Prepreg molding compound manufacturing apparatus and method

Abstract

This disclosure provides a system and method for preparing molding compounds. The system includes a supply device, a pretreatment device, and a dispersion molding device arranged sequentially along the prepreg conveying direction. The supply device provides a roll of prepreg material. The pretreatment device includes a film removal device, a cooling device, and a chopped component sequentially along the prepreg conveying direction. The dispersion molding device includes a film-releasing assembly, a dispersion device, a compaction device, and a conveyor belt. The system provided in this disclosure is used to prepare thermosetting chopped prepreg molding compounds. The prepreg molding compounds prepared by this system have reinforcing fibers distributed in a non-preferred orientation in the plane, with a macroscopically uniform volume fraction of reinforcing fibers. Resin-rich areas and internal pore defects are effectively suppressed, local stress concentration is significantly reduced, and the mechanical properties of the molding compound are thus comprehensively improved.

Description

Technical Field

[0001] This disclosure pertains to the field of prepreg molding compounds, and specifically relates to a prepreg molding compound preparation equipment and preparation method. Background Technology

[0002] Existing film plastics, such as chopped prepreg molding compounds (CPMC), sheet molding compounds (SMC), and directed fiber preforms (DFP), suffer from problems such as random fiber orientation and uneven local fiber volume fraction distribution due to the random distribution of filament bundles. These issues can easily lead to defects such as resin-rich areas, pores, and filament interface debonding. Summary of the Invention

[0003] To address the aforementioned problems, this disclosure provides an apparatus and method for preparing prepreg molding compounds.

[0004] According to a first aspect of an exemplary embodiment of the present disclosure, a molding compound preparation system is provided, the preparation system being a thermosetting chopped prepreg molding compound preparation system, the preparation system comprising a supply device, a pretreatment device, and a dispersion molding device arranged sequentially along the prepreg conveying direction; The supply equipment is used to provide prepreg rolls; The pretreatment equipment includes, in sequence along the conveying direction of the prepreg, a film removal device, a cooling device, and a slitting device; the film removal device is used to remove the protective film from the raw material roll of the prepreg, the cooling device is used to cool the prepreg after film removal, and the slitting device is used to cut the cooled prepreg into prepreg sheets. The dispersion molding equipment includes a film unwinding assembly, a dispersing device, a compaction device, and a conveyor belt. The film unwinding assembly includes a first unwinding unit and a second unwinding unit. The first unwinding unit is located upstream of the stub-cutting device along the prepreg conveying direction and is used to release the lower film material and continuously lay the lower film material on the conveyor belt. The dispersing device is located downstream of the stub-cutting device along the prepreg conveying direction and is used to disperse the prepreg sheet on the lower film material. The second unwinding unit is located downstream of the dispersing device along the prepreg conveying direction and is used to continuously cover the upper film material over the prepreg sheet. The compaction device is located downstream of the second unwinding unit along the prepreg conveying direction and is used to press the upper film material, the prepreg sheet, and the lower film material together to form a prepreg molding compound.

[0005] In some exemplary embodiments, the preparation system further includes: a post-processing device; The post-processing equipment includes a winding device; The winding device includes a first winding unit and a second winding unit. The first winding unit is used to peel off the upper film material on the surface of the prepreg molding compound to form the prepreg molding compound. The second winding unit is used to continuously wind the prepreg molding compound into a roll.

[0006] In some exemplary embodiments, the post-processing equipment further includes an online detection device, an edge trimming device, and a traction device; The online inspection device is located downstream of the first winding unit along the prepreg conveying direction and is used to inspect the quality characteristic parameters of the prepreg molding compound; the trimming device is a cutter structure located downstream of the online inspection device along the prepreg conveying direction and is used to cut the prepreg molding compound to obtain the cut prepreg molding compound; the traction device includes a traction roller group, which is used to provide traction power for conveying the prepreg molding compound and to move the cut prepreg molding compound to the second winding unit.

[0007] In some exemplary embodiments, the film removal device is a guide roller structure; The cooling device includes a cooling platform and a pressure roller disposed on the cooling platform. The temperature of the cooling platform is -15℃ to 20℃. The short cutting device is a multi-blade structure, and the cutting length of the multi-blade structure ranges from 0.5mm to 600mm.

[0008] In some exemplary embodiments, the compaction device includes a hot compaction device and a cold compaction device arranged sequentially along the prepreg conveying direction; The hot compaction device includes upper and lower heating roller groups for heating and pressing the prepreg molding compound; the heating temperature range of the heating roller group is 25℃~450℃. The cold compaction device includes upper and lower cooling roller groups for cooling and shaping the prepreg molding compound after molding; the cooling temperature range of the cooling roller group is -15℃ to 25℃.

