A method for preparing a large-size flat cast ingot of superhard Al-Zn-Mg-Cu aluminum alloy

Abstract

The application relates to a preparation method of a superhard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot, and particularly relates to a preparation method of a superhard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot. The application aims at solving the problem that cracks and waste products are easily generated in the production of the Al-Zn-Mg-Cu aluminum alloy flat ingot by using the existing traditional casting tool. The method comprises the following steps: S1, preparing a double-drainage cooling graphite crystallizer; S2, weighing; S3, smelting; and S4, casting. The graphite crystallizer is adopted in the application, and the scientific proportioning of raw materials and the reasonable adjustment of process parameters are combined to reduce the generation of ingot crack defects, so that the forming rate of the ingot reaches more than 93%.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of a super-hard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot. BACKGROUND

[0002] In today's era of rapid development of science and technology, aluminum alloy has been widely used in many fields such as aerospace and transportation due to its low density, high strength, good corrosion resistance and excellent processing performance. In the production process of aluminum alloy, casting process is one of the key links, which directly determines the quality and performance of the aluminum alloy ingot, and then affects the subsequent processing and use.

[0003] The traditional DC casting (direct water cooling semi-continuous casting) method exposes a series of serious problems when casting Al-Zn-Mg-Cu aluminum alloy flat ingot with small solid-liquid zone. First, at the beginning of casting, the bottom of the ingot often appears warping phenomenon, and the warping degree is large. This warping phenomenon will lead to uneven stress distribution in the ingot, and when the stress exceeds the ultimate strength of the material, it is easy to cause cracking and crack. These cracks not only destroy the integrity of the ingot, but also may further expand in the subsequent processing process, seriously reducing the quality and reliability of the aluminum alloy product, and even causing the product to be scrapped.

[0004] Secondly, during the whole casting process, the lubrication effect of lubricating oil has a crucial influence on the quality of the ingot. Because in the traditional casting process, the lubrication of the lubricating oil is difficult to be uniform, which makes the friction force received by the ingot during solidification and drawing uneven. Local excessive friction will hinder the normal shrinkage and movement of the ingot, thus producing additional stress concentration in the ingot, and finally leading to the cracking of the ingot. These cracking and cracking problems caused by the bottom warping and uneven lubrication make the yield of the ingot always at a low level, greatly increasing the production cost, limiting the production efficiency and market competitiveness of the aluminum alloy product.

[0005] With the rapid development of aerospace, transportation and other industries, the demand for high-quality aluminum alloy ingot is increasing, and these defects of the traditional casting process are more and more prominent, which cannot meet the requirements of the industry for high-quality and high-yield aluminum alloy ingot. Therefore, it is urgent to develop a new casting technology and equipment to solve these problems. SUMMARY

[0006] The present application is to solve the problem that the existing traditional casting tool produces cracked waste products when producing Al-Zn-Mg-Cu aluminum alloy flat ingot, and provides a preparation method of a super-hard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot.

[0007] A kind of preparation method of superhard Al-Zn-Mg-Cu aluminum alloy large specification flat cast ingot is completed according to the following steps:

[0008] I, weighing: according to the mass percentage Si less than 0.5%, Fe less than 1.0%, Cu: 1.8%~3.0%, Mn less than 0.5%, Mg: 1.8%~3.0%, Cr less than 0.3%, Ni less than 0.3%, Zn: 5.0%~8.2%, Zr: 0.05%~0.5%, Ti: 0.02%~0.2% and the balance is Al, take aluminum ingot, pure Cu plate, pure Mg ingot, pure Zn ingot, Al-Zr intermediate alloy and Al-Ti intermediate alloy as smelting raw materials;

[0009] II, smelting: the weighed aluminum ingot, pure Cu plate, pure Zn ingot and Al-Zr intermediate alloy are added to the natural gas melting furnace, pure Mg ingot and Al-Ti intermediate alloy are added when the temperature is 700~720 ℃, electromagnetic stirring is used for 25~35 min when the temperature reaches 720 ℃, sampling analysis chemical composition, after the chemical composition is qualified, the aluminum alloy melt is obtained;

