Chamfered crystallizer narrow copper plate cooling water structure for high speed casting and its using method

Abstract

The application provides a chamfered crystallizer narrow copper plate cooling water structure for high-pulling-speed continuous casting and a use method thereof, and relates to the technical field of steel smelting, in particular to the chamfered crystallizer narrow copper plate cooling water structure for high-pulling-speed continuous casting, which specifically comprises the following parts: a middle part, a chamfered part, a circular cooling water pipeline, a cooling water inlet and a cooling water outlet; the middle part, the chamfered part, the circular cooling water pipeline, the cooling water inlet and the cooling water outlet are integrally formed; the chamfered part is located on both sides of the middle part, and the middle part and the chamfered part are both internally provided with the circular cooling water pipeline; the cooling water inlet is arranged at one end of the back middle part and one end of the back chamfered part, and the cooling water outlet is arranged at the other end of the back middle part and the other end of the back chamfered part; the cooling water inlet is connected with one end of the circular cooling water pipeline, and the cooling water outlet is connected with the other end of the circular cooling water pipeline; the axis of the circular cooling water pipeline in the chamfered part is at an angle of 5°-15° with the normal line of the chamfered surface. The application prevents the generation of cracks in the chamfered part during high-pulling-speed continuous casting through structure optimization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel smelting, in particular to a chamfered mold narrow face copper plate cooling water structure for high-speed continuous casting and a using method thereof. BACKGROUND

[0002] The chamfered mold is an important technology to solve the slab corner transverse crack and the plate and strip edge straight crack defects, and has been industrialized applied on the slab continuous casting machine of many domestic steel plants. However, it is found in production practice that when the chamfered mold is used for high-speed continuous casting of micro-alloy steel, peritectic steel and hypoperitectic steel, the corner longitudinal crack of the continuous casting slab is prone to occur, and even the leakage accident occurs.

[0003] The invention patent with the publication number CN119387528A discloses a low-carbon high-sulfur steel chamfered mold high-speed continuous casting casting method, which mainly solves the problem of serious casting slab narrow face depression and easy crack defects by adjusting the taper and water quantity of the narrow face copper plate and the overheating degree of the molten steel.

[0004] The invention patent with the publication number CN118060504A discloses a method for improving the corner longitudinal crack of the chamfered mold carbon steel casting slab, and the feature is that the working surface structure of the narrow face copper plate is designed as a double taper structure, the taper of the copper plate in the range of 660-680mm from the lower opening is 1.0-1.4% / m, and the taper of the upper region of the copper plate is 2.4% / m.

[0005] The invention patent with the publication number CN116751922A discloses a method for reducing the corner longitudinal crack of the chamfered mold high-carbon steel casting slab, and the feature is that the additional taper of the chamfered mold narrow face is increased by 0.5-2mm based on the original taper.

[0006] The invention patent with the publication number CN116550946A discloses a chamfered mold casting slab corner longitudinal crack suppression method, and the feature is that the risk area of the corner longitudinal crack defect is determined by obtaining the shell thickness distribution information and the shell thickness uniformity in the chamfered mold, and then the taper of the mold is determined.

[0007] In summary, in view of the corner longitudinal crack of the chamfered slab and the high-speed continuous casting technical problem, metallurgical scholars have carried out a lot of research work in recent years, most of which are around the design of the mold taper to control the corner longitudinal crack, and there are few reports on the analysis and research from the perspective of the optimization of the chamfered mold copper plate cooling structure. SUMMARY

[0008] The purpose of the present application is to overcome the defects of the prior art, and provide a chamfered mold narrow face copper plate cooling water structure for high-speed continuous casting, which comprises:

[0009] Middle section, chamfered section, circular cooling water pipe, cooling water inlet and cooling water outlet;

[0010] The central section, chamfered section, circular cooling water pipe, cooling water inlet, and cooling water outlet are integrally formed; the chamfered section is located on both sides of the central section, and circular cooling water pipes are provided inside both the central section and the chamfered section; the cooling water inlet is located at one end of the central section of the back and one end of the chamfered section of the back, and the cooling water outlet is located at the other end of the central section of the back and the other end of the chamfered section of the back; the cooling water inlet is connected to one end of the circular cooling water pipe, and the cooling water outlet is connected to the other end of the circular cooling water pipe;

[0011] The inner diameter of the circular cooling water pipe inside the chamfered portion is set to 85% to 95% of the inner diameter of the circular cooling water pipe inside the middle portion.

[0012] The angle between the internal cooling water inlet of the chamfered part and the normal of the chamfered surface is 5°~15°.

[0013] Furthermore, the axial spacing d1 of adjacent circular cooling water pipes in the middle section is equal and ≥18mm in the width w direction of the narrow copper plate, and the axial spacing d2 of adjacent circular cooling water pipes in the chamfered section is equal in the width w direction of the narrow copper plate. The axial spacing d2 of adjacent circular cooling water pipes in the chamfered section is 85%~100% of the axial spacing d1 of adjacent circular cooling water pipes in the middle section.

