WO2021239218A1

WO2021239218A1 - Manufacturing a wind turbine blade

Info

Publication number: WO2021239218A1
Application number: PCT/EP2020/064586
Authority: WO
Inventors: Kristen HANRAHAN; Tanner KNOBLOCK; Justin HUNTER; Daniel J. Lewis; Kendall A. PASSALAQUA
Original assignee: Lm Wind Power A/S; Blade Dynamics Lllp
Priority date: 2020-05-26
Filing date: 2020-05-26
Publication date: 2021-12-02
Also published as: CN115697684A

Abstract

The invention provides a method for manufacturing a wind turbine blade shell part (24, 26). The method comprises laying up one or more outer skin fibre layers (81) in a wind turbine blade shell part mould (80); providing a spar cap part (82) comprising one or more precured elongate reinforcement elements, the spar cap part (82) having a first end (82a) and a second end (82b); gradually bringing the spar cap part (82) into contact with one or more of the outer skin fibre layers (81), starting from the first end; laying up one or more inner skin fibre layers in contact with the spar cap part; and providing liquid resin into the mould and curing the resin, thereby obtaining the wind turbine blade shell part. The invention also provides a wind turbine blade obtainable by the method.

Description

Title of the invention Manufacturing a wind turbine blade Technical field

The present invention relates to manufacturing a wind turbine blade, in particular of a type that includes one or more precured elements.

Background of the invention

Wind power is a clean and environmentally friendly source of energy. Wind turbines usually comprise a tower, generator, gearbox, nacelle, and one or more rotor blades. The wind turbine blades capture kinetic energy of wind using known airfoil principles. Modern wind turbines may have rotor blades that exceed 90 meters in length.

Wind turbine blades are usually manufactured by forming two shell parts or shell halves from layers of woven fabric or fibre and resin. Spar caps or main laminates are placed or integrated in the shell halves and may be combined with shear webs or spar beams to form structural support. Spar caps or main laminates may be joined to, or integrated within, the inside of the halves of the shell.

A number of manufacturing steps become more complicated as the blades increase in size. Any mistake made somewhere in the process is increasingly more time consuming to correct. One such process step is laying one or more precured elements on fibre layers already laid up in a blade part mould. The total length, width and weight of such elements usually increase with the size of the blade. It is therefore desirable to lay up these elements correctly the first time to avoid having to redo this step.

The present invention provides a method of arranging precured elements in a mould in an efficient and controllable way.

Summary of the invention

In a first aspect, the invention provides a method for manufacturing a wind turbine blade shell part having a tip end and a root end. The method comprises: laying up one or more outer skin fibre layers in a wind turbine blade shell part mould, providing a spar cap part comprising one or more precured reinforcement elements, the spar cap part having a first end and a second end, gradually bringing the spar cap part into contact with one or more of the outer skin fibre layers, starting from the first end, laying up one or more inner skin fibre layers in contact with the spar cap part, providing liquid resin into the mould and curing the resin, thereby obtaining the wind turbine blade shell part.

When manufacturing a wind turbine blade shell part, layers of dry fibre, such as fibre mats, are typically laid up first in a blade shell part mould. These will constitute the outer skin of the shell part. After adding the fibre layers, one or more precured elements can be added, forming a further part of the blade shell part. Spar caps are advantageously provided using this method. Adding the precured elements onto the outer skin fibre layers is tedious, and often the fibre layers get displaced or wrinkled during the process of adding the precured elements.

Embodiments of the present invention mitigate these issues. The inventors have found that adding the spar cap part starting from one end of the spar cap part and gradually bringing it into contact with the underlying fibre layers increases the precision with which the spar cap part is arranged on the fibre layers. Further, the risk of having to lift the spar cap part again, because it has not been placed in the correct position or with the correct orientation, is substantially reduced. Additionally, wrinkles in the underlying fibre layers can be handled gradually during the process. Existing methods suffer from all these issues.

In some embodiments, bringing the spar cap part into contact with one or more of the outer skin fibre layers ends with bringing the second end of the spar cap part into contact with one or more of the outer skin fibre layers.

In some embodiments, the step of bringing the spar cap part into contact with one or more of the outer skin fibre layers is initiated at a first position in the mould and ends at a second position in the mould, wherein the first position is closer to the tip end of the blade than the second position is. In other words, the first end is proximate the tip end of the shell part, and the second end is proximate the root end. The shell part is typically relatively narrow at the tip end. Embodiments of the present invention wherein the spar cap part is first brought into contact with the fibre layers in a position proximate the tip makes the process of adding the spar cap part easier.

