JP2011005538A - Cooling apparatus for hot-rolled steel plate, and dewatering method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling apparatus for a hot-rolled steel plate and a dewatering method thereof which can eliminatr the adverse effect affected by residual water on the surface of a steel plate in a cooling zone through which the steel plate is passed without flowing cooling water.SOLUTION: The cooling system includes a plurality of cooling zones which includes water cooling apparatus which are lined up in the conveying direction of the steel plate and also with which the water is respectively blown onto the surfaces of the steel plate. Each water cooling apparatus 4, 5 has water jetting devices as a part of it, in which the jetting direction of the water is inclined in the opposite direction to the conveying direction of the steel plate S and also the water is blown in the whole region in the width direction of the steel plate. In a cooling zone situated next to the cooling zones N1-Nm which are set to perform the water cooling, by blowing the water to the steel plate from the water jetting device which is possessed with the water cooling apparatus in the cooling zone, the residual water is removed.

Description

  The present invention relates to a cooling technique for a steel sheet after hot rolling such as production of a thick steel sheet, and more particularly to a draining technique for removing water remaining on the surface of the steel sheet.

  In controlled rolling in which cooling and rolling are combined, and in controlled cooling in which cooling is performed while being transferred online, a highly accurate temperature control device for the steel sheet is important. In particular, in the case of a thick steel plate, since a large amount of cooling water is used for cooling, it is important to dam and drain the cooling water on the outlet side of each cooling zone and to remove residual water on the steel plate. For this reason, conventionally, various techniques have been studied regarding the technique of draining the steel sheet surface.

For example, in the technique of Patent Document 1, a side spray for draining water is provided on one side in the width direction of a steel sheet transferred on a table roller. And the spray water is sprayed from the side spray, and the residual water on the steel plate surface is excluded.
In addition to the technique of removing residual water on the surface of the steel sheet, which could not be removed by the draining roll after the final cooling stage, by air purge installed directly above the steel plate passage part, it is disclosed in Patent Document 2 Discloses a technique for removing residual water on a steel plate using a brush.

JP-A-7-9023 Japanese Utility Model Publication No. 60-74803

When spray water is sprayed from one side in the width direction of the steel sheet as in the technique described in Patent Document 1, residual water tends to stay on the side opposite to the spray water spray side. For this reason, the steel plate surface opposite to the staying side, that is, spray injection, in the steel plate width direction is cooled. As a result, temperature deviation occurs in the width direction of the steel sheet, and thermal distortion occurs.
Moreover, in the draining using a brush like the technique of patent document 2, although the above-mentioned width direction deviation is eliminated, there exists a possibility of damaging the steel plate surface with a brush. In addition, there is a problem that maintenance and management of the brush is time-consuming and expensive.

Here, the cooling equipment for hot-rolled thick steel plates is usually configured by arranging cooling zones with water cooling equipment composed of water cooling nozzles, etc. In some or all of the cooling zone, rapid cooling (accelerated cooling) is performed by water cooling on the steel sheet to be conveyed. Here, a cooling zone for performing water cooling is referred to as a water cooling zone.
In this cooling facility, draining rolls are usually provided on the entry side and the exit side of each cooling zone. This draining roll is provided in order to prevent the residual water on the surface of the steel sheet from flowing from the adjacent water cooling zone, or to prevent the cooling water in the own zone from flowing out to the adjacent cooling zone. That is, this draining roll is installed in order to avoid an unintended cooling effect on the steel sheet due to residual water on the steel sheet surface.

  However, a gap is formed between the surface of the steel sheet and the draining roll due to the vertical balance caused by the crown of the steel sheet and the warpage (upward warping, lower warping, etc.) of the steel sheet. Due to this gap, residual water that cannot be completely purged by the draining roll may be transferred to the subsequent cooling zone. When the subsequent cooling zone is a slow cooling zone that is not a water cooling zone, only the portion on which the residual water is placed is partially cooled.

