EP0145485B1 - Method of controlling the temperature of steel strip in the cooling zone of a continuous annealing furnace - Google Patents

Method of controlling the temperature of steel strip in the cooling zone of a continuous annealing furnace Download PDF

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Publication number
EP0145485B1
EP0145485B1 EP84308613A EP84308613A EP0145485B1 EP 0145485 B1 EP0145485 B1 EP 0145485B1 EP 84308613 A EP84308613 A EP 84308613A EP 84308613 A EP84308613 A EP 84308613A EP 0145485 B1 EP0145485 B1 EP 0145485B1
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EP
European Patent Office
Prior art keywords
cooling
strip
temperature
rolls
gas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP84308613A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0145485A2 (en
EP0145485A3 (en
Inventor
Kuniaki C/O Hiroshima T.I. Mitsubishi J. Tanouchi
Yasunobu C/O Hiroshima T.I. Mitsubishi J. Hayama
Takeo Fukushima
Sachihiro C/O Mizushima W Kawasaki Steel Corp Iida
Norihisa C/O Mizushima W.Kawasaki St.C. Shiraishi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Steel Corp
Mitsubishi Heavy Industries Ltd
Original Assignee
Mitsubishi Heavy Industries Ltd
Kawasaki Steel Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Heavy Industries Ltd, Kawasaki Steel Corp filed Critical Mitsubishi Heavy Industries Ltd
Publication of EP0145485A2 publication Critical patent/EP0145485A2/en
Publication of EP0145485A3 publication Critical patent/EP0145485A3/en
Application granted granted Critical
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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
    • 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

