Middle frame, preparation method of middle frame and electronic equipment

Abstract

The invention provides a middle frame, a preparation method of the middle frame and electronic equipment, relates to the technical field of electronic equipment, and aims to solve the problem that the middle frame cannot effectively give consideration to structural performance and lightening and thinning. The middle frame provided by the invention comprises a side frame and a middle plate, wherein the middle plate is provided with a battery placement part; the middle frame comprises a base material area and a composite area, the base material area is made of a base material, and the composite area is made of a doped base material; the base material area at least covers the outer side face of the middle frame, the composite area at least covers the battery placement part, the base material area and the composite area are metallurgically bonded, and the middle frame is of an integrally formed structure. According to the middle frame provided by the invention, the base material area and the composite area of the middle frame are made of different materials, so that the base material area and the composite area have different structural performance, the structural performance of the whole middle frame can be optimized, metallurgical bonding between interfaces of the base material area and the composite area is facilitated, integrated manufacturing of the middle frame can be realized, and the production efficiency is improved. The composite area has good structural performance, and the light and thin design of the whole composite area can be achieved.

Description

Technical Field

[0001] The present application relates to the technical field of electronic equipment, and in particular to a middle frame, a method for preparing the middle frame, and an electronic device. Background Art

[0002] In current mobile phones, the middle frame is usually used as the main structure of the mobile phone. The middle frame can provide effective structural strength for the mobile phone. When the mobile phone is dropped or subjected to external force, it can prevent the mobile phone from deforming and other adverse conditions. In some current mobile phones, the middle frame mainly includes a frame and a middle plate located within the outline surrounded by the frame. The frame can effectively protect the edge of the display screen, thereby improving the safety of the display screen. In addition, the outer side of the frame can also serve as the appearance of the mobile phone, which can improve the integrity and user experience of the mobile phone. The middle plate can provide an effective installation position for components such as the display screen, battery, circuit board and back panel.

[0003] With the continuous development of mobile phones and the continuous improvement of user needs, the industry has higher requirements for the structural strength and thinness of the middle frame. Among them, the middle frame is generally processed in one piece with the same material, that is, the materials in different areas of the middle frame are basically the same. However, when the middle frame is relatively thin, its structural strength will be significantly reduced, which is not conducive to ensuring the structural strength and safety of the mobile phone. When the thickness of the middle frame is larger, its structural strength will increase, but the middle frame will cause a large encroachment on the space of the mobile phone, which is not conducive to the configuration of a larger capacity battery or more devices in the mobile phone. Therefore, how to effectively balance the structural strength and thinness of the middle frame has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] The present application provides a middle frame, a method for preparing the middle frame, and an electronic device that can effectively balance structural performance and thinness.

[0005] In the first aspect, the present application provides a middle frame, including a frame and a middle plate, the middle plate is located within the outline surrounded by the frame, and the middle plate has a battery placement portion. The middle frame includes a substrate area and a composite area, the substrate area is made of a substrate material, and the composite area is made of a doped substrate material. The substrate area at least covers the outer side of the middle frame, and the composite area at least covers the battery placement portion. Among them, the substrate area and the composite area are metallurgically combined, and the middle frame is an integrally formed structure. In the middle frame provided by the present application, the materials of the substrate area and the composite area of ​​the middle frame are different, so that the substrate area and the composite area have different structural properties, which is conducive to optimizing the structural properties of the entire middle frame. In addition, the substrate area is made of substrate material, the composite area is made of doped substrate material, and the substrate area and the composite area both contain substrate material, so that the interface between the substrate area and the composite area can be metallurgically combined, so that the integrated production of the middle frame can be realized, which is conducive to ensuring the integrity of the middle frame and the bonding strength between the substrate area and the composite area, thereby ensuring the structural stability of the middle frame. In addition, the composite area is made of doped substrate material, so that the composite area has better structural properties. Moreover, on the basis of ensuring effective structural strength, it is conducive to thinning the composite area, and can realize a lightweight design of the entire composite area or a part of the composite area.

[0006] In one example, the composite area covers the battery placement part, and the substrate area covers the area outside the battery placement part of the middle frame. The battery placement part can be thinned to reduce the space occupied by the battery placement part, which is beneficial for configuring a larger capacity battery in the battery placement part.

[0007] In one example, the substrate area covers the frame, and the composite area covers the middle plate. After the composite area covers the middle plate, it is beneficial to achieve the thinning of the entire middle plate, which can effectively improve the overall structural performance and thinness of the middle frame.

[0008] In one example, the composite area includes a first composite area and a second composite area, and the first composite area covers the battery placement portion. The doping ratio of the first composite area is greater than the doping ratio of the second composite area, and the first composite area and the second composite area are metallurgically bonded. The first composite area and the second composite area have different material components, so that the first composite area and the second composite area have different structural properties, thereby further optimizing the structural performance of the entire middle frame.

[0009] In one example, the elastic modulus of the composite region may be greater than the elastic modulus of the substrate region. Alternatively, the elastic modulus of the first composite region is greater than the elastic modulus of the second composite region.

[0010] In the specific setting, the elastic modulus of the substrate area is greater than or equal to 68GPa and less than or equal to 72GPa. The elastic modulus of the first composite area is greater than or equal to 110GPa and less than or equal to 145GPa. The elastic modulus of the second composite area is greater than or equal to 85GPa and less than 110GPa. Through the effective regulation of the elastic modulus, the middle frame can effectively balance the elastic modulus and ductility.

[0011] In a specific configuration, the substrate material is aluminum alloy. The doping material of the composite area includes at least one of silicon carbide, aluminum oxide, boron carbide, titanium diboride, graphene, carbon nanotubes, graphite, and diamond. The aluminum alloy material has a good anodizing effect and can provide good surface properties for the middle frame.

[0012] In the specific setting, the substrate material is an aluminum alloy with a mass fraction of aluminum greater than or equal to 88%. So that the substrate material has good low density, mechanical compatibility, chemical compatibility, thermal stability, high elastic modulus, high compression or tensile strength, good processing performance, low cost and other excellent characteristics. In addition, it can also effectively ensure the effect of anodizing and have good surface properties. The doping material in the composite area is silicon carbide powder greater than or equal to 0.5 microns and less than or equal to 1 micron, and the volume fraction of the doping material is less than or equal to 10%. Alternatively, the doping material in the composite area is silicon carbide powder greater than or equal to 3 microns and less than or equal to 20 microns, and the volume fraction of the doping material is greater than or equal to 8% and less than or equal to 25%. The elastic modulus of the composite material can be effectively improved, and it is not easy to deform when subjected to external force, so as to have better structural performance. In addition, the thermal conductivity of the composite material is also effectively improved, which is conducive to enhancing the heat dissipation effect of the middle frame.

[0013] In one example, the doping material in the first composite area and the second composite area is silicon carbide. The doping material in the first composite area is silicon carbide powder greater than or equal to 0.5 microns and less than or equal to 1 micron, and the volume fraction of the doping material is less than or equal to 10%. Alternatively, the doping material in the first composite area is silicon carbide powder greater than or equal to 3 microns and less than or equal to 20 microns, and the volume fraction of the doping material is greater than or equal to 15% and less than or equal to 50%. The doping material in the second composite area is silicon carbide powder greater than or equal to 0.5 microns and less than or equal to 1 micron, and the volume fraction of the doping material is less than 10%. Alternatively, the doping material in the second composite area is silicon carbide powder greater than or equal to 3 microns and less than or equal to 20 microns, and the volume fraction of the doping material is greater than or equal to 5% and less than or equal to 25%. The elastic modulus of the composite material can be effectively improved, and it is not easy to deform when subjected to external force, thereby having better structural performance. In addition, the thermal conductivity of the composite material is also effectively improved, which is conducive to enhancing the heat dissipation effect of the middle frame.

[0014] In one example, the middle frame further includes an anodized layer, which is located on the outer side of the frame. The anodized layer can effectively improve the chemical stability and other properties of the surface of the middle frame.

[0015] In one example, the substrate material is any one of titanium alloy, magnesium alloy and steel alloy. The doping material of the composite area includes at least one of silicon carbide, aluminum oxide, boron carbide, titanium diboride, graphene, carbon nanotubes, graphite and diamond. The material selection of the middle frame has good flexibility.

[0016] In a second aspect, the present application also provides a method for preparing a middle frame, wherein the middle frame includes a frame and a middle plate, the middle plate is located within the outline surrounded by the frame, and the middle plate has a battery placement portion. The method includes:

[0017] providing a cylindrical substrate;

[0018] Providing a cylindrical composite body;

[0019] Inserting the composite body into the cylinder of the base body, and making the composite body and the base body have an interference fit;

[0020] Metallurgically bonding the outer peripheral surface of the composite body to the inner wall of the substrate to form a cylindrical billet;

[0021] The blank is formed into a middle frame, the matrix forms a frame of the middle frame, and the composite forms a middle plate of the middle frame.

[0022] By adopting the above-mentioned preparation method, the integrated production of the middle frame can be realized, which is beneficial to ensure the integrity of the middle frame and the bonding strength between the substrate body and the composite body, thereby ensuring the structural stability of the middle frame.

[0023] In one example, providing a cylindrical composite body includes:

[0024] providing a first composite body in a cylindrical shape;

[0025] providing a second composite body in a cylindrical shape;

[0026] Inserting the first composite body into the cylinder of the second composite body, and making the first composite body and the second composite body have an interference fit;

[0027] The outer peripheral surface of the first composite body and the inner wall of the second composite body are metallurgically bonded to form a cylindrical composite body.

