Classifications

• • 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
  • B21B45/04—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 de-scaling, e.g. by brushing
  • B21B45/08—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 de-scaling, e.g. by brushing hydraulically
• • 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
  • B21B45/04—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 de-scaling, e.g. by brushing
  • B21B45/06—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 de-scaling, e.g. by brushing of strip material
• • 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
  • B21B2273/00—Path parameters
  • B21B2273/12—End of product
  • B21B2273/14—Front end or leading end
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B2273/00—Path parameters
  • B21B2273/12—End of product
  • B21B2273/16—Tail or rear end
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B2273/00—Path parameters
  • B21B2273/18—Presence of product
• • 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
  • B21B37/28—Control of flatness or profile during rolling of strip, sheets or plates
  • B21B37/44—Control of flatness or profile during rolling of strip, sheets or plates using heating, lubricating or water-spray cooling of the product
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B38/00—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product
• • 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

Definitions

• the present invention relates to a method for cooling a steel sheet, and more particularly to a method for cooling a hot-rolled steel sheet.
• a process is widely used in which a steel sheet after hot rolling is continuously cooled by a cooling device and the structure of the steel sheet is controlled to produce a high-strength, high-tough steel plate. This manufacturing process contributes to the reduction of manufacturing costs by reducing alloy elements and the improvement of welding work efficiency.
• the temperature at the front end and the rear end of the steel plate is lower than that at the central portion in the longitudinal direction of the steel plate before being transferred to the cooling device. Even in cooling, the effect of heat transfer and heat conduction from the end face is large, so an overcooling phenomenon occurs and the flatness and material tend to become unstable.
• the masking method disclosed in JP-A-60-43435 described above has a great effect of preventing overcooling the front and rear ends of the steel plate.
• this is ON / OFF control, that is, the masking part is masked with no water injection. Since the cooling water of the reference water density is supplied to the non-masking part (also referred to as the non-masking part), the water quantity changes abruptly at this boundary, and a large temperature deviation occurs especially at the tip of the steel plate.
• the present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved steel sheet cooling method capable of enhancing uniform cooling in the steel sheet conveyance direction. There is.
• the present invention has been made to solve the above-mentioned problems, and the gist is as follows.
• the water is injected so that the cooling water volume becomes the reference water volume density, and while the central area is passing, the water injection is continued at the reference water volume density, and the steel plate is installed at the rear stage of the cooling device. While the tip area of 80% to 95% by volume of the volume density, and when the tip area passes, the amount of cooling water is increased sequentially from 80% to 95% by mass of the reference water volume density to reach the boundary between the tip area and the center area.
• the steel sheet cooling method is characterized in that water is injected so that the cooling water amount becomes the reference water amount density and the water injection is continued at the reference water amount density while the central region is passing.
• the tail end side from the central region of the steel sheet is divided into a rear region and a rear end region with respect to the conveying direction of the steel plate, and the central region of the steel plate passes through the front and rear stages of the cooling device.
• the cooling water amount is sequentially decreased from the reference water amount density, and when the boundary between the rear region and the rear end region is reached, the cooling water amount is 80 to 95 vol% of the reference water amount density.
• FIG. 1 is a schematic diagram showing a cooling device according to the first embodiment of the present invention.
• FIG. 2 is an explanatory diagram showing a water density distribution in the longitudinal direction of the steel sheet in the upstream region 4a of the cooling device according to the embodiment.
• FIG. 3 is an explanatory diagram showing the water density distribution in the longitudinal direction of the steel sheet in the rear region 4 b of the cooling device according to the embodiment.
• FIG. 4 is an explanatory diagram showing a surface temperature distribution of the steel plate in the longitudinal direction of the steel plate according to the embodiment.
• FIG. 5 shows the surface temperature component of the steel sheet on the outlet side of the cooling device according to the embodiment. It is explanatory drawing which shows cloth.
• Fig. 6 is an explanatory diagram showing the surface temperature distribution of the steel sheet on the exit side of a conventional cooling device.
