Wheel cover outer plate closed drawing stamping process improvement method and automobile wheel cover outer plate

Abstract

The invention provides a wheel cover outer plate closed drawing stamping process improvement method and an automobile wheel cover outer plate, and relates to the technical field of automobile part manufacturing. Through a logic closed loop of'identifying a benchmark problem, optimizing local geometry to reduce risks, changing a feeding mode to realize full stretching, balancing integral feeding to promote uniform deformation, and obtaining a stable product through comprehensive application ', 'cracking prevention' and'rebound control 'treatment are realized. According to the method, the flow and deformation field of the plate in the forming process is reconstructed by adjusting the draft angle, the size of the plate, the parameters of the draw bead and other technological means, so that the material can obtain sufficient and uniform plastic stretching on the whole molded surface including the wheel brow and the two ends, the stress distribution state in the material is improved, and the material quality is improved. And the residual stress level is reduced, so that the cracking risk and the rebound tendency are relieved at the same time.

Description

Technical Field

[0001] This invention relates to the field of automotive parts manufacturing technology, and more specifically, to an improved method for the closed drawing and stamping process of wheel arch outer panels and an automotive wheel arch outer panel. Background Technology

[0002] As a typical deep-cavity structural component in automotive body panels, the wheel arch area typically has a much greater forming depth than other areas due to its styling characteristics (such as wheel arch design), generally reaching around 200mm. In the stamping process, these deep-cavity parts are prone to cracking during forming due to insufficient sheet metal flow, especially at the front and rear ends of the wheel arch area (where the radius of curvature is smaller).

[0003] To address the feeding challenges posed by deep cavities, existing technologies commonly employ an "open-end drawing" process with corresponding stamping dies. This process features the following die design characteristics: 1) The blank holder on the flange side is designed to be non-pressing or only slightly pressurizing, allowing the sheet metal in this area to flow quickly and freely into the die cavity during the initial drawing stage; 2) The draft angle of the sidewall in the flange side process supplement section is designed to be very small, typically 2°–5° in the Y direction, to reduce resistance to sheet metal flow and further promote rapid replenishment of the sheet metal into the deep cavity area; 3) Drawing ribs are arranged on the pressing surfaces in other areas of the die to exert a certain restraining force on the sheet metal flow.

[0004] However, in the "open drawing" process, the rapid feeding strategy adopted to solve the cracking problem in the deep cavity area of ​​the wheel arch is prone to insufficient stretching in the front and rear end areas, resulting in severe springback and dimensional deviation. Summary of the Invention

[0005] The purpose of this invention is to provide an improved method for the closed drawing and stamping process of the outer plate of the wheel cover, so as to alleviate the technical problems of severe springback and dimensional deviation in the prior art.

[0006] This invention provides an improved method for the closed drawing and stamping process of wheel arch outer plates, applicable to the drawing and forming of wheel arch outer plates where the forming depth on one side of the wheel arch is greater than that in other areas. The method specifically includes: The deep cavity forming area was determined, the initial drawing process scheme of the outer plate of the wheel cover was established, and the cracking risk and springback risk of one side of the wheel arch and the front and rear ends were analyzed. Based on the initial drawing process scheme, the draft angle of the process supplementary sidewall on one side of the wheel arch is adjusted to increase the draft angle of the sidewall on one side of the wheel arch. Increase the sheet metal unfolding size on one side of the wheel arch so that the pressure ring on one side of the wheel arch can hold the sheet metal in place throughout the entire forming stroke during drawing. The wheel arch side is changed from an open drawing process to a closed drawing process. In the forming area outside the wheel arch side, the drawbead parameters on the blank holder surface are reduced to decrease the constraint force of the drawbeads; The target wheel cover outer plate is obtained by drawing and forming based on the adjusted process parameters.

