Wind turbine blade core assembly and method for its manufacture

Abstract

There is provided a kit of parts for manufacturing at least part of a cellular core of a wind turbine blade The kit of parts includes a plurality of core sections (102, 104) composed of cellular material, each core section (102, 104) having a peripheral surface (111) which comprises a first side face (106), a second side face (108) and a third side face (110). Each core section (102, 104) has at least one hole (126) extending inwardly from at least one of first and second end faces (122, 124). The kit of parts further includes at least one dowel (130) composed of cellular material, the dowel (130) being shaped and dimensioned to fit within a respective hole of each of two adjacent core sections (102, 104) so that the at least one dowel (130) connects together the two adjacent core sections (102, 104).

Description

WIND TURBINE BLADE CORE

[0001] Introduction

[0002] The present invention relates to a kit of parts for manufacturing at least part of a cellular core of a wind turbine blade, a core assembly for a wind turbine blade, a wind turbine blade comprising the core assembly, and a method for manufacturing parts of a core assembly for a wind turbine blade.

[0003] Background

[0004] It is well known to those skilled in the art of manufacturing wind turbine blades to utilise layers of cellular material when building-up a core layer for a wind turbine blade. For example, the core layer may comprise an expanded cellular foam, for example a polymeric foam such as polyethylene terephthalate (PET) foam. Or the core layer may comprise a wood such as balsa wood.

[0005] When manufacturing large structural components, such as wind turbine blades, the core layer is disposed between dry fibrous layers, and then liquid resin, which is a thermosetting resin such as an epoxy resin, or a thermoplastic resin, is infused into the dry fibrous layers. Typically, the liquid resin is infused by a resin transfer moulding (RTM) process, such as a vacuum assisted resin transfer moulding process (VARTM), in which the structural component is manufactured in a mould. These processes are generally known to persons skilled in the art.

[0006] A known shape for a wind turbine blade 1 is shown in Figure 1. The blade 1 comprises a leading edge 9 and a trailing edge 11. The blade 1 comprises a root region 3 at a radially inner end of the blade. The root region 3 is of circular cross section and is configured to attach to a hub of a wind turbine. The blade 1 comprises an aerodynamic region 7 at a radially outer end of the blade 1. The aerodynamic region 7 has an airfoil cross section, as schematically shown in Figure 2. As shown, the airfoil section tapers gradually to the trailing edge 11 which is relatively finely pointed.

[0007] On the blade 1, a transition region 5 is located between the root 3 and the aerodynamic region 7. Together, the root region 3 and the transition region 5 are the main load bearing regions of the blade 1. A known development in wind turbine blade technology is to design the transition region 5 with a truncated or “flatback” trailing edge 11’. A flatback section is shown in cross-section in Figure 3. The flatback section may extend from a radially455881PCTouter end of the root region 3 to a maximum chord position 13 along the length of the wind turbine blade 1.

[0008] Without the flatback profile, the transition region 5 (which, as discussed above, is one of the main load-bearing structures within the blade 1) requires precise tapering of the composite layers (for example to produce the cross-sectional shape shown on Figure 2), which adds complexity. On the other hand, the flatback section can be made as a single component with constant thickness, leading to easier manufacturing, enhanced structural strength and aerodynamic performance. This may enable a longer blade that captures more energy with less material whilst being easier to manufacture.

[0009] It is known to provide sections of core structural “filler” material 15, 17 in respective corners 19, 21 of the flatback profile. This is known for example from W02018 / 015250A1. It can be seen that the corner regions 19, 21 are right angled or substantially right angled, which requires filler material having a corresponding right-angled portion (such as a right-angled triangle). Typically, this filler material is provided in relatively long length, perhaps Im or more, and milled on all sides, before being ready to be installed in the blade mould. This milling operation demands special clamping tools and is time-consuming. Also, the milling operation can lead to large amounts of wastage of material.

[0010] When laying up the lengths of core filler material in the blade mould in known processes, the lengths of core filler material are laid end to end without being securely connected to each other, which can lead to misalignment in the mould between adjacent sections of the filler material.

[0011] The present invention aims to overcome or at least mitigate some of these problems.

[0012] Summary

[0013] In a first aspect there is provided a kit of parts for manufacturing at least part of a cellular core of a wind turbine blade according to claim 1.

[0014] In a second aspect there is provided a core assembly for a wind turbine blade according to claim 16.

[0015] In a third aspect there is provided a wind turbine blade according to claim 32.

[0016] In a fourth aspect there is provided a method of manufacturing parts for a core assembly according to claim 34.

