Carbon fiber plate manufacturing method, carbon fiber plate and mobile phone middle frame assembly manufacturing method

Abstract

The invention relates to the technical field of machining, and discloses a carbon fiber plate manufacturing method, a carbon fiber plate and a mobile phone middle frame assembly manufacturing method.The method comprises the following steps that carbon fiber prepregs of different specifications are prepared according to the design requirements of an assembly; cutting the carbon fiber prepreg with the corresponding specification according to a preset laying layer design to obtain different laying layers; paving different paving layers on a paving layer jig according to a preset paving sequence to obtain a carbon fiber composite layer; the carbon fiber composite layer is transferred into a mold pressing mold, the mold pressing mold is transferred into mold pressing equipment for mold pressing, and a carbon fiber plate is obtained after demolding; and loading the carbon fiber plate onto a mechanical device, and machining the carbon fiber plate to form the mobile phone middle frame assembly. The mobile phone middle frame assembly can be produced by using the carbon fiber material, so that a metal material is replaced, the design requirement is met, the overall weight of a mobile phone is reduced, and the overall strength of the mobile phone is improved.

Description

Technical Field

[0001] The present invention relates to the field of mechanical processing technology, and in particular to a method for manufacturing a carbon fiber plate, a carbon fiber plate and a mobile phone middle frame assembly. Background Art

[0002] The middle frame of a mobile phone is a frame located between the front panel and the back cover of the phone. It carries various components inside the phone, such as the battery, motherboard, camera, cables, various sensors, microphone, earpiece, etc. It is the "skeleton" on which these components can be fixed and installed.

[0003] Currently, the internal middle frame components of most mobile phone manufacturers and mobile phone models are made of aluminum alloy. In the high-end market or specific scenarios, titanium alloy is also used as the material of the mobile phone middle frame. However, whether it is aluminum alloy or titanium alloy, there are significant problems as the material of the mobile phone middle frame component.

[0004] For aluminum alloys, although aluminum alloys have certain corrosion resistance, oxidation or corrosion may still occur on the surface of aluminum alloys under certain environments (such as moisture, salt spray, etc.). In order to enhance its corrosion resistance, it is usually necessary to anodize or coat the surface of aluminum alloys. However, these treatment processes increase production costs, and wear or peeling may still occur after long-term use, affecting the appearance and durability of the mobile phone. In addition, although aluminum alloys are lightweight, their strength is relatively low. In order to meet the strength requirements of the mobile phone middle frame, it is usually necessary to increase the thickness of the material or use high-strength aluminum alloys. This will lead to an increase in the weight of the mobile phone, which conflicts with consumers' demand for thin and light mobile phones. At the same time, aluminum alloys are prone to deformation or fracture when subjected to strong impact, affecting the structural integrity of the mobile phone.

[0005] Titanium alloys have unique advantages such as high strength, low density, excellent corrosion resistance and biocompatibility. However, although the density of titanium alloys is lower than that of stainless steel, its weight advantage is not obvious compared with aluminum alloys. For example, the density of titanium alloys is about 4.5g / cm 3 , while the density of aluminum alloy is only 2.7g / cm 3 . For mobile phone designs that pursue extreme lightweight, titanium alloys cannot provide significant weight reduction effects. Instead, they may increase material thickness due to strength requirements, resulting in increased weight. In addition, due to the high hardness of titanium alloys, the tool is easily worn during processing, increasing processing difficulty and cost. At the same time, the forming process of titanium alloys is complicated and requires the use of high-precision equipment (such as multi-axis CNC machine tools), which further raises the production threshold and makes its processing efficiency lower and the production cycle longer, making it difficult to meet the needs of large-scale mass production. Summary of the invention

[0006] In view of the deficiencies of the above-mentioned prior art, the technical problem to be solved by the present invention is: to provide a method for manufacturing a carbon fiber plate, a carbon fiber plate and a method for manufacturing a mobile phone middle frame assembly, and to utilize carbon fiber materials to produce a mobile phone middle frame assembly - Top frame, thereby replacing metal materials, thereby reducing the overall weight of the mobile phone while meeting the design requirements and improving the overall strength of the mobile phone.

[0007] In order to solve the above technical problems, a technical solution adopted by the present invention is: to provide a method for manufacturing a carbon fiber plate, the method comprising the following steps:

[0008] S1: Raw material preparation: Prepare various specifications of carbon fiber prepreg according to the design requirements of the components;

[0009] S2: Cutting and blanking: cutting the carbon fiber prepreg to obtain multiple layers;

[0010] S3: Prepreg laying: laying different layers on a laying device in a preset laying order to obtain a carbon fiber composite layer;

[0011] S4: Molding treatment: transferring the carbon fiber composite layer to a molding mold, transferring the molding mold to a molding equipment for molding, and obtaining a carbon fiber board after demolding.

