Power battery rolling steel lower box forming method, product and vehicle

Abstract

The invention relates to a power battery rolling steel lower box forming method, a product and a vehicle. The rolling steel lower box body product of the power battery comprises a lower box body frame assembly, a heat management assembly and a bottom protection assembly, the lower box body frame assembly comprises a lower box body frame, a mounting assembly and an internal reinforcing assembly; the lower box body frame comprises a main frame and an auxiliary frame; the main bezel includes a bezel body and an internal reinforcement. The main frame and the auxiliary frame share a common mode and are both square-shaped sections; only one tailor-welding bead is arranged, and after the lower box body frame is formed, the lower box body frame is located on the inner side of the lower box body and is not affected by outer sealing of the lower box body; as the square-shaped section is only provided with one tailor-welding bead, after the frame of the lower box body is formed, the inner side and the outer side of the lower box body are not provided with profile splicing beads; the four right angles of the main frame and the two right angles of the auxiliary frame are all bent to replace traditional sectional material beam splicing welding. The interiors of the side surfaces of the main frame are connected through the reinforcers, so that the strength of the power battery is greatly improved, the number of mold opening parts is reduced, and the cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of roll-formed steel lower boxes for power batteries, and in particular relates to a novel method for forming a roll-formed steel lower box for power batteries, a product and a vehicle. Background Art

[0002] In the existing technology, in order to improve the energy density of power batteries, the shell material is mainly aluminum alloy, among which extruded aluminum profiles are the most widely used. In order to reduce costs, steel battery packs are gradually being paid attention to by OEMs and battery manufacturers. The design of the roll-pressed steel lower box of power batteries and its forming method have become a key technology that has attracted much attention from major automakers and battery manufacturers.

[0003] At present, the design and forming of the lower box of the power battery roll-formed steel have the following problems:

[0004] 1. Welding corrosion: Since steel has a worse corrosion resistance than aluminum, especially arc welding welds, they are very susceptible to corrosion even after electrophoresis treatment.

[0005] 2. Sealing failure: As the wall thickness of the lower box of the power battery rolled steel is relatively thin, arc welding often easily penetrates, resulting in sealing failure.

[0006] 3. Poor mechanical strength: The wall thickness of the box body is relatively thin under roll forming, and local reinforcement cannot be achieved.

[0007] 4. High mold opening cost: There are many types of roll-formed profile cross-sections, and the mold opening cost is high.

[0008] 5. High manufacturing cost: The sealing surface requires laser welding, which has high welding cost.

[0009] Based on this, it is urgent to develop a new method for forming the lower box of power battery roll-formed steel to effectively solve the above problems. Summary of the invention

[0010] The purpose of the present invention is to provide a new method, product and vehicle for forming a new type of rolled steel lower box of a power battery, so as to solve the problems of welding corrosion, sealing failure, poor mechanical strength and high manufacturing mold opening cost existing in the rolled steel lower box of the power battery at this stage.

[0011] The objective of the present invention is achieved through the following technical solutions:

[0012] A method for forming a lower box body of a power battery by roll-pressing steel, comprising the following steps:

[0013] A. Main frame forming method:

[0014] A1. Rolling profile forming: Rolling into a U-shaped cross-section profile, the profile joint is in the middle of the side, and the joint is welded by high-frequency welding;

[0015] A2. Cutting of roll-formed profiles: Cut the roll-formed profiles to the corresponding length according to the perimeter of the frame.

[0016] A3. Cutting the bending angle of the roll-formed profile: According to the four right-angle positions of the main frame, the high-frequency welded joint side of the roll-formed profile in step A2 is laser cut, and the incision is a right-angle triangle;

[0017] A4. Cutting of installation holes for rolled profiles: Pre-drill holes for pull rivets, blind rivets, and spot welding according to the corresponding positions of the main frame;

[0018] A5. Main frame reinforcement profile forming: Rolling into a U-shaped cross-section profile, the profile joint is in the middle of the side, and the joint is welded by high-frequency welding;

[0019] A6. Cutting of installation holes for main frame reinforcement: Pre-drill holes for pull rivets and blind rivets at the corresponding positions of the installation holes;

[0020] A7. Gluing of reinforcement parts: Pre-glue the sides of reinforcement parts;

[0021] A8. Filling the main frame and reinforcements: Fill the reinforcements into the corresponding positions inside the main frame;

[0022] A9. Connection between the main frame and the reinforcement: Connect the reinforcement to the main frame with blind rivets;

