reinforcement material and binding agent into a pre-form. The consolidation of the roving or reinforcement material and binding, thus, provides a pre-formed continuous root-end sequence with a stiffness and curing degree that is high enough for the pre-formed continuous root-end sequence to maintain its shape and preferably for a subsequent infusion of resin, the pre-formed continuous root-end sequence without the need of a mould.

[0146] The pulling system may pass the continuous strand continuously through the apparatus without stopping or pass the continuous strand stepwise through the heated die, where the continuous strand is retained in each module for a period of time. The pulling system may be configured for passing the continuous strand through the apparatus a speed of 4-25 meter per hour or preferably 6-12 meter per hour.

[0147] In an embodiment, the apparatus may further comprise one or more creel systems for holding roles of the reinforcement material for the first and / or second wrapping modules and / or holding roles of roving for the embedding module. The creel system provides an organized method for delivering the reinforcement material to the wrapping modules and / or the roving to the embedding module, and further provides tension regulations of the reinforcement material and / or roving such that the reinforcement material and / or roving is provided to their respective modules with even tension. The creel system may comprise a guiding system for guiding the reinforcement material and / or roving.

[0148] In an embodiment, the apparatus comprises a preforming die arranged before the heated die, the preforming die having a pre-determined cross-sectional geometry for pre-shaping the embedded continuous root-end sequence or the covered continuous root-end sequence to a pre-determined cross-sectional geometry, thereby pre-shaping the embedded continuous root-end sequence or the covered continuous root-end sequence into the correct shape for easier loading into the heated die. In an embodiment, the apparatus comprises an adhesive application module for applying adhesive or glue to an exterior surface of the bushings or to the reinforcement material before wrapping. The adhesive application module may also apply adhesive or glue to an exterior surface of the core.

[0149] In an embodiment, the apparatus comprises a cutting system for cutting the pre-formed continuous root-end sequence along a first cutting line arranged between the two successive bushings and along a second cutting line arranged through the core, thereby providing a pre-formed root-end component. The cutting system may be configured for cutting the pre-formed continuous root-end sequence along a first cutting line perpendicular to the process direction and along the second cutting line being angled relative to the process direction, where the angle of the second cutting line relative to the process direction is 2-12 degrees or preferable 3-6 degrees. Thereby providing a chamfered preformed root-end component.

[0150] In an embodiment, the loading module may provide a spacer arranged between the two successive bushings, wherein the first cutting line may be arranged through a spacer.

[0151] In an embodiment, the apparatus comprises a binding agent feed module arranged prior to the embedding module or the second wrapping module, the binding agent feed module being configured for applying binding agent to the roving prior to embedding or the reinforcement material of the third layer prior to wrapping.

[0152] The binding agent feeding module may be configured for spraying binding agent onto the roving or the reinforcement material to obtain an even distribution of binding agent on the roving surface of a surface of the reinforcement material, respectively, thereby reducing the amount of binding agent needed for consolidating the roving or reinforcement material and binding agent.

[0153] The binding agent feed module may be configured for applying 1-10% or 1- 7% or preferably 1-5% binding agent, thereby applying a sufficient amount of binding agent to the roving or reinforcement material for consolidating the roving or reinforcement material and binding agent to a stiffness and curing degree that enables subsequent resin infusion of the pre-formed continuous root-end sequence or pre-formed root-end components. 31

[0154] Description of the Drawing

[0155] Various examples are described hereinafter with reference to the figures. Like reference numerals refer to like elements throughout. Like elements will thus not be described in detail with respect to the description of each figure. It should also be noted that the figures are only intended to facilitate the description of the examples. They are not intended as an exhaustive description of the claimed invention or as a limitation on the scope of the claimed invention. In addition, an illustrated example need not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular example is not necessarily limited to that example and can be practiced in any other examples even if not so illustrated, or if not so explicitly described.

[0156] Embodiments of the invention will be described in the figures, whereon:

[0157] Fig. 1 illustrates a pre-formed root-end component and a pre-formed continuous rootend sequence according to an embodiment of the invention.

[0158] Fig. 2 illustrates different cross-sectional geometries of a pre-formed root-end component and a pre-formed continuous root-end sequence according to an embodiment of the invention.

[0159] Fig. 3 illustrates an apparatus for manufacturing a pre-formed root-end component according to an embodiment of the present invention.

[0160] Fig. 4 illustrates a pre-formed root-end component and a pre-formed continuous rootend sequence according to an embodiment of the invention.

[0161] Fig. 5 illustrates cross-sectional view of a section of a blade shell structure with a plurality of pre-formed root-end components according to an embodiment of the invention.

[0162] Fig. 6 illustrates an apparatus for manufacturing a pre-formed root-end component according to an embodiment of the present invention.

[0163] Detailed Description of the Invention

[0164] Exemplary examples will now be described more fully hereinafter with reference to the accompanying drawings. In this regard, the present examples may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the examples are merely described below, by referring to the figures, to explain aspects. The terminology used herein is for the purpose of describing particular examples only and is not intended to be limiting. As used herein, the terms “comprises”, “comprising”, “includes”, and / or “including”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0165] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this invention pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined in the present specification.

[0166] Figure 1A illustrates a pre-formed root-end component 10 for a wind turbine blade according to an embodiment of the present invention. The pre-formed root-end component 10 comprises a bushing 110 having a first end, and a second end, a core 120 arranged adjacent to the second end of the bushing 110, a first layer 210 (not shown) comprising one or more layers of reinforcement material covering an exterior surface of the bushing 110 and the core 120, and second layer 310 comprising roving with a binding agent surrounding the first layer 210, wherein the second layer 310 is consolidated into a preform.

