Segmented Wind Turbine Blade Manufacturing

Abstract

The present invention relates to a method of manufacturing a wind turbine blade, the method including the steps of manufacturing pressure and suction side shell halves and placing a spar structure (62) within one of the shell halves. The spar structure (62) comprises two portions releasably coupled to one another. The method results in a segmented wind turbine blade for easy transportation and reassembly.

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a wind turbine blade, and to a wind turbine blade obtained by said method. [Background technology]

[0002] Wind power provides a clean, environmentally friendly source of energy. A wind turbine typically comprises a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The wind turbine blades extract the kinetic energy of the wind using the well-known airfoil principle. Modern wind turbines can have rotor blades over 90 metres in length.

[0003] Wind turbine blades are typically manufactured by forming two shell sections or halves from layers of woven fabric or fiber and resin. A spar cap or primary laminate is placed on or integrated with the shell halves and may be combined with a shear web or spar beam to form a structural support member. The spar cap or primary laminate may be bonded to or integrated on the inside of the suction side and pressure side halves of the shell.

[0004] As wind turbines increase in size, manufacturing and transporting wind turbine blades becomes more difficult and expensive. To address this, it is known to provide wind turbine blades in two or more segments. This may result in an easier manufacturing process and may reduce the cost of transporting and installing the wind turbine. The blade segments can be transported to an installation site where they can be assembled to form the wind turbine blade.

[0005] However, several challenges may be associated with such designs regarding the manufacturing and joining of shell segments that contain load-bearing structures such as spar beams, shear webs, or other interior components.

[0006] It is therefore an object of the present invention to provide a wind turbine blade that has improved stability and is easier to manufacture, handle and assemble.

[0007] Another object of the present invention is to provide an efficient method for manufacturing a segmented wind turbine blade having an internal stiffening structure. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] US Patent Application Publication No. 2018 / 223796 Summary of the Invention

[0009] The invention relates to a method for manufacturing a wind turbine blade having a profile contour including a pressure side and a suction side, a leading edge and a trailing edge, the chord having a chord length extending between the leading edge and the trailing edge, the wind turbine blade extending in a spanwise direction between a root end and a tip end, the method comprising the steps of manufacturing a pressure side shell half and a suction side shell half over substantially the entire length of the wind turbine blade, closing and joining the shell halves to obtain a closed shell, cutting the closed shell along cutting planes substantially perpendicular to the spanwise direction of the closed shell to obtain first and second blade segments, each blade segment comprising a portion of the pressure side shell half and a portion of the suction side shell half, separating the first blade segment from the second blade segment, and joining and sealing the first blade segment to the second blade segment to obtain a wind turbine blade.

[0010] The method provides an improved and efficient approach to segmenting and reassembling wind turbine blades.Preferably, the method further includes positioning a spar structure within one of the shell halves prior to closing and joining the shell halves.

[0011] It has also been found that one or more of the above-mentioned objects may be obtained by a method of manufacturing a wind turbine blade having a profile contour including a pressure side and a suction side, a leading edge and a trailing edge, the chord having a chord length extending between the leading edge and the trailing edge, the wind turbine blade extending spanwise between a root end and a tip end, the method comprising: a1) manufacturing a pressure side half shell and a suction side half shell over substantially the entire length of a wind turbine blade; b1) placing a spar structure within one of the shell halves, the spar structure comprising a first portion and a second portion, the first and second portions being releasably coupled to one another; c1) closing and joining the shell halves to obtain a closed shell; d1) cutting the closed shell along cut planes substantially perpendicular to a spanwise direction of the closed shell to obtain first and second blade segments, each blade segment comprising a portion of a pressure side shell half and a portion of a suction side shell half, the spar structure extending across the cut planes; e1) decoupling the first and second portions of the spar structure; f1) separating the first blade segment from the second blade segment; g1) joining and sealing the first blade segment to a second blade segment to obtain a wind turbine blade; Includes.

