Secondary cooling device in a machine for continuous casting of metal products

Abstract

A secondary cooling device (12) for use in a machine (10) for continuous casting of metal products (P), in which each metal product (P) is cast, contained and guided along a motion axis (X). The secondary cooling device (12) comprises a plurality of cooling groups (G) arranged sequentially one after the other along the continuous casting machine (10). Each group (G) comprises a plurality of cooling units (17) each provided with one or more nozzles (18) arranged along the motion axis (X). The cooling units (17) of each group (G) are adjacent to each other to cover a width at least equal to the maximum width of the metal products (P) castable in the continuous casting machine (10).

Description

Technical Field

[0001] This invention relates to a secondary cooling device for a machine used in continuous casting of metal products.

[0002] Specifically, the secondary cooling device is located at the mold exit and acts on the metal product along the roller path downstream of it. By way of example only, the cast metal product can be a large billet, billet, slab, or other known type. Background Technology

[0003] As is well known, in continuous casting, the metal product transitions from a liquid to a partially solid state, reaching complete solidification at a predetermined location downstream of the casting itself. During these steps, the surface layer of the metal product (containing a liquid metal core) gradually thickens until it is completely solidified.

[0004] Initially, heat removal from the cast metal product is controlled by heat exchange with a primary cooling unit. The primary cooling unit consists of multiple cooling channels associated with or integrated with the containment walls of the mold (crystallizer).

[0005] Then, a secondary cooling device is provided downstream of the crystallizer. This secondary cooling device includes multiple nozzles distributed with rollers for supporting and guiding the metal product, and a circuit for supplying one or more cooling fluids to the nozzles.

[0006] The heat exchange mechanisms involved in the secondary cooling system are the radiator and the convection meter.

[0007] A radiation meter is a heat exchange mechanism between two surfaces at different temperatures, such as between the surface of a metal product and the surface of a roller used to support and guide the metal product.

[0008] In these types of applications, convection occurs in a forced manner by delivering one or more cooling fluids (possibly a mixture thereof) onto the metal product to be cooled.

[0009] Nozzles are typically positioned between support rollers and guide rollers to direct one or more cooling fluids directly onto the metal product. For this purpose, nozzles can be spaced apart to cover (and potentially overlap) the entire lateral dimension of the cast metal product. Furthermore, nozzles can deliver jets of cooling fluid with different shapes, depending on the type of metal product being cooled.

[0010] Typically, in continuous casting machines, nozzles can be either water-only or a combination of water and air.

[0011] In the case of nozzles that only deliver water, water is conveyed through a single orifice, or in combination with other orifices, and sprayed onto the casting product. To regulate cooling, the water flow rate at the nozzle is varied to achieve a specific convective heat exchange effect. Examples of water-only nozzles and corresponding control methods are described in patent documents WO2017 / 042059A1, WO2018 / 224304A1, and US2019 / 0054520A1.

[0012] In the case of nozzles that deliver both water and air, the addition of air expands the nozzle's adjustment range, allowing for greater control of the water flow rate. A disadvantage of this type of nozzle is the high consumption of compressed air and the corresponding energy costs associated with its production, as well as the need for dedicated management components to control the air.

[0013] Typically, nozzles are grouped into cooling units to, for example, define a uniform cooling area for the cast product, while simultaneously simplifying the construction of the circuit for supplying the nozzles, which can also become quite complex due to the quantity and type of cooling fluid used.

[0014] The circuit for supplying the nozzle includes a device for pumping cooling fluid, one or more components for regulating the flow rate, and a piping system; the components include a servo valve, a flow meter, and a pressure sensor, and the piping system, also referred to as “interconnecting piping,” fluidly connects the pumping device and one or more regulating components to the cooling unit.

[0015] Cooling units, typically arranged symmetrically with respect to the central axis of a metal product, can be grouped into rings, also known as "loops," and controlled by corresponding flow regulating components to define a uniform cooling area.

[0016] Typically, if there are "n" cooling zones within a casting machine, the piping system has an equal number of pipes; if nozzles deliver water and air, the piping system can be doubled. Furthermore, corresponding flow control components are associated with each cooling zone.

