Special-shaped structural part knitting process reasoning method and system based on eccentricity theory

Abstract

The invention relates to the technical field of three-dimensional weaving processes, in particular to a special-shaped structural part weaving process reasoning method and system based on an eccentricity theory. The method comprises the following steps of: obtaining a homogenized surface grid of a core mold key section by utilizing the three-dimensional model; obtaining a knitting angle vector field based on an eccentric knitting theory and the homogenized surface grid; according to the knitting angle vector field, expected fabric structures on different areas of a core mold are optimized; and through the expected fabric structure, reasoning and generating eccentric knitting process parameters. According to the process parameters generated through reasoning, fabric defects at complex geometrical characteristics of the special-shaped structural part are completely eliminated, the coverage rate difference of the inner side and the outer side is reduced by 24% or above, the knitting pose constraint of a traditional knitting process is broken through, and a theoretical basis is provided for low-cost, rapid and automatic knitting production line process planning software of the large-size special-shaped structural part.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional weaving technology, and in particular to a weaving technology reasoning method and system for special-shaped structural parts based on eccentricity theory. Background Art

[0002] At present, with the increasing demand for lightweight large-sized special-shaped structural parts in the aerospace field, there is an increasing demand for low-cost and rapid manufacturing of large aircraft bulkheads, floor beams, rocket tail nozzles, throat liners and other structural parts using composite materials instead of traditional metal materials. At the same time, it is difficult to form special-shaped structural parts efficiently and accurately using processes such as manual placement, automatic placement, and automatic winding. Therefore, the three-dimensional weaving precision forming technology for special-shaped structural parts has become a current research hotspot.

[0003] In the prior art, analytical methods are usually used to infer the weaving process parameters of special-shaped structural parts with geometric features such as large curvature and variable cross-section. This method has the following shortcomings: First, it is difficult to establish a mapping relationship between process parameters and fabric structure by given geometric constraints, so as to infer the weaving process parameters in eccentric weaving; second, weaving using the inferred process parameters will result in fabric defects such as fabric stacking and sparseness. The prior art uses a kinematic method to infer the process parameters of special-shaped structural parts under the eccentric weaving process, but this method takes the weaving angle as a single target and is difficult to solve the fabric defect problem in special-shaped structural parts.

[0004] Therefore, in order to achieve precise forming of special-shaped structural parts, it is urgent to propose a high-quality weaving process parameter reasoning method that can eliminate fabric defects. Summary of the invention

[0005] In view of the defects in the prior art, the present invention provides a method and system for reasoning the weaving process of special-shaped structural parts based on eccentricity theory.

[0006] On the one hand, the present invention provides a method for reasoning the weaving process of a special-shaped structural part based on the eccentric theory, comprising the following steps: obtaining a three-dimensional model of a core mold of a special-shaped structural part; using the three-dimensional model, obtaining a uniform surface grid of a key section of the core mold; obtaining a weaving angle vector field based on the eccentric weaving theory and the uniform surface grid; optimizing the desired fabric structure on different regions of the core mold according to the weaving angle vector field; and generating eccentric weaving process parameters by reasoning through the desired fabric structure. The present invention uses the three-dimensional model of the core mold of the special-shaped structural part to obtain the uniform surface grid of the key section, thereby ensuring the accuracy of the basic data of the weaving process design and providing a reliable basis for subsequent process reasoning; based on the eccentric weaving theory and the uniform surface grid, the weaving angle vector field is calculated, effectively combining the theoretical model with the actual weaving requirements, and improving the scientificity and accuracy of the weaving process; through the weaving angle vector field, the desired fabric structure on different regions of the core mold is optimized, and the eccentric weaving process parameters are generated by reasoning, thereby realizing the precise reasoning of the weaving process of the special-shaped structural part, which is conducive to eliminating the fabric defect problem existing in the weaving process.

[0007] Optionally, the method of using the three-dimensional model to obtain a homogenized surface mesh of the key cross section of the core mold includes: using the three-dimensional model to extract point cloud data; orthogonally projecting the point cloud data to obtain the center line of the heterogeneous structural part; reconstructing the key cross section of the core mold using the spatial relationship between the center line and the point cloud data; and connecting the points of the key cross section through a custom call sequence to generate a homogenized surface mesh. The present invention provides a rich data source for subsequent mesh generation by extracting the point cloud data of the three-dimensional model of the core mold, thereby ensuring the comprehensiveness and accuracy of the data; orthogonally projecting the point cloud data to obtain the center line of the heterogeneous structural part not only simplifies the data structure, but also provides a benchmark for the reconstruction of the key cross section, making subsequent operations more accurate and efficient; reconstructing the key cross section of the core mold using the spatial relationship between the center line and the point cloud data, and connecting the points of the key cross section through a custom call sequence to generate a homogenized surface mesh, which not only ensures the uniformity and continuity of the mesh, but also provides high-quality input data for subsequent weaving process reasoning, thereby improving the accuracy and reliability of the entire weaving process.

