KR100935357B1 - Cooling facility and production method of steel plate - Google Patents

Abstract

In order to manufacture high quality steel sheet cooling equipment and high quality steel sheet, which have good facility integrity, excellent drainage when supplying a large amount of cooling water to the lower surface of the steel sheet, and efficient cooling in the width direction to achieve high cooling rate. Provide a method. Specifically, the plurality of protective plates 34 arranged at equal intervals while obliquely moving in the conveying direction of the steel sheet 10 and the protective plate 34 and the protective plate 34 to supply cooling water to the lower surface of the steel sheet 10. In addition, the same number of raw-pipe nozzles 32 are arrange | positioned on the imaginary line 36 drawn in the plate | board width direction at a predetermined pitch in the nozzle row, and the nozzle row formed in the conveyance direction obliquely between them, The upper end of 32 is located at a lower position than the upper end of the protective plate 34.

Cooling Facility, Drainage, Facility Integrity

Description

Cooling Facility and Manufacturing Method of Steel Plate {COOLING FACILITY AND PRODUCTION METHOD OF STEEL PLATE}

TECHNICAL FIELD This invention relates to the cooling installation of a steel plate, and a manufacturing method.

In the process of manufacturing a steel sheet by hot rolling, it is common to supply cooling water or to perform air cooling to control the rolling temperature. However, in recent years, a high cooling rate has been achieved to refine the structure, thereby reducing the strength of the steel sheet. The development of technology to raise the number is active.

For example, there exists a technique of Unexamined-Japanese-Patent No. 62-259610 as a technique of supplying cooling water and cooling a hot steel plate. As shown in Fig. 7, a header 51 serving as an apron is provided between the table rollers 14, and a plurality of holes, so-called porous nozzles 52, are provided on the upper surface of the header 51. It is a technique of forming and supplying the rod-shaped cooling water 53 to the lower surface of the steel plate 10 here. It is said that a high cooling rate is obtained by supplying a relatively large amount of cooling water to the steel sheet.

Moreover, as another technique of cooling a steel plate by supplying cooling water, there exists a technique of Unexamined-Japanese-Patent No. 10-263669. This makes it possible to arrange the nozzle in a honeycomb shape and to perform efficient cooling.

However, the techniques described in Japanese Patent Application Laid-Open No. 62-259610 and Japanese Patent Application Laid-open No. Hei 10-263669 have advantages in terms of facility integrity, drainage after supplying cooling water to the lower surface of the steel sheet, and even cooling uniformity. There is a big problem.

In the technique described in Japanese Patent Laid-Open No. 62-259610, as shown in Fig. 7, the header 51 of the lower surface cooling installation 50 has a structure serving as an apron between the table rollers 14, so that the tip is In the case where the steel sheet 10 is pushed downward, the steel sheet 10 hits the header 51, and there is a problem that the header 51 is broken. If the header 51 is damaged and the hole of the nozzle 52 is clogged or deformed, the uniformity of cooling is remarkably impaired. Therefore, if the technique is used for a long time, the header (apron) 51 is used. It must be replaced frequently, and there is a problem in equipment integrity.

In addition, when the cooling water 53 falls after being supplied to the steel plate 10, it forms on the header (apron) 51, and the water film 54 is formed. Since the hole drilled in the upper surface of the header 51, which becomes the apron, becomes the nozzle 52, the newly supplied cooling water must be supplied to the lower surface of the steel sheet 10 through this water film 54, but to increase the amount of cooling water. In this case, the thicker the water film 54 is, the worse the cooling efficiency becomes.

In addition, since the cooling water is drained only through a narrow gap between the end portion of the header (apron) 51 and the table roller 14, this drainage inhibits cooling by the newly supplied cooling water, thereby making the cooling water more efficient. Can't use it well.

