WO2004110662A1 - Controllable cooling method for thick steel plate, thick steel plate manufactured by the controllable cooling method, and cooling device for the thick steel plate - Google Patents

Abstract

A controllable cooling method for a hot rolled thick steel plate, a thick steel plate manufactured by the controllable cooling method, and a cooling device for the thick steel plate. Specifically, the controllable cooling method for the thick steel plate, the method wherein the temperature distribution of the thick steel plate in the lateral direction is uniformized before or at the beginning of the controllable cooling, and the entire part of the thick steel plate in the lateral direction is cooled by the controllable cooling device at a same cooling rate.

Description

 Specification

TECHNICAL FIELD The present invention relates to a controlled cooling method for a thick steel plate, a thick steel plate manufactured by the controlled cooling method, and a cooling device therefor.

 The present invention relates to an accelerated control cooling system for a steel plate that has been hot-rolled, a steel plate manufactured by the controlled cooling method, and a cooling device for the steel plate. Background art

 In the production of thick steel sheets, controlled cooling with a high cooling rate may be performed on the rolled steel sheets in order to secure the mechanical properties required for the steel sheets, especially strength and toughness. Controlled cooling means that after hot rolling, the transformation structure is controlled by rapidly cooling the transformation temperature range (transformation range) from austenite to ferrite (ferrite). This is a technique for adjusting the crystal structure of steel to obtain the desired material such as mechanical properties. At the same time, it is necessary that the cooling be performed uniformly over the entire surface of the steel plate in order to ensure the uniformity of the material properties of the entire steel plate and to suppress the occurrence of strain of the steel plate after cooling. is there. On the other hand, in the current controlled cooling technology, the four periphery zones of the thick steel plate after cooling are in a supercooling state compared to the central part of the steel plate, and the surface of the steel plate is cooled. The fact is that the whole is not cooled uniformly.

In order to meet such demands, Japanese Patent Application Laid-Open No. H10-58026 discloses that cooling water is formed at a predetermined angle with respect to the conveying direction of the steel sheet and at a predetermined angle with respect to the width direction of the steel sheet. Several parallel, spaced There is disclosed a technology in which a high water film collides with the steel sheet surface, and the cooling water after the collision divides equally into the left and right sides of the collision area and flows along the steel sheet surface along the steel sheet surface. The ends of the collision zone are formed so as not to overlap with each other when viewed in the transport direction of the steel sheet.

Cooling method for high-temperature steel sheets has been proposed, which is arranged and cooled in a horizontal direction.

 Japanese Patent Application Laid-Open No. 6-184623 (Japanese Patent No. 2698305)

As a method of cooling a thick steel plate that has been finish-rolled and the rolling wave has been corrected, it has a high cooling capacity provided on the entry side of the control cooling device.

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A means has been proposed in which a high pressure water flow is injected obliquely from a cooling nozzle into a thick steel plate to block the water flow to both ends in the width direction of the steel plate.o

 In addition, JP-A-61-219412 discloses 曰; :: is to measure a plate width distribution in a width direction of a rolled hot steel sheet before cooling the steel sheet, and from the measurement results, The water in the width direction is removed. Next, the calculated water flow distribution is corrected using the temperature data after cooling of the preceding hot steel sheet cooled immediately before the hot steel sheet, and the water injection amount in the width direction of the hot steel sheet is calculated based on the corrected calculation cooling water distribution. O A method for uniform cooling of hot steel sheets has been proposed.

 Also, Japanese Patent Application Laid-Open No. 58-32511 discloses that cooling water impinges on the upper and lower surfaces of a hot-rolled thick steel plate to shield the end of the W1 steel plate.

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A technique for cooling the thick steel plate while shielding it with a gutter to prevent the upper surface cooling water stream from directly colliding with the end of the thick steel plate has been disclosed. Steel width, upper and lower cooling water and

目, and eyes at the start of cooling

j At the end of cooling, a uniform temperature distribution can be obtained in the width direction of the thick steel plate based on the distribution of the degrees in the width direction of the steel plate. Calculate the shielding width at the end of J steel fe ο Based on the calculated result There has been proposed a method of cooling a thick steel plate characterized by controlling the position of the shielding gutter so as to obtain a shielding width.

4 of JP-A-10 58 026 discloses the above, JP-A 6 184 623 No. Gazette (Patent No. 269830 ⁵ JP), JP 61- 219412 discloses Contact Yopi Sho 58- 32511 No. disclosed in Japanese These measures are intended to prevent the phenomenon of overcooling at the end in the width direction of the thick steel plate during cooling in any case, and it is possible to anticipate the effect. However, there still remains a problem in cooling the entire steel plate uniformly. The technical idea of these inventions is that the supercooling that occurs at the widthwise end of the steel plate during cooling and / or cooling is performed by slowing down the cooling rate only at the widthwise end of the steel plate during cooling.

This is a technology to equalize the degree distribution in the width direction of a cooled steel plate. Therefore, according to these proposals, it is necessary to sacrifice the cooling rate to some extent in order to make the temperature distribution in the plate surface of the thick steel plate uniform, and to improve the material quality (bottle neck). t this. Furthermore, these proposals cannot ensure uniformity of the temperature at the top and tail ends of the intermediate rolled material during rolling, and may cause distortion after cooling. . In addition, as described later, changes in the heat transfer type during cooling, such as film boiling and transition boiling, are not taken into account, so the cooling rate at the end of the thick steel plate is controlled. Difficult to do this <

It is assumed that the plate thickness, the cooling start temperature, the cooling end temperature, the cooling water amount, etc. could be adjusted under certain conditions.However, in many cases, it was not possible to adjust when the cooling conditions were changed. * -Ray, actual operation is difficult

Japanese Patent Application Laid-Open No. 61926/1986 discloses a method of cooling a hot steel sheet by water flow cooling while pressing the steel sheet from above and below with multiple rolls. Heh Japanese Patent Application Laid-Open No. H11-139,086 discloses a technique in which a shutoff valve capable of arbitrarily controlling the opening and closing time is provided. Further, a means for detecting a passing position of the hot steel sheet, a means for detecting a temperature profile in a longitudinal direction of the hot steel sheet before the start of cooling, and a cooling operation control means are provided, and a tip of the hot steel sheet during movement is provided. A method for cooling a hot steel plate, characterized by controlling the opening and closing of a header shut-off valve corresponding to the position where the part and / or the rear end is about to pass, has been proposed. However, in Japanese Patent Application Laid-Open No. 61-15926, it is intended to prevent a phenomenon in which a steel plate is overcooled at the end portion in the longitudinal direction during cooling.However, in these proposals, the width of the rolled material is reduced. I in the center The uniformity of clothing cannot be ensured, and there is no means for avoiding distortion after cooling and residual stress at the end of the steel sheet.

 Further, Japanese Patent Application Laid-Open No. 11-267737 discloses a method of manufacturing a steel sheet by manufacturing a steel sheet by controlling and cooling a hot-rolled high-temperature steel sheet. Roughing mill and finishing mill

It is estimated that the cooling equipment provided in the (finishing mill) 1 will reduce the temperature drop near the end of the thick steel plate from the heating furnace to the end of rough rolling, and that it will occur during finish rolling. In order to compensate for the temperature drop near the edge of the steel plate, cooling with a temperature distribution in the width direction of the steel plate is performed, and after finish rolling, the cooling condition is uniform in the width direction of the steel plate. A method of manufacturing a thick steel plate characterized by performing controlled cooling has been proposed. However, Japanese Unexamined Patent Publication No. Hei 11-267737 discloses that, at the end of the plate in the width direction, compensation is performed at an early stage before finish rolling. It is difficult to predict the temperature distribution before finish rolling so that the temperature distribution in the direction becomes uniform 1 / ヽ. This is because, during rolling, the ends of the steel plate are cooled by radiation and natural convection from the sides of the steel plate from the upper and lower surfaces of the steel plate, and in addition to the shape and surface of the steel plate during rolling. Status In order to control the temperature, cooling is performed by descaling with a water jet, and the deviation of the temperature distribution is likely to occur at the width direction end of the thick steel plate and the tail end of the thick steel plate. O In particular, in descaling, operators often judge whether to use or not to use steel plates while checking the condition of the steel plates. With good reproducibility, it is difficult to equalize the temperature distribution at the completion of finish rolling.

In addition, no specific method has been proposed to achieve a uniform temperature distribution in the width direction of the thick steel plate in controlled cooling, and it is difficult to achieve this.

 Also, JP 2001-137943 A discloses that after hot rolling is completed,

There has been proposed a flatness control method for a metal plate characterized by heating a width edge portion of the metal plate and then performing water cooling and / or hot straightening. According to Japanese Patent Publication No. 137943, in the case of heating by a burner, a large-capacity burner must be used due to poor heating efficiency. There is a problem that the heated part of the steel sheet is oxidized and the surface properties are impaired. In the case of induction heating, equipment costs and heating costs are very high, which is not practical. In addition, by some means,

 Even if the uniformity distribution is uniform before cooling, there is no method to cool the steel plate so that the temperature distribution in the plate width direction becomes uniform. As mentioned above, the supercooling occurs due to the boiling phenomenon and the increase in water coverage at the end of the thick steel plate due to the water remaining on the top surface of the steel plate falling from the end. Invention opening

 -An object of the present invention is to solve the problems of the conventional technique described above, and when controlling and cooling a rolled steel plate,

(1) Distribution of skin texture is spread across the width direction of the steel plate and the entire longitudinal direction of the steel plate The present invention proposes a controlled cooling method for a thick steel plate that can be made uniform and has a large cooling rate as a whole, and a thick steel plate and an apparatus manufactured by the controlled cooling method. In addition, a method of cooling a thick steel plate, which has a uniform residual stress distribution in the width direction of the steel plate and in the longitudinal direction of the steel plate, and does not cause a processing shape defect such as a stripping camber, A steel plate and an apparatus manufactured by the controlled cooling method are provided.

 That is, the present invention provides a method of controlling and cooling a steel plate after hot rolling, comprising: a first cooling step (step) for cooling while making the temperature distribution in the width direction of the steel plate uniform; After the uniformization of the temperature distribution in the width direction of the steel sheet, the second cooling step that controls and cools the entire width direction of the steel sheet at the same cooling rate and cooling of the steel sheet that has been hot-rolled is completed. Is the way.

 Also, in the present invention, the first cooling step may include a step of forming a thick steel plate by one or more inlet-side cooling zones in a pass-type control cooling device having a plurality of independent cooling zones. The cooling is performed while limiting the amount of cooling water at both ends in the width direction, and the second cooling step is performed in the width direction of the steel plate by the cooling zone subsequent to the one or more inlet cooling zones. This is a controlled cooling method for thick steel plates that have been hot-rolled, in which the whole is controlled and cooled at the same cooling rate.

 Further, in the present invention, the first cooling step preferably performs cooling while restricting the amount of cooling water at both ends in the width direction of the thick steel plate by a pre-cooling device, and further comprises the second cooling step. The hot-roller, which controls and cools the entire steel plate in the width direction at the same cooling rate, by a pass-type control cooling device having a plurality of independent cooling zones installed at the subsequent stage of the preliminary cooling device This is a controlled cooling method for steel plates that have been rolled.

