Method for manufacturing wind turbine rotor blade or longitudinal section thereof

Abstract

A method for manufacturing a wind turbine rotor blade or a longitudinal section of a wind turbine rotor blade, the wind turbine rotor blade or the longitudinal section having a longitudinal axis, the method comprising the steps of: providing a first wind turbine rotor blade shell component (10) having an end section (14) wherein the end section (14) comprises a laminate, the laminate has an outer surface (16) and an inner surface (18) and a laminate thickness (20) measured between the outer surface (16) and the inner surface (18), in which the first wind turbine rotor blade shell component (10) is arranged in a first mold (30), and when the first wind turbine rotor blade shell component (10) is arranged in the first mold (30), the laminate thickness (20) is measured between the outer surface (16) and the inner surface (18). Bonding a first reinforcing frame member (22) to the inner surface (18) of the laminate of the end section (14) of the first wind turbine rotor blade shell member (10), the first reinforcing frame member (22) extending in a circumferential direction and having a height (38) of at least 50% of the laminate thickness (20) measured in a radial direction, providing a second wind turbine rotor blade shell member having an end section (14), connecting the first wind turbine rotor blade shell member (10) and the second wind turbine rotor blade shell member to each other such that an access opening is formed between the first reinforcing frame member (22) and the second wind turbine rotor blade shell member.

Description

BACKGROUND

[0001] Wind turbine rotor blades comprise a shell defining the aerodynamic shape of the wind turbine rotor blade. To handle the large amount of loads in operation, various structural members such as spar caps and shear webs need to be integrated into or connected to the shell.

[0002] At the root end, where it is to be connected to the wind turbine rotor hub, the wind turbine rotor blade has a substantially circular cross section with a relatively thick laminate, often with embedded joining elements, in order to transfer loads from the wind turbine rotor blade to the wind turbine rotor hub. Most wind turbine rotor blades comprise a bulkhead in the root section. During maintenance, the bulkhead serves as a work platform and also prevents material, tools and even maintenance personnel from falling into the wind turbine rotor blade. In operation, the bulkhead further prevents debris from falling from the wind turbine rotor blade into the wind turbine rotor hub.

[0003] Although the wind turbine rotor blade root section is relatively rigid, the loads acting on the wind turbine rotor blade during operation and during prolonged storage periods can cause a certain deformation of the wind turbine rotor blade root section, often referred to as ovalization. This deformation can lead to failure of the wind turbine rotor blade structure or to problems with the pitch bearing or other elements important for the desired operation of the wind turbine rotor.

[0004] From document EP 2 497 941 B1 a wind turbine rotor blade with a root end bulkhead and a related method are known. The bulkhead is mounted to the inner wall of the wind turbine rotor blade shell via an attachment part comprising an elastomeric material. The elasticity of the attachment part shall make it easy to mount the bulkhead in the blade, as the attachment part can be folded into the opening of the wind turbine blade root. Furthermore, the elasticity of the attachment part shall solve the problem that the bulkhead can tear loose from the inner blade wall due to ovalization.

[0005] From document EP 2235 364 A1 a wind turbine rotor blade with a flexible flange for mounting a blade root bulkhead is known. The flange shall provide stress relief for the bulkhead.

[0006] From document WO 2020 / 086560 A1 a method of manufacturing a wind turbine rotor blade is known. A shear web is assembled with two sections of a blade root bulkhead, which are glued to both sides of the shear web. The bulkhead sections can be D-shaped and can comprise a frame and a cover. Then, the assembly is placed in a lower wind turbine rotor blade half shell before placing the upper wind turbine rotor blade half shell on top. This shall make it easy to position the shear web without a specific gantry, as the bulkhead sections serve as assembly guides.

[0007] From document EP 3 447 280 B1 a bulkhead unit for a wind turbine rotor blade is known. It comprises a plate-like central part arranged in radial direction. The central part is connected to another peripheral bulkhead element which provides a mounting flange which is attached to an inner wall of a wind turbine rotor blade root section. The central part can be supported by a frame structure so that it can carry additional parts of the wind turbine rotor, such as elements of a de-icing system. The bulkhead unit shall be pre-assembled and then lifted into an assembly position in the wind turbine rotor blade root section with a dedicated lifting equipment.

