A method for stably controlling the thickness of continuous casting mold shell

Abstract

The present invention provides a method for stably controlling the shell thickness of a continuous casting crystallizer, controlling the water temperature of a cold water in the crystallizer to be below 40°C, controlling the water inlet pressure of a cold water in the crystallizer to be above 0.8MPa, controlling the fluctuation of the inverted taper of the copper tube of the crystallizer to be within 0.05% / m, and setting the water volume of the cold water in the crystallizer to increase with the increase of the casting speed and the temperature of the tundish. The invention establishes a special model for the primary cooling of the crystallizer by controlling the water inlet temperature, pressure and inverted taper of the copper tube of the crystallizer, thereby improving the uniformity of the primary cooling of the crystallizer, stabilizing the thickness of the crystallizer shell, and improving the quality of the casting. The method of the present invention has the following advantages: 1. It can effectively solve the problem of unstable shell thickness of the crystallizer shell out of the continuous casting machine, realize stable control of the shell thickness of the crystallizer shell out of the crystallizer, and improve the surface quality of the casting. 2. It is simple in design, easy to use, and highly operable.

Description

Technical Field

[0001] The invention belongs to the technical field of continuous casting in iron and steel metallurgy, and in particular relates to a method for stably controlling the thickness of a continuous casting crystallizer shell. Background Art

[0002] The crystallizer is the heart of the continuous casting machine and its most critical process equipment. Molten steel, after smelting and refining in the converter, is poured into the crystallizer via the ladle and tundish. The hot molten steel solidifies upon encountering the mold's copper tubes, forming a primary shell. This shell then continues to solidify and grow as it cools through the mold's cooling water.

[0003] Currently, the primary cooling water volume in the mold is generally controlled at a fixed rate. When the casting speed is low, the primary cooling water volume is high, resulting in excessive primary cooling intensity. This strong cooling of the primary mold shell can easily cause surface cracks. When the casting speed is high, the primary cooling water volume is low, resulting in a thin shell thickness, which can easily lead to quality defects such as bulging and squareness loss. Furthermore, due to fluctuations in the primary cooling water inlet temperature and pressure, the copper tube taper, the casting speed, and the tundish temperature, the solidification of the casting is uneven, and the thickness of the casting shell is unstable, which can easily lead to stress concentration and exacerbate the formation of surface cracks in the casting. Summary of the Invention

[0004] The object of the present invention is to provide a method for stably controlling the thickness of a continuous casting mold shell. The method of the present invention can achieve stable control of the thickness of the mold shell and improve the surface quality of the cast mold.

[0005] The present invention provides a method for stably controlling the shell thickness of a continuous casting crystallizer, which is characterized in that the water temperature of a cold water in the crystallizer is controlled to be below 40°C, the water inlet pressure of the cold water in the crystallizer is controlled to be above 0.8 MPa, the fluctuation of the inverted taper of the copper tube of the crystallizer is controlled to be within 0.05% / m, and the water volume of the cold water in the crystallizer is set to increase with the increase of the casting speed and the tundish temperature.

[0006] Preferably, the water temperature of the cold water in the crystallizer is controlled at 33-40°C, and the fluctuation of the inlet water temperature is controlled within 2°C.

[0007] Preferably, the temperature of the cold water in the crystallizer is controlled at 33-35°C in winter and 38-40°C in summer.

[0008] Preferably, the inlet pressure of the cold water in the crystallizer is controlled at 0.85-0.87 MPa.

[0009] Preferably, the fluctuation of the water inlet pressure of the cold water in the crystallizer is controlled within 0.02 MPa.

[0010] Preferably, the back taper of the copper tube of the crystallizer is controlled at 1.20-1.25% / m.

[0011] Preferably, the amount of cooling water in the crystallizer, the casting speed, and the tundish temperature satisfy the relationship shown in Formula I:

[0012] Q = a × V + b + c × (T-1520) Formula I;

[0013] In formula I, Q is the amount of water in the crystallizer cooling water, V is the casting speed, T is the tundish temperature, and a is (Q 最大 -B) / V 最大 , Q 最大 V is the maximum amount of cold water in the crystallizer, 最大 is the maximum billet drawing speed, b is the minimum amount of cooling water in the crystallizer, and c is between 5 and 10.

