JP4238198B2 - Skin pass rolling machine and rolling method thereof - Google Patents

Description

  The present invention provides a skin pass rolling process that can produce a product that does not generate camber even if a metal strip having an edge drop is crushed after supplying a lubricating oil on the entry side of the skin pass rolling mill or after light rolling without lubrication. The present invention relates to a machine and a rolling method thereof.

  In general, metal strips (hereinafter also referred to as plates) used for automotive parts are cut into strips of about 100 to 300 mm after straightening a metal strip with a plate width of about 1 m and a plate thickness of about 1 to 8 mm with a leveler. After being subjected to slit processing called, a required length is cut out and secondarily formed and used. Although the curl and warpage of the metal strip wound in a coil shape are almost fully corrected by a leveler or the like, there is still room for improvement with respect to the camber after the line cutting.

FIG. 1 is a conceptual diagram showing the camber of the metal strip before and after the line cutting. The upper figure in FIG. 1 shows a metal strip S having a sheet width of about 1 m and a sheet thickness of about 1 mm to 8 mm, which has been subjected to light reduction skin pass rolling with an elongation of about 0.5% to 2.0% by a rolling mill in advance. The plate shape is straightened.
The lower diagram of FIG. 1 shows a state after the above-described metal strip S is divided into six strips as an example after leveler correction. The bending amount L in the horizontal direction of the metal strip after being cut in this way is called a camber, and as shown in the figure, the camber of the cut material at the end of the plate is large, which causes a problem. In recent years, the accuracy required for cambers by secondary manufacturers has become increasingly severe. For example, the camber is required to be 1 mm or less per 10 m length.

The cause of this camber is the residual stress distribution in the plate width direction when light-skin skin pass rolling with an elongation of about 0.5% to 2.0% is performed in advance by a rolling mill. This residual stress distribution is latent before slicing, but becomes apparent by slicing. In particular, a large camber is likely to occur when a metal strip having an edge drop is lightly rolled and a material having a large thickness and high strength is cut into a narrow width.
As a conventional technique for preventing this camber, for example, an edge portion which is an end portion in the plate width direction is not used as a product (for example, only five strips are taken from a metal strip which can be originally stripped, and both end portions are discarded or It is used for other applications that do not require much camber accuracy). Or, for the edge cut material, use a rolling mill again to lightly reduce the camber, or to cut the edge cut material with a large margin in advance, and then necessary At the same time as cutting to length, it is cut again to a predetermined plate width. By doing so, the camber problem at the edge portion can be solved, but the yield is greatly reduced and the cost is increased. As a technology that does not cause such a significant decrease in yield and cost, the residual stress distribution can be controlled in advance when performing light reduction skin pass rolling with an elongation of about 0.5% to 2.0% by a rolling mill. A method of rolling with a special rolling mill has been proposed (see, for example, Patent Document 1).
JP 05-69010 A

However, in this method, it is necessary to recreate the existing light reduction skin pass rolling mill as the above-mentioned rolling mill, which causes a new problem of increased equipment costs.
The present invention solves the above-described problems, and provides a skin-pass rolling machine for a metal strip having an edge drop that does not cause camber even if it is cut without causing a significant increase in equipment cost, and a rolling method thereof. It is an issue.

The gist of the present invention is as follows.
(1) In a skin pass rolling mill for rolling a metal strip having an edge drop, a backup roll having a flat crown or a convex crown of a parabolic pattern, and at least one end in the roll axial direction from the vicinity of the end of the metal strip A skin pass rolling mill having a work roll having a crown whose roll diameter increases toward the part and a device for applying a vertical bending force to an end of the work roll in the roll axial direction.

(2) In a skin pass rolling machine for rolling a metal strip having an edge drop, a backup roll having a flat crown or a convex crown of a parabolic pattern, and a roll end from the vicinity of the end of the metal strip on one side in the roll axis direction Work roll having a crown whose roll diameter increases toward the roll, a shift device for shifting the work roll in the roll axial direction, and a device for applying a vertical bending force to the end of the work roll in the roll axial direction And a skin pass rolling machine.

(3) In a skin pass rolling machine for rolling a metal strip having an edge drop, upper and lower backup rolls having a convex crown of a flat type or a parabolic pattern, and a roll from the vicinity of the end of the metal strip at least on one side in the roll axial direction Upper and lower work rolls having a crown whose roll diameter increases toward the end, an upper roll pair made of the upper work roll and the upper backup roll, and a lower roll pair made of the lower work roll and the lower backup roll And a device for applying a vertical bending force to the end of the work roll in the roll axis direction.

