Preform optimization method and system for seal bar assembly wrinkle suppression

Abstract

The application discloses a preforming optimization method and system for seal strip assembly wrinkle suppression, and relates to the technical field of seal strip forming processing. The method comprises the following steps: a three-dimensional scanning vehicle body mounting area is performed, and a stress-free fitting space three-dimensional curve is extracted; springback compensation is performed in combination with a neutral layer position and material springback characteristics to generate a preforming target curve; an arc target is set based on the curve, an extrusion die pressure distribution runner is optimized, and a semi-finished product obtains a corresponding arc; a heat setting mold is set according to the curve, the semi-finished product is heated, pressure maintained and cooled, the arc is fixed, and a preformed seal strip is obtained. The technical problems of appearance and sealing performance defects caused by the following factors are solved: the outer side of the seal strip is lifted away from the joint during the assembly bending process due to the linear state of the extrusion section, the inner side is extruded and wrinkled, and the assembly stress is uneven. The technical effects of eliminating the wrinkles, lifting and springback after assembly, stabilizing the sealing performance and improving the assembly quality are achieved.

Description

Technical Field

[0001] This invention relates to the field of sealing strip forming and processing technology, specifically to a preforming optimization method and system for suppressing wrinkles during sealing strip assembly. Background Technology

[0002] With the development of the automotive industry and the increasing demands of consumers for vehicle quality, body sealing strips have become increasingly important in automobile manufacturing. Sealing strips not only prevent the ingress of dust and moisture but also significantly impact noise isolation and aerodynamic performance. Therefore, the installation precision and assembly quality of sealing strips directly affect the overall performance of the vehicle. In recent years, with the diversification of automotive designs, especially the increasing complexity of body structure and curved surface designs, traditional sealing strip assembly processes often result in assembly wrinkles and stress deformation in certain areas, such as the C-pillar of the door and windows, severely affecting sealing performance and assembly quality.

[0003] In traditional sealing strip production, sealing strips are often produced as preliminary strip-shaped semi-finished products through extrusion molding. Because the shape of the sealing strip requires a high degree of adaptability to the curved surfaces of the vehicle body, especially in the C-pillar area of ​​the door, where the vehicle body geometry is complex and the bending radius is small, the sealing strip needs to undergo multiple bending and splicing processes. However, traditional production processes cannot fully consider the material's springback characteristics, the precise geometry of the vehicle body, and the deformation and stress distribution of the sealing strip material. This often leads to wrinkles, warping, or inner wrinkles in the sealing strip during assembly, thus affecting its functionality and aesthetics. Summary of the Invention

[0004] This application provides a pre-forming optimization method and system for suppressing wrinkles in sealing strip assembly. It solves the technical problems of appearance and sealing performance defects caused by the outer side lifting and separation, inner side extrusion wrinkling, and uneven assembly stress during the assembly bending process when the sealing strip is installed on the complex curved surface of the vehicle body, due to the straight state of the extrusion section. It achieves the technical effect of matching the sealing strip with the installation trajectory in a stress-free bonding state through pre-forming design based on the spatial curve of the vehicle body, eliminating wrinkles, lifting and rebound after assembly, stabilizing sealing performance, and improving assembly quality.

[0005] The first aspect of this application provides a preforming optimization method for suppressing wrinkles in sealing strip assembly, the method comprising:

[0006] By 3D scanning the target installation area of ​​the vehicle body, a spatial 3D curve is extracted as the center line of the target installation trajectory. The spatial 3D curve represents the ideal fit space of the sealing strip under stress-free conditions. Based on the center line of the target installation trajectory, calculations and rebound compensation are performed using the neutral layer position of the sealing strip cross-section and the material rebound characteristics to generate a pre-formed target curve. An initial curvature target is set based on the pre-formed target curve, and the pressure distribution flow channel parameters of the extrusion die are optimized. The external flow channel resistance of the extrusion die is configured using the optimized pressure distribution flow channel parameters to obtain a semi-finished sealing strip with the initial curvature target. A heat-setting mold is set according to the pre-formed target curve, and the semi-finished sealing strip with the initial curvature target is placed in the heat-setting mold for heating, pressure holding, and cooling to fix the initial curvature and obtain a pre-formed sealing strip.

[0007] A second aspect of this application provides a preforming optimization system for suppressing wrinkles in sealing strip assembly, the system comprising:

[0008] Curve Extraction Module: By scanning the target installation area of ​​the vehicle body in three dimensions, a three-dimensional spatial curve is extracted as the center line of the target installation trajectory. The three-dimensional spatial curve represents the ideal fit space of the sealing strip under stress-free conditions. Springback Compensation Module: Based on the center line of the target installation trajectory, combined with the neutral layer position of the sealing strip cross-section and the material springback characteristics, calculations and springback compensation are performed to generate a pre-formed target curve. Parameter Optimization Module: Based on the pre-formed target curve, an initial curvature target is set, and the pressure distribution flow channel parameters of the extrusion die are optimized. The external flow channel resistance of the extrusion die is configured using the optimized pressure distribution flow channel parameters to obtain a semi-finished sealing strip with the initial curvature target. Semi-finished Product Processing Module: A heat-setting mold is set according to the pre-formed target curve. The semi-finished sealing strip with the initial curvature target is placed in the heat-setting mold for heating, pressure holding, and cooling to fix the initial curvature and obtain a pre-formed sealing strip.

[0009] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0010] First, a 3D scan of the installation area of ​​the vehicle body sealing strip is performed to obtain the true spatial geometry of the area, and the spatial centerline representing the sealing strip is extracted from it. Then, considering the position of the neutral layer of the sealing strip cross-section and the material's springback characteristics after bending, this centerline is calculated and compensated to generate a pre-formed target curve that the sealing strip should possess before assembly. Next, using the pre-formed target curve as a benchmark, the initial curvature required for the semi-finished sealing strip is determined, and the flow channel structure of the extrusion die is optimized to ensure that the flow rate and pressure distribution during extrusion meet the pre-bending requirements, thus directly obtaining an extruded semi-finished product with an initial curvature. Then, a corresponding heat-setting mold is designed according to the pre-formed target curve. The semi-finished product is placed in the mold for heating, pressure holding, and cooling, allowing its curvature to be precisely solidified. Finally, a pre-formed sealing strip that highly matches the vehicle body installation trajectory is obtained, ensuring that the sealing strip perfectly fits the vehicle body and effectively avoiding deformation problems caused by material springback. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of a preforming optimization method for suppressing wrinkles in sealing strip assembly, provided in an embodiment of this application.

[0013] Figure 2 This is a schematic diagram of a preform optimization system for suppressing wrinkles in sealing strip assembly, provided in an embodiment of this application.

[0014] Figure labeling: Curve extraction module 11, springback compensation module 12, parameter optimization module 13, semi-finished product processing module 14. Detailed Implementation

[0015] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0016] Example 1, as Figure 1 As shown, this application provides a preforming optimization method for suppressing wrinkles in sealing strip assembly, the method including:

[0017] By scanning the target installation area of ​​the vehicle body in three dimensions, a three-dimensional spatial curve is extracted as the center line of the target installation trajectory. The three-dimensional spatial curve represents the ideal fit space of the sealing strip under stress-free conditions.