[0167] The bushings 110 may be an elongate bushing 110 extending along an axis. The first end of the bushing 110 may be configured for receiving a bolt or threaded rod on a hub. The first end of the bushing 110 may be contained in a first end 12 of the pre-formed root-end component 10 configured for receiving a threaded rod or bolt in a blade-hub connection. The bushing 110 may further comprise a body region extending between the first end and the second end of the bushing 110. The bushing 110 may further comprise an internal threaded bore extending from an opening in the first end of the bushing 110 towards the second end inside the body region, wherein the threaded bore is configured for receiving a bolt or a threaded rod. The exterior surface of the body region may optionally comprise circumferential grooves, thereby providing greater friction, stronger binding interface and, thus, a greater pull resistance between the bushings 110 and the first layer 210 of reinforcement material. Optionally, the bushing may have a substantially cylindrical exterior surface. The bushing 110 may further be a metal bushing, preferably a steel bushing.

[0168] The core 120 may be an elongated core 120 extending along an axis parallel and may be fibrous. In an embodiment, the core 120 is made of a glass fibre reinforced polymer or a thermoplastic foam or unidirectional (UD) fabric or UD roving or texturized glass roving or texturized glass fabric or a preform of any of these. The preforms are advantageous, as a resin matrix may infuse into the core 120 during a resin infusion of the pre-formed root-end component 10, thereby reducing the interfaces in the pre-formed root-end component 10. In an embodiment, the core 120 and the bushing 110 may have the same diameter, and optionally, the core 120 may have a substantially cylindrical exterior surface.

[0169] The reinforcement material of first layer 210 may forms corrugations on the surface of the first layer 210. These corrugations increase the friction between the first layer 210 and second layer 310, thereby providing a fatigue-resistant interface between the first layer 210 and second layer 310 with an increased fatigue strength capable of withstanding the loads from the wind turbine blade on the blade -hub connection.

[0170] The reinforcement material of the second layer 210 may be fabrics or roving or mats, and wherein the fabrics, roving, or mats are made of glass, fibreglass, carbon, carbon fibres, UD glass, or texturized glass. The reinforcement material may further be bundles of filaments or tows of filamentary material of any of the above-mentioned materials. The reinforcement material may furthermore be aramid, basalt, paper, wood, boron, asbestos, or any combination thereof.

[0171] In an embodiment, the pre-formed root-end component 10 further comprises an adhesive layer (not shown) comprising adhesive or glue between the bushing 110 and the first layer 210. The adhesive layer at least partly adheres the first layer 210 to the bushing 110, while still allowing the first layer 210 to be infused with resin with the rest of the pre-formed root-end component 10 during a subsequent resin infusion. The adhesive layer, thereby, strongly anchors the first layer 210 to the exterior surface of the bushing 110, providing a fatigue-resistant interface between the first layer 210 and bushing 110. The adhesive layer may have an adhesive layer thickness of 0.5-10 mm or preferably 2- 5 mm. The adhesive layer may also have an adhesive layer thickness of 0.1-5 mm or 0.1-0.5 mm or preferably 0.2-0.5 mm or more preferably about 0.3 mm.

[0172] In another embodiment, the adhesive layer comprising adhesive or glue may be applied on the reinforcement material of the first layer 210.

[0173] The second layer 310 surrounding the first layer 210 may provide the pre-formed rootend component 10 with a desired cross-sectional geometry suitable for being arranged in a root region of a wind turbine blade. Figure 1C illustrates a front view of a preformed root-end component 10 having a substantially square cross-sectional geometry.

[0174] Figure 4 illustrates another embodiment of a pre-formed root-end component 10 and a pre-formed continuous root-end sequence 400, wherein the second layer 310 comprises roving without a binding agent surrounding the first layer 210, and where the second layer 310 is surrounded by a third layer 610 comprising one or more layers of reinforcement material with a binding agent. In this embodiment, the second layer 310 or the third layer 610 may provide the pre-formed root-end component 10 with a desired cross- sectional geometry suitable for being arranged in a root region of a wind turbine blade. Figure 4B illustrates a front view of a pre-formed root-end component 10 having a substantially square cross-sectional geometry.

[0175] The second layer 210 of roving with or without binding agent of the second layer 310 surrounding the first layer 210 may be UD glass roving and / or texturized glass roving, and the binding agent may be a thermosetting polymer, a thermoplastic polymer, an adhesive, epoxy resin, vinyl ester, a polyester thermosetting plastic, phenol formaldehyde resin, a thermoplastic powder binder, a thermoplastic resin, a thermoplastic resin system, or any combination thereof. Preferably the polymer is a thermoplastic powder binder and / or an adhesive and / or an epoxy resin. The thermoplastic resin system may be a thermoplastic resin sold under the trademark name Elium® or any other recyclable thermoplastic resin system. The roving and binding agent of the second layer 310 or the reinforcement material and binding agent of the third layer 610 may be consolidated to a stiffness and curing degree that is high enough for pre-formed root-end component 10 to maintain its shape and low enough for infusing resin into the pre-formed root-end component 10.

[0176] The pre-formed root-end component 10 may comprise a first end 12 comprising the bushing 110 being substantially straight and perpendicular to an axis extending along the body of the bushing 110. The first end 12 of the pre-formed root-end component 10 being suitable for engaging in a blade -hub connection. The pre-formed root-end component 10 may further comprise second end 14 comprising the core 120, wherein the pre-formed root-end component 10 may have a wedged-shaped towards the second end 14, thereby providing a chamfered pre-formed root-end component 10.

[0177] In an embodiment, the bushing 110 may comprises one, two, three, or more holes. In a preferred embodiment, the bushing 110 comprises one hole. The holes may be located in the body of the bushing 110 and / or in the second end of the bushing 110 and be in fluid connection with the bore of the bushing 110. The holes can be utilised for infusing resin into the pre-formed root-end component 10, thereby achieving a better distribution of resin within the fibre material of the core 120, first layer 210 and second layer 310 or of the core 120, first layer 210, second layer 310, and the third layer 610 of the preformed root-end component 10, thereby firmly anchoring the bushing 110 within the pre-formed root-end component.