[0017] Clearly, this solution is extremely complex to implement and very large in size due to the extended piping system. Furthermore, it is very difficult to manage and requires frequent maintenance intervention due to the large number of components.

[0018] In other known solutions, the piping system includes one pipe for conveying low-pressure refrigerant fluid and another pipe for conveying high-pressure refrigerant fluid. Both pipes supply a valve block located on the cooling unit and are configured to allow passage from low pressure to high pressure and vice versa.

[0019] While this solution allows for the management of large cooling zones using only two feed pipes, it does not allow for control over the flow rate of the fluid delivered by individual nozzles or individual cooling units.

[0020] Therefore, there is a need to improve the secondary cooling device in machines used for continuous casting of metal products in order to overcome at least one of the disadvantages of the prior art.

[0021] One object of the present invention is to provide a secondary cooling device for a machine for continuously casting metal products, wherein the variable supply of cooling water can be achieved in a simple manner, and the device is not bulky and is easy to manage.

[0022] Another object of the present invention is to provide a secondary cooling device in which the piping system for supplying cooling fluid has a limited extension range.

[0023] Another object of the present invention is to provide a secondary cooling device in which the flow regulation component is simple and comprises a limited number of parts.

[0024] Another object of the present invention is to provide a secondary cooling device that requires limited maintenance intervention.

[0025] The applicant has designed, tested and implemented the present invention to overcome the disadvantages of the prior art and to obtain these and other objectives and advantages. Summary of the Invention

[0026] The invention is set forth and characterized in the independent claims. The dependent claims describe other features or variations of the main inventive concept of the invention.

[0027] According to the above objective, a secondary cooling device is provided for a machine for continuously casting metal products, wherein each metal product is cast, contained and guided along a motion axis, the secondary cooling device comprising a plurality of cooling components arranged sequentially one after another along the continuous casting machine.

[0028] Each component as described above includes multiple cooling units, and each cooling unit is provided with one or more nozzles arranged along the axis of motion.

[0029] The cooling units of each component are arranged adjacent to each other to cover a width at least equal to the maximum width of a metal product that can be cast in a continuous casting machine.

[0030] According to one aspect of the invention, each nozzle of each cooling unit includes two or more orifices for delivering refrigerant fluid to the metal product to be cooled. Furthermore, one orifice of a nozzle is associated with a fluid supply line different from the other orifices of the same nozzle.

[0031] The same source holes of different nozzles in the same cooling unit are associated with the same supply line.

[0032] This solution allows for the differentiation and adjustment of the cooling fluid flow rate in various regions of a cast product, particularly across its width, simply by activating one or more supply lines connected to homogeneous nozzles of different cooling units and components. This adapts the cooling action to the effective width of the cast product and the instantaneous needs that arise. For example, the cooling intensity of the central region of the cast product relative to its transverse regions can be easily distinguished.

[0033] Furthermore, this solution allows for the use of a reduced number of main conduits for supplying fluid, which can be supplied through a single valve assembly, such as a main servo valve that sets a single supply flow rate, and then manages the variation in the delivery rate of the cooling fluid to the casting product by selectively opening / closing the corresponding nozzles of each cooling unit / assembly. Attached Figure Description

[0034] These and other aspects, features, and advantages of the invention will become apparent from the following description of some embodiments given by way of non-limiting examples with reference to the accompanying drawings, in which:

[0035] Figure 1 A metal casting machine for joining products is schematically shown, which includes a secondary cooling device according to an embodiment described herein;

[0036] Figure 2 A cooling assembly with eight cooling units is schematically shown;

[0037] Figure 3 The possible structure of the secondary cooling device according to the embodiments described herein is schematically illustrated;

[0038] Figure 4 The diagram schematically illustrates another possible structure of the secondary cooling device according to the embodiments described herein;

[0039] Figure 5 The nozzle is shown schematically, with the delivery orifice visible.

[0040] Figures 5a-5d It shows Figure 5 Possible variations of the conveying orifice; and

[0041] Figure 6 It is shown Figure 2 The flow rate-pressure curve of the operating mode of the cooling component, for example, is shown in the figure. Figure 5b or Figure 5c The nozzle in the middle.

