Design method of uniform solidification distributor for semi-continuous casting of large aluminum alloy thick plate

Abstract

This invention discloses a design method for a uniform solidification distributor based on semi-continuous casting of large aluminum alloy thick plates. The method utilizes the fluid simulation software Ansys Fluent to establish a flow and heat transfer model integrating the distributor, crystallizer, and molten aluminum within the semi-continuous casting mold. By systematically adjusting the structural and process parameters of the distributor and performing simulation calculations, the flow field distribution, temperature field evolution, and molten pool morphology changes during ingot solidification are accurately obtained. Finally, based on in-depth analysis of these patterns, the optimal parameter scheme for the distributor is optimized to achieve a shallow, flat molten pool and uniform solidification. This design method allows for the design of distributors of different specifications for different ingot sizes, addressing the problems of excessively deep molten pools (V-shaped molten pools) and severely uneven ingot solidification in existing semi-continuous casting processes for large aluminum alloy thick plates.

Description

Technical Field

[0001] This invention belongs to the field of semi-continuous casting technology of aluminum alloys, specifically relating to a design method and a diverter, which is suitable for the semi-continuous casting process of large-size aluminum alloy thick plates and can effectively improve the solidification uniformity of ingots. Background Technology

[0002] To meet the urgent demands for lightweight and performance-enhancing equipment in aerospace, transportation, and other fields, 7-series aluminum alloys, with their low density, high specific strength, excellent corrosion resistance, and good machinability, have become irreplaceable key structural materials. Specifically, in the aerospace field, to improve the structural strength and lifespan of airframes, the manufacturing trend is towards large, integrated components to replace traditional spliced ​​structures. In the transportation field (such as high-speed trains and new energy vehicles), to improve range, lightweight vehicle bodies have created an urgent need for high-strength aluminum alloy sheets. These two trends are jointly driving the development of aluminum alloy materials towards larger sizes and higher quality, thus posing more severe technical challenges to the upstream ingot preparation process. Therefore, as the base material for subsequent processing, the preparation of large, high-quality aluminum alloy ingots is a prerequisite for obtaining high-performance thick plates. How to effectively improve the forming quality of large ingots during the casting process has become a core bottleneck restricting the industrial application of high-end aluminum alloy materials.

[0003] Currently, the mainstream process for producing large aluminum alloy thick plates in industry is direct-chill casting (DC casting). Aluminum alloy plates with a width greater than 1500 mm and a thickness exceeding 25 mm are generally defined as large aluminum alloy thick plates. With the continuous increase in ingot cross-sectional dimensions, the difficulty of controlling the flow field and temperature field during the casting process increases significantly, leading to a series of challenging metallurgical quality problems. On the one hand, this directly results in the difficulty of maintaining an ideal shallow and flat molten pool shape: the cooling rate at the center of the ingot decreases sharply, causing a significant increase in the depth of the molten pool, and the bottom contour of the molten pool changes from shallow and flat to a deep concave V-shape, with a significant expansion of the mushy area. On the other hand, regarding the uniform solidification of the ingot, excessive temperature gradients and turbulent jets directly disrupt the uniformity of the crystalline structure. From a macroscopic segregation perspective, an unreasonable high-speed jet will strongly erode the fragile dendritic framework, forcing the solute-rich intergranular liquid to migrate over a large area, resulting in severe negative segregation or positive segregation at the center. From a microscopic perspective, the huge difference in undercooling across the cross-section makes it impossible for grain nucleation and growth rates to be synchronized, easily causing the ingot to exhibit a microstructure of "fine grains at the edges and coarse grains at the center." These solidification inhomogeneities severely weaken the internal density and mechanical property consistency of large aluminum alloy thick plates, greatly restricting the yield and service reliability of high-end aluminum materials.

[0004] The manifold in the casting process is a key component connecting the runner and the crystallizer. Its main function is to introduce the molten metal into the crystallizer cavity at a specific flow rate and direction. During this process, the manifold must both evenly distribute the molten metal to the far end of the crystallizer, avoiding high-speed jets in the central area and stagnant flow at the edges, and also provide guiding and buffering functions to weaken jet impact, prevent excessive molten pool depth, and promote uniform temperature. For commonly used manifolds in existing technology, see [link to relevant documentation]. Figure 1 Typically, a porous structure is used, without considering the matching relationship between the size and shape of the various diversion holes. In this case, when the melt flows out of the diverter, it is difficult to effectively balance the flow velocity between the central and edge regions, resulting in an unreasonable flow field distribution. This, in turn, affects the heat transfer process of the melt within the crystallizer, ultimately restricting the uniformity of ingot solidification. Especially for the semi-continuous casting process of large aluminum alloy thick plates, the diverter is even less able to solve the defect of uneven ingot solidification, leading to unstable product quality and even safety hazards.