[0028] The first composite body and the second composite body are metallurgically bonded. The first composite body and the second composite body have different material components, so that the first composite body and the second composite body have different structural properties, thereby further optimizing the structural properties of the entire middle frame.

[0029] In one example, metallurgically bonding the outer circumferential surface of the composite body to the inner cylinder wall of the substrate includes: extruding the substrate using an extrusion process to metallurgically bond the outer circumferential surface of the composite body to the inner cylinder wall of the substrate.

[0030] In one example, metallurgically bonding the outer circumference of the first composite body to the inner wall of the second composite body to form a cylindrical composite body includes: extruding the second composite body using an extrusion process to metallurgically bond the outer circumference of the first composite body to the inner wall of the second composite body.

[0031] In one example, forming the blank into a middle frame includes:

[0032] The cylindrical blank is formed into a rectangular plate by forging process;

[0033] The rectangular plate body is formed into a middle frame by using a machining process.

[0034] In one example, the method further includes:

[0035] An anodizing process is used to prepare an oxide layer on the outer side of the middle frame.

[0036] On the third aspect, the present application also provides an electronic device, comprising a battery and the above-mentioned middle frame or the middle frame made by the above-mentioned preparation method. The battery is fixed in the battery placement portion of the middle frame. By applying the above-mentioned middle frame in electronic equipment, the structural performance of the electronic equipment can be effectively improved, and it is conducive to the thin and light design of the electronic equipment. In addition, the outer side of the frame can be made of materials such as aluminum alloy that are easy to carry out surface treatment, which is conducive to improving the surface performance, integrity and feel of the electronic equipment. In addition, the battery placement portion of the middle frame can be formed of a material with a higher elastic modulus, so it is conducive to providing a larger accommodation space for the battery, which is conducive to configuring a larger capacity battery in the electronic device, and can effectively improve the battery life of the electronic device.

[0037] In one example, the electronic device further includes a display screen and a back panel. The display screen is disposed on a first panel surface of the middle panel, and the back panel is disposed on a second panel surface of the middle panel. The first panel surface and the second panel surface are two opposite panels of the middle panel. The middle frame can provide an effective installation position for the display screen and the back panel, thereby fixing the electronic device into an integrated structure. In addition, the frame can also provide effective protection for the display screen, thereby improving the safety of the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of a three-dimensional structure of a middle frame provided in an embodiment of the present application;

[0039] Figure 2 A schematic diagram of a three-dimensional structure of another middle frame provided in an embodiment of the present application;

[0040] Figure 3 A schematic diagram of a planar structure of a middle frame provided in an embodiment of the present application;

[0041] Figure 4 for Figure 2 Schematic diagram of the cross-sectional structure along the AA direction;

[0042] Figure 5 A schematic diagram of a planar structure of another middle frame provided in an embodiment of the present application;

[0043] Figure 6 A flow chart of a method for preparing a middle frame provided in an embodiment of the present application;

[0044] Figure 7 A schematic structural diagram of a cylindrical substrate provided in an embodiment of the present application;

[0045] Figure 8 A schematic structural diagram of a cylindrical composite provided in an embodiment of the present application;

[0046] Fig. 9 A schematic diagram of the structure of a cylindrical blank provided in an embodiment of the present application;

[0047] Fig.10 A schematic diagram of a planar structure of a middle frame provided in an embodiment of the present application;

[0048] Fig.11 A schematic diagram of a planar structure of another middle frame provided in an embodiment of the present application;

[0049] Fig.12 A flow chart of another method for preparing a middle frame provided in an embodiment of the present application;

[0050] Fig.13 A schematic structural diagram of a cylindrical substrate provided in an embodiment of the present application;

[0051] Fig.14 A schematic structural diagram of a cylindrical first composite body provided in an embodiment of the present application;

[0052] Fig.15 A schematic structural diagram of a cylindrical second composite body provided in an embodiment of the present application;

[0053] Fig.16 A schematic structural diagram of a cylindrical composite provided in an embodiment of the present application;

[0054] Fig.17 A schematic diagram of the structure of a cylindrical blank provided in an embodiment of the present application;

[0055] Fig.18A schematic diagram of a planar structure of a middle frame provided in an embodiment of the present application;

[0056] Fig.19 A schematic diagram of the exploded structure of a mobile phone provided in an embodiment of the present application. DETAILED DESCRIPTION

[0057] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings.

[0058] In order to facilitate understanding of the middle frame provided in the embodiment of the present application, its application scenario is first introduced below.

[0059] The middle frame provided in the embodiment of the present application can be applied to electronic devices such as mobile phones, tablet computers, laptops, smart watches, and smart bracelets. The middle frame can be used as the main structure of the electronic device to ensure the mechanical strength and safety of the electronic device. In addition, the middle frame can also provide an effective installation location for electronic devices and structural parts in the electronic device. Alternatively, in some electronic devices, the heat generated by the electronic devices can also be effectively dissipated through the middle frame, thereby ensuring that the electronic device is within a normal temperature range.

[0060] like Figure 1 As shown, take the middle frame 10 of the mobile phone as an example. The middle frame 10 mainly includes a frame 11 and a middle plate 12 located within the outline surrounded by the frame 11. The outer side surface 111 of the frame 11 can be used as the appearance surface of the mobile phone, which can improve the integrity and user experience of the mobile phone. The middle plate 12 can provide an effective installation position for components such as the display screen, battery, circuit board and back plate in the mobile phone. With the continuous development of mobile phones and the continuous improvement of user needs, the industry has higher requirements for the structural strength and thinness of the middle frame 10. Among them, the middle frame 10 is generally processed in one piece using the same material, that is, the materials in different areas of the middle frame 10 are basically the same. This makes it impossible for the middle frame 10 to effectively balance its own structural strength and thinness.

[0061] Aluminum alloy material has good plasticity and toughness, and has the advantages of easy processing, engineering reliability and low price. In addition, aluminum alloy material can be used to prepare an oxide layer using an anodizing process, which is convenient for improving the surface performance of the frame 11. Therefore, a large number of middle frames 10 are prepared using aluminum alloy material.

[0062] In practical applications, the middle frame 10 is generally manufactured using an integrated manufacturing process. In simple terms, the aluminum alloy material is first formed into a rectangular plate-shaped blank by die-casting or casting, and then the blank is processed by a machining process such as a CNC machine tool (computer numerical control machine tools), thereby forming a middle frame 10 having a frame structure and a middle plate structure. The one-piece molded middle frame 10 has good structural stability and force strength, but the middle frame 10 made of the same material cannot effectively take into account both structural performance and lightness.

[0063] For example, the structural strength of the middle frame 10 made of aluminum alloy is low, and it is easy to deform when the mobile phone is subjected to a large external force, so the structural performance and safety of the mobile phone cannot be well guaranteed. In addition, when the thickness of the middle frame 10 is large, although the structural strength of the middle frame 10 is increased, the middle frame 10 will cause a large encroachment on the space of the mobile phone, which is not conducive to configuring a larger capacity battery or more devices in the mobile phone.

[0064] In addition, some middle frames 10 are made of stainless steel. Compared with aluminum alloy materials, stainless steel has better strength and can improve the structural performance of the middle frame 10. However, the middle frame 10 made of stainless steel is heavier, more difficult to process, and has higher material costs. In addition, stainless steel cannot obtain better surface properties through anodizing process, which is not conducive to wide application.

[0065] Some middle frames 10 are also made of two different materials to effectively take into account the excellent properties of different materials. For example, in some middle frames 10, the frame 11 is made of aluminum alloy material, and the middle plate 12 is made of stainless steel material. However, the frame 11 and the middle plate 12 are made of different materials. Therefore, when making them, it is necessary to form the frame 11 and the middle plate 12 separately, and then fix the formed middle plate 12 and the frame 11. However, this method cannot guarantee the integrity of the middle frame 10, and its structural strength cannot be effectively guaranteed. In addition, due to the different materials of the middle plate 12 and the frame 11, it is difficult to achieve effective welding between different materials. Alternatively, in some methods, the middle plate 12 and the frame 11 are fixedly connected by fasteners such as screws. However, the integrity of the middle frame 10 cannot be guaranteed, and better structural performance cannot be achieved.

[0066] To this end, the embodiment of the present application provides a middle frame 10 that can effectively balance structural strength and lightness.

[0067] In order to make the objectives, technical solutions and advantages of the present application more clear, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0068] like Figure 2 As shown, in an example provided in the present application, the middle frame 10 includes a frame 11 and a middle plate 12 , the middle plate 12 is located within the outline surrounded by the frame 11 , and the middle plate 12 has a battery placement portion 121 .

[0069] like Figure 2 and Figure 3 As shown, the middle frame 10 includes a substrate area 101 and a composite area 102, the substrate area 101 is made of a substrate material, and the composite area 102 is made of a doped substrate material. The substrate area 101 at least covers the outer side surface 111 of the middle frame 10, and the composite area 102 at least covers the battery placement portion 121. Among them, the substrate area 101 and the composite area 102 are metallurgically bonded, and the middle frame 10 is an integrally formed structure. Metallurgical bonding refers to the bonding formed by the mutual diffusion of atoms between the interfaces of two metals. This bonding is either a connection state formed under the action of temperature or pressure, or is formed under the combined action of temperature and pressure.