In particular, in recent years, accelerated cooling technology has advanced, and accordingly, the requirements on the material design for steel plate cooling behavior control have become strict, and a zone where water cooling is not carried out, that is, a cooling zone where plates are passed without flowing cooling water ( The adverse effect of residual water on the steel sheet surface in the slow cooling zone) has become a problem.
The present invention pays attention to the above points, and provides a cooling facility for hot-rolled steel sheet and a method for draining the hot-rolled steel sheet that can eliminate the adverse effect of residual water on the steel sheet surface in a cooling zone that passes through without flowing cooling water. The challenge is to do.

In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention is a cooling facility for cooling while transporting a steel sheet after hot rolling, and is arranged in the steel sheet transport direction and has water on each steel sheet surface. In a cooling facility for hot-rolled steel sheets, comprising a plurality of cooling zones equipped with water-cooling equipment capable of spraying, and setting the cooling zone for water cooling according to the steel sheet to be cooled,
Each of the above water cooling facilities has a water injection device that, as a part thereof, has a water injection device capable of spraying water over the entire width direction of the steel sheet while the water injection direction is inclined in the direction opposite to the conveying direction of the steel sheet, and is set when water cooling is performed. In a cooling zone that is positioned after the cooling zone that has not been set when water cooling is performed, a water draining control unit that controls water to be sprayed onto the steel sheet from the water injection device of the water cooling equipment in the cooling zone is provided. It is characterized by.

Next, the invention described in claim 2 is characterized in that a draining roll is provided between the cooling zones in the configuration described in claim 1.
Next, the invention described in claim 3 is characterized in that, with respect to the configuration described in claim 1 or claim 2, the water injection device is arranged on the most upstream side in the corresponding water cooling facility. Is.

Next, the invention described in claim 4 is the configuration described in any one of claims 1 to 3, wherein the water-cooling equipment in each cooling zone is respectively up and down across the position of the steel plate to be transported. Arranged,
In the cooling zone that was not set when the water cooling was performed, water was sprayed on the upper surface of the steel sheet from the water injection device of the upper water cooling equipment to remove residual water on the steel sheet surface, and the water injection of the lower water cooling equipment Water is sprayed on the lower surface of the steel plate from the apparatus as well.

Next, the invention described in claim 5 is to cool the steel sheet after hot rolling by passing through a plurality of cooling zones that can be water-cooled in the steel sheet conveying direction.
Using a part of the water-cooling nozzle located in the cooling zone that does not perform water cooling in the latter stage of the cooling zone that performs water cooling, spraying water in a direction opposite to the steel plate conveyance direction, and spraying water on the surface of the steel plate The present invention provides a draining method characterized by removing water.
Next, the invention described in claim 6 is directed to the configuration described in claim 5 by using a part of the water cooling nozzle disposed in the cooling zone in which the water cooling is not performed, and is opposite to the steel plate conveyance direction. In addition to removing residual water on the upper surface of the steel sheet by inclining in the direction and spraying water on the upper surface of the steel sheet, the water is also sprayed on the lower surface of the steel sheet by inclining in the direction opposite to the steel sheet conveying direction. is there.

Here, in the following description, among the cooling zones, a cooling zone that performs water cooling is also referred to as a water cooling zone, and a cooling zone that does not perform water cooling is also referred to as a slow cooling zone.
According to the invention which concerns on Claim 1 or Claim 5, it is a water injection apparatus in which the water injection direction inclines in the reverse direction to the conveyance direction of a steel plate, and can spray water to the whole width direction of a steel plate. Remove the transferred residual water.
At this time, by spraying water over the entire area of the steel plate width direction, it becomes possible to remove the residual water on any of the steel plate widths. Moreover, the water injection direction inclines in the direction opposite to the conveying direction of the steel sheet, so that the water movement to the downstream side can be suppressed.

