A kind of oxidizable coloring die-casting aluminum alloy material and its process for producing mobile phone middle plate and frame

Abstract

The present invention provides an oxidizable color die-cast aluminum alloy material and a process for producing a mobile phone middle plate and frame, and relates to the field of aluminum alloy design technology. The oxidizable color die-cast aluminum alloy material is composed of elements such as Si, Fe, Mg, Mn, Zn, Cu, Zr, Ti, Ca, and mixed rare earths, and the mixed rare earths are obtained by mixing Ce and La, and the mass ratio of Ce to La is 1.5 to 1.8, and the die-cast aluminum alloy material is used to produce a mobile phone middle plate and frame, which is an integrated die-cast mobile phone middle plate and frame or is die-casted with a 6013 aluminum profile to form a mobile phone middle plate and frame. The present invention overcomes the shortcomings of the prior art, and the die-cast aluminum alloy material can be used to produce a middle plate and frame together with a 6013 aluminum alloy sheet. While improving the mechanical properties of the die-cast aluminum alloy material, it is convenient for subsequent production and processing, and reduces the production cost of the mobile phone middle plate and frame.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy design, and in particular to an oxidizable and colored die-cast aluminum alloy material and a process for producing a mobile phone mid-plate and frame thereof. Background Art

[0002] The frame and middle plate of a mobile phone are two important parts of the mobile phone structure, which generally play a good supporting and protective role. Most of the mobile phone frames on the market are made of aluminum alloy, and the high-quality frames and middle plates are generally made of 6013 aluminum alloy materials. The processing methods of mobile phone frames and middle plates are mainly: using 6013 aluminum alloy plates for heat treatment and then CNC processing. This type of processing method generally has a large processing volume, large metal loss, slow efficiency and high cost; the other is to use conventional die-cast aluminum alloy for die-casting, but conventional die-cast aluminum alloy can generally only be made in black. If you want to make other colors, you have to use PVD technology, which is more expensive.

[0003] In addition to the above two methods, in order to save costs, the beer-in-place process is also a common method of use. The beer-in-place process is a mechanical processing method that uses sleeves and beer heads to cut raw materials into parts of the required shape and size. The workpiece is placed on the machine tool, and the sleeve and beer head are rolled on the surface of the workpiece through rotation and cutting force to complete the processing of the part. The beer-in-place process can be used to process various metal parts, and is also suitable for certain non-metallic materials. Based on this, the frame and the middle plate can be processed separately. Using different materials for beer-in-place production saves certain costs, but in actual production, the beer-in-place process is prone to vibration and noise, which has certain damage to the equipment and workpiece; there may be problems with the surface quality after processing, and secondary processing is required; the processing process has high technical requirements and operation level requirements for the processing workers, and the required equipment cost is also high. In addition, if two metals are used for processing, subsequent heat treatment cannot be performed, and cracks are likely to appear at the connection. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides an oxidizable and colored die-cast aluminum alloy material and a process for using the same in the production of a mobile phone middle plate and frame. The die-cast aluminum alloy material can be used together with a 6013 aluminum alloy sheet to produce a middle plate and frame. While improving the mechanical properties of the die-cast aluminum alloy material, it facilitates subsequent production and processing and reduces the production cost of the mobile phone middle plate and frame.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented through the following technical solutions:

[0006] Disclosed is an oxidizable coloring die-casting aluminum alloy material, which is composed of the following substances in percentage by mass: Si: 0.4%-0.7%, Fe: 0.5%-0.75%, Mg: 0.4%-0.6%, Mn: 1.9%-2.4%, Zn: 2.9%-3.5%, Cu: 0.25%-1.0%, Zr: 0.2%-0.35%, Ti: 0.05%-0.1%, Ca: 0.005%-0.01%, mixed rare earth: 0.1%-0.2%, and the remainder is Al and unavoidable impurities; the mixed rare earth is obtained by mixing Ce and La, and the mass ratio of Ce to La is 1.5-1.8, and the weight percentage content of Fe≥Si, Mg+Si≥1%.

[0007] Preferably, the mass percentage of the unavoidable impurities is less than 0.25%.

