JP2004059970A - Apparatus for cooling steel strip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for cooling a steel strip in a vertical pass of a continuous annealing facility, by which the occurrence of meandering and rolling flaw of the steel strip can be prevented by performing the uniform cooling in the width direction of the steel strip. <P>SOLUTION: In the cooling unit of the steel strip in the vertical pass of the continuous annealing facility, in the upper stage unit of the vertical pass, radiately cooling nozzles inclined toward both edge parts in the width direction of the steel strip, are set at the lower surface side (minus surface side) in the horizontal pass of the lowered steel strip. Further, in the lower stage unit of the vertical pass, the radiately cooling nozzles are set at the upper surface side (plus surface side) in the horizontal pass of the lowered steel strip. Desirably, in the upper stage unit of the vertical pass, coolant-supplying headers divided in the width direction of the steel strip, are arranged at the lower surface side (minus surface side) in the horizontal pass of the lowered steel strip. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cooling apparatus for a steel strip in a vertical pass of a continuous annealing facility.
More specifically, the present invention relates to a steel strip cooling device that performs uniform cooling in the width direction of a steel strip in continuous annealing equipment.
[0002]
[Prior art]
Various proposals have hitherto been made and put to practical use regarding a cooling device for a steel strip in a continuous annealing facility.
FIG. 1 is a diagram showing the entire configuration of the continuous annealing equipment.
In FIG. 1, a steel strip subjected to tension control by dancer rolls and bridle rolls (furnace entrance side BR, furnace exit side BR) is heated by a heating zone (HF) and retained by a soaking zone (SF). It is cooled by the primary cooling zone (1CF).
Next, after the overaging treatment is performed in the overaging zone (OAF), it is cooled to room temperature by the secondary cooling zone (2CF) and the water cooling tank (WQ).
[0003]
FIG. 2 is a diagram illustrating a configuration of a cooling device for a steel strip in a vertical path of a primary cooling zone of a continuous annealing facility.
In FIG. 2, the steel strip 1 bent vertically by the direction change roll 2 is cooled by the refrigerant injected from the refrigerant supply header 4.
The bending back by the direction change roll 2 causes a warp (C warp) in the width direction of the steel strip 1, and dripping water due to cooling water is generated in a central part of the steel strip 1. If the steel strip 1 meanders in the width direction due to overcooling or a temperature deviation in the width direction, roll flaws may be generated in the steel strip, which causes problems in operation and quality. I was
Further, when the line speed is increased, the supply amount of the refrigerant is increased, and it is easy to meander. Therefore, it is necessary to perform the operation at a reduced line speed.
[0004]
FIG. 3 is a diagram showing a temperature distribution in a sheet width direction when a steel strip is cooled by a conventional cooling device.
In FIG. 3, the horizontal axis indicates the position in the sheet width direction, and the vertical axis indicates the deviation (° C.) from the center target sheet temperature.
In the example of FIG. 3, the temperature of the steel strip center is low due to the effect of the dripping water generated in the center of the steel strip, and the temperature of the steel strip edge is also low due to the heat removal from the steel strip edge end face.
In addition, the temperature of the left side (DS) is lower than that of the right side (WS) in FIG. 3, and the shape of the left side (DS) of the steel strip is deteriorated. Was.
[0005]
FIG. 4 is a diagram showing a shape of a steel strip cooled by a conventional cooling device.
In FIG. 4, middle elongation occurs due to supercooling of the steel strip center part, ear waves occur due to supercooling of the edge part, and the shape is deteriorated because the temperature on the left side (DS) of the steel strip is low.
As a conventional technique aiming at uniform cooling in the width direction of the steel strip, for example, WO97 / 44498 discloses a technique in which a cooling nozzle is inclined toward both ends in the width direction of the steel strip to generate the cooling nozzle in the center of the steel strip. A method for preventing dripping water is disclosed.
However, in this prior art, the structure of the inclined cooling nozzles and the structure of the widthwise divided headers are disclosed, but the specific arrangement of the inclined cooling nozzles and the widthwise divided headers is not disclosed.
[0006]
[Problems to be solved by the invention]
The present invention solves the problems of the prior art as described above, performs uniform cooling in the width direction of the steel strip, and prevents the meandering of the steel strip and the occurrence of roll flaws in the vertical pass of the continuous annealing equipment. It is an object to provide a cooling device for a steel strip.
[0007]
[Means for Solving the Problems]
The present invention has been made by examining the specific arrangement of the inclined cooling nozzle and the width direction divided header in order to solve the above-mentioned problem, and the gist thereof is described in the claims. It is as follows.
(1) A cooling apparatus for a steel strip in a vertical pass of a continuous annealing facility, wherein an upper unit of the vertical pass has a lower side (−side) in a horizontal pass of a descending steel strip in a width direction of the steel strip. Radiant cooling nozzles inclined toward both ends are installed, and the lower unit of the vertical path is provided with a radial cooling nozzle on the upper surface side (+ surface side) in the horizontal path of the descending steel strip. Characteristic steel strip cooling device.
