DK201570772A1 - Tool and method for fabricating shear webs for a wind turbine blade - Google Patents

Abstract

A mould tool for fabricating webs for a wind turbine blade, the mould tool comprising a first mould bed for fabricating a first shear web and a second mould bed for fabricating a second shear web. Advantageously, at least two shear webs can be fabricated on the same mould tool. This results in the fabrication process taking up much less factory floor space which improves the efficiency of the manufacturing process and reduces costs. Embodiments of the invention also provide a method of fabricating shear webs for a wind turbine blade, comprising fabricating a first shear web on a first mould bed of a mould tool, and fabricating a second shear web on a second mould bed of the mould tool.

Description

TOOL AND METHOD FOR FABRICATING SHEAR WEBS FOR A WIND TURBINE BLADE

TECHNICAL FIELD

The invention relates to a mould tool for fabricating shear webs of wind turbine blades and also to a method of manufacture of such shear webs.

BACKGROUND A modern utility-scale wind turbine blade comprises a structural beam that in some designs is formed from a two-part hollow shell. The blade is stiffened to prevent it from bending excessively and, usually, each shell incorporates one or more relatively stiff spar caps that run along the length of the blade shells. To provide the blade with the necessary strength to withstand the shear forces acting on it during operation, the opposing spar caps are interconnected by a construction called a shear web. Often, a shear web is shaped in the manner of an I-beam, in which the lateral flanges of the beam are bonded to opposed interior surfaces of the blade shell, preferably, at respective opposing spar caps. A shear web is typically fabricated from composite material involving a process in which the shear web structure is laid up on a specially shaped mould surface or ‘bed’ defined by a suitable mould tool. Once the shear web lay-up has been arranged on the mould bed, it may then be bagged, resin-infused, and heat-cured to form the finished article. Since the length of a typical shear web is usually limited to around 10 metres, many such shear webs need to be fabricated for full installation into a blade. It will be appreciated, therefore, that the fabrication of such shear webs is a manually intensive process which is time consuming but which also takes up a lot of space on the factory floor. It is against this background that the invention has been devised.

SUMMARY OF THE INVENTION

In one aspect, embodiments of the invention provide a mould tool for fabricating webs for a wind turbine blade, the mould tool comprising a first mould bed for fabricating a first shear web and a second mould bed for fabricating a second shear web. In accordance with this aspect of the invention, the mould tool comprising the first and second mould beds is a single tool comprising both moulds.

An advantage of the invention is that at least two shear webs can be fabricated on the same mould tool. This results in the fabrication process taking up much less factory floor space which improves the efficiency of the manufacturing process and reduces costs.

In some embodiments, the first mould bed and the second mould bed are substantially identical. In this context, the term “identical” may include mould beds for shear webs which are paired for placement side-by-side in a mould shell. This may in particular provide a convenient means for making shear webs which are to be coextensive within the shells of a blade.

In some embodiments, the first and second mould beds may extend along respective longitudinal axes. Optionally, the mould beds may be parallel or substantially parallel with a longitudinal axis of the mould tool. In this context, the term parallel may encompass small degrees of convergence, depending on individual blade design. In such a configuration, the mould beds may be arranged in a radial spacing about the longitudinal axis of the mould tool. Although not essential, the radial spacing may be such that the mould tool is substantially rotationally or radially symmetric. For example, the mould tool may have two-fold, three-fold or four-fold symmetry.

In some embodiments, the mould tool may be rotatably mounted in a support. The support may be configured so that the mould tool can be rotated manually, for example by being mounted on a passive bearing, or by a suitable manually-operated mechanism. Alternatively, the support may be configured to provide powered rotation of the mould tool, for example by electric or hydraulic means.

Optionally, the shear webs may be cured in situ on the mould tool and, in such implementations, the mould tool may include suitable heating means arranged to heat the first and second mould beds. Mould heating means are known per se and may include any suitable heating elements. For example, heating elements may include fluid flow channels for passing heating fluids such as hot air or hot liquid, or electrical resistance heating elements or equivalents.

In some embodiments, the mould tool may be configured so that the first mould bed and the second mould bed are suitably spaced and oriented to one another such that respective shear webs are fabricated on them, the webs are supported in a fixed positional relationship which corresponds to the required position of the shear webs when located in a wind turbine blade.