[0014] Furthermore, the calculation method for the inner diameter of the central inner circular cooling water pipe is as follows:

[0015] Where D is the inner diameter of the central inner circular cooling water pipe.

[0016] Furthermore, each circular cooling water pipe is individually connected to a cooling water inlet and a cooling water outlet, and the cross-sectional area of ​​the circular cooling water pipe is greater than or equal to the cross-sectional area of ​​the cooling water inlet and the cross-sectional area of ​​the circular cooling water pipe is greater than or equal to the cross-sectional area of ​​the cooling water outlet.

[0017] Furthermore, the distance from the central internal circular cooling water pipe to the working surface of the narrow copper plate is ≥18mm, the distance from the central internal circular cooling water pipe to the back of the narrow copper plate is ≥16mm, and the distance from the chamfered internal circular cooling water pipe to the working surface of the narrow copper plate is 85%~100% of the distance from the central internal circular cooling water pipe to the working surface of the narrow copper plate.

[0018] Furthermore, the inner wall of the circular cooling water pipe is provided with a spiral guide groove.

[0019] Further, the distance from the circular cooling water pipe to the narrow surface copper plate working surface gradually increases from the cooling water outlet to the cooling water inlet in the direction of the blank drawing.

[0020] A method for using the chamfer crystallizer narrow surface copper plate cooling water structure for high-pulling-speed continuous casting, comprising:

[0021] Adjusting the flow rate of each circular cooling water pipe to make the temperature fluctuation of the narrow surface copper plate working surface be ≤15℃;

[0022] According to the thermal shrinkage coefficient of the steel grade, the water inflow of each cooling water inlet is adjusted in real time.

[0023] Further, the specific method for adjusting the water inflow of each cooling water inlet according to the thermal shrinkage coefficient of the steel grade is:

[0024] For peritectic steel, the water inflow of the cooling water inlet located at the chamfer part is increased by 10%~20% compared with the middle part;

[0025] For high-carbon steel, the water inflow of the cooling water inlet located at the middle part is increased by 5%~15% compared with the chamfer part.

[0026] Further, the specific method for adjusting the flow rate of each circular cooling water pipe to make the temperature fluctuation of the narrow surface copper plate working surface be ≤15℃ is:

[0027] Through independent flow adjusting valves, each circular cooling water pipe is controlled in real time, and the flow rate difference of each circular cooling water pipe in the middle part and the flow rate difference of each circular cooling water pipe in the chamfer part are all ≤0.8m / s.

[0028] The beneficial effects of the present application are:

[0029] 1. The integrally formed circular cooling pipe design of the present application has small flow resistance, avoids turbulent flow and dead zones, compared with the traditional water jacket type or water tank type cooling structure. The present application innovatively proposes transverse partition control of the middle part and the chamfer part, realizes quantifiable and predictable design of cooling uniformity through accurate flow rate difference control (≤1.0m / s) and pipe parameter calculation formula. For the problem of longitudinal corner cracks under high pulling speed (≥1.45m / min) conditions, the present application effectively deals with the severe flow and heat transfer fluctuations in the crystallizer through high flow rate cooling (≥12m / s), which solves the technical problem of insufficient corner cooling of the existing chamfer crystallizer under high pulling speed conditions. The implementation effect of the production line shows that for corner crack sensitive steel grades, under high pulling speed conditions (≥1.45m / min), after using the crystallizer narrow surface copper plate of the present embodiment, compared with the traditional crystallizer, the occurrence rate of the corner crack of the cast blank is reduced from 87.8% to 12.3%.

[0030] 2. By optimizing the cooling structure, the water velocity difference of each circular cooling water pipe inside the narrow copper plate is reduced, which helps to improve the uniformity of transverse heat transfer. Stable control of the water velocity of the circular cooling water pipe strengthens the cooling of the narrow face and corner of the casting blank, which effectively promotes the uniform growth of the narrow face and corner shell of the casting blank, prevents the occurrence of longitudinal cracks in the corner of the casting blank, and fundamentally reduces the risk of longitudinal crack in the corner of sensitive steel such as micro-alloyed steel and peritectic steel under high-speed continuous casting conditions, while avoiding the accident of breakout caused by uneven cooling.

[0031] 3. The number of pipes is determined by quantitative calculation of the width and axial spacing, the size of the pipe is determined by the correlation formula of flow rate, flow velocity and pipe diameter, and the flow rate of each cooling pipe can be independently regulated by independent water supply design. This fine design makes the cooling structure flexible to adapt to different sizes and process requirements of the crystallizer, improving the universality and scalability of the method.

[0032] 4. By setting the inner diameter of the chamfer cooling pipe to 85%-95% of the middle part and the axial spacing to 85%-100%, and limiting the absolute difference while maintaining the proportion of the distance between the cooling pipe and the working surface, the cooling intensity of the chamfer area and the middle area is balanced. This design not only avoids the corner transverse cracks caused by overcooling of the chamfer, but also prevents longitudinal cracks caused by insufficient cooling.