[0008] Optionally, the method of obtaining the braiding angle vector field based on the eccentric braiding theory and the homogenized surface grid includes: establishing a spatial relationship equation according to the position of the yarn on the guide ring and the landing point position on the core mold under the eccentric braiding process; performing time differential operation on the spatial relationship equation to obtain a braiding speed expression of the spindle speed mapped on the core mold surface; obtaining a yarn landing point position expression according to the braiding speed expression; obtaining a braiding angle vector field based on the yarn landing point position expression and the homogenized surface grid. The present invention establishes an accurate mathematical model based on the spatial relationship between the yarn landing points on the guide ring and the core mold under the eccentric braiding process, providing a solid theoretical basis for the calculation of the braiding speed; by performing time differential operation on the spatial relationship equation, the mapping relationship of the spindle speed on the core mold surface, that is, the braiding speed expression, is obtained, realizing the transformation from theory to practice, and providing a basis for the calculation of the braiding angle; combining the yarn landing point expression and the homogenized surface grid, the braiding angle vector field is successfully generated, which improves the accuracy of the braiding process and promotes the wide application of eccentric braiding technology in the manufacture of special-shaped structural parts.

[0009] Optionally, the spatial relationship equation is as follows: , The weaving speed satisfies the following expression: , The yarn drop point position expression is as follows: , in, is the angle of the yarn landing point in the core mold section coordinate system, is the angle of the intersection of the yarn and the guide ring in the guide ring coordinate system, is the eccentricity value, is the core mold radius, is the weaving speed of the yarn, is the guide ring radius, The spindle speed is mapped to the weaving speed on the core mold surface. is the pulling speed, For weaving time, Indicates the knitting time is The yarn drop point position at The spatial relationship equation established by the present invention accurately describes the relationship between the position of the yarn on the guide ring and the position of the landing point on the core mold, providing a theoretical basis for the simulation and prediction of the weaving process; the derived weaving speed expression reveals the speed distribution law of the yarn moving along the surface of the core mold, providing a basis for controlling the weaving density and fabric structure; the derived yarn landing point position expression directly guides the precise positioning of the yarn on the core mold, ensuring the accuracy and stability of the weaving process.

[0010] Optionally, the method of obtaining the braiding angle vector field based on the yarn landing point position expression and the homogenized surface grid includes: obtaining the desired braiding angle based on the yarn landing point position expression and the homogenized surface grid; obtaining the braiding angle vector field according to the desired braiding angle. The present invention accurately calculates the desired braiding angle by combining the position of the yarn landing point with the surface data of the homogenized surface grid, ensuring the precise control of the braiding angle and providing a basis for the stability and consistency of the fabric structure; the determined desired braiding angle provides a direct basis for the construction of the braiding angle vector field, so that the angle changes during the braiding process can be quantified and predicted, improving the controllability and predictability of the braiding process; the obtained braiding angle vector field intuitively shows the braiding angle distribution of the yarn on the core mold surface, improving the overall performance of the eccentric braiding process.

[0011] Optionally, the expression of the braiding angle vector field is as follows: , in, Indicates The weaving angle direction vector on the triangle patch, Indicates clockwise yarn, Indicates counterclockwise yarn, Indicates The projection vector of the center line on the triangle patch, For the The normal vector of the triangle, For the The desired braiding angle corresponding to the triangle patch is is a generalized rotation matrix. The present invention provides an accurate description of the braiding angle of the yarn on the core mold surface, so that the arrangement and interweaving mode of the yarn during the braiding process can be quantitatively analyzed, providing a scientific basis for optimizing the fabric structure and improving the braiding efficiency; the visual expression of the braiding angle vector field intuitively displays the distribution state of the yarn on the surface of complex special-shaped structural parts, which helps to better understand the braiding process, achieve precise control and adjustment, and thus improve the quality and performance of the product; through the analysis of the braiding angle vector field, the influence of different braiding parameters on the fabric structure and performance is predicted and evaluated, promoting the application and development of eccentric braiding technology in the field of automated braiding.

[0012] Optionally, optimizing the desired fabric structure on different regions of the core mold according to the weaving angle vector field includes: generating weaving angle reference lines for clockwise yarns and counterclockwise yarns according to the weaving angle vector field; extracting reference points through the weaving angle reference lines, wherein the reference points are the intersections of the weaving angle reference lines and the key planes of the reconstructed core mold; based on the positions of the reference points and the perimeters of the key sections where they are located, re-dividing the edges of the key sections and obtaining division results; and optimizing the desired fabric structures on different regions of the core mold according to the division results. The present invention realizes precise control of yarn weaving angles by generating weaving angle reference lines for clockwise and counterclockwise yarns, providing a reliable basis for constructing complex fabric structures; extracting the intersection of the weaving angle reference line and the key plane of the reconstructed core mold as the reference point not only simplifies the complexity of fabric structure design, but also ensures the uniformity and rationality of yarn distribution on key sections; the edge lines are re-divided based on the position of the reference point and the perimeter of the key section, optimizing the layout of the desired fabric structure in different areas of the core mold, which not only improves the performance of the fabric, but also meets the special requirements of special-shaped structural parts for the fabric structure.

