JPH1171618A - Cooling device for rolled product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device capable of cooling a rolled product having a heat transfer rate larger than 350 kCal/m<2> .h. deg.C. SOLUTION: In the rolled product cooling device to cool the rolled product 1 such as steel strip, the rolled product 1 is moved in front of the cooling device, which is provided with a pressing means 4 to press a gas 5 in a box 10. The box 10 is provided with a plurality of fins 11 forming pipes, each fin has at least one gas outlet opening directed toward at least one surface of the rolled product 1, the opening of each fin 11 is arranged in the horizontal direction of the rolled product 1, each space 13 between two fins adjacent to each other has a depth in the direction perpendicular to the surface of the rolled product 1 and a width in the longitudinal direction of the rolled product, and the gas 5 can be discharged by the depth and the width without obstructing the ejection of the gas from adjacent fins.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cooling device for cooling a ferromagnetic or non-ferromagnetic rolled product such as a steel strip.

[0002]

BACKGROUND OF THE INVENTION Heat treatment of rolled products passing vertically through rollers and through a continuous processing chamber is known. Automobile body steel plate manufacturers use continuous annealing or electroplating lines in which the steel is heated to a temperature of 600C to 900C. In this case, these products require rapid and uniform cooling and the temperature of the products must be reduced to below 500 ° C. depending on the quality required.

Therefore, various cooling methods have been used until now. For example, it is known to pass rolled products through cooled rollers, or to immerse rolled products in liquid or semi-liquid media. These two-phase conduction or convection cooling methods
400 kCal / m ² . h. It has a local heat transfer coefficient of at least ° C., but only slightly decreases the temperature. Furthermore, these methods have the disadvantage that the problem of oxidation of the rolled product occurs and, when the rolled product comes into contact with a cooling liquid or a cooling solid, flat defects often occur.

[0004] Another type of method, gas injection, does not have the disadvantages mentioned above. In the steel annealing line disclosed in U.S. Pat. No. 4,363,471, a steel strip passes in front of a box containing a series of gas blower nozzles. However, these nozzles protrude only slightly from the surface of the box. For this reason, discharging the gas after the gas collides with the steel strip is hindered by the box. This creates a back pressure zone between the nozzle and the box, preventing the cooling gas from being blown toward the strip. Furthermore, gas can only escape laterally beyond the width of the rolled product, which can cause uneven cooling at the edges of the rolled product and flattening defects. The heat transfer coefficient produced by a device of this type is 200 kCal / m ² ... In a gas containing a mixture of nitrogen and 5% hydrogen. h. ° C, and lower in the case of air.

[0005] "Development in annealing of rolled steel" magazine (P
radan and Gupta, 1992). The paper "New Technology in KM-CAL for Sheet Gauge" by Kaihara et al.
s is achieved in a 0.7 mm thick rolled product, which is approximately 175 kCal / m ² . h. It is disclosed to correspond to a heat transfer coefficient of ° C. Hirosh listed in the magazine
i Takechi, "Recent developments in metallurgy of continuous annealing of cold-rolled and surface-coated steel sheets," describes an article in which the gas outlet opening is located at a distance of 50 mm from the rolled product. regardless of,
100 ° C for steel plates thinner than 0.35mm
It is disclosed that a cooling rate better than / s cannot be obtained. The cooling rate was 200 kCal /
m ² . h. It corresponds to a heat transfer coefficient of ° C.

In the cooling device disclosed in document WO 92/02316, the extruding members move horizontally between the fin-shaped pipes, which have gas outlet openings transversely to the extruding members. . Only the relative positions of the staggered top and bottom fins are described to obtain uniform cooling of the extrusion. However, this document does not discuss the problem of exhausting the gas after it collides with the extrusion member. Gas impingement on the pushing member is impeded by stagnant gas between the fins.

A paper by IMOSE, "Heating and Cooling Technology in Continuous Annealing" (ISIJTransactio)
ns, Vol. 25, 1985, 911-932), a maximum of 250 kCal / m ² . h. A heat transfer coefficient equal to ° C. is obtained by increasing the gas flow rate and volume, reducing the distance between the rolled product and the blower nozzle, and enriching the gas with hydrogen. However, this value of the heat transfer coefficient is still too small to greatly accelerate the cooling of the rolled product.

In addition, all methods of increasing the hydrogen content to increase the heat transfer rate are difficult to meet safety standards and pose a great danger to the operator.
The table below summarizes the various methods proposed so far for cooling the steel strip from 600 ° C to 400 ° C.