[0017] In a fifth aspect there is provided a method of constructing a core assembly according to claim 40.

[0018] Further features according to some embodiments are set-out in the dependent claims.

[0019] Brief description of drawings455881PCT

[0020] There follows a detailed description of some embodiments of the present invention with reference to the accompanying Figures, in which:

[0021] Figure 1 shows a perspective view of a known wind turbine blade;

[0022] Figure 2 is a cross-sectional view of a portion of a known wind turbine blade;

[0023] Figure 3 is a cross-sectional view of a “flatback” portion of a known wind-turbine blade;

[0024] Figure 4 is a perspective view of a known section of core material for a flatback blade portion;

[0025] Figure 5 schematically shows a plurality of core sections for a wind turbine blade, according to the invention;

[0026] Figure 6 schematically shows an assembly comprising a plurality of core sections joined together, according to the invention;

[0027] Figure 7 is a schematic “see-through” view of an assembly comprising a plurality of core sections joined together, according to the invention;

[0028] Figure 8 schematically shows a section of cellular material being milled, according to the present invention;

[0029] Figure 9 schematically shows in plan view an arrangement of milled core section, according to the present invention.

[0030] Detailed description

[0031] Figure 4 is a perspective view of a known section of core material 2, for insertion into a “flatback” portion of a blade mould. For example, the section of core material 2 may be used as filler material in the comers of the flatback section, equivalent to material 15 and 17 in Figure 3. A length LI of the section of core material may be around Im or more.Typically, a plurality of sections of core material 2 will be laid end-on-end in the blade mould without securely joining to each other, prior to an RTM or VARTM procedure.

[0032] The section of core material 2 is typically computer numerically controlled (CNC) machined into shape by on all sides by a milling tool, prior to insertion in to the blade mould. This milling operation demands special clamping tools due to the size of the piece of material. For example, dimensions of the original piece of material may be 2,440mm by 200mm. Moreover, and due to the size and clamping considerations, the known process is time-consuming. Moreover, there is substantial wastage of material. For example, material that would have been present in curved region 23 of removed material, is completely wasted.

[0033] The present invention has identified that wastage of core material, particularly in the flatback section of the wind turbine blade, can be substantially reduced by efficiently cutting455881PCTor milling out a series of smaller portions of core material from a supply piece of core material, and then joining those smaller portions together with dowels to build back-up an overall section of core material. There are further advantages that will also be apparent from the foregoing.

[0034] Figure 5 shows some parts or components of a core assembly for a wind turbine blade, according to the invention. The parts comprise a plurality of core sections 102, 104. Core section 102 may be considered a first core section and core section 104 may be considered a second core section. Of course, this is by way of example for the purpose of concise explanation and in practice there may be any number of two or more such sections 102, 104 to make up an overall core assembly. Each of the core sections 102, 104 is composed of a cellular material. For example, the cellular material may comprise a polymeric foam such as polyethylene terephthalate (PET) foam. Alternatively, the cellular material may be a lightweight wood, such as balsa wood. As will be explained in more detail below, each core section 102, 104 is cut or milled from an original piece or section of provided material of unitary construction, from which multiple sections of core material (such as core sections 102, 104) are milled out. Though not essential, it is likely that both core sections 102, 104 will have been milled from the same original section of core cellular material.

[0035] As shown in Figure 5, each core section 102, 104 has a peripheral surface 111 which comprises a first side face 106, a second side face 108 and a third side face 110. In some examples, each of the core sections 102, 104 is identical or substantially identical. Therefore for conciseness some features will be primarily described with respect to core section 102, though it will be understood that such features may be equally applicable to core section 104 (and any further core sections).

[0036] The first and second side faces 106, 108 intersect at a first edge 112. The first edge 112 is located in or on the peripheral surface 111. The first and second side faces 106, 108 are each substantially aligned with a respective first or second plane Pl, P2. It may be considered that the planes Pl, P2 are virtual planes rather than actual physical planes of the first and second side faces 106, 108. The first and second planes Pl, P2 intersect at the first edge 112 and are substantially orthogonal to each other.

[0037] In some examples one or more of the first and second side faces 106, 108 is planar or substantially planar. In such examples, a plane of first side face 106 may be the same as plane Pl and a plane of second side face 108 may be the same as plane P2.

