KR100804240B1 - The Method for Correcting Gutter of Strip in Continuous Galvanizing Line - Google Patents

Abstract

The method for automatically calibrating strip bending of the present invention is a process control computer (36, SCC) when there is a steel type change and thickness change between the welded line and the following coil of the strip 13 entering the zinc port (Zinc Port) Comparing the intermesh amount of the strip thickness and the carbon content set in advance and predicted with each other and outputting the intermesh amount data corresponding to the difference to the motor controller 31; When the line tension of the strip 13 is changed, the instrumentation control computer 37 (DDC) finds the intermesh amount value for the preset tension change and outputs the intermesh amount data to the motor controller 31. Making; The motor controller 31 drives the motor 32 through the intermesh amount and distance data input at each step, and according to the detection signal of the potentiometer 34 which is a distance sensor, a stabilizing roll 12. Adjusting the half curvature of the strip 13 by moving it back and forth by the input intermesh amount data; In the case where the widthwise plating amount difference of the strip 13 occurs despite the adjustment of the bending in the above step, when the coating gauge 38 calculates the plating amount difference and exceeds a predetermined value, the bending of the strip 13 accordingly By calculating the degree and transmitting it to the motor controller 31, it comprises the step of readjusting the semi-curve of the strip 13, because the semi-curve of the strip is automatically corrected around the weld where the semi-curve is generated at the air knife position and when the tension changes Accordingly, the difference in the plating amount in the width direction due to the decrease in the semi-curvature is reduced, and the manual operation is not performed according to the operator's experience, and the deviation between the workers is zeroed. There is an advantage.

Plating amount, Stabilizing roll, Sink roll, Potentiometer, Air knife, Bending, Intermesh

Description

The Method for Correcting Gutter of Strip in Continuous Galvanizing Line

1 is a configuration diagram of the peripheral equipment related to the air knife (Air Knife) of the continuous plating line to which the present invention is applied,

Figure 2 is a cross-sectional view of a stabilizing roll assembly (Stabilizing Roll Assembly) used in the present invention,

3 is a system configuration according to an embodiment of a method for automatically correcting strip bending of the present invention;

Figure 4 is a flow chart showing the operation of one embodiment of a method for automatically correcting strip bending of the present invention.

<Explanation of symbols for the main parts of the drawings>

11: Sink Roll 12: Stabilizing Roll

13: Strip 14: Air Knife

31: motor controller 32: motor

33: gear 34: potentiometer

36: process control computer (SCC) 37: instrumentation control computer (DDC)

38: Coating Gauge

The present invention relates to a method for automatically correcting strip bending, and more particularly, to the thickness, steel grade, and tension of a strip in a zinc pot (hereinafter referred to as a "ink pot") installed in a continuous electroplating line (CGL). When (Tension) is changed, the plating amount variation in width direction occurs in Air Knife due to the semi-curvature, so in order to prevent this, the tension or width direction variation amount is changed during thickness and steel type change or online. The present invention also relates to a method for automatically correcting strip bending, which reduces and prevents strip bending, thereby ensuring good plating.

Generally, in the hot dip galvanizing line, in order to control the plating thickness, an air knife is installed at the exit of the zinc port to adjust the plating amount. Air Knife is a facility that consists of two horizontal nozzles to preheat zinc (up to 400 ° C) to scrape zinc from the strip surface.

FIG. 1 shows an air knife periphery, in which a strip 13 passing through a furnace wraps around the sink roll 11 immersed in a bath when passing through a zinc bath, passing the front and back stabilizing roll 12. The amount of plating is adjusted by the air preheated by the front and rear air knife 14 after that.

2 shows a stabilizing roll 12 that adjusts the half-curve when half-curvature occurs in the strip.                         

Conventional methods for controlling the plating amount include a feedforward control method, a feedback control method, and a plating amount control method using a one-point distance sensor when the plating amount of the strip is changed.

Conventional control method is generally installed on the top of the air knife 14 when the plating thickness changes, the sensor having a predetermined interval with the air knife 14 and feed back the value measured by the sensor to the air knife 14 before, The distance of the rear air knife 14 was kept constant.

