Prepreg molding method and prepreg molding device

Abstract

The invention relates to a prepreg forming method and a prepreg forming device.The prepreg forming method comprises the steps that multiple layers of prepregs are sequentially laid in a first containing part of a pre-compaction device, pre-compaction treatment is conducted on the prepregs located in the first containing part through the pre-compaction device, so that the flatness of the prepregs is changed, and then the prepregs are formed; an intermediate is obtained; taking out the intermediate from the first accommodating part, and placing the intermediate in a second accommodating part of the pressing mold; placing the press-fit mold attached with the intermediate in hot pressing equipment, performing hot pressing treatment of step-by-step pressurization on the press-fit mold through the hot pressing equipment, and performing first vacuumizing treatment on the intermediate positioned in the second accommodating part after each time of pressurization treatment so as to remove gas generated in the hot pressing treatment process of the intermediate; and the intermediate subjected to hot pressing treatment is subjected to demolding treatment to obtain the prepreg product, so that the flatness of the intermediate can be improved, and pores in the prepreg product can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material preparation, and in particular to a molding method of prepreg and a molding device of prepreg. BACKGROUND

[0002] With the increasing demand for lightweight and high-efficiency manufacturing in the fields of low-altitude economy and new energy vehicles, the medium-temperature prepreg has become an important intermediate for research and manufacturing due to its low curing temperature (80-150℃).

[0003] In the related art, the curing period of the medium-temperature prepreg is long, the energy consumption of the hot-pressing equipment is high, and the flowability of the prepreg in the molten state is poor, which is prone to cause defects such as lack of glue and pores between the prepreg layers and the surface, and has an adverse effect on the mechanical properties of the prepreg product. SUMMARY

[0004] To overcome the problems in the related art, the present application provides a molding method of prepreg and a molding device of prepreg.

[0005] According to a first aspect of the present application, a molding method of prepreg is provided, comprising: sequentially laying multiple layers of prepreg in a first accommodating portion of a pre-compaction device, and pre-compacting the prepreg in the first accommodating portion by the pre-compaction device to change the flatness of the prepreg, to obtain an intermediate body; taking the intermediate body out of the first accommodating portion and placing it in a second accommodating portion of a pressing die; placing the pressing die with the intermediate body in a hot-pressing equipment, and performing step-by-step pressurization of the pressing die by the hot-pressing equipment, and after each pressurization, performing first vacuumizing treatment on the intermediate body in the second accommodating portion to remove the gas generated during the hot-pressing treatment of the intermediate body; performing demolding treatment on the intermediate body after the hot-pressing treatment to obtain a prepreg product.

[0006] In some embodiments of the present application, the step of sequentially laying multiple layers of prepreg in a first accommodating portion of a pre-compaction device, and pre-compacting the prepreg in the first accommodating portion by the pre-compaction device to change the flatness of the prepreg, to obtain an intermediate body, comprises: placing a first layer of the prepreg in the first accommodating portion, and performing second vacuumizing treatment on the first layer of the prepreg in the first accommodating portion by the pre-compaction device; sequentially laying multiple groups of the prepreg on the first layer of the prepreg, and after laying each group of the prepreg, performing third vacuumizing treatment on the prepreg in the first accommodating portion by the pre-compaction device. Each of the pre-pregs includes at least one layer of the pre-preg.

[0007] In some embodiments of the present application, the hot pressing process of the step-by-step pressurization of the compression mold by the hot pressing equipment, and after each pressurization process, the first vacuumizing process of the intermediate body in the second accommodating part, comprises: The first hot pressing process of the compression mold by the hot pressing equipment using a first pressure; The first vacuumizing process of the intermediate body in the compression mold after the first hot pressing process; The second hot pressing process of the compression mold by the hot pressing equipment using a second pressure after the first vacuumizing process; The second vacuumizing process of the intermediate body in the compression mold after the second hot pressing process; The third hot pressing process of the compression mold by the hot pressing equipment using a third pressure after the second vacuumizing process; The third vacuumizing process of the intermediate body in the compression mold after the third hot pressing process; The third pressure is greater than the second pressure, and the second pressure is greater than the first pressure.

[0008] In some embodiments of the present application, the first pressure is less than or equal to 0.5 MPa; The second pressure is less than or equal to 1 MPa; The third pressure is less than or equal to 3 MPa.

[0009] In some embodiments of the present application, the hot pressing time of the hot pressing process after each pressurization is step-by-step increased.

[0010] In some embodiments of the present application, the hot pressing time of the third hot pressing process is greater than the hot pressing time of the second hot pressing process, and the hot pressing time of the second hot pressing process is greater than the hot pressing time of the first hot pressing process; The hot pressing time of the first hot pressing process is less than or equal to 5 min, the hot pressing time of the second hot pressing process is less than or equal to 10 min, and the hot pressing time of the third hot pressing process is less than or equal to 60 min.

