A method of securing a blade blunt trailing edge and a wind turbine blade

Abstract

The application provides a fixing method of a blade blunt trailing edge and a wind power blade, and the fixing method of the blade blunt trailing edge comprises the following steps: S1, bonding a wood board on a mold surface; S2, fixing a blunt trailing edge cloth layer; S3, fixing a blunt trailing edge core material and a sewing cloth; S4, arranging auxiliary materials; S5, assembling and debugging a clamping tool; and S6, vacuum suction and tightening. The glass fiber cloth and the core material are sewn together and turned out to be fixed on the flange through structural adjustment, and the wood board is bonded on the mold flange to centrally fix the blunt trailing edge cloth layer of the rear edge; after vacuum suction and tightening, the external clamping is fixed through the designed tool, the connection of the tight bell is achieved, the blunt trailing edge cloth layer and the core material are prevented from sliding down, and the consistency of the design is achieved.

Description

Technical Field

[0001] This invention relates to the field of wind turbine blade manufacturing technology, and more specifically, to a method for fixing the blunt trailing edge of a blade and a wind turbine blade. Background Technology

[0002] As a member of the new energy family, wind energy plays an important role in promoting the diversification of energy supply and protecting the ecological environment; and the blade is one of the most basic and critical components of the wind turbine. During the blade layup process, personnel need to be arranged to go to each location to carry out the layup work.

[0003] As the blade length, chord length, and root hub cross-section increase, the height of the blunt trailing edge gradually increases, and the corresponding fabric and core material also become thicker. This leads to fabric slippage, core material falling off, or demolding during the laying process. The blunt trailing edge core material and fiberglass fabric layer of the blade slippage and accumulate wrinkles that run through the entire blunt trailing edge structure, resulting in the following fatal defects in blade quality: 1) Decreased static strength: Wrinkle defects reduce the compressive and flexural strength of composite laminates by 30%-50%; laboratory tests on glass fiber composite specimens with wrinkles show that their compressive strength is reduced by an average of about 35% compared to specimens without defects; 2) Sharply reduced fatigue life: Under the same alternating load, the fatigue life of blade structures with obvious wrinkles may only be 10%-30% of that of defect-free components, which is one of the main reasons for premature blade failure.

[0004] Therefore, standards such as the German GL specification and DNV-ST-0376 classify wrinkles as a manufacturing defect that must be strictly controlled in blade production. They typically stipulate that the wrinkle height in critical areas (such as the main beam and the blunt trailing edge) must not exceed 0.5-1 times the skin thickness, and the number of wrinkles per unit area must be strictly controlled. To this end, Chinese patent application number 202223331537.5 discloses a wind turbine blade shell blunt trailing edge fabric layer pressing device. Its base 1 is fixedly installed on the outside of the wind turbine blade shell mold and arranged near the blunt trailing edge. Its support spans both sides of the wind turbine blade shell mold, with its first end fixedly installed on the base. The head of the movable rod is connected to the second end of the support in a manner that is adjustable in both length and angle, and its end is movably connected to an angle-adjustable clamping plate. This solution can prevent the straight-edge fabric layer and core material of the blunt trailing edge wind turbine blade from slipping. However, this process involves pre-fabricating a portion of the blunt trailing edge and then placing it into the main mold for blade forming. This process is prone to deformation and does not fit firmly with the main mold. In addition, the use of molds leads to high production costs, complex processes, and a high product defect rate.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The problem solved by this invention is that the current blade blunt trailing edge region has a weak structure and the fabric and core material are prone to slippage wrinkles, leading to structural failure.

[0007] To solve the above problems, the present invention provides a method for fixing the blunt trailing edge of a blade, comprising: S1, bonding a wooden board to the surface of a mold; S2, fixing the blunt trailing edge fabric layer; S3, fixing the blunt trailing edge core material and sewn fabric; S4, arranging auxiliary materials; S5, assembling and adjusting the clamping fixture; and S6, vacuum tightening.

[0008] This application addresses the method for fixing the fiberglass cloth and core material in the blunt tail edge region. By adjusting the structure, the fiberglass cloth and core material are sewn together and turned out onto the flange for fixation. At the same time, a wooden board is glued to the mold flange to centrally fix the blunt tail edge cloth. After vacuum tightening, the designed tooling is used for external clamping and fixation. Through the tight connection, it is ensured that the blunt tail edge cloth and core material do not slip down, thus achieving design consistency.