[0070] In the example provided in the present application, the substrate area 101 is formed by a substrate material, and the composite area 102 is formed by a composite material, that is, the middle frame 10 is formed by a substrate material and a composite material. In addition, the composite material is a doped substrate material, and both the substrate area 101 and the composite area 102 have substrate materials. Therefore, an effective metallurgical bond can be formed between the interface of the substrate area 101 and the composite area 102, so that the integrity of the middle frame 10 can be effectively guaranteed. During production, the middle frame 10 can be produced by an integrated molding process, so that the middle frame 10 is prepared into an integrated molding structure. In addition, the substrate area 101 covers the outer side surface 111 of the middle frame 10, so that the outer side surface 111 of the middle frame 10 has good surface properties. For example, when the composite material is an aluminum alloy, the outer side surface 111 of the middle frame 10 can be treated by an anodizing process to obtain better surface properties. It should be noted that the outer side surface 111 of the middle frame 10 refers to the outer side surface 111 of the middle frame 10 that is away from the middle plate 12. Alternatively, the outer side surface 111 of the middle frame 10 may also include the end surface of the frame 11. In summary, in some examples, when the middle frame 10 is used in electronic devices such as mobile phones, the exposed surfaces of the middle frame 10 can be understood as the outer side surface 111. In addition, after doping in the substrate material, the performance of the substrate material can be improved, and therefore, it is beneficial to increase the structural strength of the composite area 102. For example, in the example provided in the present application, the composite area 102 covers the battery placement portion 121. Compared with the substrate area 101, the composite area 102 has a higher elastic modulus and is not easily deformed when subjected to external force. Therefore, the overall structural strength of the middle frame 10 can be effectively improved. In addition, after the composite area 102 is thinned, its structural performance can still be effectively guaranteed, which is conducive to achieving the thinness of the middle frame 10.

[0071] In summary, in the middle frame 10 provided in the embodiment of the present application, the materials of the substrate area 101 and the composite area 102 of the middle frame 10 are different, so that the substrate area 101 and the composite area 102 have different structural properties, which is conducive to optimizing the structural performance of the entire middle frame 10. In addition, the substrate area 101 is made of substrate material, and the composite area 102 is made of doped substrate material. The substrate area 101 and the composite area 102 both contain substrate material, so that the interface between the substrate area 101 and the composite area 102 can achieve metallurgical bonding, thereby achieving integrated production of the middle frame 10, which is conducive to ensuring the integrity of the middle frame 10 and the bonding strength between the substrate area 101 and the composite area 102, thereby ensuring the structural stability of the middle frame 10. In addition, the composite area 102 is made of doped substrate material, so that the composite area 102 has good structural performance. Moreover, on the basis of ensuring effective structural strength, it is conducive to achieving thinning of the composite area 102, and can achieve a lightweight design of the entire composite area 102 or a part of the composite area 102.

[0072] For example, Figure 4 As shown, the battery placement portion 121 may be thinned, thereby reducing the space occupied by the battery placement portion 121 , which is beneficial for configuring a battery with a larger capacity in the battery placement portion 121 .

[0073] The composite material can specifically be a metal matrix composite (MMC). Metal matrix composite materials are generally composite materials that use metal or alloy as a matrix and artificially combine the matrix with one or more metal or non-metal reinforcements. Most of its reinforcement materials are inorganic non-metals, such as ceramics, carbon, graphite and boron, etc., and can also be metals. Among them, the reinforcement can be fibrous, whisker, granular, etc. The reinforcement reacts in the metal matrix to form self-reinforced composite materials, laminate metal matrix composite materials and other varieties. These metal matrix composite materials not only maintain the characteristics of the metal itself, but also have the comprehensive characteristics of composite materials. Through the optimized combination of different matrices and reinforcements, various high-performance composite materials can be obtained, which have various special properties and excellent comprehensive properties.

[0074] For example, in the examples provided in this application, the substrate material is specifically an aluminum alloy, wherein the mass fraction of aluminum in the aluminum alloy can be greater than or equal to 88%, so that the substrate material has good low density, mechanical compatibility, chemical compatibility, thermal stability, high elastic modulus, high compression or tensile strength, good processing performance, low cost and other excellent properties. In addition, it can also effectively ensure the effect of anodizing and have good surface properties.

[0075] The reinforcing material is specifically silicon carbide, that is, the composite material includes aluminum alloy and silicon carbide. The addition of silicon carbide can effectively improve the elastic modulus of the composite material, and it is not easy to deform when subjected to external force, so that it has better structural performance. In addition, it also effectively improves the thermal conductivity of the composite material, which is conducive to enhancing the heat dissipation effect of the middle frame 10.

[0076] In specific applications, the elastic modulus of the substrate region 101 and the composite region 102 may be various. For example, the elastic modulus of the substrate region 101 may be greater than or equal to 68 GPa and less than or equal to 72 GPa. The elastic modulus of the composite region 102 may be greater than or equal to 85 GPa and less than or equal to 145 GPa.

[0077] Wherein, when doping is performed, the physical form of the reinforcing material can be granular, powdery or fibrous. In addition, depending on the difference in the physical form of the reinforcing material, the volume fraction of the reinforcing material may also be different. For example, the reinforcing material may be silicon carbide powder greater than or equal to 0.5 microns and less than or equal to 1 micron, and the volume fraction of the reinforcing material is less than or equal to 10%. Alternatively, the reinforcing material may also be silicon carbide powder greater than or equal to 3 microns and less than or equal to 20 microns, and the volume fraction of the reinforcing material is greater than or equal to 8% and less than or equal to 25%. In the composite material, by adopting the silicon carbide powder of the above physical form and volume fraction, the composite material can have a higher elastic modulus, and can effectively take into account both processability and cost.

[0078] It should be noted that the substrate materials in the above-mentioned substrate area 101 and the composite area 102 refer to the same type of materials. It can be subdivided into the following two situations. One is that the substrate materials in the substrate area 101 and the composite area 102 are exactly the same. In this case, the doping materials in the composite area 102 only include reinforcing materials such as silicon carbide. The other is that the substrate materials in the substrate area 101 and the composite area 102 are not exactly the same, but the basic components are the same. In this case, the doping materials in the composite area 102 include both reinforcing materials such as silicon carbide and other materials.

[0079] For example, take the substrate material as an aluminum alloy. When the substrate materials in the substrate area 101 and the composite area 102 are exactly the same, the specific model of the aluminum alloy can be 6013, 3003, 6061, 6063, 7003, 7055, 2024, 7034, 5052 or 5083, etc., which are commonly used in the industry. When the substrate materials in the substrate area 101 and the composite area 102 are different, the specific model of the aluminum alloy in the substrate area 101 can be 6013, 3003, 6061, 6063 or 7003, etc., which are commonly used in the industry. The specific model of the aluminum alloy in the composite area 102 can be 7055, 2024, 7034, 5052 or 5083, etc., which are commonly used in the industry. That is, based on the aluminum alloy model of the substrate area 101, the aluminum alloy model used in the composite area 102 can be formed by doping aluminum or alloy materials. The specific type of aluminum alloy used in the substrate area 101 and the composite area 102 can be reasonably set according to actual needs, and this application does not impose any restrictions on this.

[0080] In addition, in composite materials, the physical form and volume fraction of the reinforcing material can be reasonably adjusted according to actual needs, which will not be elaborated here.

[0081] Of course, in other examples, the reinforcing material may also be at least one of silicon carbide, aluminum oxide, boron carbide, titanium diboride, graphene, carbon nanotubes, graphite, and diamond.

[0082] In addition, in other examples, the substrate material may specifically be titanium, titanium alloy, magnesium, magnesium alloy, steel or steel alloy, etc.

[0083] In practical applications, the specific materials of the base material and the reinforcement can be reasonably selected according to actual needs to obtain the required structural properties, which will not be elaborated here.

[0084] In specific configurations, the specific areas covered by the substrate region 101 and the composite region 102 may be various.

[0085] For example, Figure 2 and Figure 3As shown, in an example provided in the present application, the composite area 102 covers the battery placement part 121, and the substrate area 101 covers the area outside the battery placement part 121 of the middle frame 10. In general, the battery placement part 121 is an area that needs to be structurally strengthened or thinned. The composite area 102 only covers the battery placement part 121, which can effectively reduce the coverage area of ​​the composite area 102 and effectively reduce the material cost and processing cost of the middle frame 10. Specifically, compared with the substrate material, the material cost of the composite material is higher. Therefore, after the composite area 102 only covers the battery placement part 121, the coverage area of ​​the composite area 102 will be relatively small, which is conducive to reducing the use cost of the composite material. In addition, since the elastic modulus of the composite material is high and the processing difficulty of the composite material is high, therefore, after the composite area 102 only covers the battery placement part 121, the coverage area of ​​the composite area 102 will be relatively small, which is conducive to reducing the production cost of the middle frame 10. Among them, the composite material has a high elastic modulus, so the structural performance of the battery placement part 121 can be effectively enhanced. In addition, the thickness of the battery placement portion 121 can also be effectively reduced, which can provide a larger accommodation space for the battery. Alternatively, it can be understood that the battery placement portion 121 of the middle plate 12 is made of a composite material, and the other areas of the middle plate 12 are made of a substrate material, and the thickness of the battery placement portion 121 can be less than the average thickness of the middle plate 12. In addition, when the composite area 102 covers the battery placement portion 121, the overall elastic modulus and thermal conductivity of the middle frame 10 can also be effectively improved. For example, when all areas of the middle frame 10 are made of aluminum alloy material, the elastic modulus of the middle frame 10 is about 70GPa, and the thermal conductivity is less than 120W / mK. When a composite material is used, the elastic modulus of the middle frame 10 can be increased to more than 100GPa, which increases the elastic modulus of the entire middle frame 10 by 50%. The thermal conductivity can also be increased to more than 150W / mK.

