Pre-formed body filled between pre-embedded thread sleeves for wind power blade root and preparation method of pre-formed body

Abstract

The invention belongs to the field of composite material forming processes, and particularly relates to a pre-embedded thread sleeve filling preform for a wind power blade root and a preparation method of the pre-embedded thread sleeve filling preform, and the pre-embedded thread sleeve filling preform is technically characterized in that the preform is obtained by assembling two or more than two monomer components together and integrally forming the two or more than two monomer components; the preformed body is made of 0-degree fiber, woven fabric or warp knitting fabric and epoxy resin; wherein the mass ratio of the 0-degree fibers is 10-99%, the mass of the epoxy resin is 1.0-5.0% of the mass of the 0-degree fibers, and the balance is the woven fabric or the warp knitting fabric; the epoxy resin is epoxy resin powder or epoxy resin suspension. According to the preformed body and the preparation method, the finished product quality of the root bolt sleeve is greatly improved, the load strength of the root bolt is effectively improved, and meanwhile the problems that a body is cracked and damaged due to uneven stress of a traditional root wedge-shaped piece and a metal bolt sleeve is pulled out due to insufficient interface strength are effectively solved.

Description

Technical Field

[0001] The invention belongs to the field of composite material forming technology, and in particular relates to a preformed body for filling between embedded screw sleeves at the root of a wind turbine blade and a preparation method thereof. Background Art

[0002] In the wind power industry, the blade root is mainly composed of bolt sleeves, plugs, sealing rings, core materials, pultruded composite wedges, triangles, and related fiber yarns and multi-axial fabrics, which are formed through a vacuum infusion process.

[0003] When the traditional vacuum infusion process is used to prepare the root, the surface of the pultruded composite is an inert surface, so the bonding interface performance with the metal screw sleeve surface is low. At the same time, it is difficult to ensure the consistency of the gaps and spacing between the components when they are placed. It is very easy to form defects such as cavities during infusion, which reduces the interfacial bonding strength between them and there is a risk of the metal bolt sleeve being pulled off the root. Summary of the invention

[0004] The purpose of the present invention is to provide a preformed body for filling the pre-embedded screw sleeves at the root of a wind turbine blade and a preparation method thereof. The above-mentioned problems can be effectively solved by adopting a wedge-shaped preformed body to replace the traditional composite material wedge-shaped body. The preformed body is a dry fiber or fabric structure with a desired shape, which can effectively eliminate the influence of the inert surface of the composite material on the interface between components, and greatly reduce the interface composition between the root components.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] The present invention provides a preformed body for filling the pre-embedded screw sleeves at the root of a wind turbine blade. The preformed body is formed by assembling two or more monomer components together to form an integral body.

[0007] The material of the preform includes 0° fiber, woven fabric or warp knitted fabric and epoxy resin;

[0008] The mass proportion of 0° fiber is 10-99%, the epoxy resin is 1.0-5.0% of the mass of 0° fiber, and the remainder is woven fabric or warp knitted fabric;

[0009] The epoxy resin is an epoxy resin powder or an epoxy resin suspension.

[0010] Furthermore, the epoxy resin powder is bisphenol A epoxy resin with a density of 1.2 to 1.3 g / cm 3 , the softening point is 60~100℃.

[0011] Furthermore, the epoxy resin powder has a particle size of 100 to 500 μm and a viscosity of 50 to 400 mPa.s at 100° C.

[0012] Furthermore, the epoxy resin suspension has a solid content of 3 to 8 wt %, a viscosity of 0.634 to 1.294 Pa.s at 23° C., and a particle size of 100 to 500 nm.

[0013] Furthermore, the epoxy resin suspension includes the following components: modified waterborne epoxy resin, surfactant and water.

[0014] Furthermore, the 0° fiber is any one or more of glass fiber, carbon fiber, ultra-high molecular weight polyethylene fiber or aramid fiber.