[0009] In some exemplary embodiments, the compaction device further includes a rolling device disposed between the heating roller group and the cooling roller group.

[0010] In some exemplary embodiments, the quality characteristic parameters of the prepreg molding compound include at least one of areal density, thickness, and appearance parameters.

[0011] In some exemplary embodiments, the upper film material includes at least one of release paper and a polyimide film; the lower film material includes at least one of release paper and a polyimide film. According to a second aspect of an exemplary embodiment of this disclosure, a method for preparing a prepreg molding compound is also provided, the method being performed by a molding compound preparation system provided in an exemplary embodiment of this disclosure, the method comprising: Raw material rolls for prepreg are provided; Remove the surface film from the raw material roll of the prepreg, cool the prepreg after film removal, and cut the cooled prepreg into prepreg sheets; Release the lower membrane material and continuously lay it on the conveyor belt. Disperse the prepreg sheet on the lower membrane material and continuously cover it with an upper membrane material. Press the upper membrane material, the prepreg sheet and the lower membrane material together to form a preliminary prepreg molding compound.

[0012] In some exemplary embodiments, the preparation method further includes: Peel off the upper film material from the surface of the initial prepreg molding compound; The quality characteristic parameters of the preliminary prepreg molding compound after the upper membrane material has been peeled off are detected. The preliminary prepreg molding compound is cut and peeled off from the upper membrane material to form the prepreg molding compound; The prepreg molding compound is continuously wound into a roll. The molding compound preparation system provided in this disclosure, by placing the second unwinding unit downstream of the dispersing device along the prepreg conveying direction, allows the upper film material to immediately cover the prepreg sheet after dispersion, and works in conjunction with the lower film material to lock the random distribution pattern of the prepreg sheet, ensuring that this distribution pattern is completely maintained during subsequent conveying and compaction. Simultaneously, the upper and lower film materials act as an isolation layer, effectively preventing the resin matrix from directly contacting and adhering to the surface of the pressure rollers in the compaction device; and as a pressure transmission medium, ensuring that mechanical pressure is uniformly applied to the entire prepreg sheet, thereby guaranteeing a consistent thickness and dense structure in the prepreg molding compound. Based on the complete maintenance of the random distribution pattern of the prepreg sheet and uniform compaction, the final prepreg molding compound exhibits a non-preferred orientation distribution in the plane, with a macroscopically uniform overall volume fraction of reinforcing fibers. Resin-rich areas and internal pore defects are effectively suppressed, local stress concentration is significantly reduced, and the mechanical properties of the molding compound are thus comprehensively improved.

[0013] Other features and advantages of this disclosure will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the disclosure. The objects and other advantages of this disclosure may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this disclosure or 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 some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A process flow diagram of the prepreg molding compound preparation equipment provided in the embodiments of this disclosure.

[0016] Figure 2 A block diagram of a prepreg molding compound preparation apparatus provided in an embodiment of this disclosure.

[0017] Figure 3 This is a schematic flowchart of a method for preparing prepreg molding compounds according to an embodiment of this disclosure.

[0018] Figure label: 100. Supply equipment; 101. Workstation; 200. Pre-treatment equipment; 300. Dispersion molding equipment; 400. Post-treatment equipment; 201. Film removal device; 202. Cooling device; 203. Shortening device; 301. Film unwinding assembly; 301a. First unwinding unit; 301b. Second unwinding unit; 302. Dispersion device; 303. Compacting device; 303a. Hot compaction device; 303b. Cold compaction device; 303c. Roller pressing device; 304. Conveyor belt; 401. Winding device; 401a. First winding unit; 401b. Second winding unit; 402. Online detection device; 403. Edge trimming device; 404. Traction device. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0020] In related technologies, film plastics, such as chopped prepreg molding compounds (CPMC), sheet molding compounds (SMC), and directed fiber preforms (DFP), exhibit significant microstructural inhomogeneity during compression molding due to the random distribution of prepreg filaments. For example, the random orientation of fiber filaments within a plane and the uneven distribution of local fiber volume fraction lead to defects such as resin-rich areas, pores, filament interface debonding, and pull-out within the composite material. The main reasons for this are inconsistent prepreg filament sizes, irregular filament distribution after cutting, and a lack of effective control over the surface density and thickness uniformity of the prepreg. Particularly in the preparation of chopped prepreg molding compounds (CPMC), if uniform cutting of filament sizes and online monitoring of prepreg molding quality cannot be achieved, it will be difficult to eliminate performance fluctuations caused by uneven local fiber volume fraction, thus affecting the reliability and consistency of the composite parts.