On the other hand, the technique described in Japanese Patent Application Laid-open No. Hei 10-263669 is also used when cooling the lower surface of the steel sheet in the hot rolling line, when the tip is downward, it hits the nozzle, There is a problem of breakage. It is also conceivable to prevent the tip of the steel sheet from colliding with the nozzle by providing a protective plate between the nozzles. However, the nozzles are arranged at a pitch of 1/2 pitch in the conveying direction and the width direction of the steel sheet, so that the nozzles Because the gap is too narrow, it is not possible to install a suitable shield. Therefore, the cooling material can only be used in a process in which there is no fear that the coolant will collide with the nozzle, and it cannot be used for cooling the steel sheet in the hot rolling line.

This invention is made | formed in view of the above circumstances, and it is excellent in equipment integrity, excellent drainage property when supplying a large amount of cooling water to the lower surface of steel plate, and it performs high efficiency uniformly in the width direction, and performs high It is an object of the present invention to provide a cooling facility for steel sheets and a method for producing high quality steel sheets for realizing a cooling rate.

(Initiation of invention)

(Tasks to be solved by the invention)

In order to solve the said subject, this invention has the following characteristics.

[1] A cooling apparatus for a steel sheet provided in a hot rolling line of a steel sheet, wherein the plurality of protective plates are disposed obliquely in a conveying direction of the steel sheet under the steel sheet to be conveyed, and a protective plate for supplying cooling water to the lower surface of the steel sheet. And a nozzle row provided at an angle between the protective plate and the conveying plate at an angle to the conveying direction of the steel sheet, wherein the nozzle rows each have the same number of pipes on an imaginary line drawn at a constant pitch in the sheet width direction of the steel sheet. ) And the upper end of the tubular nozzle is located at a position lower than the upper end of the protective plate, characterized in that the nozzle is arranged.

[2] The steel sheet cooling equipment according to the above [1], wherein the header with the tubular nozzle is located at a position lower than an axis of the table roller for conveying the steel sheet.

[3] The upper end of the tubular nozzle is located at a position higher than the axis of the table roller for conveying the steel sheet, wherein the steel sheet cooling equipment according to the above [1] or [2].

[4] The tubular nozzle is a round tube nozzle, the inner diameter of the nozzle is 3 to 8 mm, and the spraying speed is 1 to 10 m / s, in any one of the above [1] to [3]. Cooling equipment of the steel sheet described.

[5] A method for manufacturing a steel sheet for cooling the steel sheet in a hot rolling line of the steel sheet, wherein a plurality of protective plates are disposed while obliquely moving in the conveying direction of the steel sheet below the conveyed steel sheet, and cooling water is provided on the lower surface of the steel sheet. In order to supply, nozzle rows are formed between the protection plate and the protection plate at an oblique direction in the conveying direction of the steel plate, and the same number of tubular nozzles are arranged on the imaginary line drawn at a constant pitch in the plate width direction of the steel plate. In addition, the method of manufacturing a steel sheet characterized in that the upper end of the tubular nozzle is located at a position lower than the upper end of the protective plate.

[6] The method for producing a steel sheet according to the above [5], wherein the header with the tubular nozzle is positioned at a position lower than an axis of the table roller for conveying the steel sheet.

[7] The method for producing a steel sheet according to the above [5] or [6], wherein an upper end of the tubular nozzle is positioned at a position higher than an axis of the table roller for conveying the steel sheet.

[8] The tubular nozzle is a round tube nozzle, the inner diameter of the nozzle is 3 to 8 mm, and the injection speed is 1 to 10 m / s. The production of the steel sheet according to any one of the above [5] to [7]. Way.

In the present invention, since the tubular nozzle for supplying cooling water to the lower surface of the steel sheet is protected by a protective plate, even when the steel sheet with the tip protruded downward enters, damage to the tubular nozzle is prevented and equipment integrity is maintained. In addition, since the tubular nozzles are arranged in a predetermined arrangement, even when a large amount of cooling water is supplied to the lower surface of the steel sheet, the cooling water is smoothly drained between the gaps between the tubular nozzles, and the drainage is excellent. As a result, efficient cooling can be performed uniformly in the width direction to realize a high cooling rate, and a high quality steel sheet can be manufactured.

