FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
METHOD FOR ASSEMBLING ROTOR BLADES OF WIND TURBINES;
SUZLON ENERGY LIMITED A COMPANY
INCORPORATED UNDER THE
COMPANIES ACT, 1956, WHOSE ADDRESS IS UNIT NO. 6, BLOCK NO. 93, VILLAGE: VADASALA - VARNAMA, N. H. NO. 8, DISTRICT: VADODARA - 391 242, GUJARAT, INDIA
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE INVENTION
The present invention relates to wind turbines. More particularly, the invention relates to method for assembling rotor blades of wind turbines.
BACKGROUND OF THE INVENTION
Wind turbines are well known for exploiting the power of wind energy. Over the years, many multi-megawatt turbine technologies such as steel tube towers, variable-speed generators, composite blade materials, partial-span pitch control, as well as aerodynamic, structural, and acoustic engineering design capabilities have been undergoing continuous research and development. Reciprocity between the length of the blade and power output encouraged the development and manufacturing of large wind turbines with the longer rotor blades over the time.
Generally, a wind turbine includes a rotor having multiple wind turbine blades. The wind turbine blades are elongated airfoils devised to provide rotational forces in response to wind. With the use of larger rotor blades on wind turbines, numbers of engineering challenges have occurred. Rotor blades of wind turbines are exposed to high and changing loads. The rigidity and aerodynamic quality of the rotor blades particularly depends upon one or more shear webs that are longitudinally directed load bearing members extending along the inside of two shell halves of the blade. Numerous different methods for assembling rotor blades are known in the state of art.

In one of the conventional method for assembling a rotor blade, the first half shell also referred to as a lower shell of the rotor blade is first arranged in the reception device or in mould that is open on the top or on a suitable frame so that its inner surface points up. Adhesive is applied to the lower shell in the connection area between the lower shell and shear webs. The shear webs are lowered and placed to the desired position onto the lower shell either using a crane or using hoisting devices. Adhesive is then applied in the connection area between the shell halves and in the connection area between the shear webs and the upper shell, then upper shell is fitted on the lower shell already installed with the shear webs, closing the inner surfaces of both the shells along with the shear webs.
In the cases, where crane is used to place the shear webs at the desired position on the lower shell, installation of the shear webs is accomplished on an individual basis. In such cases, a first shear web is lowered and placed on the lower shell at the desired position and curing of the adhesive takes place, than only second shear web is lowered and placed at the desired position on the lower shell and curing of corresponding adhesive takes place, once the curing for both the shear webs is completed then only the lower shell is closed by the upper shell.
The installation of shear webs using hoisting device are available with variety of holding mechanisms to lift the shear webs. Hoisting device are having the holding mechanism by means of vacuum tool wherein the two shear webs are fastened to the device with the help of vacuum cups, lifted and placed in the shell at the same time, saving the time reducing the cycle time by fifty percent, taken by the process implementing the installation of the shear webs one after another. However, device described herein is expensive and method using the suggested device requires extra support tools and maintenance.

Further, use of hoisting device with the holding mechanism by means of pins inserted in the shear webs, lifted and placed in the shell at the same time, is also known in the art. For the insertion of the pins, shear webs comprises holes in its structure that may require the repair after installation in the shed. For the perforation of the holes in the shear web, moulds with specific marking for the perforation of the holes are required. Use of hoisting device described herein requiring moulds with specific marking for the shear webs and extra support tools for the installation of the shear webs in the shell ultimately are being undesirably expensive. Furthermore, method is complicated in handling due to wobbling of the shear webs in the air while lifted by the device hence being less user-friendly, and also requiring additional maintenance and extra space in the workshop.
The shear web setting apparatus suggested by the US/2011/0126978 comprises the plurality of load-bearing devices for the fastening of the one or more shear webs at a time. Use of the apparatus, shear web setting device, disclosed herein and others described above and known from the state of the art are difficult in handling of the shear webs while installation, particularly, for the application of pressure for squeezing of the adhesive. These being sophisticated tools, are expensive, requiring extra support tools, storage area and maintenance for the same.
Hence, a need continues to exist for an improved method for assembling a rotor blade without damaging the shear webs providing easy handling and easy assembling in an economic and user friendly manner.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a method for assembling a rotor blade of a wind turbine wherein the rotor includes a lower shell and an upper