[0014] Preferably, the tundish temperature T is 1520-1560°C, and when the tundish temperature T is less than 1520°C, it is calculated as 1520°C; when the tundish temperature T is greater than 1560°C, it is calculated as 1560°C.

[0015] Preferably, the flow rate of the cold water in the crystallizer is not less than 8-10 m / s when the water volume of the cold water in the crystallizer is minimum, and the flow rate of the cold water in the crystallizer is not more than 12-14 m / s when the water volume of the cold water in the crystallizer is maximum.

[0016] Preferably, the shell is made of a steel containing one or more of niobium, vanadium, titanium and boron.

[0017] Preferably, the brand of the shell is Q355E, S355ML or C345.

[0018] The present invention provides a method for stably controlling the shell thickness of a continuous casting mold. The method involves controlling the temperature of the mold's cooling water below 40°C, the inlet pressure of the cooling water above 0.8 MPa, and the fluctuation of the mold's copper tube taper within 0.05% / m. The amount of cooling water in the mold is configured to increase with increasing casting speed and tundish temperature. By controlling the inlet temperature and pressure of the cooling water, as well as the inlet taper of the copper tube, the invention establishes a dedicated mold primary cooling model, thereby improving the uniformity of the mold primary cooling, stabilizing the mold shell thickness, and enhancing the quality of the cast mold.

[0019] The method of the present invention has the following advantages:

[0020] 1. It can effectively solve the problem of unstable shell thickness of the continuous casting machine, realize stable control of the shell thickness of the crystallizer, and improve the surface quality of the casting.

[0021] 2. Simple design, easy to use and highly operable. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0023] Figure 1 This is a picture of a casting blank prepared in Example 1 of the present invention;

[0024] Figure 2 This is a picture of another casting blank prepared in Example 1 of the present invention;

[0025] Figure 3 This is a picture of a casting blank prepared in Comparative Example 1 of the present invention;

[0026] Figure 4 This is a picture of another ingot prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0027] The present invention provides a method for stably controlling the shell thickness of a continuous casting crystallizer, which is characterized in that the water temperature of a cold water in the crystallizer is controlled to be below 40°C, the water inlet pressure of the cold water in the crystallizer is controlled to be above 0.8 MPa, the fluctuation of the inverted taper of the copper tube of the crystallizer is controlled to be within 0.05% / m, and the water volume of the cold water in the crystallizer is set to increase with the increase of the casting speed and the tundish temperature.

[0028] The present invention stabilizes the mold shell thickness, reduces stress concentration in the mold shell, and significantly mitigates surface cracking in the slab. The method is primarily targeted at crack-sensitive steel grades containing alloys such as niobium, vanadium, titanium, and boron, such as grades Q355E, S355ML, and C345. The specific composition contents are shown in Table 1.

[0029] Table 1 Composition content of different steel grades

[0030]

[0031] In the present invention, there is no special limitation on the model of the crystallizer, and a crystallizer of a model commonly used by those skilled in the art can be used.

[0032] The present invention preferably controls the water temperature of the crystallizer-cold water to below 40°C, more preferably 33-40°C, such as 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, and preferably a range with any of the above values ​​as the upper limit. Specifically, in winter, the present invention preferably controls the water temperature of the crystallizer-cold water to 33-35°C, and in summer, the present invention preferably controls the water temperature of the crystallizer-cold water to 38-40°C. In the present invention, the fluctuation of the inlet water temperature of the crystallizer-cold water is preferably controlled within 2°C. The present invention achieves the purpose of stabilizing the heat transfer effect of the crystallizer by stabilizing the inlet water temperature and temperature fluctuation of the cold water.

