A method for integrally forming a battery box cover plate with a super-hybrid surface core sandwich structure

Abstract

The application provides a kind of super hybrid face core sandwich structure battery box cover plate integrated forming method, the top layer fiber thermoplastic resin composite material, steel plate and bottom layer fiber thermoplastic resin composite material are preheated, then honeycomb core material is placed between composite material and steel plate, and non-solidified super hybrid laminated sheet is obtained;The super hybrid laminated sheet is heated and pressurized and kept warm, and the hot pressing forming of the super hybrid laminated sheet is realized;Finally, the battery box cover plate in the hot pressing mold is sent to the cold pressing mold and pressurized and kept warm on the circulating guide rail by using the metal pad with rubber film, and the curing and shaping of the super hybrid laminated sheet battery box cover plate are realized.The process described in the application can realize effective combination of steel plate and honeycomb core material, steel plate and fiber thermoplastic resin composite material in the complex deformation process, and prepare super hybrid face core sandwich structure battery box cover plate.The forming process is simple, the hot-cold mold is coupled, the equipment production efficiency is high, and it is easy to industrialization.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation, and particularly relates to an integrated molding method for a battery box cover plate with a super hybrid face-core sandwich structure. Background Technology

[0002] Lightweighting is a perennial theme in the automotive industry. Battery systems are a key component of new energy vehicles, making lightweighting a crucial direction for their development. Steel, with its high strength, good impact resistance, good machinability, and low cost, is a candidate material for battery boxes. However, high-strength steel has a high density and weight, severely limiting its application in lightweight battery box design. Composite materials, with their high specific strength, good designability, and good corrosion resistance, have become the preferred material in lightweight battery box design. Due to the variable operating environment of automobiles and the harsh service conditions of battery boxes, battery box cover components generally require excellent impact resistance, corrosion resistance, heat insulation, and fire resistance. Relatively mature fiber-metal laminates cannot adequately meet the performance requirements of battery box covers. Therefore, it is necessary to further introduce honeycomb materials with high specific stiffness and excellent impact energy absorption performance into the fiber-metal laminate to design a new generation of composite battery box covers. However, multilayered hyperhybrid composite materials present complex interfacial bonding challenges. The introduction of honeycomb materials further complicates the bonding of hyperhybrid face-core structure composite plates. Achieving rapid, integrated bonding across multiple interfaces is crucial for the fabrication of hyperhybrid battery box covers and is also a major factor limiting their efficient production. This invention provides an integrated molding apparatus and method for hyperhybrid face-core sandwich structure battery box covers, effectively solving the aforementioned problems and enabling efficient and stable industrial-scale production of the covers. Summary of the Invention

[0003] This invention provides an integrated molding method for a battery box cover component with a super hybrid face-core sandwich structure, comprising the following steps:

[0004] Step S1: The robot arm places the bottom fiber-reinforced resin composite material and the surface-treated steel plate on a hot concave mold with a metal pad for preheating, and places the top fiber-reinforced resin composite material on a hot convex mold for preheating.

[0005] Step S2: Place the honeycomb core material between the preheated top fiber-reinforced composite material and the steel plate in step S1 and position it. Use a hot molding press to quickly perform a one-time progressive molding to form a battery box cover with an ultra-hybrid face core sandwich structure.

[0006] Step S3: The super hybrid core sandwich structure battery box cover plate after hot pressing in step S2 is moved to a cold pressing mold of the same size using a slide rail and a metal pad for pressure holding, cooling and shaping.

[0007] The integrated molding method described above uses a molding device composed of a hot-cold combination mold. The component is hot-pressed in the hot mold and shaped in the cold mold. The component is rapidly and stably transferred between the hot and cold molds by a slide rail and a metal pad.

[0008] The integrated molding method described above results in a super-hybrid sandwich structure battery box cover plate composed of a bottom fiber resin composite board, a steel plate, a honeycomb core material, and a top fiber resin composite board. It has multiple interface combinations and is a super-hybrid component with high molding difficulty.

[0009] In the integrated molding method described above, the preheating temperature of the fiber-reinforced composite material and the steel plate on the hot mold is 160-180°C, and the preheating time is 1-3 minutes. The temperature of the unpreheated honeycomb core material is at room temperature.

[0010] The integrated molding method described above uses high-strength steel or aluminum alloy as the steel plate in the battery box cover of the ultra-hybrid sandwich structure, with a thickness of 0.6 to 1.2 mm.

[0011] The integrated molding method described above uses a honeycomb core material comprising thermoplastic resin honeycomb or aramid paper honeycomb with a thickness of 3–6 mm.

