JP2006289407A - Facilities and method for cooling h-section steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide facilities and a method for cooling H-section steel, by which facilities and method, the uniformity of cooling in the width direction of a flange can be further improved in the accelerated cooling of the H-section steel. <P>SOLUTION: A header 30 is partitioned into a plurality of divided headers 31, 32, 33 in the vertical direction. The jetted flow rate density (lowermost end jetted flow rate density) of cooling water at the lowermost end of a multi-hole nozzle 51 arranged on the lowermost stage is larger than the jetted flow rate density of cooling water at the uppermost end of the multi-hole nozzle 51 arranged on the divided header 31 of the lowermost stage or is larger than the jetted flow rate density (uppermost end jetted flow rate density) of cooling water at the uppermost end of the multi-hole nozzle 52 or 53 arranged on the divided header 32 or 33. Further, the lowermost end jetted flow rate density is 1.25 to 2.5 times as large as the uppermost end jetted flow rate density, and the jetted flow rate density is varied with the diameter or the density of the holes of the multi-hole nozzles 51, 52, 53. Further, the cooling water is supplied to the divided header 31 arranged within the range corresponding to the width of the flange of the H-section steel 1 to be cooled. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling equipment and a cooling method for H-section steel, and more particularly to a cooling equipment and a cooling method for H-section steel for uniformly cooling the flange surface of H-section steel.

Conventionally, the manufacture of H-section steel has a step of performing cooling by supplying cooling water as a cooling medium to a high-temperature steel after hot rough rolling and finish rolling. In recent years, the demand for the strength of H-shaped steel has been increasing, and for this reason, examination of alloy components added to the steel and refinement of the material structure by accelerated cooling have been attempted.
Since the response by this alloy component does not necessarily meet the demand for cost reduction, the microstructure is refined by performing “accelerated cooling” with a cooling rate after finish rolling of, for example, 5 ° C./second or more. The strength is increased without relying on.

And in order to perform the accelerated cooling means uniformly, for example, while providing a plurality of cooling water injection ports on the side guide of the conveyance line after finish rolling, the surface facing the flange outer surface of the H-shaped steel of the side guide, What makes an inclined surface, a curved surface, or a level | step difference surface is disclosed (for example, patent document 1).
Moreover, the water cooling header formed in the box shape is divided into a plurality of parts in the vertical direction by the partition plate, and the injection amount of the cooling water injected to the upper edge of the flange of the shape steel is 80% of the injection amount of the cooling water injected from the lowermost surface. What is described above is disclosed (for example, see Patent Document 2).
Further, the injection holes are arranged in multiple stages on the cooling surface side plate of the cooling equipment formed in a box shape (hereinafter sometimes referred to as “porous injection cooling equipment”), and the nozzles of each stage are considered in consideration of the influence of the flowing water from the upper stage. There is one that sets the jet water density (see, for example, Patent Document 3).

JP 2001-191107 A (page 3-4, FIG. 1) Japanese Patent Laid-Open No. 2002-11514 (page 5-6, FIG. 5) JP-A-2-92413 (page 3, FIG. 5)

  However, since the invention disclosed in Patent Document 1 can keep the distance between the cooling water injection port and the flange outer surface of the H-shaped steel constant, the cooling can be stably performed, and the H-shaped steel serves as a side guide. Even if they are close to each other, only the lower end of the flange is in contact with the side guide, so that it is possible to guarantee the specified strength and prevent wrinkles. In order to cope with this, a technique for cooling the entire flange more uniformly was required.

  The invention disclosed in Patent Document 2 increases the injection ratio of the upper part of the flange as compared to the lower part of the flange, and increases the cooling injection amount at the upper part from the lower part, thereby strengthening the injection of the cooling water on the upper end side and increasing the vertical direction of the flange. However, a technology for cooling the entire flange more uniformly has been demanded in order to cope with the further increase in product strength required in recent years.

  Further, in the invention disclosed in Patent Document 3, since the flowing water falling from the upper part of the flange promotes cooling, the injection ratio of the upper part of the flange is increased compared to the lower face of the flange, and the cooling at the upper part of the flange is more than the cooling injection amount at the lower part of the flange. Although the injection amount is increased, the temperature deviation in the flange width direction (same in the lower to upper direction) is promoted, which causes further product shape defects and insufficient strength.

