Method and device for preventing longitudinal crack of slab continuous casting head slab

Abstract

The invention relates to a method and device for preventing longitudinal cracks of a slab continuous casting head slab, and belongs to the technical field of continuous casting methods and devices. According to the technical scheme, the method comprises the following steps: calculating a function relational expression between a solidification shrinkage coefficient of molten steel and a casting blank temperature and between a linear expansion coefficient of a blank shell and the casting blank temperature; predicting the temperature of a billet shell and molten steel of the continuous casting billet discharged from the crystallizer; calculating the casting blank width of the continuous casting blank at the lower opening of the crystallizer and the actual casting blank width at high temperature; the ratio of the blank shell width to the lower opening width of the crystallizer is calculated and set according to actual conditions, and when the ratio is smaller than a threshold value, an operation interface gives an alarm for adjustment. The method has the beneficial effects that the longitudinal cracks of the head blank of the continuous casting blank are prevented on line, the flame cleaning work of the casting blank due to the longitudinal cracks is avoided, the time for offline casting blank cooling and manual cold detection is shortened, the temperature loss and turnover time of the casting blank are reduced, and the labor intensity of workers and the production cost loss are reduced.

Description

Technical Field

[0001] The invention relates to a method and a device for preventing longitudinal cracking of a head billet of a slab continuous casting billet, belonging to the technical field of continuous casting methods and devices. Background Art

[0002] When the continuous casting machine is started for the first time, steels such as peritectic steel, medium carbon steel and high carbon steel often have longitudinal cracks due to the fact that the shell temperature of the continuous casting billet at the outlet of the crystallizer is too low when the continuous casting billet is started, resulting in large shrinkage of the casting billet and insufficient support for the shell of the continuous casting billet by the narrow surface of the crystallizer. Summary of the invention

[0003] The object of the present invention is to provide a method and device for preventing longitudinal cracks in the head billet of a slab continuous casting billet. By calculating the ratio of the billet shell width to the lower mouth width of the crystallizer, the temperature of the billet shell at the outlet of the crystallizer is adjusted to prevent longitudinal cracks in the continuous casting billet caused by excessive shrinkage of the billet shell, and the occurrence of longitudinal cracks in the head billet of the continuous casting billet is prevented online, and flame cleaning work of the billet due to longitudinal cracks is avoided, which reduces the time of offline billet cooling and manual cold inspection, reduces the billet temperature loss and turnover time, reduces the labor intensity of workers and production cost loss, and effectively solves the above-mentioned problems existing in the background technology.

[0004] The technical solution of the present invention is: a method for preventing longitudinal cracking of the head of a slab continuous casting billet, comprising the following steps:

[0005] (1) Data collection;

[0006] (2) Calculate the functional relationship between the solidification shrinkage coefficient of the molten steel and the linear expansion coefficient of the billet shell and the billet temperature using the molten steel composition;

[0007] (3) Predict the temperature of the shell and molten steel of the continuous casting billet out of the crystallizer based on the thermocouple measuring the temperature of the crystallizer copper plate;

[0008] (4) Calculate the width of the continuous casting billet at the bottom of the crystallizer and the actual width of the billet at high temperature;

[0009] (5) Compare the width of the blank shell in the width direction with the width of the lower mouth of the crystallizer;

[0010] (6) Calculate the ratio of the shell width to the lower opening width of the crystallizer and set it according to the actual situation. When it is less than the threshold, the operation interface will issue an alarm and make adjustments;

[0011] (7) After the shrinkage of the billet shell returns to normal, the ratio of the billet shell width to the lower mouth width of the crystallizer is calculated to be ≥ the set threshold, the alarm is canceled, and the normal process parameters are restored.

[0012] In the step (1), the data collected include the composition and temperature of the molten steel, the inverted taper and upper and lower mouth widths in the width direction of the crystallizer, the casting speed of the continuous casting machine, the cooling water flow, inlet water temperature and outlet water temperature of the crystallizer, the width dimension of the cold cast billet input at room temperature and the measurement value of the crystallizer copper plate temperature measuring thermocouple.

[0013] In the step (2), the functional relationship between the linear expansion coefficient of the billet shell and the casting temperature is α=α(t 坯壳 ).

[0014] In step (3), the temperature prediction formula is:

[0015]

[0016] Where t is temperature, s is dielectric thickness, h 等效 is the equivalent heat transfer coefficient of molten steel;

[0017] Shell thickness calculation formula: s 坯壳 =kt 0.5 , where k is the solidification coefficient and t is the cooling time of the billet.

