Method for solving wind power blade solidification crazing whitening problem

Abstract

The invention relates to the technical field of non-metal composite material mold forming processes, in particular to a method for solving the problem of wind power blade curing crazing whitening, and the method comprises the following specific steps: S1, region division; independently connecting a heating device according to the crazing generation area; s2, laying a cloth layer and a flow guide structure; s3, heating and curing the half blade; after the curing procedure is started, all the areas are heated at the fixed temperature in a stepped mode, and it is guaranteed that all the areas are synchronously heated; s4, closing the mold; s5, heating and curing the blade; gradient heating is adopted for heating, and the heating temperature is smaller than the TG value of the product; and S6, checking. According to the method, through temperature design of pouring curing and mold closing curing and heating partition of independent partition crazing whitening, the influence on partitions with different thicknesses is reduced, the heat release peak-to-peak value during curing is reduced, the phenomenon of resin implosion caused by heat release accumulation of a product is avoided, the problem of crazing whitening is prevented, and the blade forming quality is improved.

Description

Technical Field

[0001] The invention relates to the technical field of non-metal composite material mold forming technology, and in particular to a method for solving the problem of silver streaks and whitening during the curing of wind turbine blades. Background Art

[0002] The conventional gradient heating curve scheme used in the curing process of wind turbine blades is shown in the figure below. A single heating curve is used during the product infusion process, and a heating curve is used as a whole during the product bonding process. This makes it impossible for the product to accumulate heat during the heat release process according to the material properties of the product itself and the changes in the external ambient temperature, resulting in resin explosion and silver streaks. At the same time, due to the complex and uneven structure of the blade itself, the resin infiltration is uneven, resulting in silver streaks caused by asynchronous heat release, thereby increasing maintenance costs, not conducive to improving the safety of the blade structure, and extending the blade post-processing cycle.

[0003] The existing blade curing process mostly solves the silver streak problem from the blade structure itself. Publication number: CN118438699A discloses a processing method for the blade root structure of a wind turbine blade. The UD rod, PET rod and screw sleeve in the traditional blade root structure are replaced by a pultruded screw sleeve assembly. The screw sleeve assembly is laid in parallel in the blade root mold and formed integrally with the shell, eliminating the process of prefabricating the blade root. The one-time molding of the blade root can effectively reduce the silver streak. However, this application only solves the silver streak problem at the root of the blade, and cannot solve the silver streak problem in other areas of the blade. Publication number: CN117124618A discloses a device and method for preparing a prefabricated blade root for a wind turbine blade. The convex surface structure can not only effectively prevent the fiber braid from sliding down, without the need to use spray glue for fixing, but also because of the gravity of the fiber braid itself, it can be effectively spread along the convex surface structure, reducing the frequency of wrinkles in the area of ​​more fiber braids, and the prepared prefabricated blade root has fewer defects and better interlayer performance. However, the technical solution of this application cannot solve the silver streak problem caused by different resin curing time.

[0004] Therefore, there is an urgent need for a method to solve the problem of silver streaks and whitening during the curing of wind turbine blades, so as to improve the quality of blade molding, reduce maintenance costs, increase blade structural safety, and speed up the blade post-processing cycle. Summary of the invention

[0005] In view of this, the present invention aims to propose a method for solving the problem of silver streaks and whitening during the curing of wind turbine blades, so as to solve the problem of silver streaks and whitening after the production of wind turbine blades, improve the molding quality of blades, reduce maintenance costs, increase the safety of blade structures, and accelerate the post-processing cycle of blades.

[0006] Due to the differences in product layer structure, preform position, and resin infiltration time (opening the tube prematurely before the infusion is completed), the time and peak value of the exothermic peaks generated by different materials and thicknesses are different during the actual heating process, resulting in asynchronous heat release in different areas, generating stress and forming silver streaks and whitening defects.

[0007] The present invention adjusts the curing system to a gradient temperature increase. At the beginning of the curing process, all areas are heated at a low temperature. Within a period of time, all areas of the product reach the same temperature. The first temperature increase is performed to ensure that all areas are heated synchronously. At the same time, for areas with uneven structures or slow heating and late exothermic peaks, the second temperature increase is performed. At this time, all areas can reach the exothermic state or the exothermic peak. At the same time, low-temperature curing can also reduce the exothermic peak of the product, so that the exotherm of the product is not too intense.

