Method for lean rolling rhythm of rough rolling and intermediate rolling

Abstract

The invention provides a method for refining the rolling rhythm of rough and medium rolling, and belongs to the technical field of steel bar rolling. The rotating speed of each rolling mill is adjusted, so that the rolling mill is in a stable rolling state with minimum tension, and the standard rotating speed difference between the rolling mill and the next rolling mill in the stable rolling state is calculated; and the rotating speed of each rolling mill is adjusted again, the rotating speed difference between the rolling mill and the next rolling mill is lower than the standard rotating speed difference, the micro-heap rolling state is established, and the rolling quality and efficiency are improved. According to the method, rough rolling and intermediate rolling are dynamically adjusted based on multi-parameter cooperative control, the rolling quality and efficiency of a bar production line are improved, high-quality and high-efficiency production is achieved, and the problems of high equipment vacancy rate, large energy consumption, product size fluctuation, insufficient precision and the like caused by unstable rolling rhythm are solved.

Description

Technical Field

[0001] This invention relates to the field of steel bar rolling technology, specifically to a method for lean roughing and intermediate rolling rhythm. Background Technology

[0002] The No. 3 bar mill production line is an 18-stand continuous rolling mill. Continuous rolling follows the principle of equal flow rate per second between each stand. However, to ensure rolling stability, the roughing and intermediate mills (mills #1-#12) employ micro-tension control. Although the tension is relatively small, it still exists. Unequal flow rates between successive passes can cause tension fluctuations, thus affecting the rolling rhythm. In actual production, influenced by factors such as billet size, billet temperature, material shape control for each pass (affected by groove wear), and dynamic compensation, unreasonable micro-tension settings between stands can lead to the following problems: First, inconsistent longitudinal dimensions, with a thinner head and thicker tail, resulting in inconsistent product quality; second, the instantaneous reduction in mill speed during tension release during steel ejection causes fluctuations in the rolling rhythm, leading to a rolling time for subsequent stands exceeding that of preceding stands, i.e., a gradually increasing rolling interval, affecting the stability of the rolling rhythm and significantly restricting production efficiency.

[0003] Therefore, the present invention aims to provide a new process operation scheme to stabilize the rolling rhythm and reduce product size fluctuations, thereby achieving high-quality and high-efficiency production. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides a method for lean roughing and intermediate rolling rhythm. This invention dynamically adjusts the roughing and intermediate rolling based on multi-parameter collaborative control, improving the rolling quality and efficiency of the bar production line, achieving high-quality and high-efficiency production, and solving problems such as high equipment idle rate, high energy consumption, product size fluctuations, and insufficient precision caused by unstable rolling rhythm.

[0005] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0006] This invention provides a method for the rolling rhythm of lean roughing and intermediate rolling mills, comprising:

[0007] (1) After the billet enters the roughing mill, the current from the time the billet bites the steel to the time the next billet bites the steel is compared with the current after all the billets bite the steel. The difference between the current from the time the billet bites the steel to the time the next billet bites the steel and the current after all the billets bite the steel is taken as the tension difference between the billets.

[0008] (2) By adjusting the speed of each mill, the mill is brought into a stable rolling state with minimum tension, and the current speed of each mill is recorded as the standard speed;

[0009] (3) Calculate the standard speed difference between the rolling mill and the next rolling mill, and readjust the speed of each rolling mill so that the speed difference between the rolling mill and the next rolling mill is lower than the standard speed difference, establish the micro-piling rolling state, and improve the rolling quality and efficiency.

[0010] This invention achieves the following through dynamic optimization of current difference → establishing minimum tension benchmark → actively constructing micro-buffer layer → coordinated speed increase of the entire rolling line: a) improved tension control accuracy: tension is directly quantified through current difference feedback, replacing empirical adjustment; b) breakthrough in rolling rhythm: micro-buffer state is established to increase steel throughput without compromising stability; c) adaptability to split production line: independent offset is designed for multi-line flow rate difference to eliminate three-line difference.

[0011] Further, in step (2), the stable rolling state is: the difference between the current after the rolling mill bites the steel and the current after all rolling mills bite the steel is 0.

[0012] Furthermore, in step (3), the speed of each rolling mill is adjusted so that the speed difference between the rolling mill and the next rolling mill is less than 0-5 revolutions of the standard speed difference.