Optionally, a suitable removal device may be provided, to engage the shear webs on opposite sides of a mould tool in a predetermined reference position, and lift the shear webs away from the mould tool. Subsequently, the removal device may be configured to return the shear webs to the predetermined reference position ready for positioning the first and second shear webs in a wind turbine blade.

In another aspect, embodiments of the invention provide a method of fabricating shear webs for a wind turbine blade, comprising fabricating a first shear web on a first mould bed of a mould tool, and fabricating a second shear web on a second mould bed of the mould tool. In some embodiments, the first shear web may be fabricated before the second shear web. Optionally, either of the first or second shear webs may undergo a curing process before the other shear web. Alternatively, the first and second shear webs may undergo a curing process at the same time.

The mould tool may be rotated so as to provide selective access to either of the first and second mould beds. In some embodiments, the mould tool may be rotated one the shear webs have been fabricated so as to orient the shear webs into a predetermined orientation for a curing process.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a chord-wise cross-section of a wind turbine blade which illustrates the location and orientation of structural components such as spar caps and shear webs;

Figure 2 is a schematic cross section view of a mould tool illustrating how a typical shear web is fabricated;

Figure 3 is a perspective view of a mould tool in accordance with an embodiment of the invention;

Figure 4 is a schematic side view of the mould tool in Figure 3;

Figures 5a to 5e are a series of view illustrating a fabrication process of two shear webs using the mould tool and the installation of the shear webs into a blade shell;

Figures 6a and 6b are schematic views of a complementary pair of shear webs being removed from a mould tool by a removal and handling device (Figure 6a) and installed in a blade shell (Figure 6b); and

Figure 7 is a schematic view in cross section of a mould tool in accordance with an alternative embodiment.

DETAILED DESCRIPTION

The invention concerns techniques for fabricating shear webs for wind turbine blades, and also techniques for installing those shear webs into an associated blade structure. Before discussing the fabrication techniques in detail, a brief discussion of wind turbine blade structures now follows in order to put the invention into context.

With reference firstly to Figure 1, a wind turbine blade 10 typically has a hollow shell structure comprising an upper half shell 12 and a lower half shell 14 that are united to form the complete shell having an aerofoil cross section. Each half shell may be a composite structure comprising inner and outer laminate layers or ‘skins’ 20,22 of material, for example fibre reinforced plastic (FRP).

The upper and lower half shells 12,14 may each include a strengthening structure 24 comprising two spar caps 26, each of which runs along a substantial portion of the spanwise length of the blade 2 from the blade root towards the blade tip. The spar caps 26 may also be known by other terminology in the. It is preferable for the spar caps 26 to have high tensile strength, preferably being stiff and lightweight and for this reason they may be fabricated from infused stacks of carbon fibre pultruded strips that are bonded to the outer blade skin 22 by a suitable engineering adhesive. Carbon fibre is not essential, however, but is generally preferred due to its very high strength to weight ratio. In the illustrated blade 10, the spar caps 26 are shown embedded in the laminated FRP layers and so form an integral part of the shells 12,14. Such a blade design is sometimes referred to as a ‘structural shell’. In alternative blade designs, the blade stiffness may be imparted to the shells via a longitudinal spar in the shape of a box beam, tapered along its length. Such a spar may itself incorporate the stiff spar caps, to which the blade shell may be bonded. Certain regions of the blade preferably incorporate lightweight cores 18 such as structural foam or balsa wood that are sandwiched between the outer and inner skins 20,22 and located in between the spar caps 26. Such a ‘sandwich panel’ construction improves bending stiffness and reduces the risk of buckling in these regions. Similar blade structures are also known having a single spar cap in each shell.

To provide the blade with the necessary strength to withstand the shear forces acting on it during operation, the opposing spar caps 26 may be interconnected by a construction called a shear web 32. Two shear webs 62 are shown in Figure 1, each of which is connected between a respective pair of spar caps 26. It will be noted that each of the shear webs 32 is shaped like an I-beam, in which lateral flanges 32a are bonded to opposed spar caps 26, although different configurations would be known to the skilled person, such as a C-shaped shear web, possibly incorporating return flanges.

Whereas Figure 1 shows a cross section view of an entire fabricated blade, Figure 2 shows a cross-section through a shear web 32 of the blade during an exemplary fabrication process.

