Forming Process of the Upper Cover Plate of an Electric Vehicle Battery Box

Abstract

The present invention discloses a forming process for the upper cover plate of an electric vehicle battery box. After the sheet metal enters the forming die assembly, four forming processes are carried out within the forming die assembly, namely primary stretching forming, secondary trimming and punching forming, tertiary trimming and punching forming, and finishing forming. Therefore, through multiple forming processes, common problems that occur in the prior art can be effectively eliminated, especially the problems of distortion and cracking are optimally solved. During the forming process, by reducing the difference between the principal strain and the secondary strain, it is possible to ensure that the product does not crack or wrinkle, and at the same time reduce distortion to ensure that the product dimensions meet the requirements.

Description

Technical Field

[0001] The invention relates to the technical field of molding technology, in particular to a molding technology for an upper cover plate of a battery box of an electric vehicle. Background Art

[0002] At present, as people's environmental awareness is getting stronger and stronger, more and more people choose new energy electric vehicles as their means of transportation. The battery box is an important component in electric vehicles. It is the main body of the battery pack. It must have sufficient strength to fix the battery pack, and it must also have dustproof and beautiful functions. Usually the battery box includes an upper cover plate, such as the attached Figure 1 As shown in , it includes a rectangular main plane 1-1, the circumference of the main plane 1-1 is a flange circumference 1-2 extending upward from the main plane, and a plurality of small mounting holes 1-6 are arranged along the flange circumference 1-2. In the middle of the main plane 1-1, there is an intermediate rib 1-3 extending to the two opposite sides of the main plane and protruding downward from the main plane. With the intermediate rib 1-3 as the boundary, the main planes on both sides thereof are arranged with a plurality of supporting ribs 1-4 protruding upward from the main plane and perpendicular to the intermediate rib 1-3. Some supporting ribs 1-4 also have a concave groove 1-7, and the groove 1-7 has a large mounting hole 1-5. It requires precise dimensions and high strength, as well as sealing requirements. Therefore, the dimensions of the product after molding are relatively high, and the sealing requirements after the flange is assembled are that it cannot leak. It is one of the important parts for the safety protection of electric vehicle electrical appliances. Because it is related to the safety of automotive electrical appliances, the requirements for the product are relatively high. The thinning rate during molding cannot exceed the standard, dark cracks cannot appear, the surface cannot wrinkle, and the flatness must meet the product tolerance. However, the size of the product itself is relatively large, with the overall length, width and thickness reaching 1341mm×1320mm×21mm. It can be seen that the length and width of the product are large, while the height is relatively small. Furthermore, the product with only 21mm must also have reinforcing ribs inside. Therefore, the depth of the reinforcing ribs inside the formed product is shallow, and the thickness of the entire product is only 0.7mm. In this way, the difficulty of forming the upper cover of the battery box of an electric vehicle is very large. Basically, the product has no strength, and the internal stress distribution is uneven after forming. The reason for this imbalance is that the main strain (the strain value of the thin plate plane in the direction of maximum elongation) and the secondary strain (the strain value of the thin plate plane perpendicular to the direction of maximum elongation) between the peripheral flange and the middle plane of the product are not balanced, and the numerical difference is large, especially the secondary strain, the numerical difference is even greater. In the prior art, the processing technology of this thin-walled large flat part usually adopts a solution of direct stretching through a forming mold in one forming, which will cause the product to be distorted very severely, with a large distortion value of up to ±50mm, and it is impossible to meet the size requirements. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a forming process for the upper cover plate of an electric vehicle battery box, which can avoid the distortion and deformation of the product after forming due to the large difference between the main and secondary strains during forming.

[0004] To solve the above technical problem, the forming process for the upper cover plate of an electric vehicle battery box provided by the present invention is as follows: after the blank plate enters the forming die assembly, four forming processes are carried out in the forming die assembly, and a set of forming dies is arranged in each forming process. The upper die assemblies of each set of forming dies are all connected to the upper die fixing plate of the forming die assembly, and the lower die assemblies of each set of forming dies are all connected to the lower die fixing plate of the forming die assembly; the four forming processes sequentially include:

[0005] 1) Stretch forming is carried out through the first forming die to obtain a semi-finished product of the first forming. The main plane, flange circumference, middle rib, branch rib and groove of the product are formed from the blank plate; moreover, before the upper die assembly closes the die, it first presses the material to form the middle rib of the product, and then after closing the die, it forms the main plane, flange circumference, branch rib and groove of the product;

[0006] 2) Primary trimming and punching are carried out through the second forming die to obtain a semi-finished product of the second forming. At this time, large mounting holes are punched in the grooves on the branch ribs, and at the same time, the contour of the product is trimmed;

[0007] 3) Secondary trimming and punching are carried out through the third forming die to obtain a semi-finished product of the third forming. At this time, small mounting holes are punched in the flange circumference, and at the same time, the contour of the product is trimmed again;

[0008] 4) Shaping is carried out through the fourth forming die to obtain the finished product. In this step, the springback phenomenon that appears in the semi-finished product of the third forming after trimming and punching is shaped to make the product trimmed to be flat.

