KR20040004946A - Method for controlling the automatic gauge control device and bender of rolling mill in hot rolling process - Google Patents

Abstract

PURPOSE: A method for controlling automatic gauge controller and bender of rolling mill used in hot rolling process is provided to improve shape defects and threadability defects of material to be rolled according to change of bending amount of rolling rolls generated according to change of rolling conditions during roll gap controlling. CONSTITUTION: The method comprises first step of detecting thickness deviation values of the material to be rolled at the exit side of the rolling mill; second step of calculating a roll gap adjusting value using the detected thickness deviation values; third step of calculating crown influence degree of the material to be rolled using the roll gap adjusting value calculated in the second step; fourth step of calculating a bender adjusting value using the calculated crown influence degree; and fifth step of controlling pressure of the automatic gauge controller and bender by outputting the calculated roll gap adjusting value and the bender adjusting value.

Description

Method for controlling the automatic gauge control device and bender of rolling mill in hot rolling process

The present invention is a material according to the change in the bending amount of the rolling roll (rolling) generated in accordance with the change of the rolling conditions in the process of controlling the roll gap between the pair of rolling rolls close up and down to adjust the thickness of the material passing through the rolling roll The present invention relates to an automatic gauge control device of a rolling mill used in a hot rolling process and a control method of a bender for improving shape defects and poor sheetability.

The finishing rolling facility used in the hot rolling process is composed of a continuous tandem rolling mill that uses a plurality of rolling mills 10 arranged in series. By arranging the rolling mills 10 continuously, the rolling efficiency of the material is increased and the product discharged through the rolling mill becomes the final product, thereby increasing the production efficiency.

1 is a schematic installation state diagram of a tandem rolling mill in which a plurality of rolling mills 10 are continuously arranged as described above.

As shown, a plurality of rolling mills 10 are continuously installed adjacent to each other with a suitable distance, automatic gauge control device 106 to control the thickness and shape of the material rolled in each rolling mill 10 And a vendor control device 103 is provided. The rolling mill 10 is also provided with a rolling roll 101, a bender 102, a load measuring device 105, and a thickness detector (not shown), the detailed structure of the rolling mill 10 will be described below. do.

The material passing through each rolling mill 10 has a predetermined thickness and shape set in each rolling mill 10 according to control signals provided by the automatic gauge control device 106 and the vendor control device 103. Rolled to have. The automatic gauge control device 106 and the vendor control device 103 are installed one by one to control a plurality of rolling mills 10 at the same time.

2 is a cross-sectional view showing the configuration of the thickness control and shape control equipment of the conventional rolling mill 10, and shows a structure of one rolling mill for convenience of description.

As shown, in the rolling mill 10, a rolling device for adjusting the interval between the upper and lower pair of rolling rolls 101 for performing thickness rolling of the raw material, and the pair of rolling rolls 101 through which the raw material passes. An automatic gauge control device 106 which collects a thickness deviation of the material passing through the rolling mill exit side and outputs a signal for controlling the interval between the rolling rolls 101 to the pressing device 104; Bender 102 for controlling the bending strain of the rolling roll 101, a bender control device 103 for controlling the bender 102 to compensate for the bending strain, and a rolling load applied to the material to detect the load. Device 105.

The reason for the thickness and shape control by installing the automatic gauge control device 101 and the bender 102 as described above is as follows.

In the hot rolling process, the finishing mill controls the roll gap and rolling speed of each rolling mill to ensure the dimensions (thickness, width, shape, etc.) and surface quality of the target end product. At this time, the roll gap and the speed control of the rolling mill to ensure the target dimension and surface quality of the final product are controlled by various rolling conditions such as the temperature of the material and the composition of the components (carbon, manganese, silicon, titanium, etc.). Variations make it difficult to work with the same roll gap and the same rolling speed in the same steel grade and size. In addition, since the rolling conditions change according to the rolling time in the same rolling material, the rolling roll gap and the rolling speed are variously changed.

In the conventional rolling mill 10, there is a problem that bending occurs in the process of adjusting the roll gap of the rolling mill to obtain a target thickness at the exit of each rolling mill. In other words, in the course of performing the material rolling, as shown in FIG. 3a, the width of the plate 30 is smaller than the width of the rolling roll 20 located above and below, and the rolling roll 20 itself is not a complete rigid body, thereby adjusting the roll gap. Bending deformation of the material 30 occurs due to the force (F) for the purpose, according to the crown (crown) is a thickness deviation of the thickness of the center portion of the material 30 in the width direction is thick and both ends are thinner as shown in Figure 3b (Thickness 1 ≠ thickness 2) is generated.