[0018] In this embodiment, a three-dimensional optical scanning device, such as a laser scanner or a structured light scanner, is first used to perform a high-precision three-dimensional scan of the target installation areas, such as the C-pillar, side door frame, and door edge of the vehicle body, to obtain the geometric shape data of the actual installation area of ​​the sealing strip on the vehicle body. During the scanning process, reasonable scanning angles, supplementary lighting angles, and scanning paths are set to ensure complete coverage of data for key parts such as R-angles, turning areas, and straight sections. After scanning, point cloud processing software is used to register, fuse, and denoise the original data to reconstruct a continuous vehicle body installation surface model. Subsequently, a series of vertical sections are set along the installation direction of the sealing strip, and the surfaces in the installation surface model are densely sectioned to extract the curve contours on each section. For each section contour, the corresponding geometric center point is calculated, and all section center points are fitted and smoothed to form a continuous spatial three-dimensional curve. This spatial three-dimensional curve represents the spatial centerline of the sealing strip when it is in an ideal fit with the vehicle body surface under stress-free conditions, reflecting the spatial trajectory of the sealing strip under ideal installation posture, and can be used as the basic input data for subsequent springback compensation and pre-forming design.

[0019] Furthermore, by 3D scanning the target installation area on the vehicle body, a spatial 3D curve is extracted as the center line of the target installation trajectory, including:

[0020] The target installation area on the vehicle body is segmented according to the influence of assembly wrinkles, including an R-angle area, a straight transition area, and a regular straight section. Scanning paths and parameters are configured for the R-angle area, the straight transition area, and the regular straight section, with the scanning parameters including at least a scanning angle and a supplementary lighting angle. Based on the scanning parameters, scanning data for each target installation partition is obtained, and the scan data is fused and denoised to reconstruct a continuous installation surface model. The installation surface model is densely sectioned along a preset cross-sectional direction to obtain a series of cross-sectional contours. For each cross-sectional contour, the center point corresponding to the neutral layer position of the sealing strip installation is calculated. The center points corresponding to the series of cross-sectional contours are fitted and smoothed to generate a continuous three-dimensional spatial curve, which serves as the center line of the target installation trajectory.

[0021] Preferably, to accurately obtain the ideal fit trajectory of the sealing strip on the vehicle body, the target installation area of ​​the vehicle body is first divided according to the degree of bending and geometric change characteristics, based on the areas where wrinkles or stress concentrations may occur during the assembly process. This results in an R-angle region, a straight transition region, and a regular straight section. The R-angle region is an area with small curvature that is prone to wrinkles; the straight transition region is an area that gradually transitions from the R-angle to the straight section; and the regular straight section is an area with relatively regular geometry. Subsequently, based on prior experience, scanning paths and scanning parameters are set for the geometric characteristics of each region. These scanning parameters include at least the scanning angle and the supplementary lighting angle. For example, in the R-angle region, a denser scanning path and a wider coverage of the scanning angle are usually required to ensure that subtle curvature changes in this area are captured. In the straight transition region and the regular straight section, the scanning angle and the supplementary lighting angle are adjusted according to the surface morphology to ensure uniform light incidence and stable reflection information, thereby improving the point cloud quality. Subsequently, based on the configured scanning path and parameters, scanning operations are performed on each target installation partition, obtaining 3D point cloud data describing the morphology of each partition. This point cloud data is then imported into point cloud processing software for global registration and fusion, forming a continuous dataset across all partitions within a unified coordinate system. Next, preprocessing operations such as denoising, filtering, and hole repair are performed on the fused point cloud to eliminate virtual points caused by scanning errors and lighting, thereby reconstructing a structurally complete and smooth vehicle body installation surface model. After obtaining the installation surface model, a sectioning path is set along the installation direction of the sealing strip, and the surface is densely sectioned according to a preset cross-sectional direction, such as perpendicular to the installation direction, resulting in a series of uniformly distributed cross-sectional profiles along the installation path. These profiles reflect the true geometric shape of the vehicle body installation area at various locations. For each cross-sectional profile, based on the stress characteristics and cross-sectional structure during actual installation of the sealing strip, the position of the neutral layer corresponding to that cross-section is calculated, and the geometric center point that best represents the sealing strip's contact center is determined. Finally, the center points corresponding to all cross-sectional contours are fitted and smoothed according to the installation sequence. To eliminate the influence of local noise points and ensure the continuity and smoothness of the curve, B-spline fitting or least squares curve smoothing algorithm can be used to generate a continuous, smooth, and accurate three-dimensional spatial curve that reflects the actual installation trajectory of the vehicle body. This three-dimensional spatial curve will serve as the target installation trajectory centerline for subsequent preforming calculations and springback compensation, laying the foundation for effectively suppressing assembly wrinkles and appearance deformation.

[0022] Furthermore, calculating the center point corresponding to the location of the neutral layer where the sealing strip is installed includes:

[0023] Obtain the cross-sectional model of the sealing strip to be installed, which includes its snap-fit ​​structure, sealing lip structure, and material distribution information; calculate the theoretical neutral layer offset when bending deformation occurs under the curvature conditions corresponding to the current cross-sectional profile based on the structural and material properties of the cross-sectional profile; perform position compensation on the geometric center point of the cross-sectional profile based on the theoretical neutral layer offset to generate a compensated center point, wherein the calculation weight of the theoretical neutral layer offset is higher than that of the conventional straight section for the cross-sectional profile with R-angle.

[0024] Optionally, to obtain a center point that accurately reflects the installation trajectory of the sealing strip under bending conditions, a precise cross-sectional model of the sealing strip to be installed is first acquired. This cross-sectional model can be imported from CAD design drawings or extrusion die design data and includes structural information such as the sealing strip's snap-fit ​​structure, sealing lip structure, main adhesive area, and reinforcing skeleton. It also includes the distribution and material properties of the rubber material in each area, such as differences in modulus, hardness, and thickness at different locations, for subsequent neutral layer position analysis of bending behavior. Subsequently, based on the local curvature conditions of the current cross-sectional profile on the vehicle body, the bending state of the sealing strip at that location is analyzed. Specifically, by combining the radius of curvature of the cross-sectional profile with the sealing strip cross-sectional model, a mechanical model of the sealing strip's bending deformation under these curvature conditions is established. Based on this model, the strain distribution of the sealing strip cross-section in different regions on the inner and outer sides during bending is calculated. Combined with the material's elastic modulus distribution, the equilibrium point of the strain moment acting on the cross-section is comprehensively solved, thereby determining the actual offset of the theoretical neutral layer under bending conditions. This theoretical neutral layer offset represents the spatial offset direction and magnitude of the neutral layer relative to the geometric center point of the cross-section under bending conditions. Subsequently, based on the calculated theoretical neutral layer offset, position compensation is performed on the geometric center point of each cross-sectional profile. During the compensation process, the offset is superimposed along the principal normal direction of the cross-section to the geometric center point, making the compensated center point closer to the neutral position of the sealing strip under stress in the actual assembled bending state, thus reflecting the true fitting posture of the sealing strip. To ensure higher accuracy in neutral layer estimation in areas with drastic curvature changes, differentiated weights are set for different regions when calculating the offset. In the R-angle region, due to the smaller radius of curvature and significant bending strain, the nonlinear increase in the tension on the outer side and the compression on the inner side of the sealing strip leads to a greater degree of neutral layer offset. Therefore, for the cross-section in the R-angle region, the calculation weight of the theoretical neutral layer offset is higher than that of the conventional straight section, thus making the compensated center point more accurately reflect its true stress deformation. For the straight section and the region of the gentle curve, a lower weight is assigned to make the compensation smoother and avoid the fitting error caused by excessive offset. Through the above process, a series of center points after neutral layer compensation can be obtained. These center points can accurately depict the ideal fitting trajectory of the sealing strip under the actual assembly bending state, providing a reliable data basis for subsequent target installation trajectory centerline fitting and preform curve generation.

