Multi-cavity cooperative positive pressure protection system for 7065 aluminum alloy smelting and casting and oxidation inhibition control method

Abstract

The invention discloses a multi-cavity cooperative positive pressure protection system for 7065 aluminum alloy smelting and casting and an oxidation inhibition control method, and relates to the technical field of casting. The multi-cavity cooperative positive pressure protection system comprises a smelting furnace, a heat preservation furnace and an online degassing device which are arranged in sequence; the adjacent chambers are connected through a sealing launder to form a relatively closed system; the smelting furnace, the holding furnace and the online degassing device are respectively provided with an independent inert gas closed-loop control system; and the inert gas closed-loop control system is used for independently supplying gas to each chamber and detecting the pressure value of the chamber. A positive pressure environment in a specific range is established and maintained in a key process cavity, and oxidation of 7065 aluminum alloy melt is inhibited synergistically, so that the defects of an oxidation film in a cast ingot are radically treated.

Description

Technical Field

[0001] This invention relates to the field of casting technology, and in particular to a multi-chamber synergistic positive pressure protection system and oxidation inhibition control method for 7065 aluminum alloy melting and casting. Background Technology

[0002] High-strength aluminum alloys such as 7065, due to their high content of reactive elements (such as Zn and Mg), readily react with oxygen and water vapor in the air during smelting, transportation, and processing, generating oxides. If these oxides are incorporated into the melt, they form so-called "oxide film" defects, causing ingots to be scrapped during fracture inspection, resulting in low yield and severely restricting product quality and production costs.

[0003] Existing technologies typically employ localized protection measures, such as applying a covering agent to the melt surface or installing an argon hood above the flow channel. However, these methods have significant shortcomings: (1) They are localized and passive: they can only protect specific areas and cannot form a continuous and effective protective barrier along the entire melt flow path. Air can easily intrude at transfer points, dumping points, and equipment interfaces. (2) The protective effect is unstable: the covering agent may introduce new inclusions, and the argon hood is prone to failure due to operational disturbances, making it difficult to ensure the continuous uniformity of the protective atmosphere. (3) The problem of "air entrainment" remains unresolved: traditional open or semi-open operations cannot prevent the oxide scale already formed on the surface from being entrained into the melt due to melt impact, turbulence, etc. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-chamber synergistic positive pressure protection system and oxidation inhibition control method for 7065 aluminum alloy melting and casting. By establishing and maintaining a positive pressure environment within a specific range in the key process chambers, the oxidation of 7065 aluminum alloy melt is synergistically inhibited, thereby eliminating the oxide film defects inside the ingot.

[0005] To achieve the above objectives, the present invention provides a multi-chamber cooperative positive pressure protection system for 7065 aluminum alloy melting and casting, comprising a melting furnace, a holding furnace, and an online degassing device arranged in sequence; adjacent chambers are connected by a sealed flow channel to form a relatively closed system; the melting furnace, the holding furnace, and the online degassing device are each equipped with an independent inert gas closed-loop control system; the inert gas closed-loop control system independently supplies gas to each chamber and detects the chamber pressure value.

[0006] Preferably, a flow rate monitoring device is installed inside the sealed flow channel. The flow rate monitoring device is electrically connected to the inert gas closed-loop control system and can dynamically adjust the gas intake according to the monitored melt flow rate.

[0007] Preferably, the inert gas closed-loop control system includes an intake system and a pressure detection system. The pressure detection system includes pressure sensors installed in the corresponding chambers. Multiple pressure sensors are provided and are respectively located in different positions in each chamber.

[0008] Preferably, pressure gauges are installed at both ends of the sealed flow channel.

[0009] Preferably, the sealing flow channel has a uniform cross-section, and the turning point of the sealing flow channel adopts a large radius of curvature bend, with the radius of curvature being greater than five times the diameter of the sealing flow channel.