[0009] The upper die assembly of the first forming die includes an upper die box, an upper template and a middle rib forming plate; the upper end of the upper die box is fixedly connected to the upper die fixing plate, and the upper die box is of a box structure; the upper template is connected in the upper die box, and the upper template has a receiving hole for receiving the middle rib forming plate; there is a boss on the bottom plane of the upper die box, the upper end of the middle rib forming plate is fixedly connected to the boss, and at the same time, the middle rib forming plate is located in the receiving hole of the upper template; the lower end surface of the middle rib forming plate is the forming surface of the middle rib, the lower end surface of the upper template is the forming surface of the main plane, branch rib and groove of the product, and the lower end surface of the middle rib forming plate protrudes from the lower end surface of the upper template, and the lower end surface of the upper template protrudes from the end face of the upper die box body.

[0010] There are three positioning structures at the connection between the intermediate rib forming plate and the boss of the upper die box. These three positioning structures are respectively located in the middle and at both ends of the intermediate rib forming plate. At each positioning structure, half-positioning grooves are provided on both the intermediate rib forming plate and the boss. After the intermediate rib forming plate and the boss are installed, a complete positioning groove is formed. The positioning structure is clamped in the positioning groove through a positioning strip. The positioning strip in the middle traverses the thickness of the intermediate rib forming plate, and the length direction of the positioning strips at both ends is consistent with the length direction of the intermediate rib forming plate and is located on the center line.

[0011] There are lugs at the connection between the intermediate rib forming plate and the upper die box. The lugs are multiple and are respectively arranged on both sides of the intermediate rib forming plate. Correspondingly, extension platforms matching the lugs are also provided on the boss.

[0012] In each pair of forming dies, a limiting device is provided between the upper die box and the lower die frame in the lower die assembly. The limiting device includes at least four limiting members distributed around the lower die frame. The lower end of each limiting member is connected to the lower die frame, and the upper end is located inside the upper die box.

[0013] The number of the limiting members is eight. Two limiting members are provided on each side around the lower die frame. Correspondingly, eight empty slots for the empty limiting members are provided at the lower end of the upper die box.

[0014] The limiting member includes an L-shaped horizontal block and a vertical block connected as a whole. The horizontal block is fixedly connected to the lower die frame, and the vertical block is placed in the accommodating groove of the upper die box. The side surface of the vertical block facing the inside of the die includes a lower inclined surface, an upper inclined surface, a lower flat surface, an intermediate arc surface, and an upper flat surface. Among them, the upper flat surface and the lower flat surface are connected up and down through the intermediate arc surface, the upper inclined surface and the lower inclined surface are connected up and down, and the side formed by the upper inclined surface and the lower inclined surface is connected to the side formed by the upper flat surface, the intermediate arc surface, and the lower flat surface. The other side formed by the upper flat surface, the intermediate arc surface, and the lower flat surface is connected to the side formed by another group of upper inclined surface and lower inclined surface.

[0015] After adopting the above forming process, compared with the prior art, it has the following advantages:

[0016] 1) Since after multiple forming, common problems occurring in the prior art can be effectively eliminated. In particular, the problems of distortion and cracking are optimally solved. During the forming process, the difference between the principal strain and the secondary strain is reduced, which can ensure that the product does not crack or wrinkle, and reduce distortion while ensuring that the product dimensions meet the requirements.

[0017] 2) In the one-time forming die, the entire die cavity is a sunken box structure, which reduces the difference between the principal and secondary strains to the minimum, further reducing the distortion of the product. Moreover, both the upper die and the lower die adopt movable structures. The upper die assembly first presses and forms the intermediate ribs of the product before mold closing, and then forms other features of the product after mold closing, thereby realizing the stretching process of the product.