[0005] In summary, existing flow dividers have insufficient flow distribution capacity in the semi-continuous casting of large aluminum alloy thick plates. On the one hand, they cause the molten pool to exhibit a V-shaped morphology, drastically increasing the internal stress and hot cracking risk in the mushy zone; on the other hand, they severely exacerbate the uneven solidification of the ingot. Furthermore, existing flow distribution methods struggle to stably transport heat to the far end of the crystallizer, resulting in a significant temperature gradient between the center and edges of the cross-section. Based on this, this invention proposes a design method and flow divider based on a uniform solidification flow divider for semi-continuous casting of large aluminum alloy thick plates. Summary of the Invention

[0006] To address the problems of excessively deep molten pools (V-shaped molten pools) and severely uneven solidification of ingot cross-sections in existing large aluminum alloy thick plate semi-continuous casting processes, this invention provides a design method for a uniform solidification distributor based on semi-continuous casting of large aluminum alloy thick plates, especially for a distributor used for uniform solidification of 2000 mm × 500 mm large thick plates.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A design method for a uniform solidification distributor based on a large, semi-continuously cast aluminum alloy thick plate includes the following steps:

[0009] S1. A mathematical model of the flow and heat transfer within a large-scale aluminum alloy thick-plate semi-continuous casting crystallizer, integrating the distributor, crystallizer, and molten aluminum, was established using fluid simulation software (Ansys Fluent in this invention). The model considers the contact interfaces and relative positions of the distributor, crystallizer, and molten aluminum. Specifically, a fluid-solid coupling interface exists between the distributor and the molten aluminum, and a heat transfer boundary exists between the crystallizer and the molten aluminum. Geometric topological relationships were established based on the actual semi-continuous casting process to accurately describe the melt flow, heat transfer, and solidification behavior. Finally, the optimal combination of structural and process parameters of the distributor was determined using orthogonal experimental design and numerical simulation methods.

[0010] S2. By adjusting the structural and process parameters of the distributor and performing simulation calculations using the established mathematical model, a numerical calculation method based on the finite volume method is adopted. The calculation process uses the standard k-ε turbulence model based on the standard wall function, and the energy model and solidification model are enabled: in the solidification model, the casting speed is set, and the parameters of the mushy region are set to 1×10. 8 The transient calculation time step was set to 0.001 s, and the number of time steps was set to 300,000. The turbulence equation was solved using the first-order upwind SIMPLEC algorithm built into Fluent, while the continuity equation and energy equation were solved using the second-order upwind algorithm. This can accurately obtain the flow field distribution, temperature field evolution, and molten pool morphology changes during the ingot solidification process.

[0011] S3. Based on the in-depth analysis of the above results, optimize the optimal parameter scheme of the distributor to achieve the goal of shallow and flat molten pool and uniform solidification. The method for optimizing the shallow and flat molten pool is as follows: using the molten pool depth, the flatness of the molten pool profile, and the longitudinal and circumferential temperature distribution as evaluation indicators, by analyzing the numerical simulation results under different combinations of distributor structural parameters and process parameters, prioritize the selection of parameter ranges that can reduce the molten pool depth, reduce the curvature of the liquid cavity, and make the solidification front advance uniformly on the cross section; determine the distributor parameter scheme that minimizes the molten pool depth and optimizes the uniformity of the circumferential temperature field.

[0012] Furthermore, step S1 involves meshing the model, wherein the surface mesh uses a sparse-dense grid with a size of 3-5 mm, and the volume mesh has a size of 6 mm; this mesh size ensures high computational accuracy and high computational efficiency.

[0013] Furthermore, the principle for determining the structural parameters of the distributor is as follows: by directionally transporting the high-temperature melt to the far edge of the crystallizer, the impact intensity of the central jet is effectively attenuated, and the impact depth is reduced, so that the wide-face shape of the molten pool changes from the traditional V-shape to a flat, shallow U-shape, thereby achieving uniform solidification of the ingot. Therefore, determining the shape and size of the distributor outlet is the core element for achieving a shallow, flat molten pool and uniform solidification of the ingot.