[0008] From document US 2014 / 0377078 Al a wind turbine rotor blade with a root reinforcement is known. The root reinforcement shall serve to reduce the occurrence and / or the amount of ovalization of a root portion of the wind turbine rotor blade. The root reinforcement is annular and mounted to an inner circumference of the root portion.

[0009] To this end, the root reinforcement defines a plurality of radially oriented openings configured to receive fasteners for coupling the root reinforcement to the root portion.

[0010] From document US 2015 / 0093250 Al a wind turbine rotor blade with a root reinforcement assembly is known. The root reinforcement assembly shall serve to reduce the occurrence and / or the amount of ovalization of a root portion of the wind turbine rotor blade. The root reinforcement assembly comprises a plurality of reinforcement ribs coupled to the root portion so as to extend along an inner surface of the root portion. The plurality of reinforcement ribs can be connected to each other so as to form a ring within the root portion. SUMMARY

[0011] Starting therefrom, it is an object of the present invention to provide a method for manufacturing a wind turbine rotor blade or a longitudinal section of a wind turbine rotor blade which is particularly rigid and shape accurate.

[0012] This object is solved by the method of claim 1. Preferred aspects are given in the dependent claims.

[0013] The method is for manufacturing a wind turbine rotor blade or a longitudinal section of a wind turbine rotor blade, wherein the wind turbine rotor blade or the longitudinal section has a longitudinal axis. The method comprises the following steps:

[0014] • providing a first wind turbine rotor blade shell member having an end section, wherein the end section comprises a laminate having an outer surface and an inner surface and a laminate thickness measured between the outer surface and the inner surface, wherein the first wind turbine rotor blade shell member is arranged in a first mold,

[0015] • joining a first stiffening frame member to an inner surface of the laminate of the end section of the first wind turbine rotor blade shell member when the first wind turbine rotor blade shell member is arranged in the first mould, the first stiffening frame member extending along a circumferential direction and having a height of at least 50% of a laminate thickness measured in a radial direction,

[0016] • providing a second wind turbine rotor blade shell member having an end section,

[0017] • connecting the first wind turbine rotor blade shell member and the second wind turbine rotor blade shell member to each other such that an access opening is formed between the first stiffening frame member and the second wind turbine rotor blade shell member.

[0018] The method can be used for manufacturing a wind turbine rotor blade having a wind turbine rotor blade root and a wind turbine rotor blade tip. The wind turbine rotor blade can be suitable for a wind turbine having a horizontal axis rotor. The method can also be used for manufacturing a longitudinal section of a wind turbine rotor blade. The longitudinal section can comprise the wind turbine rotor blade root or the wind turbine rotor blade tip. The longitudinal section can also be a middle section of the wind turbine rotor blade having neither the wind turbine rotor blade root nor the wind turbine rotor blade tip.

[0019] The first wind turbine rotor blade shell member and the second wind turbine rotor shell member can be wind turbine rotor blade halves, such as pressure side and suction side halves, or, if a longitudinal section of a wind turbine rotor blade is to be manufactured, longitudinal sections of such halves. The first wind turbine rotor blade shell member and the second wind turbine rotor blade shell member can be the only shell members of the wind turbine rotor blade or of the longitudinal section thereof, or they can be combined with one or more additional shell members to form the entire wind turbine rotor blade or the longitudinal section thereof. For example, when the first wind turbine rotor blade shell member and the second wind turbine rotor blade shell member are suction side and pressure side halves, they can both extend from a wind turbine rotor blade leading edge to a wind turbine rotor blade trailing edge. However, additional wind turbine rotor blade shell members, such as trailing edge shell members, can be combined with the first wind turbine rotor blade shell member and the second wind turbine rotor blade shell member to form the entire wind turbine rotor blade or the longitudinal section thereof.

[0020] In any case, the first and the second wind turbine rotor blade shell member each have an end section. These end sections form an end section of the wind turbine rotor blade or of a longitudinal section thereof. In particular, they can form a wind turbine rotor blade root section adapted to be connected to a wind turbine rotor hub. However, the end sections can also be sections arranged in an intermediate longitudinal position of the wind turbine rotor blade, adapted to be connected to another longitudinal section of the wind turbine rotor blade. The end section of the wind turbine rotor blade or of a longitudinal section thereof substantially formed by the end sections of the first and the second wind turbine rotor blade shell member can be circular, in particular when the end sections correspond to a wind turbine rotor blade root section, or can have an elliptical shape or the shape of an aerodynamic airfoil when the end sections are arranged in an intermediate position of the wind turbine rotor blade.

