Method for producing aluminium alloy bars and their use in the photovoltaic sector

Abstract

The present application relates to a production method of aluminum alloy rod and its application in photovoltaic field, after smelting, slagging and stirring of raw materials, adjusting components to obtain aluminum alloy melt, the melt is refined in a refining furnace, degassing to obtain refined melt; the refined melt is placed and cast to obtain aluminum alloy ingot, after homogenizing annealing of the aluminum alloy ingot, the aluminum alloy ingot is extruded by an extruder to obtain aluminum alloy rod. The refining furnace is provided with a graphite stirring head and two graphite electrode assemblies, and the two graphite electrode assemblies are connected to a pulse power supply. The high and low temperature change resistance of the obtained aluminum alloy rod is significantly improved, so that the aluminum alloy rod is particularly suitable for application in photovoltaic field.

Description

Technical Field

[0001] This invention relates to a method for producing aluminum alloy rods and their application in the photovoltaic field, belonging to the technical field of aluminum alloy rod production in the photovoltaic field. Background Technology

[0002] 6-series aluminum alloys have many advantages, such as low density, wide range of mechanical properties, good weather resistance and corrosion resistance. Their bars and corresponding processed products are very suitable for the photovoltaic field.

[0003] In the photovoltaic field, for example, the support frame of solar photovoltaic panels is usually made of 6-series aluminum alloy, which is required to have a service life of more than 25 years.

[0004] However, the above performance requirements only meet the needs of outdoor use in general areas. For some special climatic regions, such as the Qinghai-Tibet Plateau with abundant solar energy resources, where the diurnal temperature range is large, especially in permafrost areas, the demand for photovoltaic equipment is more urgent. Taking the commonly used 6005 aluminum alloy as an example, its yield strength decreases significantly under diurnal temperature variations of -25℃ to 20℃. This change is mainly due to insufficient uniform crystallization during the aluminum alloy smelting process, preventing further grain refinement and resulting in limited resistance to high and low temperature changes. For example, in a high and low temperature cycling test (cycle temperature -25℃ to 20℃, 1000 cycles) in a high and low temperature cycling oven, the yield strength of the 6005 aluminum alloy before and after the test showed a decrease of nearly 50%.

[0005] Based on this, the present invention is proposed. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing a method for producing aluminum alloy rods and their application in the photovoltaic field. The specific technical solution is as follows:

[0007] The production method of aluminum alloy bars includes the following steps:

[0008] Step 1: Weigh the raw materials according to the formula, melt them, remove the slag and stir, adjust the composition to obtain aluminum alloy melt;

[0009] Step 2: Refine and degas in a refining furnace to obtain refined molten liquid;

[0010] Step 3: The refined molten liquid is allowed to stand and then cast to obtain aluminum alloy ingots. After homogenization annealing, the aluminum alloy ingots are extruded using an extruder to produce aluminum alloy bars.

[0011] A further improvement is made to the formulation of the aluminum alloy bar, which, by weight percentage, includes the following components:

[0012] Cu: 0.13–0.39%; Mn: 0.12–0.15%; Mg: 0.8–1.0%; Zn: 0.15–0.2%; Zr: 0.05–0.08%; Cr: 0.06–0.07%; Ti: 0.12%; Si: 0.5–0.6%; Fe: ≤0.3%; balance Al.

[0013] In a further improvement, in step 3, the casting temperature is 700–710℃ and the casting speed is 11–12 m / min.

[0014] In a further improvement, in step 3, the temperature at the outlet of the extruder is controlled at 535-540°C, and online water mist cooling is used for quenching after extrusion.