shell. The method comprises the steps of positioning the lower shell and the upper shell, identifying a first fastening area on each shell; fastening the first shear web at the first fastening area on an inner surface of the lower shell and the.second shear web at the first fastening area on an inner surface of the upper shell; and fixing the lower shell and the upper shell thereby assembling the rotor blade.
In an embodiment, the fixing of lower shell and upper shell for assembling the rotor blade includes the step of applying adhesive at extreme ends of the lower shell; and applying adhesive on top of the first shear web and at a second fastening area on the inner surface of the lower shell for fastening the first shear web to the upper shell and for fastening the second shear web to the lower shell.
In an embodiment, the fixing of the lower shell and upper shell for assembling the rotor blade includes step of applying adhesive at extreme ends of the lower shell; and applying adhesive on top of the second shear web and at a second fastening area on the inner surface of the upper shell for fastening the second shear web to the lower shell and fastening the first shear web to the upper shell.
In an embodiment, the fixing of the lower shell and upper shell for assembling the rotor blade includes step of applying adhesive at extreme ends of the lower shell; and applying adhesive at a second fastening area on the inner surface of the lower shell and at a second fastening area on the inner surface of the upper shell for fastening the second shear web to the lower shell and fastening the first shear web to the upper shell.
In an embodiment, the fixing of the lower shell and upper shell for assembling the rotor blade includes step of applying adhesive at extreme ends of the lower shell; and applying adhesive on top of the first shear web and on top of the second

shear web for fastening the second shear web to the lower shell and fastening the first shear web to the upper shell.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 shows method steps 1A through to 1F for assembling a wind turbine rotor having an upper shell and a lower shell in accordance with an embodiment of the invention.
Figure 2A shows a cross-sectional view of rotor blade with jigs holding shear webs in accordance with an embodiment of the invention.
Figure 2B shows a cross sectional view of rotor blade according to an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Various embodiments of the invention provide a method for assembling a rotor blade of a wind turbine wherein the rotor includes a lower shell and an upper shell. The method comprises the steps of positioning the lower shell and the upper shell, identifying a first fastening area on each shell; fastening the first shear web at the first fastening area on an inner surface of the lower shell and the second shear web at the first fastening area on an inner surface of the upper

shell; and fixing the lower shell and the upper shell thereby assembling the rotor blade.
In an embodiment, the lower shell and the upper shell are positioned on receiving device (not shown).
In an embodiment the present invention provides a rotor blade of a wind turbine, the rotor blade comprising a lower shell and an upper shell to be fixed to each other; and at least two shear webs to be fastened on an inner surface of the lower shell and an inner surface of the upper shell.
In an embodiment, the shear webs are fastened to the shells of the rotor blade by applying adhesive and curing.
In an embodiment, the adhesives are generally known adhesives in the art utilized for fastening.
In an embodiment, the process for positioning and fastening first shear web and second shear web one after the other and allowing curing of both the shear webs over the shells can be carried out simultaneously.
Figure 1A shows a lower shell (110) and an upper shell (120) of a rotor blade (100) in accordance with an embodiment of the invention.
The rotor blade (100) includes lower shell (110), upper shell (120), reception device (not shown) for receiving the shells (110, 120), a first shear web (112) fastened to the lower shell (110), a second shear web (122) fastened to the upper shell (120).

