EP0495115A1 - System for continuously cooling metal strip - Google Patents
System for continuously cooling metal strip Download PDFInfo
- Publication number
- EP0495115A1 EP0495115A1 EP91913119A EP91913119A EP0495115A1 EP 0495115 A1 EP0495115 A1 EP 0495115A1 EP 91913119 A EP91913119 A EP 91913119A EP 91913119 A EP91913119 A EP 91913119A EP 0495115 A1 EP0495115 A1 EP 0495115A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- cooling
- steel strip
- metal strip
- width direction
- 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.)
- Granted
Links
- 238000001816 cooling Methods 0.000 title claims abstract description 368
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 108
- 239000002184 metal Substances 0.000 title claims abstract description 108
- 239000007789 gas Substances 0.000 claims abstract description 129
- 239000000112 cooling gas Substances 0.000 claims abstract description 63
- 238000009826 distribution Methods 0.000 claims abstract description 62
- 238000007664 blowing Methods 0.000 claims abstract description 38
- 239000000110 cooling liquid Substances 0.000 claims abstract description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 11
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Images
Classifications
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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
-
- 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
Definitions
- the present invention relates to an apparatus for continuously cooling a metal strip, which is continuously travelling in the longitudinal direction thereof, so as to achieve a uniform temperature distribution in the width direction of the metal strip.
- continuous annealing of a metal strip is carried out as follows: A metal strip continuously travelling in the longitudinal direction thereof is continuously heated to a prescribed temperature and soaked. Then, the metal strip thus heated and soaked, which is continuously travelling in the longitudinal direction threreof, is continuously cooled to a prescribed temperature at a prescribed cooling rate immediately or after slowly cooling to a prescribed temperature. Then, the metal strip thus cooled is continuously subjected to an overaging treatment or a tempering treatment.
- the known methods include a water cooling, a gas cooling and a roll cooling.
- the roll cooling has an advantage of permitting rapid cooling of the metal strip to any temperature. In this respect, the roll cooling is superior to the water cooling and the gas cooling.
- Japanese Patent Publication No. 57-14,414 dated March 24, 1982 discloses an apparatus for continuously cooling a metal strip, which comprises: a plurality of cooling rolls, which are freely rotatable and in contact with a metal strip continuously travelling in the longitudinal direction thereof, for continuously cooling said metal strip, each of said plurality of cooling rolls having a length at least equal to the width of said metal strip, said plurality of cooling rolls having respective axes in parallel with each other, a cooling liquid flowing through the interior of each of said plurality of cooling rolls to continuously cool same, and at least one of said plurality of cooling rolls is displaceable toward said metal strip to control a contact area between the surface of said cooling roll and the surface of said metal strip (hereinafter referred to as the "prior art 1").
- Fig. 35 is a descriptive view illustrating a typical apparatus for continuously cooling a metal strip, for example, a steel strip according to the above-mentioned prior art 1.
- a plurality of cooling rolls 2 comprising, for example, five rolls 2a to 2e, which are freely rotatable and in contact with a steel strip 1 continuously travelling in the longitudinal direction thereof, for continuously cooling the steel strip, are arranged with the axes thereof in parallel with each other, at prescribed intervals.
- Each of the cooling rolls 2 has a length at least equal to the width of the steel strip 1, and a cooling liquid flows through the interior of the cooling roll 2 to continuously cool same.
- Each of the cooling rolls 2 is displaceable toward the steel strip 1 by a driving mechanism not shown, to control the contact area between the surface of the cooling roll 2 and the surface of the steel strip 1.
- the steel strip 1 continuously travels in the direction as shown by the arrow in Fig. 35, while coming into contact with each of the above-mentioned plurality of cooling rolls 2. In the meantime, the portion of the surface of the steel strip 1 in contact with the surface of each of the cooling rolls 2 is cooled.
- the contact area between the surface of the steel strip 1 and the surface of each of the cooling rolls 2 is controlled by causing each of the cooling rolls 2 to displace toward the steel strip 1.
- the steel strip 1 is thus continuously cooled to a prescribed temperature by the plurality of cooling rolls 2.
- the above-mentioned prior art 1 has the following problems: In order to continuously cool the steel strip 1 continuously travelling in the longitudinal direction thereof so as to achieve a uniform temperature distribution in the width direction thereof, it is necessary to bring the surface of the steel strip 1 and the surface of each of the plurality of cooling rolls 2 into close contact with each other uniformly in the width direction of the steel strip 1.
- Fig. 36 is a graph illustrating a temperature distribution of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 under, for example, the following conditions by means of the cooling apparatus according to the prior art 1 as shown in Fig. 35:
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof, and the ordinate represents a temperature of the steel strip 1 in the width direction thereof.
- the temperature of the steel strip 1 in the width direction thereof on the exit side of the cooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 100 mm from the side edge of the steel strip 1, and is about 570°C at a position, for example, of 20 mm from the side edge of the steel strip 1, and about 350°C at a position of 100 mm from the side edge thereof.
- the temperature distribution in the width direction of the steel strip 1 on the exit side of the cooling roll 2e is non-uniform with a higher temperature on the side edge than at the center, the difference in temperature being approximately 220°C between the center and the side edge. This causes occurrence of a defective shape such as edge waves or heat buckles in the steel strip 1 after the roll cooling.
- Fig. 37 is a graph illustrating an aging index (AI) of the above-mentioned steel strip 1 in the width direction thereof, when the steel strip 1 is subjected to an overaging treatment at a temperature of 350°C for two minutes, then to a temper rolling with a reduction ratio of 1.5%, and then, to an aging treatment at a temperature of 100°C for 60 minutes.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof
- the ordinate represents an aging index (AI) of the steel strip 1 in the width direction thereof.
- the higher yield point of the steel strip 1 resulting from the aging causes occurrence of a defective shape and a spring-back during the press-forming and deterioration of a yield point elongation and a buckling resistance of the steel strip 1.
- the extent of the occurrence of these defects differs in the width direction of the steel strip 1.
- the upper limit of the aging index (AI) up to which a yield point elongation does not occur during the press-forming is assumed to be, for example, 4 kgf/mm2, then, as is clear from Fig. 37, the portion from the side edge to about 90 mm of the steel strip 1 would have a high aging index of over 4 kgf/mm2. This leads to non-uniform mechanical properties of the steel strip 1 in the width direction thereof.
- Japanese Patent Provisional Publication No. 2-274,822 dated November 9, 1990 discloses an apparatus for continuously cooling a steel strip, which comprises: a plurality of cooling rolls, which are freely rotatable and in contact with a steel strip continuously travelling in the longitudinal direction thereof, for continuously cooling said steel strip, each of said plurality of cooling rolls having a length at least equal to the width of said steel strip, said plurality of cooling rolls having respective axes in parallel with each other, a cooling liquid flowing through the interior of each of said cooling rolls to continuously cool same; and a gas cooler, arranged on the exit side of said plurality of cooling rolls, for continuously cooling said steel strip by blowing a cooling gas onto the surface of said steel strip so as to achieve a uniform temperature distribution in the width direction of said steel strip after the final cooling thereof, said gas cooler being arranged in the width direction of said steel strip at a prescribed distance from each of the both surfaces of said steel strip, said gas cooler comprising
- Fig. 38 is a descriptive view illustrating a typical apparatus for continuously cooling a steel strip according to the above-mentioned prior art 2.
- a plurality of cooling rolls 2 of the same construction as those described in the prior art 1 for continuously cooling a steel strip 1 continuously travelling in the longitudinal direction thereof.
- a gas cooler 3 is arranged on the exit side of the plurality of cooling rolls in the width direction of the steel strip 1 continuously travelling in the longitudinal direction thereof, at a prescribed distance from each of the both surfaces of the steel strip 1.
- Fig. 39 is a schematic perspective view illustrating
- the gas cooler 3 comprises a plurality of mutually independent nozzle headers 4 for blowing a cooling gas onto the surface of the steel strip 1.
- the plurality of nozzle headers 4 control at least one of the flow rate and the flow velocity of the cooling gas in the width direction of the steel strip 1.
- Each of the plurality of nozzle headers 4 has a plurality of nozzles 5 provided at prescribed intervals in the longitudinal direction of the nozzle header 4.
- 6 is a duct for supplying a cooling gas from a cooling gas reservoir not shown to each of the nozzle headers 4.
- Each of a plurality of branch pipes 7 branching from the duct 6 is connected to each of the plurality of headers 4.
- a blower 8 and a cooler 9 for cooling the cooling gas flowing through the duct 6 are provided in the middle of the duct 6, and a control valve 10 is provided in the middle of each of the branch pipes 7.
- the steel strip 1 continuously travels in the direction as shown by the arrow in Fig. 38 while coming into contact with each of the above-mentioned plurality of cooling rolls 2. In the meantime, the portion of the surface of the steel strip 1 coming into contact with the surface of each of the cooling rolls 2 is cooled.
- the steel strip 1 cooled by each of the plurality of cooling rolls 2 to a prescribed temperature is then introduced into the gas cooler 3, in which the cooling gas is blown from each of the plurality of nozzle headers 4 so as to achieve a uniform temperature distribution in the width direction of the steel strip 1 after the final cooling thereof.
- At least one of the flow rate and the flow velocity of the cooling gas is controlled by means of the control valve 10 provided in the middle of each of the plurality of branch pipes 7.
- Fig. 40 is a graph illustrating a temperature distribution of the same steel strip 1 as that of the prior art 1 in the width direction thereof, when continuously cooling the steel strip 1 from the cooling start temperature of about 600°C to the target temperature for cooling of 350°C by means of the apparatus according to the prior art 2 as shown in Fig. 38.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof, and the ordinate represents a temperature of the steel strip 1 in the width direction thereof.
- the solid line represents the temperature of the steel strip 1 on the exit side of each of five cooling rolls 2a to 2e
- the dotted line represents a temperature of the steel strip 1 in the width direction thereof.
- the temperature of the steel strip 1 in the width direction thereof on the exit side of the cooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 100 mm from the side edge of the steel strip 1, and is about 570°C at a position, for example, of 20 mm from the side edge of the steel strip 1.
- the steel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edge to the center of the steel strip 1, as shown by the dotted line in Fig. 40.
- Fig. 41 is a graph illustrating an aging index (AI) of the above-mentioned steel strip 1.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of the steel strip 1 in the width direction thereof.
- the portion showing an aging index of over 4 kgf/mm2 covers about 80 mm from a side edge of the steel strip 1.
- An object of the present invention is therefore to provide, when continuously cooling a metal strip continuously travelling in the longitudinal direction thereof by means of at least one cooling roll and a gas cooler, an apparatus for continuously cooling a metal strip, which permits prevention of the occurrence of a defect such as edge waves, heat buckles or scratches in the metal strip and an abnormal travelling of the metal strip such as a zigzag motion in the next process, requires only limited installation and running costs of the gas cooler, and makes available a high-quality metal strip having uniform mechanical properties in the width direction thereof, through achievement of a uniform temperature distribution of the metal strip in the width direction thereof.
- an apparatus for continuously cooling a metal strip which comprises: at least one cooling roll, which is freely rotatable and in contact with a metal strip continuously travelling in the longitudinal direction thereof, for continuously cooling said metal strip, said cooling roll having a length at least equal to the width of said metal strip, a cooling liquid flowing through the interior of said cooling roll to continuously cool same, and a contact area between the surface of said cooling roll and the surface of said metal strip being controllable; and a gas cooler, arranged on the exit side of said at least one cooling roll, for continuously cooling said metal strip by blowing a cooling gas onto the surface of said metal strip so as to achieve a uniform temperature distribution in the width direction of said metal strip after the final cooling thereof, said gas cooler being arranged in the width direction of said metal strip at a prescribed distance from each of the both surfaces of said metal strip, said gas cooler comprising a plurality of mutually independent nozzle headers for blowing said cooling gas onto the surface of said metal strip, and said plurality of
- the present invention was made on the basis of the above-mentioned findings.
- the apparatus of the present invention is described below with reference to the drawings as to the continuous cooling of a steel strip.
- Fig. 1 is a descriptive view illustrating a first embodiment of the apparatus of the present invention.
- the apparatus of the first embodiment comprises a plurality of cooling rolls 2, which are freely rotatable and in contact with a steel strip 1 continuously travelling in the longitudinal direction thereof, for continuously cooling the steel strip 1, a gas cooler 3, arranged on the exit side of the plurality of cooling rolls 2, for continuously cooling the steel strip 1 by blowing a cooling gas onto the surface of the steel strip 1 so as to achieve a uniform temperature distribution in the width direction of the steel strip 1 after the final cooling thereof, a first tension regulator 17, comprising at least two bridle rolls, arranged on the entry side of the plurality of cooling rolls 2, and a second tension regulator 18, comprising at least two bridle rolls, arranged on the exit side of the gas cooler 3.
- 19 are deflector rolls, each installed on each of the entry side and the exit side of the gas cooler 3, for keeping a clearance of the steel strip 1 travelling through the gas cooler 3 from the gas cooler 3.
- the plurality of cooling rolls 2 are arranged with the axes thereof in parallel with each other at prescribed intervals. Each of the plurality of cooling rolls 2 has a length at least equal to the width of the steel strip 1. A cooling liquid flows through the interior of each of the cooling rolls 2 to continuously cool same. Each of the plurality of cooling rolls 2 is displaceable toward the steel strip 1 by a driving mechanism not shown to control the contact area between the surface of each of the cooling rolls 2 and the surface of the steel strip 1.
- the gas cooler 3 is arranged in the width direction of the steel strip 1 at a prescribed distance from each of the both surfaces of the steel strip 1 continuously travelling in the longitudinal direction thereof.
- the gas cooler 3 shown in Fig. 39 according to the prior art 2 may be used also in the apparatus of the present invention.
- the gas cooler 3 comprises a plurality of mutually independent nozzle headers 4 for blowing a cooling gas onto the surface of the steel strip 1.
- the plurality of nozzle headers 4 control at least one of the flow rate and the flow velocity of the cooling gas in the width direction of the steel strip.
- Each of the plurality of nozzle headers 4 has a plurality of nozzles 5 provided at prescribed intervals in the longitudinal direction of the nozzle header 4.
- the nozzle 5, which is hole-shaped in 39, may be slit-shaped.
- 6 is a duct for supplying a cooling gas from a cooling gas reservoir not shown to each of the nozzle headers 4.
- Each of a plurality of branch pipes 7 branching from the duct 6 is connected to each of the plurality of headers 4.
- a blower 8 and a cooler 9 for cooling the cooling gas flowing through the duct 6 are provided in the middle of the duct 6, and a control valve 10 is provided in the middle of each of the branch pipes 7.
- Fig. 2 is a flow diagram illustrating a typical cooling system using the apparatus of the first embodiment of the present invention.
- a thermometer 11 for continuously measuring a temperature distribution in the width direction of the steel strip 1 after the final cooling thereof is provided on the exit side of the gas cooler 3.
- Target temperature in the width direction of the steel strip 1 after the final cooling thereof, are stored in a computer 12.
