JP4682669B2 - H-shaped steel cooling equipment and cooling method - Google Patents

Description

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

Conventionally, after hot rough rolling and finish rolling, cooling is performed by supplying cooling water as a cooling medium to the high-temperature steel material. In recent years, the demand for the strength of H-shaped steel has been increasing, and for this reason, examination of alloy components in steel materials and refinement of the material structure by accelerated cooling means have been attempted.
Since the response by this alloy component does not necessarily meet the demand for cost reduction, the cooling rate after finish rolling is, for example, accelerated cooling of 5 ° C / sec or more to refine the structure and increase the strength. ing.
As a conventional H-shaped steel flange cooling device, a large number of holes with a diameter of several millimeters are arranged on the cooling surface side plate of the cooling device main body formed in a box shape, and cooling water is poured into the cooling device main body, and uniformly from the many holes. A uniform cooling of the flange is performed by injecting cooling water (for example, see Patent Document 1).
JP 2001-191107 A

In order to secure the product strength required by the customer, it is necessary to cool the entire flange of the H-shaped steel uniformly, but in the conventional flange cooling device, the cooling water could not be supplied to the flange end. This is because if the cooling water is supplied to the upper end of the flange, the cooling water will pass over the upper part of the flange when the H-shaped steel being transported oscillates up and down, and it will get on the web for a long time. This is because the web stays in the water and causes overcooling of the web.
In addition, the web that is thinner than the flange is easier to cool than the flange even during rolling, but when there is water on it and it cools too much, the web undergoes plastic deformation during the heat shrinkage, and as a result, A web wave is generated and the product cannot be shipped.

  On the other hand, the flange lower end cannot be cooled with water because the flange cooling device is a box type in which H-section steel slides on the table roller. That is, the flange cooling device has a clearance of several mm between the table roller. When this and the thickness of the bottom of the box are added, it becomes about 15-30 mm. Therefore, when supplying the cooling water from the flange cooling device, the cooling water is not supplied to the lowermost portion 15 to 30 mm of the outer surface of the flange.

However, when cooling water is not supplied to the flange end, the end temperature after water cooling is not sufficiently lowered, and the structure cannot be sufficiently refined, resulting in insufficient strength. When manufacturing H-section steel with a flange width of 200 mm or less, the ratio of non-water-cooled regions to the entire flange is relatively high, so not only the local strength at the end but also the average strength of the entire flange is insufficient. Is also a problem.
In addition, the lower part of the cooling surface side plate of the box-type cooling device main body is likely to be clogged with the porous nozzle for long-term use, so that the lower part of the flange is often difficult to cool.
In addition, since the table roller also wears when used for a long period of time, the greater the wear, the lower the pass line, and the lower the tendency for the lower end of the flange to be difficult to cool.
If the flange is somewhat thick, it can be expected that the end temperature will also decrease somewhat due to thermal diffusion in the flange width direction immediately after water cooling. However, if the flange is thin, for example, if the thickness is 25 mm or less, the end portion is not sufficiently cooled. It is.

  In view of the above, an object of the present invention is to provide a cooling facility for H-section steel having high cooling uniformity in the flange width direction in accelerated cooling of the H-section steel.

The H-section steel cooling facility of the present invention is an H-section steel cooling facility that performs water cooling of the outer surface of the flange by a pair of perforated jet devices arranged so as to sandwich the flange of the H-section steel after hot rolling.
Each of the perforated jet devices includes a plurality of headers arranged in the flange width direction of the H-shaped steel, each having a plurality of injection nozzle holes for supplying cooling water,
The header located at the bottom is one that supplies cooling water at 1.2 to 2.5 times the injection flow density of the 15 to 30 mm portion at the lower end of the many injection nozzle holes as compared to other portions. It is.

  Moreover, in the cooling equipment for H-section steel of the present invention, at least one of the plurality of headers, the injection flow density of the upper portion of the injection nozzle hole of 15 to 30 mm is set to 1. The cooling water of 2 to 2.5 times is supplied.

