Blade clamping tool for wind turbine blade

Abstract

A blade clamping tool for a wind turbine blade, said blade clamping tool comprising: a first clamping element adapted to be in contact with a first surface of a wind turbine blade when the wind turbine blade is clamped in the blade clamping tool, a second clamping element adapted to be in contact with a second surface of the wind turbine blade when the wind turbine blade is clamped in the blade clamping tool, said second surface being opposite to said first surface, a c-formed bracket comprising a first leg connected to the first clamping element, a second leg connected to the second clamping element, and an intermediate part connecting the first and second leg. The first leg of the c-formed bracket comprises a first pivot mechanism arranged to pivot the first clamping element away from the second clamping element and the intermediate part comprises a second pivot mechanism arranged to rotate the first leg towards the second clamping element. In this way, a blade clamping tool is provided which allows for a fast and simple folding of the blade clamping tool prior to transport and a fast and simple unfolding of the blade clamping tool prior to use.

Description

[0001] Blade clamping tool for wind turbine blade

[0002] The current invention relates to a blade clamping tool for a wind turbine blade, said blade clamping tool comprising: a first clamping element adapted to be in contact with a first surface of a wind turbine blade when the wind turbine blade is clamped in the blade clamping tool, a second clamping element adapted to be in contact with a second surface of the wind turbine blade when the wind turbine blade is clamped in the blade clamping tool, said second surface being opposite to said first surface, and a c-formed bracket comprising a first leg connected to the first clamping element, a second leg connected to the second clamping element, and an intermediate part connecting the first and second leg.

[0003] Description of related art

[0004] Blade clamping tools for wind turbine blades, sometimes known as blade yokes, are well known in the art of wind turbine repairs, construction and assembly. Typically, when an operation is being done on a wind turbine, all the necessary support equipment needs to be transported to the site. This includes the blade yokes and other equipment as well. For land-based sites, the equipment typically needs to be transported via a truck. For offshore sites, the equipment would be transported by a ship or barge or other floating vessel. To make the transportation easier, it is often desired to arrange the equipment in standard shipping containers.

[0005] When transporting blade yokes which have a large and unregular shape, numerous difficulties are experienced as the equipment cannot be transported in the same configuration as it is used. Usually, in order to overcome this problem, the equipment is arranged to be disassembled for transport and then reassembled at the operation site. Once the lifting operation is finished, then the equipment needs to be disassembled and stored for transport again. In some prior art systems, some parts can be foldable and / or detachable. Disassembling and re-assembling consumes time and effort. Furthermore, it also requires multiple smaller lifting operations in order to set all the parts together due to the weight of each component which cannot be lifted by a single worker. Also counterweights which are often used by blade yokes are heavy and must be assembled and disassembled in each operation. This issue is becoming ever more relevant as wind turbines grow in size, therefor requiring ever larger support equipment.

[0006] An example of a blade yoke is disclosed in EP2873641A1. In this particular example, the yoke has a double c-formed structure, and each c-formed bracket has a detachable connection between the upper and lower section for transportation purposes. Such detachable systems require multiple parts to be disassembled and stored elsewhere. Another problem is that this operation can’t be done in a single step, so there are a lot of time-consuming steps required to store and transport the blade yoke.

[0007] Another example is EP4276305A2 which discloses a blade yoke which is foldable for transportation purposes. This blade yoke also has a double c-formed structure. In additional to the lifting yoke, it comprises a set of foldable and telescopic arms with thrusters mounted at the end of the arms to help control the position of the blade. While the telescopic arms are shown to be foldable, the remainder of the blade yoke still needs to be disassembled during transport.

[0008] Another example, EP4345049A1 , discloses a foldable blade yoke which can be packed to fit within a standard container and then expanded for use. This tool comprises two c-formed brackets and additionally two locking means which can hold the c-formed brackets in place when they are unfolded.

[0009] Summary of the invention

[0010] It is therefore a first aspect of the current invention to provide a blade clamping tool which can be folded with minimum structural adjustments.

[0011] A second aspect of the current invention is to provide a blade clamping tool which can be prepared for transport quicker than prior art blade clamping tools.

[0012] These aspects are provided at least in part by a blade clamping tool as mentioned in the introductory paragraph characterized in that the first leg of the c-formed bracket comprises a first pivot mechanism arranged to pivot the first clamping element away from the second clamping element and in that the intermediate part comprises a second pivot mechanism arranged to rotate the first leg towards the second clamping element. In this way, a blade clamping mechanism is provided which can be folded in a simple and effective manner.