Further, the present invention provides the method according to the above method, wherein: This is a method for controlling cooling of thick steel plates by limiting the amount of cooling water at both ends of the steel plate with a shielding member (ma skingmember) installed at the end in the width direction of the steel plate.

 Further, the present invention is the method for controlling cooling of a thick steel plate in the above-mentioned method, wherein a cooling water amount at a front end portion in a longitudinal direction of the thick steel plate is limited in cooling in a preceding stage of the control cooling device.

 Further, in the above method, the cooling of the pre-cooling device or the pre-cooling device or the IU control cooling device may include limiting a cooling water amount at a leading end portion in a longitudinal direction of the steel plate. Controlled cooling method for thick steel plate. .

 Further, the present invention provides the above method, wherein the restriction of the amount of cooling water at the tail end in the longitudinal direction of the thick steel plate is controlled by a water passage operated for a predetermined time based on a passage signal of the tail end in the longitudinal direction of the steel plate.

 This is a controlled cooling method for thick steel plates performed by village control means.

 Further, in the above method, the front part of the control cooling device may be provided at an end in a width direction of the thick steel plate in which a water amount of the end in the width direction of the steel plate can be limited between the zones. This is a controlled cooling method for a thick steel plate that can independently shield the cooling water at the widthwise end of the thick steel plate on each zone and on the upper and lower surfaces.

In addition, the present invention provides a method for measuring the temperature distribution in the width direction of a thick steel plate before the controlled cooling in the above method and the temperature drop amount and temperature drop at the end in the width direction of the steel plate from the measured temperature distribution. Analyze the distance from the end in the width direction of the generated steel plate, and based on the results, implement the shielding amount and shielding by the shielding members installed in each cooling zone in front of the control cooling device This is a controlled cooling method for thick steel plates that calculates the number of cooling zones and controls the shielding member based on the calculated result. Further, the present invention provides the method according to the above method, wherein the temperature distribution in the width direction of the thick steel plate is measured before the pre-cooling, and the temperature drop amount and the temperature drop at the end in the width direction of the thick steel plate are determined from the measured temperature distribution. The distance from the end of the steel plate in the width direction is generated, and the shielding amount and cooling time of the shielding member in the pre-cooling device are calculated based on the result, and the standby time is calculated based on the calculated result. This is a controlled cooling method for thick steel plates that is cooled by a cooling device.

 Further, the present invention provides a method for controlling the above-mentioned controlled cooling after hot rolling.

It is a thick steel plate manufactured by controlled cooling.

 Further, the present invention is a passage type control cooling device having a plurality of independent cooling zones, wherein each cooling zone has a cooling water volume density.

1200 liter (hereinafter abbreviated) / min.m ² or more water can be passed through, and the shield that limits the cooling water at both ends in the width direction of the thick steel plate in the cooling zone of the J-th stage This is a controlled cooling device for steel plates where the members are installed.

Further, the present invention is a cooling device in which a pre-cooling device and a control cooling device are sequentially arranged on a rear surface of a rolling mill, wherein the pre-cooling device has an input water density force of S500L (abbreviation of a liter) / min. and m ^{2 or} less, the width direction of the steel plate is installed shielding member to limit the amount of cooling water both side ends in contact is, and said controlled cooling apparatus for pass type having a plurality of independent cooling zone one down shall apply in the apparatus, controlled cooling apparatus der cooling Shueili density force S 1200 L / min. m ² or more water flow possible is the steel plate of the cooling zone

 In addition, the present invention provides the above-described apparatus, wherein the thick steel sheet is controlled and cooled by controlling the operation of the shielding member so that the temperature distribution in the width direction of the thick steel sheet is made uniform.

Further, the present invention provides the above-mentioned apparatus, wherein the water amount control means which operates for a predetermined time in response to a passage signal of the longitudinal end of the thick steel plate is provided. It is a control cooling device for a thick steel plate.

 The present invention also provides the above apparatus, wherein the control cooling device is

It is a controlled cooling device for thick steel plates that uses a slit jet cooling nozzle.

 The present invention also provides the above-mentioned apparatus, wherein the preliminary cooling device uses a laminar flow cooling nozzle, and the control cooling device uses a slit jet cooling nozzle. It is a controlled cooling device for thick steel plates.

 Further, in the present invention, the shielding member placed between the cooling zones at the stepped portions of the control cooling device in the position Px above is arranged independently for each cooling zone and each of the upper and lower surfaces in the width direction of the thick steel plate. This is a control cooling device for thick steel plates with a structure λ that can block the cooling water at the end of the plate.

 In addition, the present invention provides means for measuring the temperature distribution in the width direction of a thick steel plate before controlled cooling in a garment, and the temperature drop amount and temperature at the end in the width direction of the steel plate from the measured temperature distribution. It has a means to analyze the distance from the widthwise end of the thick steel plate where the descent has occurred, and based on the results, a shielding member installed in each cooling zone in front of the control cooling device The present invention relates to a control cooling device for a thick steel plate having means for calculating the amount of shielding to be performed and the number of cooling zones for performing shielding, and having a mechanism for controlling the shielding member based on the calculated result. Before pre-cooling,

From the means for measuring the iSBL degree distribution and the measured temperature distribution, the amount of temperature drop at the end in the width direction of the thick steel plate and the distance from the end in the width direction of the thick steel plate where the temperature drop occurs are analyzed. Means to calculate the amount of shielding by the shielding member of the pre-cooling device and the cooling time based on the results. It is a controlled cooling device for thick steel plates with a mechanism that can control the shielding member and the passing speed in the pre-cooling device o

 In addition, the present invention is the above-mentioned apparatus, wherein the control cooling device for the thick steel plate has a straightening machine between the control cooling device or the preliminary cooling device and the control cooling device. BRIEF DESCRIPTION OF THE FIGURES

Fig. 1: A diagram illustrating the relationship between the surface temperature of the steel plate and the heat release (valueofheatflux) when the high-temperature steel plate is cooled. 0 Fig. 2: Flow of water on the top surface of the steel plate when the steel plate is cooled. O o

Fig. 3: This is a diagram for explaining the 11 plate at the end of the thick steel plate in the width direction and the center of the thick steel plate when cooling the width of the thick steel plate by the conventional method.

Fig. 4 shows the first embodiment of the present invention, and is a diagram for explaining the temperature history of the widthwise end of the thick steel plate and the center of the thick steel plate when cooling control of the widthwise end of the thick steel plate is performed. is there.

Fig. 5: A diagram illustrating the second embodiment of the present invention and illustrating the temperature history of the widthwise end of the thick steel plate and the center of the thick steel plate when cooling control of the widthwise end of the thick steel plate is performed. Yes 0

FIG. 6 is a conceptual diagram of a control cooling device for a thick steel plate that implements the first embodiment of the present invention.

Figure 7: Conceptual diagram of the control cooling device in the present invention o

Fig. 8 is a conceptual diagram of the installation of the cooling water shielding member used in the control cooling device according to the present invention.

Figure 9: A diagram that defines supercooling at the widthwise end of a thick steel plate.

Fig. 10: Control of the first embodiment of the present invention FIG. 4 is a diagram illustrating a control method.

FIG. 11: A diagram showing the temperature distribution in the width direction of the thick steel plate after cooling in the case where the first embodiment of the present invention is carried out and in the case where it is not carried out.

Fig. 12 In the first embodiment of the present invention, the steel plate

 FIG. 2 is a configuration diagram of a control cooling device that performs control

0

13 is a configuration diagram of a control cooling device that performs water level control at the longitudinal end of a thick steel plate in the embodiment of the present invention _i .

0

Fig. 14 is a diagram that defines supercooling at the tail end of the thick steel plate in the longitudinal direction.

Fig. 15A5 15B: It is an explanatory view showing the operation procedure of the cooling water at the time of passing the tip end in the longitudinal direction of the thick steel plate according to the first embodiment of the present invention.

Fig. 16A16B: It is an explanatory view showing the operation procedure of the cooling water at the time of passing the tail end in the longitudinal direction of the thick steel plate according to the first embodiment of the present invention o

Fig. 17 Outline of the control cooling device for thick steel plates implementing the second embodiment of the present invention j (4, Fig.

Fig. 18 • Schematic diagram of the installation of the cooling water shielding member used in the controlled cooling device for thick steel plates according to the present invention.

Fig. 19 • This is an explanatory diagram showing the operation of the laminar fin cooling device for the threaded plate B¾ = at the longitudinal end of the thick steel plate.

Fig. 20 is an explanatory view showing the operation procedure of the laminar fin cooling device of the passing plate B¾F at the tail end in the longitudinal direction of the thick steel plate.

FIG. 21 is an equipment layout diagram (1 a yout) when a straightening machine 30 is installed in the present invention. FIG. 22 is a view for explaining a steel sheet cutting position after cooling according to the embodiment of the present invention.

FIG. 23 shows a method for measuring a stripped camper when the steel sheet 52 after cooling in the embodiment of the present invention is cut.

Fig. 24 shows a method for measuring the stripping cannon when the steel sheet 55 after cooling in the embodiment of the present invention is stripped.

Fig. 25, Fig. 26 • Shows the dimensions and arrangement of the shield plate in the control cooling device in the embodiment of the present invention.

FIG. 27 shows the structure of the shielding member provided in the pre-cooling device in the embodiment of the present invention.

Fig. 28 • The layout of the shielding member in the pre-cooling device in the embodiment of the present invention ο

 Explanation of reference numerals

 1: Plate rolling mill

 2: Steel plate

 3: Roller table (rol 1 er table)

 10: Funa flow cooling device

 11: Upward fern supper header)

 12: Downward, 丄 ower header)

 13, 14: Water flow

 15: M Chang Lu

 16: Forward / backward movement mechanism (of the shielding member)

 17: Photocell (.photo ceil)

 20: Slit-on cooling system

 21: Up one

 22: V

 23: Top-jet cooling nozzle

24: Bottom V jet cooling nozzle 25: Pre-control cooling unit

 26: After the control cooling device

 2 7: Water roll

 28: Upper shielding member

 29: Lower shielding member

 30: Pre-cooling device inlet thermometer

 3 1: Control cooling device inlet thermometer

 32: Control cooling device outlet thermometer

 41: Flow control device

 42: Three-way valve

 5 1: Steel plate tip test material

 5 2: Specimen for measuring the width of the camber

 5 3: Sample material in width direction and longitudinal center

 54: Steel plate tail end; material

 55: Longitudinal strip camber measuring material Best mode for carrying out the invention

The technical concept of the present invention will be described in comparison with a conventional method. Fig. 3 shows the temperature history of a thick steel plate in the conventional method of preventing overcooling of the end of the steel plate in the width direction of the steel plate. The lower part of the clothing is lower than the central part of the thick steel plate.During subsequent control cooling, a shielding member is placed at the end of the thick steel plate in the width direction, or the amount of cooling water is adjusted. As a result, the amount of cooling water that is applied to the ends of the thick steel plate in the width direction is reduced, and the cooling rate is lower than that of the central part of the thick steel plate. This technology equalizes the temperature at the plate edge in the width direction and the center of the plate at the end of cooling. As described below, the problem of Since the cooling rate at the end of the steel plate is lower than that at the center of the steel plate, it is not possible to obtain the same material as that at the center of the steel plate at the end of the steel plate in the width direction. .