In an embodiment, the first shear web (112) is a tail shear web and the second shear web (122) is a nose shear web of the rotor blade (100).
Referring to Fig 1B and Fig 1C, the first shear web (112) is fastened at a first fastening area (110a) on an inner surface of the lower shell (110). The second shear web (122) is fastened at a first fastening area (120a) on an inner surface of the upper shell (120).
Figure 1B shows lower shell (110) and upper shell (120) of rotor blade (100) with adhesive applied at the first fastening area (110a) on the inner surface of the lower shell (110) and the first fastening area (120a) on the inner surface of the upper shell (120), in accordance with an embodiment of the invention.
Figure 1C shows lower shell (110) and upper shell (120) with first shear web (112) and second shear web (122) fastened to the shells (110, 120) respectively, in accordance with an embodiment to the invention.
Referring to Fig. 1D, the invention provides lower shell (110) with first shear web (112) fastened to the first fastening area (110a) and a second fastening area (110b) with adhesive applied for accommodating top of the second shear web (122) in accordance with an embodiment of the invention.
In an embodiment, the fixing of lower shell (110) and upper shell (120) for assembling the rotor blade (100) includes the step of applying adhesive at extreme ends (114a, 114b) of the lower shell (110); and applying adhesive on top (112a) of the first shear web (112) and at a second fastening area (110b) on the inner surface of the lower shell (110) for fastening the first shear web (112) to the upper shell (120) and for fastening the second shear web (122) to the lower shell (110).

In an embodiment, the fixing of the lower shell (110) and upper shell (120) for assembling the rotor blade (100) includes step of applying adhesive at extreme ends (114a, 114b) of the lower shell (110); and applying adhesive on top of the second shear web (122) and at a second fastening area (not shown) on the inner surface of the upper shell (120) for fastening the second shear web (122) to the lower shell (110) and fastening the first shear web (112) to the upper shell (120).
In an embodiment, the fixing of the lower shell (110) and upper shell (120) for assembling the rotor blade (100) includes step of applying adhesive at extreme ends (114a, 114b) of the lower shell (110); and applying adhesive at a second fastening area (110b) on the inner surface of the lower shell (110) and at a second fastening area (not shown) on the inner surface of the of the upper shell (120) for fastening the second shear web (122) to the lower shell (110) and fastening the first shear web (112) to the upper shell (120).
In an embodiment, the fixing of the lower shell (110) and upper shell (120) for assembling the rotor blade (100) includes step of applying adhesive at extreme ends (114a, 114b) of the lower shell (110); and applying adhesive on top of the first shear web (112) and on top of the second shear web (122) for fastening the second shear web (122) to the lower shell (110) and fastening the first shear web (112) to the upper shell (120).
In an embodiment, the fixing of the lower shell (110) and upper shell (120) is carried out by lowering the upper shell (120) on top of the lower shell (110) with the help of crane (not shown).
Figure 1E shows lower shell (110) with first shear web (112) and an upper shell (120) with second shear web (122), the upper shell (120) turning over the lower shell (110) in accordance with an embodiment of the invention.

In an embodiment, the fixing of the lower shell (110) and upper shell (120) by connecting the lower shell (110) and upper shell (120) at one end with the help of swivel and turning the upper shell (120) with the help of hydraulic hinge (not shown).
Hydraulic hinge is a revolving mechanism having a hinge joint. Hydraulic hinge is used for turning upper shell upside down on lower shell with the help of hydraulic power pack system.
Figure 1F shows upper shell (120) and lower shell (110) in closed position for assembling rotor blade (100) in accordance with an embodiment of the invention.
Referring to Figure 2A and 2B, cross-sectional view of rotor blade (100) with shear webs (112, 122) is shown in accordance with an embodiment of the invention.
In an embodiment, the fixing of the lower shell (110) and upper shell (120) for assembling the rotor blade (100) includes step of determining a clearance (Y) between the first shear web (112) and the second shear web (122); and determining a distance (X) to be maintained between the lower shell (110) and the upper shell (120) for avoiding collision between the shear webs (112,122) at the time of fixing the lower shell (110) and the upper shell (120) when the upper shell (120) is turned over the lower shell (110) for fixing; wherein the clearance (Y) between the first shear web (112) and the second shear web (122) while turning is restricted to be of formula (I): Y a X (I)
In an embodiment, the formula is applicable only when the upper shell (120) is turned over the lower shell (110) by utilizing hydraulic hinges.

