阅读说明：本技术 一种高强度手机中框铝合金型材的加工工艺 (Processing technology of high-strength aluminum alloy section for middle frame of mobile phone ) 是由 周晶哲 梁豪辉 刘才兴 于 2020-07-22 设计创作，主要内容包括：本发明公开一种高强度手机中框铝合金型材的加工工艺,包括以下步骤：1)制备铝合金铸锭,按照如下重量份数比配制铝合金原料：Si 0.74~0.77%,Fe≤0.11%,Cu 0.63~0.66%,Mn 0.10~0.12%,Mg 0.96~0.99%,Zn≤0.03%,Ti 0.004~0.008%,单个杂质≤0.01%,杂质合计≤0.05%,余量为Al；2)将铸造后的铝合金铸锭在520-530℃下、555-565℃下分别进行均质；3)表面刷棒或剥皮处理；4)对刷棒或剥皮好的铝合金铸锭进行加热,温度为555~570℃；然后放入挤压机的盛锭筒中进行挤压,挤出速度为5-10m/min；5)挤压型材产品冷却后进行矫正,矫正量0.3-0.8%；6)人工时效处理。本发明制得的铝型材在CNC加工机械抛光氧化后能获得良好的表面效果,光泽度高、表面通透,完全满足手机中框产品的终端要求。(The invention discloses a processing technology of a high-strength mobile phone middle frame aluminum alloy section, which comprises the following steps: 1) preparing an aluminum alloy ingot, and preparing an aluminum alloy raw material according to the following weight part ratio: 0.74-0.77% of Si, less than or equal to 0.11% of Fe, 0.63-0.66% of Cu, 0.10-0.12% of Mn, 0.96-0.99% of Mg, less than or equal to 0.03% of Zn, 0.004-0.008% of Ti, less than or equal to 0.01% of single impurity, less than or equal to 0.05% of impurity in total, and the balance of Al; 2) homogenizing the cast aluminum alloy ingot at the temperature of 520-530 ℃ and at the temperature of 555-565 ℃; 3) brushing a rod or peeling off the surface; 4) heating the brush rod or the peeled aluminum alloy ingot at the temperature of 555-570 ℃; then putting the mixture into a ingot containing barrel of an extruder for extrusion, wherein the extrusion speed is 5-10 m/min; 5) cooling the extruded section product, and then correcting by 0.3-0.8%; 6) and (5) artificial aging treatment. The aluminum profile prepared by the invention can obtain good surface effect after being polished and oxidized by CNC processing machinery, has high glossiness and transparent surface, and completely meets the terminal requirements of the middle frame product of the mobile phone.)

1. A processing technology of a high-strength mobile phone middle frame aluminum alloy section is characterized by comprising the following steps:

1) preparing an aluminum alloy raw material according to the following weight part ratio: si: 0.74-0.77%, Fe: less than or equal to 0.11 percent, Cu: 0.63-0.66%, Mn: 0.10-0.12%, Mg: 0.96-0.99%, Zn: less than or equal to 0.03 percent, Ti: 0.004-0.008% of the total content of the impurities, less than or equal to 0.01% of the single impurities, less than or equal to 0.05% of the total content of the impurities and the balance of Al; melting the prepared aluminum alloy raw material, secondarily filtering impurities through a tubular filter box, and then casting into an aluminum alloy ingot;

2) homogenizing the cast aluminum alloy ingot at the temperature of 520-530 ℃, heating to the temperature of 555-565 ℃, homogenizing for the second time, and cooling at the cooling speed of more than 300 ℃/h;

3) performing surface brushing or peeling treatment on the homogenized aluminum alloy cast ingot surface;

4) heating the brush rod or the peeled aluminum alloy ingot at the temperature of 555-570 ℃; then putting the mixture into a ingot containing barrel of an extruder for extrusion, wherein the extrusion speed of the product is 5-10m/min, and cooling the product after extrusion, wherein the cooling speed is more than 400 ℃/min;

5) cooling the extruded section product, and then correcting by 0.3-0.8%;

6) and (5) artificial aging treatment.

2. The processing technology of the high-strength aluminum alloy section for the middle frame of the mobile phone according to claim 1, wherein in the step 1), AL is an aluminum ingot with purity of not less than 99.8%.