[0008] During the mold closing and heating process, the mold heats up rapidly, resulting in excessive thickness difference in the silver streak area, uneven shrinkage and stress. When the mold is closed and heated for curing, the mold heating temperature exceeds the TG value of the product, and the FRP product changes from a highly elastic state to a glassy state. Since the FRP resin has been infiltrated and cured, the resin will not infiltrate after it is converted to a glassy state again, resulting in silver streaks.

[0009] During the secondary heating process of the mold, the temperature can be slowly increased, and a gradient temperature increase can be set. For thicker blade root areas, silver streaks are prone to appear. The heating temperature is 15-20°C lower than the TG value of the heating area. According to the secondary heating temperature data of each base, the critical temperature for the secondary generation of silver streaks can be completely eliminated at 40-50°C. When solving the silver streak problem, the secondary heating temperature of the silver streak generation area can be set at 40-50°C. Reduce the need to measure the TG value of the adhesive in this area after secondary heating.

[0010] In view of the above situation, a set of methods is provided. First, in the area where the silver streaks appear, the uneven structure of the cloth layer is analyzed during the plying process, and a guide medium is added in the middle of the cloth layer to increase the uniformity of the product infusion and curing; secondly, the product curing system is started after the infusion is completed, the purpose of which is to ensure that the initial temperature of all resin heat release in the product is consistent; then the curing system is set to a gradient temperature increase to ensure that all areas of the product release heat evenly and gradually, and to ensure that the product passes the exothermic peak at a low temperature. Finally, in the secondary heating of the blade mold, the silver streak whitening area is separated separately, and low-temperature curing heating is set, that is, the temperature is set to a temperature 15-20℃ lower than the TG value of the product.

[0011] The technical solution of the present invention is implemented as follows: A method for solving the problem of silver streaks and whitening during the curing of wind turbine blades comprises the following specific steps:

[0012] S1: Area division: according to the silver streak occurrence area, the silver streak whitening area in the blade forming mold is divided into separate areas and connected to an independent heating device;

[0013] S2: Laying the fabric layer and the diversion structure; adjusting the fabric layer structure in the area where silver streaks occur, adjusting the uniformity of the perfusion diversion, and controlling the fat injection content in the area;

[0014] S3: Half blade is heated and cured; gradient heating is used during vacuum infusion, and all areas are heated at a fixed temperature in steps after the curing process begins to ensure that all areas are heated synchronously;

[0015] S4: mold closing;

[0016] S5: Blade heating and curing; heating is performed by gradient heating, and the heating temperature is lower than the TG value of the product;

[0017] S6: Inspection: whether there are silver streaks on the leaves according to the method of judging whether the silver streaks are white.

[0018] Further, in step S1, the silver streak occurrence area includes the blade root, the trailing edge UD, and the vertical surface area.

[0019] Furthermore, in step S2, the step of adjusting the uniformity of the infusion diversion includes: adding continuous felt in the small belly plate reinforcement area, and / or, canceling the cloth layer under the core rod, adjusting the size of the core rod, and / or, canceling the cloth layer at the end position of the UD rod or adding continuous felt under the pressure plate.

[0020] Further, in step S3, the step-fixed temperature heating includes at least two heatings.

[0021] Further, in step S3, the step-fixed temperature heating includes a first heating, a second heating and a third heating.

[0022] Further, in step S3, the first heating temperature is set to 35-55°C, the curing time is set to 1-3.5h, the second heating temperature is set to 35-65°C, the second heating time is set to 0.5-2.5h, and the third heating is set to 60-85°C until curing.

[0023] Furthermore, in step S3, the heating curve of the root preform and the shell root is as follows: first, the root preform and the shell root are heated to 50°C within 30 minutes, then kept warm for 90 minutes, then heated to 60°C within 20 minutes, kept warm for 90 minutes, and finally heated to 70°C within 10 minutes, and kept warm for 180 minutes.

[0024] Furthermore, in step S3, the heating curve of the trailing edge facade is as follows: first, the trailing edge facade with a preheating temperature of 35°C is heated to 40°C within 10 minutes, and then kept warm for 90 minutes, then heated to 45°C within 10 minutes, kept warm for 60 minutes, then heated to 50°C within 10 minutes, kept warm for 60 minutes, and finally heated to 75°C within 50 minutes, and kept warm for 70 minutes.