[0013] In some embodiments, the first and second pivot mechanisms have a locked position where the first and second pivot mechanisms are locked and an unlocked position where the first and second pivot mechanisms are free to pivot. In some embodiments, the locked and unlocked positions are provided by first and second locking mechanisms. In some embodiments, the locked and unlocked positions are provided by pin based locking mechanisms. In some embodiments, a third locking mechanism is provided to lock the position of the first clamping element relative to the second leg. In some embodiments, the third locking mechanism connects the first clamping element to the second leg. In some embodiments, the connection is provided by a pin mechanism.

[0014] In some embodiments, the first and / or second leg is / are arranged at an angle of between -20 and +20 degrees to the horizontal when a blade is clamped in the blade clamping tool and the blade clamping tool is resting on a support surface. In some embodiments, the first and / or second pivot mechanisms have a range of motion which is at least 60 degrees, at least 70 degrees or at least 80 degrees. In some embodiments, the distance between a connection between the first leg and the intermediate part and a connection between the second leg and the intermediate part is greater than 10% of the chord length of a wind turbine blade which is suitable for being clamped in the blade clamping tool.

[0015] In some embodiments, a pivot axis of the first pivot mechanism is placed at a first horizontal distance from the connection between the first leg and the first clamping element and at a second horizontal distance from the connection between the first leg and the intermediate part. In some embodiments, the distance is greater than 0.5m. In some embodiments the pivot axis of the first pivot mechanism is a horizontal pivot axis. In some embodiments, the pivot axis of the first pivot mechanism is arranged parallel to a longitudinal axis of a wind turbine blade, when the wind turbine blade is clamped in the blade clamping tool. In some embodiments the horizontal distance from the pivot axis of the first pivot mechanism to the connection between the first leg and the intermediate part is at least 25%, at least 30% or at least 35% of the horizontal distance between the connection between the first clamping mechanism and the first leg and the connection between the first leg and the intermediate part.

[0016] In some embodiments, a pivot axis of the second pivot mechanism is placed at a vertical distance from the connection between the first leg and the intermediate part and at a vertical distance from the connection between the second leg and the intermediate part. In some embodiments, the distance is greater than 0.5m. In some embodiments the pivot axis of the second pivot mechanism is a horizontal pivot axis. In some embodiments, the pivot axis of the second pivot mechanism is arranged parallel to a longitudinal axis of a wind turbine blade, when the wind turbine blade is clamped in the blade clamping tool. In some embodiments the vertical distance from the pivot axis of the second pivot mechanism to the connection between the first leg and the intermediate part is at least 25%, at least 30% or at least 35% of the distance between the connection between the second leg and the intermediate part and the connection between the first leg and the intermediate part.

[0017] In some embodiments, the blade clamping tool consists of a single C-formed bracket. In some embodiments, the blade clamping tool comprises two C-formed brackets, each C-formed bracket being arranged to have first and second pivot mechanisms as described above.

[0018] In some embodiments, the blade clamping tool further comprises: a first extension arm extending from a first end of the first clamping element, and a second extension arm extending from a second end of the first clamping element.

[0019] In some embodiments, the first and second extension arms are pivotally connected to the first clamping element about first and second pivot axes respectively and in that the first and second extension arms are arranged to be able to pivot between two positions, an extended position and a folded position. In some embodiments, the first and second pivot axes are horizontal pivot axes such that the extension arms start to pivot in an upwards direction when moving from the extended position towards the folded position. In some embodiments, the first extension arm and the second extension arm can each rotate more than 150 degrees, more than 160 degrees or more than 170 degrees around first and second pivot axes respectively. In some embodiments, the first extension arm and the second extension arm are arranged to extend in a longitudinal direction of the first clamping element in the extended position of the first and second extension arms.

[0020] In some embodiments, the blade clamping tool further comprises: a first counterweight located near a first end of the first clamping element, and a second counterweight located near a second end of the first clamping element.

[0021] In some embodiments, the first and second counterweights are pivotally connected to the first clamping element via first and second pivot axes respectively and in that the first and second counterweights are arranged to be able to pivot between an extended position and a folded position. In some embodiments, the first and second pivot axes of the counterweights are vertical pivot axes. In some embodiments, the counterweights move inwards, towards a central portion of the blade clamping tool, when moving from the extended position to the folded position.

[0022] In some embodiments, the first counterweight and the second counterweight are arranged to extend in a horizontal direction. In some embodiments, the first and second counterweights extend in a direction which is perpendicular to a longitudinal direction of the first clamping element when in their extended positions. In some embodiments, the first counterweight and the second counterweight are arranged to be able to rotate at least 80 degrees, at least 130 degrees, or at least 170 degrees around their pivot axes.

