A method for manufacturing a lightweight bumper

Abstract

The application provides a light bumper manufacturing method, and belongs to the technical field of bumpers. The method comprises the following steps: a rectangular straight pipe manufacturing step of processing a first positioning hole on a rectangular straight pipe; a support box manufacturing step of welding corrugated plates on both ends of a cylindrical support piece to form a support box, and processing a second positioning hole on the support box; a main beam blank manufacturing step of connecting the rectangular straight pipe and the support box; a bending forming step of bending the main beam blank into an arched beam; and a hot gas expansion forming step of processing the arched beam into a required bumper through a hot gas expansion forming process. The method increases the support strength by means of spot welding connection of the support box, has relatively low precision requirements, is simpler in process, and is low in cost. The bumper manufactured by the method can further realize light weight by increasing a reinforcing rib structure penetrating through the whole bumper, increasing the strength of the support box structure in a place with high strength requirement, and increasing the overall strength in a manner of increasing an inner recess rib on the surface.

Description

Technical Field

[0001] This application belongs to the field of bumper technology, and more specifically, relates to a method for manufacturing a lightweight bumper. Background Technology

[0002] Car bumpers absorb and mitigate external impacts, protecting the vehicle body and improving its aerodynamics; they are considered safety components. When a bumper is hit, it absorbs the impact energy and undergoes plastic deformation to reduce energy transfer.

[0003] Metal materials, such as steel, are commonly used in car bumpers. They have strong load-bearing capacity and good impact resistance. However, steel has a high density, which is not conducive to weight reduction. Chinese invention patent CN110576292B (publication date: 2022.05.06) discloses a method for manufacturing a car bumper. It obtains a H-shaped tube profile by welding a rectangular straight tube and a C-shaped profile. The short side where the two meet becomes the central reinforcing rib of the H-shaped tube profile, which simplifies the manufacturing process while achieving weight reduction. However, the bumper obtained by this method is made by welding two main bodies, a rectangular straight tube and a C-shaped profile. The welding distance is long, and the connection accuracy requirement is high, which affects the simplification of the process. Summary of the Invention

[0004] On the one hand, the present invention provides a method for manufacturing a lightweight bumper, which can produce a bumper with a lightweight structure while ensuring the strength of the bumper.

[0005] To achieve the above objectives, the technical solution adopted in this application is: to provide a method for manufacturing a lightweight bumper, comprising:

[0006] Steps for making a rectangular straight tube: Make a rectangular straight tube and make two sets of first positioning holes through the side wall of the rectangular straight tube. The two sets of first positioning holes are symmetrically arranged along the extension direction of the rectangular straight tube.

[0007] Support box manufacturing steps: Weld corrugated plates to both ends of the cylindrical support to form a support box, and make a second positioning hole through the corrugated plates at both ends on the support box;

[0008] Main beam blank fabrication steps: Place two sets of support boxes into the rectangular straight tube. Align the second positioning holes on the two sets of support boxes with the two sets of first positioning holes on the rectangular straight tube. The corrugated plates at both ends of the support boxes support and abut against the inner sidewall of the rectangular straight tube. Spot weld the support boxes to the rectangular straight tube at the first and second positioning holes to fix them, so that the rectangular straight tube and the support boxes are combined to form a main beam blank with local reinforcement at the support boxes.

[0009] Bending and forming steps: The main beam blank is bent near both ends to form an arched beam. The arched beam consists of a middle pre-forming section, a bending pre-forming section, and an end pre-forming section from the middle to both ends. The support box is located in the middle pre-forming section.

[0010] Hot gas expansion forming steps: The arched beam is processed into the main body of the beam using the hot gas expansion forming process. The middle pre-forming section is formed into the middle section, the bending pre-forming section is formed into the bending section, and the end pre-forming section is formed into the end section. In the middle section, concave ribs are distributed on the outer wall facing and away from the bending direction of the bending section. After the main body of the beam is cooled, the required bumper is obtained.