[0011] In some embodiments of the present application, the hot pressing temperature of the hot pressing process after each pressurization is equal.

[0012] In some embodiments of the present application, before the compression mold with the intermediate body is placed in the hot pressing equipment, the forming method of the pre-preg further comprises: The hot-pressing equipment is preheated.

[0013] According to a second aspect of the present application, a forming device of a prepreg is provided, comprising: a pre-compaction device, the pre-compaction device comprising a first accommodating part for accommodating a prepreg and a pre-compaction part for pre-compacting the prepreg in the first accommodating part to change flatness of the prepreg to obtain an intermediate body; a pressing die, the pressing die comprising a first die and a second die matched with each other, the second die being provided with a second accommodating part for accommodating the intermediate body and a first vacuumizing device communicated with the second accommodating part; a hot-pressing equipment for performing step-by-step hot-pressing treatment on the pressing die with the intermediate body, after each step-by-step treatment, the vacuumizing device performing first vacuumizing treatment on the intermediate body in the second accommodating part to remove gas generated in the hot-pressing treatment.

[0014] In some embodiments of the present application, the first accommodating part is an accommodating bag, the accommodating bag comprising opposite first and second inner sides, the first inner side being used for carrying the prepreg, the first inner side being provided with a separation film layer, and the second inner side being provided with a breathable film layer. The pre-compaction part is a second vacuumizing device communicated with the accommodating bag.

[0015] The technical scheme provided by the embodiments of the present application can have the following beneficial effects: The molding method of the prepreg provided by the application changes the flatness of the multilayer prepreg through pre-compaction treatment by a pre-compaction device to obtain an intermediate body. The press mold with the intermediate body is placed in a hot-pressing device, and the press mold is subjected to step-by-step pressurization and hot-pressing treatment by the hot-pressing device. After each pressurization treatment, the intermediate body is subjected to first vacuumizing treatment to remove the gas generated in the intermediate body during the hot-pressing treatment. The intermediate body after the hot-pressing treatment is subjected to demolding treatment to obtain a prepreg product. The multilayer prepreg is subjected to pre-compaction treatment before hot-pressing treatment to change the flatness of the prepreg, so that the laid multilayer prepreg is more flat, and the prepreg is prevented from forming wrinkles, thereby preventing the multilayer prepreg from forming gaps due to wrinkles and protrusions, so that the intermediate body contains less air, which is beneficial to reducing the porosity of the subsequently formed prepreg product. The step-by-step pressurization and hot-pressing treatment of the press mold by the hot-pressing device is beneficial to quickly discharging the gas at the initial hot-pressing treatment, avoiding the problem that the gas cannot be discharged in time due to high pressure and is sealed in the interior of the intermediate body. Further step-by-step pressurization can improve the internal bonding of the intermediate body after most of the gas is discharged from the intermediate body, so that the prepreg in a molten state is more easily infiltrated into the gaps in the interior of the intermediate body, thereby expelling the bubbles out of the intermediate body and avoiding the air to be retained in the interior of the intermediate body to form pores, thereby reducing the porosity of the prepreg product after demolding and improving the mechanical properties of the prepreg product.

[0016] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the application. BRIEF DESCRIPTION OF DRAWINGS

[0017] The drawings incorporated into the specification and constituting a part of the specification show embodiments consistent with the application and, together with the specification, serve to explain the principles of the application.

[0018] Figure 1 is a step schematic diagram of a molding method of a prepreg according to an exemplary embodiment; Figure 2 is a step schematic diagram of a molding method of a prepreg according to an exemplary embodiment; Figure 3 is a schematic diagram of the internal structure of a press mold according to an exemplary embodiment; Figure 4 is a sectional view of a press mold according to an exemplary embodiment; Figure 5 is a schematic diagram of the internal structure of a pre-compaction device according to an exemplary embodiment.

[0019] In the figure: 1, pre-compaction device; 11, first accommodating part; 12, breathable film layer; 13, intermediate body; 14, isolation film layer; 2, compression mold; 21, first mold; 211, protruding part; 22, second mold; 221, recessed part; 23, second accommodating part; 24, air extraction valve; 25, gasket. DETAILED DESCRIPTION

[0020] The exemplary embodiments will be described in detail herein with reference to the accompanying drawings. In the following description, unless otherwise indicated, like numbers in the different drawings represent the same or similar elements. The following exemplary embodiments described in the detailed description are not meant to be an all-inclusive description of all aspects of the application. Rather, they are merely examples that are illustrative of apparatuses and methods consistent with some aspects of the present application as detailed in the appended claims.