[0009]

[Table 1]

[0010]

An object of the present invention is to provide a non-toxic gas at 350 kCal / m ² . h. An object of the present invention is to provide a gas injection type cooling device capable of cooling a rolled product having a heat transfer coefficient higher than ° C.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is a cooling apparatus for a rolled product for cooling a rolled product such as a steel strip, wherein the rolled product moves in front of the cooling device. Pressurizing means for pressurizing gas in at least one box, said box having a plurality of fins forming a pipe, each fin having at least one gas directed to at least one surface of a rolled product. In the apparatus for cooling a rolled product having an outlet opening, wherein the opening of each fin is arranged in the lateral direction of the rolled product, each space between two adjacent fins is formed on the surface of the rolled product. And a width in a longitudinal direction of the rolled product, wherein the depth and the width allow the gas to flow without obstructing the outflow of gas from the adjacent fins. Exhaustion Defined manner can, with respect to the flow rate of the gas in m ³ / s unit in the set of the outlet of the opening of the fin, m ² unit of space between any one of said adjacent fins and the fin The ratio of the cross-section at is less than 20, said cross-section corresponding to a cross-section lying in a plane perpendicular to said rolled product and parallel to the direction of movement of said rolled product. ing.

[0012] Due to the space provided between the rows of openings, the blown gas can be easily discharged. Thus, the emission of the gas jet is not disturbed and the jet flow rate can reach 220 m / s. By keeping the gas flow below a threshold determined according to the cross section of the separation space, the circulation of the gas in the cooling device is regular and the gas is discharged without uneven cooling of the ends. Will be. Therefore, the cooling device of the present invention is well suited for a continuous heat treatment used in a continuous steel processing line. In this way, a cooling rate significantly higher than that obtained with a conventional gas blower-type device can be obtained. That is, 350 kCal / m ² . h. Heat transfer rates in excess of ° C are obtained.

In one advantageous embodiment of the invention, the depth of each space is greater than 200 mm, preferably 30
Greater than 0 mm. This depth facilitates the return flow of gas after impacting the surface of the rolled product between the rear of the outlet opening and the box. This prevents the accumulation of gas at the level of the outlet openings, so that the blowing of the cooling gas is not obstructed by stagnant gases which are difficult to escape between the outlet openings.

In one advantageous embodiment of the invention, the distance between adjacent fins is between 0.8 and 5 times the distance between each two openings in the same fin. In this way, the fins are located sufficiently close to one another at the level of the gas outlet opening, so that all surfaces of the rolled product passing through the outlet opening are uniformly cooled.

According to another embodiment of the invention, in a cooling installation having at least one cooling device, stabilizing rollers are respectively provided on opposite sides of the cooling device, said stabilizing rollers being rolled. The product is deflected by less than 7 °. In this way, a high cooling capacity can be obtained and the rollers protect the rolled product from vibrations caused by the action of the pressure of the blowing cooling gas. Other features and advantages of the invention will be apparent from the description below.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail with reference to the illustrated embodiments.

[0017] The cooling device of the present invention is incorporated into a continuous annealing line commonly used in the treatment of strip. These strips have a thickness between 0.15 mm and 2.3 mm. The width of these strips is about 0.6m ~
2 m. When heat treating a steel strip, it is necessary to cool the steel strip to a temperature of about 600 ° C. to 900 ° C. to 500 ° C. or less in a very short time. If the strip is coated or hot-quenched by dipping into a bath of molten metal and then cooled, the strip is cooled very quickly after the hot-dip coating of the strip to a temperature between 200 ° C and 300 ° C. It is important to lower it. This cooling is achieved by air.

In FIGS. 1 and 2, a rolled product 1 passes between conveyor rollers 2 vertically in the direction of arrow F. The cooling device has pressurizing means 4 for applying pressure to the box 10 with gas. Box 10 extends parallel to the surface of rolled product 1 and is configured to introduce at least one high velocity stream of pressurized cooling gas 5 into box 10.
Gas is supplied by three fans 4. Of course, it is also possible to use a plurality of blower fans uniformly distributed over the entire height of the box. In addition, the fan 4 can be replaced with a compressor. Although only one box 10 is shown in FIG. 2 for simplicity, the apparatus of the invention advantageously has a second box 10 symmetrically arranged with respect to the rolled product 1 Thereby, it is also possible to simultaneously cool both surfaces of the rolled product 1.

The box 10 has a plurality of pipes in the form of fins 11, and an outlet opening 12 for the gas 5 facing the surface of the rolled product 1 is provided at an end of the fins 11. The openings 12 of each fin 11 are arranged in a row in the lateral direction of the rolled product 1. As shown in FIGS. 3 and 4, each space 13 between two adjacent fins 11 has a depth P in a direction perpendicular to the surface of the rolled product 1 and the length of the rolled product 1. It has a width L in the direction, the depth P and the width L being determined to be large enough to allow the discharge of the gas 5. Each opening 12
Is located at the end of the pipe formed by the fins 11 extending from the box 10 towards the rolled product 1.