  The present invention is for solving the above-mentioned problem, and the cooling based on the detailed analysis of the temperature data further improves the cooling uniformity in the flange width direction in the accelerated cooling of the H-shaped steel. It aims to provide equipment and cooling method.

(1) The H-shaped steel cooling equipment of the present invention supplies cooling water to a header provided with a multi-hole nozzle, and jets the cooling water from the multi-hole nozzle to cool the flange of the H-section steel. Cooling equipment,
The header is partitioned into a plurality of divided headers in the vertical direction,
The cooling water injection flow density at the lowermost end of the porous nozzle installed in the lowermost divided header among the plurality of divided headers is equal to the cooling water injection flow rate at the uppermost end of the porous nozzle installed in the lowermost divided header. It is characterized by being larger than the density or the jet flow density of the cooling water at the uppermost end of the porous nozzle installed in the divided header excluding the lowermost divided header.

  (2) Moreover, the injection flow density of the cooling water at the lowermost end of the porous nozzle installed in the lowermost divided header among the plurality of divided headers is the uppermost end of the porous nozzle installed in the lowermost divided header. It is 1.25 to 2.5 times the injection flow density of the cooling water or the injection flow density of the cooling water at the uppermost end of the porous nozzle installed in the divided header excluding the lowermost divided header. .

  (3) Moreover, the said injection flow density is changed by the hole diameter of a perforated nozzle.

  (4) Moreover, the said injection flow density is changed by the hole density of a perforated nozzle.

(5) Furthermore, the cooling method of the H-section steel of the present invention cools the divided header in a range corresponding to the flange width of the H-shaped steel to be cooled, in which the porous nozzle is installed and divided into a plurality of divided headers. Supplying water,
Cooling the H-shaped steel flange by ejecting cooling water from the porous nozzle of the divided header supplied with the cooling water,
The cooling water injection flow density at the lowermost end of the multi-hole nozzle installed in the lowermost divided header among the plurality of divided headers is a porous installed in the divided header corresponding to the upper end of the flange width of the H-shaped steel to be cooled. It is characterized by being larger than the injection flow density of the cooling water at the uppermost end of the nozzle.

  (6) Moreover, the divided header corresponding to the upper end of the flange width of the H-shaped steel to be cooled, in which the cooling water injection flow density at the lowermost end of the perforated nozzle installed in the lowermost divided header among the plurality of divided headers It is characterized by being 1.25 to 2.5 times the jet flow density of the cooling water at the uppermost end of the multi-hole nozzle installed in the nozzle.

  (7) Moreover, the said injection flow density is changed by the hole diameter of a perforated nozzle.

  (8) Further, the jet flow density is changed according to the hole density of the porous nozzle.

  Therefore, in the cooling equipment and cooling method for H-shaped steel according to the present invention, the injection flow density of the cooling water at the lowermost end of the multi-hole nozzle installed in the lowermost divided header among the plurality of divided headers is H-shaped to be cooled. Since the cooling water injection flow density at the uppermost end of the multi-hole nozzle installed on the split header corresponding to the upper end of the flange width of the steel is larger than the lower end of the flange width, the flange width direction (lower end) The temperature after cooling in the same direction in the upper end direction becomes uniform.

FIG. 1 is an equipment configuration diagram schematically showing a rolling line in which an H-section steel cooling equipment according to an embodiment of the present invention is arranged.
In FIG. 1, a rolling line 20 includes a rough rolling machine 21 for roughly rolling an H-section steel 1, a finish rolling machine 22 for finish-rolling the roughly rolled H-section steel 1, and a finish-rolled H-section steel 1. It has a cooling facility 23 for cooling, and a hot sawing machine 25 for finish rolling to divide the cooled H-section steel 1 into a predetermined length. In the cooling facility 23, cooling water is supplied to the flange outer surface of the H-section steel 1, and then the temperature distribution in the flange width direction of the H-section steel 1 is measured by the thermometer 24.

