Apparatus and method for use in wind blade assembly

Abstract

Apparatus for and a method of assembling a wind turbine blade are disclosed. The assembled wind blade comprises first 24 and second shells bonded together, with an internal structural 22 component spanning between their inner surfaces. The construction apparatus comprises a support structure 20 arranged to hold the internal component 22 alongside the first shell 24 and a rotation mechanism 36 arranged to rotate the support 20 such that the component 22 it holds is lifted, inverted, and lowered into the first shell where it can be bonded. The internal support structure 22 may be a web. The assembly apparatus may comprise a lowering mechanism 38, allowing adhesive to be applied to the shell beforehand. The method and apparatus allow for positioning before bonding, scalable blade sizes (using more support sections), faster web installation and greater automation.

Description

FIELD OF THE INVENTION The present invention relates to a method and apparatus for use in manufacturing a wind blade, for example a wind turbine blade for a wind turbine generator (WTG). The apparatus and method are for moving in internal structural component, such as a shear web, into position in a shell half of a blade being assembled. BACKGROUND OF THE INVENTION There are challenges in manufacturing large composite parts. These will be explained in the context of wind turbine blades, as an example, which can be many tens of metres long. Conventionally, wind turbine blades comprise an outer shell composed of two shell-halves that are joined together, one shell-half defining one surface of the blade, and the other shell-half defining a surface on the opposite side of the blade (in some contexts, each shell-half may alternatively be referred to as a “shell”, and this terminology will generally be used in the rest of this document). The two shell-halves may also be referred as the upper shell and lower shell (depending on the orientation in which the blade is fabricated), or the leeward shell and windward shell, or the pressure side (PS) shell and the suction side (SS) shell, based on the aerodynamic shape of the blade. The shell defines a relatively thin surface or skin of the blade. The interior of the blade is generally hollow, except for one or more longitudinal internal structural components that provide the blade with stiffness. To manufacture a blade, a shell mold is provided for each of the upper shell and lower shell. Each mold defines the shape of the exterior aerodynamic surface of the respective shell portion. Dry fiber materials are laid up in each mold; each mold is bagged; and liquid resin is infused into the fiber. The resin is cured to form each solid shell. Longitudinal internal structural components of one or more spar structures and / or web assembly or web assemblies are bonded into the lower shell. Adhesive is applied to the leading edge (LE) and trailing edge (TE) of the lower shell, as well as to the tops of the internal structural components. The upper shell mold containing the upper shell is then lifted and rotated into position above the lower shell mold containing the lower shell. The upper shell mold is lowered into position on the lower shell mold. Clamps around the edges of the molds align the mold flanges (and the shells within the molds) and apply a clamping force. The adhesive is cured to an appropriate level such that the two shells are bonded together to form the blade. The clamps are released, the upper mold is removed, and the blade is lifted from the lower mold, so that the blade can be taken to a finishing area. Conventionally, as explained above, a blade is constructed from two separate shell halves, with one or more shear webs positioned between the two halves to form an "I-beam" structure and provide the required mechanical strength. During the blade assembly process, the shear web(s) are transported to the blade halves using a large, product specific lifting device, known, for example, as a "Shear Web Positioner". This lifting device is used to ensure the location of the shear webs inside the blade is within the =2mm positioning tolerance because the position of the webs is critical to the performance of the blade. In more detail, the shear webs are each constructed in a respective mold in the same way as the shell halves. When construction is complete, the webs are demolded and transported to a floor station (or assembly station). The floor station comprises several sections. Each section is made up of one or two uprights with holding brackets and clamps to accept the leading and trailing edge webs. Some designs allow tilting of the uprights for easier loading of the webs. A number of these floor station sections are arranged in a line and their height and position set to exactly mimic the curvature of the blade shell half to which the webs will be bonded. The webs are then correctly positioned to the required tolerance in the floor station manually. Once correctly aligned in the floor station, the shear web positioning gantry is moved over the floor station and lowered onto alignment receivers positioned relative to the floor station ensuring the correct alignment of the webs is transferred to the gantry. The gantry is a very large steel truss structure moved with the use of two overhead cranes and fitted with a number of vacuum cup arms and clamps to grip and securely hold the webs during transport. Once the gantry vacuum cups and clamps are engaged with the webs, the floor station clamps are disengaged, and, as shown in Fig. I, the gantry 10 can be raised by the cranes (not shown) with the webs 12 and moved over the blade shell half 14 to which the web will be bonded. Once over the shell half 14, the gantry 10 is lowered onto alignment receivers / jacks (not shown) positioned around the shell mold as with the floor station. These receivers ensure the gantry 10 and webs 12 are in the correct