KR100660204B1 - Thickness control apparatus in rolling mill - Google Patents

Abstract

A system and a method for controlling rolling thickness in real-time by dynamically varying a gain of a roll force automatic gauge control according to a strip thickness deviation at output sides of respective stands of a finish rolling mill, thereby controlling an adjusting amount of a roll gap are provided. In a rolling thickness control system using a roll force automatic gauge control in a multistage rolling facility with F1 to F7 stands, the rolling thickness control system comprises: a deviation calculation part(110) a strip thickness deviation(ÝÈh) at output sides of the stands using set roll force values(Fci) and set roll gap values(Sci) of the respective stands transmitted from a high-level computer, and roll force measurement values(Fsi) and roll gap measurement values(Ssi) measured at output sides of the respective stands; a roll gap adjusting amount calculation part(120) for calculating a roll gap adjusting amount of the roll force automatic gauge control using the calculated strip thickness deviation(ÝÈh) and a gain of the roll force automatic gauge control; a thickness detection part(130) for detecting output side strip thickness values at the output sides of the stands, and calculating a deviation(ÝÈhx) between the detected output side strip thickness values and a preset strip thickness value to output the calculated deviation(ÝÈhx); a gain adjusting part(140) for adjusting a gain of the roll force automatic gauge control in proportion to the strip thickness deviation(ÝÈhx) outputted from the thickness detection part; an adding-up part(150) for adding up the roll gap adjusting amount and the set roll gap values to output a renewed roll gap(S^*); and a control part(160) for controlling strip thickness according to the roll gap(S^*).

Description

Thickness Control Apparatus in Rolling Mill}

1 is a block diagram of a rolling thickness control device using a conventional roll force AGC.

2 is a block diagram of a rolling thickness control device using a roll force AGC according to an embodiment of the present invention.

3 is a graph showing a gain adjustment ratio of a roll force AGC according to an embodiment of the present invention.

 Explanation of symbols on the main parts of the drawings

110: plate thickness deviation calculation unit 120: roll gap adjustment amount calculation unit

130: thickness detection unit 140: gain adjustment unit

150: adder 160: control unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling thickness control apparatus, and in particular, an apparatus for controlling the rolling thickness by adjusting a roll gap by dynamically changing a gain of Roll Force AGC (Roll Force Automatic Gauge Control) in proportion to the rolling plate thickness deviation at the exit of the finishing mill. It is about

A continuous casting machine in a steel mill casts molten steel contained in a converter into a slab shape, and then heats the slab into a hot rolled steel sheet having a thickness of about 45 mm in a rough rolling mill after heating for about 3 hours in a heating furnace. The hot rolled steel sheet that passes through the rough rolling mill cuts the fish tail portion of the stern end by a crop shear to improve the flowability, and then the edge heater and the bar heater. Bar Heater makes the temperature uniform. The hot rolled steel sheet in the uniform state is quickly moved and rolled into a hot rolled sheet having a thickness of up to 1.2 mm in the finishing mill. The rolled hot rolled steel sheet is wound up again in the form of a coil by a downcoil and shipped.

In the rolling process in the finishing mill comprised of the tandem multi-stage rolling mill, the rolling conditions of each stand are set before rolling before the rolling of the hot rolled steel sheet according to the thickness, width, and steel type. When rolling starts according to the set rolling conditions, the rolling speed and the roll gap are controlled by real-time feedback control. Even if some errors occur in the preset rolling conditions as described above, the rolling conditions at each stand are optimized by the real-time feedback control.

However, when the error of the set rolling conditions is large, it is difficult to optimize the rolling conditions such as a large thickness deviation of the tip of the steel sheet is generated by real time feedback control. Therefore, it is important not only to properly set the rolling conditions of each stand, but also to optimally adjust the roll reduction force, roll gap, etc. according to the thickness deviation after rolling.

As a real-time feedback control method of the conventional finishing mill, Roll Force AGC (Roll Force Automatic Gauge Control) is. The roll force AGC is a method of controlling the estimated thickness of the starting point as a reference value, and is a method of controlling the thickness deviation between the starting point and the present time of the rolling force AGC to be zero, and controlling the two thickness deviations. In order to calculate the roll gap adjustment amount, the roll gap control amount is used to control the roll gap of the rolling mill.

