JP2010064097A - Cooling apparatus of steel material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for uniformly cooling a hot steel plate at high cooling rate when feeding cooling water to upper and lower surfaces of the hot steel plate. <P>SOLUTION: This invention relates to a steel material cooling apparatus installed on a hot rolling line of steel material, which is provided with a header for feeding cooling water to surfaces of the steel material, a cooling water jetting nozzle extending from the header, and a bulkhead installed between the steel material and the header, wherein the bulkhead is provided with a large number of water feed ports with a fore end of the cooling water jetting nozzle being inserted therein, and a large number of water discharge ports for discharging cooling water fed to the surfaces of the steel material to a back side of the bulkhead, and the water discharge ports are arrayed on circumcenters of triangles consisting of three segments connecting the adjacent water feed ports to each other or bisected points of each ridge of the triangle. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a steel material cooling facility.

  In the process of manufacturing steel plates such as thick plates and thin plates by hot rolling, for example, in equipment as shown in FIG. 15, after hot rough rolling / finish rolling, water cooling or air cooling is performed to control the structure. Yes. When cooling to a relatively low temperature, for example, about 450 to 650 ° C. by water cooling, fine ferrite and bainite structure can be obtained and the strength of the steel sheet can be secured. Therefore, there is a technology for cooling the steel sheet with spray cooling water, laminar cooling water, etc. It is common. In recent years, the development of techniques for increasing the strength of steel sheets by obtaining a high cooling rate and making the structure finer is increasing.

  For example, there are technologies of Patent Document 1 and Patent Document 2 as a technology for cooling a hot steel sheet by supplying a large amount of rod-shaped cooling water. This is one in which cooling water is jetted at high speed from nozzles installed on the upper and lower surfaces of a steel plate, and a very high cooling rate can be obtained and a product excellent in material characteristics can be manufactured.

Moreover, there exists a technique of patent document 3 as another technique which cools a hot-steel plate by supplying cooling water. This is to form a pool by filling the area surrounded by the steel plate, roll and side wall with the cooling water sprayed from the nozzle, and it becomes a steady cooling state and reduces uneven cooling in the width direction. It is supposed to be possible.
JP 2002-239623 A JP 2004-66308 A JP 2006-35233 A

  However, the conventional technique has a problem in securing the cooling capacity and the cooling uniformity.

  In the techniques of Patent Documents 1 and 2, cooling water sprayed from a plurality of cooling nozzles passes through one hole or slit of a protective plate provided between the cooling water header and the hot-rolled steel strip, and The supplied cooling water is discharged from the same hole or slit. That is, since the functions of the injection port and the drainage port coexist, the flow of the cooling drainage flow is reverse to the rod-shaped cooling water sprayed from the nozzle tip as shown in FIG.

  Also, the discharged water after reaching the steel plate rises by colliding with each other, and the flow path is bent until it reaches the drain outlet that is also used as the nozzle port, so this part becomes a stagnation and the discharged water Smooth flow was hindered. Thus, it has been found that the techniques of Patent Documents 1 and 2 have some difficulty in smooth discharge of the cooling water supplied to the steel strip surface. Therefore, in order to ensure that the cooling water reaches the steel plate, a high injection pressure is applied to the header and the cooling water has to be injected at a high speed, resulting in an increase in equipment costs.

  Also, if a slit-shaped hole is made, the part between the slits of the protective plate becomes a thin plate, so the rigidity of this part decreases, and if the warped steel sheet enters the cooling equipment and collides, the equipment is damaged. There is also a risk of doing. Therefore, there is no problem if the thickness of the steel sheet to be cooled is 2 to 3 mm, but if the thickness is 15 mm or more, it is difficult to process the slit because a thick protective plate must be used to prevent equipment damage. There is also.

  Furthermore, when slit-like holes having different sizes are formed, the flow resistance varies depending on the position of the nozzle, and thus there is a problem that uneven cooling temperature occurs in the width direction of the steel sheet.

  The technique of Patent Document 3 has a structure in which the cooling water supplied to the upper surface of the steel plate forms a pool in a space surrounded by the steel plate, the roll, and the side wall, and flows upward. Therefore, there is a problem that the state of the cooling water becomes unsteady within the range of the number of tips of the steel sheet, and uneven cooling temperature and warpage in the longitudinal direction of the steel sheet are likely to occur.

  Moreover, in the technique of patent document 3, although the case where a side wall is not provided is also described, in this case, as shown by a dotted arrow in FIG. 17, the discharged water is directed on the guide plate toward the end in the width direction. Will flow. Here, in the technique of Patent Document 3, since the tip of the cooling nozzle is above the guide plate, the flow in the width direction of the discharged water interferes with the cooling water ejected from the cooling nozzle.

  Since this width direction flow increases at the end in the width direction of the steel sheet, the interference becomes stronger toward the end in the width direction of the steel sheet, and a part or all of the cooling water sprayed from the cooling nozzle cannot reach the upper surface of the steel sheet. Therefore, it is difficult to perform uniform cooling in the width direction.

