A method of preparing a thermoplastic prepreg

Abstract

The application discloses a preparation method of a thermoplastic prepreg, and the method comprises the following steps: obtaining material information of a prepreg to be prepared, wherein the material information at least comprises material of a matrix phase and a reinforcing phase, material parameters of the reinforcing phase, and laying parameters; obtaining the area density of the matrix phase according to the material of the matrix phase and the reinforcing phase, the material parameters of the reinforcing phase, and the laying parameters; obtaining stress requirements of a composite material, and setting the fiber orientation of the reinforcing phase according to the stress requirements of the composite material; setting a paving path according to the fiber orientation of the reinforcing phase, performing paving according to the paving path, and impregnating a product after paving to obtain the prepreg. The application can solve the problems of low raw material utilization and poor designability existing in the existing impregnation method, and has the advantages of strong designability, convenient variety switching, low raw material loss and the like.

Description

Technical Field

[0001] This application relates to the field of prepreg molding technology, and in particular to a method for preparing thermoplastic prepregs. Background Technology

[0002] Prepreg refers to a resin matrix and reinforcing material impregnated under strictly controlled content conditions, resulting in a resin matrix and reinforcing material composition with uniform fiber areal density. It is an important intermediate material in the preparation of composite materials. Thermoplastic prepreg is an intermediate material prepared by combining thermoplastic resin and reinforcing material. Commonly used thermoplastic prepreg preparation processes include solution impregnation, melt impregnation, film lamination impregnation, powder impregnation, and fiber-resin mixed impregnation.

[0003] However, when using prepreg molding processes such as solution impregnation, melt impregnation, film lamination impregnation, and powder impregnation, the production line length limits the amount of process loss during prepreg preparation. In these thermoplastic prepreg production processes, the raw material only moves along the length of the equipment during operation. If reinforcing fibers are used as raw materials, the finished product is usually a unidirectional prepreg. If reinforcing fabrics are used as raw materials, the fiber arrangement direction in the reinforcing fabric is the same as the fiber arrangement direction in the final prepreg, usually orthogonal along the length and width directions, thus affecting the degree of freedom of fiber arrangement direction and making the design of fiber arrangement direction somewhat poor. Summary of the Invention

[0004] The purpose of this application is to propose a method for preparing thermoplastic prepregs, which aims to solve the problems of low raw material utilization and poor designability of existing impregnation methods.

[0005] In a first aspect, embodiments of this application provide a method for preparing a thermoplastic prepreg, the method comprising:

[0006] Obtain the material information of the prepreg to be prepared, the material information including at least the material of the matrix phase and the reinforcing phase, the material parameters of the reinforcing phase, and the layup parameters;

[0007] The areal density of the matrix phase is obtained based on the materials of the matrix phase and the reinforcing phase, the material parameters of the reinforcing phase, and the layup parameters.

[0008] Obtain the stress requirements of the composite material, and set the fiber orientation of the reinforcing phase according to the stress requirements of the composite material;

[0009] The stitching path is set according to the fiber orientation of the reinforcing phase, and stitching is performed according to the stitching path. The stitched product is then impregnated to obtain a prepreg.

[0010] Preferably, the step of obtaining the areal density of the matrix phase based on the materials of the matrix phase and the reinforcing phase, the material parameters of the reinforcing phase, and the layup parameters includes:

[0011] The material parameters of the reinforcing phase include linear density and mass percentage. The areal density of the fiber layer after laying is calculated according to the following formula:

[0012] ρ1=ρ0 / d

[0013] Where ρ1 represents the areal density of the fiber layer after laying, ρ0 represents the linear density of the reinforcing phase, and d represents the laying parameters.

[0014] Preferably, the step of obtaining the areal density of the matrix phase based on the materials of the matrix phase and the reinforcing phase, the material parameters of the reinforcing phase, and the layup parameters includes:

[0015] The areal density of the matrix phase is calculated using the following formula:

[0016] ρ2=ρ1(1-w1) / w1

[0017] Wherein, ρ2 represents the areal density of the matrix phase, and w1 represents the mass percentage of the reinforcing phase in the prepreg.

[0018] Preferably, in the step of obtaining the stress requirements of the composite material and setting the fiber orientation of the reinforcing phase according to the stress requirements of the composite material:

[0019] The fiber orientation includes at least one of the following: circumferential, first preset angle, second preset angle, third preset angle, and fourth preset angle.

