JPS61153236A - Equipment for on-line cooling steel of plate - Google Patents

Abstract

PURPOSE:To prevent the formation of an ununiform structure and to reduce the cost of equipment by installing a primary cooling apparatus in which a hot rolled steel plate is cooled in a restrained state and a secondary cooling apparatus in which the steel plate is cooled in a nonrestrained state so as to enable uniform cooling and reduction in the size of equipment. CONSTITUTION:A hot rolled steel plate is transferred into a primary cooling apparatus 5 on a line with table rolls 9. An upper pressing roll 19, an upper wringer roll 28 and an upper slit jet nozzle 20 are lowered to restrain the steel plate, and the upper and under sides of the steel plate are cooled with cooling water from slit nozzles 20, 21. The steel plate is then transferred into a secondary cooling apparatus, where the upper and under sides of the steel plate are cooled with cooling water from pipe nozzles 36, 58 and cooling water from spray nozzles 46, 59, respectively.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to direct quenching of thick steel plates.
Regarding online cooling equipment for thick steel plates in Q), etc.

(Problems to be solved by the prior art and the invention) When performing controlled cooling or direct quenching of thick steel plates, especially direct quenching, a high cooling capacity is required, so a large flow rate of cooling water is required. .

The equipment for directly quenching as described above is the Tokko Kokko 1977. -46641 Publication, Special Publication No. 56-49974
JP-A No. 57-92141, etc. are known.

In these cooling equipment, the steel plate is restrained between a lower presser roller that also serves as a table roller for conveying the thick steel plate, and an upper presser roller that pairs with the lower roller, and the steel plate is cooled from a cooling nozzle installed between the rollers. The thick steel plate is cooled by the cooling water flow.

By the way, since the conventional cooling equipment described above is an online cooling equipment, the equipment above the thick steel plate, such as the presser foot upper roller and the cooling nozzle, must be raised and lowered by a large distance, or a mechanism that can take the thick steel plate off the line must be installed. In order to prepare for this, it was necessary to separately install a table roller, which increased the size of the equipment.
There are problems in that maintenance becomes difficult and equipment costs increase.

Therefore, in order to solve this problem, Japanese Patent Application Laid-Open No. 58-3916 was developed as a cooling equipment that cools thick steel plates without restraint.
The method shown in the above publication has already been proposed.

However, with the above cooling method, there is a large difference in the cooling capacity of the thick steel plate between directly below the cooling nozzle and other areas, so the temperature history of the thick steel plate repeats large amplitudes, causing unevenness on the thick steel plate. Organization arises and becomes a problem.

An object of the present invention is to provide an online cooling facility that can prevent uneven structures from forming in thick steel plates, reduce the size of the cooling facility, facilitate maintenance, and reduce equipment costs. do.

(Means for solving the problems) In order to achieve the above object, the features of the present invention are as follows:
a primary cooling device 5 that cools the thick steel plate 4 while restraining it;
A secondary cooling device 6 that cools the thick steel plate 4 without restraint is arranged in the above order in the sheet passing direction, and the primary cooling device 5 cooperates with the table roller 9 to reduce the thickness m@ 4, slit jet nozzles 20 and 21 provided above and below the pass line 7 of the thick steel plate 4 to cool the upper and lower surfaces of the thick steel plate 4 with a cooling water flow, and the table roller 9 cooperate with each other. and the draining upper roller 28 which holds the thick steel plate 4 from above and below and prevents the cooling water from the slit jet nozzle 20.21 from flowing out to the secondary cooling device 6 side. By raising and lowering the presser foot upper roller 19, draining upper roller 28, and upper slit jet nozzle 20, each of these rollers 19.
The thick steel plate 4 is releasably restrained or held by the table roller 9 and the upper slit jet nozzle 20.
The secondary cooling device 6 includes a pipe nozzle 36.58 that cools the upper surface of the thick steel plate 4 with a cooling water flow, and a lower surface of the thick steel plate 4. It is equipped with a spray nozzle 46.59 for cooling with a cooling water flow.

