JPH0857593A - Slab width control method in continuous casting equipment - Google Patents

Abstract

(57) [Summary] [Purpose] A slab width control method for continuous casting equipment that improves the prediction accuracy of the slab width prediction value to prevent the generation of surplus material and improve the yield. [Structure] Based on the manufacturing and work information from the vidicon 1 and the data from the model learning function 25, the slab width prediction function 21
In the slab width prediction by the multiple regression model in, the width change schedule creation function 22 from the obtained slab width prediction value determines the mold upper end width setting value and the width change start position based on the width change start position determination rule, Preset function 2
4 presets the control system, and the continuous casting equipment 3 is automatically controlled by the electric microcomputer according to the preset value. The operation data such as the casting speed and the product slab width are sampled by the instrumentation microcomputer 6 and checked by the model learning function 25 to build the model.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to slab casting control in a continuous casting facility, and more particularly to a slab width control method for controlling the product width size of a custom-made slab to match the order width size in a continuous casting facility. It is about.

[0002]

2. Description of the Related Art For example, in a bending type continuous casting facility, a tundish that functions as a distributor of molten steel is disposed at the lower part of a pot in which molten steel from a blast furnace is put, and the casting speed is kept constant. A coagulation unit is connected to the dish. The solidification section is composed of a mold having a primary cooling function, a cooling zone equipped with a spray (secondary cooling), a large number of curved rolls, and the like. Further, a dummy bar (stop bar), a cutting device, etc. are connected to the solidification section.

In continuous casting equipment, a plurality of solidification parts are connected in parallel to one tundish, and a plurality of solidification parts (usually 2
A method of casting a slab (strand) of a book (multi-strand method) is generally used.

By the way, in the multi-strand type continuous casting equipment, the slab width mismatch (difference between the manufacturing specification and the product width) is the largest factor of the deterioration of the quality straightness rate. For specific examples of slab width control, see, for example, Japanese Patent Publication No. 3-7.
No. 1213 is known. In this case, based on the product width of the custom-made slab, the conversion rate using the casting speed during casting slab production and the type of metal, etc.
The slab width was controlled by determining the mold width.

As for the position to start changing the mold width, the product widths of the custom-made slabs being cast are sequentially compared, and the custom-made slabs having a difference in product width of a specified value or more are specified as the slabs to be changed in width. It is said that it is calculated from the expected casting length of the tip of the width change target slab, a predetermined width change speed, a product width difference, and the current casting speed.

[0006]

However, in the above-mentioned conventional technique, the shape of the slab of the width changing portion has to be a trapezoidal shape due to facility restrictions. In addition to the above calculation method, it is necessary to move the width changing position back and forth in consideration of the prevention of excess material.

Further, when the width cannot be changed due to operating conditions despite the existence of the width-change target slab, in consideration of prevention of generation of surplus material of the slab during that period. It is necessary to determine the target ingot width and determine the target value of the product width for completing the width change of the uncast ingot while the width can be changed.

Then, the determination of the change start position of the mold width is
Since it is carried out manually by the operator, it is highly dependent on the empirical rule, and the result is easily influenced by the skill of the operator. That is, the variable width operation is, as shown in FIG. 7, a steady portion in which slabs of the same width are roughly divided (a portion in which the upper end width of the mold is finely adjusted by the experience of the operator while referring to the measured value of the slab width). And the variable width part when casting slabs of different widths (using a simple calculation formula, manually calculate the upper mold width of the next slab and manually calculate the variable width start timing based on the work standard. It can be considered by dividing it into parts for manually operating the control device), but any operation depends on the operator manually calculating the set value according to various standards and the manual operation of the device.

As described above, most of the conventional contraction (or expansion) process of the cast slab has not been elucidated and accurate modeling has not been performed. Large and small errors occur between the product widths of the custom-made slabs, and during that time, the operator's intervention increases, which causes surplus material, resulting in a decrease in yield.

Therefore, an object of the present invention is to provide a slab width control method in a continuous casting facility capable of preventing the production of surplus material and improving the yield.

[0011]

In order to achieve the above object, the present invention provides operating conditions for casting a custom-made ingot in a continuous casting facility equipped with a mold width varying device for varying the mold width. The amount of contraction or expansion of the slab in the mold is predicted on the basis of this, and the mold width is determined based on this prediction result.