[0086] Alternatively, please refer to Figure 2 and Figure 5 In another example provided in the present application, the substrate area 101 covers the frame 11, and the composite area 102 covers the middle plate 12. That is, the frame 11 is made of the substrate material as a whole, and the middle plate 12 is made of the composite material as a whole. The composite material has a high elastic modulus, so the middle plate 12 has good structural performance as a whole, so that the structural performance of the entire middle frame 10 can be effectively enhanced. In addition, the thickness of the entire middle plate 12 can also be effectively reduced, which is conducive to the realization of a lightweight design of the middle plate 12.

[0087] When manufacturing the center frame 10 , various specific processes may be used.

[0088] For example, Figure 6As shown, the embodiment of the present application also provides a method for preparing the middle frame 10, which may include the following steps:

[0089] Step S100: providing a cylindrical substrate.

[0090] Step S200: providing a cylindrical composite body.

[0091] Step S300: inserting the composite body into the cylinder of the base body, and making the composite body and the base body have an interference fit.

[0092] Step S400: metallurgically bonding the outer circumferential surface of the composite body to the inner wall of the substrate to form a cylindrical blank.

[0093] Step S500: forming the blank into a middle frame, so that the base forms a frame of the middle frame, and the composite forms a middle plate of the middle frame.

[0094] It should be noted that in practical applications, the materials of the substrate and the reinforcement can be various. In order to facilitate understanding of the technical solution of the present application, the following will be exemplified by taking the substrate material as aluminum alloy and the reinforcement as silicon carbide as an example.

[0095] See also Figure 7 , Figure 7 The cylindrical substrate after forming is shown. In step S100, the following steps may be specifically included:

[0096] The aluminum alloy material is melted and formed into a hollow cylindrical shape by extrusion or other processes. The specific model of the aluminum alloy material can be 6013, 3003, 6061, 6063 or 7003. It should be noted that in other preparation methods, the matrix can also be prepared by die casting, turning or other processes, which will not be described in detail here.

[0097] See also Figure 8 , Figure 8 The cylindrical composite body after forming is shown. In step S200, the following steps may be specifically included:

[0098] Submicron-grade (e.g., 0.5 micron to 1 micron) silicon carbide powder is used as a reinforcement. And the volume fraction of the reinforcement is about 5%. Alternatively, micron-grade (e.g., 3 micron to 20 micron) silicon carbide powder can also be used as a reinforcement. And the volume fraction of the reinforcement is about 21%.

[0099] Firstly, the silicon carbide powder is pretreated and surface modified to improve the uniform dispersion of silicon carbide in the aluminum alloy matrix and the wettability of the two.

[0100] Specifically, the silicon carbide powder can be subjected to pretreatments such as pickling, sensitization and activation in sequence, and then the silicon carbide powder is subjected to surface modification treatments such as chemical copper plating or nickel plating to obtain a reinforcement material.

[0101] The aluminum alloy powder and the above-mentioned reinforcement powder are uniformly mixed. The specific type of the aluminum alloy material can be 7055, 2024, 7034, 5052 or 5083, etc. The aluminum alloy powder can be in the form of particles less than or equal to 20 microns.

[0102] During the mixing process, the aluminum alloy powder and the reinforcement powder mentioned above can be uniformly mixed in a ball mill to achieve a non-segregation and non-agglomeration effect.

[0103] The mixed powder is cold pressed under a hydraulic press by a cold pressing process. During the cold pressing process, the pressure can be controlled at about 9 MPa, and the holding time can be about 40 minutes, thereby forming a cold pressed green body.

[0104] The cold pressed green body is processed by vacuum hot pressing sintering process. Specifically, the cold pressed composite green body can be placed in a hot pressing mold, and a graphite paper with a thickness of 0.5 mm is used as a lubricating medium to facilitate demoulding. The green body is hot pressed and sintered in a hot pressing furnace. When hot pressing and sintering, the temperature can be controlled at about 580 degrees Celsius, the pressure can be controlled at about 30 MPa, and the holding time can be controlled at about 60 minutes.

[0105] In addition, after hot pressing and sintering, the green body can be made into a cylindrical shape by milling or turning. The diameter of the cylindrical green body can be about 400 mm. The green body is finally prepared into a composite body.

[0106] It should be noted that the inner diameter of the substrate provided in the above step S100 may be about 400 mm. In practical applications, the inner diameter, outer diameter, length of the substrate and the outer diameter and length of the composite may be reasonably set according to actual needs.

[0107] In addition, in the above-mentioned step S200, the silicon carbide powder is sequentially subjected to pretreatments such as pickling, sensitization and activation. Then, the silicon carbide powder is subjected to surface modification treatments such as chemical copper plating or nickel plating to obtain the reinforcement material. Alternatively, the silicon carbide powder is subjected to high-temperature oxidation treatment in a high-temperature furnace to remove impurities adsorbed on the surface of the silicon carbide powder by high-temperature oxidation, and a layer of silicon oxide is formed on the surface of the silicon carbide powder to improve the wettability of the silicon carbide powder. In a specific implementation, when the silicon carbide powder is subjected to high-temperature oxidation treatment, the treatment temperature can be about 1000 degrees Celsius and the duration can be about 10 hours.

[0108] In addition, when the reinforcement obtained by high-temperature oxidation treatment is mixed with aluminum alloy powder, the reinforcement powder and the aluminum alloy powder can be preheated in a high-temperature furnace at 600 degrees Celsius for about 0.5 hours to desorb hydrogen, water, carbon monoxide, nitrogen and the like adsorbed on the surface of the reinforcement.

[0109] See also Fig. 9 , Fig. 9 The cylindrical blank is formed by combining a cylindrical composite body with a cylindrical base body. In step S300, the following steps may be specifically included:

[0110] The cylindrical composite body can be inserted into the cylinder of the cylindrical base body by using extrusion equipment such as a hydraulic press, so that the composite body and the base body are interference fit, thereby achieving a fixed connection between the composite body and the base body.

[0111] In step S400, it may specifically include: placing the interference-fitted matrix and the composite into an extruder, radially extruding the matrix at a reasonable extrusion ratio, so that the outer circumference of the composite is metallurgically bonded to the inner wall of the matrix, thereby forming a cylindrical billet.

[0112] It should be noted that, in order to realize mass production, the axial length of the blank can be relatively long, so the blank can be cut into uniform segments by a cutting process. Each segment of the blank can be made into one or more middle frames 10 .

[0113] See also Fig.10 , Fig.10 The formed middle frame 10 is shown. In step S500, the following steps may be specifically included:

[0114] The cylindrical blank is formed into a rectangular plate body by a forging process. The length of the plate body can be about 190 mm and the width can be about 80 mm. It is understandable that in practical applications, the size of the plate body can be determined according to the specific size of the middle frame 10, that is, the size of the plate body can be slightly larger than the size of the middle frame 10 to avoid undesirable situations such as structural defects. No further details are given here.

[0115] The plate body is subjected to solution treatment, quenching and aging treatment to obtain the plate body with the best performance. Specifically, the plate body can be subjected to solution treatment at a temperature of 450 degrees Celsius. The solution treatment time can be controlled to be about 4 hours. Then quenching is performed with cold water. After quenching, the plate body is subjected to artificial aging treatment at 150 degrees Celsius. The artificial aging treatment time can be about 15 hours.

[0116] Through the above-mentioned solid solution, quenching and aging treatment, the elastic modulus of the composite material in the plate body can be made to be about 102 GPa, the elongation is about 5.5%, and it has good structural performance.

[0117] The rectangular plate body is formed into the middle frame 10 by mechanical processing technology. Specifically, the plate body can be cut to form a plate body with a thickness of about 10 mm. Then, the plate body is processed by a machining process such as a computer numerical control machine tool to form the middle frame 10 having the frame 11 structure and the middle plate 12 structure.

[0118] Finally, the outer side surface of the frame 11 may be processed by an anodizing process to form a surface with an oxide layer.

[0119] In summary, in the above-mentioned preparation method, a blank with an integrated structure can be prepared by metallurgically combining the composite body and the matrix. The blank is processed and formed to realize the integrated preparation of the middle frame 10, so that the middle frame 10 is an integrated structure, which can effectively ensure the integrity of the middle frame 10, thereby improving the structural strength and stability of the middle frame 10.

[0120] In addition, it should be noted that when processing the integrated structure of the substrate and the composite, there are processes such as extrusion. It is difficult to ensure that the boundary contours of the substrate and the composite have high precision. Therefore, in the final structure of the middle frame 10, the substrate may not completely cover the entire frame 11, or the composite may not completely cover the entire middle plate 12. Alternatively, part of the frame 11 may be composed of the substrate, and another part of the frame may be composed of the composite. Part of the middle plate 12 may be composed of the composite, and another part of the frame may be composed of the substrate. However, this situation does not affect the purpose of the present invention.

[0121] That is, since the matrix is ​​wrapped around the outer peripheral surface of the composite body, at least the outer side surface of the middle frame 10 is formed by the matrix, which can make the frame 11 have better surface properties. In addition, at least part of the middle plate 12 is formed by the composite body, so the structural performance of the middle plate 12 can be effectively improved, and it is conducive to achieving the thinning of the middle plate 12.

[0122] In addition, the above-mentioned preparation process is only for illustrative purposes. In actual preparation, other processes or steps may be used to complete the production of the centering frame 10, which will not be described in detail here.

[0123] In addition, in other examples, the recombination region 102 may also include a plurality of different regions, wherein the doping materials of the different regions may be different, or the doping materials of the different regions may be the same, but with different doping ratios.