[0021] Based on this, the present disclosure provides a molding compound preparation system. The preparation system is a thermosetting chopped prepreg molding compound preparation system. By setting the second unwinding unit downstream of the dispersing device along the prepreg conveying direction, the upper film material is immediately covered after the prepreg sheet is dispersed, and works in conjunction with the lower film material to lock the random distribution pattern of the prepreg sheet, ensuring that the distribution pattern is completely maintained during subsequent conveying and compaction.

[0022] During the compaction process, the upper and lower membrane materials serve as an isolation layer to effectively prevent the resin matrix from directly contacting and adhering to the surface of the pressure roller in the compaction device. On the other hand, they serve as a pressure transmission medium to ensure that mechanical pressure is applied evenly to the entire area of ​​the prepreg sheet, thereby ensuring that the prepreg molding compound has a consistent thickness and a dense structure.

[0023] Based on the complete preservation and uniform compaction of the random distribution pattern of the prepreg sheets, the reinforcing fibers in the final prepreg molding compound are distributed in a non-preferred orientation in the plane, the overall volume fraction of reinforcing fibers is macroscopically uniform, and the resin-rich areas and internal pore defects are effectively suppressed.

[0024] Figure 1 This is a schematic diagram of the molding compound preparation system provided in the embodiments of this disclosure. Figure 2 A block diagram of the molding compound preparation system provided in the embodiments of this disclosure, such as... Figure 1 and Figure 2 As shown, the molding compound preparation system includes a supply device 100, a pretreatment device 200, and a dispersion molding device 300 arranged sequentially along the prepreg conveying direction.

[0025] The supply device 100 may be a conveyor structure for providing continuous rolls of prepreg. The prepreg rolls include prepreg and protective films on the upper and lower surfaces of the prepreg, an upper protective film and a lower protective film. The prepreg includes reinforcing fibers and a resin matrix.

[0026] The pretreatment equipment 200 includes, in sequence along the prepreg conveying direction, a film removal device 201, a cooling device 202, and a shaving device 203.

[0027] The film removal device 201 is used to remove the protective film from the prepreg roll. In some embodiments, the surface of the prepreg roll is covered with a protective film, which includes an upper protective film and a lower protective film, to prevent mechanical damage and / or chemical corrosion and contamination of the prepreg. The material of the protective film can be any material that can protect the prepreg; for example, the materials of the upper and lower protective films can be release paper or polyethylene film (PE film), respectively. Since the prepreg roll includes a protective film, the film removal device 201 removes the protective film during the preparation of the prepreg molding compound to facilitate subsequent preparation of the prepreg molding compound.

[0028] Cooling device 202 is used to cool the prepreg after film removal, and slitting device 203 is used to cut the cooled prepreg into prepreg sheets.

[0029] This embodiment of the invention provides a cooling device 202 upstream of the chopped prepreg conveying direction in the chopped prepreg device 203. This cooling device allows the prepreg after film removal to be cooled before cutting, thereby making the resin matrix in the prepreg brittle and reducing its viscosity. As a result, during cutting by the chopped prepreg device 203, the brittled prepreg does not adhere to the cutter blade, the cut surface is flat, and the resulting prepreg sheets are independent of each other, do not stick together, and have regular geometric dimensions and good dispersibility.

[0030] The term "upstream" in "upstream of the cooling device 202" refers to the upstream location along the prepreg conveying direction. For example, in this embodiment, the cooling device 202 is located upstream of the shaving device 203 along the prepreg conveying direction. To fully maintain the characteristics of the brittle prepreg, the outlet of the cooling device 202 and the inlet of the shaving device 203 can be connected end-to-end by a conveyor belt, so that the prepreg directly enters the shaving device 203 after leaving the cooling device 202, and is then cut into prepreg sheets by the shaving device 203.

[0031] The dispersion molding module 300 includes a film unwinding assembly 301, a dispersion device 302, a compaction device 303, and a conveyor belt 304. The film unwinding assembly 301 includes a first unwinding unit 301a and a second unwinding unit 301b. The first unwinding unit 301a is located upstream of the stubbed device 203 along the prepreg conveying direction and is used to release the lower film material and continuously lay the lower film material on the conveyor belt 304.

[0032] In this embodiment of the disclosure, the lower membrane material includes release paper or polyethylene film (PE film).

[0033] The dispersing device 302 is located downstream of the slitting device 203 along the prepreg conveying direction and is used to disperse the prepreg sheet onto the lower film material, for example, to uniformly disperse the prepreg sheet onto the lower film material. The second unwinding unit 301b is located downstream of the dispersing device 302 along the prepreg conveying direction and is used to continuously cover the upper film material over the prepreg sheet. The upper film material includes release paper or polyethylene film (PE film).

