Rebound control method for engine hood outer panel, flanging die and vehicle

Abstract

The present invention relates to the technical field of vehicle body forming, and specifically to a method for controlling the rebound of an aluminum hood outer panel, a flanging die, and a vehicle. The method comprises: using a flanging punch and an upper blanking plate to press the area of ​​the hood outer panel except the flanging area, and using a flanging die and a full-circumference blanking plate to press the flanging area of ​​the hood outer panel, so that the flanging area of ​​the hood outer panel completes the flanging process in a clamped state, and avoids the huge rebound caused by the lateral shear stress released by the free flanging of the arc area; the present invention adjusts the curvature radius, sets auxiliary ridges, and increases the height and range of the main ridges; the rebound amount is reduced to a controllable range of risks at the manufacturing end, and the wave problem near the main ridges can be eliminated. The present invention can solve the huge rebound problem of aluminum hoods during the industrialization stage, help improve the assembly accuracy of the hood, reduce assembly gaps, and improve the appearance quality of the entire vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle body molding, and in particular to a rebound control method for an engine hood outer panel, a flanging die, and a vehicle. Background Art

[0002] The hood outer panel is one of the main parts of the front part of a passenger car. Due to its strong correlation with styling and pedestrian protection properties, it is also an important medium- and long-cycle covering component (especially the aluminum alloy hood outer panel, which is a long-cycle part on the manufacturing end). It is a key part of CAS review and simultaneous engineering work in the early stages of vehicle development.

[0003] However, the stamping SE analysis in the CAS stage shows that there is a huge rebound in the outer panel of the hood, such as Figure 2 As shown; the maximum rebound at the rear is 27mm, the maximum rebound at both ends is -28mm, and the height difference reaches 55mm, which is related to the material properties of the aluminum plate.

[0004] The springback problem of the hood outer panel is a common stamping quality problem, which is generally solved by using a springback compensation solution. Since the elastic modulus of aluminum sheet is 1 / 3 of that of steel sheet, if springback compensation is used to solve the above springback problem, the large amount of local compensation and the opposite direction of compensation at both ends and in the middle will cause large changes in the curvature of the processing die surface and the product. Since the curvature of the hood outer panel is the main factor affecting the springback amount, each time the part is compensated, a new and different springback result will be produced. This is also the difficulty in rectifying the springback problem of the aluminum hood outer panel. During the actual debugging process, the above-mentioned problem of random changes in springback amount occurs, and after multiple springback compensation debugging, the parts still cannot meet the acceptance standards. After the hood outer panel is pressed onto the inner panel to form an assembly, the dimensional tolerance problem of the hood outer panel is improved and can be installed on the vehicle, but the gap between the inner and outer panels is uneven, which affects the coating of the shock-absorbing glue of the inner and outer panels and causes quality problems such as overflow of glue. Summary of the Invention

[0005] In view of the above shortcomings of the prior art, the object of the present invention is to provide a rebound control method for an engine hood outer panel, a flanging die and a vehicle, so as to improve the problem of huge rebound generated after the engine hood outer panel is flanging.

[0006] To achieve the above and other related objectives, the present invention provides a method for controlling the rebound of an engine hood outer panel, comprising:

[0007] During the flanging forming process of the hood outer panel, the flanging punch and the upper pressure plate are used to press the area of ​​the hood outer panel except the flanging area, and the flanging die and the full-circumference pressure plate are used to press the flanging area on the hood outer panel, so that the material in the flanging area is clamped by the flanging die and the full-circumference pressure plate, and gradually flows into the gap between the flanging punch and the flanging die along the gap between the flanging die and the full-circumference pressure plate to form a flanging.

[0008] In an optional embodiment of the present invention, it also includes using three-dimensional modeling software to perform curvature analysis on the outer panel of the engine hood, and adjusting the curvature radius so that the curvature radius of any area on the outer panel of the engine hood is smaller than a first critical value, or the diameter of the area on the outer panel of the engine hood whose curvature radius is greater than the first critical value is smaller than a preset value.