[0025] Further, in step S3, the UD preform heating curve is as follows: first, the UD preform with a preheating temperature of 35°C is heated to 40°C within 10 minutes, and then kept warm for 120 minutes, then heated to 45°C within 10 minutes, kept warm for 50 minutes, then heated to 50°C within 10 minutes, kept warm for 60 minutes, and finally heated to 75°C within 50 minutes, and kept warm for 50 minutes.

[0026] Further, in step S5, the blade heating curing curve is as follows: first, the molded blade preheated at 40°C is kept warm for 60 minutes, then the temperature is raised to 50°C within 20 minutes and kept warm for 280 minutes.

[0027] Compared with the prior art, the method for solving the problem of silver streaks and whitening during the curing of wind turbine blades of the present invention has the following advantages:

[0028] 1. The present invention designs the temperature of infusion curing and mold curing, and separately zones the heating zones for silver streaks and whitening, thereby reducing the impact on zones of different thicknesses, reducing the peak value of heat release during curing, avoiding the accumulation of heat release from the product causing resin explosion, preventing the problem of silver streaks and whitening, improving the quality of blade molding, avoiding later maintenance, reducing maintenance costs, shortening the circulation cycle, and increasing the safety of the blade structure.

[0029] 2. The present invention optimizes and adjusts the uneven cloth layer structure to ensure that the curing reaction in each area is carried out synchronously, avoiding uneven resin infiltration caused by the complex and uneven structure of the blade, resulting in asynchronous heat release and thus silver streaks. This helps to improve the quality of blade molding, avoid later maintenance, reduce maintenance costs, shorten the circulation cycle, and increase the safety of the blade structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0031] Figure 1 This is a schematic diagram of heating zones in the silver streak region of the present invention;

[0032] Figure 2 The heating curve of the root prefabricated part and the shell root in the present invention;

[0033] Figure 3 is the rear edge elevation heating curve in the present invention;

[0034] Figure 4 is the heating curve of the UD preform in the present invention;

[0035] Figure 5 The blade heating and curing heating curve in the present invention;

[0036] Figure 6 For the dead whitening of the package before baking;

[0037] Figure 7 After baking, the buns turn white.

[0038] Description of reference numerals:

[0039] 1. Root area; 2. Rear edge facade area; 3. UD prefabricated part area. DETAILED DESCRIPTION

[0040] In order to make the technical means, objectives and effects of the present invention easy to understand, the embodiments of the present invention are described in detail below with reference to specific drawings.

[0041] It should be noted that all the terms used in the present invention to indicate directionality and position, such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "top", "lower", "lateral", "longitudinal", "center", etc., are only used to explain the relative positional relationship and connection status between the components in a certain state, and are only for the convenience of describing the present invention, rather than requiring the present invention to be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0042] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0044] Silver streaks generally refer to tiny and dense cracks that appear on the surface or inside glassy polymers or certain semi-crystalline polymers and epoxy resins due to stress or environmental factors. The cross-section of these microcracks can cause total reflection of light, resulting in a silver flash, hence the name silver streaks.

[0045] The epoxy resin curing process is an exothermic process. As the curing behavior occurs, the heat generated by the curing accumulates and causes the resin temperature to increase. The resin temperature measured when the heat reaches the peak value is called the exothermic peak temperature, and the time for the resin curing to reach the exothermic peak is generally used to measure the degree of the curing reaction.

[0046] The curing process of epoxy resin is divided into three states: viscous state (liquid state), highly elastic state (gel state), and glassy state. The temperature at which the glassy state is transformed into the highly elastic state is called the glass transition temperature TG.

[0047] The present invention discloses a method for solving the problem of silver streaks and whitening during the curing of wind turbine blades, comprising the following specific steps:

[0048] S1: Area division: according to the silver streak occurrence area, the silver streak whitening area in the blade forming mold is divided into separate areas and connected to an independent heating device;

[0049] S2: Laying the fabric layer and the diversion structure; adjusting the fabric layer structure in the area where silver streaks occur, adjusting the uniformity of the perfusion diversion, and controlling the fat injection content in the area;

[0050] S3: Half blade is heated and cured; gradient heating is used during vacuum infusion, and all areas are heated at a fixed temperature in steps after the curing process begins to ensure that all areas are heated synchronously;

[0051] S4: mold closing;

[0052] S5: Blade heating and curing; heating is performed by gradient heating, and the heating temperature is lower than the TG value of the product;

[0053] S6: Inspection: whether there are silver streaks on the leaves according to the method of judging whether the silver streaks are white.