- the thermometer 11 continuously measures the temperature distribution in the width direction of the steel strip 1 after the final cooling thereof, and transmits the result of measurement to a first comparator 13.
- the first comparator 13 compares the result of measurement transmitted from the thermometer 11 with the target temperature in the width direction of the steel strip 1 after the final cooling thereof transmitted from the computer 12, and calculates the difference therebetween.
- the first comparator 12 transmits a signal for controlling at least one of a flow rate and a flow velocity of the cooling gas in the width direction of the steel strip 1 to the control valve 10 provided in the middle of each of the plurality of branch pipes 7 so that the difference as calculated above becomes null. At least one of the flow rate and the flow velocity of the cooling gas blown from each of the plurality of nozzle headers 4 of the gas cooler 3 onto the surface of the steel strip 1 is thus controlled in the width direction of the steel strip 1 so as to achieve a uniform temperature distribution in the width direction of the steel strip 1 after the final cooling thereof.
- the computer 12 stores also cooling conditions by the gas cooler 3 for each of a thickness, a heat treatment cycle (including a cooling start temperature, a cooling rate and a target temperature for cooling) and a travelling speed of the steel strip 1.
- a change commander 14 transmits a change signal of the cooling conditions to a second comparator 15 based on a signal from the computer 12.
- a seam position detector 16 detects, on the other hand, a seam position of the steel strip 1, for which the thickness or the travelling speed has been changed, and transmits a detection signal to the second comparator 15.
- the second comparator 15 transmits a signal to the blower 8 and the cooler 9 to control at least one of the flow rate and the flow velocity of the cooling gas blown by the blower 8 and the cooling conditions of the cooling gas by the cooler 9. This regulates the amount of cooling of the steel strip 1 by the gas cooler 3.
- Fig. 3 is a schematic perspective view illustrating another typical gas cooler used in the apparatus of the present invention.
- the gas cooler 3 may comprise, for example, three nozzle headers 4a, 4b and 4c, which are selectively movable in the width direction of the steel strip 1.
- the gas cooler 3 has such a construction, it is possible to cope with a change in the width of the steel strip 1 or a zigzag motion of the steel strip 1.
- the first tension regulator 17 is arranged on the entry side of the plurality of cooling rolls 2, and the second tension regulator 18 is arranged on the exit side of the gas cooler 3.
- a desired tension is therefore imparted to the steel strip 1 continuously travelling through the plurality of cooling rolls 2 and the gas cooler 3. This reduces the occurrences of a defective contact between the surface of the steel strip 1 and the surface of each of the plurality of cooling rolls 2, and the occurrences of scratches in the steel strip 1 caused by the contact with the gas cooler 3 during travelling through the gas cooler 3.
- Fig. 4 is a graph illustrating the relationship between a tension of the steel strip 1 continuously travelling while coming into contact with each of the plurality of cooling rolls 2 and a height of an upward warp of the steel strip 1 at the side edge portion in the width direction thereof from the surface of each of the cooling rolls 2.
- the abscissa represents a tension acting on the steel strip 1
- the ordinate represents a height of an upward warp of the steel strip 1 at the side edge portion thereof from the surface of the cooling roll 1.
- the difference in temperature between the both side edges of the steel strip 1 in the width direction thereof and the center portion of the steel strip 1 on the exit side of the plurality of cooling rolls 2 is reduced.
- This permits saving of the blowing time of the cooling gas and the quantity of the blown cooling gas onto the surface of the steel strip 1 by the gas cooler 3 for achieving a uniform temperature distribution in the width direction of the steel strip 1 after the final cooling thereof.
- the installation and running costs of the gas cooler 3 are largely reduced as compared with the apparatus of the prior art 2.
- Fig. 5 is a graph illustrating the relationship between a tension of the steel strip 1 continuously travelling through the gas cooler 3 and a rate of occurrence of scratches on the steel strip 1 caused by the contact of the steel strip 1 with the gas cooler 3.
- the abscissa represents acting on the steel strip 1
- the ordinate represents a rate of occurrence of scratches on the steel strip 1.
- the curve "a” represents the rate of occurrence of scratches with a clearance of 75 mm between the steel strip 1 and the gas cooler 3
- the curve "b” represents the rate of occurrence of scratches with a clearance of 150 mm between the steel strip 1 and the gas cooler 3.
- the rate of occurrence of scratches on the steel strip 1 is decreased according as the tension of the steel strip 1 continuously travelling is increased.
- the tension of the steel strip 1 is increased to at least 3 kg/mm2
- almost no scratches are caused on the steel strip 1 even if the clearance between the steel strip 1 and the gas cooler 3 is reduced to 75 mm. It is thus possible to reduce the clearance between the steel strip 1 and the gas cooler 3 without causing scratches on the steel strip 1 by increasing the tension of the steel strip 1 continuously travelling through the gas cooler 3, thus improving the cooling effect by the gas cooler 3.
- the contact area between the surface of the steel strip 1 and the surface of each of the first-half cooling rolls 2a, 2b and 2c from among the plurality of cooling rolls 2 should preferably be larger than the contact area between the surface of the steel strip 1 and the surface of each of the latter-half cooling rolls 2d and 2e from among the plurality of cooling rolls 2.
- the contact area between the surface of the steel strip 1 and the surface of each of the plurality of cooling rolls 2 can be controlled by causing each of the plurality of cooling rolls 2 to displace toward the steel strip 1.
- Fig. 6 is a graph illustrating an amount of temperature drop of the steel strip 1 at each of the plurality of cooling rolls 2a, 2b, 2c, 2d and 2e, when continuously cooling the steel strip 1 by means of the apparatus of the first embodiment of the present invention as shown in Fig. 1.
- a larger contact area between the surface of-the steel strip 1 and the surface of each of the first-half cooling rolls 2a, 2b and 2c results in a larger amount of temperature drop ( ⁇ T) of the steel strip 1 at each of the first-half cooling rolls 2a, 2b and 2c. This reduces the degree of unevenness of the temperature distribution of the steel strip 1 in the width direction thereof on the exit side of the cooling roll 2e.
- both side edge portions of the steel strip 1 in the width direction thereof on the exit side of the final cooling roll 2e therefore form an upward warp largely apart from the surface of the final cooling rolls 2e, and thus, the both side edge portions of the steel strip 1 have a higher temperature than that of the center portion thereof.
- the contact area between the surface of the steel strip 1 and the surface of each of the plurality of cooling rolls 2a, 2b, 2c, 2d and 2e may be gradually increased from the downstream cooling roll 2e toward the upstream cooling roll 2a.
- Fig. 7 is a graph illustrating a temperature distribution of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 under the same conditions as in the prior art 2 by means of the apparatus of the first embodiment of the present invention as shown in Fig. 1.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof and the ordinate represents a temperature of the steel strip 1 in the width direction thereof.
- the temperature of the steel strip 1 in the width direction thereof on the exit side of the cooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 50 mm from the side edge of the steel strip 1, and is about 480°C at a position, for example, of 20 mm from the side edge of the steel strip 1.
- the steel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edged to the center of the steel strip 1, as shown by the dotted line in Fig. 7.
- the one-point chain line in Fig. 7 represents a temperature distribution of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 by means of the above-mentioned prior art 1, i.e., by means of the plurality of cooling rolls 2 alone.
- the two-point chain line in Fig. 7 represents a temperature distribution of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 by means of the plurality of cooling rolls 2 alone, with however two tension regulators each provided on the entry side and the exit side of the plurality of cooling rolls 2.
- cooling of the steel strip 1 by means of the apparatus of the first embodiment of the present invention permits achievement of a uniform temperature distribution of the steel strip 1 in the width direction thereof as compared with the prior art 1.
- Fig. 8 is a graph illustrating an aging index (AI) of the above-mentioned steel strip 1 in the width direction thereof.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof and the ordinate represents an aging index (AI) of the steel strip 1 in the width direction thereof.
- AI aging index
- the portion showing an aging index of over 4 kgf/mm2 covers only about 30 mm from the side edge of the steel strip 1, thus the portion having an aging index of over 4 kgf/mm2 is remarkably reduced as compared with the prior arts 1 and 2.
- the one-point chain line in Fig. 8 represents an aging index of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 by means of the above-mentioned prior art 1, i.e., by means of the plurality of cooling rolls 2 alone.
- the two-point chain line in Fig. 8 represents an aging index of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 by means of the plurality of cooling rolls 2 alone, with however two tension regulators each provided on the entry side and the exit side of the plurality of cooling rolls 2.
- cooling of the steel strip 1 by means of the apparatus of the first embodiment of the present invention permits achievement of a uniform aging index of the steel strip 1 in the width direction thereof as compared with the prior art 1.
- the aging index of the steel strip 1 in the width direction thereof becomes uniform even as compared with the prior art 2.
- Fig. 9 is a schematic side view illustrating a typical apparatus of the first embodiment of the present invention.
- the first tension regulator 17 comprising at least two bridle rolls is arranged on the entry side of the plurality of cooling rolls 2
- the second tension regulator 18 comprising at least two bridle rolls is arranged on the exit side of the gas cooler 3.
- a thermometer 11 for continuously measuring a temperature distribution in the width direction of the steel strip 1 after the final cooling thereof is provided on the exit side of the gas cooler 3.
- the deflector roll 19 is provided on each of the entry side and the exit side of the gas cooler 3.
- 20 is a blower, driven by a motor 21, for blowing a cooling gas through a duct 23 into the gas cooler 3, and 22 is a cooler for cooling the cooling gas.
- the blower 20, the cooler 22, the duct 23 and the gas cooler 3 are housed in a gas cooling chamber 24 shield from the open air. Slots 26 and 26' for passing the steel strip 1 are provided on each of the entry side and the exit side of the gas cooling chamber 24.
- a dumper not shown is provided in the middle of the duct 23, for controlling in the width direction of the steel strip 1 at least one of the flow rate and the flow velocity of the cooling gas in the width direction of the steel strip 1.
- the steel strip 1 continuously travelling in the longitudinal direction thereof, which has been slowly cooled to a prescribed temperature in a preliminary cooling zone 25, is introduced through the first tension regulator 17 to the plurality of cooling rolls 2.
- the steel strip 1 is then cooled by the contact with each of the plurality of cooling rolls 2.
- the steel strip 1 is introduced through a slot 26 into the gas cooling chamber 24.
- the steel strip 1 is cooled in the gas cooler 3 in the gas cooling chamber 24 so as to achieve a uniform temperature distribution in the width direction of the steel strip 1 after the final cooling thereof.
- the steel strip 1 cooled in the gas coller 3 leaves the gas cooling chamber 24 through another slot 26' and directed through the second tension regulator 18 to the next treatment process.
- At least one of the flow rate and the flow velocity of the cooling gas which is blown onto the surface of the steel strip 1 is controlled by the dumper not shown, provided in the middle of the duct 23.
- a mixed gas which comprises a hydrogen gas of from 40 to 90 vol.% and a nitrogen gas of from 10 to 60 vol.%, and has a large amount of heat transfer per unit time.
- Fig. 10 is a graph illustrating, in a cooling gas comprising a mixed gas of hydrogen gas and nitrogen gas, the relationship between a hydrogen gas content in the cooling gas and an amount of heat transfer per unit time of the cooling gas.
- a hydrogen gas content in the above-mentioned cooling gas of under 40 vol.% or over 90 vol.% leads to a decreased amount of heat transfer per unit time of the cooling gas.
- the most desirable hydrogen gas content in the cooling gas is about 70 vol.%.
- the hydrogen gas content in the cooling gas is adjusted when changing the thickness, the heat treatment cycle or the travelling speed of the steel strip 1.
- the hydrogen gas content in the cooling gas may be changed in the width direction of the steel strip 1 so as to control the cooling conditions of the steel strip 1 in the width direction thereof.
- a helium gas may be employed in place of a hydrogen gas.
- Fig. 11 is a descriptive view illustrating a second embodiment of the apparatus of the present invention.
- the apparatus of the second embodiment is identical with the apparatus of the first embodiment shown in Fig. 1, except that another gas cooler 27 for continuously cooling the steel strip 1 by blowing a cooling gas onto the surface of the steel strip 1 so as to achieve a uniform temperature distribution in the width direction of the steel strip 1 after the final cooling thereof, is arranged between the first tension regulator 17 and the plurality of cooling rolls 2.
- Fig. 12 is a graph illustrating a temperature distribution of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 under the same conditions as in the first embodiment by means of the apparatus of the second embodiment of the present invention as shown in Fig. 11.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof
- the ordinate represents a temperature of the steel strip 1 in the width direction thereof.
- the temperature of the steel strip 1 in the width direction thereof on the exit side of the cooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 50 mm from the side edge of the steel strip 1.
- the steel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edge to the center of the steel strip 1, as shown by the dotted line in Fig. 16.
- Fig. 13 is a graph illustrating an aging index (AI) of the above-mentioned steel strip 1 in the width direction thereof.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of the steel strip 1 in the width direction thereof.
- the portion showing an aging index of over 4 kgf/mm2 covers only about 30 mm from the side edge of the steel strip 1, with a maximum aging index of 4.8 kgf/mm2, thus the portion having an aging index of over 4 kgf/mm2 is remarkably reduced as compared with the prior arts 1 and 2.
- Fig. 14 is a descriptive view illustrating a third embodiment of the apparatus of the present invention.
- the apparatus of the third embodiment is identical with the apparatus of the first embodiment shown in Fig. 1, except that another gas cooler 28 for continuously cooling the steel strip 1 by blowing a cooling gas onto the surface of the steel strip 1 so as to achieve a uniform temperature distribution in the width direction of the steel strip 1 after the final cooling thereof, is arranged in the middle portion of the plurality of cooling rolls 2, i.e., between the first-half cooling rolls 2a, 2b and 2c and the latter-half cooling rolls 2d and 2e.
- Fig. 15 is a graph illustrating a temperature distribution of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 under the same conditions as in the first embodiment by means of the apparatus of the third embodiment of the present invention as shown in Fig. 14.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof
- the ordinate represents a temperature of the steel strip 1 in the width direction thereof.
- the temperature of the steel strip 1 in the width direction thereof on the exit side of the cooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 50 mm from the side edge of the steel strip 1.
- the steel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edge to the center of the steel strip 1, as shown by the dotted line in Fig. 15.
- the one-point chain line in Fig. 15 represents a temperature of the steel strip 1 on the exit side of the another gas cooler 28.
- Fig. 16 is a graph illustrating an aging index (AI) of the above-mentioned steel strip 1 in the width direction thereof.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of the steel strip 1 in the width direction thereof.
- the portion showing an aging index of over 4 kgf/mm2 covers only about 40 mm from the side edge of the steel strip 1, with a maximum aging index of 4.8 kgf/mm2, thus the portion having an aging index of over 4 kgf/mm2 is remarkably reduced as compared with the prior arts 1 and 2.
- Fig. 17 is a descriptive view illustrating a fourth embodiment of the apparatus of the present invention.