(Function) According to the present invention, the thick steel plate 4 immediately after hot rolling is conveyed online by the table rollers 9 and carried into the primary cooling device 5.

At this time, the presser foot upper roller 19, draining upper roller 28, and upper slit jet nozzle 20 are in the raised position, but when the thick steel plate 4 is carried in as described above, the presser foot upper roller 19
The upper draining roller 28 and the upper slit jet nozzle 20 are lowered by the lifting mechanism 13, the thick steel plate 4 is restrained by the upper presser foot roller 19 and the table roller 19, and the upper slit jet nozzle 20 is in the cooling work position. .

In the above state, in the primary cooling device 5, the upper and lower surfaces of the thick steel plate 4 are cooled by the cooling water flow from the slit jet nozzles 20, 21.

Then, the thick steel plate 4 is further conveyed by table rollers 9 and carried into the secondary cooling device 6, where the upper surface of the thick steel plate 4 is cooled by the cooling water flow from the pipe nozzle 36.58, and the lower surface is cooled by the cooling water flow from the spray nozzle 46.59. Each is cooled by a cooling water flow.

In this case, the thick steel plate 4 is held between the upper and lower draining rollers 28 and the table rollers 9 to prevent the cooling water from the slit jet nozzles 20 and 21 from flowing out to the secondary cooling device 6 side. be done.

(Embodiment) Hereinafter, the first embodiment of the present invention will be explained based on the drawings of Figs. 1 to 13. Fig. 2 shows an outline of an example of equipment layout, and ■ is a finishing rolling mill; On-line cooling equipment 2 and bot leveler 3 are arranged in the above order in front of the plate passing direction, and the thick steel plate 4 is passed through each of the above-mentioned equipment. Note that, as shown by the imaginary line in FIG. 2, the cooling equipment 2 may be arranged in front of the hot leveler 3 in the sheet passing direction.

The cooling method using the cooling equipment 2 is such that while the thick steel plate 4 is being transported,
This is a one-way plate cooling method in which the plate is sequentially cooled from the front end to the rear end in the conveying direction. This type of cooling method is
This is because the above method requires the least amount of water when considering the cooling capacity required for direct quenching. For example, in a cooling method using an oscillating resin threading method in which a thick steel plate is cooled while being reciprocated, a cooling area that is longer than the length of the thick steel plate is required. Further, even in a cooling method using unidirectional threading in which the entire surface of a thick steel plate is cooled simultaneously, a cooling area that is longer than the length of the thick steel plate is required.

As shown in FIGS. 1 and 3, in the cooling equipment 2, a primary cooling device 5 and a secondary cooling device 6 are installed in parallel in the above order in the sheet passing direction, and each Below the pass line 7 of the device 5.6, a large number of table rollers 9 for conveying the thick steel plate 4 are arranged in parallel in the sheet passing direction.

The primary cooling device 5 strongly cools the thick steel plate 4 while restraining it, and includes a main fixed frame 11, a vertical lifting frame 12, 16, a screw jack 13, an upper presser roller 19, and an upper and lower slit. jet nozzle 20.21,
It is equipped with upper and lower cooling water discharge troughs 26, 27, an upper draining roller 28, a protector guide 30, and the like.

The main fixed frame 11 is located above the pass line 7, and the frame 11 is equipped with an elevating frame 12 that can be raised and lowered by an elevating screw jack 13. The jack 13 is driven by an electric motor via a transmission mechanism 14.

A plurality of guide shafts 15 are lowered from the lift frame 12, and lower lift frames 16 are provided on these guide shafts 15 so as to be able to rise and fall freely, and lower lift frames 16 are provided at the upper and lower ends of each guide shaft 15, respectively. Or ammunition 1 that urges upward
7.18 is interposed in a spring-like manner, and the lowering/elevating frame 16 is in a floating state.