[0023] In some embodiments, the blade clamping tool further comprises a first lifting point arranged on one side of a central axis of the first clamping element and a second lifting point arranged on another side of the central axis of the first clamping element, said first and second points being spaced apart by a horizontal distance. In some embodiments, the horizontal distance is greater than 0.25m, greater than 0.35m or greater than 0.45m. According to this specification a lifting point is defined as a point which is suitable for connecting a lifting wire of a crane to. In some embodiments, the crane lifting wire is connected to both the first and second points via a Y sling.

[0024] In some embodiments, the first and second lifting points are provided on a lifting beam which is attached to the first clamping element, said lifting beam comprising a longitudinal axis which is arranged perpendicular to a central axis of the first clamping element. In some embodiments, the lifting beam is detachably attached to the first clamping element. According to this specification, a central axis of the first clamping element is a horizontal axis which is arranged parallel to a longitudinal axis of the first clamping element and passing through the centre of gravity of the first clamping element. In some embodiments, the first and second lifting points are provided on either side of a horizontal axis arranged parallel to a longitudinal axis of the first clamping element and which passes through the centre of gravity of the portion of the blade clamping tool which is arranged outwardly of the first pivot mechanism, thereby including the first clamping element, the extension arms and the counterweights.

[0025] The current invention also relates to a method for folding a blade clamping tool according to any one of the embodiments described above, said method comprising the steps of: a. rotating a portion of the first leg arranged outwardly of the first pivot mechanism, at least 60 degrees in an initial upwards direction away from the second clamping element, and b. rotating a portion of the intermediate part arranged upwardly of the second pivot mechanism at least 60 degrees in an initial outward direction towards the second clamping element.

[0026] In some embodiments, the method further includes the step of rotating the first and second extension arms, upwards and then towards the C-shaped bracket about horizontal axes.

[0027] In some embodiments, the method further comprises the step of rotating the first and second counterweight, towards the C-formed bracket about vertical axes. In some embodiments, the extension arms and counterweights are rotated prior to pivoting the first clamping element. In some embodiments, the extension arms and counterweights are rotated after pivoting the first clamping element.

[0028] In some embodiments, the rotation about the first pivot mechanism and the rotation about the second pivot mechanism are performed at the same time, so that the first clamping element rotates outwardly due to the rotation about the first pivot mechanism and downwardly due to the rotation about the second pivot mechanism. In some embodiments, the direction of rotation of the first and second pivot mechanisms is in opposite directions.

[0029] In some embodiments, the method further comprises the step of connecting a lifting wire from a crane to the first clamping element, said crane supporting the first clamping element and lowering the first clamping element in a controlled manner.

[0030] In some embodiments, the crane lifts the first clamping element slightly before unlocking the first and second pivot mechanisms, before lowering the first clamping element.

[0031] In some embodiments, the step of connecting the lifting wire to the first clamping element, comprises the step of connecting the lifting wire to two points on the first clamping element, said two points being spaced in a direction which is perpendicular to a longitudinal extension of the first clamping element. In some embodiments, at least one of the two points is located further away from the intermediate part in a horizontal direction, than the central axis of the first clamping element. In some embodiments, said at least one of the two points is located at a distance of at least 0.25m, at least 0.35m or at least 0.45m from the central axis of the first clamping element. In some embodiments, the other of said two points is located closer to the intermediate part than the central axis of the first clamping element.

[0032] In some embodiments, where the blade clamping tool comprises a first and a second extension arm and / or a first and a second counterweight, the blade clamping tool is folded first and then the extension arms and / or the counterweights are folded in. In this way, the extension arms and / or the counterweights are located in a position closer to the ground prior to having to move them.

[0033] In some embodiments, the steps of the method are reversed to unfold the blade clamping tool.

[0034] The current specification also discloses a second invention related to a clamping mechanism of a blade clamping tool. This second invention could form the basis for a divisional application.

[0035] The clamping mechanism needs to be able to displace a clamping element of the blade clamping tool which engages with the surface of the blade during a lifting operation between an active position where it engages with the surface of the blade to hold the blade in the blade clamping tool and a retracted position where it is displaced away from the surface of the blade such that the blade can be inserted into the blade clamping tool.