- the apparatus of the fourth embodiment is identical with the apparatus of the first embodiment shown in Fig. 1, except that another gas cooler 27 for continuously cooling the steel strip 1 by blowing a cooling gas onto the surface of the steel strip 1 so as to achieve a uniform temperature distribution in the width direction of the steel strip 1 after the final cooling thereof, is arranged between the first tension regulator 17 and the plurality of cooling rolls 2, and further another gas cooler 28 for continuously cooling the steel strip 1 by blowing a cooling gas onto the surface of the steel strip 1 so as to achieve a uniform temperature distribution in the width direction of the steel strip 1 after the final cooling thereof, is arranged in the middle portion of the plurality of cooling rolls 2, i.e., between the first-half cooling rolls 2a, 2b and 2c and the latter-half cooling rolls 2d and 2e.
- Fig. 18 is a graph illustrating a temperature distribution of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 under the same conditions as in the first embodiment by means of the apparatus of the fourth embodiment of the present invention as shown in Fig. 17.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof
- the ordinate represents a temperature of the steel strip 1 in the width direction thereof.
- the temperature of the steel strip 1 in the width direction thereof on the exit side of the cooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 50 mm from the side edge of the steel strip 1.
- the steel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edge to the center of the steel strip 1, as shown by the dotted line in Fig. 18.
- the one-point chain line in Fig. 18 represents a temperature of the steel strip 1 on the exit side of the further another gas cooler 28.
- Fig. 19 is a graph illustrating an aging index (AI) of the above-mentioned steel strip 1 in the width direction thereof.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of the steel strip 1 in the width direction thereof.
- the portion showing an aging index of over 4 kgf/mm2 covers only about 35 mm from the side edge of the steel strip 1, with a maximum aging index of 4.8 kgf/mm2, thus the portion having an aging index of over 4 kgf/mm2 is remarkably reduced as compared with the prior arts 1 and 2.
- Fig. 20 is a descriptive view illustrating a fifth embodiment of the apparatus of the present invention.
- the apparatus of the fifth embodiment is identical with the apparatus of the first embodiment shown in Fig. 1, except that a plurality of gas blowing nozzles 29, which are directed toward a contact face between the surface of each of the plurality of cooling rolls 2 and the surface of the steel strip 1, are provided on the side of the cooling rolls 2.
- the plurality of gas blowing nozzles 29 are provided stationarily or displaceably in the longitudinal direction of each of the cooling rolls 2, at prescribed intervals in the longitudinal direction of each of the cooling rolls 2.
- Each of the plurality of gas blowing nozzles 29 continuously cools the steel strip 1 by blowing a cooling gas onto the surface of the steel strip 1 so as to achieve a uniform temperature distribution in the width direction of the steel strip 1 after the final cooling thereof.
- shallow grooves 30 for passing the blown cooling gas should preferably be provided on the surface of each of the plurality of cooling rolls 2 used in the apparatus of the fifth embodiment.
- Fig. 22 is a graph illustrating a temperature distribution of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 under the same conditions as in the first embodiment by means of the apparatus of the fifth embodiment of the present invention as shown in Fig. 20.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof
- the ordinate represents a temperature of the steel strip 1 in the width direction thereof.
- the temperature of the steel strip 1 in the width direction thereof on the exit side of the cooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 55 mm from the side edge of the steel strip 1.
- the steel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edge to the center of the steel strip 1, as shown by the dotted line in Fig. 22.
- Fig. 23 is a graph illustrating an aging index (AI) of the above-mentioned steel strip 1 in the width direction thereof.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of the steel strip 1 in the width direction thereof.
- the portion showing an aging index of over 4 kgf/mm2 covers only about 35 mm from the side edge of the steel strip 1, with a maximum aging index of 5.0 kgf/mm2, thus the portion having an aging index of over 4 kgf/mm2 is remarkably reduced as compared with the prior arts 1 and 2.
- Fig. 24 is a descriptive view illustrating a sixth embodiment of the apparatus of the present invention.
- the apparatus of the sixth embodiment is identical with the apparatus of the first embodiment shown in Fig. 1, except that a plurality of gas blowing nozzles 31, which are directed toward a contact face between the surface of each of the plurality of cooling rolls 2 and the surface of the steel strip 1, are provided on the side of the steel strip 1.
- Fig. 25 is a schematic side view illustrating a typical apparatus of the sixth embodiment of the present invention.
- each of the plurality of gas blowing nozzles 31 comprises an arcuate nozzle header 32, provided on the side of the steel strip 1 toward a contact face between the surface of each of the plurality of cooling rolls 2 and the surface of the steel strip 1, and a plurality of nozzles 33 provided at prescribed intervals on each of the arcuate nozzle headers 32.
- Each of the arcuate nozzle headers 32 is displaceable toward the steel strip 1 by means of, for example, an air cylinder 34 so that a gap between the steel strip 1 and the gas blowing nozzle 31 can be adjusted.
- Each of the gas blowing nozzles 31 having such a construction is provided stationarily or displaceably in the longitudinal direction of each of the cooling rolls 2 at a prescribed interval.
- the apparatus of the sixth embodiment is identical with the apparatus of the first embodiment in that the gas cooler 3 is arranged on the exit side of the plurality of cooling rolls 2, the first tension regulator 17 is arranged on the entry side of the plurality of cooling rolls 2, and the second tension regulator 18 is arranged on the exit side of the gas cooler 3.
- a radiation thermometer 11a and a multiple reflection thermometer 11b as the thermometer 11 are provided on each of the entry side of the first tension regulator 17 and the exit side of the second tension regulator 18.
- a temperature distribution in the width direction of the steel strip 1 after the final cooling thereof, is continuously measured by means of the radiation thermometer 11a and the multiple reflection thermometer 11b provided on the exit side of the second tension regulator 18.
- the deflector roll 19 is provided on each of the entry side and the exit side of the gas cooler 3.
- 58 is a sealing roll provided at each of the entry and the exit of the gas cooler 3
- 59 is a movable partition plate.
- Fig. 26 is a descriptive view illustrating the functions of the radiation thermometer 11a and the multiple reflection thermometer 11b as the thermometer 11.
- the radiation thermometer 11a measures a radiation temperature of the steel strip 1 in the width direction thereof.
- the multiple reflection thermometer 11b measures a true temperature of the steel strip 1 on the surface thereof which is in contact with a roll.
- the true temperature of the steel strip 1 measured by the multiple reflection thermometer 11b is transmitted to a computer 60.
- the radiation temperature of the steel strip 1 measured by the radiation thermometer 11a is on the other hand transmitted to a thermal emissivity corrector 61.
- the thermal emissivity corrector 61 corrects the measured value of the radiation temperature of the steel strip 1 in the width direction thereof on the basis of the true temperature of the steel strip 1 transmitted from the computer 60.
- the thus corrected radiation temperature of the steel strip 1 in the width direction thereof is transmitted, for example, to the first comparator 13 shown in Fig. 2.
- Fig. 27 is a graph illustrating a temperature distribution of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 under the same conditions as in the first embodiment by means of the apparatus of the sixth embodiment of the present invention as shown in Fig. 24.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof, and the ordinate represents a temperature of the steel strip 1 in the width direction thereof.
- the temperature of the steel strip 1 in the width direction thereof on the exit side of the cooling roll 2e is about 380°C at the side edge of the steel strip 1, and is substantially equal to the target temperature for cooling of 350°C at a portion of about 10 mm from the side edge of the steel strip 1.
- the temperature of the steel strip 1 in the width direction thereof decreases to slightly lower than the target temperature for cooling of 350°C at a position of about 10 mm from the side edge of the steel strip 1.
- Fig. 28 is a graph illustrating an aging index (AI) of the above-mentioned steel strip 1 in the width direction thereof.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of the steel strip 1 in the width direction thereof.
- AI aging index
- Fig. 29 is a descriptive view illustrating a seventh embodiment of the apparatus of the present invention.
- the apparatus of the seventh embodiment is identical with the apparatus of the first embodiment shown in Fig. 1, except that a third tension regulator 35 comprising at least two bridle rolls is further arranged between the plurality of cooling rolls 2 and the gas cooler 3.
- a temperature distribution and an aging index (AI) of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 by means of the apparatus of the seventh embodiment, is substantially the same as in the apparatus of the first embodiment shown in Fig. 1, and a detailed description thereof is omitted.
- Fig. 30 is a descriptive view illustrating an eighth embodiment of the apparatus of the present invention.
- the apparatus of the eighth embodiment comprises a single cooling roll 36, which is freely rotatable and in contact with a steel strip 1 continuously travelling in the logitudinal direction thereof, for continuously cooling the steel strip 1, a gas cooler 3, arranged on the exit side of the single cooling roll 36, for continuously cooling the steel strip 1 by blowing a cooling gas onto the surface of the steel strip 1 so as to achieve a uniform temperature distribution in the width direction of the steel strip 1 after the final cooling thereof, a first tension regulator 17, comprising at least two bridle rolls, arranged on the entry side of the single cooling roll 36, and a second tension regulator 18, comprising at least two bridle rolls, arranged on the exit side of the gas cooler 3.
- the single cooling roll 36 is stationary relative to the steel strip 1.
- the single cooling roll 36 has a length at least equal to the width of the steel strip 1, and a cooling liquid flows through the interior of the single cooling roll 36 to continuously cool the single cooling roll 36.
- a guide roll 37 for controlling a contact area between the surface of the single cooling roll 36 and the surface of the steel strip 1, is provided on each of the entry side and the exit side of the single cooling roll 36.
- Each of the guide rolls 37 is displaceable along the outer periphery of the single cooling roll 36 by means of a driving mechanism not shown. It is possible to control the contact area between the surface of the single cooling roll 36 and the surface of the steel strip 1, by causing each of the guide rolls 37 to displace along the outer periphery of the single cooling rolls 36.
- Fig. 31 is a graph illustrating a temperature distribution of a steel strip 1 in the width direction thereof, when continuously cooling the steel strip 1 under the same conditions as in the first embodiment by means of the apparatus of the eighth embodiment of the present invention as shown in Fig. 30.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof
- the ordinate represents a temperature of the steel strip 1 in the width direction thereof.
- the temperature of the steel strip 1 in the width direction thereof on the exit side of the single cooling roll 36 is over the target temperature for cooling of 350°C in a portion within about 10 mm from the side edge of the steel strip 1.
- the steel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edge to the center of the steel strip 1, as shown by the dotted line in Fig. 31.
- Fig. 32 is a graph illustrating an aging index (AI) of the above-mentioned steel strip 1 in the width direction thereof.
- the abscissa represents a distance from the side edge of the steel strip 1 toward the center in the width direction thereof
- the ordinate represents an aging index (AI) of the steel strip 1 in the width direction thereof.
- the portion showing an aging index of over 4 kgf/mm2 covers only about 10 mm from the side edge of the steel strip 1, with a maximum aging index of 4.5 kgf/mm2, thus the portion having an aging index of over 4 kgf/mm2 is remarkably reduced as compared with the prior arts 1 and 2.
- Figs. 33(A) and 33(B) are flow diagrams illustrating a typical continuous annealing equipment of a steel strip incorporating the apparatus of the first embodiment of the present invention.
- an entry side looper 40 As shown in Figs. 33(A) and 33(B), an entry side looper 40, a preheating zone 41, a direct heating zone 42, an indirect heating zone 43, a soaking zone 44, a slow cooling zone 45, a first cooling zone 46 comprising the apparatus of the first embodiment of the present invention, an overaging zone (or a tempering zone; the same applies also hereafter) 47, a second cooling zone 48, and an exit side looper 49 are arranged in this order between a plurality of uncoilers 38 and a plurality of coilers 39.
- first cooling zone 46 comprising the apparatus of the first embodiment of the present invention, there are arranged a first tension regulator 17, a plurality of cooling rolls 2, a gas cooler 3, and a second tension regulator 18 in this order.
- a chemical pretreatment zone 54 for forming a film of nickel or a nickel alloy in a slight amount and an oxide film in a slight amount on the surface of the continuously annealed steel strip 1 to improve chemical treatability and/or lubricity of the steel strip 1.
- a temper rolling mill 55 for forming a film of nickel or a nickel alloy in a slight amount and an oxide film in a slight amount on the surface of the continuously annealed steel strip 1 to improve chemical treatability and/or lubricity of the steel strip 1.
- the steel strip 1, the shape of which has been levelled by the leveller 53, is introduced through the entry side looper 40 sequentially into the preheating zone 41, the direct heating zone 42, the indirect heating zone 43, the soaking zone 44 and the slow cooling zone 45.
- the steel strip 1 is preheated, directly heated, indirectly heated, soaked, and then slowly cooled in accordance with a prescribed heat cycle.
- the steel strip 1 is uniformly heated to a prescribed temperature with only a few irregularities in heating or thermal deformations.
- the steel strip 1 since the steel strip 1 is rapidly heated in the above-mentioned direct heating zone 42, the steel strip 1 passes through an unstable thermal deformation region in a very short period of time. Therefore, the steel strip 1 is less susceptible to the thermal deformation tending to occur during heating, and a zigzag motion of the steel strip 1 travelling through the direct heating zone 42 is prevented.
- the steel strip 1 slowly cooled to a prescribed temperature in the slow cooling zone 45 is then introduced into the first cooling zone 46, in which the steel strip 1 is continuously cooled by the plurality of cooling rolls 2, and then continuously cooled by the gas cooler 3 so as to achieve a uniform temperature distribution in the width direction of the steel strip 1 afrer the final cooling thereof. Because the steel strip 1 has been levelled into a flat shape by the leveller 53, an insufficient contact of the steel strip 1 with the plurality of cooling rolls 2 is prevented.
- the steel strip 1 cooled to a prescribed temperature in the first cooling zone 46 is then introduced into the overaging zone 47, in which an overaging treatment is applied to the steel strip 1. Since the steel strip 1 has been cooled in the above-mentioned first cooling zone 46 so as to achieve a uniform temperature distribution in the width direction of the steel strip 1 after the final cooling thereof, a defective shape such as edge waves or heat buckles does not occur in the steel strip 1, and as a result, an abnormal travelling such as a zigzag motion never occurs in the steel strip 1 which travels through the overaging zone 47 as the next process.
- the steel strip 1 overaged in the overaging zone 47 and cooled to a temperature not causing oxidation in the second cooling zone 48 is then introduced into the chemical pretreatment zone 54, in which a film of nickel or a nickel alloy in a slight amount is formed on the surface of the steel strip 1 through a cathodic electrolysis treatment, and then, an oxide film in a slight amount is formed on the nickel or nickel alloy film through a dipping treatment in a neutral or alkaline bath.
- Figs. 34(A), 34(B) and 34(C) are schematic flow diagrams each illustrating a typical chemical pretreatment zone 54.
- the chemical pretreatment zone 54 comprises a cooling tank 62, a pickling tank 63, a water rinsing tank 64, a nickel-phosphorus alloy plating tank 65, another water rinsing tank 64, a scrubber 66, a neutralizing tank 67, another scrubber 66, a hot water tank 68, and a cold water tank 69.
- the steel strip 1 is introduced through the cooling tank 62, the pickling tank 63 and the water rinsing tank 64 into the nickel-phosphorus alloy plating tank 65, in which a nickel-phosphorus alloy film in a slight amount is formed on the surface of the steel strip 1 through a cathodic electrolysis treatment.