Further, since the residual water is removed using a part of the water cooling equipment, it is not necessary to provide equipment for draining (purging) the residual water separately from the water cooling equipment in the cooling zone.
Here, as a means for removing the residual water on the steel sheet surface, there is a so-called gas purge in which a gas such as compressed air is blown onto the steel sheet surface. However, in the case of this gas purging, it is necessary to install gas piping for gas purging and spraying equipment separately from the cooling water piping / equipment for water cooling in the cooling zone. The current situation is not applicable.

Moreover, in the invention which concerns on Claim 2, the residual water which remains after draining with a draining roll is removed with a water injection apparatus. Therefore, the water injection pressure (or the amount of water sprayed per unit time) injected from the water injection device for draining can be set to be significantly reduced. Moreover, residual water can be removed more reliably.
Moreover, according to the invention which concerns on Claim 3, a water-injection apparatus is arrange | positioned in the most upstream in the corresponding cooling zone (slow cooling zone). For this reason, residual water is removed at or near the most upstream position of the cooling zone (slow cooling zone), and as a result, the adverse effect of residual water during steel plate cooling in the cooling zone (slow cooling zone) is further suppressed. I can do it.

When a water draining roll is provided, a water injection device in which the water injection direction inclines in the direction opposite to the conveying direction of the steel plate is arranged on the most upstream side, so that the front side can be used for rapid cooling in the water cooling zone. It leads to being able to supply cooling water more effectively toward the draining roll position located.
Moreover, according to the invention which concerns on Claim 4 or Claim 6, when draining the steel plate upper surface, by spraying an appropriate amount of water also on the steel plate lower surface (back surface), residual water from the previous cooling zone, and residual It is possible to balance the upper and lower sides of the plate with cooling by water sprayed on the upper surface of the steel plate for water removal, and it is possible to further suppress the occurrence of distortion after cooling.

It is a schematic structure figure explaining the equipment composition concerning the embodiment based on the present invention. It is a schematic block diagram explaining the cooling facility which concerns on embodiment based on this invention.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram illustrating the equipment configuration of the present embodiment.
(Constitution)
As shown in FIG. 1, a hot rolling process B is provided as a pre-process of the cooling facility A. The hot rolling process B includes a rolling mill 1 that performs hot rolling. In FIG. 1, the code | symbol 1 shows the finish rolling mill of the last stage.

Next, the cooling facility A will be described. A plurality of cooling zones N _{1 to} N _m are arranged so as to be aligned along the pass line P of the steel plate S (the conveying direction of the steel plate S). Further, the draining rolls 2 and 3 are disposed between each cooling zone _N 1 to N _m.
In each of the cooling zones N _{1 to} N _m , water cooling facilities 4 and 5 are arranged, respectively, as shown in FIG. The water cooling facilities 4 and 5 of this embodiment are laminar type acceleration cooling devices, and a plurality of water cooling nozzles 8a, 8b, 8c, 9a, 9b, and 9c are provided along the pass line P from the water cooling headers 6 and 7. Arranged. Further, the water cooling nozzles 8a, 8b, 8c, 9a, 9b, 9c are also arranged in the steel plate width direction, and the water cooling nozzles 8a, 8b, 8c, 9a, 9b, 9c are arranged in the steel plate width direction. The water to be sprayed is set so that water is uniformly sprayed over the entire width direction with respect to the surface of the steel sheet S.

Further, in the present embodiment, a water-cooled nozzle 8a which is arranged in each cooling zone _{N 1 ~N m, 8b, 8c} , 9a, 9b, water cooling nozzles 8a located most upstream among 9c, the water 9a group of The water injection direction is inclined so that the injection direction is opposite to the conveying direction of the steel sheet S. Each cooling zone _N 1 to N _m in a water-cooled nozzle 8a disposed, 8b, 8c, 9a, 9b, the injection direction of water the group of water-cooled nozzle 8c located most downstream among 9c is a steel sheet S The water injection direction is inclined in the transport direction. That is, the upstream and downstream water-cooling nozzles 8a, 8b, 9a, and 9b are inclined in the injection direction toward the draining rolls 2 and 3 that are close to each other.
Here, the group of the water-cooling nozzles 8a and 9a located on the most upstream side constitutes a water injection device.