[0012] By manufacturing a wind turbine blade using a spar structure comprising a first portion and a second portion releasably connected to one another, an efficient and elegant method for segmenting and reassembling such a wind turbine blade, including decoupling, and preferably recoupling, the portions, is provided.

[0013] Preferably, the pressure side and suction side shell halves are manufactured over the entire length of the wind turbine blade, i.e., over their final length. The pressure side and suction side shell halves are typically glued or bonded to each other near the leading edge and the trailing edge. Each shell half may comprise a longitudinal / spanwise extending load-bearing structure, such as one or more primary laminates or spar caps, preferably including reinforcing fibers, such as glass fiber, carbon fiber, aramid fiber, metal fiber, e.g. steel fiber, or plant fiber, or a mixture thereof. The shell halves are typically manufactured by injecting a resin, such as epoxy, polyester, or vinyl ester, into a fiber layup of fibrous material.

[0014] Typically, the pressure side and suction side shell halves are manufactured using a mold structure. In some embodiments, the shell halves remain in the mold structure during steps a1, b1, and c1. Each of the shell halves may include a spar cap or primary lamination disposed along the respective pressure and suction side shell members. The spar cap or primary lamination may be attached to an inner surface of the shell half.

[0015] The spar structure is preferably a longitudinally extending load-bearing structure, preferably comprising beams or spar boxes for connecting and stabilizing the shell halves, and may be adapted to carry a substantial portion of the load on the blades.

[0016] In some embodiments, the spar structure is disposed in the pressure side shell half in step b1). In other embodiments, the spar structure is disposed in the suction side shell half in step b1). The spar structure comprises a first portion and a second portion, the first and second portions being releasably coupled to one another, such as being releasably fixed or locked to one another. In some embodiments, the first and second portions are releasably coupled to one another by one or more mechanical devices. In some embodiments, the first and second portions are releasably coupled to one another by a mechanical locking mechanism. The second portion of the spar structure may advantageously comprise a spar beam or a spar box. The first portion of the spar structure may preferably comprise a configuration for receiving the second portion, such as a hollow member or a sheath.

[0017] The joining step in c1) can be performed using any suitable joining mechanism or process, including adhesives, bonding materials, mechanical fasteners, and any combination thereof. The closed shell obtained in c1) is preferably a full length preform of the final wind turbine blade obtained by the method of the present invention.

[0018] In step d1) the closed shell is cut along a cutting plane that is substantially perpendicular to the spanwise or longitudinal axis of the closed shell. In other words, the spanwise or longitudinal axis of the closed shell is substantially perpendicular to said cutting plane. Preferably, only the shell body is cut along the cutting plane. Also, preferably, the spar structure is not cut in step d1.

[0019] In some embodiments, the first blade segment comprises 30-80%, such as 40-70%, of the total longitudinal extent of the blade. In some embodiments, the second blade segment comprises 10-50%, such as 20-40%, of the total longitudinal extent of the blade. Advantageously, the spar structure preferably extends uncut across the cut surface. The first and second blade segments may include respective ends having complementary junction sections joinable at a chordwise junction.

[0020] Step e1) of decoupling the first and second portions of the spar structure is preferably performed by unlocking a mechanical locking mechanism. In some embodiments, decoupling is performed through an opening formed in one or both of the shell halves, preferably an opening in the first blade segment. Such an opening may be formed after the cutting operation of step d1) or prior to the cutting operation.

[0021] After separating the first blade segment from the second blade segment in step f1), the individual blade segments can be transported individually, for example by respective trucks. The first blade segment and the second blade segment can be transported to an installation site for the wind turbine.

[0022] The step g1) of joining and sealing the first blade segment to the second blade segment to obtain the wind turbine blade can advantageously be performed at the installation site of the wind turbine. This step can be performed using any suitable joining and / or sealing mechanism or process, including adhesives, bonding materials, mechanical fasteners, and any combination thereof.