In an embodiment, turning path (130) of the second shear web (122)is shown as dashed lines (Fig. 2B).
In an embodiment, first shear web (112) and second shear web (122) installed in the lower shell (110) and upper shell (120) respectively are supported by means of jigs (140) while placement of the shear webs (112,122) and curing of the adhesive, to bond the shear webs with the respective shells (Fig. 2A).
According to a preferred embodiment, the clearance 00 between the first shear web (112) and the second shear web (122) is 90 mi11 minimum.
According to an embodiment of the present invention bond between the second. shear web (122) and the upper shell (120) is strong enough to carry the second shear web (122) apparently throughout the closing procedure.
The present invention is advantageous in saving the cycle time as the cycle time is reduced to 50% and is easy in operation. Further. no sophisticated tool is required for assembling and there is no space constraint issue for adhesive application. There is no damage of shear webs due to hole making process, no extra support tool cost is incurred and no extra support tooi is required.
The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since, modifications of the disclosed embodiments incorporating the spirit and substance of tne invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the appended claims.

We Claim
1. A method for assembling a rotor blade of a wind turbine wherein the rotor
blade includes a lower shell and an upper shell, the method comprising the
steps of:
positioning the lower shell and the upper shell;
identifying a first fastening area on each shell;
fastening a first shear web at the first fastening area on an inner surface of the lower shell and a second shear web at the first fastening area on an inner surface of the upper shell;
and
fixing the lower shell and the upper shell thereby assembling the rotor blade.
2. The method as claimed in claim 1, wherein the shear webs are fastened to the shells of the rotor blade by applying adhesive and allowing curing.
3. The method as claimed in claim 1 or 2, wherein positioning and fastening first shear web and second shear web one after the other and curing of both the shear webs over the shells can be carried out simultaneously.
4. The method as claimed in one of claims 1 to 3, wherein the step of fixing of the lower shell and upper shell for assembling the rotor includes step of:
applying adhesive at extreme ends of the lower shell; and applying adhesive on top of the first shear web and at a second fastening area on the inner surface of the lower shell for fastening the first shear web to the upper shell and for fastening the second shear web to the lower shell.

5. The method as claimed in one of claims 1 to 3, wherein the step of fixing of
the lower shell and upper shell for assembling the rotor includes step of:
applying adhesive at extreme ends of the lower shell; and applying adhesive on top of the second shear web and at a second fastening area on the inner surface of the upper shell for fastening the second shear web to the lower shell and fastening the first shear web to the upper shell.
6. The method as claimed in one of claims 1 to 3, wherein the step of fixing of
the lower shell and upper shell for assembling the rotor includes step of:
applying adhesive at extreme ends of the lower shell; and applying adhesive at a second fastening area on the inner surface of the lower shell and at a second fastening area on the inner surface of the of the upper shell for fastening the second shear web to the lower shell and fastening the first shear web to the upper shell.
7. The method as claimed in one of claims 1 to 3, wherein the step of fixing of
the lower shell and upper shell for assembling the rotor includes step of:
applying adhesive at extreme ends of the lower shell; and
applying adhesive on top of the first shear web and on top of the second
shear web for fastening the second shear web to the lower shell and fastening
the first shear web to the upper shell.
8. The method as claimed in claim 1, wherein the step of fixing the lower shell
and upper shell is carried out by lowering the upper shell on top of the lower
shell with the help of crane.

9. The method as claimed in claim 1, wherein the step of fixing the lower shell
and upper shell by connecting the lower shell and upper shell at one end with
the help of swivel and turning the upper shell with the help of hydraulic hinges.
10. The method as claimed in claim 9, wherein the step of fixing of the lower
shell and upper shell for assembling the rotor includes step of:
determining a clearance (Y) between the first shear web and the second shear web;
determining a distance (X) to be maintained between the lower shell and the upper shell for avoiding collision between the shear webs at the time of fixing the lower shell and the upper shell when the upper shell is turned over the lower shell for fixing;
wherein the clearance (Y) between the first shear web and the second shear web while turning is restricted to be of formula (I),
YαX(l)
11. The method as claimed in claim 10, wherein the clearance is 90 mm
minimum.

12. A rotor blade of a wind turbine assembled by the method as claimed in one of preceding claims, the rotor blade comprising:
a lower shell and an upper shell to be fixed to each other;
at least two shear webs to be fastened on an inner surface of the lower shell and an inner surface of the upper shell.