Maintenance process suitable for wind power blade sandwich structure

Abstract

The invention discloses a maintenance process suitable for a sandwich structure of a wind power blade, which comprises the following steps of: removing a defective area of the blade, and performing regular rectangular shape modification on the defective area; a glue injection side and an air exhaust side are determined, a lower cloth liner, a core material and an upper cloth liner are sequentially laid in the defect area from bottom to top, and demolding cloth, isolation cloth and a flow guide net are laid on the upper cloth liner; arranging a glue injection pipeline and an air exhaust pipeline, wherein the air exhaust pipeline adopts a spiral pipe air exhaust strip wrapped by a VAP film; after a vacuum film is arranged, vacuumizing and pressure maintaining are qualified, pouring operation is carried out, heating curing is carried out after pouring, and maintenance is completed; the method for maintaining the cloth liner under the core material is adopted, the three edges of the cloth liner are equal to the core material in height, and one edge of the glue injection side is turned out of the outer surface of the core material by 2-5 cm to be used for resin drainage in the pouring process; a manufacturing method of a spiral pipe air exhaust strip sealing unit with the air exhaust side of a cloth liner core material on a blade core material wrapped by VAP is adopted, the distance between the spiral pipe air exhaust strip sealing unit and the edge of a flow guide net on the air exhaust side is limited to be within the range of 3-7 cm, and the maintenance and pouring quality is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine blade maintenance, and particularly relates to a maintenance process applicable to the sandwich structure of wind power blades. Background Art

[0002] Wind energy has become one of the new energy sources with the most development potential due to its excellent characteristics of green energy, and has been widely used and vigorously developed. As one of the most core components of a wind turbine, the design quality and manufacturing quality of wind turbine blades are the prerequisites for the stable and efficient operation of the unit.

[0003] In recent years, affected by the cost reduction pressure of the entire wind power industry, the design margin of wind turbine blades has become weaker and weaker. Coupled with the impact of the rush installation period, the production quality of wind turbine blades will decline significantly during the rush installation period. As a result, quality accidents of operating blades in wind farms have occurred frequently in recent years, and there are more and more problems of on-site blade failure. As one of the main structures of wind turbine blades, the damage of the sandwich structure is also one of the main forms of on-site blade failure in recent years.

[0004] In the entire structure of the blade, except for the root region, main beam region, secondary beam region, and front and rear edge mold joint regions, the rest of the regions are sandwich structure regions, and their proportion in the total blade area is generally not less than 70%. Therefore, it further shows that the failure of the sandwich region is one of the main forms of blade failure. The failure of the blade sandwich region is generally accompanied by structural damages such as delamination, bulging, and cracking. And structural damages generally involve the replacement of the core material and re-infusion. Although in recent years, the core material repair in the sandwich region of the blade has been improved from the original hand lay-up process to the infusion process, due to the over-ideal process plan of the current infusion process, the achieved effect is not good. The reason is that core material infusion needs to fully consider the impregnation speed of the upper and lower surfaces of the core material and the resin infiltration speed from top to bottom around the prefabricated cut blocks of the core material. It has relatively high requirements for the environmental conditions for carrying out the infusion process. For example, it is necessary to have suitable environmental temperature and humidity to control the viscosity of the infusion resin, etc. However, the environmental conditions are relatively poor during the actual on-site implementation process. As a result, the infusion quality of the lower interface of the lower core material is very unstable, and rework occurs frequently, thus causing a large amount of waste of manpower and material resources. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention provides a maintenance process applicable to the sandwich structure of wind turbine blades, which can realize the maintenance of wind turbine blades with sandwich structures, can improve the overall infusion quality by continuously evacuating air during the infusion and curing processes in the maintenance area, and thus improve the maintenance quality.

[0006] The technical solution of the present invention is as follows:

[0007] In the first aspect of the present invention, a maintenance process applicable to the sandwich structure of wind turbine blades is provided, including the following steps:

[0008] Step 1: Remove the area with defects on the blade and perform regular rectangular shaping on the defect area.

