Rigidity evaluation method of stamping outer covering part

Abstract

The invention relates to a rigidity evaluation method of a part, in particular to a rigidity evaluation method of a stamping outer covering part, and aims to solve the problem that an effective method for evaluating the rigidity of the stamping outer covering part is lacked in an early engineering design stage in the prior art. In order to achieve the purpose, the stiffness evaluation method for the stamping outer covering part comprises the steps that a part generated in the engineering design stage is obtained, the influence of the part on the posture in the gravity state is simulated, and an area with large change is recognized; by applying external force to the part, the stress condition of the part is simulated, and the rigidity of the part is evaluated. Therefore, the stiffness evaluation method for the stamping outer covering part can be provided in the early-stage engineering design stage, stiffness simulation evaluation is carried out on an area with relatively weak local stiffness of the part, and improvement measures are verified.

Description

Technical Field

[0001] The invention relates to a method for evaluating the rigidity of a part, and in particular provides a method for evaluating the rigidity of a stamped outer covering part. Background Art

[0002] Automotive stamping parts are an important part of the automobile, and the manufacturing process level of automotive stamping parts indirectly affects the manufacturing cost and quality of the automobile. Stamping outer covering parts have more stringent requirements. Any tiny defect on the surface of stamping outer covering parts will cause diffuse reflection of light after painting and damage the appearance.

[0003] The poor rigidity of stamped outer covering parts is a common phenomenon in the stamping field of various automobile companies, especially the poor rigidity of shallowly drawn parts such as engine hood outer panels and door outer panels. In the actual production process, slight pressing by online operators and offline operators may cause plastic deformation of the parts themselves, thereby affecting the original dimensional state or A-surface state of the parts, and ultimately affecting the surface quality or single-piece size. Among them, A-surface refers to the "A" grade surface, that is, the exposed surface of the body outer covering.

[0004] At present, in the early stage of engineering design, there has been no effective method to evaluate the self-stiffness of stamped outer covering parts for their ability to resist deformation by external forces, that is, to evaluate the self-stiffness of stamped outer covering parts. Therefore, it is urgent to develop a method for evaluating the stiffness of stamped outer covering parts in the early stage of engineering design. Summary of the invention

[0005] The present invention aims to solve the above technical problem, that is, to solve the problem that the prior art lacks an effective method to evaluate the stiffness of the stamped outer cover itself in the early engineering design stage.

[0006] The present invention provides a method for evaluating the stiffness of a stamped outer cover, comprising the following steps:

[0007] Obtain the parts generated during the engineering design phase, simulate the effect of the parts on their posture under gravity, and identify areas with large changes;

[0008] Apply external force to the part, simulate the stress condition of the part, and evaluate the stiffness of the part.

[0009] In the preferred technical solution of the above-mentioned method for evaluating the stiffness of stamped outer cover, “obtaining the parts generated in the engineering design phase, simulating the influence of the parts on the posture under gravity, and identifying the areas with large changes” specifically includes:

[0010] placing said parts on a flat plate;

[0011] The part is repositioned under the influence of gravity, and the area with greater change is identified by the change in the previous posture of the part.

[0012] In the preferred technical solution of the above-mentioned method for evaluating the stiffness of a stamped outer cover, the step of "placing the part on a flat plate" is specifically:

[0013] In the springback process, the actual measurement module is selected, and the support tool is set to a plate, so that the part is placed on the plate.

[0014] In the preferred technical solution of the above-mentioned method for evaluating the stiffness of the stamped outer cover, the step of "applying external force to the part, simulating the force condition of the part, and evaluating the stiffness of the part" includes:

[0015] applying an external force to the part through a tool body;

[0016] The stiffness of the part is indirectly evaluated by the force applied to the tool body.

[0017] In the preferred technical solution of the above-mentioned method for evaluating the stiffness of the stamped outer cover, the step of "indirectly evaluating the stiffness of the part by the force applied to the tool body" is specifically:

[0018] Through the forming process, the upper and lower tool bodies are set as flat plates, and the parts are pressed. The tool force in the result evaluation is used to indirectly evaluate the stiffness of the parts by the force applied to the tool bodies within the same pressing stroke for different parts, and the areas of the parts with poor local stiffness are identified.

