CN115156314A - Cooling device and cooling method for thick steel plate, and thick steel plate manufacturing facility and manufacturing method - Google Patents
Cooling device and cooling method for thick steel plate, and thick steel plate manufacturing facility and manufacturing method Download PDFInfo
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- CN115156314A CN115156314A CN202210684880.3A CN202210684880A CN115156314A CN 115156314 A CN115156314 A CN 115156314A CN 202210684880 A CN202210684880 A CN 202210684880A CN 115156314 A CN115156314 A CN 115156314A
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- 238000001816 cooling Methods 0.000 title claims abstract description 420
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 177
- 239000010959 steel Substances 0.000 title claims abstract description 177
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 21
- 239000000498 cooling water Substances 0.000 claims abstract description 87
- 239000007921 spray Substances 0.000 claims description 59
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 51
- 238000002347 injection Methods 0.000 claims description 32
- 239000007924 injection Substances 0.000 claims description 32
- 230000001105 regulatory effect Effects 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 21
- 238000005507 spraying Methods 0.000 claims description 14
- 230000000452 restraining effect Effects 0.000 claims description 6
- 238000007664 blowing Methods 0.000 claims description 5
- 239000011295 pitch Substances 0.000 description 28
- 238000010438 heat treatment Methods 0.000 description 16
- 238000010791 quenching Methods 0.000 description 9
- 230000000171 quenching effect Effects 0.000 description 9
- 230000001276 controlling effect Effects 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 239000002131 composite material Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- 238000010583 slow cooling Methods 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 238000003303 reheating Methods 0.000 description 2
- 229910001563 bainite Inorganic materials 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/62—Quenching devices
- C21D1/667—Quenching devices for spray quenching
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
- B21B45/0203—Cooling
- B21B45/0209—Cooling devices, e.g. using gaseous coolants
- B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
- B21B45/0233—Spray nozzles, Nozzle headers; Spray systems
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/38—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling sheets of limited length, e.g. folded sheets, superimposed sheets, pack rolling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
- C21D1/60—Aqueous agents
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D11/00—Process control or regulation for heat treatments
- C21D11/005—Process control or regulation for heat treatments for cooling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/54—Furnaces for treating strips or wire
- C21D9/56—Continuous furnaces for strip or wire
- C21D9/573—Continuous furnaces for strip or wire with cooling
- C21D9/5735—Details
- C21D9/5737—Rolls; Drums; Roll arrangements
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/38—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling sheets of limited length, e.g. folded sheets, superimposed sheets, pack rolling
- B21B2001/386—Plates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
- B21B37/76—Cooling control on the run-out table
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
- B21B45/0203—Cooling
- B21B45/0209—Cooling devices, e.g. using gaseous coolants
- B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
- B21B45/0218—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes for strips, sheets, or plates
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatments In General, Especially Conveying And Cooling (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Abstract
The application provides a cooling device and a cooling method for a thick steel plate, and a manufacturing device and a manufacturing method for the thick steel plate. In a thick steel plate cooling device, the ratio P/D of a limiting roll pitch P to a limiting roll diameter D is set to be 2.0 to 2.5, a plurality of cooling headers are arranged between limiting rolls, each cooling header is connected to one of two or more cooling water supply systems, each cooling header has a plurality of cooling nozzles along the width direction of a steel plate, the cooling nozzles adjacent to each other along the width direction of the steel plate are connected to the cooling headers of different cooling water supply systems, and the flow density of cooling water sprayed from the cooling nozzles adjacent to each other along the width direction of the steel plate is set to be different.
Description
The present application is a divisional application of an invention patent application having an application date of 2018, 12 and 14 months, and an application number of 201880081519.3, entitled "cooling device and cooling method for thick steel plate, and manufacturing equipment and manufacturing method for thick steel plate".
Technical Field
The present invention relates to a cooling apparatus and a cooling method capable of controlling a shape and adjusting a cooling rate in a wider range than a conventional cooling apparatus and cooling method in a case where controlled cooling after hot rolling or cooling by reheating quenching is performed on a steel sheet cooled to room temperature after hot rolling in a thick steel sheet manufacturing line. The present invention also relates to a thick steel plate manufacturing facility using the cooling apparatus and a thick steel plate manufacturing method using the cooling method.
Background
In particular, in the production of thick steel plates (also referred to simply as steel plates), it is necessary to ensure mechanical properties required for steel plates, particularly strength and toughness. In order to achieve this, the hot rolled thick steel plate is cooled as it is, or is air-cooled to room temperature once and then reheated and quenched offline. In this cooling operation, cooling is often performed at a high cooling rate, because of the properties required of the steel sheet in terms of material, particularly, the strength.
On the other hand, due to recent advanced material control, not only the demand for higher strength is increasing, but also the demand for a composite structure of a soft phase change structure and a hard phase change structure is increasing. For example, there is a method of obtaining a composite structure such as ferrite + bainite or ferrite + martensite by setting a relatively slow cooling rate in the initial stage or the later stage of cooling. By forming the composite structure, for example, a steel sheet or the like having a reduced yield ratio, which is a ratio of yield strength to tensile strength, and excellent vibration resistance can be manufactured.
Conventionally, in order to achieve such composite structure in a thick steel plate, a multi-stage heat treatment in which reheating quenching is performed a plurality of times has been performed, but in order to save the number of steps, a cooling technique capable of changing the cooling rate at an arbitrary timing in one quenching has been demanded. In particular, in order to promote the generation of ferrite, it is necessary to perform cooling at an extremely slow cooling rate (for example, about 2 to 20 ℃/s) for a long time. Therefore, it is required to adjust the cooling rate to an extremely low level as compared with the cooling rate (about 30 to 60 ℃/s in the case of a plate thickness of 20 mm) of a general on-line controlled cooling apparatus or a quenching apparatus in heat treatment.
As a technique for changing the cooling rate at an arbitrary timing during the cooling of the thick steel plate, there are the following patent documents.
Patent document 1 discloses a technique of changing the cooling capacity in a wide range by changing the liquid level of a water tank by arranging the water tank and a nozzle provided in the water tank, with respect to the following cooling manifold. In patent document 1, when the cooling capacity is improved, the liquid level of the water tank is raised to immerse the tip of the nozzle in water, and the water in the water tank is accompanied by the sprayed water in addition to the sprayed cooling water, so that the steel sheet can be subjected to a larger amount of water than the sprayed flow rate of the nozzle. In addition, when the cooling capacity is reduced, the liquid level of the water tank is reduced to avoid the nozzle tip from being submerged in the water, and the accompanying flow described above is avoided from being generated, so that the steel sheet can be subjected to a small amount of water. On the other hand, in such a technique, since a water tank needs to be disposed between the roller bed rollers, cooling is limited to the lower surface of the steel plate, and cannot be used for cooling the upper surface. In addition, in a facility having a narrow roller bed roller gap such as a quenching apparatus for a thick plate, it is not possible to provide a water tank between rollers.
