Wind turbine components

Abstract

A method of making a wind turbine component comprises providing a mold (7), placing a fibrous pre-form (60) in the mold (70), admitting resin into the mold and curing the resin. The method further comprises heating (58) the fibrous pre-form before placing the pre-form in the mold.

Claims

1. A method of making a wind turbine component, the method comprising: providing a mould, the mould defining a half shell of a wind turbine blade; providing a fibrous pre-form, the fibrous pre-form comprising multiple layers of dry glass fibre fabric attached together; heating the fibrous pre-form outside of the mould to a heated state; placing the fibrous pre-form in the mould while in the heated state; admitting resin into the mould; and curing the resin.

2. The method of claim 1, further comprising: heating the fibrous pre-form to a first temperature before placing the fibrous pre-form in the mould, and admitting resin into the mould at a second temperature, wherein the first temperature is higher than the second temperature.

3. The method of claim 2, wherein the first temperature is between 30 C. and 80 C.

4. The method of claim 1, wherein heating the fibrous pre-form comprises arranging the fibrous pre-form in contact with one or more heating devices.

5. The method of claim 4, comprising arranging the fibrous pre-form over a support.

6. The method of claim 5, comprising arranging the or each heating device between the support and the fibrous pre-form.

7. The method of claim 5, comprising arranging an insulating layer over the fibrous pre-form.

8. The method of claim 4, wherein the or each heating device is a heating mat or heating blanket.

9. The method of claim 4, comprising heating a plurality of fibrous pre-forms together.

10. The method of claim 9, comprising stacking the plurality of fibrous pre-forms on a support.

11. The method of claim 10, comprising arranging a heating device and/or an insulating layer between the fibrous pre-forms in the stack.

12. The method of claim 1, comprising storing the fibrous pre-form in a heated state.

13. The method of claim 1, comprising making and heating the fibrous pre-form simultaneously.

14. The method of claim 13, comprising making the fibrous pre-form on a heated surface.

15. The method of claim 1, wherein the wind turbine component is a wind turbine blade.

16. The method of claim 1, wherein the multiple layers of dry glass fibre fabric are attached together by stitching or adhesive.

17. The method of claim 1, further comprising: heating the mould while the fibrous pre-form is placed in the mould.

18. A method of making a wind turbine rotor blade from a pair of half shells, the method comprising: providing a mould, the mould defining a half shell of the wind turbine blade; providing a support adjacent to the mould, the support including a heated surface supporting one or more fibrous pre-forms on the heated surface and an insulating layer over the one or more fibrous pre-forms, the or each fibrous pre-form comprising multiple layers of dry glass fibre fabric attached together; heating the one or more fibrous pre-forms on the support to a heated state; removing at least one of the one or more fibrous pre-forms from the support and placing the at least one fibrous pre-form in the mould while in the heated state; admitting resin into the mould; and curing the resin.

19. The method of claim 18, wherein the one or more fibrous pre-forms include a plurality of pre-forms arranged in a stack and being supported by the support, wherein each pre-form includes an insulating layer overlying the pre-form.

20. A method of making a wind turbine rotor blade from a pair of half shells, the method comprising: providing a mould, the mould defining a half shell of the wind turbine blade and having heaters for heating the mould; providing a support adjacent to the mould, the support including a heated surface supporting one or more fibrous pre-forms on the heated surface, the or each fibrous pre-form comprising multiple layers of dry glass fibre fabric attached together; heating the one or more fibrous pre-forms on the support to a first temperature; removing at least one of the one or more fibrous pre-forms from the support and placing the at least one fibrous pre-form in the mould while in a heated state; activating the heaters on the mould to maintain the at least one fibrous pre-form at or near the first temperature; admitting resin into the mould at a second temperature, wherein the first temperature is higher than the second temperature; and curing the resin.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1 and 2, which are respectively perspective and cross-sectional views of a wind turbine blade, have already been described above by way of background to the invention. In order that the invention might be more readily understood, reference will now be made, by way of example only, to the accompanying drawings, in which:

(2) FIG. 3 is a front view of a pre-form heating apparatus in use in heating a pre-form;

