Aluminum alloy refining process based on ultrasonic degassing

Abstract

The present application relates to the aluminum alloy refining process based on ultrasonic degassing, by introducing the aluminum alloy melt after smelting into the on-line degassing furnace after slagging, inserting the ultrasonic amplitude rod array into the aluminum alloy melt in the on-line degassing furnace, and ultrasonic treating the aluminum alloy solution after slagging, the ultrasonic frequency is 20-37 kHz, the ultrasonic power is 1000-2000 W, and the ultrasonic time is 10-15 min. The ultrasonic amplitude rod array is composed of several ultrasonic amplitude rods arranged in a concentric circle structure, the ultrasonic amplitude rod is vertically inserted into the aluminum alloy melt in the on-line degassing furnace, and the lower end of the ultrasonic amplitude rod is provided with a six-hole metal ring. The present application does not need to add traditional grain refiner and pass through inert gas, achieves good grain refinement effect, the uniformity and degassing effect of the aluminum alloy melt are good, the organization structure in the prepared aluminum alloy bar is more compact, and the mechanical property is better. The degassing time is shorter, and the slagging amount is less.

Description

Technical Field

[0001] This invention relates to an aluminum alloy refining process based on ultrasonic degassing, belonging to the field of aluminum alloy smelting technology. Background Technology

[0002] Ultrasonic degassing machines differ from traditional rotary degassing machines in that their structure includes an ultrasonic transmitter and an ultrasonic probe. In China, an ultrasonic amplitude transformer, which is a type of ultrasonic probe, is commonly used. The ultrasonic probe is inserted into the molten aluminum, emitting ultrasonic waves into it. When the ultrasonic intensity is sufficiently high, numerous vacuum bubbles can be formed in the molten aluminum. Hydrogen gas in the aluminum is drawn into these vacuum bubbles and escapes the molten aluminum as the bubbles rise, thus achieving the purpose of degassing and refining.

[0003] Ultrasonic degassing machines can also inject inert gas into molten aluminum using an ultrasonic probe. The inert gas helps form vacuum bubbles, and the ultrasound waves break it into smaller, more distinct particles, thus improving the degassing and refining effect. Compared to traditional rotary degassing machines, ultrasonic degassing machines have a shorter degassing time.

[0004] Furthermore, during ultrasonic degassing, there is usually more slag at the bottom of the molten aluminum, especially if argon gas is introduced to assist degassing, which increases surface disturbance and leads to even more slag formation. Moreover, due to the limited range of a single ultrasonic amplitude transformer, the ultrasonic field strength distribution within the molten aluminum in the furnace or degassing box varies significantly, resulting in uneven grain refinement within the molten aluminum. This is unacceptable for aluminum alloy products requiring higher density. Therefore, improvements are needed. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing an aluminum alloy refining process based on ultrasonic degassing. The specific technical solution is as follows:

[0006] The aluminum alloy refining process based on ultrasonic degassing includes the following steps:

[0007] After slag removal, the molten aluminum alloy is introduced into an online degassing furnace. Then, an ultrasonic amplitude transformer array is inserted into the molten aluminum alloy in the online degassing furnace to perform ultrasonic treatment on the slag-removed aluminum alloy solution. The ultrasonic frequency is 20-37kHz, the ultrasonic power is 1000-2000W, and the ultrasonic time is 10-15min.

[0008] In a further improvement, the ultrasonic amplitude transformer array consists of several ultrasonic amplitude transformers arranged in a concentric circle structure. The ultrasonic amplitude transformers are driven by an ultrasonic transmitter to generate ultrasonic waves. The ultrasonic amplitude transformers extend vertically into the molten aluminum alloy in the online degassing furnace. A six-hole metal ring is installed at the lower end of the ultrasonic amplitude transformer.

[0009] A further improvement is that, along any axial section of the ultrasonic amplitude transformer array, the trajectory of the six-hole metal ring projected onto that axial section is M-shaped.

[0010] Further improvements include ensuring that the temperature of the aluminum alloy solution is not lower than 740℃ during ultrasonic treatment.

[0011] In a further improvement, the six-hole metal ring includes seven hexagonal ring units. The inner ring of each hexagonal ring unit is a circular structure, and the outer ring of each hexagonal ring unit is a regular hexagonal structure. Six hexagonal ring units form a ring structure, and the seventh hexagonal ring unit is located in the center of the ring structure. The center of the seventh hexagonal ring unit is fitted onto the lower end of the ultrasonic amplitude transformer and is fixedly connected. The seven hexagonal ring units are adjacent to each other and connected as a whole.

