JPS6127446B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating control method and apparatus for a continuous heating furnace.

A continuous heating furnace is used to heat a steel billet to a predetermined temperature required in a hot rolling process before manufacturing steel plates, sections, etc. in the hot rolling process.

Continuous heating furnaces include two-zone types with a preheating zone and heating zone, and three-zone types with a preheating zone, heating zone, and soaking zone. Figure 1 shows the conventional three-zone type furnace. something is shown.

In the figure, the object to be heated has three heating zones 10.
It sequentially passes through a (preparation zone), 10b (heating zone), and 10c (soaking zone) from upstream to downstream, is heated to a predetermined temperature, is extracted at a constant speed, and is sent to the next rolling process. The preheating zone 10a is a section for preheating the object to be heated guided into the furnace, the heating zone 10b is a section for sufficiently heating the object to be heated that has passed through the preheating zone 10a, and the soaking zone 10c is a section for preheating the object to be heated that has passed through the preheating zone 10a. This is a section that equalizes the temperature of the object to be heated that has passed through it.

Each of the heating zones 10a, 10b, and 10c is provided with a heating control device, but only the heating control device of the heating zone 10a will be described here as a representative.

In order to perform heating in the heating zone 10a, fuel and air are supplied from a fuel pipe 12a and an air pipe 14a, respectively, and the atmospheric temperature of the object to be heated rises due to combustion of the fuel supplied from the fuel pipe 12a. The object to be heated is heated. The flow rates of fuel and air are detected by the fuel flow heater 16a and the air flow detector 18a, and the fuel flow rate detector 1
The detection signal 100a of 6a is sent to the air ratio setter 20a and the fuel flow rate indicator 21a, and the air flow rate detector 18
The detection signals 102a of a are respectively supplied to the air conditioners 22a. The air ratio setting device 20a can supply the air flow rate command 104a according to the fuel flow rate to the air conditioner 22a based on the detection signal 100a, and the air conditioner 22a can supply the air flow rate command 104 according to the fuel flow rate.
a. The air valve 24a can be controlled by the detection signal 102a to make the air flow rate correspond to the fuel flow rate.

The actual temperature of the object to be heated heated in the heating zone 10a is detected by a thermocouple 26a, converted to an actual temperature detection signal 106a by an actual temperature detection signal converter 27a, and a heating temperature command 108a is supplied from a heating temperature command circuit 28a. The temperature control circuit 30a is supplied with the temperature control circuit 30a. This heating temperature command 108a corresponds to the heating target temperature of the heated object in each heating zone 10a, and the temperature control circuit 30a obtains the heating temperature signal 110a from the difference between the actual temperature detection signal 106a and the heating temperature command 108a, and controls the valve. output to the device 32a. The valve controller 32a receives the heating temperature control signal 110a.
The fuel valve 34a is driven and controlled, and as a result, fuel is supplied into the furnace in an amount corresponding to the target heating temperature of the object to be heated.

The heating control devices in heating zones 10b and 10c are the same as that in heating zone 10a, and their explanation will be omitted.

The conventional device shown in FIG. 1 has the above configuration, and its operation will be explained below.

In this conventional device, the object to be heated is in each heating zone 10.
A, 10b, and 10c are heated to their respective heating target temperatures independently of each other, and their temperatures are controlled. That is, each heating zone 10a,
10b, 10c, each zone 10a, 10
b, 10c heating temperature commands 108a, 108b,
an amount of fuel corresponding to 108c is introduced into the furnace;
Air corresponding to this fuel flow rate is introduced into the furnace.
As a result, in each zone 10a, 10b, 10c, the heated object receives heating temperature commands 108a, 108.
It is heated to each heating target temperature corresponding to b and 108c.

The heated object is extracted from the furnace at a predetermined speed and conveyed to the next hot rolling device.