3. The processing technology of the high-strength aluminum alloy section for the middle frame of the mobile phone, according to claim 1, is characterized in that in the step 1), the melting process is as follows: adding the prepared aluminum alloy raw material into a smelting furnace to be melted into aluminum liquid, then uniformly stirring by using an electromagnetic stirring device, refining and degassing by using a refining agent, standing for 30-60 minutes to precipitate impurities, and then filtering the residual impurities in the aluminum liquid by using a 40-60-mesh ceramic filter plate.

4. The processing technology of the aluminum alloy profile for the middle frame of the high-strength mobile phone according to claim 1, wherein in the step 2), the heat preservation homogenization treatment time for the first homogenization is 14-18h, and the heat preservation homogenization treatment time for the second homogenization is 4-6 h.

5. The processing technology of the aluminum alloy profile for the middle frame of the high-strength mobile phone according to claim 1, wherein in the step 2), the cooling adopts a mode of air cooling and water cooling.

6. The processing technology of the aluminum alloy profile for the middle frame of the high-strength mobile phone according to claim 1, wherein in the step 4), the temperature of the extruded ingot container is controlled to be 440-460 ℃.

7. The processing technology of the aluminum alloy profile for the middle frame of the high-strength mobile phone according to claim 1, wherein in the step 4), the extruded profile is cooled by water.

8. The processing technology of the high-strength aluminum alloy section for the middle frame of the mobile phone according to claim 1, characterized in that the specific method of artificial aging treatment is as follows: carrying out single-stage artificial aging treatment on the extruded section, wherein the aging temperature is 175-185 ℃, the aging heat preservation time is 8-10h, and a peak aging process is used.

Technical Field

The invention relates to the technical field of aluminum profile processing and manufacturing, in particular to a processing technology of a high-strength aluminum alloy profile of a middle frame of a mobile phone.

Background

At present, with the development of the mobile phone industry, the requirements of consumers on the appearance of the mobile phone are increasingly raised, and the surface of the middle frame in the appearance of the mobile phone needs to have the characteristics of high gloss and bright color, so that the requirements of mobile phone brand manufacturers on the surface of a supply chain product are forced to be higher and higher. Meanwhile, along with the development of the communication industry, 5G is about to fall to the ground for use in a large amount, and in order to meet the requirements of the mobile phone 5G, the volume of internal communication elements, antennas and the like is larger and larger, but the whole mobile phone is required to be light and thin, so the volume of the middle frame of the mobile phone is continuously compressed, but the middle frame plays a key role in the integral rigidity strength of the mobile phone, and along with the reduction of the volume, the middle frame inevitably needs higher strength to support, otherwise the mobile phone is easy to bend. In addition, with the development of 5G, the communication frequency is increased, the rear cover of the mobile phone needs to be made of glass and other materials which cannot influence signals, but when the mobile phone falls accidentally, the mobile phone is easy to break and damage, so that the falling performance can be enhanced only by enhancing the strength of the middle frame.

In the conventional high-strength 6-series aluminum alloy, the recrystallization temperature is generally increased by using elements such as Mn, Cr, Zr and the like, so that crystal grains are in a fine fibrous shape, and the effect of fine-grain reinforcement is provided for the profile. However, for the mobile phone middle frame product with high oxidation surface requirement, if the crystal grains are too fine, the glossiness of the mobile phone middle frame product is reduced after oxidation, so that the surface requirement of the terminal cannot be met, and the over-large crystal grains cause the defect of similar mottled appearance on the surface after oxidation. In addition, although the 6-series high-strength alloy generally contains an excessive amount of Mg and Si elements to ensure a solid solution effect, if Mg and Si added to the mobile phone middle frame having a high surface demand cannot be completely dissolved in a solid solution, Mg will be generated₂The precipitation and aggregation of the coarse Si strengthening phase can remain in the oxide film during oxidation, so that the phenomenon of refraction during light reflection is caused, the oxide film is in an impermeable condition, and the surface requirement of a customer can not be met.

Therefore, it is very important to research the production of the middle frame product of the mobile phone, which has high strength and can meet the final high oxidation surface requirement, in the current stage.

Disclosure of Invention

The invention aims to provide a processing technology of an aluminum alloy section which has high strength, high surface glossiness and permeability after oxidation processing and is suitable for manufacturing a middle frame of a mobile phone.

In order to achieve the purpose, the invention adopts the following technical scheme.