Further, the shrinkage amount or expansion amount of the slab is predicted by using a multiple regression model.

Further, the change start position of the mold width is determined using a width change rule created based on the upper and lower limit values of the product width of the custom cast piece and the quality evaluation information on the custom cast iron piece width. .

[0014]

According to the above-mentioned means, the mold width for casting a slab of a certain product width is determined by the amount of shrinkage of the slab in the mold based on the operating conditions for casting the custom slab. Alternatively, it is performed based on the result of predicting the expansion amount. Therefore, generation of surplus material can be prevented, and the yield can be improved. In addition, the burden on the operator can be reduced.

Then, the width of the cast product, which is a factor of generation of surplus material, is determined by the accurate modeling using the multiple regression model based on the operating conditions without depending on the conversion table or the like in determining the mold width. , It is possible to improve the accuracy of slab width prediction, which reduces the difference between the product width and the product width of the custom cast product.

Further, conventionally, the operator determines the change start position of the mold width manually, whereas the upper and lower limit values and the order of the product width of the custom slab calculated from the equipment and operating capacity of the lower process By determining using the width change rule created based on the quality evaluation information about the width of the slab, it is possible to perform the process of minimizing the generation amount of the surplus material.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flow chart showing a processing example of a slab width control method in continuous casting according to the present invention. FIG. 2 is a functional block diagram of a control system according to the slab width control method in continuous casting of the present invention. FIG. 3 is a schematic diagram showing a schematic configuration of a mold portion of the continuous casting equipment shown in FIG.

As shown in FIG. 2, a proc computer (process computer) 2 for controlling the continuous casting (CC) process is connected under a vidicon (business computer) 1 for controlling the entire operation system of the factory. An electric microcomputer (microcomputer) for controlling the speed of the pinch rolls of the solidification part in the continuous casting equipment 3 is connected to the process control 2, and the casting speed, the secondary cooling water amount, the product from the continuous casting equipment 3 are further connected. An analysis database 5 is connected, which stores operation data from an instrumentation microcomputer 6 that fetches and processes data such as slab width.

Manufacturing specifications (billing values such as slab widths), work standards, work instruction information, etc. are given from the vidicon 1 to the proccon 2 via a communication line, and the procicon 2 is provided with the information contents from the vidicon 1 , Slab width prediction function 21, width change schedule creation function 22, operation status monitoring function 2
3, processing by the preset function 24, model learning function 25, and coefficient unit 26 is performed.

Particularly, on the slab width prediction function 21, slab width prediction is performed by multiple regression analysis using a multiple regression model.

The regression equation of the multiple regression model in this case is as follows.

W = a₀+ A₁× Vz + a₂× Q + a₃× W_MD
+ A_Four× C where W: slab width predicted value Vz: casting speed when passing through the meniscus W _MD: Mold top width Q: Cooling strength (secondary cooling water flow rate calculation coefficient) C: Target C% a₀ : Parameter a₁ : 〃 a₂ : 〃 a₃ : 〃 a_Four : Given in 〃. In the equation, “W” is the so-called regression equation
It is an objective variable that represents a predicted objective value, and is “Vz, W_MD, Q,
C ”is the dependent variable (or independent variable) that is measurable data.
Number) and "a₀~ A_FourIs a parameter (or regression
Number), "C" represents the target variable for the error
It

The predictive calculation by the multiple regression analysis of the actual festival performed by the system is manually calculated by the model learning function 25 (WS or the like) based on the actual operation data stored in the analysis database 5 or prepared separately. The coefficient obtained is output by using the multiple regression analysis routine etc. in the statistical program / package.

The analysis procedure is as a variable selection process. First, operation data “Vz” and “W” which are dependent variables to be sampled.
For example, a prediction error of each parameter “a _{0 to} a ₄ ”, which is a corresponding unknown constant, is calculated by a method of obtaining a solution of simultaneous equations by the least squares method from “ _MD ”, etc. to reduce the prediction error. In addition, the result of repeated processing including empirical rules such as confirmation of matching with actual operation data. For example, a ₀ = −29.729 a ₁ = 33.255 a ₂ = −0.0594 a ₃ = 1.00371 a ₄ = 47.7291.