[0019] In the preferred technical solution of the above-mentioned method for evaluating the stiffness of the stamped outer cover, the step of "applying external force to the part, simulating the force condition of the part, and evaluating the stiffness of the part" includes:

[0020] applying an external force to the part through a tool body;

[0021] The stiffness of the component is indirectly evaluated by the equivalent strain of plastic mechanics.

[0022] In the preferred technical solution of the above-mentioned method for evaluating the stiffness of the stamped outer cover, the step of "indirectly evaluating the stiffness of the part by equivalent strain of plastic mechanics" is specifically:

[0023] Through the forming process, the upper and lower tool bodies are set as flat plates, and the part is pressed. Through the equivalent strain formula of plastic mechanics, the part is made to display the strain condition in the simulation result of the pressing process, so as to indirectly evaluate the stiffness of the part and identify the area of ​​the part with poor local stiffness.

[0024] In the preferred technical solution of the above-mentioned method for evaluating the stiffness of the stamped outer cover, the equivalent strain formula is:

[0025] ε eq=√(3 / 2*((ε1-ε2) 2 +(ε2-ε3) 2 +(ε3-ε1) 2 )),in,

[0026] ε eq is the equivalent strain,

[0027] ε1 is the first principal strain,

[0028] ε2 is the second principal strain,

[0029] ε3 is the third principal strain.

[0030] In the preferred technical solution of the above-mentioned method for evaluating the stiffness of stamped outer covering parts, the stiffness evaluation method further includes: identifying the area of ​​the part with poor local stiffness according to the stiffness evaluation method, taking measures to improve the stiffness of the area, and verifying the measures.

[0031] In the preferred technical solution of the above-mentioned method for evaluating the stiffness of the stamped outer cover, the step of "identifying the area of ​​the part with poor local stiffness according to the stiffness evaluation method, taking measures to improve the stiffness of the area with poor local stiffness, and verifying it" specifically includes:

[0032] regenerating the improved part according to the measures for increasing stiffness;

[0033] causing the improved part to execute the steps of the stiffness evaluation method to obtain a stiffness evaluation of the improved part;

[0034] When the stiffness of the improved part is higher than the stiffness of the part before the improvement, it is verified that the measure for improving the stiffness is effective.

[0035] In the case of adopting the above technical solution, the stiffness evaluation method of the stamped outer cover of the present invention obtains the parts generated in the engineering design stage, simulates the influence of the parts on the posture under the gravity state, and identifies the areas with large changes; by applying external force to the parts, the force conditions of the parts are simulated and the stiffness of the parts is evaluated. Therefore, the present invention can provide a stiffness evaluation method for stamped outer covers in the early engineering design stage, perform stiffness simulation evaluation on the areas with weak local rigidity of the parts and verify the improvement measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0037] Figure 1 is a schematic flow chart of the method for evaluating the stiffness of a stamped outer cover of the present invention;

[0038] Figure 2It is a schematic digital model drawing of the front door outer panel generated during the engineering design stage;

[0039] Figure 3 This is a schematic diagram of the operation when selecting the measurement module in the Autoform software;

[0040] Figure 4 It is a schematic operation diagram when adding a support body in the Autoform software;

[0041] Figure 5 yes Figure 2 Schematic diagram of the parts posture after the front door outer panel is rotated 90°;

[0042] Figure 6 yes Figure 5 A schematic diagram of the posture of the front door outer panel when the parts are in contact with the flat plate after the influence of gravity;

[0043] Figure 7 yes Figure 2 Schematic strain diagram of the center front door outer panel evaluated by the equivalent strain formula in Autoform software;

[0044] Figure 8 yes Figure 2 Schematic strain diagram of the center front door outer panel after the improvement measures were adopted, evaluated by the equivalent strain formula in the Autoform software;

[0045] Fig. 9 It is a schematic digital model drawing of the side outer panel generated during the engineering design stage;

[0046] Fig.10 yes Fig. 9 A schematic digital model of the taillight corner area of ​​the side panel after the improvement measures are adopted;

[0047] Fig.11 yes Fig. 9 Schematic strain diagram of the taillight corner area of ​​the side outer panel evaluated by the equivalent strain formula in Autoform software;

