A method of forming a multi-panel automobile panel

Abstract

The application discloses a kind of mould forming manufacturing methods of multi-splicing automobile covering, comprising the following steps: main trend analysis, dispersed slip drawbead construction, reverse material feeding compensation, gradual transition zone, unequal gap die surface compensation, pressure equipment deflection compensation.The application changes material feeding control mode by dispersed slip drawbead construction, changes material feeding control to uniform change material feeding mode, thereby solve the problem that the slip of lightweight material is difficult to control, provide key technical support for the multi-splicing mould forming of lightweight material;Reverse material feeding compensation makes the material feeding form of different material feeding amounts of complex shape controllable to the joint slip amount of multi-splicing material, thereby ensure the accurate control of slip amount, solve the problem of serious deformation of multi-thickness and multi-material splicing, and cannot be formed with high quality;Eliminate the serious problem that mold manufacturing cannot be used with high precision due to the change of machine difference and equipment difference when online production.

Description

Technical Field

[0001] This invention relates to the field of automotive body panel mold manufacturing technology, and in particular to a mold forming manufacturing method for multi-joint automotive body panels. Background Technology

[0002] To enhance vehicle strength, reduce costs and weight, and save energy, splicing sheet metal has become an important method in the manufacturing process of automotive parts. It is widely used in load-bearing components such as beams and doors. The high strength, weight reduction, and low cost advantages of spliced ​​sheet metal have gained widespread market trust.

[0003] In existing technologies, the manufacturing of spliced ​​sheet metal automotive parts mainly relies on traditional forming analysis methods combined with multiple adjustments by fitters to create molds. While this is barely feasible for traditional sheet metal, the mold manufacturing costs are high, the cycle is long, and there are many uncertainties, affecting the overall quality. This is especially true for splicing multiple sheet metals of varying thicknesses or lightweight sheet metals, such as aluminum alloys, where forming is almost impossible. Therefore, the high forming difficulty, high mold manufacturing costs, low quality, and large variations in results from different pressure equipment severely restrict the application of multi-splicing technology. The main challenges lie not only in the different material thicknesses at the joints, leading to poor overall part quality due to improper material slippage control, and the difficulty in controlling slippage when splicing lightweight materials or different materials, but also in the influence of production equipment. After mold manufacturing, variations occur during online production, and equipment differences have a significant impact, making it impossible to use the mold with high precision. This poses a significant challenge to the application of multi-splicing technology. Summary of the Invention

[0004] To address the shortcomings in the aforementioned background technology, this invention proposes a mold forming manufacturing method for multi-joint automotive body panels, which solves the technical problem that existing technologies cannot guarantee the forming quality after welding plates of different thicknesses or materials.

[0005] The technical solution of this application is as follows: A method for manufacturing a multi-joint automotive body panel using mold forming, comprising the following steps: Step 1: Main trend analysis; This mainly involves analyzing the overall shape of the parts and the direction of the splicing panels, using the splicing direction line as the main direction line, and taking the highest point of the parts as the center to explore the trend outline. Step 2: Constructing the dispersed slip drawbar; Step 3, Reverse material feeding compensation; Reverse material feeding compensation is mainly for the material feeding setting in the splicing joint direction. It optimizes the shape of both sides of the joint to ensure that the material feeding area is outside the joint, so as to ensure that the joint area does not deform or deforms less. Step 4, Gradual Transition Zone; The purpose of the gradual transition zone is to create a gap at the joint position to prevent the thicker plate area from sliding into the thinner plate area at the joint position and causing cracks or scratches. However, if the transition zone is too large, it is easy to cause insufficient forming or product defects. Therefore, the setting of the transition zone should be adjusted according to the material thickness and shape. Step 5: Unequal gap die surface compensation; Unequal gap die surface compensation is mainly for the punch and vertical surface. The overall die gap is controlled according to the shape of the part to achieve a dynamic full fit under the deformation of the die under pressure, so as to ensure the forming quality of the part. The compensation is divided into two types: center surface compensation and vertical surface compensation. Step 6: Pressure Equipment Deflection Compensation; Pressure equipment deflection compensation involves establishing a machine tool deflection cloud map based on the difference between the deflection of the pressure equipment workbench on the manufacturing production line and the deflection of the pressure equipment at the mold manufacturing stage, forming a deflection parameter module, and performing corresponding deflection compensation on the part punch, so that no machine error variation occurs after the mold enters the production line, ensuring product quality.