[0015] In a further improvement, the refining furnace is equipped with a graphite stirring head and a hollow graphite rod coaxially connected to the graphite stirring head; the refining furnace is also equipped with two graphite electrode assemblies, each graphite electrode assembly including a graphite outer tube, a hollow insulating rod coaxially arranged with the graphite outer tube, and a copper pendulum. The graphite outer tube and the hollow insulating rod are rotatably connected by a bearing. The upper end of the hollow insulating rod and the channel inside the hollow graphite rod are both connected to a nitrogen source. A copper spring is fixedly installed between the upper end of the copper pendulum and the hollow insulating rod. The upper end of the copper spring is located inside the graphite outer tube, and the copper pendulum is located below the graphite outer tube.

[0016] Two copper springs are electrically connected to the two poles of the pulse power supply, respectively.

[0017] In a further improvement, the rotational speed of the graphite stirring head is 450–500 r / min, and the flow rate of nitrogen gas blown into the molten aluminum alloy by the hollow graphite rod is 1.1–1.8 m³ / min. 3 / h; the nitrogen flow rate blown into the molten aluminum alloy by the hollow insulating rod is greater than the nitrogen flow rate blown into the molten aluminum alloy by the hollow graphite rod, and the difference in flow rate is 0.6~0.7m. 3 / h; the rotational speed of the graphite outer tube is less than that of the graphite stirring head, and the difference in rotational speed between the two is 80-100 r / min; the rotational direction of the graphite outer tube in the first graphite electrode assembly is opposite to that in the second graphite electrode assembly.

[0018] In a further improvement, the pulse power supply has a base output current of 30-35A, a peak value of 310-380A, a pulse frequency of 100-120Hz, and an output current waveform of sawtooth wave.

[0019] In a further improvement, the copper pendulum includes an outer hammer body and a lead hammer body embedded in the outer hammer body and inside it.

[0020] As a further improvement, the lower half of the inner wall of the graphite outer tube is provided with a copper plating layer.

[0021] Further improvements include the application of aluminum alloy rods in the photovoltaic field, wherein the aluminum alloy rods are produced using the aforementioned aluminum alloy rod production method.

[0022] The beneficial effects of this invention are:

[0023] This invention optimizes existing aluminum alloy formulations and further refines the grains through improved refining processes. This refines the size and shape of the grains, resulting in significantly improved mechanical properties of the smelted aluminum alloy rods, particularly their resistance to high and low temperature changes. This makes the aluminum alloy rods especially suitable for photovoltaic applications, particularly for photovoltaic products used in high-altitude regions. Attached Figure Description

[0024] Figure 1 This is a schematic diagram showing the distribution of the two graphite electrode assemblies inside the refining furnace described in this invention.

[0025] Figure 2 This is a schematic diagram of the structure of the graphite electrode assembly described in this invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] In the description of this invention, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] Example 1

[0030] The production method of aluminum alloy bars includes the following steps:

[0031] Step 1: Weigh the raw materials according to the following formula, melt them, remove slag and stir, adjust the composition to obtain aluminum alloy melt;

[0032] The formulation of the aluminum alloy bar, by weight percentage, includes the following components:

[0033] Cu: 0.13–0.39%; Mn: 0.12–0.15%; Mg: 0.8–1.0%; Zn: 0.15–0.2%; Zr: 0.05–0.08%; Cr: 0.06–0.07%; Ti: 0.12%; Si: 0.5–0.6%; Fe: ≤0.3%; balance Al.

[0034] Step 2: Refine and degas in a refining furnace to obtain refined molten liquid;

[0035] Step 3: The refined molten liquid is allowed to stand and then cast (casting temperature is 700-710℃, casting speed is 11-12m / min) to obtain aluminum alloy ingots. After homogenization annealing, the aluminum alloy ingots are extruded using an extruder to produce aluminum alloy bars. The temperature at the outlet of the extruder is controlled at 535-540℃. After extrusion, online water mist cooling is used for quenching treatment.