(2) The upper unit of the vertical path is provided with refrigerant supply headers divided in the width direction of the steel strip on the lower surface side (−surface side) of the descending steel strip in the horizontal path, so that both ends of the steel strip are provided. The cooling device for a steel strip according to (1), wherein the supply of the refrigerant to the steel strip can be selectively started and stopped.
[0008]
(3) The upper unit of the vertical path is provided with a combination of a refrigerant supply header divided in the width direction of the steel strip and a refrigerant supply header not divided in the width direction of the steel strip (1). Or the cooling device of the steel strip as described in (2).
(4) The steel strip cooling device according to any one of (1) to (3), wherein the refrigerant is a mixture of a cooling gas and cooling water.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 5 is a view showing an embodiment of a steel strip cooling device according to the present invention.
In FIG. 5, the steel strip 1 is bent back vertically by the direction change roll 2 and transported to a vertical path.
This vertical path is provided with a refrigerant supply header 4 for cooling by spraying a refrigerant from both sides of the steel strip 1. In this embodiment, a total of 60 stages of refrigerant supply headers are provided on both sides of the steel strip 1, 30 stages on one side. Is installed.
The direction changing roll 2 is provided with a convex crown having a middle height at the center of the roll. When the steel band 1 is bent back by the direction changing roll 2, the warp in the width direction of the steel band 1 (C warpage). ) Occurs, and the direction of this warp is convex on the upper surface side (the + surface side shown in FIG. 5) of the horizontal pass of the steel strip in the upper unit of the vertical path (one unit in FIG. 5).
Here, the upper unit of the vertical path refers to a group of refrigerant supply headers installed above the vertical path in the continuous annealing furnace.
[0010]
Therefore, dripping water from the refrigerant sprayed on the steel strip 1 is likely to be generated in the concave portion on the lower surface side (the negative side in FIG. 5) of the horizontal path of the steel strip.
Therefore, the upper unit (one unit in FIG. 5) of the vertical path is provided with a radiation cooling nozzle inclined toward both ends in the width direction of the steel strip on the lower surface side (negative side) of the descending steel strip in the horizontal path. By installing the steel strip, dripping water generated in the center of the steel strip can be eliminated in the direction of both ends in the width direction of the steel strip, and as a result, supercooling of the steel strip center can be reduced.
In FIG. 5, the coolant supply headers surrounded by alternate long and short dash lines are locations where the radiant cooling nozzles are installed. In the present embodiment, the radiant cooling nozzles are installed on all the coolant supply headers on the negative side of one unit. However, the radiant cooling nozzles do not necessarily need to be installed in all the coolant supply headers.
[0011]
On the other hand, in the lower unit of the vertical path (two units in FIG. 5), since the steel strip 1 is bent back in the opposite direction by the direction change roll 3, the direction of the warp (C warp) in the width direction of the steel strip 1 is as follows. The steel strip has a convex shape on the lower surface side (-surface side shown in FIG. 5) of the horizontal path.
In addition, the position where the warp direction of the steel strip is reversed exists below the boundary between the 1 unit and the 2 unit because the warp of one unit tends to be strengthened by the effect of the dripping water.
Therefore, the lower unit of the vertical path (two units in FIG. 5) is provided with six refrigerant supply headers from the lower part of the upper surface side (+ side shown in FIG. 5) in the horizontal path of the descending steel strip. By installing radiant cooling nozzles inclined toward both ends in the width direction, dripping water generated in the center of the steel strip can be eliminated in the direction of both ends in the width direction of the steel strip. The supercooling of the section can be reduced.
Here, the lower unit of the vertical path refers to a group of refrigerant supply headers installed below the vertical path in the continuous annealing furnace.
The inclined cooling nozzle is preferentially installed from the lower stage because the lower stage closer to the direction changing roll 3 has a larger warpage of the steel strip 1 and a larger supercooling of the steel strip center.
[0012]
Next, the installation location of the width-wise divided header in the present embodiment will be described.
In FIG. 5, eight refrigerant supply headers on the negative side of one unit of steel strip indicated by oblique lines are used as width direction divided headers.
By installing the width direction division header, supply of the refrigerant to both ends of the steel strip can be selectively started and stopped, and overcooling of the steel strip edge can be prevented.
The number of headers to be installed in the width direction is determined by the temperature difference between the steel strip center and the edge to prevent plastic deformation of IF steel, which is a soft steel type that is apt to undergo plastic deformation due to the temperature difference between the steel strip center and the edge. In order to reduce the temperature to 20 ° C. or lower, the temperature was set by determining the number of refrigerant supply headers at which the injection of the refrigerant to the steel strip edge should be stopped. In the present embodiment, the width direction division header is installed in only one unit, but the width direction division header may be installed in two units.
[0013]
The upper unit of the vertical path is preferably provided with a combination of a refrigerant supply header divided in the width direction of the steel strip and a refrigerant supply header not divided in the width direction of the steel strip. In the three-stage block, it is preferable that the upper stage and the middle stage be a refrigerant supply header divided in the width direction of the steel strip, and the lower stage be a refrigerant supply header not divided in the width direction of the steel band.
