KR20100069826A - A method and apparatus of controlling camber in steel sheet - Google Patents

Abstract

PURPOSE: A camber control device and a method of a steel sheet is provided to increase the control precision by performing learning control about the camber control error generating after the control application. CONSTITUTION: A method of a steel sheet comprises a camber measurement(4), a camber controller(6), and a roll-gap controller(3). The camber measurement consecutively measures an off-center of a steel sheet on the rougher outgoing of the hot rolling process. The camber controller comprises two CCD cameras and an ager speed meter. The camber controller extracts a representative camber value. The camber controller revises the camber control error by learning resistivity correction factor. The camber controller calculates the level control amount by processing the off-center data measured at the camber measurement. The roll gap controller controls the location of roll-gap based on the level control amount calculated in the camber controller.

Description

A Method and Apparatus of Controlling Camber in Steel Sheet

The present invention relates to a method and apparatus for automatically controlling a camber of a steel sheet generated by left and right asymmetrical rolling conditions of a rolling mill in a hot rolling process. A camber control method for performing automatic level setting control on a subsequent camber control error and improving control accuracy through learning control, and a camber measurement and control device configured to be suitable for executing the method.

In general, the camber of the steel sheet mainly generated in the rough rolling process of hot rolling is an important factor that affects the plateability and the quality of the steel sheet. Excessive camber may cause equipment accidents such as pinching and bumping of the steel plate in equipment such as side guides, and it may cause meandering in finishing rolling by camber in rough rolling, resulting in a problem of sheet flow of the steel sheet. Cause. In addition, the camber generated at the tip of the steel sheet generates a telescope shape problem during the coiling operation in the coil winding machine, thereby causing quality problems such as a decrease in the error rate and frictional scratches in the post process.

In order to control the camber, the control method that has been used most commonly in the industry is a so-called load that controls the level, that is, the left and right deviation of the roll gap so as to reduce the roll gap with respect to the larger load by receiving a rolling load signal. Car control system (Japanese Patent Laid-Open No. 10-244307, Japanese Patent Laid-Open No. 11-188415, Japanese Patent Laid-Open No. 2006-150414).

In this method, however, wedges, i.e., left and right thickness variations, exist in the steel sheet, and when the difference in load occurs, the gap is reduced for the larger load. .

On the other hand, Japanese Patent Publications 2002-120005 and 2002-210513 propose a method for calibrating cambers using side guides, but the role of side guides is effective in suppressing camber generation by strictly managing guide gaps. There is a problem in that the practical application is limited because it requires a lot of equipment to actively control the camber.

Accordingly, in order to solve the above problems, the present inventor proposes a method and apparatus for installing a camber measuring device on the rough rolling side to measure the camber value directly and automatically control the level to reduce the generated camber.

An object of the present invention relates to a method and an apparatus capable of automatically controlling a level so that a camber does not occur on the rough rolling exit side of a hot rolling process. In particular, a camber measuring instrument is installed on the rough rolling exit side to measure and generate a camber. It is an object of the present invention to provide a method and apparatus for operating a rolling mill cylinder by automatically calculating the roll gap amount for removing a camber.

A feature of the present invention is to extract the representative camber value from the off-center value measured by the camber measuring instrument, and to calculate the level control amount using a camber prediction model to zero the top camber value among them, and control A camber control method for improving control accuracy by performing learning control on a camber control error occurring after application and an automatic control device for automatically performing such a process can be characterized. (* off-center: When the bar enters the rolling mill, the progress center line of the bar does not match the center line of the rolling mill)

In order to achieve the above object, the camber control device of the steel sheet of the present invention,

A camber measuring device for continuously measuring the off-center of the steel sheet at the rough rolling exit of the hot rolling process, a camber controller for calculating the level control amount by processing the off-center data measured by the camber measuring device, and calculated by the camber controller It is characterized by comprising a roll gap control device for controlling the position of the roll gap on the basis of the level control amount.

The camber measuring device may include two CCD cameras and one laser speedometer.

The camber measuring device may extract a representative camber value, calculate a level control amount, and correct the camber control error by learning a correction coefficient.

Moreover, the camber control method of the steel plate of this invention,

Directly measuring off-center data of the entire steel sheet at the rough rolling exit of the hot rolling process, and processing the measured off-center data in a camber controller to extract a representative camber value; Calculating the level control amount for the next plate by applying the influence coefficient of the camber to the roll gap, and providing the calculated level control amount as a position reference value of the roll gap control device to change the position of the roll gap. do.