[0021] The end sections of the first and the second wind turbine rotor blade shell member each comprise a number of plies of a reinforcing fiber material, such as glass fibers or carbon fibers. For example, the plies can comprise 20 or more layers of fiber material and can have a ply thickness of 50 mm or more. Typically, the end sections each comprise a plurality of joining elements, such as steel sleeves with internal threads, adapted to be connected to the wind turbine rotor hub or to another longitudinal section of the wind turbine rotor blade by means of threaded bolts. In particular, the joining elements can be embedded in the plies of the respective end section.

[0022] The first wind turbine rotor blade shell member is arranged in a first mold, in particular a first manufacturing mold, wherein the first wind turbine rotor blade shell member has been manufactured by placing various fiber materials and potentially additional structural elements, such as a core material or a pre-fabricated fiber-reinforced composite part, placing a liquid polymer in the mold such that all other elements are embedded in the liquid polymer and solidifying the polymer. The first wind turbine rotor blade shell member can be manufactured in the first mold, in particular using a vacuum infusion process. The first mold has a mold surface corresponding to the outer / aerodynamic surface of the first wind turbine rotor blade shell member manufactured in the first mold.

[0023] In a second step of the method, the first stiffening frame member is joined to an inner surface of the plies of the end section of the first wind turbine rotor blade shell member when the first wind turbine rotor blade shell member is (still) arranged in the first mold. This means that when the first stiffening frame member is joined to the first wind turbine rotor blade shell member, the first wind turbine rotor blade shell member still maintains the desired shape of the first wind turbine rotor blade shell member defined by the first mold when the first stiffening frame member is connected to the first wind turbine rotor blade shell member.

[0024] The first stiffening frame member extends along a circumferential direction, e.g. along an inner circumference of the circular end section, e.g. at the root of the wind turbine rotor blade. The first stiffening frame member can be arranged in a plane perpendicular to a longitudinal direction of the wind turbine rotor blade or a longitudinal section thereof. The first stiffening frame member has a height of at least 50% of a laminate thickness measured in a radial direction. The laminate thickness is measured between an outer surface and an inner surface of the end section, in particular at a longitudinal position of the end section where the first stiffening frame member is placed.

[0025] The height can also be greater, e.g. up to 100% of the laminate thickness, up to 200% of the laminate thickness, up to 300% of the laminate thickness or up to 500% of the laminate thickness. The first stiffening frame member is a rigid structural element which provides additional stiffness to the end section of the first wind turbine rotor blade shell member by means of its stiffness and height.

[0026] The step of incorporating the first stiffening frame member to the inner surface of the laminate can comprise forming an adhesive bond using an adhesive, e.g. a liquid polymer as explained before, and can also comprise curing the adhesive. Thus, the stiffness added by the first stiffening frame member takes effect while the first wind turbine rotor blade shell member is still in its manufacturing mold. This means that the first stiffening frame member will help to maintain the first wind turbine rotor blade shell member in its desired shape when it is demolded.

[0027] In the remaining steps of the method, a second wind turbine rotor blade shell member having an end section is provided and connected to the first wind turbine rotor blade shell member. After this connection, there is an access opening between the first stiffening frame member and the second wind turbine rotor blade shell member. The access opening can have a size large enough so that a person can easily access the interior of the wind turbine rotor blade or a longitudinal section thereof through the access opening.

[0028] The main advantage of the inventive method is that the first wind turbine rotor blade shell member is already provided with the first stiffening frame member while it is still in the first mold. When the first wind turbine rotor blade shell member is demolded, the first stiffening frame member prevents any ovalization or other deformation of the first wind turbine rotor blade shell member immediately during further manufacturing steps and during storage and transportation. At the same time, any work required inside the wind turbine rotor blade or a longitudinal section thereof can be easily performed as it is still easily accessible through the access opening.

[0029] In an aspect, the end section of the second wind turbine rotor blade shell member comprises a laminate having an outer surface and an inner surface and a laminate thickness measured between the outer surface and the inner surface, wherein the second wind turbine rotor blade shell member is arranged in a second mold, wherein the method comprises the further steps of:

[0030] • coupling a second stiffening frame member to the inner surface of the laminate of the end section of the second wind turbine rotor blade shell member when the second wind turbine rotor blade shell member is arranged in the second mold, the second stiffening frame member extending along a circumferential direction and having a height of at least 50% of the laminate thickness of the end section of the second wind turbine rotor blade shell member measured in a radial direction,

[0031] wherein the entry opening is formed between the first stiffening frame member and the second stiffening frame member.