(4) In a skin pass rolling machine for rolling a metal strip having an edge drop, upper and lower backup rolls having a convex crown of a flat type or a parabolic pattern, and a roll from the vicinity of the end of the metal strip on one side in the roll axial direction Upper and lower work rolls having crowns whose roll diameter increases toward the end in the axial direction, an upper roll pair comprising the upper work roll and the upper backup roll, and a lower work roll comprising the lower work roll and the lower backup roll A skin pass rolling mill comprising: a device that crosses a roll pair; a shift device that shifts the work roll in the roll axis direction; and a device that applies a bending force in the vertical direction to an end portion of the work roll in the roll axis direction.

(5) In the method of rolling a metal strip using the skin pass rolling mill according to (1), when rolling a metal strip having an edge drop, the plate width and edge drop amount of the metal strip expected in advance are set as desired. The crown of the backup roll and the work roll is determined on the basis of the rolling load at a light reduction rate, and the bending force is set so that the exit side plate shape of the rolling mill of the metal strip being rolled becomes a desired plate shape. A rolling method characterized by controlling.

(6) In the method of rolling a metal strip using the skin pass rolling mill according to (2), when rolling a metal strip having an edge drop, a desired plate width and edge drop amount of the metal strip that are expected in advance are set as desired. The amount of crown of the backup roll and the work roll is determined based on the rolling load at a light reduction rate, and the bending force is adjusted so that the exit side plate shape of the rolling mill of the metal strip during rolling becomes a desired plate shape. And the rolling method characterized by controlling the shift amount of the said work roll.

(7) In the metal strip rolling method using the skin pass rolling mill according to (3), when rolling a metal strip having an edge drop, the plate width and edge drop amount of the metal strip that are expected in advance are set as desired. The crown of the work roll is determined based on the rolling load at a light reduction rate, and the crossing angle of the upper and lower roll pairs so that the plate shape of the metal strip being rolled becomes the desired plate shape. And a rolling method, wherein the bending force is controlled.

(8) In the method of rolling a metal strip using the skin pass rolling machine according to (4), when rolling a metal strip having an edge drop, a desired plate width and edge drop amount of the metal strip that are expected in advance are set as desired. The amount of crown of the work roll is determined based on the rolling load at a light reduction rate, and the bending force, the bending force, and the like so that the plate shape of the metal strip being rolled becomes the desired plate shape. A rolling method characterized by controlling a crossing angle of a pair of upper and lower rolls and a shift amount of a work roll.

  In (1) of the present invention, a work roll having a crown whose roll diameter increases from the vicinity of the end of the metal strip plate toward the roll end at least on one side in the roll axis direction, and the roll axis end of the work roll Since an apparatus that applies a bending force in the vertical direction is used, there is an advantage that it is only necessary to grind the work roll of an existing rolling mill. That is, it is only necessary to grind the part of the work roll that hits the edge of the plate. For example, when the present invention is carried out with one work roll, both end parts of the work roll are ground and the work roll is raised. Or you can incorporate it below. On the other hand, when the present invention is implemented with two work rolls, one end of each work roll may be ground and the work rolls may be incorporated symmetrically with each other. However, since it is necessary to prepare work rolls for each sheet width, the number of work rolls held increases. Therefore, a rolling mill that rolls a large amount of metal strips having the same width has a great effect. Further, depending on the steel type, the shape control ability may be insufficient even if a work roll bender is used, so it is necessary to attach a convex crown to the backup roll. When a convex crown is attached to the backup roll, the bender force (bending force) by the work roll bender works effectively, but the number of backup rolls held increases, which may increase the cost.

  In (2) of the present invention, in addition to (1) of the present invention, since there is a shift device that shifts the work roll in the roll axis direction, the plate width restriction described above is eliminated and the number of work rolls held is reduced. be able to. However, even if a work roll bender is used depending on the steel type, the shape control ability may be insufficient, so it is necessary to attach a convex crown to the backup roll. If a convex crown is attached to the backup roll, the vendor force works effectively, but the number of backup rolls held increases, which may increase the cost. Therefore, a rolling mill that rolls a large amount of metal strips of the same steel type (no restrictions on the sheet width) has a great effect.

