CN119281836A

CN119281836A - A calibration method for medium and thick plate rolling mill

Info

Publication number: CN119281836A
Application number: CN202411291595.0A
Authority: CN
Inventors: 单承勤; 韩德民; 王�琦; 刘自扬; 杨海涛; 朱彦博
Original assignee: Nanjing Iron and Steel Co Ltd
Current assignee: Nanjing Iron and Steel Co Ltd
Priority date: 2024-09-14
Filing date: 2024-09-14
Publication date: 2025-01-10
Anticipated expiration: 2044-09-14
Also published as: CN119281836B

Abstract

The invention relates to the technical field of steel plate rolling, in particular to a calibration method of a heavy and medium plate rolling mill, which comprises the following calibration steps of starting main transmission to rotate at a preset speed after finishing zero adjustment of rolling mill equipment, stopping pressurizing each step pressure value n under hydraulic pressure, continuing pressurizing after a supporting roll completely rotates for one circle, stopping pressurizing until the supporting roll is pressurized to a maximum rigidity test pressure value m, obtaining roll gap and pressure data under a constant pressure value according to the calibration steps, and stopping pressurizing each step pressure value n under the constant pressure value and waiting for the duration of the supporting roll completely rotating for one circle. According to the invention, the pressure is increased according to the step pressure in the calibration process, and the pressure is continuously increased after the backup roll stops waiting for complete rotation, so that the average roll gap and the average pressure of the rolling mill under each step pressure can be obtained, and by using the data, the model can return to a more accurate rolling mill stiffness curve under the current backup roll state.

Description

Calibration method of heavy and medium plate mill

Technical Field

The invention relates to the technical field of steel plate rolling, in particular to a method for calibrating a heavy and medium plate rolling mill.

Background

When the heavy and medium plate strip rolling mill is used for production, the target roll gap of each pass in the production needs to be set, and the setting precision of the target roll gap and the dimensional precision of a final product have a direct relation. When calculating the target roll gap, the roll gap variation caused by the elastic deformation of the rolling mill is considered, and the roll gap variation is called bouncing. In general, the calculation of the bounce employs equation (1):

In equation (1), Δs is mill bounce, P _s is rolling force, P _Cal is zero rolling force, and M _s is mill stiffness at rolling force P _s.

The rigidity of the rolling mill is an important parameter reflecting the structural performance of the rolling mill, and is a main index of rolling precision obtained by the rolling mill. The rigidity of the rolling mill provides necessary equipment performance data for compiling new reasonable rolling regulations and provides data for realizing automatic adjustment and computer control of the thickness, so that the rigidity of the rolling mill is determined to have important practical significance.

Most medium plate manufacturing enterprises complete rigidity calibration with fixed slope from zero to the maximum pressure without interruption, and the calibration process does not consider the influence of eccentricity of the roller and the like, so that the rigidity data calibrated each time can have certain change, and if the eccentricity of the roller is large, the rigidity error is large.

Disclosure of Invention

Aiming at the technical problems, the invention overcomes the defects of the prior art, provides a method for calibrating a heavy and medium plate mill, which is used for pressurizing according to the step pressure in the calibrating process, stopping waiting for the complete rotation of a supporting roll and continuing pressurizing again, so that the rolling mill is reciprocated to the maximum rigidity test pressure, the average roll gap and the average pressure of the rolling mill under each step pressure can be obtained, and by utilizing the data, a model can return to a more accurate rolling mill rigidity curve under the current supporting roll state.

The invention provides a method for calibrating a heavy and medium plate mill, which comprises the following calibration steps:

After finishing zero adjustment of rolling mill equipment, starting main transmission to rotate at a preset speed;

when the hydraulic pressure is pressed down for pressurization, the pressurization is stopped when each step pressure value n is pressurized, and the pressurization is continued after the supporting roller completely rotates for one circle until the pressurization reaches the maximum rigidity test pressure value m;

and obtaining roll gap and pressure data under a constant pressure value according to the calibration steps, wherein the constant pressure value specifically refers to the duration time when each step pressure value n is pressurized and the backup roll is stopped to complete one rotation.

The technical scheme of the invention is as follows:

Further, m/n=x, where x is a positive integer greater than 1.

Further, after the roll gap and the pressure data under the constant pressure value are obtained, a rolling mill stiffness curve is formed, and the rolling mill stiffness is obtained.

Further, in the calibration step, the rolling mill line speed was 2m/s.

Further, in the calibration step, n is 200 tons and m is 6000 tons.

Further, in the calibration step, the time for the complete rotation of the backup roll is 4 seconds.

Further, the rolling mill apparatus zero adjustment includes:

electric pressing and hydraulic pressing are carried out to return to the initial position;

bending the roller to a balance force state;

stopping after the electric pressing to the rolling line position, and

Hydraulic pressure is applied to the roll contact position.

Further, after the calibration step is completed, the hydraulic pressure is pressed back to the rolling line position, the electric pressure is pressed back to the initial position, and the main transmission is stopped.