[0009] In an optional embodiment of the present invention, the first critical value is 9000 mm; the preset value is 150 mm.

[0010] In an optional embodiment of the present invention, the curvature radius of the area on the engine hood outer panel where the curvature radius is greater than the first critical value is less than the second critical value.

[0011] In an optional embodiment of the present invention, the second critical value is 10000 mm.

[0012] In an optional embodiment of the present invention, a main ridge line and an auxiliary ridge line are further provided on the engine hood outer panel, wherein there are two main ridge lines and they are symmetrically arranged about the longitudinal center axis of the engine hood outer panel, and the auxiliary ridge line is located between the two main ridge lines.

[0013] In an optional embodiment of the present invention, the distance L1 between the two main ridges is less than 900 mm; there is one auxiliary ridge, and the auxiliary ridge is located on the longitudinal center axis of the engine hood outer panel.

[0014] In an optional embodiment of the present invention, the distance L1 between the two main ridges is less than 900 mm; there are two auxiliary ridges, the two auxiliary ridges are symmetrically arranged about the longitudinal center axis of the engine hood outer panel, and the distance L2 between the two auxiliary ridges is less than 600 mm.

[0015] To achieve the above-mentioned and other related purposes, the present invention further provides a flanging die, comprising an upper die and a lower die;

[0016] The upper mold comprises:

[0017] A flanging die, wherein the flanging die is annular and has a contour shape identical to that of the flanging area of ​​the engine hood outer panel edge;

[0018] An upper blank holder, the upper blank holder being located within the area enclosed by the flanging die, the upper blank holder having the same contour shape as the hood outer panel, and being movably arranged up and down relative to the die;

[0019] The lower die comprises:

[0020] a flanging punch having the same contour shape as the engine hood outer panel;

[0021] A full-circumference blank holder, the full-circumference blank holder being arranged around the edge of the flanging punch and being movable up and down relative to the flanging punch;

[0022] The driving mechanism is used to drive the upper mold and the lower mold to perform relative opening and closing movements.

[0023] In an optional embodiment of the present invention, the flanging punch is fixed to the lower die base, the full-circumference pressure plate is movably connected to the lower die base, and when the upper die and the lower die are in the closed state, a gap of 1-2 mm is provided between the bottom surface of the full-circumference pressure plate and the top surface of the lower die base.

[0024] To achieve the above-mentioned and other related purposes, the present invention further provides a vehicle, comprising:

[0025] vehicle body;

[0026] An engine hood, mounted above the engine compartment of the vehicle body, the engine hood comprising an outer panel and an inner panel;

[0027] The curvature radius of any area on the outer panel of the engine hood is smaller than a first critical value, or the diameter of the area on the outer panel whose curvature radius is larger than the first critical value is smaller than a preset value;

[0028] The outer panel is provided with a main ridgeline and an auxiliary ridgeline, wherein the main ridgelines are two and are symmetrically arranged about the longitudinal center axis of the hood outer panel, and the auxiliary ridgeline is located between the two main ridgelines;

[0029] The outer panel edge is provided with a flange, and the flange is formed by the following method: the area other than the flange area on the engine hood outer panel is pressed by a flange punch and an upper pressure plate respectively, and the flange area on the engine hood outer panel is pressed by a flange die and a full-circumference pressure plate respectively, so that the material in the flange area is clamped by the flange die and the full-circumference pressure plate, and gradually flows into between the flange punch and the flange die along the gap between the flange die and the full-circumference pressure plate to form a flange.

[0030] To summarize, the flanging mold structure of the present invention is designed as a full-circumference pressing and flanging structure, so that the material-deficient and multi-material flanging areas on the front and rear sides of the engine hood are flanging under the action of the full-circumference pressing plate, avoiding the huge rebound caused by the release of the lateral shear stress of the free flanging, which helps to improve the assembly accuracy of the engine hood, reduce the assembly gap, and improve the appearance quality of the whole vehicle; in addition, under the premise of ensuring the family characteristics of the styling, the present invention reduces the curvature radius of the front windshield position of the aluminum engine hood outer panel, increases the ridges, and increases the height and range of the main ridges, so that the rebound amount is reduced to the controllable range of the manufacturing risk, and can eliminate the wave problem near the main ridges. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 It is a schematic diagram of the structure of an engine hood outer panel;

[0033] Figure 2 yes Figure 1 The figure shows a schematic diagram of the rebound simulation of the hood outer panel. The dark areas in the figure indicate areas with severe rebound, and the positive and negative rebound values ​​indicate the rebound direction.

