KR100832969B1 - Method for estimating and preventing width deviation of strip in strip roll process - Google Patents

Abstract

The present invention relates to a method for predicting and preventing a width deviation of a thick steel plate having a longitudinal thickness difference at the time of steel sheet rolling, and the present invention is a method for predicting and preventing a width deviation of a thick steel sheet having a longitudinal thickness difference at the time of steel sheet rolling In the case of replacing the rolling rolls, the rolling rolls are contacted without rolling materials, the hydraulic pressure is applied to the lower cylinder of the rolling rolls, and then the rolling load (F) and the hydraulic cylinder position (SO) are measured, and the rolling mill stiffness coefficient is used. First steps (S110 and S120) of calculating (M = F / SO); In the case of the blasting path, before each pass rolling, including the calculated stiffness coefficient (M), the thickness and thickness difference calculated from the pass schedule main program (VOB), the thickness and thickness difference, the rolling load and the rolling load deviation, And second step (S130), S140 for predicting and calculating the amount of the width deviation using the total length of the material prior to the rolling and the material length of the scarfing unit; A third step (S150) of performing rolling by applying the predicted width deviation amount; If it is not the last pass by determining whether it is the last pass, after the completion of rolling for each pass, the left and right load deviation results are calculated using the left and right rolling load deviations, the right and left roll gap difference, and the rolling mill left and right stiffness difference, and the left and right width deviations. After calculating the generation amount performance, the roll gap correction value performance of the scarfing portion is calculated, and proceeds to the second step, and in the case of the last pass, the fourth step (S160, S170) is provided.

Thick steel plate, rolling, width deviation occurrence, prediction, prevention

Description

METHODS FOR ESTIMATING AND PREVENTING WIDTH DEVIATION OF STRIP IN STRIP ROLL PROCESS}

1 is a schematic diagram of a general thick steel plate mill rolling line.

2 is a block diagram of an existing meander control system.

3 is a block diagram of a roll gap control system.

4 is a layout diagram of a load detection device, a roll arrangement, and a hydraulic device to obtain rolling mill left and right rigidity.

5 is a calculation example of the rolling mill stiffness.

6 is an explanatory diagram of a conventional method for rolling a thick steel sheet having a thickness difference between right and left.

7 is an explanatory diagram of a method for rolling bread of a thick steel sheet having left and right thickness differences of the present invention.

8 is an explanatory diagram of a rolling method of the first RS (Rolling Schematic).

Fig. 9 is a comparison of the shape of materials before and after the conventional bake rolling.

10 is an overall flowchart of a method for controlling width rolling of a thick steel sheet having a longitudinal thickness difference.

FIG. 11 is a flowchart showing the stiffness calculation process (WDMC) of FIG. 10.                 

FIG. 12 is a flowchart illustrating a process of predicting left and right width deviation generation amount PRERE of FIG. 10.

FIG. 13 is a flowchart illustrating a process of measuring a left and right width deviation generation amount POSTWID of FIG. 10.

14 is an explanatory diagram for distinguishing the front, rear and left and right sides of the rolling mill.

15 is an explanatory diagram of a pass.

16 is an explanatory diagram of a sequence.

Explanation of symbols on the main parts of the drawings

2: rolling load detection device 3: roll gap adjusting device

4: Back Up Roll 5: Work Roll

6: Roll Chock 7: Hydraulic Cylinder

8: Mill housing 9: Mill stiffness coefficient (Mill Constant)

10: Drive Side 11: Work Side

12: Entry Side 13: Rolling Side

WDMC: Stiffness Factor Calculation Program

PREWID: Left and right width deviation prediction calculation program

POSTWID: left and right width deviation performance calculation program

The present invention relates to a method for predicting and preventing a width deviation of a thick steel plate having a longitudinal thickness difference at the time of steel sheet graining, in particular, the width deviation amount that can be generated for each pass from the initial rolling pass of the breading sequence to the final rolling completion pass, Predicted by using the stiffness coefficient (M), thickness and thickness difference of the top and the scarfing part, rolling load and rolling load variation, the total length of material before rolling and the material length of the scarfing part, and the width by the thickness difference in the longitudinal direction Width deviation is controlled to prevent the width deviation before the deviation occurs, and thus, when each pass is completed, the width deviation prediction of the thick steel sheet having the longitudinal thickness difference at the time of rolling the steel plate to correct the predicted width deviation and It relates to a prevention method.