[0178] Figure IB illustrates a pre-formed continuous root-end sequence 400 for manufacturing a pre-formed root-end component 10 according to an embodiment of the invention. The pre-formed continuous root-end sequence 400 comprises a continuous root-end sequence, wherein the continuous root-end sequence comprises repeats of two successive bushings 110 followed by a core 120 arranged along a process direction X.

[0179] The continuous root-end sequence, the two successive bushing 110 may be arranged with their respective first ends facing each other, thereby having their second ends facing an end of a core 130. In an embodiment, a spacer 130 may be arranged between the two successive bushings 110. The spacer enables localization and identification of a first cutting line 20 between the two successive bushings 110, thereby preventing cutting into the bushings 110, when the pre-formed continuous root-end sequence 400 is cut into pre-formed root-end components 10. The space 130 may further function as a seal of the first end comprising opening of the bushings 110, thereby preventing any resin, binding agent, adhesive, or glue from leaking inside the bore of the bushing 110. The second end of the bushing 110 may be automatically sealed in the pre-formed continuous root-end sequence 400 by the core 130.

[0180] The pre-formed continuous root-end sequence 400 further comprises a first layer 210 comprising one or more layers of reinforcement material surrounding the continuous root-end sequence , thereby anchoring the first layer 210 to surface of the continuous root-end sequence. In embodiments, where the exterior surface of the bushings 110 comprises grooves, the first layer 210 may be anchored into the grooves.

[0181] In an embodiment, the pre-formed continuous root-end sequence 400 further comprises an adhesive layer (not shown) comprising adhesive or glue between the bushing 110 and the first layer 210. The adhesive layer may have an adhesive layer thickness of 0.5- 10 mm or preferably 2-5 mm. The adhesive layer may have an adhesive layer thickness of 0.1-5 mm or 0.1-0.5 mm or preferably 0.2-0.4 mm or more preferably about 0.3 mm.

[0182] In another embodiment, the adhesive layer comprising adhesive or glue may be applied on the reinforcement material of the first layer 210.

[0183] The pre-formed continuous root-end sequence 400 further comprises a second layer 310 comprising roving with a binding agent surrounding the first layer 210, wherein the roving and binding agent is consolidated to pre-form. The second layer 310 surrounding the first layer 210 may provide the pre-formed continuous root-end sequence 400 with a desired cross-sectional geometry. Figure 1C illustrates a front view of a pre-formed continuous root-end sequence 400 having a substantially square cross-sectional geometry. Figure 4A illustrates another embodiment of a pre-formed continuous root-end sequence 400, wherein the second layer 310 comprises roving without a binding agent surrounding the first layer 210, and where the second layer 310 is surrounded by a third layer 610 comprising one or more layers of reinforcement material with a binding agent, wherein the reinforcement material and binding agent is consolidated to pre-form.

[0184] In an embodiment, the pre-formed continuous root-end sequence 400 may further comprise an intermediate layer 700 with 20-65% out of plane glass fibre fabric or glass fibre mat and applied with a binding agent, which is arranged one lateral surface 16 or two opposing lateral surfaces 16 of the pre-formed continuous root-end sequence 400, wherein the intermediate layer and binding agent is consolidated. When arranging preformed root-end components 10 having an intermediate layer arranged on one lateral surface 16 or two opposing lateral surfaces 16 in the root region mould for resin infusion, the intermediate layer is arranged between the lateral surfaces 16 of adjacent preformed root-end components 10, thereby the intermediate layer creates small preformed spacings between adjacent pre-formed root-end components 10, which may subsequently be infused with resin. This provides a stronger bonding of the pre-formed root-end components lOin the root region. Figure 5 illustrates a cross-sectional view of a plurality of pre-formed root-end components 10 having an intermediate layer 700 arranged on adjacent lateral surfaces 16 of the pre-formed root-end components 10, wherein the plurality of pre-formed root-end components 10 are arranged in a section of a blade shell structure 2000.

[0185] Figure 2 illustrates different cross-sectional geometries of a pre-formed root-end component 10 or a pre-formed continuous root-end sequence 400 according to an embodiment of the invention.

[0186] The pre-formed root-end component 10 or pre-formed continuous root-end sequence 400 may have a cross-sectional geometry comprising the bushing 110 and / or core 130 having a substantially circular cross-section surrounded by the first layer 210 having a substantially circular cross-section, and the first layer 210 surrounded by the second layer 310 having a substantially square shaped cross-section. This is illustrated in figure 2B and figure 1C. A substantially square shaped cross-section of the second layer 310 increases the interface between two pre-formed root-end components 10 arranged adjacent to each other in the root region of a wind turbine blade, thereby increasing the bonding strength between two adjacent pre-formed root-end components 10 in the interface.

[0187] In another embodiment, the pre-formed root-end component 10 or pre-formed continuous root-end sequence 400 may have a cross-sectional geometry comprising the bushing 110 and / or core 130 having a substantially circular cross-section surrounded by the first layer 210 having a substantially circular cross-section, and the first layer 210 being surrounded by the second layer 310 having a cross-sectional geometry comprising a first part and a second part being displaced relative to each other. This is illustrated in figure 2A. The first and second parts may have a substantially rectangular shaped cross- sectional geometry.

[0188] In another embodiment, the pre-formed root-end component 10 or pre-formed continuous root-end sequence 400 may have a cross-sectional geometry comprising the bushing 110 and / or core 130 having a substantially circular cross-section surrounded by the first layer 210 having a substantially circular cross-section, and the first layer 210 being surrounded by the second layer 310 having a cross-sectional geometry comprising a first part, a second part, and a third part arranged between the first and second part, where the third part is displaced relative to the first and second part. This is illustrated in figure 2C. The first, second, and third parts may have a substantially rectangular shaped cross- sectional geometry.

