Layer arrangement structure

Abstract

The present invention describes a ply arrangement (1) for use in a method of moulding a wind turbine rotor blade (2), the ply arrangement (1) comprising: a plurality of suspension preforms (10), each comprising a shaped body (10B) formed from a plurality of reinforcing fiber sheets (10L) bonded by a pre-activated binder (B), and a suspension portion (10H) for suspending the forming body (10B) from the upper edge of the mold (M2); and a plurality of holding means (11) provided at the tool machining surface (4), each holding means (11) being arranged to engage with a hanging portion (10H) of the hanging preform (10). The invention also describes a method of manufacturing a wind turbine rotor blade (2) using such a ply arrangement (1).

Description

BACKGROUND

[0001] Wind turbine rotor blades are generally manufactured as composites in a procedure involving laying up layers of reinforcing fibre material in a mould, injecting resin through the layers, and curing the injected resin lay-up. The reinforcing fibre material typically comprises relatively inexpensive glass fibres, while to increase the strength and stiffness in certain parts of the rotor blade, more expensive carbon fibre reinforced polymer (CFRP) or aramid fibre reinforced polymer can be deployed.

[0002] Long rotor blades for modern wind turbines can easily have a length of 80 m or more, reaching 5 m or more in width at the widest point along their span. Lay-ups for such long rotor blades can comprise many layers, each of which must be carefully and precisely laid up, as the structural performance of the rotor blade depends to a large extent on the type of reinforcing material and the number of layers used in the various regions of the lay-up. To simplify the lay-up procedure when manufacturing a wind turbine rotor blade, it is known to lay up a "preform" in the mould. A preform is a component made from several layers of fabric / textile reinforcing material, and can also comprise one or more layers of core material, such as balsa wood. The layers are cut to the desired size and shape in an initial stage, and are coated with a thermosetting or thermoplastic adhesive. After the layers are laid up into a stack, heat is applied to activate the adhesive, which softens and causes the adjacent layers to adhere. At this stage, the component can be shaped as needed, for example shaped as a curved part, to match the curvature in the region of the rotor blade where the component is to be deployed. After cooling, the adhesive hardens again, and the component retains the curved shape, as the layers are now adhered to each other. The shaped and hardened preform can be laid up in the rotor blade mould during the lay-up procedure, for example in any region that would otherwise require many steps to build up the desired number of reinforcing fibre layers. Generally speaking, the preform extends over only a small fraction of the width / length of the lay-up, and is a relatively small part. One problem with using preforms is that they are difficult to hold in place during the lay-up procedure. Any preform laid up on an inclined part of the mould can tend to slip and move to a lower position. Slippage is most likely to occur in curved regions, such as the rounded root portion, but can occur in any part of the rotor blade that has a significant curvature, for example at the leading edge. A preform that has slipped from its intended position can cause serious problems, as the actual lay-up no longer meets the specifications, and the structural performance of the rotor blade can be compromised. The problem of preform slippage can be remedied by applying a high-friction material to the surface of the preform, so that it is less likely to slip. However, this adds an additional step to the procedure, and is not entirely reliable. In any case, the weight of a preform with high-friction material on its underside can cause it to drag any underlying layers with it as gravity pulls it to a lower position in the mould.

[0003] It is therefore an object of the present invention to provide a solution to the above-mentioned problems.

[0004] This object is achieved by the layup arrangement as claimed and by the method of manufacturing a wind turbine rotor blade as claimed. SUMMARY

[0005] The layup arrangement described below is particularly suitable for use in a method of moulding a wind turbine rotor blade, but can of course also be deployed in the manufacture of any large composite object.

[0006] According to the invention, the layup arrangement comprises a number, i.e. one or more, of suspended preforms each having a shaped body formed of a plurality of sheets of reinforcing fibres held together by a pre-activated binder, and a suspension portion for suspending the shaped body from an upper edge of a mould. The layup arrangement further comprises a number of holding devices arranged on a tooling surface, each holding device being arranged to engage with the suspension portion of a suspended preform.

