Apparatus and method for continuous casting of metal products

Abstract

An apparatus (10) for the continuous casting of metal products has an ingot mold (11) and a nozzle (12) for supplying molten metal (I), the nozzle (12) comprising at least one axial main outlet (13) configured to conduct the molten metal (I) substantially to the lower part of the ingot mold (11) and a plurality of secondary outlets (14) configured to conduct the molten metal (I) substantially to the side wall (15) of the ingot mold (11).

Description

Technical Field

[0001] The present invention relates to an apparatus and a method for the continuous casting of metal products, in particular slabs or products having a rectangular cross-section with a width much greater than the thickness.

Background Art

[0002] Continuous casting apparatuses including an ingot mold configured to cast metal products, in particular slabs, are known.

[0003] The molten metal is introduced into the ingot mold and gradually solidifies with the formation of a solid skin.

[0004] When leaving the ingot mold, the casting has a solidified outer shell that functions to enclose the liquid metal still present inside. The ingot mold further demarcates a casting line along which the metal product in the solidification process gradually advances and completely solidifies downstream of the ingot mold. The solidified product is then sent to a rolling process having, for example, an endless process, or cut into a plurality of sections so as to be rolled in a coil-to-coil or semi-endless process, or taken out from the line and rolled in a subsequent process.

[0005] The ingot mold is supplied with molten metal from a tundish by means of at least one SEN type nozzle (Submerged Entry Nozzle), i.e., an outlet of the metal arranged at a level below the level of the liquid metal meniscus.

[0006] The nozzle may be configured to have a substantially axial main outlet or a plurality of secondary outlets configured to mainly direct the molten metal to the lower part of the ingot mold, and a plurality of secondary outlets configured to mainly direct the molten metal towards the side walls of the mold.

[0007] According to this type of nozzle, not only this, but also in the ingot mold, it is difficult to regulate the speed and direction of the flow in order to equalize the flow of the metal generated from the outlet and to make the casting process as efficient and productive as possible.

[0008] Problems with such non-uniform and unstable molten metal flow occur particularly in the meniscus zone, that is, at the upper level of the metal in the ingot mold.

[0009] Existing continuous casting apparatuses having an ingot mold and a SEN cannot effectively control the uniformity of the metal flow in the mold for both the flow from the central outlet and the side outlets of the SEN, nor can they regulate these speeds and / or directions.

[0010] Furthermore, due to the limitations of existing apparatuses, it is difficult to achieve high-speed continuous casting in order to obtain the desired high productivity of the apparatuses.

[0011] Therefore, there is a need to complete an apparatus for continuous casting of metal products that overcomes the drawbacks in the prior art and can satisfy all the requirements for control of such metal flow conditions.

[0012] In particular, one object of the present invention is to provide an apparatus for continuous casting of multi-purpose metal products that can regulate the flow of the metal material in the ingot mold, for example, in terms of speed and direction, so that the productivity of the apparatus can be improved by 30 to 40% compared to existing apparatuses.

[0013] Another object of the present invention is to provide an apparatus for continuous casting of metal products that allows for effective and productive continuous casting even at high speeds.

[0014] Another object of the present invention is to provide an apparatus for continuous casting of metal products that also allows for effective control of medium-speed and low-speed liquid metals.

[0015] Another object of the present invention is to provide an apparatus for continuous casting of metal products that converts and maintains the metal flow in the mold into a stable and optimized flow pattern even in the meniscus zone for the best quality of the product.

[0016] Another object of the present invention is to provide an apparatus for continuous casting of metal products that can control the metal flow from the outlet of the SEN.

[0017] Another object of the present invention is to complete an effective and simple method for continuous casting of metal products.

[0018] The applicant invented, experimented with, and embodied the present invention to overcome the drawbacks in the prior art and obtain these and other objects and advantages.

Summary of the Invention

[0019] The present invention is specified and characterized by the description in the independent claims. The dependent claims explain other features of the present invention or modifications to the main idea of the invention.

[0020] Corresponding to the above object, an apparatus for continuous casting of metal products according to the present invention includes an ingot mold and a submerged type (SEN) nozzle for supplying molten metal, and the ingot mold has a substantially rectangular cross-section provided by narrow side walls and wide side walls.