[0036] like Figure 1 , 2As shown, the refining furnace 10 is equipped with a graphite stirring head 12 and a hollow graphite rod 11 coaxially connected to the graphite stirring head 12; the refining furnace 10 is also equipped with two graphite electrode assemblies, each graphite electrode assembly including a graphite outer tube 22, a hollow insulating rod 21 coaxially arranged with the graphite outer tube 22, and a copper pendulum 26. The graphite outer tube 22 and the hollow insulating rod 21 are rotatably connected by a mounting bearing 24. The upper end of the hollow insulating rod 21 and the channel inside the hollow graphite rod 11 are both connected to a nitrogen source. A copper spring 25 is fixedly installed between the upper end of the copper pendulum 26 and the hollow insulating rod 21. The upper end of the copper spring 25 is located inside the graphite outer tube 22, and the copper pendulum 26 is located below the graphite outer tube 22.

[0037] Two copper springs 25 are respectively connected to the two poles of the pulse power supply.

[0038] The graphite stirring head rotates at 470 r / min, and the nitrogen flow rate blown into the molten aluminum alloy by the hollow graphite rod is 1.1–1.8 m³ / min. 3 / h; the nitrogen flow rate blown into the molten aluminum alloy by the hollow insulating rod is greater than the nitrogen flow rate blown into the molten aluminum alloy by the hollow graphite rod, and the difference in flow rate is 0.6~0.7m. 3 / h; the rotational speed of the graphite outer tube is less than that of the graphite stirring head, and the difference in rotational speed between the two is 85 r / min; the rotational direction of the graphite outer tube in the first graphite electrode assembly is opposite to that in the second graphite electrode assembly.

[0039] The pulse power supply has a base output current of 33A, a peak current of 320A, a pulse frequency of 115Hz, and an output current waveform of sawtooth wave.

[0040] First, because the output current of the pulse power supply forms a huge pulse current between the two graphite electrode assemblies, the hollow graphite rod 11 between the two graphite electrode assemblies rotates and stirs continuously, making the aluminum alloy melt between the two graphite electrode assemblies uneven. The impact force brought by the constantly fluctuating current, coupled with the uneven distribution of the aluminum alloy melt in the initial stage (corresponding to uneven resistance), causes the copper pendulum 26 to swing continuously. The swinging copper pendulum 26 can perform a similar "stirring" effect on the aluminum alloy melt near it, thereby making the aluminum alloy melt in the refining furnace 10 uniformly "stirred with a small amplitude". The stirring time is shortened by more than 36%. Compared with "large amplitude stirring" (such as adding stirring blades, although the stirring efficiency is improved and the stirring time is shortened, the stirring amplitude is too large, resulting in more aluminum alloy melt being thrown up, more aluminum alloy being oxidized, and the amount of slag being significantly increased), the amount of slag removed has no significant change. Thermal imaging clearly shows the swing frequency of the copper pendulum 26. The initial swing frequency is 0.37 to 0.5 Hz, and the later swing frequency is less than 0.2 Hz.

[0041] In the later stages, the crystallization becomes uniform, and the swing amplitude of the copper pendulum 26 decreases significantly (the swing frequency decreases by more than 50%), indicating that the refining process is nearing its end.

[0042] Most importantly, when a pulsed current passes through molten aluminum alloy, especially aluminum ash slag, a large amount of resistance heat is generated as a heat source. This heat source can remelt localized aluminum alloy melts, improve the grain size of the aluminum alloy, and enhance the crystallization effect of the ingot.

[0043] In this invention, the hollow insulating rod 21 is fixed and can be made of silicon nitride. The graphite outer tube 22 is driven to rotate by a gear installed on its upper end, so that there is relative rotation between the graphite outer tube 22 and the hollow insulating rod 21, thereby effectively preventing accumulation between the graphite outer tube 22 and the hollow insulating rod 21.

[0044] As a comparison, if the pulse power supply is replaced with a constant current power supply with a current value of 33A, and everything else remains the same, the initial oscillation frequency becomes 0.17Hz.

[0045] As a comparison, if the rotation direction of the graphite outer tube in the first graphite electrode assembly is the same as that in the second graphite electrode assembly, and everything else remains unchanged, the initial oscillation frequency becomes 0.23Hz.