[0023] A10. Main frame bending: bend the four right-angle positions of the main frame, i.e. the right-angle triangle cut positions, 90 degrees to form the required frame body;

[0024] A11. Main frame welding: Laser welding is performed on the upper surface, lower surface and vertical surface joints of the folded corners;

[0025] A12, the main frame is formed;

[0026] B. Secondary frame forming method:

[0027] B1. Rolling profile forming: Rolling into a U-shaped cross-section profile, the profile joint is in the middle of the side, and the joint is welded by high-frequency welding;

[0028] B2. Cutting of roll-formed profiles: Cut the roll-formed profiles to the corresponding length according to the perimeter of the secondary frame;

[0029] B3, cutting of bending angles of roll-formed profiles: laser cutting is performed on the high-frequency welded joint side of the roll-formed profile in step S13 according to the two right-angle positions of the main frame, and the incision is a right-angle triangle;

[0030] B4. Cutting of installation holes for rolled profiles: pre-drill holes according to the corresponding positions of the secondary frames;

[0031] B5. Bending of the secondary frame: bend the two right-angle positions of the main frame, i.e. the right-angle triangle cut positions, 90 degrees to form the required secondary frame;

[0032] B6. Secondary frame welding: Laser welding is performed on the upper surface, lower surface and vertical surface joints of the folded corners;

[0033] B7, the secondary frame is formed;

[0034] B8. Positioning of main frame and sub-frame: The main frame and sub-frame are positioned by positioning tooling;

[0035] B9. Main frame and sub-frame welding: Laser welding the positioned main and sub-frames;

[0036] B10, the box frame is formed.

[0037] A power battery roll-formed steel lower box product, comprising a lower box frame assembly, a thermal management assembly and a bottom protection assembly; the lower box frame assembly comprises a lower box frame, a mounting assembly and an internal reinforcement assembly, and the lower box frame comprises a main frame and a secondary frame;

[0038] The main frame includes a frame body and an internal reinforcement; the internal reinforcement is filled inside the frame body, and on the inner side, the reinforcement is connected to the frame body through a blind rivet, and on the lower side, the reinforcement is connected to the frame body through a rivet nut, and on the outer side, the reinforcement is connected to the frame body through a foamed structural adhesive; the frame body is a U-shaped frame structure, and a rolled profile is cut at four right-angle positions of the U-shaped frame structure by laser cutting, and a triangular opening is pre-opened on the upper and lower sides of the sun-shaped cross-section, and a rectangular opening is pre-opened on the inner side, and then the rolled profile is bent at the right angle to bend the rolled profile into a U-shaped structure; the upper side, the lower side and the inner side of the bend are welded; the corner is bent; the cross section of the frame body is formed by roll forming, and the welding position of the interface of the rolled material cross section is approximately in the middle of the inner side, and a blind rivet opening is reserved on the side of the frame body; a rivet nut opening is reserved at the bottom of the frame body;

[0039] The secondary frame and the frame body are rolled together, and their cross-sections are formed by roll forming. The welding position of the interface of the rolled material cross-section is approximately in the middle of the inner side. The secondary frame is composed of a rolled profile at two right-angle positions of the U-shaped frame structure. Triangular openings are pre-opened on the upper and lower sides of the I-shaped cross-section, and a rectangular opening is pre-opened on the inner side. The right angles are bent to bend the rolled profile into a U-shaped structure. The upper, lower and inner sides of the bends are welded, and the corners are bent.

[0040] Furthermore, the thickness of the structural adhesive is 0.5-1.0 mm.

[0041] Furthermore, the internal reinforcement is filled in the straight section of the frame body, and the length of each corresponding reinforcement section is 50-100 mm less than the straight section length of the frame body in this area. The end of each corresponding reinforcement section is 25-50 mm away from the end of the frame body in this area.

[0042] Furthermore, the main body material of the frame is steel, with a U-shaped cross-section, a cross-sectional width of 25mm-35mm, a cross-sectional height of 95mm-115mm, and a wall thickness of 0.8-1.5mm; the opening spacing of the blind rivets is 80-100mm, and the opening diameter is 5-6mm; the opening spacing of the rivet nuts is 60-70mm, and the opening diameter is 7-8mm.

[0043] Furthermore, the internal reinforcement is made of steel or aluminum, with a U-shaped or R-shaped cross-section, a cross-sectional width of 22mm-32mm, a cross-sectional height of 35mm-45mm, and a wall thickness of 0.8-1.5mm; the outer cross-sectional width of the internal reinforcement is 0.5mm-1mm smaller than the inner cross-sectional width of the frame body.

