Lightweight battery case lower protective plate and manufacturing method thereof

Abstract

The invention relates to the technical field of battery case lower protective plates, in particular to a lightweight battery case lower protective plate and a manufacturing method thereof, and the lower protective plate comprises a first main body, a second main body and a connecting plate; the first main body and the second main body are symmetrically arranged at two ends of the connecting plate; each of the first main body and the second main body comprises a main plate, two first reinforcing plates, a second reinforcing plate, a third reinforcing plate and a plurality of reinforcing blocks; wherein the first reinforcing plate, the second reinforcing plate and the plurality of reinforcing blocks are arranged on the first surface of the main plate; the other first reinforcing plate is positioned on the second surface of the main plate; the plurality of reinforcing blocks are positioned between the first reinforcing plate and the second reinforcing plate; the third reinforcing plate is arranged on the edge of the main plate and is opposite to the connecting plate. The battery lower protection plate has the advantages that the battery lower protection plate is manufactured by adopting various continuous glass fiber reinforced PP composite materials through the processes of material compounding, heating, hot press molding, trimming and punching, bushing assembling and the like, so that the manufacturing cost is reduced, and the production efficiency is also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of the lower guard plate of a battery case, and particularly relates to a lightweight lower guard plate of a battery case and a manufacturing method thereof. Background Art

[0002] In recent years, some vehicle manufacturers have used GFK (thermosetting resin-infiltrated glass fiber unidirectional fabric) and LFI materials (resin and glass fiber mixed injection materials) to manufacture the lower guard plate of a new energy vehicle battery case through a wet compression molding technology. This process has the following disadvantages: 1) There are too many production processes and large investments. 2) The hot pressing molding cycle of thermosetting materials is about 300 seconds to 480 seconds, and the production efficiency is low. 3) After molding, mechanical processing methods such as trimming and milling holes are required, increasing the production time and cost; 4) The single-line production capacity cannot meet mass production. 5) The plasticity is poor, and it is difficult to form complex geometric structures; 6) The sound absorption and noise reduction performance is poor. 7) Thermosetting materials are non-renewable and not environmentally friendly. Summary of the Invention

[0003] In view of this, the present invention aims to provide a lightweight lower guard plate of a battery case and a manufacturing method thereof. By using a variety of continuous glass fiber-reinforced PP (polypropylene) composite materials, the lower guard plate of the battery case is manufactured through processes such as material compounding, heating, hot pressing molding, trimming and punching, and assembling bushings, which can reduce the manufacturing cost, improve the production efficiency, and further reduce the weight.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows: A lightweight lower guard plate of a battery case includes a first main body, a second main body, and a connecting plate; the first main body and the second main body are symmetrically arranged at both ends of the connecting plate; the first main body and the second main body have the same structure, and both include a main board, a second reinforcing plate, a third reinforcing plate, two first reinforcing plates, and a plurality of reinforcing blocks; wherein, the two first reinforcing plates are respectively arranged on two opposite surfaces of the main board and are corresponding in position; the second reinforcing plate and the plurality of reinforcing blocks are jointly arranged on the first surface of the main board with one of the first reinforcing plates; the third reinforcing plate is arranged at the edge of the main board, and the third reinforcing plate is opposite to the connecting plate.

[0005] Further, the material of the main board is LWRT; the materials of the two first reinforcing plates are UD-TAPE.

[0006] Further, the materials of the second reinforcing plate and the plurality of reinforcing blocks are both LWRT with PO Film.

[0007] Further, the connecting plate includes a first connecting plate and a second connecting plate; wherein, the first connecting plate is located on the same side of the first surface of the main board, and the second connecting plate is located on the same side of the second surface opposite to the first surface; the material of the first connecting plate is UD-TAPE, and the material of the second connecting plate is GMT.

[0008] Further, the first main body, the second main body, and the connecting plate are integrally formed by a hot pressing process.

[0009] Further, it further includes a plurality of bushings, and the plurality of bushings are respectively arranged on the third reinforcing plate and the connecting plate.