  In view of the above, an object of the present invention is to provide a technique for uniformly cooling with high heat transfer coefficient when supplying cooling water to the surface of a steel material.

    In order to solve the above problems, the present invention has the following features.

  1st invention is the cooling equipment of the steel materials installed in the hot rolling line of steel materials, Comprising: The header which supplies cooling water to the surface of steel materials, The cooling water injection nozzle extended from the header, The above-mentioned steel materials A partition wall provided between the header and the partition wall. The partition wall includes a water supply port for inserting a tip end portion of the cooling water injection nozzle, and cooling water supplied to the surface of the steel material. There are a large number of drain outlets for draining to the back, and the drain outlets are arranged at a triangle outer center consisting of three line segments connecting the adjacent water inlets or at a bisection point on each side of the triangle It is the cooling equipment of the steel material characterized by being characterized.

  A second invention is a steel material cooling facility installed in a hot rolling line for steel material, a header for supplying cooling water to the surface of the steel material, a cooling water jet nozzle extending from the header, and the steel material. A partition wall provided between the header and the partition wall. The partition wall includes a water supply port for inserting a tip end portion of the cooling water injection nozzle, and cooling water supplied to the surface of the steel material. There are a large number of drain outlets for draining to the back, and the drain outlets are arranged at the center of gravity of a quadrilateral consisting of four line segments connecting the adjacent water inlets or at the bisection point of each side of the square This is a steel material cooling facility.

  3rd invention sets the total cross-sectional area of the discharge port provided in the partition to 1.5 times or more the total cross-sectional area of the cooling water injection nozzle, The steel material according to the 1st or 2nd invention The cooling equipment.

  4th invention makes the clearance gap between the outer peripheral surface of the cooling water injection nozzle inserted in the water supply port provided in the partition and the inner surface of the said water supply port 3 mm or less, The 1st thru | or 3rd invention characterized by the above-mentioned. The steel material cooling facility according to any one of the above.

According to a fifth aspect of the present invention, the cooling water injection nozzle has an inner diameter of 3 to 8 mm, the cooling water injected from the cooling water injection nozzle is a rod-shaped cooling water having a flow rate of 8 m / s or more, and the water amount density is 1.5 to 4. The steel material cooling facility according to any one of the first to fourth inventions, wherein the cooling capacity is 0 m ³ / m ² · min.

By using the steel material cooling equipment of the present invention, it is possible to obtain a high heat transfer coefficient and to reach the target temperature quickly. That is, since the cooling rate can be increased, a new product such as a high-tensile steel plate can be developed. Moreover, since the cooling time of steel materials can be shortened, productivity can be improved by increasing the production line speed, for example.
Furthermore, since it can cool uniformly on the whole injection surface, a high quality steel product can be manufactured.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. Here, the case where the present invention is used for cooling the upper surface of a steel plate in the thick plate rolling process will be described as an example.

FIG. 15 is a schematic view showing an example of a thick plate rolling line used for carrying out the present invention.
The slab extracted from the heating furnace is subjected to rough rolling and finish rolling by a rolling mill to a predetermined finishing temperature and finishing plate thickness, and then conveyed to an accelerated cooling facility online. It is suitable for obtaining a uniform material to perform accelerated cooling after adjusting the shape of the steel sheet through a pre-leveler before cooling. In the accelerated cooling facility, the steel sheet is cooled to a predetermined temperature by the cooling water sprayed from the upper surface cooling facility and the lower surface cooling facility.

  FIG. 1 is a side view showing an arrangement of upper and lower surface cooling facilities when the cooling device of the present invention is applied to an upper surface cooling facility as an example of an embodiment of the present invention.

1 Overview of Top Surface Cooling Facility The top surface cooling facility is a header 1 that supplies cooling water to the top surface of a hot steel plate 12, a cooling water injection nozzle 3 that extends from the header 1, and a steel plate between the header 1 and the hot steel plate 12. A partition wall 5 is installed horizontally across the width direction and has a large number of through holes (water supply port 6 and drain port 7). The cooling water injection nozzle 3 is composed of a circular tube nozzle 3, and its tip is inserted into a through-hole (water supply port 6) provided in the partition wall 5 so as to be above the lower end of the partition wall 5. Has been.

  The circular tube nozzle 3 is installed so that the tip of the circular tube nozzle 3 is inserted into the through-hole and above the lower end of the partition wall 5 even if a steel plate whose tip is warped upward enters. This is to prevent the tube nozzle 3 from being damaged. As a result, the circular tube nozzle 3 can be cooled for a long period of time in a good state, so that it is possible to prevent the occurrence of uneven temperature in the steel sheet without repairing the equipment.

  Further, since the tip of the circular tube nozzle 3 is inserted in the through hole, as shown in FIG. 16, there is no interference with the flow in the width direction of the drained water indicated by the dotted arrow flowing through the upper surface of the partition wall 5. Therefore, the cooling water sprayed from the circular tube nozzle 3 can reach the upper surface of the steel plate equally regardless of the position in the width direction, and uniform cooling in the width direction can be performed.