[0012] Furthermore, the carbon fiber composite layer includes at least four carbon fiber prepreg plies of different specifications; the specifications include: a first specification having a tensile elastic modulus greater than or equal to 377 GPa and a FAW value of 15 to 25 g / m 2 The second specification is a prepreg with a tensile elastic modulus greater than or equal to 377GPa and a FAW value of 70 to 80g / m2; the third specification is a prepreg with a tensile strength greater than or equal to 4900MPa and a FAW value of 15 to 25g / m 2 Prepreg; the fourth specification is a tensile strength greater than or equal to 4900MPa, and a FAW value of 45 to 55g / m 2 of prepreg.

[0013] Furthermore, the carbon fiber composite layer includes a first ply, a sixth ply and an eighth ply, the ply angles of the first ply, the sixth ply and the eighth ply are first ply angles, and at least one ply whose ply angle is perpendicular to the first ply angle is laid between the first ply and the sixth ply, and between the sixth ply and the eighth ply.

[0014] Furthermore, the second to seventh plies are arranged between the first ply and the eighth ply, the second to seventh plies are intermediate plies, and the intermediate plies include at least three plies whose ply angles are different from the first ply angle.

[0015] Furthermore, the first ply and the eighth ply are cut from the carbon fiber prepreg of the first specification; the second ply and the seventh ply are cut from the carbon fiber prepreg of the second specification; the third ply, the fourth ply and the fifth ply are cut from the carbon fiber prepreg of the third specification; and the sixth ply is cut from the carbon fiber prepreg of the fourth specification.

[0016] Furthermore, before transferring the carbon fiber composite layer to the compression mold, a release layer is provided on the surface of the compression mold so that the carbon fiber composite layer does not contact the compression mold during the compression process.

[0017] Furthermore, transferring the molding die to the molding equipment for molding includes: transferring the molded die to a hot press after molding, and hot pressing the carbon fiber composite layer according to preset hot pressing parameters; transferring the hot pressing mold to a cold press table for pressure-maintaining cooling.

[0018] Furthermore, the preset hot pressing molding parameters include:

[0019] Transfer the compression mold to a hot press and preheat the compression mold for 100 to 140 seconds at a temperature of 90 to 110 degrees and a pressure of 0T;

[0020] Hot pressing the molding die for 280 to 320 seconds at a temperature of 100 to 120 degrees and a pressure of 1 to 3 T;

[0021] Using a mold temperature controller, the temperature of the compression mold is raised from 90 to 110 degrees to 110 to 130 degrees according to a first preset temperature curve, and the compression mold is hot-pressed for 220 to 260 seconds at a pressure of 3 to 5T;

[0022] Using a mold temperature controller, the temperature of the compression mold is raised from 110 to 130 degrees to 120 to 140 degrees according to a second preset temperature curve, and the compression mold is hot-pressed for 260 to 340 seconds at a pressure of 3 to 5T;

[0023] The temperature of the compression mold is lowered from 120 to 140 degrees to 50 to 70 degrees according to a third preset temperature curve by using a mold temperature controller, and the compression mold is hot pressed for 220 to 260 seconds at a pressure of 0.4 to 0.6T.

[0024] Another technical solution provided by the present invention is: a carbon fiber board, wherein the carbon fiber board is manufactured by any of the above-mentioned carbon fiber board manufacturing methods.

[0025] Another technical solution provided by the present invention is: a method for manufacturing a mobile phone middle frame assembly, comprising the carbon fiber board manufacturing method as described in any one of the above, and the mobile phone middle frame assembly manufacturing method further comprises:

[0026] S5: Mechanical processing: loading the carbon fiber plate onto a mechanical device and mechanically processing the carbon fiber plate to form a mobile phone middle frame assembly.

[0027] The carbon fiber plate and manufacturing method of the present invention have at least the following beneficial effects: 1. The overall manufacturing process is simple, the step of preparing prepreg is removed, and the finished carbon fiber prepreg is directly selected, which can not only ensure the stability of the quality of the raw materials, but also adapt to the design requirements of different products, and improve the design flexibility; 2. Strong corrosion resistance. The mobile phone middle frame assembly manufactured using carbon fiber prepreg has strong corrosion resistance compared with aluminum alloy materials; 3. High strength. The laying process is adopted in the manufacturing process, and the fiber laying angle of 0 degree / 90 degree symmetry is designed according to the different materials and thicknesses, so that the transverse and longitudinal strength of the product is balanced, and the stress is balanced during hot pressing, so as to ensure the minimum deformation after molding and the flatness can meet the requirements; 4. Lightweight. According to the present manufacturing method, the carbon fiber middle frame assembly manufactured using carbon fiber prepreg is much lighter than aluminum alloy materials and titanium alloy materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0029] Figure 1 It is a flowchart of the method for manufacturing a mobile phone middle frame assembly of the present invention;