[0010] III, casting: the aluminum alloy melt is introduced into the holding furnace, Ar gas refining is carried out for 30~40 min when the temperature is 720~780 ℃, then the melt is obtained by standing for 30~40 min at the temperature of 720~780 ℃, then the melt is first flowed into the online degassing device, Ar gas is introduced into the online degassing device, the purity of Ar gas is required to be 99.996% and above, the working pressure of argon pipeline is 0.3MPa~1.0MPa;Then flow into the filtering device, then the melt is injected into the double-row water-cooled graphite crystallizer under the conditions of casting speed of 40~55 mm / min, casting temperature of 685~710 ℃, cooling water flow of 75~145T / h, cooling water temperature of 15~28 ℃ and online seeding of Al-Ti-B wire to produce superhard Al-Zn-Mg-Cu aluminum alloy large specification flat cast ingot.

[0011] The present application has the following advantages:

[0012] The present application adopts the double-row cooling water impact area located in the area where the conductivity of the surface of the cast ingot is minimum and the temperature has a rebound, which ensures the cooling effect of the cast ingot, and eliminates the splashing of the cooling water, avoiding the generation of interference fountain;The design of the graphite plate inlaid in the inner cavity of the crystallizer does not need lubricating oil for production casting due to the self-lubricating property of graphite, which not only improves the surface quality, but also avoids the pollution to water quality, and saves the production cost. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is the structure diagram of double-row water-cooled graphite crystallizer;

[0014] Figure 2It is a structure exploded schematic view of double water-cooling graphite crystallizer;

[0015] Figure 3 It is a local enlarged view of double water-cooling graphite crystallizer;

[0016] Figure 4 It is a structure schematic view of water inlet filter screen;

[0017] Figure 5 It is a structure schematic view of air-operated control valve. DETAILED DESCRIPTION

[0018] The technical scheme of the present application is not limited to the following listed specific embodiments, and also includes any combination between the specific embodiments.

[0019] Specific embodiment one: the preparation method of the superhard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot in the embodiment is completed according to the following steps:

[0020] I. Weighing: according to the proportion of Si less than 0.5%, Fe less than 1.0%, Cu: 1.8% to 3.0%, Mn less than 0.5%, Mg: 1.8% to 3.0%, Cr less than 0.3%, Ni less than 0.3%, Zn: 5.0% to 8.2%, Zr: 0.05% to 0.5%, Ti: 0.02% to 0.2%, and the balance of Al, weigh the aluminum ingot, pure Cu plate, pure Mg ingot, pure Zn ingot, Al-Zr intermediate alloy and Al-Ti intermediate alloy as the smelting raw materials;

[0021] II. Smelting: the weighed aluminum ingot, pure Cu plate, pure Zn ingot and Al-Zr intermediate alloy are added to the natural gas melting furnace, the pure Mg ingot and Al-Ti intermediate alloy are added at a temperature of 700 to 720 ℃, the electromagnetic stirring is used for 25 to 35 min when the temperature reaches 720 ℃, the chemical composition is analyzed by sampling, and the aluminum alloy melt is obtained after the chemical composition is qualified;

[0022] III. Casting: the aluminum alloy melt is introduced into the holding furnace, Ar gas refining is carried out for 30 to 40 min at a temperature of 720 to 780 ℃, then the melt is obtained by standing for 30 to 40 min at a temperature of 720 to 780 ℃, then the melt is first flowed into the online degassing device, Ar gas is introduced into the online degassing device, the purity of the Ar gas is required to be 99.996% or above, and the working pressure of the argon gas pipeline is 0.3 MPa to 1.0 MPa; then the melt is flowed into the filtering device, and then the melt is injected into the double water-cooling graphite crystallizer under the conditions of a casting speed of 40 to 55 mm / min, a casting temperature of 685 to 710 ℃, a cooling water flow of 75 to 145 T / h, a cooling water temperature of 15 to 28 ℃ and online seeding of Al-Ti-B wire to prepare the superhard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot.

