Rapid modeling method and system based on parameterization applied to sheet metal parts

Abstract

The invention relates to the technical field of parameter modeling, in particular to a parameterization rapid modeling method and system applied to sheet metal parts. The method comprises the following steps that a first processing module comprising a main contour axis, a bending line center line and a flange center line is established, feature region division is conducted according to forming geometric features, feature element intersection points are extracted and connected to form a second processing module, a forming structure is replaced with segmentation information and process information, compensation is conducted, and the forming geometric features are obtained. And finally generating a sheet metal part plane expansion geometric model. According to the method, a structured geometric framework comprising a main contour axis, a bending line center line and a flange center line is established, and intelligent feature point recognition and space positioning, multi-dimensional process parameter matching and replacement of a forming structure and accurate unfolding and bending compensation calculation are combined; high precision, high efficiency and high adaptability of parameterized rapid modeling of the sheet metal part are achieved, and the consistency and production efficiency of design and manufacturing are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of parametric modeling technology, and in particular to a method and system for rapid parametric modeling of sheet metal parts. Background Technology

[0002] Early sheet metal modeling methods primarily employed geometry-based modeling techniques, manually defining bend lines, flanges, and contour curves to create 3D models of sheet metal parts. While these methods achieved digitization, they suffered from drawbacks such as cumbersome modeling processes, low parametric levels, and difficulty in quickly adapting to changing design requirements. Parametric rapid modeling methods, on the other hand, systematically systematize the local geometric features and manufacturing process information of sheet metal parts, establishing model modules and automatically assembling and unfolding them according to rules. With a deeper understanding of sheet metal forming processes, and by incorporating key geometric features such as bend line centerlines and flange centerlines, multi-level modular modeling techniques have gradually developed, significantly improving design flexibility and accuracy.

[0003] However, existing modeling often treats the segmentation as a simple connection, ignoring the impact of the segmentation on the flange shape (such as double flanges, edge wrapping) and unfolding, resulting in inconsistencies between the unfolded drawing and the actual machining. Furthermore, if the intersection of the feature elements and the flange / bending line is not determined according to the rules and connected in sequence, self-intersection, gaps, or discontinuous boundaries may occur, thus affecting the accuracy of sheet metal modeling. Summary of the Invention

[0004] Therefore, it is necessary to provide a method and system for parametric rapid modeling of sheet metal parts to solve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, a parametric rapid modeling method for sheet metal parts is proposed, the method comprising the following steps: Step S1: Based on the proposed local geometric layout of the sheet metal parts, establish the first processing module, which includes the main contour axis, the center lines of each bending line and the center lines of each flange; Step S2: Based on the forming geometry of the sheet metal part, the first processing module is divided into feature regions to obtain several feature regions; Step S3: Determine the intersection points of the feature elements in each feature area with the corresponding flange centerline and bend line centerline, and connect the intersection points on them in a predetermined order according to the flange centerline and bend line centerline to form the second processing module; Step S4: Based on the proposed sheet metal part segmentation information and processing technology information, in the second processing module, the single flange at the segmentation point is replaced with the corresponding forming structure, and the forming structure is expanded and bent to obtain the sheet metal part planar unfolded geometric model.

[0006] This specification provides a system for rapid parametric modeling of sheet metal parts, used to execute the aforementioned method for rapid parametric modeling of sheet metal parts. This system includes: The initial modeling module is used to establish the first processing module based on the proposed local geometric layout of the sheet metal part. The first processing module includes the main contour axis, the center lines of each bending line and the center lines of each flange. The region division module is used to divide the first processing module into several feature regions based on the forming geometry of the sheet metal part. The intersection confirmation module is used to determine the intersection positions of the feature elements in each feature area with the corresponding flange centerline and bend line centerline, and connect the intersection points on them in a predetermined order of flange centerline and bend line centerline to form the second processing module. The compensation modeling module is used to replace the single flange at the segment with the corresponding forming structure in the second processing module according to the proposed sheet metal part segment information and processing technology information, and to perform unfolding compensation and bending compensation on the forming structure to obtain the sheet metal part planar unfolded geometric model.

[0007] The present invention has the following beneficial effects: First, by establishing a primary processing module in the initial stage, including the main contour axis, bending line centerline, and flange centerline, and utilizing the forming geometry of sheet metal parts to divide feature regions, a geometric data framework with a clear structural logic can be formed in the early stages of modeling. Combining the precise extraction and sequential connection of the intersection points of feature elements and centerlines to generate a second processing module ensures the consistency and traceability of geometric relationships during the modeling process, thereby significantly improving the accuracy and efficiency of parametric rapid modeling of sheet metal parts and reducing repetitive operations in traditional manual drawing.

[0008] Second, by intelligently identifying geometric feature points such as the endpoints of bending lines, the vertices of flange boundaries, and turning points, and combining this with the main contour axis projection method, a spatial correspondence between feature points and the flange centerline and bending line centerline was established, enabling the classification and sorting of feature elements. Utilizing multiple spatial positioning methods, including projection position, linear position, and directional relationships, the boundaries and relative positions of feature areas can be quickly determined, reducing manual judgment and alignment errors and ensuring the accurate transfer of geometric features in subsequent modeling steps.

[0009] Third, in the segmented processing stage, this invention achieves high adaptability replacement of a single flange structure by matching processing technology information with the forming structure library. Furthermore, it performs multi-dimensional screening based on process parameters such as forming temperature, processing speed, and pressure to ensure optimal process adaptability of the selected forming structure. Regarding unfolding and bending compensation, this invention accurately calculates the compensation amount based on actual geometric dimension changes, material thickness, and bending radius, effectively reducing the deviation between the produced product and the design dimensions, and significantly improving product consistency and manufacturing precision.