[0012] In a further improvement, the hexagonal ring unit includes a hollow outer shell, inside which is a lead ball filling chamber, which is filled with lead balls with a particle size of 5 to 10 mm.

[0013] In a further improvement, the distance between the lower end of the ultrasonic amplitude transformer in the ultrasonic amplitude transformer array and the bottom of the online degassing furnace is x, and the distance between the liquid surface of the aluminum alloy melt and the bottom of the online degassing furnace is y, where x / y = 1 / 7, 1 / 2 or 5 / 7.

[0014] When x / y = 1 / 7, the corresponding ultrasonic frequency of the ultrasonic amplitude transformer 21 is 20kHz and the ultrasonic power is 2000W.

[0015] When x / y = 1 / 2, the ultrasonic frequency of the ultrasonic amplitude transformer 21 is 25kHz and the ultrasonic power is 1000W.

[0016] When x / y = 5 / 7, the corresponding ultrasonic frequency of the ultrasonic amplitude transformer 21 is 37kHz and the ultrasonic power is 1600W.

[0017] In a further improvement, the online degassing furnace adopts electromagnetic induction heating, and four sets of electromagnetic induction coil units are sleeved on the outside of the online degassing furnace. The electromagnetic induction coil units are arranged at equal intervals along the axial direction of the online degassing furnace.

[0018] In a further improvement, the electromagnetic induction coil units are activated sequentially from bottom to top;

[0019] When the electromagnetic induction coil unit of the first group is energized, electromagnetic induction heating is performed. When the molten aluminum alloy in the inner area of ​​the electromagnetic induction coil unit is heated to 810-820°C, heating is stopped immediately and delayed for 20-30 seconds.

[0020] When the electromagnetic induction coil unit of the second group is energized, electromagnetic induction heating is performed. When the electromagnetic induction coil unit heats the aluminum alloy melt in its internal area to 810-820°C, heating is immediately stopped and delayed for 20-30 seconds.

[0021] When the electromagnetic induction coil unit of the third group is energized, electromagnetic induction heating is performed. When the electromagnetic induction coil unit heats the aluminum alloy melt in its internal area to 810-820°C, heating is immediately stopped and delayed for 20-30 seconds.

[0022] When the electromagnetic induction coil unit of the fourth group is energized, electromagnetic induction heating is performed. When the molten aluminum alloy in the inner area of ​​the electromagnetic induction coil unit is heated to 810-820°C, heating is stopped immediately and delayed for 20-30 seconds.

[0023] The above constitutes one heating cycle, which is repeated continuously.

[0024] Further improvements involve introducing the refined aluminum alloy molten metal into a hydraulic die-casting machine, where it is die-cast into aluminum alloy bars using molds.

[0025] The beneficial effects of this invention are:

[0026] 1. The aluminum alloy refining process based on ultrasonic degassing described in this invention further optimizes and improves the existing ultrasonic degassing process. It achieves a good grain refinement effect without the need to add traditional grain refiners and introduce inert gas. The aluminum alloy melt has good uniformity and degassing effect, and the resulting aluminum alloy rod has a denser microstructure and better mechanical properties.

[0027] 2. The degassing refining process of the present invention has a shorter degassing time and less slag, making it more suitable for the early smelting of high-performance aluminum alloy products. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the axial distribution of the ultrasonic amplitude transformer array in the online degassing furnace described in this invention;

[0029] Figure 2 This is a schematic diagram of the radial distribution of the ultrasonic amplitude transformer array within the online degassing furnace described in this invention;

[0030] Figure 3 This is a schematic diagram of the structure of the six-hole metal ring described in this invention;

[0031] Figure 4 for Figure 3 AA view;

[0032] Figure 5 This is a schematic diagram of the arrangement of the six-hole metal rings in Comparative Example 3. Detailed Implementation

[0033] 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.

[0034] 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.

[0035] Example 1

[0036] The aluminum alloy refining process based on ultrasonic degassing includes the following steps:

[0037] After slag removal, the molten aluminum alloy is introduced into the online degassing furnace 10, such as... Figure 1 As shown, the ultrasonic amplitude transformer array is then inserted into the molten aluminum alloy in the online degassing furnace 10 to perform ultrasonic treatment on the aluminum alloy solution after slag removal. The ultrasonic frequency is 20-37kHz, the ultrasonic power is 1000-2000W, and the ultrasonic time is 10-15min.

