JPH07238324A - Method and apparatus for continuously executing heat treatment to metallic strip - Google Patents

Abstract

PURPOSE:To provide a method and an apparatus for novel continuous heat treatment to a metallic strip in which the eccentricity is corrected by detecting the eccentric quantity of the metallic strip indirectly from gas temp. difference in the strip width direction of jetting gas in a gas jet device. CONSTITUTION:The eccentricity of the metallic strip S from the center of carrying passage is informed indirectly from the temp. distribution of the medium gas blown from a wind box 3 arranged so as to face to the surface of the metallic strip S and divided into few zones in the width direction. By this method, the strip passing positional adjusting device 14 for metallic strip S of a steering roll 12, etc., is operated to adjust the strip passing position and thus, the eccentricity of the metallic strip S is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous heat treatment method and apparatus for metal strips, and more particularly, to an eccentric amount of a metal strip with respect to a conveying path when the metal strip is continuously heated or cooled by using a gas jet device. This is indirectly obtained from the gas temperature distribution state of the gas jet device.

[0002]

2. Description of the Related Art As one of heating or cooling methods in a metal strip manufacturing process, a gas jet heating or cooling method in which a high-speed heating or cooling gas is blown to the metal strip is performed. When heating or cooling the metal strip, it is important in terms of quality to perform it uniformly in the width direction of the metal strip, and uneven heating or cooling causes uneven properties of the steel sheet and defective shapes.
The case of gas jet heating or cooling is no exception, and heating or cooling as uniform as possible is required.

For example, as to the gas jet cooling of the metal strip in the annealing cooling process of the cold rolled steel sheet, Japanese Patent Publication No. 63-1
No. 4052, Japanese Examined Patent Publication No. 5-27691, etc., the cooling zone is divided into zones in the width direction for uniform cooling in the strip width direction, and the blowing gas flow rate is controlled in each zone to control the strip width direction. There have been proposed means such as controlling the cooling temperature.

For example, in the case of the above Japanese Patent Publication No. 63-14052, in cooling the strip S which is a metal strip in a continuous annealing furnace, as shown in FIG. There is used a gas jet device in which upper and lower wind boxes 3 are arranged so as to face the surface of the strip S. Each air box 3 is divided into a plurality in the strip width direction of the strip S, and each divided zone is equipped with a gas flow rate control valve (damper), and the cooling gas is blown onto the surface of the strip S from each of these zones. I put it on and let it cool down. In that case, as a plate thermometer for detecting the temperature distribution of the strip S in the plate width direction, for example, a plurality of scanning thermometers 4 are arranged alternately with each wind box 3 along the traveling direction of the strip S.

Then, the temperature signal from the plate thermometer 4 is used to calculate a temperature difference ΔT in the plate width direction with respect to the average temperature of the strip S in the plate width direction by a plate temperature control calculation device, and the temperature difference ΔT is within an allowable limit. When it exceeds, the position in the plate width direction is detected, and the temperature difference is kept within the allowable limit by controlling the gas flow rate control valve in the zone corresponding to the detected position and controlling the amount of cooling gas blown out from the corresponding zone. The temperature of the strip S in the plate width direction is made uniform to prevent the occurrence of defective shapes.

In this case, when the temperature difference ΔT exceeds the permissible limit in the positive direction, that is, when a high temperature portion exceeds the permissible limit, a predetermined flow rate control valve is opened to cool the temperature difference ΔT. In the negative direction, that is, when there is a low temperature part that exceeds the allowable limit, the opening / closing of the flow control valve corresponding to the low temperature position is first detected, and if it is open, the flow control valve is controlled to be throttled and closed. If so, the other flow rate control valves are opened appropriately so that the temperature difference ΔT is within the allowable limit.

In general, when cooling control is performed by such zone division, the state of air flow distribution of the blowing gas air flow for each zone is made symmetrical with respect to the line center.
Since the edge portion of the strip S is cooled more easily than the central portion, the temperature distribution in the plate width direction has a mountain-shaped symmetrical distribution with the edge portion lowered. Further, in the case of Japanese Examined Patent Publication No. 5-27691, the gas jet header (wind box) in the gas jet cooling of the continuous annealing furnace is divided into two in the strip width direction,
Further, the division position is changed for each header of each stage, and a right side gas supply device that supplies gas to all the headers on the right side of the division position and a left side gas supply device that supplies gas to all the headers on the left side of the division position. And control the amount of gas supplied by the gas supply devices on both the left and right sides by the arithmetic and control unit based on the strip temperature distribution plate temperature distribution measured by the plate thermometer that measures the plate temperature in the strip width direction. By smoothly changing the air flow distribution of the cooling gas, the balance of the temperature profile in the plate width direction is smoothly adjusted.