[0013] Furthermore, the mill speed is adjusted sequentially from the first mill stand onwards.

[0014] Furthermore, the roughing mill consists of 6 mill stands, and the intermediate mill consists of 6 mill stands. Starting from the first mill stand, the pass shapes of the roughing and intermediate mills are as follows: box type, square type, flat ellipse, round, flat ellipse, round, flat ellipse, round, flat roll, empty pass, flat roll, and vertical roll.

[0015] Furthermore, the method also includes controlling the heating process of the steel billet before it enters the roughing rolling mill. The control standards for the steel billet heating process are as follows:

[0016] When the billet temperature is below 300℃, the preheating section temperature should be controlled at ≤1020℃, the heating section temperature at 1130~1210℃, the soaking section temperature at 1130~1200℃, and the heating time at ≥55 min.

[0017] When the billet temperature is 300~500℃, the preheating section temperature is controlled to be ≤1020℃, the heating section temperature is controlled to be 1130~1210℃, the soaking section temperature is controlled to be 1130~1200℃, and the heating time is ≥50 min.

[0018] When the billet temperature is 500℃, the preheating section temperature should be controlled at ≤1050℃, the heating section temperature at 1120~1190℃, the soaking section temperature at 1120~1190℃, and the heating time at ≥50 min.

[0019] Furthermore, the initial rolling temperature of the roughing roll is 980~1100℃.

[0020] Further, after roughing and intermediate rolling, the mill enters the finishing mill. The finishing mill consists of 6 mill stands. The starting rolling temperature of the finishing mill is greater than or equal to 1040℃, and the finishing rolling temperature is 780~800℃.

[0021] The present invention also provides a system for the lean roughing and intermediate rolling rhythm, used to implement the method, comprising: a current detection module for detecting the current from the time each mill bites the steel to the time before the next mill bites the steel, and the current value after all mills bite the steel; a calculation module connected to the current detection module for calculating the current difference and the speed difference; and a speed adjustment module connected to the calculation module for adjusting the motor speed of the corresponding stand.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] 1. Improved rolling efficiency: This invention achieves stable control of the rolling rhythm by dynamically adjusting the roughing and intermediate rolling processes. The proportion of rolling rhythms within 1.8 seconds for each specification has increased from 60% to 80%, and the average increase in steel throughput per hour is 1.5 pieces, further improving the rolling rhythm and rolling efficiency.

[0024] 2. Breakthrough in dimensional accuracy: This invention dynamically adjusts the roughing and intermediate rolling processes to control the ellipticity of the round rolled piece from No. 8 to within 0.1, resulting in a more regular cross-sectional shape of the bar and improving the consistency and stability of subsequent products.

[0025] 3. Reduced energy consumption: This invention reduces the power consumption per ton of steel by 12%-15% through dynamic speed adjustment, thereby reducing production costs. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This invention discloses a method for improving the rolling rhythm of roughing and intermediate rolling mills, taking the production of HRB400E rebar as an example, including the following steps:

[0028] (1) Heating of steel billet:

[0029]

[0030] (2) Rolling: The steel billet after heating is square in shape, with dimensions (height × width) of 162 mm × 162 mm, and the initial rolling temperature is controlled at 980~1100℃.

[0031] After rolling begins, the current from the moment the first mill bites the steel until the next mill bites the steel is compared with the current after all mills bite the steel. The difference between the current from the moment the first mill bites the steel until the next mill bites the steel and the current after all mills bite the steel is taken as the tension difference between the mills. Starting from the first mill, the speeds of mills 1-12 are adjusted until the difference between the current from the moment the first mill bites the steel until the next mill bites the steel and the current after all mills bite the steel is zero. At this point, the mill is in a stable rolling state with minimum tension, and the current speed of each mill is recorded as the standard speed. The motor speeds for roughing and intermediate rolling types and in stable rolling states are shown in Table 1.

[0032] Table 1: Motor speeds during roughing and intermediate rolling processes and stable rolling conditions

[0033]

[0034] Starting from the first mill, the speeds of mills 1-12 are adjusted again so that the speed difference between the mill and the next mill is less than 0-5 revolutions below the standard speed difference, allowing it to enter the micro-stacking state. At this time, the speeds and speed differences of each mill stand are shown in Table 2.

