Machining process of 3C accessory based on 7-series aluminum alloy

Abstract

The invention provides a machining process of a 3C accessory based on 7-series aluminum alloy, the 7-series aluminum alloy comprises, by weight, 1.5-2% of magnesium, 4-6% of zinc, 0.01-0.1% of copper, 0.03-0.08% of silicon, 0.02-0.03% of titanium and the balance aluminum, the 7-series aluminum alloy is prepared into a liquid state or a semi-solid state and then transferred into a charging barrel, and the charging barrel is in butt joint with a mold; the 7-series aluminum alloy in the charging barrel is fed into the mold for mold filling; a movable mold of the mold is provided with at least one extrusion pin, the extrusion pin penetrates into a cavity of the mold, the extrusion pin is in a retreating state during mold filling, the extrusion pin is inserted into the cavity after mold filling is completed, and the extrusion pin is taken out for 8-13 seconds. According to the 3C accessory, in the anodic oxidation process, a uniform and dense oxidation layer with the proper thickness can be formed, and the 3C accessory has the good corrosion resistance, the outer surface with the uniform color and the high tensile strength.

Description

Technical Field

[0001] The invention relates to the field of 3C accessories processing, and in particular to a processing technology of 3C accessories based on 7 series aluminum alloy. Background Art

[0002] With the development of the demand for thin and light 3C accessories, the requirements for frames are gradually increasing. Aluminum alloy frames are characterized by thinness and high strength, and are adopted by more and more manufacturers. At present, the 6-series aluminum alloy has a relatively high degree of commercialization. The 6-series aluminum alloy has magnesium and silicon as the main added elements and has good corrosion resistance. With the further pursuit of manufacturers for thin and light mobile phones, the strength of the 6-series aluminum alloy is difficult to meet the requirements. The 7-series aluminum alloy has magnesium, zinc and copper as the main added elements, has super high hardness, and is widely used in the aviation field. The application of the 7-series aluminum alloy to 3C accessories can meet the demand for higher hardness of 3C accessories. However, the surface quality of the 7-series aluminum alloy is poor, and it is easy to produce element segregation. Therefore, it is difficult to obtain a better anodizing effect by directly applying the 7-series aluminum alloy to 3C accessories, and the oxide layer is easy to corrode and fall off.

[0003] Therefore, it is necessary to provide a processing technology for 3C accessories based on 7 series aluminum alloy. Summary of the invention

[0004] The first aspect of the present invention provides a processing technology for 3C accessories based on 7 series aluminum alloy, wherein the 7 series aluminum alloy, in terms of weight fraction, contains 1.5-2% magnesium, 4-6% zinc, 0.01-0.1% copper, 0.03-0.08% silicon, 0.02-0.03% titanium and the remainder aluminum. The 7 series aluminum alloy is prepared into a liquid or semi-solid state and then transferred to a barrel, and the barrel is docked with a mold; the 7 series aluminum alloy in the barrel is sent into the mold for filling; the movable mold of the mold is provided with at least one extrusion pin, the extrusion pin penetrates into the mold cavity of the mold, the extrusion pin is in a retracted state during filling, and the extrusion pin is inserted into the mold cavity with a delay of 1-3S after the filling is completed, and the removal time of the extrusion pin is 8-13S.

[0005] Beneficial effects: This solution reduces the content of copper and silicon. Copper dissolves much faster than aluminum during the anodizing process, which will cause the oxide film to be too thin and affect the color of the oxide layer. Silicon does not react during the anodizing process, thereby preventing the oxidation of aluminum and causing uneven thickness of the oxide layer. The above problems can be avoided by reducing the content of copper and silicon; by reducing the zinc content and using titanium as a refiner, the formation of coarsened MgZn2 can be reduced, the risk of stress corrosion cracking can be reduced, and the fluidity of the melt can be improved; however, reducing the content of zinc, copper and silicon will further reduce the fluidity of the 7 series aluminum alloy. Therefore, this solution combines indirect extrusion and local extrusion processes to reduce the shrinkage problem caused by reduced fluidity. Therefore, the 3C accessories of this solution can form a uniform, dense and appropriately thick oxide layer during the anodizing process, have better corrosion resistance and a uniformly colored outer surface and have strong tensile strength.