The method may further include correcting the camber control error by performing learning control on the camber control error occurring after the control is applied after the roll gap change step.

In addition, the off-center data measuring step is characterized by measuring by a CCD camera and a laser speed meter,

The extracting of the representative camber value may include filtering the raw off-center data to remove noise components, and classifying the filtered data into a top, middle, and tail unit. Curve fitting of the classified data to obtain a warpage shape of the entire plate; obtaining camber values for each part based on the curve-fitted data; and camber control from camber values for the respective parts. Characterized in that the step consists of obtaining a representative camber value for.

Further, in the camber control method of the steel sheet, the data classification, the first 20% and the last 20% in the total data for the stand alone is classified as the top (Tail) and tail (Tail) data, the remaining 60% in the middle ( Middle) to each of the data characterized in that the classification,

In the step of calculating the camber value for each part, the middle camber value is the average value of the middle data, the top camber value is the absolute value of the curve-fitting top off-center minus the middle camber, Some camber values are calculated for curve-fitted tail portion cambers in the same way as for top cambers.

The representative chamber value may be an average value of camber values of the top portion and the tail portion,

In the controlling of the level control amount, the camber prediction model is derived, the influence coefficient for the roll gap is obtained from the camber prediction model, and the level control amount for the next plate is calculated using the influence coefficient and the representative camber value for the roll gap. Characterized in that.

In addition, the camber prediction model is derived from a finite element simulation result of various operating conditions and roll gap conditions, and is characterized by the following equation (2).

(Eq. 2)

은 각 스탠드 출측에서 패스 스케쥴, 폭, 롤 갭에 따라서 다르게 계산되며, C는 예측 캠버값, W는 강판의 폭, X는 롤 갭으로부터의 거리, S는 레벨, 즉 좌.우 롤갭의 차이를 나타낸다.* Parameter in the above formula

Is calculated differently according to the pass schedule, width, and roll gap at each stand exit, where C is the predicted camber value, W is the width of the steel plate, X is the distance from the roll gap, S is the level, i.e. the difference between the left and right roll gaps. Indicates.

In addition, the coefficient of influence on the roll gap is characterized by the following equation 3.

(Equation 3)

* The symbol used in the above formula is the same as the above formula (2).

In addition, the level control amount for the next plate (k) is characterized by the following equation (4).

(Equation 4)

은 이전 판 (k-1 번째)에 대한 대표 캠버 값이고, 다른 기호는 상기 식 2와 동일하다.* In the formula above

Is the representative camber value for the previous plate (k-1 th), and the other symbols are the same as in Equation 2 above.

)를 적용하는 것을 특징으로 한다.In addition, the step of correcting the camber control error is a correction coefficient (Equation 5)

It is characterized by applying).

(Equation 5)

In the above formula, the coefficient a has a value between zero and one and is related to the speed of learning, and the other symbols are the same as in the above equations 2 and 4.

In the present invention, since the camber is directly measured by using a CCD camera and a laser speedometer, the camber measurement accuracy is high and the camber control is performed with high accuracy. In addition, it is possible to actively control the camber generated by controlling the level of the roll gap instead of controlling the gap of the side guides. The biggest effect of the present invention is that the operator's workload is measured by measuring the camber with a camber measurer and automatically controlling the level using a computer, instead of the conventional way in which the operators view the ITV camera screen and control the camber manually. In addition to reducing the number of steps, the camber control is more accurate than the operator's empirical method.

Hereinafter, the present invention will be described with reference to the accompanying drawings. 1 is a schematic diagram of an automatic camber control device. 2 is a schematic diagram of a camber measuring instrument. 3 is a graph illustrating a process of extracting a representative camber value. 4 is camber vs. Level simulation graph.

5 is a graph showing the application result of the automatic camber control.

When the steel sheet, which is the rolled material 5 in FIG. 1, passes through the camber measuring unit 4 after rolling in the rolling mill, the camber measuring unit 4 uses two CCD cameras 7 and one laser speedometer ( 8) measure the off-center of the steel plate continuously. After the steel sheet has completely exited the camber measuring instrument 4, the camber measuring instrument 4 transmits off-center data for the entire steel sheet to the automatic camber controller 6 through communication.

The camber controller 6 extracts the camber values of the top, middle, and tail parts through the camber value extraction process as shown in FIG. 3 with respect to off-center data corresponding to the entire length of the plate. do.