1 is a block diagram of a rolling thickness control device using a conventional roll force AGC. As shown in FIG. 1, the conventional rolling thickness control apparatus includes a roll force setting value (Fci) and a roll gap setting value (Sci) of the i-th stand 50 transmitted from an upper computer (not shown), and the i-th. Plate thickness deviation unit 10 for receiving the roll force measured value Fsi and the roll gap Ssi measured at the exit of the stand 50 and calculating the exit plate thickness deviation Δh of the stand 50, The roll gap adjustment amount calculation unit 20 for calculating the roll force AGC roll gap adjustment amount using the calculated plate thickness deviation Δh and the gain of the roll force AGC (G _RF ), the roll gap adjustment amount and the set roll gap setting value a controller 40 for controlling the plate thickness of the i-th stand in accordance with the summation unit 30 and the updated rolgaep (S ^*) and outputting a (Sci) of rolgaep (S ^*) updated by summing the.

In the conventional rolling thickness control apparatus shown in FIG. 1, the roll gap adjustment amount calculation unit 30 calculates the roll force AGC roll gap adjustment amount using the plate thickness deviation Δh as shown in Equation 1 below.

[Equation 1]

Where M is the milling constant, Q is the plasticity coefficient, and G _RF is the gain of Rollforce AGC.

In the conventional rolling thickness control device, since the gain G _RF of the roll force AGC is fixed, the rolling thickness is stabilized due to changes in steel grade, thickness, temperature, etc. of the rolled steel sheet. That is, since the gain value (G _RF ) of the conventional Roll Force AGC is initially set to a fixed value and the rolling thickness is controlled by using only the exit plate thickness deviation, the rolling thickness may not be controlled in real time when a quality control abnormality occurs. It was difficult.

Therefore, the present invention is proposed to solve the conventional problem that the roll thickness AGC is fixed in real time by controlling the roll thickness in controlling the rolling thickness by using the existing roll force AGC, each stand of the finishing mill It is an object of the present invention to provide an apparatus and method for controlling the rolling thickness in real time by controlling the roll gap adjustment amount by dynamically varying the gain of the roll force AGC according to the plate thickness deviation at the exit side of the substrate.

Rolling thickness control apparatus of the present invention for achieving the above object, in the rolling thickness control apparatus using a roll force AGC in a multi-stage rolling equipment having a F1 ~ F7 stand,

Using the roll force setting value and the roll gap setting value of each stand transmitted from the host computer, and the roll force measurement value and the roll gap measurement value measured at the exit side of each stand, the exit plate thickness deviation (Δh) of the stand is calculated. A deviation calculator; A roll gap adjustment amount calculation unit configured to calculate a roll force AGC roll gap adjustment amount using the calculated plate thickness deviation? H and the gain of the roll force AGC; A thickness detecting unit detecting the exit plate thickness at the exit side of the stand and calculating and outputting a deviation (Δh _X ) from a preset plate thickness; A gain adjusting unit for adjusting the gain of the roll force AGC in proportion to the plate thickness deviation Δh _X outputted from the thickness detecting unit; Summing unit for outputting the rolgaep (S ^*) updated by adding the adjustment amount and the set rolgaep rolgaep set value and a control unit for controlling the plate thickness according to rolgaep (S ^*) of the update.

In one embodiment of the present invention, the thickness detection unit detects the plate thickness using an X-ray.

In one embodiment of this invention, the said roll gap adjustment amount calculation part calculates a roll gap adjustment amount using the following formula.

[Equation]

(Where M is the milling constant, Q is the plasticity coefficient, ΔS is the roll gap adjustment amount, and Δh is the plate thickness deviation)

In one embodiment of the present invention, the gain adjusting unit adjusts the gain of the roll force AGC using the following equation.