[0010] Fourth, before generating the planar unfolded geometric model, this invention introduces a local geometric arrangement update of the compensated formed structure. Point cloud data is acquired through prototype fabrication and 3D scanning. Surface reconstruction and planar unfolding techniques are used to digitally verify the actual prototype, achieving closed-loop comparison and optimization between the design model and the physical prototype. This process not only improves the matching degree between the model and actual production but also allows for the early detection and correction of design defects, reducing rework and production waste in later stages. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the steps involved in a parametric rapid modeling method for sheet metal parts. Figure 2 for Figure 1 A detailed flowchart illustrating the implementation steps of step S3. Figure 3 This is an undeveloped drawing of a sheet metal part based on a parametric rapid modeling method applied to sheet metal parts; Figure 4 This is a planar unfolded geometric model of a sheet metal part based on a parametric rapid modeling method applied to sheet metal parts; Figure 5 A functional module diagram based on a parametric rapid modeling system for sheet metal parts is provided in one embodiment of this application; The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0012] The technical method of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0013] Furthermore, the accompanying drawings are merely illustrative of the invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0014] It should be understood that although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0015] To achieve the above objectives, please refer to Figures 1 to 5 A method and system for parametric rapid modeling of sheet metal parts, the method comprising the following steps: Step S1: Based on the proposed local geometric layout of the sheet metal parts, establish the first processing module, which includes the main contour axis, the center lines of each bending line and the center lines of each flange; In one embodiment, reference may be made to Figure 3 In the sheet metal design phase, the proposed local geometric layout data of the sheet metal part is imported through CAD 3D modeling software (such as SolidWorks or UGNX), and the overall outline of the sheet metal part is extracted using geometric analysis algorithms, and the main outline axis is automatically generated. On this basis, the bending features existing on the sheet metal part are detected, and the corresponding bending line centerline is calculated and generated. At the same time, for existing flange structures, the flange centerline is calculated and generated based on the flange edge outline.

[0016] During the generation process, the first processing module mentioned above supports storing the extracted main contour axis, bending line centerline, and flange centerline in vector form, which facilitates subsequent geometric matching, positioning, and machining path planning. In this way, accurate geometric reference information can be obtained before sheet metal parts are formed, improving the accuracy and efficiency of subsequent manufacturing and inspection processes.

[0017] In another embodiment, taking the design project of a sheet metal part for an electrical cabinet door as an example, the local geometric layout model is opened using Siemens NX 12.0 software. The sheet metal part has dimensions of 1200mm × 600mm × 2mm and is made of Q235 cold-rolled steel plate. The outer edge of the sheet metal part is detected by the geometric feature extraction module to obtain the main contour point set. The system automatically calculates the axis of symmetry of the main contour and generates a main contour axis with a length of 1180mm and an accuracy of ±0.05mm.

[0018] Next, two 90° bends on the sheet metal part were detected, both with a bend radius of R=3mm and bend lengths of 300mm and 500mm respectively. The system automatically generated bend centerlines along the neutral layer of the bend features, with both centerlines displayed as blue dashed lines and marked with an angle of 90°. For the flange area on the left side of the sheet metal part, the system extracted the outer boundary of the flange and calculated the centerline parallel to the boundary. The flange width was 20mm, and the corresponding flange centerline length was 450mm, with an accuracy controlled within ±0.02mm. All generated main contour axes, bend centerlines, and flange centerlines were uniformly stored as DXF vector files and imported into the subsequent sheet metal unfolding and processing path planning module for automatic programming of laser cutting machines and CNC bending machines.

[0019] Step S2: Based on the forming geometry of the sheet metal part, the first processing module is divided into feature regions to obtain several feature regions; In one embodiment, the first processing module established in step S1 is input as reference data into the feature recognition module. Geometric analysis algorithms are used to identify forming features on the sheet metal part, including but not limited to bending areas, punching areas, flange areas, convex and concave forming areas, and planar areas. The system divides the first processing module into multiple feature regions based on the geometric boundaries and axis positions of the features. During region division, a geometric projection method based on the main contour axis and feature centerline is preferentially used to ensure seamless boundaries between feature regions. For feature regions that overlap or have continuous transitions, the system automatically adds transition buffers to facilitate smooth connection of subsequent processing paths and independent analysis of detected features. The divided feature regions are stored in vector data format and labeled with region type (e.g., "bending area," "punching area") for subsequent matching, processing technology arrangement, and detection scheme formulation.

[0020] In another embodiment, in the case of the electrical cabinet door sheet metal part in embodiment S1, the generated first processing module (DXF vector file) is imported into AutoCAD Mechanical 2022, and the feature area is divided by a self-developed geometric feature recognition plugin. The system first detects two bending center lines (bending lengths of 300mm and 500mm respectively), and divides the corresponding area along the outer boundary of the bending radius R=3mm to form two bending areas.

[0021] Next, four Φ20mm diameter punches were detected on the sheet metal surface. Each punch was delineated with a radius of +10mm, creating four independent punch areas. On the left flange structure, a process buffer zone of ±2mm was added along the flange centerline, extending half the flange width (10mm) to form a 450mm long flange area. After removing these feature areas, the remaining undefined planar portion was defined as the planar area, used for subsequent painting processes and flatness checks.

[0022] The partitioning results are saved in a vector layered manner: the bending area is a red solid line layer, the punching area is a green dashed line layer, the flange area is a blue dotted line layer, and the flat area is a black solid line layer. Finally, it is saved as a DXF file for CNC bending machines, punching machines and testing equipment to realize regional-level process path planning and testing strategy generation.

[0023] Step S3: Determine the intersection points of the feature elements in each feature area with the corresponding flange centerline and bend line centerline, and connect the intersection points on them in a predetermined order according to the flange centerline and bend line centerline to form the second processing module; In one embodiment, after the feature region is divided, the system performs a traversal inspection of the geometric elements (including feature boundary lines, punching contours, and concave / convex forming edges) within each feature region, and uses a geometric intersection algorithm to calculate the coordinates of the intersection points between each element and the center line of the flange and the center line of the bend line to which it belongs. For cases with multiple intersection points, the system sorts them according to a preset order of the flange center line and the center line of the bend line (e.g., from left to right or from top to bottom), and connects these intersection points sequentially to form a second processing module with a continuous geometric reference path. This second processing module is used for subsequent process reference transfer, processing path optimization, and inspection calibration. Its generation method ensures that the geometric relationship between the flange area and the bend area remains consistent during processing and inspection.

[0024] In another embodiment, in the case of the electrical cabinet door sheet metal part in embodiment S2, the DXF file with completed feature area division is imported into SolidWorks 2023 and a custom macro program is run. The program first detects the intersection points A1 (coordinates: X=150.00mm, Y=50.00mm) and A2 (coordinates: X=450.00mm, Y=50.00mm) of the boundary of the bending area 1 (length 300mm) and the center line of the bending line; and detects the intersection points B1 (X=700.00mm, Y=50.00mm) and B2 (X=1200.00mm, Y=50.00mm) in the bending area 2 (length 500mm).

[0025] In the flange area (450mm in length), the intersections of the flange edge features and the flange centerline, C1 (X=50.00mm, Y=600.00mm) and C2 (X=500.00mm, Y=600.00mm), were detected. The system connected these points in a predetermined sequence: flange centerline intersection first, then bending line centerline intersection, from C1→C2→A1→A2→B1→B2, generating a continuous geometric path, which was defined as the second processing module.