Extracting the camber value is as follows. The first step removes noise components by filtering on raw off-center data. In the present invention, the moving component is first applied to remove the noise component.

The second step is to divide the filtered data into Top, Millde, and Tail sections. In the method of dividing the top part and the tail part, for the stand alone , the first 20% and the last 20% are classified as the top and tail data and the remaining 60% as the middle data. On the other hand, for the tandem stand , data corresponding to the distance between the two stands in the total data is classified into the top and tail portions, and other data are classified into the middle portion data.

The third step is to perform curve fitting on each data part. This is to obtain the overall flexure of the plate for each data filtered first. In general, curve fitting is performed as a first-order function for middle off-center and as a second function for top and tail data.

The fourth step is to find camber values for each part based on the curve-fitted data. First, the average of middle data is obtained and defined as middle camber. The middle camber generally indicates which way the steel sheet passes in the center of the roller table. The top camber takes the absolute value of the curve-fitted top off-center minus the middle camber and defines the largest of them as the top camber. In other words,

(1)

(One)

The tail camber is calculated using the same method as the top camber for the fitted tail camber.

After the camber value for each part of the steel sheet is obtained, a representative camber value for camber control is obtained. Although the level can be changed before the plate is inserted into the rolling mill due to the characteristics of the rough rolling equipment, it is necessary to extract the representative camber value to apply the camber control since the level value cannot be changed once the steel sheet is inserted into the rolling mill. The representative camber value is defined as the average value of the camber values of the top part and the tail part. Therefore, if the top camber and the tail camber have different directions, the level control is performed in the direction of reducing the large camber value.

Once the representative camber value is obtained, the level control amount for the next plate to remove this representative camber value is calculated. The level control amount is calculated based on the camber prediction model as follows.

(2)

(2)

은 각 스탠드 출측에서 패스 스케 쥴, 폭, 롤 갭에 따라서 다르게 계산이 되며 C는 예측 캠버값, W는 강판의 폭, X는 롤 갭으로부터의 거리, 그리고 S는 레벨, 즉 좌.우 롤갭 차이, 를 나타낸다. 예를 들어, 입측 slab 두께 200mm 의 STS430 소재에 대한 R4 스탠드에서 각각의 파라미터 값은 다음과 같이 주어진다.Parameter in the above formula

Is calculated differently according to the pass schedule, width, and roll gap at each stand exit, where C is the predicted camber value, W is the width of the steel plate, X is the distance from the roll gap, and S is the level, i.e. the left and right roll gap difference. , Is indicated. For example, each parameter value in an R4 stand for an STS430 material with a 200 mm thick side slab is given by:

Equation (2) is derived from the finite elementary method simulation results for various operating conditions and roll gap conditions as shown in FIG.

By integrating the equation (2), the inverse of the influence coefficient of the camber on the roll gap can be obtained.

(3)

(3)

Using the above equation and the representative camber value, the level control amount for the next plate (kth) is calculated as follows.

(4)

(4)

은 이전 판 (k-1 번째)에 대한 대표 캠버 값을 나타내고 음의 부호는 캠버를 줄이기 위한 방향을 나타낸다. 이상적인 경우 위의 레벨 값을 적용하면 캠버가 영으로 되어야 한다. 그러나, 실제적으로는 모델 (3)에는 항상 모델 에러가 존재하며 또한 프로세스에 외란이 존재하므로 식(4)에서와 같이 보정 계수

를 곱하여 레벨 값을 적용한다.From above

Indicates a representative camber value for the previous plate (k-1 th) and a negative sign indicates the direction for reducing the camber. Ideally, the camber should be zero with the above level values. In practice, however, there is always a model error in model (3) and a disturbance in the process, so the correction factor is as shown in equation (4).

Apply the level value by multiplying by.

This correction factor corrects camber control error caused by model error and disturbance. It is learned by the following method.

(5)

(5)

Here, the coefficient a has a value between zero and one and relates to the speed of learning.

The level control amount calculated in Equation (4) is provided as a position reference value of the roll gap controller as shown in FIG. 1 to change the position of the roll gap.