position relative to the shell mold half 14. On some designs, clamps on the receivers / jacks clamp onto the gantry. The receivers / jacks then retract, lowering the gantry 10 and compressing the webs 12 into glue that has been pre-applied to the shell half 14, such that the gantry 10, webs 12, and shell half 14 are now in the position illustrated in Fig. 2. Once the glue is sufficiently cured, the gantry vacuum cups 16 and clamps 18 are disengaged from the webs 12 and the gantry 10 is removed to leave the bonded webs 12 and shell 14 as shown in Fig. 3. The other adjacent shell half can then be bonded on top of the webs 12 and shell half 14. Meanwhile, the gantry is stored either over the floor station (which hinders the loading of fresh webs into the floor station) on retractable legs fixed to the gantry, or on a specially designed storage rack, which also occupies more space. Because the purpose of the gantry is to maintain the correct positioning / shape of the web as it is transferred from the floor station to the shell half, the gantry cannot be allowed much deflection. This means that the gantry truss frame must be extremely rigid, leading to high quantities of steel being used and high gantry weights. This makes the gantry expensive, for example costing from half a million dollars to two million dollars or more, and containing over 30 tonnes of steel. As blade designs change, the gantry cannot be easily reused because it is custom made for a specific design, so it must be scrapped. Furthermore, as blades become longer, the gantry become less practical because it begins to deflect under its own weight. The present invention aims to alleviate, at least partially, some or any of the above problems. SUMMARY OF THE INVENTION According to one aspect of the invention there is provided a wind blade assembly apparatus for use in assembling a wind blade, the assembled blade comprising a first shell and a second shell bonded together, with an internal structural component spanning between an inner surface of the first shell and an inner surface of the second shell, the apparatus comprising: a support structure arranged to hold an internal structural component initially alongside a first shell; and a rotation mechanism arranged to rotate the support structure such that an internal structural component held by the support structure is lifted, inverted, and lowered into the first shell. Another aspect of the invention provides a method for use in manufacturing a wind turbine blade, the blade comprising a first shell and a second shell bonded together, with an internal structural component spanning between an inner surface of the first shell and an inner surface of the second shell, the method comprising: holding an internal structural component initially alongside a first shell using a support structure; and rotating the support structure such that an internal structural component held by the support structure is lifted, inverted, and lowered into the first shell. Further optional features are defined in the dependent claims. Embodiments of the invention remove the need for the entire gantry part of the traditional system and instead can rotate the entire “floor station” holding a shear web into the shell. This avoids the cost of the gantry, and saves space occupied by the gantry when not in use. No overhead cranes are required, freeing them up for other critical tasks. DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described, by way of non-limiting example, with reference to the accompanying drawings. The invention may further comprise, in any combination, any features of the embodiments which will now be described. Figures I to 3 illustrate three steps in the assembly of a wind blade using a convention apparatus and method not embodying the invention; Figure 4 is a view of an assembly apparatus, according to an embodiment of the invention, showing an internal structural component held by a support structure in an initial position; Figure 5 is another view of the apparatus of Fig. 4, end-on with respect to the internal structural component; and Figures 6 to 8 are a sequence of views of the operation of the apparatus of Fig. 4, lifting, inverting and lowering the internal structural component into a shell. In the drawings, like parts are indicated with like reference numerals, and, for conciseness, description thereof will not be repeated. DETAILED DESCRIPTION OF THE INVENTION Fig. 4 illustrates an apparatus, according to an embodiment of the invention, comprising a support structure 20 to hold an internal structural component 22 (in this example, a pair of shear webs) to be assembled into a first shell 24. The apparatus can advantageously, but not exclusively, be used for one stage in assembling long blades, such as at least 30m long, or at least 50m long, because it does not have the weight, cost or deflection problems of conventional gantry truss apparatus. The support structure 20 comprises a plurality of individual support sections 30 arrayed along the length of the internal structural component 22, as with a traditional floor station, to support the internal structural component in the correct alignment using holding brackets and / or vacuum clamps. Fig. 5 shows a preferred embodiment in which each support section 30 is mounted on an arm 32 via a tilt mechanism 34. The tilt mechanism 34 enables the support section 30 to be angled for ease of loading the internal structural component 22 before being brought upright (or to a desired angle), and the tilt mechanism 34 can enable the support section 30 to be folded flat when not in use. Each arm 32 is extendable / retractable (for example via a telescopic mechanism), again to enable the correct position / alignment to be achieved, and to reduce space for storage when not in use. Each arm 32 is connected to a rotation mechanism 36, such as a powered hinge, slewing drive, rack and pinion actuator (single-piston