[0007] The tooling surface can be part of the mould or external to the mould, and should be understood to be arranged such that, when the suspension portion of a suspended preform is attached to a holding device, the shaped body of the suspended preform is effectively suspended from the upper edge of the mould. The suspension portion of a suspended preform can be an extension of the preform itself, or can be attached to the preform body, as will be explained below.

[0008] One advantage of the layup arrangement of the present invention is that it facilitates the inclusion of preforms that would otherwise slip and move from their intended position in the mould. The layup arrangement of the present invention thus provides an economical and straightforward way of incorporating any type of preform shape in a wind turbine rotor blade layup, while ensuring that the layup is performed according to specification.

[0009] The present invention also describes a way of manufacturing a wind turbine rotor blade using such a layup arrangement: According to the invention, the method of manufacturing a wind turbine rotor blade comprises the steps of providing a number of suspended preforms each comprising a shaped body formed of a plurality of sheets of reinforcing fibres bonded by a pre-activated binder, and a suspension portion for suspending the shaped body from an upper edge of a mould; and providing a number of holding devices at a tooling surface, each holding device being arranged to engage with the suspension portion of a suspended preform. The method continues with a phase of forming a layup in the mould. This is done by attaching the suspension portion of each suspended preform to a holding device and arranging the shaped body of the suspended preform at an appropriate position in the mould, and by arranging further layers of reinforcing material in the mould.

[0010] The location of each preform (and any reinforcing layer) can be defined in the layup specifications. One advantage of the method of the present invention is that curved preforms can be simply placed in their designated locations during the layup process, without requiring time-consuming measures to prevent preform slippage by a technician. Conversely, the step of placing the suspended preforms in the mold can be as simple as placing fiber sheets in the mold.

[0011] Particularly advantageous embodiments and features of the invention are given by way of the dependent claims, as disclosed in the following description. Features from different categories of claims may be combined, as appropriate, to provide further embodiments not described herein.

[0012] The terms “fiber-reinforced sheet,” “fiber sheet,” and simply “sheet” should be understood as synonyms and can be used interchangeably in this document.

[0013] Any number of suspension preforms can be arranged in the mold, at any suitable location within the mold. Suspension preforms can also be "stacked" to any suitable depth, meaning that after one suspension preform is placed in the mold, another can be placed on top of it. This significantly simplifies the layup for large wind turbine rotor blades.

[0014] In a particularly preferred embodiment of the invention, the forming body of the suspension preform is shaped for placement at a mold position corresponding to any of the following: the trailing edge of the rotor blade airfoil portion; the leading edge of the rotor blade airfoil portion; or the rotor blade root portion. Depending on its predetermined position in the layup, the preform shape is based on the specific rotor blade mold curvature at that position. A suspension preform intended for placement in a substantially circular root portion may be formed as an arc; a suspension preform intended for placement at the leading edge of the airfoil portion may have a more pronounced curvature; and a suspension preform intended for placement between the leading and trailing edges may have a correspondingly shallow curvature. Of course, the shape of the preform does not necessarily correspond to the mold shape at that position. In each case, the length of the suspension portion is selected to allow the preform body to be precisely placed at its predetermined position, wherein the suspension portion extends from the upper edge of the preform body to a retaining device disposed at a tooling surface.

[0015] The suspension portion can be implemented as one or more fiber sheets extending from the upper edge of the preform body. Providing a single suspension portion extending from the preform body may be sufficient. Of course, one or more additional sheets can extend from opposite edges of the preform body and can be incorporated into the rotor blade layup.

[0016] The suspension portion may be part of a fiber sheet extending above or below the stack forming the preform body. Alternatively, the suspension portion may be part of a fiber sheet extending around the stack.

[0017] The retaining device can be implemented in any suitable manner. For example, the retaining device may include hook and loop fasteners, suction components, mechanical clamps, electromagnetic devices, adhesives, etc. The tooling surface on which the retaining device is disposed may be the surface of a mold flange, an upward-facing surface surrounding the mold periphery, or the surface of a separate tooling element such as a scaffolding platform.