[0014] The principle for determining the process parameters of the flow divider is as follows: by precisely controlling the impact position of the molten jet, the excessive depth of the molten pool can be effectively suppressed, and the longitudinal and transverse surface temperatures can be kept uniform, ultimately forming a shallow and uniform molten pool shape, thus achieving uniform solidification in the semi-continuous casting of large aluminum alloy thick plates. Therefore, the insertion depth of the flow divider is a key process parameter for controlling the molten pool depth and solidification uniformity.

[0015] Based on the above method, the present invention also provides a distributor based on the uniform solidification of a large aluminum alloy thick plate by semi-continuous casting. The distributor has a rectangular structure, with the top of the distributor fully open as the melt inlet. The bottom of the two wide side walls of the rectangular pool are symmetrically provided with distribution ports, and the bottom of the distributor is symmetrically designed with two circular lower distribution ports.

[0016] Furthermore, for large aluminum alloys with ingot dimensions of 2000 mm × 500 mm (i.e., the cross-sectional width (x-axis) of the billet is 2000 mm and the thickness (y-axis) is 500 mm), the dimensions of the distributor are: 500 mm × 130 mm × 125 mm; among which, the dimensions of the rectangular distributor opening are: 130 mm × 40 mm, and the dimensions of the circular lower distributor opening are: Φ55 mm; the insertion depth of the distributor is 60 mm.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. This invention creatively proposes a design method for a uniform solidification distributor based on semi-continuous casting of large aluminum alloy thick plates. A flow and heat transfer model integrating the distributor, crystallizer, and molten aluminum is established using fluid simulation software (Ansys Fluent). By systematically adjusting the structural and process parameters of the distributor and performing simulation calculations, the flow field distribution, temperature field evolution, and molten pool morphology changes during the ingot solidification process are accurately obtained. Finally, based on in-depth analysis of the above results, the optimal parameter scheme of the distributor is optimized to achieve the goal of a shallow, flat molten pool and uniform solidification.

[0019] 2. The applicant's research found that determining the shape and size of the distributor outlet is the core element for achieving a shallow and flat molten pool and uniform ingot solidification, and the insertion depth of the distributor is a key process parameter for controlling the molten pool depth and solidification uniformity. Different specifications of distributors can be designed for different ingot sizes to solve the problems of excessively deep molten pools (V-shaped molten pools) and severely uneven solidification of the ingot cross-section in existing large aluminum alloy thick plate semi-continuous casting processes.

[0020] 3. For the semi-continuous casting process of large aluminum alloy thick plates (2000 mm × 500 mm), this invention designs a diversion port with "large rectangular holes on the sides as the main component and small circular holes at the bottom as auxiliary components." The diversion port body dimensions are designed to be 500 mm × 130 mm × 125 mm. This size provides ample space for the melt to reside and buffer, effectively suppressing the initial kinetic energy of the melt and significantly reducing the probability of surface fluctuations and eddies. The rectangular holes on both sides directionally transport the high-temperature melt to the edge and corner areas where the cooling rate is rapid, achieving thermal compensation; at the same time, the circular holes at the bottom appropriately limit the concentrated heat input to the slower-dissipating core area of ​​the ingot. This "edge heating and center flow restriction" measure significantly improves the temperature distribution uniformity across the cross-section of the wide, thick plate, thereby greatly reducing the incidence of macroscopic segregation defects.

[0021] The large-sized lateral rectangular flow divider with a height of 40 mm effectively reduces the vertically downward jet kinetic energy, preventing the concentrated jet from damaging the initial solidified shell at the bottom. Simultaneously, the lateral heat flow effectively compensates for heat loss at the edges of the crystallizer, causing the V-shaped molten pool to evolve into a gently sloping U-shaped molten pool. This shallower, flatter molten pool morphology significantly reduces the solidification shrinkage stress and residual thermal stress within the deep, pasty region (solid-liquid two-phase region), suppressing the initiation of central hot cracks in large aluminum alloy thick plates. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an existing symmetrical splitter structure.

[0023] Figure 2 This is a schematic diagram of the structure of the diverter based on the uniform solidification of a large aluminum alloy thick plate by semi-continuous casting, according to Embodiment 1 of the present invention.