Definitions

  • This invention relates to a method of controlling the temperature of steel strip in the cooling zone of a continuous annealing furnace.
  • a continuous annealing furnace is an apparatus which performs the heat treatment of the cold rolled steel strip in accordance with a heat cycle as shown by way of example in Figure 1 in order to improve its workability.
  • the heat treatment according to the heat cycle of Figure 1 is effected by a furnace having a fast cooling zone and a final cooling zone.
  • FIG. 2 shows the cooling system disclosed in Japanese Patent Publication No. 10973/1981.
  • a steel strip 1 travels in contact with four cooling rolls 2 to 5 in which a coolant flows, and its heat is transferred to the cooling rolls.
  • Four plenum chambers 6 to 9 are provided in front of the cooling rolls 2 to. 5, respectively, for blowing jets of cooling gas against the strip 1.
  • Each plenum chamber has a plurality of nozzles through which the cooling gas is jetted out of the plenum chamber.
  • FIG. 2 also shows a pair of deflector rolls 10 and 11, devices 22 for moving the cooling rolls to control the angle at which the strip is brought into contact with the cooling rolls, pressure controllers 23 for controlling the pressure of the cooling gas in the plenum chambers, sensors 24 for detecting the pressure of the cooling gas in the plenum chambers and dampers 25.
  • the coolant is circulated through the cooling rolls 2 to 5 by a circuit which is shown by way of example in Figure 3 as disclosed in Japanese Patent Application No. 129069/1982.
  • Figure 3 shows only one of the cooling rolls at 2 for the sake of simplicity.
  • the coolant is returned from the cooling roll 2 to a coolant tank 15 through a discharge line 14. It is delivered by a pump 16 from the tank 15 to a heat exchanger 17 in which it is cooled, and supplied to the cooling roll 2 by a supply line 18.
  • the temperature of the coolant entering the cooling roll is controlled by a coolant temperature controller 19. More specifically, the coolant temperature is detected by a sensor 20 and the flow of cooling water entering the heat exchanger 17 is controlled by a control valve 21 to obtain an appropriate coolant temperature set by the temperature controller 19.
  • the cooling system employing the combination of roll cooling and gas jet cooling as hereinabove described effects the control of the temperature of the strip 1 by controlling three variable factors, i.e., the length of a strip portion contacting each cooling roll or in other words the angle at which the strip is brought into contact with each cooling roll, the coolant temperature and the flow rate of the cooling gas blown against the strip.
  • the control of the coolant temperature has already been described.
  • the angle at which the strip contacts the cooling rolls is controlled by the roll moving devices 22.
  • the flow rate of the cooling gas is controlled by adjusting the position of each damper 25 so that the pressure of the cooling gas detected by the pressure sensors 24 may reach a predetermined level.
  • a predetermined strip temperature is obtained in the cooling zone by controlling the flow rate of the cooling gas, the angle at which the strip is brought into contact with the cooling rolls and the coolant temperature in the order mentioned in claim 1.
  • the control of the strip temperature is effected by varying the three control factors or parameters in a specific order of preference.
  • This order of preference is determined by the quickness in the response of control.
  • the quickness in the response of control has the most important bearing on an improved yield of production in the event there is any change in the conditions of the annealing operation, for example, during the passage of a welded joint between two strips which are different in gauge.
  • the three control factors or parameters differ from one another in response time, as follows:
  • priority is in the order of (1) flow rate of cooling gas, (2) angle of the strip relative to the cooling rolls and (3) coolant temperature. This is exactly the order of quickness in response and enables a high yield of production irrespective of any changes in the annealing conditions.
  • the flow rate of cooling gas and the angle of the strip relative to the cooling rolls are first controlled simultaneously, and the control of the coolant temperature having a longer response time is delayed. This delay ensures an improved yield of production.
  • the simultaneous control of the flow rate of the cooling gas and the angle of the strip has the advantage of achieving a large change in the cooling conditions at a time within a relatively short length of time.
  • Figure 4 is a graphical illustration of the control of the three factors for the continuous cooling of a plurality of strips which gradually increase in gauge, while the other annealing conditions remain the same for all the strips.
  • the points marked o in Figure 4 are the starting points.
  • the flow rate of cooling gas has reached its maximum level, the angle of the strip relative to the cooling rolls is, then, increased with an increase in strip gauge as shown at B in Figure 4, as long as there is any room for such increase in the angle.
  • the coolant temperature is lowered, as shown at C in Figure 4, in order to increase the cooling capacity to the cooling system, though it shows a slower response to control than the other two factors.
  • Figure 5 is a graphical illustration of the control of the three factors for the continuous cooling of a plurality of strips which gradually decrease in gauge. With a gradual reduction in strip gauge, the flow rate of cooling gas is first decreased as shown at A' in Figure 5, then the angle of the strip relative to the cooling rolls is decreased as shown at B', and finally the coolant temperature is raised as shown at C'.
  • Figure 6 is a graphical illustration of the control of the three factors for the continuous cooling of a plurality of strips having first a gradually increasing gauge and then a gradually decreasing gauge. The control underthis situation may be effected by a combination of the procedures shown in Figures 4 and 5. It will, however, be noted that Figure 6 shows an example of operation in which the coolant temperature is not varied irrespective of the change in strip gauge.
  • Figure 7 is a flow chart showing by way of example the calculations which are performed for setting the three factors at optimum levels for the cooling of each strip.
  • the following symbols have the following meanings:
  • the cooling curve for strip can be obtained by the integration of equation (1) by the length of the strip portion cooled by the cooling rolls and the cooling gas.
  • the relationship between the coefficient a of heat transfer to the cooling gas and the flow rate of the cooling gas (in the case of cooling by the system of Figure 2, the pressure P of the cooling gas in the plenum chambers) may be determined experimentally as expressed, for example, by the following equation: where P: pressure of the cooling gas in the plenum chambers;
  • the pressure P of the cooling gas in the plenum chambers which makes it possible to obtain the target value of the final strip temperature may be determined in accordance with equations (1) and (2) by taking into account the specific values of the angle of the strip relative to the cooling rolls and the coolant temperature T W which are known.
  • the angle which makes it possible to obtain the target value of the final strip temperature may be determined in accordance with equations (1) and (2) by taking into account the specific values of the flow rate of the cooling gas or the pressure P of the cooling gas in the plenum chambers and the coolant temperature T w which are known.
  • the angle may be expressed by the following equation: °(iv) Calculation of the Coolant Temperature:
  • the coolant temperature T w which makes it possible to obtain the target value of the final strip temperature may be determined in accordance with equations (1) and (2) by taking into account the flow rate of the cooling gas or the pressure P of the cooling gas in the plenum chambers and the angle of the strip relative to the cooling rools which are known.
  • this invention is most saliently characterized by effecting the perferential control of one or two factors or parameters having a better response to control than the other factor or factors, while keeping the other factor or factors intact as far as practically feasible.
  • the method of this invention makes it possible to achieve the best possible yield of production irrespective of any change in the annealing conditions.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Control Of Heat Treatment Processes (AREA)
EP84308613A 1983-12-15 1984-12-11 Method of controlling the temperature of steel strip in the cooling zone of a continuous annealing furnace Expired - Lifetime EP0145485B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP58234986A JPS60128220A (ja) 1983-12-15 1983-12-15 連続焼鈍炉冷却帯のストリツプ温度制御方法
JP234986/83 1983-12-15