[0189] A second layer 310 having a cross-sectional geometry comprising two or three parts displaced relative to each other further increases the interface between two pre-formed root-end components 10 arranged adjacent to each other in the root region of a wind turbine blade, thereby further increasing the bonding strength between two adjacent preformed root-end components 10 in the interface. The displaced parts, furthermore, provides a lateral face 16 of the pre-formed root end component 10 which can interlock with a lateral face 16 of an adjacent pre-formed root-end component 10, thereby interlocking adjacent pre-formed root-end components 10 to each other in the root region for a stronger mounting of the pre-formed root-end components 10 in the wind turbine blade, providing a greater pull-resistance and a stronger blade -hub connection. The pre-formed root-end component 10 or pre-formed continuous root-end sequence 400 may have a cross-section size of 6-18 cm in height and 6-18 cm in width. The crosssection size may be dependent on the size and dimensions of the wind turbine blade.

[0190] In embodiments of the pre-formed root-end component 10 or the pre-formed continuous root-end sequence having a third layer 610, as illustrated in figure 4, the third layer 610 may have the same cross sectional geometry as the second layer 310 or the second layer 310 may have a substantially circular cross sectional geometry, where the third layer 610 has a cross sectional geometry of the second layer 310 according to one of the above described configurations.

[0191] Figure 3 illustrates an apparatus 1000 for manufacturing a pre-formed root-end component 10 for a wind turbine blade according to an embodiment of the present invention. The apparatus 1000 comprising a loading module 1100 for loading repeats of two successive bushing 110 followed by a core 120 along a process direction X, thereby providing a continuous root-end sequence . By providing the continuous root-end sequence, manufacture of a plurality of pre-formed root-end components 10 is enabled, because a simple cutting procedure of the finished pre-formed continuous root-end sequence 400 will provide a plurality of identical pre-formed root-end components 10.

[0192] The apparatus 1000 further comprises a wrapping module 1300 for wrapping the continuous root-end sequence in a first layer 210 comprising one or more layers of reinforcement material, thereby providing a wrapped continuous root-end sequence. By wrapping the first layer 210 around the continuous root-end sequence , the first layer 210 is firmly anchored to the bushing and the core providing a fatigue-resistant interface between bushings 110 and the first layer 210 in the resulting pre-formed root-end component 10.

[0193] Preferably, the reinforcement material of first layer 210, forms corrugations on the surface of the wrapped continuous root-end sequence during wrapping. The corrugations increase the friction between the first layer 210 and a second layer 310 comprising roving with binding agent, thereby providing a fatigue-resistant interface between the first layer 210 and second layer 310 capable of withstanding the loads on the blade-hub connection. The corrugations may naturally occur during the wrapping procedure due to the wrapping process and / or the nature of the reinforcement material, and / or the corrugations may in an embodiment result from the first layer being anchored into grooves on the exterior surface of the bushings.

[0194] The wrapping module may be configured for filament winding the reinforcement material around the continuous root-end sequence or for folding fabrics or mats around the continuous root-end sequence. During filament winding, the reinforcement material may be wound around the continuous root-end sequence along the process direction X. Thereby, the reinforcement material is laid in a geometric pattern to create a structural surface of the wrapped continuous root-end sequence providing a fatigue-resistant interface between the first layer 210 and second layer 310. During folding, the reinforcement material, may form corrugations on the surface of the wrapped continuous rootend sequence due to natural wrinkle formation in the fabrics or mats during folding.

[0195] The first layer 210 may, furthermore, be applied without a binding agent or an adhesive and may be infused with resin in a later resin infusion process, thereby bonding the first layer 210 to the continuous root-end sequence and fixating the first layer 210 in the resulting root-end component 10 or root region of a wind turbine blade.

[0196] In an embodiment, the apparatus 1000 may comprises an adhesive application module 1200 for applying adhesive or glue to an exterior surface of the bushings 110 or to the reinforcement material before wrapping. The adhesive application module 1200, should be configured for applying adhesive or glue with an adhesive layer thickness that covers the entire exterior surface of the bushing 110 and impregnate into the first layer 210 without passing through the first layer 210 and infuse into the second layer 310. Thereby the first layer 210 is partly adhered to the bushing 110, while still allowing the first layer 210 to be infused with resin with the rest of the resulting pre-formed root-end component 10 during a subsequent resin infusion. The adhesive layer, thus, strongly anchors the first layer 210 to the exterior surface of the bushings 110 in the continuous root-end sequence. The adhesive layer thickness may be 0.5-10 mm or preferably 2-5 mm. The adhesive layer thickness may also be 0.1-5 mm or 0.1-0.5 mm or preferably 0.2-0.4 mm or more preferably about 0.3 mm. The adhesive layer prevents that the bushing 110 from being insufficiently retained in the fibre-reinforced material of the pre-formed root end component 10 and, thus, in root region of the wind turbine blade, which prevents or at least significantly reduces the risk of the bushing 110 being pulled out of the fibre- reinforced material in the root region by the loads from the wind turbine blade.

[0197] Following the wrapping module 1300, the apparatus 1000 comprises an embedding module 1400 for embedding the wrapped continuous root-end sequence in a second layer 310 comprising roving with a binding agent, thereby providing an embedded continuous root-end sequence. The embedding module 1400 embeds the wrapped continuous root-end sequence in a second layer 310 of roving having a thickness filling out the space in the heated die 1500 or optionally a preforming die, wherein the second layer 310 is shaped or moulded to a cross-sectional geometry corresponding to the cross- sectional geometry of the heated die 1500 or optionally the preforming die, thereby providing the embedded continuous root-end sequence with a desired cross-sectional geometry suitable for utilisation in a root region of a wind turbine blade.

[0198] The wrapping module 1300 and / or embedding module 1400 may be configured for wrapping the continuous root-end sequence and / or embedding the wrapped continuous root-end sequence along the process direction X.