[0034] The compaction device 303 is located downstream of the second unwinding unit 301b along the prepreg conveying direction, and is used to press the upper film material, the prepreg sheet and the lower film material together to form a prepreg molding compound.

[0035] This disclosure arranges the second unwinding unit 301b downstream of the dispersing device 302, so that the upper film material immediately covers the prepreg after it is dispersed, and together with the lower film material, locks the random distribution pattern of the prepreg and ensures that the distribution pattern is maintained intact during the conveying and compaction process.

[0036] During the compaction process, the upper and lower membrane materials act as isolation layers and pressure transmission media, preventing the resin matrix from sticking to the rollers and ensuring uniform pressure transmission, thus guaranteeing a uniform thickness and dense structure of the prepreg molding compound. Here, "sticking to the rollers" refers to the resin adhering to the rollers in the compaction device's roller assembly.

[0037] Based on the fact that the random distribution pattern of the prepreg sheet is completely maintained and uniformly compacted, the reinforcing fibers have no preferred orientation in the prepreg molding compound surface, resulting in a macroscopically uniform volume fraction of reinforcing fibers, suppression of resin-rich areas and pore defects, reduction of local stress concentration, and significant improvement in mechanical properties.

[0038] Among them, non-preferred orientation means that the reinforcing fibers in the prepreg molding compound (i.e., the XY plane formed by the length and width directions) no longer concentrate in a certain direction, but the distribution probability in each direction tends to be equal.

[0039] The resin-rich zone refers to a localized area in a prepreg molding compound where the content of reinforcing fibers is far below the average, while the resin matrix is ​​abundant, forming a continuous or large-scale accumulation of pure resin matrix.

[0040] Pore ​​defects refer to tiny voids or bubbles that exist inside prepreg molding compounds.

[0041] In this embodiment of the disclosure, the prepreg molding compound preparation system further includes a post-processing device 400.

[0042] The post-processing equipment 400 includes a winding device 401. The winding device 401 includes a first winding unit 401a and a second winding unit 401b. The first winding unit 401a is used to peel off the upper film material from the surface of the prepreg molding compound. The second winding unit 401b is used to continuously wind the finished prepreg molding compound output by the traction device 404 into a roll. In an exemplary embodiment of this disclosure, by setting the second winding unit 401b, the finished prepreg molding compound is continuously and automatically wound into a regular roll, achieving efficient collection and standardized output of the finished product.

[0043] The upper membrane material, which serves as an isolation layer for the prepreg plastic film, is removed before the final winding, leaving only the lower membrane material. This not only protects and isolates the prepreg plastic film but also facilitates its use.

[0044] In this embodiment of the disclosure, the post-processing equipment 400 of the prepreg molding compound preparation system further includes an online detection device 402, an edge trimming device 403, and a traction device 404.

[0045] The online inspection device 402 is located downstream of the first winding unit 401a along the prepreg conveying direction and is used to inspect the quality characteristic parameters of the prepreg molding compound. These quality performance parameters can be parameters describing the quality properties of the prepreg molding compound, such as at least one of the areal density, thickness, and appearance parameters. In this embodiment, the online inspection device 402 is an inspection instrument that detects the areal density of the prepreg molding compound with an accuracy of ±2 g / m² and the thickness with an accuracy of ±0.1 mm.

[0046] The trimming device 403 is a cutting structure located downstream of the online detection device 402 along the prepreg conveying direction. It is used to cut the prepreg molding compound to obtain the cut prepreg molding compound. For example, the trimming device 403 is a disc cutter structure. According to the product requirements of the prepreg molding compound, the trimming device 403 performs edge trimming to obtain the required width of the prepreg molding compound, for example, the cutting width can be 500mm.

[0047] In an exemplary embodiment of this disclosure, the edge portions on both sides of the width direction of the prepreg molding compound are removed by the edge trimming device 403. This not only eliminates the mechanically weak areas and stress concentration sources formed at the edges of the prepreg molding compound due to the absence of reinforcing fibers or the enrichment of resin matrix, but also improves the crack resistance of the edges of the finished prepreg molding compound.

[0048] The traction device 404 includes a traction roller assembly for providing traction power for conveying the cut prepreg molding compound and for conveying the cut prepreg molding compound to the second winding unit 401b.

[0049] In an exemplary embodiment of this disclosure, the traction device 404 includes a set of traction rollers arranged vertically. By providing the traction device 404 with the vertically arranged, i.e., vertically opposed, traction rollers, active traction power is provided for conveying the cut prepreg molding compound, enabling the prepreg roll to travel at a set speed uniformly and stably, avoiding the accumulation, stretching, or wrinkling of the prepreg roll due to speed mismatch. At the same time, the vertically opposed traction roller structure of the traction device 404 evenly transmits the traction force in the width direction, which can avoid surface indentations and fiber damage to the prepreg roll due to localized stress.

