Tools, tool kits, systems and methods for gripping fasteners

Abstract

The present disclosure relates to tools (1), tool kits, systems and methods (100) for gripping a plurality of fasteners (43) and carrying the fasteners (43) to a wind turbine component (47) where they are to be inserted. The present disclosure further relates to wind turbine components (47) such as wind turbine tower sections, and to wind turbines (10). The present disclosure further relates to methods for joining two wind turbine components with fasteners (43). A tool (1) for gripping a plurality of fasteners (43) to be inserted in a plurality of through holes (51) of a wind turbine component (47) having a first pitch, the through holes (51) being arranged along an imaginary line having a first curvature, comprises: a first spreader bar (3) including a plurality of recesses (27) configured to receive the plurality of fasteners (43) and a frame (2) configured to support the first spreader bar (3). The plurality of recesses (27) is arranged along an imaginary line having the first curvature, and the recesses have the first pitch.

Description

TOOLS, TOOL KITS, SYSTEMS AND METHODS FOR GRIPPING FASTENERSTECHNICAL FIELD

[0001] The present disclosure relates to wind turbine components such as wind turbine tower sections, and to wind turbines. The present disclosure further relates to systems and methods for joining wind turbine components, such as tower sections, with fasteners. More particularly, the present disclosure relates to tools, tool kits, systems and methods for gripping a plurality of fasteners and transporting the fasteners to a wind turbine component in which they are to be inserted. The present disclosure further relates to methods for joining two wind turbine components with fasteners using such tools.BACKGROUND

[0002] Modern wind turbines are commonly used to supply electricity into the electrical grid. Wind turbines of this kind generally comprise a tower and a rotor arranged on the tower. The rotor, which typically comprises a hub and a plurality of blades, is set into rotation under the influence of the wind on the blades. Said rotation generates a torque that is normally transmitted through a rotor shaft to a generator, either directly (“directly driven” or “gearless”) or through the use of a gearbox. This way, the generator produces electricity which can be supplied to the electrical grid.

[0003] The wind turbine hub may be rotatably coupled to a front of the nacelle. The wind turbine hub may be connected to a rotor shaft, and the rotor shaft may then be rotatably mounted in the nacelle using one or more rotor shaft bearings arranged in a frame inside the nacelle. The nacelle is a housing arranged on top of a wind turbine tower that may contain and protect the gearbox (if present) and the generator (if not placed outside the nacelle) and, depending on the wind turbine, further components such as a power converter, and auxiliary systems.

[0004] The wind turbine tower is typically composed of a plurality of tower sections that are stacked on top of each other and joined to each other at tower flanges. Fasteners such as studs or “stud bolts” are usually used for joining two portions of the wind turbine. For example, studs may be used to join two tower sections or the top tower section and the nacelle. Studs may also be used to join the bottom tower section and the wind turbine foundation.

[0005] Studs may be provided in storage containers or boxes. After the boxes are carried to the installation site for the wind turbine, the boxes may be opened, and operators may transferthe studs near two flanges of the components to be joined. For example, two tower sections to be joined may be arranged such that the holes in their flanges are aligned, specifically such that the through holes of the bottom flange of the upper tower section and the through holes of the top flange of the lower tower section are aligned along the vertical direction. Operators may then manually insert the studs in the through holes of the flanges of the tower sections.

[0006] Another way may include moving the studs from the boxes near a bottom flange of an upper tower section. The upper tower section may be supported on a plurality of supports such that the bottom flange is above the floor. Operators may then insert the studs through the through holes of the flange of the upper tower section. The studs may be provided with nuts on their top portion such that the studs with the nuts are supported on the bottom flange when inserted in the through holes of the bottom flange. The tower section with the studs may then be lifted and positioned above a lower tower section. The upper tower section may be lowered onto the lower tower section such that the studs are also inserted in the through holes of the top flange of the lower tower section.

[0007] In both examples, the operators may use tools to help them grip and move the studs. In general, also in both examples, each stud is moved from the storage box to the crane or to the corresponding through hole of the flange individually. I.e., a first stud may be picked up and carried, and then a second stud may be picked and carried, and so on. This is time consuming and a heavy task for the operators.

[0008] Also, as modern wind turbines have grown increasingly more powerful and correspondingly larger, the studs required are increasingly larger and heavier. For example, wind turbines able to provide a rated power above 10 MW may have towers exceeding 130 m in height and 800 tons in weight. The diameter of tower sections may be between 5 and 10 m, or even more. And a stud, for example for joining two tower sections, may weigh 20 kg or more.

[0009] Due to their weight and size, studs may be difficult to pick from the storage box and carry. This complicates the work of the operators and may increase the risk of the operators being injured.

[0010] The present disclosure aims to improve picking of the studs from a storage box and carrying them, and to reduce the time required for inserting the studs in the through holes of the corresponding flange.SUMMARY

[0011] In an aspect of the present disclosure, a tool for gripping a plurality of fasteners to be inserted in a plurality of through holes of a wind turbine component is provided. The through holeshave a first pitch and are arranged along an imaginary line having a first curvature. The tool comprises: a first spreader bar including a plurality of recesses configured to receive the plurality of fasteners, and a frame configured to support the first spreader bar. The plurality of recesses of the first spreader bar is arranged along an imaginary line having the first curvature, and the recesses of the plurality of recesses of the first spreader bar have the first pitch.

[0012] According to this aspect, the tool comprises a spreader bar which includes a plurality of recesses. The recesses are size and shaped such that a plurality of fasteners can be picked, e.g. supported and lifted, by the tool with the spreader bar. The plurality of recesses is arranged along an imaginary curved line. Specifically, the imaginary curved line matches another imaginary curved line which joins a plurality of through holes in which the fasteners are to be inserted. For example, a wind turbine tower section may include a flange with through holes for receiving studs or other fasteners. Some of the through holes may define an imaginary curved line with a certain curvature, e.g. with a certain radius of curvature. The curvature defined by the plurality of recesses of the spreader bar may therefore match the curvature defined by the plurality of through holes of the flange of the wind turbine tower section. In addition, the pitch between the plurality of recesses and the pitch between the plurality of through holes is the same.

[0013] In this manner, when the plurality of fasteners is picked up, the fasteners are already positioned such that they may be transported together and such that, when arranged above the plurality of through holes (with the appropriate orientation), the plurality of fasteners may be lowered at once and inserted in the through holes. The matching between the curvature defined by the plurality of recesses and the curvature defined by the plurality of through holes, as well as the matching between the separation, i.e. pitch, between the recesses and the separation between the through holes, enables a fast, easy and safe way to grip fasteners and insert them in the corresponding through holes.

[0014] Within the scope of the present disclosure, different fasteners, such as bolts or studs may be used. Throughout this disclosure, a stud may be understood as a rod that is threaded on both ends and is used to join two components, for example two wind turbine tower sections, a nacelle and a top tower section or a bottom tower section and a wind turbine foundation. Herein, a stud as picked up may specifically include a pre-mounted nut at one end. When oriented vertically, a stud may comprise a top portion and a bottom portion. The nut may be arranged at the top portion. In this manner, the stud may be supported by the tool for example including a spacer element. When the stud has been inserted to the through holes of the components to be joined, another nut may be arranged at the bottom portion of the stud for joining and securing the components. In some examples, a nut may be integrally formed with a stud. In other examples, the stud may comprise the nut, but they may be separate elements.

