Middle frame structure and mobile terminal

Abstract

The embodiment of the invention provides a middle frame structure and a mobile terminal. The middle frame structure is composed of a compact structure and an interlayer non-compact structure. Wherein the compact structure is composed of a compact area, and the interlayer non-compact structure is composed of a compact area and a non-compact area. The dense area is used for indicating an area with relative density greater than or equal to a first threshold, the non-dense area is used for indicating an area with relative density less than a second threshold, and the first threshold is greater than or equal to the second threshold. By improving the middle frame structure, on one hand, the weight of the middle frame structure can be reduced, so that the whole mobile terminal is further lightened; and on the other hand, the mechanical reliability of the middle frame structure can be enhanced, so that the durability of the mobile terminal is improved, and the user experience is improved.

Description

Technical Field

[0001] The present application relates to the field of terminal technology, and more specifically, to a middle frame structure and terminal device suitable for a mobile terminal. Background Art

[0002] Currently, mobile terminals such as mobile phones on the market are usually sandwich structures, including the front screen, back cover and middle frame of the mobile phone. Among them, the middle frame of the mobile phone is the middle layer of the sandwich structure. It is not only a support for the front screen and back cover of the mobile phone, but also a structural part that carries the battery, camera and motherboard inside the mobile phone. In view of this, the middle frame of the mobile phone must have sufficient structural strength. At the same time, weight is an important indicator of the user experience of mobile terminals such as mobile phones, so lightweight is also a potential requirement for the middle frame of mobile phones.

[0003] The reason why the middle frames of smartphones on the market are made of aluminum alloy is that it has low density, good processing and thermal conductivity, and low cost. However, in the context of the significant thinning of the middle frames of mobile phones, some fatal shortcomings of aluminum alloy have gradually emerged: 1) Insufficient strength: the yield strength of aluminum alloy is low, and if it is hit during use, it is easy to produce irreversible deformation; 2) Insufficient rigidity: It is easy to produce elastic deformation, making it difficult to support large screens, and the mechanical reliability is poor.

[0004] In order to overcome the above defects, the industry has proposed that high-strength and corrosion-resistant titanium alloys can be used to replace aluminum alloy materials to improve the reliability of the middle frame. However, the density of titanium alloy materials is about 4.5g / cm^3, and the density of aluminum alloy materials is 2.7g / cm^3. Direct replacement will increase the weight of the middle frame by 67%, which cannot meet the requirements of lightweight. On this basis, a proposal was made to propose a mobile phone middle frame with a composite titanium alloy outer frame and an aluminum alloy middle plate (CN207386961U). However, the quality of the composite middle frame cannot be controlled to be the same as that of the all-aluminum alloy middle frame, and lightweight cannot be achieved. As mentioned above, the existing technology cannot take into account both the mechanical reliability and lightweight requirements of the mobile phone middle frame. Summary of the invention

[0005] The technical problem to be solved by the present application is to overcome the problems existing in the prior art and provide a middle frame structure that can take into account the characteristics of lightweight and excellent mechanical reliability, thereby greatly improving the user experience of the mobile terminal.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] In the first aspect, the present application provides a middle frame structure, which can be applied to a variety of mobile terminals such as folding mobile phones, straight mobile phones, tablets, PCs, and watches. The middle frame structure is composed of a dense structure and a sandwich non-dense structure, the dense structure is composed of a dense area, the dense area is used to indicate an area with a relative density greater than or equal to a first threshold, the sandwich non-dense structure is composed of a dense area and a non-dense area, the dense area is used to indicate an area with a relative density greater than or equal to the first threshold, and the non-dense area is used to indicate an area with a relative density less than a second threshold, and the first threshold is greater than or equal to the second threshold.

[0008] The middle frame structure provided in the present application adopts a design combining a dense structure and a sandwich non-dense structure. Among them, the non-dense area design introduced by the sandwich non-dense structure reduces the overall density of the middle frame and achieves weight reduction of the overall middle frame structure. At the same time, the dense area design introduced by the dense structure and the dense area design introduced by the sandwich non-dense structure take into account the mechanical reliability of the middle frame structure.

[0009] A possible design is that the sandwich non-dense structure is a three-layer structure designed to be stacked in sequence, including an upper surface layer, a lower surface layer and a middle layer, wherein the upper surface layer and the lower surface layer are dense areas, and the middle layer is a non-dense area.

[0010] A possible design is that the relative density of the non-dense area of ​​the interlayer non-dense structure should also be greater than or equal to a third threshold, and the third threshold is less than the second threshold, that is, the relative density of the non-dense area is greater than or equal to the third threshold and less than the second threshold.

[0011] In a possible design, the relative density of the dense area is greater than or equal to 96%, and the relative density of the non-dense area is greater than or equal to 10% and less than 96%, that is, the first threshold and the second threshold are 96%, and the third threshold is 10%.

[0012] A possible design is that the middle frame structure is a structural member that supports the front screen and the back cover. The middle frame structure includes an outer frame and a middle plate. The outer frame is an annular frame structure, including an upper frame, a lower frame, a left frame and a right frame. Each frame has an inner side surface. The outer frame is arranged around the edge of the middle plate, and the inner side surface of the outer frame is connected to the middle plate through a connection to form an integrated structure.

[0013] A possible design is that the outer frame is composed of a dense structure and a sandwich non-dense structure, and the middle plate is composed of a dense structure and a sandwich non-dense structure.