[0033] 5. According to the real-time temperature data of the crystallizer thermocouple, the water inflow is dynamically adjusted, so that the temperature fluctuation of the working surface a1 of the narrow copper plate is ≤15℃. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The back surface a2 structure diagram of the cooling water structure of the chamfer crystallizer narrow copper plate for high-speed continuous casting.

[0035] Figure 2 The side view of the cooling water structure of the chamfer crystallizer narrow copper plate for high-speed continuous casting. Figure 1 The cross section A1 diagram of the cooling water inlet.

[0036] Figure 3 The cross section A2 diagram of the area except the cooling water inlet and outlet of the cooling water structure. Figure 1 The cross section A2 diagram of the area except the cooling water inlet and outlet of the cooling water structure.

[0037] Figure 4 Another back surface a2 structure diagram of the cooling water structure of the chamfer crystallizer narrow copper plate for high-speed continuous casting.

[0038] Figure 5 The side view of the cooling water structure of the chamfer crystallizer narrow copper plate for high-speed continuous casting. Figure 1

[0039] Figure 6 The structure diagram of the circular cooling water pipe.

[0040] ​Figure 7 This is a schematic diagram of the inner diameter of a circular cooling water pipe.

[0041] Figure reference numerals: 1-Center; 2-Chamfered section; 3-Circular cooling water pipe; 31-Spiral guide groove; 4-Cooling water inlet; 5-Cooling water outlet; d1-Axial distance between adjacent circular cooling water pipes inside the center; d2-Axial distance between adjacent circular cooling water pipes inside the chamfered section; d3-Pitch of the spiral guide groove; d4-Depth of the spiral guide groove; a1-Working surface; a2-Back side; a3-Meniscus area; w-Width of the narrow copper plate; w1-Width of the center; w2-Width of the chamfered section; L1-Tangent of the chamfered surface; L2-Normal of the chamfered surface; θ-Angle between the normal of the chamfered surface and the cooling water inlet. Detailed Implementation

[0042] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0043] like Figure 1 As shown, in the crystallizer used in continuous casting, after the narrow-faced copper plate is assembled with the water tank, the cooling water is injected into the back side a2 of the copper plate through a square window. The cooling water from the square window is injected into the corresponding circular cooling water pipes 3 through each cooling water inlet 4, and then flows into the interior of the copper plate. The cooling water then flows out through each cooling water outlet 5 and re-enters the water tank, thus achieving circulating cooling. The shapes of the cooling water inlets 4 and cooling water outlets 5 can also be... Figure 4 The circle shown.

[0044] Example 1

[0045] A cooling water structure for a narrow-faced copper plate in a chamfered crystallizer for high-speed continuous casting includes a central section 1, a chamfered section 2, a circular cooling water pipe 3, a cooling water inlet 4, and a cooling water outlet 5. The central section 1, chamfered section 2, circular cooling water pipe 3, cooling water inlet 4, and cooling water outlet 5 are integrally formed. The chamfered section 2 is located on both sides of the central section 1. Circular cooling water pipes 3 are provided inside both the central section 1 and the chamfered section 2. The cooling water inlet 4 is located at one end of the central section 1 and one end of the chamfered section 2 on the back side a2. The cooling water outlet 5 is located at the other end of the central section 1 and the other end of the chamfered section 2 on the back side a2. The cooling water inlet 4 is connected to one end of the circular cooling water pipe 3, and the cooling water outlet 5 is connected to the other end of the circular cooling water pipe 3.

[0046] To more clearly illustrate the cooling water structure described in this invention, Figure 1 The narrow copper plate shown has the following specific structure.

