KR20080058641A - Temperature controlling method and apparatus in hot strip mill - Google Patents

Abstract

A method and an apparatus for controlling temperature in hot rolling are provided to measure a middle temperature and control water injection amounts of a feed forward bank and a feed back bank by calculating first and second water cooling amounts and setting water injection amounts of banks. A method for controlling temperature in hot rolling comprises the steps of: correcting learning coefficient of a previous coil(S1); collecting finishing mill output side temperature, winding temperature, middle temperature, and rolling plate moving speed(S2); calculating an air cooling amount and a water cooling amount(S5); calculating a first water cooling amount and setting respective water injection amounts of first banks(S6); and calculating a second water cooling amount and setting respective water injection amounts of second banks(S7).

Description

Temperature controlling method and apparatus in hot rolling

1 is a view for explaining the importance of the intermediate temperature control, a view showing the state of material change by temperature of the steel,

2 is a diagram showing the configuration of a temperature control apparatus for hot rolling according to the prior art;

3 is a view showing a change in heat flux coefficient with temperature change;

4 is a view for explaining a temperature control method of the temperature control device of FIG.

5 is a view for explaining a temperature control method of hot rolling according to an embodiment of the present invention;

6 is a view showing the configuration of a temperature control device of hot rolling according to an embodiment of the present invention;

7 is a view showing the temperature change of the rolled plate according to the temperature control device of the hot rolling of the present invention;

8 shows an external view of an intermediate thermometer according to the present invention, and

9 is a view showing an example of an intermediate thermometer installed in the ROT apparatus of FIG.

The present invention relates to an apparatus and a method for controlling the temperature of a rolled plate, and particularly in the case of steel grades requiring intermediate temperature control of high-grade steel, it is possible to more precisely control the CT (Coil Temperature) temperature using the temperature measured from the intermediate thermometer. It relates to a temperature control device of hot rolling.

In cooling on a run out table (ROT) in the conventional hot rolling, a thermometer is not provided in the intermediate region of the ROT apparatus. Here, the ROT device is a device for transferring the rolled strip (Strip) out of the finishing mill to the winding machine.

In order to produce high-grade steel such as DP (Double Phase) steel, although the technology for precisely controlling the intermediate temperature is required, its control is impossible and the intermediate temperature control performance as well as the coiling temperature (CT) temperature is relatively high. It is lowered.

This is a problem in steel grade where high strength material or intermediate temperature control is particularly important, and cause material variation in the longitudinal direction, so the problem of temperature control between banks using intermediate temperature must be solved for the production of high grade steel.

Therefore, in the case of feedforward and feedback control in the coil length direction using the intermediate temperature, a technique for more precisely controlling the intermediate temperature is required.

1 is a view for explaining the importance of the intermediate temperature control, it is a view showing the state of material change for each temperature of the steel grade.

When the temperature of the rolled sheet is gradually lowered at the exit temperature FDT to reach the intermediate temperature section MT, the rolled sheet has a ferrite structure. In particular, in the intermediate temperature section MT, the ferrite transformation fraction becomes maximum.

When the temperature of the rolled sheet is lowered past the intermediate temperature section MT, the rolled sheet has a winding temperature CT through the bainite and martensite structures Ms.

Steel grades having such metallurgical characteristics include DP steel and trip steel, and are classified as high grade steels used as automotive materials. In particular, the intermediate temperature control is a factor in determining the material of the steel, and the air cooling time is also an important factor in controlling the intermediate temperature.

2 is a diagram showing the configuration of a temperature control apparatus for hot rolling according to the prior art.

Referring to FIG. 2, the temperature control device includes a ROT device 10 and first to sixteenth banks B1 to B16 provided above the ROT device 10. The first to fourteenth banks B1 to B14 are used as feedforward banks FFB that control the amount of water supplied according to the temperature measured by the finishing rolling exit thermometer 12 installed at the exit side of the finishing mill 11. The fifteenth and sixteenth banks B15 and B16 are used as a feedback bank FBB that controls the amount of water supplied according to the temperature measured by the winding thermometer 13 installed on the winding machine (not shown).

Accordingly, the conventional temperature control device gradually cools the water through the water feeding operation of the feed forward bank FFB while having the exit temperature FDT in the finishing mill 10 and the output rolled plate being transferred through the ROT device 10. To reach an intermediate temperature range MT. After the air-cooling time is given, the liquid is gradually cooled by water supply operation of the feed forward bank FFB and the feedback bank FBB while being transferred through the ROT apparatus 10 to reach the winding temperature CT.

However, the temperature control method according to the prior art has a problem that the control of the winding temperature (CT) is difficult.