[0036] Such clamping mechanisms are known in the art. One example is disclosed in CN112390136A which discloses two separate hydraulic displacement mechanisms, one attached to a first C-formed bracket and one attached to a second C-formed bracket. W003100249A1 discloses a similar adjustable mechanism. Applicant’s own disclosure W02020 / 053391 , which is incorporated by reference in this specification, discloses a blade yoke with a single C-formed bracket and upper and lower beams. Clamping surfaces are arranged at each end of the upper and lower beams. The upper and / or lower beams of the blade yoke are arranged pivotably about a horizontal axis so that the upper and / or lower beams can be displaced up and down with respect to each other.

[0037] According to the second invention, an alternative mechanism is provided which is light weight when compared to blade yokes having two C-formed brackets and which has a large adjustment range and simple construction when compared to single C-formed bracket blade yokes. Some examples of a blade clamping tool according to the second invention are provided by the following examples:

[0038] Ex. 1. A blade clamping tool for a wind turbine blade comprising: a. a first clamping element adapted to be arranged on a first side of a wind turbine blade when a wind turbine blade is arranged in the clamping tool, b. a second clamping element adapted to be arranged on a second side of the wind turbine blade, c. a single c-formed bracket connecting the first and second clamping element, d. a first blade contacting surface attached to the first clamping element on one side of the c-formed bracket, and e. a second blade contacting surface attached to the first clamping element on a second side of the c-formed bracket, f. characterized in that blade clamping tool further comprises a first vertically arranged actuator for adjusting the vertical distance between the first blade contacting surface and a surface of the wind turbine blade and a second vertically arranged actuator for adjusting the vertical distance between the second blade contacting surface and a surface of the wind turbine blade.

[0039] Ex. 2. A blade clamping tool according to claim 1, characterized in that the first vertically arranged actuator and the second vertically arranged actuator are connected to the first clamping element via detachable connections, for example pinned connections.

[0040] Ex. 3. A blade clamping tool according to claim 1, characterized in that the detachable connections have at least two different fixation or connection points spaced apart from each other in a vertical direction to further adjust the vertical distance between a surface of the wind turbine blade and the first and second blade contacting surfaces.

[0041] The current specification also discloses a third invention related to a blade clamping tool with a leading edge support mechanism for a blade arranged in the blade clamping tool. This invention could form the basis for an additional divisional application.

[0042] Blade yokes which have leading edge support mechanisms are known in the art. One example is applicant’s own disclosure, EP3849929B1 , which discloses a transverse bar which has adjustable pads which are arranged to support the leading edge of the blade when the blade is arranged in the yoke.

[0043] According to the third invention, an alternative leading edge support mechanism is provided which has a large range of adjustment and is light weight and simple.

[0044] Some examples of a wind turbine blade clamping tool according to the third invention are provided by the following examples.

[0045] Ex. 11. A blade clamping tool for a wind turbine blade comprising: a. a first clamping element adapted to be arranged on a first side of a wind turbine blade when a wind turbine blade is arranged in the clamping tool, b. a second clamping element adapted to be arranged on a second side of the wind turbine blade, c. a c-formed bracket connecting the first and second clamping element, d. a first blade contacting surface attached to the first clamping element on one side of the c-formed bracket, and e. a second blade contacting surface attached to the first clamping element on a second side of the c-formed bracket, f. characterized in that said blade clamping tool further comprises g. a first and a second supporting arm, a first end of said first and second supporting arms being pivotably connected to the c-formed bracket, h. a first and a second pad for supporting a leading edge of a wind turbine blade, said first and second pads being connected to a second end of the first and second supporting arms respectively, and i. first and second locking mechanisms for locking an angular position of the first and second supporting arms respectively with respect to the c-formed bracket.

[0046] Ex. 12. A blade clamping tool according to example 11 , characterized in that said locking mechanism comprises a pinned connection with a number of discreet locking positions.

[0047] Ex. 13. A blade clamping tool according to example 11 or 12, characterized in that the c-formed bracket is the only c-formed bracket of the blade clamping tool.

[0048] It should be emphasized that the term "comprises / comprising / comprised of" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0049] Brief description of the drawings

[0050] Figure 1 is a perspective view of a blade clamping tool according to the invention in a working configuration.

[0051] Figure 2 is a perspective view of the blade clamping tool of figure 1, seen from a different angle.

[0052] Figure 3 is a zoomed perspective view of an upper blade clamping element as defined by the area marked with III in figure 2.

[0053] Figure 4 is a zoomed perspective view of a leading edge support mechanism as defined by the area marked with IV in figure 2.

[0054] Figures 5 and 6 show two different perspective views of a first step in a first folding procedure of the blade clamping tool of figure 1. Figures 7 and 8 show two different perspective views of a second step in the first folding procedure of the blade clamping tool of figure 1.

