A double-action serial circulation high-purity aluminum melt low-pressure casting device and preparation method

Abstract

The present invention provides a dual-action serial circulation high-purity aluminum melt low-pressure casting device and preparation method. The present invention can complete the purification and fine-graining preparation of aluminum alloy melt in a gas-fired heating furnace, and realize the low-pressure casting of complex structural metal products in a low-pressure casting furnace. The gas-fired heating furnace and the low-pressure casting furnace do not need to be mechanically transferred. By monitoring the melt level and opening and closing the automatic angle meter and the double-furnace stop plugs, the gas-fired heating furnace can dynamically replenish the aluminum alloy melt in the low-pressure casting furnace. This dynamic replenishment causes little fluctuation in the surface of the aluminum alloy melt in the low-pressure casting furnace, and does not generate significant turbulence, air entrainment, or slag inclusions. At the same time, the replenished aluminum alloy melt is of high quality and contains less oxidized slag inclusions, greatly improving the metallurgical quality of the melt.

Description

Technical Field

[0001] The present invention belongs to the field of casting forming technology and technology of aluminum alloy metal products, and particularly relates to a double-action serial circulation high-purity aluminum melt low-pressure casting device and a preparation method. Background Art

[0002] Aluminum alloys, with their low density, high specific strength and stiffness, excellent corrosion resistance, and superior processing properties, are widely used in aerospace, military equipment, rail transportation, new energy vehicles, and the chemical industry. Compared to other forming processes such as forging and welding, casting allows for the integrated manufacture of complex structures, resulting in significant material and structural weight reductions and significant economic benefits.

[0003] Compared to traditional sand casting, plaster casting, and investment shell casting, the counter-gravity casting process allows for sequential solidification of the alloy melt from bottom to top, resulting in a superior metallurgical structure and significantly improved mechanical properties of the resulting castings. Counter-gravity casting processes include vacuum casting, low-pressure casting, differential pressure casting, and pressure-regulated casting. Low-pressure casting accounts for a high proportion of counter-gravity casting applications both domestically and internationally, particularly in the military and automotive sectors. Low-pressure casting is widely used to cast complex structures such as missile hulls, automotive shock towers, subframes, and aluminum alloy wheels. During low-pressure casting, a mold (such as a sand mold, metal mold, or other material) is typically placed above a sealed melting furnace. Compressed air is introduced into the furnace, applying a certain pressure to the molten metal surface. Under the pressure of the compressed air, the molten metal flows from the bottom up through a riser tube, filling the mold and solidifying sequentially under the pressure. The low-pressure casting process has good shrinkage compensation, dense casting structure, and is easy to cast large and complex thin-walled structure castings. No riser is required during the casting process, and the metal recovery rate can be as high as over 90%. The entire casting process has little pollution to the environment and is easy to automate.

[0004] However, the current low-pressure casting process for complex aluminum alloy castings, such as those for military equipment and automotive wheel hubs, typically relies on a single-furnace melting and casting process. This method results in long production cycles, low forming efficiency, and high manufacturing costs. Prior art also reports the use of a dual-furnace, parallel circulation low-pressure casting process, where one furnace performs low-pressure casting while the other melts the charge. Once low-pressure casting is complete in one furnace, a transfer mechanism transfers the melted furnace body to the bottom of the riser tube, where low-pressure casting is repeated in a reciprocating cycle. This dual-furnace refrigerator circulation method is only a superposition of single-furnace melting and casting. It cannot achieve dynamic adjustment of the aluminum alloy melt during the low-pressure casting process, and does not fundamentally solve the process problems of low production efficiency and high manufacturing cost in the low-pressure casting forming process; and the existing publicly reported dual-furnace designs are mostly structurally optimized from the perspective of production efficiency of melting and low-pressure casting, without considering the purification of the alloy melt and grain refinement treatment. As a result, the existing dual-furnace low-pressure casting device has a low batch production qualification rate, coarse cast grain structure, poor metallurgical quality and low mechanical properties when producing batch aluminum alloy metal products. There are still many problems that need to be solved in actual use. Summary of the Invention

[0005] In order to solve the process difficulties of the existing double-furnace low-pressure casting device when producing batches of aluminum alloy metal products, such as the inability to dynamically replenish the aluminum alloy melt in the low-pressure casting furnace (that is, the aluminum alloy melt in the low-pressure casting furnace cannot be replenished in real time during the low-pressure casting process), low production efficiency, high manufacturing cost, low batch production qualification rate, coarse cast grain structure, poor metallurgical quality and low mechanical properties; the present invention provides a double-action serial circulation high-purity aluminum melt low-pressure casting device and a preparation method. The double-action serial circulation high-purity aluminum melt low-pressure casting device and preparation method of the present invention can realize the double-action serial circulation of the gas-fired heating furnace and the low-pressure casting furnace, that is, the aluminum alloy melt in the low-pressure casting furnace can be replenished in real time during the low-pressure casting process; specifically, the present invention can complete the purification and fine-grained preparation of the aluminum alloy melt in the gas-fired heating furnace, and realize the low-pressure casting of complex structure metal products in the low-pressure casting furnace, and the gas-fired heating furnace and the low-pressure casting furnace do not need to be mechanically transferred. The gas-fired heating furnace can dynamically replenish the aluminum alloy melt in the low-pressure casting furnace through the monitoring of the melt level and the opening and closing of the automatic angle meter and the double-furnace stop plugs. The dynamic replenishment has little effect on the fluctuation of the surface of the aluminum alloy melt in the low-pressure casting furnace, and will not produce obvious turbulence, air entrainment, or slag inclusions. At the same time, the replenished aluminum alloy melt is of high quality and has a low content of oxidized slag inclusions, which greatly improves the metallurgical quality of the melt.

[0006] The use of the double-action serial circulation high-purity aluminum melt low-pressure casting device and preparation method of the present invention can significantly improve the production efficiency, batch production qualification rate and metallurgical quality of aluminum alloy metal products, while significantly reducing manufacturing costs; the double-action serial circulation high-purity aluminum melt low-pressure casting device and preparation method of the present invention also have the characteristics of low environmental pollution, strong material versatility, solid hydrogen content can be controlled below 0.10ml / 100gAl, the average grain size of the cast structure is stable below 50μm, the oxide film meets the GB / T6519-2013 standard Level I, and the single-point oxide film area is ≤2mm², the production cost is reduced by more than 10%, the production cycle is shortened by more than 15%, and the batch production qualification rate can be increased to more than 90%.

[0007] The object of the present invention is achieved through the following technical solutions:

[0008] A double-action serial circulation high-purity aluminum melt low-pressure casting device, wherein the low-pressure casting device includes a gas heating furnace and a low-pressure casting furnace; the gas heating furnace is arranged on one side of the low-pressure casting furnace, and the gas heating furnace and the low-pressure casting furnace are connected through a double furnace stop plug;

[0009] The gas heating furnace includes a master alloy feeder, a gas heater, a melt feeding filter, a gas heating furnace level gauge and a melt extraction and pressure pump;

[0010] The master alloy feeder and the gas heater are arranged on the side wall of the gas heating furnace; the melt feeding filter is arranged on the top of the gas heating furnace; the gas heating furnace level gauge is arranged on the top of the gas heating furnace and extends into the interior of the gas heating furnace; the melt extraction pressure pump is arranged inside the gas heating furnace;

[0011] The low-pressure casting furnace includes an automatic oscillating angle meter, a low-pressure casting furnace heater, a pressurizing pipe, a liquid riser, a low-pressure casting furnace liquid level gauge and an inert gas inlet;

[0012] The low-pressure casting furnace heater and inert gas inlet are arranged on the side wall of the low-pressure casting furnace; the pressurizing pipe is arranged on the top of the low-pressure casting furnace; the automatic swing angle meter, rising liquid pipe and low-pressure casting furnace liquid level gauge are arranged on the top of the low-pressure casting furnace and extend to the interior of the low-pressure casting furnace; the automatic swing angle meter is connected to the double furnace stop plug.

[0013] The present invention also provides a method for preparing a double-action serial circulation high-purity aluminum melt. The method is implemented based on the above-mentioned double-action serial circulation high-purity aluminum melt low-pressure casting device, and the method comprises the following steps:

[0014] 1) Charging and melting: Add pure aluminum melt into the gas-fired heating furnace through the melt feeding filter, prepare the master alloy according to the alloy composition, and add the master alloy into the gas-fired heating furnace through the master alloy feeder; turn on the gas heater and adjust the temperature in the gas-fired heating furnace until the master alloy is completely melted;

[0015] 2) Temperature adjustment and static placement: Start the low-pressure casting furnace heater, adjust the temperature inside the low-pressure casting furnace to a certain temperature range and keep it warm for a certain period of time; open the inert gas inlet device, and introduce inert gas into the low-pressure casting furnace to provide inert atmosphere protection for the aluminum alloy melt;

[0016] 3) Melt double-action serial circulation and low-pressure casting: Before low-pressure casting, detect the content of aluminum alloy melt in the gas heating furnace and low-pressure casting furnace:

[0017] 3-1) When the gas-fired heating furnace level gauge detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is higher than a first threshold value, and the low-pressure casting furnace level gauge detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is higher than a second threshold value, the automatic swing angle meter is adjusted to close the double furnace stop plugs, and the melt extraction pressure pump is turned off at the same time; the pressure pipe is opened to introduce high-pressure gas into the low-pressure casting furnace; the riser pipe is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to achieve casting and forming of aluminum alloy metal products;

[0018] 3-2) When the gas heating furnace level gauge detects that the liquid level of the aluminum alloy melt in the gas heating furnace is higher than the first threshold value, and the low-pressure casting furnace level gauge detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is lower than the second threshold value, the automatic swing angle meter is adjusted to open the double-furnace stop plugs, and the melt extraction and pressure pump is turned on at the same time to achieve double-action serial circulation of the aluminum alloy melt; when the low-pressure casting furnace level gauge detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is higher than the third threshold value, the automatic swing angle meter is adjusted to close the double-furnace stop plugs, and the melt extraction and pressure pump is turned off at the same time; the pressure pipe is opened to introduce high-pressure gas into the low-pressure casting furnace; the liquid riser is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to achieve casting and forming of aluminum alloy metal products;

[0019] 3-3) When the gas-fired heating furnace liquid level gauge detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is lower than the first threshold, pure aluminum melt and master alloy are continued to be added to the gas-fired heating furnace to prepare the melt, the automatic swing angle meter is adjusted to close the double furnace stop plugs, and the melt extraction and pressure pump is turned off at the same time; after the aluminum alloy melt preparation is completed and the gas-fired heating furnace liquid level gauge detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is higher than the first threshold, step 3-1) or step 3-2) is repeated to achieve the casting of the aluminum alloy metal product;

[0020] Among them, the first threshold is 1 / 5 of the effective total height of the gas heating furnace body; the second threshold is 1 / 4 of the effective total height of the low-pressure casting furnace body; and the third threshold is the effective total height of the low-pressure casting furnace body.

[0021] Beneficial effects of the present invention:

[0022] The present invention provides a double-action serial circulation high-purity aluminum melt low-pressure casting device and preparation method. Compared with a single-furnace low-pressure casting device, the double-furnace design adopted in the present invention can dynamically replenish the aluminum alloy melt in the low-pressure casting furnace before low-pressure casting or after pressure relief, rather than requiring a new furnace body to be replaced during single-furnace low-pressure casting. Compared with the existing publicly reported double-furnace low-pressure casting device, the present invention realizes the dynamic replenishment of the aluminum alloy melt in the low-pressure casting furnace by the gas-fired heating furnace through the monitoring of the melt level and the opening and closing of the automatic angle meter and the double-furnace stop plug, and then realizes the real-time double-action serial circulation of the double furnaces, rather than the existing double-furnace low-pressure casting device which needs to complete 2-3 casting cycles before opening the plugging rod to achieve melt replenishment.

[0023] The double-action serial circulation operation of the present invention causes little fluctuation on the surface of the melt when replenishing the melt, and does not generate obvious turbulence, air entrainment, or slag inclusions, which greatly improves the metallurgical quality of the melt. The design of the low-pressure casting device of the present invention can achieve dynamic replenishment of the melt without any transfer mechanism, which is significantly different from the currently publicly reported double-furnace low-pressure casting devices. The low-pressure casting device of the present invention has higher production efficiency, and the production cycle can be shortened by more than 15%. The double-action serial circulation high-purity aluminum melt low-pressure casting device of the present invention can also include a powder refining agent inlet and an argon generator, both of which can achieve high-purity preparation of the melt in a gas-fired heating furnace, so that the obtained oxide film can meet the GB / T6519-2013 standard Level I, and the single-point oxide film area is ≤2mm². The dual-action, serial-circulation, high-purity aluminum melt low-pressure casting apparatus of the present invention may also include a grain-refining powder inlet and an ultrasonic vibrator. These two devices continuously break down as-cast dendrites during the smelting stage, generating a large number of TiB2, Al3Ti, AlB2, Al3Zr, and Al3Sc nucleation particles (see Equations 1 to 5) through in-situ reactions within the melt. These particles significantly refine the as-cast grain structure, transforming the grain morphology from dendrites to fine equiaxed crystals. The solid hydrogen content can be controlled below 0.10 ml / 100 g Al, and the average grain size of the as-cast structure remains stable below 50 μm, significantly improving the overall mechanical properties of aluminum alloy metal products. The dual-action, serial-circulation, high-purity aluminum melt low-pressure casting apparatus of the present invention may also include a liquid melt densitometer, which can rapidly detect the chemical composition of the aluminum alloy melt. The dual-action serial circulation high-purity aluminum melt low-pressure casting device of the present invention can also include a furnace gas exhaust pipe for discharging waste smoke and exhaust gas from the gas heating furnace, and the furnace gas exhaust pipe is arranged on the outside of the lining of the low-pressure casting furnace. Combined with the lining designed with a gradient composite structure material, it can provide excellent thermal insulation, reduce production costs by more than 10%, and increase the batch production qualification rate to more than 90%. The dual-action serial circulation high-purity aluminum melt low-pressure casting device and preparation method of the present invention have low manufacturing costs, low environmental pollution, and strong material versatility. They can significantly improve the batch production qualification rate of complex structural metal products in the aerospace and automotive fields.