[Equation]

Where G _RF ^* is the gain of the RollForce AGC after adjustment, G _RF is the gain of the AGC before adjustment, and the gain adjustment rate is 0 μm for the exit plate thickness deviation (Δh _X ) for the F4 and F5 stands. Is 140% of the AGC gain (G _RF ) before the adjustment, 120% at 30 μm, 100% at 50 μm, 95% at 80 μm, 90% at 150 μm or more, and the F6 and F7 stands. When the exit plate thickness deviation (Δh _X ) is 0 μm, it is 150% of the AGC gain (G _RF ) before the adjustment, 130% at 30 μm, 100% at 50 μm, 95 at 80 μm. %, 90% when it is over 150㎛)

Here, the gain adjustment ratio is determined using interpolation for values between the five outgoing plate thickness deviations (Δh _X ) values indicated above.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

2 is a block diagram of a rolling thickness control device according to an embodiment of the present invention. The rolling thickness control apparatus of the present invention is applied to a multi-stage rolling facility including a roll force AGC. As shown in FIG. 2, the rolling thickness control apparatus of the present invention uses the roll force setting value and the roll gap setting value of the stand transmitted from the host computer, and the roll force measurement value and the roll gap measurement value measured at the exit side of the stand. The roll force AGC roll gap adjustment amount is calculated using the deviation calculator 110 for calculating the exit plate thickness deviation Δh of the stand, the calculated plate thickness deviation Δh, and the gain of the roll force AGC. The roll gap adjustment amount calculation unit 120 detects the exit plate thickness at the exit side of the stand, and calculates and outputs a deviation (Δh _X ) from the preset plate thickness from the thickness detection unit 130 and the thickness detection unit 130. the output thickness deviation (△ h _X) in proportion to the roll gain adjuster 140 that adjusts the gain of the force AGC, the rolgaep adjustment amount with the set roll gap settings updated rolgaep by summing the values (S ^*) in the An output unit 150 for outputting and the updated unit The control unit 160 for controlling the plate thickness in accordance with the roll gap (S ^* ).

The roll gap deviation calculation unit 110 receives a roll force setting value Fci and a roll gap setting value Sci set in advance according to the type, thickness, length, temperature, etc. of the steel sheet from an upper computer (not shown). In addition, the roll gap deviation calculation unit 100 receives the roll force measurement value Fsi and the roll gap measurement value Ssi measured from the roll force and the roll gap measurement unit 180 installed in the specific stand 170. Subsequently, the roll gap deviation calculating unit 100 uses the roll force deviation (Fsi-Fci) and the roll gap deviation (Ssi-Sci) based on the exit thickness at the time of starting the roll force AGC 200. Similarly, the deviation (Δh) of the exit plate thickness is calculated.

[Equation 1]

h = Fsi / M + Ssi-k

h ₀ = Fci / M + Sci-k

Here, h and S are the exit plate thickness and the roll gap, h ₀ and S ₀ are the plate thickness and the roll gap at the start of the roll force AGC, and M is the density constant.

From the above formula 1, the outgoing plate thickness deviation? H is calculated as shown in the following formula 2.

[Equation 2]

Δh = hh ₀ = (Fsi-Fci) / M + (Ssi-Sci)

If Equation 2 is converted into a relationship with the plasticity factor Q, the following Equation 3 is obtained.

[Equation 3]

As described above, the plate thickness deviation calculation unit 110 calculates the exit plate thickness deviation Δh of the stand using Equations 1 to 3.

The roll gap adjustment amount calculation unit 120 calculates the roll gap adjustment amount (ΔS ′) of the roll force AGC by using Equation 4 below using the outgoing plate thickness deviation (Δh) calculated as described above.

[Equation 4]

Where M is the milling constant, Q is the plasticity coefficient, DELTA S 'is the roll gap adjustment amount, DELTA h is the plate thickness variation, and G _RF ^* is the gain of the roll force AGC.

As in Equation 4, the roll gap adjustment amount ΔS 'of the roll force AGC is determined according to the plate thickness deviation Δh and the gain G _RF ^* of the roll force AGC. The gain G _RF ^* of the roll force AGC is adjusted by the gain adjusting unit 140. Hereinafter, adjustment of the gain G _RF ^* of the roll force AGC in the gain adjusting unit 140 will be described.

