JP2010064084A - Apparatus and method for cooling steel plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for cooling a steel plate capable of preventing any irregular cooling by shortening as far as possible the time before the feed of cooling water on the steel plate is actually started or stopped after a command for starting or stopping the feed of cooling water is issued, and by avoiding any unnecessary spouting of cooling water from a nozzle. <P>SOLUTION: The apparatus for cooling the steel plate comprises a nozzle header 1 connected to a cooling water feed source via a cooling water feed pipe 6, a cooling water feed control means 7 provided to the cooling water feed pipe 6, and a nozzle 5 fitted to the nozzle header 1. The nozzle header 1 comprises an outer pipe 2 and an inner pipe 3. One end of the cooling water feed pipe 6 penetrates the outer pipe 2 and is connected to the inner pipe 3, and a cooling water blocking mechanism 9 to be operated by the pressure is provided to the nozzle 5. Further, the nozzle header has a cooling water discharge pipe 11 connected to the inner pipe 3 to discharge the cooling water from the inside of the nozzle header 1 to the outside of the presence area of the steel plate, and a cooling water discharge control means 12 provided to the cooling water discharge pipe 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a steel plate cooling device and a cooling method.

  In the process of manufacturing a steel sheet by hot rolling, it is common to supply cooling water or air cooling to control the rolling temperature, but in recent years, cooling water has been injected to increase the cooling rate. The development of technology to increase the strength of steel sheets by refining the structure has been thriving.

  When cooling a steel sheet immediately after rolling through a cooling device, generally, the inlet side of the cooling device has a temperature distribution in the longitudinal direction of the steel plate due to the air cooling time. That is, the maximum temperature of the steel sheet is in the vicinity of its front end (for example, about 840 ° C.), and the minimum temperature of the steel sheet is in the vicinity of its rear end (for example, about 770 ° C.). In order to obtain a uniform material in the steel sheet, it is important to make the cooling stop temperature uniform in the steel sheet, but for that purpose, during cooling, so as to cancel the temperature difference on the inlet side of the cooling device, It is necessary to control the cooling in the longitudinal direction of the steel sheet.

  Regarding this problem, a method of changing the cooling capacity by changing the flow rate of the cooling water from the cooling device is usually adopted, but particularly in the portion where the temperature drop at the front and rear ends of the steel plate is significant. It is necessary to control the cooling by stopping the supply of the cooling water from the cooling nozzle.

  With regard to such cooling control, the excellent responsiveness of the cooling device is important. The time from when the cooling water supply start command is issued until the cooling water is actually supplied to the steel sheet (cooling water start delay time) ), And the time (cooling water stop delay time) from when the cooling water supply stop command is issued until the cooling water supply to the steel plate is actually stopped must be short.

  Regarding the steel plate cooling device having excellent responsiveness as described above, Patent Document 1 stops the supply of cooling water into the header, and at the same time, provides a columnar rotating body at the nozzle outlet and rotates it. Thus, a method of shutting off the cooling water supplied from the water tank to avoid unnecessary cooling water from the nozzle outlet and improving the on / off characteristics is disclosed.

  Patent Document 2 discloses a method of shutting off the supply of cooling water inside a water tank that supplies cooling water to a slit nozzle.

  Further, Patent Document 3 avoids unnecessary cooling water from the nozzle outlet by providing a movable frame at the downstream portion of the slit nozzle and providing a shielding lid capable of shielding the nozzle outlet. Thus, a method for improving on-off characteristics is disclosed.

Furthermore, Patent Document 4 has a double structure of an inner pipe and an outer pipe in the header, holds cooling water in the header inner pipe, and passes only water remaining in the gap between the header outer pipe and the inner pipe to the outside through the nozzle. Discloses how it is discharged.
JP-A-55-54210 JP-A-53-30912 JP-A-55-54209 JP-A-10-192944

  However, as in Patent Documents 1 and 2, only by the method of shutting off the cooling water at the outlet of the slit nozzle or inside the water tank, the use of the nozzle for a long period of time damages the seal portion that causes the cooling water to be shielded. It becomes imperfect and the proper shielding effect cannot be obtained. In particular, in a wide slit nozzle having a plate width as long as 5 m, such as a thick steel plate, the shielding mechanism is structurally difficult and not practical.

