DK179522B1

DK179522B1 - Method and tool for blade replacement and installation

Info

Publication number: DK179522B1
Application number: DKPA201770118A
Authority: DK
Inventors: Krag Nielsen Thomas
Original assignee: Envision Energy (Denmark) Aps
Priority date: 2017-02-20
Filing date: 2017-02-20
Publication date: 2019-02-06
Also published as: DK201770118A1; CN110300848B; WO2018149372A1; CN110300848A

Abstract

Blade replacement and installation tool for a wind turbine, comprising a lever arm with a first end and a second end, where the tool further comprises: at least one gear motor, one bearing and one gear ring which are relatively arranged at the first end of the lever arm, the gear motor being fixed to the lever arm and the gear ring being configured for installation on a hub, where the gear ring is geared with theat least one gear motor, where the bearing is positioned between the gear ring and the lever arm and where a flexible connection member is arranged at the second end of the lever arm configured for fixation to a ground fixation point, whereby a less complicated, easier to use and much safer tool for operating a wind turbine is achieved.

Description

Method and tool for blade replacement and installation

Field of the Invention

The present invention relates to a blade replacement and installation tool for a wind turbine, comprising a lever arm with a first end and a second end and where a flexible connection member is arranged at the second end of the lever arm.

The invention further relates to a method for replacement and installation of a blade on a hub on a wind turbine tower, where the wind turbine has a rotor lock.

Background of the Invention

Before the development of the present invention, other ways to replace and install blades at wind turbines were known, e.g. from:

US 2016/090962 A1 where a counterweight system for a wind turbine is provided, where the system comprises a beam comprising a connection element adapted to be attached to the mounting surfaces, where the system comprises a counterweight mass coupled to the beam.

EP 2650537 A1 where a counterweight is attached to the hub, whereby the counter weight comprises a mass that leads to a counter-torque around the axis of rotation of the hub. The counter weight is mounted to the hub by a mechanical arrangement that is rotatable in respect to the hub around the axis of rotation of the hub.

DE 102009011603 A1 where the device has counterweights arranged at different distances to a rotation axis and actively moves along a guide by a drive. Multiple ballast tanks are connected with each other by a line and a conveying device so that the centre of gravity position is changed by moving material from one of the tanks to the other tank.

Common for the above mentioned prior art documents are the use of at least one counterweight for rotation of the hub into the right position for the mounting of a blade.

With a blade weighing for example 15 tons, the use of counterweights for rotation is very challenging, difficult and dangerous and the risk of making errors in the adjustments could have fatal consequences.

Furthermore DE 1020099013876 A1 discloses a blade replacement and installation tool for a wind turbine as described in the opening clause. The tool comprises a lever arm with a first end and a second end. A flexible connection member is arranged at the second end of the lever arm. The tool does not comprise a motor which makes it possible to apply a torque on the hub and blades (if any is mounted) and thereby turn it into the next position for the mounting of the first or subsequent blade.

Object of the Invention

The object of this invention is therefore to provide a blade replacement and installation tool for a wind turbine of the type mentioned in the introduction, which is less complicated, easier to use and much safer to operate.

It is a further object of the invention to avoid the complexity in turning the hub by means of the gear inside the nacelle.

Description of the Invention

According to a first aspect of the invention, the above object is achieved with a blade replacement and installation tool for a wind turbine of the type mentioned in the introduction, comprising a lever arm with a first end and a second end, the tool further comprising:

at least one gear motor, one bearing and one gear ring which are relatively arranged at the first end of the lever arm, the gear motor being fixed to the lever arm and the gear ring being configured for installation on a hub, where the gear ring is geared with the at least one gear motor, where the bearing is positioned between the gear ring and the lever arm and that said flexible connection member is configured for fixation to a ground fixation point.

This makes it possible to provide a blade replacement and installation tool for a wind turbine, which is less complicated, easier to use and much safer to operate than prior art solutions, and where no counterweights are necessary.

By conducting and controlling the replacement and installation of a blade on a hub on a wind turbine tower through a lever arm connected to a flange at the hub, where from the tool is operable for replacement and installation of all blades, the complexity in turning the hub by means of the gear in the nacelle is thus avoided. The solution used instead is a so-called direct drive configuration, whereby the gear in the nacelle is not exposed to the extreme load level made up by the torque and the weight of the blades together with the aerodynamic influence.

