KR20080058725A - Calculation method of a thickness of a strip and calculation method of roll gap using the same - Google Patents

Abstract

A sheet thickness calculating method and a roll gap error calculating method using the same are provided to control a roll stably and to improve thickness accuracy of the sheet by storing measured speed and thickness in a resister and calculating the thickness of a sheet being rolled, using the stored speed and thickness and output speed of a rolled sheet. A sheet thickness calculating method comprises the steps of: measuring speed and thickness of a sheet before rolling; storing the measured speed and thickness in a resister(10) sequentially; and calculating the thickness of the sheet being rolled from the stored speed and thickness and output speed of a rolled sheet.

Description

Sheet Thickness Calculation Method and Calculation Method of Roll Gap Error Using It {CALCULATION METHOD OF A THICKNESS OF A STRIP AND CALCULATION METHOD OF ROLL GAP USING THE SAME}

1 is a view for explaining a plate thickness calculation method according to an embodiment of the present invention.

2 is a view for explaining the operation of the register according to an embodiment of the present invention.

3 is a view for explaining the operation of the roll shown in FIG.

The present invention relates to a sheet thickness calculation method for the plate thickness control of the rolling mill and a method of calculating the roll gap error using the same.

In the process of producing a metal sheet, such as steel sheet, copper plate or aluminum plate, in order to produce a rolled sheet material having a constant thickness, the rolled sheet material enters the mouth side of the rolling mill and is rolled by a roll to be rolled to a final constant thickness.

Since the rolled sheet material on the side is not constant in thickness, the plate thickness is rolled to a certain size due to various disturbance factors such as the rolling force applied to the roll of the rolling mill due to the change in the thickness of the side, thereby changing the roll spacing between the upper and lower sides. I do not lose.

According to the conventional plate thickness control method, in order to overcome the above problems, the plate thickness is measured by a thickness gauge for measuring the thickness of the plate on the exit side of the rolling mill stand, and then the plate thickness by the target plate thickness and the measured plate thickness. The error of was obtained.

Subsequently, the obtained thickness error is transmitted to the feedback controller, and the control output value is obtained by the control logic for correcting the plate thickness. Subsequently, the plate | board thickness was controlled to drive the hydraulic cylinder which changes the position of a roll up and down to follow the target plate | board thickness.

However, in the conventional plate thickness control method, since the thickness gauge measuring the plate thickness is installed at a certain distance from the roll of the rolling mill, there is a time delay in the plate thickness measurement, and thus the actual thickness of the current rolled sheet being rolled by the roll. And different plate thicknesses were measured to determine the correct plate thickness.

Accordingly, the control of the plate thickness by the plate thickness measured differently from the actual thickness is performed to cause a problem that the precision of the plate thickness falls.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for calculating the thickness of a plate which can grasp a more accurate sheet thickness error than the conventional method.

Another object of the present invention is to provide a sheet thickness calculation method and a roll gap error calculation method using the same, which can stably calculate the inclination angle of the roll to stably control the roll and improve the thickness accuracy of the plate.

The plate thickness calculation method according to an embodiment of the present invention for achieving the above object comprises the steps of measuring the speed and thickness of the side rolled sheet material before rolling; Sequentially storing data relating to the measured speed and thickness in a register; And calculating the thickness of the rolled sheet material in the roll forming state from data on the speed and thickness stored in the register and data on the speed of the exit rolled sheet material after the roll forming by the roll.

According to one or more exemplary embodiments, a method of calculating a roll gap error includes calculating an initial roll tilt angle and a current roll tilt angle from a first roll gap and a second roll gap; Calculating an intervention angle error using an initial set tilt angle set at the beginning of the rolling process and an intermediate set tilt angle according to an input during the rolling process; Calculating a total tilt angle error from the calculated initial roll tilt angle, current roll tilt angle, and intervention angle error; And calculating a roll gap error from the total tilt angle error and the plate thickness error.

According to the plate thickness calculation method according to the present invention, there is an advantage that can grasp the accurate plate thickness error than the conventional method.

In addition, the sheet thickness calculation method according to the present invention and the method of calculating the roll gap error using the same has the advantage that it is possible to quickly calculate the inclination angle of the roll to control the roll stably and improve the thickness precision of the plate.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining a plate thickness calculation method according to an embodiment of the present invention, Figure 2 is a view for explaining the operation of the register according to an embodiment of the present invention.

Referring to Fig. 1, when the rolled sheet material 7a enters the rolling mill stand from right to left, the rolled sheet material thickness H _in is measured by the entry thickness gauge 5, and at the same time, the rolled plate material by the entry plate speedometer 3 Measure the inlet velocity V _in of (7a). The side rolled sheet material thickness H _in measured by the side wall thickness gauge 5 is the thickness in a center part with respect to the width direction of the roll 1.

In addition, the exit plate speedometer 4 measures the exit speed V _OUT of the rolled sheet material 7c that is roll formed by the roll 1. The volume per unit time of the rolled plate members 7a and 7c in the moving state is determined by the product of the thickness, the width of the rolled plate members 7a and 7c, and the moving speed of the rolled plate members 7a and 7c.