[0032] In this aspect, the second wind turbine rotor blade shell member is stabilized by the second stiffening frame member coupled thereto in the same way as explained above for the first wind turbine rotor blade shell member. Then, the entry opening is formed between the first stiffening frame member and the second stiffening frame member.

[0033] In an aspect, the first stiffening frame member and / or the second stiffening frame member is a preform comprising a fiber-reinforced composite material, wherein the fiber-reinforced composite material has been cured before the respective stiffening frame member is placed in the respective mold. In general, the stiffening frame members can also be made of e.g. metal. Another option is to use a fiber-reinforced composite material for the stiffening frame members and to cure this fiber-reinforced composite material in the mold only together with the material forming the first and / or second wind turbine rotor blade shell member. However, the use of preforms allows to form particularly well-defined, rigid and lightweight stiffening frame members.

[0034] In an aspect, the first stiffening frame member and / or the second stiffening frame member has a T-shaped cross section. The "horizontal bar" of the T forms the double-sided flange section of the stiffening frame and is connected to the inner surface of the laminate of the end section of the respective wind turbine rotor blade shell member. The "vertical bar" of the T corresponds to the height of the stiffening frame and provides the desired stabilization. In this way, a particularly stable coupling is obtained. Similar effects can be achieved with a first stiffening frame member and / or a second stiffening frame member having an I-shaped, C-shaped or L-shaped cross section, wherein the "horizontal bar" of the I, C or L is connected to the inner surface of the laminate of the end section of the respective wind turbine rotor blade shell member.

[0035] In an aspect, the first and second stiffening frame members form an open or closed stiffening ring. The stiffening ring can be circular. An open stiffening ring means that there is a gap between the first and second stiffening frame members, preferably on both sides. The gap is located in the area of the joining flanges between the first and second rotor blade shell members. It provides a good access to this area for inspecting the adhesive bond. A closed stiffening ring means that the first and second stiffening frame members are in contact at their ends. When both stiffening frame members together form a ring, a particularly effective stabilization against ovalization and other deformations is obtained.

[0036] In an aspect, the step of bonding the first and / or second stiffening frame member to the respective wind turbine rotor blade shell member is performed after the respective wind turbine rotor blade shell member is cured. Adhesive is placed between the respective stiffening frame member and the respective wind turbine rotor blade shell member and forms an adhesive bond therebetween. This allows curing the respective wind turbine rotor blade shell member without having to take into account the adjacent stiffening frame member, which can be an obstacle, for example, when closing the respective mold with a vacuum foil.

[0037] In an aspect, the step of bonding the first and / or second stiffening frame member to the respective wind turbine rotor blade shell member is performed together with the step of manufacturing the respective wind turbine rotor blade shell member by means of pouring or injecting a liquid polymer into the respective mold. The liquid polymer connects the respective stiffening frame member and the respective wind turbine rotor blade shell member and forms an adhesive bond therebetween. This particular process allows forming a nearly perfect bond between the respective wind turbine rotor blade shell member and the adjacent stiffening frame member, in particular when the stiffening frame member is provided as a pre-fabricated component.

[0038] In an aspect, the step of bonding the first and / or second stiffening frame member to the respective wind turbine rotor blade shell member comprises placing a layer of fibrous material on top of the inner surface of the respective end section and on top of the surface of the respective stiffening frame member. Preferably, the layer is placed on both sides of the first and / or second stiffening frame member. It can at least partially cover the inner surface of the rotor blade shell member and the flanges of the T-shaped stiffening frame. The layer of fibrous material further strengthens the bond and provides a smooth transition between the different components.

[0039] In one aspect, after the step of connecting the first wind turbine rotor blade shell member and the second wind turbine rotor blade shell member, the first stiffening frame member and the second stiffening frame member are connected to each other by a layer of fiber material laminated on the surface of the first stiffening frame member and the surface of the second stiffening frame member. This additional layer of fiber material further stiffens the stiffening structure formed by the stiffening frame members, in particular the stiffening ring.