In some embodiments, the step of gradually bringing the spar cap part into contact with one or more of the outer skin fibre layers comprises: placing the spar cap part on one or more support members arranged above the outer skin fibre layers at respective support member positions, each support member supporting the spar cap part and separating the spar cap part from the outer skin fibre layers, displacing the support members so as to gradually bring the spar cap part into contact with the outer skin fibre layers, and removing the support members from under the spar cap part.

These support members keep the spar cap part away from the fibre layers. However, it also allows personnel to work around the circumference of the spar cap part, except where the spar cap part engages with the support members. In embodiments that use one or more straps to strap non- bonded precured elements together, the support members allow personnel space to remove the one or more straps.

Some embodiments employ at least two support members.

In some embodiments, two of the support members have a mutual distance in the range 1-3 m, such as in the range 1.5-2.5 m.

In some embodiments, the support members are arranged in an array with substantially equal distance from one support member to the next. In some embodiments, this distance is in the range 1-3 m, such as in the range 1.5-2.5 m.

In some embodiments, the step of gradually displacing the support members comprises displacing a first support member arranged closest to the first end of the spar cap part and proceeding to remove a subsequent support member until all support members have been removed from under the spar cap part. In some embodiments, the support members are removed one by one starting with a first support member arranged closest to the first end of the spar cap part and proceeding in sequence along the spar cap part towards the second end of the spar cap part. This allows for a very controlled process, since the spar cap part is passively supported by the support members. This has the advantage that there is no need to continuously steer and lower the spar cap part once the process has been started. Methods in accordance with the present invention are not susceptible to this problem.

In some embodiments, one or more support members are supported by edges of the mould. The edges of the mould usually serve to define leading and trailing edges of a shell part and to support resin infusion and air evacuation equipment during formation of the composite material. However, the edges are perfectly suited for use in embodiments of the present invention, in particular for supporting the support members described above. In some embodiments, the support members are rollers. The support members can for instance be made of cardboard or plastic or metal. In some cases, a slippery surface may be advantageous as it makes the rollers easier to remove.

In some embodiments, the precured reinforcement elements have a stackable shape. For instance, the precured reinforcement elements may have a rectangular cross-section, for instance a uniform cross-section along their entire length.

In some embodiments, one or more of the precured reinforcement elements comprise a chamfered first end and/or a chamfered second end.

In some embodiments, one or more of the precured reinforcement elements are fibre-reinforced composite pultrusions. Pultrusions can replace at least part of laying up fibre in the mould, and pultrusions are relatively easy to manufacture, since most pultrusion processes are mostly automated and produce elements with low variability.

In some embodiments, the spar cap part comprises carbon fibres.

In some embodiments, the spar cap part comprises glass fibres.

Other fibre types, such as steel fibres, may alternatively or additionally be used. Any combination of fibre types may be used.

In some embodiments, one or more of the outer skin fibre layers comprise glass fibres and/or carbon fibres. Other types of fibre may be used.

In some embodiments, one or more of the outer skin fibre layers comprise woven material, such as uniaxial and/or biaxial and/or triaxial material.

In some embodiments, the spar cap part is suspended over the mould by means of at least two suspension devices prior to the step of bringing the spar cap part into contact with one or more of the outer skin fibre layers, and the step of bringing the spar cap part into contact with one or more of the outer skin fibre layers comprises lowering the suspension devices such that the spar cap part is gradually brought into contact with one or more of the outer skin fibre layers, starting from the first end.

In some embodiments, the suspension devices are in turn attached to a lifting beam.

Lowering means allows the suspension devices to be lowered down to the fibre layers gradually and in a controlled manner. The lowering means may for instance be cables attached to a lifting beam and to the suspension devices, or the lifting beam may be height-adjustable. In some embodiments, one or more of the suspension devices comprise a strop surrounding the spar cap part.

In some embodiments, the spar cap part comprises a plurality of reinforcement elements arranged as a plurality of layers, each layer comprising a plurality of the reinforcement elements.