[0009] Preferably, step S1 includes: cleaning the mold surface and sanding the rough surface, using a fast adhesive to bond the wooden boards at intervals of 0.8-1.5m to the outer flange platform area of ​​the mold, and allowing them to stand and cure for 3-10 minutes.

[0010] Preferably, step S2 includes: laying fiberglass cloth according to the process, turning the fiberglass cloth outward from the outside of the mold and laying it, and fixing it to the wooden board with steel nails.

[0011] Preferably, step S3 includes: laying the blunt-edged core material according to a preset positioning; overlapping one side of the 300-800mm wide blunt-edged core material sewing cloth with the upper side of the blunt-edged core material by 100-300mm; then fixing it by hand sewing needle and cotton thread through the core material blocks in the overlapping area of ​​the cloth layer; turning the other side out of the flange and fixing it to the fiberglass cloth turned out of the mold with spray glue, and fixing it to another layer of the wooden board with steel nails; then laying the fiberglass cloth again according to the process, turning the fiberglass cloth out of the mold, laying it on another layer of the wooden board and fixing it with steel nails.

[0012] Preferably, step S4 includes: after the blade structure fabric is laid, laying auxiliary materials such as flow guide net and bag membrane, and turning the bag membrane out to the outside of the flange to leave enough slack for vacuum tightening.

[0013] Preferably, step S6 includes: placing the polyurethane board between the bag film and the universal foot cup, pressing the expander, trimming the fiberglass cloth that exceeds the flange, removing the bonded wooden board and laying the vacuuming auxiliary material properly, and then tightening it through the bag film.

[0014] The present invention also provides a wind turbine blade, which is prepared by the above-described method for fixing the blunt trailing edge of the blade.

[0015] Compared with the prior art, the method for fixing the blunt trailing edge of the blade and the wind turbine blade described in this embodiment of the invention have the following beneficial effects:

[0016] 1) By bonding wooden boards and designing tooling to fix the fabric layer flange and suspended core material, the slippage of the fiberglass cloth on the upper and lower parts of the core material is reduced, and the blunt tail edge core material is fixed to the blunt tail edge position, which solves the defect of through wrinkles in the large-blade blunt tail edge structure. This fundamentally reduces the risk of breakage caused by through wrinkles in the blunt tail edge area after the blade is demolded, and has a very high improvement on the reliability of the current large ultra-long flexible blade process.

[0017] 2) This application can effectively reduce the fabric layer wrinkles in the maximum chord length region of the blade, reduce the stress concentration points between the fabric layers and reduce the vertical abrupt change points, so that the force of the fabric layer under different loads can be transmitted normally without local stress abrupt change and expansion, thereby improving the load-bearing capacity and fatigue life of the blade, reducing the abnormal frequency generated by the blade during operation, ensuring power generation efficiency, and reducing the operation and maintenance costs throughout the entire life cycle. Attached Figure Description

[0018] Figure 1 This is a cross-sectional schematic diagram of the ply structure of the blunt trailing edge of the wind turbine blade according to an embodiment of the present invention;

[0019] Figure 2 This is a side view of the leading edge clamping support arm according to an embodiment of the present invention;

[0020] Figure 3 This is a front view of the leading edge clamping support arm according to an embodiment of the present invention.

[0021] Figure 4 This is a first-view view of the leading edge clamping support arm described in an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of the assembly of the steel frame main beam according to an embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram of the structure of the trailing edge support arm according to an embodiment of the present invention;

[0024] Figure 7 This is another perspective view of the trailing edge support arm described in an embodiment of the present invention;

[0025] Figure 8 This is a third-view view of the trailing edge support arm described in an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1-Steel nail; 2-Wooden board; 3-Mold; 4-Bag film; 5-Blunt tail edge core material sewn cloth; 6-Polyurethane board; 7-Blunt tail edge core material; 8-Fiberglass cloth; 9-Tongue pin; 10-Hard nylon pad; 11-Mold limiting plate; 12-Shoulder copper sleeve; 13-First high-strength bolt; 14-Quick clamp; 15-Universal foot cup; 16-Expander; 17-Second high-strength bolt; 18-Clamping flange; 19-Clamping support arm; 20-Rear edge support arm; 21-Steel frame main beam; 22-Flange connecting plate; 23-Support arm flange plate; 24-Support arm steel pipe; 25-Support arm base; 26-Round pipe. Detailed Implementation

[0028] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Without conflict, the technical features of the embodiments of the present invention can be combined with each other.