[0024] Figure 3 This is an example of an observation point based on a semi-continuously cast large aluminum alloy thick plate according to Embodiment 1 of the present invention;

[0025] Figure 4 This is a comparison of the solidified shell thickness under different lengths of the distributor based on Embodiment 1;

[0026] Figure 5 This is a comparison of the solidified shell thickness under different widths of the distributor based on Embodiment 1;

[0027] Figure 6 The ingot flow field cloud diagram is based on the above embodiment 1;

[0028] Figure 7 This is a cloud map showing the liquid phase fraction distribution at the center of the wide face of the ingot based on Example 1.

[0029] Figure 8 This is a temperature field cloud map of the center of the wide face of the ingot based on Embodiment 1;

[0030] Figure 9 This is a cloud map showing the liquid phase fraction distribution at the center of the narrow face of the ingot based on Example 1.

[0031] Figure 10 This is a temperature field cloud map of the center of the narrow face of the ingot based on Embodiment 1;

[0032] The diagram shows the following labels: 1 – upper inlet; 2 – rectangular side branch outlet; 3 – shell; 4 – circular lower branch outlet. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0034] The applicant's research found that the structural parameters (shape and size) and process parameters (insertion depth) of the manifold are key factors affecting the uniform solidification of large, thick aluminum alloy plates in semi-continuous casting. For the ingot dimensions, designing reasonable parameters can effectively suppress metallurgical defects such as macroscopic segregation, porosity, gas pores, and coarse grains during the casting process, reduce the risk of subsequent cracking, and ensure the forming quality of large, thick aluminum alloy plates. This invention combines mathematical simulation calculations and systematically analyzes different working conditions to obtain the distribution patterns of the flow field and temperature field during ingot solidification in the crystallizer, as well as the evolution characteristics of the molten pool shape. Further research explores the influence of the manifold outlet shape and structural parameters on the aforementioned flow field, temperature field, and molten pool shape. Finally, based on optimal working conditions, an optimized design scheme for the manifold used in semi-continuous casting of large aluminum alloy thick plates is determined.

[0035] This invention provides a design method for a uniform solidification distributor based on a large, semi-continuously cast aluminum alloy thick plate, comprising the following steps:

[0036] S1. Ansys Fluent fluid simulation software was used to establish a flow and heat transfer model of the internal distributor, crystallizer and molten aluminum in a large aluminum alloy thick plate semi-continuous casting crystallizer. The model fully considers the contact interface and relative position relationship between the three, and establishes geometric topological association based on the actual semi-continuous casting process to achieve an accurate description of melt flow, heat transfer and solidification behavior.

[0037] S2. By adjusting the structural and process parameters of the distributor and performing simulation calculations using the established mathematical model, a numerical calculation method based on the finite volume method is adopted. The calculation process uses the standard k-ε turbulence model based on the standard wall function, and the energy model and solidification model are enabled: in the solidification model, the casting speed is set, and the parameters of the mushy region are set to 1×10. 8The transient calculation time step was set to 0.001 s, and the number of time steps was set to 300,000. The turbulence equation was solved using the first-order upwind SIMPLEC algorithm built into Fluent, while the continuity equation and energy equation were solved using the second-order upwind algorithm. This can accurately obtain the flow field distribution, temperature field evolution, and molten pool morphology changes during the ingot solidification process.

[0038] S3. Based on the in-depth analysis of the above-mentioned patterns, optimize the optimal parameter scheme of the manifold to achieve the goals of shallow and flat molten pool and uniform solidification. The method for optimizing the shallow and flat molten pool is as follows: using the molten pool depth, the flatness of the molten pool profile, and the longitudinal and circumferential temperature distribution as evaluation indicators, by comparing and analyzing the numerical simulation results under different combinations of manifold structural parameters and process parameters, prioritize the selection of parameter ranges that can reduce the molten pool depth, reduce the curvature of the liquid cavity, and make the solidification front advance uniformly in the cross section; determine the manifold parameter scheme that minimizes the molten pool depth and optimizes the uniformity of the circumferential temperature field.