[0034] Figure 3 This is a schematic diagram of the curvature radius distribution of the engine hood outer panel before structural optimization. The dark area in the figure represents the area with a curvature radius greater than 9000mm;

[0035] Figure 4 FIG1 is a schematic diagram of the curvature radius distribution of the engine hood outer panel after the mechanism optimization provided by an embodiment of the present invention. The dark area in the figure represents the area with a curvature radius greater than 9000 mm.

[0036] Figure 5 This is a schematic structural diagram of an engine hood outer panel with auxiliary ridges provided by one embodiment of the present invention;

[0037] Figure 6 is a schematic structural diagram of an engine hood outer panel with auxiliary ridges provided by another embodiment of the present invention;

[0038] Figure 7 1 is a schematic structural diagram of a flanging die provided by an embodiment of the present invention, wherein only the die surface at the junction with the engine hood outer panel is shown;

[0039] Figure 81 is a schematic diagram of a positioning structure for the flanging process of an engine hood outer panel provided by an embodiment of the present invention;

[0040] Figure 9 This is a schematic diagram of the flanging mold provided by an embodiment of the present invention before mold closing;

[0041] Figure 10 This is a schematic diagram of a local area of ​​a corner during the closing process of a flanging mold provided by an embodiment of the present invention;

[0042] Figure 11 This is a schematic diagram of a local area of ​​a corner of a flanging mold after mold closing provided by an embodiment of the present invention;

[0043] Figure 12 Schematic diagram of the distribution of the main ridge heightened area provided by an embodiment of the present invention;

[0044] Figure 13 yes Figure 12 AA cross-sectional view.

[0045] Component number description:

[0046] 10. Engine hood outer panel; 101. Front arc area; 102. Rear arc area; 103. Front arc area; 104. Sharp point; 105. Lamp socket; 11. Flanging area; 12. Main edge line; 13. Auxiliary edge line; 20. Upper die; 21. Upper pressure plate; 22. Flanging die; 30. Lower die; 31. Flanging punch; 32. Full-circle pressure plate; 40. Positioning block. DETAILED DESCRIPTION

[0047] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following examples and the features in the examples can be combined with each other unless they conflict. It should also be understood that the terms used in the examples of the present invention are for the purpose of describing specific embodiments, not for the purpose of limiting the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0048] See also Figures 1 to 12. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0049] In the description of the present invention, the expressions indicating directions such as "longitudinal", "lateral", and "vertical" have the same meaning as the general definition of various directions of a vehicle in this field. The "longitudinal" refers to the length direction of the vehicle, that is, the X direction; the "lateral" refers to the width direction of the vehicle, that is, the Y direction; and the "vertical" refers to the height direction of the vehicle, that is, the Z direction.

[0050] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those described in the examples of the present invention may also be used to implement the present invention.

[0051] See also Figure 4-12 As shown, the present invention provides a method for controlling the rebound of the engine hood outer panel 10. It should be noted that the profile of the engine hood outer panel 10 used in this embodiment is as follows: Figure 1 As shown, its edge profile includes a front arc area 101 located at the front side; a rear arc area 102 located at the rear side; front arc areas 103 located on both sides; a sharp point 104 located between the front arc area 103 and the rear arc area 102; and a lamp base 105 located between the front arc area 101 and the front arc area 103. To solve the problem of springback after flanging, the present invention mainly improves from the following two aspects:

[0052] In terms of process design: the flanging die structure of the aluminum hood outer panel 10 is designed as a full-circumference pressing and flanging structure; the short-material and multi-material flanging areas 11 on the front and rear sides of the hood are flanging under the action of the full-circumference pressing plate 32, avoiding the free flanging lateral shear stress release causing the flanging process parts of the hood outer panel 10 to produce a huge rebound amount, reducing the rebound amount from 55mm to 10mm.

