Calibration method for heavy and medium plate rolling mill

Abstract

The invention relates to the technical field of steel plate rolling, in particular to a heavy and medium plate mill calibration method which comprises the following calibration steps: after zero adjustment of mill equipment is completed, main transmission is started to rotate at a preset speed; during pressurization under the hydraulic pressure, pressurization is stopped when the pressure value n of each step is increased, pressurization is continued after the supporting roller completely rotates by a circle, and pressurization is stopped until the maximum rigidity test pressure value m is increased; and according to the calibration steps, roll gap and pressure data under a constant pressure value are obtained, and under the constant pressure value, the pressure is stopped when the pressure value n of each step is increased, and the duration time for the supporting roll to completely rotate for a circle is obtained. In the calibration process, pressurization is carried out according to the step pressure, pressurization is continued after waiting for the supporting roll to completely rotate by one circle, the average roll gap and the average pressure of the rolling mill under each step pressure can be obtained, and a more accurate rolling mill rigidity curve under the current supporting roll state can be obtained through regression by means of the data and the model.

Description

Technical Field

[0001] The invention relates to the technical field of steel plate rolling, and in particular to a medium and thick plate rolling mill calibration method. Background Art

[0002] When a medium and thick plate and strip mill is in production, it is necessary to set the target roll gap for each pass in the production, and the setting accuracy of the target roll gap is directly related to the dimensional accuracy of the final product. When calculating the target roll gap, it is necessary to consider the roll gap change caused by the elastic deformation of the rolling mill, which is called bounce. Usually, the bounce is calculated using formula (1):

[0003]

[0004] In formula (1), ΔS is the rolling mill bounce, P s is the rolling force, P Cal is the zero adjustment rolling force, M s The rolling force is P s The stiffness of the rolling mill at .

[0005] The rigidity of the rolling mill is an important parameter that reflects the structural performance of the rolling mill and is the main indicator of the rolling accuracy that the rolling mill can obtain. The rigidity of the rolling mill provides the necessary equipment performance data for the preparation of new and reasonable rolling procedures, and provides data for the automatic adjustment of thickness and computer control, so determining the rigidity of the rolling mill has important practical significance.

[0006] Most medium and thick plate manufacturers complete stiffness calibration with a fixed slope, continuously from zero to the maximum pressure. This calibration process does not take into account the influence of roll eccentricity, etc., which may cause certain changes in the stiffness data of each calibration. If the roll eccentricity is large, the stiffness error will be large. Summary of the invention

[0007] In view of the above technical problems, the present invention overcomes the shortcomings of the prior art and provides a calibration method for a medium and thick plate rolling mill. During the calibration process, the pressure is increased according to the step pressure, and the pressure is stopped and waited for the support roller to make a complete rotation before continuing to increase the pressure. In this way, the maximum stiffness test pressure is reciprocated, and the average roll gap and average pressure of the rolling mill under each step pressure can be obtained. Using these data, the model can regress a more accurate rolling mill stiffness curve under the current support roller state.

[0008] The plate mill calibration method provided by the present invention comprises the following calibration steps:

[0009] After completing the zero adjustment of the rolling mill equipment, start the main drive and rotate it at the preset speed;

[0010] 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;

[0011] 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.

[0012] The technical solution further defined in the present invention is:

[0013] Furthermore, m / n=x, wherein x is a positive integer greater than 1.

[0014] Furthermore, after obtaining the roll gap and pressure data under the constant pressure value, a rolling mill stiffness curve is formed to obtain the rolling mill stiffness.

[0015] Furthermore, in the calibration step, the rolling mill linear speed is 2 m / s.

[0016] Further, in the calibration step, n is 200 tons and m is 6000 tons.

[0017] Furthermore, in the calibration step, the time for the support roller to make a complete rotation is 4 seconds.

[0018] Furthermore, the zero adjustment of the rolling mill equipment includes:

[0019] Electric pressing and hydraulic pressing return to the initial position;

[0020] Bending the roller to a balanced force state;

[0021] Electric pressing stops after reaching the rolling line position; and

[0022] Hydraulically pressed down to the roller contact position.

[0023] 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 stops.

