JP3241806B2 - Cooling method for section steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cooling of a shaped steel, for example, an H-shaped steel manufactured by hot rolling and the like. And TMCP (Ther
It proposes a cooling method for shaped steel that is advantageous for application to mo-Mechnical Control Process).

[0002]

2. Description of the Related Art Conventionally, cooling of an H-section steel is generally performed by cooling an outer surface of a flange for the purpose of preventing generation of a web wave. For example, Japanese Patent Application Laid-Open No. 60-221524 discloses a method of cooling an H-section steel. A means for water cooling the outer surface of the flange using a flange cooling nozzle has been proposed and disclosed in the flange cooling device.

Further, in order to prevent the bending of the H-section steel, a means for cooling the inner surface of the lower flange by spraying cooling water has been proposed and disclosed in Japanese Patent Application Laid-Open No. 52-104451.

On the other hand, the collection of lectures of the Iron and Steel Institute of Japan VoL 73 No4 8
According to “Creation of heat deformation model and application to shaped steel” disclosed in 7-S290, it is shown that flange warpage and squareness can be improved and controlled by cooling the upper and lower surfaces (outer and inner surfaces) of the flange.

[0005] However, the cooling condition is that the upper surface water cooling is 3
If the water volume density is relatively low at 00l / m ² · min and the water cooling stop temperature is near the MS point temperature, the temperature difference between the inner and outer surfaces of the flange is 7
It can be estimated as 0 to 80 ° C.

Also, it is understood that if the difference in the water density between the cooling water jets on the inner and outer surfaces of the flange is reduced, the temperature difference in the flange plate thickness direction is reduced and the flange warpage is necessarily reduced. No consideration is given to the temperature difference between the inner surface and the outer surface of the flange, which is the limit of warpage. Further, in the above experiment, the flange was in a horizontal position, and the web temperature drop due to the flow of the inner surface cooling water that would occur in the case of the horizontal position of the web, such as the H-section steel before and after rolling, was not considered. Not touched.

[0007]

In the case of H-section steel, the temperature difference between the flange and the web increases during cooling as the web becomes thinner and the flange thickness increases, and the residual stress caused by this temperature difference exceeds the limit. Then, buckling called a web wave occurs in the web portion. Therefore, as described above, the cooling from the outer surface of the flange is strengthened and the temperature difference between the flange and the web is reduced.However, since the cooling is performed on one side, the temperature difference in the flange plate thickness direction, that is, the inner surface and the outer surface of the flange. When the temperature difference is large and the stress generated by this temperature difference exceeds the limit, the flange is bent toward the web side from the junction between the flange and the web after cooling to room temperature (when the flange inner surface temperature is higher), it is called flange warpage. Shape defects occur.

If the temperature of the inner and outer surfaces of the upper and lower flanges and the left and right flanges of the H-section steel in which the web is horizontal is different, the bent shapes of the upper and lower flanges and the left and right flanges may be different. Poor squareness may occur.

FIG. 1 is an explanatory view of the warpage of the flange of the H-section steel, and FIG. 2 is an explanatory view of the perpendicularity of the H-section steel. In FIG. 1, (a) shows a case where the flange is warped by bending to the outer surface of the flange, and (b) shows a case where the flange is warped by bending to the web side. Flange warpage represents V or R (R _1, R ₂₎ shown in FIG. 1, perpendicularity represented by T as shown in FIG. In these figures, 11A is the web, 11A
B is a flange.

In order to prevent the occurrence of the above-mentioned shape defect,
The above-mentioned means for water-cooling only the inside of the lower flange, whose main purpose is to change the H-roll angle (draft) of rough rolling and finish rolling, and to prevent bending, has some effects, but is insufficient. It is currently corrected by the machine.

In the above-mentioned Japanese Patent Application Laid-Open No. 52-104451, water cooling on the inner surface of the flange is limited to the lower portion of the flange. Despite the fact that it is important to reduce the temperature difference between the flange and the web in order to reduce the residual stress, the web surface is cooled because it gets on the surface,
This is because he was concerned that the opposite result would occur.