(3) FIGS. 4 to 9 illustrate in perspective view stages of a method of making a wind turbine blade according to an embodiment of the invention, using the pre-form heating apparatus of FIG. 3; and

(4) FIG. 10 is a front view of another pre-form heating apparatus in use in heating a plurality of pre-forms arranged in a stack.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(5) FIG. 3 illustrates a pre-form heating apparatus 50 for heating a pre-form 60 before the pre-form 60 is arranged in a mould 70 (not shown in FIG. 3, but visible in FIG. 4) for incorporation into a wind turbine component. In this example, the wind turbine component is a wind turbine blade, and the mould is a half mould 70 for moulding a half shell of the wind turbine blade.

(6) The pre-form heating apparatus 50 comprises a support 52, in the form of a flat surface 54 that is supported above the ground by legs 56. A heating device which in this example is in the form of a heating mat 58 is arranged on the flat surface 54 of the support 52. In use, a pre-form 60 is arranged on the heating mat 58, and an insulating blanket 62 covers the pre-form 60.

(7) In the embodiment illustrated, as shown in FIG. 4, the support 52 is arranged near the mould half 70.

(8) Referring now to FIGS. 5 to 9, to heat the pre-form 60, the heating mat 58 is arranged on the flat surface 54 of the support 52, as shown in FIG. 5. Next, and as shown in FIG. 6, the pre-form 60 is arranged in contact with the heater mat 58, such that the heater mat 58 is arranged between the support 52 and the pre-form 60. As shown in FIG. 7, the insulating blanket 62 is then laid over the pre-form 60 to complete the pre-form heating apparatus 50.

(9) The heating mat 58 is activated, and the pre-form 60 is heated up to a first temperature, which in this example is 40 C. A first temperature of approximately 40 C. is particularly advantageous because at 40 C. manual handling of the pre-form 60 is permitted by health-and-safety regulations with the use of appropriate safety equipment. As the pre-form 60 is heated, the insulating blanket 62 helps to reduce heat loss to the surroundings, thereby reducing the time required to heat the pre-form 60 up to the first temperature.

(10) As the pre-form 60 is heating up, the mould half 70 is prepared for the lay-up process. In particular the mould half 70 is heated, for example by heating elements embedded in the mould. Once the mould half 70 has been heated, early stages of the lay-up are carried out, and components are laid up on a mould surface 72 of the heated mould half 70. Eventually a stage of the lay-up process is reached where the heated mould-half is ready to receive the pre-heated pre-form 60.

(11) The time required to pre-heat the pre-form 60 depends on the thickness of the pre-form 60, and the power supplied by the heating mat 58. In some cases it may take several hours to pre-heat the pre-form 60. The pre-heating of the pre-form 60 is timed such that the pre-form 60 has already reached the first temperature when the heated mould-half 70 is ready to receive the pre-heated pre-form 60. To ensure that the pre-form 60 has reached the first temperature in time, the pre-form 60 may be stored in the pre-form heating apparatus 50 in a heated state until it is needed.

(12) In this way, as soon as the pre-form 60 is required, the pre-heated pre-form 60 is at the first temperature, and is ready to be transferred to the heated mould half 70 and laid up on the heated mould surface 72, as shown in FIG. 8. The transfer may be carried out manually by hand, using appropriate safety equipment, or the transfer may be partially- or fully-mechanised.

(13) Once the pre-heated pre-form 60 has been laid up on the heated mould surface 72, other components 80 of the blade are laid up on the heated mould surface 72, as shown in FIG. 9. The lay-up process then continues until all the components of the half shell have been laid up in the mould half 70.

(14) The other components 80 of the half shell are typically thinner than the pre-form 60, and so are quickly heated by the heated mould half 70 to a temperature that is at or near the first temperature. Meanwhile, the heated mould half 70 maintains the temperature of the pre-heated pre-form 60 at or near the first temperature.

(15) In this way, all of the components 60, 80 in the mould half 70 quickly reach a temperature that is at or near the first temperature, so that the infusion process can begin without the need to wait for the pre-forms 60 to heat up.