[0015] The present invention also provides a method for preparing a preformed body for filling between pre-embedded screw sleeves at the root of a wind turbine blade, comprising the following steps:

[0016] Spraying epoxy resin powder onto the surface of 0° fiber, woven fabric or warp knitted fabric or soaking 0° fiber, woven fabric or warp knitted fabric in epoxy resin suspension;

[0017] heating to melt the epoxy resin to obtain a pre-treated material;

[0018] Pultrusion is performed on the pre-treated material, and the pre-treated material is arranged on the raw material rack, and passes through the yarn feeding plate, cloth guide rod, stopper, heatable mold, traction machine, meter counter and cutting equipment in sequence;

[0019] Cut and bevel to obtain a preform.

[0020] The second method for preparing a preformed body filled between pre-embedded screw sleeves for wind turbine blade roots provided by the present invention comprises the following steps:

[0021] Spraying epoxy resin powder onto the surface of 0° fiber, woven fabric or warp knitted fabric or soaking 0° fiber, woven fabric or warp knitted fabric in epoxy resin suspension;

[0022] heating to melt the epoxy resin to obtain a pre-treated material;

[0023] The pretreated material is formed by a compression molding process. The treated fibers and fabrics are cut according to the requirements of the preform drawing and laid in the lower mold cavity according to the laying requirements. The upper mold and the lower mold are connected and transferred to the press platform. A pressure of 0.5 to 3 KN is applied to the mold and the temperature is raised to 60 to 170°C for 1 to 5 minutes. When the temperature drops below 60°C, the mold is opened to obtain the preform.

[0024] Furthermore, the spraying amount of epoxy resin powder is 10-40 g / m 2 .

[0025] Furthermore, the heating temperature is 60-150°C.

[0026] In summary, the present invention has the following beneficial effects:

[0027] The present invention adopts vacuum infusion to integrally form the bolt sleeve, core material and yarn / fabric, eliminates the use of pultruded wedges, effectively improves the bonding of the components in the bolt sleeve assembly, and also effectively improves the bearing capacity of the blade root bolt assembly. The static pull-out test of the bolt sleeve at the blade root shows that the pulling tension is increased from 1200KN to about 1800KN. DETAILED DESCRIPTION

[0028] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, a preformed body for filling the embedded screw sleeve at the root of a wind turbine blade and a preparation method thereof, as well as its specific implementation method, characteristics and effects are described in detail as follows.

[0029] The surface of the pultruded composite is inert, which means that it has a weak chemical or mechanical bonding ability with other materials, especially the interface bonding performance with the metal screw sleeve. This weak bonding interface may cause the bond between the screw sleeve and the composite to fail under high load or stress conditions, thus affecting the structural integrity of the blade root.

[0030] During the manufacturing process, it is difficult to achieve completely consistent gaps and spacing between components, which may result in underfilling or overfilling of certain areas when the resin is poured in. This non-uniformity can easily form cavities or unsaturated areas within the structure, becoming a potential source of defects.

[0031] The vacuum infusion process requires that the resin completely fills all the gaps between the mold and the fiber to ensure that there are no bubbles or cavities. However, due to the above-mentioned gap unevenness and other process instabilities, the resin may not be able to completely fill all the gaps, resulting in cavities inside. These cavities will weaken the overall strength and durability of the structure, especially in critical areas such as the blade root that are subject to large loads.

[0032] Due to the low interface bonding strength and the presence of infusion defects, the bonding between the metal bolt sleeve and the composite material may not be strong. When the blade is subjected to large external forces, especially repeated loads or impact loads, the bolt sleeve may come out of the composite material, causing structural failure at the root of the blade, posing a serious safety hazard.

[0033] In order to solve the above problems, the present specific embodiment provides a preformed body filled between the pre-embedded screw sleeves at the root of a wind turbine blade, wherein the preformed body is formed by assembling two or more monomer components together in one piece;

[0034] The material of the preform includes 0° fiber, woven fabric or warp knitted fabric and epoxy resin;

[0035] The mass proportion of 0° fiber is 10-99%, the epoxy resin is 1.0-5.0% of the mass of 0° fiber, and the remainder is woven fabric or warp knitted fabric;

[0036] The epoxy resin is an epoxy resin powder or an epoxy resin suspension.