[0026] The path file is saved as "PATH_MODULE_2.DXF" and imported into the AMADA HG-8025 CNC bending machine control system for automatic optimization of bending sequence and workpiece datum alignment; it is also imported into the online inspection system to realize scanning measurement according to the intersection sequence, thereby improving inspection efficiency and accuracy.

[0027] Step S4: Based on the proposed sheet metal part segmentation information and processing technology information, in the second processing module, the single flange at the segmentation point is replaced with the corresponding forming structure, and the forming structure is expanded and bent to obtain the sheet metal part planar unfolded geometric model.

[0028] In one embodiment, reference may be made to Figure 4 First, the system accesses the segment information database to determine the location of each segment and its corresponding flange type within the second processing module. When a single flange structure is detected at a segment, it is replaced with the target forming structure (e.g., rolled edge, stepped bend, concave-convex reinforcing ribs, etc.) based on process parameters. During the replacement process, the system automatically calculates the geometric unfolding compensation value and bending compensation value of the forming structure based on the processing technology information: unfolding compensation is used to correct the length change after the forming structure is unfolded; bending compensation is used to correct the angular deviation caused by bending radius, plate thickness, and material elastic recovery. The system then unfolds the replaced and compensated geometric data as a whole, generating a planar unfolded geometric model of the sheet metal part, and saves it in CAD vector format for direct use by equipment such as CNC blanking machines and laser cutting machines.

[0029] In another embodiment, in the case of the electrical cabinet door sheet metal part in embodiment S3, the segment information database shows that the flange centerline C1–C2 segment on the second processing module path is a single 90° right-angle flange with a length of 450mm. The processing requirement is to replace it with a rolled edge forming structure (rolled edge radius R=5mm, rolled edge height 12mm). After reading this segment information, the system calls the forming replacement function built into AMADASheetWorks 2023 to replace the right-angle flange with a rolled edge structure, and calculates the unfolding compensation amount based on the material (cold-rolled steel plate, thickness t=1.5mm, yield strength 210MPa). Compensation amount for unfolding: Increase in unfolded length of rolled edge = π × (R + t) / 2 ≈ 10.99 mm; Bending compensation amount: Based on K factor 0.33, the bending deduction length is calculated to be 1.57mm.

[0030] The aforementioned compensation values ​​were automatically applied to the geometric model, resulting in a rolled edge segment with an unfolded length of 450mm + 10.99mm – 1.57mm = 459.42mm. The final unfolded model was saved as CABINET_DOOR_FLAT_2023.DXF and sent to the TRUMPF TruLaser 3030 laser cutting machine, achieving a seamless transition from geometric design to material preparation.

[0031] As an example of the present invention, reference is made to... Figure 2 As shown, step S3 in this example includes: Step S31: Within each feature region, extract all feature elements and their corresponding flange centerline and bend line centerline; Step S32: Using the main contour axis as a reference, determine the intersection point of the feature element with the flange centerline and the bending line centerline; Step S33: Arrange the intersection points on the flange centerline and the bending line centerline according to the order of their projection on the main contour axis; Step S34: Connect the intersections in a predetermined order to form a continuous geometric path; establish a second processing module based on the geometric path.

[0032] In one embodiment, after the feature region is divided, a geometric feature extraction algorithm is used to traverse the vector elements within the region, including boundary lines, punching contours, forming lines, and reinforcing rib contours. A data structure for the flange centerline and bending line centerline associated with each feature element is established for subsequent intersection analysis. The main contour axis is defined as a global geometric reference system. A two-dimensional geometric intersection algorithm is used to calculate the intersection point of each feature element with its corresponding centerline, and its precise position in the global coordinate system is recorded. The coordinates of each intersection point are projected onto the main contour axis to obtain a one-dimensional projection value. The intersection points are then sorted from smallest to largest according to the projection value, forming an ordered list of intersection points. The sorted intersection points are connected according to the process-defined order rules (e.g., flange centerline priority, then bending line order) to generate a continuous geometric path without self-intersections. This path is then imported into the second processing module as the core reference geometry for subsequent process compensation, unfolding, and processing path planning.

[0033] In another embodiment, for example, in the design of a cabinet side panel sheet metal part with dimensions of 1200mm × 600mm, the main contour axis is defined as the center reference line along the long side of the panel. The system detects two flange center lines (F1, F2) and one bend center line (B1) in feature region 1; and one flange center line (F3) and two bend center lines (B2, B3) in feature region 2. The geometric intersection calculation results are as follows: The intersection point P1 of F1 and the edge of the punch (X=150.00mm, Y=50.00mm). The intersection point P2 of F2 and the outer contour (X=450.00mm, Y=50.00mm). The intersection point P3 of B1 and the outline of the reinforcing rib (X=700.00mm, Y=50.00mm). The intersection point P4 of F3 and the outer contour (X=950.00mm, Y=50.00mm). Point P5 (X=1100.00mm, Y=50.00mm) is the intersection of B2 and the edge of the groove. The intersection point P6 of B3 and the outer contour (X=1150.00mm, Y=50.00mm). The projection values ​​of these intersection points on the main contour axis are as follows: P1(150.00)→P2(450.00)→P3(700.00)→P4(950.00)→P5(1100.00)→P6(1150.00). The intersection points are arranged in projection order and connected into a continuous geometric path according to the rule of "flange priority, bending second": P1→P2→P4→P3→P5→P6. This geometric path, as the core reference path of the second processing module, is saved as SIDE_PANEL_PATH.DXF and subsequently imported into the programming software of the CNC bending machine to realize automatic bending processing and inspection datum transfer according to the intersection point sequence.

[0034] Preferred methods for extracting feature elements include: Within each feature region, the start and end points of the bend line, the vertex of the flange boundary, and the turning point are identified as geometric feature points. Calculate the projected position of each feature point on the main contour axis as the reference coordinate for spatial positioning, and determine the spatial correspondence between the feature point and the flange centerline and the bending line centerline based on the projection relationship of the reference coordinates. Geometric feature points are categorized using spatial correspondence, and feature points of the same category are sorted according to their projection order on the corresponding center line to obtain feature elements.