[0033] The present invention preferably controls the inlet pressure of the crystallizer's cold water to be above 0.8 MPa, more preferably 0.85-0.87 MPa, such as 0.85 MPa, 0.86 MPa, or 0.87 MPa, preferably within a range with any of the above values ​​as the upper limit. The present invention preferably controls the fluctuation of the inlet pressure of the crystallizer's cold water to be within 0.02 MPa. The present invention stabilizes the flow rate and flow rate of the cold water by controlling the pressure and pressure fluctuation of the crystallizer's cold water.

[0034] The present invention preferably controls the inverted taper of the mold copper tube to 1.20-1.25% / m, preferably 1.21-1.24% / m, such as 1.20% / m, 1.21% / m, 1.22% / m, 1.23% / m, 1.24% / m, 1.25% / m, and preferably a range value with any of the above values ​​as the upper limit; the present invention preferably controls the fluctuation of the inverted taper of the mold copper tube to within 0.05% / m, more preferably 0.04% / m. By stabilizing the inverted taper of the copper tube, the air gap between the mold copper tube and the shell is stabilized, and the heat transfer effect of the crystallizer is stabilized.

[0035] The amount of cold water in the crystallizer, the casting speed, and the tundish temperature satisfy the relationship shown in Formula I:

[0036] Q = a × V + b + c × (T-1520) Formula I;

[0037] In formula I, Q is the amount of water in the crystallizer cooling water, V is the casting speed, T is the tundish temperature, and a is (Q 最大 -B) / V 最大 , Q 最大 V is the maximum amount of cold water in the crystallizer, 最大 is the maximum billet drawing speed, b is the minimum amount of cooling water in the crystallizer, and c is between 5 and 10.

[0038] In the present invention, the tundish temperature is preferably 1520-1560°C, more preferably 1530-1550°C, such as 1520°C, 1530°C, 1540°C, 1550°C, 1560°C, preferably a range value with any of the above values ​​as the upper limit; when the tundish temperature T<1520°C, it is calculated as 1520°C, and when the tundish temperature T>1560°C, it is calculated as 1560°C.

[0039] In the present invention, the casting billet drawing speed V is preferably 0-5 m / min, more preferably 1-4 m / min, such as 0.1 m / min, 0.5 m / min, 1 m / min, 1.5 m / min, 2 m / min, 2.5 m / min, 3 m / min, 3.5 m / min, 4 m / min, 4.5 m / min, 5 m / min, preferably a range value with any of the above values ​​as the upper limit.

[0040] The coefficient a is determined by the maximum water volume of the mold cooling water at the maximum billet drawing speed when the tundish temperature is 1520℃, that is, a is (Q 最大 -B) / V 最大 , Q 最大 V is the maximum amount of cold water in the crystallizer, 最大 is the maximum casting billet pulling speed; coefficient B is the minimum water volume of the crystallizer cooling water, and the value of coefficient c is 5 to 10, such as 5, 6, 7, 8, 9, 10, preferably a range value with any of the above values ​​as the upper limit.

[0041] In the present invention, when the water volume of the crystallizer is at a minimum, the flow rate of the crystallizer cold water is preferably not less than 8-10 m / s, more preferably not less than 9 m / s. When the water volume of the crystallizer cold water is at a maximum, the flow rate of the crystallizer cold water is preferably not more than 12-14 m / s, more preferably not less than 13 m / s.

[0042] The present invention provides a method for stably controlling the shell thickness of a continuous casting mold. The method involves controlling the temperature of the mold's cooling water below 40°C, the inlet pressure of the cooling water above 0.8 MPa, and the fluctuation of the mold's copper tube taper within 0.05% / m. The amount of cooling water in the mold is configured to increase with increasing casting speed and tundish temperature. By controlling the inlet temperature and pressure of the cooling water, as well as the inlet taper of the copper tube, the invention establishes a dedicated mold primary cooling model, thereby improving the uniformity of the mold primary cooling, stabilizing the mold shell thickness, and enhancing the quality of the cast mold.

