METHOD FOR FABRICATING A MEMBER IN A RESIN-INFUSION-BASED CASTING PROCESS AND WIND TURBINE BLADE

Abstract

A method for fabricating a member in a resin-infusion-based casting process, in which at least one component forming the member is infused with a resin, including the steps: Providing a mold, the at least one component, the resin, at least one measurement device and at least one sensing device, wherein the sensing device has at least one property which changes measurably with temperature and/or when the sensing device comes into contact with the resin, attaching the at least one sensing device to an inner surface of the mold and/or to the component, arranging the component inside the mold, providing the resin to at least one inlet of the mold, and wirelessly measuring and evaluating the property of the sensing device with the measurement device for monitoring a temperature and/or a distribution of the resin in the mold and/or in the component, is provided.

Claims

1. A method for fabricating a member in a resin-infusion-based casting process, in which at least one component forming the member is infused with a resin, the method comprising: providing a mold, the at least one component, the resin, at least one measurement device and at least one sensing device, wherein the at least one sensing device has at least one property which changes measurably with temperature and/or when the at least one sensing device comes into contact with the resin; attaching the at least one sensing device to an inner surface of the mold and/or to the at least one component; arranging the at least one component inside the mold; providing the resin to at least one inlet of the mold; and wirelessly measuring and evaluating the at least one property of the at least one sensing device with the at least one measurement device for monitoring a temperature and/or a distribution of the resin in the mold and/or in the at least one component.

2. The method according to claim 1, wherein a plurality of sensing devices is arranged at different locations at the mold and/or at the at least one component.

3. The method according to claim 1, wherein after arranging the component in the mold, at least one further component and/or a supporting element is arranged on the component, wherein at least one further sensing device is attached to the at least one further component and/or to the supporting element opposite to the at least one sensing device or to at least one of the sensing devices attached to the mold and/or the at least one component.

4. The method according to claim 2, wherein the at least one measurement device is arranged to an outer surface of the mold opposite to the at least one sensing device or to at least one of the plurality of sensing devices, and/or that at least one hand-held device is used as measurement device.

5. The method according to claim 1, wherein the at least one sensing device is passively powered by energy provided by the at least one measurement device in a form of an electromagnetic field.

6. The method according to claim 1, wherein a radio frequency identification element is used as the at least one sensing device and that a radio frequency identification reader is used as the at least one measurement device.

7. The method according to claim 6, wherein a radio frequency impedance of the radio frequency identification element of an antenna of the radio frequency identification element, is used as property of the radio frequency identification element.

8. The method according to claim 1, wherein the at least one sensing device comprises a temperature measurement unit, which determines a temperature information corresponding to a temperature of the at least one sensing device, an identification unit, which provides an identification information specific to the at least one sensing device, a pressure measurement unit, which determines a pressure information corresponding to a pressure acting on the at least one sensing device, and/or a capacity measurement unit, which determines a capacitance information corresponding to an electrical capacitance of a vicinity of the at least one sensing device, wherein the at least one measurement device reads the temperature information, the identification information, the pressure information and/or the capacitance information from the at least one sensing device.

9. The method according to claim 1, wherein the at least one sensing device comprises a flexible and/or adhesive attachment portion, further wherein the attachment portion is used to attach the at least one sensing device to the inner surface of the mold and/or to the component.

10. The method according to claim 1, wherein the at least one measurement device is connected to a computing device, the computing device controls a heater of the mold in dependence of a temperature measured using the at least one sensing device and/or determines a resin distribution information describing the resin distribution in the mold and/or in the at least one component, and/or wherein the computing device controls at least one valve of a further inlet of the mold used for providing resin to the mold.

11. The method according to claim 1, wherein the mold comprises at least two parts completely enclosing an interior of the mold.

12. The method according to claim 11, wherein a vacuum is applied at least to the interior of the mold during provision of the resin.

