Extrusion die and method for controlling grain size of 6-series aluminum alloy mobile phone plate

Abstract

According to the extrusion die and method for controlling the grain size of the 6-series aluminum alloy mobile phone plate, by means of the die pressurization method, grain crushing is more thorough in the casting rod extrusion process, then a finer grain structure is obtained, the product discharging temperature is increased in the die pressurization mode, the product quenching effect is improved, and the product quality is improved. Compared with a traditional flat-die-like die, the grain size of the mobile phone plate profile is reduced by 35%-45%, the expectation that the average grain size is smaller than 150 micrometers is achieved, and the product strength and oxidation performance are more stable and excellent.

Description

Technical Field

[0001] The invention relates to an extrusion die and a method for controlling the grain size of a 6-series aluminum alloy mobile phone plate, and belongs to the technical field of aluminum alloy material production. Background Art

[0002] With the development of communication and digital technology, 3C products have been continuously upgraded in the past two decades, becoming a microcosm of technological development and rapidly expanding the market for 3C products. The advantages of aluminum alloy such as lightweight, excellent metal texture, and easy processing make it a hot commodity in the field of 3C market materials. Mobile phone frames and decorative parts are an important part of 3C products. The 6063 alloy is currently widely used in the market. As the requirements of the end-user continue to increase, various manufacturers are currently developing higher-strength aluminum alloy materials. Some manufacturers have begun to develop mobile phone frames and decorative parts in the direction of 7 series aluminum alloys. Among the high-strength 6 series aluminum alloys, 6013 alloy has high strength and good oxidation performance, but when producing mobile phone blanks, it will cause problems such as oxidation spots and discoloration due to coarse grains, resulting in batch defective scrapping. The problem of coarse grains has not yet been effectively solved in the domestic market.

[0003] The aluminum alloy mobile phone frame material is completed through smelting, melt purification, casting, casting rod homogenization, casting rod heating, extrusion, heat treatment, finishing, oxidation and other processes. Among them, melt purification, casting rod heating and extrusion process are particularly important for product quality, and the extrusion speed and die structure in the extrusion process are the key points to control the grain size of the product. The traditional process is that the casting rod is formed by a flat die through rapid extrusion (extrusion speed 10-12m / min), and rapid quenching is achieved through rapid extrusion to limit the growth of grains, thereby achieving refined product grains. The extrusion pressure is 10-12MPa, the largest grain size is about 600-800μm, and the average grain size is 190μm; the main characteristics of mobile phone boards produced by the traditional process are as follows: 1. The product discharge temperature remains unchanged or slightly reduced, and the stability of the product's mechanical properties cannot be guaranteed; 2. The grain structure of the product edge is fine and the grain structure of the center is coarse, which seriously affects the subsequent oxidation effect; 3. The glossiness of the product after oxidation is uneven, which is easy to cause color difference. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides an extrusion die for controlling the grain size of 6 series aluminum alloy mobile phone plate materials, comprising a die body, wherein one side of the die body is provided with a feed port, and the other side is provided with a feed port, and a working belt is provided in the die body, one end of the working belt is connected to the feed port, and a die storage chamber is formed between the other end of the working belt and the feed port, and the cross-section of the die storage chamber is arranged to decrease in a step-like manner from the feed port to the working belt.

[0005] Preferably, a method for controlling the grain size of a 6-series aluminum alloy mobile phone sheet using an extrusion die comprises the following steps:

[0006] 1) Alloy smelting and casting: Aluminum ingots, magnesium ingots and various master alloys are put into the smelting furnace for smelting according to the alloy ratio requirements. The smelting temperature is controlled at 720-750℃. After the material is completely melted, the melt is purified by refining agent and argon gas. Before casting, the melt passes through a degassing box and a filter box to further purify the melt quality. Finally, the melt is introduced into the casting plate to complete the casting of the cast rod;

[0007] 2) Cast rod homogenization: The cast rods are sent to a homogenization furnace and heated to 560-570°C for 15-17 hours, then taken out of the furnace and cooled to obtain cast rods;

[0008] 3) Cast rod extrusion and heat treatment: The homogenized cast rod is sent to the heating furnace of the extruder to be heated to 550-570℃, and then enters the extruder for extrusion molding at a medium speed. The extrusion speed is controlled to 6-12m / min. The grains are crushed by multi-stage supercharging of the extrusion die. The medium speed can give some small grains a chance to grow, so that the overall grain size of the product is more uniform. The cast rod is extruded into the required mobile phone plate profile through the extrusion die by the extruder, and then the mobile phone plate profile is transported to the aging furnace for aging treatment. The aging temperature is 160-180℃ and the heat preservation is 8-10h.