[0037] It can be understood that the preform is assembled from two or more monomer components and manufactured through an integrated molding process, wherein the material of the preform is composed of 0° fiber, woven fabric or warp knitted fabric and epoxy resin.

[0038] 0° fiber usually refers to continuous fiber parallel to the main axis direction of the blade root, providing high strength and rigidity; woven fabrics or warp knitted fabrics (including but not limited to multi-axial warp knitted or woven fabrics such as uniaxial, biaxial, triaxial and quad-axial) provide additional mechanical strength and structural stability; epoxy resin is used to combine the fiber and fabric into a whole, playing the role of bonding and structural support.

[0039] Epoxy resin can be applied in the form of powder or suspension, each of which has its own advantages. Powders usually have better operability during processing, while suspensions can be more evenly coated on the fibers.

[0040] The preform technology provided in this specific embodiment is used for filling between the embedded screw sleeves at the root of the wind turbine blade, aiming to improve the structural strength and durability of the blade root and ensure the safety and stability of the blade during long-term use.

[0041] Exemplary epoxy resin powder is bisphenol A epoxy resin with a density of 1.2 to 1.3 g / cm 3 , the softening point is 60~100℃.

[0042] For example, the epoxy resin powder has a particle size of 100 to 500 μm and a viscosity of 50 to 400 mPa.s at 100° C.

[0043] It is understandable that the epoxy resin powder under the above-defined conditions can be evenly distributed and integrated into the fiber or other substrates, and it can effectively fill the gaps and reduce the risk of cavities or bubbles during the manufacturing process, thereby improving the structural integrity of the product.

[0044] Exemplarily, the epoxy resin suspension has a solid content of 3 to 8 wt %, a viscosity of 0.634 to 1.294 Pa.s at 23° C., and a particle size of 100 to 500 nm.

[0045] It can be understood that the moderate viscosity (0.634-1.294 Pa.s) at 23°C makes the suspension have good fluidity and is easy to evenly coat or impregnate the fiber substrate. This is particularly important for the manufacture of composite materials because it ensures that the epoxy resin evenly penetrates between the fibers, reduces the possibility of voids and uneven coatings, and thus improves the quality of the product.

[0046] At the same time, the suspension contains a higher epoxy resin solid content, which can provide higher mechanical strength and less volume shrinkage after curing. In the manufacturing process of composite materials, the use of this suspension can form a dense and strong cured layer, enhancing the structural properties of the final product.

[0047] The particle size of the epoxy resin particles in the suspension is between 100 and 500 nm. This nanoscale particle size provides a larger surface area for physical or chemical bonding with the substrate, thereby improving the interfacial bonding strength and the overall performance of the material.

[0048] Since the nanoparticles in the suspension can be evenly dispersed and penetrate into the fine structure of the substrate, this helps improve the interfacial bonding performance between epoxy resin and fiber materials or other substrates. Stronger interfacial bonding helps improve the durability and anti-stripping ability of the composite material, especially in high-stress areas such as the root of wind turbine blades.

[0049] In addition, because the suspension can evenly cover and penetrate between the fibers, the possibility of bubbles or cavities during the infusion or coating process is reduced. This helps to form a denser and more uniform material structure after curing, improving the mechanical properties and reliability of the material.

[0050] Exemplarily, the epoxy resin suspension includes the following components: modified waterborne epoxy resin, surfactant and water.

[0051] Exemplarily, the 0° fiber is any one or more of glass fiber, carbon fiber, ultra-high molecular weight polyethylene fiber or aramid fiber.

[0052] On the other hand, this specific embodiment also provides a method for preparing a preformed body filled between pre-embedded screw sleeves for the root of a wind turbine blade, comprising the following steps:

[0053] S1. Spray epoxy resin powder onto the surface of 0° fiber, woven fabric or warp knitted fabric or soak 0° fiber, woven fabric or warp knitted fabric in epoxy resin suspension.

[0054] It can be understood that, whether spraying the powder or infiltrating the suspension, it is ensured that the fiber or fabric surface is evenly covered with epoxy resin, which provides a good foundation for the subsequent melting and curing steps and ensures that the final preform structure is uniform.