[0010] Further, the number of the reinforcing blocks is three, and the three reinforcing blocks are arranged in a pin shape on the first surface of the main board.

[0011] A manufacturing method for a lightweight battery case lower guard plate for manufacturing the above-mentioned lightweight battery case lower guard plate. The battery case lower guard plate includes a first main body, a second main body, and a connecting plate; the first main body and the second main body have the same structure, and both include a main board, a second reinforcing plate, a third reinforcing plate, two first reinforcing plates, and a plurality of reinforcing blocks; the connecting plate includes a first connecting plate and a second connecting plate; the method includes the following steps: S1: Pre-connect the second reinforcing plate, the two first reinforcing plates, and the plurality of reinforcing blocks to the main board corresponding to the first main body to form a first main body preform; pre-connect the second reinforcing plate, the two first reinforcing plates, and the plurality of reinforcing blocks to the main board corresponding to the second main body to form a second main body preform; at the same time, pre-connect the first connecting plate and the second connecting plate to form a connecting plate preform.

[0012] S2: Heat the first main body preform, the second main body preform, the connecting plate preform, and the two third reinforcing plates.

[0013] S3: Place the heated first main body preform, second main body preform, connecting plate preform, and the two third reinforcing plates into a forming mold, and perform hot pressing and integral forming to form a battery case lower guard plate preform.

[0014] S4: Trim the battery case lower guard plate preform and punch installation holes.

[0015] S5: Assemble the bushings into the installation holes to complete the manufacturing of the battery case lower guard plate.

[0016] Further, in step S1, the pre-connection is achieved by ultrasonic spot welding.

[0017] Further, the heating temperature of the first main body preform and the second main body preform is a first preset temperature; the heating temperature of the connecting plate preform and the third reinforcing plate is a second preset temperature; the first preset temperature is lower than the second preset temperature.

[0018] The present invention can achieve the following beneficial effects: The present invention uses a variety of continuous glass fiber reinforced polypropylene composites to manufacture the battery lower guard plate through processes such as material compounding, heating, hot pressing, trimming, punching, and assembling bushings, which not only reduces the manufacturing cost but also improves the production efficiency. The hot pressing process of thermoplastic materials has the characteristics of short production cycle and high efficiency. After molding, trimming and punching are carried out by stamping equipment, and a single line can meet the large-scale production requirements. LWRT (Low Weight Reinforced Thermoplastic) and GMT (Glass Mat Reinforced Thermoplastics) materials have excellent plasticity and the forming performance of complex geometric structures. The parts can achieve unequal thickness design, such as the thickness of the compaction area is 2mm, and the thickness of the sound absorption and noise reduction part is 5-7mm to meet the requirements of sound absorption and noise reduction performance. At the same time, UD-TAPE (Unidirectional Tape) and LWRT with PO Film (a composite material combining LWRT and PO Film (polyolefin film)) materials are used locally for reinforcement to ensure mechanical properties. In addition, this process further realizes lightweight, and the weight of the parts is reduced by about 35-40% compared with GFK and LFI materials BRIEF DESCRIPTION OF THE DRAWINGS The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 is a schematic structural diagram of a lightweight battery case lower guard plate provided according to an embodiment of the present invention; Figure 2 is a schematic structural diagram of ultrasonic welding of a main board, a first reinforcing plate, a second reinforcing plate, a reinforcing block, and a connecting plate provided according to an embodiment of the present invention; Figure 3 is a schematic structural diagram of hot pressing of a main board, a first reinforcing plate, a second reinforcing plate, a third reinforcing plate, a reinforcing block, and a connecting plate provided according to an embodiment of the present invention; Figure 4 is provided according to an embodiment of the present invention Figure 1 is a cross-sectional view of hot pressing of the third reinforcing plate and the main board at A-A in; Figure 5 is provided according to an embodiment of the present invention Figure 1 is a cross-sectional view of hot pressing of the second reinforcing plate, the reinforcing block, and the main board at B-B in; Figure 6 is provided according to an embodiment of the present invention Figure 1 is a cross-sectional view of hot pressing of the first reinforcing plate and the main board at C-C in; Figure 7 is a cross-sectional view of the connection plate and the main board at D-D in the heat pressing and forming according to the embodiment of the present invention. Figure 1 in the heat pressing and forming of the connection plate and the main board at D-D.