[0008] The above die-cast aluminum alloy material is used to produce mobile phone mid-plates and frames.

[0009] The die-cast aluminum alloy material is used to produce the mobile phone middle plate and frame, which is either an integrated die-cast mobile phone middle plate and frame or die-casted with 6013 aluminum profile to form the mobile phone middle plate and frame. The process of die-casting with 6013 aluminum profile to form the mobile phone middle plate and frame includes the following steps:

[0010] S1. Use L-shaped aluminum profile as frame material, and perform extrusion shaping to obtain a frame body for standby use;

[0011] S2, after the frame body is baked and expanded, it is implanted into the die-casting mold of the middle plate, and then the alloy liquid of the die-casting aluminum alloy material is injected into the mold for die-casting, and the alloy liquid injection temperature during die-casting is 740-760° C., and the mold temperature is ≥180° C., and the blank of the middle plate and the frame is obtained for standby;

[0012] S3. After artificial aging treatment, the above-mentioned blank is subjected to CNC processing of the antenna part and the internal structure, and then nano injection molding and anodizing coloring are performed.

[0013] Preferably, the L-shaped aluminum profile in step S1 is made of 6013 aluminum alloy material.

[0014] Preferably, the extrusion shaping method in step S1 is to select two L-shaped aluminum profiles for extrusion and then saw them as required, then use CNC to dig out the inner groove of the L-shaped aluminum profile, and perform laser roughening and etching on the inner side of the L-shaped aluminum profile.

[0015] Preferably, the frame body is baked and expanded at a temperature of 200-300° C. in step S2, and the baking time is ≥10 min.

[0016] Preferably, the temperature of the artificial aging treatment in step S3 is 180° C. and the treatment time is 3 hours.

[0017] The present invention provides an oxidizable coloring die-cast aluminum alloy material and a process for producing a mobile phone mid-plate and frame, which has the following advantages over the prior art:

[0018] (1) Compared with the die-cast aluminum alloy material provided by this unit with application number 202410532786.5, "A die-cast aluminum alloy, its preparation method and anodizing application", the die-cast aluminum alloy material provided by the present invention has adjusted the content of the components, greatly improved the mechanical properties of the alloy material, and can effectively improve the thermal cracking resistance, which is convenient for the subsequent production of mobile phone middle plate and frame with 6013 aluminum alloy, ensuring the stability of product performance. In addition, the cost of directly using CNC to process a mobile phone middle plate and frame using 6013 aluminum alloy material is about RMB 120 per piece, while the cost price of using 6013 aluminum alloy and die-cast aluminum alloy to produce mobile phone middle plate and frame using the process and materials of this application is reduced to about RMB 60 per piece, which greatly reduces the production cost.

[0019] (2) The process of the present application is neither "casing" nor "inserted casting". Inserted casting is a casting that is tightly wrapped by alloy liquid (from the outside to the inside), while the process of the present invention is a casting that is "supported" by die-cast aluminum liquid (from the inside to the outside). During the casting process, the two metals are cast together and cannot be heat treated to avoid the different expansion coefficients of the two metals causing cracks. However, the present application can be artificially aged to increase the mechanical properties and meet the needs of drop tests. In addition, since the frame (6013) and the middle plate materials in the present application are both aluminum alloys that can be anodized and colored, the risk of ordinary aluminum-silicon alloys contaminating the coloring tank liquid is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the surface oxide film of the oxidizable color die-casting aluminum alloy material 1 prepared in Example 1 of the present invention after anodizing;

[0021] Figure 2 Schematic diagram of sampling locations of the middle plate and frame blank 1 in an embodiment of the present invention, wherein the red frame is a specific sampling and testing location;

[0022] Figure 3 Schematic diagram of the metallographic structure of the middle plate of the middle plate and frame blank 1 in the embodiment of the present invention;

[0023] Figure 4 This is a complete schematic diagram of the middle plate and frame blank 1 in an embodiment of the present invention;

[0024] Figure 5 Schematic diagram of thermal cracks in the middle plate and frame blank 2 in the embodiment of the present invention;

[0025] Figure 6 It is a microscopic schematic diagram of the hot crack of the middle plate connecting frame blank 2 in the embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The deslagging agent used below is obtained by mixing NaCl and KCl in a mass ratio of 1.8:2.

