Middle frame manufacturing method

Abstract

A middle frame manufacturing method, comprising the following steps: material acquisition: acquiring a first material for manufacturing a frame, wherein the first material has a first coefficient of thermal expansion; and acquiring a second material used for manufacturing a middle plate, wherein the second material has a second coefficient of thermal expansion; forming: manufacturing the first material into a preset shape so as to acquire a frame; spraying: machining a roughened layer on the first material that has been manufactured into the preset shape, and using a spraying process to manufacture a spraying layer on the roughened layer, wherein the spraying layer has a third coefficient of thermal expansion, and a difference value between the third coefficient of thermal expansion and the second coefficient of thermal expansion is within a preset range; and bonding: bonding the second material onto the spraying layer, and using the second material as a middle plate, thereby obtaining a middle frame. In the middle frame prepared by the method, the connecting strength between the middle plate and the frame is improved, and the overall waterproof performance of the middle frame is also improved.

Description

A method for preparing a middle frame Technical Field

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

[0002] The phenomenon in which the volume or length of an object expands with changes in temperature is called thermal expansion. The essence of thermal expansion is that the average distance between crystal lattice structures changes with temperature. The thermal expansion capacity of an object is measured by the change in length, area or volume caused by a unit temperature change under constant pressure. This is the thermal expansion coefficient. The thermal expansion coefficient is one of the main physical properties of a material and is an important indicator of its thermal stability. Technical issues

[0003] During the preparation and use of existing composite materials, due to the different thermal expansion coefficients between the raw materials of the composite materials, the material with the larger thermal expansion coefficient will cool and shrink more than the other material after preparation, which may form defects such as micropores at the interface between the two materials, thereby affecting the waterproof performance of the interface. In addition, if the interface bonding force between the raw materials of the composite material is large, internal stress will be generated, thereby affecting the bonding strength and subsequent use of the composite material. For example, the existing electronic device middle frame structure is made of metals such as titanium alloy / stainless steel to meet the needs of appearance, but its cost is relatively high. To save costs, a composite material of titanium alloy / stainless steel and magnesium / aluminum alloy has been developed. The use of this composite material is low-cost and also meets the needs of appearance. In addition, this composite material directly combines titanium alloy / stainless steel with magnesium / aluminum alloy through a die-casting process. However, due to the different thermal expansion coefficients of titanium alloy, stainless steel and magnesium / aluminum alloy, the shrinkage of the different materials at room temperature is inconsistent compared to when they are die-casted at high temperature, thereby affecting the bonding strength and waterproof performance of the entire frame. Technical Solutions

[0004] The embodiments of the present application provide a method for preparing a middle frame, which is used to solve the problems in the prior art of poor waterproof performance and low bonding strength of the middle frame caused by inconsistent shrinkage of the materials when materials with different thermal expansion coefficients are directly bonded.

[0005] In an embodiment of the present application, the middle frame preparation method includes the following steps:

[0006] Materials: a first material for preparing a frame, wherein the first material has a first thermal expansion coefficient; a second material for preparing a middle plate, wherein the second material has a second thermal expansion coefficient;

[0007] Molding: preparing the first material into a preset shape to obtain a frame;

[0008] Spraying: processing a roughened layer on the first material that has been prepared into a preset shape, and forming a sprayed layer on the roughened layer using a spraying process, wherein the sprayed layer has a third thermal expansion coefficient, and the difference between the third thermal expansion coefficient and the second thermal expansion coefficient is within a preset range;

[0009] Bonding: bonding the second material to the sprayed layer so that the second material serves as a middle plate, thereby obtaining a middle frame.

[0010] As a further optional solution of the middle frame manufacturing method, an absolute value of a difference between the third thermal expansion coefficient and the second thermal expansion coefficient is less than or equal to 15% of the third thermal expansion coefficient.

[0011] As a further optional solution of the middle frame preparation method, in the bonding step, the second material is bonded to the spray coating layer by a die-casting process.

[0012] As a further optional scheme of the middle frame preparation method, in the molding step, when the first material is prepared into a preset shape, a first fastening structure is formed on the first material, and the spray layer at least covers the first fastening structure; the second material forms a second fastening structure after die-casting, and the second fastening structure is cooperatively connected with the first fastening structure.

[0013] As a further optional solution of the middle frame preparation method, the first fastening structure is configured as a tenon and / or a tenon groove; the second fastening structure is correspondingly configured as a tenon groove and / or a tenon.

[0014] As a further optional solution of the middle frame preparation method, the die-casting process includes:

[0015] The first material is heated so that a first expansion amount of the first material due to heat expansion is equal to a second expansion amount of the second material in a molten state relative to room temperature, or the difference between the first expansion amount and the second expansion amount is within a preset range; the second material in a molten state is injected into a mold so that it is combined with the first material to form the middle plate.