The presser foot upper roller 19 is provided on the front side of the lower elevating frame 16, and is vertically opposed to one table roller 9 serving as a presser foot lower roller.
．． 16 is lowered, the thick steel plate 4 is releasably restrained in cooperation with the table roller 9.

The upper slit jet nozzle 2o is connected to the lower elevating frame 16.
The lower slit jet nozzle 21 is disposed between the table rollers 9 and vertically opposed to the upper slit jet nozzle 20.
The upper and lower surfaces of the unit are cooled by a cooling water flow.

The opening at the tip of each slit jet nozzle 20.21 is
The thick steel plate 4 has a horizontally elongated shape that spans at least the entire length in the width direction, so that the thick steel plate 4 is not locally cooled in the width direction.

Each slit jet nozzle 20.21 has a pass line 7
is oriented from above and below, but it is inclined with respect to the vertical direction so as to move toward the front side in the sheet passing direction toward the tip.

This is because (i) the cooling water from the upper slit jet nozzle 20 is prevented from flowing to the rear side of the nozzle 20 on the thick steel plate 4, and thereby the slit jet nozzle 20.2
In order to prevent the thick steel plate 4 from being cooled slowly by the cooling water flowing from the nozzle 20 to the rear side in the sheet passing direction before the strong cooling in step 1, the temperature decreases and the material quality deteriorates. (ii ) If the slit jet nozzles 20 and 21 are oriented at right angles to the pass line 7, the cooling water will splash a lot after hitting the thick steel plate 4, resulting in a low cooling efficiency, so this is to prevent this. .

The upper slit jet nozzle 20 is connected to the upper cooling water main pipe 23 via the upper cooling water pipe 22, and the lower slit jet nozzle 21 is connected to the lower cooling water pipe 24.

The upper slit jet nozzle 20 is connected to the vertical lifting frame 12
．． 16, the non-cooled working position shown in FIG.
It is said that the position can be freely changed to the cooling work position below.

Note that a ball joint 25 is interposed in the upper cooling water pipe 22 in order to accommodate the raising and lowering of the upper slit jet nozzle 20.

The upper cooling water discharge gutter 26 is disposed in front of the upper slit jet nozzle 20 of the lower elevating frame 16 in the sheet passing direction, and
- Quickly drain the cooling water flowing on the upper surface of the steel plate 4.

The lower cooling water discharge gutter 27 is arranged on the front side of the lower slit jet nozzle 21 in the sheet passing direction, and quickly discharges the cooling water flowing on the lower surface side of the thick steel plate 4.

The upper draining roller 28 is provided at the rear of the lower elevating frame 16, and vertically faces the 1llil table roller 9, which serves as the lower draining roller, and releasably clamps the thick steel plate 4, so that the slit jet nozzle 20° 21 from flowing out to the secondary cooling device 6 side,
This prevents the cooling water from the slit jet nozzles 20 and 21 from disturbing the cooling by the secondary cooling device 6.

Note that the presser foot upper roller 19 and the drainer upper roller 28 are driven by an electric motor 29, and each roller 19.degree. 28 is in a restraining or clamping position at the position shown by the imaginary line in FIG.
The position shown by the solid line in FIG. 1 is the release position, and in the restraint or clamping position, each roller 19.2B is pressed against the thick steel plate 4 with a predetermined pressing force.

The protector guide 30 is provided at the front of the lowering/elevating frame 16 and protects the presser foot upper roller 19 and the like from the thick steel plate 4.

Incidentally, the elevating body 31 is composed of the vertically elevating frame 12.16, the bullet machine 17.1B, the presser foot upper roller 19, the upper slit jet nozzle 20, the upper cooling water discharge gutter 26, the draining upper roller 28, the protector guide 30, etc. There is.

In addition, in response to deformation in the vertical direction of the thick steel plate 4, such as warping, the elevating body 31 moves up and down minutely due to deformation of the bullets 17 and 18.

The secondary cooling device 6 cools the thick steel plate 4 in an unrestricted state, and is made up of a front cooling device 33 on the front stage side and a rear cooling device 34 on the rear stage side.