[0021] With the increasing demand for lightweight and high-efficiency manufacturing in the fields of low-altitude economy and new energy vehicles, the intermediate temperature prepreg has become an important intermediate for research and manufacturing due to its lower curing temperature (80-150°C). In the related technology, the curing period of the intermediate temperature prepreg is long, the energy consumption of the hot-pressing equipment forming is high, and the flowability of the prepreg in the molten state is poor, which is easy to have glue and pore defects between the prepreg layers and the surface, which has an adverse effect on the mechanical properties of the prepreg product.

[0022] Based on this, the present application provides a forming method of a prepreg, which pre-compacts a plurality of layers of prepreg through a pre-compaction device to change the flatness of the prepreg, obtains an intermediate body, places a compression mold with the intermediate body in a hot-pressing equipment, and performs a step-by-step pressurization heat treatment on the compression mold through the hot-pressing equipment, and after each pressurization treatment, performs a first vacuum extraction treatment on the intermediate body to remove the gas generated in the intermediate body during the heat treatment. The intermediate body after the heat treatment is demolded to obtain a prepreg product, thereby improving the flatness of the intermediate body, thereby reducing the pores formed by the unevenness of the intermediate body, and also through the step-by-step pressurization heat treatment and the first vacuum extraction treatment, the air in the intermediate body is quickly discharged, avoiding the air to be retained in the intermediate body to form pores, also reducing the pores in the prepreg product, and improving the mechanical properties of the prepreg product.

[0023] An exemplary embodiment of the present application provides a forming method of a prepreg, as shown in Figure 1 The forming method of the prepreg specifically includes the following steps: S100, sequentially lay a plurality of layers of prepreg in the first accommodating part of the pre-compaction device, and pre-compaction the prepreg in the first accommodating part through the pre-compaction device to change the flatness of the prepreg, and obtain an intermediate body.

[0024] In this step, as shown in Figure 5The cut multilayer prepreg is laid in the first accommodating part 11 of the pre-compaction device 1, and the prepreg in the first accommodating part 11 is subjected to pre-compaction treatment by the pre-compaction device 1. For example, the prepreg can be a carbon fiber prepreg composed of carbon fibers and a resin matrix. The first accommodating part 11 can be an accommodating bag, and the multilayer prepreg is laid in the accommodating bag in sequence. The pre-compaction treatment can be to form a negative pressure in the first accommodating part 11 by vacuumizing, and to extrude the first accommodating part 11 by the atmospheric pressure outside the first accommodating part 11, so that the first accommodating part 11 is attached to the prepreg in the first accommodating part 11, which not only reduces the residual air between the multilayer prepregs, but also changes the flatness of the prepreg, so that the laid multilayer prepreg is more flat, avoiding wrinkles in the prepreg, and further avoiding the formation of gaps between the multilayer prepregs due to wrinkles. The pre-compaction treatment can also be to flatten the prepreg by a plate-shaped object or a roller, so that the multilayer prepreg is more flat, the flatness of the prepreg is improved, the gaps between the multilayer prepregs due to wrinkles are avoided, and the air trapped in the intermediate body 13 is less.

[0025] S200, the intermediate body is taken out of the first accommodating part and placed in the second accommodating part of the pressing mold.

[0026] In this step, referring to Figure 3 and Figure 4 After the intermediate body 13 is taken out of the first accommodating part 11, the intermediate body 13 is placed in the second accommodating part 23 of the pressing mold 2. For example, the second accommodating part 23 can be a silica gel bag, which has good extensibility, easy demolding, strong wrapping plasticity, and can improve the connection strength inside the intermediate body 13 by applying pressure to the pressing mold 2 to transmit the pressure to the second accommodating part 23 and the intermediate body 13. When pressure is applied to the pressing mold 2, the pressing mold 2 is in contact with the second accommodating part 23, and the second accommodating part 23 is in contact with the intermediate body 13, which can make the pressure applied to each part of the surface of the intermediate body 13 more uniform, and can avoid the problem of more pores caused by unbalanced local stress of the intermediate body 13.

[0027] S300, the pressing mold with the intermediate body is placed in the hot-pressing equipment, and the pressing mold is subjected to step-by-step pressure increasing hot-pressing treatment by the hot-pressing equipment, and after each pressure increasing treatment, the intermediate body in the second accommodating part is subjected to first vacuumizing treatment to remove the gas generated in the intermediate body during the hot-pressing treatment.

[0028] In this step, referring to Figure 3 and Figure 4, by step-by-step pressurization, the pressure received by the compression mold 2 at the beginning is small, most of the air in the intermediate body 13 can be discharged, and the problem that the air cannot be discharged in time and remains in the intermediate body 13 due to a large initial pressure is avoided. Subsequent hot pressing treatment and increasing pressure can accelerate the flow of resin in a molten state, allowing the resin to flow into the pores of the fiber tows, avoiding local lack of resin and reducing residual air bubbles, and making the internal combination of the intermediate body 13 more compact. The first vacuumizing treatment is performed on the intermediate body 13 located in the second accommodating portion 23 at the same time of the pressurization treatment, further removing the gas generated in the intermediate body 13 during the hot pressing treatment, reducing the residual air in the intermediate body 13, making the pores in the intermediate body 13 less, and making the structural strength of the intermediate body 13 higher and the mechanical properties better.