  Further, as in Patent Document 3, in the method of providing a lid that can be opened and closed at the outlet of the slit nozzle, the mechanism for opening and closing becomes complicated, and as a result, there is a problem that the equipment cost increases. It was. Moreover, even if the method of Patent Document 3 is applied, it is not possible to avoid water leakage from the seal portion due to long-term use, which causes uneven cooling.

  Further, in the method of Patent Document 4, if the piping to be supplied to the header inner pipe is above the header, the cooling water flowing from the supply pipe to the header inner pipe due to gravity is removed even if the cooling water supply is stopped. As a result, the cooling water leaked from the nozzle, and an excellent off-characteristic could not be obtained.

  Accordingly, an object of the present invention is to have excellent responsiveness, and extremely shorten the time from when a cooling water supply start command or a stop command is issued until the cooling water supply to the steel plate actually starts or stops. In addition, cooling of the steel plate that avoids unnecessary cooling water from the nozzle outlet and prevents leakage of cooling water from the nozzle outlet even when used for a long period of time, thus preventing uneven cooling. An object of the present invention is to provide an apparatus and a cooling method, that is, a steel sheet cooling apparatus and a cooling method capable of uniformly and stably water-cooling a steel sheet at a high cooling rate.

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

[1] A nozzle header disposed in the vicinity of the steel plate and connected to a cooling water supply source via a cooling water supply pipe, cooling water supply control means provided in the cooling water supply pipe, and attached to the nozzle header In the steel sheet cooling device comprising the nozzles formed,
The nozzle header includes an outer tube and an inner tube that is disposed inside the outer tube so as to form a space between the outer tube and has a through hole in an upper portion, and is one end of the cooling water supply tube. Is connected to the inner pipe through the outer pipe of the nozzle header,
The nozzle has a cooling water shut-off mechanism that operates by pressure, and is connected to the inner pipe and discharges the cooling water from the nozzle header to the outside of the area where the steel sheet exists, and the cooling water discharge pipe A cooling apparatus for a steel sheet, comprising a cooling water discharge control means provided.

  [2] The steel sheet cooling apparatus according to [1], further including pressure detection means for detecting a water pressure acting on the cooling water blocking mechanism.

[3] A method for cooling a steel sheet using the cooling device according to [1],
When starting the supply of the cooling water onto the steel plate, the cooling water supply control means is opened, and at the same time or in advance, the cooling water discharge control means is closed to act on the cooling water blocking mechanism. When the water pressure exceeds a predetermined pressure, the cooling water shut-off mechanism takes the opening action, and the cooling water is ejected from the nozzle,
When stopping the supply of the cooling water on the steel plate, the cooling water supply control means is closed and at the same time the cooling water discharge control means is opened so that the pressure acting on the cooling water shut-off mechanism is a predetermined pressure. A cooling method for a steel sheet, characterized in that when the pressure falls below the pressure, the cooling water shut-off mechanism takes a shut-off action to shut off the cooling water from the nozzle.

[4] A method of cooling a steel sheet using the cooling device according to [2],
When starting the supply of the cooling water onto the steel plate, the cooling water supply control means is opened, and at the same time or in advance, the cooling water discharge control means is closed to act on the cooling water blocking mechanism. When the water pressure exceeds a predetermined pressure, the cooling water shut-off mechanism takes the opening action, and the cooling water is ejected from the nozzle,
When stopping the supply of the cooling water on the steel plate, the cooling water supply control means is closed and at the same time the cooling water discharge control means is opened so that the pressure acting on the cooling water shut-off mechanism is a predetermined pressure. When the pressure falls below the pressure, the cooling water shut-off mechanism takes a shut-off action to shut off the cooling water from the nozzle, and when the detected value of the pressure detecting means falls below a predetermined pressure, the cooling water discharge control means A method for cooling a steel sheet, characterized in that a closing operation is performed.

  By using the present invention, the time from when the cooling water supply start command or stop command is issued until the cooling water supply actually starts or stops on the steel plate is extremely shortened, Unnecessary cooling water can be avoided and the controllability of steel sheet cooling can be greatly improved. As a result, the steel sheet can be uniformly and stably water-cooled at a high cooling rate, the occurrence of material defects due to temperature unevenness in the longitudinal direction of the steel sheet is prevented, the material is less displaced, and the quality is high. Steel sheets can be manufactured.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic explanatory view showing a steel plate cooling device according to an embodiment of the present invention, and FIG. 1 is a view (side view) seen from the width direction of a steel plate (not shown).