[0038] In some examples, one or more of the first and second side faces 106, 108 is non- planar. In some examples the first and second side faces 106, 108 are milled to have a curved455881PCTor slightly curved profile. This curve may have a relatively large radius, such that from a distance the first and / or second side faces 106, 108 may still appear substantially planar. In other examples, the curve may be more pronounced. Having a non-planar surface for one or more of the first and second side faces 106, 108 may enhance conformability with a respective blade mould, and / or may aid in promoting efficient resin transfer during RTM or VARTM.

[0039] The peripheral surface 111 further comprises a second edge 114. The second edge 114 is located at a first distal end 116 of the first side face 106 that is spaced from the first edge 112. The peripheral surface 111 also comprises a third edge 118 located at a second distal end 120 of the second face 108 that is spaced from the first edge 112.

[0040] Each core section 102, 104 has opposite first and second end faces 122, 124 which are substantially parallel and substantially orthogonal to the first and second planes Pl, P2.

[0041] The third side face 110 extends between the second edge 114 and the third edge 118. The third side face 110 comprises a fourth edge 140 which interfaces with first end face 122. The third side face comprises a fifth edge 142 (hidden due to the angle of Figure 4) which interfaces with second end face 124. In examples, the third side face 110 is curved in a concave manner between the second edge 114 and the third edge 118.

[0042] Each core section 102, 104 has at least one hole 126 extending inwardly from at least one of the first and second end faces 122, 124. In some examples, the diameter of the at least one hole is between 10mm and 20mm. In some examples, the diameter of the at least one hole is 10mm. In some examples, the diameter of the at least one hole is 12mm. In some examples, the diameter of the at least one hole is 16mm.

[0043] In some examples, the at least one hole 126 comprises two or more holes on each of the first and second end faces 122, 124. In Figure 4, two holes 126, 127 on first face 124 are visible, and two or more holes 144, 146 on second end face 124 are shown in phantom.

[0044] In some examples, the at least one hole 126 comprises a through-hole extending from the first end face 122 through to the second end face 124. For example the holes shown as 126 and 144 may be the openings of a through-hole that extends the whole way through the core section 102, and similar for the holes shown at 127 and 146.

[0045] In some examples, the at least one hole 126 comprises at least one blind hole in the first end face 122 and at least one blind hole in the second end face 124. For example a milling machine may be configured to mill a short distance into the material from both end faces 122, 124 to create the blind holes. In such examples, the at least one blind hole in the first end face 122 may be axially aligned with the at least one blind hole in the second end455881PCTface 124. For example, and with respect to Figure 4, each of holes 126 and 144 may be blind holes, axially aligned along axis A-A. Likewise, each of holes 127 and 146 may be blind holes, axially aligned along axis B-B.

[0046] In examples, each hole, for example hole 126, is positioned so that with the respective core section 102, 104 positioned adjacent to at least one further core section 102, 104 with the first, second and third side faces 106, 108, 110 of the adjacent core sections 102, 104 being aligned and the first end face 122 of one of the adjacent core sections 102, 104 contacting the second end face 124 of the other of the adjacent core sections 102, 104, the respective holes 126 in the contacting first and second end faces 122, 124 are aligned with each other. For example, hole (or opening) 144 in second end face 124 of core section 102 is aligned with hole (or opening) 126 in first face 122 of core section 104.

[0047] According to some examples, there is also provided at least one dowel 130. The at least one dowel is shaped and dimensioned to fit within a respective hole of each of two adjacent core sections. This enables two adjacent core sections to be connected together. In some examples, the dowel has a diameter slightly larger than a diameter of the hole so as to be a friction fit therein. Therefore in some examples, the diameter of the dowel is between 10mm and 20mm, or slightly larger. In some examples, the diameter of the dowel is 10mm or slightly larger to correspond to a 10mm hole. In some examples, the diameter of the dowel is 12mm or slightly larger, to correspond with a 12mm hole. In some examples, the diameter of the dowel is 16mm or slightly larger, to correspond with a 16mm hole. For example, and with respect to Figure 4, dowel 130 may be a friction fit in hole or opening 144 of core section 102, and a friction fit in hole or opening 126 of core section 104. For example, the dowel 130 may be pushed into hole or opening 144 of core section 102, and then hole or opening 126 of core section 104 may be pushed onto the protruding portion of dowel 130 to join the two core sections 102, 104. In some examples there may be additional holes for receipt of additional dowels. For example, a second dowel 131 may be a friction fit in hole or opening 146 of core section 102 and in hole or opening 127 of core section 104, and so on. Having two (or more) dowel connections between adjacent core sections helps to keep those adjacent core sections aligned with each other and to prevent relative rotation therebetween, especially when being placed or positioned in a blade mould.

