JP2003117605A - Hot-rolling line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly strengthen the product of a metallic strip more than conventional products even in the case that the total draft in finish rolling is made equal and also to prevent the impossibility of continuation of transportation by the collision of the tip and the surface defects such as dents on a product without using a leveler which is not necessary to highly strengthen by making the movement of a leveler to be performed easily and rapidly. SOLUTION: In the hot-rolling line for metallic strip, a finishing mill, the leveler and a cooling system are arranged in this order from the upstream side of the rolling line toward the downstream side in the hot-rolling line of a metallic strip and a means for making the leveler off-line and on-line by moving the leveler in the direction crossing the rolling line is installed on this hot-rolling line.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a hot rolling line for producing high strength metal strips.

[0002]

2. Description of the Related Art A metal strip is manufactured by rolling in a hot rolling line in which a finishing rolling mill is arranged. For example, in a hot rolling line for producing steel strip, as schematically shown in FIG. 12, a heated metal piece S called a slab is roughly rolled by a rough rolling mill 2 and then rolled by a finish rolling mill 3. Then, the metal strip 1 is subjected to a predetermined cooling by the cooling equipment 4, and is wound around one of the coilers 5a and 5b in a coil shape to obtain a metal strip product. The slab may be heated in a heating furnace (not shown) for extraction, or may be directly sent in a hot state from the above process without passing through the heating furnace. Further, in some cases, the steel strip product may be manufactured by directly supplying the sheet bar to the finish rolling mill 3 and omitting the rough rolling. The finish rolling mill 3 has a plurality of rolling stands, and the work roll 3a and the backup roll 3b are incorporated in a rolling stand (not shown). Further, reference numeral 20 in the drawing denotes pinch rolls installed on the respective entrance sides of the coilers 5a and 5b.

In order to increase the strength of the steel strip product manufactured in this way, various hot rolling methods for refining crystal grains have been studied. As a typical example thereof, there is a so-called controlled rolling method disclosed in JP-A-63-223124. The principle of the controlled rolling method is that austenite (hereinafter simply referred to as γ) → ferrite (hereinafter simply referred to as α) transformation becomes α nucleation site, γ
By introducing a large amount of lattice defects such as grain boundaries and dislocations during rolling, a large number of α grains are generated during the γ → α transformation, and it is intended to realize the refinement of crystal grains.
Since the thickness of the metal piece and the product thickness are fixed, there is a limit to the amount of strain that can be introduced before the γ → α transformation by rolling, and it is generally said that the average grain size of 5 μm is the limit in the controlled rolling method. ing.

[0004]

Therefore, the present inventors previously proposed a hot rolling method for overcoming this limit in Japanese Patent Application No. 2001-302509 to obtain a product having higher strength than ever before, and A hot rolling line was proposed. The method proposed by the inventors of the present invention includes a finish rolling mill, a leveler, and a cooling facility in a hot rolling line in which the rolling line is arranged in this order from the upstream side to the downstream side of the rolling line. This is a hot rolling method in which the metal is repeatedly bent and then cooled, and even if the plate thickness of the metal strip and the metal strip product are the same, it is possible to refine the crystal grains of the structure of the metal strip product. It is a technology.

The leveler installed between the finish rolling mill of the hot rolling line and the cooling equipment was fixedly installed at that position, so that the leveler-free product (leveler-free material) which does not require high strength is used. When manufacturing the, there was a case in which a useless obstacle such as an inability to continue the transportation due to a bump was caused when the tip passed. To avoid this, even if the gap between the upper and lower rolls of the leveler is widened to allow the tip to pass, the scale dust accumulated on the upper roll of the leveler scatters from the cooling equipment installed in the zone with the hot run table. Adsorbs the cooling water and water vapor generated during cooling of the metal strip and solidifies into foreign matter.
When the leveler-free material passes through the leveler, the foreign substances fall onto the metal strip due to vibration and are not completely washed by the cooling water supplied from the cooling equipment. In some cases, the pinch roll may push the metal strip to the surface of the metal strip to cause surface defects such as indentation flaws of the metal strip product, and it has been desired to improve this point.

Further, in a hot rolling line provided with a leveler, depending on the type of product, rather than increasing the strength, it is desired to correct the shape of the metal strip by the leveler to improve the flatness of the metal strip, Alternatively, there are things such as adding cracks to the oxide scale on the surface of the metal strip with a leveler to improve the descaling property in the pickling line that is the next step of hot rolling. In some cases, it may be more convenient to be in the middle of the cooling equipment or between the cooling equipment and the pinch rolls, and it is secondly necessary to install the leveler at an appropriate position in the length direction of the rolling line according to the required quality of the product. Was wanted.

It is an object of the present invention to solve the first problem and the second problem.