The blade replacement and installation tool is basically a rotor turning device, where no blades are mounted yet, just a hub turning device. Compared to the yaw system of a wind turbine, the present invention with its blade replacement and installation tool does limit the load and forces with the lever arm and the flexible connection member connected to the ground fixation. The longer the lever arm is, and it could e.g. be 20 metres, the more it counteracts with the gravity load from the blade, hence the forces are reduced. Thus, the invention is not as dynamic as the yaw system, but there is more control with the forces and the security at the site of operation.

By including at least one gear motor in the invention it is possible to apply a torque on the hub and blades (if any is mounted) and thereby turn it into the next position for the mounting of the first or subsequent blade.

The lever arm could be a one piece construction or it could of course be collected from a number of smaller elements, the lever arm could be solid steel or made up of a number of pipes, poles etc. and it could be made in a large variety of materials or a combination of materials. The cross section could be the same throughout the lever arm or it could be different, thus a lot of options apply.

With the flexible connection member, which could be e.g. wire, chain, rope or cables, where the flexible connection member is arranged at the second end of the lever arm, the fixation to a ground fixation point is possible and easy to conduct. The flexible connection member could be exposed to a load equivalent to 20-30 ton, so the fixation to the ground fixation point, which for example could be the foundation, is very important and could be made by embedding fittings, plates etc.

In a second aspect, the present invention also relates to a blade replacement and installation tool, the gear ring configured for installation on a hub, where a hub has a front end with a flange and a back end adapted for installation with a main shaft, where the gear ring and the flange on the front end of the hub has a centreline coincident with a centreline of an installed wind turbine rotor shaft.

This makes it possible to mount the blade replacement and installation tool at a flange on the front end of the hub, in a position from where the centre of rotation does not move relative to the height of the ground. That means that, in an optimal set up, the lever arm and its flexible connection member could be arranged and fixed in the same position throughout the whole mounting of the wind turbine blades.

Furthermore, it is easier and more convenient to get to the flange on the front of the hub and, thereby, mount the blade replacement and installation tool on the hub.

When the gear ring and the flange on the front end of the hub has a centreline coincident with a centreline of an installed wind turbine rotor shaft the construction is overall prepared for loads and torques in relation to the centreline and hence, possible damages to the wind turbine are to be considered less likely than if the flange was positioned elsewhere on the hub compared to the centreline of an installed wind turbine rotor shaft.

In a third aspect, the present invention also relates to a blade replacement and installation tool, where the gear ring is geared with the at least one gear motor on the outer periphery of the gear ring.

This makes it possible to turn the gear ring with great precision due to the longer distance on the outer periphery of the gear ring, making it an external gear, compared to the same gearing used at the inner periphery, making it an internal gear, which of course is also an option.

In a fourth aspect, the present invention also relates to a blade replacement and installation tool, where the tool further comprises at least one further gear motor geared with the gear ring, where an arc of a circle with a centreline coincident with the centreline of the gear ring is of the same distance between the gear motors.

This makes it possible to equalize the stress on the individual gear motor and minimize the risk of overload and failure, when larger numbers of gear motors are used. Furthermore, the force and torque at the gear ring are more even, if more gear motors are used, as the distances between the individual gear motors are the same. An alternative option is to make the distances between the individual gear motors vary.

In a fifth aspect, the present invention also relates to a blade replacement and installation tool, where the at least one gear motor is arranged parallel to the centreline of the gear ring.

This makes it possible to use straight-cut gearwheels which are a less complicated solution. Other options are e.g. helical or bevel gears.

In a sixth aspect, the present invention also relates to a blade replacement and installation tool, where the lever arm is situated on a plane orthogonal to the centreline of the gear ring.

This makes it possible to use the blade replacement and installation tool, but it might also be necessary to demount the tool completely or at least to turn it into another position during the blade replacement and installation process, at least where the blade construction makes it impossible to turn the hub with blades past the tool. In such a case the problem is typically due to pre-bend blade constructions.

In a seventh aspect, the present invention also relates to a blade replacement and installation tool, where at least the first end of the lever arm is situated on a plane orthogonal to the centreline of the gear ring and that at least the second end of the lever arm is bent away from and situated at a distance from the plane.

This makes it possible to use the blade replacement and installation tool, without having to demount the tool during the blade replacement and installation process, in cases where the blade construction due to pre-bend blade constructions deviate from the mentioned plane. Of course the lever arm needs to be bent away from and situated at a distance from the plane, in the direction away from the wind turbine tower and with sufficient distance to avoid collision to the pre-bend blades.

