JPS5843454B2 - Crown control method in hearth roll of continuous annealing furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the thermal crown of a hearth roll used in a rigid furnace such as a continuous annealing furnace. It concerns how it can be adjusted.

For example, the outer surface of a plurality of hearth rolls installed in a vertical continuous annealing furnace is provided with a single crown as shown in Figure 1a or a narrow body crown as shown in Figure 1. Centering is performed in the width direction of the strip to be plated to prevent it from meandering.

The general tendency for strips to meander is that thick and narrow materials are more likely to meander, but in order to prevent such thick and narrow materials from meandering, a correspondingly high roll crown is required. It is necessary to attach it.

However, although rolls with a large amount of crown are effective for thick and narrow materials, the centering effect is too large for thin and wide materials because the roll crown is too large, and on the contrary, the squeezing phenomenon is more likely to occur. .

This narrowing of the strip is a phenomenon that occurs when the central part of the strip lifts up due to the transition of plates from both edge sides inward. Narrowing down becomes more likely to occur.

If such squeezing occurs, not only will the plate break and work efficiency drop, but the squeezed strip will not be usable as a finished product, resulting in a significant drop in yield.

From the above, the current hearth rolls in continuous annealing furnaces are operated with low roll crowns that do not cause this squeezing phenomenon, and the meandering of thick and narrow materials is sacrificed to some extent. I had no choice but to do it.

Furthermore, when considering the thermal crown that is formed inside the hearth roll of a continuous annealing furnace, the phenomena in the cooling chamber and heating chamber are completely opposite.

In other words, Figures 2a and b imply the roll surface temperature distribution of the hearth roll applied to the cooling chamber in the furnace and the occurrence of thermal crowns. Due to thermal expansion of the outer surface of the hearth roll R in contact with the strip S, a thermal crown T (shaded area) higher than the initial crown (2) is generated, and its temperature distribution also exhibits a mid-height shape as shown in figure a.

This increases the centering effect of the strip, but as described above, in the case of a thick and narrow strip, constriction is more likely to occur.

On the other hand, Figures 3a and 3b schematically show the roll surface temperature distribution of the no-throttle roll in the heating chamber in the furnace and the occurrence of thermal crown. Since the temperature is lower than the atmospheric temperature in the furnace, the outer surface of the hearth roll R in contact with the strip S is cooled, and a thermal crown T lower than the initial crown I is generated, and the temperature distribution thereof also has an intermediate shape as shown in Fig. a.

As a result, in the heating chamber, meandering is more often a problem than narrowing.

In view of the above points, the present invention firstly adjusts in advance the crown of the in-furnace hearth roll to an appropriate amount of crown to prevent meandering and squeezing, depending on the size (thickness and width) of the strip fed into the continuous annealing furnace. At the same time, during operation, the meandering and narrowing amount of the IJ knob is detected,
Based on this, meandering and narrowing can be corrected.
It is characterized by controlling the crown of the throttle, so that meandering and squeezing do not occur even when strips of any size are fed, allowing continuous annealing work to be performed stably and high-quality products obtained. It is.

The present invention will be explained below with reference to the drawings.

FIG. 4 shows an example of a control device for carrying out the method of the present invention, in which 1 is a hollow nozzle roll, 2 is a strip run by the hearth roll 1, and 3 is a strip 2 on the exit side. 4 is a signal processing circuit that processes the signal from the detector 3 and outputs the amount of meandering in an appropriate unit; 5 is the signal processing circuit 4;
an arithmetic circuit for inputting and calculating the meandering amount from and determining an appropriate refrigerant flow rate and temperature, 6 a flow control device for sending out the flow rate installed by the arithmetic circuit 5;
7 is a temperature control device for adjusting the refrigerant to the same set temperature.

Further, 8 is a refrigerant supply device, 9 is a setting device for presetting an appropriate amount of refrigerant flow rate and temperature according to the thickness and width of the strip 2 to be passed, and 10 is a setting device for adjusting the flow rate and temperature appropriately. It is a ladder to a nozzle for spraying the pumped refrigerant onto the inner surface of the roll through a pipe 11 inserted from one axial end of the hearth roll 1.

The refrigerant used for cooling is discharged from the other end in the axial direction of the roll.

Examples of the refrigerant used to cool the hearth roll 1 include water, air, mist, and atmospheric gas.

Also, as the meandering detector 3, an industrial television (ITV) is used.
Any method may be selected, such as a method based on the method, a capacitance method, a magnetic method, etc., and either an edge on one side of the striso 120 or an edge on both sides (as shown in the figure) may be detected.

In the illustrated example, only a meandering detector is installed, but one type of monitor may be used to detect narrowing down, or the two meandering detectors shown may also be used for detecting narrowing down.