[0048] Fig.12 yes Fig.10 The schematic strain diagram of the taillight corner area of ​​the side outer panel after the improvement measures are evaluated by the equivalent strain formula in the Autoform software;

[0049] Fig.13 It is a schematic digital model diagram of the tailgate support buckle generated during the engineering design stage;

[0050] Fig.14 yes Fig.13 Schematic digital model of the tailgate support buckle after the improvement measures are adopted;

[0051] Fig.15 yes Fig.13 Schematic diagram of the tailgate support buckle when the pressing force is applied in the Z direction in the Autoform software;

[0052] Fig.16 yes Fig.14 Schematic diagram of the tailgate support buckle with improved measures when the pressing force is applied in the Z direction in the Autoform software;

[0053] Fig.17 yes Fig.15 A force state diagram of the tool body after the tailgate support buckle applies a Z-direction pressing force;

[0054] Fig.18 yes Fig.16 A force state diagram of the tool body after the tailgate support buckle applies a Z-direction pressing force;

[0055] Fig.19 yes Fig.13 Schematic diagram of the tailgate support buckle when the pressing force is applied in the Y direction in the Autoform software;

[0056] Fig. 20 yes Fig.14 Schematic diagram of the tailgate support buckle with improved measures when the pressing force is applied in the Y direction in the Autoform software;

[0057] Fig.21 yes Fig.19 A force state diagram of the tool body after the tailgate support buckle applies a Y-direction pressing force;

[0058] Fig. 22 yes Fig. 20 The force state diagram of the tool body after the tailgate support buckle applies Y-axis pressing force. DETAILED DESCRIPTION

[0059] The preferred embodiments of the present application are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present application and are not intended to limit the scope of protection of the present application. For example, although the various steps are described in a sequential order in the following embodiments, it is understood by those skilled in the art that in order to achieve the effect of the present embodiment, it is not necessary to perform in such an order between different steps, and they can be performed simultaneously (in parallel) or in a reversed order, and these simple changes are within the scope of protection of the present application.

[0060] Contemporary automobiles and modern mold design and manufacturing technologies have shown that the design and manufacturing of automobile cover molds cannot be separated from effective plate forming simulation software. The world's largest automobile groups, their body development and mold manufacturing must rely on one or several plate forming simulation software to improve their success rate and ensure the mold manufacturing cycle. International software mainly includes Dynaform of the American eta company, PAM series software of the French ESI Group, AutoForm of the German AutoForm Engineering Co., Ltd., and domestic software includes KMAS software of Jilin Golden Grid Mold Engineering Research Center, SheetForm of Beihang University, Vform of Huazhong University of Science and Technology, etc.

[0061] The stamped outer covering parts of a car usually include the engine hood outer panel, door outer panel, fender and side outer panel.

[0062] Figure 1 It is a schematic flow chart of the method for evaluating the stiffness of a stamped outer cover of the present invention. Figure 2 It is a schematic digital model drawing of the front door outer panel generated during the engineering design stage. Figure 3 This is a schematic diagram of the operation when selecting a measurement module in the Autoform software. Figure 4 This is a schematic diagram of the operation when adding a support body in the Autoform software. Figure 5 yes Figure 2 Schematic diagram of the parts posture after the front door outer panel is rotated 90°. Figure 6 yes Figure 5 Schematic diagram of the posture of the front door outer panel when the parts are in contact with the flat plate after the influence of gravity. Figure 7 yes Figure 2 Schematic strain diagram of the center front door outer panel evaluated using the equivalent strain formula in the Autoform software. Figure 8 yes Figure 2 Schematic strain diagram of the center front door outer panel after improvement measures were adopted, evaluated by the equivalent strain formula in the Autoform software.

[0063] like Figure 1 As shown, in order to solve the problem that the prior art lacks an effective method for evaluating the stiffness of the stamped outer cover itself in the early engineering design stage, the present invention provides a method for evaluating the stiffness of the stamped outer cover, which generally includes the following steps:

[0064] Step 100 , for example, the Autoform software can be used to obtain the parts generated in the engineering design phase, simulate the influence of the parts on the posture under the gravity state, and identify the areas with large changes;

[0065] Step 200, applying external force to the part, simulating the stress condition of the part, and evaluating the stiffness of the part.