After the gas 5 collides with the rolled product 1, the gas 5 flows between the fins toward the rear and can escape. If the cooling has to take place in a protective atmosphere, for example in a mixture of nitrogen and hydrogen, so as not to oxidize the rolled product 1, all cooling devices are surrounded in a known manner by a sealed jacket, Thus, the sprayed gas is recovered and continuously reused in the gas pressurizing means. The recycling operation includes a gas recovery step, a gas cooling step, and a re-injection step. The temperature of the gas 5 in the box 10 is 100 ° C.
Below.

Distance D between adjacent fins 11
Is 0.8 to less than the distance d between the openings 12 of the fins 11.
5 times. This distance D corresponds to the distance between the fins 11 in the flow direction F at the height of the opening 12. The distance d between the openings 12 in the same row is constant. The distance D between the adjacent fins 11 is 30 mm to 2 mm.
It is preferably 00 mm.

Further, as shown in FIG. 4, the openings 12 can be arranged in the longitudinal direction of the rolled product 1, so that the openings 12 form four adjacent square corners. Alternatively, openings 12 can be staggered as shown in FIG. 1, whereby openings 12 form diamond-shaped corners adjacent to one another. Therefore, the distribution of the cooling gas jet is uniform over all surfaces of the rolled product 1. The opening 12 has a hole, such as a circle, rectangle, or elongated shape, or a small groove. Each fin 11 may have a single outlet opening forming a groove towards the rolled product 1.

In order to operate the apparatus correctly and to cool the rolled product 1 rapidly, it is important that the depth P of each separation space 13 is greater than 200 mm, preferably more than 300 mm. . The ratio of the cross section S in m ² of the space 13 between the fin 11 and the adjacent fin 11 to the flow rate in m ³ / s of the gas 5 at the outlet of all the openings 12 of the fin 11 is 20 Less than. The cross section S is located in a plane perpendicular to the rolled product 1 and corresponds to a cross section located parallel to the direction of movement of the rolled product 1. Thus, the flow rate of the gas 5 as it flows through the spaces 13 between the fins 11 and escapes (whether or not the gas is re-used) towards the exhaust or towards the pump suction inlet depends on these spaces 13 Is kept below the critical value of 20 m / s to limit the turbulence in. That is, such a turbulent flow hinders the operation of discharging the gas 5 after the gas 5 collides with the rolled product 1.

The equivalent diameter of the opening 12 is 5 mm to 15 mm. That is, the equivalent diameter is a diameter corresponding to a circular diameter having the same cross-sectional area as the opening 12. Given the foregoing, the cooling device is connected to the outlet opening 12
Is advantageously located at a distance l from the surface of the rolled product 1, i.e. the distance l is between 5 and 12 times the equivalent diameter of the opening 12, preferably between 6 and 6 of the equivalent diameter.
Eight times is advantageous. Advantageously, the box 10 is movable in a direction perpendicular to the rolled product 1 so that the distance l can be changed. That is, when this is done, the box 10
Can be moved closer to the rolled product 1 or farther away from the rolled product 1.

As shown in FIG. 5, each of the fins 11 forming the pipe has a gas flow direction, that is, a box 10.
From the outlet opening 12 to the outlet opening 12. The height of the internal conduit in the fin 11 decreases continuously in the vertical direction F in which the rolled product 1 moves. The outlet opening 12 has a cross-sectional profile whose cross section is substantially identical to the outlet cross section of the fin 11.
This arrangement increases the flow velocity of the gas at the outlet, while limiting undesired head losses. The fin 11 and the outlet opening 12 are made by casting,
It can be manufactured by molding, pressing, assembling and / or machining.

In FIG. 6, the cooling equipment of the present invention has at least one cooling device 21. Stabilizing roller 2
Numerals 0 are provided on opposite sides of the cooling device 21, respectively, and these stabilizing rollers 20 are configured to deflect the rolled product 1 at an angle of less than 7 °. These stabilizing rollers 20 limit the vibration of the rolled product 1 especially when the distance l between the opening 12 and the rolled product 1 is short. The stabilizing roller 20 is movable in the lateral direction,
That is, the rolled product 1 is vertically movable, whereby the rolled product 1 can be aligned, and the stabilizing roller 20 is driven by the electric motor to move the rolled product 1.

The distance in the height direction between the two stabilizing rollers 20 is equal to or less than 6 m, and the height of a stack of pipes (standing tubes) in the same cooling device 21 is equal to or less than 5 m. . This minimizes vibrations of the rolled product 1 and provides a very high cooling capacity. The cooling device 21
Preferably, the rolled product 1 has a plurality of flat fins 11 in the longitudinal direction, each fin 11 having a plurality of openings 1.
2 and thus the opening 12 of the cooling device 21 of the present invention.
Is between 1% and 5% of the surface area covered by the set of fins 11, advantageously between 2% and 4% of this surface area.
%.