[0024] BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of a double-action serial circulation high-purity aluminum melt low-pressure casting device according to a preferred embodiment of the present invention.

[0026] Figure numerals: 1 is an argon generator; 2 is an ultrasonic vibrator; 3 is a powder refining agent inlet; 4 is a grain refining powder inlet; 5 is an intermediate alloy feeder; 6 is a gas heater; 7 is a melt feeding filter; 8 is a gas heating furnace level gauge; 9 is an automatic slag skimmer; 10 is a mechanical stirrer; 11 is a furnace gas exhaust pipe; 12 is a double furnace stop plug; 13 is an automatic angle meter; 14 is a low-pressure casting furnace heater; 15 is a pressurizing pipe; 16 is a liquid riser; 17 is a liquid melt density meter; 18 is a low-pressure casting furnace level gauge; 19 is a furnace gas exhaust brake ball valve; 20 is an inert gas inlet; 21 is a low-pressure casting furnace side end thermocouple; 22 is a low-pressure casting furnace bottom end thermocouple; 23 is the furnace lining of the low-pressure casting furnace; 24 is the furnace lining of the gas heating furnace; 25 is a melt extraction pressure pump.

[0027] Figure 2 This is a schematic diagram of the working principle of the double-action serial circulation high-purity aluminum melt low-pressure casting device of the present invention.

[0028] Figure 3 This is a schematic diagram of the furnace lining structure of the double-action serial circulation high-purity aluminum melt low-pressure casting device of the present invention.

[0029] Figure 4 This is a schematic diagram of the liquid level control of the double-action serial circulation of the gas heating furnace and the low-pressure casting furnace in the double-action serial circulation high-purity aluminum melt low-pressure casting device of the present invention.

[0030] Figure 5 This is a schematic diagram of the refining and degassing principle of the double-action serial circulation high-purity aluminum melt low-pressure casting device of the present invention.

[0031] Figure 6 The present invention provides comparative test results of solid hydrogen content in multiple furnace batches of a single-furnace low-pressure casting device, an existing publicly reported dual-furnace low-pressure casting device, and a dual-action serial circulation high-purity aluminum melt low-pressure casting device as shown in Example 2.

[0032] Figure 7 This is a schematic diagram of the aluminum alloy wheel hub prepared by the low-pressure casting device of Example 2.

[0033] Figure 8 This is a schematic diagram of the actual aluminum alloy compartment shell prepared by the low-pressure casting device of Example 3.

[0034] Figure 9 This is the density curve of A356 aluminum alloy used by the liquid melt density meter of the double-action serial circulation high-purity aluminum melt low-pressure casting device in Example 4. DETAILED DESCRIPTION

[0035] As mentioned above, the present invention provides a double-action serial circulation high-purity aluminum melt low-pressure casting device, wherein the low-pressure casting device includes a gas heating furnace and a low-pressure casting furnace; the gas heating furnace is arranged on one side of the low-pressure casting furnace, and the gas heating furnace and the low-pressure casting furnace are connected through a double-furnace stop plug 12;

[0036] The gas-fired heating furnace includes an intermediate alloy feeder 5, a gas heater 6, a melt feeding filter 7, a gas-fired heating furnace level gauge 8, and a melt extraction and pressure pump 25; the intermediate alloy feeder 5 and the gas heater 6 are arranged on the side wall of the gas-fired heating furnace; the melt feeding filter 7 is arranged on the top of the gas-fired heating furnace; the gas-fired heating furnace level gauge 8 is arranged on the top of the gas-fired heating furnace and extends into the interior of the gas-fired heating furnace; the melt extraction and pressure pump 25 is arranged inside the gas-fired heating furnace;

[0037] The low-pressure casting furnace includes an automatic oscillating angle meter 13, a low-pressure casting furnace heater 14, a pressure pipe 15, a rising liquid pipe 16, a low-pressure casting furnace liquid level meter 18 and an inert gas inlet 20; the low-pressure casting furnace heater 14 and the inert gas inlet 20 are arranged on the side wall of the low-pressure casting furnace; the pressure pipe 15 is arranged on the top of the low-pressure casting furnace; the automatic oscillating angle meter 13, the rising liquid pipe 16 and the low-pressure casting furnace liquid level meter 18 are arranged on the top of the low-pressure casting furnace and extend to the interior of the low-pressure casting furnace; the automatic oscillating angle meter 13 is connected to the double furnace stop plug 12.

[0038] According to an embodiment of the present invention, the gas-fired heating furnace further includes an argon generator 1, an ultrasonic vibrator 2, a powder refining agent inlet 3 and a grain refining powder inlet 4; the argon generator 1 and the ultrasonic vibrator 2 are arranged at the bottom of the gas-fired heating furnace; the powder refining agent inlet 3 and the grain refining powder inlet 4 are arranged on the side wall of the gas-fired heating furnace.

[0039] According to an embodiment of the present invention, the gas-fired heating furnace further comprises an automatic skimmer 9 and a mechanical stirrer 10 ; the automatic skimmer 9 and the mechanical stirrer 10 are arranged on the top of the gas-fired heating furnace and extend into the interior of the gas-fired heating furnace.

[0040] According to an embodiment of the present invention, the gas-fired heating furnace further comprises a furnace lining 24 of the gas-fired heating furnace.

[0041] According to an embodiment of the present invention, the low-pressure casting furnace further includes a furnace lining 23 of the low-pressure casting furnace.

[0042] According to an embodiment of the present invention, the gas heating furnace further includes a furnace gas exhaust pipe 11; the inlet of the furnace gas exhaust pipe 11 is arranged at the top of the gas heating furnace, and the furnace gas exhaust pipe 11 is arranged on the outside of the furnace lining 23 of the low-pressure casting furnace.

[0043] According to an embodiment of the present invention, the low-pressure casting furnace includes a liquid melt density meter 17, a low-pressure casting furnace side end thermocouple 21 and a low-pressure casting furnace bottom end thermocouple 22; the low-pressure casting furnace side end thermocouple 21 is arranged on the side wall of the low-pressure casting furnace; the liquid melt density meter 17 is arranged on the top of the low-pressure casting furnace and extends to the interior of the low-pressure casting furnace; the low-pressure casting furnace bottom end thermocouple 22 is arranged at the bottom of the low-pressure casting furnace.

[0044] According to an embodiment of the present invention, the low-pressure casting furnace further includes a furnace gas exhaust brake ball valve 19 ; the furnace gas exhaust brake ball valve 19 is disposed at the outlet of the furnace gas exhaust duct 11 .

[0045] According to an embodiment of the present invention, the argon generator 1 and the powder refining agent inlet 3 are used to refine and degas the aluminum alloy melt; illustratively, the argon generator 1 is turned on, the powder refining agent inlet 3 is opened, and the powder refining agent is pressed into the gas-fired heating furnace to complete the refining and degassing process of the aluminum alloy melt in the gas-fired heating furnace. The number of the argon generators 1 is 3-5, and the distance between them is ≥450mm. The flow rate of the argon gas introduced into the argon generator 1 is 2.0L·min -1 -4.5L·min -1 The number of the powder refining agent inlet devices 3 is 2-4, and the distance between them is ≥500mm. The powder refining agent inlet devices 3 are arranged on the side wall of the gas-fired heating furnace and close to the bottom of the gas-fired heating furnace; such a position setting can ensure that the powder refining agent pressed through the powder refining agent inlet device 3 is directly pressed into the interior of the aluminum alloy melt, avoiding the splashing of the aluminum alloy melt due to the addition of the powder refining agent and increasing the content of oxidized slag in the melt.

[0046] According to an embodiment of the present invention, the powder refining agent includes Na3AlF6, KCl, CaCl2, TiO2, C2Cl6 and Na2SiF6; wherein, the mass of Na3AlF6 accounts for 5%-7% of the total mass of the powder refining agent, the mass of KCl accounts for 2%-4% of the total mass of the powder refining agent, the mass of TiO2 accounts for 20%-24% of the total mass of the powder refining agent, the mass of C2Cl6 accounts for 50%-52% of the total mass of the powder refining agent, the mass of Na2SiF6 accounts for 4%-6% of the total mass of the powder refining agent, and the balance is CaCl2.

[0047] According to an embodiment of the present invention, the ultrasonic exciter 2 and the grain refining powder feeder 4 are used to refine the grain of the aluminum alloy melt; illustratively, the ultrasonic exciter 2 is turned on, the grain refining powder feeder 4 is opened, and the grain refining powder is pressed into the gas-fired heating furnace to complete the grain refining treatment process of the aluminum alloy melt in the gas-fired heating furnace. The number of the ultrasonic exciters 2 is 2-4, and the distance between each other is ≥400mm. The ultrasonic excitation frequency emitted by the ultrasonic exciter 2 is 18kHz-30kHz, the ultrasonic excitation amplitude is 25μm-75μm, the ultrasonic excitation mode is a pulse mode, and the duty cycle is 65%-80%. The number of the grain refining powder feeders 4 is 1-3, and the distance between each other is ≥500mm. The grain refining powder inlet device 4 is arranged on the side wall of the gas-fired heating furnace and close to the bottom of the gas-fired heating furnace; such a position setting can ensure that the grain refining powder pressed through the grain refining powder inlet device 4 is directly pressed into the interior of the aluminum alloy melt, avoiding splashing of the aluminum alloy melt due to the addition of the grain refining powder and increasing the content of oxidized slag in the melt.

[0048] According to an embodiment of the present invention, the grain refining powder includes K2TiF6, KBF4, K2ZrF6 and Sc2O3; wherein the mass of K2TiF6 accounts for 35%-38% of the total mass of the grain refining powder, the mass of KBF4 accounts for 28%-32% of the total mass of the grain refining powder, the mass of K2ZrF6 accounts for 18%-20% of the total mass of the grain refining powder, and the balance is Sc2O3.

[0049] According to an embodiment of the present invention, compared with existing single-furnace low-pressure casting devices and dual-furnace low-pressure casting devices, the low-pressure casting device of the present invention further adds the functions of high-purity melt preparation and grain refinement. Specifically, the gas-fired heating furnace in the low-pressure casting device of the present invention uses high-purity aluminum melt as the main raw material, and through alloy composition configuration and the addition of corresponding master alloys, further combined with a powder refining agent and an argon generator to achieve high-purity preparation of the aluminum alloy melt, and combined with a grain refinement powder and an ultrasonic vibrator to achieve grain refinement of the aluminum alloy melt. In particular, the introduction of the grain refinement powder and the ultrasonic vibrator can continuously break up the as-cast dendrites, while facilitating the generation of a large number of TiB2, Al3Ti, AlB2, Al3Zr, and Al3Sc nucleation particles through in-situ reactions within the melt, significantly refining the as-cast grain structure, transforming the grain morphology from dendrites to fine equiaxed crystals, and significantly improving the batch production qualification rate, metallurgical quality, and mechanical properties of metal products.

[0050] According to an embodiment of the present invention, the number of the intermediate alloy feeder 5 is one. The intermediate alloy ingot is added to the gas-fired heating furnace through the intermediate alloy feeder 5; the intermediate alloy needs to be heat-baked before being added to the gas-fired heating furnace. The heat-baking temperature is 200°C-300°C and the heat-baking time is 25min-35min. The purpose of the heat-baking is to remove oil and moisture from the surface of the intermediate alloy and improve the quality of the aluminum alloy melt. The intermediate alloy feeder 5 is set on the side wall of the gas-fired heating furnace, and the distance between it and the top of the gas-fired heating furnace is ≥300mm. The setting of the position of the intermediate alloy feeder 5 can not only ensure the effective volume of the gas-fired heating furnace, but also avoid the intermediate alloy feeder 5 being too close to the top of the gas-fired heating furnace, which may cause splashing on the surface of the pure aluminum melt when adding the intermediate alloy, thereby increasing the content of oxide slag in the melt.

[0051] According to an embodiment of the present invention, the gas heater 6 is used to heat the gas heating furnace to a certain temperature to achieve the preparation of aluminum alloy melt. The gas heater 6 is arranged on the side wall of the gas heating furnace and close to the top of the gas heating furnace; such a position setting can ensure that the gas heater 6 is located above the liquid surface of the aluminum alloy melt to achieve the preparation of the aluminum alloy melt in the gas heating furnace. The number of the gas heaters 6 is 2-6. The operating temperature of the gas heater 6 is 650℃-1250℃, the temperature control accuracy is less than ±6℃, the thermal efficiency is 84%-96%, and the gas flow rate is 65m 3 ·h -1 -125m 3 ·h -1 .

[0052] According to an embodiment of the present invention, the melt feed filter 7 is used to filter out solid impurities from the pure aluminum melt fed into the gas-fired heating furnace. The raw material used in the present invention is pure aluminum melt sourced from an electrolytic aluminum smelter. This operation directly filters out solid impurities from the pure aluminum melt before use, significantly improving the metallurgical quality of the melt. The melt feed filter 7 utilizes a double-layer ceramic filter screen: the upper layer is made of ZrO2 with a pore size of 250μm-450μm; the lower layer is made of Y2O3 with a pore size of 80μm-120μm.

[0053] According to an embodiment of the present invention, the gas heating furnace level gauge 8 is used to monitor the liquid level of the aluminum alloy melt in the gas heating furnace in real time. The gas heating furnace level gauge 8 can be a high temperature resistant level gauge known in the art.

[0054] According to an embodiment of the present invention, the automatic slag skimmer 9 is used to remove slag formed on the surface of the aluminum alloy melt after refining, degassing, and / or grain refinement. The automatic slag skimmer 9 is made of graphite and has a V-shaped cross-section. The distance between the two end points of the V is no less than 600 mm.

