JP2001323325A - Apparatus and method for cooling metal strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roll cooling apparatus which can efficiently cool a metal strip without deformation of the shape. SOLUTION: When the metal strip is wound around a cooling roll with a heat pipe built therein, the cooling apparatus capable of controlling the cooling in the width direction is provided outside a cooling roll on the side not in contact with the metal strip, and a holding roll for pinching the metal strip to the cooling roll is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll cooling system capable of efficiently cooling a traveling metal strip such as a steel plate or an aluminum plate while preventing deterioration of the shape of the steel plate due to uneven cooling. The present invention relates to an apparatus and a cooling method.

[0002]

2. Description of the Related Art In a heat treatment furnace, a cooling method such as gas jet cooling or mist cooling is used as a method for cooling a heated metal strip. In particular, when the metal strip is at a high temperature, these cooling methods are effective because the cooling capacity is high and the shape can be prevented from being deteriorated due to cooling. on the other hand,
When the temperature of the metal strip decreases, the cooling capacity of these methods decreases, so that immersion cooling or roll cooling with water having a high cooling capacity is used.

[0003] The immersion cooling of water is simple and efficient, but it is easily oxidized, so post-treatment such as scale removal is required. Therefore, roll cooling that can be used in a non-oxidizing atmosphere where post-treatment is not required. Are also used. Roll cooling has the advantage that it has a high heat transfer capability for contact heat transfer and can be used in a non-oxidizing atmosphere. However, it has a problem in that a thermal crown is formed on the roll, and poor contact with the roll is likely to occur.

[0004]

As means for preventing the occurrence of a thermal crown, there has been proposed a method in which a heat pipe is provided inside a roll to transfer heat quickly. JP 57
164930 or JP-A-57-16493.
No. 2 proposes incorporating a heat pipe inside the cooling roll.

However, the heat transfer in the heat pipe is performed at a very high speed, but the heat from the surface of the cooling roll is limited by heat diffusion in the metal constituting the roll shell. In this case, there is a problem that a temperature distribution is generated in the inside, the thermal crown cannot be effectively prevented, and the cooling of the steel sheet becomes uneven.

Further, a steel plate is wound around a plurality of cooling rolls also having a built-in heat pipe for cooling.
In the cooling device described in JP-A-123854, there is a problem that the number of cooling rolls must be increased because the contact surface pressure to the rolls is only the tension of the steel plate, and the cooling capacity cannot be increased. The present invention aims to solve these problems.

[0007]

The gist of the present invention to achieve the above object is as follows. (1) In a device for cooling a metal strip using a cooling roll, a roll having a built-in heat pipe in the roll width direction is used as the cooling roll, and cooling for cooling the outer surface of the roll that is not in contact with the metal strip. A cooling device for a metal strip, comprising means. (2) The cooling device according to the above (1), wherein a gas cooling device and / or a cooling roll is provided as means for cooling the outer surface of the roll. (3) The cooling device according to the above (2), wherein the gas cooling device and / or the cooling roll is provided with a unit for performing cooling control in the width direction. (4) The cooling device according to (3), further including a temperature measuring function of measuring a temperature distribution in a width direction of the cooling roll on a side not in contact with the metal strip. (5) The metal strip cooling device according to any one of (1) to (4), wherein one or more pinch rolls for pinching the metal strip in contact with the cooling roll are provided. Cooling system. (6) In the cooling device according to the above (4), the temperature distribution in the width direction of the cooling roll on the side not in contact with the metal strip is measured,
Cooling the metal strip while controlling the temperature distribution of the cooling roll that cools the metal strip by controlling the cooling capacity in the width direction of the gas cooling device and / or the cooling roll based on the measured temperature distribution. Metal strip cooling method.

[0008]

FIG. 1 is a block diagram showing an embodiment of the present invention.
It will be described based on. FIG. 1 is a schematic side view illustrating a cooling device for a metal strip according to the present invention. The metal strip 1 moves from left to right in the drawing. During this time, cooling is performed while winding around the cooling rolls 2 and 3.

On the way, the metal strips 1 are
6 and 7 press against the cooling rolls 2 and 3. The reason for this is to increase the cooling capacity by pinching because the contact surface pressure does not form and the cooling capacity is not sufficient just by winding, the roll shape is deteriorated due to manufacturing accuracy, and the roll is deformed due to the thermal deformation of the roll. If the contact between the
This is for stably bringing the metal strip into contact with the cooling rolls 2 and 3. If the contact between the cooling roll and the metal strip is sufficient, heat is transmitted from the hot metal strip 1 to the cooling rolls 2 and 3. A metal may be used as the pressing roll, and a carbon roll or the like is effective when scratching becomes a problem. At a temperature at which the heat-resistant rubber roll can be used, the heat-resistant rubber roll is effective.