3 is a view showing a change in the heat flux coefficient according to the temperature change, referring to FIG. 3, it can be seen that the heat flux coefficient varies greatly depending on the rolling speed.

In particular, the heat flux coefficient is significantly different at low temperatures, the DP steel to be controlled in the present invention is also a low temperature of about 200 degrees, so as mentioned above, the heat flux coefficient is greatly different so that the control of the coiling temperature (CT) is very high. Becomes difficult.

4 is a view for explaining a temperature control method of the temperature control device of FIG.

In Fig. 4, 590 DP steel is adopted as an example of the steel grade. FDT is the filament rolling side temperature, MT is the intermediate temperature, LT is the cold winding temperature, and CT is the hot winding temperature, respectively.

4, it can be seen that the finishing rolling exit temperature FDT is controlled to some extent, but the middle temperature MT is largely hunted in the middle. The low temperature winding temperature (LT) also fluctuates significantly and the variation of the temperature between the maximum value and the minimum value can be seen that the deviation of about 300 degrees or more.

Therefore, it can be seen that the technique of securing the air cooling time at the intermediate temperature and controlling the intermediate temperature is very important for increasing the precision of the winding temperature control.

An object of the present invention for solving the above problems is to provide a method and method for controlling the temperature of hot rolling to more precisely control the intermediate temperature.

In order to achieve the object of the present invention as described above, the method of controlling the temperature of the hot rolling of the present invention comprises the steps of correcting the learning coefficient of the coil previously worked, the finishing rolling side temperature, winding temperature, intermediate temperature and rolling plate movement Collecting a speed, calculating an air cooling fall amount using the filament rolling exit temperature, calculating a water cooling fall amount using the air cooling fall amount and a winding temperature target value, and firstly according to the water cooling fall amount and the intermediate temperature target value. Calculating a water drop amount, setting a main water amount of each of the first banks according to the first water drop amount, calculating a second water drop amount using the water drop amount and the collected intermediate temperature, and And setting a main water amount of each of the second banks according to the amount of water cooling drop.

In order to achieve the object of the present invention as described above, the temperature control apparatus of the hot rolling of the present invention, the learning coefficient correction unit for correcting the learning coefficient of the coil previously worked, the finishing rolling side temperature, winding temperature, the intermediate temperature, And calculating an air cooling fall amount using the historical data collecting unit for collecting a rolling plate moving speed, an intermediate target temperature setting unit for setting an intermediate temperature target value, and the finishing rolling exit temperature, and using the air cooling drop amount and a winding temperature target value. After calculating the amount of water cooling drop, the water-cooled drop amount calculating unit for calculating the first water cooling amount according to the water cooling amount and the intermediate temperature target value and calculates the second water cooling amount using the collected water temperature and the collected intermediate temperature, and the 1 A first main water bank setting unit configured to set a main water amount of each of the first banks according to the secondary water cooling amount; D) the secondary water bank setting unit for setting the primary water supply amount of each of the second banks, and the primary and second primary banks according to the setting result of the first main bank and the second main bank bank; It is provided with the water injection control part to control.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing in detail the operating principle of the preferred embodiment of the present invention, if it is determined that the detailed description of the related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In addition, the same reference numerals are used for parts having similar functions and functions throughout the drawings.

5 is a view for explaining a temperature control method of hot rolling according to an embodiment of the present invention.

First, in the first step S1, the learning coefficient f1 of the previously worked coil is corrected. The learning coefficient of the coil is an item that can increase the accuracy of control by accurately calculating the temperature invention amount by correcting the degree of the heat flux coefficient (Q).

In the second step S2, the finishing rolling exit temperature FDT, the intermediate temperature MT, and the winding temperature CT are collected (S2), and in the third step S3, the rolling plate movement speed is collected (S3). . In general, the temperature control of the ROT section is divided into an initial setting mode, a feed forward control mode, a feedback control mode, and a learning mode. In feedforward control mode, the number of headers of the bank controlled in the ROT section is determined by using the finishing rolling exit temperature (FDT) and the moving speed of the rolled sheet. In the feedback control mode, the winding temperature (CT) and the rolled plate are moved. The speed is used to determine the number of headers in the bank. The cooling pattern and rolling parameters are used for the two modes.

In the fourth step S4, it is determined whether the coil is for general continuous cooling or the front and rear stage separate cooling coils (S4). For ordinary steel, most are continuous cooling coils, which largely depend on the cooling pattern to determine the number of headers in the bank to be used. On the other hand, in the case of steel grades, the front and rear separate cooling coils are usually used as targets for the intermediate temperature, and the performance of the intermediate temperature is measured using the temperature calculated by the temperature calculation model, and the temperature measured through the thermometer is directly installed. It is divided into the case of use.