  As shown in FIG. 3, the partition wall 5 has a large number of through holes having a diameter of 10 mm. A circular pipe nozzle 3 having an outer diameter of 8 mm and an inner diameter of 3 mm is inserted into the water supply port 6. The circular tube nozzles 3 are arranged in, for example, a staggered pattern, and the through holes through which the circular tube nozzles 3 do not pass serve as cooling water drains 7. Thus, the many through holes provided in the partition wall 5 of the cooling facility of the present invention are composed of the many water supply ports 6 and the drain ports 7, and share the role and function of each.

  At this time, although details will be described later, the total cross-sectional area of the drain port 7 is sufficiently wider than the total cross-sectional area of the inner diameter of the circular tube nozzle 3, and the cooling water that has reached the upper surface of the hot steel plate as shown in FIG. The space between the steel plate surface and the partition wall 5 is filled, guided through the drain port 7 to the upper side of the partition wall 5 (on the back side of the partition wall 5 with respect to the steel plate surface), and quickly discharged.

  As shown in FIG. 10, the discharged water 9 guided to the upper side of the partition wall 5 is guided to the outside in the steel plate width direction and drained through the drainage channel between the header 1 and the partition wall 5.

  As shown in FIG. 13, when the drainage port and the water supply port are installed in the same through hole, after the cooling water collides with the steel plate, it becomes difficult to escape above the partition wall 5, and between the steel plate 12 and the partition wall 5. Flows toward the end in the width direction of the steel sheet. Then, since the flow rate of the cooling drainage between the steel plate 12 and the partition wall 5 increases as it approaches the end in the plate width direction, the force that the injected cooling water reaches the steel plate through the staying water film is the end in the plate width direction. It will be hindered.

  In the case of a thin plate, since the plate width is about 2 m at most, the influence is limited. However, in the case of a thick plate having a plate width of 3 m or more, the influence cannot be ignored. Accordingly, the cooling at the end in the width direction of the steel sheet becomes weak, and the temperature distribution in the width direction of the steel sheet in this case becomes a non-uniform temperature distribution having a concave shape as shown in FIG.

  On the other hand, in the cooling facility of the present invention, as shown in FIG. 14, the water supply port 6 and the water discharge port 7 are provided separately and share the roles of water supply and water discharge. The cooling water discharged from the cooling water filled in between passes through the outlet 7 of the partition wall 5 and smoothly flows above the partition wall 5. Accordingly, since the drainage after cooling is quickly removed from the upper surface of the steel sheet, the cooling water supplied subsequently can easily penetrate the staying water film, and a sufficient cooling capacity can be obtained. In this case, the temperature distribution in the width direction of the steel sheet can obtain a uniform temperature distribution in the width direction as shown in FIG.

  The distance between the lower surface of the header 1 and the upper surface of the partition wall 5 is such that the cross-sectional area in the steel plate width direction in the space surrounded by the lower surface of the header 1 and the upper surface of the partition wall 5 is 1.5 of the total sectional area of the inner diameter of the circular tube nozzle 3. It is preferably provided so as to be twice or more, for example, about 100 mm or more. If the cross-sectional area of the flow path in the steel plate width direction is not 1.5 times or more than the total cross-sectional area of the inner diameter of the circular tube nozzle 3, the cooling drainage discharged from the drain port 7 provided in the partition wall 5 smoothly flows in the width direction of the steel plate. This is because it cannot be discharged.

2. Arrangement of Water Supply Port and Drainage Port Next, the arrangement of the water supply port 6 and the drainage port 7 for discharging cooling water more quickly on the partition wall will be described with reference to FIGS. In the figure, 5 indicates a partition wall, 6 indicates a water supply port, 7 indicates a drainage port, and 3 indicates a circular tube nozzle inserted in the water supply port 6.

(A) FIGS. 2-3 is an example which arranged the water supply port 6 in the partition 5 in zigzag.
FIG. 2 is a partial array diagram of the water supply / drainage port illustrating the positional relationship with the water discharge port 7 when the water supply port A is focused. FIG. 3 is a plan view of the partition wall in which the partial arrangement of the water supply / drain ports of FIG. 2 is developed on the partition wall.

As shown in FIG. 2, there are six water supply ports B to G adjacent to the water supply ports A arranged in a staggered manner.
There is one drainage port p1 to p6 at the outer center of a triangle consisting of three line segments connecting the adjacent water supply ports B to G with the water supply port A as the apex (intersection where three perpendicular bisectors of each side intersect). Is provided.

  When the drain outlets are arranged in this way, for example, the drain outlet p1 point has the same distance from the water inlets A, B, C, and the cooling water injected from the water inlets A, B, C collides with the hot steel plate 12, It is a point that diffuses and merges along the surface of the hot steel sheet 12. And since the discharge port p1 was provided at this confluence, drainage onto the partition wall was performed smoothly, and the cooling water steadily reached the surface of the hot steel plate 12 as shown in FIG. Since the cooling capacity and the drainage capacity are the same at all positions, a uniform temperature distribution can be obtained in the steel plate width direction.