[0055] According to an embodiment of the present invention, the mechanical stirrer 10 is used to stir the aluminum alloy melt in the gas-fired heating furnace. The mechanical stirrer 10 is made of silicon carbide. The mechanical stirrer 10 is installed at the top of the gas-fired heating furnace and extends to 1 / 3 to 2 / 3 of the height of the aluminum alloy melt in the gas-fired heating furnace.

[0056] According to an embodiment of the present invention, the exhaust smoke and exhaust gas generated during the heating process of the gas-fired heating furnace are discharged through a furnace gas exhaust duct 11 arranged outside the low-pressure casting furnace. By locating the furnace gas exhaust duct 11 outside the furnace lining 23 of the low-pressure casting furnace, it can provide excellent thermal insulation for the low-pressure casting furnace, significantly reducing the energy consumption of the low-pressure casting furnace and significantly reducing production costs.

[0057] According to an embodiment of the present invention, the material of the double furnace stop plug 12 is aluminum silicate ceramic fiber, wherein the mass percentage of Al2O3 is ≥60%, the mass percentage of SiO2 is ≥30%, and the mass percentage of Fe2O3 is <0.12%.

[0058] According to an embodiment of the present invention, the automatic angle gauge 13 has an oscillation angle range of 0°-60°. The automatic angle gauge 13 is mechanically connected to the dual-furnace blocking plug 12. The oscillation of the automatic angle gauge 13 drives the dual-furnace blocking plug 12 in a circular motion, thereby opening the passage between the gas-fired heating furnace and the low-pressure casting furnace, enabling dynamic replenishment of the aluminum alloy melt in the low-pressure casting furnace.

[0059] According to an embodiment of the present invention, the low-pressure casting furnace heater 14 is used to maintain the temperature of the aluminum alloy melt in the low-pressure casting furnace within a certain temperature range (e.g., 710°C-730°C). The low-pressure casting furnace heater 14 is made of silicon carbon rods. The number of the low-pressure casting furnace heaters 14 is 5-8. The low-pressure casting furnace heaters 14 are arranged on the side wall of the low-pressure casting furnace and close to the bottom of the low-pressure casting furnace; such a positioning ensures that the low-pressure casting furnace heaters 14 are located below the liquid surface of the aluminum alloy melt, thereby maintaining the temperature of the aluminum alloy melt in the low-pressure casting furnace within a certain range. The heating power of the low-pressure casting furnace heater 14 is 2.5kW-4.0kW.

[0060] According to an embodiment of the present invention, high-pressure air is introduced into the low-pressure casting furnace through the pressure pipe 15. The high-pressure air enters the low-pressure casting furnace and applies a certain pressure to the surface of the aluminum alloy melt. Under the action of pressure, the aluminum alloy melt completes low-pressure filling and pressurized solidification along the riser pipe 16. By controlling the pressure of the high-pressure gas introduced into the pressure pipe 15, the filling speed, filling pressure, liquid rise speed, liquid rise pressure and pressurization pressure during the low-pressure casting process can be regulated. The high-pressure gas introduced into the pressure pipe 15 is dry compressed air with a humidity of ≤30% RH. The pressure of the gas introduced during the filling stage is 0.10MPa-0.15MPa, and the pressure of the gas introduced during the pressure holding stage is 0.15MPa-0.25MPa.

[0061] According to an embodiment of the present invention, the riser tube 16 is made of stainless steel coated with a high-temperature resistant coating. The high-temperature resistant coating comprises CaCO3, ZnO, Na2O·nSiO2, and H2O, wherein the mass of CaCO3 accounts for 8.5%-9.5% of the total mass of the high-temperature resistant coating, the mass of ZnO accounts for 5.0%-6.0% of the total mass of the high-temperature resistant coating, the mass of Na2O·nSiO2 accounts for 5.2%-6.4% of the total mass of the high-temperature resistant coating, and the balance is H2O.

[0062] According to an embodiment of the present invention, the liquid melt density meter 17 is used to measure the density of the aluminum alloy melt in the low-pressure casting furnace, and then quickly detect the chemical composition of the aluminum alloy melt in the low-pressure casting furnace. Since heavy metals such as Zr, V, and Cd in the alloy components are prone to precipitation, it is easy to cause the composition of the aluminum alloy melt near the riser inlet to change. By setting the liquid melt density meter 17, the chemical composition of the aluminum alloy melt in the low-pressure casting furnace can be quickly detected. By starting the liquid melt density meter 17 and detecting the density of the aluminum alloy melt in the low-pressure casting furnace under different temperature conditions, and coupling and comparing it with the density of the prepared target alloy composition melt, the chemical composition of the aluminum alloy melt in the low-pressure casting furnace can be quickly detected. The measurement range of the liquid melt density meter 17 is 2.0 g·cm -3 -3.0g·cm -3 , resolution <0.005g·cm -3 The measurement principle is vibration tube type, the response time is ≤5s, a honeycomb ceramic filter is installed at the inlet of the vibration tube, the pore size of the honeycomb ceramic filter is ≤0.5mm, and the sensor surface is coated with titanium nitride coating.

[0063] According to an embodiment of the present invention, the low-pressure casting furnace level gauge 18 is used to monitor the liquid level of the aluminum alloy melt in the low-pressure casting furnace in real time. The low-pressure casting furnace level gauge 18 can be a high-temperature resistant level gauge known in the art.

[0064] According to the embodiment of the present invention, the furnace gas exhaust brake ball valve 19 can, on the one hand, purify the waste smoke and exhaust gas in the furnace gas exhaust pipe 11 to reduce pollution to the environment; on the other hand, it can control the opening and closing of the furnace gas exhaust pipe 11, thereby controlling the gas pressure in the furnace gas exhaust pipe 11. By regulating the gas pressure in the furnace gas exhaust pipe 11, it can also play an optimal role in thermal insulation, fully utilize the energy of the waste smoke and exhaust gas in the furnace gas exhaust pipe 11, reduce the energy consumption of the low-pressure casting furnace heater 14, and significantly reduce production costs. The sealing form of the furnace gas exhaust brake ball valve 19 is PTFE soft seal, and the driving mode is pneumatic. The reaction time of opening and closing of the furnace gas exhaust brake ball valve 19 is ≤0.5s, and the sealing level is ≤1.2×10 -6 mbar·L·s -1 .

[0065] According to an embodiment of the present invention, an inert gas is introduced into the low-pressure casting furnace through the inert gas inlet 20 to achieve temperature adjustment and static placement of the aluminum alloy melt under the protection of the inert gas, thereby preventing the surface aluminum alloy melt from forming Al2O3 and AlN oxide inclusions with O2 and N2, thereby reducing the metallurgical quality. The inert gas introduced into the inert gas inlet 20 is a mixed gas, wherein the volume of He gas accounts for 60%-68% of the total volume of the mixed gas, the volume of Ar gas accounts for 26%-30% of the total volume of the mixed gas, and the volume of CO2 accounts for 2%-14% of the total volume of the mixed gas; the inert gas introduction flow rate is 1.5L·s -1 -4.0L·s -1 The study found that when the inert gas is a mixture of argon, helium and CO2, on the one hand, because the density of argon and CO2 is higher than that of air; therefore, the argon and CO2 introduced during the low-pressure casting process will adhere to the surface of the aluminum alloy melt, which is equivalent to forming a layer of inert gas as a protective layer on the surface of the aluminum alloy melt, isolating it from the compressed air introduced subsequently, thereby effectively preventing the surface aluminum alloy melt from forming Al2O3 and AlN oxide inclusions with O2 and N2 in the compressed air; on the other hand, the addition of a small amount of CO2 will react with the aluminum liquid to generate γ-Al2O3 and CO. The CO generated by the reaction It can reduce the tension gradient on the surface of the aluminum alloy melt, promote the uniform spreading of the liquid film on the surface of the aluminum alloy melt, and reduce the tendency of air entrainment during low-pressure casting. On the other hand, the introduction of CO2 will promote the formation of a dense structure of α-Al2O3 (film thickness ≤ 30nm) on the surface of the aluminum alloy melt (only under the protection of argon and helium, the thin film generated on the surface of the aluminum alloy melt is often a porous structure of γ-Al2O3 (film thickness 50-100nm), which is easy to break). The oxygen barrier efficiency is improved by 40%, and the hardness of the α-Al2O3 film can reach 1800HV, and the cracks in the film layer on the melt surface can be reduced by about 70%.

[0066] According to the embodiment of the present invention, the temperature of the aluminum alloy melt in the low-pressure casting furnace is monitored in real time by using a thermocouple 21 at the side of the low-pressure casting furnace and a thermocouple 22 at the bottom of the low-pressure casting furnace. The thermocouple 21 at the side of the low-pressure casting furnace and the thermocouple 22 at the bottom of the low-pressure casting furnace are type B thermocouples, and the thermal response time T 0.5 The temperature is 35s-60s, the tolerance level is ≤2℃, and the material of the protective tube is Al2O3.

[0067] According to an embodiment of the present invention, the material of the furnace lining 23 of the low-pressure casting furnace is a gradient composite structure material, including a five-layer structure, wherein the material of the first layer structure in contact with the melt is alumina insulation brick with a thickness of 100mm-120mm; the material of the second layer structure in contact with the first layer structure is silica nano-microporous insulation board with a thickness of 1.5mm-2.5mm; the material of the third layer structure in contact with the second layer structure is polycrystalline mullite fiber PMF with a thickness of 3.5mm-6.0mm; the material of the fourth layer structure in contact with the third layer structure is diatomaceous earth with a thickness of 45mm-60mm; the material of the fifth layer structure in contact with the fourth layer structure is zircon hollow brick with a thickness of 60mm-100mm and a porosity of 45%-60%.

[0068] According to an embodiment of the present invention, the material of the furnace lining 24 of the gas heating furnace is a gradient composite structure material, including a five-layer structure, wherein the material of the first layer structure in contact with the melt is alumina insulation brick with a thickness of 100mm-120mm; the material of the second layer structure in contact with the first layer structure is silica nano-microporous insulation board with a thickness of 1.5mm-2.5mm; the material of the third layer structure in contact with the second layer structure is polycrystalline mullite fiber PMF with a thickness of 3.5mm-6.0mm; the material of the fourth layer structure in contact with the third layer structure is diatomaceous earth with a thickness of 45mm-60mm; the material of the fifth layer structure in contact with the fourth layer structure is zircon hollow brick with a thickness of 60mm-100mm and a porosity of 45%-60%.

[0069] According to an embodiment of the present invention, the melt extraction and pressure pump 25 is arranged inside the gas heating furnace and close to one side of the double furnace stop plug 12; the melt extraction and pressure pump 25 is used to pump the aluminum alloy melt in the gas heating furnace through the double furnace stop plug 12 into the low-pressure casting furnace, thereby realizing dynamic replenishment of the aluminum alloy melt in the low-pressure casting furnace.

[0070] According to the implementation scheme of the present invention, the content of the aluminum alloy melt in the gas heating furnace and the low-pressure casting furnace is detected before low-pressure casting. When the gas heating furnace level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas heating furnace is higher than the first threshold, and the low-pressure casting furnace level gauge 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is higher than the second threshold, it means that the content of the aluminum alloy melt in the gas heating furnace and the low-pressure casting furnace is sufficient, and low-pressure casting can be performed without replenishing the aluminum alloy melt in the low-pressure casting furnace. At this time, the gas heating furnace and the low-pressure casting furnace should be in a non-connected state, that is, the automatic swing angle meter 13 is adjusted to make the double-furnace stop plug 12 in a closed state, and at the same time, the melt extraction pressure pump 25 is turned off; the pressure pipe 15 is opened to introduce high-pressure gas into the low-pressure casting furnace; the liquid riser 16 is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to realize the casting and forming of aluminum alloy metal products.

[0071] According to the implementation scheme of the present invention, the content of the aluminum alloy melt in the gas-fired heating furnace and the low-pressure casting furnace is detected before low-pressure casting. When the gas-fired heating furnace level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is higher than the first threshold value, and the low-pressure casting furnace level gauge 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is lower than the second threshold value, it means that the content of the aluminum alloy melt in the gas-fired heating furnace is sufficient, but the content of the aluminum alloy melt in the low-pressure casting furnace is insufficient. The aluminum alloy melt in the low-pressure casting furnace needs to be replenished before low-pressure casting can be carried out. At this time, the gas-fired heating furnace and the low-pressure casting furnace should be in a connected state, that is, the automatic swing angle meter 13 is adjusted to make the double-furnace anti-passage plug 12 in an open state (it can also be understood as adjusting the automatic swing angle meter 13 to drive the double-furnace anti-passage plug 12 performs circular swing), and at the same time, the melt extraction and pressure pump 25 is turned on to realize the double-action serial circulation of the aluminum alloy melt; further, when the low-pressure casting furnace level gauge 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is higher than the third threshold value, it means that the aluminum alloy melt content in the low-pressure casting furnace is sufficient, and low-pressure casting can be carried out without replenishing the aluminum alloy melt in the low-pressure casting furnace. At this time, the gas heating furnace and the low-pressure casting furnace should be in a non-connected state, that is, the automatic swing angle meter 13 is adjusted to make the double-furnace anti-pass plug 12 in a closed state, and at the same time, the melt extraction and pressure pump 25 is turned off; the pressure pipe 15 is opened to introduce high-pressure gas into the low-pressure casting furnace; the liquid riser 16 is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to realize the casting and forming of aluminum alloy metal products.