[0029] S400, the intermediate body after the hot pressing treatment is demolded to obtain a prepreg product.

[0030] In this step, the intermediate body 13 after hot pressing is taken out of the compression mold 2. Since the intermediate body 13 is placed in the second accommodating portion 23, the second accommodating portion 23 is detachably arranged in the compression mold 2. Taking the second accommodating portion 23 out of the compression mold 2 can facilitate the demolding of the intermediate body 13 and the compression mold 2, and the intermediate body 13 is taken out of the second accommodating portion 23 to obtain a prepreg product.

[0031] In this embodiment, the multi-layer prepreg is pre-compacted by the pre-compaction device 1 to change the flatness of the prepreg and obtain the intermediate body 13. The compression mold 2 with the intermediate body 13 is placed in a hot pressing equipment, and the compression mold 2 is subjected to step-by-step hot pressing treatment by the hot pressing equipment. After each pressurization treatment, the first vacuumizing treatment is performed on the intermediate body 13 to remove the gas generated in the intermediate body 13 during the hot pressing treatment. The intermediate body 13 after the hot pressing treatment is demolded to obtain a prepreg product. By pre-compacting the multi-layer prepreg before hot pressing treatment to change the flatness of the prepreg, the multi-layer prepreg laid is more flat, avoiding wrinkles in the prepreg, and further avoiding air gaps between the multi-layer prepregs due to wrinkles. The air trapped in the intermediate body 13 is less, which is beneficial to reduce the pores in the subsequently formed prepreg product. The step-by-step hot pressing treatment of the compression mold 2 by the hot pressing equipment is beneficial to quickly discharge the gas at the initial hot pressing treatment, avoiding the problem that the gas cannot be discharged in time due to a large pressure and is sealed inside the intermediate body 13. Further step-by-step pressurization can improve the internal combination of the intermediate body 13 after most of the gas is discharged, making the prepreg in a molten state more easily infiltrate into the cracks inside the intermediate body 13, thereby expelling the air bubbles out of the intermediate body 13, avoiding the air to be trapped inside the intermediate body 13 to form pores, thereby reducing the pores in the prepreg product after demolding, and improving the mechanical properties of the prepreg product.

[0032] In some embodiments, step S100 involves sequentially laying multiple layers of prepreg into the first receiving portion of the precompacting device, and precompacting the prepreg located in the first receiving portion using the precompacting device. This specifically includes the following steps: S110. The first layer of prepreg is placed in the first accommodating part, and the first layer of prepreg located in the first accommodating part is subjected to a second vacuum treatment by a pre-compacting device.

[0033] In this step, see Figure 2 and Figure 5 The first layer of prepreg is laid on the inner side of the bottom of the first receiving part 11. By performing a second vacuum treatment on the first layer of prepreg, a negative pressure is formed in the first receiving part 11. The atmospheric pressure outside the first receiving part 11 is used to squeeze the first receiving part 11, so that the first receiving part 11 adheres to the first layer of prepreg inside the first receiving part 11. This can change the flatness of the first layer of prepreg, making the laid first layer of prepreg flatter and avoiding the formation of wrinkles in the first layer of prepreg. This also avoids the formation of gaps between the multiple layers of prepreg laid on the first layer of prepreg due to wrinkles and protrusions. This is conducive to making the formed intermediate body 13 flatter, the layers of the intermediate body 13 adhere more tightly, and the gaps inside the intermediate body 13 are smaller.

[0034] S120. Multiple sets of prepreg are sequentially laid on the first layer of prepreg, and after each set of prepreg is laid, the prepreg located in the first accommodating part is subjected to a third vacuum treatment by a pre-compacting device. Each set of prepreg includes at least one layer of prepreg.

[0035] In this step, see Figure 2 and Figure 5 Multiple sets of prepreg are sequentially laid on the first layer of prepreg. After each set of prepreg is laid, a third vacuum treatment is performed on the prepreg located in the first receiving portion 11. This creates negative pressure within the first receiving portion 11, and the atmospheric pressure outside the first receiving portion 11 compresses the first receiving portion 11, causing it to adhere to each set of prepreg within it. This alters the flatness of each set of prepreg, making each laid set of prepreg smoother and preventing wrinkles. This avoids voids caused by wrinkles, resulting in a smoother intermediate body 13 with tighter adhesion between its layers and fewer voids within the intermediate body 13. Each set of prepreg may consist of two or three layers.

