Lifting system for weighing a wind turbine blade

Abstract

A root end lifting beam (50) for securing a root end (17) of a wind turbine blade (10) during a weighing operation, the root end lifting beam (50) comprising an elongated beam body (52) comprising a first end (54) and a second end (56), a first anchoring bracket (60,60') and a second anchoring bracket (62, 621), wherein the first anchoring bracket (60,60' ) is attached to the first end of the elongated beam body and the second anchoring bracket (62, 621) is attached to the second end of the elongated beam body, the first and second anchoring brackets being configured to attach to opposite sides of the root end (17) of the wind turbine blade, and a lifting point (72) located along the elongated beam body, the lifting point (72) being configured for allowing attachment thereto by a lifting hook (82) of a lifting apparatus, such as a crane or gantry.

Description

[0001] LIFTING SYSTEM FOR WEIGHING A WIND TURBINE BLADE

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a lifting system for lifting a wind turbine blade in a horizontal orientation in the context of a weighing operation.

[0004] BACKGROUND

[0005] Wind turbine blades, essential for converting wind energy into usable power, are distinguished by their substantial size and weight, often exceeding 100 metres and weighing several tens of tons. Accurate measurement of blade weight is critical at various stages, from manufacturing and transportation to installation and maintenance, ensuring compliance with safety standards and optimizing performance.

[0006] During the lifting process for weighing wind turbine blades, challenges arise, particularly concerning the alignment of the root end lifting point relative to the blade's centre of gravity. The conventional method involves using a flat root bracket attached to the top of the root end for lifting. However, misalignment of the lifting point with the centre of gravity can lead to tilting of the blade, compromising safety and accuracy in weight measurement. Tilting occurs when the lifting point is not vertically aligned above the centre of gravity of the blade posing safety risks and complicating the weighing process.

[0007] Additionally, the lifting process can induce ovalisation of the root end due to uneven loading, further complicating weight measurement and potentially affecting structural integrity. Ovalisation occurs when the lifting point exert uneven stress distribution causing distortion and deformation at the root end. This not only complicates weight measurement but also raises concerns regarding the structural reliability of the blade.

[0008] Moreover, existing solutions for lifting wind turbine blades often suffer from a lack of versatility, as they are specifically designed for particular blade sizes, such as a certain root end diameter. These solutions may not be readily adaptable to blades of different dimensions, requiring separate equipment and procedures for each blade variant.

[0009] Existing solutions for lifting wind turbine blades often rely on manual intervention or rudimentary lifting mechanisms, which fail to adequately address the issues of misalignment-induced tilting. Thus, there is a pressing need for innovative lifting systems and methods capable of mitigating these challenges while ensuring accurate weight measurement and enhancing operational safety. In response to these challenges, the present invention introduces a novel lifting system and method designed to overcome the limitations of conventional approaches. By addressing the issues of misalignment-induced tilting and other related challenges through innovative design features and advanced control algorithms, the proposed system offers a robust and efficient solution for accurately weighing wind turbine blades during lifting operations, thereby facilitating their manufacturing, transportation, and installation processes.

[0010] SUMMARY

[0011] On this background, it may be seen as an object of the present disclosure to provide a lifting system for lifting a wind turbine blade during weighing thereof that at least mitigates the above limitations. Another object of the present disclosure is to provide a method of weighing a wind turbine blade using the lifting system. One or more of these objects may be met by aspects of the present disclosure as described in the following.

[0012] A first aspect of this disclosure relates to a root end lifting beam for securing a root end of a wind turbine blade during a weighing operation, the root end lifting beam comprising: an elongated beam body comprising a first end and a second end; a first anchoring bracket and a second anchoring bracket, wherein the first anchoring bracket is attached to the first end of the elongated beam body and the second anchoring bracket is attached to the second end of the elongated beam body, the first and second anchoring brackets being configured to attach to opposite sides of the root end of the wind turbine blade, preferably via a plurality of bushings of the root end; and a lifting point located along the elongated beam body, the lifting point being configured for allowing attachment thereto by a lifting hook of a lifting apparatus, such as a crane or gantry.

[0013] By arranging the first anchoring bracket and a second anchoring bracket on opposite sides of the root end, ovalisation of the root end during lifting is reduced or even substantially eliminated. Accordingly, the root end lifting beam can substantially maintain circularity of the root end during lifting in a weighing operation.