Accordingly, the present invention advantageously solves the above-mentioned problems, and can be applied to a thin-walled web, a flange plate having a large thickness, or a case where the target finishing temperature at the end of water cooling is lowered. It is an object of the present invention to provide a cooling method capable of suitably performing control and obtaining an H-shaped steel having a good shape without causing not only a web wave but also a flange warp and a squareness defect.

[0013]

The present invention focuses on the temperature difference between the outer surface of the flange and the inner surface of the flange to be air-cooled when the outer surface of the flange is water-cooled. Deriving the allowable temperature difference between the inner and outer surfaces of the flange, adding water cooling to both inner surfaces of the flange sandwiching the web surface, and taking into account the temperature drop of the web due to the cooling of the inner surface of the flange, so that the web wave does not occur This is because water-cooling conditions for obtaining an H-shaped steel having a good shape without flange warpage, poor flange perpendicularity, and web undulation by controlling the average temperature difference between the flange and the flange have been found.

That is, the gist of the present invention is to cool a shaped steel having a web and a pair of flanges sandwiching the web, which is conveyed at a high temperature, by injecting cooling water from the inner surface and the outer surface of the flange. At this time, the temperature difference between the inner and outer surfaces of the flange is within an allowable range where the warpage of the flange does not occur, and the average temperature of the web and the flange taking into account the temperature drop of the web determined by the amount of cooling water injected and supplied to the inner surface of the flange. By adjusting the supply amount of cooling water injection to the inner surface of the flange and the outer surface of the flange so that the difference falls within the allowable range where the web wave does not occur, the occurrence of the web wave, the warpage of the flange and the squareness defect is prevented. The cooling method for the shaped steel

[0015] In the above method for cooling a section steel, the limit stress value at which flange warpage does not occur or the temperature difference between the inner surface of the flange and the outer surface of the flange at the end of water cooling, and the limit at which web waves do not occur, for each size of the section steel. Water cooling conditions to determine the residual stress value or the average temperature difference between the web and the flange at the end of water cooling in advance, and adjust the amount of water supplied for cooling water injection for each of the inner and outer surfaces of the flange to make the water flow below the predetermined value A method for cooling a shaped steel, characterized in that:

A plurality of cooling water nozzles having a raising and lowering function are used to cool a high-temperature section steel having a web and a pair of flanges sandwiching the web, which is conveyed to keep the web horizontal, by cooling water injection. A cooling zone consisting of one or more cooling banks arranged in multiple stages in the flange width direction facing the flange inner surface and the flange outer surface facing each other in the upper and lower direction and in the shape steel feeding direction is provided in the shape steel feeding direction. A plurality of bases are arranged along the inner surface of the flange, the temperature distribution on the inner surface of the flange and the outer surface of the flange, and the inner surface of the flange and the outer surface of the flange facing each other above and below the cooling bank and the web based on the average temperature of the web, respectively. the coolant nozzle elevating adjusting cooling method H-beams, characterized in that for selecting the injection of the cooling water for each placement stage of the cooling water nozzles <br/> Ru Oh.

[0017]

[0018]

The present invention relates to a flange inner surface and a flange facing each other above and below a horizontally maintained web in order to obtain a temperature difference between an outer surface and an inner surface of a flange in which flange warpage does not occur for each flange plate thickness. The outer surface and the outer surface of the flange shall be cooled by estimating the temperature drop of the web due to the water cooling of the inner surface of the flange. The main requirement is to set the water cooling conditions for each section.Thus, the thin section web, the flange plate thickness is large, the finishing temperature at the end of water cooling is low, etc. An object of the present invention is to obtain an H-shaped steel having a good shape without a flange warpage, a flange perpendicularity defect and a web wave by making the temperature distribution uniform.

