JP2000054032A - Device for controlling combustion for annealing furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for composition for an annealing furnace which provides a means accurately controlling the transition of sheet temp. near the welded point at the time of executing a continuous annealing treatment, even in the case of developing the time lag in the change of the furnace temp. SOLUTION: In the control device of the combustion for the annealing furnace provided with a sheet temp. predicting model 106 which simulates the sheet temp. transition in the continuous annealing furnace 102 for removing the residual stress by continuously heating, holding and cooling the sheet having different specifications of target sheet temp., sheet thickness, etc., a furnace temp. command calculating part 107 which calculate the necessary furnace temp. command to control the sheet temp. at the outlet side of the furnace 102 with the model 106, and a controlling part 104 which controls the furnace 102 based on the furnace temp. command, an evaluating index deciding part 109 which calculates a value of the evaluating index for quantitatively evaluating the sheet temp. distribution at the outlet side near the changing point of the specification based on a product specifications of the target sheet temp., the precedence of the sheet before and after changing point of the specification, etc., by using the model 106 and the calculated furnace temp. command, and a command charging timing optimization part 108 which calculates the furnace temp. command changing timing for optimizing the value of the evaluating index and outputs to a control part 104, are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an annealing furnace combustion control apparatus in a steel plant, and more particularly to a method for accurately controlling a sheet temperature change in the vicinity of a welding point when continuously welding sheets having different specifications. The present invention relates to combustion control means for controlling.

[0002]

2. Description of the Related Art In a continuous annealing furnace in a rolling process, after finishing rolling, a sheet material having different specifications is welded into one sheet material, and a continuous heating, heat-retaining, and cooling treatment is performed to remove residual stress and obtain a uniform composition. This is a plant for producing a plate having components. The control target in the continuous annealing furnace is to make the sheet temperature on the outlet side of a plurality of furnaces correspond to the respective target temperatures corresponding to the sheet materials having different specifications, in order to set the outlet side sheet temperature to a desired value, Set the furnace temperature. Generally, in order to continuously perform an annealing process by welding plates having different specifications such as a plate thickness and a target temperature, the furnace temperature command value is changed in accordance with a change in the specifications.

However, since there is a time lag in the furnace temperature change with respect to the change of the furnace temperature command, if the furnace temperature command is changed at the time when the welding point reaches the furnace, many parts before and after the welding point do not satisfy the target plate temperature. Occurs. Considering such a phenomenon,
It is necessary to set the change timing of the furnace temperature command so as to maximize the yield near the welding point.

Conventionally, the furnace temperature command change timing has been calculated by, for example, Equation (1). In Equation 1, tm
Is the time required to achieve the set furnace temperature for new materials, Qnow
Is the current heat input, Qloss is the heat loss, Qout
Is the amount of heat required for heating the current material, and Qin is the amount of heat required for heating, that is, Qin = (next furnace temperature−current furnace temperature) · constant.

[0005]

(Equation 1)

In equation (1), when the furnace temperature command is changed, the amount of heat is supplied by a constant multiple (1 ± 0.25, ie, + 25% for heating, and -0.25% for cooling) of the currently supplied heat. Assuming that, the time tm required to realize the set furnace temperature of the new material is calculated. Using the time tm calculated in this manner, a furnace temperature command calculated in advance for the new material is sent to the furnace temperature control system at a command change timing that is earlier than the time when the new material reaches the furnace by the time tm.

[0007]

In the above conventional method,
Focusing on the current heat input, the next time the furnace temperature rises, heating is performed, and if the furnace temperature decreases, the furnace heat command is set based on a rough index that assumes that the heat input is multiplied by a fixed number in the direction of cooling. The change timing is calculated. However, actually, the amount of heat consumed by the furnace temperature control executed in response to the command differs depending on the target sheet temperature and the sheet thickness, and does not become a fixed multiple of the current input heat amount. For this reason, the change timing of the furnace temperature command calculated by the conventional method does not become an appropriate value that predicts a change in the sheet temperature.

Therefore, when the furnace temperature command is changed at the timing of changing the furnace temperature command calculated by the conventional method,
Problems such as the plate being heated more than necessary or the occurrence of a portion below the target plate temperature occurred.