Each cooling device 33,34 comprises a main fixed frame 35, a pipe nozzle ladder 37 with a pipe nozzle 36, a spray header 43 with a full cone spray nozzle 46, etc.

The main fixed frame 35 is located above the pass line 7,
A pipe nozzle 3 as shown in FIG. 4 is attached to the frame 35.
A pipe nozzle header 37 having a large number of pipe nozzles 6 is provided, and the pipe nozzles 36 cool the upper surface of the thick steel plate 4 with a flow of cooling water.

As shown in FIG. 5, the pipe nozzles 36 are arranged in a staggered manner, and the arrangement pitch in the width direction (al and the arrangement pitch (b) in the threading direction are both 100 f).
The arrangement pitch (a) is about l or less.
(b) is considered dense.

The reason why the pipe nozzle header 37 is of a box type as shown in FIG. 4 is because the hairpin pipe nozzle header shown in FIGS. 6 and 7 does not allow narrow spacing between the nozzles 39.

The pipe nozzle header 37 is connected to a main pipe 42 via an upper water pipe 40 and an upper main branch pipe 41.

The spray header 43 is arranged in the left-right direction between adjacent table rollers 9 and is connected to a lower main pipe 45 via a lower water pipe 44 .

As shown in FIG. 8, in each spray header 43, full cone spray nozzles 46 are densely arranged in a staggered manner, and the cooling water flow from each nozzle 46 is directed to the lower surface of the thick steel plate 4 within a predetermined cooling range 47. The air cooling recuperation area of the thick steel plate 4 near the table roller 9 is suppressed.

Note that it is also possible to increase the arrangement density of the spray nozzles 46 as long as space permits.

The distance between the spray nozzle 46 and the thick steel plate 4 during the cooling operation is generally about 50 mm.

In FIG. 8, the spray nozzles 46 indicated by .are oriented at right angles to the pass line 7, and the spray nozzles 46 indicated by 0 are oriented in the vertical direction so that they move forward or backward in the sheet passing direction as they move toward the tip. The angle of inclination is about 17 degrees.

In addition, if the nozzle arrangement is considered, it is also possible to use a different type of spray nozzle instead of the full cone type.

Next, the outline of cooling of the thick steel plate 4 by the cooling equipment 2 will be explained.

First, before cooling work, the first
The elevating body 31 of the secondary cooling device 5 is in the raised position as shown in FIGS. 1 and 3.

After or before the high-temperature thick steel plate 4 is carried into the primary cooling device 5, the elevating body 31 is lowered, and the presser foot upper roller 19 and the table roller 9 move the thick steel plate 4 is set to be constrained, and in this state,
The upper and lower surfaces of the thick steel plate 4 are strongly cooled by cooling water flow over the entire widthwise length of the thick steel plate 4 from the upper and lower slit jet nozzles 20 and 21 sequentially from the front end to the rear end in the threading direction, and the surface of the thick steel plate 4 is The temperature is significantly reduced.

By the way, in the above cooling method using the slit jet nozzle 20, 21, the thick steel plate 4 can be strongly cooled uniformly in the width direction and the threading direction, so that the temperature history of the thick steel plate 4 can be prevented from repeating large amplitudes, and the thickness can be reduced. It is possible to prevent the steel plate 4 from having a non-uniform structure, that is, from causing material unevenness.

Further, since the thick steel plate 4 is cooled while being restrained by the presser foot upper roller 19 and the table roller 9, the cooling area can be made stable, uniform cooling is possible, and the thickness that occurs during water cooling is reduced. Thermal deformation of the steel plate 4 is extremely small.

Then, the thick steel plate 4 is conveyed by the table roller 9, and is further transferred to the front and rear cooling devices 33, 34 of the secondary cooling device 6.
In this case, the upper and lower surfaces of the thick steel plate 4 are held between the draining upper roller 28 and the table roller 9 at the rear end of the primary cooling device 5. Therefore, the cooling water produced by the primary cooling device 5 is prevented from causing cooling disturbance caused by the secondary cooling device 6.