[0006] Furthermore, 4.5-5.5% zinc is included. If the zinc content is too low, it will affect the formation of the MgZn2 strengthening phase, resulting in too low tensile strength of the 3C accessories; if the zinc content is too high, it will promote the coarsening of the MgZn2 strengthening phase. The combination of the above zinc content and the preparation process can produce 3C accessories that take into account both tensile strength and corrosion resistance.

[0007] Furthermore, it contains 0.02~0.06% copper. If the copper content is too low, it cannot play an alloying role to improve the strength of 3C accessories; if the copper content is too high, it will affect the oxide layer, and ultimately affect the surface quality and corrosion resistance.

[0008] Furthermore, it contains 1.5% magnesium, 4.5% zinc, 0.03% copper, 0.03% silicon, 0.02% titanium and the balance aluminum. The above-mentioned 7 series aluminum alloy combined with the preparation process can obtain the best corrosion resistance and tensile strength.

[0009] Furthermore, the filling speed is 180-220 mm / s. In this process, the fluidity of the 7 series aluminum alloy is poor, and a higher filling speed is required to avoid defects such as shrinkage and pores.

[0010] Furthermore, the filling pressure is 140-200MPa, and the holding time is 10-30S. If the holding pressure is too low, it is difficult for the material to overcome the flow resistance and fully fill the mold cavity during the holding stage, resulting in more shrinkage holes and other defects; if the holding pressure is too high, it may cause overflow. If the holding time is too short, the casting temperature is too high, which will lead to insufficient shrinkage compensation; if the holding time is too long, it will affect production efficiency.

[0011] Furthermore, the extrusion depth is 2-6 mm. If the extrusion depth is too small, the metal liquid added is insufficient and it is difficult to achieve the shrinkage compensation effect; if the extrusion depth is too large, it is easy to cause damage to the casting.

[0012] Furthermore, the extrusion pin is arranged on the plane or bottom hole of the thick wall of the 3C accessory. The thick wall can allow a greater extrusion depth and achieve a better shrinkage compensation effect.

[0013] A second aspect of the present invention provides a 3C accessory, characterized in that it is prepared using the above-mentioned 3C accessory processing technology.

[0014] The 3C accessories obtained by the above preparation method have excellent anodizing effect, corrosion resistance and tensile strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the 3C accessories of Example 1.

[0016] Figure 2 This is a schematic diagram of the 3C accessories of Comparative Example 1.

[0017] Figure 3 It is a comparison diagram of the 3C accessories of Example 1 (top) and Comparative Example 1 (bottom). DETAILED DESCRIPTION

[0018] For ease of understanding of the application, the application will be described more fully below. The application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the application more thorough and comprehensive.

[0019] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of the present application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0021] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0022] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0023] The percentage contents involved in this application, unless otherwise specified, refer to mass percentage for solid-liquid mixing and solid-solid mixing, and refer to volume percentage for liquid-liquid mixing.

[0024] The percentage concentrations mentioned in this application, unless otherwise specified, refer to the final concentration, which refers to the percentage of the added component in the system after the addition of the component.

[0025] The temperature parameters in this application, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range of instrument control.

[0026] The "particles" mentioned in this application, or materials with a defined particle size distribution, are not necessarily spherical in shape, but may be irregular, primary particles or secondary particles. The particle size of irregular particles is the average of their maximum diameter and minimum diameter.

[0027] Example 1: This example provides a processing technology for 3C accessories (all examples and comparative examples are mobile phone frames) based on 7 series aluminum alloy, which is prepared by optimizing the 7 series aluminum alloy formula and combining indirect extrusion and local extrusion, and includes the following steps: Preparation of 10 kg of 7 series aluminum alloy melt: by weight fraction, 1.5% magnesium, 6% zinc, 0.1% copper, 0.08% silicon, 0.03% titanium and the balance aluminum are weighed, mixed, heated, degassed and deslaged to form an aluminum alloy melt, and kept warm at 680°C.