FIG. 2 is a front sectional view for explaining the cooling equipment shown in FIG.
In FIG. 2, the cooling facility 23 includes a pair of headers 30 (shown only on the left side in FIG. 2), cooling water supply means (not shown) for supplying cooling water to the headers 30, and the cooling facility 23 of the rolling line 20. Advancing / retreating means (not shown) for advancing / retreating toward the center.
The inside of the header 30 is divided into a plurality of divided headers 31, 32 and 33 by partitions 41 and 42. And the perforated nozzles 51, 52, and 53 are installed in the surface of the division headers 31, 32, and 33 on the center side of the rolling line 20 (the same as the side facing the flange of the H-section steel 1).
In FIG. 2, the partition is installed at two locations and the three-room divided header is illustrated, but the present invention is not limited to this, and four or more divided headers may be provided.

  Therefore, as shown in FIG. 2, the outer surface of the flange 10 of the H-section steel 1 is supplied with the cooling water of the perforated jet almost vertically. By this accelerated cooling by the perforated jet, the surface temperature of the flange 10 of the H-section steel 1 becomes about 640 ° C., whereby the ferrite structure of the cross section of the H-section steel 1 is refined and the strength is increased.

  In addition, acceleration cooling can determine the number of stages of the divided headers 31, 32, 33 to be used according to the flange width of the H-section steel 1 (same as the vertical distance in FIG. 2). For example, when the flange width is small, only the lowermost one divided header 31 can be used, and when the flange width is large, two to three divided headers 31, 32, 33 can be used.

  Further, based on the thickness of the flange 10 of the H-section steel 1 to be manufactured, the required strength target, and the conveyance speed of the H-section steel 1, the length of the cooling equipment 23 to be used (same as the distance in the left-right direction in FIG. 1). ). The header 30 (same as the multi-hole jet device) is a box type that slides on the table roller 26.

In addition, the multi-hole nozzles 51, 52, and 53 (hereinafter sometimes referred to collectively as the "multi-hole nozzle 50") are respectively injected flow density in the width direction of the flange 10 of the H-section steel 1 (the same in the vertical direction in FIG. 2). Is different.
(A) For example, when the hole diameter of the multi-hole nozzle 50 is changed in the flange width direction and the injection flow density is increased, the hole diameter is increased, and when the injection flow density is decreased, the hole diameter is decreased and the flow rate is adjusted.
(I) Alternatively, when the hole density of the multi-hole nozzle 50 is changed to increase the injection flow density, the interval between the plurality of holes is shortened, and when the injection flow density is reduced, the interval between the holes. Lengthen.
(C) Further, this is a method of changing the jet flow rate. When increasing the jet flow density, the thickness of the header 30 on the rolling line 20 side is reduced, or the surface roughness of the inner surface of the hole is reduced ( Reduce the pressure loss (to make it closer to a smoother surface or mirror surface). On the other hand, when the injection flow density is reduced, the thickness of the header 30 on the rolling line 20 side is increased, or the surface roughness of the inner surface of the hole is increased (closer to a rougher surface or an uneven surface). Or make it bigger.

Next, examples of the present invention will be described. Table 1 shows the specifications of the manufactured H-section steel, and Table 2 shows the cooling conditions for the H-section steel. That is, the H-shaped steels 1a and 1b are subjected to finish rolling with the temperature distribution in the flange width direction being almost constant 800 ° C. (same as the finish rolling temperature), and then the flange 10 is cooled to 640 ° C. It was cooled to the same level.
FIG. 3 and FIG. 4 are a schematic diagram showing a jet flow density of cooling water and a temperature distribution diagram after cooling in the examples, respectively. In the H-section steel 1a, only one divided header 31 at the bottom is used, and in the H-section steel 1b, two divided headers 31 and 32 are used.

In FIG. 3, the flow rate distribution in the width direction of the flange 10 is adjusted as follows.
(A) In Comparative Example 1, the flow rate distribution is constant in the header 30 throughout the width direction (see FIG. 3A).
(B) In Comparative Example 2 (only H-section steel 1b), the flow rate is controlled so that the injection flow density of the divided header 32 on the uppermost cooling surface is 1.3 times that of the divided header 31 on the lowermost stage (see FIG. 3 (b)).