[0124] For example, Fig.11As shown, in another example provided in the present application, the middle frame 10 includes a substrate area 101 and a composite area 102, the composite area 102 includes a first composite area 1021 and a second composite area 1022, and the first composite area 1021 and the second composite area 1022 are metallurgically bonded. The first composite area 1021 and the second composite area 1022 have different material components, so that the first composite area 1021 and the second composite area 1022 have different structural properties, thereby further optimizing the structural properties of the entire middle frame 10.

[0125] The material components of the substrate area 101, the first composite area 1021, and the second composite area 1022 are different, so that the substrate area 101, the first composite area 1021, and the second composite area 1022 have different structural properties, which is conducive to optimizing the structural performance of the entire middle frame 10. In addition, the substrate area 101 is made of substrate material, and the first composite area 1021 and the second composite area 1022 are both made of doped substrate material. The substrate area 101, the first composite area 1021, and the second composite area 1022 all contain substrate materials, so that metallurgical bonding can be achieved between the interfaces of the substrate area 101, the first composite area 1021, and the second composite area 1022, so that the integrated production of the middle frame 10 can be achieved, which is conducive to ensuring the integrity of the middle frame 10. In addition, the first composite area 1021 and the second composite area 1022 are made of doped substrate materials, so that the first composite area 1021 and the second composite area 1022 have better structural properties. Moreover, on the basis of ensuring effective structural strength, it is beneficial to realize the thinning process of the first composite area 1021 and the second composite area 1022 , and can realize the lightweight design of the entire composite area 102 or a part of the composite area 102 .

[0126] In addition, the elastic modulus of the first composite region 1021 is greater than the elastic modulus of the second composite region 1022 , so that the first composite region 1021 can be further thinned, which is beneficial to reducing the average thickness of the entire composite region 102 .

[0127] In specific configuration, the first composite region 1021 may cover the battery placement portion 121 , and the battery placement portion 121 may be thinned, thereby increasing the space of the battery placement portion 121 , which is beneficial for configuring a battery with a larger capacity.

[0128] Specifically, in a specific configuration, the first composite area 1021 can cover the battery placement portion 121 of the middle plate 12, the second composite area 1022 can cover the area outside the battery placement portion 121 of the middle plate 12, and the substrate area 101 can cover the frame 11. This allows the frame 11, the battery placement portion 121, and the area outside the battery placement portion 121 of the middle plate 12 to have different structural properties. This can effectively balance the structural performance and thinness of the middle frame 10.

[0129] In specific applications, the elastic moduli of the substrate region 101 and the composite region 102 may be various.

[0130] For example, the elastic modulus of the substrate region 101 may be greater than or equal to 68 GPa and less than or equal to 72 GPa. The elastic modulus of the first composite region 1021 may be greater than or equal to 110 GPa and less than or equal to 145 GPa. The elastic modulus of the second composite region 1022 may be greater than or equal to 85 GPa and less than 110 GPa.

[0131] Wherein, when doping is performed, the physical form of the reinforcing material (or doping material) can be granular, powdery or fibrous. In addition, according to the difference in the physical form of the reinforcing material, the volume fraction of the reinforcing material may also be different. For example, in the first composite area 1021, the reinforcing material may be a silicon carbide powder greater than or equal to 0.5 microns and less than or equal to 1 micron, and the volume fraction of the reinforcing material is less than or equal to 10%. Alternatively, the reinforcing material may also be a silicon carbide powder greater than or equal to 3 microns and less than or equal to 20 microns, and the volume fraction of the reinforcing material is greater than or equal to 15% and less than or equal to 50%. In the second composite area 1022, the reinforcing material may be a silicon carbide powder greater than or equal to 0.5 microns and less than or equal to 1 micron, and the volume fraction of the reinforcing material is less than 10%. Alternatively, the reinforcing material may also be a silicon carbide powder greater than or equal to 3 microns and less than or equal to 20 microns, and the volume fraction of the reinforcing material is greater than or equal to 5% and less than or equal to 25%.

[0132] In specific applications, the specific components of the substrate materials in the substrate area 101, the first composite area 1021, and the second composite area 1022 can be the same or different. For example, the specific type of the aluminum alloy in the substrate area 101 can be 6013, 3003, 6061, 6063, or 7003, etc., which are commonly used in the industry. The specific type of the aluminum alloy in the first composite area 1021 and the second composite area 1022 can be 7055, 2024, 7034, 5052, or 5083, etc., which are commonly used in the industry. Among them, the specific type of the aluminum alloy used in the substrate area 101, the first composite area 1021, and the second composite area 1022 can be reasonably set according to actual needs, and this application does not limit this.

[0133] In addition, in the composite material of the first composite region 1021 and the second composite region 1022 , the physical form and volume fraction of the reinforcing material can be reasonably adjusted according to actual needs, which will not be elaborated herein.

[0134] Of course, in other examples, the reinforcing material may also be at least one of silicon carbide, aluminum oxide, boron carbide, titanium diboride, graphene, carbon nanotubes, graphite, and diamond.

[0135] In addition, in other examples, the substrate material may specifically be titanium, titanium alloy, magnesium, magnesium alloy, steel or steel alloy, etc.

[0136] In practical applications, the specific materials of the base material and the reinforcement can be reasonably selected according to actual needs to obtain the required structural properties, which will not be elaborated here.

[0137] In specific configuration, the specific areas covered by the substrate region 101 , the first composite region 1021 , and the second composite region 1022 may be various.

[0138] For example, Figure 2 and Fig.11 As shown, in an example provided in the present application, the first composite area 1021 covers the battery placement part 121, and the second composite area 1022 covers the area outside the battery placement part 121 of the middle plate 12. The substrate area 101 covers the frame 11. In general, the battery placement part 121 is an area that needs to be structurally strengthened or thinned. The first composite area 1021 only covers the battery placement part 121, which can effectively reduce the coverage area of ​​the first composite area 1021, and can effectively reduce the material cost and processing cost of the middle frame 10. Specifically, compared with the substrate material, the material cost of the composite material is higher. Therefore, after the first composite area 1021 only covers the battery placement part 121, the coverage area of ​​the first composite area 1021 will be relatively small, which is conducive to reducing the use cost of the composite material. In addition, due to the high elastic modulus of the composite material, the processing difficulty of the composite material is higher than that of the substrate material. Therefore, after the first composite area 1021 only covers the battery placement part 121, the coverage area of ​​the first composite area 1021 will be relatively small, which is conducive to reducing the production cost of the middle frame 10. In addition, when the first composite area 1021 covers the battery placement part 121 and the second composite area 1022 covers the area outside the battery placement part 121 of the middle plate 12, the overall elastic modulus and thermal conductivity of the middle frame 10 can also be effectively improved. For example, when the entire area of ​​the middle frame 10 is made of aluminum alloy material, the elastic modulus of the middle frame 10 is about 70GPa, and the thermal conductivity is less than 120W / mK. When a composite material is used, the elastic modulus of the middle frame 10 can be increased to more than 100GPa, which increases the elastic modulus of the entire middle frame 10 by 50%. The thermal conductivity can also be increased to more than 150W / mK. In addition, the thickness of the middle plate 12 can be reduced to about 0.15mm, and it still has good force performance. When the thickness of the battery placement part 121 is thinned, the capacity of the battery can be increased by about 100mA or more.

[0139] It is understandable that, in a specific configuration, the coverage area of ​​the first composite area 1021 may also be larger than the battery placement portion 121. The second composite area 1022 may also cover a portion of the frame 11. The substrate area 101 may also only cover the outer side surface 111 of the frame 11. No further details are given here.

[0140] When manufacturing the center frame 10 , various specific processes may be used.

[0141] For example, Fig.12 As shown, the embodiment of the present application also provides a method for preparing the middle frame 10, which may include the following steps:

[0142] Step S100: providing a cylindrical substrate.

[0143] Step S210: providing a first cylindrical composite body.

[0144] Step S220: providing a cylindrical second composite body.

[0145] Step S230: inserting the first composite body into the cylinder of the second composite body, and the first composite body and the second composite body are interference fit.

[0146] Step S240: metallurgically bonding the outer circumferential surface of the first composite body to the inner wall of the second composite body to form a cylindrical composite body.

[0147] Step S300: inserting the composite body into the cylinder of the base body, and making the composite body and the base body have an interference fit.

[0148] Step S400: metallurgically bonding the outer circumferential surface of the composite body to the inner wall of the substrate to form a cylindrical blank.

[0149] Step S500: forming the blank into a middle frame, making the base form the frame of the middle frame, making the first composite body form the battery placement part, and making the second composite body form the area outside the battery placement part of the middle plate.

[0150] It should be noted that in practical applications, the materials of the substrate and the reinforcement can be various. In order to facilitate understanding of the technical solution of the present application, the following will be exemplified by taking the substrate material as aluminum alloy and the reinforcement as silicon carbide as an example.

[0151] See also Fig.13 , Fig.13 The cylindrical substrate after forming is shown. In step S100, the following steps may be specifically included:

[0152] The aluminum alloy material is melted and formed into a hollow cylindrical shape by extrusion or other processes. The specific model of the aluminum alloy material can be 6013, 3003, 6061, 6063 or 7003. It should be noted that in other preparation methods, the matrix can also be prepared by die casting, turning or other processes, which will not be described in detail here.