[0014] Additionally or alternatively, the root end lifting beam may be arranged so that, when the first and second anchoring brackets are attached to the root end of the wind turbine blade, the lifting point is arranged at a level above the centre of gravity of the wind turbine blade. When the lifting point is arranged above the centre of gravity of the wind turbine blade, tilting of the wind turbine blade about its longitudinal axis is reduced or even eliminated in the case that the lifting point is directly above the centre of gravity (in other words a line between the lifting point and the centre of gravity is vertical).

[0015] Additionally or alternatively, the lifting point may be positioned above the first and second anchoring brackets when the elongated beam body is arranged horizontally by a first distance. The first distance may be at least 2, 4, 6, 8, or preferably at least 10 cm. Accordingly, the lifting point is located at a greater vertical distance to the centre of gravity of the wind turbine blade and accordingly rotation of the blade during lifting thereof can be reduced.

[0016] Additionally or alternatively, the lifting point may be positioned within a perimeter of the root end of the wind turbine blade when the root end lifting beam is attached thereto, preferably when viewed in a longitudinal direction of the wind turbine blade. This allows a weighing operation to be performed even when the vertical space above the wind turbine blade is restricted while still reducing or eliminating tilting of the wind turbine blade when lifted.

[0017] Additionally or alternatively, the lifting point may be positioned at a second distance from a plane defined by an attachment surface of the first anchoring bracket and an attachment surface of the second anchoring bracket. The second distance may be at least 1, 2, 3, 4 or preferably at least 5 cm. Accordingly, the risk of engagement between the lifting apparatus, e.g. a wire or a hook attached to the lifting point, can be reduced, or even eliminated. Thus, the distancing may be made sufficient to accommodate the attachment means of a lifting apparatus. Additionally, the distance is preferably in a direction away from the root end of the wind turbine blade when the root end lifting beam is attached thereto.

[0018] Additionally or alternatively, the root end lifting beam may comprise repositioning means configured for adjusting and securing the position of the lifting point along the length of the elongated beam body. Such repositioning means allows aligning the lifting point vertically above the centre of gravity of the wind turbine blade. Such adjustment may reduce or even prevent tilting of the wind turbine blade about its longitudinal axis when lifting the wind turbine blade during a weighing operation.

[0019] Additionally or alternatively, the root end lifting beam may comprise securing means configured for securing the position of the lifting point along the elongated beam body. The securing means may comprise one or more of a pin attachment, bolt attachment, clamp attachment, and a threaded attachment of the lifting point to the elongated beam body but preferably comprises the pin attachment. For example, the elongated beam body may comprise a plurality of adjustment holes and the sliding element may be configured to receive an adjustment pin engaging one of the plurality of adjustment holes so as to secure the sliding element and thus the lifting point to the elongated beam body.

[0020] Additionally or alternatively, the repositioning means may comprise a sliding element. The sliding element may include the lifting point. The sliding element may be configured to allow sliding along the elongated beam body towards the first attachment bracket and / or towards the second attachment bracket. The sliding element may be configured to be secured along the length of the elongated beam body by the securing means, preferably the pin attachment. Thus, the longitudinal position of the lifting point along the elongated beam body may be adjusted and secured. The sliding element may be formed as sleeve surrounding the elongated beam body. The lifting point may be a rod fixed to the sliding element, e.g. via brackets.

[0021] Additionally or alternatively, the root end of the wind turbine blade comprises a plurality of bushings distributed circularly with a first diameter. The first and second anchoring brackets may each comprise one or more holes distributed for receiving bolts configured for securing the first and second anchoring brackets to the respective bushings of the root end of the wind turbine blade.

[0022] Additionally or alternatively, the first anchoring bracket and / or the second anchoring bracket may be telescopically arranged at the respective end(s) of the elongated beam body. The telescopic attachment allows the first and / or second anchoring bracket to extend further from or closer to the respective end(s) of the elongated beam body. Accordingly, the total length of the root end lifting beam can be adjusted accordingly and thus the root end lifting beam can be attached to different bolt circle diameters when the first and / or second anchoring brackets are telescopically adjusted accordingly.

[0023] Additionally or alternatively, the first anchoring bracket and / or the second anchoring bracket may be slidably received within a respective end of the elongated beam body so as to allow telescopic adjustment thereof. Further, the respective anchoring bracket(s) may, when the root end lifting beam is lifted via the lifting point, frictionally engage the elongated beam body so as to form a secure mechanical connection thereto.