[0044] Furthermore, openings for blind rivets are reserved on the sides of the internal reinforcement, with a spacing of 80-100mm between the openings and a diameter of 5-6mm; the size and spacing of the openings for blind rivets on the internal reinforcement are consistent with the corresponding positions of the frame body; openings for rivet nuts are reserved at the bottom of the internal reinforcement, with a spacing of 60-70mm between the openings and a diameter of 7-8mm; the size and spacing of the openings for rivet nuts at the bottom of the internal reinforcement are consistent with the corresponding positions of the frame body.

[0045] Furthermore, the secondary frame material is steel, the cross-section is a square, the cross-section width is 25mm-35mm, the cross-section height is 95mm-115mm, and the wall thickness is 0.8-1.5mm.

[0046] Furthermore, the side of the secondary frame is reserved for blind rivet openings, the blind rivet opening spacing is 80-100mm, and the opening diameter is 5-6mm. The bottom of the secondary frame is reserved for rivet nut openings, the rivet nut opening spacing is 60-70mm, and the opening diameter is 7-8mm.

[0047] A vehicle having a power battery rolled steel lower box product.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] 1. The method for forming the lower box body of the power battery roll-pressed steel of the present invention uses a common mold for the main frame and the secondary frame, both of which have a square-shaped cross-section, thereby reducing the mold opening cost;

[0050] 2. The traditional rectangular cross-section has two splicing weld seams. After the lower box body frame is formed, one weld seam is on the outside of the battery pack or welded to the outer wall. Due to the outer sealing requirement of the lower box body, the welding requirement is relatively high, and laser welding needs to be used for welding, resulting in low welding efficiency and high welding cost. The square cross-section has only one splicing weld seam. After the lower box body frame is formed, it is on the inner side of the lower box body and is not affected by the outer sealing of the lower box body. The welding requirement is relatively low, and high-frequency welding can be used for welding, with high welding efficiency and low welding cost.

[0051] 3. Since the square cross-section has only one splicing weld seam, after the lower box body frame is formed, it is on the inner side of the lower box body, and there is no profile splicing weld seam on the outside, so there is no risk of welding defects such as weld penetration, and the sealing effect is good. Without the profile splicing weld seam on the outside, the welding workload is reduced, and the welding cost is further reduced.

[0052] 4. At the four right angles of the main frame and the two right angles of the auxiliary frame, bending is used to replace the traditional profile beam splicing weld, without the risk of welding defects and with good sealing effect.

[0053] 5. The inner side of the main frame is connected by a reinforcing member, which greatly improves the strength of the power battery and reduces the number of mold parts, thus reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0055] Figure 1-Figure 2 FIGS. 18 are schematic diagrams of the power battery roll-formed steel lower box body - lower box body frame assembly, thermal management assembly, and bottom protection assembly;

[0056] Figure 3-Figure 4 FIGS. 22 are schematic diagrams of the lower box body frame assembly - lower box body frame, mounting assembly, and internal reinforcement assembly;

[0057] Figure 5 FIGS. 26 are schematic diagrams of the lower box body frame - main frame and auxiliary frame;

[0058] Figure 6-Figure 7 FIGS. 30 are schematic diagrams of the main frame - frame body and internal reinforcement member;

[0059] Figure 8-Figure 9 FIGS. 34 are schematic diagrams of the frame body;

[0060] FIGS. 10 - 11 are schematic diagrams of the internal reinforcement member;

[0061] Figure 12-13 FIGS. 41 are schematic diagrams of the auxiliary frame;

[0062] Fig.14 It is a schematic diagram of roller profile forming;

[0063] Fig.15 It is a schematic diagram of the cutting of the bending angle of the rolled profile;

[0064] Fig.16 Schematic diagram of cutting installation holes for roll-formed profiles;

[0065] Fig.17 Schematic diagram of internal reinforcement. DETAILED DESCRIPTION

[0066] The present invention will be further described below in conjunction with embodiments:

[0067] The present invention provides a method for forming a lower box body of a power battery roll-pressed steel, which effectively solves the sealing failure problem of the lower box body of the battery pack by minimizing external welding; increases the strength of the battery pack by using a square-shaped frame + internal reinforcement solution; and reduces the number of zero levels by maximizing platformization, thereby reducing mold opening costs and manufacturing costs. The forming method includes the following steps:

[0068] A. Main frame forming method:

[0069] A1. Roll-formed profile forming: Roll-formed into a U-shaped cross-section profile, the profile joint is in the middle of the side, and the joint is welded by high-frequency welding.