[0013] Optionally, the inference generation of eccentric weaving process parameters through the expected fabric structure includes: obtaining the speed, trajectory and posture corresponding to all yarns through the expected fabric structure; performing weighted average calculation on the speed, trajectory and posture to obtain eccentric weaving process parameters. The present invention accurately obtains the speed, trajectory and posture of all yarns during the weaving process, provides detailed data support for the setting of process parameters, and ensures the stability and controllability of the weaving process; by performing weighted average calculation on the speed, trajectory and posture, the movement characteristics of different yarns are effectively integrated, so that the eccentric weaving process parameters finally obtained are more reasonable and accurate, fully reflecting the overall requirements of the fabric structure.

[0014] Optionally, the eccentric weaving process parameters satisfy the following expression: , in, is the pulling speed corresponding to the yarn, is the weight value corresponding to the yarn, is the center point position of the guide ring, is the normal vector of the guide ring, is the pulling speed under eccentric weaving process, is the weaving track position under the eccentric weaving process, This is the weaving trajectory posture under the eccentric weaving process. is the number of triangles on the clockwise yarn, represents clockwise yarn, represents counterclockwise yarn, , is the spatial coordinate. The present invention comprehensively considers multiple key factors such as the speed, trajectory and posture of the yarn, ensures the accuracy and stability of the weaving process, and provides reliable technical support for the manufacture of special-shaped structural parts; the process parameters are calculated by the weighted average method, which not only reflects the overall trend of the yarn movement, but also takes into account the local differences, so that the weaving results are more in line with the design requirements and improve the quality and performance of the product; this expression simplifies the calculation process of the eccentric weaving process parameters, improves the efficiency of the process design, and provides strong support for the rapid iteration and optimization of the weaving process.

[0015] In the second aspect, the present invention provides a weaving process reasoning system for special-shaped structural parts based on eccentricity theory, including an input device, a processor, an output device and a memory, wherein the input device, the processor, the output device and the memory are interconnected, wherein the memory is used to store a computer program, the computer program includes program instructions, the processor is configured to call the program instructions, and the system uses the said weaving process reasoning method for special-shaped structural parts based on eccentricity theory. The system can automatically generate eccentric weaving process parameters that meet the design requirements through precise calculation and reasoning, greatly improving the accuracy and efficiency of the weaving process; comprehensively considering multiple factors such as the speed, trajectory and posture of the yarn, ensuring the uniform distribution and reasonable interweaving of the yarn during the weaving process, thereby improving the quality and performance of the special-shaped structural parts; it has a high degree of flexibility and scalability, and can quickly adjust the process parameters according to different design requirements, providing strong technical support for the manufacture of special-shaped structural parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of a method for reasoning a knitting process of a special-shaped structural part based on the eccentricity theory according to an embodiment of the present invention; Figure 2 A schematic diagram of the main components of a braiding machine according to an embodiment of the present invention; Figure 3 A schematic diagram comparing a concentric vertical weaving process and an eccentric weaving process according to an embodiment of the present invention; Figure 4 A schematic diagram of a desired fabric structure optimization process according to an embodiment of the present invention; Figure 5 It is a schematic diagram of the reasoning process of eccentric weaving process parameters according to an embodiment of the present invention; Figure 6 A schematic diagram of a weaving experiment according to an embodiment of the present invention; Figure 7 A schematic diagram showing a comparison of knitting process parameters according to an embodiment of the present invention; Figure 8 Schematic diagram of the comparison of fabric structures with different weaving processes according to an embodiment of the present invention; Fig. 9 It is a structural schematic diagram of a weaving process reasoning system for special-shaped structural parts based on eccentricity theory according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details do not need to be adopted to implement the present invention. In other examples, in order to avoid confusing the present invention, known circuits, software or methods are not specifically described.

[0018] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or subcombination. In addition, it should be understood by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale.

[0019] See also Figure 1 The embodiment of the present invention provides a method for reasoning the knitting process of a special-shaped structural part based on the eccentricity theory, and the method comprises the following steps: S1. Obtain a three-dimensional model of a core mold of a special-shaped structural part.

[0020] In one embodiment, a three-dimensional model of the core mold of the special-shaped structural part is constructed using professional three-dimensional modeling software SolidWorks, and the three-dimensional model accurately reflects the actual shape and size of the core mold.

[0021] S2. Using the three-dimensional model, obtain a homogenized surface mesh of the key cross section of the core mold.

[0022] Among them, S2 includes the following steps: S21. Use the core mold 3D model to extract point cloud data.

[0023] In one embodiment, the constructed three-dimensional model is saved in STL format, which is a file format commonly used in the fields of three-dimensional printing, numerical simulation, etc., and contains geometric information of the model.

[0024] Furthermore, the ScanTo3D plug-in is used in SolidWorks to open the STL model in the form of a mesh file and save it in OBJ format. The OBJ format is a universal 3D model file format suitable for a variety of 3D processing software.

[0025] Furthermore, the PCL (Point Cloud Library) library is installed and configured. The PCL is an open source point cloud processing library that provides a wealth of point cloud processing algorithms and tools.

[0026] Furthermore, the OBJ file is converted into point cloud data using the PCL point cloud library mesh sampling tool and a point cloud file in PCD format is generated, wherein the point cloud file contains the three-dimensional coordinate information of each point in the point cloud.

[0027] S22. Perform orthogonal projection on the point cloud data to obtain the center line of the heterogeneous structural part.