13. The method according to claim 1, wherein a glass fiber mat is used as component and/or as further component and/or that a core component is arranged in between component and the further component, wherein the core component is balsa wood.

14. The method according to claim 1, wherein the member is a wind turbine blade.

15. A turbine blade fabricated according to the method of claim 1.

Description

BRIEF DESCRIPTION

[0045] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0046] FIG. 1 depicts a cut view of a mold illustrating a step of an embodiment of a method according to the present invention;

[0047] FIG. 2 depicts a cut view of a mold illustrating a step of an embodiment of a method according to the present invention;

[0048] FIG. 3 depicts a cut view of a mold illustrating a step of an embodiment of a method according to the present invention;

[0049] FIG. 4 depicts a cut view of a mold illustrating a step of an embodiment of a method according to the present invention;

[0050] FIG. 5 depicts a cut view of a mold illustrating a step of an embodiment of a method according to the present invention;

[0051] FIG. 6 depicts a cut view of a mold illustrating a step of an embodiment of a method according to the present invention;

[0052] FIG. 7 depicts a cut view of a mold illustrating a step of an embodiment of a method according to the present invention;

[0053] FIG. 8 depicts a perspective view of the mold; and

[0054] FIG. 9 depicts a wind turbine blade according to the present invention.

DETAILED DESCRIPTION

[0055] In FIGS. 1-7, different steps of an embodiment of a method according to the present invention are shown. In FIG. 1, a mold 1 provided for fabricating a member, for instance a wind turbine blade, in a resin-infusion-based casting process is shown. The mold 1 is an enclosed mold comprising at least two parts completely enclosing an interior 2 of the mold 1. In a first step of the method according to the present invention, a lower part 3 of the mold 1 is provided. To an inner surface 6 of the mold 1, two sensing devices 4 are attached. Opposing to each of the sensing devices 4, on an outer surface of the mold 1, a measurement device 5 is arranged.

[0056] The sensing devices 4 are radio frequency identification (RFID) elements, which are positioned at different locations inside the mold 1 for monitoring a temperature and/or a resin infusion into the mold. The sensing devices 4 comprise a property which changes measurably with temperature and/or when the sensing device 4 comes into contact with the resin provided in the interior 2 of the mold 1. The RFID elements used as sensing devices 4 each comprise an antenna, wherein a radio frequency impedance of the radio frequency identification element changes with temperature and/or when the sensing device 4 comes into contact with the resin.

[0057] For wirelessly measuring the changing property of the sensing devices 4, the measurement devices 5 are radio frequency identification readers (RFID readers), which can read out the at least one property of the sensing devices 4 that changes with temperature and/or upon contact of the sensing device 4 with the resin. A change of a radio frequency impedance of the RFID element can for instance be detected by the measurement device 5 to quantify an adaptive RF impedance setting used to match an antenna of the sensing device 4 to the measurement device 5.

[0058] The sensing devices 4 are able to operate in a temperature range between at least 0° C. and 90° C., between 0° C. and 150° C. and therefore within a temperature range of resin during infusion and/or during a subsequent curing step. The measurement devices 5 mounted on the outer surface of mold 1 are designed to withstand temperatures reached during a curing process of the resin, for instance temperatures between 0° C. to 90° C.

[0059] Each sensing device 4 comprises a flexible and/or adhesive attachment portion, which is provided by a flexible substrate with an adhesive surface, wherein the attachment portion is used to attach the sensing device 4 to the inner surface of the mold 1 and/or to a component 7 placed inside the mold 1. A sensing device 4 provided as a RFID element comprise a flexible circuit board, on which a sensor and an antenna of the RFID element are realized. For instance, RFID elements with a sticker tag type structure can be used. The attachment portion, or the substrate, respectively, comprise a thickness of 0.1 mm to 5 mm, in particular of 1.5 mm. The length and/or the width of the attachment portion, or the substrate, respectively is between 10 mm and 200 mm, in particular 150 mm.