• the cooling device In the method of forcibly cooling the thick steel plate after hot rolling with cooling water, the cooling device is divided into the front and rear zones, and the cooling water is turned on and off by the three-way valve to mask the leading and trailing edges of the thick steel plate. In doing so, since the temperature drop at the boundary between the masked part and the non-masking part is large at the front part of the thick steel plate (about 1.5 times that at the rear part), the method for controlling this temperature drop The inventor conducted various experiments and studies.
• the temperature drop region at the boundary is as short as 2 to 3 m, and the valve opening time of the flow control valve (time from fully closed to fully opened) is about 10 s at the earliest, The transfer speed (1.0 to 2.0 m Z s) cannot be reduced.
• the reference water density (the quantity of water that is the quantity of water per unit area supplied to the central part of the steel sheet per unit time (unit: m 3 (m 2 -min)) 80 to 95 vol% of Q o (Hereinafter, this water density is referred to as Q. nl .)
• Q. nl the reference water density
• the reference water density Q o is preferably in the range of 0.3 to 1.5 m (m 2 -rain) in the case of a thick steel plate, for example.
• a water density of 1.5 m 3 (m 2 -min) or more the temperature at the end of cooling is often low, and the surface of the thick steel plate being cooled The temperature is also lowered.
• the main component is cooling in the nucleate boiling region where the cooling is stable, so the temperature deviation after cooling is less likely to increase, and adverse effects due to temperature deviation occur. It is difficult, and the frequency applied in the present invention is low.
• the reference water volume density Q o is, for example, 0.3 m 3 / (m 2 min) or less
• the cooling rate is low, so that the structure of the steel plate can be prevented from becoming coarse. Since the strength of the steel sheet cannot be improved, a water density of ⁇ . ⁇ 3 / (m 2 -min) or less is used less frequently and the applicability of the present invention is low.
• the reference water density Q o is mainly determined by the material of the steel sheet to be cooled, and in addition, the temperature of the steel sheet before cooling with the cooling device and the target temperature of the steel sheet after cooling. It is determined by various factors such as the difference, the thermal conductivity of the steel sheet, and the cooling type of the cooling nozzle.
• the temperature of the steel plate before cooling ranges from the heating furnace to the cooling device through the rolling mill. It varies depending on factors such as the duration of time and rolling method.
• FIG. 1 is a schematic diagram showing a cooling device for carrying out the cooling method according to the first embodiment of the present invention.
• FIG. 2 is an explanatory diagram showing the water density distribution in the longitudinal direction of the steel sheet in the upstream region of the cooling device according to the present embodiment.
• FIG. 3 is an explanatory diagram showing the water density distribution in the longitudinal direction of the steel sheet in the subsequent region of the cooling device according to the present embodiment.
• FIG. 4 is an explanatory diagram showing the surface temperature distribution of the steel sheet in the longitudinal direction of the steel sheet according to this embodiment.
• FIG. 5 is an explanatory diagram showing the surface temperature distribution of the steel sheet on the outlet side of the cooling device according to the present embodiment.
• a steel plate rolling mill 1 is installed adjacent to the cooling device 4 according to the present embodiment.
• the cooling device 4 includes a length measuring roll 2, a steel plate position detection sensor 3, a cooling nozzle 4 c, a three-way valve 5, a flow rate adjusting valve 6, a header pipe 7, and a control unit 8.
• the cooling device 4 is divided into a front region 4a and a rear region 4b.
• a plurality of cooling nozzles 4 c are provided in the length direction and the width direction with respect to the steel plate P in order to sprinkle the cooling water on the upper surface and the lower surface of the steel plate P to be cooled.
• Each cooling nozzle 4c is provided at the tip of a pipe branched from the header pipe 7.
• a three-way valve 5 and a flow control valve 6 are provided in the former area 4a, and the latter area 4 In b, a flow control valve 6 is provided.
• the control unit 8 tracks the position of the steel plate P based on the detection information of the length measuring roll 2 and the steel plate position detection sensor 3, and adjusts and controls the opening degree of the three-way valve 5 and the flow control valve 6 based on this tracking information. To do.