[0042] For ease of understanding, the same reference numerals are used to identify the same common elements in the figures where possible. It should be understood that elements and features of one embodiment can be readily incorporated into other embodiments without further explanation. Detailed Implementation

[0043] Reference will now be made in detail to various embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each embodiment is provided to illustrate the invention and should not be construed as limiting the invention. For example, one or more features shown or described, even if they are part of one embodiment, may be changed or adopted in other embodiments, or combined with other embodiments to produce other embodiments. It should be understood that the invention should include all such possible modifications and variations.

[0044] Before describing these embodiments, it must be clarified that the application of this specification is not limited to the details of the construction and arrangement of the components as described below using the accompanying drawings. This specification may provide other embodiments and may be obtained or implemented in various other ways. It must also be clarified that the wording and terminology used herein are for descriptive purposes only and should not be considered limiting.

[0045] Reference Figure 1 The described embodiments relate to a machine for continuously casting metal products, generally designated by reference numeral 10. The machine 10 is configured to continuously cast metal products P, for example, in the form of large billets, billets, or slabs, or other forms known in the art.

[0046] During the casting process, the metal product P is first cooled by the primary cooling device 11, and then cooled by the secondary cooling device 12.

[0047] The machine 10 includes a casting tray 26 and a mold or crystallizer 14, the casting tray 26 being able to receive liquid metal contained in a ladle 13, the liquid metal passing through the mold or crystallizer 14.

[0048] The primary cooling device 11 is directly associated with the crystallizer 14, while the secondary cooling device 12 is located downstream of the crystallizer 14.

[0049] The secondary cooling device 12 includes a roller conveyor 15 configured to guide and contain the metal product P at the outlet of the crystallizer 14 and remove heat from the metal product P, for example, by means of a radiator and a conductor.

[0050] The roller conveyor 15 is capable of supporting and moving the cast metal product P along the motion axis X, which can be curved, straight, or partially curved and partially straight.

[0051] The roller conveyor 15 may include a plurality of rollers 16, which may be appropriately spaced from each other and whose axes of rotation are parallel to each other and orthogonal to the axis of motion X. The rollers 16 are configured to guide the metal product P along the casting line to the extraction area.

[0052] For this purpose, the axis of rotation of the roller 16 located above the metal product P can be located on a plane parallel to and spaced apart from the plane containing the axis of rotation of the roller 16 located below the metal product P. In this way, the roller 16 defines a passage and a traction channel within which the cast metal product advances.

[0053] In a possible embodiment, roller 16 may also be arranged laterally relative to product P so as to guide product P along the side as well.

[0054] In this particular case, the secondary cooling device 12 includes a plurality of cooling components G, which are arranged sequentially along the continuous casting machine 10.

[0055] Special Reference Figure 2-4 In this configuration, each cooling assembly G may include multiple cooling units 17, and each cooling unit 17 is provided with one or more nozzles 18 arranged along the motion axis X.

[0056] The cooling units 17 are adjacent to each other to cover a width that is at least equal to the maximum width of the metal product P that can be cast into the machine 10.

[0057] Each cooling unit 17 is capable of delivering at least one refrigerant fluid L at a defined flow rate to a specific area of ​​the metal product P. The cooling unit 17 may be associated with a roller conveyor 15 to cooperate with the roller conveyor 15 in cooling the metal product P during transport.

[0058] According to some embodiments, the cooling unit 17 may be arranged along a vertical segment and also along a curved segment, and may be arranged on a horizontal segment of the casting line, and may act on the bottom and top of the metal product P. Optionally, the cooling unit 17 may also act laterally relative to the metal product P.

[0059] Cooling units 17 can determine the same cooling pattern for the upper and lower surfaces of the metal product P according to the required cooling curve, or they can determine different and independent cooling patterns.

[0060] According to some embodiments, each of the nozzles 18 in each cooling unit 17 includes two or more holes 19 for delivering refrigerant fluid L to the metal product P to be cooled, such as... Figure 2-5 As shown.

