JP2715683B2 - Roll cooling method and apparatus for continuous annealing furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for cooling a roll of a continuous annealing furnace.

[0002]

2. Description of the Related Art When a metal strip is unevenly cooled in a sheet width direction in a roll cooling device of a continuous annealing furnace, the shape of the metal strip collapses, and meandering, drawing, and the like occur in a subsequent overaging furnace. As a result, the stable operation of the furnace is significantly impaired.

Japanese Patent Publication No. 62-67125 proposes the following configuration as a technique for preventing such nonuniform cooling of the metal strip in the plate width direction. In the same article, first, the uneven cooling in the metal strip width direction in the roll cooling device is caused by the fact that the contact between the metal strip edge and the cooling roll is deteriorated by the thermal crown generated by the cooling roll, and the edge is not cooled. For this purpose, as shown in FIG. 3, a group of cooling rolls 10 is separated into a front stage and a rear stage, and a gas jet nozzle having a variable flow rate in the width direction is provided therebetween.
11 is provided to propose a configuration for stabilizing the contact between the metal strip X and the cooling roll 10 (particularly, contact at the edge portion).

[0004]

However, the cooling roll
The structure 10 generally has a spiral groove inside and a coolant such as cooling water passes through the groove, so that the thermal crown should not originally occur. Also, the bridle rolls 50 and 60 are arranged at the inlet and the outlet of the roll cooling device to apply a constant tension to the metal band X.
It is unlikely that the contact between the cooling roller 10 and the cooling roller 10 becomes uneven. As described above, the technique of the same issue does not completely elucidate the cause of the non-uniform cooling, so that the problem of non-uniform cooling in the width direction of the metal strip has not yet reached an essential solution.

On the contrary, in the above prior art, the heat transfer coefficient at the gas jet nozzle 11 is low,
By providing such a gas jet device in the middle stage of the roll cooling facility, a long path is required, and as a result, the average cooling rate in the roll cooling facility is reduced, and the solid solution C of the metal strip such as a steel plate is over-aged. It becomes difficult to precipitate to a level that does not cause any problem.

Further, in the configuration of the above-mentioned prior art, since the cooling roll 10 has a fixed roll configuration, when the load of the cooling roll 10 is changed, the roll winding length cannot be changed, and a predetermined heat cycle is performed. I can't keep it.
For this reason, there is also a drawback that only materials having a large variation in material can be produced.

The present invention has been made in view of the above-mentioned problems of the prior art, and clarifies a main cause of uneven cooling of a metal strip in a sheet width direction in a roll cooling device. The present invention provides a roll cooling method and a roll cooling method that do not generate a non-uniform cooling, prevents a metal strip from being deformed in shape, and enables a stable operation of a continuous annealing furnace.

[0008]

Therefore, a roll cooling method for a continuous annealing furnace according to the present invention is directed to a method of cooling a plurality of cooling rolls having a structure in which a spiral groove is formed inside and a coolant passes through the groove. The basic feature is that the attachment length is controlled so as to be longer in the front roll that comes into contact with the metal strip having a high sheet temperature, and to be shorter in the rear roll that has a lower sheet temperature.

[0009] The second invention relates to a proposal of a configuration of an apparatus for implementing the first invention method. Specifically, the second configuration has a spiral groove through which a refrigerant passes, and its surface is brought into continuous contact. A plurality of cooling rolls for cooling the metal strip, a sheet thermometer for measuring the inlet sheet temperature and the outlet sheet temperature of the metal strips on the inlet side and the outlet side of the group of cooling rolls, and each cooling roll for the metal strip. A push adjuster that adjusts the push amount,
The outlet measured plate temperature output from the plate thermometer is compared with the target outlet plate temperature, and each push amount of the cooling roll group is calculated based on the inlet measured plate temperature and the target outlet plate temperature to adjust each push. A plurality of cooling rolls, each of which has a plurality of cooling rolls, the length of which is increased by the front roll and shortened by the rear roll. The control of the adjuster is performed.

[0010] The above-described configuration is based on the present inventors' elucidation of a new cause of the non-uniform cooling in the direction of temperature of the metal strip of the roll cooling equipment, and the invented cause is as follows. Will be described first.