[0018] If pins are placed around the perimeter of the mold for the purpose of holding very long sheets in place (such long sheets can extend from one side of the mold to the other), these pins can also be used as holding devices for suspending preforms.

[0019] The layup arrangement structure of this invention can be used in different types of molding techniques. For example, in the "closed mold" method, rotor blade layup can be accomplished by: filling the lower mold half (e.g., suction-side mold) with a first layup or lower layup including a spars cap and a shear web; arranging a mandrel in the mold; and forming a second layup or upper layup on the mandrel. At this stage, any suspended portions can be separated from their holding devices and cut to the appropriate size (if necessary). The suspended portions of the preform can be incorporated into the upper layup. After the upper layup is completed, the upper mold half (e.g., pressure-side mold) is placed on the lower mold half. The mold is then closed and a vacuum is established to allow the resin infusion and curing steps to be performed.

[0020] In the alternative "open mold" method, the layup, infusion, and curing steps can be performed separately for the suction and pressure sides of the rotor blades. Layups are prepared in each half-mold. Prior to the vacuum bag forming step, any suspended portions can be separated from their holding devices and cut to the appropriate size (if necessary). After the vacuum bag setup is ready, a vacuum is established and the resin infusion and curing steps are performed. After demolding and completion steps, the cured rotor blade halves can then be bonded along their periphery.

[0021] Other objects and features of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. However, it is to be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Attached Figure Description

[0022] Figures 1-4 The various stages in the manufacturing of the suspended prefabricated component of the layup arrangement structure of the present invention are shown; Figure 5 Several types of such suspension prefabricated components are shown; Figure 6 An exemplary method for connecting the suspension portion to the prefabricated body is shown; Figure 7The diagram illustrates the stages during the installation of wind turbine rotor blades; Figures 8-10 Various embodiments of the layup arrangement structure of the present invention are shown; Figure 11 A wind turbine rotor blade manufactured using the method of the present invention is shown.

[0023] In the accompanying drawings, the same reference numerals denote the same objects throughout. The objects in the drawings are not necessarily drawn to scale. Detailed Implementation

[0024] Figures 1-4 The various stages of manufacturing of an exemplary embodiment of the suspended prefabricated component 10 for the layup arrangement structure of the present invention are shown. Figure 1 A stack S of fiber sheets 10L is shown. Each sheet 10L or layer is pre-cut to a desired shape and size, and the sheets 10L are arranged in a desired order to form the stack S. As explained above, the reinforcing fiber sheets can be woven or non-woven sheets made of any suitable reinforcing fibers or combinations of reinforcing fibers. As shown in the enlarged section, a thermosetting or thermoplastic adhesive B can be applied to one or both surfaces of each layer 10L, for example, by spraying droplets of a suitable epoxy paste or by spraying the adhesive B in powder form onto the layer 10L.

[0025] The stack S can have a simple shape (e.g., each cross-section is substantially rectangular) or a more complex shape (e.g., one or more sides of the stack are angled), as shown here. In this exemplary embodiment, the bottom layer of the stack S is longer than the other layers, thereby forming a hanging portion 10H at one side of the stack S. Of course, any layer in the stack can be a "long layer" such that the hanging portion can extend from any layer of the stack, such as... Figure 2 As shown in the image.

[0026] exist Figure 3 In this stage, the fabrication of the preform continues by shaping the stack S according to a desired curvature (e.g., the curvature at the leading edge of a wind turbine rotor blade airfoil). A suitable forming mold M10 can be used for this stage. Of course, the steps of constructing the stack S and shaping the stack S can be combined, i.e. Figure 1 and Figure 2 The steps can also be performed in the preform mold M10.