However, in the conventional continuous heating furnace described above, when the size of the object to be heated changes, each heating zone 1
There is a drawback that the temperature of the heated object sent out from 0a, 10b, and 10c cannot be accurately controlled, and the actual temperature of the heated object finally extracted from the furnace cannot be accurately set to the heating target temperature. Ta. In other words, in the conventional apparatus shown in FIG. 1, it is assumed that the size of the object to be heated varies within a predetermined range, and if the object to be heated introduced into the furnace is too large, the conveyance speed is constant and the object to be heated is There was a problem in that the object was sent out before it was heated to each heating target temperature, and conversely, if the object to be heated was too small, it would be extracted in an overheated state. For this purpose, conventionally, the operator takes the size of the heated object into consideration and adjusts the conveyance speed to determine the extraction interval, that is, the preceding heated object and the following heated object are sent out of the furnace one after another. changing the extraction interval time, or heating temperature commands 108a, 108b,
108c was adjusted so that the extraction temperature of the object to be heated became the target temperature. However, since such measures are performed directly by the operator, temperature control cannot be performed with high precision and quickly, and when changing the conveyance speed of the heated object, problems may occur in the next rolling process. , etc., occur.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to accurately target the temperature of the heated objects extracted from the furnace even when the sizes of the heated objects introduced into the furnace are different. It is an object of the present invention to provide a temperature control method and device for a continuous heating furnace that can achieve a temperature of .

In order to achieve the above object, the method of the present invention detects the actual temperature of a moving object to be heated, and compares the actual temperature of the object to be heated with a heating temperature command corresponding to the target heating temperature of the object to be heated. In a heating control method for a continuous heating furnace, in which temperature deviation is detected by the temperature deviation, and heating control is performed for each heating zone to heat the object to be heated to a heating target temperature based on the temperature deviation, one of the extraction intervals of the object to be heated and The apparatus of the present invention detects the actual temperature of a moving object to be heated. a heating temperature command circuit that commands a heating target temperature of the heated object; a temperature control circuit that detects a temperature deviation from the actual temperature detection signal and the heating temperature command and outputs a heating temperature control signal; In a heating control device for a continuous heating furnace, which is provided for each heating zone and uses each heating temperature control signal to set the temperature of the heated object in each heating zone to the heating target temperature of each heating object, the extraction interval of the heated object is controlled. An extraction interval detection circuit is provided to detect the extraction interval, and the temperature control circuit of at least one heating zone outputs a heating temperature correction command by multiplying the extraction interval detection signal by the circuit deviation signal of the temperature control circuit of the next heating zone. The heating temperature command correction circuit is characterized in that it includes a command circuit and a heating temperature command correction circuit that corrects the heating temperature command using a heating temperature correction command.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 2 shows a continuous heating furnace to which the present invention is applied, and the same members as those in FIG.

The characteristic feature of this embodiment is that the extraction interval of the heated object extracted from the furnace is detected, and the detected extraction interval detection signal 112 and the downstream heating zone 10
Heating temperature control signals 110b, 110 of b, 10c
This multiplication result 114a, 1
14b to correct the heating temperature commands 108a, 108b of the heating zones 10a, 10b.

That is, in the figure, the continuous heating furnace is provided with a charging door to the left of the residual zone 10a to isolate the heating furnace from the outside air, and an extraction door is provided to the right of the soaking zone 10c. . Therefore, the heating furnace is isolated from the outside air between the two doors, and the object to be heated receives a well-controlled heating action within the furnace. When the object to be heated is placed in the furnace, the charging door is first opened and the object to be heated is inserted securely into the furnace, and then this charging door is closed, and each heating zone 10a, 10b, 10
The heating effect is carried out through c. When the object to be heated is taken out of the furnace, the extraction door is opened and the extraction door is closed after the object to be heated is reliably extracted out of the furnace.

Therefore, in the present invention, the above-mentioned extraction time, that is, the extraction interval, which is the time interval at which the preceding heated object and the following heated object are sequentially sent out of the furnace, that is, extracted, is determined by measuring the operating interval of the extraction door. You can know by.

In the figure, an extraction interval detection circuit 36 is provided for outputting an extraction interval detection signal 112 corresponding to the extraction interval of the object to be heated. Extraction interval detection circuit 3
6 is provided with an integrator 38, and a switch 40 is inserted into the feedback circuit of the integrator 38, which is turned on and off during the non-extraction time of the heated object and during extraction.
Therefore, the integrator 38 can detect the extraction interval time based on the on time of the switch 40. That is, as mentioned above, the time during which the extraction door (not shown) is closed approximately indicates the time interval during which the heating object is extracted from the heating furnace, and when this extraction door is closed, that is, during the non-extraction time, The switch 40 is on, and during this time the integrator 38
continues the integral operation, so the integral output is proportional to the extraction interval. Therefore, from the magnitude of this integrated output, it is possible to electrically detect the extraction interval, that is, the interval at which each object to be heated is taken out from the furnace. The integral output of the integrator 38 drives the motor 42 and determines the position of the sliding contact of the sliding resistor (potentiometer) 44, which corresponds to the extraction interval of the heated object determined by the position of the sliding contact. An extraction interval detection signal 112 is output from the extraction interval detection circuit 36.

