Precise control method for controlled cooling temperature of steel plate with specification of 19-21 mm of pilot mill

Abstract

The invention discloses a method for accurately controlling the cooling control temperature of a steel plate with the specification of 19-21 mm for a pilot mill. The method comprises the following steps: 1) ensuring that the ratio of the length of the steel plate to the length of an effective cooling area is 1.2: (2-5); (2) it is guaranteed that the ratio of the temperature difference value to the total water amount is equal to 2.5-2.8, and meanwhile the requirement that the total water amount of the upper collecting pipe is 4-6 m < 3 > / h smaller than the total water amount of the lower collecting pipe is met; (3) the speed of the controlled cooling rail is calculated according to the needed cooling speed; the calculation basis is that the controlled cooling rail speed = temperature difference / cooling rate; the temperature difference is equal to the final rolling temperature-the final cooling temperature; and (4) it is guaranteed that the spraying width reaches 320 mm when water flow impacts the steel plate, and the height of a nozzle is adjusted by adjusting a motor. According to the method, a front-section centralized and rear-section dispersed cooling mode is adopted, and the cooling control temperature can be more accurately controlled by reasonably setting parameters such as the flow of each group, the roller way speed, the spacing of each group and the height of the laminar cooling nozzles.

Description

Technical Field

[0001] This invention belongs to the field of steel rolling temperature process control technology, and particularly relates to a method for precise control of cooling temperature of 19mm-21mm steel plates in a pilot rolling mill. Background Technology

[0002] Currently, pilot-scale rolling mills typically employ laminar flow cooling when controlling the cooling of steel plates with a thickness of 19mm-21mm. Due to the relatively thick steel plates, significant temperature reversion occurs after heat exchange between the steel plate and the cooling water. Inaccurate final cooling temperatures are often caused by improper settings of parameters such as cooling water volume and roller speed. This patent utilizes a front-end centralized + rear-end decentralized cooling mode to effectively control the steel plate's reversion temperature. Furthermore, by rationally setting parameters such as flow rate, roller speed, and distance from the upper and lower nozzles to the steel plate for each group, the cooling temperature can be controlled more effectively and precisely.

[0003] Application No. 201911200566.8 discloses a method for controlling the uniformity of cooling temperature after rolling of medium and heavy plates in an ultra-fast cooling system. This invention provides a method for controlling the uniformity of cooling temperature after rolling of medium and heavy plates in an ultra-fast cooling system. The method involves cooling steel plates in an ultra-fast cooling system and configuring head and tail shielding with different distances and degrees for steel plates of different thicknesses to ensure temperature uniformity along the length of the steel plate. This invention selects different shielding methods according to the steel plate thickness. The ultra-fast cooling equipment automatically activates the shielding during the cooling process for cooling control. Combined with a reasonable cooling procedure, this results in uniform temperature of the steel plate, avoiding problems such as steel plate warping and uneven performance, reducing steel plate straightening costs, and ensuring the stability of the steel plate.

[0004] Application No. 201810875684.8 discloses an automatic control method for a hot-rolled strip steel post-rolling two-stage cooling process with hot head and hot tail. This control method consists of two parts: the development of hot head and hot tail control technology and the matching technology between the hot head / hot tail and the post-rolling two-stage cooling model. The former is mainly achieved through the development of hot head / hot tail setting models, feedforward models, feedback models, and self-learning models; the latter is achieved by embedding the hot head / hot tail control model into the post-rolling two-stage cooling setting model, feedforward model, feedback model, and self-learning model. This invention's automatic control method, by combining the developed hot head / hot tail control model with the hot-rolled post-rolling two-stage cooling control model, realizes a two-stage cooling process plus a hot head / hot tail cooling process for hot-rolled strip steel, providing a technological foundation for high-precision automated rolling of steel grades such as dual-phase steel, high-strength steel, and multiphase steel.

