JP6439943B2 - Steel plate bottom surface cooling method and cooling device - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a steel plate lower surface cooling method and cooling device, and more specifically, to a lower surface of a hot steel plate (hot rolled steel strip, thick steel plate, etc.) formed by hot rolling a slab, The present invention relates to a method and an apparatus for cooling the lower surface by injecting cooling water from a plurality of nozzles arranged in a direction orthogonal to the conveying (passing plate) direction of the steel plate.

  In a production line for hot steel plates, for example, hot-rolled steel plates, as shown in FIG. 11, the slab heated to a high temperature in a heating furnace is descaled for primary scale removal, and then comprises a rough rolling mill and a finish rolling mill. The hot-rolled steel sheet is rolled into a hot-rolled steel sheet by means of a hot rolling mill, and thereafter, the hot-rolled steel sheet is controlled and cooled by a water-cooled or air-cooled cooling facility during conveyance on a run-out table. Cooling during conveyance on the run-out table is performed in order to obtain a desired material such as strength and elongation by controlling precipitates and transformation structure of the steel sheet. However, when the temperature distribution in the width direction of the steel sheet after cooling becomes uneven, there is a problem that mechanical properties such as strength and elongation change in the width direction of the steel sheet, and a predetermined material cannot be obtained locally.

In hot-rolled steel sheet cooling, laminar flow cooling is often used for the upper surface, and spray cooling is often used for the lower surface. It is said that will occur.
That is, when cooling the upper surface of the steel sheet by laminar flow, a plurality of nozzles are attached to the header arranged at right angles to the traveling direction of the steel sheet, and cooling water is sprayed from each nozzle all at once. Since the cooling water which reached | attains forms the water flow which goes to the width direction of a steel plate, passing water amount increases so that it goes to the edge part (width direction edge part) of a steel plate, and it cools more. Therefore, the cooling capacity for the vicinity of the edge portion of the steel plate is higher than that for the central portion, and the temperature distribution is often lower at both edge portions of the steel plate than at the central portion.

On the other hand, a non-uniform temperature distribution may occur in the width direction of the steel sheet due to cooling by spraying the lower surface.
That is, in many run-out tables, the table rolls are densely arranged for the passage stability, and the space between the table rolls is narrow. Therefore, when the steel plate lower surface is cooled, a plurality of spray nozzles that can be installed in a narrow space and can secure a wide cooling area are often arranged in the steel plate width direction. Furthermore, in order to ensure a high cooling capacity, there are cases in which the nozzle pitch in the steel plate width direction is made dense. In the cooling of the lower surface of the steel plate using this spray nozzle, as shown in FIG. 12, the cooling is sprayed from a position where the steel plate does not pass above, that is, from the spray nozzle arranged outside the width direction end of the steel plate. The water drops after several hundred mm to several m from the pass line, but a part of the cooling water falls on the upper surface of the steel plate. Further, the cooling water may directly collide with the end face in the width direction of the steel plate. Direct impingement of the falling water and the cooling water on the end surface in the width direction of the steel sheet causes overcooling of the end portion in the width direction of the steel sheet. Such problems occur not only in run-out cooling of hot-rolled steel sheets, but also in controlled cooling of thick steel sheets and cooling devices during rolling of thick steel sheets and hot-rolled steel sheets, and have similar problems.

  In order to prevent such overcooling of the end in the width direction of the steel plate, Patent Document 1 describes that the spray nozzle corresponds to the spray nozzle group composed of a plurality of spray nozzles arranged on the lower surface side of the steel plate. Provided with a perforated shielding plate having a plurality of holes and a drive mechanism for moving the perforated shielding plate in the steel plate width direction, and moving the perforated shielding plate in the steel plate width direction, thereby providing an end side in the steel plate width direction. A technique for blocking part or all of the cooling water from the nozzle of the steel sheet is disclosed. According to this technique, the cooling water wraps around the upper surface of the steel sheet and the cooling water directly collides with the end face in the width direction of the steel sheet. Thus, overcooling of the end portion in the width direction of the steel plate can be prevented.

  In addition, in Patent Document 2, for the nozzle on the upper surface side of the steel plate, a hook for adjusting the amount of cooling water falling at the end in the width direction of the steel plate to be less than the central portion in the width direction of the steel plate is provided below the nozzle, A method for preventing overcooling of the end in the width direction of the steel sheet is disclosed. A plurality of such methods are disclosed in addition to Patent Document 2, and for example, a method of providing a shielding plate so that the cooling water does not fall at the widthwise end of the steel plate is also proposed as its application. In addition, there is an example in which such a technique is applied not only to the upper surface of the steel sheet but also to the lower surface.