In an eight aspect, the present invention also relates to a blade replacement and installation tool, where the lever arm is at least 20 metres long.

This makes it possible to minimize the forces used to hold the lever arm, compared to a lever arm half the length. In principle, a lever arm of any length will work however, the longer the lever arm is the more the forces are reduced.

In a ninth aspect, the present invention also relates to a blade replacement and installation tool, where the ground fixation point is selected from one of: a concrete anchor in the foundation, an anchor flange at the tower bottom flange, a concrete block, etc.

This makes it possible to use a number of options, and whatever option is available at the present site. Where the flexible connection member could be exposed to a load equivalent to 20-30 ton, the fixation to the ground fixation point is extremely important and should not be neglected.

In a tenth aspect, the present invention also relates to a blade replacement and installation tool, where the tool further comprises at least a power cable and a control cable alongside the flexible connection member.

This makes it possible to get the necessary power and control, needed for the blade replacement and installation tool, to the tool when mounted on the hub by using the flexible connection member. In an option the power and control cables could be fastened to the outside of the flexible connection member and in yet another option the power and control cables could be integrated and thus, protected within the flexible connection member.

In an eleventh aspect, the present invention also relates to a blade replacement and installation tool, where the tool further comprises at least a power pack and a wireless communication device.

This makes it possible to avoid the use of any cables by mounting the power pack and the wireless communication device at the blade replacement and installation tool, for example at the second end of the lever arm.

In a twelfth aspect, the present invention also relates to a method for replacement and installation of a blade on a hub on a wind turbine tower, where the wind turbine has a rotor lock and where the method comprises the steps of:

a) a blade replacement and installation tool according to any of claims 1 to 11 is installed on a hub,

b) the hub is rotated to a position where it is possible to mount a blade horizontally,

c) the rotor lock is set and a blade is mounted on the hub,

d) the rotor lock is released and the hub is rotated,

e) steps b), c) and d) are repeated until the wanted numbers of blades are replaced and installed,

f) the blade replacement and installation tool is removed.

This makes it possible, with the use of a blade replacement and installation tool, to conduct a complete installation of blades on a hub, where the hub is installed at a wind turbine tower and where the wind turbine has a rotor lock. There could possibly be more steps than the ones mentioned depending e.g. on the blade structure.

In a thirteenth aspect, the present invention also relates to a method for replacement and installation of a blade on a hub of a wind turbine, where the method according to step c) further comprises the mounting of a blade with the trailing edge upwards.

This makes it possible to mount the blade in such a way that the leading edge is in a downward horizontal position which is an advantage, as the leading edge has a much larger and stronger surface than the trailing edge, hence, it is less volatile. When a blade might have a weight of 15 ton it is very important how the blades are treated, handled and mounted.

Description of the Drawing

The invention will be described in further detail below by means of non-limiting embodiments with reference to the drawing, in which:

Fig. 1 shows an exemplary embodiment of a wind turbine with a rotor assembly,

Fig. 2 shows a blade replacement and installation tool,

Fig. 3 shows a sectional view of a blade replacement and installation tool mounted at a hub,

Fig. 4 shows a lever arm in one embodiment schematic,

Fig. 5 shows a lever arm in another embodiment schematic,

Fig. 6 shows step 1 of a method for replacement and installation of a blade on a hub on a wind turbine tower,

Fig. 7 shows step 2 of a method for replacement and installation of a blade on a hub on a wind turbine tower,

Fig. 8 shows step 3 of a method for replacement and installation of a blade on a hub on a wind turbine tower,

Fig. 9 shows step 4 of a method for replacement and installation of a blade on a hub on a wind turbine tower,

Fig. 10 shows step 5 of a method for replacement and installation of a blade on a hub on a wind turbine tower,

Fig. 11 shows step 6 of a method for replacement and installation of a blade on a hub on a wind turbine tower,

Fig. 12 shows step 7 of a method for replacement and installation of a blade on a hub on a wind turbine tower,

In the drawings, the following reference numerals have been used for the designations used in the detailed part of the description:

Wind turbine

Wind turbine tower

Foundation

Nacelle

Rotor

Hub

6a

6b

Hub, front end

Hub, back end

Wind turbine blades

Blade replacement and installation tool

Lever arm

First end, lever arm

Second end, lever arm

Gear motor

Bearing

Gear ring

14a Outer periphery

Flexible connection member

15a Power cable

15b Control cable

15c Power pack

15d Wireless communication device

Ground fixation point

Flange, hub front end

Main shaft

Blade bearing

Centreline, gear ring and flange

Centreline, main shaft and rotor shaft

Arc of circle, between gear motors

Centreline, arc of circle between gear motors

Plane

Trailing edge

Detailed Description of the Invention

Figure 1 shows an exemplary embodiment of a wind turbine 1 with a rotor assembly.