[0024] Furthermore, 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. The model uses a general linear regression mathematical algorithm to regress a third-order stiffness curve function to calculate the stiffness of the rolling mill.

[0025] Furthermore, the third-order stiffness curve function specifically includes:

[0026] M=Km0+Km1*F+Km2*F*F+Km3*F*F*F+Km4*F*F*F*F;

[0027] Where: M is stiffness, Km0, Km1, Km2, Km3 are coefficients of the third-order function of the model, and F is pressure;

[0028] The subsequent rolling mill model uses the third-order stiffness curve function to calculate the roll gap setting value for each steel plate and each pass.

[0029] The beneficial effects of the present invention are:

[0030] (1) The plate mill calibration method provided by the present invention increases the pressure according to the step pressure during the calibration process, and stops and waits for the backup roll to rotate a full circle before continuing to increase the pressure, and thus reciprocates to the maximum stiffness test pressure, so that the average roll gap and average pressure of the mill under each step pressure can be obtained. Using these data, the model can regress a more accurate mill stiffness curve under the current backup roll state;

[0031] (2) The present invention can calculate and obtain an accurate mill roll gap value according to the set thickness of each pass and the predicted rolling force, and use these stiffness data in the production process, so as to obtain a suitable rolling schedule. According to the rolling schedule, through multiple passes of reciprocating rolling, the product accuracy is significantly improved;

[0032] (3) The present invention can provide more accurate stiffness values ​​for different pressures during each rolling pass, thereby improving the real-time adjustment accuracy of the automatic thickness compensation model during steel rolling, thereby improving the rolling plate difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of the implementation steps of the plate mill calibration method of the present invention;

[0034] Figure 2 The calibration curve of the calibration stiffness is completed continuously from zero to the maximum pressure (fixed slope);

[0035] Figure 3 It is a stiffness calibration curve diagram of the new medium and thick plate rolling mill calibration method in the embodiment of the present invention. DETAILED DESCRIPTION

[0036] When the rolling mill completes a certain rolling task, the worn support rolls will be ground offline, and the newly ground support rolls that meet the process requirements will be replaced online. The support rolls that are online will be calibrated for the rolling mill stiffness.

[0037] See also Figure 1 The plate mill calibration method provided in this embodiment specifically includes steps 1 to 21, which are basically as follows:

[0038] After the zero adjustment of the rolling mill equipment is completed, the main drive is turned on to rotate at a preset speed. The zero adjustment of the rolling mill equipment includes: electric pressing and hydraulic pressing back to the initial position, bending the roll to a balanced force state, electric pressing to the rolling line position and then stopping, and hydraulic pressing to the roll contact position;

[0039] When the 7th step of stiffness calibration is reached, the pressure is increased according to the step pressure, that is, after reaching a predetermined pressure, the AGC hydraulic cylinder is kept inactive, and the supporting roller is waited to rotate one circle (the roller rotation speed is less than 2 m / s), and the hydraulic cylinder is reactivated, and then to the next step pressure, and finally the maximum pressure of stiffness calibration is reached to complete the step stiffness calibration; specifically in this embodiment, the pressure is increased by 200t each time, and the pressure is increased again after the supporting roller rotates one complete circle. During the rotation of one circle, the program calculates the average pressure and the average roll gap and records them, completing the first step pressure process, and then the AGC hydraulic cylinder starts to press down and performs the second step pressure (400t) process, and the same action is repeated until all the step pressure processes are completed; until the pressure is increased to the maximum stiffness test pressure value of 6000t, the pressure is suspended, and after the calibration step is completed, the hydraulic pressure is returned to the rolling line position, the electric pressure is returned to the initial position, and the main transmission stops.

[0040] According to the above calibration steps, the roll gap and pressure data under constant pressure value are obtained. The constant pressure value specifically refers to the duration of stopping when the total pressure value of each step of pressurization reaches 200t and waiting for the support roll to make a complete rotation. After such calibration, the average pressure and average roll gap values ​​during one rotation of the roll after the step pressure can be obtained. These values ​​are used for stiffness calculation to eliminate the influence of roll eccentricity and the like, and the stiffness calculation result will be more accurate.