[0070] A2. Cutting of roll-formed profiles: Cut the roll-formed profiles to the corresponding length according to the perimeter of the frame.

[0071] A3. Cutting of bending corners of rolled profiles: According to the four right-angle positions of the main frame, laser cutting is performed on the high-frequency welded joint side of the rolled profile in step A2, and the incision is a right-angle triangle.

[0072] A4. Cutting of installation holes for rolled profiles: Pre-drilling holes for pull rivets, blind rivets, spot welding, etc., according to the corresponding positions of the main frame.

[0073] A5. Main frame reinforcement profile forming: Roll-pressed into a U-shaped cross-section profile, the profile joint is in the middle of the side, and the joint is welded by high-frequency welding.

[0074] A6. Cutting of installation holes for main frame reinforcement: Pre-drill holes for pull rivets and blind rivets at the corresponding positions of the installation holes.

[0075] A7. Gluing of reinforcement parts: Pre-glue the side of the reinforcement parts (non-opening surface).

[0076] A8. Filling the main frame and reinforcements: Fill the reinforcements into the corresponding positions inside the main frame.

[0077] A9. Connection between the main frame and the reinforcement: Connect the reinforcement to the main frame with blind rivets.

[0078] A10. Bending the main frame: bend the four right-angled positions of the main frame, i.e. the right-angled triangle cut positions, 90 degrees to form the required frame body.

[0079] A11. Main frame welding: Laser welding is performed on the upper surface, lower surface and vertical joints of the folded corners.

[0080] A12, the main frame is formed.

[0081] B. Secondary frame forming method:

[0082] B1. Roll-formed profile forming: Roll-formed into a U-shaped cross-section profile, the profile joint is in the middle of the side, and the joint is welded by high-frequency welding.

[0083] B2. Cutting of roll-formed profiles: Cut the roll-formed profiles to the corresponding length according to the perimeter of the secondary frame.

[0084] B3. Cutting of bending corners of rolled profiles: According to the two right-angle positions of the main frame, laser cutting is performed on the high-frequency welded joint side of the rolled profile in step B1, and the incision is a right-angle triangle.

[0085] B4. Cutting of installation holes for rolled profiles: Pre-drill holes according to the corresponding positions of the secondary frames.

[0086] B5. Bending the secondary frame: Bend the two right-angle positions of the main frame, i.e. the right-angle triangle cutouts, 90 degrees to form the required secondary frame.

[0087] B6. Secondary frame welding: Laser welding is performed on the upper surface, lower surface and vertical surface joints of the folded corners.

[0088] B7. The secondary frame is formed.

[0089] B8. Positioning of main frame and sub-frame: The main frame and sub-frame are positioned by positioning tooling.

[0090] B9. Main frame and sub-frame welding: Laser weld the positioned main and sub-frames.

[0091] B10, the box frame is formed.

[0092] The present invention also provides a power battery roll-formed steel lower box product, including a lower box frame assembly, a thermal management assembly and a bottom protection assembly. The lower box frame assembly includes a lower box frame, a mounting assembly and an internal reinforcement assembly. The innovation of the present invention is to provide a new structure of a lower box frame, and the lower box frame includes a main frame and a secondary frame.

[0093] The main frame includes a frame body and an internal reinforcement.

[0094] The internal reinforcement is filled inside the frame body. In the inner direction, the reinforcement is connected to the frame body through a blind rivet. In the lower direction, the reinforcement is connected to the frame body through a rivet nut. In the outer direction, the reinforcement is connected to the frame body through a foamed structural adhesive. The thickness of the structural adhesive is 0.5-1.0mm. The internal reinforcement is filled in the straight section of the frame body. The length of each corresponding reinforcement section is 50-100mm less than the length of the straight section of the frame body in this area. The end of each corresponding reinforcement section is 25-50mm away from the end of the frame body in this area.