[0028] Indirect extrusion and partial extrusion: install the extrusion pin at the bottom hole of the thick wall of the casting on the mold and put it in the retracted state, transfer the 7 series aluminum alloy melt into the barrel, dock the barrel with the mold to prepare for injection, and preheat the barrel to 250℃. Inject the melt into the mold at a speed of 220mm / s, and maintain the pressure at 200MPa for 15S after filling. Activate the extrusion pin 3S after the start of filling, the extrusion depth is 6mm, and take it out after 13S. After the pressure holding time is over, open the mold and take out the casting.

[0029] T6 heat treatment: solution treatment at 550°C for 1 hour, aging treatment at 185°C for 10 hours to obtain 3C castings.

[0030] Anodizing: CNC machining and anodizing of the casting surface.

[0031] Embodiment 2: This embodiment provides a processing technology for 3C accessories based on 7 series aluminum alloy, which is prepared by optimizing the 7 series aluminum alloy formula and combining indirect extrusion and local extrusion, and comprises the following steps: Preparation of 10 kg of 7 series aluminum alloy melt: by weight, 2% magnesium, 4% zinc, 0.1% copper, 0.03% silicon, 0.02% titanium and the balance aluminum are weighed, mixed, heated, degassed and deslaged to form an aluminum alloy melt, and kept warm at 680°C.

[0032] Indirect extrusion and partial extrusion: install the extrusion pin at the bottom hole of the thick wall of the casting on the mold and put it in the retracted state, transfer the 7 series aluminum alloy melt into the barrel, dock the barrel with the mold to prepare for injection, and preheat the barrel to 250℃. Inject the melt into the mold at a speed of 220mm / s, and maintain the pressure at 200MPa for 15S after filling. Activate the extrusion pin 3S after the start of filling, the extrusion depth is 6mm, and take it out after 13S. After the pressure holding time is over, open the mold and take out the casting.

[0033] T6 heat treatment: solution treatment at 550°C for 1 hour, aging treatment at 185°C for 10 hours to obtain 3C castings.

[0034] Anodizing: CNC machining and anodizing of the casting surface.

[0035] Embodiment 3: This embodiment provides a processing technology for 3C accessories based on 7 series aluminum alloy, which is prepared by optimizing the 7 series aluminum alloy formula and combining indirect extrusion and local extrusion, and comprises the following steps: Preparation of 10 kg of 7 series aluminum alloy melt: by weight, 1.5% magnesium, 5.5% zinc, 0.1% copper, 0.08% silicon, 0.03% titanium and the balance aluminum are weighed, mixed, heated, degassed and deslaged to form an aluminum alloy melt, and kept warm at 680°C.

[0036] Indirect extrusion and partial extrusion: install the extrusion pin at the bottom hole of the thick wall of the casting on the mold and put it in the retracted state, transfer the 7 series aluminum alloy melt into the barrel, dock the barrel with the mold to prepare for injection, and preheat the barrel to 250℃. Inject the melt into the mold at a speed of 220mm / s, and maintain the pressure at 200MPa for 15S after filling. Activate the extrusion pin 3S after the start of filling, the extrusion depth is 6mm, and take it out after 13S. After the pressure holding time is over, open the mold and take out the casting.

[0037] T6 heat treatment: solution treatment at 550°C for 1 hour, aging treatment at 185°C for 10 hours to obtain 3C castings.

[0038] Anodizing: CNC machining and anodizing of the casting surface.

[0039] Embodiment 4: This embodiment provides a processing technology for 3C accessories based on 7 series aluminum alloy, which is prepared by optimizing the 7 series aluminum alloy formula and combining indirect extrusion and local extrusion, and comprises the following steps: Preparation of 10 kg of 7 series aluminum alloy melt: In terms of weight fraction, 1.5% magnesium, 6% zinc, 0.06% copper, 0.08% silicon, 0.03% titanium and the balance aluminum are weighed, mixed, heated, degassed and deslaged to form an aluminum alloy melt, and kept warm at 680°C.

[0040] Indirect extrusion and partial extrusion: install the extrusion pin at the bottom hole of the thick wall of the casting on the mold and put it in the retracted state, transfer the 7 series aluminum alloy melt into the barrel, dock the barrel with the mold to prepare for injection, and preheat the barrel to 250℃. Inject the melt into the mold at a speed of 220mm / s, and maintain the pressure at 200MPa for 15S after filling. Activate the extrusion pin 3S after the start of filling, the extrusion depth is 6mm, and take it out after 13S. After the pressure holding time is over, open the mold and take out the casting.