[0010] A control method for oxidation inhibition using any of the above-mentioned multi-chamber synergistic positive pressure protection systems includes the following steps: S1, smelting process: 7065 aluminum alloy raw material is smelted in a smelting furnace, inert gas is introduced into the furnace chamber, and the pressure inside the smelting furnace is maintained at a slightly positive pressure state through an inert gas closed-loop control system; S2, heat preservation process: the smelted aluminum alloy melt is transferred to a heat preservation furnace through a sealed flow channel, inert gas is introduced into the sealed furnace chamber of the heat preservation furnace, and the pressure inside the heat preservation furnace is maintained at a slightly positive pressure state through an inert gas closed-loop control system, and the pressure inside the heat preservation furnace is not lower than the pressure of the smelting furnace in step S1; S3, Refining Process: The heat-insulated aluminum alloy melt is introduced into the sealed reaction chamber of the online degassing device through a sealed flow channel. In addition to blowing refining gas into the melt through a rotating nozzle, inert gas is continuously introduced into the top space of the reaction chamber to maintain the internal pressure of the online degassing device at a positive pressure state, and the pressure inside the online degassing device is not lower than the pressure of the holding furnace in S2; S4, Casting Process: The aluminum alloy melt refined by the online degassing device is cast into ingots; wherein, the melting furnace, holding furnace, and online degassing device are connected in sequence through a sealed flow channel to form a relatively closed system, and the chamber pressure along the melt flow direction shows a step-like increase or a uniform distribution.

[0011] Preferably, the chamber pressures of the smelting furnace, holding furnace, and online degassing device increase in a stepwise manner along the melt flow direction.

[0012] Preferably, the pressure range inside the smelting furnace is 0.1 Pa to 30 Pa; the pressure range inside the holding furnace is 1 Pa to 35 Pa; the pressure range inside the online degassing device is 2 Pa to 45 Pa; the pressure difference between adjacent chambers must meet the following condition: ΔP target = K × V² + ΔP base; where ΔP target is the target gas pressure difference required between adjacent chambers; V: the melt flow rate detected in real time by the flow rate monitoring device; K: the flow rate coefficient; ΔP base: the minimum safe gas pressure difference.

[0013] Preferably, the inert gas is argon with a purity of not less than 99.99%.

[0014] Preferably, the flow velocity of the aluminum alloy melt in the sealed flow channel is controlled at 0.1m / s-0.2m / s.

[0015] The present invention has the following beneficial effects: (1) The transformation from “local passive protection” to “global active defense” has systematically cut off the root cause of oxide film defects through multi-chamber collaborative positive pressure control, which is far superior to any single equipment improvement.

[0016] (2) This method can greatly reduce or even completely eliminate the problem of excessive defects caused by oxide film, and can reduce the scrap rate of oxide film of 7065 aluminum alloy ingot from 30% of the traditional method to less than 5%.

[0017] (3) Closed-loop control based on pressure sensor makes the protective atmosphere stable and controllable, less affected by human operation factors, which is conducive to the stable and mass production of high-quality ingots.

[0018] (4) It significantly reduces the scrap rate, saves huge production costs and energy consumption, and enhances product competitiveness. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a multi-chamber cooperative positive pressure protection system for 7065 aluminum alloy melting and casting according to the present invention.

[0020] In the diagram, 1 is the smelting furnace, 2 is the holding furnace, 3 is the online degassing device, and 4 is the sealing trough. Detailed Implementation

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] like Figure 1 As shown, a multi-chamber coordinated positive pressure protection system for 7065 aluminum alloy melting and casting includes a melting furnace 1, a holding furnace 2, and an online degassing device 3 arranged sequentially. Adjacent chambers are connected by sealed flow channels 4 to form a relatively closed system. The melting furnace 1, holding furnace 2, and online degassing device 3 are each equipped with an independent inert gas closed-loop control system; the inert gas closed-loop control system independently supplies gas to each chamber and detects the chamber pressure value.

[0023] The sealed flow channel 4 features a constant cross-section design, which avoids velocity variations caused by changes in cross-section, thereby preventing localized pressure drops. Large-radius bends are used at the turns of the sealed flow channel 4, with a radius of curvature greater than five times the diameter of the sealed flow channel, to reduce flow resistance and localized pressure losses.