In each cooling device 33, 34 of the secondary cooling device 6, the upper and lower surfaces of the thick steel plate 4 are sequentially exposed from the pipe nozzle 36 and the full cone spray nozzle 46 from the front end to the rear end in the sheet passing direction. It is cooled by a cooling water flow.

Next, in order to investigate the adverse effects when the thick steel plate 4 is slowly cooled by the cooling water flowing from the nozzle 20.21 to the rear side in the sheet passing direction before strong cooling by the slit jet nozzle in the primary cooling device. An experiment was conducted under the following conditions.

Main chemical composition (weight %) of thick steel plate (steel type A) Size of thick steel plate: Thickness 22N9 Width 3,200 * Stamp.

Length 10,800+n Cooling stop temperature: 200℃ or less Upper hinge slit jet nozzle water volume: 3.5 rr
r/min ・m Water density of pipe nozzle: 1.5 n? /min −
♂Spray nozzle water density: 2. Onr/min −
rrr Tempering temperature: 650°C Through the above experiment, the relationship between the cooling start temperature when a thick steel plate is cooled by cooling water from a slit jet nozzle, tensile strength, and 0.2% proof stress is shown in Figure 9. The results shown are obtained.

If you look at Figure 9, if the temperature of the thick steel plate decreases before it is strongly cooled by the slit jet nozzle, it will lead to material deterioration (
This shows the effectiveness of tilting the slit jet nozzle.

By the way, cooling by the slit jet nozzle has an important meaning in terms of the material quality of the thick steel plate.

In other words, when cooling with a pipe nozzle in a secondary cooling system, there is a large difference between the cooling capacity directly below the nozzle and the cooling capacity elsewhere, so depending on operating conditions and equipment conditions, a non-uniform structure may occur in the thick steel plate. That will happen. Furthermore, the magnitude of the cooling capacity also affects whether or not a predetermined material of the thick steel plate can be obtained.

Therefore, an experiment was conducted under the following conditions.

Steel type: A Thickness of steel plate: 25+m Cooling start temperature: 850℃ or higher Cooling stop temperature: 150℃ or lower Upper hinge slit jet nozzle water volume: 1 to 4 nf
/min -m Pipe nozzle water density: 1.5%/min ・
d Spray nozzle water density: 2. Orrr/mtn
-rtf pipe nozzle pitch: 7511 in the width direction, 15011 in the threading direction Spray nozzle pitch: 100 x in the width direction, 1 in the threading direction
50+mi plover array tempering temperature: 650°C Steel plate conveyance speed: 0.4 to 1.2 m/s The steel plate conveyance speed is changed in order to change the entrance temperature of the secondary cooling device.

Figure 10 shows the experimental results in a graph, and shows how the material and strength of the thick steel plate are affected by the amount of cooling water in the slit jet nozzle and the surface temperature of the thick steel plate on the outlet side of the draining roll. It indicates whether you will receive it. Note that the surface temperature was estimated from a cooling curve obtained by cooling a thick steel plate in which thermocouples were embedded in advance.

According to FIG. 10, in order to secure the cooling capacity necessary to ensure the strength of the thick steel plate, the amount of cooling water in the slit jet nozzle needs to be 2rd/min -m or more,
It can be seen that in order to prevent material unevenness, the surface temperature of the thick steel plate must be 600° C. or lower on the exit side of the draining roll. Note that the occurrence of material unevenness differs depending on the steel type.

That is, there are some cases where the temperature may be higher than 600°C.

Incidentally, regarding the occurrence of material unevenness, the arrangement pitch of the pipe nozzles of the secondary cooling device also has an important influence.

That is, when the arrangement of the pipe nozzles becomes coarse, it becomes necessary to increase the amount of cooling water for the slit jet nozzles, and it becomes necessary to provide the slit jet nozzles in multiple stages.
The total amount of cooling water becomes enormous.