However, in the gas jet cooling of the strip in the cooling zone of the continuous annealing furnace of the actual cold-rolled steel sheet manufacturing line, even if the air volume of the medium gas is adjusted so as to be symmetrical, it is always possible. It is not always possible to cool symmetrically with respect to the line center. For example, now, as shown in FIG. 10, in the case where a plurality of air boxes (cooling plenum chambers) 3 are provided in the cooling zone 1 of the annealing furnace in the plate width direction of the strip S via partition walls 2, Left chamber 3 of wind box 3
Consider a state in which the strip S is eccentric to the left in the figure with respect to the line center when the cooling medium gas is blown from A and the right chamber 3C with the same air flow rate.

Then, the left side wall 1L of the cooling zone 1 and the wind box 3
In the left chamber 3A, the amount of radiation heat from the strip S increases and the temperature rises. On the other hand, in the right side wall 1R and the right chamber 3C, on the contrary, the amount of radiant heat received from the strip S decreases, and the temperature drops. As a result, the temperature of the strip S decreases on the right side, and the temperature of the right side wall 1R and the right chamber 3C further decreases, which is repeated.

Further, since the cooling medium gas blown from the cooling chamber 3 is heated in the wind box 3, the temperature of the blown gas changes according to the amount of heat received by each chamber of the wind box 3,
In the case of the drawing, hot gas is blown out from the left chamber 3 and cold gas is blown out from the right chamber 3C. Therefore, if the strip S is left uncorrected without correcting the eccentricity, the temperature difference between the left and right of the strip S increases,
Eventually, the quality of the strip S such as a defective shape and a flaw is caused. Therefore, the control of the eccentricity of the strip S is a serious problem from the viewpoint of quality maintenance.

Further, if the eccentricity is significant, there may occur inconveniences such as collision with the inner plate of the annealing furnace to cause breakage.
As described above, in heat treatment such as continuous annealing of the strip S, the eccentricity of the strip S from the center of the transport path is reduced to the strip S.
Since it adversely affects the uniformization of the temperature distribution in the strip width direction, it is important for continuous heat treatment of the strip S to constantly monitor the presence or absence of eccentricity of the strip S.

However, especially in a high temperature continuous annealing furnace or the like, it is extremely difficult to monitor the eccentricity of the strip S in the furnace because of the heat resistance of the equipment used. Conventional in-furnace CPC (Center Position Cont
The roll is typically one that detects the presence or absence of eccentricity of the strip S by a measuring nozzle method. This is to follow the strip edge with a sensor, and the sensor has an injection nozzle and a pressure receiving nozzle, and the pressure received by the pressure receiving nozzle changes depending on whether or not the edge of the strip blocks between the nozzles. This nozzle is installed so as to sandwich both ends of the strip, the positions of both ends are detected, and the center position is obtained from this. However, this edge detection nozzle method has drawbacks such as a large device, difficult calibration, and high cost.

Therefore, recently, a system using an industrial television has come into use. This one is equipped with a viewing window on the furnace wall, and two left and right edges of the strip S are monitored from the outside of the furnace by two surveillance TV cameras through the glass, and the obtained image is converted into an electric signal and then processed. To detect the strip edge and control the steering roll so that the left and right edge positions are balanced.

[0014]

However, in the conventional eccentricity control in the continuous heat treatment of the metal strip using the surveillance camera from the outside of the furnace, when the glass of the viewing window becomes cloudy, the edge of the metal strip in the furnace is fogged. There is a problem in that the position cannot be discriminated and therefore eccentricity control becomes impossible. Also,
If the installation accuracy of the monitoring camera is insufficient, the metal strip center line by the monitoring camera and the original transfer center line of the heat treatment equipment will not match, so uneven heating or cooling will be performed while performing eccentricity control. There is also a problem.