In addition, the inclination angle of the said injection direction is set to the inclination angle of 1 degree or more, for example, and it sets so that water may be sprayed directly on the surface of the steel plate S.
Reference numeral 12 denotes a water supply pipe for supplying water to each of the water-cooled headers 6 and 7. A flow rate adjusting valve 10 is interposed in the water supply pipe 12, and the amount of water supplied to each of the water cooling headers 6, 7, that is, the cooling capacity in each water cooling zone is controlled by the flow rate adjusting valve 10. The flow rate adjusting valve 10 is controlled in accordance with a command from the controller 20.
Moreover, in this embodiment, the branch pipe 13 which supplies water to the water cooling nozzle 8a which comprises said each water injection apparatus is provided. The branch pipe 13 is provided with a second flow rate adjustment valve 11, and the amount of water supplied to the water cooling nozzle 8 a constituting the water injection device is controlled by the second flow rate adjustment valve 11. The second flow rate adjustment valve 11 is controlled according to a command from the controller 20.
Here, the water cooling facilities 4 and 5 are individually arranged above and below the pass line P.

Further, a thermometer for measuring the surface temperature of the steel sheet S at the completion of rolling is provided on the exit side of the final rolling mill 1, and the thermometer outputs the measured steel plate temperature to the controller 20. Further, thermometers (not shown) are also appropriately disposed in the cooling zones N _{1 to} N _m and the measured steel plate temperature is output to the controller 20.
The controller 20 includes a water cooling control unit 20A and a draining control unit 20B.
Information (sheet thickness and others) of the steel sheet S to be cooled is input to the controller 20.

The water cooling control unit 20A, based on the information and the steel plate temperature information of the steel plate S which is the input, and sets the cooling zone performs water cooling N ₁ ~N _{m-2 (water} cooling zone), a cooling of the respective water cooling zones The corresponding water supply control amount is calculated, and a command to be the calculated supply control amount is output to the corresponding flow rate adjustment valve 10. In addition, a close command is output to the flow rate adjusting valves 10 corresponding to the cooling zones N _m−1 and N _m where water cooling is not performed. It is assumed that the cooling zones N _{1 to} N _m-2 are water cooling zones, and N _m-1 and N _m are slow cooling zones.
Further, the draining control unit 20B outputs an opening command only to the second flow rate adjustment valve 10 in the cooling zone Nm _-1 next to the final water cooling zone Nm _-2 located on the most downstream side of the water cooling zone. In addition, when there is no slow cooling zone, the draining control part 20B does not operate.

(Operation, action and effect)
In the water cooling zone, water is jetted from the water cooling nozzles 8a, 8b, 8c, 9a, 9b, and 9c of each water cooling equipment, and the jetted water is prevented from moving to the adjacent cooling zone by the draining rolls 2 and 3. Thus, the steel sheet S portion passing through the water cooling zone is cooled.
At this time, when the steel sheet S moves from the final water-cooling zone N _m-2 to the next-stage slow cooling zone N _m-1 (slow cooling zone at the most upstream position), some of the water becomes residual water. It moves to the said slow cooling zone Nm _-1 in the state mounted on S upper surface. This residual water is usually present in a mottled pattern.

On the other hand, in this embodiment, the said residual water is removed with the water from the group of the water cooling nozzle 8a which comprises a water injection apparatus in the upstream position of the said slow cooling zone Nm _-1 .
As a result, the steel sheet S during the slow cooling is slowly cooled with no residual water.
In this way, the cooling water remaining on the surface of the steel sheet S that could not be removed by the draining rolls 2 and 3 is uniformly distributed over the entire width by using the cooling water from the group of water cooling nozzles 8a installed at equal intervals over the entire width. Purge can be done.

