An integrated heating protection plate and its molding method

Abstract

This invention discloses an integrated heating and protective plate, comprising, from bottom to top, a third composite material layer, a PP honeycomb panel layer, a steel plate layer, a second composite material layer, a heating film layer, and a first composite material layer. The PP honeycomb panel layer has a recessed area for fitting and mounting the steel plate layer. The third composite material layer and the PP honeycomb panel layer are conformally shaped. The invention also includes a molding method for preparing the integrated heating and protective plate. This invention uses composite materials to obtain a bottom protective plate for a new energy battery pack that integrates heating, insulation, and protection functions. The structure is lightweight, reducing the weight of the battery pack protective plate while ensuring the airtightness of the battery pack, minimizing the appearance of air holes and gaps, reducing hole tolerances, and lowering the difficulty of subsequent assembly.

Description

Technical Field

[0001] This invention relates to the field of protective panel manufacturing technology, specifically to an integrated heating protective panel and its molding method. Background Technology

[0002] In the cold winter, the battery activity of new energy vehicles is low. Warming up the car allows the power battery to reach a more ideal working state; otherwise, it will have a certain impact on the driving range. Furthermore, the battery needs to be preheated before charging, and charging will only begin after the battery temperature reaches a certain level.

[0003] To ensure that new energy vehicle batteries reach suitable temperatures during vehicle start-up and charging in winter, battery pack designs incorporate insulation, protective, and heating layers. Current solutions to temperature issues involve assembling functional layers in the order of heating-insulation-protection, with the heating layer closest to the battery cells and connected to the bottom of the battery tray. However, existing battery pack protective plates may present the following problems:

[0004] (1) To ensure the airtightness of the battery pack, the lower tray of the battery pack and the heating layer are assembled using glue, sealing strips and mounting bolts. However, the sealing strips may age, and the glue seal may also develop pores or loosen and create gaps under vibration conditions.

[0005] (2) Currently, the combined thickness of the heating layer, insulation layer and protective layer can reach 15-30mm, which is quite thick. At the same time, since the protective layer is mostly made of metal materials with high density, for a battery pack of size 1000*1500mm, the weight of its heating layer, insulation layer and protective layer can reach 30kg, which is relatively heavy.

[0006] (3) Because the heating layer, insulation layer and protective layer may be produced and supplied by different suppliers, it is difficult to unify whether the hole position tolerance follows the upper or lower limit. There are many difficulties in assembly. The installation of bolts and the process of applying glue are very strict in terms of operation requirements. The operation is relatively complicated and the efficiency is low.

[0007] Therefore, how to solve the problems that arise when functional components such as insulation layers, protective layers, and heating layers are designed and assembled separately, such as their large thickness and weight, the difficulty in assembly due to misalignment of mounting holes, or poor interlayer sealing and conductivity, has become an urgent problem to be solved. Summary of the Invention

[0008] The purpose of this invention is to provide an integrated heating and protective plate and its molding method to solve the technical problems of poor airtightness and difficulty in assembly between the heating layer, insulation layer and protective layer in the prior art.

[0009] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution:

[0010] This invention provides an integrated heating and protection plate, which, from bottom to top, comprises a third composite material layer, a PP honeycomb panel layer, a steel plate layer, a second composite material layer, a heating film layer, and a first composite material layer. The PP honeycomb panel layer is provided with a recessed area that can be fitted and installed with the steel plate layer. The third composite material layer and the PP honeycomb panel layer are configured to conform to each other.

[0011] The third composite material layer, the second composite material layer, and the first composite material layer are all thermosetting resin-based reinforced fiber composite materials;

[0012] The second composite material layer and the first composite material layer are thermosetting bonded together and used to wrap and fix the heating film layer; the second composite material layer and the PP honeycomb panel layer are thermosetting bonded together and used to wrap and fix the steel plate layer.

[0013] In a preferred embodiment of the present invention, the steel plate layer is divided into a first steel plate and a second steel plate, the first steel plate and the second steel plate being located on the left and right sides of the sinking area respectively, and an intermediate assembly hole is provided between the first steel plate and the second steel plate, the intermediate assembly hole sequentially penetrating the first composite material layer, the second composite material layer, the PP honeycomb panel layer and the third composite material layer.

