Automobile tail energy absorption box, mold and manufacturing method

Abstract

The invention discloses an automobile tail energy absorption box, a mold and a manufacturing method. The automobile tail energy absorption box comprises a supporting plate, the supporting plate is provided with a polygonal cylindrical structure which extends in the third direction, the inner side and the outer side of each connecting position are rounded, the outer side portion of the connecting position of the polygonal cylindrical structure and the supporting plate is subjected to rounded corner treatment, and the supporting plate is provided with at least one set of energy absorption ribs connected with the lower portion of the polygonal cylindrical structure. The die is used for forming the automobile tail energy absorption box and comprises an upper die mechanism and a lower die mechanism. According to the automobile tail energy absorption box, the integrity and reliability of the structure are improved, the complex process that a plurality of parts are manufactured and then assembled is avoided, the manufacturing period is shortened, and the production efficiency is improved; the mold can be locally heated, the risk of product cracking is reduced, the machining efficiency is greatly improved, the machining difficulty is reduced, and the material returning stroke is shortened by at least 70 mm.

Description

Technical Field

[0001] The present invention relates to the field of automobile technology, and in particular to an automobile rear energy absorption box, a mold and a manufacturing method. Background Art

[0002] As one of the main safety parts of a car, the main function of the energy absorption box is to transfer the force borne by the anti-collision beam to the longitudinal beam, while absorbing part of the energy generated during the collision to protect the passenger compartment. This function is usually guaranteed by its own large impact deformation. In other words, the energy absorption box deforms and collapses during the impact, absorbing the kinetic energy brought by the impact end, thereby reducing the energy transmitted to the rear end. Most of the energy absorption boxes of new energy vehicles currently on the market are composed of stamped parts or castings through bolts and welding (such as Figure 1 ), this type of new energy vehicle energy absorption box product has many components, a long manufacturing cycle, and low production efficiency.

[0003] Based on this, it is currently proposed to form the energy absorption box of new energy vehicles in one piece through extrusion forging, which can reduce the number of parts and shorten the manufacturing cycle. However, the existing energy absorption box of new energy vehicles requires higher strength and performance without destroying the organizational streamline of the material. Moreover, due to the high height of the energy absorption box product of new energy vehicles, it is not convenient to withdraw the material. Moreover, because the product is a thin-walled special-shaped structural part, during production, the material flow rate of each part in the mold cavity is different, the stress is easy to concentrate, and the product is easy to crack during the extrusion process, making forging difficult. Summary of the Invention

[0004] The purpose of the present invention is to provide a car rear energy absorption box, a mold and a manufacturing method to solve the problems raised in the above background technology.

[0005] To achieve the above objectives, the present invention is implemented through the following technical means:

[0006] A car rear energy absorption box includes a support plate, on which is provided a polygonal tubular structure extending along a third direction and having rounded inner and outer corners at each connection; the outer corners of the connection between the polygonal tubular structure and the support plate are rounded; and the support plate is provided with at least one set of energy absorption ribs connected to the lower part of the polygonal tubular structure.

[0007] Furthermore, the polygonal cylindrical structure is formed by four sides extending and enclosing along the third direction, and is made of aluminum alloy material, such as 6082 aluminum alloy, and is extruded by a mold to form a hollow cylindrical structure.

[0008] Furthermore, two groups of energy absorbing ribs connected to the lower part of the polygonal cylindrical structure are provided on the support plate. The two energy absorbing ribs are distributed along the first direction and are not connected to each other. The two energy absorbing ribs are respectively located on both sides of the polygonal cylindrical structure.

[0009] Furthermore, a mold is provided for molding a crash box at the rear of an automobile, comprising an upper mold mechanism and a lower mold mechanism;

[0010] The upper die mechanism includes an upper plate, an upper die, a guide sleeve, an upper die punch, and a nitrogen cylinder. The upper die punch is mounted on the lower surface of the upper plate through an upper die fixing member. Guide sleeves are respectively mounted at the four corners of the lower surface of the upper plate. A plurality of nitrogen cylinders uniformly distributed in a circular shape are provided on the lower surface of the upper plate. The telescopic ends of the nitrogen cylinders are respectively connected to the upper die. The upper die is provided with a first cavity that is movably matched with the upper die punch.