[0024] The inert gas closed-loop control system includes an intake system and a pressure detection system. The intake system includes an intake valve installed at the intake port of the corresponding chamber and an inert gas supply device connected to the intake valve; the inert gas supply device supplies inert gas to the corresponding chamber. The inert gas used in this invention is argon with a purity of not less than 99.99%, which ensures that the inert gas contains very little oxygen and water vapor, and will not cause oxidation of the aluminum alloy melt. The pressure detection system includes multiple pressure sensors installed in the corresponding chambers, each located at a different position in each chamber, to ensure accurate monitoring of the pressure distribution within the chambers.

[0025] The number of pressure sensors can be set reasonably according to needs. The principle for setting pressure sensors in this embodiment is as follows: 1) Divide the chamber into three functional zones, assigning weights according to their importance: Core zone (directly above the melt surface, 60%): Directly reflects the pressure at the melt-gas interface, a key area for inhibiting oxidation, and has the highest weight. Transition zone (middle of the chamber, 30%): Reflects the overall pressure trend of the chamber, and has the next highest weight. Edge zone (furnace wall, corners, 10%): Greatly affected by local disturbances, and has the lowest weight. Calculation formula: P 腔室 =0.6×`P 核心区 +0.3×`P 过渡区 +0.1×`P 边缘区； Wherein, the `P region is the arithmetic mean of all sensor detection values ​​within that region.

[0026] 2) Outlier rejection mechanism. When the difference between the value detected by a certain sensor and that of other sensors in the same area exceeds 2Pa (set according to the pressure fluctuation range allowed by the process), it is judged as an outlier and rejected to avoid interfering with the results.

[0027] For example, the detection values ​​of the three sensors in the core area are 25Pa, 26Pa, and 30Pa. Since the difference between 30Pa and the other values ​​exceeds 2Pa, the average value of the core area after removing 30Pa is (25+26) / 2=25.5Pa.

[0028] 3) Dynamic filtering correction. A "sliding window filter" is applied to the fused pressure value to eliminate instantaneous jumps caused by melt disturbances or gas flow fluctuations: P 最终 = By using weighted averaging to weaken instantaneous anomalies, the stable state of chamber pressure is more accurately reflected.

[0029] A flow rate monitoring device is installed inside the sealed flow channel 4. This device is electrically connected to the inert gas closed-loop control system and can dynamically adjust the gas intake based on the monitored melt flow rate. The flow rate monitoring device is preferably a non-contact detection device, such as a laser Doppler velocimeter, electromagnetic induction velocimeter, or image processing velocimeter. It is installed in the straight section of the sealed flow channel 4 (avoiding bends or changes in cross-section) and located in the middle of two adjacent chambers to ensure that the detected flow rate accurately reflects the melt flow state between the two chambers. For example, one flow rate monitoring device can be installed in the middle of the sealed flow channel 4 between the melting furnace 1 and the holding furnace 2, and another device can be installed in the middle of the sealed flow channel 4 between the holding furnace 2 and the online degassing device 3, corresponding to the two melt flow paths respectively. The flow rate monitoring device is electrically connected to the controller of the inert gas closed-loop control system via a data transmission line, transmitting the detected flow rate signal (such as a 4-20mA current signal or digital signal) to the control system in real time. By detecting the flow rate, the inert gas pressure can be dynamically adjusted to avoid flow rate fluctuations that could cause the sealed flow channel 4 to draw in gas.

[0030] Pressure gauges 8 are installed at both ends of the sealed flow channel 4 to monitor the pressure difference between the two ends of the flow channel and ensure that the pressure distribution meets the design requirements.

[0031] A control method for oxidation inhibition using the above-mentioned multi-chamber synergistic positive pressure protection system includes the following steps: S1. Smelting process: 7065 aluminum alloy raw material is smelted in smelting furnace 1. Inert gas is introduced into the furnace chamber of smelting furnace 1. The pressure inside smelting furnace 1 is maintained at a slightly positive pressure state of 0.1Pa-30Pa through the inert gas closed-loop control system.

[0032] S2, Heat preservation process: The molten aluminum alloy is transferred to the heat preservation furnace 2 through the sealed flow channel 4. Inert gas is introduced into the sealed furnace chamber of the heat preservation furnace 2. The pressure inside the heat preservation furnace 2 is maintained at a slightly positive pressure of 1Pa-35Pa through the inert gas closed-loop control system, and the pressure inside the heat preservation furnace 2 is not lower than the pressure of the smelting furnace 1 in S1.