[0095] The frame body is a U-shaped frame structure, which is made of a rolled profile. At four right-angle positions of the U-shaped frame structure, a triangular opening is pre-opened on the upper and lower sides of the U-shaped section through laser cutting, and a rectangular opening is pre-opened on the inner side. Then, it is bent at the right angle to bend the rolled profile into a U-shaped structure. The upper, lower and inner sides of the bend are welded. The corners are bent, not welded. The external sealing structure of the battery pack is well guaranteed. The main material of the frame is steel, with a U-shaped cross-section, a cross-sectional width of 25mm-35mm, a cross-sectional height of 95mm-115mm, and a wall thickness of 0.8-1.5mm. The cross-section of the frame body is roll-formed, and the welding position of the roll-formed material cross-section interface is approximately in the middle of the inner side, which can well ensure the external sealing structure of the battery pack. The side of the frame body is reserved for blind rivet openings, with a blind rivet opening spacing of 80-100mm and an opening diameter of 5-6mm. The bottom of the frame body is reserved with rivet nut openings, the rivet nut opening spacing is 60-70mm, and the opening diameter is 7-8mm.

[0096] The material of the internal reinforcement is steel or aluminum, and the cross-section is a square or a sun shape, the cross-section width is 22mm-32mm, the cross-section height is 35mm-45mm, and the wall thickness is 0.8-1.5mm. The outer cross-sectional width of the internal reinforcement is 0.5mm-1mm smaller than the inner cross-sectional width of the frame body. Blind rivet openings are reserved on the side of the internal reinforcement, the spacing between the blind rivet openings is 80-100mm, and the opening diameter is 5-6mm. The size and spacing of the blind rivet openings of the internal reinforcement are consistent with the corresponding positions of the frame body. The bottom of the internal reinforcement is reserved for rivet nut openings, the spacing between the rivet nut openings is 60-70mm, and the opening diameter is 7-8mm. The size and spacing of the rivet nut openings at the bottom of the internal reinforcement are consistent with the corresponding positions of the frame body.

[0097] The material of the secondary frame is steel, with a U-shaped cross section, a cross-sectional width of 25mm-35mm, a cross-sectional height of 95mm-115mm, and a wall thickness of 0.8-1.5mm. The cross section of the secondary frame is formed by roll forming, and the welding position of the interface of the roll material cross section is approximately in the middle of the inner side, which can well ensure the external sealing structure of the battery pack. The side of the secondary frame is reserved for openings for blind rivets, with a spacing of 80-100mm between the openings of the blind rivets and an opening diameter of 5-6mm. The bottom of the secondary frame is reserved for openings for rivet nuts, with a spacing of 60-70mm between the openings of the rivet nuts and an opening diameter of 7-8mm. The secondary frame is made of a rolled profile at two right angles to the U-shaped frame structure. Through laser cutting, a triangular opening is pre-opened on the upper and lower sides of the U-shaped cross section, and a rectangular opening is pre-opened on the inner side, and then bent at the right angle to bend the rolled profile into a U-shaped structure. The upper, lower and inner sides of the bend are welded. The corner is bent, not welded. The external sealing structure of the battery pack is well guaranteed. The secondary frame material, cross-sectional dimensions and wall thickness are the same as those of the frame body, and are rolled together.

[0098] The present invention also provides a vehicle, including the above-mentioned battery pack product. According to the vehicle of the present invention, the vehicle has a power battery roll-pressed steel lower box product, which not only reduces the production cost, but also has good sealing performance, ensuring the normal working environment of the battery pack, so that the battery pack provides sufficient power for the vehicle, and the vehicle can run smoothly and powerfully.

[0099] In the present invention, the inside of the battery pack is the inner side, the outside of the battery pack is the outer side, the bottom of the battery pack is the lower side, the upper part of the battery pack is the upper side, the boss side of the battery pack is the front, the opposite direction is the rear, and the two sides are the left side and the right side.

[0100] Example 1

[0101] A power battery roll-formed steel lower box product, including: a lower box frame component, a thermal management component, and a bottom protection component, such as Figure 1-Figure 2 shown.

[0102] like Figure 3-Figure 4 As shown, the lower box frame assembly includes a lower box frame, a mounting assembly, and an internal reinforcement assembly.

[0103] like Figure 5 As shown, the lower box frame includes a main frame and a secondary frame.

[0104] like Figure 6-Figure 7 As shown, the main frame includes a frame body and an internal reinforcement.

[0105] Preferably, the internal reinforcement is filled inside the frame body, and on the inner side, the reinforcement is connected to the frame body through blind rivets, and on the lower side, the reinforcement is connected to the frame body through rivet nuts, and on the outer side, the reinforcement is connected to the frame body through foamed structural adhesive, and the thickness of the structural adhesive is 0.5 mm.