In FIG. 4, the effects of the present invention are described through the automatic level control application result. In this embodiment, the camber control is performed by automatically measuring the camber in the R4 camber measuring instrument to control the level of the R3 stand. In this example, the camber control is constrained so that the level control is applied when the absolute value of the camber is larger than the specification (set here to 15 mm) and when the camber control occurs more than two times in succession. In the figure, blue represents measured camber values and pink represents level control values. This embodiment shows that appropriate level control is performed when the camber value exceeds the spec twice or more so that the camber value is automatically managed within the specification range.

1 is a schematic diagram of an automatic camber control device.

2 is a schematic diagram of a camber measuring instrument.

3 is a graph illustrating a process of extracting a representative camber value.

4 is camber vs. Level simulation graph.

5 is a graph showing the application result of the automatic camber control.

♠ Explanation of symbols for main part of drawing?

1: work roll 2: backup roll 3: roll gap control device

4: Camber meter 5: Rolled material 6: Camber controller

7: CCD camera 8: laser speedometer

Claims (15)

A camber measuring instrument that continuously measures off-center of the steel sheet at the rough rolling exit side of the hot rolling process, A camber controller which calculates a level control amount by processing the off-center data measured by the camber measuring instrument; And a roll gap control device for controlling the position of the roll gap based on the level control amount calculated by the camber controller. The method of claim 1, The camber measuring device is a camber control device of a steel sheet, characterized in that it consists of two CCD cameras and one aceometer. The method of claim 1, The camber measuring device extracts a representative camber value, calculates a level control amount, and corrects a camber control error by learning a correction coefficient. Directly measuring off-center data for the entire steel sheet at the rough rolling exit of the hot rolling process; Extracting representative camber values by processing the measured off-center data in a camber controller; Calculating the level control amount for the next plate by applying the representative chamber value to the influence coefficient of the camber on the roll gap; And providing the calculated level control amount as a position reference value of the roll gap control device to change the position of the roll gap. The method of claim 4, wherein And adjusting the camber control error by performing a learning control on the camber control error occurring after the control is applied after the roll gap change step. The method according to claim 4 or 5, The off-center data measuring step is a camber control method of a steel sheet, characterized in that measured by a CCD camera and a laser speed meter. The method according to claim 4 or 5, The extracting of the representative camber value may include filtering the raw off-center data to remove noise components; Classifying the filtered data into a top, middle, and tail section; Curve fitting each of the classified data to obtain a warpage shape of the entire plate; Obtaining a camber value for each part based on the curve-fitted data; And a representative camber value for camber control from the camber values for the respective parts. The method of claim 7, wherein In the data classification, the first 20% and the last 20% of the stand alone are classified into the top and tail portions data, and the remaining 60% is classified into the middle portions data. A camber control method for steel sheet characterized by the above-mentioned. The method of claim 7, wherein In calculating the camber value for each part, the middle camber value is an average of the middle data. The top camber value is the absolute value of the curve-fitted top off-center minus the middle camber, Tail part camber value is calculated for the curve-fitted tail part camber by the same method as the Top camber. The method of claim 7, wherein The representative chamber value is an average value of camber values of a top part and a tail part. The method of claim 4, wherein The step of controlling the level control amount, A camber control method for a steel sheet characterized by deriving a camber prediction model, obtaining an influence coefficient for the roll gap from the camber prediction model, and calculating a level control amount for the next plate using the influence coefficient for the roll gap and the representative camber value. The method of claim 11, The camber prediction model is derived from the results of finite element simulation simulations for various operating conditions and roll gap conditions, and the camber control method of a steel sheet according to the following Equation 2. (Eq. 2)

* Parameter in the above formula

Is calculated differently according to the pass schedule, width, and roll gap at each stand exit, where C is the predicted camber value, W is the width of the steel plate, X is the distance from the roll gap, S is the level, i.e. the difference between the left and right roll gaps. Indicates. The method of claim 11, The influence coefficient for the roll gap is the camber control method of the steel sheet, characterized in that the following equation 3. (Equation 3)

* The symbol used in the above formula is the same as the above formula (2). The method of claim 11, The level control amount for the next plate (k) is the camber control method of the steel sheet, characterized in that the following equation 4. (Equation 4)

* In the formula above

Is the representative camber value for the previous plate (k-1 th), and the other symbols are the same as in Equation 2 above. The method of claim 5, The step of correcting the camber control error is a correction factor (Equation 5)

) Is applied to the camber control method of the steel sheet. (Equation 5)

In the above formula, the coefficient a has a value between zero and one and is related to the speed of learning, and the other symbols are the same as in the above equations 2 and 4.

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