[0040] In one aspect, before the wind turbine rotor blade shell member is demolded, a reinforcement rod is connected to the first stiffening frame member and / or the second stiffening frame member, wherein the reinforcement rod is connected to two opposite points of the stiffening structure formed by the first stiffening frame member and / or the second stiffening frame member. The reinforcement rod provides an additional stiffening means. It can in particular be used during further manufacturing and / or storage of the wind turbine rotor blade or a longitudinal section thereof, and can be removed and / or replaced later by another structure, such as a root bulkhead, see below.

[0041] In one aspect, after the wind turbine rotor blade shell member is demolded, a root bulkhead is mounted to the first stiffening frame member and / or the second stiffening frame member. In particular, the root bulkhead is only mounted after the work necessary to be performed inside the wind turbine rotor blade is finished. The stiffening frame members provide a particularly stable structure for mounting the root bulkhead thereto. The root bulkhead itself does not need to contribute to providing additional stiffness, it can only serve as a platform during maintenance work, as explained above. Mounting the root bulkhead to the stiffening frame members is also particularly easy, as the root bulkhead does not need to fit perfectly to the inner surface of the laminate of the respective end section.

[0042] In one aspect, the first stiffening frame member and / or the second stiffening frame member comprises a positioning element for arranging the root bulkhead in a desired position. This makes it easier to join the root bulkhead to the stiffening frame member. For example, one or more pins can be used as positioning elements.

[0043] In one aspect, the outer diameter of the root bulkhead is smaller than the inner diameter defined by the inner surface of the end section. This makes it particularly easy to place the root bulkhead in the end section.

[0044] In one aspect, a shear web is joined to the first wind turbine rotor blade shell member and / or the second wind turbine rotor blade shaft member, the shear web having end sections joined to the first stiffening frame member and / or the second stiffening frame member. Joining the shear web to the stiffening frame members provides additional stability both for securing the shear web and for preventing deformation of the end sections. BRIEF DESCRIPTION OF DRAWINGS

[0045] In the following, the application is explained in more detail with reference to the drawings.

[0046] Figure 1 End section of a first wind turbine rotor blade shell member with a first stiffening frame member is shown in perspective view,

[0047] Figure 2 End section of a first wind turbine rotor blade shell member with a shear web is shown in perspective view, Figure 1

[0048] Figure 3 Part with the arrangement of reinforcing rods of Figure 2

[0049] Figure 4 Longitudinal section through a first wind turbine rotor blade shell member with a first stiffening frame member is shown in schematic view,

[0050] Figure 5 Another longitudinal section through a first wind turbine rotor blade shell member with a first stiffening frame member is shown in schematic view,

[0051] Figure 6 Another longitudinal section through a first wind turbine rotor blade shell member with a first stiffening frame member and a shear web is shown in schematic view,

[0052] Figure 7 Yet another longitudinal section through a first wind turbine rotor blade shell member with a first stiffening frame member and a shear web is shown in schematic view,

[0053] Figure 8 First wind turbine rotor blade shell member of Figure 2

[0054] Schematic view showing three steps of a method for manufacturing a wind turbine rotor blade, and Figures 9a to 9c

[0055] Figure 10 Wind turbine rotor blade is shown in perspective view. DETAILED DESCRIPTION

[0056] Figure 10 ​​​A wind turbine rotor blade 56 with a longitudinal axis 12 is shown. The wind turbine rotor blade 56 includes an end section 14 having a wind turbine blade root 66. The end section 14 is cylindrical. An outer longitudinal section 58 includes a wind turbine rotor blade tip 60 and has an aerodynamic airfoil 62. Between the end section 14 and the outer longitudinal section 58, the wind turbine rotor blade 56 has an intermediate section 64 that forms a transition between the cylindrical cross-section of the end section 14 and the aerodynamic airfoil 62 of the outer longitudinal section 58. The wind turbine rotor blade 56 includes a suction-side half-shell 70 and a pressure-side half-shell 68, the suction-side half-shell 70 being a first wind turbine rotor blade shell component and the pressure-side half-shell 68 being a second wind turbine rotor blade shell component.

[0057] The end section 14 is provided with a reinforcing frame, which includes a first reinforcing frame member 22 and a second reinforcing frame member 52.