 Here, it is considered that the supercooling phenomenon in the four peripheral zones of the steel plate is caused by the following three mechanisms.

 (1) Due to cooling during rolling

 When a steel plate is manufactured by the general rolling process, the four sides of the steel plate are cooled by cooling from the upper and lower surfaces of the steel plate (air cooling) in the rolling process, and the side surface of the steel plate is rolled. Since it is cooled by air (air cooling), the temperature is lower than that of the central part of the thick steel plate. In addition, when such a thick steel plate is controlled and cooled, even if the cooling is performed with a uniform cooling capacity over the entire surface of the thick steel plate, even before cooling, the four peripheral portions of the thick steel plate are already in the center of the steel plate. This temperature distribution is maintained even after cooling because it is supercooled

(2) Due to boiling phenomenon during water cooling

If a steel plate is cooled before cooling in a state where there is a deviation in the temperature distribution in the steel plate, the deviation in the temperature distribution may increase. This will be described in detail with reference to FIG. Figure 1 shows the relationship between the surface temperature of the steel plate and the heat flux when cooling the steel plate at a high temperature of 700 ° C or higher (extraction per unit area and unit time). (Transition of heat flux)). Film boiling occurs when the surface temperature of the steel plate is high, nucleate boiling occurs when the surface temperature of the steel plate is low, and transition boiling occurs in the intermediate temperature range. Has become. In the case of film boiling that occurs when the surface temperature of a steel plate is high, a vapor film is generated between the surface of the steel plate and the cooling water. Heat is transferred by heat conduction in the membrane, and the heat flux (cooling capacity) is low. On the other hand, in the case of nucleate boiling, in which the surface temperature of the steel plate is low, the surface of the steel plate and the cooling water come into direct contact with each other, and a part of the cooling water evaporates from the surface of the steel plate. Complex phenomena occur when water is condensed and extinguished by the surrounding cooling water. As a result, the cooling water is agitated due to the generation and extinction of the vapor bubbles, resulting in an extremely high heat flux.

(Cooling capacity). In this nucleate boiling and film boiling region, as shown in Fig. 1, the higher the temperature of the steel plate, the higher the heat flux (cooling capacity), and the lower the temperature of the steel sheet, the higher the heat flux (cooling capacity). ) Has a lower heat transfer characteristic. Therefore, before cooling,

If there is a deviation in the power distribution, the cooling rate is faster in the hotter part of the steel plate, the cooling rate is lower in the colder part of the steel plate, and the deviation of the plate distribution before cooling is reduced. The surface temperature of a thick steel plate with thermal properties is _0- , but film boiling occurs in the middle temperature range

':)

The transition boiling state is a state in which nucleate boiling is mixed. In the transition boiling state, unlike nucleate boiling and film boiling, a phenomenon occurs in which the heat flux (cooling capacity) increases as the temperature of the steel plate decreases, and the plate thickness of the steel plate is low. The higher the heat flux (cooling capacity), the higher the temperature distribution deviation in the thick steel plate before cooling. The lower the temperature of the thick steel plate, the better the temperature <cooling, and the greater the deviation in the temperature distribution after cooling. Also, as the cooling water density is increased, as shown by the dotted curve in Fig. 1, the surface temperature Ttf at which film boiling shifts to transition boiling increases, and transition boiling starts in the initial stage of cooling. I do. In addition, when the cooling water density is increased, cooling by nucleate boiling becomes possible from the beginning of cooling. On the other hand, when the cooling water mass density is reduced, the surface temperature Ttf at which the transition from film boiling to transition boiling decreases, and film boiling can be achieved during cooling. In general controlled cooling, this point is not considered at all, and cooling is often performed with the cooling water mass density at which transition boiling occurs.Therefore, the deviation of the temperature distribution in the steel plate after cooling is enlarged. There are many cases.

 (3) Due to drainage on the upper surface of steel plate

 When the steel plate is cooled in a horizontal state, the cooling water flows in the outer peripheral direction at the upper part of the steel plate and falls from the end of the steel plate, as shown in Fig. 2. Therefore, at the edge portion A on the upper surface of the steel plate, in addition to the cooling water injected from the nozzle installed on the upper portion of the steel plate, the cooling water discharged to the end of the steel plate As the cooling water is cooled by cooling, the amount of water covered by the upper surface of the steel plate increases, and the cooling rate increases. This phenomenon does not occur because it falls.

 Controlled by the three mechanical mechanisms (.me cnan 1 sm) described above, the temperature of the four peripheral parts of the steel plate after cooling is lower than that of the central part of the steel plate.

Therefore, even if the shape of the steel sheet is uniform immediately after cooling,

 Air cooling after that due to the deviation of clothing distribution

In the process of (air cooling), the heat shrinkage (value of heat shrinkage) is large at the center of the high-temperature steel plate, and the heat shrinkage is small at the four rims of the steel plate.丄 stress) force is generated and the steel plate is distorted.o Even if the distortion is not generated, stress remains at the end of the steel plate and the steel plate is cut at the customer's edge.

 ·

When a warp called a so-called stripping camber occurs around the periphery of the thick steel plate, a problem may occur.o In addition, the periphery of the thick steel plate may be lower than expected. Because the steel is cooled down to the temperature, the material of the steel plate also changes, resulting in high strength. Problems also arise. Therefore, the present invention includes the following two technical ideas.

 (1) Equalize the temperature distribution in the width direction of the thick steel plate immediately before or at the beginning of controlled cooling.

 (2) In controlled cooling, cooling is performed at the same cooling rate from the end in the width direction of the steel plate to the center of the steel plate.

 This will be specifically described with reference to FIGS. Fig. 4 shows that the temperature distribution in the width direction of the thick steel plate is made uniform at the beginning of the controlled cooling, and the controlled cooling thereafter uniformly cools the end of the steel plate and the center of the steel plate at the same cooling rate. In the present invention, which shows the history of the dish in the case of performing the control, the amount of water is controlled by the shield at the end in the width direction of the thick steel plate in the initial stage of the controlled cooling, and the controlled cooling is normally performed in the center of the thick steel plate. Thereafter, when the temperature reaches the same temperature at the central portion of the steel plate and the end portion in the width direction of the steel plate, cooling is performed at a cooling rate of-from the widthwise end portion of the steel plate to the central portion of the steel plate. When a process like the one shown in Fig. 1 is used, the cooling speed and cooling resistance at the end in the width direction of the thick steel plate and the center of the sub-steel plate match. The material in the width direction is homogenized. Ο Fig. 5 shows that the temperature in the width direction of the thick steel plate is equalized by the pre-cooling device before the controlled cooling. The temperature history when cooling at the same cooling rate over the center of the steel plate is shown.In the case of, the cooling speed at the end in the width direction of the steel plate and the center of the steel plate during controlled cooling also match. Can obtain the same effect as Fig. 4.

Next, in the control cooling device, nucleate boiling cooling is performed in order to cool the thick steel plate at a cooling rate of − in the width direction. From Fig. 1, it can be seen that the deviation of the temperature distribution after cooling increases when the surface temperature of the steel plate during cooling is in the transition boiling region, but the temperature in the nucleate boiling region increases. The higher the temperature, the higher the cooling capacity (the higher the heat flux), so even if there is a deviation in the temperature distribution before cooling, the difference is reduced, and the widthwise end of the steel plate and the center of the steel plate are reduced. If the ijm. Degree distribution in the thick steel sheet before cooling is uniform as in the present application, there is no deviation in the temperature distribution in the thick steel sheet from the beginning. After cooling, cooling without deviation of temperature distribution is possible in principle.

 In Fig. 2, at the plate edge on the upper surface of the steel plate, in addition to the cooling water that is installed from the top of the steel plate and radiates from the nozzle, the cooling water that is drained to the end of the steel plate It is explained that the amount of water is increased and the cooling rate is increased because

However, this problem can be avoided by performing nucleate boiling cooling with high momentum of cooling water.When cooling water with high momentum is projected from the nozzle, the injected cooling water penetrates the drained liquid film. To reach the steel sheet table and break the steam film further.

However, cooling is performed in the nucleate boiling region.Cooling in this state is governed by the cooling water radiated from the nozzle, so the effect of cooling by water discharged from the end face force in the width direction of the steel sheet Is small. In order to perform nucleate boiling cooling by the high-ray momentum of the cooling water, a method of increasing the cooling pressure of the cooling water or increasing the cooling water mass density to reduce the momentum of the water by 1¾S is used. Or a cooling nozzle with high water momentum such as a V-jet cooling nozzle

 Examples of the cooling nozzle used in the present invention include a spray nozzle nozzle, a circular tube or a slit-lane nozzle, a circular tube or a slit nozzle cooling nozzle. It ’s okay with chives

To reduce the amount of water and the injection pressure of water, it is preferable to use a circular pipe or a slit jet cooling nozzle with high water momentum. On the other hand, as another advantage of the nozzle with high momentum of water, when the end of the plate in the width direction is shielded by a shielding member, the center of the plate It is possible to greatly change the cooling capacity between the part and the widthwise end of the steel plate, and the temperature difference between the widthwise end of the steel plate and the center of the steel plate in a very short time. It becomes possible to reduce by. This is because the water drained from the widthwise end of the plate is in the vertical direction of the plate; ii Since it has no movement, it cannot break down the steam film and is cooled by film boiling. In other words, if the injection of high-momentum cooling water injected from above and below the thick steel plate is blocked by the shielding member only at the widthwise end of the thick steel plate, the cooling capacity is reduced at the widthwise end of the thick steel plate. It is possible to make nucleate boiling with a high cooling capacity in the center of a thick steel plate with low film boiling.Therefore, the difference in cooling capacity between the end in the width direction of the thick steel plate and the center of the thick steel plate is large. Therefore, the deviation of the temperature distribution in the steel plate can be reduced. Furthermore, there is no cooling in the transition boiling region which enlarges the deviation of the temperature distribution, and uniform cooling of the thick steel plate in the width direction becomes possible.

 In order to achieve such controlled cooling in the nucleate boiling region, for example, when the slit jet cooling is adopted, the water density must be reduced.

It is sufficient to spray 1200 L / min. M ² or more. More preferably,

It is desirable to use 1500 L / min. M ² or more because nucleate boiling cooling can be realized more stably. In addition, from the viewpoint of facility costs and running costs, it is desirable that the water density be 3000 L / min. M ² or less. Here, the slit jet cooling refers to cooling by injecting a high-speed water flow from a slit jet cooling nozzle having a slit-shaped cooling water injection port. However, the momentum and cooling rate of the water are relatively high. A cooling device that uses this slit jet cooling nozzle is called a slit jet cooling device. ,

 To summarize the above, first, control cooling mi or

If the temperature distribution is uniform in the width direction of the steel plate at the beginning of the controlled cooling, the temperature distribution in the width direction of the steel plate after the controlled cooling becomes uniform. By adopting a cooling water nozzle with a low momentum as the cooling nozzle, cooling at the same cooling rate is possible if cooling is performed in the nucleate boiling region o

 In addition, the concept described above can be applied not only to the end of the thick steel plate in the width direction but also to the end of the thick steel plate in the longitudinal direction.

