A method for calibrating a plate mill

Abstract

The present application relates to the technical field of steel plate rolling, in particular to a kind of plate mill calibration method, comprising the following calibration steps: after completing mill equipment zero adjustment, open main drive to rotate at preset speed;When hydraulic press-down pressurization, stop when pressurizing each step pressure value n, after supporting roller complete rotation one week, continue pressurization again, until pressurization to maximum stiffness test pressure value m, pause pressurization;According to the roll gap and pressure data under constant pressure value obtained according to the above calibration steps, the duration under constant pressure value specifically refers to the duration when stopping pressurizing each step pressure value n and waiting for supporting roller complete rotation one week.The present application pressurizes according to step pressure during calibration process, and after stopping and waiting for supporting roller complete rotation one week, continue pressurization, the average roll gap and average pressure of mill under each step pressure can be obtained, using these data, model can regress more accurate mill stiffness curve under current supporting roller state.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel plate rolling, in particular to a method for calibrating a plate mill. BACKGROUND

[0002] In the production of a plate mill, the target roll gap of each pass in the production needs to be set, and the setting precision of the target roll gap is directly related to the size precision of the final product. When calculating the target roll gap, the roll gap variation caused by the elastic deformation of the mill, referred to as the springback, needs to be considered. Generally, the springback is calculated using formula (1):

[0003]

[0004] In formula (1), ΔS is the mill springback, P s is the rolling force, P Cal is the zero-adjusted rolling force, M s is the mill stiffness when the rolling force is P s .

[0005] The mill stiffness is an important parameter reflecting the structural performance of the mill and is the main index of the rolling precision that the mill can achieve. The mill stiffness provides necessary equipment performance data for compiling a new and reasonable rolling schedule and provides data for realizing the automatic adjustment of the thickness and computer control, so it is of great practical significance to determine the stiffness of the mill.

[0006] Most plate production enterprises complete the stiffness calibration from zero to the maximum pressure value without interruption with a fixed slope, and this calibration process does not consider the influence of the roll eccentricity, etc., which may cause the stiffness data calibrated each time to have a certain change, and if the roll eccentricity is large, the stiffness error will be large. SUMMARY

[0007] The present application aims at the above technical problems, overcomes the shortcomings of the prior art, and provides a method for calibrating a plate mill, which increases the pressure in steps in the calibration process, and after waiting for the complete rotation of the backup roll for one round, the pressure is continued to increase, and this is repeated until the maximum stiffness test pressure value m is reached, so that the average roll gap and the average pressure of the mill under each step pressure value n can be obtained. Using these data, the model can regress a more accurate mill stiffness curve under the current backup roll state.

[0008] The method for calibrating a plate mill provided by the present application comprises the following calibration steps:

[0009] After the zero adjustment of the mill equipment is completed, the main drive is started to rotate at a preset speed;

[0010] When the hydraulic pressure is increased, the pressure is stopped at each step pressure value n, and after the complete rotation of the backup roll for one round, the pressure is continued to increase until the maximum stiffness test pressure value m is reached, and the pressure is paused.

[0011] The roll gap and pressure data under the constant pressure value are obtained according to the calibration steps, and the constant pressure value specifically refers to the duration of stopping and waiting for the supporting roller to complete one rotation when the pressure of each step is increased by n.

[0012] The further defined technical solutions of the present application are:

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

[0014] Further, 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] Further, 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] Further, in the calibration step, the time for the supporting roller to complete one rotation is 4 seconds.

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

[0019] Electric screwdown and hydraulic screwdown back to the initial position;

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

[0021] Stopping after electric screwdown to the rolling line position; and

[0022] Hydraulic screwdown to the rolling roller contact position.

[0023] Further, after the calibration step is completed, the hydraulic screwdown is returned to the rolling line position, the electric screwdown is returned to the initial position, and the main drive is stopped.

[0024] Further, after obtaining the roll gap and pressure data under the constant pressure value, the corresponding roll gap and pressure under each constant pressure value are sent to a stiffness calculation model, the model uses a general linear regression mathematical algorithm, and a 3-order stiffness curve function is regressed to calculate the rolling mill stiffness.

[0025] Further, the 3-order stiffness curve function specifically includes:

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

[0027] Wherein: M is the stiffness, Km0, Km1, Km2, Km3 are the coefficients of the 3-order function of the model, and F is the pressure.