On the other hand, Japanese Unexamined Patent Publication No. Hei 3 (1999) discloses a method of predicting a change in sheet temperature using a sheet temperature model and calculating an appropriate change timing.
In the technology of 277723 or Japanese Patent Application Laid-Open No. 4-323325, in order to minimize an error from a value obtained by adding an allowable error to a target sheet temperature, that is, a sheet temperature tolerance of an outlet sheet temperature near a welding point, the sheet temperature is reduced. Weighting the distance value and the integrated value before and after the welding point in consideration of the priority of the plate, with respect to the distance value and the integrated value of the error between the position deviated from the sheet temperature tolerance and the welding point, and the sum of them Was required to minimize the change timing. However, the sheet temperature tolerance before and after the welding point, the target sheet temperature,
The weight is determined by a simple comparison of the plate thickness, and in these simple comparisons, a material to which a large amount of heating is to be given priority is not selected as a priority material, and the weight is not appropriately set. As a result, especially in the case of a material in which the amount of heating should be given a high priority, the yield near the welding point did not improve so much.

An object of the present invention is to provide an annealing apparatus having a means for accurately controlling a change in sheet temperature in the vicinity of a welding point during continuous annealing even if there is a time lag in a change in furnace temperature with respect to a change in a furnace temperature command. It is to provide a furnace combustion control device.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention removes residual stress by continuously heating, keeping or cooling plates having different specifications such as target plate temperature and plate thickness. Sheet temperature prediction model that simulates sheet temperature transition in continuous annealing furnace, and furnace temperature command calculation that calculates the furnace temperature command required to control the outlet sheet temperature of the continuous annealing furnace with a time lag in the furnace temperature change using the sheet temperature prediction model Unit, and a control unit for controlling the continuous annealing furnace based on the furnace temperature command, in the furnace combustion control device, using the plate temperature prediction model and the calculated furnace temperature command, the target sheet temperature and before and after the specification change point Evaluation index determination unit that calculates the evaluation index value that quantitatively evaluates the outlet sheet temperature distribution near the specification change point based on product specifications such as plate priority, and furnace temperature command change that optimizes the evaluation index value Calculate timing and output to controller Suggest furnace combustion control apparatus provided with a decree changing timing optimization unit.

The evaluation index calculated by the evaluation index determining unit is a sum of values obtained by multiplying the integrated value of the deviation from the target value of the outlet plate temperature before and after the specification change point by a weighting coefficient within a predetermined section from the specification change point. It can be.

The weighting factor can be a function of the furnace temperature command for the plates before and after the specification change point.

It is desirable that the weight coefficient of the plate having the larger furnace temperature command among the furnace temperature commands for the plates before and after the specification change point is larger than the weight coefficient of the plate having the smaller furnace temperature command.

In any case, the weighting coefficient is a positive or negative function of the integrated value of the deviation of the outlet plate temperature from the target value. When the integrated value is negative, the weighting coefficient is larger than the absolute value when the integrated value is positive. Weight coefficient.

The evaluation index is an index that changes in a direction to lower the evaluation when the maximum value of the sheet temperature at the specification change point is larger than a predetermined value in consideration of the cooling performance of the part where the sheet is cooled in the continuous annealing furnace. It is.

Further, the control unit for controlling the continuous annealing furnace includes:
A furnace temperature feedback unit that controls the furnace temperature and the furnace temperature command to match based on the furnace temperature command and the furnace temperature command change timing, and controls the outlet sheet temperature of the continuous annealing furnace to match the target sheet temperature. The section from the point at which the furnace temperature command for specification change is executed based on the command change timing to the point at which the specification change point reaches the outlet of the continuous annealing furnace is a section other than the section for switching to control by the furnace temperature feedback section. May include control system switching means for switching to control by the sheet temperature feedback unit.

There is provided a model correction unit for correcting the sheet temperature prediction model so as to eliminate the deviation between the outlet plate temperature and the sheet temperature calculated by the sheet temperature prediction model, and the furnace temperature command calculation unit corrects the temperature by the model correction unit. After completion, the furnace temperature commands are calculated in order from the closest to a plurality of plates reaching the subsequent annealing furnace, and the command change timing optimization unit calculates the furnace temperature command change timing after the correction by the model correction unit is completed. You may do so.

A steady state determining unit for detecting whether or not the continuous annealing furnace is in a steady state is provided, and the model correcting unit performs various conditions such as furnace temperature, sheet temperature, and sheet thickness when the continuous annealing furnace is in a steady state. It is also possible to take the amount and modify the plate temperature prediction model.

In the present invention, the priority of the sheet is determined according to the set furnace temperatures of the respective materials before and after the welding point calculated using the sheet temperature model to achieve the target sheet temperature. As a result, a material having a higher set furnace temperature is prioritized in accordance with a large amount of heating, and a general annealing specification in which a material having a large amount of heating is prioritized is satisfied, thereby enabling continuous annealing with a good yield. .