[0047] As a preferred embodiment, the number of circular cooling water pipes 3 is determined according to the width w1 of the middle part 1, the width w2 of the chamfered part 2 and the axial spacing of adjacent circular cooling water pipes 3. The width w1 of the middle part 1 is divided by the axial spacing d1 of adjacent circular cooling water pipes 3 in the middle part 1, and the result is rounded down to obtain the maximum number of circular cooling water pipes 3 in the middle part 1. The width w2 of the chamfered part 2 is divided by the axial spacing d2 of adjacent circular cooling water pipes 3 in the chamfered part 2, and the result is rounded down to obtain the maximum number of circular cooling water pipes 3 in the chamfered part 2. As shown in FIGS. 1, 2 and 3, the axial spacing d1 of adjacent circular cooling water pipes 3 in the middle part 1 is equal and ≥18mm, and the axial spacing d2 of adjacent circular cooling water pipes 3 in the chamfered part 2 is equal. The axial spacing d2 of adjacent circular cooling water pipes 3 in the chamfered part 2 is 85%~100% of the axial spacing d1 of adjacent circular cooling water pipes 3 in the middle part 1. The width w1 of the middle part 1 and the width w2 of the chamfered part 2 are measured to be 156mm and 41mm respectively. It can be known that the number of circular cooling water pipes 3 in the middle part 1 should be less than 156÷18≈8.6, and the number of circular cooling water pipes 3 in the chamfered part 2 should be less than 41÷(18×0.85)≈2.7. In this embodiment, 7 circular cooling water pipes 3 are designed in the middle part 1, and 2 circular cooling water pipes 3 are designed in the chamfered part 2, and a total of 11 circular cooling water pipes 3 are designed. Figure 2 and Figure 3 As shown in FIGS. 1, 2 and 3, the axial spacing d1 of adjacent circular cooling water pipes 3 in the middle part 1 is equal and ≥18mm, and the axial spacing d2 of adjacent circular cooling water pipes 3 in the chamfered part 2 is equal. The axial spacing d2 of adjacent circular cooling water pipes 3 in the chamfered part 2 is 85%~100% of the axial spacing d1 of adjacent circular cooling water pipes 3 in the middle part 1. The width w1 of the middle part 1 and the width w2 of the chamfered part 2 are measured to be 156mm and 41mm respectively. It can be known that the number of circular cooling water pipes 3 in the middle part 1 should be less than 156÷18≈8.6, and the number of circular cooling water pipes 3 in the chamfered part 2 should be less than 41÷(18×0.85)≈2.7. In this embodiment, 7 circular cooling water pipes 3 are designed in the middle part 1, and 2 circular cooling water pipes 3 are designed in the chamfered part 2, and a total of 11 circular cooling water pipes 3 are designed.

[0048] The axial spacing d1 of adjacent circular cooling water pipes 3 in the middle part 1 must be ≥18mm, and the axial spacing d2 of adjacent circular cooling water pipes 3 in the chamfered part 2 is 85%~100% of the axial spacing d1 of adjacent circular cooling water pipes 3 in the middle part 1. In essence, it is to ensure that there is enough minimum wall thickness of copper plate material between the circular cooling water pipes 3, which effectively prevents the risks of local stress concentration, thermal fatigue cracking or high-pressure cooling water breakthrough caused by too thin wall thickness, and fundamentally guarantees the operation reliability and service life of the crystallizer under high temperature, high pressure and high load working conditions. The axial spacing d2 of adjacent circular cooling water pipes 3 in the chamfered part 2 is 85%~100% of the axial spacing d1 of adjacent circular cooling water pipes 3 in the middle part 1, which is to enhance the cooling capacity of the chamfered part 2 to the cast slab. The number of circular cooling water pipes 3 is determined by dividing the width of the region by the fixed spacing, so that the circular cooling water pipes 3 are evenly distributed in the width w direction of the narrow copper plate. This uniform layout is the physical basis for realizing the uniformity of the transverse cooling of the cast slab. It can promote the uniform growth of the narrow slab shell and avoid thermal stress cracks caused by uneven cooling, which is crucial for high-speed continuous casting to produce high-quality cast slabs. In addition, the middle part 1 and the chamfered part 2 are designed differently, and the number of circular cooling water pipes 3 in the two regions is calculated respectively, which provides a physical basis for independent control of the two regions.

[0049] In a preferred embodiment, the distance from the internal circular cooling water pipe 3 of the middle section 1 to the working surface a1 of the narrow copper plate is ≥18mm, the distance from the internal circular cooling water pipe 3 of the middle section 1 to the back surface a2 of the narrow copper plate is ≥16mm, the distance from the internal circular cooling water pipe 3 of the chamfered section 2 to the working surface a1 of the narrow copper plate is 85%~100% of the distance from the internal circular cooling water pipe 3 of the middle section 1 to the working surface a1 of the narrow copper plate, the difference between the distances of each internal circular cooling water pipe 3 of the middle section 1 to the working surface a1 of the narrow copper plate is ≤3mm, and the difference between the distances of each internal circular cooling water pipe 3 of the chamfered section 2 to the working surface a1 of the narrow copper plate is ≤3mm, to ensure the uniformity of cooling intensity. In this embodiment, the distance between each circular cooling water pipe 3 in the middle section 1 and the working surface a1 of the copper plate remains the same. The distance between the circular cooling water pipe 3 inside the chamfered section 2 and the working surface a1 of the copper plate is 85%~100% of the distance between the circular cooling water pipe 3 inside the middle section 1 and the working surface a1 of the copper plate. In this embodiment, the distance between each circular cooling water pipe 3 in the middle section 1 and the working surface a1 of the copper plate is designed to be 18mm. The working surface a1 of the narrow copper plate is... Figure 1 The opposite side of the back a2 in the middle. By setting the distance from the internal circular cooling water pipe 3 of the chamfered part 2 to the working surface a1 to 85%~100% of the distance from the internal circular cooling water pipe 3 of the middle part 1, the cooling capacity of the chamfered part 2 for the billet is enhanced, which is the key to solving the longitudinal cracks at the corner of the billet and ensuring the uniform growth of the billet shell.