[0016] As a further optional solution of the middle frame preparation method, the spray coating is a metal spray coating, and the metal spray coating is composed of a plurality of metal particles.

[0017] As a further optional solution of the middle frame manufacturing method, the first material and the second material are both metal materials.

[0018] As a further optional solution of the middle frame preparation method, the first material is a non-metallic material, and the second material is a metallic material.

[0019] As a further optional solution of the middle frame preparation method, the first material is set to ceramic. Beneficial effects

[0020] Implementing the embodiments of this application will have the following beneficial effects:

[0021] The present application uses a spray coating process to prepare a spray coating on a first material. The spray coating can be firmly fixed on the first material. At this time, the spray coating and the first material can be regarded as a whole. Then the second material is prepared on the spray coating and connected to the spray coating. The spray coating can be thermally deformed synchronously or nearly synchronously with the second material, so that the internal stress generated between the spray coating and the second material is small, and the possibility of generating gaps is reduced, thereby improving the connection strength between the first material and the second material, and improving the airtightness of the joint between the first material and the second material. In other words, the connection strength between the middle plate and the frame of the middle frame is improved, and the overall waterproof performance of the middle frame is also improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] in:

[0024] FIG1 is a schematic flow chart of a method for preparing a middle frame in one embodiment of the present application;

[0025] FIG. 2 is an experimental data diagram showing the difference between the third thermal expansion coefficient and the second thermal expansion coefficient and the connection strength in one embodiment of the present application. Modes for Carrying Out the Invention

[0026] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] The embodiments of the present application provide a method for preparing a middle frame, which is used to solve the problems in the prior art of poor waterproof performance and low bonding strength of the middle frame caused by inconsistent shrinkage of the materials when materials with different thermal expansion coefficients are directly bonded.

[0028] Referring to FIG1 , a method for preparing a middle frame provided in an embodiment of the present application includes the following steps:

[0029] Materials: a first material for preparing a frame is taken, the first material having a first thermal expansion coefficient; a second material for preparing a middle plate is taken, the second material having a second thermal expansion coefficient;

[0030] Molding: preparing the first material into a preset shape to obtain a frame;

[0031] Spraying: a roughened layer is formed on the first material that has been prepared into a preset shape, and a sprayed layer is formed on the roughened layer by a spraying process, wherein the sprayed layer has a third thermal expansion coefficient, and the difference between the third thermal expansion coefficient and the second thermal expansion coefficient is within a preset range;

[0032] Bonding: Bonding a second material to the spray layer so that the second material serves as a middle plate.

[0033] FIG2 shows experimental data on the bonding strength of the joints between different first and second materials with and without a spray coating. In the table, the percentage of the first difference represents the percentage of the ratio of the absolute value of the difference between the first and third thermal expansion coefficients to the third thermal expansion coefficient, and the percentage of the second difference represents the percentage of the ratio of the absolute value of the difference between the second and third thermal expansion coefficients to the third thermal expansion coefficient.

[0034] Comparing Groups 1 with 2 or 3, or with Groups 4 with 5 or 6, or with Groups 7 with 8 or 9, it can be seen that providing a spray coating on the first material can significantly improve the bond strength between the first and second materials. Comparing Groups 2 with 3 and with Groups 5 with 6, it can be found that whether the third thermal expansion coefficient is between the first and second thermal expansion coefficients is not a key factor affecting the bond strength between the spray coating and the second material. Instead, the bond strength is significantly affected by the material of the spray coating. In the comparisons between Groups 2 and 3 and between Groups 5 and 6, brass performed better as the material for the spray coating than aluminum. Therefore, it can be concluded that the value of the third thermal expansion coefficient can be between the first and second thermal expansion coefficients, that is, greater than or equal to the smaller value of the first and second thermal expansion coefficients, and less than or equal to the larger value of the first and second thermal expansion coefficients. It can also be outside the range of the first and second thermal expansion coefficients, that is, less than the smaller value of the first and second thermal expansion coefficients, or greater than the larger value of the first and second thermal expansion coefficients. The key point is that the third thermal expansion coefficient should be close to or equal to the second thermal expansion coefficient so that the difference in volume shrinkage between the sprayed layer and the second material during the cooling process is not too large, thereby reducing the internal stress between the two and avoiding the formation of gaps at the joint, thereby improving the bonding quality. This is the aforementioned "the difference between the third thermal expansion coefficient and the second thermal expansion coefficient is within a preset range." It should be noted that, as can be seen from the table, the bonding strength is not only affected by the material of the spray coating, but is also obviously related to the difference between the second thermal expansion coefficient and the third thermal expansion coefficient. The quality requirements of different batches of products are also different. Therefore, the allowable difference range between the second thermal expansion coefficient and the third thermal expansion coefficient can be determined by those skilled in the art based on actual conditions and is not specifically limited here.