[0009] 4) The aged profiles are processed into standard samples by CNC, and then oxidized after cleaning.

[0010] Preferably, the refining agent in step 1) is sodium-free granular refining agent MK4844B.

[0011] Preferably, the extrusion speed in step 3) is 6-8 m / min.

[0012] Preferably, in step 3), the extrusion pressure is 15-18 MPa, the maximum grain size is 300-500 μm, and the average grain size is less than 150 μm.

[0013] Preferably, in step 3), the average grain size is 120 μm.

[0014] Preferably, in step 3), the multi-stage pressurization of the extrusion die is specifically as follows: the aluminum alloy cast rod enters the die storage chamber after extrusion, and the cross-section of the die storage chamber is arranged in a step-by-step decreasing direction from the feed inlet to the working zone, the inlet area is continuously reduced, the pressure on the cast rod is continuously increased, the grain structure is intensified, and a dense and fine grain structure is formed after reaching the die working zone, and finally flows out of the die from the discharge port.

[0015] The present invention provides an extrusion die and method for controlling the grain size of 6 series aluminum alloy mobile phone plates. The present invention uses a die pressurization method to make the grains more completely broken during the extrusion of the cast rod, thereby obtaining a finer grain structure; the die pressurization method increases the product discharge temperature and improves the product quenching effect. Compared with the traditional flat die, the grain size of the mobile phone plate profile is 35%-45% smaller, reaching the expected average grain size of less than 150μm, and the product strength and oxidation performance are more stable and excellent. Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0016] 1. The product grain structure is finer and more uniform, which is beneficial to the subsequent oxidation process and avoids oxidation defects;

[0017] 2. The product passes through the mold to increase the discharge temperature, ensure the mechanical properties of the product, reduce the heating temperature of the casting rod and reduce energy consumption;

[0018] 3. The discharge temperature is increased by pressurizing the mold, which provides a layer of protection for the stability of the product's mechanical properties;

[0019] 4. Through the characteristics of die pressurization and medium-speed extrusion, the grain structure of the product is made finer and more uniform. At the same time, the slower speed can reduce the loss of the die and increase the life of the die;

[0020] 5. The mold pressurization method is used to ensure uniform oxidation gloss, avoid product color difference, and improve product qualification rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the extrusion die of the present invention.

[0022] The accompanying drawings are marked as: 1-mold body, 11-feeding port, 12-working belt, 13-discharging port, 14-mold storage chamber. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with the accompanying drawings.

[0024] Example 1

[0025] like Figure 1 As shown, an extrusion die for controlling the grain size of 6 series aluminum alloy mobile phone plate material comprises a die body 1, wherein one side of the die body 1 is provided with a feed port 11, and the other side is provided with a discharge port 13, a working belt 12 is provided inside the die body 1, one end of the working belt 12 is connected with the discharge port 13, and a die storage chamber 14 is formed between the other end of the working belt 12 and the feed port 11, and the cross section of the die storage chamber 14 is arranged to decrease in a step-like manner from the feed port 11 to the working belt 12.

[0026] A method for controlling the grain size of a 6-series aluminum alloy mobile phone plate using an extrusion die comprises the following steps:

[0027] 1) Alloy smelting and casting: Aluminum ingots, magnesium ingots and various master alloys are put into the smelting furnace for smelting according to the alloy ratio requirements. The smelting temperature is controlled at 720°C. After the materials are completely melted, the melt is purified by sodium-free particle refining agent MK4844B and argon gas. Before casting, the melt passes through a degassing box and a filter box to further purify the melt quality. Finally, the melt is introduced into the casting plate to complete the casting of the cast rod;

[0028] 2) Cast rod homogenization: The cast rods are sent to a homogenization furnace and heated to 560°C for 15 hours, then taken out of the furnace and cooled to obtain cast rods;

[0029] 3) Cast rod extrusion and heat treatment: The homogenized cast rod is sent to the heating furnace of the extruder to be heated to 550°C, and then enters the extruder for extrusion molding at a medium speed. The extrusion speed is controlled to 6m / min, the extrusion pressure is 15MPa, and the grains are crushed by multi-stage supercharging of the extrusion die. After extrusion, the aluminum alloy cast rod enters the die storage chamber 14. The cross section of the die storage chamber 14 is arranged in a step-by-step decreasing manner from the feed port 11 to the working belt 12. The inlet area is continuously reduced, the pressure on the cast rod is continuously increased, and the grain structure is intensified. After reaching the working belt of the mold, a dense fine grain structure is formed, and finally flows out of the mold from the discharge port 13. The medium speed can give some fine grains a chance to grow, so that the overall grain size of the product is more uniform, the largest grain size is 300μm, and the average grain size is 120μm. The cast rod is extruded by the extruder through the extrusion die to extrude the required mobile phone plate profile, and then the mobile phone plate profile is transported to the aging furnace for aging treatment. The aging temperature is 160°C and the heat preservation is 8h;

[0030] 4) The aged profiles are processed into standard samples by CNC, and then oxidized after cleaning.