[0054] By accurately identifying the specific area where silver streaks occur, more targeted treatment can be carried out to avoid indiscriminate adjustments to the entire blade, thereby improving the efficiency and accuracy of problem solving; setting up a separate heating device provides a physical basis for the subsequent adoption of differentiated heating strategies, making the treatment measures more flexible and effective; adjusting and eliminating abnormal cloth layers can effectively reduce or avoid stress concentration and poor resin flow caused by unreasonable cloth layer structure, and can prevent the occurrence of silver streaks; optimizing the guide structure can better control the flow and distribution of resin, ensure that the resin evenly and fully infiltrates the reinforcing material in all parts of the blade, and improve the quality and performance of blade molding; by controlling the amount of fat injected in the area, the problem of silver streaks caused by too little or too much resin can be avoided; through the heating process of the blade half and after mold closing, a gradient heating strategy is adopted, and all areas are heated synchronously, which can reduce the problem gradient inside the blade, reduce the thermal stress caused by temperature difference, and thus reduce the risk of silver streaks; according to the judgment method of silver streak whitening, the blade is inspected, and the problem is discovered and solved in time to ensure the factory treatment of the blade.

[0055] This process method effectively prevents and solves the problem of silver streaks and whitening on blades through steps such as area division, optimization of cloth layers and guide structures, differentiated heating and curing, and strict inspection, thereby improving the molding quality and performance of the blades.

[0056] Specifically, in step S1, the silver streak occurrence area includes the blade root, the trailing edge UD, and the vertical surface area.

[0057] The blade root, trailing edge UD and vertical area are common stress concentration areas in wind turbine blades, which are prone to silver streaks. Clarifying the specific locations where silver streaks occur can facilitate the formulation of corresponding heating and curing strategies and process parameters based on the characteristics of different areas, ensuring that each area can receive the most appropriate treatment, thereby reducing the occurrence of silver streaks and improving processing efficiency.

[0058] This setting can accurately distinguish the area where silver streaks occur, making it convenient for a separate heating device to take refined heating control over the area where silver streaks occur, reducing the risk of silver streaks occurring, improving the overall quality of the blade, reducing the difficulty of control, shortening the blade production cycle, and improving production efficiency.

[0059] Specifically, in step S2, the step of adjusting the uniformity of the perfusion diversion includes: adding continuous felt in the small belly plate reinforcement area, and / or, canceling the cloth layer under the core rod, adjusting the size of the core rod, and / or, canceling the cloth layer at the end position of the UD rod or adding continuous felt under the pressure plate.

[0060] Adding continuous felt in the small belly plate reinforcement area can effectively improve the strength and stiffness of the local area of ​​the blade, reduce the occurrence of silver streaks caused by stress concentration, and significantly improve its stress performance; canceling the layout under the core rod helps to reduce the flow resistance of the resin in this area, allowing the resin to penetrate and infiltrate the reinforcing material more smoothly, avoiding the formation of holes or dry spots due to poor resin flow, thereby reducing the possibility of silver streaks; according to the specific structural requirements and stress distribution of the blade, the size of the core rod is reasonably adjusted to help better distribute and transfer the load; canceling the cloth layer at the end position of the UD rod or adding a continuous felt under the pressure plate to improve the bonding between the UD rod and the surrounding laminated structure and increase the interlaminar shear strength and peel strength.

[0061] This setting can reduce the occurrence of defects such as silver streaks by optimizing the cloth layer structure and adjusting the core rod layout, improve the molding quality and overall performance of the blades, help improve the durability and fatigue resistance of the blades, thereby extending the service life of the blades, reducing the risk of scratches or damage in severe weather or extreme working conditions, and improving the safety performance of wind turbines.

[0062] Specifically, in step S3, the step-fixed temperature heating includes at least two heatings.

[0063] Preferably, the step-fixed temperature heating includes a first heating, a second heating and a third heating.