[0030] Figure 2 It is a schematic diagram of the structure of the first ply, the third ply and the eighth ply according to an embodiment of the present invention;

[0031] Figure 3 It is a schematic structural diagram of the second layer and the sixth layer according to an embodiment of the present invention;

[0032] Figure 4 is a schematic structural diagram of a fourth layer according to an embodiment of the present invention;

[0033] Figure 5 is a schematic structural diagram of a fifth ply according to an embodiment of the present invention;

[0034] Figure 6 It is a schematic structural diagram of the seventh layer according to an embodiment of the present invention;

[0035] Figure 7 A schematic diagram of the paving sequence according to an embodiment of the present invention;

[0036] Figure 8 A schematic diagram of a layer laying jig structure according to an embodiment of the present invention;

[0037] Fig. 9 This is a schematic diagram of the structure of a carbon fiber plate according to an embodiment of the present invention;

[0038] Fig.10 A hot pressing process flow chart of an embodiment of the present invention;

[0039] Fig.11 The figure is a schematic structural diagram of a mobile phone middle frame assembly according to an embodiment of the present invention.

[0040] The meanings of the symbols in the accompanying drawings are:

[0041] Mobile phone middle frame assembly-10; first layer-11; second layer-12; third layer-13; fourth layer-14; fifth layer-15; sixth layer-16; seventh layer-17; eighth layer-18; carbon fiber plate-19; positioning hole-2; layer fixture-3; layer positioning pin-31. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings.

[0043] like Figures 1 to 11 As shown, the present invention provides a method for manufacturing a carbon fiber board, a carbon fiber board and a mobile phone middle frame assembly. The manufacturing method is aimed at processing the mobile phone middle frame assembly, and the material used is carbon fiber prepreg.

[0044] like Figure 1 As shown, the method for manufacturing a carbon fiber board of the present invention comprises the following steps:

[0045] S1: Raw material preparation: Prepare carbon fiber prepregs of various specifications according to the design requirements of the components.

[0046] In step S1, it is necessary to select a suitable carbon fiber prepreg according to the actual design requirements of the mobile phone middle frame. In this embodiment, taking the following design requirements as an example, if a mobile phone middle frame assembly needs to be designed, its strength must meet the following requirements: the overall part requires a tensile fracture strength of >3000N, and the overall part bending fracture strength is >60N. In order to meet the strength design, a carbon fiber prepreg with higher tensile strength (tensile strength greater than or equal to 4900Mpa) and a carbon fiber prepreg with higher tensile modulus (tensile modulus greater than or equal to 377Gpa) can be selected for mixing, so that the tensile strength and bending strength meet the requirements, and cost optimization can be taken into account at the same time. In addition, since the tensile strength of carbon fiber in the fiber direction is the strongest, according to the different materials and thicknesses, a symmetrical fiber ply angle of 0 degrees / 90 degrees is designed to balance the transverse and longitudinal strength of the product, and the stress is balanced during hot pressing to ensure the lowest deformation after molding and the flatness can meet the requirements.

[0047] In some embodiments, the carbon fiber composite layer includes at least four carbon fiber prepreg plies of different specifications; the specifications include: a first specification with a tensile elastic modulus greater than or equal to 377 GPa and a FAW value of 15 to 25 g / m 2 The second specification is a prepreg with a tensile elastic modulus greater than or equal to 377GPa and a FAW value of 70 to 80g / m2; the third specification is a prepreg with a tensile strength greater than or equal to 4900MPa and a FAW value of 15 to 25g / m 2 Prepreg; the fourth specification is a tensile strength greater than or equal to 4900MPa, and a FAW value of 45 to 55g / m 2 of prepreg.

[0048] Specifically, in step S1, the basic specifications of the carbon fiber prepreg have been determined according to the design requirements, that is, a mixture of carbon fiber prepregs with higher tensile strength (tensile strength greater than or equal to 4900Mpa) and carbon fiber prepregs with higher tensile modulus (tensile modulus greater than or equal to 377Gpa) is selected. In order to determine the final performance, processability and application of the carbon fiber board 19, an important parameter needs to be introduced, namely, the FAW value (Fiber Areal Weight) of the carbon fiber prepreg. The FAW value directly determines the lightweight potential, mechanical properties and manufacturing cost of the carbon fiber board 19. Therefore, in order to balance the lightweight degree, mechanical properties and manufacturing cost of the carbon fiber board 19, in this embodiment, the above specifications can be divided into four types: the first specification, the second specification, the third specification and the fourth specification. Among them, the first specification is that the tensile elastic modulus is greater than or equal to 377GPa, and the FAW value is 15-25g / m 2 The second specification is a prepreg with a tensile elastic modulus greater than or equal to 377GPa and a FAW value of 70 to 80g / m2; the third specification is a prepreg with a tensile strength greater than or equal to 4900MPa and a FAW value of 15 to 25g / m 2 Prepreg; the fourth specification is a tensile strength greater than or equal to 4900MPa, and a FAW value of 45 to 55g / m 2 of prepreg.