For example, in the case of meandering, the width of the strip does not change and is understood as the amount of movement of its edge, but in the case of narrowing, the width of the strip shows a movement that decreases, so this is detected by two detectors and the amount of narrowing is calculated. can be grasped.

Furthermore, a plurality of nozzle headers 10 may be installed radially inside the hearth roll 1, and headers may be installed as needed.
10 The amount of refrigerant jetted in the longitudinal direction can be adjusted, and the hearth roll 1
Parts of the inner surface may have a different cooling effect than other parts.

In addition, when installing a thermal crown control device on the hearth roll of a continuous annealing furnace as in the present invention, it is better to apply it to all the hearth rolls in the furnace than to apply it to all the hearth rolls in the furnace. Since it is often known whether meandering or squeezing is likely to occur, it is practical to control only the scroll at particularly required positions.

Next, FIG. 5 shows another example of a control device for carrying out the method of the present invention, in which the nozzle header 10a is installed close to the outside of the throttle 1.

In this example, it is preferable to use an atmosphere glass used for annealing as the refrigerant.

Although the part-side mechanism is not particularly shown in FIG. 5, it is the same as in FIG. 4, and there is no change in the flow rate and temperature control of the atmospheric gas.

The control method of the present invention will be explained below using the illustrated device as an example.

First, before feeding the strip 2 into the continuous annealing furnace, the flow rate and temperature of the refrigerant are preset using the setting device 9 based on the width and thickness of the strip, thereby controlling the flow rate and temperature. The refrigerant is transferred to nozzle header 1.
It is sprayed from 0 to the hearth roll 1 and maintained at an appropriate amount of rounds.

In this state, the IJ tube 2 is fed into the furnace, but the
Due to causes such as the difference between the furnace atmosphere temperature and the strip temperature as shown in the figure, the amount of crown that is kept at an appropriate amount changes, which may cause meandering or squeezing of the strip.

When meandering or narrowing (assuming only meandering occurs for convenience) in the strip 2 during threading, the amount of meandering is detected by the detector 3, and the signal is processed by the signal processing circuit 4 and sent to the arithmetic circuit 5. It will be done.

The arithmetic circuit 5 calculates the flow rate and temperature of the refrigerant required to return the flow amount to a proper amount by comparing the meandering amount sent with a preset value.

Once the flow rate and temperature of the refrigerant are determined, the flow rate control device 6 and temperature control device 7 are activated by the signal, and the refrigerant at the set flow rate and temperature is supplied through the piping 11 and blown onto the inner or outer surface of the hearth roll 1. and adjust the amount of rounds as appropriate.

If the crown amount of hearth roll 1 is appropriate,
The meandering of the J-tube 2 is correctly corrected by the center IJing effect.

Note that if the control range is narrow, it is sufficient to adjust either the refrigerant flow rate or the temperature.

As explained above, according to the present invention, the crown amount of the hearth roll can be appropriately determined according to the size of the strip fed into the furnace, and even if meandering and/or squeezing occur during strip threading, the crown amount of the hearth roll can be appropriately determined according to the size of the strip fed into the furnace. In order to correct this,
Since the thermal crown of the hearth roll can be controlled, the strip can be threaded in a stable manner at all times, and annealing operations can be carried out continuously and stably, and high-quality products with high yields can be obtained. .

[Brief explanation of the drawing]

Figures 1a and b are front views showing examples of roll crowns;
Figure ayb is a roll surface temperature distribution diagram and a diagram of the occurrence of thermal crown to explain thermal crown in the annealing furnace cooling chamber, and Figure 3a. b is a roll surface temperature distribution diagram and a diagram of the occurrence of thermal crown to explain the thermal crown in the annealing furnace heating chamber; FIG. 4 is a control system diagram for implementing the present invention;
FIG. 5 is a control system diagram showing another example of the present invention. 1... hearth roll, 2... strip, 3...
Meandering detector, 4... Signal processing circuit, 5... Arithmetic circuit, 6... Flow rate control device, 7... Temperature control device, 8... Refrigerant supply device, 9... Setting device, 10... Nozzle header 11... Piping.

Claims (1)

[Claims] 1. A refrigerant whose flow rate and temperature are adjusted so as to obtain a crown commensurate with the size of the strip fed into the continuous annealing furnace is sprayed onto the inside or outside of the Harmer roll in the furnace, and the meandering and/or 1. A crown control method for a hearth roll of a continuous annealing furnace, characterized in that the thermal crown of the hearth roll is properly controlled by detecting the amount of throttling and further adjusting the flow rate and temperature of the refrigerant based on this.