[0028] Embodiment 1:

[0029] Preparation of oxidizable coloring die-casting aluminum alloy materials:

[0030] (1) Add pure aluminum ingot into the furnace and heat to 700°C to melt, then add iron additive and aluminum-copper master alloy and heat to 760°C to melt for 8 minutes, then adjust the temperature to 730°C to obtain the first molten metal;

[0031] (2) heating the aluminum-silicon master alloy, the aluminum-manganese master alloy, the aluminum-zirconium master alloy, the aluminum-titanium master alloy, the aluminum-calcium master alloy, the pure zinc ingot, and the pure magnesium ingot to 780° C. and melting them to obtain a second molten metal for later use;

[0032] (3) adding aluminum-lanthanum-cerium master alloy to the first alloy liquid, heating it to 840°C to melt it and keeping it warm, then pouring in the second alloy liquid heated to 880°C, keeping it warm at 730°C to obtain the alloy liquid for use;

[0033] (4) Add 0.6% of the total mass of the alloy liquid to the alloy liquid. Adjust the temperature to 710℃ and refine for 8 minutes. Then remove the slag and detect and adjust the content of each component in the alloy liquid as follows:

[0034] Si: 0.4%, Fe: 0.5%, Mg: 0.6%, Mn: 1.9%, Zn: 2.9%, Cu: 0.25%, Zr: 0.2%, Ti: 0.05%, Ca: 0.005%, Ce: 0.08%, La: 0.05%; the balance is Al and impurities <0.25%.

[0035] DEK oxidation colored die casting aluminum alloy material 1.

[0036] Embodiment 2:

[0037] Preparation of oxidizable coloring die-casting aluminum alloy materials:

[0038] The preparation method is the same as that of Example 1, except that the contents of the components in the alloy liquid are different. The specific contents of the components in the alloy liquid are as follows:

[0039] Si: 0.7%, Fe: 0.75%, Mg: 0.4%, Mn: 2.4%, Zn: 3.5%, Cu: 1.0%, Zr: 0.35%, Ti: 0.1%, Ca: 0.01%, Ce: 0.12%, La: 0.07%, the balance is Al and impurities < 0.25%, to obtain an oxidizable and colored die-cast aluminum alloy material 2.

[0040] Comparative Example 1:

[0041] Preparation of die-casting aluminum alloy materials:

[0042] (1) Add pure aluminum ingots into the furnace and heat to 700°C to melt, then add silver blocks, iron additives, and copper rice and heat to 760°C to melt for 8 minutes, then adjust the temperature to 730°C to obtain the first molten metal;

[0043] (2) heating the aluminum-silicon master alloy, the aluminum-manganese master alloy, the aluminum-zirconium master alloy, the aluminum-titanium master alloy, the pure zinc ingot, and the pure magnesium ingot to 780° C. to melt and obtain a second molten metal for later use;

[0044] (3) adding aluminum-lanthanum-cerium master alloy to the first alloy liquid, heating it to 840°C to melt it and keeping it warm, then pouring in the second alloy liquid heated to 880°C, keeping it warm at 730°C to obtain the alloy liquid for use;

[0045] (4) Add 0.6% of the total mass of the alloy liquid to the alloy liquid. Adjust the temperature to 710℃ and refine for 8 minutes. Then remove the slag and detect and adjust the content of each component in the alloy liquid as follows:

[0046] Si: 0.15%, Fe: 0.2%, Mg: 0.6%, Mn: 1.8%, Zn: 2.8%, Cu: 0.15%, Zr: 0.2%, Ti: 0.1%, Ag: 0.1%, Ce: 0.1%, La: 0.05%, the remainder is aluminum and unavoidable impurities, and the impurity content is ≤0.01%, thereby obtaining a die-casting aluminum alloy material.