[0007] Further steps include identifying the deep cavity forming area, establishing the initial drawing process scheme for the outer plate of the wheel arch, and conducting forming analysis on the cracking and springback risks on one side and both ends of the wheel arch, including: The initial process design of the outer plate of the wheel arch is carried out according to the traditional open drawing process. The draft angle of the supplementary side wall of the wheel arch is set as the first draft angle. The drawing ribs on the blanking surface are arranged in a high-constraint manner. Through molding simulation or trial mold analysis, the analysis results of uneven feeding on one side of the wheel arch, cracking at both ends and severe springback were obtained under the traditional open-end drawing process. Based on this, a benchmark solution for process improvement was obtained.

[0008] Furthermore, based on the initial drawing process scheme, the process supplementary sidewall draft angle on one side of the wheel arch is adjusted to increase the draft angle of the sidewall on one side of the wheel arch; The draft angle of the side wall of the wheel arch is increased from the first draft angle to the second draft angle, and the second draft angle is greater than the first draft angle. The first draft angle is 2° to 5°, and the second draft angle is 50° to 60°.

[0009] Furthermore, increasing the sheet metal unfolding dimension on one side of the flange so that the blank holder on the flange side can hold the sheet metal in place throughout the entire forming stroke during drawing, and changing the flange side from an open drawing process to a closed drawing process, includes: Increase the unfolded size of the sheet metal along the outer edge of one side of the wheel arch, so that the sheet metal on one side of the wheel arch is completely pressed down by the pressure ring when the pressure ring is closed; The sheet metal on one side of the wheel arch is fed under controlled conditions only under the action of the blank holder force; The increase in sheet size is limited to the waste area, so that the length and width of the sheet remain unchanged, and the overall material utilization rate is not reduced.

[0010] Furthermore, in the step of reducing the drawbead parameters on the blank holder surface in the forming area other than the brow side to reduce the drawbead constraint force, the reduction adjustment of the drawbead parameters includes: Reduce the height of the drawbars located circumferentially on the outer plate of the wheel cover; Increase the radius of the corresponding drawbead punch.

[0011] Furthermore, before the step of drawing and forming the target wheel cover outer plate based on the adjusted process parameters, the following steps are also included: In the deep cavity location near one side of the wheel arch, the local shaping depth is reduced and the local fillet radius is increased to reduce the amount of molding deformation and stress concentration in the local area.

[0012] Furthermore, after the step of reducing the drawbead parameters on the blank holder surface in the forming area outside the brow side to reduce the drawbead constraint force, the process also includes: Based on the updated process parameters, a simulation analysis of the drawing and springback of the wheel arch outer plate was conducted to obtain the thickness distribution, stress distribution and springback amount on one side and both ends of the wheel arch. Judge the simulation analysis results to determine whether there is a risk of cracking or whether the end rebound exceeds the preset compensation threshold; If so, the draft angle of the side wall, the size of the sheet metal on the side of the wheel arch, and the height and fillet parameters of the draw beads in other positions should be adjusted again, and the drawing and springback simulation analysis should be repeated until the process requirements of no cracking and controllable springback are met.

[0013] Furthermore, the springback amount of the wheel arch side and the front and rear end sidewalls of the target wheel arch outer plate is less than or equal to 5mm.

[0014] Another objective of this invention is to provide an outer wheel arch panel for automobiles, which is manufactured using the provided method.

[0015] Beneficial effects: This invention provides a method for improving the closed-loop drawing and stamping process of wheel arch outer plates. Through a logical closed loop of "identifying baseline problems, optimizing local geometry to reduce risk, changing the feeding mode to achieve sufficient stretching, balancing overall feeding to promote uniform deformation, and comprehensively applying these principles to obtain a stable product," it achieves the management of "cracking prevention" and "springback control." In this invention, by adjusting the draft angle, sheet size, and drawbead parameters, the flow and deformation field of the sheet material during the forming process is reconstructed. This allows the material to achieve sufficient and uniform plastic stretching across the entire profile, including the wheel arch and both ends, improving the internal stress distribution and reducing residual stress levels, thereby simultaneously mitigating the risk of cracking and the tendency for springback.