and / or multi-piston) and / or hydraulic rotary actuator; and each arm 32 is connected to a lift mechanism 38 (to raise / lower the arm 32, e.g. a jack). In the illustrated embodiment, the lift mechanism 38 is fixed to the floor, and the rotation mechanism 36 is connected between the lift mechanism 38 and the arm 32; in an alternative embodiment, the rotation mechanism can be fixed to the floor, and the lift mechanism can be connected between the rotation mechanism and the arm. The arms 32 can initially rest on or be supported by the floor, or can be above the floor (for ease of access) supported by the rotation mechanism 36 and lift mechanism 38. The individual rotation mechanisms 36 are positioned such that their rotation axes are aligned. Collectively, the individual rotation mechanisms 36, in combination, form an overall rotation mechanism comprising part of the apparatus. In other embodiments, additional structures can optionally interconnect the plurality of arms, or the arms can be integrated into a unified framework. The number of individual rotation mechanism 36 can be increased or reduced. All actuation (raise / lower, tilt, rotation and extend / retract) can be provided by mechanisms selected from any combination of hydraulic, electric or pneumatic. Operation of the apparatus will now be described. The internal structural component 22 (e.g. shear web) is demolded and moved to the support structure 20, for example using any simple lifting beam. The internal structural component 22 is aligned in the support structure 20 and then secured in position with either mechanical clamps, vacuum cups or a combination of both, to give the state shown in Fig. 4. The support structure 20 is then raised using the lift mechanisms 38 which extend out together, maintaining synchronization with one another. The rotation mechanisms 36 then rotate 180 degrees to lift, invert and lower the internal structural component(s) 22 into the shell half 24, as illustrated in Figs. 6 and 7 which show different stages of the rotation. The individual rotation mechanisms 36 are operated in a synchronous manner, for example being controlled by a programmable logic controller (PLC) to achieve synchronicity. In the case of the rotation mechanisms being hydraulic powered hinges, the hydraulic actuators are powered by variable speed pumps which in turn are controlled by the PLC. When fully rotated, the correct position of the internal structural compoent(s) 22 can be verified with settable hard stops on the mechanisms, adjustable setpoints in the control system or adjusted and verified by electronic sensors. Once the position is confirmed, the lift mechanisms 38 are retracted to lower the support structure 20 and force the internal structural components (e.g. web) into adhesive (such as a glue line) previously deposited on the shell 24, in the state shown in Fig. 8. Once the adhesive has cured sufficiently, the clamps and / or vacuum cups are disengaged and the support structure 20 returned to its starting position. The lift mechanisms 38 are not essential and could be omitted, and one could instead rely solely on a rotation mechanism. However, it is preferred to include lift mechanisms such that the final lowering of the internal structural components into a glue line is linear and vertical because it enables easier alignment positioning and better bonding. Because of the raise / lower and extend / retract features of the apparatus, the footprint can be greatly reduced. In one embodiment, the body of the system can be positioned under a walkway (that runs alongside the shell mold) with hatches to allow the system to be raised though the walkway when in operation. The levels of actuation mean that live adjustments can be made to the positioning of the blade structural component(s) just before bonding. This adjustment can be manual or done automatically in response to input from sensors. Further advantages of embodiments can optionally include: • The apparatus can be used for longer blades simply by adding more support sections and rotation mechanisms, so the system is scalable as blades increase in size. • Alternatively the apparatus can be recycled for use on new production lines, because it is not as product-specific as the conventional gantry. • Faster web installation times can be achieved. • Fewer operators are required. • Greater automation can lead to less operator training and better repeatability. • Live adjustment means less scrappages and repairs. It is emphasised that the described and illustrated assembly apparatus and method is merely one specific example; the invention can be practiced in numerous different ways within the scope as defined by the claims. For example, the internal structural component is illustrated as a pair of shear webs, but it can be a single web or more than two webs, or other comparable internal structural components or component. Although the above description has specifically mentioned manufacturing a wind turbine blade, the invention can also be applied in other embodiments to assembling blade structures such as for wind assisted propulsion of sea transportation vessels. One or more of these blades can typically be vertically mounted on top of the vessel, and is rotatable about the vertical axis. The vessel can be, for example, a cargo container, oil / gas tanker, or grain tanker. The aerodynamic blade or blades utilises wind assistance to augment the conventional propulsion of the vessel, thereby reducing fuel costs and emissions. In this context, a blade may also be called a wing or a sail, but the term ‘blade’ is used herein to encompass these alternative terms. Thus every aspect of the present description and claims can be read as disclosing such methods, apparatus and blades by replacing the term “wind turbine” by “shipping vessel”. The term ‘wind blade’ is used herein as a generic term to encompass a ‘wind turbine blade’ and a shipping wing or sail.

