KR20020087213A - Method for controlling local shape of ultra-thin steel strip with high strength in cold rolling machine - Google Patents

Abstract

The present invention relates to a high strength ultra-thin material local shape control method in a continuous rolling mill, and more particularly, to a high strength ultra-thin material in a continuous rolling mill to prevent a shape defect locally occurring in the center of the steel sheet during cold rolling of ultra-thin material of less than 0.23 mm thick It relates to a local shape control method.

To this end, the present invention receives the flatness (ε _i ) of the cold rolled ultrathin material 1 from the shape detector (5) base of the continuous rolling mill to calculate the shape deviation (Δε) from the shape control unit 6 to work the shape defect A roll is mounted on the upper surface of the ultra-thin material and is mounted on the upper work roll cooling device 10 for spraying cooling air for cooling the upper work roll 2 and the lower surface is installed to cool the lower work roll 2 '. It provides a method of controlling the local shape of the cold rolled ultrathin material by using a lower work roll cooling device 11 for spraying cooling water.

As described above, the present invention calculates the shape detection value of the final stand in the shape control unit and then recognizes the shape defect and controls the roll thermal crown by cooling the roll cooling device installed on the exit side of the final stand based on the width of the steel sheet of the high strength ultra-thin material. There is an effect of reducing the pocket wave in the direction.

Description

Local shape control method of high strength ultra-thin material in continuous rolling mill {METHOD FOR CONTROLLING LOCAL SHAPE OF ULTRA-THIN STEEL STRIP WITH HIGH STRENGTH IN COLD ROLLING MACHINE}

The present invention relates to a method for controlling the local shape of a high strength ultra-thin material in a continuous rolling mill, and more particularly, a high-strength super-pole in a continuous rolling mill for preventing a shape defect locally occurring at the center of a steel sheet during cold rolling of a high-strength ultra-thin material having a thickness of less than 0.23 mm. It relates to a local material shape control method.

In general, the shape control technique of the prior art as shown in Figures 1 to 2, the final roll consisting of the backup roll (4, 4 '), intermediate roll (3, 3'), working roll (2, 2 ') of the cold rolling mill The shape detector 5 provided on the stand exit side approximates the shape distribution of the plate width direction of the rolled steel sheet 1 close to the target shape by feed back control. The shape control approximates the shape of the rolled steel sheet 1 as a function, and the work roll (2, 2 ') bender (7) and the intermediate roll (3, 3') bender (8) and the intermediate roll (3, 3). ') A function of correcting the symmetry and compound symmetry by the combination of the fourth order curve of the roll by the shift 10 and the function of correcting the asymmetry level difference by the rolling leveling is performed.

The conventional shape control is expressed as a formula below. First, the difference in the elongation in the width direction is measured by a shape detector, and the shape is expressed by a four-dimensional approximation and used for the control. The control sequence can be expressed as follows.

First, Shape Representing Parameter Conversion will be described.

1) Approximate the shape (Y) measured by the shape meter as a quadratic function.

Y = λ _One X + λ ₂ X ² + λ ₃ X ³ + λ ₄ X ⁴

2) Convert λ _{1 to} λ ₄ into Λ ₁ to Λ ₄ .

Symmetrical Component

Λ ₂ = λ ₂ + λ ₄

Λ ₄ = 1 / 2λ ₂ + 1 / 4λ ₄

Asymmetrical Component

Λ _One = λ _One + λ ₃

Λ ₃ = 1 / √3λ _One + 1 / 3√3λ ₃

The following describes the method of estimating the shape using these measurement results.

1) Calculation of Shape Deviation (ΔΛ) and Limit Shape Deviation (ΔΛ _max )

Shape Deviation

ΔΛ ₂ = Λ ₂ -Λ ₂ Target

ΔΛ ₄ = Λ ₄ -Λ ₄ Target

Limit Shape Deviation

ΔF _{w max} : Maximum amount of work Bender manipulated to operate during Unit Control time (2 sec)

ΔF _{i max} : Maximum intermediate roll bender operation amount that can be operated for 2 seconds.

2) Calculation of search operation amount (F _ws , F _is ) and search gain

Search operation amount

F _ws = G _{w max}

F _is = G _{i max}

• Set the search gain to a value between 0 and 1.