[0053] In terms of product design: Under the premise of ensuring the family characteristics of the styling, by reducing the curvature radius of the front windshield position of the aluminum engine hood outer panel 10 and increasing the height and range of the main ridge line 12, the rebound amount is reduced from 10mm to a controllable range of manufacturing risk, and the wave problem near the main ridge line 12 can be eliminated.

[0054] Specifically:

[0055] See also Figure 3 、 4 As shown, the present invention uses three-dimensional modeling software to perform curvature analysis on the engine hood outer panel 10, and adjusts the curvature radius so that the curvature radius of any area on the engine hood outer panel is less than a first critical value, or the diameter of the area on the engine hood outer panel 10 where the curvature radius is greater than the first critical value is less than a preset value.

[0056] It is understandable that the hood outer panel 10 is generally designed to be large and flat, especially the rear portion near the front windshield has a large profile and curvature radius, such as Figure 3 As shown, the curvature radii Rx and Ry of the rear and both sides are generally 10000mm-30000mm. However, from the perspective of drawn parts, the smaller the curvature radius, the greater the material strain value, the more complete the plastic deformation, the better the part rigidity, and the smaller the springback value after drawing and flanging. The curvature radius of the hood outer panel 10 is the main factor affecting the springback. Under the premise of ensuring the styling characteristics, the hood outer panel 10 is designed with a smaller curvature radius as much as possible, especially at the rear front windshield position; as shown in FIG. Figure 4 As shown, the ideal curvature standard of the engine hood outer panel 10 parts defined by the present invention is as follows:

[0057] (1) Most areas (i.e. Figure 4 The curvature radius Rx and Ry of the light-colored area (in the figure) are less than 9000 mm;

[0058] (2) The area that does not meet condition (1) (i.e. Figure 4 The diameter of the dark areas in the image is less than 150 mm; at the same time, the curvature radii Rx and Ry of these areas are best less than 10000 mm.

[0059] It should be noted that the outline of the area that does not meet condition (1) is not necessarily a standard circle. The diameter of the area mentioned in the present invention should be understood as the diameter of a virtual circular area that roughly covers the area, for example, it can be a minimum circumscribed circle diameter of the area in the vertical projection direction.

[0060] See also Figure 5 、 6As shown, the present invention sets a main ridge line 12 and an auxiliary ridge line 13 on the engine hood outer panel 10. There are two main ridge lines 12 and they are symmetrically arranged about the longitudinal center axis of the engine hood outer panel 10. The auxiliary ridge line 13 is located between the two main ridge lines 12.

[0061] It is understandable that as an important styling feature, obvious ridges are designed on both sides of the hood outer panel 10, which are generally referred to as main ridges 12; the ridges added by the present invention are designed in the middle position between the two main ridges 12. Because they are weaker than the main ridges 12 in terms of styling and visual effects, they are called auxiliary ridges 13. The auxiliary ridges 13 divide the large curvature surface at the rear of the hood outer panel 10; at the same time, because the ridge curvature radius is very small, the ridge area has good rigidity after forming, which has a good supporting effect on the nearby surface, thereby improving the surface rebound problem in the above-mentioned area. The auxiliary ridges 13 defined by the present invention are as follows:

[0062] (1) Double auxiliary edge line 13 scheme: two auxiliary edge lines 13 symmetrical about the X axis, such as Figure 6 As shown, the distance L1 of the main edge 12 is recommended to be <900mm, and the distance L2 of the auxiliary edge 13 is recommended to be <600mm.

[0063] (2) Single auxiliary edge 13 scheme: The auxiliary edge 13 coincides with the X-axis, such as Figure 5 As shown, the distance L1 from the main edge line 12 is recommended to be less than 900 mm.