[0029] Blades are one of the most basic and critical components of wind turbines. To ensure the effective transmission of rigid forces during blade operation and to improve the lift-to-drag ratio of the airfoil, a blunt trailing edge design is usually added to large blades, which means there is a vertical edge at the suction surface. Due to the extreme slope at the blunt trailing edge, soft glass fiber and block core material cannot independently adhere to the vertical edge of the blunt trailing edge, making the layup of the fabric and core material difficult and often resulting in slippage, which seriously affects the quality of the blade.

[0030] The existing blade fabrication process consists of three stages: 1) Layup process: including mold preparation, layer laying, main and auxiliary beam laying, core material laying, layer laying on the core material, flow guiding auxiliary material, and vacuum auxiliary material laying; 2) Infusion process: including resin infusion and resin curing; 3) Mold closing process: including auxiliary material removal, web bonding, mold closing, and spraying after the blade is removed from the mold. The blade blunt trailing edge fixing method described in this application is mainly implemented in the blunt trailing edge region during the layup process, specifically:

[0031] like Figure 1-7 As shown, a method for fixing the blunt trailing edge of a blade includes: S1, bonding a wooden board 2 to the surface of a mold 3; S2, fixing the blunt trailing edge fabric layer; S3, fixing the blunt trailing edge core material and sewn fabric; S4, arranging auxiliary materials; S5, assembling and adjusting the clamping fixture; and S6, vacuum tightening.

[0032] This application roughens the surface of mold 3, uses adhesive to bond wooden board 2 to the outside of the flange of mold 1, and uses steel nails 1 to nail the upper and lower fabric layers 8 of the core material to wooden board 2; at the same time, a separate piece of fiberglass cloth 8 is added to overlap the blunt tail edge core material sewing cloth 5 by 200mm, and the two are sewn together with cotton thread. The blunt tail edge core material 7 is laid according to the preset positioning, and the double-axis cloth is folded and fixed to the wooden block 2; a clamping fixture is used to clamp the rear edge fabric layer area as a whole, increasing the clamping arm length and quick clamping tool to provide sufficient operating space for personnel; the presser foot is equipped with a limit plate to facilitate clamping and aligning the flange of mold 3; the inner side uses universal foot cup 15, and polyurethane board 6 is used to assist in attaching the fabric layer. Weld a large tooling clamping base onto the mold steel frame to support and position the tooling; before trimming the edge of the fabric layer, adjust the vacuum bag film 4 and flip it onto the flange with sufficient width reserved. After clamping the fabric layer with the integrated clamping tool, lift the bag film 4 and place it on the clamping tool arm 19; trim the fabric edge and remove the wooden board 2, then vacuum-tighten the bag film 4 and lift the clamping tool away.

[0033] Preferably, the method for fixing the blunt trailing edge of the blade includes:

[0034] S1. Glue the wooden board 2 onto the surface of mold 3.

[0035] Clean the surface of mold 3 and sand the rough surface. Use quick adhesive to bond the wooden board 2 to the outer flange platform area of ​​mold 3 at 1m intervals. Let it stand and cure for 5 minutes. The thickness of the wooden board is 10mm.

[0036] S2, blunt tail edge fabric layer fixation

[0037] According to the process, fiberglass cloth 8 is laid out, the fiberglass cloth 8 is turned out of the outside of the mold 3 and laid on the wooden board 2. Every 10 layers of fiberglass cloth 8 are fixed to the wooden board 2 with steel nails 1, the length of the steel nails 1 being 10mm.

[0038] S3, blunt trailing edge core material, fixed with sewing cloth

[0039] Lay the blunt-edge core material 7 according to the preset position, prepare a 500mm wide blunt-edge core material sewing cloth 5, one side overlaps the upper side of the blunt-edge core material 7 by 200mm, and use a hand sewing needle and cotton thread to pass through the core material blocks in the overlapping area of ​​the cloth layer to fix it; the other side is turned out of the flange and fixed to the fiberglass cloth 8 turned out to the outside of the mold 3 with spray glue, and fixed to the other layer of the wooden board 2 with steel nails 1.

[0040] Next, fiberglass cloth 8 will be laid again according to the process. The fiberglass cloth 8 will be turned out of the mold 3 and laid on another layer of the wooden board 2. Every 8 layers of fiberglass cloth 8 will be fixed to the wooden board 2 with steel nails 1. The length of the steel nails 1 is 30-40mm.