[0035] The present application uses a spray coating process to prepare a spray coating on a first material. The spray coating can be firmly fixed on the first material. At this time, the spray coating and the first material can be regarded as a whole. Then the second material is prepared on the spray coating and connected to the spray coating. The spray coating can be thermally deformed synchronously or nearly synchronously with the second material, so that the internal stress generated between the spray coating and the second material is small, and the possibility of generating gaps is reduced, thereby improving the connection strength between the first material and the second material, and improving the airtightness of the joint between the first material and the second material. In other words, the connection strength between the middle plate and the frame of the middle frame is improved, and the overall waterproof performance of the middle frame is also improved.

[0036] In one embodiment, the absolute value of the difference between the third thermal expansion coefficient and the second thermal expansion coefficient is less than or equal to 15% of the third thermal expansion coefficient. It should be noted that this value is only a preferred value obtained based on experimental data.

[0037] In one embodiment, in the bonding step, the second material is bonded to the sprayed layer by a die-casting process.

[0038] The advantages of using the die-casting process in the combining step are: it can produce metal parts with complex shapes, clear contours, thin walls and deep cavities; the die-cast parts have high dimensional accuracy and good interchangeability; the material utilization rate is high; and the production efficiency is high.

[0039] In a specific embodiment, in the molding step, when the first material is prepared into a preset shape, a first fastening structure is formed on the first material, and the spray layer at least covers the first fastening structure; the second material is formed into a second fastening structure after die-casting, and the second fastening structure is cooperatively connected with the first fastening structure.

[0040] The purpose of setting the first fastening structure and the second fastening structure is to further improve the bonding strength between the first material and the second material. Generally speaking, after setting the first fastening structure and the second fastening structure, the bonding strength can be increased to more than 10 times that of the solution without setting it.

[0041] In a more specific embodiment, the first fastening structure is configured as a tenon and / or a tenon groove; the second fastening structure is correspondingly configured as a tenon groove and / or a tenon.

[0042] In a specific embodiment, the die-casting process includes:

[0043] The first material is heated so that a first expansion amount of the first material due to heat expansion is equal to a second expansion amount of the second material in a molten state relative to room temperature, or the difference between the first expansion amount and the second expansion amount is within a preset range; the second material in a molten state is injected into a mold so that it combines with the first material to form a middle plate.

[0044] In this step, the value of the first expansion amount is related to the type of the second material used in the die-casting process. Specifically, since the size of the first material (frame) is fixed, and the second material (middle plate) needs to be connected with the first material, the size of the second material at room temperature is also fixed. During the die-casting process, the second material will be in a molten state and its volume will expand. The purpose of heating the first material is to make the first expansion amount of the first material equal to or close to the second expansion amount of the second material. In other words, the contraction amount of the frame and the middle plate after cooling is also equal or close, thereby effectively reducing the generation of internal stress. The specific difference range between the first expansion amount and the second expansion amount can be determined by technical personnel in this field according to the specific quality standards of different batches of products, and no excessive restrictions are made here.

[0045] For the specific temperature value that the frame needs to rise, taking the first expansion amount of the frame and the second expansion amount of the middle plate as an example, let the thermal expansion coefficient of the frame (first material) be A, the thermal expansion coefficient of the middle plate (second material) be B, the room temperature be C, the temperature of the frame after rising be X, and the temperature of the middle plate in the molten state be Y, then the following formula can be obtained: (XC)×A=(YC)×B

[0046] By calculating the value of X, you can know how many degrees the frame needs to be heated.

[0047] If the difference between the first expansion amount of the frame and the second expansion amount of the middle plate is limited to a percentage range, and the number D (which can be positive or negative) is used to represent this percentage, the formula becomes: (XC)×A=(YC)×B×(100%+D)

[0048] Similarly, by calculating the X value, you can know how many degrees the frame needs to be heated.

[0049] It is particularly important to note that if the temperature of the frame exceeds the melting point of the frame or the melting point of the spray layer when the first expansion amount is equal to the second expansion amount, the first expansion amount should not be equal to the second expansion amount to avoid damaging the structure of the frame or damaging the spray layer.

[0050] In one embodiment, the second material is bonded to the sprayed layer by a brazing process.

[0051] In one embodiment, the sprayed layer is a metal sprayed layer, and the metal sprayed layer is composed of a plurality of metal particles.

[0052] In a specific embodiment, the material of the sprayed layer is preferably aluminum or brass.

[0053] In a specific embodiment, the diameter of the metal particles is 2-100 μm.

[0054] In one embodiment, the first material and the second material are both metal materials.