[0049] Furthermore, the above basic specifications can be refined according to the thickness distribution design of the mobile phone middle frame assembly 10, other parameters of the carbon fiber prepreg, and cost control in the actual production process. 3 ), RC value (resin content, in percentage), FAW (fiber surface density, in g / m 2 ), tow specifications, TG (glass transition temperature, in °C) and other parameters, the selected carbon fiber specifications are further divided. The first specification is modulus grade M40 (tensile elastic modulus equals 377GPa), FAW value is 20g / m2 , thickness is 0.025mm, density is 1.6g / m 3 , carbon fiber prepreg with a resin content of 40%; the second specification is a modulus grade of M40 (tensile elastic modulus equal to 377GPa), and a FAW value of 75g / m 2 , thickness is 0.08mm, density is 1.55g / m 3 , carbon fiber prepreg with a resin content of 38%; the third specification is a tensile strength of T700 (tensile strength equal to 4900MPa), and a FAW value of 20g / m 2 , thickness is 0.02mm, density is 1.55g / m 3 , carbon fiber prepreg with a resin content of 40%. The fourth specification is a tensile strength of T700 (tensile strength equal to 4900MPa), and a FAW value of 50g / m 2 , thickness 0.05mm, density 1.6g / m 3 , carbon fiber prepreg with a resin content of 40%. It should be noted that the selection of the above four specifications of carbon fiber prepreg is determined according to the product design requirements of this embodiment, and in the actual production process, the selected prepreg specifications can naturally be adaptively adjusted according to the actual design requirements and cost control.

[0050] like Figures 2 to 6 As shown, S2: cutting and blanking: cutting the carbon fiber prepreg to obtain multiple layers.

[0051] Specifically, after the specification of the carbon fiber prepreg is selected in step S1, the carbon fiber prepreg of the corresponding specification can be cut according to the preset ply design to form different plies. The preset ply design may include parameters such as the shape and thickness of each ply.

[0052] In some embodiments, the carbon fiber composite layer includes a first ply 11, a sixth ply 16 and an eighth ply 18, the ply angles of the first ply 11, the sixth ply 16 and the eighth ply 18 are first ply angles, and at least one ply whose ply angle is perpendicular to the first ply angle is laid between the first ply 11 and the sixth ply 16, and between the sixth ply 16 and the eighth ply 18.

[0053] Specifically, according to the above-mentioned 0 degree / 90 degree symmetrical fiber layup angle design, the carbon fiber composite layer (obtained by laying different plies in a preset layup order) may include a first ply 11, a sixth ply 16 and an eighth ply 18 with a layup angle of a first ply angle, and at least one ply with a layup angle perpendicular to the first ply angle is laid between the first ply 11 and the sixth ply 16, and between the sixth ply 16 and the eighth ply 18, and the first ply angle may be any angle, thereby forming a carbon fiber composite layer that meets the above-mentioned 0 degree / 90 degree symmetrical fiber layup angle design, so that the transverse and longitudinal strength of the product is balanced, and the stress is balanced during hot pressing, to ensure that the deformation after molding is minimized and the flatness can meet the requirements. Since the carbon fiber ply angles are generally -45 degrees, 0 degrees, 45 degrees, and 90 degrees, in this embodiment, the first ply 11, the sixth ply 16, and the eighth ply 18 can be set to 90±3 degrees or 0±3 degrees, then at least one ply with a ply angle of 0±3 degrees or 90±3 degrees is laid between the corresponding first ply 11 and the sixth ply 16, and the sixth ply 16 and the eighth ply 18, so that a carbon fiber composite layer that meets the above-mentioned 0 degree / 90 degree symmetrical fiber ply angle design can be formed, so that the transverse and longitudinal strength of the product is balanced, and the stress is balanced during hot pressing, ensuring the minimum deformation after molding and the flatness can meet the requirements. It should be noted that the ply angles mentioned in this scheme all represent the angle between the fiber extension direction of the carbon fiber ply and the length direction of the carbon fiber plate 19 or the mobile phone middle frame assembly 10.