[0014] The present invention also provides a method for molding an integrated heating protection plate, comprising the following steps:

[0015] The third composite material plate, PP honeycomb plate, steel plate, second composite material plate, heating film, and first composite material plate are laid sequentially from bottom to top on the pre-pressing base plate to obtain the precast component;

[0016] The preform is rolled using rollers, and after rolling, the edge of the preform is clamped and moved into the mold.

[0017] After rolling, the first composite material layer, the second composite material layer, and the PP honeycomb panel layer are bonded together, and the steel plate layer and the heating film layer are positioned.

[0018] The preform is hot-pressed using a press, and the PP honeycomb panel and the third composite material panel melt and fill the pre-reserved mold cavity as the temperature rises.

[0019] After the product is molded, it is removed from the mold and placed to cool down. After the temperature drops, it is transferred to the laser cutting process to make holes in the product in order to obtain the integrated heating and protection plate.

[0020] As a preferred embodiment of the present invention, the planar rolling process includes the following steps:

[0021] The rollers are heated to a preheating temperature and rolled from the middle to both ends of the preform. The rollers conduct heat from the first composite material layer to the third composite material layer and expel air from the preform.

[0022] In a preferred embodiment of the present invention, the planar rolling process further includes the following steps:

[0023] The two rollers of the roller move relative to each other in the horizontal direction and rotate synchronously in opposite directions. After running to the end of the preform, they rotate back and stick together to perform a cycle of hot pressing.

[0024] As a preferred embodiment of the present invention, the surface temperature of the roller is 60-100℃.

[0025] As a preferred embodiment of the present invention, in the hot pressing molding step, the mold temperature is 130℃~170℃;

[0026] The formula for selecting mold pressure is T = S * F1 * F2 / F_table.

[0027] As a preferred embodiment of the present invention, the third composite material layer is composed of two 400g / ㎡ sheets, and the thickness after molding is 0.3-0.6mm.

[0028] As a preferred embodiment of the present invention, the second composite material layer is composed of 1-2 layers of 400g / ㎡ sheet material, and the thickness after molding is 0.3-0.6mm.

[0029] As a preferred embodiment of the present invention, the first composite material layer is composed of two 200g / ㎡ sheets, and the thickness after molding is 0.25-0.3mm.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] This invention uses composite materials to obtain a bottom protective plate for a new energy battery pack that integrates heating, heat preservation, and protection functions. The structure is lightweight and thin, resulting in a lighter weight after the battery pack is in use, thus achieving weight reduction of the battery pack protective plate. This invention is made of multi-layer composite materials by hot pressing, and each layer of material can be fully bonded and in contact, ensuring the airtightness of the battery pack and preventing the formation of air holes and gaps.

[0032] This invention provides a molding method for an integrated heating and protective plate. The assembly method is simple. When drilling, the materials that the machine passes through have similar hardness, so the drilling operation can be performed directly, reducing hole position tolerance and reducing the difficulty of subsequent assembly. At the same time, the use of preheating roller pressing not only provides pressure to the material, but also provides a certain amount of heat, so that the steel plate and heating film can be initially connected with the composite material, reducing the probability of surface misalignment during subsequent drilling. Attached Figure Description

[0033] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0034] Figure 1 An exploded view of the integrated heating protection plate structure is provided for this invention;

[0035] Figure 2 Provided for the present invention Figure 1 A perspective view of the integrated heating protection plate in the embodiment shown;

[0036] Figure 3 Provided for the present invention Figure 1 Top view of the integrated heating protection plate in the illustrated embodiment.

[0037] Figure 4 This is a schematic flowchart illustrating the molding method of the integrated heating protection plate provided by the present invention.

[0038] The labels in the diagram represent the following:

[0039] 1-Third composite material layer; 2-PP honeycomb panel layer; 3-Steel plate layer; 4-Second composite material layer; 5-Heating film layer; 6-Heating film layer; 7-Four-sided assembly holes; 8-Sunken area; 9-Center assembly hole;

[0040] 301 - First steel plate; 302 - Second steel plate. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] See Figures 1 to 3The present invention provides an integrated heating protection plate, characterized in that it comprises, from bottom to top, a third composite material layer 1, a PP honeycomb plate layer 2, a steel plate layer 3, a second composite material layer 4, a heating film layer 5, and a first composite material layer 6.