[0018] In the step (4), the actual width of the cast billet at high temperature is

[0019] L 结晶器下口铸坯宽 =α(t 坯壳 )*L

[0020] In the formula, α(t 坯壳 ) is the functional relationship between the linear expansion coefficient of the billet shell and the casting temperature.

[0021] In the step (6), the adjustment plan includes: the continuous casting machine coordinately adjusts the cooling water volume of the crystallizer and the pulling speed of the continuous casting machine to increase the temperature of the continuous casting billet shell; or adjusts the narrow surface taper of the narrow surface crystallizer to provide support for the cast billet; or comprehensively considers the above factors to give the best plan, or manually selects the adjustment plan.

[0022] A device for preventing longitudinal cracks in the head of a slab continuous casting billet comprises a first acquisition module, a first calculation module and a first identification module, wherein the first acquisition module, the first calculation module and the first identification module are connected in sequence, the first acquisition module acquires the composition and temperature of molten steel, the inverted taper in the width direction of the crystallizer and the upper and lower mouth widths, the billet drawing speed of the continuous casting machine, the cooling water flow, the inlet water temperature and the outlet water temperature of the crystallizer, the input cold cast billet width dimension at room temperature and the measured value of the crystallizer copper plate temperature measuring thermocouple; the first calculation module calculates the actual width of the billet shell and the ratio of the billet shell width to the lower mouth width of the crystallizer; the first identification module compares the ratio of the billet shell width to the lower mouth width of the crystallizer with the actual set threshold value.

[0023] A computer device for preventing longitudinal cracks in the head of a slab continuous casting billet comprises a memory and a processor, wherein the memory is used to store a computer program and the processor is used to execute the computer program to implement the steps of a method for preventing longitudinal cracks in the head of a slab continuous casting billet.

[0024] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for preventing longitudinal cracking of a head slab of a slab continuous casting.

[0025] The beneficial effects of the present invention are as follows: by calculating the ratio of the billet shell width to the lower opening width of the crystallizer, the temperature of the billet shell at the outlet of the crystallizer is adjusted to prevent longitudinal cracks in the continuous casting billet caused by excessive shrinkage of the billet shell, online prevention of the occurrence of longitudinal cracks in the head billet of the continuous casting billet, avoiding the flame cleaning work of the billet due to longitudinal cracks, reducing the time for offline billet cooling and manual cold inspection, reducing the billet temperature loss and turnover time, and reducing the labor intensity of workers and production cost losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the present invention;

[0027] Figure 2 is a flow chart of the method of the present invention;

[0028] In the figure: crystallizer 1, crystallizer copper plate 2, crystallizer copper plate temperature measuring thermocouple 3, protective slag 4, molten steel 5, billet shell 6. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the invention implementation cases clearer, the technical solutions in the implementation cases of the present invention will be clearly and completely described below in conjunction with the drawings in the implementation cases. Obviously, the implementation cases described are only a small part of the implementation cases of the present invention, rather than all the implementation cases. Based on the implementation cases in the present invention, all other implementation cases obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] A method for preventing longitudinal cracking of a slab continuous casting head slab comprises the following steps:

[0031] (1) Data collection;

[0032] (2) Calculate the functional relationship between the solidification shrinkage coefficient of the molten steel and the linear expansion coefficient of the billet shell and the billet temperature using the molten steel composition;

[0033] (3) Predict the temperature of the shell and molten steel of the continuous casting billet out of the crystallizer based on the thermocouple measuring the temperature of the crystallizer copper plate;

[0034] (4) Calculate the width of the continuous casting billet at the bottom of the crystallizer and the actual width of the billet at high temperature;

[0035] (5) Compare the width of the blank shell in the width direction with the width of the lower mouth of the crystallizer;

[0036] (6) Calculate the ratio of the shell width to the lower opening width of the crystallizer and set it according to the actual situation. When it is less than the threshold, the operation interface will issue an alarm and make adjustments;

[0037] (7) After the shrinkage of the billet shell returns to normal, the ratio of the billet shell width to the lower mouth width of the crystallizer is calculated to be ≥ the set threshold, the alarm is canceled, and the normal process parameters are restored.