[0020] Preferably, the step of obtaining the stress requirements of the composite material and setting the fiber orientation of the reinforcing phase according to the stress requirements of the composite material includes:

[0021] In setting the fiber orientation, the area where the fiber bends is located on the outside of the product.

[0022] Preferably, the step of setting the stitching path according to the fiber orientation of the reinforcing phase includes:

[0023] If the fiber orientation is circumferential, then equidistant spiral stitching is used, and the pitch spacing is obtained according to the laying parameters.

[0024] Preferably, in the step of obtaining the material information of the prepreg to be prepared:

[0025] The matrix phase material includes at least one of ultra-high molecular weight polyethylene, nylon, aramid, ultra-high molecular weight polypropylene, polycarbonate, polyphenylene sulfide, polyimide, polyaryletherketone, and polyetheretherketone.

[0026] Preferably, in the step of obtaining the material information of the prepreg to be prepared:

[0027] The reinforcing phase is made of at least one of the following materials: glass fiber, carbon fiber, basalt fiber, silicon carbide fiber, alumina fiber, aramid fiber, ultra-high molecular weight polyethylene fiber, and ultra-high molecular weight polypropylene fiber.

[0028] Preferably, the step of performing the grouting according to the grouting path includes:

[0029] The determined matrix phase, reinforcing phase, and suture are sequentially installed into the corresponding positions on the suture laying equipment;

[0030] Import the seam path into the seam laying equipment to perform seam laying.

[0031] Preferably, the step of impregnating the sewn product to obtain prepreg includes:

[0032] The product after stitching is placed upside down in a heated environment so that the matrix phase melts under heat and then impregnates into the reinforcing phase under gravity.

[0033] Compared with the prior art, this application has the following advantages:

[0034] 1. The prepreg preparation method proposed in this application can fully meet the stress requirements of the final composite product. The reinforcing phase fibers can be arranged in any direction, and can also be arranged in a non-linear direction to form a curved path, further expanding the application scenarios and breaking through the original limitation that the fibers can only be arranged in a straight line, thus having the advantage of strong designability.

[0035] 2. The amount of seam fiber used in this application is usually a few spindles, and the amount of stitch fiber used is also usually a few spindles. When switching varieties, only a few spindles need to be replaced, and the time usually does not exceed 10 minutes. In contrast, the traditional impregnation method usually requires the use of dozens or hundreds of spindles of raw materials. In addition, the switching time is at least 0.5 hours. Therefore, the preparation process of this application has the advantage of convenient variety switching.

[0036] 3. When preparing thermoplastic prepreg using the method of this application, the main loss is the product of the length from the stitch fiber placement area to the stitch position and the number of stitch cylinders. The number of cylinders is about tens to a few hundredths of the amount used in traditional thermoplastic prepreg, and the loss length is about a fraction of that of traditional thermoplastic prepreg.

[0037] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by means of embodiments thereof. Attached Figure Description

[0038] Figure 1A schematic flowchart of a method for preparing a thermoplastic prepreg according to an embodiment of this application is shown;

[0039] Figure 2 A schematic diagram of the structure of the spherical ultra-high molecular weight polyethylene felt in the first embodiment of this application is shown;

[0040] Figure 3 A schematic diagram of fiber orientation in the first embodiment of this application is shown;

[0041] Figure 4 A schematic diagram of the laying path in the first embodiment of this application is shown;

[0042] Figure 5 This invention provides a schematic diagram of the structure of the sheet material after seam laying in the first embodiment of this application.

[0043] Figure 6 A schematic diagram of the spherical top opening in the first embodiment of this application is shown;

[0044] Figure 7 A schematic diagram of the nylon 6 felt of the carbon fiber support structure in the second embodiment of this application is shown;

[0045] Figure 8 This invention provides another schematic diagram of the nylon 6 felt of the carbon fiber support structure in the second embodiment of this application.

[0046] Figure 9 This invention provides a schematic diagram of the pore positions in the felt of nylon 6 in the carbon fiber support structure of the second embodiment of this application.