[0043] The method of the present invention has the following advantages:

[0044] 1. It can effectively solve the problem of unstable shell thickness of the continuous casting machine, realize stable control of the shell thickness of the crystallizer, and improve the surface quality of the casting.

[0045] 2. Simple design, easy to use and highly operable.

[0046] In order to further illustrate the present invention, a method for stably controlling the shell thickness of a continuous casting crystallizer provided by the present invention is described in detail below in conjunction with examples, but it should not be understood as limiting the scope of protection of the present invention.

[0047] In the following examples, the steel grade used is S355ML.

[0048] Example 1

[0049] This embodiment uses a 160*160 billet continuous casting machine crystallizer.

[0050] 1. The inlet temperature of cold water to the crystallizer is 36℃, and the inlet temperature fluctuation is controlled within 2℃.

[0051] 2. The cold water inlet pressure of the crystallizer is 0.86MPa, and the inlet pressure fluctuation is controlled within 0.02MPa.

[0052] 3. The fluctuation of the inverted taper of the crystallizer copper tube is within 0.05% / m, and the inverted taper of the crystallizer copper tube is stably controlled at 1.22% / m.

[0053] 4. When the water volume of the crystallizer is at the minimum, the water flow rate of the crystallizer is not less than 9m / s, and the minimum water volume is 1694L / min; when the water volume of the crystallizer is at the maximum, the water flow rate of the crystallizer is not more than 14m / s, and the maximum water volume is 2446L / min.

[0054] 5. A special model is used for the primary cooling of the crystallizer. The functional relationship between the amount of cooling water Q, the billet drawing speed V, and the tundish temperature T is: Q = A × V + B + C × (T-1520). The tundish temperature T is between 1520 and 1560 ° C. When the tundish temperature is <1520 ° C, it is calculated as 1520 ° C. When the tundish temperature is >1560 ° C, it is calculated as 1560 ° C.

[0055] 6. The tundish temperature coefficient C is selected as 10.

[0056] 7. Coefficient B is the minimum amount of cold water in the crystallizer. The calculated water seam area of ​​the 160*160 cross-section crystallizer is 0.000314m 2 , the minimum water flow velocity is selected as 9m / s, the minimum water volume of the crystallizer cooling water is calculated to be 1694L / min, and the coefficient B is determined to be 1694.

[0057] 8. The casting speed coefficient A is determined by the maximum water volume of the crystallizer when the tundish temperature is 1520℃ and the casting speed is the maximum (A = (Qmax-B) / Vmax). The water gap area of ​​the crystallizer with a cross section of 160*160 is calculated as 0.000314m 2, the maximum water flow velocity is selected as 13m / s, and the maximum water volume of the crystallizer cooling water is calculated to be 2446L / min; the actual maximum pulling speed of the 160*160 section is selected as 4.0m / min, then the pulling speed coefficient A=(2446-1694) / 4=188.

[0058] 9. The functional relationship between the cooling water volume Q, the casting speed V and the tundish temperature T is: Q = 188 × V + 1694 + 10 × (T-1520).

[0059] The amount of cooling water in the mold at different casting speeds and tundish temperatures is shown in Table 2:

[0060] Table 2 Amount of cold water at different casting speeds and tundish temperatures in Example 1

[0061] Group Billet casting speed, m / min Tundish temperature, ℃ Cold water flow, L / min 1 0 1520 1694 2 1 1520 1882 3 2 1526 2130 4 2.5 1525 2214 5 3 1522 2278 6 4 1520 2446 7 0 1530 1794 8 1 1530 1982 9 2 1530 2170 10 3 1530 2358 11 4 1530 2446

[0062] The cast blanks obtained from groups 1 to 10 in Example 1 are as follows: Figure 1 and Figure 2 As shown by Figure 1 and Figure 2 It can be seen that the surface quality of the ingot prepared in Example 1 of the present invention is normal, and no surface crack quality defects are found in the finishing inspection.