[0011] Optionally, in the rectangular straight tube manufacturing step, a round tube is made into a rectangular straight tube by continuous rolling or a steel coil is made into a rectangular straight tube by a combination of cutting and continuous rolling and welding.

[0012] Optionally, for the hot gas expansion forming process in the hot gas expansion forming step, the formed part of the arch beam after heating is realized by a hot gas expansion forming mold;

[0013] The hot air expansion forming mold includes a hot air expansion upper mold, a hot air expansion lower mold, a high-pressure air source, air pipes, two sets of sealing pushers, and two sets of hydraulic cylinders. The hot air expansion lower mold has a lower groove that matches the arched beam, and the hot air expansion upper mold has a lower protrusion that matches the arched beam. The lower groove and the lower protrusion are arranged opposite to each other. The two sets of sealing pushers are connected to the high-pressure air source through air pipes, and the two sets of hydraulic cylinders are connected to the two sets of sealing pushers. Both the lower groove and the lower protrusion include a middle forming section, a bending forming section, and an end forming section arranged from the middle to both ends, respectively, to correspond to the middle section, bending section, and end section on the beam body. The bottom wall of the lower groove located in the middle forming section and the top arm of the lower protrusion located in the middle forming section are both provided with protruding ribs.

[0014] In the hot gas expansion forming step, the two sets of sealing pushers are respectively connected to the ends of the two end pre-forming sections; after the arch beam is compressed and expanded, its sidewalls fit with the inner sidewalls of the lower groove and the lower convex groove, and the part of the arch beam that contacts the convex rib forms an inner concave rib.

[0015] Optionally, the sidewall of the middle forming section is provided with a sealing protrusion that inserts into the first positioning hole.

[0016] Optionally, a pressing step is provided between the bending forming step and the hot air expansion forming step;

[0017] Pressing step: Press the two ends of the arch beam together to form a shape, so that the cross-sectional shape of the end preformed section away from the bent preformed section gradually transitions from rectangular to circular.

[0018] In the hot air expansion forming step, the circular end section of the pre-formed end section is connected to the sealing pusher; after the main beam cools, the part of the end section whose cross-sectional shape gradually transitions from rectangular to circular is cut off to obtain the required bumper.

[0019] Optionally, in the pressing step, the pressing and forming of both ends of the arch beam is achieved by pressing mold;

[0020] The pressing mold includes an upper pressing mold, a lower pressing mold, and a cylindrical mandrel. Both the upper pressing mold and the lower pressing mold have corresponding pressing half-grooves. The pressing half-grooves on the upper pressing mold and the pressing half-grooves on the lower pressing mold combine to form a pressing groove that transitions from a rectangle at one end to a circle at the other end.

[0021] In the pressing step, the mandrel is inserted into the end of the preformed section away from the bending preformed section, and then the end of the preformed section away from the bending preformed section is placed into the pressing half groove of the lower pressing mold. The upper pressing mold and the lower pressing mold are then closed to press the end of the arch beam into shape.

[0022] Optionally, in the manufacturing process of the rectangular straight tube, the material of the rectangular straight tube is BR1500HS, and the wall thickness of the rectangular straight tube ranges from 1.8 to 2.5 mm.

[0023] In the hot gas expansion forming step, the heating temperature range of the arch beam is 900-1000℃, and the hot gas expansion pressure range is 28-32MPa.

[0024] On the other hand, the present invention provides a bumper that achieves lightweighting while ensuring strength.

[0025] To achieve the above objectives, the technical solution adopted in this application is as follows: a bumper is provided, including an arched body and two support boxes; the cross-section of the arched body is a hollow rectangle, and the arched body includes a middle section, a bent section and an end section arranged sequentially from the middle to both ends; each support box includes a cylindrical support member and corrugated plates welded to both ends of the support member.

[0026] Two support boxes are symmetrically installed in the middle section. The inner wall of the middle section is supported by a corrugated plate. The outer walls of the middle section facing and away from the bending direction of the bending section are all equipped with concave ribs.