In some embodiments, the provided spar cap part comprises a plurality of precured reinforcement elements that are not bonded together but are strapped together by one or more straps, and during at least a part of the step of gradually bringing the spar cap part into contact with one or more of the outer skin fibre layers, the one or more straps are removed. The straps hold the plurality of precured reinforcement elements in a fixed configuration relative to one another. In other words, the straps prevent displacement of the plurality of precured reinforcement elements relative to one another. By only removing the straps during the step of gradually bringing the spar cap part into contact with one or more of the outer skin fibre layers, the risk that the precured reinforcement elements displace relative to one another is greatly reduced.

In some embodiments, the reinforcement elements are strip-shaped or plank-shaped.

In some embodiments, the spar cap part has a width in the range 10-1000 mm, such as in the range 50-1000 mm, such as in the range 50-500 mm.

In some embodiments, the spar cap part has a height in the range 5-200 mm, such as in the range 5-100 mm. The height may also be considered a thickness, adding to a thickness of the shell part at the position where the spar cap part is placed.

The width and/or thickness may be constant along an entire length of the spar cap part, or the width and/or thickness may vary along the length of the spar cap part.

In some embodiments, one or more of the reinforcement elements have a length in the range 3- 200 m.

A second aspect of the invention provides a wind turbine blade shell part obtainable by a method in accordance with an embodiment of the first aspect of the invention.

Brief description of the drawings

The invention is explained in detail below with reference to the embodiments shown in the drawings.

Fig. 1 is a schematic view illustrating an exemplary wind turbine. Fig. 2 is a schematic view illustrating an exemplary wind turbine blade.

Fig. 3 is a schematic view illustrating a cross-section of an exemplary wind turbine blade.

Fig. 4 is a schematic view illustrating an exemplary wind turbine blade shell part mould.

Fig. 5 is a schematic view illustrating a cross-section of a shell part mould with fibre layers and precured elements.

Figs. 6A-6L illustrate a method in accordance with an embodiment of the invention, for arranging precured elements on fibre layers arranged in a shell part mould.

Figs. 7A-7G illustrate a method in accordance with an embodiment of the invention, for arranging precured elements on fibre layers arranged in a shell part mould.

Detailed description of selected embodiments

Embodiments of the invention will be described in more detail in the following with reference to the accompanying drawings. Like reference numerals may refer to like elements throughout. The drawings show selected ways of implementing the present invention and are not to be construed as being limiting. Unless otherwise indicated, the drawings are not necessarily drawn to scale. The size of the different elements and their shape may have been chosen to make the different elements clearly discernible.

Fig. 1 illustrates a conventional modern upwind wind turbine 2 according to the so-called "Danish concept" with a tower 4, a nacelle 6 and a rotor with a substantially horizontal rotor shaft. The rotor includes a hub 8 and three blades 10 extending radially from the hub 8, each blade having a blade root 16 nearest the hub and a blade tip 14 furthest from the hub 8. The invention is not limited to use in wind turbines of this type.

Fig. 2 shows a schematic view of an exemplary wind turbine blade 10. The wind turbine blade 10 has the shape of a conventional wind turbine blade with a root end 17 and a tip end 15 and comprises a root region 30 closest to the hub, a profiled or airfoil region 34, and a transition region 32 between the root region 30 and the airfoil region 34. The blade 10 comprises a leading edge 18 facing the direction of rotation of the blade 10, when the blade is mounted on the hub, and a trailing edge 20 facing the opposite direction of the leading edge 18.

The airfoil region 34 (also called the profiled region) preferably has an ideal shape with respect to generating hub rotation, whereas the root region 30 due to structural considerations has a substantially circular or elliptical cross-section, which for instance makes it easier and safer to mount the blade 10 to the hub. The diameter of the root region 30 may be constant along the entire root area 30. The transition region 32 present in the wind turbine blade 10 in this example has a transitional profile gradually changing from the circular shape of the root region 30 to the airfoil profile of the airfoil region 34. The chord length of the transition region 32 typically increases in an outward direction from the hub. The airfoil region 34 has an airfoil profile with a chord extending between the leading edge 18 and the trailing edge 20 of the blade 10.

It should be noted that different sections of the blade normally do not have a common plane, since the blade may be twisted and/or curved (i.e. pre-bent) along a direction from the root region to the tip, this being most often the case, for instance to more or less compensate for the local velocity of the blade being dependent on the distance from the hub.