[0027] exist Figure 4In this process, the preform 10 is completed by performing vacuum-bagging on the mold M10, establishing a vacuum, and applying heat (exemplary heater 5 shown) to activate the adhesive B, which softens and causes the stacked adjacent sheets 10L to adhere to each other, thereby defining the formed body of the suspended preform. The suspended portion 10H remains unaffected by this bonding stage. After the activation process is complete, the suspended preform 10 is allowed to cool and is subsequently removed from the mold M10.

[0028] Figure 5 Various finished suspension prefabricated components 10 are shown to illustrate various shapes that can be incorporated into the layup of wind turbine rotor blades.

[0029] Instead of making the suspended portion an extension of the initial stacked S layer 10L, the suspended portion 10H can be attached to the molded body 10B by stitching or by adhesive bonding, as shown below. Figure 6 As shown in the image.

[0030] Figure 7 The illustration depicts stages during the laying of a wind turbine rotor blade. The accompanying drawing shows a perspective cross-section of the lower die M2 taken at a point along the airfoil section. The upper surface around the die is a tool-machined surface 4, along which upwardly projecting spikes 11 are spaced apart. Such spikes 11 are known to be used to "capture" and hold the upper edges of long fiber sheets laid in this die M2. A suspension preform 10 is placed in its corresponding position within the die M2. To keep the forming body 10B in place without slippage, the suspension preform 10 has a long suspension portion 10H that can be secured using the spikes 11.

[0031] For various reasons, the nails shown above may not be present on the tooling surface, and there are various other ways to implement the layup arrangement structure 1 of the present invention. Figures 8-10 Various embodiments of the layup arrangement structure of the present invention are shown to illustrate the proposed anti-slip concept: Figure 8 Other types of retaining devices 11 for securing the suspended preform in its position within the mold M2 are shown. Starting from the upper left, these retaining devices are: clamps 11 at the upper surface 4 of the mold; adhesive bonding 11 at the upper surface 4 of the mold; an electromagnet 11 having coils arranged in the body of the mold M2; a counterweight 11; and a suction arrangement structure 11 having channels formed in the body of the mold M2. Therefore, the layup arrangement structure 1 of the present invention is easily integrated into various molding techniques.

[0032] Figure 9A possible alternative is shown. Here, the suspended preform 10 is secured to the vertical surface 4 of the mold M2 by a suitable retaining device 11 (e.g., adhesive bonding, hook and loop fasteners, etc.).

[0033] Figure 10 Another possible alternative is shown, thus illustrating two other aspects of the method of the invention. Here, two suspension preforms 10 are arranged in the mold M2, one above the other. Furthermore, the suspension preforms 10 are arranged such that they extend above the upper surface of the mold M2. The suspension portion 10H uses a pin 11 extending from the upper surface 4 (or... Figure 8 (any other retaining device shown) to secure to the mold extension M ext The upper surface 4. This technology can be used to suspend a single suspension preform 10 (or any other number of suspension preforms 10) in the mold M2. Similarly, Figure 8 and Figure 9 The embodiment shown can be used to fix any number of suspension prefabricated parts 10.

[0034] The steps of molding rotor blades generally include: filling a lower mold (e.g., a suction-side mold) with a first layup comprising a spars cap and a shear web; arranging a mandrel in the mold; forming a second layup on the first layup; placing an upper mold (e.g., a pressure-side mold) on top of the lower mold; closing the mold; and subsequently performing resin infusion and curing steps. Instead of this “closed mold” method, the layup arrangement structure of the present invention can also be effectively used in an “open mold” method, in which rotor blade halves are formed and cured separately and subsequently bonded along their peripheries.

[0035] Figure 11 A wind turbine rotor blade manufactured using the method described above is shown. The layup for this rotor blade 2 can incorporate multiple suspension preforms 10, as shown by dashed lines. Curved suspension preforms 10 can be deployed in the root region, while “tighter” suspension preforms (with more pronounced curvature) can be used along the leading edge 2LE and trailing edge 2TE, and “flatter” suspension preforms 10 can be used along the pressure side and suction side of the rotor blade airfoil 2A.