Hereinafter, experimental examples and examination results will be described. The relationship between the warpage of the flange and the temperature difference between the inner surface and the outer surface of the flange was investigated for an H-section steel of size 500 × 200. As a result, it was found that when the flange thickness was 16 mm or more, the flange warpage increased when the temperature difference exceeded 150 ° C. When the plastic deformation limit stress at which flange warpage does not occur is calculated by the temperature, shape, and deformation program, the plastic deformation limit stress caused by the temperature difference between the inner surface and the outer surface of the flange is 5-8.
It was found to be Kgf / mm ² .

Here, the plastic deformation limit stress is 5.6 kgf / mm ²
FIG. 3 shows a calculation result of the relationship between the flange plate thickness and the deformation limit cooling capacity (heat transfer coefficient α) in which flange warpage does not occur when one-side water cooling (flange outer surface water cooling) is performed. In this figure, the deformation limit cooling capacity based on the off-line experimental results is also shown.

As can be seen from FIG. 3, the deformation limit cooling capacity decreases as the flange plate thickness increases. In other words, in order to cool the flange only by water cooling on the outer surface without causing flange warpage, the cooling capacity must be reduced by reducing the injection amount of cooling water as the flange plate thickness increases, and sufficient cooling is required. When the target temperature at the end of water cooling is set low, or when the thickness of the web is promoted, it cannot be applied.

Therefore, in order to control the temperature between the inner surface and the outer surface of the flange, it is important to combine the water cooling of the inner surface in addition to the water cooling of the outer surface of the flange. Control becomes easy, and the target temperature after water cooling can be set low, so that a wide range of target temperature can be set.

For this reason, when the inner and outer surfaces of the flange facing each other above and below the horizontally maintained web are water-cooled, for example, the simulation model taking into account the existing H-section steel rolling line is used. Water cooling conditions to reduce the generated residual stress and to reduce the flange warpage and squareness were studied, and the equipment arrangement of the water cooling zone was determined.

FIG. 4 is an explanatory view of the arrangement of the rolling line and the water cooling zone according to the above. In the figure, U ₁ is a rough rolling mill, E
₁ edger, U _F is the finishing machine, 1-1, 1-2, 1-
3 is cooling zone 1, 3-1 and 3-2 are cooling zones 3 and 4-1,
4-2 is each bank of the cooling zone 4. The rough rolling mill shaped steel through the edger E ₁ from U ₁ is cooling zone 1, after being cooled by air cooling section (not shown) and a cooling zone 3, the final in a cooling zone 4 through the rolling by the finishing mill U _F Water cooling is performed.

In this figure, in the cooling zone 1, only the outer surface of the flange is water-cooled, and in consideration of the temperature movement in the flange plate thickness direction due to the recuperation process of the water-cooled surface in the air cooling section between the cooling zones 1 and 3, the cooling zone 3 is cooled. From the temperature distribution on the inlet side and the outlet side of the cooling zone 4, the injection supply water amount for each flange inner surface position is determined, and the average temperature difference between the flange and the web in consideration of the temperature drop of the web due to the injection supply water is determined by a predetermined value. The water supply condition was calculated by taking in the amount of injection supply water on the outer surface of the flange. Naturally, a scanning thermometer is installed on the exit side of each water cooling zone so that the temperature can be learned in order to improve the calculation accuracy.

In the water cooling zones 3 and 4, the cooling water is injected to the inner and outer surfaces of the flange, and the inner and outer surfaces can be simultaneously injected or the inner or outer surface can be selectively injected for each bank. Although the number of banks is two in the figure, it goes without saying that increasing the number of banks increases the degree of freedom in selecting a water cooling pattern.

Next, the calculation logic for determining the water cooling condition will be described with reference to FIG. FIG. 5 is an explanatory diagram of calculation logic for determining a water cooling condition.