[0021] The supply nozzle is provided to have at least one substantially axial main outlet configured to mainly guide the molten metal to the lower part of the ingot mold, and a plurality of secondary outlets configured to mainly guide the molten metal to the narrow side wall of the ingot mold.

[0022] According to one characteristic aspect of the present invention, the apparatus includes at least one first electromagnetic system that is at least associated with the opposing wide sidewalls of the ingot mold and is configured to mainly regulate the flow of the molten metal exiting the main outlet, and at least one different second electromagnetic system that is associated with the opposing wide sidewalls and is configured to mainly regulate the flow of the molten metal exiting the secondary outlet.

[0023] According to the means of the electromagnetic system associated with the ingot mold, it is advantageous in that it can regulate the flow of the metal material from the outlet of the nozzle, for example, with respect to speed and direction, also corresponding to the meniscus of the ingot mold, and it is possible to obtain better uniformity of the metal bath. Compared with existing apparatuses, the productivity of the apparatus increases by 30 to 40%, and continuous casting in high-speed slabs is also possible.

[0024] According to another aspect of the present invention, the first electromagnetic system is located at a specific height lower than the main outlet of the nozzle.

[0025] According to another aspect of the present invention, the first electromagnetic system is a static system having two or three magnetic bodies with associated electric coils wound around them.

[0026] According to another aspect of the present invention, the first electromagnetic system is configured to at least decelerate the flow of the molten metal exiting the main outlet and bring about the possibility of stabilizing the flow exiting the secondary outlet.

[0027] According to another aspect of the present invention, the second electromagnetic system is substantially located at the height of the side outlet of the SEN.

[0028] According to another aspect of the present invention, the second electromagnetic system includes a plurality of electromagnetic stirrers located on the opposing walls of the ingot mold.

[0029] According to another aspect of the present invention, the second electromagnetic system includes the four electromagnetic stirrers located on the opposing walls that pair up.

[0030] According to another aspect of the present invention, each of the electromagnetic stirrers has a magnetic body, and a series of exciting electric coils are attached around it.

[0031] According to another aspect of the present invention, the second electromagnetic system is configured to decelerate or accelerate the flow of the molten metal exiting the secondary outlet.

[0032] According to another aspect of the present invention, the second electromagnetic system is configured to swirl the flow of the molten metal exiting the secondary outlet.

[0033] According to another aspect of the present invention, the second electromagnetic system is located above the first electromagnetic system.

[0034] The present invention also relates to a method for continuously casting a metal product, particularly a slab, the method comprising supplying molten metal to an ingot mold by means of a nozzle of the submerged type (SEN), the nozzle being configured to direct the molten metal mainly to the lower part of the ingot mold and including at least one main outlet in a substantially axial direction and a plurality of secondary outlets configured to direct the molten metal mainly to the side walls of the ingot mold. The flow of the molten metal exiting the main outlet is regulated by means of at least one first electromagnetic system located on the opposing walls of the ingot mold, and the flow of the molten metal exiting the secondary outlet is regulated by means of at least one different second electromagnetic system.

[0035] These and other aspects, features, and advantages will become apparent from the following description of several embodiments with reference to the accompanying drawings by way of non-limiting examples.

Brief Description of the Drawings

[0036]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6a-b

Figure 6c-d

Figure 7a-b

Figure 8a-b

Mode for Carrying Out the Invention

[0037] We should clarify that the expressions and terms used in this specification, and each figure in the above-mentioned attached drawings have only the function of better illustrating and explaining the present invention, and since the scope of protection is defined by the claims, these functions do not provide a non-limiting example of the present invention itself.

[0038] For ease of understanding, wherever possible, the same reference numerals are used for similar elements in the figures. It should be understood that the elements and features of one embodiment can be combined or incorporated into other embodiments as appropriate without further explanation.

[0039] Hereinafter, possible embodiments of the present invention will be described in detail with reference to one or more specific examples shown in the accompanying drawings, which are not limited thereto. The expressions and terms used herein are for the purpose of providing non-limiting examples only.