[0050] In a preferred embodiment, the distance from the circular cooling water pipe 3 to the working surface a1 of the narrow copper plate gradually increases in the drawing direction from the cooling water outlet 5 to the cooling water inlet 4. For example... Figure 5 The distance from the circular cooling water pipe 3 located in the upper meniscus region a3 of the middle section 1 to the working surface a1 of the narrow copper plate is set to 18-20 mm, and the distance from the meniscus region a3 to the cooling water outlet 5 is 0-200 mm. The distance from the circular cooling water pipe 3 located in the lower part of the middle section 1, 400-800 mm from the cooling water outlet 5, to the working surface a1 of the narrow copper plate is set to 22-25 mm. This ensures that the cooling intensity dynamically changes as the billet descends and the shell thickens, achieving differentiated cooling with stronger cooling at the top and weaker cooling at the bottom. The upper part (meniscus region a3) requires strong cooling to quickly form the shell; therefore, the circular cooling water pipe 3 here is close to the working surface a1 (18-20 mm). The lower part of the shell has already formed and begins to shrink, requiring gentle cooling to reduce thermal stress and prevent cracking; therefore, the circular cooling water pipe 3 here is farther from the working surface a1 (22-25 mm). This is an optimization to solve the problem of thermal stress cracking in the shell and to adapt to the solidification process.

[0051] The combination of the layout design of the circular cooling water pipe 3 in the two dimensions of the transverse and longitudinal directions forms a very delicate three-dimensional cooling scheme. At the top of the narrow copper plate (for example, 100 mm away from the cooling water outlet 5), the longitudinal gradient requires that the distance between the circular cooling water pipe 3 and the working surface a1 is 19 mm (in line with the range of 18-20 mm); the transverse uniformity requires that at this longitudinal height (100 mm away from the cooling water outlet 5), the distance between the circular cooling water pipe 3 in the middle part 1 and the working surface a1 is set as the reference (for example, 19 mm), and the distance between the circular cooling water pipe 3 in the chamfered part 2 and the working surface a1 must be controlled between about 16 mm and 19 mm (85%-100% of the reference). At the bottom of the narrow copper plate (for example, 600 mm away from the cooling water outlet 5), the longitudinal gradient requires that the distance between the circular cooling water pipe 3 and the working surface a1 is 23.5 mm (in line with the range of 22-25 mm); the transverse uniformity requires that at this longitudinal height (600 mm away from the cooling water outlet 5), the distance between the circular cooling water pipe 3 in the middle part 1 and the working surface a1 is set as the new reference (for example, 23.5 mm), and the distance between the circular cooling water pipe 3 in the chamfered part 2 and the working surface a1 must be controlled between about 20 mm and 23.5 mm (85%-100% of the new reference).

[0052] As a preferred embodiment, the chamfered surface tangent L1 and the chamfered surface normal L2 are made on the surface of the chamfered part 2, and the included angle θ between the cooling water inlet 4 inside the chamfered part 2 and the chamfered surface normal L2 is 5°-15°. This included angle design makes the injection direction of the cooling water more directly aligned with the corner area of the casting blank where the heat load is most concentrated and cracks are most likely to occur. This ensures that the cooling efficiency can be maximally transmitted to the corner blank shell that most needs to be strengthened, avoiding the loss or deviation of cooling energy, thereby efficiently promoting the rapid and uniform growth of the corner blank shell.

[0053] As a preferred embodiment, the inner diameter of each circular cooling water pipe 3 in the middle part 1 is kept equal, and the inner diameter of each circular cooling water pipe 3 in the chamfered part 2 is equal and 85% to 95% of the inner diameter of each circular cooling water pipe 3 in the middle part 1. According to the principle of fluid mechanics, under the condition of constant total cooling water flow, reducing the inner diameter of the pipe can significantly increase the flow rate of the cooling water. The flow rate is a key factor affecting the heat exchange efficiency. The higher the flow rate, the greater the heat exchange coefficient, and the stronger the cooling capacity, so as to implement directional strengthening cooling on the corner part of the casting blank where the heat load is concentrated. In high-speed continuous casting, the corner part of the casting blank is the area where stress is concentrated and longitudinal cracks are most likely to occur. By strengthening the cooling here, the corner shell can be promoted to grow quickly and uniformly, so as to have sufficient thickness and strength to resist the generation of cracks, and fundamentally solve the process problem. If the cooling of the chamfered part 2 is too severe, although the longitudinal cracks are inhibited, another defect, corner transverse cracks, may be caused. Controlling the inner diameter of each circular cooling water pipe 3 in the chamfered part 2 to be 85% to 95% of the inner diameter of each circular cooling water pipe 3 in the middle part 1 can provide necessary strengthening cooling and avoid overcooling, and achieve the best balance between inhibiting longitudinal cracks and transverse cracks.