  As shown in FIG. 1, the steel sheet cooling device according to one embodiment of the present invention is arranged in the vicinity of the steel sheet so as to be able to inject cooling water onto the upper surface of the steel sheet (not shown). A nozzle header 1 connected to a supply source (not shown) via a cooling water supply pipe 6, a cooling water supply control means 7 provided in the cooling water supply pipe 6, and a cooling water supply control means 7 are operated ( It has a basic structure comprising a cooling water supply control mechanism 8 for opening operation and closing operation) and a nozzle (nozzle group) 5 attached to the nozzle header 1.

  The nozzle header 1 is composed of an outer frame (outer tube) 2 having a rectangular cross section and an inner frame (inner tube) 3 having a circular cross section disposed on the inner side thereof, between the outer frame 2 and the inner frame 3. A space 4 is formed. Further, a plurality of through holes 3 a leading to the space 4 are provided in the upper part of the inner frame 3, and the cooling water supply pipe 6 passes through the outer frame 2 and is connected to the inner frame 3.

  The cooling water supply control means 7 is composed of an on-off valve (for example, an electromagnetic valve) that opens and closes by an electric signal, and sends an electric signal to the cooling water supply control mechanism (for example, a solenoid coil) 8 for cooling. When the water supply control means (cooling water supply opening / closing valve) 7 is opened, the cooling water from the cooling water supply source is supplied to the inner frame 3 of the nozzle header 1 through the cooling water supply pipe 6. The cooling water supplied into the inner frame 3 in this way is supplied into the space 4 through the through hole 3a formed in the upper portion thereof, and is ejected from the outlet of the nozzle 5 with uniform pressure. As a result, the steel sheet is cooled. Of course, if an electric signal is sent to the cooling water supply control mechanism 8 and the cooling water supply control means (cooling water supply opening / closing valve) 7 is closed, the supply of the cooling water into the nozzle header 1 is cut off.

  However, in the case of only the above-described basic structure, the cooling water in the cooling water supply pipe 6 a between the cooling water supply opening / closing valve 7 and the inner frame 3 is caused by the inner diameter and length of the cooling water supply pipe 6. Even if the cooling water supply on / off valve 7 is closed and the cooling water supply is stopped, the cooling water remaining in the cooling water supply pipe 6a and the nozzle header 1 moves downward due to gravity, and the nozzle 5 is discharged to the upper surface of the steel plate. Therefore, the cooling water stop delay time is long. In addition, when the cooling water is injected again, the cooling water supply pipe 6a and the nozzle header 1 need to be filled with the cooling water, so that the cooling water start delay time is long.

  Therefore, the steel sheet cooling apparatus according to this embodiment includes the cooling water blocking mechanism 9 configured to seal the cooling water remaining in the cooling water supply pipe 6a and the like in the nozzle header 1 as described above. . The cooling water shut-off mechanism 9 is composed of a shut-off valve that operates by pressure (shut-off operation and open operation), and is incorporated in the nozzle 5.

  The cooling water shut-off mechanism 9 includes, for example, a check valve mechanism for ON / OFF control of the descaling nozzle and a mechanism similar to a general check valve. May be used, and when the supply of cooling water is stopped, a water leakage prevention mechanism that closes the valve due to a decrease in water pressure may be used.

  An example of a cooling water blocking mechanism using such a water leakage prevention mechanism will be described with reference to FIG. This figure is a cross-sectional view showing a water leakage prevention mechanism (cooling water blocking mechanism) 9 integrally connected to the upstream side of the nozzle 5 having the injection holes 5a by screwing or the like. This water leakage prevention mechanism (cooling water shut-off mechanism) 9 has a structure in which a valve seat 9b, a valve body 9c, a balance spring 9d, and a spring support (spring seat) 9e are incorporated in this order from the upstream side inside a cylindrical body 9a. It has become. Then, by adjusting the position of the spring support 9e or the spring force of the balance spring 9d, the valve body 9c is pressed against the valve seat 9b when the water pressure acting from the upper side of the figure falls below a predetermined value (cut-off upper limit pressure). If the water flow is interrupted and a water pressure (water pressure exceeding the upper cutoff pressure) is applied to overcome the spring force of the balance spring 9d, the valve body 9c moves away from the valve seat 9b and water flows. Of course, when the cooling water supply control means (cooling water supply opening / closing valve) 7 is opened and cooling water is supplied into the cooling water supply pipe 6a and the nozzle header 1, the cooling water blocking mechanism 9 is also opened. Set the shut-off upper limit pressure so that.