[0010] However, the cooling roll is generally made of metal in terms of strength, life, temperature, etc., but since the thermal conductivity in the metal is not so good, heat tends to stay near the roll surface. As a result, the roll surface temperature rises, which causes a decrease in cooling capacity. In addition, since the temperature distribution is generated in the roll width direction and the thickness direction, the roll expands based on the roll temperature distribution, and a drum-shaped thermal crown having a generally bulged center is generated. When the thermal crown is generated, the contact between the metal strip and the cooling roll is further deteriorated, so that there is a problem in that the phenomenon that the metal strip is unevenly cooled and the shape of the metal strip is deteriorated is accelerated.

In order to prevent the thermal crown, as a means for equalizing the roll temperature, a method of inserting a heat pipe inside the roll and diffusing the heat entering from the center of the roll in the width direction to equalize the roll temperature. Has been proposed. Certainly, in the case of rolls with embedded heat pipes, when heat reaches the heat pipes, heat diffusion occurs, but as described above, the heat received from the metal strip stays near the roll surface, so an effective roll In the cross-sectional direction, a temperature distribution is unavoidable, and it is difficult to make the roll temperature uniform. In particular, when the conveying speed is high, the heat must be in contact with the hot metal strip one after another before diffusing into the roll, so that the effect of the heat pipe is further reduced.

Therefore, the present invention employs a method of effectively removing the heat remaining on the surface of the cooling roll, and effectively diffusing the heat that has not been completely removed and diffused in the roll in the width direction. Since the heat taken from the metal strip becomes maximum when the metal strip is separated from the cooling roll, effective cooling is possible if heat is taken from the surface of the cooling roll from this time.

Therefore, in the present invention, the cooling rolls 2 and 3 are provided with a cooling device on the side not in contact with the metal strip to remove heat from the outside of the cooling rolls. FIG. 1 shows an example in which a gas blowing device 8 is provided for the cooling roll 2 and a cooling roll 9 for cooling the roll is provided for the cooling roll 3.

The gas blowing device 8 blows a cooling gas from a nozzle, and may be used in consideration of an atmosphere such as air, nitrogen, and hydrogen and a cooling capacity. Cooling roll 9
In the case where the rolls come into contact with each other, the portion where the high-temperature thermal crown has grown preferentially comes into contact, so that heat is taken from the high-temperature portion, and the temperature of the cooling roll 3 is made uniform. By doing so, the temperature of the cooling roll can be made uniform, and thermal crown can be prevented.

However, in practice, the temperature of the cooling roll is not always equalized due to the depth of burying of the heat pipe and the thermal conductivity of the material of the roll shell. Therefore, in the present invention, by dividing the cooling device in the roll width direction and measuring the temperature distribution in the width direction of the cooling roll, the cooling capacity is controlled in the roll width direction by the measured temperature distribution, so that the metal is more effectively formed. The strip can be cooled. The cooling control method can be realized, for example, by controlling the gas flow rate in the gas blowing device 8, or by controlling the pressing pressure of the cooling roll 9.

As described above, the present invention controls the temperature distribution of the chill roll to prevent the thermal crown of the roll, stabilizes the contact between the metal strip and the chill roll, increases the cooling efficiency, and achieves uniform cooling. And also prevent the shape from deteriorating. Further, by providing the holding roll, the cooling roll can be stably brought into contact with the metal strip even in a situation where the metal strip is difficult to contact, thereby enabling effective cooling.

By adopting the above-mentioned method, the metal strip can be effectively and uniformly cooled. However, in order to cool the metal strip more effectively, it is necessary to pinch the metal strip. Can be realized. In other words, if the metal strip is simply wound around the cooling roll, the pressing pressure when the metal strip is wound around the cooling roll is extremely small because the contact area is large, and the actual contact area between the metal strip and the cooling roll is small. The cooling capacity does not increase because it is small. Of course, increasing the tension of the metal strip slightly increases the contact pressure, but its contribution is extremely small because the contact area is larger. Rather, the adverse effects such as deformation and meandering of the metal strip are larger and impractical.