[0039] Among them, the structural parameters of the distributor are as follows: by directionally transporting the high-temperature melt to the far edge of the crystallizer, the impact intensity of the central jet is effectively attenuated, and the impact depth is reduced, so that the molten pool shape changes from the traditional deep V-shape to a flat shallow U-shape, thereby achieving uniform solidification of the ingot. Therefore, determining the shape and size of the distributor outlet is the core element to achieve a shallow and flat molten pool and uniform solidification of the ingot.

[0040] The flow divider process parameters: By precisely controlling the impact position of the molten jet, excessive depth of the molten pool can be effectively suppressed, ultimately forming a shallow and uniform molten pool shape, achieving uniform solidification of large aluminum alloy thick plates. Therefore, the insertion depth of the flow divider is a key process parameter for controlling the molten pool depth and solidification uniformity.

[0041] Based on the above design methods and principles, Figure 2 In the structural design of the distributor shown, adjustable structural parameters are set in the geometric modeling stage of step S1, including the shape and size of the splitter orifice. Using the above structural variables as the object, combined with process parameters (insertion depth), multi-condition comparative simulation is performed. The optimal distributor structure and process parameters are determined using molten pool depth, molten pool contour flatness, and circumferential temperature difference as evaluation indicators.

[0042] Example 1

[0043] A design method for a uniform solidification distributor based on a large, semi-continuously cast aluminum alloy thick plate includes the following steps:

[0044] S1. Establish a three-dimensional geometric model of the internal distributor, crystallizer and aluminum liquid in a large aluminum alloy thick plate semi-continuous casting crystallizer, and mesh the model. The surface mesh adopts a sparse mesh with a size of 3~5 mm, and the volume mesh size is 6 mm. This mesh size can ensure high calculation accuracy and high calculation efficiency.

[0045] S2. Import the mesh model obtained in step S1 into the fluid simulation software Ansys Fluent. By setting the physical property parameters and boundary conditions, the semi-continuous casting process of aluminum alloy can be simulated, and the flow field and temperature field distribution characteristics of the ingot in the longitudinal and circumferential directions can be obtained.

[0046] S3. Design the length and width of the distributor body. Five length options were set (400 mm, 450 mm, 500 mm, 550 mm, 600 mm), and five width options were set (100 mm, 110 mm, 120 mm, 130 mm, 150 mm). A full-factor experimental method was used, resulting in 25 design schemes. Simulation calculations were performed, repeating steps S1-S2, to obtain the dynamic laws of flow field distribution, temperature field evolution, and molten pool morphology during ingot solidification under different parameters, and based on this, the optimal distributor length and width were determined.

[0047] Reference Figure 3 Observation points were set at different locations on the ingot to measure the thickness of the solidified shell at the crystallizer outlet. Figure 4 and Figure 5 It can be seen that the solidified shell thickness distribution is most uniform when the size is set to 500 mm × 130 mm. When the distributor length is 400 mm, the thickness distribution is also relatively uniform, but the thickness value is too small, which may cause leakage risk in subsequent processes.

[0048] S4. Based on the optimal length and width determined in S3, an orthogonal experimental design was used to select five parameters as experimental factors: the shape of the splitter's side outlet, the shape of the lower outlet, the dimensions of the two outlets, and the insertion depth of the splitter. Each factor had three levels, as shown in Table 1. L18(3) was selected as the experimental factor. 7 The experiment was designed using an orthogonal array, as detailed in Table 2. Simulation calculations were performed sequentially according to the orthogonal experimental scheme, repeating steps S1 to S2, to obtain the flow field distribution, temperature field evolution, and molten pool morphology changes during the ingot solidification process under different parameter combinations.

[0049]

[0050]

[0051] S5. Based on the in-depth analysis of the above results, the optimal parameter scheme of the manifold is optimized to achieve the goals of a shallow, flat molten pool and uniform solidification. The method for optimizing the shallow, flat molten pool is as follows: using the molten pool depth, the flatness of the molten pool profile, and the longitudinal and circumferential temperature distribution as evaluation indicators, the numerical simulation results under different combinations of manifold structural parameters and process parameters are compared and analyzed to determine the manifold parameter scheme that minimizes the molten pool depth and optimizes the circumferential temperature field uniformity. Through the above design method, a manifold based on the uniform solidification of a large, thick aluminum alloy plate cast in a semi-continuous casting process is obtained.