[0199] Figure 6 illustrates another embodiment of the apparatus 1000, where the embedding module 1400 is configured for embedding the wrapped continuous root-end sequence in a second layer 310 comprising roving without a binding agent, thereby providing an embedded continuous root-end sequence. Following the embedding module 1400, the apparatus 1000 comprises a second wrapping module 1350 for wrapping a third layer 610 comprising one or more layers of reinforcement material with binding agent around the embedded continuous root-end sequence, thereby providing a covered continuous root-end sequence (see figure 4). The second wrapping module 1350 may be configured for filament winding the reinforcement material around the embedded continuous rootend sequence or for folding fabrics or mats around the embedded continuous root-end sequence. During filament winding, the reinforcement material may be wound around the embedded continuous root-end sequence along the process direction X. Thereby, the reinforcement material is laid in a geometric pattern to create a structural surface of the covered continuous root-end sequence providing a fatigue-resistant interface between the second layer 310 and third layer 610. In the first and second wrapping modules 1300, 1350, the reinforcement material of the first layer 210 and / or the third layer 610, may, during folding, form corrugations on the surface of the wrapped continuous root-end sequence and / or covered continuous rootend sequence which increases the surface area if the covered continuous root-end sequence and functions as a mechanical locking of the reinforcement material, wherein the corrugations of first layer 210 interlocks with the second layer 310 and / or the corrugations of third layer 610 interlocks with the surface of the adjacent preformed rootend components 10 in root-end of the blade shell structure 2000 and / or with the material of the blade shell structure 2000.

[0200] The second wrapping module 1350 may be configured for wrapping the embedded continuous root-end sequence along the process direction X.

[0201] In an embodiment, the apparatus 1000 may further comprise a binding agent feed module (not shown) arranged prior to the embedding module 1400 or the second wrapping module 1350, the binding agent feed module is configured for applying binding agent to the roving prior to embedding or to the reinforcement material of the third layer 610 prior to wrapping. The binding agent feeding module may be configured for spraying binding agent onto the roving or the reinforcement material to obtain an even distribution of binding agent on the roving surface or the surface of the reinforcement material, respectively, thereby reducing the amount of binding agent needed for consolidating the roving and binding agent of the second layer 310 or for consolidating the third layer 610.

[0202] The binding agent feed module may apply 1-10% or 1- 7% or preferably 1-5% binding agent, thereby applying a sufficient amount of binding agent to the roving or reinforcement material for consolidating the roving or the reinforcement material and binding agent to a stiffness and curing degree that enables subsequent resin infusion of the preformed root-end components 10.

[0203] In another embodiment, the apparatus 1000 may further comprise one or more creel systems (not shown) for holding roles of the reinforcement material for the wrapping module 1300 and / or the second wrapping station 1350 and / or holding roles of roving for the embedding module 1400. The creel system provides an organized delivery of the reinforcement material to the wrapping module 1300 and / or the second wrapping station 1350 and / or the roving to the embedding module 1400, and further provides tension regulations of the reinforcement material and / or roving such that the reinforcement material and / or roving is provided to their respective modules 1300, 1350, 1400 with even tension. The creel system may comprise a guiding system for guiding the reinforcement material and / or roving.

[0204] The apparatus 1000 further comprises a heated die 1500 for consolidating the roving and binding agent into a pre-formed continuous root-end sequence 400 along the process direction X or for consolidating the third layer 610 into a pre-formed continuous root-end sequence 400 along the process direction X. The heated die 1500 may encompass a part of the embedded continuous root-end sequence or the covered continuous root-end component at a time. Thereby, the heated die 1500 applies heat to a part of the embedded continuous root-end sequence or the covered continuous root-end component at the time to consolidate the roving or reinforcement material and binding agent into a pre-form. The consolidation of the second layer 310 of third layer 610 provides a preformed continuous root-end sequence 400 with a stiffness and curing degree that is high enough for the pre-formed continuous root-end sequence 400 to maintain its shape and preferably for a subsequent infusion of resin into the second layer 310 and the first layer 210 or into the third layer 610, second layer 310, and first layer 210.

[0205] The heated die 1500 may have a cross-sectional geometry providing the pre-formed continuous root-end sequence 400 and, thus, the resulting pre-formed root-end component 10 with a desired cross-sectional geometry suitable for being arranged in a root region of a wind turbine blade. By passing the embedded continuous root-end sequence or the covered continuous root-end component through the heated die the second layer 310 of the embedded continuous root-end sequence or the covered continuous root-end component is compressed and consolidated into the shape of the cross-sectional geometry of the heated die, permanently. The heated die 1500 may be configured for compressing the second layer 310 to a cross-section size of 6-18 cm in height and 6-18 cm in width. The heated die 1500 may further have a die cross-sectional geometry complementary to the cross-sectional geometry of the pre-formed continuous root-end sequence 400. The heated die 1500 may heat the second layer 310 or the third layer 610 to a temperature of 70-180°C or 80-120°C or 90-110°C or preferably about 100°C but is not limited to these temperatures.

[0206] In an embodiment, the apparatus 1000 may comprises a preforming die (not show) arranged before the heated die 1500. The preforming die having a pre-determined cross- sectional geometry for pre-shaping the embedded continuous root-end sequence or the covered continuous root-end component to a pre-determined cross-sectional geometry, thereby pre-shaping the embedded continuous root-end sequence or the covered continuous root-end component into the correct shape for easier loading into the heated die 1500.

[0207] The apparatus 1000 further comprises pulling system (not shown) for continuously or stepwise passing a continuous strand 500 comprising successively along the process direction X the continuous root-end sequence, the wrapped continuous root-end sequence, the embedded continuous root-end sequence, and the pre-formed continuous root-end sequence 400, or the continuous root-end sequence, the wrapped continuous root-end sequence, the embedded continuous root-end sequence, the covered continuous root-end sequence, and the pre-formed continuous root-end sequence 400 through the apparatus 1000 along the process direction X. Thereby the apparatus 1000 is a pultrusion-like apparatus 1000 for manufacturing pre-formed root-end components 10 in a pultrusion-like process.