[0060] In FIG. 2, to the inner surface 6 of the mold 1, at least one component 7 is arranged. The component 7 is for instance a glass fiber mat with a thickness of 20 mm to 30 mm, which is soaked by the resin in the casting process. On top of the component 7 at least one core component 8, which may not be infused by the resin during the process, is placed. The core component 8 can for instance be made of a polyethylene terephthalate (PET) foam or of balsa wood. The core component 8 may have for instance a thickness between 15 mm to 100 mm. On top of the core component 8, a further component 9, which is for instance a glass fiber mat according to the component 7, is arranged. In the fabrication process, as a member consisting of the at least one component 7, the at least one core element 8 and the at least one element 9, a wind turbine blade can be fabricated.

[0061] On the further component 9, additional sensing devices 10 are attached, so that during the resin-based infusion process, also a resin infusion into the further component 9 can be measured using the measurement devices 5.

[0062] As it is depicted in FIG. 3, two mandrels 11 are placed in the interior 2 of the mold 1 as supporting elements for supporting the component 7, the core component 8 and the further component 9 towards each other during the casting process. It is possible that also in between the mandrels 11, one or more further sensing devices 10 are arranged.

[0063] In FIG. 4, an additional component 12, an additional core component 13 as well as an additional further component 14 are placed on top of the mandrels 11 for creating the member fabricated in the casting process. The additional component 12 and the additional further component are each a glass fiber mat according to the component 7, or the additional component 9, respectively. It is possible that sensing devices 4 and/or additional sensing devices 10 are attached to the additional component 12 and/or the additional further component 14 as well.

[0064] As is shown in FIG. 5, an upper part 16 of the mold is then placed on top of the components in the interior 2 of the mold 1 enclosing the entire interior 2 of the mold 1. Afterwards, a vacuum is applied to the interior 2 of the mold 1, so that air inside the interior 2 and/or air inside the components, in particular in the components 7, 12 and the further components 9, 14 provided as textile structures, is removed.

[0065] Afterwards, as it is depicted in FIG. 6, from an inlet 17 resin is provided to the interior of the mold as depicted by the arrows 18. By using the sensing devices 4, 10, the ingress of the resin into the interior 2 of the mold 1, or the components 7, 9, respectively, can be determined. For instance, when the resin has already reached the position of the sensing devices 4 and 10 on the left side of the mold 1, the property of the sensing devices 4 and 10 changes, so that the contact of the sensing devices 4, 10 on the left side of the mold 1 can be measured by the measurement device 5 on the left side of the mold 1. If for instance, at the same time, the resin has not yet reached the position of the sensing devices 4, 10 on the right hand side of the mold 1, the measurement device 5 on the right hand side of the mold 1 does not measure a change in the property of the sensing devices 4, 10 on the right hand side of the mold 1.

[0066] As it is depicted in FIG. 7, the sensing devices 4, 10, which are provided as RFID elements, are passively powered by the measurement device 5, in particular by an electromagnetic field emitted from the measurement device 5, as indicated by the arrows 15. This has the advantage that the sensing devices 4, 10 do not have to contain a power source by themselves, so that no batteries or the like have to be included in the sensing devices 4, 10.

[0067] The RFID elements used as sensing devices 4 each comprise an antenna, which absorbs part of the energy emitted from the measurement device 5 and send back a signal to the measurement device 5, wherein a contact of the sensing device 4, 10 with the resin, can be detected as a change in the RF impedance of the antenna of the respective sensing device 4, 10. Also, a combination of passively powered sensing devices 4 and actively powered sensing devices is possible, in particular if for some of the sensing devices are arranged in a larger distance to the measurement device, for instance in between the mandrels 11, so that an active transmission of actively powered sensing devices may be used to bridge the distance to the measurement devices 5.

[0068] It is possible that at an outer surface 19 of the mold 1, one or more heating pipes 20 of a heater of the mold 1 are arranged, wherein depending on the position of the measurement device 5, a correction of the received signals from the sensing devices 4, 10 is conducted taking into account the obstruction by the heating pipes 20.