[0047] Detection:

[0048] 1. The oxidizable colored die-casting aluminum alloy materials 1-2 prepared in the above-mentioned examples 1-2 and the die-casting aluminum alloy materials prepared in comparative example 3 were directly die-casted (the mold temperature was kept at 180°C, and the temperature of the aluminum alloy liquid metal was 750°C during injection). The die-cast materials were directly tested for mechanical properties and hardness, and the die-cast materials of each group were artificially aged at 180°C for 3 hours before being tested for mechanical properties and hardness;

[0049] The test is based on the tensile strength, yield strength and elongation of aluminum alloy castings tested in accordance with GB / T 228.1-2010 Tensile test of metallic materials Part 1: Test method at room temperature (tensile speed: 2 mm / min). According to the standard: GB / T231.1-2009, 3 points are tested and the average value is taken to obtain the Vickers hardness of each group of materials. The specific results are shown in Table 1 below:

[0050] Table 1

[0051]

[0052] It can be seen from the above table that compared with Comparative Example 1, the die-cast aluminum alloy prepared in Example 1-2 has higher hardness and mechanical properties, and the mechanical properties of the die-cast aluminum alloy of Example 1-2 after artificial aging treatment are improved.

[0053] 2. The oxidizable color die-casting aluminum alloy material 1 prepared in the above embodiment 1 is subjected to anodizing treatment. The specific anodizing treatment method is as follows:

[0054] First, the oxidizable coloring die-cast aluminum alloy material 1 was processed by CNC to remove the 0.2 mm chill layer on the alloy surface, and then sandblasted for 3 minutes using 170 mesh zirconium sand;

[0055] According to HB / Z 118-1987 "Chromic Acid Anodizing Process for Aluminum and Aluminum Alloys", each group of aluminum alloy materials was anodized with chromic acid:

[0056] The process flow is: upper hanger → degreasing → water washing → deoxidation → water washing → polishing → water washing → chromic acid anodizing → water washing → deionized water washing → sealing → drying → lower hanging.

[0057] The process conditions for oil removal are: NaOH 28 g / L, Na2CO3 30 g / L, temperature 40 ~ 55℃, time 15 min.

[0058] The process conditions for light emission are: 40% nitric acid (volume fraction), time 30 s.

[0059] The process conditions of anodization were: CrO3 45 g / L, temperature (35 ± 2) ℃, voltage (40 ± 1) V, and time 30 min.

[0060] The specific coloring of the oxide film after anodizing is as follows Figure 1 As shown, the surface oxide film is uniformly colored as a whole, and the surface of the oxide film is smooth and continuous without color difference.

[0061] 3. Production of mobile phone middle plate and frame:

[0062] 3.1. Use 6013 aluminum alloy material as the frame, and use the oxidizable coloring die-casting aluminum alloy material 1 prepared in Example 1 as the middle plate:

[0063] Extruding L-shaped aluminum profile (brand: 6013, two L-shaped, assembled into a rectangular frame) → Sawing → CNC digging out the inner groove of the L-shaped aluminum profile → Laser roughening the inner side of the L-shaped aluminum profile → Etching the inner side of the L-shaped aluminum profile (producing pits or grooves to allow the die-cast aluminum liquid to solidify and then rivet the frame) → Baking the L-shaped aluminum profile (250℃, baking for 15min, allowing the profile to expand and die-casting safety requirements) → Implanting two baked L-shaped aluminum profiles in the die-casting mold → Controlling the mold temperature at 200℃, injecting oxidizable and colored die-casting aluminum alloy material 1 metal liquid (750℃) to die-cast the mobile phone middle plate and frame → Artificial aging (180℃, 3h) → CNC processing (antenna part and internal structure);

[0064] Obtain the middle plate and frame blank 1.

[0065] 3.2. Use 6013 aluminum alloy material as the frame, and use the die-cast aluminum alloy material prepared in Comparative Example 1 as the middle plate:

[0066] Extruding L-shaped aluminum profile (brand: 6013, two L-shaped, assembled into a rectangular frame) → Sawing → CNC digging out the inner groove of the L-shaped aluminum profile → Laser roughening the inner side of the L-shaped aluminum profile → Etching the inner side of the L-shaped aluminum profile (producing pits or grooves to allow the die-cast aluminum liquid to solidify and then rivet the frame) → Baking the L-shaped aluminum profile (250℃, baking for 15min, to allow the profile to expand and die-casting safety requirements) → Implanting two baked L-shaped aluminum profiles in the die-casting mold → Controlling the mold temperature at 200℃, injecting die-cast aluminum alloy material molten metal (750℃) to die-cast the mobile phone middle plate and frame → Artificial aging (180℃, 3h) → CNC processing (antenna part and internal structure);

[0067] Obtain the middle plate and frame blank 2.