[0008]

The present invention is a hot rolling line as described below. (1) In a hot rolling line for metal strips, a finishing rolling mill, a leveler, and a cooling facility are installed in this order from upstream to downstream, and the leveler is online so as to intersect with the hot rolling line. It is characterized in that means for making it offline are installed, and the first object is achieved by this configuration. (2) In the hot strip rolling line for metal strips, a leveler is arranged on the downstream side of the finish rolling mill, and means for moving the leveler along the length direction of the hot rolling line is installed. The second feature of this configuration is
To achieve the purpose of. (3) In the hot strip rolling line for metal strips, a leveler is arranged on the downstream side of the finish rolling mill, and a means for making the leveler online and offline so as to intersect the hot rolling line is installed. A means for moving along the length direction of the hot rolling line is provided, and this configuration achieves the first and second objects. (4) In any one of the hot rolling lines described above, it is preferable that a fill-in table roller is installed in an empty space of the hot run table that is vacant by taking the leveler off-line. (5) In a hot strip rolling line for metal strips, a finish rolling mill, a leveler, and a cooling facility are arranged in this order from upstream to downstream, and the leveler has an upper part and a lower part that are detachable from each other, and The lower part of the leveler is configured as a part of a fixed hot run table, and means for making the upper part of the leveler online and offline so as to intersect with the hot rolling line is installed. I tried to achieve the purpose. (6) In a hot strip rolling line for metal strips, a leveler is arranged on the downstream side of the finishing mill so that the upper part and the lower part can be detached from each other, and the lower part of the leveler is configured as a part of a fixed hot run table. Means for moving along the length direction of the hot rolling line is installed, and the second object is achieved by this configuration. (7) In a hot strip rolling line for metal strips, a leveler is arranged on the downstream side of the finishing mill so that the upper part and the lower part can be freely attached to and detached from each other, and the lower part of the leveler is configured as a part of a fixed hot run table. Is installed so as to cross the hot rolling line online and offline, and means for moving the leveler upper part along the length direction of the hot rolling line is installed. With this configuration, the first and second objects are achieved. (8) In any one of the hot rolling lines described above, it is preferable that cooling equipment is installed between the finish rolling mill and the leveler. (9) In any one of the above hot rolling lines, joining equipment is arranged upstream of the finish rolling mill, and
It is more preferable that cutting equipment is installed between the cooling equipment and the coiler installed downstream of the leveler.

The metal strip referred to in the present invention includes a metal plate.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION First, an example of a hot rolling line for rolling a metal strip according to the present invention will be described with reference to FIGS. 1 and 2. In FIG. 1, 3c is a finish rolling mill 3.
Of the final rolling stand, the finishing rolling mill 3, the cooling equipment 4, the pinch rolls 20 and the coilers 5a and 5b are the same as those installed in the conventional hot rolling line (see FIG. 12). The same reference numerals are given and the description is omitted. A group of rolls 60a for transporting metal strips arranged in a large number from the downstream of the finish rolling mill 3C to the coiler 5a constitutes a hotline table 60 as a whole.

The hot rolling line according to this embodiment is
The finish rolling mill 3, the leveler 6, and the cooling equipment 4 are arranged in this order from the upstream side to the downstream side of the rolling line. A second cooling facility 7 may be arranged between the finish rolling mill 3 and the leveler 6 as shown by a chain double-dashed line in FIG. As shown in FIG. 2, the leveler applied to the present invention is provided with three or more work rolls 6a arranged in a staggered pattern.

Here, the leveler 6 is constructed so that it can be opened or pushed through the leveler pushing means to adjust the roll pushing amount δ (see FIGS. 2A and 2B) of the leveler. . For example, the leveler pushing means may be an elevating device equipped with a screw that moves up and down by a worm speed reducer or an elevating device equipped with a hydraulic cylinder containing a cylinder rod that moves up and down by pressure oil and a position detector that detects the position of the cylinder rod. You can The bearing box that rotatably supports the work rolls 6a is lifted by such an elevating device.
Alternatively, the number of frames on the lower side is integrally raised and lowered.

Either one or both of the upper side and the lower side may be moved up or down, but any form may be adopted, but from the viewpoint of flattening the pass line of the metal strip and the simplicity of the leveler mechanism, the upper roll group It is particularly preferable to raise and lower the frame integrally with each other. By the leveler 6 provided with such three or more work rolls 6a, the passing metal strip 1 is repeatedly bent to add bending strain. The leveler work rolls 6a are preferably driven.

In the case of steel strip, the temperature at which the leveler is repeatedly bent is set to the γ → α transformation completion temperature or higher. At that time, in a temperature range exceeding the _{Ar 3} point (γ → α transformation start temperature during cooling), the bending may be repeatedly performed in the state of the metallic structure of only γ grains, or,
In the temperature range during the γ → α transformation, a few α grains are present, and most of them are γ grains. Repeated bending work in the state of the two-phase metal structure also makes it possible to further refine the α grains. preferable.

In the hot rolling line according to the present invention, the finish rolling mill 3, the leveler 6, and the cooling equipment 4 are arranged in this order from the upstream side to the downstream side of the rolling line. In this hot rolling line, a metal strip S is rolled by a finish rolling mill 3 into a metal strip 1, and subsequently, the metal strip 1 after finish rolling is repeatedly bent by a leveler 6,
Since it is cooled after that, the metal strip 1
The bending strain applied to the metal strip product can make the crystal grains of the metal strip product finer than ever before.

In the case of a steel strip product, the bending strain applied to the metal strip 1 by the leveler further refines the γ grains (increases γ grain boundaries) and causes lattice defects such as dislocations into the γ grains. Introduced. Lattice defects such as γ grain boundaries and dislocations serve as α nucleation sites. Therefore, it is considered that the α grains can be further refined by the action of producing a large number of α grains during the γ → α transformation.

The bending strain applied by the leveler 6 will be described in detail below with reference to FIGS. 2 (a) and 2 (b). In order to make the bending strain applied by the leveler 6 much larger than that of the conventional leveler to make the crystal grains of the metal strip product finer, the center distance between the adjacent work rolls 6a shown in FIG. It is effective to reduce 2L and increase the roll pushing amount δ.