- the steel strip 1 on the surface of which the nickel-phosphorus alloy plating film has thus been formed is then introduced through the another water rinsing tank 64, the scrubber 66, the neutralizing tank 67 and the another scrubber 66 into the hot water tank 68 and the cold water tank 69, in which an oxide film in a slight amount is formed on the nickel-phosphorus alloy plating film.
- Fig. 34(B) is identical with that shown in Fig. 34(A), except that a nickel plating tank 70 is provided in place of the above-mentioned nickel-phosphorus alloy plating tank 65.
- Fig. 34(C) is identical with that shown in Fig. 34(B), except that a water spray tank 71 is provided in place of the above-mentioned scrubber 66 and neutralizing tank 67.
- the continuously annealed steel strip 1 has a beautiful surface as a result of a direct flame reducing heating applied in the direct heating zone 42, a heating in a weakly reducing atmosphere applied in the indirect heating zone 43 and the soaking zone 44, and a non-oxidizing cooling applied in the first cooling zone 46.
- the steel strip 1 is not always satisfactory in chemical treatability and/or lubricity. This problem is solved by forming a nickel or nickel alloy film in a slight amount and an oxide film in a slight amount on the surface of the steel strip 1 in the chemical pretreatment zone 54 as described above, thus permitting improvement of chemical treatability and/or lubricity of the steel strip 1.
- the steel strip 1 to which the above-mentioned pretreatment has been applied in the chemical pretreatment zone 54 is then introduced through the exit side looper 49 into the temper rolling mill 55, in which a temper rolling is applied to the steel strip 1. Then, the side edges of the steel strip 1 are trimmed by the trimmer 56. After application of an anticorrosive oil by the oiler 57, the steel strip 1 is coiled by any one of the coilers 39 into a coil.
- the steel strip 1 after the final cooling thereof in the above-mentioned process has a uniform temperature distribution in the width direction thereof, the steel strip 1 has substantially a uniform aging index in the width direction thereof. It is therefore possible to manufacture a steel strip 1 having uniform mechanical properties and excellent in quality.
- the apparatus of the present invention is applicable also, for example, for the cooling when continuously hardening or tempering a steel strip comprising a high tensile steel, the cooling when continuously annealing a steel strip comprising an aluminum-killed steel containing at least one of titanium, niobium, zirconium, vanadium and boron in a slight amount to fix carbon or nitrogen in steel, the cooling applied to a continuously annealed steel strip on the entry side of a hot-dip plating tank in a continuous hot-dip plating equipment, and the cooling applied to a hot-dip plated steel strip on the exit side of a hot-dip plating tank.
- an apparatus for continuously cooling a metal strip which permits prevention of the occurrence of a defect such as edge waves, heat buckles or scratches in the metal strip and an abnormal travelling of the metal strip such as a zigzag motion in the next process, requires only limited installation and running costs of the gas cooler, and makes available a high-quality metal strip having uniform mechanical properties in the width direction thereof, through achievement of a uniform temperature distribution of the metal strip in the width direction thereof, thus providing industrially useful effect.
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Abstract
Description
- As far as we know, there are available the following prior art documents pertinent to the present invention:
- (1) Japanese Patent Publication No. 57-14,414 dated March 24, 1982; and
- (2) Japanese Patent Provisional Publication No. 2-274,822 dated November 9, 1990.
- The contents of the prior arts disclosed in the above-mentioned prior art documents will be discussed hereafter under the heading of the "BACKGROUND OF THE INVENTION".
- The present invention relates to an apparatus for continuously cooling a metal strip, which is continuously travelling in the longitudinal direction thereof, so as to achieve a uniform temperature distribution in the width direction of the metal strip.
- For example, continuous annealing of a metal strip is carried out as follows: A metal strip continuously travelling in the longitudinal direction thereof is continuously heated to a prescribed temperature and soaked. Then, the metal strip thus heated and soaked, which is continuously travelling in the longitudinal direction threreof, is continuously cooled to a prescribed temperature at a prescribed cooling rate immediately or after slowly cooling to a prescribed temperature. Then, the metal strip thus cooled is continuously subjected to an overaging treatment or a tempering treatment.
- For the purpose of cooling the metal strip in the above-mentioned continuous annealing treatment, the known methods include a water cooling, a gas cooling and a roll cooling. Among these cooling methods, the roll cooling has an advantage of permitting rapid cooling of the metal strip to any temperature. In this respect, the roll cooling is superior to the water cooling and the gas cooling.
- As an apparatus for continuously cooling a metal strip by the roll cooling, for example, Japanese Patent Publication No. 57-14,414 dated March 24, 1982 discloses an apparatus for continuously cooling a metal strip, which comprises:
a plurality of cooling rolls, which are freely rotatable and in contact with a metal strip continuously travelling in the longitudinal direction thereof, for continuously cooling said metal strip, each of said plurality of cooling rolls having a length at least equal to the width of said metal strip, said plurality of cooling rolls having respective axes in parallel with each other, a cooling liquid flowing through the interior of each of said plurality of cooling rolls to continuously cool same, and at least one of said plurality of cooling rolls is displaceable toward said metal strip to control a contact area between the surface of said cooling roll and the surface of said metal strip (hereinafter referred to as the "prior art 1"). - Fig. 35 is a descriptive view illustrating a typical apparatus for continuously cooling a metal strip, for example, a steel strip according to the above-mentioned
prior art 1. As shown in Fig. 35, a plurality ofcooling rolls 2 comprising, for example, fiverolls 2a to 2e, which are freely rotatable and in contact with asteel strip 1 continuously travelling in the longitudinal direction thereof, for continuously cooling the steel strip, are arranged with the axes thereof in parallel with each other, at prescribed intervals. - Each of the
cooling rolls 2 has a length at least equal to the width of thesteel strip 1, and a cooling liquid flows through the interior of thecooling roll 2 to continuously cool same. Each of thecooling rolls 2 is displaceable toward thesteel strip 1 by a driving mechanism not shown, to control the contact area between the surface of thecooling roll 2 and the surface of thesteel strip 1. - The
steel strip 1 continuously travels in the direction as shown by the arrow in Fig. 35, while coming into contact with each of the above-mentioned plurality ofcooling rolls 2. In the meantime, the portion of the surface of thesteel strip 1 in contact with the surface of each of thecooling rolls 2 is cooled. The contact area between the surface of thesteel strip 1 and the surface of each of thecooling rolls 2 is controlled by causing each of thecooling rolls 2 to displace toward thesteel strip 1. Thesteel strip 1 is thus continuously cooled to a prescribed temperature by the plurality ofcooling rolls 2. - The above-mentioned
prior art 1 has the following problems: In order to continuously cool thesteel strip 1 continuously travelling in the longitudinal direction thereof so as to achieve a uniform temperature distribution in the width direction thereof, it is necessary to bring the surface of thesteel strip 1 and the surface of each of the plurality ofcooling rolls 2 into close contact with each other uniformly in the width direction of thesteel strip 1. - However, it is difficult to bring the surface of the
steel strip 1 and the surface of thecooling rolls 2 into close contact with each other uniformly in the width direction of thesteel strip 1 for the following reasons: - (1) The
steel strip 1, when coming into contact with each of the plurality ofcooling rolls 2, is bent into an arcuate shape by each of the plurality ofcooling rolls 2, thus resulting in a saddle-shaped deformation of thesteel strip 1 in the width direction thereof. - (2) Fluctuations of thickness in the width direction, a defective shape and non-uniform tension in the width direction exist in the
steel strip 1. - (3) The contact with the high-
temperature steel strip 1 causes occurrence of a roll crown resulting from the thermal deformation in each of the plurality ofcooling rolls 2. - (4) The plurality of
cooling rolls 2 are non-uniform in the surface roughness. - It therefore becomes particularly difficult for the surfaces of the both side edge portions of the
steel strip 1 in the width direction thereof to be in contact with the surface of each of the plurality ofcooling rolls 2. - Fig. 36 is a graph illustrating a temperature distribution of a
steel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 under, for example, the following conditions by means of the cooling apparatus according to theprior art 1 as shown in Fig. 35: - (1) Thickness of the steel strip 1: 1.2 mm,
- (2) Width of the steel strip 1: 1,200 mm,
- (3) Cooling start temperature of the steel strip 1 : about 600°C,
- (4) Target temperature for cooling of the steel strip 1 : 350°C,
- (5) Chemical composition of the steel strip 1 : as shown in Table 1,
- In Fig. 36, the abscissa represents a distance from the side edge of the
steel strip 1 toward the center in the width direction thereof, and the ordinate represents a temperature of thesteel strip 1 in the width direction thereof. - As shown in Fig. 36, the temperature of the
steel strip 1 in the width direction thereof on the exit side of thecooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 100 mm from the side edge of thesteel strip 1, and is about 570°C at a position, for example, of 20 mm from the side edge of thesteel strip 1, and about 350°C at a position of 100 mm from the side edge thereof. Thus, the temperature distribution in the width direction of thesteel strip 1 on the exit side of thecooling roll 2e is non-uniform with a higher temperature on the side edge than at the center, the difference in temperature being approximately 220°C between the center and the side edge. This causes occurrence of a defective shape such as edge waves or heat buckles in thesteel strip 1 after the roll cooling. - When the edge waves exist in the side edges of the
steel strip 1, an abnormal travelling such as a zigzag motion occurs in thesteel strip 1 continuously travelling in the longitudinal direction thereof in the next treatment process such as an overaging treatment process applied to thesteel strip 1 after the roll cooling. In an extreme case, as a result, thesteel strip 1 is broken, thus making it impossible to continue the operation. It therefore becomes necessary to reduce the travelling speed of thesteel strip 1 after the roll cooling in the next treatment process, and this seriously impairs the operational efficiency. When the heat buckles are present in thesteel strip 1, the steel strip is rejected as a defective product, thus reducing the product yield. - Fig. 37 is a graph illustrating an aging index (AI) of the above-mentioned
steel strip 1 in the width direction thereof, when thesteel strip 1 is subjected to an overaging treatment at a temperature of 350°C for two minutes, then to a temper rolling with a reduction ratio of 1.5%, and then, to an aging treatment at a temperature of 100°C for 60 minutes. In Fig. 37, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of thesteel strip 1 in the width direction thereof. - The higher yield point of the
steel strip 1 resulting from the aging causes occurrence of a defective shape and a spring-back during the press-forming and deterioration of a yield point elongation and a buckling resistance of thesteel strip 1. The extent of the occurrence of these defects differs in the width direction of thesteel strip 1. - In the
steel strip 1 having the above-mentioned dimensions and chemical composition, if the upper limit of the aging index (AI) up to which a yield point elongation does not occur during the press-forming, is assumed to be, for example, 4 kgf/mm², then, as is clear from Fig. 37, the portion from the side edge to about 90 mm of thesteel strip 1 would have a high aging index of over 4 kgf/mm². This leads to non-uniform mechanical properties of thesteel strip 1 in the width direction thereof. - As an apparatus for continuously cooling a steel strip by the roll cooling to solve the above-mentioned problems, Japanese Patent Provisional Publication No. 2-274,822 dated November 9, 1990 discloses an apparatus for continuously cooling a steel strip, which comprises:
a plurality of cooling rolls, which are freely rotatable and in contact with a steel strip continuously travelling in the longitudinal direction thereof, for continuously cooling said steel strip, each of said plurality of cooling rolls having a length at least equal to the width of said steel strip, said plurality of cooling rolls having respective axes in parallel with each other, a cooling liquid flowing through the interior of each of said cooling rolls to continuously cool same; and
a gas cooler, arranged on the exit side of said plurality of cooling rolls, for continuously cooling said steel strip by blowing a cooling gas onto the surface of said steel strip so as to achieve a uniform temperature distribution in the width direction of said steel strip after the final cooling thereof, said gas cooler being arranged in the width direction of said steel strip at a prescribed distance from each of the both surfaces of said steel strip, said gas cooler comprising a plurality of mutually independent nozzle headers for blowing said cooling gas onto the surface of said steel strip, and said plurality of nozzle headers controlling at least one of a flow rate and a flow velocity of said cooling gas in the width direction of said steel strip (hereinafter referred to as the "prior art 2"). - Fig. 38 is a descriptive view illustrating a typical apparatus for continuously cooling a steel strip according to the above-mentioned
prior art 2. As shown in Fig. 38, there are arranged a plurality ofcooling rolls 2 of the same construction as those described in theprior art 1, for continuously cooling asteel strip 1 continuously travelling in the longitudinal direction thereof. Agas cooler 3 is arranged on the exit side of the plurality of cooling rolls in the width direction of thesteel strip 1 continuously travelling in the longitudinal direction thereof, at a prescribed distance from each of the both surfaces of thesteel strip 1. Fig. 39 is a schematic perspective view illustrating - a
typical gas cooler 3 used in the apparatus according to theprior art 2. As shown in Fig. 39, thegas cooler 3 comprises a plurality of mutuallyindependent nozzle headers 4 for blowing a cooling gas onto the surface of thesteel strip 1. The plurality ofnozzle headers 4 control at least one of the flow rate and the flow velocity of the cooling gas in the width direction of thesteel strip 1. Each of the plurality ofnozzle headers 4 has a plurality ofnozzles 5 provided at prescribed intervals in the longitudinal direction of thenozzle header 4. - In Fig. 39, 6 is a duct for supplying a cooling gas from a cooling gas reservoir not shown to each of the
nozzle headers 4. Each of a plurality ofbranch pipes 7 branching from theduct 6 is connected to each of the plurality ofheaders 4. Ablower 8 and acooler 9 for cooling the cooling gas flowing through theduct 6 are provided in the middle of theduct 6, and acontrol valve 10 is provided in the middle of each of thebranch pipes 7. - The
steel strip 1 continuously travels in the direction as shown by the arrow in Fig. 38 while coming into contact with each of the above-mentioned plurality of cooling rolls 2. In the meantime, the portion of the surface of thesteel strip 1 coming into contact with the surface of each of the cooling rolls 2 is cooled. - The
steel strip 1 cooled by each of the plurality of cooling rolls 2 to a prescribed temperature is then introduced into thegas cooler 3, in which the cooling gas is blown from each of the plurality ofnozzle headers 4 so as to achieve a uniform temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof. At least one of the flow rate and the flow velocity of the cooling gas is controlled by means of thecontrol valve 10 provided in the middle of each of the plurality ofbranch pipes 7. - Fig. 40 is a graph illustrating a temperature distribution of the
same steel strip 1 as that of theprior art 1 in the width direction thereof, when continuously cooling thesteel strip 1 from the cooling start temperature of about 600°C to the target temperature for cooling of 350°C by means of the apparatus according to theprior art 2 as shown in Fig. 38. In Fig. 40, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents a temperature of thesteel strip 1 in the width direction thereof. Also in Fig. 40, the solid line represents the temperature of thesteel strip 1 on the exit side of each of fivecooling rolls 2a to 2e, and the dotted line represents a temperature of thesteel strip 1 in the width direction thereof. - As shown by the solid line in Fig. 40, the temperature of the
steel strip 1 in the width direction thereof on the exit side of thecooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 100 mm from the side edge of thesteel strip 1, and is about 570°C at a position, for example, of 20 mm from the side edge of thesteel strip 1. On the exit side of thegas cooler 3, however, thesteel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edge to the center of thesteel strip 1, as shown by the dotted line in Fig. 40. - Fig. 41 is a graph illustrating an aging index (AI) of the above-mentioned
steel strip 1. In Fig. 41, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of thesteel strip 1 in the width direction thereof. As is clear from Fig. 41, the portion showing an aging index of over 4 kgf/mm² covers about 80 mm from a side edge of thesteel strip 1. - The above-mentioned
prior art 2 has the following problems: - (1) The
steel strip 1 continuously travelling through the plurality of cooling rolls 2 has a low tension. As a result, the both side edges of thesteel strip 1 in the width direction thereof forms an upward warp from the surface of each of the plurality of cooling rolls 2, with a large width and a large height of such a warp. The both side edges of thesteel strip 1 in the width direction thereof has therefore a higher temperature than that of the center portion thereof on the exit side of the plurality of cooling rolls 2.