[0068] 3.3. Control the thickness of the middle plate in the middle plate and frame blank 1-2 to be 1.6 mm, cut the middle plate part of the middle plate and frame blank 1 for metallographic structure observation, and refer to the sampling position Figure 2 , the specific results are as follows Figure 3 As shown;

[0069] 3.4. Observe the apparent structure of the middle plate and frame blanks 1-2. The structure of the middle plate and frame blank 1 is complete (e.g. Figure 4 As shown in the figure), the middle plate connecting frame blank 2 has thermal cracks (as shown in the figure Figure 5 as shown); and metallographic examination of the cracks (such as Figure 6 The typical thermal cracking characteristics.

[0070] In summary, the use of oxidizable and colored die-cast aluminum alloy material 1 as the middle plate and 6013 aluminum alloy material as the frame to prepare the mobile phone middle plate and frame through the above preparation method can effectively prevent thermal cracking.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An oxidizable and colored die-cast aluminum alloy material, characterized in that: The aluminum alloy material is composed of the following substances in mass percentage: Si: 0.4% to 0.7%, Fe: 0.5% to 0.75%, Mg: 0.4% to 0.6%, Mn: 1.9% to 2.4%, Zn: 2.9% to 3.5%, Cu: 0.25% to 1.0%, Zr: 0.2% to 0.35%, Ti: 0.05% to 0.1%, Ca: 0.005% to 0.01%, mixed rare earth: 0.1% to 0.2%, and the balance is Al and unavoidable impurities; The mixed rare earth is obtained by mixing Ce and La, and the mass ratio of Ce to La is 1.5-1.8, and the weight percentage content of Fe≥Si, Mg+Si≥1%.

2. The die-cast aluminum alloy material according to claim 1, characterized in that: The mass percentage of the unavoidable impurities is less than 0.25%.

3. A die-cast aluminum alloy material as described in any one of claims 1-2 is used to produce a mobile phone mid-plate and frame.

4. A process for producing a mobile phone middle plate and frame by die-casting aluminum alloy material as claimed in any one of claims 1-2, characterized in that: The process is to die-cast aluminum alloy material and 6013 aluminum profile together to form a mobile phone middle plate and frame, and the specific process includes the following steps: S1. Using L-shaped aluminum profiles made of 6013 aluminum alloy as frame materials, and performing extrusion shaping to obtain a frame body for standby use; S2, after the frame body is baked and expanded, it is implanted into the die-casting mold of the middle plate, and then the alloy liquid of the die-casting aluminum alloy material is injected into the mold for die-casting, and the alloy liquid injection temperature during die-casting is 740-760°C, and the mold temperature is ≥180°C, and the blank of the middle plate and the frame is obtained for standby; and the temperature of the frame body for baking and expansion is 200-300°C, and the baking time is ≥10min; S3. After artificial aging treatment is performed on the above-mentioned blank, the antenna part and the internal structure are processed by CNC, and then nano injection molding and anodizing coloring are performed.

5. The process according to claim 4, characterized in that: The extrusion shaping method in step S1 is to select two L-shaped aluminum profiles for extrusion and then saw them as required, then use CNC to dig out the inner groove of the L-shaped aluminum profile, and perform laser roughening and etching on the inner side of the L-shaped aluminum profile.

6. The process according to claim 4, characterized in that: The temperature of the artificial aging treatment in step S3 is 180° C. and the treatment time is 3 hours.

7. A process for producing a mobile phone middle plate and frame by die-casting aluminum alloy material according to any one of claims 1-2, characterized in that: The process is to integrally die-cast the mobile phone middle plate and frame with die-cast aluminum alloy material.

Images