[0014] In a possible design, the dense structure of the outer frame is arranged in at least one of the following areas: a drop zone, a bending zone, a hole zone, an outer frame surface zone and a button zone. Among them, the drop zone is the four corner parts of the outer frame. The bending zone is the middle part of the left frame and the middle part of the right frame of the outer frame. The hole area is usually distributed on the lower frame of the outer frame. The hole area includes but is not limited to the microphone hole, the charging jack and the speaker hole. The space around the hole area is also a dense area. The outer frame surface area is distributed around the outer frame, which is the part of the outer frame surface inward to a certain thickness. The button area is distributed on the left frame or the right frame of the outer frame, and is used to indicate the power button and volume button area of ​​the mobile terminal.

[0015] It should be noted that the dense structure of the outer frame is set in the above area for the following reasons. In the terminal device usage scenario, when the terminal device falls, the four corners of the outer frame are its main load-bearing parts. When the terminal device is bent, the middle part of the left frame and the right frame of the outer frame is the main load-bearing area. When the user charges the terminal device and uses headphones, the charging port and the headphone port need to cooperate with the user to plug and unplug repeatedly. In addition, the speaker hole and the signal hole are exposed and repeatedly used functional areas. When producing the outer frame of the terminal device, the surface of the outer frame needs to be treated with appearance, that is, dense thickening. The dense thickening treatment specifically refers to polishing the surface of the outer frame to remove a certain thickness, and then thickening the surface on this basis. The thickened area is the dense area. Usually the thickness range is between 0.15-3mm, and the specific thickness will vary according to the actual needs of the product. The thickness of some areas is 0.3mm, and some are 1mm. In addition, the volume button and the power button of the terminal device are repeatedly used functional areas, and it is also necessary to thicken them densely.

[0016] In the middle frame structure, the higher the relative density of the area, the higher its structural strength. Taking the middle frame of a mobile phone as an example, the design of the dense structure enables the corresponding mobile phone frame to have high strength, high rigidity, and excellent bending resistance and drop resistance.

[0017] In a possible design, the interlayer non-dense structure of the outer frame is arranged in other areas outside the dense structure area of ​​the outer frame.

[0018] In a possible design, the middle plate is composed of ribs and a plane area, the ribs are the parts of the middle plate that are higher than the plane, and the ribs are composed of a dense structure.

[0019] In a possible design, the planar area of ​​the middle plate is composed of a sandwich non-dense structure, which includes an upper surface layer, a lower surface layer and an intermediate layer, wherein the upper surface layer and the lower surface layer are dense areas, and the intermediate layer is a non-dense area.

[0020] In a possible design, a designed porous topology is introduced into the non-densified regions of the outer frame and the middle plate, and the porous topology is composed of porous units.

[0021] In a possible design, the porous topological structure introduced in the outer frame and the middle plate adopts a uniform porous structure, and the uniform porous structure is composed of uniform porous units of the same type.

[0022] In a possible design, the porous topological structure introduced into the outer frame and the middle plate adopts a gradient porous structure, and the gradient porous structure is composed of the same type of porous units with a relative density greater than or equal to 10% and less than 96% gradient distribution.

[0023] In a possible design, the porous topological structure introduced by the outer frame and the middle plate adopts a hybrid porous structure, and the hybrid porous structure is composed of two or more different porous units.

[0024] Taking the mobile phone middle frame as an example, compared with the titanium alloy mobile phone middle frame that does not adopt a porous structure, the introduction of a porous structure can not only reduce weight but also control local mechanical properties such as strength and shock absorption performance through an adjustable porous lattice.

[0025] A possible design, the porous units in the porous topological structure include body-centered cubic units, rhombus units, honeycomb porous units, three-periodic minimal surface units, and the relative density of the porous units is greater than or equal to 10% and less than 96%.

[0026] A possible design, the molding methods for producing the outer frame and the middle plate include but are not limited to 3D printing, powder pressing and metal injection.

[0027] Among them, 3D printing (3D printing, 3DP) is a kind of rapid prototyping technology, also known as additive manufacturing (AM), which is a technology that uses digital model files, powders, liquids, sheets and other materials to directly build objects by printing, sintering or melting layer by layer. The main features of 3D printing technology are rapid prototyping, the ability to print complex geometric structures, flexible customization, no need for molds, and can greatly simplify the production process.

[0028] In a possible design, the outer frame and the middle plate are connected to each other through a joint to form an integrated structure, and the connection methods include but are not limited to injection molding, welding, screw connection, riveting connection and glue drawing process.

[0029] In a possible design, the constituent materials of the sandwich non-dense structure of the outer frame include one or more of the following: titanium alloy, titanium-aluminum layered composite material, aluminum alloy, stainless steel, amorphous alloy, and steel-aluminum layered composite material.

[0030] In a possible design, the component materials of the sandwich non-dense structure of the middle plate include one or more of the following: aluminum alloy, aluminum-lithium alloy, copper alloy, magnesium alloy, magnesium-based composite material, copper-based composite material, aluminum-based composite material and magnesium-lithium alloy.

[0031] In a possible design, the middle frame structure is composed of the outer frame and the lower edge of the back cover, and the outer frame and the lower edge of the back cover adopt an integrated metal structure. The lower edge of the back cover introduces a sandwich non-dense structure, including an upper surface layer, a lower surface layer and an intermediate layer, wherein the upper surface layer and the lower surface layer are dense areas, and the intermediate layer is a non-dense area.