[0023] In preferred embodiments, the first portion of the spar structure is fixed to the first blade segment. In some embodiments, the first portion of the spar structure is bonded or adhered to the first blade segment, preferably to both the partial suction side shell half and the partial pressure side shell half. In preferred embodiments, the first portion of the spar structure does not extend beyond the first blade segment.

[0024] According to some embodiments, the second portion of the spar structure is secured, such as by gluing or bonding, to the second blade segment, preferably to both partial shell halves. The second portion of the spar structure preferably extends beyond the second blade segment into the first blade segment. Thus, the second portion of the spar structure preferably protrudes from within the second portion of the spar structure.

[0025] In a preferred embodiment, the first blade segment comprises the root end of the blade. In another preferred embodiment, the second blade segment comprises the tip end of the blade. The blade may also be cut into three or more segments.

[0026] In some embodiments, the second portion of the spar structure comprises a spar member, such as a spar beam or a spar box, the spar box preferably comprising at least one spar beam and at least one spar flange. In some embodiments, the first portion of the spar structure comprises a receiving member, preferably a sheath member, for at least partially receiving or surrounding the second portion of the spar structure. In some embodiments, the second portion of the spar structure comprises a spar member that is at least partially received or surrounded by the receiving structure. The receiving structure can be a jacket, for example a jacket comprising a mesh or net-like structure. In some embodiments, the jacket is made of the same material as the sheath member of the first portion of the spar structure. The jacket is preferably a conductive jacket.

[0027] According to some embodiments, the sheath member is substantially box-shaped. In other embodiments, the sheath member is hollow. In other embodiments, the sheath member comprises a mesh or net structure. In a preferred embodiment, the sheath member is a conductive sheath member.

[0028] In a preferred embodiment, the electrically conductive sheath member is part of a lightning protection system for the wind turbine blade. In a preferred embodiment, the electrically conductive sheath member of the first portion and the electrically conductive jacket of the second portion are both part of a lightning protection system for the wind turbine blade.

[0029] According to some embodiments, step b1) includes fastening the first portion of the spar structure to one or both shell halves in the first blade segment obtained in step d1). Thus, step b1) may include fastening the first portion of the spar structure to a partial suction side shell half and a partial pressure side shell half of a subsequently obtained first blade segment, such as a root end blade segment.

[0030] In a preferred embodiment, step b1) includes fastening the second portion of the spar structure to one or both shell halves in the second blade segment obtained in step d1). Thus, step b1) may include fastening the second portion of the spar structure to a partial suction side shell half and a partial pressure side shell half of a subsequently obtained second blade segment, such as a tip end blade segment.

[0031] In a preferred embodiment, the spar structure comprises at least one locking pin for releasably coupling a first portion of the spar structure to a second portion through aligned respective locking openings in each of the first and second portions of the spar structure. In other embodiments, the spar structure comprises two or more, e.g., three or more, or four or more locking pins and two or more, e.g., three or more, or four or more respective locking openings in each of the first and second portions of the spar structure. Preferably, the locking openings are respective through holes formed in the sheath member and the spar member, respectively.

[0032] According to some embodiments, step e1) comprises cutting an access opening through at least one of the shell halves to access the spar structure. Preferably, the access opening is cut through the shell material to allow access to the inside of the blade, in particular to the spar structure, in particular to its locking pin or pins. The access opening may be an access panel, such as a substantially rectangular access panel cut through the shell material to access the inside of the blade. The access opening is preferably a closable opening. Typically, the access opening is closed and / or sealed by a cover before completing the wind turbine blade.

[0033] In a preferred embodiment, step e1) includes withdrawing a locking pin from an aligned respective opening in each of the first and second portions of the spar structure, preferably through the access opening.

[0034] In a preferred embodiment, the method further comprises the step f2) or h1) of reconnecting the first and second portions of the spar structure. Thus, once the blade segments have been rejoined, the first and second portions may advantageously be reconnected to secure and lock the first portion to the second portion.

[0035] According to some embodiments, steps f2) and h1) include reinserting the locking pins into aligned respective openings in each of the first and second portions of the spar structure, preferably through the access openings.

