US3629015A - Method for cooling thick steel plates - Google Patents

Method for cooling thick steel plates Download PDF

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Publication number
US3629015A
US3629015A US807723A US3629015DA US3629015A US 3629015 A US3629015 A US 3629015A US 807723 A US807723 A US 807723A US 3629015D A US3629015D A US 3629015DA US 3629015 A US3629015 A US 3629015A
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United States
Prior art keywords
cooling
slab
cooling water
temperature
rate
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Expired - Lifetime
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US807723A
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English (en)
Inventor
Toshiya Yonezawa
Hirokazu Sumitomo
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Nippon Steel Corp
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Nippon Steel Corp
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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
    • 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

Definitions

  • the present invention relates to a method for cooling steel materials which are hot after being hot rolled, particularly thick slabs and plates (hereafter called thick steel plates").
  • Thin sheet steel such as a strip can be cooled on the same rolling line merely by water supplied from the showering system, hardly causing deformation.
  • the warped plates lie one upon another in subsequent processes, say, in the heating furnace, which causes such troubles as being caught before being taken into the subsequent rolling mill. Therefore, it is desirable to reduce the production of warped steel plates to the minimum.
  • An object of the present invention which is made as a result of various research efforts to solve troubles arising from cooling of thick steel plates, is to provide a method for water cooling thick steel plates, by which warp production of such plates can be reduced, by controlling the supply of cooling water to the volume appropriate for such cooling, thus eliminating the need for the pressing equipment.
  • Another object of the present invention is to provide a method for water-cooling high-temperature slabs or thick steel plates about 50 mm. thick or more which are hot just after hot rolled, on the hot-rolling line, in a short time by showers cooling of water with almost no such deformations such as warp.
  • the present invention provides for showering cooling water at a rate of 0. I to 0.6 m. per m? of thick steel plate per minute at a pressure of more than 0.8 lag/cm. simultaneously over the top the bottom surfaces of the thick steel plate with a shower hitting area of more than 0.05 m.”/m.
  • FIG. 1 is a side view of an embodiment of the apparatus for use in accordance with the present invention.
  • FIG. 2 is plan figure of the apparatus of FIG. 1.
  • FIG. 3 is detail cross-sectional view of the apparatus of FIG. 1 along the line III-lll.
  • FIG. 4 is cross-sectional view of the cooling water supplying pipe of FIG. 3 along the line IVIV.
  • FIG. 5 is a graphic illustration of the relation between temperature of slab surface and the heat transfer ratel'
  • FIG. 6 is perspective view of the measurement of warp of the thick steel plate.
  • FIG. 7 is a graphic illustration of the relation between thickness of the thick steel plate and shower hitting area thereon.
  • FIGS. 1-4 show one embodiment of a cooling apparatus which may be used in accordance with the present invention, in which a slab 2 which is hot just after being hot rolled, is placed on rollers 1 to be conveyed, and water is sent through a pipe 4 and 9 to cooling water supplying pipes 3 and 10. While the slab is conveyed by the rollers I in the direction of the arrow or while it stops at appropriate intervals, the slab 2 is cooled by water jetted from said cooling water supplying pipes 3 and 10 over both the top and the bottom surfaces. Unless the slab 2 is cooled over both surfaces, it warps so as to become unusable.
  • cooling water sent through the main pipe 6 is branched at an appropriate place to lower cooling water pipes 7 and upper cooling water pipes 8, and is then sent to cooling water forwarding pipes 4 and 9 which extend in the direction of the movement of the slab 2 on the apparatus.
  • An appropriate number of upper cooling water supplying pipes 3 and lower cooling water supplying pipes 10 branched respectively from the cooling water forwarding pipes 4 and 9 are arranged across the slab 2 on the roller table I.
  • Said cooling water supplying pipes 3 and 10 are equipped with a great number of nozzles 3' and 10'. By using such equipment, the high temperature slab 2 is rapidly cooled to the desired temperature.
  • cooling water supplying pipes 3 and 10 with nozzles 3 and 10 provided in such a number as is sufficient to cover the entire surfaces of slab 2.
  • 11 indicates the device for driving the roller table I
  • it is preferred to be able to cool the slabs while they are standing still, but in the case where the space for the cooling line is limited so that the front part or the rear part of the slab 2 is over the end of the cooling zone, it is necessary to cool the slab as it is moved forward or backward; and in the case where a large area is available for the cooling line, cooling can be carried out while the slab 2 is moving forward very slowly.
  • FIG. 4 is cross-sectional view of the cooling water supplying pipe shown in FIG. 3 along the line IV-IV, illustrating the relation between the cooling water supplying pipe 3 and nozzles 3'. As shown in the figure nozzles of one group are arranged zigzag at a certain angle from an adjacent group.