[0016] The sidewall dimensions of the automotive wheel arch outer panel provided by this invention have small springback and small fluctuations, and the dimensional accuracy and long-term stability of the parts are reliably guaranteed. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 A schematic flowchart illustrating an improved closed drawing and stamping process for a wheel cover outer plate according to an embodiment of the present invention; Figure 2 This is a schematic diagram showing the location of the drawbars in the outer panel of an automobile wheel arch provided in an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0026] Combination Figure 1 This embodiment provides an improved method for the closed drawing and stamping process of wheel arch outer plates, applied to the drawing and forming process of wheel arch outer plates where the forming depth on one side of the wheel arch is greater than that in other areas. The method specifically includes the following steps: S1: Based on the product profile of the target wheel arch outer panel, determine that one side of the wheel arch is the deep cavity forming area, establish the initial drawing process scheme for the wheel arch outer panel, and conduct forming analysis on the cracking risk and springback risk of one side of the wheel arch and the front and rear ends.

[0027] S2: Based on the initial drawing process scheme, adjust the draft angle of the process supplementary sidewall on one side of the wheel arch to increase the draft angle of the sidewall on one side of the wheel arch, so as to reduce the sharpness of the surface on one side of the wheel arch and reduce the risk of cracking on one side of the wheel arch and the front and rear ends.

[0028] S3: Increase the sheet metal unfolding size on one side of the wheel arch so that the pressure ring on the wheel arch side can hold the sheet metal in place throughout the entire forming stroke during drawing. This changes the drawing process on the wheel arch side from an open drawing process to a closed drawing process, thereby limiting the sheet metal on the wheel arch side from flowing into the parting line too quickly and in excessive amounts.

[0029] S4: In other forming areas besides the wheel arch side, the drawbead parameters on the blank holder surface are weakened and adjusted to reduce the restraining force of the drawbeads in other positions. This guides the sheet metal from other areas to flow evenly into the deep cavity area of ​​the wheel arch and the front and rear end areas during the drawing process, in order to compensate for the material required for deep cavity forming.

[0030] S5: Based on the process parameters adjusted in steps S2 to S4, the wheel cover outer plate is stretched to ensure that the wheel arch side and both ends are fully stretched, and the stress distribution inside the plate tends to be uniform. This eliminates cracking, reduces sidewall springback, and improves the stability of the forming dimensions, ultimately obtaining the target wheel cover outer plate.

[0031] Specifically, in step S1, the geometric features of the target wheel arch outer plate are first identified, clarifying that the forming depth of its wheel arch area is significantly greater than other areas, defining it as a "deep cavity forming area" requiring special processing. Subsequently, an initial drawing process scheme conforming to traditional design thinking is established. This scheme typically simulates the "open drawing" mode in existing technologies, with typical features including: setting the draft angle of the sidewall supplementary process on the wheel arch side within a small range (e.g., approximately 2°–5° in the Y direction) to facilitate material feeding, and arranging drawing ribs with high resistance on the blank holder surface.

[0032] By using computer-aided engineering (CAE) molding simulation analysis or preliminary mold trials, the risks of material fracture (cracking) and post-molding shape springback in the wheel arch area and its front and rear ends under this design are predicted and assessed, obtaining specific risk distribution and quantitative data (such as predicted crack location and springback magnitude). This systematically correlates the product's geometric features (deep cavity) with potential process risks (cracking, springback), establishing an initial analysis based on traditional solutions and constructing a clear "problem baseline" or "control state" for simultaneous analysis of cracking and springback risks.

[0033] In step S2, the geometric reconstruction of the process supplement section on one side of the wheel arch is performed, increasing the draft angle of the sidewall in this area from a small range to a larger range. This transforms the sidewall area of ​​the wheel arch, where the product shape transitions to the process supplement surface, from a relatively steep and sharp shape to a more gentle and open shape.

[0034] The significant increase in draft angle alters the deformation path and stress state of the sheet metal flowing into this area. The gentler sidewalls reduce the bending and frictional resistance that the sheet metal must overcome as it flows through this region. Furthermore, it alleviates the sharp geometric features resembling a "bottleneck" that are easily formed at smaller draft angles, thereby reducing localized stress concentration at the wheel arch root and the front and rear end radius regions caused by flow obstruction and excessive thinning. This reduction in stress concentration directly corresponds to a decrease in the material's tendency to tear (i.e., cracking).