In general, Figure 1 is a schematic diagram of a general thick steel sheet mill rolling line, referring to Figure 1, the general thick steel sheet mill rolling line is composed of a heating furnace, rolling mill, hot calibrator and cooling zone. Such thick steel rolling is carried out by determining the rolling method according to the shape, width ratio, and steel type of the material. In consideration of the efficiency of the rolling work, it is generally performed by RS1 (rolling method 1: Rolling Schematic1). When partial scarfing is performed in the width direction of the material due to defects on the surface of the material, a width deviation after the width-of-rolling rolling is usually generated depending on the degree of scarring, causing a shortage of width. SCARFING is to melt in the thickness direction to remove defects on the surface of the material in the line process.

2 is a block diagram of an existing meandering control system, and FIG. 3 is a block diagram of a roll gap control system, wherein the left and right rolling load deviations and left and right roll gaps (RG: rolling mills) measured in FIG. 2 are based on the measured meandering amount. The gap between the up and down work rolls and the rolling left and right stiffness difference were used to calculate the left and right roll gap difference that can minimize the meandering amount in the process computer of FIG. As shown in Fig. 3, the roll gap control device performs feedback control by using an error between the longitudinal target amount of the thick plate and the measured amount.

4 is a layout diagram of a load detection device, a roll arrangement, and a hydraulic device to obtain rolling mill left and right rigidity. 5 is a calculation example of rolling mill rigidity. 6 is an explanatory diagram of a conventional method for rolling a thick steel sheet having a thickness difference between right and left.

Referring to Figure 6, the thick steel plate having a thickness difference is rotated by 90 ° to perform the breading roll in the breading roll mill, after performing the breading roll shows the shape of the thick steel sheet.

8 is an explanatory view of a rolling method of the first RS (Rolling Schematic), a general general thick steel rolling process is carried out evenly rolling, breading, length rolling, in reference to Figure 9, the conventional method According to this, there is a large deviation in the width of the thick steel plate after the breading.

As such, since there is no automatic width shape control rolling method of the thick steel sheet having a partial left and right thickness difference, in the related art, the conventional method is to perform the breader rolling operation so as not to cause the shortage of width through manual control of the operator. There were the following problems.

First, the operator performed manual deburring rolling on the basis of the scarfing part to prevent shortage deficiency, but because of deburring rolling based on the operator's experience and prediction, The width of the scarfing part also shows a lot of deviation from the target width. Secondly, because the breader is rolled on the basis of the scarfing part, the part that is not scarfed is excessively exposed. Thereafter, there was a problem such as causing the final material length shortage after the length-rolling rolling process and subsequent post-processing delay.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and therefore, an object of the present invention is to determine the width deviation amount that can be generated for each pass from the initial rolling pass of the bake sequence to the last rolling completion pass. Prediction is made using the thickness and thickness difference of the scarfing part, the rolling load and the rolling load variation, the overall length of the material before the rolling and the material length of the scarfing part, and the width deviation before the width deviation due to the thickness difference in the longitudinal direction occurs. It is to control the prevention, and accordingly to the width deviation prediction and prevention method of the thick steel plate having a longitudinal thickness difference at the time of steel plate rolling to correct the prediction width deviation by collecting the rolling performance value at the completion of each pass.

As a technical means for achieving the above object of the present invention, the method of the present invention in the method of predicting and preventing the width deviation of the thick steel sheet having a longitudinal thickness difference at the time of steel sheet rolling, when the rolling roll is replaced, A first step of contacting the rolling rolls without a rolling material, applying a hydraulic pressure to the rolling cylinder lower cylinder, measuring a rolling load and a hydraulic cylinder position, and calculating a rolling mill stiffness coefficient using the rolling roll; In the case of the blasting pass, before each pass rolling, the width deviation occurrence prediction is calculated by using the calculated rolling load of the top part and the rolling load of the scarfing part calculated in the pass schedule main program, including the stiffness coefficient calculated above. Second step; A third step of rolling by applying the predicted width deviation amount; If it is not the last pass by determining whether it is the last pass, after completion of rolling for each pass, the left and right load deviations are calculated using the calculated rolling mill left and right stiffness difference, performance left and right rolling load deviation and performance left and right roll gap difference, and right and left width deviation After calculating the generation amount performance, the roll gap correction value performance of the scarfing portion is calculated, and proceeds to the second step, and in the case of the last pass, characterized in that it comprises a fourth step of ending.