[0031] Example 2

[0032] like Figure 1 As shown, an extrusion die for controlling the grain size of 6 series aluminum alloy mobile phone plate material comprises a die body 1, wherein one side of the die body 1 is provided with a feed port 11, and the other side is provided with a discharge port 13, a working belt 12 is provided inside the die body 1, one end of the working belt 12 is connected with the discharge port 13, and a die storage chamber 14 is formed between the other end of the working belt 12 and the feed port 11, and the cross section of the die storage chamber 14 is arranged to decrease in a step-like manner from the feed port 11 to the working belt 12.

[0033] A method for controlling the grain size of a 6-series aluminum alloy mobile phone plate using an extrusion die comprises the following steps:

[0034] 1) Alloy smelting and casting: Aluminum ingots, magnesium ingots and various master alloys are put into the smelting furnace for smelting according to the alloy ratio requirements. The smelting temperature is controlled at 730°C. After the materials are completely melted, the melt is purified by sodium-free particle refining agent MK4844B and argon gas. Before casting, the melt passes through a degassing box and a filter box to further purify the melt quality. Finally, the melt is introduced into the casting plate to complete the casting of the cast rod;

[0035] 2) Cast rod homogenization: The cast rods are sent to a homogenization furnace and heated to 565°C for 16 hours, then taken out of the furnace and cooled to obtain cast rods;

[0036] 3) Cast rod extrusion and heat treatment: The homogenized cast rod is sent to the heating furnace of the extruder to be heated to 560°C, and then enters the extruder for extrusion molding at a medium speed. The extrusion speed is controlled to 8m / min, the extrusion pressure is 16MPa, and the grains are crushed by multi-stage supercharging of the extrusion die. After extrusion, the aluminum alloy cast rod enters the die storage chamber 14. The cross section of the die storage chamber 14 is arranged in a step-by-step decreasing manner from the feed port 11 to the working belt 12. The inlet area is continuously reduced, the pressure on the cast rod is continuously increased, and the grain structure is intensified. After reaching the working belt of the mold, a dense fine grain structure is formed, and finally flows out of the mold from the discharge port 13. The medium speed can give some fine grains a chance to grow, so that the overall grain size of the product is more uniform, the largest grain size is 400μm, and the average grain size is 130μm. The cast rod is extruded by the extruder through the extrusion die to extrude the required mobile phone plate profile, and then the mobile phone plate profile is transported to the aging furnace for aging treatment. The aging temperature is 170°C and the heat preservation is 9h;

[0037] 4) The aged profiles are processed into standard samples by CNC, and then oxidized after cleaning.

[0038] Example 3

[0039] like Figure 1 As shown, an extrusion die for controlling the grain size of 6 series aluminum alloy mobile phone plate material comprises a die body 1, wherein one side of the die body 1 is provided with a feed port 11, and the other side is provided with a discharge port 13, a working belt 12 is provided inside the die body 1, one end of the working belt 12 is connected with the discharge port 13, and a die storage chamber 14 is formed between the other end of the working belt 12 and the feed port 11, and the cross section of the die storage chamber 14 is arranged to decrease in a step-like manner from the feed port 11 to the working belt 12.

[0040] A method for controlling the grain size of a 6-series aluminum alloy mobile phone plate using an extrusion die comprises the following steps:

[0041] 1) Alloy smelting and casting: Aluminum ingots, magnesium ingots and various master alloys are put into the smelting furnace for smelting according to the alloy ratio requirements. The smelting temperature is controlled at 750°C. After the materials are completely melted, the melt is purified by sodium-free particle refining agent MK4844B and argon gas. Before casting, the melt passes through a degassing box and a filter box to further purify the melt quality. Finally, the melt is introduced into the casting plate to complete the casting of the cast rod;

[0042] 2) Cast rod homogenization: The cast rods are sent to a homogenization furnace and heated to 570°C for 17 hours, then taken out of the furnace and cooled to obtain cast rods;

