JP4544235B2 - Apparatus and method for cooling hot-rolled steel strip - Google Patents

Description

  The present invention relates to a cooling device and a cooling method for cooling a hot-rolled steel strip.

  In general, in order to manufacture a hot-rolled steel strip, a slab is heated to a predetermined temperature in a heating furnace, and the heated slab is rolled to a predetermined thickness with a roughing mill to form a rough bar. In a continuous hot finishing rolling mill comprising a rolling stand, a steel strip having a predetermined thickness is formed. And after cooling this steel strip with the cooling device on a run-out table, it manufactures by winding up with a winder.

  At that time, in the run-out table cooling device that continuously cools the hot-rolled hot steel strip, in order to cool the upper surface of the steel strip, a circular laminar cooling nozzle is placed on the roller table for transporting the steel strip. A plurality of laminar cooling water is poured in a straight line over the width direction. On the other hand, in order to cool the lower surface of the steel strip, a spray nozzle is provided between the roller tables, and a method of injecting cooling water therefrom is generally used.

  However, in such a conventional cooling device, since the cooling water from the circular tube laminar nozzle used for cooling the upper surface of the steel strip is a free fall flow, there is a water film of retained water on the upper surface of the steel strip. The cooling water is difficult to reach the steel strip, and there is a problem that the cooling capacity varies depending on whether there is stagnant water on the upper surface of the steel strip, or the cooling water that falls on the steel strip spreads freely in the front, back, left, and right. There is a problem that the cooling region (cooling zone) changes and the cooling capacity is not stable. As a result of such fluctuations in cooling capacity, the material of the steel strip tends to be uneven.

  Therefore, in order to drain the cooling water (residual water) on the upper surface of the steel strip and obtain a stable cooling capacity, a method of discharging the accumulated water by ejecting the fluid in an oblique direction across the upper surface of the steel strip (for example, , Patent Document 1), and a method of making the cooling region constant by blocking the stagnant water by using a constraining roll for constraining the vertical movement of the steel strip as a draining roll (for example, see Patent Document 2) has been proposed. Yes.

In the [Best Mode for Carrying Out the Invention] column, the following Patent Document 3 is cited, which is also described here.
JP-A-9-141322 JP-A-10-166023 JP 2002-239623 A

  However, according to the method described in Patent Document 1, since a large amount of cooling water stays on the upper surface of the steel strip as it goes downstream, the draining effect becomes less effective toward the downstream side. Moreover, in the method of patent document 2, since the steel strip front-end | tip part from a rolling mill to a winding machine is conveyed in the state which is not restrained by a restraint roll, by a restraint roll (draining roll) The draining effect cannot be obtained. Moreover, since the steel strip tip passes over the run-out table in a state where it swells while moving up and down, if cooling water is supplied to the top surface of this steel strip tip, the bottom of the bottom where waves are struck Cooling water tends to stay selectively, and the hunting phenomenon of the cooling temperature does not occur until the steel strip tip is taken up by a winder and tension is applied to the steel strip, and the steel strip is stretched and the vertical wave is eliminated. Arise. This cooling temperature hunting phenomenon also caused variations in the mechanical properties of the steel strip.

  The present invention has been made in consideration of the above-mentioned circumstances, and its object is to realize a high cooling capacity and a stable cooling region when cooling a hot-rolled steel strip with cooling water. Thus, an object of the present invention is to provide a cooling device and a cooling method for a hot-rolled steel strip that can uniformly cool the steel strip from the front end to the tail end.

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

[1] A cooling device for a hot-rolled steel strip for cooling a hot-rolled steel strip after finish rolling conveyed on a run-out table,
On the upper surface side of the steel strip, a plurality of cooling nozzles that inject the rod-shaped cooling water so that the injection angle is inclined toward the upstream side in the traveling direction of the steel strip, and
A cooling device for a hot-rolled steel strip, wherein a draining means for draining the cooling water on the upper surface of the steel strip injected from the cooling nozzle is arranged on the upstream side.

[2] A plurality of the cooling nozzles are arranged in the steel strip width direction and a plurality of rows are arranged in the steel strip traveling direction.
Further, the width direction positions of the cooling nozzles arranged in each row are arranged by shifting the width direction position in the upstream row and the width direction position in the downstream row [1] The cooling apparatus for hot-rolled steel strips described in 1.

  [3] The cooling apparatus for a hot-rolled steel strip according to [1] or [2], wherein an angle formed between the rod-shaped cooling water sprayed by the cooling nozzle and the steel strip is 55 ° or less.

  [4] The hot-rolled steel according to [2] or [3], wherein the cooling nozzle row is capable of independently controlling on / off of cooling water using one or more rows as control units. Belt cooling system.

  [5] The hot-rolled steel strip according to any one of [1] to [4], wherein the draining means is a rotationally driven pinch roll that can be moved up and down so as to roll on the steel strip. Cooling system.

  [6] The draining means is one or more nozzles that eject the draining fluid from slit-shaped or circular nozzle ejection ports so that the ejection angle is inclined toward the downstream side in the traveling direction of the steel strip. The apparatus for cooling a hot-rolled steel strip according to any one of the above [1] to [4].

[7] A method for cooling a hot-rolled steel strip after finish rolling conveyed on a run-out table,
While inclining toward the upper surface side of the steel strip toward the upstream side in the direction of travel of the steel strip and injecting rod-shaped cooling water,
A method for cooling a hot-rolled steel strip, characterized in that cooling water is drained by a draining means provided on the upstream side.

  [8] The hot-rolled steel according to [7], wherein the cooling capacity is controlled by changing the cooling zone length by controlling the number of nozzle rows in the traveling direction of the steel strip through which the rod-shaped cooling water is injected. How to cool the belt.