Claims

1. A wind blade assembly apparatus for use in assembling a wind blade, the assembled blade comprising a first shell and a second shell bonded together, with an internal structural component spanning between an inner surface of the first shell and an inner surface of the second shell, the apparatus comprising:a support structure arranged to hold an internal structural component initially alongside a first shell; anda rotation mechanism arranged to rotate the support structure such that an internal structural component held by the support structure is lifted, inverted, and lowered into the first shell.

2. An apparatus according to claim 1, further comprising a lift mechanism arranged to raise and lower the support structure.

3. An apparatus according to claim 2, wherein the operation of the lift mechanism is independent of the rotation mechanism.

4. An apparatus according to any preceding claim, wherein the rotation mechanism comprises a plurality of individual rotation mechanisms each comprising at least one of a powered hinge, slewing drive, rack and pinion actuator, hydraulic rotary actuator.

5. An apparatus according to any preceding claim, wherein the support structure and rotation mechanism comprise a plurality of individual support sections and individual rotation mechanisms arrayed along the length of an internal structural component to be assembled.

6. An apparatus according to any preceding claim, wherein the support structure further comprises at least one extendable arm arranged to move support sections, for engaging an internal structural component to be assembled, closer to and further from the rotation mechanism.

7. An apparatus according to any preceding claim, wherein the internal structural component comprises at least one shear web.

8. An apparatus according to any preceding claim, arranged for use in assembling a wind blade, wherein the length of the blade is at least 30 m, preferably at least 50 m.

9. A method for use in manufacturing a wind turbine blade, the blade comprising a first shell and a second shell bonded together, with an internal structural component spanning between an inner surface of the first shell and an inner surface of the second shell, the method comprising:holding an internal structural component initially alongside a first shell using a support structure; androtating the support structure such that an internal structural component held by the support structure is lifted, inverted, and lowered into the first shell.

10. A method according to claim 9, further comprising operating a lift mechanism to lower the support structure to force the internal structural component into adhesive previously deposited on the first shell.

11. A method according to claim 9 or 10, wherein the internal structural component comprises at least one shear web.

12. A method according to claim 9, 10 or 11, used in assembling a wind blade, wherein the length of the blade is at least 30 m, preferably at least 50 m.10

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