Thermoplastic new energy automobile battery cover forming method

Abstract

The invention belongs to the technical field of new energy automobile battery cover forming, particularly relates to a thermoplastic new energy automobile battery cover forming method, and provides a thermoplastic new energy automobile battery cover forming method. A fiber cloth prepreg is used as a material, engineering plastics and the like are used as a prepreg matrix, and a qualified product is finally obtained through preparation of a resin sheet / glass fiber cloth, compounding of the prepreg by a double-belt press, transverse cutting / longitudinal cutting of the fiber cloth prepreg, pre-shearing of the fiber cloth prepreg, local reinforcement, spreading, heating in a drying oven, compression molding and the like, and after post-processing, detection and the like. The battery cover product formed by the process is green, recoverable, excellent in mechanical property and large in lightweight potential, does not burn through after being burnt by flames for 1 hour, passes UL 94 V-0 certification and has very high flame retardant property, and a client passes a battery cell thermal runaway test.

Description

Technical Field

[0001] The present invention belongs to the technical field of the formation of new energy vehicle battery covers, and particularly relates to a method for forming a thermoplastic new energy vehicle battery cover. Background Art

[0002] Currently, the field of new energy vehicles remains a hot area for national development, and the new energy vehicle PACK is the core component of new energy vehicles. As the covering part of PACK, the forming process and materials of the battery cover have always been the focus of composite material research and development. Currently, the processes used for battery covers include sheet metal stamping, PCM, SMC, high-pressure RTM, etc. Sheet metal stamping is relatively heavy and has a greater impact on the vehicle mileage. Due to the cracking problem of the SMC process battery cover that has never been solved, SMC only maintains existing projects and no new projects are developed, and it is very likely to be eliminated from the new energy vehicle market. The PCM process battery cover has high overall strength and few cracking problems, and it is the process mainly promoted by Guoxuan High-Tech recently. However, the PCM process requires a lot of labor and has many post-treatment problems, resulting in low profits for the PCM process battery cover. Similarly, the high-pressure RTM process has a large investment, and there are still many problems with the high-pressure RTM process at present, such as the localization of resin and the consumption of injection nozzles. The above composite material processes (SMC / PCM / high-pressure RTM) are all thermosetting processes and have the disadvantage of being non-recyclable.

[0003] Currently, it is particularly important to comprehensively improve the level of the recycling and utilization ability of power batteries. At the same time, green design of power batteries is proposed to lead and drive recycling and utilization. Therefore, higher requirements are put forward for the recyclability of battery covers.

[0004] The continuous fiber thermoplastic composite material battery cover is a thermoplastic material, which is green and recyclable. At the same time, it has excellent high strength, high modulus, flame retardancy and fire resistance, and should be the best solution for battery covers. The continuous glass fiber reinforced composite material includes two directions: continuous fiber prepreg tapes and fiber cloth prepregs. Summary of the Invention

[0005] The present invention provides a method for forming a thermoplastic new energy vehicle battery cover to solve the problems pointed out in the background art.

[0006] A method for forming a thermoplastic new energy vehicle battery cover includes the following steps: a. Fix a layer of resin film, a layer of fiber cloth, and a layer of resin film on a double-belt press as required, start the double-belt press, and process it into a fiber cloth prepreg with a fiber content of 65-70%; b. Cut the fiber cloth prepreg obtained in step a into sheets of target size through a cross cutter and a longitudinal cutter; c. Unfold the three-dimensional model of the battery cover into a two-dimensional shape to form pre-cutting data, and then input the data into the processing system of the fabric cutting machine to form the shape to be cut. Place the sheet obtained in step b on the fabric cutting machine for pre-cutting of the sheet; d. According to the design requirements, use fiber-reinforced sheets of a certain size to perform local reinforcement on the positions that need to be strengthened, and prepare a certain number and size of reinforcement sheets; e. Place the pre-cut sheet obtained in step c on the tooling on one side of the tunnel furnace, and then place the reinforcement sheet on the target position of the pre-cut sheet to complete the laying of the material; f. Start the conveyor belt of the tunnel furnace, input the sheet with the laid material into the furnace for heating for 10 - 30 seconds. After heating is completed, send it to the mold on the press; g. Open the laying tooling, lay the heated sheet on the mold, and the laying tooling returns to its original position. At this time, the press closes the mold to perform the molding process of the sheet, and the pressure holding time is 45 - 75 seconds; h. Open the mold of the press, take out the battery cover product, perform post-treatment and inspection to complete the entire process of pressing the battery cover product.