Hereinafter, with reference to the accompanying drawings, the configuration and operation will be described in detail with respect to the width deviation prediction and prevention method of the thick steel plate having a longitudinal thickness difference at the time of the thick steel plate according to the present invention.

The present invention predicts the amount of width deviation that can occur for each pass from the initial rolling pass of the length measuring sequence to the last rolling completion pass, and controls to prevent the occurrence of the width deviation before the width deviation due to the thickness difference in the longitudinal direction occurs. When each pass is completed, the rolling performance value is collected and the estimated width deviation is corrected so that the steel sheet can be manufactured by performing stable rolling without generating the width deviation, and thus the length of the thick steel sheet when the rolling rate can be improved. The present invention relates to a method for predicting and preventing a width deviation of a thick steel plate having a direction thickness difference. An overall flowchart of the process is illustrated in FIG. 10 and described in detail with reference to FIG. 10.

Referring to FIG. 10, a width deviation prediction and prevention method of a thick steel sheet having a longitudinal thickness difference at the time of steel plate rolling according to the present invention may include a first step (S110 and S120) of obtaining a stiffness value and a second width prediction amount. Steps (S130, S140), the third step (S150) to perform rolling, after calculating the width deviation results for each pass before it is determined to repeat or end, iteratively repeats the third step from the second step described above It consists of a fourth step (S260, S170) to be carried out, each of these steps is made in the control unit to control the rolling by receiving the detected difference difference, the load difference and the cylinder position difference, it will be described as follows.

First, in the first step (S110, S120), when the rolling rolls are replaced, the rolling rolls are contacted without the rolling material, the hydraulic pressure is applied to the lower cylinder of the rolling rolls, and then the rolling load (F) and the hydraulic cylinder position (SO) are measured. Using this, calculate the rolling mill stiffness coefficient (M = F / SO).

In detail, with reference to FIG. 11, immediately after rolling roll replacement, a rolling mill left and right rigidity difference is calculated, which is used in the following second and fourth steps. Immediately after the rolling roll replacement, as shown in FIG. 4, the rolling rolls are in contact with each other (called a kiss roll) (S121), and hydraulic pressure is applied to the lower hydraulic cylinder of the rolling mill (S122). At this time, the left and right rolling load difference, the right and left hydraulic cylinder position difference is calculated using the following equation (1) (S123). If there is no rolling roll replacement applies the previous left and right stiffness (S124).

Where S0 is the hydraulic cylinder position (mm), h1 is the exit thickness (mm), F is the rolling load (Ton), M is the stiffness coefficient (Ton / mm) of the rolling mill, a is the plasticity coefficient of the rolled material (Ton / mm) )to be.

In Equation 1 above, when the rolling rolls are brought into contact with each other without the rolling material immediately after the rolling roll replacement, the rolling material exit thickness h1 and the rolling material plasticity coefficient α become "0". M) can be obtained by the following equation.

When calculating the left and right stiffness of the rolling mill as described above, except for the section in which the rolling load and the hydraulic cylinder position are curved as shown in FIG. 5, the slopes are obtained by selecting the straight sections and using the least-square method, respectively. Becomes

Next, in the second step (S130, S140), in the case of the breading pass, the top portion and the scarfing portion calculated in the pass schedule main program (VOB), including the calculated stiffness coefficient (M) before each pass rolling. The thickness and thickness difference, the rolling load and the rolling load variation, and the overall length before the even rolling and the material length of the scarfing part are predicted to calculate the amount of width deviation, which will be described in detail with reference to FIG. 12.