Therefore, when the width change of the rolled board members 7a and 7c before and after rolling is negligible, the exit rolled sheet material thickness H _out is determined by the following formula.

H _out = (V _in / V _out ) × H _in

The plate thickness of the current rolled sheet material 7b being rolled on the roll 1 is the value measured in the past by the side thickness gauge 5 installed in front of the constant distance x from the roll 1, and the speed is also in the past. Is already measured.

Therefore, the above-described measured plate thickness and plate speed are stored in the register 10 in order to utilize the plate thickness and plate speed measured in the past.

Referring to FIG. 2, data relating to the plate thickness measured by the side thickness gauge 5 and the plate speed measured by the plate speedometer 3 are sequentially stored in the register 10.

The operation method of the register 10 for storing the data is not particularly limited, but in one embodiment of the present invention, the register 10 employs a first-in first-out method to sequentially store and delete data. Is performed.

That is, the storage area of the register 10 is fixed to a certain size, and the plate thickness measured by the entry thickness gauge 5 and the plate speed measured by the entry plate speedometer 3 are sequentially stored at every control period.

When the new sheet speed and sheet thickness data is input to the register 10, the entire data is moved forward one space in the storage area, and when the entire storage area is filled, the oldest data is deleted from the register 10. .

Integrating the speed of the rolled sheet material 7a in the process of moving the rolled sheet material 7a from the side thickness gauge 5 to the roll 1 with respect to the time from the side thickness gauge 5 to the roll 1 It is equal to the distance (x), which is expressed as follows.

x = ∫V _in (t) dt

Here, x is the distance from the entry thickness gauge 5 to the roll 1 and V _in (t) is the plate speed of the rolled sheet material 7a measured by the entry plate speedometer 3.

Since the control system for controlling the thickness of the rolled sheet material is a digital control system, the entry plate speed and the entry plate thickness are stored in the data storage register 10 of the digital control system at every control cycle. Therefore, in order to utilize [Equation 2] in the digital control system, the sampling time is Δt sign Expressed in the discrete time domain equation:

Since x is the distance x from the side thickness gauge 5 to the roll 1, it is a fixed constant. Therefore, the rolled plate member 7b in which the plate velocity Vn and the plate thickness Hn stored in the register 10 at k = n satisfying Equation 3 above are currently rolled by the roll 1. Is the platen velocity V _in and the plate thickness H _in .

That is, since the plate speed changes continuously during rolling, the moving distance of the rolled sheet material 7a is added up every control cycle, so that the plate thickness at the time point coinciding with the distance from the entry thickness gauge 5 to the roll 1 ( Hn) and the stand plate velocity Vn are extracted from the register 10.

The entry plate thickness Hn, the entry plate speed Vn, and the exit plate speed V _out measured by the exit plate speedometer 4 of the rolled sheet material 7b extracted from the register 10 are expressed in [Equation 1]. If it substitutes, the plate | board thickness of the current rolled sheet material 7b currently roll-molded by the roll 1 can be calculated. The calculated plate thickness is used to control the plate thickness in the plate thickness control system. On the other hand, reference numeral 6 denotes an exit thickness gauge, which measures the thickness of the rolled sheet member 7c after rolling molding.

Hereinafter, a method of controlling the inclination of the roll generated in the process of controlling the plate thickness will be described in detail.

3 is a view for explaining the operation of the roll shown in FIG.

Referring to FIG. 3, plate thickness control is performed while the rolls 1a and 1b are moved by driving the first hydraulic cylinder 8a and the second hydraulic cylinder 8b connected to both ends of the rolls 1a and 1b. . That is, the rolls 1a and 1b are moved up and down to adjust the thickness of the plate existing between the rolls 1a and 1b to correct the thickness error.

Here, even if the same position control is performed on the first hydraulic cylinder 8a and the second hydraulic cylinder 8b to control the thickness, the dynamic state of each hydraulic cylinder 8a and 8b is not the same, so that the first hydraulic cylinder 8a ) And the position of the 2nd hydraulic cylinder 8b shift | deviate, and as a result, the roll 1a and 1b incline.

If the inclination degree of the said roll 1a and 1b is excessive, roll 1a and 1b will be damaged. Therefore, while controlling the plate thickness, the inclination of the rolls 1a and 1b is simultaneously controlled to simultaneously perform thickness correction and roll inclination correction.

In addition, the operation is performed by adjusting the positions of the first hydraulic cylinder 8a and the second hydraulic cylinder 8b differently so that the rolls 1a and 1b are inclined slightly in accordance with the geometry of the surface of the rolled sheet material. In some cases. Here, the positions of the first hydraulic cylinder 8a and the second hydraulic cylinder 8b must be controlled to maintain the inclined angles of the rolls 1a and 1b during rolling.

When the plate thickness control is started, the first roll gap 9a and the second roll gap 9b of the rolls 1a and 1b at the starting moments are measured, and they are set to their respective initial roll gaps, and the difference between the two roll gaps is obtained. Initial inclination angles of 1a and 1b) are set. This is expressed as follows.