The shear web 32 is supported on a mould surface or ‘bed’ 40 defined by a mould tool 42. The mould tool 42 is typically mounted on a factory floor or a raised work surface to allow a suitably skilled personnel to work with the mould tool 42.

The illustrated mould bed 40 has a raised central region 44 which may be provided by a raised central block-like structure or an integral profiled portion of the mould tool 42. The raised central region 44 helps to impart top and bottom flanges to a shear web, thereby creating a C-beam cross section shear web. A more stable I-beam web may be generated for example by applying return flanges to the reverse side top and bottom of a C-beam web in a post-curing process step. Alternatively, optionally, an I-beam web may be made directly in an adapted, raised type mould as shown in Fig. 2.

In Figure 2 the shear web 32 is shown in the form of a lay-up that has been prepared on the mould tool 42. As can be seen, the shear web 32 comprises several components that are laid up on the mould tool in a step by step process before they are consolidated by the curing process. The laying up process for constructing the shear web 32 will now be described briefly for clarity, although it should be noted that the specific process steps are not considered part of the inventive concept.

Firstly, a first fabric layer 46 may be placed on the raised central region 44 such that side portions of the first fabric layer hang down the sides of the raised central region 44 so as to form some flanges of the shear web. On top of the first fabric layer 46 may be placed a slim structural core 48, for example of structural foam, which provides thickness and lends strength to the main web 32b of the shear web 32. A second fabric layer 52 may be laid on top of the first fabric layer 46 and the core 48, and configured such that side edges of the second fabric layer 52 terminate at edges of the raised portion 44. So, the illustrated completed shear web lay-up is formed by the two fabric layers 46 and 52 and the intermediate core 48.

The shear web lay-up may then be covered by a vacuum bagging film 56 from which air is removed, following which the lay-up is subjected to a resin infusion and/or curing process. The fabric layers may either be dry fabric layers, for example of glass fibre or may alternatively be pre-impregnated with resin, known as ‘pre-preg’. If dry fabric layers are used the lay-up must be impregnated with resin before the entire assembly is heated to cure it. Alternatively, if pre-preg fabrics are used, then the lay-up simply needs to be heated in order to consolidate the individual components into a finished shear web. The general process of resin infusion and curing a composite lay-up structure is known and a full explanation will not be provided here for reasons of brevity.

For the purposes of curing the lay-up, heating of the mould tool may be achieved by heating elements 58 integrated into the mould tool 42. The heating elements 58 may be resistive heating elements controlled by a suitable electric heating system, or may be conduits for blown hot air or a different suitable fluid.

Once the illustrated shear web lay-up has been cured, the result is a completed shear web having a C-beam cross section. One way in which this may be converted into an I-beam cross section is to affix return flanges 50 onto the edges of the second fabric layer 52.

The mould tool 42 depicted in Figure 2 includes a single mould bed 40. As a result the mould tool can be used to fabricate a single shear web at any one time. In order to fabricate more than one shear web at the same time, more than one mould tool would need to be arranged next to one another. This takes up factory floor space and also requires a higher number of skilled operatives to lay up the moulds, as well as multiplying the energy usage to power the heating systems for the moulds.

An aspect of the invention relates to a mould tool for fabricating shear webs for wind turbine blades which mitigates at least some of the issues mentioned above and, in particular, realises a reduction of floor space for producing multiple shear webs, and also provides efficiencies in terms of energy usage for the curing processes implemented by such mould tools. In a broad sense, the mould tool includes a first mould bed for fabricating a first web and a second mould bed for fabricating a second web. At least two shear webs can therefore be fabricated on the same mould tool.

In one embodiment, the mould tool is double-sided, in that a first web is supportable on a first mould bed defined by a first side of the mould tool, and a second web is supportable on a second mould bed. Other embodiments are envisaged, however, in which more than two mould beds could be defined by a single mould tool.

Each of the mould beds may extend generally along a longitudinal axis, consistent with the elongate shape of the respective shear webs. Each mould bed may therefore be arranged so that it is mutually parallel with one or more mould beds arranged radially around a central common longitudinal axis. In order to provide access to each of the mould beds, the tool may be configured to rotate around the central longitudinal axis, like a horizontally-oriented carousel or rotisserie. This arrangement has great spacesaving potential, which also provides a corresponding saving on production costs.