In addition, the cooling water supplied from the tubular nozzle prescribed | regulated by this invention is rod-shaped cooling water. Here, the rod-shaped cooling water (also called columnar cooling water) refers to the cooling water injected from the nozzle jet port of a circular shape (including ellipse or polygonal shape). In addition, the rod-shaped cooling water refers to a continuous and straight stream of cooling water in which the cross section of the stream of water is maintained in a substantially circular shape until it hits the steel sheet from the nozzle jet port, rather than in the form of a spray shape.

1 is a schematic diagram of a hot rolling line of a thin steel sheet.

2 is an explanatory diagram of a cooling system according to an embodiment of the present invention.

Fig. 3 is a diagram showing a nozzle arrangement column of the header in one embodiment of the present invention.

4 is a view showing another nozzle arrangement row.

5 is a view showing another nozzle arrangement row.

6 is a view showing another nozzle arrangement row.

7 is an explanatory diagram of a prior art.

(Explanation of the sign)

10 steel sheet

11: heating furnace

12: hot rolling mill

13: run out table

14: table roller

14a: shaft center of table roller

20: upper surface cooling equipment

30: lower surface cooling equipment

31: header

32: nozzle

33: coolant

34: shield

35: shield

36: virtual line

50: lower surface cooling equipment

51: header

52: spout (nozzle)

53: coolant

54: water film

(The best form to carry out invention)

Embodiment of this invention is described below. In addition, the case where the present invention is used for cooling the steel sheet in a run out table in the hot-rolled hot rolled line of the thin steel sheet is described as an example.

1 is a diagram showing an outline of a hot rolled hot rolled line of a thin steel sheet in which the present invention is used. Reference numeral 11 denotes a heating furnace, reference numeral 12 denotes a hot rolling mill consisting of a rough rolling mill and a finish rolling mill, and reference numeral 13 denotes a run out table, and above the run out table 13, The upper surface cooling facility 20 for supplying cooling water to the upper surface of the steel plate 10 is provided at predetermined intervals in the conveyance direction (henceforth simply a conveyance direction) of the steel plate 10, and of the runout table 13 Below, the lower surface cooling installation 30 for supplying cooling water to the lower surface of the steel plate 10 from between the gaps of the table rollers 14 is provided in a conveyance direction at predetermined intervals.

In this hot rolling hot rolling line, after the slab extracted from the heating furnace 11 is rough-rolled and finish-rolled by the hot rolling heat | fever 12, it becomes a predetermined | prescribed finishing plate thickness at predetermined finishing temperature, It is conveyed to the runout table 13, and is cooled to predetermined temperature by the cooling water sprayed from the upper surface cooling installation 20 and the lower surface cooling installation 30.

2 is a view showing the lower surface cooling installation 30 in one embodiment of the present invention, and FIG. 3 is a plan view showing the nozzle arrangement of the lower surface cooling installation 30.

As shown in FIG. 2, FIG. 3, the lower surface cooling installation 30 adjoins the header 31, the some protection plate 34 arrange | positioned at the upper surface of the header 31, and obliquely progresses to a conveyance direction, and the adjacent protection plate ( (34) An imaginary line (broken line in Fig. 3) provided with nozzle rows (here, two rows) provided in the header 31 while obliquely moving in the conveying direction between the nozzle rows, and drawn at a constant pitch in the plate width direction. The same number of nozzles (each each here) 32 is arrange | positioned on the phase. And the upper end (tip) of the cylindrical pipe nozzle 32 which injects a rod-shaped cooling water is a position lower than the upper end of the protection plate 34, and is located in the position higher than the shaft center 14a of the table roller 14. As shown in FIG. In addition, the header 31 with the cylindrical pipe nozzle 32 is located at a position lower than the shaft center 14a of the table roller 14. In addition, the inner diameter of the round tube nozzle 32 is 3-8 mm, and the injection speed is 1-10 m / s. In addition, it is preferable that the space | interval of the protection plate 34 is equal interval.