[0006] Preferably, the specific method of step 1 includes the following steps: Step 1.1: Construct splicing direction array lines; extract the splicing line of the part as the baseline, and then make a parallel line array with a spacing of 100mm. At the same time, construct lines along the vertical direction of the array line at 100mm intervals until the entire part area is covered, forming the splicing direction array lines. Step 1.2: Using the highest point of the part as the center, construct a cone or trapezoidal body according to the shape of the part as an envelope to cover the entire part. If the part shape is similar to a basin, construct a cone; if the part shape is similar to a box, construct a trapezoid. Move the envelope down to the top 15-25mm away from the highest point. Step 1.3: Construct a plane with the splicing direction array lines to form an intersecting surface with the envelope. The intersection line is used as a trend line. Break the intersection line with the splicing direction array lines to form line segments. Translate each line segment to the edge of the part outline. Connect the middle part of the adjacent line segments with the splicing direction array lines to form the main trend outline of the part, thus completing the main trend analysis.

[0007] Preferably, the specific method of step 2 includes: taking the conventional drawbead arrangement position of the part as a reference position, optimizing the rounding with the main trend contour line as the main direction, and smoothly transitioning the drawbead to form a drawbead whose trend is similar to the main trend contour line; the drawbead can be designed as a square rib or a round rib according to the characteristics of the part, but the width of the drawbead needs to be consistent and cannot be a gradient drawbead; when the drawbead locking material is insufficient, a drawbead array is made to generate multiple drawbeads, but the width of the drawbead needs to be consistent except at the end, and the spacing between the drawbeads is between 25-35mm.

[0008] Preferably, the anti-material compensation method in step 3 includes method 3.1, dual-material splicing, in which a return arc compensation surface is constructed outside the part area on both sides of the splice along the large deformation trend of the main body of the part. The anti-arc surface is optimized according to the shape of the part and the position of the drawbead is adjusted to form a force trend area opposite to the direction of the part. By expanding the drawbead array, the locking force of different areas is adjusted to ensure that the splice does not deform or the deformation is translated in the same direction. However, the overall translation amount does not exceed 3mm, and the translation can only move in the direction of thicker material. This process requires batch compensation optimization and drawbead position adjustment. The CAE result is selected as the process model after CAE analysis to select the optimal effect.

[0009] Preferably, the anti-material feeding compensation method in step 3 also includes method 3.2. For multi-material splicing, in addition to using the above method, it is also necessary to select a waste area in the middle splicing material area to construct a small convex and concave structure. The shape of this structure is used to stabilize the material feeding, thereby preventing irregularity in the material feeding. The construction mode is to find a waste area near the middle material feeding area that exceeds 3mm and set a convex and concave shape. Its height is set to be preferably pulled back to the original position according to CAE analysis. The offset is controlled within 3mm by pulling back along the shaping point.

[0010] Preferably, the anti-feed compensation method in step 3 further includes: Method 3.3, for parts with complex shape changes and difficult anti-feed pullback, by optimizing the part shape, smoothing the part shape without affecting the part strength and function, and performing deformation optimization according to molding requirements and part matching requirements.

[0011] Preferably, the transition area setting method in step 4 is as follows: a 3mm gap is set from the side with greater thickness to the side with less thickness. The gap in this area is set according to the thickness of the thick material. A gradual gap transition is made from the outside of the 3mm area to the direction of the thin material. The width of the transition area is calculated according to the following formula: the width of the transition area D = (thick material thickness - thin material thickness) * 2.5.

[0012] Preferably, the center surface compensation method in step 5 is as follows: Step 5.1, Center Surface Compensation; Taking the highest point of the part as the center and the middle plane as the area, a gradual bulge is made on the shape of the punch. The center height of the gradual bulge is the maximum bulge height, which is calculated according to the following formula: Maximum bulge height H = material thickness * 0.3 * longest diameter of the central planar area / 500.