[0007] Preferably, the resin sheet in step a is PA engineering plastic, or PC engineering plastic, or PP general-purpose plastic, or PPS engineering plastic, or PEEK engineering plastic.

[0008] Preferably, the fiber cloth in step a is one or a combination of two of glass fiber and carbon fiber.

[0009] Preferably, the fiber cloth in step a is an alkali-free glass fiber cloth or a carbon fiber cloth treated with a coupling agent.

[0010] Preferably, the double-belt press in step a is a Teflon double-belt continuous press or a double-steel-belt continuous press.

[0011] Preferably, the fabric cutting machine in step c is a composite material cutting machine with tungsten carbide blades for one-key cutting of materials.

[0012] Preferably, the glass fiber reinforced sheet in step d is formed by an injection molding process or a molding process, the glass fiber content is 30 - 50%, and the matrix of the reinforcement sheet is the same as the matrix material of the main body.

[0013] Preferably, the tunnel furnace in step e / f uses carbon fiber heating tubes, ceramic heating tubes or infrared heating, and adopts a single-layer or double-layer design.

[0014] Preferably, the time from the completion of sheet heating to the closing of the press mold needs to be controlled within 15 seconds to avoid heat loss of the sheet due to too long a time, which affects product pressing.

[0015] Preferably, the mold in step g is a cold mold, and the mold temperature controller keeps the mold temperature at 40-120 degrees Celsius.

[0016] Beneficial effects: The present invention provides a method for forming a thermoplastic new energy vehicle battery cover; fiber cloth prepreg is used as the material, and engineering plastics, etc. are used as the prepreg matrix. After resin sheet / glass fiber cloth preparation, double-belt press composite prepreg, cross-cutting / longitudinal cutting of fiber cloth prepreg, pre-shearing of fiber cloth prepreg, local reinforcement, laying, oven heating, compression molding, etc., and finally through post-processing, inspection, etc., a qualified product is obtained. The battery cover product formed by this process is green and recyclable, has excellent mechanical properties, great potential for lightweight, does not burn through after 1 hour of flame burning, passes the UL 94 V-0 certification, has very high flame retardant performance, and the client passes the thermal runaway test of the battery cell. Description of the Drawings

[0017] Figure 1 is a schematic process flow diagram of the present invention, Detailed Embodiments

[0018] The following combines the drawings to describe in detail a specific embodiment of the present invention, but it should be understood that the protection scope of the present invention is not limited by the specific embodiment.

[0019] Example 1: As Figure 1 shown, (1) Resin sheet / glass fiber cloth preparation: The resin sheet is Shanghai Kaisai Bio-based Polyamide Ecopent® 2260, with a resin viscosity of 2.6, a thickness of 0.25 mm, a width of 1.2 m, and a continuous resin sheet.

[0020] The glass fiber cloth is Chongqing International Fine Yarn Industrial Cloth 3784, with an 8-harness satin weave, a thickness of 1.0 mm, a width of 1.2 m, and fireproof and protective properties.

[0021] (2) Double-steel-belt continuous press composite prepreg: Place the resin sheet and the glass fiber cloth at fixed positions on the double-Teflon-belt press. The processing temperature is 275-290 °C, the pressure is 2.5-3.5 Bar, and the designed glass fiber content is 65%. Turn on the double-steel-belt continuous press to obtain the glass fiber cloth prepreg, with a prepreg thickness of 1.2 mm and a width of 1.2 m.

[0022] (3) Cross-cutting of fiber cloth prepreg: Use a cross-cutting machine to cut the prepreg into fixed-length prepreg plates with a length of 1.2 m.

[0023] (4) Pre-shearing of fiber cloth prepreg: Unfold the three-dimensional model of the battery cover into a two-dimensional shape to form pre-shearing data, and then input the data into the processing system of the cloth cutting machine to form the shape to be cut. Place the 1.2 m * 1.2 m prepreg plate on the cloth cutting machine for pre-shearing of the sheet. The cloth cutting machine is a composite material cutting machine with tungsten carbide blades for one-key cutting of the material.

