A sandwich structure digital model forming method based on a measured cross-sectional profile

Abstract

This invention provides a method for forming a digital model of a sandwich structure based on measured cross-sectional contours. The method includes: pouring a shell without the sandwich structure; marking the sandwich structure areas on the PS and SS surfaces respectively; laying isolation material; setting a U-shaped sealing strip; and pre-filling the rear corner of the PS surface with structural adhesive; applying adhesive, placing the core material, and applying adhesive again to the thicker areas of the SS and PS surfaces; applying structural adhesive to the U-shaped sealing strip area; closing the SS and PS surfaces and heating and curing the mold to obtain a molding template, and marking the sandwich areas; cutting several template blocks according to the markings to obtain their cross-sectional views, placing them back in their original positions, recording the positions, obtaining image data, importing it into a three-dimensional simulation system, reconstructing the cross-sectional views, and laying out the entire length to obtain a digital model of the sandwich core material. This invention ensures a high degree of matching between the core material and the shell, improving the reliability and consistency of blade manufacturing.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, and in particular to a method for forming a digital model of a sandwich structure based on measured cross-sectional profiles. Background Technology

[0002] As wind turbine blades continue to develop towards larger and lighter designs, the sandwich structure is increasingly widely used in blade shells. The sandwich structure typically consists of an outer skin, a lightweight foam core (such as PET foam), and an inner skin. The precision of the fit between the core material and the shell skin, the density of the filling at the corners of the core material, and the uniformity of the adhesive layer thickness on the upper and lower surfaces of the core material determine the blade's local buckling resistance and fatigue life.

[0003] Existing sandwich structures mostly employ a one-step injection molding method, where the sandwich core material is laid in during the shell layup stage, followed by resin injection and curing integrally with the shell skin. However, this method faces the following problems during the initial blade prototype production or new blade design development stages: First, the shell of the new leaf shape will undergo unpredictable springback deformation after demolding. There is a significant deviation between the core material profile designed in the design stage and the actual internal profile of the shell after curing. This results in insufficient fit of the core material processed according to the drawings during trial laying, and local gaps or stress concentration are easily generated after mold closing.

[0004] Secondly, due to the lack of data support for the actual internal shape of the shell, the trial production stage usually adopts the method of repeatedly grinding the core material or adding glue by trial and error, which is time-consuming, costly, and difficult to guarantee consistency and reliability.

[0005] Third, even with a step-by-step process of first fabricating the shell and then bonding the core material, there is a lack of a low-cost and repeatable method to obtain the complete surface profile of the shell's temporal region. Traditional 3D scanning equipment is expensive and difficult to effectively measure narrow and complex curved areas inside the blades.

[0006] Fourth, the quality of the first blade prototype directly determines the process window for subsequent mold correction and mass production. If the sandwich area is not properly matched, it will lead to defects such as uncontrolled adhesive layer thickness (local lack of adhesive or excessive adhesive cracking), core material slippage, and corner cavities. In severe cases, the shell needs to be scrapped, which will greatly affect the trial production progress and cost.

[0007] Therefore, there is an urgent need for a method that can accurately acquire the internal surface data of the sandwich area of ​​the shell for the first blade prototype stage, and reverse design the core material based on the measured data. Summary of the Invention

[0008] This invention aims to provide a sandwich structure forming method that enables rapid adaptation between the sandwich structure model and the shell model, in order to solve problems such as mismatch between the existing core material profile and the actual shell profile, and uncontrollable adhesive layer thickness. This invention realizes the reverse reconstruction from the physical object to the digital twin model, ensuring a high degree of matching between the core material and the shell, and improving the reliability and consistency of blade manufacturing.

[0009] To achieve the above objectives, the basic solution of the present invention is as follows: A method for forming a digital model of a sandwich structure based on a measured cross-sectional profile, comprising: pouring a shell without a sandwich structure; grinding the blade root mold joint of the formed shell; and performing a trial mold-closing operation to ensure that the mold-closing gap meets the process requirements; marking the sandwich structure area on the PS and SS surfaces of the shell according to the design drawings, and laying isolation material according to the marked areas to form an isolation layer; setting a U-shaped baffle strip on the SS surface isolation layer, the opening of the baffle strip facing the mold joint direction, and pre-filling the corner of the PS surface with structural adhesive; determining the area in the sandwich structure that exceeds a preset thickness threshold, applying structural adhesive to the corresponding area on the SS and PS surfaces, placing the core material, and applying structural adhesive to the upper surface of the core material; and within the area enclosed by the U-shaped baffle strip... Structural adhesive is applied; the PS and SS surfaces are joined together and molded, and after appropriate adhesive extrusion, the mold is heated and cured; after curing, the mold is opened to obtain the molding template, and the sandwich area is marked with whole-meter and chordal positions on the molding template; the molding template is cut along the marked positions using a cutting tool to obtain several template blocks, and cross-sectional views of the template blocks are obtained; the template blocks are placed back to their original positions corresponding to the PS surface shell, and the height of the template blocks is fixed according to the set horizontal baseline to ensure that their measurement posture is consistent with the molding state; the whole-meter positions of the positioned molding template blocks are recorded to obtain image data, which is imported into a three-dimensional simulation system to reconstruct the cross-sectional view of the sandwich area; the cross-sectional view is used to lay out the sandwich core material along the blade axis by whole meters according to the cross-sectional view.