JP 2012-91194 A JP 2005-238283 A

  An example of arrangement | positioning of the spray nozzle in the lower surface cooling apparatus of a hot-rolled steel plate is shown to FIGS. Here, FIG. 12 is a front view of the lower surface cooling device as viewed in the conveying direction, FIG. 13 is a plan view of a plurality of spray nozzles arranged between the table rolls of the runout table, and FIG. 14 is arranged between the table rolls. It is a side view which shows the made spray nozzle with a lower surface cooling header.

  As shown in FIGS. 12 to 14, a general steel plate lower surface cooling device includes a plurality of spray nozzles arranged at a predetermined nozzle pitch along the steel plate width direction between table rolls. This is a flat type in which cooling water is jetted flat and fan-shaped from the nozzle tip. In order to obtain a high cooling capacity, the spray nozzle is often arranged densely with the nozzle pitch in the steel plate width direction being about 50 to 200 mm. In addition, the spray nozzle is inclined with respect to the transport direction in plan view so that the cooling water spreads over the entire width direction of the steel plate. As shown in FIGS. 13 and 14, the ejection plane is a plane including the front and rear edges of the fan-shaped ejection range.

  When cooling water is sprayed from such a spray nozzle, as shown in FIG. 12, the cooling water sprayed from the outside in the width direction of the steel sheet spreads and is sprayed, so that the cooling water falls on the upper surface of the steel sheet, Cooling water directly collides with the end surface in the width direction of the steel plate, causing overcooling of the end portion in the width direction of the steel plate.

  The method disclosed in Patent Document 1 is a diagram in which the relationship between the jet cooling water and the shielding plate at each stage viewed from above is shown in FIG. 15, and the relationship between the jet cooling water and the shield plate at each stage is corrected in the transport direction. As shown in FIG. 16, the perforated shielding plate having a plurality of holes is moved in the steel plate width direction so that a part of the cooling water from the nozzle outside the width direction end of the steel plate is obtained. Alternatively, all of them are blocked to prevent overcooling of the end in the width direction of the steel plate. Specifically, when the plate width is large, as shown in FIGS. 15 (a) and 16 (a), When the shielding plate is disposed at a position where the cooling water sprayed from all the spray nozzles passes through the rectangular hole, and the plate width is smaller than the width direction range in which the spray nozzles are disposed, FIG. And as shown in FIG.16 (b), let the shielding board be a nozzle of the outer side of the width direction edge part of a steel plate. Is moved to a position where half is shielded, thereby it is to prevent direct impingement of the cooling water in the widthwise end face of the falling water and the steel plate to the steel plate top surface. However, with a shielding plate having a short hole as shown in FIGS. 15 and 16, it is difficult to control the shielding of each nozzle, and depending on the plate width, not only the outer side of the width direction end of the steel plate but also the inner nozzle is half. In some cases, the cooling water sprayed to the end in the width direction of the steel sheet is halved, and there is a concern about insufficient cooling or uneven cooling at the end in the width direction of the steel sheet. Moreover, as shown in FIG. 15, when the length along the steel plate width direction of the jet cooling water when passing through the rectangular hole is L, the minimum stroke required to shift the shielding pattern by one level is L / 2. For example, when L = 45 mm and the nozzle pitch P in the width direction is 80 mm, there is only one type of shielding pattern as shown in FIG.

  The method disclosed in Patent Document 2 is to prevent the overcooling of the width direction end portion by adjusting the amount of cooling water at the width direction end portion of the steel plate by using a gutter or a shielding plate. Nozzle arrangement in the case where the distance between the table rolls is wide is described. As a driving mechanism for the shielding plate, a wire or a screw is used, but a general hot-rolled steel sheet has a minimum width of about 600 mm and a maximum width of about 2400 mm, and the width direction driving distance of the shielding plate is as long as 900 mm on one side. It is necessary to drive. Furthermore, especially in the case of a line having a plate width exceeding 5000 mm, such as a thick steel plate, the difference between the minimum plate width (1500 to 2000 mm) and the maximum plate width (4000 to 5500 mm) is large, and the width direction driving distance of the shielding plate is also on one side. Since a long distance of 1000 to 2000 mm is driven, the scale becomes larger than that of a hot-rolled steel sheet. Moreover, since the cooling water sprayed from the nozzle falls on the lower surface of the steel plate after colliding with the steel plate, the drive mechanism such as a screw or wire gets wet, and there are very many failures due to rust and the like. For this reason, the masking device using the shielding plate on the lower surface has not been operated stably in practice.

  An object of the present invention is to solve the above-mentioned problems, to realize a technique capable of preventing overcooling of the end portion in the width direction of the steel sheet and ensuring a high-quality steel sheet with little material variation.