Furthermore, when the upper surface is drained, residual water from the front zone of the surface of the steel sheet S (upper surface) can be obtained by spraying an appropriate amount of water from the group of water cooling nozzles 9a on the rear surface (lower surface) of the steel sheet S to the lower surface of the steel sheet S. It is possible to balance the upper and lower sides of the plate with cooling by water for draining, and suppress the occurrence of distortion after cooling.
Here, in this embodiment, the case where the residual water is removed by the water injection device is illustrated in the slow cooling zone N _m-1 located on the most upstream side, but the slow cooling zone N located on the second upstream side. _{In m} , residual water may be removed by the water injection device.

Moreover, in the said description, although the case where all the back | latter stage of the draining zone was a slow cooling zone was illustrated, this embodiment is not limited to this. For example, the present invention can also be applied to the case where a set of “draining zone and slow cooling zone” is set a plurality of times along the steel plate conveyance direction. In this case, the above draining process may be applied to all or some of the slow cooling zones.
Moreover, in the said embodiment, although the water-cooling nozzles 8a and 9a and the other water-cooling nozzles 8b, 8c, 9b, and 9c are made into the same header, the water supplied to each header is adjusted separately as another header. Also good.

2,3 Draining rolls 4, 5 Water cooling equipment 6, 7 Water cooling headers 8a, 8b, 8c, 9a, 9b, 9c Water cooling nozzles 8a, 9a Water cooling nozzles (water injection devices)
10 flow regulating valve 11 second flow rate adjustment valve 20 controller 20A water cooling control unit 20B controller A cooling system B hot rolling step _N 1 to N _m each cooling zone _{N m-2} final water cooling zone _{N m-1, m} slow cooling Zone P Pass line S Steel plate

Claims (6)

A cooling facility for cooling while conveying the steel sheet after hot rolling,
In the cooling equipment for hot-rolled steel sheets, which is arranged in the steel sheet conveying direction and includes a plurality of cooling zones each equipped with a water cooling facility capable of spraying water on the steel sheet surface, and sets the cooling zone for performing water cooling according to the steel sheet to be cooled.
Each of the above water cooling facilities has, as a part thereof, a water injection device capable of spraying water over the entire width direction of the steel sheet while the water injection direction is inclined in the direction opposite to the conveying direction of the steel sheet,
A drainer for controlling water spraying to the steel plate from the water injection device of the water cooling equipment of the cooling zone in a cooling zone that is located after the cooling zone that is set for water cooling and that is not set for water cooling. A cooling facility for hot-rolled steel sheets, comprising a control unit.   The cooling facility for hot-rolled steel sheets according to claim 1, further comprising a draining roll between the cooling zones.   The said water injection apparatus is arrange | positioned in the most upstream in the corresponding water cooling equipment, The cooling equipment of the hot-rolled steel plate described in Claim 1 or Claim 2 characterized by the above-mentioned. The water cooling equipment in each cooling zone is arranged up and down across the steel plate position to be transported,
In the cooling zone that was not set when the water cooling was performed, water was sprayed on the upper surface of the steel sheet from the water injection device of the upper water cooling equipment to remove residual water on the steel sheet surface, and the water injection of the lower water cooling equipment The cooling equipment for hot-rolled steel sheets according to any one of claims 1 to 3, wherein water is sprayed on the lower surface of the steel sheet also from the apparatus. In cooling the steel plate after hot rolling by passing through a plurality of cooling zones that can be water-cooled in the steel plate conveyance direction,
Using a part of the water-cooling nozzle located in the cooling zone that does not perform water cooling in the latter stage of the cooling zone that performs water cooling, spraying water in a direction opposite to the steel plate conveyance direction, and spraying water on the surface of the steel plate A draining method characterized by removing water.   Using a part of the water-cooling nozzle arranged in the cooling zone that does not perform the water-cooling, the residual water on the upper surface of the steel sheet is removed by spraying water on the upper surface of the steel sheet by inclining in the direction opposite to the steel sheet conveying direction. In addition, the water draining method according to claim 5, wherein water is sprayed to the lower surface of the steel plate in a direction opposite to the steel plate conveyance direction.

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