[0023] Specific embodiment two: the difference between this embodiment and specific embodiment one is that the double-row water-cooled graphite crystallizer is composed of a large-face box body 8, a small-face box body 4, a large-face lower pressing cover 1, a small-face lower pressing cover 3, a large-face upper pressing cover 9 and a small-face upper pressing cover 6; the large-face box body 8, the large-face lower pressing cover 1 and the large-face upper pressing cover 9 form a large-face assembly, and the small-face box body 4, the small-face lower pressing cover 3 and the small-face upper pressing cover 6 form a small-face assembly; two large-face assemblies and two small-face assemblies enclose the inner cavity of the crystallizer. The rest is the same as specific embodiment one.

[0024] The double-row water-cooled graphite crystallizer is cooled by heat conduction through the surface of the graphite plate in one time, and the cavity of the crystallizer is made of 2A50 aluminum alloy by forging and manufacturing by a numerical control machining center.

[0025] In this embodiment, the inner cavity size of the crystallizer is determined by the shrinkage coefficient of aluminum alloy, the measurement of the cross-sectional size of ingots of different specifications of the same alloy, and the selection of appropriate tool materials according to the characteristics of the crystallizer. According to the characteristics of aluminum alloy and some product defects that have occurred on site, the crystallizer is designed as an inner oblong circular casting tool with a certain inclination. The inner cavity of the hard aluminum alloy crystallizer is a combined box body composed of two large-face box bodies and two small-face box bodies, which are connected and combined and fixed by bolts. The crystallizer is designed with double rows of drainage holes. The first row of drainage holes is designed to be 3.8 mm in size, and the angle is 44° with the vertical direction. The second row of drainage holes is designed to be 3.2 mm in size, and the angle is 26° with the vertical direction. The size can be freely switched according to the hard aluminum alloy casting process through the pneumatic control valve. In the design process of the hard alloy double-row water-cooled graphite crystallizer, the upper flow heat conduction area of the ingot is moved upward, and the width of the stagnation area of the ingot cooling is increased by designing the cooling water holes, thereby avoiding surface defects, cracks, and aluminum liquid leakage during the process. In the design process of the graphite crystallizer, the graphite plate is embedded in the inner cavity of the crystallizer, which effectively reduces the casting friction, improves the surface quality, reduces the surface segregation, and reduces the milling surface geometry waste. Match the process parameters, and use the single-row and double-row alternating cooling method at the beginning to reduce the crack tendency at the beginning of casting and improve the ingot forming rate.

[0026] Specific embodiment three: the difference between this embodiment and specific embodiment two is that the small-face box body 4 and the large-face box body 8 are both machined with a groove for embedding the graphite plate, and the graphite plate is tightly fixed in the box body by the small-face upper pressing cover 6 and the large-face upper pressing cover 9. After the small-face assembly of the crystallizer, the elongated parts on both sides of the small-face upper pressing cover 6 are lapped on the large-face assembly, and the part of the large-face upper pressing cover 9 lapped with the small-face assembly is machined with threads for locking and fixing the small-face assembly and the large-face assembly, and the surface of the graphite plate serves as the crystallization working surface. The rest is the same as specific embodiment two.

[0027] The effect of the large and small surface inlaid high-purity graphite plate in this embodiment is to increase the lubrication of the ingot and the inside of the crystallizer during casting, reduce the tendency of the ingot to crack, and improve the ingot forming rate.

[0028] Specific embodiment four: the difference between this embodiment and specific embodiment two is that the inclination angle of the working surface of the graphite plate inner cavity in the small surface assembly and the large surface assembly is 0.68°. The rest is the same as specific embodiment two.