[0025] Based on the target installation trajectory centerline, and combined with the neutral layer position of the sealing strip cross-section and the material rebound characteristics, calculations and rebound compensation are performed to generate a pre-formed target curve.

[0026] In one embodiment, to ensure the sealing strip is in a stress-free fit after assembly, the extracted target installation trajectory centerline of the vehicle body is first used as the basic data. This target installation trajectory centerline represents the spatial geometric path of the sealing strip under ideal fit and no external force. Subsequently, combining the neutral layer position of the sealing strip cross-section, material properties, and curvature characteristics of the assembly area, curvature rebound compensation analysis is performed on multiple micro-segments discretized from the target installation trajectory centerline to calculate the curvature of the sealing strip after rebound compensation in each micro-segment. Then, to ensure the smoothness of the compensation, the curvature of continuous micro-segments is reconstructed, which eliminates local discretization errors and obtains a continuous and smooth spatial curve. This reconstructed spatial curve is used as the pre-forming target curve of the sealing strip. This pre-forming target curve reflects the preset geometric shape of the sealing strip during extrusion and shaping, ensuring that when subsequently assembled onto the vehicle body, the material can accurately fit the vehicle body surface after natural rebound, without warping, wrinkling, or gaps. This provides a precise basis for subsequent optimization of the extrusion die flow channel and design of the heat-setting mold.

[0027] Furthermore, based on the target installation trajectory centerline, and combined with the neutral layer position of the sealing strip cross-section and the material springback characteristics, calculations and springback compensation are performed to generate a pre-formed target curve, including:

[0028] Obtain the rebound characteristic parameters of the sealing strip material, including one or more of the following: elastic modulus, yield strength, coefficient of thermal expansion, and stress relaxation coefficient; discretize the center line of the target installation trajectory into continuous micro-segments; based on the rebound characteristic parameters, perform target curvature rebound compensation analysis on each micro-segment to obtain the target curvature after rebound compensation for each micro-segment; reconstruct a continuous spatial curve using the target curvature after rebound compensation calculated from all micro-segments, as the pre-formed target curve.

[0029] Preferably, to ensure stress-free adhesion after the sealing strip is assembled onto the vehicle body, the rebound characteristic parameters of the EPDM or TPV material used in the sealing strip are first obtained, including one or more of the following: elastic modulus, yield strength, coefficient of thermal expansion, and stress relaxation coefficient. These rebound characteristic parameters serve as the material basis data for subsequent micro-segment rebound curvature calculations. Subsequently, the extracted target installation trajectory centerline is discretized according to its geometric characteristics. To ensure that the discretization accuracy reflects the curvature changes in different regions, the system employs a hierarchical discretization strategy for different structural regions within the trajectory centerline. Specifically, for the R-angle region with the most dramatic curvature changes, a first discretization density is used, with at least 5 discretization points per millimeter to ensure sufficient curvature sampling accuracy. For the transition zone of a straight section where curvature changes are relatively gradual but still exhibits transitional characteristics, a second discretization density is used, with 2 to 4 discretization points per millimeter. For conventional straight sections with stable curvature and essentially maintaining straight-line characteristics, a third discretization density is used, with 0.5 to 1 discretization point per millimeter. By using hierarchical discretization, unnecessary computational loads can be avoided while ensuring computational accuracy, thus improving curvature compensation efficiency. After discretization, the entire target trajectory centerline is transformed into a large number of continuous micro-segments. For each micro-segment, springback compensation calculation is performed using its local radius of curvature and material springback characteristics. That is, the theoretical bending strain distribution of the sealing strip at that micro-segment is calculated, and then the residual strain of the material after extrusion or bending is solved by combining the material's elastic modulus, stress relaxation behavior, and thermal expansion characteristics. Then, the springback curvature of the micro-segment in the free state is calculated based on the solved residual strain, and this springback curvature is superimposed with the target installation curvature to obtain the target curvature of the micro-segment after springback compensation. The compensated target curvature can represent the spatial shape that the sealing strip should have before shaping, so that it fits the vehicle body surface perfectly after assembly and springback. Then, the target curvature after springback compensation calculated from all micro-segments is made continuous. Through curvature integral, three-dimensional curve fitting and smoothing algorithm, the compensation curvature of discrete micro-segments is reconstructed into a continuous and smooth spatial curve as the pre-forming target curve. This pre-forming target curve not only reflects the geometric shape of the vehicle body installation trajectory, but also integrates the material springback effect, neutral layer offset and regional curvature change law. It is an important basis for the optimization of extrusion die parameters and the design of heat-setting mold.

[0030] Furthermore, based on the aforementioned springback characteristic parameters, a target curvature springback compensation analysis is performed on each micro-segment to obtain the target curvature of each micro-segment after springback compensation, including:

[0031] Based on the radius of curvature of the micro-segment and the position of the neutral layer, the theoretical bending strain distribution of the sealing strip at the micro-segment is calculated; based on the theoretical bending strain distribution and the springback characteristic parameters, the residual strain after unloading is calculated using a material elasticity simulation model; based on the residual strain, the target curvature after springback compensation is calculated in reverse.

[0032] Optionally, to accurately obtain the natural bending shape of the sealing strip in its free state, for each discrete micro-segment, the strain distribution under bending state is calculated based on the radius of curvature of the corresponding micro-segment and the corresponding neutral layer position in the sealing strip cross-sectional model. Specifically, the sealing strip cross-section is discretized into multiple representative elements. Based on the distance of these elements relative to the neutral layer, the theoretical bending strain in the tensile and compressive zones is calculated using bending deformation theory. That is, the vertical distance of a point on the micro-segment relative to the neutral layer position is divided by the radius of curvature of the micro-segment to obtain the theoretical bending strain distribution of the entire cross-section at that micro-segment. Subsequently, based on the theoretical bending strain distribution and combined with the material's springback characteristics, the residual strain of the micro-segment after unloading is solved using a material elasticity simulation model. This material elasticity simulation model can employ the hyperelastic constitutive relations commonly used for rubber materials, such as the Mooney-Rivlin, Ogden, or Yeoh models. During the simulation, parameters such as the material's elastic modulus, yield strength, stress relaxation coefficient, and coefficient of thermal expansion are input into the model. Based on the nonlinear mechanical behavior of the sealing strip cross-section during loading (bending) and unloading, the residual strain value of the corresponding region is obtained. This residual strain characterizes the material's inherent recovery tendency after the external force disappears, serving as a crucial foundation for subsequent back-calculation of the compensation curvature. Finally, based on the obtained residual strain, the target curvature of the micro-segment after springback compensation is solved through curvature inversion. That is, the residual strain is considered as the driving force for the sealing strip to maintain bending in a free state. Using the micro-segment springback characteristic inversion relationship established by the material elasticity simulation model, and with the residual strain as input, the pre-forming compensation curvature required to achieve the target installation curvature is obtained through inverse calculation. In other words, the degree of pre-bending that the micro-segment should achieve before extrusion and shaping is determined. Through the above steps, an accurate springback compensation curvature can be calculated for each micro-segment. When the compensation curvatures formed by all micro-segments are integrated, the overall spatial morphology that the sealing strip should possess in the pre-forming stage can be generated, providing a precise basis for the extrusion die flow channel design and the manufacturing of the heat-setting die.