[0005] Application No. 201710425776.1 discloses a control system and method for post-rolling cooling of hot-rolled steel plates. This system achieves effective integration between various levels of control systems through a rapid post-rolling cooling process control system for hot-rolled steel plates, realizing a rapid post-rolling cooling process for hot-rolled steel plates that ensures product quality meets standard requirements. This invention enables online rapid post-rolling cooling of hot-rolled steel plates, saving energy consumption, reducing production costs, and improving production efficiency while meeting production process requirements. The process control system connects the rapid cooling equipment with other equipment on the rolling line, achieving automated control and information communication. Summary of the Invention

[0006] To overcome the problem of excessively concentrated cooling of 19mm-21mm steel plates in pilot mills, which leads to excessively low and inaccurate cooling control and makes the steel plates prone to bending, the present invention aims to provide a precise cooling control method for 19mm-21mm steel plates in pilot mills. This method adopts a front-end concentrated cooling + rear-end decentralized cooling mode, and by reasonably setting parameters such as the flow rate of each group, the speed of the roller table, the spacing between each group, and the height of the laminar flow cooling nozzles, the cooling control temperature can be controlled more precisely.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] This invention discloses a method for precise control of cooling temperature of 19mm-21mm steel plates in a pilot rolling mill, comprising:

[0009] 1) Based on the length of the experimental steel plate and the cooling control device, and with a spacing of 700mm between the two sets of cooling nozzles, determine the number of cooling valve groups to be opened and the length of the effective cooling area; ensure that the ratio of the length of the steel plate to the length of the effective cooling area is 1.2:(2-5);

[0010] 2) Adjust the valve group flow rate according to the controlled cooling temperature difference range to ensure that the temperature difference / total water volume is within the range of 2.5-2.8, while also ensuring that the total water volume of the upper manifold is less than the total water volume of the lower manifold by 4-6 m³. 3 / h, to ensure the flatness requirement of the steel plate;

[0011] 3) Calculate the controlled cooling track speed according to the required cooling rate; the calculation basis is: controlled cooling track speed = temperature difference / cooling rate; temperature difference = final rolling temperature - final cooling temperature;

[0012] 4) Based on the cooling requirements of the steel plate size, ensure that the water flow impacts the steel plate and the spray width reaches 320mm, and adjust the height of the nozzle by adjusting the motor.

[0013] Furthermore, the process requirements are as follows: the steel ingot is rolled into a 20mm thick steel plate according to the rolling process, the final rolling temperature of the steel plate is 790℃±15℃, the controlled cooling final cooling temperature is 560℃±20℃, and the cooling rate is 50℃ / s.

[0014] Furthermore, the length of the 20mm thick steel plate rolled from the steel ingot is 1100mm-1300mm; according to the 1200mm steel plate size and the 1.2:3 ratio rule, the effective cold zone length is determined to be 3000mm. Based on the effective distance of the valve group of 700mm, 4 sets of cold control valve groups are opened in the pilot mill's cold control device, with 3 sets of valves opened at the front and 1 set of valves opened at the rear.

[0015] Furthermore, the cooling water volume was determined according to the controlled cooling temperature difference requirement, with a controlled cooling process temperature difference of 230℃ for the experimental steel ingot; based on a temperature difference / total water volume ratio of 2.5, the water volume of the four groups of controlled cooling systems in the pilot mill was adjusted to 92m³. 3 / h, following the principle of centralized water flow at the front end and uniform water distribution at the rear end, the front-end cooling device is divided into 3 groups, with the first group having an upper manifold flow rate of 12m³ / h. 3 / h, the flow rate of the first group of lower manifolds is 14m³ / h. 3 / h; Second group upper manifold flow rate 12m³ / h; 3 / h, the flow rate of the second group of lower manifolds is 14m³ / h. 3 / h; the flow rate of the third group's upper manifold is 12m³ / h. 3 / h, the flow rate of the third group of lower manifolds is 14m³ / h. 3 / h; One set of rear cooling unit, upper manifold flow rate 7m³ / h. 3 / h, lower manifold flow rate 7m³ 3 / h.

[0016] Furthermore, the speed of the controlled cooling roller conveyor is set according to the cooling rate requirement of 50℃ / s. Based on 230℃÷50℃ / s=4.6s, the time for the steel plate to pass through the cooling zone is 4.6s. Calculated based on the opening of 4 sets of cooling valves, the effective opening area length of the cooling valve set is 2.8m. Based on 2.8m÷4.6s=0.608m / s, the speed of the controlled cooling roller conveyor is set to 0.608m / s.