Therefore, patent document 3 describes the following technique for improving the above-mentioned point: a rapid cooling device and a slow cooling device having rod-shaped cooling water nozzles with different flow rate characteristics are arranged in front of and behind each other, and the rapid cooling device and the slow cooling device are switched in one cooling area to perform injection, thereby adjusting the cooling speed in a wide range.
Prior art documents
Patent document
Patent document 1: japanese laid-open patent publication No. 59-47010
Patent document 2: japanese patent laid-open publication No. 2014-124634
Patent document 3: japanese patent laid-open publication No. 2011-167759
Disclosure of Invention
Problems to be solved by the invention
In cooling of a thick steel plate, particularly in off-line heat treatment, so-called roll quenching is often used in which the steel plate is cooled by passing the steel plate through rollers while being restricted by the rollers. This form is widely used because the steel sheet is cooled while being restrained by the rollers, and therefore the flatness of the steel sheet after cooling is good, and the subsequent shape correction processing can be reduced. On the other hand, since the roll quenching uses rolls having a relatively large diameter in order to improve the cooling shape and restricts the steel sheet at a narrow roll pitch, it is not possible to secure a large space for a cooling device provided between the rolls. Therefore, it is difficult to apply the technique of patent document 3 to a roll quenching type cooling device.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a cooling apparatus and a cooling method effective for a narrow cooling space in a roll quenching type cooling apparatus in which a cooling rate can be adjusted over a wide range by adjusting the amount of cooling water over a wide range while controlling the shape of a thick steel plate, and in particular, a cooling apparatus is provided between thick steel plate-regulating rolls. Further, an object of the present invention is to provide a thick steel plate manufacturing facility using the cooling apparatus and a thick steel plate manufacturing method using the cooling method.
Means for solving the problems
As a result of extensive studies, the inventors have found that the shape of the steel sheet can be controlled by setting the ratio P/D of the limiting roll pitch P to the limiting roll diameter D to a predetermined range, and that the cooling rate can be adjusted in a wide range by using cooling nozzles having different flow densities.
The gist of the present invention is as follows.
[1] A cooling device for a thick steel plate, comprising a plurality of restricting rolls arranged in a steel plate conveying direction and a plurality of cooling headers arranged between the restricting rolls,
the ratio P/D of the restricting roller pitch P to the restricting roller diameter D is set to 2.5 or less,
each cooling header is connected to any one of two or more cooling water supply systems,
each cooling water supply system is provided with a regulating valve which can independently perform opening and closing of water supply and flow control,
a plurality of cooling nozzles are installed in each cooling header in the width direction of the steel sheet,
the cooling nozzles adjacent in the steel sheet width direction are connected to the cooling headers of different cooling water supply systems, respectively, and,
the flow density of the cooling water sprayed from the cooling nozzles adjacent in the steel sheet width direction is set to be different flow densities, and the cooling water having a flow density three times or more as high as that of the cooling water sprayed from the cooling nozzle spraying the cooling water having the smallest flow density can be sprayed from the cooling nozzle spraying the cooling water having the largest flow density for the same spray pressure,
the cooling device for a thick steel plate is provided with a control means that controls the cooling device using a control valve so as to individually select each cooling water supply system and spray cooling water from a cooling nozzle.
[2] The thick steel plate cooling apparatus according to [1], wherein the distance from the tip of each cooling nozzle to the steel plate is set to a position within a range of ± 50mm or less with respect to the height of the restraining roll center axis.
[3] The thick steel plate cooling apparatus according to [1] or [2], wherein each cooling nozzle is one or more of a flat nozzle, a full cone nozzle, a square spray nozzle, and an elliptical spray nozzle, and an injection angle of the cooling water when the cooling water is injected from each cooling nozzle is in a range of 60 to 120 °.
[4] A cooling method for a thick steel plate, using a cooling apparatus in which a plurality of restricting rolls are provided in a steel plate conveying direction and a plurality of cooling headers are arranged between the restricting rolls,
the ratio P/D of the restricting roller pitch P to the restricting roller diameter D is set to 2.5 or less,
each cooling header is connected to any one of two or more cooling water supply systems,
each cooling water supply system is provided with a regulating valve which can independently control the opening and closing of the water supply and the flow rate,
a plurality of cooling nozzles are installed in each cooling header in the width direction of the steel sheet,
the cooling nozzles adjacent in the width direction of the steel sheet are connected to the cooling headers of different cooling water supply systems, respectively, and,
the flow density of the cooling water sprayed from the cooling nozzles adjacent in the steel sheet width direction is set to be different flow densities, and the cooling water having a flow density three times or more as high as that of the cooling water sprayed from the cooling nozzle spraying the cooling water having the smallest flow density can be sprayed from the cooling nozzle spraying the cooling water having the largest flow density for the same spray pressure,
the control is performed using a control valve so that each cooling water supply system is individually selected and cooling water is injected from the cooling nozzle.
[5] The method of cooling a thick steel plate according to item [4], wherein the distance from the tip of each cooling nozzle to the steel plate is set to a position in a range of ± 50mm or less with respect to the height of the restriction roll center axis.
[6] The method for cooling a thick steel plate according to [4] or [5], wherein each of the cooling nozzles is one or more of a flat nozzle, a full cone nozzle, a square spray nozzle, and an elliptical spray nozzle, and an injection angle of the cooling water when the cooling water is injected from each of the cooling nozzles is in a range of 60 to 120 °.
[7] A thick steel plate manufacturing facility comprising the cooling device according to any one of [1] to [3 ].
[8] A method for manufacturing a thick steel plate, comprising a step of cooling by the cooling method according to any one of [4] to [6 ].
Effects of the invention
According to the present invention, in cooling a thick steel plate, the shape can be controlled and the cooling rate can be adjusted over a wide range, and thick steel plates having various strengths can be manufactured. In addition, the technique is effective particularly in a narrow cooling space in which a cooling device is provided between the regulating rollers provided at a narrow pitch in the conveyance direction.
Drawings
FIG. 1 is a schematic view of an off-line heat treatment facility for thick steel plates using the cooling apparatus of the present invention.