[0033] S3, Refining process: The heat-insulated aluminum alloy melt is introduced into the sealed reaction chamber of the online degassing device 3 through the sealed flow channel 4. In addition to blowing refining gas into the melt through the rotating nozzle, inert gas is continuously introduced into the top space of the reaction chamber to maintain the positive pressure state of the online degassing device 3 at 2Pa-45Pa, and the pressure inside the online degassing device 3 is not lower than the pressure of the heat-insulating furnace 2 in S2.

[0034] S4: Casting process: The aluminum alloy melt refined by the online degassing device 3 is cast into ingots.

[0035] Among them, the smelting furnace 1, the holding furnace 2, and the online degassing device 3 are connected in sequence through the sealed flow channel 4 to form a relatively closed system, and the chamber pressure along the melt flow direction shows a step-like increase or a uniform distribution.

[0036] Preferably, the chamber pressures of the smelting furnace 1, holding furnace 2, and online degassing device 3 increase in a stepwise manner along the melt flow direction. The melt flow generates a "dragging effect," which creates negative pressure zones in localized areas of the sealed flow channel 4 (especially at bends and areas with slight cross-sectional changes where fluid velocity increases). Even if the overall system is set to positive pressure (i.e., balanced pressure distribution), the "dragging effect" of the melt flow will still cause localized negative pressure, disrupting the inert gas protective atmosphere. Therefore, a stepwise increase in chamber pressure is required among the smelting furnace 1, holding furnace 2, and online degassing device 3 along the melt flow direction. This increasing pressure difference creates a "positive pressure gradient" within the sealed flow channel 4, offsetting any potential localized negative pressure generated by the melt flow.

[0037] Selection of Melt Flow Rate Range: When the melt flow rate exceeds 0.2 m / s, the "dragging effect" generated by the flow intensifies. This necessitates a larger pressure difference between adjacent chambers, which not only increases the burden on the equipment but also causes rapid airflow fluctuations, leading to equipment vibration, affecting its sealing, increasing the risk of external gas entrainment, and consequently, oxidation. When the melt flow rate is below 0.1 m / s, although the pressure difference requirement is reduced (no need to deal with the strong dragging effect), the residence time of the melt in the ladle is prolonged. This may cause a drop in melt temperature, affecting subsequent casting quality, and excessively low flow rates do not meet the efficiency requirements of industrial production. Therefore, controlling the flow rate within the range of 0.1 m / s to 0.2 m / s minimizes local pressure fluctuations, allowing adjacent chambers to maintain only a small pressure difference, thus avoiding negative pressure in the ladle and ensuring production efficiency.

[0038] The pressure difference between adjacent chambers (such as smelting furnace 1 and holding furnace 2, and holding furnace 2 and online degassing device 3) is not a fixed value and needs to be dynamically adjusted according to the flow rate. The core objective is to prevent the sealed flow channel 4 from "sucking in air".

[0039] Linked adjustment of flow rate and air pressure difference: When the flow rate monitoring device detects that the melt flow rate is too high (close to 0.2 m / s), the inert gas closed-loop control system will automatically increase the air intake of the downstream chamber, increase the pressure difference between adjacent chambers (e.g., from 3 Pa to 5 Pa), strengthen the positive pressure gradient, and suppress the generation of local negative pressure. When the flow rate is too low (close to 0.1 m / s), the pressure difference can be appropriately reduced to avoid excessive positive pressure leading to increased system energy consumption or damage to sealing components. The reason is that the melt flow will drive the inert gas flow rate in the flow channel to increase synchronously. According to Bernoulli's principle, the increase in gas flow rate will cause the local pressure in the flow channel to drop. If the pressure difference between adjacent chambers is still maintained at 3 Pa, the local pressure may drop below atmospheric pressure, forming a negative pressure and drawing in air. Therefore, it is necessary to increase the air intake of the downstream chamber to raise the pressure difference to 5 Pa. The stronger "positive pressure gradient" (downstream pressure > upstream pressure) will offset the pressure drop caused by the increase in gas flow rate, ensuring that the sealed flow channel 4 is always under positive pressure and suppressing the generation of local negative pressure. When the flow rate is low (close to 0.1 m / s), the gas flow rate driven by the melt slows down, and the gas pressure drop is reduced. If a high pressure difference (such as 5 Pa) is maintained at this time, the overall pressure in the flow channel will be too high. On the one hand, this will increase the consumption of inert gas and increase the system energy consumption. On the other hand, the excessive positive pressure will put additional pressure on the interface, valve and other components of the sealed flow channel. Long-term use may cause the seals to age or be damaged.