[0038] In the step (1), the data collected include the composition and temperature of the molten steel, the inverted taper and upper and lower mouth widths in the width direction of the crystallizer, the casting speed of the continuous casting machine, the cooling water flow, inlet water temperature and outlet water temperature of the crystallizer, the width dimension of the cold cast billet input at room temperature and the measurement value of the crystallizer copper plate temperature measuring thermocouple.

[0039] In the step (2), the functional relationship between the linear expansion coefficient of the billet shell and the casting temperature is α=α(t 坯壳 ).

[0040] In step (3), the temperature prediction formula is:

[0041]

[0042] Where t is temperature, s is dielectric thickness, h 等效 is the equivalent heat transfer coefficient of molten steel;

[0043] Shell thickness calculation formula: s 坯壳 =kt 0.5 , where k is the solidification coefficient and t is the cooling time of the billet.

[0044] In the step (4), the actual width of the cast billet at high temperature is

[0045] L 结晶器下口铸坯宽 =α(t 坯壳 )*L

[0046] In the formula, α(t 坯壳 ) is the functional relationship between the linear expansion coefficient of the billet shell and the casting temperature.

[0047] In the step (6), the adjustment plan includes: the continuous casting machine coordinately adjusts the cooling water volume of the crystallizer and the pulling speed of the continuous casting machine to increase the temperature of the continuous casting billet shell; or adjusts the narrow surface taper of the narrow surface crystallizer to provide support for the cast billet; or comprehensively considers the above factors to give the best plan, or manually selects the adjustment plan.

[0048] A device for preventing longitudinal cracks in the head of a slab continuous casting billet comprises a first acquisition module, a first calculation module and a first identification module, wherein the first acquisition module, the first calculation module and the first identification module are connected in sequence, the first acquisition module acquires the composition and temperature of molten steel, the inverted taper in the width direction of the crystallizer and the upper and lower mouth widths, the billet drawing speed of the continuous casting machine, the cooling water flow, the inlet water temperature and the outlet water temperature of the crystallizer, the input cold cast billet width dimension at room temperature and the measured value of the crystallizer copper plate temperature measuring thermocouple; the first calculation module calculates the actual width of the billet shell and the ratio of the billet shell width to the lower mouth width of the crystallizer; the first identification module compares the ratio of the billet shell width to the lower mouth width of the crystallizer with the actual set threshold value.

[0049] A computer device for preventing longitudinal cracks in the head of a slab continuous casting billet comprises a memory and a processor, wherein the memory is used to store a computer program and the processor is used to execute the computer program to implement the steps of a method for preventing longitudinal cracks in the head of a slab continuous casting billet.

[0050] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for preventing longitudinal cracking of a head slab of a slab continuous casting.

[0051] In practical application, the following steps are included:

[0052] Read the composition and temperature of the molten steel, the inverted taper in the width direction of the crystallizer, the upper and lower mouth widths, the casting speed of the continuous casting machine, the cooling water flow of the crystallizer, the inlet and outlet water temperatures, input the cold billet width dimension L (at room temperature), and the measured value of the crystallizer copper plate temperature measuring thermocouple.

[0053] Based on the secondary system of the continuous casting machine, the solidification shrinkage coefficient of the molten steel and the linear expansion coefficient of the shell are calculated using the molten steel composition and the functional relationship between the temperature and α=α(t 坯壳 ).

[0054] Based on the thermocouple measuring the temperature of the copper plate of the crystallizer, the temperature of the shell and the molten steel of the continuous casting billet out of the crystallizer is predicted. The temperature calculation formula is:

[0055] Where t is temperature, s is medium thickness, and h is equivalent heat transfer coefficient of equivalent molten steel.

[0056] Shell thickness calculation formula: s 坯壳 =kt 0.5 , where k is the solidification coefficient; t is the cooling time of the billet.

[0057] During the solidification process of molten steel, the temperature of the shell decreases and the thickness increases. As the depth of the molten steel increases, the static pressure of the molten steel increases. The actual width of the shell is calculated by comprehensively considering the thermal stress of the shell, the supporting force of the crystallizer and the static pressure of the molten steel.

[0058] Compare the width of the billet shell in the width direction with the width of the lower mouth of the crystallizer. Calculate the ratio of the billet shell width to the lower mouth width of the crystallizer, and set it according to the actual situation. When it is less than the threshold, the continuous casting machine coordinates to adjust the cooling water volume of the crystallizer and the casting speed of the continuous casting machine to increase the temperature of the billet shell to avoid the longitudinal cracks caused by the loss of crystallizer support due to excessive shrinkage of the billet shell at low temperature; or adjust the narrow surface taper of the crystallizer to support the billet; or comprehensively consider the above factors to give the best solution.