[0024] Additionally or alternatively, the first anchoring bracket and / or the second anchoring bracket may be detachably attached to the respective end(s) of the elongated beam body, for example via a bolted connection or pin connection. This allows the replacement of one or both of the anchoring brackets to allow the attachment of the root end lifting beam to a second wind turbine blade with a root end having a second bolt circle diameter which is different from the first bolt circle diameter of the root end of the first wind turbine blade.

[0025] Additionally or alternatively, the first anchoring bracket and the second anchoring bracket may be configured to be positioned at angular positions at more than ±45°, preferably at more than ±60°, or more preferably at more than ±70°. An increase in the angular position has been found to reduce ovalisation during lifting.

[0026] Additionally or alternatively, the first anchoring bracket and the second anchoring bracket may be configured to be positioned at angular positions at less than ±90°, preferably at less than ±85°, or more preferably at less than ±80°. A decrease in angular position has been found to reduce the tilting of the wind turbine blade when lifting.

[0027] Additionally or alternatively, the first anchoring bracket and the second anchoring bracket may be configured to be positioned at angular positions in the range from ±90° to ±45°, preferably ±85° to ±60°, more preferably ±80° to ±70°, or most preferably around ±75°. The increasing preference reflects a good trade-off between preventing ovalisation during lifting, while allowing the lifting point to be positioned within the perimeter of the root end and increasing the vertical distance from the lifting point to the centre of gravity.

[0028] In the context of this disclosure, an angular position of 0° corresponds to the top position of the root end while an angular position of ±90° corresponds to the elongated beam body extending across the centre of the root end.

[0029] Additionally or alternatively, the root end lifting beam may comprise or consist essentially of a metal, such as steel or aluminium.

[0030] Additionally or alternatively, the elongated beam body may be a box beam structure and thus may have a rectangular cross-section.

[0031] A second aspect of the present disclosure relates to a kit of parts comprising a root end lifting beam according to the first aspect of the present disclosure, wherein the first anchoring bracket and / or the second anchoring bracket is / are detachably attached to the respective end(s) of the elongated beam body, for example via a bolted connection or pin connection, wherein the first and second anchoring brackets comprise bolt holes arranged circularly with a first diameter, preferably corresponding to a circular arrangement of a plurality of bushings of the root end of the wind turbine blade. The kit of parts may further comprise an additional first anchoring bracket and / or an additional second anchoring bracket, wherein the additional first and / or second anchoring bracket comprise bolt holes arranged circularly with a second diameter different from the first diameter. The second diameter may preferably correspond to a circular arrangement of a plurality of bushings of a root end of an additional wind turbine blade different from the wind turbine blade.

[0032] A third aspect of the present disclosure relates to a lifting system for securing a root end and a tip end of a wind turbine blade during a weighing operation. The lifting system comprises:

[0033] - A root end lifting beam according to the first aspect of this disclosure or a kit of parts according to the second aspect of this disclosure; and

[0034] A tip end lifting device configured for securing the tip end of a wind turbine blade during a weighing operation.

[0035] A fourth aspect of the present disclosure relates to a method of weighing a wind turbine blade. The method comprises the steps of: providing a lifting system according to the third aspect of this disclosure; providing the wind turbine blade in a substantially horizontal orientation; securing the respective anchoring brackets of the root end lifting beam to the root end of the wind turbine blade, preferably via a plurality of bushings of the root end; securing the tip end lifting device to the tip end of the wind turbine blade; attaching the lifting point of the root end lifting beam and the tip end lifting device to a lifting apparatus; lifting the wind turbine blade using the lifting apparatus; and weighing the wind turbine blade.

[0036] Additionally, the method may further comprise detaching the anchoring brackets from the root end of the wind turbine blade and from the elongated beam body, attaching the additional first and / or second anchoring brackets to the elongated beam body, securing the additional first and / or second anchoring brackets to the root end of the additional wind turbine blade, preferably via a plurality of bushings arranged circularly with the second diameter at the root end of the additional wind turbine blade.

[0037] A person skilled in the art will appreciate that any one or more of the above aspects of this disclosure and embodiments thereof may be combined with any one or more of the other aspects of this disclosure and embodiments thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Embodiments of this disclosure will be described in more detail in the following with regard to the accompanying figures. The figures show one way of implementing the present invention and are not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

[0039] Fig. 1 is a schematic perspective view of a wind turbine.

[0040] Fig. 2 is a schematic perspective view of a wind turbine blade for a wind turbine as shown in Fig. 1.

[0041] Fig. 3A is a side view of a root end lifting beam according to the present disclosure.