[0035] In one embodiment, after the feature region is divided, the CAD vector analysis module is invoked to traverse the bending line segments and extract its start and end points; the endpoints and inflection points where the rate of curvature change is greater than a set threshold are extracted from the flange boundary curve, and the above point set is defined as a geometric feature point set. The main contour axis is set as a global reference line, and the perpendicular bisector formula from a point to a line is used to calculate the projection point of each geometric feature point on the main contour axis, and the distance from the projection point to the axis start point is recorded as a reference coordinate. By comparing the overlap between the feature point projection position and the centerline projection range, it is determined which flange centerline or bending line the feature point belongs to, and the corresponding association is established in the feature data structure. All feature points belonging to the same centerline are arranged in ascending order of reference coordinate values ​​and sequentially labeled with their serial numbers to form a feature element sequence of the centerline, which serves as the basic data for subsequent geometric path construction and process planning.

[0036] In another embodiment, taking an 800mm × 500mm sheet metal door panel as an example, its main contour axis is set as the central axis along the long side. In feature area A, the system detects a flange boundary (F1) and a bend line (B1). Through CAD geometric analysis: the start and end points of bend line B1 are Q1 (100.00, 80.00) and Q2 (400.00, 80.00), the vertex of flange boundary F1 is V1 (50.00, 80.00), and the turning points of flange boundary F1 are T1 (60.00, 120.00) and T2 (90.00, 150.00). The projection calculation results (with the main contour axis starting point X = 0.00mm as a reference) are as follows: Q1 → Projected coordinates 100.00mm; Q2 → Projected coordinates 400.00mm; V1 → Projected coordinates 50.00mm; T1 → Projected coordinates 60.00mm; T2 → Projected coordinates 90.00mm; Spatial correspondence determination: The projection ranges of Q1 and Q2 completely match the projection interval of the bending line B1 → classified as B1; the projection ranges of V1, T1, and T2 match the projection interval of the flange F1 → classified as F1. Therefore, the sorting results are as follows: for B1: Q1(100.00)→Q2(400.00), and for F1: V1(50.00)→T1(60.00)→T2(90.00). The final feature element sequence is: feature element of bending line B1 = {Q1, Q2}, feature element of flange F1 = {V1, T1, T2}.

[0037] Preferably, step S32 includes the following steps: Step S321: Determine the relative position of each feature element in the sheet metal part based on its projection position on the main contour axis; Step S322: Within the feature area where the feature element is located, select the flange centerline and the bend line centerline that are closest to the projected position of the feature element; Step S323: Calculate the spatial coordinates of the intersection point between the feature element and the center line of the flange and the center line of the bending line based on the relative position, and obtain the intersection point position.

[0038] In one embodiment, a geometric calculation module is used to obtain the actual spatial coordinates of the feature element and project them onto the main contour axis. The distance between the projection point and the starting point of the main contour axis is calculated as a relative position parameter. In the feature region data structure, the projection range of all flange centerlines and bend line centerlines is extracted. By comparing the distance between the projection position of the feature element and the projection range of each centerline, the centerline with the smallest distance and satisfying the condition of overlapping projection ranges is selected. The projection point of the feature element is extended perpendicularly along the plane containing the flange centerline or bend line, and the intersection of the perpendicular line and the centerline is obtained. The two-dimensional or three-dimensional coordinates of the intersection point are recorded as the intersection point position for subsequent path connection and expansion compensation calculations.

[0039] In another embodiment, a sheet metal cover plate with a length of 1000mm and a width of 600mm can be used as an example, with the main contour axis set as the center line along the long side. In feature region B, the system detects a flange center line F2 (starting point (200.00, 100.00), ending point (800.00, 100.00)) and a bending line B2 (starting point (300.00, 300.00), ending point (700.00, 300.00)). The actual coordinates of feature element P1 are (320.00, 280.00). Calculate the projection position of P1 on the main contour axis. Assuming the equation of the main contour axis is y = 300.00 mm (horizontal line), the foot of the perpendicular from P1 to this axis is P1' = (320.00, 300.00), and its length from the starting point of the main contour axis (0.00, 300.00) is 320.00 mm. Therefore, the relative position of P1 is 320.00 mm. The projection range of the flange centerline F2 is 200.00 mm to 800.00 mm; the projection range of the bend line B2 is 300.00 mm to 700.00 mm. The projection position of P1 at 320.00 mm falls within the projection range of F2 and B2, and its distance from the starting point of B2 is the smallest (20.00 mm). The system determines that the bend line closest to P1 is B2, and the flange centerline closest to P1 is F2. Draw a perpendicular line from the projection point P1' of P1 along the plane containing the flange centerline F2, and find the intersection point coordinates as (320.00, 100.00); draw a perpendicular line from P1' along the plane containing the bend line B2, and find the intersection point coordinates as (320.00, 300.00). The final intersection point positions are: the intersection with the flange centerline F2: CF(320.00, 100.00), and the intersection with the bend line B2: CB(320.00, 300.00). This intersection point data will be used as the input for subsequent geometric path connection (step S34) to ensure that the path construction matches the actual forming features of the sheet metal.

[0040] Preferably, step S321 includes the following steps: Step S3211: Obtain the three-dimensional coordinates of each feature element; Step S3212: Project the three-dimensional coordinates onto the reference plane where the main contour axis is located, and calculate the coordinates of the projection point of the three-dimensional coordinates on the reference plane; Step S3213: Determine the linear position and orientation of the feature element relative to the main contour axis based on the coordinates of the projection point; spatially locate the feature element using the linear position and orientation to confirm the boundary of the feature region where the feature element is located; Step S3214: Sort the projection positions of feature elements using the feature region boundaries to determine the relative positions of feature elements in the sheet metal part.

[0041] In one embodiment, a 3D scanner or CAD 3D model reading module is used to collect the 3D spatial coordinate data of various feature elements (such as the start and end points of bending lines, flange boundary vertices, etc.) on the sheet metal part, forming a 3D coordinate set of feature elements. The reference plane containing the main contour axis is determined (usually the plane of the unfolded sheet metal part or a specific processing reference plane). An orthogonal projection transformation from point to plane is applied to map the 3D coordinates to the 2D reference plane, and the 2D coordinates of the projection point of each feature element are calculated and recorded. The distance from the projection point to the starting point of the main contour axis is calculated to obtain the linear position; simultaneously, vector analysis is used to determine the direction of the feature element relative to the axis (left or right, front or back) to confirm its spatial orientation. Based on the preset boundary coordinates of each feature region, the projection points are classified and sorted by region to ensure that feature elements are arranged in an orderly manner within their respective feature regions, providing a clear spatial hierarchy for subsequent path construction.