  As a result, when the cooling water supply control means (cooling water supply opening / closing valve) 7 is opened, the cooling water blocking mechanism 9 is opened by applying a water pressure exceeding the blocking upper limit pressure to the cooling water blocking mechanism 9. Then, when the cooling water is injected from the nozzle 5 and the cooling water supply control means (cooling water supply opening / closing valve) 7 is closed, the cooling water blocking mechanism 9 can be applied with a water pressure equal to or lower than the cutoff upper limit pressure. For example, the cooling water blocking mechanism 9 performs a blocking operation, and the injection of the cooling water from the nozzle 5 stops while the remaining cooling water is held in the nozzle header 1 or the cooling water supply pipe 6a.

  The cooling water blocking mechanism 9 may be a mechanism that is electrically or mechanically turned on and off.

  Further, in the steel sheet cooling apparatus according to this embodiment, a cooling water discharge piping system (cooling) for instantaneously reducing the pressure of the cooling water remaining in the cooling water supply pipe 6a and the nozzle header 1 as described above. Water discharge mechanism).

  The cooling water discharge pipe system (cooling water discharge mechanism) has one end connected to the inner pipe 3 of the nozzle header 1 and the other end extending outside the steel plate existence area, and the cooling water discharge pipe 11. A cooling water discharge control means (for example, a solenoid valve) 12 provided on the cooling water, and a cooling water discharge control mechanism (for example, a solenoid coil) 13 for operating (opening operation, closing operation) the cooling water discharge control means 12. It is configured.

  The cooling water discharge control mechanism 13 is electrically connected to the cooling water supply control mechanism 8 and constitutes a control device as a unit. Thereby, the cooling water discharge control means (cooling water discharge on-off valve) 12 is closed when the cooling water supply control means (cooling water supply on-off valve) 7 is opened, and the cooling water supply control means (cooling water supply on-off valve). When the water supply on / off valve 7 is closed, it is opened.

  Thereby, when the cooling water supply control means 7 is closed by the cooling water supply stop command, the cooling water discharge control means 12 is opened at the same time, and the cooling water remaining in the cooling water supply pipe 6a and the nozzle header 1 is cooled. The water pressure discharged to the outside of the existing area of the steel sheet via the water discharge pipe 11 and acting on the cooling water blocking mechanism 9 is instantaneously reduced.

  Note that an air vent valve that is closed when the cooling water supply on / off valve 7 is opened and opened when the cooling water supply on / off valve 7 is closed is located downstream of the cooling water supply on / off valve 7 and It is preferable to provide upstream of the cooling water shut-off mechanism 9 because the cooling water discharge through the cooling water discharge pipe 11 after the cooling water supply opening / closing valve 7 is closed is promoted.

  Although details will be described later, as shown in FIG. 1, a pressure sensor 14 that is electrically connected to the cooling water discharge control mechanism 13 and detects the water pressure acting on the cooling water blocking mechanism 9 is installed. If the detected value of the pressure sensor 14 is equal to or lower than the shut-off upper limit pressure of the cooling water shut-off mechanism 9, the cooling water discharge control means 12 is closed by an instruction from the cooling water discharge control mechanism 13, so that the water cooling start characteristic is achieved. Can be improved.

  Next, the operation of the steel sheet cooling device according to this embodiment will be described below.

  First, when cooling water is supplied onto the surface of the steel plate in order to cool the steel plate, an electric signal (cooling water supply start command) is sent to the cooling water supply control mechanism 8 to open and close the cooling water supply on / off valve. 7 is released. Simultaneously or prior thereto, an electrical signal is sent to the cooling water discharge control mechanism 13 to close the cooling water discharge on-off valve 12. Thereby, the cooling water from the cooling water supply source passes through the cooling water supply pipe 6 and is supplied to the inner frame 3 of the nozzle header 1, and the cooling water supplied into the inner frame 3 passes through the through hole 3 a. After being supplied into the space 4, the cooling water blocking mechanism 9 is ejected from the nozzle 5 that is open at a uniform pressure, thereby cooling the entire surface of the steel plate.