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of an annealing furnace combustion control apparatus according to the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram showing the configuration of an embodiment of an annealing furnace combustion control device according to the present invention. The annealing furnace combustion control device 101 includes a command calculation unit 103, a feedback control unit 104, a model correction unit 105, and a steady state determination unit 1011.

The command calculation unit 103 calculates a furnace temperature command for each furnace zone to satisfy the target plate temperature and a change timing of the furnace temperature command accompanying a change in material specifications, and the feedback control unit 1.
04. The feedback control unit 104 captures the furnace temperature detected by the continuous annealing furnace 102 and executes the feedback control for controlling the gas flow rate so as to realize the furnace temperature command in accordance with the given furnace temperature command change timing. The feedback control unit 104 also takes in the exit side sheet temperature from the continuous annealing furnace 102 to eliminate the sheet temperature error that could not be avoided even by the control based on the furnace temperature command, and also performs a follow-up control for achieving the target sheet temperature. I do.

The steady state determining unit 1011 determines whether the plate temperature and the furnace temperature are in a steady state.

When it is determined that the plate temperature and the furnace temperature are in the steady state, the model correction unit 105 fetches various state quantities such as the furnace temperature, the plate temperature, and the plate thickness at that time, and sets the plate temperature in the command calculation unit 103. The temperature prediction model 106 is corrected so as to eliminate the difference in transition between the model 106 and the actual phenomenon.

The command calculation unit 103 is provided with the sheet temperature prediction model 10
6, a furnace temperature command calculation unit 107, a command change timing optimization unit 108, an evaluation index determination unit 109, and an operation schedule storage unit 1010. Furnace temperature command calculator 10
7 calculates a furnace temperature command necessary for realizing the target sheet temperature, using the sheet temperature prediction model 106 for estimating the sheet temperature transition. The evaluation index determination unit 109 determines an index for quantitatively evaluating the change in the sheet temperature near the welding point in consideration of required specifications such as the degree of achievement of the target sheet temperature and the priority of the material. Further, based on this index, using the sheet temperature prediction model 106, the sheet temperature change near the welding point when the furnace temperature command calculated by the furnace temperature command calculation unit 107 is executed at a certain change timing is predicted, An evaluation value of the change timing of the furnace temperature command is calculated.
The operation schedule storage unit 1010 stores parameter values for determining the above-described evaluation index at each welding point in the order of materials processed according to the operation schedule, and upon receiving a request from the evaluation index determination unit 109, stores these parameter values in the evaluation index determination. Send it to the unit 109. The command change timing optimizing unit 108 updates the furnace temperature command change timing by an optimization technique such as the steepest descent method with reference to the evaluation of the furnace temperature command change timing by the evaluation index determining unit 109, and Is calculated.

FIG. 2 shows a continuous annealing furnace 1 to which the present invention is applied.
It is a schematic diagram which shows the typical structure of the combustion part (Heating Section) of No. 02. The continuous annealing furnace 102 has three furnaces (Zone 1).
To 3), and a furnace temperature sensor 204 is provided for each furnace. The sheet temperature sensors 202 and 203 are provided on the entrance side of Zone 1 and on the exit side of Zone 3, respectively, and detect the temperature of the entrance side plate to the furnace and the temperature of the exit side plate from the furnace. The combustion gas is circulated in the radiant tube 201 to heat the inside of the furnace to a uniform temperature, and the plate is heated by radiant heat from the radiant tube 201. Generally, a target plate temperature at each zone exit is given, and the gas flow rate is controlled so as to achieve the target temperature.

FIG. 3 is a block diagram showing an example of the configuration of the sheet temperature prediction model 106. The sheet temperature prediction model 106 is
It comprises a sheet temperature model 301 and a furnace temperature dynamic model 302. The sheet temperature model 301 is based on a given furnace temperature, sheet thickness,
The transition of the sheet temperature from the furnace inlet to the furnace outlet is predicted based on various conditions such as the passing speed. The heat transfer from the furnace to the plate in the radiant tube heating furnace is performed by the radiant tube 20.
The radiant heat Q from 1 is dominant and is given by Equation 2. The heat transfer inside the plate is described by the heat conduction equation of Equation 3. However, φcg is called the overall heat absorption coefficient,
Generally, the heat transfer coefficient is determined by the shape of the furnace. Also,
x is the distance in the plate thickness direction, T is the furnace temperature, θ is the plate temperature (inside), θs
Is the sheet temperature (surface), c is the specific heat, ρ is the specific gravity, and k is the heat transfer coefficient. The sheet temperature is calculated by converting Equation 3 into a differential equation and solving Equation 4 as a boundary condition.