[0064] See also Figure 11 、 12 As shown, the height and width of the ridge design are also a factor that affects the nearby profiles. The optimization of the profile curvature radius solves the main rebound problem, but the profiles on both sides of the main ridge 12 and the middle X-axis profile form profile waves: the ridge and the X-axis position are high points, and there are pits on both sides of the ridge. If the positioning reference point of the product is not set properly, it is easy to cause the constrained rebound waves to intensify. This kind of wave problem in a small range will cause new waves during rebound compensation, affecting the surface quality of the entire hood outer panel. The wave problem on both sides of the main ridge 12 of the present invention is solved by increasing the height and range of the ridge, as shown in Figures 11 and 12:

[0065] 1) The heightened area is at the wave position behind the ridge line, and the front ridge line has a smooth transition height.

[0066] 2) The ridges are shifted upward as a whole, keeping the original ridge angle and ridge radius unchanged to avoid the generation of slip lines.

[0067] 3) The height of the ridge line is increased by 1.5-2.5mm on the original basis, with the critical value being that no obvious slip line is produced.

[0068] 4) The ridge width is also increased accordingly, which makes the ridge influence range larger and improves the overall rigidity of the part.

[0069] After optimization using the method of the present invention, the rebound value of the aluminum engine hood outer panel 10 in the modeling stage can be reduced to (-3,3), which not only ensures the family characteristics of the modeling such as the main edge line 12 and curvature, but also avoids the major quality risks of the aluminum alloy engine hood outer panel 10 at the manufacturing end.

[0070] See also Figure 7-11 As shown, during the flanging forming process of the hood outer panel 10, the flanging punch 31 and the upper pressing plate 21 are used to press the area other than the flanging area 11 on the hood outer panel 10, and the flanging die 22 and the full-circumference pressing plate 32 are used to press the flanging area 11 on the hood outer panel 10. Under the clamping of the flanging die 22 and the full-circumference pressing plate 32, the material of the flanging area 11 gradually flows from the gap between the flanging die 22 and the full-circumference pressing plate 32 into the gap between the flanging punch 31 and the flanging die 22 to form a flanging.

[0071] like Figure 7-11 As shown, the front bumper and rear windshield of the hood outer panel 10 are designed as a large arc area with short straight line areas on both sides. Although the flange height of the aluminum hood outer panel 10 before lamination is only 10mm, the lateral shear stress release after the front and rear sides are short of material and the multiple materials are flanging causes a huge amount of rebound in the flanging process of the hood outer panel 10. In order to control the rebound, it is necessary to control the flow of material during the flanging process and avoid flanging in a free state of the material. The solution of the present invention is to add a pressing plate around the flanging lower die 30 with a pressing force of 20T and a stroke of 20mm. The full-circle pressing plate 32 can complete the flanging of the material in a clamped state, controlling the radial stretching and lateral shear deformation of the material. The rebound after flanging is reduced from the original (-28, 27) to (-5, 7.5), which is a significant improvement.

[0072] Further, such as Figure 10 、 11 As shown, the flanging punch 31 is fixed to the lower die seat (not shown in the figure), and the full-circumference pressure plate 32 is movably connected to the lower die seat. When the upper die and the lower die are in the closed state, a gap of 1-2 mm is provided between the bottom surface of the full-circumference pressure plate 32 and the top surface of the lower die seat. The main function of the full-circumference pressure plate 32 is to control the material flow of the flanging area 11 during the flanging bending process. As the flanging die 22 descends, the material 11 in the flanging area is clamped by the full-circumference pressure plate 32 and gradually flows into between the flanging die 22 and the flanging punch 32. The sheet material 11 is completely separated from the full-circumference pressure plate 32 in the closed state. The existence of the gap can ensure that after the full-circumference pressure plate 32 is separated from the material 11, there is a certain safety gap between it and the lower die 30.

