Continuous Casting Equipment

Abstract

The present invention relates to a continuous casting apparatus for producing composite metal products, comprising a nozzle located between a tundish and a mold, an upper part located downstream of the tundish, a dome located at the inlet of the upper part and provided with means for dividing the initial flow of liquid metal, an inner wall located below the dome and forming at least two mixing chambers, means for powder injection through the dome to allow mixing with the liquid metal, and a lower part composed of at least one central channel and side channels that allow the liquid metal to flow into the mold through at least one outlet of each channel, the side channels being longer than the central channel. The present invention also relates to a method of continuous casting using the continuous casting apparatus related to the present invention.

Description

[Technical Field]

[0001] The present invention relates to continuous casting equipment, and more particularly to an improved continuous casting nozzle design adapted for producing complex metal products. [Background technology]

[0002] Continuous casting of steel is a well-known process. It involves pouring liquid metal from a ladle into a tundish, designed to regulate the flow, and then pouring the liquid metal into the top of a vertically reciprocating, water-cooled, bottomless copper mold. The solidified blank is removed from the bottom of the mold by rollers. The liquid metal is introduced into the mold by a tubular duct called a nozzle, which is located between the tundish and the mold.

[0003] However, this simple device is not suitable for casting composite metal products. The nozzle is a simple duct and can only be used as a pouring tool for the liquid metal between the tundish and the mold. Therefore, the nozzle and the casting method must be modified to enable the casting of composite metal products.

[0004] Japanese Patent Application No. 11197807 describes a continuous casting nozzle for producing multi-layered cast pieces, which is formed of a vertical duct having a plurality of discharge ports in the vertical direction, the interior of which is divided by partition walls that form a plurality of molten steel flow paths, and which has one or more ports for adding raw materials.

[0005] The described continuous casting nozzle allows two molten metals with different compositions to be injected into a mold at different heights, thus forming two liquid metal pools, an upper pool and a lower pool, each with a different composition. The metal in the upper pool solidifies first, forming a shell with the composition of the upper pool. The metal in the lower pool then solidifies inside the shell, forming the bulk of the material and with the composition of the lower pool, thus producing a composite metal product.

[0006] When producing composite metal products by continuous casting, to obtain a product of excellent quality, it is necessary to ensure very good stability of the two liquid metal reservoirs in the mold and the liquid metal flow from the nozzle, as well as very good homogeneity of the composition of each reservoir.

[0007] Japanese Patent Application No. 11197807 uses a static magnetic field and injects different liquid metal flows above and below the magnetic field to stabilize two reservoirs.

[0008] However, the solutions proposed in the prior art do not provide sufficient solutions with regard to the stability of the different liquid metal flows and the homogeneity of the liquid metal pool. Furthermore, the specific magnetic fields complicate the casting operation. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 11-197807 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention discloses a continuous casting nozzle for producing composite metal products with an improved design, allowing for better stability of the liquid metal flow and better homogeneity of the liquid metal pool with a simpler device. [Means for solving the problem]

[0011] The first object of the present invention is a continuous casting apparatus for producing composite metal products, which comprises a nozzle 1, a tundish 2 and a mold 3, said nozzle 1 being located between the tundish 2 and the mold 3, said nozzle 1 comprising: an upper part 4 arranged downstream of the tundish 2 with respect to the direction of advance of the liquid metal; a dome 6 arranged at the inlet of the upper part 4, said dome 6 comprising means for dividing the initial flow of liquid metal into at least two separate flows; an inner wall 8 located below the dome 6 and defining at least two mixing chambers 9a, 9b, in which the separate liquid metal streams flow respectively; means for powder injection 10 through the dome 6 into at least one of said chambers 9a, 9b, in order to allow mixing with the liquid metal flowing into said chambers 9a, 9b; a lower part 5 consisting of at least a central channel 12a and side channels 12b, 12c extending from the upper part 4 into the mold 3, said channels 12a, 12b, 12c allowing liquid metal to enter the mold 3 through at least one outlet 13, 14 of each channel 12a, 12b, 12c, said central channel 12a being connected to one of said chambers 9a, 9b and said side channels 12b, 12c being connected to at least the other chamber 9b, said side channels 12b, 12c being longer than said central channel (12a); Equipped with.

[0012] A continuous casting apparatus according to the invention may also have the optional features listed below, considered individually or in combination:

[0013] the central channel 12a has at least two outlets 13, the central channel 12a has at least four lateral outlets 13 located in the same horizontal plane, the lateral outlets 13 of said central channel 12a are arranged with their axes towards the central zone of the face of the mould 3; the dome 6 further comprises at least one means for gas injection 11 through the dome 6, the dome further comprises a support arm 7, The means for powder injection 10 and the means for gas injection 11 are located partly in said support arm 7 .