[0029] Specific embodiment five: the difference between this embodiment and specific embodiment two is that the large surface box 8 and the small surface box 4 are processed with a partition structure on the inside up and down to form an upper cavity and a lower cavity as a water chamber for cooling water; the air-actuated control valve 5 is located inside the lower cavity, the water inlet quick connector 2 is installed in the lower cavity, and the interface part is exposed outside the cavity and connected with the external water supply pipeline; the water inlet filter screen 7 is tightly installed on the water inlet quick connector 2 and penetrates the upper and lower cavities, and the water inlet filter screen 7 and the lower cavity are water-tightly isolated; the upper cavity is provided with a lower drain hole with a diameter of Φ3.2mm and an angle of 26° with the vertical direction, and the lower drain hole is in communication with the internal space of the upper cavity and can drain water in the upper cavity into the inner cavity of the crystallizer; the lower cavity is provided with an upper drain hole with a diameter of Φ3.8mm and an angle of 44° with the vertical direction, and the upper drain hole is in communication with the internal space of the lower cavity and can drain water in the lower cavity into the inner cavity of the crystallizer. The rest is the same as specific embodiment two.

[0030] The air-actuated control valve controls the water flow channel between the lower cavity and the upper cavity. When it is in the closed state, it prevents water flow in the upper cavity from entering the lower cavity. When it is opened, it allows water flow to flow from the specific gap from the upper cavity to the lower cavity, thereby achieving precise regulation of the water flow path.

[0031] The through design makes the water first pass through the water inlet filter screen for filtering treatment after entering the box through the water inlet quick connector, so as to remove impurity particles in the water and prevent them from causing blockage or damage to the internal structure of the box and the subsequent water flow channel. The water inlet filter screen and the water inlet quick connector are connected in a sealed manner, such as using a rubber sealing ring or other sealing elements, to ensure that the water flow can only enter the box through the filter screen and cannot leak from the connection between the connector and the filter screen or bypass the filter screen to directly enter the box.

[0032] Specific embodiment six: the difference between this embodiment and specific embodiment two is that the large surface upper gland 9, the large surface lower gland 1, the small surface upper gland 6, and the small surface lower gland 3 are processed with an annular groove near the inside of the water chamber, and an "O" type sealing silica gel strip is installed in the groove. The rest is the same as specific embodiment two.

[0033] The double ring type "O" type sealing silica gel strip used in the embodiment prevents the cooling water in the cavity from leaking after the mold box is assembled.

[0034] Specific embodiment seven: the difference between this embodiment and specific embodiments two and five is that the large face box 8, the small face box 4, the water inlet filter screen 7, the water inlet quick connector 2, the air control valve 5, the large face lower pressing cover 1, the small face lower pressing cover 3, the large face upper pressing cover 9 and the small face upper pressing cover 6 are connected by adjusting the screw rod and the nut. The others are the same as specific embodiments two and five.

[0035] Specific embodiment eight: the difference between this embodiment and specific embodiment one is that the Zr content in the Al-Zr intermediate alloy is 5%, and the Ti content in the Al-Ti intermediate alloy is 5%. The others are the same as specific embodiment one.

[0036] Specific embodiment nine: the difference between this embodiment and specific embodiment one is that the filter device uses double-stage ceramic filter sheets for filtering, and the double-stage ceramic filter sheets are imported 30 ppi+60 ppi. The others are the same as specific embodiment one.

[0037] Specific embodiment ten: the difference between this embodiment and specific embodiment one is that the cooling water is first cooled by single-row pulse water at 75-80 m 3 / h, and when the casting length is 150 mm, the cooling water is cooled by double-row water at 80-100 m 3 / h, when the casting length is 500 mm, the cooling water is cooled by double-row water at 90-120 m 3 / h, and after 800 mm, the cooling water is cooled by single-row water at 130-145 m 3 / h. The others are the same as specific embodiment one.

[0038] Specific embodiment eleven: the difference between this embodiment and specific embodiment one is that the cross-sectional size of the super-hard Al-Zn-Mg-Cu aluminum alloy large-size flat cast ingot is 520x1680 mm. The others are the same as specific embodiment one.

