JP6939157B2 - Hot-rolled steel sheet cooling device and hot-rolled steel sheet cooling method - Google Patents

Description

The present invention relates to a cooling device for cooling the lower surface of a hot-rolled steel sheet transported on a transport roll after finish rolling in a hot rolling step, and a cooling method using the cooling device.

With the recent weight reduction of automobiles, the demand for high-strength steel sheets among hot-rolled steel sheets is increasing, and the quality required for hot-rolled steel sheets is further increasing. Especially in recent years, not only high strength but also excellent workability such as press formability and hole expansion, and variation in mechanical properties such as tensile strength and workability are kept within a predetermined range over the entire area of the steel sheet. That is also required.

In the manufacturing process of hot-rolled steel sheets, winding temperature is one of the factors that greatly affect the characteristics of the final product as described above. Therefore, in order to improve the quality of the steel sheet, it is important to improve the uniformity of the winding temperature over the entire area of the steel sheet. In particular, even if the steel sheet is uniformly cooled in the plate width direction, the winding temperature at both ends of the hot-rolled steel sheet in the plate width direction is lower than that of the other parts. Uniformity is important. Here, the take-up temperature is the temperature of the steel sheet immediately before the take-up device when the steel sheet is taken up after the cooling step after finish rolling.

The reason why the winding temperature of both ends of the hot-rolled steel sheet in the plate width direction is lower than that of the other parts is that the temperature of the entire steel sheet gradually decreases in the rolling process after being extracted from the heating furnace. At this time, there is no high-temperature steel material next to the central part of the steel sheet at both ends, but rather the end face of the sheet acts as a heat-dissipating point. The temperature at both ends in the width direction of the sheet is lower than that of other parts, and there is already a temperature difference, and the temperature difference immediately after rolling may be promoted in the cooling process. Further, the above temperature difference becomes more remarkable when the winding temperature is low.

The winding temperature of the hot-rolled steel sheet in the plate width direction can be made uniform by the cooling device disclosed in Patent Documents 1 to 3.
In the cooling device disclosed in Patent Document 1, cooling water headers in which cooling water injection holes are arranged in the plate width direction of the hot-rolled steel sheet are arranged facing each other above and below the hot-rolled steel sheet, and the plate width is described on both sides of the cooling water header. Built-in masking unit that moves along the direction. In this cooling device, the cooling water injection from the cooling water injection hole is blocked by the masking unit, and the cooling water injection width is controlled.

Further, in the cooling device disclosed in Patent Document 2, the cooling water header provided below the transport roller has a double structure of an inner pipe and an outer pipe, and the inner pipe is rotatably supported by the outer pipe to be outside. Cooling water nozzles are arranged in the pipe along the plate width direction of the hot-rolled steel plate, and the inner pipe is provided with a plurality of through holes that can communicate with the cooling water nozzles along the plate width direction. In this cooling device, the cooling water injection range can be changed by supplying the cooling water to the inner pipe, fixing the outer pipe, rotating the inner pipe, and adjusting the amount of rotation. Specifically, the lengths of the plurality of through holes provided in the inner pipe in the circumferential direction are different from each other, and in the cooling water header, the through holes do not communicate with the cooling water nozzle on the end side, and the nozzle is concerned. While it is possible to prevent the injection of cooling water from the hot-rolled steel plate, the through hole is communicated with the cooling water nozzle on the central side to enable the injection of cooling water from the nozzle. The injection range of the cooling water in the plate width direction is changed.

In the cooling device disclosed in Patent Document 3, the end portion in the width direction is supercooled by preventing the cooling water injected from the cooling water header for cooling the lower surface of the hot-rolled steel sheet from wrapping around the upper surface of the hot-rolled steel sheet. The hot-rolled steel sheet is cooled uniformly in the plate width direction. In this cooling device, the cooling water header is provided with a perforated shielding plate having a plurality of holes through which cooling water from the cooling water nozzle of the cooling water header can pass, and is movable in the plate width direction. The hole size in the width direction is less than the nozzle pitch in the same direction, and the hole size becomes larger toward the center side from the center side to the end side in the same direction. Therefore, by separating the perforated shielding plate from the center of the through plate according to the plate width, part or all of the cooling water from the cooling water nozzle on the end side in the plate width direction is blocked, and the hot-rolled steel plate is used. It is possible to prevent the cooling water from wrapping around the upper surface of the steel plate.

Japanese Unexamined Patent Publication No. 2016-215261 Japanese Unexamined Patent Publication No. 2015-160240 Japanese Unexamined Patent Publication No. 2012-91194

By the way, the hot-rolled steel sheet may meander during transportation on the transfer roller. The reasons for meandering are that the plate plane is not flat due to poor maintenance of the transport roller, and that the temperature is uneven during cooling and the local plate shrinkage difference is due to the widthwise plate thickness deviation during rolling and the scale residual distribution on the steel plate surface. May occur.

However, in the cooling device disclosed in Patent Documents 1 to 3, the case where the hot-rolled steel sheet is meandering is not considered as described above, and in Patent Documents 1 to 3, heat is generated even when the hot-rolled steel sheet is meandering. No disclosure or suggestion has been made regarding making the winding temperature of the rolled steel sheet uniform in the plate width direction, that is, making the temperature of the hot-rolled steel sheet in the plate width direction uniform when the hot-rolled steel sheet is meandering.

The present invention has been made in view of the above circumstances, and even if the hot-rolled steel sheet is meandered by appropriately cooling the lower surface of the hot-rolled steel sheet after finish rolling in the hot-rolling process, the present invention is concerned. The purpose is to improve the temperature uniformity in the width direction of the hot-rolled steel sheet.

The present invention that solves the above problems is a cooling device that cools the lower surface of a hot-rolled steel sheet that is transported on a transport roll to a winding device after finish rolling in a hot rolling process, and is a cooling device that cools the lower surface of a steel plate transport region. The entire region in the plate width direction and the cooling region defined by the predetermined length in the rolling direction are defined as the total cooling region, and one of the regions at both ends of the total cooling region in the plate width direction is the first end side cooling region and the other. Is a second end-side cooling region, and each of the first end-side cooling region and the second end-side cooling region is divided into a plurality of cooling regions in the plate width direction, which is width division cooling. A band, a divided cooling surface which is a cooling region obtained by dividing the width-divided cooling zone into a plurality of parts in the rolling direction, and at least one cooling water nozzle for injecting cooling water onto each lower surface of the divided cooling surface. , A switching device for switching between collision and non-collision of the cooling water injected from the cooling water nozzle with the divided cooling surface, and information for detecting the position of the end portion of the hot-rolled steel sheet in the plate width direction. An end detection device to be acquired and a control device that detects the position of the end portion in the plate width direction based on the information and controls the operation of the switching device based on the detection result are provided . The cooling device is provided between a water supply header for supplying cooling water and a drainage header or drainage area for draining the cooling water, which is provided in a pipe through which the cooling water supplied to the cooling water nozzle flows. a three-way valve for switching the flow of water, wherein the three-way valve, the transport roll is provided in an the side of the plate width direction, as the characteristic that they are being placed at the same height as the tip of the cooling water nozzles There is.