[0042] In another embodiment, taking a sheet metal side panel as an example, the sheet metal part has dimensions of 1200mm × 700mm. The main contour axis is defined as a straight line along the center line of the long side, and the reference plane is the unfolded plane of the sheet metal part (XY plane, Z axis vertically upward). The three-dimensional coordinates of a certain feature element are acquired by a 3D scanner as P(850.00, 350.00, 20.00), where Z=20.00mm indicates that the point is 20mm above the unfolded plane. The projection operation in step S3212 is performed to orthogonally project point P onto the reference plane to obtain projection point P'(850.00, 350.00, 0.00). The linear distance from projection point P' to the starting point (0, 350.00) of the main contour axis is calculated, yielding a distance of 850.00 mm. Simultaneously, it is determined whether P' is located to the left (Y-axis less than 350.00) or right (Y-axis greater than 350.00) of the axis. Here, 350.00 is the same as the Y-coordinate of P', so it is considered to be directly on the axis. Based on the preset feature area boundaries of the sheet metal part (e.g., area A is 0–600 mm X-axis, area B is 600–1200 mm), P' is assigned to area B. All feature element projection points within area B are sorted according to their X-axis values ​​from smallest to largest, ensuring that the relative positions of all feature points in this area are clear and orderly. The sorting result serves as the basis for constructing feature paths and calculating compensation in subsequent steps, ensuring the accuracy of geometric processing and the rationality of the processing sequence.

[0043] Preferably, in step S4, replacing the single flange at the segment with the corresponding formed structure within the second processing module, and performing unfolding compensation and bending compensation on the formed structure, includes: Based on the proposed sheet metal part segment information, identify the single flange structure at each segment location in the second processing module, and determine the range of flange segments that need to be replaced; Select the corresponding segmented forming structure based on the proposed processing technology information; The single flange structure is replaced with the corresponding segmented formed structure to obtain the replaced formed structure; The unfolding and bending compensation of the formed structure are performed by calculating the changes in the planar unfolded dimensions of the replaced formed structure.

[0044] In one embodiment, by analyzing segmentation information, traversing the path of the second processing module, detecting existing single flange segments, and marking their start and end positions and lengths as replacement ranges. Based on material properties, plate thickness, and customer process requirements, an applicable forming structure type, such as hemming, stepped bending, flanging, or reinforcing ribs, is automatically selected from the forming structure library, and its specific parameters are obtained. In the geometric model, the three-dimensional parameters of the selected forming structure replace the original single flange geometric data, forming a new geometric segment with forming characteristics. Based on the geometric characteristics of the forming structure, combined with material elasticity, bending radius, and bending coefficient, the corresponding unfolded length correction value and bending angle correction value are calculated, and the planar unfolded dimensions of the forming structure are adjusted to ensure the processing accuracy of blanking and bending.

[0045] In another embodiment, for a sheet metal box side panel, the segmentation information of its second processing module indicates that the flange located in the length range of 300mm to 500mm is a single 90° bend flange. The system calls the processing technology information database and selects the forming structure corresponding to this segment as a "rolled edge" structure, with a rolled edge radius R=4mm, a rolled edge height H=10mm, and the material being cold-rolled steel sheet with a thickness t=1.2mm. In the geometric model, the single bend flange in this 300mm to 500mm range is replaced with a rolled edge structure, and its three-dimensional geometry is adjusted to form a rolled edge profile that meets the process requirements. Calculation of unfolding compensation: The increase in the planar unfolding length of the rolled edge is approximately... Based on the material's springback coefficient and K-factor, the calculated bending compensation length is approximately 1.8 mm, and the angle compensation is 0.5 degrees. The final planar unfolded dimension of the replaced structure is approximately 13.9 mm longer than the original flange length, ensuring that the laser cutting dimensions meet the dimensional accuracy requirements after forming.

[0046] Of particular importance, the calculation of the changes in the planar unfolded dimensions of the replaced formed structure to compensate for the unfolding and bending of the formed structure also includes: Read the original planar unfolding data; The geometric data of the replaced 3D shaped structure is meshed to generate the replaced 3D mesh data; the replaced 3D mesh data is then parametrically unfolded to generate the initial planar unfolded data. The initial planar unfolding data is compared with the original planar unfolding data point by point to generate planar dimension change data; Calculate the local scaling factor for planar dimension variation data; The initial planar unfolded data is geometrically scaled and corrected using local scaling factors to generate compensated planar unfolded data. The bending correction amount data is obtained by performing bending back calculation on the compensated planar unfolded data; the bending sequence and fixture constraints are matched with the bending correction amount data to generate bending compensation process data. Formatting of CNC / process ports based on bending compensation process data.

[0047] In one embodiment, the two-dimensional unfolded model data of the sheet metal part before structural replacement is retrieved from the design database. The file format is DXF or STEP. The data read includes: a set of two-dimensional contour coordinate points, bending line positions and angle annotations, positioning holes, boundary constraints, and process cut information. The replaced formed structure is output as a three-dimensional solid model (.STEP or .IGES format) by CAD 3D modeling software (such as CATIA or UGNX). The solid surface is discretized into a mesh using a triangulation algorithm (such as the CGAL library). The mesh edge length is preferably 0.2mm ± 0.05mm to ensure the accuracy of the unfolding calculation while controlling the computational load. It should be noted that during meshing, the outer contour boundary line must be strictly fitted to the original CAD curve, and the mesh density should be increased to refine the bending lines and feature ribs to ensure local unfolding accuracy. A parametric unfolding algorithm based on energy minimization (such as LeastSquares Conformal Maps, LSCM) can be used to flatten the three-dimensional mesh surface onto a two-dimensional plane to generate initial planar unfolding data. The following constraints need to be set during the unfolding process: keep the key reference points (such as the center of the positioning hole) in the same position before and after unfolding; control the error of the outer contour length within ±1mm; use partition unfolding for local high curvature areas and stitch them together in a two-dimensional plane, and save the unfolding result as a two-dimensional point set file (.TXT) and a visualization DXF file.

[0048] Point-by-point coordinate matching is performed between the initial planar unfolded data and the original planar unfolded data. The matching method is as follows: boundary points, bending line points, and feature points are matched one-to-one according to topological order. For irregular regions, the nearest neighbor matching method is used. The size difference of each pair of corresponding points is calculated, and the difference data is saved as a planar size change data table. A heat map is plotted to represent the stretching or contraction trend of each region. The local scaling factor is calculated for each grid cell. ;in, This is the side length of the cell during the initial unfolding. The scaling factor data is stored in matrix form with coordinate indexes to correspond to the original unfolded side length, which facilitates subsequent scaling correction.