[0039] The beneficial effects of the present application are verified by the following examples:

[0040] Example one: a preparation method of a super-hard Al-Zn-Mg-Cu aluminum alloy large-size flat cast ingot is completed according to the following steps:

[0041] I. Weighing: according to the mass fraction of Si less than 0.5%, Fe less than 1.0%, Cu: 2.5%, Mn less than 0.5%, Mg: 2.6%, Cr less than 0.3%, Ni less than 0.3%, Zn: 6.2%, Zr: 0.2%, Ti: 0.026%, and the balance of Al, weigh the aluminum ingot, pure Cu plate, pure Mg ingot, pure Zn ingot, Al-Zr intermediate alloy and Al-Ti intermediate alloy as smelting raw materials;

[0042] II. Smelting: add the weighed aluminum ingot, pure Cu plate, pure Zn ingot and Al-Zr intermediate alloy into the natural gas melting furnace, add pure Mg ingot and Al-Ti intermediate alloy when the temperature is 700℃, use electromagnetic stirring for 30min when the temperature reaches 720℃, sample and analyze the chemical composition, and the aluminum alloy melt is obtained after the chemical composition is qualified;

[0043] III. Casting: introduce the aluminum alloy melt into the holding furnace, refine for 30min at a temperature of 740℃ under Ar gas, then stand for 60min at a temperature of 735℃ to obtain a casting melt, then flow into the online degassing device, introduce Ar gas into the online degassing device, the purity of Ar gas is required to be 99.996% or more, and the working pressure of the argon pipeline is 0.3MPa-1.0MPa; then flow into the filtering device, and then pass through the flow disc to cool at a casting speed of 50mm / min, a casting temperature of 705℃, and cooling water flow first at 80m 3 / h with single row water, to a casting length of 150mm, cooling water at 90m 3 / h with double row water cooling, to a casting length of 500mm, cooling water at 90m 3 / h-120m 3 / h cooling, cooling water at 130m 3 / h-145m 3 / h cooling, the cooling water temperature is 23℃, and the melt is injected into a double row water cooling graphite crystallizer under the condition of online seeding of Al-Ti-B wire to produce super-hard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot.

[0044] The double row water cooling graphite crystallizer is composed of a large face box body 8, a small face box body 4, a large face lower pressing cover 1, a small face lower pressing cover 3, a large face upper pressing cover 9 and a small face upper pressing cover 6; the large face box body 8, the large face lower pressing cover 1 and the large face upper pressing cover 9 form a large face assembly, the small face box body 4, the small face lower pressing cover 3 and the small face upper pressing cover 6 form a small face assembly; two large face assemblies and two small face assemblies enclose the inner cavity of the crystallizer;

[0045] The inner side of the small-face box 4 and the large-face box 8 is processed with a groove inlaid with a graphite plate, which is fixed by the small-face upper gland 6 and the large-face upper gland 9; after the small-face assembly is assembled, the elongated parts on both sides of the small-face upper gland 6 are overlapped on the large-face assembly, the part on the large-face upper gland 9 which is overlapped with the small-face assembly is processed with a thread, which is used for locking and fixing the small-face assembly and the large-face assembly, and the surface of the graphite plate is used as a crystallization working surface;

[0046] The inclination angle of the working surface of the graphite plate in the small-face assembly and the large-face assembly is 0.68°;