[0063] Example 2: Shell Thickness Stability Test

[0064] In this embodiment, the stability of the mold shell thickness is reflected by the heat removed by the cold water in the mold, mainly by judging whether the heat removed by the unit molten steel is stable under different casting speeds and tundish temperatures.

[0065] This embodiment uses a 160*160 billet continuous casting machine crystallizer.

[0066] 1. The inlet temperature of cold water in the crystallizer is 34℃, and the inlet temperature fluctuation is controlled within 2℃.

[0067] 2. The cold water inlet pressure of the crystallizer is 0.87MPa, and the inlet pressure fluctuation is controlled within 0.02MPa.

[0068] 3. The fluctuation of the inverted taper of the crystallizer copper tube is within 0.05% / m, and the inverted taper of the crystallizer copper tube is stably controlled at 1.23% / m.

[0069] 4. A special model is used for the primary cooling of the crystallizer. The functional relationship between the amount of cold water Q, the billet drawing speed V, and the tundish temperature T is: Q = 188 × V + 1694 + 10 × (T-1520). When the tundish temperature is <1520°C, it is calculated as 1520°C. When the tundish temperature is >1560°C, it is calculated as 1560°C.

[0070] 5. When the water volume of the crystallizer is at the minimum, the water flow rate of the crystallizer is not less than 9m / s, and the minimum water volume is 1694L / min; when the water volume of the crystallizer is at the maximum, the water flow rate of the crystallizer is not more than 13m / s, and the maximum water volume is 2446L / min.

[0071] The results are shown in Table 3.

[0072] Table 3 Shell thickness stability test

[0073] Group 1 2 3 Casting speed, m / min 2 2.5 3 Tundish temperature, ℃ 1526 1525 1522 Cold water flow, L / min 2130 2214 2278 Inlet and outlet water temperature difference, ℃ 5.13 6.16 7.15 Calories, J 45892980 57280608 68408340 Heat absorbed per kg of molten steel, J / Kg 115891 115718 115166

[0074] It can be seen from Table 3 that when the casting speeds are 2.0, 2.5 and 3.0 m / min, the heat absorbed by each kg of molten steel is 115891, 115718 and 115166 J / Kg, respectively. The deviation of the heat absorbed by each kg of molten steel is small, which indicates that the growth thickness of the shell of the crystallizer casting is basically stable.

[0075] Example 3

[0076] This embodiment uses a 160*160 billet continuous casting machine crystallizer.

[0077] 1. The inlet temperature of cold water to the crystallizer is 35℃, and the inlet temperature fluctuation is controlled within 2℃.

[0078] 2. The cold water inlet pressure of the crystallizer is 0.87MPa, and the inlet pressure fluctuation is controlled within 0.02MPa.

[0079] 3. The fluctuation of the inverted taper of the crystallizer copper tube is within 0.05% / m, and the inverted taper of the crystallizer copper tube is stably controlled at 1.21% / m.

[0080] 4. A special model is used for the primary cooling of the crystallizer. The functional relationship between the amount of cold water Q, the billet drawing speed V, and the tundish temperature T is: Q = 188 × V + 1694 + 10 × (T-1520). When the tundish temperature is <1520°C, it is calculated as 1520°C. When the tundish temperature is >1560°C, it is calculated as 1560°C.

[0081] 5. When the water volume of the crystallizer is at the minimum, the water flow rate of the crystallizer is not less than 9m / s, and the minimum water volume is 1694L / min; when the water volume of the crystallizer is at the maximum, the water flow rate of the crystallizer is not more than 13m / s, and the maximum water volume is 2446L / min.

[0082] 6. Group 2 is calculated according to the model with a single cooling water volume. To verify the change in heat removed at different casting speeds under the same tundish temperature and single cooling water volume conditions, the single cooling water volume and tundish temperature of Groups 1 and 3 are fixed to be the same as those of Group 2.

[0083] The amount of cold water in the crystallizer, the temperature of the tundish and the casting speed shall be in accordance with Table 4.