When the sheet material A is bent as shown in FIG. 1 (a), a tensile and compressive stress distribution occurs in the sheet thickness direction as shown in FIG. 1 (b). As shown in FIG. 3A, a reverse compression and tensile stress distribution is induced in a direction perpendicular to the direction, and reverse bending deformation occurs in a direction perpendicular to the main bending. It is considered that the same occurs when the metal band is wound around the cooling roll, and it is assumed that such a saddle-shaped deformation causes poor contact at the edge portion. Insufficient cooling due to poor contact at the edge produces uneven temperature distribution in the width direction of the metal strip. The distribution of the heat shrinkage strain due to the non-uniform temperature distribution generates a tension distribution, and the edge portion is further raised. Thereafter, it is considered that the lifting and the generation of the heat shrinkage strain are repeated, and the uneven cooling in the width direction of the metal strip is increased. FIG. 2 shows a state in which the lifting phenomenon of the metal band edge portion due to such saddle type deformation is increased,
When the metal band X comes into contact with the first roll 1a shown in the upper part of the drawing, the lifting of the edge portion is also in a very narrow range, but the second roll 1b, the third roll 1c,..., The sixth roll 1f. (H in the figure indicates the edge floating width, and the portion surrounded by the broken line indicates the portion that was not completely cooled by the preceding roll. Shown).

In particular, the floating width of the metal band edge caused by such saddle-shaped deformation varies depending on the roll winding length pattern of the cooling roll group. For example, the roll diameter D is 1600 mm, the strip thickness t is 1 mm, and the width W is 12
20mm, Lines Speed LS 195mpm, Processing capacity: 110T
/ H, Roll cooling equipment inlet plate temperature: 600 ° C, outlet plate temperature: 400
Under cooling conditions of ° C., the experiment was performed by changing the roll winding length pattern from the first cooling roll to the seventh cooling roll to a pattern in which the roll winding length becomes larger toward the later roll as shown in FIG. Was. When such a pattern is set, the temperature drop of the strip becomes larger as the roll at the later stage becomes larger, but the sheet temperature profile of the edge portion at each roll exit at this time is as shown in FIG. The one extending in the horizontal direction is the inlet plate temperature profile, the end of the first roll 1a at the edge portion is the same as the inlet plate temperature, and the other portions in contact with the rolls are slightly less than the inlet plate temperature. Although the temperature drops, the cooling amount in the cooling rolls at the subsequent stage after the second roll 1b becomes larger, so that the sheet temperature drop in the portion in contact with the rolls becomes larger, and the rising phenomenon of the edge portion shown in FIG. Overlap with each other to amplify a non-uniform temperature distribution phenomenon in the width direction of the strip plate). When the high temperature portion reaches the central portion of the plate width, the rising width H of the edge portion gradually enters the central portion of the plate width each time it passes through the roll group. It gets into the center and loses its shape, causing meandering and squeezing.

The inventors of the present invention have elucidated the mechanism of the cause of the non-uniform cooling in the width direction of the metal strip as described above. Therefore, the inventors of the present invention have made the above-described configuration of the present invention. . That is, when the pattern shown in FIG. 3 is changed to the roll winding length pattern of the cooling roll group as shown in FIG. 5 (the roll cooling condition is the same as the roll cooling condition shown in FIG. 3) ( That is, as shown in FIG. 6, when the roll winding length of the front roll is increased, the amount of cooling of the front roll having a small edge lift is increased, and the temperature of the edge portion from the beginning of cooling is increased. The metal band can be lowered, and the region of the metal strip in the non-uniform cooling in the plate width direction is suppressed to a small range. Therefore, ear waves are also generated only in a narrow range on the edge side, and meandering or narrowing of the metal band hardly occurs.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 7 shows an embodiment of the roll cooling apparatus according to the second aspect of the present invention, which is an apparatus for implementing the method of the present invention. In the figure, X is a strip to be cooled, and 1a to 1g are cooling water inside. Rolls with spiral grooves, 2a and 2b
Is a multiple reflection type plate thermometer for measuring the sheet temperature on the inlet side and the sheet temperature on the outlet side of the cooling roll group, respectively, 3a to 3g is a push adjusting machine for adjusting the pushing amount of each cooling roll 1a to 1g with respect to the strip X, 4 is an arithmetic unit that inputs the measured values of both sheet thermometers 2a and 2b and controls the roll pushing amount of each of the push adjusting machines 3a to 3g,
In addition, reference numerals 5a to 5c and 6a to 6c indicate an entrance bridle roll and an exit bridle roll, respectively.