Next, the extraction interval detection signal 112 is the heating temperature control signal 110b, 110c of the downstream heating zone 10.
are supplied respectively to heating temperature correction commands 114a and 11.
4b, an upstream correction command circuit 46a,
46b.

Temperature control signals 110b and 110c supplied to correction command circuits 46a and 46b, respectively, are supplied to proportional integrators 48a and 48b having predetermined dead zones,
After being integrated, it is supplied to multipliers 50a and 50b. Note that the proportional integrators 48a and 48b have a dead zone because minute noise is caused by the temperature control signals 110b and 48b.
110c, this is to prevent the temperature control circuits 30a and 30b from responding too sensitively to this noise. In each multiplier 50a, 50b, the extraction interval detection signal 112 and the proportional integrator 48a
and the extraction interval detection signal 112 and the output of the proportional integrator 48b are respectively performed.
The multiplication results of each multiplier 50a, 50b are sent to the limiter 5.
Heating temperature correction command 114 via 2a, 52b
a, 114b. In addition, Limita 5
2a, 52b heating temperature correction command 114a, 114
This is provided to remove abnormal values included in b.

Heating temperature correction commands 114a and 114b are supplied with heating temperature commands 108a and 108b, respectively, and adder/subtractors 54a and 54 constitute a heating temperature command correction circuit.
b, and each adder/subtractor 54a, 54b
are the heating temperature correction command 114a and the heating temperature command 1.
The heating temperature commands 108a and 108b can be corrected by adding and subtracting the heating temperature correction command 114b and the heating temperature command 108b, respectively.

The addition/subtraction of the adders/subtractors 54a, 54b is performed using polarity discrimination circuits 56a, 56b.
This is performed only when the polarity discrimination signals 116a, 116b are supplied from. Polarity discrimination circuit 56
heating temperature signals 110a and 110a and 56b, respectively.
0b and heating temperature control signals 110b and 110c are supplied, and the polarity discrimination circuits 56a and 56b are
The polarity determination signals 116a, 116b can be output only when the heating temperature control signals 110 supplied to each are both positive or negative. Therefore, the heating temperature commands 108a and 108b are corrected in the upstream heating zone 10 only when both the upstream heating zone 10 and the downstream heating zone 10 are underheated or overheated.

Heating temperature command 118 for adder/subtractor 54a, 54b
a, 118b are compared with actual temperature detection signals 106a, 106b, respectively, in arithmetic circuits 58a, 58b, and heating temperature control signals 110a, 110b are output from arithmetic circuits 58a, 58b.
The temperature control circuit 30c used is the same as that of the conventional device shown in FIG.

The apparatus of the embodiment shown in FIG. 2 has the above-mentioned structure, and its operation will be explained below.

In this embodiment, each heating zone 10a, 10b,
The temperature control of the object to be heated in 10c is performed using heating temperature control signals 110a, 110b, and 110c in the same manner as in the conventional apparatus described above.

However, in this embodiment, each heating zone 10
Heating temperature control signal 110a at a, 10b,
110b is a heating temperature correction command 114a, 114
The heating temperature commands 118a, 118b obtained by correcting the heating temperature commands 108a, 108b using b are compared with the actual temperature detection signals 106a, 106b.

The heating temperature correction commands 114a, 114b are the heating temperature control signals 110b, 1 of the downstream heating zone 10.
10c, when there is insufficient heating in the downstream heating zone 10, the heating in the upstream heating zones 10a and 10b is intensified in advance,
If there is excessive heating in the downstream heating zones 10b, 10c, the upstream heating is weakened in advance. Therefore, a heated object heated to a temperature that can be supported by the downstream heating zones 10b, 10c is introduced into the downstream heating zones 10b, 10c.
The heating zones 10b and 10c can heat the object to be heated to the target heating temperature.

