Patent Description:
Wind turbines with wind turbine rotor blades are widely known from the prior art and are used to convert wind energy into electrical energy. Rotor blades of wind turbines typically have an outer aerodynamic shell formed by two rigidly connected rotor blade half-shells. The rotor blade half-shells, and thus the rotor blades, are made of one or more composite materials or composite laminates. One or more shear webs are provided within the rotor blades to increase a stiffness of the rotor blade to withstand wind loads, which are often high during operation. Typically, these shear webs are connected to the rotor blade half-shells within the rotor blade via adhesive bonds.

In general a wind turbine rotor blade is made up of an aerodynamic external surface, with a progressively decreasing cross-sectional area in a spanwise direction from the blade root towards its tip and an internal, load-carrying structure which needs to resist both flapwise and edgewise loading. The external, aerodynamic surface is usually configured as a blade shell, generated and defined by a mould. Shell moulds are usually configured as two complementary mould "halves", with one half generating a blade suction (or leeward) side shell and the other half generating a blade pressure (or windward) side shell. The internal, load carrying structure inside the blade may generally extend from the blade root to blade tip and may often be manufactured separately from the shell e.g. in the form of an elongate internal spar or shear web. Wind turbine rotor blades known in the art are typically made from reinforced polymer resin type composite materials, with reinforcing materials including or combining one or more materials such as glass-fibre, wood, carbon fibres or certain metallic elements such as meshes.

The rotor blades are typically manufactured by moulding two rotor blade half-shells in two co-operating mould structures. In a known assembly process, the lower half-shell of the rotor blade is first provided in an upwardly open mould (i.e. a mould for forming and building the lower shell) or on a suitable frame so that its inner side faces upward. Adhesive is applied to the lower shell at the junction between the lower shell and the shear web(s). Each shear web is then lowered onto the lower half-shell at the desired position using a suitable lifting device until it rests on the lower shell. Afterwards, the adhesive bond is then cured, in particular by applying heat to the joint. Next, adhesive is then applied to the bonding area between the half-shells and to the bonding area between the shear web(s) and the top half-shell, and the top half-shell is placed on the shear web(s) and the bottom half-shell, usually by turning one mould half over onto the other. The half-shell and the shear web(s) are cured and thus adhesively bonded together.

For example, to ensure that the half-shells are pressed firmly together while the adhesive is hardening, pressure may be applied to the moulds, either by gravity acting on the mass of the top mould half structure or, more preferably, by pressing the upper mould down onto the bottom mould.

Another process known from the state of the art is the so-called one-shot-bonding process. In this process, the bond line between the first half-shell and the shear web is not completely cured at the time, when the second half-shell is lowered onto the first half-shell for bonding them together. It cures together with the other bond lines after closing the both shell moulds. The process is time-saving, but there is a need for an additional support of the shear web during the closing of the shell mould due to the uncured bondline. Fixtures are needed to prevent the shear web from tipping over and to eliminate shear web movement that could occur during shell bonding. Usually, stabilizers in form of rods are used, which are arranged between the shear web and the inner surface of the blade shell. As an alternative solution <CIT> suggests to use small positioning jigs which can be handled without a lifting equipment. The positioning jigs are located along the length of the shear web and supported on the mould flange. They have to be removed just before the mould is closing.

<CIT> discloses a method of making a wind turbine blade comprising first and second half shells and a shear web adhesively bonded between opposed inner surfaces of the half shells.

One task underlying the present invention is to provide a concept for manufacturing a wind turbine rotor blade, which enables a reliable production and contributes to reducing a necessary production time.

According to a first aspect a method for producing a wind turbine rotor blade for a wind turbine is disclosed. The wind turbine rotor blade being made of a rotor blade shell comprising a first half-shell, a second half-shell and a shear web, the shear web being arranged between the rotor blade half-shells running in the longitudinal direction of the wind turbine rotor blade.