[0054] In some embodiments, second to seventh plies are disposed between the first ply 11 and the eighth ply 18 , and the second to seventh plies are intermediate plies, and the intermediate plies include at least three plies having different ply angles from the first ply angle.

[0055] Specifically, in this embodiment, according to the above-mentioned design requirements, the final carbon fiber board 19 product can be formed by laying, molding and CNC processing eight layers, and in the actual production process, different numbers of layers can naturally be selected according to different design requirements. Among them, the eight layers can be represented by the first layer 11 to the eighth layer 18, the first layer 11, the sixth layer 16 and the eighth layer 18 are layers with a layer angle of 90±3 degrees or 0±3 degrees, and the remaining layers are layers with a layer angle of 0±3 degrees or 90±3 degrees. All eight layers are laid in a preset laying order to form a carbon fiber composite layer that meets the above-mentioned 0 degree / 90 degree symmetrical fiber layer angle design, so that the transverse and longitudinal strength of the product is balanced, and the stress is balanced during hot pressing, ensuring that the deformation after molding is minimal and the flatness can meet the requirements.

[0056] In some embodiments, the first ply 11 and the eighth ply 18 are cut from carbon fiber prepreg of the first specification; the second ply 12 and the seventh ply 17 are cut from carbon fiber prepreg of the second specification; the third ply 13, the fourth ply 14 and the fifth ply 15 are cut from carbon fiber prepreg of the third specification; the sixth ply 16 is cut from carbon fiber prepreg of the fourth specification.

[0057] Specifically, in this embodiment, the carbon fiber prepreg of corresponding specifications is cut according to the preset ply design to form different plies. Among them, the first ply 11 and the eighth ply 18 correspond to the carbon fiber prepreg of the first specification and are cut according to the carbon fiber prepreg of the first specification; the second ply 12 and the seventh ply 17 correspond to the carbon fiber prepreg of the second specification and are cut according to the carbon fiber prepreg of the second specification; the third ply 13, the fourth ply 14 and the fifth ply 15 correspond to the carbon fiber prepreg of the third specification and are cut according to the carbon fiber prepreg of the third specification; the sixth ply 16 corresponds to the carbon fiber prepreg of the fourth specification and is cut according to the carbon fiber prepreg of the fourth specification.

[0058] It is worth mentioning that the first ply 11 and the eighth ply 18 in this embodiment are the two outermost plies of the carbon fiber composite layer, and the shapes of the eight plies are cut according to the above-mentioned preset ply design. Figure 2-Figure 6 As shown, the first ply 11, the third ply 13 and the eighth ply 18 have the same shape, which is a rectangle with a plurality of positioning holes 2; the second ply 12 is a rectangle with a plurality of positioning holes 2 and a convex through-slot, and its size is the same as that of the rectangles of the first ply 11, the third ply 13 and the eighth ply 18; the fourth ply 14 is an elongated rectangle, and its length is the same as that of the rectangles of the first ply 11, the third ply 13 and the eighth ply 18; the fifth ply 15 is a rectangle with a right-angled trapezoid cut out at one vertex, and its length and width are both smaller than those of the rectangles of the first ply 11, the third ply 13 and the eighth ply 18; the shape and size of the sixth ply 16 are the same as those of the second ply 12; the seventh ply 17 is a rectangle with at least one positioning hole 2 and a convex through-slot, and a rectangle cut out from one side, and its size is smaller than that of the rectangles of the first ply 11, the third ply 13 and the eighth ply 18. It should be noted that the shapes and sizes of the first to eighth plies 11 to 18 are all in accordance with the preset ply design. In the actual production process, the shapes and sizes of different plies can be adjusted according to the actual ply design. In addition, a paving mark can be set on each ply according to the actual situation to facilitate positioning during paving.

[0059] like Figure 7As shown, S3: prepreg laying: laying different layers on a laying device according to a preset laying order to obtain a carbon fiber composite layer.

[0060] Specifically, the preset laying order in this embodiment is the serial number order of the above eight layers. According to the serial number order, different layers are laid on the laying jig 3 by manual laying, so as to obtain a carbon fiber composite layer.

[0061] In some embodiments, Figure 8 As shown, the ply positioning fixture 3 is provided with a ply positioning pin 31 , and the ply is provided with a positioning hole 2 or a positioning mark.