[0009] Step 2: Determine the glue injection side and the air extraction side. Lay the lower backing cloth, core material, and upper backing cloth on the defect area in sequence from bottom to top. Lay the release cloth, isolation cloth, and flow guiding net on the upper backing cloth.

[0010] Step 3: Arrange the glue injection pipeline and the air extraction pipeline. The air extraction pipeline uses a spiral air extraction strip wrapped with VAP film.

[0011] Step 4: After arranging the vacuum film to evacuate and maintain pressure to meet the requirements, perform the perfusion operation. After perfusion, perform heating and curing to complete the repair.

[0012] In some embodiments of the present invention, in Step 1, after performing rectangular shaping, perform cleaning. If the outer skin of the blade in the corresponding area is damaged after cleaning, use hand-laid fiberglass cloth to perform hand-laid sealing treatment on the damaged position of the outer skin area, paste the release cloth, find and repair, polish the bright surface after curing, and perform cleaning again.

[0013] In some embodiments of the present invention, when laying the lower backing cloth, one side of the lower backing cloth extends 2 - 5 cm out of the inner skin area along the vertical surface of the rectangular area, and the other three sides are closely attached to the vertical surface of the core material rectangular area and are flush with the surface of the inner skin.

[0014] In some embodiments of the present invention, the glue injection pipeline is arranged in the area where the lower backing cloth extends out of the inner skin. The glue injection pipeline is arranged on the side opposite to the air extraction pipeline, and the glue injection pipeline is arranged parallel to the air extraction pipeline.

[0015] In some embodiments of the present invention, the glue injection pipeline and the air extraction pipeline are arranged opposite to each other, and the air extraction pipeline maintains a distance of 3 - 7 cm from the flow guiding net.

[0016] In some embodiments of the present invention, the preparation process of the spiral air extraction strip wrapped with VAP film is as follows:

[0017] Cut the VAP film into strip shapes, and the length of the VAP film is equal to the length of the defect area.

[0018] Place the hollow spiral tube in the length direction of the VAP film, then fold the VAP film along the width direction and seal it with black rubber strips.

[0019] Connect both ends of the hollow spiral tube to the vacuum extraction tube, and seal both ends of the VAP film with black rubber strips to form a sealed vacuum extraction space inside the VAP film.

[0020] In some embodiments of the present invention, the width of the VAP film is 7 - 9 cm.

[0021] In some embodiments of the present invention, both the lower backing cloth and the lower backing cloth are made of biaxial fiberglass fabric, and 1-2 layers of the biaxial fiberglass fabric are laid.

[0022] In some embodiments of the present invention, the size of the upper backing cloth is the same as that of the replacement core material.

[0023] In some embodiments of the present invention, when heating and curing in step four, a heating blanket is used to cover the upper part of the repair area for heating and curing.

[0024] One or more technical solutions of the present invention have the following beneficial effects:

[0025] (1) The repair process applicable to the sandwich structure of wind turbine blades provided by the present invention trims the damaged area of the blade into a rectangle. When laying the lower backing cloth, the size of the backing cloth is equal to the height of the core material on three sides, and one side on the resin injection side is turned out 2-5 cm outside the outer surface of the core material for resin drainage during the perfusion process, ensuring that resin drainage can be achieved during the perfusion process to improve the perfusion effect on the lower surface; at the same time, laying a biaxial fiberglass fabric on the core material, and the size of the backing cloth is the same as that of the replacement core material, which can improve the resin infiltration on the upper surface of the core material, and further avoid problems such as pits on the upper surface of the core material replacement area after the repair is completed.