[0208] The pulling system may pass the continuous strand 500 continuously through the apparatus 1000 without stopping or pass the continuous strand 500 stepwise through the apparatus 1000, where the continuous strand is retained in each module for a period of time. The pulling system may be configured for passing the continuous strand 500 through the apparatus 1000 a speed of 4-25 meter per hour or preferably 6-12 meter per hour.

[0209] In an embodiment, the apparatus may further comprise a cutting system 1600 for cutting the pre-formed continuous root-end sequence 400 along a first cutting line 20 arranged between the two successive bushings 110 and along a second cutting line 30 arranged through the core 120, thereby providing a pre-formed root-end component 10. The cutting system 1600 may be configured for cutting the pre-formed continuous root-end sequence along a first cutting line 20 perpendicular to the process direction X and along the second cutting line 30 being angled relative to the process direction X, where the angle of the second cutting line 30 relative to the process direction X is 2-12 degrees or preferable 3-6 degrees. Thereby providing a chamfered pre-formed root-end component 10.

[0210] In an embodiment, the loading module 1100 may further load a spacer 130 arranged between the two successive bushings 110, wherein the first cutting line 20 may be arranged through a spacer 130, wherein the spacer 130 helps localizing the first cutting line 20 in the cutting module 1600.

[0211] The apparatus 1000, thereby, provides pre-formed root-end components 10 that can be arranged in the root region of a wind turbine such that a plurality of the pre-formed rootend components 10 follow a circumference of the root region cross section, wherein a lateral face 16 of the pre-formed root end components 10 engages a lateral face 16 of an adjacent pre-formed root-end component 10. The assembly of pre-formed root-end components arranged in a root region may be subjected to a resin infusion simultaneously with the resin infusion if the wind turbine blade shell mould, thereby providing a root region with a reduced the number of bonding interfaces significantly increasing the fatigue-resistance of the root region, which is capable of withstanding the loads from the wind turbine blade on the blade -hub connection.

Claims

CLAIMS1. Method for manufacturing a pre-formed root-end component (10) for a wind turbine blade, the method comprises steps of: providing a continuous root-end sequence, the continuous root-end sequence comprises repeats of two successive bushings (110) followed by a core (120) arranged along a process direction (X); wrapping a first layer (210) comprising one or more layers of reinforcement material around the continuous root-end sequence, thereby forming a wrapped continuous root-end sequence; and either embedding the wrapped continuous root-end sequence in a second layer (310) comprising roving with a binding agent, thereby forming an embedded continuous root-end sequence; and passing the embedded continuous root-end sequence through a heated die (1500) along the process direction (X) to consolidate the roving and binding agent into a pre-formed continuous root-end sequence (400), or embedding the wrapped continuous root-end sequence in a second layer (310) comprising roving; thereby forming an embedded continuous rootend sequence; wrapping a third layer (610) comprising one or more layers of reinforcement material with a binding agent around the embedded continuous root-end sequence, thereby forming a covered continuous root-end sequence (610); and passing the covered continuous root-end sequence through a heated die (1500) along the process direction (X) to consolidate the third layer (610) into a pre-formed continuous root-end sequence (400).

2. A method according to claim 1, wherein the two successive bushings (110) are metal bushings.

3. A method according to claims 1 or 2, wherein the core (120) is made of preformed unidirectional (UD) fabric or UD roving or texturized glass roving or texturized glass fabric or thermoplastic foam or glass fibre reinforced polymer.

4. A method according to any one of the proceeding claims, wherein the core (120) and the two successive bushings (110) have the same diameter.

5. A method according to any of claims 1 to 3, wherein the two successive bushings (110) are conical bushings.

6. A method according to any one of the proceeding claims, wherein a spacer (130) is provided between the two successive bushings (110).

7. A method according to any one of the proceeding claims, wherein the method comprises a step of applying adhesive or glue to an exterior surface of the two successive bushings (110) before and / or after the step of providing or applying adhesive or glue to the reinforcement material before the step of wrapping.

8. A method according to claim 7, wherein the adhesive or glue is applied with an adhesive layer thickness of 0.5-10 mm or preferably 2-5 mm or 0.1-5 mm or 0.1- 0.5 mm or preferably 0.2-0.4 mm or more preferably about 0.3 mm.

9. A method according to any one of the proceeding claims, wherein the reinforcement material is fabrics or roving or mats, and wherein the fabrics, roving, or mats are made of glass, fibreglass, carbon, carbon fibres, UD glass, or texturized glass.

10. A method according to any one of the preceding claims, wherein the step of wrapping the first layer (210) comprises:- a step of winding filamentary reinforcement material around the continuous root-end sequence, or- a step of folding fabrics or mats of reinforcement material around the continuous root-end sequence and / or wherein the step of wrapping the third layer (610) comprises:- a step of winding filamentary reinforcement material around the embeddedcontinuous root-end sequence, or- a step of folding fabrics or mats of reinforcement material around the embedded continuous root-end sequence.

11. A method according to claim 10, wherein filamentary reinforcement material are narrow reinforcement material stripes having a width of 2-10 cm.

12. A method according to any one of the preceding claims, wherein the second layer (310) of roving with a binding agent are UD glass roving and / or texturized glass roving.

13. A method according to any one of the preceding claims, wherein roving comprises 1 to 10% or 1 to 7% or preferably 1 to 5% binding agent or the third layer (610) of one or more layers of reinforcement material comprises 1 to 10% or 1 to 7% or preferably 1 to 5% binding agent.

14. A method according to any one of the preceding claims, wherein the binding agent is a thermosetting polymer, a thermoplastic polymer, an adhesive, epoxy resin, vinyl ester, a polyester thermosetting plastic, phenol formaldehyde resin, a thermoplastic powder binder, a thermoplastic resin, a thermoplastic resin system, or any combination thereof.