Therefore, the present invention has been made by paying attention to such a conventional problem, and in the plate width direction of the gas blown out from the wind box (chamber) of the gas jet apparatus without monitoring from the outside of the furnace. SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel method and apparatus for continuously heat treating a metal strip by correcting the eccentricity by indirectly detecting the amount of eccentricity of the metal strip from the difference in gas temperature.

[0016]

In order to achieve the above object, the invention of a continuous heat treatment method for a metal strip according to claim 1 is arranged so as to face a plate surface of a continuously supplied metal strip in the width direction of the metal strip. When the heating or cooling medium gas is blown from the zone divided into zones to continuously heat treat the metal strip with a uniform temperature distribution in the width direction, the temperature of the medium gas blown from the zone is measured for each zone. It is characterized in that the temperature distribution state in the width direction is obtained, the eccentricity of the metal strip from the center of the transport path is obtained based on the temperature distribution state, and the plate passing position in the width direction of the metal strip is corrected.

The invention according to claim 2 is characterized in that, in claim 1, the passage of the metal strip is such that the temperature distribution state of the temperature of the medium gas blown out from the wind box is symmetrical with respect to the line center. It is characterized in that the plate position is corrected. Further, the invention of claim 3 is characterized in that, in claim 1 or 2, the passing position of the metal band is corrected by tilting of a steering roll which rotates in contact with the metal band.

The invention of a continuous heat treatment apparatus for a metal strip according to claim 4 has a wind box which is arranged so as to face the plate surface of the metal strip and is zone-divided in the width direction of the metal strip. A gas jet device that blows a heating or cooling medium gas onto the plate surface of the metal strip from the above, a thermometer that detects the temperature of the gas blown out from each zone of the wind box, and abutting on the plate surface of the metal strip to convey. Direction adjusting device having a steering roll capable of tilting while rotating in a direction and a tilting actuator thereof, and an eccentric amount from the transport path center of the metal strip calculated from a temperature detection signal of the thermometer and the calculation result. Accordingly, an eccentricity control calculation device that outputs an adjustment command for the tilting actuator to the steering roll device in a direction to reduce the amount of eccentricity is provided.

[0019]

The relationship between the deviation (eccentricity) of the metal strip from the center of the transport path during gas jet heating or cooling of the metal strip and the change in the temperature distribution state of the medium gas in the plate width direction will be discussed with reference to the drawings. First, an outline of a gas jet plate temperature control method, which is a premise of the eccentricity control of the metal strip of the present invention, will be described with reference to FIG.

Upper and lower air boxes 3, 3 are arranged in a cooling zone 1 of the annealing furnace, and each air box 3 has a plurality of (three in the figure) chambers 3A, 3B, 3C with partition walls 2 in the width direction. It is divided into zones. The strip S includes the upper and lower chambers 3
It is cooled by a medium gas (cooling gas in this case) 6 blown out at high speed from the nozzles 5 of A, 3B and 3C. The cooling gas 6 whose temperature has risen by heat exchange with the strip S is
After being cooled by the gas cooler 7, it is sent again to the wind box 3 by the circulation fan 8. The amount of air blown to each chamber 3A, 3B, 3C forming the zone of the wind box 3 is controlled by the damper 9.

FIG. 2 shows a mode of heat transfer performed between the strip S, the wind box 3 and the cooling gas 6 at this time. The cooling gas 6 sent to the wind box 3 is in the wind box 3. It is heated by the nozzle 5 and is blown from the nozzle 5 at the temperature T _Z , and is blown onto the strip S. On the other hand, the heat from the strip S is transferred to the wind box 3 mainly by radiation. When the amount of heat removed is Q _S , it is expressed as Q _S = α (T _S −T _Z ) (1).

Here, Q _{S is the} heat removal amount α: heat transfer coefficient T _S : strip temperature _TZ : cooling gas (blowing) temperature.

The heat quantity Q _{S that} is removed from the strip S and received by the wind box 3 is transferred to the cooling gas 6 inside the wind box through the wall of the wind box 3 (heat transfer quantity Q _C ). In a steady state, the amount of heat received by the wind box 3 from the strip S, Q _S, and the amount of heat transferred from the wind box 3, Q _C , to the cooling gas are equal. Therefore, the blowing temperature T _Z of the cooling gas 6 blown out from the nozzle 5 is
Heat quantity received windbox 3 receives from the strip _S Q S (= Q _C)
And the flow rate V _g of the cooling gas 6 are determined.