[0029]

(Equation 2)

[0030]

(Equation 3)

[0031]

(Equation 4)

FIG. 4 is a block diagram showing an example of the configuration of the furnace temperature dynamic model 302. The furnace temperature dynamic model 302 is a model that simulates a dynamic furnace temperature transition when the furnace temperature control is executed based on a given furnace temperature command. C1 and Cf are controllers, and are constants or constants. It is described by a transfer function.

The furnace temperature model is given by, for example, a first-order lag equation as shown in Expression 5. Since the effect of the plate inserted into the furnace can be reflected in the time constant T in Equation 5, using the actual data,
The relationship between the heat content per unit volume of the plate to be inserted and T is established in advance, and T is determined using these relationships.

[0034]

(Equation 5)

The furnace temperature command calculation unit 107 uses the sheet temperature model 301 when obtaining a furnace temperature command for satisfying the target sheet temperature. Although details will be described later, the outlet plate temperature for an appropriate furnace temperature command is calculated by the plate temperature model 301, and the process of changing the furnace temperature command is repeated based on the result, thereby obtaining a furnace temperature command that satisfies the target plate temperature. .

On the other hand, the evaluation index determining unit 109 predicts a sheet temperature transition under a furnace temperature dynamically changed near the welded portion due to the furnace temperature command change in order to calculate an optimum furnace temperature command change timing. For this purpose, a desired sheet temperature transition is determined using the furnace temperature dynamic model 302 and the sheet temperature model 301. That is, the furnace temperature command and the furnace temperature command change timing are given to the furnace temperature dynamic model 302, the furnace temperature change according to these values is predicted, and the welding is performed by the sheet temperature model 301 based on the obtained furnace temperature transition. Calculate the outlet sheet temperature before and after the part.

FIG. 5 is a flowchart showing the processing procedure of the furnace temperature command calculation unit 107. Furnace temperature command calculator 107
Solves the inverse problem by using a sheet temperature model 301 that calculates an outlet temperature for a given furnace temperature in order to calculate a furnace temperature command that realizes a target sheet temperature (θout *) for each zone outlet. .
In this embodiment, a procedure for solving the inverse problem using the Newton-Raphson method will be described.

In step 41, the target plate temperature θout * is fetched. In step 42, various state quantities such as a material, a plate thickness, and an assumed entrance plate temperature corresponding to the plate having the taken target plate temperature θout * are taken. In step 43, a preset initial value T0 of the furnace temperature is fetched. In step 44, T0 is substituted for the trial point T. In step 45, the furnace exit side sheet temperature θout is set to θout = f (T), and the sheet temperature differential value f ′ (T) at the trial point T is calculated. That is, T and T + Δ
T (ΔT: minute increment of T set in advance), the taken θout * and various state quantities are sent to the plate temperature model 301, and f
(T) and f (T + ΔT) are obtained, and f ′
(T) is calculated. In step 46, a linear first-order approximation formula at T is constructed using the differential information obtained in step 45, and T is updated with the intersection of this first-order approximation formula and θout * = 0 as the next value. At this time, T is updated by Expression 7. In step 47, the end is determined by the mathematical expression 8 using the updated T. If Equation 8 is satisfied, T
As a furnace temperature command to the feedback control unit 104,
If not, the process returns to step 45. The above processing is executed for all Zones.

[0039]

(Equation 6)

[0040]

(Equation 7)

[0041]

(Equation 8)

FIG. 6 is a block diagram showing an example of the configuration of the evaluation index determining section 109. The evaluation index determination unit 109
It comprises a sheet temperature error calculation section 501 and an evaluation section 502. The sheet temperature error calculating section 501 refers to the sheet temperature prediction model 106 to obtain various sheet temperature errors used for calculating an evaluation value of the time tm necessary for realizing the set furnace temperature in the evaluation section 502, and evaluates the evaluation section 502. To supply. The evaluation unit 502 constructs an index for evaluating the value of the furnace temperature command change timing tm sent from the command change timing optimization unit 108, and calculates the evaluation value.

FIG. 7 shows the furnace temperature and output when the furnace temperature command is changed at a time required to realize the set furnace temperature from the time of arrival at the furnace inlet at the welding point, that is, at the time when the furnace temperature command change timing tm is traced back. It is a figure showing an example of a situation of change of a side board temperature. The hatched portion is a deviation (temperature error) from the target plate temperature.

The evaluation value F (t) of tm constructed by the evaluation unit 502
m) is given by Equation 9. E1 and E2 are integral values of the temperature error before and after the welding point, respectively.
Given by 1.