In order to solve the above problems, the lower surface cooling method of the steel sheet of the present invention is a lower surface cooling method of the steel sheet for cooling the lower surface of the steel sheet being conveyed,
A plurality of nozzles that are aligned in the width direction of the steel sheet, each of which sprays cooling water in a fan shape, and the spray plane including the front and rear edges of the fan-shaped spray range is inclined with respect to the transport direction;
A shielding plate having a plurality of openings that are provided so as to be movable in the width direction of the steel plate between the nozzle and the steel plate, and allow or pass the cooling water sprayed from the nozzle according to the amount of movement. A shielding plate that shields cooling water according to the amount of movement of the shielding plate among the opening edges that define the opening, and is inclined to the same side as the inclined side of the ejection plane with respect to the transport direction; Use
A part or all of the cooling water from the nozzle on the end side in the steel plate width direction is shielded by moving the shielding plate close to and away from the center in the steel plate width direction according to the steel plate width.

  In the lower surface cooling method of the steel sheet of the present invention, when the inclination angle of the shielding edge with respect to the conveyance direction is φ [rad] and the inclination angle of the injection plane with respect to the conveyance direction is θ [rad], the shielding edge The inclination angle φ of the part is preferably set so as to satisfy 0 <φ <arctan (2 tan θ).

  Moreover, in the lower surface cooling method of the steel plate of this invention, it is preferable to provide 2 or more types of the width direction dimensions of the said opening part.

In order to solve the above problems, the lower surface cooling device for a steel plate of the present invention is a lower surface cooling device for a steel plate that cools the lower surface of the steel plate being conveyed,
A plurality of nozzles that are aligned in the width direction of the steel sheet, each of which sprays cooling water in a fan shape, and the spray plane including the front and rear edges of the fan-shaped spray range is inclined with respect to the transport direction;
A shielding plate having a plurality of openings that are provided so as to be movable in the steel plate width direction between the nozzle and the steel plate, and allow or pass cooling water sprayed from the nozzle according to the amount of movement;
A drive mechanism for moving the shielding plate in the width direction of the steel plate,
Among the opening edges that define the opening, the shielding edge that shields the cooling water according to the movement amount of the shielding plate is inclined to the same side as the inclined side of the injection plane with respect to the transport direction. It is what.

  In the lower surface cooling apparatus for a steel sheet of the present invention, when the inclination angle of the shielding edge with respect to the conveying direction is φ [rad] and the inclination angle of the ejection plane with respect to the conveying direction is θ [rad], the shielding is performed. The inclination angle φ of the edge is preferably set so as to satisfy 0 <φ <arctan (2 tan θ).

  Moreover, in the lower surface cooling apparatus of the steel plate of this invention, it is preferable that the width direction dimension of the said opening part is provided 2 or more types.

  Furthermore, in the steel plate lower surface cooling device of the present invention, it is preferable that the drive mechanism has a drive stroke less than the nozzle pitch of the nozzles aligned in the steel plate width direction.

  Furthermore, in the lower surface cooling apparatus for a steel plate of the present invention, water that is shielded by the shielding plate is applied to an edge that faces the shielding edge in the width direction of the steel plate among the opening edges that define the opening. It is preferable to have a sagging drop to drop.

  Furthermore, in the steel plate lower surface cooling device of the present invention, it is preferable that the drive mechanism can change the steel plate width direction position of the shielding plate in three or more stages within the drive stroke.

  Furthermore, in the lower surface cooling apparatus for a steel sheet according to the present invention, two or more nozzle rows composed of nozzles aligned in the width direction of the steel plate are provided in the transport direction, and a shielding pattern comprising the openings on the shielding plate. It is preferable that two or more types are provided in the transport direction.

  According to the steel plate lower surface cooling method and cooling device of the present invention, the shielding edge of the opening formed in the shielding plate is inclined according to the inclination of the injection plane of the cooling water from the nozzle. Therefore, it is possible to precisely control the shielding of the nozzle, to cool the steel plate uniformly in the width direction, and to manufacture a high-quality steel plate with less material variation.