  Furthermore, in the cooling equipment for H-section steel of the present invention, at least one of the plurality of headers excluding the lowermost stage, the injection flow density of the portion of 15 to 30 mm at the lower end of the injection nozzle hole is set to other values. The cooling water is supplied 0.5 to 0.8 times that of the portion.

  In the H-shaped steel cooling facility of the present invention, the adjustment of the injection flow density of the injection nozzle hole is to change the degree of opening and closing of a flow adjustment valve provided in a pipe for supplying cooling water to the injection nozzle hole. It is something that is done by.

  In the H-shaped steel cooling equipment of the present invention, the injection flow density of the injection nozzle holes is adjusted by changing the hole areas of the injection nozzle holes.

  In the H-shaped steel cooling facility of the present invention, the injection flow density of the injection nozzle holes is adjusted by making the intervals between the injection nozzle holes different.

  Moreover, the cooling method of the H-section steel of the present invention is to cool the flange of the H-section steel using the cooling equipment for the H-section steel.

  As described above, according to the present invention, in the cooling equipment for H-section steel that performs water cooling of the outer surface of the flange by a pair of perforated jet devices arranged so as to sandwich the flange of the H-section steel after hot rolling, The jet apparatus is arranged to overlap the flange width direction of the H-shaped steel, and includes a plurality of headers each having a plurality of injection nozzle holes for supplying cooling water. Since the cooling water flow of 1.2 to 2.5 times the injection flow density of the lower end portion of the nozzle hole 15 to 30 mm is 1.2 to 2.5 times that of the other portion, it is uniform in the flange width direction of the H-section steel. High acceleration cooling can be realized, and it has an effect that a high-strength and high-quality H-section steel can be obtained.

FIG. 1 is a cross-sectional view showing a configuration in which a small H-section steel is arranged in the H-section steel cooling facility according to Embodiment 1 of the present invention, and FIG. 2 shows a medium H-section steel arranged in the H-section steel cooling device. It is sectional drawing which shows the structure which made.
The H-section steel cooling equipment according to the present invention cools the rolled H-section steel 1 by continuously injecting cooling water onto the outer surface of the flange while conveying the H-section steel 1 continuously in the H posture. Is to be applied.
Next, the configuration of the H-section steel cooling equipment of this embodiment will be described.
As shown in FIG. 1, the H-shaped steel cooling equipment 13 includes a pair of perforated jet devices 5 positioned on both sides of the flange 2 of the H-shaped steel 1 mounted on a table roller 4. The jet device 5 has a height of 550 mm and a length of 40 m. 3 is a web of the H-section steel 1.

Each of the perforated jet devices 5 is composed of three headers 7A to 7C which are provided with a horizontal partition wall 6 and divided in the vertical direction. Each header 7 </ b> A to 7 </ b> C includes a steel plate side guide 8 having a large number of injection nozzle holes 9, and a cooling water supply unit 10 that supplies cooling water to the large number of injection nozzle holes 9 of the side guide 8.
Further, the large number of injection nozzle holes 9 and the cooling water supply unit 10 in each header 7A to 7C are divided into three blocks 11a to 11c in the upper, middle, and lower, respectively, and the cooling water supply unit 10 of each block 11a to 11c. Are provided with a flow rate adjustment valve 12 for performing flow rate control independently for each block and an on / off control valve 13 for performing on / off control.

  In addition, the height of the whole side guide 8 of the three headers 7A to 7C is 550 mm. The thickness of the side guide 8 of the three headers 7A to 7C is formed so as to gradually increase from the top to the bottom, and is 15 mm to 25 mm. In the side guides 8 of the three headers 7A to 7C, cooling water injection holes 3 each having a diameter of 3 mm are formed in a zigzag pattern at a pitch of 20 mm.