In the lower surface cooling installation 30 comprised as mentioned above, since the tube nozzle 32 which supplies the rod-shaped cooling water 33 to the lower surface of the steel plate 10 is protected by the protection plate 34, the front-end | tip is bent downwards. Even when the steel sheet enters, damage to the original tube nozzle 32 is prevented and facility integrity is good. Therefore, since cooling can be performed for a long period of time with the original tube nozzle 32 in a favorable state, generation | occurrence | production of the temperature nonuniformity of a steel plate can be prevented, without performing facility maintenance or the like.

In addition, since the original tube nozzle 32 is arrange | positioned in a predetermined | prescribed arrangement, even if a large amount of cooling water 33 is supplied to the lower surface of the steel plate 10, the cooling water will smoothly drain between the gaps between the original tube nozzles 32. It is excellent in drainage property. In addition, since the header 31 is located at a position lower than the shaft center 14a of the table roller 14, the flow of the cooling water is not impeded between the header 31 and the table roller 14, so that the cooling water It drains more smoothly. As a result, since the coolant does not stay on the upper surface of the header 31 and the jet port at the tip of the tube nozzle 32 does not sink, the coolant is always supplied to the lower surface of the steel plate 10 so that the efficiency is high. Cooling can be performed.

In the above description, the tip of the cylindrical tube nozzle 32 is positioned at a position higher than the shaft center 14a of the table roller 14. The tip of the cylindrical tube nozzle 32 is too far from the lower surface of the steel plate 10. If it falls, the influence of falling cooling water also exists, and high injection pressure is required in order to supply the cooling water predominantly to the lower surface of the steel plate 10.

In addition, the inner diameter of the cylindrical nozzle 32 is set to 3 to 8 mm. If the inner diameter is smaller than 3 mm, nozzle clogging may occur frequently, and jet flow may be thin. This is because the lower surface of the steel sheet 10 may not be reached, and the cooling capacity is lowered. When the inner diameter is larger than 8 mm, it is necessary to widen the interval of the nozzles and to suppress the injection speed to some extent. This is because the temperature nonuniformity increases and the cooling capacity also decreases.

In addition, the injection speed from the original tube nozzle 32 is set to 1 to 10 m / s because, when the injection speed is less than 1 m / s, the impingement of the cooling water on the steel plate 10 is weak, and sufficient cooling is not performed. This is because, when the injection speed exceeds 10 m / s, an abnormally high fountain ejection height becomes high, and scattering of the cooling water around the facility becomes a problem.

Moreover, the well-known cooling apparatus provided with the round tube nozzle etc. is used for the upper surface cooling apparatus 20. As shown in FIG.

Thus, by cooling the steel plate 10 on the runout table 13 using the lower surface cooling installation 30 as mentioned above, it is excellent in facility integrity and drainage property, and efficient cooling is carried out to the width direction. By performing uniformly, high cooling rate can be realized and high quality steel sheet can be manufactured.

In addition, in this embodiment, although the original tube nozzle 32 is used as the nozzle of the lower surface cooling installation 30, you may use other tubular nozzles, such as a square tube nozzle.

In addition, arrangement | positioning of the protection plate 34 and the cylindrical tube nozzle 32 is not limited to what was shown in FIG. 3, As shown in FIG. 4, three rows of nozzles are arrange | positioned between adjacent protection plates 34, One cylindrical pipe nozzle 32 may be arranged on the virtual line 36, respectively. In addition, as shown in FIG. 5, FIG. 6, the nozzle row may be divided into two in the conveyance direction, and the arrangement | positioning may pass the protection plate 35 of the plate width direction between them.