A processing technology of a high-strength mobile phone middle frame aluminum alloy section is characterized by comprising the following steps: 1) preparing an aluminum alloy raw material according to the following weight part ratio: si: 0.74-0.77%, Fe: less than or equal to 0.11 percent, Cu: 0.63-0.66%, Mn: 0.10-0.12%, Mg: 0.96-0.99%, Zn: less than or equal to 0.03 percent, Ti: 0.004-0.008% of the total content of the impurities, less than or equal to 0.01% of the single impurities, less than or equal to 0.05% of the total content of the impurities and the balance of Al; melting the prepared aluminum alloy raw material, secondarily filtering impurities through a tubular filter box, and then casting into an aluminum alloy ingot; 2) homogenizing the cast aluminum alloy ingot at the temperature of 520-530 ℃, heating to the temperature of 555-565 ℃, homogenizing for the second time, and cooling at the cooling speed of more than 300 ℃/h; 3) performing surface brushing or peeling treatment on the homogenized aluminum alloy cast ingot surface; 4) heating the brush rod or the peeled aluminum alloy ingot at the temperature of 555-570 ℃; then putting the mixture into a ingot containing barrel of an extruder for extrusion, wherein the extrusion speed of the product is 5-10m/min, and cooling the product after extrusion, wherein the cooling speed is more than 400 ℃/min; 5) cooling the extruded section product, and then correcting by 0.3-0.8%; 6) and (5) artificial aging treatment.

More preferably, in step 1), AL is an aluminum ingot having a purity of 99.8% or more.

More preferably, in step 1), the melting process is: adding the prepared aluminum alloy raw material into a smelting furnace to be melted into aluminum liquid, then uniformly stirring by using an electromagnetic stirring device, refining and degassing by using a refining agent, standing for 30-60 minutes to precipitate impurities, and then filtering the residual impurities in the aluminum liquid by using a 40-60-mesh ceramic filter plate.

More preferably, in step 2), the time period for the first homogenization heat-preservation homogenization treatment is 14 to 18 hours, and the time period for the second homogenization heat-preservation homogenization treatment is 4 to 6 hours.

More preferably, in step 2), the cooling is performed by air cooling and water cooling.

More preferably, in the step 4), the temperature of the extruded ingot container is controlled to be 440-460 ℃.

More preferably, in step 4), the extruded profile is cooled using water.

More preferably, the specific method of artificial aging treatment is as follows: carrying out single-stage artificial aging treatment on the extruded section, wherein the aging temperature is 175-185 ℃, the aging heat preservation time is 8-10h, and a peak aging process is used.

The invention has the beneficial effects that:

through practical tests, the performance indexes of the high-strength aluminum alloy section for the middle frame of the mobile phone provided by the invention are as follows: the tensile strength is more than 420Mpa, the yield strength is more than 400Mpa, and the elongation after fracture is more than 5 percent and is far greater than the mechanical properties of other 6-series aluminum alloys. Meanwhile, a good surface effect can be obtained after the CNC processing machine is polished and oxidized, the glossiness is high, the surface is transparent, and the terminal requirements of the middle frame product of the mobile phone are completely met.

Detailed Description

The following further describes the embodiments of the present invention, so that the technical solutions and the advantages thereof of the present invention are more clear and definite. The following description of the embodiments is exemplary in nature and is in no way intended to limit the invention.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

A processing technology of a high-strength mobile phone middle frame aluminum alloy section is characterized by comprising the following steps:

1) preparing the aluminum alloy according to the following weight part ratio: si: 0.74-0.77%, Fe: less than or equal to 0.11 percent, Cu: 0.63-0.66%, Mn: 0.10-0.12%, Mg: 0.96-0.99%, Zn: less than or equal to 0.03 percent, Ti: 0.004-0.008%, less than or equal to 0.01% of single impurity, less than or equal to 0.05% of impurity in total, and the balance of Al. The method comprises the following steps of preparing an aluminum alloy raw material, adding the prepared aluminum alloy raw material into a smelting furnace to be melted into aluminum liquid, uniformly stirring the aluminum liquid by using an electromagnetic stirring device after the aluminum ingot with purity being more than or equal to 99.8% is used for AL, standing the aluminum liquid for 30-60 minutes after refining and degassing by using a refining agent, precipitating impurities, filtering residual impurities in the aluminum liquid by using a 40-60-mesh ceramic filter plate, secondarily filtering the impurities by using a tubular filter box, and finally casting the aluminum liquid into an aluminum alloy ingot.