[0018] 3) The connection between the intermediate rib forming plate and the upper die box utilizes the boss in the upper die box, featuring a simple structure, convenient processing, and low production cost. Meanwhile, the connection structure between the lug of the intermediate rib forming plate and the extension platform of the boss not only stabilizes the intermediate rib forming plate in the upper die box but also makes full use of the limited space inside the mold, with a simple structure and convenient processing.

[0019] 4) The positioning structure provided between the intermediate rib forming plate and the upper die box adopts a staggered positioning of one horizontal and two vertical directions, making the positional relationship between the intermediate rib forming plate and the upper die box more precise, thereby ensuring the dimensional accuracy of the formed product. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the part structure of the upper cover plate of the electric vehicle battery box involved in the present invention.

[0021] Figure 2 It is a schematic diagram of the structure of the one - step forming die involved in the forming process of the upper cover plate of the electric vehicle battery box of the present invention.

[0022] Figure 3 It is a schematic diagram of the partial explosion structure of the upper die in the one - step forming die of the present invention.

[0023] Figure 4 It is Figure 3 a schematic diagram of the structure of the intermediate rib forming plate and the upper die box in

[0024] Figure 5 It is a front - view structural schematic diagram of the upper die assembly in the one - step forming die of the present invention.

[0025] Figure 6 It is a schematic diagram of the structure of the limiting part in the present invention.

[0026] Wherein: 1. Upper cover plate of the electric vehicle battery box; 1 - 1. Main plane; 1 - 2. Flange circumference; 1 - 3. Intermediate rib; 1 - 4. Branch rib; 1 - 5. Large mounting hole; 1 - 6. Small mounting hole; 1 - 7. Groove; 2. Upper die box; 3. Lower die; 4. Intermediate rib forming plate; 5. Upper template; 6. Boss; 7. Accommodating hole; 8. Lug; 9. Extension platform; 10. Positioning groove; 11. Limiting part; 11 - 1. Horizontal block; 11 - 2. Vertical block; 11 - 3. Upper inclined plane; 11 - 4. Upper plane; 11 - 5. Intermediate arc surface; 11 - 6. Lower plane; 11 - 7. Lower inclined plane. Detailed Embodiments

[0027] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0028] In conjunction with Figures 1 to 6As can be seen from the schematic diagram of the die structure in the forming process of the upper cover plate of the electric vehicle battery box of the present invention, in the forming process of the upper cover plate of the electric vehicle battery box, after the blank plate enters the forming die assembly, four forming processes are carried out in the forming die assembly, and a set of forming dies is provided in each forming process. The upper die assemblies of each set of forming dies are all connected to the upper die fixing plate of the forming die assembly, and the lower die assemblies of each set of forming dies are all connected to the lower die fixing plate of the forming die assembly; the four forming processes sequentially include:

[0029] 1) Stretch forming is carried out through the first forming die to obtain a semi-finished product of the first forming. The main plane 1-1, flange perimeter 1-2, intermediate rib 1-3, branch rib 1-4, and groove 1-7 of the product are formed from the blank plate; moreover, before the upper die assembly closes the die, it first presses the material to form the intermediate rib 1-3 of the product, and then after closing the die, it forms the main plane 1-1, flange perimeter 1-2, branch rib 1-4, and groove 1-7 of the product;

[0030] 2) First trimming and punching forming is carried out through the second forming die to obtain a semi-finished product of the second forming. At this time, a large mounting hole 1-5 is punched in the groove 1-7 on the branch rib 1-4, and at the same time, the contour of the product is trimmed;

[0031] 3) Second trimming and punching forming is carried out through the third forming die to obtain a semi-finished product of the third forming. At this time, a small mounting hole 1-6 is punched on the flange perimeter, and at the same time, the contour of the product is trimmed again;

[0032] 4) Shaping forming is carried out through the fourth forming die to obtain a finished product. In this step, the springback phenomenon that appears in the semi-finished product of the third forming after trimming and punching is shaped to make the product trimmed to be flat.

[0033] The upper die assembly of the first forming die includes an upper die box 2, an upper template 5, and an intermediate rib forming plate 4; the upper end of the upper die box 2 is fixedly connected to the upper die fixing plate, and the upper die box 2 is of a box structure; the upper template 5 is connected inside the upper die box 2, and the upper template 5 has a receiving hole 7 for receiving the intermediate rib forming plate 4; there is a boss 6 on the bottom plane of the upper die box 2, the upper end of the intermediate rib forming plate 4 is fixedly connected to the boss 6, and at the same time, the intermediate rib forming plate 4 is located in the receiving hole 7 of the upper template 5; the lower end surface of the intermediate rib forming plate 4 is the forming surface of the intermediate rib 1-3, the lower end surface of the upper template 5 is the forming surface of the product main plane 1-1, branch rib 1-4, and groove 1-7, and the lower end surface of the intermediate rib forming plate 4 protrudes from the lower end surface of the upper template 5, and the lower end surface of the upper template 5 protrudes from the end face of the upper die box 2.

