A method for controlling the rolling rhythm of a plurality of slabs in a plate rolling

Abstract

The application discloses a kind of thick plate rolling multi-block steel rolling rhythm control method, when steel plate specification changes, the middle blank thickness difference of two steel plates, the temperature of opening rolling and the speed of accelerated cooling are all converted into temperature unit, and then compared with the steel plate to be tapped, the end temperature of the previous steel plate before tapping is used to start calculation, and finally the temperature of the steel plate before tapping reaches the temperature of the previous steel plate that has been tapped and cooled to before tapping and rolling to control the rolling rhythm.The application solves the problem of large error caused by manual estimation when the existing thick plate rolling mill rolls multiple blocks of steel, which can improve the hourly output tonnage.

Description

Technical Field

[0001] This invention relates to thick plate rolling mill technology, and more specifically, to a method for controlling the rolling rhythm of multiple steel blocks in thick plate rolling. Background Technology

[0002] In the rolling process of thick plates, there is a situation where multiple steel plates are rolled together. This means that a batch of steel plates with the same thickness, controlled rolling temperature, and final rolling temperature are produced together. During the roughing rolling process to the intermediate cooling zone, the first steel plate is cooled before finishing rolling, the second steel plate is cooled in the intermediate cooling zone, and so on, resulting in multiple steel plates being rolled together. The existing process flow for multiple steel plate rolling is mainly: heating - descaling - roughing rolling - finishing rolling - pre-straightening - accelerated cooling - straightening. The most significant control challenge in this production process is the rhythm control technology for specification changes during multiple steel plate rolling. Currently, the method used is manual estimation based on experience. The tapping rhythm of the heating furnace in multiple steel plate rolling is generally calculated in seconds; 180 seconds means one steel plate is produced every 3 minutes. The existing manual experience method is prone to errors: sometimes a fast rhythm results in low temperature, and sometimes a slow tapping results in high temperature, wasting rolling time. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for controlling the rolling rhythm of multiple steel blocks in thick plate rolling, which solves the problem of large errors caused by manual estimation when rolling multiple steel blocks in existing thick plate rolling mills, and can increase the hourly output tonnage.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for controlling the rolling rhythm of multiple steel blocks in thick plate rolling;

[0006] When the specifications of the steel plate change, the thickness difference between the intermediate billets of the two steel plates, the temperature of the initial rolling and the speed of the accelerated cooling are all converted into temperature units and then compared with the steel plate to be tapped. The calculation starts from the end temperature of the steel plate before tapping. Finally, the steel plate before tapping is tapped is rolled after the temperature of the steel plate that has been tapped has cooled to the temperature of the previous steel plate. This is to control the rolling rhythm.

[0007] Preferably, the thickness difference of the intermediate billet is converted into temperature units as follows: 1 mm = 1 °C.

[0008] A preferred formula, calculated starting from the final temperature of the steel plate before tapping, is as follows:

[0009] A-[B2-B1]-[D2-D1]-C=A1

[0010] Where A represents the finishing temperature of the rough rolling of the previous steel plate;

[0011] A1 indicates the temperature to which the previous steel plate has cooled after being tapped out of the furnace, just as the steel is about to be tapped.

[0012] B1 indicates that the thickness of the steel is converted into temperature when the steel is being prepared for tapping in the furnace.

[0013] B2 indicates that the thickness of the previous steel plate is converted into temperature.

[0014] C represents the final cooling temperature difference between the two steel plates;

[0015] D1 represents the initial rolling temperature of the previous steel plate.

[0016] D2 indicates the initial rolling temperature when the steel is ready to be tapped from the furnace.

[0017] Ideally, if B1, B2, D1, and D2 are positive values, then subtract them from the formula.