[0013] Preferably, the facade compensation method in step 5 is as follows: Step 5.2, facade compensation; facade compensation is performed when the facade angle is above 45 degrees, and the method is to gradually expand the facade area from the bottom of the facade upwards. The expansion amount is the distance from the top of the facade, which is the maximum expansion amount. The maximum expansion amount is calculated as follows: maximum expansion amount L = facade angle % * material thickness * 0.17.

[0014] Preferably, the pressure equipment deflection compensation in step 6 is divided into two stages: process mold surface compensation and debugging simulation compensation, as follows: Step 6.1, Process Die Surface Compensation; This mainly involves calculating the approximate deflection based on the structure of the upper and lower worktables of the equipment and the dimensions of the die. The deflection Ymax1 of the pressure equipment worktable in the manufacturing production line and the deflection Ymax2 of the pressure equipment in the die manufacturing stage are used. Based on the ratio of the deflections of the two pieces of equipment, the maximum height of the die punch's rise or fall is determined. Then, the punch is gradually raised or lowered as a whole, with the center point of the rise or fall being the center point of the die. The selection of the rise or fall and the method for calculating the height are as follows: If Ymax1 > Ymax2, the price rises; conversely, if Ymax1 is lower than Ymax2, the price falls. Height h = Ymax1 / Ymax2 * mold length / 1000 * 0.2 + Ymax1 / Ymax2 * 0.1; Step 6.2: Debugging and simulation compensation. If the punch bulges during debugging, add a shim with a mold length of 30% and a thickness of h in the middle of the punch; if the punch sags, add shims with a width of 15% of the mold length and a thickness of h to both ends of the mold along its length.

[0015] Compared with the prior art, the technical solution of the present invention has the following technical effects: 1. This invention, through the construction of dispersed slip drawbeads, changes the material feeding control mode, transforming it into a uniformly varied feeding method. This solves the problem of difficult slip control in lightweight materials, providing key technical support for the multi-joint mold forming of lightweight materials. 2. Reverse material feeding compensation enables the controllability of the slippage of the seams between multiple splicing materials in complex shapes with different material feeding patterns, thereby ensuring precise control of the slippage. This solves the problem of severe deformation and inability to form high-quality molding when splicing multiple thick materials and multiple materials. It forms a transferable model to innovate the method of multi-splicing molding and realizes high-quality molding of multi-material splicing.

[0016] 3. Unequal gap die surface compensation and pressure equipment deflection compensation solve the uncertainty of results caused by material thinning and die pressure deformation under dynamic conditions. At the same time, deflection compensation solves the problem of re-adjustment or even failure to form caused by differences in pressure equipment. It allows for a calculable early compensation mode for the differences between the pressure equipment in the manufacturing production line and the pressure equipment in the die manufacturing stage. This eliminates the serious problem of machine difference changes occurring after die manufacturing and when the die is put into production, and the serious problem of the die being unable to be used with high precision due to excessive equipment differences. Attached Figure Description

[0017] To more clearly illustrate 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.

[0018] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0019] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] To address the technical problems existing in the background art, the technical solution of this invention innovatively introduces a pressure equipment deflection analysis database, adds deflection compensation, implements batch forming mechanical flow line analysis and manufacturing experiments, adds a progressive transition region and forming optimization, and through continuous research and improvement, develops a mold forming manufacturing method for multi-joint automotive body panels. This technology solves the problem of multi-joint mold forming for splicing two or more material thicknesses and new lightweight materials such as aluminum alloys and magnesium alloys by constructing dispersed slip draw beads, reverse material feeding compensation, progressive transition regions, unequal gap die surface compensation, and pressure equipment deflection compensation. It enables multiple splicing of lightweight materials or ordinary plates to achieve one-time mold forming in a low-cost, high-quality mode, providing a simple operation solution for the application of new materials and deep cost reduction in automobiles, and also providing strong technical support for the lightweight, green, low-carbon and sustainable upgrading of automobiles.