[0019] The reference numerals include: 1, the first main body; 11, the main board; 12, the first reinforcing plate; 13, the second reinforcing plate; 14, the third reinforcing plate; 15, the reinforcing block; 2, the second main body; 3, the connection plate; 4, the bushing. Detailed implementation manners

[0020] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further details the present invention in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0021] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "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 drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0024] The following will detail the present invention in conjunction with the embodiments.

[0025] As Figures 1 to 7As shown in the figure, a lightweight battery case lower guard plate provided by an embodiment of the present invention includes a first main body 1, a second main body 2, a connecting plate 3, and a plurality of bushings 4. The first main body 1 and the second main body 2 are symmetrically arranged at both ends of the connecting plate 3. The plurality of bushings 4 are arranged on the first main body 1, the second main body 2, and the connecting plate 3. The bushings 4 are used to increase the installation strength and play a protective role.

[0026] The first main body 1 and the second main body 2 have the same structure, and both include a main board 11, two first reinforcing plates 12, a second reinforcing plate 13, a third reinforcing plate 14, and a plurality of reinforcing blocks 15. Among them, one first reinforcing plate 12, one second reinforcing plate 13, and a plurality of reinforcing blocks 15 are all arranged on the first surface of the main board 11. The other first reinforcing plate 12 is located on the second surface of the main board 11. The two first reinforcing plates 12 are on two opposite surfaces of the main board 11 and are correspondingly positioned. The plurality of reinforcing blocks 15 are located between the first reinforcing plate 12 and the second reinforcing plate 13. The third reinforcing plate 14 is arranged at the edge of the main board 11 opposite to the connecting plate 3. Mounting holes adapted to the bushings 4 are respectively arranged on the third reinforcing plate 14 and the connecting plate 3. The bushings 4 are press-fitted into the mounting holes.

[0027] The number of the reinforcing blocks 15 and the bushings 4 is determined by the number of parts that the battery case lower guard plate needs to connect. In this embodiment, the number of the reinforcing blocks 15 is three, and the three reinforcing blocks 15 are arranged in a triangular pattern on the first surface of the main board 11. Six mounting holes are arranged on each third reinforcing plate 14, and one mounting hole is arranged on the connecting plate 3. The number of the bushings 4 is 13.

[0028] In other embodiments, the number of the reinforcing blocks 15 is two, or greater than 3.

[0029] The material of the main board 11 is LWRT (Low Weight Reinforced Thermoplastic). In this embodiment, LWRT is made of polypropylene-based chopped glass fibers, and the upper surface is covered with polyester non-woven fabric to form a laminate structure. Among them, the glass fiber content is 30%, and the rest is polypropylene matrix. The areal density of LWRT is 1400 g / m 2 , which not only meets the mechanical property requirements but also has sound absorption and noise reduction performance. The initial thickness of the LWRT laminate is 4 mm, and it can fluff up to 10 mm after heating.

[0030] The material of the first reinforcing plate 12 is UD-TAPE (Unidirectional Tape). In this embodiment, UD-TAPE is made of polypropylene-based glass fiber unidirectional cloth to form a laminate structure. Among them, the glass fiber content is 70%, and the rest is polypropylene matrix. The thickness of the first reinforcing plate 12 is 0.75 mm.

[0031] The materials of the second reinforcement plate 13 and the multiple reinforcement blocks 15 are both LWRT with PO Film (a composite material combining LWRT and PO Film (polyolefin film)). In this embodiment, LWRT with PO Film is made of polypropylene-based chopped glass fibers, and the upper and lower surfaces are covered with PO Film to form a laminate structure. This material has good tensile strength and tear strength properties, and at the same time has a high degree of compatibility with the LWRT material of the main board 11. Among them, the glass fiber content in LWRT with PO Film is 25%, and the rest is polypropylene matrix. The areal density of LWRT with PO Film is 1200g / m 2 . The initial thickness of the LWRT with PO Film laminate is 1.25mm and it can fluff up to 4mm after heating.