Therefore, in the present invention, a method of pinching the metal strip with a pinch roll from the opposite side of the cooling roll is used to increase the contact pressure and improve the cooling capacity. By pinching, the heat transfer capability of the contact surface can be increased from several tens to several hundreds of times depending on the pressing pressure.
As for the pinch roll, use a roll with a built-in heat pipe like a cooling roll to improve the contact, and if the cooling roll is also used, the cooling capacity will be further improved, and if temperature is possible, use a rubber roll etc. The metal strip can be stably brought into contact with the cooling roll. The number of pinch rolls to be installed is not particularly limited, and may be determined as needed.

[0019]

EXAMPLE An experiment was conducted to confirm the effectiveness of the present heating method. In the experiment, a steel sheet heated to 700 ° C. was wound around a roll for cooling, and the temperature distribution before and after cooling and the shape of the cooled steel sheet were compared. The cooling roll used in the experiment was a roll of S45C having a diameter of 350 mm and a body length of 600 mm.
The shell thickness was 40 mm. An experiment was performed using a cooling roll according to the present invention in which a heat pipe using water as a refrigerant was embedded in a shell, and a conventional roll using no heat pipe as a comparison. 0.2mm thick, 400mm wide
Was heated to 700 ° C. at 20 mpm and then contacted with a cooling roll for cooling. The winding angle of the steel sheet around the roll was 90 degrees.

In an experiment, when a cooling roll with a built-in heat pipe according to the present invention was used and a gas was uniformly blown at a rate of 60 m / s to a non-contact portion of a steel plate of the roll to cool the roll A, the roll temperature distribution was measured in the experiment A. B, experiment B when cooling by blowing gas at 60 m / s so as to control roll temperature
A heat pipe using water as a refrigerant as a roll for a steel sheet pinch is embedded in a shell and has a diameter of 250 mm and a body length of 600.
mm S45C cooling roll, rolling force 1 kg / m
C when pressed with m, D as a comparative example when cooling was performed using a conventional roll, and E when cooled with a heat pipe alone.

The results are shown in Table 1. When the conventional roll was used, in the case of D, only the center of the steel sheet was cooled due to the thermal crown of the roll, and the temperature deviation was large. Further, in the case of cooling E using the cooling roll with a built-in heat pipe alone, the temperature deviation was eliminated as compared with the experiment D, but the shape defect was reduced but not eliminated. On the other hand, in Experiment A according to the present invention, the temperature deviation was reduced, the cooling temperature was lowered, and the shape was good. Experiments B and C show the temperature deviation,
Both the amount of temperature drop and the shape of the steel sheet were good, confirming the effectiveness of the present invention.

[0022]

[Table 1]

[0023]

By using the cooling device of the present invention, it is possible to prevent the deterioration of the shape of the metal strip at the time of roll cooling, which has been a problem in the past, and to achieve effective cooling even in a region where the cooling capacity at medium to low temperatures is reduced. Therefore, it is not necessary to lengthen the equipment, and it is possible to provide a cooling equipment that is advantageous in terms of cost and space. Further, since the atmosphere can be made non-oxidizing, post-treatment such as pickling is not required.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating a cooling device for a metal strip according to the present invention.

[Explanation of symbols]

 1: Metal strip 2-3: Cooling roll 4-7: Holding roll 8: Gas blowing device 9: Cooling roll

Claims (6)

[Claims] An apparatus for cooling a metal strip using a cooling roll, wherein a roll having a built-in heat pipe in a roll width direction is used as the cooling roll, and cooling of an outer surface of the roll that is not in contact with the metal strip is performed. A cooling device for a metal strip, wherein cooling means for performing the cooling is provided. 2. The cooling device for a metal strip according to claim 1, wherein one or both of a gas cooling device and a cooling roll are provided as a means for cooling the outer surface of the roll. 3. The cooling device for a metal strip according to claim 2, wherein the gas cooling device and the cooling roll are provided with a means for controlling cooling in the width direction. 4. The cooling apparatus according to claim 3, further comprising a temperature measuring function for measuring a temperature distribution in a width direction of the cooling roll on a side not in contact with the metal strip. 5. The metal strip cooling device according to claim 1, wherein one or more pinch rolls for pinching the metal strip in contact with the cooling roll are provided. Cooling system. 6. The cooling device according to claim 4, wherein a temperature distribution in a width direction of the cooling roll on a side not in contact with the metal strip is measured, and any one of a gas cooling device and a cooling roll is determined based on the measured temperature distribution. A method for cooling a metal strip, wherein the cooling capacity in both width directions is controlled, and the metal strip is cooled while controlling the temperature distribution of a cooling roll for cooling the metal strip.