T _Z = f (Q _S , V _g ) (2) If the cooling gas flow rate V _g is constant, the blowout temperature T _Z may be determined by the heat reception amount Q _S of the wind box 3. Recognize. Now, for example, in FIG. 1, looking at the amount of heat received for each zone of the wind box 3, that is, the amount of heat received from the strip S for each chamber 3A, 3B, 3C, the chamber 3B at the center of the wind box 3 has the entire zone width. Across the strip S
Receives radiant heat from. However, chambers 3A at both ends
Since 3C and 3C have a part of the zone width deviated from the strip S, the heat receiving amount Q _S per unit width is smaller than that in the chamber 3B. Therefore, each chamber 3A, 3B, 3
When the same flow rate of the cooling gas 6 per unit width is passed through C (the same blowing speed from the nozzle 5), the blowing temperature T _Z
Is low in the chambers 3A and 3C on both sides, and the central chamber 3
B becomes higher.

Thus, the strip S is not eccentric
In the state, the plate temperature T of the strip S _SIs uniform in the width direction
(Left side temperature T of strip S_SL= Temperature T on the right side_SR)
If so, the blowing temperature T of the cooling gas 6_ZThe width of the
As for the cloth state, as shown in Figure 3,
The mountain shape is symmetrical with respect to the number 3B. Sanawa
The temperature T blown out from the left chamber 3A_ZLAnd right side
Blowout temperature T from chamber 3C_ZRIs equal to (T
_ZL= T_ZR), The difference ΔT_Z= 0.

On the other hand, the strip S is shown in FIG.
If the plate temperature T is eccentric to one of the transport paths,_SIs wide
Even if the direction is uniform, for example, the left chamber 3A of the wind box 3
The entire zone width becomes the radiant heat receiving area and the amount of heat received Q_S
On the contrary, the right side chamber 3C of the wind box 3 is the zone
Only a part of the width becomes the radiant heat receiving area and the amount of heat received Q_SIs reduced
Less. Therefore, the cooling gas in the eccentric state of the strip S is
Blowout temperature T of 6 _ZBlows from the left chamber 3A
Start temperature T_ZLIs blown out from the right side chamber 3C
Temperature T_ZRHigher temperature (T_ZL> T_ZR)become. sand
That is, the blowing temperature T of the cooling gas 6 from the nozzle 5_Zof
The distribution in the width direction is asymmetrical as shown in Fig. 4.
It

From this, when the plate temperature T _S of the strip S is uniform in the width direction, if the temperature distribution state of the medium gas in the wind box 3 arranged facing the plate surface of the strip S is known, It can be said that the presence or absence of eccentricity of the strip S from the center of the transport path can be indirectly known. From the above viewpoint,
In the present invention, the eccentricity control of the metal strip is performed by the eccentricity control arithmetic unit based on the temperature distribution state of the medium gas in the line width direction according to the control logic shown in the flowchart of FIG.

The steps will be described below. Step S1: The blowing temperature T _Z and the flow rate V _{g of} each chamber that divides the air box into a plurality of zones in the plate width direction and the plate temperature T _{S in} the width direction of the metal strip are detected and read. Step S2: A temperature distribution (for example, a temperature difference in the plate width direction with respect to an average temperature in the plate width direction) is calculated from the read plate temperature T _{S in} the width direction of the metal strip.

Step S3: Based on the calculation result of the plate temperature distribution, it is determined whether or not the plate temperature distribution is uniform. If the plate temperature distribution is not uniform, the process proceeds to step S4. On the other hand, if the plate temperature distribution is uniform, the process proceeds to step S5. Step S4: An adjustment command for the medium gas flow rate V _g of the wind box is output so that the plate temperature distribution becomes uniform, and the process returns to step S1.

Step S5: The difference (T _ZL -T _ZR = ΔT _Z ) between the blowing temperature T _ZL from the chamber at the left end of the wind box and the blowing temperature T _ZR from the chamber at the right end is obtained. Step S6: If the obtained value of ΔT _Z is 0, it is judged that the blowout temperature distribution is bilaterally symmetrical and that there is no eccentricity, and the process returns. On the other hand, if the value of ΔT _Z is not 0, it is judged that the blowout temperature distribution is asymmetrical and eccentric, and the process proceeds to the next step.