[0028] In one embodiment, first, the extracted point cloud data is preprocessed, including removing noise points and filling missing parts to ensure the accuracy and completeness of the data.

[0029] Furthermore, according to the characteristics and needs of the heterogeneous structural member, the main extension direction of the structural member is selected as the orthogonal projection direction.

[0030] Furthermore, the preprocessed point cloud data is projected along a selected orthogonal direction, and each point in the projection will find its corresponding projection point on the projection plane to form a projected point set.

[0031] Furthermore, a mathematical algorithm is used to extract the center line from the projected point set. The mathematical algorithm includes a least square method and a Hough transform, which are used to identify and connect key features in the projected points, thereby depicting the center line of the structural component.

[0032] Furthermore, the extracted centerline is post-processed, including smoothing and removing redundant parts, to ensure its accuracy and aesthetics.

[0033] S23. Reconstruct the key cross-section of the core mold using the spatial relationship between the center line and the point cloud data.

[0034] In one embodiment, first, based on the extracted centerline data, the position of the centerline in the three-dimensional space is clarified.

[0035] Furthermore, according to the design requirements of the core mold, a specific cross-sectional position is selected, and the cross-sectional position and the center line are used as references to perform a slicing operation on the point cloud data, and the slicing operation extracts a point cloud subset that intersects with the selected cross-sectional area.

[0036] Furthermore, the sliced ​​point cloud subset is processed to extract the contour of the cross section, including the steps of filtering, segmentation and boundary identification of the point cloud.

[0037] Furthermore, the extracted contours are fitted using the least square method and curve fitting method to generate a smooth and accurate cross-sectional shape.

[0038] Furthermore, according to the fitted cross-sectional shape, combined with the overall design and functional requirements of the core mold, the key cross-section of the core mold is reconstructed.

[0039] S24. Connect the points of the key cross sections through a custom call sequence to generate a homogenized surface mesh.

[0040] In one embodiment, according to the three-dimensional modeling software, a calling sequence is customized according to the order and relationship of the point data, and the sequence will guide the software how to connect these points in sequence.

[0041] Furthermore, using connection tools or commands in the software, points on the key sections are connected according to a custom calling sequence to form a network consisting of line segments or curves.

[0042] Furthermore, a mesh generation tool or command in the software is used to preliminarily generate a surface mesh based on the connected points and networks.

[0043] Furthermore, the mesh optimization tool or plug-in in the software is used to optimize the initially generated mesh to make the mesh more uniform and smooth, thereby obtaining a homogenized surface mesh.

[0044] It should be noted that in most core molds, due to design reasons, there are redundant weaving features such as through holes and concave platforms in the three-dimensional model, resulting in uneven distribution of points on the core mold surface, thereby affecting the generation of weaving angles of various parts of the core mold three-dimensional model, further reducing the optimization accuracy of the desired fabric structure. Therefore, the present invention uses a model reconstruction algorithm to perform secondary processing on the core mold surface mesh.

[0045] S3. Based on the eccentric weaving theory and the homogenized surface grid, the weaving angle vector field is obtained.

[0046] Among them, S3 includes the following steps: S31. Based on the eccentricity theory, establish the spatial relationship equation.

[0047] The weaving process of special-shaped structural parts is shown in Figure 2. The weaving machine mainly includes two motion systems, namely the main drive system of the weaving machine and the weaving posture adjustment system. The main drive system enables the clockwise spindle and the counterclockwise spindle to drive the yarn to perform high-speed staggered motion. At the same time, the robot clamping core mold in the weaving posture adjustment system continues to advance in different postures. The yarn moving in the opposite direction on a large scale is woven into a mesh structure in the air, and then constrained by the guide ring, and finally forms a highly interwoven fabric in different directions on the surface of the core mold. Among them, the main drive system is composed of multiple servo motors and closed-loop gear transmission chains, and the weaving posture adjustment system is composed of one or more robots equipped with linear guides.

[0048] In the eccentric weaving theory, the vertical weaving process is first introduced, such as Figure 3 (a) shown.

[0049] Specifically, in the process of vertical weaving, the yarn landing point and the tangency of the outer contour of the core mold can be described by a mathematical relationship at any position, and the mathematical relationship is as follows: , in, is the pulling speed, is the weaving speed of the yarn, is the guide ring radius, is the core mold radius, is the convergence radius, is the initial convergence length, For braiding corners, For knitting time. Figure 3 As can be seen from (a), the yarns are evenly distributed around the core and all the yarns have the same rotation speed. Therefore, the preform has the same structure in the circumferential direction of the core, and it can be seen from the above relationship that when When the selection is appropriate, the size of the braiding angle during the braiding process is only related to the braiding speed and the pulling speed of the yarn. Under eccentric braiding conditions, due to the existence of the eccentricity value, the spindle speed is inconsistent with the circumferential deposition speed of the yarn after the spindle speed is mapped on the core mold surface, and changes with the change of the landing point position, such as Figure 3 (b) as shown.

[0050] In one embodiment, a spatial relationship equation is established according to the position of the yarn on the guide ring and the landing point position on the core mold under the eccentric knitting process, and the form is as follows: , in, is the angle of the yarn landing point in the core mold section coordinate system, It is the angle between the intersection of the yarn and the guide ring in the guide ring coordinate system, also called the braiding angle. is the eccentricity value, is the core mold radius, is the guide ring radius.