[0066] Among them, parts refer to stamped outer covering parts.

[0067] In the case of adopting the above technical solution, the stiffness evaluation method of the stamped outer cover of the present invention obtains the parts generated in the engineering design stage, simulates the influence of the parts on the posture under the gravity state, and identifies the areas with large changes; by applying external force to the parts, the force conditions of the parts are simulated and the stiffness of the parts is evaluated. Therefore, the present invention can provide a stiffness evaluation method for stamped outer covers in the early engineering design stage, perform stiffness simulation evaluation on the areas with weak local rigidity of the parts and verify the improvement measures. In the preferred embodiment of the above-mentioned method for evaluating the stiffness of stamped outer covering parts, step 100 of "obtaining the parts generated in the engineering design phase, simulating the influence of the posture of the parts under gravity, and identifying the areas with large changes" specifically includes: placing the parts on a flat plate; repositioning the parts under the influence of gravity, and identifying the areas with large changes through the changes in the posture of the parts compared to the previous posture. More specifically, as Figure 3 As shown, select the real measurement module (Realmeasure) in the springback process of the Autoform software, such as Figure 4 As shown, set the Support tool to a flat plate, such as Figure 6 As shown, the part is placed on the plate. The part is placed on the plate and repositioned under the influence of gravity. Figure 6 ) and the previous posture (see Figure 5 ) changes, thus affecting the overall curvature distribution of the part. The changes in the weaker structural areas are more obvious. The surface depression function (Surface Low) can be used to identify the areas with larger changes. Figure 2 As shown in Figure 2, the area with larger changes is identified by the surface depression function. Figure 2 The circled area on the right side of the center front door outer panel.

[0068] In the preferred embodiment of the above-mentioned method for evaluating the stiffness of stamped outer covering parts, step 200, the step of "applying external force to the part, simulating the stress condition of the part, and evaluating the stiffness of the part" includes applying external force to the part through the tool body, and indirectly evaluating the stiffness of the part through the stress of the tool body. The step of "indirectly evaluating the stiffness of the part through the stress of the tool body" is specifically as follows: through the molding process of the software, the upper tool body and the lower tool body are both set as flat plates, the properties of the tool body are set to rigid (Rigid), the part is pressed, and the tool force in the result evaluation is used to indirectly evaluate the stiffness of the part by the force applied to the tool body within the same pressing stroke for different parts, and the area of ​​the part with poor local stiffness is identified. In the preferred embodiment of the above-mentioned method for evaluating the stiffness of stamped outer covering parts, step 200, the step of "applying external force to the part, simulating the stress condition of the part, and evaluating the stiffness of the part" includes: applying external force to the part through the tool body; indirectly evaluating the stiffness of the part through the equivalent strain of plastic mechanics. The step of "indirectly evaluating the stiffness of the part through the equivalent strain of plastic mechanics" is specifically: through the molding process of the software, the upper tool body and the lower tool body are both set to flat plates, the properties of the tool body are set to rigid (Rigid), the part is pressed, and the equivalent strain formula of plastic mechanics is edited in the software, and the strain condition of the part is displayed on the simulation result of the pressing process, and the stiffness of the part is indirectly evaluated, and the local area of ​​the part with poor stiffness is identified.

[0069] Among them, equivalent strain refers to the equal strain (or deformation) obtained by converting the three principal strains (or principal deformations) of anisotropic materials into the same strain (or deformation) under multiaxial stress state. The equivalent strain formula is:

[0070] ε eq =√(3 / 2*((ε1-ε2) 2 +(ε2-ε3) 2 +(ε3-ε1) 2 )) Formula 1

[0071] Among them, ε eq is the equivalent strain,

[0072] ε1 is the first principal strain,

[0073] ε2 is the second principal strain,

[0074] ε3 is the third principal strain.