In addition, due to the change in the roll gap distribution in the width direction due to the bending deformation of the rolling roll 20, the mass flow rate of the material 30 passing per hour in the width direction is changed, and the thickness in the width direction of the center portion of the material 30 is greater than both ends. When too thick, both ends of the material 30 are extended in the longitudinal direction, so that edge waves are formed at both ends as shown in FIG. 4A. As shown in FIG. 4B, the stretching amount in the center portion is increased to obtain a medium wave shaped plate. It is the same as the rolling roll 101 of FIG. 2 of the said rolling roll 20. FIG.

In order to prevent the occurrence of the crown, by using a method of controlling the roll gap in the width direction by increasing the radius of the center portion in the width direction of the rolling roll 20, or the vendor (102) installed in each rolling mill (10) It provides a compensating force for the bending deformation of the work roll to control the generation of the crown and is applied to the rolling mill 10 shown in FIG.

5 is a cross-sectional view showing a correction state of the roll gap change of the rolling roll 20 by controlling the pressure of the bender 102. When the roll gap of both ends of the rolling roll is excessively reduced, the pressure of the bender is increased to roll gap displacement at the end. On the contrary, if the center roll gap becomes too small, the bender pressure is lowered to control the roll gap in the width direction to stabilize the width direction of the material 30 so that medium wave and onion do not occur in the target crown shape and material. Control the vendor 102 to be a flat material.

6 shows the control operation state of the automatic gauge control device 106 and the vendor 102 as described above.

The automatic gauge control device 106 collects the thickness deviation using a thickness detector (not shown) located at the rear of the rolling mill 10, and calculates and outputs a roll gap variation of the rolling roll 101. According to the output signal of the roll gap change amount, the rolling device 104 changes the roll gap between the rolling rolls 101, and accordingly, the thickness of the rolled material is adjusted. The thickness deviation amount of the material is continuously collected by the thickness detector and input to the automatic gauge control device 106 to adjust the thickness of the material.

On the other hand, the operating state of the vendor 102 is as follows. By the load detection device 104 which detects the rolling load of the raw material, the variation in the rolling load is measured in real time, and thus the roll gap distribution in the width direction is calculated. When the roll gap distribution is calculated, the crown of the material is predicted based on this. Using the crown prediction value Tc of the material, the bender pressure for forming the target crown is calculated and the deviation is controlled. The automatic gauge control device 106 and the vendor equipment 102 are conventionally controlled in separate states without being associated with each other. The control of the material crown is controlled using the following equations. Equation 1 below is a formula for calculating the conventional material crown prediction value (Tc).

Equation 1 is as follows.

Where k = lateral stiffness factor ｆ (R _f ): rolling load influence function

E _f : Vendor Effect Factor 4 f (R _bk ): Vendor Power (Current) Performance

η: pan crown dielectric constant f (Cs): pan crown dielectric constant

The bender correction amount F _bs necessary for achieving the material (plate) crown target value is equal to that of Equation 2 when the bender pressure amount necessary for achieving the target is calculated inversely from Equation 1.

Equation 2 is as follows.

In addition, the vendor correction amount Fbs can be obtained from F _bs = target vendor pressure-vendor power (current) performance value F _bk .

In the method of predicting and controlling the material crown by measuring the rolling load by using the automatic gauge control device 106 and the vendor control device 103 as described above, the following problems occur.

The thickness gap detected by the thickness detector (not shown) located on the exit side of the finishing mill is read, and the roll gap displacement output from the automatic gauge control device 106 is transmitted to the material 30 to perform thickness rolling, and the roll gap displacement. Due to this, the load applied to the material 30 is changed, measured by the load detection device 105 to estimate the width of the roll gap distribution and the crown degree of the material, and to control the pressure by the bender 102 for the crown control. In the process of adjustment, the variation of rolling load detection value is generated by friction loss between equipment components, and it is controlled by response time delay, calculation error, etc. by using indirect method of detecting rolling load and predicting bending deformation of rolling roll. The problem that the degree of deterioration occurs.

Moreover, there is no mutual information exchange between the automatic gauge control device 106 which is a thickness control facility and the vendor control device 103 which is a shape control facility, so that the roll gap control function of the automatic gauge control device 106 and the control of the vendor 102 are controlled. When the roll gap is pushed by the automatic gauge control device 106 to control the thickness deviation due to the collision of functions, this causes a change in the bending amount of the rolling roll, thereby causing a deterioration of the shape of the material due to the roll gap distribution unevenness in the width direction. .

In addition, when the shape of the material decreases, the control amount of the bender pressure increases, and as the force acts in the direction of lifting the roll gap at both ends, the thickness control device of the automatic gauge control device 106 and the bender 102 cause the thickness deviation of the material again. The shape control equipment caused mutual interference and the vicious cycle was repeated without control problems being solved.