[0018] This invention provides a rolling rhythm control method for multiple steel blocks in thick plate rolling. This method improves the rolling rhythm and the accuracy of temperature control time for multiple steel blocks, reducing the waste of time caused by low final rolling temperature and delayed tapping due to empirical methods of tapping steel blocks. First, it comprehensively integrates all influencing factors with the L2 model temperature. Simultaneously, the thickness is defined practically: the thickness for temperature control during furnace tapping is converted into temperature control for easier calculation. Furthermore, the influence of the ACC (Advanced Control Point) on the initial rolling temperature is considered, and the ACC speed is converted into a temperature-based calculation. This forms a complete calculation formula, which is convenient for practical operation. This method can increase output by 10 tons per hour by reducing errors caused by manual estimation. Adding thickness ensures continuous control, and the rolling rhythm can be increased according to different final cooling temperatures. Detailed Implementation

[0019] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with embodiments.

[0020] This invention provides a method for controlling the rolling rhythm of multiple steel blocks in thick plate rolling;

[0021] When the specifications of the steel plate change, the thickness difference between the intermediate billets of the two steel plates, the temperature of the initial rolling and the speed of the accelerated cooling are all converted into temperature units and then compared with the steel plate to be tapped. The calculation starts from the end temperature of the steel plate before tapping. Finally, the steel plate before tapping is tapped is rolled after the temperature of the steel plate that has been tapped has cooled to the temperature of the previous steel plate. This is to control the rolling rhythm.

[0022] In multi-plate steel rolling, the thickness of the first ten steel plates after rough rolling is 190mm, the starting temperature of finish rolling is 780 degrees Celsius, and the temperature after accelerated cooling is 380 degrees Celsius. After the eleventh steel plate is rough rolled, the thickness of the intermediate billet is 130mm, the starting temperature is 830 degrees Celsius, and the temperature after accelerated cooling is 420 degrees Celsius. Thus, after the tenth steel plate is tapped, the heating furnace needs to stop tapping. If tapping is not stopped, the temperature of the eleventh steel plate will drop too quickly when it reaches the start of finish rolling due to the different thickness of the intermediate billet, resulting in a temperature that is too low and cannot meet the process requirements. Therefore, if the tapping time of the eleventh steel plate is still determined manually based on the existing method after the tenth steel plate is tapped and the heating furnace is stopped, tapping too early will result in the finish rolling not meeting the process requirements, while tapping too late will result in an excessively long waiting time, affecting production output. Therefore, the rolling rhythm control method for multiple steel plates in thick plate rolling of this invention identifies the variables involved. The thickness difference between the intermediate billets of the two steel plates, the initial rolling temperature, and the acceleration cooling speed are the main factors affecting the changes in steel plate specifications. By improving the use of temperature measuring instruments in the production line, all influencing factors are converted into temperature changes, which facilitates calculation. Therefore, the thickness difference between the intermediate billets of the two steel plates is converted into temperature. For ease of calculation, it is specified that 1 mm equals 1 degree Celsius. At the same time, the acceleration cooling speed is also standardized and converted into temperature. Thus, the following calculation method can be generated:

[0023] The thickness difference between the two steel plates is 70 mm, which translates to a temperature of 70 degrees Celsius. The final cooling temperature deviation is 30 degrees Celsius, and the finishing rolling temperature deviation between the two steel plates is 50 degrees Celsius. After calculation, the total deviation between the two steel plates is 150 degrees Celsius. Subtracting the rolling end temperature of the tenth steel plate (1060 degrees Celsius), it is calculated that the tenth steel plate should be tapped from the furnace when its temperature drops to 910 degrees Celsius.

[0024] The calculation formula for the rolling rhythm control method of multiple steel blocks in thick plate rolling of the present invention is as follows:

[0025] A-[B2-B1]-[D2-D1]-C=A1

[0026] Where A represents the finishing temperature of the rough rolling of the previous steel plate;

[0027] A1 indicates the temperature to which the previous steel plate has cooled after being tapped out of the furnace, just as the steel is about to be tapped.

[0028] B1 indicates that the thickness of the steel is converted into temperature when the steel is being prepared for tapping in the furnace.

[0029] B2 indicates that the thickness of the previous steel plate is converted into temperature.