Moreover, if the arrangement pitch of the pipe nozzles is made denser, the number of pipe nozzles becomes enormous, which is the opposite of the above, which causes problems in equipment manufacturing.

Therefore, it is preferable that the arrangement pitch of the pipe nozzles is as shown in FIG.

Next, in order to investigate the relationship between the cooling stop temperature and the material unevenness in the thickness direction of the steel plate, an experiment was conducted under the following conditions.

Next Main chemical components (wt%) of thick steel plate (steel type B) Thick steel plate size: Thickness 30 Fin Cooling start temperature: 850'C or higher Cooling stop temperature: Room temperature to 400 °C Upper hinge slit jet nozzle Water amount: 3 rrr/
min -m Water density of pipe nozzle: 1.5 n? /min
-♂Spray nozzle water density: 2. Orr/min
- Popipe nozzle pitch: 75 m1 in the width direction, 150 mm in the threading direction Plover array spray nozzle pitch: 100' in the width direction *vb, 150 IIm in the threading direction Plover array steel plate conveying speed: 0.3 m/s No tempering, In order to change the cooling stop temperature, the cooling time of the secondary cooling device was changed.

Figure 11 shows the above experimental results, and it can be seen that in order to obtain a Vickers hardness close to the Vickers hardness of a thick steel plate when the cooling stop temperature is room temperature, the cooling stop temperature must be 200°C or less. .

Next, an experiment was conducted under the following conditions to investigate the relationship between the water density of the cooling water in the secondary cooling device and the tensile strength of the thick steel plate.

Steel type: A Thick steel plate size: 251m thick Cooling start temperature: 850℃ or higher Cooling stop temperature: 150℃ or lower Upper hinge slit jet nozzle water volume: 3 rrr/
min -m Average water density of secondary cooling device: 0.5 to 1.2 M/m
1n-rrr Pipe nozzle pitch: 75 in the width direction **, 15 in the threading direction
0 Tsuru's Chidori array spray nozzle pitch: 100 mm in the width direction, 1 in the threading direction
50 ** Plover array steel plate conveyance speed: 0.6 lIl/s Tempering temperature -650°C Figure 12 shows the above experimental results. In order to increase the tensile strength of the thick steel plate, The water density of the secondary cooling device is Q
, 7 rrr/min -rd or more.

Next, results under typical operating conditions using the apparatus of the first example of the present invention will be shown. The conditions are as follows.

Steel type: A Steel plate size: 251m thick Cooling start temperature: 900°C Cooling stop temperature: Room temperature Water volume of hinge slit jet nozzle on primary cooling device: 3 rrr/
min -m Secondary cooling device pipe nozzle water flow density: 1.5 +vr/min
-rd spray nozzle water density: 2. O+y! /min
'rdThe cooling time in the primary cooling device is approximately 1.
25 seconds, that of the secondary cooling device is about 30 seconds.

Figure 13 shows the above experimental results as a cooling curve.
It shows the relationship between the temperature of a thick steel plate and the cooling time.

According to Fig. 13, the temperature amplitude of the thick steel plate is small, and as a result, even when directly quenched, the Vickers hardness is 370.
The specified strength was obtained, and no uneven structure occurred in the thick steel plate.

Further, under the cooling conditions of this example, the shape of the steel plate is also good.

FIG. 14 shows a second embodiment of the present invention, in which the front cooling device 33 of the secondary cooling device 6 includes vertical lifting frames 51, 54, screws, in addition to the components of the first embodiment. A jack 52, a bullet 55, 56, a draining upper roller 57, etc. are provided.

The elevating frame 51 is provided on the main fixed frame 35 by a screw jack 52 so as to be movable up and down. A guide shaft 53 is lowered from the lift frame 51, and a lower lift frame 54 is provided on the guide shaft 53 so as to be able to move up and down. At the upper and lower portions of the guide shaft 53, bombs 55 and 56 are installed in a spring-like manner to urge the lower elevating frame 54 downward or upward, respectively, so that the lower elevating frame 54 is in a floating state.