[0012] The integrated molding method described herein uses resins such as polypropylene, polyethylene, and polycarbonate in the fiber-reinforced composite material, and fibers such as carbon fiber, glass fiber, and ceramic fiber.

[0013] The integrated molding method requires sandblasting or silanizing the surface of the steel plate before molding to form a rough structure with a thickness of 400-600μm to facilitate resin bonding. After the treatment, a double-layer adhesive film needs to be covered on the surface to facilitate the interface bonding of the honeycomb core material, steel plate and fiber composite material during the molding process.

[0014] The integrated molding method described above has multiple micro rollers on the edges of the hot punch and hot die, which can effectively prevent resin from overflowing from the mold during the molding process, ensuring the integrated molding quality of the battery box cover with the ultra-hybrid core sandwich structure.

[0015] The integrated molding method described above involves placing the room-temperature honeycomb core material between the preheated fiber-reinforced composite material and the steel plate for positioning, and then immediately molding it to ensure that the honeycomb core material is not fully preheated in the mold during molding to maintain high rigidity; otherwise, the honeycomb will collapse during the molding process.

[0016] The integrated molding method described above uses a stepped, progressive hot molding pressure, ranging from 3 to 8 MPa, while maintaining the molding temperature at 200 to 330°C for 4 to 8 minutes.

[0017] The integrated molding method described above involves placing a metal pad in the hot die. The shape and size of the metal pad are consistent with the die cavity, and the upper surface of the metal pad that contacts the workpiece is covered with a rubber film with a thickness of 0.5-2mm. The metal layer thickness is 1.5-2mm, which can improve the surface forming quality of the composite plate.

[0018] The integrated molding method described above achieves the transfer of components between hot and cold molds by moving metal pads on a slide rail. This slide rail is a circulating type, and multiple metal pads move rapidly between the hot and cold molds via the circulating slide rail, which can realize the continuous and efficient molding of the battery box cover plate with a super hybrid face-core sandwich structure.

[0019] The integrated molding method described above involves a cold molding pressure in the range of 4–6 MPa, a molding temperature of 10–30°C, and a holding time of 20–60 seconds.

[0020] In the described integrated molding method, the steel plate size is slightly smaller than the honeycomb size and the fiber-reinforced resin composite material size.

[0021] This invention provides an integrated molding method for a battery box cover component with a super-hybrid sandwich structure. The method involves preheating the top layer fiber-reinforced resin composite material, a steel plate, and the bottom layer fiber-reinforced resin composite material. Then, a honeycomb core material is placed between the preheated top layer fiber-reinforced composite material and the steel plate. A hot molding press is used for a single molding process to obtain a non-cured super-hybrid layer. The super-hybrid sandwich structure battery box cover, along with a metal pad, is then transferred to a cold-press mold of the same size for pressure holding and cooling to solidify its shape. Using the process described in this invention, bonding between the steel plate and the honeycomb core material, and between the steel plate and the fiber-reinforced resin composite material, can be achieved to prepare the super-hybrid sandwich structure battery box cover component. Under stepped progressive pressurization, the shear strength between the super-hybrid layers is higher. The molding process is simple and easily industrialized. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the fabrication process of the battery box cover component with a super-hybrid sandwich structure according to the present invention. 1-Robot arm, 2-Top layer fiber-reinforced resin composite material, 3-Hot punch, 4-Modible crossbeam, 5-Guide post, 6-Steel plate, 7-Bottom layer fiber-reinforced resin composite material, 8-Metal pad, 9-Hot die, 10-Honeycomb core material, 11-Robot arm, 12-Hot pressing component, 13-Cold die, 14-Cold punch, 15-Cold pressing component, 16-Metal pad, 17-Ejection mechanism.

[0023] Figure 2 This is a side view of the ultrahybrid faceted core sandwich structure of the present invention.

[0024] Figure 3 This is a schematic diagram showing the position of the tiny rollers.

[0025] Figure 4For the hot molding process of the battery box cover component of the ultra-hybrid sandwich structure of the present invention, a step-by-step progressive curve of molding pressure is preferred. Detailed Implementation

[0026] It should be noted that the following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the invention. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] Example 1