  Next, in order to control cooling at the front and rear ends of the steel plate, when stopping the supply of cooling water on the surface of the steel plate, an electric signal (cooling water supply stop command) is sent to the cooling water supply control mechanism 8. Then, the on-off valve 7 for cooling water supply is closed. At the same time, an electrical signal is sent to the cooling water discharge control mechanism 13 to open the cooling water discharge on-off valve 12. As a result, the cooling water remaining in the cooling water supply pipe 6a and the nozzle header 1 is discharged via the cooling water discharge pipe 11, and the pressure in the nozzle header 1 (pressure acting on the cooling water blocking mechanism 9) is increased. The cooling water shut-off mechanism 9 instantaneously drops below the shut-off upper limit pressure and shuts off, and the remaining cooling water is blocked from being ejected from the nozzle 5, and cooling water dripping is quickly eliminated.

  Even when the cooling water shut-off mechanism 9 performs the shut-off operation, the cooling water discharge opening / closing valve 12 remains open, so that the cooling water discharge pipe 11 and the cooling water supply pipe 6a and the inner frame 3 of the nozzle header 1 can be used. However, the cooling water remains in the space 4 up to the height of the through hole 3a.

  Thus, in the steel sheet cooling apparatus according to this embodiment, the time from when the cooling water supply stop command is issued until the cooling water supply actually stops on the steel sheet (cooling water stop delay time). Is extremely shortened, and unnecessary cooling water is prevented from being poured out from the nozzle outlet 5a, so that excellent water cooling stop characteristics (off characteristics) are obtained, and the controllability of cooling of the steel sheet can be greatly improved.

  Further, even when the supply of the cooling water onto the steel plate is started (restarted), the remaining cooling water is already filled in the space 4 up to the height position of the through hole 3a. It takes less time to fill the supply pipe 6a and the nozzle header 1 with the cooling water, and after issuing the cooling water supply start command, the time that the cooling water is actually ejected from the nozzle 5 (cooling water supply start delay time) is Shorter and good water cooling start characteristics (ON characteristics) can be obtained.

  As a result, the steel sheet can be uniformly and stably water-cooled at a high cooling rate, the occurrence of material defects due to temperature unevenness in the longitudinal direction of the steel sheet is prevented, the material is less displaced, and the quality is high. Steel sheets can be manufactured.

  Furthermore, as described above, the pressure sensor 14 that is electrically connected to the cooling water discharge control mechanism 13 and detects the water pressure acting on the cooling water blocking mechanism 9 is installed, and the detected value of the pressure sensor 14 is When the cooling water shut-off mechanism 9 is below the shut-off upper limit pressure, the cooling water discharge control means 12 is controlled to be closed by the instruction from the coolant discharge control mechanism 13 so that the cooling water discharge control means 12 is closed. If it carries out, a water-cooling start characteristic can be improved further.

  That is, when the cooling water supply control means 7 is closed by the cooling water supply stop command, the cooling water discharge control means 12 is opened while the water pressure acting on the cooling water cutoff mechanism 9 exceeds the cutoff upper limit pressure. Then, the remaining cooling water is discharged via the cooling water discharge pipe 11, but if the pressure detected by the pressure sensor 14 (water pressure acting on the cooling water blocking mechanism 9) becomes equal to or lower than the cutoff upper limit pressure, Since the shut-off mechanism 9 performs the shut-off operation and the coolant discharge control means 12 is closed by an instruction from the coolant discharge control mechanism 13, the remaining cooling water in the amount corresponding to the shut-off upper limit pressure is retained in the nozzle header 1 or the cooling. It is held in the water supply pipe 6a. Therefore, when the supply of the cooling water onto the steel sheet is started (restarted), the remaining amount of the cooling water corresponding to the shut-off upper limit pressure is already held, and accordingly, the cooling water supply pipe 6a and It takes less time to fill the nozzle header 1 with cooling water, and after issuing the cooling water supply start command, the time that the cooling water is actually ejected from the nozzle 5 (cooling water supply start delay time) becomes very short, Better water cooling start characteristics (ON characteristics) can be obtained.

  As a result, the steel sheet can be uniformly and stably water-cooled at a high cooling rate, the occurrence of material defects due to temperature unevenness in the longitudinal direction of the steel sheet is prevented, the material deviation is reduced, and the quality is further improved. High steel sheets can be manufactured.

  Incidentally, the pressure sensor 14 is preferably installed in the immediate vicinity of the cooling water blocking mechanism 9, but in some cases, the pressure sensor 14 is installed at a position slightly away from the cooling water blocking mechanism 9, and the pressure difference of the pressure sensor 14 is set with the water head difference as a bias. It may be added to the actual measurement value.

  If the cooling water discharge opening / closing valve 7 has a large diameter and takes a long time to operate, control may be performed to open the cooling water discharge opening / closing valve 12 prior to the cooling water supply stop command. .

