Method for determining hot taper of crystallizer copper tube

Abstract

The present application relates to a kind of crystallizer copper tube hot taper determination method, belong to metallurgical continuous casting technical field.The method includes the following steps:1) establish crystallizer copper tube cold taper layer piece method model, calculate the cold taper of crystallizer copper tube;2) the heat flow density distribution law of different water cooling structure crystallizer copper tube in height direction and circumferential is obtained by thermal coupling mathematical model simulation calculation;3) the three-dimensional thermal deformation of different water cooling structure crystallizer copper tube is obtained by three-dimensional thermal deformation model simulation calculation;4) the cold taper and the three-dimensional thermal deformation of different water cooling structure crystallizer copper tube are superimposed, and the hot taper of respective water cooling structure crystallizer copper tube is obtained.According to the present application, the cold taper curve considering steel grade and the change of drawing speed and the three-dimensional thermal deformation of different water cooling structure crystallizer copper tube can be obtained, the hot taper curve of different water cooling structure crystallizer copper tube is obtained, more in line with the solidification shrinkage of casting blank, so that the surface quality of casting blank is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical continuous casting technology and relates to a method for determining the hot taper of a copper tube in a crystallizer. Background Technology

[0002] The taper curve of the crystallizer copper tube refers to the tapered curve formed by the inner surface of the crystallizer copper tube, which is wider at the top and narrower at the bottom, to ensure good contact between the inner surface of the crystallizer copper tube and the cast billet during solidification shrinkage. To accurately design the inner cavity shape of the crystallizer copper tube, different scholars have proposed their own taper curves, including parabolic taper curves, hyperbolic taper curves, and power function taper curves. However, some problems still exist in this area, mainly:

[0003] (1) The existing technology mainly describes the inner taper curve of the copper tube in the crystallizer under cold conditions. However, the copper tube will undergo thermal deformation due to high temperature load during use. After deformation, the inner taper curve of the copper tube will be different from the initial design value.

[0004] (2) The water-cooling structure of the crystallizer copper tubes has evolved from the common planar water slot type to the water tank type and the round hole type. Due to the different structural forms of the copper tubes through which cooling water flows, the thermal deformation of the crystallizer copper tubes with different water-cooling structures is also different under high-temperature load. It is obviously unreasonable to use the same taper curve if the water-cooling structures of the crystallizer copper tubes are different.

[0005] (3) The most common method for designing the taper of the copper tube in a crystallizer is to obtain the total taper of the crystallizer based on the total shrinkage of the molten steel in the crystallizer, and then calculate the parabolic taper distribution of the crystallizer based on the total taper. However, this method cannot reflect the changes in taper with steel grade and casting speed, and has certain limitations.

[0006] Therefore, the design of the actual taper curves for copper tubes in crystallizers with different water-cooled structures should be based on the cold-state taper curves considering variations in steel grade and casting speed, superimposed with the three-dimensional thermal deformation of each water-cooled structure copper tube—that is, the hot-state taper curves of copper tubes with different water-cooled structures. This approach better reflects the solidification shrinkage of the cast billet, ensuring the surface quality of the billet. Summary of the Invention

[0007] In view of this, the purpose of this invention is to provide a method for determining the hot taper of crystallizer copper tubes, guiding the design of the actual taper curves of crystallizer copper tubes with different water-cooled structures.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for determining the hot taper of a crystallizer copper tube includes the following steps:

[0010] S1 establishes a cold taper layer method model for the copper tube of the crystallizer, and calculates the cold taper of the copper tube of the crystallizer based on the steel composition, billet cross-sectional dimensions and casting speed;

[0011] S2 establishes a thermo-mechanical coupling mathematical model of copper tubes in crystallizers with different water-cooled structures. The cold taper obtained in step S1 is used as the input condition. The heat flux density distribution law of copper tubes in crystallizers with different water-cooled structures in the height direction and circumferential direction is obtained through simulation calculation.

[0012] S3 establishes a three-dimensional thermal deformation model of the copper tubes of the crystallizer with different water-cooled structures. The heat flux density obtained in step S2 is used as the input condition for the copper tubes of the crystallizer with different water-cooled structures. The three-dimensional thermal deformation of the copper tubes of the crystallizer with different water-cooled structures is obtained through simulation calculation.