[0040] Referring to the accompanying drawings, particularly FIGS. 1 to 4, an apparatus 10 for continuous casting of metal products includes an ingot mold 11 and a nozzle 12 for supplying molten metal.

[0041] The ingot mold 11 is designed to cast a slab, and the width of the slab is much larger than its thickness. For this purpose, the ingot mold 11 has a first narrow side wall 15 and a second wide side wall 17. The narrow side wall 15 is movable to correspond to the width of the cast slab.

[0042] The nozzle 12 is of the submerged type and is provided with at least one main outlet 13 configured to direct the molten metal I mainly downward into the ingot mold 11, and a plurality of secondary outlets 14 configured to direct the molten metal mainly toward the narrow side wall 15 of the ingot mold 11. The nozzle 12 is particularly a SEN nozzle (submerged entry nozzle).

[0043] The main outlet 13 is directed substantially along the longitudinal axis L of the nozzle 12. The nozzle 12 is located substantially at the center of the ingot mold 11 during use. The secondary outlets 14 are directed substantially radially and are inclined downward. For example, it is possible to provide two secondary outlets 14 that are diametrically opposed, or a different number of secondary outlets 14.

[0044] The device 10 includes at least one first electromagnetic system 16 associated with the opposing wide sidewalls 17 of the ingot mold 11 and configured to mainly regulate the first flow F1 of the molten metal I exiting from the main outlet 13, and at least one second electromagnetic system 18 associated with the opposing wide sidewalls 17 and configured to mainly regulate the second flow F2 of the molten metal exiting from the secondary outlet 14.

[0045] The first flow F1 can be braked, and the second flow F2 can be, for example, decelerated or accelerated, and thus the intensities of the flows F1 and F2 are regulatable. At least the second flow F2 can be partially swirled as follows.

[0046] The first electromagnetic system 16 is positioned at a specific height below the main outlet 13. Substantially, the first electromagnetic system 16 is divided into two equal parts 16a and 16b, each of which is positioned on one of the wide sidewalls 17 of the ingot mold 11 in this specific case.

[0047] The first electromagnetic system 16 is a static system having two or three magnetic bodies 19a, 19b, 19c. As illustrated in the figure, a three-pole electromagnetic system 16 is shown. The corresponding electric coils 20a, 20b, 20c are wound around the magnetic bodies 19a, 19b, 19c.

[0048] The first electromagnetic system 16 is configured to at least decelerate the first flow F1 of the molten metal exiting from the main outlet 13 and, according to the case, stabilize it together with the second flow F2 exiting from the secondary outlet 14. For example, compare the examples in FIGS. 4 and 5.

[0049] Substantially, in order to regulate the first flow F1 which is generally downward and usually has a strong thrust, the first electromagnetic system 16 generates a static magnetic field in the area covering the entire width of the ingot mold 11 below the nozzle 12. The electric coils 20a, 20b, 20c are supplied with direct current to magnetize the magnetic bodies 19a, 19b, 19c.

[0050] In a configuration having three magnetic bodies 19a, 19b, 19c as illustrated in the attached drawings, for each of the two parts 16a or 16b of the first electromagnetic system 16, two magnetic bodies 19a, 19c are respectively positioned on both sides of the nozzle 12, one on the left side and the other on the right side. These magnetic bodies 19a, 19c are supplied with magnetic fields in the same direction. Since the central magnetic body 19b is positioned on the corresponding wide side wall 17, according to the front view in FIG. 5, it is substantially aligned with the main outlet 13 and thus aligned with the lower end of the nozzle 12. The magnetic body 19b is supplied with a magnetic field in a direction opposite to the magnetic fields supplied to the two side magnetic bodies 19a, 19c, thereby ensuring an overall closure for the magnetic field. This magnetic field then passes through the ingot mold 11 and the liquid metal and has a shape of "8" or "double 0" with respect to the cross-section or top view of the ingot mold 11.

[0051] In a configuration having two magnetic bodies, although not shown in the figures, the magnetic bodies are only on both sides of the nozzle 12, one on the left side and the other on the right side. The magnetic flux passes through the ingot mold 11 and the liquid metal and returns through the magnetic bodies, forming a closed ring in the shape of "0".