[0040] A flow rate monitoring device (such as a laser Doppler velocimeter) collects real-time melt flow rate data within the flow channel, converting it into an electrical signal (such as a 4-20mA current signal) and transmitting it to the control system. The control system has a built-in preset "flow rate-pressure difference matching algorithm." When the detected flow rate approaches 0.2 m / s (triggers a high flow rate threshold), the algorithm determines that the pressure difference needs to be increased and immediately sends a command to the inlet valve of the downstream chamber to increase the air intake. When the flow rate approaches 0.1 m / s (triggers a low flow rate threshold), the algorithm determines that the pressure difference can be decreased, thereby reducing the air intake. Pressure sensors monitor chamber pressure changes in real time, forming a closed loop of "flow rate monitoring → pressure regulation → pressure feedback," ensuring precise and timely adjustments and preventing excessively high or low pressure situations.

[0041] The logic of the "flow rate-pressure difference matching algorithm" is as follows: Based on the empirical formula derived from Bernoulli's principle, a direct correspondence is established between the "melt flow rate" and the "minimum required pressure difference" to ensure that there is no negative pressure inside the sealed flow channel 4.

[0042] Formula form: ΔP 目标 =K×V²+ΔP 基础 , where ΔP 目标 The target gas pressure difference (unit: Pa) required between adjacent chambers (e.g., melting furnace 1 → holding furnace 2).

[0043] V: The melt flow rate (unit: m / s) detected in real time by the flow rate monitoring device, with a value range of 0.1-0.2 m / s.

[0044] K: Flow rate coefficient (process calibration value), determined by the structure of the sealed flow channel 4 (such as diameter and radius of curvature) and the physical properties of the inert gas (argon), requires experimental calibration, and is typically taken as 150-2ΔP. 基础 Minimum safe air pressure difference (fixed value): The basic pressure difference that must be maintained even when the flow rate is 0 to prevent outside air from infiltrating. It is usually set to 1-2 Pa in the process.

[0045] Application example: When the flow velocity V = 0.2 m / s (too high), take K = 180, ΔP 基础 =1Pa, ΔP 目标 =180×(0.2)²+1=180×0.04+1=7.2+1=8.2Pa (In actual processes, it will be rounded to 8Pa, that is, if the upstream pressure is 25Pa, the downstream pressure needs to be adjusted to 33Pa).

[0046] When the flow velocity V = 0.1 m / s (too low), and K = 180, ΔP 基础 =1Pa, ΔP 目标 =180×(0.1)²+1=180×0.01+1=1.8+1=2.8Pa (actually rounded to 3Pa, that is, when the upstream is 25Pa, the downstream is adjusted to 28Pa).

[0047] ΔP calculated by the basic model 目标 It will be adjusted through two correction modules to avoid deviations caused by environmental or process fluctuations.

[0048] 1. Pressure distribution correction: Combining the weighted average of the pressure sensors in each chamber (i.e., P mentioned above) 腔室 =0.6×`P 核心区 +0.3×`P 过渡区 +0.1×`P 边缘区 If the core pressure is 5% lower than the average, then at ΔP 目标 An additional 0.5-1 Pa is added to ensure the positive pressure on the surface of the melt.

[0049] 2. Flow velocity fluctuation correction: By using "sliding window filtering" (such as taking the average flow velocity over the past 5 seconds), if the instantaneous flow velocity deviates from the average value by more than 0.02 m / s (such as a sudden increase from 0.18 m / s to 0.2 m / s), the ΔP target will be temporarily increased by 10% to cope with the local negative pressure that may be caused by short-term fluctuations.