[0032] In a second aspect, a mobile terminal is provided, comprising a middle frame structure provided by any possible design in the first aspect.

[0033] In summary, the middle frame structure that combines the dense structure with the sandwich non-dense structure and the mobile terminal using the middle frame structure can simultaneously have the characteristics of high strength, high rigidity, resistance to falling, resistance to bending, and weight reduction.

[0034] These and other aspects of the present application will be more concisely understood in the description of the detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art description are briefly introduced below. Obviously, the following drawings only reflect some embodiments of the present application. For ordinary technicians in this field, other implementation methods of the present application can be obtained based on these drawings without creative work. All these embodiments or implementation methods are within the protection scope of the present application.

[0036] Figure 1 .Schematic diagram of the overall structure of the mobile terminal provided in an embodiment of the present application.

[0037] Figure 2 . Figure 1 A cross-sectional view of the mobile terminal at an AA perspective is shown.

[0038] Figure 3 .Top view of the middle frame structure provided in an embodiment of the present application.

[0039] Figure 4 .A schematic diagram of a mobile phone frame structure provided in an embodiment of the present application.

[0040] Figure 5 .A schematic diagram of the structure of a mobile phone mid-plate provided in an embodiment of the present application.

[0041] Figure 6 .The cross section of the interlayer non-dense structure provided in the embodiment of the present application.

[0042] Reference numerals:

[0043] 100: outer frame 200: back cover 300: front screen 400: middle plate

[0044] 500: Main board 600: Battery 700: Small board 800: Connection

[0045] 110: Drop zone 120: Bending zone 130: Hole zone 140: Frame surface zone

[0046] 160: key area 150: sandwich non-dense structure

[0047] 410: Ribs 420: Plane area

[0048] 1501: upper surface dense area 1502: non-dense area 1503: lower surface dense area DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0050] The specific structure or scheme described in the embodiments of the present application is to more clearly illustrate the technical solution of the embodiments of the present application, and does not constitute a limitation on the technical solution provided in the embodiments of the present application. A person of ordinary skill in the art can know that the technical solution provided in the embodiments of the present application is also applicable to similar technical problems.

[0051] It should be noted that, in the description of the present application, the terms "upper", "lower", "side", "front", "rear", etc. indicate orientations or positional relationships based on the installation, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0052] It should be noted that, in the embodiments of the present application, the same figure mark is used to represent the same component or the same part. For the same parts in the embodiments of the present application, the figure may only mark one of the parts or components as an example. It should be understood that the figure mark also applies to other identical parts or components.

[0053] It should be noted that in the description of this application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0054] It should be noted that the relative density mentioned in this application is also called relative density, which specifically refers to the ratio of measured density to theoretical density. In practice, the measured density and theoretical density can be obtained by Archimedes drainage method and mixing law respectively. Relative density can accurately reflect the density of a specific component metal or alloy, and is the most important indicator for measuring the performance of a specific component metal or alloy.

[0055] The embodiment of the present application provides a middle frame structure, which can be used in terminal products, including the design and processing of middle frame parts in wearable fields such as straight-bar mobile phones, folding mobile phones, tablets, PCs, and watches, but is not limited thereto. A mobile terminal product provided in the embodiment of the present application refers to a portable electronic device having at least one of voice and telephone call functions, information input and information output functions, and information storage functions. The middle frame structure and mobile terminal product provided in the embodiment of the present application are particularly suitable for scenarios that require high strength, high rigidity, drop resistance, bending resistance, and light weight.

[0056] Taking a mobile phone as an example, the middle frame structure provided in the embodiment of the present application and the overall structure of the mobile terminal using the middle frame structure are introduced in detail below.

[0057] Figure 1 is a schematic diagram of the overall structure of a mobile terminal provided in an embodiment of the present application, Figure 2 yes Figure 1 The cross-sectional view of the mobile terminal from the AA perspective is shown in the figure. Currently, the mobile phones sold on the market generally adopt a sandwich structure, that is, the overall structure of the mobile phone consists of three parts, the front screen, the back cover and the mobile phone middle frame. Among them, the mobile phone middle frame is the middle part of the sandwich structure of the mobile terminal, which is used to support the back cover and the front screen of the mobile phone and belongs to the supporting part. The mobile phone middle frame consists of the mobile phone outer frame and the mobile phone middle plate. Figure 1 and Figure 2 As shown, the overall structure of the mobile phone is composed of a front screen 300, a back cover 200 and a mobile phone middle frame. Among them, the figure 100 is the mobile phone outer frame, that is, the exposed part of the mobile phone middle frame in the overall structure of the mobile phone. Figure 2As shown, the mobile phone middle frame is composed of a mobile phone outer frame 100 and a mobile phone middle plate 400. The mobile phone outer frame 100 and the mobile phone back cover 200 together form the shell of the mobile phone, and the mobile phone front screen 300 and the mobile phone shell together form a mounting cavity. The mobile phone front screen 300 is fixedly connected to the front end face of the mobile phone outer frame 100, and the back cover 200 is fixedly connected to the rear end face of the mobile phone outer frame 100. The mobile phone middle plate 400 is placed in the mounting cavity and is not exposed. The mobile phone front screen 300 is attached to the front side of the mobile phone middle plate 400, and the mobile phone back cover 200 is fixedly attached to the rear side of the mobile phone middle plate 400.