[0048] In some examples, where the at least one hole 126 is a through hole right through a core section 102 or 104, then a long dowel 130 may be provided that can pass right through and connect multiple core sections together. Alternatively, each at least one dowel 130 may be dimensioned or arranged to only interface with two adjacent and facing core sections.455881PCT

[0049] In some examples, two different dowel lengths are provided in a kit of parts. In some examples, a shorter dowel length is used in a first end core section, and then a longer dowel length is used to connect the subsequent core sections. For example, assume that panels are sliced into 100mm core sections. In a first or end panel a shorter (e.g. 50mm dowel) is inserted. To join subsequent panels longer (e.g. 100mm) dowels are inserted. These 100mm dowels will then be centred or almost centred in panel joints (50mm to each side). In some examples, in the last panel a dowel is inserted so that it extends to the face of the flatback. The end dowel can then be cut so that the flatback end face is smooth.

[0050] In some examples, no adhesive is added or provided to the connection between the at least one dowel 130 and the at least one hole 126. This prevents localised areas of increased stiffness occurring in the overall structure, which may otherwise occur when the adhesive hardens.

[0051] In examples, the at least one dowel is composed of cellular material. For example, the at least one dowel may comprise a polymeric material such as PET. Or, the at least one dowel may comprise a wood, such as balsa wood. In some examples, the at least one dowel 130 comprises a same cellular material as the plurality of core sections 102, 104.

[0052] In some examples, the at least one dowel has a same axial stiffness as the plurality of core sections. This helps to ensure consistent properties throughout the overall assembly (core sections plus dowels) once assembled.

[0053] However, in other examples, the at least one dowel 130 may be provided to have a different stiffness to the plurality of core sections 102, 104. By way of example only, it may in certain circumstances be desired to have a stiffer “spine” of dowels connecting adjacent core sections, for example to minimise relative movement therebetween. In such examples, the dowels may be stiffer than the core sections. For example, in such cases the dowels may comprise a denser cellular material than the plurality of core sections.

[0054] In some examples, a distance d between first face 122 and second face 124 of a respective core section 102, 104 is 100mm or about 100mm. In other words, a thickness or depth d of each core section is about 100mm. In some examples, and as described in more detail further below, each core section 102, 104 may be cut from a supply of cellular core material that is 100 mm thick or about 100mm thick. This is by way of example and other thicknesses (i.e. depth d) may be used. For example, a range of suitable thicknesses may be 5 to 200mm.

[0055] An overall cellular core assembly, comprising a plurality of separate but connected cellular core sections, is schematically shown at 150 in Figure 6. In this example, the core455881PCTassembly 150 comprises ten core sections 102, 104, 152, 154, 156, 158, 160, 162, 164, 166 joined in series. In some examples, each of these core sections in the assembly 150 has an identical or substantially identical structure. For example, the dimensions, shape, material, positioning and dimensioning of holes may be the same in each core section. In some examples, each core section is cut from a same original unitary piece of cellular material.

[0056] As previously described, adjacent core sections are connected to each other with at least one dowel 130. Figure 6 is a “see-through” or “x-ray” view of the core assembly 150 of Figure 6, which schematically shows how each pair of adjacent core sections is joined by at least one dowel 130 (or in the case of the examples of Figure 5 and Figure 6, each pair of adjacent core sections is joined by two dowels).

[0057] The core assembly 150 comprises a first end 168 and a second end 170. The core assembly 150 has an overall length L2 which extends between the first end 168 and the second end 170. In some examples, the at least one dowel 130 at end face 122 of core assembly 150 does not protrude from the end face 122. In some examples, an outer end of the at least one dowel 130 may be flush with the end face 122. For example, outwardly facing ends of first and second dowels 130, 131 are flush with end face 122, as shown in Figure 6. This may be achieved by making or providing the dowels in the end face of the core assembly of a shorter length than the dowels which are used to connect adjacent core sections, so that when the dowels are pushed into the respective end face holes the dowels do not protrude from the respective end face. Alternatively, the at least one dowel 130, 131 in end face 122 may be inserted in their corresponding holes such that a portion of each dowel protrudes from the respective at least one hole, and then the protruding portion of each dowel 130, 131 is removed, for example by a cutting operation. This may equally apply to one or more dowels on opposite end face 124 of assembly 150 at second end 170.

[0058] Arranging the dowels so that they do not protrude from the ends 168, 170 means that the dowels do not catch or snag on other components when being placed in the wind turbine blade mould. By making the outer ends of the dowels flush with the respective outer faces 122, 124 at the respective first and second ends 168, 170, the end holes are filled so as not to leave air pockets or pockets of free volume which could become filled with localised regions of resin during a resin transfer process, which could increase the weight of the overall blade.