The wind turbine blade 10 comprises a blade shell which may for instance comprise two blade shell parts, a first blade shell part 24 and a second blade shell part 26, for instance made at least partly of fibre-reinforced polymer. The first blade shell part 24 may for instance be part of a pressure side or upwind blade part. The second blade shell part 26 may for instance be part of a suction side or downwind blade part. The first blade shell part 24 and the second blade shell part 26 are typically joined together, such as glued together, along bond lines or glue joints 28 extending along the trailing edge 20 and the leading edge 18 of the blade 10. Typically, the root ends of the blade shell parts 24, 26 have a semi-circular or semi-oval outer cross-sectional shape that, when the first and second shell parts are joined, forms the root region, such as a circular or oval root region.

Fig. 3 is a schematic diagram illustrating a cross-sectional view of the exemplary wind turbine blade 10, corresponding to line A-A in Fig. 2. The wind turbine blade 10 comprises shear webs 40, a first spar cap 74 that is part of the pressure side 24 of the blade 10, and a second spar cap 76 that is part of the suction side 26 of the blade 10. The spar caps provide structural strength to the blade and typically extend along the blade in a spanwise direction. Typically, spar caps will extend over 60-95% of the blade length. The trailing edge 20 and leading edge 18 are also indicated in Fig. 3.

Increasingly, spar caps are made at least partly using prefabricated reinforcing elements, for instance fibre-reinforced composite materials. These can be made separately in a number of ways, such as by a manual, semiautomated or automated process. Another option is to make the reinforcing elements using a pultrusion process. The prefabricated elements replace some of the fibre mats that would otherwise need to be laid up during manufacturing of a wind turbine blade.

Fig. 4 illustrates a mould 80 for manufacturing a blade shell part, such as shell part 24 or 26 illustrated in Figs. 2 and 3. As part of the manufacturing process, layers 81 of dry fibre, including for instance fibre mats, are laid up in the blade shell part mould 80. These will constitute the outer skin of the shell part. After adding the fibre layers 81, one or more precured elements 82, such as a spar cap part, can be added to form a reinforcing part of the blade.

Arranging the spar cap part 82 onto the fibre layers 81 is tedious, and often the fibre layers 81 get displaced or wrinkled during the process of arranging the spar cap part on the fibre layers 81.

Fig. 5 illustrates a cross-section of the mould 80 of Fig. 4 corresponding to line B-B indicated in Fig. 4. Fig. 5 shows in a perspective view how prefabricated elements 82 have been arranged onto the fibre layers 81 in the mould 80. In this example, the spar cap part 82 comprises two stacks of four planks made for instance from glass- and/or carbon-fibre reinforced composite material using a pultrusion process. As current wind turbine blades are easily 70 m long, and blades with a length exceeding 100 m are currently being offered, the planks are correspondingly long, having a length typically in the range 60-95 % of the entire length of the blade. The pultrusions 82 are therefore difficult to handle and arrange. When there are several elements, as in this example, arranging the pultrusions 82 on the fibre layers 81 is even more tedious, as the pultrusions 82 may shift relative to one another. Embodiments of the present invention mitigate this problem.

Fig. 6A shows the cross-section C-C, indicated in Fig. 4, along the spanwise direction of the mould 80 with fibre layers 81, and through the stacks of pultrusions 82. In Fig. 6A, the pultrusions are carried by a lifting beam 101. The pultrusions 82 have been picked up from another location, and the lift has subsequently been arranged over the mould, or the mould under the lifting beam 101, and located in the position where the pultrusions 82 are to be delivered into the mould 80. The pultrusions 82 may for instance be held by strops, indicated by elements 111 and 112, or other suitable suspension devices. The pultrusions may additionally be strapped together. By strapping the elements together, they will not displace relative to one another during the process. Straps are not shown in the drawings but may be arranged anywhere along the pultrusions 82 to hold them together, if needed. Rollers 91, 92, 93 are arranged on the edges of the mould 80 in order to initially support the pultrusions 82 before they are finally lowered onto the fibre layers 81. The rollers can be made of cardboard or plastic or other suitable material. A slippery surface makes the rollers easier to remove during the process.

Fig. 6A also illustrates the first end 82a and the second end 82b of the spar cap part.