[0058] like Figure 2 As shown, the cavity formed between the mobile phone middle plate 400 and the mobile phone back cover 200 contains components such as the main board 500, the battery 600 and the small board 700. The main board 500 is an important component of the mobile terminal, on which various devices constituting the circuit system of the mobile terminal are installed. For example, the main circuit, processor, chip, capacitor, resistor, inductor, interface and plug-in of the mobile terminal are arranged on the main board 500. The battery 600 is an energy storage tool for providing power to the mobile terminal, and is usually composed of three parts: a battery cell, a protection circuit and a shell. The battery 600 is arranged in the battery compartment between the main board 500 and the small board 700. The battery compartment is the area inside the mobile phone for accommodating the battery, and the battery compartment is part of the mobile phone middle plate 400. The small board 700 is located at the bottom of the mobile terminal, and is usually provided with functional components such as a microphone, a speaker, a charging interface, a USB interface, a SIM card interface, a radio frequency interface or an antenna contact. Accordingly, some holes can be opened in the lower frame of the metal outer frame 100 (see Figure 1 ), and used in conjunction with the functional elements of the small board 700 to achieve corresponding functions. For example, a charging hole for a charging plug to be inserted into a charging interface may be provided at the bottom of the outer frame 100. For another example, a sound outlet hole, i.e. a speaker hole, may also be provided at the bottom of the outer frame 100 for the sound of the speaker to pass through. Therefore, the hole is a functional area at the bottom of the outer frame of the mobile phone, and must have the basic characteristics of durability. The main board 500 and the small board 700 are electrically connected through a flexible printed circuit (FPC), which can be clamped between the battery 600 and the back cover 200, or between the battery 600 and the middle plate 400.

[0059] This application is based on the above-mentioned overall terminal structure and provides an improvement on the sandwich structure of the mobile phone. The middle frame structure adopts a design combining a dense structure and a sandwich non-dense structure, so as to take into account the characteristics of light weight and excellent mechanical reliability (bending resistance, drop resistance, high strength). The specific implementation method of this application will be introduced in detail below.

[0060] Figure 3A top view of the mobile phone middle frame structure provided in the embodiment of the present application, such as Figure 3 As shown, the mobile phone middle frame includes a mobile phone outer frame 100 and a mobile phone middle plate 400. The mobile phone outer frame 100 is an annular frame structure, including an upper frame, a lower frame, a left frame and a right frame. The outer frame 100 has an inner side surface. The mobile phone outer frame 100 is arranged around the edge of the mobile phone middle plate 400. The inner side surface of the mobile phone outer frame 100 is connected to the mobile phone middle plate 400 through a connection 800.

[0061] Furthermore, the mobile phone middle frame provided by the present application adopts a design combining a dense structure and a sandwich non-dense structure. Specifically, the mobile phone outer frame 100 adopts a design combining a dense structure and a sandwich non-dense structure, and the mobile phone middle plate 400 also adopts a design combining a dense structure and a sandwich non-dense structure. Among them, the dense structure is composed of a dense area, and the sandwich non-dense structure is composed of a dense area and a non-dense area. The sandwich non-dense structure is a stacked three-layer structure, including an upper surface layer, a lower surface layer and an intermediate layer, wherein the upper surface layer and the lower surface layer are dense areas, and the intermediate layer is a non-dense area.

[0062] In other words, the mobile phone frame 100 includes a dense area and a non-dense area, and the mobile phone middle plate 400 also includes a dense area and a non-dense area. Among them, the non-dense area is distributed in the middle layer of the sandwich non-dense structure, and the dense area is distributed in the dense structure part and the upper surface and lower surface of the sandwich non-dense structure part.

[0063] The dense area specifically refers to an area where the relative density is greater than or equal to the first threshold, and the non-dense area specifically refers to an area where the relative density is less than the second threshold. Obviously, the first threshold is greater than or equal to the second threshold. Furthermore, the relative density of the non-dense area should also be greater than or equal to the third threshold, and the third threshold is less than the second threshold. Therefore, the relative density of the non-dense area is greater than or equal to the third threshold and less than the second threshold, and the relative density of the dense area is greater than or equal to the first threshold. The first threshold and the second threshold can be equal in size.

[0064] In a specific embodiment, the first threshold is 96%, the second threshold is 96%, and the third threshold is 10%. Therefore, the relative density of the dense area is greater than or equal to 96%, and the relative density of the non-dense area is greater than or equal to 10% and less than 96%.

[0065] In a specific embodiment, the first threshold is 95%, the second threshold is 95%, and the third threshold is 10%.

[0066] It should be noted that the above-mentioned first threshold, second threshold, and third threshold may also take other appropriate values. These values ​​may be empirical values ​​or values ​​determined through experiments, and this application does not limit this.

[0067] Optionally, the constituent material of the mobile phone frame 100 can be titanium alloy, titanium-aluminum layered composite material, aluminum alloy, stainless steel, amorphous alloy, steel-aluminum layered composite material.

[0068] The interlayer non-dense structure of the outer frame 100 may be composed of the same material among the above materials, or may be composed of two or more different materials among the above materials.

[0069] Optionally, the component material of the mobile phone middle plate 400 can be aluminum alloy, aluminum-lithium alloy, copper alloy, magnesium alloy, magnesium-based composite material, copper-based composite material, aluminum-based composite material and magnesium-lithium alloy.

[0070] The sandwich non-dense structure of the middle plate 400 may be composed of the same material among the above materials, or may be composed of two or more materials among the above materials.