[0059] Similarly, the length of a dowel 130 which interconnects adjacent core sections may be dimensioned so that its overall length is equal to or substantially equal to the combined length of the adjacent holes which the at least one dowel is arranged to connect. Referring back to Figure 4 for example, say hole 144 in core section 102 is a blind hole with a depth of455881PCT20mm and hole 126 in core section 104 is also a blind hole with a depth of 20mm. In such an example, the dowel 130 may have a length of 40mm, to completely fill holes 144 and 126 when the sections 102 and 104 are joined together.

[0060] Or, by way of example, if the depth d of each core section is 100mm and the at least one hole 126 is a through hole, then the at least one dowel connecting adjacent core sections may be 50mm. For connection of adjacent core sections, half of the dowel is inserted in one core section and the other half of the dowel is inserted in the adjacent core section. Within an overall core assembly 150, adjacent dowels in series may butt up against each other, again filling any free volume that was originally present in the through holes. The see-through view of Figure 7 shows this arrangement.

[0061] . Generally, it may be understood that within the overall core assembly 150, the plurality of dowels are shaped and dimensioned to together completely fill the holes into which the dowels are inserted. This may assist in avoiding undesirable air pockets or regions of free volume.

[0062] The overall length L2 of the core assembly 150 is equal to the sum of a depth d of each core section 102, 104, 152, 154, 156, 158, 160, 162, 164 and 166. For example, if depth d of each core section is 100mm, then the overall length of ten core sections when joined together is 1000mm.

[0063] In some examples, the plurality of core sections 102, 104 and at least one dowel 130 are provided as a kit of parts for manufacturing at least part of a cellular core of a wind turbine blade. For example, the kit of parts may include further components such as one or more of: dry fibre materials; prepregs; resins; adhesives; vacuum bags; infusion consumables (e.g. flow mesh, release film, peel ply, bleeder, breather) etc. The kit of parts may be provided to a wind blade manufacturer in one or more boxes or containers.

[0064] In some examples, there is also provided a wind turbine blade comprising a core assembly (e.g. core sections plus dowels) as described above.

[0065] There will now be described a method of manufacturing parts of a core assembly for a wind turbine blade, according to some examples and with further reference to Figures 7 and 8.

[0066] The method comprises (i) providing a section 172 of cellular material, such as balsa wood or polymeric foam (e.g. PET) as previously described. The section of cellular material 172 may be a unitary or monolithic section. The section of core cellular material 172 may be provided in a rectangular form in plan view. The section of cellular material 172 may have a depth d of 100mm or about 100mm. In some examples, the section of cellular material may455881PCTbe provided as raw material sheets that are 2440*1005 / 1220mm (standard raw panel size) with a thickness range of 5mm to 200mm.

[0067] In some examples, the plurality of core sections (e.g. core sections 102, 104) can be formed by 3D printing.

[0068] The section of cellular material 172 may be cut using a computer numerically controlled (CNC) cutting or milling machine shown schematically at 174. The CNC machine is programmed with a milling profile for milling a plurality of core sections 102, 104, using a milling head 176.

[0069] In other words, and with further reference to Figure 5, the method comprises (ii) milling the unitary section of cellular material 172 to provide a plurality of core sections 102, 104 composed of the cellular material, each core section 102, 104 having a peripheral surface 111 which comprises a first side face 106, a second side face 108 and a third side face 110. The first and second side faces 106, 108 intersect at a first edge 112 which is located in the peripheral surface 111 and the first and second side faces 106, 108 are each substantially aligned with a respective first or second plane Pl, P2. The first and second planes Pl, P2 intersect at the first edge 112 and are substantially orthogonal to each other. In some examples it may be considered that the first face 106 is substantially at a right angle to the second face 108. The peripheral surface 111 further comprises a second edge 114 located at a first distal end 116 of the first side face 106 that is spaced from the first edge 112 and a third edge 118 located at a second distal end 120 of the second face 108 that is spaced from the first edge 112. The third side face 110 extends between the second edge 114 and the third edge 118. Each core section 102, 104 has opposite first and second end faces 122, 124 which are substantially parallel and substantially orthogonal to the first and second planes Pl, P2. In some examples the first and second end faces 122, 124 comprise respective top and bottom surfaces of the section of cellular material 172, and in some examples no milling of those faces is required.