[0047] Figure 10 A schematic diagram of the mounting base in the second embodiment of this application is shown;

[0048] Figure 11 A schematic diagram of the installation seat joint path in the second embodiment of this application is shown;

[0049] Figure 12 A schematic diagram of the carbon fiber support stitching path in the second embodiment of this application is shown;

[0050] Figure 13 A schematic diagram of the microstructure in the second embodiment of this application is shown. Detailed Implementation

[0051] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate several embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0053] In this document, unless otherwise stated, the term "tex" refers to the weight of a length of 1000m, where tex = g / L * 1000, and L is in meters; the term "g / m" refers to the weight of a length of 1000m. 2 "" refers to grams per square meter; "mm" refers to millimeters; "gsm" refers to a unit of weight, gsm = g / m². 2 The term "g" refers to grams; the term "m" refers to meters.

[0054] In this article, the term "all ranges" refers to both each specific range within a given range and combinations of subranges between given ranges. For example, the range 1–5 specifically includes 1, 2, 3, 4, and 5, and also includes subranges such as 2–5, 3–5, 2–3, 2–4, and 1–4.

[0055] <First Aspect>

[0056] like Figure 1 As shown, this application provides a method for preparing a thermoplastic prepreg, including the following steps S01 to S04:

[0057] S01: Obtain the material information of the prepreg to be prepared, the material information including at least the material of the matrix phase and the reinforcing phase, the material parameters of the reinforcing phase and the layup parameters;

[0058] It should be noted that, in some embodiments, the matrix phase material includes at least one of ultra-high molecular weight polyethylene, nylon, aramid, ultra-high molecular weight polypropylene, polycarbonate, polyphenylene sulfide, polyimide, polyaryletherketone, and polyetheretherketone, and the reinforcing phase material includes at least one of glass fiber, carbon fiber, basalt fiber, silicon carbide fiber, alumina fiber, aramid fiber, ultra-high molecular weight polyethylene fiber, and ultra-high molecular weight polypropylene fiber.

[0059] S02: Obtain the areal density of the matrix phase based on the materials of the matrix phase and the reinforcing phase, the material parameters of the reinforcing phase, and the layup parameters;

[0060] In some embodiments, in order to confirm the material parameters of the matrix phase, it is necessary to first obtain the material parameters of the reinforcing phase, such as the linear density and mass percentage of the reinforcing phase, and then calculate the areal density of the fiber layer after laying according to the following formula:

[0061] ρ1=ρ0 / d

[0062] Wherein, ρ1 represents the areal density of the fiber layer after laying, ρ0 represents the linear density of the reinforcing phase, and d represents the laying parameter, which refers to the spacing between two bundles of laid fibers during the laying process.

[0063] Next, the areal density of the matrix phase is calculated using the following formula:

[0064] ρ2=ρ1(1-w1) / w1

[0065] Wherein, ρ2 represents the areal density of the matrix phase, and w1 represents the mass percentage of the reinforcing phase in the prepreg.

[0066] It should be noted that, in the actual calculation of the stress process, the volume percentage is used as the calculation parameter. Since the reinforcing phase and the matrix phase are the same type of material and have the same density in this embodiment, the volume percentage and the mass percentage are also the same. Therefore, the conversion process between volume percentage and mass percentage is omitted in this embodiment, that is, the mass percentage and volume percentage of the reinforcing phase are equal.

[0067] S03: Obtain the stress requirements of the composite material, and set the fiber orientation of the reinforcing phase according to the stress requirements of the composite material;

[0068] In this step, only the final product, i.e., the composite material, has stress requirements. The prepreg is the material used to make the final product. The fiber orientation is determined according to the stress requirements of the final product. The fiber orientation is ultimately achieved through the prepreg. Based on the product design stress conditions, using the product CAD model and CAE analysis results, the selectable fiber orientation includes at least one of the following: circumferential, first preset angle, second preset angle, third preset angle, and fourth preset angle. This fully meets the stress requirements of the final composite product. The reinforcing phase fibers can be arranged in any direction, and can also be arranged in non-linear directions to form curved paths, further expanding the application scenarios and breaking through the original limitation that fibers can only be arranged in a straight line. For example, the first preset angle, second preset angle, third preset angle, and fourth preset angle can be 0°, 45°, -45°, and 90°, respectively.

[0069] In addition, in some embodiments, the fiber orientation can also be at other preset angles, and is not limited to the above four angles, in order to meet the needs of different fiber orientations.

[0070] In some embodiments, during the process of setting fiber orientation, the area where the fiber bends is located on the outside of the product, thereby further ensuring the mechanical properties of the product.