[0052] See Figure 2 A flow divider based on the uniform solidification of a large aluminum alloy thick plate by semi-continuous casting is obtained by the above method. It has a rectangular structure. The top of the flow divider is fully open as the melt inlet 1. The bottom of the two wide side walls of the rectangular pool is symmetrically provided with flow divider ports 2. The bottom of the flow divider is symmetrically designed with two circular lower flow divider ports 4, where 3 is a side plate in the length direction.

[0053] For a large aluminum alloy plate with an ingot size of 2000 mm × 500 mm, the dimensions of the diverter are designed as follows: 500 mm × 130 mm × 125 mm; among which, the dimensions of the rectangular diverter 2 are 130 mm × 40 mm, the dimensions of the circular lower diverter 4 are Φ55 mm, and the insertion depth is set to 60 mm.

[0054] See Figure 6 The image shows the flow field cloud diagram of the ingot using the distributor of Example 1. It can be seen that during casting, the molten material enters the distributor vertically downwards through inlet 1. At this point, the fluid has high vertical kinetic and potential energy, a high velocity, and is in a highly turbulent state. The molten material flows downwards, first impacting the distributor, forcing the high-speed downward vertical stream to radiate outwards along the bottom surface. During this process, the intense vertical kinetic energy of the molten material is effectively reduced and converted into static pressure energy, causing the flow pattern to gradually change from intense turbulence at the inlet to stable laminar flow inside the cavity. Subsequently, most of the molten material flows horizontally out through outlet 2 designed on the side wall of the distributor under the action of static pressure difference, overcoming the cross-sectional resistance of the large-sized ingot and directionally transporting the molten material to the narrow face and corner cold zone of the crystallizer. The remaining molten material flows downwards through bottom outlet 4. Some of the molten material may roll upwards, forming an internal circulation, using the fluid's own internal friction to dissipate kinetic energy. At this time, the molten material velocity is significantly reduced, and the intense vertical impact force is neutralized. The embodiment described above alters the original flow trajectory of the melt through a flow divider, ultimately creating a flow field pattern within the crystallizer that is dominated by horizontal radial thermal diffusion and supplemented by vertical downward feeding.

[0055] like Figures 7 to 10 As shown, the simulation results of thermal flux coupling within a semi-continuous casting crystallizer for large aluminum alloy thick plates are presented, using optimal structure and process parameters. Among them, Figure 7 and Figure 8 These respectively reflect the distribution law of liquid phase fraction and temperature field cloud map in the width direction of the ingot; Figure 9 and Figure 10 These respectively reflect the liquid phase fraction and temperature field distribution patterns along the ingot thickness direction. When the aforementioned distributor structure and process parameters are used, it can be clearly observed that the distributor effectively reduces the initial velocity of the melt jet, directionally transporting the high-enthalpy melt to the corner region of the crystallizer in a stable laminar flow state, resulting in a more uniform temperature distribution on both the wide and narrow faces of the ingot. Figure 8 and Figure 10 As shown. Furthermore, the originally easily occurring V-shaped cavitation evolved into... Figure 7 and Figure 9 The image shows a flat and wide shallow U-shaped liquid cavity. Furthermore, Figure 7 The localized moderate concavity feature shown in the liquid phase fraction cloud diagram further confirms that the circular diversion orifice precisely retains an appropriate amount of vertical heat input. This "strong lateral spreading and weak bottom supplementation" flow distribution pattern avoids the risk of hot cracking caused by excessively deep molten pools, and ultimately achieves good shallow and flat molten pool control and uniform solidification results on a large cross-section of 2000 mm × 500 mm.

[0056] In summary, the diverter can reduce the depth of the molten pool, make the shape of the molten pool flatter, effectively improve the uniformity of the ingot during the solidification process, and thus improve the internal quality of large aluminum alloy thick plates.