[0038] Specifically: such as Figures 1-4 As shown, the ultrasonic amplitude transformer array consists of several ultrasonic amplitude transformers 21 (purchased from Dongguan Branson Ultrasonic Equipment Co., Ltd., non-ventilated type) arranged in a concentric circle structure, as shown. Figure 2 As shown. The ultrasonic amplitude transformer 21 is driven by the ultrasonic transmitter 20 to generate ultrasonic waves. The ultrasonic amplitude transformer 21 extends vertically into the molten aluminum alloy in the online degassing furnace 10. A six-hole metal ring 22 is installed at the lower end of the ultrasonic amplitude transformer 21.

[0039] Along any axial section of the ultrasonic amplitude transformer array, the trajectory of the projected position of the six-hole metal ring 22 on that axial section is M-shaped, as shown below. Figure 1 As shown in the image.

[0040] The six-hole metal ring 22 includes seven hexagonal ring units 221. The inner ring of each hexagonal ring unit 221 is circular, and the outer ring is regular hexagonal. Six hexagonal ring units 221 form a ring structure, and the seventh hexagonal ring unit 221 is located in the center of the ring structure. The center of the seventh hexagonal ring unit 221 is fitted onto the lower end of the ultrasonic amplitude transformer 21 and is fixedly connected. The seven hexagonal ring units 221 are adjacent to each other and connected as a whole.

[0041] The hexagonal ring unit 221 includes a hollow outer shell 2211, and a lead ball filling chamber 2212 is provided inside the hollow outer shell 2211. The lead ball filling chamber 2212 is filled with lead balls with a particle size of 5 to 10 mm.

[0042] The distance between the lower end of the ultrasonic amplitude transformer 21 in the ultrasonic amplitude transformer array and the bottom of the online degassing furnace 10 is x, and the distance between the liquid surface of the aluminum alloy melt and the bottom of the online degassing furnace 10 is y, where x / y = 1 / 7, 1 / 2 or 5 / 7.

[0043] When x / y = 1 / 7, the corresponding ultrasonic frequency of the ultrasonic amplitude transformer 21 is 20kHz and the ultrasonic power is 2000W.

[0044] When x / y = 1 / 2, the corresponding ultrasonic frequency of the ultrasonic amplitude transformer 21 is 25kHz and the ultrasonic power is 1000W.

[0045] When x / y = 5 / 7, the corresponding ultrasonic frequency of the ultrasonic amplitude transformer 21 is 37kHz and the ultrasonic power is 1600W.

[0046] The online degassing furnace 10 uses electromagnetic induction heating. Four sets of electromagnetic induction coil units 30 are sleeved on the outside of the online degassing furnace 10. The electromagnetic induction coil units 30 are arranged at equal intervals along the axial direction of the online degassing furnace 10.

[0047] The electromagnetic induction coil unit 30 is activated sequentially from bottom to top;

[0048] When the electromagnetic induction coil unit 30 of the first group is energized, electromagnetic induction heating is performed. When the electromagnetic induction coil unit 30 heats the aluminum alloy melt in its internal area to 810-820°C, heating is immediately stopped and delayed for 20-30 seconds.

[0049] When the electromagnetic induction coil unit 30 of the second group is energized, electromagnetic induction heating is performed. When the electromagnetic induction coil unit 30 heats the aluminum alloy melt in its internal area to 810-820°C, heating is immediately stopped and delayed for 20-30 seconds.

[0050] When the electromagnetic induction coil unit 30 of the third group is energized, electromagnetic induction heating is performed. When the electromagnetic induction coil unit 30 heats the aluminum alloy melt in its internal area to 810-820°C, heating is immediately stopped and delayed for 20-30 seconds.

[0051] When the electromagnetic induction coil unit 30 of the fourth group is energized, electromagnetic induction heating is performed. When the electromagnetic induction coil unit 30 heats the aluminum alloy melt in its internal area to 810-820°C, heating is immediately stopped and delayed for 20-30 seconds.

[0052] The above constitutes one heating cycle, which is repeated continuously.

[0053] The refined aluminum alloy molten metal is introduced into a hydraulic die-casting machine, and aluminum alloy bars are die-cast using molds.

[0054] In this invention, when ultrasonic degassing is used, the degassing time is short. Compared with the traditional rotary degassing machine, the degassing time of ultrasonic degassing can be shortened to 10-15 minutes. In addition, the liquid surface disturbance is small and the slag formation is less.

[0055] In addition, by adding a six-hole metal ring 22, the lead ball inside, along with its structure, will generate strong ultrasonic oscillations, which can refine the grains, promote uniform crystallization, and effectively improve the density and mechanical properties of the microstructure.

[0056] The ultrasonic amplitude transformer array with a special arrangement, plus a six-hole metal ring 22, can quickly degas without introducing inert gas, and does not affect the final density of the aluminum alloy.