  In (3) of the present invention, in addition to (1) of the present invention, an upper roll pair composed of an upper work roll and an upper backup roll intersects with a lower roll pair composed of a lower work roll and a lower backup roll. Since it has an apparatus, the same effect as the effect of attaching a convex crown to the backup roll can be obtained by controlling the crossing angle. Accordingly, the number of backup rolls in question in (1) is reduced. Can be reduced. However, since it is necessary to prepare work rolls for each sheet width, the number of work rolls held increases. Therefore, a rolling mill that rolls a large amount of metal strips having the same width (no restrictions on the steel type) has a great effect.

In (4) of the present invention, in addition to (3) of the present invention, a shift device that shifts the work roll in the roll axis direction is provided, so that the above-described plate width restriction is eliminated and (1) and (3) It is possible to reduce the number of work rolls in question and the number of backup rolls in question in (1) and (2). Therefore, a rolling mill that rolls a wide variety of metal strips (without restrictions on sheet width and steel type) has a great effect.
Here, when the crossing angle is controlled in (3) and (4) of the present invention, if the backup roll has a convex crown, the crossing angle can be reduced. Therefore, the backup roll is not limited to flat in (3) and (4) of the present invention.

(5) to (8) of the present invention represent a method for determining the convex crown of the backup roll and the crown of the work roll and the shape control method in the rolling mills of (1) to (4) described above. The method enables preferable shape control of each rolling mill.
Therefore, the present invention can provide a skin strip rolling machine for metal strip having an edge drop that does not cause camber even if it is cut without significantly increasing the equipment cost, and a rolling method thereof.

FIG. 2 is a block diagram showing a normal metal strip skin pass rolling mill. Usually, a metal strip hot rolled by a steel manufacturer is in a state called black skin with the oxide scale attached to the surface, a state called white skin with the oxide scale removed by pickling, or the state of the white skin Then, it is cold-rolled in a cold tandem rolling mill and skin-pass-rolled in a state after heat treatment in a continuous annealing furnace.
In any skin pass rolling, the metal strip before skin pass rolling is usually not trimmed, and therefore, the metal strip before skin pass rolling has edge drops formed by hot rolling or cold rolling. Exists.

Edge drop refers to the rapid decrease behavior of the plate thickness at the end of the plate due to the flatness of the work roll when rolling a metal strip with a rolling mill. Roll diameter, roll Young's modulus, rolling load It usually occurs in the range from the end of the plate to the inside of about 30-50 mm.
The problem when the metal strip having such edge drop is subjected to skin pass rolling with the ordinary rolling mill shown in FIG. 2 is specifically shown, and the contents of the present invention are described below.

  In FIG. 2, a four-high rolling mill is shown in this example. In FIG. 2, the work roll of the rolling mill is composed of an upper work roll 1 and a lower work roll 1 ', and each work roll 1, 1' is supported by an upper work roll chock 7 and a lower work roll chock 7 ', respectively. Yes. These work rolls 1, 1 'have a flat roll profile. In addition, when it is desired to extend the roll life of the work rolls 1 and 1 '(when it is desired to reduce the number of replacement of the work rolls 1 and 1'), the surface of these work rolls 1 and 1 'is subjected to chrome plating. There is also a case. Further, the surface of these work rolls 1 and 1 'has a surface roughness determined according to the needs of the customer. For example, a material called smooth bright, slightly rough scratch or rough dull is used.

  As the shape control means of the metal strip S, it is possible to apply an increase and a decrease bender force for controlling the vertical deflection of the upper and lower work rolls 1 and 1 ′ using the upper and lower work roll chocks 7 and 7 ′ as fulcrums. A vendor apparatus 12 is arranged. The backup roll is composed of an upper backup roll 2 and a lower backup roll 2 ', and each backup roll 2, 2' is supported by an upper backup roll chock 8 and a lower backup roll 8 ', respectively. The roll profile of the backup rolls 2 and 2 ′ is basically flat, but a convex crown may be imparted to the backup rolls 2 and 2 ′ with respect to the steel type when the shape control ability by the bender is insufficient. In some cases, the backup rolls 2 and 2 'that can control the roll profile of the backup rolls 2 and 2' by hydraulic pressure or the like may be used. In this way, a desired shape having no intermediate elongation or end elongation is obtained.

  A load detection device 10 is disposed on the upper backup roll chock 8 to detect loads on the work side that is one end in the roll axis direction and the drive side that is the other end. In addition, an electric reduction device 11 is disposed above the load detection device 10, and a pass line adjustment when the metal strip S is rolled is performed. Here, the metal strip S is an untrimmed hot rolled material or cold rolled annealed material, and has an edge drop.