[0010] Furthermore, the mold closing gap meets the process requirement of 2-10mm.

[0011] Furthermore, the isolation layer completely covers the sandwich structure area, and its edges extend outward by 200-400mm.

[0012] Furthermore, the preset thickness threshold is 300mm.

[0013] Furthermore, when the structural adhesive is evenly extruded from the mold seam and the sealant strip, and the adhesive layer thickness is moderate and the pressure distribution is uniform, the extrusion is considered appropriate.

[0014] Furthermore, when cutting the molding template, the width of each cutting point is 50-100mm.

[0015] Furthermore, it also includes: generating processing drawings based on the digital model, performing nesting processing on the core material raw materials based on the processing drawings to obtain customized core materials; and performing layup verification and mold closing verification on the customized core materials.

[0016] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: A shell without a sandwich structure is poured in; the blade root mold joint is ground; a trial mold-closing operation is performed to ensure the mold gap meets process requirements; the sandwich structure area is marked on the PS and SS surfaces according to the design drawings, and isolation material is laid according to the marked areas to form an isolation layer; a U-shaped adhesive strip is set on the SS surface isolation layer, with its opening facing the mold joint direction; structural adhesive is pre-filled at the rear corner of the PS surface; areas in the sandwich structure exceeding a preset thickness threshold are identified, and structural adhesive is applied to the corresponding areas on the SS and PS surfaces; the core material is placed, and structural adhesive is applied to the upper surface of the core material to effectively control the adhesive layer thickness; simultaneously, structural adhesive is applied within the area enclosed by the U-shaped adhesive strip; the PS and SS surfaces are closed for molding; and after appropriate adhesive extrusion, the process continues... The mold is heated and cured. After curing, the mold is opened to obtain a forming template. The sandwich area is marked with full-meter and chordal positions on the forming template. The forming template is cut along the marked positions using a cutting tool to obtain several template blocks, and the cross-sectional view of the template blocks is obtained. The template blocks are placed back into the original positions corresponding to the PS surface shell. The height of the template blocks is fixed according to the set horizontal baseline to make its measurement posture consistent with the forming state. The full-meter positions of the positioned forming template blocks are recorded to obtain image data, which is imported into the three-dimensional simulation system to reconstruct the cross-sectional view of the sandwich area. Based on the cross-sectional view, the full-meter layout is carried out along the blade axis to draw a digital model of the sandwich core material. The digital model is completely based on the measured profile data to ensure the height matching between the core material and the shell, thereby improving the usability of manufacturing in the blade. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating a method for forming a digital model of a sandwich structure based on a measured cross-sectional profile, as described in one embodiment. Detailed Implementation

[0018] To make the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] like Figure 1 As shown, a method for forming a digital model of a sandwich structure based on measured cross-sectional profiles is provided, including the following steps: Step S1: Pour in a shell without a sandwich structure, grind the blade root mold joint of the molded shell, and perform a trial mold closing operation to ensure that the mold closing gap meets the process requirements.

[0020] The mold closing gap meets the process requirement of 2-10mm.

[0021] Specifically, during the layup process of the blade shell (PS surface and SS surface), sandwich materials (such as PET foam) are not laid. Instead, the outer skin, main beam, core material (referring to structural core material, not sandwich structure), and inner skin are laid out in a conventional manner. Then, resin is injected and cured to obtain a base shell without sandwiches. The inner surface profile represents the actual shell outline after curing.

[0022] The leaf root mold joint is ground according to the process requirements, and then a trial mold closing operation is carried out. The interference points are eliminated by local grinding or adding shims. The feeler gauge or gap gauge is used to confirm that the mold joint gap meets the process requirements (2-10mm). The purpose of the trial mold closing is to ensure that the mold can close evenly in the subsequent pressing process and avoid local over-pressure or under-pressure.