[0036] In a preferred embodiment, step d1) does not include cutting the spar structure.

[0037] According to some embodiments, the cutting surface of step d1) is located within a spanwise region of 0.5L to 0.8L from the root end, L being the total length or longitudinal extent of the wind turbine blade between its root end and its tip end.

[0038] In a preferred embodiment, the cut surface of step d1) coincides with the end surface of the first portion of the spar structure.

[0039] The cut surface of step d1) preferably extends across the second portion of the spar structure.

[0040] According to some embodiments, step g1) is performed using a seal member positioned between the first and second blade segments, the seal member configured to allow relative movement between the first and second blade segments.

[0041] In a preferred embodiment, the pressure side shell half and the suction side shell half are manufactured in respective mold halves, preferably by vacuum assisted resin transfer molding.

[0042] According to some embodiments, the pressure side half shell and the suction side half shell each have a longitudinal extent L of 50 to 90 m, preferably 60 to 80 m.

[0043] In a preferred embodiment, the pressure side shell half and the suction side shell half each comprise one or more layers of carbon fiber disposed within the first blade segment obtained in step d1).

[0044] According to some embodiments, the method further comprises a step b2) of disposing one or more shear webs in at least one of the shell halves, preferably the first blade segment obtained in step d1). Each shear web may comprise a web body, a first web leg flange at a first end of the web body, and a second web leg flange at a second end of the web body. In some embodiments, the shear web is substantially I-shaped. Alternatively, the shear web may be substantially C-shaped.

[0045] In a preferred embodiment, step f1) comprises transporting the separated first and second blade segments to a predetermined location. Typically, the predetermined location is a site for installing the wind turbine. Advantageously, the first blade segment can be transported independently of the second blade segment.

[0046] According to some embodiments, step g1) comprises joining and sealing the first blade segment to the second blade segment at said predetermined location.

[0047] In another aspect, the invention relates to a wind turbine blade obtained by the method according to the invention, which can be easily and efficiently assembled due to its spar structure and its coupling and decoupling properties.

[0048] In another aspect, the invention relates to a spar structure for a wind turbine blade, the spar structure comprising a first portion and a second portion, the first and second portions being releasably coupled to one another, the second portion of the spar structure comprising a spar member such as a spar beam or a spar box, the spar box comprising at least one spar beam and at least one spar flange, and the first portion of the spar structure comprising a sheath member for at least partially surrounding the second portion of the spar structure. The spar structure may be advantageously used in the methods of manufacturing a wind turbine blade as described herein.

[0049] In a preferred embodiment, the sheathing member is an electrically conductive sheathing member for a lightning protection system for a wind turbine blade.

[0050] According to another preferred embodiment, the spar structure includes at least one locking pin for releasably coupling the first portion of the spar structure to the second portion through aligned respective locking openings in each of the first and second portions of the spar structure.

[0051] As used herein, the term "spanwise" is used to describe the orientation of a measurement or element along a blade from its root end to its tip end. In some embodiments, the spanwise direction is along the longitudinal axis and longitudinal extent of a wind turbine blade.

[0052] The invention is explained in more detail below with reference to embodiments shown in the drawings. [Brief description of the drawings]

[0053] [Figure 1] FIG. 1 shows a wind turbine. [Diagram 2] FIG. 1 is a schematic diagram of a wind turbine blade. [Diagram 3] 1 is a schematic diagram of a cross section of a wind turbine blade; [Figure 4] 1 is a schematic cutaway view of a wind turbine blade according to the present invention; [Diagram 5] FIG. 5 is an enlarged view of the circled section of FIG. 4. [Figure 6] FIG. 1 is a perspective view of a spar structure according to the present invention. [Figure 7] FIG. 1 is a perspective view of a spar structure according to the present invention. [Figure 8] FIG. 1 is a perspective view of a spar structure according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] 1 shows a conventional modern upwind wind turbine according to the so-called "Danish concept" with a tower 4, a nacelle 6, and a rotor having a substantially horizontal rotor shaft. The rotor includes a hub 8 and three blades 10 extending radially from the hub 8, each having a blade root 16 closest to the hub and a blade tip 14 furthest from the hub 8. The rotor has a radius indicated as R.