[0042] Fig. 3B is a perspective view of the root end lifting beam shown in Fig. 3A.

[0043] Fig. 3C is a side view of the root end lifting beam shown in Fig. 3A when secured to a root end of the wind turbine blade as for example shown in Fig. 2.

[0044] Fig. 4A is the wind turbine blade as seen towards the root end thereof.

[0045] Fig. 4B is a root end view of the wind turbine blade with a lifting apparatus secured to the root end lifting beam.

[0046] Figs. 5A-5B are side views of the root end lifting beam in different configurations to accommodate different bolt diameters.

[0047] DETAILED DESCRIPTION

[0048] In the following figure description, the same reference numbers refer to the same elements and may thus not be described in relation to all figures.

[0049] 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 which may include a tilt angle of a few degrees. The rotor includes a hub 8 and three blades 10 extending radially from the hub 8, each having a blade root 16 nearest the hub and a blade tip 14 furthest from the hub 8.

[0050] 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 an airfoil region 34 furthest away from the hub 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 8, and a trailing edge 20 facing the opposite direction of the leading edge 18. The airfoil region 34 (also called the profiled region) has an ideal or almost ideal blade shape with respect to generating lift, 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 (or the chord) of the root region 30 may be constant along the entire root region 30. The transition region 32 has a transitional profile gradually changing 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 with increasing distance r 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. The width of the chord decreases with increasing distance r from the hub. A shoulder 38 of the blade 10 is defined as the position, where the blade 10 has its largest chord length. The shoulder 38 is typically provided at the boundary between the transition region 32 and the airfoil region 34.

[0051] It should be noted that the chords of different sections of the blade normally do not lie in a common plane, since the blade may be twisted and / or curved (i.e. pre-bent), thus providing the chord plane with a correspondingly twisted and / or curved course, this being most often the case in order to compensate for the local velocity of the blade being dependent on the radius from the hub.

[0052] On Fig. 3A, a root end lifting beam 50 according to the present disclosure is shown. The root end lifting beam 50 is for securing the root end 17 of the wind turbine blade as illustrated in Fig. 2 during a weighing operation which will be described in greater detail below. The root end lifting beam 50 comprises an elongated beam body 52 with a first end 54 and a second end 56. The root end lifting beam 50 further comprises a first anchoring bracket 60 and a second anchoring bracket 62. The first anchoring bracket 60 is attached to the first end 54 of the elongated beam body 52 and the second anchoring bracket 62 is attached to the second end 56 of the elongated beam body 52.

[0053] The root end lifting beam 50 also includes a sliding element 70 located along the elongated beam body 52 between the first anchoring bracket 60 and the second anchoring bracket 62. The sliding element 70 is configured to allow sliding along the elongated beam body 52 towards the first attachment bracket 60 and towards the second attachment bracket 62. The elongated beam body 52 comprises a plurality of adjustment holes 58 distributed along the length of the elongated body. An adjustment pin 74 can thus secure the sliding element 70 to one of the adjustment holes 58.

[0054] The sliding element 70 has a lifting point 72 configured for allowing attachment thereto by a lifting hook of a lifting apparatus, such as a crane or gantry. The lifting point 72 is positioned above the first and second anchoring brackets 60, 62 by a distance Di, preferably of at least 10 cm, in a vertical direction V when the elongated beam body 52 is arranged in a horizontal direction H.

[0055] Each of the first and second anchoring brackets 60, 62 comprises an attachment surface which is arranged on the side of the anchoring brackets opposite of the view of Fig. 3A and can be better seen on Fig. 3C. As shown in Fig. 3C, each of the first and second anchoring brackets 60, 62 comprises bolt holes 66 extending through the first and second anchoring brackets 60, 62 to the attachment surface 64. The bolt holes 66 can receive bolts 68 for engaging bushings 49 of the root end 17.

[0056] As also seen in Fig. 3C, the lifting point 72 is positioned at a distance D2, preferably of at least 5 cm, from a plane defined by the attachment surfaces 64 of the first and second anchoring brackets 60, 62. Additionally, the distance D2 is in a direction away from the root end 17 of the wind turbine blade 10 when the root end lifting beam 50 is attached thereto as shown in Fig. 3C.