Fig. 2 is a schematic view showing an embodiment of a cooling apparatus according to the present invention.
Fig. 3 is a diagram illustrating a positional relationship between the cooling nozzle and the restricting roller according to the present invention.
Fig. 4 is a view showing the spray angle of cooling water (spray water) sprayed from the cooling nozzle.
Fig. 5 is a schematic view of the cooling apparatus of the present invention as viewed from above, fig. 5 (a) is a view showing the structure of the cooling header, and fig. 5 (b) and (c) are views showing the state of spray water sprayed from the cooling nozzles.
Fig. 6 is a diagram showing the arrangement of the cooling headers and the cooling nozzles when a system of the cooling headers is made into a plurality of systems (four systems).
Fig. 7 is a view showing a state where spray water from the small-flow cooling nozzles collides with the thick steel plate when the cooling water is sprayed from the cooling headers of the two systems, and fig. 7 (a) shows a case where the flat nozzles are used, fig. 7 (b) shows a case where the elliptical nozzles are used, fig. 7 (c) shows a case where the full cone nozzles are used, and fig. 7 (d) shows a case where the square spray nozzles are used.
Fig. 8 is a schematic view of a case where the nozzle pitch is different between the large-flow cooling nozzle and the small-flow cooling nozzle, fig. 8 (a) is a view showing the structure of the cooling header, fig. 8 (b) is a view showing a case where water is sprayed from the large-flow cooling nozzle, and fig. 8 (c) is a view showing a case where water is sprayed from the small-flow cooling nozzle.
Fig. 9 is a schematic view of a cooling apparatus for thick steel plates using the cooling device of the present invention.
Fig. 10 is a graph showing a relationship between injection pressure and flow density in the large-flow cooling nozzle and the small-flow cooling nozzle.
Fig. 11 is a graph showing the relationship between the cooling rate and the flow density from 800 ℃ to 400 ℃ at the center in the thickness direction when the steel sheet is cooled.
Detailed Description
Embodiments of the present invention will be described based on the drawings.
Fig. 1 is a diagram illustrating a case where the cooling apparatus of the present invention is applied to off-line heat treatment of a thick steel plate. The thick steel plate S is processed in advance to a predetermined thickness (for example, 40 mm) and width (for example, 2500 mm) by a rolling mill, transferred to a main heat treatment line, heated to a predetermined temperature (for example, 920 ℃) by a heating furnace 1, and cooled by a cooling device 2 provided on the output side of the heating furnace 1. The cooling device 2 is composed of roller rolls 3 for conveying the thick steel plate S, regulating rolls 4 for regulating the thick steel plate S, and cooling headers 5 provided on the upper and lower surfaces of the thick steel plate S.
Fig. 2 shows a cooling device 2 according to an embodiment of the present invention in detail. As shown in fig. 2, a plurality of roller rollers 3 for conveying the thick steel plate S and a plurality of regulating rollers 4 for regulating the thick steel plate S are provided, and a plurality of large-flow cooling headers 51 and a plurality of small-flow cooling headers 52 are provided on the upper and lower surfaces (between the roller rollers 3) between the regulating rollers 4. In each cooling header, the flow rate of the cooling water supplied to the cooling header is measured by a flow meter 6, and a flow rate adjustment valve 7 is provided so as to be adjustable to a predetermined flow rate based on the measurement result. The flow rate adjustment valve 7 is connected to a control mechanism (not shown), and can be individually set to open and close (supply/shut-off) the cooling water. A plurality of cooling nozzles 53 (54) are attached to each cooling header. The cooling nozzle 53 (54) will be described in detail later.
Hereinafter, the positional relationship between the cooling header (cooling nozzle) on the upper surface of the thick steel plate and the regulating roller 4 will be described. The roller table roller 3 and the regulating roller 4 are spaced at the same distance. Therefore, the positional relationship between the cooling header (cooling nozzle) on the lower surface of the thick steel plate and the roller table rollers 3 is the same as the positional relationship between the cooling header (cooling nozzle) on the upper surface of the thick steel plate and the regulating rollers 4.
Fig. 3 is a diagram illustrating a positional relationship between the cooling nozzle and the restricting roller according to the present invention. In the present invention, application to thick steel plates is mainly considered, and prevention of out-of-plane deformation occurring when thick steel plates are cooled is an important issue. Therefore, in order to prevent the out-of-plane deformation, the thick steel plate S is cooled while being restricted by the restricting roll 4 and the roller roll 3. In this case, the setting pitch of the regulating rollers 4 with respect to the conveying direction (the regulating roller pitch P) is as narrow as possible, which is advantageous in terms of preventing out-of-plane deformation of the steel sheet. Further, the restriction roller 4 is preferably restricted to have the roller diameter D as large as possible in order to reduce the deflection of the restriction roller 4 even if a large load is applied, from the viewpoint of appropriately preventing out-of-plane deformation. On the other hand, the narrower the regulating roll pitch P of the regulating rolls 4 is, the narrower the inter-roll gap G is, and thus the smaller the space for installing the cooling device 2 is. Therefore, particularly in the case of a nozzle requiring a large cooling manifold as described in patent document 3, it is impossible to provide a cooling device as in the present invention. From the viewpoint of uniform cooling, in order to cool the steel plate S to the vicinity of the contact point between the restricting roll 4 and the steel plate S, it is preferable that the spray length L of the cooling nozzle 53 (or the cooling nozzle 54) when viewed from the side is larger than the inter-roll gap G and the steel plate S is subjected to cooling water to the region below the restricting roll 4. From such a viewpoint, a system capable of spraying cooling water over a wide area, such as spray cooling, is also preferable.
In view of the above points, the present inventors have conducted extensive studies and as a result, from the viewpoint of controlling the shape of the steel sheet, the ratio P/D of the restricting roll pitch P of the restricting roll 4 to the restricting roll diameter D is set to be 2.5 or less. When the P/D is 1.0, the restricting roll pitch is the same as the diameter of the restricting roll, and there is no gap between the front and rear restricting rolls, and thus a cooling nozzle cannot be provided. Therefore, P/D is preferably more than 1.0, and the clearance (P-D) between the front and rear regulating rolls can be ensured to be at least 50 mm. Therefore, from the viewpoint of handling, the P/D is more preferably 1.17 or more. Further, since it is preferable that the P/D is as small as possible from the point of shape control, it is preferable that the P/D is 2.0 or less.