The bending strain ε applied to the surface of the metal strip by the leveler 6 per bending is approximately expressed by the equation (1).
It is known to be given in. ε = a × δ / L ² (1) where a = 2 × h, h: thickness of metal strip 1, 2
L: center distance between adjacent work rolls 6a, δ: roll pushing amount.

The roll pushing amount δ is 0 when the metal strip 1 is sandwiched between the upper and lower work rolls 6a of the leveler 6.
And the distance at which the upper and lower work rolls 6a are pushed in from that state. For example, in the case as shown in FIG. 2 (a), the roll pushing amount δ is δ> 0, while as shown in FIG. 2 (b), the gap g between the upper and lower work rolls is the metal strip after finish rolling. When the thickness h is larger than 1 (the leveler is open), the roll pressing amount δ is δ <0. R is the radius of curvature of the metal plate 1, and r is the radius of the work roll 6a.

However, if the roll pushing amount δ becomes too large, the metal strip 1 may not be able to normally pass through the leveler. Therefore, in order to prevent this, the roll pushing amount δ of the leveler 6 is limited to +30 mm. It is desirable to do. Further, from the viewpoint of refining the crystal grains of the metal strip product, it is desirable that it is +1 mm or more. In addition, when the radius r of the work roll 6a is reduced, the roll interval 2L is narrowed, and the roll pushing amount δ is maintained to increase the bending strain ε _n in the surface longitudinal direction of the metal strip 1, the work roll 6a May become thin, and it may not be possible to counter the reaction force from the metal plate 1 due to the pushing of the roll. In such a case, it is desirable that the work roll 6a be a leveler reinforced with a backup roll.

When the number of work rolls n of the leveler is increased to increase the leveler added strain in the longitudinal direction of the metal strip surface, when the number of work rolls exceeds 30, the temperature of the metal strip 1 decreases. Then, there arises a problem that the reaction force from the metal strip 1 becomes considerably large and a problem that the leveler becomes large and the line length becomes long. Alternatively, when the number of work rolls exceeds 30, the strip temperature decreases due to heat removal by work rolls during passing, and in the case of steel, the γ → α transformation proceeds and grain refinement occurs. There is a case that the improvement charge of is hardly seen.

For this reason, it is preferable that the number of work rolls in the leveler arranged in the hot rolling line of the present invention is 30 or less. Next, the moving means for making the leveler 6 arranged on the above-described metal strip hot rolling line offline and online will be described with reference to FIGS. 3A and 3B are schematic diagrams showing the configuration of an example of a means for making a leveler offline and online according to the present invention, FIG. 3A is a plan view of a rolling line, and FIG. 3B is a side view of a truck. 4 to 6 are diagrams for explaining the offline procedure of the leveler shown in FIG. 3, and FIGS. 4 (a) and 4 (b) are diagrams similar to FIG.

The leveler 6 is arranged between the finish rolling mill and the cooling equipment, but the finish rolling mill and the cooling equipment are not shown in FIGS. Reference numeral 60 in the figure is a hot run table including a large number of conveyance rollers 60a. The transport roller 60a is driven so as to transport the metal strip 1 after finish rolling. 61 and 65 are hydraulic means,
In this case, it is a hydraulic cylinder fixed to the foundation or floor. 62 and 66 are rails.

The means for moving the leveler 6 off-line and on-line includes a hydraulic cylinder 61 and a rail 62. In this case, the movement of the leveler 6 in the direction intersecting with the rolling line is, as shown in FIG. 3 (a), the direction perpendicular to the hot rolling line as seen from above the line, but of course, it is not limited to this. Not a thing. The case shown in FIG. 3A will be described below. The hydraulic cylinders 61 are rolled so that the hydraulic cylinders 61 on both sides of the rolling line face each other, and the rods of both hydraulic cylinders 61 are rolled by the leveler 6. It is installed so that it can be connected to both sides of the line. The side surface of the leveler 6 and the rod of the hydraulic cylinder 61 can be connected / disconnected by, for example, an opening / closing latch 61a as connecting means. The rail 62 extends from the lower portion of the leveler 6 to the trolley 64 in a direction intersecting with the rolling line, but is cut in the state of having a contact or a minute gap at 62a on the way.

The above-mentioned rail 62 is mounted on the carriage 64, and a fill-in table 63 is placed on the rail so as to be movable in a direction intersecting the rolling line. The fill-in table 63 has a plurality of transport rollers capable of transporting the metal strip 1, and can be mounted in an empty space of the hot run table 60 where the leveler can be taken offline. The role of the fill-in table 63 having this conveyance roller is that when the leveler is taken offline and then continuously rolled, by mounting it in the empty space of the hot run table 60, the tip of the metal strip sticks into the empty space and the conveyance cannot be continued. It is to prevent becoming.

Further, the carriage 64 can be moved by a distance x by operating a hydraulic cylinder 65 on a rail 66 installed along the rolling line. Reference numeral Y in the drawing denotes an offline or online movement distance of the leveler 6 in a direction intersecting with the rolling line. Next, the operation of the means for making the leveler 6 of the example shown in FIG. 3 offline and online will be described. FIG. 3 shows a state in which the leveler 6 is installed between the finishing rolling mill and the cooling equipment so that the leveler 6 can repeatedly perform bending work.