[0014] A second object of the present invention is to provide a method for continuous casting of a composite metal product using a continuous casting nozzle 1 according to the present invention, comprising: The liquid metal is poured into a tundish 2 located above the continuous casting nozzle 1, - the liquid metal flows from a tundish 2 into the upper part 4 of the casting nozzle 1 to create an initial flow; - said initial flow impinges on a dome 6, thus separating the initial flow into a defined number of separate flows; - said separate streams enter the mixing chambers 9a, 9b of the nozzle 1, - a powder is injected into one of said chambers 9a, 9b and mixed with the flow of liquid metal entering said chamber 9a, 9b, thus modifying its composition; the separate streams are then distributed to the lower channels 12a, 12b, 12c of the continuous casting nozzle 1, The liquid metal is poured into the mold 3 through the outlets 13, 14 of the channels 12a, 12b, 12c, with the liquid metal flowing through the side channels 12b, 12c pouring deeper into the mold 3 than the liquid metal entering the central channel 12a, thus forming two separate pools 14, 15 of liquid metal within the mold 3.

[0015] The method of continuous casting according to the invention may also have the optional features listed below, considered individually or in combination:

[0016] -The liquid metal is steel, - the powder is poured into a chamber connected to the central channel 12a, the liquid metal in the upper reservoir 15 of the mold 3 is composed of base metal from the tundish 2 mixed with the powder injected below the dome 6, and the liquid metal in the lower reservoir 16 of the mold 13 is composed solely of base metal from the tundish 2; the powder is injected into at least one chamber connected to the side channels 12b, 12c, The liquid metal in the upper reservoir 15 of the mold 3 consists only of base metal from the tundish 2, and the liquid metal in the lower reservoir 16 of the mold 3 consists of base metal from the tundish 2 mixed with the powder injected under the dome 6.

[0017] The invention will now be described in a non-limiting manner with reference to the following figures: [Brief explanation of the drawings]

[0018] [Figure 1] 1 is an overall view of a nozzle according to the present invention in use; [Figure 2] FIG. 1 is a bottom view of the lower portion of the nozzle. [Figure 3] FIG. 10 is a top view of a dome for a bulk alloying embodiment. [Figure 4] FIG. 10 is a top view of the dome for an embodiment of shell alloying. [Figure 5] 2 is a cross-sectional view AA of the top of the nozzle below the dome of FIG. 1. [Figure 6] BB is a cross-sectional view of the bottom of the nozzle into the mold showing the flow. [Figure 7] FIG. 1 is a view of the submerged portion of the nozzle showing the flow within the mold. [Figure 8] 1 is a cross-sectional view of a composite metal product obtained by continuous casting. [Figure 9] FIG. 2 is a cross-sectional view of the mixing chamber of the nozzle of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0019] Figure 1 shows a nozzle 1 positioned between a tundish 2 and a mold 3. The nozzle consists of an upper part 4 and a lower part 5.

[0020] The dome 6 is positioned at the entrance to the upper part 4 and partially closes it. The top of the dome 6 preferably has a slope of a certain angle, for example, greater than 15°. The dome 6 also preferably has sides that form a slope and a sharp edge. The dome 6 is fixed to the upper part 4 by one or more support arms 7.

[0021] An inner wall 8 located below the dome 6 forms at least two mixing chambers 9a, 9b in the upper part 4. In the configuration presented in Figure 1, there are two chambers 9a, 9b.

[0022] Also included in the upper part 4 are means for powder injection 10 and means for gas injection 11, each located partially on one of the support arms 7 and passing through the dome 6. The means for powder injection 10 can be, for example, an endless screw connected to a powder reservoir.

[0023] FIG. 3 shows a configuration of a dome 6 having three support arms 7, one of which has one passage for powder injection 10 arranged in one of the support arms 7 and two passages for gas injection 11 arranged in the other two support arms 7.

[0024] Figure 4 shows another configuration of the dome 6, also having three support arms 7, but unlike the one shown in Figure 3, in which two support arms 7 are arranged with two passages for powder injectors 10 and the other support arm 7 is arranged with one passage for gas injector 11. In this configuration, the two passages for powder injectors 10 can be connected to two different powder injectors, each with a different type of powder.

[0025] The dome 6 can also have other configurations with fewer or more support arms. For example, a configuration with four support arms 7 can be envisaged.