[0064] The purpose of the first heating is to preheat the material, so that the compression material gradually heats up and reduces the thermal stress caused by excessive temperature difference, while promoting the initial flow and infiltration of the resin to ensure that all areas of the blade are evenly heated; the purpose of the second heating is to accelerate the curing reaction of the resin through appropriate temperature and time, so that the material is further cured, control the stress distribution inside the blade, reduce the silver streak problem caused by uneven curing, and improve the mechanical properties and durability of the blade; the purpose of the third heating is to ensure that the blade material is completely cured, achieve the best mechanical properties and stability, and significantly improve the overall quality and service life of the blade.

[0065] This setting uses a gradient heating and curing strategy to ensure that the wind turbine blades are evenly and fully heated during the curing process, thereby improving the overall performance and quality of the blades. At the same time, it precisely controls the heating temperature and time to achieve the best curing effect and minimize energy consumption, reduce the occurrence of defects such as silver streaks, and improve the durability and service life of the blades.

[0066] Specifically, in step S3, the first heating temperature is set to 35-55°C, the curing time is set to 1-3.5h, the second heating temperature is set to 35-65°C, the second heating time is set to 0.5-2.5h, and the third heating is set to 60-85°C until curing.

[0067] Preferably, in step S3, the first heating temperature can be set at 40-50°C, the curing time can be set between 1.5-3h, the second heating temperature can be set at 50-60°C, the second heating time is 1-2h, and the third heating is heated at 65-80°C until the curing time is reached.

[0068] By adopting this relatively low curing temperature range, all areas of the product can reach the same temperature within a period of time. During the first heating, all areas can be guaranteed to heat up synchronously. At the same time, for areas with uneven structure or slow heating, and late exothermic peak, they can be kept warm before the second heating. At this time, all areas can reach the exothermic state or the peak of exothermic peak. At the same time, low-temperature curing can also reduce the peak of exothermic release of the product, making the exothermic release of the product less intense.

[0069] This setting ensures that the wind turbine blades are evenly and fully heated during the curing process, avoiding thermal stress caused by excessive heating temperature differences, thereby preventing the occurrence of silver streaks and improving the overall performance and quality of the blades.

[0070] Specifically, in step S3, the heating curve of the root preform and the shell root is: first, the root preform and the shell root are heated to 50°C within 30 minutes, then kept warm for 90 minutes, then heated to 60°C within 20 minutes, kept warm for 90 minutes, and finally heated to 65°C within 10 minutes, and kept warm for 180 minutes.

[0071] The temperature is heated to 50°C within 30 minutes and kept warm for 90 minutes. This stage is the preheating stage, which aims to gradually increase the material temperature, reduce the thermal stress caused by excessive temperature difference, and soften the resin at the same time, to ensure that the resin fully infiltrates the fiber-reinforced material and promote the initial curing reaction; the temperature is raised to 60°C within 20 minutes and kept warm for 90 minutes to accelerate the curing reaction rate of the resin, further eliminate the residual stress and uncured resin inside the material, and ensure the full progress of the curing reaction; the temperature is raised to 65°C within 10 minutes and kept warm for 180 minutes as the final heating stage, which aims to further promote the complete curing of the resin and achieve a stable performance state.

[0072] This setting can ensure that the wind turbine blade root prefabricated parts and the shell root are evenly and fully heated during the curing process, thereby improving the mechanical properties, durability and stability of the blade root, helping to reduce silver streak defects caused by uneven curing, and improving the overall quality and safety of the blade.

[0073] Specifically, in step S3, the heating curve of the trailing edge facade is: first, the trailing edge facade with a preheating temperature of 35°C is heated to 40°C within 10 minutes, and then kept warm for 90 minutes, then heated to 45°C within 10 minutes, kept warm for 60 minutes, then heated to 50°C within 10 minutes, kept warm for 60 minutes, and finally heated to 75°C within 50 minutes, and kept warm for 70 minutes.

[0074] By controlling the temperature increase rate at a moderate level during the initial heating and two heating processes, thermal stress and internal defects caused by rapid temperature increase are avoided; multiple insulation stages ensure that the resin can fully infiltrate the fiber reinforcement material and obtain a certain degree of solidification at each temperature stage; the final temperature is raised to 75°C and maintained to allow the resin to reach a fully solidified state at a higher temperature, thereby improving the mechanical properties and durability of the blade trailing edge facade.

[0075] This setting can effectively reduce thermal stress and improve the wettability of resin through refined temperature control, which helps to achieve uniform curing of resin and reduces defects and performance fluctuations caused by uneven curing. It not only ensures the curing quality, but also improves production efficiency and reduces production costs.