[0050] In this embodiment of the disclosure, the supply device 100 is provided with at least one independent conveyor 101 for placing at least one continuous roll of prepreg raw material.

[0051] Based on this embodiment, the supply equipment 100 in this disclosure can be provided with only one independent conveyor frame 101, or it can be provided with multiple independent conveyor frames 101. For example, in one example, the supply equipment 100 is provided with six independent conveyor frames 101. The six independent conveyor frames 101 can simultaneously supply continuous rolls of prepreg material to subsequent processes, which can significantly increase the total amount of raw material supplied per unit time, thereby effectively improving the production capacity and efficiency of prepreg molding compound preparation.

[0052] Furthermore, when the prepreg rolls in one of the six independent conveyor frames 101 are exhausted, the other independent conveyor frames 101 can seamlessly continue to supply prepreg rolls, thereby ensuring the continuity and stability of the raw material supply process.

[0053] In an exemplary embodiment of this disclosure, the film removal device 201 may be a guide roller structure located downstream of the supply device 100 along the prepreg conveying direction.

[0054] The film removal device 201 achieves non-destructive peeling of the protective film from the prepreg roll through the tension guiding action of the guide rollers, avoiding scratch damage to the prepreg and ensuring the integrity and flatness of the prepreg surface after film removal. Simultaneously, this arrangement allows the prepreg to immediately enter the cooling device 202 after film removal, effectively shortening the exposure time of the prepreg surface and reducing the risk of dust and impurity contamination. Furthermore, the guide roller structure is simple and reliable, requiring no external power, reducing equipment manufacturing costs and operating energy consumption, and facilitating a compact layout for the entire production line.

[0055] The cooling device 202 includes a cooling platform and a pressure roller disposed on the cooling platform, located downstream of the film removal device 201 along the prepreg conveying direction. In the exemplary embodiments of this disclosure, the temperature range of the cooling platform is -15°C to 20°C. Specifically, the temperature of the cooling platform can be -10°C, -8°C, -5°C, 0°C, 4°C, 7°C, 10°C, 12°C, or 15°C. The temperature of the cooling platform can also be any value between these exemplary temperatures, for example, -8°C to 7°C. For instance, in a specific example, the cooling platform in the cooling device 202 can be a water-cooled cooling platform with a temperature range of 5°C to 12°C.

[0056] In this embodiment, the slitting device 203 is a multi-blade structure located downstream of the cooling device 202 along the prepreg conveying direction. The cutting length of the multi-blade structure ranges from 0.5mm to 600mm.

[0057] For example, in some embodiments, the cutting length of the blade assembly can be 1mm, 10mm, 50mm, 100mm, 120mm, 180mm, 200mm, 220mm, 260mm, 300mm, 380mm, 450mm, 470mm, or 500mm. The cutting length of the blade assembly can be any value between the exemplary cutting lengths of the blade assembly, for example, the cutting length of the blade assembly can be 50mm to 380mm.

[0058] The cutting speed of the slitting device 203 can be adjusted according to production needs, which will not be elaborated here.

[0059] In some embodiments, the compaction device 303 includes a hot compaction device 303a and a cold compaction device 303b arranged sequentially along the prepreg conveying direction, and the compaction device 303 is located downstream of the second unwinding unit 301b along the prepreg conveying direction.

[0060] The hot compaction apparatus 303a includes upper and lower heating roller groups for heating and pressing prepreg molding compounds. The heating temperature range of the heating roller groups is 25°C to 450°C. For example, in some embodiments, the heating temperature of the heating roller groups can be 30°C, 50°C, 70°C, 90°C, 120°C, 180°C, 230°C, 280°C, 300°C, 320°C, 360°C, 390°C, or 400°C. The heating temperature of the heating roller groups can also be any value within the exemplary temperature range, for example, 70°C to 230°C.

[0061] During the heating and pressing process of the heating roller assembly, the pressure range can be from 0.2 MPa to 25.3 MPa. For example, in some embodiments, the pressure range can be 0.5 MPa, 1.2 MPa, 3.7 MPa, 6.5 MPa, 11.3 MPa, 15.9 MPa, 18.6 MPa, 19.7 MPa, or 22.1 MPa. The pressure range can also be any value between exemplary pressures, such as 3.7 MPa to 18.6 MPa. For example, in an exemplary example, the heating temperature of the hot compaction device 303a is 60°C, and the compaction pressure is 0.2 MPa.