[0069] In FIG. 8, a perspective view of the mold 1 is shown, wherein as a component casted inside the mold 1, a wind turbine blade 21 is fabricated. On the outer surface of the mold 1, a plurality of measurement devices 5 is arranged, each adjacently to one or more sensing devices 4 attached to the mold 1 and/or to the component 7 and/or to one further sensing device 10 attached to a further component 9.

[0070] The measurement devices 5 are each connected to a computing device 22, wherein the computing device 22 determines a temperature and/or a resin distribution information describing the resin distribution in the mold 1 and/or in the at least one component 7, or the further component 9, respectively. Therefore, all measurement devices 5 are connected to the computing device 22 (not all connections shown), so that the temperature and/or the resin distribution can be determined with a sufficient spatial resolution.

[0071] It is possible that the computing device 22 is connected to at least one valve of a further inlet (not shown) of the mold 1 used for providing resin to the mold 1. This allows for controlling the resin infusion into the mold 1 by subsequently opening of the valves of one or more further inlets of the mold 1, so that for instance the entrapment of air inside the mold during the casting process can be avoided. Furthermore, the computing device 22 may comprise a display unit 23, on which the resin distribution information is depicted. The computing device 22 also controls the heater of the mold 1 to heat the heating pipes 20 in dependence of the temperature determined using the sensing devices. The sensing devices 4, 10 may be regularly used to determine the temperature and/or the resin distribution in the mold 1, for instance once every minute.

[0072] It is possible that the sensing devices 4, 10 each comprise a temperature measurement unit, which determines a temperature information corresponding to a temperature of the sensing device 4, 10. The temperature information can be transmitted to the measurement devices 5 during a read-out process of the sensing devices 4, 10 and sent to the computing device 22. The temperature measurement using the temperature measurement unit of the sensing devices 4, 10 may be conducted in addition or alternatively to a temperature measurement using a temperature-dependent change in a property of the sensing elements 4, 10. The sensing devices 4, 10 and/or the measurement devices 5 comprises a temperature accuracy of at least 1° C. by evaluating the property of the sensing device and/or by using the temperature measurement unit of the sensing device 4, 10, respectively.

[0073] It is possible that the sensing devices 4, 10 each comprise an identification unit, which provides an identification information specific to the sensing device 4, 10, a pressure measurement unit, which determines a pressure information corresponding to a pressure acting on the sensing device 4, 10 and/or a capacity measurement unit, which determines a capacitance information corresponding to an electrical capacitance of a vicinity of the sensing device 4, 10.

[0074] Also, the identification information, the pressure information and/or the capacitance information can be read out by the measurement devices 5 and in particular also be sent to the computing device 22. The additional information obtained at the computing device 22 may be displayed on the display unit 23, so that for instance an operator can control the information or the parameters described by the information, respectively.

[0075] Additionally or alternatively to the measurement devices 5 attached to the outer surface of the mold 1, hand held devices can be used as measurement devices 5 to measure the property of the sensing devices 4, 10 that changes when the sensing device 4, 10 comes into contact with the resin. This allows for instance for using an increased number of sensing devices 4, 10 in production processes of prototypes and/or during production tests, so that not for each of the sensing devices 4, 10 arranged inside the interior 2 of the mold 1, a measurement unit 5 has to be mounted to the exterior of the mold 1.

[0076] In FIG. 9, a wind turbine blade 21 fabricated in a method according to the present invention is shown. It is possible that the wind turbine blade 21 comprises one or more of the sensing devices 4, 10 on an exterior or interior surface of a shell structure of the wind turbine blade 21 and/or in between the components forming the shell structure of the wind turbine blade 21.

[0077] Although the present invention has been described in detail with reference to the preferred embodiment, the present invention is not limited by the disclosed examples from which the skilled person is able to derive other variations without departing from the scope of the invention.

[0078] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0079] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.