Moreover, it can not only use for the hot rolling line of a thin steel plate, but can also use for the hot rolling line of a thick steel plate.

(Example)

As an embodiment of the present invention, the steel sheet in the run-out table 13 was cooled in the hot rolling line of the thin steel sheet outlined in FIG. 1. At that time, finishing temperature was 880 degreeC and the finishing plate | board thickness was 4 mm, and the run out table 13 cooled to 550 degreeC.

As an example of this invention, the rod-shaped cooling water was supplied to the lower surface of the steel plate using the lower surface cooling installation 30 shown in said embodiment. Here, the steel plate of thickness 22mm was used for the protection plate 34, and the inner diameter of the round tube nozzle 32 was 6 mm.

On the other hand, as a comparative example, as shown in FIG. 7, the cooling apparatus 50 of the said Unexamined-Japanese-Patent No. 62-259610 which provided the header 51 which doubled the apron between the table rollers 14 was used. Rod-shaped cooling water was supplied to the lower surface of the steel plate 10.

In the present invention and the comparative examples, the flow rate density of the cooling water supplied to the lower surface of the steel sheet was 2 m 3 / m 2 min, and the distance between the nozzle jet port and the lower surface of the steel sheet 10 was 150 mm. Moreover, also about the upper surface of the steel plate 10, the rod-shaped cooling water of flow volume density 1m <3> / m <2> min was supplied using the well-known technique.

Table 1 shows the results of comparing the equipment integrity, the drainage of the cooling water and the cooling capacity with respect to the examples of the present invention and the comparative examples. In Table 1, the case where the fall of productivity and quality appeared was x, and the case where it was not was set as (circle).

  Nozzle  Equipment damage  Immersion of Cooling Water Jet   Cooling rate  Longitudinal temperature unevenness  Width direction temperature nonuniformity  Material strength deviation  Comparative example  Perforated Plate  × Yes  × Yes  20 ℃ / s  × 30 ℃  × 30 ℃  × large  Inventive Example  Tube  ○ none  ○ none  30 ℃ / s  ○ 10 ℃  ○ 10 ℃  ○ small

As shown in Table 1, in the comparative example, when the steel plate whose tip was lowered in entered, it collided with the header upper surface which also serves as an apron, and the equipment might be damaged. As a result, the upper surface of the header 51 dents, the jet port 52 deforms, and the spraying direction of the cooling water 53 becomes uneven, and the temperature nonuniformity in the plate width direction may be 30 ° C. In addition, the cost of repairing the damage point of the facility is high, and the productivity is often lowered by stopping the operation.

In addition, since the cooling water after being supplied to the lower surface of the steel plate 10 is drained only from between the narrow gap between the header 51 and the table roller 14, the water film 54 is stuck on the header (apron) 51. The cooling water 53 which is formed and sprayed from the jet port 52 reaches the lower surface of the steel sheet 10 after the momentum is deteriorated by the water film 54, so that efficient cooling is not performed, but it is combined with the cooling of the upper surface. The cooling rate at the time of hitting was low at 20 degree-C / s.

This water film 54 was not formed at the time when the tip portion of the steel sheet 10 passed, and was formed after a while after the tip portion passed. Therefore, only the front end of the steel plate 10 cooled well, and the temperature difference with the top part cooled after the water film 54 was formed was 30 degreeC.

Thus, since temperature nonuniformity became large, it became the steel plate (difference between maximum strength and minimum strength: 3 kgf / mm <2> or more) with large variation in material strength, such as tensile strength.

On the other hand, in the example of this invention, even when the steel plate which the front end entered below hits the protection plate 34 only, and since the steel plate 10 did not enter further downward, such as the original tube nozzle 32 etc. The equipment was not damaged. Thereby, since cooling could be performed with the original tube nozzle 32 in the favorable state, generation | occurrence | production of the temperature nonuniformity of the plate width direction was able to be suppressed within 10 degreeC, without performing facility maintenance etc .. FIG. Moreover, since the operation was not stopped, high productivity was maintained.