[0041] S4, Auxiliary Material Arrangement

[0042] After the blade structure layer is laid, the guide net and bag membrane 4 and other auxiliary materials are laid. The bag membrane 4 is turned out to the outside of the flange and the bag membrane 4 is adjusted to leave enough slack for vacuum tightening.

[0043] S5. Assemble and adjust the clamping fixture.

[0044] The clamping fixture, consisting of clamping support arm 19 and trailing edge support arm 20, is assembled onto the steel frame main beam 21, wherein the steel frame main beam 21 is a crossbeam and the blade's blunt trailing edge is not conformal. It should be noted that the welding angle needs to be adjusted during the assembly of the clamping fixture.

[0045] After placing the clamping fixture on the rear edge of the mold, adjust the positioning of the rear edge support arm 20 so that the front edge clamping support arm 19 can effectively attach the fiberglass cloth 8 formed by the blunt tail edge; adjust the direction of the universal foot cup 15 so that the fixture clamps the cloth layer of the blunt tail edge as a whole; after the adjustment is qualified, mark the position of the rear edge support arm 20 corresponding to the outer flange of the mold with a paint pen, and weld the support arm base 25 of the main mold.

[0046] S6, Vacuum Tightening

[0047] Place the polyurethane board 6 between the bag membrane and the universal foot cup 15, press the expander 16 tightly, trim off the fiberglass cloth extending beyond the flange, remove the bonded wooden board, and properly lay the vacuuming auxiliary material. After the bag membrane is tightened, open the clamping fixture to obtain the product. Specifically, after confirming that both the bag membrane and the blade shell are tightened, open the clamping fixture to remove the expander 16 from the product, and use a crane to lift the clamping fixture away.

[0048] This application uses a mold 3 to bond multiple layers of wooden boards 2, fixing the blunt trailing edge core material sewn cloth 5 and fiberglass cloth 8 to the corresponding wooden boards 2. Clamping fixtures are used to fix the blunt trailing edge core material 7, the blunt trailing edge core material sewn cloth 5, and the fiberglass cloth 8 located at the upright edge of the blunt trailing edge. The addition of a polyurethane board 6 increases the stress area and prevents indentations. Afterwards, the wooden boards 2 are removed, ensuring that the core material and cloth layers do not slip before vacuum tightening, significantly improving the reliability of the blunt trailing edge structure production process. Compared to the previous method, this application reduces the frequency of blunt trailing edge wrinkles on the trailing edge of marine blades of 100 meters or more from 70% to 4%, and reduces the defect length of cloth layer wrinkles from a maximum chord length of 20m per blade to 2m, significantly improving blade quality.

[0049] Example 2

[0050] The clamping fixture is mainly composed of three parts: a steel frame main beam 21, a rear edge support arm 20, and a clamping support arm 19. The steel frame main beam 21 is welded from 60×60×5mm steel pipes, and the material requirement is Q355B or above. The steel frame can weigh ≥5t.

[0051] The rear support arm 20 is mainly constructed from 80×80×5mm steel pipes welded together to form a support arm steel pipe 24. A flange connecting plate 22 and a support arm flange plate 23 are welded to the upper side of the support arm steel pipe 24 and fixed to the main steel frame beam 21 using high-strength bolts 13, model M16×120mm. On the lower side of the support arm steel pipe 24, high-strength bolts 13, model M16×120mm, are used to connect it to an 80×5mm round pipe 26. The support base 25 is welded to the steel frame of the main mold 3. When using clamping fixtures, the 80×5mm round pipe 26 is placed in the center of the support base 25 for fixation.

[0052] The clamping support arm 19 is constructed from a main structure welded from 60×60×5mm steel pipes, as shown in Figure 5. The left steel pipe is welded to the main steel beam 21. The right-side fixture is fixed to the left steel pipe by a screw-on mechanism using a shouldered copper sleeve 12 and high-strength bolts 13 (M16×120mm). The clamping flange 18 is welded to the left steel pipe via a steel pipe, and a quick clamp 14 is welded to the clamping flange 18. After the right-side fixture is screwed on, it is tightened using the quick clamp 14 and locked using a tongue pin 9 (M8×100mm). The tongue pin 9 is secured with a chain. A 20mm hard nylon pad 10 is bonded to the contact point between the right-side fixture and the left square steel to prevent damage and deformation.