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

 FIG. 6 is a conceptual diagram of the control cooling device for a thick steel plate according to the first embodiment of the present invention. As the control cooling device 20, a through-pass type control cooling device is used. A pass-type control cooling device is a device that cools a plate while passing a thick steel plate through the control cooling device. And excellent controllability of temperature control. For example, in the case of a stop-type control cooling device, the injection of cooling water is stopped when the temperature of the steel sheet reaches a predetermined temperature.

However, it is difficult to control the water cooling time accurately, and as shown by _G , the slab of the thick steel plate is rolled to a predetermined thickness by the plate rolling mill 1 and Then, it is transported on the roller table 3 and is cooled to a cooling stop temperature at a predetermined cooling rate by cooling passing through the control cooling device 20. The control cooling device 20 is provided with an upper header 21 and a lower header 22 sandwiching the pass line of the thick steel plate 2 up and down, and a slit jet cooling nozzle for jetting high-pressure water to this. The nozzles 23 and 24 are attached, and have a function of rapidly cooling the steel plate by extremely high pressure water that collides with the surface of the steel plate 2. Also, the inlet and outlet sides of the control cooling device 20 ΪThere are three sets of clothing, 31 and 32, so that the temperature of thick steel plates can be measured before and after controlled cooling.

FIG. 7 shows a detailed view of the control cooling device 20. The control cooling device 20 is composed of a plurality of cooling zones. Each cooling zone is separated by a draining roll 27, and the cooling water can be adjusted individually. . These cooling zones are referred to as one zone and two zones '·' in order from the position close to the rolling mill. The water density of the V-Site jet cooling nozzle was set to 1200 L / min so that the heat transfer state could be set to nucleate boiling and cooling could be performed at the same cooling rate over the end of the thick steel plate. m ² or more is One Do the water flow can Ru equipment ο

 The control cooling device 20 is divided into a front part 25 and a rear part 26.The front part 25 of the control cooling unit is provided with a shielding member in each cooling zone, and a plate end in the width direction of the thick steel plate. As shown in Fig. 8, which is a cross-sectional view of AA in Fig. 7, the lower part of the upper slit jet cooling nozzle 23, the width direction of the thick steel plate A pair of left and right upper surface shielding members 28 are provided at locations corresponding to both ends, and

■ * ,,

A pair of left and right lower surface shielding members 29 are provided at a position corresponding to both ends in the width direction of the thick steel plate at an upper portion of the slit-tonet cooling nozzle 24, and this is mounted on the thick steel plate 2 by the reverse mechanism 16. This is done by moving the product in and out in the width direction. The upper and lower shielding members 28 and 29 are configured so that they can be moved in and out of the upper surface alone, the lower surface alone, and the upper and lower surfaces simultaneously. The shielding members 28 and 29 installed in front of the control cooling device 20 can be independently moved in and out of each water cooling zone. For example, only one cooling zone is provided with the shielding member, Shielding members can be inserted in all cooling zones of ο

In the first embodiment of the present invention, the first cooling step is After cooling with the cooling zone in the preceding stage restricting the amount of cooling water at the side edges in the width direction of the thick steel plate, and after matching the temperature in the width direction end of the thick steel plate with the temperature in the center of the steel plate As the second cooling step, the cooling zone at the subsequent stage performs controlled cooling at the cooling rate of |

 Here, in limiting the amount of water at the widthwise end of the steel plate, from the viewpoint of determining the number of shielding zones and the shielding distance, the widthwise end of the steel plate before cooling is used. The definition of the temperature drop distance is defined as the temperature drop distance from the position where the slope of 1 in the width direction of the steel plate becomes zero, in the width direction of the steel plate. Defined as the distance to the end, the amount of drop is defined as the temperature at the position where the temperature gradient of the steel plate in the width direction of the steel plate becomes zero, and the temperature at the end of the steel plate in the width direction. The temperature drop amount and temperature drop distance defined by the difference vary depending on the thickness of the material before rolling, its heating conditions, the width and thickness of the steel plate after rolling, the product thickness, and the rolling completion temperature. However, in the case of general rolled material, the 度 1 drop at the end in the width direction of the thick steel plate is about 40 to 50 ° C, 'S 曰度 descent distance of the end portion is about 1 00~ 30 0 mm. At the end in the width direction of the steel plate

 1JDL degree drop or temperature drop at the end in the width direction of steel plate —

 Separation may be measured by rolling-measurement (measurement value by parameter (.parameter) such as J material thickness, etc.), and may be made into a table in advance. A scanning thermometer or the like may be installed so that the temperature distribution can be measured, and the value may be calculated using a computer.

At the center of the width of the steel plate, the cooling is performed normally, and the widthwise end of the steel plate is restricted by the shielding member to limit the amount of cooling water and the width of the steel plate Direction end At this point, the temperature at the center of the steel sheet and that at the end in the width direction of the thick steel plate are made to match as much as possible to the air cooling state. べ く In the first cooling step, Saying

 ■ ijm.

Below 20 ° C, preferably 10. C or less o

 The amount of movement of the shielding member can be determined by shielding the steel plate by the temperature drop distance at the end in the width direction of the thick steel plate as shown in Fig. 9.o Also, the number of cooling zones using the shielding member is 1210. "Showa, however, decides on the following 5.

 The total cooling zone number し た, which is the sum of the number of cooling zones before and after the control cooling device, and the target cooling start temperature and cooling end temperature Λ

 Using the following formula, calculate the cooling rate per zone Δ か ら from the dish difference D Τ (cooling rate).

 Δ Τ = D T / N

 (2) The amount of temperature drop at the end of the thick steel plate in the width direction at the cooling point ED, the number of cooling zones where cooling of the center part of the thick steel plate is possible by ED is equal to X). Obtain from T force. n = E D / Δ T

 (3) From zone 1, which is the first zone before the control cooling device

Use shielding members for the number of cooling zones determined in (2). At this time, the calculated number of cooling zones is not necessarily an integer, but with this equipment, the upper surface shielding member or the lower surface shielding member can be shielded independently, so It is considered that control is possible in 5-zone units. For example, if the number of cooling zones is calculated as 1.4, it is sufficient to use 1.5 zones. Specifically, 1 zone is used.

It is only necessary to use both upper and lower shielding members in the area, and only the upper surface in two zones. -Here, the shorter the equipment length of each cooling zone and the greater the number of cooling zones, the better the temperature controllability of the width direction end of the thick steel plate 0

Also, the cooling water is almost cut off by the shielding member. It is better to set the condition near the air cooling at the end in the direction. This is because, as the temperature at the end of the steel plate in the width direction approaches the temperature at the center of the steel plate, the time required to equalize the temperature distribution between the center of the steel plate and the end of the steel plate in the width direction is increased. And the number of zones in which the shielding member is used increases. As a result, the amount of cooling on the downstream side of the control cooling device is reduced, and the advantage of the present invention is that the cooling rate at the end in the width direction of the thick steel plate coincides with the cooling rate at the center of the thick steel plate. These forces are difficult to obtain.

 Fig. 11 shows the temperature distribution in the width direction of a thick steel plate before and after cooling when cooling was performed by the method described above in the example of the present invention.The conditions were as follows: plate thickness 30 mm, plate width 3200 Controlled cooling was started at 750 ° C at the center of the width of

Cooling was completed at ° C. Before cooling, the temperature drop at the end in the width direction of the thick steel plate was 30 ° C, and the temperature drop distance at the end in the width direction of the steel plate was 200 mm. Although the cooling device used in the embodiment of the present invention has the above-described configuration, the number of cooling zones is 10 and the cooling water density is 1800 L / min. m ² was sprayed. When the number of zones used for the shielding member was calculated using the method described above, the number of zones used was 1.5.Therefore, the shielding member was used for both upper and lower surfaces in one zone, and the lower surface was used in two zones. A shielding member was used only for the part. The amount of movement of the shielding member depends on the temperature drop distance at the end in the width direction of the steel plate.

At 200 mm, the shielding member was moved by 200 mm to a position where the end in the width direction of the thick steel plate was shielded. In the present invention, the temperature drop at the end in the width direction of the thick steel plate, which was 30 ° C before cooling, could almost disappear. On the other hand, as a comparison, the test was also performed for the case where the shielding member was not used, but after cooling, the temperature drop at the end in the width direction of the thick steel plate was 60 ° C, and the temperature drop in the width direction of the thick steel plate was 60 ° C. Say

It can be seen that the deviation of the distribution once expanded In the cooling zone at the preceding stage, cooling is performed while limiting the amount of cooling water in cooling the longitudinal end of the plate in the longitudinal direction, and the temperature at the longitudinal end of the plate and the central part of the plate is reduced. After matching, the cooling zone in the subsequent stage cools the entire length of the thick steel plate at the same cooling rate.

 In this case, the same method as described above for the end of the thick steel plate in the width direction can be applied. In order to control the cooling at the longitudinal end of this thick steel plate, the control cooling device shown in Figs. 6 and 7 must be equipped with a thick steel plate with a controlled cooling zone as shown in Fig. 12. For example, when the passage of the tip of the steel plate 2 is detected by the photocell 17, and the timing for entering the divided cooling zone based on the detection time of the passage of the tip of the thick steel plate by the photocell 17 is used as a reference.

At (timing), a timer (timer) T is set so that the flow control device 41 composed of a flow meter and a flow control valve starts to operate. Ma

 ·

As another method of the flow control device, a three-way valve 42 is installed at the front of the control cooling device as shown in Fig. 13 to allow the cooling water to escape to the outside at the tip end of the steel plate. Thus, a structure that can stop the cooling water injected from the nozzle may be used.o

First, in limiting the amount of water at the tail end of the steel plate, from the viewpoint of determining the number of shielding zones and the shielding distance, information on the tail end of the steel plate before cooling is shown in FIG. Make a definition like 4. The temperature drop village and temperature drop distance at the end of the thick steel plate are the same as the definition of the end of the thick steel plate in the width direction in Fig. 9. The amount of temperature drop and the temperature drop distance vary depending on the thickness of the material to be rolled, the thickness of the material to be heated, the heating conditions, the width and thickness of the product after the completion of rolling, the rolling end temperature, and the like. For the material, the temperature drop at the leading end of the thick steel plate is about 40 to 50 ° C, and the temperature drop at the leading end of the thick steel plate is about 300 to 500 mm.oo The leading end of the thick steel plate Part temperature The amount of drop and the temperature drop distance at the end of the tip end of the thick steel plate are measured by parameters such as the plate thickness of the rolled material and the values are analyzed. In advance, a running thermometer ゃ a surface thermometer with a spot temperature of 10 ^ I よ so that the longitudinal temperature distribution of the thick steel plate can be measured, and the value is calculated by a computer. I don't care

 -In front of the control cooling device based on the information of the above, the steel plate is cooled normally at the center in the longitudinal direction of the steel plate, and at the tail end in the longitudinal direction of the steel plate, the cooling water amount is By limiting the temperature, the temperature at the central part in the longitudinal direction of the thick steel plate and the temperature at the tail end in the longitudinal direction of the heavy steel plate are made to match each other so that the temperature becomes as low as possible. The same concept as the use of the shielding member in the width direction of the thick steel plate can be applied. For example, in order to compensate for the temperature at the temperature drop at the longitudinal end of a thick steel plate, as shown in Fig. 15, a controlled cooling device is used.

