A continuous casting process for an aluminum alloy

Abstract

The application discloses a continuous casting and rolling process of an aluminum alloy. The continuous casting and rolling process of the aluminum alloy comprises the following steps: after high-temperature molten aluminum is degassed and filtered, the molten aluminum is sent into a roll gap through a feeding nozzle to be cast and rolled; inert gas is used to blow and clean between the feeding nozzle and the roll gap to form a cyclone protection area to cover and protect the molten aluminum. The continuous casting and rolling process of the aluminum alloy has the advantages that: the shape of the feeding nozzle is designed, and when the inert gas is used to blow and clean, a cyclone protection area is formed between the outer layer of the feeding nozzle and the roll, so that the inert gas in normal temperature state cannot directly blow to the surface of the high-temperature molten aluminum to generate liquid surface fluctuation and surface ripples, and the molten aluminum is prevented from being cooled and solidified to form a crust; in addition, the inert gas cyclone protection area plays a covering protection role and does not generate an oxidation film, so that the cast and rolled aluminum plate does not have an oxidation film pressing defect.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy technology, and specifically relates to a continuous casting and rolling process for aluminum alloys. Background Technology

[0002] Continuous casting and rolling of aluminum alloys is a production process in which molten aluminum is continuously fed into the gap between two relatively rotating and water-cooled rolls, and then cooled, cast, and continuously rolled out as aluminum alloy sheet / coil blanks.

[0003] In actual production, molten aluminum is fed into the roll gap through a feeding nozzle (usually called a casting nozzle), and there is a gap of 0.5-1.0 mm between the casting nozzle and the roll, so they do not directly contact each other. At the initial contact point between the molten aluminum and the roll, due to the gap between the casting nozzle and the roll, the high-temperature molten aluminum will be exposed to the air and form an oxide film. This oxide film will then enter the roll gap and be rolled onto the surface of the aluminum sheet / coil, forming an oxide film indentation defect that affects subsequent processing.

[0004] Currently, the industry employs methods such as increasing the strength of the casting nozzle or improving its material to reduce nozzle deformation and prevent the nozzle from contacting the rolls, thus avoiding surface streaks on the aluminum sheet. Simultaneously, methods like minimizing the gap between the nozzle and the rolls, or adding graphite sheets to the nozzle, are used to reduce oxide film formation and indentation. However, none of these methods completely solve the quality defect of oxide film indentation in continuous aluminum alloy casting and rolling. Furthermore, reducing the gap between the nozzle and the rolls allows the high-temperature molten aluminum to enter the nozzle, causing it to deform due to heat, making it difficult to ensure a gap between the nozzle and the rolls and preventing contact, which easily leads to streaks on the roll surface.

[0005] In view of this, the present invention proposes a new continuous casting and rolling process for aluminum alloys, which can eliminate surface streaks and oxide film indentation in continuous casting and rolling of aluminum alloys. Summary of the Invention

[0006] The purpose of this invention is to provide a continuous casting and rolling process for aluminum alloys. By designing the shape of the feed nozzle, an inert gas purging process is used to form a cyclone protection zone between the outer layer of the feed nozzle and the roll. This prevents the inert gas at room temperature from directly blowing onto the surface of the high-temperature molten aluminum, causing the molten aluminum to cool down and solidify into a shell. At the same time, the inert gas cyclone protection zone plays a covering and protective role, preventing the formation of an oxide film. This ensures that the cast and rolled aluminum plate does not have oxide film indentation defects, thus achieving the goal of eliminating oxide film indentation in continuous casting and rolling of aluminum alloys.

[0007] To achieve the above objectives, the technical solution adopted is as follows:

[0008] A continuous casting and rolling process for aluminum alloys is as follows: after the high-temperature molten aluminum is degassed and filtered, it is fed into the roll gap through a feed nozzle for casting and rolling.

[0009] The feed nozzle and the roller gap are purged with inert gas to form a cyclone protection zone that covers and protects the molten aluminum.

[0010] Furthermore, the inert gas is argon.

[0011] Furthermore, the angle between the inert gas purging direction and the feed nozzle is 10-20°.

[0012] Furthermore, the flow rate of the inert gas is 50-60 Nm. 3 / min, pressure 0.2-0.4MPa, temperature 15-25℃.

[0013] Furthermore, the inert gas is purged through multiple parallel outlets to form an air curtain.

[0014] Furthermore, the inert gas is continuously purged at the groove at the front end of the feed nozzle.

[0015] Furthermore, the groove is located 6-10mm from the tip of the feed nozzle.