[0033] Furthermore, reconstructing a continuous spatial curve as a preform target curve also includes:

[0034] Using the obtained preform target curve as input, the target curvature springback compensation analysis is re-executed to obtain the target verification curvature; the curvature corresponding to the target verification curvature is compared with that of the preform target curve to obtain the curvature change; if the curvature change exceeds the deviation threshold, iterative verification is repeated until the curvature change is less than or equal to the deviation threshold, and the final preform target curve is output.

[0035] Optionally, to ensure that the generated preformed target curve can accurately offset the rebound effect of the sealing strip during extrusion, shaping, and assembly, the calculated preformed target curve is first used as input data, and a micro-segment level target curvature rebound compensation analysis is performed again. That is, the theoretical rebound curvature that the sealing strip may exhibit after unloading is calculated segment by segment according to the same steps described above, thereby obtaining a target verification curvature distribution corresponding to the preformed target curve, which is used to evaluate the compensation accuracy of the current preformed curve. Subsequently, the obtained target verification curvature is compared segment by segment with the curvature at the corresponding position of the preformed target curve, and the curvature difference between the two is calculated and recorded as the curvature change. These curvature changes are used to quantify the degree of deviation between the current preformed curve and the expected stress-free assembly state. Generally, for the R-angle region with drastic curvature changes, the curvature change is more sensitive and can reflect whether the compensation is in place; while in the straight segment, more attention is paid to convergence stability. Next, the curvature change is compared with a preset deviation threshold. This preset deviation threshold is pre-set by experts based on the material properties, structural form, and assembly precision requirements of the sealing strip. Preferably, the criterion is the percentage of the curvature change relative to the target curvature or the equivalent curvature radius change. Specifically, it is set to 2%–5% of the target curvature in the R-angle region, 1%–3% in the straight transition zone, and 0.5%–1% in the conventional straight section, or equivalently, a curvature radius change of no more than ±1.0–±3.0 mm. If the curvature change in any micro-segment exceeds the deviation threshold, it indicates that the current pre-formed target curve is insufficient to offset the actual springback behavior. The compensation curvature needs to be readjusted based on this change. In this case, the pre-formed target curve is updated, and the above springback compensation analysis steps are repeated to make the new pre-formed curve closer to the final stress-free bonding shape of the sealing strip. Through multiple iterations, when the curvature changes of all micro-segments do not exceed the deviation threshold, the pre-forming target curve is considered to have reached convergence. At this point, the final pre-forming target curve is output as a benchmark curve to guide the optimization of the extrusion die structure and the design of the heat-setting die. This iterative process ensures the accuracy of the pre-forming target curve and avoids problems of insufficient or excessive compensation, thereby ensuring that the sealing strip achieves an ideal geometric fit after assembly.

[0036] Based on the pre-forming target curve, an initial curvature target is set, and the pressure distribution flow channel parameters of the extrusion die are optimized. The external flow channel resistance of the extrusion die is configured using the optimized pressure distribution flow channel parameters to obtain a sealing strip semi-finished product with the initial curvature target.

[0037] In one embodiment, to ensure the sealing strip has an initial curvature consistent with the pre-formed target curve upon extrusion, the initial curvature values ​​required for the sealing strip at different positions are first calculated based on the obtained pre-formed target curve; that is, the spatial curvature distribution corresponding to the sealing strip in its free state. Subsequently, this target curvature information is converted into target flow velocity distributions in different regions of the extrusion die outlet section. Typically, in the pre-bent outer region, the sealing strip material should have a lower flow velocity to allow the outer material to contract relatively during extrusion; while in the pre-bent inner region, a higher flow velocity should be set to allow the inner material to be filled slightly more, thus creating a natural bending effect. This differential flow velocity distribution (higher inside, lower outside) is a crucial basis for the active pre-bending of the extrusion section. Next, a parametric flow channel model of the extrusion die is established. This model includes parameters such as flow channel height, length, convergence angle, and throttling structure width in different cross-sectional regions. These parameters determine the resistance distribution and pressure gradient of the material during extrusion. By using computational fluid dynamics (CFD) simulations, a mapping relationship is established between different flow channel geometric configurations and the actual flow velocity distribution at the outlet cross-section, enabling parameterized adjustment and accurate prediction in die design. Based on this mapping relationship, with the target flow velocity distribution as the optimization objective, optimization algorithms, such as genetic algorithms, gradient search, or multi-objective optimization methods, are employed to solve for a set of optimal flow channel geometric parameters that meet the target flow velocity requirements. This yields optimized combinations of flow channel height, throttling ratio, and convergence angle corresponding to different regions of the sealing strip cross-section, allowing the extrusion process to automatically form a pre-bent material distribution. These parameters are then applied to the extrusion die structure design, configuring a die structure with higher resistance in the outer flow channel and lower resistance in the inner flow channel. In this way, during actual extrusion, the material experiences uneven resistance as it flows within the die, resulting in differential flow within the cross-section. Consequently, the sealing strip exhibits an initial curvature consistent with the pre-formed target curve at the moment of die exit. Ultimately, through the optimized configuration of the pressure distribution and flow channel structure, the extruded sealing strip semi-finished product naturally has the required initial curvature without being bent by external force, providing an ideal basis for the subsequent heat setting process, and effectively reducing stress accumulation, wrinkles and warping problems in the extrusion section during assembly.

[0038] Furthermore, based on the pre-forming target curve, an initial arc target is set, and the pressure distribution flow channel parameters of the extrusion die are optimized, including:

[0039] The initial curvature target, combined with the sealing strip cross-sectional geometry and material rheological properties, is converted into a target velocity distribution at the extrusion die outlet section. The target velocity value corresponding to the outer region of the pre-bent product is less than the target velocity value corresponding to the inner region. A parameterized extrusion die flow channel model is established, where the flow channel geometric parameters include the flow channel height, length, and convergence angle corresponding to different regions of the extrusion section. Based on computational fluid dynamics simulation, a mapping relationship is established between the flow channel geometric parameters and the actual velocity distribution at the outlet section. Using the target velocity distribution as the optimization objective and the mapping relationship as constraints, an optimized set of flow channel geometric parameters is obtained by solving the extrusion die flow channel model using an optimization algorithm. Based on the optimized flow channel geometric parameters, the physical structure configuration of the extrusion die is determined, and pressure distribution parameters that result in low outer velocity and high inner velocity during the extrusion process are constructed to produce a pre-bent sealing strip semi-finished product that meets the initial curvature target.