Step S7: The eccentricity amount is calculated based on the value of ΔT _Z by a map search stored in advance.
Alternatively, heat transfer calculation is performed based on Stefan-Boltzmann's law relating to radiative heat transfer, and the heat transfer rate corresponds to the ratio of the area of the strip S facing the chamber at the left end to the area of the strip S facing the chamber at the right end. From the relationship
It is also possible to calculate the amount of eccentricity of the strip S with respect to the value of ΔT _Z. Step S8: The steering angle of the steering roll required to correct the eccentricity is calculated based on the calculation result of the eccentricity amount of the metal band.

The steering angle correction value thus obtained is output to the DDC by the steering angle control device for the steering roll and the eccentricity of the strip S is corrected by tilting the steering roll in a predetermined direction by a predetermined angle. Thus, in the present invention, by detecting the medium gas blowing temperature distribution state in the width direction of the metal strip of the gas jet device,
The eccentricity of the metal strip is corrected based on the eccentricity information from the center of the transport path of the metal strip that is indirectly obtained from the state of the temperature distribution of the blowout.

Therefore, it is not necessary to use a surveillance camera.
Inconvenience such as improper eccentricity adjustment due to fogging of the monitoring window
Does not occur. It also blows all of the many chambers of the windbox.
The stripping temperature is obtained, and the result is the thickness of the metal strip in the strip and the strip.
Gold is checked against various data such as width, heat treatment temperature and strip speed.
Calculating the amount of eccentricity of a metal strip is based on
When applied to eccentricity control, the calculation load becomes large.
That is not always realistic. So the strip
In the central chamber at the center position of the S transport path in the width direction
Blowing from chambers at equal distances on the left and right sides
Temperature T_ZLAnd T_ZRAnd temperature difference ΔT _ZThere
If the strip S is eccentric, the difference ΔT
_Z= T_ZA-T _ZCThe strip S is connected so that
Large control load by controlling the plate position in the width direction
The eccentricity of the strip S can be corrected without
It

[0034]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 6 and FIG. 7 are schematic diagrams showing an outline of an apparatus configuration example for carrying out the method of the present invention. By controlling the blowing temperature of the cooling gas as the medium gas so as to be symmetrical in the plate width direction, It is an example of a gas jet type continuous heat treatment apparatus in which the strip passing position of the strip S is zero with respect to the center of the transport path.

That is, in the cooling zone 1 of the annealing furnace, a plurality of chambers 3A, 3B, 3 in which an air box (cooling chamber, only the upper side is shown in FIG. 7) 3 is divided by a partition wall 2 in the width direction.
It is provided with C. The strip S of metal strip is
It is cooled by the cooling gas 6 blown out from the nozzle of the wind box 3. A circulation fan 8 is provided in the path for taking out the cooling gas 6 whose temperature has risen due to heat exchange with the strip S from the inside of the cooling zone 1 via a common gas cooler 7 as a gas temperature adjusting device for cooling. The gas is sent out again to the wind box 3 via a damper 9 as an air volume adjusting device.
A gas flow meter (not shown) is arranged in each of the piping paths from the damper 9 to the chambers 3A, 3B, 3C of the wind box.

A thermocouple 10, which is a temperature measuring device for the cooling gas 6, is provided at each of the gas outlets of the chambers 3A, 3B and 3C of the wind box 3. Although not shown, for example, a scanning plate thermometer is provided in the cooling zone 1 as a plate thermometer for detecting the temperature distribution of the strip S in the plate width direction. Then, the temperature signal from the plate thermometer is used to calculate the temperature difference in the plate width direction with respect to the average temperature of the strip S in the plate width direction, and when the temperature difference exceeds a predetermined value, the position in the plate width direction is determined. It has a process computer (P / C) and a direct digital controller (DDC) as a plate temperature control arithmetic unit for detecting and adjusting a damper 9 for controlling the flow rate (air volume) of the medium gas to the chamber corresponding to this detection position. is doing.