The roll cooling condition of the roll cooling device is as follows. First, the size of the strip X to be cooled is determined by the thickness t.
= 1 mm, plate width W = 1220 mm, the roll diameter D of the cooling rolls 1a to 1g was 1600 mm, the line speed LS was 195 mpm, and the processing capacity was 110 T / H.

The arithmetic unit 4 always receives the inlet-side sheet temperature and the outlet-side sheet temperature by the sheet thermometers 2a and 2b, and furthermore, the outlet sheet temperature of the strip X controlled by cooling by these cooling rolls is 400 ° C. The target outlet plate temperature is set in advance such that Then, a difference between the outlet measured plate temperature input from the plate thermometer 2b and the target outlet plate temperature is obtained,
In addition, the inlet measurement plate temperature (approximately 600
℃, and the cooling roll load K ｛= ΔT × t × LS, ΔT: cooling amount (° C.)｝ is calculated based on the target outlet plate temperature. At the time of this calculation, the plate thickness t of the strip X and the line speed LS are input to the calculation device 4.

When the cooling roll load K is determined, the roll winding length L is determined by the following equation (1) in the facility of this embodiment. L = 0.128K / 1000-0.4871 ... (1)

As described above, K = ΔT × t × LS.
Equation (1) becomes as in the following equation (2). ΔT = (L + 0.4871) × (1000 / 0.1218) × (1 / t ·
LS) ... (2)

Therefore, the cooling amount ΔT is proportional to the roll winding length L.

When the roll winding length L is determined by these calculations, the distribution of the individual winding lengths of the cooling rolls 1a to 1g is determined next. It is set so that the former roll is always longer than the winding length of the latter roll (it may be equal in a specific case).

FIGS. 8 to 10 show the first cooling roll at this time.
FIGS. 8A and 8B show examples of distribution adjustment of the roll winding length of each roll of 1a to 7th cooling roll 1g. FIG. 8 shows distribution adjustment when all rolls are used, and FIG. FIG. 10 shows the distribution adjustment when the first cooling roll 1a and the seventh cooling roll 1g are not used.

The uppermost stage in FIG. 8 shows a state in which the amount of pushing of the first cooling roll 1a is 50% (the winding length is 50%), and the lower stage shows the amount of pushing in of the first cooling roll 1a. The state when the pushing amount of the second cooling roll 1b becomes 50% after the pressure becomes 100%, and further ... In the lowermost stage, after the roll pushing amount up to the sixth cooling roll 1f reaches 100%. 7th cooling roll 1
The state when the pushing amount of g becomes 50% is shown. In these adjustments, the roll immediately after the roll being adjusted is always in contact with the strip X. This stabilizes the strip contact end point of the roll being adjusted, and the winding length This was performed with the aim of improving the adjustment accuracy.

FIG. 9 shows an example of the roll winding length distribution adjustment when the first cooling roll 1a is not used as described above. At this time, the second cooling roll 1b is moved to the next third cooling roll 1b. Cooling roll
It is used only as a presser roll for stabilizing the starting point of contact of the strip X of 1c and improving the accuracy of adjusting the roll winding length. Therefore, the adjustment of the roll winding length starts from the third cooling roll 1c, and the specific distribution adjustment is in accordance with the case of FIG.

Also in this case, the roll immediately after the roll whose winding length is being adjusted is also in contact with the strip X. However, as described above, the end of the strip contact of the roll whose winding length is being adjusted is stabilized. It is intended to improve the adjustment accuracy.

FIG. 10 shows an example in which the first cooling roll 1a and the seventh cooling roll 1g are not used as described above. In this case, the sixth cooling roll 1f is connected to the strip of the fifth cooling roll 1e. Since it is only used for stabilizing the contact end point (contacting the strip X), the third cooling roll 1c is eventually used.
To fifth cooling roll 1e adjustment (winding length adjustment)
Will only be performed.

When the roll winding length pattern adjustment as described above was performed, the narrowing and meandering of the strip X caused by the shape collapse caused by the pattern adjustment as shown in FIG. 3 did not occur in the overaging furnace. The furnace operation became very stable.