[9] A pinch roll is used for the draining means, and the pinch roll is preliminarily set with a gap equal to or less than the thickness of the steel strip, and starts to inject cooling water after the steel strip tip is pinched,
The method of cooling a hot-rolled steel strip according to the above [7] or [8], wherein the pinch roll is slightly raised while rotating the tip of the steel strip almost simultaneously with the coiler.

  [10] Using a nozzle for injecting a draining fluid from a slit-shaped or circular nozzle injection port inclined toward the downstream side in the traveling direction of the steel strip in the draining means, and tilting toward the upstream side in the traveling direction of the steel strip And changing one or more of the amount of water in the nozzle for injecting the draining fluid, the water pressure, and the number of rows of spray nozzles according to the number of rows of rod-shaped coolant jet nozzles to be sprayed. The method for cooling a hot-rolled steel strip according to [8].

  [11] Control of the number of nozzle rows in the steel strip traveling direction that inclines toward the upstream side in the traveling direction of the steel strip and injects rod-shaped cooling water is performed by preferentially injecting the nozzle row on the draining means side and downstream The method of cooling a hot-rolled steel strip according to any one of [8] to [10], wherein the cooling zone length is changed by sequentially turning on and off the nozzle array on the side.

  According to the present invention, cooling can be performed uniformly from the front end to the tail end of the steel strip, and the quality of the steel strip is stabilized. Along with this, the cutting margin of the steel strip is reduced and the yield is increased.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a hot-rolled steel strip manufacturing facility in the first embodiment of the present invention.

  The coarse bar 2 rolled by the coarse rolling mill 1 is conveyed on the table roller 3 and continuously rolled to a predetermined thickness by seven continuous finish rolling mill groups 4 to form a steel strip 12, and then the final finish. It is led to the run-out table 5 constituting the steel strip conveyance path behind the rolling mill 4E. The runout table 5 has a total length of about 100 m, and a cooling device is provided in a part or most of the runout table 5. After the steel strip 12 is cooled here, the runout table 5 is wound by a downstream winder 13 and heated. It becomes an extension coil.

  And in this embodiment, the conventional cooling device 6 and the cooling device 10 of this invention are arrange | positioned in that order as a cooling device for steel strip upper surface cooling provided in the run-out table 5. FIG. The conventional cooling device 6 includes a plurality of circular laminar nozzles 7 arranged at a predetermined pitch on the upper surface side of the run-out table 5 and supplying cooling water to the steel strip as a free fall flow. Moreover, as a cooling device for cooling the steel strip lower surface, a plurality of spray nozzles 9 are arranged between the table rollers 8 for transporting the steel strip.

  Here, the configuration around the cooling device 10 according to the first embodiment of the present invention is as shown in FIG. A cooler body 10a described later is provided on the upper surface side of the run-out table 5, and a pinch roll 11 as a draining means is provided on the upstream side thereof. The structure on the lower surface side of the steel strip is the same as that of the conventional cooling device 6. For example, a rotating steel strip conveying table roller 8 having a diameter of about 350 mm and a pitch of about 400 mm is disposed in the traveling direction of the steel strip. These table rollers 8 are located on the lower surface side of the steel strip 12.

  The configuration of the cooling device main body 10a is as shown in FIG. That is, the circular pipe nozzles 15 arranged in a row at a predetermined pitch (for example, 30 mm pitch) in the steel strip width direction on the cooling water nozzle header 14 are predetermined at a predetermined pitch (for example, 100 mm pitch) in the steel strip traveling direction. The number of columns (for example, 100 columns) is provided. The circular pipe nozzle 15 is connected to the cooling water supply pipe 16 via one cooling water nozzle header 14 for each row, and each cooling water supply pipe 16 can be controlled on and off independently. ing.

  The circular tube nozzle 15 is a straight tube nozzle having a predetermined inner diameter (for example, 10 mmφ) and a smooth inner surface, and the cooling water supplied from the circular tube nozzle 15 is a rod-shaped cooling water. And this circular pipe nozzle 15 is inclined and arrange | positioned so that rod-shaped cooling water may be injected toward the upstream of the advancing direction of the steel strip 12 with predetermined | prescribed injection angle (theta) (for example, (theta) = 50 degrees). The height of the outlet of the circular tube nozzle 15 is set a predetermined height (for example, 1000 mm) away from the upper surface of the steel strip 12 so that it does not contact the circular tube nozzle 15 even if the steel strip 12 moves up and down. ing.

  Here, the rod-shaped cooling water in the present invention is cooling water injected in a state of being pressurized to some extent from a circular (including elliptical or polygonal) nozzle outlet, and is cooled from the nozzle outlet. The water jet velocity is 7 m / s or more, and the water flow has a continuous and straight running cooling water in which the cross section of the water flow from the nozzle outlet to the steel strip is maintained in a substantially circular shape. That is, it is different from a free fall flow from a circular tube laminar nozzle or a liquid ejected in a droplet state such as a spray.