Inside the cooling zone 1 (which may be outside), as shown in FIG. 7, a steering roll 12 that contacts the lower surface of the strip S and rotates in the transport direction, and actuators 13 for tilting the rolls at both ends thereof are provided. A plate passing position adjusting device 14 in which 13 is arranged is arranged. In this plate passing position adjusting device 14, the actuator 13 is a hydraulic cylinder, and pressure oil is applied to an oil inlet / outlet on a rod side and a head side with a piston of the hydraulic cylinder interposed therebetween via an electrohydraulic adjuster (not shown). It is being supplied.

Further, the eccentricity amount from the center of the transport path of the strip S is calculated based on the gas blowout temperature detection signal of the thermocouple 10 which is the temperature measuring device for the cooling gas 6, and the eccentricity amount adjustment command according to the calculation result is calculated. Has a P / C as an eccentricity control calculation device 15 for outputting the eccentricity to the DDC, and the DDC which has received the eccentricity amount adjustment command outputs the operation electric signals of the actuators 13, 13 of the threading position adjusting device 14 to the electrohydraulic pressure not shown It is designed to output to a formula controller. This operation signal is sent to the moving coil in the electro-hydraulic adjuster to operate it, and in response to this, the hydraulic injection pipe operates in a predetermined direction by a predetermined amount to perform electro-hydraulic conversion, and the hydraulic cylinder The piston rod of the actuator 13 composed of is driven by feedback based on a control signal from a position sensor (not shown), and the tilting operation of the steering roll 12 is performed.

The eccentricity control of the strip S of this embodiment is as follows.
The procedure is as follows. The cooling gas 6 sent to the wind box 3 via the damper 9 by the circulation fan 8 has a temperature T _Z from the nozzle.
And is blown onto the strip S. Gas blowing temperature T of each chamber 3A, 3B, 3C of the wind box
Measure _ZA , T _ZB and T _ZC with thermocouple 10 and read in P / C. At the same time, each chamber 3A, 3B, 3 of each wind box
The medium gas flow rate (air volume) V _g to C is also read.
Further, in order to detect the temperature distribution of the strip S in the plate width direction, the measured value of the plate temperature T _S from the plate thermometer installed at the position corresponding to each chamber 3A, 3B, 3C is also read. (Step 1).

With the read chambers 3A, 3B and 3C,
Plate temperature T at each corresponding position _SValue in the board width direction
Average plate temperature avT_SAnd the average plate temperature
Degree avT_SAnd each plate temperature T in the plate width direction_STemperature difference from
T_STo calculate the widthwise distribution of plate temperature (step
2). Temperature difference ΔT at each position_SWithin a certain value
It is possible to calculate the plate temperature in the width direction by calculating whether or not
It is determined whether or not the cloth is uniform (step 3).

If the temperature difference ΔT _{S at} any position exceeds a predetermined value, it is judged that the distribution of the plate temperature in the width direction is non-uniform,
A predetermined chamber target air volume required to make the plate temperature distribution state uniform is calculated, and the calculation result is output to the DDC as a flow rate (air volume) control signal of the medium gas to the chamber corresponding to the position in the plate width direction. Return to step 1. The DDC sets the opening degree of the damper 9 at the inlet of the chamber according to the target air volume and adjusts the air volume V _g .

As a result, the widthwise temperature distribution of the plate temperature is made uniform. If the temperature difference ΔT _S at each position does not exceed the predetermined value, the temperature distribution in the width direction is determined to be uniform, and the process proceeds to the following steps. Each chamber 3A, 3B read,
Based on the value of the blowing temperature T _Z for every 3 C, the difference between the blowing temperature T _ZL from the chamber at the left end and the blowing temperature T _ZR from the chamber at the right end (T _ZL −T _ZR = Δ
_TZ ) is calculated (step 5).

It is determined whether or not the value of the obtained temperature difference ΔT _Z is 0. If it is 0, the blowout temperature distribution is symmetrical and it is judged that the strip S has no eccentricity, and the process returns. On the other hand, if the value of the temperature difference ΔT _Z is not 0, it is judged that the blowout temperature distribution is laterally asymmetrical and eccentric, and the process proceeds to the next step (step S6). Based on the value of the above temperature difference ΔT _Z ,
The eccentric amount of the strip S is calculated by a map search stored in advance or by an arithmetic expression (step S
7).

Based on the calculation result of the eccentricity amount of the strip S, the steering angle of the steering roll 12 necessary for correcting the eccentricity is calculated (step S8). The steering angle correction value thus obtained is output to the DDC which is a steering angle control device for the steering roll 12, and the DDC receives the command signal to operate the roll tilt actuator 13 to move the steering roll 12 in a predetermined direction. The eccentricity of the strip S is corrected by tilting it by an angle.