[0045]

(Equation 9)

[0046]

(Equation 10)

[0047]

[Equation 11]

Ef (i) and Ee (i) are i × dt from the welding point.
(dt: about a few minutes in a minute time set in advance) is a temperature error at a time that is separated before and after each time. n is E
f (i) (or Ee (i)) <εt (εt: threshold value set in advance) or an appropriate fixed value. Weighting factor s
1 and s2 are values determined according to the quality of the material such as the target plate temperature and plate thickness before and after the welding point, and are stored in the operation schedule storage unit 1010.

The sheet temperature error calculating section 501 sends the furnace temperature command, the time tm, and various state quantities at that time taken from the furnace temperature command calculating section 107 and the command change timing optimizing section 108 to the sheet temperature predicting model 106, respectively. , The sheet temperature before and after the welding point calculated by the sheet temperature prediction model 106 is received. Next, Ef (i), Ee (i), and E1,
E2 is obtained, and E1 and E2 are sent to the evaluation unit 502. Evaluation unit 5
02 is an evaluation value F based on E1 and E2 based on the weighting coefficients s1 and s2 fetched from the operation schedule storage unit 1010.
(tm) is calculated and sent to the command change timing optimizing unit 108.

In the continuous annealing furnace 102, the plate is cooled after burning. In order to avoid the temperature rise exceeding the cooling capacity here, a method of calculating the evaluation value with the maximum value θmax of the sheet temperature at the welding point as an evaluation target is also conceivable. That is, when θmax exceeds the threshold value θth previously calculated based on the cooling capacity, an algorithm is adopted that does not adopt the time tm, or a penalty function based on θmax is incorporated in Expression 9. Equation 12 shows the evaluation value F (tm) at this time.

[0051]

(Equation 12)

On the other hand, the evaluation of the sheet temperature transition may differ depending on whether the sheet temperature is higher or lower than the target sheet temperature. Due to the nature of the annealing treatment, it is often preferable to exceed the target sheet temperature. Therefore, E1 and E2 are calculated by Expressions 13 and 14, and E1 and E2 are calculated.
A method is also conceivable in which the weighting coefficients s1 and s2 in Equation 9 are changed as in Equation 15 according to the sign of E1, E2. b1 and b2 are
It is one or more positive constants.

[0053]

(Equation 13)

[0054]

[Equation 14]

[0055]

(Equation 15)

FIG. 8 shows a command change timing optimizing unit 10.
8 is a flowchart illustrating an example of the processing procedure of FIG. The command change timing optimizing unit 108 uses the steepest descent method, which is an optimization technique, as an example, in order to find the time tm that minimizes the evaluation value F [tm].

In step 71, an initial value t [0] = 0 of the trial point for calculating the time tm is set. In step 72, i = 0. In step 73, t [i] and t [i]
[i] + Δt (Δt: minute time set in advance, about one minute) is sent to the evaluation index determination unit 109. In step 74, t
The evaluation values F (t [i]) and F (t [i] + Δt) calculated by the evaluation index determination unit 109 for [i] and t [i] + Δt are fetched. In step 75, t [i] is updated by Expression 16. In step 76, convergence is determined by equation (17). In Expression 17, ε is a preset threshold value. If the condition is satisfied, the process proceeds to step 77; otherwise, i is increased by 1 and the process returns to step 73. In step 77, t [i] is calculated as the furnace temperature command change timing tm, and is sent to the feedback control unit 104.

[0058]

(Equation 16)

[0059]

[Equation 17]

The calculated furnace temperature command and the furnace temperature command change timing tm are calculated by the feedback controller 10 after the calculation is completed.
4 and the control based on the command value is immediately executed. In addition, the furnace temperature command and the time tm for each material are obtained in advance according to the operation schedule and stored in a table by offline processing. A mode in which the furnace temperature command and the time tm corresponding to the flowing plate are sent to the feedback control unit 104 with reference to this is also conceivable.

FIG. 9 shows an operation schedule storage unit 1010.
3 is a table showing the configuration of FIG. Operation schedule storage unit 10
Numeral 10 has a database structure, and in the order of processing to be executed according to the operation schedule, information of the plate (for example, plate No., plate thickness, target plate temperature) and weighting coefficients s1, s2 of Equation 9 at each welding point. Are stored. Depending on the target plate temperature and the thickness of the plate before and after the welding point, the priorities of the plates are different between the front and the rear, and the weight coefficient s is determined according to the priorities.
1, s2 are set. The ease of heating is determined by the material and the thickness of the plate. In an annealing treatment in which overheating is generally preferred over unheating, a material that is difficult to heat is given priority. In the example of FIG. 7, the sheet thickness of the rear member and the target sheet temperature both increase with respect to the front member. For this reason, the weight coefficient s2 of the rear member is set to a value larger than s1 in order to avoid the transition of the sheet temperature of the rear member, which tends to increase the number of unheated portions, as much as possible. Weighting factor s
1, s2 is based on the index, in addition to the method manually set by the user, focuses on the furnace temperature commands before and after the weld as a measure of the difficulty of heating, the weight coefficient of the material with a large furnace temperature command value furnace The temperature command value is set to be larger than that of the material having a small temperature command value.
It is also conceivable that the setting is made automatically by Expression 19.
Here, T1 and T2 are a furnace temperature command for the front material and a furnace temperature command for the rear material, respectively, and Tmax is the larger value of T1 and T2.