[0028] The subsequent rolling mill model uses the 3-order stiffness curve function to calculate the roll gap setting value of each slab and each pass.

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

[0030] (1) The medium plate rolling mill calibration method provided by the present application increases the pressure in steps during the calibration process, and stops waiting for the backup roll to complete one full rotation before continuing to increase the pressure, and this is repeated to the maximum stiffness test pressure, so that the average roll gap and average pressure of the rolling mill under each step pressure can be obtained, and using these data, the model can regress a more accurate rolling mill stiffness curve under the current backup roll state;

[0031] (2) The present application can obtain accurate rolling mill roll gap values according to the set thickness of each pass and the predicted rolling force, so as to obtain a suitable rolling schedule table, and the precision of the product obtained by repeated rolling in multiple passes is significantly improved according to the rolling schedule table;

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

[0033] Figure 1 The flow chart of the implementation steps of the medium plate rolling mill calibration method of the present application;

[0034] Figure 2 The calibration stiffness calibration curve diagram of the past uninterrupted completion from zero to the maximum pressure (fixed slope);

[0035] Figure 3 The stiffness calibration curve diagram of the new medium plate rolling mill calibration method in the embodiment of the present application. DETAILED DESCRIPTION

[0036] When the rolling mill completes a certain rolling task, the worn backup roll will be removed for grinding, and the newly ground backup roll that meets the process requirements will be replaced online, and the backup roll after being put online will be calibrated for rolling mill stiffness.

[0037] Referring to Figure 1 The medium plate rolling mill calibration method provided by the present embodiment specifically includes the first step to the twenty-first step, and is basically as follows:

[0038] After completing the zero adjustment of the rolling mill equipment, the main drive is started to rotate at a preset speed, and the zero adjustment of the rolling mill equipment includes: electric screwdown and hydraulic screwdown back to the initial position, bending roll to the balanced force state, electric screwdown to the rolling line position and stop, and hydraulic screwdown to the roll contact position;

[0039] When the step 7 of the stiffness calibration is reached, the pressure is increased according to the step pressure, that is, after reaching a certain pressure, the AGC hydraulic cylinder is kept inaction, waiting for the supporting roller to rotate one round (the roller rotation speed is less than 2 m / s), the hydraulic cylinder is reactivated, and then the next step pressure is reached, finally the maximum pressure of the stiffness calibration is reached, and the step stiffness calibration is completed; in the embodiment, the pressure is increased by 200 t for each step, and the increasing is stopped after the supporting roller rotates one round, then the increasing is continued, during the one round rotation, the average pressure and the average roll gap are calculated and recorded, that is, the first step pressure process is completed, then the AGC hydraulic cylinder starts to press down, the second step pressure (400 t) process is carried out, and the same action is repeated until the step pressure process of all steps is completed; when the pressure is increased to the maximum stiffness test pressure value 6000 t, the increasing is stopped, after the calibration step is completed, the hydraulic press down returns to the rolling line position, the electric press down returns to the initial position, and the main transmission is stopped.

[0040] According to the above calibration steps, the roll gap and pressure data under the constant pressure value are obtained, and the constant pressure value specifically refers to the duration of stopping and waiting for the supporting roller to rotate one round when the total pressure of each step is increased by 200 t; after the calibration, the average pressure and the average roll gap value during the one round rotation of the roller after the step pressure are obtained, and the stiffness calculation is carried out by using the values, so that the influences of the roller eccentricity and the like are eliminated, and the stiffness calculation result will be more accurate.

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

[0042] (1) the mill line speed is 2 m / s during the stiffness calibration; (2) the step number of the pressure step is 30 steps; (3) the total pressure change of each step is 200 t; (4) the duration of each step pressure is 4 seconds of the roller rotation one round; (5) the slope of the step pressure change is 100 t / s.

[0043] As Figure 2 , Figure 3As shown, the calibration rigidity calibration curve of the prior art is shown from zero to the maximum pressure without interruption, and the rigidity calibration curve of the embodiment is shown, and it can be obviously seen that the actual effect of the stepped rigidity calibration is that each stepped pressure section will last for a certain time, thereby realizing the function of the stepped rigidity calibration. After the embodiment is used, more data (including: average roll gap, average pressure, speed, etc.) at each stepped pressure can be obtained. Using the data, the model can regress a more accurate rolling mill rigidity curve under the current backup roll state. In the production process, according to the set thickness of each pass and the predicted rolling force, the rigidity data can be used to calculate the accurate rolling mill roll gap value, so that the appropriate rolling schedule table is obtained. According to the rolling schedule table, through multiple passes of reciprocating rolling, the product precision required by the customer is generated, and the product thickness precision is obviously improved, and the product unplanned rate is reduced from 4.5% to 2.3%.