[0058] Figure 1 The first wind turbine rotor blade shell assembly 10 has a longitudinal axis 12, which corresponds to the longitudinal axis 12 of a wind turbine rotor blade formed using the first wind turbine rotor blade shell assembly 10 by the method of the present invention. The wind turbine rotor blade shell assembly 10 has an end section 14, which will form part of the root section of the wind turbine rotor blade. The end section 14 includes a laminate having an outer surface 16 and an inner surface 18, and includes a laminate thickness 20 measured between the outer surface 16 and the inner surface 18.

[0059] basically, Figure 1 Only the end section 14 of wind turbine rotor blade shell 10 is shown. In the direction away from the observer, the wind turbine rotor blade shell component 10 can extend upward to the tip of the wind turbine rotor blade (not shown). The first wind turbine rotor blade shell component 10 is then followed by the first wind turbine rotor blade half-shell.

[0060] The first reinforcing frame member 22 extends along the entire inner semicircle circumferentially bounded by the end segment 14. The first reinforcing frame member 22 is attached to the inner surface 18 of the end segment 14.

[0061] Figure 2 It shows Figure 1 The component is combined with the shear web 24, which extends in the longitudinal direction 12 and is also integrated into the inner surface 18 of the end segment 14. Figure 2Only those components of the shear web 24 are shown which are arranged within the end section 14. It is to be understood that the shear web 24 actually extends further along the longitudinal direction, away from the observer, and can reach or approach the wind turbine rotor blade tip (not shown).

[0062] Figure 3 The element of Figure 2 is shown, wherein only the lower half of the shear web 24 is shown. In addition to the element of Figure 2 , Figure 3 the reinforcing rods 26 are also shown, which are each fastened to the two opposite ends of the first reinforcing frame member 22 by two bolts 28.

[0063] Figure 4 A longitudinal section of the element of Figure 1 along the longitudinal axis 12 is shown. At the bottom of Figure 4 , there is a mold 30, in which the other elements are placed. The inner surface of the mold 30 corresponds to the outer surface of the first wind turbine rotor blade shell member 10 manufactured therein. On top of this inner surface, a laminate 32 is arranged which comprises various layers of fiber material. The laminate thickness 20, measured between the outer surface 16 and the inner surface 18 of the end section 14, varies slightly along the length of the end section 14.

[0064] The first reinforcing frame member 22 is a prefabricated part of a fiber-reinforced composite material. The first reinforcing frame member 22 is shown on top of the inner surface 18 of the end section 14. It is shown in cross section. The cross section of the first reinforcing frame member 22 is T-shaped, wherein a horizontal bar 34 forms two flanges which are bonded to the inner surface 18 of the end section 14, and a vertical bar 36 defines the height 38 of the first reinforcing frame member 22. The height 38 of the first reinforcing frame member 22 is greater than the laminate thickness 20 at the longitudinal position of the end section 14 where the first reinforcing frame member 22 is placed.

[0065] Figure 4 It is also shown how the first reinforcing frame member 22 is bonded to the end section 14. In the embodiment of Figure 4 , this is done simultaneously with the vacuum infusion process for manufacturing the first wind turbine rotor blade shell member 10. For this purpose, the first reinforcing frame member 22 is placed on the fiber material of which the laminate forming the end section 14 is made. An additional layer of fiber material, in particular of bi-axial glass fiber material, is placed on the inner surface 18 as well as on a surface 42 on the upper side of the "horizontal bar" of the T-shaped first reinforcing frame member 22. Then, a vacuum foil 44 is arranged on top and connected to the boundaries of the mold and to both sides of the first reinforcing frame member 22, so that a vacuum infusion of resin can be performed. In this way, a firm bond between the first reinforcing frame member 22 and the end section 14 is obtained.

[0066] Figure 5 An alternative to the bonding process of Figure 4 is shown. Here, the first wind turbine rotor blade shell member 10 and its end section 14 are first cured together with the inner layer 40 of fibre material forming the inner surface 18 of the end section 14. Then, the first stiffening frame member 22 is bonded to the inner surface 18 of the end section 14 by means of an adhesive 46 placed between the first stiffening frame member 22 and the inner surface 18.

[0067] Figure 6 An alternative to the bonding process of Figure 4 is shown. Here, the first wind turbine rotor blade shell member 10 and its end section 14 are first cured together with the inner layer 40 of fibre material forming the inner surface 18 of the end section 14. Then, the first stiffening frame member 22 is bonded to the inner surface 18 of the end section 14 by means of an adhesive 46 placed between the first stiffening frame member 22 and the inner surface 18.