[0036] The prepreg is made of a fiber and resin composite. Exemplarily, the direction along the fiber extension is defined as 0°, the direction perpendicular to the fiber extension is defined as 90°, a 45° counterclockwise rotation along the fiber extension is defined as 45°, and a 45° clockwise rotation along the fiber extension is defined as -45°. The prepreg can be configured as nine layers, laid from bottom to top. The fiber extension directions of the first to ninth layers of prepreg are sequentially 45°, 0°, 0°, -45°, 90°, -45°, 0°, 0°, and 45°. Staggering the laying directions of at least some adjacent layers of prepreg can improve the structural strength within the intermediate 13.

[0037] In some embodiments, in step S300, the pressing mold is subjected to a step-by-step hot pressing process using a hot pressing device, and after each pressurization process, the intermediate body located in the second accommodating part is subjected to a first vacuuming process, specifically including the following steps: S310. The pressing mold is subjected to a first hot pressing treatment by using a hot pressing device with a first pressure.

[0038] In this step, see Figure 3 and Figure 4 The pressing mold 2 is placed on a hot pressing device, which applies a first pressure to perform a first hot pressing treatment on the pressing mold 2. This allows most of the air in the intermediate body 13 to be expelled, preventing gas from remaining in the intermediate body 13 due to high initial pressure, thereby reducing the porosity formed in the intermediate body 13. For example, the first pressure can be 0.01 MPa.

[0039] S320. Perform the first vacuuming process on the intermediate body in the pressing mold after the first hot pressing treatment.

[0040] In this step, see Figure 3 and Figure 4 The first vacuum process quickly removes air from intermediate 13, preventing gas from remaining in intermediate 13 and further reducing the porosity formed in intermediate 13.

[0041] S330. After the first vacuuming process, the pressing mold is subjected to a second hot pressing process using a hot pressing device with a second pressure.

[0042] In this step, see Figure 3 and Figure 4The hot pressing equipment uses a second pressure to perform a second hot pressing treatment on the pressing mold 2, and the second pressure is greater than the first pressure. By hot pressing and increasing the pressure, the flow of molten resin can be accelerated, allowing the resin to flow into the pores of the fiber bundles. The resin fully wets the fiber bundles, avoiding local resin deficiency in the intermediate body 13, filling the pores within the intermediate body 13, reducing air bubbles within the intermediate body 13, and making the internal bonding of the intermediate body 13 tighter. For example, the second pressure can be 0.6 MPa.

[0043] S340. Perform a second first vacuuming process on the intermediate body in the pressing mold after the second hot pressing treatment.

[0044] In this step, the air in the intermediate 13 can be further discharged through the second first vacuum treatment, which avoids the gas in the intermediate 13 in the pressing mold after the second hot pressing treatment from not being discharged in time and remaining in the intermediate 13, and further reduces the porosity formed in the intermediate 13.

[0045] S350, after the second vacuuming process, the pressing mold is subjected to a third hot pressing process using a third pressure through a hot pressing device.

[0046] In this step, see Figure 3 and Figure 4 The hot pressing equipment uses a third pressure to perform a third hot pressing treatment on the pressing mold 2, and the third pressure is greater than the second pressure. By hot pressing and increasing the pressure, the molten resin can flow faster, allowing the resin to fully penetrate into the pores of the fiber bundles, filling the pores in the intermediate 13, improving the discharge of gas from the intermediate 13, reducing air bubbles in the intermediate 13, and making the internal bonding of the intermediate 13 tighter and its mechanical properties better. For example, the third pressure can be 1.3 MPa.

[0047] S360, Perform a third first vacuuming process on the intermediate body in the pressing mold after the third hot pressing treatment.

[0048] In this step, the air in the intermediate body 13 can be further discharged through the third first vacuum treatment, which avoids the gas in the intermediate body 13 in the pressing mold after the third hot pressing treatment not being discharged in time and remaining in the intermediate body 13, further reducing the porosity formed in the intermediate body 13 and improving the structural strength of the intermediate body 13.

[0049] In this embodiment, the air in the intermediate 13 is gradually expelled through the stepwise pressurization hot pressing process, which reduces the residual air in the intermediate 13 and thus reduces the porosity in the intermediate 13, resulting in higher structural strength and better mechanical properties of the intermediate 13.

[0050] In some embodiments, the first pressure is less than or equal to 0.5 MPa. Under this pressure range, the air in the intermediate body 13 in the second accommodating part 23 can be quickly discharged, while avoiding the problem that the gas cannot be discharged in time due to excessive pressure and remains in the intermediate body 13, which is beneficial to reduce the porosity formed in the intermediate body 13.

[0051] The second pressure is less than or equal to 1 MPa. Under this pressure range, the air in the intermediate body 13 of the second accommodating part 23 can be discharged more quickly. At the same time, increasing the pressure can make the resin in the molten state wet the gaps in the fiber bundles in the intermediate body 13, reduce the residual air in the intermediate body 13, and thus reduce the porosity formed in the intermediate body 13.