The procedure for mounting the fill-in table roller 63 in the empty space of the hot run table 60 by taking the leveler 6 offline from such a state and taking the leveler offline is as follows. First, as shown in FIG. 4, the hydraulic cylinder 61 is operated to move the leveler 6 along the rail 62 by the distance Y so that the leveler 6 is retracted to the outside of the line and placed on the carriage 63.
Next, after disconnecting the hydraulic cylinder 61 and the leveler 6,
As shown in FIG. 5, the hydraulic cylinder 65 moves the carriage 64 along the rail 66 by a distance x, and the fill-in table 63 on the carriage 63 is connected to the hydraulic cylinder 61. As shown in FIG. It is drawn into the line by the pressure cylinder 61 and installed in the empty space of the hot run table 60. In this way, the leveler 6 is retracted out of the line,
The fill-in table 63 is mounted in the empty space of the hot run table 60 which can be created by taking the leveler off-line to form a conventional hot rolling line as shown in FIG.

On the other hand, when the leveler is brought online on the contrary, it may be carried out in the reverse order of the above-mentioned series of flow. When the leveler 6 is to be replaced with a new leveler during the line operation, a new leveler may be prepared in advance instead of the fill-in table 63, and the process may be performed as described above. 3 to 6, a case of a hot rolling line in which hydraulic means is installed as a moving means for moving the leveler 6 offline and online has been described, but the hydraulic means is replaced with an electric actuator such as an electric motor. It can also be a hot rolling line.

Further, in the examples of FIGS. 3 to 6 described above, the example in which the hydraulic means is installed on both sides of the rolling line is explained, but it may be installed on only one side. The same applies to the case of an electric actuator. In the hot rolling line as described above, the leveler can be simply and quickly moved in a direction intersecting with the rolling line to be offline or online. For this reason, when manufacturing leveler-free products, the leveler is placed off-line outside the rolling line, so that when the leveler-free material passes through the leveler, it sticks to the work roll surface above the leveler as in the past. The foreign matter drops onto the surface of the metal strip and is pushed into the surface of the metal strip by a pinch roll installed downstream of the cooling equipment, causing surface defects such as indentation flaws of metal strip products that do not require high strength. Can be completely prevented.

Further, if a hot rolling line is used in which the fill-in table 63 is installed in the empty space of the hot run table 60 which can be made offline, the tip of the metal strip 1 is pushed into the empty space made by making the leveler offline and conveyed. You can continue rolling stably without worrying about being unable to continue. by the way,
In the hot rolling line described above, it is preferable that the leveler can be installed at an appropriate position in the length direction of the rolling line according to the required quality of the product. For example, when producing a metal strip such as a hot-rolled steel strip for tinplate in which it is preferable to secure a flatness of flatness rather than improving the strength of the product, or to improve the descaling property in the next step rather than the strength of the product When producing hot strips of metal strips such as some preferred stainless steel strips, placing the levelers above between the cooling equipment and the pinch rolls maximizes their effect. Will lead to

FIG. 8 shows an example hot rolling line in which the leveler can be installed at an appropriate position in the length direction of the rolling line according to the material of the product and the required quality. (A) is a schematic diagram of a suitable example hot rolling line which concerns on this invention, (b) is a partial top view of an example of the leveler moving means installed in the hot rolling line of an example. 8 (a) is different from FIG. 1 in that the leveler is located at an appropriate position in the length direction of the rolling line in addition to between the finishing stand 3c and the cooling equipment 4 in accordance with the material of the product and the required quality. It can be installed in. In this case, the fill-in table 63 is installed in the middle of the cooling equipment 4 and between the cooling equipment 4 and the pinch roll 20, and it is possible to take the fill-in table 63 offline and bring the leveler 6 online at this position. There is.

FIG. 8B is a partial plan view showing the leveler moving means installed in this hot rolling line.
In this figure, the carriage 64 is aligned with the lengthwise position of the rolling line that allows the leveler 6 installed between the final stand 3c of the finishing mill 3c and the cooling equipment 4 to be put offline or online. Here, the rail 66 is between the cooling equipment 4 and the pinch roll 20 from the position in the longitudinal direction of the rolling line where the carriage 64 is between the finishing stand 3c and the cooling equipment 4 and the leveler 6 is offline and online. The leveler 6 is installed on the floor surface or foundation along the rolling line so that the leveler 6 can be moved to the position in the length direction of the rolling line where the leveler 6 is offline or online. The length of this rail 66 is almost the same as the length of the hot run table 60, and 100 ~ 2
It is 50m. Therefore, it is not realistic to use the hydraulic cylinder 65 shown in FIG. 3A as the moving means for moving the leveler 6 mounted on the carriage 64 along the length direction of the rolling line. In this case, an electric actuator such as an electric motor (not shown) is attached, and the electric actuator is attached to the dolly 64 so that the dolly 64 can travel along the rail 66 while the leveler 6 is placed. .
That is, this hot rolling line is provided with a moving means having a rail for moving the leveler 6 along the length direction of the rolling line, and by this moving means, the leveler 6 is moved.
In addition to between the finish rolling mill and the cooling equipment, it can be moved to an appropriate position in the length direction of the rolling line according to the material of the product and the required quality. Further, a moving means for moving the leveler 6 in a direction intersecting with the rolling line to make it offline or online is installed.