It is therefore necessary to increase the time and the quantity of blowing of the cooling gas onto the surface of thesteel strip 1 by means of thegas cooler 3, thus requiring a larger-scale gas cooler 3, resulting in higher installation and running costs. - (2) The
steel strip 1 continuously travelling through thegas cooler 3 has a low tension. This causes a vibration or a zigzag motion of thesteel strip 1 continuously travelling through thegas cooler 3. As a result, the contact of thesteel strip 1 with thegas cooler 3 causes occurrence of scratches in thesteel strip 1. When a clearance between thesteel strip 1 and thegas cooler 3 is increased so as to prevent contact between thegas cooler 3 and thesteel strip 1, a cooling effect of thesteel strip 1 by thegas cooler 3 decreases. - (3) Uniformity of an aging index (AI) of the
steel strip 1 in the width direction thereof is not sufficient. - Under such circumstances, when continuously cooling a metal strip continuously travelling in the longitudinal direction thereof by means of at least one cooling roll and a gas cooler, there is a strong demand for the development of an apparatus for continuously cooling a metal strip, which permits prevention of the occurrence of a defect such as edge waves, heat buckles or scratches in the metal strip and an abnormal travelling of the metal strip such as a zigzag motion in the next process, requires only limited installation and running costs of the gas cooler, and makes available a high-quality metal strip having uniform mechanical properties in the width direction thereof, through achievement of a uniform temperature distribution of the metal strip in the width direction thereof, but such an apparatus has not as yet been proposed.
- An object of the present invention is therefore to provide, when continuously cooling a metal strip continuously travelling in the longitudinal direction thereof by means of at least one cooling roll and a gas cooler, an apparatus for continuously cooling a metal strip, which permits prevention of the occurrence of a defect such as edge waves, heat buckles or scratches in the metal strip and an abnormal travelling of the metal strip such as a zigzag motion in the next process, requires only limited installation and running costs of the gas cooler, and makes available a high-quality metal strip having uniform mechanical properties in the width direction thereof, through achievement of a uniform temperature distribution of the metal strip in the width direction thereof.
- In accordance with one of the features of the present invention, there is provided, in an apparatus for continuously cooling a metal strip, which comprises:
at least one cooling roll, which is freely rotatable and in contact with a metal strip continuously travelling in the longitudinal direction thereof, for continuously cooling said metal strip, said cooling roll having a length at least equal to the width of said metal strip, a cooling liquid flowing through the interior of said cooling roll to continuously cool same, and a contact area between the surface of said cooling roll and the surface of said metal strip being controllable; and
a gas cooler, arranged on the exit side of said at least one cooling roll, for continuously cooling said metal strip by blowing a cooling gas onto the surface of said metal strip so as to achieve a uniform temperature distribution in the width direction of said metal strip after the final cooling thereof, said gas cooler being arranged in the width direction of said metal strip at a prescribed distance from each of the both surfaces of said metal strip, said gas cooler comprising a plurality of mutually independent nozzle headers for blowing said cooling gas onto the surface of said metal strip, and said plurality of nozzle headers controlling at least one of a flow rate and a flow velocity of said cooling gas in the width direction of said metal strip;
there is provided the improvement
a first tension regulator comprising at least two rolls is arranged on the entry side of said plurality of cooling rolls, and a second tension regulator comprising at least two rolls is arranged on the exit side of said gas cooler. -
- Fig. 1 is a descriptive view illustrating a first embodiment of the apparatus of the present invention;
- Fig. 2 is a flow diagram illustrating a typical cooling system using the apparatus of the first embodiment of the present invention;
- Fig. 3 is a schematic perspective view illustrating a typical gas cooler used in the apparatus of the present invention;
- Fig. 4 is a graph illustrating the relationship between a tension of a steel strip travelling through a cooling roll and a height of an upward warp of the steel strip at the side edge portion in the width direction thereof from the surface of the cooling roll;
- Fig. 5 is a graph illustrating the relationship between a tension of a steel strip travelling through a gas cooler and a rate of occurrence of scratches on the steel strip;
- Fig. 6 is a graph illustrating an amount of temperature drop of a steel strip for each of a plurality of cooling rolls, when continuously cooling the steel strip by means of the apparatus of the first embodiment of the present invention;
- Fig. 7 is a graph illustrating a temperature distribution of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the first embodiment of the present invention;
- Fig. 8 is a graph illustrating an aging index (AI) of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the first embodiment of the present invention;
- Fig. 9 is a schematic side view illustrating a typical apparatus of the first embodiment of the present invention;
- Fig. 10 is a graph illustrating the relationship between a hydrogen gas content in a cooling gas used in the apparatus of the present invention and an amount of heat transfer per unit time of the cooling gas;
- Fig. 11 is a descriptive view illustrating a second embodiment of the apparatus of the present invention;
- Fig. 12 is a graph illustrating a temperature distribution of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the second embodiment of the present invention;
- Fig. 13 is a graph illustrating an aging index (AI) of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the second embodiment of the present invention;
- Fig. 14 is a descriptive view illustrating a third embodiment of the apparatus of the present invention;
- Fig. 15 is a graph illustrating a temperature distribution of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the third embodiment of the present invention;
- Fig. 16 is a graph illustrating an aging index (AI) of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the third embodiment of the present invention;
- Fig. 17 is a descriptive view illustrating a fourth embodiment of the apparatus of the present invention;
- Fig. 18 is a graph illustrating a temperature distribution of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the fourth embodiment of the present invention;
- Fig. 19 is a graph illustrating an aging index (AI) of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the fourth embodiment of the present invention;
- Fig. 20 is a descriptive view illustrating a fifth embodiment of the apparatus of the present invention;
- Fig. 21 is a schematic front view illustrating a typical cooling roll used in the apparatus of the fifth embodiment;
- Fig. 22 is a graph illustrating a temperature distribution of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the fifth embodiment of the present invention;
- Fig. 23 is a graph illustrating an aging index (AI) of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the fifth embodiment of the present invention;
- Fig. 24 is a descriptive view illustrating the sixth embodiment of the apparatus of the present invention;
- Fig. 25 is a schematic side view illustrating a typical apparatus of the sixth embodiment of the present invention;
- Fig. 26 is a descriptive view illustrating the functions of a thermometer used in the apparatus of the sixth embodiment;
- Fig. 27 is a graph illustrating a temperature distribution of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the sixth embodiment of the present invention;
- Fig. 28 is a graph illustrating an aging index (AI) of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the sixth embodiment of the present invention;
- Fig. 29 is a descriptive view illustrating a seventh embodiment of the apparatus of the present invention;
- Fig. 30 is a descriptive view illustrating an eighth embodiment of the apparatus of the present invention;
- Fig. 31 is a graph illustrating a temperature distribution of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the eighth embodiment of the present invention;
- Fig. 32 is a graph illustrating an aging index (AI) of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus of the eighth embodiment of the present invention;
- Figs. 33(A) and 33(B) are flow diagrams illustrating a typical continuous annealing equipment incorporating the apparatus of the first embodiment;
- Figs. 34(A), 34(B) and 34(C) are schematic flow diagrams each illustrating a typical chemical pretreatment zone in the continuous annealing equipment;
- Fig. 35 is a descriptive view illustrating a typical apparatus for continuously cooling a metal strip, for example, a steel strip according to the
prior art 1; - Fig. 36 is a graph illustrating a temperature distribution of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus according to the
prior art 1; - Fig. 37 is a graph illustrating an aging index (AI) of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus according to the
prior art 1; - Fig. 38 is a descriptive view illustrating a typical apparatus for cooling a steel strip according to the
prior art 2; - Fig. 39 is a schematic perspective view illustrating a typical gas cooler used in the apparatus according to the
prior art 2; - Fig. 40 is a graph illustrating a temperature distribution of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus according to the
prior art 2; and - Fig. 41 is a graph illustrating an aging index (AI) of a steel strip in the width direction thereof, when continuously cooling the steel strip by means of the apparatus according to the
prior art 2. - From the above-mentioned point of view, extensive studies were carried out to develop an apparatus for continuously cooling a metal strip, which permits, when continuously cooling the metal strip continuously travelling in the longitudinal direction thereof by means of at least one cooling roll and a gas cooler, prevention of the occurrence of a defect such as edge waves, heat buckles or scratches in the metal strip and an abnormal traveling of the metal strip such as a zigzag motion in the next process, requires only limited installation and running costs of the gas cooler, and makes available a high-quality metal strip having uniform mechanical properties in the width direction thereof, through achievement of a uniform temperature distribution of the metal strip in the width direction thereof.
- As a result, the following findings were obtained: It is possible to prevent the occurrence of a defect such as edge waves, heat buckles or scratches, and an abnormal travelling of the metal strip such as a zigzag motion in the next process, to save the installation and running costs of the gas cooler, and to obtain a high-quality metal strip having uniform mechanical properties in the width direction thereof, by arranging a first tension regulator comprising at least two rolls on the entry side of the above-mentioned at least one cooling roll for continuously cooling a metal strip travelling in the longitudinal direction thereof, and by arranging a second tension regulator comprising at least two rolls on the exit side of the above-mentioned gas cooler for continuously cooling the metal strip by blowing a cooling gas.
- The present invention was made on the basis of the above-mentioned findings. The apparatus of the present invention is described below with reference to the drawings as to the continuous cooling of a steel strip.
- Fig. 1 is a descriptive view illustrating a first embodiment of the apparatus of the present invention. As shown in Fig. 1, the apparatus of the first embodiment comprises a plurality of cooling rolls 2, which are freely rotatable and in contact with a
steel strip 1 continuously travelling in the longitudinal direction thereof, for continuously cooling thesteel strip 1, agas cooler 3, arranged on the exit side of the plurality of cooling rolls 2, for continuously cooling thesteel strip 1 by blowing a cooling gas onto the surface of thesteel strip 1 so as to achieve a uniform temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof, afirst tension regulator 17, comprising at least two bridle rolls, arranged on the entry side of the plurality of cooling rolls 2, and asecond tension regulator 18, comprising at least two bridle rolls, arranged on the exit side of thegas cooler 3. Also in Fig. 1, 19 are deflector rolls, each installed on each of the entry side and the exit side of thegas cooler 3, for keeping a clearance of thesteel strip 1 travelling through thegas cooler 3 from thegas cooler 3. - The plurality of cooling rolls 2 are arranged with the axes thereof in parallel with each other at prescribed intervals. Each of the plurality of cooling rolls 2 has a length at least equal to the width of the
steel strip 1. A cooling liquid flows through the interior of each of the cooling rolls 2 to continuously cool same. Each of the plurality of cooling rolls 2 is displaceable toward thesteel strip 1 by a driving mechanism not shown to control the contact area between the surface of each of the cooling rolls 2 and the surface of thesteel strip 1. - The
gas cooler 3 is arranged in the width direction of thesteel strip 1 at a prescribed distance from each of the both surfaces of thesteel strip 1 continuously travelling in the longitudinal direction thereof. Thegas cooler 3 shown in Fig. 39 according to theprior art 2 may be used also in the apparatus of the present invention. As shown in Fig. 39, thegas cooler 3 comprises a plurality of mutuallyindependent nozzle headers 4 for blowing a cooling gas onto the surface of thesteel strip 1. The plurality ofnozzle headers 4 control at least one of the flow rate and the flow velocity of the cooling gas in the width direction of the steel strip. - Each of the plurality of
nozzle headers 4 has a plurality ofnozzles 5 provided at prescribed intervals in the longitudinal direction of thenozzle header 4. Thenozzle 5, which is hole-shaped in 39, may be slit-shaped. In Fig. 39, 6 is a duct for supplying a cooling gas from a cooling gas reservoir not shown to each of thenozzle headers 4. Each of a plurality ofbranch pipes 7 branching from theduct 6 is connected to each of the plurality ofheaders 4. Ablower 8 and acooler 9 for cooling the cooling gas flowing through theduct 6 are provided in the middle of theduct 6, and acontrol valve 10 is provided in the middle of each of thebranch pipes 7. - Fig. 2 is a flow diagram illustrating a typical cooling system using the apparatus of the first embodiment of the present invention. As shown in Fig. 2, a
thermometer 11 for continuously measuring a temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof, is provided on the exit side of thegas cooler 3. Target temperature in the width direction of thesteel strip 1 after the final cooling thereof, are stored in acomputer 12. - The