[0055] Figures 9 and 10 show two different perspective views of a final step in the first folding procedure of the blade clamping tool of figure 1.

[0056] Figures 11 and 12 show two different perspective views of a first step in a second folding procedure of the blade clamping tool of figure 1.

[0057] Figures 13 and 14 show two different perspective views of a second step in a second folding procedure of the blade clamping tool of figure 1.

[0058] Figures 15 to 17 show perspective views of another embodiment of a blade clamping tool according to the invention and three steps in an alternative method of folding the blade clamping tool.

[0059] In the following, the invention will be described in greater detail with reference to embodiments shown by the enclosed figures. It should be emphasized that the embodiments shown are used for example purposes only and should not be used to limit the scope of the invention.

[0060] Detailed description of the embodiments

[0061] Figures 1 and 2 show a foldable blade clamping tool 1 according to the present invention. Figures 1 and 2 also show features of the second and third inventions as described above.

[0062] The blade clamping tool is arranged to be securely clamped to a blade (not shown) of a wind turbine so that a crane can lift the blade via the blade clamping tool. The blade clamping tool comprises a first clamping element 2, adapted to be arranged to be in contact with a first side of the blade and a second clamping element 4 arranged to be in contact with a second side of the blade. The first clamping element 2 comprises a beam 5 with a first blade contacting surface 6 arranged at a first end of the beam and a second blade contacting surface 7 arranged at the second end of the beam. The second clamping element 4 also comprises a beam 8 with a first blade contacting surface 9 arranged at a first end of the beam and a second blade contacting surface 10 arranged at a second end of the beam. The blade clamping tool further comprises a third blade contacting surface 40 which is arranged to be in contact with a trailing edge of the blade.

[0063] A c-formed bracket 30 connects the first clamping element 2 and the second clamping element 4. The c-formed bracket 30 comprises a first leg 32 connected to the first clamping element 2 and a second leg 36 connected to the second clamping element 4. An intermediate part 34 of the c-formed bracket 30 provides a connection between the first leg 32 and the second leg 36. A first pivot mechanism 33 is provided in the first leg, at a position between a connection between the first leg and the intermediate part and a connection between the first leg and the first clamping element. This first pivot mechanism is arranged to allow an outer portion of the first leg together with the first clamping element to pivot upwardly, away from the second leg and second clamping element. A second pivot mechanism 35 is arranged in the intermediate part 34 between the first and second legs. The second pivot mechanism 35 allows an upper portion of the intermediate part, together with the first leg 3 and first clamping mechanism 2, to rotate downwards and towards the second clamping element 4. By first folding the first clamping mechanism upwardly via the first pivot mechanism and then pivoting the first leg and first clamping mechanism downwardly via the second pivot mechanism, the blade clamping tool is able to be folded for transporting the blade clamping tool 1. This is also an easy operation to do with a crane, since all the motions can be effected just by lifting / lowering in a vertical direction. The crane can therefore fold the tool at the end of the lifting operation.

[0064] Furthermore, the blade clamping tool comprises a first extension arm 11 and a second extension arm 12. An outer portion of these arms can be connected to taglines in order to help control the position of the blade during a lifting operation. The first extension arm 11 is connected pivotably to a first end point of the beam of the first clamping element with a pivot mechanism 14 which allows the first extension arm to pivot around the first end point about a horizontal axis which is perpendicular to the longitudinal axis of the beam. Similarly, the second extension arm 12 is pivotably connected to a second end point on the beam of the first clamping element with a pivot mechanism 16 which allows the second extension arm to pivot around the second end point about a horizontal axis which is perpendicular to the longitudinal axis of the beam of the first clamping mechanism. By rotating the extension arms 11 , 12 via the pivot mechanisms 14, 16 creates a foldable effect which makes it easier to transport the blade clamping tool by reducing its overall length, without needing to disassemble the extension arms.

[0065] The first clamping element 2 also comprises a first counterweight 20 and a second counterweight 22. When the blade is lifted, according to the weight and the size of the blade and how it is arranged in the blade clamping too, weight adjustment is often necessary to keep the blade level. This is performed via the counterweights. The first counterweight 20 is placed at the first end of the beam of the first clamping element 2 in a transverse direction and opposite the c-formed bracket. The first counterweight 20 is pivotably connected to the first clamping element 2 and can rotate with a pivot mechanism 24 inwardly and towards the beam of the first clamping element about a vertical axis to reduce the overall width of the system while being transported. Similarly, the second counterweight 22 is placed at the second end of the beam of the first clamping element 2 in a transverse direction and again opposite the c-formed bracket. The second counterweight 22 is pivotably connected with a pivot mechanism 26 to the first clamping element 2 and can rotate inwards and towards the beam of the first clamping element 2 about a vertical axis. It can be seen from the figures that the extension arms are folded first to make room for the counterweights, then the counterweights are folded afterwards.