[0062] The cold compaction device 303b includes upper and lower cooling roller groups for cooling and shaping the prepreg molding compound. The cooling temperature range of the cooling roller groups is -15°C to 25°C. For example, in some embodiments, the cooling temperature of the cooling roller groups can be -10°C, -8°C, -5°C, 0°C, 4°C, 7°C, 10°C, 12°C, or 15°C. The cooling temperature of the cooling roller groups can also be any value within the exemplary temperature range, for example, -5°C to 12°C.

[0063] During the cooling and forming process of the cooling roller assembly, the pressure range can be from 0.05 MPa to 13.5 MPa. For example, in some embodiments, the pressure range can be 0.09 MPa, 1.4 MPa, 2.9 MPa, 4.6 MPa, 6.7 MPa, 8.1 MPa, 9.7 MPa, 11.0 MPa, or 12.6 MPa. The pressure range can also be any value between exemplary pressures, such as 2.9 MPa to 9.7 MPa. For example, in an exemplary example, the cold compaction device 303b includes upper and lower counter-pressing water-cooled cooling rollers, the cooling temperature of which is 15°C, and the compaction pressure is 0.1 MPa.

[0064] In this disclosure, the compaction device 303 includes a hot compaction device 303a and a cold compaction device 303b. The hot compaction device 303a heats and presses the prepreg molding compound by means of a set of upper and lower pressing heated rollers, so that the resin matrix fully impregnates the reinforcing fibers and eliminates interlayer interfaces and pores, forming a uniform and dense internal structure.

[0065] The cold compaction device 303b applies pressure and cools the molded molding compound using upper and lower opposing cooling rollers, quickly locking in the thickness and density obtained from hot pressing to prevent cooling rebound and warping deformation. Simultaneously, the compaction device 303 is positioned downstream of the second unwinding unit 401b along the prepreg conveying direction, allowing the upper and lower film materials to act as an isolation layer during hot pressing, effectively preventing the resin matrix from sticking to the rollers and ensuring uniform pressure transmission.

[0066] The embodiments disclosed herein ensure the thickness accuracy, structural density, surface finish, and batch-to-batch dimensional consistency of prepreg molding compounds through a continuous process of "hot pressing followed by cold pressing".

[0067] In an exemplary embodiment of this disclosure, the compaction device 303 further includes a roller pressing device 303c disposed between the hot compaction device 303a and the cold compaction device 303b. The roller pressing device 303c is disposed after the hot compaction device 303a, allowing the prepreg molding compound to further enhance the wetting of reinforcing fibers, eliminate interlayer interfaces and pores, and further improve the uniformity and density of the internal structure of the prepreg molding compound after heating and pressurization. In some embodiments, the quality characteristic parameters of the prepreg molding compound include at least one of areal density, thickness, and appearance parameters. In an exemplary embodiment of this disclosure, to monitor the relevant preparation quality during the preparation of the prepreg molding compound, an online monitoring device 402 is provided in the prepreg molding compound preparation system to detect the quality characteristic parameters of the prepreg molding compound. The quality characteristic parameters can be any parameters describing the quality of the prepreg molding compound. The areal density of the prepreg molding compound prepared by the molding compound preparation system provided in the exemplary embodiments of this disclosure can reach 100 g / m³. 2 -10000g / m 2 Appearance parameters, such as thickness and / or width, can be determined according to product requirements. For example, the thickness can be controlled between 0.1 and 10 mm, and the width can be controlled between 300 mm and 1500 mm.

[0068] In some embodiments, the materials of the upper and lower membrane materials can be set as needed, as long as they can achieve the function of isolating and protecting the prepreg. For example, the upper membrane material may include at least one of release paper and polyimide film (PI film); the lower membrane material may include at least one of release paper and polyimide film (PI film).

[0069] Figure 3 This is a schematic flowchart of the method for preparing prepreg molding compounds provided in the embodiments of this disclosure, as shown below. Figure 3 As shown, the preparation method includes: S100, Providing raw material rolls for prepreg.

[0070] S200: Remove the surface film from the raw material roll of prepreg, cool the prepreg after film removal, and cut the cooled prepreg into prepreg sheets.

[0071] This embodiment of the invention embrittles and reduces the viscosity of the resin matrix by subjecting the prepreg after defilming to a cooling treatment before cutting. As a result, the embrittled prepreg does not adhere to the cutter and the cut surface is flat. The resulting prepreg sheets are independent of each other, do not stick together, and have regular geometric dimensions and good dispersibility.

[0072] S300: Release the lower membrane material and continuously lay it on the conveyor belt. Distribute the prepreg sheet on the lower membrane material and continuously cover it with the upper membrane material. Press the upper membrane material, the prepreg sheet and the lower membrane material together to form a preliminary prepreg molding compound.