  In FIG. 2, the triangle ABC is shown as an isosceles triangle having the same length of the side AB and the side AC. However, the present embodiment is not limited to this. For example, the staggered arrangement of the water supply ports 6 is distorted. Even if the positional relationship between the water supply ports is an unequal triangle, the drainage port may be provided at the outer center thereof.

(B) FIGS. 4 to 5 are other examples in which the water supply ports 6 are arranged in a staggered manner in the partition wall 5.
FIG. 4 is a partial array diagram of the water supply / drainage port illustrating the positional relationship with the water discharge port 7 when focusing on the water supply port A. FIG. 5 is a plan view of the partition wall 5 in which the partial arrangement of the water supply / drain ports of FIG. 4 is developed on the partition wall.
The arrangement of the water supply ports 6 in FIG. 4 is the same as that in FIG. 2, but the arrangement of the drain ports 7 is different.

  That is, FIG. 4 is an example in which drainage ports q1 to q6 are provided at bisectors of each side of a triangle formed by three line segments connecting the adjacent water supply ports B to G with the water supply port A as a vertex. For example, the drainage port q1 is a point where the distances from the water supply ports A and B are equal, and the cooling water sprayed from the water supply ports A and B diffuses and merges along the surface of the hot steel plate 12. And since the discharge port q1 was provided at this confluence, drainage onto the partition wall was performed smoothly, and the cooling water steadily reached the surface of the hot steel plate 12 as shown in FIG. Since the cooling capacity and the drainage capacity are the same at all positions, a uniform temperature distribution can be obtained in the steel plate width direction.

  In FIG. 4, the triangle ABC is shown as an isosceles triangle having sides AB and AC that are equal in length. However, the present embodiment is not limited to this. For example, the staggered arrangement of the water supply ports 6 is distorted. Even if the positional relationship of the water supply port is an unequal triangle, the drainage port may be provided at the bisection point of each side.

(C) FIGS. 6-7 is the example which arranged the water supply port 6 in the partition 5 in the shape of a grid.
FIG. 6 is a partial array diagram of the water supply / drainage port illustrating the positional relationship with the water discharge port 7 when attention is paid to the water supply port A. FIG. FIG. 7 is a plan view of the partition wall 5 in which the partial arrangement of the water supply / drain ports of FIG. 6 is developed on the partition wall.

  As shown in FIG. 6, there are eight water supply ports B to J adjacent to the water supply ports A arranged in a grid pattern. One drainage port r1 to r4 is provided at the center of gravity of a quadrangle (rectangular shape) composed of four line segments connecting adjacent water supply ports 6 to each other.

  When the drain outlets are arranged in this manner, for example, the drain outlet r1 point has the same distance from the water inlets A, C, D, E, and the cooling water injected from the water inlets A, C, D, E is the hot steel plate 12. , And diffuse and merge along the surface of the hot steel sheet 12. And since the discharge port r1 is provided at this junction, the drainage onto the partition wall is smoothly performed, and the cooling water can reach the surface of the hot steel plate 12 steadily as shown in FIG. Since the cooling capacity and the drainage capacity are the same at all positions, a uniform temperature distribution can be obtained in the steel plate width direction.

  In FIG. 6, the quadrangular ACDE is shown as a rectangle, but the present embodiment is not limited to this, and for example, even if the grid-like arrangement of the grid of the water supply port 6 is distorted, the positional relationship of the water supply ports If it is square, a drain outlet may be provided at the center of gravity. Incidentally, since the nozzles are generally arranged at equal intervals in the width direction, the quadrangular ACDE can be regarded as at least a parallelogram, and the center of gravity is the intersection of two diagonal lines.

(D) FIGS. 8-9 is another example which arranged the water supply port 6 in the partition 5 in the shape of a grid.
FIG. 8 is a partial array diagram of the water supply / drainage port illustrating the positional relationship with the water discharge port 7 when the water supply port A is focused. FIG. 9 is a plan view of a partition wall in which the partial arrangement of the water supply / drainage port of FIG. 8 is developed on the partition wall.
The arrangement of the water supply ports 6 in FIG. 8 is the same as that in FIG. 6, but the arrangement of the drain ports 7 is different.

  In other words, FIG. 8 shows an example in which drainage ports s1 to s4 are provided at quadrilateral (rectangular) bisectors composed of four line segments connecting adjacent water supply ports 6 to each other. For example, the drain port s1 is a point where the distances from the water supply ports A and C are equal, and the cooling water sprayed from the water supply ports A and C diffuses and merges along the surface of the hot steel plate 12.

  And since the discharge port s1 is provided at this confluence, drainage onto the partition wall is performed smoothly, and the cooling water can reach the surface of the hot steel sheet 12 steadily as shown in FIG. Since the cooling capacity and the drainage capacity are the same at all positions, a uniform temperature distribution can be obtained in the steel plate width direction.

  In FIG. 8, the quadrangular ACDE is shown as a rectangle. However, the present embodiment is not limited to this. For example, even if the grid-like arrangement of the grid of the water supply port 6 is distorted, the positional relationship of the water supply ports Can be provided at the bisector of each side.