[0055] At the same time, the epoxy resin forms a uniform film on the surface of the fiber or fabric, which can significantly improve the interfacial bonding strength between the fiber and the resin matrix, and ultimately improve the mechanical properties and durability of the preform.

[0056] S2. Heating to melt the epoxy resin to obtain a pre-treated material.

[0057] It can be understood that in this specific embodiment, the heating treatment causes the resin particles in the epoxy resin powder or suspension to melt and form a continuous resin film. After the epoxy resin is heated and melted, it can better penetrate between the fibers to form a dense resin layer, which not only improves the structural strength of the preform, but also reduces voids and defects.

[0058] At the same time, by controlling the heating temperature and time, the complete melting and uniform distribution of the epoxy resin can be ensured, thereby ensuring the process stability of the subsequent steps.

[0059] S3, pultruding the pretreated material, arranging the pretreated material on the raw material rack, and passing through the yarn feeding plate, the cloth guide rod, the limiter, the heatable mold, the traction machine, the meter counter and the cutting equipment in sequence.

[0060] It can be understood that the use of yarn feeding plates, cloth guide rods and limiters ensures that the fibers and fabrics maintain precise position and tension during processing, avoiding unevenness or misalignment in the preform; the heatable mold can not only ensure further curing of the epoxy resin, but also exert a certain pressure on the material in the mold, so that the density and structural performance of the preform are further optimized.

[0061] S4: Cut and bevel to obtain a preform.

[0062] Exemplarily, the pressure in the heatable mold is 0.5-3 KN, and the heating temperature is 60-170°C.

[0063] It is understandable that when the treated fiber or fabric passes through the heated mold, the surface resin melts again, and there is a certain pressure when the fiber and fabric pass through the mold cavity. Under the pressure again, the fibers and fabrics can be bonded together through the epoxy resin. After the heating is completed, as the temperature decreases, the surface resin condenses and hardens again, prompting the fiber and fabric to maintain the required cross-sectional shape. Finally, cut and bevel according to the shape requirements of the drawing to obtain the required preform consistent with the appearance of the traditional composite wedge.

[0064] Among them, the applied pressure helps to improve the interfacial bonding between the fiber and the resin. The pressure can compress the fiber and the resin, so that they form a tighter bond when heated. This tight bond manifests as higher mechanical strength and durability after curing. This is especially important for key parts such as the root of wind turbine blades that require high-strength bonding.

[0065] In addition, applying pressure during the heating process can effectively reduce the voids and bubbles inside the material and reduce the probability of defects. Uniform heating and appropriate pressure can avoid the formation of uneven solidification layers inside the material, ensure the quality stability and consistency of the preform, and thus improve the mechanical properties and service life of the finished product.

[0066] In a third aspect, this specific embodiment also provides a second method for preparing a preformed body for filling between pre-embedded screw sleeves at the root of a wind turbine blade, comprising the following steps:

[0067] P1. Spray epoxy resin powder onto the surface of 0° fiber, woven fabric or warp knitted fabric or soak 0° fiber, woven fabric or warp knitted fabric in epoxy resin suspension;

[0068] P2, heating to melt the epoxy resin to obtain a pre-treated material;

[0069] P3. The pretreated materials are molded by compression molding. The treated fibers and fabrics are cut according to the preform drawing requirements, and laid in the lower mold cavity according to the laying requirements. The upper mold and the lower mold are connected and transferred to the press platform. A pressure of 0.5 to 3 KN is applied to the mold and the temperature is raised to 60 to 170 ° C for 1 to 5 minutes. When the temperature drops below 60 ° C, the mold is opened to obtain the preform.

[0070] For example, in the above two preparation methods, the spraying amount of epoxy resin powder is 10-40 g / m 2 .