[0011] The lower mold mechanism includes a lower pad, a lower mold, and guide pillars. The upper surface of the lower pad is equipped with a lower mold that cooperates with the upper mold for forming the energy absorption box. A number of heating holes that are inclined upward and correspond to the rounded corners of the energy absorption box are opened on the outer circumference of the lower mold. Guide pillars corresponding to the guide sleeves are respectively installed at the four corners of the upper surface of the lower pad.

[0012] Furthermore, the lower mold is provided with a second cavity distributed along the third direction and used for forming the energy absorption box, and the upper portion of the inner wall of the second cavity is provided with a step surrounding the inner wall.

[0013] Furthermore, the lower mold is movably provided with a material stripping body tangent to the inner wall of the second cavity, the lower plate is provided with a lower mold fixing block, and the center of the lower mold fixing block is provided with a material stripping guide hole distributed along the third direction.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The automobile rear energy absorption box disclosed by the present invention improves the integrity and reliability of the structure, avoids the complicated process of manufacturing and reassembling multiple components separately, thereby shortening the manufacturing cycle and improving production efficiency; the mold used for forming the automobile rear energy absorption box can realize local heating of the mold, so that various parts of the energy absorption box are heated evenly during the forming process, which helps to solve the stress concentration problem caused by different material flow rates and reduce the risk of product cracking. By adopting differential temperature forging, local heating is performed on the difficult-to-form parts of the parts during the production process. By using heating tubes of different powers, corresponding allocation is made to the difficult-to-form parts, and the difficult-to-form parts of the product are locally heated to accelerate the material flow in these parts. In actual production, the forging tonnage can be reduced to less than 1,200 tons, greatly improving processing efficiency and reducing processing difficulty; and because the height of the product is high, there is insufficient space for material withdrawal after forming. By making the mold into a split structure, the upper mold is pressed by a nitrogen cylinder when the mold is closed to ensure that the upper and lower molds are tightly closed, and the blank is extruded by the upper mold punch to form. This design shortens the material withdrawal stroke by at least 70 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the existing energy absorption box disclosed in the background technology of the present invention;

[0017] Figure 2 This is a schematic diagram of the product structure of an embodiment of the present invention;

[0018] Figure 3 This is a schematic diagram of the product structure of an embodiment of the present invention;

[0019] Figure 4 This is a schematic diagram of the mold structure of an embodiment of the present invention;

[0020] Figure 5 This is a schematic cross-sectional structural diagram of a mold portion according to an embodiment of the present invention;

[0021] Figure 6 This is a schematic cross-sectional view of a mold according to an embodiment of the present invention;

[0022] Figure 7 This is a schematic diagram of the cross-sectional structure of the upper mold and lower mold matching according to an embodiment of the present invention;

[0023] Figure 8 For the embodiment of the present invention Figure 7 An enlarged schematic diagram of the cross-sectional structure of the middle part;

[0024] Figure 9 Schematic diagram of the upper and lower mold matching structure of the mold according to the embodiment of the present invention;

[0025] Figure 10 This is a schematic diagram of the upper die punch structure of an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following detailed description of the embodiments of the technical solution of this application is provided in conjunction with the accompanying drawings. The following embodiments and drawings are intended only to more clearly illustrate the technical solution of this application and are therefore provided as examples only and are not intended to limit the scope of protection of this application. The accompanying drawings schematically illustrate only the parts relevant to the technical solution of this application and do not represent the actual structure of the product.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0028] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are used only to distinguish different objects and should not be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), similarly, "multiple groups" refers to more than two (including two), and "multiple pieces" refers to more than two (including two).

[0029] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0030] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0031] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application.

[0032] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0033] As one of the main safety parts of a car, the main function of the energy absorption box is to transfer the force borne by the anti-collision beam to the longitudinal beam, while absorbing part of the energy generated during the collision to protect the passenger compartment. This function is usually guaranteed by its own large impact deformation. In other words, the energy absorption box deforms and collapses during the impact, absorbing the kinetic energy brought by the impact end, thereby reducing the energy transmitted to the rear end. Most of the energy absorption boxes of new energy vehicles currently on the market are composed of stamped parts or castings through bolts and welding (such as Figure 1 ), this type of new energy vehicle energy absorption box product has many components, a long manufacturing cycle, and low production efficiency.

[0034] Based on this, it is currently proposed to form the energy absorption box of new energy vehicles in one piece through extrusion forging, which can reduce the number of parts and shorten the manufacturing cycle. However, the existing energy absorption box of new energy vehicles requires higher strength and performance without destroying the organizational streamline of the material. Moreover, due to the high height of the energy absorption box product of new energy vehicles, it is not convenient to withdraw the material. Moreover, because the product is a thin-walled special-shaped structural part, during production, the material flow rate of each part in the mold cavity is different, the stress is easy to concentrate, and the product is easy to crack during the extrusion process, making forging difficult.