  • FIG. 5 illustrates the relation between surface temperature (0,) s) (C.) of the slab 2 (along the horizontal axis) and heat transfer rate (a) (KcaL/mF, hr. deg.) along the vertical axis, varying according to the change of graduation and volume of cooling water supply (V). It is proved by the graph that in general the higher the surface temperature of the slab (0,), the lower the heat transfer rate (a).
  • heat transfer rate (a) is the function of cooling, that is, the higher the heat transfer rate (a), the greater the cooling effect.
  • the heat transfer rate ((1) falls abruptly. This is because water drops stay on the steam layer produced over the surface of metal when the temperature of said metal is very high, but the drops reach the metal immediately when the temperature is below the critical point, which is generally called Leidenfrost point.” The above phenomenon takes place due to the Leindenfrost point of water drops located around 250 C.
  • the heat transfer rate (11) reaches a peak, that is, it stays lower between 500 and 600 C., and rises when the temperature is between 600 and 700 C.
  • the greater the cooling water supply rate the less the warp production. This does not necessarily mean that the greater the rate, the better, but the rate of about 0.6 mP/mF/min, is best for the purpose, because any greater rate does not influence cooling after saturation. Rather, only the temperature of the cooling water does. In actual operation, the supply of cooling water more than needed results in the necessity of a greater scale of equipment and wasted operation cost and cooling water, thus making the operation uneconomical.
  • the cooling water supply rate it is possible to cool the slab 2 just after hot-rolled to the desired temperature.
  • the shower hitting area (E) which is an area of the surfaces of the slab 2 (expressed in percentage against the whole area) directly hit by cooling water, and pressure of cooling water, should be taken-into consideration.
  • FIG. 7 illustrates the relation between thickness (T) of the slab 2 and the shower hitting area (E) when cooling the slab 2 with showers supplied from the upper cooling water supplying pipes 3 and the lower cooling water supply pipes 10 all of fixed type.
  • the shower hitting area (E) it is determined by the distance from the surface of the slab 2 to the nozzles 3 and 10 and the spreading angle of a jet of cooling water from the nozzles 3' and I0; and when it is so determined, the required number, positions and layout of the nozzles will be determined.
  • the straight line (A) indicates the minimum shower hitting area (E) of the bottom surface of the slab 2, which is determined irrespective of the thickness (T) of the slab 2; if this value is below 530 cm. per m. ofthe slab 2, that is, below 5.3 percent of the slab 2, uneven cooling takes place, causing warp. This process applies also to the top surface of the slab 2.
  • the thickness (T) of the slab 2 on the roller table I changes, and if the nozzles are of fixed type, the distance between the surface of the slab 2 and the nozzles 3 or 10 changes accordingly, such tendency being reflected in the inclination formed by the straight line (B), which means that the slab of greater thickness takes a smaller shower hitting area (E) and vice versa.
  • the principles that the shower hitting area (E) of respective top and bottom surfaces of the slab should be at least 500 cm?, more preferably more than 530 cm. per m of each surface, and that the shower hitting area (E) of the top surface should be the same as or slightly smaller than that of the bottom surface, will not be effective for even cooling.
  • a jet of cooling water from the nozzles 3' and 10 should be provided with a pressure sufficient to break up the steam layer, that is, 0.8 to 0.9 kg./cm. in most cases, more preferably more than I kg./cm. (G). If such considerations as the arrangement of nozzles 3' and 10' and pressure are made, as mentioned above, cooling with showers of cooling water at a rate of 0.l to 0.6 mP/mF/min. will cool the high-temperature slab 2 to room temperature rapidly without warp.
  • the cooling method of the present invention can be applied thereto irrespective of their thickness.
  • final product steel plates even if they are thick or medium thick, may be subjected to a change in quality as cooling tends to harden unless the slabs are as thick as about 50 mm. or more. Therefore, according to the present invention, the cooling is of steel plates of a thickness of about 50 mm. or more.
  • a method for cooling hot-rolled steel plates having a thickness of more than 50 mm. which comprises cooling said plates by showers of cooling water supplied at a rate of 0.1 to 0.6 m. per m of said plates per minute simultaneously over the top and bottom surfaces thereof.
  • a method for cooling hot-rolled steel plates having a thickness of more than 50 mm. which comprises cooling said plates by showers of cooling water supplied at a rate of 0.1 to 0.6 in. per m of said plates per minute at a pressure of more than 0.8 kg./cm. evenly and simultaneously over the top and bottom surfaces thereof with a shower hitting area of 0.05 m. per m

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
US807723A 1968-03-19 1969-03-17 Method for cooling thick steel plates Expired - Lifetime US3629015A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP43017873A JPS4927923B1 (enrdf_load_stackoverflow) 1968-03-19 1968-03-19