The inventive method uses a shear web holding device to fix the shear web (or two or more shear webs, e.g. a main shear web and an auxiliary shear web) in the root area of the wind turbine blade. The fixture is designed to stabilize and hold the shear web(s) in position until the second half-shell is placed onto the first half-shell und the half-shells are firmly bonded together. The shear web holding has the advantageous effect that it isn't into contact neither with the inner surface of the rotor blade shell nor with the longitudinal flanges of the mould. The shear web holding device according to the invention provides a freely accessible working space along the shear web flange. It is stable supported at the mould, whereby the location at the mould end region allows a closing of the mould without removing the shear web holding device before.

As already indicated in the introductory part, for producing the wind turbine blade, providing the first half-shell means that the first half-shell is moulded initially in the mould tool, e.g. a first mould tool. The second half-shell is moulded separately, e.g. in a second mould tool.

The formed rotor blade shell defines a chordwise extent between a trailing edge and a leading edge thereof, and a spanwise extent between a root region and a tip thereof.

The shear web holding device (fixture) is a holding structure that is designed to hold and fix the shear web in position. In particular, the shear web holding device is arranged at the root end area of the wind turbine blade. The shear web holding device is made of a stiff and robust construction or structure. For example, the shear web holding device consists of one or more portions, that are fixed to the shear web and which are connected at least partially to the mould tool. The shear web holding device is connected to the mould tool itself to transfer and dissipate weight and/or tilting forces/moments.

The shear web holding device is suitably formed and constructed to hold the entire shear web in position, so that no further fixtures (shear web holding devices) are necessary along the length of wind turbine rotor blade. In particular, by arranging the shear web holding device at the root end area of the blade or the mould tool respectively, the tool can be left in the rotor blade shell until both half-shells are finally bonded together by adhesive, i.e. until curing the adhesive bonding has been finish. Afterwards, the shear web holding device can be removed from the wind turbine blade easily. In contrast, holding devices which are arranged along the length of the rotor blade, e.g. in the middle or at the tip side region, would necessarily be removed prior to placing the second half-shell onto the first, if such holding devices are fixed to the mould tool itself. Otherwise, holding devices which are placed inside the blade (not fixed to the mould tool) would difficult to be removed from the rotor blade anymore or would require space and hinder workers to work inside the blade during the bonding process. The described shear web holding device utilizes the available installation space, e.g. at the root end region, in such a way that workers in this area are not hindered by it.

According to an embodiment, the method comprises:.

This contributes to the above mentioned functions and advantages.

According to an embodiment, providing the shear web holding device comprises that the shear web holding device is fixed to the shear web and to the mould tool at a mould end region, the mould end region being associated with the root end of the wind turbine rotor blade. In other words, the shear web holding device extends from the shear web to the mould tool. In particular, the shear web holding device extends along the shear web in spanwise direction or diagonally from the shear web towards the mould end region. Thus, the shear web holding device does not extend in an exactly chordwise direction, i.e. orthogonal to a longitudinal direction of the wind turbine blade. This contributes to the above mentioned functions and advantages.

The mould end region is the end region of the mould tool that is associated to the root end of the wind turbine blade.

According to an embodiment, the shear web holding device is fixed at the root end of the shear web and extends from the shear web towards the mould end region.

According to an embodiment, the shear web holding device comprises two arms, the arms being fixed at the shear web and extending towards the mould end region, wherein at least one arm is fixed at the mould tool at the mould end region. Thus, a triangle of forces can be realized by the legs or arms.

According to an embodiment, one arm diagonally extends from the shear web towards the mould end region. In other words, the one arm extends in a direction that has two directional components, namely a longitudinal and a transversal direction component.

According to an embodiment, one arm is fixed at the shear web and extends in spanwise direction in parallel to the longitudinal direction of the shear web towards the mould end region.

According to an embodiment, one arm is fixed at a traversal bar, the traversal bar being firmly secured to the mould tool at the mould end.

According to an embodiment, one arm is fixed to a support point, which is firmly secured to the mould tool. This support point is located at a flange at the mould end region in a three-, six- or nine-o-clock- position.

According to an embodiment, both arms extend from the shear web at a predetermined angle to each other. they might extend diagonally from the shear web.

According to an embodiment, both arms are fixed at a traversal bar, the traversal bar being firmly secured to the mould tool at the mould end region.

The above embodiments contribute to the mentioned functions, effects and advantages. Optionally, two or more arms can be provided. The shear web holding is firmly fixed to the shear web at one or more fixing points. For example, the shear web can comprise means for attaching the shear web holding device.