The same parts as those in FIGS. 3 to 6 are designated by the same reference numerals. In the hot rolling line shown in FIG. 8, in order to install the leveler 6 at an appropriate position in the length direction of the rolling line according to the material of the product and the required quality, the finish rolling mill final stand 3c and the cooling equipment 4 are installed. Take the leveler 6 offline from the space and place it on the trolley 64, and fill in the empty space where the leveler can be taken offline.
After mounting, the electric actuator moves the leveler 6 placed on the truck 64 along the rail 66 to an appropriate position in the length direction of the rolling line, and the fill-in table 63 on the line goes off-line. The leveler 6 may be brought online after being placed on the 64. The procedure for making the leveler 6 offline and online at an appropriate position in the length direction of the rolling line may be performed as described with reference to FIGS.

For example, in the case of producing a metal strip requiring flatness of flatness, or in the case of producing a metal strip requiring good descaling property in the pickling line in the next step, a finishing rolling mill and cooling The leveler 6 installed between the equipment 4 and the equipment 4 is taken offline, then moved along the length direction of the rolling line, and installed between the cooling equipment 4 and the pinch rolls 20 to bring them online. By doing so, in a metal strip such as a low carbon steel strip for tinplate, which requires flatness of flatness rather than strength improvement of the product, the flatness defect caused by uneven cooling in the cooling equipment 4 is more effective by the leveler. The shape of the product can be made better than that in the case where the leveler 6 is straightened and is repeatedly bent by the leveler 6 installed between the finish rolling mill and the cooling equipment 4 or the like.

Similarly, a metal strip such as a stainless steel strip of some kind, which requires good descaling property in the next step rather than strength improvement of the product, is also cooled by the cooling equipment 4 and then the surface of the metal strip is leveled by the leveler. Since fine cracks are formed in the scale, it is possible to steadily prevent the scale residue from occurring in the pickling line in the next step, as compared with the case where the leveler 6 installed at an improper position is repeatedly bent. The washing speed can be increased.

Alternatively, by installing a leveler in the middle of the cooling equipment 4 and making it online, for example, in the cooling equipment 7 installed downstream of the finish rolling mill, for example, Ar ₃ point temperature −50 ° C. to Ar ₃
Before adjusting the temperature of the metal strip 1 on the outlet side of the leveler, and then repeatedly bending with the leveler, when the cooling by the cooling facility 7 is insufficient, before repeatedly bending with the leveler It becomes possible to cool the metal strip of (1) to an appropriate temperature, and it is possible to more surely increase the strength of the product.

The same effects as those of the preferred hot rolling line described above can be obtained by using the hot rolling line as shown in FIGS. 9 (a) and 9 (b). Figure 9
In (a), 6b is an upper leveler and 6c is a lower leveler, and the leveler 6 is detachably connected to the upper leveler 6b and the lower leveler 6c by an appropriate detachable connecting means, for example, a fastening bolt. In the figure, 2 in the middle of the cooling equipment 4
A chain double-dashed line and a chain double-dashed line between the cooling equipment 4 and the pinch roll 20 indicate the leveler upper portion 6b to be installed at that position, and the leveler lower portion 6c installed at the same position is the leveler upper portion 6b. If there is not, the hot run table 60 constitutes a part of the line and the metal strip 1 can be conveyed.

The leveler upper part 6b has an upper work roll 6a, the leveler lower part 6c has a lower work roll 6a, and this lower work roll 6a also serves as a conveying roller 60a.
Reference numeral 61a in FIG. 9 (b) is an open / close type latch that connects the rod tip of the hydraulic cylinder 61 and the leveler upper portion 6b. In this hot rolling line, only the upper part 6b of the leveler separated from the lower part is moved in a direction intersecting with the rolling line to be offline or online, as a moving means, a hydraulic cylinder 61 as a hydraulic means, a rail 62, and finish rolling. A trolley is installed at a position in the length direction of the rolling line that allows the leveler 6 installed between the final stand 3C of the machine and the cooling equipment 4 to be brought offline and online. For this reason,
When manufacturing leveler-free products, the leveler upper part 6b can be simply and quickly taken offline to evacuate outside the line, preventing surface defects caused by tipping of leveler-free products and foreign substances adhering to the leveler. can do.

Further, as shown in FIGS. 9 (a) and 9 (b),
The leveler lower part 6c is installed between the final stand 3c of the finishing rolling mill and the cooling equipment 4 in advance, and is also installed at an appropriate position in the length direction of the rolling line according to the required quality of the product, and a part of the hot run table is installed. A rail 66 is provided in the hot rolling line as a moving means configured to move only the leveler upper part 6b along the length direction of the rolling line. Rail 66
Is a liner 6 offline between the cooling equipment 4 and the pinch rolls 20 from the position in the longitudinal direction of the rolling line where the trolley (not shown) makes the leveler 6 offline between the finishing rolling stand 3C and the cooling equipment 4. , To be able to move up to the longitudinal position of the rolling line,
It is installed on the floor or foundation along the rolling line.
In addition, with the dolly further mounting the leveler 6, the rail
A hot rolling line provided with a moving means such as an electric actuator so as to be capable of self-propelling along 66 is suitable because the following can be performed. Incidentally, FIG.
In the example of (b), only one position between the cooling equipments 4 and 7 can be placed online or offline.
It may be any one of the 6C-corresponding locations in (a), or a plurality or all locations.

For example, when manufacturing a product that requires flatness of flatness, good descaling property, etc., after removing the fastening bolts that integrate the leveler, from between the finish rolling mill and the cooling equipment. Only the upper part 6b of the leveler is hydraulic means 61, a rail 62,
66, using a trolley, move to an appropriate position in the length direction of the rolling line, and the lower part of the leveler 6c that is pre-mounted at that position
And, you can fasten it with the fastening bolt and put it online. Therefore, depending on the material and required quality of the product, it is possible to repeatedly bend the metal strip with a leveler at an appropriate position in the length direction of the rolling line. It is possible to obtain effects such as improvement in descaling property.