[0049] Use CAD secondary development interfaces (such as AutoCAD LISP, CATIA CAA, or Python OCC) to batch read planar dimension change data and perform local scaling corrections on the initial unfolded model: If >1 indicates stretching, which needs to be followed. Shrink; if <1 indicates contraction, which needs to be corrected. Method. After correction, generate compensated planar unfolded data, and then perform a global error verification with the original design to ensure that the maximum error does not exceed ±0.3mm. Read the compensated planar unfolded data and material parameters (thickness t, yield strength). Rebound coefficient ), calculate the springback compensation amount according to the bending theory formula: Where R is the bending radius. The following values ​​are calculated for each bending line: bending angle correction (accurate to 0.1°); bending line position correction (accurate to 0.1mm).

[0050] Based on the corrected bending data, a bending compensation process table is generated by matching it with the bending sequence and fixture constraints in the process library. The process table data is then formatted into NC code that can be directly called by the CNC bending machine, or exported as an XML process file that can be recognized by the MES system.

[0051] Preferably, the forming structure for the corresponding segments is selected based on the proposed processing technology information, including: Obtain the proposed processing technology information, which includes segment length, forming temperature, processing speed, and pressure parameters; The formed structure is divided into intervals based on the segment length to ensure that the error of each segment length does not exceed ±2mm, and the process parameter association attributes of each segment are marked. Based on the forming temperature and pressure parameters, the system matches the preset structure types in the forming structure library to obtain the forming structure matching results. The structure types include the mold cavity shape, material flow path, and reinforcing rib arrangement scheme. The matching tolerance is within ±5%. By using the processing speed to filter the process parameter correlation attributes of the forming structure matching results, the optimal forming structure for the corresponding segment is obtained.

[0052] In one embodiment, a detailed set of machining process parameters for the current sheet metal part design is obtained from the process management database. This includes the length range of each segment, the set value of the forming temperature, the processing speed, and the required pressure. The segment lengths are precisely divided, and corresponding process parameter labels are assigned to each segment to ensure that the interval division meets the length accuracy requirements of the process specifications. Based on the process parameters, a fuzzy matching algorithm is used to search for mold and structural design schemes that meet the temperature and pressure requirements in the forming structure library, and the set of forming structures that best matches the set conditions is selected. Combined with the processing speed requirements, the initially matched structural schemes are further screened to eliminate structures that are not suitable for high-speed or slow-speed processing. Finally, the forming structure that best matches the overall process parameters and has processing stability is selected.

[0053] In another embodiment, for a sheet metal bending segment with a length of 200mm, the proposed processing information is as follows: segment length: 200mm ± 2mm, forming temperature: 180℃, processing speed: 30 pieces / hour, applied pressure: 1500KN. Based on the above segment length, the design interval is precisely divided to ensure that the error is controlled within ±2mm, and this segment is marked as "Segment A". The forming structure library is searched for structure types that match the forming temperature of 180℃ and the pressure of 1500KN. The screening results include: Structure X: mold cavity A, material flow path B, reinforcing rib arrangement scheme C, matching degree 98% (error 2%); Structure Y: mold cavity D, material flow path E, reinforcing rib arrangement scheme F, matching degree 93% (error 7%). According to the matching tolerance requirement (within ±5%), Structure Y is eliminated, and Structure X is retained. By screening the process parameters of structure X in combination with a processing speed of 30 pieces / hour, it was confirmed that structure X is suitable for this speed range and has good processing stability. Finally, structure X was determined to be a segmented "segment A" forming structure, achieving a precise match between design and process parameters.

[0054] Of particular importance, the methods for constructing the shaped structure library also include: Information on sheet metal samples of different material types was collected, including material grade, yield strength, elongation, thickness range and surface treatment state, and mechanical response curves under different forming temperatures and pressures were obtained through standardized tests. Under standardized test conditions, mold cavity forming tests were conducted on each material sample. The shape of the mold cavity, the material flow path, and the geometric parameters of the reinforcing ribs after forming were recorded. The corresponding point cloud data were generated using a three-dimensional scanning device. Establish a data index relationship for each test result according to material type, mold cavity shape, material flow path and reinforcing rib arrangement scheme, and record the corresponding segment length, forming temperature, processing speed and pressure parameters for each sample; The collected point cloud data is subjected to feature extraction and normalization to generate structural feature vectors that can be directly used for matching operations, and the feature vectors are bound and stored with process parameters. Based on the allowable matching tolerance range in actual processing, each piece of data in the forming structure library is labeled with tolerance and version numbered so as to enable automatic calling and iterative updates during rapid modeling.

[0055] In one embodiment, the collected sheet metal sample information includes: material grade (e.g., SPCC, 6061-T6, etc.), yield strength, elongation, thickness range, and surface treatment state (e.g., galvanizing, spraying, phosphating, etc.). Using standardized testing equipment such as tensile testing machines and impact testing machines, mechanical response curves (stress-strain curves, hardening curves, etc.) of each sample are obtained under different forming temperatures (e.g., room temperature, 200℃, 350℃) and pressure conditions (e.g., 50MPa, 100MPa, 200MPa). Under standardized test conditions, mold cavity forming tests are performed on each material sample. During the test, the mold cavity shape (e.g., U-shape, V-shape, ribbed plate, etc.), material flow path (feed direction, flow distribution), and geometric parameters of the reinforcing ribs after forming (height, width, rib spacing, etc.) are recorded. Point cloud data of the formed part surface is collected using a 3D scanning device (laser scanner or structured light scanner).

[0056] The test results are indexed according to material type, mold cavity shape, material flow path, and reinforcing rib arrangement. For each sample, the corresponding segment length, forming temperature, processing speed, and pressure parameters are recorded, forming a searchable data structure. Feature extraction (e.g., geometric curvature distribution, rib cross-sectional contour features) and normalization (uniform size scale, coordinate system alignment) are performed on the collected point cloud data to generate structural feature vectors that can be directly used for matching calculations. These feature vectors are then bound to the corresponding process parameters and stored in the forming structure library. Based on the allowable matching tolerance range in actual processing (e.g., forming size ±5%, process parameters ±3%), tolerance annotations and version numbers are assigned to each data entry in the forming structure library to enable automatic retrieval, parametric replacement, and iterative updates in subsequent rapid modeling.