thermometer 11 continuously measures the temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof, and transmits the result of measurement to afirst comparator 13. Thefirst comparator 13 compares the result of measurement transmitted from thethermometer 11 with the target temperature in the width direction of thesteel strip 1 after the final cooling thereof transmitted from thecomputer 12, and calculates the difference therebetween. - The
first comparator 12 transmits a signal for controlling at least one of a flow rate and a flow velocity of the cooling gas in the width direction of thesteel strip 1 to thecontrol valve 10 provided in the middle of each of the plurality ofbranch pipes 7 so that the difference as calculated above becomes null. At least one of the flow rate and the flow velocity of the cooling gas blown from each of the plurality ofnozzle headers 4 of thegas cooler 3 onto the surface of thesteel strip 1 is thus controlled in the width direction of thesteel strip 1 so as to achieve a uniform temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof. - The
computer 12 stores also cooling conditions by thegas cooler 3 for each of a thickness, a heat treatment cycle (including a cooling start temperature, a cooling rate and a target temperature for cooling) and a travelling speed of thesteel strip 1. When there is a change in any of the thickness, the heat treatment cycle and the travelling speed of thesteel strip 1, achange commander 14 transmits a change signal of the cooling conditions to asecond comparator 15 based on a signal from thecomputer 12. Aseam position detector 16 detects, on the other hand, a seam position of thesteel strip 1, for which the thickness or the travelling speed has been changed, and transmits a detection signal to thesecond comparator 15. On the basis of the detection signal from theseam position detector 16, thesecond comparator 15 transmits a signal to theblower 8 and thecooler 9 to control at least one of the flow rate and the flow velocity of the cooling gas blown by theblower 8 and the cooling conditions of the cooling gas by thecooler 9. This regulates the amount of cooling of thesteel strip 1 by thegas cooler 3. - Fig. 3 is a schematic perspective view illustrating another typical gas cooler used in the apparatus of the present invention. As shown in Fig. 3, the
gas cooler 3 may comprise, for example, threenozzle headers steel strip 1. When thegas cooler 3 has such a construction, it is possible to cope with a change in the width of thesteel strip 1 or a zigzag motion of thesteel strip 1. - In the apparatus of the first embodiment, as described above, the
first tension regulator 17 is arranged on the entry side of the plurality of cooling rolls 2, and thesecond tension regulator 18 is arranged on the exit side of thegas cooler 3. A desired tension is therefore imparted to thesteel strip 1 continuously travelling through the plurality of cooling rolls 2 and thegas cooler 3. This reduces the occurrences of a defective contact between the surface of thesteel strip 1 and the surface of each of the plurality of cooling rolls 2, and the occurrences of scratches in thesteel strip 1 caused by the contact with thegas cooler 3 during travelling through thegas cooler 3. - Fig. 4 is a graph illustrating the relationship between a tension of the
steel strip 1 continuously travelling while coming into contact with each of the plurality of cooling rolls 2 and a height of an upward warp of thesteel strip 1 at the side edge portion in the width direction thereof from the surface of each of the cooling rolls 2. In Fig. 4, the abscissa represents a tension acting on thesteel strip 1, and the ordinate represents a height of an upward warp of thesteel strip 1 at the side edge portion thereof from the surface of thecooling roll 1. As is clear from Fig. 4, when a tension of thesteel strip 1 continuously travelling while coming into contact with each of the plurality of cooling rolls 2 is increased, for example, to at least 3 kg/mm² by means of thefirst tension regulator 17 and thesecond tension regulator 18, the height of the upward warp at the side edge portion of thesteel strip 1 from the surface of each of thecooling rollers 2 decreases to up to 10 mm. - As a result, the difference in temperature between the both side edges of the
steel strip 1 in the width direction thereof and the center portion of thesteel strip 1 on the exit side of the plurality of cooling rolls 2 is reduced. This permits saving of the blowing time of the cooling gas and the quantity of the blown cooling gas onto the surface of thesteel strip 1 by thegas cooler 3 for achieving a uniform temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof. The installation and running costs of thegas cooler 3 are largely reduced as compared with the apparatus of theprior art 2. - Fig. 5 is a graph illustrating the relationship between a tension of the
steel strip 1 continuously travelling through thegas cooler 3 and a rate of occurrence of scratches on thesteel strip 1 caused by the contact of thesteel strip 1 with thegas cooler 3. In Fig. 5, the abscissa represents acting on thesteel strip 1, and the ordinate represents a rate of occurrence of scratches on thesteel strip 1. Also in Fig. 5, the curve "a" represents the rate of occurrence of scratches with a clearance of 75 mm between thesteel strip 1 and thegas cooler 3, and the curve "b" represents the rate of occurrence of scratches with a clearance of 150 mm between thesteel strip 1 and thegas cooler 3. - As is clear from Fig. 5, the rate of occurrence of scratches on the
steel strip 1 is decreased according as the tension of thesteel strip 1 continuously travelling is increased. When the tension of thesteel strip 1 is increased to at least 3 kg/mm², almost no scratches are caused on thesteel strip 1 even if the clearance between thesteel strip 1 and thegas cooler 3 is reduced to 75 mm. It is thus possible to reduce the clearance between thesteel strip 1 and thegas cooler 3 without causing scratches on thesteel strip 1 by increasing the tension of thesteel strip 1 continuously travelling through thegas cooler 3, thus improving the cooling effect by thegas cooler 3. - As shown in Fig. 1, the contact area between the surface of the
steel strip 1 and the surface of each of the first-half cooling rolls 2a, 2b and 2c from among the plurality of cooling rolls 2 should preferably be larger than the contact area between the surface of thesteel strip 1 and the surface of each of the latter-half cooling rolls 2d and 2e from among the plurality of cooling rolls 2. The contact area between the surface of thesteel strip 1 and the surface of each of the plurality of cooling rolls 2 can be controlled by causing each of the plurality of cooling rolls 2 to displace toward thesteel strip 1. - Fig. 6 is a graph illustrating an amount of temperature drop of the
steel strip 1 at each of the plurality ofcooling rolls steel strip 1 by means of the apparatus of the first embodiment of the present invention as shown in Fig. 1. As shown in Fig. 6, a larger contact area between the surface of-thesteel strip 1 and the surface of each of the first-half cooling rolls 2a, 2b and 2c results in a larger amount of temperature drop (ΔT) of thesteel strip 1 at each of the first-half cooling rolls 2a, 2b and 2c. This reduces the degree of unevenness of the temperature distribution of thesteel strip 1 in the width direction thereof on the exit side of thecooling roll 2e. - The reason is as follows: Upon contact of the
steel strip 1 with each of the pluraliry of cooling rolls 2, a saddle-shaped deformation occurs in thesteel strip 1 in the width direction thereof, as described before. Such a saddle-shaped deformation occurs, for thefirst cooling roll 2a, within very limited portions of the both side edge of thesteel strip 1. However, when thesteel strip 1 sequentially comes into contact with each of the cooling rolls 2b to 2e, the range of occurrence of the saddle-shaped deformation expands in the width direction of thesteel strip 1. The both side edge portions of thesteel strip 1 in the width direction thereof on the exit side of thefinal cooling roll 2e therefore form an upward warp largely apart from the surface of the final cooling rolls 2e, and thus, the both side edge portions of thesteel strip 1 have a higher temperature than that of the center portion thereof. - Therefore, it is possible to inhibit the increase of deformations in the width direction of the
steel strip 1 and thus to prevent propagation of the above-mentioned upward warp to the center portion of thesteel strip 1 by increasing the contact area between the surface of thesteel strip 1 and the surface of each of the first-half cooling rolls 2a, 2b and 2c, which have a relatively limited range of occurrence of the saddle-shaped deformations, and increasing the amount of temperature drop of thesteel strip 1 at the first-half cooling rolls 2a, 2b and 2c. - This reduces the non-uniformity of the temperature distribution of the
steel strip 1 in the width direction thereof on the exit side of thecooling roll 2e. Alternatively, the contact area between the surface of thesteel strip 1 and the surface of each of the plurality ofcooling rolls downstream cooling roll 2e toward theupstream cooling roll 2a. - Fig. 7 is a graph illustrating a temperature distribution of a
steel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 under the same conditions as in theprior art 2 by means of the apparatus of the first embodiment of the present invention as shown in Fig. 1. In Fig. 7, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof and the ordinate represents a temperature of thesteel strip 1 in the width direction thereof. As shown by the solid line in Fig. 7, the temperature of thesteel strip 1 in the width direction thereof on the exit side of thecooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 50 mm from the side edge of thesteel strip 1, and is about 480°C at a position, for example, of 20 mm from the side edge of thesteel strip 1. On the exit side of thegas cooler 3, however, thesteel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edged to the center of thesteel strip 1, as shown by the dotted line in Fig. 7. - The one-point chain line in Fig. 7 represents a temperature distribution of a
steel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 by means of the above-mentionedprior art 1, i.e., by means of the plurality of cooling rolls 2 alone. The two-point chain line in Fig. 7 represents a temperature distribution of asteel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 by means of the plurality of cooling rolls 2 alone, with however two tension regulators each provided on the entry side and the exit side of the plurality of cooling rolls 2. As is clear from Fig. 7, cooling of thesteel strip 1 by means of the apparatus of the first embodiment of the present invention permits achievement of a uniform temperature distribution of thesteel strip 1 in the width direction thereof as compared with theprior art 1. - Fig. 8 is a graph illustrating an aging index (AI) of the above-mentioned
steel strip 1 in the width direction thereof. In Fig. 8, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof and the ordinate represents an aging index (AI) of thesteel strip 1 in the width direction thereof. As is evident from Fig. 8, the portion showing an aging index of over 4 kgf/mm² covers only about 30 mm from the side edge of thesteel strip 1, thus the portion having an aging index of over 4 kgf/mm² is remarkably reduced as compared with theprior arts - The one-point chain line in Fig. 8 represents an aging index of a
steel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 by means of the above-mentionedprior art 1, i.e., by means of the plurality of cooling rolls 2 alone. The two-point chain line in Fig. 8 represents an aging index of asteel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 by means of the plurality of cooling rolls 2 alone, with however two tension regulators each provided on the entry side and the exit side of the plurality of cooling rolls 2. - As is clear from Fig. 8, cooling of the
steel strip 1 by means of the apparatus of the first embodiment of the present invention permits achievement of a uniform aging index of thesteel strip 1 in the width direction thereof as compared with theprior art 1. As is clear from the comparison with the graph shown in Fig. 41, furthermore, when cooling thesteel strip 1 by means of the apparatus of the first embodiment of the present invention, the aging index of thesteel strip 1 in the width direction thereof becomes uniform even as compared with theprior art 2. - Fig. 9 is a schematic side view illustrating a typical apparatus of the first embodiment of the present invention. As shown in Fig. 9, the
first tension regulator 17 comprising at least two bridle rolls is arranged on the entry side of the plurality of cooling rolls 2, and thesecond tension regulator 18 comprising at least two bridle rolls is arranged on the exit side of thegas cooler 3. Athermometer 11 for continuously measuring a temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof is provided on the exit side of thegas cooler 3. Thedeflector roll 19 is provided on each of the entry side and the exit side of thegas cooler 3. - In Fig. 9, 20 is a blower, driven by a
motor 21, for blowing a cooling gas through a duct 23 into thegas cooler blower 20, the cooler 22, the duct 23 and thegas cooler 3 are housed in agas cooling chamber 24 shield from the open air.Slots 26 and 26' for passing thesteel strip 1 are provided on each of the entry side and the exit side of thegas cooling chamber 24. A dumper not shown is provided in the middle of the duct 23, for controlling in the width direction of thesteel strip 1 at least one of the flow rate and the flow velocity of the cooling gas in the width direction of thesteel strip 1. - As shown in Fig. 9, the
steel strip 1 continuously travelling in the longitudinal direction thereof, which has been slowly cooled to a prescribed temperature in apreliminary cooling zone 25, is introduced through thefirst tension regulator 17 to the plurality of cooling rolls 2. Thesteel strip 1 is then cooled by the contact with each of the plurality of cooling rolls 2. Then, thesteel strip 1 is introduced through aslot 26 into thegas cooling chamber 24. Thesteel strip 1 is cooled in thegas cooler 3 in thegas cooling chamber 24 so as to achieve a uniform temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof. Thesteel strip 1 cooled in thegas coller 3 leaves thegas cooling chamber 24 through another slot 26' and directed through thesecond tension regulator 18 to the next treatment process. - On the basis of the temperature distribution in the width direction of the
steel strip 1 after the final cooling thereof, as measured by thethermometer 11, at least one of the flow rate and the flow velocity of the cooling gas which is blown onto the surface of thesteel strip 1 is controlled by the dumper not shown, provided in the middle of the duct 23. - As the cooling gas, it is desirable to use a mixed gas, which comprises a hydrogen gas of from 40 to 90 vol.% and a nitrogen gas of from 10 to 60 vol.%, and has a large amount of heat transfer per unit time. Fig. 10 is a graph illustrating, in a cooling gas comprising a mixed gas of hydrogen gas and nitrogen gas, the relationship between a hydrogen gas content in the cooling gas and an amount of heat transfer per unit time of the cooling gas. As is clear from Fig. 10, a hydrogen gas content in the above-mentioned cooling gas of under 40 vol.% or over 90 vol.% leads to a decreased amount of heat transfer per unit time of the cooling gas. The most desirable hydrogen gas content in the cooling gas is about 70 vol.%.