In the above hot rolling line, a cooling facility 7 is provided between the finish rolling mill final rolling stand 3c and the leveler 6.
It is preferable that the metal strips 1 be installed before the metal strip 1 is cooled before being repeatedly bent by the leveler, and the crystal grains of the product structure can be made finer. Furthermore, in the hot rolling line of the present invention, as shown in FIG. 10, a known joining facility 10 is arranged upstream of the finish rolling mill, and a cooling facility 4 arranged downstream of the leveler 6 is provided. It is even more preferable that the cutting equipment 16 is arranged between the coiler 5a and the coiler 5a. The joining equipment 10 in FIG. 10 is equipment for joining the tail end of the preceding metal piece and the tip of the trailing metal piece, and mainly from the coil box 11, the cropper 9a, and a group of devices of the joining device 12. Although it is configured, a deburring device 13, a joint cooling device 14, a sheet bar heating device 15 and the like shown by a dotted line may be added thereto. Also,
It is also preferable to install the cooling equipment 7.

If such a hot rolling line is used, the metal strip after finish rolling is repeatedly bent,
Upon cooling thereafter, an appropriate number of metal pieces S are joined by a joining facility, finish rolling (also called endless finish rolling), and a continuous metal strip is passed through the leveler, so that the leveler can be pushed. No tip occurs in the bonded metal strip 1 in only one place. On the other hand, in a hot rolling line in which the metal pieces are not joined before the finish rolling and the finish rolling is performed one by one, the number of tip portions at which the leveler cannot be pushed occurs.

Therefore, the hot rolling line capable of endless finish rolling has a higher yield of high-strength metal strip than the conventional hot rolling line capable of endless finish rolling and only intermittent batch rolling. It is more preferable because it can be improved.

[0044]

Example (Example 1) Using the hot rolling line shown in FIG. 1, a leveler-use product that requires high strength of the product and a leveler-free product that does not require high strength of the product were manufactured. . Products using levelers The products using levelers were obtained by hot rolling the steel slabs shown in Table 1 to a thickness of 4 mm, repeatedly bending them with a leveler, then cooling and winding with a coiler. The average grain size of the ferrite grains and the tensile strength of the steel strip products of the above were investigated. In the hot rolling,
The temperature on the exit side of the finish rolling mill is set to 900 ° C, the finish rolling is performed at the steel plate speed of 720 m / min on the exit side of the finishing rolling mill, and it is wound at 600 ° C.

In Invention Examples 1 and 3, immediately after the finish rolling, the number of work roll stages was 23, the work roll diameter was 190 mm, the roll center axis spacing (the spacing between the upper and lower sides) was 200 mm, and the roll pushing amount was 20 mm. Repeatedly bending was added at. The longitudinal surface strain ε _n given to the hot-rolled steel sheet by this leveler is calculated by (n-2) × ε (n: number of work roll steps, ε: surface strain per one time), and is approximately 0.34. ing. The leveler installed its uppermost work roll center at a position 30 m downstream from the center of the final stand of the finishing mill.

In Invention Examples 2 and 4, cooling was performed by the cooling equipment further arranged between the exit side of the finish rolling mill and the entrance side of the leveler, and the steel plate temperature on the exit side of the leveler was Ar ₃ to Ar _3. Except that the temperature was controlled so that the temperature was −50 ° C., the same procedure was performed as in Inventive Examples 1 and 3. Regarding the steel plate temperature on the exit side of the leveler, multiple cooling banks were installed within the range of 30 m between the final stand of the finishing rolling mill and the leveler, and the cooling water flow rate was up and down at maximum per unit surface area of the steel plate (corresponding to the front and back of the steel plate). ) 3200 l / m ² per minute
With the design, the number of banks that spray cooling water on the steel sheet after finish rolling is adjusted to eliminate local temperature unevenness in the longitudinal direction by following the running of the steel sheet on both the upper and lower sides. Controlled.

On the other hand, in Conventional Examples 1 and 2, cooling was performed after finish rolling in the same manner as in Inventive Example 1 except that the conventional hot rolling line shown in FIG. 12 was not repeatedly bent by a leveler. It was rolled up into a product. Table 2
The results of measurement of average crystal grain size and tensile strength of the leveler-used products of Conventional Examples 1 and 2 and Invention Examples 1, 2, 3, and 4 are shown in FIG.

[0048]

[Table 1]

[0049]

[Table 2]

In each of the steel types A and B, the invention examples 1 and 3 (No. 2 and No. 5) using the leveler were compared with the conventional examples (No. 1 and No. 4) not using the leveler. Invention Examples 2 and 4 (No.
No. 3, No. 6) has achieved higher strength. Further, in comparison with Invention Examples 1 and 3 (No. 2 and No. 5) that do not use a cooling device, Invention Examples 2 and 4 (No. 3, No. 5) to which a cooling device is applied.
It can be seen that 6) has higher strength. For leveler-free products, the leveler installed in the hot rolling line shown in Fig. 1 is evacuated to the outside of the line, and the leveler is taken offline to install a fill-in table roller in the empty space of the hot run table and finish rolling. Thereafter, the product was cooled and wound to obtain a product of Inventive Example 5. With respect to the leveler-free product of Inventive Example 5, the presence or absence of indentation defects caused by foreign matter adhering to the leveler was examined for each coil.