[0055] 2 shows a schematic diagram of a wind turbine blade 10. Wind turbine blade 10 has a conventional wind turbine blade shape with a root region 30 closest to the hub, a profile or airfoil region 34 furthest from the hub, and a transition region 32 between the root region 30 and the airfoil region 34. Blade 10 has a leading edge 18 that faces in the direction of rotation of blade 10 when the blade is mounted to the hub, and a trailing edge 20 that faces in the opposite direction to leading edge 18.

[0056] The airfoil region 34 (also called the profile region) has an ideal or near-ideal blade shape for lift production, while the root region 30 due to construction considerations has a substantially circular or elliptical cross section, which makes it easier and safer to mount the blade 10 to the hub, for example. The diameter (or chord) of the root region 30 may be constant along the entire root area 30. The transition region 32 has a transition profile that gradually changes from the circular or elliptical 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 as the distance r from the hub increases. The airfoil region 34 has an airfoil profile with a chord that extends between the leading edge 18 and the trailing edge 20 of the blade 10. The width of the chord decreases as the distance r from the hub increases.

[0057] The shoulder 40 of the blade 10 is defined as the location where the blade 10 has its maximum chord length. The shoulder 40 is typically located at the boundary between the transition region 32 and the airfoil region 34. Figure 2 also shows the longitudinal extent L, length, or longitudinal axis of the blade.

[0058] It should be noted that the chords of different sections of the blade typically do not lie in a common plane, since the blade may be twisted and / or curved (i.e. pre-bent) and thus provide a correspondingly twisted and / or curved course in the chord plane, this is mostly to compensate for the local speed of the blade which depends on the radius from the hub.

[0059] The blade is typically made from a pressure side shell portion 36 and a suction side shell portion 38 bonded together along bondlines at the leading edge 18 and trailing edge 20 of the blade.

[0060] FIG. 3 shows a schematic diagram of a cross section of the blade along line II shown in FIG. 2. As mentioned above, the blade 10 comprises a pressure side shell portion 36 and a suction side shell portion 38. The pressure side shell portion 36 comprises a spar cap 41, also called a main laminate, which constitutes the load-bearing portion of the pressure side shell portion 36. The spar cap 41 comprises a plurality of fiber layers 42, mainly including unidirectional fibers aligned along the length of the blade, to provide rigidity to the blade. The suction side shell portion 38 also comprises a spar cap 45, which comprises a plurality of fiber layers 46. The pressure side shell portion 36 may also comprise a sandwich core material 43, typically made of balsa wood or foamed polymer, sandwiched between several fiber-reinforced skin layers. The sandwich core material 43 is used to provide rigidity to the shell, which allows the shell to substantially maintain its aerodynamic profile during rotation of the blade. Similarly, the suction side shell portion 38 may also comprise a sandwich core material 47.

[0061] The spar cap 41 of the pressure side shell portion 36 and the spar cap 45 of the suction side shell portion 38 are connected via a first shear web 50 and a second shear web 55. The shear webs 50, 55 are shaped as substantially I-shaped webs in the illustrated embodiment. The first shear web 50 comprises a shear web body and two web foot flanges. The shear web body comprises a sandwich core material 51, such as balsa wood or foamed polymer, covered by a number of skin layers 52 made of a number of fiber layers.

[0062] The blade shells 36, 38 may include additional fiber reinforcement at the leading and trailing edges. Typically, the shell portions 36, 38 are bonded together via adhesive flanges.