[0072] According to the embodiment of the present invention, the content of the aluminum alloy melt in the gas heating furnace and the low-pressure casting furnace is detected before low-pressure casting. When the gas heating furnace liquid level meter 8 detects that the liquid level of the aluminum alloy melt in the gas heating furnace is lower than the first threshold, it means that the content of the aluminum alloy melt in the gas heating furnace is insufficient and the quality is poor, and the aluminum alloy melt in the low-pressure casting furnace cannot be replenished. It is necessary to continue to add pure aluminum melt and intermediate alloy to the gas heating furnace for melt preparation. At this time, the gas heating furnace and the low-pressure casting furnace should be in a non-connected state, that is, adjust The automatic oscillating angle meter 13 puts the double furnace anti-unblocking plug 12 into a closed state, and at the same time turns off the melt extraction and pressure pump 25; after the preparation of the aluminum alloy melt is completed, the gas heating furnace liquid level meter 8 detects that the liquid level of the aluminum alloy melt in the gas heating furnace is higher than the first threshold value, and according to the liquid level of the aluminum alloy melt in the low-pressure casting furnace detected by the low-pressure casting furnace liquid level meter 18 (the low-pressure casting furnace liquid level meter 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is lower than the second threshold value or higher than the second threshold value), the low-pressure casting is completed according to the above steps.

[0073] According to the implementation scheme of the present invention, research has found that if before low-pressure casting, the gas heating furnace level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas heating furnace is lower than the first threshold value, and the double furnace stop plug 12 is still in the open state, it will cause the oxidation slag and other defects generated in the smelting process of the aluminum alloy in the gas heating furnace to enter the low-pressure casting furnace, contaminating the aluminum alloy melt in the furnace, causing a large number of defects in the low-pressure cast products, low batch production qualification rate, coarse cast grain structure, poor metallurgical quality and low mechanical properties.

[0074] According to the embodiment of the present invention, the effective total height of the gas heating furnace body refers to the distance between the bottom of the intermediate alloy feeder 5 and the bottom of the gas heating furnace; the effective total height of the low-pressure casting furnace body refers to the distance between the bottom of the inert gas inlet 20 and the bottom of the low-pressure casting furnace.

[0075] According to the implementation scheme of the present invention, the high-quality melt provided by the gas heating furnace can be continuously and uninterruptedly dynamically replenished to the low-pressure casting furnace, which greatly improves the working efficiency of low-pressure casting. Moreover, the dynamic replenishment has little fluctuation on the surface of the aluminum alloy melt in the low-pressure casting furnace, and will not produce obvious turbulence, air entanglement, and slag inclusion. At the same time, the replenished aluminum alloy melt is of high quality and has a low content of oxidized slag inclusions, which greatly improves the metallurgical quality of the melt, significantly improves production efficiency, reduces manufacturing costs, and improves the batch production qualification rate, and solves process problems such as coarse cast grain structure, poor metallurgical quality, and low mechanical properties.

[0076] The present invention also provides a method for preparing a double-action serial circulation high-purity aluminum melt. The method is implemented based on the above-mentioned double-action serial circulation high-purity aluminum melt low-pressure casting device, and the method comprises the following steps:

[0077] 1) Charging and melting: Pure aluminum melt is added to the gas-fired heating furnace through the melt feeding filter 7. Master alloy is prepared according to the alloy composition and added to the gas-fired heating furnace through the master alloy feeder 5. The gas heater 6 is turned on and the temperature in the gas-fired heating furnace is adjusted until the master alloy is completely melted.

[0078] 2) Temperature adjustment and static placement: Start the low-pressure casting furnace heater 14 to adjust the temperature in the low-pressure casting furnace to a certain temperature range and keep it warm for a certain period of time; start the inert gas inlet 20 to introduce inert gas into the low-pressure casting furnace to provide inert atmosphere protection for the aluminum alloy melt;

[0079] 3) Melt double-action serial circulation and low-pressure casting: Before low-pressure casting, detect the content of aluminum alloy melt in the gas heating furnace and low-pressure casting furnace:

[0080] 3-1) When the gas-fired heating furnace level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is higher than a first threshold, and the low-pressure casting furnace level gauge 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is higher than a second threshold, the automatic oscillating angle meter 13 is adjusted to close the dual-furnace stop plug 12, and the melt extraction pressure pump 25 is simultaneously turned off; the pressure pipe 15 is opened to introduce high-pressure gas into the low-pressure casting furnace; the riser pipe 16 is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to achieve casting and forming of aluminum alloy metal products;

[0081] 3-2) When the gas heating furnace level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas heating furnace is higher than the first threshold value, and the low-pressure casting furnace level gauge 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is lower than the second threshold value, the automatic oscillating angle meter 13 is adjusted to open the double-furnace anti-flow plug 12, and the melt extraction and pressure pump 25 is turned on at the same time, so as to realize the double-action serial circulation of the aluminum alloy melt; when the low-pressure casting furnace level gauge 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is higher than the third threshold value, the automatic oscillating angle meter 13 is adjusted to close the double-furnace anti-flow plug 12, and the melt extraction and pressure pump 25 is turned off at the same time; the pressure pipe 15 is opened to introduce high-pressure gas into the low-pressure casting furnace; the liquid riser 16 is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to realize the casting and forming of aluminum alloy metal products;

[0082] 3-3) When the gas-fired heating furnace liquid level meter 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is lower than the first threshold value, pure aluminum melt and intermediate alloy are continued to be added to the gas-fired heating furnace to prepare the melt, the automatic swing angle meter 13 is adjusted to make the double furnace stop plug 12 in the closed state, and the melt extraction pressure pump 25 is turned off at the same time; after the aluminum alloy melt preparation is completed, and the gas-fired heating furnace liquid level meter 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is higher than the first threshold value, repeat step 3-1) or step 3-2) to achieve the casting of the aluminum alloy metal product.

[0083] According to an embodiment of the present invention, in the steps of double-action serial circulation of the melt and low-pressure casting, the first threshold value is 1 / 5 of the effective total height of the gas heating furnace body; the second threshold value is 1 / 4 of the effective total height of the low-pressure casting furnace body; and the third threshold value is the effective total height of the low-pressure casting furnace body.

[0084] According to an embodiment of the present invention, in the step of adding materials and melting, after the gas-fired heating furnace completes alloy smelting, a small amount of alloy melt is scooped out to cast a chemical composition test block, and the chemical composition of the melt in the gas-fired heating furnace is tested by ICP or other chemical testing methods. If the requirements are not met, an intermediate alloy of corresponding composition is prepared according to the chemical composition test results for additional smelting, and the chemical composition of the melt in the gas-fired heating furnace is retested until it is qualified.

[0085] According to an embodiment of the present invention, in the step of temperature adjustment and standing, the temperature range of the aluminum alloy melt in the low-pressure casting furnace during the temperature adjustment and standing process is 710°C-730°C, and the insulation time is 16min-24min. In the step of temperature adjustment and standing, the temperature of the aluminum alloy melt in the low-pressure casting furnace is monitored in real time by a thermocouple 21 at the side end of the low-pressure casting furnace and a thermocouple 22 at the bottom end of the low-pressure casting furnace. In the step of temperature adjustment and standing, the inert gas introduced can continuously provide an inert atmosphere protection for the aluminum alloy melt in the low-pressure casting furnace, thereby preventing the aluminum alloy melt on the surface from forming Al2O3 and AlN oxide inclusions with O2 and N2.

[0086] According to an embodiment of the present invention, the temperature adjustment and standing step is set to provide an incubation period for grain refinement, so that the grain refining powder added to the gas heating furnace can fully play its role and ensure that the Al3Ti, AlB2, Al3Zr, Al3Sc and TiB2 nucleation particles formed in the aluminum alloy melt are more evenly distributed, which is beneficial to improving the metallurgical quality of the aluminum alloy melt.

[0087] According to an embodiment of the present invention, in the steps of double-action serial circulation of the melt and low-pressure casting, the liquid melt density meter 17 is started and the density of the aluminum alloy melt in the low-pressure casting furnace under different temperature conditions is detected, and coupled comparison is performed with the density of the prepared target alloy composition melt, thereby achieving the purpose of quickly detecting the composition of the aluminum alloy melt in the low-pressure casting furnace.

[0088] According to an embodiment of the present invention, the following steps are further included before the melt double-action serial circulation and low-pressure casting steps:

[0089] 1') Refining and degassing: Turn on the argon generator 1, open the powder refining agent inlet 3 and press the powder refining agent into the gas-fired heating furnace to refine and degas the aluminum alloy melt in the gas-fired heating furnace. During the refining and degassing process, start the mechanical stirrer 10 to mechanically stir the aluminum alloy melt. After refining and degassing, use the automatic slag skimmer 9 to skim off the slag formed on the surface of the aluminum alloy melt after the refining and degassing reaction.

[0090] 1'') Grain refinement: Turn on the ultrasonic vibrator 2, open the grain refinement powder inlet 4 and press the grain refinement powder into the gas-fired heating furnace to perform grain refinement on the aluminum alloy melt in the gas-fired heating furnace. During the grain refinement treatment, start the mechanical stirrer 10 to mechanically stir the aluminum alloy melt. After the grain refinement, use the automatic slag skimmer 9 to skim off the slag formed on the surface of the aluminum alloy melt after the grain refinement reaction.

[0091] According to an embodiment of the present invention, during the refining and degassing step, the temperature of the aluminum alloy melt in the gas-fired heating furnace is 720°C-750°C. During the refining and degassing step, the stirring speed of the mechanical stirrer 10 is 450 r·min. -1 -800r·min -1 , stirring time is 14min-20min.

[0092] According to an embodiment of the present invention, in the step of grain refinement, the temperature of the aluminum alloy melt in the gas-fired heating furnace is 740°C-780°C. In the step of grain refinement, the stirring speed of the mechanical stirrer 10 is 550 r·min. -1 -850r·min -1 , stirring time is 10min-15min.

[0093] According to an embodiment of the present invention, the method further comprises the steps of:

[0094] 5) Smoke and dust purification and removal: By controlling the opening and closing of the furnace gas exhaust brake ball valve 19, the waste smoke and exhaust gas discharged from the gas heating furnace are purified and the pressure of the waste smoke and exhaust gas in the furnace gas exhaust pipe 11 is controlled at the same time.

[0095] According to the embodiment of the present invention, by regulating the pressure of the waste smoke and exhaust gas in the furnace gas exhaust duct 11, when the pressure of the waste smoke and exhaust gas reaches 120kPa-135kPa, it can play an optimal thermal insulation role, play a better overall thermal insulation role for the low-pressure casting furnace, reduce the energy consumption of the low-pressure casting furnace heater 14, and reduce production costs.

[0096] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0097] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the reagents, materials, etc. used in the following examples are all commercially available unless otherwise specified.

[0098] Example 1

[0099] This embodiment provides a double-action serial circulation high-purity aluminum melt low-pressure casting device, wherein the low-pressure casting device includes a gas heating furnace and a low-pressure casting furnace; the gas heating furnace is arranged on one side of the low-pressure casting furnace, and the gas heating furnace and the low-pressure casting furnace are connected through a double furnace stop plug 12; the gas heating furnace also includes a gas heating furnace lining 24; the low-pressure casting furnace also includes a low-pressure casting furnace lining 23;

[0100] The gas-fired heating furnace includes an intermediate alloy feeder 5, a gas heater 6, a melt feeding filter 7, a gas-fired heating furnace level gauge 8, and a melt extraction and pressure pump 25; the intermediate alloy feeder 5 and the gas heater 6 are arranged on the side wall of the gas-fired heating furnace; the melt feeding filter 7 is arranged on the top of the gas-fired heating furnace; the gas-fired heating furnace level gauge 8 is arranged on the top of the gas-fired heating furnace and extends into the interior of the gas-fired heating furnace; the melt extraction and pressure pump 25 is arranged inside the gas-fired heating furnace;

[0101] The low-pressure casting furnace includes an automatic oscillating angle meter 13, a low-pressure casting furnace heater 14, a pressurizing pipe 15, a liquid riser 16, a low-pressure casting furnace liquid level meter 18, and an inert gas inlet 20; the low-pressure casting furnace heater 14 and the inert gas inlet 20 are arranged on the side wall of the low-pressure casting furnace; the pressurizing pipe 15 is arranged on the top of the low-pressure casting furnace; the automatic oscillating angle meter 13, the liquid riser 16, and the low-pressure casting furnace liquid level meter 18 are arranged on the top of the low-pressure casting furnace and extend into the interior of the low-pressure casting furnace; the automatic oscillating angle meter 13 is connected to the double furnace stop plug 12;

[0102] The gas-fired heating furnace also includes an argon generator 1, an ultrasonic vibrator 2, a powder refining agent inlet 3 and a grain refining powder inlet 4; the argon generator 1 and the ultrasonic vibrator 2 are arranged at the bottom of the gas-fired heating furnace; the powder refining agent inlet 3 and the grain refining powder inlet 4 are arranged on the side wall of the gas-fired heating furnace; the gas-fired heating furnace also includes an automatic slag scoop 9 and a mechanical stirrer 10; the automatic slag scoop 9 and the mechanical stirrer 10 are arranged at the top of the gas-fired heating furnace and extend to the interior of the gas-fired heating furnace; the gas-fired heating furnace also includes a furnace gas exhaust pipe 11; the inlet of the furnace gas exhaust pipe 11 is arranged at the top of the gas-fired heating furnace, and the furnace gas exhaust pipe 11 is arranged on the outside of the furnace lining 23 of the low-pressure casting furnace.

[0103] The low-pressure casting furnace includes a liquid melt density meter 17, a furnace gas exhaust brake ball valve 19, a low-pressure casting furnace side end thermocouple 21 and a low-pressure casting furnace bottom end thermocouple 22; the low-pressure casting furnace side end thermocouple 21 is arranged on the side wall of the low-pressure casting furnace; the liquid melt density meter 17 is arranged at the top of the low-pressure casting furnace and extends to the interior of the low-pressure casting furnace; the low-pressure casting furnace bottom end thermocouple 22 is arranged at the bottom of the low-pressure casting furnace; the furnace gas exhaust brake ball valve 19 is arranged at the outlet of the furnace gas exhaust pipe 11.

[0104] Example 2

[0105] This embodiment provides a method for preparing a double-action serial circulation high-purity aluminum melt. The method is based on the double-action serial circulation high-purity aluminum melt low-pressure casting device described in Example 1. The method comprises the following steps:

[0106] a) Charging and Melting: Pure aluminum melt is added to the gas-fired heating furnace through the melt feeding filter 7. A master alloy is prepared according to the alloy composition and added to the gas-fired heating furnace through the master alloy feeder 5. The gas heater 6 is turned on and the temperature in the gas-fired heating furnace is adjusted until the master alloy is completely melted.