[0071] S04: Set the stitching path according to the fiber orientation of the reinforcing phase, perform stitching according to the stitching path, and impregnate the stitched product to obtain a prepreg.

[0072] It should be noted that in this step, after analyzing and obtaining information such as fiber orientation, thickness, and number of layers that meet the stress requirements of the composite material using CAE (Computer-Aided Engineering) methods, it is also necessary to use CAD (Computer-Aided Design) software to unfold the final product onto a plane while minimizing disruption to fiber continuity. After obtaining these two analysis results, the layup path is then calculated using CAM (Computer-Aided Manufacturing) software.

[0073] In addition, after obtaining the stitching path, the selected substrate, laid fibers, and stitching threads are sequentially installed to the corresponding positions on the stitching equipment; the stitching path is imported into the equipment and stitching is performed; cutting is then performed, and for irregularly shaped parts, cutting is carried out along the contour; and the stitched product is obtained.

[0074] Furthermore, in some embodiments, the purpose of impregnation is to mix the thermoplastic material in the substrate with the reinforcing material, requiring the use of heating equipment, and possibly pressure equipment or pressure equipment with heating function. The specific impregnation process is as follows: the product obtained after lamination is placed upside down in a heating environment. The thermoplastic resin material (matrix phase) melts upon heating and then impregnates downwards into the reinforcing fibers (reinforcing phase) under gravity. The temperature of the heating environment is set according to the softening point temperature characteristics of each thermoplastic material. For thermoplastic materials with poor flow properties, the external force of the pressure equipment can help the resin matrix material impregnate into the fiber interior. Heating followed by pressure can be used, or heating and pressure can be used simultaneously.

[0075] In summary, the above-described method for preparing thermoplastic prepregs has the following advantages:

[0076] 1. High designability: Based on the above prepreg preparation process and the fiber laying path designed by CAD, CAE and CAM, it can fully meet the stress requirements of the final composite product. The fibers can be arranged in any direction, and can also be arranged in non-linear directions to form curved paths, further expanding the application scenarios and breaking through the original limitation that the fibers can only be arranged in a straight direction.

[0077] 2. Convenient product switching: Based on the above prepreg preparation process, the amount of stitching fiber used is usually a few spindles, and the amount of sewing fiber used is also usually a few spindles. When switching products, only a few spindles need to be replaced, and the time usually does not exceed 10 minutes.

[0078] 3. Low raw material utilization: When using the process of this application to prepare thermoplastic prepreg, the main loss is the product of the length from the stitch fiber placement area to the stitch position and the number of stitch cylinders. The number of cylinders is about tens to hundreds of percent of the amount used in traditional thermoplastic prepreg, and the loss length is about a fraction of that of traditional thermoplastic prepreg.

[0079] 4. Variable shape, capable of forming irregular shapes such as holes and cuts: The fibers laid out using the preparation process of this application can be laid out according to the required net size of the sheet, directly obtaining a sheet consistent with the design size. Furthermore, for locations requiring openings or cuts, the original process could only achieve this by cutting fiber segments, which would damage the mechanical properties. When using the lay-up process of this application, the opening and cut effects can be directly obtained by optimizing the lay-up path, eliminating the fiber cutting process while ensuring the mechanical properties of the product.

[0080] 5. Variable thickness: When producing thermoplastic prepreg using the preparation process of this application, for application scenarios with variable thickness, when planning the stitching path, one or more layers of fibers can be added to the thickened area, or the spacing of the stitched fibers in that area can be adjusted. Reducing the spacing can increase the surface density and thicken the material, while increasing the spacing can reduce the surface density and thin the material, thereby achieving the effect of variable thickness and avoiding the need for additional material cutting in traditional processes.

[0081] Example 1

[0082] The applicant discovered that composite materials are typically obtained by laminating multiple layers of sheets and then molding them. Composite products come in various shapes, often with three-dimensional structures and curved surfaces, while the sheets used for lamination are all planar. Therefore, in practical applications, the sheet unfolding operation requires specialized technicians. This involves unfolding a thin-walled, three-dimensional shell into a planar shape; this thin-walled shell is typically of uniform wall thickness.