(16) With the pre-heated pre-forms 60 and the other components 80 in place in the mould half 70, the components 60, 80 are covered with an airtight bag to form an evacuation chamber encapsulating the components 60, 80. The chamber is evacuated using a vacuum pump, at which stage the chamber is ready for resin infusion.

(17) As the chamber is evacuated, a supply of liquid resin is heated to a second, infusing temperature. The second temperature is below the first temperature, and in this example is approximately 30 C. Once the chamber has been evacuated and the resin has been heated to the second temperature, the supply of heated resin is connected to the chamber. The heated resin is introduced into the chamber and infuses between the encapsulated components, including the pre-heated pre-form 60 and the other components 80.

(18) Because the pre-heated pre-form 60 and the other components 80 of the half shell are at or near the first temperature, which is higher than the temperature of the infusing resin, the resin maintains its temperature as it is infused. In this way, the fluidity of the resin, which is temperature-dependent, is maintained at the level required for fast and effective infusion. Furthermore, maintaining the temperature of the resin at the second temperature means that the resin can be heated more quickly to the curing temperature, which in this example is approximately 80 C.

(19) Thus, by pre-heating the pre-form 60, the cycle time for heating the components of the half shell is reduced, and the temperature of the infusing resin can be maintained, resulting in a faster infusion process, and a faster curing time. The time required for a manufacturing cycle is therefore significantly reduced.

(20) FIG. 10 illustrates an alternative embodiment of the pre-form heating apparatus 150. In this embodiment, the pre-form heating apparatus 150 supports and heats a plurality of pre-forms 60. The pre-forms 60 are arranged in a stack on the support 152, with a heating mat 158 arranged in contact with a lower surface of each pre-form 60, and an insulating blanket 162 laid over an upper surface of each pre-form 60. In this way, a heating mat 158 and an insulating blanket 162 is arranged between neighbouring pre-forms 60 in the stack. A protective, insulating case 164 is arranged over the entire stack of pre-forms 60, to protect the pre-forms from the surroundings, to help maintain the pre-forms at the first temperature, and also to protect personnel in the vicinity of the pre-form heating apparatus 150 from contact with the heated stack.

(21) In this way, a plurality of pre-heated pre-forms 60 can be stored in the pre-form heating apparatus 150 in a heated state, until the pre-forms 60 are required for lay-up in the mould half 70.

(22) Embodiments of the invention are also envisaged in which the pre-forms 60 are made on a heated support, or are otherwise made such that the pre-forms 60 are made and heated simultaneously. Once made, the pre-forms 60 may be stored on the same support where they continue heating up to the first temperature, or the pre-forms 60 are transferred to another heated support, such as the pre-form heating apparatus 50, 150 described above for continued heating.

(23) Still other embodiments are envisaged in which the individual layers of the pre-form 60 are heated separately before the individual layers are stitched together to make the pre-form 60.

(24) In the illustrated embodiments the pre-form heating apparatus is arranged next to the mould half. However, this need not necessarily be the case, and the pre-form heating apparatus may be arranged in any suitable location. If required, the pre-form heating apparatus may be transferred form a location away from the blade mould to a location near the blade mould. Alternatively, the pre-heated pre-forms may be removed from the pre-form heating apparatus and transferred to the mould half in an insulating apparatus or on a transportable heating apparatus, to prevent heat loss during transfer.

(25) Although in the embodiments described the first temperature is approximately 40 C. and the second temperature is approximately 30 C., this need not be the case, and the first and second temperatures may be any suitable temperatures. Whilst it may be advantageous to pre-heat the pre-forms to a temperature that is greater than the temperature of the resin used in the infusion process, this is not essential. For example, the pre-forms may be heated to the same temperature as the resin. In other embodiments, the pre-forms may be heated to a lower temperature than the resin before the pre-forms are placed in the mould, and the pre-forms may then undergo additional heating once placed in the mould to further elevate the temperature of the pre-forms.

(26) The present invention is therefore not limited to the exemplary embodiments described above and many other variations or modifications will be apparent to the skilled person without departing from the scope of the present invention as defined in the following claims.