[0051] It should be noted that in the eccentric braiding process, the braiding angle affects the strength, elasticity, density and braiding efficiency of the braid. The desired braiding angle should be determined according to the specific braid type, purpose and required performance. Therefore, when designing the braiding process, these factors should be fully considered to obtain the best braiding effect.

[0052] S32. Perform time differential operation on the spatial relationship equation to obtain a weaving speed expression of the spindle speed mapped on the surface of the core mold.

[0053] Under eccentric weaving conditions, due to the existence of the eccentricity value, after the spindle speed is mapped on the core mold surface, the spindle speed is inconsistent with the circumferential deposition speed of the yarn and changes with the change of the landing point position.

[0054] In one embodiment, in order to obtain the weaving speed of the spindle speed under eccentric weaving mapped on the core mold surface, the step S31 , perform differential operations on time, and the expression is as follows: , in, The weaving speed is mapped from the spindle speed to the mandrel surface.

[0055] S33. According to the weaving speed expression, obtain the yarn landing point position expression.

[0056] In one embodiment, the angle of the yarn drop point in the core mold cross-section coordinate system is determined according to the knitting speed expression obtained in step S32 and the specific knitting speed obtained in the knitting process. .

[0057] Furthermore, the angle Substituting into the spatial relationship equation in step S31, the braiding angle is obtained .

[0058] In another embodiment, based on the eccentricity theory, using the knitting speed expression, an expression for the yarn drop point position under eccentricity is obtained, and the expression is as follows: , in, is the pulling speed, For weaving time, Indicates the knitting time is The yarn drop point position at is a constant.

[0059] S34. Based on the yarn drop point position expression and the homogenized surface grid, obtain the weaving angle vector field.

[0060] Wherein, S34 further comprises the following steps: S341. Obtain the desired braiding angle based on the yarn drop point position expression and the surface data of the homogenized surface grid.

[0061] In one embodiment, the braiding performance of the eccentric braiding process is designed by taking into account the strength, elasticity, density and braiding efficiency of the braided fabric.

[0062] Specifically, an eccentricity value is first set, and the patch data of the surface of the homogenized surface mesh is used, combined with the expressions in steps S31, S32 and S33, to solve the weaving angle, weaving speed and yarn drop point position of the mesh surface. It should be noted that the patch data refers to the various plane space data on the surface of the core mold three-dimensional model.

[0063] Furthermore, according to the braiding angle, the braiding speed and the yarn landing point position, the change state of the fabric structure on both sides of the eccentricity is measured, which involves fabric defects.

[0064] Furthermore, the sparseness of the inner and outer sides of the fabric structure is determined.

[0065] Furthermore, the eccentricity value is changed, and the above steps are repeated continuously until the surface landing points of the fabric structure surface sheet are evenly distributed. At this time, the eccentricity value is the expected eccentricity value.

[0066] Further, the desired eccentricity value is substituted into the braiding angle expression under the eccentricity condition in step S31 to solve the braiding angle, which is the desired braiding angle.

[0067] S342. Obtain a braiding angle vector field based on the desired braiding angle.

[0068] In one embodiment, according to step S341, desired braiding angle data on each triangular facet on the reconstructed uniformized surface mesh is obtained.

[0069] Further, a braiding angle vector field is generated according to the desired braiding angle data, and the expression of the braiding angle vector field is as follows: , in, Indicates The weaving angle direction vector on the triangle patch, Indicates clockwise yarn, Indicates counterclockwise yarn, Indicates The projection vector of the center line on the triangle patch, For the The normal vector of the triangle, For the The desired braiding angle corresponding to the triangle patch is is a generalized rotation matrix, and the expression of the generalized rotation matrix is ​​as follows: , in, For along Direction of the triangle normal vector, For along Direction of the triangle normal vector, For along Direction of the triangle normal vector, It means rotation. , , is the space coordinate.

[0070] S4. Optimize the desired fabric structure on different regions of the core mold according to the braiding angle vector field.

[0071] Among them, S4 includes the following steps: S41. Generate braiding angle reference lines for clockwise yarns and counterclockwise yarns according to the braiding angle vector field.

[0072] In one embodiment, first, the distribution and variation pattern of the braiding angle vector field are observed to determine the tilt direction and angle of the yarn.

[0073] Furthermore, mathematical tools (such as vector analysis) are used to quantitatively analyze the braiding angle vector field and extract the angle information of the yarn.

[0074] Furthermore, the yarns are divided into clockwise yarns and counterclockwise yarns according to their tilt directions. For clockwise yarns, their angle vectors should point to the clockwise part of the braiding angle vector field; for counterclockwise yarns, their angle vectors should point to the counterclockwise part.

[0075] Furthermore, for the clockwise yarn, a representative yarn is selected as the reference line, and the angle vector of the yarn should be able to reflect the overall tilt direction of the clockwise yarn. Similarly, for the counterclockwise yarn, a representative yarn is also selected as the reference line, and the angle vector of the yarn should be able to reflect the overall tilt direction of the counterclockwise yarn. The reference line is used to ensure that the yarn trajectory fluctuates around the desired braiding angle after optimization to avoid performance differences.