[0047] The large-face box 8 and the small-face box 4 are processed with a partition structure on the inside thereof, forming an upper cavity and a lower cavity as a water chamber for cooling water; the air control valve 5 is located in the lower cavity, the water inlet quick connector 2 is installed in the lower cavity, and the interface part thereof is exposed outside the cavity and connected with an external water supply pipeline; the water inlet filter screen 7 is tightly installed on the water inlet quick connector 2 and penetrates the upper and lower cavities, and the water inlet filter screen 7 and the lower cavity are water-tightly isolated; the upper cavity is provided with a lower water outlet hole, the diameter of the lower water outlet hole is Φ3.2mm, the angle is 26° with the vertical direction, the lower water outlet hole is communicated with the internal space of the upper cavity, and the water in the upper cavity can be discharged into the inner cavity of the crystallizer; the lower cavity is provided with an upper water outlet hole, the diameter of the upper water outlet hole is Φ3.8mm, the angle is 44° with the vertical direction, the upper water outlet hole is communicated with the internal space of the lower cavity, and the water in the lower cavity can be discharged into the inner cavity of the crystallizer; the large-face upper gland 9, the large-face lower gland 1, the small-face upper gland 6 and the small-face lower gland 3 are processed with an annular groove near the inner side of the water chamber, and an “O”-shaped sealing silica gel strip is installed in the groove; the large-face box 8, the small-face box 4, the water inlet filter screen 7, the water inlet quick connector 2, the air control valve 5, the large-face lower gland 1, the small-face lower gland 3, the large-face upper gland 9 and the small-face upper gland 6 are tightly connected by adjusting the screw rod and the nut;

[0048] The Zr content in the Al-Zr intermediate alloy is 5%, and the Ti content in the Al-Ti intermediate alloy is 5%; the filter device adopts double-stage ceramic filter sheets, and the double-stage ceramic filter sheets are imported 30ppi+60ppi; the cross-sectional size of the super-hard Al-Zn-Mg-Cu aluminum alloy large-size flat cast ingot is 520×1680mm.

[0049] The chemical composition of the super-hard Al-Zn-Mg-Cu aluminum alloy 520×1680mm flat cast ingot obtained in the embodiment is qualified, the surface is free of cracks, slag inclusions and other defects, and the forming rate reaches 100%.

Claims

1. A method for producing a superhard Al-Zn-Mg-Cu aluminium alloy large-size slab, characterized in that The preparation method of the superhard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot is completed according to the following steps: I. Weighing: according to the mass percentage of Si less than 0.5%, Fe less than 1.0%, Cu: 1.8% to 3.0%, Mn less than 0.5%, Mg: 1.8% to 3.0%, Cr less than 0.3%, Ni less than 0.3%, Zn: 5.0% to 8.2%, Zr: 0.05% to 0.5%, Ti: 0.02% to 0.2%, and the balance of Al, weigh the aluminum ingot, pure Cu plate, pure Mg ingot, pure Zn ingot, Al-Zr intermediate alloy and Al-Ti intermediate alloy as the smelting raw materials; II. Smelting: the weighed aluminum ingot, pure Cu plate, pure Zn ingot and Al-Zr intermediate alloy are added to the natural gas melting furnace, the pure Mg ingot and Al-Ti intermediate alloy are added at a temperature of 700 to 720℃, the temperature reaches 720℃, and the electromagnetic stirring is used for 25 to 35 minutes, the chemical composition is analyzed by sampling, and the aluminum alloy molten liquid is obtained after the chemical composition is qualified; III. Casting: the aluminum alloy molten liquid is introduced into the holding furnace, the Ar gas refining is carried out at a temperature of 720 to 780℃ for 30 to 40 minutes, then the molten liquid is obtained by standing at a temperature of 720 to 780℃ for 30 to 40 minutes, then the molten liquid is first flowed into the online degassing device, Ar gas is introduced into the online degassing device, the purity of the Ar gas is required to be 99.996% or above, and the working pressure of the argon gas pipeline is 0.3MPa to 1.0MPa; then the molten liquid is flowed into the filtering device, and then the molten liquid is injected into the double water-cooled graphite crystallizer under the conditions of a casting speed of 40 to 55mm / min, a casting temperature of 685 to 710℃, a cooling water flow of 75 to 145T / h, a cooling water temperature of 15 to 28℃, and online seeding of Al-Ti-B wire to prepare the superhard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot. The double-row water-cooling graphite crystallizer is composed of a large-face box body (8), a small-face box body (4), a large-face lower pressing cover (1), a small-face lower pressing cover (3), a large-face upper pressing cover (9) and a small-face upper pressing cover (6); the large-face box body (8), the large-face lower pressing cover (1) and the large-face upper pressing cover (9) form a large-face assembly, and the small-face box body (4), the small-face lower pressing cover (3) and the small-face upper pressing cover (6) form a small-face assembly; two large-face assemblies and two small-face assemblies enclose an inner cavity of the crystallizer; the small-face box body (4) and the large-face box body (8) are both internally provided with grooves for embedding graphite plates, and the graphite plates are fixedly pressed in the box bodies by the small-face upper pressing cover (6) and the large-face upper pressing cover (9); after the small-face assembly is assembled, the elongated portions on both sides of the small-face upper pressing cover (6) are overlapped on the large-face assembly, and the portion of the large-face upper pressing cover (9) that is overlapped with the small-face assembly is provided with threads for locking and fixing the small-face assembly and the large-face assembly, and the surface of the graphite plate serves as a crystallization working surface; the large-face box body (8) and the small-face box body (4) are provided with partition structures formed by processing upper and lower portions of the internal portions thereof, thereby forming an upper cavity and a lower cavity as water chambers for cooling water; an air-actuated control valve (5) is located in the lower cavity, and a water inlet quick connector (2) is installed in the lower cavity, with the interface portion thereof exposed outside the cavity and connected with an external water supply pipeline; a water inlet filter screen (7) is tightly installed on the water inlet quick connector (2) and penetrates the upper and lower cavities, and the water inlet filter screen (7) is in watertight isolation with the lower cavity; the upper cavity is provided with a lower water outlet hole with a diameter of Φ3.2 mm and an angle of 26° with the vertical direction, and the lower water outlet hole is in communication with the internal space of the upper cavity and can discharge water in the upper cavity into the inner cavity of the crystallizer; the lower cavity is provided with an upper water outlet hole with a diameter of Φ3.8 mm and an angle of 44° with the vertical direction, and the upper water outlet hole is in communication with the internal space of the lower cavity and can discharge water in the lower cavity into the inner cavity of the crystallizer.