[0071] It is understandable that when the spraying amount is too large, the epoxy resin powder may form an overly thick resin layer in some areas. This will lead to uneven curing and resin enrichment. This enriched area may form a stress concentration point during curing, resulting in a decrease in the mechanical properties of the material and an increased risk of cracking or delamination. Too much epoxy resin will increase the weight of the final product, which is a significant disadvantage for structures that require lightweight, such as wind turbine blades. The increased weight will affect the dynamic performance of the blades and the efficiency of the wind turbine. Too much resin may flow during processing, causing mold contamination or adhesion of other equipment, and increasing cleaning and maintenance costs. In addition, excessive resin may also cause excessive volatiles to be generated during heating or curing, affecting the operating environment. Too little spraying will also result in insufficient resin coverage on the surface of the fiber or fabric, and a continuous resin film cannot be formed, resulting in insufficient infiltration, increasing the gaps between the fibers, and ultimately causing pores or cavities to appear inside the preform, weakening the structural strength and durability of the material.

[0072] If the amount of resin is insufficient, the interfacial bonding between the resin and the fiber will be weakened. This may cause the preform to be easily delaminated or peeled off when subjected to external forces, especially in key areas such as the root of wind turbine blades that are subject to high stress; due to insufficient bonding between the fiber and the resin, the overall mechanical properties of the preform (such as strength, stiffness and fatigue resistance) will be greatly reduced, affecting the service life and safety of the final product.

[0073] The spraying amount is closely related to the particle size of the epoxy resin powder. Too much or too little spraying amount may lead to adverse effects, such as uneven curing, insufficient interface bonding, and complicated processing. In this specific implementation method, the appropriate spraying amount and powder are selected according to the particle size of the epoxy resin powder to ensure the quality and performance of the preform.

[0074] Exemplarily, in the above two preparation methods, the heating temperature of the epoxy resin is 60-150°C.

[0075] Specifically, the heating methods include but are not limited to contact heating such as rollers and flat plates, non-contact heating such as infrared, ultrasonic and electromagnetic, and heating methods such as water bath, oil bath, electricity, and gas.

[0076] It is understandable that this temperature range can ensure that the resin is melted while also ensuring that the added epoxy resin does not affect the Tg value of the resin and the compatibility between the two during the subsequent integral infusion and curing.

[0077] Specifically, an appropriate melting temperature, such as a temperature range of 60 to 150°C, ensures that the resin in the epoxy resin powder or suspension can be completely melted during the heating process, thereby forming a continuous and uniform resin film. This uniform melting helps the resin to be evenly distributed on the surface of the fiber or fabric, enhances the interfacial bonding strength, and provides good substrate wettability in subsequent steps.

[0078] The Tg of a resin is an important indicator of its heat resistance and mechanical properties. In the heating range of 60 to 150°C, the resin can melt without excessive chemical reaction or premature curing. Maintaining the original Tg value of the resin is essential to ensure the high temperature performance and long-term stability of the preform.

[0079] In addition, the molecular structure and chemical properties of epoxy resin treated within this temperature range will not change significantly, which enables it to maintain good chemical and physical compatibility when subsequently combined with the integrally infused epoxy resin. This compatibility ensures that the final cured material has uniform properties without problems such as delamination or interface weakening.

[0080] In the following examples, the sources of raw materials used are as follows:

[0081] Epoxy resin: bisphenol A epoxy resin from Anhui Zhongbo New Materials Co., Ltd.

[0082] Glass fiber: ECT468G-2400tex from Chongqing International Composite Materials Co., Ltd.;

[0083] Biaxial warp knitted fabric: Changzhou Hongfa Zongheng New Materials Co., Ltd. 800g / m 2 ;

[0084] Modified epoxy resin: Glycidylamine resin produced by Huibo Technology New Materials (Shanghai) Co., Ltd.;

[0085] Surfactant: Huntsman Petrochemical X-AES linear fatty alcohol.

[0086] Embodiment 1: A preformed body for filling the pre-embedded screw sleeve at the root of a wind turbine blade and a preparation method thereof

[0087] The present embodiment provides a preformed body for filling the pre-embedded screw sleeve at the root of a wind turbine blade, which is obtained by assembling two monomer components together and forming them in one piece;

[0088] The materials of the preform, calculated by volume fraction, include 55% glass fiber, 44% biaxial warp knitted fabric and 1% epoxy resin;

[0089] The epoxy resin is epoxy resin powder, the specific material is bisphenol A epoxy resin, and the density is 1.2g / cm 3 , particle size range is 200μm; softening point: 80℃; viscosity at 100℃ is 200mPa.s.