[0052] The third pressure is less than or equal to 3 MPa. Under this pressure range, the resin in the molten state can more easily wet all parts of the intermediate 13, reduce the residual air in the intermediate 13, and thus reduce the porosity formed in the intermediate 13.

[0053] In some embodiments, the hot pressing time of each pressurization process is gradually increased. Since most of the air in the second accommodating part 23 and the intermediate body 13 is discharged during the first hot pressing process, the air discharge efficiency remaining in the intermediate body 13 is low during the second and third hot pressing processes. The gradual increase in the hot pressing time of each pressurization process can improve the air discharge efficiency remaining in the intermediate body 13, thereby reducing the porosity in the intermediate body 13, improving the structural strength of the intermediate body 13, and thus improving the mechanical properties of the prepreg product.

[0054] In some embodiments, the hot-pressing time of the third hot-pressing treatment is longer than that of the second hot-pressing treatment, and the hot-pressing time of the second hot-pressing treatment is longer than that of the first hot-pressing treatment. Specifically, the hot-pressing time of the first hot-pressing treatment is less than or equal to 5 minutes. The hot-pressing time of the second hot-pressing treatment is less than or equal to 10 minutes. The hot-pressing time of the third hot-pressing treatment is less than or equal to 60 minutes. Thus, by progressively increasing the hot-pressing time of each treatment, the efficiency of air removal from the intermediate 13 is improved, thereby reducing porosity in the intermediate 13, increasing the structural strength of the intermediate 13, and ultimately improving the mechanical properties of the prepreg product.

[0055] In some embodiments, the hot pressing temperature after each pressurization is equal. For example, the hot pressing temperature can be any value between 80°C and 150°C, which can ensure that the temperature is uniform throughout the intermediate 13, so that the density of the molten resin is more uniform throughout the intermediate 13, and prevent the local accumulation of resin in the intermediate 13 from affecting the structural performance of the intermediate 13.

[0056] In some embodiments, the prepreg molding method further includes, before placing the pressing mold 2 with the intermediate body 13 attached to a hot press, the prepreg molding method further includes: Preheating the hot press equipment allows the temperature of the intermediate 13 inside the hot press equipment to be increased rapidly when the pressing mold 2 is placed in the hot press equipment, so that the resin in the prepreg enters the melting state more quickly and improves the molding efficiency of the prepreg product.

[0057] In some embodiments, the intermediate body after hot pressing is demolded, specifically including the following steps: removing the intermediate body from the pressing mold. In this step, the temperature of the pressing mold 2 is maintained at the same temperature as during hot pressing, at which point the intermediate body 13 has a certain degree of toughness, making it easy to remove the intermediate body 13.

[0058] In this embodiment, compared to existing molding methods, the prepreg molding method described herein can significantly reduce the porosity of the prepreg product and improve its degree of curing. For example, Table 1 below shows the porosity and curing rate of prepreg products manufactured using the prepreg molding method of this embodiment. It can be seen that the average porosity of the prepreg products in this embodiment is 0.22%, and the average degree of curing is 98.37%. The lower porosity and higher degree of curing result in prepreg products with better mechanical properties obtained through the prepreg molding method described herein.

[0059] Table 1

[0060] Meanwhile, compared with existing molding methods, the prepreg products made by the prepreg molding method in this embodiment have a more uniform thickness, resulting in better mechanical properties. For example, as shown in Table 2 below, the thickness table of prepreg products made by the prepreg molding method in this embodiment shows that the standard deviation between the thicknesses at different locations of the same prepreg product made by the prepreg molding method in this embodiment is 0.017 mm, indicating that the thickness of the prepreg product is more uniform, thus giving the prepreg product better mechanical properties.

[0061] Table 2

[0062] An exemplary embodiment of this application provides a prepreg molding apparatus, see [link to example]. Figures 3-5The prepreg molding apparatus is used to implement the prepreg molding method described above. The prepreg molding apparatus includes a pre-compacting device 1, a pressing mold 2, and a hot pressing device. The pre-compacting device 1 includes a first receiving portion 11 and a pre-compacting portion. The first receiving portion 11 is used to receive the prepreg, and the first receiving portion 11 can be a receiving bag, with multiple layers of prepreg sequentially laid inside the receiving bag. The compacting portion is used to pre-compact the prepreg located in the first receiving portion 11 to change the flatness of the prepreg, obtaining an intermediate body 13. Exemplarily, the compacting portion can be a vacuum device connected to the first receiving portion 11, used to evacuate the first receiving portion 11. Pre-compaction can be achieved by creating a negative pressure within the first receiving portion 11 through vacuuming, and then using atmospheric pressure outside the first receiving portion 11 to compress it, causing the first receiving portion 11 to adhere to the prepreg within it. This not only reduces residual air between multiple layers of prepreg but also improves the flatness of the prepreg, making the laid multi-layer prepreg smoother and preventing wrinkles. This also prevents gaps caused by wrinkles between the multiple layers of prepreg. Alternatively, the compaction part can be a plate-like object or a roller. The corresponding pre-compaction process involves flattening the prepreg using a plate-like object or roller to make the multi-layer prepreg smoother, improving its flatness and preventing gaps caused by wrinkles between the multiple layers of prepreg, thus reducing the amount of air trapped within the intermediate body 13.