[0028] The steel plate is sandblasted to create a rough surface with a depth of approximately 400 μm. A release agent is sprayed onto the mold, and a metal pad (with the same shape and dimensions as the mold cavity) is placed inside the die cavity. A 0.5 mm thick rubber film is then applied to the upper surface of the metal pad in contact with the workpiece. The robotic arm sequentially places the bottom layer of glass fiber composite material (0.2 mm thick, 1300 mm × 1300 mm) and the high-strength Q345 steel plate (0.6 mm thick, 1200 mm × 1200 mm) above the hot die cavity for preheating. The robotic arm then clamps the top layer of glass fiber composite material (0.2 mm thick, 1300 mm × 1300 mm). A 0.2mm thick polypropylene honeycomb core (1200mm x 1200mm, with a circular cross-section diameter of 5mm) is placed under a hot die and preheated at 160℃ for 3 minutes. After preheating, a 3mm thick polypropylene honeycomb core (1200mm x 1200mm, with a circular cross-section diameter of 5mm) is placed on a steel plate. A robotic arm holds the top layer of glass fiber composite material and places it on the honeycomb core. The layers are arranged from bottom to top: glass fiber composite material, steel plate, honeycomb core material, and glass fiber composite material. An adhesive film is placed between each layer. The glass fiber composite material is resin-impregnated glass fiber, specifically EWR200-100 orthogonally woven fabric, and the resin material is polypropylene. The mold is closed for 6 seconds, the hot mold temperature is raised to 200℃, the hot mold pressure is increased from 3MPa to 6MPa, and the holding time is 4 minutes, resulting in a non-cured ultra-hybrid laminate with a thickness of 4mm and dimensions of 1300mm x 1300mm. After the holding time is completed, the mold is opened, and the metal pad carrying the ultra-hybrid cover plate is moved to the cold pressing mold via a circulating slide rail. The mold closing time is 6 seconds, the cold pressing mold temperature is 10℃, the molding pressure is 4MPa, and the holding time is 20 seconds. After completion, the formed part is removed, and the edges are trimmed to obtain a glass fiber ultra-hybrid laminate cover plate component.

[0029] Example 2

[0030] The aluminum alloy plate was subjected to silanization treatment to form a surface morphology of about 600 μm. A release agent is sprayed onto the mold. A metal pad is placed inside the cavity of the die (the shape and size of the metal pad are consistent with the die cavity). A 1mm thick rubber film is covered on the upper surface of the metal pad that contacts the workpiece. The robot first places the bottom carbon fiber composite material (thickness 0.3mm, size 1400mm×1400mm) and the high-strength Q345 steel plate (thickness 1.2mm, size 1300mm×1300mm) above the hot die for preheating. Then the robot holds the top carbon fiber composite material (thickness 0.3mm, size 1400mm×1400mm) and places it below the hot punch for preheating. The preheating temperature is 180℃ and the preheating time is 3min. After preheating, the polycarbonate honeycomb (thickness 6mm, size 1300mm×1300mm, circular cross-section diameter 7mm) is placed on the steel plate. The robot holds the top carbon fiber composite material and places it on the honeycomb. From bottom to top, the layers are carbon fiber composite material, steel plate, honeycomb core material, and carbon fiber composite material. An adhesive film is laid between each layer of material. The carbon fiber composite material is resin-impregnated carbon fiber, where the carbon fiber is T300 fiber tow and the resin material is polycarbonate. The molding process involves 8 seconds of mold closing, with the hot mold temperature raised to 330℃, the hot molding pressure increased from 3MPa to 8MPa, and the holding time 8 minutes, resulting in a non-cured ultra-hybrid laminate with a thickness of 7mm and dimensions of 1400mm × 1400mm. After the holding time, the mold is opened, and the ultra-hybrid component, supported by a metal pad, is moved to the cold pressing mold via a circulating slide rail. The mold closing time is 8 seconds, the cold mold temperature is 30℃, the molding pressure is 6MPa, and the holding time is 60 seconds. After the cold pressing, the mold is opened again, the formed part is removed, and the edges are trimmed to obtain a carbon fiber ultra-hybrid laminate cover plate-like component.

[0031] Example 3

[0032] The steel plate is sandblasted to achieve a surface morphology of approximately 500 μm. A release agent is sprayed onto the mold, and a metal pad (with the same shape and size as the mold cavity) is placed inside the die cavity. A 1.5 mm thick rubber film is then applied to the upper surface of the metal pad in contact with the workpiece. The robotic arm sequentially places the bottom layer of ceramic fiber composite material (0.4 mm thick, 1500 mm × 1500 mm) and the high-strength Q235 steel plate (1.0 mm thick, 1400 mm × 1400 mm) above the hot die cavity for preheating. The robotic arm then clamps the top layer of ceramic fiber composite material (thickness...)... A 0.4mm thick, 1500mm×1500mm core material was placed under a hot die and preheated at 175℃ for 2 minutes. After preheating, an aramid paper honeycomb (5mm thick, 1400mm×1400mm, hexagonal cross-section with 6mm side length) was placed on a steel plate. A robotic arm held the top layer of ceramic fiber composite material and placed it on the honeycomb. The layers were arranged from bottom to top: ceramic fiber composite material, steel plate, honeycomb core material, and ceramic fiber composite material, with an adhesive film between each layer. The ceramic fiber composite material consisted of resin-impregnated ceramic fibers, specifically CZ-100 orthogonally woven fabric, and polyethylene resin. The mold was closed for 10 seconds, the hot mold temperature was raised to 185℃, the hot mold pressure was increased from 3MPa to 5MPa, and the holding time was 5 minutes, resulting in a non-cured ultra-hybrid laminate with a thickness of 7mm and dimensions of 1500mm×1500mm. After the heat preservation period, the mold is opened, and the metal pad supporting the ultra-hybrid cover plate is moved to the cold pressing mold via a circulating slide rail. The mold closing time is 10 seconds, the cold mold temperature is 20℃, the molding pressure is 5.5MPa, and the heat preservation time is 40 seconds. After the heat preservation period, the mold is opened and the formed part is removed. The edges are trimmed to obtain a ceramic fiber ultra-hybrid laminate cover plate component.