[0017] Furthermore, adjust the distance between the cooling valve assembly nozzles and the steel plate by 300mm-400mm according to the steel plate thickness specifications to ensure the flatness and uniformity of the steel plate.

[0018] Furthermore, it is applicable to precise control of cooling temperature for hot-rolled steel plates with a width not exceeding 400mm and a specification of 19mm-21mm.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0020] The method of this invention effectively solves the problem of inaccurate cooling temperature control for 19mm-21mm thick steel plates in pilot rolling mills, and provides strong support for the development of medium and heavy steel plates. Detailed Implementation

[0021] A method for precisely controlling the cooling temperature of 19mm-21mm steel plates in a pilot rolling mill includes:

[0022] A centralized front-end cooling mode combined with a decentralized rear-end cooling system is adopted. Steel plates with a thickness of 19mm-21mm enter the controlled cooling device for controlled cooling. The steel plates are cooled to near the target temperature at the front end of the device, and then the return temperature is effectively controlled at the rear end. Taking the laboratory steel ingot rolling and controlled cooling process requirements as an example, the process requirements are as follows: the steel ingot is rolled to a 20mm thick steel plate according to the rolling process; the final rolling temperature of the steel plate is 790℃±15℃; the final controlled cooling temperature is 560℃±20℃; and the cooling rate is 50℃ / s. The specific settings for the controlled cooling parameters are as follows:

[0023] 1. First, the length of the 20mm thick steel plate rolled from the steel ingot is approximately 1100mm-1300mm. Based on the 1200mm steel plate size and the 1.2:3 ratio rule, the effective cooling zone length is determined to be 3000mm. According to the effective distance of the valve group of 700mm, 4 sets of cooling control valve groups are opened in the pilot mill's cooling control device, with 3 sets of valves opened at the front and 1 set of valves opened at the rear.

[0024] 2. The cooling water volume was determined according to the controlled cooling temperature difference requirement. The temperature difference for the controlled cooling process of the experimental steel ingot was 230℃. Based on a temperature difference / total water volume ratio of 2.5, the water volume of the four groups of controlled cooling systems in the pilot mill was adjusted to 92m³. 3 / h, following the principle of centralized water flow at the front end and uniform water distribution at the rear end, the front-end cooling device is divided into 3 groups, with the first group having an upper manifold flow rate of 12m³ / h. 3 / h, the flow rate of the first group of lower manifolds is 14m³ / h. 3 / h; Second group upper manifold flow rate 12m³ / h; 3 / h, the flow rate of the second group of lower manifolds is 14m³ / h. 3 / h; the flow rate of the third group's upper manifold is 12m³ / h. 3 / h, the flow rate of the third group of lower manifolds is 14m³ / h. 3 / h; One set of rear cooling unit, upper manifold flow rate 7m³ / h. 3 / h, lower manifold flow rate 7m³ 3 / h.

[0025] 3. Set the speed of the controlled cooling roller conveyor according to the cooling rate requirement. The cooling rate requirement is 50℃ / s. According to 230℃÷50℃ / s=4.6s, that is, the time for the steel plate to pass through the cooling zone is 4.6s. Based on the calculation of opening 4 sets of cooling valve groups, the effective length of the opening area of ​​the cooling valve group is 2.8m. According to 2.8m÷4.6s=0.608m / s, set the speed of the controlled cooling roller conveyor to 0.608m / s.

[0026] 4. Adjust the distance between the cooling valve assembly nozzle and the steel plate to 300mm-400mm according to the steel plate thickness specifications to ensure the flatness and uniformity of the steel plate.

[0027] The conventional process parameters for the cooling unit are based on the entire controlled cooling area, using a process computer model to determine the water flow, number of valves opened, and roller speed. However, it does not adjust the distance between the nozzles and the steel plate. For example, in a rolling process producing a 20mm thick steel plate with a final rolling temperature of 790℃±15℃, a controlled cooling final cooling temperature of 560℃±20℃, and a cooling rate of 50℃ / s, the conventional process parameters would involve a water flow rate of 95.6m³. 3 / h; 4 sets of valves are opened for even water distribution, with sets 2, 4, 6, and 8 opened respectively; the roller conveyor speed is set to 0.55m / s. Actual controlled cooling final cooling temperature: 470℃. Using the controlled cooling process of this patent, the controlled cooling final cooling temperature is: 568℃.

