KR20030048932A - Strip thickness control system and method using filtered rolling force & skid mark thickness variation - Google Patents

Abstract

PURPOSE: A method for controlling thickness of strip by filtering rolling force measuring signals and estimating skid mark thickness deviation is provided to control thickness deviation of strip caused by skid mark and minimize thickness deviation of strip according to roll eccentricity. CONSTITUTION: In a strip thickness control apparatus(107) of continuous rolling mill for performing auto gap control (AGC) using strip thickness deviation, the apparatus comprises an AGC gain setting part(409) for calculating roll eccentricity frequency by receiving various parameters for thickness deviation estimation, designing filter for extracting skid mark thickness deviation, calculating skid mark thickness deviation and setting AGC gain through AGC gain learning using table representing relation between proper AGC gains and skid mark thickness deviation; a rolling force filtering part(413) for calculating a rolling force in which rolling force components having frequency of roll eccentricity frequency or more are removed from rolling force by roll eccentricity by receiving various parameters for estimating thickness deviation; and thickness control part(411) for performing thickness control by minimizing thickness deviation according to roll eccentricity after receiving data from the rolling force filtering part and AGC gain setting part.

Description

Thickness control system and method using filtered rolling force & skid mark thickness variation}

The present invention relates to a thickness control method through rolling load filtering and skid mark thickness deviation prediction. More specifically, the automatic plate thickness control (AGC) is obtained by obtaining a plate thickness deviation from a measurement signal of a rolling load and a pressing position. In the rolling control of the continuous rolling mill, the thickness variation caused by the skid mark is controlled, and the thickness control method through filtering the rolling load measurement signal and predicting the skid mark thickness variation so as to minimize the thickness variation due to the roll eccentricity. It is about.

1 is a configuration diagram of a typical rolling mill thickness control device, Figure 2 is a modeling diagram for the thickness control device shown in FIG.

In the conventional plate thickness control method according to the present invention, as shown in Figs. 1 and 2, the rolling load is detected by the load cell 105 and the pressed position is detected by the position detector 106, and the exit plate thickness calculation formula is performed. After changing the [Equation 1] below [Equation 2] to [Equation 2] to obtain the plate thickness deviation, the pressure reduction position was adjusted in the direction to eliminate this deviation to obtain a uniform plate thickness. Such a conventional control method is generally widely used in a gauge meter method.

here, Is the outboard plate deviation, M is the whole number, Kg is the AGC gain, (= F ₀ -F) is the rolling load variation (F ₀ , F: AGC starting time and current rolling load), (= S ₀ -S) is the pressing position moving amount S ₀ , S: AGC starting time and the current pressing position.

Factors causing plate thickness variation include side plate thickness fluctuations, skid marks, and thermal crowns, all of which are detected as rolling load fluctuations, and the exit plate thickness is obtained by Equation 1 above.

However, there are load fluctuations generated from the rolling mill itself as well as load fluctuations due to plate thickness fluctuation factors. For example, if the rolling mill is rotated while the upper and lower rolls are in contact, a constant load is not detected. This occurs because when the roll is rotated, the roll spacing is changed by a roll or a key groove, etc., which are not round. This roll gap variation is not detected by the down position detector, but only appears in the rolling load, resulting in malfunction of the AGC.

For example, when the roll gap becomes narrow due to the roll eccentricity, the plate thickness becomes thin, and the rolling load increases. At this time, since the AGC predicts the thickness according to [Equation 2], it is determined that the rolling load increases and the rolling position does not change. It malfunctions to make it thinner to increase the plate thickness variation. In addition, when AGC gain Kg is large from [Equation 2], the thickness variation with respect to the roll eccentricity is large, and when it is small, it can be predicted that the exit thickness variation according to the entrance thickness variation by a skid mark etc. becomes large.

In the rolling mill employing the AGC by the gauge meter method using the rolling load, a problem of AGC malfunction due to roll eccentricity occurs. This problem can be ameliorated by efforts to eliminate roll eccentricity through sophisticated roll processing and mechanical assembly, but it is expensive and time consuming. In addition, there is a method of controlling the roll eccentricity by recognizing the form of the rolling load variation caused by the roll eccentricity by the Fourier analysis method as a countermeasure of the roll eccentricity, and operating the pressing position in the direction of removing the roll eccentricity by the hydraulic pressing device. . This method must be able to accurately and quickly extract the rolling load fluctuation due to the roll eccentricity, and requires a responsive pressing device with good response. And, if the roll eccentric control is not properly performed in the front end stand, adversely affects the roll eccentric control of the next stand. This makes the roll eccentric shape of the shear stand unrecognizable, resulting in malfunction of the pressing device with good response.