It is a front view which shows one Embodiment of the lower surface cooling apparatus of the steel plate of this invention for enforcing one Embodiment of the lower surface cooling method of the steel plate of this invention. In the lower surface cooling apparatus of the steel plate of FIG. 1, it is a top view which shows some examples which inclined the injection plane of the spray nozzle with respect to the conveyance direction. It is a top view which shows the example of the shielding board applicable to the lower surface cooling device of the steel plate of this invention, (a) is the example which inclined the shielding edge part of the shielding board to the counterclockwise side, (b) This is an example in which the shielding edge portion of the shielding plate is inclined clockwise. FIG. 6 is an enlarged plan view showing an example of a shielding plate applicable to the present invention in which the inclination angle φ of the shielding edge is made smaller than the inclination angle θ of the cooling water injection plane. FIG. 6 is an enlarged plan view showing an example of a shielding plate applicable to the present invention in which the inclination angle φ of the shielding edge is larger than the inclination angle θ of the cooling water injection plane. It is a top view which shows a mode when moving an example of the shielding board applicable to this invention to the steel plate width direction. It is a top view which shows a mode when moving another example of the shielding plate applicable to this invention to the steel plate width direction. It is a top view which shows another example of the shielding board applicable to this invention. In embodiment of the lower surface cooling device of the steel plate of this invention, it is the front view which showed a mode that the cooling water shielded with the shielding board flows along the lower surface of this shielding board. It is the front view which showed a mode that the cooling water shielded by the shielding board was guide | induced to the dredge, and flowed below. It is a schematic block diagram which shows the manufacturing line of a hot-rolled steel plate as an example which can apply the lower surface cooling device of the steel plate of this invention. It is a front view which shows an example of the conventional general steel plate lower surface cooling device. FIG. 13 is a plan view corresponding to FIG. 12. FIG. 13 is a side view corresponding to FIG. 12. It is a top view which shows a mode when the shielding board in the lower surface cooling device of the conventional steel plate is moved. FIG. 16 is a front view corresponding to FIG. 15. It is a top view which shows a mode when the shielding board is further moved from the state shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, FIG. 1 is a front view showing an embodiment of a steel sheet lower surface cooling apparatus of the present invention for carrying out an embodiment of the steel sheet lower surface cooling method of the present invention.

  The steel plate lower surface cooling device 10 of the present embodiment cools the lower surface of the hot steel plate being conveyed by a table roll after hot rolling (roll-out table roll), as shown in FIG. A plurality of spray nozzles (hereinafter simply referred to as “nozzles”) 11 arranged in the steel plate width direction are provided so as to be movable in the steel plate width direction between the nozzle 11 and the steel plate S, and the nozzles according to the amount of movement. 11 is provided with a shielding plate 12 having a plurality of openings 12a through which the cooling water sprayed from 11 is passed or shielded, and a drive device 13 that moves the shielding plate 12 close to and away from the center C in the steel plate width direction. Each nozzle 11 is connected to a lower surface cooling header 14 extending in the steel plate width direction, and cooling water is distributed therefrom. The driving device 13 is not particularly limited as long as it can move the shielding plate 12 in the width direction of the steel plate. For example, an electric actuator (linear drive mechanism), a hydraulic cylinder, a pneumatic cylinder, or the like can be used.

  In the present embodiment, the nozzle 11 is a flat spray type nozzle in which the injected cooling water spreads in a flat and fan-like manner as described above with reference to FIG. 13 and FIG. Are arranged at a predetermined pitch. The nozzle pitch is preferably about 50 to 200 mm in order to obtain a high cooling capacity. Further, as shown in FIG. 2, the injection plane of the cooling water injected from the nozzle is inclined with respect to the conveying direction in plan view so that the cooling water is injected on the entire lower surface of the steel plate, that is, with respect to the conveying direction. An inclination angle θ [rad] is formed. As shown in FIG. 14, the ejection plane is defined by two edges forming a fan angle in the fan-shaped ejection range (one edge positioned in the front as viewed in the conveying direction of the steel sheet is the front edge, and the other edge positioned in the rear is (Referred to as a trailing edge). The inclination angle θ of the ejection plane refers to an acute angle angle among angles formed with respect to the transport direction in plan view. The inclination angle θ is 0 <θ ≦ π / 2, and FIG. 2 shows several examples in which the ejection plane is inclined with respect to the transport direction. In FIG. 2, Nf is a leading edge of the injection range, Nb is a trailing edge of the injection range, N is an injection plane including the leading edge Nf and the trailing edge Nb, and w is cooling water injected from the nozzle. 2A is an example in which the injection plane N is inclined relatively large clockwise, FIG. 2B is an example in which the injection plane N is inclined relatively small clockwise, and FIG. 2C is an example in which the injection plane N is inclined. In this example, the injection plane N is inclined relatively small counterclockwise, and (d) is an example in which the injection plane N is inclined relatively large counterclockwise.

  And in this embodiment, as shown in FIG. 3, among the opening edges that define the opening 12a of the shielding plate 12, the shielding edge 12a1 that shields the cooling water w according to the amount of movement of the shielding plate 12 is: It is inclined to the same side as the inclined side of the ejection plane N with respect to the transport direction. For example, in the example shown in FIG. 3A, since the injection plane N of the cooling water w is inclined counterclockwise with respect to the transport direction, the shielding edge 12a1 of the shielding plate 12 is also counterclockwise. In the example shown in FIG. 3B, since the injection plane N of the cooling water w is inclined clockwise with respect to the transport direction, the shielding edge 12a1 of the shielding plate 12 is also inclined clockwise. doing. In this way, by inclining the shielding edge 12a1 of the shielding plate 12 in accordance with the inclination direction of the injection plane N of the cooling water w, the cooling water shielding control can be performed for each nozzle, and a wide range of plate widths can be achieved. Thus, the steel sheet S can be uniformly cooled in the width direction. In order to make this more reliable, when the inclination angle of the shielding edge 12a1 with respect to the transport direction is φ [rad], the inclination angle φ is the inclination of the injection plane of the cooling water w injected from the nozzle 11. It is preferable to set so as to satisfy 0 <φ <arctan (2 tan θ) in relation to the angle θ [rad]. Of the opening edges that define the opening 12a, the opposite edge 12a2 opposite to the shielding edge 12a1 may be parallel to the transport direction, but is inclined to the same side as the shielding edge 12a1 as shown in the example of the drawing. In this case, the opening area of the shielding plate 12 can be reduced, so that the strength of the shielding plate 12 can be increased.