[0043] In a preferred embodiment of the present invention, the third composite material layer 1, the second composite material layer 4, and the first composite material layer 6 are all composite material plates. The composite material plates are composed of thermosetting resin-based reinforced fiber composite material plates. The thickness of each layer is recommended to be controlled between 0.6-0.9 mm. The function changes depending on the position of the thermosetting resin-based reinforced fiber composite material plate.

[0044] In a preferred embodiment of the present invention, the third composite material layer 1 is used to fix the position of the PP honeycomb panel layer 2, prevent the PP honeycomb panel layer 2 from moving during the movement, and at the same time protect the PP honeycomb panel layer 2, thus playing a protective role for the PP honeycomb panel layer 2.

[0045] In a preferred embodiment of the present invention, the second composite material layer 4 is used to fix the steel plate layer 3 and the heating film layer 5. During the hot pressing process, one side of the second composite material layer 4 contacts and adheres to the PP honeycomb panel layer 2, so that the steel plate is sandwiched between the second composite material layer 4 and the PP honeycomb panel layer 2, thereby positioning the steel plate. At the same time, the second composite material layer 4 has adhesive properties, which can pre-position the steel plate before mold forming, preventing the steel plate from shifting before hot pressing. The other side of the second composite material layer 4 contacts and adheres to the first composite material layer 6, thereby positioning the heating film layer 5. At the same time, both the second composite material layer 4 and the first composite material layer 6 have adhesive properties, which can pre-position the heating film layer 5 before mold forming, preventing the heating film layer 5 from shifting before hot pressing.

[0046] In a preferred embodiment of the present invention, the first composite material layer 6 is used to fix the heating film layer 5, and at the same time can protect the heating film layer 5 and position the heating film during stacking. Since the first composite material layer 6 has a certain degree of adhesion, it can prevent its displacement before hot pressing.

[0047] In particular, in this embodiment, the heating layer is a PI electric heating film formed by heat sealing with a polyimide film as the outer insulator and metal foil and metal wire as the inner conductive heating element under high temperature and high pressure.

[0048] Before hot pressing, the main structure of the heating layer is twisted into an S-shape. After twisting, the filamentous structure forms a fixed structure, which plays a heating role between the second composite material layer 4 and the first composite material layer 6. The interfaces of the anode and cathode are located at the edge of the entire protective plate and can be respectively set between two adjacent four-sided mounting holes 7.

[0049] In this invention, the advantage of the heating wire is that it can not only quickly provide a thermal environment to the battery, but also, due to the gaps between the heating wires, the first composite material layer 6 and the second composite material layer 4 can be directly bonded together during the layup process. Both the first composite material layer 6 and the second composite material layer 4 have a certain degree of adhesion, which facilitates the positioning of the entire heating film, prevents it from shifting before hot pressing, prevents the interface between the anode and cathode from going astray, and improves the connection accuracy.

[0050] Meanwhile, after hot pressing, each position of the heating wire of the heating film layer 5 is sealed and bonded inside the first composite material layer 6 and the second composite material layer 4, which makes it less likely for air holes to appear during subsequent cutting and drilling, or for gaps to appear due to vibration. It also prevents the wire from falling off during subsequent use.

[0051] In this invention, the assembly accuracy of the heating film layer is provided by its specific shape, composition and material properties of the first composite material layer 6 and the second composite material layer 4. This not only simplifies the assembly difficulty of the heating layer, but also reduces the probability of the heating layer shifting after layup, and reduces phenomena such as pores and vibration gaps that occur when the material layer is punched after hot pressing and during use.

[0052] In a preferred embodiment of the present invention, the honeycomb panel material can be selected as PP. PP is a thermoplastic material with good adhesion to thermosetting resin-based materials, and it will not delaminate after molding. PP honeycomb panels have strong compressive and impact resistance; PP honeycomb panels absorb external forces, thereby reducing damage caused by impacts and collisions; they are lightweight and high-rigidity, environmentally friendly, shock-absorbing, cold-resistant, sound-insulating, heat-insulating, moisture-proof, and heat-insulating. Note that materials with a flame retardant rating of UL94 V0 should be selected. The PP honeycomb panel 2 can deform during hot pressing, and the PP honeycomb panel 2 mainly has a buffering function, providing cushioning protection for the steel plate, heating film, and the internal structure of the battery.