FIG. 8 shows the experimental result of the eccentricity control of the strip S by the above procedure. Board thickness 0.7 m
m, a strip width 1200 mm, the gas is blown into each chamber 3A, 3B, 3C of the wind box 3 when the strip S is eccentric to the left of the line center and fed into the cooling zone 1 T _ZA , T _ZB , T _ZC is shown by a polygonal line X (the strip S has a uniform temperature distribution in the plate width direction). Due to the eccentricity, the amount of heat received from the strip S of the left chamber 3A becomes larger than that of the right chamber 3C, and as a result, the medium gas blowing temperature T _Z becomes a left-right asymmetric shape in which the left chamber 3A side is high and the right chamber 3C side is low, and the left and right blowing temperature difference is ΔT _Z = T _ZA −T _ZC was about 50 ° C.

From this state, the left and right chambers 3A, 3C are
The steering roll 1 of the plate passing position adjusting device 14 so that the difference ΔT _Z between the gas blowing temperatures T _ZA and T _ZC of
When 2 was tilted, a bilaterally symmetrical gas blowing temperature distribution state as shown by the broken line Y in FIG. 8 was obtained, and the center of the strip S almost coincided with the line center.

In the above description, the strip S is cooled, but the present invention is not limited to this.
Even when the heating gas is blown from the heating chamber to heat, the heat transfer direction is opposite to the cooling direction, and the same function as in the case of the cooling is performed. Further, the position control means for controlling the eccentricity of the strip S is not limited to the steering roll. Besides so-called intermediate guide roll type position control means using pinch rolls, ringer rolls, etc., so-called side guide type position control means using roller side guides or plate side guides can also be adopted. However, in contrast to the side guide system in which the position of the threading plate is mechanically fixed and controlled, the intermediate guide roll system is preferable because it has the advantage of being able to thread the strip S at high speed without damaging the ears.

[0048]

As described above, according to the first aspect of the present invention.
According to the method of the invention, the heating or cooling medium gas is blown out from the wind box zone-divided in the width direction so as to be opposed to the plate surface of the metal strip to continuously heat treat the metal strip. The blowout temperature is measured for each zone to determine the distribution state of the blowout temperature in the plate width direction, and based on the blowout temperature distribution state, the amount of eccentricity from the center of the transport path of the metal strip is indirectly obtained to determine the width direction of the metal strip. Since it corrects the passing position of the sheet, it is impossible to control due to the cloudiness of the window, as in the case of directly monitoring the presence or absence of eccentricity with a monitoring camera from the outside even in high temperature heat treatment. It is possible to achieve stable eccentricity control over a long period of time without causing any inconvenience.

Further, according to the method of the second aspect of the present invention, the passage position of the metal strip is set so that the temperature distribution in the width direction of the blowout temperature of the medium gas from the wind box is symmetrical with respect to the line center. Since it is corrected, it is only necessary to detect the blowout temperatures from the chambers at both ends of the wind box and control them so that they are almost the same, and the calculation load can be greatly reduced and eccentricity control with fast response is possible. Has the effect of becoming.

Further, according to the invention of claim 3 of the present invention,
Since the correction of the threading position of the metal strip is performed by the tilting of the steering roll that rotates in contact with the metal strip according to claim 1 or 2, the eccentricity can be corrected at high speed without fear of scratching the metal strip. Therefore, the product quality and yield can be improved. Further, according to the invention of the continuous heat treatment apparatus of the present invention,
As shown in FIG. 3, a heating or cooling medium gas is provided to the plate surface of the metal strip and has a wind box divided into zones in the width direction of the metal strip from each zone to the plate surface of the metal strip. It has a gas jet device for blowing, a thermometer for detecting the temperature of the gas blown out from each zone of the wind box, a steering roll which is in contact with the plate surface of the metal strip and can be tilted while rotating in the transport direction, and a tilting actuator thereof. A steering roll device and a temperature detection signal from a thermometer are used to calculate the amount of eccentricity of the metal strip from the center of the transport path, and the steering roll device is instructed to adjust the tilt actuator in a direction to reduce the amount of eccentricity according to the calculation result. Since it has an eccentricity control calculation device for outputting, an inexpensive gas thermometer can be used, and an expensive eccentricity measuring device such as a surveillance camera device can be used. In principal, and also the maintenance is easy, an effect that can be improved moreover productivity by reducing the cost.