[0052] The second electromagnetic system 18 is positioned substantially at the height of the secondary outlet 14.

[0053] The second electromagnetic system 18 includes a plurality of electromagnetic stirrers 21a, 21b, 21c, 21d positioned on the opposing wide side walls 17 of the ingot mold 11. Preferably, the four electromagnetic stirrers 21a, 21b, 21c, 21d are paired and positioned on two corresponding walls 17. Referring to the example of the electromagnetic stirrers 21b, 21d or electromagnetic stirrers 21a, 21c in FIG. 1, the electromagnetic stirrers 21a, 21b, 21c, 21d can be positioned opposite to each other. The electromagnetic stirrers 21a - 21b or electromagnetic stirrers 21c - 21d that are paired with each other can be interconnected or coupled.

[0054] Each of the electromagnetic stirrers 21a, 21b, 21c, 21d includes a magnetic body 22 to which a series of exciting electric coils 23 are attached.

[0055] The second electromagnetic system 18 is configured to decelerate or accelerate a second flow F2 of molten metal exiting the secondary outlet 14. The second flow F2, referring particularly to FIG. 4, generally includes an upward branch F21 representing the flow of molten metal in the vicinity of the surface S of the molten metal bath and in the vicinity of the meniscus M. The flow F2 further includes a downward branch F22 that is directed downward, i.e., toward the outlet of the ingot mold 11.

[0056] The second electromagnetic system 18 is configured to swirl at least the upward branch F21 of the second flow F2, as shown in the following description.

[0057] Furthermore, the second electromagnetic system 18 is located above the first electromagnetic system 16 and is thus closer to the upper part of the ingot mold 11 where the molten metal is introduced by means of the nozzle 12.

[0058] Substantially, to regulate the second flow F2 exiting the secondary outlet 14, magnetic fields having various directions and / or intensities are generated by means of the electromagnetic stirrers 21a, 21b, 21c, 21d.

[0059] The electromagnetic stirrers 21a, 21b, 21c, 21d are excited by an alternating current whose time and phase vary. As a function of the selected configuration, in the case of a typically two-phase device, the phase shift between the currents can be 90 degrees or can be 120 degrees to create a known three-phase configuration. These configurations generate a magnetic field that varies in space and time, i.e., a "sliding magnetic field". As a function of the phase control of the current in the electric coil 23, a magnetic field can be generated that progresses in a desired direction, thus from left to right or vice versa from right to left.

[0060] By combining the electromagnetic stirrers 21a, 21b, 21c, 21d with the traveling direction of the magnetic field overlapping the second lateral flow F2, gradually different flow regulation functions can be generated, and thus different operation modes for regulating the second flow F2 can be generated. These modes can be set by means of the control system of the device 10 connected to each of the second electromagnetic system 18 and thus the electromagnetic stirrers 21a, 21b, 21c, 21d. This control system can also be connected to the first electromagnetic system 16.

[0061] Referring to FIG. 6a, in the first operation mode of the second electromagnetic system 18, magnetic fields A1, A2 are generated by means of the electromagnetic stirrers 21a, 21b, 21c, 21d including the electromagnetic stirrers 21a, 21b shown in the figure, and the magnetic fields A1, A2 are guided by the nozzle 12 toward the side wall 15 of the ingot mold 11. Thereby, the acceleration of the lateral flow F2 of the liquid metal becomes possible, and thus the speed of the molten metal moving from the secondary outlet 14 toward the meniscus M is improved.

[0062] Referring to FIG. 6b, in another operation mode of the second electromagnetic system 18, magnetic fields B1, B2 are generated by means of the electromagnetic stirrers 21a, 21b, 21c, 21d, and the magnetic fields B1, B2 are guided by the side wall 15 toward the nozzle 12. Thereby, the deceleration of the lateral flow F2 of the liquid metal becomes possible, and thus the speed of the molten metal moving from the secondary outlet 14 toward the meniscus M is decreased.

[0063] In either case, in both modes described, the goal is to obtain an amount of molten metal in motion that can ensure stability and uniformity for the casting step along the ingot mold 11.