[0054] To ensure that the middle part 1 reaches the maximum cooling water flow, the preset flow rate of the circular cooling water pipe 3 in the middle part 1 is higher than 12 m / s. In this embodiment, the maximum cooling water flow of the middle part 1 is 0.55 m 3 / min, and the number of circular cooling water pipes 3 in the middle part 1 is 7. The calculation method of the inner diameter D of the circular cooling water pipe in the middle part 1 is as follows:

[0055] In order to make the preset flow rate of the circular cooling water pipe 3 in the middle part 1 greater than 12 m / s, according to the above formula, the inner diameter D of the circular cooling water pipe 3 in the middle part 1 should be less than 11.78 mm. In this embodiment, the inner diameter D of the circular cooling water pipe 3 in the middle part 1 is designed to be 8 mm. The traditional design may rely on experience or trial and error to determine the pipe size, while this formula takes the flow rate, the core performance parameter of the cooling system, as the starting point and quantifiable target of the design. Through the known maximum cooling water flow of the middle part 1 and the number of circular cooling water pipes 3 in the middle part 1, the inner diameter D of the circular cooling water pipe 3 in the middle part 1 required to achieve the preset flow rate of the circular cooling water pipe 3 in the middle part 1 can be accurately calculated. This makes the design process from vague to accurate, and the cooling effect becomes a predictable and calculable index at the drawing stage.

[0056] As a preferred embodiment, as Figure 6 and Figure 7As shown, the inner wall of the circular cooling water pipe 3 is also provided with a spiral flow guide groove 31, the groove depth d4 is 0.5-1.0 mm, the pitch d3 of the circular cooling water pipe 3 in the middle part 1 is 1.5-2.0 times of the inner diameter D, and the groove depth d4 and the pitch d3 of the spiral flow guide groove 31 in the chamfered part 2 are 85%-95% of the groove depth d4 and the pitch d3 of the spiral flow guide groove 31 in the circular cooling water pipe 3 in the middle part 1. In the ordinary smooth pipe without the flow guide groove, the cooling water basically flows in a straight line (advection), and the water flow near the pipe wall is slow, which forms a relatively static boundary layer. This boundary layer hinders the efficient transfer of heat from the high-temperature copper plate wall to the low-temperature water flow in the center of the pipe. The groove forces the water flow to rotate along a spiral path while moving forward. This rotating motion generates strong centrifugal force and shear effect, which can effectively break the stagnant thermal boundary layer near the pipe wall and continuously and violently mix the high-temperature water with the low-temperature water in the center. The spiral path is longer than the straight path, which increases the effective heat exchange distance and time of the cooling water in the pipe. This can increase the heat exchange coefficient by 15%-25%, and under the same water flow rate and temperature, the cooling effect of the narrow copper plate is stronger, and it can better cope with the extreme heat load brought by high drawing speed.

[0057] As a preferred embodiment, the cross-sectional area of all circular cooling water pipes 3 is greater than or equal to the cross-sectional area of the cooling water inlet 4 and the cross-sectional area of the circular cooling water pipe 3 is greater than or equal to the cross-sectional area of the cooling water outlet 5. This design can avoid flow bottlenecks and ensure the design flow rate. In the cooling system, cooling water flows from the water inlet main pipe into the circular cooling water pipe 3 through the cooling water inlet 4. If the cross-sectional area of the cooling water inlet 4 is smaller than the circular cooling water pipe 3 itself, it will become a throttle or bottleneck, and the same applies to the cooling water outlet 5.

[0058] As a preferred embodiment, during the pouring process, the intelligent pouring control system monitors the thermocouple data embedded in the middle part 1 and the chamfered part 2 in real time, dynamically adjusts the water flow rate according to the pouring speed, steel grade composition, temperature and other process parameters, and ensures that the temperature fluctuation of the copper plate working surface a1 is ≤15℃.

[0059] According to the cooling structure of the copper plate described above, a cooling water flow physical model with the same actual shape is established, and flow simulation software is used to calculate the water flow rate and its distribution characteristics in each water joint. The cooling water inlet 4, the cooling water outlet 5 and the circular cooling water pipe 3 are mainly optimized and adjusted. The method and goal is to obtain a relatively optimal cooling structure through several flow simulation calculations, so that the maximum difference of the flow rate of each circular cooling water pipe 3 is less than 1.0 m / s. In this embodiment, numerical simulation calculation shows that the maximum difference of the flow rate of each circular cooling water pipe 3 is 0.8 m / s.

[0060] The production line implementation effect shows that for the angle crack sensitive steel grade (such as high carbon steel), under the high speed operation (≥1.45m / min), compared with the traditional crystallizer, the occurrence rate of the casting slab angle crack is reduced from 87.8% to 12.3% after the crystallizer narrow face copper plate of the embodiment is used.

[0061] Embodiment 2

[0062] In order to further illustrate the scheme of the application, another specific structure is provided. Thus, embodiment 1 is different in that the cooling water inlet 4 and the cooling water outlet 5 are designed in a circular structure. Through numerical simulation calculation, it is found that the maximum difference of the flow rate of each circular cooling water pipe 3 is 0.7m / s.