According to a second aspect a shear web holding device is disclosed for producing a wind turbine rotor blade for a wind turbine according to a method of any of the above embodiments and description. The shear web holding device is configured:.

The shear web holding device essentially enables the above mentioned functions, effects and advantages. The above described features and embodiments with regard to the first aspect, in particular related to the shear web holding device, similarly apply to the described shear web holding device.

Further advantages, features and functions are given in the following exemplary embodiments of the invention, which are explained in connection with the figures. Identical, similar or similarly acting elements are provided with the same reference signs in the figures. Not necessarily all shown and describes elements are provided with reference signs for sake of clarity and visibility.

<FIG> shows a schematic view of a wind turbine <NUM>, which comprises a tower <NUM>. The tower <NUM> is fixed to the ground by means of a foundation <NUM>. At one end of the tower <NUM> opposite to the ground a nacelle <NUM> is rotatably mounted. The nacelle <NUM>, for example, comprises a generator which is coupled to a rotor <NUM> via a rotor shaft (not shown). The rotor <NUM> comprises one or more (wind turbine) rotor blades <NUM>, which are arranged on a rotor hub <NUM>.

During operation, the rotor <NUM> is set in rotation by an air flow, for example wind. This rotational movement is transmitted to the generator via the rotor shaft and, if necessary, a gearbox. The generator converts the mechanical energy of the rotor <NUM> into electrical energy.

<FIG> shows an exemplary wind turbine rotor blade <NUM>. The rotor blade <NUM> has the shape of a conventional rotor blade and has a rotor blade root area <NUM> facing the rotor hub <NUM>. The rotor blade root area <NUM> typically has an essentially circular cross-section. The rotor blade root area <NUM> is followed by a transition area <NUM> and a profile area <NUM> of rotor blade <NUM>. The rotor blade <NUM> has a pressure side <NUM> and an opposite suction side <NUM> with respect to a longitudinal extension direction <NUM> (also main extension direction). The rotor blade <NUM> is essentially hollow inside.

In the rotor blade root area <NUM> a rotor blade root end <NUM> with a flange connection <NUM> is provided, by means of which the rotor blade <NUM> can be mechanically connected to a pitch bearing or an extender.

The wind turbine rotor blade <NUM> is made of a first half-shell <NUM> and a second half-shell <NUM> and comprises at least one shear web inside, as described in the general part of this description. In the following, a method according to the invention for producing such rotor blade is detailed.

It is referred to <FIG>, which show cross sections of a production stage as well as a flow chart of the production method.

In a first step S1 a first half-shell <NUM> of the rotor blade <NUM> is provided in a mould tool <NUM>. The first half-shell <NUM> is already initially moulded in the mould tool <NUM>. The shear web <NUM> comprises an "I"-profile.

In a next step S2, a shear web <NUM> is placed into the first half-shell <NUM>, wherein adhesive (not shown) is provided on the first half-shell <NUM> and/or the shear web <NUM> in a respective junction area <NUM>. The shear web <NUM> runs from the root side to the tip side region of the rotor blade <NUM>.

In a next step S3, a shear web holding device <NUM> is provided at the root area <NUM> of the first half-shell <NUM> in order to securely hold the shear web <NUM> in position.

The shear web holding device <NUM> is a stiffening structure or a support structure that firmly holds the shear web in position. The shear web holding device <NUM> compensates any forces coming from moments (e.g. by tilting, moving of the shear web <NUM>) and partly forces coming from a weight of the shear web <NUM>. This is necessary for subsequent steps and in particular, since the adhesive is not cured at this stage of the production and thus not firm adhesive bonding between the first half-shell <NUM> and the shear web <NUM> is established for now. Additionally spacer elements can be provided between the shear web flange and the inner surface of the rotor blade shell.