[0043] 3) Cast rod extrusion and heat treatment: The homogenized cast rod is sent to the heating furnace of the extruder to be heated to 570°C, and then enters the extruder for extrusion molding at a medium speed. The extrusion speed is controlled to 12m / min, the extrusion pressure is 18MPa, and the grains are crushed by multi-stage supercharging of the extrusion die. After extrusion, the aluminum alloy cast rod enters the die storage chamber 14. The cross section of the die storage chamber 14 is arranged in a step-by-step decreasing manner from the feed port 11 to the working belt 12. The inlet area is continuously reduced, the pressure on the cast rod is continuously increased, and the grain structure is intensified. After reaching the working belt of the mold, a dense fine grain structure is formed, and finally flows out of the mold from the discharge port 13. The medium speed can give some fine grains a chance to grow, so that the overall grain size of the product is more uniform, the largest grain size is 500μm, and the average grain size is 140μm. The cast rod is extruded by the extruder through the extrusion die to extrude the required mobile phone plate profile, and then the mobile phone plate profile is transported to the aging furnace for aging treatment. The aging temperature is 180°C and the heat preservation is 10h;

[0044] 4) The aged profiles are processed into standard samples by CNC, and then oxidized after cleaning.

[0045] The above-described embodiments only express the preferred embodiments of the present invention, and the description thereof is relatively specific and detailed, but the present invention is not limited to these embodiments. It should be noted that it is obvious to those skilled in the art. Without departing from the purpose of the present invention, any improvement made shall fall within 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. An extrusion die for controlling the grain size of 6 series aluminum alloy mobile phone sheet, characterized in that: The invention comprises a mould body (1), wherein one side of the mould body (1) is provided with a material inlet (11), and the other side is provided with a material outlet (13), a working belt (12) is provided inside the mould body (1), one end of the working belt (12) is connected with the material outlet (13), a mould material storage chamber (14) is formed between the other end of the working belt (12) and the material inlet (11), and the cross section of the mould material storage chamber (14) is arranged to decrease in a step-like manner from the material inlet (11) to the working belt (12).

2. A method for controlling the grain size of 6 series aluminum alloy mobile phone sheet using the extrusion die according to claim 1, characterized in that: The following steps are involved: 1) Alloy smelting and casting: Aluminum ingots, magnesium ingots and various master alloys are put into the smelting furnace for smelting according to the alloy ratio requirements. The smelting temperature is controlled at 720-750℃. After the material is completely melted, the melt is purified by refining agent and argon gas. Before casting, the melt passes through a degassing box and a filter box to further purify the melt quality. Finally, the melt is introduced into the casting plate to complete the casting of the cast rod; 2) Cast rod homogenization: The cast rods are sent to a homogenization furnace and heated to 560-570°C for 15-17 hours, then taken out of the furnace and cooled to obtain cast rods; 3) Cast rod extrusion and heat treatment: The homogenized cast rod is sent to the heating furnace of the extruder to be heated to 550-570℃, and then enters the extruder for extrusion molding at a medium speed. The extrusion speed is controlled to 6-12m / min. The grains are crushed by multi-stage supercharging of the extrusion die. The medium speed can give some small grains a chance to grow, so that the overall grain size of the product is more uniform. The cast rod is extruded into the required mobile phone plate profile through the extrusion die by the extruder, and then the mobile phone plate profile is transported to the aging furnace for aging treatment. The aging temperature is 160-180℃ and the heat preservation is 8-10h. 4) The aged profiles are processed into standard samples by CNC, and then oxidized after cleaning.

3. The method for controlling the grain size of 6 series aluminum alloy mobile phone sheet material according to claim 2, characterized in that: In step 1), the refining agent is sodium-free granular refining agent MK4844B.

4. The method for controlling the grain size of 6 series aluminum alloy mobile phone sheet material according to claim 2, characterized in that: In step 3), the extrusion speed is 6-8 m / min.

5. The method for controlling the grain size of 6 series aluminum alloy mobile phone sheet material according to claim 2, characterized in that: In step 3), the extrusion pressure is 15-18 MPa, the maximum grain size is 300-500 μm, and the average grain size is less than 150 μm.

6. The method for controlling the grain size of 6 series aluminum alloy mobile phone sheet material according to claim 4, characterized in that: The average grain size in step 3) is 120 μm.

7. The method for controlling the grain size of 6 series aluminum alloy mobile phone sheet material according to claim 2, characterized in that: In step 3), the multi-stage pressurization of the extrusion die is specifically as follows: the aluminum alloy cast rod enters the die storage chamber (14) after extrusion, and the cross-section of the die storage chamber (14) is arranged in a step-by-step manner from the feed inlet (11) to the working zone (12). The inlet area is continuously reduced, and the pressure on the cast rod is continuously increased, and the grain structure is intensified. After reaching the die working zone, a dense fine grain structure is formed, and finally flows out of the die from the discharge port (13).

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