In this figure, first, the water cooling condition of the outer surface of the flange is determined from the size of the section steel, the flange temperature distribution and the web temperature distribution before water cooling, and a predetermined target finishing temperature (the average temperature of the flange and the web at the end of water cooling). Is provisionally determined. In the provisional determination of the water cooling conditions, the used cooling zone, the used bank, the arrangement stage of the used nozzles, the injection water supply amount, and the like are determined in advance by the conveying speed of the shaped steel.

The temperature difference between the inner and outer surfaces of the flange at the end of water cooling of the shaped steel obtained by water cooling under the provisionally determined water cooling conditions is 120 ° C. or less, or the flange surface stress after cooling to room temperature is the critical stress. 5.6 kgf / mm ² or less (Although not shown, the average temperature difference between the web and the flange and the web surface stress after cooling to room temperature are also less than the allowable limit set in the same way), and If the finishing temperature satisfies the target value, the provisionally determined water cooling condition is determined as it is as the actual water cooling condition.

However, in the case of a thin-walled web, a thick flange plate, or a low finishing temperature at the end of water cooling, the temperature difference between the outer and inner surfaces of the flange, the stress on the flange surface, or the difference between the web and the flange. The average temperature difference or web surface stress may exceed the above-mentioned allowable limit. In this case, it is necessary to combine the flange inner surface water cooling which is a feature of the present invention, and the flange inner surface water cooling condition is determined by calculation, and water cooling is performed in addition to the tentatively determined water cooling condition (flange outer surface water cooling).

With respect to the section steel obtained by water cooling combined with the water cooling of the inner surface of the flange, the temperature difference between the outer surface and the inner surface of the flange or the stress on the flange surface and the average temperature difference between the web and the flange or the stress on the web surface are not more than the above set values. ,And,
If the finishing temperature satisfies the target value, the above conditions are determined as actual water cooling conditions.

However, when the above-described water cooling of the flange inner surface is added, the cooling water inevitably lowers the web temperature, so that the average temperature difference between the web and the flange or the finishing temperature does not satisfy the target values. Often. As described above, if the average temperature difference between the web and the flange or the finishing temperature does not satisfy the target values by simply combining the water cooling on the inner surface of the flange, the temperature drop in the web portion is taken into consideration, and Review and correct the provisionally determined flange outer surface water cooling conditions, and perform the same operation as above. These steps are repeated until optimum water cooling conditions are found.

By cooling using the water cooling conditions determined as described above, it is possible to obtain a shaped steel having a good shape free from web undulations, poor flange warpage, and the like.

[0034]

【Example】

Embodiment 1 A cooling bank suitable for the present invention will be described. FIG. 6 is an explanatory view of a cooling bank according to the present invention. Hereinafter, description will be made with reference to FIG. Although the cooling bank is mounted facing both flanges, FIG. 6 shows only one side.

The nozzle for water cooling the inner surface of the flange of the section steel 11 is composed of an upper inner surface water cooling nozzle 26-1 and a lower inner surface water cooling nozzle 26-2, which are two-steps in the flange width direction and in the feed direction of the section steel 11. Are arranged in series, and are connected to the respective inner surface nozzle headers 28 via the respective nozzle hoses 16 for each nozzle arrangement stage, so that the cooling water can be jetted or stopped for each nozzle arrangement stage. Has become. The number of the arrangement steps may be changed according to the flange width.

The upper inner water cooling nozzle 26-1 is mounted via an inner nozzle lift lever 25, an inner nozzle lower elevating beam 23, an upper inner nozzle guide carriage 20, and an upper inner nozzle support 30, and connected to the lift lever 25. It can be moved up and down by driving the inner surface nozzle elevating motor 24.
Further, the upper inner water cooling nozzle 26-1 is
-Inner nozzle support 30 so that the interval with -2 can be adjusted
It can also be raised and lowered by an upper inner surface nozzle raising / lowering motor 29 attached to the motor.