  By the way, whether the relative positional relationship of the water supply ports is regarded as a triangle as in the above (a) and (b) or as a quadrangle as in the above (c) and (d) depends on the arrangement method of the water supply ports. When the widest interior angle of a triangle formed by connecting adjacent water supply ports is 80 ° or more, it may be regarded as a quadrangle. For example, the triangle ACE in FIG. 6 is regarded as a square ACDE because the angle A is 90 °.

  If the total cross-sectional area of the drain port 7 is smaller than 1.5 times the total cross-sectional area of the inner diameter of the circular tube nozzle 3, the flow resistance of the drain port increases, and the stagnant water becomes difficult to drain. The amount of cooling water that can penetrate the steel plate and reach the steel sheet surface is greatly reduced, and the cooling ability is lowered, which is not preferable. More preferably, it is 4 times or more.

  By the way, the number of outlets per nozzle is 2 in FIG. 3 (a) and FIG. 9 in (d), 3 in FIG. 5 in (b), and 1 in FIG. 7 in (c). is there. For example, when the nozzle inner diameter is 5 mm and the discharge port is 10 mm in diameter, the total cross-sectional area of the drain port 7 is at least four times the total cross-sectional area of the inner diameter of the circular tube nozzle 3 in all of (a) to (d). It becomes. However, when the inner diameter of the nozzle is 8 mm and the outlet is 12 mm in diameter, the embodiment (a), (b) or (d) is preferred because (c) is only 2.25 times larger.

  On the other hand, if there are too many drain ports or the cross-sectional diameter of the drain ports becomes too large, the rigidity of the partition walls 5 will be reduced and it will be easily damaged when the steel plates collide. Therefore, the ratio of the total cross-sectional area of the drain outlet and the total cross-sectional area of the inner diameter of the circular tube nozzle 3 is preferably in the range of 1.5 to 20.

  The gap between the outer peripheral surface of the circular tube nozzle 3 inserted into the water supply port 6 of the partition wall 5 and the inner surface of the water supply port 6 is preferably 3 mm or less. If this gap is large, the cooling drainage discharged to the upper surface of the partition wall 5 is drawn into the gap between the outer peripheral surface of the circular pipe nozzle of the water supply port 6 due to the influence of the accompanying flow of the cooling water jetted from the circular pipe nozzle 3. Since it is supplied again onto the steel plate, the cooling efficiency is deteriorated. In order to prevent this, it is more preferable that the outer diameter of the circular tube nozzle 3 is substantially the same as the size of the water supply port 6, but in consideration of work accuracy and mounting error, a gap of up to 3 mm that is substantially less affected. Is acceptable. More preferably, it is 2 mm or less.

3 Cooling water injection nozzle and injection conditions Furthermore, in order to allow the cooling water to penetrate the staying water film and reach the steel plate, the inner diameter and length of the circular tube nozzle 3, the injection speed of the cooling water and the nozzle distance are also determined. Need to be optimized.

  That is, the inner diameter of the circular tube nozzle is preferably 3 to 8 mm. If it is smaller than 3 mm, the bundle of water sprayed from the nozzle becomes thin and the momentum becomes weak. On the other hand, if the nozzle diameter exceeds 8 mm, the flow rate becomes slow and the force penetrating the staying water film becomes weak.

  It is preferable that the cooling water sprayed from the nozzle is a rod-shaped cooling water having an injection speed of 8 m / s or more. This is because if it is less than 8 m / s, the force that the cooling water penetrates through the staying water film becomes extremely weak.

  Here, the rod-shaped cooling water in the present invention is cooling water injected in a state of being pressurized to some extent from a circular (including elliptical or polygonal) nozzle outlet, and is cooled from the nozzle outlet. The water jet velocity is 8 m / s or more, and the water flow jetted from the nozzle jet outlet is a continuous and straight water flow cooling water in which the cross section of the water flow is maintained in a substantially circular shape. That is, it is different from a free fall flow from a circular tube laminar nozzle or a liquid ejected in a droplet state such as a spray.

  The distance from the lower end of the cooling water jet nozzle 3 for cooling the upper surface to the surface of the steel plate 12 is preferably 30 to 120 mm. If it is less than 30 mm, the frequency with which the steel plate 12 collides with the partition wall 5 becomes extremely high, and equipment maintenance becomes difficult. This is because if the thickness exceeds 120 mm, the force through which the cooling water penetrates the staying water film becomes extremely weak.

The range of the water density that is most effective in the present invention is 1.5 m ³ / m ² · min or more. When the water density is lower than this, the staying water film does not become so thick, and even if the known technology of cooling the steel plate by free-falling the rod-shaped cooling water is applied, the temperature unevenness in the width direction does not become so large There is also. On the other hand, even when the water density is higher than 4.0 m ³ / m ² · min, it is effective to use the technique of the present invention, but there are problems in practical use such as an increase in equipment cost. The most practical water density is 1.5 to 4.0 m ³ / m ² · min.