[0024] (5) Local reinforcement: According to the design requirements, fiber-reinforced sheets of a certain size are used to locally reinforce the flange position and interface position of the battery cover, and a certain number and size of reinforcement sheets are prepared. The fiber-reinforced sheet is a short glass fiber-reinforced polyamide sheet formed by injection molding, with a fiber content of 40%, a thickness of 1.2 mm, and a width of 25 mm. The flange of the reinforcement sheet is arranged with one horizontal and one vertical strip, a total of 4 strips, with a horizontal length of 1200 mm and a vertical length of 1175 mm. The interface of the reinforcement sheet is arranged with one strip for each of the 4 interfaces, with a length of 40 mm.

[0025] (6) Laying materials: Place the pre-cut sheet on the tooling on one side of the tunnel furnace, and then place the reinforcement sheet at the target position of the pre-cut sheet to complete the laying of materials.

[0026] (7) Oven heating: Start the conveyor belt of the tunnel furnace, input the sheet after laying materials into the furnace for heating. The tunnel furnace uses infrared heating, with a heating temperature of 285 °C for 15 seconds. After heating is completed, it is sent to the mold on the press.

[0027] (8) Compression molding: Open the laying tooling, place the heated sheet on the mold, and the laying tooling returns to its original position. At this time, the press closes the mold, requiring a mold closing time of 10 seconds. During the compression molding process of the sheet, the holding pressure time is 60 seconds and the pressure is 1000 tons.

[0028] (9) Post-processing and inspection: Open the mold of the press, and use a manipulator or manually take out the battery cover product for post-treatment and inspection to complete the entire process of pressing the battery cover product.

[0029] Example 2: (1) Preparation of resin sheet / glass fiber cloth: The resin sheet is Lotte Chemical polycarbonate SC-1220R, MI (300 °C, 1.2 kg) 18 - 30, with a thickness of 0.25 mm, a width of 1.2 m, and a continuous resin sheet.

[0030] The glass fiber cloth is Chongqing International fine yarn industrial cloth 3788, with a weave of 12-end satin, a thickness of 1.0 mm, a width of 1.2 m, and having fire prevention and protection properties.

[0031] (2) Double-steel belt continuous press composite prepreg: Place the resin sheet and the glass fiber cloth at the fixed positions of the double-Teflon belt press, with a processing temperature of 300 - 320 °C, a pressure of 2.5 - 3.5 Bar, and a designed glass fiber content of 65%. Start the double-steel belt continuous press to obtain the glass fiber cloth prepreg, with a prepreg thickness of 1.2 mm and a width of 1.2 m.

[0032] (3) Cross-cutting of fiber cloth prepreg: Use a cross-cutting machine to cut the prepreg into fixed-length prepreg sheets with a length of 1.2 m.

[0033] (4)Pre-shearing of fiber cloth prepreg: Unfold the 3D model of the battery cover into 2D to form pre-shearing data, and then input the data into the processing system of the cloth cutting machine to form the shape to be cut. Place the 1.2m * 1.2m prepreg sheet on the cloth cutting machine for pre-shearing of the sheet. The cloth cutting machine is a composite material cutting machine with tungsten carbide blades for one-key cutting of materials.

[0034] (5)Local reinforcement: According to the design requirements, use fiber reinforcement sheets of a certain size to locally reinforce the flange position and interface position of the battery cover, and prepare a certain number and size of reinforcement sheets. The fiber reinforcement sheet is a short glass fiber reinforced polycarbonate sheet formed by injection molding process, with a fiber content of 40%, a thickness of 1.2mm, and a width of 25mm. The flange layout of the reinforcement sheet has one horizontal and one vertical strip, a total of 4 strips, with a horizontal length of 1200mm and a vertical length of 1175mm. The interface layout of the reinforcement sheet has one strip for each of the 4 interfaces, with a length of 40mm.

[0035] (6)Laying: Place the pre-cut sheet on the tooling on one side of the tunnel furnace, and then place the reinforcement sheet at the target position of the pre-cut sheet to complete the laying.

[0036] (7)Oven heating: Start the conveyor belt of the tunnel furnace, input the laid sheet into the furnace for heating. The tunnel furnace uses infrared heating, heats at 300°C for 15 seconds, and after heating, send it to the mold on the press.

[0037] (8)Compression molding: Open the laying tooling, place the heated sheet on the mold, and the laying tooling returns to its original position. At this time, the press closes the mold, requiring a mold closing time of 10 seconds. During the compression molding process of the sheet, the pressure holding time is 60 seconds and the pressure is 1000 tons.