[0076] It should be noted that when selecting the reference line, factors such as the position, length, and inclination angle of the yarn can be considered to ensure that the reference line can accurately reflect the arrangement and weaving structure of the yarn.

[0077] S42. Extract a reference point through the braiding angle reference line, where the reference point is the intersection of the braiding angle reference line and the key plane of the reconstructed core mold.

[0078] In one embodiment, first, it is ensured that the braiding angle reference lines of the clockwise yarn and the counterclockwise yarn have been generated according to the braiding angle vector field.

[0079] Furthermore, the key planes of the reconstructed core mold are determined, and the key planes are important geometric feature planes or functional planes on the core mold. The positions and directions of these planes can be obtained through CAD models or actual measurements.

[0080] Furthermore, mathematical methods (such as vector operations) are used to calculate and obtain the intersection of the braiding angle reference line and the key plane of the reconstructed core mold.

[0081] S43. Based on the position of the reference point and the perimeter of the key section, the edge line of the key section is re-divided to obtain a division result.

[0082] In one embodiment, first, the precise coordinates of the reference points and the perimeter information of the key cross-sections are obtained. The information should be accurate and complete to facilitate subsequent analysis and division.

[0083] Furthermore, a suitable partitioning strategy is determined according to the shape and size of the key cross-section and the position of the reference point. The partitioning strategy should take into account the needs of subsequent analysis, design or manufacturing to ensure the practicality and accuracy of the partitioning result.

[0084] Furthermore, the location of the division point is calculated according to the perimeter of the key section and the division strategy, wherein the mathematical method of equidistant division and angle division is used to determine the specific location of the division point.

[0085] Furthermore, the calculated division points are connected in sequence to form new edges, and the edges should be continuous and smooth for subsequent analysis and use.

[0086] S44. Optimize the desired fabric structure on different regions of the core mold according to the division results.

[0087] In one embodiment, based on the division results obtained from the reference points and the perimeter of the critical cross-section, combined with step S3, the required fabric structure type is determined according to the functions and performance requirements of different areas of the core mold.

[0088] Furthermore, the fabric structure is optimized to improve its adaptability and performance, such as Figure 4 shown.

[0089] It should be noted that the purpose of optimization is to eliminate the uneven distribution of yarn spacing on the inner and outer sides of the curvature.

[0090] S5. Inferring and generating eccentric weaving process parameters through the desired fabric structure.

[0091] Among them, S5 includes the following steps: S51. Obtain the speed, trajectory and posture corresponding to all yarns through the desired fabric structure.

[0092] In one embodiment, the discrete points are The expected trajectories on all corresponding patches are solved for their positions mapped in the spindle motion space. ,like Figure 5 As shown. Among them, , For two different yarn drop positions, , is the coordinate point.

[0093] Furthermore, the yarn trajectory on the surface sheet is extended along the optimized desired fabric direction, and the intersection with the guide ring is , and forms the midpoint position of the guide ring , and the intersection with the spindle motion plane is .

[0094] Furthermore, the time, guide ring position and posture required for the same trajectory to be deposited on adjacent patches are extracted.

[0095] Furthermore, the pulling speed of each yarn is solved.

[0096] It should be noted that the movement speed of the spindle in each yarn is a fixed value.

[0097] S52. Perform weighted average calculation on the speed, the trajectory and the posture to obtain eccentric weaving process parameters.

[0098] In one embodiment, the speed, trajectory, and posture corresponding to all yarns are weighted and averaged to obtain the knitting process parameters under eccentric knitting. The expression of the knitting process parameters is as follows: , in, is the pulling speed corresponding to the yarn, is the weight value corresponding to the yarn, is the center point position of the guide ring, is the normal vector of the guide ring, is the pulling speed under eccentric weaving process, is the weaving track position under the eccentric weaving process, This is the weaving trajectory posture under the eccentric weaving process. is the number of triangles on the clockwise yarn, represents clockwise yarn, represents counterclockwise yarn, , is the space coordinate.

[0099] Furthermore, according to the expression of the weaving process parameters, the eccentric weaving process parameters are obtained.

[0100] In a specific embodiment, experiments were conducted using a Yunlu composite weaving equipment set, which included a 176-spindle weaving machine and a weaving posture adjustment system composed of a KUKA robot equipped with a linear guide rail, to verify the effectiveness of the eccentric weaving process reasoning method of the present invention. Figure 6 The upper half of the large curvature special-shaped structural part shown is a braided forming section, and the lower half is an auxiliary extension section designed for convenient clamping, and the lower half is not braided. The experiment also uses Zhongfu Shenying 12K T700 untwisted carbon fiber yarn for braiding, and the braiding equipment parameters are shown in Table 1.

[0101]

[0102] In this embodiment, the process parameters of the vertical weaving are first inferred by the traditional analytical method, and then the eccentric weaving process parameters are inferred by the eccentric weaving theory, and then the weaving experiment is carried out using the two weaving process parameters.