The wind turbine 1 comprises a wind turbine tower 2 having a bottom end mounted to a foundation 3 which may be an onshore foundation as well as an offshore foundation.

A nacelle 4 is rotatable connected to a top end of the wind turbine tower 2, e.g. via a yaw bearing connected to a control system (not shown). A rotor 5 is rotatable connected to the nacelle 4, e.g. via a main shaft (not shown). The rotor 5 comprises a hub 6 to which at least two, e.g. three, wind turbine blades 7 are mounted. Each wind turbine blade comprises a tip end and a blade root. The hub 6 comprises a front end 6a facing away from the nacelle 4 and a back end 6b facing the nacelle 4. The wind turbine blades 7 may be traditional full-span pitch able blades as shown in fig. 1 or partial pitch able blades (not shown) having an inner blade section and outer blade section. A pitch bearing (not shown) is arranged between the hub 6 and wind turbine blade 7 or between the inner and outer blade sections of the wind turbine blade 7.

Figure 2 shows a blade replacement and installation tool 8 for a wind turbine 1, comprising a lever arm 9 with a first end 10 and a second end 11, where four gear motors 12, a bearing 13 and a gear ring 14 are relatively arranged at the first end 10 of the lever arm 9.

The gear motors 12 are fixed to the lever arm 9 and the gear ring 14 is configured for installation on a hub 6, where the gear ring 14 is geared with the gear motors 12, and where the bearing 13 is positioned between the gear ring 14 and the lever arm 9. The gear ring 14 is geared with the gear motors 12 on the outer periphery of the gear ring 14.

A flexible connection member 15 is arranged at the second end 11 of the lever arm 9 configured for fixation to a ground fixation point 16 e.g. the foundation 3. Alongside, e.g. inside or outside the flexible connection member 15 is at least a power cable 15a and a control cable 15b. Another option to a power cable 15a and a control cable 15b is a power pack 15c and a wireless communication device 15d.

Figure 3 shows a sectional view of a blade replacement and installation tool 8 mounted via the gear ring 14 at the front end 6a of a hub 6 which is provided with a flange 17, and where the back end 6b of the hub 6 is mounted at the main shaft 18. The hub 6 also shows two blade bearings 19. The gear ring 14 and the flange 17 on the front end 6a of the hub 6 has a centreline 20 coincident with a centreline 21 of the main shaft 18 and an installed wind turbine rotor shaft (not shown).

The figure also shows that the tool 8 has the gear motors 12 geared with the gear ring 14, where the gear motors 12 are spaced apart in such a way that an arc of a circle 22 between two gear motors 12 where the centreline 23 is coincident with the centreline of the gear ring 20 is of the same distance between two individual gear motors 12 no matter if it is clockwise or anticlockwise, and no matter between which two individual gear motors 12. The gear motors 12 are all arranged parallel to the centreline 20 of the gear ring 14.

Figure 4 shows a lever arm 9 schematic which is situated on a plane 24 which is orthogonal to the centreline 20 of the gear ring 14.

Figure 5 shows the first end 10 of a lever arm 9 schematic situated in a plane 24 orthogonal to the centreline 20 of the gear ring 14 and where the second end 11 of the lever arm 9 is bent away from and situated at a distance from the plane 24.

Figure 6 to figure 12 shows the most important steps in a method for replacement and installation of a blade on a hub on a wind turbine tower, where the wind turbine has a rotor lock, comprising the following steps explained by means of a clock and its rotation, when looking at the front end 6a of the hub 6:

Figure 6 shows step 1 of a method for replacement and installation of a blade 7 on a hub 6 on a wind turbine tower 2, where a blade replacement and installation tool 8 is installed on the front end 6a of a hub 6 in a horizontal position to the left, at 9 o'clock.

Figure 7 shows step 2 of a method for replacement and installation of a blade 7 on a hub 6 on a wind turbine tower 2, where the hub 6 is rotated and a rotor lock (not shown) is set in a position, wherein a blade 7 it is possible to mount a blade horizontally with the trailing edge 25 upwards and to the right, at 3 o'clock.