It is preferable that one or more cooling water nozzles corresponding to the divided cooling surfaces are arranged in the cooling water nozzles.

It is preferable that the lengths of the divided cooling surfaces included in the width-divided cooling zone in the rolling direction are the same in the rolling direction.

The length of the divided cooling surface in the rolling direction is preferably a multiple of the length between the transport rolls.

In each of the first end-side cooling region and the second end-side cooling region, the arrangement of the plurality of the cooling water nozzles in the plate width direction is such that the distance between the centers of the cooling water nozzles adjacent to each other in the plate width direction is large. It is preferable that they are all arranged equidistantly.

It is preferable that the end detection device is provided on both the upstream side in the rolling direction and the downstream side in the rolling direction of the cooling region.

According to the present invention from another viewpoint, it is a cooling method for cooling the lower surface of a hot-rolled steel sheet transported on a transport roll to a winding device after finish rolling in a hot rolling process, and is a cooling method for cooling the lower surface of a steel plate transport region. The entire region in the plate width direction and the cooling region defined by the predetermined length in the rolling direction are defined as the total cooling region, and one of the regions at both ends in the plate width direction of the total cooling region is the first end side cooling region. The other is a second end-side cooling region, and each of the first end-side cooling region and the second end-side cooling region is divided into a plurality of parts in the plate width direction, and each cooling region is divided into widths and cooled. A band is used, and a cooling region obtained by dividing the width-divided cooling band into a plurality of parts in the rolling direction is used as a divided cooling surface. Based on this, the cooling water is supplied to the hot-rolled steel sheet by the cooling water nozzle for each of the divided cooling surfaces so that the cooling water collides with and does not collide with the hot-rolled steel plate. A three-way valve that switches the flow of the cooling water between the water supply header to be rolled and the drainage header or drainage area for draining the cooling water, and is provided on the side of the transport roll in the plate width direction and described above. It is characterized by being controlled by a switching device equipped with a three-way valve arranged at the same height as the tip of the cooling water nozzle.

According to the present invention, by appropriately cooling the lower surface of the hot-rolled steel sheet after finish rolling in the hot-rolling process, even when the hot-rolled steel sheet is meandered, the temperature in the plate width direction of the hot-rolled steel sheet is reached. It is possible to improve the uniformity of.

It is explanatory drawing which shows the outline of the structure of the hot rolling equipment 10. It is a perspective view which shows the outline of the structure of the lower width direction control cooling device 17 which concerns on this embodiment. It is a side view which shows the outline of the structure of the lower width direction control cooling device 17 which concerns on this embodiment. It is a top view which shows the outline of the structure of the lower width direction control cooling device 17 which concerns on this embodiment. It is a figure explaining one example of the divided cooling surface A5. It is explanatory drawing which paid attention to the width division cooling zone A4. It is a figure explaining the division cooling surface A5 of another example. It is a figure explaining the arrangement of the divided cooling surface A5, the cooling water nozzle 25, and the end detection devices 32, 33 in the lower width direction control cooling device 17 which concerns on this embodiment. This is an example of the arrangement of the divided cooling surface A5 and the cooling water nozzle 25. This is an example of the arrangement of the divided cooling surface A5 and the cooling water nozzle 25. This is an example of the arrangement of the divided cooling surface A5 and the cooling water nozzle 25. It is a figure for demonstrating the control performed by the control device 31. It is a figure for demonstrating the control performed by the control device 31. It is a figure explaining the structure of the lower width direction control cooling device 17 of the example which does not have an intermediate header 26. It is a figure which showed a part of the temperature distribution of the upper surface of the steel sheet in the case of the comparative example 1. It is a figure which showed a part of the temperature distribution of the upper surface of the steel sheet in the case of Example 1. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

FIG. 1 is an explanatory diagram showing an outline of the configuration of a hot-rolled steel sheet manufacturing apparatus (hereinafter, referred to as “hot rolling equipment”) 10 provided with a cooling apparatus according to the present embodiment.

In the hot rolling equipment 10, the heated slab 1 is sandwiched between rolls up and down and continuously rolled, thinned to a minimum plate thickness of about 1 mm, and wound as a hot-rolled steel plate 2. The hot rolling equipment 10 includes a heating furnace 11 for heating the slab 1, a width rolling mill 12 for rolling the slab 1 heated in the heating furnace 11 in the plate width direction, and rolling in the plate width direction. A rough rolling mill 13 that rolls the slab 1 from the vertical direction to make a rough bar, a finishing rolling mill 14 that continuously hot-finish rolls the rough bar to a predetermined thickness, and the finishing rolling mill 14 heats the rough bar. Cooling devices 15, 16 and 17 for cooling the interfinished rolled hot-rolled steel sheet 2 with cooling water, and a winding device 19 for winding the hot-rolled steel sheet 2 cooled by the cooling devices 15, 16 and 17 in a coil shape. It has. Of the cooling devices 15, 16 and 17, the upper cooling device 15 is arranged above the hot-rolled steel plate 2 to which the runout table is conveyed, and the lower cooling device 16 and the lower width direction control cooling device 17 are hot-rolled steel sheets 2. It is located below.

In the heating furnace 11, a process of heating the slab 1 carried in from the outside through the inlet to a predetermined temperature is performed. When the heat treatment in the heating furnace 11 is completed, the slab 1 is extracted to the outside of the heating furnace 11 and transferred to the rolling process by the rough rolling mill 13 via the width rolling mill 12.

In the rough rolling step, the slab 1 is rolled by the rough rolling mill 13 into a rough bar (sheet bar) having a thickness of about 30 mm to 60 mm, and is conveyed to the finishing rolling mill 14.

In the finish rolling mill 14, the conveyed rough bar is rolled to a plate thickness of about several mm to obtain a hot-rolled steel sheet 2. The finish-rolled hot-rolled steel sheet 2 is conveyed by a transfer roll 18 (see FIGS. 2 to 4), and is first sent to a cooling zone including an upper cooling device 15 and a lower width direction control cooling device 17. Further, it is sent to a cooling zone including an upper cooling device 15 and a lower cooling device 16.

The hot-rolled steel sheet 2 is cooled by the upper cooling device 15, the lower cooling device 16, and the lower width direction control cooling device 17, and is wound into a coil by the winding device 19.