Neite the header ¹ "to each cooling 'of 20, first, the cooling water Is in the stopped-like (the state in FIG. 1 5 A), the central portion of the temperature drop portion and the steel plate of the front end portion of the steel plate When the boundary between and enters each cooling zone, the flow control device 41 is activated by the 、, 、, and 冷却 to inject cooling water (Fig. 15

B state)

 In order to compensate for the temperature at the tail end in the longitudinal direction of the Ι-steel plate and the temperature at the descent part, as shown in FIG. When water is allowed to pass through (as shown in Fig. 16A), the boundary between the temperature drop at the tail end of the steel plate in the longitudinal direction and the central part of the steel plate in the longitudinal direction enters each cooling zone. Flow at the timing

The number of timers should be 3 so that the village control device 41 operates to stop the cooling water (the state shown in Fig. 16B). In the same way as the control method in the width direction of the board, it is determined as follows.

(1) From the total cooling zone number N, which is the sum of the number of cooling zones before and after the control cooling device, and the temperature difference DT (cooling amount) between the target cooling start temperature and target cooling end temperature, Calculate the amount of cooling per zone Δ に よ using the formula.

 Δ T = D T / N

 (2) One zone equals the number of zones nL that can cool the central part of the longitudinal direction of the thick steel plate by the temperature drop EDL at the tip of the thick steel plate or at the tail end of the thick steel plate before cooling. From the amount of cooling.

 n L -E D L / Δ Τ

 (3) From the first zone, which is the first zone in the preceding stage of the control cooling device, operate the nL flow control device for the number of cooling zones determined in (2).

At this time, the calculated number of cooling zones is not always an integer. For example, when the number of cooling zones is calculated as 1.4, for example, one zone that is a close integer is used. This is different from the control of the width direction of a steel plate.For example, when cooling water is applied only to the upper surface of the steel plate, the steel plate warps due to the temperature difference generated between the upper and lower surfaces of the steel plate. Although there is a risk of occurrence, such a warp of the longitudinal end of the thick steel plate is preferable because it is difficult to correct it in a correction process such as a roller leveler performed later. Absent. Here, as in the case of the width direction of the thick steel plate, in the longitudinal direction of the thick steel plate, the equipment length of each cooling zone is made as short as possible, and the longer the number of cooling zones, the longer the length of the thick steel plate becomes. The temperature controllability at the tail end in the direction is improved. In addition, it is better to shut off the cooling water at the end of the thick steel plate in the longitudinal direction, so that the condition is close to air cooling. This is the same as controlling the thickness of a steel plate in the width direction. The time required to equalize the length of the central part of the thick steel plate in the longitudinal direction and the longitudinal end of the thick steel plate becomes longer, and the number of water cooling zones where flow control is performed also increases. More. As a result, the amount of cooling on the downstream side of the control cooling device is reduced.

However, the effect of the present invention is that it is difficult to obtain a measure in which the cooling speed at the longitudinal end portion of the thick steel plate and the central portion of the thick steel plate in the longitudinal direction are difficult to obtain.

 As described above, the same temperature control as that at the end of the thick steel plate in the width direction can be applied to the temperature drop portion at the end of the thick steel plate in the longitudinal direction. Cool to the right temperature

 -It's not that it is rejectable o

 In addition, in order to eliminate the temperature drop in the width direction of the thick steel plate, the number of zones used by the shielding member is controlled, and the length of the thick steel plate is controlled.

 丄

The number of cooling zones that control the flow rate of water at the longitudinal end of the thick steel plate is controlled to eliminate the downward descent at the tail end in the hand direction. It is possible to control the tail end of the steel plate in the longitudinal direction independently. For this reason, for example, the

 Even if the temperature drop is 30 ° C and the temperature drop at the end of the thick steel plate in the longitudinal direction is 70 ° C, the temperature distribution can be made uniform even with different temperature drops. Become o

 FIG. 17 is a conceptual diagram of a control cooling device for a thick steel plate according to a second embodiment of the present invention. The hot-rolled steel plate 2 is transported on the roller table 3 and is sequentially conveyed to the pre-cooling device 10 and the control cooling device 20, where it is cooled to a cooling stop temperature at a predetermined cooling rate. ·

 The pre-cooling device 10 is a cooling device of the control cooling device HX [S.S.] in order to achieve the first cooling step of the present invention.

, A few <

1 dish drop is 40 ~ It is only necessary to have the ability to cool about 50 ° C. Here, in the pre-cooling device 10, an upper header 11 and a lower header 12 are arranged with a pass line (thickness) of the steel plate 2 sandwiched above and below, and nozzles provided in these headers are provided. (Not shown), the water currents 13 and 14 hit the front and back surfaces of the steel plate 2 to enable laminar flow cooling. Laminar flow cooling is a method in which a laminar flow (laminar flow) generated when the water flow is slow is used to form a water film on the surface of a thick steel plate and cool it. The cooling rate is relatively small. A cooling device that uses laminar flow cooling is called a laminar flow cooling device.

As in the first embodiment of the present invention, the control cooling device 20 includes an upper header 21 and a lower header 122 sandwiching the pass line of the thick steel plate 2 above and below. Slit jet cooling nozzles 23 and 24 that eject water are installed, and have the function of rapidly cooling steel plates by extremely high pressure water that collides with the surface of the steel plates. Have. In addition, the control cooling device 20 is composed of a plurality of cooling zones as shown in FIG. 7, and each cooling zone is separated by a draining roll 27 (not shown). In addition, the cooling water density can be adjusted individually. These cooling zones are referred to as one zone and two zones in order from near the rolling mill. The water flow rate is in the nucleate boiling state, Ni Let 's that can cooled with Wataru connexion uniform cooling rate in the end portion of the steel plate, and has a 1 200 L / min. M ² or more water flow can Ru facilities.

 In addition, surface thermometers 30, 31, 32 are installed on the inlet side of the pre-cooling device and the inlet and outlet sides of the control cooling device, so that the temperature of thick steel plate can be measured before and after cooling. .

In the second embodiment of the present invention, the pre-cooling device 10 having these laminar-flow cooling devices and the slit jet cooling nozzle cooling device are provided. Control cooling device 20 with cooling device is also used. In the pre-cooling device having a runner cooling device, the cooling water amount at both ends in the width direction of the thick steel plate 2 and the leading end of the thick steel plate is controlled. The adjustment of the cooling water amount is shown in Fig. 18 as A in Fig. 17

A section view

Thus, in the pre-cooling device 10, at the lower part of the upper header 11 and at the upper part of the lower header 12, corresponding to the both ends in the width direction of the thick steel plate By providing the member 15 and moving it in and out in the width direction of the thick steel plate 2 by the reverse

No.

 In the second embodiment of the present invention, the case of the first stage of the control cooling device in the first embodiment is replaced with a spare 10 to replace 7 L.

By installing a shielding member over the entire length of the equipment in the pre-cooling device 10, the temperature distribution in the width direction of the thick steel is made uniform, and the control cooling device 20 is used. In other words, it is a technique of cooling at the same cooling rate from the widthwise end of the thick steel plate to the center in the widthwise direction of the thick steel plate. As described in the first embodiment of the present invention, the temperature drop at the end of the thick steel plate in the width direction is 40 to 50.

° C, so that in order to make the temperature distribution in the width direction of the thick steel plate uniform, cooling is not performed at the end in the width direction of the steel plate, but only at the center in the width direction of the steel plate. Cool at 50 ° C. Since the target cooling amount is extremely small, it is easier to control the cooling rate for a relatively long time by lowering the cooling rate, but it is easier to control ^ The method according to the embodiment can improve the uniformity of the temperature distribution in the width direction of the thick steel plate more than the method according to the first embodiment. In this method, equipment that can cool at about 40 to 50 ° C only needs to be provided in front of the control cooling device, so that extremely inexpensive cost is possible. The control method is As in the case of the first embodiment Hp described above, the use zone of the shielding member may be implemented before the preliminary cooling device.The number of zones used by the shielding member is determined by using the entire length of the cooling device. Also good,

 When a shielding member is used in front of the pre-cooling device, as in the case of the user, the end of the steel plate is cooled in the post-stage of the pre-cooling device, so that controlled cooling starts after that. Is lower than the latter

. For this reason, it is preferable to use a shielding member over the entire length of the cooling device, as in the latter case, to perform cooling by changing the passing speed.

 Here, in limiting the amount of water in the plate m part, from the viewpoint of determining the cooling time and the shielding distance, information on the plate end before pre-cooling is shown in FIG. 9 in the first embodiment. Definitions as described in Section 5 are made. This was also explained in the first embodiment.

 The temperature drop amount and the temperature drop distance of the same <and <vary depending on the thickness of the material before rolling, the heating conditions, the width of the material after rolling, the product thickness, and the temperature at the end of rolling. The measured values may be analyzed and tabulated in advance, or a surface thermometer such as a traveling thermometer may be installed before the control cooling device so that the temperature distribution over the entire surface of the steel plate can be measured. The value may be calculated by a calculator.

 Based on this information, in the pre-cooling device, the central part of the thick steel plate in the width direction is cooled at all times.

 The center of the steel plate in the width direction and the ends of the steel plate in the width direction should be restricted so that the air-cooling state is as close as possible.

Match one dish degree. The amount of movement of the shielding member should be limited by the temperature drop distance at the end of the plate in the width direction of the thick steel plate in Fig. 9. In addition, the cooling time required for cooling by the pre-cooling device 10 is calculated only for the temperature drop at the end in the width direction of the thick steel plate before cooling, and the passing speed is calculated from the BX length and the cooling time. I'll decide In addition, the calculation can be performed more easily than in the first embodiment. Also, unlike the first embodiment, since the cooling time can be controlled continuously instead of controlling the number of cooling zones in 0.5 zone units, the temperature distribution in the width direction of the thick steel plate can be controlled. This makes it possible to increase the uniformity of the image.