[0026] As shown in FIG. 1, the lower portion 5 of the nozzle 1 is comprised of three channels 12a, 12b, and 12c extending from the mixing chambers 9a and 9b in the upper portion 4 and terminating in the mold 3, with at least one outlet 13 for each channel 12a, 12b, and 12c. In this configuration, the side channels 12b and 12c open into the mold 3 by one bottom outlet 14 for each channel, and the central channel 12a opens into the mold by at least two outlets 13. FIG. 2 shows an enlarged view of one side of the bottom of the lower portion 5 of the nozzle 1 in the configuration shown in FIG. 1. The axes of the lateral outlets 13 form an angle β with the horizontal. The angle β is preferably between 0° and 20°. The angle is downward.

[0027] In this embodiment, the channels 12a, 12b, and 12c are circular. In a preferred embodiment, the side channels 12b and 12c have a triangular cross section with rounded corners. In a preferred embodiment, the central channel has a rectangular cross section and four outlets 13 arranged in the same horizontal plane, two outlets on one side of the nozzle and two outlets on the other side of the nozzle. This configuration positions the axes of the lateral outlets 13 toward the central zone of the mold face. A preferred configuration is shown in Figure 6.

[0028] Figure 5 shows a cross section AA of the nozzle 1 in the configuration described in Figure 1. Figures 3 and 4 are arranged in the same orientation as Figure 5. When Figure 3 is superimposed with Figure 5, a cross section of the nozzle 1 above the dome 6 is obtained. The same applies to Figure 4 in conjunction with Figure 5 to obtain a view of another configuration.

[0029] As shown in Figure 5, the inner wall 8 has a V-shape, thus forming two mixing chambers 9a, 9b of different volumes. The chamber 9a located inside the V-shape is connected to a central channel 12a, and the chamber 9b located outside the V-shape is connected to side channels 12b, 12c.

[0030] In other configurations, the interior wall 8 has a different shape and forms a different number of chambers, for example a Y-shape could form three chambers of different volumes, or a simple wall could form two chambers of exactly the same volume.

[0031] 1, the side channels 12b, 12c are longer than the central channel 12a and therefore open deeper into the mold 3. In this embodiment, the three channels are aligned as shown in FIG.

[0032] Other configurations are possible, for example, a third side channel can be added that is not aligned with the other channels 12a, 12b, 12c, thus forming a different shape.

[0033] In a preferred embodiment, the ratio of the diameter of the lateral outlet 13 to the distance between the lateral outlet 13 and the mold 3 is greater than 0.5 and less than 1.

[0034] In a preferred embodiment, the ratio of the diameter of the lateral outlet 13 to the diameter of the central channel 12a is greater than 1.8 and less than 2.2.

[0035] The present invention has two preferred embodiments for its use, referred to as bulk alloying and shell alloying, respectively. Only the differences between the two preferred embodiments will be described separately. The present invention in its use form is shown in Figure 1.

[0036] Liquid metal of a defined composition is poured from a ladle into a tundish 2. In a preferred embodiment, the liquid metal is steel, and the use of the nozzle 1 will be described therewith. The steel enters the upper part 4 of the continuous casting nozzle 1, thus creating an initial flow. A stopper rod 19 allows for control of the initial flow rate.

[0037] Dome 6 is positioned in the path of the steel, causing the initial flow to impinge on the dome. The slope of dome 6 forces the steel to flow toward its edges. Support arms 7 create distinct regions on dome 6, dividing the steel into multiple separate flows. The number of separate flows is determined by the design of dome 6 and its support arms 7. In this particular embodiment, the number of separate flows is three.

[0038] The separate streams then flow into different mixing chambers 9a and 9b. Figure 9 shows a cross-sectional view of the mixing chamber. In this configuration, part of the stream flows into the inner V-shaped chamber 9a, and the other part flows into the outer V-shaped chamber 9b. Powder is injected into one of the mixing chambers 9a and 9b simultaneously. The chamber design with a large cross-section at the top allows the steel to flow down the dome like a waterfall, allowing the powder to be injected into the stream without coming into contact with the powder injection means. Reducing the cross-section of the chamber allows the steel to slow down and accumulate in chambers 9a and 9b. Reducing the cross-section of the chamber allows the steel to be stirred within the chamber. As a result, the powder can efficiently mix with the steel in said chambers 9a and 9b, changing its composition and beginning to melt. This process homogenizes the liquid steel into which the powder is injected. The reduction in the cross-section of the chamber can be achieved by various wall configurations. For example, this reduction can be done in a regular incline, in stages, or by any means for reducing the cross-section.

[0039] The powders injected into the steel can be of various compositions, for example FeSi, Ni, FeAl, FeTi, FeCr, FeNb, FeB, FeCe, FeMo, etc.

