KR100799709B1 - Cold rolling strip profile control method at tandem cold rolling mill - Google Patents

Abstract

An object of the present invention is to provide a method for controlling a rolled steel profile in continuous rolling in continuous rolling, which prevents failure of build-up due to thickness variation of the rolled steel sheet.

According to the present invention, in the method of controlling the profile of the rolled steel sheet 3 which is rolled through a plurality of rolling mills 1a to 1e arranged in a row, the next rolling in preparation for entering into the plurality of rolling mills 1a to 1e. Measuring and inputting the width wedge of the steel sheet (3), receiving a profile of the next rolled steel sheet (3) from the upper calculator (7), and the rolling mill (1a) according to the size of the measured wedge To calculate and control the roll gap of the work roll 11 of ˜1e), the position of the intermediate roll 12 which rotates in contact with the work roll 11, and the bender force Fw applied to the work roll 11 Provided is a method for controlling a profile of a rolled steel sheet comprising a step.

Description

Cold rolling strip profile control method at tandem cold rolling mill

1 is a conceptual view of profile control of a rolled steel sheet in a continuous rolling mill according to the prior art,

2 is a front view showing the roll level of the six-stage rolling mill shown in FIG.

3 is a schematic view showing a profile control process of a rolled steel sheet according to the prior art,

4 is a conceptual diagram of a method for controlling a rolled steel sheet profile in continuous rolling according to an embodiment of the present invention;

5 is a front view showing the roll level of the six-stage rolling mill shown in FIG.

6 is a graph showing the shape of the steel sheet according to the position of the intermediate roll,

7 is a simulation graph by the method of controlling the rolling steel sheet profile in continuous rolling according to an embodiment of the present invention.

       ♠ Explanation of symbols on the main parts of the drawing ♠

  1a ~ 1e: stand 3: rolled steel sheet

  7: Top Calculator 11: Work Roll                 

  12: middle roll 13: reinforcement roll

15: position of the intermediate roll 100: rolling mill

The present invention relates to a method for controlling a profile of a rolled steel sheet, and in particular, to measure the profile of the rolled steel sheet before the rolled steel sheet enters the continuous rolling mill, and to measure the roll gap of the rolling mill, the position of the roll and the bender force by using the measured information. The present invention relates to a method for controlling a rolled steel sheet in continuous rolling by reducing the thickness deviation of the rolled steel sheet to prevent defects.

In the profile (thickness in the width direction) of the rolled steel sheet, when a thickness deviation in the width direction (hereinafter referred to as a 'wedge') occurs, the coiled steel sheet is wound on the coiled steel sheet when the rolled steel sheet is wound with the coiled steel sheet. Build-up phenomenon occurs. These buildup failures include the Center Build-up in the widthwise center of the rolled steel sheet and the Edge build-up at the edge of the rolled steel sheet. have.

The cause of the build-up is firstly caused by the high spot of the hot rolled coil, which is a cold rolled material, that is, the thickness deviation in the width direction of the hot rolled coil described above, and secondly, the shape control stage of the cold mill. Occurs when the setting of the work roll and the intermediate roll bender force, the intermediate roll position, and the flow rate of the rolling oil is incorrect.                         

Conventionally, in order to control the shape of the rolled steel sheet, the table data is set by initial setting information, that is, the steel type, width, and thickness, and the rolled steel sheet inputted from the supervisory control computer (SCC) without measuring the shape of the incoming rolled steel sheet. The roll gap and the bender force were controlled only by the steel grade, width, and thickness of the steel sheet. Occasionally, the operator arbitrarily controlled roll gaps and bender forces when wedges were formed at stands 1 and 2 of the plurality of stands. Due to the work of the worker's personal sense, a thickness deviation occurs in the rolled steel sheet rolled in the continuous rolling mill, which results in poor build-up during winding.

1 is a conceptual view of a profile control of a rolled steel sheet in a continuous rolling mill according to the prior art, Figure 2 is a front view showing the roll level of the six-stage rolling mill shown in Figure 1 and its operation diagram, Figure 3 is a conventional Schematic diagram showing the profile control process of the rolled steel sheet according to the technology.