[0046] The aluminum alloy bar obtained in this embodiment was sampled and marked as sample 1. Its yield strength was tested to be 306 MPa. After 1000 high and low temperature cycle tests (cycle temperature -25℃ to 20℃), the yield strength became 228 MPa. The yield strength decreased by 25.5%.

[0047] Compare with Example 1

[0048] The only difference between this example and Example 1 is that in step 2, during refining and degassing in the refining furnace, a rotary degassing box (i.e., only a hollow graphite rod 11 and a graphite stirring head 12) is used. The rest is the same as in Example 1. The aluminum alloy rod obtained is sampled as Sample 2. Its yield strength is tested to be 298 MPa. After 1000 high and low temperature cycle tests (cycle temperature -25℃ to 20℃), the yield strength becomes 157 MPa. The yield strength decrease is 47.3%.

[0049] A refined molten liquid was obtained;

[0050] Compare with Example 2

[0051] The only difference between this example and Example 1 is that the flow rate of nitrogen gas blown into the molten aluminum alloy by the hollow insulating rod is equal to the flow rate of nitrogen gas blown into the molten aluminum alloy by the hollow graphite rod, and the rotation speed of the graphite outer tube is equal to the rotation speed of the graphite stirring head. The rest is the same as in Example 1. The final aluminum alloy rod is sampled as Sample 3. Its yield strength is tested to be 292 MPa. After 1000 high and low temperature cycle tests (cycle temperature -25℃ to 20℃), the yield strength becomes 163 MPa; the yield strength decreases by 44.2%.

[0052] Compare with Example 3

[0053] The only difference between this example and Example 1 is that the flow rate of nitrogen gas blown into the molten aluminum alloy by the hollow insulating rod is less than the flow rate of nitrogen gas blown into the molten aluminum alloy by the hollow graphite rod, with a flow rate difference of 0.6–0.7 m³ / s. 3 / h; the rotational speed of the graphite outer tube is greater than that of the graphite stirring head, and the difference in rotational speed between the two is 85 r / min; the rest is the same as in Example 1, and the final aluminum alloy rod is sampled as sample 4; its yield strength is tested to be 288 MPa; after 1000 high and low temperature cycle tests (cycle temperature -25℃ to 20℃), the yield strength becomes 141 MPa; the yield strength decreases by 51%.

[0054] Compare with Example 4

[0055] The only difference between this example and Example 1 is that the output current waveform of the pulse power supply is a rectangular wave. The rest is the same as in Example 1. The final aluminum alloy bar is sampled as sample 5. Its yield strength is tested to be 295 MPa. After 1000 high and low temperature cycle tests (cycle temperature -25℃ to 20℃), the yield strength becomes 203 MPa. The yield strength decreases by 31.2%.

[0056] Compare with Example 5

[0057] The only difference between this example and Example 1 is that the output current waveform of the pulse power supply is a stepped wave. The rest is the same as in Example 1. The final aluminum alloy bar is sampled as sample 6. Its yield strength is tested to be 289 MPa. After 1000 high and low temperature cycle tests (cycle temperature -25℃ to 20℃), the yield strength becomes 168 MPa. The yield strength decreases by 41.9%.

[0058] Compare with Example 6

[0059] The only difference between this example and Example 1 is that nitrogen gas is not blown into the molten aluminum alloy in the hollow insulating rod. The rest is the same as in Example 1. The final aluminum alloy rod is sampled as sample 7. Its yield strength is tested to be 294 MPa. After 1000 high and low temperature cycle tests (cycle temperature -25℃ to 20℃), the yield strength becomes 192 MPa. The yield strength decreases by 34.7%.

[0060] Example 2

[0061] In Embodiment 1, the copper pendulum 26 includes an outer hammer body and a lead hammer body embedded in the outer hammer body and inside it. The outer hammer body is made of copper.