In order to make the plate temperature distribution in the width direction of the metal strip uniform according to the eccentricity control of the present invention, instead of directly measuring the plate temperature with an expensive plate thermometer to obtain the plate temperature distribution, the wind box is used. If the plate temperature distribution is indirectly obtained by measuring the temperature of the medium gas blown out from the device, an inexpensive thermometer such as a thermocouple will suffice, and a significant cost reduction can be achieved. .

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a continuous annealing furnace cooling device to which a gas jet plate temperature control method of the present invention is applied.

FIG. 2 is a diagram illustrating a mode of heat transfer in FIG.

FIG. 3 is a diagram when the gas blowing temperature is in a symmetrical distribution state.

FIG. 4 is a diagram showing a case where a gas blowing temperature is in an asymmetric distribution state.

FIG. 5 is a basic flowchart of the continuous heat treatment method for metal strips of the present invention.

FIG. 6 is a schematic view of a heat treatment apparatus for carrying out the continuous heat treatment method for metal strips of the present invention.

FIG. 7 is a perspective view schematically showing the relationship between the device of FIG. 6 and the plate passing position adjusting device.

FIG. 8 is a graph showing the experimental results of the present invention.

FIG. 9 is a schematic view of a cooling zone of a conventional metal strip annealing furnace using a plate thermometer.

FIG. 10 is a schematic view of an apparatus for explaining one aspect of strip eccentricity in an annealing line.

[Explanation of symbols]

 1 (heating or) cooling zone 3 wind box 3A chamber 3B chamber 3C chamber 5 blowing nozzle 6 medium gas 7 gas temperature adjusting device 9 gas air volume adjusting device 10 thermometer (for blowing gas) 12 steering roll 13 actuator 14 passing plate position adjustment Device 15 Eccentricity control calculation device S Metal strip (strip)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takayuki Naoi 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama Prefecture (no address) Inside Mizushima Works, Kawasaki Steel Co., Ltd. (72) Takanori Kondo Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama 1-chome (without street number) Inside Kawashima Steel Co., Ltd. Mizushima Steel Works (72) Inventor Kosuke Kaname 1-chome (without street number) Mizushima Kawasaki Dori, Kurashiki City, Okayama Prefecture Kawasaki Steel Co., Ltd. within Mizushima Steel Works

Claims (4)

[Claims] 1. A heating or cooling medium gas is blown from a wind box, which is arranged so as to face a plate surface of a continuously supplied metal strip and is zone-divided in the width direction of the metal strip, to make the metal strip uniform in the width direction. When continuously heat-treating with a temperature distribution, the temperature of the medium gas blown out from the wind box is measured zone by zone to obtain the temperature distribution state of the medium gas in the width direction, and the metal strip transport path is based on the temperature distribution state. A continuous heat treatment method for a metal strip, characterized in that the amount of eccentricity from the center is obtained to correct the plate passing position in the width direction of the metal strip. 2. The sheet passing position of the metal strip according to claim 1, wherein the passage position of the metal strip is corrected so that a temperature distribution state of the temperature of the medium gas blown from the wind box in the width direction is symmetrical with respect to the line center. And a continuous heat treatment method for a metal strip. 3. The continuous heat treatment method for a metal strip according to claim 1, wherein the passing position of the metal strip is corrected by tilting a steering roll that rotates in contact with the metal strip. 4. A heating or cooling medium gas is provided to the plate surface of the metal strip and has a wind box divided into zones in the width direction of the metal strip, and heating or cooling medium gas is applied to the plate surface of the metal strip from each zone. A gas jet device for blowing, a thermometer for detecting the temperature of the gas blown out from each zone of the wind box, a steering roll which is in contact with the plate surface of the metal strip and is tiltable while rotating in the transport direction, and a tilting actuator thereof. And a steering roll device for calculating the amount of eccentricity of the metal strip from the center of the conveying path from the temperature detection signal of the thermometer and reducing the amount of eccentricity according to the calculation result. And an eccentricity control calculation device that outputs an adjustment command for the tilt actuator.