An indexing arrangement may be included so that the mould tool is rotatable through predetermined angular steps to present each mould bed at an appropriate orientation at a predetermined workstation so that can be worked on by skilled operatives. This means that those operatives can remain in one location to work on the various different mould beds as they are rotated into position, and so the operatives are not required to move about the factory floor between moulds. Each mould bed may be substantially identical, which may be particularly useful where the mould beds are used to create substantially identical shear webs. In such circumstances, the mould tool may be rotationally symmetric having an order corresponding to the number of mould beds. For example in a ‘double sided’ mould tool, the mould tool may have twofold or Ί80 degree’ rotational symmetry since both mould beds are identical and oriented ‘back to back’.

The mould tool may be configured so that the shear webs fabricated on its mould beds are in the same relative positional relationship as would be required when those shear webs are installed into a blade. This is particularly the case for a double-sided mould tool since the shear webs are substantially parallel to each other in cross section.

Apparatus may be provided to remove the fabricated shear webs from the mould tool. This may be a removal device in the form of a parallel gripper arrangement having two parallel arms each provided with an appropriate end effector or tool to grasp hold of its associated shear web. When engaging the opposed shear webs in position on the mould tool the device may adopt or define the initial relative positions as a datum or reference. Then the device may move out of the datum position to lift the shear webs from the mould tool and transport them to a blade shell for installation. On installation, the device may move the shear webs back into the datum position so that they can be placed into a blade shell in the correct spacing relative to one another. The apparatus may use suction cups configured to suction onto a planar surface of the shear web.

Figure 3 shows a specific implementation of a mould tool 60 comprising a first mould bed 62 and a second mould bed 64. Each of the mould beds 62,64 is elongate and extends along a longitudinal axis L, and so are parallel to one another. In the illustrated embodiment, the longitudinal axis L is also shared by the mould tool 60. Embodiments are envisaged which include a plurality of mould beds arranged radially about the longitudinal axis, but in this embodiment two mould beds 62,64 are opposed to one another in a ‘back-to-back’ manner.

Each mould bed 62,64 defines a respective mould surface 66,68 that is configured with a profile for the lay-up of a respective shear web. The lay-up process on each of the mould beds 62,64 may be the same as the process described above in respect of Figure 2, so will not be explained again here. In Figure 2, however, it will be noted that each of the mould beds 62,64 supports a completed lay-up of a shear web, which are shown here labelled as 69.

The first mould surface 66 may have an identical profile to the second mould surface 68 so that substantially identical shear webs 69 can be fabricated on them. The profile of each of the mould surfaces 66,68 may be substantially the same as that in Figure 2, such that the shear webs fabricated on the mould surfaces 66,68 have either an approximate C-beam or I-beam structure; an I-beam structure is shown in the illustrated embodiment.

In the embodiment shown in Figure 3, the mould tool 60 can be considered to be double-sided in that the first mould bed 62 is opposed to the second mould bed 64. As such, each of the mould beds 62,64 may be mirror images about a lateral plane ‘A’ taken horizontally through the centre of the mould tool 60, when viewed in the orientation in Figure 3. Expressed another way, the mould tool 60 may be two-fold or 180 degrees rotationally symmetric.

In order for access to be provided selectively to either the first or the second mould beds 62,64, the mould tool 60 is preferably rotatable. This is depicted in Figure 4, in which the mould tool 60 is shown rotatably mounted on a support 75. In this embodiment the support 75 may comprise two bearings 76 located at either end of the mould tool 60. By way of example, one of the bearings 76 may comprise a drive unit 70 which is configured to rotate the mould tool 60 about its longitudinal axis L. The drive unit 70 may be any suitable actuator such as an electric or hydraulic motor linked to a suitable transmission to drive the mould tool 70 at an appropriate speed. Alternatively the mould tool 60 could be rotated in the support 75 manually. An indexing arrangement may be provided by a suitable drive control system 72 in order to operate the drive unit 70 so that the mould tool 60 rotates in fixed angular increments. For example, the mould tool of Figure 3 could be rotated through angular increments of 180 degrees or less.