[0035] Table 2: Motor speeds in various embodiments of the present invention

[0036]

[0037] As shown in Table 2 above, the production of HRB400E rebar using the method of this invention, through lean roughing and intermediate rolling, achieves a maximum increase of 2 bars per hour in steel throughput, thus improving rolling rhythm and efficiency. Furthermore, by optimizing the roughing and intermediate rolling rhythm, the ellipticity of the round rolled bars from #8 is controlled within 0.1 (compared to 0.2 before optimization), resulting in more regular cross-sectional shapes and improved consistency and stability of subsequent products, ensuring product quality. Electricity consumption per ton of steel decreases by 12%-15%, significantly reducing production costs.

[0038] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for the rhythm of lean roughing and intermediate rolling, characterized in that, include: After the billet enters the roughing mill, the current from the moment the billet bites the steel until the next billet bites the steel is compared with the current after all the billets bite the steel. The difference between the current from the moment the billet bites the steel until the next billet bites the steel and the current after all the billets bite the steel is taken as the tension difference between the billets. By adjusting the speed of each billet, the billet is brought into a stable rolling state with minimum tension, and the current speed of each billet is recorded as the standard speed. The standard speed difference between the billet and the next billet is calculated, and the speed of each billet is adjusted again so that the speed difference between the billet and the next billet is lower than the standard speed difference, thus establishing a micro-stacking rolling state and improving rolling quality and efficiency.

2. The method for lean roughing and intermediate rolling rhythm according to claim 1, characterized in that, The stable rolling state is defined as follows: the difference between the current after the rolling mill bites the steel and the current before the next rolling mill bites the steel and the current after all rolling mills have bitten the steel is 0.

3. The method for lean roughing and intermediate rolling rhythm according to claim 1, characterized in that, Adjust the speed of each rolling mill so that the speed difference between the rolling mill and the next rolling mill is less than 0-5 revolutions below the standard speed difference.

4. The method for lean roughing and intermediate rolling rhythm according to claim 3, characterized in that, The mill speed is adjusted sequentially from the first mill stand onwards.

5. The method for lean roughing and intermediate rolling rhythm according to claim 1, characterized in that, The roughing mill consists of 6 mill stands, and the intermediate mill consists of 6 mill stands. Starting from the first mill stand, the pass shapes of the roughing and intermediate mills are as follows: box type, square type, flat ellipse, round, flat ellipse, round, flat ellipse, round, flat roll, empty pass, flat roll, and vertical roll.

6. The method for lean roughing and intermediate rolling rhythm according to claim 1, characterized in that, The method further includes controlling the heating process of the steel billet before it enters the roughing rolling mill. The control standards for the steel billet heating process are as follows: When the billet temperature is below 300℃, the preheating section temperature should be controlled at ≤1020℃, the heating section temperature at 1130~1210℃, the soaking section temperature at 1130~1200℃, and the heating time at ≥55 min. When the billet temperature is 300~500℃, the preheating section temperature is controlled to be ≤1020℃, the heating section temperature is controlled to be 1130~1210℃, the soaking section temperature is controlled to be 1130~1200℃, and the heating time is ≥50 min. When the billet temperature is 500℃, the preheating section temperature should be controlled at ≤1050℃, the heating section temperature at 1120~1190℃, the soaking section temperature at 1120~1190℃, and the heating time at ≥50 min.

7. The method for lean roughing and intermediate rolling rhythm according to claim 1, characterized in that, The initial rolling temperature of the roughing mill is controlled to be 980~1100℃.

8. The method for lean roughing and intermediate rolling rhythm according to claim 1, characterized in that, After roughing and intermediate rolling, the mill enters the finishing mill. The finishing mill consists of 6 mill stands. The starting rolling temperature of the finishing mill is greater than or equal to 1040℃, and the finishing rolling temperature is 780~800℃.

9. A system for the rhythm of lean roughing and intermediate rolling mills, used to implement the method described in any one of claims 1-8, characterized in that, include: The current detection module is used to detect the current from the time each rolling mill bites the steel to the time before the next rolling mill bites the steel, and the current value after all rolling mills bite the steel. A calculation module, connected to the current detection module, is used to calculate the current difference and the speed difference; The speed adjustment module, connected to the calculation module, is used to adjust the motor speed of the corresponding frame.

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