[0070] The method comprises milling a plurality of holes. In more detail, in some examples the method comprises (iii) milling a plurality of holes so that each core section 102, 104 has at least one hole 126 extending inwardly from at least one of the first and second end faces 122, 124. Each hole 126 is positioned so that when the respective core section 102, 104 is positioned adjacent to at least one further core section 102, 104 with the first, second and third side faces 106, 108, 110 of the adjacent core sections 102, 104 being aligned and the first end face 122 of one of the adjacent core sections 102, 104 contacting the second end face 122 of the other of the adjacent core sections 102, 104, the respective holes 126 in the455881PCTcontacting first and second end faces 122, 124 are aligned with each other. In other words, the holes are milled so that they are in a same relative spatial location on each core section 102, 104.

[0071] In some examples, step (ii) occurs before step (iii). That is an outer perimeter of each core section 102, 104 may be milled first in the section 172, and then the at least one hole 126 is milled in each core section 102, 104.

[0072] In some examples, step (iii) occurs before step (ii). That is the at least one holes 126 may be first milled in the section of material 172, and then the outer perimeter of each core section 102, 104 may be milled.

[0073] In a step (iv), the method comprises milling at least one dowel 130 composed of cellular material. The dowel 130 is shaped and dimensioned to fit within a respective hole of each of two adjacent core sections 102, 104, so that the at least one dowel 130 is configured to connect together the two adjacent core sections 102, 104.

[0074] In some examples the at least one dowel 130 is milled from the unitary section of cellular material 172. Or the at least one dowel 130 may be milled from a portion of material that originated from the unitary section of cellular material 172. For example, the at least one dowel 130 may be milled from an off-cut, such as off-cut 178. Accordingly, the at least one dowel 130 and the sections of core material 102, 104 may comprise the same material and may have the same structural composition.

[0075] In some examples, the at least one hole that is milled comprises a through-hole that extends throughout the depth d of the material 172.

[0076] The plurality of core sections 102, 104 are milled from the section of cellular material 172 in a manner and arrangement that minimises material wastage. With reference to Figure 8, in step (ii) the method may comprise milling from the section of core material 172 a first row 180 of core sections that are oriented in a first direction E and milling a second row 182 of core sections that are oriented in a second direction F. In examples, direction E is opposite to direction F. The first row 180 is adjacent to the second row 182. In plan view (such as Figure 8) in the first row 180 a respective first edge 112 of each core section points in the first direction E, and in the second row 182 a respective first edge 112 of each core section points in the second direction F. In the first row 180 each first edge 112 of each core section is linearly aligned along line C-C, and in the second row each first edge 112 of each core section is linearly aligned along line D-D. In other words, in alternating rows the orientation of core sections may be changed or flipped by 180 degrees. It may be considered that the CNC milling machine is programmed with a cutting or milling pattern that arranges the455881PCTplurality of core sections relative to each other in the section of material 172 as spaceefficient manner as possible.

[0077] It is notable that in the milling operation described with respect to Figures 7 and 8, complicated clamping tools are not required to hold the unitary section of cellular material 172 while the milling operation takes place. This is, at least in-part, due to the relatively small depth d (approx.. 100 mm in some examples) of the section 172, and the rectangular overall shape which is easy to handle.

[0078] It will be understood that embodiments of the present invention enable an overall length of the core material “spine” in the flatback to be finely and easily tuned to requirements, by adding or taking away sections or modules 102, 104 of the core material that make up the spine. In some examples, core sections 102, 104 may be connected together to create an overall long assembly that is 20m or more in length. For example, an overall length of the core assembly may be 22m or about 22m.

[0079] Also, there are significant benefits in terms of minimizing material wastage by efficient cutting of the core material sections, and complicated clamping tools are not required to hold the relatively small depth core sections in place while they are being milled.

[0080] Primarily the present application is described in the context of core assemblies for wind turbine blades. It will be understood that in other embodiments the principles described herein could be applied to the manufacture of core assemblies for other structures such as core assemblies for use in any one or more of marine; rail; automotive or construction applications. For example, in other embodiments there could be provided a kit of parts, a core assembly, and a method of manufacturing suitable for those further applications.