[0107] b) Refining and degassing: The argon generator 1 is turned on, the powder refining agent inlet 3 is opened and the powder refining agent is pressed into the gas-fired heating furnace to refine and degas the aluminum alloy melt in the gas-fired heating furnace. During the refining and degassing process, the mechanical stirrer 10 is started to mechanically stir the aluminum alloy melt. After refining and degassing, the slag formed on the surface of the aluminum alloy melt after the refining and degassing reaction is skimmed off using an automatic slag skimmer 9. During the refining and degassing step, the temperature of the aluminum alloy melt in the gas-fired heating furnace is 735°C. The stirring speed of the mechanical stirrer 10 is 650 rpm. -1 , stirring time is 17min;

[0108] c) Grain refinement: The ultrasonic vibrator 2 is turned on, the grain refinement powder feeder 4 is opened, and the grain refinement powder is pressed into the gas-fired heating furnace to perform grain refinement on the aluminum alloy melt in the gas-fired heating furnace. During the grain refinement process, the mechanical stirrer 10 is started to mechanically stir the aluminum alloy melt. After the grain refinement, the slag formed on the surface of the aluminum alloy melt after the grain refinement reaction is skimmed off using an automatic slag skimmer 9. During the grain refinement process, the temperature of the aluminum alloy melt in the gas-fired heating furnace is 760° C. The stirring speed of the mechanical stirrer 10 is 650 rpm. -1 , stirring time is 12min;

[0109] d) Temperature adjustment and static holding: starting the low-pressure casting furnace heater 14 to adjust the temperature in the low-pressure casting furnace to a certain temperature range and maintaining the temperature for a certain time; starting the inert gas inlet 20 to introduce inert gas into the low-pressure casting furnace to provide an inert atmosphere protection for the aluminum alloy melt; during the temperature adjustment and static holding step, the temperature range of the aluminum alloy melt in the low-pressure casting furnace is 720° C., and the holding time is 20 minutes;

[0110] e) Melt double-action serial circulation and low-pressure casting: Before low-pressure casting, detect the content of aluminum alloy melt in the gas heating furnace and low-pressure casting furnace:

[0111] e-1) When the gas-fired heating furnace level gauge 8 detects that the aluminum alloy melt in the gas-fired heating furnace is above a first threshold, and the low-pressure casting furnace level gauge 18 detects that the aluminum alloy melt in the low-pressure casting furnace is above a second threshold, the automatic oscillating angle gauge 13 is adjusted to close the dual-furnace stop plug 12, and the melt extraction and pressure pump 25 is simultaneously turned off; the pressure pipe 15 is opened to allow high-pressure gas to flow into the low-pressure casting furnace; the riser pipe 16 is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to form an aluminum alloy metal product;

[0112] e-2) When the gas-fired heating furnace level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is higher than a first threshold value, and the low-pressure casting furnace level gauge 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is lower than a second threshold value, the automatic oscillating angle gauge 13 is adjusted to open the double-furnace stopper plug 12, and the melt extraction and pressure pump 25 is simultaneously turned on to achieve double-action serial circulation of the aluminum alloy melt; when the low-pressure casting furnace level gauge 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is higher than a third threshold value, the automatic oscillating angle gauge 13 is adjusted to close the double-furnace stopper plug 12, and the melt extraction and pressure pump 25 is simultaneously turned off; the pressure pipe 15 is opened to introduce high-pressure gas into the low-pressure casting furnace; the liquid riser 16 is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to achieve casting and forming of aluminum alloy metal products;

[0113] e-3) When the gas-fired heating furnace liquid level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is lower than the first threshold, pure aluminum melt and master alloy are continued to be added to the gas-fired heating furnace to prepare the melt, the automatic oscillating angle gauge 13 is adjusted to close the double-furnace stop plug 12, and the melt extraction and pressure pump 25 is turned off. After the aluminum alloy melt is prepared, and the gas-fired heating furnace liquid level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is higher than the first threshold, step e-1) or step e-2) is repeated to achieve the casting of the aluminum alloy metal product.

[0114] In the steps of double-action serial circulation of the melt and low-pressure casting, the first threshold value is 1 / 5 of the effective total height of the gas heating furnace body; the second threshold value is 1 / 4 of the effective total height of the low-pressure casting furnace body; and the third threshold value is the effective total height of the low-pressure casting furnace body. In the steps of double-action serial circulation of the melt and low-pressure casting, the liquid melt densitometer 17 is started and the density of the aluminum alloy melt in the low-pressure casting furnace under different temperature conditions is detected, and the density is coupled and compared with the density of the prepared target alloy composition melt, thereby achieving the purpose of quickly detecting the composition of the aluminum alloy melt in the low-pressure casting furnace;

[0115] f) Smoke and dust purification and removal: By controlling the opening and closing of the furnace gas exhaust brake ball valve 19, the waste smoke and exhaust gas discharged from the gas heating furnace are purified and the pressure of the waste smoke and exhaust gas in the furnace gas exhaust pipe 11 is controlled at the same time.

[0116] In a preferred embodiment of the present invention, the number of the argon generators 1 is 5, and the distance between them is 500 mm. The flow rate of the argon gas introduced into the argon generator 1 is 3.5 L·min -1 . The number of the powder refining agent inlet devices 3 is 3, and the distance between them is 550 mm. The powder refining agent inlet devices 3 are arranged on the side wall of the gas heating furnace and close to the bottom of the gas heating furnace. The powder refining agent is composed of Na3AlF6, KCl, CaCl2, TiO2, C2Cl6 and Na2SiF6, Na3AlF6 accounts for 6% of the total weight of the powder refining agent, KCl accounts for 3% of the total weight of the powder refining agent, TiO2 accounts for 22% of the total weight of the powder refining agent, C2Cl6 accounts for 51% of the total weight of the powder refining agent, Na2SiF6 accounts for 5% of the total weight of the powder refining agent, and the balance is CaCl2.

[0117] In a preferred embodiment of the present invention, the number of the ultrasonic exciters 2 is 3, and the distance between them is 420 mm. The ultrasonic excitation frequency emitted by the ultrasonic exciter 2 is 24 kHz, the ultrasonic excitation amplitude is 50 μm, the ultrasonic excitation mode is a pulse mode, and the duty cycle is 75%. The number of the grain refining powder inlet devices 4 is 2, and the distance between them is 520 mm. The grain refining powder inlet devices 4 are arranged on the side wall of the gas-fired heating furnace and close to the bottom of the gas-fired heating furnace. The grain refining powder is composed of K2TiF6, KBF4, K2ZrF6 and Sc2O3, K2TiF6 accounts for 36.5% of the total weight of the grain refining powder, KBF4 accounts for 30% of the total weight of the grain refining powder, K2ZrF6 accounts for 19% of the total weight of the grain refining powder, and the balance is Sc2O3.

[0118] In a preferred embodiment of the present invention, the number of the intermediate alloy feeder 5 is 1. The intermediate alloy ingot is added to the gas-fired heating furnace through the intermediate alloy feeder 5; the intermediate alloy needs to be heat-baked before being added to the gas-fired heating furnace. The heat baking temperature is 250°C and the heat baking time is 30 minutes. The purpose of heat baking is to remove oil and moisture on the surface of the intermediate alloy and improve the quality of the aluminum alloy melt. The intermediate alloy feeder 5 is arranged on the side wall of the gas-fired heating furnace, and the distance between it and the top of the gas-fired heating furnace is 350mm. The gas heater 6 is located on both sides of the upper end of the gas-fired heating furnace, the number is 4, the working temperature is 900°C, the temperature control accuracy is ±4°C, the thermal efficiency is 90%, and the gas flow rate is 95m 3 ·h -1 The melt feeding filter 7 adopts a double-layer ceramic filter screen, wherein the upper ceramic filter screen is made of ZrO2 with a pore size of 350 μm; the lower ceramic filter screen is made of Y2O3 with a pore size of 100 μm.

[0119] In a preferred embodiment of the present invention, the automatic skimmer 9 is made of graphite and has a V-shaped cross-section, with the distance between the two endpoints of the V being 640 mm. The mechanical stirrer 10 is made of silicon carbide and is installed at the top of the gas-fired furnace, extending to half the height of the aluminum alloy melt within the furnace.

[0120] In a preferred embodiment of the present invention, the material of the double furnace stop plug 12 is aluminum silicate ceramic fiber, wherein the Al2O3 content is 64.9%, the SiO2 content is 35%, and the Fe2O3 content is 0.1%. The swing angle range of the automatic oscillating angle meter 13 is 0°-60°. The automatic oscillating angle meter 13 is connected to the double furnace stop plug 12 through a mechanical structure. After the automatic oscillating angle meter 13 swings, it will drive the double furnace stop plug 12 to perform a circular motion together, thereby opening the channel between the gas heating furnace and the low-pressure casting furnace, and realizing the dynamic replenishment of the aluminum alloy melt in the low-pressure casting furnace.

[0121] In a preferred embodiment of the present invention, the low-pressure casting furnace heater 14 is made of silicon carbon rods. There are six low-pressure casting furnace heaters 14 . Each heater 14 is located on the side wall of the low-pressure casting furnace, near the bottom of the furnace. The heating power of each heater 14 is 3.5 kW.

[0122] In a preferred embodiment of the present invention, the high-pressure gas introduced into the pressurized pipe 15 is dry compressed air with a humidity of 25% RH. The gas pressure in the filling stage is 0.12 MPa, and the gas pressure in the pressure-holding stage is 0.18 MPa. The riser pipe 16 is made of stainless steel and coated with a high-temperature resistant coating. The high-temperature resistant coating is composed of CaCO3, ZnO, Na2O·nSiO2 and H2O, wherein CaCO3 accounts for 9.0% of the total weight of the high-temperature resistant coating, ZnO accounts for 5.5% of the total weight of the high-temperature resistant coating, Na2O·nSiO2 accounts for 5.8% of the total weight of the high-temperature resistant coating, and the remainder is H2O. The measuring range of the liquid melt density meter 17 is 2.0 g·cm -3 -3.0g·cm -3 , with a resolution of 0.002 g·cm -3 The measurement principle is vibration tube type, the response time is 4s, a honeycomb ceramic filter is installed at the inlet of the vibration tube, the pore size of the honeycomb ceramic filter is 0.3mm, and the surface of the sensor is coated with titanium nitride coating.

[0123] In a preferred embodiment of the present invention, the sealing form of the furnace gas exhaust brake ball valve 19 is PTFE soft seal, the driving mode is pneumatic, the opening and closing reaction time of the furnace gas exhaust brake ball valve 19 is 0.3s, and the sealing grade is 0.8×10 -6 mbar·L·s -1 The inert gas introduced by the inert gas inlet 20 is a mixed gas, wherein He gas accounts for 66% by volume, Ar gas accounts for 28% by volume, and the remaining gas is CO2. The inert gas flow rate is 2.5 L·s -1The thermocouple 21 at the side of the low-pressure casting furnace and the thermocouple 22 at the bottom of the low-pressure casting furnace are made of B-type thermocouples, and the thermal response time T 0.5 The temperature is 45s, the tolerance level is 1°C, and the material of the protective tube is Al2O3.

[0124] In a preferred embodiment of the present invention, the material of the furnace lining 23 of the low-pressure casting furnace is a gradient composite structure material, including a five-layer structure, wherein the material of the first layer structure in contact with the melt is alumina insulation brick with a thickness of 110 mm; the material of the second layer structure in contact with the first layer structure is a silica nano-microporous insulation board with a thickness of 2.0 mm; the material of the third layer structure in contact with the second layer structure is polycrystalline mullite fiber PMF with a thickness of 4.5 mm; the material of the fourth layer structure in contact with the third layer structure is diatomaceous earth with a thickness of 55 mm; the material of the fifth layer structure in contact with the fourth layer structure is zircon hollow brick with a thickness of 80 mm and a porosity of 52%. The material of the furnace lining 24 of the gas heating furnace is a gradient composite structure material, including a five-layer structure, wherein the material of the first layer structure in contact with the melt is alumina insulation brick with a thickness of 110 mm; the material of the second layer structure in contact with the first layer structure is silica nano-microporous insulation board with a thickness of 2.0 mm; the material of the third layer structure in contact with the second layer structure is polycrystalline mullite fiber PMF with a thickness of 4.5 mm; the material of the fourth layer structure in contact with the third layer structure is diatomaceous earth with a thickness of 55 mm; the material of the fifth layer structure in contact with the fourth layer structure is zircon hollow brick with a thickness of 80 mm and a porosity of 52%.

[0125] The aluminum alloy metal product in Example 2 is an aluminum alloy wheel hub, and the material is A356.

[0126] Figure 6 The results of the solid hydrogen content comparison test of multiple furnace batches of a single-furnace low-pressure casting device, a publicly reported dual-furnace low-pressure casting device, and the dual-action serial circulation high-purity aluminum melt low-pressure casting device shown in Example 2 are shown. The test results show that when the single-furnace low-pressure casting device is used to batch produce aluminum alloy metal products, the solid hydrogen content ranges from 0.18-0.25ml / 100g. -1 Al, average value is 0.218ml·100g -1 Al; When aluminum alloy metal products are mass-produced in a double-furnace low-pressure casting device, the solid hydrogen content ranges from 0.12 to 0.16 ml / 100 g. -1 Al, average value is 0.139ml·100g -1 Al; When the dual-furnace low-pressure casting device of the present invention is used to batch produce aluminum alloy metal products, the solid hydrogen content range is 0.07-0.10ml·100g - 1 Al, average value is 0.085ml·100g-1 Al; It can be seen that compared with the single-furnace low-pressure casting device, the double-furnace low-pressure casting device of the present invention has an average decrease of 61% in solid hydrogen content, and compared with the publicly reported double-furnace low-pressure casting device, the double-furnace low-pressure casting device of the present invention has an average decrease of 39% in solid hydrogen content, indicating that the double-furnace low-pressure casting device of the present invention can obtain high-purity aluminum alloy melt.