[0062] Example 3

[0063] In Example 1, the up-and-down "rhythm" of the copper spring 25 may cause wear on the inner wall of the graphite outer tube 22, potentially introducing new impurities into the aluminum alloy. Therefore, the lower half of the inner wall of the graphite outer tube 22 is provided with a copper plating layer. The copper plating layer is not easily worn, and even if a small amount of copper powder falls into the molten aluminum alloy, it will not affect the formula ratio of the aluminum alloy of this invention, since the aluminum alloy formula of this invention contains a certain amount of copper.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing aluminum alloy bars, characterized in that, Includes the following steps: Step 1: Weigh the raw materials according to the formula, melt them, remove the slag and stir, adjust the composition to obtain aluminum alloy melt; Step 2: Refine and degas in a refining furnace to obtain refined molten liquid; Step 3: The refined molten liquid is allowed to stand and cast to obtain aluminum alloy ingots. After homogenization annealing, the aluminum alloy ingots are extruded using an extruder to produce aluminum alloy bars. The formulation of the aluminum alloy bar, by weight percentage, includes the following components: Cu: 0.13~0.39%; Mn: 0.12~0.15%; Mg ：0.8~1.0%； Zn: 0.15~0.2%; Zr: 0.05~0.08%; Cr: 0.06~0.07%; Ti: 0.12%; Si: 0.5~0.6%; Fe: ≤0.3%; balance Al; The refining furnace (10) is equipped with a graphite stirring head (12) and a hollow graphite rod (11) coaxially connected to the graphite stirring head (12); the refining furnace (10) is also equipped with two graphite electrode assemblies, the graphite electrode assembly including a graphite outer tube (22), a hollow insulating rod (21) coaxially arranged with the graphite outer tube (22), and a copper pendulum (26). The graphite outer tube (22) and the hollow insulating rod (21) are rotatably connected by a bearing (24). The upper end of the hollow insulating rod (21) and the channel inside the hollow graphite rod (11) are both connected to a nitrogen source. A copper spring (25) is fixedly installed between the upper end of the copper pendulum (26) and the hollow insulating rod (21). The upper end of the copper spring (25) is located inside the graphite outer tube (22), and the copper pendulum (26) is located below the graphite outer tube (22). Two copper springs (25) are respectively connected to the two poles of the pulse power supply; The graphite stirring head rotates at a speed of 450~500 r / min, and the nitrogen flow rate blown into the molten aluminum alloy by the hollow graphite rod is 1.1~1.8 m³ / min. 3 / h; the nitrogen flow rate blown into the molten aluminum alloy by the hollow insulating rod is greater than the nitrogen flow rate blown into the molten aluminum alloy by the hollow graphite rod, and the difference in flow rate is 0.6~0.7m. 3 / h; the rotational speed of the graphite outer tube is less than that of the graphite stirring head, and the difference between the two rotational speeds is 80~100 r / min; the rotational direction of the graphite outer tube in the first graphite electrode assembly is opposite to that in the second graphite electrode assembly. The pulse power supply has a base output current of 30~35A, a peak value of 310~380A, a pulse frequency of 100~120Hz, and an output current waveform of sawtooth wave.

2. The method for producing aluminum alloy bars according to claim 1, characterized in that: In step 3, the casting temperature is 700~710℃ and the casting speed is 11~12m / min.

3. The method for producing aluminum alloy bars according to claim 1, characterized in that: In step 3, the temperature at the outlet of the extruder is controlled at 535~540℃, and the extruded material is quenched by online water mist cooling.

4. The method for producing aluminum alloy bars according to claim 1, characterized in that: The copper pendulum (26) includes an outer hammer body and a lead hammer body embedded inside the outer hammer body.

5. The method for producing aluminum alloy bars according to claim 1, characterized in that: The lower half of the inner wall of the graphite outer tube (22) is provided with a copper plating layer.

6. The application of aluminum alloy rods in the photovoltaic field, characterized by: The aluminum alloy rod is produced using the aluminum alloy rod production method as described in any one of claims 1 to 5.

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