[0015] Throughout this disclosure, a spreader bar may be understood as an elongated element, including for example one or more elongated plates, which comprises a plurality of recesses, configured to receive a plurality of fasteners with a suitable separation or pitch. The recesses are configured to arrange the fasteners in accordance with the holes in which they are to be inserted.

[0016] In another aspect, a tool kit is provided. The tool kit comprises a tool according to the previous aspect, and a plurality of spacer elements configured to be removably inserted in the plurality of recesses of the first spreader bar and configured to receive the plurality of fasteners.

[0017] The plurality of spacer elements may help to support the plurality of fasteners with respect to a flange of a wind turbine component including the through holes in which the plurality of fasteners is to be inserted, thereby facilitating separating the tool from the plurality of fasteners.

[0018] In a further aspect, another tool kit is provided. The tool kit comprises a tool according to the first aspect, and an additional spreader bar including a plurality of recesses configured to receive a plurality of fasteners. A size of the recesses, and / or a pitch between recesses, and / or a number of recesses and / or a curvature of an imaginary line joining the plurality, is different from the corresponding features of the first spreader bar.

[0019] The tool may therefore be used for installing fasteners of different sizes, e.g. different diameters, as well as for installing fasteners in wind turbine components having different pitches or separations between the fasteners, installing fasteners in different wind turbines, e.g. wind turbines having wind turbine sections of different sizes, etc. Additional spreader bar(s) confer versatility to the tool.

[0020] The above tool kits may be combined. For example, a tool kit may both comprise at least a plurality of spreader bars and at least an additional spreader bar.

[0021] In a further aspect, a system for gripping and carrying fasteners for a wind turbine is provided. The system comprises a column, an arm attached to the column and configured to horizontally move a tool as described throughout this disclosure, and a lifting device connected to the arm and carrying the tool. The lifting device is configured to vertically move the tool.

[0022] The system of this aspect may help to move a tool according to the first aspect in a controlled and safe manner.

[0023] In a further aspect, a method is provided. The method comprises arranging a tool having a spreader bar in proximity of a plurality of fasteners. The tool may be a tool as described throughout this disclosure, e.g. the tool of the first aspect. The method further comprises arranging the spreader bar such that a plurality of recesses of the spreader bar is arranged around the plurality of fasteners, and lifting the tool and thereby lifting the fasteners. The method furthercomprises placing the plurality of fasteners above a plurality of through holes of a top wind turbine component, and inserting the plurality of fasteners in the plurality of through holes. The recesses of the spreader bar have a pitch corresponding to a pitch of the through holes of the top wind turbine component and the recesses are arranged along an imaginary line having a curvature corresponding to a curvature of the through holes of the top wind turbine component.

[0024] Therefore, the plurality of fasteners may be easily and quickly arranged in their corresponding through holes.

[0025] According to a further aspect, a tool kit for gripping and carrying a plurality of fasteners for a wind turbine is provided. The tool kit comprises a tool. The tool comprises a frame and a spreader bar. The spreader bar may be configured to be detachably secured to the frame of the tool. The spreader bar includes a plurality of recesses configured to receive a plurality of spacer elements. The tool kit further comprises a plurality of spacer elements configured to be inserted in the plurality of recesses of the spreader bar and configured to receive the plurality of fasteners.

[0026] The provision of a plurality of spreader bars as described throughout this disclosure may facilitate separating the tool from the plurality of fasteners, e.g. studs, once the fasteners are partially arranged in their corresponding through holes, e.g. in the through holes of a flange of a wind turbine tower section to be mounted on top of another wind turbine tower section. Also, the spacers may help to avoid the fasteners protruding under a bottom surface of the flange of the top wind turbine component. In this manner, when the top wind turbine component is arranged above the bottom wind turbine component, collisions of the bottom portions of the fasteners with the bottom wind turbine component may be avoided. The fasteners may safely be inserted in the through holes of the bottom wind turbine component by aligning the through holes of the top and bottom wind turbine components and removing the spacer elements.

[0027] The spacer elements may be elongated and may comprise longitudinal recesses for surrounding a portion of the fasteners. The spacer elements may comprise flanges at their ends, specifically their longitudinal ends. When positioned vertically, a spacer element with a fastener arranged therein may help to support the fastener. A nut of the fastener may rest on top flange. Also, when the fastener is partially inserted in a through hole, the bottom flange may help to support the fastener with respect to the flange comprising the through hole.

[0028] Features, details and explanations of the previous aspects may be applicable to, and combined with, this aspect.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 schematically illustrates a perspective view of one example of a wind turbine;

[0030] Figure 2 illustrates an example of a hub and a nacelle of a wind turbine;

[0031] Figure 3A schematically illustrates a perspective view of an example of a tool for gripping a plurality of studs for a wind turbine without a spreader bar;

[0032] Figure 3B schematically illustrates a perspective view of the tool of figure 3A with a spreader bar being arranged in the tool frame;

[0033] Figure 4 schematically illustrates a perspective view of a system comprising the tool of figures 3A and 3B;

[0034] Figure 5 schematically illustrates a flowchart of an example of a method;

[0035] Figure 6 schematically illustrates an example of a tool with a spreader bar being approached to a plurality of studs;

[0036] Figure 7 schematically illustrates an example of a tool positioned inside a wind turbine tower section for populating the through holes of the flange of the tower section with studs;

[0037] Figure 8 schematically illustrates an example of a plurality of studs partially inserted in a plurality of through holes of a flange of a wind turbine tower section;

[0038] Figure 9 schematically illustrates an example of how a plurality of spacer elements is separated from the plurality of studs of figure 8; and

[0039] Figure 10 schematically illustrates an example of how the plurality of studs of figure 9 has advanced downwards after removing the plurality of spacer elements.DETAILED DESCRIPTION OF EXAMPLES

[0040] Reference now will be made in detail to embodiments of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the disclosure, not as a limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the teaching. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0041] Figure 1 is a perspective view of an example of a wind turbine 10. In the example, the wind turbine 10 is a horizontal-axis wind turbine. Alternatively, the wind turbine 10 may be a vertical-axis wind turbine. In the example, the wind turbine 10 includes a tower 15 that extends from a support system 14 on a ground 12, a nacelle 16 mounted on tower 15, and a rotor 18 that is coupled to nacelle 16. The rotor 18 includes a rotatable hub 20 and at least one rotor blade 22coupled to and extending outward from the hub 20. In the example, the rotor 18 has three rotor blades 22. In an alternative embodiment, the rotor 18 includes more or less than three rotor blades 22. The tower 15 may be fabricated from tubular steel to define a cavity (not shown in figure 1) between a support system 14 and the nacelle 16. In an alternative embodiment, the tower 15 is any suitable type of a tower having any suitable height. According to an alternative, the tower can be a hybrid tower comprising a portion made of concrete and a tubular steel portion. Also, the tower can be a partial or full lattice tower. A wind turbine 10 may be placed both onshore and offshore.

[0042] The rotor blades 22 are spaced about the hub 20 to facilitate rotating the rotor 18 to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. The rotor blades 22 are mated to the hub 20 by coupling a blade root portion to the hub 20 at a plurality of load transfer regions 26. The load transfer regions 26 may have a hub load transfer region and a blade load transfer region (both not shown in figure 1). Loads induced to the rotor blades 22 are transferred to the hub 20 via the load transfer regions 26.