[0021] This invention innovatively incorporates a deflection analysis and compensation database system for different press differences. Building upon traditional automotive body panel mold manufacturing technology, it innovates and conducts batch experiments on the forming, calculation, and process debugging methods for multi-joint materials. Utilizing the digital reverse engineering experience of molding craftsmen from various automotive body panels, it employs a systematic approach including main trend analysis of parts, construction of dispersed slip drawbeads, reverse material feeding compensation, progressive transition zones, unequal gap die surface compensation, and press deflection compensation. This addresses the high-quality forming challenges of multi-thickness splicing, lightweight material splicing, and splicing of different materials. This invention is applicable to splicing and triple splicing of ordinary steel plates, aluminum plates, and magnesium-aluminum plates. The sheet thickness used in the experiments ranged from 0.6 to 2.5 mm. The main processes of this invention are as follows: A method for mold forming and manufacturing multi-joint automotive body panels, such as... Figure 1As shown, it includes the following steps: Step 1: Main trend analysis; This mainly involves analyzing the overall shape of the parts and the direction of the splicing panels, using the splicing direction line as the main direction line, and taking the highest point of the parts as the center to explore the trend outline. Step 2: Constructing the dispersed slip drawbar; Step 3, Reverse material feeding compensation; Reverse material feeding compensation is mainly for the material feeding setting in the splicing joint direction. It optimizes the shape of both sides of the joint to ensure that the material feeding area is outside the joint, so as to ensure that the joint area does not deform or deforms less. Step 4, Gradual Transition Zone; The purpose of the gradual transition zone is to create a gap at the joint position to prevent the thicker plate area from sliding into the thinner plate area at the joint position and causing cracks or scratches. However, if the transition zone is too large, it is easy to cause insufficient forming or product defects. Therefore, the setting of the transition zone should be adjusted according to the material thickness and shape. Step 5: Unequal gap die surface compensation; Unequal gap die surface compensation is mainly for the punch and vertical surface. The overall die gap is controlled according to the shape of the part to achieve a dynamic full fit under the deformation of the die under pressure, so as to ensure the forming quality of the part. The compensation is divided into two types: center surface compensation and vertical surface compensation. Step 6: Pressure Equipment Deflection Compensation; Pressure equipment deflection compensation involves establishing a machine tool deflection cloud map based on the difference between the deflection of the pressure equipment workbench on the manufacturing production line and the deflection of the pressure equipment at the mold manufacturing stage, forming a deflection parameter module, and performing corresponding deflection compensation on the part punch, so that no machine error variation occurs after the mold enters the production line, ensuring product quality.

[0022] Based on the above implementation method, as a preferred implementation method, step 1 specifically includes the following steps: Step 1.1: Construct splicing direction array lines; extract the splicing line of the part as the baseline, and then make a parallel line array with a spacing of 100mm. At the same time, construct lines along the vertical direction of the array line at 100mm intervals until the entire part area is covered, forming the splicing direction array lines. Step 1.2: Using the highest point of the part as the center, construct a cone or trapezoidal body according to the shape of the part as an envelope to cover the entire part. If the part shape is similar to a basin, construct a cone; if the part shape is similar to a box, construct a trapezoid. Move the envelope down to the top 15-25mm away from the highest point. Step 1.3: Construct a plane with the splicing direction array lines to form an intersecting surface with the envelope. The intersection line is used as a trend line. Break the intersection line with the splicing direction array lines to form line segments. Translate each line segment to the edge of the part outline. Connect the middle part of the adjacent line segments with the splicing direction array lines to form the main trend outline of the part, thus completing the main trend analysis.

[0023] Based on the above implementation method, as a preferred implementation method, the specific method of step 2 includes: taking the conventional part's drawbead arrangement position as a reference position, and taking the main trend contour line as the main direction, optimizing the rounding, and smoothly transitioning the drawbead to form a drawbead whose trend is similar to the main trend contour line; the drawbead can be designed as a square rib or a round rib according to the part characteristics, but the drawbead width needs to be consistent and cannot be a gradient drawbead; when the drawbead locking material is insufficient, a drawbead array is made to generate multiple drawbeads, but the width of the drawbead, except for the end part, needs to be consistent, and the drawbead spacing is between 25-35mm.