[0050] The algorithm incorporates a built-in safety threshold to prevent damage to equipment or compromise of protection due to excessively high / low pressure differences caused by sensor malfunctions or extreme conditions. Upper limit boundary: ΔP目标 The maximum pressure should not exceed 10 Pa. Even if the flow rate is close to 0.2 m / s and the corrected value exceeds 10 Pa, 10 Pa will be the upper limit to avoid excessive pressure in the downstream chamber, which could lead to leakage at the sealing flow channel interface or waste of inert gas. Lower limit boundary: ΔP 目标 The minimum pressure should not be lower than 2 Pa. Even if the flow velocity is close to 0.1 m / s and the corrected value is lower than 2 Pa, 2 Pa should still be used as the lower limit to ensure that at least a basic positive pressure gradient is maintained to prevent outside air from seeping in. If the flow velocity exceeds 0.25 m / s for 10 seconds (far exceeding the process range), or ΔP 目标 If the calculated value exceeds 15Pa (extreme anomaly), the algorithm will trigger an alarm and suspend intake regulation, while prompting manual inspection of the flow channel (e.g., whether it is blocked).

[0051] Furthermore, in principle, to maintain melt flow, the pressure difference ΔP between adjacent chambers must satisfy: ΔP < ρgΔh, where ρ is the density of the aluminum alloy melt, g is the acceleration due to gravity, and Δh is the difference in melt level between adjacent chambers. This is mainly based on the following fluid dynamics principle: According to Bernoulli's equation, for any two adjacent chambers, applying Bernoulli's equation and neglecting surface velocity and frictional losses, we can obtain: v = Where v is the melt velocity in the flow channel, g is the acceleration due to gravity, Δh is the difference in melt level between adjacent chambers, ΔP is the pressure difference between adjacent chambers, and ρ is the density of the aluminum alloy melt. The pressure difference is a "reverse constraint term" for the flow velocity: in the formula... It is the "weakening term" of the pressure difference on the flow velocity—the larger the pressure difference, the lower the velocity Δh. The smaller the value of V, the lower the flow velocity V; conversely, the smaller the pressure difference, the closer the flow velocity is to the "theoretical maximum flow velocity" determined solely by the liquid level difference Δh. To ensure smooth melt flow, Δh > ΔP / (ρg) must be satisfied, i.e., ΔP < ρgΔh.

[0052] Example of pressure difference calculation with a flow velocity V of 0.2 m / s (taking a melting furnace → holding furnace as an example). Given parameters: V = 0.2 m / s, Δh = 0.2 m (actual liquid level difference), ρ = 268 m / s 2 Substitute the parameters into the formula to deduce the maximum allowable differential pressure value ΔP. max : 0.2= Finally, we arrive at: ΔP max ≈0.19796×25480≈5050Pa. This indicates that at a flow rate of 0.2 m / s, the maximum allowable pressure difference between adjacent chambers is approximately 5050 Pa, while the pressure difference set in the scheme is much smaller than this upper limit—the pressure difference has almost no obstruction to the 0.2 m / s flow rate and only plays a protective role in “building a pressure ladder”.

[0053] In summary, the above system and method can form a continuous "protective channel" during the smelting and casting process of 7065 aluminum alloy, keeping the melt surrounded by an inert atmosphere, fundamentally isolating the air from contact with the melt, effectively inhibiting oxidation reactions, and reducing the generation of oxide film defects.

[0054] The orientations mentioned in this specification are based on the orientation of the multi-chamber synergistic positive pressure protection system and oxidation inhibition control method for 7065 aluminum alloy melting and casting during normal operation. They do not limit the orientation during storage and transportation, but only represent relative positional relationships, not absolute positional relationships.

[0055] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A multi-chambered synergistic positive pressure protection system for 7065 aluminum alloy smelted casting, characterized in that: The system comprises a melting furnace, a holding furnace and an on-line degassing device arranged in sequence, and is connected by a sealed flow channel between adjacent chambers to form a relatively closed system. The melting furnace, the holding furnace and the on-line degassing device are respectively provided with independent inert gas closed-loop control systems, and the inert gas closed-loop control systems independently supply gas to each chamber and detect the pressure value of the chamber.