[0035] In step S3, during the process design phase, the unfolded dimensions of the sheet metal are increased along the outer side of the wheel arch contour. This increased dimension ensures that when the mold closes and the blank holder applies pressure, the sheet metal on the wheel arch side can be completely and stably held by the blank holder, preventing it from being prematurely pulled into the cavity of the mold. This transforms the forming process in this area from the traditional "open drawing" (where the blank holder applies little or no pressure) to "closed drawing" (where the blank holder effectively presses the material throughout the entire process).

[0036] Increasing the sheet metal size is a prerequisite for effective pressing and closed drawing. In closed drawing mode, the flow of sheet metal from the fender side is no longer unrestrained, but is controlled by the blank holder force throughout the entire drawing stroke. This controlled, gradual feeding method limits the sheet metal from "rushing too fast" and "climbing" onto the punch sidewall in the early stages of forming. Instead, the sheet metal is continuously and smoothly drawn into the cavity under the combined constraint of the blank holder and the die, thus undergoing more complete and uniform tensile plastic deformation. This achieves a key transformation in the fender side forming process while maintaining material utilization, providing a fundamental guarantee for sufficient stretching and uniform stress distribution of the sheet metal in this area, and fundamentally suppressing springback caused by insufficient stretching.

[0037] In step S4, to compensate for the potential reduction in overall feed volume caused by changing the wheel arch side to closed drawing, and to prevent new cracks from occurring in other areas or the wheel arch itself due to insufficient material supply, it is necessary to optimize the feeding conditions of other forming areas besides the wheel arch side (specifically, the flange area in the circumferential direction of the part in this embodiment). In this embodiment, by systematically adjusting the draw bead parameters, the feeding capacity of different areas of the die is balanced, ensuring that while the wheel arch side is fed under controlled conditions, the entire part still has sufficient and uniform material flow, thus synergistically preventing cracking and promoting the uniformity of overall deformation.

[0038] In step S5, steps S2, S3, and S4 are combined and executed. Based on the adjusted combination of process parameters, stamping is completed under these optimized conditions to obtain the final target wheel cover outer panel part. The elimination of cracking risk and the effective control of springback amount jointly improve the consistency, stability, and predictability of the part's forming dimensions.

[0039] In this embodiment, step S1 includes: S11: The initial process design of the outer plate of the wheel cover is carried out according to the traditional open drawing process. The draft angle of the supplementary side wall of the wheel arch is set as the first draft angle. The drawing ribs on the blanking surface are arranged in a high-constraint manner. S12: Through molding simulation or trial mold analysis, the analysis results of uneven feeding on one side of the wheel arch, cracking at both ends and severe springback are obtained under the traditional open-end drawing process, and the results are used as the benchmark scheme for process improvement.

[0040] Specifically, in step S11, a "comparison model" was constructed. This systematically set the key variables of the traditional process (small draft angle, strong draw bead force) to reproduce the standard working state of the existing technology in a computer or physical mold, thereby providing a "starting coordinate" with clear parameters and known state for all subsequent analysis and improvement.

[0041] In step S12, based on the initial scheme established in step S11, virtual or real loading tests are conducted using engineering analysis tools (Computer-Aided Engineering CAE simulation or actual mold prototyping). By simulating or executing the complete drawing process, key data are systematically collected and analyzed, specifically revealing the comprehensive problems under this traditional scheme: 1. Regarding sheet material flow, the feed rate is too fast on the flange side due to lack of constraint, while the feed rate is obstructed in other areas due to strong draw beads, resulting in "uneven feed"; 2. Regarding stress and strain, the R-corner areas at both ends may show a risk of "cracking" due to insufficient material replenishment or flow shear; 3. Regarding deformation and springback, significant "severe springback" (e.g., springback exceeding 5mm) is calculated or measured in the formed parts, especially the front and rear end sidewalls. These analysis results are fully recorded as "benchmark data" representing the current technological level. Through simulation or experimentation, the inherent contradiction between "cracking prevention" and "springback control" in traditional solutions is transformed from a qualitative description into concrete, visual, and quantifiable data (such as velocity field contour maps, thickness reduction rates, stress contour maps, and springback displacement vectors). This further clarifies the specific location, form, and severity of the problem.