[0034] There are three positioning structures at the connection between the intermediate rib forming plate 4 and the boss 6 of the upper die box 2. These three positioning structures are respectively located in the middle and at both ends of the intermediate rib forming plate 4. At each positioning structure, half-positioning grooves are provided on both the intermediate rib forming plate 4 and the boss 6. After the intermediate rib forming plate 4 and the boss 6 are installed, a complete positioning groove 10 is formed. The positioning structure is clamped in the positioning groove 10 through a positioning strip. The positioning strip in the middle traverses the thickness of the intermediate rib forming plate 4, and the length directions of the positioning strips at both ends are consistent with the length direction of the intermediate rib forming plate 4 and are located on the center line.

[0035] There are lugs 8 at the connection between the intermediate rib forming plate 4 and the upper die box 2. The lugs 8 are multiple and are respectively arranged on both sides of the intermediate rib forming plate 4. Correspondingly, extension platforms 9 matching the lugs 8 are also provided on the boss 6.

[0036] In each set of forming dies, a limiting device is provided between the upper die box 2 and the lower die frame in the lower die assembly. The limiting device includes at least four limit members 11 distributed around the lower die frame. The lower end of each limit member 11 is connected to the lower die frame, and the upper end is located inside the upper die box 2.

[0037] The number of the limit members 11 is eight. Two limit members 11 are provided on each side around the lower die frame. Correspondingly, eight empty slots for accommodating the limit members 11 are provided at the lower end of the upper die box 2.

[0038] The limit member 11 includes an L-shaped horizontal block 11-1 and a vertical block 11-2 connected as a whole. The horizontal block 11-1 is fixedly connected to the lower die frame, and the vertical block 11-2 is accommodated in the accommodation groove of the upper die box 2. The side surface of the vertical block 11-2 facing the inside of the die includes a lower inclined surface 11-7, an upper inclined surface 11-3, a lower flat surface 11-6, an intermediate arc surface 11-5, and an upper flat surface 11-4. Among them, the upper flat surface 11-4 and the lower flat surface 11-6 are connected up and down through the intermediate arc surface 11-5, the upper inclined surface 11-3 and the lower inclined surface 11-7 are connected up and down, and the side formed by the upper inclined surface 11-3 and the lower inclined surface 11-7 is connected to the side formed by the upper flat surface 11-4, the intermediate arc surface 11-5, and the lower flat surface 11-6. The other side formed by the upper flat surface 11-4, the intermediate arc surface 11-5, and the lower flat surface 11-6 is connected to the side formed by another group of upper inclined surface 11-3 and lower inclined surface 11-7.

[0039] The above are only the preferred and feasible implementation examples of the present invention, and the scope of the rights of the present invention cannot be limited thereby. For those skilled in the art, all other corresponding changes made by using the technical solutions and technical concepts of the present invention should fall within the protection scope of the claims of the present invention.

Claims

1. A forming process for the upper cover plate of an electric vehicle battery box, characterized in that: After the blank plate enters the forming die assembly, four forming processes are carried out within the forming die assembly, and a set of forming dies is arranged in each forming process. The upper die assemblies of each set of forming dies are all connected to the upper die fixing plate of the forming die assembly, and the lower die assemblies of each set of forming dies are all connected to the lower die fixing plate of the forming die assembly. The four forming processes successively include: 1) Carry out stretching forming through the first forming die to obtain a semi-finished product of the first forming. The main plane (1-1), flange circumference (1-2), intermediate rib (1-3), branch rib (1-4) and groove (1-7) of the product are formed from the blank plate. Moreover, before the upper die assembly closes the die, it first presses the material to form the intermediate rib (1-3) of the product, and then after closing the die, it forms the main plane (1-1), flange circumference (1-2), branch rib (1-4) and groove (1-7) of the product; 2) Carry out primary trimming and punching forming through the second forming die to obtain a semi-finished product of the second forming. At this time, large mounting holes (1-5) are punched in the grooves (1-7) on the branch ribs (1-4), and at the same time, the contour of the product is trimmed; 3) Carry out secondary trimming and punching forming through the third forming die to obtain a semi-finished product of the third forming. At this time, small mounting holes (1-6) are punched on the flange circumference, and at the same time, the contour of the product is trimmed again; 4) Carry out sizing forming through the fourth forming die to obtain a finished product. In this step, the springback phenomenon that appears in the semi-finished product of the third forming after trimming and punching is sized to make the product trimmed to be flat.