[0064] Referring to FIGS. 6c, 6d, 7a, 7b, 8a, and 8b, in another operating mode of the second electromagnetic system 18, by generating magnetic fields R1, R2, R3, and R4, in order to homogenize the molten metal bath, particularly in the vicinity of the meniscus M, the flow F2 of the molten metal can be swirled. The magnetic fields R1 and R2 have the same direction and can be generated by electromagnetic stirrers 21a and 21b located on one wide side wall 17 of the ingot mold 11, while the magnetic fields R3 and R4 have the same direction and can be generated by electromagnetic stirrers 21c and 21d located on the opposite wide side wall 17 of the ingot mold 11. The direction of the magnetic fields R1 and R2 is opposite to the direction of the magnetic fields R3 and R4.

[0065] The above operating mode is aimed at swirling the molten metal, particularly in the vicinity of the meniscus M, and is thus generated by means of the electromagnetic stirrers 21a, 21b, 21c, and 21d located in the vicinity of the wide side walls 17 that face each other and have a surface larger than that of the ingot mold 11. Thereby, for the meniscus M, the uniformity of the temperature of the metal is improved, and the cleaning of the solidification front becomes possible.

[0066] The intensities of the magnetic fields generated on the same wall 17 of the ingot mold 11 may be the same, referring to the magnetic fields R1 and R2 in FIG. 6c, or may be different such that the magnetic field R1 has a greater intensity than the magnetic field R2, referring to the magnetic fields R1 and R2 in FIG. 6d. Referring to the magnetic fields R1 and R2 in FIGS. 6c and 6d, the directions of the magnetic fields generated on the same wall are the same.

[0067] The situation in Fig. 6d is also shown in Fig. 7a, which is a front view of a part of the ingot mold 11 where the second flow F2 is generated by a side opening having two components, namely a generally upward component and a generally downward component, and in Fig. 7b, which is a top view of how the second electromagnetic system 18 operates to equalize the second flow F2. As can be observed from the figures, the intensity of the magnetic field R3 generated by the electromagnetic stirrer 21c is smaller than the intensity of the magnetic field R4 generated by the electromagnetic stirrer 21d. It can be hypothesized that the magnetic fields R1 and R4 have the same intensity but are in opposite directions. Also, it can be hypothesized that the magnetic fields R2 and R3 have the same intensity but are in opposite directions.

[0068] Also, Fig. 7b schematically shows the direction D1 of the swirling of the molten metal in the ingot mold 11, which is generated thanks to the second electromagnetic system 18.

[0069] Figs. 8a and 8b show, respectively, a front view of a part of the ingot mold 11 where the second flow F2 is generated using a downward swirling component, and a top view of how the second electromagnetic system 18 operates to equalize the second flow F2.

[0070] In this case, the intensity of the magnetic field R1 is smaller than the intensity of the magnetic field R2, and the intensity of the magnetic field R3 is larger than the intensity of the magnetic field R4. The magnetic fields R1 and R2 generated by the electromagnetic stirrers 21a, 21b are directed in the opposite direction to the magnetic fields R3 and R4 generated by the electromagnetic stirrers 21c, 21d. It can be hypothesized that the magnetic fields R1 and R4 have the same intensity but are in opposite directions. Also, it can be hypothesized that the magnetic fields R2 and R3 have the same intensity but are in opposite directions.

[0071] Also, Fig. 8b schematically shows the direction D1 of the swirling of the molten metal in the ingot mold 11, which is generated thanks to the second electromagnetic system 18.

[0072] Therefore, the method for continuously casting a metal product according to the present invention includes supplying molten metal I to the ingot mold 11 by means of the nozzle 12. The first flow F1 of the molten metal I before exiting from the main outlet 13 of the nozzle 12 is regulated by means of at least one first electromagnetic system 16, and the second flow F2 of the molten metal exiting from the secondary outlet 14 of the nozzle 12 is regulated by the second electromagnetic system 18.

[0073] It is obvious that without departing from the field and scope of the invention defined by the claims, modifications and / or additions of parts can be made to the devices and methods for continuously casting metal products, especially slabs, as described above.