- The hydrogen gas content in the cooling gas is adjusted when changing the thickness, the heat treatment cycle or the travelling speed of the
steel strip 1. As required, the hydrogen gas content in the cooling gas may be changed in the width direction of thesteel strip 1 so as to control the cooling conditions of thesteel strip 1 in the width direction thereof. Alternatively, a helium gas may be employed in place of a hydrogen gas. - Fig. 11 is a descriptive view illustrating a second embodiment of the apparatus of the present invention. As shown in Fig. 11, the apparatus of the second embodiment is identical with the apparatus of the first embodiment shown in Fig. 1, except that another gas cooler 27 for continuously cooling the
steel strip 1 by blowing a cooling gas onto the surface of thesteel strip 1 so as to achieve a uniform temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof, is arranged between thefirst tension regulator 17 and the plurality of cooling rolls 2. - Fig. 12 is a graph illustrating a temperature distribution of a
steel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 under the same conditions as in the first embodiment by means of the apparatus of the second embodiment of the present invention as shown in Fig. 11. In Fig. 12, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents a temperature of thesteel strip 1 in the width direction thereof. As shown by the solid line in Fig. 12, the temperature of thesteel strip 1 in the width direction thereof on the exit side of thecooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 50 mm from the side edge of thesteel strip 1. On the exit side of thegas cooler 3, however, thesteel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edge to the center of thesteel strip 1, as shown by the dotted line in Fig. 16. - Fig. 13 is a graph illustrating an aging index (AI) of the above-mentioned
steel strip 1 in the width direction thereof. In Fig. 13, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of thesteel strip 1 in the width direction thereof. As is clear from Fig. 13, the portion showing an aging index of over 4 kgf/mm² covers only about 30 mm from the side edge of thesteel strip 1, with a maximum aging index of 4.8 kgf/mm², thus the portion having an aging index of over 4 kgf/mm² is remarkably reduced as compared with theprior arts - Fig. 14 is a descriptive view illustrating a third embodiment of the apparatus of the present invention. As shown in Fig. 14, the apparatus of the third embodiment is identical with the apparatus of the first embodiment shown in Fig. 1, except that another gas cooler 28 for continuously cooling the
steel strip 1 by blowing a cooling gas onto the surface of thesteel strip 1 so as to achieve a uniform temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof, is arranged in the middle portion of the plurality of cooling rolls 2, i.e., between the first-half cooling rolls 2a, 2b and 2c and the latter-half cooling rolls 2d and 2e. - Fig. 15 is a graph illustrating a temperature distribution of a
steel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 under the same conditions as in the first embodiment by means of the apparatus of the third embodiment of the present invention as shown in Fig. 14. In Fig. 15, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents a temperature of thesteel strip 1 in the width direction thereof. As shown by the solid line in Fig. 15, the temperature of thesteel strip 1 in the width direction thereof on the exit side of thecooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 50 mm from the side edge of thesteel strip 1. On the exit side of thegas cooler 3, however, thesteel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edge to the center of thesteel strip 1, as shown by the dotted line in Fig. 15. The one-point chain line in Fig. 15 represents a temperature of thesteel strip 1 on the exit side of the anothergas cooler 28. - Fig. 16 is a graph illustrating an aging index (AI) of the above-mentioned
steel strip 1 in the width direction thereof. In Fig. 16, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of thesteel strip 1 in the width direction thereof. As is clear from Fig. 16, the portion showing an aging index of over 4 kgf/mm² covers only about 40 mm from the side edge of thesteel strip 1, with a maximum aging index of 4.8 kgf/mm², thus the portion having an aging index of over 4 kgf/mm² is remarkably reduced as compared with theprior arts - Fig. 17 is a descriptive view illustrating a fourth embodiment of the apparatus of the present invention. As shown in Fig. 17, the apparatus of the fourth embodiment is identical with the apparatus of the first embodiment shown in Fig. 1, except that another gas cooler 27 for continuously cooling the
steel strip 1 by blowing a cooling gas onto the surface of thesteel strip 1 so as to achieve a uniform temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof, is arranged between thefirst tension regulator 17 and the plurality of cooling rolls 2, and further another gas cooler 28 for continuously cooling thesteel strip 1 by blowing a cooling gas onto the surface of thesteel strip 1 so as to achieve a uniform temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof, is arranged in the middle portion of the plurality of cooling rolls 2, i.e., between the first-half cooling rolls 2a, 2b and 2c and the latter-half cooling rolls 2d and 2e. - Fig. 18 is a graph illustrating a temperature distribution of a
steel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 under the same conditions as in the first embodiment by means of the apparatus of the fourth embodiment of the present invention as shown in Fig. 17. In Fig. 18, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents a temperature of thesteel strip 1 in the width direction thereof. As shown by the solid line in Fig. 18, the temperature of thesteel strip 1 in the width direction thereof on the exit side of thecooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 50 mm from the side edge of thesteel strip 1. On the exit side of thegas cooler 3, however, thesteel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edge to the center of thesteel strip 1, as shown by the dotted line in Fig. 18. The one-point chain line in Fig. 18 represents a temperature of thesteel strip 1 on the exit side of the further anothergas cooler 28. - Fig. 19 is a graph illustrating an aging index (AI) of the above-mentioned
steel strip 1 in the width direction thereof. In Fig. 19, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of thesteel strip 1 in the width direction thereof. As is clear from Fig. 19, the portion showing an aging index of over 4 kgf/mm² covers only about 35 mm from the side edge of thesteel strip 1, with a maximum aging index of 4.8 kgf/mm², thus the portion having an aging index of over 4 kgf/mm² is remarkably reduced as compared with theprior arts - Fig. 20 is a descriptive view illustrating a fifth embodiment of the apparatus of the present invention. As shown in Fig. 20, the apparatus of the fifth embodiment is identical with the apparatus of the first embodiment shown in Fig. 1, except that a plurality of
gas blowing nozzles 29, which are directed toward a contact face between the surface of each of the plurality of cooling rolls 2 and the surface of thesteel strip 1, are provided on the side of the cooling rolls 2. - The plurality of
gas blowing nozzles 29 are provided stationarily or displaceably in the longitudinal direction of each of the cooling rolls 2, at prescribed intervals in the longitudinal direction of each of the cooling rolls 2. Each of the plurality ofgas blowing nozzles 29 continuously cools thesteel strip 1 by blowing a cooling gas onto the surface of thesteel strip 1 so as to achieve a uniform temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof. As shown in a schematic front view of Fig. 21,shallow grooves 30 for passing the blown cooling gas should preferably be provided on the surface of each of the plurality of cooling rolls 2 used in the apparatus of the fifth embodiment. - Fig. 22 is a graph illustrating a temperature distribution of a
steel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 under the same conditions as in the first embodiment by means of the apparatus of the fifth embodiment of the present invention as shown in Fig. 20. In Fig. 22, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents a temperature of thesteel strip 1 in the width direction thereof. As shown by the solid line in Fig. 22, the temperature of thesteel strip 1 in the width direction thereof on the exit side of thecooling roll 2e is over the target temperature for cooling of 350°C in a portion within about 55 mm from the side edge of thesteel strip 1. On the exit side of thegas cooler 3, however, thesteel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edge to the center of thesteel strip 1, as shown by the dotted line in Fig. 22. - Fig. 23 is a graph illustrating an aging index (AI) of the above-mentioned
steel strip 1 in the width direction thereof. In Fig. 23, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of thesteel strip 1 in the width direction thereof. As is clear from Fig. 23, the portion showing an aging index of over 4 kgf/mm² covers only about 35 mm from the side edge of thesteel strip 1, with a maximum aging index of 5.0 kgf/mm², thus the portion having an aging index of over 4 kgf/mm² is remarkably reduced as compared with theprior arts - Fig. 24 is a descriptive view illustrating a sixth embodiment of the apparatus of the present invention. As shown in Fig. 24, the apparatus of the sixth embodiment is identical with the apparatus of the first embodiment shown in Fig. 1, except that a plurality of
gas blowing nozzles 31, which are directed toward a contact face between the surface of each of the plurality of cooling rolls 2 and the surface of thesteel strip 1, are provided on the side of thesteel strip 1. - Fig. 25 is a schematic side view illustrating a typical apparatus of the sixth embodiment of the present invention. As shown in Fig. 25, each of the plurality of
gas blowing nozzles 31 comprises anarcuate nozzle header 32, provided on the side of thesteel strip 1 toward a contact face between the surface of each of the plurality of cooling rolls 2 and the surface of thesteel strip 1, and a plurality ofnozzles 33 provided at prescribed intervals on each of thearcuate nozzle headers 32. - Each of the
arcuate nozzle headers 32 is displaceable toward thesteel strip 1 by means of, for example, anair cylinder 34 so that a gap between thesteel strip 1 and thegas blowing nozzle 31 can be adjusted. Each of thegas blowing nozzles 31 having such a construction is provided stationarily or displaceably in the longitudinal direction of each of the cooling rolls 2 at a prescribed interval. - The apparatus of the sixth embodiment is identical with the apparatus of the first embodiment in that the
gas cooler 3 is arranged on the exit side of the plurality of cooling rolls 2, thefirst tension regulator 17 is arranged on the entry side of the plurality of cooling rolls 2, and thesecond tension regulator 18 is arranged on the exit side of thegas cooler 3. Aradiation thermometer 11a and amultiple reflection thermometer 11b as thethermometer 11 are provided on each of the entry side of thefirst tension regulator 17 and the exit side of thesecond tension regulator 18. A temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof, is continuously measured by means of theradiation thermometer 11a and themultiple reflection thermometer 11b provided on the exit side of thesecond tension regulator 18. Thedeflector roll 19 is provided on each of the entry side and the exit side of thegas cooler 3. In Fig. 25, 58 is a sealing roll provided at each of the entry and the exit of thegas cooler - Fig. 26 is a descriptive view illustrating the functions of the
radiation thermometer 11a and themultiple reflection thermometer 11b as thethermometer 11. Theradiation thermometer 11a measures a radiation temperature of thesteel strip 1 in the width direction thereof. Themultiple reflection thermometer 11b measures a true temperature of thesteel strip 1 on the surface thereof which is in contact with a roll. The true temperature of thesteel strip 1 measured by themultiple reflection thermometer 11b is transmitted to acomputer 60. The radiation temperature of thesteel strip 1 measured by theradiation thermometer 11a is on the other hand transmitted to athermal emissivity corrector 61. Thethermal emissivity corrector 61 corrects the measured value of the radiation temperature of thesteel strip 1 in the width direction thereof on the basis of the true temperature of thesteel strip 1 transmitted from thecomputer 60. The thus corrected radiation temperature of thesteel strip 1 in the width direction thereof is transmitted, for example, to thefirst comparator 13 shown in Fig. 2. - Fig. 27 is a graph illustrating a temperature distribution of a
steel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 under the same conditions as in the first embodiment by means of the apparatus of the sixth embodiment of the present invention as shown in Fig. 24. In Fig. 27, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents a temperature of thesteel strip 1 in the width direction thereof. As shown by the solid line in Fig. 27, the temperature of thesteel strip 1 in the width direction thereof on the exit side of thecooling roll 2e, is about 380°C at the side edge of thesteel strip 1, and is substantially equal to the target temperature for cooling of 350°C at a portion of about 10 mm from the side edge of thesteel strip 1. On the exit side of thegas cooler 3, as shown by the dotted line in Fig. 27, the temperature of thesteel strip 1 in the width direction thereof decreases to slightly lower than the target temperature for cooling of 350°C at a position of about 10 mm from the side edge of thesteel strip 1. - Fig. 28 is a graph illustrating an aging index (AI) of the above-mentioned
steel strip 1 in the width direction thereof. In Fig. 28, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of thesteel strip 1 in the width direction thereof. When cooling thesteel strip 1 by means of the apparatus of the sixth embodiment, as is clear from Fig. 28, there is no portion showing an aging index of over 4 kgf/mm², and the aging index is very low at the both side edges of thesteel strip 1. - Fig. 29 is a descriptive view illustrating a seventh embodiment of the apparatus of the present invention. As shown in Fig. 29, the apparatus of the seventh embodiment is identical with the apparatus of the first embodiment shown in Fig. 1, except that a
third tension regulator 35 comprising at least two bridle rolls is further arranged between the plurality of cooling rolls 2 and thegas cooler 3. - A temperature distribution and an aging index (AI) of a
steel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 by means of the apparatus of the seventh embodiment, is substantially the same as in the apparatus of the first embodiment shown in Fig. 1, and a detailed description thereof is omitted. - Fig. 30 is a descriptive view illustrating an eighth embodiment of the apparatus of the present invention. As shown in Fig. 30, the apparatus of the eighth embodiment comprises a
single cooling roll 36, which is freely rotatable and in contact with asteel strip 1 continuously travelling in the logitudinal direction thereof, for continuously cooling thesteel strip 1, agas cooler 3, arranged on the exit side of thesingle cooling roll 36, for continuously cooling thesteel strip 1 by blowing a cooling gas onto the surface of thesteel strip 1 so as to achieve a uniform temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof, afirst tension regulator 17, comprising at least two bridle rolls, arranged on the entry side of thesingle cooling roll 36, and asecond tension regulator 18, comprising at least two bridle rolls, arranged on the exit side of thegas cooler 3. - The
single cooling roll 36 is stationary relative to thesteel strip 1. Thesingle cooling roll 36 has a length at least equal to the width of thesteel strip 1, and a cooling liquid flows through the interior of thesingle cooling roll 36 to continuously cool thesingle cooling roll 36. Aguide roll 37 for controlling a contact area between the surface of thesingle cooling roll 36 and the surface of thesteel strip 1, is provided on each of the entry side and the exit side of thesingle cooling roll 36. Each of the guide rolls 37 is displaceable along the outer periphery of thesingle cooling roll 36 by means of a driving mechanism not shown. It is possible to control the contact area between the surface of thesingle cooling roll 36 and the surface of thesteel strip 1, by causing each of the guide rolls 37 to displace along the outer periphery of the single cooling rolls 36. - Fig. 31 is a graph illustrating a temperature distribution of a
steel strip 1 in the width direction thereof, when continuously cooling thesteel strip 1 under the same conditions as in the first embodiment by means of the apparatus of the eighth embodiment of the present invention as shown in Fig. 30. In Fig. 31, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents a temperature of thesteel strip 1 in the width direction thereof. As shown by the solid line in Fig. 31, the temperature of thesteel strip 1 in the width direction thereof on the exit side of thesingle cooling roll 36 is over the target temperature for cooling of 350°C in a portion within about 10 mm from the side edge of thesteel strip 1. On the exit side of thegas cooler 3, however, thesteel strip 1 shows a uniform temperature of about 350°C over the entire portion from the side edge to the center of thesteel strip 1, as shown by the dotted line in Fig. 31. - Fig. 32 is a graph illustrating an aging index (AI) of the above-mentioned
steel strip 1 in the width direction thereof. In Fig. 32, the abscissa represents a distance from the side edge of thesteel strip 1 toward the center in the width direction thereof, and the ordinate represents an aging index (AI) of thesteel strip 1 in the width direction thereof. As is clear from Fig. 32, the portion showing an aging index of over 4 kgf/mm² covers only about 10 mm from the side edge of thesteel strip 1, with a maximum aging index of 4.5 kgf/mm², thus the portion having an aging index of over 4 kgf/mm² is remarkably reduced as compared with theprior arts - Figs. 33(A) and 33(B) are flow diagrams illustrating a typical continuous annealing equipment of a steel strip incorporating the apparatus of the first embodiment of the present invention. As shown in Figs. 33(A) and 33(B), an
entry side looper 40, a preheatingzone 41, adirect heating zone 42, anindirect heating zone 43, a soakingzone 44, aslow cooling zone 45, afirst cooling zone 46 comprising the apparatus of the first embodiment of the present invention, an overaging zone (or a tempering zone; the same applies also hereafter) 47, asecond cooling zone 48, and anexit side looper 49 are arranged in this order between a plurality ofuncoilers 38 and a plurality ofcoilers 39. - In the