[0106] The inner reinforcement is filled in the straight line section of the frame body, and the length of each corresponding reinforcement section is 50-100 mm less than the straight line section length of the frame body in this area. The end of each corresponding reinforcement section is 25-50 mm away from the end of the frame body in this area.

[0107] Preferably, the internal reinforcement is filled in the straight line section of the frame body, the length of the left and right side beams of the frame body is 1480 mm, the length of the rear frame is 1360 mm, and the length of the left and right front frames is 507 mm.

[0108] Preferably, the left and right reinforcements are 1410 mm long, the rear reinforcement is 1290 mm long, and the front left and right reinforcements are 437 mm long.

[0109] like Figure 8-Figure 9 As shown, the frame body is a circular frame structure, which is made of a rolled profile. At four right angles of the circular frame structure, a triangular opening is pre-opened on the upper and lower sides of the sun-shaped section, and a rectangular opening is pre-opened on the inner side, and then the rolled profile is bent at the right angle to be bent into a circular structure. The upper side, lower side and inner side of the bend are welded. The corners are bent, not welded. The outer sealing structure of the battery pack is well guaranteed.

[0110] Preferably, the frame body is made of steel, has a U-shaped cross section, a width of 32 mm, a height of 110 mm, and a wall thickness of 1 mm.

[0111] The frame main body cross section is roll-formed, and the weld position of the roll-formed material cross section interface is approximately in the middle of the inner side, which can well ensure the external sealing structure of the battery pack.

[0112] Preferably, openings for blind rivets are reserved on the side of the frame body, the spacing between the openings of the blind rivets is 95 mm, and the opening diameter is 5.5 mm.

[0113] Preferably, rivet nut openings are reserved at the bottom of the frame body, the rivet nut opening spacing is 65 mm, and the opening diameter is 7.5 mm.

[0114] As shown in FIG. 10-FIG 11 , as a preferred embodiment, the material of the internal reinforcement is steel, the cross section is a square shape, the cross section width is 29.5 mm, the cross section height is 40 mm, and the wall thickness is 1 mm.

[0115] Preferably, the outer cross-sectional width of the internal reinforcement is 0.5 mm smaller than the inner cross-sectional width of the frame body.

[0116] Preferably, blind rivet openings are reserved on the side of the reinforcement, the blind rivet opening spacing is 95 mm, and the opening diameter is 5.5 mm.

[0117] The opening size and spacing of the blind rivets of the internal reinforcement are consistent with the corresponding positions of the frame body.

[0118] Preferably, rivet nut openings are reserved at the bottom of the reinforcement, the rivet nut opening spacing is 65 mm, and the opening diameter is 7.5 mm.

[0119] The opening size and spacing of the rivet nuts at the bottom of the internal reinforcement are consistent with the corresponding positions of the frame body.

[0120] Example 2

[0121] A method for forming a frame of a power battery roll-formed steel lower box body, comprising the following steps:

[0122] A Main frame forming method:

[0123] A1. Rolling profile forming: Rolling into a U-shaped cross-section profile, the profile joint is in the middle of the side, and the joint is welded by high-frequency welding, such as Fig.14 shown.

[0124] A2. Cutting of roll-formed profiles: Cut the roll-formed profiles to the corresponding length according to the perimeter of the frame.

[0125] A3. Cutting of bending angles of rolled profiles: According to the four right-angle positions of the main frame, laser cutting is performed on the high-frequency welded joint side of the rolled profile in step A2. The incision is a right-angle triangle, such as Fig.15 shown.

[0126] A4. Cutting of installation holes for rolled profiles: Pre-drilling holes for pull rivets, blind rivets, spot welding, etc. according to the corresponding positions of the main frame. Fig.16 shown.

[0127] A5. Main frame reinforcement profile forming: Roll-pressed into a U-shaped cross-section profile, the profile joint is in the middle of the side, and the joint is welded by high-frequency welding.

[0128] A6. Cutting of installation holes for main frame reinforcement: Pre-drill holes for pull rivets and blind rivets at the corresponding positions of the installation holes.

[0129] A7. Gluing of reinforcement parts: Pre-glue the side of the reinforcement parts (non-opening surface).

[0130] A8. Filling the main frame and reinforcements: Fill the reinforcements into the corresponding positions inside the main frame.

[0131] A9. Connection between the main frame and the reinforcement: Connect the reinforcement to the main frame with blind rivets.