4 About bottom surface cooling In this embodiment, it does not specifically limit about the cooling device by the side of a steel plate. In the embodiment shown in FIG. 1, a cooling header 2 having a circular tube nozzle 4 similar to the cooling device on the upper surface side is provided, and the partition wall 5 that discharges cooling drainage as in the upper surface side cooling in the steel plate width direction is not provided. Although an example is shown, the cooling equipment of the present invention provided with the same partition as the upper surface side may be applied. Moreover, you may use the well-known technique which supplies film-like cooling water, spray-like spray cooling water, etc.

As mentioned above, although the cooling equipment of this invention was demonstrated to the upper and lower surface cooling equipment of the steel plate shown in FIG. 1 as an example, this invention is not limited to this.
That is, in the present embodiment, the cooling facility after hot rolling of thick steel plates has been described, but the present invention can be applied as a cooling facility after hot rolling or heat treatment of steel materials such as thin plates and strips.

  Moreover, although the case of the rod-shaped cooling water using a circular pipe nozzle was described, the injection form is not limited to this, and various injection forms can be selected by selecting the injection nozzle. Furthermore, although the case where the cooling water is jetted vertically downward as the cooling equipment on the upper surface of the steel sheet has been described, the jetting direction is not limited to this, and the cooling water may be jetted vertically upward as the bottom cooling equipment. However, in addition to vertical, it is possible to use horizontal or oblique injection.

  Hereinafter, as an embodiment of the present invention, a case of cooling a steel plate having a tensile strength of 590 MPa class in a thick plate rolling process will be described with reference to the drawings.

  In the thick plate rolling facility schematically shown in FIG. 15, the slab extracted from the heating furnace is roughly rolled, then finish rolled to a steel plate having a plate thickness of 25 mm and a plate width of 4.5 m, and rolled at a steel plate surface temperature of 820 ° C. Ended. After rolling, accelerated cooling was performed through a hot leveler. The cooling conditions were a cooling start temperature of 780 ° C. and a cooling end temperature (a value obtained by measuring the temperature after recuperation on the exit side of the accelerated cooling facility) of 560 ° C.

  The cooling equipment used in the accelerated cooling test is the one provided with the cooling equipment of the present invention having the partition walls shown in FIG. 1 on the upper surface side of the steel sheet and the cooling equipment of the present invention having the same partition walls on the lower surface side of the steel sheet. It was.

  In this example, two types of examples of the present invention were tested for the arrangement of the water supply port 6 and the drain port 7 of the partition walls on the upper and lower surfaces of the steel plate. That is, Example 1 of the present invention has water supply ports arranged in a staggered manner as shown in FIG. 2, and a drain port is provided at the outer periphery of a triangle composed of three line segments connecting adjacent water supply ports. This is a case where six drain ports 7 are arranged at the apexes of a hexagon around one water port.

  In the present invention example 2, as shown in FIG. 6, the water supply ports 6 are arranged in a grid pattern, and a drainage port is provided at the center of gravity of a quadrangle composed of four line segments connecting adjacent water supply ports. This is a case where four drainage ports 7 are arranged at the apexes of a square around one water supply port. 2 and 6, a through hole having a diameter of 12 mm was formed in the partition wall, the tip of the circular tube nozzle 3 was inserted into the water supply port, and the remaining hole was used as a drain port.

  The dimensions of the used circular tube nozzles were an inner diameter of 5 mm, an outer diameter of 9 mm, a nozzle pitch in the steel plate width direction of 50 mm, and 10 rows of nozzles arranged in the longitudinal direction in a zone having a distance between table rolls of 1 m.

The cooling water injection speed and the water density are as follows. The top cooling water injection speed is 9.0 m / s in the present invention example 1, 12.0 m / s in the present invention example 2, and the lower cooling water injection speed is the present invention. Example 1 was 13.5 m / s, and Example 2 of the present invention was 18.0 m / s. Water flow rate of the upper surface cooling water, water density of the present invention Example 1 is 2.1m ³ / ^m 2 · min, the invention example 2 2.8m ³ / ^m 2 · min, the lower surface cooling water, the invention Example 1 Was 2.8 m ³ / m ² · min, and Inventive Example 2 was 4.2 m ³ / m ² · min.

  In both inventive examples 1 and 2, as shown in FIG. 14, the cooling water after cooling the steel sheet is quickly eliminated from the upper and lower surfaces of the steel sheet, so that the cooling water supplied subsequently penetrates the staying water film easily. We were able to.

  As a result, a high cooling capacity was ensured uniformly on the upper and lower surfaces. The temperature distribution in the width direction of the steel plate in this case was able to obtain a uniform temperature distribution in the width direction as shown in FIG. The cooling time for setting the cooling stop temperature at the center of the plate width to 560 ° C. was 2.5 seconds in Invention Example 1, and 2.1 seconds in Invention Example 2. Since the cooling rate became high, it became possible to reduce the steel alloy components (for example, Mn) necessary for obtaining high strength, and to reduce the manufacturing cost.