Further, in the pre-cooling device, the cooling water density is, 1 00 L / min. M on ² or more, 500 L / min. M ² or less of favored arbitrary to keep in range. As described in Means for Solving the Problems, in order to cool the entire steel plate in the width direction at a uniform cooling rate, it is only necessary to prevent overcooling due to drainage from the end in the width direction of the steel plate. For this reason, it is better to use a cooling system with a high momentum (specifically, use a cooling nozzle with a slit jet type of 1,200 L / min.m ^{2 or} more). explained. For this reason, this pre-cooling device cannot achieve the same cooling rate from the end in the width direction of the steel plate to the center in the width direction of the steel plate, but in the first place, the end in the width direction of the steel plate The temperature drop of the part is very small, 40 to 50 ° C, and the temperature in the width direction of the thick steel plate before control cooling in the high temperature range where the material is not determined may be equalized. Therefore, the heat transfer characteristics in the film boiling region in FIG. 1 where the amount of water is low and the surface temperature is high are applied. In a state where there is a temperature distribution deviation in the width direction of the steel plate before cooling, the cooling capacity (heat flux) becomes higher as the surface temperature of the steel plate becomes lower in the transition boiling region in FIG. In the region where the temperature is low before cooling, such as at the end of the film, the cooling capacity (heat flux) increases at an accelerated rate, but the higher the temperature in the film boiling region, the higher the cooling capacity (heat flux). The deviation of the temperature distribution in the width direction of the steel plate before cooling does not increase. Therefore, if the pre-cooling device is controlled so that it can be cooled by film boiling, it is possible to prevent overcooling of the plate end of the thick steel plate due to the change in the boiling state. It is. Therefore, it is only necessary to consider the supercooling caused by the increase in the water volume due to the drainage at the end of the steel plate, and the temperature distribution in the width direction of the steel plate can be relatively easily made uniform. In addition, since the cooling capacity (heat flux) of film boiling is low in the first place, it is possible to control the cooling at a temperature drop of 20 to 30 ° C at the end of the thick steel plate with good control. There is also. Is a facility to achieve this, cooling water density of the pre-cooling device 10, 100L / min. M ² or more, if 500L / min. M ² or less, Ru can realize a stable film boiling. Also, in order to achieve film boiling, it is necessary to have a stable vapor film between the steel plate and the cooling water, and water cooling such as spray cooling, mist cooling, laminar flow cooling, etc. It is preferable to use one with low momentum.

On the other hand, the adjustment of the amount of cooling water at the leading end of the steel plate is the same as that described in the first embodiment, and the water flow is cut off when passing through the leading end of the steel plate in the longitudinal direction. (Cut off). Specifically, it is as shown in Figure 19. That is, the upper header 11 of the laminar flow cooling device 10 is divided (in the example of FIG. 19, 11a to lid are divided into four parts). For example, the tip passage in the longitudinal direction is detected by the photocell 17, for example. Then, the timers T1 to T4 are set so that the divided upper header starts operating based on the detection time of the passage of the longitudinal end of the thick steel plate by the photocell 17 as a reference. set. As a result, the upper header 11 operates according to the progression stage of the thick steel plate shown in FIG. 19, so that the water cooling at the distal end in the longitudinal direction of the thick steel plate is eased. The cooling water injection timing by the timer is the same as in the first embodiment, based on the temperature drop length at the longitudinal end of the steel plate measured beforehand or before pre-cooling. The same control as described in the first embodiment Just do it. The adjustment of the amount of cooling water at the tail part in the longitudinal direction of the thick steel plate may be performed as shown in FIG. 20 in the same manner as described above. Can be realized by the same method as the first embodiment of the present invention.

 The reason why the cooling water is cut off at the longitudinal end of the thick steel plate as described in _t ID is that a shielding member is placed at the end of the steel plate in the width direction. Cooling water

 The area is limited, and only the center in the width direction is cooled and | pj is performed. For this reason, if the plate is in the same direction as the amount of descent in the plate width direction and the end of the plate in the longitudinal direction of the plate, and if it is 1 plate B, the control cooling BU is applied to the entire surface of the plate. In the second embodiment, the cooling water at the end in the width direction of the thick steel plate extends over the entire length of the pre-cooling device, although it is possible to make the cooling water uniform.

 When limiting the village, the width direction of the steel plate and

} If it is not possible to control the longitudinal direction of the

, Says in the width direction of steel plate

 Only one of the clothing temperature distribution or the temperature distribution at the tip end of the thick steel plate can be homogenized, o

 As a method for equalizing both the wording distribution in the width direction and the temperature distribution in the longitudinal direction of the thick steel plate, as in the first aspect of the invention, a plurality of cooling zones are provided even in the pre-cooling device. A method of controlling the amount of cooling water at the plate edge in the width direction of the thick steel plate before the pre-cooling device, and equalizing the temperature distribution in the width direction of steel and & In the following control cooling system

As described in the first embodiment, there is a method of performing controlled cooling of the leading end in the longitudinal direction of the thick steel plate, but the latter is preferred. In the former method, it is impossible to continuously adjust the cooling time by controlling the number of cooling zones of the pre-cooling device, and the uniformity of the high-precision wording distribution in the width direction of the thick steel plate is completely achieved. Defects that cannot be enjoyed ο 3; up to uniform temperature distribution in the longitudinal direction of steel plate If the temperature drop at the leading and trailing ends of the thick steel plate is larger than the temperature drop at the end in the width direction of the thick steel plate, the width of the thick steel plate At the center in the direction and in the longitudinal direction, cooling must be performed in accordance with the end of the tip where the temperature drop is large. For this reason, one plate is lower than when the temperature distribution in the width direction of the thick steel plate is made uniform.

 However, control cooling must be performed from nos. However, from the viewpoint of material quality, control cooling must be started. When controlled cooling from iS ^, ferrite transformation occurs before controlled cooling.

• 9, There is a concern that hardenability will decrease. In many cases, emphasis is placed on the uniformity of the temperature distribution at the ends in the width direction of thick steel plates. Therefore, as in the latter method, the width direction is first made uniform by pre-cooling.

It is better to make the longitudinal temperature distribution of the thick steel plate uniform by controlled cooling.

 In the above, the method according to the first embodiment and the method according to the second embodiment have been described in the present invention.

 Either or both may be implemented according to the features of (1). For example, if precooling is not possible at the beginning of cooling from the viewpoint of material, or if there is no space to introduce a precooling device, the first embodiment can be adopted. If it is desired to increase the uniformity of the material in the width direction of the thick steel plate rather than in the longitudinal direction, or when the original pre-cooling device and the control cooling device have equipment arranged in a straight line, the second embodiment should be used. Just adopt

 In addition,

In the form (1), the straightening machine 30 can be installed in front of the control cooling device 20. Further, in the second embodiment, a straightening machine 30 can be installed between the pre-cooling 3. la. 10 and the control cooling device 20 as shown in FIG. 21. . Before cooling If the flatness of the steel plate is poor, the distance between the nozzle and the steel plate changes depending on the position of the steel plate, and the temperature uniformity may be slightly worse. If the shape of the steel sheet is corrected, controlled cooling can be performed more uniformly, and uniformity of the material and flatness of the product steel sheet can be easily ensured. Note that, if the ¾α main machine 30 is further provided on the rear side of the control cooling device 20, the force s can be obtained. The shielding member used in the present invention is a block-type plate; fx gutter-shaped plate as long as it shields the widthwise end of the thick steel plate from water from nozzles and the like. Any shape such as (cana li cu ated type) may be used, but since it always receives high-pressure water, a highly rigid structure composed of corrosion-resistant material is desirable. In addition, if a shielding plate is used, which is most preferable because of the convenience of preparation and handling of the shielding member, the size should be slightly longer than the maximum temperature drop distance at the edge of the shielding plate. . In this case, if the temperature drop distance at the edge of the plate is long, the force cannot be applied.On the other hand, if the temperature is too long, the shield mechanism will be too large. Attachment of the shielding plate to a narrow space inside the device becomes difficult. As mentioned earlier, the general temperature drop distance at the edge of the plate is about 300 mm at the maximum.

The length should be about 400 mm from 0 mm force. In addition, as the material, the cooling water used in the production line often contains corrosive substances such as elemental steel, so that corrosion of stainless steel or the like can be prevented by using steel materials or steel sheets. It is more preferable to use anti-corrosion coating or carbon steel sheet coated with zinc chrome, etc. Example Controlled cooling according to the present invention and a conventional method (comparative example)

Table 1 shows the operating conditions in the case of controlled cooling by), and Table 2 shows a comparison of the effects. The conditions for the treated steel sheet were a steel sheet with a thickness of 25 mm, a width of 3800 mm, and a length of 25 m.Control cooling was started at 750 ° C at the center of the width of the thick steel sheet, and cooling was performed at 550 ° C. finished. The strength level of the steel plate is 490MPa class, and the allowable range is 490 to 610MPa. For the steel plate before cooling, the temperature drop at the end in the width direction of the steel plate in Fig. 9 is 30 ° C, the temperature drop distance at the end in the width direction of the steel plate is 200mm, and the length of the steel plate in Fig. 14 is The temperature drop at the leading end in the direction is 50 ° C, and the temperature drop at the leading end in the longitudinal direction of the thick steel plate is 500 mm. In addition, in Invention Examples 1 and 2, the shielding members (hereinafter, referred to as shielding plates) used for the control cooling device were, as shown in FIGS. 25 and 26, four upper and lower members for each cooling zone. A Zn-Ni steel plate with a length of 300ιη πιχ φ 畐 350 mm and a thickness of 7 ixL m was used. In addition, the cooling water cut off by this shielding plate is set at an angle of 15 ° with respect to the horizon so that the cooling water does not fall again toward the steel plate. Also, in Invention Examples 3 and 4, the shielding member used for the pre-cooling device was aruru.

 HZ length (length 1

0m) ί; In order to be able to shield the cooling water over this, 遮蔽 η-Ni plated steel sheet is processed into an L-shaped shielding member (length 10m x width 350m mx thickness 7m m X i¾ 50mm) Installed. In the pre-cooling device, the length of the shielding member is extremely long, and there is a risk that the shielding member may cause 7 buckling due to its own weight.Therefore, m 27 should be used to secure the rigidity of the shielding member. As shown in Fig. 28, the L-shape was machined and the ribs were attached at intervals of 500 mm, and the vertical plate came inward in the width direction. this The purpose of this is to shield the end of the thick steel plate so that the cooling water blocked by the shielding member does not fall toward the thick steel plate.

Inventive Example 1 is an example corresponding to Embodiment 1, and cooling was performed using the apparatus described with reference to FIGS. Detailed control conditions will be described with reference to FIG. The number of cooling zones is 15 zones, the equipment length per zone is 1.Οπι, and the total length of the control cooling device is 15m. Further to 1500L / min. M ² injects cooling water density in each zone, this's and Kino cooling rate is about 30 ° C / s.