[0132] A10. Bending the main frame: bend the four right-angled positions of the main frame, i.e. the right-angled triangle cut positions, 90 degrees to form the required frame body.

[0133] A11. Main frame welding: Laser welding is performed on the upper surface, lower surface and vertical joints of the folded corners.

[0134] A12, the main frame is formed.

[0135] B. Secondary frame forming method:

[0136] B1. Roll-formed profile forming: Roll-formed into a U-shaped cross-section profile, the profile joint is in the middle of the side, and the joint is welded by high-frequency welding.

[0137] B2. Cutting of roll-formed profiles: Cut the roll-formed profiles to the corresponding length according to the perimeter of the secondary frame.

[0138] B3. Cutting of bending corners of rolled profiles: According to the two right-angle positions of the main frame, laser cutting is performed on the high-frequency welded joint side of the rolled profile in step B1, and the incision is a right-angle triangle.

[0139] B4. Cutting of installation holes for rolled profiles: Pre-drill holes according to the corresponding positions of the secondary frames.

[0140] B5. Bending the secondary frame: Bend the two right-angle positions of the main frame, i.e. the right-angle triangle cutouts, 90 degrees to form the required secondary frame.

[0141] B6. Secondary frame welding: Laser welding is performed on the upper surface, lower surface and vertical surface joints of the folded corners.

[0142] B7. The secondary frame is formed.

[0143] B8. Positioning of main frame and sub-frame: The main frame and sub-frame are positioned by positioning tooling.

[0144] B9. Main frame and sub-frame welding: Laser weld the positioned main and sub-frames.

[0145] B10, the box frame is formed.

[0146] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for forming a lower box body of a power battery roll-pressed steel, characterized in that: The following steps are involved: A. Main frame forming method: A1. Rolling profile forming: Rolling into a U-shaped cross-section profile, the profile joint is in the middle of the side, and the joint is welded by high-frequency welding; A2. Cutting of roll-formed profiles: Cut the roll-formed profiles to the corresponding length according to the perimeter of the frame. A3. Cutting the bending angle of the roll-formed profile: According to the four right-angle positions of the main frame, the high-frequency welding joint side of the roll-formed profile in step A2 is laser cut, and the incision is a right-angle triangle; A4. Cutting of installation holes for rolled profiles: Pre-drill holes for pull rivets, blind rivets, and spot welding according to the corresponding positions of the main frame; A5. Main frame reinforcement profile forming: Rolling into a U-shaped cross-section profile, the profile joint is in the middle of the side, and the joint is welded by high-frequency welding; A6. Cutting of installation holes for main frame reinforcement: Pre-drill holes for pull rivets and blind rivets at the corresponding positions of the installation holes; A7. Gluing of reinforcement parts: Pre-glue the sides of reinforcement parts; A8. Filling the main frame and reinforcements: Fill the reinforcements into the corresponding positions inside the main frame; A9. Connection between the main frame and the reinforcement: Connect the reinforcement to the main frame with blind rivets; A10. Main frame bending: bend the four right-angle positions of the main frame, i.e. the right-angle triangle cut positions, 90 degrees to form the required frame body; A11. Main frame welding: Laser welding is performed on the upper surface, lower surface and vertical surface joints of the folded corners; A12, the main frame is formed; B. Secondary frame forming method: B1. Rolling profile forming: Rolling into a U-shaped cross-section profile, the profile joint is in the middle of the side, and the joint is welded by high-frequency welding; B2. Cutting of roll-formed profiles: Cut the roll-formed profiles to the corresponding length according to the perimeter of the secondary frame; B3, cutting of bending angles of roll-formed profiles: laser cutting is performed on the high-frequency welded joint side of the roll-formed profile in step B1 according to the two right-angle positions of the main frame, and the incision is a right-angle triangle; B4. Cutting of installation holes for rolled profiles: pre-drill holes according to the corresponding positions of the secondary frames; B5. Bending of the secondary frame: bend the two right-angle positions of the main frame, i.e. the right-angle triangle cut positions, 90 degrees to form the required secondary frame; B6. Secondary frame welding: Laser welding is performed on the upper surface, lower surface and vertical surface joints of the folded corners; B7, the secondary frame is formed; B8. Positioning of main frame and sub-frame: The main frame and sub-frame are positioned by positioning tooling; B9. Main frame and sub-frame welding: Laser welding the positioned main and sub-frames; B10, the box frame is formed.