[0013] S4 superimposes the cold taper obtained in step S1 and the three-dimensional thermal deformation of the copper tubes of different water-cooled crystallizer structures obtained in step S3 to obtain the hot taper of the copper tubes of each water-cooled crystallizer structure.

[0014] Optionally, the crystallizer copper tubes are classified into planar water-slit type crystallizer copper tubes, water-trough type crystallizer copper tubes, and round hole type crystallizer copper tubes according to different water-cooling structure types.

[0015] Optionally, for crystallizer copper tubes with different water-cooling structures, the final design taper is the hot taper of the crystallizer copper tube with its water-cooling structure.

[0016] Optionally, the basic idea of ​​the "layer method calculation model" in step S1 is as follows: divide the billet in the crystallizer into several layers from the top to the bottom, with each layer having a thickness of h. Then, based on the solidification shrinkage characteristics of the steel grade, design a separate taper for each layer.

[0017] Optionally, the basic equations can be established for element i:

[0018]

[0019] In the formula, a i ,b i ,a i+1 ,b i+1 Δh represents the width and narrowness dimensions of the upper and lower layers of element i, respectively, in mm; Δh is the height of element i; Δv is the height of element i. i The difference in volume between element i and element i-1, in mm. 3 e1 represents the volume change rate of molten steel during solidification shrinkage, in %; e1 represents the volume fraction of δ-Fe; e2 represents the solid-state phase change shrinkage rate, %; e3 represents the liquid-state shrinkage volume change rate, %.

[0020] The beneficial effects of this invention are as follows:

[0021] (1) The cold taper of the copper tube in the crystallizer can reflect its variation with steel grade and casting speed, which is more in line with the solidification shrinkage characteristics of the billet.

[0022] (2) Under the same continuous casting machine process parameters, the three-dimensional thermal deformation of the crystallizer copper tubes with different water-cooled structures is different under high temperature load, so the actual design taper curves of the crystallizer copper tubes with different water-cooled structures are also different.

[0023] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0025] Figure 1 This is a schematic diagram of the layer-by-layer method model of the present invention;

[0026] Figure 2 This is a schematic diagram of the copper tube of the planar water-slit crystallizer of the present invention;

[0027] Figure 3 This is a schematic diagram of the copper tube of the water tank type crystallizer of the present invention;

[0028] Figure 4 This is a schematic diagram of the copper tube of the circular hole type crystallizer of the present invention;

[0029] Figure 5 This is the actual design taper curve of the copper tubes of the crystallizer in each water-cooled structure of this invention.

[0030] Figure reference numerals: 1. Copper tube for crystallizer; 2. Copper tube for planar water-slot type crystallizer; 3. Copper tube for water-trough type crystallizer; 4. Copper tube for round hole type crystallizer. Detailed Implementation

[0031] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0032] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0033] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0034] Please see Figures 1-5 , Figure 1 This is a schematic diagram of the layer-by-layer method model of the present invention, including the crystallizer copper tube 1. Figure 2 This is a schematic diagram of the copper tube of the planar water-slot crystallizer of the present invention, including the planar water-slot crystallizer copper tube 2. Figure 3 This is a schematic diagram of the copper tube of the water tank type crystallizer of the present invention, including the copper tube 3 of the water tank type crystallizer. Figure 4 This is a schematic diagram of the copper tube of the circular hole type crystallizer of the present invention, including the circular hole type crystallizer copper tube 4. Figure 5 These are the actual design taper curves of the copper tubes of each water-cooled crystallizer in Embodiment 1 of the present invention.

[0035] The method for determining the hot taper of the copper tube 1 in the crystallizer consists of the following steps:

[0036] Step 1: Establish a cold taper layer model of the crystallizer copper tube, and calculate the cold taper of the crystallizer copper tube 1 based on the steel composition, billet cross-sectional dimensions and casting speed.

[0037] The basic idea of ​​the layer method calculation model is to divide the billet in the crystallizer into several layers from the top to the bottom, with each layer having a thickness of Δh. Then, based on the solidification shrinkage characteristics of the steel grade, a separate taper design is carried out for each layer.

[0038] like Figure 1 As shown, the basic equations can be established for element i:

[0039]

[0040] In the formula, a i ,bi ,a i+1 ,b i+1 Δh represents the width and narrowness dimensions of the upper and lower layers of element i, respectively, in mm; Δh is the height of element i; Δv is the height of element i. i The difference in volume between element i and element i-1, in mm. 3 e1 represents the volume change rate of molten steel during solidification shrinkage, in %; e1 represents the volume fraction of δ-Fe; e2 represents the solid-state phase change shrinkage rate, %; e3 represents the liquid-state shrinkage volume change rate, %.