The configuration of the upper cooling device 15 is not particularly limited, and a known cooling device can be applied. For example, the upper cooling device 15 has a plurality of cooling water nozzles that inject cooling water vertically downward from above the hot-rolled steel sheet 2 toward the upper surface of the hot-rolled steel sheet 2. As the cooling water nozzle, for example, a slit laminar nozzle, a pipe laminar nozzle, or the like is used. The upper cooling device 15 is preferably provided from the viewpoint of ensuring the cooling capacity, and is not always arranged when the cooling is not insufficient, but it is usually required.
The lower cooling device 16 injects cooling water vertically upward toward the lower surface of the hot-rolled steel sheet 2 from below the hot-rolled steel sheet 2 transported on the transport roll 18 of the run-out table to press the hot-rolled steel sheet 2. It is a cooling device for cooling, and a known cooling device can be applied without particular limitation on its configuration.

Next, the configuration of the lower width direction control cooling device 17 will be described. FIG. 2 is a perspective view schematically showing a part of the configuration of the lower width direction control cooling device 17, and FIG. 3 is a plate width schematically showing a part of the configuration of the lower width direction control cooling device 17. A side view seen from the direction (Y direction), and FIG. 4 shows a plan view seen from above in the vertical direction (Z direction), which schematically shows a part of the configuration of the lower width direction control cooling device 17.
The lower width direction control cooling device 17 in the present embodiment includes a lower central portion cooling device 20 and a lower end portion cooling device 21.

The lower central portion cooling device 20 cools vertically upward from below the hot-rolled steel sheet 2 transported on the transport roll 18 of the runout table toward the lower surface of the hot-rolled steel sheet 2 located in the central region A3 described later. It is a general cooling device that injects water to cool the hot-rolled steel sheet 2, and its configuration is not particularly limited. For example, the lower central portion cooling device 20 has a plurality of cooling water nozzles 22 that inject cooling water vertically upward from below the hot-rolled steel plate 2 toward the lower surface of the hot-rolled steel plate 2, and further, the cooling water nozzle 22. It has a header 23 for supplying cooling water to the water supply and a pipe 24 for connecting the header 23 and the water supply header 29 described later, and the lower cooling is controlled on and off. As the cooling water nozzle 22, for example, a slit laminar nozzle, a pipe laminar nozzle, or the like is used.

The lower end cooling device 21 includes a cooling water nozzle 25, a switching device including an intermediate header 26, a pipe 27, a water supply header 29, a three-way valve 28, and a drainage header 30, and end detecting devices 32 and 33. It is roughly configured with a control device 31.

The lower end cooling device 21 has a width-divided cooling zone A4 as a cooling surface formed by dividing both ends of the total cooling region A1 which is the lower surface of the steel plate transport region, which will be described later, in the plate width direction. Is a device that controls cooling with respect to the divided cooling surface A5 when the cooling region obtained by dividing the above into a plurality of parts in the rolling direction is defined as the divided cooling surface A5. Figures 5 to 7 show figures for the explanation. 5 and 7 are views for explaining the divided cooling surface A5. 5 and 7 are views of the hot rolling equipment 10 viewed from the Z direction, and show the relationship between the total cooling region A1 and the position of the transfer roll 18, which will be described later. In FIGS. 5 to 7, the transport roll 18 is shown by a dotted line for convenience of explanation.

In the present embodiment, the region that can exist when the hot-rolled steel plate 2 that can be manufactured by the hot rolling equipment 10 is transported on the runout table is referred to as a “steel plate transport region”. The "steel plate transport region" is a three-dimensional region defined by the maximum plate thickness x (maximum plate width + maximum meandering width) of the hot-rolled steel sheet that can be manufactured and extends in the rolling direction. Therefore, the "steel plate transport region" occupies the region from the exit side end of the finish rolling mill on the runout table to the front of the take-up apparatus in the rolling direction.

Of the lower surface of the "steel plate transport region", the region to be cooled by the lower width direction control cooling device 17 and defined by the entire region in the plate width direction and the predetermined length in the rolling direction is "total cooling". Area A1 ”.

The “total region in the plate width direction” indicates a region where the hot-rolled steel sheet 2 can exist on the transport roll 18. The "predetermined length in the rolling direction" is at least one pitch or more of the transport roll 18. The length of the "predetermined length in the rolling direction" is not particularly limited, but the length of the "predetermined length in the rolling direction" is, for example, the total length of the runout table (winding from the exit side end of the finishing rolling mill). It is 1/8 to 1/2 of the length to the front of the device). This is set because the temperature drop allowance of the entire steel sheet in the run-out table is about 200 to 800 ° C., and the temperature deviation between the temperature at both ends and the temperature deviation at the center is about 100 ° C. or less.

As shown in FIG. 5, one of the regions at both ends in the plate width direction of the total cooling region A1 is designated as "first end-side cooling region A2 ₁ " and the other is designated as "second end-side cooling region A2 ₂ ". The region of the cooling region A1 sandwiched between the first end-side cooling region A2 ₁ and the second end-side cooling region A2 ₂ is referred to as a "central region A3".
Further, each cooling region obtained by dividing each of the first end-side cooling region A2 ₁ and the second end-side cooling region A2 ₂ into a plurality of parts in the plate width direction is referred to as a "width-divided cooling zone A4". FIG. 6 shows an example in which the first end-side cooling region A2 ₁ and the second end-side cooling region A2 ₂ are each divided into a plurality of width-divided cooling zones A4. The number of width-divided cooling zones A4 (that is, the number of divisions) in the plate width direction is not particularly limited, but in the example of FIG. 6, each of the end-side cooling regions A2 ₁ and A2 ₂ is divided into four widths. It is divided into bands A4.

The length of the width-divided cooling zone A4 in the plate width direction is such that the length in the plate width direction of each of the first end-side cooling region A2 ₁ and the second end-side cooling region A2 ₂ of the steel plate transport region A1 is divided. The length is divided by the number. The length of the width-divided cooling zone A4 in the plate width direction is not particularly limited, and may be appropriately set such as 50 mm or 100 mm.

Each cooling region obtained by dividing the width-divided cooling zone A4 into a plurality of parts in the rolling direction is referred to as a "divided cooling surface A5". The length of the divided cooling surface A5 in the plate width direction is the same as the length of the width divided cooling zone A4 in the plate width direction, and the length of the divided cooling surface A5 in the rolling direction divides the length of the width divided cooling zone A4 in the rolling direction. It is the length divided by the number.
The length of the divided cooling surface A5 in the rolling direction is not particularly limited and can be set as appropriate. The length of the divided cooling surface A5 shown in FIG. 5 in the rolling direction is set to be the same as one pitch of the transport roll 18. Further, FIG. 7 shows an example in which the length of the divided cooling surface A5 in the rolling direction is set to the length of two pitches of the transport roll 18. As described above, the length of the divided cooling surface A5 in the rolling direction may be an integral multiple of the pitch of the transport roll 18.