The roller diameter of the roller bed roller 3 and the limiting roller diameter D do not have to be the same diameter. In the case where the roll diameter of the roller table roll 3 is the same as or different from the limiting roll diameter D, the ratio P/D may be 2.5 or less as described above on the upper and lower surfaces of the thick steel plate. The roller pitch and the roller diameter of the roller rollers 3 on the lower surface of the thick steel plate may be set to a ratio of 2.5 or less.
In addition, when the spray length L of the cooling nozzle 53 (54) in the conveyance direction is as close as possible to the limiting roller pitch P between the limiting rollers 4, the number of non-cooling portions between the limiting rollers 4 is reduced, and effective cooling can be performed. Therefore, the spray length L is preferably at least longer than the inter-roller interval G. On the other hand, in order to increase the spray length L, the spray angle θ of the cooling nozzle 53 (54) shown in fig. 4 needs to be increased. At this time, if the spray angle θ of the cooling nozzles 53 (54) is excessively increased, or if the cooling nozzles 53 (54) are provided in a state in which the nozzle center axes of the cooling nozzles 53 (54) are offset in the conveyance direction (the left and right direction in the drawing) from the center position between the restricting rolls 4, the spray water 55 (56) from the cooling nozzles 53 (54) collides with the restricting rolls 4 before colliding with the thick steel plate S, and there is a possibility that the thick steel plate S cannot be cooled efficiently. Therefore, it is preferable to select an appropriate spray angle θ, and the nozzle center axis of the cooling nozzle 53 (54) is preferably arranged within ± 10mm from the center position between the restriction rollers 4 with respect to the conveyance direction (the left and right direction in the drawing), and most preferably substantially at the center position between the restriction rollers 4.
Next, the cooling header of the cooling device 2 will be explained. Fig. 5 (a) is a schematic view of the cooling apparatus 2 of the present invention viewed from above, and is a view illustrating the structure of the cooling header. A plurality of large-flow cooling nozzles 53 are attached to the large-flow cooling header 51 in the steel sheet width direction. On the other hand, a plurality of small-flow cooling nozzles 54 are attached to the small-flow cooling header 52 in the steel sheet width direction.
In the present invention, the cooling nozzles are arranged at different flow rates per unit area and per unit time. Here, the flow rate of the cooling water sprayed in the range of the interval P' between adjacent cooling nozzles is defined as the unit area and the unit time. Hereinafter, the flow rate per unit area and per unit time is referred to as the flow rate density (unit: L/(min m) 2 ))。
That is, as shown in fig. 5 (a), cooling nozzles of large flow rate density are mounted on the large flow rate cooling header 51, and cooling nozzles of small flow rate density are mounted on the small flow rate cooling header 52, so that cooling nozzles adjacent in the width direction are connected to cooling headers of different systems, respectively.
In the present invention, the cooling nozzles having different flow densities are arranged adjacent to each other in the width direction. The large-flow cooling nozzles 53 and the small-flow cooling nozzles 54 may be arranged in a row at a predetermined pitch in the width direction of the thick steel plate S.
In the present invention, when the cooling rate of the steel sheet is increased, in order to avoid the injection of the cooling water from the small flow rate cooling nozzle 54, the water supply to the small flow rate cooling header 52 is shut off by the flow rate adjustment valve 7, and the cooling water is injected from the large flow rate cooling nozzle 53. On the other hand, when the cooling rate is decreased, in order to avoid the cooling water from being injected from the large flow rate cooling nozzle 53 by the flow rate adjustment valve 7, the water supply to the large flow rate cooling header 51 is shut off by the flow rate adjustment valve 7, and the cooling water is injected from the small flow rate cooling nozzle 54. That is, in the present invention, the flow rate can be adjusted over a wide range by selecting each cooling water supply system individually and injecting cooling water, and the cooling rate can be adjusted over a wide range.
In general, when a nozzle having a certain characteristic is selected and cooling water is injected from the nozzle, the flow rate of the cooling water is proportional to the injection pressure to the power of 0.5, and therefore, even if the injection pressure is lowered, the change in the flow rate is small, and it is very difficult to change the cooling rate greatly. Generally, it can be said that the cooling rate is proportional to about 0.7 th power of the flow density. Thus, the cooling rate is proportional to about 0.35 power of the injection pressure.
Thus, for example, when the cooling rate is about half, the injection pressure needs to be reduced to about 1/7. In a general flow rate adjustment valve, since the injection pressure can be adjusted to a range of about 10 to 100% of the rated pressure, the adjustment of the cooling capacity to about 50 to 100% at the maximum becomes a substantial limit. Since the injection flow rate is proportional to the injection pressure to the power of 0.5, the adjustment of the injection flow rate to the range of 31.6 to 100% is limited when it is considered that the injection pressure can be adjusted to the range of about 10 to 100% as described above. Therefore, in the present invention, the cooling speed can be adjusted in a wide range by disposing the cooling nozzles having different flow densities between the restrictor rollers 4.
In the present invention, the flow density of the cooling water sprayed from the cooling nozzles adjacent in the steel sheet width direction is set to be different, and the cooling water having a flow density 3 times or more higher than that of the cooling nozzle spraying the cooling water having the smallest flow density can be sprayed from the cooling nozzle spraying the cooling water having the largest flow density for the same spray pressure. In fig. 5 (a), the flow density of the large flow rate cooling nozzles 53 arranged at intervals of the pitch P' is at least 3 times or more the flow density of the small flow rate cooling nozzles 54 with respect to the same injection pressure.
Next, a specific method of selecting the cooling nozzles will be described by taking a case where the cooling water is injected from the cooling header of the dual system as an example.
The large flow rate cooling nozzle 53 and the small flow rate cooling nozzle 54 are arranged in the width direction of the steel plateWhen the nozzle pitch is the same and cooling water is injected at a pressure of 0.4MPa, the flow density of the large-flow cooling nozzle 53 is selected to be 1500L/(min m.m) 2 ) The flow density of the small-flow cooling nozzle 54 is set to 500L/(min. M) 2 ). With such a configuration, the flow rate density of the large flow rate cooling nozzle 53 can be adjusted to 500L/(min · m) by further controlling the flow rate using the flow rate adjusting valve 7 2 ) (1/3 of the rated flow rate), the flow rate density of the small flow rate cooling nozzle 54 was adjusted to 167L/(min m) 2 ) (nominally 1/3). Therefore, the maximum flow density of the cooling nozzle from the large flow rate can be 1500L/(min m) by switching the flow rate control and the cooling nozzle 2 ) Minimum flow density to the Low flow Cooling nozzle 167L/(min m) 2 ) The flow rate is continuously adjusted. In the case where adjustment such as continuous change of the flow density of the large-flow-rate cooling nozzles and the small-flow-rate cooling nozzles 54 is not necessary in the production of the steel sheet as described above, the maximum flow density of the small-flow-rate cooling nozzles 54 does not need to be the same as the minimum flow density of the large-flow-rate cooling nozzles 53, and for example, the maximum flow density of the large-flow-rate cooling nozzles 53 may be set to 1500L/(min · m) 2 ) The maximum flow density of the small-flow cooling nozzle 54 is set to 50L/(min m) 2 ) Such a selection.