[0041] Step 2: Establish a thermo-mechanical coupling mathematical model for copper tubes of crystallizers with different water-cooled structures. Using the cold taper obtained in Step 1 as the input condition, the heat flux density distribution law of copper tubes of crystallizers with different water-cooled structures in the height and circumferential directions is obtained through simulation calculation.

[0042] Step 3: Establish three-dimensional thermal deformation models of copper tubes in crystallizers with different water-cooled structures. Use the heat flux density obtained in Step 2 as the input condition for each copper tube in the crystallizer with different water-cooled structures. The three-dimensional thermal deformation of copper tubes in crystallizers with different water-cooled structures is obtained through simulation calculation.

[0043] Step 4: Superimpose the cold taper obtained in Step 1 and the three-dimensional thermal deformation of the copper tubes of different water-cooled crystallizer structures obtained in Step 3 to obtain the hot taper of the copper tubes of each water-cooled crystallizer structure.

[0044] like Figures 2-4 As shown, the crystallizer copper tube 1 can be divided into planar water-slit type crystallizer copper tube 2, water tank type crystallizer copper tube 3 and round hole type crystallizer copper tube 4 according to different water-cooling structure types.

[0045] Furthermore, for crystallizer copper tubes with different water-cooling structures, the final design taper is the hot taper of the crystallizer copper tube for each water-cooling structure.

[0046] Figure 5 The paper presents the cold taper curves of copper tubes with a cross-section of 160mm × 160mm, HRB400 steel, and a casting speed of 5.0m / min, calculated using the layer-by-layer method model, as well as the actual design taper curves of copper tubes in various water-cooled crystallizer structures. Because the three-dimensional thermal deformation of copper tubes in different water-cooled crystallizer structures varies during casting, the hot taper curves better reflect the actual situation.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for determining the hot taper of a crystallizer copper tube, characterized in that, Includes the following steps: S1. Establish a cold taper layer model for the copper tube of the crystallizer and calculate the cold taper of the copper tube of the crystallizer based on the steel composition, billet cross-sectional dimensions and casting speed. S2 Establish a thermo-mechanical coupling mathematical model of copper tubes in crystallizers with different water-cooled structures. Use the cold taper obtained in step S1 as the input condition, and obtain the heat flux density distribution law of copper tubes in crystallizers with different water-cooled structures in the height direction and circumferential direction through simulation calculation. S3 Establish three-dimensional thermal deformation models of copper tubes in crystallizers with different water-cooled structures. The heat flux density obtained in step S2 is used as the input condition for the copper tubes in crystallizers with different water-cooled structures. The three-dimensional thermal deformation of the copper tubes in crystallizers with different water-cooled structures is obtained through simulation calculation. S4. The cold taper obtained in step S1 and the three-dimensional thermal deformation of the copper tubes of different water-cooled crystallizers obtained in step S3 are superimposed to obtain the hot taper of the copper tubes of each water-cooled crystallizer. The basic idea of ​​the layer-by-layer method model in step S1 is to divide the cast billet in the crystallizer into several layers from the top to the bottom, with each layer having a thickness of [missing information]. h Then, based on the solidification shrinkage characteristics of the steel grade, a separate taper design is carried out for each layer; For element i, the basic equation can be established: In the formula, The width dimension of the upper layer of unit i. The narrow side dimension of unit i is the upper layer dimension. Let i be the width dimension of the lower layer. The dimension of the narrow side of unit i is in mm; h The height of cell i; The difference in volume between element i and element i-1, in mm. 3 ; The solidification shrinkage volume change rate of molten steel, % for - Fe volume fraction; The solid-state phase change shrinkage rate is %; The percentage is the rate of change of liquid volume during contraction.

2. The method for determining the hot taper of the crystallizer copper tube according to claim 1, characterized in that: The crystallizer copper tube (1) is divided into planar water-slot type crystallizer copper tube (2), water tank type crystallizer copper tube (3) and round hole type crystallizer copper tube (4) according to different water-cooling structure types.

3. The method for determining the hot taper of the crystallizer copper tube according to claim 1, characterized in that: For crystallizer copper tubes with different water-cooling structures, the final design taper is the hot taper of the crystallizer copper tube with its water-cooling structure.

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