Referring to FIG. 12, in the first process of the second step S140, the rolling load deviation amount ΔPi of the i pass is obtained, and the rolling load of the top portion of the i pass is calculated in the pass schedule model VOB of the rolling model. Based on the rolling load Pi of the top part, the rolling load of the Scarfing part is obtained and the calculated rolling load is predicted using this.

First, the weight under rolling between the Scarfing part and the top part is predicted and calculated, which is calculated by the following equation.

Where ΔH is the thickness difference between the scarfing part and the top part, Hi is the thickness of the top part (normal part> Scarfing part), R is the hot deformation resistance, Wi is the side width, and α is the roll. Influence factor (1.0 to 1.3).

Using the above equation (3), the rolling load deviation amount ΔPi of the i pass is obtained by the following equation (4). Here, it is assumed that the number of selection passes (the number of i passes) is two passes.

At this time, the rolling load of the top portion of the i pass is calculated from the pass schedule model (VOB) of the rolling model, and the rolling load of the scarfing portion is based on the rolling load Pi of the top portion. Obtained by 5.

Next, in the second process of the second step (S140), the rolling length Li of the top portion after the i pass is obtained. In this case, it is assumed that the amount of change in the width before and after the i pass is insignificant and thus equal. It is expressed by the following equation by applying the law of volume, and using this, the rolling length Li of the top portion is obtained by the following equation.

Where L is the total length of the material before rolling, a is the material length of the scarfing part, ΔH is the thickness difference between the top part and the scarfing part, and Hi is the exit thickness of the top part.

In addition, the rolling length ai of the Scarping part after i pass is calculated | required by following formula (8), respectively. In this case, the width before and after the selection i pass is assumed to be the same since the change amount is insignificant as in the normal part. Therefore, if the equation is applied by applying a constant volume law, it is expressed as Equation 8 below. ) Is obtained by the following equation (9).

Using the rolling lengths according to Equation 7 and Equation 9, rolling is performed by applying different rolling loads to the top part and the scarfing part to obtain a material having a uniform thickness after the final pass of the even rolling process.

In the second process of the second step S140, the roll gap correction value ΔSi of the scarfing portion is predicted, and the calculation of the roll gap correction value ΔSi of the scarfing portion is performed on the top portion and the swap portion. It is calculated as in Equation 10 using Equation 1 to obtain the difference between the rolling load ΔPi of the capping portion and the left and right stiffness difference of the rolling mill.

Here, ΔS I is the roll gap correction value (i pass) of the scarfing part, ΔPi is the rolling load deviation (i pass) of the top part and the scarfing part, Hi is the exit thickness (i pass) of the top part, and Pi is the rolling load of the top part. (i-pass).

For reference, FIG. 14 is an explanatory view for distinguishing the front, rear, and left and right sides of the rolling mill. Referring to FIG. 14, the driver side is merely used to distinguish the left and right sides of the rolling mill as shown in FIG. 14. It refers to the side 10 in which the motor which drives a rolling roll is located by name. The work side refers to the opposite side 11 of the side 10 on which the motor which drives the rolling roll is located, as shown in FIG. 14, simply to distinguish the left and right sides of the rolling mill. The front side of the rolling mill is a roller table 12 on the side with a heating furnace on the basis of the rolling mill of FIG. 14, and the rear side of the mill is a roller table 13 on the side of the rolling mill on the basis of the rolling mill of FIG. 14. In addition, a pass is a pass from the # 1 state before the rolling material of FIGS. 14 and 15 to # 3 which is the rolling completion through the # 2 state which is rolling, and is called one pass. In addition, referring to Figures 15 and 16, the sequence (Sequence) is a thick steel sheet rolling is composed of each step of # 1 even rolling, # 2 width rolling, # 3 length rolling, the rotation of the rolled material ( Each rolling step divided by Turning is called a sequence. As shown in Fig. 16, the rolling fixation of a thick steel plate is divided into a rolling even sequence, a breading sequence and a lengthening sequence, and the present invention relates to the breading sequence of a thick plate steel having a longitudinal thickness difference.

Then, in the third step, rolling is applied by applying the predicted width deviation generating amount, which is applied to the rolling control amount, that is, the estimated width deviation generating amount is applied to the control signal of the hydraulic cylinder of the rolling roll. Since the actual rolling control process is the same as the conventional process, more detailed description is omitted.