Table 3 shows the occurrence rate of indentation defects due to foreign matter attached to the leveler in the product not using leveler of Inventive Example 5. The rate of indentation flaws was inspected over the entire length of the upper surface for all coils of manufactured leveler-free products,
When there was an indentation flaw due to a foreign substance adhering to the leveler even at one place, the coil was used as an indentation flaw generation coil and calculated as shown in the lower column of the table.

On the other hand, as the leveler-free product of Comparative Example 1, in a hot rolling line in which the leveler is installed between the finishing rolling mill and the cooling device, the leveler is released while the leveler is installed at that position. As a leveler-free material, the other conditions were manufactured in the same manner as in Inventive Example 3, and the occurrence rate of indentation defects caused by the foreign matter adhering to the leveler was examined.
It is also shown in Table 3.

[0053]

[Table 3]

The leveler-free product of Inventive Example 5 in which the leveler installed in the hot rolling line is retracted outside the line is
It can be seen that it is possible to prevent surface defects caused by foreign matter attached to the leveler. On the other hand, in Comparative Example 1 in which the leveler was left open and the leveler was passed through the leveler, indentation defects due to foreign matter attached to the leveler occurred in some coils. (Example 2) In the hot rolling line shown in FIG.
Finished and rolled to a thickness of 1.2 mm and a width of 1600 mm
Low carbon steel hot rolled strip (Fe-0.06C-0.0
1Si-0.1Mn), the low carbon steel hot-rolled strip was cooled, then repeatedly bent by a leveler, and the product obtained by winding was taken as Invention Example 6 and the flatness of the product was examined. The flatness of the low carbon steel hot-rolled strip of Inventive Example 6 was measured by measuring the wave height h and the wavelength L, and the steepness λ = h /
It was evaluated by L × 100 (%).

Further, in the same hot rolling line, finish rolling is applied to the SUS having a thickness of 4 mm and a width of 1200 mm.
430 hot-rolled strip, the SUS430 hot-rolled strip was cooled, and then repeatedly bent by a leveler, and the product obtained by winding was taken as Invention Example 7. Descaling property in the pickling line in the next step of the product I checked. The descaling property of the SUS430 hot rolled strip of Inventive Example 7 was 8 vol% after shot blasting (10 MPa).
The evaluation was performed by the maximum value of the plate passing speed in the pickling tank which can be descaled under the condition of mixed acid (mixed acid of nitric acid and hydrofluoric acid).

The leveler has the same specifications as the leveler used in Example 1, and is installed between the finishing rolling mill and the cooling equipment 4 to be placed online so that the invention examples 1, 3 can be obtained.
After manufacturing the leveler products of (No.2, 5), the leveler 6 installed in the line was taken offline, and then moved along the length direction of the rolling line to cool the cooling equipment 4 and the pinch roll 20. I got online in the meantime. At that time, a fill-in table was installed in an empty space between the finish rolling mill and the cooling equipment 4 where the leveler 6 was made offline. In addition,
Repeated bending with the leveler 6 reduces the roll pushing amount.
It went as 10 mm.

As Comparative Examples 2 and 3, cooling equipment 4 was used.
And leveler 6 installed in the line between the pinch roll 20
Was taken off-line, then moved along the length direction of the rolling line, brought online between the finish rolling mill and the cooling equipment 4, and the others were the same as in Invention Examples 6 and 7, respectively. A fill-in table was installed in the empty space between the cooling equipment 4 and the pinch roll 20 where the leveler could be taken offline. The conditions for repeated bending with a leveler were the same as in Invention Examples 6 and 7, respectively.

The low carbon steel hot-rolled strip product of Comparative Example 2 thus obtained was examined for flatness in the same manner as in Inventive Example 6.
Regarding the SUS 430 hot rolled strip product of Comparative Example 3, the stripping speed at which descaling in the pickling line in the next step was possible was examined in the same manner as in Inventive Example 7. On the other hand, as Conventional Examples 3 and 4, the same as in Inventive Examples 6 and 7 except that the conventional hot rolling line shown in FIG. A rolled strip product was obtained. Regarding the obtained low carbon steel hot-rolled strip product of Conventional Example 3, Invention Example 6 was used.
The flatness was examined in the same manner as in Example 4, and for the SUS 430 hot rolled strip product of Conventional Example 4, the maximum striping speed at which descaling was possible in the next step pickling line was conducted in the same manner as in Inventive Example 7.

FIG. 11 shows the evaluation results of the flatness of the invention example, the comparative example and the conventional example, and the ratio of the striping speed at which descaling of the invention example and the comparative example is possible to the striping speed of the conventional example. Four
Shown in.

[0060]

[Table 4]

From the flatness measurement result shown in FIG. 11 and the descaling-passing speed ratio result shown in Table 4, an appropriate position in the length direction of the rolling line was determined according to the required quality of the product. Inventive Examples 6 and 7 in which repeated bending is performed by the leveler in Conventional Examples 3 and 4 in which the repeated bending is not performed by the leveler and repeated bending by the leveler at an inappropriate position in the length direction of the rolling line, respectively. It can be seen that the quality is improved as compared with Comparative Examples 2 and 3 in which

[0062]

EFFECTS OF THE INVENTION According to the present invention, even if the total reduction ratio in finish rolling is the same, bending strain can be applied to the metal strip in the longitudinal direction by the leveler, and the crystal grain of the metal strip product is higher than before. And the leveler can be easily and quickly moved to the offline position. As a result, a high-strength metal strip product can be obtained, and at the same time, it is possible to prevent the continuation of conveyance due to the leveler-unused material being caught and the surface defect due to the foreign matter adhering to the leveler. In addition, it is possible to perform repeated bending with a leveler at an appropriate position in the length direction of the rolling line according to the product material and required quality, so that the descalability in the next process of the product, the flatness of the product, etc. Regarding the quality items of high importance required for each product,
The improvement can be aimed at.