In the following description, as shown in FIG. 8, the split cooling surface A5 whose rolling direction length is four times the pitch of the transport roll 18 will be described as an example. In this embodiment, as shown in FIG. 8, the split cooling surface A5 has a length in the rolling direction four times the pitch of the transport roll 18. However, as described above, other forms of the split cooling surface A5 can also be applied.

The cooling water nozzle 25 is a cooling water nozzle that injects cooling water vertically upward from below the steel plate transport region of the runout table toward the lower surface of the steel plate transport region, and a plurality of cooling water nozzles 25 are arranged. Various known types of nozzles can be used as the cooling water nozzle 25, and examples thereof include a pipe laminar nozzle. The cooling range of the cooling water nozzle 25 in the plate width direction is set to be equal to or less than the length of the divided cooling surface A5 in the plate width direction so that the collision range of the cooling water with the divided cooling surface A5 does not enter the other divided cooling surfaces A5. To.

FIG. 8 also shows the arrangement of the cooling water nozzle 25 with respect to the divided cooling surface A5 in the present embodiment. In FIG. 8, the cooling water nozzle 25 is represented by “●”. At least one cooling water nozzle 25 is arranged toward each of the divided cooling surfaces A5.
In the present embodiment, the cooling water nozzles 25 are arranged so that four cooling water nozzles 25 belong to one divided cooling surface A5 in a plan view of the steel plate conveying region from above. In this embodiment, the four cooling water nozzles 25 are arranged between adjacent transport rolls 18 in a plan view and are arranged in the rolling direction. The number and arrangement of the cooling water nozzles 25 belonging to one divided cooling surface A5 are not particularly limited, and may be one or a plurality.
It is easier to control if the amount of water discharged from the cooling water nozzle 25 and the flow velocity are the same for each of the cooling water nozzles 25 in the plate width direction and the rolling direction, and the cooling capacity is the same. Further, the number of cooling water nozzles 25 installed on the divided cooling surfaces A5 arranged in the plate width direction at the same position in the rolling direction, the discharge water amount, and the discharge flow velocity are the same, and the divided cooling surfaces A5 arranged in the plate width direction are the same. It is easier to control if the cooling capacity is the same.
In each of the first end-side cooling region A2 ₁ and the second end-side cooling region A2 ₂ , the cooling water nozzles 25 having the same discharge water amount and discharge flow velocity belonging to the divided cooling surfaces A5 arranged in the plate width direction are , It is preferable that the cooling water nozzles 25 adjacent to each other in the plate width direction are arranged so that the distances between the centers are all equidistant. As a result, uniform cooling in the plate width direction can be performed with higher accuracy.
Even if the cooling capacity based on the discharge water amount and the discharge flow velocity of the cooling water nozzle 25 is different in the plate width direction and the rolling direction, it is possible to control by the control device 31.

In the example of the figure, two such divided cooling surfaces A5 are arranged side by side in the rolling direction (X direction), but the number of the divided cooling surfaces A5 in the rolling direction is not limited to this example, and the total cooling area is not limited to this example. It is represented by a number obtained by dividing the rolling direction length of A1 by the rolling direction length of the divided cooling surface A5.

FIG. 8 shows the arrangement of the divided cooling surface A5 and the cooling water nozzle 25 belonging thereto in the present embodiment, but the present invention is not limited to this, and various combinations can be applied. The combinations of the divided cooling surface A5 and the cooling water nozzle 25 are exemplarily listed in FIGS. 9 to 11. Each cooling water nozzle here has the same discharge water amount and flow velocity, and the same cooling capacity is set.
In the example shown in FIG. 9, the rolling direction length of the divided cooling surface A5 is one pitch of the transport roll 18, and one cooling water nozzle 25 belongs to each divided cooling surface A5.
In the example shown in FIG. 10, the rolling direction length of the divided cooling surface A5 is one pitch of the transport roll 18, and two cooling water nozzles 25 are arranged on each divided cooling surface A5. The two cooling water nozzles 25 may be arranged in the rolling direction or in the plate width direction. Further, as shown in FIG. 10, the arrangement may be made so as to deviate from both the rolling direction and the plate width direction.
In the example shown in FIG. 11, the rolling direction length of the divided cooling surface A5 is two pitches of the transport roll 18, and four cooling water nozzles 25 are arranged on each divided cooling surface A5.

The intermediate header 26 is a header that functions as a part of the switching device in the present embodiment and supplies cooling water to the cooling water nozzle 25. In this embodiment, as can be seen from FIGS. 2 to 4, the intermediate header 26 is a tubular member extending in the rolling direction, and a plurality of cooling water nozzles 25 are provided in the rolling direction. Therefore, the injection and stop of the cooling water from the cooling water nozzle 25 arranged in one intermediate header 26 can be controlled at the same time. In the illustrated example, four cooling water nozzles 25 are arranged in the rolling direction with respect to one intermediate header 26, but the number of cooling water nozzles 25 is not limited to this.
The intermediate header 26 is arranged so as to be one on one divided cooling surface A5. As a result, it is possible to control switching between injection and stop of cooling water for each of the divided cooling surfaces A5.

In the figure, since two split cooling surfaces A5 are provided in the rolling direction, only two intermediate headers 26 are shown in the rolling direction, but the number of intermediate headers 26 in the rolling direction is the rolling direction of the split cooling surface A5. Is given by the number obtained by dividing the length of the total cooling region A1 in the rolling direction by the length of the divided cooling surface A5 in the rolling direction.

The three-way valve 28 is a member that functions as a part of the switching device in this embodiment. That is, the three-way valve 28 is a main member of the switching device for switching between collision and non-collision of the cooling water injected from the cooling water nozzle 25 with the lower surface of the steel plate transport region.
The three-way valve 28 of this embodiment is a diversion type, and is a valve that guides the water from the water supply header 29 to the pipe 27 to supply water to the intermediate header 26 and further to the cooling water nozzle 25 or to the drainage header 30. be. In this embodiment, the drainage header 30 is illustrated as a part for drainage, but the mode is not particularly limited.
Instead of the three-way valve 28 of this embodiment, two stop valves (a valve for stopping the flow of fluid in a broad sense, sometimes called an ON / OFF valve) may be installed to perform control in the same manner as the three-way valve. It is possible.

In this embodiment, one three-way valve 28 is provided in one intermediate header 26, and is arranged between a water supply header 29 for supplying cooling water and a drainage header 30 for discharging cooling water.