[0043] In examples, the rotor blades 22 may have a length ranging from about 15 meters (m) to about 90 m or more. Rotor blades 22 may have any suitable length that enables the wind turbine 10 to function as described herein. For example, non-limiting examples of blade lengths include 20 m or less, 37 m, 48.7 m, 50.2m, 52.2 m or a length that is greater than 91 m. As wind strikes the rotor blades 22 from a wind direction 28, the rotor 18 is rotated about a rotor axis 30. As the rotor blades 22 are rotated and subjected to centrifugal forces, the rotor blades 22 are also subjected to various forces and moments. As such, the rotor blades 22 may deflect and / or rotate from a neutral, or non-deflected, position to a deflected position.

[0044] Moreover, a pitch angle of the rotor blades 22, i.e., an angle that determines an orientation of the rotor blades 22 with respect to the wind direction, may be changed by a pitch system 32 to control the load and power generated by the wind turbine 10 by adjusting an angular position of at least one rotor blade 22 relative to wind vectors. Pitch axes 34 of rotor blades 22 are shown. During operation of the wind turbine 10, the pitch system 32 may particularly change a pitch angle of the rotor blades 22 such that the angle of attack of (portions of) the rotor blades are reduced, which facilitates reducing a rotational speed and / or facilitates a stall of the rotor 18.

[0045] In the example, a blade pitch of each rotor blade 22 is controlled individually by a wind turbine controller 36 or by a pitch control system 80. Alternatively, the blade pitch for all rotor blades 22 may be controlled simultaneously by said control systems.

[0046] Further, in the example, as the wind direction 28 changes, a yaw direction of the nacelle 16 may be rotated about a yaw axis 38 to position the rotor blades 22 with respect to wind direction 28.

[0047] In the example, the wind turbine controller 36 is shown as being centralized within the nacelle 16, however, the wind turbine controller 36 may be a distributed system throughout the wind turbine 10, on the support system 14, within a wind farm, and / or at a remote-control center. The wind turbine controller 36 includes a processor 40. Further, many of the other components described herein include a processor.

[0048] As used herein, the term “processor” is not limited to integrated circuits referred to in the art as a computer, but broadly refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific, integrated circuit, and other programmable circuits, and these terms are used interchangeably herein. It should be understood that a processor and / or a control system can also include memory, input channels, and / or output channels.

[0049] Figure 2 is an enlarged sectional view of a portion of the wind turbine 10. In the example, the wind turbine 10 includes the nacelle 16 and the rotor 18 that is rotatably coupled to the nacelle 16. More specifically, the hub 20 of the rotor 18 is rotatably coupled to an electric generator 42 positioned within the nacelle 16 by the main shaft 44, a gearbox 46, a high-speed shaft 48, and a coupling 50. In the example, the main shaft 44 is disposed at least partially coaxial to a longitudinal axis (not shown) of the nacelle 16. A rotation of the main shaft 44 drives the gearbox 46 that subsequently drives the high-speed shaft 48 by translating the relatively slow rotational movement of the rotor 18 and of the main shaft 44 into a relatively fast rotational movement of the high-speed shaft 48. The latter is connected to the generator 42 for generating electrical energy with the help of a coupling 50. Furthermore, a transformer 90 and / or suitable electronics, switches, and / or inverters may be arranged in the nacelle 16 in order to transform electrical energy generated by the generator 42 having a voltage between e.g. 400V to 1000 V into electrical energy having medium voltage (10 - 35 KV). Offshore wind turbines may have for example generator voltages between 650 V and 3500 V, and transformer voltages may for instance be between 30 kV and 70 kV. Said electrical energy is conducted via power cables from the nacelle 16 into the tower 15.

[0050] The gearbox 46, generator 42 and transformer 90 may be supported by a main support structure frame of the nacelle 16, optionally embodied as a main frame 52. The gearbox 46 may include a gearbox housing that is connected to the main frame 52 by one or more torque arms 103. In the example, the nacelle 16 also includes a main forward support bearing 60 and a main aft support bearing 62. Furthermore, the generator 42 can be mounted to the main frame 52 bydecoupling support means 54, in particular in order to prevent vibrations of the generator 42 to be introduced into the main frame 52 and thereby causing a noise emission source.

[0051] Optionally, the main frame 52 is configured to carry the entire load caused by the weight of the rotor 18 and components of the nacelle 16 and by the wind and rotational loads, and furthermore, to introduce these loads into the tower 15 of the wind turbine 10. The rotor shaft 44, generator 42, gearbox 46, high-speed shaft 48, coupling 50, and any associated fastening, support, and / or securing device including, but not limited to, support 52, and forward support bearing 60 and aft support bearing 62, are sometimes referred to as a drive train 64.

[0052] In some examples, the wind turbine may be a direct drive wind turbine without gearbox 46. Generator 42 operate at the same rotational speed as the rotor 18 in direct drive wind turbines. They therefore generally have a much larger diameter than generators used in wind turbines having a gearbox 46 for providing a similar amount of power than a wind turbine with a gearbox.

[0053] The nacelle 16 also may include a yaw drive mechanism 56 that may be used to rotate the nacelle 16 and thereby also the rotor 18 about the yaw axis 38 to control the perspective of the rotor blades 22 with respect to the wind direction 28.

[0054] For positioning the nacelle 16 appropriately with respect to the wind direction 28, the nacelle 16 may also include at least one meteorological measurement system which may include a wind vane and anemometer. The meteorological measurement system 58 can provide information to the wind turbine controller 36 that may include wind direction 28 and / or wind speed. In the example, the pitch system 32 is at least partially arranged as a pitch assembly 66 in the hub 20. The pitch assembly 66 includes one or more pitch drive systems 68 and at least one sensor 70. Each pitch drive system 68 is coupled to a respective rotor blade 22 (shown in figure 1) for modulating the pitch angel of a rotor blade 22 along the pitch axis 34. Only one of three pitch drive systems 68 is shown in figure 2.

[0055] In the example, the pitch assembly 66 includes at least one pitch bearing 72 coupled to hub 20 and to a respective rotor blade 22 (shown in figure 1) for rotating the respective rotor blade 22 about the pitch axis 34. The pitch drive system 68 includes a pitch drive motor 74, a pitch drive gearbox 76, and a pitch drive pinion 78. The pitch drive motor 74 is coupled to the pitch drive gearbox 76 such that the pitch drive motor 74 imparts mechanical force to the pitch drive gearbox 76. The pitch drive gearbox 76 is coupled to the pitch drive pinion 78 such that the pitch drive pinion 78 is rotated by the pitch drive gearbox 76. The pitch bearing 72 is coupled to pitch drive pinion 78 such that the rotation of the pitch drive pinion 78 causes a rotation of the pitch bearing 72.

[0056] Pitch drive system 68 is coupled to the wind turbine controller 36 for adjusting the pitch angle of a rotor blade 22 upon receipt of one or more signals from the wind turbine controller 36.In the example, the pitch drive motor 74 is any suitable motor driven by electrical power and / or a hydraulic system that enables pitch assembly 66 to function as described herein. Alternatively, the pitch assembly 66 may include any suitable structure, configuration, arrangement, and / or components such as, but not limited to, hydraulic cylinders, springs, and / or servomechanisms. In certain embodiments, the pitch drive motor 74 is driven by energy extracted from a rotational inertia of hub 20 and / or a stored energy source (not shown) that supplies energy to components of the wind turbine 10.