[0062]

(Equation 18)

[0063]

[Equation 19]

FIG. 10 is a block diagram showing an example of the configuration of the feedback control unit 104. The feedback control unit 104 includes a command switching unit 901, a furnace temperature feedback control unit 902, and a sheet temperature feedback control unit 90.
3 and a control system switching unit 904. In the command switching unit 901, the furnace temperature command fetched from the furnace temperature command calculation unit 107 is preceded by the furnace temperature command change timing tm fetched from the command change timing optimization unit 108 before the arrival time of the welding part on the furnace entrance side, The temperature is sent to the furnace temperature feedback control unit 902. Furnace temperature feedback control unit 90
2 is a furnace temperature sensor 2 that satisfies a given furnace temperature command.
The furnace temperature detected from the furnace 04 is taken in, and a gas flow rate, which is an operation amount, is sent to the radiant tube 201. The control system switching unit 904 activates the sheet temperature feedback control unit 903 at the timing when the new material reaches the furnace outlet. The sheet temperature feedback control unit 903 changes the furnace temperature command in a direction to reduce the difference between the outlet sheet temperature detected by the sheet temperature sensor 203 and the target sheet temperature, and causes the outlet sheet temperature to follow the target temperature.

FIG. 11 shows a furnace temperature feedback control unit 90.
2 is a block diagram illustrating an example of a configuration of a sheet temperature feedback control unit 903. FIG. C1, C2, and C3 are controllers that are designed for a control target identified by an ARMA model or the like and are described by constants or transfer functions. The switching control by the control system switching unit 904 is a problem that occurs when both control systems are simultaneously activated, that is, the furnace temperature feedback control unit 902 and the front material which operate to realize the furnace temperature for the rear material before reaching the furnace entrance of the welded part. In order to avoid interference with the sheet temperature feedback control unit 903 that works to achieve the target sheet temperature for the welding, when the sheet temperature feedback control unit 903 is activated after the welding section reaches the furnace temperature outlet, this problem is completely solved. Can be resolved.

FIG. 12 is a system diagram showing an example of the configuration of the model correction unit 105. The model correction unit 105 corrects the sheet temperature model 301 in a direction to decrease δθout from an error (δθout) between the detected sheet temperature and the sheet temperature calculated by the sheet temperature model 301. In the present embodiment, an example using a neural network will be described as a method of realizing this correction procedure. The model errors are collected into φcg in Equation 2 which is likely to change due to aging or the like, and this is selected as a tuning target.
In this embodiment, it is assumed that φcg is constant in zones 1 to 3.
The model correction unit 105 constituted by a neural network sends a δθout, φcg, entry side plate temperature, passing plate speed, zone 1 furnace temperature, zone 2 furnace temperature, zone 3 furnace temperature, plate The thickness and the correction amount (Δφcg) of φcg are calculated.

In the neural network of the model correcting unit 105, neurons 1101 are connected in layers by synapses 1102. Input to the input layer 1103 is Ii
If the output of the intermediate layer 1104 is Mj, Ii and Mj
Is given as, for example, Expression 20, Expression 21, and Expression 22. Wij (j is the number of hidden neurons)
Is the weight given to the synapse 1102 connecting the i-th input neuron and the j-th hidden neuron, θ
j is a constant corresponding to neuron j.

[0068]

(Equation 20)

[0069]

(Equation 21)

[0070]

(Equation 22)

Although a differentiable monotone saturation function is generally used as f (uj), a sigmoid function as shown in Expression 21 is generally used. Further, the M thus obtained
When j is used, the output O of the neuron in the output layer 1105 is represented by Expressions 23, 24, and 25. Vj
Is a weight connecting the j-th intermediate layer neuron and the output layer neuron, and θ is a constant corresponding to the output layer neuron.