Since cooling starts at 750 ° C and ends at 550 ° C, the cooling amount per zone is (750 ° C-550 ° C) / 15 zones = 13.3 ° C. Become . Therefore, the number of zones required to use the shielding member at the end in the width direction of the thick steel plate is 30 ° C / 13.3 ° C = 2.26 zones. For this reason, the actual number of zones used was set to 2.5, and from zone 1 the upper and lower surfaces were used for 2 zones, and only the lower surface was used for 3 zones. In addition, the amount of movement of the shielding member is such that the cooling water can be shielded by 200 mm from the end in the width direction of the steel plate because the temperature drop distance at the end in the width direction of the steel plate is 200 mni. Set. On the other hand, the flow control in the longitudinal direction of the thick steel plate was performed by the flow control device as shown in Fig.12. The temperature drop at the longitudinal end of the thick steel plate is 50 ° C; however, the required number of zones is 50 ° C / 13.3 ° C = 3.8 zones, so 1 to 4 zones Carried out. Also, as shown in Fig. 15A, wait at the tip of the plate in the longitudinal direction without cooling water, as shown in Fig. 15A. The cooling water is injected in the state shown in Fig. 15B after entering the cooling device by a distance. The same control as shown in Fig. 16 was performed on the tail end of the thick steel plate in the longitudinal direction. Since the cooling rate by the control cooling device is about 30 ° C / s, the cooling time required for control cooling is (750 ° C-550 ° C) / 30 ° C / s = 6.6 seconds. , Control cooling system threading The speed was (15m / 6.6sec) x60 = 134mpm.

Invention Example 2 is another example corresponding to Embodiment 1, and the cooling water flow density was 1200 L / min. M ² . The conditions other than the cooling water density are the same as in Invention Example 1.

Inventive Example 3 is an example corresponding to Embodiment 2, in which the apparatus described with reference to FIG. 17 is first cooled by the pre-cooling device 10 to obtain the temperature distribution of the thick steel plate in the width direction. After making the deviation uniform, cooling was performed by the control cooling device 20 to make the deviation of the temperature distribution at the end of the thick steel plate in the longitudinal direction uniform. The pre-cooling device 10 in FIG. 17 has a facility length of 10 m and a cooling water volume density of 100 L / min. M ² , and the cooling rate at this time is about 4 ° C / s. Since the temperature at the end of the plate in the width direction is 720 ° C, the time required to cool the center of the plate in the width direction from 750 ° C to 720 ° C is (750.C-720.C). ) / 4 ° C Is = 7.5sec. Therefore, the threading speed of the pre-cooler 10

(10m / 7.5sec) x60 = 80mpm. In addition, as shown in Fig. 19 and Fig. 20, the longitudinal end of the thick steel plate enters the length of the longitudinal end of the thick steel plate by the temperature drop distance (500mm) and then cools down sequentially. We sprayed water. In addition, the amount of movement of the shielding member is such that the cooling water can be shielded by 200 mm from the widthwise end of the thick steel plate since the temperature drop distance at the end of the thick steel plate in the width direction is 200ιηπι. Set.

Also, the control cooling device in FIG. 17 has the same number of cooling zones as in Invention Example 1, the number of cooling zones is 15, the equipment length per zone is 1.0 m, and the total length of the control cooling device is 15 m. . Further to 1500L / min. M ² injects cooling water in each zone, preparative-out of the cooling rate of this is 30 ° C / s. In the control cooling device 20, cooling starts at 720 ° C and ends at 550 ° C, so the cooling amount per zone is (720 ° C-550 ° C) / 15 zones = 11.3 ° It becomes C. Longitudinal tail of steel plate In the flow control in the end direction, the temperature drop at the leading end in the longitudinal direction of the steel plate is 50 ° C, but the deviation of the temperature distribution is eliminated by 30 ° C by the pre-cooling device. In the controlled cooling device, the length of the longitudinal end of the thick steel plate for 20 ° C

 It is necessary to control the amount of dish drop

. Therefore, the required number of zones was 1.8 zones at 20 ° C / 11.3, so we implemented from 1 to 2 zones. At the tip of the plate in the longitudinal direction, as shown in Fig. 15A, it waits at first without cooling water injection as shown in Fig. 15A, and the temperature at the tip of the plate in the longitudinal direction is shown in Fig. 15A. After entering the cooling device for a descent distance (500 mm), the cooling water is injected at the state shown in Figure 15B. Similarly, control as shown in Fig. 16 was performed on the tail end of the thick steel plate in the longitudinal direction. Since the cooling rate of the control cooling device is about 30 ° C / s, the cooling time is (720 ° C-550 ° C) / 30 ° C / s = 5.7 sec. Plate speed is

(15m / 5.7sec) x60 = 158mpm. The flow rate at the tail end in the longitudinal direction of the thick steel plate was adjusted using a flow rate control valve as shown in Fig. 12.

 Inventive Example 4 is an example in which a straightening machine is installed between the preliminary cooling device and the control cooling device in Embodiment 2, and the cooling conditions are the same as those of Invention Example 3.

 In Comparative Example 1, cooling was performed at the same passing speed by the same equipment as that of Invention Example 1, but the shielding member for controlling the temperature in the widthwise end portion of the thick steel plate and the longitudinal direction of the thick steel plate were used. This is an example in which flow rate control for controlling the temperature at the tail end is not performed.

Comparative Example 2 uses the same equipment as Invention Example 2 to cool at the same passing speed in the pre-cooling device and the control cooling device, but to control the temperature at the end in the width direction of the thick steel plate. This is an example in which the flow rate control for controlling the temperature at the end of the longitudinal end of the shield member and the thick steel plate is not performed. In Comparative Example 3, the same equipment as in Invention Example 2 was used, and only the pre-cooling device was used.However, the amount of water at the end of the plate in the width direction and the end of the plate in the longitudinal direction was measured. This is an example when control is not performed. In this example, pre-cooling device 10 in FIG. 1 7 is cooled water density in equipment length 1 0 m is 500 L / min. M to ^z injection. The cooling rate at this time is 14. The cooling time required to pass and cool the steel plate from 750 ° C to 550 ° C is 14.3 sec. Therefore, the pre-cooling device was passed at a passing speed of 42 mpm. This is the reason why the cooling rate is increased by increasing the amount of water compared with the pre-cooling device of Invention Example 3, but since the material is produced only by the pre-cooling device, the cooling speed is high. Was set higher. At this time, no water flow control was performed at the end of the thick steel plate in the longitudinal direction, and no shielding member was used in the width direction of the thick steel plate.

 Comparative Example 4 uses the same equipment as Invention Example 3 and is the same as Comparative Example 3.Cooled only by the pre-cooling garment, but the widthwise end of the thick steel plate and the longitudinal end of the thick steel plate An example of the case where the water amount control of the section is performed will be described. In this example, cooling is performed at the same passing speed and cooling water density as in Comparative Example 3. Also, the amount of movement of the shielding member

However, since the temperature drop distance at the end of the thick steel plate in the width direction was 200 mm, the s-ru was set so that the cooling water was shielded by 200 mm from the end of the thick steel plate in the width direction. In addition, as shown in Fig. 19 and Fig. 20, the longitudinal end of the thick steel plate enters the longitudinal end of the thick steel plate by the temperature drop distance (500mm), and then in order. Cooling water was sprayed.

Comparative Example 5 uses the same arrangement as that of Invention Example 1, except that the end portion in the width direction of the thick steel plate and the end portion in the longitudinal direction of the thick steel plate over all the cooling zones of the control cooling equipment. An example in the case where the water amount control is performed will be described. In this example, the same threading speed and Cooling is performed at the cooling water density, but the water content of the shielding member and the tail end of the thick steel plate in the longitudinal direction was adjusted for all cooling zones.The amount of movement of the shielding member was the temperature of the plate edge in the width direction of the thick steel plate. Since the descent distance is 200 mm, it is set so that the cooling water at the end of the plate in the width direction of the steel plate can be blocked for all cooling zones 200 mm from the end of the plate in the width direction of the plate. did. On the other hand, as shown in Fig. 15A, at the beginning of the longitudinal direction of the thick steel plate, the cooling steel plate is kept on standby without cooling water, as shown in Fig. 15A. The cooling water has entered the cooling device by the temperature drop distance (500 mm) of Fig. 15 B. Cooling water is injected in Fig. 15B. Similarly, the control shown in Fig. 16 was performed on the tail end of the steel plate in the longitudinal direction.

 Here, the end in the width direction of the steel plate is defined as shown in Fig. 9. Here, the temperature drop distance is defined as the distance from the position where the temperature gradient of the steel plate in the width direction of the steel plate becomes zero to the edge of the steel plate in the width direction, and the temperature drop amount is the thickness It is defined as the difference between the temperature at the position where the steel sheet temperature gradient in the width direction of the steel sheet becomes zero and the temperature at the end of the steel sheet in the width direction. Therefore, if the temperature at the end of the steel plate in the width direction is lower than the temperature at the center of the steel plate, the temperature becomes a positive value, and the temperature at the end of the steel plate in the width direction becomes the center of the steel plate. If the temperature is higher than the temperature of the section, the value will be negative. The end in the longitudinal direction of the thick steel plate is defined as shown in Fig. 14 and is the same as that defined by the temperature drop in the width direction and the temperature drop distance in the width direction of the thick steel plate.

FIG. 22 is a diagram for explaining the removal of a thick steel plate after cooling. Specimen 51 of the thick steel plate cut at a position of 150 mm from the longitudinal end and tail end of the steel plate 51, and the tail material 54 of the thick steel plate and the width and thickness of the thick steel plate From sample 53 at the center in the longitudinal direction of the steel sheet, Cut out the pull and measure the tensile strength. The strength of the end of the thick steel plate is determined by the tensile strength of a test piece cut out from the end of the sample at a distance of 100 mm from the end of the sample at the center in the width direction and the longitudinal direction of the thick steel plate. Was measured.

 The specimen 52 for measuring the camber in the width direction of the thick steel plate and the specimen 55 for measuring the camper in the longitudinal end of the thick steel plate are shown in Fig. 23 and Fig. 24, respectively. Then, cut into strips. Figure 23 shows the stripping position in the width direction of the thick steel plate and the measuring position for the camber measurement specimen. The strip was cut at a position 300 mm from the end of the thick steel plate, and the maximum bending of the strip that was cut into strips at that time was set to • 9 as the width-direction crossover member. Fig. 24 shows the cutting position of the test piece for measuring the camber in the longitudinal direction of the thick steel plate and the measuring position of the camper.

. The strip is cut at a position 300 mm from the tail end in the longitudinal direction of the thick steel plate, and the maximum bending amount of the thick steel plate cut into a book at that time is determined by the longitudinal bend member. And

 · ·

 As can be seen from Table 2, when the present invention is applied, despite the high cooling rate as a whole, the remarks on the widthwise end of the cooled steel plate in the width direction are obtained. The amount of drop is from -4 ° C to 3 ° C, which is smaller than the temperature drop before cooling (30 ° C). O The 1J-day HL degree at the end of the longitudinal end of the thick steel plate About the amount of descent b Same as-7 ° C 10 ° C

However, it is smaller than the temperature drop before cooling (50 ° C). As a result, the residual stress in the width direction of the thick steel plate is reduced, and the camber after cutting is small. In addition, the tensile strength of the thick steel plate is also approximately equal to the longitudinal end of the thick steel plate, the widthwise end of the thick steel plate, and the center of the thick steel plate in the longitudinal and width directions.