[0071] The material composition of the mobile phone middle frame can be any combination of the above materials of the mobile phone outer frame and the mobile phone middle plate. For example, the outer frame is made of titanium alloy; the middle plate is made of aluminum alloy. For example, the outer frame is a titanium-aluminum layered composite material, and the middle plate is made of aluminum alloy and magnesium alloy. For another example, the outer frame is made of stainless steel and aluminum alloy, and the middle plate is made of aluminum alloy and copper alloy.

[0072] The design of the above-mentioned dense structure can improve the mechanical reliability of the entire mobile phone middle frame, including bending reliability and drop reliability, thereby extending the service life of the mobile phone middle frame from a structural perspective.

[0073] Figure 4 A schematic diagram of a mobile phone frame structure provided in an embodiment of the present application, such as Figure 4As shown, the black area is the dense structure distribution area of ​​the mobile phone frame 100, including: the drop area 110, the bending area 120, the hole area 130, the outer frame surface area 140 and the key area 160. Among them, the drop area 110 refers to the four corners of the outer frame. This area is the main load-bearing area for falling, so it needs to be reinforced to improve its mechanical reliability. The bending area 120 refers to the middle area of ​​the left and right frames of the outer frame 100. This area is the main load-bearing part when the terminal device is bent. The hole area 130 is located at the bottom of the outer frame 100. This area is mainly some holes configured for the mobile phone frame 100 to cooperate with the functional elements of the small board 700 (microphone, speaker and charging interface, etc.), including but not limited to the headphone jack, speaker hole, charging hole and signal hole. This area belongs to the exposed and repeatedly used functional area. For example, when the user charges the terminal device and uses headphones, the charging hole and the headphone jack need to cooperate with the user to repeatedly plug and unplug, and need to be reinforced to enhance its structural strength. Correspondingly, the space around the hole area 130 also introduces the design of a dense area. The outer frame surface area 140 is the surface around the outer frame to a certain thickness inward. The mobile phone frame 100 will be processed for appearance during production, that is, dense and thickened. Specifically, the mobile phone frame will be polished to remove a certain thickness during production, and the surface will be densely thickened on this basis. The dense and thickened area is the dense area. Among them, the thickness of the dense area is called the dense thickness, and the thickness range is usually between 0.15mm-3mm. The specific thickness will vary according to the actual needs of the product. Some areas have a dense thickness of 0.3mm, some are 1mm, etc. In addition, the button area 160 mainly includes the volume button and the power button, which are repeatedly used, exposed functional areas, and it is also necessary to densify and thicken.

[0074] As mentioned above, in order to meet the requirements of drop resistance, bendability, high strength and high rigidity of the mobile phone middle frame, at least one of the above five areas (drop area 110, bending area 120, hole area 130, outer frame surface area 140, button area 160) should be designed as a dense structure. In other words, the corresponding relative density of at least one of the above five areas should be greater than or equal to the first threshold, thereby enhancing the mechanical reliability of the mobile phone frame.

[0075] Accordingly, other regions outside the dense structure distribution region of the outer frame 100 are the interlayer non-dense structure distribution regions, such as Figure 4 The outer white area is 150.

[0076] In a specific embodiment, the drop area 110, the bending area 120, the hole area 130, the frame surface area 140 and the button area 160 of the mobile phone frame are all dense structure distribution areas, and other areas are interlayer non-dense structure distribution areas.

[0077] Figure 5A schematic diagram of a mobile phone mid-plate structure provided in an embodiment of the present application is shown in FIG. Figure 5 As shown, the black area is the dense structure distribution area of ​​the mobile phone middle plate 400, and the white area is the interlayer non-dense structure distribution area of ​​the mobile phone middle plate 400. The chamber formed between the mobile phone middle plate 400 and the mobile phone back cover 200 contains components such as the main board 500, the battery 600 and the small board 700. The mobile phone middle plate 400 can be divided into ribs 410 and a plane area 420. The ribs 410 are the parts of the mobile phone middle plate 400 that are higher than the plane, which play the role of dividing the storage areas of various components and supporting them. The ribs 410 adopt a dense structure design. In other words, the ribs 410 are all dense areas, and the relative density of the ribs 410 is greater than or equal to the first threshold. The plane area 420 is the thickness part of the mobile phone middle plate 400, that is, the area of ​​the mobile phone middle plate 400 except the ribs 410. The plane area 420 adopts a sandwich non-dense structure design, including an upper surface layer, a lower surface layer and a middle layer, wherein the upper surface layer and the lower surface layer are dense areas, and the middle layer is a non-dense area.

[0078] Figure 6 The cross section of the interlayer non-dense structure provided in the embodiment of the present application is as follows: Figure 6 As shown, the interlayer non-dense structure is divided into three layers, and the interlayer non-dense structure is a three-layer design stacked in sequence, including an upper surface layer, a lower surface layer and an intermediate layer, wherein the upper surface layer is a dense region 1501, the lower surface layer is a dense region 1503, the relative density of the upper surface layer and the lower surface layer is greater than or equal to the first threshold, and the intermediate layer is a non-dense region 1502, and the relative density of the intermediate layer is greater than or equal to the third threshold and less than the second threshold. Among them, the non-dense region can introduce a topological porous structure design, and the porous structure is composed of porous units, and the relative density of the porous units is greater than or equal to the third threshold and less than the second threshold.