[0053] Notably, the PP honeycomb panel can also deform during the subsequent hot pressing process, providing fitting gaps for the steel plate layer 3 and reducing air holes and adhesive gaps between layers caused by the presence of non-convex surfaces such as the protective layer. After the material is formed, the PP honeycomb panel layer 2 is provided with a recessed area 8 that can fit and install the steel plate layer 3, and the third composite material layer 1 and the PP honeycomb panel layer 2 are set in a conformal manner.

[0054] In a preferred embodiment of the present invention, the steel plate layer 3 can be made of high-strength steel with a thickness of 0.7-1.0 mm. The steel plate layer 3 provides rigid protection for the heating film and the internal structure of the battery, preventing the heating film and the internal structure of the battery from being subjected to severe impact. The second composite material layer 4 and the PP honeycomb panel layer 2 are thermosetting and bonded together to wrap and fix the steel plate layer 3, preventing air holes and gaps between the steel plate layer 3 and other surface layers, improving the overall strength of the material, reducing the probability of surface layer misalignment during subsequent drilling, and further improving the shock resistance of the protective plate because the steel plate layer 3 can be embedded in the PP honeycomb panel layer 2 after molding.

[0055] The area protected by the high-strength steel plate is determined according to needs. It can be placed across the entire surface, or its position and size can be determined based on weak points that may pose a puncture risk during vehicle operation. Common high-strength steel grades such as DP590, DP780, and DP980 can be selected, or stainless steel can be used; material requirements can be changed according to customer needs. Double-sided electrophoresis is required before the steel plate is laminated to ensure adhesion to the composite material layer.

[0056] In this invention, the first composite material layer 6 is provided with a plurality of peripheral mounting holes 7, which are arranged downward through the second composite material layer 4, the PP honeycomb panel layer 2 and the third composite material layer 1.

[0057] The mounting holes 7 are located on the edge of the integrated heating and protective plate and do not penetrate the heating film layer 5 and the steel plate layer 3, which can reduce damage to the insulation layer and the heating layer. Since the materials that the machine passes through during drilling have similar hardness, the drilling operation can be carried out directly, reducing the hole position tolerance and reducing the difficulty of subsequent assembly. At the same time, not penetrating the insulation layer and the heating layer during drilling can also protect the connection effect between the insulation layer, the heating layer and the protective layer.

[0058] The above describes the connection between the steel plate layer 3 and the composite material layer and the PP honeycomb panel layer, as well as the connection between the heating film layer 5 and the composite material layer. The present invention also improves the connection effect between the steel plate layer 3 and the heating film layer 5 by improving the steel plate layer 3.

[0059] Specifically, the steel plate layer 3 is divided into a first steel plate 301 and a second steel plate 302. The first steel plate 301 and the second steel plate 302 are located on the left and right sides of the sinking area 8, respectively. A connection section is provided between the first steel plate 301 and the second steel plate 302 for connecting the second composite material layer 4 and the PP honeycomb panel layer 2. At the same time, a middle assembly hole 9 is provided on the connection section, which can further improve the protection strength and reduce the stress on the connection section.

[0060] In particular, the heating layer also has gaps in the connection area for the intermediate assembly hole 9 to pass through.

[0061] Ordinary composite materials can bond steel plates and heating films, but this invention uses an S-shaped heating film and a partitioned steel plate, which can not only fix the steel plate and heating film in the protective plate at the same time, but also improve the fixing effect between the two and increase the strength of the materials.

[0062] The above materials can be laid in layers from bottom to top or from top to bottom, with the laying method being optional. Furthermore, due to the relatively complex structure of the steel plate and heating film, they are prone to movement during the transfer after the laying is completed. If movement occurs, it will not only affect the protective strength of the plate but also the drilling process. At the same time, the special structure of the steel plate and heating film makes it difficult to expel air bubbles during the hot pressing process.

[0063] To solve the above problems, see the accompanying drawings of this invention. Figure 4 As shown, the present invention also provides a molding method for preparing the above-mentioned integrated heating protection plate, comprising the following steps:

[0064] The third composite material plate, PP honeycomb plate, steel plate, second composite material plate, heating film, and first composite material plate are laid sequentially from bottom to top on the pre-pressing base plate to obtain the precast component;

[0065] The preform is rolled using rollers, and after rolling, the edge of the preform is clamped and moved into the mold.