[0057] Example 2

[0058] The above design method yields a flow divider for uniform solidification of large aluminum alloy thick plates in semi-continuous casting. Flow dividers of different specifications can be designed to address the problems of excessively deep molten pools (V-shaped molten pools) and severely uneven solidification of the ingot cross-section in existing semi-continuous casting processes for large aluminum alloy thick plates.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A design method for a uniform solidification distributor for large, thick aluminum alloy plates produced by semi-continuous casting, comprising the following steps: S1. A mathematical model of the flow and heat transfer of the internal distributor, crystallizer and molten aluminum in a large aluminum alloy thick plate semi-continuous casting crystallizer was established using fluid simulation software. S2. By adjusting the structural and process parameters of the distributor and performing simulation calculations using the established mathematical model, a numerical calculation method based on the finite volume method is adopted. The calculation process uses the standard k-ε turbulence model based on the standard wall function, and the energy model and solidification model are enabled: in the solidification model, the casting speed is set, and the parameters of the mushy region are set to 1×10. 8 The transient calculation time step was set to 0.001 s, and the number of time steps was set to 300,000. The turbulence equation was solved using the first-order upwind SIMPLEC algorithm built into Fluent, while the continuity equation and energy equation were solved using the second-order upwind algorithm. This can accurately obtain the flow field distribution, temperature field evolution, and molten pool morphology changes during the ingot solidification process. S3. Based on the in-depth analysis of the above simulation results, the optimal parameter scheme of the manifold to achieve a shallow and flat molten pool and uniform solidification is established. Specifically, the molten pool depth, molten pool profile, and longitudinal and circumferential surface temperature distribution are used as evaluation indicators. By comparing the numerical simulation results under different combinations of manifold structure and process parameters, parameters that can effectively reduce the molten pool depth and make the solidification front advance smoothly in the cross section are selected. Finally, the manifold parameter scheme that makes the molten pool shape tend to be shallow and flat and has the best circumferential and longitudinal surface temperature uniformity is determined.

2. The design method of the uniform solidification diverter based on the semi-continuous casting large aluminum alloy thick plate according to claim 1, characterized in that, The fluid simulation software can be Ansys Fluent or COMSOL; this study uses Ansys Fluent.

3. The design method for a uniform solidification distributor based on a semi-continuous casting large aluminum alloy thick plate according to claim 1, characterized in that, In step S1, the distributor and the molten aluminum have a fluid-solid coupling interface, and the crystallizer and the molten aluminum have a heat transfer boundary, thereby realizing the control of melt flow, heat transfer and solidification behavior; finally, based on orthogonal experimental design and numerical simulation, the optimal combination of structural parameters and process parameters of the distributor is determined.

4. The design method of the uniform solidification diverter based on the semi-continuous casting large aluminum alloy thick plate according to claim 1, characterized in that, In step S1, the model is meshed, with the surface mesh using a sparse-dense grid with a size of 3-5 mm, and the volume mesh having a size of 6 mm; this mesh size ensures high computational accuracy and high computational efficiency.

5. The design method of the uniform solidification diverter based on the semi-continuous casting large aluminum alloy thick plate according to claim 1, characterized in that, The principle for determining the structural parameters of the distributor is as follows: by directionally transporting the high-temperature melt to the far edge of the crystallizer, the impact intensity of the central jet is effectively attenuated, the impact depth is reduced, and the wide surface shape of the molten pool is changed from the traditional V-shape to a flat shallow U-shape. The principle for determining the process parameters of the distributor is as follows: by precisely controlling the impact position of the melt jet, the excessive depth of the molten pool can be effectively suppressed, the longitudinal and transverse surface temperatures can be kept uniform, and a shallow and uniform molten pool shape can be formed, thereby achieving uniform solidification of large aluminum alloy thick plates in semi-continuous casting.

6. The design method of the uniform solidification diverter based on a semi-continuous casting large aluminum alloy thick plate according to claim 1, characterized in that, The model establishes a three-dimensional geometric structure with a width of a = 1800~2040 mm and a thickness of b = 400~520 mm.

7. A diverter based on the uniform solidification of a large, thick aluminum alloy plate cast in a semi-continuous casting process, characterized in that... The design method described in any one of claims 1 to 6 is used to obtain a distributor with a rectangular structure. The top of the distributor is fully open as the melt inlet. The bottom of the two wide side walls of the rectangular pool is symmetrically provided with distributor ports. The bottom of the distributor is symmetrically designed with two circular lower distributor ports.

8. The distributor based on the uniform solidification of a large, thick aluminum alloy plate by semi-continuous casting according to claim 7, characterized in that, For large aluminum alloy ingots with dimensions of 2000 mm × 500 mm, the dimensions of the manifold are: 500 mm × 130 mm × 125 mm; the dimensions of the rectangular manifold opening are: 130 mm × 40 mm, and the dimensions of the circular lower manifold opening are: Φ55 mm; the insertion depth of the manifold is 60 mm, which is the depth to which the bottom of the manifold is immersed in the molten pool.

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