[0072]

(Equation 23)

[0073]

(Equation 24)

[0074]

(Equation 25)

The model correction unit 105 calculates the output O corresponding to the input Ii as described above. Model correction unit 105
Is constructed as follows. First, the relationship between Δθout and the φcg correction amount (Δφcg) for various state quantities at this time is established in advance using the sheet temperature model 301. That is, φ
The output sheet temperature for cg and φcg + Δφcg is set to the sheet temperature model 30.
According to 1, the process of obtaining θout and θout + δθout is executed a plurality of times while changing Δφcg, and a relationship between Δθout and Δφcg is constructed. Next, by supplying the constructed relationship between δθout and Δφcg as a teacher signal to the neural network of FIG. 12 and learning it, the model correcting unit 105 can be constructed.

For details of the learning method, see, for example, the magazine “Natur
e] Vol.323. No.9. (David E. Rumelhart. Geoffrey E.
Hinton & Ronald J. Williams. "Learning Representa
tionsby Back-Propagating Error. "Pages 533 to 536
P. Oct. 1986).

The steady state judging unit 1011 includes the model correcting unit 10
In order to extract the exit sheet temperature necessary for correcting the sheet temperature model 301 and the transition of various state quantities received by the part that has detected the exit sheet temperature, a determination process 5 is performed for selecting a steady state. The reason why the steady state is selected is that the state quantity is small and the state is easy to extract. As a criterion for determining a steady state, attention is paid to the variance of the outlet sheet temperature, and when the outlet sheet temperature satisfies Expression 26, the state is regarded as a steady state. here,
{θout} l is the current outlet plate temperature, ε is a threshold value, and n is a constant.

[0078]

(Equation 26)

Subsequently, based on the passing speed, various state quantities such as the outlet sheet temperature and the corresponding furnace temperature and inlet sheet temperature at this time are extracted from a database storing the rolling results and sent to the model correcting section 105. . Since the sheet temperature prediction model 106 corrected by the model correction unit 105 is a model reflecting the current plant characteristics, various commands are calculated again using this model. That is, upon receiving the steady state determination by the steady state determination unit 1011, the model correction unit 105
Then, at the timing when the correction of the sheet temperature prediction model 106 is completed, a process of obtaining a furnace temperature command and a furnace temperature command change timing for new materials from the current time onward is executed in order from the latest.

[0080]

According to the present invention, an index for quantitatively evaluating the sheet temperature distribution near the welding point is provided based on the required product specifications, and a furnace temperature command for maximizing this index (evaluation function). An annealing furnace combustion control device capable of calculating the change timing and accurately controlling the transition of the sheet temperature near the welding point is obtained, and the yield of products in the annealing furnace is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an annealing furnace combustion control device according to the present invention.

FIG. 2 is a combustion section of a continuous annealing furnace 102 to which the present invention is applied.
It is a schematic diagram which shows the typical structure of (Heating Section).

FIG. 3 is a block diagram illustrating an example of a configuration of a sheet temperature prediction model 106.

FIG. 4 is a block diagram illustrating an example of a configuration of a furnace temperature dynamic model 302.

FIG. 5 is a flowchart showing a processing procedure of a furnace temperature command calculation unit 107.

FIG. 6 is a block diagram illustrating an example of a configuration of an evaluation index determination unit 109.

FIG. 7 shows an example of a change in the furnace temperature and the outlet plate temperature when the furnace temperature command is changed at a point in time when the time required for realizing the set furnace temperature has been traced from the arrival time at the furnace inlet at the welding point. FIG.

FIG. 8 is a flowchart illustrating an example of a processing procedure of a command change timing optimization unit;

FIG. 9 is a table showing a configuration of an operation schedule storage unit 1010.

FIG. 10 is a block diagram illustrating an example of a configuration of a feedback control unit 104.

FIG. 11 is a block diagram illustrating an example of a configuration of a furnace temperature feedback control unit 902 and a sheet temperature feedback control unit 903.

FIG. 12 is a system diagram showing an example of a configuration of a model correction unit 105.

[Explanation of symbols]

 Reference Signs List 101 Annealing furnace combustion control device 102 Continuous annealing furnace 103 Command calculation unit 104 Feedback control unit 105 Model correction unit 106 Sheet temperature prediction model 107 Furnace temperature command calculation unit 108 Command change timing optimization unit 109 Evaluation index determination unit 201 Radiant tube 202 input Side sheet temperature sensor 203 Outlet sheet temperature sensor 204 Furnace temperature sensor 301 Sheet temperature model 302 Furnace temperature dynamic model 501 Sheet temperature error calculating section 502 Evaluation section 901 Command switching section 902 Furnace temperature feedback control section 903 Sheet temperature feedback control section 904 Control system switching Unit 1010 Operation schedule storage unit 1011 Steady state determination unit 1101 Neuron 1102 Synapse 1103 Input layer 1104 Middle layer 1105 Output layer