Further, the heating temperature correction commands 114a and 114b are obtained based on the extraction interval detection signal 112,
In addition, the extraction interval of the object to be heated is determined according to the heating capacity of the furnace, so that it increases as the size of the object to be heated increases.
Since the object is inserted into the furnace and extracted from the furnace in such a manner that the object becomes smaller as the object becomes smaller, the extraction interval signal 112 corresponds to the size of the object to be heated. Therefore, when the heating temperature commands 108a and 108b are corrected by the heating temperature correction commands 114a and 114b based on the extraction interval signal 112, the heating of the heated object in the upstream heating zones 10a and 10b is as follows. When the size of the object to be heated is large, that is, when the extraction interval is long, the intensity is increased, and conversely, when the size of the object to be heated is small, that is, when the extraction interval is short, it is weakened. As a result, the object to be heated is heated in each heating zone 10 according to the size of the object to be heated.

In addition, as mentioned above, the heating temperature commands 108a, 10
8b is corrected by the polarity discrimination circuits 56a and 5.
This is only when the polarity discrimination signals 116a and 116b are output from the terminal 6b. That is, the heating temperature commands 108a and 108b are corrected only when the previous heating zone 10 and the next heating zone 10 are both underheated or overheated. This applies to the previous heating zone 10 only when the effect of underheating or overheating in the previous heating zone 10 cannot be absorbed by the heating control of the next heating zone 10.
This is to correct the heating temperature commands 108a, 108b, and prevent zone correction of the heating temperature commands 108a, 108b in other cases.

As explained above, according to this embodiment, the object to be heated extracted from the furnace can be accurately and automatically heated to the target temperature regardless of the size of the object to be heated.

Further, according to this embodiment, since the conveying speed of the heated object can be kept constant, there is no problem in the next rolling process.

FIG. 3 shows the results of temperature measurement of the object to be heated extracted by the embodiment apparatus shown in FIG. 2 and the conventional apparatus shown in FIG. 1, both of which have a target heating temperature of 1260 degrees. In the figure, the horizontal axis shows the order of temperature measurement of the heated object, and the vertical axis shows the temperature of the heated object. A shows the case of this embodiment, and B shows the case of the conventional device shown in FIG. There is. In addition, the length of the object to be heated is constant at 7 m, and its moving speed is constant. The 1st, 4th, and 7th temperature measurements are made using a 250 mm x 00 mm square bar, and the 2nd, 5th, and 8th temperature measurements are made using a 240 mm square bar. The 3rd, 6th, and 9th temperature measurements were performed on a 250 mm x 250 mm square bar.

As is clear from FIG. 3, according to the present invention, the extraction temperature of the object to be heated can be heated to a temperature extremely close to the target heating temperature (1260°), regardless of the size of the object.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional continuous heating furnace, Fig. 2 is a block diagram of a preferred embodiment of the present invention, and Fig. 3 is a block diagram of a conventional continuous heating furnace.
FIG. 2 is a graph diagram comparing actual temperature measurement results of the heated object extracted by the conventional device and FIG. 2 by the embodiment device. DESCRIPTION OF SYMBOLS 10... Heating zone, 26... Thermocouple, 28... Heating temperature command circuit, 30... Temperature control circuit, 36... Extraction interval detection circuit, 46... Correction command circuit, 54... Adder/subtractor, 56... Polarity discrimination circuit.

Claims (1)

[Claims] 1. Detecting the actual temperature of a moving object to be heated, and comparing the actual temperature of the object to a heating temperature command corresponding to a target heating temperature of the object to detect a temperature deviation. , in a heating control method for a continuous heating furnace that performs heating control for each heating zone to heat the object to a heating target temperature based on the temperature deviation, the extraction interval of the object to be heated and the temperature deviation of one of the heating zones 1. A heating control method for a continuous heating furnace, characterized in that the multiplication result is used to correct a heating temperature command for an upstream heating zone. 2. An actual temperature detector that detects the actual temperature of the moving heated object, a heating temperature command circuit that commands the heating target temperature of the heated object, and a heating temperature command circuit that detects a temperature deviation from the actual temperature detection signal and the heating temperature command and performs heating. A continuous heating furnace having a temperature control circuit for outputting a temperature control signal in each heating zone, and using each heating temperature control signal to adjust the temperature of the heated object in each heating zone to the heating target temperature of each heating element. The heating control device is provided with an extraction interval detection circuit for detecting the extraction interval of the object to be heated, and the temperature control circuit of at least one heating zone detects the extraction interval detection signal and the temperature deviation signal of the temperature control circuit of the next heating zone. 1. A temperature control device for a continuous heating furnace, comprising: a correction command circuit that outputs a heating temperature correction command by multiplying the heating temperature by the heating temperature correction command; and a heating temperature command correction circuit that corrects the heating temperature command by the heating temperature correction command.