In this way, by selecting one cooling header of the system by the flow rate adjustment valve 7 and spraying the cooling water from the cooling nozzles, the amount of spray water can be continuously adjusted over a wide range.
In the present invention, since the cooling nozzles having different flow densities are arranged adjacent to each other and only one of them is sprayed, for example, in fig. 5 (b) and 5 (c), in the case of the flat spray shape in which spray water is sprayed in a fan shape, the spray angle θ (see fig. 4) and the twist angle α (see fig. 5 (c)) are set so that the width end of spray water 55 sprayed from the large-flow cooling nozzle 53 is substantially the same position as the adjacent spray water 55 in fig. 5 (b), and thus, when a steel sheet is cooled, a portion where cooling water does not collide with the steel sheet does not occur in the width direction when viewed from the steel sheet side, and the steel sheet can be uniformly cooled.
In the case of fig. 5 c as well, by providing the spray angle θ (see fig. 4) and the twist angle α (see fig. 5 c) so that the width end of the spray water 56 sprayed from the small flow rate cooling nozzle 54 is positioned at substantially the same position as the adjacent spray water 56, when the steel sheet is cooled, the steel sheet can be uniformly cooled without generating a portion where the cooling water does not collide with the steel sheet in the width direction when viewed from the steel sheet side.
As the spray angle θ of the cooling nozzles (the large flow rate cooling nozzles 53 or the small flow rate cooling nozzles 54), it is preferable to provide the cooling nozzles between the narrow restricting rolls 4 and to receive the steel sheet so as to avoid collision of the sprayed cooling water with the restricting rolls 4, and thus it is preferable to spread the cooling water at as wide an angle as possible. In the present invention, the spray angle θ (see fig. 4) of the cooling nozzle is preferably at least 60 to 120 °. When the spray angle θ is less than 60 °, the cooling water cannot be spread over a large area, and thus there may be temperature unevenness caused by non-collision portions of the cooling water. On the other hand, when the spray angle is larger than 120 °, the flight distance from the sprayed water to the steel sheet greatly varies from the flight distance to the nozzle to the other portions, and thus it is difficult to ensure the uniformity of cooling.
Further, the distance (nozzle height H) from the tip of the cooling nozzle to the steel sheet will be described with reference to fig. 3. Regarding the distance between the cooling nozzle (the large flow rate cooling nozzle 53 or the small flow rate cooling nozzle 54) and the thick steel sheet S, when considered from the point of collision between the restricting roll 4 and the spray water, the closer the cooling nozzle tip is to the steel sheet, the more the cooling water is difficult to collide with the restricting roll 4 even if sprayed at a large spray angle θ. In particular, when the distance between the cooling nozzle and the thick steel plate S is larger than half of the restricting roll diameter D at which the gap between the restricting rolls 4 is the narrowest, the spray water from the cooling nozzle easily collides with the restricting rolls 4 at the minimum gap portion between the restricting rolls 4. Therefore, the distance between the cooling nozzle and the thick steel plate S is preferably as short as possible as a position lower than the vicinity of half (radius) of the limiting roll diameter D. On the other hand, when the distance between the tip of the cooling nozzle and the thick steel plate S is short, the spray water must be sprayed at a large angle, and the spray angle θ described above may exceed 120 °. Further, there is also a risk that the tip of the steel plate in the through plate collides with the tip of the cooling nozzle. In practical use from both points of view, when cooling a thick steel plate, the distance H from the tip of each cooling nozzle to the steel plate is preferably a distance from the central axis of the restraining roll to the steel plate on the upstream and downstream sides with respect to the steel plate conveying direction of the nozzle, and the tip of the nozzle is provided at a position within ± 50mm in height from the central axis of the restraining roll.
In the above, the example in which the cooling rate is adjusted by the flow density of the two systems of the large flow rate cooling nozzle 53 and the small flow rate cooling nozzle 54 has been described, but the present invention can be applied to only two or more systems. For example, as shown in fig. 6, the cooling rate may be adjusted in a wider range by changing the system of the cooling header into a plurality of systems (four systems).
In fig. 6, medium flow rate cooling headers 57 and 58 are arranged in addition to the large flow rate cooling header 51 to which the plurality of large flow rate cooling nozzles 53 are attached in the steel sheet width direction and the small flow rate cooling header 52 to which the plurality of small flow rate cooling nozzles 54 are attached in the steel sheet width direction. A plurality of medium flow rate cooling nozzles 59 and 60 are attached to the medium flow rate cooling headers 57 and 58, respectively, in the steel sheet width direction.
As a specific method of selecting the cooling nozzles in the case of FIG. 6, when spraying is performed at a pressure of 0.4MPa with the same nozzle pitch in the width direction of each cooling nozzle, the flow density of the large-flow cooling nozzle 53 is set to 1500L/(min m) 2 ) The flow density of the medium flow cooling nozzle 59 was set to 150L/(min. M) 2 ) The flow density of the medium flow cooling nozzle 60 was set to 40L/(min m) 2 ) The flow density of the small-flow cooling nozzle 54 was set to 10L/(min m) 2 ) The method of (a). Thus, the difference in flow density of at least 3 times or more is set for the same injection pressure in the cooling nozzle with the maximum flow density and the cooling nozzle with the minimum flow density. With such a configuration, the flow rate can be continuously controlled by further controlling the flow rate using the flow rate control valve 7A wide range of adjustments in cooling rate are made.
In the present invention, each cooling nozzle is preferably any one or more of a flat nozzle, a full cone nozzle, a square blowing nozzle, and an elliptical blowing nozzle.