[0068] Figure 7 An alternative to the bonding process of Figure 4 is shown. In this alternative, the shear web 24 does not have an end section 48 directly contacting the first stiffening frame member 22. Instead, the shear web 24 is only bonded to the inner surface 18 of the end section. As already explained with reference to Figure 6 , the root bulkhead 50 is bonded to the first stiffening frame member 22.

[0069] Figure 8 The elements of Figure 2 are again shown after these elements have been connected to a second wind turbine rotor blade shell member (not shown) and a second stiffening frame member 52, thereby forming a (closed) stiffening ring. It can be seen that a large access opening is formed between the first stiffening frame member 22 and the second stiffening frame member 52. In Figure 8 , this access opening is not closed with a root bulkhead 50, but with a mesh 54 which does not provide any stiffening effect, but still protects the wind turbine from losing components falling from the wind turbine rotor blade 10.

[0070] Figures 9a to 9c Three stages of a method for manufacturing a wind turbine rotor blade are illustrated. Figure 9aA first wind turbine rotor blade shell member 10 (e.g. suction side half shell) with already assembled shear web 75 arranged in a first mold 30 is shown on the left side and a second wind turbine rotor blade shell member 72 (e.g. pressure side half shell) arranged in a second mold 74 is shown on the right side.

[0071] In Figure 9b , the same elements are shown after the first stiffening frame member 22 has been joined to the first wind turbine rotor blade shell member 10 and the second stiffening frame member 52 has been joined to the second wind turbine rotor blade shell member 72. The first wind turbine rotor blade shell member 10 and the second wind turbine rotor blade shell member 72 are still arranged in the respective molds 30, 74. The second stiffening frame member 52 is provided with a reinforcement rod 26. Alternatively, the reinforcement rod 26 can be provided at the first stiffening frame 22.

[0072] Figure 9c Elements of Figure 9b are shown after the second mold 74 together with the second wind turbine rotor blade shell member 72 and the second stiffening frame member 52 joined thereto have been placed on top of the first wind turbine rotor blade shell member 10 and the first mold 30. In this position and while still in their respective molds 30, 74, the first wind turbine rotor blade shell member 10 and the second wind turbine rotor blade shell member 72 are connected to each other. Between the two stiffening frame members 22, 52, an access opening 76 is formed.

[0073] List of reference signs

[0074] 10 first wind turbine rotor blade shell member

[0075] 12 longitudinal axis

[0076] 14 end section

[0077] 16 outer surface

[0078] 18 inner surface

[0079] 20 laminate thickness

[0080] 22 first stiffening frame member

[0081] 24 shear web

[0082] 26 reinforcement rod

[0083] 28 bolt

[0084] 30 (first) mold

[0085] 32 laminate

[0086] 34 "horizontal leg" of T

[0087] 36 "vertical leg" of T

[0088] 38 height

[0089] 40 layer of fibrous material

[0090] 42 surface

[0091] 44 vacuum foil

[0092] 46 adhesive

[0093] 48 end section of shear web

[0094] 50 root bulkhead

[0095] 52 second stiffening frame member

[0096] 54 web

[0097] 56 wind turbine rotor blade

[0098] 58 outer longitudinal section

[0099] 60 wind turbine rotor blade tip

[0100] 62 aerodynamic airfoil

[0101] 64 intermediate section

[0102] 66 wind turbine blade root

[0103] 68 pressure side half shell

[0104] 70 suction side half shell 70

[0105] 72 second wind turbine rotor blade shell member

[0106] 74 second mold

[0107] 75 shear web

[0108] 76 entry opening

Claims

1. A method for manufacturing a wind turbine rotor blade or a longitudinal section of a wind turbine rotor blade, said wind turbine rotor blade or longitudinal section having a longitudinal axis, said method comprising the following steps: A first wind turbine rotor blade shell component (10) is provided having an end section (14), wherein the end section (14) includes a laminate having an outer surface (16) and an inner surface (18) and a laminate thickness (20) measured between the outer surface (16) and the inner surface (18), wherein the first wind turbine rotor blade shell component (10) is arranged in a first mold (30). • When the first wind turbine rotor blade shell component (10) is arranged in the first mold (30), a first reinforcing frame component (22) is attached to the inner surface (18) of the laminate of the end section (14) of the first wind turbine rotor blade shell component (10), the first reinforcing frame component (22) extending in the circumferential direction and having a height (38) of at least 50% of the thickness (20) of the laminate measured in the radial direction. • Provides a second wind turbine rotor blade shell component having an end section (14), • Connect the first wind turbine rotor blade shell component (10) and the second wind turbine rotor blade shell component to each other, such that an access opening is formed between the first reinforcing frame component (22) and the second wind turbine rotor blade shell component.