FIG. 11 and FIG. 12 are sectional views showing a furnace configuration of a continuous annealing furnace to which a configuration according to another embodiment of the present invention is applied. In FIG. The configuration in which the gas jet cooling device 7 is installed is shown in FIG.
FIG. 2 shows a configuration in which two gas jet cooling devices 7a and 7b are similarly installed behind a horizontal roll cooling facility.

[0029]

As described above in detail, according to the method or apparatus of the present invention, the distribution adjustment of the roll winding length of the cooling roll group is optimized so that uneven cooling in the metal-to-board width direction does not occur. Therefore, the occurrence of shape collapse of the metal strip can be prevented, and stable operation of the continuous annealing furnace can be achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the principle of saddle-shaped deformation of a plate material due to bending.

FIG. 2 is an explanatory view showing an edge floating phenomenon due to saddle type deformation in a cooling roll.

FIG. 3 is an explanatory diagram showing an example of a roll winding pattern in which the roll winding length becomes longer as a subsequent roll is rolled.

FIG. 4 is an explanatory diagram showing an edge plate temperature profile at each cooling roll outlet at the time of the pattern.

FIG. 5 is an explanatory diagram showing an example of a roll winding pattern in which the roll winding length becomes longer as the front roll becomes longer.

FIG. 6 is an explanatory diagram showing an edge plate temperature profile at each cooling roll outlet at the time of the pattern.

FIG. 7 shows a second strip installed in a continuous annealing furnace for strip.
It is a schematic diagram showing one embodiment of a roll cooling device of the present invention.

FIG. 8 is an explanatory diagram showing an example of a roll winding length distribution adjustment in the apparatus of the present embodiment.

FIG. 9 is an explanatory diagram showing another example of the roll winding length distribution adjustment.

FIG. 10 is an explanatory view showing still another example of the roll winding length distribution adjustment.

FIG. 11 is a schematic view showing another embodiment in which the roll cooling device of the second invention is installed vertically and a gas jet cooling device is provided thereafter.

FIG. 12 is a schematic view showing still another embodiment configuration in which the roll cooling device of the second invention is installed in a horizontal type, and two gas jet cooling devices are provided after the roll cooling device.

FIG. 13 is an explanatory view showing a conventional technique for preventing uneven cooling of a metal strip in a plate width direction.

[Explanation of symbols]

 1a to 1g, 10 Cooling roll 2a, 2b Sheet thermometer 3a to 3g Indentation adjuster 4 Processing unit X Metal strip (strip)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masafumi Suzuki 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Hiroaki Sato 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan (72) Inventor Hitoshi Oishi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Naoto Kitagawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. 72) Inventor Takaya Seike 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Yasuhiro Araki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (56) References JP-A-60-159127 (JP, A) JP-A-59-104435 (JP, A) JP-A-56-35730 (JP, A)

Claims (2)

(57) [Claims] The cooling roll is continuously brought into contact with a metal strip in a continuous annealing furnace having a plurality of cooling rolls each having a spiral groove inside and having a structure in which a refrigerant passes through the groove. In a roll cooling method for a continuous annealing furnace that cools a strip, a plurality of cooling rolls are controlled such that a length of a metal strip wound around a plurality of cooling rolls is increased for a roll on a front side and shortened for a roll on a rear side. Roll cooling method for continuous annealing furnace. 2. A plurality of cooling rolls each having a spiral groove through which a refrigerant passes, and cooling the metal strip by continuously contacting the surfaces thereof, and a plurality of cooling rolls on an inlet side and an outlet side of the cooling roll group. A sheet thermometer for measuring the inlet sheet temperature and the outlet sheet temperature of the metal strip, a push adjuster for adjusting the pushing amount of each cooling roll to the metal strip, and an outlet measured sheet temperature and target output from the sheet thermometer. An arithmetic unit for comparing the outlet plate temperature, and calculating each indentation amount of the cooling roll group based on the inlet measured plate temperature and the target outlet plate temperature to control each indentation adjuster; A continuous annealing furnace characterized in that the control unit controls each indentation adjusting machine so that the length of the metal band wound around the cooling roll is longer in the first roll and shorter in the second roll. Roll cooling device.