[0044] After the new rigidity test method is used in Nangang, the pressure setting accuracy of the last three passes is improved, and the average pressure setting accuracy of all specifications is improved by 5%. The pressure setting accuracy before the change:

[0045] Range of pressure setting accuracy for last three passes Number of passes meeting the requirement Total number of passes Number of steel plate blocks Percentage Percentage of pressure setting accuracy less than 10% 2738 3414 1138 80.20％ Percentage of pressure setting accuracy less than 5% 1984 3414 1138 58.11％ Percentage of pressure setting accuracy less than 3% 1371 3414 1138 40.16％

[0046] The pressure setting accuracy after the change:

[0047] Range of pressure setting accuracy for last three passes Number of passes meeting the requirement Total number of passes Number of steel plate blocks Percentage Percentage of pressure setting accuracy less than 10% 3008 3408 1136 88.26％ Percentage of pressure setting accuracy less than 5% 2213 3408 1136 64.94％ Percentage of pressure setting accuracy less than 3% 1557 3408 1136 45.69％ .

[0048] It can be understood that the rigidity test method of the embodiment of the present application Figure 3 The upper two curves are the actual pressures on both sides of the rolling mill during the rigidity test process, and the lower two curves are the actual roll gaps on both sides of the rolling mill during the rigidity test process. Figure 2 When the data of 30 points are taken, only the pressure and roll gap value of a single point are randomly taken, Figure 3 The average pressure and roll gap value corresponding to the 30 pressure steps can be taken.

[0049] After the rigidity test is completed, the program takes the data of 30 fixed points and sends them to the rigidity curve calculation model. The data of 30 points are the actual pressure and roll gap value corresponding to the pressure of 200t, 400t, 600t...6000t.

[0050] The present application can obtain the average pressure and roll gap value, thereby avoiding the situation that the data is not accurate due to the eccentricity of the rolling mill equipment. After the rigidity data of 30 points are sent to the rigidity calculation model, the model will use a general linear regression mathematical algorithm to regress a 3-order rigidity curve function:

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

[0052] Where: M is the stiffness; Km0, Km1, Km2, Km3 are the coefficients of the model 3 order function; F is the pressure.

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

[0054] In addition to the above embodiments, the present application can have other implementation manners. Any technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope of the present application.

Claims

1. A calibration method for a medium-thick plate rolling mill, characterized in that, The calibration steps include the following: After the rolling mill equipment has been zero-adjusted, the main drive is started to rotate at the preset speed; When hydraulic pressure is increased, the pressure is stopped at each step of pressure value n, and the pressure is increased again after the support roller has rotated one full revolution, until the pressure reaches the maximum stiffness test pressure value m, at which point the pressure increase is stopped. Based on 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 and waiting for the support roll to complete one full rotation when each step pressure value n is increased. m / n = x, where x is a positive integer greater than 1; After obtaining the roll gap and pressure data under the constant pressure value, a mill stiffness curve is formed to obtain the mill stiffness. The zero-adjustment of the rolling mill equipment includes: Both electric and hydraulic pressing return to the initial position; Bending the roller to a state of balanced force; The electric press stops after reaching the rolling line position; and Hydraulically press down to the contact position with the roll; After the calibration steps are completed, the hydraulic press returns to the rolling mill position, the electric press returns to the initial position, and the main drive stops. 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, which is then used to calculate the mill stiffness. 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 the coefficients of the third-order function of the model, and F is pressure; The subsequent rolling mill model uses a third-order stiffness curve function to calculate the roll gap setting value for each pass of each steel plate.

2. The calibration method for medium and heavy plate rolling mills according to claim 1, characterized in that, During the calibration process, the mill linear speed is 2 m / s.

3. The calibration method for medium and heavy plate rolling mills according to claim 2, characterized in that, In the calibration procedure, n is 200 tons and m is 6000 tons.

4. The calibration method for medium and heavy plate rolling mills according to claim 2, characterized in that, During the calibration process, the time for the support roller to complete one full rotation is 4 seconds.

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