[0041] T6 heat treatment: solution treatment at 550°C for 1 hour, aging treatment at 185°C for 10 hours to obtain 3C castings.

[0042] Anodizing: CNC machining and anodizing of the casting surface.

[0043] Embodiment 5: This embodiment provides a processing technology for 3C accessories based on 7 series aluminum alloy, which is prepared by optimizing the 7 series aluminum alloy formula and combining indirect extrusion and local extrusion, and comprises the following steps: Preparation of 10 kg of 7 series aluminum alloy melt: In terms of weight fraction, 1.5% magnesium, 4.5% zinc, 0.03% copper, 0.03% silicon, 0.02% titanium and the balance aluminum are weighed, mixed, heated, degassed and deslaged to form an aluminum alloy melt, and kept warm at 680°C.

[0044] Indirect extrusion and partial extrusion: install the extrusion pin at the bottom hole of the thick wall of the casting on the mold and put it in the retracted state, transfer the 7 series aluminum alloy melt into the barrel, dock the barrel with the mold to prepare for injection, and preheat the barrel to 250℃. Inject the melt into the mold at a speed of 220mm / s, and maintain the pressure at 200MPa for 15S after filling. Activate the extrusion pin 3S after the start of filling, the extrusion depth is 6mm, and take it out after 13S. After the pressure holding time is over, open the mold and take out the casting.

[0045] T6 heat treatment: solution treatment at 550°C for 1 hour, aging treatment at 185°C for 10 hours to obtain 3C castings.

[0046] Anodizing: CNC machining and anodizing of the casting surface.

[0047] Embodiment 6: This embodiment provides a processing technology for 3C accessories based on 7 series aluminum alloy, which is prepared by optimizing the 7 series aluminum alloy formula and combining indirect extrusion and local extrusion, and comprises the following steps: Preparation of 10 kg of 7 series aluminum alloy melt: by weight fraction, 1.5% magnesium, 6% zinc, 0.1% copper, 0.08% silicon, 0.03% titanium and the balance aluminum are weighed, mixed, heated, degassed and deslaged to form an aluminum alloy melt, and kept warm at 650°C.

[0048] Indirect extrusion and partial extrusion: install the extrusion pin on the plane corresponding to the thick wall of the casting on the mold and put it in the retracted state, transfer the 7 series aluminum alloy melt into the barrel, dock the barrel with the mold to prepare for injection, and preheat the barrel to 250℃. Inject the melt into the mold at a speed of 180mm / s, and hold the pressure at 140MPa for 30S after filling. Activate the extrusion pin 3S after the start of filling, the extrusion depth is 6mm, and take it out after 13S. After the holding time is over, open the mold and take out the casting.

[0049] T6 heat treatment: solution treatment at 550°C for 1 hour, aging treatment at 185°C for 10 hours to obtain 3C castings.

[0050] Anodizing: CNC machining and anodizing of the casting surface.

[0051] Embodiment 7: This embodiment provides a processing technology for 3C accessories based on 7 series aluminum alloy, which is prepared by optimizing the 7 series aluminum alloy formula and combining indirect extrusion and local extrusion, and comprises the following steps: Prepare 10 kg of 7 series aluminum alloy melt: by weight, weigh 1.5% magnesium, 4.5% zinc, 0.03% copper, 0.03% silicon, 0.02% titanium and the remainder aluminum, mix them, heat them, degas and deslag them to form an aluminum alloy melt, cool them to obtain a melt with a solid phase fraction of 30%, and keep them warm.

[0052] Indirect extrusion and partial extrusion: install the extrusion pin at the bottom hole of the thick wall of the casting on the mold and put it in the retracted state, transfer the 7 series aluminum alloy melt into the barrel, dock the barrel with the mold to prepare for injection, and preheat the barrel to 250℃. Inject the melt into the mold at a speed of 220mm / s, and maintain the pressure at 200MPa for 15S after filling. Activate the extrusion pin 1S after the start of filling, the extrusion depth is 2mm, and take it out after 8S. After the pressure holding time is over, open the mold and take out the casting.