  When the shielding plate 12 has a shielding pattern as shown in FIG. 3, the length of the cooling water w sprayed from the nozzle 11 in the width direction at the opening passage position (the length along the steel plate width direction) is L. The minimum stroke required to shift the shielding plate 12 by one level, that is, to change the state of the cooling water w passing through the opening 12a from full injection to half injection, as shown in FIG. 1−tan φ / tan θ) · L / 2, and when θ <φ, as shown in FIG. 5, (tan φ / tan θ−1) · L / 2. In the case of θ = φ, there is no partial shielding of the cooling water, and the pattern is a complete shielding from all injections. The minimum stroke required when the shielding plate 12 is shifted by one level is the width of the cooling water w when passing through the opening. It becomes equal to the direction thickness d (FIG. 6). In general, since the thickness in the width direction of the flat spray type cooling water (spray water) w is about 10 mm, the cooling water can be shut off with a very short stroke. That is, as an example in FIG. 6, when the nozzle pitch is 100 mm, the width d of the cooling water w is 10 mm, and the width dimension of the opening 12 is 10 mm longer from the outer side to the inner side in the steel plate width direction, Each time the plate 12 is moved 10 mm outward in the steel plate width direction, the cooling water w that is shielded increases from the end in the steel plate width direction one by one. At this time, since the nozzle pitch is 100 mm, the shielding pattern can be divided into 10 stages including full width injection, and can correspond to a plate width of 600 to 2400 mm of a general hot-rolled steel sheet, and the driving stroke is 90 mm. Because it is short, stable operation can be expected.

  In addition, the angle φ formed by the shielding edge 12a1 of the shielding plate 12 with respect to the conveyance direction is set to 0 <φ <arctan (2 tan θ), so that the cooling water w can be shielded with a short stroke. That is, if the minimum stroke required for shifting the shielding plate 12 by one level is less than L / 2, the cooling water w can be shielded with a shorter stroke than the conventional short opening, Cooling water shielding control is possible, and the steel plate width direction can be uniformly cooled over a wide range of plate widths. When φ <θ, 0 <φ, and when θ <φ, tanφ / tanθ-1 <1, that is, 0 <φ <arctan (2 tanθ). Thus, for example, as shown in a plan view of the cooling water w by the shielding plate 12 at each stage, the shielding control of each nozzle is facilitated, and the nozzle 11 at the center in the steel plate width direction is shielded. Therefore, it is possible to shield only the nozzle 11 at the end in the steel plate width direction without depending on the plate width. In order to reduce the stroke required for shielding and facilitate the shielding control performance of each nozzle, it is preferable that φ is 5 ÷ 180 × π ≦ φ ≦ arctan (2 tan θ) −5 ÷ 180 × π. More preferably, = θ. “5 ÷ 180 × π” is expressed in 5 ° radians.

  Moreover, according to this embodiment, since the drive stroke of the drive mechanism 13 can be shortened, there exists an advantage that the drive mechanism 13 can be arrange | positioned in the width direction outer side of the shielding board 12. FIG. As a result, scattering of the cooling water w to the drive device 13 can be prevented, and the drive device 13 can be stably driven over a long period of time.

  Moreover, by providing two or more types of width direction dimensions of the openings 12 aligned in the steel plate width direction, a shielding pattern corresponding to a plurality of steel plate widths can be provided, preferably three or more types, more preferably four types. By providing as described above, the steel plate can be uniformly cooled in the width direction with respect to a wide range of plate widths.

  In the above-described embodiment, an example in which only one row of nozzle rows arranged in the steel plate width direction is arranged between the table rolls with respect to the nozzles 11 installed on the lower surface side of the steel plate S has been described. Even when the row is installed between a plurality of table rolls, the same effect can be obtained by installing the shielding plate 12 having the opening 12 a above the nozzle 11. Further, even when two or more nozzle rows are installed between the table rolls, the openings 12a of the shielding plate are formed so that the nozzles 11 are arranged in three rows in a staggered manner in FIG. Similar effects can be obtained by making each nozzle 11 correspond to the case where the number of nozzle rows is one.