Further, after roll gaps and pressure data under constant pressure values are obtained, the roll gaps and pressures corresponding to each constant pressure value are sent to a rigidity calculation model, and a general linear regression mathematical algorithm is adopted by the model to regress a 3-order rigidity curve function so as to calculate the rigidity of the rolling mill.

Further, the 3-order stiffness curve function specifically includes:

M=Km0+Km1*F+Km2*F*F+Km3*F*F*F+Km4*F*F*F*F;

Wherein M is rigidity, km0, km1, km2 and Km3 are coefficients of a model 3-order function, and F is pressure;

And (3) calculating the roll gap set value of each pass of each steel plate by adopting the 3-order stiffness curve function in a subsequent rolling mill model.

The beneficial effects of the invention are as follows:

(1) According to the method for calibrating the medium plate mill, the pressurizing is carried out according to the step pressure in the calibrating process, the pressurizing is continued after the backup roll stops waiting for complete rotation for one circle, so that the pressure is reciprocated to the maximum rigidity test pressure, the average roll gap and the average pressure of the mill under each step pressure can be obtained, and by utilizing the data, a model can return to a more accurate mill rigidity curve under the current backup roll state;

(2) According to the method, according to the set thickness of each pass and the predicted rolling force, the rigidity data are utilized in the production process, and the accurate rolling mill roll gap value can be calculated and obtained, so that a proper rolling schedule table is obtained, and according to the rolling schedule table, the accuracy of the obtained product is obviously improved through the reciprocating rolling of a plurality of passes;

(3) The invention can provide more accurate rigidity values of different pressures during each pass of rolling, thereby improving the real-time adjustment precision of an automatic thickness compensation model during rolling and further improving the same plate difference during rolling.

Drawings

FIG. 1 is a flow chart of the implementation steps of the method for calibrating a heavy and medium plate mill according to the invention;

FIG. 2 is a graph of calibration stiffness calibration from zero to pressure maximum completed without interruption (fixed slope);

FIG. 3 is a graph showing the calibration of stiffness for the new method for calibrating a heavy and medium plate mill according to an embodiment of the present invention.

Detailed Description

After the rolling mill finishes a certain rolling task, the worn supporting roller grinds the lower line, the newly ground supporting roller with the technological requirement is replaced by the upper line, and the rigidity calibration of the rolling mill is carried out on the supporting roller after the upper line.

Referring to fig. 1, the calibration method of the heavy and medium plate mill provided in this embodiment specifically includes steps 1 to 21, and is basically as follows:

after finishing the zero adjustment of the rolling mill equipment, starting the main transmission to rotate at a preset speed, wherein the zero adjustment of the rolling mill equipment comprises the steps of electrically pressing down and hydraulically pressing down to return to an initial position, bending the roll to a balanced force state, stopping after electrically pressing down to a rolling line position and hydraulically pressing down to a roll contact position;

and in the embodiment, stopping when the stiffness calibration is finished after each step pressure value is increased by 200t, continuing to boost after the supporting roll rotates for one round completely, calculating average pressure and average roll gap by a program in the time of rotating for one round, recording, namely finishing the process of the first step pressure, starting to press by the AGC hydraulic cylinder, performing the process of the second step pressure (400 t), repeating the same actions until the step pressure process of all steps is finished, stopping boosting until the maximum stiffness test pressure value is 6000t, stopping hydraulic pressing, returning to the rolling line position after the calibration step is finished, and stopping the main transmission.

According to the calibration steps, the roll gap and the pressure data under the constant pressure value are obtained, the constant pressure value specifically means the duration of stopping when the total pressure value of each step is increased by 200t and waiting for the supporting roll to rotate completely for one circle, after the calibration, the average pressure and the average roll gap value in the process of rotating the roller for one circle after the step pressure can be obtained, the rigidity calculation is carried out by utilizing the values, the influences of roller eccentricity and the like are eliminated, and the rigidity calculation result is more accurate.

It should be noted that, parameters of the step stiffness calibration in this embodiment include:

The method comprises the steps of (1) rolling mill linear speed 2m/s during rigidity calibration, (2) pressure step number of 30 steps, (3) total pressure change of each step of 200 tons, (4) duration time of each step of pressure of 4 seconds of roller rotation, and (5) slope of 100 tons/second during step of pressure change.

As shown in fig. 2 and 3, the calibration stiffness calibration curves which are completed from zero to the maximum pressure and the stiffness calibration curves of the present embodiment are respectively the previous calibration stiffness calibration curves, it is obvious that the actual effect of the step stiffness calibration can last for a certain time in each step pressure section, so as to realize the function of step stiffness calibration, and after the present embodiment is applied, more data under each step pressure can be obtained (including: average roll gap, average pressure, speed, etc.), by using the data, the model can return to a more accurate rolling mill stiffness curve under the current supporting roll state, in the production process, according to the set thickness of each pass and the predicted rolling force, the stiffness data can be used for calculating and obtaining an accurate rolling mill roll gap value, thereby obtaining a proper rolling schedule table, according to the rolling schedule table, the product precision required by a customer is generated through the reciprocating rolling of a plurality of passes, the product thickness precision is obviously improved, and the unplanned rate of the product is reduced from 4.5% to 2.3%.