[0024] Based on the above implementation method, as a preferred implementation method, the reverse material compensation method in step 3 includes method 3.1, dual material splicing. A return arc compensation surface along the large deformation trend of the main body of the part is constructed outside the part area on both sides of the splice. The reverse arc surface is optimized according to the shape of the part and the position of the drawbead is adjusted to form a force trend area opposite to the direction of the part. By expanding the drawbead array, the locking force of different areas is adjusted to ensure that the splice does not deform or the deformation is translated in the same direction. However, the overall translation amount does not exceed 3mm, and the translation can only move in the direction of thicker material. This process requires batch compensation optimization and drawbead position adjustment. The CAE result is selected as the process model after CAE analysis to select the optimal effect.

[0025] Based on the above implementation method, as a preferred implementation method, the anti-material feeding compensation method in step 3 also includes method 3.2. For multi-material splicing, in addition to using the above method, it is also necessary to select a waste area in the middle splicing material area to construct a small convex and concave structure. The shape of this structure is used to stabilize the material feeding, thereby preventing irregularity in the material feeding. The construction mode is to find a waste area near the middle material feeding area that exceeds 3mm and set a convex and concave shape. Its height is set to preferably pull the seam back to the original position according to CAE analysis. Pull back along the shaping point so that the offset is controlled within 3mm.

[0026] Based on the above implementation method, as a preferred implementation method, the anti-feed compensation method in step 3 also includes: Method 3.3, for parts with complex shape changes and difficult anti-feed pullback, by optimizing the shape of the part, smoothing the shape of the part without affecting the strength and function of the part, and performing deformation optimization according to molding requirements and part matching requirements.

[0027] Based on the above implementation method, as a preferred implementation method, the transition area setting method in step 4 is as follows: a 3mm gap is set from the side with greater thickness to the side with less thickness. The gap in this area is set according to the thickness of the thick material. A gradual gap transition is made from the outside of the 3mm area to the direction of the thin material. The width of the transition area is calculated according to the following formula: the width of the transition area D = (thick material thickness - thin material thickness) * 2.5.

[0028] Based on the above implementation method, as a preferred implementation method, the center surface compensation method in step 5 is as follows: Step 5.1, Center Surface Compensation; Taking the highest point of the part as the center and the middle plane as the area, a gradual bulge is made on the shape of the punch. The center height of the gradual bulge is the maximum bulge height, and the maximum bulge height is calculated according to the following formula: Maximum bulge height H = material thickness * 0.3 * longest diameter of the central planar area / 500.

[0029] Based on the above implementation method, as a preferred implementation method, the facade compensation method in step 5 is as follows: Step 5.2, facade compensation; facade compensation is performed when the facade angle is above 45 degrees, and the method is to gradually expand the facade area from the bottom of the facade upwards, and the expansion amount is the distance from the top of the facade as the maximum expansion amount. The maximum expansion amount is calculated as follows: maximum expansion amount L = facade angle % * material thickness * 0.17.

[0030] Based on the above implementation method, as a preferred implementation method, the pressure equipment deflection compensation in step 6 is divided into two stages: process mold surface compensation and debugging simulation compensation, as follows: Step 6.1, Process Die Surface Compensation; This mainly involves calculating the approximate deflection based on the structure of the upper and lower worktables of the equipment and the dimensions of the die. The deflection Ymax1 of the pressure equipment worktable in the manufacturing production line and the deflection Ymax2 of the pressure equipment in the die manufacturing stage are used. Based on the ratio of the deflections of the two pieces of equipment, the maximum height of the die punch's rise or fall is determined. Then, the punch is gradually raised or lowered as a whole, with the center point of the rise or fall being the center point of the die. The selection of the rise or fall and the method for calculating the height are as follows: If Ymax1 > Ymax2, the price rises; conversely, if Ymax1 is lower than Ymax2, the price falls. Height h = Ymax1 / Ymax2 * mold length / 1000 * 0.2 + Ymax1 / Ymax2 * 0.1; Step 6.2: Debugging and simulation compensation. If the punch bulges during debugging, add a shim with a mold length of 30% and a thickness of h in the middle of the punch; if the punch sags, add shims with a width of 15% of the mold length and a thickness of h to both ends of the mold along its length.