[0059] After the shrinkage of the billet shell returns to normal, calculate the ratio of the billet shell width to the lower mouth width of the crystallizer ≥ the set threshold, cancel the alarm, and restore normal process parameters.

Claims

1. A method for preventing longitudinal cracking of the head of a slab continuous casting billet, characterized in that The following steps are involved: (1) Data collection; (2) Calculate the functional relationship between the solidification shrinkage coefficient of the molten steel and the linear expansion coefficient of the billet shell and the billet temperature using the molten steel composition; (3) Predict the temperature of the shell and molten steel of the continuous casting billet out of the crystallizer based on the thermocouple measuring the temperature of the crystallizer copper plate; (4) Calculate the width of the continuous casting billet at the bottom of the crystallizer and the actual width of the billet at high temperature; (5) Compare the width of the blank shell in the width direction with the width of the lower mouth of the crystallizer; (6) Calculate the ratio of the shell width to the lower opening width of the crystallizer and set it according to the actual situation. When it is less than the threshold, the operation interface will issue an alarm and make adjustments; (7) After the shrinkage of the billet shell returns to normal, the ratio of the billet shell width to the lower mouth width of the crystallizer is calculated to be ≥ the set threshold, the alarm is canceled, and the normal process parameters are restored.

2. A steel plant grounding line selection method based on supervised machine learning according to claim 1, characterized in that: In the step (1), the data collected include the composition and temperature of the molten steel, the inverted taper and upper and lower mouth widths in the width direction of the crystallizer, the casting speed of the continuous casting machine, the cooling water flow, inlet water temperature and outlet water temperature of the crystallizer, the width dimension of the cold cast billet input at room temperature and the measurement value of the crystallizer copper plate temperature measuring thermocouple.

3. A method for preventing longitudinal cracking of a slab continuous casting head according to claim 1, characterized in that: In the step (2), the functional relationship between the linear expansion coefficient of the billet shell and the casting temperature is α=α(t 坯壳 ).

4. A method for preventing longitudinal cracking of a slab continuous casting head according to claim 1, characterized in that: In step (3), the temperature prediction formula is: Where t is temperature, s is dielectric thickness, h 等效 is the equivalent heat transfer coefficient of molten steel; Shell thickness calculation formula: s 坯壳 =kt 0.5 , where k is the solidification coefficient and t is the cooling time of the billet.

5. A method for preventing longitudinal cracking of a slab continuous casting head according to claim 1, characterized in that: In the step (4), the actual width of the cast billet at high temperature is L 结晶器下口铸坯宽 =α(t 坯壳 )*L In the formula, α(t 坯壳 ) is the functional relationship between the linear expansion coefficient of the billet shell and the casting temperature.

6. A method for preventing longitudinal cracking of a slab continuous casting head according to claim 1, characterized in that: In the step (6), the adjustment plan includes: the continuous casting machine coordinately adjusts the cooling water volume of the crystallizer and the pulling speed of the continuous casting machine to increase the temperature of the continuous casting billet shell; or adjusts the narrow surface taper of the narrow surface crystallizer to provide support for the cast billet; or comprehensively considers the above factors to give the best plan, or manually selects the adjustment plan.

7. A device for preventing longitudinal cracking of the head of a slab continuous casting, characterized in that: It comprises a first acquisition module, a first calculation module and a first identification module, wherein the first acquisition module, the first calculation module and the first identification module are connected in sequence, the first acquisition module acquires the composition and temperature of the molten steel, the inverted taper in the width direction of the crystallizer and the upper and lower mouth widths, the billet drawing speed of the continuous casting machine, the cooling water flow rate, the inlet water temperature and the outlet water temperature of the crystallizer, the input cold billet width dimension and the measured value of the crystallizer copper plate temperature measuring thermocouple at room temperature; the first calculation module calculates the actual width of the billet shell and the ratio of the billet shell width to the lower mouth width of the crystallizer; The first recognition module compares the ratio of the billet shell width to the lower opening width of the crystallizer with the actual set threshold.

8. A computer device for preventing longitudinal cracking of the head of a slab continuous casting, characterized in that: The method comprises a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to execute the computer program to realize the steps of a method for preventing longitudinal cracking of a head slab of a slab continuous casting.

9. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, the steps of the method for preventing longitudinal cracking of the head slab of a slab continuous casting are realized.

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