[0079] Optionally, the porous element can be a body-centered cubic element, a rhombus element, a honeycomb porous element, a three-periodic minimal surface element

[0080] The introduction of the above-mentioned topological porous structure can reduce the overall density of the mobile phone middle frame, thereby reducing the weight of the mobile phone middle frame and meeting the user group's requirements for lightweight mobile phones.

[0081] Furthermore, a middle frame structure is composed of an outer frame 100 and the lower edge of a back cover 200, and the outer frame 100 and the lower edge of the back cover 200 adopt an integrated metal structure, that is, they are machined from the same piece of metal. Among them, the outer frame 100 adopts a design combining a dense structure with an interlayer non-dense structure, and the lower edge of the back cover 200 introduces a design of an interlayer non-dense structure, that is, the upper surface layer of the lower edge of the back cover 200 is a dense area 1501, the lower surface layer of the lower edge of the back cover 200 is a dense area 1503, and the middle layer is a non-dense area 1502.

[0082] Optionally, the material of the lower edge of the back cover 200 can be one or more of aluminum alloy, titanium alloy, stainless steel, amorphous alloy, titanium-aluminum layered composite material, and steel-aluminum layered composite material.

[0083] Several specific embodiments are provided below to further illustrate the middle frame structure of the present application.

[0084] One embodiment of the present application provides a structural design of a mobile phone middle frame, that is, a combined structure of a mobile phone outer frame 100 and a mobile phone middle plate 400. The drop zone 110, the bending zone 120, the hole zone 130 (such as a speaker hole, an earphone hole, a charging hole), and the key zone 160 of the outer frame 100 are designed as a dense structure, that is, the relative density is greater than 97%, and the remaining areas of the outer frame 100 are designed as a sandwich non-dense structure. A uniform porous structure is introduced into the middle layer (non-dense area) of the sandwich non-dense structure, that is, it is composed of uniform porous units (such as body-centered cubic units, rhombus units, honeycomb porous units, three-period minimal surface units), and the relative density of the porous units is 10%-95%. The ribs 410 of the middle plate 400 are designed with a dense structure, and the relative density of the ribs 410 is greater than 97%. The plane area 420 of the middle plate 400 adopts a sandwich non-dense structure, and the middle layer (non-dense area) of the sandwich non-dense structure introduces a uniform porous structure, that is, it is composed of uniform porous units (such as body-centered cubic units, rhombus units, honeycomb porous units, and three-period minimal surface units), and the relative density of the porous units is 10%-95%. The inner side of the outer frame 100 and the middle plate 400 are connected through the connection 800, and the connection 800 is provided with a plurality of embedded structures, which are shown as bosses on the side of the outer frame 100 and grooves on the side of the middle plate 400. The gap between the outer frame 100 and the middle plate 400 after splicing is 0.1±0.05mm.

[0085] One embodiment of the present application provides a structural design of a mobile phone middle frame, that is, a combined structure of a mobile phone outer frame 100 and a mobile phone middle plate 400. The drop zone 110, the bending zone 120, the hole zone 130 (such as a speaker hole, an earphone hole, a charging hole), and the key zone 160 of the outer frame 100 are designed as a dense structure (relative density>97%), and the remaining areas of the outer frame 100 are designed as a sandwich non-dense structure. The upper and lower surface layers of the sandwich non-dense structure are dense areas with a relative density>97%, and the middle layer (non-dense area) of the sandwich non-dense structure introduces a gradient porous structure, that is, it is composed of gradient porous units of the same type (such as body-centered cubic units, rhombus units, honeycomb porous units, three-period minimal surface units), and the relative density of the porous units is distributed in a gradient from 10% to 95%, thereby achieving special adjustable mechanical performance, such as strength, shock absorption performance, etc. The ribs 410 of the middle plate 400 are designed with a dense structure, and the relative density of the ribs 410 is greater than 97%. The plane area 420 of the middle plate 400 adopts a sandwich non-dense structure, and the middle layer (non-dense area) of the sandwich non-dense structure introduces a uniform porous structure, that is, it is composed of uniform porous units (such as body-centered cubic units, rhombus units, honeycomb porous units, and three-period minimal surface units), and the relative density of the porous units is 10%-95%. The inner side of the outer frame 100 and the middle plate 400 are connected through the connection 800, and the connection 800 is provided with a plurality of embedded structures, which are shown as bosses on the side of the outer frame 100 and as grooves on the side of the middle plate 400. The gap between the outer frame 100 and the middle plate 400 after splicing is 0.1±0.05mm.

[0086] One embodiment of the present application provides a structural design of a mobile phone middle frame, that is, a combined structure of a mobile phone outer frame 100 and a mobile phone middle plate 400. The drop zone 110, the bending zone 120, the hole zone 130 (such as a speaker hole, an earphone hole, a charging hole), and the key zone 160 of the outer frame are designed as a dense structure (relative density>97%), and the remaining areas of the outer frame 100 are designed as a sandwich non-dense structure. The upper and lower surface layers of the sandwich non-dense structure are dense areas, and their relative density is>97%. The middle layer (non-dense area) of the sandwich non-dense structure introduces a mixed porous structure, that is, it is composed of 2-3 different porous units (such as body-centered cubic units, rhombus units, honeycomb porous units, and three-period minimal surface units), so that the local mechanical properties, such as strength and shock absorption performance, are controlled through adjustable porous lattice organization. The ribs 410 of the middle plate 400 adopt a dense structure, and the relative density of the ribs 410 is greater than 97%. The plane area 420 of the middle plate 400 adopts a sandwich non-dense structure, and the middle layer (non-dense area) of the sandwich non-dense structure introduces a uniform porous structure, that is, it is composed of uniform porous units (such as body-centered cubic units, rhombus units, honeycomb porous units, three-period minimal surface units), and the relative density of the porous units is 10%-95%. The inner side of the outer frame 100 and the middle plate 400 are connected through the connection 800, and the connection 800 is provided with multiple embedded structures. The embedded structure is a boss on the side of the outer frame 100 and a groove on the side of the middle plate 400. The gap between the outer frame 100 and the middle plate 400 after splicing is 0.1±0.05mm.