[0042] In this embodiment, in step S2, the draft angle of the process supplementary sidewall on one side of the wheel arch is increased from the traditional first draft angle to a second draft angle, and the second draft angle is greater than the first draft angle; The first draft angle is approximately 2° to 5°, and the second draft angle is approximately 50° to 60°, in order to reduce the sharpness of the profile on one side of the wheel arch and alleviate stress concentration at the R-angle.

[0043] In this embodiment, the significant increase in the draft angle directly and substantially alters the geometric characteristics of this region and the deformation mechanics environment of the sheet metal. A smaller initial draft angle (2°–5°) creates a relatively sharp profile transition. When the sheet metal is drawn into this region during the drawing process, it undergoes severe bending and reverse bending deformation, and material accumulation and flow shearing are easily generated at the corner (R-angle), leading to a sharp increase in local stress (i.e., stress concentration). After increasing the angle to 50°–60°, the sidewall becomes extremely smooth, reducing the visual and mechanical "sharpness" of the profile on one side of the wheel arch. When the sheet metal flows through this smooth region, its bending deformation is alleviated, the flow path is smoother, and the local deformation resistance decreases. Secondly, the reduction in profile sharpness and the smoothing of the transition mitigate the material flow state at the root of the wheel arch and the critical R-angles at both ends, avoiding excessive local thinning of the material and stress peaks caused by geometrical abrupt changes. Effective control of the stress concentration level is crucial to preventing ductile fracture (i.e., stamping cracking) of the material.

[0044] In this embodiment, step S3 includes: S31: Increase the unfolded size of the sheet metal along the outer edge of one side of the wheel arch, so that the sheet metal on one side of the wheel arch is completely pressed by the pressure ring when the pressure ring is closed; S32: During the entire stroke from the closing of the blank holder to the end of the drawing process, the sheet metal on one side of the wheel arch is controlled to feed under the action of the blank holder force, so as to prevent the sheet metal from being completely drawn into the parting line and climbing to the side wall of the punch, thereby ensuring that the drawing on one side of the wheel arch is sufficient. S33: The increase in sheet size is limited to the scrap area, so that the length and width of the sheet remain unchanged and the overall material utilization rate is not reduced.

[0045] In this embodiment, step S31 specifically involves increasing the size of the blank in a specific area during the process design stage through digital expansion calculations, along the outer contour of the wheel arch structure. This ensures that when the upper die (or blank holder) descends and closes with the lower die blank holder, the sheet metal area corresponding to the wheel arch side is completely covered by the blank holder surface and subjected to stable positive pressure, thus establishing effective holding at the beginning of forming. In the traditional "open drawing" process, the sheet metal size on the wheel arch side is relatively small, with the aim of preventing the blank holder from "holding" it down or "holding it down too little," thereby achieving unconstrained feeding. In this embodiment, by increasing the size, the problem of "holding" it down is primarily solved. Only when the sheet metal is completely held down by the blank holder can sufficient frictional resistance and drawing resistance be generated, thereby changing the initial mechanical boundary conditions of the sheet metal in that area within the die.

[0046] In step S32, during the entire drawing stroke from the closing of the blank holder until the punch reaches its final position, the flow of the fender side sheet material is no longer free. Its flow rate and flow volume are mainly controlled by the blank holder force applied by the blank holder (through friction) and the resistance of the die opening to the drawing deformation of this part of the sheet material. This actively restricts the flow of the sheet material, preventing it from being rapidly and excessively "pulled" into the parting line and "climbing" upwards along the sidewall of the punch in the early stages of forming, similar to open-end drawing. This step, through blank holder force control, forces the sheet material to continuously withstand the drawing action from the die corners and sidewalls as it flows from the blank holder into the die, undergoing a longer and more gradual plastic stretching deformation. This controlled and continuous stretching is a necessary process to allow sufficient grain slippage within the material and generate uniform plastic strain (i.e., "sufficient drawing"), thus laying the foundation for reducing residual stress and springback.