  Further, the surfaces of the side guides 8 of the three headers 7A to 7C that face the outer surface of the flange 2 of the H-section steel 1 gradually become longer as the distance between the outer surface of the flange 2 and the side guide goes from top to bottom. It has become an inclined surface. The inclination angle of the inclined surface is a plane inclined outward by 3.5 ° with respect to the vertical. Thus, the reason why the side guide 8 is an inclined surface is that the cooling water sprayed to the outer surface of the flange flows down the gap between the side guide and the flange. In addition, about the H-section steel whose flange width is 200 mm, it is better to set the inclination angle to 1.6 ° or more, preferably 3 to 6 °.

  The cooling water injection hole 3 provided in the side guide 8 is a straight straight pipe, and the inlet and outlet of the cooling water injection hole 3 are chamfered so that the injected cooling water is not atomized at the cooling water injection outlet. This is to prevent the cooling water from splashing upward and droplets getting over the flange when the cooling water is atomized in the vicinity of the injection outlet.

In the cooling equipment for the H-section steel configured as described above, in order to set the pair of porous jet devices 5 between the side guides of s and the outer surface of the flange in accordance with the flange width of the H-section steel 1. The side guide 4 itself has the cooling water injection hole 3 because it is close to or away from the flange 2 that is the object to be cooled. Even if the steel 1 contacts, the nozzle will not be damaged.
Furthermore, since the pitch of the cooling water injection holes 3 can be arbitrarily selected, cooling at a high water density, for example, 1000 to 3000 L / min m ² can be easily realized.

FIG. 3 is an explanatory diagram for explaining the equipment layout at the time of manufacturing the H-section steel of this embodiment.
As shown in FIG. 3, a slab having a thickness of 250 mm is heated to 1250 ° C. in a heating furnace, then sent to a breakdown mill and rolled into a H-shaped steel shape material, and then reverse-rolled by a roughing mill 21. Control rolling is performed in which the dimensions of each part of the H-shaped steel are rolled and rolled at a specific reduction rate in a specific temperature range.
Then, the H-shaped steel after the rough rolling was immediately sent to the finishing mill 22 and subjected to rolling with the flanges standing vertically, and finishing rolling was completed at about 800 ° C.
Immediately after that, it was sent to the flange cooling facility 23 of this embodiment shown in FIGS. 1 and 2, and the flange outer surface was cooled to perform accelerated cooling. Thereafter, the temperature distribution in the flange width direction of the H-section steel is measured with the thermometer 24, and further, the hot sawing machine 25 performs sawing.

In this example, after the hot finish rolling, the H-section steels 1a, 1b, and 1c shown in Table 1 below, that is, the H-section steel 1 having flange widths of 200 mm, 300 mm, and 400 mm are used as the flange according to the first embodiment of the present invention. After feeding to the cooling equipment 23 and supplying cooling water to the flange outer surface of the H-shaped steel and cooling with the flange cooling equipment 23, the temperature distribution in the flange width direction of the H-shaped steel 1 is measured with the thermometer 24. Further, the product is manufactured by cutting with a hot sawing machine 25.
The flange cooling facility 23 cools the flange 2 of the H-section steel 1 by supplying cooling water of the perforated jet perpendicularly to the outer surface of the flange 2 of the H-section steel 1 from the pair of perforated jet devices 5. .

By the accelerated cooling by the porous jet of the pair of porous jet devices 5, the surface temperature of the center portion of the flange of the H-section steel 1 becomes about 800 ° C to 640 ° C. As a result, the ferrite structure of the H-shaped steel cross section is refined and the strength is increased.
In addition, the accelerated cooling determined the number of steps of the divided headers 7 </ b> A to 7 </ b> C to be used according to the flange width of the H-section steel 1. In the H-section steel 1a, one header 7C at the bottom is used, in the H-section steel 1b, two headers 7A and 7B, and in the H-section steel 1c, three headers 7A to 7C are used. Based on the flange thickness and the strength target of the product and the conveyance speed of the H-section steel 1, the length of the flange cooling equipment 23 to be used was determined.