However, since this control method has a focus on the feedback function, it is impossible to directly control when the thickness of the steel sheet changes, so that there is an area that cannot be controlled due to the variation of the thickness. there was.

In addition, a change in thickness and steel grade of the strip 13 or a change in tension results in bending of the strip 13 in the width direction of the strip 13. As a result, the distance in the width direction is changed so that the distance can be well controlled by the one-point sensor. There was no problem.

In addition, the conventional control method assumes that the plating amount is uniform in the width direction of the strip 13, and has a main purpose of minimizing the difference in the amount of plating on the front and back surfaces. Had a considerable problem.

Therefore, when the steel grade and thickness change and the line tension change, the operator depends on the visual and manual work experiences with the naked eye. In this case, the quick response is delayed, and the deviation between the workers is also delayed, so the semi-correction work is delayed. There was a problem that the plating amount variation is excessively generated.

The present invention has been made to solve the above problems, for predicting the bending occurs when the thickness of the strip or steel type changes, the welding before passing through the air knife to adjust the stabilizing roll according to the degree of bending occurs, Adjusts the stabilizing roll in anticipation of the bending generated even when the cooling tower tension is changed during the on-line, and the difference in the width plating amount generated when the bending remains even after the first calibration operation is performed. It is an object of the present invention to provide a method for automatically correcting strip bending by adjusting the stabilizing roll by calculating the degree of bending through

Method for automatically correcting the strip bending of the present invention having the above object, in the method for straightening the strip bending of the continuous plating equipment line,

In the case of steel grade change and thickness change between the welded wires and the following coils of the strip 13 entering the zinc port, the process control computer 36 (SCC) is predicted and set in advance to set the strip thickness and carbon content. Comparing the intermesh amounts with respect to each other and outputting the intermesh amount data corresponding to the difference to the motor controller 31;

When the line tension of the strip 13 is changed, the instrumentation control computer 37 (DDC) finds the intermesh amount value for the preset tension change and outputs the intermesh amount data to the motor controller 31. Doing;

The motor controller 31 drives the motor 32 through the intermesh amount and distance data input at each step, and according to the detection signal of the potentiometer 34 which is a distance sensor, a stabilizing roll 12. Adjusting the half curvature of the strip 13 by moving it back and forth by the input intermesh amount data;

In the case where the widthwise plating amount difference of the strip 13 occurs despite the adjustment of the bending in the above step, when the coating gauge 38 calculates the plating amount difference and exceeds a predetermined value, the bending of the strip 13 accordingly By calculating the degree and transmitting it to the motor controller 31, it characterized in that it comprises a step of readjusting the half-curvature of the strip (13).

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration of a preferred embodiment according to the method for automatically correcting strip bending of the present invention.

3 shows a halftone calibration system according to the present embodiment.

As shown, the process control computer 36 (SCC) having information on the strip thickness and steel grade of the line and trailing coils and the instrumentation control computer 37 (DDC) having information on the cooling tower tension and the plating amount data of the strip Coating gauges 38 and 38 are respectively connected to the motor controller 31.

In addition, the motor controller 31 is connected to the motor 32 for driving the stabilizing roll 12 back and forth, and the motor 32 is provided on both sides of the roll.

And the gear 33 which converts the rotational force of the motor 32 into linear motion so that a roll moves back and forth is provided.

At a predetermined point on one side of the gear shaft, as a distance sensor, a potentiometer 34 (potentiometer) 34, which is a potentiometer in which the movement distance is converted into voltage, is provided.

A method of correcting a semi-bending upon thickness change and steel grade change of the strip 13 according to the semi-automatic straightening method of a preferred embodiment of the present invention will be described.

First, when the weld type passes through the air knife 145, when the steel grade or thickness changes, the intermesh data of the wire and the trailing coil is calculated according to the amount of intermesh that is the predicted correction amount according to the degree of bending after the weld passes through the zinc port. When a difference occurs when comparing with each other, the distance is controlled as much as the difference occurrence distance.