[0090] The preparation method provided in this embodiment is a preparation method of pultrusion, which is specifically as follows:

[0091] S1. Spray epoxy resin powder on the surface of glass fiber and biaxial warp knitted fabric at a spraying amount of 20g / m 2 ;

[0092] S2, heating at 80° C. by infrared heating to melt the epoxy resin and obtain a pretreated material;

[0093] S3, arrange the pre-treated materials, place them on the raw material rack, and pass them through the threading plate, cloth guide rod, stopper, heatable mold (with required cross-sectional shape), traction machine, meter counter and cutting equipment in sequence, and the heating temperature of the heatable mold is 100°C;

[0094] S4. Cut and chamfer according to the shape requirements to obtain the required preformed body with the same shape as the traditional composite wedge-shaped part.

[0095] Embodiment 2: A preformed body for filling the pre-embedded screw sleeve at the root of a wind turbine blade and a preparation method thereof

[0096] The present embodiment provides a preformed body for filling the pre-embedded screw sleeve at the root of a wind turbine blade, which is obtained by assembling two monomer components together and forming them in one piece;

[0097] The materials of the preform, calculated by volume fraction, include 55% glass fiber, 44% biaxial warp knitted fabric and 1% epoxy resin;

[0098] The epoxy resin is an epoxy resin suspension, and the specific materials are modified water-based epoxy resin, surfactant and water; the solid content is 46wt.%, the viscosity is Pa.s (23°C): 0.894; and the particle size is 200nm.

[0099] The preparation method provided in this embodiment is a compression molding preparation method, which is specifically as follows:

[0100] P1, impregnating the glass fiber and biaxial warp knitted fabric into epoxy resin suspension;

[0101] P2. Using infrared heating, heating at 80°C to melt the epoxy resin and evaporate the water in the epoxy resin suspension to obtain a pretreated material;

[0102] P3. The pretreated materials are formed by a compression molding process. The treated glass fiber and biaxial warp knitted fabric are cut according to the requirements of the preform drawing, and laid in the lower mold cavity according to the laying requirements. The upper mold and the lower mold are connected and transferred to the press platform. A 2KN pressure is applied to the mold and the temperature is raised to 80℃ and maintained at a constant temperature and pressure for 3 minutes. When the temperature drops below 60℃, the mold is opened to obtain a preform with the same appearance as the traditional composite wedge.

[0103] Comparative Example 1

[0104] The present embodiment provides a preformed body for filling the pre-embedded screw sleeve at the root of a wind turbine blade, which is obtained by assembling two monomer components together and forming them in one piece;

[0105] The materials of the preform, calculated by volume fraction, include 55% glass fiber, 44% biaxial warp knitted fabric and 1% epoxy resin;

[0106] The epoxy resin is epoxy resin powder, the specific material is bisphenol A epoxy resin, and the density is 1.2g / cm 3 , particle size range is 200μm; softening point: 80℃; viscosity at 100℃ is 200mPa.s.

[0107] The preparation method provided in this embodiment is a preparation method of pultrusion, which is specifically as follows:

[0108] S1. Spray epoxy resin powder on the surface of glass fiber and biaxial warp knitted fabric at a spraying amount of 20g / m 2 ;

[0109] S2, heating at 50° C. by infrared heating to obtain a pretreated material;

[0110] S3, arrange the pre-treated materials, place them on the raw material rack, and pass them through the threading plate, cloth guide rod, stopper, heatable mold (with required cross-sectional shape), traction machine, meter counter and cutting equipment in sequence, and the heating temperature of the heatable mold is 100°C;

[0111] S4. Cut and chamfer according to the shape requirements to obtain the required preformed body with the same shape as the traditional composite wedge-shaped part.