[0127] Example 3

[0128] This embodiment provides a method for preparing a double-action serial circulation high-purity aluminum melt. The method is based on the double-action serial circulation high-purity aluminum melt low-pressure casting device described in Example 1. The method comprises the following steps:

[0129] a) Charging and Melting: Pure aluminum melt is added to the gas-fired heating furnace through the melt feeding filter 7. A master alloy is prepared according to the alloy composition and added to the gas-fired heating furnace through the master alloy feeder 5. The gas heater 6 is turned on and the temperature in the gas-fired heating furnace is adjusted until the master alloy is completely melted.

[0130] b) Refining and degassing: The argon generator 1 is turned on, the powder refining agent inlet 3 is opened and the powder refining agent is pressed into the gas-fired heating furnace to refine and degas the aluminum alloy melt in the gas-fired heating furnace. During the refining and degassing process, the mechanical stirrer 10 is started to mechanically stir the aluminum alloy melt. After the refining and degassing process, the slag formed on the surface of the aluminum alloy melt after the refining and degassing reaction is skimmed off using an automatic slag skimmer 9. During the refining and degassing process, the temperature of the aluminum alloy melt in the gas-fired heating furnace is 720°C. The stirring speed of the mechanical stirrer 10 is 450 rpm. -1 , stirring time is 14min;

[0131] c) Grain refinement: The ultrasonic vibrator 2 is turned on, the grain refinement powder feeder 4 is opened, and the grain refinement powder is pressed into the gas-fired heating furnace to perform grain refinement on the aluminum alloy melt in the gas-fired heating furnace. During the grain refinement process, the mechanical stirrer 10 is started to mechanically stir the aluminum alloy melt. After the grain refinement, the slag formed on the surface of the aluminum alloy melt after the grain refinement reaction is skimmed off using an automatic slag skimmer 9. During the grain refinement process, the temperature of the aluminum alloy melt in the gas-fired heating furnace is 740° C., and the stirring speed of the mechanical stirrer 10 is 550 rpm. -1 , stirring time is 15min;

[0132] d) Temperature adjustment and static holding: The low-pressure casting furnace heater 14 is started to adjust the temperature in the low-pressure casting furnace to a certain temperature range and maintain the temperature for a certain time; the inert gas inlet 20 is opened to introduce inert gas into the low-pressure casting furnace to provide an inert atmosphere protection for the aluminum alloy melt; during the temperature adjustment and static holding process, the temperature range of the aluminum alloy melt in the low-pressure casting furnace is 710° C., and the holding time is 16 minutes;

[0133] e) Melt double-action serial circulation and low-pressure casting: Before low-pressure casting, detect the content of aluminum alloy melt in the gas heating furnace and low-pressure casting furnace:

[0134] e-1) When the gas-fired heating furnace level gauge 8 detects that the aluminum alloy melt in the gas-fired heating furnace is above a first threshold, and the low-pressure casting furnace level gauge 18 detects that the aluminum alloy melt in the low-pressure casting furnace is above a second threshold, the automatic oscillating angle gauge 13 is adjusted to close the dual-furnace stop plug 12, and the melt extraction and pressure pump 25 is simultaneously turned off; the pressure pipe 15 is opened to allow high-pressure gas to flow into the low-pressure casting furnace; the riser pipe 16 is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to form an aluminum alloy metal product;

[0135] e-2) When the gas-fired heating furnace level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is higher than a first threshold value, and the low-pressure casting furnace level gauge 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is lower than a second threshold value, the automatic oscillating angle gauge 13 is adjusted to open the double-furnace stopper plug 12, and the melt extraction and pressure pump 25 is simultaneously turned on to achieve double-action serial circulation of the aluminum alloy melt; when the low-pressure casting furnace level gauge 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is higher than a third threshold value, the automatic oscillating angle gauge 13 is adjusted to close the double-furnace stopper plug 12, and the melt extraction and pressure pump 25 is simultaneously turned off; the pressure pipe 15 is opened to introduce high-pressure gas into the low-pressure casting furnace; the liquid riser 16 is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to achieve casting and forming of aluminum alloy metal products;

[0136] e-3) When the gas-fired heating furnace liquid level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is lower than the first threshold, pure aluminum melt and master alloy are continued to be added to the gas-fired heating furnace to prepare the melt, the automatic oscillating angle gauge 13 is adjusted to close the double-furnace stop plug 12, and the melt extraction and pressure pump 25 is turned off. After the aluminum alloy melt is prepared, and the gas-fired heating furnace liquid level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is higher than the first threshold, step e-1) or step e-2) is repeated to achieve the casting of the aluminum alloy metal product.

[0137] In the steps of double-action serial circulation of the melt and low-pressure casting, the first threshold value is 1 / 5 of the effective total height of the gas heating furnace body; the second threshold value is 1 / 4 of the effective total height of the low-pressure casting furnace body; and the third threshold value is the effective total height of the low-pressure casting furnace body. In the steps of double-action serial circulation of the melt and low-pressure casting, the liquid melt densitometer 17 is started and the density of the aluminum alloy melt in the low-pressure casting furnace under different temperature conditions is detected, and the density is coupled and compared with the density of the prepared target alloy composition melt, thereby achieving the purpose of quickly detecting the composition of the aluminum alloy melt in the low-pressure casting furnace;

[0138] f) Smoke and dust purification and removal: By controlling the opening and closing of the furnace gas exhaust brake ball valve 19, the waste smoke and exhaust gas discharged from the gas heating furnace are purified and the pressure of the waste smoke and exhaust gas in the furnace gas exhaust pipe 11 is controlled at the same time.

[0139] In a preferred embodiment of the present invention, the number of the argon generators 1 is 3, and the distance between them is 460 mm. The flow rate of the argon gas introduced into the argon generator 1 is 2.0 L·min -1 . The number of the powder refining agent inlet devices 3 is 2, and the distance between them is 510 mm. The powder refining agent inlet devices 3 are arranged on the side wall of the gas heating furnace and close to the bottom of the gas heating furnace. The powder refining agent is composed of Na3AlF6, KCl, CaCl2, TiO2, C2Cl6 and Na2SiF6, Na3AlF6 accounts for 5% of the total weight of the powder refining agent, KCl accounts for 2% of the total weight of the powder refining agent, TiO2 accounts for 20% of the total weight of the powder refining agent, C2Cl6 accounts for 50% of the total weight of the powder refining agent, Na2SiF6 accounts for 4% of the total weight of the powder refining agent, and the balance is CaCl2.

[0140] In a preferred embodiment of the present invention, the number of the ultrasonic exciters 2 is 2, and the distance between them is 420 mm. The ultrasonic excitation frequency emitted by the ultrasonic exciter 2 is 18 kHz, the ultrasonic excitation amplitude is 25 μm, the ultrasonic excitation mode is a pulse mode, and the duty cycle is 65%. The number of the grain refining powder inlet devices 4 is 2, and the distance between them is 520 mm. The grain refining powder inlet devices 4 are arranged on the side wall of the gas-fired heating furnace and close to the bottom of the gas-fired heating furnace. The grain refining powder is composed of K2TiF6, KBF4, K2ZrF6 and Sc2O3, K2TiF6 accounts for 35% of the total weight of the grain refining powder, KBF4 accounts for 28% of the total weight of the grain refining powder, K2ZrF6 accounts for 18% of the total weight of the grain refining powder, and the balance is Sc2O3.

[0141] In a preferred embodiment of the present invention, the number of the intermediate alloy feeder 5 is 1. The intermediate alloy ingot is added to the gas-fired heating furnace through the intermediate alloy feeder 5; the intermediate alloy needs to be heat-baked before being added to the gas-fired heating furnace. The heat baking temperature is 200°C and the heat baking time is 25 minutes. The purpose of heat baking is to remove oil and moisture on the surface of the intermediate alloy and improve the quality of the aluminum alloy melt. The intermediate alloy feeder 5 is arranged on the side wall of the gas-fired heating furnace, and the distance between it and the top of the gas-fired heating furnace is 320mm. The gas heater 6 is located on both sides of the upper end of the gas-fired heating furnace, the number is 2, the working temperature is 800°C, the temperature control accuracy is ±3°C, the thermal efficiency is 85%, and the gas flow rate is 75m 3 ·h -1 The melt feeding filter 7 adopts a double-layer ceramic filter screen, wherein the upper ceramic filter screen is made of ZrO2 with a pore size of 250 μm; the lower ceramic filter screen is made of Y2O3 with a pore size of 80 μm.

[0142] In a preferred embodiment of the present invention, the automatic skimmer 9 is made of graphite and has a V-shaped cross-section, with the distance between the two endpoints of the V being 660 mm. The mechanical stirrer 10 is made of silicon carbide and is installed at the top of the gas-fired furnace, extending to half the height of the aluminum alloy melt within the furnace.

[0143] In a preferred embodiment of the present invention, the material of the double furnace stop plug 12 is aluminum silicate ceramic fiber, wherein the Al2O3 content is 62%, the SiO2 content is 37.9%, and the Fe2O3 content is 0.10%. The swing angle range of the automatic oscillating angle meter 13 is 0°-60°. The automatic oscillating angle meter 13 is connected to the double furnace stop plug 12 through a mechanical structure. After the automatic oscillating angle meter 13 swings, it will drive the double furnace stop plug 12 to perform a circular motion together, thereby opening the channel between the gas heating furnace and the low-pressure casting furnace, and realizing the dynamic replenishment of the aluminum alloy melt in the low-pressure casting furnace.

[0144] In a preferred embodiment of the present invention, the low-pressure casting furnace heater 14 is made of silicon carbon rods. There are five low-pressure casting furnace heaters 14. Each heater 14 is located on the side wall of the low-pressure casting furnace, near the bottom of the furnace. The heating power of each heater 14 is 2.5 kW.

[0145] In a preferred embodiment of the present invention, the high-pressure gas introduced into the pressurized pipe 15 is dry compressed air with a humidity of 20% RH. The gas pressure in the filling stage is 0.10 MPa, and the gas pressure in the pressure-holding stage is 0.15 MPa. The riser pipe 16 is made of stainless steel and coated with a high-temperature resistant coating. The high-temperature resistant coating is composed of CaCO3, ZnO, Na2O·nSiO2 and H2O, wherein CaCO3 accounts for 8.5% of the total weight of the high-temperature resistant coating, ZnO accounts for 5.0% of the total weight of the high-temperature resistant coating, Na2O·nSiO2 accounts for 5.2% of the total weight of the high-temperature resistant coating, and the remainder is H2O. The measuring range of the liquid melt density meter 17 is 2.0 g·cm -3 -3.0g·cm -3 , with a resolution of 0.002 g·cm -3 The measurement principle is vibration tube type, the response time is 2s, a honeycomb ceramic filter is installed at the inlet of the vibration tube, the pore size of the honeycomb ceramic filter is 0.3mm, and the surface of the sensor is coated with titanium nitride coating.

[0146] In a preferred embodiment of the present invention, the sealing form of the furnace gas exhaust brake ball valve 19 is PTFE soft seal, the driving mode is pneumatic, the opening and closing reaction time of the furnace gas exhaust brake ball valve 19 is 0.1s, and the sealing grade is 0.6×10 -6 mbar·L·s -1 The inert gas introduced by the inert gas inlet 20 is a mixed gas, wherein He gas accounts for 60% by volume, Ar gas accounts for 26% by volume, and the remaining gas is CO2. The inert gas introduction flow rate is 3L·s -1 The material type of the low-pressure casting furnace side thermocouple 21 and the low-pressure casting furnace bottom thermocouple 22 is B-type thermocouple, and the thermal response time T 0.5 The temperature is 35s, the tolerance level is 1°C, and the material of the protective tube is Al2O3.

[0147] In a preferred embodiment of the present invention, the material of the furnace lining 23 of the low-pressure casting furnace is a gradient composite structure material, including a five-layer structure, wherein the material of the first layer structure in contact with the melt is alumina insulation brick with a thickness of 100 mm; the material of the second layer structure in contact with the first layer structure is silica nanoporous insulation board with a thickness of 1.5 mm; the material of the third layer structure in contact with the second layer structure is polycrystalline mullite fiber PMF with a thickness of 3.5 mm; the material of the fourth layer structure in contact with the third layer structure is diatomaceous earth with a thickness of 45 mm; the material of the fifth layer structure in contact with the fourth layer structure is zircon hollow brick with a thickness of 60 mm and a porosity of 45%. The material of the furnace lining 24 of the gas heating furnace is a gradient composite structure material, including a five-layer structure, wherein the material of the first layer structure in contact with the melt is alumina insulation brick with a thickness of 100 mm; the material of the second layer structure in contact with the first layer structure is silica nano-microporous insulation board with a thickness of 1.5 mm; the material of the third layer structure in contact with the second layer structure is polycrystalline mullite fiber PMF with a thickness of 3.5 mm; the material of the fourth layer structure in contact with the third layer structure is diatomaceous earth with a thickness of 45 mm; the material of the fifth layer structure in contact with the fourth layer structure is zircon hollow brick with a thickness of 60 mm and a porosity of 45%.

[0148] The aluminum alloy metal product in Example 3 is an aluminum alloy compartment shell, and the material is ZL114A.

[0149] Example 4

[0150] This embodiment provides a method for preparing a double-action serial circulation high-purity aluminum melt. The method is based on the double-action serial circulation high-purity aluminum melt low-pressure casting device described in Example 1. The method comprises the following steps:

[0151] a) Charging and Melting: Pure aluminum melt is added to the gas-fired heating furnace through the melt feeding filter 7. A master alloy is prepared according to the alloy composition and added to the gas-fired heating furnace through the master alloy feeder 5. The gas heater 6 is turned on and the temperature in the gas-fired heating furnace is adjusted until the master alloy is completely melted.