  Further, when the shielding plate 12 is simply provided with the opening 12a, the cooling water blocked by the shielding edge portion 12a1 of the shielding plate 12 as shown in FIG. It flows to the center side in the width direction of the steel sheet and interferes with the cooling water w injected from the adjacent nozzle 11 on the center side in the width direction. May be slightly non-uniform. For this reason, it is preferable to provide the drooping ridge 12b on the opposing edge 12a2 that faces the shielding edge 12a1 in the width direction of the steel plate among the opening edges that define the opening 12 as shown in FIG. Since the cooling water flowing along the plate 12 can collide with the dripping rod 12b and be dropped, the interference with the cooling water w ejected from the adjacent nozzle 11 described above can be avoided and the cooling water w can be stabilized. Can be injected. In FIG. 10, the hanging rod 12b is provided only on the opposing edge portion 12a2, but the hanging rod 12b may be provided on the entire periphery of the shielding edge portion 12a1 or the opening edge.

  Furthermore, although illustration is omitted, when two or more nozzle rows composed of a plurality of nozzles 11 aligned in the steel plate width direction are provided in the transport direction, two or more types of shielding patterns composed of the openings 12a are provided in the transport direction. Preferably, according to this, the steel plate width direction can be uniformly cooled with respect to a wider range of plate widths. For example, when 10 nozzle rows in which nozzles (thickness d in the width direction of the injected cooling water w are 10 mm) 11 are arranged in the steel plate width direction at a nozzle pitch of 100 mm are arranged in the transport direction, the steel plate width is 600 to 2400 mm. Of the opening 12a, the width of the opening 12a is 5 rows having a shielding pattern that is longer by 10 mm from the outer side to the inner side in the width direction of the steel plate, the width of the opening 12a that can correspond to the width of the steel plate 2400 to 4200 mm. By arranging five rows having a shielding pattern whose width direction dimension is 10 mm longer from the outer side to the inner side in the width direction of the steel plate, the steel plate can be uniformly cooled in the width direction with respect to a wide range of plate widths. .

  One embodiment of the steel sheet lower surface cooling method of the present invention can be realized by using the above-described steel sheet lower surface cooling device, that is, the steel sheet lower surface cooling method of the present embodiment is hot-rolled. A lower surface cooling method for a steel plate that cools the lower surface of a hot steel plate S that is being conveyed by a subsequent table roll, the steel plate being aligned in the width direction of the steel plate, each of which injects the cooling water w in a fan shape and a fan-shaped injection range. The injection plane N including the front edge Nf and the rear edge Nb is provided so as to be movable in the steel plate width direction between the nozzles 11 and the steel plate S, and the amount of movement thereof. And a plurality of openings 12a through which the cooling water jetted from the nozzles 11 passes or is shielded according to the amount of movement of the shielding plate 12 among the opening edges that define the openings 12a. According to cooling The shielding edge 12a1 that shields w is used with the shielding plate 12 inclined to the same side as the inclined side of the ejection plane N with respect to the transport direction, and the shielding plate 12 is made to the steel plate width direction center C according to the steel plate width. A part or all of the cooling water from the nozzle 11 on the end side in the width direction of the steel sheet is shielded by being closely spaced.

  According to the lower surface cooling method of the steel plate of the present embodiment, the cooling edge shielding control for each nozzle is performed by inclining the shielding edge 12a1 of the shielding plate 12 in accordance with the inclination direction of the injection plane N of the cooling water w. It becomes possible, and the steel plate S can be uniformly cooled in the width direction with respect to a wide range of plate widths.

  Moreover, in the lower surface cooling method of the steel plate of the present embodiment, when the inclination angle of the shielding edge 12a1 with respect to the conveying direction is φ [rad], the inclination angle φ is the injection plane N of the cooling water w injected from the nozzle 11. It is preferable to set so as to satisfy 0 <φ <arctan (2 tan θ) in relation to the inclination angle θ [rad] of the cooling water. According to this, even if the moving amount (stroke) of the shielding plate 12 is small, the cooling water A reliable shielding of w is possible.

(Example)
Examples of the present invention will be described below.

  A hot-rolled steel sheet having a thickness of 15 mm was manufactured from a slab having a thickness of 250 mm using a production line for hot-rolled steel sheets as shown in FIG. Specifically, after the slab having a thickness of 250 mm is reheated in a heating furnace, the primary scale is removed by descaling, the slab is roughly rolled to a thickness of 50 mm by a roughing mill, and then finished to a thickness of 15 mm by a finishing mill. The hot-rolled steel sheet was rolled to obtain a hot-rolled steel sheet, and then the hot-rolled steel sheet was cooled during conveyance on the run-out table and wound with a coiler. The plate width that can be produced in this production line is 600 mm at the minimum and 2000 mm at the maximum. In this embodiment, the plate width is cooled from 900 ° C. to 550 ° C. during the conveyance on the run-out table, and the plate width is 600 mm, 1200 mm, and 2000 mm. did.