The mould tool 60 may be made from any suitable material that provides a stable base for the fabrication of composite parts. It is envisaged that steel would be suitable, but other material could also be used such as aluminium or wood, or the mould tool could also be a composite structure. Heating means may be provided to increase the surface temperature of the mould tool 60 during a curing process. The heating means could be an arrangement in the form of electric heating elements integrated into the structure of the mould tool 60, and which are indicated in Figure 3 by the label ‘74’, only two of which are labelled for clarity. Other heating means could, of course, be provided, for example a heated liquid may be circulated through the mould tool using suitable ducting, or a blown air system would also be suitable.

Figure 5a to 5e show an exemplary shear web fabrication and installation process. At step 100, shown in Figure 5a, the mould tool 60 is held in a horizontal orientation such that one of the mould beds 62 faces upwards. A first shear web lay-up 102 is then fabricated on the mould bed 62. Although not shown in step 100, the shear web lay-up 102 may also be prepared for resin infusion and curing at this point.

Once the shear web layup 102 has been fabricated on the first mould bed 62, the mould tool 60 is then rotated through e.g. 180 degrees or until the second mould bed 64 faces upwards, as shown in step 104 at Figure 5b. A second shear web lay-up 106 is then fabricated on the exposed second mould bed 64. Once again, the shear web layup 106 may be prepared for the resin infusion and curing process at this point, although it is not shown in the diagram. Once both shear web lay-ups 102,106 are ready for the final stage of fabrication, the mould tool 60 may optionally be rotated by a further 90 degrees so that the web portions 110 of the shear webs 102,106 are located vertically, and substantially in parallel, as is shown at step 112 in Figure 5c. In this position, the shear web lay-ups may be infused with resin, if appropriate to the specific fabrication process being used, and then cured in order to consolidate the components of the shear web lay-ups 102,106 into completed shear webs 120,122. Alternatively, the shear webs may be cured at any angle of the twin-mould bed.

Notably, in aspects of the invention, the mould tool 60 may be configured so that the shear web lay-ups 102,106 are fabricated in the same relative positional relationship that is required when the completed shear webs are installed in the blade. Figure 5d shows the completed shear webs 120,122 isolated from the mould tool 60 but still in the vertical orientation as shown in Figure 5c. Figure 5e shows the shear webs 120,122 in the same relative positional relationship, but installed into a lower blade shell 130. Here it can be seen that the shear webs 120,122 are located precisely in the position in which they are required within the blade shell 130. Configuring the mould tool 60 in this way makes the process of installing the shear webs 120,122 into a blade shell 130 more straightforward since the need to install the shear webs individually is avoided, as is the need to precise relative positioning of the shear webs.

Figures 6a and 6b illustrate one example of a removal device 132 for removing the shear webs 120,122 from the mould tool 60 and installing them into a blade shell 130. The illustrated removal device 132 is configured to engage each of the first and second shear webs 120,122 when they are positioned on the mould tool 60 and to grasp them securely. Once secured, the removal device 132 is configured to lift the shear webs 120,122 away from the mould tool 60 and to transport them to a waiting blade shell at an installation station, whereupon the removal device 132 can position the shear webs 120,122 into an appropriate position in a blade shell. Optionally, a spacer may be placed between the two webs to maintain a desired separation during subsequent process steps. In other embodiments of the invention, the shear webs may be placed one-by-one in position in a mould tool, possibly with a spacer for supporting them in a predetermined spaced relationship.

In Figure 6a, the removal tool is shown engaging the shear webs 120,122. In this embodiment the removal tool 132 is in the form of a parallel gripper having two parallel arms 140,142, which extend around the tool so that free ends 140a, 142a of the arms can engage with the shear webs 120,122. The arms 140,142 are yoked at their other ends 140b, 142b and configured to pivot so that the free ends 140a, 142a, of the arms 140,142 can move away from and toward the mould tool 60 as illustrated by the arrows. Although not shown in detail in this Figure, the removal tool 132 is provided with a suitable control system such as a hydraulically driven manipulator boom and control system, labelled here schematically as ‘146’.

The free ends of the arms 140,142 carry suitable end effectors or tools 150 to grasp the shear webs 120,122 securely. One option, as shown here, is for the end tools 150 to be suction cups which are able to suction onto the essentially planar surface of the shear webs. An advantage of suction cups is that they are non-invasive as they are able to engage the shear webs without penetrating or otherwise damaging the surface of the shear webs. Suction cups aren’t essential however. Another option is that a lifting point such as a lug or hook could be formed on the surfaces of the shear webs which would cooperate with a set of jaws provided on the free ends 140a,142a of the arms.