[0075] See also Figure 6 , when the part is pressed, the thickness direction can be simplified to no strain, pure plane strain, that is, the plane principal and auxiliary strain. The above formula 1 can be simplified to:

[0076] ε eq =√(3 / 2*((ε1-ε2) 2 +(ε2) 2 +(ε1) 2 )) Formula 2

[0077] Edit the equivalent strain formula in the software as:

[0078] SQRT(3 / 2*SQR(MAJOR.M-MINOR.M)+SQR(MAJOR.M)+SQR(MINOR.M))

[0079] In a preferred embodiment of the above-mentioned method for evaluating the stiffness of stamped outer covering parts, the method further includes: step 300, identifying the area of ​​the part with poor local stiffness according to the stiffness evaluation method, taking measures to improve the stiffness of the area, and verifying the measures.

[0080] This embodiment can target different parts. Step 100 simulates the effect of gravity on the posture of the part on the flat plate under gravity, and then identifies the area with weak local stiffness through the surface depression function, identifies the area with large changes, and then applies external force to press the part through step 200. The stiffness of the part itself is evaluated by the force applied to the tool body or by the equivalent strain formula. By checking the force or strain diagram corresponding to the area with large changes identified in step 100 in the part, the area with poor local stiffness of the part is evaluated, the area with poor stiffness and prone to surface defects is identified, and the effectiveness of measures to improve stiffness is verified.

[0081] In the preferred embodiment of the above-mentioned method for evaluating the stiffness of the stamped outer cover, step 300, "identifying the area of ​​the part with poor local stiffness according to the stiffness evaluation method, taking measures to improve the stiffness of the area with poor local stiffness, and verifying" specifically includes:

[0082] Regenerate improved parts based on stiffness enhancement measures;

[0083] The step of causing the improved part to execute the stiffness evaluation method to obtain a stiffness evaluation of the improved part;

[0084] When the stiffness of the improved part is higher than the stiffness of the part before improvement, it is verified that the measures to increase the stiffness are effective.

[0085] Fig. 9 It is a schematic digital model drawing of the side outer panel generated during the engineering design stage. Fig.10 yes Fig. 9 Schematic digital simulation of the taillight corner area of ​​the side panel after improvement measures are adopted. Fig.11 yes Fig. 9 Schematic strain diagram of the taillight corner area of ​​the side panel evaluated using the equivalent strain formula in the Autoform software. Fig.12 yes Fig.10 The schematic strain diagram shown is of the taillight corner area of ​​the side outer panel after improvement measures evaluated by the equivalent strain formula in the Autoform software.

[0086] like Figure 2-8 As shown, the stiffness evaluation method of the stamped outer covering member of the present invention is applied to the front door outer panel. Figure 9-12As shown, the stiffness evaluation method of the stamped outer cover according to the present invention is applied to the corner area of ​​the taillight of the side outer panel.

[0087] Example 1

[0088] like Figure 3-8 As shown, execute step 100, such as Figure 3 As shown, select the real measurement module (Realmeasure) in the springback process of the Autoform software, such as Figure 4 As shown, set the Support tool to a flat plate and replace the front door outer panel (see Figure 2 ) on a flat plate and repositioned under the influence of gravity, through the front door outer panel (see Figure 6 ) and the previous posture (see Figure 5 ) changes, the surface depression function (Surface Low) can be used to identify Figure 2 The circled area on the right side of the center front door outer panel is the area with the largest changes.

[0089] Execute step 200, through the forming process of the software, set the upper and lower tool bodies to flat plates, set the properties of the tool bodies to rigid (Rigid), press the front door outer panel, edit the equivalent strain formula in the software: SQRT (3 / 2*SQR (MAJOR.M-MINOR.M) + SQR (MAJOR.M) + SQR (MINOR.M)), and display the strain condition based on the simulation results of the process of pressing the front door outer panel, such as Figure 7 As shown, the strain graph corresponding to the area with a larger change in step 100 is red, indicating that there is a high risk of concavity in the local area of ​​the front door outer panel, that is, the stiffness of this area is poor.

[0090] Execute step 300 to identify the Figure 2 The circled area on the right side of the center front door outer panel is the area with poor rigidity. Based on experience, measures to improve the rigidity of this area are taken. Specifically, Figure 2 The right circled area of ​​the middle front door outer panel is trimmed to increase by 1 mm. The improved front door outer panel is regenerated according to the measures to improve the rigidity, and the above steps 100 and 200 are performed on the improved front door outer panel. Figure 8 As shown in Figure 1, the strain diagram of the improved front door outer panel evaluated by the equivalent strain formula is obtained. Figure 8 As shown, the strain graph corresponding to the area with greater changes in step 100 is yellow, compared to Figure 7 The red color shown indicates that the improvement measures are effective.