The pair of perforated jetting devices 5 of the flange cooling equipment 23 is a box type that slides on the table roller 4, and cooling water was not supplied to the lowermost portion 20 mm of the flange outer surface of the H-section steel 1. In any case of the H-section steels 1a, 1b, and 1c, no cooling water was supplied to the uppermost 20 mm of the outer surface of the flange.
In any case of the H-section steels 1a, 1b, and 1c, after finishing rolling with the temperature distribution in the flange width direction being almost constant 800 ° C., until the center of the flange reaches about 640 ° C. by the pair of porous jet devices 5 Cooling was performed.

FIG. 4 is a graph showing the ratio of the cooling water flow density to three H-section steels having different sizes from the conventional H-shaped steel cooling equipment of Examples 1 to 3, and FIG. FIG. 6 is an explanatory diagram showing the temperature distribution of three H-section steels having different sizes obtained with respect to the ratio of the flow density of the cooling water of the shape steel and the cooling water of the conventional example. It is explanatory drawing which shows the temperature distribution of three H-shaped steel from which the magnitude | size obtained with respect to the ratio of the flow density of the cooling water of the cooling equipment of H-shaped steel differs.
The flow rate distribution in the flange width direction is shown in FIG. 4, but in the conventional example, as shown in FIG. 4A, the flow rate distribution is made constant except for the flange upper and lower ends of 20 mm. The flow rate density of the cooling water at this time is 1000 L / min m ² .
Using this as a comparative example, the flange temperature and product strength evaluation measured after cooling and before hot sawing were compared with Examples 1-3 of the present invention.

In Example 1, as shown in FIG. 4B, the flow density of the cooling water in the block which is the lowermost part of the lowermost header 7C, that is, the cooling water supply unit 10 of 20 to 40 mm from the lower end of the flange is changed to the other. When the block which is the cooling water supply unit 10 is 1500 L / min m ² , it is 1.5 times that.
In addition, the flow rate density of the block that is the cooling water supply unit 10 that is 20 to 40 mm from the top of the header 7A at the third stage from the bottom, that is, the flange upper end of the flange width 400 mm material, 1.5 times.

In the second embodiment, as shown in FIG. 4 (c), in addition to the first embodiment, the uppermost 20 mm cooling water supply unit 10 of the header 77C, 7B from the bottom and the second stage from the bottom is a block. The flow density was also set to 1.5 times that of the other cooling water supply unit 10 block.
In the third embodiment, as shown in FIG. 4 (d), in addition to the second embodiment, a block that is the cooling water supply unit 10 at the bottom 20mm of the second and third headers 7B and 7A from the bottom. The flow density was set to 0.8 times that of the other cooling water supply unit 10.

  The adjustment of the flow rate density of the cooling water is such that the divided headers 7A to 7C are divided into the upper, middle, and lower three blocks 11a to 11c, and the flow rate is controlled independently for each block. This is done by adjusting the degree of opening and closing of the regulating valve 12.

  In the comparative example, the cooling water was not supplied to the upper and lower ends 20 mm of the H-section steels 1a, 1b, and 1c, resulting in a concave temperature distribution as shown in FIG. The temperatures at the center of the flange were 638 ° C., 645 ° C., and 633 ° C., respectively, whereas the temperature maximum values at the upper and lower ends of the flange were very high as shown in Table 2. In either case, the strength at the maximum temperature was not sufficient, so the strengthening element was added, and the cost was inevitably increased.

On the other hand, in Example 1, since the flow density of the block which is the cooling water supply unit 10 of 20 to 40 mm from the lower end of the flange is 1.5 times that of the block which is the other cooling water supply unit 10, this part is compared. It cooled well and became as shown in FIG. The peak value of the flange lower end temperature decreased in any of the H-section steels 1a, 1b, and 1c due to thermal diffusion during cooling and immediately after cooling.
Furthermore, in the H-section steel 1c, since the flow density of the block that is the cooling water supply unit 10 of 20 to 40 mm from the upper end of the flange is 1.5 times that of the block that is the other cooling water supply unit 10, this portion is also relatively It cooled well and the peak value of the flange upper end temperature decreased due to thermal diffusion, which was improved as shown in Table 2 below.
The temperature maximum value of the flange upper ends of the H-section steels 1a and 1b did not decrease. In 1a and 1b, the strength at the maximum temperature portion was not sufficient, but it was improved over the comparative example and the addition of reinforcing elements could be reduced. Further, in 1c, the addition of the reinforcing element can be remarkably reduced, and the cost can be greatly reduced.