[0112] Comparative Example 2

[0113] The present embodiment provides a preformed body for filling the pre-embedded screw sleeve at the root of a wind turbine blade, which is obtained by assembling two monomer components together and forming them in one piece;

[0114] The materials of the preform, calculated by volume fraction, include 55% glass fiber, 44% biaxial warp knitted fabric and 1% epoxy resin;

[0115] The epoxy resin is epoxy resin powder, the specific material is bisphenol A epoxy resin, and the density is 1.2g / cm 3 , particle size range is 200μm; softening point: 80℃; viscosity at 100℃ is 200mPa.s.

[0116] The preparation method provided in this embodiment is a preparation method of pultrusion, which is specifically as follows:

[0117] S1. Spray epoxy resin powder on the surface of glass fiber and biaxial warp knitted fabric at a spraying amount of 20g / m 2 ;

[0118] S2, heating the epoxy resin at 200° C. by infrared heating to obtain a pretreated material;

[0119] S3, arrange the pre-treated materials, place them on the raw material rack, and pass them through the threading plate, cloth guide rod, stopper, heatable mold (with required cross-sectional shape), traction machine, meter counter and cutting equipment in sequence, and the heating temperature of the heatable mold is 100°C;

[0120] S4. Cut and chamfer according to the shape requirements to obtain the required preformed body with the same shape as the traditional composite wedge-shaped part.

[0121] Performance Testing

[0122] The preforms obtained in Examples 1-2 and Comparative Examples 1-2 and other materials required for preparing wind turbine blade root bolt sleeve components such as metal bolt sleeves, wedge-shaped core materials, and fabrics are used to prepare blade body components using a vacuum infusion process.

[0123] Among them, the component structure is a wind turbine blade according to the structure: the upper and lower surfaces are symmetrically laid glass fiber fabrics, the middle layer is made of a book bolt sleeve, a preform, and a core material, wherein the metal bolt sleeve and the core material are placed front and back (the bolt sleeve is in front), and the preform is placed on the left and right sides, such as they are placed at intervals; the manufacturing size is length × width = 1700mm × 500mm.

[0124] Comparative Example 3

[0125] The UD wedge-shaped piece made of traditional glass fiber direct yarn is made of the same material and vacuum infusion process as in Example 1 to form a blade main body component with the same structural dimensions as in Example 1.

[0126] Comparative Example 4

[0127] The UD wedge-shaped piece made of bulked yarn is made into a blade main body component with the same structural dimensions as in Example 1 using the same material and vacuum infusion process as in Example 1.

[0128] For the blade main body components prepared in Examples 1 to 2 and Comparative Examples 1 to 4, root bolt sleeve components were prepared according to the blade root ply design, and a static pull-out test of the root bolt sleeve was performed according to DNVGL-ST-0376 (2015).

[0129] Sample preparation: First, the layers are laid according to the blade root structure design and preparation process, and then vacuum infused and cured with resin.

[0130] Sample size: length × width = 1700mm × 500mm.

[0131] Test method: The test was carried out in accordance with the test specification requirements of DNVGL-ST-0376 (2015). The test results are shown in Table 1.

[0132] Table 1. Performance test results

[0133] Static pull-out load of root part KN Failure mode description Example 1 1900 Fiber interlayer failure Example 2 1980 Fiber interlayer failure Comparative Example 1 1200 Failure of the interface between bolt sleeve and wedge Comparative Example 2 1300 Failure of the interface between bolt sleeve and wedge Comparative Example 3 1100 Failure of the interface between bolt sleeve and wedge Comparative Example 4 1250 Failure of the interface between bolt sleeve and wedge

[0134] According to the comparison of the above data, when the heating temperature of the epoxy resin is too low, the epoxy resin cannot be melted to a suitable viscosity and cannot penetrate into the fiber, resulting in poor molding of the preform and affecting the mechanical properties of the part. When the heating temperature of the epoxy resin is too high, after the epoxy resin is melted, the viscosity increases under the action of high temperature and it is also unable to penetrate into the fiber, resulting in poor molding of the preform and affecting the mechanical properties of the part.