The shear web holding device <NUM> is made of metal components, e.g. arms or legs and firm mechanical connections. In the shown embodiment of <FIG>, the shear web holding device <NUM> comprises a first arm <NUM> and a second arm <NUM>. Both arms <NUM> and <NUM> are firmly mounted to the shear web <NUM> at the root end of the shear web <NUM> (e.g. at the root end <NUM> of the blade <NUM>) or nearby. Both arms <NUM>, <NUM> diagonally extend from the shear web <NUM> along the longitudinal direction <NUM> towards a mould end region <NUM> of the mould tool <NUM>. At the mould end region <NUM>, the arms <NUM>, <NUM> are firmly connected to a traversal bar <NUM>, which is mounted at the end side, e.g. an flange <NUM>, of the mould tool <NUM>. The arms <NUM>, <NUM> are arranged at a certain angle α to each other, e.g. in a range of <NUM>° to <NUM>°. Thus, a very stiff construction is provided at the root end region of the blade <NUM> in order to hold the whole shear web <NUM> in place. Further, the shear web holding device <NUM> extends outwards from the root end region <NUM> towards the mould end region <NUM>.

In a next step S4 the second half-shell <NUM> (see dotted lines in <FIG>) is placed on the first half-shell <NUM> to essentially form the entire rotor blade shell <NUM>. For example prior to placing the second half-shell <NUM>, adhesive (not shown) is provided on the first half-shell <NUM> and/or the second half-shell <NUM> in a respective junction area <NUM>, and adhesive (not shown) is provided on the second half-shell <NUM> and/or the shear web <NUM> in a respective junction area <NUM>.

In a next step S5 the first and second half-shells <NUM>, <NUM> are adhesively bonded to each other and to the shear web <NUM> to finally form the rotor blade shell <NUM>, wherein the adhesive is cured, in particular by applying heat to the respective junction areas.

In a next step S6, the shear web holding device <NUM> is removed from the shear web <NUM> and the mould <NUM> after the curing process is finished or sufficiently finished.

Essentially, the shear web holding device <NUM> does not extend in an exactly chordwise direction (from leading to trailing edge). Further, the shear web holding device <NUM> remains installed to hold the shear web <NUM> until the curing process for the half-shells <NUM>, <NUM> is done.

<FIG> as well as <FIG> show further embodiments of the invention with regard to the shear web holding device. The above described method is similarly applicable.

The shear web holding devices <NUM> of these embodiments comprise the same features, except for the following differences mentioned. Therefore, not all features and reference signs are explained for sake of intelligibility.

With regard to <FIG>, the shear web holding device <NUM> comprises two arms <NUM>, <NUM>, wherein one arm <NUM> diagonally extends from the shear web <NUM> and is fixed to the traversal bar <NUM>. The other arm <NUM> extends in parallel to the longitudinal direction <NUM> of the rotor blade <NUM> (or the shear web <NUM> respectively) to a support point <NUM> in a six-o'clock-position at the flange <NUM> of the mould tool <NUM>. In particular, the other arm <NUM> is fixed at the mould end region <NUM>.

Claim 1:
Method for producing a wind turbine rotor blade (<NUM>) for a wind turbine (<NUM>), the wind turbine rotor blade (<NUM>) having a rotor blade shell (<NUM>) made of a first half-shell (<NUM>) and a second half-shell (<NUM>), wherein a shear web (<NUM>) is arranged in the shell running in the longitudinal direction (<NUM>) of the wind turbine rotor blade (<NUM>), having the following steps:
- providing the first half-shell (<NUM>) in a mould tool (<NUM>),
- placing the shear web (<NUM>) into the first half-shell (<NUM>),
- providing a shear web holding device (<NUM>) in a root area (<NUM>) of the first half-shell (<NUM>) in order to securely hold the shear web (<NUM>) in position, wherein the shear web holding device (<NUM>) is fixed to the shear web (<NUM>) and to the mould tool (<NUM>) at a mould end region (<NUM>), the mould end region (<NUM>) being associated with a root end (<NUM>) of the wind turbine rotor blade (<NUM>),
- placing the second half-shell (<NUM>) on the first half-shell (<NUM>),
- adhesive bonding of the first and second half-shells (<NUM>, <NUM>) to each other and to the shear web (<NUM>) to form the rotor blade shell (<NUM>) of the wind turbine rotor blade (<NUM>),
characterized by
- removing the shear web holding device (<NUM>) after the step of adhesive bonding.