Figure 8 shows step 3 of a method for replacement and installation of a blade 7 on a hub 6 on a wind turbine tower 2, where the rotor lock is released and the hub 6 with the first mounted blade 7 is rotated 60 degrees clockwise, where after the rotor lock is set again.

Figure 9 shows step 4 of a method for replacement and installation of a blade 7 on a hub 6 on a wind turbine tower 2, where the lever arm 9 is rotated 180 degrees to 3 o'clock and the rotor lock is set. This step could be necessary in situations where prebend wind turbine blades 7 are mounted.

Figure 10 shows step 5 of a method for replacement and installation of a blade 7 on a hub 6 on a wind turbine tower 2, where the rotor lock is set in a position, wherein a blade 7it is possible to mount a blade horizontally with the trailing edge 25 upwards and to the left, at 9 o'clock.

Figure 11 shows step 6 of a method for replacement and installation of a blade 7 on a hub 6 on a wind turbine tower 2, where the mounted blades 7 are rotated 60 degrees clockwise, where after the rotor lock is set again and where it is possible to mount a blade 7 horizontally.

Figure 12 shows step 7 of a method for replacement and installation of a blade 7 on a hub 6 on a wind turbine tower 2, where all blades 7 are mounted at the hub 6 and the rotor, being hub 6 and blades 7, is then complete.

What is not shown in the figures is the removal of the blade replacement and installation tool 8.

Claims

1. Vingeudskiftnings- og installationsværktøj til en vindturbine, omfattende en vægtarm med en første ende og en anden ende, og hvor der er arrangeret et fleksibelt element ved vægtarmens anden ende, kendetegnet ved at værktøjet yderligere omfatter:A wing replacement and installation tool for a wind turbine, comprising a lever with a first end and a second end, and wherein a flexible element is arranged at the second end of the lever, characterized in that the tool further comprises:

- mindst en gearmotor, et leje og en tandkrans, som er arrangeret i forhold dertil ved vægtarmens første ende, hvor gearmotoren er fikseret til vægtarmen, og tandkransen er konfigureret til installation på et nav, hvor tandkransen er i tandhjulsindgreb med den mindst ene motor, hvor lejet er placeret mellem tandkransen og vægtarmen, og hvor det fleksible forbindelseselement er konfigureret til fiksering på et jordfikseringspunkt.at least one gear motor, a bearing and a ring gear arranged relative thereto at the first end of the lever arm, the gear motor being fixed to the lever arm and the gear ring being configured for installation on a hub, the ring gear being in gear engagement with the at least one motor, wherein the bearing is located between the ring gear and the lever arm, and wherein the flexible connecting member is configured for fixation at a ground fixation point.

2. Vingeudskiftnings- og installationsværktøj ifølge krav 1, kendetegnet ved at tandkransen er konfigureret til installering på et nav, hvor et nav har en forende med en flange og en bagende indrettet til installation med en hovedaksel, hvor tandkransen og flangen på navets forende har en centerlinie sammenfaldende med en centerlinie af en installeret vindturbinerotoraksel.Wing replacement and installation tool according to claim 1, characterized in that the ring gear is configured for installation on a hub, a hub having a front end with a flange and a rear end arranged for installation with a main shaft, the ring gear and the flange on the front end of the hub having a centerline coinciding with a centerline of an installed wind turbine rotor shaft.

3. Vingeudskiftnings- og installationsværktøj ifølge ethvert af krav 1 og 2, kendetegnet ved at tandkransen er i tandhjulsindgreb med den mindst ene gearmotor på tandkransens ydre periferi.Wing replacement and installation tool according to any one of claims 1 and 2, characterized in that the ring gear is in gear engagement with the at least one gear motor on the outer periphery of the gear ring.

4. Vingeudskiftnings- og installationsværktøj ifølge ethvert af krav 1 til 3, kendetegnet ved at værktøjet yderligere omfatter mindst en yderligere gearmotor i tandhjulsindgreb med tandkransen, hvor en cirkelbue med en centerlinie sammenfaldende med tandkransens centerlinie er med samme afstand mellem gearmotorerne.Wing replacement and installation tool according to any one of claims 1 to 3, characterized in that the tool further comprises at least one further gear motor in gear engagement with the gear ring, wherein a circular arc with a center line coinciding with the center line of the gear ring is with the same distance between the gear motors.