[0026] (2) The present invention uses a VAP-wrapped spiral tube air extraction strip sealing unit as an alternative air extraction pipeline, and at the same time limits the distance between the air extraction strip and the edge of the air extraction side guide net to 3-7 cm, which can achieve continuous air extraction during the perfusion and curing processes of the repair area to improve the overall perfusion quality, and can prevent the resin from being sucked away during the air extraction process, resulting in poor glue and whitening in the area near the air extraction pipeline. Description of the Drawings

[0027] Figure 1 Is the actual state after grinding and removing the core material in the damaged area of the blade core material structure;

[0028] Figure 2 Is a schematic diagram after laying the lower backing cloth;

[0029] Figure 3 Is a schematic diagram of the layout of the upper backing cloth, auxiliary materials and VAP-wrapped spiral tube air extraction strip on the core material;

[0030] Figure 4 Is a schematic diagram of the VAP film-wrapped spiral tube air extraction strip.

[0031] In the figure: 1. Glue injection pipeline; 2. Guide net; 3. Lower backing cloth; 4. Upper backing cloth; 5. Core material for repair and replacement; 6. Air extraction strip; 7. Spiral tube; 8. VAP film; 9. Black glue strip. Detailed Embodiments

[0032] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] Embodiment 1

[0034] In a typical implementation manner of the present invention, a maintenance process applicable to the sandwich structure of wind turbine blades is proposed. As Figures 1-3 shown, it includes the following steps:

[0035] Step 1: Clear the defective area of the blade and perform a regular rectangular shaping on the defective area.

[0036] Specifically, first, thoroughly remove the original core material structure in the area with core material breakage, cracking, and delamination as the defective damage area. After removing the core material, use a angle grinder to clean the core material debris adhered to the inner side of the outer skin, and perform a regular rectangular shaping on the four sides of the removed core material area. When grinding, it is necessary to ensure that the vertical surfaces around the replaced and removed core material are vertical to facilitate the filling of the core material during the maintenance process.

[0037] Furthermore, after the rectangular shaping, perform cleaning. If there is damage to the outer skin of the blade in the corresponding area after cleaning, use hand-laid fiberglass cloth to perform hand-laid sealing treatment on the damaged position of the outer skin area, paste the release cloth, and after curing, patch and polish the bright surface and clean again.

[0038] Step 2: Determine the glue injection side and the air extraction side, and sequentially lay the lower backing cloth 3, the repaired and replaced core material 5, and the upper backing cloth 4 from bottom to top in the defective area. Lay the release cloth, isolation cloth, and flow guiding net 2 on the upper backing cloth.

[0039] When laying the lower backing cloth, one side of the lower backing cloth extends 2 - 5 cm out of the inner skin area along the vertical surface of the rectangular area, and the other three sides are closely attached to the vertical surface of the core material rectangular area and flush with the surface of the inner skin. Both the lower backing cloth and the lower backing cloth are made of biaxial fiberglass fabric, and 1 - 2 layers of the biaxial fiberglass fabric are laid.

[0040] Specifically, in the core material removal area, first lay one or two layers of biaxial fiberglass fabric as the core material lower backing cloth, lay the fiberglass smoothly and make the corner areas stick firmly. Plan the glue injection side and the air extraction side in advance. Along the vertical surface on one side of the glue injection pipe, extend 2 - 5 cm out of the inner skin area, and the other three sides are closely attached to the vertical surface of the core material rectangular area and flush with the surface of the inner skin. Then, cut the core material plate according to the actual rectangular size of the removal area and lay it in this area. The thickness of the core material should not be higher than other areas. Then, lay 1 - 2 layers of biaxial fiberglass fabric on the upper surface of the core material as the core material upper backing cloth, and then start laying the original structural cloth layer on the normal core material. Immediately arrange auxiliary materials such as the release cloth, isolation film, and flow guiding net, and arrange the glue injection pipe outside the side where the core material lower backing cloth extends.

[0041] Step 3: Arrange the glue injection pipeline 1 and the air extraction pipeline. The air extraction pipeline uses a spiral air extraction strip wrapped with VAP film. Further, when laying the underlay cloth, the glue injection pipeline is arranged in the area where the underlay cloth extends beyond the inner skin, and the glue injection pipeline is arranged on one side opposite to the air extraction pipeline, and the glue injection pipeline is arranged parallel to the air extraction pipeline.