It is about 550MPa and stable. In addition, in Inventive Example 4, after the straightening was performed after the preliminary cooling, the controlled cooling was performed. However, the shape of the thick steel plate before controlled cooling was much flatter than in Invention Examples 1 and 2 in which no straightening was performed, and as a result, the uniformity of the wording distribution in cooling by controlled cooling was further improved. As a result, the lower end of the steel plate in the width direction after cooling and the end portion in the longitudinal direction of the steel plate after cooling had less drop, and the amount of camber after cutting was further reduced.

 On the other hand, the end of the thick steel plate in the width direction and the end of the thick steel plate in the longitudinal direction are different from each other.

 In Comparative Examples 1 to 3 in which village control was not performed, the drop in the width direction of the thick steel plate after cooling and in the longitudinal end portion of the thick steel plate became larger than that before cooling. However, a large canopy occurred after the cut of the small fruit. In addition, the tensile strength of the thick steel plate at the end in the width direction and at the longitudinal end of the thick steel plate is larger than that at the center of the steel plate. I'm doing it.

 3d 7 J ^ The water amount at the end in the width direction of the steel sheet and the end in the longitudinal direction of the thick steel sheet was controlled, but in Comparative Examples 4 to 5, which did not follow the method of the present invention, The fox said at the tail end in the longitudinal direction of the steel plate and at the end in the width direction of the steel plate was because the temperature was higher than the temperature at the center in the longitudinal direction and the width direction of the steel plate.

However, regarding the tensile strength, the widthwise end of the thick steel plate and the longitudinal end of the thick steel plate are smaller than the center of the thick steel plate in the width direction. Although the lower limit of the allowable range was partially broken, the stripping camper was suppressed as compared with Comparative Examples 1 to 3, but was larger than Examples 1 to 3 of the present invention. Industrial applicability

According to the present invention, when controlled cooling of a rolled thick steel plate is performed, the temperature distribution in the plate surface of the thick steel plate is changed in the width direction and the thickness of the steel plate. It is possible to make the steel plate uniform over the entire area in the longitudinal direction of the steel plate, and to perform controlled cooling of a thick steel plate having a large cooling rate as a whole. As a result, it has become possible to ensure uniformity of the material in the width direction and the longitudinal direction of the steel plate, and to reduce distortion and residual stress during cooling.

table 1

 Cooling rate straightening

 Trailing end flow rate control Passing speed Temperature measurement value (width / longitudinal cooling device

 Use zone (mpm) (width · center of length) center)

 (° C) (° C / s) Preliminary control Preliminary preliminary control Preliminary control Cooling-in control Preliminary control Control cooling Preliminary cooling Control cooling

 Cooling Cooling Cooling Cooling Cooling Cooling In (Preliminary cooling out) Cooling out Cooling Cooling Invention example 1 Not used Not used Used Not used 1-2z Top and bottom Not used l ~ 4z One 134-751 543 One 31.0

 Only 3z below

 2- 2z top and bottom

Invention Example 2 Not used Not used Not used 44z-133-755 553-30.0

Only under 3z Not used l Inventive example 3 Not used Used All zones Not used All zones l ~ 2z 80 158 750 719 551 4.1 1 29.5 Inventive example 4 Used Used All zones Not used All zones l ~ 2z 80 158 753 723 552 4. 0 30.1 Comparative Example 1 Not used Not used Not used Not used Not used Not used ― 134-752 552 ― 29.8 Comparison Example 2 Not used 1 Not used Not used Not used Not used Not used Use 80 158 746 714 545 4.3 29.7 Comparative example 3 Not used Not used Not used Not used Not used Not used 42 ― 751 550-14.1-Comparative example 4 Not used Not used Not used All zones Not used All Zone not used 42 1 748 549 ― 13.9 ― Comparative Example 5 Not used Not used Not used All zones Not used All zones ― 134-753 550 ― 30.2

Table 2 Temperature drop amount

 (° C) No (mm; Tensile strength (MPa)

 End in the width direction End in the center in the width direction End in the longitudinal direction End of the tail end of the tail end of the tail end of the tail end of the tail Inventive example 1 -4 10 9 5 553 551 547 Inventive example 2-5 9 10 4 556 550 547 Invention example 3 3-7 7 4 551 549 553 Invention example 4 -1 5 3 2 549 555 546 Comparative example 1 31 49 90 21 549 620 650 Comparative example 2 52 74 157 32 548 630 610 Comparative Example 3 67 83 202 36 551 650 599 Comparative Example 4-30 -30 91 13 551 490 501 Comparative Example 5-40 -18 121 8 550 485 499

Claims

The scope of the claims

1. The first cooling step of cooling while making the temperature distribution in the width direction of the steel plate uniform

A second cooling step of controlling the entire width of the steel sheet in the width direction at the same cooling rate after the uniformization of the temperature distribution in the width direction of the steel sheet is completed. .

2. The first cooling step according to claim 1, wherein the first and second cooling steps include cooling at both ends in the width direction of the thick steel plate by one or more inlet cooling zones in a pass-type control cooling device having a plurality of independent cooling zones. Cooling while limiting the amount of water, the second cooling step is a hot rolling in which the entire width direction of the thick steel plate is controlled and cooled at the same cooling rate by a cooling zone subsequent to the one or more inlet-side cooling zones. Completed control cooling method of thick steel plate.

3. The method according to claim 1, wherein the first cooling step is performed by using a pre-cooling device to cool the steel plate while limiting the amount of cooling water at both lateral ends in the width direction,

 In the second cooling step, the whole thickness direction of the thick steel plate is controlled and cooled at the same cooling rate by a pass-type control cooling device having a plurality of independent cooling zones installed at a stage subsequent to the preliminary cooling device. Controlled cooling method for thick steel plate after hot rolling.

4. The thick steel plate according to any one of claims 1 to 3, wherein the cooling water amount at both ends in the width direction of the thick steel plate is limited by a shielding member installed at an end in the width direction of the thick steel plate. Control cooling method.

5. The method for controlling cooling of a thick steel plate according to any one of claims 2 and 4, wherein in the cooling of the control cooling device, the amount of cooling water at a longitudinal end of the thick steel plate is limited.

6. In any claim of claim 3 or 4, the pre-cooling device or the In the cooling of the pre-cooling device and the control cooling device, a controlled cooling method for a thick steel plate in which the amount of cooling water at a longitudinal end portion of the thick steel plate is limited.

7. In any claim of claim 5 or 6, the restriction of the amount of cooling water at the longitudinal end of the thick steel plate is limited by the amount of water that is activated for a predetermined time by the passing signal of the longitudinal end of the thick steel plate. A method for controlling and cooling a thick steel plate by a control means.

8. In any one of claims 2, 4, 5, and 7, the front part of the control cooling device has a width of a thick steel plate capable of limiting a water amount at an end in a width direction of the steel plate between each zone. The shielding member installed at the end is installed, and the shielding member controls the cooling water at the end in the width direction of the steel plate independently in each zone and the upper and lower surfaces.

9. In claim 8, the amount of temperature drop and the temperature drop at the plate edge in the width direction of the thick steel plate occur from the means for measuring the temperature distribution in the width direction of the thick steel plate before the controlled cooling and the measured temperature distribution. The distance from the end of the thick steel plate in the width direction is analyzed, and based on the results, the amount of shielding by the shielding members installed in each cooling zone in front of the control cooling device and the number of cooling zones to be shielded are calculated. And controlling the shielding member based on the calculated result.

10. In any of claims 3, 4, 6 and 7, the temperature distribution in the width direction is measured before pre-cooling, and from the measured temperature distribution, the end of the plate in the width direction of the thick steel plate is measured. The amount of temperature drop and the distance from the edge of the plate in the width direction where the temperature drop occurs are analyzed, and based on the results, the amount of shielding by the shielding member in the pre-cooling device and the cooling time are calculated. A controlled cooling method for thick steel plates that controls the shielding member and the passing speed of the pre-cooling device based on this.

11. A steel plate manufactured by controlled cooling according to the controlled cooling method according to claim 1 after hot rolling.

1 2. More independent a pass control cooling device having a cooling zone, the cooling zone is capable Rohm cooling water density is 1200L / min. M ² or more and steel plate in front of the cooling zone A controlled cooling device for thick steel plates, which is provided with shielding members that limit the amount of cooling water at both ends in the width direction.

13. A cooling device in which a pre-cooling device and a control cooling device are sequentially arranged on the rear surface of a rolling mill, wherein the pre-cooling device has an input water density of 500 L / min.m ² or less and a width direction of a thick steel plate. A shielding member for limiting the amount of cooling water at both side ends of the cooling zone is installed, and the control cooling device is a passage type device having a plurality of independent cooling zones, and the cooling water volume density of each cooling zone is 1200 L. /min.ni Controlled cooling system for thick steel plate that can pass water of ² or more

14. The controlled cooling device for a thick steel plate according to claim 12, wherein the operation of the shielding member is controlled so that a temperature distribution in a width direction of the thick steel plate is uniformed.

15. The controlled cooling device for a thick steel plate according to any one of claims 12 to 14, further comprising a water quantity control means that operates for a predetermined time in response to a passage signal at a longitudinal end portion and a tail end portion of the thick steel plate.

16. The control cooling device for a thick steel plate according to any one of claims 12, 14, and 15, wherein the control cooling device uses a slit jet cooling nozzle.

17. The control cooling device for a thick steel plate according to any one of claims 13, 14, and 15, wherein the preliminary cooling device is a laminar flow cooling nozzle, and the control cooling device is a slit jet cooling nozzle. .

18. In any one of claims 12, 14, 15, and 16, the shielding member provided between the cooling zones at the front stage of the control cooling device is provided for each cooling zone. [4] A thick steel plate controlled cooling device having a structure capable of blocking cooling water at an end portion in the width direction of the thick steel plate independently for each of an upper surface portion and a lower surface portion of the cooling zone.

19. In Claim 18, the temperature drop amount and temperature at the plate edge in the width direction of the thick steel sheet are obtained from the means for measuring the temperature distribution in the width direction of the thick steel sheet before controlled cooling and the measured temperature distribution. It has a means to analyze the distance from the plate edge in the width direction of the thick steel plate in which the descent occurs, and based on the result, the amount of shielding by the shielding members installed in each cooling zone in front of the control cooling device A controlled cooling device for a thick steel plate, having means for calculating the number of cooling zones for performing shielding, and having a mechanism for controlling the shielding member based on the calculated result.

20. The method according to any one of claims 13, 14, 15, and 17, wherein a means for measuring a temperature distribution in a width direction of the thick steel plate before cooling by the pre-cooling device is provided. Has a means to analyze the temperature drop at the plate edge in the width direction of the steel plate and the distance from the plate edge in the width direction of the steel plate where the temperature drop occurs, and based on the results, precooling Control cooling device for thick steel plate with means for calculating the amount of shielding by the shielding member of the device and the cooling time, and having a mechanism that can control the shielding member and the passing speed in the pre-cooling device based on the calculated results

21. The control cooling device for a thick steel plate according to any one of claims 12, 14, 15, 15, 16, 18, and 19, wherein a straightening machine is installed before the control cooling device.

22. In any one of claims 13, 14, 15, 15, 17 and 20, the controlled cooling of a thick steel plate in which a straightening machine is installed between the preliminary cooling device and the control cooling device. Device.