3) Determination of Optimal Point Of Shape Correction

17 Calculation of Shape Value at Search Point

ΔΛ _2K = β ₁₁ F _wk + β ₁₂ F _ik

ΔΛ _4K = β ₂₁ F _wk + β ₂₂ F _ik

here,

Search Point, K = 1, 2, 3,... 17

17 Calculation of Assessment Function Value at Search Point

J _K = ΔΛ ₂₂ + ω _One ΔΛ ₂₂ + ω (Λ ₄ -Λ ₂ )

here,

ω _One = 1, ω ₂ = 0 (Λ ₄ ≤ Λ ₂₎

ω _One = 1, ω ₂ = 10 (Λ ₄ > Λ ₂ )

Search Point, K = 1, 2, 3,... 17

Optimizing the Optimal Point

A gujeom the J _K is minimized Sikkim operating _wk F, F _ik

This method is a very useful means to correct the change of shape to the target shape at the exit of the cold rolling mill. However, in recent years, since demands for cost reductions have increasingly demanded high strength and ultra-thin thickness, pocket wave has occurred in the width direction of steel sheet, which is difficult to control with conventional shape control means.

The cause of the high-strength ultra-thin ultra-thin material in the width direction of the steel sheet is caused by non-uniform stretching in the width direction of the steel sheet width due to non-uniform width of the thermal crown of the work roll (2, 2 ') in the high-speed section This is due to the occurrence.

The method which can minimize the width direction thermal crown phenomenon of the work rolls 2 and 2 'is most effective at the exit of the roll bite at which the temperature of a roll rises highest. However, since cooling performed at the exit of the final stand is not possible due to a problem of water dropping, coolant is sprayed at the entrance. For this reason, in the high speed section, the thermal crown of the final stand rises very high, and a pocket wave occurs in the width direction of the steel sheet, making it difficult to obtain a stable shape.

Accordingly, the present invention has been made to solve the above problems, high strength ultra-thin material in a continuous rolling machine to prevent the shape defects locally occurring in the width direction of the steel sheet during cold rolling of a high-strength ultra-ultra thin material of less than 0.23mm thick It is an object of the present invention to provide a cooling apparatus and a control method for local shape control.

1 is a schematic diagram showing a shape control system of a conventional continuous rolling mill;

2 is a schematic view showing a roll configuration and a work roll bender device of a continuous rolling mill;

3 is a schematic view showing a shape control system of a continuous mill according to a high strength super-ultra thin material local shape control method in a continuous mill according to the present invention;

Figure 4 is a flow chart showing the process of the high strength ultra-thin material local shape control method in the continuous rolling mill according to the present invention;

5 is a schematic view schematically showing a lower work roll cooling apparatus of a method of controlling a high strength ultra-thin material local shape in a continuous mill according to the present invention;

Figure 6 is a schematic diagram schematically showing the upper work roll cooling apparatus of the high strength ultra-thin material local shape control method in the continuous mill according to the present invention.

♣ Explanation of symbols for the main parts of the drawing ♣

5: Shape detector 10: Upper roll cooling device 11: Lower roll cooling device 6: Shape control part

7: work roll bender 8: middle roll bender 9: middle roll shift 24: heat exchanger

In order to achieve the above object, in the continuous mill according to the present invention, a high-strength ultra-thin material local shape control method for controlling the width direction pocket-like wave of the cold rolled super-ultra thin steel sheet in a continuous mill having a plurality of roll stands and a shape detector The method comprises the steps of: quantifying a shape defect by receiving a flatness ε _i detected by a shape detector installed under the cold rolled ultra-ultra thin material and calculating a shape deviation Δε from a computing device;

By opening and closing the valves of the upper roll cooling device and the lower roll cooling device disposed on the final stand exit side in the quantified shape defective part, the work roll is cooled to perform a roll bender so that the shape deviation Δε becomes '0'. It consists of steps.

In addition, the upper work roll cooling device has a water-closing problem because it is installed on the cold rolled ultra-thin material upper surface, and sprays cooling air as a coolant, and the lower work roll cooling device injects coolant as a coolant.

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

3 is a schematic view showing a shape control system of a continuous mill according to a method for controlling local shape of a high strength ultrathin material in a continuous mill according to the present invention, and FIG. It is a flowchart which shows a process.