[0063] See Figures 3-4 The pressing mold 2 includes a first mold 21 and a second mold 22 that cooperate with each other. The second mold 22 is provided with a second receiving portion 23 and a first vacuum device connected to the second receiving portion 23. The intermediate body 13 is placed in the second receiving portion 23, which is used to melt the intermediate body 13. Exemplarily, the second receiving portion 23 is a silicone film. Silicone material has good extensibility, is easy to demold, and has strong plasticity for wrapping. The second mold 22 includes a recess 221, which, exemplarily, has a depth of 5 mm. The first mold 21 includes a protrusion 211 that matches the recess 221, which, exemplarily, has a height of 2 mm. The second receiving portion 23 is placed in the recess 221, and the protrusion 211 is inserted into the recess 221 and abuts against the second receiving portion 23. The intermediate body 13 is pressed by applying pressure to the first mold 21.

[0064] See Figures 3-4The hot pressing equipment is used to perform a step-by-step pressurization heat treatment on the pressing mold 2 with the intermediate body 13 attached. After each pressurization process, a vacuum device performs a first vacuum treatment on the intermediate body 13 located in the second accommodating part 23 to remove the gas generated in the intermediate body 13 during the hot pressing process. By gradually increasing the pressure, the initial pressure on the pressing mold 2 is relatively small, which can expel most of the air in the intermediate body 13 and prevent the gas from remaining in the intermediate body 13 due to the high initial pressure. Subsequent hot pressing and increased pressure can accelerate the flow of molten resin, allowing the resin to flow into the pores of the fiber bundles, avoiding local resin shortages and reducing residual air bubbles, resulting in a tighter internal bond in the intermediate body 13. Simultaneously with the pressurization process, the first vacuum treatment on the intermediate body 13 located in the second accommodating part 23 further removes the gas generated in the intermediate body 13 during the hot pressing process, reduces the residual air in the intermediate body 13, resulting in fewer pores in the intermediate body 13, higher structural strength, and better mechanical properties.

[0065] The prepreg molding apparatus in this embodiment helps to improve the air removal efficiency in the intermediate 13, reduce the residual air in the intermediate 13, and thus reduce the porosity formed in the intermediate 13, thereby reducing the porosity in the prepreg product after demolding and improving the mechanical properties of the prepreg product.

[0066] In some embodiments, see Figure 5 The first receiving part 11 is a receiving bag, which includes a first inner side and a second inner side opposite to each other. The first inner side is located at the bottom of the receiving bag and is used to carry the prepreg. A separation film layer 14 is provided on the first inner side, which can be a polyethylene separation film. The second inner side is located at the top of the receiving bag and is provided with a breathable film layer 12. The breathable film layer 12 can be made of breathable felt. The pre-compacted part is a second vacuum device connected to the receiving bag. For example, an air extraction valve 24 is provided between the second vacuum device and the receiving bag. The diameter of the air extraction valve 24 is less than 1 mm.

[0067] A prepreg layer is disposed between the release membrane layer 14 and the breathable membrane layer 12. The release membrane layer 14 prevents the prepreg from adhering to the bottom of the first receiving portion 11, thus serving as a barrier. The breathable felt allows air inside the first receiving portion 11 to flow through the breathable felt and be discharged from the second receiving portion 23 under the drive of the second vacuum device during the pre-compaction process. This avoids the problem of air being trapped inside the first receiving portion 11 due to its adhesion to the prepreg, which is beneficial for improving the efficiency of air discharge from the intermediate 13, reducing the number of pores formed by air remaining in the intermediate 13, thereby improving the structural strength of the intermediate 13 and the mechanical properties of the prepreg product.

[0068] In some embodiments, see Figures 3-4 The second mold 22 has a recess 221 with grooves at opposite ends. The second mold 22 also includes a gasket 25 disposed between the first mold 21 and the second mold 22 and within the grooves. At least one gasket 25 is provided in each groove. During hot pressing, the second receiving portion 23 with the intermediate body 13 is placed within the recess 221, and the protrusion is inserted into the recess 221 and abuts against the gasket 25. For example, the gasket 25 has different heights, and the thickness of the prepreg product after hot pressing is limited by adjusting the height of the gasket 25.

[0069] The prepreg molding device in this embodiment can be recycled and reused, saving costs and is easy to operate. The first mold 21 and the second mold 22 cooperate to apply uniform pressure to the intermediate body 13, thereby making the thickness of the prepreg product uniform, thus achieving the effect of high-efficiency and low-cost molding of prepreg.