[0040] Preferably, to ensure that the semi-finished sealing strip possesses the initial curvature required by the pre-forming target curve immediately after extrusion molding, the initial curvature targets at corresponding positions in the pre-forming target curve are first analyzed in conjunction with the cross-sectional geometry of the sealing strip and the rheological properties of the material. Based on the direction and curvature requirements of the pre-bending of the sealing strip, the cross-section is divided into an outer pre-bending region and an inner pre-bending region. Since the material flow rate during extrusion is related to the final forming bending trend, to ensure that the extrudate naturally bends inward, the material flow rate in the outer region needs to be designed to be lower, while the material flow rate in the inner region needs to be set to be higher, thereby creating a differential flow that promotes the material to bend in the preset direction. Therefore, based on the cross-sectional geometry, material viscoelastic parameters, and the initial curvature size, the initial curvature target is quantified into the target flow rate distribution in different regions of the outlet cross-section. Subsequently, a parameterized extrusion die flow channel model is established. This extrusion die flow channel model includes adjustable parameter definitions for the flow channel height, flow channel length, convergence angle, and throttling structure dimensions of each zone of the extrusion cross-section. By dividing the flow channel structure of the die into several independently adjustable regions, different regions can introduce corresponding flow resistance, thereby adjusting the local flow velocity at the outlet section. Then, based on computational fluid dynamics (CFD) methods, the above-mentioned parametric extrusion die flow channel model is simulated. Each flow channel parameter combination is adjusted sequentially, and the velocity, pressure, and shear field distribution of molten rubber flowing within the die are simulated. A set of mapping curves between flow channel geometric parameters and the actual flow velocity distribution at the outlet section is established. This mapping relationship reveals the influence of different flow channel structure adjustments on the change in outlet flow velocity, serving as the mathematical constraint basis for subsequent optimization solutions. Then, with the target flow velocity distribution as the optimization objective and the mapping relationship established by the CFD simulation as the constraint condition, an optimization algorithm is used based on the parametric extrusion die flow channel model to solve for the optimal flow channel structure combination that satisfies the target flow velocity. Taking a genetic algorithm as an example, the set of parameters to be optimized is first defined based on the parametric extrusion die flow channel model, including parameters such as flow channel height partition values, flow channel length ratios, and convergence angles. These parameters are then encoded as chromosome individuals in the genetic algorithm, with each individual representing a set of feasible die flow channel structure combinations. Next, an objective function is defined, which is the error function between the actual flow velocity and the target flow velocity at each sampling point of the outlet section. Specifically, a weighted mean square error (MSE) form can be used, with a higher weight given to the flow velocity error in the outer region of the pre-bending to ensure that the flow velocity on the outer side is reduced as much as possible to meet the pre-bending requirement. Furthermore, the established mapping relationship is used as the basis for calculating the fitness of the genetic algorithm. For each individual, its parameters are input into the mapping relationship to obtain the corresponding predicted flow velocity distribution, and the objective function value is calculated. Individuals with smaller errors have higher fitness.Next, the genetic algorithm performs iterative evolutionary operations, including selection, crossover, and mutation. Selection employs tournament selection or roulette wheel selection mechanisms, prioritizing individuals with high fitness for the next generation. Crossover involves combining selected parent individuals, for example, using a two-point crossover method to generate new flow channel parameter combinations, expanding the parameter space. Mutation slightly perturbs the parameters of some offspring individuals, such as randomly changing a flow channel height or convergence angle, enabling the algorithm to escape local optima and improve search capabilities. These operations generate a new generation of the population, and the iterations are repeated. As the number of iterations increases, the overall fitness of individuals in the population continuously improves, and the flow velocity error gradually decreases. When preset convergence conditions are met, such as the objective function error falling below a threshold or the number of iterations reaching its upper limit, the parameter set of the individual with the highest fitness is output, representing the optimal flow channel geometry parameters that satisfy the target flow velocity distribution requirements. Finally, based on the optimized flow channel parameters, the physical structure of the extrusion die is configured, including adjusting the flow channel height ratio inside the die, setting the throttling groove depth, optimizing the convergence angle, and adding resistance elements in different zones. This allows the die to achieve a pressure distribution and flow state with low flow velocity on the outer side and high flow velocity on the inner side during actual extrusion. Using the optimized extrusion die structure, pre-bent sealing strip semi-finished products with the target initial curvature can be stably extruded, thereby effectively reducing stress accumulation and wrinkling defects during subsequent heat setting and assembly processes.

[0041] Furthermore, the target velocity distribution converted to the extrusion die outlet cross-section includes:

[0042] Based on the curvature of the initial arc target, the strain energy density distribution at each point of the sealing strip cross-section under bending state is calculated; according to the strain energy density distribution and material rheological properties, the relative velocity difference at each point of the outlet cross-section required to achieve the corresponding energy state under the set extrusion traction rate is calculated; with the velocity in the neutral layer region of the extrusion cross-section as a reference, the relative velocity difference is superimposed to obtain the target velocity distribution.

[0043] Optionally, to ensure that the extruded sealing strip semi-finished product exhibits a predetermined curvature before being bent by external force, the strain energy density distribution of the sealing strip cross-section under bending conditions is first calculated based on the initial curvature target corresponding to the pre-forming target curve. Specifically, the sealing strip cross-section is discretized into multiple representative calculation points. Based on the magnitude of the curvature and the position of each point relative to the neutral layer, the bending strain in the tensile and compressive zones is calculated using the same method described above. Then, using the material's elastic modulus and hyperelastic constitutive models (such as the Mooney-Rivlin, Ogden, or Yeoh models), the calculated strain is converted into the strain energy density U at each point. These strain energy densities characterize the energy level required to be stored in each region of the material when the sealing strip reaches the target bending shape. After obtaining the strain energy density distribution, this distribution is combined with the material's rheological properties for back-analysis. Local velocity differences in the extrusion process of sealing strip materials cause variations in strain energy distribution across the cross-section. Therefore, under a set extrusion traction rate, the viscosity function and non-Newtonian rheological behavior of the material under different shear rates and temperatures are obtained through shear viscosity tests, flow index tests, and temperature dependence analysis. During extrusion, velocity differences in different regions of the die exit section lead to different forward propulsion amounts at the moment of die exit, resulting in geometric differences of relative packing on the inner side and relative stretching on the outer side within the cross-section. These geometric differences are converted into different tensile or compressive strains through the viscoelastic response of the material, manifesting as differences in strain energy density after molding. To describe this correspondence, a numerical model of the flow field during the extrusion process is constructed, inputting the local velocity difference into the material flow equation to simulate the stress distribution caused by differential flow near the die exit. The flow stress field is then coupled with the viscoelastic constitutive model of the material to calculate the residual strain on the inner and outer sides generated during the unloading process after leaving the die. By further converting the residual strain into strain energy density, a quantitative mapping relationship between the local velocity difference and the molding strain energy density is established.

[0044] After establishing the rheological response relationship, this relationship can be used to inversely deduce the local relative velocity difference required to achieve the target strain energy density. Specifically, the predetermined initial curvature target is transformed into the target strain energy density distribution of the sealing strip cross-section under bending conditions. This target distribution is then input into the aforementioned mapping relationship, and a numerical solution is used to search for the local velocity combination that makes the calculated strain energy density closest to the target value. Since this mapping relationship is continuous and monotonic, a higher local velocity will be deduced when the target region corresponds to a higher strain energy density; conversely, a lower local velocity will be obtained. Finally, using the velocity in the neutral layer region of the sealing strip cross-section as the reference velocity, the inversely derived relative velocity difference is superimposed on this reference velocity to obtain the complete target velocity distribution. This distribution is used to guide the structural optimization design of the extrusion die flow channel, ensuring that the extruded sealing strip semi-finished product naturally presents a pre-bent shape close to the target curvature at the moment of demolding, providing an accurate morphological basis for subsequent heat setting and assembly.