[0036] Although the invention has been disclosed in the form of preferred embodiments and variations thereof, it will be understood that many additional modifications and variations can be made thereto without departing from the scope of the invention.

[0037] For clarity, it should be understood that the use of “a,” “an,” or “a” throughout this application does not exclude multiple, and “including” does not exclude other steps or elements.

Claims

1. A layup arrangement structure (1) in a method for molding wind turbine rotor blades (2), comprising: - Multiple suspended preforms (10), each comprising a molded body (10B) formed from multiple reinforcing fiber sheets (10L) bonded by a pre-activated adhesive (B), and a suspension portion (10H) for suspending the molded body (10B) from the upper edge of a mold (M2); and - A plurality of retaining devices (11) are provided on the tool processing surface (4), each retaining device (11) being arranged to engage with the suspension portion (10H) of the suspension preform (10).

2. The layer arrangement structure according to the preceding claim, wherein, The shaped body (10B) of the suspended preform (10) includes multiple reinforcing fiber sheets embedded in a pre-activated adhesive (B).

3. The ply arrangement structure according to any one of the preceding claims, wherein, The forming body (10B) of the suspension preform (10) is formed for placement at a mold position corresponding to: the trailing edge of the rotor blade (2TE); or the leading edge of the rotor blade (2LE); or the root portion of the rotor blade (2R).

4. The ply arrangement structure according to any one of the preceding claims, wherein, The suspension portion (10H) of the suspension preform (10) includes a fiber sheet (10L) extending from the upper edge (10E) of the molded body (10B).

5. The ply arrangement structure according to any one of the preceding claims, wherein, The suspension prefabricated component (10) comprises two or more suspension sections (10H).

6. The ply arrangement structure according to any one of the preceding claims, wherein, The suspension portion (10H) of the suspension preform (10) is part of the external reinforcing fiber sheet (10L) of the suspension preform (10).

7. The ply arrangement structure according to any one of the preceding claims, wherein, The retaining device (11) includes any of the following: an upwardly extending nail; a hook-and-loop fastener; an electromagnet arrangement; Counterweight; Fixture arrangement structure fasteners; Vacuum-laid structure; adhesive.

8. The ply arrangement structure according to any one of the preceding claims, wherein, The tooling surface is any of the following: the surface of the mold flange, the upper surface surrounding the mold perimeter, or a separate tooling element (M). ext ) surface.

9. A method for manufacturing a wind turbine rotor blade (2), the method comprising: - Provide multiple suspended preforms (10), each comprising a molded body (10B) formed from multiple reinforcing fiber sheets (10L) bonded by a pre-activated adhesive (B), and a suspension portion (10H) for suspending the molded body (10B) from the upper edge of the mold (M2). - A plurality of retaining devices (11) are provided at the tool-machined surface (4), each retaining device (11) being arranged to engage with the suspension portion (10H) of the suspension preform (10); and - The layup is formed in the mold (M2) in the following manner: - Attach the suspension portion (10H) of each suspension preform (10) to the retaining device (11), and arrange the forming body (10B) of the suspension preform (10) in the mold (M2); and The reinforcing material is arranged in the mold (M2).

10. The method according to the preceding claim, wherein, The layup is an underlay formed in the lower mold of a closed mold assembly.

11. The method according to the preceding claim, further comprising the subsequent step of forming an upper layer on the lower layer.

12. The method according to any one of the preceding claims, wherein, The suspended prefabricated component (10) is arranged to extend from the underlay to the overlay.

13. The method according to any one of the preceding claims, comprising the following subsequent steps: placing a second half-mold on the upper layer and joining the half-molds to prepare for resin infusion and curing.

14. A wind turbine rotor blade manufactured using the method according to any one of claims 9 to 13.

15. The wind turbine according to the preceding claim, comprising one or more suspension preforms (10) embedded along its trailing edge (2TE) and / or one or more suspension preforms (10) embedded along its leading edge (2LE) and / or one or more suspension preforms (10) embedded in its root portion (2R).

Images