[0023] Step S2: Mark the sandwich structure area on the PS and SS surfaces of the shell according to the design drawings, and lay the isolation material according to the marked area to form an isolation layer.

[0024] The isolation layer completely covers the sandwich structure area, and the edges extend outward by 200-400mm.

[0025] Specifically, on the PS and SS surfaces of the shell, the areas where the sandwich structure needs to be made are marked according to the design drawings. The axial position can be marked at whole-meter intervals (e.g., every 1 meter). At the same time, the chord start and end positions are marked. The marked area can serve as the positioning reference for all subsequent operations.

[0026] Apply isolation material (such as a perforated isolation film or release cloth) to the corresponding positions of the sandwich on the PS and SS surfaces. The isolation range should completely cover the sandwich area and extend outward by 200-400mm. The isolation layer prevents the structural adhesive to be filled later from permanently bonding with the shell body, making it easy to remove the molded template completely from the shell after molding.

[0027] Step S3: Set a door-shaped adhesive strip on the SS surface isolation layer, with the opening of the adhesive strip facing the mold seam direction, and pre-fill the corner of the PS surface with structural adhesive.

[0028] Specifically, a U-shaped adhesive strip is installed on the SS surface release film, with the opening of the adhesive strip facing the mold seam. The adhesive strip is used to limit the flow range of structural adhesive during molding and prevent structural adhesive from overflowing into non-bonding areas. At the same time, structural adhesive is pre-filled at the rear corner of the PS surface (this area has complex geometry and is prone to cavities) to ensure that the corner area is completely filled after the mold is closed.

[0029] Step S4: Identify the areas in the sandwich structure that exceed the preset thickness threshold, apply structural adhesive to the corresponding areas on the SS and PS surfaces, place the core material, and apply structural adhesive to the surface of the core material.

[0030] The preset thickness threshold is 300mm.

[0031] Specifically, in the sandwich structure, areas exceeding a preset thickness threshold (30mm) are identified. A sandwich layering method of structural adhesive, core material, and structural adhesive is employed, including: first, applying a layer of structural adhesive to the corresponding position on the SS surface, then placing the core material (such as PET foam), and then applying another layer of structural adhesive to the upper surface of the core material; simultaneously, placing the core material at the corresponding position on the PS surface and applying adhesive to both sides. Placing the core material on both the PS and SS surfaces simultaneously ensures a tight bond between the upper and lower core materials through the adhesive layers after mold closing, preventing adhesive cracking caused by concentrated heat release during curing due to excessively thick adhesive layers on one side.

[0032] Step S5: Apply structural adhesive to the area enclosed by the U-shaped adhesive strip.

[0033] Specifically, structural adhesive is uniformly applied to the area enclosed by the U-shaped adhesive strip to form a continuous sandwich structure together with the core material layer and pre-filled adhesive after molding.

[0034] Step S6: Join the PS surface and SS surface together for molding, and heat and cure the mold after the appropriate amount of glue is extruded.

[0035] Among them, when the structural adhesive is evenly extruded from the mold seam and the adhesive strip, the adhesive layer thickness is moderate and the pressure distribution is uniform, the extrusion is considered appropriate.

[0036] Specifically, the PS and SS surface molds are closed and pressed together. During the pressing process, the extrusion of the structural adhesive is checked by observing the inner cavity of the shell to ensure that the adhesive is evenly extruded from the mold seam and the adhesive strip, indicating that the adhesive layer thickness is appropriate and the pressure distribution is uniform. After confirming that the extrusion is appropriate, the mold heating system is turned on, and the adhesive is heated and cured according to the curing curve of the structural adhesive.

[0037] Step S7: After curing, open the mold to obtain the molding template, and mark the whole meter position and chord position of the sandwich area on the molding template.

[0038] Specifically, after curing, the mold is opened. At this point, a molding template that perfectly fits the internal surface of the shell has been formed in the sandwich area of ​​the shell. The molding template is composed of cured structural adhesive and core material. On this molding template, the axial whole-meter position and chord position are precisely marked according to the marking in step S2.

[0039] Step S8: Use a cutting tool to cut the forming template along the marked position to obtain several template blocks, and obtain a cross-sectional view of the template blocks.

[0040] When cutting the molding template, the width of each cutting point is 50-100mm.

[0041] Specifically, a cutting tool (such as an angle grinder or circular saw) is used to cut along the marked whole-meter position, with the cutting direction perpendicular to the blade axis. The width of each cut point is usually 50-100mm. The cut molding template block is then removed. The cross-section of each template block accurately reflects the contour curve of the internal surface of the shell at that whole-meter position. The cross-section of the template block is photographed or scanned to obtain a whole-meter cross-sectional diagram.