In addition, since the column nozzles 32 are arrange | positioned in a predetermined | prescribed arrangement, since the header 31 is located in the position lower than the shaft center 14a of the table roller 14, cooling water of the tube nozzles 32 In addition to the smooth drainage between the gaps, the flow was not impeded between the header 31 and the table roller 14. Accordingly, since the coolant does not stay on the upper surface of the header 31 and the jet port at the tip of the tube nozzle 32 does not sink, the rod-shaped coolant 33 which is always momentarily supplied to the lower surface of the steel plate 10 is supplied. It was possible to perform efficient cooling, and the cooling rate when combined with the cooling of the upper surface was improved to 30 ° C / s. Moreover, since the cooling water was always supplied in the same state from the front end pass to the end pass of the steel sheet, the temperature nonuniformity in the longitudinal direction was reduced to 10 ° C.

Thus, since temperature nonuniformity can be suppressed extremely small in the longitudinal direction and the width direction of a steel plate, the variation of material strength, such as tensile strength, can be made small (difference between maximum strength and minimum strength: 1 kgf / mm <2> or less), High quality steel sheet could be produced.

Claims (10)

A cooling apparatus for a steel sheet provided in a hot rolling line of a steel sheet, wherein a plurality of protective plates arranged while obliquely moving in the conveying direction of the steel sheet under the steel sheet being conveyed, and a protective plate and a protective plate for supplying cooling water to the lower surface of the steel sheet. It is provided with the nozzle row formed obliquely to the conveyance direction of a steel plate between them, Comprising: The same number of tubular nozzles are respectively arrange | positioned on the imaginary line drawn by the fixed pitch in the plate width direction of the steel plate in the said nozzle row, And the upper end of the tubular nozzle is located at a lower position than the upper end of the protective plate. The method of claim 1, The header with a tubular nozzle is a cooling apparatus of the steel plate located in the position lower than the shaft center of the table roller which conveys a steel plate. The method according to claim 1 or 2, The upper end of the said tubular nozzle is cooling equipment of the steel plate located in the position higher than the axis center of the table roller which conveys a steel plate. The method according to claim 1 or 2, The tubular nozzle is a round tube nozzle, the nozzle has an inner diameter of 3 to 8 mm, and a spraying speed of 1 to 10 m / s. As a method for manufacturing a steel sheet for producing a steel sheet in a hot rolling line of the steel sheet, in order to supply cooling water to the lower surface of the steel sheet while arranging a plurality of protective plates at an angle downward in the conveying direction of the steel sheet under the conveyed steel sheet. Nozzle rows are formed between the protective plate and the protective plate at an angle in the conveying direction of the steel sheet, and the same number of tubular nozzles are respectively arranged on the imaginary line drawn at a constant pitch in the plate width direction of the steel sheet. A method for producing a steel sheet, wherein the upper end of the tubular nozzle is positioned at a position lower than the upper end of the protective plate. The method of claim 5, A method for producing a steel sheet, wherein the header with the tubular nozzle is positioned at a position lower than an axis of the table roller for conveying the steel sheet. The method according to claim 5 or 6, The manufacturing method of the steel plate which positions the upper end of the said tubular nozzle to a position higher than the shaft center of the table roller which conveys a steel plate. The method according to claim 5 or 6, The said tubular nozzle is a round tube nozzle, the inside diameter of a nozzle is 3-8 mm, and the injection speed is a manufacturing method of the steel plate of 1-10 m / s. The method of claim 3, The tubular nozzle is a round tube nozzle, the nozzle has an inner diameter of 3 to 8 mm, and a spraying speed of 1 to 10 m / s. The method of claim 7, wherein The said tubular nozzle is a round tube nozzle, the inside diameter of a nozzle is 3-8 mm, and the injection speed is a manufacturing method of the steel plate of 1-10 m / s.

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