The spray angle of each cooling nozzle is an angle at which the spray angle becomes the widest in each direction when the spray water is viewed from the side. Fig. 7 is a view of cooling nozzle 53 (54) from above showing spray water 55 (56) colliding with a thick steel plate. Fig. 7 (a) shows a flat nozzle which is ejected in a substantially fan shape and has a small thickness (about 20 mm) and a wide collision surface, and fig. 7 (b) shows an example of an elliptical nozzle in which the collision surface is elliptical. When the collision surface of the cooling water is in an elliptical shape, such as a flat nozzle or an elliptical nozzle, the angle of the collision surface extending in the major axis direction is the widest angle as shown in fig. 7 (a) and (b), and therefore the angle may be set as the injection angle. In the full cone nozzle having a circular collision surface as shown in fig. 7 (c), the ejection angle is the same in any direction when viewed from the side. In the case of a square-shaped blowing nozzle or the like having a rectangular (square or rectangular) collision surface as shown in fig. 7 d, the angle extending in the diagonal direction of the collision surface is the widest angle, and therefore the angle may be set as the ejection angle.
As shown in fig. 8, the mounting pitches of the nozzles in the width direction of the large flow rate cooling nozzle 53 and the small flow rate cooling nozzle 54 may be different from each other. Fig. 8 (a) is a view showing a structure of the cooling header when the mounting pitch of the small flow rate cooling nozzles 54 is 2 times the mounting pitch of the large flow rate cooling nozzles 53 in the width direction, fig. 8 (b) is a view showing a state in which the large flow rate nozzles 53 spray water, and fig. 8 (c) is a view showing a state in which the small flow rate cooling nozzles 54 spray water. In fig. 8 (b) and (c), all the nozzles are flat nozzles. For example, in the case where the flow density of the large flow rate cooling nozzle 53 is 4 times the flow density of the small flow rate cooling nozzle 54 as an example where the flow density is more than 3 times, when spraying is performed at a pressure of 0.4Mpa, large flow rate cooling is performedThe maximum flow density of the nozzle 53 was 1500L/(min. M) 2 ) The minimum flow density of the small-flow cooling nozzle 54 is 375L/(min m) 2 )。
The large-flow cooling nozzle 53 and the small-flow cooling nozzle 54 may be provided in different spray forms.
As described above, the example of the off-line heat treatment process of the thick steel plate is explained, but it is needless to say that the slab may be heated by the heating furnace 1 and then rolled to a predetermined size by the rolling mill 8, and then cooled by the cooling device 2 including the cooling header 5 between the regulating rolls 4 as in the present invention, as shown in fig. 9. In order to smoothly convey the thick steel sheet S immediately after rolling to the cooling device 2, it is preferable to convey the steel sheet S to the cooling device 2 after flattening the steel sheet by the hot straightening machine 9.
The cooling device of the present invention can be preferably used for a thick steel plate having a plate thickness of 4.0mm or more and a plate width of 100mm or more.
Therefore, if the manufacturing facility of the thick steel plate is provided with the cooling device of the present invention, the shape of the thick steel plate can be controlled and the cooling rate can be adjusted in a wide range, so that thick steel plates having various strengths can be manufactured. Further, according to the cooling method of the present invention, since the thick steel plate can be cooled at a wide range of cooling rates while controlling the shape of the thick steel plate, thick steel plates having various strengths can be manufactured if the manufacturing method includes the step of cooling the thick steel plate by the cooling method of the present invention.
Example 1
As a first example of the present invention, a thick steel plate was manufactured using an off-line heat treatment apparatus for a thick steel plate shown in fig. 1. After a steel sheet (thickness 25mm, sheet width 3500mm, steel sheet length 7 m) in a room temperature state was heated to 920 ℃ in the heating furnace 1, the steel sheet was cooled by adjusting the passing speed so that the steel sheet temperature became 100 ℃ in the cooling apparatus 2 located 2.5m behind the heating furnace 1. In the same manner as in fig. 2, the cooling device 2 has a structure in which the diameters of the roller bed rollers 3 and the regulating rollers 4 are set to 300mm, the roller pitch P between the roller bed rollers 3 and the regulating rollers 4 is set to 600mm, and the cooling nozzles 53 and 54 are provided between the regulating rollers 4 (P/D = 2.0). The cooling nozzles 53 and 54 and the restricting roller 4 were provided at 15 stages in the steel sheet conveyance direction (the length of the cooling device 2 was 9.0 m).
The arrangement of the cooling nozzles 53 and 54 is the same as that of fig. 3, and the distance between the cooling nozzles and the steel sheet is 200mm. The large-flow cooling nozzle 53 is a flat nozzle that injects at an injection pressure of 0.4Mpa and 150L/min. The injection angle θ of the large flow rate cooling nozzles 53 is 100 °, the width direction pitch P' of the adjacent large flow rate cooling nozzles 53 is 160mm, and the twist angle α is 48 ° in the steel sheet traveling direction. At this time, the flow density of the large flow rate cooling nozzle 53 at an injection pressure of 0.4MPa was 1563L/(min m) 2 ). The small flow rate cooling nozzle 54 was a flat nozzle that injected at an injection pressure of 0.4MPa and 40L/min. The spray angle θ of the small flow rate cooling nozzle 54 is 100 °, the width direction pitch P' of the adjacent small flow rate cooling nozzles 54 is 160mm, and the twist angle α is 48 ° in the steel sheet traveling direction. At this time, the flow density of the small flow rate cooling nozzle 54 at an injection pressure of 0.4MPa was 417L/(min m) 2 )。
Fig. 10 is a graph showing the relationship between the injection pressure and the flow density of the large flow rate cooling nozzle 53 and the small flow rate cooling nozzle 54.
First, when water is passed through the large flow rate cooling header 51 and the injection pressure of the large flow rate cooling nozzles 53 is gradually decreased from 0.4MPa, the pressure can be adjusted by the flow rate adjustment valve 7 until the injection pressure becomes about 0.04MPa, but if the pressure is made lower than this, the pressure greatly fluctuates due to the difference in the slight opening degree of the flow rate adjustment valve 7, and therefore the pressure cannot be stably adjusted. The flow density of the large-flow cooling nozzle 53 was 1563L/(min. M) at an injection pressure of 0.4MPa 2 ) 494L/(min m) at an injection pressure of 0.04MPa 2 )。
Next, the water flow through the large flow rate cooling header 51 is stopped, and the water flow through the small flow rate cooling header 52 is performed. The flow density of the small-flow cooling nozzle 54 at a jet pressure of 0.4MPa was 417L/(min m) 2 ) It can be seen that the lower limit water amount of the cooling nozzle 53 capable of injecting and flowing at a large flow rate is largeResulting in the same flux density of cooling water. When the injection pressure of the low-flow cooling nozzle 54 is gradually decreased from 0.4MPa, the pressure can be adjusted by the flow rate adjustment valve 7 until the injection pressure becomes about 0.04MPa, but if the pressure is lower than this, the pressure largely fluctuates due to the difference in the subtle opening degree of the flow rate adjustment valve 7, and the pressure cannot be stably adjusted. The flow density of the small-flow cooling nozzle 54 was 132L/(min. M) at an injection pressure of 0.04MPa 2 )。
From the results of fig. 10, it was confirmed that a wide range of spray water amounts can be realized by using cooling nozzles having different flow density.