The cooling device 21 has at least one box 10 on each side of the rolled product 1. The box 10 has a plurality of boxes 10a, 10b, preferably arranged on the same side as the rolled product 1. In this way, one to seven boxes 10 are arranged side by side over the width of the rolled product 1, the pressures of which are adjusted independently of one another in order to achieve a uniform cooling in the transverse direction. The cooling strength can be varied over the width of the rolled product 1 depending on the desired thermal properties.

In the case of a gas used as a mixture of hydrogen and nitrogen, the hydrogen content is advantageously less than 5%. The gas may be air or pure nitrogen. With the cooling device of the present invention, a strip having a thickness of 0.8 mm can be cooled at a rate exceeding 80 ° C / s. That is, 400 kC
al / m ² . h. It can be cooled at a rate corresponding to a heat transfer coefficient at least equal to ° C. Of course, the present invention is not limited to the embodiments described above, and numerous changes can be made without departing from the scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a front view showing a cooling device of the present invention.

FIG. 2 is a side view of the apparatus of FIG.

FIG. 3 is a conceptual diagram showing an arrangement of a cooling device for a rolled product.

FIG. 4 is a conceptual diagram showing an arrangement of blower openings.

FIG. 5 is a conceptual diagram showing fins of the cooling device of the present invention.

FIG. 6 is a schematic diagram showing a cooling facility according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolled product 2 Conveyor roller 4 Fan 5 Gas 10 Box 11 Fin 12 Outlet opening 13 Space 20 Stabilizing roller 21 Cooling device

Claims (11)

[Claims] An apparatus for cooling a rolled product, such as a steel strip, wherein the rolled product moves in front of the cooling device and pressurizes gas in at least one box. Means 4, said box 10 having a plurality of fins 11 forming a pipe, each fin 11
Has at least one gas outlet opening 12 directed to at least one surface of the rolled product 1,
In the cooling device for a rolled product, which is arranged in the lateral direction of the rolled product 1, each space 13 between two mutually adjacent fins 11 is formed so that It has a depth P in the vertical direction and a width L in the longitudinal direction of the rolled product 1, wherein the depth P and the width L obstruct the outflow of gas from the adjacent fins 11. And the opening 1 of the fin 11
For the flow rate of the gas 5 in m ³ / s at the two sets of outlets, the cross section S in m ² of the space 13 between the fin 11 and any one of the adjacent fins 11 When the ratio is less than 20, the cross section S is located in a plane perpendicular to the rolled product 1 and corresponds to a cross section positioned parallel to the direction of movement of the rolled product 1. An apparatus for cooling a rolled product, characterized in that: 2. The cooling device according to claim 1, wherein the depth P of each space 13 is greater than 200 mm, preferably greater than 300 mm. 3. The distance D between adjacent fins 11.
3 is 0.8 to 5 times the distance d between each two openings 12 in the same fin 11. The cooling device for rolled products according to claim 1 or 2, wherein: 4. The distance D between adjacent fins 11.
The rolled product cooling device according to any one of claims 1 to 3, wherein the diameter of the rolled product is 30 mm to 200 mm. 5. The rolled product according to claim 1, wherein a distance between two openings 12 in the same fin 11 is constant. Cooling system. 6. The rolled product according to claim 1, wherein the cross section of the fin decreases in a direction from the box toward the opening. Cooling system. 7. A plurality of boxes (10a, 10b) arranged on the same side as the rolled product (1).
2. The pressure control device according to claim 1, wherein the a and b are positioned side by side over the width of the rolled product 1 and the pressures in the respective boxes are adjusted independently of one another.
The apparatus for cooling a rolled product according to any one of claims 1 to 6. 8. The method according to claim 1, wherein a distance 1 between the opening 12 and the surface of the rolled product 1 is 5 to 12 times an equivalent diameter of the opening 12. An apparatus for cooling a rolled product according to any one of the preceding claims. 9. The gas 5 is a mixture of hydrogen and nitrogen,
9. Rolled product according to one of the preceding claims, characterized in that the cooling device is surrounded by a sealing enclosure and the gas (5) is continuously recycled. Cooling system. 10. The fin 11 and the opening 12 are cast, formed,
The cooling device for a rolled product according to any one of claims 1 to 9, wherein the device is pressed and assembled and / or machined. 11. A cooling installation having at least one cooling device 21 for a rolled product according to claim 1, wherein the stabilizing rollers 20 are opposite to each other. , Wherein the stabilizing roller 20 deflects the rolled product 1 at an angle smaller than 7 °.