In the illustrated example, two water supply headers 29 and two drainage headers 30 are provided, but the number of these water supply headers 29 and drainage headers 30 is not limited to this, and for example, one is provided for each. You may.

The inside of the pipe 27 is always filled with cooling water by a three-way valve 28. As a result, when the cooling water collides with the lower surface (divided cooling surface A5) of the steel plate transport region, that is, when the lower surface of the hot-rolled steel plate 2 is cooled, the three-way valve 28 is instructed to open, and then the cooling water nozzle is used. The time (response time) from 25 to the injection of the cooling water can be shortened, and the responsiveness can be improved. The responsiveness of opening and closing the three-way valve 28 is preferably within 0.5 seconds. For example, a solenoid valve is used for the three-way valve 28.

Further, it is preferable that the three-way valve 28 is arranged at the same height as the tip of the cooling water nozzle 25. More specifically, it is preferable that the connection portion of the three-way valve 28 with the pipe 27 is located at the same height as the tip of the cooling water nozzle 25. As a result, the tip of the cooling water nozzle 25 and the tip of the pipe 27 are at the same height, and the inside of the pipe 27 is always filled with cooling water. For example, even if the seal of the three-way valve 28 is not perfect and the cooling water leaks to some extent, the inside of the pipe 27 can be filled with the cooling water, and the responsiveness can be further improved.

The three-way valve 28 is preferably provided on the side in the plate width direction with respect to the transport roll 18. For example, it is conceivable to provide the three-way valve 28 below the transport roll 18, but the space below the transport roll 18 is limited, and it is difficult to provide a plurality of three-way valves 28. It is also difficult to maintain the three-way valve 28 below the transport roll 18. In this regard, if the three-way valve 28 is provided on the side of the transport roll 18 in the plate width direction as in this embodiment, the degree of freedom in installing the three-way valve 28 is high, and maintenance can be easily performed. can.

The upstream side end detection device 32 is the position of the end portion on the plate width direction positive side (Y direction positive side) of the hot-rolled steel sheet 2 on the upstream side in the rolling direction of the _{first end side cooling region A2 1 and the second end.} Information for detecting the position of the end portion of the hot-rolled steel sheet 2 on the upstream side in the rolling direction of the side cooling region A2 _{2 on the negative side in the plate width direction (negative side in the Y direction) is acquired.} Specifically, the upstream end detection device 32 determines the position of the end face of the hot-rolled steel sheet 2 on the upstream side in the rolling direction of the _{first end cooling region A2 1 on the positive side in the plate width direction (positive side in the Y direction).} Temperature information is acquired as information for detecting the position of the end face of the hot-rolled steel sheet 2 on the upstream side in the rolling direction of the second end-side cooling region A2 _{2 on the negative side in the plate width direction (negative side in the Y direction).} ..

The upstream end detection device 32 has a thermometer 32a arranged at a position on the lower surface side of the steel sheet transport region and on the positive side in the plate width direction (positive side in the Y direction), and these thermometers 32a The acquired temperature information is used when detecting the position of the end face of the hot-rolled steel sheet 2 on the upstream side in the rolling direction of the _{first end side cooling region A2 1 on the positive side in the plate width direction (positive side in the Y direction).}
The thermometer 32a of the upstream end detection device 32 is arranged, for example, corresponding to each of the width-divided cooling zones A4 of _{the first end cooling region A2 1, and in the illustrated example, the first end cooling.} The regions A2 ₁ are provided side by side in the plate width direction so that the temperature on the upstream side of each width-divided cooling zone A4 can be measured. Since the temperature on the lower side of the region where the hot-rolled steel plate 2 passes is higher than the temperature on the lower side of the region where the hot-rolled steel plate 2 does not pass, it is acquired by the thermometer 32a arranged as described above. Based on the obtained temperature information, the position of the end face of the hot-rolled steel sheet 2 on the upstream side in the rolling direction of the _{first end-side cooling region A2 1 on the positive side in the plate width direction (positive side in the Y direction) can be detected.}

Further, the upstream end detection device 32 has a thermometer 32b arranged at a position on the lower surface side of the steel sheet transport region and on the negative side in the plate width direction (negative side in the Y direction), and the thermometer 32b. The temperature information acquired in is used when detecting the position of the end face of the hot-rolled steel sheet 2 on the upstream side in the rolling direction of the _{second end side cooling region A2 2 on the negative side in the plate width direction (negative side in the Y direction).} ..
Thermometer 32b of the upstream edge detector 32, for example, they are arranged corresponding to each of the second end side cooling region A2 ₂ width divided cooling zone A4, in the illustrated example, the second end side cooling are provided side by side in the sheet width direction so as to measure the temperature on the upstream side of the width divided cooling zone A4 region A2 _2. As a result, the position of the end face of the hot-rolled steel sheet 2 on the upstream side in the rolling direction of the second end-side cooling region A2 _{2 on the negative side in the plate width direction (negative side in the Y direction) can be detected.}

The downstream end detection device 33 is the position of the end portion of the hot-rolled steel sheet 2 on the downstream side in the rolling direction of the _{first end side cooling region A2 1 on the positive side in the plate width direction (positive side in the Y direction) and the second end.} Information for detecting the position of the end portion of the hot-rolled steel sheet 2 on the downstream side in the rolling direction of the side cooling region A2 _{2 on the negative side in the plate width direction (negative side in the Y direction) is acquired.} Specifically, the downstream end detection device 33 determines the position of the end face of the hot-rolled steel sheet 2 on the downstream side in the rolling direction of the _{first end-side cooling region A2 1 on the positive side in the plate width direction (positive side in the Y direction).} Temperature information is acquired as information for detecting the position of the end face of the hot-rolled steel sheet 2 on the negative side in the plate width direction (negative side in the Y direction) on the downstream side of the second end side cooling region A2 _{2 in the rolling direction.} ..