[0031] All aspects not detailed in this invention are conventional technical means known to those skilled in the art.

[0032] The above content shows and describes the basic principles, main features, and beneficial effects of the present invention. The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for manufacturing a multi-joint automotive body panel using mold forming, characterized in that... Includes the following steps: Step 1: Main trend analysis; This mainly involves analyzing the overall shape of the parts and the direction of the splicing panels, using the splicing direction line as the main direction line, and taking the highest point of the parts as the center to explore the trend outline. Step 2: Constructing the dispersed slip drawbar; Step 3, Reverse material feeding compensation; Reverse material feeding compensation is mainly for the material feeding setting in the splicing joint direction. It optimizes the shape of both sides of the joint to ensure that the material feeding area is outside the joint, so as to ensure that the joint area does not deform or deforms less. Step 4, Gradual Transition Zone; The purpose of the gradual transition zone is to create a gap at the joint position to prevent the thicker plate area from sliding into the thinner plate area at the joint position and causing cracks or scratches. However, if the transition zone is too large, it is easy to cause insufficient forming or product defects. Therefore, the setting of the transition zone should be adjusted according to the material thickness and shape. Step 5: Unequal gap die surface compensation; Unequal gap die surface compensation is mainly for the punch and vertical surface. The overall die gap is controlled according to the shape of the part to achieve a dynamic full fit under the deformation of the die under pressure, which is suitable for different material thickness changes and the deformation state of the die under stress, thereby ensuring the forming quality of the part. The compensation is divided into two types: center surface compensation and vertical surface compensation. Step 6: Pressure Equipment Deflection Compensation; Pressure equipment deflection compensation involves establishing a machine tool deflection cloud map based on the difference between the deflection of the pressure equipment workbench on the manufacturing production line and the deflection of the pressure equipment at the mold manufacturing stage, forming a deflection parameter module, and performing corresponding deflection compensation on the part punch, so that no machine difference variation occurs after the mold enters the production line, ensuring product quality.

2. The mold forming manufacturing method for multi-joint automotive body panels according to claim 1, characterized in that... The specific method of step 1 includes the following steps: Step 1.1: Construct splicing direction array lines; extract the splicing line of the parts as the baseline, and then make a parallel line array with a spacing of 100mm. At the same time, construct lines along the vertical direction of the array lines at 100mm intervals until the entire part area is covered, forming the splicing direction array lines. Step 1.2: Using the highest point of the part as the center, construct a cone or trapezoidal body according to the shape of the part as an envelope to cover the entire part. If the part shape is similar to a basin, construct a cone; if the part shape is similar to a box, construct a trapezoid. Move the envelope down to the top 15-25mm away from the highest point. Step 1.3: Construct a plane with the splicing direction array lines to form an intersecting surface with the envelope. The intersection line is used as a trend line. Break the intersection line with the splicing direction array lines to form line segments. Translate each line segment to the edge of the part outline. Connect the middle part of the adjacent line segments with the splicing direction array lines to form the main trend outline of the part, thus completing the main trend analysis.

3. The mold forming manufacturing method for multi-joint automotive body panels according to claim 1 or 2, characterized in that... The specific method of step 2 includes: taking the position of the drawbead arrangement of conventional parts as a reference position, optimizing the rounding with the main trend contour line as the main direction, and smoothly transitioning the drawbead to form a drawbead whose trend is similar to the main trend contour line; the drawbead can be designed as square or round ribs according to the characteristics of the part, but the width of the drawbead needs to be consistent and cannot be made into a gradient drawbead; when the drawbead locking material is insufficient, a drawbead array is made to generate multiple drawbeads, but the width of the drawbead needs to be consistent except at the end, and the spacing between the drawbeads is between 25-35mm.

4. The mold forming manufacturing method for multi-joint automotive body panels according to claim 3, characterized in that: The anti-feedback compensation method in step 3 includes: Method 3.1: Dual-material splicing. Construct a reverse arc compensation surface outside the part area on both sides of the splice, along the large deformation trend of the main body of the part. Optimize the reverse arc surface according to the shape of the part and adjust the position of the drawbeads to form a force trend zone opposite to the direction of the part. Expand the drawbead array to adjust the locking force in different areas, thereby ensuring that the splice does not deform or the deformation is translated in the same direction. However, the overall translation amount does not exceed 3mm, and the translation can only move in the direction of thicker material. This process requires batch compensation optimization and drawbead position adjustment. Select the optimal effect through CAE analysis and confirm the CAE result as the process model.