[0083] The unfolding process is similar to the sheet metal flattening process. To achieve flattening, the original continuous plane is typically disrupted by creating slits. After the sheet metal is bent and shaped, these slits are then reconnected using welding or other methods to form a whole. However, unlike traditional metal materials, the excellent mechanical properties of composite materials rely on continuous fibers. If the fibers are cut during the unfolding process, it will significantly affect the mechanical properties of the formed part. Therefore, minimizing or eliminating fiber cutting during unfolding has always been a key research focus and an important technical skill.

[0084] For spheres, flattening them without creating slits is mathematically proven impossible, yet spheres are a commonly used and practical structural form. Currently, when preparing spheres from continuous fiber reinforced composites, slits are used to flatten the sphere. Due to the symmetry of the sphere, avoiding cutting the fibers with slits is virtually impossible, significantly reducing the mechanical properties of the composite. Alternatively, when the curvature is small, the fibers can be twisted to form a sphere using the material's inherent deformability, which also affects mechanical properties and makes quality uncontrollable. Furthermore, automated fiber placement can effectively avoid the flattening problem and achieve ideal sphere formation, but this requires significant equipment investment and has high manufacturing costs, making it unsuitable for common applications.

[0085] Based on this, such as Figure 2 As shown, this embodiment uses a stitching method to prepare a thermoplastic prepreg suitable for spherical surfaces.

[0086] (1) Confirmation of material system: Ultra-high molecular weight polyethylene (UHMWPE) is used to reinforce ultra-high molecular weight polyethylene, wherein the reinforcing phase is ultra-high molecular weight polyethylene fiber and the matrix phase is ultra-high molecular weight polyethylene felt.

[0087] (2) Confirmation of material parameters: The prepared composite material has a Vf (fiber volume content) of about 65%, and the linear density of UHMWPE fiber is 133.3 tex (1200d). According to the width of the material, the fiber laying spacing is set to 2 mm (laying parameter) during the laying process. The surface density of the fiber layer after laying is calculated to be: 1000 / 2*133.3 / 1000=66.65g / ㎡. The surface density of the fiber is 66.65g / ㎡. Since the reinforcing phase and the matrix phase are both UHMWPE, the volume density is the same. Therefore, the mass percentage and the volume percentage are the same. According to the calculation based on the 35% content of ultra-high molecular weight polyethylene matrix, the theoretical surface density of the matrix phase is 66.65 / 65%*35%=35.88gsm. Therefore, 35gsm ultra-high molecular weight polyethylene felt is selected as the matrix phase.

[0088] (3) Confirmation of fiber orientation: Based on the requirements of the product design under stress conditions, and using the product CAD digital model and CAE analysis results, in this embodiment, the circumferential fiber arrangement provides the best mechanical properties, such as... Figure 3 As shown in the figure, the solid and dashed lines represent the outline of the sphere, and the dotted lines represent the designed fiber arrangement orientation. Traditional forming methods cannot achieve this effect without cutting the fibers.

[0089] (4) CAM stitching path design: Since the fiber arrangement is circumferential, equidistant spiral stitching can be used. A spherical effect can be achieved by utilizing the material's inherent deformability. The sphere radius is used as the maximum spiral radius, and the stitching spacing is 2mm. The stitching path is calculated as follows: Figure 4 As shown.

[0090] After the seams are laid, the final sheet material is obtained, such as... Figure 5 As shown.

[0091] Furthermore, in this embodiment, if the spherical top is considered to be an opening, the spiral in the center of the original paving path can be removed according to the diameter of the opening to achieve the effect of an opening, such as... Figure 6 As shown.

[0092] Furthermore, in this embodiment, to achieve the effect of adjusting the wall thickness, the pitch of the spiral can be adjusted. The magnitude of the pitch adjustment determines the rate of thickness change; the larger the pitch adjustment value in a single operation, the faster the thickness changes.

[0093] It should also be noted that, in this embodiment, the material loss involved in the entire preparation process is UHMWPE fiber and UHMWPE felt. Taking a spiral with a stitch outer diameter of 1000mm as an example, its weight is π.

[0094] *0.5m*0.5m*66.65=52.32g, corresponding to a fiber length of approximately 52.32g / 133.3tex=392.5m. This means the actual fiber length on the thermoplastic prepreg sheet is 392.5m. Fiber loss mainly occurs from the stitching fiber placement area to the stitching position, calculated as 10m. In this embodiment, the number of stitching fiber rolls is one, meaning the total loss is 10m of fiber. Therefore, the fiber loss rate is approximately 10 / (392.5+10)=2.48%. UHMWPE felt is a quasi-isotropic material; the cut-off scraps can generally be reused and therefore not included in the loss.