[0042] Further, the glue injection pipeline 1 and the air extraction pipeline are arranged opposite to each other, and the air extraction pipeline is kept at a distance of 3 - 7 cm from the diversion net.

[0043] Specifically, the air extraction pipeline uses a spiral air extraction strip 6 wrapped with VAP film, which is arranged on the opposite side of the glue injection pipeline and kept at a distance of 3 - 7 cm from the diversion net. In this way, no resin will be extracted during the perfusion and curing processes, and the problem of poor glue and whitening caused by air extraction at the cloth edge can be avoided.

[0044] Step 4: After arranging the vacuum film and performing vacuum pumping and pressure holding to be qualified, perform the perfusion operation. After perfusion, perform heating and curing to complete the repair.

[0045] Specifically, after arranging the vacuum film and performing vacuum pumping and pressure holding to be qualified, perform the normal perfusion operation. After perfusion, turn on the heating blanket and perform heating and curing according to the set program. In this way, problems such as infiltration and wrapping, poor infiltration, and whitening can be largely avoided at the upper and lower interfaces of the core material, especially at the lower interface of the core material after curing, and the repair qualification rate can be greatly improved.

[0046] In this embodiment, the preparation process of the spiral air extraction strip wrapped with VAP film is as follows, and the schematic diagram is as Figure 4 shown:

[0047] Cut the VAP film into strip shapes, and the length of the VAP film is equal to the length of the defective area;

[0048] Place the hollow spiral tube in the length direction of the VAP film, then fold the VAP film along the width direction and seal it with a black rubber strip;

[0049] Connect both ends of the hollow spiral tube to the vacuum extraction pipe, and seal both ends of the VAP film with a black rubber strip to form a sealed vacuum extraction space inside the VAP film.

[0050] In this embodiment, the width of the VAP film is 7 - 9 cm.

[0051] In a specific implementation manner of this embodiment, the air extraction strip is prepared in the following manner:

[0052] (1) Cut the VAP film into strip shapes about 8 cm wide, and the length is equal to the actual length of the repair area of the sandwich structure;

[0053] (2) For the cut VAP film, paste a sealed black glue along one side of the entire length direction along the edge of the VAP film, place one or two equally long hollow spiral tubes in the middle, then remove the sealed black glue paper skin (the bonding isolation protection skin on the upper surface), fold the other side of the cut VAP film in half along the width direction of the other side and paste it on the black glue strip on the other side. Insert the extraction vacuum tubes into the spiral tube heads at both ends in the length direction, paste black glue strips at the edges of the VAP air extraction strips at both ends to seal both ends together with the extraction vacuum tubes, and connect the external vacuum pump pipelines to the extraction vacuum tubes at both ends. In this way, an air extraction strip that conducts air but not glue is made.

[0054] During vacuum extraction, under the action of the vacuum pump, the air in the area to be vacuumed below the vacuum film enters the hollow spiral tube through the VAP film, and then enters the extraction vacuum tube, realizing the vacuum extraction process. After the vacuum pressure holding is qualified, normal perfusion operation is carried out. At the same time, since the air extraction strip and the diversion net maintain a distance of 3 - 7 cm, no resin will be extracted during the perfusion and curing processes, and the problem of poor glue and whitening caused by air extraction at the cloth edge can be avoided.

[0055] The maintenance method provided in this embodiment can significantly improve the perfusion maintenance quality. When replacing the core material in the damaged area of the core material, it is mainly polished and cleaned according to the requirements of rectangle and vertical surface flatness. Before laying the core material, double-axis fiberglass fabric is padded for the lower 1 - 2 layers of the core material. The three sides of the padding cloth are as high as the thickness of the core material, and the other side is turned out 2 - 5 cm from the core material surface on the perfusion side to ensure that resin drainage can be achieved during the perfusion process, thereby improving the perfusion effect on the lower surface. Padding the double-axis fiberglass fabric on the core material can solve problems such as pits on the upper surface of the core material replacement area after maintenance. The spiral tube air extraction strip sealing unit wrapped by VAP can be used as an alternative air extraction pipeline, which can achieve permanent air extraction during the perfusion and curing processes in the maintenance area to improve the overall perfusion quality, and can prevent poor glue and whitening in the area near the air extraction pipeline caused by the resin being sucked away during the air extraction process. At the same time, compared with the prefabricated fixed-width VAP air extraction belt currently in use, it can solve the problem that the VAP air extraction belt cannot be arranged in a narrow space, and the air extraction suction of the VAP air extraction strip will also be significantly increased, and the gas discharge effect in the perfusion maintenance area is better. Overall, the entire process can significantly improve the stability of the perfusion maintenance quality of the sandwich structure.