  In the run-out table, the upper surface of the steel plate was cooled by a hairpin laminar type upper cooling device, and the lower surface of the steel plate was cooled by a flat spray type lower surface cooling device. Moreover, the width | variety of an upper surface and a lower surface cooling device can inject a cooling water in the range of 2000 mm of plate width so that it can cool to the maximum plate width. Moreover, the temperature distribution of the steel plate before and after cooling can be measured with a radiation thermometer.

  The cooling water injection conditions of the bottom surface cooling device are: the distance from the nozzle injection port to the steel plate bottom surface is 150 mm, the spray spread angle (fan angle) from the nozzle central axis is 70 °, the nozzle width direction pitch is 100 mm, and per nozzle Was 30 L / min, and the inclination angle θ of the cooling water injection plane with respect to the conveying direction was 30 °.

  In the inventive examples 1 to 6, as shown in FIG. 1, the shielding plate 12 having the opening 12a is installed above the nozzle 11 of the lower surface cooling device 10, and the shielding plate 12 is moved in the steel plate width direction. The driving device 13 was installed on the outer side in the width direction of the spray nozzle row, and the lower surface of the steel plate was cooled. The width L in the width direction of the cooling water when passing through the opening was 50 mm, and the thickness d in the width direction of the jet cooling water w was 10 mm (see FIGS. 5 and 6). In the case of a plate width of 2000 mm, since the plate width and the lower surface cooling water injection width (spray nozzle row width) are the same, the lower surface cooling water does not spray upward, and the lower surface cooling water is directly applied to the end surface in the width direction of the steel plate. There was no collision, and no supercooling occurred at the end in the width direction of the steel sheet.

  In order to obtain a predetermined material, it is necessary to set the temperature deviation ΔT between the width direction center portion and the width direction end portion of the steel sheet to be within 40 ° C., and considering variation in manufacturing conditions, it is preferable to be within 30 ° C., It is even better if it is within 20 ° C. Material failure occurs when 40 ° C <ΔT, so it is not possible (indicated by the symbol “x”). At 30 ° C <ΔT ≦ 40 ° C, the material and temperature uniformity satisfy the standard, but are acceptable because there is some variation (the symbol “ 20 ° C. <ΔT ≦ 30 ° C. is good because the material and temperature uniformity are both good (indicated by the symbol “◯”), and ΔT ≦ 20 ° C. is material and temperature uniformity. Since it was very good, it was evaluated as excellent (indicated by symbol “「 ”). Table 1 shows the conditions including the inclination angle φ of the shielding edge 12a1 of the shielding plate 12 with respect to the conveyance direction, together with the evaluation results.

  Each of Invention Examples 1 to 6 satisfies 0 <φ <arctan (2 tan θ), and ΔT is within 30 ° C. in any plate width, and manufactures a high-quality steel plate with little material variation. I was able to. In particular, Invention Examples 2 to 4 satisfied 5 ÷ 180 × π ≦ φ ≦ arctan (2 tan θ) −5 ÷ 180 × π, and the temperature deviation became smaller. Furthermore, since the invention example 5 is (phi) = (theta), the cooling water shielding control in each nozzle is attained, the steel plate width direction can be cooled uniformly with respect to a wide plate width, and high quality with little material variation Steel sheets can be manufactured. In Invention Example 6, the drooping gutter 12b is installed in the vertical direction so that the cooling water falls downward on the central side of the opening edge portion in the steel plate width direction, so that the steel plate width direction can be cooled more uniformly. It was.

  Comparative Example 1 is a hot-rolled steel sheet manufactured under the same conditions as in Invention Examples 1 to 6 except that it does not have a shielding plate. In a hot-rolled steel sheet with a plate width of 600 mm and 1200 mm, the end in the width direction of the steel sheet The edge of the steel sheet in the width direction was overcooled due to the direct impact of the cooling water sprayed and dropped from the outside and the lower surface cooling water on the width direction end face of the steel sheet, and a predetermined material could not be obtained.

  In Comparative Examples 2 to 4, 0 <φ <arctan (2 tan θ) is not satisfied, and the stroke amount necessary for shifting by one level is large. Therefore, it is difficult to control the shielding of each nozzle. As a result, not only the outer side of the nozzle but also the inner nozzle was half-shielded, and the half-shielded jet cooling water collided with the lower surface of the steel plate, resulting in uneven cooling at the end in the steel plate width direction. In Comparative Example 2, although ΔT was within 40 ° C., the cooling uniformity was slightly inferior compared with the case where 0 <φ <arctan (2 tan θ) was satisfied. In Comparative Example 3 and Comparative Example 4, the stroke for shifting one level was too large with respect to the nozzle pitch, so that a shielding pattern corresponding to each plate width could not be made, and ΔT became large.