[0033] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for integrally molding a battery box cover with a super-hybrid sandwich structure, characterized in that: The forming method includes the following steps: S1. The steel plate surface is sandblasted or silanized to form a rough structure with a thickness of 400-600μm to facilitate resin bonding. After treatment, a double-layer adhesive film is applied to the surface. To facilitate rapid feeding and movement of the composite plate, a metal pad is placed in the hot die. The upper surface of the metal pad that contacts the workpiece is covered with a 0.5-2mm rubber film. The shape and size of the metal pad are consistent with the die cavity. S2. The robotic arm places the bottom fiber-reinforced resin composite material and the surface-treated steel plate on a hot concave mold with a metal pad for preheating, and places the top fiber-reinforced composite material on a hot convex mold for preheating; S3. Place the honeycomb core material between the preheated top fiber-reinforced composite material and the steel plate in step S2 and position it. When the honeycomb core material is not fully preheated in the mold to maintain high rigidity, use a hot molding press to perform one molding. Multiple small rollers are set on the edges of the punch and die to prevent the resin from overflowing from the mold during the molding process, forming an ultra-hybrid face core sandwich structure irregular composite board. S4. The super hybrid face core sandwich structure irregular composite plate after hot pressing in step S3 is moved to a cold pressing mold of the same size along with metal pads using a slide rail for pressure holding, cooling and shaping; multiple metal pads move between the hot and cold molds, repeating step S2 to achieve continuous and efficient forming of the super hybrid face core sandwich structure composite plate.

2. The method for integral molding of a battery box cover plate with a super hybrid face-core sandwich structure according to claim 1, characterized in that: The invention relates to an integral molding device including a hot-cold combined molding system, a circulating slide rail, a robot, and a metal pad. The metal pad can carry the composite plate and move between the hot mold and the cold mold through the circulating slide rail.

3. The method for integral molding of a battery box cover plate with a super hybrid face-core sandwich structure according to claim 1, characterized in that: The ultra-hybrid sandwich structure composite panel is composed of a bottom fiber resin composite panel, a steel plate, a honeycomb core material, and a top fiber resin composite panel.

4. The method for integral molding of a battery box cover plate with a super hybrid face-core sandwich structure according to claim 1, characterized in that... In step S1, after sandblasting or silanization, a rough structure with a thickness of 400-600 μm is formed on its surface to facilitate the interfacial bonding of the honeycomb core material, steel plate, and fiber composite material during the molding process; the shape and size of the metal pad are consistent with the mold cavity, and the thickness of the rubber film is 0.5-2 mm. In step S2, the preheating temperature of the fiber reinforced composite material and the steel plate on the hot mold is 160-180℃, and the preheating time is 1-3 min.

5. The method for integrally molding a battery box cover plate with a super hybrid face-core sandwich structure according to claim 4, characterized in that: The fiber-reinforced composite material used has resins including polypropylene, polyethylene and polycarbonate, and fibers including carbon fiber, glass fiber and ceramic fiber. The steel plates used are high-strength steel or aluminum alloy, with a thickness of 0.6~1.2mm; the honeycomb core materials used include thermoplastic resin honeycomb or aramid paper honeycomb, with a thickness of 3~6mm.

6. The method for integrally molding a battery box cover plate with a super hybrid face-core sandwich structure according to claim 1, characterized in that: In S3, during the hot molding process, the hot molding pressure is gradually increased in a stepwise manner, within the range of 3~8MPa, while the molding temperature is maintained at 200~330℃ for 4~8min.

7. The method for integral molding of a battery box cover with a super-hybrid sandwich structure according to claim 1, characterized in that: In step S4, the cold molding pressure is in the range of 4~6MPa, the molding temperature is 10~30℃, and the holding time is 20~60s.

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