Thus, if the parameter values are determined,
Since the dependent variable “Vz” ... Is a measurable value, the slab width prediction that is a target variable when the dependent variable has a specific value with less prediction error in the slab width prediction function 21 than the regression equation described above The value "W" will be obtained.

In addition to this system, continuous casting equipment 3
A mold part as shown in FIG. 3 is provided inside, and the mold part comprises a pair of short pieces 7a and a pair of long pieces 7b for varying the mold width, and the inclination of the short piece 7a of the mold width varying device 7 is mechanically adjusted. The taper meter 8 which indicates to, the eccentric cam 9 which is also a measuring element for measuring the inclination of the short piece 7a, the motor 10 which is a drive source for moving the short piece 7a for varying the mold width, and the rotational speed of the motor 10 are detected. Rotation detector 1
1. The entire system is configured to include each of the control devices 12 that control the motor 10 based on the rotation detection value and the taper detection value by the eccentric cam 9.

Next, the control processing of the present invention will be described with reference to FIG. First, the process controller 2 receives manufacturing specifications, work standards, work instruction information, etc. from the vidicon 1 (S10).
1), the process control 2 is the order information of the vidicon 1, the coefficient part 26
The prediction process of the slab width prediction function 21 for obtaining the slab width prediction value "W" by the regression equation described above is executed based on the data from (S102).

That is, in S102, a normal prediction process for setting a standard operating state (casting speed, etc.) based on work instruction information from the vidicon 1 and a main slab width prediction value "W" of the present invention are set. The slab width prediction process is performed, and the prediction result is displayed and guidance is provided.

Next, based on the obtained slab width predicted value "W", the width changing schedule forming function 22 performs a forming process (S103).

This width change schedule creation process includes three calculation contents. (1) Obtain the mold upper end width setting value from the slab width prediction value “W”. (2) Obtain the slab width upper and lower limits from the slab width predicted value “W”. (3) Obtain the width change start casting length from the upper and lower limits of the slab width.

First, the mold upper end width setting value of (1) is as follows.

W _MD = W ₀ + W ₁ However, W _MD : Mold width set value W ₀ : Mold upper end width currently being cast W ₁ : Width deviation value (claimed value W _S -Wmin). This set value is displayed on the display device.

Further, in the width change schedule creation process,
In order to reduce the width mismatch of the width varying portion, the width varying start position that efficiently uses the slab width allowable range is calculated. Since the slab width allowable range changes depending on the slab shape (width variation rank), the slab width allowable range is determined by obtaining the width variation rank from the slab width prediction value.

Specifically, as the processing of (2), as shown in FIG. 4, the upper and lower limits of the slab width are obtained from the fluctuation rank grasped from the fluctuation amount (ΔWmm) in the slab width and the demanded slab width. Is.

As the processing of (3), a width change start position determination rule (casting speed, width change speed, and timing within a permissible range of front and rear slabs) that refers to quality evaluation information (remaining material, width strict information) are calculated. The width change start position is determined based on the upper and lower limits of the slab width. In this way, we aim to set the mold top width with as little error as possible, and also pay attention to the product yield that suppresses the generation of excess material.

Next, based on the results of the mold upper end width set value and the width change start casting length thus obtained, the preset function 24
Is executed. In this processing, the operating state is monitored based on the monitoring result provided from the operating state monitoring function 23, and it is determined whether the operating state as shown in FIG. 5 has occurred. Superheat or the like is calculated based on the determination result, whether or not the width can be changed is checked, and presetting for the control system is performed or stop is executed (S104).

The operation data such as the casting speed "Vz", the secondary cooling water amount coefficient "Q", the mold upper end width "W _MD ", etc. during the operation of the continuous casting equipment 3 thus controlled, and the slab width meter are used. The slab width measurement value of the product is taken into the instrumentation microcomputer 6, the signal format is converted, and the analysis database 5 is used.
Stored as actual operation data.

Based on the actual operation data stored in the database 5, the model learning function 25 verifies and corrects the deviation between the multiple regression model and the actual operation data, and learns by regression diagnosis in order to deepen model fitting and improve prediction accuracy. Perform processing.