First, a thickness detecting unit 130 is provided on the exit side of the stand and calculates the deviation Δh _X between the exit plate thickness measurement value and the preset plate thickness setting value. The thickness detection unit 130 preferably uses an X-ray thickness meter.

The exit plate thickness deviation Δh _X outputted from the thickness detector 130 is input to the gain adjuster 140. The gain adjusting unit 140 adjusts the gain G _RF ^* of the roll force AGC according to the plate thickness deviation Δh _X. At this time, the gain (G _RF ^* ) of the roll force AGC is calculated as in Equation 5 below.

[Equation 5]

Where G _RF ^* is the gain of Rollforce AGC after adjustment, G _RF is the gain of AGC before adjustment, and the gain adjustment rate is 0 μm when the exit plate thickness deviation (Δh _X ) is F4 and F5 stand. 140% of the AGC gain (G _RF ) before the adjustment, 120% at 30 μm, 100% at 50 μm, 95% at 80 μm, 90% at 150 μm or more, and for F6 and F7 stands. When the exit plate thickness deviation (Δh _X ) is 0 μm, it is 150% of the AGC gain (G _RF ) before the adjustment, 130% at 30 μm, 100% at 50 μm, and 95% at 80 μm. When the outgoing plate thickness deviation (Δh _X ) is a value between the above values, the gain adjustment ratio is calculated by applying an interpolation method. In the interpolation method applied to the present invention, it is preferable that the five deviation values and the corresponding gain adjustment ratios have a linear relationship, and the interpolation method is applied to the values therebetween. For example, 150% at 0 μm, 130% at 30 μm, and 143.3% at 10 μm (30 μm: 20% = 10 μm: x, x = 6.7%, therefore, 150-6.7). = 143.3%), which is 136.7% at 20 µm (30 µm: 20% = 20 µm: x, x = 13.3%, and therefore 150-13.3 = 136.7%).

Hereinafter, the gain ratio of the roll force AGC according to the plate thickness deviation Δh _X will be described in more detail.

The gain adjustment ratio according to the present invention is calculated by the AGC control computer for each stand, the roll force AGC is intended to maintain the same state based on the roll force set for each stand in the case of a small thickness variation disturbance (e.g. cooling water) , Air, noise, etc.) and the gain adjustment rate is different for each stand to converge in the direction of decreasing thickness deviation.

In the present invention, as an embodiment, as shown in the following table, the criteria for outgoing plate thickness deviation (Δh _X ) were largely divided into five, 0, 30, 50, 80, and 150 μm. This division is only an example and may be classified in various ways. In addition, depending on the tolerance management level of the plate thickness can be divided into narrower intervals so that the variation in thickness can be controlled within a few ㎛.

Applicants of the present invention determined the gain adjustment rate for each stand as described above through repeated experiments in Roll Force AGC with respect to five reference plate thickness deviation (Δh _X ) as described above.

[table]

Division △ △ h _X 0 30 50 80 150 F4 + 140 120 100 95 90 - 140 120 100 95 90 F5 + 140 120 100 95 90 - 140 120 100 95 90 F6 + 150 130 100 95 90 - 150 130 100 95 90 F7 + 150 130 100 95 90 - 150 130 100 95 90

In the above table, +/- indicates whether the thickness deviation Δh _X is positive or negative. For example, if the thickness setting value is 2 m and the thickness detection value is 3 m, the deviation value is +1 m, and if the thickness detection value is 1 m, the deviation value is -1 m. Therefore, as shown in the above table, it can be seen that the gain adjustment ratio is the same regardless of whether the thickness deviation Δh _X is +/− for each stand.

Based on the repetitive experiment described above, applying the gain adjustment rate of the Roll Force AGC according to the plate thickness deviation Δh _X detected at the exit side for each stand is shown in FIG. 3. That is, as shown in FIG. 3, in the case of the F4 and F5 stands, when the exit plate thickness deviation (Δh _X ) is 0 μm, it is 140% of the AGC gain before adjustment, at 30 μm, 120% and 50 μm. 100%, 95% for 80 μm, 90% for 150 μm or more, 150% of AGC gain before adjustment when the exit plate thickness deviation (Δh _X ) is 0 μm for F6 and F7 stands, 30 130% for μm, 100% for 50 μm, 95% for 80 μm, 90% for 150 μm or more, and update values by calculating and applying a gain adjustment rate using interpolation as described above. Calculate the gain (G _RF ^* ) of the rollforcing AGC.