[0152] b) Refining and degassing: The argon generator 1 is turned on, the powder refining agent inlet 3 is opened and the powder refining agent is pressed into the gas-fired heating furnace to refine and degas the aluminum alloy melt in the gas-fired heating furnace. During the refining and degassing process, the mechanical stirrer 10 is started to mechanically stir the aluminum alloy melt. After refining and degassing, the slag formed on the surface of the aluminum alloy melt after the refining and degassing reaction is skimmed off using an automatic slag skimmer 9. During the refining and degassing step, the temperature of the aluminum alloy melt in the gas-fired heating furnace is 750° C. The stirring speed of the mechanical stirrer 10 is 800 r / min. -1 , stirring time is 20min;

[0153] c) Grain refinement: The ultrasonic vibrator 2 is turned on, the grain refinement powder feeder 4 is opened, and the grain refinement powder is pressed into the gas-fired heating furnace to perform grain refinement on the aluminum alloy melt in the gas-fired heating furnace. During the grain refinement process, the mechanical stirrer 10 is started to mechanically stir the aluminum alloy melt. After the grain refinement, the slag formed on the surface of the aluminum alloy melt after the grain refinement reaction is skimmed off using an automatic slag skimmer 9. During the grain refinement process, the temperature of the aluminum alloy melt in the gas-fired heating furnace is 780° C., and the stirring speed of the mechanical stirrer 10 is 850 rpm. -1 , stirring time is 10min;

[0154] d) Temperature adjustment and static holding: starting the low-pressure casting furnace heater 14 to adjust the temperature in the low-pressure casting furnace to a certain temperature range and maintaining the temperature for a certain time; starting the inert gas inlet 20 to introduce inert gas into the low-pressure casting furnace to provide an inert atmosphere protection for the aluminum alloy melt; during the temperature adjustment and static holding process, the temperature range of the aluminum alloy melt in the low-pressure casting furnace is 730° C., and the holding time is 24 minutes;

[0155] e) Melt double-action serial circulation and low-pressure casting: Before low-pressure casting, detect the content of aluminum alloy melt in the gas heating furnace and low-pressure casting furnace:

[0156] e-1) When the gas-fired heating furnace level gauge 8 detects that the aluminum alloy melt in the gas-fired heating furnace is above a first threshold, and the low-pressure casting furnace level gauge 18 detects that the aluminum alloy melt in the low-pressure casting furnace is above a second threshold, the automatic oscillating angle gauge 13 is adjusted to close the dual-furnace stop plug 12, and the melt extraction and pressure pump 25 is simultaneously turned off; the pressure pipe 15 is opened to allow high-pressure gas to flow into the low-pressure casting furnace; the riser pipe 16 is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to form an aluminum alloy metal product;

[0157] e-2) When the gas-fired heating furnace level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is higher than a first threshold value, and the low-pressure casting furnace level gauge 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is lower than a second threshold value, the automatic oscillating angle gauge 13 is adjusted to open the double-furnace stopper plug 12, and the melt extraction and pressure pump 25 is simultaneously turned on to achieve double-action serial circulation of the aluminum alloy melt; when the low-pressure casting furnace level gauge 18 detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is higher than a third threshold value, the automatic oscillating angle gauge 13 is adjusted to close the double-furnace stopper plug 12, and the melt extraction and pressure pump 25 is simultaneously turned off; the pressure pipe 15 is opened to introduce high-pressure gas into the low-pressure casting furnace; the liquid riser 16 is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to achieve casting and forming of aluminum alloy metal products;

[0158] e-3) When the gas-fired heating furnace liquid level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is lower than the first threshold, pure aluminum melt and master alloy are continued to be added to the gas-fired heating furnace to prepare the melt, the automatic oscillating angle gauge 13 is adjusted to close the double-furnace stop plug 12, and the melt extraction and pressure pump 25 is turned off. After the aluminum alloy melt is prepared, and the gas-fired heating furnace liquid level gauge 8 detects that the liquid level of the aluminum alloy melt in the gas-fired heating furnace is higher than the first threshold, step e-1) or step e-2) is repeated to achieve the casting of the aluminum alloy metal product.

[0159] In the steps of double-action serial circulation of the melt and low-pressure casting, the first threshold value is 1 / 5 of the effective total height of the gas heating furnace body; the second threshold value is 1 / 4 of the effective total height of the low-pressure casting furnace body; and the third threshold value is the effective total height of the low-pressure casting furnace body. In the steps of double-action serial circulation of the melt and low-pressure casting, the liquid melt densitometer 17 is started and the density of the aluminum alloy melt in the low-pressure casting furnace under different temperature conditions is detected, and the density is coupled and compared with the density of the prepared target alloy composition melt, thereby achieving the purpose of quickly detecting the composition of the aluminum alloy melt in the low-pressure casting furnace;

[0160] f) Smoke and dust purification and removal: By controlling the opening and closing of the furnace gas exhaust brake ball valve 19, the waste smoke and exhaust gas discharged from the gas heating furnace are purified and the pressure of the waste smoke and exhaust gas in the furnace gas exhaust pipe 11 is controlled at the same time.

[0161] In a preferred embodiment of the present invention, the number of the argon generators 1 is 5, and the distance between them is 480 mm. The flow rate of the argon gas introduced into the argon generator 1 is 4.5 L·min -1 . The number of the powder refining agent inlet devices 3 is 4, and the distance between each other is 600 mm. The powder refining agent inlet devices 3 are arranged on the side wall of the gas-fired heating furnace and close to the bottom of the gas-fired heating furnace. The powder refining agent is composed of Na3AlF6, KCl, CaCl2, TiO2, C2Cl6 and Na2SiF6, with Na3AlF6 accounting for 7% of the total weight of the powder refining agent, KCl accounting for 4% of the total weight of the powder refining agent, TiO2 accounting for 24% of the total weight of the powder refining agent, C2Cl6 accounting for 52% of the total weight of the powder refining agent, Na2SiF6 accounting for 6% of the total weight of the powder refining agent, and the balance being CaCl2.

[0162] In a preferred embodiment of the present invention, the number of the ultrasonic exciters 2 is 4, and the distance between them is 460 mm. The ultrasonic excitation frequency emitted by the ultrasonic exciter 2 is 30 kHz, the ultrasonic excitation amplitude is 75 μm, the ultrasonic excitation mode is a pulse mode, and the duty cycle is 80%. The number of the grain refining powder inlet devices 4 is 2, and the distance between them is 520 mm. The grain refining powder inlet devices 4 are arranged on the side wall of the gas-fired heating furnace and close to the bottom of the gas-fired heating furnace. The grain refining powder is composed of K2TiF6, KBF4, K2ZrF6 and Sc2O3, K2TiF6 accounts for 38% of the total weight of the grain refining powder, KBF4 accounts for 32% of the total weight of the grain refining powder, K2ZrF6 accounts for 20% of the total weight of the grain refining powder, and the balance is Sc2O3.

[0163] In a preferred embodiment of the present invention, the number of the intermediate alloy feeder 5 is 1. The intermediate alloy ingot is added to the gas heating furnace through the intermediate alloy feeder 5; the intermediate alloy needs to be heat-baked before being added to the gas heating furnace. The heat baking temperature is 300°C and the heat baking time is 35 minutes. The purpose of heat baking is to remove oil and moisture on the surface of the intermediate alloy and improve the quality of the aluminum alloy melt. The intermediate alloy feeder 5 is arranged on the side wall of the gas heating furnace, and the distance between it and the top of the gas heating furnace is 400mm. The gas heaters 6 are located on both sides of the upper end of the gas heating furnace, the number is 62, the working temperature is 950°C, the temperature control accuracy is ±3°C, the thermal efficiency is 95%, and the gas flow rate is 120m 3 ·h -1 The melt feeding filter 7 adopts a double-layer ceramic filter screen, wherein the upper ceramic filter screen is made of ZrO2 with a pore size of 450 μm; the lower ceramic filter screen is made of Y2O3 with a pore size of 120 μm.

[0164] In a preferred embodiment of the present invention, the automatic skimmer 9 is made of graphite and has a V-shaped cross-section, with the distance between the two endpoints of the V being 660 mm. The mechanical stirrer 10 is made of silicon carbide and is installed at the top of the gas-fired furnace, extending to 3 / 5 of the height of the aluminum alloy melt within the furnace.

[0165] In a preferred embodiment of the present invention, the material of the double furnace stop plug 12 is aluminum silicate ceramic fiber, wherein the Al2O3 content is 63%, the SiO2 content is 36.9%, and the Fe2O3 content is 0.10%. The swing angle range of the automatic oscillating angle meter 13 is 0°-60°. The automatic oscillating angle meter 13 is connected to the double furnace stop plug 12 through a mechanical structure. After the automatic oscillating angle meter 13 swings, it will drive the double furnace stop plug 12 to perform a circular motion together, thereby opening the channel between the gas heating furnace and the low-pressure casting furnace, and realizing the dynamic replenishment of the aluminum alloy melt in the low-pressure casting furnace.

[0166] In a preferred embodiment of the present invention, the low-pressure casting furnace heater 14 is made of silicon carbon rods. There are eight low-pressure casting furnace heaters 14 . Each heater 14 is located on the side wall of the low-pressure casting furnace, near the bottom of the furnace. The heating power of each heater 14 is 4.0 kW.

[0167] In a preferred embodiment of the present invention, the high-pressure gas introduced into the pressurized pipe 15 is dry compressed air with a humidity of 30% RH. The gas pressure in the filling stage is 0.15 MPa, and the gas pressure in the pressure-holding stage is 0.25 MPa. The material of the rising pipe 16 is stainless steel, and the surface is coated with a high-temperature resistant coating. The high-temperature resistant coating is composed of CaCO3, ZnO, Na2O·nSiO2 and H2O, wherein CaCO3 accounts for 9.5% of the total weight of the high-temperature resistant coating, ZnO accounts for 6.0% of the total weight of the high-temperature resistant coating, Na2O·nSiO2 accounts for 6.4% of the total weight of the high-temperature resistant coating, and the balance is H2O. The measuring range of the liquid melt density meter 17 is 2.0 g·cm -3 -3.0g·cm -3 , with a resolution of 0.004 g·cm -3 The measurement principle is vibration tube type, the response time is 5s, a honeycomb ceramic filter is installed at the inlet of the vibration tube, the pore size of the honeycomb ceramic filter is 0.5mm, and the sensor surface is coated with titanium nitride coating.

[0168] In a preferred embodiment of the present invention, the sealing form of the furnace gas exhaust brake ball valve 19 is PTFE soft seal, the driving mode is pneumatic, the opening and closing reaction time of the furnace gas exhaust brake ball valve 19 is 0.5s, and the sealing grade is 1.2×10 -6 mbar·L·s -1 The inert gas introduced by the inert gas inlet 20 is a mixed gas, wherein He gas accounts for 68% by volume, Ar gas accounts for 30% by volume, and the remaining gas is CO2. The inert gas flow rate is 3.5 L·s -1The material type of the low-pressure casting furnace side thermocouple 21 and the low-pressure casting furnace bottom thermocouple 22 is B-type thermocouple, and the thermal response time T 0.5 The temperature is 60s, the tolerance level is 2℃, and the material of the protective tube is Al2O3.

[0169] In a preferred embodiment of the present invention, the material of the furnace lining 23 of the low-pressure casting furnace is a gradient composite structure material, including a five-layer structure, wherein the material of the first layer structure in contact with the melt is alumina insulation brick with a thickness of 120 mm; the material of the second layer structure in contact with the first layer structure is silica nanoporous insulation board with a thickness of 2.5 mm; the material of the third layer structure in contact with the second layer structure is polycrystalline mullite fiber PMF with a thickness of 6.0 mm; the material of the fourth layer structure in contact with the third layer structure is diatomaceous earth with a thickness of 60 mm; the material of the fifth layer structure in contact with the fourth layer structure is zircon hollow brick with a thickness of 100 mm and a porosity of 60%. The material of the furnace lining 24 of the gas heating furnace is a gradient composite structure material, including a five-layer structure, wherein the material of the first layer structure in contact with the melt is alumina insulation brick with a thickness of 120 mm; the material of the second layer structure in contact with the first layer structure is silica nano-microporous insulation board with a thickness of 2.5 mm; the material of the third layer structure in contact with the second layer structure is polycrystalline mullite fiber PMF with a thickness of 6.0 mm; the material of the fourth layer structure in contact with the third layer structure is diatomaceous earth with a thickness of 60 mm; the material of the fifth layer structure in contact with the fourth layer structure is zircon hollow brick with a thickness of 100 mm and a porosity of 60%.

[0170] The aluminum alloy metal product in Example 4 is an aluminum alloy impeller made of A356.