5. Vingeudskiftnings- og installationsværktøj ifølge ethvert af krav 1 til 4, kendetegnet ved at den mindst ene gearmotor er arrangeret parallelt med tandkransens centerlinie.Wing replacement and installation tool according to any one of claims 1 to 4, characterized in that the at least one gear motor is arranged parallel to the center line of the gear ring.

6. Vingeudskiftnings- og installationsværktøj ifølge ethvert af krav 1 til 5, kendetegnet ved at vægtarmen er placeret i et plan vinkelret på tandkransens centerlinie.Wing replacement and installation tool according to any one of claims 1 to 5, characterized in that the weight arm is located in a plane perpendicular to the center line of the ring gear.

7. Vingeudskiftnings- og installationsværktøj ifølge ethvert af krav 1 til 5, kendetegnet ved at i det mindste den første ende af vægtarmen er placeret i et plan vinkelret på tandkransens centerlinie, og at i det mindste den anden ende af vægtarmen er bukket væk fra og placeret i afstand fra planet.Wing replacement and installation tool according to any one of claims 1 to 5, characterized in that at least the first end of the weight arm is located in a plane perpendicular to the center line of the ring gear and that at least the other end of the weight arm is bent away from and located at a distance from the planet.

8. Vingeudskiftnings- og installationsværktøj ifølge ethvert af krav 1 til 7, kendetegnet ved at vægtarmen er mindst 20 m lang.Wing replacement and installation tool according to any one of claims 1 to 7, characterized in that the weight arm is at least 20 m long.

9. Vingeudskiftnings- og installationsværktøj ifølge ethvert af krav 1 til 8, kendetegnet ved at jordfikseringspunktet er valgt blandt en af: et betonanker i fundamentet, en forankringsflange ved tårnets bundflange, en betonklods, etc.Wing replacement and installation tool according to any one of claims 1 to 8, characterized in that the ground fixing point is selected from one of: a concrete anchor in the foundation, an anchoring flange at the bottom flange of the tower, a concrete block, etc.

10. Vingeudskiftnings- og installationsværktøj ifølge ethvert af krav 1 til 9, kendetegnet ved at værktøjet yderligere omfatter mindst et strømkabel og et styrekabel langs det fleksible forbindelseselement.Wing replacement and installation tool according to any one of claims 1 to 9, characterized in that the tool further comprises at least one power cable and a control cable along the flexible connecting element.

11. Vingeudskiftnings- og installationsværktøj ifølge ethvert af krav 1 til 10, kendetegnet ved at værktøjet yderligere omfatter mindst en strømforsyningsenhed og en trådløs kommunikationsindretning.Wing replacement and installation tool according to any one of claims 1 to 10, characterized in that the tool further comprises at least one power supply unit and a wireless communication device.

12. Fremgangsmåde til udskiftning og installation af en vinge på et nav i et vindturbinetårn, hvor vindturbinen har en rotorlås, kendetegnet ved at fremgangsmåden omfatter trinene:Method for replacing and installing a blade on a hub in a wind turbine tower, the wind turbine having a rotor lock, characterized in that the method comprises the steps of:

a) et vingeudskiftnings- og installationsværktøj ifølge ethvert af krav 1 til 11 installeres på et nav,a) a wing replacement and installation tool according to any one of claims 1 to 11 is installed on a hub,

b) navet drejes til en position, hvor det er muligt at montere en vinge vandret,b) the hub is turned to a position where it is possible to mount a wing horizontally,

c) rotorlåsen låses, og vingen monteres på navet,c) the rotor lock is locked and the blade is mounted on the hub,

d) rotorlåsen frigøres, og navet drejes,d) the rotor lock is released and the hub is turned,

e) trinene b), c) og d) gentages indtil det ønskede antal vinger er udskiftet og installeret,e) steps b), c) and d) are repeated until the desired number of wings has been replaced and installed,

f) vingeudskiftnings- og installationsværktøjet fjernes.f) the wing replacement and installation tool is removed.

13. Fremgangsmåde til udskiftning og installation af en vinge på et nav i en vindturbine ifølge krav 12, kendetegnet ved at fremgangsmåden ifølge trin c) yderligere omfatter montering af en vinge med bagkanten opad.Method for replacing and installing a blade on a hub in a wind turbine according to claim 12, characterized in that the method according to step c) further comprises mounting a blade with the rear edge upwards.