When the aluminum alloy is prepared, the content of Cu cannot be too high, so that the yellow color and color cast of the oxidized aluminum alloy can be avoided. The content of Mn is controlled to be 0.10-0.12%, the beta-Fe phase can be promoted to be rapidly converted into the alpha-Fe phase, the influence of the alpha-Fe phase on the extrusion performance is reduced, and the influence of the acicular alpha-Fe phase remaining in an oxidation film on the oxidation color is avoided. The purpose of the tubular filtration is to ensure that the impurity with the particle size of more than 10 mu m can reach the removal rate of more than 99 percent and avoid the subsequent residue in the oxidation film from influencing the oxidation quality.

2) And (3) performing heat preservation homogenization treatment on the cast aluminum alloy ingot at the temperature of 520-530 ℃ for 14-18h, heating to the temperature of 555-565 ℃, continuing homogenizing and heat preservation for 4-6h, and cooling by using an air cooling and water cooling mode after homogenization treatment, wherein the cooling speed is higher than 300 ℃/h. The method comprises the steps of firstly ensuring that most of the components are basically fused into a matrix through primary low-temperature homogenization, reducing the condition of grain boundary segregation, preventing the components from being melted at high temperature to form an overburning defect, and then ensuring that Mg and Si reach the temperature of complete solid solution and are completely dissolved into the matrix through high-temperature homogenization, so as to avoid the condition that the performance is reduced and the oxidized surface is influenced because the Mg and the Si cannot be completely dissolved in the extrusion process. The control of cooling speed can avoid Mg₂Si precipitation and growth, and further Mg₂Si can be completely redissolved in the extrusion process, so that the performance reduction and the influence on the surface oxidation effect are avoided.

3) And (3) carrying out surface brushing or peeling treatment on the surface of the homogenized aluminum alloy cast ingot so as to avoid the influence of impurities of a surface segregation layer on the oxidation effect caused by rolling into a forming material in the extrusion process.

4) Heating the brush rod or the peeled aluminum alloy cast ingot, putting the heated brush rod or the peeled aluminum alloy cast ingot into an ingot containing cylinder of an extruder for extrusion at the temperature of 555-570 ℃, wherein the extrusion speed of the product is 5-10m/min, and cooling the extruded product by water at the cooling speed of more than 400 ℃/min. Because the Mg and Si contents in the alloy are high and the alloy contains certain Mn elements, the quenching sensitivity is high, and the cooling speed of more than 400 ℃/min can ensure that the solid-dissolved Mg and Si can not be separated out in the cooling process, thereby avoiding influencing the mechanical property and the oxidation effect of the section. The temperature of the extrusion ingot containing barrel is controlled to be 440-460 ℃, so that the problem that the extrusion temperature cannot reach the solid solution requirement due to excessive temperature reduction of the aluminum bar in the ingot containing barrel is avoided.

5) And (3) cooling the extruded profile product, and then correcting, wherein the correction amount is 0.3-0.8%, and the correction amount must be controlled, so that the situation that the internal stress of the profile cannot be released due to too small correction amount is avoided, and meanwhile, the situation that the dimension of the profile is influenced due to too long correction length is also avoided.

6) Carrying out single-stage artificial aging treatment on the extruded section, wherein the aging temperature is 175-185 ℃, the aging heat preservation time is 8-10h, and a peak aging process is used.

Through practical tests, the performance indexes of the high-strength aluminum alloy section for the middle frame of the mobile phone provided by the embodiment are that the tensile strength is greater than 420Mpa, the yield strength is greater than 400Mpa, and the elongation after fracture is greater than 5%, which is far greater than the mechanical properties of other 6-series aluminum alloys. Meanwhile, a good surface effect can be obtained after the CNC processing machine is polished and oxidized, the glossiness is high, the surface is transparent, and the terminal requirements of the middle frame product of the mobile phone are completely met.

It will be understood by those skilled in the art from the foregoing description that the present invention is not limited to the specific embodiments described above, and that modifications and substitutions based on the known art are intended to be included within the scope of the present invention as defined by the appended claims and their equivalents. The details not described in the detailed description are prior art or common general knowledge.