[0153] See also Fig.14 , Fig.14 The first cylindrical composite body after forming is shown. In step S210, the following steps may be specifically included:

[0154] Submicron-grade (e.g., 0.5 micron to 1 micron) silicon carbide powder is used as a reinforcement. And the volume fraction of the reinforcement is about 5%. Alternatively, micron-grade (e.g., 3 micron to 20 micron) silicon carbide powder can also be used as a reinforcement. And the volume fraction of the reinforcement is about 40%.

[0155] Firstly, the silicon carbide powder is pretreated and surface modified to improve the uniform dispersion of silicon carbide in the aluminum alloy matrix and the wettability of the two.

[0156] Specifically, the silicon carbide powder can be subjected to pretreatments such as pickling, sensitization and activation in sequence, and then the silicon carbide powder is subjected to surface modification treatments such as chemical copper plating or nickel plating to obtain a reinforcement material.

[0157] The aluminum alloy powder and the above-mentioned reinforcement powder are uniformly mixed. The specific type of the aluminum alloy material can be 7055, 2024, 7034, 5052 or 5083, etc. The aluminum alloy powder can be in the form of particles less than or equal to 15 microns.

[0158] During the mixing process, the aluminum alloy powder and the reinforcement powder mentioned above can be uniformly mixed in a ball mill to achieve a non-segregation and non-agglomeration effect.

[0159] The mixed powder is cold pressed under a hydraulic press by a cold pressing process. During the cold pressing process, the pressure can be controlled at about 10 MPa, and the holding time can be about 30 minutes, thereby forming a cold pressed green body.

[0160] The cold pressed green body is processed by vacuum hot pressing sintering process. Specifically, the cold pressed composite green body can be placed in a hot pressing mold, and graphite paper with a thickness of about 0.6 mm is used as a lubricating medium to facilitate demoulding. The green body is hot pressed and sintered in a hot pressing furnace. During hot pressing and sintering, the temperature can be controlled at about 590 degrees Celsius, the pressure can be controlled at about 25 MPa, and the holding time can be controlled at about 40 minutes.

[0161] In addition, after hot pressing and sintering, the green body can be made into a cylindrical shape by milling or turning. The diameter of the cylindrical green body can be about 300 mm. The green body is finally prepared into a composite body.

[0162] In addition, in the above-mentioned step S210, the silicon carbide powder is sequentially subjected to pretreatments such as pickling, sensitization and activation. The silicon carbide powder is then subjected to surface modification treatments such as chemical copper plating or nickel plating to obtain a reinforcement material. Alternatively, the silicon carbide powder is subjected to high-temperature oxidation treatment in a high-temperature furnace to remove impurities adsorbed on the surface of the silicon carbide powder by high-temperature oxidation, and a layer of silicon oxide is formed on the surface of the silicon carbide powder to improve the wettability of the silicon carbide powder. In a specific implementation, when the silicon carbide powder is subjected to high-temperature oxidation treatment, the treatment temperature can be about 1000 degrees Celsius and the duration can be about 10 hours.

[0163] In addition, when the reinforcement obtained by high-temperature oxidation treatment is mixed with aluminum alloy powder, the reinforcement powder and the aluminum alloy powder can be preheated in a high-temperature furnace at 600 degrees Celsius for about 0.5 hours to desorb hydrogen, water, carbon monoxide, nitrogen and the like adsorbed on the surface of the reinforcement.

[0164] See also Fig.15 , Fig.15 The second cylindrical composite body after forming is shown. In step S220, the following steps may be specifically included:

[0165] Submicron-grade (e.g., 0.5 micron to 1 micron) silicon carbide powder is used as a reinforcement. And the volume fraction of the reinforcement is about 3%. Alternatively, micron-grade (e.g., 3 micron to 20 micron) silicon carbide powder can also be used as a reinforcement. And the volume fraction of the reinforcement is about 18%.

[0166] Firstly, the silicon carbide powder is pretreated and surface modified to improve the uniform dispersion of silicon carbide in the aluminum alloy matrix and the wettability of the two.

[0167] Specifically, the silicon carbide powder can be subjected to pretreatments such as pickling, sensitization and activation in sequence, and then the silicon carbide powder is subjected to surface modification treatments such as chemical copper plating or nickel plating to obtain a reinforcement material.

[0168] The aluminum alloy powder and the above-mentioned reinforcement powder are uniformly mixed. The specific type of the aluminum alloy material can be 7055, 2024, 7034, 5052 or 5083, etc. The aluminum alloy powder can be in the form of particles less than or equal to 15 microns.

[0169] During the mixing process, the aluminum alloy powder and the reinforcement powder mentioned above can be uniformly mixed in a ball mill to achieve a non-segregation and non-agglomeration effect.

[0170] The mixed powder is cold pressed under a hydraulic press by a cold pressing process. During the cold pressing process, the pressure can be controlled at about 10 MPa, and the holding time can be about 30 minutes, thereby forming a cold pressed green body.

[0171] The cold pressed green body is processed by vacuum hot pressing sintering process. Specifically, the cold pressed composite green body can be placed in a hot pressing mold, and graphite paper with a thickness of about 0.6 mm is used as a lubricating medium to facilitate demoulding. The green body is hot pressed and sintered in a hot pressing furnace. During hot pressing and sintering, the temperature can be controlled at about 590 degrees Celsius, the pressure can be controlled at about 25 MPa, and the holding time can be controlled at about 40 minutes.

[0172] In addition, in the above-mentioned step S220, the silicon carbide powder is sequentially subjected to pretreatments such as pickling, sensitization and activation. Then, the silicon carbide powder is subjected to surface modification treatments such as chemical copper plating or nickel plating to obtain the reinforcement material. Alternatively, the silicon carbide powder is subjected to high-temperature oxidation treatment in a high-temperature furnace to remove impurities adsorbed on the surface of the silicon carbide powder by high-temperature oxidation, and a layer of silicon oxide is formed on the surface of the silicon carbide powder to improve the wettability of the silicon carbide powder. In a specific implementation, when the silicon carbide powder is subjected to high-temperature oxidation treatment, the treatment temperature can be about 1000 degrees Celsius and the duration can be about 10 hours.

[0173] In addition, when the reinforcement obtained by high-temperature oxidation treatment is mixed with aluminum alloy powder, the reinforcement powder and the aluminum alloy powder can be preheated in a high-temperature furnace at 600 degrees Celsius for about 0.5 hours to desorb hydrogen, water, carbon monoxide, nitrogen and the like adsorbed on the surface of the reinforcement.

[0174] See also Fig.16 , Fig.16 The cylindrical composite body formed by combining the cylindrical first composite body with the cylindrical second composite body is shown. In step S230, the method may specifically include: using an extrusion device such as a hydraulic press to insert the cylindrical first composite body into the cylinder of the cylindrical second composite body, so that the first composite body and the second composite body are interference-fitted, thereby achieving a fixed connection between the first composite body and the second composite body.

[0175] In step S240, it may specifically include: placing the first composite body and the second composite body after interference fit into an extruder, radially extruding the second composite body under a reasonable extrusion ratio, so that the outer circumference of the first composite body is metallurgically bonded with the inner wall of the second composite body, thereby forming a cylindrical composite body.

[0176] In addition, after the first composite body and the second composite body are metallurgically combined, the outer peripheral surface of the second composite body can be processed by milling or turning to make the second composite body (or the entire composite body) into a cylindrical shape. The diameter of the cylindrical composite body can be about 350 mm.

[0177] See also Fig.17 , Fig.17 The cylindrical blank is formed by combining a cylindrical composite body with a cylindrical base body. In step S300, the following steps may be specifically included:

[0178] The cylindrical composite body can be inserted into the cylinder of the cylindrical base body by using extrusion equipment such as a hydraulic press, so that the composite body and the base body are interference fit, thereby achieving a fixed connection between the composite body and the base body.

[0179] It should be noted that the inner diameter of the substrate provided in the above step S100 may be about 350 mm. In practical applications, the inner diameter, outer diameter, length of the substrate and the outer diameter and length of the composite may be reasonably set according to actual needs.

[0180] In step S400, it may specifically include: placing the interference-fitted matrix and the composite into an extruder, radially extruding the matrix at a reasonable extrusion ratio, so that the outer circumference of the composite is metallurgically bonded to the inner wall of the matrix, thereby forming a cylindrical billet.

[0181] It should be noted that, in order to realize mass production, the axial length of the blank can be relatively long, so the blank can be cut into uniform segments by a cutting process. Each segment of the blank can be made into one or more middle frames 10 .

[0182] See also Fig.18 , Fig.18 The formed middle frame 10 is shown. In step S500, the following steps may be specifically included:

[0183] The cylindrical blank is formed into a rectangular plate body by a forging process. The length of the plate body can be about 190 mm and the width can be about 80 mm. It is understandable that in practical applications, the size of the plate body can be determined according to the specific size of the middle frame 10, that is, the size of the plate body can be slightly larger than the size of the middle frame 10 to avoid undesirable situations such as structural defects. No further details are given here.

[0184] The plate body is subjected to solution treatment, quenching and aging treatment to obtain the plate body with the best performance. Specifically, the plate body can be subjected to solution treatment at a temperature of 450 degrees Celsius. The solution treatment time can be controlled to be about 4 hours. Then quenching is performed with cold water. After quenching, the plate body is subjected to artificial aging treatment at 150 degrees Celsius. The artificial aging treatment time can be about 15 hours.

[0185] Through the above-mentioned solid solution, quenching and aging treatment, the elastic modulus of the first composite material can be about 145 GPa, and the elongation can be about 1.7%. The elastic modulus of the second composite material can be about 101 GPa, and the elongation can be about 6.1%, which has good structural performance.