[0057] Turning to Figs. 4A-4B, the wind turbine blade 10 is shown when viewed towards the root end 17. As visible through the root end 17, two shear webs 46 are arranged within the interior of the wind turbine blade 17. Further, the wind turbine blade is pre-bent and thus the tip end 15 is also visible. A tip end lifting device 90, in this case a strap, of a lifting system is shown near the tip end 15. The lifting system further comprises the root end lifting beam 50 which is secured to respective bushings 49 of the root end 17 of the wind turbine blade 10 by inserting bolts 68 through bolt holes 66 of the first and second anchoring brackets 60, 62 and engaging these bolts 68 with the bushings 49. The first anchoring bracket and the second anchoring bracket are attached to opposite sides of the root end 17 at angular positions ai of ±85°. Accordingly, the root end lifting beam 50 is arranged above the centre of the root end CR reducing tilting. As seen, when the root end lifting beam is secured to the root end, the lifting point 72 is positioned within a perimeter of the root end 17 of the wind turbine blade 10 and even within the diameter 0i of the bushings 49. Further, the lifting point is arranged at a level above the centre of gravity CG of the wind turbine blade 10. Due to the complex shape of the wind turbine blade, the centre of gravity CG is offset from the centre of the root end CR and can vary between blade types, for example due to the amount of prebend, forward sweep, backward sweep, and the mass distribution within the wind turbine blade etc. In an exemplary adjustment method, the sliding element 70 can then be adjusted by disengaging the adjustment pin 74, sliding the sliding element 70 towards the second end 56 until the lifting point 72 is substantially vertically above the centre of gravity CG. The sliding element 72 is then secured by reengaging the adjustment pin 74. Turning to Fig. 4B, the wind turbine blade is suspended in a substantially horizontal orientation from the root end lifting beam 50 via a lifting hook 82 of the lifting apparatus (not shown but is typically an overhead gantry crane in a factory setting) attached to the lifting point 72. Once the wind turbine blade 10 is lifted and in a suspended and horizontal configuration, the weighing operation is performed by weighing means 84, such as load cells.

[0058] Turning to Figs. 5A-5B, the first and second anchoring brackets 60, 62 can be adapted to different bolt diameters 0i, 02. This can be achieved for example by slidingly receiving the first anchoring bracket 60 and the second anchoring bracket 62 at the respective ends 54, 56 of the elongated beam body 52 to allow telescopic adjustment. The telescopic attachment allows the first and / or second anchoring bracket to extend further from or closer to the respective end(s) of the elongated beam body. Accordingly, the total length of the root end lifting beam can be adjusted accordingly. The bolt holes 66 may advantageously be provided as horizontal slots (not shown) to further accommodate different bolt diameters. The first and second anchoring brackets 60, 62 may be secured to the respective ends by respective pins 69 and additionally, when the root end lifting beam 50 is lifted via the lifting point 72, frictiona lly engage the elongated beam body 52 so as to form a secure mechanical connection thereto.

[0059] Alternatively, the first anchoring bracket and the second anchoring bracket 60, 62 are detachably attached to the respective ends 54, 56 of the elongated beam body 52 via the pin 69. This allows the replacement of the first and second anchoring brackets 60, 62 with an additional first anchoring bracket 60' and an additional second anchoring bracket 62'. The additional first and second anchoring bracket 60', 62' comprise bolt holes 66 arranged circularly with a second diameter 02 different from, in this example greater than, the first diameter 0i. Accordingly, the additional first and second anchoring bracket 60', 62' allow the attachment of the root end lifting beam 50 to a second wind turbine blade with a root end having the second bolt diameter 02 which is different from the first bolt diameter 0i of the root end 17 of the first wind turbine blade 10 shown in Fig. 4A.