[0035] In a specific embodiment of the present invention, the first direction is along the X direction in the figure, the second direction is along the Y direction in the figure, and the third direction is along the Z direction in the figure.

[0036] In this embodiment, in the first aspect, a car rear energy absorption box includes a support plate 10, the support plate 10 is provided with a polygonal cylindrical structure 20 extending along the third direction and having rounded corners at the inner and outer sides of each connection, the outer side of the connection between the polygonal cylindrical structure 20 and the support plate 10 is rounded, and the support plate 10 is provided with at least one group of energy absorbing ribs 30 connected to the lower part of the polygonal cylindrical structure 20, through the rounded corners at the inner and outer sides of each connection of the polygonal cylindrical structure 20, and the support plate 10 is provided with energy absorbing ribs 30, the energy absorbing ribs 30 and the polygonal cylindrical structure 20 The outer side walls are connected to achieve an one-piece molding design. This structural design helps to better absorb energy through structural deformation and collapse during a collision, thereby improving the energy absorption effect of the energy absorption box and protecting the passenger compartment. Moreover, it is formed in one piece through extrusion forging. Compared with the existing energy absorption boxes on the market which are composed of stamped parts or castings through bolts and welding, it can streamline the number of parts, reduce the connection links between parts, improve the integrity and reliability of the structure, avoid the complicated process of manufacturing and reassembling multiple parts separately, thereby shortening the manufacturing cycle and improving production efficiency.

[0037] In one or more possible embodiments of the present invention, the polygonal cylindrical structure 20 is formed by four sides extending and enclosing along a third direction, and is made of aluminum alloy material, such as 6082 aluminum alloy, and is extruded by a mold to form a hollow cylindrical structure. The aluminum alloy has high strength and good toughness, and can reduce the overall weight of the car while ensuring the strength of the energy absorption box, thereby improving the endurance of new energy vehicles.

[0038] In one or more possible embodiments of the present invention, two groups of energy-absorbing ribs 30 connected to the lower part of the polygonal cylindrical structure 20 are provided on the support plate 10, and the two energy-absorbing ribs 30 are distributed along the first direction, and the two energy-absorbing ribs 30 are not connected to each other. The two energy-absorbing ribs 30 are respectively located on both sides of the polygonal cylindrical structure 20.

[0039] In conjunction with the accompanying drawings, the present invention discloses a car rear energy absorption box, wherein a support plate 10 of the car rear energy absorption box is provided with a four-sided cylindrical structure and two sets of energy absorption ribs 30, which are respectively provided on two opposite outer side walls of the four-sided cylindrical structure. The support plate 10 and the four-sided cylindrical structure are integrally formed, so that the support plate 10 is a plate-shaped structure with a square hole. The connection between the support plate 10 and the four-sided cylindrical structure is rounded, and the support plate 10 can be formed with a plurality of protrusions for processing mounting holes (see Figure 2 In this embodiment, the rear crash box has a wall thickness of 4mm and an overall height of 310mm. Each side of the four-sided cylindrical structure is 110mm long. Using 6082 aluminum alloy, it is integrally formed by extrusion forging using existing techniques. Using Deform forming analysis software, it is determined that the forging tonnage required is over 3,000 tons, making the overall forming process quite challenging. Based on this, the present invention also provides a mold for forming the rear crash box.

[0040] In a second aspect, a mold is provided for molding a crash box at the rear of an automobile, comprising an upper mold mechanism 100 and a lower mold mechanism 200;

[0041] The upper die mechanism 100 includes an upper plate 110, an upper die 120, a guide sleeve 130, an upper die punch 140, and a nitrogen cylinder 150. The upper die punch 140 is mounted on the lower surface of the upper plate 110 through the upper die 120 fixing member. The guide sleeves 130 are respectively mounted at the four corners of the lower surface of the upper plate 110. The lower surface of the upper plate 110 is provided with a plurality of circular and evenly distributed nitrogen cylinders 150. The telescopic ends of each of the nitrogen cylinders 150 are respectively connected to the upper die 120. The upper die 120 is provided with a first cavity 121 that is movably matched with the upper die punch 140.