The lower inner water cooling nozzle 26-2 is mounted via a lift lever 25, an inner nozzle lower elevating beam 23, and a lower inner nozzle guide carriage 21. The inner nozzle elevating motor 24 connected to the lift lever 25 is driven. To go up and down. Accordingly, the upper inner water cooling nozzle 26-1 and the lower inner water cooling nozzle 26-2 are simultaneously moved up and down by the driving of the inner nozzle elevating motor 24 at the same time.

Next, the outer surface water cooling nozzle 13 of the flange is
In the case of the inner surface, three stages are arranged in the flange width direction and a plurality of stages are arranged in the feed direction of the shaped steel 11, and connected to each outer surface nozzle header 15 via each nozzle hose 16 for each nozzle arrangement stage. In the same manner as described above, the cooling water can be injected or stopped for each arrangement stage of the nozzles. The number of nozzles arranged may be changed according to the flange width.

The outer surface water-cooling nozzle 13 is attached to an outer surface nozzle mounting support 14 connected to an outer surface nozzle mounting support elevating motor 17 provided on the outer surface nozzle loading guide 12 so as to be movable up and down.

On the other hand, the upper inner nozzle guide truck 20 and the lower inner nozzle guide truck 21 are connected by a bogie connecting shaft 22. Further, an inner / outer nozzle guide connection block 19 is provided on the upper / inner nozzle guide carriage 20 and is connected to an inner / outer nozzle guide interval adjusting motor 18 provided on the outer nozzle loading guide 12 to provide an upper / inner water cooling nozzle 26-1. The distance between the lower inner water cooling nozzle 26-2 and the outer water cooling nozzle 13 can be adjusted.

By using the cooling bank as described above, the distance between the upper inner water cooling nozzle 26-1 and the lower inner water cooling nozzle 26-2 and the outer water cooling nozzle 13 is adjusted according to the thickness of the flange of the shaped steel 11. They can be adjusted, and they can be moved in the flange width direction, and the cooling water can be sprayed or stopped at each nozzle arrangement stage, so that the movement can be adjusted according to the flange width and the sectional steel section temperature distribution is taken into consideration. By selecting the nozzle arrangement stage to be used, the cooling water can be sprayed from the inner surface and the outer surface of the flange to a suitable position.

Example 2 Using a steel type SM490 as a material, a cooling zone having a cooling bank shown in FIG. 6 and a cooling zone 3 shown in FIG.
And H, the H-shaped steel H
-550 x 200 x 6 x 16 and H-550 x 200 x 9 x 22
Rolling the size and cooling it with water cooling only on the flange outer surface of the conventional method (comparative example) and cooling it under water cooling conditions compatible with the present invention combining flange outer water cooling and flange inner water cooling (fit example) The temperature of the outer and inner surfaces of the flange after water cooling and the amount of flange warpage of the H-section steel (product) were investigated. Table 1 shows these water cooling conditions, and Table 2 shows the investigation results.

[0043]

[Table 1]

[0044]

[Table 2]

As is clear from Table 2, in the comparative example in which the conventional cooling was performed, there is no problem when the temperature after water cooling is relatively high, but when the temperature is cooled to a lower temperature, the temperature difference between the outer surface and the inner surface of the flange is reduced. And the amount of flange warpage naturally increases. On the other hand, the adaptation according to the present invention has a small flange warpage even when cooled to a low temperature, and the effect of the present invention is clearly shown. In addition, there was no occurrence of a web wave or a squareness defect in all the samples.

[0046]

According to the present invention, in cooling a section steel under high-temperature transportation, a water cooling condition is set by combining water cooling on the inside of the flange and water on the outside of the flange in consideration of the web temperature drop due to water cooling on the inside of the flange. According to the present invention, the temperature difference between the inner surface and the outer surface of the flange can be reduced even when the finishing temperature at the end of water cooling is lower, and the shape of the shape can be improved. Steel can be obtained, which can not only cope with further thinning of the web of H-section steel for SRC (Steel Reinforced Concrete), but also
Application to the production of shaped steel using MCP is also advantageous.