[0095] Using traditional processes, the continuous fiber effect seen in this embodiment cannot be achieved, and losses are significant. Without considering fiber orientation and spread, a traditional process to obtain a circle with a diameter of 1000mm requires direct cutting from a 1000mm*1000mm square, resulting in a material utilization rate of π*0.5m*0.5m / 1㎡ = 78.5%, or a loss rate of 21.5%. Considering factors such as spread and fiber orientation, the loss rate would only increase. For the matrix phase material, since similar materials and molding processes can be used, losses are also not considered.

[0096] In addition, it should be noted that the loss in this embodiment is the loss from fiber to usable sheet, while the path in the traditional process is fiber → intermediate → sheet. The above-mentioned 21.5% only calculates the loss from intermediate to sheet, and does not calculate the loss from fiber to intermediate. If the loss in this stage needs to be calculated, it will be included in the form of a product, thereby greatly increasing the loss rate. It can be seen that the preparation process of this application can greatly improve the utilization rate of the reinforcing material.

[0097] Example 2

[0098] This embodiment proposes a method for preparing a thermoplastic prepreg suitable for carbon fiber scaffolds, such as... Figure 7 and Figure 8 As shown, the specific steps are as follows:

[0099] (1) Confirmation of the material system: carbon fiber reinforced nylon 6 is used, wherein the reinforcing phase is carbon fiber and the matrix phase is nylon 6 felt.

[0100] (2) Confirmation of material parameters: The prepared composite material has a fiber content (Wf) of approximately 60%, using T700S grade 12K carbon fiber with a linear density of 800 tex. The thickness of a single layer of the material is set to 0.4 mm, and the fiber spacing is set to 2 mm during layup, corresponding to a fiber surface density of approximately 400 gsm per layer. The surface density of nylon 6 felt is approximately 400 / 0.6*0.4=266.7 gsm. Since this specification of material is unavailable, one layer of 200 gsm nylon 6 felt and one layer of 60 gsm nylon 6 felt are used as substitutes.

[0101] (3) Confirmation of fiber orientation: Based on the requirements of the product design under stress conditions, and using the product CAD model and CAE analysis results, in this embodiment, the fibers are laid out in a quasi-isotropic manner, i.e., alternating between 0° / +45° / -45° / 90°. Since this component is a deployable structure, the outline of the flattened sheet is obtained through a unfolding process.

[0102] (4) The design of the CAM stitching path involves products with numerous mounting holes. Using traditional processes, a hole-free workpiece is typically prepared first, and then the perforated product is obtained through subtractive processing. Firstly, this causes fiber breakage, requiring additional reinforcement at the perforation points to maintain performance. Secondly, subtractive processing itself is a waste of material. Finally, additional processing steps are needed, significantly increasing both cycle time and cost. In this embodiment, by leveraging the advantages of stitching technology and pre-reserving holes, the above three problems can be effectively avoided. Figure 9 and Figure 10As shown, taking the mounting base in a carbon fiber support as an example, the holes in the mounting base have stress requirements. In this local area, the more reasonable orientation of the fibers is to arrange them circumferentially around the holes, while in other positions they are still arranged according to the original design orientation. Based on this principle, the designed laying path is as follows: Figure 11 As shown, the stitching path includes four orientation directions: 0°, +45°, -45°, and 90°. Furthermore, to ensure mechanical properties, in this embodiment, the fiber bending area is located on the outer side of the product, further ensuring its mechanical performance. Figure 9 In the diagram, the inner green frame represents the actual usage area of ​​the product, the outer frame represents the seam boundary, and the area between the two frames represents the fiber bending area during the seam laying process. The fiber curve in this area is not the actual required orientation, and if it remains in the product, it will affect the performance.

[0103] Based on the above principles, the design drawing for the entire component's seam path is as follows: Figure 12 As shown in the figure, the shaded area represents the actual effective usage area of ​​the product.

[0104] In this embodiment, the thickness of the mounting base area is approximately twice that of the other areas, making it a variable-thickness component. To achieve a variable-thickness effect at the sheet end, the mounting base's stitching path can be repeatedly run at the mounting base location during the entire component stitching process to achieve the target thickness. Alternatively, the mounting base sheet can be stitched separately and used together during molding.