[0062] Specifically, the ply jig 3 in this embodiment is set according to the design requirements of the carbon fiber composite layer, and a ply positioning pin 31 is provided on its surface, which can correspond to the positioning holes 2 on different plies, so that during the plying process, the position of each ply is strictly aligned to avoid inter-layer misalignment caused by manual placement deviation, thereby avoiding material cutting errors or rework caused by ply misalignment, reducing waste generation, and also enabling workers to complete the plying by aligning the material with the ply positioning pin 31 without repeated measurement or adjustment, greatly shortening the single-layer plying time. It should be noted that in this embodiment, the fourth layer of the carbon fiber composite layer includes two fourth plies 14, and the seventh layer includes a seventh ply 17 and a ply cut from the second specification prepreg and having the same shape as the fourth ply 14. In addition, in the actual production process, the structure of the ply jig 3, the structure of the carbon fiber composite layer, and the shape and thickness of each ply can be adaptively adjusted according to the actual design requirements.

[0063] like Fig. 9 As shown, S4: molding treatment: transferring the carbon fiber composite layer to a molding mold, transferring the molding mold to a molding equipment for molding, and obtaining a carbon fiber plate 19 after demolding.

[0064] Specifically, after the layers are laid, the obtained carbon fiber composite layer needs to be molded and cured before it can form the carbon fiber board 19. The steps are: transferring the carbon fiber composite layer to a molding mold, transferring the molding mold to a molding equipment for molding, and obtaining the carbon fiber board 19 after demolding.

[0065] In some embodiments, before transferring the carbon fiber composite layer to the compression mold, a release layer may be provided on the surface of the compression mold so that the carbon fiber composite layer does not contact the compression mold during the compression process.

[0066] Specifically, according to the design requirements of the above-mentioned carbon fiber plate 19, it can be known that in this embodiment, the surface of the carbon fiber plate 19 is not a flat surface, so the inner surface of the mold used in the molding process, that is, the contact surface with the carbon fiber composite layer is also not a flat surface. In order to facilitate the demoulding of the carbon fiber plate 19 after the molding is completed, a release film can be laid on the upper and lower mold surfaces of the molding mold respectively, so as to avoid the resin in the carbon fiber plate 19 from adhering to the molding mold, so as to achieve the purpose of protecting the molding mold and facilitating demoulding. It should be noted that spraying or brushing a release agent on the contact surface between the molding mold and the carbon fiber composite layer can also achieve similar effects as mentioned above. Therefore, in the actual production process, it can be selected whether to use a release film or a release agent according to actual needs.

[0067] In some embodiments, transferring the molding die to a molding device for molding includes: transferring the molded die to a hot press, and hot pressing the carbon fiber composite layer according to preset hot pressing parameters; transferring the hot pressed molding die to a cold press table for pressure maintaining and cooling.

[0068] Specifically, the molding process in this embodiment includes hot pressing and pressure-maintaining cooling. During the hot pressing process, the carbon fiber composite layer will go through three stages, namely, heating and pressurizing, high-temperature curing, and cooling and shaping. The heating and pressurizing stage softens and flows the resin of the carbon fiber prepreg, infiltrates the fibers and discharges bubbles. The high-temperature curing stage cross-links and solidifies the resin to form a three-dimensional network structure, and the cooling and shaping stage changes the resin from a viscous flow state to a glassy state, thereby fixing the structure of the carbon fiber composite layer. After hot pressing, in order to avoid resin rebound, delamination warping or bubble cracking caused by direct pressure relief cooling, a pressure-maintaining cooling step is usually required to suppress residual stress and deformation, improve interlayer bonding and mechanical properties, and reduce internal defects.

[0069] In some embodiments, Fig.10 As shown, the preset hot pressing molding parameters include:

[0070] S41: transferring the compression mold to a hot press, and preheating the compression mold at a temperature of 90 to 110 degrees and a pressure of 0T for 100 to 140 seconds;

[0071] S42: hot pressing the molding die at a temperature of 100 to 120 degrees and a pressure of 1 to 3 T for 280 to 320 seconds;

[0072] S43: using a mold temperature controller, raising the temperature of the compression mold from 90 to 110 degrees to 110 to 130 degrees according to a first preset temperature curve, and hot pressing the compression mold for 220 to 260 seconds at a pressure of 3 to 5T;

[0073] S44: using a mold temperature controller, raising the temperature of the compression mold from 110 to 130 degrees to 120 to 140 degrees according to a second preset temperature curve, and hot pressing the compression mold for 260 to 340 seconds at a pressure of 3 to 5T;

[0074] S45: Using a mold temperature controller, the temperature of the compression mold is lowered from 120 to 140 degrees to 50 to 70 degrees according to a third preset temperature curve, and the compression mold is hot-pressed for 220 to 260 seconds at a pressure of 0.4 to 0.6T.