The present invention is to solve the above problems, an object of the present invention is to predict the shape change amount of the material using the control information of the rolling mill roll gap output from the automatic gauge control device used for controlling the thickness of the material in the rolling mill, bender The present invention provides an automatic gauge control device of a rolling mill and a vendor's control method used in a hot rolling process that can stabilize the shape of a material early by controlling the pressure.

Another object of the present invention is the automatic gauge control device of the rolling mill used in the hot rolling process that can achieve the stabilization and thickness of the material shape by minimizing the interference phenomenon between the thickness control function and the shape control function applied to the rolling mill and To provide a vendor control method.

Another object of the present invention is to reduce the defective rate of the final product produced in the hot rolling process to improve the quality, and to control the automatic gauge control device and bender control method of the rolling mill used in the hot rolling process to improve the customer satisfaction To provide.

1 is a state diagram of the continuous rolling mill used in the conventional hot rolling process,

2 is a cross-sectional view showing the configuration of a rolling mill conventionally used;

3A is a cross-sectional view showing a bending deformation state of a rolling roll, FIG. 3B is a partial perspective view showing occurrence of thickness deviation of a raw material due to deformation of the rolling roll;

4A and 4B are perspective views illustrating a shape change of a material according to a roll gap distribution change;

5 is a cross-sectional view showing a roll gap change state of a rolling roll by bender control;

6 is a flowchart showing a control state of a conventional automatic gauge control apparatus and a vendor;

7 is a flowchart illustrating a control method according to the present invention;

8 is a schematic view showing the bending amount of the roll calculated by the present invention;

9a and 9b are graphs showing the shape change of the material according to the conventional and the method of the present invention, respectively.

※ Explanation of symbols about main part of drawing ※

10: rolling mill 20: rolling roll

30: material 101: rolling roll

102: vendor 103: vendor control device

104: reduction device 105: load detection device

106: Automatic Gauge Control (AGC) device

The automatic gauge control device of the rolling mill and the bender control method used in the hot rolling process of the present invention for achieving the above object, the automatic gauge control device and rolling roll bending of the rolling mill used to control the thickness of the material in the hot rolling process A method for controlling a vendor for controlling a change amount, the method comprising: a first step of detecting a thickness deviation amount of a material at an exit side of a rolling mill; a second step of calculating a roll gap correction amount using the thickness deviation amount; A third step of calculating a crown influence degree of the material by using the roll gap correction amount calculated in the second step; A fourth step of calculating a vendor correction amount using the crown influence; And outputting the roll gap correction amount and the vendor correction amount to control pressure of the automatic gauge control device and the vendor.

Hereinafter, with reference to the accompanying drawings will be described in detail the automatic gauge control device and the control method of the vendor of the rolling mill used in the hot rolling process of the present invention.

7 is a flowchart showing an automatic gauge control device of a rolling mill and a vendor control method used in a hot rolling process according to the present invention.

As shown, the first step detects the thickness deviation with respect to the raw material on the exit side of the finishing mill 10. The detection of the thickness deviation amount is performed as in the prior art by a thickness detector (not shown) provided on the exit side of the rolling mill. The detected thickness deviation amount is input to the automatic gauge control device 106 as before.

As a second step, the automatic gauge control device 106 (AGC) calculates the roll gap correction amount of the rolling mill using the thickness deviation amount input from the thickness detector. The roll gap correction amount is also calculated by the same method as in the prior art.

After the roll gap correction amount is calculated by the automatic gauge control device 106 as described above, instead of outputting a control signal to the pressing device 104 to change the roll gap of the rolling mill as in the prior art, the crown effect of the material as a third step Calculate the degree. The crown influence of the material is estimated by calculating the widthwise bending strain of the rolling roll by the roll gap correction amount and calculating the degree of crown change of the material thereby. Said material crown prediction value Tc is computed by Formula (3) and (4) described below. Using the calculated material crown prediction value Tc, the vendor (pressure) correction amount is calculated and transmitted to the vendor 102 as a fourth step, and the vendor 102 uses the control information to control the pressure of the vendor 102. Add or subtract. Further, the roll gap correction amount is output to the reduction device 104 to adjust the roll gap. Equation 3 is as follows.

Where k = lateral stiffness factor ｆ (R _f ): rolling load influence function

E _f : Vendor Effect Factor 4 f (R _bk ): Vendor Power (Current) Performance

η: pan crown dielectric constant f (Cs): pan crown dielectric constant

S _K : Roll gap influence coefficient f (Sf): Roll gap variation

Indicates. In addition, the vendor target for achieving the target crown is

By Equation 4

Becomes Accordingly, the vendor correction amount Fbs can be obtained from the vendor correction amount F _bs = vendor target value-vendor power (current) performance value F _bk .