[0053] T6 heat treatment: solution treatment at 550°C for 1 hour, aging treatment at 185°C for 10 hours to obtain 3C castings.

[0054] Anodizing: CNC machining and anodizing of the casting surface.

[0055] Comparative Example 1: This comparative example provides a processing technology for 3C accessories, comprising the following steps: Preparation of 10 kg of 7 series aluminum alloy melt: by weight fraction, 1.5% magnesium, 6% zinc, 0.1% copper, 0.08% silicon, 0.03% titanium and the balance aluminum are weighed, mixed, heated, degassed and deslaged to form an aluminum alloy melt, and kept warm at 680°C.

[0056] Indirect extrusion: Install the extrusion pin at the bottom hole of the thick wall of the casting on the mold and put it in the retracted state, transfer the 7 series aluminum alloy melt into the barrel, dock the barrel with the mold to prepare for injection, and preheat the barrel to 250℃. Inject the melt into the mold at a speed of 220mm / s, and hold the pressure at 200MPa for 15S after the filling is completed. After the holding time is over, open the mold and take out the casting.

[0057] T6 heat treatment: solution treatment at 550°C for 1 hour, aging treatment at 185°C for 10 hours to obtain 3C castings.

[0058] Anodizing: CNC machining and anodizing of the casting surface.

[0059] Comparative Example 2: This comparative example provides a processing technology for 3C accessories, comprising the following steps: Preparation of 10 kg of 7 series aluminum alloy melt: by weight, 2% magnesium, 8% zinc, 1% copper, 0.08% silicon, 0.03% titanium and the balance aluminum are weighed, mixed, heated, degassed and deslaged to form an aluminum alloy melt, and kept warm at 680°C.

[0060] Indirect extrusion: Install the extrusion pin at the bottom hole of the thick wall of the casting on the mold and put it in the retracted state, transfer the 7 series aluminum alloy melt into the barrel, dock the barrel with the mold to prepare for injection, and preheat the barrel to 250℃. Inject the melt into the mold at a speed of 220mm / s, and hold the pressure at 200MPa for 15S after the filling is completed. After the holding time is over, open the mold and take out the casting.

[0061] T6 heat treatment: solution treatment at 550°C for 1 hour, aging treatment at 185°C for 10 hours to obtain 3C castings.

[0062] Anodizing: CNC machining and anodizing of the casting surface.

[0063] Comparative Example 3: This comparative example provides a processing technology for 3C accessories, comprising the following steps: Preparation of 10 kg of 7 series aluminum alloy melt: by weight, 2% magnesium, 8% zinc, 1% copper, 0.08% silicon, 0.03% titanium and the balance aluminum are weighed, mixed, heated, degassed and deslaged to form an aluminum alloy melt, and kept warm at 680°C.

[0064] Indirect extrusion and partial extrusion: install the extrusion pin at the bottom hole of the thick wall of the casting on the mold and put it in the retracted state, transfer the 7 series aluminum alloy melt into the barrel, dock the barrel with the mold to prepare for injection, and preheat the barrel to 250℃. Inject the melt into the mold at a speed of 220mm / s, and maintain the pressure at 200MPa for 15S after filling. Activate the extrusion pin 3S after the start of filling, the extrusion depth is 6mm, and take it out after 13S. After the pressure holding time is over, open the mold and take out the casting.

[0065] T6 heat treatment: solution treatment at 550°C for 1 hour, aging treatment at 185°C for 10 hours to obtain 3C castings.

[0066] Anodizing: CNC machining and anodizing of the casting surface.

[0067] The 3C accessories obtained in Examples 1-7 and Comparative Examples 1-3 were tested, and the tensile strength was detected by the method according to ASTM-B557 standard, the anode surface effect was tested by visual observation, and the corrosion experiment was carried out by the method of GB / T10125, and the following Table 1 was obtained.