[0091] according to Figure 2After the front door outer panel is manufactured into the front door outer panel product, it has been verified in practice that the front door outer panel product is Figure 2 The area circled on the right side of the middle front door outer panel has a concave surface. The improved front door outer panel is trimmed to increase the edge by 1mm in the area circled on the right side of the front door outer panel. The improved front door outer panel product is manufactured according to this improvement. Practice has verified that the improved front door outer panel product is Figure 2 The circled area on the right side of the center front door outer panel does not have the concave problem. Figure 2 The simulation of the front door outer panel and the improved front door outer panel, as well as the improved front door outer panel product performance were cyclically verified, which proved the reliability of the stiffness evaluation method of the present invention.

[0092] Example 2

[0093] like Figure 9-12 As shown, execute step 100, such as Figure 3 As shown, select the real measurement module (Realmeasure) in the springback process of the Autoform software, such as Figure 4 As shown, set the Support tool to a flat plate and replace the side panels (see Fig. 9 ) is placed on a flat plate and repositioned under the influence of gravity. The surface depression function (Surface Low) can be used to identify the change in the side panel's previous posture. Fig. 9 The circled area at the corner of the taillight on the center side outer panel is the area with the largest changes.

[0094] Execute step 200, through the forming process of the software, set the upper tool body and the lower tool body to be flat plates, set the tool body attribute to be rigid, press the side outer panel, edit the equivalent strain formula in the software: SQRT(3 / 2*SQR(MAJOR.M-MINOR.M)+SQR(MAJOR.M)+SQR(MINOR.M)), and display the strain condition according to the simulation results of the process of pressing the side outer panel, such as Fig.11 As shown, the strain graph corresponding to the area with a larger change in step 100 is black, indicating that there is a high risk of surface concavity in the local area of ​​the side panel outer panel, that is, the stiffness of this area is poor.

[0095] Execute step 300 to identify the Fig. 9 The area circled by the taillight corner of the center side panel is a relatively poor rigidity area. Based on experience, measures to improve the rigidity of this area are taken. Specifically, Fig. 9 The trimming of the area around the taillight corner of the center side panel is increased by 1mm (participate in Fig.10). According to the measures to improve the rigidity, the improved side outer panel is regenerated, and the above steps 100 and 200 are performed on the improved side outer panel. Fig.12 As shown in Figure 1, the strain diagram of the improved side panel evaluated by the equivalent strain formula is obtained. Fig.12 As shown, the black area of ​​the strain graph corresponding to the area with greater change in step 100 is compared to Fig.11 The black area shown has shrunk significantly, indicating that the improvement measures are effective.

[0096] according to Fig. 9 After the side panel is manufactured into the side panel product, the taillight of the side panel product has poor rigidity in the corner area of ​​the taillight due to the styling problem, resulting in obvious surface defects in the local area. The quality problem will be aggravated by the online tail transmission, employee packing, and post-process logistics transfer. It has been verified in practice that the local area of ​​the side panel product with poor rigidity is consistent with the area identified in step 100. Fig. 9 The area circled in the taillight corner of the side panel is highly consistent with the stiffness evaluation results. The improved side panel is the area circled in the taillight corner of the side panel, and the edge is trimmed and increased by 1mm. According to this improvement, the improved side panel product is manufactured. Practice has verified that the improved side panel taillight product is Fig. 9 The area circled in the taillight corner of the center side panel does not have a concave problem after normal extension. Fig. 9 The simulation of the side outer panel and the improved side outer panel, as well as the improved side outer panel product performance were cyclically verified, which proved the reliability of the stiffness evaluation method of the present invention.

[0097] The reliability of the stiffness evaluation method of the present invention was verified on the front outer panel and the side outer panel in Example 1 and Example 2, respectively, which proved the reliability of the stiffness evaluation method of the present invention.