[0186] The rectangular plate body is formed into the middle frame 10 by mechanical processing. Specifically, the plate body can be cut to form a plate body with a thickness of about 10 mm. Then, the plate body is processed by a machining process such as a computer numerical control machine tool to form the middle frame 10 having a frame structure and a middle plate structure.

[0187] Finally, the outer side surface of the frame 11 may be processed by an anodizing process to form a surface with an oxide layer.

[0188] In summary, in the above-mentioned preparation method, a blank with an integrated structure can be prepared by metallurgically combining the first composite body, the second composite body and the matrix. The blank is processed and formed to realize the integrated preparation of the middle frame 10, so that the middle frame 10 is an integrated structure, which can effectively ensure the integrity of the middle frame 10, thereby improving the structural strength and stability of the middle frame 10.

[0189] In addition, it should be noted that when processing the integrated structure of the substrate, the first composite and the second composite, there are processes such as extrusion. It is difficult to ensure that the boundary contours of the substrate, the first composite and the second composite have high precision. Therefore, in the final structure of the middle frame 10, the substrate may not completely cover the entire frame 11, or the first composite may not just cover the battery placement portion, and the second composite may not just cover the area outside the battery placement portion of the middle plate. Alternatively, part of the frame 11 may be composed of the substrate, and another part of the frame 11 may be composed of the second composite. Part of the middle plate 12 may be composed of the first composite and the second composite, and another part of the frame may be composed of the substrate. However, this situation does not affect the purpose of the present invention.

[0190] That is, since the matrix is ​​wrapped around the outer peripheral surface of the composite body, at least the outer side surface of the middle frame 10 is formed by the matrix, which can make the frame 11 have better surface properties. In addition, at least part of the middle plate 12 is formed by the composite body, so the structural performance of the middle plate 12 can be effectively improved, and it is conducive to achieving the thinning of the middle plate 12.

[0191] In addition, the above-mentioned preparation process is only for illustrative purposes. In actual preparation, other processes or steps may be used to complete the production of the centering frame 10, which will not be described in detail here.

[0192] It can be understood that in the above-mentioned preparation method, the reinforcement in the first composite zone and the second composite zone is silicon carbide as an example for exemplary description. However, in other examples, the reinforcement may also include at least one of silicon carbide, aluminum oxide, boron carbide, titanium diboride, graphene, carbon nanotubes, graphite, and diamond.

[0193] For example, when the reinforcement is a mixture of silicon carbide and graphene, the preparation method can be as follows:

[0194] The preparation of the substrate may include:

[0195] The aluminum alloy material is melted and formed into a hollow cylindrical shape by extrusion or other processes. The specific model of the aluminum alloy material can be 6013, 3003, 6061, 6063 or 7003. It should be noted that in other preparation methods, the matrix can also be prepared by die casting, turning or other processes, which will not be described in detail here.

[0196] When preparing the first complex, the following steps may be included:

[0197] Submicron-grade (such as 0.5 micron to 1 micron) silicon carbide powder and graphene are used as reinforcements in the first composite body, wherein the diameter of the silicon carbide powder can be about 90 nm, and the volume fraction can be about 20%, and the volume fraction of the graphene can be about 5%.

[0198] Firstly, the silicon carbide powder is pretreated and surface modified to improve the uniform dispersion of silicon carbide in the aluminum alloy matrix and the wettability of the two.

[0199] Specifically, the silicon carbide powder can be subjected to pretreatments such as pickling, sensitization and activation in sequence, and then the silicon carbide powder is subjected to surface modification treatments such as chemical copper plating or nickel plating to obtain a reinforcement material.

[0200] The aluminum alloy powder and the silicon carbide and graphene are uniformly mixed. The specific type of the aluminum alloy material can be 7055, 2024, 7034, 5052 or 5083, etc. The aluminum alloy powder can be in the form of particles less than or equal to 15 microns.

[0201] During mixing, the aluminum alloy powder can be uniformly mixed with the above-mentioned silicon carbide and graphene in a ball mill to achieve a non-segregation and non-agglomeration effect.

[0202] The mixed powder is cold pressed under a hydraulic press by a cold pressing process. During the cold pressing process, the pressure can be controlled at about 10 MPa, and the holding time can be about 30 minutes, thereby forming a cold pressed green body.

[0203] The cold pressed green body is processed by vacuum hot pressing sintering process. Specifically, the cold pressed composite green body can be placed in a hot pressing mold, and graphite paper with a thickness of about 0.6 mm is used as a lubricating medium to facilitate demoulding. The green body is hot pressed and sintered in a hot pressing furnace. During hot pressing and sintering, the temperature can be controlled at about 590 degrees Celsius, the pressure can be controlled at about 25 MPa, and the holding time can be controlled at about 40 minutes.

[0204] In addition, after hot pressing and sintering, the green body can be made into a cylindrical shape by milling or turning. The diameter of the cylindrical green body can be about 300 mm. The green body is finally prepared into a composite body.

[0205] When preparing the second complex, the following steps may be included:

[0206] Silicon carbide powder of about 10 microns is used as a reinforcement, and the volume fraction of the reinforcement is about 21%.

[0207] Firstly, the silicon carbide powder is pretreated and surface modified to improve the uniform dispersion of silicon carbide in the aluminum alloy matrix and the wettability of the two.

[0208] Specifically, the silicon carbide powder can be subjected to pretreatments such as pickling, sensitization and activation in sequence, and then the silicon carbide powder is subjected to surface modification treatments such as chemical copper plating or nickel plating to obtain a reinforcement material.

[0209] The aluminum alloy powder and the above-mentioned reinforcement powder are uniformly mixed. The specific type of the aluminum alloy material can be 7055, 2024, 7034, 5052 or 5083, etc. The aluminum alloy powder can be in the form of particles less than or equal to 15 microns.

[0210] During the mixing process, the aluminum alloy powder and the reinforcement powder mentioned above can be uniformly mixed in a ball mill to achieve a non-segregation and non-agglomeration effect.

[0211] The mixed powder is cold pressed under a hydraulic press by a cold pressing process. During the cold pressing process, the pressure can be controlled at about 10 MPa, and the holding time can be about 30 minutes, thereby forming a cold pressed green body.

[0212] The cold pressed green body is processed by vacuum hot pressing sintering process. Specifically, the cold pressed composite green body can be placed in a hot pressing mold, and graphite paper with a thickness of about 0.6 mm is used as a lubricating medium to facilitate demoulding. The green body is hot pressed and sintered in a hot pressing furnace. During hot pressing and sintering, the temperature can be controlled at about 590 degrees Celsius, the pressure can be controlled at about 25 MPa, and the holding time can be controlled at about 40 minutes.

[0213] The cylindrical first composite body is inserted into the cylinder of the cylindrical second composite body by using extrusion equipment such as a hydraulic press, so that the first composite body and the second composite body are interference-fitted, thereby achieving a fixed connection between the first composite body and the second composite body.

[0214] The first composite body and the second composite body after interference fit are placed in an extruder, and the second composite body is radially extruded under a reasonable extrusion ratio to metallurgically bond the outer circumference of the first composite body to the inner wall of the second composite body, thereby forming a cylindrical composite body.

[0215] In addition, after the first composite body and the second composite body are metallurgically combined, the outer peripheral surface of the second composite body can be processed by milling or turning to make the second composite body (or the entire composite body) into a cylindrical shape. The diameter of the cylindrical composite body can be about 370 mm.

[0216] The cylindrical composite body can be inserted into the cylinder of the cylindrical base body by using extrusion equipment such as a hydraulic press, so that the composite body and the base body are interference fit, thereby achieving a fixed connection between the composite body and the base body.

[0217] It should be noted that the inner diameter of the substrate prepared above can be about 370 mm. In practical applications, the inner diameter, outer diameter, length of the substrate and the outer diameter and length of the composite can be reasonably set according to actual needs.

[0218] The matrix and the composite body after interference fit are placed in an extruder, and the matrix is ​​radially extruded under a reasonable extrusion ratio so that the outer peripheral surface of the composite body is metallurgically bonded with the inner tube wall of the matrix, thereby forming a cylindrical billet.

[0219] It should be noted that, in order to realize mass production, the axial length of the blank can be relatively long, so the blank can be cut into uniform segments by a cutting process. Each segment of the blank can be made into one or more middle frames 10 .

[0220] The cylindrical blank is formed into a rectangular plate body by a forging process. The length of the plate body can be about 175 mm and the width can be about 74 mm. It is understandable that in practical applications, the size of the plate body can be determined according to the specific size of the middle frame 10, that is, the size of the plate body can be slightly larger than the size of the middle frame 10 to avoid undesirable situations such as structural defects. No further details are given here.

[0221] The plate body is subjected to solution treatment, quenching and aging treatment to obtain the plate body with the best performance. Specifically, the plate body can be subjected to solution treatment at a temperature of 450 degrees Celsius. The solution treatment time can be controlled to be about 4 hours. Then quenching is performed with cold water. After quenching, the plate body is subjected to artificial aging treatment at 150 degrees Celsius. The artificial aging treatment time can be about 15 hours.

[0222] Through the above-mentioned solid solution, quenching and aging treatment, the elastic modulus of the first composite material can be about 140 GPa, and the elongation can be about 1.5%. The elastic modulus of the second composite material can be about 104 GPa, and the elongation can be about 5.1%, which has good structural performance.

[0223] The rectangular plate body is formed into the middle frame 10 by mechanical processing technology. Specifically, the plate body can be cut to form a plate body with a thickness of about 7 mm. Then, the plate body is processed by a machining process such as a computer numerical control machine tool to form the middle frame 10 having a frame structure and a middle plate structure.