[0076] Specifically, in step S3, the UD preform heating curve is as follows: first, the UD preform with a preheating temperature of 35°C is heated to 40°C within 10 minutes, and then kept warm for 120 minutes, then heated to 45°C within 10 minutes, kept warm for 50 minutes, then heated to 50°C within 10 minutes, kept warm for 60 minutes, and finally heated to 75°C within 50 minutes, and kept warm for 50 minutes.

[0077] By slowly increasing the temperature during the initial preheating stage, the thermal stress of the UD preform caused by the large temperature difference can be reduced, and the resin can begin to soften, preparing for subsequent infiltration and curing; long-term insulation can ensure that the resin can fully infiltrate the fibers in the UD preform and improve the bonding strength between the layers; through multiple heating and insulation, the resin in the UD preform is gradually cured to form a stable microstructure, improving the mechanical properties and durability of the preform; finally, the temperature is raised to 75°C, so that the resin reaches a fully cured state, meeting the performance requirements of wind turbine blades for UD preforms.

[0078] This setting effectively reduces the thermal stress of the UD preform caused by temperature difference changes during the heating process by gradually increasing the temperature and keeping it warm for a long time, ensuring the structural integrity of the preform, improving the interlayer bonding strength and overall performance, and helping to achieve uniform curing of the resin, reducing defects and performance fluctuations caused by uneven curing, improving production efficiency, and reducing production costs.

[0079] Specifically, in step S5, the blade heating curing curve is as follows: first, the molded blade preheated at 40°C is kept warm for 60 minutes, then the temperature is raised to 50°C within 20 minutes and kept warm for 280 minutes.

[0080] The preheating temperature stage ensures the uniformity of the temperature inside the blade. Controlling the heating rate and holding time can effectively reduce the thermal stress caused by temperature changes, protect the integrity of the blade structure, promote full resin infiltration, enhance the bonding force between the fiber and the resin, and ultimately achieve complete curing of the blade.

[0081] Through the precise control of the heating and curing curve, the curing quality of the blades can be ensured, and the silver defects and performance fluctuations caused by uneven curing can be reduced, so that the blades have higher mechanical properties and durability and can better withstand the effects of wind and other external forces; a reasonable heating and curing curve can improve production efficiency and reduce production costs while ensuring quality, making the blade manufacturing process more controllable and facilitating the adjustment and optimization of process parameters.

[0082] Specifically, in step S3, the resin material for vacuum infusion is epoxy resin.

[0083] The material has excellent strength, rigidity and fatigue resistance, and is suitable for long-term stable operation of wind turbine blades in harsh environments.

[0084] Specifically, in step S6, the silver streaks are determined by drying.

[0085] like Figure 6-7 As shown in the figure, unlike the whitening due to dead wrapping, the silver streaks are mainly caused by deformation caused by stress. When the product is heated to a value higher than the TG value and the polymer reaches a high elastic state, the silver streaks disappear, and the whitening due to dead wrapping will become whiter when heated by the outside.

[0086] Example 1

[0087] According to the above description, by adjusting the abnormal cloth layer in the silver streak area, the problem of affecting the infusion resin content of the entire area, which in turn affects the uneven stress when the resin releases heat, is solved. It is necessary to adjust the uniformity of the infusion diversion, add continuous felt in the abnormal structural area, or cancel the abnormal cloth layer in the silver streak area, optimize the diversion in the silver streak area, ensure uniform resin content, and reduce the occurrence of silver streak problems.

[0088] like Figure 1 As shown, during the infusion and curing process, a separate heating system is set up for the area where silver streaks occur in the shell, which is divided into 1 blade root, 2 trailing edge vertical area, and 3 trailing edge UD preform area. The heating of the leading and trailing edge flanges in the corresponding areas is not included.

[0089] Set the heating curve to the corresponding partitions one by one. Figure 2The heating curve of the middle root prefabricated parts and the shell root is set to the 1 blade root heating zone, mainly to solve the root leading and trailing edges and circumferential silver streaks. Figure 3 The middle trailing edge elevation heating curve is set to the 2nd trailing edge elevation area to solve the silver streaks in the core material of the leeward elevation area of ​​the blade. Figure 4 The heating curve of the middle UD preform is set to the 3rd trailing edge UD preform area to solve the problem of silver streaks and whitening of the UD preform on the trailing edge of the blade.