Immediately after the coolant is injected by the width division header, the water film is concentrated on the center of the width of the plate, and if it is left as it is, cooling unevenness can occur in the width direction. With this arrangement, it is possible to prevent the water film from being concentrated on the center of the plate width, thereby preventing uneven cooling.
[0014]
FIG. 6 is a diagram illustrating an inclined cooling nozzle used in the present invention.
In FIG. 6, the refrigerant is blown from the refrigerant supply header 4 to the steel strip 1 through the inclined cooling nozzle.
Since the inclined cooling nozzle 5 is inclined in the direction from the center of the steel strip to both ends of the steel strip, dripping water generated at the center of the steel strip can be eliminated in the direction of the steel strip edge. It is possible to prevent the belt center from being supercooled.
FIG. 7 is a diagram illustrating a split header in the steel strip width direction.
In FIG. 7, the three headers at the top, middle, and bottom indicate one of the N blocks in FIG.
The upper header and the middle header are each divided into five in the width direction of the steel strip, and a solenoid valve (SOV) is provided under the divided header to selectively start and stop the supply of the refrigerant. be able to.
[0015]
In particular, solenoid valves (SOV) are installed in the left and right refrigerant supply lines of the steel strip in the most frequently used middle section divided header, and the refrigerant can be supplied to only one of the left and right headers. it can.
By using this width direction divided header, by starting and stopping the supply of the refrigerant for each header, it is not necessary to perform complicated flow rate control, and it is possible to easily prevent overcooling of the steel strip edge portion, As a result, it is possible to prevent the meandering of the steel strip and the occurrence of roll flaws.
In addition, a shutoff valve (SOV) and a flow control valve (FCV) are provided under each header.
[0016]
The lower header in FIG. 7 is a normal header that is not a width-wise split header, so that the influence of dripping water generated by the upper and interrupted split headers is canceled once here, thereby cooling the next block. By preventing overcooling in the idle running portion where water is not directly injected, the effect of uniform cooling in the width direction can be further enhanced.
As the refrigerant, a mixture of an inert gas such as N2 and cooling water is preferable from the viewpoint of cooling capacity and availability, and in particular, a supply port of a gas used for the refrigerant is provided on one side of the refrigerant supply header. In this case, an imbalance in the air flow occurs in the width direction of the steel strip. Therefore, by changing the supply balance between the left and right cooling water, the cooling speed in the width direction of the steel strip can be made uniform.
[0017]
【The invention's effect】
According to the present invention, it is possible to provide a cooling device for a steel strip in a vertical pass of a continuous annealing facility capable of performing uniform cooling in a width direction of the steel strip and preventing meandering of the steel strip and occurrence of roll flaws. Specifically, the following industrially significant effects are obtained.
1) Since the inclined cooling nozzle is installed at a position where dripping water having a large warp (C warp) in the width direction of the steel strip in the vertical pass of the continuous annealing equipment is generated, the effect of preventing excessive cooling of the steel strip center is remarkable.
2) Since the supply of the refrigerant to the steel strip edge can be selectively started and stopped by using the width direction division header, overcooling of the steel strip edge can be prevented by a simple method.
3) Since the meandering and roll flaws of the steel strip can be reduced, the line speed can be increased, so that the production amount can be increased.
[Brief description of the drawings]
FIG. 1 is a diagram showing an entire configuration of a continuous annealing facility.
FIG. 2 is a diagram illustrating a configuration of a cooling device for a steel strip in a vertical path of a primary cooling zone of a continuous annealing facility.
FIG. 3 is a diagram showing a temperature distribution in a sheet width direction when a steel strip is cooled by a conventional cooling device.
FIG. 4 is a view showing a shape of a steel strip cooled by a conventional cooling device.
FIG. 5 is a view showing an embodiment of a steel strip cooling device according to the present invention.
FIG. 6 is a diagram illustrating an inclined cooling nozzle used in the present invention.
FIG. 7 is a view exemplifying a divided header in a steel strip width direction.
[Explanation of symbols]
1: steel strip,
2, 3: turning roll,
4: Refrigerant supply header
5: radiation cooling nozzle,
6: Split header in width direction

Claims (4)

A cooling device for a steel strip in a vertical pass of a continuous annealing facility, wherein the upper unit of the vertical pass includes a lower surface side (-side) of a descending steel strip in a horizontal pass at both ends in a width direction of the steel strip. A radiation cooling nozzle inclined toward the vertical path is installed, and a radiation cooling nozzle is installed on the upper surface side (+ surface side) of the horizontal path of the descending steel strip in the lower unit of the vertical path. Steel strip cooling system. The upper unit of the vertical path is provided with a coolant supply header divided in the width direction of the steel strip on the lower surface side (−surface side) of the descending steel strip in the horizontal path, so that the refrigerant flows to both ends of the steel strip. The steel strip cooling device according to claim 1, wherein the supply can be selectively started and stopped. The upper unit of the vertical path is provided with a combination of a refrigerant supply header divided in the width direction of the steel strip and a refrigerant supply header not divided in the width direction of the steel strip. 3. The cooling device for a steel strip according to 2. 4. The steel strip cooling device according to claim 1, wherein the refrigerant is a mixture of a cooling gas and cooling water. 5.

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