[0075] Specifically, the preset hot pressing molding parameters are the process parameters of the hot pressing process in this embodiment. At the same time, the five processes can be divided into four stages, namely, preheating stage, heating and pressurizing, high temperature curing and cooling and shaping. The step S41 is a preheating stage, in which the compression mold is transferred to a hot press, and the compression mold is preheated to 90-110 degrees (preferably 100 degrees) by a mold temperature controller under a pressure of 0T, and the preheating time is 100-140s (preferably 120s); the step S42 is a heating and pressurizing stage, in which the compression mold is hot-pressed for 280-320s (preferably 300s) at a temperature of 100-120 degrees (preferably 110 degrees) and a pressure of 1-3T (preferably 2T); the steps S43 and S44 are high-temperature curing stages, in which the temperature of the compression mold is firstly raised from 90-110 degrees (preferably 100 degrees) to 110-130 degrees (preferably 120 degrees) according to a first preset temperature curve by a mold temperature controller, and the compression mold is heated at a pressure of 3-5T (preferably 200 degrees) for 280-320s (preferably 300s). The molding die is hot pressed for 220 to 260 seconds (preferably 240 seconds), and then the temperature of the molding die is increased from 110 to 130 degrees (preferably 120 degrees) to 120 to 140 degrees (preferably 130 degrees) according to a second preset temperature curve by using a mold temperature controller, and the molding die is hot pressed for 260 to 340 seconds (preferably 300 seconds) under a pressure of 3 to 5T (preferably 4T); Step S45 is the cooling and shaping stage, during which the temperature of the molding die is cooled from 120 to 140 degrees (preferably 130 degrees) to 50 to 70 degrees (preferably 60 degrees) according to a third preset temperature curve by using a mold temperature controller, and the molding die is hot pressed for 220 to 260 seconds (preferably 240 seconds) under a pressure of 0.4 to 0.6T (preferably 0.5T). It should be noted that all of the above-mentioned preset hot pressing parameters are obtained based on the design requirements of the carbon fiber composite layer and the carbon fiber plate 19 in this embodiment, and in the actual production process, the hot pressing process parameters can be adaptively adjusted according to the design parameters of the actual workpiece.

[0076] The present invention further provides a carbon fiber plate, wherein the carbon fiber plate 19 is manufactured by any one of the above-mentioned carbon fiber plate manufacturing methods.

[0077] like Fig.11 As shown, the present invention also provides a method for manufacturing a mobile phone middle frame assembly, including the carbon fiber board manufacturing method as described in any one of the above, and the mobile phone middle frame assembly manufacturing method also includes:

[0078] S5: Mechanical processing: loading the carbon fiber plate 19 onto a mechanical device and mechanically processing the carbon fiber plate 19 to form a mobile phone middle frame assembly 10 .

[0079] Specifically, after the hot pressing and cold pressing processes, a carbon fiber plate 19 is obtained, and the carbon fiber plate 19 needs to be cut off to obtain the final mobile phone middle frame assembly 10. In this embodiment, the margin of the carbon fiber plate 19 is determined according to the design requirements. At the same time, since the carbon fiber plate 19 is a thin plate material, the method of cutting off the remaining margin can be applied to CNC milling or laser blanking, or first use CNC to mill out the edge margin, and then use laser blanking to cut other margins according to the shape of the mobile phone middle frame assembly 10. It is worth mentioning that if laser blanking is used, the above-mentioned positioning holes 2 or positioning marks for layer positioning can be used as positioning holes 2 or positioning marks for laser blanking. It should be noted that in the actual production process, the method of cutting off the margin also needs to be adaptively selected according to the actual shape, thickness and size of the semi-finished product. If the thickness of the semi-finished product is large, it is not suitable to use laser blanking to cut the margin.

[0080] The mobile phone middle frame assembly 10 manufactured by the above-mentioned carbon fiber plate manufacturing method has been verified to have all dimensions OK, and the product weight is more than 40% lower than that of the aluminum alloy material assembly and more than 60% lower than that of the titanium alloy material assembly.

[0081] Based on the above implementation, the carbon fiber board manufacturing method of the present invention has a simple process, removes the step of preparing prepreg, and directly selects the finished carbon fiber prepreg, which can not only ensure the stability of the quality of the raw materials, but also adapt to the design requirements of different products, and improve the design flexibility. The carbon fiber board 19 manufactured by the above manufacturing method has strong corrosion resistance compared with aluminum alloy materials; at the same time, the above carbon fiber board 19 adopts a layering process during the manufacturing process, and designs a 0 degree / 90 degree symmetrical fiber layering angle according to different materials and thicknesses, so that the product's transverse and longitudinal strength is balanced, and the stress is balanced during hot pressing, ensuring the minimum deformation after molding, and the flatness can meet the requirements; in addition, according to this manufacturing method, the carbon fiber middle frame assembly manufactured by using carbon fiber prepreg is much lighter than aluminum alloy materials and titanium alloy materials.