[0135] In summary, compared with the traditional preparation process, the preparation method provided by the present invention greatly improves the quality of the finished product of the root bolt sleeve, effectively improves the load strength of the root bolt, and effectively solves the problem of body cracking damage caused by uneven force of the traditional root wedge and the problem of the metal bolt sleeve being pulled out due to insufficient interface strength. In addition, compared with the pultrusion process, the process control risk of the root bolt sleeve assembly is greatly reduced, the comprehensive cost of product production is further reduced, and it also provides effective guarantee for the improvement of subsequent production efficiency.

[0136] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been presented as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A preformed body filled between pre-buried screw sleeves at the root of a wind turbine blade, characterized in that: The preform is formed by assembling two or more monomer components together to form an integral body; The material of the preform includes 0° fiber, woven fabric or warp knitted fabric and epoxy resin; Among them, the mass proportion of 0° fiber is 10-99%, the epoxy resin is 1.0-5.0% of the mass of 0° fiber, and the remainder is woven fabric or warp knitted fabric; The epoxy resin is epoxy resin powder or epoxy resin suspension.

2. The preformed body filled between the pre-embedded screw sleeves for the root of a wind turbine blade according to claim 1, characterized in that: The epoxy resin powder is bisphenol A epoxy resin with a density of 1.2-1.3 g / cm 3 , the softening point is 60~100℃.

3. The preformed body filled between the pre-embedded screw sleeves for the root of a wind turbine blade according to claim 2, characterized in that: The epoxy resin powder has a particle size of 100-500 μm and a viscosity of 50-400 mPa.s at 100° C.

4. The preformed body filled between the pre-embedded screw sleeves for the root of a wind turbine blade according to claim 1, characterized in that: The epoxy resin suspension has a solid content of 3-8 wt %, a viscosity of 0.634-1.294 Pa.s at 23° C., and a particle size of 100-500 nm.

5. The method for preparing a preformed body filled between pre-embedded screw sleeves for the root of a wind turbine blade according to claim 1, characterized in that: The epoxy resin suspension comprises the following components: modified waterborne epoxy resin accounts for 2-7.7% by weight, surfactant accounts for 0.3-1% by weight, and water accounts for 92-97% by weight.

6. The preformed body filled between the pre-embedded screw sleeves for the root of a wind turbine blade according to claim 1, characterized in that: The 0° fiber is any one or more of glass fiber, carbon fiber, ultra-high molecular weight polyethylene fiber or aramid fiber.

7. The method for preparing a preformed body filled between pre-embedded screw sleeves for wind turbine blade roots according to any one of claims 1 to 6, characterized in that: The steps include: Spraying epoxy resin powder onto the surface of 0° fiber, woven fabric or warp knitted fabric or soaking 0° fiber, woven fabric or warp knitted fabric in epoxy resin suspension; heating to melt the epoxy resin to obtain a pre-treated material; Pultrusion is performed on the pre-treated material, and the pre-treated material is arranged on the raw material rack, and passes through the yarn feeding plate, cloth guide rod, stopper, heatable mold, traction machine, meter counter and cutting equipment in sequence; Cut and bevel to obtain a preform.

8. The method for preparing a preformed body filled between pre-embedded screw sleeves for wind turbine blade roots according to any one of claims 1 to 6, characterized in that: The steps include: Spraying epoxy resin powder onto the surface of 0° fiber, woven fabric or warp knitted fabric or soaking 0° fiber, woven fabric or warp knitted fabric in epoxy resin suspension; heating to melt the epoxy resin to obtain a pre-treated material; The pretreated material is formed by a compression molding process. The treated fibers and fabrics are cut according to the requirements of the preform drawing and laid in the lower mold cavity according to the laying requirements. The upper mold and the lower mold are connected and transferred to the press platform. A pressure of 0.5~3KN is applied to the mold and the temperature is raised to 60~170℃ for 1~5min. When the temperature drops below 60℃, the mold is opened to obtain the preform.

9. The method for preparing a preformed body filled between pre-embedded screw sleeves for wind turbine blade roots according to claim 7 or 8, characterized in that: The spraying amount of the epoxy resin powder is 10-40 g / m 2 .

10. The method for preparing a preformed body filled between pre-embedded screw sleeves for wind turbine blade roots according to claim 7 or 8, characterized in that: The heating temperature is 60-150°C.