  On the other hand, the pinch roll 11 which is a draining means is installed on the table roll 8 on the upstream side of the cooling apparatus main body 10a, and is a roll having a predetermined size (for example, a diameter of 250 mm), The steel strip 12 is sandwiched between them. And the pinch roll 11 is rotationally driven and can be moved up and down so as to make rolling contact with the steel strip 12, and the holding of the height position can be arbitrarily changed. The interval (gap) between the pinch roll 11 and the table roller 8 is set in advance to be smaller than the plate thickness of the steel strip 12 (for example, plate thickness -1 mm), and the tip of the steel strip 12 coming out from the finish rolling mill is the pinch roll. 11, after reaching the outlet side of the cooling device main body 10 a, the injection of the cooling water is started from the circular tube nozzle 15. Further, a drive motor (not shown) for rotationally driving the pinch roll 11 is connected to the side portion of the pinch roll 11, and the pinch roll 11 matches the conveying speed of the steel strip 12 by this drive motor. The rotation speed is adjusted to be the peripheral speed. In addition, the cooling device main body 10a and the pinch roll 11 are located at the position where the cooling water sprayed from the circular tube nozzle arranged in the foremost row (row on the most upstream side) reaches the steel strip 12, and the pinch roll 11 is made of steel. It is adjusted so as to be on the downstream side of the position where it contacts the belt 12.

  As described above, in this embodiment, the cooling device 10 has a plurality of circular tube nozzles arranged so as to be inclined so as to inject the rod-shaped cooling water toward the upstream side in the traveling direction of the steel strip 12 at the injection angle θ. 15 and the pinch roll 11 which is disposed on the upstream side and sandwiches the steel strip 12 between the roller table 8 and the cooling water supplied from the circular tube nozzle 15 to the upper surface of the steel strip 12 (Stagnant water) flows toward the upstream side of the steel strip 12 in the traveling direction, and the flowing staying water is blocked by the pinch roll 11, so that the cooling region by the cooling water becomes constant. And since rod-shaped cooling water is injected from the circular tube nozzle 15, the water film of the staying water on the steel strip 12 upper surface can be broken, and fresh cooling water can be made to reach the steel strip 12.

  Also, in the past, the tip of the steel strip was shaped like a wave, and cooling water was selectively retained at the bottom of the wave that waved up and down, resulting in supercooling. The stagnant water will not flow out (upstream).

  As a result, there is a problem that there is a difference in cooling capacity between the case where there is stagnant water on the upper surface of the steel strip and the case where it falls on the steel strip, as in the conventional cooling device using free fall flow from the circular tube laminar nozzle. The problem that the cooling water spreads freely in the front, rear, left and right to change the cooling region and the cooling capacity is not stable is solved, and a high and stable cooling capacity can be obtained regardless of the steel strip shape. For example, rapid cooling exceeding a cooling rate of 100 ° C./s is possible for a steel strip having a thickness of 3 mm.

  In the above, it is preferable that the angle θ between the rod-shaped cooling water sprayed from the circular tube nozzle 15 and the steel strip 12 is 55 ° or less. When the steel strip is stationary, when the angle θ exceeds 60 °, the velocity component in the traveling direction of the cooling water (residual water) after reaching the steel strip 12 decreases, and the upstream row stays there. Interfering with the water, the flow of stagnant water is hindered, whereby a part of the stagnant water flows out downstream from the arrival position (collision position) of the rod-shaped cooling water from the circular tube nozzle 15 on the most downstream side. There is a risk that the cooling area will not be stable. Furthermore, with the progress of the steel strip, the faster the traveling speed, the easier the stagnant water flows out to the downstream side. Therefore, in order to ensure that the cooling water after reaching the steel strip 12 flows to the upstream side of the steel strip traveling direction, the angle θ is preferably set to 55 ° or less, depending on the traveling speed of the steel strip. It is more preferable to adjust in the range of ° to 55 °. However, when the angle θ is smaller than 30 °, if the height position from the steel strip 12 is maintained at a predetermined value, the distance from the circular nozzle 15 to the arrival position (collision position) of the rod-shaped cooling water is as follows. Since the rod-shaped cooling water is dispersed too far and there is a risk that the cooling characteristics may deteriorate, the angle θ formed by the rod-shaped cooling water and the steel strip 12 is preferably 30 ° or more.

  Incidentally, in the present invention, the circular pipe nozzle 15 that forms rod-shaped cooling water is adopted as the cooling water nozzle for the following reason. That is, in order to perform cooling reliably, it is necessary to make the cooling water reliably reach the steel strip and collide with it. For this purpose, the water film on the upper surface of the steel strip 12 must be broken to allow fresh cooling water to reach the steel strip 12, and cooling with a weak penetrating force such as a group of droplets ejected from the spray nozzle. It should be a cooling water flow with high penetration that is continuous and straight, not a water flow. Furthermore, since the laminar flow by the circular tube laminar nozzle that has been used in the past is a free-falling flow, if there is a stagnant water film, it is difficult for the cooling water to reach the steel strip, and when there is no stagnant water. There are problems such as a difference in cooling capacity, and a change in cooling capacity when the speed of the steel strip changes because the water that has fallen on the steel strip spreads back and forth and right and left. Therefore, in the present invention, the circular pipe nozzle 15 (which may be an ellipse or a polygon) may be used, the cooling water injection speed from the nozzle outlet is 7 m / s or more, and the steel outlet from the nozzle outlet The rod-shaped cooling water is jetted with continuity and straightness that keeps the cross section of the water flow until it collides. According to the rod-shaped cooling water having a cooling water injection speed of 7 m / s or more from the nozzle outlet, the water film on the upper surface of the steel strip is stably formed even when the cooling water is inclined and injected. Because it can break through. Moreover, in the present invention, since the cooling water is jetted from the diagonally upward direction in reverse to the steel strip in the traveling direction of the steel strip, the steel strip and the cooling water when the cooling water collides with the steel strip. The relative speed is higher than the case where the speed of the steel strip in the direction opposite to the steel strip (fluid speed x cosθ) is added and the relative speed is perpendicularly collided. For example, the water flow does not disperse and breaks up the staying water existing on the steel strip to reach the steel strip, thereby enabling stable cooling.