15. A method according to any one of the preceding claims, wherein the method comprises a step of applying binding agent to the roving prior to the step of embedding or a step of applying binding agent to the third layer (610) of one or more layers of reinforcement material prior to the step of wrapping.

16. A method according to any one of the preceding claims, wherein the heated die (1500) heats the second layer (310) of roving and binding agent or the third layer (610) of one or more layers of reinforcement material and binding agent to a temperature of 70-180°C or 80-120°C or 90-110°C or preferably about 100°C.

17. A method according to any one of the preceding claims, wherein the embedded continuous root-end sequence or the covered continuous root-end sequence ispassed through the heated die (1500) at a speed of 4-25 meter per hour or preferably 6-12 meters per hour.

18. A method according to any one of the preceding claims, wherein after the step of passing the method comprises a step of cutting the pre-formed continuous rootend sequence (400) along a first cutting line (20) arranged between the two successive bushings (110) and along a second cutting line (30) arranged through the core (120) thereby providing a pre-formed root-end component (10).

19. A method according to claim 18, wherein the first cutting line (20) is perpendicular to the process direction (X) and the second cutting line (30) is angled relative to the process direction (X), where the angle of the second cutting line (30) relative to the process direction (X) is 2-12 degrees or preferable 3-6 degrees.

20. A method according to any one of the preceding claims, wherein pre-formed continuous root-end sequence (400) has a cross-sectional geometry comprising a substantially circular continuous root-end sequence surrounded by a substantially circular first layer (210), surrounded by: a second layer (310) having a substantially square shape or a substantially rectangular shape, or a second layer (310) having two substantially rectangular parts being displaced relative to each other, or a second layer (310) having three substantially rectangular parts, where a middle rectangular part is arranged between a top and a bottom rectangular part, and the middle rectangular part is displaced relative to the top and the bottom rectangular part.

21. A method according to claim 20, wherein the pre-formed continuous root-end sequence (400) has a cross-section size of 6-18 cm in height and 6-18 cm in width.

22. A method according to any one of the preceding claims, wherein the method comprises a step of infusing resin into the first layer (110) and second layer (310), and optionally the core (120) of- the pre-formed continuous root-end sequence (400), or- the pre-formed root-end component (10), or- an assembly of pre-formed root-end components (10) arranged in a root region of a blade shell structure.

23. A method according to any one of claims 1 to 21, wherein the method comprises a step of infusing resin into the first layer (110), the second layer (310), and the third layer (610), and optionally the core (120) of:- the pre-formed continuous root-end sequence (400), or- the pre-formed root-end component (10), or- an assembly of pre-formed root-end components (10) arranged in a root region of a blade shell structure.

24. A method according to claims 22 or 23, wherein the method comprises a step of sealing an exterior first end (12) of the bushings (110) arranged opposite to the core (120) before the step of infusing.

25. A method according to any one of the preceding claims, wherein at least one bushing (110) comprises one, two, three, or more holes.

26. A method according to any one of the preceding claims, wherein the continuous root-end sequence, the wrapped continuous root-end sequence, the embedded continuous root-end sequence, and the pre-formed continuous root-end sequence (400) forms a continuous strand (500) along the process direction (X), or wherein the continuous root-end sequence, the wrapped continuous root-end sequence, the embedded continuous root-end sequence, the covered continuous root-end sequence, and the pre-formed continuous root-end sequence (400) forms a continuous strand (500) along the process direction (X), the continuous strand (500) being continuously guided along the process direction (X) or being guided step- wise along the process direction (X).

27. A continuous strand (500) for manufacturing a root-end component (10) for a wind turbine blade, the continuous strand (500) comprising successively along a process direction (X):a continuous root-end sequence, the continuous root-end sequence comprises repeats of two successive bushings (110) followed by a core (120) arranged along the process direction (X); a wrapped continuous root-end sequence, where a first layer (210) comprising one or more layers of reinforcement material is wrapped around the continuous root-end sequence; and either an embedded continuous root-end sequence, where the wrapped continuous root-end sequence is embedded in a second layer (310) comprising roving with a binding agent; and a pre-formed continuous root-end sequence (400), where the roving and binding agent of the embedded continuous root-end sequence is consolidated, or an embedded continuous root-end sequence, where the wrapped continuous root-end sequence is embedded in a second layer (310) comprising roving; a covered continuous root-end sequence, where the embedded continuous root-end sequence is wrapped in a third layer (610) comprising one or more layers of reinforcement material with a binding agent; and a pre-formed continuous root-end sequence (400), where the roving and binding agent of the covered continuous root-end sequence is consolidated.

28. A continuous root-end sequence for manufacturing a root-end component (10) for a wind turbine blade, the continuous root-end sequence comprises repeats of two successive bushings (110) followed by a core (120) arranged along a process direction (X).

29. A wrapped continuous root-end sequence for manufacturing a root-end component (10) for a wind turbine blade, the wrapped continuous root-end sequence comprises: a continuous root-end sequence comprising repeats of two successive bushings (110) followed by a core (120) arranged along a process direction (X), anda first layer (210) comprising one or more layers of reinforcement material wrapped around the continuous root-end sequence.

30. An embedded continuous root-end sequence for manufacturing a root-end component (10) for a wind turbine blade, the embedded continuous root-end sequence comprises: a continuous root-end sequence comprising repeats of two successive bushings (110) followed by a core (120) arranged along a process direction (X), a first layer (210) comprising one or more layers of reinforcement material wrapped around the continuous root-end sequence, and a second layer (310) comprising roving with or without binding agent embedding the first layer (210) of reinforcement material.

31. A covered continuous root-end sequence for manufacturing a root-end component (10) for a wind turbine blade, the embedded continuous root-end sequence comprises: a continuous root-end sequence comprising repeats of two successive bushings (110) followed by a core (120) arranged along a process direction (X), a first layer (210) comprising one or more layers of reinforcement material wrapped around the continuous root-end sequence, a second layer (310) comprising roving embedding the first layer (210) of reinforcement material, and a third layer (610) comprising one or more layers of reinforcement material with a binding agent wrapped around the second layer (310) of roving.