Fig. 6B illustrates cross-section D-D indicated in Fig. 6A. The cross-section is the same as that indicated by line B-B in Fig. 3. As described in relation to Fig. 6A, the pultrusions 82 are carried by suspension devices 111, 112 attached to the lifting beam 101. Fig. 6B shows in a perspective view of the pultrusions 82 suspended above the mould 80 and the fibre layers 81. For simplicity, the suspension devices 111, 112 and lifting beam 101 are not included in this figure. Fig. 6B shows the rollers 91, 92, 93 in the same cross-section, C-C (defined in Fig. 4).

Fig. 6C shows the pultrusions having been lowered to be supported by the rollers 91, 92, 93. The rollers allow personnel to remove the suspension devices 111, 112 from the pultrusions 82. As described above, the pultrusions may also be strapped together, and some or all of such straps can be removed easily because the underside of the pultrusions 82 is accessible at this point. As can be seen in Fig. 6C, the pultrusions typically bend somewhat, due to their flexible properties. The degree of bending in the pultrusions 82 is exaggerated in the drawings for illustrative purposes.

Fig. 6D shows the cross-section D-D corresponding to the step shown in Fig. 6C. Since pultrusions for wind turbine blades are quite flexible, there will be a bending as the pultrusions rest on the rollers 91, 92, 93. In the example in Figs. 6C-6D, there is a slight bending in the pultrusions. The present invention takes advantage of this very property.

Because the roller 91 in Fig. 6D is quite close to the first end 82a of the pultrusions 82, the bending is relatively small. Flowever, by removing the rollers or displacing them along the pultrusions 82 towards the second end 82b, the first end 82a will eventually be able to come into contact with the fibre layers 81.

One way to proceed from Fig. 6C-6D is to unfasten the suspension device 111 closest to the first end 82a of the pultrusions 82, as shown in Fig. 6E. Then, as shown in Fig. 6F, the roller 91 closest to the first end 82a is removed. This causes the flexible pultrusions 82 to eventually come into contact with the fibre layers 81, as shown in Fig. 6F.

The number of rollers and the number of suspension device are adjusted to take into account the length of the pultrusions as well as their elastic properties. By using more rollers and suspension devices, the process requires that less lifting be performed, for instance by personnel.

A reason the steps of Fig. 6D and 6E are performed in that order is that the suspension device 111 would otherwise be supporting the pultrusions 82 all the way from the first end 82a to the suspension device 111, making it difficult to remove the suspension device 111 in a controllable manner.

Fig. 6G illustrates the configuration in Fig. 6F as seen in the cross-section D-D (see Fig. 6A). The pultrusions 82 are now partly in contact with the fibre layers 81. During the process, the pultrusions 82 can be displaced as necessary. For instance, if needed, the pultrusions 82 can be shifted sideways towards the leading edge (moving them to the right in the view Fig. 6G) or towards the trailing edge (moving them to the left in the view in Fig. 6G). Spanwise adjustment is also easily performed at this point, as only a small part of the pultrusions are in contact with the fibre layers 81 and therefore can be readily adjusted. This allows for very precise placement of the pultrusions 82 onto the fibre layers 81. Fig. 6G also shows the rollers 91 and 92 still supporting part of the pultrusions 82.

Another advantage of the method is that it is very easy to monitor any undesirable wrinkling in the fibre layers 81, by virtue of the continuous, gradual fashion, in which the pultrusions 82 are being brought into contact with the fibre layers 81. Monitoring is required mostly at the point where the pultrusions 82 are currently being brought into contact with the fibre layers 81. Then, if any wrinkles are observed, measures can be taken to reduce or eliminate the wrinkles, or fibre material can be added (or in some cases removed) to compensate for any deformation that the pultrusions impart on the fibre layers 81.

Next, as shown in Fig. 6H, the next suspension device 112 is unfastened from the pultrusions 82, similarly to the step shown in Fig. 6E for the first suspension device 111. Straps holding the pultrusions together can also be removed before the next portion of the pultrusions 82 is brought into contact with the fibre layers 81.

As the next step, shown in Fig. 61, the next roller 92 is removed. This causes the flexible pultrusions 82 to come into further contact with the fibre layers 81, as seen in Fig. 61.

Fig. 6J illustrates the configuration in Fig. 6F as seen in the cross-section D-D (see Fig. 6A). The pultrusions are now further in contact with the fibre layers 81, while still being supported at the far end by roller 93.

Finally, the last roller 93 is removed from under the pultrusions 82, whereby the process of arranging the pultrusions 82 on the fibre layers 81 is complete, ending with the second end 82b of the pultrusions coming into contact with the fibre layers 81, as shown in Fig. 6K. Fig. 6L shows the configuration as seen in the cross-section D-D.