In the second embodiment, in addition to the first embodiment, the flow density of the block, which is the cooling water supply unit 10 of the uppermost 20 mm of the header 7C, 7B in the lowest stage and the second stage from the bottom, is also the other cooling water supply unit 10. Since this block is 1.5 times larger than this block, this portion is also cooled more than before, and is as shown in FIG. The peak values of the flange upper end temperatures of the H-shaped steels 1a and 1b were lower than those in the comparative example and Example 1 as shown in Table 2 above.
In the H-section steels 1b and 1c, there was a portion where the flow density of the cooling water increased even near the center of the flange. However, since there was thermal diffusion near the upper and lower portions, supercooling of the strongly cooled portion was slight.
In any of the H-section steels 1a, 1b, and 1c, the addition of the strengthening element can be remarkably reduced, and the cost can be greatly reduced.

In the third embodiment, in addition to the second embodiment, the flow density of the block which is the cooling water supply unit 10 at the lowermost part 20 mm of the headers 7A and 7B other than the lowermost stage is set to 0 of the block which is the other cooling water supply unit 10. 8 times. The cooling of this part is somewhat relaxed and heat is diffused to the adjacent part, that is, a slight supercooled part near the center of the flange, so that the temperature uniformity in the flange width direction can be improved as shown in FIG. did it.
The temperature maximum values at the upper and lower ends of the flange were improved as shown in Table 2 above. As in Example 2, the addition of the strengthening element can be remarkably reduced in any of the H-section steels 1a, 1b, and 1c, and the cost can be greatly reduced.

In Examples 1 to 3, the temperature maximum values at the upper and lower ends of the flange were lower than in the comparative example, and the strength was increased. Conventionally, the steel composition was designed based on the low strength of the flange end. However, since the uniformity in the flange width direction was improved, the addition of reinforcing elements could be reduced. In particular, the effect in Example 2 and Example 3 was great.
In the embodiment of the present invention, the flow rate density of the cooling water is adjusted so that the divided headers 7A to 7C are divided into the upper, middle, and lower three blocks 11a to 11c, respectively. However, the present invention is not limited to this.

As other methods for adjusting the flow density of the cooling water, for example, a large number of injection nozzle holes have the same hole diameter on the entire surface, and when increasing the flow density, the interval between the holes is shortened, and when decreasing the flow density, The flow rate may be adjusted by increasing the interval.
Further, the flow rate density may be adjusted by changing the hole diameter of the injection nozzle hole with the same arrangement.
Furthermore, if the ratio of the injection flow rate density of the injection nozzle holes is the same as the ratio of the nozzle hole area, it is not necessary to adjust the injection pressure, and cooling water can be supplied from the same header. It is.

Moreover, in the Example of this invention, although the non-cooling part of the upper and lower ends is 20 mm and the strong cooling part inside is 20 mm, both are 15-30 mm, and should just be comparable.
If the non-cooled portion is narrower than 15 mm, the cooling water may jump over the upper end of the flange and the cooling water may get on the web. If the non-cooled portion is wider than 30 mm, the effect of lowering the temperature maximum value at the flange end due to thermal diffusion after strong cooling is reduced.