[0027] Optionally, the side wall of the middle section is provided with two sets of first positioning holes, and the support box is provided with second positioning holes that penetrate the two corrugated plates. The two sets of first positioning holes are respectively aligned with the second positioning holes on the two support boxes; the concave ribs aligned with the corrugated plates are placed in the recesses on the surface of the corrugated plates.

[0028] Optionally, the sidewalls of the arched main body are provided with weight-reducing holes.

[0029] The advantages of the technical solution in this application compared to the prior art are as follows:

[0030] This lightweight bumper manufacturing method increases support strength by spot-welding the support box together. Compared to continuously welding two main components over a long distance, this method requires lower precision, simplifies the process, and is less expensive. Furthermore, instead of adding a reinforcing rib structure that runs the entire length of the bumper, increasing strength only near the bending points where strength requirements are high, and adding concave ribs to the surface to improve overall strength, further reduces weight and achieves lightweight design. The first and second positioning holes facilitate positioning between the rectangular straight tube and the support box and enable spot welding connections. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of a rectangular straight tube structure;

[0033] Figure 2 This is a schematic diagram of the support box structure;

[0034] Figure 3 A structural sectional view of the main beam blank located at the support box;

[0035] Figure 4 This is a schematic diagram of the arched beam structure before the pressing step;

[0036] Figure 5 This is a schematic diagram of the arch beam structure after the pressing step;

[0037] Figure 6 This is a schematic diagram of the pressing mold structure;

[0038] Figure 7 for Figure 6 Enlarged view of a portion of point A in the middle;

[0039] Figure 8 This is a schematic diagram of the main beam structure;

[0040] Figure 9 This is a schematic diagram of the bumper structure;

[0041] Figure 10 This is a schematic diagram of a hot air expansion forming mold structure;

[0042] Figure 11 This is a schematic diagram of the hot air expansion upper mold structure;

[0043] Figure 12 for Figure 11 Enlarged view of a section at point B in the middle;

[0044] Figure 13 for Figure 8 Enlarged view of a section at point C;

[0045] Figure 14 This is a cross-sectional view of the bumper at the support box.

[0046] Icons: 10. Rectangular straight tube; 11. First positioning hole; 20. Support box; 21. Support component; 22. Corrugated plate; 23. Second positioning hole; 30. Main beam blank; 40. Arch beam; 41. Middle preformed section; 42. Bending preformed section; 43. End preformed section; 50. Beam body; 51. Middle section; 52. Bending section; 53. End section; 54. Concave rib; 55. Weight reduction hole;

[0047] 100. Hot air expansion forming mold; 101. Hot air expansion upper mold; 102. Hot air expansion lower mold; 103. High-pressure air source; 104. Air pipe; 105. Sealing pusher; 106. Hydraulic cylinder; 107. Lower groove; 108. Lower protrusion; 109. Middle forming section; 110. Bending forming section; 111. End forming section; 112. Rib; 113. Sealing protrusion;

[0048] 200. Pressing mold; 201. Upper pressing mold; 202. Lower pressing mold; 203. Mandrel; 204. Pressing half groove; 205. Pressing groove; 206. Positioning boss. Detailed Implementation

[0049] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0050] It should be noted that when a component is referred to as being "fixed" or "set" to another component, it can be directly or indirectly attached to that other component. When a component is referred to as being "connected" to another component, it can be directly or indirectly connected to that other component.

[0051] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0053] Example 1:

[0054] This embodiment provides a method for manufacturing a lightweight bumper, including:

[0055] S1, Steps for fabricating a rectangular straight tube: Based on Figure 1 As shown, a rectangular straight tube 10 is fabricated, and two sets of first positioning holes 11 are opened through the side wall of the rectangular straight tube 10. The two sets of first positioning holes 11 are symmetrically arranged along the extension direction of the rectangular straight tube 10.