• the steel plate P to be cooled has a tip region (for example, a region from 0.5 to 2 m from the tip of the steel plate toward the center in the longitudinal direction of the steel plate) 1, and a tip region (tip region and tip part). From the boundary with the region toward the center of the steel plate in the longitudinal direction, for example, a region from 4 to 10 m) 1 2 and the center region (the tip region) The amount of cooling water supplied from the cooling device 4 is adjusted and controlled, for convenience, in three regions: the central region on the steel plate longitudinal direction side of the boundary between the central region and the central region.
• the range of these three regions is determined by the cooling conditions such as the relationship between the response speed of the flow control valve 6 and the steel sheet transport speed, the water density, and the steel sheet temperature at the end of cooling. It is also determined by the temperature distribution of the steel sheet before cooling.
• the temperature distribution of the steel plate before cooling varies depending on various factors such as the time from the heating furnace to the cooling device through the rolling mill, the rolling method, the heat transfer coefficient of the steel plate, and the material.
• the flow rate control valve 6 and the Mikata valve 5 in the control unit 8 will be described.
• the water density is Q in the front region 4a and the rear region 4b of the cooling device 4. Allow the water flow through the flow control valve 6 with the degree of opening reduced to nl .
• the flow control valve 6 and the three-way valve 5 are controlled so that the one-way valve 5 in the front region 4a is opened to the off-line side (the side off the pass line of the steel plate P). This makes the water density Q fr .
• the nl of cooling water is drained to the offline side in the front area 4a, and the water is sprinkled from the cooling nozzle 4c in the rear area 4b.
• the tip of the steel plate P enters the cooling device 4, and the steel plate P sequentially passes between the upper and lower cooling nozzles 4c.
• the cooling device 4 In the front stage region 4a, the tip region 1 of the steel plate P passes through the cooling nozzle 4c position (the position where each cooling nozzle 4c is provided) in all the cooling nozzles 4c, and the front part of the steel plate P
• the three-way valve 5 is sequentially switched to the on-line side, and water spraying is sequentially started on the steel sheet P from each cooling nozzle 4c provided in the longitudinal direction of the steel sheet. .
• FIG. 6 is an explanatory diagram showing the surface temperature distribution of the steel sheet on the exit side of the conventional cooling device.
• the steel plate P to be cooled includes a rear end region (region from the rear end of the steel plate toward the center in the longitudinal direction of the steel plate), a rear region (region from the rear end region toward the center of the steel plate in the longitudinal direction), a center region,
• the amount of cooling water supplied from the cooling device 4 is adjusted and controlled.
• the range of these three regions is determined by, for example, the relationship between the response speed of the flow control valve 6 and the conveying speed of the steel sheet, the cooling conditions such as the water density and the temperature of the steel sheet at the end of cooling. It is also determined by the temperature distribution of the steel sheet before cooling.
• the temperature distribution of the steel plate before cooling varies depending on various factors such as the time from the heating furnace to the cooling device through the rolling machine, the rolling method, the heat transfer coefficient of the steel plate, and the material.
• the central region of the thick steel plate P is in the front region 4 a of the cooling device 4. While the water is passing, water is cooled with the reference water density Q o, but when the rear region of the steel plate P reaches the cooling nozzle 4 c position, the opening of the flow control valve 6 provided in the cooling nozzle 4 c is increased in order.
• the water density is the above Q I r until the rear end region is reached after the next squeezing. to be nt .
• the three-way valve 5 is switched to the off-line side, the cooling water is discharged to the off-line side, and the sprinkling of the cooling water to the rear end area is stopped.
• This operation is sequentially performed according to the movement of the cooling nozzle 4 c from the inlet side to the outlet side of the cooling device 4 to the rear part of the thick steel plate P.
• the water spray is cooled at the reference water density Q o as described above, but the thick steel plate is located below the cooling nozzle 4 c.
• the flow control valve 6 provided in the cooling nozzle 4 c opens. The water density is above Q ⁇ when the rear end region is reached by narrowing down the degree sequentially. to be nt . Then, the rear end area is sprinkled and cooled while maintaining the opening degree.