Although the water density of the strong cooling section is 1.5 times that of the normal cooling section, it may be 1.2 to 2.5 times. If it is less than 1.2 times, the effect when compared with the prior art becomes small. If it is larger than 2.5 times, the portion is overcooled and the strength exceeds the allowable upper limit.
In the case of performing weak cooling that has the effect of reducing the effect of strong cooling except at the end of the flange, the water density is 0.8 times that of the normal cooling part, but it may be 0.5 to 0.8 times. If the flow rate is too small, a temperature maximum occurs at that portion, resulting in insufficient strength. If it is larger than 0.8 times, it is almost the same even though weak cooling is not performed.

  The headers 7A to 7C have been described as being used in the case where the flange width of the H-section steel 1 is 200 mm, 300 mm, and 400 mm, and one stage, two stages, and three stages are used. However, the present invention is not limited to this, and is manufactured. It may be divided in any way depending on the type of flange width to be performed. For example, when the product flange width increases from 150 mm to 50 mm pitch, the header may be divided more finely.

It is sectional drawing which shows the structure which has arrange | positioned small H-section steel to the cooling device of H-section steel of Embodiment 1 of this invention. It is sectional drawing which shows the structure which has arrange | positioned medium H-section steel to the cooling device of the same H-section steel. It is explanatory drawing which shows arrangement | positioning of the H-section steel manufacturing equipment which has the cooling equipment of the same H-section steel. It is a graph which shows the ratio of the flow density of the cooling water with respect to three H-section steels from which the magnitude | size of the cooling equipment of the H-section steel of Example 1- Example 3 and a conventional example differs. It is explanatory drawing which shows the temperature distribution of three H-section steel from which the magnitude | size obtained with respect to the ratio of the flow density of the cooling equipment of the H-section steel of Example 1 and the cooling water of a prior art example differs. It is explanatory drawing which shows the temperature distribution of three H-section steel from which the magnitude | size obtained with respect to the ratio of the flow density of the cooling water of the cooling equipment of the H-section steel of Example 1 and Example 2 differs.

Explanation of symbols

1 H-section steel, 2 flange, 3 web, 4 table roller, 5 multi-hole jet apparatus, 6 partition wall, 7A-7C header, 8 side guide, 9 injection nozzle hole, 10 cooling water supply part, 11a-11c block, 12 Flow control valve, 13 on / off control valve, 23H section steel cooling equipment.

Claims (7)

In the H-section steel cooling facility that performs water cooling of the outer surface of the flange by a pair of perforated jet devices arranged so as to sandwich the flange of the H-section steel after hot rolling,
Each of the perforated jet devices includes a plurality of headers arranged in the flange width direction of the H-shaped steel, each having a plurality of injection nozzle holes for supplying cooling water,
The header arranged at the bottom is designed to supply the cooling flow rate of 1.2 to 2.5 times the spray flow density of the 15 to 30 mm portion at the lower end of the many spray nozzle holes as compared to other portions. H-section steel cooling equipment.   In at least one or more of the plurality of headers, the coolant flow rate of 1.2 to 2.5 times that of the other portion of the injection flow density of the 15 to 30 mm portion of the upper end of the injection nozzle hole is supplied. The cooling equipment for H-section steel according to claim 1, characterized in that:   In at least one or more of the plurality of headers excluding the lowermost stage, the injection flow density of the portion of 15 to 30 mm at the lower end of the injection nozzle hole is 0.5 to 0.8 times that of the other portions. The H-section steel cooling equipment according to claim 2, wherein the equipment is supplied.   The adjustment of the injection flow density of the injection nozzle hole is performed by changing the opening / closing degree of a flow adjustment valve provided in a pipe for supplying cooling water to the injection nozzle hole. The H-shaped steel cooling equipment described.   The H-shaped steel cooling equipment according to any one of claims 1 to 3, wherein the adjustment of the injection flow density of the injection nozzle holes is performed by changing the hole areas of the injection nozzle holes.   The H-section steel cooling equipment according to any one of claims 1 to 3, wherein the adjustment of the injection flow density of the injection nozzle holes is performed by making the intervals between the injection nozzle holes different. A method for cooling an H-section steel, comprising cooling the flange of the H-section steel using the H-section steel cooling facility according to claim 1.

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