Nangang adopts the new rigidity test method, the setting precision of the pressure in the last three times is improved, and the setting precision of the average pressure of all specifications is improved by 5%. The pressure setting precision of the previous week is changed:

setting precision range of last three times of pressure	Meets the number of passes	Total number of passes	Number of steel plates	Percentage of
					The percentage of the pressure setting precision is less than 10 percent	2738	3414	1138	80.20%
The percentage of the pressure setting precision is less than 5 percent	1984	3414	1138	58.11%
					The percentage of the pressure setting precision is less than 3 percent	1371	3414	1138	40.16%

Pressure setting precision of one week after modification:

setting precision range of last three times of pressure	Meets the number of passes	Total number of passes	Number of steel plates	Percentage of
					The percentage of the pressure setting precision is less than 10 percent	3008	3408	1136	88.26%
The percentage of the pressure setting precision is less than 5 percent	2213	3408	1136	64.94%
					The percentage of the pressure setting precision is less than 3 percent	1557	3408	1136	45.69%

。

It will be appreciated that in fig. 3 of the present embodiment, the upper two curves are the actual pressures on both sides of the mill during the stiffness test, and the lower two curves are the actual roll gaps on both sides of the mill during the stiffness test. In comparison with the 30-point data of fig. 2, only a single point of pressure and roll gap values are randomly taken, and the average pressure and roll gap values calculated in the corresponding 30 pressure steps can be taken in fig. 3.

After the rigidity test is completed, the program takes data of fixed 30 points and sends the data to a rigidity curve calculation model. The data at 30 points are the actual pressure and roll gap values corresponding to pressures of 200t, 400t, 600t.

The invention can obtain the average pressure and the roll gap value, thereby avoiding the condition of inaccurate data caused by eccentric roll equipment. After the stiffness data of 30 points are sent to the stiffness calculation model, the model adopts a general linear regression mathematical algorithm to regress a 3-order stiffness curve function:

M=Km0+Km1*F+Km2*F*F+Km3*F*F*F+Km4*F*F*F*F;

wherein M is rigidity, km0, km1, km2 and Km3 are coefficients of 3-order functions of the model, and F is pressure.

And calculating a roll gap set value of each pass of each steel plate by using the rigidity function in a subsequent rolling mill model, and realizing dynamic thickness control.

In addition to the embodiments described above, other embodiments of the invention are possible. All technical schemes formed by equivalent substitution or equivalent transformation fall within the protection scope of the invention.

Claims

1. A plate mill calibration method, characterized in that it comprises the following calibration steps:

After completing the zero adjustment of the rolling mill equipment, start the main drive and rotate it at the preset speed;

When increasing pressure under hydraulic pressure, stop at each step pressure value n, and continue to increase pressure after the support roller has fully rotated one circle, and stop increasing pressure when the pressure reaches the maximum stiffness test pressure value m;

According to the above calibration steps, the roller gap and pressure data under a constant pressure value are obtained, wherein the constant pressure value specifically refers to the duration of stopping when increasing the pressure at each step pressure value n and waiting for the support roller to make a complete rotation.

2 . The plate mill calibration method according to claim 1 , wherein m/n=x, wherein x is a positive integer greater than 1.

3. The plate mill calibration method according to claim 1 is characterized in that after obtaining the roll gap and pressure data under the constant pressure value, a mill stiffness curve is formed to obtain the mill stiffness.

4. The plate mill calibration method according to claim 1, characterized in that, in the calibration step, the mill linear speed is 2 m/s.

5. The plate mill calibration method according to claim 4, characterized in that, in the calibration step, n is 200 tons and m is 6000 tons.

6. The plate mill calibration method according to claim 4, characterized in that, in the calibration step, the time for a complete rotation of the support roller is 4 seconds.

7. The plate mill calibration method according to claim 1, characterized in that the zero adjustment of the rolling mill equipment comprises:

Electric pressing and hydraulic pressing return to the initial position;

Bending the roller to a state of balanced force;

Electric pressing stops after reaching the rolling line position; and

Hydraulically pressed down to the roller contact position.

8. The plate mill calibration method according to claim 1 is characterized in that after the calibration step is completed, the hydraulic pressure is pressed back to the rolling line position, the electric pressure is pressed back to the initial position, and the main transmission stops.

9. The medium and thick plate rolling mill calibration method according to claim 1 is characterized in that after obtaining the roll gap and pressure data under constant pressure values, the roll gap and pressure corresponding to each constant pressure value are sent to the stiffness calculation model, and the model adopts a general linear regression mathematical algorithm to regress a third-order stiffness curve function to calculate the rolling mill stiffness.

10. The plate mill calibration method according to claim 9, characterized in that the third-order stiffness curve function specifically comprises:

M＝Km0+Km1*F+Km2*F*F+Km3*F*F*F+Km4*F*F*F*F;

Where: M is stiffness, Km0, Km1, Km2, Km3 are coefficients of the third-order function of the model, and F is pressure;

In the subsequent rolling mill model, the third-order stiffness curve function is used to calculate the roll gap setting value for each steel plate in each pass.