[0074] Also, although the present invention has been described with reference to some specific examples, it is obvious that a person skilled in the art will surely be able to implement many other equivalent forms of devices for continuously casting metal products that have the features described in the claims and thus fall entirely within the protection scope defined by the claims.

[0075] In the following claims, the sole purpose of the references in parentheses is for ease of reading and shall not be considered as a limiting element regarding the protection scope defined by the claims.

Claims

1. An apparatus (10) for the continuous casting of metal products, comprising an ingot mold (11) and a submerged nozzle (12) for providing molten metal (I), wherein said ingot mold (11) has a substantially rectangular cross-section provided by narrow side walls (15) and wide side walls (17), said nozzle (12) is provided with at least one axial main outlet (13) configured to mainly direct said molten metal (I) to the lower part of said ingot mold (11), and a plurality of secondary outlets (14) configured to mainly direct said molten metal (I) to said narrow side walls (15) of said ingot mold (11), said apparatus (10) comprising at least one first electromagnetic system (16) associated at least with said opposing wide side walls (17) of said ingot mold (11) and configured to mainly regulate a first flow (F1) of said molten metal (I) exiting said main outlet (13), and at least one different second electromagnetic system (18) associated with said opposing wide side walls (17) and configured to mainly regulate a second flow (F2) of said molten metal (I) exiting said secondary outlets (14), characterized in that it comprises an apparatus (10).

2. The apparatus (10) according to claim 1, characterized in that said first electromagnetic system (16) is located at a specific height lower than said main outlet (13).

3. The apparatus (10) according to claim 1 or 2, characterized in that said first electromagnetic system (16) is a static system having two or three magnetic bodies (19a, 19b, 19c) around which associated electric coils (20a, 20b, 20c) are wound.

4. The apparatus (10) according to any one of claims 1 to 3, characterized in that said first electromagnetic system (16) is configured to at least decelerate a first flow (F1) of said molten metal (I) exiting said main outlet (13) and to provide the possibility of stabilizing said first flow (F1) together with said second flow (F2) exiting said secondary outlets (14).

5. The apparatus (10) according to any one of claims 1 to 4, characterized in that said second electromagnetic system (18) is located substantially at the height of said lateral secondary outlets (14).

6. The apparatus (10) according to any one of claims 1 to 5, wherein the second electromagnetic system (18) includes a plurality of electromagnetic stirrers (21a, 21b, 21c, 21d) located on the opposing wide side walls (17) of the ingot mold (11).

7. The apparatus (10) according to claim 6, wherein the second electromagnetic system (18) includes four of the electromagnetic stirrers (21a, 21b, 21c, 21d) located on the corresponding paired wide side walls (17).

8. The apparatus (10) according to any one of claims 1 to 7, wherein each of the electromagnetic stirrers (21a, 21b, 21c, 21d) has a magnetic body (22) around which a series of exciting electric coils (23) are attached.

9. The apparatus (10) according to any one of claims 1 to 8, wherein the second electromagnetic system (18) is configured to decelerate or accelerate the second flow (F2) of the molten metal exiting the secondary outlet (14).

10. The apparatus (10) according to any one of claims 1 to 9, wherein the second electromagnetic system (18) is configured to swirl the second flow (F2) of the molten metal exiting the secondary outlet (14).

11. The apparatus (10) according to any one of claims 1 to 10, wherein the second electromagnetic system (18) is located above the first electromagnetic system (16).

12. A method for continuously casting a metal product, supplying molten metal (I) to an ingot mold (11) by means of a nozzle (12), the nozzle (12) including at least one axial main outlet (13) configured to mainly direct the molten metal (I) to the lower part of the ingot mold (11) and a plurality of secondary outlets (14) configured to mainly direct the molten metal (I) to the narrow side walls (15) of the ingot mold (11), the method comprising: regulating the first flow (F1) of the molten metal (I) exiting the main outlet (13) by means of at least one first electromagnetic system (16) associated with the opposing wide side walls (17) of the ingot mold (11), A method, characterized in that a second flow (F2) of the molten metal (I) exiting from the secondary outlet (14) is regulated by means of at least one different second electromagnetic system (18) associated with the corresponding wide side wall (17) of the ingot mold (11).

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