[0042] Step S9: Place several template blocks back into their original positions corresponding to the PS surface shell, and fix the height of the template blocks according to the set horizontal baseline so that their measurement posture is consistent with the forming state.

[0043] Specifically, the cut template block is placed back into its original position on the PS surface shell, and the height of the template block is fixed according to the pre-set horizontal baseline to ensure that the posture is consistent with the forming state during subsequent measurements, thereby achieving the calibration of the forming template on the PS surface.

[0044] Step S10: Record the whole-meter position of the positioned molding template block to obtain image data, import it into the three-dimensional simulation system, and reconstruct the cross-sectional view of the sandwich area.

[0045] Specifically, high-definition photos of the positioned forming template block are taken at the whole meter position to obtain image data. The image data should include a ruler or a reference object with known dimensions for subsequent dimension calibration.

[0046] The obtained image data is imported into a 3D simulation system (such as photogrammetry-based 3D reconstruction software). The system reconstructs the 3D contour of the forming template at each whole-meter position through pixel calibration, feature point matching, and surface fitting, and generates a comparison deviation map between the theoretical and measured surface curves at that position. Finally, it draws an accurate cross-sectional view of the sandwich area at each meter position, obtaining reliable process parameters and core material drawings. Moreover, the method of obtaining the cross-sectional view is simple and reliable.

[0047] Step S11: Based on the cross-sectional diagram, lay out the entire length along the blade axis to obtain the digital model of the sandwich core material.

[0048] Specifically, based on the obtained full-meter cross-sectional diagram of the template block, the template block is laid out along the blade axis and assembled to obtain a digital model of the sandwich core material, thus realizing the digital model forming of the sandwich structure. This digital model is entirely based on the measured surface data, ensuring the height matching between the core material and the shell, reducing quality problems such as excessive mold gap and local extrusion, and improving the reliability and consistency of blade manufacturing.

[0049] By constructing a three-dimensional digital model of the sandwich structure through cross-sectional contour, the design difficulties such as poor matching of the sandwich structure, uncontrollable adhesive layer, and unstable blade structure are fundamentally solved, design risks are avoided, and the production efficiency of wind turbine blades is improved.

[0050] After step S11, the process further includes: generating processing drawings based on the digital model, performing nesting processing on the core material raw materials based on the processing drawings to obtain customized core materials; and performing layup verification and mold closing verification on the customized core materials.

[0051] Specifically, based on the obtained digital model, a sandwich core material processing drawing is generated. The drawing accurately reflects the required chord width, thickness, and edge chamfer shape of the core material at each axial position. The core material raw material is then cut according to the processing drawing to obtain a customized core material that closely matches the actual surface of the shell.

[0052] The obtained customized new material is subjected to layup verification and mold closing verification to ensure that the resulting sandwich structure meets the process requirements.

[0053] Among them, the layup verification involves trial laying of customized core material in the unfilled shell layup to check the core material’s surface fit, angle matching, corner filling and overall filling quality, ensuring that there is no warping, voids or interference.

[0054] Mold fitting verification involves trial mold fitting after the core material is laid out, and tracking and measuring whether the gap between the mold fitting seams meets the process requirements in order to verify the fitting accuracy between the core material and the shell.

[0055] In this embodiment, a shell without a sandwich structure is poured in, its blade root mold joint is sanded, and a trial mold-closing operation is performed to ensure the mold gap meets the process requirements. According to the design drawings, sandwich structure areas are marked on the PS and SS surfaces respectively, and isolation material is laid according to the marked areas to form an isolation layer. A U-shaped adhesive strip is set on the SS surface isolation layer, with its opening facing the mold joint direction. Structural adhesive is pre-filled at the rear corner of the PS surface. Areas in the sandwich structure exceeding a preset thickness threshold are identified, and structural adhesive is applied to corresponding areas on the SS and PS surfaces. The core material is placed, and structural adhesive is applied to the upper surface of the core material to effectively control the adhesive layer thickness. Simultaneously, structural adhesive is applied within the area enclosed by the U-shaped adhesive strip. The PS and SS surfaces are closed for molding, and after appropriate adhesive extrusion, the mold is heated and cured. After curing, the mold is opened to obtain the forming template. The sandwich area is marked with full-meter and chordal positions on the forming template. The forming template is cut along the marked positions using a cutting tool to obtain several template blocks, and the cross-sectional view of the template blocks is obtained. The template blocks are placed back into the original position corresponding to the PS surface shell. The height of the template blocks is fixed according to the set horizontal baseline to make its measurement posture consistent with the forming state. The full-meter position of the positioned forming template blocks is recorded to obtain image data, which is imported into the three-dimensional simulation system to reconstruct the cross-sectional view of the sandwich area. Based on the cross-sectional view, the full-meter layout is carried out along the blade axis to draw the digital model of the sandwich core material. The digital model is completely based on the measured profile data to ensure the height matching between the core material and the shell, thereby improving the usability of manufacturing in the blade.