[0060] LIST OF REFERENCES

[0061] 2 wind turbine 0 bolt diameter

[0062] 4 tower V vertical direction

[0063] 6 nacelle H horizontal direction

[0064] 8 hub Di distance

[0065] 10 blade D2 distance

[0066] 13 shell CG centre of gravity

[0067] 14 blade tip OR centre of root end

[0068] 15 tip end

[0069] 16 blade root

[0070] 17 root end

[0071] 18 leading edge

[0072] 20 trailing edge

[0073] 30 root region

[0074] 32 transition region

[0075] 34 airfoil region

[0076] 36 tip region

[0077] 38 shoulder

[0078] 46 shear web

[0079] 49 bushing

[0080] 50 root end lifting beam

[0081] 52 elongated beam body

[0082] 54 first end

[0083] 56 second end

[0084] 58 adjustment hole

[0085] 60 first anchoring bracket

[0086] 62 second anchoring bracket

[0087] 64 attachment surface

[0088] 66 bolt hole

[0089] 68 bolts

[0090] 69 pin

[0091] 70 sliding element

[0092] 72 lifting point

[0093] 74 adjustment pin

[0094] 82 lifting hook

[0095] 84 load cell

[0096] 90 tip end lifting device

Claims

CLAIMS1. A root end lifting beam (50) for securing a root end (17) of a wind turbine blade (10) during a weighing operation, the root end lifting beam comprising:- an elongated beam body (52) comprising a first end (54) and a second end (56); a first anchoring bracket (60, 60') and a second anchoring bracket (62, 62'), wherein the first anchoring bracket is attached to the first end of the elongated beam body and the second anchoring bracket is attached to the second end of the elongated beam body, the first and second anchoring brackets being configured to attach to opposite sides of the root end of the wind turbine blade; and- a lifting point (72) located along the elongated beam body, the lifting point being configured for allowing attachment thereto by a lifting hook (82) of a lifting apparatus, such as a crane or gantry.

2. A root end lifting beam according to claim 1, wherein the root end lifting beam is arranged so that, when the first and second anchoring brackets are attached to the root end of the wind turbine blade, the lifting point is arranged at a level above the centre of gravity (CG) of the wind turbine blade.

3. A root end lifting beam according to any one of the previous claims, wherein the lifting point is positioned above the first and second anchoring brackets when the elongated beam body is arranged horizontally by a first distance (Di).

4. A root end lifting beam according to any one of the previous claims, wherein the lifting point is positioned within a perimeter of the root end of the wind turbine blade when the root end lifting beam is attached thereto.

5. A root end lifting beam according to any one of the previous claims, wherein the lifting point is positioned at a second distance (D?) from a plane defined by an attachment surface (64) of the first anchoring bracket and an attachment surface (64) of the second anchoring bracket.

6. A root end lifting beam according to any one of the previous claims, wherein the root end lifting beam comprises repositioning means (70) configured for adjusting and securing the position of the lifting point along the length of the elongated beam body.

7. A root end lifting beam according to any one of the previous claims, wherein the root end lifting beam comprises securing means (74) configured for securing the position of the lifting point along the elongated beam body, preferably the securing means comprises oneor more of a pin atachment, bolt atachment, clamp atachment, a friction fit atachment, and a threaded atachment of the lifting point to the elongated beam body.

8. A root end lifting beam according to any one of the previous claims, wherein the repositioning means comprises a sliding element (70) including the lifting point, wherein the sliding element is configured to allow sliding along the elongated beam body towards the first atachment bracket and / or towards the second atachment bracket.

9. A root end lifting beam according to any one of the previous claims, wherein the sliding element is configured to be secured along the length of the elongated beam body by a pin atachment (74).

10. A root end lifting beam according to any one of the previous claims, wherein the first anchoring bracket and / or the second anchoring bracket is / are telescopically arranged at the respective end(s) of the elongated beam body.

11. A root end lifting beam according to claim 10, wherein the first anchoring bracket and / or the second anchoring bracket is / are slidably received within a respective end of the elongated beam body so as to allow telescopic adjustment thereof.

12. A root end lifting beam according to any one of the previous claims, wherein the first anchoring bracket and / or the second anchoring bracket is / are detachably atached to the respective end(s) of the elongated beam body, for example via a bolted connection or pin connection.

13. A kit of parts comprising: a root end lifting beam according to claim 12, wherein the first and second anchoring brackets (60, 62) comprises bolt holes arranged circularly with a first diameter (0i); and an additional first anchoring bracket (60') and / or an additional second anchoring bracket (62'), wherein the additional first and / or second anchoring bracket comprise bolt holes arranged circularly with a second diameter (0?) different from the first diameter.

14. A lifting system for securing a root end and a tip end of a wind turbine blade during a weighing operation, the lifting system comprising: a root end lifting beam according to claims 1-12 or a kit of parts according to claim 13; anda tip end lifting device (90) configured for securing the tip end of a wind turbine blade during a weighing operation.

15. A method of weighing a wind turbine blade, comprising the steps of: providing a lifting system according to claim 14; - providing the wind turbine blade in a substantially horizontal orientation; securing the respective anchoring brackets of the root end lifting beam to the root end of the wind turbine blade; securing the tip end lifting device to the tip end of the wind turbine blade; attaching the lifting point of the root end lifting beam and the tip end lifting device to a lifting apparatus; lifting the wind turbine blade using the lifting apparatus; and weighing the wind turbine blade, preferably via one or more load cells.

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