[0040] The process of powder addition differs between the two preferred embodiments: in the bulk alloying embodiment, the powder is injected into the outer V-shaped chamber 9a by at least one powder injection 10, with Figure 3 showing only one injection, while in the shell alloying embodiment, the powder is injected into the inner V-shaped chamber 9b by at least one powder injection 10, with Figure 4 showing two powder injections.

[0041] In both embodiments, powder injection is facilitated by gas injection 11, which creates a gas flow that keeps the steel flowing down dome 6 towards the exterior of top 4, thus creating a steel-free zone below dome 6. This hollow area prevents contact between the steel and powder injection 10, thus avoiding potential clogging of powder injection 10.

[0042] The gas is preferably a non-oxidizing gas, such as Ar, to prevent reaction with the steel during casting.

[0043] After pouring, the two mixing chambers 9a, 9b contain two steels with different compositions.

[0044] The steel then flows into the channels 12a, 12b, 12c in the lower part 5 of the nozzle 1, which are connected to the chambers after the reduction of the cross section, as shown in Fig. 1 of Fig. 9. The steel in the chamber 9a located inside the V-shape flows into the central channel 12a, and the steel in the chamber 9b located outside the V-shape flows into the side channels 12b, 12c. The different steels are then poured into the mold 3 through the outlets 13, 14 of the channels 12a, 12b, 12c.

[0045] The steel from side channels 12b, 12c is poured deeper into mold 3 because side channels 12b, 12c are longer than central channel 12a. This configuration allows two types of steel to be poured into mold 3 at different heights, thus forming two pools of steel with different compositions: upper pool 15 and lower pool 16. Upper pool 15 is formed by the steel from central channel 12a, and lower pool 16 is formed by the steel from side channels 12b, 12c.

[0046] The outlets 13, 14 of the nozzle 1 are immersed in different steel pools during use: the bottom outlets 14 of the side channels 12b, 12c are immersed in a lower pool 16 and the lateral outlet 13 of the central channel 12a is immersed in an upper pool 15.

[0047] The composition of the pool varies depending on the embodiment.

[0048] In a bulk alloying embodiment, the composition of the upper pool 15 is that of only the steel coming from the tundish 2. The composition of the lower pool 16 is a combination of the composition of the steel coming from the tundish 2 and the composition of the injected powder.

[0049] In the shell alloying embodiment, the composition of the upper pool 15 is a combination of the composition of the steel from tundish 2 and the composition of the poured powder. The composition of the lower pool 16 is the composition of only the steel from tundish 2.

[0050] In both embodiments, in the mold 3, the steel in the upper pool 15 solidifies first, thus forming the shell 17. Then, the steel in the lower pool 16 solidifies inside the shell 17, thus forming the bulk of the material 18. After complete solidification, the resulting material is a composite metal product in which the composition of the shell differs from the bulk, as shown in Figure 8.

[0051] To cast a composite metal product of sufficient quality, each pool must have a homogeneous composition and the boundaries between them must be stable. These factors are influenced by the behavior of the different liquid metal streams coming from the nozzle 1.

[0052] The design of the nozzle 1, with at least four side outlets 13, whose axes are positioned towards the central zone of each mold face, as shown in Figure 6, allows the flow in the mold to be symmetrical in all directions, thus ensuring the homogeneity of the two pools (15, 16).

[0053] These flows, generated by the nozzle design, ensure the stability of the interface between the two liquid metal pools (15, 16).

[0054] For example, in the configuration shown in Figure 7, the flow from the lateral outlet 13 forms a main upward flow 20 and a secondary downward flow 21 with a smaller flow rate in the upper pool 15 when it hits the surface of the mold 3. Meanwhile, the flow from the bottom outlet 15 generates a flow in the form of a vortex 22 in the lower pool 16.

[0055] The design of these outlets can affect the stability and homogeneity of the interface between the two reservoirs, since they affect the initial direction and velocity of the flow. Those skilled in the art determine the characteristics of the outlets 13, 14 to optimize these parameters. Among the characteristics that can be considered are the outlet diameter relative to the channel diameter, the outlet diameter relative to the distance between the outlet 13 and the mold 3, and the angle β of the outlet axis relative to the horizontal.

[0056] In a preferred embodiment, the axis of the lateral outlet 13 has an angle β of 0° to 20° with respect to the horizontal, since this angle makes it possible to achieve optimal stability of the two reservoirs.

[0057] In a preferred embodiment, the ratio of the diameter of the lateral outlet 13 to the distance between the outlet 13 and the mold is greater than 0.5 and less than 1.