[0057] The online degassing furnace 10 is not a conventional holding furnace used in on-site refining; it is simply a regular steel furnace. The molten aluminum alloy is placed inside, and its temperature drops. The electromagnetic induction coil unit 30 continuously replenishes the heat, ensuring that the temperature of the aluminum alloy solution does not fall below 740°C during ultrasonic treatment. By sequentially heating the molten aluminum alloy at different height levels, and utilizing the expansion stress caused by the sudden temperature increase at different levels, as well as the combined effects of gravity and the impact of ultrasonic waves, the density of the aluminum alloy is significantly improved.

[0058] Comparative Example 1

[0059] Using the same number of ultrasonic amplitude transformers 21, with x / y = 1 / 7, degassing was performed in a holding furnace. The temperature of the molten aluminum alloy was stabilized at 740–745℃. The ultrasonic frequency of the ultrasonic amplitude transformers 21 was 20kHz, and the ultrasonic power was 2000W. The final control rod 1 was obtained. The degassing time was 40 min, and the slag production was 7.1 kg / t.

[0060] Comparative Example 2

[0061] Based on Comparative Example 1, the ultrasonic amplitude transformer also allows for air circulation in the center (purchased from Dongguan Branson Ultrasonic Equipment Co., Ltd., air-vented type), using argon as the degassing medium, with a degassing pressure of 0.4 MPa and a degassing flow rate of 2 m³ / s. 3 / h.

[0062] Comparative Example 3

[0063] In this example, along any axial section of the ultrasonic amplitude transformer array, the trajectory of the projected position of the six-hole metal ring 22 at that axial section is stepped, as shown below. Figure 5 As shown in the figure; the rest is the same as in Example 1.

[0064] Comparative Example 4

[0065] In this example, the outer ring of the hexagonal ring unit 221 is circular, and the rest is the same as in Embodiment 1.

[0066] Comparative Example 5

[0067] In this example, all ultrasonic amplitude transformers have an ultrasonic frequency of 20kHz and an ultrasonic power of 2000W. Everything else is the same as in Example 1.

[0068] Comparative Example 6

[0069] In this example, all ultrasonic amplitude transformers have an ultrasonic frequency of 37kHz and an ultrasonic power of 1000W. Everything else is the same as in Example 1.

[0070] Comparative Example 7

[0071] In this example, all electromagnetic induction coil units 30 are always activated to maintain the temperature of the aluminum alloy solution at 740–760°C. Everything else is the same as in Example 1.

[0072] Comparative Example 8

[0073] In this example, the hexagonal ring unit 221 is made of a solid shell and is not filled with lead balls. The rest is the same as in Example 1.

[0074] Examples 1 and 8 were labeled according to the "Characteristic Test of Density of Aluminum Alloys", and the results are shown in Table 1:

[0075] Table 1

[0076] Degassing time (min) Slag production (kg / t) <![CDATA[Pinhole degree (number / m 2 )]]> Tensile strength of aluminum foil (MPa) Example 1 10 2.2 1 85 Comparative Example 1 40 7.1 / / Comparative Example 2 30 7.3 / / Comparative Example 3 15 3.9 96 79 Comparative Example 4 12 5.0 13 83 Comparative Example 5 10 4.7 230 76 Comparative Example 6 17 3.5 315 71 Comparative Example 7 11 2.3 252 75 Comparative Example 8 12 2.2 191 77

[0077] Tests for Characterizing the Density of Aluminum Alloys

[0078] Aluminum alloy rods are hot-rolled, cold-rolled, and foil-rolled to obtain foil-rolled coils (referred to as aluminum foil) with a thickness of 0.005mm. The pinholes are tested using an aluminum foil pinhole tester, which is used to count the number of pinholes with a diameter of 0.3mm and above.

[0079] It is well known in the art that fewer pinholes indicate better mechanical properties of aluminum foil, finer and more uniform grains in the rod, and a denser microstructure.

[0080] In the above embodiments, all aluminum alloys used are 8006 aluminum alloys.

[0081] In the refining process of this invention, there is no need to add traditional grain refiners, achieving a good grain refinement effect. The aluminum alloy melt has good uniformity and degassing effect, and the resulting aluminum alloy rod has a denser microstructure and better mechanical properties. If it is made into aluminum foil, it has high airtightness, is not easy to break, and can meet higher usage requirements.