[0057] Preferably, the compensation for unfolding and bending of the formed structure by the change in the planar unfolded dimensions of the replaced formed structure includes: Based on the geometry of the replaced formed structure, confirm the planar unfolded dimension parameters; Based on the difference between the unfolded dimensions and the design dimensions, determine the unfolding compensation amount of the formed structure; Based on the material thickness and bending radius of the replaced formed structure, confirm the bending compensation value; The formed structure is compensated by expanding the compensation amount and bending the compensation value.

[0058] In one embodiment, 3D geometric modeling software is used to accurately measure the replaced formed structure and calculate its two-dimensional unfolded dimensions in its unbent state, including the lengths of each side, the arc length, and the connection angles. The calculated unfolded dimensions are compared with the original design dimensions to obtain dimensional differences, which serve as the basis for unfolding compensation and are used to adjust subsequent material cutting and processing parameters. Combining the material's physical properties and the processing bending radius, and based on a bending compensation model (such as the K-factor model, inner radius compensation model, etc.), dimensional correction values ​​during the bending process are calculated. The unfolding compensation amount and the bending compensation value are accumulated and applied to the two-dimensional unfolded model of the formed structure to correct the dimensions and angles, generating a compensated structure that meets the processing accuracy requirements.

[0059] In another embodiment, for a replaced sheet metal flange forming structure, the material thickness is 1.5mm and the bending radius is 5mm. Through 3D modeling calculations, the two-dimensional unfolded dimensions of the replaced forming structure are 400mm long and 150mm wide; the design dimensions are 390mm long and 145mm wide. The calculated unfolding compensation is: length direction unfolding compensation = 400mm - 390mm = +10mm; width direction unfolding compensation = 150mm - 145mm = +5mm. Based on the material thickness of 1.5mm and the bending radius of 5mm, using the K-factor model, the bending compensation value is calculated to be 2.2mm. Adding the unfolding compensation and bending compensation values ​​together, the final compensated unfolded dimensions are: length direction compensated dimension = 390mm + 10mm + 2.2mm = 402.2mm; width direction compensated dimension = 145mm + 5mm + 2.2mm = 152.2mm. The compensated dimensions of the formed structure are used to guide laser cutting and bending processes, ensuring that the dimensional accuracy of the formed parts meets the design requirements.

[0060] Preferably, before obtaining the planar unfolded geometric model of the sheet metal part, the following steps are also included: The local geometric arrangement of the sheet metal part is updated by updating the local geometric arrangement of the sheet metal part after compensation of the forming structure. Based on the updated local geometry of the sheet metal parts, a sheet metal part sample is made, and point cloud data of the sheet metal part sample is collected using a 3D scanning device to obtain the 3D point cloud data of the sheet metal parts. The surface reconstruction and planar unfolding of the 3D point cloud data are performed to obtain the planar unfolded geometric model of the sheet metal part.

[0061] In one embodiment, the forming structure parameters, after unfolding and bending compensation, are used to replace or adjust the corresponding geometric regions in the original sheet metal part design, reconstructing the local geometric arrangement of the sheet metal part to ensure that the design reflects the actual compensation results. Based on the updated local geometric arrangement, a sheet metal part sample is generated through processes such as CNC laser cutting and bending. A high-precision laser 3D scanner or structured light scanner is used to scan the sample surface from multiple angles to obtain a comprehensive 3D point cloud dataset. Point cloud processing software is used to filter, register, generate meshes, and fit surfaces to complete the 3D surface reconstruction. Subsequently, based on the sheet metal part material and processing parameters, planar unfolding calculations are performed to generate a 2D planar unfolded model that conforms to the actual forming dimensions.

[0062] In another embodiment, for a sheet metal box side panel, the local flange contour was updated with compensated forming structural dimensions. The system inputs the compensated dimensions into CAD design software, updates the local geometric arrangement, and generates new design drawings. Using the updated geometric arrangement, a 1.2mm thick cold-rolled steel sheet is processed using a laser cutting machine and bent into shape using a bending machine to prepare a sheet metal sample. A high-precision laser 3D scanner is used to scan the sample, achieving a scanning resolution of 0.05mm, acquiring point cloud data of approximately 1 million points on the sample surface. Point cloud processing software (such as Geomagic, PolyWorks, etc.) is used to denoise and register the point cloud data, constructing a 3D mesh surface model of the sample. Using professional unfolding software, the 3D surface is unfolded in a plane based on material thickness, bending radius, and compensation parameters to generate a 2D unfolded geometric model of the sheet metal part.

[0063] like Figure 5 The diagram shown is a functional module diagram of a parametric rapid modeling system for sheet metal parts provided in an embodiment of the present invention.

[0064] The parametric rapid modeling system 100 for sheet metal parts described in this invention can be installed in an electronic device. Depending on the functions implemented, the parametric rapid modeling system 100 for sheet metal parts may include a preliminary modeling module 101, a region division module 102, an intersection point confirmation module 103, and a compensation modeling module 104. The module described in this invention can also be called a unit, which refers to a series of computer program segments that can be executed by the processor of an electronic device and can perform a fixed function, and which are stored in the memory of the electronic device.

[0065] The initial modeling module 101 is used to establish a first processing module based on the proposed local geometric layout of the sheet metal part, wherein the first processing module includes the main contour axis, the center lines of each bending line and the center lines of each flange; The region division module 102 is used to divide the first processing module into several feature regions based on the forming geometric features of the sheet metal parts. The intersection confirmation module 103 is used to determine the intersection positions of the feature elements in each feature area with the corresponding flange center line and bending line center line, and connect the intersection points on them in a predetermined order of flange center line and bending line center line to form a second processing module. The compensation modeling module 104 is used to replace the single flange at the segment with the corresponding forming structure in the second processing module according to the proposed sheet metal part segment information and processing technology information, and to perform unfolding compensation and bending compensation on the forming structure to obtain the sheet metal part planar unfolding geometric model.

[0066] In detail, the modules described in this embodiment of the invention, based on the parametric rapid modeling system 100 for sheet metal parts, employ the same methods as described above. Figure 1 The techniques described herein are the same as those used in the parametric rapid modeling method for sheet metal parts, and can produce the same technical effects, so they will not be elaborated here.

[0067] Therefore, the embodiments should be considered as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the application are intended to be included within the invention.