  As mentioned above, although this invention was demonstrated based on drawing, this invention is not limited to the above-mentioned embodiment, A various change is possible. For example, in the above-described embodiment, the cooling of the lower surface of the hot-rolled steel sheet during conveyance at the run-out table has been described, but the present invention is not limited to this, and can be applied to the controlled cooling of the thick steel sheet, The present invention can also be applied to cooling when rolling thick steel plates and hot-rolled steel plates.

  ADVANTAGE OF THE INVENTION According to this invention, it became possible to provide the technique which implement | achieves the supercooling prevention of the width direction edge part of a steel plate, and can ensure a high quality steel plate with few material dispersion | variation.

DESCRIPTION OF SYMBOLS 10 Steel plate lower surface cooling device 11 Spray nozzle 12 Shielding plate 12a Opening portion 12a1 Shielding edge portion 12a2 Opposing edge portion 12b Dripping rod 13 Drive device 14 Lower surface cooling header N Injection plane Nf Front edge of cooling water injection range Nb Injection of cooling water Range trailing edge S Steel plate w Cooling water θ Inclination angle of spray plane relative to transport direction φ Inclination angle of shielding edge relative to transport direction

Claims (8)

A method of cooling the lower surface of a steel plate that cools the lower surface of the steel plate being conveyed,
A plurality of nozzles that are aligned in the width direction of the steel sheet, each of which sprays cooling water in a fan shape, and the spray plane including the front and rear edges of the fan-shaped spray range is inclined with respect to the transport direction;
A shielding plate having a plurality of openings that are provided so as to be movable in the width direction of the steel plate between the nozzle and the steel plate, and allow or pass the cooling water sprayed from the nozzle according to the amount of movement. A shielding plate that shields cooling water according to the amount of movement of the shielding plate among the opening edges that define the opening, and is inclined to the same side as the inclined side of the ejection plane with respect to the transport direction; Use
By shielding and separating the shielding plate with respect to the steel plate width direction center according to the steel plate width, a part or all of the cooling water from the nozzle on the end side in the steel plate width direction is shielded ,
When the inclination angle of the shielding edge with respect to the conveying direction is φ [rad] and the inclination angle of the ejection plane with respect to the conveying direction is θ [rad], the inclination angle φ of the shielding edge is 0 <φ <arctan A method of cooling the lower surface of the steel sheet, wherein the setting is made to satisfy (2 tan θ) . The method for cooling the lower surface of a steel sheet according to claim 1, wherein two or more types in the width direction of the opening are provided. A steel sheet lower surface cooling device for cooling the lower surface of the steel sheet being conveyed,
A plurality of nozzles that are aligned in the width direction of the steel sheet, each of which sprays cooling water in a fan shape, and the spray plane including the front and rear edges of the fan-shaped spray range is inclined with respect to the transport direction;
A shielding plate having a plurality of openings that are provided so as to be movable in the steel plate width direction between the nozzle and the steel plate, and allow or pass cooling water sprayed from the nozzle according to the amount of movement;
A drive mechanism for moving the shielding plate in the width direction of the steel plate,
Among the opening edges that define the opening, the shielding edge that shields the cooling water according to the amount of movement of the shielding plate is inclined to the same side as the inclined side of the ejection plane with respect to the transport direction, and the transport direction The angle of inclination of the shielding edge is φ [rad], and the angle of inclination of the ejection plane with respect to the transport direction is θ [rad]. The inclination angle φ of the shielding edge is 0 <φ <arctan (2 tan θ ) Is set so as to satisfy the above) . The lower surface cooling apparatus of the steel plate according to claim 3 , wherein two or more types in the width direction of the opening are provided. The steel plate lower surface cooling device according to claim 3 or 4 , wherein the drive mechanism has a drive stroke less than a nozzle pitch of nozzles aligned in the steel plate width direction. Of opening edges defining the said opening, the opposing edges at the shielding edge and the steel plate width direction, having a sagging flange dropping the water that has been shielded by the shielding plate, any one of claims 3-5 The lower surface cooling apparatus of the steel plate as described in one item | term. The steel plate lower surface cooling device according to any one of claims 3 to 6 , wherein the drive mechanism is capable of changing the steel plate width direction position of the shielding plate in three or more stages within the drive stroke. Two or more nozzle rows composed of nozzles aligned in the width direction of the steel plate are installed in the transport direction, and there are two types of shielding patterns on the shield plate determined by the pitch of the openings and the width direction dimensions of the openings in the transport direction. The lower surface cooling apparatus for a steel sheet according to any one of claims 3 to 7 , wherein the apparatus is provided as described above.