  Although it is conceivable to use a slit-shaped nozzle instead of the circular tube nozzle 15, if a slit-shaped nozzle having a gap (practically 3 mm or more) that does not clog the nozzle is used, Compared with the case where 15 is installed at intervals in the width direction, the nozzle cross-sectional area becomes extremely large. For this reason, in order to inject cooling water at an injection speed of 7 m / s or more from the nozzle outlet in order to have a penetrating force to the staying water film, an extremely large amount of water is required, and the equipment cost is enormous and difficult to realize. It is.

  In addition, the method of injecting the cooling water from the diagonally upward direction by reversing the cooling water with respect to the steel strip in the traveling direction of the steel strip is more effective than the conventional cooling method in which the cooling water is dropped perpendicularly to the steel strip. Cooling efficiency is good because the relative speed is large. In addition, the cooling efficiency is excellent because the relative speed between the cooling water and the steel strip is large compared to the case of injecting the cooling water from the rear in the steel strip traveling direction.

  The thickness of the rod-shaped cooling water is preferably about several mm and at least 3 mm. This is because if it is less than 3 mm, it is difficult to break through the accumulated water on the steel strip and cause the cooling water to collide with the steel strip.

  Further, regarding the arrangement of the circular pipe nozzles 15, as shown in FIG. 7, the collision position of the rod-shaped cooling water in the previous row (upstream side) and the collision position of the rod-shaped cooling water in the next row (downstream side) are shifted in the width direction. Are preferably arranged. As an example of the shifting method, as shown in FIG. 8, for example, as shown in FIG. 8A, the nozzles in the next row have the same mounting pitch in the width direction as in the previous row, and the width direction mounting position is 1 in the width direction nozzle mounting pitch. The distance may be shifted by / 3, or as shown in (b), in the next row, it may be installed at the center of adjacent nozzles in the previous row. As a result, the rod-shaped cooling water in the next row collides with a portion where the cooling becomes weak between the rod-shaped cooling waters adjacent in the width direction, and the cooling is supplemented to achieve uniform cooling in the width direction.

  In addition, as mentioned above, in this cooling device 10, the space | interval of the pinch roll 11 and the roller table 8 is previously set smaller than the plate | board thickness of the steel strip 12 (for example, plate | board thickness -1mm), from a finishing mill When the tip of the steel strip 12 that has come out passes through the pinch roll 11 and reaches the outlet side of the cooling device main body 10a, the injection of the cooling water is started from the circular tube nozzle 15, but the plate thickness is thick (for example, (Sheet thickness 2 mm or more) In the steel strip, the tip of the steel strip may be passed through the location where the cooling water has been previously jetted. If it carries out like this, predetermined cooling will be attained from the front-end | tip of the steel strip 12. FIG. In addition, when the steel strip 12 is thin and the passage of the steel strip 12 becomes unstable due to the influence of the cooling water, the cooling water is supplied at an injection pressure that does not hinder the passage of the tip of the steel strip 12. It is possible to change the injection pressure to a predetermined injection pressure after the steel strip has been injected and the tip of the steel strip has bitten into the pinch roll 11. However, since the vertical movement of the steel strip 12 generated between the finish rolling mill 4 and the pinch roll 11 is suppressed by the pinch roll 11, the plate at the tip of the steel strip passing through the cooling device main body 10a is the pinch roll. 11 is relatively stable as compared with the case without 11 and there is little trouble even if the cooling water is started to be injected before the tip of the steel strip 12 reaches the outlet side of the cooling device main body 10a. Therefore, it is preferable to adjust so as to start the injection of the cooling water at a timing that does not interfere with the sheet passing according to the plate thickness, the conveyance speed, the steel strip temperature, and the like. And if the front-end | tip of the steel strip 12 is wound up by the winder 13, and tension | tensile_strength is applied, with the pinch roll 11 rotating slightly so that it may become a gap more than the plate | board thickness of the steel strip 12 (for example, plate | board thickness) Raise to + 1mm. Even in this state, the cooling water on the steel strip 12 hardly passes through to the upstream side of the pinch roll 11, and good water draining is realized by the pinch roll 11. Incidentally, the reason why the pinch roll 11 is slightly raised is to prevent the steel strip from being scratched or loosened due to a slight mismatch between the pinch roll rotation speed and the steel strip traveling speed.

  And based on the advancing speed, temperature, etc. of the steel strip 12, the injection of cooling water is adjusted as follows. First, based on the traveling speed of the steel strip 12, the measured temperature value of the steel strip 12, and the cooling temperature amount up to the target cooling stop temperature, the length of the cooling zone, that is, the row of the circular tube nozzles 15 for injecting rod-shaped cooling water. Find a number. And it sets so that it may inject preferentially from the side close | similar to the pinch roll 11 by the row | line number of the calculated | required circular tube nozzle 15. FIG. Thereafter, the number of rows of the circular tube nozzles 15 to be injected is changed while taking into account the change (acceleration / deceleration) of the traveling speed of the steel strip 12 by looking at the actual temperature value of the steel strip 12 after cooling. The change of the cooling zone length is preferably performed by always ejecting the nozzle rows on the pinch roll 11 side, and changing the number of rows to be ejected by sequentially turning on and off the downstream nozzle rows.

  In addition, the main role of this pinch roll 11 is that the cooling area | region by a cooling water becomes fixed by blocking the cooling water from the cooling device main body 10a. Therefore, as will be described later in the second embodiment of the present invention, the draining means is not limited to the pinch roll 11 as described above, but drains the cooling water on the upper surface of the steel strip injected from the circular tube nozzle 15. If possible, various forms can be used.