[0028] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for precisely controlling the controlled cooling temperature of a 19mm-21mm gauge steel plate in a pilot rolling mill, characterized by: Comprise: 1) According to the experimental steel plate and the length of the controlled cooling device, the number of open cooling valve groups and the length of the effective cooling area are determined according to the distance between two groups of cooling nozzles of 700mm; Ensure that the ratio of the length of the steel plate to the length of the effective cooling area is 1.2:(2-5); 2) According to the temperature difference interval of controlled cooling, adjust the valve group flow to ensure that the temperature difference / total water quantity = 2.5-2.8 interval, while meeting the requirement that the total water quantity of the upper header is less than that of the lower header by 4-6 m / h, to ensure the flatness requirement of the steel plate; 3 / h, ensure the flatness requirement of the steel plate; 3) According to the required cooling rate, the controlled cooling track speed is calculated; The calculation basis is: controlled cooling track speed = temperature difference / cooling rate; temperature difference = final rolling temperature-final cooling temperature; 4) According to the cooling requirements of the steel plate size, ensure that the water flow impact on the steel plate spraying width reaches 320mm, and adjust the nozzle height by adjusting the motor.

2. The method according to claim 1, wherein the pilot rolling mill 19mm-21mm gauge steel plate controlled cooling temperature precision control method is characterized by: The process requirements are as follows: the ingot is rolled into 20mm thick steel plate according to the rolling process, the final rolling temperature of the steel plate is 790℃±15℃, the final cooling temperature of the controlled cooling is 560℃±20℃, and the cooling rate is 50℃ / s.

3. The method according to claim 2, wherein the pilot rolling mill 19mm-21mm gauge steel plate controlled cooling temperature precision control method is characterized by: The length of the ingot rolled into 20mm thick steel plate is 1100mm-1300mm; according to the size of the steel plate of 1200mm, the effective cooling zone length is determined to be 3000mm according to the ratio of 1.2:3, and according to the effective distance of the valve group of 700mm, 4 groups of controlled cooling valve groups are opened in the pilot rolling mill controlled cooling device, 3 groups of valves are opened in the front section, and 1 group of valves is opened in the rear end.

4. The method according to claim 3, wherein the pilot rolling mill 19mm-21mm gauge steel plate controlled cooling temperature precision control method is characterized by: The cooling water quantity is determined according to the temperature difference control requirement, the temperature difference control process of the experimental steel ingot is 230 DEG C; according to the temperature difference / total water quantity=2.5, the 4-group water quantity adjustment of the pilot rolling mill control cooling is 92m 3 / h, according to the water quantity principle of front-end concentration+rear-end uniform distribution, the front-end cooling device is distributed into 3 groups, the first group upper header flow is 12m 3 / h, the first group lower header flow is 14m 3 / h; the second group upper header flow is 12m 3 / h, the second group lower header flow is 14m 3 / h; the third group upper header flow is 12m 3 / h, the third group lower header flow is 14m 3 / h; the rear-end cooling device is 1 group, the upper header flow is 7m 3 / h, the lower header flow is 7m 3 / h.

5. The method according to claim 4, wherein the pilot rolling mill 19mm-21mm gauge steel plate controlled cooling temperature precision control method is characterized by: According to the cooling rate requirement, the controlled cooling roller speed is set, the cooling rate requirement is 50℃ / s, according to 230℃÷50℃ / s=4.6s, that is, the steel plate passes through the cooling area time is 4.6s, according to the opening of 4 groups of cooling valve groups, the effective length of the cooling valve group opening area is 2.8m, according to 2.8m÷4.6s=0.608m / s, the controlled cooling roller speed is set to 0.608m / s.

6. The method according to claim 5, wherein the pilot rolling mill 19mm-21mm gauge steel plate controlled cooling temperature precision control method is characterized by: According to the thickness specification of the steel plate, adjust the distance between the cooling valve group nozzle and the steel plate to 300mm-400mm to ensure the flatness and uniformity of the steel plate.

7. The method according to claim 2, wherein the pilot rolling mill 19mm-21mm gauge steel plate controlled cooling temperature precision control method is characterized by: It is suitable for precise control of the controlled cooling temperature of 19mm-21mm specification steel plate with a hot rolled plate width of not more than 400mm.