Further, according to Japanese Patent Application Publication No. 59-209413, the dynamic characteristics of the roll eccentricity and the rolling control system judged by using the load fluctuation range as the roll rotates in the kis roll state after the roll replacement or before rolling reforming. The method of setting AGC gain (Kg) for minimizing the malfunction of AGC for roll eccentricity is presented by using the relation of the pressing position with respect to the roll eccentricity using a model equation.

However, this method has a problem of requiring a dynamic characteristic model of the accurate rolling control system.

An object of the present invention for solving the problems of the prior art as described above is to obtain a skid mark in the rolling control of a continuous rolling mill which performs automatic plate thickness control (AGC) by determining plate thickness deviation from a measurement signal of a rolling load and a pressing position. It is to provide a thickness control method by filtering the rolling load measurement signal and predicting the skid mark thickness deviation in order to control the thickness variation caused and minimize the thickness variation due to the roll eccentricity.

1 is a configuration diagram of a typical rolling mill thickness control device,

FIG. 2 is a modeling diagram for the thickness control device shown in FIG. 1;

3 is a flowchart illustrating a process of obtaining a skid mark thickness deviation;

4 is a configuration diagram of a continuous rolling mill to which the thickness control method according to an embodiment of the present invention is applied.

※ Explanation of code about main part of drawing ※

101: job roll 102: backup roll

103: rolled material 104: roll gap adjusting device

105: load cell 106: roll gap measuring instrument

107: thickness controller 108: roll gap adjustment device driver

409 AGC gain setting device 410: mill initial setting computer

411 thickness gauge 412 speed meter

413: rolling load filtering device

In order to achieve the above object, according to the present invention, in the thickness control apparatus of the continuous rolling mill to perform the automatic plate thickness control (AGC) by using the plate thickness deviation, the roll eccentric frequency by receiving various parameters for the thickness deviation prediction AGC gain that sets AGC gain through calculation, filter design for extraction of skid mark thickness deviation, calculation of skid mark thickness deviation, and AGC gain learning using skid mark thickness deviation and table expressing relationship between appropriate AGC gain Setting unit; A rolling load filtering unit which receives various parameters for predicting thickness deviation and calculates a rolling load from which a rolling load component having a frequency equal to or greater than a roll eccentric frequency is removed from the rolling load due to the roll eccentricity; And a thickness controller configured to receive thickness data from the rolling load filtering unit and the AGC gain setting unit to minimize thickness variation due to roll eccentricity, and to perform thickness control. to provide.

In addition, in the thickness control method of the continuous rolling mill to perform the automatic plate thickness control (AGC) using the plate thickness deviation, to control the thickness deviation caused by the skid mark, the steel grade, the furnace ash time, the furnace extraction temperature, the plate Setting AGC gains in consideration of widths, rolling mill entry and exit plate thicknesses, and then optimizing AGC gains by learning using skid mark thickness deviations; Removing a rolling load component having a frequency greater than or equal to the roll eccentric frequency from the rolling load by using the optimized value to minimize thickness variation due to roll eccentricity; And minimizing thickness variation due to roll eccentricity using the value from which the rolling load component is removed. There is provided a thickness control method of a continuous rolling mill comprising a.

Hereinafter, a thickness control method through rolling load filtering and skid mark thickness deviation prediction according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The present invention provides a rolling load due to roll eccentricity to minimize thickness variation due to roll eccentricity and to control thickness variation due to skid marks without requiring equipment modification, a roll eccentric control device, and a dynamic model of a rolling control system. The method provides a method of controlling thickness by appropriately setting the gain of AGC in consideration of steel grade, ashing time of furnace, extraction temperature, plate width, and plate thickness of rolling mill.

That is, the present invention sets AGC gain (Kg) per stand in consideration of steel grade, furnace time, furnace extraction temperature, plate width, rolling mill entry and exit plate thickness, and roll eccentric frequency from roll rotation speed and roll diameter. Is a thickness control method using a rolling load by designing a filter that removes a frequency component above the roll eccentric frequency, removing the rolling load component due to the roll eccentricity included in the measured rolling load by using the filter. Where Kg is AGC gain.

The AGC gain setting of the present invention will be described in detail as follows.

Stands using tables expressing the relationship between the degree of skid marks and rolling properties, namely steel grade, furnace ash time, furnace extraction temperature, plate width, rolling mill entry and exit plate thickness, and the appropriate AGC gain Set star AGC gain. In this case, the table is constructed through analysis of operation characteristics in the absence of roll eccentricity. In order to optimize the AGC gain, the skid mark thickness deviation is calculated from the performance thickness, and the AGC gain is learned as shown in Equation 3 below using the thickness deviation.