As shown in FIG. 1, information of the rolled steel sheet 3 entering from a supervisory control computer (SCC) 7 is input, and from these pieces of information, a roll gap of five stands 1a to 1e and Set vendor power. In this way, the set roll gap and the vendor force are obtained from the previously operated work data (table data) and set.

On the other hand, as shown in Figure 2, each stand is a six-stage stand (1a ~ 1e) having six rolls (11, 12, 13), each roll (11, 12, 13) as shown in FIG. Rolling control is performed by the set bender forces Fw and Fi and the roll gap. On the other hand, when the rolled steel sheet 3 on which the wedge is formed is rolled while passing between two parallel work rolls 11, the rolled steel sheet 3 meanders and plate breakage occurs.

In order to prevent this, as shown in FIG. 3, the worker works as much as possible (about 20 mm) the position 15 of the middle roll 12 of the stands 1a to 1e, and maximizes the bender forces Fw and Fi. In this rolling condition, the rolling force applied to one end portion of the width of the rolled steel sheet 3 becomes large, and edge build-up occurs.

Here, the position of the intermediate roll 12 is an interval between the end of the intermediate roll 12 and the wedge of the rolled steel sheet 3, and the case where there is no such interval is a zero point, and is shown in FIG. The intermediate roll 12 is moved to the left direction, i.e., the edge of the rolled steel sheet 3, and the gap generated is (+), and the intermediate roll 12 is moved to the right direction, that is, the middle part of the rolled steel sheet 3 The interval generated by this is (-). Conventionally, the operation of setting the position of the intermediate roll 12 within 20 mm is common.

On the other hand, the rolling method proposed in Japanese Patent Laid-Open Publication No. 06-015309 (name of the invention; multiple rolling mill for sheet rolling) was proposed mainly for edge-drop control, but the material is low crown in continuous rolling of soft materials. Edge build-up occurs in materials with large or wedges.

The present invention is provided to solve the problems of the prior art as described above, the roll gap of the rolling mill, the position and the bender of the rolling mill by measuring the profile of the rolled steel sheet prior to entering the rolling mill and using the measured information By controlling the force, an object of the present invention is to provide a method of controlling a rolled steel sheet in continuous rolling to reduce the thickness deviation of the rolled steel sheet to prevent build-up.

According to the present invention for achieving the object as described above, in the profile control method of the rolled steel sheet rolled through a plurality of rolling mills arranged in a line, the width of the next rolled steel sheet being prepared to enter the plurality of rolling mills Measuring and receiving a wedge, receiving a profile of the next rolled steel sheet from an upper calculator, a work roll roll gap of the rolling mill according to the measured wedge size, and an intermediate roll rotating in contact with the work roll. Provided is a profile control method for a rolled steel sheet including calculating and controlling a position and a bender force applied to the work roll.

In the following, with reference to the accompanying drawings, preferred embodiments of a method for controlling a rolled steel sheet profile in continuous rolling according to the present invention will be described in detail.

4 is a conceptual diagram of a method for controlling a rolled steel sheet profile in continuous rolling according to an embodiment of the present invention, FIG. 5 is a front view showing a roll level of the six-stage rolling mill shown in FIG. 4, and FIG. 6 is an intermediate view. It is a graph which shows the shape of the steel plate with a roll position.

As shown in FIG. 4, in front of the rolling mill 100 in which the five stands 1a to 1e are arranged in a line, a profile measuring unit 20 for recognizing the profile of the rolling steel sheet 3 to be advanced is installed. Then, by analyzing the information on the rolled steel sheet 3 measured by the profile measuring unit 20 and the information of the rolled steel sheet 3 input from the upper calculator 7 to actively change the roll level (Figure 2) 12) The edge buildup is suppressed as much as possible by performing the rolling operation with the maximum position (about 200 mm) and the bender force small.

Roll gap control and shape control stage setting control are required to control the rolled steel profile in such continuous rolling.

The roll gap control recognizes the profile of the rolled steel sheet (hereinafter referred to as 'entrance material') entering the rolling mill 100 during continuous cold rolling from the profile measuring unit 20, and the rolled steel sheet currently rolling Calculate the wedge amount (We) of the 'work material') and the next rolled steel sheet (hereinafter referred to as the 'work material') as shown in Equation 1.