  Hereinafter, as a second embodiment of the present invention, a case where a nozzle for injecting a draining fluid as a draining means, in particular, a rod-shaped cooling water injection nozzle will be described instead of the pinch roll 11 in the first embodiment. . The rod-shaped cooling water as the draining means is not intended for cooling, but is injected in a pressurized state using the cooling water, like the rod-shaped cooling water from the circular tube nozzle 15 in the first embodiment. Since a continuous and straight water flow in which the cross section of the water flow from the nozzle outlet to the steel strip is maintained in a substantially circular shape is used, it is referred to as rod-shaped cooling water here.

  The configuration of the hot-rolled steel strip manufacturing facility in the second embodiment is substantially the same as that of the hot-rolled steel strip manufacturing facility in the first embodiment shown in FIG. The configuration around the cooling device 10 is as shown in FIG. That is, a cooling device main body 10b, which will be described later, is provided on the upper surface side of the run-out table 5, and a rod-shaped cooling water injection nozzle 19 as a draining means is provided on the downstream side thereof. The configuration on the lower surface side of the steel strip is the same as that in the first embodiment.

  And the structure of the cooling device main body 10b is as shown in FIG. Similar to the cooling device main body 10a of the first embodiment, the circular tube nozzles 15 arranged in the cooling water nozzle header 14 at a predetermined pitch (for example, 60 mm pitch) in the steel strip width direction are predetermined in the steel strip traveling direction. A predetermined number of columns (for example, 100 columns) is provided at a pitch of 100 mm (for example, 100 mm pitch), and the circular tube nozzle 15 directs the rod-shaped cooling water toward the traveling direction of the steel strip 12 at a predetermined injection angle θ (for example, , Θ = 50 °). However, in the cooling device main body 10a of the first embodiment, each row of circular tube nozzles is connected to the cooling water supply pipe 16 via one cooling water nozzle header 14 and each cooling water supply pipe 16 is independent. However, in the cooling device main body 10b of the second embodiment, every two rows of circular tube nozzles are connected to the cooling water supply pipe 16 via one cooling water nozzle header 14. With this as a control unit, each cooling water supply pipe 16 can be independently controlled on and off. The concept of the diameter, jet angle, nozzle height, etc. of the circular tube nozzle 15 is the same as that of the first embodiment.

  Note that, regarding the configuration of the cooling device main body 10b, the cooling device main body 10b performs on / off control using two rows of circular nozzles as control units. The purpose of carrying out this on-off control is to adjust the temperature at the end of cooling, but it can be turned on / off depending on how much cooling can be performed to turn on one row of nozzles and the allowable accuracy of the cooling end temperature is set. A control unit (number of nozzle rows) for performing control is determined. In the case of the configuration as described above, there is an ability to cool about 1 to 3 ° C. per row of circular tube nozzles. For example, when aiming at a temperature accuracy of ± 5 ° C., if it can be turned on and off with a resolution of about 5 to 10 ° C. Temperature range. Therefore, in this embodiment, if 5 ° C. is adjusted by one on-off, the temperature can be adjusted with sufficient accuracy if the two rows of circular tube nozzles can be turned on / off by turning on / off one cooling water supply pipe 16. Is possible. In addition, if on / off control is performed using a plurality of rows of circular tube nozzles as control units in this way, the number of shut-off valves, which are devices necessary for performing on / off control, can be reduced, and the number of pipes can be reduced. This makes it possible to manufacture equipment at low cost.

  Incidentally, in this embodiment, a mechanism capable of on / off control using two circular tube nozzles as a control unit has been described. However, a larger number of rows can be used as a control unit as long as necessary temperature accuracy can be maintained. It doesn't matter. Further, the control unit (number of rows of circular tube nozzles) in one on-off mechanism may be changed depending on the location with respect to the longitudinal direction (steel strip traveling direction).

  On the other hand, the rod-shaped cooling water injection nozzle 19 which is a draining means is disposed upstream of the cooling device body 10b with a predetermined nozzle diameter (for example, an inner diameter of 5 mm) and a nozzle pitch (for example, 40 mm). The rod-shaped cooling water inclined toward the 10b side (downstream side) is jetted. The angle η formed by the rod-shaped cooling water sprayed from the rod-shaped cooling water spray nozzle 19 and the steel strip 12 can be applied to a concept similar to the above-described jet angle θ of the rod-shaped cooling water from the cooling device body 10a (10b). , 60 ° or less is preferable. When the injection angle η exceeds 60 °, the speed component in the traveling direction of the cooling water (residual water) after reaching the steel strip 12 becomes small, and rod-like cooling injected from the cooling device body 10b on the downstream side thereof. Interference with water prevents the flow of stagnant water, thereby causing a part of the stagnant water to flow upstream of the rod-shaped cooling water from the rod-shaped cooling water jet nozzle 19, and the risk that the cooling region is not stable Because there is. Furthermore, the rod-shaped cooling water injection nozzle 19 injects toward the downstream side in the steel strip traveling direction. However, the stagnant water leaks in the steel strip traveling direction due to the shearing force generated between the steel strip and the stagnant water. It tends to be easy. Therefore, the stagnant water is unlikely to leak to the upstream side of the steel strip from the beginning, so it may be larger than the jet angle θ of the rod-shaped cooling water from the cooling device main body 10b installed downstream in the traveling direction within 5 °.