  And when installing the above cooling apparatuses in the hot rolling line of a steel plate, what is necessary is just to arrange | position and arrange a desired number of cooling devices in the steel plate conveyance direction.

  Moreover, the injection direction of the cooling water is not limited to the case of injecting vertically downward as in the present embodiment, and may be injecting obliquely downward, for example.

  Example 1 of the present invention will be described below.

  As Example 1 of this invention, it decided to cool the hot-rolled steel plate online using the cooling equipment containing the cooling device of the steel plate which concerns on said embodiment. Here, nine sets of this cooling device are arranged side by side in the steel plate conveyance direction to cool the upper surface of the thick steel plate. For cooling the lower surface of the thick steel plate, a cooling device having a general laminar nozzle having a cooling capacity equivalent to that of the upper surface was used.

  As a cooling water supply control means (cooling water supply opening / closing valve) 7 in each cooling device, an electromagnetic valve having one inlet port and three outlet ports is used, and the inlet port is connected to a cooling water supply source. Three outlet ports were connected to the inner frame 3 of the nozzle header 1 via three cooling water supply pipes 6.

  The width of the nozzle header 1 is 5 m, the outer frame 2 is 400 mm square, the inner frame 3 has an inner diameter of 200 mm, the nozzle outlet 5a has a diameter of 6 mm, and the amount of cooling water supplied is 1000 liters / minute (± 50 Liter / min).

  First, the water cooling stop characteristic (off characteristic) of this cooling device was confirmed. That is, a required time (cooling water stop delay time) from when the cooling water supply stop command is issued and the cooling water supply opening / closing valve 7 is closed until the cooling water supply from the nozzle 5 is completely stopped was investigated. . Next, in order to confirm the water cooling start characteristic (ON characteristic), a cooling water supply start command is issued, the cooling water supply opening / closing valve 7 is opened, and then the cooling water is uniformly injected from the cooling device. The time (cooling water start delay time) was investigated.

  At this time, in the first example of the present invention, the cooling water blocking mechanism 9 is provided in the nozzle 5, and the cooling water discharge mechanism (cooling water discharge pipe 11, cooling water discharge control means 12, cooling water discharge control mechanism is provided in the nozzle header inner pipe 3. 13) was provided.

  Further, in the present invention example 2, in addition to the present invention example 1, the pressure sensor 14 for detecting the pressure acting on the cooling water blocking mechanism 9 is provided, and the closing control of the cooling water discharge control means 12 is performed.

  On the other hand, in Comparative Example 1, the cooling water blocking mechanism 9 and the cooling water discharge mechanism were not provided.

  In Comparative Example 2, the nozzle 5 was provided with the cooling water blocking mechanism 9 and the outer pipe 2 was provided with the cooling water discharge mechanism.

  As a result, in Example 1 of the present invention, in order to stop the supply of the cooling water on the steel plate, an electric signal (cooling water supply stop command) is sent to the cooling water supply control mechanism 8 and the on / off valve 7 for supplying the cooling water is supplied. Is closed, the cooling water discharge opening / closing valve 12 is opened, water is discharged from the cooling water discharge pipe 11, and when the water pressure acting on the cooling water blocking mechanism 9 becomes equal to or lower than the blocking upper limit pressure, the cooling water blocking mechanism 9 The shutoff operation was performed, and the supply of cooling water from the nozzle 5 was completely stopped. The cooling water stop delay time at that time was very short, about 0.8 seconds. Further, the time from when the cooling water supply start command is stably supplied to the cooling water from the nozzle 5 (cooling water start delay time) is because the remaining cooling water is already filled in the nozzle header outer pipe 2. It was as short as 5 seconds.