SetAngle = (Rollgap [1] -RollGap [2]) / RollLength

Here, SetAngle is the initial roll inclination angle, Rollgap [1] is the first initial roll gap 9a, RollGap [2] is the second initial roll gap 9b, and RollLength represents the lengths of the rolls 1a and 1b.

Subsequently, during the sheet thickness control, the first roll gap 9a and the second roll gap 9b of the rolls 1a and 1b are measured at every control cycle, and the difference between them is obtained to determine the current rolls 1a and 1b. Used at the angle of inclination of). This is expressed as follows.

ActAngle = (RollGap [1] -RollGap [2]) / RollLength

ActAngle represents the current roll tilt angle, RollGap [1] represents the first roll gap 9a for every control period, and RollGap [2] represents the second roll gap 9b for every control period.

In addition, in the course of performing rolling, the operator arbitrarily inputs the inclination angle command of the roll according to the flow and shape of the rolled sheet material 7a.

If the initial tilt angle set by the operator at the beginning of the rolling process is called SetTilt and the intermediate tilt angle input by the worker during the rolling process is called OperTilt, the intervention angle error caused by the operator's intervention is as follows.

 TiltErr = K × (SetTilt-OperTilt)

Here, the value K is a proportional constant multiplied to quickly correct the intervention angle error caused by the operator's intervention, and as the K value decreases, the intervention angle error may be smaller for the difference between the same initial tilt angle and the intermediate set tilt angle. have.

The first roll gap 9a and the second roll gap to be corrected when the initial roll inclination angle, the current roll inclination angle, and the intervention angle error are obtained by the above Equations 4, 5, and 6 The total tilt angle error of (9b) is calculated as follows.

AngleErr [1] = (SetAngle- ActAngle) / 2.0 + TiltErr

Here, AngleErr [1] represents the first total tilt angle error of the rolls 1a and 1b. In addition, an equation holds between the first total tilt angle error and the second total tilt angle error of the rolls 1a and 1b as follows.

AngleErr [1] = -AngleErr [2]

Here, AngleErr [1] is the first total tilt angle error (total left tilt angle error in FIG. 3) of the rolls 1a and 1b and AngleErr [2] is the second total tilt angle error (total right tilt angle error in FIG. 3). to be.

The plate thickness error is obtained by the difference between the estimated plate thickness (ActualGauge) and the target plate thickness (RefGauge), and the total inclination angle errors of the rolls 1a and 1b are added, so that the total control error is obtained as follows.

GapErr [1] = Ka × AngleErr [1] × Rolllength + Kt × (RefGauge-ActualGauge)

GapErr [2] = Ka × AngleErr [2] × Rolllength + Kt × (RefGauge-ActualGauge)

Where GapErr [1] and GapErr [2] are the first roll gap 9a error and the second roll gap 9b error to be corrected, respectively, Ka is a proportionality constant for the angular error, and Kt is a proportionality constant for the thickness error. to be. Ka and Kt are dimensionless constants and represent reflecting ratios reflecting each error in the control. For example, when the plate thickness error reflection is larger than the tilt angle error, Kt should be larger than Ka.

Meanwhile, the estimated plate thickness (ActualGauge) represents the plate thickness calculated by the process described with reference to FIGS. 1 and 2.

The plate thickness and roll gap error calculated by the above process is used to control the roll gaps 9a and 9b by the feedback system.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art having ordinary knowledge of the present invention will be able to make various modifications, changes, additions within the spirit and scope of the present invention, such modifications, changes and Additions should be considered to be within the scope of the following claims.

According to the plate thickness calculation method according to the present invention, there is an advantage that can grasp the accurate plate thickness error than the conventional method.

In addition, the sheet thickness calculation method according to the present invention and the method of calculating the roll gap error using the same has the advantage that it is possible to quickly calculate the inclination angle of the roll to control the roll stably and improve the thickness precision of the plate.

Claims (4)

Measuring the speed and thickness of the rolled sheet material before rolling; Sequentially storing data relating to the measured speed and thickness in a register; And Calculating the thickness of the rolled sheet material in the roll forming state from the data on the speed and thickness stored in the register and the data on the speed of the exit rolled sheet material after the roll forming by the roll. . 2. The method of claim 1, wherein the registers operate in a first-in first-out manner so that data storage and deletion are performed sequentially. Calculating an initial roll tilt angle and a current roll tilt angle from the first roll gap and the second roll gap; Calculating an intervention angle error using an initial set tilt angle set at the beginning of the rolling process and an intermediate set tilt angle according to an input during the rolling process; Calculating a total tilt angle error from the calculated initial roll tilt angle, current roll tilt angle, and intervention angle error; Calculating a roll gap error from the total tilt angle error and the sheet thickness error. The method of claim 3, wherein the plate thickness error is calculated by the difference between the thickness of the surface plate and the thickness of the rolled sheet material in the roll forming state, The thickness of the rolled sheet material in the roll forming state, Measuring the speed and thickness of the rolled sheet material before rolling; Sequentially storing data relating to the measured speed and thickness in a register; And Calculating the thickness of the rolled sheet material in the roll forming state from the data concerning the speed and thickness stored in the register and the data of the speed of the exit rolled sheet material after the roll forming by the roll. Output method.

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