[0103] Specifically, Figure 6 As shown, the braiding angle measurement results and coverage measurement results are compared for the dark measurement section area on the mandrel. The traction trajectory and traction speed obtained by the two methods are shown in Figure 7, where the traction trajectory is represented by the relative motion of the guide ring and the mandrel, and the motion of the mandrel passing through the guide ring is converted into the motion of the guide ring passing through the mandrel.

[0104] from Figure 7 It can be seen that the traction trajectory is almost consistent with the center line of the core mold under the traditional concentric vertical process. Due to the existence of the convergence length, the trajectory is slightly longer than the center line of the core mold. However, there is a large difference between the traction trajectory and the center line under the eccentric weaving process. The curvature of the trajectory changes in order to optimize the local fabric in the preform, and the overall trajectory is offset by 38mm upward. At the same time, due to the existence of the convergence distance, the eccentric weaving trajectory optimizes the initial convergence distance, and the weaving speed is faster in the first half of the weaving, which speeds up the process from the initial state to the deposition state of the yarn. In the second half, it gradually stabilizes at 4mm / s, which is consistent with the speed obtained by the traditional analytical method.

[0105] The process parameters inferred by the two methods are used for weaving, and the fabric structure is as follows Figure 8 As shown. The process parameters of the vertical weaving process inferred by the traditional analytical method are based on the weaving of the center line of the core mold. Since the special-shaped structural part of the present invention is a large curvature curved tube, the deposition amount of the annular yarn of the core mold is the same, resulting in an abnormal fabric structure under different surface areas. On the inner side of the curvature, due to the small surface area, the fabric is squeezed and stacked; on the outer side of the curvature, due to the large surface area, the yarn is not enough to cover the entire core mold, resulting in fabric holes. Figure 7 It can be seen that under the concentric vertical process, the inner and outer braiding angles vary in the range of 55° to 65°, which is close to the expected braiding angle of 60°. However, the coverage rate shows a significant difference, with a difference of more than 35%. The inner and outer coverage rates of the eccentrically woven fabric are significantly improved, without fabric stacking and sparseness. The average difference in the inner and outer coverage rates is 10.9%, which is more than 24% lower than that of the traditional method. However, due to the non-uniform circumferential deposition of the fabric under the deposition mechanism, the accuracy of the braiding angle on the inner and outer sides of the curvature is reduced to a certain extent, and the maximum difference from the expected braiding angle occurs on the outer side of the curvature.

[0106] See also Fig. 9 , Fig. 9 The present invention is a schematic diagram of a system structure for reasoning a knitting process for a special-shaped structural part based on the eccentricity theory in an embodiment of the present invention. The system includes an input device, a processor, an output device, and a memory, wherein the input device, the processor, the output device, and the memory are interconnected, wherein the memory is used to store a computer program, the computer program includes program instructions, the processor is configured to call the program instructions, and the system uses the method for reasoning a knitting process for a special-shaped structural part based on the eccentricity theory.

[0107] In this embodiment, the input device is used to input basic parameters in the weaving process, including traction speed, eccentricity value, and spatial position data of the core mold surface, and the basic parameters are used to infer and generate weaving process parameters.

[0108] The processor has built-in various mathematical algorithms, including a weaving angle algorithm under eccentricity, a weaving speed algorithm, a yarn drop point position algorithm, a weaving angle vector field algorithm, a generalized matrix algorithm and a weaving process parameter algorithm.

[0109] The output device uses a display screen to display the calculation results processed by the processor.

[0110] The memory adopts a high-speed solid-state hard disk to store the basic parameters input by the input device and the calculation results processed by the processor. The memory has the characteristics of fast reading and writing speed, large capacity and high reliability, and can meet the needs of large data storage.

[0111] In summary, the present invention aims at the problem that fabric defects are prone to occur at complex geometric features in woven special-shaped structural parts, and proposes a weaving process parameter reasoning method and system based on the eccentric mechanism. The method analyzes the influence mechanism of the eccentric process on the fabric forming on the special-shaped structural parts, reveals the weaving principle and method for solving fabric defects, uniformly arranges the surface grids on the special-shaped structural parts based on the grid reconstruction model, proposes a weaving angle direction vector optimization method, and reversely infers the weaving trajectory and speed under the eccentric weaving process. The weaving process reasoning method proposed in the present invention is a new reasoning method different from the traditional analytical method, which is suitable for the core mold of special-shaped structural parts and is conducive to improving the weaving forming quality. After experimental verification, the process parameters generated by the reasoning of the present invention can completely eliminate the fabric defects at the complex geometric features of special-shaped structural parts, and the difference in the inner and outer coverage rates is reduced by more than 24%, breaking through the weaving posture constraints of the traditional weaving process, and providing a theoretical basis for the process planning software of the low-cost and fast automated weaving production line of large-sized special-shaped structural parts. Through precise calculation and reasoning, the system can automatically generate eccentric weaving process parameters that meet the design requirements, greatly improving the accuracy and efficiency of the weaving process; it comprehensively considers multiple factors such as the speed, trajectory and posture of the yarn to ensure the uniform distribution and reasonable interweaving of the yarn during the weaving process, thereby improving the quality and performance of special-shaped structural parts; it has high flexibility and scalability, and can quickly adjust process parameters according to different design requirements, providing strong technical support for the manufacture of special-shaped structural parts.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for reasoning the weaving process of special-shaped structural parts based on eccentricity theory, characterized in that: The method comprises the following steps: Obtain a three-dimensional model of the core mold of the special-shaped structural part; Using the three-dimensional model, a homogenized surface grid of a key cross section of the core mold is obtained; Based on the eccentric braiding theory and the homogenized surface grid, a braiding angle vector field is obtained; optimizing the desired fabric structure on different regions of the core mold according to the braiding angle vector field; Through the desired fabric structure, eccentric weaving process parameters are inferred and generated.