Further, a hydraulic reduction device 9 for applying a rolling force is disposed below the lower backup roll chock 8 ′. These devices 9, 10, 11, chock 8, 8 ′, etc. are housed in the housing 13 of the rolling mill.
A reel 3 for supplying a coiled metal strip S is disposed on the entry side of the rolling mill, and a reel 4 for winding the rolled metal strip S in a coil shape is disposed on the exit side. Inlet and outlet deflector rolls 5 and 6 are arranged between 4 and the rolling mill.
Although not shown in the figure, pulse generators are installed on the entrance side and exit side deflector rolls 5 and 6, and the plate speeds of the entrance and exit side metal strips S are detected. Elongation is detected.

An experiment was conducted using the rolling mill under the conditions of the prior art. Table 1 shows the basic rolling conditions.

  First, in order to confirm the problems of the prior art, light rolling was performed under the rolling conditions shown in Table 1. In that case, the vendor is controlled to have a flat shape, but it has a high level of increased vendor power (potential medium growth), a medium level of increase vendor power (flat), and a low level of increase vendor power (latent potential) Experiments were performed under three conditions (e.g.

After leveling these samples on a separate line, they were cut using a slitting machine with a plate width of 200 mm (10 mm on both sides discarded), and the amount of camber per 10 m length was measured. . In either case, the camber was ± 0.2 mm for the four central strips except for the vicinity of the plate end, but the camber was 2.0 mm to 3.5 mm for the two strips near the plate end. It was over 1mm. Although the camber was slightly smaller for the increase vendor (potential edge growth), it was impossible to keep the camber within the target value.
This is because the reduction of the edge drop portion of the metal strip of the material is insufficient compared to the central portion in the plate width direction, and residual stress is generated at the plate end portion. Therefore, although it is sufficient to control the bender force so that sufficient reduction is applied to the edge drop portion, in that case, the rolled metal strip has an end-extended shape, and the plate shape is not corrected by the subsequent leveler. Even if the camber falls within the target value, it eventually becomes waste due to poor flatness, and there is no solution.

  Therefore, after skin pass rolling and leveler correction in the same manner, a sheet width of 200 mm (110 mm on each side was discarded) was slit using a slitting machine (5 strips), and the amount of camber per 10 m length was measured. As a result, in all cases, the camber was ± 0.3 mm for all five strips. However, the yield fell significantly.

  The present invention provides a method of rolling down lightly without damaging the plate shape efficiently and at least on one side in the roll axis direction from the vicinity of the plate end to the roll end as a method of efficiently rolling down sufficient for the edge drop of the metal strip of the material. Work rolls 1 and 1 'having a crown with an increasing roll diameter are employed. Further, backup rolls having a convex crown are adopted as the backup rolls 2 and 2 'as required.

  The crowns of the work rolls 1 and 1 'described above must basically be changed for each sheet width and rolling load level. When the roll crown is attached to both ends of the work rolls 1 and 1 ′, it is not always necessary to attach the crown of the work rolls 1 and 1 ′ to the upper and lower work rolls 1 and 1 ′. Either one of 1's may be used. In this case, a slight C warpage may occur in the metal strip S after light rolling, but this is not a problem because it is sufficiently corrected by the leveler in the next step.

  Further, the above-described crown of the work rolls 1 and 1 ′ is applied only to one end, and the work rolls 1 and 1 ′ are arranged in point symmetry, and the upper and lower work rolls 1 and 1 ′ are arranged in the roll axial direction. By being configured so as to be shiftable, the above-described plate width restriction is substantially eliminated, and the number of crowned work rolls 1, 1 ′ can be significantly reduced. Further, by using a roll whose roll crown can be controlled as the backup rolls 2 and 2 ', the number of backup rolls 2 and 2' provided with a crown can be significantly reduced. Further, as described above, instead of providing a convex crown to the backup rolls 2 and 2 ', a pair of the upper work roll 1 and the upper backup roll 2 and a pair of the lower work roll 1' and the lower backup roll 2 ' Each of the pair of rolls may be a pair of cross mills that can change the cross angle between the two roll pairs, and the cross angle may be controlled.