[0084] Table 4 Process parameters of Example 3

[0085] Group 1 2 3 Casting speed, m / min 2 2.5 3 Tundish temperature, ℃ 1525 1525 1525 Cold water flow, L / min 2214 2214 2214 Inlet and outlet water temperature difference, ℃ 5.13 6.16 6.91 Calories, J 47702844 57280608 64254708 Heat absorbed per kg of molten steel, J / Kg 120462 115718 108173

[0086] It can be seen from Table 4 that with the increase of the pulling speed, the heat carried away by the unit molten steel gradually decreases and the thickness of the crystallizer shell becomes thinner.

[0087] Example 4

[0088] This embodiment uses a 160*160 billet continuous casting machine crystallizer.

[0089] 1. The inlet temperature of cold water to the crystallizer is 35℃, and the inlet temperature fluctuation is controlled within 2℃.

[0090] 2. The cold water inlet pressure of the crystallizer is 0.87MPa, and the inlet pressure fluctuation is controlled within 0.02MPa.

[0091] 3. The fluctuation of the inverted taper of the crystallizer copper tube is within 0.05% / m, and the inverted taper of the crystallizer copper tube is stably controlled at 1.21% / m.

[0092] 4. A special model is used for the primary cooling of the crystallizer. The functional relationship between the amount of cold water Q, the billet drawing speed V, and the tundish temperature T is: Q = 188 × V + 1694 + 10 × (T-1520). When the tundish temperature is <1520°C, it is calculated as 1520°C. When the tundish temperature is >1560°C, it is calculated as 1560°C.

[0093] 5. When the water volume of the crystallizer is at the minimum, the water flow rate of the crystallizer is not less than 9m / s, and the minimum water volume is 1694L / min; when the water volume of the crystallizer is at the maximum, the water flow rate of the crystallizer is not more than 13m / s, and the maximum water volume is 2446L / min.

[0094] 6. Group 2 is calculated according to the model with a constant cold water volume. To verify the change in heat removed at different tundish temperatures under the same casting speed and constant cold water volume conditions, Groups 1 and 3 have the same cold water volume and casting speed as Group 2.

[0095] The amount of cold water in the crystallizer, the temperature of the tundish and the casting speed shall be in accordance with Table 5.

[0096] Table 5 Process parameters of Example 4

[0097] Group 1 2 3 Casting speed, m / min 2.5 2.5 2.5 Tundish temperature, ℃ 1520 1525 1530 Cold water flow, L / min 2214 2214 2214 Inlet and outlet water temperature difference, ℃ 6.23 6.16 6.12 Calories, J 57931524 57280608 56908656 Heat absorbed per kg of molten steel, J / Kg 117033 115718 114967

[0098] It can be seen from Table 5 that as the tundish temperature increases, the heat carried away by the unit molten steel gradually decreases and the thickness of the mold shell becomes thinner.

[0099] Example 5

[0100] This embodiment uses a 160*160 billet continuous casting machine crystallizer.

[0101] 1. The inlet temperature of cold water to the crystallizer is 35℃, and the inlet temperature fluctuation is controlled within 2℃.

[0102] 2. The cold water inlet pressure of the crystallizer is 0.87MPa, and the inlet pressure fluctuation is controlled within 0.02MPa.

[0103] 3. The fluctuation of the inverted taper of the crystallizer copper tube is within 0.05% / m, and the inverted taper of the crystallizer copper tube is stably controlled at 1.21% / m.

[0104] 4. A special model is used for the primary cooling of the crystallizer. The functional relationship between the amount of cold water Q, the billet drawing speed V, and the tundish temperature T is: Q = 188 × V + 1694 + 10 × (T-1520). When the tundish temperature is <1520°C, it is calculated as 1520°C. When the tundish temperature is >1560°C, it is calculated as 1560°C.

[0105] 5. When the water volume of the crystallizer is at the minimum, the water flow rate of the crystallizer is not less than 9m / s, and the minimum water volume is 1694L / min; when the water volume of the crystallizer is at the maximum, the water flow rate of the crystallizer is not more than 13m / s, and the maximum water volume is 2446L / min.