[0066] In Figures 2 and 3, another detail of the blade clamping tool of this invention can be seen. More particularly, the first clamping element 2 comprises a length adjusting mechanism 100 which can adjust the vertical position of a first blade contacting surface 101 in order to come in contact with the surface of the wind turbine blade and hold it properly for lifting. The blade contacting surface is pivotally connected to an actuator 102 of the length adjusting mechanism with a pivotable connection 106. Furthermore, the actuator 102 is connected with a pin connection 104 to the first clamping element 2. The pin connection 104 has multiple positions arranged at multiple vertical levels providing extra pin height adjustment which gives further adjusting length to the length adjusting mechanism 100.

[0067] In Figures 2 and 4 another detail of this invention can be seen. More particularly, an intermediate part 34, 200 of the C-formed bracket 30 is provided with two supporting arms 202, one on each side of the C-formed bracket 30, each being provided with a supporting pad 204 adapted to support a leading edge of a wind turbine blade held by the blade clamping tool 1. The supporting arms 202 are pivotably connected to the C-formed bracket 30 which makes the supporting arms 202 adjustable to move towards or away from the blade to accommodate various blade sizes. Also, the supporting pads 204 are pivotally connected to the supporting arms 202 and can rotate for better contact with the leading edge of the blade. The supporting arms are connected to the c-formed bracket via a pivot mechanism. Said pivot mechanism is provided with a pin locking mechanism, where the supporting arms can be locked in different positions, by engaging a pin with different pin holes.

[0068] In Figures 5 to 10, a first folding procedure is illustrated. Usually, the procedure is performed when the clamping tool has been put on the ground after a lifting procedure has been finished. The tool in this embodiment, therefore comprises a set of legs 310 which are used to support the tool while it is placed on the ground. Usually, a crane is used for this operation. It can be the same crane as the one which is used to lift the blades via the blade clamping tool up to the wind turbine. It could also be a temporary crane, for example a smaller mobile crane mounted on a truck. In this illustration, as seen in Figs. 5 and 6, a first step is to lift the first clamping element 2 by connecting the crane’s hook (not shown) to a hook point 302 so that the weight of the first clamping element is supported by the crane. Depending on the forces required, the crane hook can be connected to different points 302, 304 on the blade clamping tool. The first pivot mechanism 33 can then be unlocked and the first clamping element lifted. This will rotate the first clamping element 2 upwards and away from the second clamping element. More particularly, this will pivot the first clamping element 2 about a pivot axis A of the pivot mechanism 33 which is parallel to the longitudinal direction of the first clamping element 2. After having lifted the clamping element 2 upwards, as seen in Figs. 7 and 8, the first pivot mechanism 33 is locked in position to lock the angle between a rear portion of the first leg of the C-formed bracket and a forward portion of the first leg together with the first clamping mechanism. The next step is to again lift the first clamping mechanism via the crane until the weight of the first clamping element is again supported by the crane. The second pivot mechanism can then be unlocked. The crane can then lower the first clamping element to rotate the first clamping element 2 downwards until the first leg 32 is facing downwards. During this rotation, an upper part of the intermediate part of the C-formed bracket rotates about an axis B, which is parallel to axis A and to the longitudinal direction of the first clamping element 2, towards the ground and in a direction where the first clamping element 2 moves towards the second clamping element 4.

[0069] As seen in Figs. 9 and 10, another step of the first folding procedure is to rotate the extension arms 11 ,12 inwards using their pivot mechanisms 14,16. The crane’s hook can be connected to a hook connection point 306 on the arm and the arm can then be lifted upwards until it reaches a 90° angle facing upwards and then lowered to fold the arm inwardly. The arms are rotated around a rotation axis C and C’ for each arm, said axis being horizontal and perpendicular to the longitudinal direction of the first clamping element 2.

[0070] After the extension arms 11 ,12 have been rotated, the counterweights 20,22 are rotated inwards. The rotation is again done via their pivot mechanisms 24, 26 around rotation axes D, D’ which are vertical. The counterweights are being pushed or pulled around the axes D and D’ so that they can rotate inwardly, until the counterweights do not extend out further than the point of the C-formed bracket which is furthest from the intermediate part.