Finally, referring to FIGS. 10 and 13, in the fourth step (160, 170), it is determined whether the last pass (LP: last pass) in the breading sequence, and if not the last pass, after the completion of rolling for each pass, the calculation After calculating the results of left and right load deviations using the right and left stiffness difference, right and left rolling load deviation, and right and left roll gap difference (S172), and calculating the left and right width deviation generation performance (S173), the roll gap correction value of the scarfing part is calculated. The result is calculated (S174), and then proceeds to the second step, if the last pass ends.

Referring to Figure 7, according to the method of the present invention by rotating the thick steel plate having a thickness difference by 90 ° to perform the depoking rolling in the deburring rolling machine, after performing the depoking rolling according to the present invention the shape of the thick steel sheet Is showing.

According to the present invention as described above, the width deviation difference that can occur for each pass from the initial rolling pass of the breading sequence to the last rolling completion pass, the rigidity coefficient (M), the thickness and thickness difference of the top and the scarfing part, the rolling load and rolling Predicts the load deviation and the overall material length before even rolling and the material length of the scarfing part, and controls to prevent the width deviation before the width deviation due to the thickness difference in the longitudinal direction occurs. By collecting the rolling performance value to correct the predicted width deviation, it is possible to produce a steel sheet by performing a stable rolling without generating excessive width deviation, thereby having a special effect to improve the error rate.

That is, in order to control the width shape of thick steel plates having partial thickness differences in the width direction, the gap between the initial rolling pass and the last completed pass of the width cutting sequence is predicted to generate the width deviation so that the gap does not occur. By correcting the width difference generation amount is controlled, it is effective to produce a thick steel sheet having a good width shape that does not cause shortage of material width.

The above description is only a description of specific embodiments of the present invention, and the present invention is not limited to these specific embodiments, and various changes and modifications of the configuration are possible from the above-described specific embodiments of the present invention. It will be apparent to those skilled in the art to which the present invention pertains.

Claims (2)

In the width deviation prediction and prevention method of a thick steel sheet having a longitudinal thickness difference at the time of thick steel sheet When the rolling rolls were replaced, the rolling rolls were contacted without rolling materials, the hydraulic pressure was applied to the lower cylinder of the rolling rolls, and then the rolling load (F) and the hydraulic cylinder position (SO) were measured, and the rolling mill stiffness coefficient (M = F / SO) and the first step (S110, S120) for calculating the stiffness difference between the rolling mill; In the case of the blasting path, before each pass rolling, including the calculated stiffness coefficient (M), the thickness and thickness difference calculated from the pass schedule main program (VOB), the thickness and thickness difference, the rolling load and the rolling load deviation, A second step (S130, S140) of predicting and calculating a width deviation generation amount using the entire length of the material before the rolling and the material length of the scarfing unit; A third step (S150) of performing rolling by applying the predicted width deviation amount; And If it is not the last pass by determining whether it is the last pass, after the completion of rolling for each pass, the left and right load deviation results are calculated using the left and right rolling load deviations, the right and left roll gap difference, and the rolling mill left and right stiffness difference, and the left and right width deviations. After calculating the generation amount performance, after calculating the roll gap correction value performance of the scarfing part proceeds to the second step, and in the case of the last pass, the thick steel plate characterized in that it comprises a fourth step (S160, S170) A method for predicting and preventing the width deviation of thick steel sheets having a longitudinal thickness difference at the time of graining. The method of claim 1, wherein the second step (S140) The rolling load deviation amount ΔPi of the i pass is obtained, and the rolling load of the top portion of the i pass is calculated from the pass schedule model (VOB) of the rolling model, and the scarping is performed based on the rolling load Pi of the top portion. Obtaining a rolling load of the Scarfing part and using the same to predict and calculate the rolling load; a second step of obtaining the rolling length ai of the scarfing part and the rolling length Li of the top part after the i pass respectively; And And a third process of predicting the roll gap correction value (ΔSi) of the scarping portion. The method of predicting and preventing the width deviation of a thick steel sheet having a longitudinal thickness difference during thick steel sheet rolling.

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