[0041] It should be noted that the parameters for step stiffness calibration in this embodiment include:

[0042] (1) The linear speed of the rolling mill during stiffness calibration is 2 m / s; (2) The number of pressure steps is 30; (3) The total pressure change in each step is 200 tons; (4) The duration of each step pressure is 4 seconds, which is the time it takes for the roller to rotate once; (5) The slope of the step pressure change is 100 tons / second.

[0043] like Figure 2 , Figure 3As shown, they are respectively the calibration stiffness calibration curve completed continuously from zero to the maximum pressure in the past and the stiffness calibration curve of this embodiment. It can be clearly seen that the actual effect of the step stiffness calibration will last for a certain period of time in each step pressure section, thereby realizing the function of the step stiffness calibration. After the application of this embodiment, more data (including: average roll gap, average pressure, speed, etc.) can be obtained under each step pressure. Using these data, the model can regress a more accurate rolling mill stiffness curve under the current support 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 to calculate the accurate rolling mill roll gap value, thereby obtaining a suitable rolling schedule. According to the rolling schedule, through multiple passes of reciprocating rolling, the product accuracy required by the customer is produced, the product thickness accuracy is significantly improved, and the product unplanned rate is reduced from 4.5% to 2.3%.

[0044] After Nangang adopted the new stiffness test method: the pressure setting accuracy of the last three passes was improved, and the average pressure setting accuracy of all specifications increased by 5%. The pressure setting accuracy of the week before the change:

[0045] Pressure setting accuracy range for the last three passes The number of passes that meet the requirements Total number of passes Number of steel plates percentage Pressure setting accuracy percentage is less than 10% 2738 3414 1138 80.20％ Pressure setting accuracy percentage is less than 5% 1984 3414 1138 58.11％ Pressure setting accuracy percentage is less than 3% 1371 3414 1138 40.16％

[0046] Pressure setting accuracy one week after the change:

[0047] Pressure setting accuracy range for the last three passes The number of passes that meet the requirements Total number of passes Number of steel plates percentage Pressure setting accuracy percentage is less than 10% 3008 3408 1136 88.26％ Pressure setting accuracy percentage is less than 5% 2213 3408 1136 64.94％ Pressure setting accuracy percentage is less than 3% 1557 3408 1136 45.69％ .

[0048] It can be understood that the embodiments of the present invention Figure 3 In the figure, the upper two curves are the actual pressure on both sides of the rolling mill during the stiffness test, and the lower two curves are the actual roll gaps on both sides of the rolling mill during the stiffness test. Figure 2 When taking 30 points of data, we just randomly take the pressure and roller gap value of a single point. Figure 3 The average pressure and roller gap value calculated in the corresponding 30 pressure steps can be taken.

[0049] After the stiffness test is completed, the program will take the data of 30 fixed points and send them to the stiffness curve calculation model. The data of the 30 points are the actual pressure and roll gap values ​​corresponding to the pressure of 200t, 400t, 600t...6000t.

[0050] The present invention can obtain the average pressure and roll gap value, thereby avoiding the situation where the roll equipment eccentricity causes inaccurate data. After the 30-point stiffness data are sent to the stiffness calculation model, the model will use a general linear regression mathematical algorithm to regress a third-order stiffness curve function:

[0051] M=Km0+Km1*F+Km2*F*F+Km3*F*F*F+Km4*F*F*F*F;

[0052] Where: M is stiffness; Km0, Km1, Km2, Km3 are the coefficients of the third-order function of the model; F is pressure.

[0053] The subsequent rolling mill model uses this stiffness function to calculate the roll gap setting value for each steel plate in each pass and realize dynamic thickness control.

[0054] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A plate mill calibration method, characterized in that: The calibration steps include the following: 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, characterized in that: The m / n=x, wherein x is a positive integer greater than 1.

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

4. The plate mill calibration method according to claim 1, characterized in that: During the calibration step, the mill line speed was 2m / 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: During the calibration step, the time for one 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 includes: Electric pressing and hydraulic pressing return to the initial position; Bending the roller to a balanced force state; 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, 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 drive stops.

9. The plate mill calibration method according to claim 1, 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. The model uses a general linear regression mathematical algorithm to regress a third-order stiffness curve function to calculate the stiffness of the rolling mill.

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

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