[0081] Various modifications to the disclosed embodiments will be apparent to those skilled in the art, and such modifications fall within the scope of the present invention as defined in the appended claims.455881PCT

Claims

Claims1. A kit of parts for manufacturing at least part of a cellular core of a wind turbine blade, the kit of parts including: a plurality of core sections composed of cellular material, each core section having a peripheral surface which comprises a first side face, a second side face and a third side face, wherein the first and second side faces intersect at a first edge which is located in the peripheral surface and the first and second side faces are each substantially aligned with a respective first or second plane, wherein the first and second planes intersect at the first edge and are substantially orthogonal to each other, the peripheral surface further comprising a second edge located at a first distal end of the first side face that is spaced from the first edge and a third edge located at a second distal end of the second face that is spaced from the first edge, the third side face extending between the second edge and the third edge; each core section having opposite first and second end faces which are substantially parallel and substantially orthogonal to the first and second planes ; each core section having at least one hole extending inwardly from at least one of the first and second end faces, each hole being positioned so that when the respective core section is positioned adjacent to at least one further core section with the first, second and third side faces of the adjacent core sections being aligned and the first end face of one of the adjacent core sections contacting the second end face of the other of the adjacent core sections , the respective holes in the contacting first and second end faces are aligned with each other; and the kit of parts further including at least one dowel composed of cellular material, the dowel being shaped and dimensioned to fit within a respective hole of each of two adjacent core sections whereby the at least one dowel connects together the two adjacent core sections .

2. A kit of parts according to claim 1, wherein the third side face is curved between the second edge and the third edge.455881PCT3. A kit of parts according to claim 1 or claim 2, wherein each of the first side face and second side face has a machined surface that is not completely planar.

4. A kit of parts according to any of claims 1 to 3, wherein the at least one hole comprises two or more holes on each of the first and second end faces.

5. A kit of parts according to any preceding claim, wherein the at least one hole comprises a through-hole extending from the first end face through to the second end face.

6. A kit of parts according to any of claims 1 to 4, wherein the at least one hole comprises at least one blind hole in the first end face and at least one blind hole in the second end face, the at least one blind hole in the first end face being axially aligned with the at least one blind hole in the second end face.

7. A kit of parts according to any of claims 1 to 6, wherein the at least one dowel comprises a same cellular material as the plurality of core sections.

8. A kit of parts according to any of claims 1 to 7, wherein the at least one dowel has a same stiffness as the plurality of core sections.

9. A kit of parts according to any of claims 1 to 8, wherein the at least one dowel has a different stiffness to the plurality of core sections.

10. A kit of parts according to any of claims 1 to 9, wherein the at least one dowel is a friction fit in the respective hole of each of each of two adjacent core sections.455881PCT1511. A kit of parts according to claim 10, wherein the friction fit is arranged to securely connect together the two adjacent core sections without adhesive.

12. A kit of parts according to any of claims 1 to 11, wherein a thickness of a respective core section between the first end face and the second end face is about 100mm.

13. A kit of parts according to any of claims 1 to 12, wherein the plurality of core sections are comprised of polymeric foam or balsa wood.

14. A kit of parts according to any of claims 1 to 13, wherein the at least one dowel is comprised of polymeric foam or balsa wood.

15. A kit of parts according to any of claims 1 to 14, further comprising any one or more of: dry fibres; a prepreg; a supply of resin; a supply of adhesive; one or more vacuum bags; infusion consumables.

16. A core assembly for a wind turbine blade, comprising: a plurality of core sections composed of cellular material, each core section having a peripheral surface which comprises a first side face, a second side face and a third side face, wherein the first and second side faces intersect at a first edge which is located in the peripheral surface and the first and second side faces are each substantially aligned with a respective first or second plane, wherein the first and second planes intersect at the first edge and are substantially orthogonal to each other, the peripheral surface further comprising a second edge located at a first distal end of the first side face that is spaced from the first edge and a third edge located at a second distal end of the second face that is spaced from the first edge, the third side face extending between the second edge and the third edge; each core section having opposite first and second end faces which are substantially parallel and substantially orthogonal to the first and second planes;455881PCT16 each core section having at least one hole extending inwardly from at least one of the first and second end faces, each hole being positioned so that with the respective core section positioned adjacent to at least one further core section with the first, second and third side faces of the adjacent core sections being aligned and the first end face of one of the adjacent core sections contacting the second end face of the other of the adjacent core sections, the respective holes in the contacting first and second end faces are aligned with each other; and at least one dowel composed of cellular material, the dowel being fitted within a respective hole of each of two adjacent core sections so that the at least one dowel connects together the two adjacent core sections.

17. A core assembly according to claim 16, wherein the third side face is curved between the second edge and the third edge.

18. A core assembly according to claim 16 or claim 17, wherein each of the first side face and second side face has a machined surface that is not completely planar.

19. A core assembly according to any of claims 16 to 18, wherein the at least one hole comprises two or more holes on each of the first and second end faces.