There are various methods for regression diagnosis. Residual analysis for checking the fit from the residual (error) indicating the difference between the slab width predicted value “W” due to slab width mismatch and the actual product slab width. Is generally used, and residual plotting or residual histogram creation is the simplest and most reliable checking method.

FIG. 6 is a histogram showing the width of each product slab on the vertical axis for n product samples, which can be easily checked if there is an abnormal distribution.

FIG. 7 is a scatter diagram format in which, with respect to the product sample of n = 585, the slab width predicted value “W” is plotted on the vertical axis and the product slab width is plotted on the horizontal axis, and the numerical values of each sample are plotted around the regression line. Is a residual plot of. The plot position in the figure means that the residual is smaller and the prediction accuracy is higher as the plot position is closer to the regression line. In the present embodiment, finally, as shown in FIG.
A high prediction accuracy of an average error σ = 8.5 mm is obtained.

As described above, in this embodiment, since the multiple regression model is introduced for the slab width prediction, the product slab originally intended for continuous casting equipment is bent, returned and deformed by drooping, heat shrinkage due to cooling, etc. It was difficult to match the predicted value with the product slab width because a complicated process was performed. However, in the regression equation representing the multiple regression model of this example, the dependent variable for predicting the objective variable “W” was set to the prediction accuracy. Even if the number is increased in response to a complicated process in order to raise the number, the calculation does not result in a linear calculation and the form of the prediction calculation does not become complicated.
It is possible to improve the prediction accuracy as compared with the conventional table method and the like, and as a result, the product yield is improved.

[0044]

As described above, the slab width control method for continuous casting equipment according to the first aspect of the present invention is a continuous casting equipment equipped with a mold width varying device for varying the mold width. The amount of shrinkage or expansion of the slab in the mold is predicted based on the above, and the mold width is determined based on this prediction result, so it is possible to prevent the generation of excess material and improve the yield. In addition, the burden on the operator can be reduced.

In the slab width control method in the continuous casting equipment according to the second aspect, since the shrinkage amount or expansion amount of the slab is predicted using the multiple regression model, the prediction accuracy is increased and the product yield is improved.

In the slab width control method in the continuous casting equipment according to the third aspect, the change start position of the mold width is created based on the upper and lower limit values of the product width of the custom slab and the quality evaluation information on the custom slab width. Since it is determined using the width change rule described above, it is possible to minimize the amount of surplus material generated.

[Brief description of drawings]

FIG. 1 is a flowchart showing a process of a slab width control method in a continuous casting facility of the present invention.

FIG. 2 is a functional block diagram of a control system according to a slab width control method in a continuous casting facility of the present invention.

FIG. 3 is a schematic diagram showing a schematic configuration of a mold part of the continuous casting facility shown in FIG.

FIG. 4 is an explanatory diagram showing a method of calculating a width change start position according to the present invention.

FIG. 5 is an explanatory diagram showing detailed contents of a width change prohibited operation state in the present invention.

FIG. 6 is a schematic diagram showing a product width prediction model obtained by the present invention.

FIG. 7 is a scatter diagram showing prediction results according to the present invention.

FIG. 8 is an explanatory diagram showing an outline of a conventional variable width operation.

[Explanation of symbols]

 1 Vidicon 2 Procon 3 Continuous casting equipment 4 Electric microcomputer 5 Database 6 Instrumentation microcomputer 7 Mold width variable device 8 Taper meter 9 Eccentric cam 10 Motor 11 Rotation detector 12 Control device 21 Slab width prediction function 22 Width change schedule creation function 23 Operation State monitoring function 24 Preset function 25 Model learning function 26 Coefficient part

Claims (3)

[Claims] 1. In a continuous casting facility equipped with a mold width varying device for varying the mold width, the shrinkage amount or expansion amount of the slab in the mold is predicted based on the operating conditions for casting the custom slab. , A slab width control method in continuous casting equipment, characterized in that the mold width is determined based on this prediction result. 2. The slab width control method in a continuous casting facility according to claim 1, wherein the shrinkage amount or expansion amount of the cast piece is predicted by using a multiple regression model. 3. The change start position of the mold width is determined using a width change rule created based on the upper and lower limit values of the product width of the custom-made slab and the quality evaluation information on the custom-made slab width. The slab width control method in the continuous casting equipment according to claim 1.