[0056] In the above-described rectangular straight tube manufacturing steps, a round tube can be formed into a rectangular straight tube 10 by continuous rolling, or a steel coil can be formed into a rectangular straight tube 10 by a combination of cutting and continuous rolling and welding. The continuous rolling operation is achieved by a roll forming machine.

[0057] In this embodiment, the rectangular straight tube 10 is made of BR1500HS, a high-strength steel suitable for various automotive applications requiring high strength and good formability. The rectangular straight tube 10 has a wall thickness of 2mm, achieving lightweighting while maintaining strength. Of course, in other embodiments, depending on the vehicle being applied, the wall thickness of the rectangular straight tube 10 can also be 1.8mm, 2.5mm, or other dimensions between 1.8mm and 2.5mm.

[0058] S2, Support box fabrication steps: Based on Figure 2 As shown, corrugated plates 22 are welded to both ends of the cylindrical support member 21 to form a support box 20, and second positioning holes 23 are opened on the support box 20, penetrating the corrugated plates 22 at both ends. The height of the support box 20 is the same as the internal height of the rectangular straight tube 10, and the width of the support box 20 is the same as the internal width of the rectangular straight tube 10, so that the support box 20 can be placed inside the rectangular straight tube 10.

[0059] S3, Main beam blank fabrication steps: Based on Figure 3 As shown, two sets of support boxes 20 are inserted into the rectangular straight tube 10 from the ends. The second positioning holes 23 on the two sets of support boxes 20 are aligned with the two sets of first positioning holes 11 on the rectangular straight tube 10, respectively. The corrugated plates 22 at both ends of the support boxes 20 support and abut against the inner sidewall of the rectangular straight tube 10. The support boxes 20 are spot-welded to the rectangular straight tube 10 at the first positioning holes 11 and the second positioning holes 23, so that the rectangular straight tube 10 and the support boxes 20 are combined to form a main beam blank 30 with local reinforcement at the support boxes 20.

[0060] On the final bumper, the area where the support box 20 is located requires higher strength, while other areas require lower strength. Therefore, support boxes 20 are installed at the corresponding locations for support. Based on... Figure 3 As shown, the left and right edges of the corrugated plate 22 can be bent to fit against the corner of the inner side of the rectangular straight tube 10, so as to ensure the support strength.

[0061] S4, Bending and forming steps: Based on Figure 4 As shown, the main beam blank 30 is bent near both ends to form an arched beam 40. The bending operation can be achieved using a pipe bending machine or by pressure bending. After the bending forming step is completed, the arched beam 40 forms a middle pre-forming section 41, a bent pre-forming section 42, and an end pre-forming section 43 from the middle to both ends, with the support box 20 located within the middle pre-forming section 41.

[0062] S5, lamination step: based on Figure 5 As shown, the two ends of the arch beam 40 are pressed together to form a shape, so that the cross-sectional shape of the end preformed section 43 away from the bending preformed section 42 gradually transitions from rectangular to circular.

[0063] The pressing step, as a transitional step, is placed between the bending and hot-air forming steps to round the two ends of the arch beam 40. Since the arch beam 40 needs to dock with the sealing pusher 105 in the subsequent hot-air forming step, and the circular cross-section can effectively achieve a seal when in contact with the sealing pusher 105, the two ends of the arch beam 40 are rounded.

[0064] In the pressing step, the pressing and forming of both ends of the arched beam 40 is achieved using a pressing mold 200. Specifically, based on... Figure 6 and Figure 7As shown, the pressing mold 200 includes an upper pressing mold 201, a lower pressing mold 202, and a cylindrical mandrel 203. Both the upper pressing mold 201 and the lower pressing mold 202 have corresponding pressing half-grooves 204. The pressing half-grooves 204 on the upper pressing mold 201 and the lower pressing mold 202 combine to form a pressing groove 205 that transitions from a rectangle at one end to a circle at the other. In the pressing step, the mandrel 203 is inserted into the end of the pre-formed section 43 away from the bent pre-formed section 42 to provide support for the pre-formed section 43 and control the wall thickness of the cross-section at the port. Then, the end of the pre-formed section 43 away from the bent pre-formed section 42 is placed into the pressing half-groove 204 of the lower pressing mold 202. The upper pressing mold 201 and the lower pressing mold 202 close to press and form the end of the arched beam 40. The end of the preformed section 43 away from the bending preformed section 42 is formed into a shape that gradually transitions from rectangular to circular under the extrusion of the two pressing half-grooves 204. At the same time, in order to achieve axial limiting, a positioning boss 206 is provided on the inner sidewall of the pressing half-grooves 204, and the positioning boss 206 abuts against the end of the preformed section 43.