[0016] Furthermore, the groove is a semi-circle with a diameter of 5-6 mm.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The technical solution of this invention controls the formation of oxide film in continuous aluminum alloy casting and rolling from the source. It uses an inert gas—argon—to protect the high-temperature molten aluminum from contact with air, preventing oxide film formation on the surface and eliminating oxide film indentation defects. Simultaneously, it avoids direct blowing of room-temperature inert gas onto the surface of the high-temperature molten aluminum, which could lead to solidification and crust formation. Argon or nitrogen is used for degassing and refining in continuous aluminum alloy casting and rolling. This gas source can be used; continuously introducing inert gas through the gap between the casting roll and the nozzle can protect the surface of the high-temperature molten aluminum from oxidation. Attached Figure Description

[0019] Figure 1 This is a diagram of the continuous casting and rolling process of aluminum alloy. In the diagram, H1 is the thickness of the aluminum strip, H2 is the gap between the casting nozzle and the roll, L1 is the casting and rolling zone, L2 is the solid phase zone, L3 is the liquid phase zone, L4 is the distance from the argon purging position to the front end of the casting nozzle, and β is the angle between the argon purging position and the casting nozzle material plane.

[0020] Figure 2 The diagram shows the design of the feed nozzle and the location of the gas purging. In the diagram, β is the angle between the argon purging and the casting nozzle plane, and L4 is the distance from the groove to the front end of the feed nozzle.

[0021] Figure 3 This is a schematic diagram and AA sectional view of a special casting nozzle purger; in the figure, L5 is the length of the purge nozzle, H is the opening degree of the nozzle, D is the diameter of the purge pipe, and d is the diameter of the air supply pipe.

[0022] Figure 4 This is a picture of the actual feed nozzle with grooves. Detailed Implementation

[0023] To further illustrate the continuous casting and rolling process for aluminum alloys according to the present invention and achieve the intended purpose of the invention, the following detailed description, in conjunction with preferred embodiments, details the specific implementation, structure, features, and effects of the continuous casting and rolling process for aluminum alloys proposed according to the present invention. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable manner.

[0024] The following will provide a more detailed description of a continuous casting and rolling process for aluminum alloys according to the present invention, with reference to specific embodiments:

[0025] The continuous casting and rolling process for aluminum alloys described in this invention uses an inert gas to form a cyclone protection zone, which can also protect the surface of the high-temperature molten aluminum that was originally exposed to the air, preventing the formation of an oxide film, thereby achieving continuous casting and rolling without oxide film pressing in quality defects.

[0026] Example 1.

[0027] The specific steps are as follows:

[0028] On a φ850*1700mm inclined casting and rolling mill, when producing 1100 alloy aluminum cast coils with a specification of 6.7×1010, the high-temperature molten aluminum is degassed and filtered before being fed into the roll gap through the feed nozzle for casting and rolling. Figure 1 H1 is the thickness of the aluminum strip, H2 is the gap between the casting nozzle and the roll, L1 is the casting and rolling zone, L2 is the solid phase zone, and L3 is the liquid phase zone.

[0029] 8±2mm at the tip of the feed nozzle Figure 1 A groove is provided at position L4 (in the middle), and inert gas is continuously blown into the groove at the front end of the feed nozzle, away from the feed nozzle port. The external structure of the feed nozzle groove is as follows. Figure 2 As shown in the picture, the actual product is as follows. Figure 4 As shown (the actual object is made at a certain angle during production, and this angle is...) Figure 1 The β in the design allows the dedicated casting nozzle purger to be directly mounted on the inclined surface, avoiding problems such as angle instability caused by improper installation or long-term installation. The angle between the inert gas purging direction and the horizontal line of the feed nozzle is 10-20°, that is, the angle of β is 10-20°.

[0030] The flow rate of the inert gas is 50-60 Nm. 3 / min, pressure 0.2-0.4MPa, temperature 15-25℃.

[0031] By continuously purging with inert gas, a cyclone protection zone is formed between the feed nozzle (usually called the casting nozzle) and the roll gap, covering and protecting the molten aluminum. This protects the molten aluminum, preventing the high-temperature molten aluminum exposed in the gap from contacting the air and thus preventing the formation of an oxide film.

[0032] The inert gas is continuously supplied with argon gas to form a cyclone protection zone in the gap between the roll and the upper and lower parts of the casting nozzle using a dedicated casting nozzle purger. This dedicated casting nozzle purger has multiple parallel air outlets for purging, forming an air curtain to prevent high-temperature molten aluminum from dripping.