Controlling the steel sheet width pocket shape generated in the high strength ultra thin material as shown in FIG. 3 in order to prevent the water shortage problem and the poor shape of the steel sheet width direction of the high strength ultrathin material at the exit of the final stand. In order to include the shape detector 5, the shape control unit 6, the upper and lower roll cooling device (10, 11) to the final stand exit. That is, the position of opening the valves of the upper roll cooling device 10 and the lower roll cooling device 11 on the final stand exit side by receiving the flatness ε _i detected by the shape detector 5 is calculated. The shape control part 6 which controls the valve opening / closing position of 10 and 11 is comprised.

As shown in FIG. 4, the shape control unit 6 controlling the roll cooling apparatuses 10 and 11 receives the flatness value ε _i detected by the shape detector 5, and thus, After calculating the difference Δε between the measured flatness ε _i and the target flatness ε _ri , the valves for the roll cooling devices 10 and 11 at the position where the flatness difference Δε occurs are opened.

The opening degree valve position of the roll cooling apparatuses 10 and 11 obtained above is opened, and it continues until the flatness difference (DELTA) (epsilon) of Formula (1) becomes "0".

5 is a schematic view showing a lower roll cooling apparatus of the high strength ultra-thin material local shape control method in a continuous rolling mill according to the present invention, Figure 6 is a top roll cooling apparatus of the high strength ultra-thin material local shape control method in a continuous mill according to the present invention. Schematic shown.

In the continuous mill according to the present invention, the roll cooling apparatuses 10 and 11 of the high strength ultra-thin material local shape control method have flatness detected by the shape detector 5 shown in Fig. 3 as shown in Figs. When ε _i is received and the shape defect is determined from the shape control section 6, the opening and closing positions of the valves 18 and 23 of the upper roll cooling device 10 and the lower roll cooling device 11 on the final stand exit side are determined. It is done.

That is, in the final stand lower roll cooling device entrance nozzle head 13, the coolant 15 is injected into the shape defective part measured by the shape detector 5, and in the exit nozzle head 14, the coolant 16 is defective in shape. It is concentrated in wealth. 6, the coolant 15 is injected into the shape defective part measured by the shape detector 5 in the same way as the final stand lower roll cooling device in the final stand upper roll cooling device. At 20, since there is a water problem, the air 21 cooled by the heat exchanger 24 is concentrated in the shape defective part. This series of steps is repeated until the shape is smooth in the shape detector 1.

Thus, the final stand lower roll cooling device 11 inlet nozzle head 13 shown in FIG. 5 based on the position of the shape defective portion in the computing device has the coolant 15 in the shape defective portion measured by the shape detector 5. ) Is injected, and the cooling water 16 is concentrated in the shape defective part in the exit nozzle head 14. 6, the coolant 15 is injected into the shape defects measured by the shape detector 1, similarly to the final stand lower roll cooling device, in the nozzle head 19 of the final stand upper roll cooling device 10 shown in FIG. 6. As a result, the cooling air 21 passing through the heat exchanger 24 at the exit nozzle head 20 is concentrated in the shape defect part.

This series of processes is continued until the flatness difference Δε of Equation 1 becomes '0'. It can be seen that the directional pocket wave has a nearly smooth shape.

The present invention calculates the shape detection value of the final stand in the shape control unit and recognizes the shape defect, and then controls the roll thermal crown by spraying cooling water and cooling air to the local shape defect in the roll cooling apparatus installed on the exit side of the final stand. By doing so, there is a great effect in reducing the steel sheet width direction pocket wave of the high strength ultra-thin material.

Claims (1)

Receiving the flatness ε i detected by the shape detector 5 installed on the lower portion of the cold rolled ultra-thin material, and calculating the shape deviation Δ ε by the following equation (1) from the shape control part 6 to quantify the shape defect. Steps; The work rolls 2 and 2 'are opened and closed by opening and closing the valves 18 and 23 of the upper work roll cooling device 10 and the lower work roll cooling device 11, which are disposed on the final stand exit side of the quantified shape defective part. And cooling the roll bender (7, 8) and shifting (9) so that the shape deviation (Δε) is set to '0'. Δε = ε _i -ε _ri --------------------- (One) (here,ε _i : Measured flatness of ultra-thin material,ε _ri : Target flatness of ultra-thin material)