[0058] In a preferred embodiment, the ratio of the diameter of the lateral outlet 13 to the diameter of the central channel 12a is greater than 1.8 and less than 2.2.

[0059] In a preferred embodiment, the nozzle 1 is primarily constructed from a refractory material surrounded by a metal ring.

[0060] In its application, the continuous casting nozzle 1 meets expectations regarding stability and homogeneity. It allows for a stable casting speed, and the different liquid metal flows allow for great stability and homogeneity of the two pools in the mold 3. This stability results in a high-quality semi-finished product with a clearly defined composition gradient between the shell and the bulk.

Claims

1. A continuous casting apparatus for producing a composite metal product, comprising a nozzle (1), a tundish (2), and a mold (3), wherein the nozzle (1) is located between the tundish (2) and the mold (3), and the nozzle (1) comprises: an upper part (4) arranged downstream of the tundish (2) relative to the direction of movement of the liquid metal; a dome (6) placed at the entrance of the upper part (4), said dome (6) comprising means for dividing the initial flow of liquid metal into at least two separate flows; an inner wall (8) located below the dome (6) and forming at least two mixing chambers (9a, 9b), said separate liquid metal streams flowing in each of said chambers (9a, 9b), - means for injecting (10) powder through the dome (6) into at least one of said chambers (9a, 9b) to allow mixing with the liquid metal flowing into said chambers (9a, 9b); a lower part (5) consisting of at least a central channel (12a) and side channels (12b, 12c) extending from the upper part (4) into the mold (3), said channels (12a, 12b, 12c) allowing liquid metal to enter the mold (3) through at least one outlet (13, 14) of each channel (12a, 12b, 12c), said central channel (12a) being connected to one of said chambers (9a, 9b) and said side channels (12b, 12c) being connected to at least the other chamber (9b), said side channels (12b, 12c) being longer than said central channel (12a); A continuous casting apparatus comprising:

2. 2. The continuous casting apparatus of claim 1, wherein the central channel has at least two outlets (13).

3. 3. A continuous casting apparatus according to claim 2, wherein the central channel has at least four lateral outlets (13) located on the same horizontal plane.

4. 4. A continuous casting device according to claim 3, wherein the lateral outlets (13) of the central channel (12a) are arranged with their axes towards the central zone of the face of the mold (3).

5. 5. A continuous casting apparatus according to any one of claims 1 to 4, wherein the dome (6) further comprises at least one means for gas injection (11) through the dome (6).

6. 6. A continuous casting apparatus according to any one of claims 1 to 5, wherein the dome further comprises a support arm (7).

7. 6. A continuous casting device according to claim 4 or 5, wherein the means for powder injection (10) and the means for gas injection (11) are located partly in the support arm (7).

8. 8. A method for continuously casting a composite metal product using a continuous casting apparatus according to any one of claims 1 to 7, comprising the steps of: - liquid metal is poured into a tundish (2) located above the continuous casting nozzle (1); - the liquid metal flows from the tundish (2) into the upper part (4) of the casting nozzle (1) to create an initial flow; - said initial flow impinges on a dome (6), thus separating said initial flow into a defined number of separate flows; - said separate streams enter the mixing chamber (9a, 9b) of the nozzle (1), - a powder is injected into one of said chambers (9a, 9b) and mixes with the flow of liquid metal entering said chambers (9a, 9b), thus modifying its composition; - the separate streams are then distributed to the lower channels (12a, 12b, 12c) of the continuous casting nozzle (1), - the liquid metal is poured into the mould (3) by the outlets (13, 14) of the channels (12a, 12b, 12c), the liquid metal flowing through the side channels (12b, 12c) being poured deeper into the mould (3) than the liquid metal entering the central channel (12a), thus forming two separate pools of liquid metal (15, 16) in the mould (3); method.

9. The method of claim 8 wherein the liquid metal is steel.

10. 10. The method according to claim 8 or 9, wherein the powder is injected into a chamber connected to the central channel (12a).

11. 11. The method according to claim 10, wherein the liquid metal in the upper reservoir (15) of the mold (3) consists of base metal from the tundish (2) mixed with powder injected below the dome (6), and the liquid metal in the lower reservoir (16) of the mold (13) consists solely of base metal from the tundish (2).

12. 10. The method according to claim 8 or 9, wherein the powder is injected into at least one chamber connected to a side channel (12b, 12c).

13. 13. The method according to claim 12, wherein the liquid metal in the upper reservoir (15) of the mold (3) consists solely of base metal from the tundish (2), and the liquid metal in the lower reservoir (16) of the mold (3) consists of base metal from the tundish (2) mixed with powder injected below the dome (6).

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