[0066] After rolling, the first composite material layer, the second composite material layer, and the PP honeycomb panel layer are bonded together, and the steel plate layer and the heating film layer are positioned.

[0067] The preforms are hot-pressed using a press, and the PP honeycomb panels and the third composite material panels melt and fill the pre-reserved mold cavity as the temperature rises.

[0068] After the product is molded, it is removed from the mold and placed to cool down. After the temperature drops, it is transferred to the laser cutting process to make holes in the product in order to produce an integrated heating and protection plate.

[0069] The present invention first performs planar hot pressing on the preform, that is, preheated roller pressing, which not only provides pressure to the material, but also provides a certain amount of heat, so that the steel plate and the heating film can be initially connected with the composite material, and the composite material can also be initially bonded together, preventing the steel plate and the heating film from shifting during the transfer to the mold.

[0070] Furthermore, to prevent the preform from moving during the rolling process, planar rolling includes the following steps:

[0071] The rollers are heated to the preheating temperature and rolled from the middle to both ends of the preform. The preform is fixed during the rolling process. The rollers conduct heat from the first composite material layer to the third composite material layer and expel air from the preform.

[0072] Specifically, two identical rollers can be used. The two roller shafts move relative to each other in the horizontal direction and rotate synchronously in opposite directions. After running to the end of the preform, they rotate back and stick together to perform a cycle of hot pressing.

[0073] The surface temperature of the rollers should not be too high, as this will cause deformation of the preform and make it difficult to hot press into the mold later. Therefore, the surface temperature of the rollers should be 60-100℃. The surface temperature of the rollers is mainly controlled by the ambient temperature, and in specific operations, it is affected by the factory temperature and the type of material.

[0074] During hot pressing, the mold temperature is 130℃~170℃, and the mold pressure is selected according to the product design thickness ratio and the mold projection area.

[0075] For specific mold pressure selection, please refer to the formula T = S * F1 * F2 / F.

[0076] During production, the mold structure is designed according to the different shapes of the products.

[0077] Specifically, the third composite material layer consists of two 400g / ㎡ sheets, with a thickness of 0.3-0.6mm after molding; the second composite material layer consists of one to two 400g / ㎡ sheets, with a thickness of 0.3-0.6mm after molding; and the first composite material layer consists of two 200g / ㎡ sheets, with a thickness of 0.25-0.3mm after molding.

[0078] The third composite layer differs from the other composite layers in its gram weight selection because, after the two 200g / m² sheets are cured, the surface resin can completely cover the PI film of the lower heating film layer, ensuring the surface quality of the finished product. The steel plate position can be determined using customized tooling for correction. The composite prepreg sheet itself has a certain viscosity, making it less prone to displacement after layup, thus ensuring the correct position of the steel plate after molding.

[0079] The following specific embodiments illustrate the molding method of the integrated heating protection plate.

[0080] Example 1:

[0081] 1. Select thermosetting resin-based reinforced fiber composite material as the composite material layer, and pre-treat the materials to be used, including cutting, electrophoresis, surface cleaning and other processes for each layer of material.

[0082] 2. The material is laid up in layers, with the following layering sequence from bottom to top: third thermosetting resin-based reinforced fiber composite material layer, PP honeycomb panel layer, steel plate layer, second thermosetting resin-based reinforced fiber composite material layer, heating film layer, and first thermosetting resin-based reinforced fiber composite material layer.

[0083] The thickness of the third thermosetting resin-based reinforced fiber composite material layer can be relatively thick. It is recommended to use two layers of 400g / ㎡ material sheets, with a thickness of 0.55mm after molding.

[0084] The second thermosetting resin-based reinforced fiber composite layer can be thinner, and it is recommended to use one layer of 400g / ㎡ sheet, with a thickness of 0.4mm after molding;

[0085] The thickness of the first thermosetting resin-based reinforced fiber composite layer can be relatively thin. It is recommended to use two layers of 200g / ㎡ sheet material, with a thickness of 0.25mm after molding.

[0086] 3. Place the precast component after the layup is completed into the mold and hot press it with a press. The PP honeycomb panel will melt and fill the pre-reserved mold cavity as the temperature rises, while other excess parts will melt and be extruded from the mold along with the excess resin of the composite material layer as the press pressure increases.