[0082] The above content only expresses the preferred embodiments of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A method for manufacturing a carbon fiber board, characterized in that: The method comprises the following steps: S1: Raw material preparation: Prepare various specifications of carbon fiber prepreg according to the design requirements of the components; S2: Cutting and blanking: cutting the carbon fiber prepreg to obtain multiple layers; S3: Prepreg laying: laying different layers on the laying device in sequence to obtain a carbon fiber composite layer; S4: Molding treatment: transferring the carbon fiber composite layer to a molding mold, transferring the molding mold to a molding equipment for molding, and obtaining a carbon fiber board after demolding.

2. The method for manufacturing a carbon fiber board according to claim 1, characterized in that: The carbon fiber composite layer includes at least four carbon fiber prepreg plies of different specifications; the specifications include: the first specification is that the tensile elastic modulus is greater than or equal to 377GPa, and the FAW value is 15-25g / m 2 The second specification is a prepreg with a tensile elastic modulus greater than or equal to 377GPa and a FAW value of 70 to 80g / m2; the third specification is a prepreg with a tensile strength greater than or equal to 4900MPa and a FAW value of 15 to 25g / m 2 Prepreg; the fourth specification is a tensile strength greater than or equal to 4900MPa, and a FAW value of 45 to 55g / m 2 of prepreg.

3. The method for manufacturing a carbon fiber board according to claim 2, characterized in that: The carbon fiber composite layer includes a first ply, a sixth ply and an eighth ply, wherein the ply angles of the first ply, the sixth ply and the eighth ply are first ply angles, and at least one ply whose ply angle is perpendicular to the first ply angle is laid between the first ply and the sixth ply, and between the sixth ply and the eighth ply.

4. The method for manufacturing a carbon fiber board according to claim 3, characterized in that: The second to seventh plies are arranged between the first ply and the eighth ply, the second to seventh plies are intermediate plies, and the intermediate plies include at least three plies with ply angles different from the first ply angle.

5. The method for manufacturing a carbon fiber board according to claim 4, characterized in that: The first ply and the eighth ply are both cut from the carbon fiber prepreg of the first specification; the second ply and the seventh ply are both cut from the carbon fiber prepreg of the second specification; the third ply, the fourth ply and the fifth ply are all cut from the carbon fiber prepreg of the third specification; the sixth ply is cut from the carbon fiber prepreg of the fourth specification.

6. The method for manufacturing a carbon fiber board according to claim 1, wherein: Before transferring the carbon fiber composite layer to the compression mold, a release layer is provided on the surface of the compression mold so that the carbon fiber composite layer does not contact the compression mold during the compression process.

7. The method for manufacturing a carbon fiber board according to claim 1, wherein: The transferring of the molding die to the molding equipment for molding includes: transferring the molded die to a hot press machine, and hot pressing the carbon fiber composite layer according to preset hot pressing parameters; and transferring the hot pressed mold to a cold press table for pressure-maintaining cooling.

8. The method for manufacturing a carbon fiber board according to claim 7, wherein: The preset hot pressing molding parameters include: Transfer the compression mold to a hot press and preheat the compression mold for 100 to 140 seconds at a temperature of 90 to 110 degrees and a pressure of 0T; Hot pressing the molding die for 280 to 320 seconds at a temperature of 100 to 120 degrees and a pressure of 1 to 3 T; Using a mold temperature controller, the temperature of the compression mold is raised from 90 to 110 degrees to 110 to 130 degrees according to a first preset temperature curve, and the compression mold is hot-pressed for 220 to 260 seconds at a pressure of 3 to 5T; Using a mold temperature controller, the temperature of the compression mold is raised from 110 to 130 degrees to 120 to 140 degrees according to a second preset temperature curve, and the compression mold is hot-pressed for 260 to 340 seconds at a pressure of 3 to 5T; The temperature of the compression mold is lowered from 120 to 140 degrees to 50 to 70 degrees according to a third preset temperature curve by using a mold temperature controller, and the compression mold is hot pressed for 220 to 260 seconds at a pressure of 0.4 to 0.6T.

9. A carbon fiber board, characterized in that: The carbon fiber board is manufactured by the carbon fiber board manufacturing method according to any one of claims 1 to 8.

10. A method for manufacturing a mobile phone middle frame assembly, characterized in that: The method for manufacturing a carbon fiber board according to any one of claims 1 to 8, wherein the method for manufacturing a mobile phone middle frame assembly further comprises: S5: Mechanical processing: loading the carbon fiber plate onto a mechanical device and mechanically processing the carbon fiber plate to form a mobile phone middle frame assembly.

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