[0061] Specifically, one orifice 19 of a nozzle 18 is associated with a supply line 24, distinct from other orifices 19 of the same nozzle 18, such as... Figure 5 As shown. Additionally, please refer to the following: Figure 2-3 The same source holes 19 of different nozzles 18 in the same cooling unit 17 are connected to the same supply line 24.

[0062] Furthermore, the same source holes 19 of the cooling units 17 of different components G can be connected to the same supply line 24.

[0063] In this specification and below, the term “homogeneous” is used to refer to hole 19, meaning that a hole 19 of a nozzle 18 corresponds by geometric analogy (e.g., by position) to a hole 19 of another nozzle 18 of another cooling unit 17 and / or a different cooling assembly G.

[0064] According to some embodiments, each cooling unit 17 preferably has two to seven nozzles 18, which can be arranged along the longitudinal axis Y of the unfolded cooling unit 17, such as... Figure 2 As shown.

[0065] The nozzles 18 of the cooling unit 17 may preferably be aligned along its longitudinal axis Y, or may be alternately arranged on one side and the other side relative to the longitudinal axis Y to define a checkerboard configuration, or according to other possible configurations.

[0066] The cooling unit 17 is configured such that the nozzles 18 are distributed in a suitable manner along the direction of the motion axis X and in a direction transverse to the motion axis X, so as to ensure cooling of any area of ​​the metal product P.

[0067] According to some embodiments, the orifices 19 of the same nozzle 18 are supplied independently of each other by opening or closing one or more supply lines 24 associated with the nozzle 18. The supply lines 24 may be configured as pipes of variable length and have any cross-section, each section communicating directly or via another branch with the orifice 19 of the nozzle 18. The supply lines 24 may also have structural functions supporting the nozzle 18.

[0068] The orifice 19 of the same nozzle 18 can have the same outlet cross-section area, such as... Figures 5a-5c As shown; or with different outlet cross-sections, such as Figure 5d As shown. The shape of the outlet cross section of each orifice 19 determines the shape of the jet of refrigerant fluid L, such as a blade shape or a cone shape, or other shapes that are considered suitable for cooling metal products P.

[0069] refer to Figure 2-4The secondary cooling device 12 also includes a supply circuit 21 for supplying cooling units 17. The supply circuit 21 includes a plurality of valve assemblies 22, each valve assembly 22 being associated with a corresponding cooling unit 17. Each valve assembly 22 includes at least one valve 22a for each orifice 19 of different nozzles 18 of the same cooling unit 17.

[0070] Supply circuit 21 is connected to at least one main supply conduit 25, which is configured to fluidly connect a device 23 for pumping refrigerant fluid L to valve assembly 22. Specifically, each main supply conduit 25 includes a single throttling device 30 configured to control and, possibly, regulate the flow rate of refrigerant fluid L in at least one main supply conduit 25 toward cooling unit 17.

[0071] Here and below, “main supply conduit 25” means that one or more pipes are connected to the pumping device 23 on one side and to the valve assembly 22 on the other side, and the valve assembly 22 is then connected to a separate supply line 24.

[0072] Each valve 22a is connected to the same orifice 19 of the nozzle 18 of the corresponding cooling unit 17 via a corresponding supply line 24, and may be connected to different cooling units 17 of different cooling assemblies G.

[0073] According to some embodiments, in order to minimize the length of the supply line 24, the valve assembly 22 can be directly attached to the appropriate cooling unit 17, for example, at the head position.

[0074] Each valve 22a can be an on / off type to allow or block the passage of refrigerant fluid L toward orifice 19.

[0075] According to some embodiments, valve assembly 22 can be advantageously actuated hydraulically or electrically in order to keep electrical components in a safe area away from possible interaction with the refrigerant fluid L.

[0076] In one possible configuration, the orifices 19 of the nozzles 18 all have different outlet cross-sections, and each cooling unit 17 has an activation 2. n There are n possible cooling modes, where the number "2" represents two operating possibilities (on / off), and "n" is the number of orifices 19 included in each nozzle 18. On the other hand, if all orifices 19 have the same outlet cross-section, the possible cooling modes are n+1. Possible intermediate configurations are included in these values.

[0077] The cooling units 17 of the defined cooling assembly G can be started independently of each other, as each of them is controlled by a corresponding valve assembly 22.