  Further, the rod-shaped cooling water sprayed from the rod-shaped cooling water spray nozzle 19 needs a force that does not flow out upstream by receiving the rod-shaped cooling water from the cooling device main body 10b. For this reason, when the number of rows of the circular tube nozzles 15 of the cooling apparatus main body 10b is large, it is preferable to increase the flow rate, flow velocity, and water pressure from the rod-shaped cooling water injection nozzle 19 to stabilize the draining ability. Alternatively, as shown in FIG. 5, a plurality of rows (for example, 5 rows) of rod-shaped cooling water injection nozzles 19 of the draining means are installed in the direction of travel of the steel strip, and according to the number of rows used of the circular tube nozzles 15 of the cooling device body 10b. Thus, the number of rows of the rod-shaped cooling water spray nozzles 19 used may be changed.

  However, since a plurality of rod-shaped cooling water injection nozzles 19 are installed side by side in the width direction, a gap is generated in the width direction between the injected rod-shaped cooling water, and there is a risk that the accumulated water leaks from the gap. Therefore, when the rod-shaped cooling water injection nozzle 19 is used, a plurality of rows are installed in the steel strip traveling direction as shown in FIG. 5, and the circular pipe nozzle of the cooling device main body 10a (10b) shown in FIGS. Similarly to the arrangement of 15, it is preferable that the width direction collision position of the rod-shaped cooling water in the next row is shifted from the width direction collision position of the rod-shaped cooling water in the previous row. As a result, the rod-shaped cooling water in the next row collides with a portion where the drainage capability is weakened between the rod-shaped cooling waters adjacent in the width direction, and the drainage capability cooling is complemented.

  And the cooling device main body 10b and the rod-shaped cooling water injection nozzle 19 are the rod-shaped cooling water injected from the circular pipe nozzle arrange | positioned at the foremost row (row on the most upstream side) of the cooling device main body 10b. Is adjusted so that the rod-shaped cooling water injected from the rod-shaped cooling water injection nozzle 19 in the last row (the most downstream row) is downstream (for example, 100 mm) from the position where the steel plate 12 is reached. Yes.

  As a result, also in the second embodiment, as in the first embodiment, when there is stagnant water on the upper surface of the steel strip as in the conventional cooling device using the free fall flow from the circular laminar nozzle. The problem that the cooling capacity is different in some cases and the cooling water that falls on the steel strip freely spreads back and forth and left and right, changes the cooling area, and the problem that the cooling capacity is not stable is solved, and it is highly stable Cooling capacity can be obtained. For example, rapid cooling exceeding a cooling rate of 100 ° C./s is possible for a steel strip having a thickness of 3 mm.

  In addition, when the steel strip 12 is thin and the passage of the steel strip 12 becomes unstable due to the influence of the cooling water, the cooling water is supplied at an injection pressure that does not hinder the passage of the tip of the steel strip 12. It is possible to change the pressure to a predetermined injection pressure after the steel strip has been injected and the tip of the steel strip has bitten into the coiler. In addition, in a steel strip having a large plate thickness (for example, a plate thickness of 2 mm or more), the tip of the steel strip may be passed through where the cooling water has been previously jetted. If it carries out like this, predetermined cooling will be attained from the front-end | tip of the steel strip 12. FIG.

  Here, 2nd Embodiment demonstrated the example using the nozzle which injects rod-shaped cooling water as a nozzle which injects the fluid for draining which is a draining means. As the draining means, a nozzle that ejects rod-shaped cooling water with a high momentum is preferable from the viewpoint of keeping the rod-shaped cooling water from the cooling device main body 10b, but it is not always necessary to be a nozzle that ejects rod-shaped cooling water. A nozzle that injects a slit flow may be used. Moreover, the injection speed of the cooling water from the nozzle outlet may be less than 7 m / s, or the cooling water may be in a droplet form to some extent without being continuous. For this reason, as described in the first embodiment, when used as a draining means, it is sufficient that there is a momentum to push back the cooling water sprayed from the cooling device main body 10b, and the water film of the staying water is broken. This is because it is not necessary to reach the steel strip 12 with fresh cooling water.

  In the above first and second embodiments, as shown in FIG. 1, the example in which the conventional cooling device 6 and the cooling device 10 of the present invention are arranged in this order on the run-out table 5 has been described. According to the first and second embodiments, since the steel strip is cooled to some extent by the conventional cooling device 6, uniform and stable cooling can be performed by the cooling device 10 of the present invention. The cooling stop temperature can be made uniform over the entire length. Further, when remodeling an existing hot rolling line, it is only necessary to add the cooling device 10 of the present invention downstream of the conventional cooling device 6, which is advantageous in terms of cost. However, the present invention is not limited to this embodiment. For example, the conventional cooling device 6 and the cooling device 10 of the present invention may be reversed, and only the cooling device 10 of the present invention is used. May be provided.

  Furthermore, this invention is good also as embodiment (3rd Embodiment) as shown in FIG. In this embodiment, in the first and second embodiments described above, a strong force is provided between the final finishing mill 4E and the cooling device 6 so as to be close to a steel strip as described in Patent Document 3, for example. A cooling device 17 and a pinch roll 18 that can be cooled are added, and the facility is suitable for the production of duplex stainless steel that requires two-stage cooling immediately after finish rolling and immediately before winding. In addition, it is also possible to cool by injecting using the conventional cooling device 6 between two cooling devices as needed. In some cases, the conventional cooling device 6 may not be provided.

  Also in this embodiment, similarly to the first and second embodiments, two-stage cooling can be performed uniformly from the tip of the steel strip 12 to the tail end, and the quality of the steel strip 12 is stabilized. Along with this, the steel strip cutting cost is reduced and the yield is increased.

(Invention Example 1)
As Example 1 of the present invention, the present invention was implemented based on the first embodiment. That is, the equipment configuration shown in FIG. 1 is used, and the cooling device main body 10a enables on-off control of the rod-shaped cooling water with one row of nozzles as a control unit as shown in FIG. As described above, the width direction mounting position of the next row was shifted from the previous row width direction mounting position by a distance of ½ the nozzle width direction mounting pitch. Moreover, as shown in FIG. 2, the pinch roll 11 was installed in the upstream of the cooling device main body 10a.