[0065] S6, Hot Air Inflation Forming Step: Based on Figure 5 , Figure 8 and Figure 9 As shown, the arched beam 40 is processed into the main beam 50 using a hot gas expansion forming process. The middle pre-formed section 41 corresponds to the middle section 51, the bending pre-formed section 42 corresponds to the bending section 52, and the end pre-formed section 43 corresponds to the end section 53. In the middle section 51, concave ribs 54 are distributed on the outer wall facing and away from the bending direction of the bending section 52. After the main beam 50 cools, the portion of the end section 53 whose cross-sectional shape gradually transitions from rectangular to circular is removed to obtain the desired bumper.

[0066] In this embodiment, for BR1500HS material and 2mm wall thickness, the preferred heating temperature for the arch beam 40 is 950℃, and the preferred hot gas pressure is 20MPa. Of course, temperatures within a certain range, such as 900℃, 1000℃, or temperatures between 900 and 1000℃, and pressures within a certain range, such as 28MPa, 32MPa, or pressures between 28 and 32MPa, can all meet the hot gas expansion forming conditions.

[0067] In the hot gas expansion forming step, the formed portion of the arch beam 40 after heating (including the formation of the concave ribs 54) is realized through the hot gas expansion forming mold 100. Specifically, based on... Figures 10 to 12As shown, the hot air expansion forming mold 100 includes a hot air expansion upper mold 101, a hot air expansion lower mold 102, a high-pressure air source 103, an air pipe 104, two sets of sealing pushers 105, and two sets of hydraulic cylinders 106. The hot air expansion lower mold has a lower groove 107 that matches the arched beam 40, and the hot air expansion upper mold has a lower protrusion 108 that matches the arched beam 40. The lower groove 107 and the lower protrusion 108 are arranged opposite to each other. Both the lower groove 107 and the lower protrusion 108 include a middle forming section 109, a bending forming section 110, and an end forming section 111, respectively arranged from the middle to both ends, corresponding to the middle section 51, the bending section 52, and the end section 53 on the beam body 50. The two sets of sealing pushers 105 are connected to the high-pressure air source 103 via the air pipe 104, and the two sets of hydraulic cylinders 106 are connected to the two sets of sealing pushers 105. Meanwhile, the bottom wall of the lower groove 107 located in the middle forming section 109 and the top arm of the lower convex groove 108 located in the middle forming section 109 are both provided with ribs 112 to form the inner concave rib 54 structure.

[0068] In use, the arched beam 40, after being heated to a predetermined temperature, engages between the lower groove 107 and the lower protrusion 108. The middle pre-forming section 41, the bending pre-forming section 42, and the end pre-forming sections are located at the middle section 51, the bending section 52, and the end section 53, respectively. After the hot-expanding upper mold 101 and the hot-expanding lower mold 102 are closed, the two sets of sealing pushers 105 respectively connect with the ends of the two end pre-forming sections 43, specifically, the circular end of the end pre-forming section 43 connects with the sealing pusher 105. The hydraulic cylinder 106 drives the piston inside the sealing pusher 105 to achieve the connection and disconnection between the high-pressure air source 103 and the interior of the arched beam 40. When the high-pressure air source 103 is connected to the interior of the arched beam 40, the high-pressure air source 103 injects high-pressure inert gas into the arched beam 40. After the arched beam 40 expands under pressure, its sidewalls fit against the inner sidewalls of the lower groove 107 and the lower protrusion 108 to process the arched beam 40 into the beam body 50. The part that contacts the protruding rib 112 forms the concave rib 54. After the forming is completed, the hydraulic cylinder 106 is activated to block the high-pressure air source 103 and the beam body 50, separating the hot air expansion upper mold 101 and the hot air expansion lower mold 102, separating the sealing push head 105 from the beam body 50, and removing the beam body 50. After the beam body 50 cools down, the part of the end section 53 whose cross-sectional shape gradually transitions from rectangular to circular is cut off to obtain the required bumper.