[0038] (9)Post-processing and inspection: Open the mold of the press, use a manipulator or manually take out the battery cover product for post-treatment and inspection to complete the entire process of pressing the battery cover product.

[0039] The following are the performance of the battery cover: Continuous fiber reinforcement, high strength (>360MPa), high modulus (>23GPa); Compression molding in one piece, modular integration: simple process, high efficiency (90 - 120s); High-performance sheet structure reinforcement: 20 - 30% lighter than thermosetting materials, and the shell thickness can be reduced to less than 1.2mm.

[0040] Burn the solid plate with a butane torch, and the measured temperature is 1000 - 1100°C. After the traditional thermosetting material burns for 10 minutes, the flame begins to pass through the plate.

[0041] The bio-based polyamide composite board does not burn through after being flame burned for 1 hour, passes the UL 94 V-0 certification, has very high flame retardancy performance, and the client passes the thermal runaway test of the battery cell.

[0042] 。

[0043] The above only discloses several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A thermoplastic new energy vehicle battery cover molding method, characterized in that: The following steps are involved: a. Fix a layer of resin sheet, a layer of fiber cloth and a layer of resin sheet on a double-belt press as required, start the double-belt press, and process into a fiber cloth prepreg with a fiber content of 65-70%; b. Cutting the fiber cloth prepreg obtained in step a into sheets of target size by a crosscutting machine and a longitudinal cutting machine; c. Expand the three-dimensional model of the battery cover in two dimensions to form pre-cutting data, and then input the data into the processing system of the cloth cutting machine to form the shape to be cut, and place the sheet obtained in step b on the cloth cutting machine to pre-cut the sheet; d. According to the design requirements, use fiber reinforcement sheets of a certain size to locally reinforce the locations that need to be reinforced, and prepare reinforcement sheets of a certain number and size; e. Place the pre-sheared sheet obtained in step c on the tooling on one side of the tunnel furnace, and then place the reinforcing sheet on the target position of the pre-sheared sheet to complete the paving; f. Start the tunnel furnace conveyor belt, input the paved sheet into the furnace for heating for 10-30 seconds, and then send it to the mold on the press after heating; g. The material laying tooling is opened, the heated sheet is laid on the mold, and the material laying tooling is returned to its original position. At this time, the press is closed to carry out the molding process of the sheet, and the holding time is 45-75 seconds; h. The press opens the mold, takes out the battery cover product, and performs post-processing and testing to complete the entire process of pressing the battery cover product.

2. A thermoplastic new energy vehicle battery cover molding method according to claim 1, characterized in that: The resin sheet in step a is PA engineering plastic, PC engineering plastic, PP general plastic, PPS engineering plastic or PEEK engineering plastic.

3. A thermoplastic new energy vehicle battery cover molding method according to claim 1, characterized in that: The fiber cloth in step a is glass fiber, carbon fiber, or a combination of both.

4. A thermoplastic new energy vehicle battery cover molding method according to claim 1, characterized in that: The fiber cloth in step a is an alkali-free glass fiber cloth or a carbon fiber cloth treated with a coupling agent.

5. A thermoplastic new energy vehicle battery cover molding method according to claim 1, characterized in that: The double belt press in step a is a Teflon double belt continuous press or a double steel belt continuous press.

6. A thermoplastic new energy vehicle battery cover molding method according to claim 1, characterized in that: The cloth cutting machine in step c is a composite material cutting machine with a tungsten steel blade, and the material can be cut with one click.

7. A thermoplastic new energy vehicle battery cover molding method according to claim 1, characterized in that: The glass fiber reinforced sheet in step d is formed by injection molding or compression molding, and the glass fiber content is 30-50%. The matrix of the reinforced sheet is the same as the matrix material of the main body.

8. A thermoplastic new energy vehicle battery cover molding method according to claim 1, characterized in that: The tunnel furnace in step e / f uses carbon fiber heating tubes, ceramic heating tubes or infrared heating, and adopts a single-layer or double-layer design.

9. A thermoplastic new energy vehicle battery cover molding method according to claim 1, characterized in that: The time from the completion of the heating of the sheet to the closing of the press mold needs to be controlled within 15 seconds to avoid the sheet losing temperature during the time and affecting the pressing of the product.

10. A thermoplastic new energy vehicle battery cover molding method according to claim 1, characterized in that: The mold in step g is a cold mold, and the mold temperature is controlled by a mold temperature controller to maintain at 40-120 degrees.

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