  Then, a steel strip with a finishing plate thickness of 2.8 mm is used, and the steel strip speed at the exit of the finishing mill 4 is 700 mpm at the tip of the steel strip, and after the tip of the steel strip reaches the winder 13, the speed is gradually increased. The speed was increased up to 1000 mpm (16.7 m / s). The temperature of the steel strip at the exit of the finish rolling mill 4 is 850 ° C., and is cooled to about 650 ° C. using the conventional cooling device 6, and thereafter the cooling device 10 of the present invention is used until the target winding temperature of 400 ° C. Used to cool. The allowable temperature deviation of the coiling temperature was ± 20 ° C.

  At that time, the injection angle θ of the circular tube nozzle 15 was set to 50 °, and rod-shaped cooling water was injected from the circular tube nozzle 15 at an injection speed of 30 m / s. The distance between the pinch roll 11 and the table roller 8 was previously set to a plate thickness of −1 mm (ie, 1.8 mm).

  And when the steel strip tip was passed in the state which injected rod-shaped cooling water on the predetermined conditions beforehand, and the steel strip tip was taken up by winder 13 and tension was applied, pinch roll 11 was raised 2 mm. Even in this state, the cooling water on the steel strip hardly slips to the upstream side of the pinch roll 11, and good drainage was realized by the pinch roll 11. In addition, the steel strip was not scratched or loosened.

  Then, the number of rows of the circular tube nozzles 15 for injecting the rod-shaped cooling water is determined based on the traveling speed of the steel strip, the measured temperature value of the steel strip, and the cooling temperature amount up to the target cooling stop temperature, and the obtained circular tube nozzle The number of rows of 15 was set so as to be preferentially ejected from the side closer to the pinch roll 11. After that, as the traveling speed of the steel strip 12 increased, the row of circular pipe nozzles 15 for injecting rod-shaped cooling water was extended downstream.

  As a result, in Example 1 of the present invention, the steel strip temperature in the winder 13 is within 400 ° C. ± 10 ° C., and extremely uniform cooling is realized from the tip of the steel strip to the tail end within the target temperature deviation. I was able to.

(Invention Example 2)
As Invention Example 2, the present invention was implemented based on the second embodiment. That is, as described above, the equipment configuration is almost the same as the equipment configuration shown in FIG. 1, and the cooling device main body 10b is turned on and off as shown in FIG. As shown in FIG. 8B, the width direction mounting position of the next row is shifted by a distance of ½ of the nozzle width direction mounting pitch with respect to the width direction mounting position of the previous row. did. In addition, as shown in FIG. 5, a plurality of rows of rod-shaped cooling water injection nozzles 19 serving as nozzles for injecting a draining fluid are installed on the upstream side of the cooling device main body 10b.

  Then, a steel strip with a finishing plate thickness of 2.8 mm is used, and the steel strip speed at the exit of the finishing mill 4 is 700 mpm at the tip of the steel strip, and after the tip of the steel strip reaches the winder 13, the speed is gradually increased. The speed was increased up to 1000 mpm (16.7 m / s). The temperature of the steel strip at the exit of the finish rolling mill 4 is 850 ° C., and is cooled to about 650 ° C. using the conventional cooling device 6, and thereafter the cooling device 10 of the present invention is used until the target winding temperature of 400 ° C. Used to cool. The allowable temperature deviation of the coiling temperature was ± 20 ° C.

  At that time, the injection angle θ of the circular tube nozzle 15 of the cooling device main body 10b was set to 50 °, and the rod-shaped cooling water was injected from the circular tube nozzle 15 at an injection speed of 35 m / s.

  On the other hand, the injection angle η of the rod-shaped cooling water injection nozzle 19 which is a draining means is 50 °, and the same angle as the circular tube nozzle 15 of the cooling device main body 10b.

  And based on the progress speed of the steel strip, the temperature measurement value of the steel strip, and the cooling temperature amount to the target cooling stop temperature, the number of rows of the circular tube nozzles 15 for injecting the rod-shaped cooling water in the cooling device main body 10b is obtained, The number of rows of the circular tube nozzles 15 thus determined was set to be preferentially ejected from the front row (row on the most upstream side). Thereafter, as the traveling speed of the steel strip 12 increased, the row of circular tube nozzles 15 for injecting rod-shaped cooling water in the cooling device main body 10b was extended downstream. Further, the rod-shaped cooling water injection nozzle 19 is set so as to be preferentially injected from the last row (the most downstream row), and the rod-shaped cooling water nozzle 19 is changed according to the change in the number of rows of the circular tube nozzles 15 used in the cooling device main body 10b. The amount of water in the water injection nozzle 19 was increased, and when the flow rate of the rod-shaped cooling water injection nozzle 19 reached the upper limit of the equipment in the process, the row of the rod-shaped cooling water injection nozzles 19 to be sequentially injected was increased upstream. .

  At that time, the steel strip tip was passed in a state in which the rod-shaped cooling water was jetted under predetermined conditions in advance, but the cooling water on the steel strip slips to the upstream side of the rod-shaped cooling water from the rod-shaped coolant spray nozzle 19. The rod-shaped cooling water spray nozzle 19 realized a good drainage.

  As a result, in Example 2 of the present invention, the steel strip temperature in the winder 13 is within 400 ° C. ± 18 ° C., and within the target temperature deviation, very uniform cooling is realized from the tip of the steel strip to the tail end. I was able to.

