JPS6366607B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is applied to the rolling of H-shape, I-shape, channel steel, etc. by adjusting the roll gap amount of the finishing universal rolling mill during rolling. This invention relates to a method for controlling plate thickness.

(Prior art) Shape steel is rolled by continuously rolling steel extracted from a heating furnace using a rough rolling mill, an intermediate rolling mill, and a finishing mill that are arranged in series to produce products with predetermined product dimensions. It is something to do. The length of the product rolled by the finishing mill for continuous rolling is 240m.
At the leading and trailing ends, a temperature drop (thermal rundown) of approximately 20°C occurs due to the rolling time. Due to this temperature drop, the deformation resistance of the steel material increases as it goes toward the rear end even within the same bar, and the finished thickness of the product increases from the front end to the rear end, resulting in a disadvantage that the products do not have the same dimensions.

Several documents have been published regarding thickness control of section steel. For example, in JP-A-50-84447, the thickness of the web portion and the left and right flange portions are measured using a thickness gauge, and the rolling reaction force and roll gap of the horizontal roll and the left and right vertical rolls are measured using a load cell and a gap measuring device, respectively. Based on these measured values, the thickness of each part is calculated using the hook method, taking into account the influence between the web and the left and right flanges, and the horizontal roll and left and right vertical roll are calculated based on the deviation from the target value. A technique for controlling the amount of reduction is known. This method does not take temperature changes due to thermal rundown into consideration, and control is complicated.

(Objective of the Invention) The present invention improves yield by controlling the roll gap amount of horizontal rolls and vertical rolls using model equations for temperature deviation in the longitudinal direction of the rolled material and changes in thickness of webs and flanges due to thermal rundown. The purpose is to manufacture shaped steel products with uniform dimensions in the longitudinal direction.

(Summary of the Invention) To achieve the above object, the sheet thickness control method of the present invention provides a method for controlling the thickness of a material to be rolled by using a thermometer placed near the exit or entry side of a universal rolling mill in a universal rolling method for section steel. Measure the temperature in the longitudinal direction of the flange section and flange section to find the temperature deviation from the temperature setting value, and measure the horizontal roll and vertical roll reaction force of the rolling mill at the temperature measurement position of the temperature setting value using a reaction force meter. Then, the horizontal roll and vertical roll gap deviations are calculated from the temperature deviation and the measured reaction force, and based on the calculated values, the horizontal roll and vertical roll reduction devices of the universal rolling mill are driven to control the horizontal roll and vertical roll gap amounts. It is characterized by

(Structure of the Invention) The present invention will be described in detail below with reference to an embodiment shown in the drawings.

Figure 1 shows the rolled shape of H-section steel, a typical section steel product. Reference numerals 1 and 2 indicate a web portion and a flange portion, respectively, which are rolled into a universal shape by horizontal rolls and vertical rolls (not shown). Figure 2 shows the relationship between the temperature of H-section steel (horizontal axis) and the thickness of the web and flange (vertical axis) for three sizes: H396×174,
This is a conceptual diagram of H200×200 and H198×99 (the product board thickness also differs in three sizes). As can be seen from the figure, a temperature difference occurs from the tip to the rear end of the shaped steel for all three sizes, and as a result, the thicknesses of the web and flange each increase. The feature of the present invention is that the roll gap of the horizontal roll and vertical roll is controlled by using model equations for changes in the thickness of the web and flange due to this temperature deviation. The principle will be explained below. Letting the rolling reaction force be P, the reaction force equations for the web and flange portions are given by the following equations.

Web rolling reaction force P _h = K _nW・F _dW・Q _gW ……(1) Flange rolling reaction force P _v =K _nF・F _dF・Q _gF ……(2) Here, K _nW and K _nF are separated. K _dW and F _dF are the projected contact areas of the web and flange, respectively, and Q _gW and Q _gF are the load coefficients of the web and flange, respectively.

Now, assuming that the temperature changes from T to T' in the longitudinal direction of rolling, the reaction forces of the web and flange are expressed by the following equations.