As described above, the roll gap adjustment amount calculation unit 120 calculates the roll gap adjustment amount by applying the gain G _RF ^* of the newly updated roll force AGC as described above. The calculated roll gap adjustment amount is input to the adder 150, and the adder 150 adds the input roll gap adjustment amount and the preset roll gap setting value to control the new roll gap S ^* . Will output

The control unit 160 controls the rolling thickness by controlling the rolling force of the stand according to the new roll gap (S ^* ).

Figure 4 shows the thickness profile of the steel sheet before and after performing the rolling thickness control according to the present invention. 4 (a) is a steel sheet thickness profile before applying the present invention, and FIG. 4 (b) is a steel sheet thickness profile after applying the present invention.

Comparing Fig. 4 (a) and Fig. 4 (b), it can be seen that Fig. 4 (a) is a non-uniform thickness of the steel sheet and a serious variation in the thickness control. However, in the case of Figure 4 (b) it can be seen that the thickness of the steel sheet is maintained substantially constant.

The detailed description and the contents of the drawings described above exemplarily describe preferred embodiments of the control of the rolling thickness of the steel sheet according to the present invention, but the present invention is not limited thereto. In particular, the roll force AGC applied in the present invention may apply various techniques without departing from the technical spirit of the present invention. Accordingly, the scope of the present invention should not be determined by the above description and drawings, but should be determined by the appended claims.

According to the present invention, fast rolling thickness control is possible in real time by adjusting the gain of the roll force AGC in accordance with the plate thickness variation of the steel sheet rolled to the exit side of each stand in the finishing mill.

Claims (4)

In the rolling thickness control apparatus using Roll Force AGC in a multi-stage rolling facility having a F1 to F7 stand, Using the roll force setting value and the roll gap setting value of each stand transmitted from the host computer, and the roll force measurement value and the roll gap measurement value measured at the exit side of each stand, the exit plate thickness deviation (Δh) of the stand is calculated. A deviation calculator; A roll gap adjustment amount calculation unit configured to calculate a roll force AGC roll gap adjustment amount using the calculated plate thickness deviation? H and the gain of the roll force AGC; A thickness detecting unit detecting the exit plate thickness at the exit side of the stand and calculating and outputting a deviation (Δh _X ) from a preset plate thickness; A gain adjusting unit for adjusting the gain of the roll force AGC in proportion to the plate thickness deviation Δh _X outputted from the thickness detecting unit; An adder configured to add the roll gap adjustment amount and the set roll gap setting value to output an updated roll gap (S ^* ); And A control unit controlling the plate thickness according to the roll gap S ^* ; Rolling thickness control device comprising a. The method of claim 1, The thickness detecting unit is a rolling thickness control device, characterized in that for detecting the plate thickness using an X-ray. The method of claim 1, The roll gap adjustment amount calculating unit calculates the roll gap adjustment amount using the following formula. [Equation]

(Where M is the milling constant, Q is the plasticity coefficient, ΔS is the roll gap adjustment amount, and Δh is the plate thickness deviation) The method of claim 1, The gain adjusting unit is a rolling thickness control device, characterized in that for adjusting the gain of the roll force AGC using the following formula. [Equation]

(Wherein, G is the gain of the _RF ^* Roll Force AGC after the adjustment, G _RF in the case of the gain, the gain update ratio is F4 and F5 of the stand AGC prior to adjusting the exit side thickness difference (△ _X h) When the work 0㎛ 140% of the G _RF , 120% at 30㎛, 100% at 50㎛, 95% at 80㎛, 90% at 150㎛ or more, the exit plate thickness deviation (△ F6 and F7 stands) h _X ) is 150% of the G _RF at 0 μm, 130% at 30 μm, 100% at 50 μm, 95% at 80 μm, and 90% at 150 μm or more).

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