Where n is the current work piece, n + 1 is the next work piece, We is the wedge amount, Hd is the rolled sheet thickness on the drive side (D / S), and Hw is the work side (W / S thickness of the rolled steel sheet on the work side.

In addition, the roll gap setting values of the drive side D / S and the work side W / S of the work roll 11 currently being rolled are calculated as in Equation (2).

Here, SLn is the gap difference of the work roll currently being rolled, Sdn is the roll gap of the drive side, and SWn is the roll gap of the work side.                     

As shown in FIG. 5, the gap is set and controlled by calculating the reset values of the driving and working roll gaps in the wedge amount of the current work material and the wedge amount of the next work material as shown in Equation 3.

Where Sd (n + 1) is the roll gap for rolling the next work piece, n is the current work piece, n + 1 is the next work piece, and a is a constant. The roll gap of the work roll is controlled by the roll gap calculated as in Equation (3).

On the other hand, the shape control stage setting control method will be described in detail below.

The position (FL) 15 of the intermediate roll 12 shown in Figure 2 is calculated and set to the optimum position, the crown (Ch) of the rolled steel sheet 3 is calculated as shown in Equation 4 below.

Where P is the rolling load (ton), Fw is the working roll bender force, FI is the intermediate roll bender force, FL is the intermediate roll position, Ch _i-1 is the entrance crown, and ε is the reduction ratio (Δh) / h), Thi is the rolling exit thickness, i is the stand number, a, b, c, d, e, f, g, h are constants, are shown in Table 1 below. And, the middle roll optimum position (FL) is set according to the steel grade, thickness, width as shown in Figure 6, the maximum position in the present invention is 200mm, it is set relatively larger than the conventional middle roll position 20mm.

As shown in FIG. 6, the roll-up steel sheet 3 in which build-up does not occur is shown as a build-up generated while passing through the stands 1a to 1e. Buildup was formed at the edge of the rolled steel sheet 3 even when the position 15 was 20 mm, but in one embodiment of the present invention, no buildup occurred even when the intermediate roll position was 200 mm. As a result, even if the intermediate roll position 15 is moved to a width larger than the intermediate roll position change in the conventional rolling mill, the edge buildup of the rolled steel sheet does not occur.

Next, each stand entry / exit crown ratio (Δλ) is calculated by the following equation (5).

A condition where the stand exit shape is flat is CL (minimum crown) < Δλ < CU (maximum crown), and each stand exit crown (Chi) is calculated under an optimum condition where Δλ = 0.

From the equation (4), the bender force of the intermediate stand is set to 0 (zero), and the optimum work roll bender force Fw at each stand is calculated as in the following equation (6).

When the work roll bender force Fw reaches about 80% of the maximum value, the intermediate roll bender force Fi is calculated and increased as shown in Equation 7 below, thereby setting the optimum intermediate roll bender force.

In this way, the work roll and the reinforcement roll are controlled by the calculated roll gap and the bender force and the set intermediate roll position to roll the rolled steel sheet 3.

As described in detail above, the method of controlling the rolled steel profile in the continuous rolling of the present invention measures the profile of the rolled steel sheet entering the continuous rolling mill and provides a roll gap, an intermediate roll position and a bender force to the wedge of the rolled steel sheet. There is an advantage in that it is possible to prevent the failure and failure of the build-up caused by the failure.

At present, the method of controlling the rolled steel profile in the continuous rolling of the present invention has been applied in the cold rolling of Pohang Works in Korea. As a result, the edge buildup occurrence rate of 0.33% is reduced to almost 0% edge buildup occurrence rate before application.

Although the technical idea of the method for controlling a rolled steel sheet profile in continuous rolling of the present invention has been described above with reference to the accompanying drawings, this is by way of example and not by way of limitation. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (1)

In the profile control method of the rolled steel sheet rolled through a plurality of rolling mills arranged in a line, Receiving and measuring the width wedge of the next rolled steel sheet being prepared to enter the plurality of rolling mills; Receiving a profile of the next rolled steel sheet from a higher calculator; And calculating and controlling a work roll roll gap of the rolling mill according to the measured wedge size, a position of an intermediate roll rotating in contact with the work roll, and a bender force applied to the work roll. Profile control method of rolled steel sheet.

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