P _h ′＝K _nW ′・F _dW・Q _gW ……(1)′ P _v ′＝K _nF ′・F _dF・Q _gF ……(2)′ (1), (1)′ and (2) , (2)′, each reaction force deviation due to temperature deviation is as follows.

P _h ′／P _h ＝K _nW ′／K _nW ……(3) P _v ′／P _v ＝K _nF ′／K _nF ……(4) The restraint deformation resistance is given by the following formula from the Yoshimoto-Misaka formula. It is being

K _nW orK _nF = 1.15exp (0.126−1.75C+0.594C ² +2851+2968C−1120C ² /T)・ε ^0.21・ε〓 ^0
.13 where C is the carbon content of the steel material, ε, ε〓 are the strain and strain rate of the steel material, and T is the temperature of the section steel. When the temperature changes from T to T′, K _nW ′=K _nW・exp{α・(1/T′−1/T)}……(5
) K _nF ′=K _nF・exp{α・(1/T′−1/T)}……(6
) Here, α=2851+2968C−1120C ² . Therefore, from equations (3) and (4), the rolling reaction force deviation of the web and flange can be determined as follows.

ΔP _h = ΔP _h ′−P _h =P _h・(exp{α(1/T′−1/T
)}− 1) ……(7) ΔP _v = ΔP _v ′−P _v =P _v・(exp{α(1/T′−1/T
)}-1) ...(8) When the rolling reaction force deviation is given by equations (7) and (8), the thickness deviation at the exit side of the rolling machine for each web and flange is
It is determined by the following formula using plate thickness control using BISRA-AGC.

Δh _W = ΔS _W + ΔP _h ／M _W …(9), Δh _F = ΔS _F +ΔP _v ／M _F …(10) Here, Δh _W , Δh _F …Outside plate thickness deviation of web and flange portion ΔS _W , ΔS _F ... Roll gap deviation of the web and flange M _W , M _F ... Mill constant Therefore, in order to make the thickness deviation on the exit side of the rolling machine zero, the roll gap of each horizontal roll and vertical roll should be controlled using the following formula. It will be a good thing.

ΔS _W =−ΔP _h /M _W =−P _h /M _W (exp{α(1/T′−1/
T)}- 1) ...(11) ΔS _F =-ΔP _v /M _F =-P _v /M _F (exp{α(1/T'-1/
T)}-1) ...(12) Here, M _W and M _F are the mill constants of the horizontal roll and vertical roll, respectively.

Equations (11) and (12) are model equations for the roll gap control of the horizontal and vertical rolls in order to eliminate the thickness deviation at the exit side of the rolling mill due to thermal rundown in the longitudinal direction of the section.

Figure 3 is an example of a configuration diagram of automatic plate thickness control using this model formula, where 3 is a steel material detector installed on the exit side of the universal rolling mill to detect the leading and trailing ends of the shaped steel, and 4 and 5 are the shaped steel detectors. This thermometer measures the temperature of the steel web portion and flange portion, and is installed at the same position as the steel material detector 3. Also, it is installed near the rolling mill to reduce lag time. 6 is a pulse transmitter, 7 is a
11 and 12 are calculation units that calculate formulas, 8 is a horizontal roll of the universal rolling mill, 9 is a vertical roll of the universal rolling mill, 10 is a horizontal roll reduction drive motor, 1
1 is a horizontal roll reduction system, 12 is a vertical roll reduction drive motor, 13 is a vertical roll reduction system, 14 is a reaction force meter,
15 is a section steel.