(C) In Example 1, the injection flow density at the bottom of the lowermost divided header 31 is monotonically increased in the H-section steel 1a to be 1.3 times that of the uppermost portion of the divided header 31, In 1b, it is monotonously increased to be 1.3 times that of the uppermost part of the divided header 32 (see FIG. 3C).
(D) In the second embodiment, the injection flow density of the lowermost 20 mm portion of the lowermost divided header 31 is higher than that of the uppermost portion of the divided header 31 in the H-section steel 1a, and the lowest of the divided header 32 in the H-section steel 1b. It is increased to 1.3 times that of the upper part (see FIG. 3D).

In FIG. 4, the temperature distribution in the width direction of the flange 10 after cooling is as follows.
(A) In Comparative Example 1, due to the influence of flowing water in the water-cooled portions of the H-section steels 1a and 1b, the cooling capacity decreases as the flanges lower, and the temperature increases as the temperature decreases toward the flanges. (See FIG. 4A). For this reason, since the strength of the lowermost part of the water-cooled part was not sufficient, a strengthening element was added, and the cost was inevitably increased.

  (B) In Comparative Example 2, in the water-cooled part of the H-section steel 1b, the cooling capacity is further lowered at the lower part of the flange due to the influence of the flowing water and the increase in the jet flow density at the upper part of the flange. The temperature distribution increases as the distance increases (see FIG. 4 (b)). For this reason, since the strength of the lowermost part of the water-cooled part was not sufficient, a strengthening element was added, and the cost was inevitably increased.

  (C) In Example 1, since the injection flow density of the lowermost part of the lowermost divided header 31, that is, the portion 20 mm from the lower end of the flange, is monotonically increased to 1.3 times that of the uppermost part, the water cooling part temperature is It becomes uniform (see Table 2), and the temperature distribution is also improved flat (see (c) in FIG. 4). As a result, the temperature at the lower end of the flange water-cooled part is lower than that of Comparative Examples 1 and 2, and the strength is increased. (Conventionally, steel components were designed based on the low strength of the lower end of the flange).

  (D) In Example 2, since the injection flow density of the lowermost 20 mm portion of the lowermost divided header 31 is set to 1.3 times that of the uppermost portion, this portion is cooled more than before (FIG. 4 ( d)). That is, due to thermal diffusion during cooling and immediately after cooling, the water-cooled portion flange lower temperature is lowered in both of the H-section steels 1a and 1b. As a result, as shown in Table 2, the temperature and temperature distribution of the flange water-cooled portions of the H-section steels 1a and 1b are more uniform than those of Comparative Examples 1 and 2, and the temperature at the lower end of the flange water-cooled portion is lowered. Since the strength increased, the addition of strengthening elements could be reduced in both the H-section steels 1a and 1b, and the cost could be reduced (conventional design of steel based on the low strength of the flange lower end) )

In addition, although the example which adjusted the injection flow density with the hole diameter of the porous nozzle 50 was shown in the above Example, this invention is not limited to this, For example, arrangement | positioning of the hole of the porous nozzle 50 is mentioned above. The injection flow density may be adjusted by changing the density of the nozzle, or the pressure loss caused by the cooling water passing through the hole (same as the nozzle injection hole) is controlled to adjust the injection flow density. Also good.
Further, if the ratio of the injection flow density of the multi-hole nozzle 50 is the same as the ratio of the hole area of the nozzle, it is not necessary to adjust the injection pressure and cooling water can be supplied from the same header. is there.

  Moreover, in the above Example, although the injection flow density of a strong cooling part is 1.3 times the normal cooling part, what is necessary is just to be 1.25 to 2.5 times. If it is less than 1.25 times, the effect of making the cooling uniform is reduced. On the other hand, if it is larger than 2.5 times, the portion is overcooled, and the strength exceeds the allowable upper limit.

In order to obtain a predetermined high strength, it is desirable that the injection flow density exceeds 500 liters / minute m ^2. However, as the injection flow density increases, the amount of flowing water also increases, and as a result more flanges where lower portion cools less likely occurs, since the present invention can reliably cool the flange lower portion, even when the injection flow rate density exceeds 500 l / min m ^2, uniform across the flange There is a remarkable effect that high strength can be guaranteed.
Further, when the injection flow density is 1000 liters / minute m ² or more, the tendency that the lower part of the flange is harder to cool than the upper part of the flange becomes more conspicuous. Even in such a case, the present invention has the remarkable effect. It is.