2. A method of producing a superhard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot according to claim 1, characterized in that The inclination angle of the working surface of the graphite plate in the inner cavity of the small-face assembly and the large-face assembly is 0.68°.

3. The method of producing a superhard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot according to claim 1, characterized in that The large-face upper pressing cover (9), the large-face lower pressing cover (1), the small-face upper pressing cover (6) and the small-face lower pressing cover (3) are provided with annular grooves near the inner sides of the water chambers, and "O" type sealing silica gel strips are installed in the grooves.

4. The method of producing a superhard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot according to claim 1, characterized in that The large-face box body (8), the small-face box body (4), the water inlet filter screen (7), the water inlet quick connector (2), the air-actuated control valve (5), the large-face lower pressing cover (1), the small-face lower pressing cover (3), the large-face upper pressing cover (9) and the small-face upper pressing cover (6) are tightly connected by adjusting screws and nuts.

5. The method of producing a superhard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot according to claim 1, characterized in that The Zr content in the Al-Zr intermediate alloy is 5%, and the Ti content in the Al-Ti intermediate alloy is 5%.

6. The method of producing a superhard Al-Zn-Mg-Cu aluminum alloy large-size flat ingot according to claim 1, characterized in that The filter device adopts double-stage ceramic filter sheets for filtering, and the double-stage ceramic filter sheets are imported 30 ppi+60 ppi.

7. The method for preparing a large-size flat ingot of ultra-hard Al-Zn-Mg-Cu aluminum alloy according to claim 1, characterized in that... The cooling water first cools at a single row of 75-80 m 3 / h, to a casting length of 150 mm. The cooling water cools at a double row of 80-100 m 3 / h, to a casting length of 500 mm. The cooling water cools at a double row of 90-120 m 3 / h, to a casting length of 800 mm. The cooling water cools at a single row of 130-145 m 3 / h, to a casting length of 1000 mm.

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