[0057] The pitch assembly 66 may also include one or more pitch control systems 80 for controlling the pitch drive system 68 according to control signals from the wind turbine controller 36, in case of specific prioritized situations and / or during rotor 18 overspeed. In the example, the pitch assembly 66 includes at least one pitch control system 80 communicatively coupled to a respective pitch drive system 68 for controlling pitch drive system 68 independently from the wind turbine controller 36. In the example, the pitch control system 80 is coupled to the pitch drive system 68 and to a sensor 70. During normal operation of the wind turbine 10, the wind turbine controller 36 may control the pitch drive system 68 to adjust a pitch angle of rotor blades 22.

[0058] According to an embodiment, a power generator 84, for example comprising a battery and electric capacitors, is arranged at or within the hub 20 and is coupled to the sensor 70, the pitch control system 80, and to the pitch drive system 68 to provide a source of power to these components. In the example, the power generator 84 provides a continuing source of power to the pitch assembly 66 during operation of the wind turbine 10. In an alternative embodiment, power generator 84 provides power to the pitch assembly 66 only during an electrical power loss event of the wind turbine 10. The electrical power loss event may include power grid loss or dip, malfunctioning of an electrical system of the wind turbine 10, and / or failure of the wind turbine controller 36. During the electrical power loss event, the power generator 84 operates to provide electrical power to the pitch assembly 66 such that pitch assembly 66 can operate during the electrical power loss event.

[0059] In the example, the pitch drive system 68, the sensor 70, the pitch control system 80, cables, and the power generator 84 are each positioned in a cavity 86 defined by an inner surface 88 of hub 20. In an alternative embodiment, said components are positioned with respect to an outer surface of hub 20 and may be coupled, directly or indirectly, to the outer surface.

[0060] In an aspect of the disclosure, a tool for gripping a plurality of fasteners, e.g. studs, to be inserted in a plurality of through holes of a wind turbine component, the plurality of through holes having a first pitch first and arranged along an imaginary line having a first curvature is provided. The tool comprises a first spreader bar including a plurality of recesses configured to receive the plurality of fasteners and a frame configured to support the first spreader bar. Theplurality of recesses of the first spreader bar is arranged along an imaginary line having the first curvature, and the recesses of the plurality of recesses of the first spreader bar have the first pitch.

[0061] The plurality of recesses of the spreader bar is specifically arranged along an imaginary curve following an imaginary curve followed by the through holes of a region in which the plurality of fasteners is to be inserted. For example, as the tower sections may be cylindrical or conical, the through holes of the flanges of two tower sections to be joined may form a circle. This circle has a certain radius of curvature. The recesses of the spreader bar follow an imaginary curve which overlaps a portion of the aforementioned circle. I.e., the imaginary curved line followed by the recesses has a same radius of curvature as the radius of curvature of the circle.

[0062] The pitch between the plurality of through holes is also the same as the pitch between the recesses of the spreader bar. This pitch or separation may be measured along a tangential, e.g. circumferential, direction of the imaginary line joining the recesses of the spreader bar and of the imaginary line joining the through holes. A pitch or separation may be measured between the centers of two consecutive recesses or through holes, specifically along the imaginary curve along which the recesses and the through holes are arranged. Therefore, when the fasteners are arranged in the recesses of the spreader bar, they may be lifted above the through holes into which they will be inserted such that lowering the fasteners directly introduces the fasteners into the through holes due to the spreader bar and the flange of the wind turbine component including the through holes having a same radius of curvature and a same pitch or separation between the recesses and between the holes. “Pitch” and “separation” are used interchangeably herein.

[0063] The imaginary line joining the plurality of recesses of the first spreader bar may protrude outwards. As the tool may be operated from within a wind turbine component, e.g. a tower section, a front of the first spreader bar which is to face the fasteners to be gripped may protrude outwards for easily overlapping the imaginary curved lines linked to the first spreader bar and the plurality of through holes when lifting the fasteners and arranging them above the through holes into which they will be inserted.

[0064] Figure 3A schematically illustrates a perspective view of an example of a tool 1 for gripping a plurality of studs for a wind turbine 10 without a spreader bar. Figure 3B schematically illustrates a perspective view of the tool 1 of figure 3A with a spreader bar 3 arranged in the tool frame. The tool 1 may extend along a longitudinal direction “x” and have a length along this direction. The tool 1 may extend along a bottom to top direction “z” and have a height along this direction. The tool 1 may extend along a front to back direction “y” and have a width or depth along this direction. When the tool is lifted for gripping the studs and transporting them to the holes in which they will be inserted, the longitudinal direction “x” may correspond to a horizontaldirection, the “z” direction may correspond to a vertical direction and the “y” direction may correspond to a horizontal direction. The “x”, “y” and “z” directions are perpendicular to each other, see figure 3A.

[0065] The tool 1 comprises a frame 2 configured to support the first spreader bar 3. The first spreader bar 3 may be removably attached to the frame 2. In some examples, the tool 1 may be configured to receive the spreader bar 3. The frame 2 may comprise flanges, for example at longitudinal ends of the frame, for supporting the first spreader bar. The flanges may be integrally formed with other portions of the frame in some examples. In other examples, elements including the flanges may be attached to other portions of the frame.

[0066] The frame 2 may for example comprise a base 4, see figure 3A. The base 4 may have a central portion 5 and two longitudinal end portions 6, 7. A distance between the longitudinal ends of the two longitudinal end portions 6, 7 may define a length of the tool 1 along the “x” direction. The longitudinal end portions 6, 7 may comprise the flanges 8, 9 for supporting the first spreader bar 3. For example, a bottom portion of the tool 1 may resemble a C- or II- shape, the flanges 8, 9 being the end portions of the “C” or the “II”.

[0067] A flange 8, 9 may comprise a surface 11 for supporting the first spreader bar 3. The surface 11 may extend along the “x” and “y” directions. The supporting surface 11 may be provided as a top surface of a plate. The flange 8, 9, e.g. the plate, may comprise a portion of a locking mechanism for securing the first spreader bar 3 to the frame 2 of the tool 1.

[0068] One example of a locking mechanism is illustrated in figures 3A and 3B: the flanges 8, 9 may comprise a pin 13, see figure 3B. The pin 13 may be rod shaped. The pin 13 may be at least partially threaded. The locking mechanism may further comprise a lock nut 17 for engaging the pin 13.

[0069] In order to position the spreader bar with respect to the frame, in this example, the longitudinal end portions of the spreader bar 3 comprise through holes through which the pins 13 can be inserted and the spreader bar can rest on the flanges 8, 9, specifically on the supporting surface 11 of the flanges 8, 9. Lock nuts 17 may then be arranged on the pins 13 for mechanically retaining and securing the spreader bar 3 to the tool frame 2.

[0070] Other suitable locking mechanisms may be provided in this or in other examples. For example, the longitudinal end portions of the first spreader bar 3 may comprise pins, and the flanges 8, 9 of the tool 1 may comprise through holes in which the pins may be inserted. A lock nut 17, a nut or a suitable element may be used to secure the spreader bar 3 to the tool frame. Or both the flanges 8, 9 and the end longitudinal portions of the first spreader bar 3 may comprise through holes, and bolts and nuts may for example be used to detachably secure the spreader bar 3 to the tool frame. Still in other examples, other fasteners may be provided. For example,clamps or magnets may be used. In general, any suitable lock mechanism or fastener enabling a detachably attachment between the spreader bar and the tool frame may be provided.