  Moreover, although the division headers 31, 32, and 33 have been described by taking the case where the first and second stages are used as an example when the flange width of the H-section steel 1 is 200 mm and 300 mm, the present invention is not limited to this. However, it may be divided in any way according to the type of flange width of the H-shaped steel to be manufactured. For example, in the case where the flange width of the H-shaped steel to be manufactured is increased at a pitch of 150 mm to 50 mm, the header may be further divided and used.

  As described above, the cooling equipment and cooling method for H-section steel according to the present invention, and the H-section steel having different flange widths can uniformly cool the flange. Therefore, it is widely used as a cooling equipment and cooling method for various H-section steels. Can be used.

The equipment block diagram which shows typically the rolling line by which the cooling equipment of the H-section steel which concerns on embodiment of this invention is arrange | positioned. Sectional drawing of the front view explaining the cooling equipment shown in FIG. The schematic diagram which shows the injection flow density of the cooling water in an Example. The temperature distribution figure after cooling in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 H-section steel 10 Flange 11 Center part 20 Rolling line 21 Rough rolling mill 22 Finishing rolling mill 23 Cooling equipment 24 Thermometer 25 Hot saw machine 30 Header 31 Division header 32 Division header 33 Division header 41 Partition 42 Partition 51 Porous nozzle 52 perforated nozzle 53 perforated nozzle

Claims (8)

H-shaped steel cooling equipment for supplying cooling water to a header in which a multi-hole nozzle is installed, and ejecting the cooling water from the multi-hole nozzle to cool a flange of the H-section steel,
The header is partitioned into a plurality of divided headers in the vertical direction,
The cooling water injection flow density at the lowermost end of the porous nozzle installed in the lowermost divided header among the plurality of divided headers is equal to the cooling water injection flow rate at the uppermost end of the porous nozzle installed in the lowermost divided header. A cooling facility for H-section steel, which is larger than the density or the injection flow density of the cooling water at the uppermost end of the multi-hole nozzle installed in the divided header excluding the lowermost divided header.   The cooling water injection flow density at the lowermost end of the porous nozzle installed in the lowermost divided header among the plurality of divided headers is the cooling water injection flow rate at the uppermost end of the porous nozzle installed in the lowermost divided header. The density or 1.25 to 2.5 times the injection flow density of the cooling water at the uppermost end of the multi-hole nozzle installed in the divided header excluding the lowermost divided header. H-shaped steel cooling equipment.   The cooling equipment for H-section steel according to claim 1 or 2, wherein the jet flow density is changed according to a hole diameter of a multi-hole nozzle.   The H-section steel cooling equipment according to any one of claims 1 to 3, wherein the jet flow density is changed by a hole density of a multi-hole nozzle. A step of supplying cooling water to a divided header in a range corresponding to the flange width of the H-shaped steel to be cooled of the header in which the multi-hole nozzle is installed and divided into a plurality of divided headers;
Cooling the H-shaped steel flange by ejecting cooling water from the porous nozzle of the divided header supplied with the cooling water,
The cooling water injection flow density at the lowermost end of the multi-hole nozzle installed in the lowermost divided header among the plurality of divided headers is a porous installed in the divided header corresponding to the upper end of the flange width of the H-shaped steel to be cooled. A cooling method for H-section steel, which is larger than a jet flow density of cooling water at an uppermost end of a nozzle.   The cooling water injection flow density at the lowermost end of the multi-hole nozzle installed in the lowermost divided header among the plurality of divided headers is a porous installed in the divided header corresponding to the upper end of the flange width of the H-shaped steel to be cooled. 6. The method for cooling an H-section steel according to claim 5, wherein the cooling water jet flow density density at the uppermost end of the nozzle is 1.25 to 2.5 times.   The method of cooling an H-section steel according to claim 5 or 6, wherein the jet flow density is changed depending on a hole diameter of a multi-hole nozzle. The method for cooling an H-section steel according to any one of claims 5 to 7, wherein the jet flow density is changed according to a hole density of a multi-hole nozzle.

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