[0069] It should be noted that during the process of high-pressure air source 103 inflating the arched beam 40, the hydraulic cylinder 106 can be controlled to connect both ends of the arched beam 40 to the high-pressure air source 103, or only one end can be connected to the high-pressure air source 103 while the other end is sealed. Both methods can achieve the thermal expansion and forming of the arched beam 40. Meanwhile, based on... Figure 12As shown, a sealing protrusion 113 is provided on the side wall of the middle forming section 109, which is inserted into the first positioning hole 11. During the process of the high-pressure air source 103 inflating the inside of the arch beam 40, the sealing protrusion 113 seals the first positioning hole 11 on the arch beam 40 to increase air tightness and reduce air leakage.

[0070] In this embodiment, for the portion of the arched beam 40 located at the first positioning hole 11 (i.e., the portion where the support box 20 is located), in order to ensure that its sidewall does not separate from the corrugated plate 22 on the support box 20 under the action of high-pressure gas, the lower groove 107 and the lower protrusion 108 require a certain shape design. Specifically, when the hot-air expansion upper mold 101 and the hot-air expansion lower mold 102 are closed, the bottom wall of the lower groove 107 and the lower protrusion 108 facing the first positioning hole 11 circumferentially directly contacts the arched beam 40, so that after high-pressure gas is filled, the portion at the first positioning hole 11 will not expand, ensuring that the sidewall of the arched beam 40 will not separate from the corrugated plate 22. The other parts of the arched beam 40 have a certain gap with the bottom wall of the lower groove 107 and the lower protrusion 108, which will expand after high-pressure gas is filled, eventually forming Figure 13 The beam body 50 is slightly recessed at the first positioning hole 11 shown. This recess also increases the strength at that location.

[0071] Meanwhile, for the concave rib 54, the concave rib 54 located near the first positioning hole 11 (i.e., the part where the support box 20 is set) is formed by pressing together the corresponding convex rib 112 during the molding process of the hot-air-expanded upper mold 101 and the hot-air-expanded lower mold 102. To ensure that the concave rib 54 at this location matches the surface shape of the corrugated plate 22, based on... Figure 14 As shown, it is placed in the recess on the surface of the corrugated plate 22. As for the processing of the remaining concave ribs 54, it is achieved by the pressing of the corresponding convex ribs 112 and the expansion effect after the high-pressure gas is injected during the mold closing process of the hot air expansion upper mold 101 and the hot air expansion lower mold 102.

[0072] The lightweight bumper manufacturing method in this embodiment increases support strength by spot welding the support box 20. Compared to aligning and welding two main bodies over a long distance, this method requires lower precision, is simpler, and is less expensive. Furthermore, instead of adding a reinforcing rib structure that runs through the entire bumper, increasing strength only near the bending point where strength requirements are high, and adding concave ribs 54 to the surface to improve overall strength, further reduces weight and achieves lightweighting. The first positioning hole 11 and the second positioning hole 23 facilitate positioning between the rectangular straight tube 10 and the support box 20 and enable spot welding connection.