[0032] The material of the third reinforcement plate 14 is GMT (Glass Mat Reinforced Thermoplastics). In this embodiment, GMT is made of polypropylene-based glass fiber mat to form a laminate structure. Among them, the glass fiber content is 50%, and the rest is polypropylene matrix. GMT has excellent mechanical properties, fluidity and higher thermal stability. The initial thickness of the GMT laminate is 4.8mm and it can fluff up to 10mm after heating.

[0033] The connecting plate 3 includes a first connecting plate and a second connecting plate. The first connecting plate is on the same side of the first surface of the main board 11, and the second connecting plate is on the same side of the second surface opposite to the first surface. The material of the first connecting plate is UD-TAPE with a thickness of 0.75mm. The material of the second connecting plate is GMT. In this embodiment, GMT is made of polypropylene-impregnated glass fiber mat to form a laminate structure. Among them, the glass fiber content is 50%, and the rest is polypropylene matrix. GMT has excellent mechanical properties, fluidity and higher thermal stability. The initial thickness of the GMT laminate is 4.8mm and it can fluff up to 10mm after heating.

[0034] The first main body 1, the second main body 2 and the connecting plate 3 are hot-pressed and formed. In this embodiment, by utilizing the heating and fluffing characteristics of LWRT, the lower guard plate of the battery case adopts a non-uniform thickness structure, and is divided into a compacted area and a non-compacted area after hot-pressing and forming. The compacted area is the area of the first reinforcement plate 12, the second reinforcement plate 13, the third reinforcement plate 14 and the reinforcement blocks 15 on the main board 11, and the area where the connecting plate 3 is located.

[0035] Compaction zone: It mainly plays the role of increasing strength and has a thickness of 2 mm. Since UD-TAPE, LWRT, and GMT all contain polypropylene components, the materials are in a molten state after heating. Under the action of the forming pressure, the first reinforcing plate 12, the second reinforcing plate 13, the third reinforcing plate 14, and multiple reinforcing blocks 15 are pressed and integrated with the main board 11. The first connecting plate and the second connecting plate are pressed and integrated. At the same time, the GMT material has good fluidity and filling performance, and penetrates into the LWRT material of the main board 11 under the action of the forming pressure, and is fused and connected with the main board 11, so that the third reinforcing plate 14 and the main board 11 are combined into one body, and the connecting plate 3 and the first main body 1, the second main body 2 are combined into one body.

[0036] Non-compaction zone: It has the function of sound absorption and noise reduction and has a thickness of 5 - 7 mm. The LWRT material of the main board 11 can fluff up to 10 mm after heating, and the mold is designed according to the product structure. The thickness of the non-compaction zone during forming is realized by the mold.

[0037] A manufacturing method of a lightweight battery case lower guard plate is used to manufacture the above-mentioned lightweight battery case lower guard plate. The battery case lower guard plate includes a first main body, a second main body, and a connecting plate; the first main body and the second main body have the same structure, and both include a main board, a second reinforcing plate, a third reinforcing plate, two first reinforcing plates, and multiple reinforcing blocks; the connecting plate includes a first connecting plate and a second connecting plate; the method includes the following steps: S1: Pre-connect the second reinforcing plate 13, two first reinforcing plates 12, and multiple reinforcing blocks 15 to the corresponding main board 11 of the first main body 1 by ultrasonic spot welding to form a first main body preform. Pre-connect the second reinforcing plate 13, two first reinforcing plates 12, and multiple reinforcing blocks 15 to the corresponding main board 11 of the second main body 2 by ultrasonic spot welding to form a second main body preform; at the same time, pre-connect the first connecting plate and the second connecting plate by ultrasonic spot welding to form a connecting plate preform.