[0071] In yet other examples, the spreader bar may be integrally formed or welded with the tool frame. A locking mechanism may be dispensed with in such examples.

[0072] The flanges 8, 9 may comprise a recess or open-ended slit 19 for receiving the first spreader bar 3, see figures 3A and 3B. The recesses 19 may be provided towards a back of the flanges 8, 9, i.e. away from the free ends of the flanges 8, 9. If a spreader bar 3 comprises a L- shaped cross-section, see e.g. figure 3B, the portion of the spreader bar which is inserted through the recesses 19 may help to balance the weight of the supported studs along the “y” direction. In other examples, through holes instead of recesses may be provided.

[0073] In further examples, the frame 2 may comprise further flanges, brackets or protrusions (protruding in the “y” direction towards the front of the tool 1 , like supporting flanges 8 and 9) for supporting the first spreader bar 3. The additional flanges, brackets or protrusions may comprise one or more features of the features described with respect to flanges 8 and 9. For example, additional flanges may lack or may include a locking mechanism and / or one or more recesses or through holes.

[0074] The tool 1 , e.g. the tool frame, may further comprise a handle 21 for manipulating the tool 1 , see figure 6. The handle 21 may be provided at the back of the frame 2, specifically opposite the supporting flanges 8, 9. The handle 21 may protrude from the central portion 5 of the tool 1. The handle 21 may be used to approach the tool 1 , in particular the spreader bar 3 mounted on the tool 1 , to the studs that are to be picked up in a controlled and precise manner. The handle may be integrally formed with the frame 2 in some examples.

[0075] The tool 1 may further comprise a cover plate 23, see e.g. figures 3A and 3B, rotatably connected to the frame 2 for limiting a movement of the studs when transporting the studs to the plurality of through holes of the wind turbine component. The cover plate 23 may be rotatably or hingedly connected to the frame 2, e.g. to a central portion 5 of the frame 2.

[0076] The cover plate 23 may help to push the top portions of the studs downwards after they have been arranged in the recesses of the first spreader bar 3. As explained further below, the cover plate 23 may be vertically positioned (or positioned with a relatively small inclination with respect to the vertical direction, see e.g. figure 3B) when the plurality of studs is arranged in the spreader bar 3. Once the plurality of studs is arranged in the spreader bar 3, the cover plate 23 may be lowered to a horizontal position (see e.g. figure 3A). Therefore, all the studs may be properly supported by the spreader bar. For example all the studs may protrude upwards from the spreader bar 3 by the same amount. The cover plate 23 may also help to protect the studs while carrying them. The cover plate 23 may also help to prevent or reduce a movement of thestuds along the “y” direction, i.e. along the front-back direction of the tool 1. The cover plate 23 may comprise a front flange 24 to this end.

[0077] The tool 1 may comprise more than one cover plate. For example, the tool 1 of the example of figures 3A and 3B comprises two cover plates. The two cover plates of this example move jointly.

[0078] The extension of a set of cover plates 23 arranged in the tool 1 may have similar dimensions to the dimensions of the first spreader bar. For example, a length of the set of the cover plates (measured along the “x” direction) and a length of the first spreader bar 3 may be similar, and a width of the cover plates (measured along the “y” direction) and a width of the spreader bar may be similar. This may also be applicable to a single cover plate 23 if the tool 1 is provided with a single cover plate.

[0079] The frame 2 may be configured to be removably connected to a lifting device. The frame may be provided with a shackle 25, for example in a top portion of the frame, see figures 3A and 3B, or with any suitable element to which the lifting device may be connected.

[0080] Figure 3B shows an example of a first spreader bar 3. The first spreader bar 3 comprises a plurality of recesses 27. The recesses 27 are specifically provided at a front portion of the spreader bar 3. A front of the first spreader bar 3 may thus be configured to face a container or storage box comprising a plurality of studs to be gripped and to partially surround the studs due to the presence of the recesses 27.

[0081] The plurality of recesses 27 may follow a curved imaginary line. The curved imaginary line may define a radius of curvature for the plurality of the recesses 27. The dimensions and shape of the recesses, as well as a space between the recesses, may be adapted to the studs to be handled and transported, to the through holes in which they are to be inserted and the curvature (and thus the radius of curvature) of these through holes. I.e., a radius of curvature of the plurality of recesses 27 of the first spreader bar 3 matches a radius of curvature of the through holes in which the studs are to be inserted.

[0082] A length of the first spreader bar 3 may be sufficiently large such that the tool frame may suitably support the spreader bar 3. For example, a length of the first spreader bar 3 and a length of the frame 2 of the tool 1 may be similar. Likewise, an average width of the first spreader bar 3 may be similar to a length of the flanges 8, 9 of the tool 1 in some examples.

[0083] A dimension of the recesses 27 along the longitudinal direction of the first spreader bar 3 may be different, and specifically shorter, than a dimension of the recesses along the perpendicular direction (this direction would correspond to the “y” direction of the tool 1 when the spreader bar is secured to the tool frame). This may leave space for adding a retaining element, specifically an elongated retaining element for closing the recesses 27 of the first spreader bar.

[0084] The tool 1 may further comprise a retaining element for closing the plurality of recesses 27 of the first spreader bar 3 which is removably attachable to the first spreader bar. This may help to keep the studs in place while they are lifted to their corresponding through holes. The retaining element may prevent or reduce a risk of the studs falling from the tool 1.

[0085] The portions of the first spreader bar 3 between the recesses 27 may comprise upwardly extending tabs 29, see figure 3B. The fasteners and / or spacers may be arranged behind the tabs 29.

[0086] The first spreader bar 3 may comprise a first plate portion 31 comprising the plurality of recesses 27, see figure 3B. The spreader bar may further comprise a second plate portion 33 extending from the back of the first plate portion 31. 1.e., the second plate portion 33 extends from the side opposite to the side including the plurality of recesses 27. The first plate portion 31 and the second plate portion 33 may be perpendicular to each other (or have an angle close to 90° between them). These plate portions 31 , 33 may be integrally formed. As mentioned before, the second plate portion 33 may in some examples be inserted into the recesses 19 of the flanges 8, 9 of the tool 1 and may help to provide a counterweight for the studs.

[0087] In some examples, a plurality of spacer elements 35 may further be provided, see figure 6. The spacer elements 35 may comprise, e.g. be made of, plastic in some examples. The tool 1 and the spacer elements 35 may form a tool kit. I.e., in a further aspect of the disclosure, a tool kit may be provided. The tool kit comprises a tool 1 as described throughout this disclosure, e.g. with respect to figures 3A and 3B, and further comprises a plurality of spacer elements configured to be removably inserted in the plurality of recesses 27 of the first spreader bar 3 and configured to receive the plurality of studs.