In the present invention example 2, when the cooling water supply on / off valve 7 is closed by sending an electric signal (cooling water supply stop command) to the cooling water supply control mechanism 13 in order to stop the supply of the cooling water on the steel plate. When the cooling water discharge opening / closing valve 12 is opened, water is discharged from the cooling water discharge pipe 11, and the detected value of the pressure sensor 14 becomes equal to or lower than the cutoff upper limit pressure of the cooling water cutoff mechanism 9, the cooling water discharge opening / closing valve 12 was closed, drainage from the cooling water discharge pipe 11 was stopped, and the cooling water shut-off mechanism 9 was shut off, and the supply of cooling water from the nozzle 5 was completely stopped. The cooling water stop delay time at that time was very short, about 0.8 seconds. In addition, from the cooling water supply start command until the cooling water is stably supplied from the nozzle 5 (cooling water start delay time), the remaining amount of cooling water corresponding to the shut-off upper limit pressure is already held. Therefore, on the other hand, in Comparative Example 1, in order to stop the supply of the cooling water on the steel plate, an electric signal (cooling water supply stop command) was sent to the cooling water supply control mechanism 7 in Comparative Example 1, When the cooling water supply opening / closing valve 7 is closed, the cooling water remaining in the cooling water supply pipe 6a and in the space 4 is slowly discharged from the nozzle 5, and then the cooling water supply to the steel plate is completely stopped. did. At that time, the cooling water supply stop delay time was very long, about 30 seconds. In addition, regarding the cooling water supply start delay time, since all the cooling water remaining in the cooling water supply pipe 6a and the space 4 has been discharged, the cooling water is newly circulated in the cooling water supply pipe 6a and the nozzle header 1. The cooling water from the cooling water supply source passes through the cooling water supply pipe 6a and is supplied to the inner frame 3 of the nozzle header 1, and the cooling water supplied into the inner frame 3 passes through the through hole 3a. After being supplied into the space 4 and passing through the nozzle 5, the cooling water supply start delay time was as long as 12 seconds.

  In Comparative Example 2, since the cooling water shut-off mechanism 9 and the cooling water discharge mechanism are provided, the cooling water supply stop delay time is as short as about 0.8 seconds. Since the mechanism is provided in the outer tube 2, the remaining cooling water is hardly held in the nozzle header 1, and as a result, it is as long as 12 seconds as in the case of Comparative Example 1.

  When the air vent valve is made to function, the water cooling stop characteristic is slightly improved as compared with the case where the air vent valve is not made to function, and the cooling water stop delay time when the air vent valve is made to function in Example 1 of the present invention is about 0. It became very short with 5 seconds.

  The survey results of the water cooling stop characteristics and the water cooling start characteristics are organized and shown in Table 1.

  Next, as described above, using a cooling facility including nine sets of steel plate cooling devices according to the above-described embodiment, the steel plate after hot rolling was cooled online while passing through.

  The dimensions of the thick steel plate were a plate width of 4300 mm, a plate length of 18 m, a plate thickness of 32 mm, and a conveying speed of 20 mpm. When the temperature in the longitudinal direction of the thick steel plate when passing through the cooling equipment entrance side, that is, the temperature of the thick steel plate before water cooling was measured, it was 840 ° C. near the front end of the thick steel plate, 770 ° C. near the rear end, and about 70 at the front and rear end. There was a temperature difference of ° C.

  Then, among the 9 sets of cooling devices, in the subsequent 3 sets of cooling devices, the cooling water supply opening / closing of each cooling device at the timing when the portion corresponding to the position of 1.5 m from the rear end of the thick steel plate passes. The valve 7 was closed, and the temperature in the longitudinal direction of the thick steel plate when passing through the cooling facility exit side, that is, the temperature of the thick steel plate after water cooling was measured.

  At that time, each of the three cooling devices in the rear stage was compared in the case of the present invention example 1 and the present invention example 2 and in the case of the comparative example 1 and the comparative example 2.

  As a result, when the cooling devices of the subsequent three sets were in the states of Invention Examples 1 and 2 and Comparative Example 2, the temperature difference between the front and rear ends of the thick steel plate that was 70 ° C. before water cooling was Each decreased to about 20 ° C. And although the thick steel plate cooled in this way was cooled to normal temperature with the cooling floor, distortion, such as curvature, did not generate | occur | produce at all. Further, the hardness in the longitudinal direction of the thick steel plate was measured, but it had a uniform hardness distribution and the variation in material was very small. Therefore, there was no downgrade of the end of the thick steel plate due to the deviation of the material, and the product yield was 100%.

  On the other hand, when each of the rear three sets of cooling devices is in the state of Comparative Example 1, the temperature difference between the front and rear ends of the thick steel plate, which was 70 ° C. before water cooling, is not much changed to about 60 ° C. even after water cooling. It was. This is probably because the water cooling stop delay time was about 30 seconds, and thus the cooling water was dropped on the rear end of the thick steel plate even after the cooling water supply stop command. And when the thick steel plate cooled in this way was cooled to normal temperature with the cooling floor, distortion, such as curvature, had generate | occur | produced. Moreover, when the hardness in the longitudinal direction of the thick steel plate was measured, there was a portion with high hardness due to uneven cooling, and the material variation was large. As a result, the deterioration of the thick steel plate end due to the deviation of the material was 0.56 m, and the product yield was 97%.