[Brief description of drawings]

FIG. 1 is a schematic view of an example hot rolling line according to the present invention.

FIG. 2 is an explanatory view for explaining the action of the leveler used in the present invention, in which (a) is a case where the roll pushing amount is positive,
(B) is a case where the roll pushing amount is negative.

3A and 3B are diagrams showing a configuration of an example of a leveler moving unit used in the present invention, in which FIG. 3A is a plan view and FIG. 3B is a side view.

FIG. 4 is a view for explaining the action of the moving means of the leveler shown in FIG.

FIG. 5 is a diagram explaining the operation of the leveler moving means shown in FIG. 3;

FIG. 6 is a diagram explaining the operation of the leveler moving means shown in FIG. 3;

FIG. 7 is a schematic view of a preferable hot rolling line when the leveler is not used.

FIG. 8A is a schematic view of a preferable hot rolling line according to the present invention, and FIG. 8B is a plan view of an example of a leveler moving means suitable for use therein.

9 (a) is a schematic view of another preferable hot rolling line according to the present invention, and FIG. 9 (b) is a plan view of an example of a leveler moving means suitable for use therein.

FIG. 10 is a schematic view of a suitable hot rolling line according to the present invention.

FIG. 11 is a graph showing the effect of a suitable hot rolling line according to the present invention.

FIG. 12 is a schematic view of a conventional hot rolling line.

[Explanation of symbols]

1 Metal strip (steel strip) S metal piece (slab or sheet bar) 2 rough rolling mill 3 finish rolling mill 3a work roll 3b backup roll 3c final rolling stand 4, 7 Cooling equipment 5a, 5b coiler 6 Levelers 6a Leveler work roll 6b Leveler top 6c lower leveler 9a, 9b, crop shear 20 pinch rolls 60 hot run table 60a Transport roller 61, 65 hydraulic cylinder (hydraulic means) 61a Open / close type latch (connection means) 62, 66 rails 62a rail break 63 Fill-in table 64 dolly 10 Joining equipment 11 coil box 12 splicing equipment 13 Deburring device 14 Junction cooling device 15 Seat bar heating device 16 cutting equipment Interval between upper and lower rolls h Metal strip thickness δ Roll pushing amount

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahisa Kitahama             1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Made in Kawasaki             Technical Research Institute of Iron Co., Ltd. (72) Inventor Futa Goto             1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Made in Kawasaki             Chiba Steel Works, Ltd. (72) Inventor Kazuya Miyakawa             1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Made in Kawasaki             Chiba Steel Works, Ltd. F-term (reference) 4E002 AD04 BD07 BD20

Claims (9)

[Claims] 1. A hot-rolling line for metal strips, wherein a finishing rolling mill, a leveler, and a cooling facility are installed in this order from upstream to downstream, and the leveler intersects with the hot-rolling line. The hot rolling line is equipped with a means for making it online and offline. 2. A hot strip rolling line for metal strips, wherein a leveler is arranged downstream of the finishing rolling mill, and means for moving the leveler along the length direction of the hot rolling line is provided. A hot rolling line characterized by 3. A hot strip rolling line for metal strips, wherein a leveler is arranged downstream of the finishing rolling mill, and a means for putting the leveler online and offline so as to intersect the hot rolling line is provided. A hot rolling line comprising means for moving the leveler along the length direction of the hot rolling line. 4. The hot rolling line according to claim 1, wherein a fill-in table roller is installed in an empty space of the hot run table which is vacant by taking the leveler off-line. 5. In a hot strip rolling line for metal strips, a finish rolling mill, a leveler, and a cooling facility are arranged in this order from upstream to downstream, and the leveler is configured such that an upper portion and a lower portion thereof are detachable from each other. And, the lower part of the leveler is configured as a part of a fixed hot run table, and means for making the upper part of the leveler online and offline so as to intersect with the hot rolling line is installed. . 6. A hot strip rolling line for metal strips, wherein a leveler is provided on the downstream side of the finishing mill so that the upper part and the lower part can be detached from each other, and the lower part of the leveler is formed as a part of a fixed hot run table. A hot rolling line, wherein means for moving the upper part of the leveler along the length direction of the hot rolling line is installed. 7. A hot strip rolling line for metal strips, wherein a leveler having an upper part and a lower part which can be attached to and detached from each other is arranged on the downstream side of the finishing rolling mill, and the lower part of the leveler is formed as a part of a fixed hot run table. Means for making the leveler upper part online and offline so as to intersect the hot rolling line are installed, and means for moving the leveler upper part along the length direction of the hot rolling line are installed. A hot rolling line characterized by. 8. The hot rolling line according to claim 1, wherein cooling equipment is installed between the finish rolling mill and the leveler. 9. The joining equipment is arranged upstream of the finish rolling mill, and the cutting equipment is provided between the cooling equipment and the coiler installed downstream of the leveler. The hot rolling line according to claim 1.