[0073] Example 2:

[0074] This embodiment provides a bumper, based on Figure 2 , Figure 9 and Figure 14 As shown, the structure includes an arched main body and two support boxes 20. The cross-section of the arched main body is a hollow rectangle. The arched main body includes a central section 51, a bent section 52, and an end section 53 arranged sequentially from the middle to both ends. Each support box 20 includes a cylindrical support member 21 and corrugated plates 22 welded to both ends of the support member 21. The two support boxes 20 are symmetrically installed in the central section 51. The inner sidewall of the central section 51 is supported by the corrugated plates 22. The outer sidewalls of the central section 51 facing and away from the bending direction of the bent section 52 are provided with concave ribs 54.

[0075] Compared to adding a reinforcing rib structure that runs through the entire bumper, increasing the strength only near the bending point where strength requirements are high, and further enhancing the overall strength by adding a support box 20 structure and concave ribs 54 to the surface, can further reduce weight and achieve lightweighting. Specifically, to facilitate welding between the support box 20 and the arched body, two sets of first positioning holes 11 are provided through the side wall of the middle section 51, and the support box 20 has second positioning holes 23 that penetrate the two corrugated plates 22. When the support box 20 is placed inside the arched body, the two sets of first positioning holes 11 are aligned with the second positioning holes 23 on the two support boxes 20. The arched body and the support box 20 are fixed together by spot welding at the first positioning holes 11 and the second positioning holes 23.

[0076] Furthermore, based on Figure 14 As shown, the concave rib 54, aligned with the corrugated plate 22, is placed in a recess on the surface of the corrugated plate 22 to ensure a close fit between the support box 20 and the arched body. Simultaneously, this arrangement ensures that the corrugated plate 22 does not obstruct the formation of the concave rib 54 during its fabrication.

[0077] Furthermore, based on Figure 9 As shown, the side walls of the arched body are provided with weight-reducing holes 55 to further reduce the weight of the entire bumper.

[0078] In this embodiment, the bumper is made of BR1500HS high-strength steel, and the wall thickness of the arched body ranges from 1.8mm to 2.5mm, preferably 2mm.

[0079] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for manufacturing a lightweight bumper, characterized in that, include: Steps for making a rectangular straight tube: Make a rectangular straight tube (10) and open two sets of first positioning holes (11) through the side wall of the rectangular straight tube (10). The two sets of first positioning holes (11) are symmetrically arranged along the extension direction of the rectangular straight tube (10). Support box manufacturing steps: Weld corrugated plates (22) to both ends of the cylindrical support (21) to make a support box (20), and make a second positioning hole (23) through the corrugated plates (22) at both ends on the support box (20). Main beam blank fabrication steps: Place two sets of support boxes (20) into the rectangular straight tube (10), align the second positioning holes (23) on the two sets of support boxes (20) with the two sets of first positioning holes (11) on the rectangular straight tube (10) respectively, and support the corrugated plates (22) at both ends of the support boxes (20) against the inner sidewall of the rectangular straight tube (10); spot weld the support boxes (20) to the rectangular straight tube (10) at the first positioning hole (11) and the second positioning hole (23) to fix them, so that the rectangular straight tube (10) and the support boxes (20) are combined to form a main beam blank (30) with local reinforcement at the support boxes (20); Bending and forming steps: The main beam blank (30) is bent near both ends to form an arch beam (40). The arch beam (40) consists of a middle pre-forming section (41), a bending pre-forming section (42), and an end pre-forming section (43) from the middle to both ends. The support box (20) is located in the middle pre-forming section (41). Hot gas expansion forming steps: The arch beam (40) is processed into the main body of the beam (50) using the hot gas expansion forming process. The middle pre-forming section (41) is formed into the middle section (51), the bending pre-forming section (42) is formed into the bending section (52), and the end pre-forming section (43) is formed into the end section (53). In the middle section (51), concave ribs (54) are distributed on the outer side wall facing and away from the bending direction of the bending section (52). After the main body of the beam (50) is cooled, the required bumper is obtained.

2. The lightweight bumper manufacturing method as described in claim 1, characterized in that: In the process of making rectangular straight tubes, round tubes are made into rectangular straight tubes (10) by continuous rolling or steel coils are made into rectangular straight tubes (10) by a combination of cutting and continuous rolling and welding.