[0047] In step 33, by precisely designing the increment within the area that is already considered process waste, it is equivalent to optimizing the shape of the waste area without changing the original billet procurement size and layout plan. This ensures that the measure of "increasing the sheet size to implement closed drawing" does not incur additional material costs.

[0048] In this embodiment, the reduction adjustment of the drawbead parameters in step S4 includes: S41: The height of the drawbeads located at positions A, B, and C on the outer plate of the wheel cover is reduced from the first height to the second height, which is less than the first height, in order to reduce the restraining force of the drawbeads; S42: Increase the fillet radius R of the corresponding drawbead punch from the first fillet radius to the second fillet radius to reduce the deformation resistance of the sheet at the drawbead and improve the sheet flowability; Specifically, in this embodiment, the first height is 6mm, the second height is 3mm, the first fillet radius is R3, and the second fillet radius is R6.

[0049] In step S41 of this embodiment, for the area outside the wheel arch side (such as...) Figure 2 The parameters of the drawbead structure on the blanking surface at positions A, B, C, etc. in the circumferential direction of product 2 are optimized. The core operation is to intentionally reduce the protrusion height of the drawbead from the original high first height (6mm) to a lower second height (3mm), thereby changing the geometric dimensions of the drawbead.

[0050] The mechanism of draw beads lies in the fact that before the sheet metal flows into the die cavity, it must first overcome the obstruction of the ribs, undergoing bending and reverse bending deformation, thereby consuming energy and generating resistance (i.e., restraining force) to the sheet metal flow. The height of the ribs is a key factor determining the magnitude of this resistance. According to the principles of material forming, the higher the rib height, the greater the curvature of the bending deformation that the sheet metal must undergo to overcome it, and the greater the bending moment and tensile force required, thus generating a stronger restraining force. Reducing the height from approximately 6 mm to approximately 3 mm significantly reduces the degree of bending deformation of the sheet metal, thereby directly reducing the overall restraining force of the draw beads on the sheet metal flow. This allows the sheet metal in the flange area, which is held down by the blank holder, to be pulled into the die cavity with less force, reducing the feeding resistance in non-deep cavity areas and creating conditions for promoting the flow of sheet metal from these areas inward.

[0051] In step S42, in conjunction with step S41, another key geometric parameter of the same drawbead—the punch fillet radius—is adjusted. This fillet radius is increased from a smaller first fillet radius (R3) to a larger second fillet radius (R6). This changes the curvature of the contact area between the top of the rib and the sheet metal, making the top of the rib smoother and flatter. This smooths the bending deformation path of the sheet metal at the rib, alleviates local strain concentration, and increases the contact area between the sheet metal and the rib, reducing contact pressure. This reduces the local deformation resistance and frictional resistance experienced by the sheet metal at the drawbead, further improving the flowability of the sheet metal when crossing the rib.

[0052] In this embodiment, before the step of drawing and forming the target wheel cover outer plate based on the adjusted process parameters, the method further includes: S6: At the deep cavity location adjacent to one side of the wheel arch, reduce the local shaping depth and increase the local fillet radius to reduce the amount of molding deformation and stress concentration in the local area; Specifically, in combination Figure 2 The shaping depth at position D is reduced from approximately 4mm to approximately 1.5mm, and the fillet radius at position D is increased to R8.

[0053] In this embodiment, within the framework of overall process optimization of the wheel arch outer panel, specific high-risk locations on the product surface (specifically, locations adjacent to the deep cavity region of the wheel arch in this embodiment) are addressed. Figure 2 Targeted geometric corrections were made at point D. The local shaping depth at point D was reduced from the initial deeper state (approximately 4mm) to a shallower state (approximately 1.5mm). At the same time, the local fillet radius at this point was increased to R8, thereby changing the surface geometry of the product at this location, effectively reducing the molding severity in this area, and dispersing and reducing stress peaks.