[0063] FIG. 4 is a schematic cutaway exploded view of a wind turbine blade according to the invention, and FIG. 5 is an enlarged view of the circled section of FIG. 4. According to the method of the invention, a pressure side shell half and a suction side shell half are manufactured over the entire length L of the wind turbine blade 10. A spar structure 62 is placed within the shell. The spar structure 62 comprises a first portion 64 and a second portion 66, as shown in FIG. 8, the first and second portions being releasably connected to each other. The method advantageously includes the steps of fixing the first portion 64 of the spar structure 62 to one or both of the shell halves in the first blade segment 68 and fixing the second portion 66 of the spar structure to one or both of the shell halves in the second blade segment 70.

[0064] The shell halves are then closed and joined, such as by being glued together, to obtain a closed shell, and then cut along a cutting plane 69 substantially perpendicular to the spanwise or longitudinal extent of the blade to obtain a first blade segment 68 and a second blade segment 70. Cutting plane 69 coincides with an end face 65 of the first portion 64 of the spar structure.

[0065] As seen in Figures 4 and 5, the spar structure 62 extends across the cutting plane 69. As best seen in Figure 5, a first portion 64 of the spar structure 62, which takes the form of a box-shaped sheathing member for at least partially surrounding a second portion 66 of the spar structure, is secured to a first blade segment 68 in the illustrated embodiment. The second portion 66 of the spar structure 62, which in the illustrated embodiment comprises a spar box, is secured to a second blade segment 70, with the second portion 66 extending beyond the second blade segment 70 and into the first blade segment 68 when the blade segments are assembled.

[0066] FIG. 5 also shows an access opening 80 cut through the top half of the illustrated shell for accessing the spar structure and for coupling and decoupling the first and second parts of the spar structure 62. For decoupling, a locking pin is withdrawn through the access opening 80 from the aligned respective openings 76, 78 in each of the first and second parts of the spar structure, as shown in FIGS. 6-8. Before or after joining and sealing the first blade segment 68 to the second blade segment 70 to obtain the wind turbine blade, the method advantageously includes a step of recoupling the first and second parts of the spar structure by reinserting the locking pin 74 through the access opening 80 into the aligned respective openings 76, 78 in each of the first and second parts of the spar structure, as shown in FIG. 8. As can be seen in FIGS. 4 and 5, the cutting step d1) does not include a step of cutting the spar structure, only the shell halves are cut. In addition, two shear webs 82a, 82b are arranged in the first blade segment.

[0067] 6-8 show an embodiment of a spar structure 62 having a first portion 64 in the form of an electrically conductive box-shaped sheath member. Preferably, the electrically conductive sheath member is part of a lightning protection system for a wind turbine blade. A second portion 66 of the spar structure comprises a box spar 67, a portion of which is housed in a jacket 72, e.g., comprising an electrically conductive mesh 72. The spar structure 62 comprises a locking pin 74 for releasably coupling the first portion 64 to the second portion 66 of the spar structure through aligned respective locking openings 76, 78 in each of the first and second portions of the spar structure.

[0068] The invention is not limited to the embodiments described herein, which may be modified or adapted without departing from the scope of the invention. [Explanation of symbols]

[0069] 4. Tower 6. Nacelle 8. Hub 10 Blades 14 Blade Tip 16 Blade base 18 Leading Edge 20 Trailing edge 30 Root Region 32 Transition Zone 34 Airfoil area 36 Pressure side shell part 38 Negative pressure side shell part 40 Shoulder 41 Super Cap 42 Fiber layer 43 Sandwich Core Materials 45 Super Cap 46 Fiber layer 47 Sandwich Core Materials 50 First shear web 51 Core material 52 Skin Layer 55 Second Shear Web 56 Second shear web sandwich core material 57 Skin layer of second shear web 60 Filler Rope 62 Spar Structure 64 First Part 65 End face of first portion 66 Second Part 67 Spar parts 68 First Blade Segment 69 Cut surface 70 Second Blade Segment 72 Jacket / Mesh 74 Lock pin 76 Aperture 78 Aperture 80 Access opening 82 Shear Web L Length r Distance from hub R Rotor radius