[0098] Example 3

[0099] Fig.13 This is a schematic digital model of the tailgate support buckle generated during the engineering design stage. Fig.14 yes Fig.13 Schematic digital model of the tailgate support buckle after the improvement measures are adopted. Fig.15 yes Fig.13 Schematic diagram of the tailgate support buckle when the pressing force is applied in the Z direction in the Autoform software. Fig.16 yes Fig.14 Schematic diagram of the tailgate support buckle with improved measures when pressing force is applied in the Z direction in the Autoform software. Fig.17 yes Fig.15 The force state diagram of the tool body after the tailgate support buckle applies Z-direction pressing force. Fig.18 yes Fig.16 The force state diagram of the tool body after the tailgate support buckle applies Z-direction pressing force. Fig.19 yes Fig.13 Schematic diagram of the tailgate support buckle when the pressing force is applied in the Y direction in the Autoform software. Fig. 20 yes Fig.14 Schematic diagram of the tailgate support buckle with improved measures when pressing force is applied in the Y direction in the Autoform software. Fig.21 yes Fig.19 The force state diagram of the tool body after the tailgate support buckle applies Y-axis pressing force. Fig. 22 yes Fig. 20 The force state diagram of the tool body after the tailgate support buckle applies Y-axis pressing force.

[0100] like Figure 13-22 As shown in FIG. 1 , the stiffness evaluation method of the stamped outer cover according to the present invention is applied to the fender buckle. Fig.13 The fender buckle design shown is weak in rigidity and is prone to deformation during packaging. According to experience, adding reinforcement ribs at the fillet can effectively improve the structural strength, such as Fig.14 The improved fender buckle is shown, and the red arrow indicates the location of the reinforcement rib. However, how to quantitatively evaluate the effect of stiffness improvement?

[0101] Execute step 100 to identify Fig.13 The fender buckle has a larger deformation area at the rounded corner of the fender buckle. Fig.15 As shown, the tool body applies a Z-direction pressing force to the fender buckle to obtain Fig.17 The reaction force (Reaction Force) on the tool body shown is 320N. Continuing with step 200, as Fig.19 As shown, the tool body applies a Y-direction pressing force to the fender buckle and presses the root by 1 mm to obtain Fig.21 The reaction force (Reaction Force) on the tool body shown is 438N.

[0102] According to experience, adding reinforcement ribs at the fillet can effectively improve the structural strength, such as Fig.14 The improved fender buckle is shown in the figure, and the red arrow indicates the location of the reinforcement rib. Fig.16 As shown, the tool body applies a Z-direction pressing force to the improved fender buckle, and the Fig.18 The reaction force on the tool body shown is 360N. Fig. 20 As shown, the tool body applies a Y-direction pressing force to the fender buckle and presses the root by 1 mm to obtain Fig. 22The reaction force (Reaction Force) on the tool body shown is 943N.

[0103] like Fig.14 The improved fender buckle shown in the figure shows the contribution of the first rib to the Z-direction stiffness:

[0104] like Fig.14 As shown in the figure, the first rib is added, and the reaction force is Fig.17 The 320N increases to Fig.18 The first rib of the improved fender buckle contributes 15% more to the Z-direction stiffness.

[0105] like Fig.14 Evaluation of the contribution of adding a second rib to the overall stiffness is shown below:

[0106] like Fig.14 As shown in the figure, the first rib is added, and the reaction force is Fig.21 The 438N increases to Fig. 22 The Y-axis stiffness is increased by 1.15 times.

[0107] Although Examples 1-3 are described using the Autoform software architecture as an example, this is not restrictive. The stiffness evaluation method for stamped outer covers of the present invention can also be applied to software architectures with similar functions, such as the Dynaform software architecture, the PAM software architecture, the KMAS software architecture, the SheetForm software architecture, and the Vform software architecture.

[0108] The stiffness evaluation method of the stamped outer cover of the present invention provides some references and verification means for identifying the surface quality impact caused by the poor local rigidity of the parts, and can optimize the local rigidity of the door panel, improve the form and position of the fender buckle to avoid buckle deformation during the falling process, and improve the local concave problem caused by the poor local rigidity of the side panel. The present invention can simulate and verify the surface quality and deformation caused by the poor rigidity of a single stamped outer panel, and provide certain theoretical simulation guidance for the actual solution of the problem.