The upper draining roller 57 is provided on the lower elevating frame 54, vertically faces one table roller 9 serving as a lower draining roller, and cooperates with the table roller 9 to releasably clamp the thick steel plate 4. This prevents the cooling water of the front cooling device 33 from flowing out to the rear cooling device 34 side, and prevents the cooling water from causing disturbance to the cooling by the rear cooling device 34.

Note that the draining upper roller 57 is located at a clamping position at the position indicated by the imaginary line in FIG. 14, and at a release position at the position indicated by the imaginary line at FIG. 15.

Furthermore, in the secondary cooling device 6, as shown in the first embodiment, it is effective to densely arrange pipe nozzles in the upper part and full cone spray nozzles in the lower part of both the front and rear cooling devices 33 and 34. However, there is a problem in terms of equipment cost.

Therefore, in the second embodiment, in the rear cooling device 34 of the secondary cooling device 6, a hairpin pipe nozzle 58 for cooling the upper surface of the steel plate 4 is used in the upper part, and a flat spray nozzle 59 is used in the lower part. The nozzle arrangement of the front cooling device 33 is coarsened to reduce equipment costs.

The results under typical operating conditions using the apparatus of the second embodiment of the present invention are shown. The conditions are as follows.

Steel type: A Steel plate size: 25mm thick Cooling start temperature: 900℃ Cooling stop temperature: Room temperature Primary cooling device top/hinged slit jet nozzle: 3 nf/min
-m Secondary cooling device pipe nozzle water flow density: 1.5 rrr/min
-g Spray nozzle water flow density: 2. On? /min −
g Secondary cooling device nozzle arrangement Pitch pipe nozzle: Front cooling device; Width direction 75mm, Threading direction 150mm Rear cooling device; Width direction 200M Threading direction 230mm Spray nozzle: Front cooling device; Width direction 100mm Sheet threading direction 15 ON Rear cooling device; Width direction 200 Dragon threading direction 230 *x The cooling time of the first cooling device is approximately 1.25 seconds, and the cooling time of the second cooling device is approximately 1.25 seconds.
The time required for the front cooler is 6.25 seconds, and that for the rear cooler is approximately 22 seconds.

Figure 15 shows the above experimental results as a cooling curve.
It shows the relationship between the temperature of a thick steel plate and the cooling time.

By the way, if the temperature amplitude of the thick steel plate is 400℃ or less,
There is no material problem with thick steel plates, but as shown in Figure 15, the temperature amplitude of thick steel plates is much smaller than 400℃, and as a result of material investigation, it has a Vickers hardness of 365 even when directly quenched. The desired value can be changed, and there are no problems with the material of the thick steel plate.

Next, the mechanical properties of the thick steel plate obtained from the above experiment,
A comparison with the mechanical properties of the thick steel plate obtained in the experiment conducted when determining the cooling curve in the first example is shown below.

(Effects of the Invention) As detailed above, according to the present invention, under the conditions shown in the examples, the upper and lower surfaces of the thick steel plate are cooled from the slit jet nozzle in the primary cooling device. In addition to cooling the steel plate with a water stream, in the secondary cooling device, the upper surface of the thick steel plate is cooled with a cooling water flow from a pipe nozzle, and the lower surface is cooled with a cooling water flow from a spray nozzle. It can prevent the formation of structures, and it can also ensure the strength required for thick steel plates.
During cooling by the primary cooling device, the thick steel plate can be restrained from above and below by the upper presser roller and the table roller.
Cooling is stable and thermal deformation of thick steel plates can be prevented. Furthermore, during cooling by the secondary cooling device, the draining upper roller and table roller that sandwich the thick steel plate from above and below can prevent the cooling water from the primary cooling device from flowing out to the secondary cooling device. This makes it possible to prevent the cooling water of the primary cooling device from disturbing the cooling by the secondary cooling device. In addition, in the primary cooling device, the thick steel plate is cooled in a restrained state, but in the secondary cooling device, the thick steel plate is cooled in an unrestricted state, so that the entire cooling equipment Since the thick steel plate is not cooled in a restrained state, the cooling equipment can be made smaller, its maintenance can be performed easily, and the equipment cost can be reduced.