In the above Equation 3, the roll gap influence coefficient S _k was calculated using the following Equation 5 from the widthwise bending displacement of the rolling roll as shown in FIG. 8. It can be seen that the roll gap distribution in the width direction changes according to the bending of the rolling roll. Equation 5 is as follows.

The determination of a and b can be obtained by a least square method that minimizes the square of each error. This is shown in the following determinant.

In addition, in the control method of the present invention, after the calculation of the bender (pressure) correction amount in order to minimize the control vicious cycle caused by the output of the automatic gauge control device 101 and the bender 102, the influence of the thickness deviation due to the change in the bender pressure In order to minimize the error, the thickness deviation of the rolling mill exit by the vendor modification is predicted, the predicted thickness deviation is compared with the deviation limit (standard value), and the thickness deviation of the finishing exit is detected again according to the comparison result. The roll gap correction amount is calculated or the roll gap correction amount and the vendor correction amount are determined and output.

In other words, if the thickness deviation on the exit side is less than the deviation limit (reference value), the roll gap correction amount and the vendor correction amount already set in the third and fourth steps are output to control the automatic gauge control device and the vendor, respectively. If the thickness deviation is larger than the deviation limit, the roll gap is changed by the thickness deviation, and the material shape change and vendor correction amount due to the roll gap change are calculated to compensate for the vendor pressure. By repeating these trial-errors, the optimum roll gap and vendor correction can be calculated, and non-interference control is applied between the automatic gauge control system and the vendor to reduce the thickness deviation and stabilize the shape of the material. Can be achieved simultaneously.

The flatness change of the material by the conventional control method and the control method according to the present invention is shown in Figs. 9A and 9B, respectively.

As shown, the flatness index indicating the height of the material H relative to the unit pitch (P) indicating the degree of shape change of the material by the present invention rather than the flatness by the conventional method, the head of the material, And a significant improvement over the middle, tail.

According to the present invention as described above by using the control information of the rolling roll gap output from the automatic gauge control device used to control the thickness of the material in the rolling mill to predict the shape change amount of the material, and control the bender pressure to control the shape of the material early It can stabilize, minimize the interference between the thickness control function and the shape control function applied to the rolling mill to achieve the stabilization and thickness stabilization of the shape of the material, and also reduce the defective rate of the final product produced in the hot rolling process. By improving the quality, the customer's satisfaction is effective.

Claims (4)

In the method of controlling the automatic gauge control device of the rolling mill used to control the thickness of the material in the hot rolling process and the bender controlling the amount of bending change of the rolling roll, A first step of detecting the thickness deviation of the raw material at the exit side of the rolling mill; Calculating a roll gap correction amount using the thickness deviation amount; A third step of calculating a crown influence degree of the material by using the roll gap correction amount calculated in the second step; A fourth step of calculating a vendor correction amount using the crown influence; And a fifth step of controlling the pressure of the automatic gauge control device and the bender by outputting the roll gap correction amount and the vendor correction amount, and the method of controlling the automatic gauge control device and the vendor of the rolling mill used in the hot rolling process. . The method of claim 1, In order to minimize the influence of the thickness deviation due to the change in the vendor pressure after the calculation of the vendor correction amount in the fourth step, the control method may minimize the control vicious cycle caused by the automatic gauge control device and the output of the vendor. When the thickness deviation of the exit side of the rolling mill is predicted by the vendor pressure correction, and the predicted thickness deviation is compared with the deviation limit, and the thickness deviation amount of the exit side is smaller than the deviation limit, the number of roll gaps already set in the third and fourth steps is Output the quantity and vendor correction amount, and if the thickness deviation is larger than the deviation limit, change the roll gap by the thickness deviation, and then calculate the material shape change and vendor correction amount due to the roll gap change to compensate the vendor pressure. An automatic gauge control device of a rolling mill used in a hot rolling process and a vendor's control method further comprising a. The method according to claim 1 or 2, In the third step, the calculation of the crown influence of the material is achieved by calculating the material crown prediction value Tc, calculating the vendor pressure target value, and calculating the vendor correction amount Fbs, The material crown predicted value (Tc) Where k = lateral stiffness factor ｆ (R _f ): rolling load influence function E _f : Vendor Effect Factor 4 f (R _bk ): Vendor Power (Current) Performance η: pan crown dielectric constant f (Cs): pan crown dielectric constant S _K : Roll gap influence coefficient f (Sf): Roll gap variation Calculated by the, the bender pressure target value, The vendor correction quantity (Fbs) is calculated by "bender correction quantity (F _bs ) = vendor target value-vendor force (current) performance value (F _bk )" used in the hot rolling process, characterized in that Automatic gauge control device of rolling mill and bender control method. The method of claim 2, The roll gap influence coefficient (Sk) is the following formula Obtained by the above, a, b is The automatic gauge control device of the rolling mill used in the hot rolling process and the vendor's control method, characterized in that obtained by.