[0038] Specifically, place two first reinforcing plates 12, one second reinforcing plate 13, multiple reinforcing blocks 15, and one main board 11 of the first main body 1 at the corresponding positions of the ultrasonic welding machine mold. Place two first reinforcing plates 12, one second reinforcing plate 13, multiple reinforcing blocks 15, and one main board 11 of the second main body 2 at the corresponding positions of the ultrasonic welding machine mold. At the same time, place the first connecting plate and the second connecting plate at the corresponding positions of the ultrasonic welding machine mold. Start the ultrasonic welding machine, and pre-connect two first reinforcing plates 12, one second reinforcing plate 13, and multiple reinforcing blocks 15 to their respective main boards 11 to form a first main body preform and a second main body preform. At the same time, pre-connect the first connecting plate and the second connecting plate by ultrasonic spot welding to form a connecting plate preform.

[0039] In this embodiment, the wave frequency specification of the ultrasonic system of the ultrasonic welder is 35KHZ, and the manufacturer is: Tianjin Aisuo Precision Machinery Co., Ltd.

[0040] The ultrasonic welder can weld thin UD-TAPE laminates (the first reinforcement plate 12), LWRT with PO Film laminates (the second reinforcement plate 13 and the reinforcement block 15), and GMT laminates (the second connecting plate). Since the UD-TAPE laminate, LWRT with PO Film laminate, and GMT laminate all contain polypropylene components, the temperature during welding by the ultrasonic welder can keep the materials in a molten state, thus realizing the welding of the first reinforcement plate 12, the second reinforcement plate 13, and the reinforcement block 15 to the main board 11, as well as the welding of the first connecting plate and the second connecting plate.

[0041] In this embodiment, the cross-section of the welding head of the ultrasonic welder has a reticulated structure, which can realize the welding of UD-TAPE laminates, LWRT with PO Film laminates, and GMT laminates with a thickness of less than 2mm. In other embodiments, if it is necessary to weld UD-TAPE laminates, LWRT with PO Film laminates, and GMT laminates with a thickness greater than 2mm, a welding head with a needle-shaped cross-section is used, and an appropriate wave frequency needs to be adjusted.

[0042] S2: Heat the first main body preform, the second main body preform, the connecting plate preform, and the two third reinforcement plates 14.

[0043] Specifically, a heating furnace is used to heat the first main body preform, the second main body preform, the connecting plate preform, and the two third reinforcement plates 14. Place the first main body preform and the second main body preform in a heating chamber of the heating furnace, with a heating temperature of 235°C (the first preset temperature) and a heating time of 50 seconds to 55 seconds. Place the connecting plate 3 and the two third reinforcement plates 14 in another heating chamber of the heating furnace, with a heating temperature of 265°C (the second preset temperature) and a heating time of 50 seconds to 55 seconds. The first main body preform, the second main body preform, the connecting plate preform, and the two third reinforcement plates 14 are removed from the heating furnace simultaneously.

[0044] S3: Place the heated first main body preform, the second main body preform, the connecting plate preform, and the two third reinforcement plates 14 into a forming mold and perform hot pressing and integral forming to form a preform of the lower battery case guard.

[0045] Use a hot press to perform hot pressing and integral forming on the first main body preform, the second main body preform, the connecting plate preform, and the two third reinforcement plates 14. The forming pressure is 1500T, and the hot pressing and forming time is 25 seconds to 30 seconds, among which the pressure holding and cooling time is 10 seconds to 12 seconds.

[0046] After the first main body preform and the second main body preform are hot-pressed and formed, the thickness of the compacted area of the first main body preform and the second main body preform is 2 mm, and the thickness of the sound absorption and noise reduction part is 5-7 mm, which can meet the sound absorption and noise reduction performance.

[0047] S4: Trim the preform of the lower battery case guard and punch the mounting holes.

[0048] Trimming and punching are carried out on a stamping device, and the punching force is about 950 KN. S5: Assemble the bushing 4 into the mounting hole to complete the manufacture of the lower battery case guard.