Here, Kg _new is AGC gain before learning, Kg _old is AGC gain after learning, alpha is learning gain, Is the skid mark thickness deviation.

3 is a flowchart illustrating a process of obtaining a skid mark thickness deviation.

First, in step S301, the roll eccentric frequency for each stand is calculated, and in step S302, the performance thickness is filtered to remove the thickness component having a frequency that is greater than or equal to the minimum among the roll eccentric frequencies for each stand, and then in steps S303 and S304, The maximum minimum thickness is detected within the mark period. In step S305, the difference between the maximum minimum thicknesses is obtained and this value is used as the skid mark thickness deviation.

4 is a configuration diagram of a continuous rolling mill to which the thickness control method according to an embodiment of the present invention is applied.

As shown in Fig. 4, steel grades transmitted from the mill initial setting computer 410, furnace ash time, furnace extraction temperature, plate width, mill entry and exit side plate thickness, roll diameter, load cell 105, thickness gauge ( 411 and the rolling load, thickness, rolling speed, etc. measured by the speed meter 412 are received by the AGC gain setting device 409 and the rolling load filtering device 413.

Using the received data, the AGC gain setting device 409 performs a roll eccentric frequency calculation, a filter design for extracting skid mark thickness deviation, a skid mark thickness deviation calculation, and the like. By setting the AGC gain of the thickness control device 107 through the AGC gain learning using the skid mark thickness deviation and a table representing the relationship between the extraction temperature, the plate width, the flame retardant entry and exit plate thickness and the appropriate AGC gain, Allows to control the thickness deviation caused by the mark.

In the rolling load filtering device, the thickness control device 107 calculates the roll eccentric frequency and the rolling load from which the rolling load variation component due to the roll eccentric is removed, thereby minimizing the thickness variation due to the roll eccentricity.

While the invention has been described above based on the preferred embodiments thereof, these embodiments are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention will be limited only by the appended claims, and should be construed as including all such changes, modifications or adjustments.

According to the present invention as described above, by providing a thickness control method through the rolling load filtering and the prediction of the skid mark thickness deviation, to control the thickness variation caused by the skid mark, to minimize the thickness variation due to the roll eccentricity, the thickness quality degree Has the effect of improving.

Claims (4)

In the thickness control device of the continuous rolling mill to perform the automatic plate thickness control (AGC) by using the plate thickness deviation, Various parameters for thickness deviation prediction are input, roll eccentric frequency calculation, filter design for skid mark thickness deviation extraction and skid mark thickness deviation calculation are performed, and the table and skid mark thickness deviation that express the relationship between the appropriate AGC gain are obtained. An AGC gain setting unit for setting AGC gain through learning AGC gain; A rolling load filtering unit which receives various parameters for predicting thickness deviation and calculates a rolling load from which a rolling load component having a frequency equal to or greater than a roll eccentric frequency is removed from the rolling load due to the roll eccentricity; And And a thickness controller for controlling thickness by receiving data from the rolling load filtering unit and the AGC gain setting unit and minimizing the thickness variation due to the roll eccentricity. The method of claim 1, The various parameters may be any one of a steel grade, a furnace ash time, a furnace extraction temperature, a plate width, a plate thickness on a rolling mill side, a roll diameter, a load cell, a thickness gauge, and a speed gauge measured by a rolling mill, a thickness, and a rolling speed. The thickness control apparatus of the continuous rolling mill characterized by the above. In the thickness control method of the continuous rolling mill to perform the automatic plate thickness control (AGC) using the plate thickness deviation, AGC gain is set in consideration of steel grade, furnace ash time, furnace extraction temperature, plate width, rolling mill entry and exit plate thickness and so on to control thickness deviation caused by skid marks, and then AGC gain using skid mark thickness deviation. Optimizing through learning; Removing a rolling load component having a frequency greater than or equal to the roll eccentric frequency from the rolling load by using the optimized value to minimize thickness variation due to roll eccentricity; And Minimizing thickness variation due to roll eccentricity using the value from which the rolling load component is removed; Thickness control method of a continuous rolling mill comprising a. The method of claim 3, wherein The first step is, Calculating a roll eccentric frequency for each stand; A sub-step of filtering a thickness to remove a thickness component having a frequency greater than or equal to the minimum among the roll eccentric frequencies of each stand; A sub-step of detecting a maximum minimum thickness within the skid mark period from which the thickness component has been removed, and obtaining a difference between the maximum minimum thicknesses and making this value a skid mark thickness deviation. Control method.