As a result of the determination in the fourth step S4, in the fifth step S5, the air cooling drop CT _air until the finishing rolling exit temperature FDT and the coiling temperature CT is calculated by Equation 1 below. Calculate according to

B = FDT × a + b

Where a, b, and A are coefficients, L is the length of the ROT section, and H is the thickness of the rolled sheet. V represents the moving speed of a rolled sheet, respectively.

In the sixth step S6, the temperature drop amount by actual water cooling is calculated between the finishing rolling exit temperature FDT and the winding temperature CT except for the air cooling drop amount calculated in the fifth step S5. Accordingly, the first water cooling drop amount ΔT ₁ is calculated according to Equation 2 (S6).

,

,

Here, ΔT ₁ represents the primary water cooling drop, and MT _T represents the intermediate temperature target value, respectively.

In the seventh step S7, the second water cooling drop amount ΔT ₂ is calculated using Equation 3 (S7).

Here, ΔT ₂ represents the primary water cooling drop and CT _T represents the winding temperature target value, respectively.

In the second step 8 (S8) in consideration with the computed through the sixth step (S6) 1 water-cooled drop (△ T ₁₎ and the water-cooling temperature drop by the bank in which operations (△ T _bi) according to the equation (4) Primary The amount of main water in the main water banks (for example, the first to eighth banks B1 to B8) is set.

Here, the length of each of the L _b banks, C is the specific heat, ρ is the specific gravity, and Q _i is the heat flux coefficient of the i bank.

And the ninth step (S9) in consideration with a seventh second water cooling calculated through the step (S7) drop (△ T ₂₎ and the water-cooling temperature drop by the bank in which operations (△ T _bi) according to the expression 42 The amount of water in the secondary water banks (for example, the ninth to fourteenth banks B9 to B14) is set.

On the other hand, if it is determined in the fourth step S4 that the continuous cooling coil, in the tenth step S10, the total amount of main water is set using Equations 1, 2, and 3 as in the prior art, and the eleventh step S11. ) Sets the main water quantity of each of the banks B1 to B14.

6 is a view showing the configuration of a temperature control device of hot rolling according to an embodiment of the present invention.

Referring to FIG. 6, the temperature control apparatus of the present invention includes a ROT apparatus 10, a first feed forward bank FFB1 including first to eighth banks B1 to B8, and ninth to fourteenth banks. A second feed forward bank (FFB2) including (B9 to B14), a feedback bank (FBB) including the fifteenth and sixteenth banks (B15, B16), and a rolling plate provided at the exit side of the finishing mill (11). A rolling-rolling-out-side thermometer 12 for measuring the exit temperature FDT of the coil, and a winding thermometer 13 and a ROT apparatus 10 installed on the winding machine (not shown) side to measure the winding temperature CT of the rolled sheet. Intermediate thermometer 20 for measuring the intermediate temperature (MT) of the rolled plate, the learning coefficient correction unit 30 for correcting the heat flux learning coefficient (f1), the exit temperature (FDT) of the rolled plate, winding Performance data collection unit 31 for collecting the temperature (CT), the intermediate temperature (MT) and the moving speed of the rolled plate, before and after judging whether the current rolling plate is the front and rear stage separate coolant However separate cooling determiner 32, a primary water-cooling for computing a first water cooling drop (△ T ₁₎ in accordance with the air-cooling drop amount calculating section 33, the equation (2) for calculating the air-cooling drop (CT _air) according to equation (1) drop amount calculating section 34, a second water-cooling drop amount in accordance with equation 3 (△ T ₂₎ the calculation secondary time naengryang operation unit 35, the set intermediate target temperature (36) for setting the intermediate temperature target value (MT _T) that And through the first main water banks B1 to B8 included in the first feed forward bank FFB1 according to the first water cooling amount ΔT ₁ and the water cooling temperature drop amount ΔT _bi for each bank of Equation 4. The second feed forward bank (FFB2) according to the primary main water bank setting unit 37 for setting the primary main water supply amount, the secondary water cooling drop amount ΔT ₂ , and the water cooling temperature drop amount ΔT _bi for each bank of Equation (4). ) To the set values of the secondary plunger bank setting unit 38 and the primary and secondary plunger bank setting units 37 and 38 for setting the secondary plunger through the secondary plunger banks B9 to B14. follow A water injection control unit 39 is provided to cool the rolled plate by substantially controlling the water supply amounts of the first and second feed forward banks FFB1 and FFB2 and the feedback bank FBB. Preferably, the intermediate thermometer 20 has a structure as shown in FIG. 7, and is mounted on the ROT device as shown in FIG. 8.