[0088] A spacer element 35 may have a tube-like shape with a longitudinal recess for being able to partially surround a stud. A spacer element 35 may comprise a first flange 37 at a longitudinal end and a second flange 39 at the opposite longitudinal end. When the spacer element 35 is arranged in a recess 27 of the first spreader bar 3, a longitudinal direction of the spacer element may be parallel to a vertical direction. The first flange may be a top flange 37 and the second flange may be a bottom flange 39. When the tool 1 with the spreader bar 3 and the spacer elements 35 grip a plurality of studs, the nuts of the studs, specifically a bottom surface thereof, may rest on the top flange 37 of the spacer elements 35. The first flange 37 may therefore be configured to support a top portion of a stud, specifically a nut thereof. If spacer elements 35 are not provided, the nuts of the studs may rest on a top surface of the first spreader bar 3, e.g. on a top surface of the first plate portion 31.

[0089] The bottom flange 39 of the spacer elements 35 may help to place the top end of the studs at a certain height above the through holes into which they are already partially inserted,see further below. The studs may not protrude below the through holes due to the presence of the spacer elements 35. As the studs may weigh e.g. over 20 kg, it may be difficult to separate the frame 2 of the tool 1 from the studs for completely inserting the studs in their corresponding through holes. The spacer elements 35 may help to support the studs and therefore, the tool may be separated from the spacer elements 35 and the studs. Then, the spacer elements 35 may be removed, and the studs may be completely inserted into the through holes. The bottom flanges may therefore be configured to support the studs with respect to a flange of a (top) wind turbine component when the studs are partially inserted into the through holes of the flange of the wind turbine component.

[0090] The spacer elements 35 may comprise a mount 41 , specifically at a back thereof, see figure 6. A mount 41 may protrude outwards and may for example protrude away from a direction faced by the recess of the spacer element 35.

[0091] The tool kit may comprise more than one plurality of spacer elements, for example two, three or more sets of spacer elements, wherein each set comprises a plurality of spacer elements. Each set of spacer elements may comprise spacer elements having a length and / or size (e.g. an internal size such as a diameter) different from a length and / or size of the spacer elements of another set. Depending on the features of the through holes (e.g. length and diameter) in which the studs are to be inserted, an appropriate set of spacer elements may be selected.

[0092] In examples where the first spreader bar 3 is removably attached to the tool frame 2, one or more additional spreader bars may be provided and used instead of the first spreader bar. The tool with the additional spreader bars may form a tool kit. A tool kit may comprise both a plurality of spacer elements 35 and one or more additional spreader bars.

[0093] In a further aspect of the disclosure, another tool kit may be provided. The tool kit comprises a tool 1 as described throughout this disclosure, e.g. with respect to figures 3A and 3B, and an additional spreader bar including a plurality of recesses configured to receive a plurality of fasteners, e.g. studs. A size of the recesses, and / or a pitch between recesses, and / or a number of recesses and / or a curvature of an imaginary line joining the plurality of recesses of the additional spreader bar, is different from the corresponding features of the first spreader bar.

[0094] For example, the plurality of recesses of the additional spreader bar may be arranged along a curved line following an imaginary line joining a plurality of through holes in which a plurality of studs is to be inserted. But the radius of curvature associated to the first spreader bar and to the additional spreader bar may be different because the studs are to be arranged in different wind turbine components whose through holes for an imaginary line with a different radius of curvature.

[0095] The previous details and explanations with respect to the first spreader bar 3 may likewise be applicable to the one or more additional spreader bars. If more than one spreader bar is provided, the spreader bars may differ for example in the dimensions of the recesses, e.g. a radius, or a length and / or width of the recesses. I.e., a size of the recesses of at least two spreader bars may be different. For example, a spreader bar may have bigger recesses, e.g. for receiving studs for joining two tower sections, whereas another spreader bar may have smaller recesses, e.g. for receiving studs for joining the nacelle and a top section of the tower. Recesses of different sizes may not only allow to grip and transport studs suitable for different portions of the wind turbine, but also it may allow to use the same tool frame 2 for installing studs in wind turbines which may have through holes for studs of different sizes.

[0096] Similarly, a pitch between the recesses, i.e. a distance between two adjacent recesses (the pitch between any two adjacent recesses of a spreader bar will usually be the same since the through holes in which the studs will be inserted are generally equally spaced along the corresponding flange), may additionally or alternatively vary between at least two spreader bars. In this manner, the same tool frame may be used for populating the through holes of a flange of different regions of a same wind turbine and / or the same tool 1 may be used for different wind turbines.

[0097] A number of recesses may also vary between at least two spreader bars of the kit.

[0098] In a further aspect of the disclosure, a system for gripping and carrying fasteners, e.g. studs, for a wind turbine is provided. Figure 4 schematically illustrates a perspective view of a system 61 comprising the tool of figures 3A and 3B. The system 61 comprises a column or post 55, and an arm 57 attached to the column 55 configured to horizontally move a tool 1 as described throughout this disclosure. The arm 57 may be flexible in some examples. The arm is flexible in the example of figure 4. A flexible arm may enable to move the tool 1 along a horizontal plane. In other examples, the arm may be telescopic and may be rotatably connected to the column 55 such that the telescopic arm may rotate around the column.

[0099] The system 61 further comprises a lifting device 49 connected to the arm 57 and carrying the tool 1. The lifting device 49 is configured to vertically moving the tool 1 , i.e. up and down. The lifting device 49 may be a hoist or winch device.

[0100] An end of the arm 57 may be connected to the column 55, e.g. to a top portion of the column. The opposite end of the arm 57 may be connected to a lifting device 49. The tool 1 may be connected, e.g. removably attached, to the lifting device 49. The lifting device 49 may therefore move the tool 1 up and down, and the arm 57 may move the tool horizontally, e.g. forward and backwards. The column 55 supports the arm 57, the lifting device 49 and the tool 1.

[0101] The column 55 may be provided on a pedestal 59. The pedestal 59 and the column 55 may be integrally formed in some examples.

[0102] System 61 may further include one or more additional spreader bars and / or one or more pluralities of spreader elements.

[0103] In a further aspect of the disclosure, a method 100 is provided. A flowchart of the method is shown in figure 5. The method comprises, at block 110, arranging a tool having a spreader bar in proximity of a plurality of fasteners. For example, arranging may comprise approaching a tool 1 with a spreader bar 3 including a plurality of recesses 27 to a plurality of studs. The recesses of the plurality of recesses may be separated by a first distance, and an imaginary line joining the plurality of recesses may have a first curvature. A separation between the studs may be the first distance, and an imaginary line joining the plurality of studs may have the first curvature.

[0104] Figure 6 schematically illustrates an example of this step of the method. The system 61 of figure 4 is used. System 61 comprises the tool 1 of the examples of figures 3A and 3B with the first spreader bar 3 of figure 3A. In this example, the wind turbine components to be joined are tower sections. A wind turbine tower may be divided into sections for enabling their transport by available vehicles and tools, and also for respecting dimensions and weight limits that a country or region may impose. A tower section may have a diameter between 5 and 10 m, may weigh over 300 tons, and may have a length of 20 meters, 30 meters, 40 meters or more. A portion of the top tower section 47 including through holes for receiving studs can be seen in figure 6. Herein, top refers to the fact that this tower section will be on top of another tower section, the bottom tower section, not necessarily that this section is the top tower section of the wind turbine tower. Similarly, the bottom refers to the fact that the bottom tower section will be below the top tower section.

[0105] Figure 7 schematically illustrates an example of system 61 and a tool 1 as described throughout this disclosure positioned inside a wind turbine tower section 47 for populating the through holes 51 of the flange of the tower section 47 with studs 43. In this example, a platform 53 is provided. The system 61 is arranged on the platform 53.