[0073] Please refer to Figures 7-11. Based on the above-mentioned flanging process, the present invention provides a flanging mold, including an upper mold 20 and a lower mold 30; the upper mold 20 includes: a flanging die 22, the flanging die 22 is annular, and the contour shape of the flanging die 22 is the same as the contour shape of the flanging area 11 at the edge of the engine hood outer panel 10; an upper pressing plate 21, the upper pressing plate 21 is located in the area surrounded by the flanging die 22, the upper pressing plate 21 is the same as the contour shape of the engine hood outer panel 10, and the upper pressing plate 21 is movably arranged up and down relative to the die; the lower mold 30 includes: a flanging punch 31, the flanging punch 31 is the same as the contour shape of the engine hood outer panel 10; a full-circumference pressing plate 32, the full-circumference pressing plate 32 is arranged around the edge of the flanging punch 31, and the full-circumference pressing plate 32 is movably arranged up and down relative to the flanging punch 31.

[0074] Combine Figure 7-11 The specific working process of the flanging mold is described in detail: first, the hood outer panel 10 is placed on the lower mold 30 and fixed with a positioning block 40; the upper mold 20 is driven by a driving mechanism (such as a press) to move downward as a whole until the upper pressure plate 21 and the flanging punch 31 are closed. It should be noted that elastic components (such as nitrogen springs, etc.) should be provided between the upper pressure plate 21 and the upper mold 20 seat and between the full-circle pressure plate 32 and the lower mold 30 seat to ensure that when the flanging punch 31 and the upper pressure plate 21 are closed, the flanging die 22 can continue to move downward. At this time, the flanging die 22 and the flanging punch 31 apply longitudinal tension to the material of the flanging area 11 of the hood outer panel 10, and the flanging area 11 begins to bend downward. The arc areas 101, 102 and 105 of the bending area generate transverse shear force. At the same time, the flanging area 11 is clamped between the flanging die 22 and the full-circle pressure plate 32 Between them, the two can control the material of the flanging area 11 to gradually flow into between the flanging die 22 and the flanging punch 31, eliminate the influence of the lateral shear force, and the sheet material 11 is completely separated from the full-circumference pressing plate 32 during the mold closing stage. The flanging formed in this way can greatly reduce springback; finally, the upper mold 20 is driven upward by the press, and the lower mold 30 is separated from the upper mold 20, and the engine hood outer panel 10 is removed from the flanging punch 31, and the flanging process is completed.

[0075] Based on the above-mentioned hood outer panel 10, the present invention also provides a vehicle, comprising a vehicle body and a hood; the hood is mounted above the engine compartment of the vehicle body, and the hood comprises an outer panel and an inner panel; the diameter of the area on the outer panel where the radius of curvature is greater than the first critical value is less than a preset value; a main ridgeline 12 and an auxiliary ridgeline 13 are provided on the outer panel, the main ridgelines 12 being two and symmetrically arranged about the longitudinal center axis of the hood outer panel 10, and the auxiliary ridgeline 13 being located between the two main ridgelines 12; the outer panel edge A flange is provided, and the flange is formed by the following method: the area of ​​the hood outer panel 10 other than the flange area 11 is pressed tightly using the flange punch 31 and the upper blanking plate 21, and the flange area 11 of the hood outer panel 10 is pressed tightly using the flange die 22 and the full-circle blanking plate 32, so that the material of the flange area 11 is clamped by the flange die 22 and the full-circle blanking plate 32 and gradually flows into the gap between the flange punch 31 and the flange die 32 along the gap between the flange die 22 and the full-circle blanking plate 32 to form a flange. It can be understood that the anti-rebound design of the vehicle's hood outer panel 10 can effectively reduce the body assembly gap and improve the overall appearance quality of the vehicle.

[0076] In summary, the flanging die structure of the present invention is designed as a full-circumference pressing and flanging structure, so that the material-deficient and multi-material flanging areas 11 on the front and rear sides of the engine hood are flanging under the action of the full-circumference pressing plate 32, avoiding the huge rebound caused by the release of the lateral shear stress of the free flanging, which helps to improve the assembly accuracy of the engine hood, reduce the assembly gap, and improve the appearance quality of the whole vehicle; in addition, under the premise of ensuring the family characteristics of the styling, the present invention reduces the radius of curvature of the front windshield position of the aluminum engine hood outer panel 10, increases the ridges and increases the height and range of the main ridges 12, so that the rebound amount is reduced to a controllable range of risks at the manufacturing end, and can eliminate the wave problem near the main ridges 12. Therefore, the present invention effectively overcomes some practical problems in the prior art and has high utilization value and use significance.