5. The mold forming manufacturing method for multi-joint automotive body panels according to claim 4, characterized in that: The anti-feedback compensation method in step 3 also includes: Method 3.2: For multi-material splicing, in addition to the above method, it is also necessary to select a waste area in the middle splicing material area to construct a small convex and concave structure. The shape of this structure is used to stabilize the material flow and prevent irregularity of the material flow. The construction mode is to find a waste area near the middle material flow area that exceeds 3mm and set a convex and concave shape. Its height is set to be preferably pulled back to the original position according to CAE analysis. Pull back along the shaping point to control the offset within 3mm.

6. The mold forming manufacturing method for multi-joint automotive body panels according to any one of claims 1-2 and 4-5, characterized in that: The anti-feedback compensation method in step 3 also includes: Method 3.3: For parts with complex shapes that are difficult to reverse and pull back, optimize the part shape, smooth the part shape without affecting the part's strength and function, and perform deformation optimization according to molding requirements and part matching requirements.

7. The mold forming manufacturing method for multi-joint automotive body panels according to claim 6, characterized in that: The transition area setting method in step 4 is as follows: a 3mm gap is set from the side with greater thickness to the side with less thickness. The gap in this area is set according to the thickness of the thick material. A gradual gap transition is made from the outside of the 3mm area to the direction of the thin material. The width of the transition area is calculated according to the following formula: transition area width D = (thick material thickness - thin material thickness) * 2.

5.

8. The mold forming manufacturing method for multi-joint automotive body panels according to any one of claims 1-2, 4-5, and 7, characterized in that: The center surface compensation method in step 5 is as follows: Step 5.1, Center Surface Compensation; Taking the highest point of the part as the center and the middle plane as the area, a gradual bulge is made on the shape of the punch. The center height of the gradual bulge is the maximum bulge height, which is calculated according to the following formula: Maximum bulge height H = material thickness * 0.3 * longest diameter of the central plane area / 500.

9. The mold forming manufacturing method for multi-joint automotive body panels according to any one of claims 1-2, 4-5, and 7, characterized in that: The facade compensation method in step 5 is as follows: Step 5.2, facade compensation; facade compensation is carried out when the facade angle is above 45 degrees. The method is to gradually expand the facade area from the bottom of the facade upwards. The expansion amount is the distance from the top of the facade, which is the maximum expansion amount. The maximum expansion amount is calculated as follows: maximum expansion amount L = facade angle % * material thickness * 0.

17.

10. The mold forming manufacturing method for multi-joint automotive body panels according to claim 1, characterized in that: The pressure equipment deflection compensation in step 6 is divided into two stages: process mold surface compensation and debugging simulation compensation, as follows: Step 6.1, Process Die Surface Compensation; This mainly involves calculating the approximate deflection based on the structure of the upper and lower worktables of the equipment and the dimensions of the die. The deflection Ymax1 of the pressure equipment worktable in the manufacturing production line and the deflection Ymax2 of the pressure equipment in the die manufacturing stage are used. Based on the ratio of the deflections of the two pieces of equipment, the maximum height of the die punch's rise or fall is determined. Then, the punch is gradually raised or lowered as a whole, with the center point of the rise or fall being the center point of the die. The selection of the rise or fall and the method for calculating the height are as follows: If Ymax1 > Ymax2, the price rises; conversely, if Ymax1 is lower than Ymax2, the price falls. Height h = Ymax1 / Ymax2 * mold length / 1000 * 0.2 + Ymax1 / Ymax2 * 0.1; Step 6.2: Debugging and simulation compensation. If the punch bulges during debugging, add a shim with a mold length of 30% and a thickness of h in the middle of the punch; if the punch sags, add shims with a width of 15% of the mold length and a thickness of h to both ends of the mold along its length.

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