[0082] The above description is only 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. An aluminum alloy refining process based on ultrasonic degassing, characterized in that... Includes the following steps: After slag removal, the molten aluminum alloy is introduced into an online degassing furnace (10). Then, an ultrasonic amplitude transformer array is inserted into the molten aluminum alloy in the online degassing furnace (10) to perform ultrasonic treatment on the slag-removed aluminum alloy solution. The ultrasonic frequency is 20~37kHz, the ultrasonic power is 1000~2000W, and the ultrasonic time is 10~15min. The ultrasonic amplitude transformer array consists of several ultrasonic amplitude transformers (21) arranged in a concentric circle structure. The ultrasonic amplitude transformers (21) are driven by an ultrasonic transmitter (20) to generate ultrasonic waves. The ultrasonic amplitude transformers (21) extend vertically into the molten aluminum alloy in the online degassing furnace (10). A six-hole metal ring (22) is installed at the lower end of the ultrasonic amplitude transformers (21). Along any axial section of the ultrasonic amplitude transformer array, the trajectory of the six-hole metal ring (22) at the projection position of that axial section is M-shaped.

2. The aluminum alloy refining process based on ultrasonic degassing according to claim 1, characterized in that: When the aluminum alloy solution is subjected to ultrasonic treatment, the temperature of the aluminum alloy solution shall not be lower than 740℃.

3. The aluminum alloy refining process based on ultrasonic degassing according to claim 1, characterized in that: The six-hole metal ring (22) includes seven hexagonal ring units (221). The inner ring of the hexagonal ring unit (221) is a circular structure, and the outer ring of the hexagonal ring unit (221) is a regular hexagonal structure. Six hexagonal ring units (221) form a ring structure, and the seventh hexagonal ring unit (221) is located in the center of the ring structure. The center of the seventh hexagonal ring unit (221) is fitted onto the lower end of the ultrasonic amplitude transformer (21) and fixedly connected. The seven hexagonal ring units (221) are adjacent to each other and connected as a whole.

4. The aluminum alloy refining process based on ultrasonic degassing according to claim 3, characterized in that: The hexagonal ring unit (221) includes a hollow shell (2211), and a lead ball filling chamber (2212) is provided inside the hollow shell (2211). The lead ball filling chamber (2212) is filled with lead balls with a particle size of 5~10mm.

5. The aluminum alloy refining process based on ultrasonic degassing according to claim 4, characterized in that: The distance between the lower end of the ultrasonic amplitude transformer (21) in the ultrasonic amplitude transformer array and the bottom of the online degassing furnace (10) is x, and the distance between the liquid surface of the aluminum alloy melt and the bottom of the online degassing furnace (10) is y, x / y=1 / 7, 1 / 2 or 5 / 7. When x / y=1 / 7, the ultrasonic frequency of the corresponding ultrasonic amplitude transformer (21) is 20kHz and the ultrasonic power is 2000W. When x / y=1 / 2, the ultrasonic frequency of the corresponding ultrasonic amplitude transformer (21) is 25kHz and the ultrasonic power is 1000W. When x / y=5 / 7, the ultrasonic frequency of the corresponding ultrasonic amplitude transformer (21) is 37kHz and the ultrasonic power is 1600W.

6. The aluminum alloy refining process based on ultrasonic degassing according to claim 1, characterized in that: The online degassing furnace (10) is heated by electromagnetic induction. Four sets of electromagnetic induction coil units (30) are installed on the outside of the online degassing furnace (10). The electromagnetic induction coil units (30) are arranged at equal intervals along the axial direction of the online degassing furnace (10).

7. The aluminum alloy refining process based on ultrasonic degassing according to claim 6, characterized in that: The electromagnetic induction coil units are activated sequentially from bottom to top; When the electromagnetic induction coil unit of the first group is energized, electromagnetic induction heating is performed. When the electromagnetic induction coil unit of the first group heats the aluminum alloy melt in its internal area to 810~820℃, heating is stopped immediately and delayed for 20~30s. When the electromagnetic induction coil unit of the second group is energized, electromagnetic induction heating is performed. When the electromagnetic induction coil unit of the second group heats the aluminum alloy melt in its internal area to 810~820℃, heating is stopped immediately and delayed for 20~30s. When the electromagnetic induction coil unit of the third group is energized, electromagnetic induction heating is performed. When the electromagnetic induction coil unit of the third group heats the aluminum alloy melt in its internal area to 810~820℃, heating is stopped immediately and delayed for 20~30s. When the electromagnetic induction coil unit of the fourth group is energized, electromagnetic induction heating is performed. When the electromagnetic induction coil unit of the fourth group heats the aluminum alloy melt in its internal area to 810~820℃, heating is stopped immediately and delayed for 20~30s. The above constitutes one heating cycle, which is repeated continuously.

8. The aluminum alloy refining process based on ultrasonic degassing according to claim 1, characterized in that: The refined aluminum alloy molten metal is introduced into a hydraulic die-casting machine, and aluminum alloy bars are die-cast using molds.

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