[0033] The structure of the dedicated casting nozzle purger is as follows: Figure 3 As shown, a gas supply connector (the diameter D of the purge pipe is larger than the diameter d of the gas supply connector) is installed inside the purge pipe. Multiple purge flat-mouth pipes (usually 11) are installed side by side, connected to the gas supply connector. L is the length of the purge flat-mouth pipe, and H is the opening degree of the flat-mouth pipe. Inert gas enters from both ends of the gas supply connector and exits from the purge flat-mouth pipes.

[0034] Example 2.

[0035] The method of Example 1 was used, with argon gas purging. The groove was located 8 mm from the tip of the feed nozzle, and the angle β was 20°. The differences were in the gas flow rate, pressure, and temperature. A control group (CK) was set up: without inert gas protection.

[0036] On an inclined casting and rolling mill with a model of φ850*1700mm, aluminum alloy grade 1100 aluminum cast coils with a specification of 6.7×1010 were produced. The cast and rolled billets were then subjected to subsequent rolling processing, and the surface quality was measured. See Table 1 for details.

[0037] Table 1

[0038]

[0039]

[0040] As shown in Table 1, when the flow rate of the inert gas is 50-60 Nm... 3 The product quality can be guaranteed at a pressure of 0.2-0.4 MPa and a temperature of 15-25℃.

[0041] Example 3.

[0042] Using the method of Example 1, argon gas was used for purging at a flow rate of 55 Nm. 3 The pressure was 0.3 MPa, and the temperature was 20°C (these conditions are preferred in Example 2). The difference was that the groove was located at the front end of the feed nozzle, and the angle of β was different. A control group CK was also set up: without inert gas protection.

[0043] On an inclined casting and rolling mill with a model of φ850*1700mm, aluminum alloy grade 1100 aluminum cast coils with a specification of 6.7×1010 were produced. The cast and rolled billets were then subjected to subsequent rolling processing, and the surface quality was measured. See Table 2 for details.

[0044] Table 2

[0045]

[0046]

[0047] Note: In the table, number 1 indicates that the groove is located 0mm at the front end of the feed nozzle, meaning that no groove is set and the high-temperature aluminum liquid is directly blown out.

[0048] Example 4.

[0049] Using the method of Example 1, argon gas was used for purging at a flow rate of 55 Nm. 3 / min, pressure is 0.3MPa, temperature is 20℃, located 8mm from the front end of the feed nozzle, angle β is 15° (the conditions here are preferred in Examples 2-3), the difference lies in the shape and size of the groove.

[0050] On an inclined casting and rolling mill with a model of φ850*1700mm, aluminum alloy grade 1100 aluminum cast coils with a specification of 6.7×1010 were produced. The cast and rolled billets were then subjected to subsequent rolling processing, and the surface quality was measured. See Table 3 for details.

[0051] Table 3

[0052] 1 square 5mm side length Liquid level stability Oxide film 2 isosceles triangle 5mm side length Liquid surface fluctuation It has surface ripples and an oxide film. 3 semicircle 4mm in diameter Liquid surface fluctuation Occasionally there are surface ripples, but no oxide film. 4 semicircle 5mm in diameter Liquid level stability No oxide film, no ripples 5 semicircle 6mm in diameter Liquid level stability No oxide film, no ripples 6 Two-thirds of a circle 5mm in diameter Liquid level stability No ripples, occasionally with oxide film 7 One-third circle 5mm in diameter Liquid surface fluctuation It has ripples and no oxide film.

[0053] Referring to Table 3, a semi-circular shape with a diameter of 5-6 mm is preferred for the groove.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A continuous casting and rolling process for aluminum alloys, characterized in that, The continuous casting and rolling process is as follows: after the high-temperature aluminum liquid is degassed and filtered, it is fed into the roll gap through the feed nozzle for casting and rolling. The feed nozzle and the roller gap are purged with inert gas to form a cyclone protection zone to cover and protect the high-temperature aluminum liquid; The inert gas is continuously purged at the groove at the front end of the feed nozzle; The angle between the inert gas purging direction and the feed nozzle is 10-20°; The inert gas has a flow rate of 50-60 Nm³ / min, a pressure of 0.2-0.4 MPa, and a temperature of 15-25℃. The groove is located 6-10mm from the tip of the feed nozzle; The groove is a semi-circle with a diameter of 5-6 mm.

2. The continuous casting and rolling process according to claim 1, characterized in that, The inert gas mentioned is argon.

3. The continuous casting and rolling process according to claim 1, characterized in that, The inert gas is purged through multiple parallel outlets to form an air curtain.

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