32. A pre-formed continuous root-end sequence (400) for manufacturing a root-end component (10) for a wind turbine blade, the pre-formed continuous root-end sequence (400) comprises: a continuous root-end sequence comprising repeats of two successive bushings (110) followed by a core (120) arranged along a process direction (X),a first layer (210) comprising one or more layers of reinforcement material wrapped around the continuous root-end sequence, and either a second layer (310) comprising roving with binding agent embedding the first layer (210), wherein the roving and binding agent are consolidated or a second layer (310) comprising roving embedding the first layer (210) of reinforcement material, and a third layer (610) comprising one or more layers of reinforcement material with a binding agent wrapped around the second layer (310) of roving, wherein the third layer (610) is consolidated.

33. A pre-formed root-end component (10) for a wind turbine blade, wherein the root-end component (10) comprises: a bushing (110) having a first end (12), and a second end (14); a core (120) arranged adjacent to the second end (14) of the bushing (110); a first layer (210) comprising one or more layers of reinforcement material covering an exterior surface of the bushing (110) and the core (120); and either a second layer (310) comprising roving with a binding agent surrounding the first layer (210); wherein the second layer is consolidated into a pre-form, or a second layer (310) comprising roving surrounding the first layer (210); and a third layer (610) comprising one or more layers of reinforcement material with a binding agent wrapped around the second layer (310), wherein the third layer (610) is consolidated inro a pre-from.

34. A wind turbine blade comprising a blade shell structure (2000) comprising a root region for attachment to a rotor hub, wherein a plurality of pre-formed root-end components (10) according to claim 33 being arranged for securing the wind turbine blade to the rotor hub are arranged in the root region such that the pluralityof pre-formed root-end components (10) follow a circumference of the root region cross section, and wherein a lateral face (20) of the pre-formed root end components (10) engages a lateral face (20) of an adjacent pre-formed root-end component (10).

35. A wind turbine blade according to claim 34, wherein an intermediate layer (700) with 20-65% out of plane glass fibre filaments is arranged between adjacent preformed root-end components (10) and engaging the lateral faces (20) of adjacent pre-formed root-end components (10).

36. A method for manufacturing a wind turbine blade, the method comprises steps of: providing a blade shell structure (2000) comprising a root region for attachment to a rotor hub; manufacturing a plurality of pre-formed root-end components (10) according to a method of any of claims 1-26 or providing a plurality of pre-formed root-end components according to claim 33, wherein the pre-formed root-end components (10) are arranged for securing the wind turbine blade to the rotor hub; arranging the plurality of pre-formed root-end components (10) in the root region such that the plurality of pre-formed root-end components (10) follow a circumference of the root region cross section, and a lateral face (20) of the pre-formed root end components (10) engages a lateral face (20) of an adjacent pre-formed root-end component (10), thereby providing a root region assembly; infusing a resin into the root region assembly, and curing the resin for fixing the plurality of pre-formed root-end components (10) within the root region of the blade shell structure (2000).

37. A method according to claim 36, wherein the method, prior to the step of infusing, comprises a step of arranging an intermediate layer (700) with 20-65% out of plane glass fibre filaments between adjacent pre-formed root-end components(10) such that the intermediate layer (700) engages the lateral faces (20) of adjacent pre-formed root-end components (10).

38. An apparatus (1000) for manufacturing a preformed root-end component (10) for a wind turbine blade, the apparatus (1000) comprising: a loading module (1100) for loading repeats of two successive bushing (110) followed by a core (120) along a process direction (X), thereby providing a continuous root-end sequence; a wrapping module (1300) for wrapping the continuous root-end sequence in a first layer (210) comprising one or more layers of reinforcement material, thereby providing a wrapped continuous root-end sequence; and either an embedding module (1400) for embedding the wrapped continuous root-end sequence in a second layer (310) comprising roving with a binding agent along the process direction (X), thereby providing an embedded continuous root-end sequence; or an embedding module (1400) for embedding the wrapped continuous root-end sequence in a second layer (310) comprising roving along the process direction (X), thereby providing an embedded continuous rootend sequence; and a second wrapping module (1350) for wrapping the embedded continuous root-end sequence in a third layer (610) comprising one or more layers of reinforcement material with a binding agent along the process direction (X), thereby providing a covered continuous root-end sequence; and a heated die (1500) for consolidating the roving and binding agent or the third layer (610) to a pre-formed continuous root-end sequence (400) along the process direction (X); and a pulling system for continuously or stepwise passing a continuous strand (500) comprising successively along the process direction (X): the continuous root-end sequence, the wrapped continuous root-end sequence, the embedded continuous root-end sequence, and the preformed continuous root-end sequence (400), orthe continuous root-end sequence, the wrapped continuous root-end sequence, the embedded continuous root-end sequence, the covered rootend sequence, and the pre-formed continuous root-end sequence (400), through the apparatus (1000) along the process direction (X).

39. An apparatus (1000) according to claim 38, wherein the apparatus (1000) comprises an adhesive application (1200) module for applying adhesive or glue to an exterior surface of the bushings (110) or to the one or more layers of reinforcement material of the second layer (210) of before wrapping.

40. An apparatus (1000) according to claims 38 or 39, wherein the apparatus (1000) comprises a cutting system (1600) for cutting the pre-formed continuous rootend sequence (400) along a first cutting line (20) arranged between the two successive bushings (110) and along a second cutting line (30) arranged through the core (120), thereby providing a pre-formed root-end component (10).

41. An apparatus (1000) according to any one of claims 38 to 40, wherein the apparatus (1000) comprises a binding agent feed module arranged prior to the embedding module (1400) or the second wrapping module (1350), the binding agent feed module being configured for applying binding agent to the roving prior to embedding or to the one or more layers of reinforcement material of the third layer (610) prior to wrapping.

Images