[0070] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0071] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for molding a prepreg, characterized in that, The molding method of the prepreg includes: Multilayer prepregs are sequentially laid in the first receiving part of the precompacting device, and the prepregs located in the first receiving part are precompacted by the precompacting device to change the flatness of the prepregs and obtain an intermediate body. The intermediate body is removed from the first receiving portion and placed in the second receiving portion of the pressing mold; The pressing mold with the intermediate attached is placed in a hot pressing device, and the pressing mold is subjected to a step-by-step pressurization process by the hot pressing device. After each pressurization process, the intermediate located in the second accommodating part is subjected to a first vacuum process to remove the gas generated by the intermediate during the hot pressing process. The intermediate material after the hot pressing treatment is demolded to obtain a prepreg product.

2. The molding method for the prepreg according to claim 1, characterized in that, The step of sequentially laying multiple layers of prepreg in the first receiving portion of the precompacting device, and precompacting the prepreg located in the first receiving portion using the precompacting device, includes: The first layer of prepreg is placed in the first accommodating part, and the first layer of prepreg located in the first accommodating part is subjected to a second vacuum treatment by the pre-compacting device; Multiple sets of the prepreg are sequentially laid on the first layer of the prepreg, and after each set of the prepreg is laid, the prepreg located in the first accommodating part is subjected to a third vacuum treatment by the precompacting device; Each group of prepregs includes at least one layer of the prepreg.

3. The molding method for the prepreg according to claim 1, characterized in that, The hot pressing process, which involves progressively increasing the pressure of the pressing mold using the hot pressing equipment, and the subsequent vacuuming of the intermediate body located in the second accommodating portion after each pressurization process, includes: The pressing device applies a first pressure to the pressing mold to perform a first hot pressing treatment. The intermediate body in the pressing mold after the first hot pressing treatment is subjected to the first vacuum treatment. After the first vacuuming process, the pressing mold is subjected to a second hot pressing process using the hot pressing equipment under a second pressure. The intermediate body in the pressing mold after the second hot pressing treatment is subjected to the first vacuum treatment a second time. After the first vacuuming process is performed a second time, the pressing mold is subjected to a third hot pressing process using a third pressure through the hot pressing equipment. The intermediate body in the pressing mold after the third hot pressing treatment is subjected to the first vacuum treatment for the third time. Wherein, the third pressure is greater than the second pressure, and the second pressure is greater than the first pressure.

4. The molding method for the prepreg according to claim 3, characterized in that, The first pressure is less than or equal to 0.5 MPa; The second pressure is less than or equal to 1 MPa; The third pressure is less than or equal to 3 MPa.

5. The molding method for the prepreg according to claim 3, characterized in that, The hot pressing time of the hot pressing process increases progressively with each pressurization.

6. The molding method of the prepreg according to claim 5, characterized in that, The hot pressing time of the third hot pressing treatment is greater than the hot pressing time of the second hot pressing treatment, and the hot pressing time of the second hot pressing treatment is greater than the hot pressing time of the first hot pressing treatment. The hot pressing time for the first hot pressing treatment is less than or equal to 5 minutes; the hot pressing time for the second hot pressing treatment is less than or equal to 10 minutes; and the hot pressing time for the third hot pressing treatment is less than or equal to 60 minutes.

7. The molding method of the prepreg according to any one of claims 1 to 6, characterized in that, The hot pressing temperature is the same after each pressurization.

8. The molding method of the prepreg according to any one of claims 1 to 6, characterized in that, The method for forming the prepreg further includes, prior to placing the pressing mold with the intermediate attached into a hot press, the method for forming the prepreg: The hot pressing equipment is preheated.

9. A molding apparatus for prepreg, characterized in that, The prepreg molding apparatus includes: A pre-compacting device includes a first accommodating part and a pre-compacting part. The first accommodating part is used to accommodate prepreg, and the pre-compacting part is used to pre-compact the prepreg located in the first accommodating part to change the flatness of the prepreg and obtain an intermediate. A pressing mold, the pressing mold including a first mold and a second mold that cooperate with each other, the second mold being provided with a second receiving part and a first vacuum device connected to the second receiving part, the second receiving part being used to receive the intermediate body; A hot pressing device is used to perform a step-by-step hot pressing process on the pressing mold with the intermediate attached. After each pressurization process, the vacuum device performs a first vacuum process on the intermediate located in the second accommodating part to remove the gas generated by the intermediate during the hot pressing process.

10. The prepreg molding apparatus according to claim 9, characterized in that, The first receiving portion is a receiving bag, which includes a first inner side and a second inner side opposite to each other. The first inner side is used to carry the prepreg, and a separation film layer is provided on the first inner side, and a breathable film layer is provided on the second inner side. The pre-compacted section is a second vacuum device connected to the containing bag.

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