[0073] The upper membrane material covers the prepreg sheets immediately after they are dispersed, and together with the lower membrane material, locks in the random distribution pattern of the prepreg sheets and ensures that the distribution pattern is maintained intact during the conveying and compaction process.

[0074] During the compaction process, the upper and lower membrane materials act as isolation layers and pressure transmission media, preventing the resin matrix from sticking to the rollers and ensuring uniform pressure transmission, thus guaranteeing a uniform thickness and dense structure of the prepreg molding compound. Here, "sticking to the rollers" refers to the resin adhering to the rollers in the compaction device's roller assembly.

[0075] Based on the fact that the random distribution pattern of the prepreg sheet is completely maintained and uniformly compacted, the reinforcing fibers have no preferred orientation in the prepreg molding compound surface, resulting in a macroscopically uniform volume fraction of reinforcing fibers, suppression of resin-rich areas and pore defects, reduction of local stress concentration, and significant improvement in mechanical properties.

[0076] In some embodiments, the preparation method further includes: S400: Peel off the upper film from the surface of the preliminary prepreg molding compound. The upper film may include release paper or polyethylene film (PE film).

[0077] S500, Inspect the quality characteristic parameters of the preliminary prepreg molding compound after peeling off the upper film. The quality characteristic parameters of the prepreg molding compound include at least one of areal density, thickness, and appearance parameters.

[0078] S600, cut and peel off the upper membrane material to form the prepreg molding compound.

[0079] The exemplary embodiments of this disclosure use an edge trimming device to remove the edge portions on both sides of the prepreg molding compound in the width direction. This not only eliminates the mechanically weak areas and stress concentration sources formed at the edges of the prepreg molding compound due to the absence of reinforcing fibers or the enrichment of resin matrix, but also improves the crack resistance of the edges of the finished prepreg molding compound.

[0080] In an exemplary embodiment of this disclosure, a traction device 404, including a set of upper and lower counter-pressing traction rollers, is provided to provide active traction power for conveying prepreg molding compound. This enables the prepreg material roll to travel at a set speed in a uniform and stable manner, avoiding the accumulation, stretching, or wrinkling of the prepreg material roll due to speed mismatch.

[0081] Meanwhile, the upper and lower counter-pressure traction roller group structure of the traction device 404 evenly transmits the traction force to the width direction, which can avoid surface indentations and fiber damage caused by local stress on the prepreg raw material roll.

[0082] The second winding unit 401b is used to continuously wind the prepreg molding compound output by the traction device 404 into a roll.

[0083] S800: Continuously wind prepreg molding compound into rolls.

[0084] In an exemplary embodiment of this disclosure, by setting a second winding unit 401b, prepreg molding compound is continuously and automatically wound into a regular roll, thereby achieving efficient collection and standardized output of finished products.

[0085] In the exemplary embodiments of this disclosure, the transmission speed of the entire preparation process can be determined as needed, for example, it can be transmitted at a speed of 3-15 m / min.

[0086] Exemplary embodiments of this disclosure provide a method for preparing molding compounds using the molding compound preparation system provided herein. A prepreg sheet is dispersed onto a lower film material, and an upper film material is immediately applied to cover the dispersed prepreg sheet, working in conjunction with the lower film material to lock the random distribution pattern of the prepreg sheet, ensuring that this distribution pattern is maintained intact during subsequent conveying and compaction. Simultaneously, the upper film material, the prepreg sheet, and the lower film material are pressed together. The upper and lower film materials act as an isolation layer, effectively preventing the resin matrix from directly contacting and adhering to the surface of the pressure rollers in the compaction device. They also act as a pressure transmission medium, ensuring that mechanical pressure is uniformly applied to the entire prepreg sheet, thereby guaranteeing a consistent thickness and dense structure in the prepreg molding compound. Based on the complete preservation and uniform compaction of the random distribution pattern of the prepreg sheets, the reinforcing fibers in the final prepreg molding compound are distributed in a non-preferred orientation in the plane, the overall volume fraction of reinforcing fibers is macroscopically uniform, the resin-rich area and internal pore defects are effectively suppressed, local stress concentration is significantly reduced, and the mechanical properties of the molding compound are thus comprehensively improved.

[0087] For ease of explanation, certain steps of the above method are described in relation to modules. It should be understood that the corresponding module performing one or more steps of the above method may be one or more hardware modules specifically configured to perform the corresponding step, or implemented by a processor configured to perform the corresponding step, or stored in a computer-readable medium for implementation by a processor, or implemented by some combination thereof.

[0088] The specific implementation of each module in the above-mentioned device can be referred to the implementation process of the corresponding steps in the above-mentioned method implementation method of this disclosure, and will not be repeated here.