2. The forming process of the upper cover plate of the electric vehicle battery box according to claim 1, characterized in that: The upper die assembly of the first forming die includes an upper die box (2), an upper template (5) and an intermediate rib forming plate (4); the upper end of the upper die box (2) is fixedly connected to the upper die fixing plate, and the upper die box (2) is of a box structure; the upper template (5) is connected inside the upper die box (2), and the upper template (5) has a receiving hole (7) for receiving the intermediate rib forming plate (4); there is a boss (6) on the bottom plane of the upper die box (2), the upper end of the intermediate rib forming plate (4) is fixedly connected to the boss (6), and at the same time, the intermediate rib forming plate (4) is located in the receiving hole (7) of the upper template (5); the lower end face of the intermediate rib forming plate (4) is the forming surface of the intermediate rib (1-3), the lower end face of the upper template (5) is the forming surface of the main plane (1-1), branch rib (1-4) and groove (1-7) of the product, and the lower end face of the intermediate rib forming plate (4) protrudes from the lower end face of the upper template (5), and the lower end face of the upper template (5) protrudes from the end face of the box body of the upper die box (2).

3. The forming process of the upper cover plate of the electric vehicle battery box according to claim 2, characterized in that: Three positioning structures are provided at the connection between the intermediate rib forming plate (4) and the boss (6) of the upper die box (2). The three positioning structures are respectively located in the middle and at both ends of the intermediate rib forming plate (4). Semi-positioning grooves are provided on both the intermediate rib forming plate (4) and the boss (6) at each positioning structure. After the intermediate rib forming plate (4) and the boss (6) are installed, a complete positioning groove (10) is formed. The positioning structure is clamped in the positioning groove (10) through a positioning bar. The positioning bar in the middle traverses the thickness of the intermediate rib forming plate (4), and the length directions of the positioning bars at both ends are consistent with the length direction of the intermediate rib forming plate (4) and are located on the center line.

4. The forming process of the upper cover plate of the electric vehicle battery box according to claim 2, characterized in that: Lugs (8) are provided at the connection between the intermediate rib forming plate (4) and the upper die box (2). There are multiple lugs (8), which are respectively arranged on both sides of the intermediate rib forming plate (4). Correspondingly, extension platforms (9) matching the lugs (8) are also provided on the boss (6).

5. The forming process of the upper cover plate of the electric vehicle battery box according to claim 1, characterized in that: In each set of forming dies, a limiting device is provided between the upper die box (2) and the lower die frame in the lower die assembly. The limiting device includes at least four limiting members (11) distributed around the lower die frame. The lower end of each limiting member (11) is connected to the lower die frame, and the upper end is located inside the upper die box (2).

6. The forming process of the upper cover plate of the electric vehicle battery box according to claim 5, characterized in that: The number of the limiting members (11) is eight. Two limiting members (11) are provided on each side around the lower die frame. Correspondingly, eight empty slots for the empty limiting members (11) are provided at the lower end of the upper die box (2).

7. The forming process of the upper cover plate of the electric vehicle battery box according to claim 6, characterized in that: The limiting member (11) includes an L-shaped horizontal block (11-1) and a vertical block (11-2) connected as a whole. The horizontal block (11-1) is fixedly connected to the lower die frame, and the vertical block (11-2) is placed in the accommodation groove of the upper die box (2). The side surface of the vertical block (11-2) facing the inside of the die includes a lower inclined surface (11-7), an upper inclined surface (11-3), a lower flat surface (11-6), an intermediate arc surface (11-5) and an upper flat surface (11-4). Among them, the upper flat surface (11-4) and the lower flat surface (11-6) are connected up and down through the intermediate arc surface (11-5), the upper inclined surface (11-3) and the lower inclined surface (11-7) are connected up and down, and the side formed by the upper inclined surface (11-3) and the lower inclined surface (11-7) is connected to the side formed by the upper flat surface (11-4), the intermediate arc surface (11-5) and the lower flat surface (11-6). The other side formed by the upper flat surface (11-4), the intermediate arc surface (11-5) and the lower flat surface (11-6) is connected to the side formed by another set of upper inclined surface (11-3) and lower inclined surface (11-7).

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