Publications (1)

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US3629015A true US3629015A (en) 1971-12-21

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US807723A Expired - Lifetime US3629015A (en) 1968-03-19 1969-03-17 Method for cooling thick steel plates

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US (1) US3629015A (enrdf_load_stackoverflow)
JP (1) JPS4927923B1 (enrdf_load_stackoverflow)
CA (1) CA935309A (enrdf_load_stackoverflow)
DE (1) DE1913835A1 (enrdf_load_stackoverflow)
FR (1) FR2004251A1 (enrdf_load_stackoverflow)
GB (1) GB1261109A (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3829072A (en) * 1972-11-13 1974-08-13 A Fieser Metal slab conditioning system
DE2414445A1 (de) * 1973-03-26 1974-10-10 Usinor Vorrichtung zum khlen von blechen
US3870570A (en) * 1972-11-13 1975-03-11 Arthur H Fieser Method for conditioning metal slabs
US3909315A (en) * 1971-12-29 1975-09-30 Nippon Steel Corp Method for rapid cooling of high temperature metal pieces
US3928090A (en) * 1972-03-09 1975-12-23 British Steel Corp Heat treatment of steel
US3989231A (en) * 1972-03-09 1976-11-02 British Steel Corporation Heat treatment of steel
US4375820A (en) * 1976-10-04 1983-03-08 Hi-Hard Rolls, Inc. Roller for use in a conveyor-roller structure
DE3230866A1 (de) * 1981-08-21 1983-04-07 Nippon Kokan K.K., Tokyo Verfahren und vorrichtung zum kuehlen von stahlblechtafeln
CN105499285A (zh) * 2015-12-31 2016-04-20 柳州钢铁股份有限公司 自动雾化喷淋冷却控温装置

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS498446A (enrdf_load_stackoverflow) * 1972-05-23 1974-01-25
JPS5890313A (ja) * 1981-11-20 1983-05-30 Nippon Steel Corp 鋼板の冷却装置
FR2524001B1 (fr) * 1982-03-25 1987-02-20 Pechiney Aluminium Procede de refroidissement minimisant les deformation s des produits metallurgiques

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3300198A (en) * 1963-12-27 1967-01-24 Olin Mathieson Apparatus for quenching metal
US3364713A (en) * 1963-08-27 1968-01-23 Yawata Iron & Steel Co Method for controlling operations for the cooling of steel plate in accordance with formulae obtained by theoretical analysis
US3423254A (en) * 1964-05-27 1969-01-21 Drever Co Roller pressure quench system
US3479853A (en) * 1967-08-29 1969-11-25 Jones & Laughlin Steel Corp Hot rolling of light gauge strip

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3364713A (en) * 1963-08-27 1968-01-23 Yawata Iron & Steel Co Method for controlling operations for the cooling of steel plate in accordance with formulae obtained by theoretical analysis
US3300198A (en) * 1963-12-27 1967-01-24 Olin Mathieson Apparatus for quenching metal
US3423254A (en) * 1964-05-27 1969-01-21 Drever Co Roller pressure quench system
US3479853A (en) * 1967-08-29 1969-11-25 Jones & Laughlin Steel Corp Hot rolling of light gauge strip

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3909315A (en) * 1971-12-29 1975-09-30 Nippon Steel Corp Method for rapid cooling of high temperature metal pieces
US3928090A (en) * 1972-03-09 1975-12-23 British Steel Corp Heat treatment of steel
US3989231A (en) * 1972-03-09 1976-11-02 British Steel Corporation Heat treatment of steel
US3829072A (en) * 1972-11-13 1974-08-13 A Fieser Metal slab conditioning system
US3870570A (en) * 1972-11-13 1975-03-11 Arthur H Fieser Method for conditioning metal slabs
DE2414445A1 (de) * 1973-03-26 1974-10-10 Usinor Vorrichtung zum khlen von blechen
US4375820A (en) * 1976-10-04 1983-03-08 Hi-Hard Rolls, Inc. Roller for use in a conveyor-roller structure
DE3230866A1 (de) * 1981-08-21 1983-04-07 Nippon Kokan K.K., Tokyo Verfahren und vorrichtung zum kuehlen von stahlblechtafeln
CN105499285A (zh) * 2015-12-31 2016-04-20 柳州钢铁股份有限公司 自动雾化喷淋冷却控温装置

Also Published As

Publication number Publication date
CA935309A (en) 1973-10-16
FR2004251A1 (enrdf_load_stackoverflow) 1969-11-21
JPS4927923B1 (enrdf_load_stackoverflow) 1974-07-22
DE1913835A1 (de) 1969-10-16
GB1261109A (en) 1972-01-19

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