As such, the ROT apparatus of FIG. 6 measures the intermediate temperature MT of the rolled plate and more precisely controls the amount of water supplied to the first and second feed forward banks FFB1 and FFB2. The intermediate temperature (MT) is kept constant so that the winding temperature (CT) is also kept constant.

7 is a view showing the temperature change of the rolled plate according to the temperature control device of the hot rolling of the present invention.

In Fig. 7, as in Fig. 4, 590DP steel is used as an example of the steel grade. FDT is the filament rolling side temperature, MT is the intermediate temperature, LT is the cold winding temperature, and CT is the hot winding temperature, respectively.

7, not only the finishing rolling exit temperature FDT but also the intermediate temperature MT are uniformly controlled. It can be seen that the low temperature winding temperature (LT) is also uniform by the intermediate temperature (MT).

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be apparent to those skilled in the art.

The temperature control apparatus and method of hot rolling of the present invention as described above measure the intermediate temperature, and use this to more precisely control the amount of water feed in the feed forward bank and feedback bank, in particular the feed forward bank. As a result, the winding temperature is always uniform so that the material of the rolled sheet is also constant.

Claims (5)

Correcting the learning coefficients of previously worked coils; Collecting the finishing rolling exit temperature, the winding temperature, the intermediate temperature and the rolling plate movement speed; Calculating an air cooling fall amount using the filament rolling exit temperature, and calculating a water cooling fall amount using the air cooling fall amount and a winding temperature target value; Calculating a primary water cooling amount according to the water cooling amount and the intermediate temperature target value, and setting a main water amount of each of the first banks according to the first water cooling amount; And Calculating a secondary water cooling amount by using the water cooling amount and the collected intermediate temperature, and setting a main water amount of each of the second banks according to the secondary water cooling amount. The method of claim 1, The air cooling drop amount is

Operation according to the following equation, The water cooling drop amount is calculated by subtracting the winding temperature target value from the air cooling drop amount, The first water cooling amount is calculated by subtracting the intermediate temperature target value from the water cooling amount, The secondary water cooling drop is calculated by subtracting the winding temperature target value from the collected intermediate temperature, The amount of water cooling of each of the banks is

Operation according to the following equation, B is FDT × a + b, FDT is the finishing machine normal rolling exit temperature, a, b, A is the coefficient, L is the length of the ROT apparatus, H is the thickness of the rolled plate. V is the moving speed of the rolled plate, the length of each of the L _b bank, C is the specific heat, ρ is the specific gravity, Q _i represents the heat flux coefficient of the i-bank, respectively. A learning coefficient corrector for correcting a learning coefficient of a previously worked coil; A performance data collection unit for collecting the finishing rolling exit temperature, the winding temperature, the intermediate temperature, and the rolling plate movement speed; An intermediate target temperature setting unit for setting an intermediate temperature target value; After calculating the air-cooled drop amount using the filament rolling exit temperature and calculating the water-cooled drop amount using the air-cooled drop amount and the coiling temperature target value, the first water cooling drop amount is calculated according to the water-cooled drop amount and the intermediate temperature target value, and the water-cooled drop amount and A water-cooled drop amount calculating unit configured to calculate a second water-cooled drop amount using the collected intermediate temperature; A first main water bank setting unit configured to set a main water amount of each of the first banks according to the first water cooling drop amount; A second main water bank setting unit configured to set a main water amount of each of the second banks according to the second water cooling drop amount; And And a water injection control unit for controlling the water supply amount of the first and second water injection banks according to a setting result of the first water injection bank setting unit and the second water injection bank setting unit. The method of claim 3, wherein the operation unit An air-cooled drop amount calculating unit configured to calculate the air-cooled drop amount; Calculating the first water cooling drop amount and a first water cooling drop amount calculating unit; And And a second water cooling fall amount calculation unit configured to calculate the second water cooling fall amount. The method of claim 3, The air cooling drop amount is

To be calculated according to The water cooling drop amount is calculated by subtracting the winding temperature target value from the air cooling drop amount, The first water cooling amount is calculated by subtracting the intermediate temperature target value from the water cooling amount, The secondary water cooling fall amount is calculated by subtracting the winding temperature target value from the intermediate temperature, The amount of water cooling of each of the banks is

Operation according to the following equation, B is FDT × a + b, FDT is the finishing machine rolling exit temperature, a, b, A is the coefficient, L is the length of the ROT apparatus, H is the thickness of the rolled plate. V is the moving speed of the rolling plate, the length of each of the L _b bank, C is the specific heat, ρ is the specific gravity, Q _i represents the heat flux coefficient of the i-bank, respectively.

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