FIG. 3 is a configuration diagram (front view) showing an embodiment of the skin pass rolling mill of the present invention. In FIG. 3, the work roll of the rolling mill is composed of an upper work roll 1 and a lower work roll 1 ′, and each work roll 1, 1 ′ has an upper work roll chock 7 and a lower work roll chock (not shown in FIG. 3). 7 'is supported by each. The roll profiles of these work rolls 1 and 1 'have a crown whose roll diameter increases from the vicinity of the plate end toward the roll end on one side in the roll axial direction. Specifically, in the work rolls 1 and 1 ′ having a drum length (length in the roll axis direction) of 2000 mm, a position 400 mm inward from the end of one of the rolls is set as a taper start point P, and the roll end from there. A crown is provided so that the roll diameter gradually increases in a taper shape from 0 to 50 microns / radius. In addition, the crown is not given to other parts, but it is flat.
And these work rolls 1 and 1 'are arrange | positioned point-symmetrically with respect to the centerline Y of the said roll axial direction in a mill (rolling mill). Further, this rolling mill is equipped with a device capable of shifting these work rolls 1 and 1 ′ in the roll axis direction, and the side to which the crown is applied is shifted inward by 50 mm toward the center line Y. Has been. Although not shown in FIG. 3, as a shape control means, an increment and a decrease bender force for controlling the vertical deflection amount of the upper and lower work rolls 1 and 1 ′ with the upper and lower work roll chocks 7 and 7 ′ as fulcrums. Is provided, a force of 40 tons per chock is applied, and a flat shape is obtained as a plate shape.

The backup roll is composed of an upper backup roll 2 and a lower backup roll 2 ′, and each backup roll 2, 2 ′ is supported by an upper backup roll chock 8 and a lower backup roll chock 8 ′ not shown in FIG. ing. These backup rolls 2, 2 'are provided with a convex crown of 400 microns / radius in a parabolic pattern over the entire length of 2000 mm.
In FIG. 3, a load detection device 10 is disposed above the backup roll chock 8 (not shown), and the loads on the work side and the drive side are detected. In addition, an electric reduction device 11 (not shown in FIG. 3) is disposed above the load detection device 10, and a pass line adjustment when the metal strip S is rolled is performed.
This metal strip S is a high-tensile material with a yield strength of 600 MPa, which is an untrimmed white-skinned hot rolled material, and has a plate thickness of 1.2 mm, a plate width of 1100 mm, and an edge drop extending about 50 mm from the plate end. . The edge drop amount is the difference in plate thickness 15 mm inside from the plate center and the plate edge, and is about 40 microns.

Lubrication is non-lubricated, and rolling is performed at an elongation of about 2% and a rolling load of about 890 tons. Table 2 shows the rolling conditions in the examples of the present invention.

As an example of the prior art for comparison, the backup rolls 2 and 2 ′ are the same as those in Table 2, but the work rolls 1 and 1 ′ are flat rolls, and the shift amount is zero, and the metal strip S Was rolled. In either case, the bender force was controlled so that the plate shape was flat.
After leveling the samples on a separate line, they were cut using a slitting machine with a plate width of 200 mm (5 mm on each side was discarded), and the amount of camber per 10 m length was measured. .
As a result, in the embodiment of the present invention, for all the five strips taken, all the cambers were within the range of ± 0.2 mm, but in the case of the prior art, 2 near the plate end. For one of the strips, the camber (absolute value) was 1.5 mm to 3.0 mm, exceeding the target of 1 mm.

As is apparent from the above, the metal strip S in which no camber is generated after the slitting cannot be produced by the prior art. On the other hand, in the present invention, by adopting the work rolls 1 and 1 ′ whose work roll diameter increases toward at least one roll end, it is possible to obtain a plate end that is unlikely to be pressed down by the metal strip S having an edge drop. As a result, the metal strip S can be sufficiently reduced, and as a result, the metal strip S in which no camber is generated after the slitting can be manufactured. Further, by making the crowns of the backup rolls 2 and 2 ′ convex, the shape control by the bender device 12 can be effectively executed, and as a result, the metal strip S with good flatness can be manufactured. . Furthermore, as shown in FIG. 3, since the taper starting point P of the crown of the work rolls 1 and 1 'is set outside the metal strip S, the roll marks and the like that may be generated on the metal strip S due to the tapered crown. This makes it possible to produce a metal strip S with excellent surface properties.
In addition, as shown in FIG. 3, although the edge-drop part of the metal strip S does not hit the provision part of the taper-shaped crown in the work rolls 1 and 1 ′, it is sufficient for the edge drop part. The reason why it is possible to apply the reduction is that when the tapered crown hits the backup rolls 2 and 2 ′, the flat portion in the vicinity of the taper start point P in the work rolls 1 and 1 ′ causes the reduction. Because it bends enough to give.