[0077] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for controlling the rebound of an engine hood outer panel, characterized in that: include: During the flanging forming process of the hood outer panel, the flanging punch and the upper blank holder are respectively used to press the area of ​​the hood outer panel except the flanging area, and the flanging die and the full-circumference blank holder are respectively used to press the flanging area of ​​the hood outer panel, so that the material of the flanging area gradually flows into the gap between the flanging die and the full-circumference blank holder along the gap between the flanging die and the full-circumference blank holder to form a flanging; wherein, the material-deficient and multi-material flanging areas on the front and rear sides of the hood are flanging under the action of the full-circumference blank holder; The invention also includes providing a main ridgeline and an auxiliary ridgeline on the hood outer panel, wherein the main ridgelines are two and are symmetrically arranged about the longitudinal center axis of the hood outer panel, and the auxiliary ridgeline is located between the two main ridgelines; It also includes using three-dimensional modeling software to perform curvature analysis on the outer panel of the engine hood and adjust the curvature radius so that the curvature radius of any area on the outer panel of the engine hood is less than a first critical value, or the diameter of the area on the outer panel of the engine hood whose curvature radius is greater than the first critical value is less than a preset value.

2. The method for controlling the rebound of an engine hood outer panel according to claim 1, wherein: The first critical value is 9000 mm; the preset value is 150 mm.

3. The method for controlling the rebound of the engine hood outer panel according to claim 2, characterized in that: The curvature radius of the area on the engine hood outer panel where the curvature radius is greater than the first critical value is less than the second critical value.

4. The method for controlling the rebound of an engine hood outer panel according to claim 3, wherein: The second critical value is 10000 mm.

5. The method for controlling the rebound of an engine hood outer panel according to claim 1, wherein: The distance L1 between the two main ridges is less than 900 mm; there is one auxiliary ridge, and the auxiliary ridge is located on the longitudinal center axis of the engine hood outer panel; or there are two auxiliary ridges, and the two auxiliary ridges are symmetrically arranged about the longitudinal center axis of the engine hood outer panel, and the distance L2 between the two auxiliary ridges is less than 600 mm.

6. A flanging die, characterized in that: Including upper die and lower die; The upper mold comprises: A flanging die, wherein the flanging die is annular and has a contour shape identical to that of the flanging area of ​​the engine hood outer panel edge; An upper blank holder, the upper blank holder being located within the area enclosed by the flanging die, the upper blank holder having the same contour shape as the hood outer panel, and being movably arranged up and down relative to the die; The lower die comprises: a flanging punch having the same contour shape as the engine hood outer panel; A full-circumference blank holder, the full-circumference blank holder being arranged around the edge of the flanging punch and being movable up and down relative to the flanging punch; A driving mechanism, used for driving the upper die and the lower die to perform relative opening and closing movements; Wherein, the engine hood outer panel is provided with a main ridgeline and an auxiliary ridgeline, the main ridgelines are two and are symmetrically arranged about the longitudinal center axis of the engine hood outer panel, and the auxiliary ridgeline is located between the two main ridgelines; The flanging punch is fixed to the lower die base, the full-circumference pressure plate is movably connected to the lower die base, and when the upper die and the lower die are in the clamped state, a gap is provided between the bottom surface of the full-circumference pressure plate and the top surface of the lower die base.

7. The flanging die according to claim 6, characterized in that: The flanging punch is fixed to the lower die base, the full-circumference pressure plate is movably connected to the lower die base, and when the upper die and the lower die are in the clamping state, a gap of 1-2 mm is provided between the bottom surface of the full-circumference pressure plate and the top surface of the lower die base.

8. A vehicle, characterized in that: include: An engine hood outer panel manufactured by the rebound control method of an engine hood outer panel according to any one of claims 1-5.

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