2. The multi-chamber coordinated positive pressure protection system for melting and casting of 7065 aluminum alloy according to claim 1, characterized in that: The sealed flow channel is provided with a flow rate monitoring device, and the flow rate monitoring device is electrically connected with the inert gas closed-loop control system and can dynamically adjust the air intake according to the monitored melt flow rate.

3. A multi-chambered synergistic positive pressure protection system for smelting and casting of 7065 aluminum alloy as claimed in claim 1, wherein: The inert gas closed-loop control system comprises a gas inlet system and a pressure detection system, the pressure detection system comprises a plurality of pressure sensors installed in the corresponding chambers, and the pressure sensors are arranged at different positions in each chamber.

4. A multi-chambered synergistic positive pressure protection system for smelting and casting of 7065 aluminum alloy as claimed in claim 1, wherein: The sealed flow channel is provided with a pressure gauge at each of the front end and the rear end.

5. A multi-chambered synergistic positive pressure protection system for 7065 aluminum alloy smelting and casting as claimed in claim 1, wherein: The sealed flow channel is of equal cross section, and a large-curvature-radius elbow pipe is used at the turning part of the sealed flow channel, and the curvature radius is greater than five times the diameter of the sealed flow channel.

6. A control method for oxidation inhibition using the multi-chamber synergic positive pressure protection system according to any one of claims 1-5, characterized in that: The method comprises the following steps: S1, melting process: melting 7065 aluminum alloy raw materials in a melting furnace, introducing inert gas into the hearth of the melting furnace, and maintaining the pressure in the melting furnace at a micro-positive pressure state by the inert gas closed-loop control system; S2, holding process: transferring the melted aluminum alloy melt to a holding furnace through a sealed flow channel, introducing inert gas into the sealed hearth of the holding furnace, maintaining the pressure in the holding furnace at a micro-positive pressure state by the inert gas closed-loop control system, and the pressure in the holding furnace is not less than the pressure of the melting furnace in step S1; S3, refining process: introducing the holding aluminum alloy melt into the sealed reaction chamber of the on-line degassing device through the sealed flow channel, continuously introducing inert gas into the top space of the reaction chamber in addition to blowing refining gas into the melt through the rotating nozzle, maintaining the internal pressure of the on-line degassing device at a positive pressure state, and the internal pressure of the on-line degassing device is not less than the pressure of the holding furnace in S2; S4, casting process: casting the aluminum alloy melt refined by the on-line degassing device into an ingot; The melting furnace, the holding furnace and the on-line degassing device are connected in sequence by the sealed flow channel to form a relatively closed system, and the chamber pressures along the melt flow direction present a stepwise increase or balanced distribution.

7. The control method for oxidation inhibition with a multi-chamber coordinated positive pressure protection system according to claim 6, characterized in that: The chamber pressures of the melting furnace, the holding furnace and the on-line degassing device along the melt flow direction present a stepwise increase.

8. The control method for oxidation inhibition using a multi-chamber coordinated positive pressure protection system according to claim 7, characterized in that: The pressure range in the melting furnace is 0.1 Pa-30 Pa; the pressure range in the holding furnace is 1 Pa-35 Pa; and the pressure range in the on-line degassing device is 2 Pa-45 Pa. The pressure difference between adjacent chambers needs to satisfy: ΔP 目标 = K × V² + ΔP 基础 ; wherein, ΔP 目标 is the target air pressure difference required by adjacent chambers; V: the melt flow rate detected by the flow rate monitoring device in real time; K: flow rate coefficient; ΔP 基础 : minimum safe air pressure difference.

9. The control method for oxidation inhibition using a multi-chamber coordinated positive pressure protection system according to claim 7, characterized in that: The inert gas is argon with a purity of not less than 99.99%.

10. The control method for oxidation inhibition with a multi-chamber coordinated positive pressure protection system according to claim 7, characterized in that: The flow speed of the aluminum alloy melt in the sealed flow channel is controlled at 0.1 m / s-0.2 m / s.

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