(Function of the Invention) An example of the function based on the above configuration applied to the final stage universal rolling mill in a row of finishing universal rolling mills will be described. When the tip of the material to be rolled 15 is bitten by the universal rolling mill, the pulse generator 6 attached to the drive motor 10 of the horizontal roll starts counting. When the tip of the rolled material is detected by the steel material detector 3, the arithmetic unit 7 determines whether the rolled material 15 after the steel material detector 3 is detected based on the count value of the pulse transmitter 6.
Calculate the length of. The temperature at the temperature measurement point (distance Lm) from the tip of the rolled material 15 is measured using the web section and flange section thermometers 4 and 5, and the temperature set value T is determined.
It is stored in the arithmetic unit 7. Thereafter, the temperature T' of the web section and flange section at each temperature measurement point is actually measured, and the temperature deviation is determined. Further, the horizontal roll reaction force and the vertical roll reaction force at the temperature measurement position of the temperature setting value T are measured by the reaction force meter 14 attached to the horizontal roll and vertical roll 9 of the universal rolling mill, and are input into the calculation device 7 and stored. be done. The arithmetic unit 7 calculates the horizontal roll gap deviation and the vertical roll gap deviation from the temperature deviation and reaction force using the model equations (11) and (12). The calculated value is output to the horizontal roll reduction system 11 and the vertical roll reduction system 13, and the horizontal roll reduction drive motor 10 and the vertical roll reduction drive motor 12 are driven. Thereafter, by repeating this calculation operation only by measuring the temperature at T', the plate thickness deviation due to thermal rundown is controlled to be zero. Rolled material 15
When the rear end passes through the final stage universal rolling mill, plate thickness control is completed, the horizontal rolls and vertical rolls are returned to the initial roll gap value, and the next steel material is waited for.

In addition, if a thermometer is installed near the entrance side of the final universal rolling mill to control the plate thickness, the steel material detector 3 and thermometers 4 and 5 are placed at the same position on the entrance side of the final universal rolling mill, and the pulse transmitter 6 is attached to the final front stage universal rolling mill. The pulse generator 6 starts counting in response to the metal-in signal when the tip of the rolled material 15 is caught in the final stage universal rolling mill, and when the steel detector 3 detects the tip of the rolled material 15, the arithmetic unit 7 generates a pulse. The length of the rolled material 12 after the detector 3 is calculated based on the count value of the transmitter 6, and the length Lm set from the tip of the rolled material 15 is calculated.
The temperature setting value T of the web portion and flange portion is measured using the thermometers 4 and 5 based on the calculated length value, and is stored in the arithmetic unit 7. Also, the signal that this temperature measurement point bit into the final universal rolling mill is the metal-in signal of the final universal rolling mill and the pulse transmitter 6.
The horizontal roll and vertical roll reaction forces at the temperature measurement point position are determined by the reaction force meter 14, and are similarly input to the calculation device and stored.
After that, the temperature of the web part and flange part at each temperature measurement point
T' is actually measured and calculations similar to those described above are performed to control the plate thickness.

(Example) Conventionally, the product thickness deviation due to thermal rundown (20℃) from the tip (temperature setting value) to the rear end of the section steel was max 0.4 m/m, but by implementing the present invention, the deviation was reduced to 0.1 m/m. m, resulting in a significant improvement in dimensional accuracy.

(Effects of the Invention) The automatic plate thickness control method of the present invention greatly reduces dimensional variations in plate thickness and improves product yield by about 0.5%, which is a significant effect.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the rolled shape of H-section steel, Figure 2 is a diagram explaining the rolled shape of H-beam steel.
Figures a to f are graphs showing the relationship between temperature, web thickness, and flange thickness, and Figure 3 is a block diagram showing an embodiment of the present invention. In the drawing, 15 is a section steel, 4 and 5 are thermometers, 14 is a reaction force gauge, 11 and 13 are rolling systems, 10 and 12 are drive motors thereof, and 7 is a calculation device.

Claims (1)

[Claims] 1. In the universal rolling method for section steel, the temperature in the longitudinal direction of the web part and flange length of the material to be rolled is measured using a thermometer placed near the exit or entry side of the universal rolling mill, and the temperature deviation from the temperature setting value is determined. At the same time, the horizontal roll and vertical roll reaction forces of the rolling mill at the temperature measurement position of the temperature setting value are measured with a reaction force meter, and the horizontal roll and vertical roll gap deviations are calculated from the temperature deviation and the measured reaction force. 1. A method for automatically controlling the thickness of a section steel, comprising controlling the horizontal roll and vertical roll gap amounts by driving the horizontal roll and vertical roll reduction devices of a universal rolling mill based on calculated values.