[0042] The lower mold mechanism 200 includes a lower pad 210, a lower mold 220, and a guide column 230. The upper surface of the lower pad 210 is equipped with a lower mold 220 that cooperates with the upper mold 120 for forming the energy absorption box. The lower mold 220 is provided with a second cavity 221 distributed along a third direction and used to form the energy absorption box. A plurality of heating holes 240 that are inclined upward and correspond to the vertical corners of the energy absorption box are provided on the outer circumference of the lower mold 220. Guide columns 230 corresponding to the guide sleeves 130 are respectively installed at the four corners of the upper surface of the lower pad 210.

[0043] In the specific implementation of the present invention, the upper die punch 140 in the upper die mechanism 100 is movably matched with the first die cavity 121 of the upper die 120, and the lower die 220 in the lower die mechanism 200 is provided with a second die cavity 221 for forming the energy absorption box. The outer circumference of the lower die 220 is provided with a plurality of heating holes 240 that are inclined upward and correspond to the fillets of the energy absorption box. By arranging a heating tube in each heating hole 240, the temperature of the heating tube is controllable, so that the mold can be locally heated, so that each part of the energy absorption box is heated evenly during the forming process, which helps to solve the stress concentration problem caused by different material flow rates and reduce the risk of product cracking. By adopting differential temperature forging In the manufacturing process, local heating is performed on the parts that are difficult to form. Heating tubes with different powers are used and distributed accordingly for the parts that are difficult to form. Local heating is performed on the parts that are difficult to form, which accelerates the material flow in these parts. In actual production, various optimizations are used to reduce the tonnage to less than 1,200 tons, which greatly improves the processing efficiency and reduces the processing difficulty. Moreover, due to the high height of the product, there is insufficient space for material withdrawal after forming. The mold is made into a split structure, and the upper mold 120 is pressed by the nitrogen cylinder 150 when the mold is closed to ensure that the upper mold 120 and the lower mold 220 are tightly closed. The blank is extruded and formed by the upper mold punch 140. This design shortens the material withdrawal stroke by at least 70 mm.

[0044] In one or more possible embodiments of the present invention, a structure of an upper die punch 140 and a lower die 220 is provided to realize the production of the above-mentioned product. Specifically, the upper die punch 140 includes a first part 141 connected to the upper pad 110, and the bottom end of the first part 141 is connected to a second part 142 for extruding the blank. In this embodiment, the second part 142 is a tetrahedron with rounded corners. The second part 142 is rounded at the connection between the first part 141 and the second part 142. The second part 142 corresponds to each side wall of the lower die 220 opening of the lower die 220. Accordingly, the second cavity 221 of the lower die 220 corresponds to the shape of the outer wall of the product to be processed and formed. The outer side wall of the lower die opening set on the lower die 220 is tangent to the inner wall of the first cavity 121 of the upper die 120, and the lower die opening is used to form the upper pad 10 and the reinforcing rib 30.

[0045] In one or more possible embodiments of the present invention, a step 2211 surrounding the inner wall is provided on the upper part of the inner wall of the second cavity 221, and the mouth of the lower mold 220 of the second cavity 221 of the lower mold 220 is designed to be stepped, which can reduce the friction between the blank and the side wall of the mold after forming, and facilitate material removal.

[0046] In one or more possible embodiments of the present invention, the lower mold 220 is movably provided with a material withdrawal body 250 tangent to the inner wall of the second cavity 221, and the lower plate 210 is provided with a lower mold fixing block 260. The center of the lower mold fixing block 260 is provided with a material withdrawal guide hole 261 distributed along a third direction. This material withdrawal structure design facilitates the removal of the energy absorption box from the mold after it is formed, thereby solving the problem that the energy absorption box product of new energy vehicles is high and inconvenient for material withdrawal.

[0047] In one or more possible embodiments of the present invention, the lower surface of the upper pad 110 is further provided with a plurality of groups of evenly circumferentially arranged fixing bolts 160 . The lower portion of each fixing bolt 160 is movably connected to the upper mold 120 , and cooperates with the nitrogen cylinder 150 to facilitate position adjustment of the upper mold 120 .