The downstream end detection device 33 has a thermometer 33a located on the lower surface side of the steel sheet transport region and on the positive side in the plate width direction (positive side in the Y direction), and is acquired by the thermometer 33a. The obtained temperature information is used when detecting the position of the end face of the hot-rolled steel sheet 2 on the downstream side in the rolling direction of the first end-side cooling region A2 _{1 on the positive side in the plate width direction (positive side in the Y direction).}
The thermometer 33a of the downstream end detection device 33 is arranged, for example, corresponding to each of the width-divided cooling zones A4 of _{the first end cooling region A2 1, and in the illustrated example, the first end cooling.} The regions A2 ₁ are provided side by side in the plate width direction so that the temperature on the downstream side of each width-divided cooling zone A4 can be measured. As a result, the position of the end face of the hot-rolled steel sheet 2 on the downstream side in the rolling direction of the first end-side cooling region A2 _{1 on the positive side in the plate width direction (positive side in the Y direction) can be detected.}

Further, the downstream end detection device 33 has a thermometer 33b arranged at a position on the lower surface side of the steel sheet transport region and on the negative side in the plate width direction (negative side in the Y direction), and the thermometer 33b. The information acquired in is used when detecting the position of the end face of the hot-rolled steel sheet 2 on the downstream side in the rolling direction of the _{second end side cooling region A2 2 on the negative side in the plate width direction (negative side in the Y direction).}
The thermometer 33b of the downstream end detection device 33 is arranged, for example, corresponding to each of the width-divided cooling zones A4 of _{the second end cooling region A2 2, and in the illustrated example, the second end cooling.} The regions A2 ₂ are provided side by side in the plate width direction so that the temperature on the downstream side of each width-divided cooling zone A4 can be measured. As a result, the position of the end face of the hot-rolled steel sheet 2 on the downstream side in the rolling direction of the second end-side cooling region A2 _{2 on the negative side in the plate width direction (negative side in the Y direction) can be detected.}

The control device 31 includes an electronic circuit or a computer that performs calculations based on a predetermined program, to which the upstream end detection device 32, the downstream end detection device 33, and the switching device are electrically connected. There is.
The control device 31 is the positive side (Y direction) of the hot-rolled steel sheet 2 on the upstream side in the rolling direction of the _first end side cooling region A2 1 based on the temperature information acquired by the upstream end detection device 32. The position of the end face on the positive side) and the position of the end face on the negative side in the plate width direction (negative side in the Y direction) of the hot-rolled steel sheet 2 on the upstream side in the rolling direction of the _{second end side cooling region A2 2 are detected.} Further, the control device 31 is located on the positive side in the plate width direction of the hot-rolled steel sheet 2 on the downstream side in the rolling direction of the _first end side cooling region A2 1 based on the temperature information acquired by the downstream end detection device 33. The position of the end face on the positive side in the Y direction) and the position of the end face on the negative side in the plate width direction (negative side in the Y direction) of the hot-rolled steel sheet 2 on the downstream side in the rolling direction of the _{second end side cooling region A2 2 are detected.} Then, the control device 31 controls the operation of the switching device based on the above detection result.

12 and 13 are diagrams for explaining the control performed by the control device 31. In the figure, the cooling water nozzle 25 in which the corresponding three-way valve 28 is in the closed state is represented by "●", and the cooling water nozzle 25 in which the corresponding three-way valve 28 is in the open state is represented by "○". .. The cooling water injected from the cooling water nozzle 22 to the hot-rolled steel sheet 2 is turned on and off according to the necessity of lower cooling at a predetermined rolling direction position, and is always heat in the illustrated example. Assuming that the three-way valve 28 of the cooling water nozzle 25 is always in the open state after colliding with the rolled steel plate 2, the cooling water nozzle 22 is represented by “◯” in the figure.

In the lower end cooling device 21, when the hot-rolled steel sheet 2 is conveyed to the runout table after finish rolling, the temperature is measured by the upstream end detecting device 32 and the downstream end detecting device 33. These measurement results, that is, temperature information is sent to the control device 31, and the control device 31 is based on these measurement results, as shown in FIGS. 12 and 13, the rolling direction of the _{first end-side cooling region A21.} Position U1 of the end face of the hot-rolled steel sheet 2 on the upstream side in the plate width direction (positive side in the Y direction), the negative side in the plate width direction of the hot-rolled steel plate 2 on the upstream side in the rolling direction of the _{second end side cooling region A2 2} Position U2 of the end face (negative side in the Y direction), position D1 of the end face on the positive side (positive side in the Y direction) of the hot-rolled steel sheet 2 on the downstream side in the rolling direction of the _{first end side cooling region A2 1,} The position D2 of the end face of the hot-rolled steel sheet 2 on the downstream side in the rolling direction of the end-side cooling region A2 _{2 on the negative side in the plate width direction (negative side in the Y direction) is detected.}
Next, the control device 31 determines the end surface 2a of the hot-rolled steel sheet 2 on the positive side in the plate width direction (positive side in the Y direction) in _{the first end-side cooling region A2 1} based on the above positions U1, U2, D1, and D2. The position and the position of the end face 2b on the negative side in the plate width direction (negative side in the Y direction) of the hot-rolled steel sheet ₂ in the second end side cooling region A2 2 are calculated. In the control device 31, the above calculation is performed on the assumption that the hot-rolled steel sheet 2 exists linearly between the upstream end detection device 32 and the downstream end detection device 33.

Then, the control device 31 controls the opening and closing of the three-way valve 28 for each of the divided cooling surfaces A5 based on the calculation result.
Specifically, the control device 31 has a divided cooling surface A5 in which the detected end surface 2a of the hot-rolled steel plate exists on the cooling surface A5 among the divided cooling surfaces A5 of _{the first end side cooling region A2 1.} The three-way valve 28 is controlled to be closed with respect to the divided cooling surface A5 outside the existing divided cooling surface A5 and in the vicinity of the cooling surface A5. Further, the control device 31 controls the cooling surface A5 inside the divided cooling surface A5 in the vicinity so that the three-way valve 28 is in the open state. Furthermore, the control device 31 of the second end side cooling region A2 ₂ divided cooling surface A5, and the divided cooling surface A5 of the end face 2b of the detected hot-rolled steel sheet is present on the cooling surface A5, the presence The three-way valve 28 is controlled so as to be closed on the outer side of the divided cooling surface A5 and the divided cooling surface A5 around the cooling surface A5. Further, the control device 31 controls the cooling surface A5 inside the peripheral divided cooling surface A5 so that the three-way valve 28 is in an open state.

By controlling in this way, even when the hot-rolled steel sheet 2 is not meandering as shown in FIG. 12 or when the hot-rolled steel sheet 2 is meandering as shown in FIG. 13, the hot-rolled steel sheet 2 is a plate. Since both ends in the width direction are masked symmetrically and the cooling water does not collide with the both ends, it is possible to prevent the both ends from being overcooled.

Further, when the cooling device disclosed in Patent Document 1 is used in order to prevent the cooling water from colliding with both ends of the hot-rolled steel sheet, it is necessary to move the masking unit, so that the response speed for switching between collision and non-collision Is slow. The same applies when the cooling device disclosed in Patent Documents 2 and 3 is used. Since the transport speed of the hot-rolled steel sheet is very fast, from several m / s to more than 20 m / s, if the response speed of the above switching is slow, the hot-rolled steel sheet is, for example, several tens of m during the response time. It will be transported.
On the other hand, in the lower width direction control cooling device 17, the three-way valve 28 is provided in the intermediate header 26, and the three-way valve 28 is arranged at the same height as the tip of the cooling water nozzle 25, so that the inside of the pipe 27 is provided. Can always be filled with cooling water. Therefore, when the opening and closing of the three-way valve 28 is controlled based on the measurement results of the upstream side end detection device 32 and the downstream side end detection device 33 and the cooling water injected from the cooling water nozzle 25 is controlled, the responsiveness thereof is obtained. Can be made extremely good.