first cooling zone 46 comprising the apparatus of the first embodiment of the present invention, there are arranged afirst tension regulator 17, a plurality of cooling rolls 2, agas cooler 3, and asecond tension regulator 18 in this order. - Between the
second cooling zone 48 on the exit side of the overagingzone 47 and theexit side looper 49, there is arranged achemical pretreatment zone 54 for forming a film of nickel or a nickel alloy in a slight amount and an oxide film in a slight amount on the surface of the continuously annealedsteel strip 1 to improve chemical treatability and/or lubricity of thesteel strip 1. Between theexit side looper 49 and the plurality ofcoilers 39, there are arranged atemper rolling mill 55, atrimmer 56 and anoiler 57 in this order. - The
steel strip 1 continuously travelling in the logitudinal direction thereof, which has been uncoiled by any one of theuncoilers 38, cut at both ends in the longitudinal direction thereof by thecutter 50, and butt-welded at end faces by thewelder 51, is then cleaned on the both surfaces thereof in the cleaner 52, then guided to theleveller 53 which levels thesteel strip 1 so as to achieve a flat shape. This permit prevention of an abnormal travelling caused by a zigzag motion of thesteel strip 1 in theentry side looper 40, the preheatingzone 41, thedirect heating zone 42, theindirect heating zone 43, the soakingzone 44, etc., and a contact between thesteel strip 1 and the furnace wall or the burner. - The
steel strip 1, the shape of which has been levelled by theleveller 53, is introduced through theentry side looper 40 sequentially into the preheatingzone 41, thedirect heating zone 42, theindirect heating zone 43, the soakingzone 44 and theslow cooling zone 45. In the meantime, thesteel strip 1 is preheated, directly heated, indirectly heated, soaked, and then slowly cooled in accordance with a prescribed heat cycle. Through the above-mentioned preheating, direct heating, indirect heating and soaking, thesteel strip 1 is uniformly heated to a prescribed temperature with only a few irregularities in heating or thermal deformations. - Particularly, since the
steel strip 1 is rapidly heated in the above-mentioneddirect heating zone 42, thesteel strip 1 passes through an unstable thermal deformation region in a very short period of time. Therefore, thesteel strip 1 is less susceptible to the thermal deformation tending to occur during heating, and a zigzag motion of thesteel strip 1 travelling through thedirect heating zone 42 is prevented. - The
steel strip 1 slowly cooled to a prescribed temperature in theslow cooling zone 45 is then introduced into thefirst cooling zone 46, in which thesteel strip 1 is continuously cooled by the plurality of cooling rolls 2, and then continuously cooled by thegas cooler 3 so as to achieve a uniform temperature distribution in the width direction of thesteel strip 1 afrer the final cooling thereof. Because thesteel strip 1 has been levelled into a flat shape by theleveller 53, an insufficient contact of thesteel strip 1 with the plurality of cooling rolls 2 is prevented. - The
steel strip 1 cooled to a prescribed temperature in thefirst cooling zone 46 is then introduced into theoveraging zone 47, in which an overaging treatment is applied to thesteel strip 1. Since thesteel strip 1 has been cooled in the above-mentionedfirst cooling zone 46 so as to achieve a uniform temperature distribution in the width direction of thesteel strip 1 after the final cooling thereof, a defective shape such as edge waves or heat buckles does not occur in thesteel strip 1, and as a result, an abnormal travelling such as a zigzag motion never occurs in thesteel strip 1 which travels through theoveraging zone 47 as the next process. - The
steel strip 1 overaged in theoveraging zone 47 and cooled to a temperature not causing oxidation in thesecond cooling zone 48 is then introduced into thechemical pretreatment zone 54, in which a film of nickel or a nickel alloy in a slight amount is formed on the surface of thesteel strip 1 through a cathodic electrolysis treatment, and then, an oxide film in a slight amount is formed on the nickel or nickel alloy film through a dipping treatment in a neutral or alkaline bath. - Figs. 34(A), 34(B) and 34(C) are schematic flow diagrams each illustrating a typical
chemical pretreatment zone 54. In the embodiment shown in Fig. 34(A), thechemical pretreatment zone 54 comprises acooling tank 62, apickling tank 63, awater rinsing tank 64, a nickel-phosphorusalloy plating tank 65, anotherwater rinsing tank 64, ascrubber 66, a neutralizingtank 67, anotherscrubber 66, ahot water tank 68, and acold water tank 69. Thesteel strip 1 is introduced through thecooling tank 62, thepickling tank 63 and thewater rinsing tank 64 into the nickel-phosphorusalloy plating tank 65, in which a nickel-phosphorus alloy film in a slight amount is formed on the surface of thesteel strip 1 through a cathodic electrolysis treatment. Thesteel strip 1 on the surface of which the nickel-phosphorus alloy plating film has thus been formed is then introduced through the anotherwater rinsing tank 64, thescrubber 66, the neutralizingtank 67 and the anotherscrubber 66 into thehot water tank 68 and thecold water tank 69, in which an oxide film in a slight amount is formed on the nickel-phosphorus alloy plating film. - The embodiment shown in Fig. 34(B) is identical with that shown in Fig. 34(A), except that a
nickel plating tank 70 is provided in place of the above-mentioned nickel-phosphorusalloy plating tank 65. The embodiment shown in Fig. 34(C) is identical with that shown in Fig. 34(B), except that awater spray tank 71 is provided in place of the above-mentionedscrubber 66 and neutralizingtank 67. - The continuously annealed
steel strip 1 has a beautiful surface as a result of a direct flame reducing heating applied in thedirect heating zone 42, a heating in a weakly reducing atmosphere applied in theindirect heating zone 43 and the soakingzone 44, and a non-oxidizing cooling applied in thefirst cooling zone 46. However, thesteel strip 1 is not always satisfactory in chemical treatability and/or lubricity. This problem is solved by forming a nickel or nickel alloy film in a slight amount and an oxide film in a slight amount on the surface of thesteel strip 1 in thechemical pretreatment zone 54 as described above, thus permitting improvement of chemical treatability and/or lubricity of thesteel strip 1. - The
steel strip 1 to which the above-mentioned pretreatment has been applied in thechemical pretreatment zone 54 is then introduced through theexit side looper 49 into thetemper rolling mill 55, in which a temper rolling is applied to thesteel strip 1. Then, the side edges of thesteel strip 1 are trimmed by thetrimmer 56. After application of an anticorrosive oil by theoiler 57, thesteel strip 1 is coiled by any one of thecoilers 39 into a coil. - Since the
steel strip 1 after the final cooling thereof in the above-mentioned process has a uniform temperature distribution in the width direction thereof, thesteel strip 1 has substantially a uniform aging index in the width direction thereof. It is therefore possible to manufacture asteel strip 1 having uniform mechanical properties and excellent in quality. - The above description has mainly covered the apparatus of the present invention as to the cooling applied when continuously annealing a steel strip comprising an ordinary aluminum-killed steel. However, the apparatus of the present invention is applicable also, for example, for the cooling when continuously hardening or tempering a steel strip comprising a high tensile steel, the cooling when continuously annealing a steel strip comprising an aluminum-killed steel containing at least one of titanium, niobium, zirconium, vanadium and boron in a slight amount to fix carbon or nitrogen in steel, the cooling applied to a continuously annealed steel strip on the entry side of a hot-dip plating tank in a continuous hot-dip plating equipment, and the cooling applied to a hot-dip plated steel strip on the exit side of a hot-dip plating tank.
- According to the apparatus of the present invention, as described above in detail, it is possible to provide, when continuously cooling a metal strip continuously travelling in the longitudinal direction thereof by means of at least one cooling roll and a gas cooler, an apparatus for continuously cooling a metal strip, which permits prevention of the occurrence of a defect such as edge waves, heat buckles or scratches in the metal strip and an abnormal travelling of the metal strip such as a zigzag motion in the next process, requires only limited installation and running costs of the gas cooler, and makes available a high-quality metal strip having uniform mechanical properties in the width direction thereof, through achievement of a uniform temperature distribution of the metal strip in the width direction thereof, thus providing industrially useful effect.
Claims (12)
- In an apparatus for continuously cooling a metal strip, which comprises:
at least one cooling roll, which is freely rotatable and in contact with a metal strip continuously travelling in the longitudinal direction thereof, for continuously cooling said metal strip, said cooling roll having a length at least equal to the width of said metal strip, a cooling liquid flowing through the interior of said cooling roll to continuously cool same, and a contact area between the surface of said cooling roll and the surface of said metal strip being controllable; and
a gas cooler, arranged on the exit side of said at least one cooling roll, for continuously cooling said metal strip by blowing a cooling gas onto the surface of said metal strip so as to achieve a uniform temperature distribution in the width direction of said metal strip after the final cooling thereof, said gas cooler being arranged in the width direction of said metal strip at a prescribed distance from each of the both surfaces of said metal strip, said gas cooler comprising a plurality of mutually independent nozzle headers for blowing said cooling gas onto the surface of said metal strip, and said plurality of nozzle headers controlling at least one of a flow rate and a flow velocity of said cooling gas in the width direction of said metal strip;
the improvement wherein:
a first tension regulator comprising at least two rolls is arranged on the entry side of said plurality of cooling rolls, and a second tension regulator comprising at least two rolls is arranged on the exit side of said gas cooler. - An apparatus as claimed in Claim 1, wherein:
a thermometer, for continuously measuring a temperature distribution in the width direction of said metal strip after the final cooling thereof, is provided on the exit side of said gas cooler, and at least one of said flow rate and said flow velocity of said cooling gas blown from said plurality of nozzle headers of said gas cooler onto the surface of said metal strip, is controlled on the basis of said temperature distribution measured by said thermometer. - An apparatus as claimed in Claim 1, wherein:
said cooling gas comprises a hydrogen gas in an amount within a range of from 40 to 90 vol.% and a nitrogen gas in an amount within a range of from 10 to 60 vol.%. - An apparatus as claimed in Claim 1, wherein:
said at least one cooling roll comprises a plurality of cooling rolls, the respective axes of which are in parallel with each other, and each of said plurality of cooling rolls is displaceable toward said metal strip to control said contact area with said metal strip. - An apparatus as claimed in Claim 4, wherein:
said contact area between the surface of each of the first-half cooling rolls from among said plurality of cooling rolls and the surface of said metal strip, is larger than said contact area between the surface of each of the latter-half cooling rolls from among said plurality of cooling rolls and the surface of said metal strip. - An apparatus as claimed in Claim 4 or 5, wherein:
another gas cooler, for continuously cooling said metal strip by blowing a cooling gas onto the surface of said metal strip so as to achieve a uniform temperature distribution in the width direction of said metal strip after the final cooling thereof, is arranged between said first tension regulator and said plurality of cooling rolls. - An apparatus as claimed in Claim 4 or 5, wherein:
another gas cooler, for continuously cooling said metal strip by blowing a cooling gas onto the surface of said metal strip so as to achieve a uniform temperature distribution in the width direction of said metal strip after the final cooling thereof, is arranged in the middle portion of said plurality of cooling rolls. - An apparatus as claimed in Claim 4 or 5, wherein:
another gas cooler, for continuously cooling said metal strip by blowing a cooling gas onto the surface of said metal strip so as to achieve a uniform temperature distribution in the width direction of said metal strip after the final cooling thereof, is arranged between said first tension regulator and said plurality of cooling rolls, and further another gas cooler, for continuously cooling said metal strip by blowing a cooling gas onto the surface of said metal strip so as to achieve a uniform temperature distribution in the width direction of said metal strip after the final cooling thereof, is arranged in the middle portion of said plurality of cooling rolls. - An apparatus ads claimed in Claim 4 or 5, wherein:
a plurality of gas blowing nozzles, each of which is directed toward a contact face between the surface of each of said plurality of cooling rolls and the surface of said metal strip, are provided on the side of said cooling rolls, and each of said plurality of gas blowing nozzles continuously cools said metal strip by blowing a cooling gas onto the surface of said metal strip so as to achieve a uniform temperature distribution in the width direction of said metal strip after the final cooling thereof. - An apparatus as claimed in Claim 4 or 5, wherein:
a plurality of gas blowing nozzles, each of which is directed toward a contact face between the surface of each of said plurality of cooling rolls and the surface of said metal strip, are provided on the side of said metal strip, and each of said plurality of gas blowing nozzles continuously cools said metal strip by blowing a cooling gas onto the surface of said metal strip so as to achieve a uniform temperature distribution in the width direction of said metal strip after the final cooling thereof. - An apparatus as claimed in Claim 4 or 5, wherein:
a third tension regulator comprising at least two rolls is arranged between said plurality of cooling rolls and said gas cooler. - An apparatus as claimed in Claim 1, wherein:
said at least one cooling roll comprises a single cooling roll, said single cooling roll is stationary relative to said metal strip, a guide roll for controlling said contact area between the surface of said single cooling roll and the surface of said metal strip, is provided on each of the entry side and the exit side of said single cooling roll, each of said guide rolls is displaceable along the outer periphery of said single cooling roll, a first tension regulator comprising at least two rolls is arranged on the entry side of said single cooling roll, and a second tension regulator comprising at least two rolls is arranged on the exit side of said gas cooler.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2202725A JP2592175B2 (en) | 1990-07-31 | 1990-07-31 | Strip cooling device |
JP202725/90 | 1990-07-31 | ||
PCT/JP1991/001009 WO1992002645A1 (en) | 1990-07-31 | 1991-07-26 | System for continuously cooling metal strip |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0495115A1 true EP0495115A1 (en) | 1992-07-22 |
EP0495115A4 EP0495115A4 (en) | 1993-03-17 |
EP0495115B1 EP0495115B1 (en) | 1996-11-06 |
Family
ID=16462130
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP91913119A Expired - Lifetime EP0495115B1 (en) | 1990-07-31 | 1991-07-26 | System for continuously cooling metal strip |
Country Status (9)
Country | Link |
---|---|
EP (1) | EP0495115B1 (en) |
JP (1) | JP2592175B2 (en) |
KR (1) | KR950004711B1 (en) |
AT (1) | ATE145012T1 (en) |
BR (1) | BR9105852A (en) |
DE (1) | DE69123038T2 (en) |
ES (1) | ES2096656T3 (en) |
WO (1) | WO1992002645A1 (en) |
ZA (1) | ZA915774B (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR20020051080A (en) * | 2000-12-22 | 2002-06-28 | 이구택 | A system for cooling hot steel plate |
CN106882651B (en) | 2011-05-18 | 2019-08-16 | 魁北克水电公司 | Ferromagnetic metallic ribbon conveying equipment and method |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0230780A1 (en) * | 1985-12-24 | 1987-08-05 | Kawasaki Steel Corporation | Steel strip cooling method |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS58213833A (en) * | 1982-06-03 | 1983-12-12 | Nippon Kokan Kk <Nkk> | Continuous annealing furnace |
JPS59136427A (en) * | 1983-01-21 | 1984-08-06 | Sumitomo Metal Ind Ltd | Method for cooling thin steel plate by rolling |
JPS60135532A (en) * | 1983-12-22 | 1985-07-18 | Kawasaki Steel Corp | Cooler for strip |
JPS60169524A (en) * | 1984-02-14 | 1985-09-03 | Mitsubishi Heavy Ind Ltd | Cooler for metallic strip |
JPS61194119A (en) * | 1985-02-21 | 1986-08-28 | Nippon Steel Corp | Cooling installation train for steel strip |
JPS6267125A (en) * | 1985-09-20 | 1987-03-26 | Kawasaki Steel Corp | Method for cooling steel strip in continuous annealing furnace |
-
1990
- 1990-07-31 JP JP2202725A patent/JP2592175B2/en not_active Expired - Fee Related
-
1991
- 1991-07-23 ZA ZA915774A patent/ZA915774B/en unknown
- 1991-07-26 DE DE69123038T patent/DE69123038T2/en not_active Expired - Lifetime
- 1991-07-26 AT AT91913119T patent/ATE145012T1/en not_active IP Right Cessation
- 1991-07-26 WO PCT/JP1991/001009 patent/WO1992002645A1/en active IP Right Grant
- 1991-07-26 BR BR919105852A patent/BR9105852A/en not_active IP Right Cessation
- 1991-07-26 KR KR1019920700626A patent/KR950004711B1/en not_active IP Right Cessation
- 1991-07-26 EP EP91913119A patent/EP0495115B1/en not_active Expired - Lifetime
- 1991-07-26 ES ES91913119T patent/ES2096656T3/en not_active Expired - Lifetime
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0230780A1 (en) * | 1985-12-24 | 1987-08-05 | Kawasaki Steel Corporation | Steel strip cooling method |
Non-Patent Citations (1)
Title |
---|
See also references of WO9202645A1 * |
Also Published As
Publication number | Publication date |
---|---|
DE69123038T2 (en) | 1997-04-10 |
ZA915774B (en) | 1992-04-29 |
EP0495115A4 (en) | 1993-03-17 |
JP2592175B2 (en) | 1997-03-19 |
KR950004711B1 (en) | 1995-05-04 |
WO1992002645A1 (en) | 1992-02-20 |
EP0495115B1 (en) | 1996-11-06 |
BR9105852A (en) | 1992-09-29 |
ES2096656T3 (en) | 1997-03-16 |
KR920702428A (en) | 1992-09-04 |
ATE145012T1 (en) | 1996-11-15 |
DE69123038D1 (en) | 1996-12-12 |
JPH0488128A (en) | 1992-03-23 |
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