Depending on the number of rollers and the configuration of the pultrusions, it may be required that a roller be removed by simply pulling it out sideways (e.g. to the left or to the right in the perspective view shown in Fig. 6L), or it may be required that a roller is displaced towards the second end 82b of the pultrusions in a gradual manner. In this case, a slippery roller may be advantageous.

As can be seen from the description above, the method provides that precured elements can be arranging on fibre layers in a mould in a highly controllable manner.

The process can also be performed without supporting members, such as the rollers described above. Figs. 7A-7G illustrate an embodiment of the invention that does not rely on support members. As illustrated in Fig. 7A, the pultrusions 82 are initially suspended using suspension devices 111, 112, 113 held in a lifting beam 101 above the mould 80. No rollers are arranged to support the pultrusions 82 and separate them from the fibre layers 81. Instead, the method relies on a gradual lowering of the suspension devices 111, 112, 113 in such a manner that the first end 82a comes into contact with the fibre layers 81 as the first part of the pultrusions 82. This is illustrated in Fig. 7B. With intervention, typically by personnel, the first suspension device 111 is unfastened from the pultrusions and brought out of the way as illustrated in Fig. 7C.

As shown in Fig. 7D, the pultrusions are then further lowered by lowering suspension devices 112 and 113 until the suspension device 112 is very close to the fibre layer 81. Similar to suspension device 111, suspension device 112 is then unfastened and then brought out of the way, as illustrated in Fig. 7E.

Next, as shown in Fig. 7F, suspension device 113 is lowered until the pultrusions 82 are very close to the fibre layers 81.

Then, the suspension device 113 is removed and brought out of the way, as shown in Fig. 7G. In this last step, the second end 82b comes into contact with the fibre layers as the last part of the pultrusions 82. The process of arranging the pultrusions 82 on the fibre layers is complete.

After the fibre layers 81 and the pultrusions 82 have been provided in the mould 80, any further layers and/or components are added to the layup, including for instance fibre layers forming the inner side of the shell part. To complete the blade shell part, liquid resin is added, and the part is cured.

This process can for instance be a vacuum-assisted resin transfer moulding process, where a flexible vacuum bag is arranged on top of the layup and sealed against the mould 80, whereby a mould cavity is formed, containing the layup. Resin inlets and vacuum outlets are connected to the cavity in preparation for a process known as infusion. The inlets allow resin to be introduced into the mould cavity, and the outlets allow air to be removed. The cavity is evacuated via the vacuum outlets, forming an underpressure in the mould cavity. Then, a supply of liquid resin is provided via the resin inlets. The resin is forced into the mould cavity at least due to the pressure differential created by the evacuation. The resin disperses in different directions in the mould cavity due to the negative pressure, which drives the resin flow front(s) towards the vacuum outlets. In the mould cavity, the resin impregnates the layup. When the layup has been fully impregnated, the resin is cured, resulting in the fibre-reinforced composite wind turbine shell part. List of references

2 wind turbine

4 tower

6 nacelle

8 hub

10 blade

14 blade tip

15 tip end

16 blade root

17 root end

18 leading edge

20 trailing edge

24 first blade shell part (pressure side)

26 second blade shell part (suction side)

28 bond lines/glue joints

30 root region

32 transition region

34 airfoil region

34a first airfoil region

34b second airfoil region

40 shear web or spar sides of a spar box

44 first blade section

45 interface between first and second blade sections

46 second blade section

74 first spar cap

76 second spar cap

80 wind turbine blade shell part mould

81 fibre layers

82 pultrusion(s), spar cap part, precured element(s)

82a first end of precured component

82b second end of precured component

91-93 rollers, support members

101 lifting beam

111-113 suspension devices

Claims

1. A method for manufacturing a wind turbine blade shell part (26) having a tip end (14) and a root end (16), comprising: laying up one or more outer skin fibre layers (81) in a wind turbine blade shell part mould (80), providing a spar cap part (82) comprising one or more precured elongate reinforcement elements, the spar cap part having a first end (82a) and a second end (82b), gradually bringing the spar cap part into contact with one or more of the outer skin fibre layers (81), starting from the first end (82a), laying up one or more inner skin fibre layers in contact with the spar cap part (82), providing liquid resin into the mould and curing the resin, thereby obtaining the wind turbine blade shell part.