3. The lightweight bumper manufacturing method as described in claim 1, characterized in that: In the hot air expansion forming process, the formed part of the arch beam (40) after heating is realized by the hot air expansion forming mold (100); The hot air expansion forming mold (100) includes a hot air expansion upper mold (101), a hot air expansion lower mold (102), a high-pressure air source (103), an air pipe (104), two sets of sealing pushers (105), and two sets of hydraulic cylinders (106); the hot air expansion lower mold has a lower groove (107) matching the arch beam (40), and the hot air expansion upper mold has a lower protrusion (108) matching the arch beam (40), with the lower groove (107) and the lower protrusion (108) arranged opposite to each other; the two sets of sealing pushers (105) are respectively connected to the high-pressure air source (103) through the air pipe (104), Two sets of hydraulic cylinders (106) are connected to two sets of sealing pushers (105) respectively; the lower groove (107) and the lower protrusion (108) each include a middle forming section (109), a bending forming section (110) and an end forming section (111) respectively provided from the middle to the two ends, so as to correspond to the middle section (51), the bending section (52) and the end section (53) on the beam body (50) respectively; the bottom wall of the lower groove (107) located in the middle forming section (109) and the top arm of the lower protrusion (108) located in the middle forming section (109) are both provided with ribs (112); In the hot gas expansion forming step, the two sets of sealing pushers (105) are respectively connected to the ends of the two end pre-forming sections (43); after the arch beam (40) is compressed and expanded, its side wall is attached to the inner side wall of the lower groove (107) and the lower protrusion (108), and the part of the arch beam (40) that contacts the protrusion (112) forms an inner concave rib (54).

4. The lightweight bumper manufacturing method as described in claim 3, characterized in that: The sidewall of the middle forming section (109) is provided with a sealing protrusion (113) that is inserted into the first positioning hole (11).

5. The lightweight bumper manufacturing method as described in claim 3, characterized in that: A pressing step is also provided between the bending forming step and the hot air expansion forming step; Pressing steps: Press the two ends of the arch beam (40) to form a shape, so that the cross-sectional shape of the end preformed section (43) away from the bending preformed section (42) gradually transitions from rectangular to circular. In the hot air expansion forming step, the end of the preformed section (43) with a circular cross-section is connected to the sealing pusher (105); after the main beam (50) cools down, the part of the end section (53) whose cross-sectional shape gradually transitions from rectangular to circular is cut off to obtain the required bumper.

6. The lightweight bumper manufacturing method as described in claim 5, characterized in that: In the pressing step, the pressing and forming of both ends of the arch beam (40) is achieved by pressing mold (200); The pressing mold (200) includes an upper pressing mold (201), a lower pressing mold (202), and a cylindrical mandrel (203). Both the upper pressing mold (201) and the lower pressing mold (202) are provided with corresponding pressing half-grooves (204). The pressing half-grooves (204) on the upper pressing mold (201) and the pressing half-grooves (204) on the lower pressing mold (202) are combined to form a pressing groove (205) that transitions from a rectangle at one end to a circle at the other end. In the pressing step, the mandrel (203) is inserted into the end of the end preforming section (43) away from the bending preforming section (42), and then the end of the end preforming section (43) away from the bending preforming section (42) is placed into the pressing half groove (204) of the pressing lower mold (202). The pressing upper mold (201) and the pressing lower mold (202) are closed to press the end of the arch beam (40) into shape.

7. The lightweight bumper manufacturing method as described in claim 1, characterized in that: In the manufacturing process of the rectangular straight tube, the material of the rectangular straight tube (10) is BR1500HS, and the wall thickness of the rectangular straight tube (10) ranges from 1.8 to 2.5 mm. In the hot gas expansion forming step, the heating temperature range of the arch beam (40) is 900-1000℃, and the hot gas expansion gas pressure range is 28-32MPa.

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