[0056] In summary, the present invention has the following advantages over the prior art: First, by using a process sequence of first making the shell and then pressing it, the risk of core material drifting during the injection process is avoided. Moreover, the pressing template directly replicates the actual internal shape of the shell after curing, providing an accurate data basis for core material design.

[0057] Secondly, a symmetrical sandwich layering method of structural adhesive, core material, and structural adhesive is adopted to effectively control the adhesive layer thickness and prevent adhesive cracking caused by excessive thickness on one side.

[0058] Third, this invention achieves reverse reconstruction from physical objects to digital twin models, and the obtained cross-sectional diagrams have high accuracy and good repeatability.

[0059] Fourth, the digital model of the sandwich structure is based entirely on measured surface data, which ensures a high degree of matching between the core material and the shell, reduces quality problems such as excessive mold clearance and local extrusion, and improves the reliability and consistency of blade manufacturing.

[0060] Fifth, a closed-loop feedback loop is formed through product verification steps to ensure the usability of the core material in actual production.

[0061] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0062] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for forming a digital model of a sandwich structure based on measured cross-sectional profile, characterized in that, include: The shell without a sandwich structure is poured in, the blade root mold joint of the molded shell is ground, and a trial mold closing operation is performed to ensure that the mold closing gap meets the process requirements. According to the design drawings, the sandwich structure areas are marked on the PS and SS surfaces of the shell respectively, and the isolation material is laid on the marked areas to form an isolation layer; A U-shaped adhesive strip is set on the SS surface isolation layer, with the opening of the adhesive strip facing the mold seam direction, and structural adhesive is pre-filled at the rear corner of the PS surface; Identify the areas in the sandwich structure that exceed the preset thickness threshold, apply structural adhesive to the corresponding areas on the SS and PS surfaces, place the core material, and apply structural adhesive to the upper surface of the core material. Structural adhesive is applied to the area enclosed by the U-shaped adhesive strip; The PS and SS surfaces are joined together and molded, and after the appropriate amount of glue is extruded, the mold is heated and cured. After curing, the mold is opened to obtain the molding template. The sandwich area is marked with whole-meter positions and chord positions on the molding template. The forming template is cut along the marked positions using a cutting tool to obtain several template blocks, and cross-sectional views of the template blocks are obtained. Place the template blocks back into their original positions corresponding to the PS surface shell, and fix the height of the template blocks according to the set horizontal baseline to make their measurement posture consistent with the forming state. The position of the pre-positioned molding template block is recorded in whole meters to obtain image data, which is then imported into a three-dimensional simulation system to reconstruct a cross-sectional view of the sandwich area. Based on the cross-sectional diagram, a full-meter layout is performed along the blade axis to obtain a digital model of the sandwich core material.

2. The method for forming a digital model of a sandwich structure based on measured cross-sectional profile according to claim 1, characterized in that, The mold closing gap meets the process requirement of 2-10mm.

3. The method for forming a digital model of a sandwich structure based on a measured cross-sectional profile according to claim 1, characterized in that, The isolation layer completely covers the sandwich structure area, and its edges extend outward by 200-400mm.

4. The method for forming a digital model of a sandwich structure based on a measured cross-sectional profile according to claim 1, characterized in that, The preset thickness threshold is 300mm.

5. The method for forming a digital model of a sandwich structure based on a measured cross-sectional profile according to claim 1, characterized in that, When the structural adhesive is evenly extruded from the mold seam and the sealant strip, and the adhesive layer thickness is moderate and the pressure distribution is uniform, the extrusion is considered appropriate.

6. The method for forming a digital model of a sandwich structure based on a measured cross-sectional profile according to claim 1, characterized in that, When cutting the molding template, the width of each cutting point is 50-100mm.

7. The method for forming a digital model of a sandwich structure based on a measured cross-sectional profile according to claim 1, characterized in that, Also includes: Based on the digital model, processing drawings are generated, and the core material raw materials are cut and processed according to the processing drawings to obtain customized core materials; The customized core material was subjected to layup verification and mold closing verification.

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