[0087] Those skilled in the art will appreciate that in one or more of the above embodiments, the functions described herein can be realized by combining and applying the above different types of porous structures in the non-dense areas of the mobile phone frame 100 and the mobile phone middle plate 400. For example, a uniform porous structure is used in the non-dense area of ​​the mobile phone frame 100, and a mixed porous structure is used in the non-dense area of ​​the corresponding mobile phone middle plate 400; a gradient porous structure is used in the non-dense area of ​​the mobile phone frame 100, and a uniform porous structure is used in the non-dense area of ​​the corresponding mobile phone middle plate 400, or other combinations.

[0088] The following is an introduction to the preparation process of the middle frame structure provided in the embodiment of the present application. The middle frame preparation process mainly includes three steps:

[0089] Step 1: Make a mobile phone frame 100.

[0090] Specifically, first, a certain production process is selected to form the mobile phone frame 100, and the production process may be 3D printing, powder pressing, metal injection or other molding methods; secondly, the formed mobile phone frame 100 is subjected to heat treatment, further machining and sandblasting; finally, the mobile phone frame 100 is polished and subjected to PVD coating on the exterior surface;

[0091] Step 2: Make the mobile phone middle plate 400.

[0092] Specifically, firstly, a certain method is selected to form the mobile phone middle plate 400, and the forming method may be 3D printing, powder pressing, metal injection or other forming methods; secondly, the formed mobile phone middle plate 400 is heat treated; finally, the mobile phone middle plate 400 after the heat treatment is completed is machined and sandblasted;

[0093] Step 3: Splice the mobile phone frame 100 and the mobile phone middle plate 400.

[0094] Specifically, the mobile phone frame 100 produced in step 1 and the mobile phone middle plate 400 produced in step 2 are spliced ​​using a certain connection method, and the connection method can be injection molding connection, screw connection, rivet connection, or welding.

[0095] A specific embodiment will be provided below to introduce in detail the preparation process of the mobile phone middle frame. The middle frame structure involved in this embodiment includes a mobile phone outer frame 100 and a mobile phone middle plate 400 made of metal. Among them, in this embodiment, the mobile phone middle frame 100 adopts a 3D printing molding method. More specifically, the mobile phone outer frame uses a titanium alloy raw material with a particle size of 15-53μm, and the mobile phone middle plate uses an aluminum alloy raw material with a particle size of 15-53μm. Furthermore, injection molding is used to realize the connection between the mobile phone outer frame 100 and the mobile phone middle plate 400, and the plastic material used for injection molding uses 30% glass fiber reinforced PPA.

[0096] The three-dimensional model of the outer frame is input into the powder bed laser 3D printer for slicing. After slicing, the titanium alloy raw material powder with a particle size of 15-53μm is used for printing. The printing parameters are as follows: the substrate is preheated to 100℃, the laser power is 300W, the scanning speed is 800-1200mm / s, the scanning spacing is 0.1mm, the powder layer thickness is 20-40μm, and the protective atmosphere is high-purity argon. After printing is completed and the powder on the workpiece is cleaned, it is sent to the heat treatment furnace for annealing at 480-550℃ for 4-8 hours. After the heat treatment is completed, the workpiece is removed from the substrate using the electric spark wire cutting process, and the workpiece is sandblasted with 220 mesh quartz sand to remove the powder adhering to the surface, and the surface roughness is controlled to be Ra6.3~12.5μm. Finally, the appearance of the titanium alloy outer frame is mechanically polished and then chemically polished. After completion, the appearance of the titanium alloy outer frame is PVD coated.

[0097] The 3D model of the middle plate is input into the powder bed laser 3D printer for slicing. After slicing, the aluminum alloy raw material powder with a particle size of 15-53μm is used for printing. The printing parameters are as follows: the substrate is preheated to 100℃, the laser power is 200W, the scanning speed is 800-1200mm / s, the scanning spacing is 0.12mm, the powder layer thickness is 20-40μm, and the protective atmosphere is high-purity argon. After printing is completed and the powder on the workpiece is cleaned, it is sent to the heat treatment furnace for annealing at 300-400℃ for 2-4 hours. After the heat treatment is completed, the workpiece is removed from the substrate using the electric spark wire cutting process, and the workpiece is sandblasted with 220 mesh quartz sand to remove the powder adhering to the surface, and the surface roughness Ra is controlled to be ≥6.3μm.

[0098] The outer frame 100 and the middle plate 400 are installed in the injection mold and spliced ​​with each other. The plastic material uses 30% glass fiber reinforced PPA, the injection temperature uses 220-280°C, the injection pressure: 60-100MPa, and the filling rate is 50mm / s. After completion, a 3D printed porous titanium aluminum middle frame is obtained.