[0063] Embodiment 3

[0064] A method for using the chamfered crystallizer narrow face copper plate cooling water structure for high speed continuous casting, comprising:

[0065] The flow rate of each circular cooling water pipe 3 is adjusted so that the temperature fluctuation of the narrow face copper plate working surface a1 is ≤15℃, directly solving the most difficult problem of the angle longitudinal crack of the high speed continuous casting. The stable temperature field ensures the uniformity of the shell growth, eliminates the conditions for the crack caused by the uneven thermal stress from the root, and significantly reduces the risk of the leakage accident. The severe temperature fluctuation is the main reason for the thermal crack and thermal deformation of the copper plate. By suppressing the temperature fluctuation within 15℃, the thermal fatigue effect of the copper plate is greatly reduced, the service life of the narrow face copper plate is significantly prolonged, and the production maintenance cost and downtime are reduced.

[0066] According to the thermal shrinkage coefficient of the steel grade, the water inflow of each cooling water inlet 4 is adjusted in real time, which is a precise protection for the disease, and significantly improves the qualified rate of the casting slab quality of different steel grades.

[0067] As a preferred embodiment, the specific method for adjusting the water inflow of each cooling water inlet 4 according to the thermal shrinkage coefficient of the steel grade is:

[0068] For peritectic steel, the water inflow of the cooling water inlet 4 located at the chamfered portion 2 is increased by 10%~20% compared with the middle portion 1. The peritectic reaction occurs during the solidification process of the peritectic steel, accompanied by significant volume shrinkage, resulting in a very fragile primary shell and poor contact with the copper plate (forming an air gap), which reduces the heat flux density. At this time, as the weak area of two-dimensional heat transfer, the angle portion grows the slowest and is most prone to longitudinal cracks. By actively increasing the cooling water amount of the chamfered portion, the heat exchange of the region can be forcibly enhanced, making up for the insufficient cooling caused by the air gap, providing additional support for the fragile angle portion shell, and significantly promoting the uniform and rapid growth of the shell, thereby effectively inhibiting the typical angle longitudinal crack of the peritectic steel.

[0069] For high carbon steel (mass percentage of carbon is greater than 0.60%), the water flow of the water inlet 4 of the middle part 1 is increased by 5% to 15% compared with the chamfered part 2. The solidification range of high carbon steel is wide, and the high-temperature strength of the shell is low, so coarse columnar crystals are easily formed at the solidification front. During the process of drawing the shell, the middle part region is separated from the copper plate to form an air gap due to shrinkage, which becomes a weak cooling point and easily leads to uneven shell thickness or even drawing leakage. By appropriately strengthening the middle cooling, the shell in the middle part region can have sufficient growth rate and thickness, balance the solidification profile of the whole narrow surface, reduce the risk of being torn due to the insufficient thickness and strength of the middle shell, and thus improve the stability of high carbon steel continuous casting and the quality of the cast slab.

[0070] As a preferred embodiment, the flow rate of each circular cooling water pipe 3 is adjusted to make the temperature fluctuation of the working surface a1 of the narrow surface copper plate ≤15℃, and the specific method is as follows:

[0071] Each circular cooling water pipe is controlled in real time by an independent flow regulating valve, so that the flow rate difference of each circular cooling water pipe in the middle part and the flow rate difference of each circular cooling water pipe in the chamfered part are both ≤0.8m / s. This can be realized by connecting the intelligent control system to the cooling water inlet 4. This means that the heat absorbed by the narrow surface copper plate in the width w direction can be almost evenly taken away, creating a highly uniform transverse temperature field, which provides ideal conditions for the uniform growth of the shell of the cast slab. The thickness difference of the shell caused by uneven cooling and the internal thermal stress caused thereby are completely eliminated, which directly prevents the surface longitudinal cracks and depressions of the cast slab, and significantly improves the surface quality of the product.

[0072] In the present application, if there are terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicating the orientation or positional relationship, the orientation or positional relationship shown in the drawings is based on, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the orientation or positional relationship in the present application are only used for exemplary description, and cannot be understood as a limitation on the present application. For those skilled in the art, the specific meaning of the above terms can be understood in combination with the drawings and according to the specific circumstances.

[0073] Unless otherwise defined, all terms used in disclosing aspects of the application, such as "a" or "an", are to be construed to be inclusive of both singular and plural, unless otherwise indicated by context. All publications, patent applications, patents, and other references mentioned in this specification are herein incorporated by reference in their entirety for the purpose of over-coming any non-enablement inhering in this disclosure.

[0074] The above description is only the preferred embodiment of the present application, not any form of limitation to the present application, any simple modification or equivalent change to the above embodiment according to the technical essence of the present application, falls within the protection scope of the present application.