(Comparative example)
On the other hand, as a comparative example, the steel strip was cooled without using the cooling device 10 of the present invention in the equipment shown in FIG. In that case, it cooled to 400 degreeC which is target winding temperature using only the conventional cooling device 6. FIG. The allowable temperature deviation of the winding temperature was ± 20 ° C. The other conditions are the same as in the first invention example.

  As a result, in the comparative example, hunting of the cooling temperature was observed in the longitudinal direction of the steel strip. This is presumed that the staying water stays in the portion where the steel strip becomes the sled, thereby causing uneven temperature in the longitudinal direction. For this reason, the steel strip temperature in the winder 13 greatly varies from 300 ° C. to 420 ° C. with respect to the target temperature deviation (± 20 ° C.), thereby causing a large variation in strength within the steel strip.

It is a block diagram of the rolling equipment in the 1st, 2nd embodiment of this invention. It is a block diagram of the cooling device in the 1st Embodiment of this invention. It is detail drawing of the cooling device in the 1st Embodiment of this invention. It is a block diagram of the cooling device in the 2nd Embodiment of this invention. It is detail drawing of the cooling device in the 2nd Embodiment of this invention. It is a block diagram of the cooling device in the 2nd Embodiment of this invention. It is a figure explaining the collision position of the cooling device of this invention. It is detail drawing of the rod-shaped cooling water injection nozzle of the cooling device main body in the 1st, 2nd embodiment of this invention, and the draining means in 2nd Embodiment. It is a block diagram of the rolling equipment in the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Coarse rolling mill 2 ... Coarse bar 3 ... Table roller 4 ... Continuous finish rolling mill group 4E ... Final finishing mill 5 ... Run-out table 6 ... Cooling device 7 ... Circular pipe laminar nozzle 8 ... Table roller 9 ... Spray nozzle 10 ... Cooling device 10a ... Cooling device body 10b ... Cooling device body 11 ... Pinch roll 12 ... Steel strip 13 ... Winding machine 14 ... Cooling water nozzle header 15 ... Circular nozzle 16 ... Cooling water supply pipe 17 ... Proximity type cooling device 18 ... Pinch roll 19 ... Rod-shaped cooling water injection nozzle as draining means

Claims (11)

A hot-rolled steel strip cooling device for cooling the hot-rolled steel strip after finish rolling conveyed on the run-out table,
On the upper surface side of the steel strip, a plurality of cooling nozzles that inject the rod-shaped cooling water so that the injection angle is inclined toward the upstream side in the traveling direction of the steel strip, and
A cooling device for a hot-rolled steel strip, wherein a draining means for draining the cooling water on the upper surface of the steel strip injected from the cooling nozzle is arranged on the upstream side. A plurality of the cooling nozzles are arranged in the steel strip width direction, and a plurality of rows are arranged in the steel strip traveling direction,
The width direction positions of the cooling nozzles arranged in each row are arranged such that the width direction position in the upstream row and the width direction position in the downstream row are shifted from each other. The hot-rolled steel strip cooling apparatus as described.   The apparatus for cooling a hot-rolled steel strip according to claim 1 or 2, wherein an angle formed between the rod-shaped cooling water sprayed by the cooling nozzle and the steel strip is 55 ° or less.   The cooling device for a hot-rolled steel strip according to claim 2 or 3, wherein the cooling nozzle row is capable of independently controlling on / off of cooling water using one or more rows as control units.   5. The cooling device for a hot-rolled steel strip according to any one of claims 1 to 4, wherein the draining means is a pinch roll that is driven to rotate up and down so as to roll on the steel strip.   The draining means is one or more nozzles for ejecting a draining fluid from a slit-shaped or circular nozzle ejection port so that the spray angle is inclined toward the downstream side in the traveling direction of the steel strip. The cooling device for a hot-rolled steel strip according to any one of claims 1 to 4. A method for cooling a hot-rolled steel strip after finish rolling conveyed on a run-out table,
While inclining toward the upper surface side of the steel strip toward the upstream side in the direction of travel of the steel strip and injecting rod-shaped cooling water,
A method for cooling a hot-rolled steel strip, characterized in that cooling water is drained by a draining means provided on the upstream side.   The method for cooling a hot-rolled steel strip according to claim 7, wherein the cooling capacity is controlled by changing the length of the cooling zone by controlling the number of nozzle rows in the traveling direction of the steel strip through which the rod-shaped cooling water is injected. . A pinch roll is used for the draining means, and the pinch roll is preliminarily set with a gap equal to or less than the thickness of the steel strip, and starts to inject cooling water after the steel strip tip is pinched,
9. The method of cooling a hot-rolled steel strip according to claim 7 or 8, wherein the pinch roll is slightly raised while rotating the tip of the steel strip almost simultaneously with the coiler.   A nozzle that injects a draining fluid from a slit-shaped or circular nozzle injection port that is inclined toward the downstream side in the traveling direction of the steel strip is used as the draining means, and is injected while being inclined toward the upstream side in the traveling direction of the steel strip. One or more of the amount of water, the water pressure, and the number of rows of spray nozzles in the nozzle that ejects the draining fluid is changed according to the number of rows of rod-shaped cooling water spray nozzles. 9. The method for cooling a hot-rolled steel strip according to 8.   The control of the number of nozzle rows in the steel strip traveling direction that inclines toward the upstream side in the traveling direction of the steel strip and injects rod-shaped cooling water is performed by preferentially injecting the nozzle row on the draining means side, and the nozzle on the downstream side The method for cooling a hot-rolled steel strip according to any one of claims 8 to 10, wherein the length of the cooling zone is changed by sequentially turning on and off the rows.

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