[0049] In this embodiment, it is realized by an existing semi-automatic press-fitting tooling, and two standard electric cylinders with a rated output of 1500 N and a power of 400 W are used for press-fitting.

[0050] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A lightweight battery shell lower guard plate, characterized in that: It comprises a first body, a second body and a connecting plate; the first body and the second body are symmetrically arranged at two ends of the connecting plate; The first main body and the second main body have the same structure, and both include a main board, a second reinforcement plate, a third reinforcement plate, two first reinforcement plates and a plurality of reinforcement blocks; wherein the two first reinforcement plates are respectively arranged on two opposite surfaces of the main board, and the positions are corresponding; the second reinforcement plate and the plurality of reinforcement blocks are arranged together with one of the first reinforcement plates on the first surface of the main board; the third reinforcement plate is arranged at the edge of the main board, and the third reinforcement plate is opposite to the connecting plate.

2. The lightweight battery housing lower guard plate according to claim 1, characterized in that: The material of the main board is LWRT; the material of the two first reinforcement boards is UD-TAPE.

3. The lightweight battery housing lower guard plate according to claim 1, characterized in that: The second reinforcing plate and the plurality of reinforcing blocks are made of LWRT with PO Film.

4. The lightweight battery housing lower guard plate according to claim 1, characterized in that: The connecting plate comprises a first connecting plate and a second connecting plate; wherein the first connecting plate is located on the same side of the first surface of the main board, and the second connecting plate is located on the same side of the second surface opposite to the first surface; The material of the first connecting plate is UD-TAPE, and the material of the second connecting plate is GMT.

5. The lightweight battery housing lower guard plate according to claim 1, characterized in that: The first body, the second body and the connecting plate are integrally formed by a hot pressing process.

6. The lightweight battery housing lower guard plate according to claim 1, characterized in that: It also includes a plurality of bushings, which are respectively arranged on the third reinforcing plate and the connecting plate.

7. The lightweight battery housing lower guard plate according to claim 1, characterized in that: The number of the reinforcement blocks is three, and the three reinforcement blocks are arranged on the first surface of the main board in a herringbone shape.

8. A method for manufacturing a lightweight battery shell lower guard plate, used to manufacture the lightweight battery shell lower guard plate according to any one of claims 1 to 7, the battery shell lower guard plate comprising a first main body, a second main body and a connecting plate; the first main body and the second main body have the same structure, both comprising a main board, a second reinforcing plate, a third reinforcing plate, two first reinforcing plates and a plurality of reinforcing blocks; the connecting plate comprises a first connecting plate and a second connecting plate; characterized in that, The steps include: S1: pre-connecting the second reinforcing plate, two first reinforcing plates and a plurality of reinforcing blocks with the main board corresponding to the first main body to form a first main body preform; pre-connecting the second reinforcing plate, two first reinforcing plates and a plurality of reinforcing blocks with the main board corresponding to the second main body to form a second main body preform; and at the same time, pre-connecting the first connecting plate and the second connecting plate to form a connecting plate preform; S2: heating the first main body preform, the second main body preform, the connecting plate preform and the two third reinforcing plates; S3: placing the heated first main body preform, the second main body preform, the connecting plate preform and the two third reinforcing plates into a forming mold, and hot pressing and integrally forming them to form a battery shell lower guard plate preform; S4: trimming the battery housing lower guard plate preform and punching mounting holes; S5: Assemble the bushing into the mounting hole to complete the manufacture of the lower guard plate of the battery shell.

9. The method for manufacturing a lightweight battery housing lower guard plate according to claim 8, characterized in that: In step S1, the pre-connection is achieved by ultrasonic spot welding.

10. The method for manufacturing a lightweight battery housing lower guard plate according to claim 8, characterized in that: The heating temperature of the first main body preform and the second main body preform is a first preset temperature; the heating temperature of the connecting plate preform and the third reinforcing plate is a second preset temperature; the first preset temperature is lower than the second preset temperature.

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