[0048] A method for manufacturing a rear energy absorption box of an automobile comprises the following steps:

[0049] (1) Mold installation and preparation: Install and debug the upper mold mechanism 100 and the lower mold mechanism 200, ensure that the guide sleeves 130 at the four corners of the lower surface of the upper pad 110 and the guide pillars 230 at the four corners of the upper surface of the lower pad 210 can accurately match, so that the upper mold 120 and the lower mold 220 can be accurately aligned when the mold is closed. At the same time, check whether the nitrogen cylinder 150 can work normally and prepare the aluminum alloy material to be processed (such as 6082 aluminum alloy);

[0050] (2) Heating the mold: The mold is heated to the forging process temperature by an electric heating ring or a flame. The heating holes 240 on the outer circumference of the lower mold 220 heat the lower mold 220 to make the mold reach a suitable working temperature. In particular, it is necessary to ensure that the corners of the energy absorption box and other parts prone to stress concentration are heated evenly to improve the fluidity of the material in the mold cavity. The four heating holes on the lower mold are used to achieve the highlight of differential temperature forging. They are not used to heat the entire mold. The mold heating is a separate heating ring. The temperature of these parts is increased to prevent the material from flowing easily at the four corners of the part. During production, the temperature of these four corners of the mold is always high, the material flows well, the molding tonnage can be reduced, and the mold loss can be reduced. This is the highlight of the process disclosed by the present invention. In the specific implementation, the mold is heated to 200 degrees and locally heated to 250 degrees.

[0051] (3) Placing the material: The aluminum alloy material is placed in the second cavity 221 of the lower mold 220. The material should be placed flat to ensure that it can evenly fill the cavity under the action of the mold;

[0052] (4) Die closing and extrusion: Start the upper die mechanism 100, and the upper die punch 140 moves downward under the action of the nitrogen cylinder 150, enters the first cavity 121 of the upper die 120, and cooperates with the lower die 220 to extrude the aluminum alloy material placed in the second cavity 221 of the lower die 220. During the extrusion process, the material gradually flows under the action of the die, filling various parts of the second cavity 221 to form a polygonal cylindrical structure 20 and a support plate 10. At the same time, the energy absorbing ribs 30 are also formed at the corresponding positions. Due to the precise design of the die, the forming accuracy of the energy absorbing box can be guaranteed;

[0053] (5) Pressure holding and cooling: After the extrusion is completed, a certain pressure is maintained for a period of time to allow the formed energy absorption box to cool and shape in the mold to ensure the stability of its shape and size;

[0054] (6) Material removal: After cooling is completed, the material is removed through the material removal body 250 and the material removal guide hole 261. The material removal body 250 is tangent to the inner wall of the second cavity 221. Under a certain external force, the formed automobile rear energy absorption box is pushed out of the mold to complete the entire manufacturing process.

[0055] The specific embodiments disclosed in the present invention fall within the scope of protection of the claims of the present invention, and are the specific lower implementation scope of the characteristic part of the present invention. The protection content of the specific embodiments is merely an explanation of the protection scope of the claims of the present invention. The protection scope of the present invention is not limited to the protection content of the specific embodiments, and the protection content of the specific embodiments should not be understood as a limitation on the protection scope of the claims of the present invention.

[0056] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the scope of the present invention. Therefore, the above description is illustrative in nature and should not be construed as limiting the scope of the claims.

[0057] Unless otherwise defined, all academic and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0058] In case of conflict, the definitions in this specification shall prevail.

[0059] The use of "a" and "an / kind" to describe elements of the present invention is only for convenience and to give a general view of the present invention. Unless otherwise clearly stated, the description should be understood to include one / kind or at least one / kind.

Claims

1. A car rear energy absorption box, characterized by: The invention comprises a support plate (10), wherein the support plate (10) is provided with a polygonal cylindrical structure (20) extending along a third direction and having rounded corners at the inner and outer sides of each connection; the outer sides of the connection between the polygonal cylindrical structure (20) and the support plate (10) are rounded; and the support plate (10) is provided with at least one group of energy absorbing ribs (30) connected to the lower part of the polygonal cylindrical structure (20).

2. The automobile rear crash box according to claim 1, characterized in that: The polygonal cylindrical structure (20) is formed by four sides extending and enclosing along a third direction, and is extruded by a mold to form a hollow cylindrical structure.

3. The automobile rear crash box according to claim 1, characterized in that: The support plate (10) is provided with two groups of energy-absorbing ribs (30) connected to the lower portion of the polygonal cylindrical structure (20); the two energy-absorbing ribs (30) are distributed along a first direction, the two energy-absorbing ribs (30) are not connected to each other, and the two energy-absorbing ribs (30) are respectively located on both sides of the polygonal cylindrical structure (20).