The present invention has the above advantages and is of great practical benefit.

[Brief explanation of the drawing]

1 to 13 show a first embodiment of the present invention, FIG. 1 is a longitudinal sectional view of the cooling equipment, FIG. 2 is an explanatory diagram showing the equipment layout, and FIG. 3 is a first embodiment of the present invention. Figure 4 is a front view of the pipe nozzle header, Figure 5 is an explanatory diagram showing the arrangement of pipe nozzles, Figure 6 is a front view of the hairpin pipe nozzle header, and Figure 7 is a cross-sectional view taken along the line ■-■ in the figure. is a sectional view taken along the line ■-■ in Fig. 6, Fig. 8 is an explanatory diagram showing the arrangement of full cone spray nozzles, etc., Figs. 9 to 13 are graphs showing experimental results, Fig. 14 15 shows a second embodiment of the present invention, FIG. 14 is a longitudinal sectional view of the cooling equipment, and FIG. 15 is a graph showing experimental results. 2-online cooling equipment, 5.6-.-primary/secondary cooling device, 7-pass line, 9... table roller,
13.52'-screw jack, 19-presser upper roller, 20.21--upper/lower slit jet nozzle, 2
8-- Upper draining roller, 36-- Pipe nozzle,
46- Full cone spray nozzle.

Claims (1)

[Scope of Claims] 1. In an online cooling facility for thick steel plates, which cools hot-rolled thick steel plates 4 sequentially from the front end to the rear end in the sheet passing direction while being conveyed online by table rollers 9, Primary cooling device 5 that cools the thick steel plate 4 while restraining it
and a secondary cooling device 6 that cools the thick steel plate 4 without restraint.
are arranged in the above order in the sheet passing direction, and the primary cooling device 5
, a presser foot upper roller 19 cooperates with the table roller 9 to restrain the thick steel plate 4, and a slit jet nozzle is provided above and below the pass line 7 of the thick steel plate 4 to cool the upper and lower surfaces of the thick steel plate 4 with a cooling water flow. 20, 21, and a draining upper roller that works together with the table roller 9 to sandwich the thick steel plate 4 from above and below to prevent the cooling water from the slit jet nozzles 20, 21 from flowing out to the secondary cooling device 6 side. 28
are arranged in the above order toward the sheet threading direction, and by raising and lowering the presser foot upper roller 19, draining upper roller 28, and upper slit jet nozzle 20, each of these rollers 1
9, 28 and the table roller 9 to releasably restrain or clamp the thick steel plate 4 and to change the position of the upper slit jet nozzle 20 between a cooling work position and a non-cooling work position, A thick steel plate 4 is attached to the device 6.
Pipe nozzles 36, 58 whose upper surface is cooled by a cooling water flow
and spray nozzles 46 and 59 for cooling the lower surface of the thick steel plate 4 with a flow of cooling water. 2. The secondary cooling device 6 has a plurality of cooling devices 33 in the sheet passing direction.
, 34, and the arrangement pitch of each nozzle 36, 46 in the front-stage cooling device 33 is made dense,
2. The online cooling equipment for thick steel plates according to claim 1, wherein the nozzles 58, 59 are arranged at a coarse pitch. 3. The secondary cooling device 6 has a plurality of cooling devices 33 in the sheet passing direction.
, 34, and between the front cooling device 33 and the rear cooling device 34, a thick steel plate 4 is installed in cooperation with the table roller 9.
Claim 1, characterized in that a draining upper roller 28 is provided which holds the cooling water from above and below in a manner to prevent the cooling water from the front-stage cooling device 33 from flowing out to the rear-stage cooling device 34.
On-line cooling equipment for thick steel plates as described in Section 1.