Next, fig. 11 shows the relationship between the cooling rate and the flow density from 800 ℃ to 400 ℃ at the center in the thickness direction when the steel sheet is actually cooled. Each cooling nozzle has the same configuration as that in the case of fig. 10. Scanning radiation thermometers (not shown) are provided on the input side and the output side of the cooling apparatus, and the surface temperature of the steel sheet is measured in the width direction and the longitudinal direction of the sheet. The average temperature of the steel sheet in the thickness direction was calculated by heat transfer calculation based on the information of the input side and output side thermometers, and the cooling rate in the water cooling process was calculated. The cooling rate was measured at the center of the steel sheet in the width direction and the longitudinal direction.
As shown in fig. 11, the cooling rate can be adjusted in the range of about 20 to 30 ℃/s by cooling with the large flow rate cooling nozzle 53, and the cooling rate can be adjusted in the range of about 7 to 20 ℃/s by cooling with the small flow rate cooling nozzle 54, and it is understood that the cooling rate can be adjusted in a wide range as compared with the case where each cooling nozzle is used alone.
Example 2
As a second example of the present invention, similarly to the first example, the temperature deviation between the cooling rate from 800 ℃ to 400 ℃ at the center in the thickness direction and the temperature in the width direction of the steel sheet after cooling was examined when the steel sheet in the room temperature state (thickness 25mm, sheet width 3500mm, steel sheet length 7 m) was heated to 920 ℃ by the heating furnace 1 and then the pass speed was adjusted so that the steel sheet temperature became 100 ℃ in the cooling apparatus 2 located 2.5m behind the heating furnace 1. The temperature variation in the width direction was measured at a pitch of 20mm in the width direction and at a pitch of 100mm in the longitudinal direction using a scanning radiation thermometer, and the value at the center in the longitudinal direction of the steel sheet was taken as the temperature variation in the width direction.
The cooling device 2 has the same structure as that of fig. 2, and the diameters of the roller table roll 3 and the regulating roll 4 are shown in table 1. The large-flow nozzle 53 and the small-flow nozzle 54 are both flat nozzles, and the injection angle θ, the pitch P' in the width direction, and the twist angle α are shown in table 1. The length of the cooling device 2 was set to 9.0m, and the number of the restricting rollers 4 and the cooling nozzles 53 (54) was as shown in table 1.
[ Table 1]
In examples 1 to 8, the cooling rate can be adjusted in the range of about 20 to 30 ℃/s by cooling with the large flow rate cooling nozzle 53, and the cooling rate can be adjusted in the range of about 7 to 20 ℃/s by cooling with the small flow rate cooling nozzle 54. In this case, the temperature variation in the plate width direction was less than 15 ℃. Then, the strength of the cooling material was measured, and the level was such that there was no particular problem in quality.
In examples 9 to 16, the cooling rate was adjusted in the range of about 20 to 30 ℃/s by cooling with the large flow rate cooling nozzle 53, and the cooling rate was adjusted in the range of about 7 to 20 ℃/s by cooling with the small flow rate cooling nozzle 54. In this case, the temperature variation in the plate width direction is less than 20 ℃. The temperature variation is a level at which the strength of the cooling material is measured after a slight increase in the P/D ratio of 2.0, and there is no particular problem in terms of quality.
Comparative examples 1 to 8 are examples in which the restricting roller pitch P is made larger than in examples 1 to 8. P/D was 3.0, which is outside the scope of the present invention. The cooling rate can be adjusted in the range of about 20 to 30 ℃/s by cooling with the large flow rate cooling nozzle 53, and the cooling rate can be adjusted in the range of about 7 to 20 ℃/s by cooling with the small flow rate cooling nozzle 54. On the other hand, the steel sheet is deformed into a wavy shape under all conditions. It is considered that, when the restricting roller 4 on the input side of the cooling device 2 is visually observed during the cooling operation, a gap is formed between the restricting roller 4 and the steel sheet, and cooling water leaks from the gap to a part in the width direction, thereby locally cooling the steel sheet. Further, the temperature variation in the width direction of the sheet after cooling fluctuates in the range of 27 to 60 ℃, and then the hardness of the steel sheet at the portion where the leaked water adheres is increased when the strength of the cooling material and the like are measured, which causes a problem in quality.
Comparative examples 9 to 16 are examples in which the roll diameter D was reduced as compared with examples 1 to 8 of the present invention. P/D was 2.7, which is outside the scope of the present invention. The cooling rate can be adjusted in the range of about 20 to 30 ℃/s by cooling with the large flow rate cooling nozzle 53, and the cooling rate can be adjusted in the range of about 7 to 20 ℃/s by cooling with the small flow rate cooling nozzle 54. On the other hand, the steel sheet is deformed into a wavy shape under all conditions. It is considered that, when the restricting roller on the cooling device entrance side is visually observed during the cooling operation, a gap is formed between the restricting roller and the steel sheet, and cooling water leaks from the gap to a part in the width direction, thereby cooling the steel sheet. In addition, the temperature variation in the width direction of the steel sheet varies in the range of 35 to 60 ℃, and then the hardness of the steel sheet at the portion where the leaked water adheres is increased when the strength of the cooling material and the like are measured, which causes a problem in terms of quality.
Description of the reference symbols
1. Heating furnace
2. Cooling device
3. Roller way roller
4. Restraining roller
5. Cooling manifold
51. High flow cooling header
52. Small flow cooling header
53. Large-flow cooling nozzle
54. Small flow cooling nozzle
55. Water spray
56. Water spray
57. Medium flow cooling header
58. Medium flow cooling header
59. Medium flow cooling nozzle
60. Medium flow cooling nozzle
6. Flow meter
7. Flow regulating valve
8. Rolling mill
9. Heat straightening machine
S-thick steel plate
P limits the roll spacing
D limiting roll diameter
G roll gap
L spray length
H height of pipe mouth
P' (widthwise) pitch
Theta spray angle
The alpha twist angle.