[0106] 6. Group 2 is calculated according to the model with a certain amount of cold water. To verify the change in heat removed with different amounts of cold water under the same casting speed and tundish temperature conditions, the tundish temperature and casting speed of Group 1 and Group 3 are fixed to be the same as those of Group 2.

[0107] The amount of cold water in the crystallizer, the temperature of the tundish and the casting speed shall be in accordance with Table 6.

[0108] Table 6 Process parameters of Example 6

[0109] Group 1 2 3 Casting speed, m / min 2.5 2.5 2.5 Tundish temperature, ℃ 1525 1525 1525 Cold water flow, L / min 2100 2214 2300 Inlet and outlet water temperature difference, ℃ 6.07 6.16 6.26 Calories, J 53537400 57280608 60471600 Heat absorbed per kg of molten steel, J / Kg 108156 115718 122165

[0110] It can be seen from Table 6 that as the amount of cooling water in the crystallizer increases, the heat carried away by the unit molten steel gradually increases and the thickness of the crystallizer shell becomes thicker.

[0111] Comparative Example 1

[0112] Use 160*160 billet continuous casting machine crystallizer.

[0113] 1. The inlet temperature of cold water into the crystallizer is 25℃.

[0114] 2. The cold water inlet pressure of the crystallizer is 0.92MPa.

[0115] 3. The taper of the crystallizer copper tube is 1.35% / m.

[0116] 4. When the pulling speed is 1.5-2.5m / min, the tundish temperature is 1530-1550℃, and the cooling water volume is kept constant at 2400-2500L / min.

[0117] The obtained castings are Figure 3 and Figure 4 As shown in the figure, due to the low inlet temperature of the cooling water and the large amount of cooling water, the casting speed and the temperature of the tundish fluctuate, resulting in surface cracks in the casting billet.

[0118] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for stably controlling the shell thickness of a continuous casting mold, characterized in that: The fluctuation of the inverted taper of the copper tube of the crystallizer is controlled within 0.05% / m, the water temperature of the first cooling water of the crystallizer is controlled within 33-40°C, and the fluctuation of the inlet water temperature is controlled within 2°C; the inlet water pressure of the first cooling water of the crystallizer is controlled within 0.85-0.87 MPa; The amount of cold water in the crystallizer, the casting speed, and the tundish temperature satisfy the relationship shown in Formula I: Q = a × V + b + c × (T-1520) Formula I; In formula I, Q is the amount of water in the crystallizer cooling water, V is the casting speed, T is the tundish temperature, and a is (Q 最大 -b) / V 最大 , Q 最大 V is the maximum amount of cold water in the crystallizer, 最大 is the maximum casting speed, b is the minimum water volume of the crystallizer cooling water, and c is 5~10; The casting billet drawing speed V is 1.5~5m / min, and the tundish temperature T is 1520~1560℃. When the tundish temperature T is less than 1520℃, it is calculated as 1520℃; when the tundish temperature T is greater than 1560℃, it is calculated as 1560℃.

2. The method according to claim 1, characterized in that The water temperature of the crystallizer-cold water is controlled at 33-35°C in winter and 38-40°C in summer.

3. The method according to claim 1, characterized in that The inlet pressure fluctuation of the cold water of the crystallizer is controlled within 0.02 MPa.

4. The method according to claim 1, wherein The back taper of the copper tube of the crystallizer is controlled at 1.20-1.25% / m.

5. The method according to claim 1, wherein When the water volume of the crystallizer is at the minimum, the flow rate of the cold water in the crystallizer is not less than 10 m / s; when the water volume of the cold water in the crystallizer is at the maximum, the flow rate of the cold water in the crystallizer is not more than 14 m / s.

6. The method according to any one of claims 1 to 5, characterized in that The shell is made of steel containing one or more of niobium, vanadium, titanium and boron.

7. The method according to claim 6, characterized in that The brand of the shell is Q355E, S355ML or C345.

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