It is a conceptual diagram which shows the camber of the metal strip before and behind cutting. It is a block diagram which shows the skin pass rolling mill of a normal metal strip. It is a block diagram (front view) which shows one Embodiment of the skin pass rolling mill of this invention.

Explanation of symbols

1 Upper work roll 1 'Lower work roll 2 Upper backup roll 2' Lower backup roll 3 Rewind reel 4 Take-up reel 5 Incoming deflector roll 6 Outlet deflector roll 7 Upper work roll chock 7 'Lower work roll chock 8 Upper backup roll chock 8 'Lower backup roll chock 9 Hydraulic reduction device 10 Load detection device 11 Electric reduction device 12 Bender device 13 Housing S Metal strip Y Mill centerline P Taper start point

Claims (8)

In a skin pass rolling machine for rolling a metal strip having an edge drop,
A backup roll having a convex crown of a flat type or a parabolic pattern;
A work roll having a crown whose roll diameter increases from the vicinity of the end of the metal strip toward the end of the roll on at least one side in the roll axis direction;
And a device for applying a vertical bending force to an end of the work roll in the roll axial direction. In a skin pass rolling machine for rolling a metal strip having an edge drop,
A backup roll having a convex crown of a flat type or a parabolic pattern;
A work roll having a crown whose roll diameter increases from the vicinity of the end of the metal strip toward the end of the roll on one side in the roll axis direction;
A shift device for shifting the work roll in the roll axial direction;
And a device for applying a vertical bending force to an end of the work roll in the roll axial direction. In a skin pass rolling machine for rolling a metal strip having an edge drop,
Upper and lower backup rolls having a flat or parabolic pattern convex crown;
Upper and lower work rolls having crowns whose roll diameter increases from the vicinity of the end of the metal strip toward the roll end on at least one side in the roll axis direction;
An apparatus for crossing the upper roll pair consisting of the upper work roll and the upper backup roll and the lower roll pair consisting of the lower work roll and the lower backup roll;
A skin pass rolling machine comprising a device for applying a vertical bending force to an end of the work roll in the roll axial direction. In a skin pass rolling machine for rolling a metal strip having an edge drop,
Upper and lower backup rolls having a flat or parabolic pattern convex crown;
Upper and lower work rolls having crowns whose roll diameter increases from the vicinity of the end of the metal strip toward the end in the roll axis direction on one side in the roll axis direction;
An apparatus for crossing the upper roll pair consisting of the upper work roll and the upper backup roll and the lower roll pair consisting of the lower work roll and the lower backup roll;
A shift device for shifting the work roll in the roll axis direction;
A skin pass rolling machine comprising a device for applying a vertical bending force to an end of the work roll in the roll axial direction. In the rolling method of the metal strip using the skin pass rolling mill according to claim 1,
When rolling a metal strip having an edge drop, the crown of the backup roll and the work roll is determined based on the expected width of the metal strip, the amount of edge drop, and the rolling load at a desired light reduction rate. And
A rolling method, wherein the bending force is controlled such that a shape of a delivery plate of the rolling mill of the metal strip being rolled becomes a desired plate shape. In the rolling method of the metal strip using the skin pass rolling mill according to claim 2,
When rolling a metal strip having an edge drop, the crown amount of the backup roll and the work roll is determined based on the metal strip width, edge drop amount, and rolling load at a desired light reduction rate. Decide
A rolling method, wherein the bending force and the shift amount of the work roll are controlled such that a shape of an exit side plate of the rolling mill of the metal strip being rolled becomes a desired plate shape. In the rolling method of the metal strip using the skin pass rolling mill according to claim 3,
When rolling a metal strip having an edge drop, the crown of the work roll is determined based on a plate width and an edge drop amount that are expected in advance and a rolling load at a desired light reduction rate,
A rolling method, wherein the crossing angle and the bending force of the pair of upper and lower rolls are controlled so that a plate shape of the metal strip being rolled becomes a desired plate shape. In the rolling method of the metal strip using the skin pass rolling mill according to claim 4,
When rolling a metal strip having an edge drop, the crown amount of the work roll is determined on the basis of a rolling load at a desired light reduction rate and a plate width and an edge drop amount of the metal strip that are predicted in advance.
The bending force, the crossing angle between the upper and lower roll pairs, and the shift amount of the work roll are controlled so that the plate shape on the delivery side of the rolling mill of the metal strip being rolled becomes a desired plate shape. Rolling method to do.