[0106] Studs may be provided in storage containers or boxes. For example, a plurality of storage containers may be provided on the platform 53. A storage box may for example comprise a base, e.g. a bottom tray, including holes in which the studs are vertically arranged, see figures 6 and 7. The studs may be arranged in rows. A row may comprise the plurality of studs to be gripped. For example, a row may comprise a number of studs which is equal to a number of the recesses 27 of the first spreader bar 3. An imaginary line 45 joining the studs of a row is indicated by a dashed line in figure 6.

[0107] In some examples, the storage box may include a plurality of parallel and straight rows of studs or other fasteners. In other examples, a storage box may include a plurality of parallel rows of studs or other fasteners, in which the rows are curved. In particular, the curvature of the rows corresponds to the curvature of the imaginary line along which the holes are arranged on the wind turbine component, particularly wind turbine tower flanges.

[0108] The system 61 for gripping and carrying studs may be provided on the platform 53. Once the system 61 and the storage boxes with the studs have been arranged on the platform, a top wind turbine component, specifically a top tower section 47 in this example, may be lifted and positioned around the platform 53. The tower section 47 may be arranged on one or more supports 63. The top tower section 47 may be lifted by a crane.

[0109] The tool 1 hangs from the lifting device 49. The lifting device 49 and the arm 57 may move the tool 1 to hold it at a suitable height from the platform 53, such that the plurality of recesses of the first spreader bar 3 faces the plurality of studs 43 to be gripped, see figure 6. One or more operators may move the tool 1 close to the studs and orient it appropriately. When the tool 1 is close to the studs, one or more operators may use the handle 21 of the tool 1 to move the tool 1 in a controlled and precise manner. The cover plates 23 of the tool 1 are in a lifted position, see figure 6.

[0110] The method further comprises, at block 120, arranging the spreader bar 3 such that a plurality of recesses of the spreader bar 3 is arranged around the plurality of fasteners. For example, a plurality of studs may be surrounded with the tool 1. The operators may move the tool, e.g. by using the handle 21 , to do this. The fasteners may be gripped. Gripping may comprise lifting the tool 1 in some examples. Lifting may cause the nuts 65, specifically the nuts arranged on a top portion of the studs, to rest on the spreader bar 3 as the studs 43 may have moved downwards due to gravity.

[0111] The cover plates 23 may be moved downward and a retainer element may be used to close the recesses 27 of the spreader bar 3 for securing the studs. Depending on the implementation, cover plate(s) and / or a retainer element may be used. For example, if spacer elements are used, see below, a retainer element may be dispensed with in some of these examples.

[0112] The method further comprises, at blocks 130 and 140, lifting the tool and thereby lifting the fasteners, and placing the plurality of fasteners above a plurality of through holes of a top wind turbine component. For example, the method may comprise lifting the tool 1 and placing the plurality of studs above a plurality of through holes of a top wind turbine component. For example, in the example of figure 7, the tool 1 (with the studs) may be vertically and horizontally moved bythe lifting device 49 and the flexible arm 57 for arranging the gripped studs over the through holes 51 of the top tower section 47.

[0113] The method further comprises, at block 150, inserting the plurality of fasteners, e.g. studs, in the plurality of through holes. The recesses of the spreader bar have a pitch corresponding to a pitch of the through holes of the top wind turbine component, and the recesses are arranged along an imaginary line having a curvature corresponding to a curvature of the through holes of the wind turbine component.

[0114] When the fasteners, e.g. studs, gripped and carried by the tool 1 are above the through holes in which they are to be inserted and suitably oriented, i.e. such that each stud 43 enters the corresponding through hole when descending the tool 1 , the tool 1 may be lowered and the studs 43 will descend through the holes. Once the studs 43 are partially inserted into the through holes, the tool 1 may be separated from the studs 43. The studs 43 may therefore be further inserted in the through holes. For example, the tool 1 may be horizontally moved such that contact is lost between the studs 43 and the tool 1. The studs 43 may go further downwards due to the action of gravity.

[0115] In some examples, the method may further comprise arranging a plurality of spacer elements 35 in the plurality of recesses of the spreader bar 3 before arranging 120 the spreader bar, see e.g. fig. 6. Spacer elements 35 as described throughout this disclosure may be used for suitably gripping the studs 43 and to help to separate the tool 1 and the studs 43.

[0116] In such examples, the block of inserting 150 may comprise partially inserting the plurality of studs in the plurality of through holes 51 and resting the spacer elements 35 on a flange including the plurality of through holes. The plurality of studs may be prevented from protruding below the through holes 51.

[0117] Figure 8 schematically illustrates an example of a plurality of studs partially inserted in a plurality of through holes of a flange of a wind turbine tower section. The example of figure 8 includes spacer elements 35, but these elements 35 may be dispensed with in other examples. When spacer elements 35 are used, the plurality of studs may descend into the through holes until the bottom flanges of the spacer elements 35 touch the top surface of the tower section flange, see figure 8. At this moment, the studs cannot continue to descend due to the presence of the spacer elements 35. The nuts 65 rest on the top flanges of the spacer elements.

[0118] As spacer elements 35 are present and they help to support the weight of the studs 43 because they contact the top surface of the flange of the top tower section, the tool 1 may be easily separated from the spacer elements 35 and the studs 43. The studs remain partially inserted in the through holes 51 , see figures 8 and 9. Removing the spacer elements 35, specifically after the through holes of a top and a bottom wind turbine component have beenaligned, see below, may cause the studs to descend further into the through holes of the top component due to the action of gravity as well as to go through the through holes of the bottom wind turbine component. In some examples, the spacer elements 35 may be removed before positioning the top wind turbine component on the bottom wind turbine component.

[0119] In the examples where the spacer elements 35 are removed before lifting and positioning the top wind turbine component on the bottom wind turbine component, the spacer elements may help to separate the tool from the spacer elements and the fasteners. In the examples where the spacer elements 35 are removed after lifting and positioning the top wind turbine component on the bottom wind turbine component, the spacer elements 35 may further help to avoid collisions of a bottom portion of the fasteners with the bottom wind turbine component, thereby protecting the fasteners.

[0120] Figure 9 schematically illustrates an example of how the plurality of spacer elements 35 are separated from the plurality of studs. Figure 10 schematically illustrates an example of how the plurality of studs has advanced downwards after removing the plurality of spacer elements 35. The studs are now supported on the flange by the nuts 65.

[0121] The mounts 41 of the spacer elements 35, see figure 6, may be used for removing the spacer elements 35. A cord, rope or similar element 67 may be passed through the handles at the back of the spacer elements 35 (or in general connected, e.g. removably attached, to the spacer elements). When the tool 1 has been separated from the spacer elements 35, the cord may be pulled for removing the spacer elements 35. As shown in the example of figure 9, more than one cord 67 may be used. This may be an efficient manner to separate the spacer elements 35 from the plurality of studs. In other examples, the spacer elements 35 may be removed in other ways. For example, each spacer element 35 may be pulled individually.

[0122] The cord(s) 67 may be passed through the handles of the spacer elements before the plurality of studs is moved towards the top tower section flange, even before the plurality of studs is gripped by the tool 1 . In other examples, the cord(s) may be joined to the spacer elements after the plurality of studs is partially introduced in the through holes of the top tower section flange and e.g. the tool 1 has been removed.