The predicted intermesh amount is determined according to the carbon content and thickness according to the Gutter Theory based on field operation performance and elastoplastic theory.

Intermesh content = 22.4 + 43.4 * (C) content-5.62 * Strip thickness ---- (Gutter Theory)

The regression equation

Intermesh amount = 22.4 + 43.4 composition-5.62 thickness

Predictor                                          Coef SE Coef T P Constant                                          22.3867 0.0588 380.50 O.OOO Composit                                          43.3769 0.2435 178.13 O.OOO Thickness                                          -5.61882 0.02991 -187.88 O.OOOO

S = 0.2557 R-Sq = 99.9% R-Sq (adj) = 99.9%

Analysis of Variance

Source                                          DF SS MS F P Regression                                          2 4382.0 2191.0 33514.50 0.000 Residual Error 60 3.9 0.1 Total                                          62 4385.9 2191.1 33514.50 0.000

According to the carbon content and strip thickness, the amount of intermeshing intermesh is based on the Gutter Theory as follows, according to the size of the strip and the table according to the carbon content. It was made up.

Halftone table division T≥0.2 T≤0.3 T≤0.5 T≤0.7 T≤1.0 T≤1.4 T≤1.9 T≤2.7 T≥3.5 (C) ≤ 0.003% 21 21 20 19 17 15 12 7 3 (C) ≤ 0.01% 22 21 20 19 17 15 12 8 3 (C) ≤ 0.03% 22 22 21 20 18 16 13 9 4 (C) ≤ 0.06% 24 23 22 21 19 17 14 10 5 (C) ≤ 0.1% 26 25 24 23 21 19 16 12 7 (C) ≤ 0.2% 30 29 28 27 25 23 20 16 11 (C)> 0.2% 39 38 37 36 34 32 29 25 20

In addition, when the process of adjusting the bending when the cooling tower tension (Cooling Tower Tension) changes during the operation, the degree of bending is changed according to the tension change, that is, in the state where the strip bending is corrected by the stabilizing roll 12 If the cooling tower tension is raised, the top grain is generated on the strip, and moving out the stabilizing roll 12 as shown in the following tension table, while lowering the cooling tower tension, the lower valley is generated. Moving In automatically corrects the halftone.                     

Tension table Tension car > △ (+1) ＞ △ (+0.5) ≤ △ (± 0.5) ＞ △ (-0.5) ≥ △ (-1.0) Intermesh amount △ (-4) △ (-2) △ (0) △ (+2) △ (+4)

When the half-curve operation is performed after the half-correction operation as described above, since the plating amount difference occurs in the width direction of the strip 13, the degree of bending must be predicted as follows through the width-wise plating amount difference.

First, the plating amount difference (ΔCW) of the center CENTER portion is calculated from the average value of the width direction WS and DS with respect to the front and rear surfaces of the strip 13.

△ CW (Front) = Center-1/2 (WS + DW)

△ CW (rear) = 1/2 (WS + DW)-Center

Next, if the plating amount difference ΔCW is larger than the predetermined value 1g by taking a smaller value among the above values, the plating amount difference ΔCW is converted into distance data.

The plating amount in the line is expressed as follows according to the air knife plating amount theory.

CW = 52.0 + 11.5 Distance-0.439 Height + 1.05 Pressure ---- Air Knife Plating Theory

In the above, converting the plating amount difference in the width direction (WS, DS and CENTER) into a distance is expressed as follows.

△ CW = 11.5 * △ Distance

As described above, the process control computer 36, the instrumentation control computer 37, and the coating gauge 38 of the system obtain the inlet distance of the stabilizing roll 12 based on each input information according to the situation. The change distance data is transmitted.

The motor controller 31 rotates the motor 32 from the input data, and through the gear 33, the motor rotational force is changed to linear movement before and after, so that the stabilizing roll 12 is adjusted for distance.