2. A power battery roll-formed steel lower box product, comprising a lower box frame assembly, a thermal management assembly and a bottom protection assembly; the lower box frame assembly comprises a lower box frame, a mounting assembly and an internal reinforcement assembly, characterized in that: The lower box frame includes a main frame and a secondary frame; The main frame includes a frame body and an internal reinforcement; the internal reinforcement is filled inside the frame body, and on the inner side, the reinforcement is connected to the frame body through a blind rivet, and on the lower side, the reinforcement is connected to the frame body through a rivet nut, and on the outer side, the reinforcement is connected to the frame body through a foamed structural adhesive; the frame body is a U-shaped frame structure, and a rolled profile is cut at four right-angle positions of the U-shaped frame structure by laser cutting, and a triangular opening is pre-opened on the upper and lower sides of the sun-shaped cross-section, and a rectangular opening is pre-opened on the inner side, and then the rolled profile is bent at the right angle to bend the rolled profile into a U-shaped structure; the upper side, the lower side and the inner side of the bend are welded; the corner is bent; the cross section of the frame body is formed by roll forming, and the welding position of the interface of the rolled material cross section is approximately in the middle of the inner side, and a blind rivet opening is reserved on the side of the frame body; a rivet nut opening is reserved at the bottom of the frame body; The secondary frame and the frame body are rolled together, and their cross-sections are formed by roll forming. The welding position of the interface of the rolled material cross-section is approximately in the middle of the inner side. The secondary frame is composed of a rolled profile at two right-angle positions of the U-shaped frame structure. Triangular openings are pre-opened on the upper and lower sides of the I-shaped cross-section, and a rectangular opening is pre-opened on the inner side. The right angles are bent to bend the rolled profile into a U-shaped structure. The upper, lower and inner sides of the bends are welded, and the corners are bent.

3. A power battery roll-formed steel lower box product according to claim 2, characterized in that: The thickness of the structural adhesive is 0.5-1.0 mm.

4. A power battery roll-formed steel lower box product according to claim 2, characterized in that: The inner reinforcement is filled in the straight line section of the frame body, and the length of each corresponding reinforcement section is 50-100 mm less than the straight line section length of the frame body in this area. The end of each corresponding reinforcement section is 25-50 mm away from the end of the frame body in this area.

5. The power battery roll-formed steel lower box product according to claim 2, characterized in that: The main material of the frame is steel, with a U-shaped cross-section, a cross-sectional width of 25mm-35mm, a cross-sectional height of 95mm-115mm, and a wall thickness of 0.8-1.5mm; the opening spacing of the blind rivets is 80-100mm, and the opening diameter is 5-6mm; the opening spacing of the rivet nuts is 60-70mm, and the opening diameter is 7-8mm.

6. A power battery roll-formed steel lower box product according to claim 2, characterized in that: The internal reinforcement is made of steel or aluminum, with a U-shaped or R-shaped cross-section, a cross-sectional width of 22mm-32mm, a cross-sectional height of 35mm-45mm, and a wall thickness of 0.8-1.5mm; the outer cross-sectional width of the internal reinforcement is 0.5mm-1mm smaller than the inner cross-sectional width of the frame body.

7. The power battery roll-formed steel lower box product according to claim 2, characterized in that: Blind rivet openings are reserved on the side of the internal reinforcement, with the opening spacing of 80-100mm and the opening diameter of 5-6mm; the opening size and spacing of the blind rivet on the internal reinforcement are consistent with the corresponding positions of the frame body; rivet nut openings are reserved at the bottom of the internal reinforcement, with the opening spacing of 60-70mm and the opening diameter of 7-8mm; the opening size and spacing of the rivet nuts at the bottom of the internal reinforcement are consistent with the corresponding positions of the frame body.

8. The power battery roll-formed steel lower box product according to claim 2, characterized in that: The secondary frame is made of steel, has a square cross section, a cross section width of 25mm-35mm, a cross section height of 95mm-115mm, and a wall thickness of 0.8-1.5mm.

9. The power battery roll-formed steel lower box product according to claim 2, characterized in that: The side of the secondary frame is reserved with openings for blind rivets, the spacing between the openings of the blind rivets is 80-100mm, and the opening diameter is 5-6mm. The bottom of the secondary frame is reserved with openings for rivet nuts, the spacing between the openings of the rivet nuts is 60-70mm, and the opening diameter is 7-8mm.

10. A vehicle, characterized in that: The vehicle has a power battery rolled steel lower box product as described in claims 2-9.

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