[0056] Although the specific implementation manners of the present invention are described above in conjunction with the drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. A maintenance process for a wind turbine blade sandwich structure, characterized in that: The following steps are involved: Step 1: Clear the defective area of ​​the blade and shape the defective area into a regular rectangular shape; Step 2: Determine the injection side and the exhaust side, lay the lower pad, core material and upper pad in the defect area from bottom to top, and lay the release cloth, isolation cloth and guide net on the upper pad; Step 3: Arrange the glue injection pipeline and the air extraction pipeline, wherein the air extraction pipeline adopts a spiral tube air extraction strip wrapped with a VAP film; Step 4: After the vacuum membrane is arranged and the vacuum pressure is maintained, the infusion operation is carried out. After the infusion, it is heated and cured to complete the maintenance.

2. The repair process for a wind turbine blade sandwich structure according to claim 1, characterized in that: In the step 1, the rectangular shaping is performed and then cleaning is performed. After cleaning, if the outer skin of the blade in the corresponding area is damaged, the damaged position of the outer skin area is sealed by hand-laid fiberglass cloth, and a release cloth is pasted. After curing, the bright surface is polished and cleaned again.

3. The repair process for a wind turbine blade sandwich structure according to claim 1, characterized in that: When laying the lower cloth, one side of the lower cloth is laid out 2-5 cm from the inner skin area along the vertical surface of the rectangular area, and the other three sides are closely attached to the vertical surface of the core material rectangular area and flush with the surface of the inner skin.

4. The repair process for a wind turbine blade sandwich structure as claimed in claim 3, characterized in that: The glue injection pipeline is arranged in the area where the lower cloth is laid out to form the inner skin, and the glue injection pipeline is arranged on the side opposite to the air extraction pipeline, and the glue injection pipeline is arranged in parallel with the air extraction pipeline.

5. The repair process for a wind turbine blade sandwich structure as claimed in claim 4, characterized in that: The glue injection pipeline and the air extraction pipeline are arranged opposite to each other, and the air extraction pipeline maintains a distance of 3-7 cm from the guide net.

6. The repair process for a wind turbine blade sandwich structure according to claim 1, characterized in that: The preparation process of the spiral tube vacuum strip wrapped with the VAP film is as follows: Cut the VAP film into strips, with the length of the VAP film being equal to the length of the defective area; Place a hollow spiral tube in the length direction of the VAP film, then fold the VAP film in half along the width direction and seal it with a black tape; The two ends of the hollow spiral tube are connected to the vacuum tube, and the two ends of the VAP film are sealed with black tape to form a sealed vacuum space inside the VAP film.

7. The repair process for a wind turbine blade sandwich structure according to claim 6, characterized in that: The width of the VAP film is 7-9 cm.

8. The repair process for a wind turbine blade sandwich structure according to claim 1, characterized in that: The bottom cloth and the bottom cloth are both made of biaxial glass fiber fabric, and the biaxial glass fiber fabric is laid in 1-2 layers.

9. The repair process for a wind turbine blade sandwich structure according to claim 1, characterized in that: The size of the upper pad is the same as that of the replacement core material.

10. The repair process for a wind turbine blade sandwich structure according to claim 1, characterized in that: When heating and curing is performed in step 4, a heating blanket is used to cover the top of the maintenance area for heating and curing.

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