2. The method according to claim 1, wherein, The end section (14) of the second wind turbine rotor blade shell component includes a laminate having an outer surface (16) and an inner surface (18) and a laminate thickness (20) measured between the outer surface (16) and the inner surface (18), wherein the second wind turbine rotor blade shell component is arranged in a second mold (30), wherein the method includes the further steps of: • When the second wind turbine rotor blade shell component is arranged in the second mold (30), a second reinforcing frame component (52) is attached to the inner surface (18) of the laminate of the end section (14) of the second wind turbine rotor blade shell component, the second reinforcing frame component extending in the circumferential direction and having a height (38) of at least 50% of the thickness (20) of the laminate of the end section (14) of the second wind turbine rotor blade shell component as measured in the radial direction. The access opening is formed between the first reinforcing frame member (22) and the second reinforcing frame member (52).

3. The method according to claim 1 or 2, wherein, The first reinforcing frame member (10) and / or the second reinforcing frame member are prefabricated components comprising fiber-reinforced composite materials, wherein the fiber-reinforced composite materials have been cured before the respective reinforcing frame member (22) is placed in the respective mold (30).

4. The method according to any one of claims 1 to 3, wherein, The first reinforcing frame member (22) and / or the second reinforcing frame member have a T-shaped cross section.

5. The method according to any one of claims 2 to 4, wherein, The first reinforcing frame member (22) and the second reinforcing frame member (52) form an open or closed reinforcing ring.

6. The method according to any one of claims 1 to 5, wherein, The step of incorporating the first reinforcing frame member (22) and / or the second reinforcing frame member (52) into the corresponding wind turbine rotor blade shell member (10) is performed after the corresponding wind turbine rotor blade shell member (10) has been cured.

7. The method according to any one of claims 1 to 5, wherein, The step of incorporating the first reinforcing frame member (22) and / or the second reinforcing frame member (52) into the corresponding wind turbine rotor blade shell member (10) is performed together with the step of manufacturing the corresponding wind turbine rotor blade shell member (10) by means of pouring or injecting liquid polymer into the corresponding mold (30).

8. The method according to any one of claims 1 to 7, wherein, The step of combining the first reinforcing frame member (22) and / or the second reinforcing frame member (52) into the respective wind turbine rotor blade shell member (10) includes placing a layer of fiber material (40) on top of the inner surface (18) of the respective end segment (14) and on the surface (42) of the respective reinforcing frame member (22, 52).

9. The method according to any one of claims 2 to 8, wherein, After the step of connecting the first wind turbine rotor blade shell component (10) and the second wind turbine rotor blade shell component, the first reinforcing frame component (22) and the second reinforcing frame component (52) are connected to each other by a layer of fiber material laminated on the surface of the first reinforcing frame component (22) and the surface of the second reinforcing frame component (52).

10. The method according to any one of claims 1 to 9, wherein, Before the wind turbine rotor blade shell component (10) is demolded, a reinforcing rod (26) is connected to the first reinforcing frame component (10) and / or the second reinforcing frame component, wherein the reinforcing rod (26) is connected to two opposite points of the reinforcing structure formed by the first reinforcing frame component (22) and / or the second reinforcing frame component (52).

11. The method according to any one of claims 1 to 10, wherein, After the wind turbine rotor blade shell component (10) is demolded, the root partition (50) is installed onto the first reinforcing frame component (22) and / or the second reinforcing frame component (52).

12. The method according to claim 11, wherein, The first reinforcing frame member (22) and / or the second reinforcing frame member (52) include positioning elements for arranging the root partition in a desired position.

13. The method according to claim 11 or 12, wherein, The outer diameter of the root partition (50) is smaller than the inner diameter defined by the inner surface (18) of the end section (14).

14. The method according to any one of claims 1 to 13, wherein, Shear web (24) is attached to the first wind turbine rotor blade shell member (10) and / or the second wind turbine rotor blade shell member, the shear web (24) having an end section (48) attached to the first reinforcing frame member (22) and / or the second reinforcing frame member (52).

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