Continued on the front page (72) Inventor Yasuo Morooka 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside the Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Jira Kumayama 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture F term in Hitachi Ltd. Omika factory (reference) 4K038 AA01 BA01 CA01 DA01 DA02 DA03 EA01 EA02 EA03 FA03 4K043 AA01 BB04 CA02 DA05 EA04 FA03 FA04 FA07 FA12 GA10

Claims (9)

[Claims] 1. A sheet temperature prediction model simulating a sheet temperature transition in a continuous annealing furnace in which sheets having different specifications such as a target sheet temperature and a sheet thickness are continuously heated or kept or cooled to remove residual stress, A furnace temperature command calculation unit that calculates a furnace temperature command required for controlling the outlet sheet temperature of the continuous annealing furnace having a time lag in the furnace temperature change by the sheet temperature prediction model, and the continuous annealing furnace based on the furnace temperature command. An annealing furnace combustion control device including a control unit for controlling, based on product specifications such as a target sheet temperature and a sheet priority before and after a specification change point using the sheet temperature prediction model and the calculated furnace temperature command. An evaluation index determination unit that calculates a value of an evaluation index for quantitatively evaluating the outlet sheet temperature distribution near the specification change point; and calculates a furnace temperature command change timing for optimizing the value of the evaluation index and outputs the timing to the control unit. Command change timing Annealing furnace combustion control apparatus characterized by comprising a optimization unit. 2. The annealing furnace combustion control device according to claim 1, wherein the evaluation index calculated by the evaluation index determining unit is an outlet sheet temperature before and after the specification change point within a predetermined section from the specification change point. Characterized in that it is a sum of values obtained by multiplying the integrated value of the deviation from the target value by a weighting coefficient. 3. The annealing furnace combustion control device according to claim 2, wherein the weighting factor is a function of the furnace temperature command for plates before and after the specification change point. 4. The annealing furnace combustion control device according to claim 2, wherein the weight coefficient of a plate having a larger furnace temperature command among the furnace temperature commands of the plates before and after the specification change point is smaller. An annealing furnace combustion control device, wherein the weight coefficient is larger than the weight coefficient of a plate having a temperature command. 5. The annealing furnace combustion control device according to claim 2, wherein the weighting coefficient is a positive / negative function of an integrated value of a deviation of the outlet plate temperature from a target value, An annealing furnace combustion control device, wherein the weighting coefficient is a larger absolute value when the integrated value is negative than when the integrated value is positive. 6. The annealing furnace combustion control device according to claim 2, wherein the evaluation index is such that a maximum value of a sheet temperature at the specification change point controls cooling of the sheet in the continuous annealing furnace. An annealing furnace combustion control device characterized by being an index that changes in a direction to decrease the evaluation when the value is larger than a predetermined value in consideration of the cooling performance of a part to be performed. 7. The annealing furnace combustion control device according to claim 1, wherein a control unit that controls the continuous annealing furnace is configured to perform control based on the furnace temperature command and the furnace temperature command change timing. A furnace temperature feedback unit that controls the furnace temperature and the furnace temperature command to match, a sheet temperature feedback unit that controls the output side sheet temperature of the continuous annealing furnace to match the target sheet temperature, The section from the point at which the furnace temperature command for specification change is executed based on the command change timing to the point at which the specification change point reaches the outlet of the continuous annealing furnace is switched to control by the furnace temperature feedback unit, and the sheet temperature is switched except for the section. 2. The continuous annealing furnace control device according to claim 1, further comprising control system switching means for switching to control by a feedback unit. 8. The annealing control apparatus according to claim 1, wherein the deviation between the outlet sheet temperature and the sheet temperature calculated by the sheet temperature prediction model is eliminated. Providing a model correction unit for correcting the sheet temperature prediction model, the furnace temperature command calculation unit, after the completion of the correction by the model correction unit, the furnace sequentially from the nearest to a plurality of plates reaching the continuous annealing furnace thereafter A continuous annealing furnace combustion control device, which is a means for calculating a temperature command, wherein the command change timing optimizing unit is a means for calculating the furnace temperature command change timing after the correction by the model correcting unit is completed. 9. The annealing furnace combustion control device according to claim 8, further comprising: a steady state determining unit that detects whether the continuous annealing furnace is in a steady state, wherein the model correcting unit determines that the continuous annealing furnace is in a steady state. A continuous annealing furnace combustion control device, wherein various state quantities such as furnace temperature, sheet temperature, sheet thickness and the like are taken in a steady state to correct the sheet temperature prediction model.