[0089] Although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A system for preparing molding compound, characterized in that, The preparation system is a preparation system for thermosetting chopped prepreg molding compound, and the preparation system includes a supply device, a pretreatment device and a dispersion molding device arranged sequentially along the prepreg conveying direction; The supply equipment is used to provide prepreg rolls; The pretreatment equipment includes, in sequence along the conveying direction of the prepreg, a film removal device, a cooling device, and a slitting device; the film removal device is used to remove the protective film from the raw material roll of the prepreg, the cooling device is used to cool the prepreg after film removal, and the slitting device is used to cut the cooled prepreg into prepreg sheets. The dispersion molding equipment includes a film unwinding assembly, a dispersing device, a compaction device, and a conveyor belt. The film unwinding assembly includes a first unwinding unit and a second unwinding unit. The first unwinding unit is located upstream of the stub-cutting device along the prepreg conveying direction and is used to release the lower film material and continuously lay the lower film material on the conveyor belt. The dispersing device is located downstream of the stub-cutting device along the prepreg conveying direction and is used to disperse the prepreg sheet on the lower film material. The second unwinding unit is located downstream of the dispersing device along the prepreg conveying direction and is used to continuously cover the upper film material over the prepreg sheet. The compaction device is located downstream of the second unwinding unit along the prepreg conveying direction and is used to press the upper film material, the prepreg sheet, and the lower film material together to form a prepreg molding compound.

2. The molding compound preparation system according to claim 1, characterized in that, The preparation system further includes: post-processing equipment; The post-processing equipment includes a winding device; The winding device includes a first winding unit and a second winding unit. The first winding unit is used to peel off the upper film material on the surface of the prepreg molding compound to form the prepreg molding compound. The second winding unit is used to continuously wind the prepreg molding compound into a roll.

3. The molding compound preparation system according to claim 2, characterized in that, The post-processing equipment also includes an online detection device, an edge trimming device, and a traction device; The online inspection device is located downstream of the first winding unit along the prepreg conveying direction and is used to inspect the quality characteristic parameters of the prepreg molding compound; the trimming device is a cutter structure located downstream of the online inspection device along the prepreg conveying direction and is used to cut the prepreg molding compound to obtain the cut prepreg molding compound; the traction device includes a traction roller group, which is used to provide traction power for conveying the prepreg molding compound and to move the cut prepreg molding compound to the second winding unit.

4. The molding compound preparation system according to claim 1, characterized in that, The film removal device has a guide roller structure; The cooling device includes a cooling platform and a pressure roller disposed on the cooling platform. The temperature of the cooling platform is -15℃ to 20℃. The short cutting device is a multi-blade structure, and the cutting length of the multi-blade structure ranges from 0.5mm to 600mm.

5. The molding compound preparation system according to claim 1, characterized in that, The compaction device includes a hot compaction device and a cold compaction device arranged sequentially along the conveying direction of the prepreg. The hot compaction device includes upper and lower heating roller groups for heating and pressing the prepreg molding compound; the heating temperature range of the heating roller group is 25℃~450℃. The cold compaction device includes upper and lower cooling roller groups for cooling and shaping the prepreg molding compound after molding; the cooling temperature range of the cooling roller group is -15℃ to 25℃.

6. The molding compound preparation system according to claim 5, characterized in that, The compaction device also includes a roller pressing device disposed between the heating roller group and the cooling roller group.

7. The molding compound preparation system according to claim 3, characterized in that, The quality characteristic parameters of the prepreg molding compound include at least one of areal density, thickness, and appearance parameters.

8. The molding compound preparation system according to claim 1, characterized in that, The upper film material includes at least one of release paper and polyimide film; the lower film material includes at least one of release paper and polyimide film.

9. A method for preparing a molding compound, characterized in that, The preparation method is performed by the molding compound preparation system according to any one of claims 1-8, and the preparation method includes: Raw material rolls for prepreg are provided; Remove the surface film from the raw material roll of the prepreg, cool the prepreg after film removal, and cut the cooled prepreg into prepreg sheets; Release the lower membrane material and continuously lay it on the conveyor belt. Disperse the prepreg sheet on the lower membrane material and continuously cover it with an upper membrane material. Press the upper membrane material, the prepreg sheet and the lower membrane material together to form a preliminary prepreg molding compound.

10. The method for preparing molding compound according to claim 9, characterized in that, The preparation method further includes: Peel off the upper film material from the surface of the initial prepreg molding compound; The quality characteristic parameters of the preliminary prepreg molding compound after the upper membrane material has been peeled off are detected. The preliminary prepreg molding compound is cut and peeled off from the upper membrane material to form the prepreg molding compound; The prepreg molding compound is continuously wound into a roll.

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