4. A mold, characterized in that: Used for forming an automobile rear energy absorption box, comprising an upper mold (120) mechanism (100) and a lower mold (220) mechanism (200); The upper die (120) mechanism (100) comprises an upper plate (110), an upper die (120), a guide sleeve (130), an upper die punch (140), and a nitrogen cylinder (150); the upper die punch (140) is mounted on the lower surface of the upper plate (110) through an upper die (120) fixing member; the guide sleeves (130) are respectively mounted at the four corners of the lower surface of the upper plate (110); the lower surface of the upper plate (110) is provided with a plurality of nitrogen cylinders (150) uniformly distributed in a circular shape; the telescopic ends of the nitrogen cylinders (150) are respectively connected to the upper die (120); the upper die (120) is provided with a first cavity (121) that is movably matched with the upper die punch (140); The lower die (220) mechanism (200) comprises a lower plate (210), a lower die (220), and a guide column (230); the upper surface of the lower plate (210) is provided with a lower die (220) for cooperating with the upper die (120) for forming the energy absorption box; the lower die (220) is provided with a second die cavity (221) distributed along a third direction and used for forming the energy absorption box; a plurality of upwardly inclined heating holes (240) corresponding to the vertical corners of the energy absorption box are provided on the outer circumference of the lower die (220); and the four corners of the upper surface of the lower plate (210) are respectively provided with guide columns (230) corresponding to the guide sleeves (130):.

5. A mold according to claim 4, characterized in that: The upper die punch (140) comprises a first portion (141) connected to the upper pad (110), and a second portion (142) for extruding the blank is connected to the bottom end of the first portion (141).

6. A mold according to claim 4, characterized in that: The upper portion of the inner wall of the second cavity (221) is provided with a step (2211) surrounding the inner wall.

7. A mold according to claim 4, characterized in that: The lower die (220) is movably provided with a material stripping body (250) tangent to the inner wall of the second die cavity (221); a lower die fixing block (260) is mounted on the lower pad (210); and a material stripping guide hole (261) distributed along a third direction is provided at the center of the lower die fixing block (260).

8. A mold according to claim 4, characterized in that: The lower surface of the upper pad (110) is also provided with a plurality of groups of evenly arranged fixing bolts (160), and the lower portion of each fixing bolt (160) is movably connected to the upper mold (120).

9. A method for manufacturing a rear crash box of an automobile, characterized in that: The following steps are included: (1) Installation and preparation of the mold: Install and debug the upper mold (120) mechanism (100) and the lower mold (220) mechanism (200), ensure that the guide sleeves (130) at the four corners of the lower surface of the upper pad (110) and the guide pillars (230) at the four corners of the upper surface of the lower pad (210) can accurately correspond to each other, so that the upper mold (120) and the lower mold (220) can be accurately aligned when the mold is closed. At the same time, check whether the nitrogen cylinder (150) can work normally and prepare the aluminum alloy material to be processed; (2) Heating the mold: The mold is heated to the forging process temperature by an electric heating ring or a flame, and the heating holes (240) on the outer circumference of the lower mold (220) heat the lower mold (220) so that the mold reaches a suitable working temperature. In particular, it is necessary to ensure that the corners of the energy absorption box where stress concentration is likely to occur are heated evenly to improve the fluidity of the material in the mold cavity; (3) Placing the material: placing the aluminum alloy material in the second cavity (221) of the lower mold (220). The material should be placed flat to ensure that it can evenly fill the cavity under the action of the mold; (4) Die closing and extrusion: the upper die (120) mechanism (100) is started, and the upper die punch (140) moves downward under the action of the nitrogen cylinder (150), enters the first die cavity (121) of the upper die (120), and cooperates with the lower die (220) to extrude the aluminum alloy material placed in the second die cavity (221) of the lower die (220). During the extrusion process, the material gradually flows under the action of the die, filling various parts of the second die cavity (221) to form a polygonal cylindrical structure (20) and a support plate (10). At the same time, the energy absorbing ribs (30) are also formed at corresponding positions; (5) Pressure-maintaining cooling: After the extrusion is completed, a certain pressure is maintained for a period of time to allow the formed energy absorption box to cool and shape in the mold to ensure the stability of its shape and size; (6) Material removal: After cooling is completed, the material is removed through the material removal body (250) and the material removal guide hole (261). The material removal body (250) is tangent to the inner wall of the second cavity (221). Under a certain external force, the formed automobile rear energy absorption box is pushed out of the mold to complete the entire manufacturing process.

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