• Table 1 is a table showing the thickness distribution of each of the thick steel plates 1 to 3, the plate width, the plate length, and the temperature distribution before passing through the cooling device.
• Table 2 shows the water density of Examples 1 to 3 and Comparative Examples 1 and 2 when the steel plates 1 to 3 shown in Table 1 are cooled while being conveyed at a speed of 60 mZ min. It is a table
• the cooling nozzle 4 c is a cooling device in which 24 rows are arranged in the steel plate conveyance direction (steel plate length direction), and 70 nozzles are arranged in a direction perpendicular to the steel plate conveyance direction (steel plate width direction).
• the front area 4a is set to the 12th row of the cooling nozzle 4c, and the rear area 4b is set to the 24th row thereafter.
• the three-way valve, flow control valve, control unit, etc. have the same configuration as in Fig. 1.
• the tip region 1 of the steel sheet is 1 m, above region 1 2 from steel tip, tip region 1, and 4 m from the boundary portion between the front portion region 1 2, the central region from the previous region 1 2 After the boundary with the central region.
• Example 1 in Table 2 is an example in which the present invention is not applied to the rear region and the rear end region of the thick steel plate 1, and cooling is performed at the reference water density.
• Examples 2 and 3 are the front region and the front end. This is an example in which the present invention is applied to a region, a rear region, and a rear end region.
• the water density Q fr in the preceding zone when the tip region passes through the cooling device. nt is 90% by volume in Example 1, 82% by volume in Example 2, and 95% by volume in Example 3 with respect to the reference water density Q o, when the rear region finishes passing through the cooling device.
• the water density in the latter zone is 82% by volume in Example 2 with respect to the standard water density Q o.
• it is 95 volume%, and is in the range of 80-95 volume%
• Examples 1-3 are examples to which the present invention is applied.
• Comparative Example 1 is an example (97% by volume) when the water density of the cooling water in the front part of the steel sheet, the front part of the cooling device in the rear part, and the cooling water volume density in the rear part is outside the upper limit of the present invention.
• Comparative Example 2 is an example (75% by volume) when the water density of the present invention is outside the lower limit. In either case, the maximum temperature deviation of the steel plate after cooling is significantly larger than in Examples 1 to 3 (27 ° C in Comparative Example 1 and 29 in Comparative Example 2), and the steel plate shape after cooling is also It got worse.
• the present invention it is possible to suppress a significant temperature drop at the boundary between the tip region of the thick steel plate masked in the longitudinal direction of the steel plate and the tip region of the non-masking portion, It becomes possible to improve the shape of the tip region and to suppress the material change in the longitudinal direction of the steel sheet. Further, the steel plate shape and material can be further improved at the rear part of the thick steel plate, which is preferable. In summary, according to the present invention, it is possible to improve the uniform cooling property in the steel plate conveyance direction, to make the material uniform and to improve the flatness of the steel plate.
• Thick steel plate 1 Thick steel plate 2 Thickness ftq pole 3 Thickness [mm] 20 20 20 Strip width [mm] 3032 2988 3010 Plate length [mm] 29542 30462 29872 Maximum [by] 808 809 810 Tip area

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (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)

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• 2006
  • 2006-08-18 JP JP2006223636A patent/JP4119928B2/ja active Active
• 2007
  • 2007-07-31 EP EP07791993A patent/EP1925373B1/en active Active
  • 2007-07-31 RU RU2008131698/02A patent/RU2386505C1/ru active
  • 2007-07-31 KR KR1020087016005A patent/KR100882931B1/ko active Active
  • 2007-07-31 CN CN200780004189XA patent/CN101378856B/zh active Active
  • 2007-07-31 US US12/223,367 patent/US8282747B2/en active Active
  • 2007-07-31 WO PCT/JP2007/065320 patent/WO2008020549A1/ja active Application Filing
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  • 2007-07-31 DE DE602007005581T patent/DE602007005581D1/de active Active
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