[0109] Those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims of the present application, any one of the claimed embodiments may be used in any combination.

[0110] It should be noted that although the detailed steps of the method of the present application are described in detail above, without departing from the basic principles of the present application, technical personnel in this field can combine, split and change the order of the above steps. The modified technical solution does not change the basic concept of the present application and therefore falls within the scope of protection of the present application.

[0111] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for evaluating the stiffness of a stamped outer cover, characterized in that: The following steps are involved: Obtain the parts generated during the engineering design phase, simulate the effect of the parts on their posture under gravity, and identify areas with large changes; Apply external force to the part, simulate the stress condition of the part, and evaluate the stiffness of the part.

2. The method for evaluating the stiffness of a stamped outer cover according to claim 1, characterized in that: "Obtaining the parts generated during the engineering design phase, simulating the impact of the parts on their posture under gravity, and identifying areas with large changes" specifically includes: placing said parts on a flat plate; The part is repositioned under the influence of gravity, and the area with greater change is identified by the change in the previous posture of the part.

3. The method for evaluating the stiffness of a stamped outer cover according to claim 2, characterized in that: The steps of "placing the part on the plate" are as follows: In the springback process, the actual measurement module is selected, and the support tool is set to a plate, so that the part is placed on the plate.

4. The method for evaluating the stiffness of a stamped outer cover according to claim 1, characterized in that: The step of "applying external force to the part, simulating the stress condition of the part, and evaluating the stiffness of the part" includes: applying an external force to the part through a tool body; The stiffness of the part is indirectly evaluated by the force applied to the tool body.

5. The method for evaluating the stiffness of a stamped outer cover according to claim 4, characterized in that: The specific steps of "indirectly evaluating the stiffness of the part by the force applied to the tool body" are: Through the forming process, the upper and lower tool bodies are set as flat plates, and the parts are pressed. The tool force in the result evaluation is used to indirectly evaluate the stiffness of the parts by the force applied to the tool bodies within the same pressing stroke for different parts, and the areas of the parts with poor local stiffness are identified.

6. The method for evaluating the stiffness of a stamped outer cover according to claim 1, characterized in that: The step of "applying external force to the part, simulating the stress condition of the part, and evaluating the stiffness of the part" includes: applying an external force to the part through a tool body; The stiffness of the component is indirectly evaluated by the equivalent strain of plastic mechanics.

7. The method for evaluating the rigidity of a stamped outer cover according to claim 6, characterized in that: The specific steps of "indirectly evaluating the stiffness of the part by equivalent strain of plastic mechanics" are: Through the forming process, the upper and lower tool bodies are set as flat plates, and the part is pressed. Through the equivalent strain formula of plastic mechanics, the part is made to display the strain condition in the simulation result of the pressing process, so as to indirectly evaluate the stiffness of the part and identify the area of ​​the part with poor local stiffness.

8. The method for evaluating the rigidity of a stamped outer cover according to claim 7, characterized in that: The equivalent strain formula is: e eq =√(3 / 2*((ε1-ε2) 2 +(ε2-ε3) 2 +(ε3-ε1) 2 )), among them, ε eq is the equivalent strain, ε1 is the first principal strain, ε2 is the second principal strain, ε3 is the third principal strain.

9. The method for evaluating the stiffness of a stamped outer cover according to any one of claims 1 to 8, characterized in that: The stiffness evaluation method further includes: identifying a region of the part with poor local stiffness according to the stiffness evaluation method, taking measures to improve the stiffness of the region, and performing verification.

10. The method for evaluating the rigidity of a stamped outer cover according to claim 9, characterized in that: The step of "identifying the area of ​​the part with poor local stiffness according to the stiffness evaluation method, taking measures to improve the stiffness of the area with poor local stiffness, and verifying" specifically includes: regenerating the improved part according to the measures for increasing stiffness; Allowing the improved part to execute the steps of the stiffness evaluation method to obtain a stiffness evaluation of the improved part; When the stiffness of the improved part is higher than the stiffness of the part before the improvement, it is verified that the measure for improving the stiffness is effective.

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