[0055] In another embodiment, the first material is a non-metallic material, and the second material is a metallic material.

[0056] In a specific embodiment, the first material is ceramic.

[0057] Using ceramic as the frame material gives the frame a texture as smooth as jade, hard and wear-resistant. The frame is durable and ceramic will not shield the signal, which facilitates the design and layout of the antenna, improves the stability of signal transmission, and enhances the user experience.

[0058] The ceramic frame can be prepared by the following production method: ceramic powder containing a binder component is placed in an injection molding machine, heated to transform into a viscous melt, then injected into a mold, and demolded after cooling to obtain a ceramic green body. A first fastening structure is formed on the ceramic green body. The binder component in the ceramic green body is then removed by physical or chemical methods to obtain a ceramic green body. After sintering the ceramic green body, a ceramic frame can be obtained.

[0059] The advantages of using injection molding to produce ceramic blanks are: high precision of molded products, uniform green density, high green strength, good consistency of product quality after sintering, and no need for machining or only a small amount of machining after sintering, thereby reducing expensive ceramic processing costs; the molding process has a high degree of mechanization and automation, a short molding cycle, and convenient management and control of the production process, making it easy to achieve large-scale and large-scale production; the molded ceramic products have extremely high dimensional accuracy and surface finish, with a surface finish of up to 5um.

[0060] The obtained ceramic frame can also be further processed to improve its dimensional accuracy, surface properties and to process various types of holes, holes and groove structures required for the frame. The methods for processing the ceramic frame include at least one of abrasive processing, plastic processing, chemical processing, electrical processing, composite processing and optical processing. Among them, the abrasive processing methods include but are not limited to grinding processing, polishing processing, sand belt processing, roller processing, ultrasonic processing, shot peening processing, and viscoelastic flow processing; the plastic processing methods include but are not limited to diamond plastic processing and diamond plastic grinding; the chemical processing methods include but are not limited to etching, chemical grinding, and chemical polishing; the electrical processing methods include but are not limited to electrical discharge machining, electron beam machining, ion beam machining, and plasma machining; the composite processing methods include but are not limited to photolithography processing, ELID grinding, ultrasonic grinding, ultrasonic grinding, and ultrasonic electrical discharge machining; the optical processing methods include but are not limited to laser processing.

Claims

1. A method for preparing a middle frame, characterized in that: The following steps are involved: Materials: taking a first material for preparing a frame, the first material having a first thermal expansion coefficient; taking a second material for preparing a middle plate, the second material having a second thermal expansion coefficient; Forming: preparing the first material into a preset shape to obtain a frame; Spraying: processing a roughened layer on the first material that has been prepared into a preset shape, and preparing a sprayed layer on the roughened layer by a spraying process, wherein the sprayed layer has a third thermal expansion coefficient, and the difference between the third thermal expansion coefficient and the second thermal expansion coefficient is within a preset range; Bonding: bonding the second material to the spray layer so that the second material serves as a middle plate, thereby obtaining a middle frame.

2. The method for preparing the middle frame according to claim 1, characterized in that: An absolute value of a difference between the third thermal expansion coefficient and the second thermal expansion coefficient is less than or equal to 15% of the third thermal expansion coefficient.

3. The method for preparing the middle frame according to claim 1, characterized in that: In the bonding step, the second material is bonded to the sprayed layer through a die-casting process.

4. The method for preparing the middle frame according to claim 3, characterized in that: In the molding step, when the first material is prepared into a preset shape, a first fastening structure is formed on the first material, and the spray layer at least covers the first fastening structure; the second material forms a second fastening structure after die-casting, and the second fastening structure is cooperatively connected with the first fastening structure.

5. The method for preparing the middle frame according to claim 4, characterized in that: The first fastening structure is configured as a tenon and / or a tenon groove; the second fastening structure is correspondingly configured as a tenon groove and / or a tenon.

6. The method for preparing the middle frame according to claim 3, characterized in that: The die casting process includes: The first material is heated so that a first expansion amount of the first material due to heat expansion is equal to a second expansion amount of the second material in a molten state relative to room temperature, or the difference between the first expansion amount and the second expansion amount is within a preset range; the second material in a molten state is injected into a mold so that it is combined with the first material to form the middle plate.

7. The method for preparing a middle frame according to any one of claims 1 to 6, characterized in that: The sprayed layer is a metal sprayed layer, and the metal sprayed layer is composed of a plurality of metal particles.

8. The method for preparing a middle frame according to claim 1, characterized in that: The first material and the second material are both metal materials.

9. The method for preparing the middle frame according to claim 1, characterized in that: The first material is a non-metal material, and the second material is a metal material.

10. The method for preparing the middle frame according to claim 9, characterized in that: The first material is configured as ceramic.

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