[0105] In a further embodiment of this invention, the entire component sheet needs to be overlapped after being wrapped during use. To ensure the overlap effect, some microstructures can be designed on the edge of the sheet, such as... Figure 13 As shown, a microstructure formed by a series of nested semicircles effectively improves the bonding effect at the seams.

[0106] In this embodiment, the loss of the matrix material is almost the same as that of traditional molding processes. Here, the utilization rate of the fiber material (reinforcing phase) is mainly calculated. Due to the addition of the fiber bend cutting area, the loss caused by this area will be additionally increased in this embodiment. Since the shapes of each product are different, the loss rate will be increased to 6-7% according to the data collected in actual use. If the traditional process is used, the loss rate for this embodiment is about 35%. It can be seen that the preparation process of this application can significantly improve the utilization rate of the reinforcing material.

[0107] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a thermoplastic prepreg, characterized in that, The method includes: Obtain the material information of the prepreg to be prepared, the material information including at least the material of the matrix phase and the reinforcing phase, the material parameters of the reinforcing phase, and the layup parameters; The areal density of the matrix phase is obtained based on the materials of the matrix phase and the reinforcing phase, the material parameters of the reinforcing phase, and the layup parameters. Obtain the stress requirements of the composite material, and set the fiber orientation of the reinforcing phase according to the stress requirements of the composite material; The stitching path is set according to the fiber orientation of the reinforcing phase, and stitching is performed according to the stitching path. The stitched product is then impregnated to obtain a prepreg. The step of obtaining the areal density of the matrix phase based on the materials of the matrix phase and the reinforcing phase, the material parameters of the reinforcing phase, and the layup parameters includes: The material parameters of the reinforcing phase include linear density and mass percentage. The areal density of the fiber layer after laying is calculated according to the following formula: in, This indicates the areal density of the fiber layer after it has been laid. This represents the linear density of the reinforcing phase. This indicates the layup parameters, which refer to the spacing between two bundles of laid fibers during the layup process; The areal density of the matrix phase is calculated using the following formula: in, This represents the areal density of the matrix phase. This indicates the mass percentage of the reinforcing phase in the prepreg.

2. The method for preparing the thermoplastic prepreg according to claim 1, characterized in that, In the step of obtaining the stress requirements of the composite material and setting the fiber orientation of the reinforcing phase according to the stress requirements of the composite material: The fiber orientation includes at least one of the following: circumferential, first preset angle, second preset angle, third preset angle, and fourth preset angle.

3. The method for preparing the thermoplastic prepreg according to claim 2, characterized in that, The steps of obtaining the stress requirements of the composite material and setting the fiber orientation of the reinforcing phase according to the stress requirements of the composite material include: In setting the fiber orientation, the area where the fiber bends is located on the outside of the product.

4. The method for preparing the thermoplastic prepreg according to claim 2, characterized in that, The step of setting the stitch path according to the fiber orientation of the reinforcing phase includes: If the fiber orientation is circumferential, then equidistant spiral stitching is used, and the pitch spacing is obtained according to the laying parameters.

5. The method for preparing the thermoplastic prepreg according to claim 1, characterized in that, In the step of obtaining the material information for the desired prepreg: The matrix phase material includes at least one of ultra-high molecular weight polyethylene, nylon, aramid, ultra-high molecular weight polypropylene, polycarbonate, polyphenylene sulfide, polyimide, polyaryletherketone, and polyetheretherketone.

6. The method for preparing the thermoplastic prepreg according to claim 1, characterized in that, In the step of obtaining the material information for the desired prepreg: The reinforcing phase is made of at least one of the following materials: glass fiber, carbon fiber, basalt fiber, silicon carbide fiber, alumina fiber, aramid fiber, ultra-high molecular weight polyethylene fiber, and ultra-high molecular weight polypropylene fiber.

7. The method for preparing the thermoplastic prepreg according to claim 1, characterized in that, The step of performing grouting according to the grouting path includes: The determined matrix phase, reinforcing phase, and suture are sequentially installed into the corresponding positions on the suture laying equipment; Import the seam path into the seam laying equipment to perform seam laying.

8. The method for preparing the thermoplastic prepreg according to claim 1, characterized in that, The step of impregnating the sewn product to obtain prepreg includes: The product after stitching is placed upside down in a heated environment so that the matrix phase melts under heat and then impregnates into the reinforcing phase under gravity.

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