As has been mentioned above, the mould tool 60 is may be configured so that the shear webs 120,122 are fabricated in a predetermined positional relationship which matches the required position of the shear webs 120,122 when they are installed in a blade. Therefore, when the removal tool 132 engages the shear webs 120,122 mounted on the mould tool 60, the control system 146 is able to set the position of the removal tool 132 as a reference or datum position. When the removal tool 132 lifts the shear webs 120,122 away from the mould tool 60 and transports them to an installation blade point, the tool 132 is able to return its arms 140,142 to the reference position in which the shear webs 140,142 are in the same position as when mounted on the mould tool 60. This is shown in Figure 6b.

The skilled person would be aware that various modifications could be made to the specific embodiments described above without departing from the inventive concept as defined by the claims. Some have already been noted above; others will now be described.

In some of the above embodiments, the mould beds 62,64 have been described as identical, in the sense they are mirror images of one another when oriented on the double-sided mould tool. This is because the mould tool 60 can be configured for making shear webs that have the same form. However, the skilled person would appreciate that this need not be the case and that the mould beds 62,64 may be configured with a different profile to form dissimilarly shaped shear webs.

Although the mould tool 60 has been described as being ‘double-sided’ thereby defining two mould beds, embodiments are envisaged in which a mould tool may define more than two mould beds. Figure 7 illustrates one example of this in which a mould tool 60 defines four mould beds 160. In this embodiment, each of the mould beds 160 are shown arranged so that they are mutually orthogonal to one another. Expressed another way, the mould tool 60 has four-fold or 90 degrees rotational symmetry.

Claims (15)

1. A mould tool for fabricating webs for a wind turbine blade, the mould tool comprising a first mould bed for fabricating a first shear web and a second mould bed for fabricating a second shear web.

2. The mould tool of claim 1, wherein the first mould bed and the second mould bed are substantially identical.

3. The mould tool of claim 1 or claim 2, wherein the first mould bed and the second mould bed extend along respective longitudinal axes that are substantially parallel with a longitudinal axis of the mould tool.

4. The mould tool of any preceding claim, wherein the mould tool is rotationally symmetric.

5. The mould tool of any preceding claim, wherein the mould tool is rotatably mounted in a support.

6. The mould tool of any preceding claim, including heating elements for heating the first mould bed and the second mould bed.

7. Apparatus comprising a mould tool in accordance with any preceding claim, wherein the apparatus includes a removal device configured to engage the first shear web and the second shear web on the mould tool in a predetermined reference position, and to lift the first and second shear webs from the mould tool, and to return the first and second shear webs to the predetermined reference position ready for positioning the first and second shear webs in a wind turbine blade.

8. A method of fabricating shear webs for a wind turbine blade, comprising: fabricating a first shear web on a first mould bed of a mould tool; and fabricating a second shear web on a second mould bed of the mould tool.

9. The method of claim 8, including fabricating the first shear web on the first mould bed before fabricating the second shear web.

10. The method of claim 8 or 9, including rotating the mould tool so as to provide selected access to the first mould bed or the second mould bed.

11. The method of any claim 8 to 10, wherein the mould tool is rotated once the first shear web and the second shear webs have been fabricated so as to orient said shear webs into a predetermined orientation for a curing process.

12. The method of any claim 8 to 11, including curing the first shear web and the second shear web simultaneously on the mould tool.

13. The method of any claim 8 to 12, wherein the first mould bed and the second mould bed are configured such that, when a respective first shear web and second shear web are fabricated thereon, the first and second shear webs are supported in a fixed positional relationship which corresponds to the required position of the shear webs when located in a wind turbine blade.

14. The method of any claim 8 to 13, including identifying that the first and second shear webs are in a reference positional relationship; engaging the first and second shear webs with a removal device whilst the first and second shear webs are in the reference positional relationship; removing the shear webs from the mould tool.

15. The method of claim 14, including, after removing the shear webs from the mould tool, controlling the removal device to position the shear webs in the reference positional relationship; and, installing the shear webs into a wind turbine blade.