[0099] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation methods of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made on the basis of the technical solutions of the present application should be included in the scope of protection of the present application.

Claims

1. A middle frame structure, characterized in that: The middle frame structure is composed of a dense structure and an interlayer non-dense structure, the dense structure is a dense area, and the interlayer non-dense structure is composed of the dense area and the non-dense area, the dense area is used to indicate an area with a relative density greater than or equal to a first threshold, and the non-dense area is used to indicate an area with a relative density less than a second threshold, and the first threshold is greater than or equal to the second threshold.

2. The middle frame structure according to claim 1, characterized in that: The interlayer non-dense structure is a three-layer structure designed to be stacked in sequence, including an upper surface layer, a lower surface layer and a middle layer, the upper surface layer is a dense area (1501), the lower surface layer is a dense area (1503), and the middle layer is a non-dense area (1502).

3. The middle frame structure according to claim 1 or 2, characterized in that: The relative density of the non-dense region (1502) of the interlayer non-dense structure is greater than or equal to a third threshold, and the third threshold is less than the second threshold.

4. The middle frame structure according to claim 3, characterized in that: The first threshold and the second threshold are 96%, and the third threshold is 10%.

5. The middle frame structure according to any one of claims 1 to 4, characterized in that: The middle frame structure is a structural component that supports the back cover (200) and the front screen (300). The middle frame structure is composed of an outer frame (100) and a middle plate (400). The outer frame is an annular frame structure, including an upper frame, a lower frame, a left frame and a right frame. The outer frame (100) is arranged around the edge of the middle plate (400), and the inner side surface of the outer frame (100) is connected to the middle plate (400) through a connection (800).

6. The middle frame structure according to claim 5, characterized in that: The outer frame (100) and the middle plate (400) are both composed of the dense structure and the sandwich non-dense structure.

7. The middle frame structure according to claim 6, characterized in that: The compact structure of the outer frame (100) is arranged in at least one of the following areas: a drop zone (110), a bending zone (120), a hole zone (130), an outer frame surface zone (140), and a key zone (160), wherein the drop zone (110) is the four corner parts of the outer frame (100), the bending zone (120) is the middle part of the left frame and the right frame of the outer frame (100), the hole zone (130) is distributed on the lower frame of the outer frame (100), the outer frame surface zone (140) is distributed on the surface of the outer frame (100) to a certain thickness inward, and the key zone (160) is distributed on the left frame and the right frame of the outer frame (100).

8. The middle frame structure according to claim 6 or 7, characterized in that: The interlayer non-dense structure of the outer frame (100) is arranged in other areas outside the dense structure area of ​​the outer frame (100).

9. The middle frame structure according to any one of claims 6 to 8, characterized in that: The middle plate (400) is composed of ribs (410) and a plane area (420), wherein the ribs (410) are portions of the middle plate (400) that are higher than the plane, the ribs (410) are composed of a dense structure, and the plane area (420) is composed of a sandwich non-dense structure.

10. The middle frame structure according to any one of claims 6 to 9, characterized in that: The non-dense regions (1502) of the outer frame (100) and the middle plate (400) introduce a designed porous topological structure, wherein the porous topological structure is composed of porous units.

11. The middle frame structure according to claim 10, characterized in that: The porous topological structure is a uniform porous structure, and the uniform porous structure is composed of uniform porous units of the same kind.

12. The middle frame structure according to claim 10, characterized in that: The porous topological structure is a gradient porous structure, which is composed of the same type of porous units with a relative density greater than or equal to 10% and less than 96% gradient distribution.

13. The middle frame structure according to claim 10, characterized in that: The porous topological structure is a mixed porous structure, which is composed of two or more different porous units.

14. The middle frame structure according to any one of claims 10 to 13, characterized in that: The porous units in the porous topological structure include body-centered cubic units, rhombus units, honeycomb porous units, and three-periodic minimal surface units.

15. The middle frame structure according to any one of claims 5 to 14, characterized in that: The outer frame (100) and the middle plate (400) are prepared and molded by one or more of 3D printing, powder pressing, and metal injection.

16. The middle frame structure according to any one of claims 5 to 15, characterized in that: The inner side surface of the outer frame (100) and the middle plate (400) are connected to each other through a connection (800) to form an integrated structure, and the connection method includes one or more of injection molding, welding, screw connection, riveting connection and glue drawing process.

17. The middle frame structure according to any one of claims 5 to 16, characterized in that: The constituent materials of the sandwich non-dense structure of the outer frame (100) include one or more of the following: titanium alloy, titanium-aluminum layered composite material, aluminum alloy, stainless steel, amorphous alloy, and steel-aluminum layered composite material.

18. The middle frame structure according to any one of claims 5 to 16, characterized in that: The constituent materials of the sandwich non-dense structure of the middle plate (400) include one or more of the following: aluminum alloy, aluminum-lithium alloy, copper alloy, magnesium alloy, magnesium-based composite material, copper-based composite material, aluminum-based composite material and magnesium-lithium alloy.

19. The middle frame structure according to any one of claims 1 to 4, characterized in that: The middle frame structure is composed of an outer frame (100) and the lower edge of a back cover (200), the lower edges of the outer frame (100) and the back cover (200) adopt an integrated metal structure, and the lower edge of the back cover (200) introduces the interlayer non-dense structure.

20. A mobile terminal, characterized in that: It comprises the middle frame structure described in any one of claims 1-19.

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