[0068] Table 1 3C accessories test results

[0069] According to the data in Table 1, the tensile strength, surface quality and corrosion resistance of Examples 1-7 are better than those of Comparative Examples 1-3. This is because the present solution combines the optimized 7-series aluminum alloy formula with indirect extrusion and local extrusion processes. The 7-series aluminum alloy formula reduces the copper and silicon content, and can form a uniform oxide layer to obtain good corrosion resistance and color uniformity after oxidation. By reducing the zinc content and using titanium as a refiner, the formation of coarsened MgZn2 can be reduced, the risk of stress corrosion cracking can be reduced, and the fluidity of the melt can be improved. The indirect extrusion process and the local extrusion process reverse the defects such as shrinkage cavities and shrinkage cavities caused by poor melt fluidity during the die-casting process due to formula optimization. In this way, the 3C accessories of the present solution can form a uniform, dense and appropriately thick oxide layer during the anodizing process, and have better corrosion resistance and a uniformly colored outer surface and strong tensile strength. Figure 1-3 As shown, the 3C accessories of Example 1 have no obvious pores, the anode has no discoloration and no flow marks, while the 3C accessories of Comparative Example 1 have obvious flow marks and pores. Comparative Example 1 did not use local extrusion to compensate for shrinkage, because the melt fluidity of this formula is poor, and the casting has more shrinkage cavities, which affects its tensile strength and surface quality. Comparative Example 2 used a conventional aluminum alloy with high magnesium, zinc and copper content. Compared with Comparative Example 1, its surface oxide layer has poor quality and poor corrosion resistance. Comparative Example 3 used a conventional aluminum alloy with high magnesium, zinc and copper content combined with indirect extrusion and local extrusion processes. It has fewer pores than Comparative Example 2, but its anodizing quality and corrosion resistance are not significantly improved.

[0070] Example 3 uses the preferred zinc content, which has better tensile strength. Example 4 uses the preferred copper content, and its oxide layer is less likely to fall off. Example 5 uses the most preferred 7-series aluminum alloy formula, and its tensile strength, surface quality and corrosion resistance are improved. Example 7 uses the most preferred 7-series aluminum alloy formula, and further makes the aluminum alloy melt into a semi-solid melt with a solid phase fraction of 30%, and its tensile strength is further improved relative to Example 5.

[0071] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A processing technology for 3C accessories based on 7 series aluminum alloy, characterized in that: The 7 series aluminum alloy, measured by weight, contains 1.5-2% magnesium, 4-6% zinc, 0.01-0.1% copper, 0.03-0.08% silicon, 0.02-0.03% titanium and the balance aluminum. The 7 series aluminum alloy is prepared into a liquid or semi-solid state and then transferred to a barrel, and the barrel is docked with a mold; the 7 series aluminum alloy in the barrel is sent into the mold for filling; the movable mold of the mold is provided with at least one extrusion pin, and the extrusion pin penetrates into the mold cavity of the mold. The extrusion pin is in a retracted state during filling, and the extrusion pin is inserted into the mold cavity with a delay of 1-3S after the filling is completed, and the removal time of the extrusion pin is 8-13S.

2. The processing technology according to claim 1, characterized in that: The 7 series aluminum alloy contains 4.5-5.5% zinc by weight.

3. The processing technology according to claim 1, characterized in that: The 7 series aluminum alloy contains 0.02-0.06% copper by weight.

4. The processing technology according to claim 1, characterized in that: The 7 series aluminum alloy contains, by weight, 1.5% magnesium, 4.5% zinc, 0.03% copper, 0.03% silicon, 0.02% titanium and the balance aluminum.

5. The processing technology according to claim 1, characterized in that: The filling speed is 180-220 mm / s.

6. The processing technology according to claim 1, characterized in that: After the 7 series aluminum alloy is prepared into a liquid or semi-solid state, the temperature of the 7 series aluminum alloy is 650-700°C.

7. The processing technology according to claim 1, characterized in that: The filling pressure is 140-200 MPa, and the holding time is 10-30S.

8. The processing technology according to claim 1, characterized in that: The extrusion depth of the extrusion pin is 2-6 mm.

9. The processing technology according to claim 1, characterized in that: The extrusion pin is arranged on the thick-walled plane or bottom hole of the 3C accessory.

10. A 3C accessory, characterized in that: It is prepared using the processing technology of the 3C accessories described in any one of claims 1-9.

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