  In addition, regarding the cooling start characteristics, since the cooling start characteristics were grasped in advance, the water cooling control was performed by changing the issuing time of the cooling water supply start command, so the product yield was not affected. In Comparative Examples 1 and 2, the time during which water was jetted in the absence of the steel sheet was compared. As compared with Invention Example 2, Invention Example 1 was tripled and Comparative Examples 1 and 2 were 10 times as much. Cooling water was wasted and uneconomical, and the running cost was proportional to the cooling water injection time and increased.

It is a schematic explanatory drawing (side view) of one Embodiment of this invention. It is sectional drawing of an example of the cooling water interruption | blocking mechanism in one Embodiment of this invention.

Explanation of symbols

1 Nozzle header 2 Outer frame (outer tube)
3 inner frame (inner pipe)
3a Through-hole 4 Space 5 Nozzle (nozzle group)
5a Nozzle injection hole 6 Cooling water supply pipe 6a Cooling water supply pipe between the cooling water supply on-off valve and the inner frame 7 Cooling water supply control means (cooling water supply on-off valve, solenoid valve, etc.)
8 Cooling water supply control mechanism (solenoid coil, etc.)
DESCRIPTION OF SYMBOLS 9 Cooling water shut-off mechanism 9a Tubular body 9b Valve seat 9c Valve body 9d Balance spring 9e Spring support 11 Cooling water discharge pipe 12 Cooling water discharge control means (cooling water discharge on-off valve, solenoid valve, etc.)
13 Cooling water discharge control mechanism (solenoid coil, etc.)
14 Pressure sensor

Claims (4)

A nozzle header disposed in the vicinity of the steel plate and connected to a cooling water supply source via a cooling water supply pipe, a cooling water supply control means provided in the cooling water supply pipe, and a nozzle attached to the nozzle header In a steel sheet cooling device comprising:
The nozzle header includes an outer tube and an inner tube that is disposed inside the outer tube so as to form a space between the outer tube and has a through hole in an upper portion, and is one end of the cooling water supply tube. Is connected to the inner pipe through the outer pipe of the nozzle header,
The nozzle has a cooling water shut-off mechanism that operates by pressure, and is connected to the inner pipe and discharges the cooling water from the nozzle header to the outside of the area where the steel sheet exists, and the cooling water discharge pipe A cooling apparatus for a steel sheet, comprising a cooling water discharge control means provided.   The steel sheet cooling apparatus according to claim 1, further comprising pressure detecting means for detecting a water pressure acting on the cooling water blocking mechanism. A method for cooling a steel sheet using the cooling device according to claim 1,
When starting the supply of the cooling water onto the steel plate, the cooling water supply control means is opened, and at the same time or in advance, the cooling water discharge control means is closed to act on the cooling water blocking mechanism. When the water pressure exceeds a predetermined pressure, the cooling water shut-off mechanism takes the opening action, and the cooling water is ejected from the nozzle,
When stopping the supply of the cooling water on the steel plate, the cooling water supply control means is closed and at the same time the cooling water discharge control means is opened so that the pressure acting on the cooling water shut-off mechanism is a predetermined pressure. A cooling method for a steel sheet, characterized in that when the pressure falls below the pressure, the cooling water shut-off mechanism takes a shut-off action to shut off the cooling water from the nozzle. A method for cooling a steel sheet using the cooling device according to claim 2,
When starting the supply of the cooling water onto the steel plate, the cooling water supply control means is opened, and at the same time or in advance, the cooling water discharge control means is closed to act on the cooling water blocking mechanism. When the water pressure exceeds a predetermined pressure, the cooling water shut-off mechanism takes the opening action, and the cooling water is ejected from the nozzle,
When stopping the supply of the cooling water on the steel plate, the cooling water supply control means is closed and at the same time the cooling water discharge control means is opened so that the pressure acting on the cooling water shut-off mechanism is a predetermined pressure. When the pressure falls below the pressure, the cooling water shut-off mechanism takes a shut-off action to shut off the cooling water from the nozzle, and when the detected value of the pressure detecting means falls below a predetermined pressure, the cooling water discharge control means A method for cooling a steel sheet, characterized in that a closing operation is performed.

Images