[0087] 4. After the product is molded, it is removed from the mold and placed to cool down. After the temperature drops, it is transferred to the laser cutting process to machine the designed holes on its surface.

[0088] 5. Assemble the bushing or foam layer according to the product design requirements. The product molding process is now complete.

[0089] The integrated heating and protection plate of this embodiment is lightweight and thin, resulting in a light weight after being used in the battery pack. The embodiment is made of multi-layer composite material by hot pressing, and each layer of material can be fully bonded and in contact, ensuring the airtightness of the battery pack and preventing the formation of air holes and gaps.

[0090] The molding method for producing the integrated heating and protective plate described in this embodiment is simple to assemble. The materials that the machine passes through during drilling have similar hardness, so drilling can be performed directly, reducing hole tolerance and simplifying the later assembly process. At the same time, the use of preheating rollers not only provides pressure to the material but also provides a certain amount of heat, enabling the steel plate and heating film to form a preliminary connection with the composite material, reducing the probability of surface misalignment during later drilling.

[0091] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A molding method for an integrated heating protection plate, in, The heating protection plate includes, from bottom to top, a third composite material layer (1), a PP honeycomb panel layer (2), a steel plate layer (3), a second composite material layer (4), a heating film layer (5), and a first composite material layer (6). The PP honeycomb panel layer (2) is provided with a recessed area (8) that can fit and install the steel plate layer (3). The third composite material layer (1) and the PP honeycomb panel layer (2) are arranged in a conformal manner. The third composite material layer (1), the second composite material layer (4), and the first composite material layer (6) are all thermosetting resin-based reinforced fiber composite materials; Wherein, the second composite material layer (4) and the first composite material layer (6) are thermosetting bonded together and wrap and fix the heating film layer (5), and the second composite material layer (4) and the PP honeycomb panel layer (2) are thermosetting bonded together and wrap and fix the steel plate layer (3); The steel plate layer (3) is divided into a first steel plate (301) and a second steel plate (302). The first steel plate (301) and the second steel plate (302) are located on the left and right sides of the sinking area (8), respectively. An intermediate assembly hole (9) is provided between the first steel plate (301) and the second steel plate (302). The intermediate assembly hole (9) passes through the first composite material layer (6), the second composite material layer (4), the PP honeycomb panel layer (2), and the third composite material layer (1) in sequence. The molding method is characterized by comprising the following steps: The third composite material plate, PP honeycomb plate, steel plate, second composite material plate, heating film, and first composite material plate are laid sequentially from bottom to top on the pre-pressing base plate to obtain the precast component; The preform is rolled using rollers, and after rolling, the edge of the preform is clamped and moved into the mold. After rolling, the first composite material layer, the second composite material layer, and the PP honeycomb panel layer are bonded together, and the steel plate layer and the heating film layer are positioned. The preform is hot-pressed using a press, and the PP honeycomb panel and the third composite material panel melt and fill the pre-reserved mold cavity as the temperature rises. After the product is molded, it is removed from the mold and placed to cool down. After the temperature drops, it is transferred to the laser cutting process to make holes in the product in order to obtain the integrated heating and protection plate. The rollers are heated to a preheating temperature and rolled from the middle to both ends of the preform. The rollers conduct heat from the first composite material layer to the third composite material layer and expel air from the preform.

2. The molding method according to claim 1, characterized in that, The planar roller pressing also includes the following steps: The two rollers of the roller move relative to each other in the horizontal direction and rotate synchronously in opposite directions. After running to the end of the preform, they rotate back and stick together to perform a cycle of hot pressing.

3. The molding method according to claim 1, characterized in that, The surface temperature of the roller is 60-100℃.

4. The molding method according to claim 1, characterized in that, The third composite material layer consists of two layers of 400g / ㎡ sheet material, with a thickness of 0.3-0.6mm after molding.

5. The molding method according to claim 1, characterized in that, The second composite material layer consists of 1-2 layers of 400g / ㎡ sheet material, with a thickness of 0.3-0.6mm after molding.

6. The molding method according to claim 1, characterized in that, The first composite material layer consists of two 200g / ㎡ sheets, with a thickness of 0.25-0.3mm after molding.

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