Method of manufacturing wind turbine rotor blades

Abstract

Provided is a method of manufacturing wind turbine rotor blades, wherein each rotor blade includes an inboard section and an outboard section, and wherein an inboard blade section including a root end and a transition region is manufactured using a first casting process; and an outboard blade section including an airfoil region is manufactured using a second casting process, which second casting process is different from the first casting process. The invention further describes a wind turbine rotor blade manufactured using such a method.

Claims

1. A method of manufacturing wind turbine rotor blades, wherein each rotor blade comprises an inboard section and an outboard section, the method comprising: manufacturing the inboard blade section comprising a root end and a transition region using a first casting process; manufacturing the outboard blade section comprising an airfoil region using a second casting process, wherein the second casting process is different from the first casting process; providing a connector interface for connecting the inboard blade section and the outboard blade section, the connector interface disposed at least partially inside at least one of the inboard blade section and the outboard blade section; scheduling two workflow stages that occur consecutively; manufacturing three outboard sections and one inboard section simultaneously during a first of the two workflow stages; and manufacturing two inboard sections simultaneously during a second of the two workflow stages.

2. The method according to claim 1, wherein the first casting process is an open-mould casting process.

3. The method according to claim 1, wherein the second casting process is a closed-mould process.

4. The method according to claim 1, further comprising joining the inboard blade section to the outboard blade section to complete the rotor blade.

5. The method according to claim 1 wherein a duration of each of the two workflow stages is determined on a basis of a time required to manufacture the inboard blade section.

6. The method according to claim 1, wherein the inboard blade section and the outboard blade section are joined during one of the two casting processes.

7. The method according to claim 1, further comprising joining the inboard blade section and the outboard blade section after completion of both casting processes.

Description

BRIEF DESCRIPTION

(1) Some of the embodiments will be described in detail, with references to the following Figures, wherein like designations denote like members, wherein:

(2) FIG. 1 shows an embodiment of a wind turbine rotor blade manufactured using the inventive method;

(3) FIG. 2 shows the two sections of the blade of FIG. 1;

(4) FIG. 3 illustrates stages of an embodiment of the inventive method;

(5) FIG. 4 shows steps of a first casting process; and

(6) FIG. 5 shows steps of a second casting process.

DETAILED DESCRIPTION

(7) FIG. 1 shows an embodiment of a wind turbine rotor blade 1 manufactured using the inventive method. Both sections 1A, 1B are manufactured using different casting processes and joined together to make a seamless connection. FIG. 2 shows the blade sections 1A, 1B as they might appear if each blade section 1A, 1B is manufactured separately.

(8) The rotor blade 1 comprises a root end 10, a transition region 11, and an airfoil 12. The transition region 11 is shaped to make a smooth transition between the (usually) circular root end 10 and the airfoil. The blade 1 is assembled from two sections 1A, 1B as indicated by the dotted line in FIG. 1, for example by means of an interface 14 indicated in FIG. 2. The inboard blade section 1A comprises the root end 10, the transition region 11 and part of the airfoil 12. The outboard blade section 1B comprises the remainder of the airfoil 12.

(9) The blade 1 can have a length L of 70 m or more. The blade 1 is thickest in the transition region, firstly because this region is the widest part of the blade, and secondly because this part of the blade is subject to the highest loads during operation. The thickest part of the blade 1 generally also coincides with the longest chord as indicated by the largest airfoil shape C.sub.max in FIG. 2. The length L.sub.1A of the inboard section 1A may comprise at least 1% of the total blade length L, and comprises at least 10%, more at least 15% and most at least 20% of the total blade length L. The length L.sub.1A of the inboard section 1A may comprise up to 90% of the total blade length L, more up to 50%-80% of the total blade length L, and most up to 40% of the total blade length L. The length L.sub.1B of the outboard section 1B makes up the remainder of the total blade length L. Accordingly, a preferred length L.sub.1A of the inboard section 1A, expressed as a percentage of the total blade length L, lies within the range of 10%-90%, more in the range of 15%-80%, more in the range of 20%-60%, more in the range of 20%-50% and most in the range of 20%-40%.

(10) FIG. 3 illustrates stages S1, S2, S3 of an embodiment of the inventive method. Here, two casting workflow stages S1, S2 have been scheduled, for example to manufacture rotor blades for wind turbines that each requires three rotor blades. In a first workflow stage S1, a multiple of three outboard sections is manufactured, along with the same multiple of inboard sections. For example, six outboard sections and two inboard sections are manufactured simultaneously in workflow stage S1. In a subsequent process step S2, the remaining inboard sections are manufactured. Using the above example, the remaining four inboard sections are manufactured. In a third workflow stage S3, the six inboard sections are joined to the six outboard sections. With the method carried out as described here, a total of only four inboard section moulds is required for the manufacture of six blades.

(11) The third workflow stage S3 may be temporally independent of the first and second workflow stages S1, S2 if the blade sections 1A, 1B are manufactured separately. Alternatively, the third workflow stage S3 may be temporally related to the second workflow stage S2 if the previously manufactured outboard blade sections 1A are joined to the inboard sections before casting and curing the inboard sections 1B.

(12) FIG. 4 is a schematic representation of the process steps involved in a first casting process P1. This technique may also be referred to as the “butterfly” technique and is particularly suited to the manufacture of an inboard blade section as indicated here. Mould halves 40A, 40B are prepared in step P1.1 and layup is performed to prepare two section halves 1A_1, 1A_2. In step P1.2 the section halves 1A_1, 1A_2 are cast and cured separately (usually simultaneously). In step P1.3 a load-bearing spar or beam 41 is arranged in the interior, and the mould halves 40A, 40B are joined in step P1.4 and the cured section halves 1A_1, 1A_2 are then glued together in step P1.5. Once the glue has cured, the finished component—in this case an inboard blade section 1A—can be removed from the mould 40A, 40B.

(13) FIG. 5 is a schematic representation of the process steps involved in a second casting process P2. This technique may also be referred to as the “integral” technique and is particularly suited to the manufacture of an outboard blade section 1B as indicated here. A lower mould half 50A is prepared in step P2.1 and layup 1B_1 of the lower half is done in step P2.2. A mandrel 51 or similar element is arranged in place in step P2.3 to assist in shaping the upper half. Layup of the upper half 1B_2 is then completed in step P2.4. In a subsequent step P2.5, the upper mould half 50B is put into place, and the entire blade section 1B is cast and cured in step P2.6. Generally, the mandrel is removed at this point.

(14) The outboard blade section 1B can then be connected to an inboard blade section 1A manufactured as explained in FIG. 5 above. Alternatively, the outboard blade section 1B can be connected to an inboard blade section 1A before the inboard blade section 1B is cured, for example at some point between step P1.4 and step P1.5 above.

(15) 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.

(16) 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.