  The temperature distribution in the width direction of the steel plate was 550 to 560 ° C., and the distribution was almost uniform as shown in FIG. 12, and the temperature unevenness in the width direction of the steel plate (maximum temperature-minimum temperature) was small and became 10 ° C. For this reason, the pass rate of the material test was as high as 99.5%, and the yield was also sufficiently high.

  On the other hand, as Comparative Example 1, a conventional cooling facility in which a slit-shaped hole was provided in the partition wall described in Patent Document 2 and used as both a water supply port and a water discharge port was used. As shown in FIG. 13, in the cooling facility of Comparative Example 1, the cooling water after colliding with the steel plate is difficult to escape upward, so that the cooling stop temperature at the center of the plate width is set to 560 ° C. for 3 seconds. Water cooling time was required.

  The distribution of the cooling stop temperature in the plate width direction was concave as shown in FIG. 11, and the highest temperature in the vicinity of the end of the plate was 600 ° C. Therefore, the temperature unevenness (maximum temperature-minimum temperature) in the width direction was 40 ° C. As a result of taking out a part of the product and conducting a material test, the acceptance rate was as low as 70% and the yield was also poor.

  Furthermore, as Comparative Example 2, the amount of cooling water and the dimensions of the nozzle were the same as those of Example 1 of the present invention, and cooling was performed with the layout of the nozzle and the outlet as shown in FIG. That is, in Comparative Example 2, the discharge port 7 is provided in the middle position of the water supply port 6 arranged in the width direction, that is, the circular tube nozzle, and the nozzle row and the nozzle row as in Example 1 (FIG. 3) of the present invention. It is considered that it is most common to adopt the layout of the discharge port 7 provided in the partition wall 5 as in the present invention without providing a row of the discharge ports 7 between them.

  However, since there is no escape place for the cooling water sprayed from the two nozzles adjacent in the longitudinal direction, the drainage is poor and the cooling capacity is inferior as compared with Example 1 of the present invention. The cooling time for setting the cooling stop temperature at the center of the plate width to 560 ° C. was 2.8 seconds. Reduction of steel alloy components (for example, Mn) required for obtaining high strength was only about half that of Example 1 of the present invention.

  Hereinafter, as another embodiment of the present invention, a case of cooling a steel sheet having a tensile strength of 490 MPa class in a hot rolling process of an H-section steel will be described with reference to the drawings.

  In the H-section steel rolling facility schematically shown in FIG. 19, the steel piece extracted from the heating furnace is subjected to breakdown rolling and rough rolling, and then finish rolling to obtain a flange thickness of 36 mm, a flange width of 300 m, a web thickness of 16 mm, a web The height was 700 mm. The flange outer surface temperature during finish rolling was 800 ° C., and thereafter, the cooling start temperature of the flange outer surface was set to 780 ° C. and accelerated cooling was performed. The cooling end temperature (a value obtained by measuring the temperature after recuperation at the exit side of the accelerated cooling facility) was set to 580 ° C.

  As shown in FIG. 20, the cooling equipment used in the accelerated cooling test is the cooling equipment of the present invention that has the partition wall 5 between the outer surface of the flange 21 and the cooling header 23 and injects the jet cooling water 25 in the horizontal direction. is there. The cooling of the inner surface of the flange 21 and the upper and lower surfaces of the web 22 was not performed because of the problem of drainage.

  In this example, one type of arrangement of the water supply port 6 and the water discharge port 7 of the partition wall was tested as an invention example. That is, Example 3 of the present invention is such that the water supply ports 6 are arranged in a staggered manner as shown in FIG. 2, and the drainage ports 7 are provided at the outer periphery of a triangle formed by three line segments connecting the adjacent water supply ports 6 to each other. There is a case where six drain ports 7 are arranged at the apex of the hexagon around one water supply port 6. According to FIG. 2, a through hole having a diameter of 12 mm was formed in the partition wall 5, the circular tube nozzle 3 was inserted into the water supply port 6, and the remaining hole was used as the drain port 7.

The dimensions of the used circular tube nozzle were an inner diameter of 4 mm, an outer diameter of 8 mm, a flange pitch direction (vertical direction), and a nozzle pitch of 60 mm in the transport direction. The jetting speed of the cooling water was 8.2 m / s, and the water density was 2.7 m ³ / m ² · min.

  In the third example of the present invention, the cooling water 26 after cooling the outer surface of the flange 21 filled between the outer surface of the flange 21 and the partition wall 5 is quickly eliminated on the rear surface of the partition wall, as in the case of the upper surface cooling shown in FIG. Then, since it enters the space between the header 23 and the partition wall 5, the jet cooling water 25 supplied subsequently can penetrate the water film 27 filling the partition wall 5 and the outer surface of the flange 21.

  As a result, a high cooling capacity was ensured uniformly. The cooling time for setting the cooling stop temperature at the center of the flange 21 width to 580 ° C. is 2.4 seconds, and the temperature distribution in the flange 21 width direction is 570 to 580 ° C., as shown in FIG. As a result, an uneven temperature distribution in the flange width direction (maximum temperature-minimum temperature) was small and 10 ° C.