20. A core assembly according to any of claims 16 to 19, wherein the at least one hole comprises a through-hole extending from the first end face through to the second end face.

21. A core assembly according to any of claims 16 to 20, wherein the at least one hole comprises at least one blind hole in the first end face and at least one blind hole in the second end face, the at least one blind hole in the first end face being axially aligned with the at least one blind hole in the second end face.

22. A core assembly according to any of claims 16 to 21, wherein the at least one dowel comprises a same cellular material as the plurality of core sections.455881PCT1723. A core assembly according to any of claims 16 to 22, wherein the at least one dowel has a same stiffness as the plurality of core sections.

24. A core assembly according to any of claims 16 to 22, wherein the at least one dowel has a different stiffness to the plurality of core sections.

25. A core assembly according to any of claims 16 to 24, wherein the at least one dowel is a friction fit in the respective hole of each of each of two adjacent core sections.

26. A core assembly according to claim 25, wherein the friction fit securely connects the two adjacent core sections together without adhesive.

27. A core assembly according to any of claims 16 to 26, wherein each hole is filled by one or more of the at least one dowel, so that there is substantially no free volume in each hole.

28. A core assembly according to any of claims 16 to 27, wherein a thickness of a respective core section between the first end face and the second end face is about 100mm.

29. A core assembly according to any of claims 16 to 28, wherein the plurality of core sections are comprised of polymeric foam or balsa wood.

30. A core assembly according to any of claims 16 to 29, wherein the at least one dowel is comprised of polymeric foam or balsa wood.455881PCT1831. A core assembly according to any of claims 16 to 30, wherein the cellular core assembly is arranged for insertion into a flatback region of a wind turbine blade.

32. A wind turbine blade comprising a core assembly according to any of claims 16 to 31.

33. A wind turbine blade according to claim 32, wherein the cellular core assembly is installed in a flatback region of the wind turbine blade.

34. A method of manufacturing parts for a core assembly for a wind turbine blade, the method comprising:(i) providing a unitary section of cellular material;(ii) milling the unitary section of cellular material to provide a plurality of core sections composed of the cellular material, each core section having a peripheral surface which comprises a first side face, a second side face and a third side face, wherein the first and second side faces intersect at a first edge which is located in the peripheral surface and the first and second side faces are each substantially aligned with a respective first or second plane, wherein the first and second planes intersect at the first edge and are substantially orthogonal to each other, the peripheral surface further comprising a second edge located at a first distal end of the first side face that is spaced from the first edge and a third edge located at a second distal end of the second face that is spaced from the first edge, the third side face extending between the second edge and the third edge, and each core section having opposite first and second end faces which are substantially parallel and substantially orthogonal to the first and second planes;(iii) milling a plurality of holes so that each core section has at least one hole extending inwardly from at least one of the first and second end faces, each hole being positioned so that when the respective core section is positioned adjacent to at least one further core section with the first, second and third side faces of the adjacent core sections being aligned and the first end face of one of the adjacent core sections contacting the second end face of the other of the adjacent core sections, the respective holes in the contacting first and second end faces are aligned with each other;455881PCT19(iv) milling at least one dowel composed of cellular material, the dowel being shaped and dimensioned to fit within a respective hole of each of two adjacent core sections whereby the at least one dowel is configured to connect together the two adjacent core sections.

35. A method according to claim 34, wherein the at least one dowel is milled from the unitary section of cellular material or a portion of material that originated from the unitary section of cellular material.

36. A method according to claim 34 or claim 35, wherein in step (ii) the milling the unitary section of cellular material to provide a plurality of core sections comprises milling a first row of core sections that are oriented in a first direction and milling a second row of core sections that are oriented in a second direction that is opposite to the first direction, the first row adjacent to the second row, so that in plan view in the first row a respective first edge of each core section points in the first direction and in the second row a respective first edge of each core section points in the second direction, and in the first row each first edge of each core section is linearly aligned and in the second row each first edge of each core section in the second row is linearly aligned.

37. A method according to any of claims 34 to 36, wherein the unitary section of cellular material comprises polymeric foam or balsa wood.

38. A method according to any of claims 34 to 37, wherein the unitary section of cellular material has a thickness of about 100mm.

39. A method according to any of claims 34 to 38, wherein the unitary section of core material is provided in rectangular form.455881PCT2040. A method of constructing a core assembly for a wind turbine blade using the kit of parts according to any of claims 1 to 15, the method comprising connecting the plurality of core sections to each other with the at least one dowel.455881PCT

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