[0171] Table 1 Comparative table of properties of aluminum alloy metal products prepared in Examples 2-4

[0172]

[0173] Table 2 Comparison of the as-cast grain size and room temperature mechanical properties of the aluminum alloy metal products prepared in Examples 2-4

[0174]

[0175] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A double-action serial circulation high-purity aluminum melt low-pressure casting device, wherein: The low-pressure casting device comprises a gas heating furnace and a low-pressure casting furnace; the gas heating furnace is arranged on one side of the low-pressure casting furnace, and the gas heating furnace and the low-pressure casting furnace are connected via a double-furnace stop plug (12); The gas heating furnace comprises an intermediate alloy feeder (5), a gas heater (6), a melt feeding filter (7), a gas heating furnace level gauge (8) and a melt extraction pressure pump (25); The intermediate alloy feeder (5) and the gas heater (6) are arranged on the side wall of the gas heating furnace; the melt feeding filter (7) is arranged on the top of the gas heating furnace; the gas heating furnace level gauge (8) is arranged on the top of the gas heating furnace and extends to the inside of the gas heating furnace; the melt extraction pressure pump (25) is arranged inside the gas heating furnace; The low-pressure casting furnace includes an automatic oscillating angle meter (13), a low-pressure casting furnace heater (14), a pressurizing pipe (15), a liquid riser (16), a low-pressure casting furnace liquid level meter (18), and an inert gas inlet (20); The low-pressure casting furnace heater (14) and the inert gas inlet (20) are arranged on the side wall of the low-pressure casting furnace; the pressurizing pipe (15) is arranged on the top of the low-pressure casting furnace; the automatic oscillating angle meter (13), the liquid riser (16) and the low-pressure casting furnace liquid level meter (18) are arranged on the top of the low-pressure casting furnace and extend into the interior of the low-pressure casting furnace; the automatic oscillating angle meter (13) is connected to the double furnace stop plug (12); The gas-fired heating furnace further comprises an argon generator (1), an ultrasonic vibrator (2), a powder refining agent inlet (3) and a grain refining powder inlet (4); the argon generator (1) and the ultrasonic vibrator (2) are arranged at the bottom of the gas-fired heating furnace; the powder refining agent inlet (3) and the grain refining powder inlet (4) are arranged on the side wall of the gas-fired heating furnace; The gas heating furnace further comprises an automatic skimmer (9) and a mechanical stirrer (10); the automatic skimmer (9) and the mechanical stirrer (10) are arranged on the top of the gas heating furnace and extend into the interior of the gas heating furnace; The gas heating furnace further comprises a furnace gas exhaust pipe (11); an inlet of the furnace gas exhaust pipe (11) is arranged at the top of the gas heating furnace, and the furnace gas exhaust pipe (11) is arranged outside the furnace lining (23) of the low-pressure casting furnace; The low-pressure casting furnace comprises a liquid melt density meter (17), a low-pressure casting furnace side end thermocouple (21), and a low-pressure casting furnace bottom end thermocouple (22); the low-pressure casting furnace side end thermocouple (21) is arranged on the side wall of the low-pressure casting furnace; the liquid melt density meter (17) is arranged on the top of the low-pressure casting furnace and extends to the interior of the low-pressure casting furnace; the low-pressure casting furnace bottom end thermocouple (22) is arranged at the bottom of the low-pressure casting furnace; The low-pressure casting furnace further comprises a furnace gas exhaust brake ball valve (19); the furnace gas exhaust brake ball valve (19) is arranged at the outlet of the furnace gas exhaust pipe (11).

2. The low-pressure casting device according to claim 1, wherein: The number of the argon generators (1) is 3-5, and the distance between them is ≥450 mm; the flow rate of the argon gas introduced into the argon generator (1) is 2.0 L·min -1 -4.5L·min -1 ; And / or, the number of the powder refining agent feeders (3) is 2-4, and the distance between each other is ≥500 mm; the powder refining agent feeders (3) are arranged on the side wall of the gas heating furnace and close to the bottom of the gas heating furnace; the powder refining agent feeders (3) are used to directly press the powder refining agent into the interior of the aluminum alloy melt; the powder refining agent includes Na3AlF6, KCl, CaCl2, TiO2, C2Cl6 and Na2SiF6; Among them, the mass of Na3AlF6 accounts for 5%-7% of the total mass of the powder refining agent, the mass of KCl accounts for 2%-4% of the total mass of the powder refining agent, the mass of TiO2 accounts for 20%-24% of the total mass of the powder refining agent, the mass of C2Cl6 accounts for 50%-52% of the total mass of the powder refining agent, the mass of Na2SiF6 accounts for 4%-6% of the total mass of the powder refining agent, and the balance is CaCl2; And / or, the number of the ultrasonic exciters (2) is 2-4, and the distance between each other is ≥400 mm; the ultrasonic exciter (2) emits an ultrasonic excitation frequency of 18 kHz-30 kHz, an ultrasonic excitation amplitude of 25 μm-75 μm, an ultrasonic excitation mode of a pulse mode, and a duty cycle of 65%-80%; And / or, the number of the grain refining powder feeders (4) is 1-3, and the distance between each other is ≥500mm; the grain refining powder feeders (4) are arranged on the side wall of the gas-fired heating furnace and close to the bottom of the gas-fired heating furnace; the grain refining powder feeders (4) are used to directly press the grain refining powder into the interior of the aluminum alloy melt; the grain refining powder includes K2TiF6, KBF4, K2ZrF6 and Sc2O3; wherein the mass of K2TiF6 accounts for 35%-38% of the total mass of the grain refining powder, the mass of KBF4 accounts for 28%-32% of the total mass of the grain refining powder, the mass of K2ZrF6 accounts for 18%-20% of the total mass of the grain refining powder, and the balance is Sc2O3.

3. The low-pressure casting device according to claim 2, wherein: The intermediate alloy feeder (5) is arranged on the side wall of the gas heating furnace, and the distance between the intermediate alloy feeder (5) and the top of the gas heating furnace is ≥300 mm; And / or, the gas heater (6) is arranged on the side wall of the gas heating furnace and close to the top of the gas heating furnace; the number of the gas heaters (6) is 2-6; the operating temperature of the gas heater (6) is 650°C-1250°C, the temperature control accuracy is less than ±6°C, the thermal efficiency is 84%-96%, and the gas flow rate is 65m 3 ·h -1 -125m 3 ·h -1 ; And / or, the melt feeding filter (7) adopts a double-layer ceramic filter screen, wherein the material of the upper ceramic filter screen is ZrO2, and the pore size is 250μm-450μm; the material of the lower ceramic filter screen is Y2O3, and the pore size is 80μm-120μm; And / or, the mechanical stirrer (10) is arranged on the top of the gas-fired heating furnace and extends to 1 / 3-2 / 3 of the height of the aluminum alloy melt in the gas-fired heating furnace; And / or, the swing angle range of the automatic swing angle meter (13) is 0°-60°; And / or, the number of the low-pressure casting furnace heaters (14) is 5-8; the low-pressure casting furnace heaters (14) are arranged on the side wall of the low-pressure casting furnace and close to the bottom of the low-pressure casting furnace; the heating power of the low-pressure casting furnace heaters (14) is 2.5kW-4.0kW; And / or, the high-pressure gas introduced into the pressurized pipe (15) is dry compressed air with a humidity of ≤30% RH, the pressure of the gas introduced during the filling stage is 0.10 MPa-0.15 MPa, and the pressure of the gas introduced during the pressure holding stage is 0.15 MPa-0.25 MPa; And / or, the inert gas introduced into the inert gas inlet (20) is a mixed gas, wherein the volume percentage of He gas to the total volume of the mixed gas is 60%-68%, the volume percentage of Ar gas to the total volume of the mixed gas is 26%-30%, and the volume percentage of CO2 to the total volume of the mixed gas is 2%-14%; the inert gas introduction flow rate is 1.5 L·s -1 -4.0L·s -1 .

4. The low-pressure casting device according to claim 1, wherein: The gas heating furnace further includes a furnace lining (24) of the gas heating furnace, and the low-pressure casting furnace further includes a furnace lining (23) of the low-pressure casting furnace; The lining (23) of the low-pressure casting furnace is made of a gradient composite structure material, including a five-layer structure, wherein the material of the first layer structure in contact with the melt is alumina insulation brick with a thickness of 100mm-120mm; the material of the second layer structure in contact with the first layer structure is silicon dioxide nanoporous insulation board with a thickness of 1.5mm-2.5mm; the material of the third layer structure in contact with the second layer structure is polycrystalline mullite fiber PMF with a thickness of 3.5mm-6.0mm; the material of the fourth layer structure in contact with the third layer structure is diatomaceous earth with a thickness of 45mm-60mm; the material of the fifth layer structure in contact with the fourth layer structure is zircon hollow brick with a thickness of 60mm-100mm and a porosity of 45%-60%; The lining (24) of the gas heating furnace is made of a gradient composite structure material, including a five-layer structure, wherein the material of the first layer structure in contact with the melt is alumina insulation brick with a thickness of 100mm-120mm; the material of the second layer structure in contact with the first layer structure is silicon dioxide nano-microporous insulation board with a thickness of 1.5mm-2.5mm; the material of the third layer structure in contact with the second layer structure is polycrystalline mullite fiber PMF with a thickness of 3.5mm-6.0mm; the material of the fourth layer structure in contact with the third layer structure is diatomaceous earth with a thickness of 45mm-60mm; the material of the fifth layer structure in contact with the fourth layer structure is zircon hollow brick with a thickness of 60mm-100mm and a porosity of 45%-60%.

5. A method for preparing a double-action serial circulation high-purity aluminum melt, the method being implemented based on the double-action serial circulation high-purity aluminum melt low-pressure casting device according to any one of claims 1 to 4, the method comprising the following steps: 1) Charging and melting: pure aluminum melt is added into the gas heating furnace through the melt feeding filter (7), the intermediate alloy is prepared according to the alloy composition, and the intermediate alloy is added into the gas heating furnace through the intermediate alloy feeder (5); the gas heater (6) is turned on and the temperature in the gas heating furnace is adjusted until the intermediate alloy is completely melted; 2) Temperature adjustment and standing: start the low-pressure casting furnace heater (14), adjust the temperature in the low-pressure casting furnace to a certain temperature range and keep it warm for a certain time; open the inert gas inlet (20), and introduce inert gas into the low-pressure casting furnace to provide inert atmosphere protection for the aluminum alloy melt; 3) Melt double-action serial circulation and low-pressure casting: Before low-pressure casting, detect the content of aluminum alloy melt in the gas heating furnace and low-pressure casting furnace: 3-1) When the gas heating furnace level gauge (8) detects that the liquid level of the aluminum alloy melt in the gas heating furnace is higher than a first threshold value, and the low-pressure casting furnace level gauge (18) detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is higher than a second threshold value, the automatic swing angle meter (13) is adjusted to close the double furnace stop plug (12), and the melt extraction pressure pump (25) is closed at the same time; the pressure pipe (15) is opened to introduce high-pressure gas into the low-pressure casting furnace; the liquid riser (16) is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to achieve casting and forming of aluminum alloy metal products; 3-2) When the gas heating furnace level gauge (8) detects that the liquid level of the aluminum alloy melt in the gas heating furnace is higher than the first threshold value, and the low-pressure casting furnace level gauge (18) detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is lower than the second threshold value, the automatic swing angle meter (13) is adjusted to make the double furnace stop plug (12) in the open state, and the melt extraction pressure pump (25) is turned on at the same time to achieve double-action serial circulation of the aluminum alloy melt; when the low-pressure casting furnace level gauge (18) detects that the liquid level of the aluminum alloy melt in the low-pressure casting furnace is higher than the third threshold value, the automatic swing angle meter (13) is adjusted to make the double furnace stop plug (12) in the closed state, and the melt extraction pressure pump (25) is turned off at the same time; the pressure pipe (15) is opened to introduce high-pressure gas into the low-pressure casting furnace; the liquid riser (16) is opened, and the aluminum alloy melt in the low-pressure casting furnace is compressed by the high-pressure gas to achieve casting and forming of aluminum alloy metal products; 3-3) When the gas heating furnace level gauge (8) detects that the liquid level of the aluminum alloy melt in the gas heating furnace is lower than the first threshold, pure aluminum melt and intermediate alloy are continuously added to the gas heating furnace to prepare the melt, the automatic swing angle meter (13) is adjusted to make the double furnace stop plug (12) in the closed state, and the melt extraction pressure pump (25) is turned off at the same time; after the aluminum alloy melt preparation is completed, and the gas heating furnace level gauge (8) detects that the liquid level of the aluminum alloy melt in the gas heating furnace is higher than the first threshold, step 3-1) or step 3-2) is repeated to achieve the casting of the aluminum alloy metal product; in, The first threshold is 1 / 5 of the effective total height of the gas heating furnace body; the second threshold is 1 / 4 of the effective total height of the low-pressure casting furnace body; and the third threshold is the effective total height of the low-pressure casting furnace body.

6. The preparation method according to claim 5, wherein In the step of temperature adjustment and standing, the temperature of the aluminum alloy melt in the low-pressure casting furnace during the temperature adjustment and standing process ranges from 710° C. to 730° C., and the holding time is from 16 min to 24 min.

7. The preparation method according to claim 5, wherein The following steps are also included before the steps of double-action serial circulation of the melt and low-pressure casting: 1') Refining and degassing: Turn on the argon generator (1), open the powder refining agent inlet (3) and press the powder refining agent into the gas heating furnace to refine and degas the aluminum alloy melt in the gas heating furnace. During the refining and degassing process, start the mechanical stirrer (10) to mechanically stir the aluminum alloy melt. After refining and degassing, use the automatic slag skimmer (9) to skim off the slag formed on the surface of the aluminum alloy melt after the refining and degassing reaction. 1'') Grain refinement: Turn on the ultrasonic vibrator (2), open the grain refinement powder inlet (4) and press the grain refinement powder into the gas-fired heating furnace to perform grain refinement on the aluminum alloy melt in the gas-fired heating furnace. During the grain refinement process, start the mechanical stirrer (10) to mechanically stir the aluminum alloy melt. After the grain refinement, use the automatic slag skimmer (9) to skim off the slag formed on the surface of the aluminum alloy melt after the grain refinement reaction. In the refining and degassing step, the temperature of the aluminum alloy melt in the gas heating furnace is 720°C-750°C during refining and degassing; the stirring speed of the mechanical stirrer (10) is 450r·min -1 -800r·min -1 , stirring time is 14min-20min; In the step of grain refinement, the temperature of the aluminum alloy melt in the gas heating furnace is 740°C-780°C during grain refinement; the stirring speed of the mechanical stirrer (10) is 550 r·min -1 -850r·min -1 , stirring time is 10min-15min.

8. The preparation method according to any one of claims 5 to 7, wherein The method further comprises the steps of: 4) Smoke and dust purification and removal: By controlling the opening and closing of the furnace gas exhaust brake ball valve (19), the waste smoke and exhaust gas discharged from the gas heating furnace are purified and the pressure of the waste smoke and exhaust gas in the furnace gas exhaust pipe (11) is controlled at the same time.

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