[0123] Remaining through holes 51 of the top wind turbine component 47 may be populated as previously explained. I.e., steps 110 - 150 may be repeated until all the necessary through holes have been filled with studs.

[0124] The studs which, when arranged within the through holes 51 , lie on the support(s) 63 for the top wind turbine component 47, see figure 7, may be completely inserted after the top wind turbine component 47 is lifted. If spacer elements 35 are used, they may be removed after thetop wind turbine component 47 is lifted from the support(s) 63 and after the top wind turbine component is arranged on top of the bottom wind turbine component.

[0125] The method may further comprise lifting the top wind turbine component 47 with the plurality of studs, arranging the top wind turbine component 47 above a bottom wind turbine component, inserting the plurality of studs through a plurality of through holes of a flange of the bottom wind turbine component and tightening the plurality of studs to attach the bottom wind turbine component to the top wind turbine component.

[0126] The studs already passing through the through holes of the top wind turbine component may therefore pass through the through holes of the bottom wind turbine component, e.g. another tower section. Once the studs connect the top and bottom wind turbine components, the studs may be tightened. For example, nuts may be arranged in the bottom portion of the studs, thereby securing the top and bottom wind turbine components.

[0127] As previously explained, if a plurality of spacer elements is used, the through holes 51 of the top wind turbine component 47 may be first populated with the fasteners. The spacers 35 may support the fasteners 43 such that the fasteners do not protrude below the through holes 51 of the top wind turbine component 47. The top wind turbine component 47 may be lifted with the fasteners and the spacer elements 35, and the through holes of the top and bottom wind turbine components may be aligned. Inserting the plurality of fasteners through the plurality of through holes of a flange of the bottom wind turbine component may comprise removing the spacer elements 35. Removing the spacer elements 35 may for example comprise pulling a cord 67 connected to the spacer elements 35, see the examples of figures 9 and 10.

[0128] The features and explanations of the previous aspects, e.g. with respect to figures 1 - 4, may also apply to, and combined with, the features and explanations of this aspect, e.g. with respect to figures 5 - 10, and vice versa.

[0129] This written description uses examples to disclose a teaching, including the preferred embodiments, and also to enable any person skilled in the art to put the teaching into practice, including making and using any devices or systems and performing any incorporated methods. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Aspects from the various embodiments described, as well as other known equivalents for each such aspects, can be mixed and matched by one of ordinary skill in the art to construct additional embodiments and techniques in accordance with principles of this application. If reference signs related to drawings are placed in parentheses in a claim, they are solely forattempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim.

Claims

CLAIMS1. A tool (1) for gripping a plurality of fasteners (43) to be inserted in a plurality of through holes (51) of a wind turbine component (47) having a first pitch, wherein the through holes (51) are arranged along an imaginary line having a first curvature, the tool (1) comprising: a first spreader bar (3) including a plurality of recesses (27) configured to receive the plurality of fasteners (43); a frame (2) configured to support the first spreader bar (3); wherein the plurality of recesses (27) of the first spreader bar (3) is arranged along an imaginary line having the first curvature; and wherein the recesses of the plurality of recesses (27) of the first spreader bar (3) have the first pitch.

2. The tool of claim 1 , wherein the first spreader bar (3) is removably attached to the frame (2) of the tool (1).

3. The tool of claim 1 or claim 2, wherein the frame (3) comprises flanges (8, 9) for supporting the first spreader bar (3).

4. The tool of any of claims 1 - 3, wherein the tool (1) further comprises a top cover plate (23) rotatably connected to the frame (2) for limiting a movement of the fasteners (43) when transporting the fasteners (43) to the plurality of through holes (51) of the wind turbine component (47).

5. The tool of any of claims 1 - 4, wherein the first spreader bar (3) comprises a first plate portion (31) comprising the plurality of recesses (27) and a second plate portion (33) extending from a side of the first plate portion (31) opposite to a side including the plurality of recesses (27).

6. A tool kit comprising: the tool (1) of any of claims 1 - 5; and a plurality of spacer elements (35) configured to be removably inserted in the plurality of recesses (27) of the first spreader bar (3) and configured to receive the plurality of fasteners (43); optionally wherein the spacer elements (35) comprise first flanges (37) at one end of the spacer elements (35) and second flanges (39) at an opposite end of the spacer elements (35).

7. A tool kit comprising: the tool (1) of any of claims 1 - 5; and an additional spreader bar including a plurality of recesses configured to receive a plurality of fasteners; wherein a size of the recesses, and / or a pitch between recesses, and / or a number of recesses and / or a curvature of an imaginary line joining the plurality of recesses, is different from the corresponding features of the first spreader bar (3).

8. A system for gripping and carrying fasteners (43) for a wind turbine comprising: a column (55); an arm (57) attached to the column (55) and configured to horizontally move the tool (1) of any of claims 1 - 5, optionally wherein the arm (57) is a flexible arm; and a lifting device (49) connected to the arm (57) and carrying the tool (1) of any of claims 1 - 5; wherein the lifting device (49) is configured to vertically move the tool (1).

9. A method (100) comprising: arranging (110) a tool (1) having a spreader bar (3) in proximity of a plurality of fasteners (43); arranging (120) the spreader bar (3) such that a plurality of recesses (27) of the spreader bar (3) is arranged around the plurality of fasteners (43); lifting (130) the tool (1) and thereby lifting the fasteners (43); placing (140) the plurality of fasteners (43) above a plurality of through holes (51) of a top wind turbine component (47); and inserting (150) the plurality of fasteners (43) in the plurality of through holes (51), wherein the recesses (27) of the spreader bar (3) have a pitch corresponding to a pitch of the through holes (51) of the top wind turbine component (47) and wherein the recesses (27) are arranged along an imaginary line having a curvature corresponding to a curvature of the through holes (51) of the top wind turbine component (47).

10. The method of claim 9, further comprising populating remaining through holes (51) of the top wind turbine component (47) by repeating the steps of arranging (110) the tool (1), arranging (120) the spreader bar (3), lifting (130), placing (140) and inserting (150).

11. The method of claim 10, further comprising: lifting the top wind turbine component (47) with the plurality of fasteners (43); arranging the top wind turbine component (47) above a bottom wind turbine component; inserting the plurality of fasteners (43) through a plurality of through holes of a flange of the bottom wind turbine component; and tightening the plurality of fasteners (439 for attaching the bottom wind turbine component to the top wind turbine component (47).

12. The method of claim 11 , further comprising arranging a plurality of spacer elements (35) in the plurality of recesses (27) of the spreader bar (3) before arranging the spreader bar (3) such that the plurality of recesses (27) of the spreader bar (3) is arranged around the plurality of fasteners (43).

13. The method of claim 12, wherein inserting (150) the plurality of fasteners (43) in the plurality of through holes (51) of the top wind turbine component (47) comprises partially inserting the plurality of fasteners (43) in the plurality of through holes (51) and resting the spacer elements (35) on a flange including the plurality of through holes (51); and wherein inserting the plurality of fasteners through a plurality of through holes of a flange of the bottom wind turbine component comprises removing the spacer elements (35).

14. The method of claim 13, wherein removing the spacer elements (35) comprises pulling a cord (67) connected to the spacer elements (35).

15. The method of any of claims 9 - 14, wherein the top wind turbine component (47) is a tower section.

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