As a result, the pass rate of the material test was as high as 99.7%, and the yield was also sufficiently high.
Moreover, since a high cooling rate was obtained, it was possible to reduce the steel alloy components (for example, Mn) necessary for obtaining high strength, and the manufacturing cost could be reduced.

  On the other hand, as Comparative Example 3, cooling was performed with the same water density using a general spray cooling facility. In the cooling facility of Comparative Example 3, since the cooling water after colliding with the outer surface of the flange 21 falls in the vicinity of the outer surface of the flange 21, the cooling water supplied subsequently becomes the falling cooling water after colliding with the outer surface of the flange 21. It is obstructed and it becomes difficult to reach the outer surface of the flange 21.

  In particular, the cooling capacity decreased at a low position in the flange 21 height direction, and the flange 21 width direction distribution of the cooling stop temperature became higher as the lower part as shown in FIG. The lowest temperature near the top of the flange 21 is 560 °, the highest temperature near the bottom of the flange 21 is 600 ° C., and the temperature unevenness (maximum temperature-minimum temperature) in the flange width direction is 40 ° C. It became.

  As a result of taking out a part of the product and conducting a material test, the pass rate was as low as 80% and the yield was also poor.

It is a figure explaining arrangement | positioning of the cooling equipment of this invention. It is a partial arrangement figure of a water supply / drain port. It is a top view of the partition which developed FIG. It is another partial arrangement view of a water supply / drain port. It is a top view of the partition which developed FIG. It is a partial arrangement figure of a water supply / drain port. It is a top view of the partition which developed FIG. It is another partial arrangement view of a water supply / drain port. It is a top view of the partition which developed FIG. It is a figure explaining the flow of the cooling waste water on a partition. It is a figure explaining the steel plate width direction temperature distribution by a prior art example. It is a figure explaining the steel plate width direction temperature distribution by this invention. It is a figure explaining the flow of the cooling water by a prior art example. It is a figure explaining the flow of the cooling water by the example of the present invention. It is a figure explaining the outline of a thick plate rolling line. It is a figure explaining non-interference with the cooling drainage on the partition of the example of the present invention. It is a figure explaining interference with the cooling drainage on a partition when a nozzle tip is above a partition. It is a top view which shows an example of the partition of a comparative example. It is a figure explaining the outline of a H-section steel rolling line. It is a figure explaining application to the H section steel rolling line of the cooling equipment of the present invention. It is a figure explaining the steel plate width direction temperature distribution by this invention. It is a figure explaining the steel plate width direction temperature distribution by a prior art example.

Explanation of symbols

1 Upper header 2 Lower header 3 Upper cooling water injection nozzle (circular tube nozzle)
4 Lower cooling water injection nozzle (circular tube nozzle)
DESCRIPTION OF SYMBOLS 5 Partition 6 Water supply port 7 Drainage port 8 Injection cooling water 9 Drainage water 10 Draining roll 11 Table roll 12 Heated steel plate 21 Flange 22 Web 23 Header 24 Nozzle 25 Injection cooling water 26 Drainage water 27 Filled water film

Claims (5)

  A steel material cooling facility installed in a hot rolling line for steel materials, a header for supplying cooling water to the surface of the steel material, a cooling water jet nozzle extending from the header, and between the steel material and the header A partition wall to be installed, and a water supply port for interpolating a tip end portion of the cooling water injection nozzle, and a drain port for draining the cooling water supplied to the surface of the steel material to the back surface of the partition wall. Are provided in a large number, and the drain outlets are arranged at the outer circumference of a triangle composed of three line segments connecting the adjacent water inlets or at the bisection points of each side of the triangle. Steel cooling equipment.   A steel material cooling facility installed in a hot rolling line for steel materials, a header for supplying cooling water to the surface of the steel material, a cooling water jet nozzle extending from the header, and between the steel material and the header A partition wall to be installed, and a water supply port for interpolating a tip end portion of the cooling water injection nozzle, and a drain port for draining the cooling water supplied to the surface of the steel material to the back surface of the partition wall. And a plurality of the drain outlets are arranged at the center of gravity of a quadrilateral consisting of four line segments connecting the adjacent water inlets or at the bisection point of each side of the square. Steel material cooling equipment.   The steel material cooling facility according to claim 1 or 2, wherein the total cross-sectional area of the discharge port provided in the partition wall is 1.5 times or more the total cross-sectional area of the cooling water injection nozzle.   The steel material according to any one of claims 1 to 3, wherein a gap between an outer peripheral surface of a cooling water injection nozzle inserted in a water supply port provided in a partition wall and an inner surface of the water supply port is 3 mm or less. Cooling equipment. The cooling water injection nozzle has an inner diameter of 3 to 8 mm, and the cooling water injected from the cooling water injection nozzle is a rod-shaped cooling water having a flow velocity of 8 m / s or more, and the water amount density is 1.5 to 4.0 m ³ / m ^2. The steel cooling equipment according to any one of claims 1 to 4, wherein the cooling equipment is min.

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