Claims (8)
1. A cooling device for a thick steel plate, comprising a plurality of restricting rolls arranged in a steel plate conveying direction and a plurality of cooling headers arranged between the restricting rolls,
the ratio P/D of the restricting roller pitch P to the restricting roller diameter D is set to 2.0 to 2.5,
each cooling header is connected to any one of two or more cooling water supply systems,
each cooling water supply system is provided with a regulating valve which can independently control the opening and closing of the water supply and the flow rate,
a plurality of cooling nozzles are installed in each cooling header in the width direction of the steel sheet,
the cooling nozzles adjacent in the width direction of the steel sheet are connected to the cooling headers of different cooling water supply systems, respectively, and,
the flow density of the cooling water sprayed from the cooling nozzles adjacent in the steel sheet width direction is set to be different flow densities, and the cooling water having a flow density three times or more as high as that of the cooling water sprayed from the cooling nozzle spraying the cooling water having the smallest flow density can be sprayed from the cooling nozzle spraying the cooling water having the largest flow density for the same spray pressure,
the cooling device for a thick steel plate is provided with a control means that controls the cooling device using a control valve so as to select each cooling water supply system individually and spray cooling water from a cooling nozzle.
2. The cooling apparatus for thick steel plates according to claim 1,
the distance from the tip of each cooling nozzle to the steel sheet is set to a position within a range of ± 50mm or less with respect to the height of the restraining roll center axis.
3. The cooling apparatus for a thick steel plate according to claim 1 or 2,
each cooling nozzle is at least one of a flat nozzle, a full cone nozzle, a square blowing nozzle and an elliptical blowing nozzle, and the injection angle of the cooling water when the cooling water is injected from each cooling nozzle is in the range of 60 to 120 °.
4. A cooling method for a thick steel plate, using a cooling apparatus in which a plurality of constraining rolls are provided along a steel plate conveying direction and a plurality of cooling headers are arranged between the constraining rolls,
the ratio P/D of the regulating roller pitch P to the regulating roller diameter D is set to be not less than 2.0 and not more than 2.5,
each cooling header is connected to any one of two or more cooling water supply systems,
each cooling water supply system is provided with a regulating valve which can independently perform opening and closing of water supply and flow control,
a plurality of cooling nozzles are installed in each cooling header in the width direction of the steel sheet,
the cooling nozzles adjacent in the width direction of the steel sheet are connected to the cooling headers of different cooling water supply systems, respectively, and,
the flow density of the cooling water sprayed from the cooling nozzles adjacent in the steel sheet width direction is set to be different flow densities, and the cooling water having a flow density three times or more as high as that of the cooling water sprayed from the cooling nozzle spraying the cooling water having the smallest flow density can be sprayed from the cooling nozzle spraying the cooling water having the largest flow density for the same spray pressure,
the control is performed using an adjustment valve so that each cooling water supply system is individually selected and cooling water is injected from the cooling nozzle.
5. The method of cooling a thick steel plate according to claim 4,
the distance from the tip of each cooling nozzle to the steel sheet is set to a position within a range of ± 50mm or less with respect to the height of the restraining roll center axis.
6. The method of cooling a thick steel plate according to claim 4 or 5,
each cooling nozzle is at least one of a flat nozzle, a full cone nozzle, a square spray nozzle and an oval spray nozzle, and the spray angle of the cooling water when the cooling water is sprayed from each cooling nozzle is in the range of 60 to 120 degrees.
7. A thick steel plate manufacturing facility provided with the cooling device according to any one of claims 1 to 3.
8. A method for manufacturing a thick steel plate, comprising a step of cooling by the cooling method according to any one of claims 4 to 6.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017243319 | 2017-12-20 | ||
| JP2017-243319 | 2017-12-20 | ||
| CN201880081519.3A CN111492071A (en) | 2017-12-20 | 2018-12-14 | Cooling device and cooling method for thick steel plate, and thick steel plate manufacturing facility and manufacturing method |
| PCT/JP2018/046067 WO2019124241A1 (en) | 2017-12-20 | 2018-12-14 | Cooling device and cooling method for thick steel sheet, and production equipment and production method for thick steel sheet |
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| CN201880081519.3A Division CN111492071A (en) | 2017-12-20 | 2018-12-14 | Cooling device and cooling method for thick steel plate, and thick steel plate manufacturing facility and manufacturing method |
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| CN115156314A true CN115156314A (en) | 2022-10-11 |
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| CN202210684880.3A Pending CN115156314A (en) | 2017-12-20 | 2018-12-14 | Cooling device and cooling method for thick steel plate, and thick steel plate manufacturing facility and manufacturing method |
| CN201880081519.3A Pending CN111492071A (en) | 2017-12-20 | 2018-12-14 | Cooling device and cooling method for thick steel plate, and thick steel plate manufacturing facility and manufacturing method |
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| Country | Link |
|---|---|
| EP (1) | EP3730633A4 (en) |
| JP (1) | JP6569843B1 (en) |
| KR (1) | KR102430390B1 (en) |
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| KR20220080174A (en) * | 2019-11-25 | 2022-06-14 | 제이에프이 스틸 가부시키가이샤 | Steel plate manufacturing equipment and manufacturing method |
| CN114592112B (en) * | 2022-02-25 | 2023-03-17 | 东北大学 | Flexible cooling device for tempered steel plate |
| CN114635017B (en) * | 2022-05-19 | 2022-09-06 | 北京煜鼎增材制造研究院有限公司 | Spray type heat treatment device and heat treatment method for large metal component |
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| CN103834792B (en) * | 2014-03-26 | 2015-12-30 | 东北大学 | A kind of steel plate continuous roll type quenching process |
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- 2018-12-14 WO PCT/JP2018/046067 patent/WO2019124241A1/en unknown
- 2018-12-14 JP JP2019520653A patent/JP6569843B1/en active Active
- 2018-12-14 KR KR1020207017647A patent/KR102430390B1/en active IP Right Grant
- 2018-12-14 CN CN201880081519.3A patent/CN111492071A/en active Pending
- 2018-12-14 EP EP18891282.8A patent/EP3730633A4/en active Pending
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Also Published As
| Publication number | Publication date |
|---|---|
| CN111492071A (en) | 2020-08-04 |
| JPWO2019124241A1 (en) | 2019-12-19 |
| KR20200085880A (en) | 2020-07-15 |
| JP6569843B1 (en) | 2019-09-04 |
| WO2019124241A1 (en) | 2019-06-27 |
| KR102430390B1 (en) | 2022-08-05 |
| EP3730633A4 (en) | 2020-12-02 |
| EP3730633A1 (en) | 2020-10-28 |
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