In order to more reliably fill the inside of the pipe 27 with the cooling water, the cooling water may be constantly discharged from the cooling water nozzle 25. That is, for the intermediate header 26 that does not cause the cooling water from the cooling water nozzle 25 to collide with the divided cooling surface A5, the cooling water from the cooling water nozzle 25 continues to be discharged to the extent that it does not collide with the divided cooling surface A5. The opening degree of the valve 28 is controlled. On the other hand, with respect to the intermediate header 26 that causes the cooling water from the cooling water nozzle 25 to collide with the divided cooling surface A5, the three-way valve 28 is opened so that the cooling water from the cooling water nozzle 25 collides with the divided cooling surface A5. Control the degree. In such a case, the inside of the pipe 27 is surely filled with the cooling water, so that the responsiveness can be ensured.

In the lower width direction control cooling device 17 of the above embodiment, the configuration of the thermometers 32a, 32b, 33a, 33b is not particularly limited as long as it measures the temperature of the hot-rolled steel sheet 2, but for example. It is preferable to use the thermometer described in Japanese Patent No. 3818501 and the like.

The thermometer described in the above publication or the like has a radiation thermometer that measures the temperature of the hot-rolled steel sheet 2 and a radiation thermometer whose tip is arranged at a position facing the steel plate transport region (hot-rolled steel sheet 2) and whose rear end is a radiation thermometer. A nozzle as a water column forming portion that injects water toward the lower surface of the steel plate transport region in order to form a water column between the optical fiber connected to the steel plate transport region and the tip of the optical fiber, and water in the nozzle. It has a water tank for supplying water. This thermometer measures the lower surface temperature of the hot-rolled steel sheet 2 by receiving synchrotron radiation from the lower surface (hot-rolled steel sheet 2) of the steel plate transport region via the water column with a radiation thermometer. By using this thermometer, it is possible to reduce the measurement error caused by the cooling water from the cooling water nozzle 25.

The intermediate header 26 is provided with a three-way valve 28, and the smaller the number of cooling water nozzles 25 in the intermediate header 26, the better the controllability of the cooling water injected onto the hot-rolled steel sheet 2. On the other hand, if the number of the cooling water nozzles 25 is reduced, the number of required three-way valves 28 is increased by that amount, and the equipment cost and the running cost are increased. Therefore, the number of cooling water nozzles 25 can be set in consideration of these balances.

When a small amount of cooling water is used to collide the cooling water with the divided cooling surface A5, the length of the total cooling region A1 in the rolling direction becomes long. Therefore, for example, it is preferable to inject cooling water having a large water density of ^{1 m 3} / m ^{2 / min or more from the cooling water nozzle 25.}

In the above-mentioned form, the intermediate header 26 is provided, but the form is not limited to the intermediate header 26, and a form having no intermediate header 26 is also possible. FIG. 14 is a plan view showing an outline of the configuration of the lower width direction control cooling device 17 according to this embodiment. FIG. 14 is a diagram corresponding to FIG. 4, and a three-way valve 28 is connected to each cooling water nozzle 25. However, in order to facilitate understanding, FIG. 14 shows the three-way valve 28 and the water supply header 29. , And the description of the drainage header 30 is omitted.

In the form shown in FIG. 14, a pipe (not shown) is connected to each cooling water nozzle 25, and a three-way valve is provided in this pipe. The three-way valve is provided between the water supply header that supplies the cooling water to the pipe and the drainage header that discharges the cooling water. Even in such a form in which one three-way valve is provided for one cooling water nozzle 25, it is possible to obtain the same effect as the effect obtained in the above form. Even in this case, the concept of the divided cooling surface A5 is the same as that of the lower width direction control cooling device 17 described above.

Although the lower width direction control cooling device 17 in the example shown in FIG. 1 is arranged on the upstream side of the lower width direction control cooling device 16, the arrangement location of the lower width direction control cooling device 17 is not limited to this example.

If the lower width direction control cooling device 17 is arranged on the upstream side of the lower cooling device 16 as in the example shown in FIG. 1, the non-uniform temperature distribution that occurs in the hot-rolled steel sheet 2 due to the meandering of the hot-rolled steel sheet 2. Can be removed early in the cooling process.

In the above description, the positions of the end faces 2a and 2b of the hot-rolled steel sheet 2 in the plate width direction are detected / calculated based on the temperature information, but the method of detecting / calculating the positions is not limited to this method. For example, the upstream side and downstream side end detection devices 32 and 33 may be configured by an image imaging device, and the positions of the end faces 2a and 2b of the hot-rolled steel sheet 2 in the plate width direction may be detected / calculated based on the imaging information. .. When the upstream side and downstream side end detection devices 32 and 33 are configured by the image imaging device, the devices 32 and 33 may be provided on the upper side of the steel plate transport region. Further, when the upstream side and downstream side end detection devices 32 and 33 are configured by the image imaging device, the regions to be imaged by the upstream side and downstream side end detection devices 32 and 33 are the first end side cooling regions A2 _1. It may be an upstream side or a downstream side region of the second end side cooling region A2 ₂ , or it may be a first end side cooling region A2 ₁ or a second end side cooling region A2 ₂ .

Further, in the above description, a mode in which a control device is used to control the number of switching devices that operate so as to cause the cooling water to collide with the divided cooling surface has been illustrated. The present invention is not limited to this mode, and for example, in addition to controlling the number of switching devices, it is also possible to control the flow rate of the cooling water injected from the cooling water nozzle. The flow rate of the cooling water can be controlled by using a flow rate adjusting valve. In this case, the flow control valve can be provided between the intermediate header and the switching device.

Although the embodiments of the present invention have been described above, the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the technical idea described in the claims, and of course, the technical scope of the present invention also includes them. It is understood that it belongs to.

Hereinafter, the effects of the present invention will be described based on Examples and Comparative Examples. However, the present invention is not limited to this embodiment.

<Example 1>
In the verification of the effect, the lower width direction control cooling device 17 shown in FIG. 2 was used as the cooling device of the first embodiment. Further, as the cooling device of Comparative Example 1, the conventional lower cooling device 16 was applied without using the lower width direction control cooling device 17.