Claims

1. 1. A method of manufacturing a wind turbine blade having a profile contour including a pressure side and a suction side, a leading edge and a trailing edge, the chord having a chord length extending between the leading edge and the trailing edge, the wind turbine blade extending spanwise between a root end and a tip end, the method comprising the steps of manufacturing a pressure side shell half and a suction side shell half over substantially an entire length of the wind turbine blade, and disposing a spar structure (62) within one of the pressure side shell half and the suction side shell half, the spar structure (62) comprising a first portion (64) and a second portion (66) comprising a conductive jacket, the first portion (64) of the spar structure (62) comprising a box-shaped conductive sheathing member for at least partially surrounding the second portion (66) of the spar structure (62), the second portion (66) comprising a conductive jacket. the conductive jacket and the conductive sheath member are part of a lightning protection system for a wind turbine blade, the method comprising: closing and joining the pressure side shell half and the suction side shell half to obtain a closed shell; cutting the closed shell along a cutting plane (69) substantially perpendicular to the span direction of the closed shell to obtain a first blade segment (68) and a second blade segment (70), each blade segment comprising a portion of the pressure side shell half and a portion of the suction side shell half; separating the first blade segment (68) from the second blade segment (70); and joining the first blade segment (68) to the second blade segment (70) to obtain the wind turbine blade.

2. 2. The method of claim 1, further comprising the step of disposing a spar structure (62) within one of the pressure side shell half and the suction side shell half prior to closing and joining the pressure side shell half and the suction side shell half.

3. The method comprises: a1) manufacturing a pressure side half shell and a suction side half shell over substantially the entire length of the wind turbine blade; b1) disposing a spar structure (62) within one of the pressure side shell half and the suction side shell half; c1) closing and joining the pressure side shell half and the suction side shell half to obtain a closed shell; d1) cutting the closed shell along a cutting plane (69) substantially perpendicular to the spanwise direction of the closed shell to obtain a first blade segment (68) and a second blade segment (70), each blade segment comprising a portion of the pressure side shell half and a portion of the suction side shell half, the spar structure (62) extending across the cutting plane (69); e1) decoupling the first portion (64) and the second portion (66) of the spar structure (62); f1) separating said first blade segment (68) from said second blade segment (70); g1) joining said first blade segment (68) to said second blade segment (70) to obtain said wind turbine blade; The method of claim 1 or 2, comprising:

4. The method of claim 3, wherein the first portion (64) of the spar structure (62) is secured to the first blade segment (68).

5. 5. The method of claim 3 or 4, wherein the second portion (66) of the spar structure (62) is secured to the second blade segment (70), and the second portion (66) of the spar structure (62) extends beyond the second blade segment (70) into the first blade segment (68).

6. 1. A method of manufacturing a wind turbine blade having a profile contour including a pressure side and a suction side, a leading edge and a trailing edge, the chord having a chord length extending between the leading edge and the trailing edge, the wind turbine blade extending spanwise between a root end and a tip end, the method comprising the steps of manufacturing a pressure side shell half and a suction side shell half over substantially an entire length of the wind turbine blade, and disposing a spar structure (62) within one of the pressure side shell half and the suction side shell half, the spar structure (62) comprising a first portion (64) and a second portion (66), the first portion (64) of the spar structure (62) comprising a box-shaped sheath member for at least partially surrounding the second portion (66) of the spar structure (62), the sheath member comprising: the conductive sheath member being part of a lightning protection system for a wind turbine blade; closing and joining the pressure side shell half and the suction side shell half to obtain a closed shell; cutting the closed shell along a cutting plane (69) substantially perpendicular to the span direction of the closed shell to obtain a first blade segment (68) and a second blade segment (70), each blade segment comprising a portion of the pressure side shell half and a portion of the suction side shell half; separating the first blade segment (68) from the second blade segment (70); and joining the first blade segment (68) to the second blade segment (70) to obtain the wind turbine blade, The method comprises: a1) manufacturing a pressure side half shell and a suction side half shell over substantially the entire length of the wind turbine blade; b1) disposing a spar structure (62) within one of the pressure side shell half and the suction side shell half; c1) closing and joining the pressure side shell half and the suction side shell half to obtain a closed shell; d1) cutting the closed shell along a cutting plane (69) substantially perpendicular to the spanwise direction of the closed shell to obtain a first blade segment (68) and a second blade segment (70), each blade segment comprising a portion of the pressure side shell half and a portion of the suction side shell half, the spar structure (62) extending across the cutting plane (69); e1) decoupling the first portion (64) and the second portion (66) of the spar structure (62); f1) separating said first blade segment (68) from said second blade segment (70); g1) joining said first blade segment (68) to said second blade segment (70) to obtain said wind turbine blade; Including, The method of claim 1, wherein the second portion (66) comprises at least one spar beam and at least one spar flange.