[Brief description of the drawings]

FIG. 1 is an illustration of flange warpage of an H-section steel. (a) is an explanatory view in the case where the flange is bent to the outer surface side and the flange is warped. (b) is an explanatory view in the case where a flange is warped due to bending on the web side.

FIG. 2 is an explanatory view of a right angle of an H-section steel.

FIG. 3 is a graph showing the relationship between the flange plate thickness when the flange outer surface is water-cooled and the deformation limit cooling capacity (heat transfer coefficient α) in which flange warpage does not occur.

FIG. 4 is an explanatory diagram showing an arrangement of rolling lines and water cooling zones.

FIG. 5 is an explanatory diagram of calculation logic for determining a water cooling condition.

FIG. 6 is an explanatory view of a cooling bank according to the present invention.

[Explanation of symbols]

1 cooling zone 1-1, 1-2, 1-3 cooling bank 3 cooling zone 3-1, 3-2 cooling bank 4 cooling zone 4-1, 4-2 cooling bank 11 H-section steel 11A web 11B flange 12 outer surface Nozzle loading guide 13 External water cooling nozzle 14 External nozzle mounting support 15 External nozzle header 16 Nozzle hose 17 External nozzle mounting support elevating motor 18 Motor for adjusting internal / external nozzle guide spacing 19 Internal / external nozzle guide connection block 20 Upper internal nozzle guide Dolly 21 Lower inner nozzle guide trolley 22 Bogie connection shaft 23 Inner nozzle lower elevating beam 24 Inner nozzle elevating motor 25 Inner nozzle lift lever 26-1 Upper inner water cooling nozzle 26-2 Lower inner water cooling nozzle 28 Inner nozzle header 29 Upper Inner nozzle elevating motor 30 Upper inner nozzle support U ₁ Rough rolling mill E Edger U _F finishing rolling mill

Claims (3)

(57) [Claims] In cooling a shaped steel having a web and a pair of flanges sandwiching the web and conveyed at a high temperature by cooling water injection, cooling water is injected from an inner surface of the flange and an outer surface of the flange. The average temperature difference between the web and the flange, taking into account the temperature drop of the web determined by the amount of cooling water injected and supplied to the inner surface of the flange, as the temperature difference between the inner and outer surfaces falls within the allowable range where flange warpage does not occur, generates a web wave The cooling of shaped steel is characterized by preventing the occurrence of web waves and the occurrence of flange warpage and squareness defects by adjusting the amount of cooling water supplied to the inner and outer surfaces of the flange so as to fall within the allowable range. Method. 2. The method for cooling a shaped steel according to claim 1, wherein, for each size of the shaped steel, a critical stress value at which flange warpage does not occur or a temperature difference between an inner surface of the flange and an outer surface of the flange at the end of water cooling, and The average residual temperature difference between the web and the flange at the end of the water cooling or the critical residual stress value at which the web wave does not occur is determined in advance, and the supply water amount of the cooling water injection is adjusted for each of the inner surface of the flange and the outer surface of the flange. A method for cooling a section steel, characterized by determining water cooling conditions of not more than a value. 3. A plurality of cooling water nozzles having a web and a pair of flanges sandwiching the web and having a function of elevating and lowering when cooling a high-temperature section steel being conveyed for maintaining the web horizontally by jetting cooling water. A cooling zone consisting of one or more cooling banks arranged in multiple stages in the flange width direction facing the flange inner surface and the flange outer surface facing each other on the upper and lower sides of the web and in the shape steel feeding direction is provided. A plurality of bases are arranged along the feed direction. Based on the temperature distribution on the inner and outer surfaces of the flange and the average temperature of the web, the inner and outer surfaces of the cooling zone, the respective cooling banks, and the upper and lower flanges facing each other at the upper and lower sides of the web. A cooling water nozzle is raised and lowered, and cooling water is selectively jetted for each stage of disposing the cooling water nozzle.