[0090] During the blade mold closing and secondary heating process of bonding the web, Figure 5 The mold closing secondary heating temperature rise curve is set to 1 blade root, 2 trailing edge vertical area and 3 trailing edge UD preform area. By lowering the secondary heating temperature to 15-20℃ lower than the TG value of the FRP product, the silver streak and whitening problem is solved.

[0091] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for solving the problem of silver streaks and whitening during curing of wind turbine blades, characterized in that: The specific steps include: S1: Area division: according to the silver streak occurrence area, the silver streak whitening area in the blade forming mold is divided into separate areas and connected to an independent heating device; S2: Laying the fabric layer and the diversion structure; adjusting the fabric layer structure in the area where silver streaks occur, adjusting the uniformity of the perfusion diversion, and controlling the fat injection content in the area; S3: Half blade is heated and cured; gradient heating is used during vacuum infusion, and all areas are heated at a fixed temperature in steps after the curing process begins to ensure that all areas are heated synchronously; S4: mold closing; S5: Blade heating and curing; heating is performed by gradient heating, and the heating temperature is lower than the TG value of the product; S6: Inspection: whether there are silver streaks on the leaves according to the method of judging whether the silver streaks are white.

2. The method for solving the problem of silver streaks and whitening during curing of wind turbine blades according to claim 1, characterized in that: In step S1 , the silver streak occurrence area includes the blade root, the trailing edge UD, and the vertical surface area.

3. The method for solving the problem of silver streaks and whitening during curing of wind turbine blades according to claim 1, characterized in that: In step S2, the step of adjusting the uniformity of the infusion diversion includes: adding continuous felt in the small belly plate reinforcement area, and / or, canceling the cloth layer under the core rod, adjusting the core rod size, and / or, canceling the cloth layer at the end position of the UD rod or adding continuous felt under the pressing plate.

4. The method for solving the problem of silver streaks and whitening during curing of wind turbine blades according to claim 1, characterized in that: In step S3, the stepwise fixed temperature heating includes at least two heating steps.

5. The method for solving the problem of silver streaks and whitening during curing of wind turbine blades according to claim 4, characterized in that: In step S3, the step-fixed temperature heating includes a first heating, a second heating and a third heating.

6. The method for solving the problem of silver streaks and whitening during curing of wind turbine blades according to claim 5, characterized in that: In step S3, the first heating temperature is set to 35-55°C, the curing time is set to 1-3.5h, the second heating temperature is set to 35-65°C, the second heating time is set to 0.5-2.5h, and the third heating is set to 60-85°C until curing.

7. The method for solving the problem of silver streaks and whitening during curing of wind turbine blades according to claim 4, characterized in that: In step S3, the heating curve of the root preform and the shell root is as follows: first, the root preform and the shell root are heated to 50°C within 30 minutes, then kept warm for 90 minutes, then heated to 60°C within 20 minutes, kept warm for 90 minutes, and finally heated to 65°C within 10 minutes, kept warm for 180 minutes.

8. The method for solving the problem of silver streaks and whitening during curing of wind turbine blades according to claim 4, characterized in that: In step S3, the trailing edge facade heating curve is as follows: first, the trailing edge facade with a preheating temperature of 35°C is heated to 40°C within 10 minutes, and then kept warm for 90 minutes, then heated to 45°C within 10 minutes, kept warm for 60 minutes, then heated to 50°C within 10 minutes, kept warm for 60 minutes, and finally heated to 75°C within 50 minutes, and kept warm for 70 minutes.

9. The method for solving the problem of silver streaks and whitening during curing of wind turbine blades according to claim 4, characterized in that: In step S3, the UD preform heating curve is as follows: first, the UD preform with a preheating temperature of 35°C is heated to 40°C within 10 minutes, and then kept warm for 120 minutes, then heated to 45°C within 10 minutes, kept warm for 50 minutes, then heated to 50°C within 10 minutes, kept warm for 60 minutes, and finally heated to 75°C within 50 minutes, and kept warm for 50 minutes.

10. The method for solving the problem of silver streaks and whitening during curing of wind turbine blades according to claim 1, characterized in that: In step S5, the blade heating curing curve is as follows: first, the molded blade preheated at 40°C is kept warm for 60 minutes, then the temperature is raised to 50°C within 20 minutes and kept warm for 280 minutes.

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