[0071] In Figs 11 to 14, an alternative folding procedure is illustrated. Depending on the weight of the counterweights, this second procedure might be more relevant as it will allow the folding step of the first pivot mechanism of the first leg to be easier. In this procedure as seen in Figs. 11 and 12, the first step is to first rotate the extension arms 11 ,12 via their pivot mechanisms 14,16 and then rotate the counterweights 20, 22 accordingly. As seen in Figs. 13 and 14, the next step is to rotate the first clamping element 2 upwards via the first pivot mechanism 33 of the first leg 32. Since the counterweights have been moved “inside” the axis of rotation of the rotation mechanism, it will be easier to rotate the first clamping element. The final step is to fold down the first clamping element, to end in the same position as seen in Fig. 9 and 10, so that the first clamping element 2 is positioned lower and in contact with the second clamping element 4.

[0072] Figures 15-17 show an alternative embodiment of a blade clamping tool 400 which is for the most part similar to the blade clamping tool shown in figures 1-14, hence the construction and function will not be described in great detail. Figure 15 shows the blade clamping tool in an unfolded position, i.e. a position where it is used to lift a blade. Figure 17 shows the blade clamping tool in a folded position which is suitable for transporting the blade clamping tool. Note that figure 17 still shows the extension arms and counterweights in their active position. Prior to transport, additional steps will be made to fold the extension arms and the counterweights. Figure 16 shows an intermediate position between the folded and unfolded positions.

[0073] As with the previous embodiments, the blade clamping tool has a first pivot mechanism 33 and a second pivot mechanism 35 which function in a similar way to the previous embodiment and allow rotation about axes A and B respectively. A first pin locking mechanism 433 and a second pin locking mechanism 435 are arranged to lock and unlock the first and second pivot mechanism respectively. The previous embodiments also had pin locking mechanisms as is clear from figures 1-14.

[0074] However, it is to be noted that the blade clamping tool of figures 15-17 is folded in a single motion where motion about the first and second pivot mechanism occurs simultaneously. This is in contrast to the previous embodiments where first a motion about a first pivot mechanism is performed and then a motion about a second pivot axis is performed.

[0075] In this embodiment, a lifting beam 402 is detachably attached to the beam of the first clamping element 2. The lifting beam extends in a direction which is perpendicular to a longitudinal axis of the first clamping element. The lifting beam provides two lifting points 404, 406. A first lifting point 404 is provided at an inner point on the beam and a second lifting point 406 is provided at an outer point on the beam. A first sling 408 and a second sling 410 are connected respectively to the first and second lifting points. A lifting wire 412 from a crane (not shown) is connected to the first and second slings. Due to the spacing of the two lifting points on the beam, a more stable lifting I lowering operation can be provided by the crane, independent of the position and weight of the counterweights. In this embodiment, and in many other potential embodiments, the first lifting point 404 will be located on an inner side of a central axis through the portion of the blade clamping tool which is located outwardly of the first pivot axis A and the second lifting point 406 will be located outside of said central axis. The central axis would be defined as a horizontal axis parallel to the axis A of rotation of the first pivot mechanism and passing through the center of gravity of the portion of the blade clamping tool which is located outwardly of the first pivot mechanism. The terms outwardly and inwardly in this case, would be defined according to the intermediate part of the blade clamping tool. Outwardly is further away from the intermediate part and inwardly is closer to the intermediate part.

[0076] It should be noted that when the blade yoke is arranged to lift different blades, the number of plates 420 in the counterweight 422 will change depending on the weight / dimensions of the blade to be lifted. When different counterweight plates are used, the centre of gravity of the portion of the blade clamping tool arranged outside the first pivot mechanism will change. Due to the extension of the lifting beam 402, and the spacing between the two lifting points, the motion of the first clamping element can be controlled in a more secure fashion via the crane than if the crane were connected to the first clamping element via a single point 302 as was the case in the previous embodiments shown in figures 1-14.

[0077] In addition to providing a faster folding / unfolding process, a further advantage of the procedure shown in figures 15-17, is that the folding of the extension arms and the folding of the counterweights can take place in the folded position where the extension arms and the counterweights are closer to the ground. This makes handling them easier than when the blade clamping tool is in its unfolded position. An additional feature, which is difficult to see in the drawings, is that when the blade clamping tool is in its folded position, a secure connection is established between the first clamping element and the second leg and / or the intermediate part of the blade clamping tool. This secure connection ensures that the first clamping element is held in position relative to the second leg / intermediate part during transportation of the blade clamping tool in the folded position. The secure connection is in the current embodiment provided by a pin locking mechanism arranged between the first clamping element and the second leg and / or the intermediate part. It is to be noted that the figures and the above description have shown the example embodiments in a simple and schematic manner. Many of the specific mechanical details have not been shown since the person skilled in the art should be familiar with these details and they would just unnecessarily complicate this description. For example, the specific materials used and the specific manufacturing procedures have not been described in detail since it is maintained that the person skilled in the art would be able to find suitable materials and suitable processes to manufacture the blade clamping tool according to the current invention.