[0045] A heat-setting mold is set according to the pre-forming target curve. The semi-finished sealing strip with the initial curvature target is placed in the heat-setting mold for heating, pressure holding and cooling, so that the initial curvature is fixed and a pre-formed sealing strip is obtained.

[0046] In one embodiment, to ensure the initial curvature of the semi-finished sealing strip is stably maintained after extrusion molding, the acquired pre-forming target curve is first imported into the mold design system. Based on the three-dimensional spatial morphology of the pre-forming target curve, a corresponding heat-setting mold cavity profile is constructed. The mold cavity typically consists of two mold bodies, upper and lower, with its internal forming surface extending longitudinally along the sealing strip and strictly following the shape of the pre-forming target curve in space. To ensure the semi-finished sealing strip does not twist or shift during the molding process, the mating surface of the mold cavity is locally covered according to the geometric characteristics of the sealing strip cross-section. This includes corresponding support and positioning of the sealing lip, snap-fit ​​structure, and main adhesive cross-section, ensuring the semi-finished product maintains the correct posture within the mold cavity. Subsequently, the extruded semi-finished product with the initial curvature target is placed in the heat-setting mold cavity. After mold closing, the sealing strip inside the mold cavity is heated as a whole by a heating device on the mold side, such as an electric heating plate, an oil temperature circulation system, or a far-infrared heating element, to reach the target temperature range required for material softening and stress relaxation. This temperature is usually set according to the thermal reaction characteristics of EPDM or TPV materials, for example, within the range of 120℃-180℃, to ensure that the semi-finished product is in a state that can be reshaped under heat without damaging the material structure. After reaching the target temperature, appropriate mold closing pressure is maintained on the mold, so that the semi-finished sealing strip is tightly attached to the curved surface of the mold cavity, thereby restricting the outer side and holding the inner side in the designated position, allowing the pre-formed curvature to be stabilized and cured under thermal conditions. The duration of the pressure holding stage is set according to the degree of cross-linking of the material, heat conduction efficiency, and initial curvature size, to ensure that internal stress is fully released and the material chain segments are rearranged according to the mold shape. Finally, after the pressure holding is completed, the cooling process is initiated, and the mold temperature is reduced to near room temperature through cooling water channels or air cooling, so that the sealing strip completely fixes its bending shape in a cold state. After cooling, the sealing strip is removed, forming a pre-formed sealing strip with a smooth appearance, accurate curvature, and no springback deformation. This pre-formed sealing strip can naturally conform to the vehicle's curved surface during subsequent assembly, effectively eliminating defects such as warping, wrinkles, and assembly stress, thus improving assembly quality and sealing performance.

[0047] Furthermore, the preforming objectives include:

[0048] A sealing strip corner vulcanization mold is constructed, including a stop area for accommodating and limiting the semi-finished sealing strip. The surface of the stop area is a contoured surface that matches the outer contour of the pre-formed sealing strip. The curvature change of the contoured surface along the length of the sealing strip is consistent with the curvature change of the spatial arc of the pre-formed sealing strip. The pre-formed sealing strip is placed in the stop area of ​​the sealing strip corner vulcanization mold, and the mold is closed and vulcanized. During the mold closing process, the contoured surface fits against the outer contour surface of the pre-formed sealing strip, restricting springback deformation during vulcanization.

[0049] Preferably, to ensure that the pre-formed sealing strip maintains its established spatial curvature during the corner vulcanization process, firstly, based on the three-dimensional outer contour of the pre-formed sealing strip obtained after heat setting, its spatial geometry is imported into mold design software to construct the cavity structure of the corner vulcanization mold. A stop-recession area is then set within the mold to accommodate and position the semi-finished sealing strip. The surface of this stop-recession area adopts a contoured curved surface structure with the same height as the outer contour of the pre-formed sealing strip. That is, the curvature distribution of the stop-recession area along the length of the sealing strip strictly follows the target curvature curve of the pre-formed sealing strip, ensuring that the mold surface provides geometric constraints for contact with the sealing strip at every position. This allows the curvature changes in its three-dimensional space to precisely correspond to the spatial curvature of the pre-formed sealing strip. Subsequently, the pre-formed sealing strip with its initial curvature is placed in the corner vulcanization mold, ensuring that its outer contour surface completely conforms to the contoured curved surface of the stop-recession area. During placement, limiting blocks, locating pins, or undercut structures within the mold ensure that the sealing strip does not slide or rotate axially within the cavity, thus maintaining its precise position along its length. During mold closing, the closing force of the upper and lower molds causes the outer contour of the sealing strip to form a surface-to-surface contact with the contoured anti-reverse surface. Because the contoured surface provides complete geometric constraint on the shape of the sealing strip, even if the semi-finished sealing strip softens and exhibits thermal rebound during subsequent vulcanization heating, its deformation behavior is effectively limited by the contoured anti-reverse structure. At this time, stress relaxation and material flow within the sealing strip can only occur within the space allowed by the contoured surface, thus ensuring that the bending shape of the sealing strip does not shift or straighten. During the vulcanization process (typically at temperatures of 160°C–190°C), the material of the sealing strip undergoes a cross-linking reaction, and its internal structure gradually solidifies. The contoured anti-reverse structure continuously provides shape constraint throughout the vulcanization and pressure holding stage, ensuring that the final curvature of the sealing strip is stably maintained after curing. After vulcanization is complete and the mold is cooled to the set temperature, the removed sealing strip corner piece will have a spatial geometry that perfectly matches the pre-formed curvature, and will not exhibit springback deformation caused by heating. This contour-following anti-rebound design ensures that the sealing strip maintains its existing curvature during the corner vulcanization stage, avoiding the springback, twisting, and bending distortion problems common in traditional corner joining processes. This improves the fit and appearance consistency of the entire sealing strip during final assembly.

[0050] In summary, the embodiments of this application have at least the following technical effects:

[0051] First, a three-dimensional curve is extracted from the target installation area of ​​the vehicle body using 3D scanning, serving as the center line of the target installation trajectory. This curve represents the ideal fit of the sealing strip in a stress-free state. Next, based on this target installation trajectory center line, and considering the neutral layer position of the sealing strip cross-section and the material's springback characteristics, calculations and springback compensation are performed to generate a pre-formed target curve. Then, based on this pre-formed target curve, an initial curvature target is set, and the pressure distribution flow channel parameters of the extrusion die are optimized. The optimized pressure distribution flow channel parameters are used to configure the external flow channel resistance of the extrusion die, resulting in a semi-finished sealing strip with the initial curvature target. Finally, a heat-setting mold is set according to the pre-formed target curve. The semi-finished sealing strip with the initial curvature target is placed in the heat-setting mold for heating, pressure holding, and cooling, fixing the initial curvature and obtaining the pre-formed sealing strip. This invention solves the technical problems of appearance and sealing performance defects caused by the outer side lifting and separation, inner side extrusion wrinkling, and uneven assembly stress during the assembly and bending process when installing sealing strips on complex curved surfaces of the vehicle body, due to the straight state of the extrusion section. It achieves the technical effect of matching the sealing strip with the installation trajectory in a stress-free bonding state through pre-forming design based on the vehicle body space curve, eliminating wrinkles, lifting and rebound after assembly, stabilizing sealing performance, and improving assembly quality.