Claims

1. A cooling water structure for a narrow-faced copper plate in a chamfered crystallizer used in high-speed continuous casting, characterized in that, include: The middle section (1), the chamfered section (2), the circular cooling water pipe (3), the cooling water inlet (4), and the cooling water outlet (5); The middle part (1), the chamfered part (2), the circular cooling water pipe (3), the cooling water inlet (4) and the cooling water outlet (5) are integrally formed; The chamfered portion (2) is located on both sides of the middle portion (1), and both the middle portion (1) and the chamfered portion (2) are provided with circular cooling water pipes (3). The cooling water inlet (4) is located at one end of the middle part (1) of the back (a2) and one end of the chamfered part (2) of the back (a2), and the cooling water outlet (5) is located at the other end of the middle part (1) of the back (a2) and the other end of the chamfered part (2) of the back (a2); The cooling water inlet (4) is connected to one end of the circular cooling water pipe (3), and the cooling water outlet (5) is connected to the other end of the circular cooling water pipe (3); Wherein, the inner diameter of the circular cooling water pipe (3) inside the chamfered part (2) is set to 85%~95% of the inner diameter of the circular cooling water pipe inside the middle part (1); The angle (θ) between the internal cooling water inlet (4) of the chamfered part (2) and the normal (L2) of the chamfered surface is 5°~15°; The axial spacing d1 of adjacent circular cooling water pipes (3) in the middle part (1) is equal and ≥18mm in the direction of the width w of the narrow copper plate. The axial spacing d2 of adjacent circular cooling water pipes (3) in the chamfered part (2) is equal in the direction of the width w of the narrow copper plate. The axial spacing d2 of adjacent circular cooling water pipes (3) in the chamfered part (2) is 85%~100% of the axial spacing d1 of adjacent circular cooling water pipes (3) in the middle part (1). The calculation method for the inner diameter of the inner circular cooling water pipe (3) in the middle section (1) is as follows: Where D is the inner diameter of the inner circular cooling water pipe (3) in the middle (1).

2. The cooling water structure for the narrow-faced copper plate of the chamfered crystallizer for high-speed continuous casting according to claim 1, characterized in that: Each circular cooling water pipe (3) is individually connected to a cooling water inlet (4) and a cooling water outlet (5). The cross-sectional area of ​​the circular cooling water pipe (3) is greater than or equal to the cross-sectional area of ​​the cooling water inlet (4) and the cross-sectional area of ​​the circular cooling water pipe (3) is greater than or equal to the cross-sectional area of ​​the cooling water outlet (5).

3. The cooling water structure for the narrow-faced copper plate of the chamfered crystallizer for high-speed continuous casting according to claim 1, characterized in that: The distance from the inner circular cooling water pipe (3) of the middle part (1) to the working surface (a1) of the narrow copper plate is ≥18mm, the distance from the inner circular cooling water pipe (3) of the middle part (1) to the back surface (a2) of the narrow copper plate is ≥16mm, and the distance from the inner circular cooling water pipe (3) of the chamfered part (2) to the working surface (a1) of the narrow copper plate is 85%~100% of the distance from the inner circular cooling water pipe (3) of the middle part (1) to the working surface (a1) of the narrow copper plate.

4. The cooling water structure for the narrow-faced copper plate of the chamfered crystallizer for high-speed continuous casting according to claim 1, characterized in that: The inner wall of the circular cooling water pipe (3) is provided with a spiral guide groove (31).

5. The cooling water structure for the narrow-faced copper plate of the chamfered crystallizer for high-speed continuous casting according to claim 3, characterized in that: The distance from the circular cooling water pipe (3) to the working surface (a1) of the narrow copper plate gradually increases from the cooling water outlet (5) to the cooling water inlet (4) in the pulling direction.

6. A method of using the narrow-face copper plate cooling water structure for a chamfered crystallizer used in high-speed continuous casting as described in claim 1, characterized in that, include: Adjust the flow rate of each circular cooling water pipe (3) so that the temperature fluctuation of the working surface (a1) of the narrow copper plate is ≤15℃; The flow rate of each cooling water inlet (4) is adjusted in real time according to the thermal shrinkage coefficient of the steel.

7. The method of using the narrow-face copper plate cooling water structure for a chamfered crystallizer used in high-speed continuous casting according to claim 6, characterized in that, The specific method for adjusting the inlet flow rate of each cooling water inlet (4) in real time according to the thermal shrinkage coefficient of the steel is as follows: For peritectic steel, the water flow rate of the cooling water inlet (4) located in the chamfered part (2) is increased by 10% to 20% compared with that in the middle part (1); For high carbon steel, the water flow rate of the cooling water inlet (4) located in the middle (1) is 5% to 15% higher than that of the chamfered part (2).

8. The method of using the narrow-face copper plate cooling water structure for a chamfered crystallizer used in high-speed continuous casting according to claim 6, characterized in that, The specific method for adjusting the flow rate of each circular cooling water pipe (3) to ensure that the temperature fluctuation of the working surface (a1) of the narrow copper plate is ≤15℃ is as follows: The flow rate difference between each circular cooling water pipe (3) in the middle section (1) and the flow rate difference between each circular cooling water pipe (3) in the chamfered section (2) are both ≤0.8m / s.

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