Claims

Claims1. A blade clamping tool for a wind turbine blade, said blade clamping tool comprising: a. a first clamping element adapted to be in contact with a first surface of a wind turbine blade when the wind turbine blade is clamped in the blade clamping tool, b. a second clamping element adapted to be in contact with a second surface of the wind turbine blade when the wind turbine blade is clamped in the blade clamping tool, said second surface being opposite to said first surface, c. a c-formed bracket comprising i. a first leg connected to the first clamping element, ii. a second leg connected to the second clamping element, and iii. an intermediate part connecting the first and second leg, d. characterised in that the first leg of the c-formed bracket comprises a first pivot mechanism arranged to pivot the first clamping element away from the second clamping element and, e. in that the intermediate part comprises a second pivot mechanism arranged to pivot the first leg towards the second clamping element.

2. A blade clamping tool according to claim 1, characterized in that the first and second pivot mechanisms have a locked position where the first and second pivot mechanisms are locked and an unlocked position where the first and second pivot mechanisms are free to pivot.

3. A blade clamping tool according to claim 1 or 2, characterized in that the first and / or second pivot mechanisms have a range of motion which is at least 60 degrees.

4. A blade clamping tool according to any one of claims 1 to 3, characterized in that a pivot axis of the first pivot mechanism is placed at a first horizontal distance from the connection between the first leg and the first clampingelement and at a second horizontal distance from the connection between the first leg and the intermediate part.

5. A blade clamping tool according to claim 4, characterized in that said first and / or said second horizontal distance is greater than 0.5m.

6. A blade clamping tool according to any one of claims 1 to 5, characterized in that a pivot axis of the second pivot mechanism is placed at a first vertical distance from the connection between the first leg and the intermediate part and at a second vertical distance from the connection between the second leg and the intermediate part.

7. A blade clamping tool according to claim 6, characterized in that said first and / or said second vertical distance is greater than 0.5m.

8. A blade clamping tool according to any one of claims 1 to 7, characterized in that said blade clamping tool further comprises: a. a first extension arm extending from a first end of the first clamping element, and b. a second extension arm extending from a second end of the first clamping element.

9. A blade clamping tool according to claim 8, characterised in that the first and second extension arms are pivotally connected to the first clamping element about first and second pivot axes respectively and in that the first and second extension arms are arranged to be able to pivot between two positions, an extended position and a folded position.

10. A blade clamping tool according to any one of claims 1 to 9, characterized in that said blade clamping tool further comprises: a. a first counterweight located near a first end of the first clamping element, and b. a second counterweight located near a second end of the first clamping element.

11. A blade clamping tool according to claim 10, characterised in that the first and second counterweights are pivotally connected to the first clamping element via first and second pivot axes respectively and in that the first and second counterweights are arranged to be able to pivot between an extended position and a folded position.

12. A blade clamping tool according to claim 10 or 11, characterized in that the first counterweight and the second counterweight are arranged to extend in a horizontal direction when in their extended positions.

13. A blade clamping tool according to any one of claims 1 to 12, characterized in that the blade clamping tool further comprises a first lifting point arranged on one side of a central axis of the first clamping element and a second lifting point arranged on another side of a central axis of the first clamping element, said first and second points being spaced apart by a horizontal distance.

14. A method for folding a blade clamping tool according to any one of claims 1 to 13, said method comprising the steps of: a. rotating a portion of the first leg arranged outwardly of the first pivot mechanism, at least 60 degrees in an initial upwards direction away from the second clamping element, and b. rotating a portion of the intermediate part arranged upwardly of the second pivot mechanism at least 60 degrees in an initial outward direction towards the second clamping element.

15. A method according to claim 14, characterized in that the method further includes the step of rotating the first and second extension arms, upwards and then towards the C-shaped bracket about horizontal axes and / or in that the method further includes the step of rotating the first and second counterweight, towards the C-formed bracket about vertical axes.

16. A method according to claim 14 or 15, characterized in that the rotation about the first pivot mechanism and the rotation about the second pivot mechanism are performed at the same time, so that the first clamping element rotates outwardly due to the rotation about the first pivot mechanism and downwardly due to the rotation about the second pivot mechanism.

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