[0053] Heavy-duty universal foot cup 15, model Φ60, is welded to the left side of expander 16. Expander 16 is welded to square steel of tooling engagement part. Mold limiting plate 11 is clamped in the left square steel area using high-strength bolts 17, model M12×100mm. Adjust the fit between tooling and mold.

[0054] Specifically, the clamping support arm 19 consists of a clamping flange 18 and a quick clamp 14. The clamping part can be rotated up and down to open and close via a shouldered copper sleeve 12 and a first high-strength bolt 13. Preferably, the first high-strength bolt 13 has a size of M16×120mm. The tongue pin 9 and the quick clamp 14 ensure tight clamping of the clamping part. A hard nylon pad 10 is placed at the tooling mating position to prevent deformation of the tooling over time. Preferably, the tongue pin 9 has a size of M8×100mm, and the hard nylon pad 10 has a thickness of 20mm.

[0055] The mold limiting plate 11 is positioned and assembled by a second high-strength bolt 17, the second high-strength bolt 17 being M12×100mm in size. This arrangement ensures that the clamping fixture matches the mold well when fixed, thereby improving the clamping effect. A universal foot cup 15 and a spreader 16 are installed on the front edge of the fixture to ensure that the clamping force and clamping fit can be adjusted during the clamping process; preferably, the universal foot cup 15 is a Φ60 heavy-duty type. The rear edge support arm 20 is based on the support arm steel pipe 24, and the round pipe 26 is connected and fastened on the lower side using a first high-strength bolt 13 and fixed inside the support arm base 25. The support arm base 25 is welded to the outside of the steel frame of the mold 3; a support arm flange plate 23 is welded to the front edge of the support arm steel pipe 24, and the flange connecting plate 22 is fixed to the support arm flange plate 23 using a first high-strength bolt 13, giving it the function of vertical adjustment.

[0056] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for fixing the blunt trailing edge of a blade, characterized in that, include: S1. Glue the wooden board (2) onto the surface of the mold (3); Clean the surface of the mold (3) and sand the rough surface. Use quick adhesive to bond the wooden board (2) to the outer flange platform area of ​​the mold (3) at intervals of 0.8-1.5m. Let it stand and cure for 3-10 minutes. S2, blunt tail edge fabric layer fixation; According to the process, fiberglass cloth (8) is laid out, the fiberglass cloth (8) is turned out of the outside of the mold (3), and laid and fixed on the wooden board (2); S3, blunt trailing edge core material, fixed with sewing cloth; The blunt-edged core material (7) is laid out according to the preset position. One side of the blunt-edged core material sewing cloth (5) with a width of 300-800mm overlaps with the upper side of the blunt-edged core material (7) by 100-300mm. Then, a hand sewing needle and cotton thread are passed through the core material blocks in the overlapping area of ​​the cloth layer to fix it. The other side is turned out of the flange and fixed with spray glue to the fiberglass cloth (8) turned out to the outside of the mold (3), and fixed on another layer of the wooden board (2). Then, according to the process, the fiberglass cloth (8) is laid out again, and the fiberglass cloth (8) is turned out of the outside of the mold (3) and fixed on another layer of the wooden board (2). S4. Arrange auxiliary materials; After the blade structure is laid, the guide net and bag membrane (4) are laid, and the bag membrane (4) is turned out to the outside of the flange so that it leaves enough margin for vacuum tightening; S5. Assemble and debug the clamping fixture; The clamping fixture consisting of the clamping support arm (19) and the trailing edge support arm (20) is assembled onto the steel frame main beam (21), wherein the steel frame main beam (21) is a crossbeam and the blade blunt trailing edge is not conformal; After placing the clamping fixture on the rear edge of the mold, adjust the positioning of the rear edge support arm (20) so that the front edge clamping support arm (19) can effectively attach the fiberglass cloth (8) forming the blunt tail edge; adjust the direction of the universal foot cup (15) so that the fixture clamps the cloth layer of the blunt tail edge as a whole; after the adjustment is qualified, mark the position of the rear edge support arm (20) corresponding to the outer flange of the mold with a paint pen, and weld the support arm base (25) of the main mold. S6. Vacuum tightening; Place the polyurethane board (6) between the bag film (4) and the universal foot cup (15), press the expander (16) tightly, trim off the fiberglass cloth (8) that extends beyond the flange, remove the glued wooden board (2), and lay the vacuuming auxiliary material properly. Then, tighten the vacuuming through the bag film (4).

2. A wind turbine blade, characterized in that, The blade is prepared by the method for fixing the blunt trailing edge as described in claim 1.

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