Publications (3)

Publication Number Publication Date
EP0145485A2 EP0145485A2 (en) 1985-06-19
EP0145485A3 EP0145485A3 (en) 1986-12-10
EP0145485B1 true EP0145485B1 (en) 1990-03-07

Family

ID=16979354

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84308613A Expired - Lifetime EP0145485B1 (en) 1983-12-15 1984-12-11 Method of controlling the temperature of steel strip in the cooling zone of a continuous annealing furnace

Country Status (7)

Country Link
EP (1) EP0145485B1 (ja)
JP (1) JPS60128220A (ja)
KR (1) KR890002799B1 (ja)
CA (1) CA1239570A (ja)
DE (1) DE3481528D1 (ja)
ES (1) ES8602459A1 (ja)
ZA (1) ZA849681B (ja)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62149820A (ja) * 1985-12-24 1987-07-03 Kawasaki Steel Corp 鋼帯の冷却方法
US5182074A (en) * 1990-07-31 1993-01-26 Nkk Corporation Apparatus for continuously cooling metal strip
DE69324566T2 (de) * 1992-06-23 1999-10-28 Nippon Kokan Kk Kühlungsvorrichtung und -verfahren für metallband
JP2022183534A (ja) * 2021-05-31 2022-12-13 トヨタ自動車株式会社 離型剤噴霧装置および離型剤噴霧方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5610973B2 (ja) * 1973-12-13 1981-03-11
JPS54118315A (en) * 1978-03-08 1979-09-13 Nippon Kokan Kk <Nkk> Metal belt cooling
AU530384B2 (en) * 1979-06-28 1983-07-14 Nippon Kokan Kabushiki Kaisha Controlled cooling of steel strip to effect continuous annealing
JPS5726127A (en) * 1980-07-25 1982-02-12 Nippon Steel Corp Cooler for continuous annealing line for high tensile steel
FR2499591A1 (fr) * 1981-02-12 1982-08-13 Stein Heurtey Dispositif de refroidissement rapide et controle dans un four de recuit en atmosphere neutre ou reductrice

Also Published As

Publication number Publication date
ES539293A0 (es) 1985-11-16
KR850004995A (ko) 1985-08-19
ES8602459A1 (es) 1985-11-16
DE3481528D1 (de) 1990-04-12
KR890002799B1 (ko) 1989-07-31
EP0145485A2 (en) 1985-06-19
EP0145485A3 (en) 1986-12-10
CA1239570A (en) 1988-07-26
JPS639569B2 (ja) 1988-02-29
JPS60128220A (ja) 1985-07-09
ZA849681B (en) 1986-04-30

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