2. According to the eccentricity theory-based reasoning method for special-shaped structural parts weaving process, the method is characterized in that: The method of obtaining a homogenized surface mesh of a key cross section of the core mold by using the three-dimensional model comprises: Using the three-dimensional model, extracting point cloud data; Performing orthogonal projection on the point cloud data to obtain the center line of the heterogeneous structural part; Reconstructing the key cross-section of the core mold by using the spatial relationship between the center line and the point cloud data; The points of the key sections are connected through a custom calling sequence to generate a homogenized surface mesh.

3. The method for reasoning the knitting process of special-shaped structural parts based on eccentricity theory according to claim 1 is characterized in that: The method of obtaining the braiding angle vector field based on the eccentric braiding theory and the homogenized surface grid comprises: According to the position of the yarn on the guide ring and the landing point position on the core mold under the eccentric knitting process, a spatial relationship equation is established; Performing time differentiation operation on the spatial relationship equation to obtain a weaving speed expression; According to the knitting speed expression, an expression for the yarn drop point position is obtained; Based on the yarn drop point position expression and the homogenized surface grid, a braiding angle vector field is obtained.

4. The method for reasoning the knitting process of special-shaped structural parts based on eccentricity theory according to claim 3 is characterized in that: The spatial relationship equation is as follows: ， The weaving speed expression is as follows: ， The yarn drop point position expression is as follows: ， in, is the angle of the yarn landing point in the core mold section coordinate system, is the angle of the intersection of the yarn and the guide ring in the guide ring coordinate system, is the eccentricity value, is the core radius, is the weaving speed of the yarn, is the guide ring radius, The spindle speed is mapped to the weaving speed on the core mold surface. is the pulling speed, For weaving time, Indicates the knitting time is The yarn drop point position at is a constant.

5. The method for reasoning the knitting process of special-shaped structural parts based on eccentricity theory according to claim 3 is characterized in that: The obtaining of the braiding angle vector field based on the yarn drop point position expression and the homogenized surface grid comprises: Designing weaving performance based on the yarn drop point position expression and the homogenized surface grid; According to the design result of the braiding performance, a desired braiding angle is obtained; According to the desired braiding angle, a braiding angle vector field is obtained.

6. The method for reasoning the knitting process of special-shaped structural parts based on eccentricity theory according to claim 5 is characterized in that: The expression of the braiding angle vector field is as follows: ， in, Indicates The weaving angle direction vector on the triangle patch, Indicates clockwise yarn, Indicates counterclockwise yarn, Indicates The projection vector of the center line on the triangle patch, For the The normal vector of the triangle, For the The desired braiding angle corresponding to the triangle patch is is the generalized rotation matrix.

7. The method for reasoning the knitting process of special-shaped structural parts based on eccentricity theory according to claim 1 is characterized in that: Optimizing the desired fabric structure on different regions of the core mold according to the braiding angle vector field comprises: generating braiding angle reference lines of clockwise yarn and counterclockwise yarn according to the braiding angle vector field; Extracting a reference point through the braiding angle reference line, wherein the reference point is an intersection of the braiding angle reference line and a key plane of a reconstructed core mold; Based on the position of the reference point and the perimeter of the key section, the edge line of the key section is re-divided to obtain a division result; According to the division results, the desired fabric structures on different regions of the core mold are optimized.

8. The method for reasoning the knitting process of special-shaped structural parts based on eccentricity theory according to claim 1 is characterized in that: The generating of eccentric weaving process parameters by reasoning through the desired fabric structure includes: Obtaining the speed, trajectory and posture corresponding to all yarns through the desired fabric structure; The speed, the trajectory and the posture are weighted averaged to obtain eccentric knitting process parameters.

9. The method for reasoning the knitting process of special-shaped structural parts based on eccentricity theory according to claim 8 is characterized in that: The eccentric weaving process parameters satisfy the following expression: ， in, is the pulling speed corresponding to the yarn, is the weight value corresponding to the yarn, is the center point position of the guide ring, is the normal vector of the guide ring, is the pulling speed under eccentric weaving process, is the weaving track position under the eccentric weaving process, This is the weaving trajectory posture under the eccentric weaving process. is the number of triangles on the clockwise yarn, represents clockwise yarn, represents counterclockwise yarn, , is the space coordinate.

10. A special-shaped structural part weaving process reasoning system based on eccentricity theory, the system using a special-shaped structural part weaving process reasoning method based on eccentricity theory according to any one of claims 1 to 9, characterized in that: The system includes an input device, a processor, an output device and a memory, wherein the input device, the processor, the output device and the memory are connected to each other, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is configured to call the program instructions.

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