[0078] According to some embodiments, the cooling unit 17 of the defined cooling assembly G can be advantageously activated symmetrically with respect to the symmetry center axis of the metal product P in order to define symmetrical and independent cooling areas.

[0079] exist Figure 2 In the illustrative example shown, four cooling zones A, B, C, and D are defined, symmetrical about the central axis of symmetry of the metal product P, which in this case corresponds to the axis of motion X. All nozzles 18 operate at the same pressure, assuming a single flow-controlling device 30 is present to regulate the flow rate. However, by selectively activating a certain number of orifices 19, different flow rates can be obtained across the width and / or length of the transported metal product P, thus resulting in zones with different cooling efficiencies. For example, the following configuration can be achieved:

[0080] -Area A is completely closed (the wet area is narrower than the metal product area P).

[0081] - Zone B provides a low cooling flow rate (edge), opening only the first orifice 19a and / or the second orifice 19b of each nozzle 18 present in Zone B.

[0082] Regions C and D provide high cooling flow rates because they are located at the center of the metal product P; in these regions, all three orifices 19a, 19b, and 19c are open.

[0083] Figure 6 The graph shown illustrates the pressure / flow rate relationship of nozzle 18, for example, in Figure 5b or Figure 5c The three curves refer to the construction of one, two, or three functional holes 19. In this example, two cooling zones (FR zones B and FR zones C and D) have been defined, but theoretically, as many cooling zones as cooling units 17 in the cooling assembly G can be defined.

[0084] According to some embodiments, each cooling component G is autonomously supplied via its own main supply conduit 25, which connects the pumping device 23 to the cooling component G, as shown. Figure 3 As shown.

[0085] According to other embodiments, two or more cooling components G are supplied by the same main supply conduit 25, which connects the pumping device 23 to the cooling component G via corresponding supply lines 24, such as... Figure 4 As shown. This configuration allows the number of main supply conduits 25 to be reduced to a minimum, and thus allows for a simplified construction of the secondary cooling unit 12.

[0086] According to some embodiments, the shut-off device 30 of each main supply conduit 25 may be, for example, a servo valve 31. Additionally, a flow meter and a pressure sensor may also be provided.

[0087] The presence of a single servo valve 31 for controlling the flow rate of the refrigerant fluid L through the main supply conduit 25 allows all nozzles 18 of the cooling unit 17 of that particular cooling assembly G to deliver the refrigerant fluid L at the same pressure. However, as described above, by selectively activating a certain number of orifices 19 by opening valve 22a, the delivery of the same nozzle 18 can be partialized, thereby obtaining different flow rates with different cooling efficiencies.

[0088] According to some embodiments, the secondary cooling device 12 may include a control and command unit 20 in which a mathematical model is implemented, the mathematical model being configured to estimate the surface temperature of the metal product P in a punctual manner. The flow rate of the refrigerant fluid L is changed such that the temperature estimated by the mathematical model corresponds to the desired temperature.

[0089] The secondary cooling device 12 may include a surface temperature detector, which allows verification of the instantaneous temperature on the metal product P.

[0090] According to a possible embodiment, the surface temperature detector can allow feedback control of the flow rate of the refrigerant fluid L. In this case, the surface temperature detector can detect the temperature of a specific area of ​​the metal product P and send a corresponding operating signal to the control and command unit 20 to perform feedback control, thereby limiting the flow rate value of the refrigerant fluid L that the cooling unit 17 must deliver.

[0091] The control and command unit 20 can be configured to receive one or more process operating parameters. These process operating parameters can be selected from the group consisting of: the volumetric flow rate of the metal product P, the temperature detected zone by zone on the metal product P, the chemical composition of the metal product P (or steel grade), the form of the product, or other process parameters considered characteristic.

[0092] The control and command unit 20 is also configured to process and send operation command signals to the device 23 for pumping refrigerant fluid L, and to send operation command signals to the valve 22a of the throttling device 30 and the valve assembly 22 to obtain the desired cooling profile.