[0054] In this embodiment, after steps S2 to S4, the method further includes: S7: Based on the updated process parameters, perform drawing and springback simulation analysis on the outer plate of the wheel arch to obtain the thickness distribution, stress distribution and springback amount on one side and the front and rear ends of the wheel arch; S8: When the simulation analysis results still show a risk of cracking or the springback at the end exceeds the preset compensation threshold, the draft angle of the process supplementary sidewall on one side of the wheel arch, the sheet size on one side of the wheel arch, and the height and fillet parameters of the draw bead in other positions are adjusted again, and step S7 is repeated until the process requirements of no cracking and controllable springback are met.

[0055] In step S7, computer-aided engineering (CAE) simulation technology is used to construct an accurate digital twin model based on updated parameters (such as the increased draft angle, adjusted sheet metal profile, and reduced drawbead parameters), and to simulate the complete drawing process and subsequent unloading and springback. Through high-fidelity numerical calculations, the physical field data of key areas are systematically extracted and output, specifically including: sheet metal thickness distribution on one side of the wheel arch and at both ends, stress distribution during the forming process, and predicted springback after unloading, thus forming a comprehensive digital profile of the new solution's performance. This allows for early, rapid, and low-cost prediction of the new solution's actual effect on resolving the contradiction between "cracking" and "springback," and quantifies the effect, before expensive mold manufacturing and physical trial molding.

[0056] In step S8, the simulation analysis results are judged and identified. If the simulation analysis results in step S7 indicate that the updated solution still has a "cracking risk" (such as excessive thickness reduction rate or stress exceeding material strength) or "end springback exceeding the preset compensation threshold" (such as greater than 5mm), the system will not use it as the final solution. Instead, based on the specific failure mode (e.g., whether it is cracking in a certain place or excessive springback in a specific area), the relevant process parameters are adjusted again in a targeted manner. The adjustable parameters correspond to steps S2-S4, including: the draft angle of the process supplementary sidewall on one side of the wheel arch (adjusting its ability to mitigate stress concentration), the sheet metal size on one side of the wheel arch (adjusting its blanking effect and feed control strength), and the drawbead height and fillet parameters in other positions (adjusting the overall feed balance). After adjustment, the simulation analysis in step S7 is re-executed, forming an iterative cycle of "analysis-judgment-adjustment-reanalysis". Through iteration, the system can automatically or guide engineers to explore the parameter space and find the optimal or satisfactory solution set that can simultaneously achieve acceptable levels for both "cracking risk" and "springback", thus realizing multi-parameter collaborative optimization.

[0057] In this embodiment, the springback of the wheel arch side and the front and rear end sidewalls of the target wheel cover outer plate is less than or equal to 5mm.

[0058] In this embodiment, the springback of one side of the wheel arch and the front and rear end sidewalls must be less than or equal to the preset compensation value, which is no more than 5mm. Under this condition, the long-term stability of the wheel arch outer plate sidewall dimensions can be achieved.

[0059] The automotive wheel arch outer panel provided in this embodiment is manufactured using the improved closed drawing and stamping process method for wheel arch outer panels described above.

[0060] The sheet metal thickness distribution is more uniform, avoiding excessive thinning in certain areas; the residual stress level inside the part after forming is significantly reduced and more evenly distributed. It is this inherent superior condition shaped by specific processes that manifests externally as the excellent dimensional stability of the wheel arch outer plate. The springback in key areas such as one side of the wheel arch and the front and rear ends is effectively controlled at a low level (e.g., no more than 5mm), thereby ensuring high dimensional accuracy and good consistency of the parts, and solving the problems of assembly difficulties and low yield rates caused by excessive springback in traditional products.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the closed drawing and stamping process of the outer plate of a wheel cover, characterized in that, The method is applied to draw forming of wheel cover outer plate with one side of wheel arch forming depth greater than other areas, and the method comprises: determining deep cavity forming area, establishing initial draw forming process scheme of the outer plate of the wheel cover and performing forming analysis on cracking risk and springback risk of the one side of the wheel arch and front and rear end heads; based on the initial draw forming process scheme, adjusting process supplementary side wall draft angle of the one side of the wheel arch to increase side wall draft angle of the one side of the wheel arch; increasing sheet metal unfolding size of the one side of the wheel arch to enable draw bead ring of the one side of the wheel arch to press sheet metal in whole forming stroke in draw forming, and adjusting the one side of the wheel arch from open draw forming process to closed draw forming process; weakening draw bead parameters on the draw bead face in forming area other than the one side of the wheel arch to reduce restraint force of the draw bead; based on the adjusted process parameters, performing draw forming to obtain target wheel cover outer plate.