At this time, the driving of the motor 32 is controlled by a potentiometer 34, which is a distance sensor. The potentiometer 34 converts a voltage into a distance as a potentiometer and detects this when the roll is moved by a set distance. Stop motor rotation by

For example, when explaining each of the above processes,

First, when the thickness of the preceding coil and the following coil is changed from 0.4t to 0.6t and the carbon content is changed from 0.02% to 0.03%, the drawing distance of the stabilizing roll 12 to the preceding coil according to the semi-curved table The amount of phosphorus intermesh is 21mm (Dold), whereas the inlet distance of the changed trailing coil is 20mm (Dnew).

Therefore, the distance of the stabilizing roll 12 should be adjusted by ΔDistance = Dnew-Dold = 20-21 = -1 mm. Therefore, the data is transmitted to the motor controller 31 so that the stabilizing roll 12 is moved by the motor 32.

The distance that the roll is moved is controlled by the potentiometer 34. When the voltage is set at a distance of 0.1 mm per 0.1 Volt, the 1 Volt voltage corresponding to the 1 mm becomes the set voltage, so that the potentiometer 34 has a voltage of 1 Volt. The motor controller 31 stops the motor drive when the motor controller 31 detects this, and the semi-bending correction operation is completed.

In addition, when the tension is changed during the on-line and the work is changed to 2.3 tons and then changed to 2.9 tons, the tension change difference depends on the tension table.

ΔTension = Tnew-Told = 2.9-2.3 ton = 0.6 ton, the intermesh amount, which is the draw distance difference of the stabilizing roll 12, becomes -2 mm, and the semi-curve calibration work is performed in the above process.

In addition, even in the case where the widthwise plating amount difference occurs due to the widthwise bending in the online, the bending correction is performed through the following table.

division WS CENTER DS Front 90 120 90 back side 90 70 90

Front CW = CENTER-1/2 (WS + DW) = 120-1/2 (90 + 90) = 30

Rear of CW = 1/2 (WS + DW)-CENTER = 1/2 (90 + 90)-70 = 90-70 = 20

△ CW = Minimum (| △ CW front |, | △ CW back |) = Minimum (| 30 |, | 20 |)> 1g

Since the difference in plating amount is more than 1g, the stabilizing roll 12 is moved to correct the bending by the amount corresponding to the difference in plating amount.

△ CW = 11.5 * △ Distance

△ Distance = 20 / 11.5 = 1.7mm

4 is a flowchart of the present embodiment, and therefore, the description thereof will be omitted below.

In the method of automatically correcting the strip bending of the present invention acting as described above, the difference in the amount of plating in the width direction due to the decrease in the bending decreases as the bending of the strip is automatically corrected around the welded portion where the bending occurs at the air knife position and when the tension is changed. By eliminating the manual operation according to the operator's experience, the deviation between the workers is zeroed, and thus, there is an advantage that a good plating can be produced according to the marked reduction in the plating amount variation of the hot-dip plated product.

Claims (1)

In the method of correcting the strip bending of the continuous plating equipment line, In the case of steel grade change and thickness change between the welded wires and the following coils of the strip 13 entering the zinc port, the process control computer 36 (SCC) is predicted and set in advance to set the strip thickness and carbon content. Comparing the intermesh amounts with respect to each other and outputting the intermesh amount data corresponding to the difference to the motor controller 31; When the line tension of the strip 13 is changed, the instrumentation control computer 37 (DDC) finds the intermesh amount value for the preset tension change and outputs the intermesh amount data to the motor controller 31. Making; The motor controller 31 drives the motor 32 through the intermesh amount and distance data input at each step, and according to the detection signal of the potentiometer 34 which is a distance sensor, a stabilizing roll 12. Adjusting the half curvature of the strip 13 by moving it back and forth by the input intermesh amount data; In the case where the widthwise plating amount difference of the strip 13 occurs despite the adjustment of the bending in the above step, when the coating gauge 38 calculates the plating amount difference and exceeds a predetermined value, the bending of the strip 13 accordingly A method for automatically correcting strip bounce, characterized in that it comprises a step of recalculating the bounce of the strip 13 by calculating the degree and transmitting it to the motor controller 31.

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