[0068] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A method for rapid parametric modeling of sheet metal parts, characterized in that, Includes the following steps: Step S1: Based on the proposed local geometric layout of the sheet metal parts, establish the first processing module, which includes the main contour axis, the center lines of each bending line and the center lines of each flange; Step S2: Based on the forming geometry of the sheet metal part, the first processing module is divided into feature regions to obtain several feature regions; Step S3: Determine the intersection points of the feature elements in each feature area with the corresponding flange centerline and bend line centerline, and connect the intersection points on them in a predetermined order according to the flange centerline and bend line centerline to form the second processing module; Step S4: Based on the proposed sheet metal part segmentation information and processing technology information, in the second processing module, the single flange at the segmentation point is replaced with the corresponding forming structure, and the forming structure is expanded and bent to obtain the sheet metal part planar unfolded geometric model.

2. The method for rapid parametric modeling of sheet metal parts according to claim 1, characterized in that, Step S3 includes the following steps: Step S31: Within each feature region, extract all feature elements and their corresponding flange centerline and bend line centerline; Step S32: Using the main contour axis as a reference, determine the intersection point of the feature element with the flange centerline and the bending line centerline; Step S33: Arrange the intersection points on the flange centerline and the bending line centerline according to the order of their projection on the main contour axis; Step S34: Connect the intersections in a predetermined order to form a continuous geometric path; establish a second processing module based on the geometric path.

3. The method for rapid parametric modeling of sheet metal parts according to claim 2, characterized in that, Methods for extracting feature elements include: Within each feature region, the start and end points of the bend line, the vertex of the flange boundary, and the turning point are identified as geometric feature points. Calculate the projected position of each feature point on the main contour axis as the reference coordinate for spatial positioning, and determine the spatial correspondence between the feature point and the flange centerline and the bending line centerline based on the projection relationship of the reference coordinates. Geometric feature points are categorized using spatial correspondence, and feature points of the same category are sorted according to their projection order on the corresponding center line to obtain feature elements.

4. The method for rapid parametric modeling of sheet metal parts according to claim 2, characterized in that, Step S32 includes the following steps: Step S321: Determine the relative position of each feature element in the sheet metal part based on its projection position on the main contour axis; Step S322: Within the feature area where the feature element is located, select the flange centerline and the bend line centerline that are closest to the projected position of the feature element; Step S323: Calculate the spatial coordinates of the intersection point between the feature element and the center line of the flange and the center line of the bending line based on the relative position, and obtain the intersection point position.

5. The method for rapid parametric modeling of sheet metal parts according to claim 4, characterized in that, Step S321 includes the following steps: Step S3211: Obtain the three-dimensional coordinates of each feature element; Step S3212: Project the three-dimensional coordinates onto the reference plane where the main contour axis is located, and calculate the coordinates of the projection point of the three-dimensional coordinates on the reference plane; Step S3213: Determine the linear position and orientation of the feature element relative to the main contour axis based on the coordinates of the projection point; spatially locate the feature element using the linear position and orientation to confirm the boundary of the feature region where the feature element is located; Step S3214: Sort the projection positions of feature elements using the feature region boundaries to determine the relative positions of feature elements in the sheet metal part.

6. The method for rapid parametric modeling of sheet metal parts according to claim 1, characterized in that, In step S4, within the second processing module, the single flange at the segment is replaced with the corresponding formed structure, and the formed structure undergoes unfolding compensation and bending compensation, including: Based on the proposed sheet metal part segment information, identify the single flange structure at each segment location in the second processing module, and determine the range of flange segments that need to be replaced; Select the corresponding segmented forming structure based on the proposed processing technology information; The single flange structure is replaced with the corresponding segmented formed structure to obtain the replaced formed structure; The unfolding and bending compensation of the formed structure are performed by calculating the changes in the planar unfolded dimensions of the replaced formed structure.

7. The method for rapid parametric modeling of sheet metal parts according to claim 6, characterized in that, Based on the proposed processing technology information, the corresponding segmented forming structures are selected, including: Obtain the proposed processing technology information, which includes segment length, forming temperature, processing speed, and pressure parameters; The formed structure is divided into intervals based on the segment length to ensure that the error of each segment length does not exceed ±2mm, and the process parameter association attributes of each segment are marked. Based on the forming temperature and pressure parameters, the system matches the preset structure types in the forming structure library to obtain the forming structure matching results. The structure types include the mold cavity shape, material flow path, and reinforcing rib arrangement scheme. The matching tolerance is within ±5%. By using the processing speed to filter the process parameter correlation attributes of the forming structure matching results, the optimal forming structure for the corresponding segment is obtained.

8. The method for rapid parametric modeling of sheet metal parts according to claim 6, characterized in that, Compensation for the unfolding and bending of the formed structure is achieved by adjusting the planar unfolded dimensions of the replaced formed structure, including: Based on the geometry of the replaced formed structure, confirm the planar unfolded dimension parameters; Based on the difference between the unfolded dimensions and the design dimensions, determine the unfolding compensation amount of the formed structure; Based on the material thickness and bending radius of the replaced formed structure, confirm the bending compensation value; The formed structure is compensated by expanding the compensation amount and bending the compensation value.

9. The method for rapid parametric modeling of sheet metal parts according to claim 8, characterized in that, Before obtaining the planar unfolded geometric model of the sheet metal part, the following steps are also included: The local geometric arrangement of the sheet metal part is updated by updating the local geometric arrangement of the sheet metal part after compensation of the forming structure. Based on the updated local geometry of the sheet metal parts, a sheet metal part sample is made, and point cloud data of the sheet metal part sample is collected using a 3D scanning device to obtain the 3D point cloud data of the sheet metal parts. The surface reconstruction and planar unfolding of the 3D point cloud data are performed to obtain the planar unfolded geometric model of the sheet metal part.

10. A parametric rapid modeling system for sheet metal parts, characterized in that, For executing the parametric rapid modeling method for sheet metal parts as described in claim 1, the parametric rapid modeling system for sheet metal parts includes: The initial modeling module is used to establish the first processing module based on the proposed local geometric layout of the sheet metal part. The first processing module includes the main contour axis, the center lines of each bending line and the center lines of each flange. The region division module is used to divide the first processing module into several feature regions based on the forming geometry of the sheet metal part. The intersection confirmation module is used to determine the intersection positions of the feature elements in each feature area with the corresponding flange centerline and bend line centerline, and connect the intersection points on them in a predetermined order of flange centerline and bend line centerline to form the second processing module. The compensation modeling module is used to replace the single flange at the segment with the corresponding forming structure in the second processing module according to the proposed sheet metal part segment information and processing technology information, and to perform unfolding compensation and bending compensation on the forming structure to obtain the sheet metal part planar unfolded geometric model.

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