[0093] According to some embodiments, the refrigerant fluid L may be water, which can be processed. However, the use of a refrigerant mixture comprising at least a first liquid refrigerant fluid (e.g., water) and at least a second gaseous refrigerant fluid (e.g., air) is not excluded. It is quite obvious that the use of a refrigerant fluid or mixture may determine modifications to the system for regulating the pumping of these fluids.

[0094] Obviously, modifications and / or additions can be made to the secondary cooling device in the machine for continuous casting of metal products described so far without departing from the scope and domain of the present invention.

[0095] It is also clear that although the present invention has been described with reference to some specific embodiments, those skilled in the art will of course be able to obtain many other equivalent forms of secondary cooling devices for machines used in the continuous casting of metal products, which have the features described in the claims, and all of these are therefore within the scope of protection defined therein.

[0096] In the claims, references in parentheses are for ease of reading and should not be considered as limiting factors on the field claimed in a particular claim.

Claims

1. A secondary cooling device (12) in a machine (10) for continuously casting metal products (P), wherein, Each metal product (P) is cast, housed, and guided along the axis of motion (X), and the secondary cooling device (12) includes: - Multiple cooling components (G) are arranged sequentially one after another along the continuous casting machine (10). - Each of the components (G) includes a plurality of cooling units (17), each cooling unit (17) being provided with one or more nozzles (18) arranged along the axis of motion (X). - wherein the cooling units (17) of each component (G) are adjacent to each other to cover a width at least equal to the maximum width of the metal product (P) cast in the continuous casting machine (10), Its features are, - Each nozzle (18) of each cooling unit (17) includes two or more orifices (19) for delivering refrigerant fluid (L) to the metal product (P) to be cooled. One of the two or more holes (19) of the nozzle (18) is associated with a line (24) for supplying refrigerant fluid, and is different from the other holes (19) of the same nozzle (18). - The orifices (19) of different nozzles (18) of the same cooling unit (17) are associated with the same pipeline (24) for supplying refrigerant fluid; Furthermore, the secondary cooling device (12) further includes a supply circuit (21) for supplying the cooling unit (17) and has a plurality of valve assemblies (22), each valve assembly (22) being associated with a corresponding cooling unit (17). The supply circuit (21) is connected to at least one main supply conduit (25), which is configured to fluidly connect a pumping device (23) to the valve assembly (22). The at least one main supply conduit (25) includes a single throttling device (30) configured to control the flow rate of refrigerant fluid (L) flowing toward the cooling unit (17) in the at least one main supply conduit (25).

2. The secondary cooling device as described in claim 1, characterized in that, The orifices (19) of different nozzles (18) of different cooling units (17) and different cooling components (G) are associated with the same pipeline (24) for supplying refrigerant fluid.

3. The secondary cooling device as described in claim 1 or 2, characterized in that, Each valve assembly (22) includes at least one valve (22a) for each of the homologous orifices (19) of different nozzles (18) of the same cooling unit (17).

4. The secondary cooling device as described in claim 1, characterized in that, Each cooling component (G) is autonomously supplied via its own main supply conduit (25), which connects the pumping device (23) to the cooling component (G).

5. The secondary cooling device as described in claim 1, characterized in that, Two or more of the cooling assemblies (G) are supplied by the same main supply conduit (25) that connects the pumping device (23) to the cooling assembly (G).

6. The secondary cooling device as described in claim 1, characterized in that, The flow control device (30) includes a servo valve (31) configured to ensure that the refrigerant fluid (L) flows at the same pressure to the cooling unit (17) of the main supply conduit (25) associated with the servo valve (31).

7. The secondary cooling device as described in claim 1, characterized in that, Each nozzle (18) is determined according to the values ​​included in n + 1 and 2. n Multiple cooling modes are used to start the process, where n is the number of holes (19) in the nozzle (18).

8. The secondary cooling device as described in claim 3, characterized in that, Each valve (22a) is an on / off type.

9. The secondary cooling device as described in claim 1, characterized in that, The cooling units (17) of the defined cooling assembly (G) are activated independently of each other.

10. The secondary cooling device as described in claim 1, characterized in that, The cooling unit (17) of the defined cooling assembly (G) is activated symmetrically with respect to the symmetrical central axis of the metal product (P) in order to define symmetrical and independent cooling areas.

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