[0030] C represents the final cooling temperature difference between the two steel plates;

[0031] D1 represents the initial rolling temperature of the previous steel plate.

[0032] D2 indicates the initial rolling temperature when the steel is ready to be tapped from the furnace.

[0033] If B1, B2, D1, and D2 are positive values, then subtract them from the formula.

[0034] This invention first comprehensively combines all influencing factors with temperature, and at the same time, it converts the thickness into temperature control through actual definition: the thickness of the steel prepared for tapping in the furnace is converted into temperature control, which is convenient for calculation. It also considers the influence of ACC on the initial rolling temperature and forms a complete calculation formula for the final cooling temperature difference of the two steel pieces in ACC, which is more convenient for actual operation.

[0035] Example

[0036] The arrangement of steel billets in the furnace is shown in Table 1 below: Steel grade S400M

[0037]

[0038] The roughing rolling end temperature of the third steel plate (serial number 3 in Table 1) is 1090℃, and the ACC roller speed of the third steel plate is 0.2. According to Table 2 below, the compensation temperature is converted to 30℃.

[0039] Table 2. ACC Roller Conveyor Speed-Temperature Compensation Comparison Table

[0040] ACC roller conveyor speed (m / s) 0.2 0.25 0.3 0.4 0.45 Compensation temperature (°C) 30 25 20 15 10

[0041] The actual calculation formula is as follows:

[0042] A=1090℃, B2=191℃, B1=143℃, D2=800℃, D1=780℃, C=30℃

[0043] A1=1090-(191-143)-(800-780)-30=1090-118=970℃

[0044] The calculation based on the above formula indicates that the tapping time for the next steel plate is when the third steel plate is tapped at 970℃.

[0045] The arrangement of steel billets in the furnace is shown in Table 3 below: Steel grade S400M

[0046]

[0047]

[0048] As can be seen from Table 3 above, the intermediate billet thickness of the fourth steel plate (number 4 in Table 3) is 143mm. By increasing the intermediate billet thickness of the fourth steel plate to 191mm, a parallel thickness transition is achieved. At the same time, since the final cooling temperature of the fourth steel plate is higher than that of the third steel plate, the rolling rhythm can be increased by 0.5 minutes starting from the fifth steel plate.

[0049] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A method for controlling the rolling rhythm of multiple steel blocks in thick plate rolling, characterized in that: When the specifications of the steel plate change, the thickness difference between the intermediate billets of the two steel plates, the temperature of the initial rolling and the speed of the accelerated cooling are all converted into temperature units and then compared with the steel plate to be tapped. The calculation starts from the end temperature of the steel plate before tapping. Finally, the steel plate before tapping is tapped is rolled after the temperature of the steel plate that has been tapped has cooled to the temperature of the previous steel plate. This is to control the rolling rhythm.

2. The method for controlling the rolling rhythm of multiple steel blocks in thick plate rolling according to claim 1, characterized in that, The thickness difference of the intermediate billet is converted into temperature units as follows: 1mm = 1℃.

3. The method for controlling the rolling rhythm of multiple steel blocks in thick plate rolling according to claim 1, characterized in that, The formula for calculation, starting from the final temperature of the steel plate before tapping, is as follows: A-[B2-B1]-[D2-D1]-C=A1 Where A represents the finishing temperature of the rough rolling of the previous steel plate; A1 indicates the temperature to which the previous steel plate has cooled after being tapped out of the furnace, just as the steel is about to be tapped. B1 indicates that the thickness of the steel is converted into temperature when the steel is being prepared for tapping in the furnace. B2 indicates that the thickness of the previous steel plate is converted into temperature. C represents the final cooling temperature difference between the two steel plates; D1 represents the initial rolling temperature of the previous steel plate. D2 indicates the initial rolling temperature when the steel is ready to be tapped from the furnace.

4. The method for controlling the rolling rhythm of multiple steel blocks in thick plate rolling according to claim 3, characterized in that: If B1, B2, D1, and D2 are positive values, then subtract them from the formula.

Images