[0052] Example 2, based on the same inventive concept as the preforming optimization method for suppressing wrinkles in sealing strip assembly in the foregoing examples, such as... Figure 2 As shown, this application provides a preforming optimization system for suppressing wrinkles in sealing strip assembly. The system includes:

[0053] Curve Extraction Module 11: Extracts a three-dimensional spatial curve as the center line of the target installation trajectory by scanning the target installation area of ​​the vehicle body in three dimensions. The three-dimensional spatial curve represents the ideal fit space of the sealing strip under stress-free conditions. Springback Compensation Module 12: Calculates and compensates for springback based on the center line of the target installation trajectory, combined with the neutral layer position of the sealing strip cross-section and the material springback characteristics, to generate a pre-formed target curve. Parameter Optimization Module 13: Sets an initial curvature target based on the pre-formed target curve, optimizes the pressure distribution flow channel parameters of the extrusion die, and configures the external flow channel resistance of the extrusion die using the optimized pressure distribution flow channel parameters to obtain a semi-finished sealing strip with the initial curvature target. Semi-finished Product Processing Module 14: Sets a heat-setting mold based on the pre-formed target curve, places the semi-finished sealing strip with the initial curvature target in the heat-setting mold for heating, pressure holding, and cooling, so that the initial curvature is fixed, and obtains a pre-formed sealing strip.

[0054] Furthermore, the curve extraction module 11 is used to perform the following method:

[0055] The target installation area on the vehicle body is segmented according to the influence of assembly wrinkles, including an R-angle area, a straight transition area, and a regular straight section. Scanning paths and parameters are configured for the R-angle area, the straight transition area, and the regular straight section, with the scanning parameters including at least a scanning angle and a supplementary lighting angle. Based on the scanning parameters, scanning data for each target installation partition is obtained, and the scan data is fused and denoised to reconstruct a continuous installation surface model. The installation surface model is densely sectioned along a preset cross-sectional direction to obtain a series of cross-sectional contours. For each cross-sectional contour, the center point corresponding to the neutral layer position of the sealing strip installation is calculated. The center points corresponding to the series of cross-sectional contours are fitted and smoothed to generate a continuous three-dimensional spatial curve, which serves as the center line of the target installation trajectory.

[0056] Furthermore, the curve extraction module 11 is used to perform the following method:

[0057] Obtain the cross-sectional model of the sealing strip to be installed, which includes its snap-fit ​​structure, sealing lip structure, and material distribution information; calculate the theoretical neutral layer offset when bending deformation occurs under the curvature conditions corresponding to the current cross-sectional profile based on the structural and material properties of the cross-sectional profile; perform position compensation on the geometric center point of the cross-sectional profile based on the theoretical neutral layer offset to generate a compensated center point, wherein the calculation weight of the theoretical neutral layer offset is higher than that of the conventional straight section for the cross-sectional profile with R-angle.

[0058] Furthermore, the springback compensation module 12 is used to perform the following method:

[0059] Obtain the rebound characteristic parameters of the sealing strip material, including one or more of the following: elastic modulus, yield strength, coefficient of thermal expansion, and stress relaxation coefficient; discretize the center line of the target installation trajectory into continuous micro-segments; based on the rebound characteristic parameters, perform target curvature rebound compensation analysis on each micro-segment to obtain the target curvature after rebound compensation for each micro-segment; reconstruct a continuous spatial curve using the target curvature after rebound compensation calculated from all micro-segments, as the pre-formed target curve.

[0060] Furthermore, the springback compensation module 12 is used to perform the following method:

[0061] Based on the radius of curvature of the micro-segment and the position of the neutral layer, the theoretical bending strain distribution of the sealing strip at the micro-segment is calculated; based on the theoretical bending strain distribution and the springback characteristic parameters, the residual strain after unloading is calculated using a material elasticity simulation model; based on the residual strain, the target curvature after springback compensation is calculated in reverse.

[0062] Furthermore, the springback compensation module 12 is used to perform the following method:

[0063] Using the obtained preform target curve as input, the target curvature springback compensation analysis is re-executed to obtain the target verification curvature; the curvature corresponding to the target verification curvature is compared with that of the preform target curve to obtain the curvature change; if the curvature change exceeds the deviation threshold, iterative verification is repeated until the curvature change is less than or equal to the deviation threshold, and the final preform target curve is output.

[0064] Furthermore, the parameter optimization module 13 is used to perform the following method:

[0065] The initial curvature target, combined with the sealing strip cross-sectional geometry and material rheological properties, is converted into a target velocity distribution at the extrusion die outlet section. The target velocity value corresponding to the outer region of the pre-bent product is less than the target velocity value corresponding to the inner region. A parameterized extrusion die flow channel model is established, where the flow channel geometric parameters include the flow channel height, length, and convergence angle corresponding to different regions of the extrusion section. Based on computational fluid dynamics simulation, a mapping relationship is established between the flow channel geometric parameters and the actual velocity distribution at the outlet section. Using the target velocity distribution as the optimization objective and the mapping relationship as constraints, an optimized set of flow channel geometric parameters is obtained by solving the extrusion die flow channel model using an optimization algorithm. Based on the optimized flow channel geometric parameters, the physical structure configuration of the extrusion die is determined, and pressure distribution parameters that result in low outer velocity and high inner velocity during the extrusion process are constructed to produce a pre-bent sealing strip semi-finished product that meets the initial curvature target.

[0066] Furthermore, the parameter optimization module 13 is used to perform the following method:

[0067] Based on the curvature of the initial arc target, the strain energy density distribution at each point of the sealing strip cross-section under bending state is calculated; according to the strain energy density distribution and material rheological properties, the relative velocity difference at each point of the outlet cross-section required to achieve the corresponding energy state under the set extrusion traction rate is calculated; with the velocity in the neutral layer region of the extrusion cross-section as a reference, the relative velocity difference is superimposed to obtain the target velocity distribution.

[0068] Furthermore, the semi-finished product processing module 14 is used to perform the following methods:

[0069] A sealing strip corner vulcanization mold is constructed, including a stop area for accommodating and limiting the semi-finished sealing strip. The surface of the stop area is a contoured surface that matches the outer contour of the pre-formed sealing strip. The curvature change of the contoured surface along the length of the sealing strip is consistent with the curvature change of the spatial arc of the pre-formed sealing strip. The pre-formed sealing strip is placed in the stop area of ​​the sealing strip corner vulcanization mold, and the mold is closed and vulcanized. During the mold closing process, the contoured surface fits against the outer contour surface of the pre-formed sealing strip, restricting springback deformation during vulcanization.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A preforming optimization method for suppressing wrinkles in sealing strip assembly, characterized in that, include: By scanning the target installation area of ​​the vehicle body in three dimensions, the spatial three-dimensional curve is extracted as the center line of the target installation trajectory. The spatial three-dimensional curve represents the ideal fitting space state of the sealing strip under stress-free conditions. Based on the target installation trajectory centerline, combined with the neutral layer position of the sealing strip section and the material rebound characteristics, calculations and rebound compensation are performed to generate a pre-formed target curve; The step of calculating and compensating for rebound based on the center line of the target installation trajectory, combined with the position of the neutral layer of the sealing strip cross-section and the material rebound characteristics, to generate a pre-formed target curve includes: Obtain the resilience parameters of the sealing strip material, including one or more of the following: elastic modulus, yield strength, coefficient of thermal expansion, and stress relaxation coefficient; The center line of the target installation trajectory is discretized into continuous micro-segments; Based on the springback characteristic parameters, target curvature springback compensation analysis is performed on each micro-segment to obtain the target curvature of each micro-segment after springback compensation. Using the target curvature after springback compensation calculated from all micro-segments, a continuous spatial curve is reconstructed as the pre-forming target curve. Based on the pre-forming target curve, an initial curvature target is set, and the pressure distribution flow channel parameters of the extrusion die are optimized. The external flow channel resistance of the extrusion die is configured using the optimized pressure distribution flow channel parameters to obtain a sealing strip semi-finished product with the initial curvature target. A heat-setting mold is set according to the pre-forming target curve. The semi-finished sealing strip with the initial curvature target is placed in the heat-setting mold for heating, pressure holding and cooling, so that the initial curvature is fixed and a pre-formed sealing strip is obtained. By scanning the target installation area on the vehicle body in 3D, a 3D spatial curve is extracted as the center line of the target installation trajectory, including: The target installation area on the vehicle body is divided according to the influence of assembly wrinkles, including the R-angle area, the straight section transition area, and the regular straight section; The scanning path and scanning parameters are configured for the R-angle region, the straight section transition area, and the regular straight section, respectively. The scanning parameters include at least the scanning angle and the supplementary lighting angle. Based on the scanning parameters, the scanning data of each target installation partition is obtained, and the scanning data is fused and denoised to reconstruct a continuous installation surface model. The mounting surface model is densely sectioned along a preset cross-sectional direction to obtain a series of cross-sectional profiles; For each of the aforementioned cross-sectional profiles, calculate the center point corresponding to the location of the neutral layer where the sealing strip is installed; The center points corresponding to the series of cross-sectional contours are fitted and smoothed to generate a continuous three-dimensional spatial curve, which serves as the center line of the target installation trajectory. Calculate the center point corresponding to the location of the neutral layer where the sealing strip is installed, including: Obtain a cross-sectional model of the sealing strip to be installed, the cross-sectional model including its snap-fit ​​structure, sealing lip structure and material distribution information; Based on the structural and material properties of the cross-sectional profile, calculate the theoretical neutral layer offset when bending deformation occurs under the curvature conditions corresponding to the current cross-sectional profile; Based on the theoretical neutral layer offset, the geometric center point of the cross-sectional profile is compensated to generate a compensated center point. For the cross-sectional profile in the R-angle region, the calculation weight of the theoretical neutral layer offset is higher than that of the conventional straight segment. Based on the aforementioned springback characteristic parameters, a target curvature springback compensation analysis is performed on each micro-segment to obtain the target curvature of each micro-segment after springback compensation, including: Based on the radius of curvature of the micro-segment and the location of the neutral layer, the theoretical bending strain distribution of the sealing strip at the micro-segment is calculated; Based on the theoretical bending strain distribution and the springback characteristic parameters, the residual strain after unloading is calculated using a material elasticity simulation model. Based on the residual strain, the target curvature after springback compensation is calculated in reverse.

2. The preforming optimization method for suppressing wrinkles in sealing strip assembly according to claim 1, characterized in that, After obtaining the pre-formed sealing strip, the following is also included: Construct a sealing strip corner vulcanization mold, including a stop area for accommodating and limiting the pre-formed sealing strip, wherein the profile of the stop area is a contoured surface that matches the outer contour of the pre-formed sealing strip, wherein the curvature change of the contoured surface along the length direction of the sealing strip is consistent with the curvature change of the spatial arc of the pre-formed sealing strip. The pre-formed sealing strip is placed in the anti-reverse area of ​​the sealing strip corner vulcanization mold, and the mold is closed and vulcanized. During the mold closing process, the contoured surface fits into the outer contour surface of the pre-formed sealing strip, limiting the springback deformation that occurs during the vulcanization process.

3. The preforming optimization method for suppressing wrinkles in sealing strip assembly according to claim 1, characterized in that, Reconstructing a continuous spatial curve as the preform target curve also includes: Using the obtained preformed target curve as input, the target curvature springback compensation analysis is re-executed to obtain the target verification curvature. By comparing the target verification curvature with the curvature corresponding to the preformed target curve, the amount of curvature change is obtained; If the curvature change exceeds the deviation threshold, repeat the iterative verification until the curvature change is less than or equal to the deviation threshold, and then output the final preformed target curve.

4. The preforming optimization method for suppressing wrinkles in sealing strip assembly according to claim 1, characterized in that, Based on the preformed target curve, an initial arc target is set, and the pressure distribution flow channel parameters of the extrusion die are optimized, including: The initial arc target is combined with the cross-sectional geometry of the sealing strip and the rheological properties of the material to convert it into the target flow velocity distribution of the extrusion die outlet section; Establish a parameterized extrusion die flow channel model, wherein the flow channel geometric parameters include the flow channel height, length and convergence angle corresponding to different regions of the extrusion cross section; Based on computational fluid dynamics simulation, a mapping relationship between the geometric parameters of the flow channel and the actual velocity distribution at the outlet section is established; Using the target flow velocity distribution as the optimization objective and the mapping relationship as the constraint, a set of optimized flow channel geometric parameters are obtained by solving the optimization algorithm based on the extrusion die flow channel model. Based on the optimized flow channel geometry parameters, the physical structure configuration of the extrusion die is determined, and pressure distribution parameters that form a low outer flow velocity and a high inner flow velocity during the extrusion process are constructed to produce a pre-bent sealing strip semi-finished product that meets the initial curvature target.

5. The preforming optimization method for suppressing wrinkles in sealing strip assembly according to claim 4, characterized in that, The target velocity distribution converted to the extrusion die outlet cross section includes: Based on the curvature of the initial arc target, the strain energy density distribution at each point on the cross-section of the sealing strip under bending conditions is calculated. Based on the strain energy density distribution and material rheological properties, the relative velocity difference at each point of the outlet section required to achieve the corresponding energy state under the set extrusion traction rate is calculated. The target velocity distribution is obtained by superimposing the relative velocity difference on the flow velocity in the neutral layer region of the extrusion section as a reference.

6. A pre-forming optimization system for suppressing wrinkles in sealing strip assembly, characterized in that, A preforming optimization method for implementing the wrinkle suppression method for sealing strip assembly as described in any one of claims 1-5 includes: Curve extraction module: By scanning the target installation area of ​​the vehicle body in three dimensions, the module extracts a three-dimensional spatial curve as the center line of the target installation trajectory. The three-dimensional spatial curve represents the ideal fit space of the sealing strip under stress-free conditions. Springback compensation module: Based on the target installation trajectory centerline, combined with the neutral layer position of the sealing strip section and the material springback characteristics, it performs calculations and springback compensation to generate a pre-formed target curve; Parameter optimization module: Based on the pre-forming target curve, an initial curvature target is set, and the pressure distribution flow channel parameters of the extrusion die are optimized. The external flow channel resistance of the extrusion die is configured using the optimized pressure distribution flow channel parameters to obtain a semi-finished sealing strip with the initial curvature target. Semi-finished product processing module: A heat-setting mold is set according to the pre-forming target curve. The semi-finished sealing strip with the initial curvature target is placed in the heat-setting mold for heating, pressure holding and cooling, so that the initial curvature is fixed and a pre-formed sealing strip is obtained.

Images