2. The method of claim 1, wherein, The step of determining deep cavity forming area, establishing initial draw forming process scheme of the outer plate of the wheel cover and performing forming analysis on cracking risk and springback risk of the one side of the wheel arch and front and rear end heads comprises: performing initial process design of the wheel cover outer plate according to traditional open draw forming process, process supplementary side wall draft angle of the one side of the wheel arch is set as first draft angle, and draw bead on the draw bead face is arranged in high restraint force mode; obtaining analysis results of uneven feeding of the one side of the wheel arch, cracking and serious springback of front and rear end heads in the traditional open draw forming process through forming simulation or trial forming analysis, and taking the analysis results as benchmark scheme for process improvement.

3. The method of claim 2, wherein, In the step of adjusting process supplementary side wall draft angle of the one side of the wheel arch based on the initial draw forming process scheme to increase side wall draft angle of the one side of the wheel arch, process supplementary side wall draft angle of the one side of the wheel arch is increased from the first draft angle to the second draft angle, and the second draft angle is greater than the first draft angle; wherein the first draft angle is 2°-5°, and the second draft angle is 50°-60°. The step of increasing sheet metal unfolding size of the one side of the wheel arch to enable draw bead ring of the one side of the wheel arch to press sheet metal in whole forming stroke in draw forming, and adjusting the one side of the wheel arch from open draw forming process to closed draw forming process comprises:

4. The method of claim 1, wherein, increasing sheet metal unfolding size in the direction of the outer edge of the one side of the wheel arch to enable sheet metal of the one side of the wheel arch to be completely pressed by the draw bead ring in the closed state of the draw bead ring; controlling the sheet metal of the one side of the wheel arch to be controlled feeding only under the action of the draw bead force; wherein the increase of the sheet metal size is limited in the waste area, the length and width of the sheet metal remain unchanged, and the overall material utilization rate remains unchanged. In the step of weakening draw bead parameters on the draw bead face in forming area other than the one side of the wheel arch to reduce restraint force of the draw bead, the weakening adjustment of the draw bead parameters comprises:

5. The method of claim 1, wherein, lowering the draw bead height arranged at the circumferential position of the wheel cover outer plate; increasing the round corner of the draw bead punch corresponding to the draw bead. Before the step of performing draw forming based on the adjusted process parameters to obtain target wheel cover outer plate, it further comprises:

6. The method of claim 1, wherein, reducing local modeling depth and increasing local round corner radius at the deep cavity position adjacent to the one side of the wheel arch to reduce forming deformation and stress concentration of the local area. ​ 7. The method according to any one of claims 1 to 6, characterized in that, The step of weakening the parameters of the drawbead on the blank holder surface to reduce the restraining force of the drawbead after the forming area outside the wheel arch side is further included: Based on the updated process parameters, the draw forming and springback simulation analysis of the wheel cover outer plate is performed to obtain the thickness distribution, stress distribution and springback amount of the wheel arch side and the front and rear end heads; Judging the simulation analysis results, whether there is a cracking risk or the end head springback amount exceeds the preset compensation threshold; If so, the wheel arch side process is supplemented with side wall draft angle, the wheel arch side plate size and other position drawbead height and round corner parameters are adjusted again, and the draw forming and springback simulation analysis is repeated until the process requirements of no cracking and controllable springback are met.

8. The method of claim 1, wherein, The springback amount of the wheel arch side and the front and rear end head side walls of the target wheel cover outer plate is less than or equal to 5mm.

9. An automobile wheelhouse outer panel characterized by comprising: The wheel cover outer plate is prepared by the method of any one of claims 1-8. The wheel cover outer plate is prepared by the method of any one of claims 1-8.

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