[0224] In practical applications, the middle frame 10 can be used in electronic devices such as mobile phones, tablet computers, laptops, smart watches, and smart bracelets.

[0225] like Fig.19 As shown, a mobile phone 20 is taken as an example. The mobile phone 20 may include a middle frame 10, a display screen 21, a back panel 22 and a battery 23. The battery 23 may be fixed to the battery placement portion 121 of the middle frame 10, so that the middle frame 10 can effectively protect the battery 23. When the mobile phone 20 is dropped or collided, the battery 23 can be fixed to the battery placement portion 121, thereby ensuring the safety of the battery 23 and the entire mobile phone 20. In addition, the battery 23 can also be thermally bonded to the battery placement portion 121. During the charging and discharging process of the battery 23, the heat generated by the battery 23 can be effectively conducted to the middle frame 10, thereby ensuring the heat dissipation performance of the battery 23.

[0226] The display screen 21 can be fixed on the first surface (the upper surface in the figure) of the middle plate 12, and the back plate 22 can be fixed on the second surface (the lower surface in the figure) of the middle plate 12. The edge of the display screen 21 can be wrapped within the outline of the frame 11, so that the frame 11 can effectively protect the display screen 21.

[0227] It is understandable that, in actual applications, the mobile phone 20 may also include components such as a circuit board, a camera, and a speaker, and the above components may be installed in the space enclosed by the middle frame 10 and the display screen 21, or in the space enclosed by the middle frame 10 and the back plate 22. In actual applications, the number and type of components included in the mobile phone 20 may be flexibly selected and adjusted according to actual needs, and this application will not elaborate on this.

[0228] By applying the above-mentioned middle frame 10 in the mobile phone 20, the structural performance of the mobile phone 20 can be effectively improved, and it is conducive to realizing the light and thin design of the mobile phone 20. In addition, the outer side surface 111 of the frame 11 of the middle frame 10 can be made of materials such as aluminum alloy that are easy to surface treat, which is conducive to improving the surface performance, integrity and feel of the mobile phone 20. In addition, the battery placement part 121 of the middle frame 10 can be formed of a material with a higher elastic modulus, so it is conducive to providing a larger accommodation space for the battery 23, which is conducive to configuring a larger capacity battery 23 in the mobile phone 20, and can effectively improve the battery life of the mobile phone 20.

[0229] It is understandable that, in actual applications, the middle frame 10 can also be used in electronic devices such as tablet computers, laptop computers, smart watches and smart bracelets, which will not be elaborated here.

[0230] In the various embodiments of the present application, unless otherwise specified or provided for in any logical conflict, the terms and / or descriptions between the different embodiments are consistent and may be referenced to each other, and the technical features in the different embodiments may be combined to form new embodiments according to their inherent logical relationships.

[0231] In this application, "multiple" means two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural.

[0232] It is understood that the various numbers involved in the embodiments of the present application are only for the convenience of description and are not used to limit the scope of the embodiments of the present application. The size of the sequence number of the above-mentioned processes does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic.

Claims

1. A middle frame, characterized in that: It comprises a frame and a middle plate, wherein the middle plate is located within the outline surrounded by the frame and has a battery placement portion; The middle frame includes a substrate area and a composite area, the substrate area is made of a substrate material, and the composite area is made of a doped substrate material; The substrate area at least covers the outer side surface of the middle frame, and the composite area at least covers the battery placement portion; Wherein, the substrate area and the composite area are metallurgically bonded, and the middle frame is an integrally formed structure.

2. The middle frame according to claim 1, characterized in that: The composite area covers the battery placement portion, and the substrate area covers an area of ​​the middle frame other than the battery placement portion.

3. The middle frame according to claim 1, characterized in that: The substrate area covers the frame, and the composite area covers the middle plate.

4. The middle frame according to claim 3, characterized in that: The composite area includes a first composite area and a second composite area, and the first composite area covers the battery placement part; The doping ratio of the first composite region is greater than the doping ratio of the second composite region, and the first composite region and the second composite region are metallurgically bonded.

5. The middle frame according to any one of claims 1 to 4, characterized in that: The thickness of the battery seating portion is smaller than the average thickness of the middle plate.

6. The middle frame according to any one of claims 1 to 5, characterized in that: The elastic modulus of the composite region is greater than the elastic modulus of the substrate region.

7. The middle frame according to claim 4, characterized in that: The elastic modulus of the first composite region is greater than the elastic modulus of the second composite region.

8. The middle frame according to claim 7, characterized in that: The elastic modulus of the substrate region is greater than or equal to 68 GPa and less than or equal to 72 GPa; The elastic modulus of the first composite region is greater than or equal to 110 GPa and less than or equal to 145 GPa; The elastic modulus of the second composite zone is greater than or equal to 85 GPa and less than 110 GPa.

9. The middle frame according to any one of claims 1 to 8, characterized in that: The substrate material is aluminum alloy; The doping material of the composite zone includes at least one of silicon carbide, aluminum oxide, boron carbide, titanium diboride, graphene, carbon nanotubes, graphite, and diamond.

10. The middle frame according to claim 9, characterized in that: The substrate material is an aluminum alloy with a mass fraction of aluminum greater than or equal to 88%; The doping material in the composite zone is silicon carbide powder greater than or equal to 0.5 microns and less than or equal to 1 micron, and the volume fraction of the doping material is less than or equal to 10%; or, The doping material in the recombination zone is silicon carbide powder greater than or equal to 3 micrometers and less than or equal to 20 micrometers, and the volume fraction of the doping material is greater than or equal to 8% and less than or equal to 25%.

11. The middle frame according to claim 4, characterized in that: The substrate material is an aluminum alloy with a mass fraction of aluminum greater than or equal to 88%, and the doping material in the first composite region and the second composite region is silicon carbide; The doping material in the first recombination zone is silicon carbide powder greater than or equal to 0.5 micrometers and less than or equal to 1 micrometer, and the volume fraction of the doping material is less than or equal to 10%; or, The doping material in the first recombination zone is silicon carbide powder greater than or equal to 3 microns and less than or equal to 20 microns, and the volume fraction of the doping material is greater than or equal to 15% and less than or equal to 50%; The doping material in the second recombination zone is silicon carbide powder greater than or equal to 0.5 micrometers and less than or equal to 1 micrometer, and the volume fraction of the doping material is less than 10%; or, The doping material in the second recombination zone is silicon carbide powder having a thickness greater than or equal to 3 micrometers and less than or equal to 20 micrometers, and a volume fraction of the doping material is greater than or equal to 5% and less than or equal to 25%.

12. The middle frame according to any one of claims 1 to 11, characterized in that: The middle frame further includes an anodized layer, and the anodized layer is located on the outer side of the frame.

13. The middle frame according to any one of claims 1 to 8, characterized in that: The substrate material is any one of titanium alloy, magnesium alloy and steel alloy; The doping material of the composite zone includes at least one of silicon carbide, aluminum oxide, boron carbide, titanium diboride, graphene, carbon nanotubes, graphite, and diamond.

14. A method for preparing a middle frame, wherein the middle frame comprises a frame and a middle plate, wherein the middle plate is located within the outline surrounded by the frame and has a battery placement portion, wherein: The method comprises: providing a cylindrical substrate; Providing a cylindrical composite body; Inserting the composite body into the cylinder of the base body, and the composite body and the base body are interference fit; Metallurgically bonding the outer circumferential surface of the composite body to the inner wall of the substrate to form a cylindrical blank; The blank is formed into a middle frame, the substrate forms a frame of the middle frame, and the composite forms a middle plate of the middle frame.

15. The method according to claim 14, characterized in that Providing the cylindrical composite body comprises: providing a first composite body in a cylindrical shape; providing a second composite body in a cylindrical shape; Inserting the first composite body into the cylinder of the second composite body, and making the first composite body and the second composite body have an interference fit; The outer peripheral surface of the first composite body and the inner wall of the second composite body are metallurgically bonded to form the cylindrical composite body.

16. The method according to claim 14 or 15, characterized in that The metallurgical bonding of the outer peripheral surface of the composite body with the inner cylinder wall of the substrate comprises: The matrix is ​​extruded by using an extrusion process, so that the outer peripheral surface of the composite body is metallurgically bonded with the inner cylinder wall of the matrix.

17. The method according to claim 15, characterized in that The process of metallurgically bonding the outer circumferential surface of the first composite body and the inner wall of the second composite body to form the cylindrical composite body comprises: The second composite body is extruded by an extrusion process, so that the outer peripheral surface of the first composite body and the inner cylinder wall of the second composite body are metallurgically bonded.

18. The method according to any one of claims 14 to 17, characterized in that The forming of the blank into a middle frame comprises: The cylindrical blank is formed into a rectangular plate body by a forging process; The rectangular plate body is formed into a middle frame by using a mechanical processing technology.

19. The method according to any one of claims 14 to 18, characterized in that The method further comprises: An anodizing process is used to prepare an oxide layer on the outer side of the middle frame.

20. An electronic device, characterized in that: A battery comprising a middle frame as claimed in any one of claims 1 to 13, or a middle frame prepared by the method as claimed in any one of claims 14 to 19; The battery is fixed to the battery seating portion.

21. The electronic device according to claim 20, characterized in that: The electronic device also includes a display screen and a back panel; The display screen is arranged on the first surface of the middle plate, and the back plate is arranged on the second surface of the middle plate; The first plate surface and the second plate surface are two opposite plate surfaces of the middle plate.

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