2. A method in accordance with claim 1, wherein bringing the spar cap part (82) into contact with one or more of the outer skin fibre layers (81) ends with bringing the second end (82b) of the spar cap part (82) into contact with one or more of the outer skin fibre layers.

3. A method in accordance with any of the preceding claims, wherein bringing the spar cap part into contact with one or more of the outer skin fibre layers is initiated at a first position in the mould (80) and ends at a second position in the mould (80), wherein the first position is closer to the tip end (14) of the blade than the second position is.

4. A method in accordance with any of the preceding claims, wherein the step of gradually bringing the spar cap part (82) into contact with one or more of the outer skin fibre layers (81) comprises: placing the spar cap part (82) on one or more support members (91, 92, 93) arranged above the outer skin fibre layers at respective support member positions, each support member (91, 92, 93) supporting the spar cap part and separating the spar cap part from the outer skin fibre layers (81), displacing the support members (91, 92, 93) so as to gradually bring the spar cap part into contact with the outer skin fibre layers, and removing the support members from under the spar cap part.

5. A method in accordance with claim 4, wherein the step of gradually displacing the support members (91, 92, 93) comprises displacing a first support member arranged closest to the first end of the spar cap part and proceeding to remove a subsequent support member until all support members have been removed from under the spar cap part (82).

6. A method in accordance with claim 4 or 5, wherein the support members are removed one by one starting with a first support member arranged closest to the first end (82a) of the spar cap part and proceeding in sequence along the spar cap part towards the second end (82b) of the spar cap part (82).

7. A method in accordance with any of claims 4-6, wherein one or more support members are supported by edges of the mould.

8. A method in accordance with any of claims 4-7, wherein the support members are rollers.

9. A method in accordance with any of the preceding claims, wherein one or more of the precured elongate reinforcement elements have a rectangular cross-section.

10. A method in accordance with any of the preceding claims, wherein one or more of the precured elongate reinforcement elements comprise a chamfered first end (82a) and/or a chamfered second end (82b).

11. A method in accordance with any of the preceding claims, wherein one or more of the precured reinforcement elements are fibre-reinforced composite pultrusions.

12. A method in accordance with any of the preceding claims, wherein the spar cap part comprises carbon fibres.

13. A method in accordance with any of the preceding claims, wherein the spar cap part comprises glass fibres.

14. A method in accordance with any of the preceding claims, wherein one or more of the outer skin fibre layers (81) comprise glass fibres and/or carbon fibres.

15. A method in accordance with any of the preceding claims, wherein one or more of the outer skin fibre layers comprise woven material, such as uniaxial and/or biaxial and/or triaxial material.

16. A method in accordance with any of the preceding claims, wherein the spar cap part (82) is suspended over the mould (80) by means of at least two suspension devices (111, 112, 113) prior to the step of bringing the spar cap part into contact with one or more of the outer skin fibre layers (81), and the step of bringing the spar cap part into contact with one or more of the outer skin fibre layers comprises lowering the suspension devices such that the spar cap part is gradually brought into contact with one or more of the outer skin fibre layers, starting from the first end (82a).

17. A method in accordance with claim 15 or 16, wherein one or more of the suspension devices

(111, 112, 113) comprise a strop surrounding the spar cap part.

18. A method in accordance with any of the preceding claims, wherein the spar cap part comprises a plurality of reinforcement elements arranged as a plurality of layers, each layer comprising a plurality of the reinforcement elements.

19. A method in accordance with any of the preceding claims, wherein the provided spar cap part comprises a plurality of reinforcement elements that are not bonded together but are strapped together by one or more straps, and wherein during at least a part of the step of gradually bringing the spar cap part into contact with one or more of the outer skin fibre layers, the one or more straps are removed.

20. A method in accordance with any of the preceding claims, wherein the reinforcement elements are strip-shaped or plank-shaped.

21. A method in accordance with any of the preceding claims, wherein the spar cap has a width in the range 50-1000 mm.

22. A method in accordance with any of the preceding claims, wherein the spar cap has a height in the range 5-100 mm.

23. A method in accordance with any of the preceding claims, wherein one or more of the reinforcement elements have a length in the range 3-200 m.

24. A wind turbine blade shell part obtainable by a method in accordance with any of claims 1-

23.