The conditions in this verification are as follows. The operating conditions of Example 1 were a steel plate width: 1300 mm, a plate thickness: 3.2 mm, a steel plate transport speed: 600 mpm, a temperature before cooling: 900 ° C., and a target take-up temperature: 550 ° C. In the lower width direction control cooling device 17 of FIG. 4, there are two intermediate headers in the rolling direction, and four cooling water nozzles are arranged in each intermediate header. However, in the first embodiment, four are arranged in the rolling direction. There were two intermediate headers, and two cooling water nozzles were installed in each intermediate header. The cooling length in the rolling direction was 75 places between the transport rolls, and the response speed including the three-way valve and the piping system was 0.2 seconds. The density of the cooling water to be injected was set to 2 m ³ / m ² / min. The installation position of the lower width direction control cooling device was set to the side closer to the finishing rolling mill (upstream side of the lower cooling device 16).
On the other hand, the operating conditions of Comparative Example 1 were that there was no cooling control function in the plate width direction and the density of the injected cooling water was 0.7 m ³ / m ² / min.

FIG. 15 shows an example in which a part of the temperature distribution on the upper surface of the steel sheet in Comparative Example 1 was taken out. In FIG. 15, in order to make the temperature distribution display easier to understand, only the distribution on the lower temperature side than the target temperature is displayed in shades (the same applies to FIG. 16 shown later). The shaded area is the area below −30 ° C. with respect to the target temperature. As can be seen from FIG. 15, in Comparative Example 1, relatively wide low temperature portions p of 100 mm or more were generated at both ends in the plate width direction.
According to Comparative Example 1, the standard temperature deviation was 23.9 ° C. The standard temperature deviation was obtained from the results measured by the infrared temperature image measuring device from all the measurement points of the steel plate temperature excluding the tip and the tail end of the steel sheet of 10 m each and the both ends of each of 50 mm.

FIG. 16 shows an example in which a part of the temperature distribution on the upper surface of the steel sheet in Example 1 was taken out. As can be seen from FIG. 16, in Example 1, the low temperature portion is 30 mm or less, and it can be seen that it hardly occurs.
Therefore, according to the present invention, it was found that the temperature in the plate width direction of the hot-rolled steel sheet can be made uniform.

The present invention is useful for cooling techniques for hot-rolled steel sheets.

1 Slab 2 Hot-rolled steel plate 10 Hot-rolled equipment 11 Heating furnace 12 Width rolling machine 13 Rough rolling mill 14 Finishing rolling mill 15 Upper cooling device 16 Lower cooling device 17 Lower width direction control cooling device 18 Conveyance roll 19 Winding Device 20 Lower central cooling device 21 Lower end cooling device 22 Cooling water nozzle 23 Header 24 Piping 25 Cooling water nozzle 26 Intermediate header 27 Piping 28 Three-way valve 29 Water supply header 30 Drainage header 31 Control device 32 Upstream end detection Device 33 Downstream end detection device 32a, 32b, 33a, 33b Thermometer

Claims (7)

A cooling device that cools the lower surface of a hot-rolled steel sheet that is transported on a transport roll to a winding device after finish rolling in the hot rolling process.
The entire region of the lower surface of the steel plate transport region in the plate width direction and the cooling region defined by the predetermined length in the rolling direction are defined as the total cooling region, and one of the regions at both ends in the plate width direction of the total cooling region is the first. Each cooling obtained by dividing each of the first end-side cooling region and the second end-side cooling region into a plurality of parts in the plate width direction, with the end-side cooling region and the other as the second end-side cooling region. The width division cooling zone, which is the area, and
A divided cooling surface, which is a cooling region obtained by dividing the width-divided cooling zone into a plurality of parts in the rolling direction,
At least one cooling water nozzle that injects cooling water onto the lower surface of each of the divided cooling surfaces,
A switching device that switches between collision and non-collision of the cooling water ejected from the cooling water nozzle with the divided cooling surface.
An end detection device for acquiring information for detecting the position of an end portion of the hot-rolled steel sheet in the plate width direction, and an end detection device.
A control device that detects the position of the end portion in the plate width direction based on the information and controls the operation of the switching device based on the detection result.
Is provided ,
The switching device
The flow of the cooling water is passed between the water supply header for supplying the cooling water and the drainage header or the drainage area for draining the cooling water, which are provided in the pipe through which the cooling water supplied to the cooling water nozzle flows. Equipped with a three-way valve to switch,
The three-way valve, the transport roll is provided in an the side of the plate width direction, the disposed at the same height as the tip of the cooling water nozzles, characterized that you have, the cooling apparatus of hot rolled steel sheet. The cooling water nozzle for a hot-rolled steel sheet according to claim 1, wherein one or more cooling water nozzles corresponding to each of the divided cooling surfaces are arranged in the cooling water nozzle. The cooling device for a hot-rolled steel sheet according to claim 1 or 2, wherein the lengths in the rolling direction of each of the divided cooling surfaces included in the width-divided cooling zone are the same in the rolling direction. The cooling device for a hot-rolled steel sheet according to any one of claims 1 to 3, wherein the length of the divided cooling surface in the rolling direction is a multiple of the length between the transport rolls. In each of the first end-side cooling region and the second end-side cooling region, the arrangement of the plurality of the cooling water nozzles in the plate width direction is such that the distance between the centers of the cooling water nozzles adjacent to each other in the plate width direction is large. The cooling device for a hot-rolled steel sheet according to any one of claims 1 to 4, wherein all of them are arranged so as to be equidistant. The cooling device for a hot-rolled steel sheet according to any one of claims 1 to 5 , wherein the end detection device is provided on both the upstream side in the rolling direction and the downstream side in the rolling direction of the cooling region. A cooling method that cools the lower surface of a hot-rolled steel sheet that is transported on a transport roll to a winding device after finish rolling in the hot rolling process.
The entire area of the lower surface of the steel plate transport region in the plate width direction and the cooling region defined by the predetermined length in the rolling direction are defined as the total cooling region, and one of the regions at both ends in the plate width direction of the total cooling region is the first. Each cooling obtained by dividing each of the first end-side cooling region and the second end-side cooling region into a plurality of parts in the plate width direction, with the end-side cooling region and the other as the second end-side cooling region. The region is a width-divided cooling zone, and the cooling region obtained by dividing the width-divided cooling zone into a plurality of parts in the rolling direction is a divided cooling surface.
The position of the end portion of the hot-rolled steel sheet in the plate width direction is detected.
Based on the detection result, collision and non-collision of the cooling water with the hot-rolled steel plate by the cooling water nozzle is provided for each of the divided cooling surfaces in the pipe through which the cooling water supplied to the cooling water nozzle flows. A three-way valve that switches the flow of the cooling water between a water supply header that supplies cooling water and a drainage header or drainage area that drains the cooling water, and is provided on the side of the transport roll in the plate width direction. A method for cooling a hot-rolled steel plate, which is controlled by a switching device provided with a three-way valve arranged at the same height as the tip of the cooling water nozzle.

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