7. The method of claim 3 , wherein the conductive sheathing member comprises a conductive jacket.

8. The method of claim 7 , wherein the conductive sheathing member comprises a mesh or net-like structure.

9. A method according to any one of claims 3 to 8, comprising a step of fixing the first portion (64) of the spar structure (62) to one or both of the pressure side shell half and the suction side shell half in the first blade segment (68) obtained in step d1).

10. A method according to any one of claims 3 to 9, comprising a step of fixing the second portion (66) of the spar structure (62) to one or both of the pressure side shell half and the suction side shell half in the second blade segment (70) obtained in step d1).

11. 11. The method of any one of claims 3 to 10, wherein the spar structure (62) comprises at least one locking pin (74) for releasably coupling the first portion (64) of the spar structure (62) to the second portion (66) through aligned respective locking openings in each of the first portion (64) and the second portion (66) of the spar structure (62).

12. 12. The method of claim 11, wherein step e1) comprises cutting an access opening (80) through at least one of the pressure side shell half and the suction side shell half to access the spar structure (62).

13. 13. The method of claim 12, wherein step e1) comprises withdrawing the locking pin (74) from the aligned respective locking openings in each of the first and second portions (64, 66) of the spar structure (62) through the access opening (80).

14. 14. The method of claim 3, further comprising the step of reconnecting the first portion (64) and the second portion (66) of the spar structure (62) between steps f1) and g1) or after step g1).

15. 15. The method according to any one of claims 3 to 14, wherein the cut surface (69) of step d1) coincides with an end face of the first portion (64) of the spar structure (62).

16. 16. The method of any one of claims 3 to 15, wherein step f1) comprises transporting the separated first and second blade segments (68) to a predetermined location.

17. A wind turbine blade obtainable by the method according to any one of the preceding claims.

18. A spar structure (62) for a wind turbine blade, the spar structure (62) comprising a first portion (64) and a second portion (66) comprising a conductive jacket, the first portion (64) and the second portion (66) being releasably coupled to one another, the second portion (66) of the spar structure (62) comprising a spar member (67), the first portion (64) of the spar structure (62) comprising a box-shaped conductive sheathing member for at least partially surrounding the second portion (66) of the spar structure (62); The conductive sheath member and the conductive jacket are for a lightning protection system for a wind turbine blade, the spar structure (62) comprising at least one locking pin (74) for releasably coupling the first portion (64) of the spar structure (62) to the second portion (66) through aligned respective locking openings in each of the first portion (64) and the second portion (66) of the spar structure (62).

19. 20. A spar structure (62) as claimed in claim 18; a first blade segment (68) having a first shell portion; a second blade segment (70) having a second shell portion; Including, the first portion (64) is secured to the first blade segment (68); the second portion (66) is secured to the second blade segment (70); The at least one locking pin (74) extends in a rotational direction of the wind turbine blade; the first shell portion includes an access opening (80) on at least one of a pressure side and a suction side of the wind turbine blade for accessing the spar structure (62); A wind turbine blade, wherein the access opening (80) is positioned offset from the spar structure (62) in the direction of rotation.

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